31 January 2024

The 42nd meeting of the Astronomical Society of India will be taking place this week at Indian Institute of Science (IISc), Bengaluru. The meeting is jointly organised by IISc, Indian Space Research Organisation (ISRO) and the JN Planetarium. There will be a press meet on January 31, 2024, at 6.30 pm at the JN Tata Complex, to discuss the upcoming astronomy initiatives and conference details. The formal inauguration of the event is set to take place at 9.30 am on February 1, 2024, at the JN Tata Main Auditorium, IISc.

Scientific discourses focussing on the sun, planets, black holes and beyond will be held from 31 January to 4 February, 2024. Popular events for citizens and school students will be offered throughout the week. About 750 astronomers are expected to be in attendance for the meeting.

Special attractions this year include the release of the Astronomy Vision – a document which includes the culmination of a nationwide exercise to imagine the future of cosmic exploration from India, a workshop on the recently launched AdityaL1 mission – India’s first space based solar observatory, plenary lectures highlighting India’s planetary exploration program and pulsar timing array initiatives. The ASI awards which will be given out during the inaugural function, recognises and honours the contributions of students, scientists and citizens to astronomy and astrophysics research as well as capacity building activities.

More details of the meeting are available at: https://astron-soc.in/asi2024.

A number of events have been separately planned for the common citizens and school students. The Public Outreach and Education Committee of the Astronomical Society of India is partnering with local organisers and astronomy industries to host popular lectures on themes ranging from space exploration to the role of astronomy in defining time and calendars. There are lectures planned on astrophotography, with a special showcase on the night skies of the Indian Himalayas and the need to preserve the heritage of the skies. Solar and night sky observation events have been organised and a star party is planned at the JN Planetarium.

A detailed agenda of events open to the public is available at: https://astron-soc.in/outreach/

CONTACT:

Local Organising Committee:
Banibrata Mukhopadhyay
Professor
Department of Physics
Indian Institute of Science (IISc)
Email: bm@iisc.ac.in

Astronomical Society of India (ASI): astron.soc.india@gmail.com

Office of Communications (OoC)
Indian Institute of Science (IISc)
Email: news@iisc.ac.in

NOTE TO JOURNALISTS:
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16-01-2024

–Pratibha Gopalakrishna

Ovarian cancer is dangerous because it often goes undetected until it has spread beyond the ovaries, and the symptoms can also be attributed to other conditions. Scientists believe that ageing can increase the spread of ovarian and other cancers, but the underlying mechanisms are not fully clear. Now, researchers at the Indian Institute of Science (IISc) have found that ovarian cancer cells can spread more easily in tissues that are senescent or aged because these tissues secrete a unique extracellular matrix that attracts the spreading cancer.

Senescent mesothelial matrix attracts ovarian cancer cells, aiding their adhesion and spread (Credit: Ramray Bhat, created on Biorender)

The researchers used a chemotherapy-induced senescent model to study this phenomenon. They first extracted tissues found in the lining of body cavities from mice models and exposed half of these tissues to chemotherapeutics that are used to treat cancer, pushing them to senescence – a state in which the cells stop replicating but don’t die. “What you might call in a body ageing, in a cell or tissue you would call it senescence,” explains Ramray Bhat, Associate Professor at the Department of Developmental Biology and Genetics (DBG) and corresponding author of the study published in Cellular and Molecular Life Sciences.

The team then exposed both young and aged mouse tissues and human tissue-like cell sheets to ovarian cancer cells. They used time-lapse imaging to tag the normal and cancer cells with different fluorescent markers so that they could be studied under a microscope for extended periods of time. “It’s slightly harder to image tissues when compared to cell lines as the latter has only one particular cell type growing,” explains Bharat Thapa, first author and former biology undergraduate student at IISc, now pursuing a PhD at Vanderbilt University, USA.

What they found was that the cancer cells chose to settle down more on the aged tissues; moreover, they settled closer to the aged normal cells in the cell sheets.

To figure out what was drawing the cancer cells to the aged cells, the team first wondered if they were being attracted to signalling molecules that were being secreted by the aged cells and diffusing over long distances. They built computer models to explore the interactions between the cancer cells and the aged cells.

What they found was surprising: It was not the diffusing molecules that were luring the cancer cells. It was proteins secreted by aged cells that settle down as the extracellular matrix (ECM) – the base on which the cells adhere and grow – that were calling the cancer cells. “The extracellular matrix is what was bringing the cancer cells there and allowing them to better attach near the aged cells and spread faster,” says Bhat.

The team also carried out experiments on human cell lines to replicate the predictions of the computer simulations. They noticed that the cancer cells stuck strongly to the extracellular matrix around the aged cells, and eventually cleared the aged cells away. They also noticed that the aged ECM had higher levels of proteins such as fibronectin, laminin and hyaluronan compared to the young cells’ ECM, which allowed the cancer cells to bind more strongly.

Based on their findings, the researchers suggest that this could potentially be one of the reasons why aged populations typically tend to have worse outcomes in cancer than younger populations. “The fact is that chemotherapy also induces senescence, and that senescence can make things worse,” says Bhat. “Appropriate use of chemotherapy could be very important in getting good outcomes in ovarian cancer.”

One way forward, adds Bhat, could be to focus on finding probes that can identify some of these matrix proteins, which can help predict where the cancer cells would get deposited in the tissues. Thapa also hopes that future studies will build a strong case for using senolytics – drugs that kill senescent cells – as a combination therapy with chemotherapeutics to tackle cancer progression.

REFERENCE:

Thapa BV, Banerjee M, Glimm T, Saini DK, Bhat R, The senescent mesothelial matrix accentuates colonization by ovarian cancer cells, Cellular and Molecular Life Sciences (2024).

The research was funded by the India Alliance DBT Wellcome Trust and the John Templeton Foundation.

CONTACT:

Ramray Bhat
Associate Professor
Department of Developmental Biology and Genetics (DBG)
Indian Institute of Science (IISc)
Email: ramray@iisc.ac.in
Phone: +91-80-22932764
Website: https://morphogenesisiisc.wixsite.com/home

Bharat Vivan Thapa
Former UG (Master of Science) student, Indian Institute of Science (IISc)
PhD student, Vanderbilt University
Email: bharat.v.thapa@vanderbilt.edu

NOTE TO JOURNALISTS:

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10 January 2024

– Mohit Nikalje

Since the beginning of the COVID-19 pandemic, Raghavan Varadarajan, Professor at the Molecular Biophysics Unit (MBU), Indian Institute of Science (IISc), and collaborators have been working on developing a heat-tolerant vaccine that can offer protection against different strains of SARS-CoV-2 – both current and future variants.

In a study published in npj Vaccines, they report the design of a synthetic antigen that can be manufactured as a potential COVID-19 vaccine candidate. They show that their vaccine candidate is effective against all current strains of SARS-CoV-2 and can be quickly adapted for future variants as well.

While current vaccines are proven to be effective against most SARS-CoV-2 strains, their efficacy has declined due to the virus’ rapid mutation. After analysing various proteins found in the virus, the researchers selected two parts of SARS-CoV-2’s spike protein – the S2 subunit and the Receptor Binding Domain (RBD) – for designing their vaccine candidate. The S2 subunit is highly conserved – it mutates much less than the S1 subunit, which is the target of most current vaccines. Scientists have also known that the RBD can provoke a strong immune response in the host. Therefore, the team created a hybrid protein called RS2 by combining these two components.

RS2 sequence conservation and protective efficacy
Top panel: Sequence conservation mapped onto a model of the RS2 molecule
Bottom Panel: Lung tissue sections from mice demonstrate superior protection conferred by RS2 against viral challenge
Credit: Nidhi Mittal

The researchers used mammalian cell lines to study the expression of the hybrid protein. “The protein showed very high levels of expression, and I [initially] thought that the experiment was not working properly,” says Nidhi Mittal, PhD student at MBU and first author of the study. This means, she explains, it can potentially be produced in large quantities.

The team then tested the effects of the protein in both mice and hamster models. They found that the hybrid protein triggered a strong immune response and provided better protection when compared to vaccines containing the whole spike protein.

The RS2 antigen can also be stored at room temperature for a month without the need for cold storage, unlike many vaccines on the market which require mandatory cold storage. This would make the distribution and storage of these vaccine candidates much more economical.

Varadarajan explains that his team began working on the vaccine even before the pandemic became widespread in India. “At that time, the Bill and Melinda Gates Foundation provided us funding and support,” he adds. Since 2000, Varadarajan’s team has been working on designing several viral vaccines, including those against AIDS and influenza. They have leveraged this expertise to design their current RS2-based COVID-19 vaccine candidate in collaboration with the startup Mynvax, that was, until recently, incubated at IISc.

According to the team, the vaccine candidate can be tailored to incorporate the RBD region of any new variant of SARS-CoV-2 that might emerge. Its high levels of expression and stability at room temperature can greatly reduce production and distribution costs, making it well suited for combating COVID-19.

REFERENCE:

Mittal N, Kumar S, Rajmani RS, Singh R, Lemoine C, Jakob V, Sowrabha BJ, Jagannath N, Bhat M, Chakraborty D, Pandey S, Jory A, Soundarya SAS, Kleanthous H, Dubois P, Ringe RP, Varadarajan R, Enhanced protective efficacy of a thermostable RBD-S2 vaccine formulation against SARS-CoV-2 and its variants, npj vaccines (2023).

CONTACT:

Raghavan Varadarajan
Professor
Molecular Biophysics Unit (MBU)
Indian Institute of Science (IISc)
Email: varadar@iisc.ac.in
Phone: 080-2293 3373
Website: http://mbu.iisc.ac.in/~rvgrp/home.html

Nidhi Mittal
PhD student
Molecular Biophysics Unit (MBU)
Indian Institute of Science (IISc)
Email: nidhimittal@iisc.ac.in

NOTE TO JOURNALISTS:

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05 January 2024

– Shloak Vatsal

Eaglenest Wildlife Sanctuary (Photo: Global Change Lab, CES)

Researchers at the Indian Institute of Science (IISc) have studied the effects of forest logging and climate change on bird communities in tropical mountains, by examining over 10 years of data. In a study published in Global Ecology and Conservation, the team used mist netting and bird ringing data to answer how the composition of the mid-elevation Eastern Himalayan understorey bird community changed in primary (undisturbed) forests as well as in logged forests.

Tropical montane forests are unique ecosystems that can start at about 150-200 m and reach up to 3,500 m high up on mountains around the world. They are critical centres of biodiversity. “In tropical mountains, each species has a particular niche where it is found. This restriction creates much more diversity in a small space,” explains Ritobroto Chanda, former Project Associate at the Centre for Ecological Sciences (CES), IISc, and corresponding author of the study.

Forest loss and climate change present major threats to these ecosystems. “Birds – and indeed much of the flora and fauna – of tropical mountain ranges are extremely temperature-sensitive and are responding to global heating rapidly. Also, most of the world’s terrestrial biodiversity is concentrated in tropical mountains,” says Umesh Srinivasan, Assistant Professor at CES and another author. However, very few studies have explored the joint influence of these threats.

A Chestnut-headed Tesia being ringed (Credit: Global Change Lab, CES)

The team found that many bird species have started shifting to higher elevations due to rising temperatures. Logged forests have higher average temperatures and lower humidity than primary forests, thus hastening the transition. Additionally, birds that are smaller in size seem to colonise these logged forests better because they can tolerate higher temperatures, while the density of larger bird species appears to be increasing in the primary forests.

The team collected data from the Eaglenest Wildlife Sanctuary, Arunachal Pradesh, situated in the biodiversity hotspot of Eastern Himalayas and home to over 500 bird species. The area saw intensive logging until 2002, and the logged regions have major differences compared to intact forests, making them ideal for the study. The support of the local communities is also critical to carry out such studies, Chanda says. “You have to stay in a wildlife sanctuary with no paved roads, no electricity, and no place to stay as such. We take our food with us, cook on a daily basis, make a makeshift camp and move around, and without the people’s support, it’s really not possible to continue this for a long time,” he emphasises.

Field crew (Photo: Global Change Lab, CES)

Each day, after setting up the mist nets, the team checked them every 20-30 minutes, weighed and labelled the birds, and released them immediately. Out of the 6,189 captured individuals from 130 species, the final analysis included 4,801 understorey insectivores – insect-eating birds that live under the canopy of large trees – belonging to about 61 species. The researchers focused on these birds because their niches are well defined and abundant data from the mist nets is available for them. Rare species were left out of the study to avoid skewed results.

What the team found was that logging can lead to the loss of large-bodied, old growth-dependent species, and decrease the overall biodiversity. Understorey insectivores, which are often found only in specific niches, are negatively influenced by logging and show steep declines in numbers. Logged forests also have lower densities of foliage-dwelling insects, reducing the resource availability for the birds. Since large species have higher energy requirements, this disproportionately reduces the abundance of large species.

The study highlights the need to safeguard primary forests in order to mitigate the effects of climate change. “Logging managers should ensure that undisturbed forests across large elevational gradients are protected,” says Srinivasan. He explains that this will allow species to shift their ranges upwards in response to climate change and maintain survival. “If species encounter degraded forest while they shift upwards, certain species will most likely go locally extinct.”

A Yellow-throated fulvetta with metal and colour rings (Photo: Micah Rai)

REFERENCE:
Chanda R, Rai S, Tamang B, Munda B, Pradhan DK, Rai M, Biswakarma A, Srinivasan U, Bird communities in a selectively logged tropical montane forest are dominated by small, low-elevation species, Global Ecology and Conservation (2023).

CONTACT:

Umesh Srinivasan
Assistant Professor
Centre for Ecological Sciences (CES)
Indian Institute of Science (IISc)
Email: umeshs@iisc.ac.in
Phone: +91-80-2293-2360
Website: https://ces.iisc.ac.in/?q=user/408

Ritobroto Chanda
Former Project Associate
Centre for Ecological Sciences (CES)
Indian Institute of Science (IISc)
Email: ritobrotochanda@gmail.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 write to news@iisc.ac.in or pro@iisc.ac.in

21^st January 2022

– Ranjini Raghunath

In recent years, a phenomenon called the quantum Hall effect has emerged as a platform for hosting exotic features called quasiparticles, with properties that could lead to exciting applications in areas like quantum computing. When a strong magnetic field is applied to a 2D material or gas, the electrons at the interface – unlike the ones within the bulk – are free to move along the edges in what are called edge modes or channels – somewhat similar to highway lanes. This edge movement, which is the essence of the quantum Hall effect, can lead to many interesting properties depending on the material and conditions. 

Left panel: Downstream (red lines) and upstream (dashed black lines). Middle panel: Schematic for noise measurement for “upstream” mode detection. Right panel: Noise is detected for fractional quantum Hall states with “upstream” modes whereas it remains zero for only downstream modes (Credit: Authors). 

For conventional electrons, the current flows only in one direction dictated by the magnetic field (‘downstream’). However, physicists have predicted that some materials can have counter-propagating channels where some quasiparticles can also travel in the opposite (‘upstream’) direction. Although these upstream channels are of great interest to scientists because they can host a variety of new kinds of quasiparticles, they have been extremely difficult to identify because they do not carry any electrical current.  

In a new study, researchers from the Indian Institute of Science (IISc) and international collaborators provide “smoking gun” evidence for the presence of upstream modes along which certain neutral quasiparticles move in two-layered graphene. To detect these modes or channels, the team used a novel method employing electrical noise – fluctuations in the output signal caused by heat dissipation.  

“Though the upstream excitations are charge-neutral, they can carry heat energy and produce a noise spot along the upstream direction,” explains Anindya Das, Associate Professor in the Department of Physics and corresponding author of the study published in Nature Communications. 

Quasiparticles are largely excitations that arise when elementary particles like electrons interact among each other or with matter around them. They are not truly particles but have similar particles like mass and charge. The simplest example is a ‘hole’ – a vacancy where an electron is missing in a given energy state in a semiconductor. It has an opposite charge to the electron and can move inside a material just like the electron does. Pairs of electrons and holes can also form quasiparticles which can propagate along the edge of the material.  

In previous studies, the researchers have shown that it might be possible to detect emergent quasiparticles like Majorana fermions in graphene; the hope is to harness such quasiparticles to eventually build fault-tolerant quantum computers. For identifying and studying such particles, detecting upstream modes which can host them is critical. Although such upstream modes have been detected earlier in gallium-arsenide based systems, none have been identified so far in graphene and graphene-based materials, which offer much more promise when it comes to futuristic applications.  

In the current study, when the researchers applied an electrical potential to the edge of two-layered graphene, they found that heat was transported only in the upstream channels and dissipated at certain “hotspots” in that direction. At these spots, the heat generated electrical noise that could be picked up by an electrical resonance circuit and spectrum analyser.  

The authors also found that the movement of these quasiparticles in the upstream channels was “ballistic” – heat energy flowed from one hotspot to another without any loss – unlike the “diffusive” transport observed earlier in gallium-arsenide based systems. Such a ballistic movement is also indicative of the presence of exotic states and features that could help build energy-efficient and fault-free quantum components in the future, according to the authors. 

REFERENCE: 

Kumar, R., Srivastav, S.K., Spånslätt, C. et al. Observation of ballistic upstream modes at fractional quantum Hall edges of graphene, Nature Communications, 13, 213 (2022).  

https://doi.org/10.1038/s41467-021-27805-4 

CONTACT: 

Anindya Das
Associate Professor
Department of Physics, Indian Institute of Science (IISc)
anindya@iisc.ac.in, dasanindy@gmail.com
+91-8022932525, +91-8023602600

NOTE TO JOURNALISTS:

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

28^th January 2022

– Karthika Kaveri Maiappan

 Sleep is fundamental for all animals; when an animal sleeps, the brain sorts and categorises memories, and restores its energy. Urban habitats like cities, however, can hamper an animal’s sleep quality and patterns due to higher temperatures, the presence of artificial structures like walls and buildings built by humans, and artificial light at night.   

 To adapt to these unusual conditions, urban peninsular rock agamas choose sleep sites that resemble their rural counterparts in the type of surface and the amount of light and heat received, a recent study by researchers at the Centre for Ecological Sciences (CES) at the Indian Institute of Science (IISc) has found. This study was published in Behavioral Ecology and Sociobiology. 

Is the city too hot for lizards (Credit: Maria Thaker)

Hot and cold – thermal image of a sleeping rock agama (Credit: Nitya Mohanty)

Nocturnal sampling for sleeping rock agamas in their natural habitat comprising boulder formations, outside Bangalore city (Credit: Tanmay Wagh)

A juvenile rock agama sleeping in rural Bangalore (Credit: Mihir Joshi)

While scientists have a reasonably good understanding of how animal brains work during sleep, how they sleep in the real world is not well known, says Maria Thaker, Associate Professor at CES and senior author of the study. “We know from human literature that certain conditions allow us to sleep better than others, and some disrupt our sleep. But animals live in the real world with all these conditions … and we wanted to understand where and how they sleep in the wild.” 

 The researchers compared lizard sleep sites in urban and rural habitats to look for differences in the types of surfaces the lizards were sleeping on, the extent of cover, temperature, and amount of light received.  

 “In the rural areas that are undisturbed, we scanned all the rocks, boulders, the ground, and shrubs to look for sleeping lizards. But in [urban] Bangalore, we would go into people’s backyards, because these lizards occupy empty lots or undeveloped plots, where there would be some concrete blocks that they use,” says Nitya Mohanty, first author of the study. Poking around in neighbourhoods at night with headlights and fancy camera equipment often drew a lot of attention from people and the police, and the team had to explain what they were doing to the public on several occasions, he adds.  

 Since urban habitats pose differences in terms of structure and more illumination at night as compared to rural areas, lizards would have to cope somehow, points out Thaker. “One way is to just sleep under these conditions. Or they can cope in another way, by finding conditions that closely match the wild as much as possible. What we found is somewhere in between the two.” 

 The team found that the lizards tend to pick structures that mimicked those in their natural habitat – they were more likely to sleep in rough concrete blocks that resembled their rocky sleep sites in the wild. The temperatures of both urban and rural sleep sites were also found to be similar. Urban sleep sites, however, were nine times more likely to be sheltered and covered as compared to rural sites, and this helped address the light problem in urban areas. This indicates that the lizards try to mitigate urban stressors by being flexible in their sleep site choices, and end up picking sites that resemble their rural sites. 

 Studying animals coping with anthropogenic environments is very important, according to Thaker. “The world is changing, and it is going to continue to change. So, if we know what it is that [other organisms] require to live here, then we can make some choices of our own to help keep them here.”

 REFERENCE

Mohanty NP, Joshi M & Thaker M, Urban lizards use sleep sites that mirror the structural, thermal, and light properties of natural sites. Behav Ecol Sociobiol, 2021, 75, 166. https://doi.org/10.1007/s00265-021-03101-5 

https://link.springer.com/article/10.1007%2Fs00265-021-03101-5#citeas 

 CONTACT 

Maria Thaker 
Associate Professor 
Centre for Ecological Sciences (CES) 
Indian Institute of Science (IISc) 
mthaker@iisc.ac.in 
 
Nitya Prakash Mohanty 
Postdoctoral fellow 
Centre for Ecological Sciences (CES)
Indian Institute of Science (IISc) 
nityamohanty@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. 

9^th January 2023

Axis Bank, India’s third-largest private sector bank, has signed a Memorandum of Understanding (MoU) with the Indian Institute of Science (IISc), Bengaluru, to establish a Centre for Mathematics and Computing at the Institute.

The Axis Bank Centre for Mathematics and Computing is India’s first comprehensive Academic Research Centre on Mathematics and Computing. It will play a vital role in building the nation’s future as many contemporary and futuristic areas such as Artificial Intelligence and Data Science rely on the foundations of mathematics and computing.

Commenting on the occasion, Prof Govindan Rangarajan, Director, IISc, said, “We thank Axis Bank for partnering with us in our commitment to excellence in research and innovation. Mathematics and Computing are at the core of critical disciplines like Computational Fluid Dynamics, Computational Biology, Quantum Computing, Precision Medicine, Digital Health, Climate Science, Materials Genomics, Cybersecurity, AI, ML, and Data Science. The Axis Bank Centre for Mathematics and Computing will provide a platform for exploring and advancing research and innovation in the above areas. The state-of-the-art facility will also serve as a training ground for the next generation of leaders in these fields, offering a range of educational and professional development opportunities for students and faculty. We are confident that the Centre will play a key role in shaping the future of research and technology.’’

Underlining the importance of the Centre, Amitabh Chaudhry, MD & CEO, Axis Bank, said, “It is an extremely proud moment for us to be part of IISc’s journey, while they are building one of the largest, dedicated Centres for Mathematics and Computing. The higher education ecosystem is a space that is constantly evolving, especially post Covid, and India has huge potential to stand out as a global hub for new-age, innovative and quality education. For us, this is one small way to play our part in supporting and nurturing the future generations of the country.”

Spread over 1.6 lakh square feet of space, the Centre will have state-of-the-art labs and programmes that will benefit faculty and students from more than twenty departments of IISc. The Centre will host the new IISc BTech programme in Mathematics & Computing and the ongoing Interdisciplinary PhD programme in Mathematical Sciences. It is expected that over 500 engineers and scientists will benefit from the Centre every year.

Contact:

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

About Axis Bank:

Axis Bank is the third largest private sector bank in India. Axis Bank offers the entire spectrum of services to customer segments covering Large and Mid-Corporates, SME, Agriculture and Retail Businesses. With its 4,760 domestic branches (including extension counters) and 16,043 ATMs across the country as on 30th September 2022, the network of Axis Bank spreads across 2,676 cities and towns, enabling the Bank to reach out to a large cross-section of customers with an array of products and services. The Axis Group includes Axis Mutual Fund, Axis Securities Ltd., Axis Finance, Axis Trustee, Axis Capital, A.TReDS Ltd., Freecharge and Axis Bank Foundation. For further information on Axis Bank, please refer to the website: https://www.axisbank.com

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10^th January 2023

– Shrivallabh Deshpande

A new study from the Indian Institute of Science (IISc) sheds light on how blackbucks in India have fared in the face of natural and human-induced challenges to their survival. The work, among the first of its kind in its scope, involved analysing the genetic profiles of blackbucks found across the country.

An adult male blackbuck (left) and a pair of female blackbucks with a suckling fawn (right). Credits: Ananya Jana

Increased human activities like indiscriminate cutting of trees and building dams across rivers have sliced up natural landscapes. These changing landscapes are restricting animal species to smaller areas, and preventing them from moving to farther regions in order to find new mates, a factor that is crucial for maintaining their genetic diversity. “We need genetic diversity to sustain a population because if you have genetic diversity, the population is more adaptable to changing environments,” explains Praveen Karanth, Professor at the Centre for Ecological Sciences (CES), IISc and senior author of the study published in Conservation Genetics.

The blackbuck is found only in the Indian subcontinent. Males have corkscrew-shaped horns and black-to-dark brown coats, while the females are fawn-coloured. The animals are mainly seen in three broad clusters across India that pertain to the northern, the southern, and the eastern regions. This geographic separation as well as dense human habitation between the clusters would be expected to make it difficult for them to move from one location to another. “We went in with the idea that these populations might be genetically constricted, and going forward, they may be in danger of getting incurring inbreeding depression [decreased biological fitness because of inbreeding],” recalls Ananya Jana, a former PhD student from CES and first author of the study.

Innumerable blackbucks dotted across rolling grasslands. Only few such habitats continue to thrive in India. Credits: Ananya Jana

Karanth and Jana collected faecal samples of blackbucks froCredits: Ananya Janam 12 different locations spread across eight states of India. The researchers tracked the animals on foot and in vehicles from a distance to collect the samples. When they returned to the lab, they extracted and sequenced the DNA from the faecal samples to study the genetic makeup of blackbucks, and deployed computational tools to map the geographic locations with the genetic data. The team also used simulations to trace how the three present-day clusters may have evolved from their common ancestor.

What they found was that an ancestral blackbuck population first split into two groups: the northern and the southern cluster. The eastern cluster – even though geographically close to the northern cluster – seems to have emerged from the southern cluster. “This was indeed a very surprising result,” adds Karanth. Next, the team found that despite all odds, male blackbucks appear to disperse more than expected, thus contributing to geneflow in this species. Females, on the other hand, appear to stay largely within their native population ranges, which the researchers inferred from unique mitochondrial signatures in each population. The data also showed an increasing trend in blackbuck population numbers as compared to the recent past.

Herds of blackbucks browsing in agricultural fields. Blackbucks are also seen in such human-dominated landscapes, albeit in relatively smaller groups. Such areas also face additional challenges of human-wildlife conflicts. Credits: Ananya Jana

“So, [it] looks like this species has managed to survive in a human-dominated landscape,” notes Karanth. In future studies, the researchers plan to unravel the blackbucks’ secrets to surviving in the face of human-induced threats to their landscape, by studying changes in their DNA and gut microbiome. Such studies could provide better insight into their conservation.

REFERENCE:

Jana A, Karanth KP, Not all is black and white: Phylogeography and population genetics of the endemic blackbuck (Antilope cervicapra), Conservation Genetics (2022).

https://doi.org/10.1007/s10592-022-01479-x

CONTACT:

K Praveen Karanth
Professor
Centre for Ecological Sciences (CES)
Indian Institute of Science (IISc)
Email: karanth@iisc.ac.in
Phone: 080-22933105

Lab website: https://praveenkaranth.weebly.com/

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12^th January 2023

– Narmada Khare

In two recent studies, researchers at the Indian Institute of Science (IISc) and Unilever have collaborated to develop computational models of bacterial cell walls that can speed up the screening of antimicrobials – molecules which can kill disease-causing bacteria.

Schematic illustration of surfactant molecules interacting with the bacterial peptidoglycan cell wall. The greater the tendency for surfactants to form aggregates, the lower is bacterial kill efficacy. Credit: Pradyumn Sharma-

Each bacterial cell is enveloped by a cell membrane, which is in turn surrounded by a cell wall. Some bacteria like Escherichia coli (E. coli) are Gram-negative – their cell walls contain a layer of peptide-sugar complexes called peptidoglycans and an outer lipid membrane. Others such as Staphylococcus aureus (S. aureus) are Gram-positive – their cell walls only have several layers of peptidoglycans.

Antimicrobials kill bacteria either by disrupting the cell wall’s lipid membrane and destabilising the peptidoglycan layer, or by translocating through the cell wall layers and disrupting the cell membrane inside. However, the actual mechanisms of interaction between antimicrobial molecules and these cellular barriers are poorly understood. “The cell envelope is a big part of this puzzle, and it is often overlooked,” says Pradyumn Sharma, a former PhD student at the Department of Chemical Engineering (CE), IISc, and one of the authors.

In one study, the team created an ‘atomistic model’, a computer simulation that recreates the structure of the cell wall down to the level of individual atoms. They incorporated parameters such as the sizes of sugar chains in the peptidoglycans, the orientation of peptides, and the distribution of void size.

“The structure of the peptidoglycan layer is semi-permeable, because nutrients and proteins that bacteria need, have to pass through,” explains Ganapathy Ayappa, Professor at CE and corresponding author. These are the same voids that the antimicrobials also pass through. Rakesh Vaiwala, a Research Associate at CE and one of the authors, adds that their team is the first to propose a comprehensive molecular model of the cell wall for S. aureus.

Using the supercomputing facility at IISc, the team tested the effectiveness of their model with several known antimicrobials. One of these, melittin, a short peptide, binds with higher efficiency to the E. coli cell wall than that of S. aureus. The researchers found that melittin interacts with peptides involved in a process called transpeptidation in peptidoglycan biosynthesis, and can potentially disrupt cell wall integrity. Thymol, a naturally occurring small molecule, translocated rapidly through the whole stack of peptidoglycans in the cell wall of S. aureus.

In the other study, the team used their model to compare the movement of different surfactant molecules through the peptidoglycan layer in E. coli. Like detergents, surfactants have a water-loving ‘head’ attached to a water-avoiding ‘tail’ chain. The team showed for the first time the link between the length of the tail and antimicrobial efficacy of surfactants. Surfactants like laurate with shorter chains translocated more efficiently than longer chain oleate. This was corroborated by experiments carried out by scientists in the Unilever team, which showed that shorter chain surfactants killed bacteria at a higher rate than surfactants with longer chains.

The team also collaborated with Jaydeep Kumar Basu, Professor in the Department of Physics, to create vesicles composed of E. coli extract and observed their interaction with surfactants under a microscope. The vesicles were found to burst open at a much faster in the presence of laurate compared to oleate.

“The goal with Unilever is to facilitate rapid screening of molecules using the computational models we have developed, to narrow down the search for potential antimicrobials to a smaller subset of molecules which can be tested in the laboratory,” explains Ganapathy Ayappa.

REFERENCES:

Sharma P, Vaiwala R, Parthasarathi S, Patil N, Verma A, Waskar M, Raut JS, Basu JK, Ayappa KG, Interactions of surfactants with the bacterial cell wall and inner membrane: Revealing the link between aggregation and antimicrobial activity, Langmuir (2022).

https://doi.org/10.1021/acs.langmuir.2c02520

Vaiwala R, Sharma P, Ayappa KG, Differentiating interactions of antimicrobials with Gram-negative and Gram-positive bacterial cell walls using molecular dynamics simulations, Biointerphases (2022).

https://doi.org/10.1116/6.0002087

CONTACT:

K Ganapathy Ayappa

Professor, Department of Chemical Engineering

Indian Institute of Science (IISc)

Email: ayappa@iisc.ac.in

Phone: +91-80-2293 2769

Lab website: https://kgalabiisc.wixsite.com/kgalab

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