Effects Of High-sugar Diets On Body Fat,Memory And Movement Of Caenorhabditis Elegans

Long-term high-sugar diet may disrupt metabolic balance and cause metabolic diseases,the impact of which is likely a long,slow process from quantitative changes to qualitative changes.Prior to a specific disease,related phenotypic changes such as body fat content,learning and memory,and exercise capability may occur.Understanding these phenotypic changes is of great significance for exploring pathological changes of such diseases.Caenorhabditis elegans is a model organism with rich genetic resources and short life cycle,which can be easily used for lifelong and even transgenerational tracking of phenotypes.It has increasingly become a new tool for studying active food ingredients and nutrition.Using C.elegans as a model here we studied the effects of high-sugar diet on the above-mentioned phenotypic changes.The main results are as follows:1.Preference and selectivity of C.elegans to different sugars.We first tested the food perception ability of C.elegans with sour,sweet,salty and other taste substances,and found that C.elegans can perceive different tastes and have a preference for sweetness.Then through pairwise selection experiments,C.elegans was found to have no preference for glucose,fructose or sucrose but showed an avoidance behavior to trehalose.Further experiments using multiple selection assays also confirmed low selectivity of C.elegans for trehalose.2.Effects of different feeding methods and different sugars on the body fat level and body size of C.elegans.We first carried out a lifelong tracking analysis of body fat levels of the C.elegans on NGM solid medium fed with E.coli OP50,the routine laboratory bacterial food,and found that the body fat levels of the nematodes were relatively stable.Then,we found that both adding glucose into NGM agar(absorption through body surface)and mixing with bacterial food(normal feeding)could increase the body fat level of C.elegans.Further experiments under the feeding mode found that fructose,sucrose and trehalose could also increase the lipid level of C.elegans,but sucrose and trehalose had a greater degree of improvement than glucose and fructose,while trehalose also reduced the size of C.elegans to a certain extent.Next,we analyzed the effects of axenic culture conditions on the body fat and body shape,and found that axenic culture of C.elegans in Ce MM medium had lower body fat content,while being thinner and longer,as compared to C.elegans grown on NGM medium eating normal bacteria food.When the above sugars were added to Ce MM medium,on sucrose was found to increase the body fat level of C.elegans.3.Effect of high-sugar diet on the learning and memory ability of C.elegans.In the case of NGM solid culture and normal ingestion of E.coli OP50,as compared with the control,the memory ability of the C.elegans decreased faster with the aging process when glucose and trehalose were added.In the Ce MM liquid medium supplemented with glucose,fructose and trehalose,the learning and memory ability of the C.elegans decreased more slowly than the control,but that supplement with sucrose decreased faster.Taken together,these results provide a basis for further studies on high-sugar diet and its efffect on lipid metabolism and on learning and memory behaviors,and thus provide an insight into the screening of bioactive ingredients and their applications in food and pharmaceutical industries.