Chemical sensing of DNT by engineered olfactory yeast strain

With the increasing threat of environmental toxicants including biological and chemical warfare agents, fabricating innovative biomimetic systems to detect these harmful agents is critically important. With the broad objective of developing such a biosensor, here we report the construction of a Saccharomyces cerevisiae strain containing the primary components of the mammalian olfactory signaling pathway. In this engineered yeast strain, WIF-1alpha, olfactory receptor signaling is coupled to green fluorescent protein expression. Using this 'olfactory yeast', we screened for olfactory receptors that could report the presence of the odorant 2,4-dinitrotoluene, an explosive residue mimic. With this approach, we have identified the novel rat olfactory receptor Olfr226, which is closely related to the mouse olfactory receptors Olfr2 and MOR226-1, as a 2,4-dinitrotoluene-responsive receptor.     

Equilibrium Between Dimeric and Monomeric Forms of Human Epidermal Growth Factor is Shifted Towards Dimers in a Solution

The Protein Journal - An interplay between monomeric and dimeric forms of human epidermal growth factor (EGF) affecting its interaction with EGF receptor (EGFR) is poorly understood. While EGF...     

The invasive crayfish Faxonius immunis causes the collapse of macroinvertebrate communities in Central European ponds

Aquatic Ecology - The invasive crayfish Faxonius immunis is regarded as a threat to amphibians and macroinvertebrates in the Upper Rhine Valley, Germany, eradicating macrophytes and establishing...     

Correlated divergence of female and male genitalia in replicated lineages with ongoing ecological speciation

Divergence of genital traits among lineages has the potential to serve as a reproductive isolating barrier when copulation, insemination, and fertilization are inhibited by incompatibilities between female and male genitalia. Despite widespread evidence for genital trait diversity among closely related lineages and coevolution of female and male genitalia within lineages, few studies have investigated genital evolution during the early stages of speciation. We quantified genital variation in replicated population pairs of Poecilia mexicana with ongoing ecological speciation between sulfidic (H₂S containing) and nearby nonsulfidic habitats. These analyses revealed rapid and correlated divergence of female and male genitalia across evolutionarily independent population pairs exposed to divergent selection regimes. Both sexes exhibited convergent evolution of genital traits among populations inhabiting similar habitat types. Our results demonstrate that genital evolution can occur during the early stages of speciation‐with‐gene‐flow, potentially as a result of variation in the intensity of sexual conflict among populations. Our results suggest genitalia may contribute to early stages of divergence and challenge the generality of previously suggested mechanisms of genital evolution in poeciliids.     

Nutrient recycling by insect and fish communities in high-elevation tropical streams

Hydrobiologia - High- to mid-elevation streams are often oligotrophic, but harbor diverse groups of aquatic animals that can satisfy a substantial proportion of nutrient demand. Therefore, we...     

The impacts of introduced House Mice on the breeding success of nesting seabirds on Gough Island

Invasive species are the main threat to island biodiversity; seabirds are particularly vulnerable and are one of the most threatened groups of birds. Gough Island, a UNESCO World Heritage Site in the South Atlantic Ocean, is an Important Bird and Biodiversity Area, and one of the most important seabird colonies globally. Invasive House Mice Mus musculus depredate eggs and chicks of most seabird species on the island, but the extent of their impact has not been quantified. We used field data and bootstrapped normal distributions to estimate breeding success and the number of surviving chicks for 10 seabird species on Gough Island, and compared estimates with those of analogous species from predator‐free islands. We examined the effects of season and nest‐site location on the breeding success of populations on Gough Island, predicting that the breeding success of Gough birds would be lower than that of analogues, particularly among small burrow‐nesting species. We also predicted that winter‐breeding species would exhibit lower breeding success than summer‐breeding species, because mice have fewer alternative food sources in winter; and below‐ground nesters would have lower breeding success than surface nesters, as below‐ground species are smaller so their chicks are easier prey for mice. We did indeed find that seabirds on Gough Island had low breeding success compared with analogues, losing an estimated 1 739 000 (1 467 000–2 116 000) eggs/chicks annually. Seven of the 10 focal species on Gough Island had particularly high chick mortality and may have been subject to intense mouse predation. Below‐ground and winter breeders had lower breeding success than surface‐ and summer‐breeders. MacGillivray's Prion Pachyptila macgillivrayi, Atlantic Petrel Pterodroma incerta and Tristan Albatross Diomedea dabbenena are endemic or near‐endemic to Gough Island and are likely to be driven to extinction if invasive mice are not removed.     

Structural and functional properties of αβ-heterodimers of tropomyosin with myopathic mutations Q147P and K49del in the β-chain

Tropomyosin (Tpm) is an α-helical coiled-coil actin-binding protein that plays a key role in the Ca²⁺-regulated contraction of striated muscles. Two Tpm isoforms, α (Tpm 1.1) and β (Tpm 2.2), are expressed in fast skeletal muscles. These Tpm isoforms can form either αα and ββ homodimers, or αβ heterodimers. However, only αα-Tpm and αβ-Tpm dimers are usually present in most of fast skeletal muscles, because ββ-homodimers are relatively unstable and cannot exist under physiologic conditions. Nevertheless, the most of previous studies of myopathy-causing mutations in the Tpm β-chains were performed on the ββ-homodimers. In the present work, we applied different methods to investigate the effects of two myopathic mutations in the β-chain, Q147P and K49del (i.e. deletion of Lys49), on structural and functional properties of Tpm αβ-heterodimers and to compare them with the properties of ββ-homodimers carrying these mutations in both β-chains. The results show that the properties of αβ-Tpm heterodimers with these mutations in the β-chain differ significantly from the properties of ββ-homodimers with the same substitutions in both β-chains. This indicates that the αβ-heterodimer is a more appropriate model for studying the effects of myopathic mutations in the β-chain of Tpm than the ββ-homodimer which virtually does not exist in human skeletal muscles.