Identification of zebrafish magnetoreceptor and cryptochrome homologs

Magnetoreception is essential for magnetic orientation in animal migration. The molecular basis for magnetoreception has recently been elucidated in fruitfly as complexes between the magnetic receptor magnetoreceptor(Mag R) and its ligand cryptochrome(Cry). Mag R and Cry are present in the animal kingdom. However, it is unknown whether they perform a conserved role in diverse animals. Here we report the identification and expression of zebrafish Mag R and Cry homologs towards understanding their roles in lower vertebrates. A single magr gene and 7 cry genes are present in the zebrafish genome. Zebrafish has four cry1 genes(cry1aa, cry1 ab, cry1 ba and cry1bb) homologous to human CRY1 and a single ortholog of human CRY2 as well as 2 cry-like genes(cry4 and cry5). By RT-PCR, magr exhibited a high level of ubiquitous RNA expression in embryos and adult organs, whereas cry genes displayed differential embryonic and adult expression. Importantly, magr depletion did not produce apparent abnormalities in organogenesis. Taken together, magr and cry2 exist as a single copy gene, whereas cry1 exists as multiple gene duplicates in zebrafish. Our result suggests that magr may play a dispensable role in organogenesis and predicts a possibility to generate magr mutants for analyzing its role in zebrafish.

An improved hybrid bream derived from a hybrid lineage of Megalobrama amblycephala(♀)×Culter alburnus(♂)

Distant hybridization is an important technique in fish genetic breeding.In this study,based on the establishment of an allodiploid fish lineage(BT,2n=48,F_(1)–F_(6))derived from distant hybridization between female Megalobrama amblycephala(BSB,2n=48)and male Culter alburnus(TC,2n=48),and the backcross progeny(BTB,2n=48)derived by backcrossing female F_(1) of BT to male BSB,an improved hybrid bream(BTBB,2n=48)was obtained by backcrossing BTB(♀)to BSB(♂).Moreover,the morphological and genetic characteristics of BTBB individuals were investigated;BTBB was similar to BSB in appearance but had a higher body height than BSB.The study results regarding chromosome numbers and DNA content indicated that BTBB is a diploid hybrid fish.The 5S rDNA and Hox gene of BTBB were inherited from the original parents.Gonadal development in BTBB was normal.On the other hand,BTBB had a faster growth rate,higher muscle protein level,and lower muscle carbohydrate level than BSB.Hence,bisexual fertile BTBB is promoted and can be applied as a high-quality fish,and it can also be used as a new fish germplasm resource to develop high-quality fish further.Thus,this study is of great significance for fish genetic breeding.

Mapping the transcription repressive domain in the highly conserved human gene hnulp1

HNULP1,a new member of the basic helixloop-helix transcription factors,contains a DUF654 domain in its C-terminus and is highly conserved from Drosophilae,yeast,zebrafish to mouse.The function of this motif,however,is currently unknown.In this research,we fused five deletion fragments of the DUF654 domain to the GAL4 DNA-binding domain and then co-transfected with plasmids L8G5-Luc and VP-16.The analysis of the GAL4 luciferase reporter gene indicated that fragments from 228 to 407 amino acids in the DUF654 domain had a strong transcription repression activity.Therefore,this study lays a solid foundation for research on the mechanism of hnulp1 transcriptional regulation and the function of the DUF654 domain.