Identification Of The Novel Genes Involved In Pathogenic Learning Of C.Elegans

Caenorhabditis elegans has short life cycle,simple structure,and a transparent whole body.These advantages make it become an ideal model to study biology.In particular,nematodes that feed on soil bacteria need to face of temptation of all kinds of nature food.To distinguish food bacteria from the pathogenic bacteria,nematodes need efficacy sense systems and acquired learning ability to recognize the threat of adverse bacteria.Nematodes have two types of learning that is associative learning and non-associative learning.Pathogenic avoidance learning belongs to the associative learning that help nematodes quickly recognition adverse stimulation of the relationship between smell and food,which regulates their own behavior and improves the efficiency of foraging.Therefore,this learning behavior has the vital role for the survival for C.elegans.As a neurobiological behavior,there are a few reports of pathogenic avoidance learning,and those investifations can not fully explain all of mechanisms related to associated learning.In order to identifythe potential genes involved in the associated learning,we used the high-through data from the study of mice or humans,and further employed the model biology of C.elegans to find out the novel genes that have effects on the pathogen avoidance learning as well as it molecular mechanisms.This investigation is also helpful to understand the complex neurobiological process,such as the associated learning in higher mammal.In our current study,the main results are as follows:1.Determine a new genes ZK337.1 participating in avoidance learning of the pathogenic bacteria PA14Based on memory and forgotten plastic related genes,through the method of RNAi screening,it was found that the knock-down of gene ZK337.1 in C.elegans led to the defects inpathogen avoidance learning caused by Pseudomonas aeruginosa PA14.Next,the behavior assay to ZK337.1 mutant was also defective in learning.Furthermore,the complementary expression of ZK337.1 rescued the learning defect.At the same time,ZK337.1 mutant animal showed the normal olfactory chemotaxis and the nomal locomotion.Therefore,our results suggested that ZK337.1 should be involved in regulation of pathogen aversive learning.2.The identification of the molecular pathways of ZK337.1.We tried to identify the genes mayfunction upstream or downstream of ZK337.1.Our result showed that the upstream Toll-like signaling pathway key genes ikb-I,pik-I,tol-I and STAT the transcriptional factors in STAT family sta-2,sta-1,as well as the downstream key genes daf-7,daf-1 in the daf-7-daf-1/TGF-? signaling pathways had no effects on the pathogen aversive learning.The result also implied that gene ZK337.1 in the pathogen avoidance learning may be independent of the signaling pathways above.3.sid-3 is the other novel genes involved in pathogen avoidance learning.We also screened the other new gene sid-3 affecting pathogen avoidance learning of C.elegans.Meanwhile we tested the gene cdc-42 that had been reported to interact with SID-3 via CRIB domain,but our result showed that cdc-42 does not participate in this process,suggesting that sid-3 regulate the avoidance learning independent on CDC-42.Moreover,Psid-3::mCherrywas constructed to map its expression in vivo,and the localization of two pairs of tail neurons,including PHAL,PHAR,PHBL,and PHBR whose function were associated with the release of neurotransmitter serotonin,was monitored.Therefore,we speculated that the expression in these two pairs of chemotaxis neurons might be responsible for the pathogen avoidance learning,though more experimental evidences should be required.Additionally,detection ZK337.1 mRNA expression level in the sid-3 mutant animal also revealed the significantly increase of ZK337.1 mRNA.But the interrelation between those two genes in the pathogen avoidance learning remained unclear.Innovation of my current investigation includes as follows:Those two novel genes ZK337.1 and sid-3 are firstly suggested to be involved in the pathogen avoidance learning of C.elegans.