Effects Of Nikethamide Exposure On Caenorhabditis Elegans

Caenorhabditis elegans is one of nematode species and is one of free living worms under the earth rather than is parasitic in host worms or plants. The genome project was effectively completed in 1998, making C.elegans the fist multicellular organism for which the genome has been sequenced. The genome sequence data have emphasized the considerable conservation of biological mechanisms across the animal kingdom that has become apparent through the molecular genetic characterization of biological processes. The worm was introduced as a model organism by Sydney Brenner and soon became a favorable laboratory organism due to a number of advantages such as the worms have short life cycle and are transparent throughout their entire life; they are small enough (the adult worms are approximately 1mm long) to be grown in large quantities under standardized conditions on either Petri dishes or in liquid culture(e.g. 96-well plates), and cellular and organ development can be observed through the microscope(for detailed overview, see Kenyon 1988) and its sensitivity to different kinds of stresses. C.elegans is frequently used in studies to test the effects of various drugs and chemicals on development and life span. For instance, it is reported that certain anticonvulsant drugs like Ethosuximide,certain antidepressant drugs like Manserin can prolong the life span of C.elegans while in the other hand that copper,chromium and arsenic are toxic to C.elegans,and ethanol and ginsenosides can affect C.elegans lifespan too.In our study, we established the micro-liquid culture method. The optimal conditions of the micro-liquid culture method: the concentration of bacteria was 6mg/ml; the effective concentration of FUDR to prevent self-fertilization was 0.12mM; 10-15 worms per well was proper. We investigate the effects of Nikethamide exposure on Caenorhabditis elegans. In this study, worms were cultured in micro-liquid 96-well plates which contain varied concentrations of Nikethamide, the results show that Nikethamide significantly shorten life expectancy. The low concentration 19mM group decreased the lifespan by 34%, the middle concentration group 28mM group decreased the lifespan by 47%,and the high concentration 47mM group decreased the lifespan by 60%. Nikethamide shortened the lifespan of C.elegans, and the higher the dose, the shorter the lifespan was. Modulation of insulin/ IGF signaling in the C.elegans is the central determinant of the endocrine control of stress response, diapause, and aging. The emerging picture is that insulin-like molecules, through the activity of the DAF-2/insulin/IGF-1-like receptor, control the ability of the organism to deal with oxidative stress, and interfere with metabolic programs that help to determine lifespan. Therefore, the shortened lifespan effect in this experiment may result from it too. However, the insulin-like signaling pathway is not known very clear yet, further research evidences need to be found.Nikethamide delayed the development and maturity of L1 C.elegans, resulted in a shortened body-length due to worms not fully developed.Nikethamide blocked the egg-laying activity of C.elegans evidenced as delayed the onset of egg-laying period, reduced the average number of eggs, and increased the incidence of wormbag phenomenon (could be observed in control group occasionally). The reason for the egg-laying activity being blocked may be that Nikethamide delayed the development of L1 C.elegans, thereby caused the worms not fully matured and resulted in low average number of eggs. The other reason maybe that Nikethamide affected vulva muscles development of C.elegans, thus the worms couldn't lay the eggs out, which is also the reason for the increase of wormbag phenomenon ratio. The third reason could be that worms exposed in Nikethamide had detected that the external environment was harmful for its breeding and if they pop its offspring out into the external environment, its progeny larvae's development would be inhibited as a result. So the parent worms kept the eggs inside its body, and thereby avoid the adverse environment. Using micro-liquid culture method in assessing the effects of Nikethamide exposure on C.elegans proved the method is practical and has comprehensive application, as evidenced by many obvious advantages such as simple, fast, accurate, and economic etc. Since C.elegans evolutionarily shared common conserved signaling pathways and molecular regulatory mechanisms with humans, therefore, this experiment laid a foundation for further study of related molecular mechanisms as well as the impact of Nikethamide on humans and animals.