记真盔甲鱼类两新属——兼论真盔甲鱼类系统发育关系

本文记述了早泥盆世真盔甲鱼类两新属:憨鱼属(Nochelaspis)和翼角鱼属(Pterogonaspis).真盔甲鱼类是盔甲鱼类的一个单系类群,现有七属十二种,文中运用分支系统学原理对其系统发育关系进行了初步探讨.     

云南早泥盆世一流线型盔甲鱼及其分类学与古生态学意义(英文)

记述了云南昭通早泥盆世布拉格期坡松冲组华南鱼目一新属、新种——剑裂甲鱼(Rhegmaspis xiphoidea gen.et sp.nov.)。新属的主要特征是:具有鱼雷形头甲,细长吻突,眶孔位于头甲腹侧位,鳃穴向头甲腹面弯曲,角、内角和腹环丢失。鉴于以上特征,新属被归到了包括鸭吻鱼和乌蒙山鱼在内的鸭吻鱼科。根据新材料提供的信息,修订了鸭吻鱼科,包括鸭吻鱼和乌蒙山鱼的鳃穴、腹环、角、内角等特征。裂甲鱼属是该地区发现的第一个具有流线形体型的盔甲鱼类,指示了该地区一些盔甲鱼类可能开始了一种营上底栖的生活方式,具有更加主动的取食行为。新属的发现不仅丰富了该地区华南鱼目的多样性,而且提供了盔甲鱼类在早泥盆世布拉格期通过占据新的生态位而发生的最后一次辐射演化的证据。     

盔甲鱼亚纲(无颌类)的系统发育关系

基于对53个形态学特征的讨论,首次开展了无颌类儒甲鱼亚纲的简约性分析,获得了3 个最简约的分支图,其步长为126,一致性指数为0．508,保留指数为0．801。在此基础上,修订了盔甲鱼亚纲的分类。研究结果表明,志留纪兰多维列世至温洛克世的汉阳鱼类、修水鱼类和大庸鱼类属于盔甲鱼亚纲的基干类群。在其余盔甲鱼类中,识别出3个大的单系类群, 分别是真盔甲鱼目、多鳃鱼目和华南鱼目。在盔甲鱼亚纲中,头甲背窗的起源至少发生了两次,一次在多鳃鱼目支系中,另一次在华南鱼目支系中。基于背窗特征而建立的大窗鱼类并不是一个单系类群。盔甲鱼类的年代分布指示该类群的两次辐射演化,分别是兰多维列世特列奇期基干盔甲鱼类和真盔甲鱼目的辐射演化,和早泥盆世洛霍考夫期多鳃鱼目和华南鱼目的辐射演化。     

记一新的无颌类化石兼论多鳃鱼类的分类地位

本文记述了云南宜良早泥盆世一新的无颌类化石,高棘四营鱼,新属、新种 (Siyingiu altuspinosa gen.et sp.nov)。在讨论中主要涉及鼻垂体凹的构造和多鳃鱼类的分类地位。笔者认为,多鳃鱼类和盔甲鱼类的鼻垂体孔位于鼻垂体凹的软骨成分中,它没有吸水的功能,只具感觉的功能。多鳃鱼目不应置于鳍甲鱼纲,而应放在头甲鱼纲的盔甲鱼亚纲中。在盔甲鱼亚纲中,南盘鱼不是接近于盔甲鱼目而是接近于多鳃鱼目。     

关于盔甲鱼类若干问题的讨论

对盔甲鱼类研究中存在的若干问题进行了讨论:1)盔甲鱼类侧线系统的感觉管既不存在通向体表的上升管,迄今亦未发现其具通向体表的任何通道,所谓的感觉管裂隙,实乃假像。因此,其侧线如何与外在水体沟通和如何发挥功能仍是令人困惑的问题;2)网状安吉鱼Anjiaspis reticularis所谓的网状侧线系统,实系对皮下脉管丛(subaponeurotic vascular plexus)的误判,其真实的侧线系统目前仍不详;3)耿氏鸭吻鱼Gantarostrataspis gengi的侧线系统与华南鱼类和多鳃鱼类可作一对一对比,只是其唯一的一对中横管位置超前,未见于其他已知盔甲鱼类;4)巢湖汉阳鱼Hanyangaspis chaohuensis中所谓"腹片"和其上的侧线感觉管"腹侧沟"实乃不完整头甲背面和其上的裂隙,盔甲鱼类的腹片上迄今尚未发现感觉管的存在;5)盔甲鱼类是否存在松果孔长期存在争议,现查明是由于覆盖松果区的骨甲薄而易损毁,以致常现出松果孔存在的假象,真实的松果孔只存在于极少数种类。正在编写中国古脊椎动物志第一卷第一册无颌类盔甲鱼类这部分内容的过程中,我们对盔甲鱼类近50年的研究成果进行了系统梳理,对大量标本作了重新观察、照相和重绘复原图等基础性工作。在这个过程中,我们获得了一些新的认识,同时也发现不少需要商榷的问题。这些问题无法在志书中三言两语讲清楚,十分有必要专文加以讨论。为此,本文尝试从以下5例先行论述,作为对志书工作的一个有益补充。1盔甲鱼类侧线系统如何与外界沟通的困惑     

云南文山早泥盆世盔甲鱼类的新发现

描述了采自云南东南部文山地区下泥盆统坡松冲组下部的无颌类化石,建立了盔甲鱼类的一新属、新种──纸厂文山鱼(Ｗｅｎｓｈａｍｐｉｓ ｚｈｉｃｈａｎｇｓｉｓ ｇｅｎ．ｅｔ ｓｐ．ｎｏｖ．),同时修订了两个盔甲鱼类的旧属、旧种──长吻三歧鱼(Ｓａｎｑｉａｐｉｓ ｒｏｓｔｒａｔａ)及长角大窗鱼(Ｍａｃｒｏｔｈｙｒａｓｐｉｓｌｏｎｇｉｃｏｒｎｉｓ)。迄今为止,长吻三歧鱼仅在四川江油雁门坝的平驿铺组中部发现并记述过,长角大窗鱼也仅有一件采自云南广南坡松冲组中的正型标本,而纸厂文山鱼为滇东南文山地区首次记述的多鳃鱼类新属种,它与滇东北昭通地区下泥盆统坡松冲组中的让氏昭通鱼(Ｚｈａｏ－ｔｏｎｇａｓｉｓ ｊａｎｖｉｅｒｉ)最为相似。此次这三个盔甲鱼类属种在滇东南文山地区的发现,为该区下泥盆统的横向对比提供了重要的古鱼类学方面的证据。     

云南曲靖下泥盆统盔甲鱼类(无颌类)的新发现（英文）

描述了云南曲靖早泥盆世西山村组盔甲鱼类(无颌类)的新发现,包括一新属、新种——惠清驼背鱼(Altigibbaspis huiqingae gen.et sp.nov.),一件属种未定的多鳃鱼科标本,以及张氏真盔甲鱼(Eugaleaspis changi)和小眼南盘鱼(Nanpanaspis microculus)的新材料。驼背鱼在很多方面与多鳃鱼都非常相似,但头甲背面具一特征性的驼背状隆起,其上有一刀刃状的中背脊。中背脊和中背棘在盔甲鱼类里的形态分异度表明,它们除了能够提供游泳方向稳定性外,可能还衍生出了一些附加的功能,例如直立高耸的中背棘能使盔甲鱼在捕食者眼里具有了恐吓性,刀刃状的中背脊可能也起到一些防御的作用。南盘鱼头甲侧缘具有两对非常奇特的侧向延伸的突起;通过对这两对侧突同源性的比较,讨论了南盘鱼的潜在系统分类位置。鉴于南盘鱼奇特的形态,以及它在华南鱼目中相对较早的出现时代,建议暂时把南盘鱼放到一个单属科南盘鱼科,代表了华南鱼目早期分出来的一个支系。     

滇东北昭通附近早泥盆世脊椎动物化石新知

本文记述了发现于云南昭通箐门沟箐门水库附近的几件早期脊椎动物化石,其中包括盔甲鱼类一新种,层位是下泥盆统坡松冲组。新种云南龙门山鱼（Lungmenshanaspisyunnanensissp.nov）与属型种江油龙门山鱼在纹饰上存在明显等异。其头甲侧凹应为自然边缘,龙门山鱼侧背孔并不存在。本文描述的骨鳞鱼类为目前所知层位最低的骨鳞鱼类化石,其额筛甲前端向下强烈弯曲,具分离的前上颌骨,具有杨氏鱼的一些特征。其眼眶凹非常大且深,下颌垂直凹线的位置十分靠前,k／m值在已知的骨鳞鱼目种类中为最大。昭通三歧鱼（SanqiaspiszhaotongensisLiu）新材料补充了正型标本在感觉管系统保存上的不足。文中对有关的生物地层问题也作了讨论。     

鲤科鱼类咽喉齿的剥取与计数

鲤科鱼类是鱼类中最大的科,因而也最为常见.在我国淡水鱼类中,鲤科分为9亚科119属700余种,占淡水鱼类的半数以上(56％左右).由于鲤科鱼口腔诸骨上不生牙齿,而在喉部的咽骨(第五对鳃弓演变而成)上长有牙齿,因而称为咽喉齿或下咽齿.咽喉齿的排列行数和各行齿数(齿式)以及齿的大小、形状,为鲤科鱼分类的重要依据之一,因而剥取咽喉齿及其计数,是研究鲤科鱼的一项重要基本功. 根据大小不同类型的鱼体,采用眼科镊子、普通镊子甚至骨钳,先微微挑起鳃盖的后缘,合拢镊子插人鳃孔,以鱼头宽度的一半为插入深度,自背方向腹方沿鳃     

滇东北昭通早泥盆世盔甲鱼类一新属种

本文记述了在滇东北昭通早泥盆世Pragian期坡松冲组中发现的盔甲鱼类一新属种,让氏昭通鱼（Zhaotongaspisjanvierigen．etsp．nov．）,该属至少具有31对鳃穴,这是迄今为止记述过无颌类中的最高数目。基于昭通标本,建立了盔甲鱼类一新科,昭通鱼科（Zhao－tongaspidae）,该科隶属于多鳃鱼目。箭甲鱼属（Antiquisagittaspis）是新科的可能成员。文章认为,昭通鱼科与都匀鱼科（Duyunaspidae）有较近的亲缘关系。     

Causality, randomness, intelligibility, and the epistemology of the cell

Because the basic unit of biology is the cell, biological knowledge is rooted in the epistemology of the cell, and because life is the salient characteristic of the cell, its epistemology must be centered on its livingness, not its constituent components. The organization and regulation of these components in the pursuit of life constitute the fundamental nature of the cell. Thus, regulation sits at the heart of biological knowledge of the cell and the extraordinary complexity of this regulation conditions the kind of knowledge that can be obtained, in particular, the representation and intelligibility of that knowledge. This paper is essentially split into two parts. The first part discusses the inadequacy of everyday intelligibility and intuition in science and the consequent need for scientific theories to be expressed mathematically without appeal to commonsense categories of understanding, such as causality. Having set the backdrop, the second part addresses biological knowledge. It briefly reviews modern scientific epistemology from a general perspective and then turns to the epistemology of the cell. In analogy with a multi-faceted factory, the cell utilizes a highly parallel distributed control system to maintain its organization and regulate its dynamical operation in the face of both internal and external changes. Hence, scientific knowledge is constituted by the mathematics of stochastic dynamical systems, which model the overall relational structure of the cell and how these structures evolve over time, stochasticity being a consequence of the need to ignore a large number of factors while modeling relatively few in an extremely complex environment.     

The parasitic chytrid, Zygorhizidium, facilitates the growth of the cladoceran zooplankter, Daphnia, in cultures of the inedible alga, Asterionella

In food-web studies, parasites are often ignored owing to their insignificant biomass. We provide evidence that parasites may affect trophic transfer in aquatic food webs. Many phytoplankton species are susceptible to parasitic fungi (chytrids). Chytrid infections of diatoms in lakes may reach epidemic proportions during diatom spring blooms, so that numerous free-swimming fungal zoospores (2-3 microm in diameter) are produced. Analysis shows that these zoospores are rich in polyunsaturated fatty acids and sterols (particularly cholesterol), which indicates that they provide excellent food for zooplankters such as Daphnia. In life-table experiments using the large diatom Asterionella formosa as food, Daphnia growth increased significantly in treatments where a parasite was present. By grazing on the zoospores, Daphnia acquired important supplementary nutrients and were able to grow. When large inedible algae are infected by parasites, nutrients within the algal cells are consumed by these chytrids, some of which, in turn, are grazed by Daphnia. Thus, chytrids transfer energy and nutrients from their hosts to zooplankton. This study suggests that parasitic fungi alter trophic relationships in freshwater ecosystems and may be the important components in shaping the community and the food-web dynamics of lakes.     

Expression, localization, structural, and functional characterization of pFGE, the paralog of the Calpha-formylglycine-generating enzyme

pFGE is the paralog of the formylglycine-generating enzyme (FGE), which catalyzes the oxidation of a specific cysteine to Calpha-formylglycine, the catalytic residue in the active site of sulfatases. The enzymatic activity of sulfatases depends on this posttranslational modification, and the genetic defect of FGE causes multiple sulfatase deficiency. The structural and functional properties of pFGE were analyzed. The comparison with FGE demonstrates that both share a tissue-specific expression pattern and the localization in the lumen of the endoplasmic reticulum. Both are retained in the endoplasmic reticulum by a saturable mechanism. Limited proteolytic cleavage at similar sites indicates that both also share a similar three-dimensional structure. pFGE, however, is lacking the formylglycine-generating activity of FGE. Although overexpression of FGE stimulates the generation of catalytically active sulfatases, overexpression of pFGE has an inhibitory effect. In vitro pFGE interacts with sulfatase-derived peptides but not with FGE. The inhibitory effect of pFGE on the generation of active sulfatases may therefore be caused by a competition of pFGE and FGE for newly synthesized sulfatase polypeptides.     

Biosynthesis of grandlure,the pheromone of the boll weevil,Anthonomus grandis,from acetate,mevalonate, and glucose

The steam-distilled faeces of adult male boll weevils, Anthonomus grandis, that had been injected with acetate-1¹⁴C, acetate-2¹⁴C, mevalonic acid-2¹⁴C, or glucose¹⁴C(U) showed by column and gas chromatography that approximately 0·02 per cent of the administered radioactivity was incorporated into the volatile fraction. Also, 4 components of the pheromone comprised 57 to 80 per cent of the radioactivity of the volatiles but only 39 per cent of the total content of volatiles. Thus, evidence was obtained for de novo synthesis of the components. Although the boll weevil is essentially an obligate insect of cotton, this insect does not appear to require any specific component in cotton for biosynthesis of the pheromone.     

Checklist of the species of the aseptate gregarine families Aikinetocystidae,Diplocystidae, Allantocystidae,Schaudinnellidae, Ganymedidae,and Enterocystidae

The genera and species in six families of the eugregarine suborder Aseptatorina Chakravarty, 1960, are reviewed and the presently accepted ones are listed: Aikinetocystidae Bhatia, 1930 (two genera and two species); Diplocystidae Bhatia, 1930 (one genus and eight species); Allantocystidae tocystidae Bhatia, 1930 (one genus and one species); Schaudinnellidae Poche, 1913 (one genus and one species); Ganymedidae Huxley, 1910 (one genus and one species); and Enterocystidae Codreanu, 1940 (one genus and eight species). A list of 22 synonyms and lapsi calami is also given. Species which might be of value in the biological control of disease vectors are indicated.     

Quantitation of the involvement of the recA, recB, recC, recF, recJ, recN, lexA, radA, radB, uvrD, and umuC genes in the repair of X-ray-induced DNA double-strand breaks in Escherichia coli

Isogenic Escherichia coli strains carrying single DNA-repair mutations were compared for their capacity for (i) the repair of X-ray-induced DNA double-strand breaks (DSB) as measured using neutral sucrose gradients; (ii) medium-dependent resistance, i.e., a recA-dependent X-ray survival phenomenon that correlates closely with the capacity for repairing DSB; and (iii) the growth medium-dependent, recA-dependent repair of X-ray-induced DNA single-strand breaks (SSB) as measured using alkaline sucrose gradients (about 80% of these SSB are actually parts of DSB). These three capacities were measured to quantitate more accurately the involvement of the various genes in the repair of DSB over a wide dose range. The mutations tested were grouped into five classes according to their effect on the repair of X-ray-induced DSB: (I) the recA, recB, recC, and lexA mutants were completely deficient; (II) the radB and recN mutants were about 90% deficient; (III) the recF and recJ mutants were about 70% deficient; (IV) the radA and uvrD mutants were about 30% deficient; and (V) the umuC mutant resembled the wild-type strains in its capacity for the repair of DSB.