Molecular cloning, characterization, expression pattern and cellular distribution of an ovarian lipophorin receptor in the cockroach, Leucophaea maderae

Abstract

A cDNA that encodes a lipophorin receptor (LpR) with a predicted structure similar to that of the low density lipoprotein receptor (LDLR) gene superfamily was cloned from ovaries of the cockroach, Leucophaea maderae (Lem) and characterized. This is the first LpR sequenced from the order Dictyoptera. The cDNA has a length of 3362 bp coding for an 888-residue mature protein with a predicted molecular mass of ~99.14 kDa and a p I value of 4.68. The deduced amino acid sequence showed that the LemLpR harbours eight ligandbinding repeats (LBRs) at the N-terminus similar to the other insect LpRs, and thus resembles vertebrate VLDLRs. In addition to eight tandemly arranged LBRs, the five-domain receptor contains an O -linked sugar region and the classic LDLR internalization signal, FDNPVY. Northern blot analysis revealed the presence of ~4.0 kb ovarian mRNA that was transcribed throughout oogenesis with its peak especially during late previtellogenic and vitellogenic periods (from days 3 to 11). LpR transcript(s) or homologues of LDLRs were also detected in the head, midgut, Malpighian tubules, muscles and in the fat body. RNA in situ hybridization and immunocytochemistry localized the LpR mRNA and protein to germ line-derived cells, the oocytes, and revealed that LpR gene transcription and translation starts very early during oocyte differentiation in the germarium. LpR protein was evenly distributed throughout the cytoplasm during previtellogenic periods of oogenesis. However, during vitellogenic stages, the receptor was accumulated mainly in the cortex of the oocyte. Immunoblot analysis probed an ovarian LpR protein of ~115 and 97 kDa under reducing and nonreducing conditions, respectively. The protein signal appeared on day 2, increased every day and was high during vitellogenic periods from day 4 to day 7. Southern blot analysis suggested the presence of a single copy of the LpR gene in the genome of Le. maderae .

Transcriptome analysis of the almond moth, Cadra cautella, female abdominal tissues and identification of reproduction control genes

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Effect of Insulin Receptor on Juvenile Hormone Signal and Fecundity in Spodoptera litura (F.)

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Molecular characterization of the lipophorin receptor in the crustacean ectoparasite Lepeophtheirus salmonis

“…In insects, lipids are transported by the Lp from the fat body to oocytes through receptor mediated endocytosis [ 18 , 33 ]. Generally, the expression of LpR transcripts was observed throughout the ovarian development and increased during vitellogenesis of several insect species including A .…”