Mutations in voltage-gated sodium channels from pyrethroid resistant salmon lice (Lepeophtheirus salmonis)

Background Parasitic salmon lice (Lepeophtheirus salmonis) cause high economic losses in Atlantic salmon farming. Pyrethroids, which block arthropod voltage‐gated sodium channels (Nav1), are used for salmon delousing. However, pyrethroid resistance is common in L. salmonis. The present study characterised Nav1 homologues in L. salmonis in order to identify channel mutations associated to resistance, called kdr (knockdown) mutations. Results Genome scans identified three L. salmonis Nav1 homologues, LsNav1.1, LsNav1.2 and LsNav1.3. Arthropod kdr mutations map to specific Nav1 regions within domains DI‐III, namely segments S5 and S6 and the linker helix connecting S4 and S5. The above channel regions were amplified by RT‐PCR and sequenced in deltamethrin‐susceptible and deltamethrin‐resistant L. salmonis. While LsNav1.1 and LsNav1.2 lacked nucleotide polymorphisms showing association to resistance, LsNav1.3 showed a non‐synonymous mutation in S5 of DII occurring in deltamethrin‐resistant parasites. The mutation is homologous to a previously described kdr mutation (I936V, numbering according to Musca domestica Vssc1) and was present in two pyrethroid‐resistant L. salmonis strains (allele frequencies of 0.800 and 0.357), but absent in two pyrethroid‐susceptible strains. Conclusions The present study indicates that a kdr‐mutation in LsNaV 1.3 may contribute to deltamethrin resistance in L. salmonis

Life-Course Genome-wide Association Study Meta-analysis of Total Body BMD and Assessment of Age-Specific Effects.

Bone mineral density (BMD) assessed by DXA is used to evaluate bone health. In children, total body (TB) measurements are commonly used; in older individuals, BMD at the lumbar spine (LS) and femoral neck (FN) is used to diagnose osteoporosis. To date, genetic variants in more than 60 loci have been identified as associated with BMD. To investigate the genetic determinants of TB-BMD variation along the life course and test for age-specific effects, we performed a meta-analysis of 30 genome-wide association studies (GWASs) of TB-BMD including 66,628 individuals overall and divided across five age strata, each spanning 15 years. We identified variants associated with TB-BMD at 80 loci, of which 36 have not been previously identified; overall, they explain approximately 10% of the TB-BMD variance when combining all age groups and influence the risk of fracture. Pathway and enrichment analysis of the association signals showed clustering within gene sets implicated in the regulation of cell growth and SMAD proteins, overexpressed in the musculoskeletal system, and enriched in enhancer and promoter regions. These findings reveal TB-BMD as a relevant trait for genetic studies of osteoporosis, enabling the identification of variants and pathways influencing different bone compartments. Only variants in ESR1 and close proximity to RANKL showed a clear effect dependency on age. This most likely indicates that the majority of genetic variants identified influence BMD early in life and that their effect can be captured throughout the life course

The upper lithostratigraphic unit of ANDRILL AND-2A core (Southern McMurdo Sound, Antarctica): Local Pleistocene volcanic sources, paleoenvironmental implications and subsidence in the southern Victoria Land Basin

We report results from the study of the uppermost 37 m of the Southern McMurdo Sound (SMS) AND-2A drill core, corresponding to the lithostratigraphic unit 1 (LSU 1), the most volcanogenic unit within the core. We present data on the age, composition, volcanological and depositional features of the volcanic sedimentary and tephra deposits of LSU 1 and discuss their source, mechanisms of emplacement and environment of deposition. Sedimentary features and compositional data indicate shallow water sedimentation for the whole of LSU 1. Most of LSU 1 deposits are a mixture of near primary volcanic material with minor exotic clasts derived from the Paleozoic crystalline basement rocks. Among volcanic materials, glassy particles are the most abundant. They were produced by mildly explosive basaltic eruptions occurring in subaerial and subaqueous environments. The Dailey Islands group, 13 km south-southwest of the SMS drill-site, has been identified as a possible source for the volcanics on the basis of similarity in composition and age. 40Ar–39Ar laser step-heating analyses on a lava sample from Juergens Island yields an age of 775 ± 22 ka. Yet because of the minimal reworking features of vitriclasts, preservation of fragile structures in volcaniclastic sediments and evidence for volcanic seamounts to the north of the Dailey Islands, it is likely that some of the material originated also from vents close to the drill-site. Evidence for local volcanic sources and for deposition of sediments in a shallow marine environment provides indications about the local paleogeography and implications for the subsidence history of the southern Victoria Land Basin from Pleistocene to Recent

Female Crayfish Mate Preference Concerning Male Dominance

Male crayfish Orconectes quinebaugensis compete for dominance, therefore, we hypothesized that male dominance correlates with female mate choice, resulting in dominant males being chosen for more reproductive encounters. It was found that the dominance score earned by each male was significantly correlated to its claw size and that there was no significant correlation between the time females spent in the male-containing arm of a Y-maze and their time spent in a control arm. Analysis of our data indicates no relationship between a male's dominance and a female's mate preference