The Effect Of Heavy Metal Cadmium Stress On The Growth, Development And Defense Ability Of Drosophila Melanogaster

Cadmium(Cd)is one of the common heavy metal pollutants,which can cause different degrees of damage to organisms.Cd is not an essential element for biological growth,but it can be passively absorbed by animals and plants and stored in the body.It enters the human body through the food chain,endangering human health.Studies have shown that cadmium may exert its toxic effects by inducing ROS,oxidative damage,or epigenetic changes,which are widely manifested in the life span,reproduction,growth and development of organisms.At the same time,the body will also launch a series of defense mechanisms to cope with heavy metal stress and other adverse external stimuli,is related to detoxification enzyme activity changes and immune defense related gene expression changes.Drosophila melanogasler is one of the most common model organisms.The whole genome sequence analysis shows that Drosophila melanogaster has high homology with human genome and plays an irreplaceable role in developmental genetics,toxicology and other research fields.21 this study,the Canton-S strain of Drosophila melanogaster was used as experimental material.The eggs were treated with different concentrations of cadmium(0 mg/kg,1 mg/kg,2 mg/kg,4 mg/kg and 8 ng/kg).When the eggs develop into larvas,the body weight and body length of the larvae were measured.The pupation and eclosion time,as well as the number of pupae and eelosion per day in a certain number of days were counted.The effects of cadmiul on the development time and development activity of Drosophila zelanogaster.The changes of glutathione S-transferse(GST)and carboxylesterase(CarE)activities in larvae,larvae,1 d,5 d and 10 d adults were detected to explore the effects of cadrnium stress on related detoxification enzymes.On this basis,the expression levels of growth and development related genes(baz,?-Tub60D and tj)and defensc resistance related genes(cdc42,?-Tub84B and dx)were further detected to explore the differences.The effects of cadmium concentration on the growth,development and defense resistance of Drosophila larvae and adults and the related mechanisls.The results arc as follows:(1)The length of larvae decreased with the increase of cadnium concentration.Compared with the control group,the length ot larvae decreased signitlcanliy(P<0.05),at the concentrations of 4 mg/kg and 8 mg/kg,while the weight increased first and then decreased.Compared with the control group,the weight of larvae increased significantly at the concentrations of 1 mg/kg and 2 mg/kg(P<0.05).The pupation time was significantly prolonged(P<0.05).The peak pupation time and peak pupation time of cadmium treated group were also significantly lower than those of control group during 5 consecutive days of pupation recording.The emergence time and emergence activity showed similar trends.After reaching adults,the body weight of adult flies was measured.The results showed that the body weight of female and male adults increased significantly in the medium concentration treatment group,but the body weight of male adult flies decreased by 10 days.The results showed that cadmium stress could affect the growth and development of Drosophila melanogaster,delay the development time and reduce the development activity.(2)Compared with the control group,the activity of GST in larvae and adult flies decreased at different concentrations of cadmium(P<0.05),but there was no cadmium concentration dependence;the activity of CarE in larvae and adult flies showed an inverted "V" pattern,which was different from that of GST.(3)The expression of-growth-related genes and resistance-related genes in larvae and adult flies of 1 d,5 d and 10 d.The results showed that the expression of growth-related genes baz and ?-Tub60D increased significantly after cadmium treatment,while the expression of tj decreased significantly after cadmium treatment.The expression of defense-related genes cdc42 and ?-Tub84B decreased significantly after cadmium stress.There was a significant increase in dx,but a significant decrease in dx in larvae and adult flies under cadmium stress.These gene expression changes may be related to the multiple regulation of phagocytosis and Notch signaling pathways.In this study,Drosophila melcmogaster was taken as the research object.The effects of cadmium stress on the growth and development of larvae and adult flies of different ages,the activities of detoxification enzymes in vivo and the mechanism of defense resistance of Drosophila melanogaster were analyzed,and the possible molecular mechanism was discussed.These studies laid an experimental foundation for further exploring the toxic effect of cadliul on Drosophila melartogasler and its molecular mechanism,and provided experimental basis for the study of molecular mechanism of human diseases caused by heavy metals.