中华绒蟹幼体消化道甲壳质消化细菌的研究

1　引　　言随着中华绒螯蟹 (Eriocheirsinensis)人工育苗规模的扩大 ,生产实践中有关小型甲壳类活体饵料投喂问题受到生产者和一些学者的重视[1,3 ,4] ,本研究分析中华绒螯蟹幼体消化道内甲壳质消化细菌 ,试图从该方面探讨中华绒螯蟹幼体与甲壳类活体饵料动物之间的关系 .有关水生动物消化道内甲壳质消化细菌 ,曾在鱼胃中有发现 .中华绒螯蟹消化道内微生物的研究未见有报道 ,我们对中华绒螯蟹 氵蚤Ⅰ大眼幼体消化道内甲壳质消化细菌进行了分离筛选 ,以探讨其消化机理 ,并为人工育苗生产中合理选择时机投喂卤虫 (Artemiasalina)、枝角类等…     

果胶和木聚糖对中华绒螯蟹肠道菌群结构的影响

本研究旨在揭示果胶和木聚糖对中华绒螯蟹(Eriocheir sinensis)肠道菌群结构的影响。将果胶和麦麸(木聚糖源)分别以8%和30%的比例添加到饲料中制成试验饲料,将经过酶解的果胶和麦麸添加到饲料中制备成对照饲料,饲养初始体重为(5.9依0.4)g的中华绒螯蟹8周。养殖试验结束后,采用16S r DNA荧光定量PCR法分析测定了中华绒螯蟹肠道菌群结构。结果显示中华绒螯蟹肠道细菌主要由变形菌门(Proteobacteria)、厚壁菌门(Firmicutes)、拟杆菌门(Bacteroidetes)、梭杆菌门(Fusobacteria)的细菌组成。果胶组肠道菌群丰度指数Ace和Chao分别低于其对照组31%和39%,肠道菌群多样性指数Simpson比对照组高25%,而Shannon指数比对照组低48%。木聚糖组Ace和Chao指数均比果胶组高约25%,比其酶解对照组高约14%。木聚糖组的多样性指数与其酶解木聚糖组及果胶组的差异较小。上述结果表明,果胶和木聚糖均影响中华绒螯蟹肠道的菌群结构,但两者对肠道菌群丰度的影响不同。     

饲料中DHA含量对中华绒螯蟹幼蟹生长、脂类组成和低氧胁迫的影响

二十二碳六烯酸（C22:6n-3,DHA）对甲壳动物生长、蜕壳、性腺发育、免疫保护和抗环境胁迫具有重要的调节作用,探讨饲料中脂肪酸营养与中华绒螯蟹幼蟹生长和耐低氧胁迫的调控关系具有重要的理论意义和现实意义。通过单个体养殖试验、生化分析、低氧胁迫及生理指标测定等方法,研究了饲料中DHA含量对中华绒螯蟹幼蟹（初始均重为0.6g左右）成活、生长、脂类组成和低氧胁迫下生理指标的影响,探讨幼蟹饲料中适宜的DHA含量。结果表明:（1）饲料中DHA含量对中华绒螯蟹幼蟹的成活、生长、蜕壳和肝胰腺指数无显著影响;（2）饲料中DHA含量对幼蟹肝胰腺水分、肌肉水分及总脂含量均无显著影响,但饲料中过量DHA（0.81%）导致幼蟹肝胰腺总脂含量显著升高;（3）幼蟹肝胰腺和肌肉中的DHA均随着饲料中DHA含量升高而显著上升,但DHA相对保留率（组织中DHA与饲料中DHA的比值）随着饲料中DHA含量上升而显著下降,整体上肌肉中各PUFA的相对保留率远高于肝胰腺。无论饲料中DHA/EPA比值如何变化,肌肉中DHA/EPA均小于1,这说明幼蟹肌肉需要更多的EPA;（4）饲料中添加适量的DHA（0.18%0.28%）可以提高低氧胁迫下幼蟹血淋巴中超氧化物歧化酶的活性,降低其乳酸和丙二醛含量,从而提高幼蟹的抗低氧胁迫能力。综上,中华绒螯蟹幼蟹饲料中适宜DHA含量为0.2%左右。       

基于稳定同位素的黄河三角洲盐碱地稻蟹种养系统中华绒螯蟹食物源分析

为探讨盐碱地稻蟹种养系统中华绒螯蟹食物源构成,2020年6—10月,在山东东营垦利区,采集稻田中华绒螯蟹及其所有可能食物来源样品,包括植物(伊乐藻、菹草、金鱼藻、浮萍、水稻茎叶、稻谷)、动物(底栖动物、浮游动物)、有机碎屑和人工饲料(配合饲料、玉米粕),并利用碳、氮稳定同位素(δ¹³C和δ¹⁵N)值进行分析,定量其在中华绒螯蟹食物组成中的贡献率。结果表明: 食物源样品δ¹³C值范围为-30.09‰～-11.24‰,δ¹⁵N值范围为0.03‰～12.78‰,不同食物源δ¹³C和δ¹⁵N值呈现明显差异。中华绒螯蟹肌肉中δ¹³C值变化范围为-24.61‰～-20.08‰,δ¹⁵N值变化范围为4.74‰～9.21‰,表明稻蟹种养系统中华绒螯蟹食物来源较丰富。养殖期间各食源贡献率为植物(46.7%～57.1%)>动物(21.5%～24.5%)>人工饲料(10.9%～21.3%)>有机碎屑(7.1%～7.9%)。可见,盐碱地稻田系统天然饵料基本能够满足中华绒螯蟹摄食需求,即使本试验投喂非动物性人工饵料,也未改变中华绒螯蟹主要食源贡献率。     

三种饵料模式对中华绒螯蟹蟹种早期养殖性能、非特异免疫性能及抗病力的影响

为评估不同投喂模式对中华绒螯蟹(Eriocheir sinensis)蟹种质量的影响,采用养殖实验、非特异性免疫指标分析和攻毒实验方法,比较了配合饲料、传统饵料和混合投喂模式培育扣蟹在成蟹养殖早期的养殖性能、免疫性能和攻毒后死亡率的变化。所检测的非特异性免疫指标包括碱性磷酸酶(ALP)、酸性磷酸酶(ACP)、γ-谷氨酰转移酶(γ-GT)、总抗氧化能力(T-AOC)、超氧化物歧化酶(SOD)、酚氧化酶(PO)、过氧化物酶(POD)、丙二醛(MDA)、一氧化氮(NO)、谷胱甘肽过氧化物酶(GSH-Px)、谷胱甘肽还原酶(GR)及血蓝蛋白(Hc)活性或含量。采用毒力较强的嗜水气单胞菌(Aeromonas hydrophilia)Y-2-L-1菌株进行攻毒实验。结果显示:(1)无论雄蟹还是雌蟹,配合饲料组第一次蜕壳间期均短于传统投喂和混合投喂模式,且配合饲料组增重率(WGR)及体重特定增长率(SGR)均显著高于另外两组(P0.05);(2)就肝胰腺中非特异性免疫指标而言,无论雄蟹还是雌蟹,配合饲料组γ-谷氨酰转移酶(γ-GT)、总抗氧化能力(T-AOC)和超氧化物歧化酶(SOD)活性均高于另外两组,其中γ-谷氨酰转移酶(γ-GT)差异显著;传统投喂组酸性磷酸酶(ACP)、丙二醛(MDA)、一氧化氮(NO)和过氧化物酶(POD)含量均高于另外两组,其中酸性磷酸酶(ACP)和一氧化氮(NO)含量差异显著;(3)就血清中各免疫指标而言,配合饲料组谷胱甘肽过氧化物酶(GSH-Px)和总抗氧化能力(T-AOC)活性高于另外两组,但差异均不显著(P0.05),传统投喂组碱性磷酸酶(ALP)、酸性磷酸酶(ACP)、丙二醛(MDA)及血蓝蛋白(Hc)等指标含量均高于另外两组,其中丙二醛(MDA)差异显著;(4)无论雄蟹还是雌蟹,传统投喂组扣蟹攻毒后12~96 h的累计死亡率一直高于配合饲料组和混合投喂组,配合饲料组和混合投喂组雄体攻毒后的累计死亡率接近,混合投喂组雌体累计死亡率居于传统投喂组和配合饲料组之间。综上,投喂配合饲料可以提高扣蟹在成蟹早期的养殖性能、免疫性能和攻毒后的成活率,有利于提高蟹种质量。     

低氧胁迫和螺原体感染对中华绒螯蟹存活和细胞凋亡的影响

为了探究低氧胁迫对螺原体(Spiroplasma eriocheiris)感染中华绒螯蟹(Eriocheir sinensis)的影响, 以中华绒螯蟹为研究对象, 在低氧胁迫后, 取中华绒螯蟹肝胰腺和鳃组织加入组织固定液, 进行HE染色。在低氧条件下使螺原体感染中华绒螯蟹, 计算螺原体拷贝数, 并对血淋巴细胞进行细胞凋亡、细胞坏死和线粒体膜电位检测。结果显示, 与对照组相比, 处于长时间低氧胁迫状态下的中华绒螯蟹肝胰腺组织疏松, 出现大量小空泡, 鳃轴结构弥散, 组织结构被破坏。此外, 低氧组的中华绒螯蟹感染螺原体后的死亡速度相对于常氧组明显加快, 血细胞内的螺原体数量、线粒体膜电位、血细胞凋亡率和坏死率相较于常氧组均显著升高。以上研究说明低氧胁迫可以加速螺原体的感染, 使河蟹死亡速度变快, 使血淋巴细胞凋亡和坏死更显著, 不利于河蟹的生理生化。     

混合植物油替代鱼油对中华绒螯蟹成体雄蟹常规成分和脂肪酸组成的影响

为研究育肥饲料中混合植物油替代鱼油对中华绒螯蟹(Eriocheir sinensis)成体雄蟹常规成分和脂肪酸组成的影响,采用豆油和菜籽油混合物替代鱼油制成5种不同鱼油替代水平(0%、25%、50%、75%和100%)的等氮等脂育肥饲料(分别记为1#~5#饲料组)饲喂雄蟹,测定5组雄蟹肝胰腺、肌肉和性腺中的常规成分和脂肪酸组成,并对实验数据进行方差分析。结果显示:(1)饲料1#组性腺灰分含量显著高于饲料4#和5#组(P0.05),但各组性腺中的水分、总脂和蛋白含量均无显著差异(P0.05);饲料1#组肝胰腺中的水分和灰分最高,但其总脂含量低于其他组,各组肝胰腺的蛋白含量无显著差异(P0.05);除1#饲料组外,肌肉中的总脂和灰分含量随鱼油替代水平的升高而显著上升(P0.05),而水分和蛋白含量均无显著差异(P0.05)。(2)各饲料组精巢中总饱和脂肪酸(∑SFA)、总多不饱和脂肪酸(∑PUFA)和总高度不饱和脂肪酸(∑HUFA)含量无显著差异(P0.05),其总n-6多不饱和脂肪酸(∑n-6PUFA)含量随鱼油替代水平升高而升高,而总n-3多不饱和脂肪酸(∑n-3PUFA)含量和∑n-3PUFA/∑n-6PUFA比值呈显著下降趋势(P0.05)。(3)肝胰腺中∑n-3PUFA和∑HUFA含量具有显著的组间差异,且均以饲料3#组最高。但各组的∑PUFA和∑n-6PUFA含量差异并不显著(P0.05)。(4)肌肉中大部分脂肪酸组成无显著差异,仅∑n-6PUFA含量随鱼油替代水平升高而升高。综上,中华绒螯蟹育肥饲料中植物油(豆油与菜籽油含量为1︰1)替代鱼油对成体雄蟹可食组织中水分和蛋白含量并无显著影响,但会对其脂肪酸组成造成显著的影响,50%的鱼油替代水平有利于雄蟹肝胰腺和肌肉中的脂肪沉积。     

饲料中添加合成虾青素对中华绒螯蟹成体雌蟹性腺发育、色泽和抗氧化能力的影响

采用在基础饲料中分别添加0、130和260 mg/kg的合成虾青素配制成3种粗蛋白和粗脂肪含量分别为42%和16%的等氮等脂的中华绒螯蟹(Eriocheir sinensis)育肥饲料(分别记为饲料1、2和3), 以中华绒螯蟹商业育肥饲料作为饲料4, 分别投喂4组雌蟹(每个饲料组3个重复水槽, 每个水槽中12只蟹), 进行为期60d的室内养殖实验, 以探讨添加合成虾青素对中华绒螯蟹成体雌蟹性腺发育、色泽及抗氧化能力的影响。结果显示: (1)实验进行到30d和60d, 在饲料中添加虾青素对雌体肝胰腺指数(HSI)和性腺指数(GSI)均无显著影响(P>0.05)。(2)性腺、肝胰腺和头胸甲中的总类胡萝卜素含量和红度值(a值)均以饲料3组最高, 性腺亮度值(L值)和黄度值(b值)以饲料1组最高(P<0.05); 饲料2组头胸甲的b值最高, 饲料1组最低(P<0.05)。(3) 饲料1组中华绒螯蟹血清过氧化物酶(POD)活性显著高于其他组, 饲料4组的过氧化氢酶(CAT)、谷胱甘肽还原酶(GR)、乳酸脱氢酶(LDH)、总抗氧化能力(T-AOC)、丙二醛(MDA)和乳酸(LD)含量最高(P<0.05); 肝胰腺中的SOD、T-AOC、GSH-Px和GR活性均以饲料1组最高, 饲料2组最低(P<0.05)。(4) 饲料2组血清酸性磷酸酶(ACP)活性和血蓝蛋白(Hc)含量显著高于其他组, 其余各组间差异不显著。血清中的碱性磷酸酶(ALP)和γ-谷氨酰转移酶(γ-GT)活性和一氧化氮(NO)含量均以饲料4组最高(P<0.05), 肝胰腺中的ACP、ALP和γ-GT活性以饲料1组最高。综上, 在育肥饲料中添加合成虾青素对成体雌蟹性腺发育无显著影响, 但可显著提高头胸甲、肝胰腺和卵巢中的类胡萝卜素总量、色泽和抗氧化能力, 建议雌蟹育肥饲料中合成虾青素的含量为90 mg/kg左右。     

饲料中不同淀粉水平对中华绒螯蟹幼蟹生长、饲料利用的影响

实验配制7种等氮(粗蛋白35%)、等脂(粗脂肪6%)的不同淀粉水平(4%、10%、16%、22%、28%、34%、40%)的饲料,投喂中华绒螯蟹(Eriocheir sinensis)幼蟹[初始均重(6.2±0.1)g]8周,通过生长和生理指标评价中华绒螯蟹幼蟹对饲料碳水化合物的利用能力。为避免互相残杀,河蟹采用静水单个养殖,每种饲料40只河蟹。玉米淀粉作为实验饲料碳水化合物主要来源。实验结果表明:饲料中34%—40%淀粉组的摄食率显著低于4%—16%组(P0.05)。随饲料中淀粉含量提高幼蟹的体重和壳长特定生长率也相应提高,34%淀粉组体重特定生长率显著高于4%淀粉组(P0.05),22%淀粉组的壳长特定生长率显著高于4%淀粉组(P0.05);饲料中淀粉含量的增加显著提高了饲料效率,且在40%淀粉组最高。饲料高淀粉可提高蛋白储积率,蟹的肝体比在16%淀粉组最低,而蜕壳率和成活率在该组最高。蟹体干物质、粗蛋白、粗脂肪和灰分在高饲料淀粉组较高。幼蟹胰蛋白酶活力在16%淀粉组最高(P0.05);肝糖原含量随饲料淀粉水平升高呈线性(y=0.2268x+17.256,R2=0.9453,n=7,P0.05)上升。通过二次多项式回归可以得出河蟹获得最大特定生长率时饲料淀粉的含量为25.6%。     

中华绒螯蟹MSTN基因SNPs多态性及与生长性状的关联分析

为研究中华绒螯蟹(Eriocheir sinensis)肌肉生长抑制素基因(myostatin, MSTN)的多态性及其与生长性状的相关性, 对中华绒螯蟹3个群体(育种群体、大赛群体、野生群体)共321个个体MSTN基因的多态性进行筛选, 发现该基因的第1外显子存在3个多态性SNP位点(S1: C714T; S2:G729A; S3:G753T), 均为处于Hardy-Weinberg平衡(P>0.05)的中、高度多态性位点。利用一般线性模型分析3个位点及其基因型组合与生长性状的相关性, 发现S1位点对中华绒螯蟹的体重和壳长等生长性状有显著影响(P≤0.05), 而其余2个位点与生长性状无显著关联性。结果表明S1位点的TT基因型对中华绒螯蟹的生长最为有利, 可作为分子标记辅助育种的候选标记。     

Plant-Parasitic Nematodes of South Viet Nam

Between 1974 and 1978, 2,842 identifications of plant-parasitic nematodes were made from more than 1,700 soil and plant samples collected in eight provinces of South Viet Nam. Species in nine genera—Helicotylenchus, Criconemoides, Meloidogyne, Pratylenchus, Tylenchorhynchus, Hoplolaimus, Hirschmanniella, Xiphinema, and Rotylenchulus—comprised 96.1% of the identifications; the remaining 3.9% were species of 11 genera. Fourteen genera were associated with rice which was grown on about 2,500,000 ha in 1970. Of these, Ditylenchus, Hirschmanniella, and Meloidogyne were most important. Ditylenchus angustus caused severe damage to about 50,000 ha of flooded rice in the Mekong Delta in 1976. Hirschmanniella spp. were found in all samples examined from flooded rice fields. Meloidogyne spp. were common in rice seedbeds, upland rice, and rice not kept flooded continuously. Meloidogyne and Pratylenchus spp. were found in roots of 22 of the 32 crop plants sampled. Little or no attempt was made in South Viet Nam to control nematodes.     

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.     

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.     

The identification of microRNAs in the whitespotted bamboo shark (Chiloscyllium plagiosum) liver by Illumina sequencing

MicroRNAs are indispensable players in the regulation of a broad range of biological processes. Here, we report the first deep sequencing of the whitespotted bamboo shark (Chiloscyllium plagiosum) liver. We mapped 91 miRNAs in the Callorhinchus milii genome that have previously been described in the Danio rerio, Fugu rubripes, Oryzias latipes, Xenopus laevis, Xenopus tropicalis, Homo sapiens, and Mus musculus. In addition, 156 new putative candidate (PC) C. plagiosum miRNAs were identified. From these 247 miRNAs, 39 miRNA clusters were identified, and the expression of these clustered miRNAs was observed to vary significantly. A total of 7 candidate miRNAs were selected for expression confirmation by stem-loop RT-PCR. This study resulted in the addition of a significant number of novel miRNA sequences to GenBank and laid the foundation for further understanding of the function of miRNAs in the regulation of C. plagiosum liver development.     

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.