Isolation and characterization of a Cotesia rubecula bracovirus gene expressed in the lepidopteran Pieris rapae

Polydnaviruses are endogenous particles that are crucial for the survival of endoparasitoid wasps, providing active suppression of the immune function of the lepidopteran host in which wasp larvae develop. The Cotesia rubecula bracovirus (CrBV) is unique in that only four gene products are detected in larval host (Pieris rapae) tissues and expression of CrBV genes is transient, occurring between 4 and 12 h post-parasitization. Two of the four genes, CrV1 and CrV3, have been characterized. CrV1 is a secreted glycoprotein that has been implicated in depolymerization of the actin cytoskeleton of host haemocytes, leading to haemocyte inactivation; CrV3 is a multimeric C-type lectin that shares homology with insect immune lectins. Here, a third CrBV-specific gene is described, CrV2, which is expressed in larval P. rapae tissues. CrV2, which is transcribed in haemocytes and fat body cells, has an ORF of 963 bp that produces a glycoprotein of approximately 40 kDa. CrV2 is secreted into haemolymph and appears to be internalized by host haemocytes. CrV2 has a coiled-coil region predicted at its C-terminus, which may be involved in the formation of putative CrV2 trimers that are detected in haemolymph of parasitized host larvae.

Enhancing the ratio of molecular ions to non-covalent compounds in the electrospray interface of LC-MS in quantitative analysis

A common problem encountered during the development of MS methods for the quantitation of small organic molecules by LGMS is the formation of non-covalently bound species or adducts in the electrospray interface. Often the population of the molecular ion is insignificant compared to those of all other forms of the analyte produced in the electrospray, making it difficult to obtain the sensitivity required for accurate quantitation. We have investigated the effects of the following variables: orifice potential, nebulizer gas flow, temperature, solvent composition and the sample pH on the relative distributions of ions of the types MH+, MNa+, MNH+, and 2MNa(+), where M represents a 4 small organic molecule: BAY 11-7082 ((E)-3-[4-methylphenylsulfonyl]-2-propenenitrile). Orifice potential, solvent composition and the sample pH had the greatest influence on the relative distributions of these ions, making these parameters the most useful for optimizing methods for the quantitation of small molecules.