Biology subjects

Raman, D.

Publications and source records attributed to Raman, D..

3 recordsLinked to original sources

bioRxiv2022

How cerebellar architecture facilitates rapid online learning

SO_SCPLOWUMMARYC_SCPLOWThe cerebellum has a distinctive architecture in which inputs undergo a massive size expansion in dimensionality in early layers. Marr and Albuss classic codon theory and more recent extensions1-4 argue that this architecture facilitates learning via pattern separation. The essence of this idea is that sparsely active clusters -- codons-- of inputs are more easily separable in a higher dimensional representation. However, recent physiological data indicate that cerebellar activity is not sparse in the way anticipated by codon theory. Moreover, there is a conceptual gap between static pattern separation and the critical role of the cerebellum in dynamic tasks such as motor learning. We use mathematical analysis and simulations of cerebellar learning to identify specific difficulties inherent to online learning of dynamic tasks. We find that size expansions directly mitigate these difficulties, and that this benefit is maximised when granule cell activity is dense.

neuroscience↗

bioRxiv2022

A pals-25 gain-of-function allele triggers systemic resistance against natural pathogens of C. elegans

Regulation of immunity throughout an organism is critical for host defense. Previous studies in the nematode Caenorhabditis elegans have described an "ON/OFF" immune switch comprised of the antagonistic paralogs PALS-25 and PALS-22, which regulate resistance against intestinal and epidermal pathogens. Here, we identify and characterize a PALS-25 gain-of-function mutant protein with a premature stop (Q293*), which we find is freed from physical repression by its negative regulator, the PALS-22 protein. PALS-25(Q293*) activates two related gene expression programs, the Oomycete Recognition Response (ORR) against natural pathogens of the epidermis, and the Intracellular Pathogen Response (IPR) against natural intracellular pathogens of the intestine. A subset of ORR/IPR genes is upregulated in pals-25(Q293*) mutants, and they are resistant to oomycete infection in the epidermis, and microsporidia and virus infection in the intestine, but without compromising growth. Surprisingly, we find that activation of PALS-25 seems to primarily stimulate the downstream bZIP transcription factor ZIP-1 in the epidermis, which leads to upregulation of gene expression in both the epidermis and in the intestine. Interestingly, we find that this epidermal-to-intestinal signaling promotes resistance to the N. parisii intestinal pathogen, demonstrating cross-tissue protective immune induction from one epithelial tissue to another in C. elegans. Author summaryMulticellular organisms need to monitor the health and function of multiple tissues simultaneously to respond appropriately to pathogen infection. Here, we study an ON/OFF switch in the roundworm C. elegans that controls immune responses to diverse natural pathogens of the skin and gut. We show a physical association between the ON switch protein PALS-25 and the OFF switch protein PALS-22, and that this association is disrupted in a mutant, activated form of PALS-25. When either PALS-22 is lost, or PALS-25 is activated, a downstream immune regulator ZIP-1 is activated specifically in the skin but not the gut. Excitingly, our findings show that skin-specific loss of PALS-22 or skin-specific activation of PALS-25 can induce immune responses in the worm gut. These findings highlight the coordination of immune responses across different tissues that are commonly infected by microbial pathogens.

immunology↗

bioRxiv2022

Effect of Organic and Chemical Fertilizers on the Nutritional Composition of Amaranthus spinosus

Organic and chemical fertilizers are used in agriculture as they improve the fertility of soil and the growth of plants. So, the present investigation was designed to determine the effect of different fertilizers on the nutritional value of Amaranthus spinosus plant. The quantity of different fertilizers was used as 500 kg h-1. Some selected parameters of soil such as temperature (29.50 C), moisture (3.5 %), Water holding capacity (74%), pH (8.17), organic carbon % (1.90) and organic matter % (3.28) were measured and analysed. There was no significant variation in these parameters under different fertilizers treatment. The phytochemicals of Organic fertilizers treated plant sample had higher concentration of Alkaloid (1.06), flavonoid (0.89), tannin (1.48) and saponin (1.67), ash (7.75), moisture (87.6) and protein (9.1), Fe (0.054), Zn (0.008), Cu (0.001), Na (0.0080), Ca (113) and Mg (93) when compared to the other fertilizer treatments. Inorganic fertilizer did not show any significant effect on plant growth, while the combination of organic and chemical fertilizers was found to have a significant effect. The results reveal that organic fertilizers or their combination with chemical fertilizer are better for the crops than chemical fertilizers.

biochemistry↗