Phorbol esters induce translocation of the nPKC p105 to membrane in mussel hemocytes

Previous works revealed the presence of the nPKC enzyme p105 in hemocytes of M. galloprovincialis Lmk. Specific mussel antibodies were obtained from mouse and used in confocal microscopy and Western blotting. These techniques allowed the observation of p105 cytosol-to-membrane translocation induced by TPA for the first time in hemocytes of molluscs. The incubation of mussel immune cells with TPA for longer than 30 min also triggered a down-regulation process. Mussel hemocytes are an excellent model to study the molecular processes of innate immunity.     

Cellular responses to increasing Cd concentrations in the freshwater crab,<Emphasis Type="Italic"> Potamonautes warreni</Emphasis>, harbouring microbial gill infestations

We investigated the uptake, transport, storage and defence mechanisms in the freshwater crab, Potamonautes warreni, harbouring microbial gill infestations and exposed to increasing chronic (0.2, 0.5, 1.0 mg l^–1) and acute (2.0 mg l^–1) cadmium (Cd) concentrations under controlled laboratory conditions over a period of 21 days. Transmission electron microscopy and X-ray microanalysis revealed that the microbial gill fauna was eliminated on exposure to 0.2 mg Cd²⁺ l^–1 and that Cd became increasingly adsorbed and incorporated into lamellar crystal deposits and permeated the cuticle of the gills of P. warreni. Degeneration of the apical membrane infoldings and vacuolation of epithelial cells occurred concurrently with pinocytosis, endocytosis and pronounced phagocytotic activity in the epithelia and haemal canal of the gills. Elevated Cd exposures (0.5 or 1.0 mg l^–1) resulted in the swelling and dissociation of mitochondrial outer membranes together with an increase in transport of Cu, Cl and S by haemocytes in the haemal canal to epithelial tissues depleted in these elements. Cd also accumulated in tightly coiled concentric membrane whorls in the haemal canal, whereas the highest concentrations of Cd were found within aggregates of lysosome-like bodies in cuticulin-secreting cells of the gill stem. Chronic exposure to Cd induced increased fatigue and mild uncoordinated motor activity. In contrast, at an acute exposure of 2.0 mg l^–1 over 48 h, P. warreni showed a time-specific rapid loss of motor function, although only mild cellular lesions occurred in the gill tissues. The significance of cellular changes in the gill epithelia and altered motor activity of P. warreni with increased waterborne Cd are discussed as potential biomarker responses in monitoring aquatic pollution.     

Seasonal change of seston size distribution and phytoplankton composition in bivalve pearl oyster Pinctada fucata martensii culture farm

Seasonal changes of seston were monitored in the pearl cultivation area of Uchiumi Bay, Ehime Prefecture, Japan where the pearl oyster Pinctada fucata martensii is cultivated. The concentrations of chlorophyll a and particulate carbon, nitrogen and phosphorus were measured and the community structure of the phytoplankton investigated between June 1997 and February 1999. The seston was divided into pico- (<2 m), nano- (2–20 m) and large (>20 m) size fractions. The dominant size fraction during the study period, <2 m (38.1–51.4%), is consumed by oyster larvae but is too small for the adult pearl oyster. During the summers of 1997 and 1998 Nitzschia spp. became dominant but is indigestible for the oyster which was thus subjected to food limitation. We suggest monitoring the composition of seston and phytoplankton >2 m for evaluation of the food environment of the pearl oyster.     

Proteome modifications of blue mussel (Mytilus edulis L.) gills as an effect of water pollution

The discharge of chemicals such as oil associated or not with derived products constitutes a real threat for the environment. We report here the differential expression of the blue mussel (Mytilus edulis) gill proteins corresponding to two contaminated environmental conditions: crude oil and offshore produced water. In order to evaluate and understand contaminants, effects and adaptive response of these organisms, we identified proteins using MS. The latter can be grouped into three main classes: proteins involved in the cellular structure, in metabolism, and in defence proteins.     

Pearl millet transformation system using the positive selectable marker gene phosphomannose isomerase

Fertile transgenic pearl millet plants expressing a phosphomannose isomerase (PMI) transgene under control of the maize ubiquitin constitutive promoter were obtained using the transformation system described here. Proliferating immature zygotic embryos were used as target tissue for bombardment using a particle inflow gun. Different culture and selection strategies were assessed in order to obtain an optimised mannose selection protocol. Stable integration of the manA gene into the genome of pearl millet was confirmed by PCR and Southern blot analysis. Stable integration of the manA transgene into the genome of pearl millet was demonstrated in T₁ and T₂ progeny of two independent transformation events with no more than four to ten copies of the transgene. Similar to results obtained from previous studies with maize and wheat, the manA gene was shown to be a superior selectable marker gene for improving transformation efficiencies when compared to antibiotic or herbicide selectable marker genes.Abbreviations 2,4-D: 2,4-Diclorophenoxyacetic acid - IAA: Indole acetic acid - ICRISAT: International Crops Research Institute for the Semi-Arid Tropics - IZEs Immature zygotic embryos Communicated by H. Lörz     

低盐度海水和淡水对中华绒螯蟹性腺发育及交配行为的影响

研究了低盐度海水(盐度为15)和淡水(盐度为0)对中华绒螯蟹(Eriocheir sinensis,以下简称河蟹)性腺发育及交配行为的影响,并比较了河蟹交配和产卵前后的性腺指数及肝胰腺指数的变化。实验分为4组,分别为低盐度海水雌蟹组、淡水雌蟹组、低盐度海水雄蟹组和淡水雄蟹组。结果表明,(1)各组河蟹的成活率均在80%左右,无显著差异(P>0.05);(2)实验第15天、30天和45天时,低盐度海水雌蟹组的卵巢指数显著高于淡水雌蟹组(P<0.05),低盐度海水雄蟹组的性腺指数也略高于淡水雄蟹组,但差异不显著(P>0.05);(3)实验第30天时,低盐度海水雌蟹组的肝胰腺指数显著低于淡水雌蟹组(P<0.05),其余采样时间两组雌体间或两组雄体间的肝胰腺指数差异不显著(P>0.05),实验期间,两组雌体的肝胰腺指数均显著下降(P<0.05);(4)实验第45天,低盐度海水雌蟹组和雄蟹组实验个体全部能够交配,有66.7%的低盐度海水雌蟹组的个体交配后2 d内产卵,淡水雄蟹组有部分个体在低盐度海水中有发情行为;(5)低盐度海水组,雌蟹产卵后和雄蟹交配后的性腺指数均显著下降(P<0.05),但肝胰腺指数下降不显著(P>0.05)。     

长江中下游湖泊贝类物种濒危状况评估

长江中下游是我国淡水贝类资源分布最为集中的地区.由于人类活动加剧,该区域贝类受到严重威胁.为系统评估贝类物种现状,于2003年5月至2005年6月对13个典型湖泊进行了系统调查.共采集贝类69种,其中中国特有种44种.不同类型湖泊贝类的组成差别较大.通江湖泊的物种明显较丰富,尤其是适应流水生境的种类,如河螺属、短沟蜷属及蚌科的种类.大型通江湖泊鄱阳湖和洞庭湖的贝类分别有53种和57种,占总数的76.8%和82.6%.阻隔湖泊的物种较少,在4-19种之间.对67种贝类濒危等级的评价结果表明,近危及受威胁的种类占58.2%,只有37.3%的种类种群稳定.与历史资料相比,该区域贝类的多样性已明显下降,双壳类优势类群由大型的蚌类演变为小型的河蚬.分析显示,贝类资源衰退的主要原因是江湖阻隔、过度捕捞和水体污染等人为干扰.     

环境DNA技术在贻贝入侵监测中的应用挑战

沼蛤(Limnoperna fortunei)和斑马贻贝(Dreissena polymorpha)是淡水系统中常见的入侵贻贝物种,对其种群规模的持续监测是入侵贻贝防治管控中的关键环节。随着分子生物学技术的发展,入侵物种监测中逐渐尝试利用环境DNA(eDNA)技术实现快速、灵敏检测。然而,在入侵物种引入-定植-扩散过程的监测中,eDNA技术的灵敏度及定量效果受到诸多因素的影响,给实际应用带来挑战。系统梳理了国内外学者利用eDNA技术监测沼蛤、斑马贻贝等入侵物种的研究进展;分析了eDNA技术的采样方案、引物设计、定量分析、质量保证、原位便携仪器设计等影响监测效率与准确率的关键环节;进一步探讨了eDNA技术在贻贝入侵监测中的优势和局限性,以及未来的改进方向。     

The impact of fish spawning on metal and protein levels in gastrointestinal cytosol of indigenous European chub

The study presented here reports for the first time cytosolic metal and protein levels in the gastrointestinal tissue of field-collected European chub (Squalius cephalus), living in low metal-contaminated river section. In two sub-cellular fractions (untreated cytosol and heat-treated cytosol), isolated from the whole gastrointestinal tract of indigenous chubs collected during spawning (April/May 2006) and post-spawning period (September 2006), seasonal or gender related differences of trace metals and proteins were determined. In both fractions, cytosol and heat-treated cytosol, metal levels decrease as follows: Zn > Fe > Cu > Mn > Cd and are significantly higher during the spawning period. Besides that, the level of heat-sensitive proteins (metalloenzymes) in cytosolic fractions is also significantly higher during the spawning period in both male and female specimens. Higher condition indices of chubs in the spawning period imply higher feeding activity, energy reserves and recent growth of indigenous chubs. Metallothionein levels, determined in the heat-treated cytosol, are comparable in gastrointestinal tract of feral chubs collected in both seasons and confine the background metallothionein levels, on average 3 mg g⁻¹ wet tissue. Chub spawning has been identified as a confounding factor, having an impact on cytosolic metal and protein levels, presumably due to enhanced food supply (higher condition indices) and fish spawning (higher gonadosomatic indices in some male specimens).     

Mussel beds on different types of structures support different macroinvertebrate assemblages

Abstract Artificial structures, such as seawalls, pilings and pontoons, are common features of urban estuaries. They replace natural structures or add to the amount of hard substratum in an area and provide habitats for many fish and invertebrates. Previous work has concentrated on fish or on the invertebrates that occupy the primary substratum of artificial structures. Mussels often grow on different types of structures (pontoons, pilings, seawalls and natural reefs) and provide a secondary substratum for other organisms to inhabit. Counting and identifying organisms associated with mussel beds is traditionally done to species level, which is very time‐consuming. To save time, organisms in this study were identified to coarse levels of taxonomic resolution (a mix of taxa, such as class, order, family and genus), which showed similar patterns to those when particularly speciose and abundant groups were identified to species. This study tests hypotheses that the distribution and abundance of mobile and sessile organisms that inhabit mussel beds will differ among natural and various types of artificial structures. When the associated assemblages of mussel beds from different types of structures and from different locations were examined, assemblages varied according to the type of structure they inhabited and its location. Assemblages associated with mussels on pontoons differed consistently from those on other types of structures. Patterns in the assemblages were also consistent through time. These data show that the types and amounts of artificial structures added to an environment can affect the types, distribution and abundances of organisms living in biogenic habitats.