title: The gene road to royalty--differential expression of hydroxylating genes in the mandibular glands of the honeybee.
abstract: The advances in honeybee sociogenomics have paved the way for the study of social communication processes at the gene level, in particular the expression of caste-specific pheromones. The queen honeybee mandibular pheromone provides an excellent model system, in that biosynthesis of the hydroxylating fatty acid caste-specific pheromone appears to be reduced to a single chemical hydroxylation step of stearic acid. Queens are typified by omega-1-hydroxylation, as opposed to the worker-typical omega-hydroxylation. We hypothesized that this bifurcation is the consequence of differential expression of caste-specific genes that code for fatty acid-hydroxylating enzymes from the cytochrome P450 (CYP) family. Bioinformatics studies disclosed two candidate proteins CYP4AA1 and CYP18A1. We thus investigated the expression of these genes in the mandibular glands of queens, and of queenright (QR) and queenless (QL) workers. The real-time PCR results revealed that CYP4AA1 (omega-hydroxylation) was expressed at high levels in both QR and QL workers, whereas in queens its expression was negligible. The expression of CYP18A1 (omega-1-hydroxylation), on the other hand, was high in the queen's glands and negligible in those of QR workers. In QL workers, however, the expression of CYP18A1 was considerably elevated and significantly greater than in QR workers. Three-dimensional structural models constructed for these enzymes demonstrate differences in the active site between CYP18A1 and CYP4AA1, in line with their differential catalytic specificity. The fact that queen pheromone plasticity can be tracked all the way to gene expression provides a new insight into the process of caste differentiation and the accompanying social communication.
authors.affiliation: Department of Zoology, George S. Wise Faculty of Life Sciences, Tel Aviv University, Ramat Aviv, Israel.
authors.forename: Osnat
authors.initials: O
authors.lastname: Malka
authors.forename: Iris
authors.initials: I
authors.lastname: Karunker
authors.forename: Adva
authors.initials: A
authors.lastname: Yeheskel
authors.forename: Shai
authors.initials: S
authors.lastname: Morin
authors.forename: Abraham
authors.initials: A
authors.lastname: Hefetz
mesh_terms: D000595:Amino Acid Sequence; D000825:Animal Structures / Q000201:enzymology; D000818:Animals; D001516:Bees / Q000201:enzymology* / Q000235:genetics* / Q000502:physiology; D020134:Catalytic Domain / Q000235:genetics; D003577:Cytochrome P-450 Enzyme System / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D005260:Female; D015971:Gene Expression Regulation, Enzymologic; D017344:Genes, Insect; D007301:Insect Hormones / Q000096:biosynthesis; D008958:Models, Molecular; D008969:Molecular Sequence Data; D010675:Pheromones / Q000096:biosynthesis; D011487:Protein Conformation; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D012098:Reproduction; D017386:Sequence Homology, Amino Acid; D012919:Social Behavior
chemical_list: D007301:Insect Hormones; D010675:Pheromones; D012333:RNA, Messenger; D003577:Cytochrome P-450 Enzyme System