Identification And Function Of Sterol Carrier Protein-2 Gene From Heliocoverpa Armigera

The sterol carrier protein-2 is an lipid carrier which is widely found in both vertebrates and invertebrates, it is tightly connected with intracellular cholesterol trafficking and lipid transport. In the area of SCP-2, previous studies are focused on invertebrates, little reports can be found in SCP-2 of invertebrates. Intracellular cholesterol trafficking is thought as critical process in insects. SCP-2 is the main carrier protein involved in cholesterol transport of insects.Cotton bollworm is a major agriculture pest in irrigated crops and occurs widely in most countries in the world. We use RT-PCR to detect SPC-2 transcripts in different tissues of Cotton bollworm larvae,and also in different larvae stage including eggs. SCP-2 is detected in all the tissues in different larvae stage, especially in the midgut and fatbody of 4th and 5th larvae, high level of SCP-2 is Detected.While in the other part of larvae,as head, EP(epidermis), hindgut, Mt(malpighian tube), the level of SCP-2 is very low.The expression of SCP-2 also is not very high in both pupae and moth. Useing the technique of western blot, polyclonal antibodies against the Aedes aegypti sterol carrier protein-2 (AeSCP-2) detect a protein of 17KD in most tissues of 4th and 5th larvae.Therefore,SCP-2 might be important for Helicoverpa. armigera, it may be take part in intracellular cholesterol trafficking and transport.We extract RNAs from dissected fat body and midgut tissues of 4th larvae, islate and identify the SCP-2 gene in Helicoverpa. armigera via RT-PCR method and get 442bp gene fragment.The 3'part of SCP-2 cDNA is also obtained by RACE technique,about 649bp.In this study AeSCPIs,including both AeSCPI-1 and AeSCPI-2,which are potentially toxic to the yellow fever mosquito, are used in biological assays of Cotton bollworm larvae by different concentrations,from10mM to 0.01mM. The results indicate that when then concentration is very low (0.01mM), the larvaes are not influced,when the concentration is 1mM, those AeSCPIs also have slightly influence in larvae, mainly result in the loss of body weight. Regarding the SCP-2 gene,more researches can be done in the future,the whole HaSCP-2 cDNA would be got, the potential fucntion of HaSCP-2 genes will be investigated, the location of SCP-2 both in cells and larvae can be detected, the inhibitor of HaSCP-2 will be screened. As a new biological target, Ha SCP-2 have a far-reaching significance on the research of integrated insectcides.