Salmonella Typhimurium fepB negatively regulates C. elegans behavioral plasticity.

OBJECTIVES: Dauer is an alternative developmental stage of Caenorhabditis elegans (C. elegans) that gives survival benefits under unfavorable environmental conditions. Our study aims to decipher C. elegans dauer larvae development upon Salmonella Typhimurium infection and how the bacterial gene regulating the worm's behavioural plasticity for better survival. METHODS: Age-synchronized L4 C. elegans worms were infected with Salmonella Typhimurium 14028s (WT-STM) strain and mutant strains to check the dauer larvae development using 1% SDS. Besides, bacterial load in animals' gut, pharyngeal pumping rate and viability were checked. Worm's immune genes (e.g., ilys-3, lys-7, pmk-1, abf-2, clec-60) and dauer regulatory genes (e.g., daf-7, daf-11, daf-12, daf-16, daf-3) were checked by performing qRT-PCR under infection conditions. RESULTS: We found that deletion of the fepB gene in S. Typhimurium strain became less pathogenic with reduced flagellar motility and biofilm-forming ability. Besides, there was decreased bacterial burden in the worm's gut with no damage to their pharynx. The fepB mutant strain was also able to enhance the immune responses for better survival of worms. Infection with mutant strain could activate dauer signaling via the TGF-ß pathway leading to a significant increase in dauer formation than WT-STM infection. CONCLUSION: Our study indicated that the bacteria act as a food source for the growth of C. elegans and development and can act as a signal that might be playing an essential role in regulating the host physiology for their survival. Such a study can help us in understanding the complex host-pathogen interaction benefiting pathogen in host dissemination.

Nanoparticles as a potential teratogen: a lesson learnt from fruit fly.

ABSTARCT Nanoparticles (NPs) have revolutionized the society being a part of numerous products of day to day uses. However, its potential to act as an adverse entity was greatly ignored. Recently, the toxic effect of nanoparticles on biological system is checked using various model organisms. Among various models fruit fly Drosophila melanogaster has turned up as a promising model since numerous diseased genes and signalling pathways are similar to that of a human being. Effects of many NPs were tested using Drosophila, and results suggest the deleterious effect of NPs on the various physiological system. NPs cause defects in genetic, molecular, phenotypic, developmental as well as behavioral level in Drosophila. Any chemical compounds that can cause abnormalities in offspring when ingested in prenatal stages are known as teratogens. In this review, we have summerized the toxic effect generated by NPs tested using Drosophila model and propose NPs as a teratogen.

Behavioral Teratogenesis in Drosophila melanogaster.

Developmental biology is a fascinating branch of science which helps us to understand the mechanism of development, thus the findings are used in various therapeutic approach. Drosophila melanogaster served as a model to find the key molecules that initiate and regulate the mechanism of development. Various genes, transcription factors, and signaling pathways helping in development are identified in Drosophila. Many toxic compounds, which can affect the development, are also recognized using Drosophila model. These compounds, which can affect the development, are named as a teratogen. Many teratogens identified using Drosophila may also act as a teratogen for a human being since 75% of conservation exist between the disease genes present in Drosophila and human. There are certain teratogens, which do not cause developmental defect if exposed during pregnancy, however; behavioral defect appears in later part of development. Such compounds are named as a behavioral teratogen. Thus, it is worthy to identify the potential behavioral teratogen using Drosophila model. Drosophila behavior is well studied in various developmental stages. This chapter describes various methods which can be employed to test behavioral teratogenesis in Drosophila.