富铝酸水对大西洋鲑卵和仔鱼的毒性影响

测定了培养于不同水质中的大西洋鲑卵和仔鱼在发育过程中的主要离子含量,并比较了它们的死亡率和生长率。在320μg/l无机铝溶液中,当pH值为6.0时,仔鱼死亡率增加。pH为5.5时晚期胚胎和仔鱼对氯和钠离子的摄取明显减少,pH为6.5时,由于Al(OH)_3产生沉淀,因而未见到对卵和仔鱼的离子摄取或排出有任何影响。对钾、钙、镁的影响不明显。加入海水对铝的毒性没有缓解作用。本文还讨论了铝对离子调节的作用方式。     

白点鲑胚胎与仔鱼发育

通过Bouin's液、5%的福尔马林、透明液固定和活体解剖观察等4种不同方法,对白点鲑(Salvelinus leucomaenis)胚胎和仔鱼发育进行了系统观察,描述了早期发育过程。白点鲑受精卵为端黄卵,沉性,橙黄色,呈圆球形。在水温3.40～8.89℃,受精卵历时1 944 h,经历6个阶段的胚胎发育破膜孵出仔鱼;初孵仔鱼全长(17.89±0.32)mm,破膜后73 d各鳍条发育完全,并出现"幼鲑斑",破膜后350d鱼体外部形态与成鱼基本相同。将白点鲑与几种鱼类进行了对比,并且探讨了其胚胎发育特点。经比较4种不同观察方法,Bouin's液固定后剥离卵膜观察是研究白点鲑等卵膜较厚鱼类的理想方法。     

亚东鲑消化系统的形态学和组织学观察

亚东鲑消化系统包括消化道和消化腺。消化道分为明显的食道、胃和肠等。食道粘膜为复层上皮,其中含有杯状细胞和味蕾,胃、肠粘膜为单层柱状上皮,其中散布较多的杯状细胞。消化腺包括肝脏和胰腺,肝小叶分界明显,胰腺外分泌部由腺泡组成,内分泌部即胰岛分散存在于外分泌部之间。     

异育银鲫源杀鲑气单胞菌杀鲑亚种的分离鉴定

【目的】分离鉴定江苏省扬州市养殖场异育银鲫患病病原。【方法】采用常规的理化特性和分子生物学的方法,对从濒死异育银鲫肝脏处分离到的菌株YZ-1进行表型生物学、分子生物学及药敏试验的系统研究。【结果】该菌株16S r RNA基因(序列长度1 446 bp,Gen Bank登录号为JX164202)与其它杀鲑气单胞菌16S r RNA基因一致性在99%-100%之间,构建发育树确定该菌株为杀鲑气单胞菌杀鲑亚种(Aeromonas salmonicida subsp.salmonicida)。人工回感可导致异育银鲫死亡。药敏试验结果显示:对头孢呋辛、复方新诺明、恩诺沙星等23种抗生素敏感;对阿米卡星、四环素、大观霉素、头孢拉定等11种抗生素中度敏感;对青霉素G、链霉素、庆大霉素、氟苯尼考、万古霉素等10种抗生素耐药。【结论】研究结果证实引起异育银鲫死亡的病原为杀鲑气单胞菌杀鲑亚种。     

基于形态学差异探讨秦岭细鳞鲑亚种有效性问题

秦岭细鳞鲑(Brachymystax lenok tsinlingensis Li)的亚种分类地位自命名以来一直饱受争议。研究运用单因素方差分析、主成分分析、判别分析、聚类分析及差异系数检验法, 对秦岭细鳞鲑和黑龙江流域的尖吻细鳞鲑(B. lenok lenok)和钝吻细鳞鲑(B. tumensis)的5项可数性状和34项标准化后的比例性状进行统计分析。单因素方差分析结果表明, 尖吻细鳞鲑、钝吻细鳞鲑和秦岭细鳞鲑在32项比例性状和5项可数性状上存在极显著差异(P<0.01); 主成分分析结果显示, 贡献率较大的前3个主成分的累计贡献率为92.779%; 以逐步判别分析方法选用14个判别效果较好的比例性状构建了3个细鳞鲑类群的判别函数, 综合判别率为99.4%。基于欧式距离矩阵法构建的形态学聚类图显示, 秦岭细鳞鲑和尖吻细鳞鲑距离较近, 而与钝吻细鳞鲑距离较远。据Mayr 75%亚种识别和划分规则, 34项比例性状和5项可数性状中, 尖吻细鳞鲑和秦岭细鳞鲑第一鳃弓外鳃耙数目的差异系数大于1.28, 而钝吻细鳞鲑和秦岭细鳞鲑有31项比例性状和2项可数性状的差异系数高于1.28。据分析结果, 结合秦岭细鳞鲑地理隔离的事实及其与尖吻细鳞鲑和钝吻细鳞鲑的形态差异, 推断秦岭细鳞鲑与黑龙江流域内的尖吻细鳞鲑的形态差异程度至少已达亚种水平。     

长江上游网箱养殖圆口铜鱼杀鲑气单胞菌杀鲑亚种的分离与鉴定

研究首次报道了圆口铜鱼(Coreius guichenoti)疥疮病, 从患病圆口铜鱼的肝脏中分离到优势菌株YTL1, 并运用形态学观察、生理生化检测、16S rRNA和6个管家基因的系统发育分析等对分离菌株进行鉴定。基于以上实验结果, YTL1被最终鉴定为杀鲑气单胞菌杀鲑亚种(Aeromonas salmonicida subsp. salmonicida)。通过标准Kirby-Bauer纸片扩散法进行抗菌药物敏感性试验, 筛选治疗该暴发病的有效药物, 结果显示YTL1对氟苯尼考, 诺氟沙星和氨苄青霉素等13种抗生素敏感, 对6种抗生素如杆菌肽, 链霉素和卡那霉素有耐药性, 对红霉素具有中等敏感性。因此, 氟苯尼考被建议用来伴饵投喂, 并取得了较好的疾病控制效果。草鱼幼鱼(Ctenopharyngodon idella)和斑马鱼(Danio rerio)的人工感染试验结果显示, 经腹腔注射7.6×106—7.6×108 CFU/mL的YTL1菌液后, 感染鱼的症状与患病圆口铜鱼症状相似。研究证明基于6个管家基因的多序列位点分型是鉴定杀鲑气单胞菌至亚种水平的一种有效方法, 杀鲑气单胞菌是圆口铜鱼人工养殖的最大威胁之一, 并发现鲤科鱼类, 如草鱼和斑马鱼均是杀鲑气单胞菌杀鲑亚种的易感宿主。     

基于线粒体控制区和微卫星标记探讨秦岭细鳞鲑物种有效性

文章基于线粒体控制区基因序列和微卫星标记比较秦岭细鳞鲑(Brachymystax tsinlingensis Li)、黑龙江流域的尖吻细鳞鲑(Brachymystax lenok Pallas)和钝吻细鳞鲑(Brachymystax tumensis Mori)的分子遗传差异,为澄清其分类地位争议提供分子证据。结果表明:(1)扩增217个样本的mtDNA D-loop区序列,共获得45个单倍型,类群间无共享单倍型;基于单倍型构建的系统进化树显示三个细鳞鲑类群呈独立的支系;(2)基于14个呈多态性位点的遗传分化结果表明,秦岭细鳞鲑与尖吻或钝吻细鳞鲑之间的遗传距离均大于尖吻细鳞鲑和钝吻细鳞鲑之间的遗传距离;(3)基于线粒体D-loop和多态性微卫星位点计算出的遗传分化系数(F_ST)都远高于0.25表明三个类群间的遗传分化程度极高。这些结果表明,秦岭细鳞鲑与黑龙江流域细鳞鲑之间遗传分化程度高,结合前期发现秦岭细鳞鲑与黑龙江细鳞鲑类群有明显形态分化的研究结果及它们之间地理隔离已久的现状,研究初步判定秦岭细鳞鲑为独立物种,并建议以Brachymystax tsinlinge...     

秦岭细鳞鲑(Brachymystax tsinlingensis)与细鳞鲑(Brachymystax lenok)当年幼鱼几何形态学特征的比较

秦岭细鳞鲑(Brachymystaxtsinlingensis)和细鳞鲑(Brachymystax lenok)为近缘种,均为国家Ⅱ级重点保护野生动物,对二者当年幼鱼几何形态学特征的比较可为物种鉴定与保护、增殖放流等提供重要依据。为探究当年幼鱼的形态差异,运用Tps软件建立薄板样条模型,比较了24项相对几何形态学特征的差异并进行了主成分分析。结果表明：二者的整体结构框架背景网格在头部、背部、尾部和腹部均呈现不同程度的弯曲,细鳞鲑的头部稍尖;秦岭细鳞鲑的13项相对几何形态学特征与细鳞鲑存在显著差异(P<0.05),如背鳍基部长度(C4/C1)、臀鳍基部长度(C13/C1)、眼径(C20/C1)、头高(C25/C1)大于细鳞鲑(P<0.05),而胸鳍基部至吻端的相对距离(C16/C1)小于细鳞鲑(P<0.05)。主成分分析显示,秦岭细鳞鲑与细鳞鲑在PC1和PC2水平上仅个别样本出现重叠分布,两物种的样本相对集中。总之,秦岭细鳞鲑与细鳞鲑当年幼鱼的几何形态学特征具有显著种间差异,特别是头部和尾部特征。     

黑龙江流域两种细鳞鲑的形态学比较及其分类地位初探

对比研究了分布于我国黑龙江流域具钝吻和尖吻两种形态特征的细鳞鲑,其主要形态学性状的显著差异达到种间分化水平.细鳞鲑属Brachymystax在中国应有两个种,分别为图们江细鳞鲑B.tumensis(具钝吻特征)和细鳞鲑B.lenok(具尖吻特征).     

Identification key for European strand-forming house-rot fungi

An identification key for 20 common strand-forming indoor wood decay fungi is given. The key is based on observations of material from affected buildings and on wood samples that have been incubated in the laboratory. The key is with macro- and microscopic photographs.     

Semicircular canal system in early primates

Mammals with more rapid and agile locomotion have larger semicircular canals relative to body mass than species that move more slowly. Measurements of semicircular canals in extant mammals with known locomotor behaviours can provide a basis for testing hypotheses about locomotion in fossil primates that is independent of postcranial remains, and a means of reconstructing locomotor behaviour in species known only from cranial material. Semicircular canal radii were measured using ultra high resolution X-ray CT data for 9 stem primates (“plesiadapiforms”; n = 11), 7 adapoids (n = 12), 4 omomyoids (n = 5), and the possible omomyoid Rooneyia viejaensis (n = 1). These were compared with a modern sample (210 species including 91 primates) with known locomotor behaviours. The predicted locomotor agilities for extinct primates generally follow expectations based on known postcrania for those taxa. “Plesiadapiforms” and adapids have relatively small semicircular canals, suggesting they practiced less agile locomotion than other fossil primates in the sample, which is consistent with reconstructions of them as less specialized for leaping. The derived notharctid adapoids (excluding Cantius) and all omomyoids sampled have relatively larger semicircular canals, suggesting that they were more agile, with Microchoerus in particular being reconstructed as having had very jerky locomotion with relatively high magnitude accelerations of the head. Rooneyia viejaensis is reconstructed as having been similarly agile to omomyids and derived notharctid adapoids, which suggests that when postcranial material is found for this species it will exhibit features for some leaping behaviour, or for a locomotor mode requiring a similar degree of agility.     

Analysis of the molecular cascade responsible for mesodermal limb chondrogenesis: Sox genes and BMP signaling

Here, we have studied how Sox genes and BMP signaling are functionally coupled during limb chondrogenesis. Using the experimental model of TGFbeta1-induced interdigital digits, we dissect the sequence of morphological and molecular events during in vivo chondrogenesis. Our results show that Sox8 and Sox9 are the most precocious markers of limb cartilage, and their induction is independent and precedes the activation of BMP signaling. Sox10 appears also to cooperate with Sox9 and Sox8 in the establishment of the digit cartilages. In addition, we show that experimental induction of Sox gene expression in the interdigital mesoderm is accompanied by loss of the apoptotic response to exogenous BMPs. L-Sox5 and Sox6 are respectively induced coincident and after the expression of Bmpr1b in the prechondrogenic aggregate, and their activation correlates with the induction of Type II Collagen and Aggrecan genes in the differentiating cartilages. The expression of Bmpr1b precedes the appearance of morphological changes in the prechondrogenic aggregate and establishes a landmark from which the maintenance of the expression of all Sox genes and the progress of cartilage differentiation becomes dependent on BMPs. Moreover, we show that Ventroptin precedes Noggin in the modulation of BMP activity in the developing cartilages. In summary, our findings suggest that Sox8, Sox9, and Sox10 have a cooperative function conferring chondrogenic competence to limb mesoderm in response to BMP signals. In turn, BMPs in concert with Sox9, Sox6, and L-Sox5 would be responsible for the execution and maintenance of the cartilage differentiation program.     

Zebrafish msxB, msxC and msxE function together to refine the neural-nonneural border and regulate cranial placodes and neural crest development

The zebrafish muscle segment homeobox genes msxB, msxC and msxE are expressed in partially overlapping domains in the neural crest and preplacodal ectoderm. We examined the roles of these msx genes in early development. Disrupting individual msx genes causes modest variable defects, whereas disrupting all three produces a reproducible severe phenotype, suggesting functional redundancy. Neural crest differentiation is blocked at an early stage. Preplacodal development begins normally, but placodes arising from the msx expression domain later show elevated apoptosis and are reduced in size. Cell proliferation is normal in these tissues. Unexpectedly, Msx-deficient embryos become ventralized by late gastrulation whereas misexpression of msxB dorsalizes the embryo. These effects appear to involve Distal-less (Dlx) protein activity, as loss of dlx3b and dlx4b suppresses ventralization in Msx-depleted embryos. At the same time, Msx-depletion restores normal preplacodal gene expression to dlx3b-dlx4b mutants. These data suggest that mutual antagonism between Msx and Dlx proteins achieves a balance of function required for normal preplacodal differentiation and placement of the neural-nonneural border.     

Bacterial flora in the alimentary tract of chickens infected with Eimeria brunetti and in chickens immunized with Eimeria maxima and cross-infected with Eimeria brunetti

Differential bacterial counts were made on the intestinal and caecal contents of chickens after inoculation with a standard dose of 320 000 freshly sporulated oocysts of Eimeria brunetti.     

Parasites, emerging disease and wildlife conservation

In this review some emerging issues of parasite infections in wildlife, particularly in Australia, are considered. We discuss the importance of understanding parasite biodiversity in wildlife in terms of conservation, the role of wildlife as reservoirs of parasite infection, and the role of parasites within the broader context of the ecosystem. Using a number of parasite species, the value of undertaking longitudinal surveillance in natural systems using non-invasive sampling and molecular tools to characterise infectious agents is illustrated in terms of wildlife health, parasite biodiversity and ecology.     

Phylogenetic relationships among Southeast Asian climbing bamboos (Poaceae: Bambusoideae) and the Bambusa complex

A phylogenetic analysis of Bambusa and allies based on the plastid DNA non-coding regions rps16-trnQ, trnC-rpoB, trnH-psbA and trnD-T, and a partial nuclear GBSSI gene, was carried out. This included representatives from all four Bambusa subgenera (including type species), a group of segregate Southeast Asian genera distinctive by their climbing–scrambling culms (Dinochloa, Holttumochloa, Kinabaluchloa, Maclurochloa, Soejatmia, Sphaerobambos), and two other Bambusinae genera (Dendrocalamus, Gigantochloa). The results do not support the present subgeneric classification of Bambusa. The climbing Southeast Asian genera, all of which include species previously placed in Bambusa, are distinct from the “core Bambusa group” (type species and alliance) and the Bambusa complex generally.     

Gene expression in spider appendages reveals reversal of exd/hth spatial specificity, altered leg gap gene dynamics, and suggests divergent distal morphogen signaling

Leg development in Drosophila has been studied in much detail. However, Drosophila limbs form in the larva as imaginal discs and not during embryogenesis as in most other arthropods. Here, we analyze appendage genes in the spider Cupiennius salei and the beetle Tribolium castaneum. Differences in decapentaplegic (dpp) expression suggest a different mode of distal morphogen signaling suitable for the specific geometry of growing limb buds. Also, expression of the proximal genes homothorax (hth) and extradenticle (exd) is significantly altered: in the spider, exd is restricted to the proximal leg and hth expression extends distally, while in insects, exd is expressed in the entire leg and hth is restricted to proximal parts. This reversal of spatial specificity demonstrates an evolutionary shift, which is nevertheless compatible with a conserved role of this gene pair as instructor of proximal fate. Different expression dynamics of dachshund and Distal-less point to modifications in the regulation of the leg gap gene system. We comment on the significance of this finding for attempts to homologize leg segments in different arthropod classes. Comparison of the expression profiles of H15 and optomotor-blind to the Drosophila patterns suggests modifications also in the dorsal-ventral patterning system of the legs. Together, our results suggest alterations in many components of the leg developmental system, namely proximal-distal and dorsal-ventral patterning, and leg segmentation. Thus, the leg developmental system exhibits a propensity to evolutionary change, which probably forms the basis for the impressive diversity of arthropod leg morphologies.