| Insect immunity has received a great deal of attention in the past 20 years both from a basic research as well as applied perspective. However, the most of studies had been facused on the immune response to bacteria and the antibacterial defence reactions have been investigated in insects. The immune response to fungus is poorly understood and the studies are few at molecular level. So infection caused by fungi became the object of recent interest.Metarhizium anisopliae, a kind of entomopathogenic fungus widely applied in domestic and abroad, has an important role in biological control of insect, The migrat- ory locust (Locusta migratoria) is an orthopteran pest and a reprensentative member of hemimetabolous insects, in the course of long evolution, it adopt own immune system with great significance for biological studies. Its transcriptomic data on infection by fungi would provide invaluable information for molecular entomology and pave a way for the comparative research of other medically, agromically, and ecologically relevant insect. A better understanding of fungal-induced immune responses would identify the insect defense genes, and hence help establish new strategies to accelerate host death in a biological control scenario to fight against important pests.In this paper, a method was developed for construction normalized cDNA library by using mRNA extracted from the fat body and hemocyte of locust 12-36 h after injection of spores of M. anisopliae. The extracted mRNA was checked free of fungal DNA/ mRNA by RT-PCR and PCR, and then used for constructing cDNA library with SMART (Switching Mechanism At 5' end of RNA Transcript Method) after normalization by DSN (Double Specific Nuclease). 200 clones were randomly picked from the library and sequenced, resulted in 190 ESTs. Analysis of the 190 ESTs revealed 165 unigenes and no fungal genes, the 165 unigenes were related to metabolism, immune-related factor, receptor, peptidase, cytoskeleton, ribosomal, mitochondrial and transcriptional control. These results suggest that this method is reliable and feasible for constructing host cDNA library from mycosed insect.The main results were as follows:1. The sensitivity of locust specific primer H1, H2 and M. anisopliae specific-primer Tu1, Tu2 were desiged according to locust histone gene and M. anisopliae tubulin gene and analyzed by PCR for their specificity and sensitivity. The results showed that 1pg locust DNA can be detected by using locust specific-primer H1, H2 and 10 pg of M.anisopliae can be detected by using M.anisopliae specific-primer Tu1, Tu2.2. Haemocytes and fat body of host infected by M. anisopliae were chosen as materials for extracting mRNA, no fungus DNA and RNA were found by RT-PCR and PCR with the two special pairs of primer in the mRNA extracted.3. To date, for the first time, a normalized cDNA library was constructed from fat body and hemocyte of the host insect infected by entomopathogenic fungus. 200 randomly selected cDNA clones from cDNA library were sequenced and analyzed against Genebank using Blast-X and Blast-N. It is found that approximately 57% cDNA sequences did not exhibit significant homology (Evalue>10-5) to genes in the Genebank database, while 43% had highly confident matches (Evalue<10-5). No sequences were found to have significant similarity with fungus genes after comparison with the data of Genebank.
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