Monday, 23 April 2018

Tinkering With Root Hair May Help Boost Crop Yields

Once roots sense low availability of phosphate in the soil, the information is communicated to the plant which then signals back use of auxin to roots, in order to stimulate root hairs to grow longer and capture phosphate.

(Dr. Jitender Giri and Bipin K. Pandey)

Have you ever wondered how a plant is able to sense nutrients in the soil. The answer lies in the root design. Plants have the capability to change angle and length of their roots as well as hair-like extensions on roots for absorbing nutrients from soil. 

Now researchers are exploring mechanisms adopted by plants to survive in low phosphate soils and figuring out if they can develop better strategies for plants to deal with poor water availability and low soil minerals. 

In a collaborative study, researchers at the National Institute of Plant Genome Research (NIPGR) here have discovered in rice plant that production and transport of a hormone, auxin, in root hair zone triggers elongation of root hair under low phosphate conditions. The results of the study have been published in journal Nature Communications.

Phosphate is an important nutrient for plant growth and development. Researchers say once roots sense low availability of phosphate in the soil, the information is communicated to the plant which then signals back use of auxin to roots, in order to stimulate root hairs to grow longer and capture phosphate. 

The study explains how auxin serves as an important signal for phosphate status in the root. A specific gene, OsAUX1, mobilizes auxin in the region of root where it signals hair elongation when roots encounter low soil phosphate. 

Root hairs help to absorb phosphate and water from soil. The root hairs elongate to increase surface area to capture scarce nutrients such as phosphate under low soil phosphate conditions. 

“Green revolution helped almost triple yields of major crops like rice and wheat. However, it was highly dependent on chemical fertilizers like phosphate and urea. India imports almost 90 percent of raw material for producing phosphate fertilizers. This inspired us to engineer plant roots for better nutrient acquisition,” Dr. Jitender Giri told India Science Wire. Bipin K. Pandey, a member of the team, explained that the study had revealed big role of tiny cellular extensions - root hairs- in nutrient acquisition from poor soils.

In another study published in the same journal, the research group has used Arabidopsis, a model plant, to further explore the phenomenon. It has been seen that when auxin synthesis or its transport to root tissues is disrupted, plant shows poor root hair elongation in response to low external phosphate conditions.

This research teams included members from NIPGR (India) , University of Nottingham (UK), Shanghai Jiao Tong University, (China), CIRAD (France), Swedish University of Agricultural Sciences (Sweden), University of Aberdeen (UK), JIRCAS (Japan), James Hutton Institute (UK), Rothamsted Research (UK), The Pennsylvania State University, (USA) and University of Adelaide (Australia). The research work at NIPGR was funded by the Department of Biotechnology (DBT).

Reference:
https://www.nature.com/articles/s41467-018-03850-4
https://www.nature.com/articles/s41467-018-03851-3

Wednesday, 18 April 2018

Glycogen In Neurons Of Degenerating Brains Is Beneficial: Study

A team of Indian scientists has figured out that glycogen in neurons actually has a protective role in patients with neurodegenerative disorders like Alzheimer’s and Huntington’s.




(Dr. S. Ganesh and his team members)


Healthy neurons do not store glycogen – the main source of energy storage for cells – while they do possess the machinery for glycogen synthesis in an inactive state. At the same time, neurons in degenerating brains are known to accumulate glycogen. A team of Indian scientists has figured out that glycogen in neurons actually has a protective role in patients with neurodegenerative disorders like Alzheimer’s and Huntington’s.

For long, scientists have been trying to find the specific role of glycogen in neurons, especially in brain diseases like Huntington’s, Lafora, Alzheimer’s etc. with some believing it be neurotoxic. The new study led by Prof. Subramaniam Ganesh of Indian Institute of Technology, Kanpur (IIT-K) suggests that glycogen has a protective role in neurons of patients suffering from neurodegenerative disorders.

Glycogen synthetic machinery in healthy neurons usually remains in an inactive state. In this machinery, an enzyme called glycogen synthase catalyzes the formation of glycogen. Using cellular and animal models of Huntington’s disease, the researchers have shown that high level of cytotoxic mutant Huntingtin protein triggers more glycogen synthesis in neurons by activating glycogen synthase. They observed that increased level of glycogen synthase protects neurons from the cytotoxicity of the mutant Huntingtin protein.

“Our findings establish that glycogen synthase is required for neurons to survive during stress. We also show that glycogen thus synthesized prevents aggregation of abnormal proteins, and helps in their clearance. These findings might open up new avenues of therapeutic interventions,” explained Dr. Ganesh.

The activation of glycogen synthase is harmful to healthy and happy neurons, and this may explain why glycogen granules are not seen in normal neurons. This means glycogen accumulation in degenerating brain could possibly represent a failed attempt of neurons to survive during the stress. “Our work establishes the neuroprotective role of glycogen synthase in Huntington’s disease models and thus discovers a previously unknown function of glycogen synthase in neuronal physiology”, he added.

“It is an important finding on the protective role of glycogen synthase in neurodegenerative diseases which may have translational relevance,” commented Prof. Sathees C. Raghavan from Indian Institute of Science, who is not connected with this study.

“These findings may open exciting possibilities for developing new therapeutic approaches for the neurodegenerative diseases which are becoming serious health issues in human populations in recent times,” said Prof. S. C. Lakhotia from Banaras Hindu University, who is not a part of this study.

The study has been published in journal Cell Death and Disease. The research team included Anupama Rai, Pankaj K. Singh, Virender Singh, Rohit Mishra, Ashwani K. Thakur, and Subramaniam Ganesh (IIT-Kanpur); Vipendra Kumar, Nihar R. Jana (National Brain Research Centre, Manesar); Anita Mahadevan, Susarla K. Shankar, (NIMHANS, Bengaluru). This research work was funded by Department of Biotechnology. (India Science Wire)

Journal Ref.: 

Thursday, 12 April 2018

Scientists Shed Light On Cancer Risk Associated With Epigenetic Changes During Aging

To be able to predict aging-related cancer risks, researchers are trying to identify those genes which undergo the most epigenetic changes during normal aging and in early tumor development.


(Research team members)


The new science of Epigenetics has enabled us to track, how our lifestyle and surroundings affect the behavior of genes in our body, without altering the underlying DNA sequence (commonly called ‘mutations’).These epigenetic changes may stop aged cells and damaged cells from forming any new cells–akin to forced retirement, scientifically known as senescence, thereby preventing chances of cancer. However unusual epigenetic changes might help rogue cells to escape senescence and steer towards formation of tumors.

Now, to be able to predict aging-related cancer risks, researchers are trying to identify those genes which undergo the most epigenetic changes during normal aging and in early tumor development.

In a collaborative study, a team of researchers from India and USA (Dr.Subhojit Sen of University of Mumbai and Dr. Hariharan Easwaran of John Hopkins University, USA) have identified two sets of genes: one that may help human cancer cells to progress by rejecting forced retirement or senescence due to unusual DNA methylation, while a different set which might be responsible for cancers from normally aging cells. The results of this study have been published in the Journal ‘Cancer Cell’.

In this study, researchers have performed experiments on mice and cells from human skin samples. To analyze epigenetic changes, they observed patterns of DNA methylation, a process by which cells add tiny methyl chemical groups to a beginning region of a gene's DNA sequence, thereby dictating how that gene is used.

“Some groups have suggested that epigenetic changes may promote tumour formation. It was puzzling us-- how epigenetic changes occurring in the tumour-protective process of senescence may also promote formation of tumours ?. Hence we investigated the differences in epigenetic changes that occur in both events,”said Dr. Hariharan Easwaran.

The authors observed that although the process of DNA methylation appeared similar for both senescent and tumours cells, the genes that got methylated and the way it occurred were different between the two. They found that DNA methylation in senescent cells occurred in metabolic process related genes and appeared to be programmed and reproducible. On the other hand, in tumour cells, methylation occurred in growth related genes and appeared to be relatively random.

Classically, environmental stresses like smoking, harmful diets or lifestyle choices were thought to cause cancer mainly through DNA mutations. Recent studies have suggested that environmental stresses and carcinogens can also induce these types of unusual epigenetic changes. “Thus it is important to realize that these exposures impact our genomes in multiple ways - both genetic and epigenetic - all of which may synergize in inducing tumour formation,” added Dr. Easwaran.

“Next, we will explore strategies for determining age-associated risk of tumor development. It may eventually lead to biomarker development which might help us detect these changes very early on, even in healthy individuals,” said Dr. Easwaran

“This happens to be the first or at least initial evidence to clearly demonstrate differences in DNA methylations in terms of target genes. Successful replication of these results may help in deciding whether well-defined methylated genes can be developed as biomarkers for cancer risk assessment,” said Prof. Girish B. Maru, ACTREC, Mumbai, a cancer researcher who is not connected with this study.

Besides Dr. Easwaran and Dr. Subhojit Sen, the research team included many researchers from Johns Hopkins University and the USA’s National Institutes of Health.

Journal Ref.: DNA Methylation Patterns Separate Senescence from Transformation Potential and Indicate Cancer Risk