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1.
溯江产卵洄游中的刀鲚是目前长江最为名贵的水产品之一。本文分析了2009年4~5月采自长江九段沙、靖江和芜湖3个江段的299尾洄游型刀鲚样本。结果显示,3个群体的体长范围为15.8~32.8(平均23.32?3.49)cm,18~24cm体长组占总数的52.51%。体重范围为11.83~143.8 (平均48.19?24.89) g,10~50g体重组占总数的59.53%。芜湖群体的体长和体重均显著小于九段沙和靖江群体(ANOVA, p=0.000<0.001)。299尾个体包括1~4龄4个年龄组,其中51.28%的九段沙个体和53.97%的靖江个体均为3龄;而多达85.26%的芜湖个体则为2龄。不论体长、体重还是年龄结构,已较上世纪70年代同江段渔获物有明显下降。结果还显示,研究样本的雌雄性比为1:1.57,九段沙、靖江和芜湖群体的性比分别为1:1.28、1:1.46和1:1.97,显示出沿长江往上性比逐渐增加的现象。3个群体的平均丰满度为0.35?0.049,但即使是在同龄组间,靖江群体的丰满度也显著高于芜湖和九段沙群体,这可作为大个体刀鲚在这一江段最名贵高价的一种解释。  相似文献   

2.
叶尔羌高原鳅的年龄、生长与繁殖特征   总被引:3,自引:0,他引:3  
分析了2008年5月采自新疆克孜河264尾叶尔羌高原鳅(Triplophysa yarkandensis)的年龄结构、生长特征和繁殖力。结果显示,种群年龄由2~11龄组成,其中2~4龄组个体占94.49%。平均体长和体重雌性为(9.39±2.10)cm和(16.55±15.85)g,雄性为(9.17±2.27)cm和(15.38±15.20)g,两者在雌雄群体间差异均不显著(P0.05)。体长和体重关系式为W♀+♂=0.014 0L2.988 9(r=0.975 4),W♀=0.016 7L2.889 5(r=0.980 9),W♂=0.011 7L3.083 1(r=0.975 7)。生长指标和年增重均以4龄组最大,分别为1.86和18.79 g/年。雌雄性比为0.7∶1.0。2龄性即成熟。最小成熟体长和体重雌性为6.2 cm和4.46 g,雄性为4.6 cm和1.67 g。绝对怀卵量为6 136~405 555(平均28 716±42 698)粒,相对怀卵量为672~6 134(平均2 310±1 427)粒/g。卵径呈单峰型分布,推测为不分批产卵类型。依据同年8月采集的19尾幼体日龄推算,其繁殖期为5月下旬至6月下旬。  相似文献   

3.
池养刀鲚(Coilia nasus)鱼种的摄食与生长   总被引:4,自引:0,他引:4  
采用生长测量、摄食节律评估的方法研究了人工养殖备件下刀鲚(Coilia nasus)的摄食和生长特性,旨在为刀鲚积累基础生物学资料,同时为大规模开展刀鲚的池塘养殖提供参考.结果表明:经过153 d的生长期,刀鲚的平均体长从最初的(12.41±2.21 )cm增加到(21.25±2.08)cm,体重从(5.83±0.91)g增加到(40.58±12.98)g;体长与日龄为线性相关(L=0.0558t+13.102,R2=0.97),体重与日龄为指数相关(W=6.5699e0.01231,R2 =0.98),体重与体长之间呈幂函数关系(W=0.0006L3.5924)幂指数b值接近3;刀鲚鱼种有明显的昼夜摄食节律,4:00-8:00是刀鲚鱼种的摄食高峰期,12:00左右摄食活动基本停止,16:00起摄食强度又明显回升,属晨昏摄食;此外还发现,枝角类、桡足类、日本沼虾和(鱼叚)虎鱼是培育刀鲚鱼种较为适宜的饵料生物,但其不同发育阶段适宜饵料生物有所不同,摄食量与饵料的种类和数量有直接关系.  相似文献   

4.
长江口是中国日本鳗鳗苗的主要产区和仅存的成鳗渔业水域。日本鳗自长江河口至上游金沙江近3000km干流及许多支流中都有分布,但其迁移行为却不为人了解。该文分析了2008年9~11月采自长江靖江段(31o30′N,120o42′E)的153尾银色鳗样本的生物学特征,测定了其中27尾标本的矢耳石Sr/Ca值。结果显示,153尾样本中有雌性85尾、雄性68尾,雌雄性比1:0.8。雌性由3~7(平均5.52)龄组成,平均体长(669±80)mm,体重(555±229)g,丰满度1.77±0.22,性腺指数(GSI)1.32±0.31。雄性由3~5(平均4.38)龄组成,平均体长(518±51)mm,体重(234±76)g,丰满度1.62±0.18,GSI0.21±0.11。雌性的这些生物学参数均显著大于雄性(P<0.05)。依据矢耳石线鳗标志轮平均Sr/Ca值(7.99±1.05)×10-3进行判断,有17尾(即62.96%个体)为"淡水型",10尾(即37.04%个体)为"河口型"。16尾雌性中有13尾(即81.25%)为"淡水型",3尾为"河口型"。11尾雄性中仅36.36%为"淡水型",63.64%为"河口型"。对每个生长层组的Sr/Ca值分析表明,雌雄间2龄时无显著差异,但3龄、4龄和洄游龄组都有显著或极显著的差异,预示着2龄时两者的栖息水域比较一致,但后来出现了明显栖息地分化。  相似文献   

5.
长江宜昌段鲢的繁殖生物学特征   总被引:1,自引:0,他引:1       下载免费PDF全文
2014年3月至2016年9月在长江中下游宜昌江段共收集鲢(Hypophthalmichthys molitrix)样本433尾,进行繁殖生物学研究。该江段鲢的繁殖时间为每年的5月下旬至8月上旬,以6~7月为盛产期。繁殖群体体长310~927 mm,体重600~17 090 g,由3~7龄共5个年龄组组成,3龄群体数量上占绝对优势,占繁殖群体的45.2%。雌雄性比为1.43︰1,雌雄群体间体长-体重关系存在显著性差异(0.01P0.05)。采用Logistic方程推算出初次性成熟雌性个体体长为482.3 mm,体重为2 206.7 g;初次性成熟雄性个体体长为484.0 mm,体重1 677.5 g。卵径(1.01±0.12)mm,大小分布呈单峰型,为单批产卵型鱼类。绝对繁殖力(477 662±9 631)粒,相对繁殖力为(93.38±5.92)粒/g,绝对繁殖力随着鱼体长、体重增长而增大。与其他地理种群相比较,宜昌江段鲢总体表现为卵径相对较小而繁殖力较大。  相似文献   

6.
高体近红鲌的生长与繁殖   总被引:1,自引:0,他引:1  
高体近红鲌为长江上游的特有鱼类,以2008年5—11月从赤水河赤水市江段采集的540尾高体近红鲌标本为材料,对其生长与繁殖特性进行了研究和分析。结果表明:高体近红鲌鳞片年轮结构呈疏密切割型,年龄特征显著。种群由1—4龄共4个年龄组组成,其中以2龄个体为主。体长分布主要集中在100—160 mm;体重分布主要集中在20.0—50.0 g。总性比为♀∶♂=1.30∶1。体长与鳞径呈直线关系,体长和体重呈幂函数关系且幂指数接近3,基本符合匀速生长类型,体长和体重Von Bertalanffy方程分别为Lt=217.38(1-e-0.2867(t+0.757))和Wt=118.15[1-e-0.2867(t+0.757)]2.8103;生长拐点为2.85龄,拐点对应的体长和体重分别为Lt=140.09 mm,Wt=34.37 g。雌雄初次性成熟年龄均为1龄;繁殖高峰期为6—7月。Ⅳ期雌鱼的绝对繁殖力为950—8655粒,平均值(3087.90±1602.15)粒;体长相对繁殖力FL为10.00—56.20粒/cm,平均值(24.26±10.16)粒/cm;体重相对怀卵量FW为66.08—197.67粒/g,平均值(1...  相似文献   

7.
为调查短颌鲚(Coilia nasus) 在三峡库区的资源现状, 自2019年7—12月于三峡库区的长江一级支流澎溪河、梅溪河、草堂河、大宁河共采集短颌鲚样本459尾, 用以分析三峡库区现有短颌鲚的年龄结构及生长特征。研究结果显示, 三峡库区短颌鲚群体由1—6龄组成, 1龄即可达性成熟, 群体中1—3龄个体占比90.85%; 群体平均体长为(16.57±0.21) cm, 平均体重为(19.14±0.78) g; 群体的体重-体长关系式为W=0.0038L2.957 (R2=0.99), 属于异速生长类型; 雌性的Von Bertalanffy生长方程为Lt=38.567[1–e–0.196(t+0.985)], Wt=183.029[1–e–0.196(t+0.985)]2.938; 雄性的Von Bertalanffy生长方程为Lt=34.711[1–e–0.26(t+0.603)], Wt=143.599[1–e–0.26(t+0.603)]2.995; 雌、雄性体重生长的拐点年龄分别为4.62龄和3.62龄。研究结果表明目前三峡库区短颌鲚属个体小型化群体, 年龄结构简单, 种群数量呈上升趋势, 且群体中雌性占比较高, 繁殖潜力充足。因此, 为保护三峡库区水域生态系统的安全与稳定, 需进一步开展有关短颌鲚对三峡库区水域生态系统的影响及其风险评价的研究。  相似文献   

8.
《生命科学研究》2016,(2):135-139
比较分析了不同水域刀鲚的分类地位,生殖洄游时间、路线和所需外界条件以及其分布现状和资源状况。同时,于2015年对鄱阳湖、赣江和抚河下游的刀鲚进行了现场调查,并与1982年采自鄱阳湖的刀鲚标本进行了生物学特性比较。研究发现,1982年鄱阳湖短颌鲚(定居型刀鲚)体长范围为5.0~30.0 cm,优势组体长为6~20 cm,体重范围是0.90~105.08 g;2015年调查的短颌鲚体长范围为11.6~28.0 cm,优势组体长为11~20 cm,体重范围为5.99~81.31 g。1982年鄱阳湖洄游型刀鲚占总尾数的3.86%,体长范围为15.0~33.0 cm,体重范围为10.24~151.63 g;而2015年调查的洄游型刀鲚仅占总尾数的0.97%,体长范围是25.5~28.0 cm,体重范围是60.62~78.00 g。结果分析表明,江西上述水域均以短颌鲚为主,洄游型刀鲚难已形成渔汛。  相似文献   

9.
长江刀鲚不同生态型间的某些形态差异   总被引:6,自引:1,他引:6       下载免费PDF全文
摘要:为寻找和检验长江刀鲚(Coilia nasus)不同生态型间的形态差异,分析了江苏靖江、上海九段沙、浙江太湖和江西鄱阳湖4个种群906尾样本的脊椎骨数、臀鳍条数和上颌骨长。结果表明,即使是同一种群内的脊椎骨数和臀鳍条数变幅也较大,但均以靖江和九段沙种群的较多,众数分别为81、80和108、109;太湖和鄱阳湖种群...  相似文献   

10.
利用2018年6月—2019年5月湖北省堵河306尾宽鳍■Zacco platypus的调查数据,研究了该水域宽鳍■的种群结构和繁殖力特征。结果显示:堵河宽鳍■种群由3个年龄组组成,Ⅱ龄为优势年龄组,占种群总数的55.2%。体长、体质量分布区间分别为64~203 mm、4.0~106.8 g,平均体长、体质量分别为125 mm±24 mm和34.3 g±18.2 g, 87.1%的体长集中在82~154 mm, 70.3%的体质量集中在14.4~45.7 g。堵河水系宽鳍■种群的雌雄比为0.53∶1,Ⅰ龄、Ⅱ龄和Ⅲ龄组的分别为0.76∶1、0.40∶1和0.63∶1,其中,堵河水系宽鳍■种群和Ⅱ龄组的实际雌雄比与理论值(1∶1)之间的差异有统计学意义(P0.05)。雌雄个体的成熟系数周年变化明显,且具有明显的种内雌雄差异,雌性个体较雄性明显偏大。繁殖活动主要发生于4—7月,且雌性个体的繁殖活动存在一定的空白期。雌性个体的平均卵质量和卵径分别为1.34 mg±0.53 mg和1.14 mm±0.24 mm,绝对繁殖力变化范围为864~5 074粒,均值为1 863.74粒±1 097.86粒,绝对繁殖力与体长、体质量、空壳质量以及性腺质量均具有显著相关关系(P0.05),但与全长相关性不显著(P0.05)。  相似文献   

11.
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.  相似文献   

12.
Parasitic nematodes from the Berlin (ZMB) and Vienna (NMW) Museum collections referred to the genus Filaria Mueller, 1787 by von Linstow or Molin were studied. Three samples were in good condition and the specimens redescribed. Litomosa hepatica (von Linstow, 1897) n. comb., sample ZMB Vermes Entozoa 3368, from the megachiropteran Pteropus neohibernicus, Bismarck Archipelago, resembles L. maki Tibayrenc, Bain & Ramanchandran, 1979, from Pteropus vampyrus, in Malaysia, but the buccal capsule differs. Both species display particular morphological characters which differ from species of Litomosa parasitic in microchiropterans. The remaining material originates from Brazil. The spicule morphology of Litomosoides circularis (von Linstow, 1899) Chandler, 1931, sample ZMB Vermes Entozoa 1059 from Hesperomys spec. (= Holochilus brasiliensis), Porto Alegre, confirms that it belongs to the sigmodontis group; the microfilaria presents characters of the genus Litomosoides, e.g. body attenuated at both extremities and salient cephalic hook. Taxonomic discussions by others confirm that species of Litomosoides belonging to the sigmodontis group and described subsequently are distinct from L. circularis. Litomosoides serpicula (Molin, 1858) Guerrero, Martin, Gardner & Bain, 2002, is redescribed, sample NMW 6323 from the bat Phyllostoma spiculatum (= Sturnira lilium), Ypanema. It is very close to L. brasiliensis Almeida, 1936, type host Moytis sp., but distinguished by a single ring in the buccal capsule, rather than two, supporting previous conclusions that the taxon L. brasiliensis, as generally regarded, may represent a complex of species. Samples NMW 6322 and NMW 6324, from other bats and also identified by Molin (1858) as Filaria serpicula, contain unidentifiable fragments of Litomosoides incertae sedis. Filaria hyalina von Linstow, 1890, sample ZMB Vermes Entozoa Q 3905 from Sorer vulgaris (= Sorex araneus), is incertae sedis because it contains two unidentifiable posterior parts of male, which might be an acuarid, Stammerinema sp. Filaria vesperuginis von Linstow, 1885, sample ZMB Vermes Entozoa Q 3929, from the bat Vesperugo serotinus (= Eptesicus serotinus), contains encysted nematode larvae and is a nomen dubium.  相似文献   

13.
The late-third-instar labial disc is comprised of two disc-proper cell layers, one representing mainly the ventral half of the anterior compartment (L-layer) and the other, the dorsal half of the anterior compartment and most, if not all, of the posterior compartment (M-layer). In the L-layer, Distal-less represses homothorax whereas no Distal-less-dependent homothorax repression occurs in the M-layer where Distal-less is coexpressed with homothorax. In wild-type labial discs, clawless, one of the two homeobox genes expressed in distal cells receiving maximum (Decapentaplegic+Wingless) signaling activity in leg and antennal discs, is specifically repressed by proboscipedia. A fate map, inferred from data on basic patterning gene expression in larval and pupal stages and mutant phenotypes, indicates the inner surface of the labial palpus, which includes the pseudotracheal region, to be a derivative of the distal portion of the M-layer expressing wingless, patched, Distal-less and homothorax. The outer surface of the labial palpus with more than 30 taste bristles derives from an L-layer area consisting of dorsal portions of the anterior and posterior compartments, each expressing Distal-less. Our analysis also indicates that, in adults and pupae, the anterior-posterior boundary, dividing roughly equally the outer surface of the distiproboscis, runs along the outer circumference of the inner surface of distiproboscis.  相似文献   

14.
Microbial transformation of zaluzanin-D   总被引:2,自引:0,他引:2  
Microbial transformation of zaluzanin-D using different fungi gave 11,13-dihydrozaluzanin-C, zaluzanin-C, 4,16,11,13 - tetrahydro zaluzanin-C, estafiatone, dihydroestafiatol and dihydroestafiatone.  相似文献   

15.
16.
A broad multilocus phylogenetic analysis (MLPA) of the representative diversity of a genus offers the opportunity to incorporate concatenated inter-species phylogenies into bacterial systematics. Recent analyses based on single housekeeping genes have provided coherent phylogenies of Aeromonas. However, to date, a multi-gene phylogenetic analysis has never been tackled. In the present study, the intra- and inter-species phylogenetic relationships of 115 strains representing all Aeromonas species described to date were investigated by MLPA. The study included the independent analysis of seven single gene fragments (gyrB, rpoD, recA, dnaJ, gyrA, dnaX, and atpD), and the tree resulting from the concatenated 4705 bp sequence. The phylogenies obtained were consistent with each other, and clustering agreed with the Aeromonas taxonomy recognized to date. The highest clustering robustness was found for the concatenated tree (i.e. all Aeromonas species split into 100% bootstrap clusters). Both possible chronometric distortions and poor resolution encountered when using single-gene analysis were buffered in the concatenated MLPA tree. However, reliable phylogenetic species delineation required an MLPA including several “bona fide” strains representing all described species.  相似文献   

17.
Antennapedia is one of the homeotic selector genes required for specification of segment identity in Drosophila. Dominant mutations that ectopically express Antennapedia cause transformation of antenna to leg. Loss-of-function mutations cause partial transformation of leg to antenna. Here we examine the role of Antennapedia in the establishment of leg identity in light of recent advances in our understanding of antennal development. In Antennapedia mutant clones in the leg disc, Homothorax and Distal-less are coexpressed and act via spineless to transform proximal femur to antenna. Antennapedia is negatively regulated during leg development by Distal-less, spineless, and dachshund and this reduced Antennapedia expression is needed for the proper development of distal leg elements. These findings suggest that the temporal and spatial regulation of the homeotic selector gene Antennapedia in the leg disc is necessary for normal leg development in Drosophila.  相似文献   

18.
The present generic concept of Phoma is broadly defined, with nine sections being recognised based on morphological characters. Teleomorph states of Phoma have been described in the genera Didymella, Leptosphaeria, Pleospora and Mycosphaerella, indicating that Phoma anamorphs represent a polyphyletic group. In an attempt to delineate generic boundaries, representative strains of the various Phoma sections and allied coelomycetous genera were included for study. Sequence data of the 18S nrDNA (SSU) and the 28S nrDNA (LSU) regions of 18 Phoma strains included were compared with those of representative strains of 39 allied anamorph genera, including Ascochyta, Coniothyrium, Deuterophoma, Microsphaeropsis, Pleurophoma, Pyrenochaeta, and 11 teleomorph genera. The type species of the Phoma sections Phoma, Phyllostictoides, Sclerophomella, Macrospora and Peyronellaea grouped in a subclade in the Pleosporales with the type species of Ascochyta and Microsphaeropsis. The new family Didymellaceae is proposed to accommodate these Phoma sections and related anamorph genera. The present study demonstrated that Phoma radicina, the type species of Phoma sect. Paraphoma and Phoma heteromorphospora, the type species of Phoma sect. Heterospora can be assigned to the Phaeosphaeriaceae and Leptosphaeriaceae respectively.  相似文献   

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In eukaryotes, mature rRNA sequences are produced from single large (45S) precursor (pre-rRNA) as the result of successive removal of spacers through a series of rapid and intricate actions of endo- and exonucleases. The excision of internal transcribed spacer (ITS2), a eukaryotic-specific insertion, remains the most elusive processing step. ITS2 is the element mandatory for all eukaryotic pre-rRNAs that contain at least three processing cleavage sites for precise 5.8S and 28S formation. Conserved core sequences (cis-elements) binding to trans-factors provide for precise rRNA processing, whereas rapidly diverging regions between the core sequences preserve internal complementarity, which guarantees the spatial integrity of ITS2. Characteristic differences in the formation of such insertions during evolution should reflect the relationships between taxa. The phylogeny of the reptiles and the relationships between taxa proposed by scientists are controversial. To delineate the structural and functional features preserved among reptilian ITS2s, we cloned and sequenced 58 ITS2s belonging to four reptile orders: Squamata, Crocodilians, Aves, and Testudines. We studied the subsequent alignment and folding of variable regions. The sizes and packing of the loop–stems between conserved consensus segments in reptiles vary considerably between taxa. Our phylogenetic trees constructed on the basis of the reptile ITS2s primary structural alignments revealed a split between Iguania clade and all other taxa. True lizards (suborder Scleroglossa) and snakes (suborder Serpentes) show sister relationships, as well as the two other reptilian orders, Crocodilia + Aves and Testudines. In summary, our phylogenetic trees exhibit a mix of specific features deduced or, to the contrary, rejected earlier by other authors.  相似文献   

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