| Polyrhachis vicina Roger as eusocial insects belongs to the genus Polyrhachis (Hymenoptera;Formicidae),which is an important resource insect. This species has the different castes, highly complex nervous system and social behavior. P. vicina is a good material which is used for study the insect development, behavior and neurological function.Semaphorin 2a (sema) belong to the second sub-group of Semaphorin family which is a a secreted protein exists in invertebrates. This gene as a neural inhibitory factor plays an important role in the neural connections and axon guidance in the central nervous system.Cathepsin-D is a aspartic endopeptidase,which is produced by estrogen in the acidic pH. Cathepsin-D is related with tumor development in mammals, which has been regarded as indicators of tumor aggressiveness. In insects, Cathepsin-D as a proteolytic enzyme is involved in the biological process of embryonic development, especially posesses a very important functionin in the metamorphosis of insect.In this paper, the mRNA expression of Semaphorin 2a were investigated by in situ hybridization in the untrained ant and the trained worker of P. vicina; Cathepsin-D full-length cDNA sequence was cloned through the ways of RT-PCR and 5'and 3'RACE technology, and the analysis and forcast of the nucleotide sequence and protein Sequences were completed by used the bioinformatics methods. These results are as follows:l.The localization expression.of Semaphorin 2a mRNA is studied in the head of different castes by in situ hybridization. The results show that Semaphorin 2a are widely expressed in the brain of P. vicina, indicating that this gene is involved in the learning and memory, olfactory, visual and behavior. This gene as a neural inhibitory factor play an important role on the nervous system of insects.The expression have different level in different castes,so we suggested that the difference expression of semaphorin 2a in the same brain region of different castes was contacted with the behavior and duties of the three castes.2.The expression of Semaphorin 2a was investigated by in situ hybridization in the trained workers of Polyrhachis vicina which were trained by Y-maze. The results show that the expression of Semaphorin 2a in the trained ants was significantly reduced. We analyzed the number and structure of synaptic had changed when the workers was trained and the inhibition of synaptic was weaken, so the expression in the workers' head was reduced.3.The Cathepsin-D full-length of P. vicina was obtained by RT-PCR and RACE techniques.The full-length is 1655bp,and the longest reading frame is 1155bp, encoding 384 amino acids,also,5'untranslated region (5'-UTR) is 153bp and 3'untranslated region (3'-UTR) is 341bp.The corresponding protein containing a signal peptide is a secreted protein with a predicted molecular mass of 41.6kDa and with the theoretical pI of 6.25.The analysis of homology showed that the full length cDNA of Cathepsin-D has similarity of Apis 87%, Apriona 73%, castaneum 72% and Drosophila 69%, all were more than 30%. Consequently, the sequence of this gene named Pv-cath-D indeed encodes the ant CTSD protein, submitted to GenBank and assigned the accession number JF759824.We have investigated the mRNA expression of level of Semaphorin 2a by in situ hybridization in different castes and the trained worker of P. vicina for the first time, and cloned the full-length cDNA of Cathepsin-D from P. vicina, also analysed the nucleotide sequence and protein sequences through the bioinformatics methods. These results will provide the basis for further research of Semaphorin 2a and Cathepsin-D in insects. |
