Corticosterone stimulates hatching of late-term tree lizard embryos

The regulation of hatching in oviparous animals is important for successful reproduction and survival, but is poorly understood. We unexpectedly found that RU-486, a progesterone and glucocorticoid antagonist, interferes with hatching of viable tree lizard (Urosaurus ornatus) embryos in a dose-dependent manner and hypothesized that embryonic glucocorticoids regulate hatching. To test this hypothesis, we treated eggs with corticosterone (CORT) or vehicle on Day 30 (85%) of incubation, left other eggs untreated, and observed relative hatch order and hatch time. In one study, the CORT egg hatched first in 9 of 11 clutches. In a second study, the CORT egg hatched first in 9 of 12 clutches, before vehicle-treated eggs in 10 of 12 clutches, and before untreated eggs in 7 of 9 clutches. On average, CORT eggs hatched 18.2 h before vehicle-treated eggs and 11.6 h before untreated eggs. Thus, CORT accelerates hatching of near-term embryos and RU-486 appears to block this effect. CORT may mobilize energy substrates that fuel hatching and/or accelerate lung development, and may provide a mechanism by which stressed embryos escape environmental stressors.     

Deceived,but not betrayed: static allometry suggests female ornaments in the long-tailed dance fly (Rhamphomyia longicauda) exaggerate condition to males

Evolutionary Ecology - Despite their prevalence in nature, the evolution of sex-specific female ornaments is still not well understood. Although in some cases (often carotenoid-based ornaments)...     

Two new Ig VH gene families in Oncorhynchus mykiss

Genes encoding the immunoglobulin heavy-chain variable region (Ig VH) in rainbow trout (Oncorhynchus mykiss) have been grouped into 11 families. While obtaining a baseline assessment of the various gene families utilized by trout in the production of secreted antibody, we discovered two new families. These proposed Ig VH families, Families XII and XIII, were rarely observed; only two VH sequence types were detected for each new family, suggesting that they may not be commonly used in response to antigens, or that the captive environment may not lead to typical exposures seen in the wild. Additionally, unlike preceding studies, we found at least one representative gene sequence for each of the 11 reported Ig VH gene families, possibly indicating that the repertoire of trout Ig VH gene families may be more universal among different stocks than previously realized. GenBank accession numbers: Family XII—DQ453185 and DQ453150; Family XIII—DQ453153 and DQ453146; others DQ453143, DQ453156, DQ831723, DQ831825.     

Pairing and insemination patterns in a giant weta (Deinacrida rugosa: Orthoptera; Anostostomatidae)

Positive size assortative mating can arise if either one or both sexes prefer bigger mates or if the success of larger males in contests for larger females leaves smaller males to mate with smaller females. Moreover, body size could not only influence pairing patterns before copulation but also the covariance between female size and size of ejaculate (number of spermatophores) transferred to a mate. In this field study, we examine the pre-copulatory mate choice, as well as insemination, patterns in the Cook Strait giant weta (Deinacrida rugosa). D. rugosa is a large orthopteran insect that exhibits strong female-biased sexual dimorphism, with females being nearly twice as heavy as males. Contrary to the general expectation of male preference for large females in insects with female-biased size dimorphism, we found only weak support for positive size assortative mating based on size (tibia length). Interestingly, although there was no correlation between male body size and the number of spermatophores transferred, we did find that males pass more spermatophores to lighter females. This pattern of sperm transfer does not appear to be a consequence of those males that mate heavier females being sperm depleted. Instead, males may provide lighter females with more spermatophores perhaps because these females pose less of a sperm competition risk to mates.     

Prokaryote multidrug efflux proteins of the major facilitator superfamily: amplified expression, purification and characterisation

In bacterial genomes 3-12% of open reading frames are predicted to encode membrane transport proteins. These proteins can be vital for antibiotic efflux, protein/ toxin secretion, cell nutrition, environmental sensing, ATP synthesis, and other functions. Some, such as the multidrug efflux proteins, are potential targets for the development of new antibacterials and also for applications in biotechnology. In general membrane transport proteins are poorly understood, because of the technical difficulties involved in isolating sufficient protein for elucidation of their structure-activity relationships. We describe a general strategy for the amplified expression, purification and characterisation of prokaryotic multidrug efflux proteins of the 'Major facilitator superfamily' of transport proteins, using the Bacillus subtilis multidrug resistance protein, 'Bmr', as example.