Division of labor in social insect colonies relies on a strong reproductive bias that favors queens. Although the ecological and evolutionary success attained through caste systems is well sketched out in terms of ultimate causes, the molecular and cellular underpinnings driving the development of caste phenotypes are still far from understood. Recent genomics approaches on honey bee developmental biology revealed a set of genes that are differentially expressed genes in larval ovaries and associated with transgressive ovary size in queens and massive cell death in workers. Amongst these, two contigs called special attention, both being over 200 bp in size and lacking apparent coding potential. Herein, we obtained their full cDNA sequences. These and their secondary structure characteristics placed in evidence that they are bona fide long noncoding RNAs (lncRNA) differentially expressed in larval ovaries, thus named lncov1 and lncov2. Genomically, both map within a previously identified QTL on chromosome 11, associated with transgressive ovary size in honey bee workers. As lncov1 was over-expressed in worker ovaries we focused on this gene. Real-time qPCR analysis on larval worker ovaries evidenced an expression peak coinciding with the onset of autophagic cell death. Cellular localization analysis through fluorescence in situ hybridization revealed perinuclear spots resembling omega speckles known to regulate trafficking of RNA-binding proteins. With only four lncRNAs known so far in honey bees, two expressed in the ovaries, these findings open a novel perspective on regulatory factors acting in the fine tuning of developmental processes underlying phenotypic plasticity related to social life histories.

The strong dimorphism in ovary phenotype seen between honey bee queens and workers represents the anatomical fixation of reproductive division of labor. We review the developmental processes by which the divergent ovary phenotypes become established, mainly focusing on the massive programmed cell death (PCD) that destroys most of the ovariole primordia in the worker ovary during larval development. Ovary-specific transcriptome analyses revealed a set of differentially expressed genes associated with PCD, including two long noncoding RNAs. PCD also plays a major role regulating ovarian activity in adult honey bee workers, and a major effect candidate gene mediating this process is Anarchy , previously identified through classical genetics in a rebel worker strain. Finally, we ask how the strong ovary phenotype dimorphism in the genus Apis may have evolved, and we discuss this by contrasting honey bees with the equally eusocial stingless bees. Through a comparison of their mating systems (polyandry versus monandry), as well as comparative data on female and male gonad structure across several families of bees, we propose the hypothesis that the exceptional gonad structure in Apis queens and drones evolved via shared developmental pathways. Furthermore, we suggest that selection on massive sperm production in Apis drones may have been a driving force leading to this exaggerated gonad morphology. honeybee / gonad development / cell death / differential gene expression / meliponids Where does the spirit of the hive reside? At least to some extent it is in the ovaries of a crowd of bees working in a dark hive (Robert E.

The 20 reported cases of MZ female twins discordant for X-linked diseases are reviewed. In such twins the X-inactivation pattern is opposite skewing (abnormal allele inactivated in most cells of the normal twin, and normal allele inactivated in most cells of the affected twin) or skewing in one twin and random in the cotwin. The diseases involved map in two specific regions: Xq27-28 and Xp21. The only exceptions are Fabry's disease and Aicardi's syndrome, which map in Xq22 and Xp22 respectively. No concordant MZ female carrier twins, either normal or affected, have been described. Three main hypotheses have been proposed to explain such characteristics [2, 5, 14], but none is completely satisfactory. The constant discordance for X-linked diseases in MZ female twins has important consequences for genetic counselling.

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SUMMARYInsect sociality is a major evolutionary transition based on the suppression of worker reproduction in favor of the reproductive monopoly of the queen. In the honey bee (Apis mellifera) model organism, the development of the two female caste phenotypes, queen and worker, is triggered by differences in their larval diets. However, the mechanistic details underlying their respective developmental trajectories, as well as the maintenance of sterility in the adult workers, are still not fully understood. Here we show that the long non-coding RNA lncov1 interacts with the Tudor staphylococcus nuclease (Tudor-SN) protein to form a regulatory module that promotes apoptosis in the ovaries of worker larvae. In adult workers, the lncov1/Tudor-SN module responds positively to environmental cues that suppress reproductive capacity. As lncov1 is considerably conserved in the Apidae, we propose that, by promoting worker sterility, the lncov1/Tudor-SN module has likely played critical roles in the social evolution of bees.