02141nas a2200169   4500008004100000245010600041210006900147260000800216300001400224490000700238520150200245100002401747700002601771700002601797700002101823856012701844       2017                        eng d00aExploring the role of GS-GOGAT cycle in microcystin synthesis and regulation - a model based analysis0 aExploring the role of GSGOGAT cycle in microcystin synthesis and  cDEC  a2603-26140 v133 aToxic cyanobacteria blooms populate water bodies by consuming external nutrients and releasing cyanotoxins that are detrimental for other aquatic species, producing a significant impact on the plankton ecosystem and food web. To exercise population-level control of toxin production, understanding the biochemical mechanisms that explain cyanotoxin regulation within a bacterial cell is of utmost importance. In this study, we explore the mechanistic events to investigate the dependence of toxin microcystin on external nitrogen, a known regulator of the toxin, and for the first time, propose a kinetic model that analyzes the intracellular conditions required to ensure nitrogen dependence on microcystin. We hypothesize that the GS-GOGAT cycle is manipulated by variable influx of different intracellular metabolites that can either disturb or promote the balance between the enzyme microcystin synthetase and substrate glutamate to produce variable microcystin levels. As opposed to the popular notion that nitrogen starvation increases microcystin synthesis, our analyses suggest that under certain intracellular metabolite regimes, this relationship can either be completely lost or reversed. External nitrogen can only complement the conditions fixed by intracellular glutamate, glutamine and 2-oxoglutarate. This mechanistic understanding can provide an experimentally testable hypothesis for exploring the less-known biology of microcystin synthesis and designing specific interventions.1 aBanerjee, Swarnendu1 aSubramanian, Abhishek1 aChattopadhyay, Joydev1 aSarkar, Ram, Rup  uhttps://library.ncl.res.in/content/exploring-role-gs-gogat-cycle-microcystin-synthesis-and-regulation-model-based-analysis02181nas a2200229   4500008004100000022001400041245006000055210006000115260000800175300001000183490000800193520149500201653001601696653002701712653002101739653001301760653001801773100002401791700002101815700002601836856008901862       2019                        eng d  a0022-519300aEffect of copper contamination on zooplankton epidemics0 aEffect of copper contamination on zooplankton epidemics  cMAY  a61-740 v4693 a<p>Infectious disease and chemical contamination are increasingly becoming vital issues in many ecosystems. However, studies integrating the two are surprisingly rare. Contamination not only affects the inherent host-resource interaction which influences the epidemic process but may also directly affect epidemiological traits via changes in host's behaviour. The fact that heavy metal such as copper is also an essential trace element for organisms, further increase complexity which make predicting the resultant effect of contamination and disease spread difficult. Motivated by this, we model the effect of copper enrichment on a phytoplankton-zooplankton-fungus system. We show that extremely deficient or toxic copper may have a destabilizing effect on the underlying host-resource dynamics due to increased relative energy fluxes as a result of low host mortality due to fish predation. Further, on incorporating disease into the system, we find that the system can become disease-free for an intermediate range of copper concentration whereas it may persist for very less copper enrichment. Also, we predict that there may exist vulnerable regions of copper concentration near the toxic and deficient levels, where the parasite can invade the system for a comparatively lower spore yield. Overall, our results demonstrate that, the effect of contamination may be fundamental to understanding disease progression in community ecology. (C) 2019 Elsevier Ltd. All rights reserved.</p>10aBistability10aChemical contamination10aDaphnia-parasite10aHormesis10aHost-resource1 aBanerjee, Swarnendu1 aSarkar, Ram, Rup1 aChattopadhyay, Joydev  uhttps://library.ncl.res.in/content/effect-copper-contamination-zooplankton-epidemics