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Emily Keeble David I. Whiteside Michael J. Benton 《Proceedings of the Geologists' Association. Geologists' Association》2018,129(2):99-119
Pant-y-ffynnon Quarry in South Wales yielded a rich cache of fossils in the early 1950s, including articulated specimens of new species (the small sauropodomorph dinosaur Pantydraco caducus and the crocodylomorph Terrestrisuchus gracilis), but no substantial study of the wider fauna of the Pant-y-ffynnon fissure systems has been published. Here, our overview of existing specimens, a few described but mostly undescribed, as well as freshly processed material, provides a comprehensive picture of the Pant-y-ffynnon palaeo-island of the Late Triassic. This was an island with a relatively impoverished fauna dominated by small clevosaurs (rhynchocephalians), including a new species, Clevosaurus cambrica, described here from a partially articulated specimen and isolated bones. The new species has a dental morphology that is intermediate between the Late Triassic Clevosaurus hudsoni, from Cromhall Quarry to the east, and the younger C. convallis from Pant Quarry to the west, suggesting adaptive radiation of clevosaurs in the palaeo-archipelago. The larger reptiles on the palaeo-island do not exceed 1.5?m in length, including a small carnivorous crocodylomorph, Terrestrisuchus, and a possible example of insular dwarfism in the basal dinosaur Pantydraco. 相似文献
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利用抑制性差减杂交技术(Suppression subtractive hybridization,SSH)对虾夷扇贝闭壳肌积累类胡萝卜素相关基因进行筛查和分析。以虾夷扇贝橘红色闭壳肌和白色闭壳肌cDNA构建正反向差减文库,结合454测序技术在正向差减文库中测序得到2 640条序列,拼接得到50个contigs(重叠群);反向差减文库中测序得到2 496条序列,拼接得到187个contigs。经过同源性比对分析,共获得150多个差异表达基因,从中选择3种清道夫受体SRB1、SRF2和SRCR作为候选基因进行研究,对其在虾夷扇贝各组织中的表达量水平进行检测,初步阐述了其在虾夷扇贝中的组织表达规律。根据结果推测在虾夷扇贝橘红色闭壳肌中,清道夫受体有可能是调节类胡萝卜素累积和转运的关键基因。本研究为虾夷扇贝闭壳肌类胡萝卜素累积相关通路的探索提供了初步研究的基础数据。 相似文献
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Though the larval development of bivalves has been extensively studied for commercial purposes,the dynamic development of larval muscle system remains largely unknown.In this study,we characterized the larval muscle system at different developmental stages(D-shaped veligers,umbo veligers and spats)in the bay scallop(Argopecten irradians)by phalloidin staining and under a confocal microscopy.The functional muscles are initially established at the early stage of veligers,which have four pairs of velar retractors and one anterior adductor.At the veliger stage,the velum and posterior retractor muscles are functionally important for velar contractility but undergo an irreversible shrink until they disappear at the end of the larval stage.During metamorphosis,three crucial modifications take place in the larval muscle system.The metamorphosis process involves the gradual degeneration of velum retractors,mantle margin development from an unfolded to a three-fold state,and remodeling of the adductor muscle system from dimyarian(two adductors)to monomyarian condition(one adductor)as in juveniles/adults.All retractor muscles are composed of striated muscle,but both anterior and posterior adductors have smooth and striated components.These findings highlight that the morphological changes at different stages are typical features of myogenesis in scallops.The present knowledge on the developmental dynamics of myogenesis in the bay scallop will not only improve our understanding of phenotypic diversity of larval myoanatomy in bivalves,but also provide useful information on the larval culture in hatcheries. 相似文献
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闭壳肌的疤痕部位（AMS）是闭壳肌和壳的固定点。它是一个重要的有机-无机界面和应力分布面。尽管有一些近期的研究进展,我们对AMS组成和结构的了解仍然是有限的。这里,我们研究比较了三种双壳类动物：厚壳贻贝、栉孔扇贝、菲律宾蛤仔的AMS。结果表明这三种动物的AMS明显不同。厚壳贻贝和栉孔扇贝在AMS的壳结构珍珠片层上部有一柱状层,该层在厚壳贻贝中的结构更有规律。菲律宾蛤仔缺乏此柱状层。原子力显微镜结果显示在三种软体动物中AMS的结构比珍珠层结构更光滑。傅立叶变换红外分析结果显示珍珠层和AMS层组成成分略有不同。聚丙烯酰胺凝胶电泳蛋白分离结果显示在厚壳贻贝界面柱状层存在一种约70 kDa的蛋白。对这种蛋白的进一步分析显示其还有较高摩尔比的Asx（Asp+Asn）,Glx（Glu+Gln）和Gly。AMS的特殊结构和组成对其稳定性、粘性以及在该应力分散部位的功能有重要作用。 相似文献
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Mickaël Dutertre Laurent Barillé Peter G. Beninger Philippe Rosa Yves Gruet 《Estuarine, Coastal and Shelf Science》2009
Spatial size variations of labial palps, gills and the adductor muscle of the invasive feral oyster, Crassostrea gigas, were studied along two gradients of suspended particulate matter (SPM) concentrations in the temperate macrotidal Bourgneuf Bay, (annual mean SPM concentration gradient of 21.0–154.0 mg l−1) and the adjacent Loire Estuary (annual mean SPM concentration gradient of 24.1–630.4 mg l−1) on the French Atlantic Coast. The gill-to-palp (G:P) ratios decreased with increasing turbidity, both in the bay and the estuary. Changes in G:P ratios were chiefly related to palp area variations, increasing gradually from low turbidity to very high-turbidity sites, while gill area showed no clear relationship with turbidity conditions. The G:P ratio, showing a significant relationship (r2 = 0.97) with SPM concentrations, is proposed as a pallial organ index of oyster acclimation to turbidity conditions. The area of the striated part of the adductor muscle was always greater than that of the smooth one, and adductor muscle area tended to decrease when SPM concentration increased. These observations show the morphological capacity of the oyster C. gigas to tolerate SPM concentrations above the feeding cessation thresholds previously determined experimentally. They also suggest that pallial organ size variations could help explain the success of recent feral oyster invasions in temperate turbid ecosystems. 相似文献
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