Juvenile hormone as a causal factor for maternal regulation of diapause in a wasp.

Most temperate multivoltine insects enter diapause, a hormonally controlled developmental suspension, in response to seasonal photoperiodic and/or thermal cues. Some insect species exhibit maternal regulation of diapause in which developmental trajectories of the offspring are determined by mothers in response to environmental cues that the mother received. Although maternally regulated diapause is common among insects, the maternal endocrinological mechanisms are largely veiled. To approach this issue, we used the jewel wasp Nasonia vitripennis, which produces non-diapause-destined offspring under long days and diapause-destined offspring under short days or low temperatures. Comparative transcriptomics of these wasps revealed possible involvement of the juvenile hormone (JH) biosynthetic cascade in maternal diapause regulation. The expression of juvenile hormone acid O-methyltransferase (jhamt) was typically downregulated in short-day wasps, and this was reflected by a reduction in haemolymph JH concentrations. RNAi targeted at jhamt reduced haemolymph JH concentration and induced wasps to produce diapause-destined offspring even under long days. In addition, topical application of JH suppressed the production of diapause-destined offspring under short days or low temperatures. These results indicate that diapause in N. vitripennis is determined by maternal jhamt expression and haemolymph JH concentration in response to day length. We therefore report a novel role for JH in insect seasonality.

Urban warming and artificial light alter dormancy in the flesh fly.

Seasonal changes in temperature and day length are distinct between rural and urban areas due to urban warming and the presence of artificial light at night. Many studies have focused on the impacts of these ubiquitous signatures on daily biological events, but empirical studies on their impacts on insect seasonality are limited. In the present study, we used the flesh fly Sarcophaga similis as a model insect to determine the impacts of urbanization on the incidence and timing of diapause (dormancy), not only in the laboratory but also in rural and urban conditions. In the laboratory, diapause entry was affected by night-time light levels as low as 0.01 lux. We placed fly cages on outdoor shelves in urban and rural areas to determine the timing of diapause entry; it was retarded by approximately four weeks in urban areas relative to that in rural areas. Moreover, almost all flies in the site facing an urban residential area failed to enter diapause, even by late autumn. Although an autumnal low temperature in the urban area would mitigate the negative effect of artificial light at night, strong light pollution seriously disrupts the flesh fly seasonal adaptation.

Cell cycle arrest in the jewel wasp Nasonia vitripennis in larval diapause.

Insects enter diapause to synchronise their life cycle with biotic and abiotic environmental conditions favourable for their development, reproduction, and survival. One of the most noticeable characteristics of diapause is the blockage of ontogeny. Although this blockage should occur with the cessation of cellular proliferation, i.e. cell cycle arrest, it was confirmed only in a few insect species and information on the molecular pathways involved in cell cycle arrest is limited. In the present study, we investigated developmental and cell cycle arrest in diapause larvae of the jewel wasp Nasonia vitripennis. Developmental and cell cycle arrest occur in the early fourth instar larval stage of N. vitripennis under short days. By entering diapause, the S fraction of the cell cycle disappears and approximately 80% and 20% of cells arrest their cell cycle in the G0/G1 and G2 phases, respectively. We further investigated expression of cell cycle regulatory genes and some housekeeping genes to dissect molecular mechanisms underlying the cell cycle arrest.

Bilateral epididymal sarcoidosis presenting without radiographic evidence of intrathoracic lesion: Review of sarcoidosis involving the male reproductive tract.

Sarcoidosis is a multisystem disorder that rarely involves the genitourinary tract. To date, only 59 cases of histologically proven sarcoidosis involving the male reproductive tract have been reported in the literature. We present here a case of bilateral epididymal sarcoidosis without radiographic evidence of intrathoracic lesion. A 46-year-old man presented with a one-week history of painless bilateral scrotal swellings. Physical examination detected multiple elastic firm nodules on both sides of the scrotum which showed no tenderness. The nodules seemed to involve the entire bilateral epididymides. Some irregularly shaped hypoechoic masses in the bilateral epididymides were identified on gray scale ultrasonography. On magnetic resonance images, the bilateral epididymides were seen to be enlarged, heterogeneous and nodular without any signs of testicular involvement. The lesion showed a slightly high signal intensity on the T2-weighted image. Pathological evaluation following bilateral epididymectomy found non-caseating epithelioid cell granulomas with giant cells in epididymal tissue, thus confirming a diagnosis of sarcoidosis. Gallium-67 scanning showed additional small hot spots in the anterior chest wall and extremities. Open biopsy of a superficial papular lesion in the dermis of the right upper arm was performed and pathological findings indicated sarcoid granulomas. This report also includes a review of the literature pertaining to sarcoidosis of the male reproductive tract.