Mitochondrial and nuclear markers reveal a lack of genetic structure in the entocommensal nemertean Malacobdella arrokeana in the Patagonian gulfs

Abstract Malacobdella arrokeana is an entocommensal nemertean exclusively found in the bivalve geoduck Panopea abbreviata, and it is the only representative of the genus in the southern hemisphere. To characterize its genetic diversity, population structure and recent demographic history, we conducted the first genetic survey on this species, using sequence data for the cytochrome oxidase I gene (COI), 16S rRNA (16S) and the internal transcribed spacer (ITS2). Only four different ITS2 genotypes were found in the whole sample, and the two main haplotypes identified in the mitochondrial dataset were present among all localities with a diversity ranging from 0.583 to 0.939. Nucleotide diversity was low (p = 0.001?0.002). No significant genetic structure was detected between populations, and mismatch distribution patterns and neutrality tests results are consistent with a population in expansion or under selection. Analysis of molecular variance (AMOVA) revealed that the largest level of variance observed was due to intrapopulation variation (100, 100 and 94.39 % for 16S, COI and ITS2, respectively). Fst values were also non-significant. The observed lack of population structure is likely due to high levels of genetic connectivity in combination with the lack or permeability of biogeographic barriers and episodes of habitat modification.Fil: Fernandez Alfaya, Jose Elias. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Nacional Patagónico; ArgentinaFil: Bigatti, Gregorio. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Nacional Patagónico; ArgentinaFil: Machordom, Annie. Consejo Superior de Investigaciones Cientificas. Museo Nacional de Cs. Naturales; Españ

Accelerated discovery of two crystal structure types in a complex inorganic phase field

The discovery of new materials is hampered by the lack of efficient approaches to the exploration of both the large number of possible elemental compositions for such materials, and of the candidate structures at each composition1. For example, the discovery of inorganic extended solid structures has relied on knowledge of crystal chemistry coupled with time-consuming materials synthesis with systematically varied elemental ratios2,3. Computational methods have been developed to guide synthesis by predicting structures at specific compositions4,5,6 and predicting compositions for known crystal structures7,8, with notable successes9,10. However, the challenge of finding qualitatively new, experimentally realizable compounds, with crystal structures where the unit cell and the atom positions within it differ from known structures, remains for compositionally complex systems. Many valuable properties arise from substitution into known crystal structures, but materials discovery using this approach alone risks both missing best-in-class performance and attempting design with incomplete knowledge8,11. Here we report the experimental discovery of two structure types by computational identification of the region of a complex inorganic phase field that contains them. This is achieved by computing probe structures that capture the chemical and structural diversity of the system and whose energies can be ranked against combinations of currently known materials. Subsequent experimental exploration of the lowest-energy regions of the computed phase diagram affords two materials with previously unreported crystal structures featuring unusual structural motifs. This approach will accelerate the systematic discovery of new materials in complex compositional spaces by efficiently guiding synthesis and enhancing the predictive power of the computational tools through expansion of the knowledge base underpinning them

Influence of neighborhood-level socioeconomic deprivation and individual socioeconomic position on risk of developing type 2 diabetes in older men: a longitudinal analysis in the British Regional Heart Study cohort.

INTRODUCTION: Evidence from longitudinal studies on the influence of neighborhood socioeconomic deprivation in older age on the development of type 2 diabetes mellitus (T2DM) is limited. This study investigates the prospective associations of neighborhood-level deprivation and individual socioeconomic position (SEP) with T2DM incidence in older age. RESEARCH DESIGN AND METHODS: The British Regional Heart Study studied 4252 men aged 60-79 years in 1998-2000. Neighborhood-level deprivation was based on the Index of Multiple Deprivation quintiles for participants' 1998-2000 residential postcode. Individual SEP was defined as social class based on longest-held occupation. A cumulative score of individual socioeconomic factors was derived. Incident T2DM cases were ascertained from primary care records; prevalent cases were excluded. Cox proportional hazard models were used to examine the associations. RESULTS: Among 3706 men, 368 incident cases of T2DM were observed over 18 years. The age-adjusted T2DM risk increased from the least deprived quintile to the most deprived: HR per quintile increase 1.14 (95% CI 1.06 to 1.23) (p=0.0005). The age-adjusted T2DM HR in social class V (lowest) versus social class I (highest) was 2.45 (95% CI 1.36 to 4.42) (p=0.001). Both associations attenuated but remained significant on adjustment for other deprivation measures, becoming non-significant on adjustment for body mass index and T2DM family history. T2DM risk increased with cumulative individual adverse socioeconomic factors: HR per point increase 1.14 (95% CI 1.05 to 1.24). CONCLUSIONS: Inequalities in T2DM risk persist in later life, both in relation to neighborhood-level and individual-level socioeconomic factors. Underlying modifiable risk factors continue to need to be addressed in deprived older age populations to reduce disease burden