Surbhi Sharma
Profile Url: surbhi-sharma
Researcher at Academy of Scientific and Innovative Research (AcSIR), CSIR Human Resource Development Centre (CSIR-HRDC)
The Journal of Experimental Biology, 2018-11-16
High fecundity, transparent embryos for monitoring the rapid development of organs and the availability of a well-annotated genome has made zebrafish a model organism of choice for developmental biology and neurobiology. This vertebrate model, a favourite in chronobiology studies, shows striking circadian rhythmicity in behaviour. Here, we identify novel genes in the zebrafish genome, which shows their expression in the zebrafish retina. We further resolve the expression pattern over time and assign specific novel transcripts to the retinal cell type, predominantly in the inner nuclear layer. Using chemical ablation and free run experiments we segregate the transcripts that are rhythmic when entrained by light from those that show sustained oscillations in the absence of external cues. The transcripts reported here with rigorous annotation and specific functions in circadian biology provide the groundwork for functional characterisation of novel players in the zebrafish retinal clock.
The circadian clock regulates vital cellular processes by adjusting the physiology of the organism to daily changes in the environment. Rhythmic transcription of core Clock Genes (CGs) and their targets regulate these processes at the cellular level. Circadian clock disruption has been observed in people with neurodegenerative disorders like Alzheimers and Parkinsons. Also, ablation of CGs during development has been shown to affect neurogenesis in both in vivo and in vitro models. Previous studies on the function of CGs in the brain have used knock-out models of a few CGs. However, a complete catalog of CGs in different cell types of the developing brain is not available and it is also tedious to obtain. Recent advancements in single-cell RNA sequencing (scRNA-seq) has revealed novel cell types and elusive dynamic cell states of the developing brain. In this study by using publicly available single-cell transcriptome datasets we systematically explored CGs-coexpressing networks (CGs-CNs) during embryonic and adult neurogenesis. Our meta-analysis reveals CGs-CNs in human embryonic radial glia, neurons and also in lesser studied non-neuronal cell types of the developing brain.
Though relatively little is understood of adaptation, physiological and metabolic changes of Stevia rebaudiana under exposure to salinity stress, it is hypothesized that exogenous application of potassium (K+) could elevates the salinity tolerance through ions homeostasis. Thus, an experiment was conducted with twenty treatment combinations comprising four salinity levels (irrigation with normal water as control and three level of NaCl at 40, 80 and 120 mM) and five different concentrations of KNO3 (0.0, 2.5, 5.0, 7.5, and 10.0 g L-1). Dry leaf yield was not negatively affected with mild salinity (40 mM). However, the detrimental effects were observed at moderate and higher salinity levels (80 and 120 mM). The uptakes of K+, Ca2+, and N were significantly reduced at higher salinity level, whereas accumulations of Na+ and Cl− ions in plant tissues were substantially increased. Proline content in leaf was also increased significantly (P≤0.05) in response to salt stress. Among the foliar application, KNO3 at 5.0 gL-1 registered significantly (P≤0.05) higher dry leaf yield compared with control. Exogenous application of K+ under moderate salinity stress maintained ion balance in cytosol, particularly K: Na. Thus, the salinity tolerance of stevia can be elevated to some extent through exogenous application of K+.