Role of gut symbionts of insect pests: A novel target for insect-pest control.

Insects possess beneficial and nuisance values in the context of the agricultural sector and human life around them. An ensemble of gut symbionts assists insects to adapt to diverse and extreme environments and to occupy every available niche on earth. Microbial symbiosis helps host insects by supplementing necessary diet elements, providing protection from predators and parasitoids through camouflage, modulation of signaling pathway to attain homeostasis and to trigger immunity against pathogens, hijacking plant pathways to circumvent plant defence, acquiring the capability to degrade chemical pesticides, and degradation of harmful pesticides. Therefore, a microbial protection strategy can lead to overpopulation of insect pests, which can drastically reduce crop yield. Some studies have demonstrated increased insect mortality via the destruction of insect gut symbionts; through the use of antibiotics. The review summarizes various roles played by the gut microbiota of insect pests and some studies that have been conducted on pest control by targeting the symbionts. Manipulation or exploitation of the gut symbionts alters the growth and population of the host insects and is consequently a potential target for the development of better pest control strategies. Methods such as modulation of gut symbionts via CRISPR/Cas9, RNAi and the combining of IIT and SIT to increase the insect mortality are further discussed. In the ongoing insect pest management scenario, gut symbionts are proving to be the reliable, eco-friendly and novel approach in the integrated pest management.

Modulation of cell surface architecture in gastrulating chick embryo in response to altered fibroblast growth factor (FGF) signaling.

Gastrulation is a fundamental process that results in formation of the three germ layers in an embryo. It involves highly coordinated cell migration. Cell to cell communication through cell surface and the surrounding molecular environment governs cell migration. In the present work, cell surface features, which are indicative of the migratory status of a cell, of an early gastrulating chick embryo were studied using scanning electron microscopy. The distinct ultrastructural features of cells located in the various regions of the epiblast are described. Differences in the surface features of cells from distinct embryonic regions indicate differences in their migratory capacities. Further, the dynamic nature of these cell surface features by their response to altered fibroblast growth factor (FGF) signaling, experimentally created by using either excess FGF or inhibition of FGF signaling are demonstrated.

The heart forming region of early chick embryo is an alternative source of embryonic stem cells.

In early chick embryo, the precardiac cells reside within distinct groups of mesodermal cells known as presumptive heart forming regions (HFRs). HFRs are located on the lateral sides of the Hensens node. In an effort to study fate of HFRs in isolation, HFRs were excised from early gastrulating chick embryos and cultured in vitro. A very small proportion of HFRs from 18 h incubated embryos differentiated into beating cardiomyocytes whereas about 43% of HFRs from embryos incubated for longer durations (20, 23 and 28 h) showed beating activity. The potential of HFRs, from 18 h incubated embryos, to differentiate into cardiomyocytes increased significantly in presence of Hensens node. About one third of the HFR cells underwent spontaneous differentiation into adipocytes in culture. Simultaneously, some of the cells derived from HFRs exhibited alkaline phosphatase (AP) activity indicating presence of stem cells in the culture. HFR cells were positive for vimentin indicating their mesenchymal origin. FGF supplement increased the proportion of AP-positive cells in a dose dependent manner. The present study demonstrates that HFRs can serve as a source of mesenchymal stem cells which can be gainfully employed for various purposes. The results also suggest that even though the in vitro cultured HFRs from 18 h incubated HH stage 4 chick embryo retain the potential to undergo cardiac differentiation, certain instructive signals from Hensens node may reinforce the fate.