Molecular cloning and analysis of four cDNAs from the heads of Apis cerana cerana nurse honeybees coding for major royal jelly proteins

A cDNA library was constructed from 8-day-old worker heads of Apis cerana cerana. A DIG-labeled probe derived from part of an Apis cerana mrjp3 genomic segment was used to screen the library. One hundred and twenty positive clones were identified and characterized. Thirty one clones were homologous with major royal jelly proteins (MRJPs) of Apis mellifera. The most abundant MRJP homologue was MRJP1 ( 11 clones), followed by MRJP3 ( 10 clones), MRJP2 ( 7 clones) and MRJP5 ( 3 clones). Clones containing A. cerana cerana MRJP1, MRJP2, MRJP3 and MRJP5 cDNAs were identified, completely sequenced, and analyzed with bioinformatics software. Several lines of evidence suggested that the identified cDNAs code for major royal jelly proteins of A. cerana. In addition to polymorphic regions of MRJP3 and MRJP5, another polymorphic repetitive region was found in AccMRJP2. The polymorphism of AcMRJP2 and AcMRJP5 repeat regions were tested by PCR with genomic DNAs of individual honeybees. Different properties of the repetitive regions of MRJP2 genes in two closely related Apis species were discussed.