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.