Ecdysteroid-dependent protein synthesis in caste-specific development of the larval honey bee ovary

Abstract

In the honey bee, Apis mellifera, the fifth larval instar is a critical period for caste differentiation. During this premetamorphic phase the hormonal milieu shows pronounced caste differences and several organs, particularly the ovaries, enter different developmental pathways leading to highly fertile queens and nearly sterile workers. Developmental profiles of total protein synthesis in larval ovaries showed marked caste differences starting with the early fifth instar. By two-dimensional electrophoresis, caste-specific patterns could be detected in the synthesis of a 29 kDa/pI 4.6 and two 24 kDa/pI 5.2-5.5. proteins (pI=isoelectric point). A marked decrease in the expression of these proteins was found to coincide with caste-specific differences in the haemolymph ecdysteroid titer. In vitro exposure of larval worker ovaries to physiological (10 M) concentrations of synthetic makisterone A elicited an identical response. Juvenile hormone did not affect protein synthesis patterns in larval ovaries, and also did not inhibit or reverse the ecdysteroid-induced effects. Heat shock experiments revealed that the 29 kDa/pI 4.6 ecdysteroid-regulated protein belongs to the class of small heat shock proteins.

Juvenile hormone, reproduction, and worker behavior in the neotropical social waspPolistes canadensis

“…JH titer should be seen as one factor among several that can affect the highly plastic task performance of social insect workers (4,13,71). Others, such as ecdysteroids, are known to correlate, along with JH titer, with degree of ovarian development in P. gallicus (20) and B. terrestris (72,73) but not in highly eusocial bees (74).…”

A member of the short-chain dehydrogenase/reductase (SDR) superfamily is a target of the ecdysone response in honey bee (Apis mellifera) caste development

“…Gel-loading controls are represented by ethidium bromidestained 28S rRNA. of this stage corresponded to the in vivo characteristics in ecdysteroid-regulated protein synthesis (Hartfelder et al, 1995). In the Northern blots of ovary RNA extracts this ecdysone response was clearly visible in the near complete reduction of SDR expression as a result of a 6 h exposure to 5 × 10 -7 M makisterone A (Fig.…”

“…5 × 10 -7 M) (Hartfelder et al, 1995). Control ovaries were incubated for the same time without hormone.…”

“…report of caste-specific differences in the synthesis of two ecdysteroid-regulated proteins in the larval honey bee ovary (Hartfelder et al, 1995). These two ecdysteroid-regulated proteins were detected by two-dimensional fluorography analysis of ovarian proteins synthesized in the presence or absence of makisterone A.…”

RNAs de fita dupla oferecidos na dieta de larvas causam alterações fisiológicas no desenvolvimento das castas de Apis mellifera

“…Em larvas de operárias naturais observou-se apoptose dos ovaríolos, dado o menor título de hormônio juvenil circulante (Schmidt-Capella e Hartfelder, , 2002. Do ponto de vista funcional, estudos em larga-escala demonstraram que o perfil global de expressão gênica em larvas de rainhas e operárias de A. mellifera é bastante distinto e, em particular, apresenta genes diferencialmente expressos ligados a processos metabólicos, nutricionais, de sinalização e hormônio-dependentes durante o desenvolvimento (Severson et al, 1989;Hartfelder et al 1995;Corona et al, 1999;Evans e Wheeler, 1999, 2000Hepperle e Hartfelder, 2001), evidenciando forte pressão seletiva direcional (Evans e Wheeler, 2000).…”