Macroinvertebrates are an important component of stream ecosystems and are a link in the transfer of material and energy from producers to top level consumers and also act as excellent bioindicators of stream health. This review discusses some of the factors which regulate the occurrence and distribution of stream macroinvertebrates namely water current, temperature, substrate, drainage basin land use/land cover, vegetation, pH of water, drought, flood, food, shade and stream geomorphology.

Global biodiversity losses have assumed the status of a crisis and as a part of it, many amphibian populations are declining. It is estimated that the current rate of extinction is greater than any known in the last 100,000 years. Recent studies have shown that nearly one-third of amphibian species are threatened. Amphibians are thought to be indicator species of overall environmental health, and understanding their declines may serve as a model for understanding species declines in general. The present review discusses the present state of knowledge about the complex problem of amphibian declines: the hypotheses which have been propounded, the remedial measures which have been proposed and the future directions for research in this important area.

Despite substantial investment in research and treatment options, diabetes mellitus remains a pressing public health concern with potential epidemic proportions globally. There are reports that by the end of 2040, 642 million people will be suffering from diabetes. Also, according to an estimation, 1.6 million deaths were caused directly by diabetes in 2016. Diabetes is a metabolic disorder characterized by impaired glucose regulation in the body due to the destruction of pancreatic β-cells or insulin resistance. Genetic propensity, unhealthy and imbalanced diet, obesity and increasing urbanization are the common risk factors for diabetes. Besides this, it has been reported that environmental pollutants like organic pesticides, heavy metals, and air pollutants act as strong predisposing factors for diabetes owing to their highly bio-accumulative nature. These pollutants disturb glucose homeostasis either by up-regulating or down-regulating the expression of diabetic marker genes like insulin (INS), glucokinase (GCK). Unfortunately, the molecular mechanism about the role of pollutants in causing diabetes is not very clear. This mechanistic review provides evidence of different environmental determinants including persistent organic pollutants (POPs), air pollutants, toxic metals, etc. in inducing diabetes and proposes a framework for the possible mechanisms involved. It also illuminates the current status and future challenges which will not only broaden our understanding but can also be a reasonable platform for further investigation.

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