Experimental Oesophagostomum dentatum infection in the pig: Worm populations resulting from single infections with three doses of larvae

This report describes the effect of different dose levels of infection upon worm burdens and development and fecundity of the parasites. Three groups each of 40, 9-week-old, helminth naïve pigs were inoculated once with either 2000 (group A), 20,000 (group B), or 200,000 (group C) infective third stage larvae of Oesophagostomum dentatum. Subgroups of 5 pigs from each major group were killed 3, 6, 11, 14, 18, 25, 34 and 47 days post inoculation (p.i.) and the large intestinal worm burdens were determined. Faecal egg counts were determined at frequent intervals after day 13 p.i. There were no overt clinical signs of gastrointestinal helminthosis during the experiment. Faecal egg counts became positive in groups A and B at around day 19 p.i., whereas most pigs in the high dose group C did not have positive egg counts until day 27–33 p.i. and some pigs remained with zero egg counts until the end of the study. Throughout the experiment the worm populations in group C consisted mainly of immature larval stages, while those in groups A and B were predominantly adult stages after days 14–18. Adult worms from the low dose group A were significantly longer than those from group C. At high population densities, stunted development of worms and reduced fecundity among female worms were found. Furthermore, there was a tendency for the distribution of the worms within the intestine to be altered with increasing population size.     

东海具齿原甲藻的扫描电子显微结构

在光学显微镜分析鉴定的基础上,通过高分辨率的扫描电子显微镜,对东海赤潮原甲藻标本和美国国家海洋藻种中心(CCMP)的具齿原甲藻(Prorocentrum dentatum)藻株(CCMPl517)的细胞表面结构进行观察和比较,认为两者为同一种类．在分析大量文献资料的基础上,可以认为发生在我国东海水域的赤潮原甲藻种类是具齿原甲藻(Prorocentrum dentatum),而非新种．     

POTENTIAL UTILITY OF MITOCHONDRIAL CYTOCHROME B AND ITS MRNA EDITING IN RESOLVING CLOSELY RELATED DINOFLAGELLATES: A CASE STUDY OF PROROCENTRUM (DINOPHYCEAE)1

Difficulties often occur in separating closely related dinoflagellate species. In this study, the potential utility of mitochondrial cytochrome b (cob) gene sequence and mRNA editing characteristics was assessed using Prorocentrum Ehrenberg as a model. The cob sequences and the patterns of their mRNA editing were analyzed for several Prorocentrum taxa. Results revealed little difference in cob sequence and mRNA editing characteristics between geographic populations of P. minimum (Pavillard) Schiller, while a notable difference was detected between different species (P. minimum and P. micans Ehrenberg). Furthermore, these P. minimum populations consistently formed a tight cluster on phylogenetic trees inferred from cob sequences as well as mRNA editing characteristics, whereas different Prorocentrum species were well separated, with a genetic distance of 0.0042±0.0024 for the former and 0.0141±0.0012 for the latter (P<0.01; two‐tailed t‐test). When the analysis was applied to the case of P. donghaiense Lu et Goebel and CCMP1517 strain of P. dentatum Stein, no differences were detected between these two taxa with respect to cob mRNA editing pattern and only small differences equivalent to those between P. minimum populations were detected in terms of cob sequence. On the cob sequence‐ and editing‐based phylogenetic trees, P. donghaiense and P. dentatum CCMP1517 consistently clustered together at a position sister to P. minimum. The results suggest that cob, combined with its mRNA editing, can potentially be a useful delineator of Prorocentrum species, and that P. donghaiense and P. dentatum CCMP1517 are most likely the same species and both are closely related to P. minimum.     

我国东海赤潮原甲藻应属哪种？

阐述并讨论了中国东海长江口外经常发生的原甲藻赤潮原因种的种类认知问题．论述了自从Stein提出具齿原甲藻(Prorocendrum dentatum Stein)新种后迄今中外专家报告该种的描述及分布,并对比了具齿原甲藻与长江口的原甲藻的异同．研究证实我国东海的原甲藻与具齿原甲藻有较大的差别,主要表现在体积大小、藻体末端形态以及藻体前端突起的大小和形态等方面．本文汇集了国内外对具齿原甲藻与我国原甲藻的研究成果,对比认为。我国长江口外经常发生赤潮的原甲藻为东海原甲藻(Prorocendrum donghaiense Lu)．文中还讨论了由陆斗定发表的东海原甲藻需要补充修正的观点．在过去的数年中,我国东海长江口海域频繁爆发大面积的原甲藻赤潮,但对于赤潮原因种原甲藻(Prorocentrum)的定种问题存在两种不同的观点,一种观点认为本种是具齿原甲藻,另一种观点认为是东海原甲藻．为了阐明此种原甲藻的命名问题,于2002年11月在深圳召开了题为“我国东海赤潮原因种原甲藻分类学国际研讨会”．认为是P．dentatum的依据是长期以来国际上通常把类似我国东海的原甲藻定为P．dentatum,其根据是它的前端有突起等．而持不同观点的专家认为我国东海的这种原甲藻在细胞长度上与Stein描述的原P．dentatum差异很大,并且除少数样品末端尖伸外,大多数细胞末端是钝圆的．专家们还认为在日本、韩国等亚洲海域分布的被报告为P．dentatum的原甲藻与我国东海的此种原甲藻为同一种．综观各种观点,作者认为东海本种原甲藻应为东海原甲藻.     

The Fine Structure of Saprodinium dentatum Lauterborn, 1908 as a Representative of the Odontostomatida (Ciliophora)

The fine structure of the sapropelic ciliate Saprodinium dentatum is described based on phase-contrast microscopy, silver-staining techniques, cryo-fracture scanning electron microscopy, and thin sections. The study concentrates on a detailed analysis of the somatic cortex and the oral ciliature of this highly asymmetric, laterally compressed ciliate. The cell shape is dominated by a number of site-specific spines and the curving course of 10 somatic kineties (SK 1–10). The SK, composed of dikinetids, show an intrakinety differentiation that seems characteristic for other odontostomes as well. The anterior segment of the SK is mostly ciliated, followed by a non-ciliated segment in which the kinetosomes lack all typical fiber systems. Except for SK 4–6, the posterior segment is ciliated again, forming the spine kinetics associated with particular caudal spines. The anterior segment of SK 3 through SK 7 form the frontal band, which together with the two frontal kineties constitutes the main locomotory organelle for a ciliate that creeps on the substratum. A short kinety with inverse polarity, not seen in earlier light microscopical studies, was observed near the oral spine. We made particular effort to find a logical explanation for the observed association of the SK with the various caudal spines. The oral ciliature consists of nine adoral organelles located in a tripartite oral cavity. The absence of a paroral ciliature together with the position of the cytostome anterior to the adoral organelles may be the result of rotational movement of the oral apparatus during the evolution of these bizarre ciliates. Results are discussed with special reference to the phylogenetic relationship of the Odontostomatida to the Heterotrichida and no conclusive answer was found in this first electron microscopical study of an odontostomatid ciliate.     

具齿原甲藻的生态特征及赤潮成因浅析

在东海的长江口和舟山海域,2000-2002年连续3年的5月发生罕见的大规模赤潮,赤潮生物为具齿原甲藻,为了解该种的生态特征及赤潮频发原因,本文分析近赤潮应急监测资料及野外生态调查资料,结果表明,该种适温,适盐范围分别为15-25℃和14-32,最适温度,盐度分别为18-22℃和22-31,该种运动能力较强,在海流交汇的紊乱水体中具有强适应能力,具有昼夜垂直移动特性,水温,硝酸盐含量,海流及上升流,磷限制环境下的种间竞争优势对诱发和维持赤潮具有重要作用.     

Population dynamics of the parasitic stages of Oesophagostomum dentatum in pigs in single and trickle infections

A mathematical model was developed to describe the dynamics of the parasitic stages of Oesophagostomum dentatam in pigs. An immigration-death model with constant establishment, development and death rates was fitted to L3, L4 and adult worm burdens observed in a single-infection experiment. Female worm length was modelled by a function of worm age and total worm burden, while worm egg production (eggs per gram faeces per female worm) was modelled by a function of worm age and worm length. The model was then used to predict worm burdens observed in a trickle-infection experiment. The predicted worm burdens were much higher than those observed, suggesting that worm death rates were higher during the trickle infection. After increusing worm death rates to fit the observed worm burdens, female worm lengths and egg production in the trickle infection were predicted. At the medium- and high-dose rates, predicted worm lengths and, thus, egg preduction were lower than observed, while at the low-dose rate predicted egg production was too high. It appeared that in the trickle infections, total worm burden had less influence on observed female worm length and egg production than in the single infections. The results suggest that the demography of O. dentatum in pigs differs between single and trickle infections.     

中国种子植物新资料

【目的】青藏高原因其特殊的地理位置、丰富的植被类型及复杂多变的气候条件,使其拥有独特而宝贵的植物资源。明确该地区植物本底资料及地理分布对本区域植物区系研究有着十分重要的意义。【方法和结果】文章以西藏自治区定日县嘎玛沟区域高山植物多样性及区系调查为基础,发现3个中国新记录种,即盔角马先蒿(Pedicularis cornigera T.Yamaz.)、细齿滇藁本[Hymenidium dentatum(DC.) Pimenov&Kljuykov]、噶穆兔耳草(Lagotis kunawurensis Rupr.)。【结论】文章对以上3个中国新记录种进行报道,对于研究该地区植物组成具有一定参考价值,同时为青藏高原植物多样性保护及植物系统分类补充新资料。