Caste-specific gene expression in the stingless bee Melipona quadrifasciata ? Are there common patterns in highly eusocial bees?

Abstract

Caste polyphenism is a multifaceted phenomenon, most evident in the marked differences in reproductive capacity and longevity between queens and workers. The mechanisms underlying caste differentiation and division of labor are mainly addressed in the honey bee, and recently have been studied at the molecular level. Yet, generalizations drawn from studies on this model organism require validation by comparative studies. We choose Melipona quadrifasciata, a sister-group species to honey bees, to investigate differences in gene expression between newly emerged adult queens and workers. RNA extracts were subjected to a differential display protocol (DDRT-PCR). The putative differentially expressed genes, for which annotation was available, were validated by RT-PCR and hybridization. Differential expression was observed for myosin, projectin, kettin, cytochrome P450, Rab11 and Sas10. Except for kettin, all of these were overexpressed in the worker caste. Projectin and kettin could play roles in caste-specific flight muscle organization. The putative Rab11 and Sas10 homolog genes could be involved in fertility-related cell signaling and in longevity-related gene silencing, respectively. Cytochrome P450 overexpression in Melipona workers corroborates similar findings in the honey bee, thus indicating a common function in the social insect caste syndrome.

Gene expression profiles underlying alternative caste phenotypes in a highly eusocial bee, Melipona quadrifasciata

“…With respect to ESTs representing conserved sequences, the majority of the putative genes listed in Table 3 shows high similarity to sequences from honey bee workers, and the expression of some of these have already been reported for A. mellifera . For example, the transcripts previously identified in newly emerged Melipona workers as homologs of the Sin3A transcriptional regulator (Judice et al ., 2004), diacylglycerol kinase, RNA binding protein and Na + / K + ‐ATPase, have been described as overexpressed in foraging workers of A. mellifera (Tsuchimoto et al ., 2004). Genes such as dunce and one encoding a protein kinase C (PKC)‐like kinase were shown to be expressed in adult honey bee workers (Whitfield et al ., 2002), and their counterparts are involved in behavioural traits of Drosophila (Davis & Dauwalder, 1991; Tinette et al ., 2004).…”

“…In addition, we isolated two putative receptors that could also be related to nervous system functions: a guanylyl cyclase, which is the main receptor for nitric oxide in vertebrates and invertebrates (Bicker, 2001; Ott et al ., 2004), and a scavenger receptor, which interacts with a peptide binding domain named PDZ (Ikemoto et al ., 2000). Interestingly, two PDZ domain‐containing proteins were found in libraries generated as caste‐specific transcripts of M. quadrifasciata workers, one of them in the present work and the other one reported in a previous study (Judice et al ., 2004).…”

“…To investigate the molecular mechanisms underlying caste development in Melipona , we recently undertook a comparative study on caste‐biased gene expression in Melipona quadrifasciata by a differential display RT‐PCR approach. Most of the differentially expressed genes that were annotated with respect to function turned out to be overexpressed in the worker caste (Judice et al ., 2004). The overexpression observed for the putative Rab10, Sin3A and cytochrome P450 homologs in Melipona workers is paralleled by their similar pattern of overexpression in honey bee foragers (Whitfield et al ., 2003; Tsuchimoto et al ., 2004), suggesting common patterns of caste‐specific gene expression in highly eusocial bees.…”

Physiological and genetic mechanisms underlying caste development, reproduction and division of labor in stingless bees

“…The first one was a Differential Display Reverse Transcription (DDRT) PCR strategy (Judice et al, 2004) which permitted cloning and sequencing of 14 Expressed Sequence Tags (ESTs). These represent 12 genes that are overexpressed in newly emerged workers and two genes overexpressed in queens.…”

Transcript levels of ten caste-related genes in adult diploid males of Melipona quadrifasciata (Hymenoptera, Apidae): a comparison with haploid males, queens and workers

“…In the present study we investigated transcript levels of ten genes previously identified as differentially expressed in the female castes of the stingless bee Melipona quadrifasciata (Judice et al , 2004, 2006), comparing their relative expression levels in diploid males to that of haploid ones, as well as to queens and workers. Real time RT-PCR assays were run on two time points in the adult life cycle, viz.…”