06 April 2023

–Narmada Khare

Just like humans, animals move about to find food, shelter, and mates. Movement in the wild, however, comes with increased risk, as it can be tracked by predators.

To understand how katydids (bushcrickets) are hunted by their predator – the lesser false vampire bat – a group of researchers led by Rohini Balakrishnan, Professor at the Centre for Ecological Sciences (CES), Indian Institute of Science (IISc), fitted tiny radio tags onto these insects and tracked their movement in the canopy. They found that female katydids are at greater risk than males, likely because the former are frequent fliers who cover longer distances.

Published in Behavioral Ecology and Sociobiology, this is the first insect radio tracking study in India, explains Harish Prakash, postdoc at CES and an author of the paper. He says that in addition to field observation, they carried out experiments in a controlled environment to answer key research questions on predator-prey interactions.

Lesser false vampire bats – native to South and Southeast Asia – bring their prey back to their roost to eat. A large proportion of the bat diet consists of insects like katydids. In earlier studies, Balakrishnan and others found that there were a lot more remnants of female wings than males, suggesting that the bats preferred to prey on female katydids. This was unexpected, because katydid females are usually silent, unlike the males that make themselves conspicuous by calling out to attract the females. This led the researchers to ask the question: What about katydid females made them more attractive to the bats?

A whistler male with radio tag attached (Credit: Kasturi Saha)

One possibility is that bats can detect females more easily, since they are usually larger than males. Second, female katydids might be more nutritious than males and therefore preferred by bats. To test these possibilities, the researchers focused on a group of katydids called “whistlers”, in which females are almost double the size and weight of the males. They presented free-flying whistler females as well as males to bats in a large, outdoor cage. Surprisingly, the bats approached both males and females with equal frequency. In fact, in this experimental setup, females escaped capture more often than males. So, it was not the size or nutritive value of the females that increased the risk of their predation.

Then the researchers hit on a third possibility: perhaps the females were flying out more often. To test this, the team glued tiny radio transmitters onto the backs of male and female katydids and tracked them as they flew across trees. What they found was that females tend to move 1.5 times more frequently and 1.8 times farther than males. This led them to conclude that flying more frequently and traveling longer distances across trees may put females at a higher risk of being hunted by bats than males. Kasturi Saha, PhD student at CES and corresponding author on the paper, suggests a possible reason for these frequent long flights: “The females may move around in search of mates, as well as suitable egg-laying sites”.

Lesser false vampire bat (Credit: Kasturi Saha)

“In systems where males produce conspicuous acoustic signals and females move silently, it has been assumed that males rather than females perform the higher-risk behaviours,” says Balakrishnan. However, contrary to this view of risk-taking males and risk-averse females, the current study shows that female katydids might be at greater risk of predation.

There are still many unanswered questions about predator-prey interactions. For example, Saha explains that the bats seem to hunt more female katydids during non-breeding seasons. “This is another mystery we are trying to solve.”

REFERENCE:
Saha K, Prakash H, Mohapatra PP, Balakrishnan R, Is flying riskier for female katydids than for males? Behavioral Ecology and Sociobiology (2023).
https://link.springer.com/article/10.1007/s00265-023-03298-7

CONTACT:
Kasturi Saha
PhD student
Centre for Ecological Sciences (CES)
Indian Institute of Science (IISc)
Phone: 9486172985
Email: kasturisahaks@iisc.ac.in

Rohini Balakrishnan
Professor
Centre for Ecological Sciences (CES)
Indian Institute of Science (IISc)
Phone: +91-80-23602971
Email: brohini@iisc.ac.in
Website: https://sites.google.com/view/rohinibalakrishnanlab/home

NOTE TO JOURNALISTS:
a) If any of the text in this release is reproduced verbatim, please credit the IISc press release.
b) For any queries about IISc press releases, please write to news@iisc.ac.in or pro@iisc.ac.in .

17 April 2023

– Shrivallabh Deshpande

What did the Earth look like about two billion years ago, when the planet’s atmosphere was being oxygenated?

By analysing ancient dolomite (carbonate) deposits found in Vempalle, in the Cuddapah district of Andhra Pradesh, researchers at the Indian Institute of Science (IISc) and the University of Tennessee have estimated the temperature and composition of a shallow, inland sea that most likely existed back in that time, called the Palaeoproterozoic era.

Their findings provide insight into how the conditions during that time provided just the right ambience for the emergence and bloom of photosynthetic algae. It also shows how a wealth of data about our planet’s past remains hidden inside ancient rocks.

“The story of our planet is written in the different strata of rocks,” explains Prosenjit Ghosh, Professor at the Centre for Earth Science (CEaS), IISc, and corresponding author of the study published in Chemical Geology.

Outcrop of the Palaeoproterozoic section in the Cuddapah basin (Photo: Yogaraj Banerjee)

Planet Earth hasn’t always been this hospitable for life. It has been through different phases of climatic extremes, including periods when carbon dioxide levels were almost too toxic for living creatures, just like our neighbour, Venus. However, various studies of fossils from the Palaeoproterozoic era have shown that some life might have existed even under these harsh conditions.

The large amounts of CO2 in the atmosphere were absorbed by the sea and trapped as carbonates in dolomites, says Yogaraj Banerjee, a former PhD student from CEaS and one of the authors.

“[Dolomite] is a direct precipitate from seawater. It provides a signal not only of seawater chemistry but also of seawater temperature,” explains Robert Riding, Research Professor at the Department of Earth and Planetary Sciences, University of Tennessee, USA, and another author of the study.

The team of researchers collected dolomite samples from chert – hard rocks formed by the interaction of microbes with seawater – as well as deposits underneath them called dolomitic lime-mud. Having first identified the strata of rock where the dolomitic mud could be found, the researchers extracted and transported them back to the lab. Then, they used a state-of-the-art technique known as clumped isotope thermometry to analyse them. The technique allows scientists to narrow down the temperature and composition of the deposits by looking at the arrangement of the carbon and oxygen bonds.

After two years of intense analysis, the team was able to figure out from the dolomitic mud that the temperature of the seawater during its original time period was about 20°C. This is in contrast to previous studies that analysed only chert samples from around the same period, and had estimated that the temperature was higher, around 50°C. The lower temperature estimate from the current study agrees more closely with the theory that the conditions were ideal for supporting lifeforms.

During the Palaeoproterozoic era, the type of water present was earlier believed to be only heavy water, containing a specific set of isotopes or forms of hydrogen. However, in the current study, the team showed that light water – the regular form of water found even today – was also present back then.

Palaeoproterozoic (around 2 billion years-old) stromatolite fossils studied in this project (Photo: Yogaraj Banerjee)

Taken together, these insights – the lower seawater temperature and the presence of light water – strongly support the hypothesis that the conditions around two billion years ago were just right for photosynthetic algae to emerge. These algae were mainly responsible for pumping oxygen into the atmosphere, and making way for other lifeforms to evolve and populate the planet.

“It is fascinating to unravel the conditions that led to the emergence of life from a rock which was waiting to be picked up,” says Sanchita Banerjee, former PhD student at CEaS and first author of the study.

The team now plans to search for similar lime-mud deposits in other places around the world to gather additional insights about the Palaeoproterozoic era.

REFERENCE:

Banerjee S, Ghosh P, Banerjee Y, Riding R, Oxygen isotopic composition of Paleoproterozoic seawater revealed by clumped isotope analysis of dolomite, Vempalle Formation, Cuddapah, India, Chemical Geology(2023).

CONTACT:

Prosenjit Ghosh
Professor, Centre for Earth Sciences (CEaS) & Divecha Centre for Climate Change
Indian Institute of Science (IISc)
Email: pghosh@iisc.ac.in
Phone: +91-80-2293-3403
Lab website: https://www.oasislab.co.in/

Yogaraj Banerjee
Postdoctoral research fellow, National Taiwan University
Former PhD student, Centre for Earth Sciences (CEaS)
Indian Institute of Science (IISc)
Email: ybanerjee15@gmail.com

Robert Riding
Research Professor, Department of Earth and Planetary Sciences
University of Tennessee
Email: rriding@utk.edu

NOTE TO JOURNALISTS:

a) If any of the text in this release is reproduced verbatim, please credit the IISc press release.
b) For any queries about IISc press releases, please write to news@iisc.ac.in or pro@iisc.ac.in.

01 May 2023

A multi-institutional study on dengue led by researchers at the Indian Institute of Science (IISc) shows how the virus causing the disease has evolved dramatically over the last few decades in the Indian subcontinent.

Cases of dengue – a mosquito-borne viral disease – have steadily increased in the last 50 years, predominantly in the South-East Asian counties. And yet, there are no approved vaccines against dengue in India, although some vaccines have been developed in other countries.

“We were trying to understand how different the Indian variants are, and we found that they are very different from the original strains used to develop the vaccines,” says Rahul Roy, Associate Professor at the Department of Chemical Engineering (CE), IISc, and corresponding author of the study published in PLoS Pathogens. He and collaborators examined all available (408) genetic sequences of Indian dengue strains from infected patients collected between the years 1956 and 2018 by others as well as the team themselves.

Dengue virus evolution in India (Image: Suraj Jagtap)

There are four broad categories – serotypes – of the dengue virus (Dengue 1, 2, 3 and 4). Using computational analysis, the team examined how much each of these serotypes deviated from their ancestral sequence, from each other, and from other global sequences. “We found that the sequences are changing in a very complex fashion,” says Roy.

Until 2012, the dominant strains in India were Dengue 1 and 3. But in recent years, Dengue 2 has become more dominant across the country, while Dengue 4 – once considered the least infectious – is now making a niche for itself in South India, the researchers found. The team sought to investigate what factors decide which strain is the dominant one at any given time. One possible factor could be Antibody Dependent Enhancement (ADE), says Suraj Jagtap, PhD student at CE and first author of the study.

Jagtap explains that sometimes, people might be infected first with one serotype and then develop a secondary infection with a different serotype, leading to more severe symptoms. Scientists believe that if the second serotype is similar to the first, the antibodies in the host’s blood generated after the first infection bind to the new serotype and bind to immune cells called macrophages. This proximity allows the newcomer to infect macrophages, making the infection more severe. “We knew that ADE enhances severity, [but] we wanted to know if that can also change the evolution of dengue virus,” Jagtap adds.

At any given time, several strains of each serotype exist in the viral population. The antibodies generated in the human body after a primary infection provide complete protection from all serotypes for about 2-3 years. Over time, the antibody levels begin to drop, and cross-serotype protection is lost. The researchers propose that if the body is infected around this time by a similar – not identical – viral strain, then ADE kicks in, giving a huge advantage to this new strain, causing it to become the dominant strain in the population. Such an advantage lasts for a few more years, after which the antibody levels become too low to make a difference. “This is what is new about this paper,” says Roy. “Nobody has shown such interdependence between the dengue virus and the immunity of the human population before.” This is probably why the recent Dengue 4 strains, which supplanted the Dengue 1 and 3 strains, were more similar to the latter than their own ancestral Dengue 4 strains, the researchers believe.

Such insights are possible only from studying the disease in countries like India with genomic surveillance, explains Roy, because the infection rates here have been historically high, and a huge population carries antibodies from a previous infection.

REFERENCE:

Jagtap S, Pattabiraman C, Sankaradoss A, Krishna S, Roy R, Evolutionary dynamics of dengue virus in India, PLoS Pathogens (2023).
The work was supported by a philanthropic grant from Narayana Murthy, co-founder and chairman emeritus of Infosys Limited, and funding from the Wellcome Trust-DBT India Alliance.

CONTACT:

Rahul Roy
Associate Professor
Department of Chemical Engineering (CE)
Indian Institute of Science (IISc)
Email: rahulroy@iisc.ac.in
Phone: 080-2293 3115
Lab website: https://nanobiology.nanobiophotonics.org/

Suraj Jagtap
PhD student
Department of Chemical Engineering (CE)
Indian Institute of Science (IISc)
Email: jsuraj@iisc.ac.in

NOTE TO JOURNALISTS:

a) If any of the text in this release is reproduced verbatim, please credit the IISc press release.

b) For any queries about IISc press releases, please write to news@iisc.ac.in or pro@iisc.ac.in.

3 May 2023

The UK and India are set to become first movers in the transition to Net Zero transport systems, thanks to a pioneering innovation partnership, led by Energy Systems Catapult.

Innovating for Transport and Energy Systems (ITES) is a unique collaboration to develop greener, quicker and more affordable ways for people and goods to move around – in India, the UK, and beyond.

Backed by governments in both the UK and India, UK Research and Innovation (UKRI), and delivered in partnership with the Indian Institute of Science (IISc), the initiative will for the first time bring together innovators, industry heavyweights, researchers, policymakers and investors from both countries to target the transport system’s toughest decarbonisation challenges, such as developing an electric vehicle-ready infrastructure.

The initiative is one of the first to be announced following a landmark Memorandum of Understanding (MoU) signed by UK and India Science Ministers last Wednesday, 26 April, in Westminster, to boost science and innovation, and deliver economic growth across the two countries.

ITES will offer a ‘soft-landing’ for UK SMEs interested in the Indian market, and opportunities for SMEs and start-ups in India, helping innovators to safely develop, test and export solutions that help decarbonise transport, thanks to low-risk, high-impact pilots with trusted partners. The collaboration will also help SMEs tackle scalability with go-to-market support and access to potential clients, funders and investment.

Adopting a perspective across the whole transport and energy system, ITES will consider the multiple solutions needed to deliver cleaner seas, skies, roads and railways. Cutting-edge pilots and research programmes in India and the UK will test technologies and explore pathways for sustainable and clean transport – such as electric and hydrogen solutions – that are reliable, affordable and acceptable to businesses and consumers, as well as ensuring an infrastructure and energy generation system that can meet demand.

ITES aims to attract public, private and third sector partners and sponsors to ensure activities are market-led and solve practical problems, such as zero-emission fleets and last-mile delivery, and innovative charging technologies. By combining resources, the programme will make it more cost-effective for the UK and India to develop world-first pilot projects and Net Zero solutions.

Guy Newey, Chief Executive at Energy Systems Catapult, said: “Decarbonising transport is one of the greatest challenges we face. This is not a hurdle we can overcome alone. By linking innovators, researchers, and investors together in the UK and India we can unlock financial investments, accelerate the pace of decarbonisation, and flex our collective low-carbon muscle.

“The partnership underlines how innovation from SMEs will be at the heart of the Net Zero transition and affords them an opportunity to collaborate and trial their solutions in the world’s fifth biggest economy – turbocharging decarbonisation efforts and unleashing economic potential.”

The initiative will be steered by in-country partner, the Indian Institute of Science (IISc).

Prof Ashish Verma, Convenor, IISc Sustainable Transportation (IST) Lab, said, “India is currently passing through an interesting phase of economic growth and infrastructure development in many sectors including transport, which provides a great opportunity for the country to leapfrog to a sustainable and Net Zero future.

“We are committed to exploring disruptive, cutting-edge and collaborative solutions. Complementing these efforts, ITES, which is anchored within the IST lab, will harness the UK and India’s rich reputation for R&D and the strength of our business sectors to pioneer test beds that unlock better data, clearer decision-making and bolder collective action from industry and leaders in the transport and energy sector.”

ITES will form part of the new UK-India Net Zero Innovation Virtual Centre, a key coalition forged as part of the Memorandum of Understanding signed last week, to help maximise cooperation on Net Zero action.

Backed by the UK Government, the Centre will be facilitated by the UK Science and Innovation Network in India, hosting programmes such as the Hydrogen Valley and Industrial Decarbonisation Living Lab to help decarbonise manufacturing and – through the ITES initiative – transport systems.

The launch of ITES builds on the success of former initiatives to boost innovation between the UK and India, such as the Innovating for Clean Air (IfCA) programme. Led by Energy Systems Catapult, with partners including the Indian Institute of Science, the programme enabled the adoption of clean EV technologies and services by proving solutions across real-life testbeds in India.

Sarah Fallon, Regional Director (India, Middle East), Science, Innovation and Tech, British High Commission, New Delhi said: “Our ambition is that ITES will be a long-term, established base for UK-India superpower partnerships and programmes that shape the future of Net Zero transport systems, and that can be expanded to other sectors over time.

“We are confident that this initiative will help accelerate the development of innovative solutions for greener transport systems in India and overseas, and bring us closer to our shared goal of Net Zero emissions – an ambition that can only be realised with international collaboration.”

London-based business GreenEnco is among the UK innovators that has expanded its offering in India after demonstrating its EV charging station solution, and gaining support to develop a mobile app as part of the project. The company is now applying its expertise to help deliver faster electric vehicle charging solutions in India, while also supporting local industry.

GreenEnco Chief Executive Officer Dr Jyotirmoy Roy said: “Through international programmes such as IfCA, ESC and their partners have provided innovative businesses like ours with the safe springboard we need to develop overseas, opening doors in India to help us collaborate and commercialise across borders. We have now committed with our integrated green energy solution to help develop a fast EV charging infrastructure in India.

“We’re delighted that our innovative solution will not only make an environmental impact to help decarbonise the transport sector, but – with our locally-procured system components – we are also supporting the development of a sustainable socio-economical ecosystem in India.”

About Energy Systems Catapult

Energy Systems Catapult was set up to accelerate the transformation of the UK’s energy system to reach Net Zero and ensure UK businesses and consumers capture the opportunities of clean growth. The Catapult is an independent, not-for-profit centre of excellence that bridges the gap between industry, government, academia and research. We take a whole systems view of the energy sector, helping us to identify and address innovation priorities and market barriers, in order to decarbonise the energy system at the lowest cost.

About the Indian Institute of Science (IISc)

The Indian Institute of Science (IISc) was established in 1909 by a visionary partnership between the industrialist Jamsetji Nusserwanji Tata, the Mysore royal family and the Government of India. Over the last 113 years, IISc has become India’s premier institute for advanced scientific and technological research and education. Its mandate is “to provide for advanced instruction and to conduct original investigations in all branches of knowledge as are likely to promote the material and industrial welfare of India.” In 2018, IISc was selected as an Institution of Eminence (IoE) by the Government of India, and it consistently figures among the top Indian institutions in world university rankings.

CONTACT:

Stuart Brennan, Head of Communications and Marketing
Email: stuart.brennan@es.catapult.org.uk
http://es.catapult.org.uk/

IISc Office of Communications
Email: news@iisc.ac.in

16 May 2023

During 9-18 May 2023, the Telecommunication Engineering Centre (TEC), Department of Telecommunications (DoT) and the Indian Institute of Science (IISc), Bengaluru are hosting the meeting of ITU-T Study Group 9 (SG-9) on “Broadband Cable and Television/Audiovisual content transmission and integrated broadband cable networks” at the IISc campus.

This is the first physical meeting of the SG-9 after the COVID-19 pandemic. This is also the first time that the SG9 meeting is being hosted by India. The event was attended by delegates and representatives from Bangladesh, Brazil, China, Congo, Egypt, France, Gambia, Germany, India, Japan, Kenya, Korea, Myanmar, Nepal, Palestine, Sri Lanka, Syria, Switzerland, Tanzania, Thailand, Ukraine, and other countries. In addition, representatives of the International Telecommunication Union (ITU), a UN Organisation, and many other experts attended the meeting.

ITU is the oldest UN agency, founded in 1865, to facilitate international connectivity in communications networks. ITU allocates global radio spectrum and satellite orbits, develops the technical standards that ensure networks and technologies seamlessly interconnect, and strives to improve access to Information and Communications Technologies (ICTs) to underserved communities worldwide. The Study Group 9 at ITU is responsible for telecommunication systems for primary and secondary distribution of audiovisual content, including accessibility services and emerging interactive media.

The ITU SG9 meeting was held at the Department of Electrical Communication Engineering, IISc. During the inaugural session on 9 May 2023, Mr Avinash Agarwal, DDG(C&B) TEC; Dr Satoshi Miyaji, Chairman of ITU-T SG9; Prof Rajesh Sundaresan, Dean of the Division of Electrical, Electronics, and Computer Sciences at IISc; Prof Pradipta Biswas, Vice-Chair of ITU-T SG9, and the TSB team from ITU Geneva were present.

The SG9 meeting organised sessions to discuss the 11 questions assigned by the ITU Membership at the previous World Telecommunication Standardisation Assembly. The SG9 looks at different aspects of transmission, distribution, and rendering of cable and broadband TV, after considering multiple contributions submitted by ITU Members, of which a large part has come from India and Indian stakeholders, including a draft recommendation on a Common User Profile, which is a work item led by IISc. On Wednesday, 10 May 2023, a virtual meeting of IRG-AVA, an ITU group trying to improve accessibility of audio-visual media by coordinating inputs from representatives of ITU-D, ITU-R and ITU-T Sectors, was held.

The Study Group meeting also comprised the ITU Workshop on The Future of Television for South Asia, Arab and Africa Regions, which was held on 11 May 2023, covering regulatory and policy frameworks, emerging and convergent ICT infrastructures and services, as well as user interfaces and human factors. The workshop was held in hybrid mode and was attended by more than 200 participants from over 50 different countries. The speakers included eminent experts such as Premjit Lal​, Deputy Director General (International Relations), Department of Telecommunications, Ministry of Communications, India​; Prof Rajesh Sundaresan, Dr Satoshi Miyaji, and Mr Seizo Onoe​, Director, Telecommunication Standarisation Bureau, ITU. The event was accompanied by demos from various industries and research labs including C-DOT, Saankhya Labs, ITI, Qualcomm, Exalto, and Doordarshan as well as three IISc Labs – Centre for Networked Intelligence, 5G test bed, and I3D Labs.

Mr Seizo Oneo, TSB Director, speaking about the event, said, “I thank India’s Ministry of Communications and the Indian Institute of Science for their hard work in arranging the workshop, as well as your hospitality to ITU-T Study Group 9 as the hosts. At the workshop, while the future technologies of digital broadcasting were discussed, it was also highlighted that many countries are still facing challenges in transitioning from analog to digital broadcasting. I hope that the ITU workshop will serve as a platform for sharing best practices and help bridge the gap.”

RELATED LINKS:

ITU Future of TV: ITU Workshop on “The Future of Television for South Asia, Arab and Africa Regions”

ITU SG 9: ITU-T SG9: Broadband cable and TV

ITU: ITU: Committed to connecting the world

CONTACT:

Office of Communications, IISc | news@iisc.ac.in

26 May 2023

– Akash Kalita

Like thieves that constantly look for ways to evade capture, Salmonella enterica, a disease-causing bacterium, uses various tactics to escape the human body’s defence mechanisms. In a new study, researchers from the Department of Microbiology and Cell Biology (MCB), IISc, highlight two such strategies that the bacterium uses to protect itself, both driven by the same protein.

When Salmonella enters the human body, each bacterial cell resides within a bubble-like structure known as Salmonella-containing vacuole (SCV). In response to the bacterial infection, the immune cells in our body produce reactive oxygen species (ROS) and reactive nitrogen species (RNS), along with pathways triggered to break down these SCVs and fuse them with cellular bodies called lysosomes or autophagosomes, which destroy the bacteria. However, these bacteria have developed robust mechanisms to maintain vacuolar integrity, which is crucial for their survival. For example, when a bacterial cell divides, the vacuole surrounding it also divides, enabling every new bacterial cell to be ensconced in a vacuole. This also ensures that more vacuoles are present than the number of lysosomes which can digest them.

In the study published in Microbes and Infection, the IISc team deduced that a critical protein produced by Salmonella, known as SopB, prevents both the fusion of SCV with lysosomes as well as the production of lysosomes, in a two-pronged approach to protect the bacterium. “[This] gives the upper hand to bacteria to survive inside macrophages or other host cells,” explains Ritika Chatterjee, former PhD student in MCB and first author of the study. The experiments were carried out on immune cell lines and immune cells extracted from mice models.

Image: Ritika Chatterjee

SopB acts as a phosphatase – it aids in removing phosphate groups from phosphoinositide, a type of membrane lipid. SopB helps Salmonella change the dynamics of the vacuole – specifically it alters the type of inositol phosphates in the vacuole membrane – which prevents the vacuole’s fusion with lysosomes.

A previous study from the same team had reported that the number of lysosomes produced by the host cells decreases upon infection with Salmonella. The researchers also found that mutant bacteria that were unable to produce SopB were also unable to reduce host lysosome numbers. Therefore, they decided to look more closely at the role that SopB was playing in the production of lysosomes, using advanced imaging techniques.

What they found was that SopB prevents the translocation of a critical molecule called Transcription Factor EB (TFEB) from the cytoplasm of the host cell into the nucleus. This translocation is vital because TFEB acts as a master regulator of lysosome production.

“This is the first time we deciphered that SopB can work in a dual manner – it changes the phosphoinositide dynamics of SCV and affects TFEB’s translocation into the nucleus. While other groups have already reported the function of SopB in mediating invasion in epithelial cells, the novelty of our study lies in identification of the function of SopB in inhibiting the vacuolar fusion with existing autophagosomes/lysosomes, and the second mechanism, which provides Salmonella with a survival advantage by increasing the ratio of SCV to lysosomes,” says Dipshikha Chakravortty, Professor at MCB and corresponding author of the study.

The researchers suggest that using small molecule inhibitors against SopB or activators of TFEB can help counter Salmonella infection.

In subsequent studies, the team plans to explore the role of another host protein called Syntaxin-17 whose levels also reduce during Salmonella infection. “How do the SCVs reduce the levels of Syntaxin-17? Do they exchange it with some other molecules, or do the bacteria degrade it? We [plan to] look into it next,” says Chakravortty.

REFERENCE:

Chatterjee R, Chaudhuri D, Gangi Setty SR, Chakravortty D, Deceiving the big eaters: Salmonella Typhimurium SopB subverts host cell xenophagy in macrophages via dual mechanisms, Microbes and Infection (2023).

CONTACT:

Dipshikha Chakravortty
Professor
Department of Microbiology and Cell Biology (MCB)
Indian Institute of Science (IISc)
Email: dipa@iisc.ac.in
Phone: 080-2293 2842
Lab website: https://mcbl.iisc.ac.in/dclab/

Ritika Chatterjee
Former PhD student
Department of Microbiology and Cell Biology (MCB)
Indian Institute of Science (IISc)
Email: ritikac@iisc.ac.in

NOTE TO JOURNALISTS:

a) If any of the text in this release is reproduced verbatim, please credit the IISc press release.
b) For any queries about IISc press releases, please write to news@iisc.ac.in or pro@iisc.ac.in.

30 May 2023

– Mohammed Asheruddin

With summer temperatures soaring, the spectre of water scarcity looms large. As a possible solution to increase the availability of clean, potable water, researchers at the Indian Institute of Science (IISc) have developed a novel thermal desalination system which can work using solar energy.

The most common methods for desalination are membrane-based reverse osmosis and thermal desalination. However, both consume a lot of energy.

Thermal desalination systems work by heating saltwater and then condensing the resulting vapour to obtain freshwater. But the energy required for evaporation is usually obtained from either electricity or combustion of fossil fuels. An environmentally friendly alternative is using solar stills in which solar energy is employed to evaporate saltwater in large reservoirs and the vapour that condenses on a transparent roof is collected. However, during condensation, a thin layer of water forms on the roof, reducing the amount of solar energy that can penetrate the reservoir and therefore the system’s efficiency.

As an alternative to such solar stills, the IISc team has developed a novel design for a solar-powered desalination unit that is more energy-efficient, cost-effective and portable, making it convenient to set up in areas with limited access to continuous electricity, explains Susmita Dash, Assistant Professor in the Department of Mechanical Engineering and corresponding author of the study published in Desalination.

The setup, designed by Dash and her PhD student Nabajit Deka, comprises a reservoir of saline water, an evaporator, and a condenser enclosed within an insulating chamber to avoid heat losses to the ambient air.

Experimental setup (Photo: Nabajit Deka)

Their system works by using solar thermal energy to evaporate a small volume of water imbibed or “wicked” into the evaporator, which has a textured surface. The wicking of liquid into the evaporator takes advantage of the capillary effect of microscale textures. This effect allows liquids to be drawn into narrow spaces of a porous material, much like water being absorbed by a sponge. Utilising this approach, instead of heating the entire liquid volume in the reservoir, results in a significant improvement in the system’s energy efficiency, says Dash.

The team etched tiny grooves on the surface of the evaporator, which is made of aluminium. Deka explains that they had to experiment with different combinations of groove dimension and spacing as well as surface roughness to determine the right pattern for efficient wicking.

The condenser – often overlooked in a majority of desalination studies, according to the researchers – is another key element of the solar desalination system. To prevent the formation of the water film during condensation, like in the solar stills, Dash and Deka fabricated a condenser with alternating hydrophilic and superhydrophilic surfaces. The water droplets condensing on the hydrophilic patterns are pulled towards the superhydrophilic region. This affinity of the condensed water to the superhydrophilic region enables the hydrophilic surface to become free for a fresh batch of condensate, explains Dash.

Schematic of a multistage solar thermal desalination system (Image: Nabajit Deka)

During condensation, some heat gets lost to the atmosphere. The researchers designed the system in such a way that this heat released during condensation is also trapped and utilised to heat up the imbibed saltwater in a different evaporator at the backside of the condenser, which reduces the amount of solar energy needed, and increases the efficiency of the system even more. The team also successfully connected multiple evaporator-condenser combinations in a series, resulting in a multi-stage solar desalination system. This system, if built in a footprint area of 1 m2, has the capacity to produce one litre of potable water every 30 minutes – at least twice as much as that produced by a traditional solar still of the same size.

Apart from seawater, the system can also work with groundwater containing dissolved salts as well as brackish water. It can be adjusted to align with the shifting positions of the sun during the day.

The researchers are currently working on scaling up the system and improving its durability, and increasing the volume of drinking water produced, so that it can be deployed for domestic and commercial use.

REFERENCE:

Deka N, Dash S, Multistage interfacial thermal desalination system with metallic evaporators, Desalination (2023).

CONTACT:

Susmita Dash
Assistant Professor
Department of Mechanical Engineering
Indian Institute of Science (IISc)
Email: susmitadash@iisc.ac.in
Telephone: +91 (80) 2293 2962
Lab website: https://sites.google.com/view/dashresearchlab

Nabajit Deka
PhD student
Department of Mechanical Engineering
Indian Institute of Science (IISc)
Email: nabajitdeka@iisc.ac.in

NOTE TO JOURNALISTS:

a) If any of the text in this release is reproduced verbatim, please credit the IISc press release.
b) For any queries about IISc press releases, please write to news@iisc.ac.in or pro@iisc.ac.in.

6 June 2023

–Malavika P Pillai (with input from authors)

The mystery of the unpredictable and heavy foaming in Bengaluru’s Bellandur lake has baffled scientists, regulators and citizens. Several theories have been put forth, and control measures taken, yet the foam continues to form year after year. A team from the Centre for Sustainable Technologies (CST), Indian Institute of Science (IISc), has been monitoring this foam continuously for the last four years in order to unravel this mystery.

One of the reasons why the foaming has puzzled scientists is because it counterintuitively increases only after heavy rains, which are supposed to dilute pollutants in the lake that may be causing the foaming. In a study published in Science of the Total Environment, the researchers have uncovered the reason behind this peculiarity.

The team highlights three factors that are key to this foaming. The first is untreated sewage that enters the lake. Because the lake is large, the sewage takes 10-15 days to disperse through the lake; during this time, a part of the organic material gets degraded in the absence of oxygen and settles down as sludge. As more and more sewage flows through the lake, surfactants in the sewage do not decompose and instead get loosely attached to the settled sludge, gradually increasing in concentration – in some cases, up to 200 times the original concentration entering the lake, points out Chanakya HN, Chief Research Scientist at CST and one of the authors of the study. “Imagine adding one full scoop of washing powder into a bucket of water; it will definitely foam given the right conditions,” he explains.

Foam buildup at main outlet after heavy rain (Photo: Chanakya HN)

The second factor is heavy rainfall that brings in large quantities of run-off from the city into the lake overnight. This high-volume inflow appears to churn up the surfactant-laden sludge, dislodge the accumulated surfactant from the sludge, and bring it back into solution, making it ready to foam. Deep inside the lake itself, there is little foam, because air bubbles do not form. However, as the water level in the lake rises due to rains, the excess water containing large concentrations of the surfactants spills over into the lake’s outlet to depths as high as 25 feet, trapping air bubbles which turn into foam. “This is an important phenomenon that converts the surfactant-laden water into foam,” says Lakshminarayana Rao, Associate Professor at CST and one of the authors.

In addition to these two factors, the researchers also suggest that suspended solids containing certain bacteria might be responsible for foam formation and stability – the mechanisms involved need to be validated through further experiments.

To study the foam formation, the researchers collected water samples from the lake, analysed various parameters, and recreated a lab model to track the changes in chemical composition of the surfactants across different regions of the lake as well as at different times of the year. “I had to go to the lake every month over the years to collect water and foam samples, and conduct experiments on them,” says Reshmi Das, PhD student at CST and first author of the study. She took the help of officials from the Bangalore Water Supply and Sewerage Board (BWSSB) and Bangalore Development Authority (BDA) to collect the samples.

The stable foam travels along a 10m deep valley up to a few kilometres before being dispersed (Photo: Chanakya HN)

Recent analysis by the team also suggests that a single type of surfactant commonly used in most of the household washing powders and shampoos plays a dominant role in driving this foaming.

In a typical sewage treatment plant, these surfactants are subject to biodegradation and most of them are removed. The authors propose that stopping the entry of untreated sewage into the lake is crucial to prevent the build-up of surfactants and sludge, their churning, and the resulting foaming at the outfall. They also suggest that wherever this is not immediately possible, removing the accumulated sludge in the polluted lakes – at least before the rains – as well as proper disposal of it can help address this burning issue.

REFERENCE:

Das R, Chanakya HN, Rao LN, Unravelling the reason for seasonality of foaming in sewage-fed urban lakes, Science of The Total Environment (2023).

CONTACT:

Reshmi Das
PhD student
Centre for Sustainable Technologies (CST)
Indian Institute of Science (IISc)
Email: reshmidas@iisc.ac.in

Chanakya HN
Chief Research Scientist
Centre for Sustainable Technologies (CST)
Indian Institute of Science (IISc)
Email: chanakya@iisc.ac.in
Phone: 080-2293 3046

Lakshminarayana Rao
Associate Professor
Centre for Sustainable Technologies (CST)
Indian Institute of Science (IISc)
Email: narayana@iisc.ac.in
Phone: 080-2293 2051
Lab website: https://www.plasmalabiisc.com/

NOTE TO JOURNALISTS:

a) If any of the text in this release is reproduced verbatim, please credit the IISc press release.

b) For any queries about IISc press releases, please wr

08 June 2023

– Harsha PM

Patients with diabetes have high blood glucose levels either because their pancreas does not produce sufficient insulin, or their body cells do not respond to signals from insulin that tell them to use up glucose. Current treatments, therefore, rely on supplying insulin bolus to such patients. However, recent studies have shown that fluctuations in the levels of other hormones such as somatostatin – also secreted by the pancreas – may be involved in the development of diabetes, something that has largely been overlooked so far.

“Changes in somatostatin secretion can be one of the first signs of diabetes,” explains Nikhil Gandasi, Assistant Professor at the Department of Developmental Biology and Genetics (DBG), Indian Institute of Science (IISc). In such a scenario, detecting the levels of somatostatin can therefore potentially help detect diabetes earlier.

In a study published in the International Journal of Molecular Sciences, Gandasi’s team, along with collaborators at the University of Gothenburg, Sweden, report the development of a novel assay that can detect secreted somatostatin. Somatostatin is secreted by specific cells of the pancreas, called delta cells. It is a master regulator of insulin and glucagon – another hormone that works hand-in-hand with insulin to maintain blood sugar levels.

The kit works like the standard Enzyme-Linked Immunosorbent Assay or ELISA which uses antibody-coated plates to identify the presence of antigens in a sample, similar to the COVID-19 rapid antigen test. The team used artificially synthesised somatostatin to test its binding against several commercially available antibodies, in order to identify the one that bound to it most efficiently, which they then used to develop the assay.

Using this assay, the researchers were able to detect the levels of somatostatin in pancreatic cells extracted from both mice and humans. In addition, they were able to measure the number of the delta cells that produce somatostatin in both human healthy and diabetic donor tissues. What they found was that the number of delta cells was drastically reduced in diabetic patients. “There are less number of delta cells in the diabetic patient, therefore we see less secretion of somatostatin,” says first author Lakshmi Kothegala, senior scientist at the University of Gothenburg, Sweden, and visiting scientist at IISc.

Currently, researchers rely on Radioimmunoassay (RIA) to detect somatostatin levels. But RIA uses radioactive materials and needs to be carried out under stringent safety conditions. Besides, RIA takes at least three days to complete, and can only be carried out in specialised labs, says Caroline Miranda, another first author and post-doctoral fellow at the University of Gothenburg. “Having a fully functional ELISA will mean a more practical method, with faster results,” she adds. The newly developed kit also requires only one-tenth of the volume of blood plasma sample needed for RIA.

The researchers are currently working with an industry collaborator to develop the kit into a simple handheld device that can eventually be mass-produced.

REFERENCE:

Kothegala L, Miranda C, Singh M, Krieger J-P, Gandasi NR, Somatostatin Containing δ-Cell Number Is Reduced in Type-2 Diabetes, International Journal of Molecular Sciences (2023).

CONTACT:

Nikhil Gandasi
Assistant Professor
Department of Developmental Biology and Genetics (DBG)
Indian Institute of Science (IISc)
Adjunct Faculty, Uppsala University, Sweden
Email: grnikhil@iisc.ac.in
Phone: +91-80-22933460

Lakshmi Kothegala
Senior Scientist, University of Gothenburg, Sweden
Visiting Scientist, DBG, IISc
Email: lakshmi.kothegala@gu.se

Caroline Miranda
Postdoctoral research fellow,
University of Gothenburg, Sweden
Email: caroline.miranda@gu.se

NOTE TO JOURNALISTS:

a) If any of the text in this release is reproduced verbatim, please credit the IISc press release.
b) For any queries about IISc press releases, please write to news@iisc.ac.in or pro@iisc.ac.in.

14 June 2023

– Narmada Khare

Alzheimer’s disease, a neurodegenerative disorder, results in memory loss and compromises cognitive abilities in many people beyond the age of 60. Currently used techniques to detect manifestations of the disease (MRI, PET, and CT scans) are complex, expensive, and often produce inconclusive results.

“Our goal was to find a reliable, cost-effective solution,” says Debasis Das, Assistant Professor in the Department of Inorganic and Physical Chemistry (IPC), Indian Institute of Science (IISc). In a study published in Analytical Chemistry, he and Jagpreet Sidhu, a CV Raman postdoctoral fellow in IPC, have designed a small molecular fluorogenic probe that can sense a specific enzyme linked to the progression of Alzheimer’s disease. Such a probe can easily be fabricated into a strip-based kit that may enable on-site diagnosis.

“Fluorogenic probes are not fluorescent by themselves, but upon reaction with a target enzyme, they become fluorescent,” explains Das. “Our target enzyme is Acetylcholinesterase (AChE).” Studies have shown that in the early stages of Alzheimer’s disease, AChE levels become imbalanced, thus making it a potential biomarker for the disease.

Brain cells or neurons secrete neurotransmitters – signalling molecules that instruct other cells to perform certain functions. Acetylcholine (ACh) is one such neurotransmitter; its levels in our nervous system are tightly controlled by enzymes like AChE, which breaks it down into two parts – acetic acid and choline. Current approaches determine AChE levels indirectly by measuring the levels of choline. They also often give confounding results because AChE has “sister enzymes” such as butyrylcholinesterase and cholinesterase that work on similar substrates, including ACh, says Das.

The team first analysed the crystal structures of the enzyme (AChE) and the substrate (ACh). Then, they designed a synthetic molecule that mimics ACh. The probe developed by the team has one structural element (quaternary ammonium) that interacts specifically with AChE, and another that binds to the active site in AChE and gets digested (just like natural ACh), giving out a fluorescent signal. The team tweaked the distance between the two elements to make it bind tightly to the enzyme. “In previous reports, people did not use this quaternary ammonium group. Because of this, they were not able to attain specificity and selectivity,” says Sidhu, who is the first author of the study.

A new fluorogenic probe was designed and synthesised for the specific detection of acetylcholinesterase, a crucial enzyme that hydrolyses the neurotransmitter acetylcholine and is linked to Alzheimer’s progression (Image: Tabish Iqbal)

To test the probe’s ability to be digested specifically by the enzyme, the team used commercially available AChE as well as lab-made human brain AChE expressed in bacteria. Although AChE has been extracted from the human brain, purified, and crystallised in the past, this is the first time that it has been purified in the active form after cloning and expressing it in a bacterial system, the researchers say.

In collaboration with Deepak Saini’s lab at the Department of Developmental Biology and Genetics, IISc, the team showed that the fluorogenic probe could also enter brain cells cultured in the lab and fluoresce upon contact with AChE.

“We now have a proof-of-concept and a lead. Our goal is to take it to translation, in an Alzheimer’s disease model. For this, we need to modify the probe,” says Das. Currently, the probe is UV-active, which can be harmful to tissues in high doses. “These modifications would lead to the development of near-infrared active probes, which would be safer for living cells and allow deep-tissue imaging. We are already quite close to doing this.”

Apart from Alzheimer’s disease, such a probe can also be used for other applications like detecting pesticide-related poisoning, as AChE can be inhibited by compounds used in some pesticides, Sidhu adds.

Jagpreet Sidhu and Debasis Das (Photo: Reshma Ramakrishnan)

REFERENCE:

Sidhu JS, Rajendran K, Mathew AB, Iqbal T, Saini DK, Das D, Acetylcholine Structure-Based Small Activatable Fluorogenic Probe for Specific Detection of Acetylcholinesterase, Analytical Chemistry (2023).

Das acknowledges Syngene International Limited, Saini acknowledges SERB, and Sidhu acknowledges CV Raman fellowship for supporting this work financially.

CONTACT:

Debasis Das
Assistant Professor
Department of Inorganic and Physical Chemistry (IPC)
Indian Institute of Science (IISc)
Email: debasisdas@iisc.ac.in
Phone: +91-80-2293 3002
Lab website: https://sites.google.com/view/ddlaboratory/home

Deepak K Saini
Professor
Department of Developmental Biology and Genetics (DBG)
Indian Institute of Science (IISc)
Email: deepaksaini@iisc.ac.in
Phone: +91-80-2293 2574

Jagpreet Sidhu
CV Raman Postdoctoral fellow
Department of Inorganic and Physical Chemistry (IPC)
Indian Institute of Science (IISc)
Email: jagpreets@iisc.ac.in

NOTE TO JOURNALISTS:

a) If any of the text in this release is reproduced verbatim, please credit the IISc press release.
b) For any queries about IISc press releases, please write to news@iisc.ac.in or pro@iisc.ac.in.