Reproductive isolation between Pogonomyrmex rugosus and two lineages with genetic caste determination

Hybrid speciation occurs when combination of two interspecific genomes results in individuals that are of high fitness but reproductively incompatible with the parental species. Although hybrid speciation is a relatively common source of new species in plants, it appears to be a much rarer occurrence in animal taxa. Here we report on reproductive isolation and range overlap between the rough harvester ant Pogonomyrmex rugosus and two lineages with hybrid genotypes (H 1 and H2). Both lineages obligately interbreed and produce genetically distinct queen and worker offspring, a phenomenon referred to as genetic caste determination (GCD). Diploid offspring produced by gametes of the same lineage develop only into queens, whereas diploid offspring derived from gametes of distinct lineages develop into workers. We investigated small-scale patterns of gene flow between the parent and the two H lineages by sampling along an 80-km transect between a pure P. rugosus population and a two-lineage population. Microsatellite and mitochondrial markers both indicated virtually no gene flow between the parent species and either lineage even at sites where parental and H-lineage colonies co-occurred. The geographic ranges of the parental species and the two-lineage population were essentially parapatric, with a surprisingly narrow band of overlap and evidence of spatial structuring even at microgeographic scales within the transition zone. This suggests that ecological competition with the parent species plays a significant role in determining the evolutionary persistence and current distribution of the hybrid lineages and the genetic caste system.     

单个药品及其混合物对Aliivibrio fischeri的毒性研究：单一化合物的实验结果，并对其行为机理和对水生生物潜在急性效应进行思考

在这个较广泛的关于单个和多组分混合药物活性化合物影响研究的第一部分,作者使用了Microtox^?测试系统详细分析了10种广泛使用的人用和兽用药活性化合物对生物荧光细菌Aliivibrio fischeri的影响。实验结果表明大多数受试化合物具有中度毒性。对比实验得到的50%抑制浓度和定量构效关系模型预测的结果表明,大多数受试药物活性化合物与极性麻醉型化合物对A. fischeri的行为类似(似乎只有抗生素金霉素有特定的作用机制)。将实验结果与其他不属预定目标的生物急性毒性数据集进行比较表明,一般而言A . fischeri较其他水生物种敏感。然而,根据全球化学品统一分类和标签制度,大部分受调查的化学物质可归为水生生态系统中有害或无毒的化合物。最后,基于欧盟水体中测量的环境浓度第95百分位数和各种水生生物的急性毒性数据的比较,可以认为当受试药物活性化合物作为单一化合物进行评估的时候,不存在水生生物风险。
精选自Valeria Di Nica, Sara Villa, Antonio Finizio. Toxicity of individual pharmaceuticals and their mixtures to Aliivibrio fischeri: experimental results for single compounds and considerations of their mechanisms of action and potential acute effects on aquatic organisms. Environmental Toxicology and Chemistry: Volume 36, Issue 3, pages 807–814, July 2017. DOI: 10.1002/etc.3568
详情请见http://onlinelibrary.wiley.com/wol1/doi/10.1002/etc.3568/full
     

Brain cortical assessment by MRI in fetuses with left congenital diaphragmatic hernia

Objective

To evaluate fetal brain development using MRI (magnetic resonance imaging) in CDH (congenital diaphragmatic hernia).

Methods

52 isolated left CDH and 104 control fetuses were imaged using MRI. Brain morphometry (Biparietal diameter—BPD, brain fronto-occipital diameter—BFOD, third ventricle, posterior ventricles, transcerebellar diameter—TCD, anteroposterior and craniocaudal cerebellar vermis diameter—AP and CC) and cortical structures (bilateral cingulate fissure—CF, insular fissure—IF, insular depth - ID) were compared with controls using Mann–Whitney test.

Results

Median gestational age at MRI (p = 0.95)and the median biparietal diameter (p = 0.737) were comparable. Among morphometric parameters, only the brain fronto-occipital diameter was significantly smaller in CDH (p = 0.001) and the third ventricle was significantly greater in CDH (<0.0001). Among cortical structures, the cingulate and insular fissures were significantly deeper in CDH fetuses (p < 0.0001) as the insular depth ID was smaller in CDH (p < 0.03).

Conclusions

CDH fetuses have a smaller fronto-occipital diameter, reduced insular depth, deeper cingulate and insular fissure, and greater third ventricle width as compared to controls. These findings suggest that left CDH may have an impact on fetal brain development with an overall reduction in brain volume.