What is the matter with Corbicula fluminea (Mollusca: Bivalvia: Cyrenidiae)? Occurrence of unusual shell erosion in Northern Italy

ABSTRACT

Corbicula fluminea is a bivalve considered to be among the 100 worst invasive species in Europe due to its economic and ecological impacts in freshwater ecosystems. Here, we report for the first time a phenomenon of shell erosion observed in two distinct populations of C. fluminea collected in 2015 from two semi-natural small streams of the River Ticino hydrographic basin (Northern Italy). We measured several biometric variables in order to quantify the shell damage: length and thickness of the right valve and the shell free dry weight of each specimen and compared results with those of ‘normal’ populations from another stream of the same area. Our results confirmed that there was abnormal shell erosion and a reduction in shell thickness in both populations. We hypothesised several potential causes for the observed erosion, but none of them could provide sufficient explanation: neither the pH of the water, nor the level of calcium or total hardness of the water or granulometry of the substrates differed among streams. Similarly, predation pressure cannot be considered a reasonable explanation, since in the study area only a few animals actively prey on these bivalves and the marks they leave on the shells are completely different from the ones observed on our specimens. Lastly, we hypothesised that the bivalves may have been affected by a disease or parasitic infestation that had weakened their shells or prevented them from self-repairing and identified a fungal parasite that could possibly cause a disease to C. fluminea, namely the Ascomycota Geotrichum candidum. However, this species occurred only in one of the two abnormally eroded populations. In conclusion, a valid explanation for the morphological alteration that our study revealed has yet to be found.     

闽江某河段河蚬组织中多环芳烃和有机氯农药的蓄积特征

用GC／MS和GC-μECD测定了闽江某河段河蚬体内多环芳烃（PAHs）和有机氯农药（OCPs）的含量，并分析了河蚬各器官组织中的蓄积特征．结果表明：河蚬体内鳃、肌肉以及内脏团中检测到的PAHs的总量分别为1322．03，397．24，951．04ng／g干重，河蚬易累积低分子量的PAHs，主要是3环PAHS，鳃、肌肉和内脏团中检测到的3环芳烃的比率分别为62．23％，47．04％和36．96％；河蚬对OCPs的蓄积种类主要是DDT类和HCH类农药，OCPs在河蚬鳃、肌肉以及内脏团中的总含量相差不大，分别为19．73，25．46，23．06ng／g干重，河蚬肌肉和内脏团中OCPs的含量与整体中OCPs的含量相关性较好（R^2=0．98和R^2=0．98），肌肉中含量与整体有机氯的含量相关系数为R^2=0．19．     

飞龙掌血水提物的扩血管作用及原理初探

飞龙掌血的水提物飞龙一号(F01)给小鼠腹腔注射,其 LD_(50)=3.70g/kg。F01(80mg/kg)对麻醉 S.D.大鼠有明显降血压作用,伴有心率加快。该作用无快速耐受性,且不被 H_1及 H_2组胺受体、M 胆碱受体及β肾上腺素受体之阻断剂取消。对于离体 S.D.大鼠尾动脉螺旋条,F01(0.3至3mg/ml)可使由 KCl(60mmol/L)、NE(0.1μmol/L)或 AVP(0.01μmol/L)刺激而收缩的组织明显舒张。KCI(80mmol/L)增加血管平滑肌组织对钙的撮取,这可以通过测定组织中未被镧置换的低亲和力同位素~(45)Ca 的含量来确定。F01(0.06至4mg/ml)可显著降低这种钙摄取的增加。上述结果表明,F01具有直接扩张血管作用,此种作用与抑制钙内流有关。     

Prey selection by the critically endangered Asiatic cheetah in central Iran

The presence of the critically endangered Asiatic cheetah (Acinonyx jubatus venaticus) has been verified in several protected areas in central Iran. Prey selection by the Asiatic cheetah was studied in Dare-Anjir Wildlife Refuge, one of its typical habitats in central Iran where there are no carnivorous competitors. The frequency of cheetah kills was compared with the relative abundance of each of its primary prey species obtained through two independent surveys. Jebeer gazelle (Gazella bennettii) was least abundant, but was the preferred prey of cheetah, whereas wild sheep (Ovis orientalis) followed by Persian ibex (Capra aegagrus) were the most frequently killed prey. Cheetahs selectively preyed on males of the three prey species. Our data suggest that Asiatic cheetahs prey mainly on mountain ungulates (wild sheep and Persian ibex), which has management implications for effective conservation of this taxon in Iran.     

近红外漫反射光谱法对吉林人参的分类探讨

将近红外光谱技术与计算机结合 ,采用漫反射光学检测方法 ,对吉林省产的西洋参、人参及其炮制品红参进行分析 ,应用系统聚类法获得分类结果 ,探讨近红外光谱鉴别中药材的一种新思路     

The status and conservation of the Asiatic black bear in Nikshahr County,Baluchistan District of Iran

Little information exists on the Asiatic black bear (Ursus thibetanus gerdrosianus) in the western part of its distribution. This study investigated the status of this species in the Baluchistan district of Iran, from April 2004 to February 2006. Sign surveys and interviews with elderly local‐born people revealed that although this bear was commonly seen by locals in many areas 20–30 years ago, at present, it only exists in four localities in Nikshahr County (Aband, Kushad, Shoshin and the Pozak Protected Area). Each of these four areas appears to be occupied by only a few individual bears. It seems that the largest number of black bear live in the Aband Mountains, followed by the Kushad Mountains, Shoshin and the Pozak Protected Area. Habitat fragmentation as the result of human habitation, livestock grazing and a continuous severe drought has caused insularization of these small bear populations in Nikshahr. The Asiatic black bear in Nikshahr is endangered in the entire area and is in need of urgent conservation action. The education and co‐operation of local people, and active management to restore habitat, are vital if this species is to persist in this region.     

所有制形式发展和共产主义的现实可能性

全社会共同占有生产资料是共产主义所有制的本质特征,从所有制形式发展的角度看,亚细亚所有制是孕育共产主义所有制的理想的前提;随后基于原始共同体的主体差异性和自然环境优劣性冲突、对立、融合而产生的古代所有制,是和共产主义相背离的;日耳曼所有制接受上述差异性和优劣性,便越来越远离共产主义所有制;生产力三要素对人类社会发展作用的拓展与转移,也使关于共产主义的具体规定性的描述成为先验理性的产物.像马克思那样将共产主义看作是一种"现实运动”,才是对共产主义信仰的正确理解.     

Mutual mate choice in the Asiatic toad, Bufo gargarizans, exerts stabilizing selection on body size

Sexual selection is critical to both reproduction and evolution.The effects of male–male competition and female choice regarding body size have been examined in a large number of taxa,including toad species.Males and females have different optimal reproductive strategies,achieving breeding advantages in discrepant ways.Further,the relative contributions of intra-and inter-sexual size selection vary among species.Thus,to understand the mechanisms affecting mating success,it is important to consider both male–male and male–female interactions simultaneously and elucidate their interrelationship.In this study,we measured body sizes of all mated and unmated individuals in a population of Asiatic toad(Bufo gargarizans)and counted fertilized eggs of several clutches.Based on correlation and regression techniques,we tested for female choice and intra-sexual competition among males relative to body size gradients,and we compared the relative importance of these two processes for mating success.Our results reveal that male–male competition and female choice simultaneously contribute to sexual selection in toads.Furthermore,both interactions are most intense among smaller toads.The synergistic trends of male–male competition and female choice support the mutual mate choice hypothesis and works to stabilize body size in B.gargarizans.Normal distributions of breeding success relative to body size were detected for both sexes,suggesting that medium-sized individuals enjoy a reproductive advantage in the population studied.