Gene expression profiles among immature and adult reproductive castes of the termite Reticulitermes flavipes

Abstract

Array-based genomic studies were conducted with the goal of identifying immature (i.e. nymph) and adult reproductive caste-biased gene expression in the termite Reticulitermes flavipes. Using cDNA macro-arrays, we identified thirty-four nymph-biased genes falling into eight ontogenic categories. Based on gene expression profiles among diverse castes and developmental stages (determined by quantitative PCR), several important trends emerged. These findings highlight the importance of several developmental and survival-based factors among immature and adult termite reproductives, including: vitellogenesis, nutrient storage, juvenile hormone sequestration, ribosomal translational and filtering mechanisms, fatty acid biosynthesis, apoptosis inhibition, and both endogenous and symbiont cellulase-assisted nutrition. These findings are highly significant as they are the first to elucidate the molecular biology underlying termite reproductive caste differentiation and reproductive caste-specific biology. Other gene expression results are in agreement with previous findings that suggest roles for vitellogenin-like haemolymph proteins in soldier caste differentiation.

Molecular traces of alternative social organization in a termite genome

“…19). One of these duplications is closely related to Neofem3, a reproductive-specific gene in three other termite species (Cryptotermes secundus, C. cynocephalus and Reticulitermes flavipes) [35][36][37][38] . Three of the four Vg genes, including the recent duplications, were significantly overexpressed in reproducing queens (Fig.…”

Regulation of polyphenic caste differentiation in the termiteReticulitermes flavipesby interaction of intrinsic and extrinsic factors

“…Prior to knowing their identity, hemolymph-soluble hexamerin protein forms were found to increase in abundance during JH-induced soldier caste differentiation (Scharf et al, 2005a). From nymph and presoldier array screens, expressed sequence tags representing the two hexamerins were identified and, subsequently, fulllength cDNA sequences were obtained (Scharf et al, 2005b;Zhou et al, 2006b). The protein sequences deduced from the full-length cDNAs revealed that the Hex-1 protein has a unique hydrophobic tail with a putative JH-binding prenylation site and that the Hex-2 protein has a unique hydrophilic insertion with unknown function.…”

Social exploitation of hexamerin: RNAi reveals a major caste-regulatory factor in termites

“…Several tools and resources have become available in recent years to study the molecular basis of termite caste differentiation (5,6,10,11,18). Using these tools, we previously identified two JH-responsive and morphogenesis-associated hexamerin genes that are referred to as Hex-1 and Hex-2 (6,11).…”

“…Termite caste differentiation is a postembryonic developmental process that is the result of differential gene expression (4)(5)(6)(7). Lower termites such as the Reticulitermes undergo a caste differentiation process that is truly unique among the social insects (see Fig.…”

“…Using these tools, we previously identified two JH-responsive and morphogenesis-associated hexamerin genes that are referred to as Hex-1 and Hex-2 (6,11). Because hexamerins have well defined roles as JH-binding proteins (19,20), because of the well established role of JH in termite caste differentiation (15), and on the basis of our observations that one of the hexamerins (Hex-2) is highly induced in response to rising JH titers during presoldier differentiation (11), we sought to further functionally characterize the Reticulitermes flavipes hexamerins.…”