稳定同位素技术分析不同养殖方式下鳙饵料的贡献率

应用碳氮稳定同位素技术分析了不同养殖方式(A组:施肥;B组:施肥+1/2投饲;C组:施肥+投饲;D组:投饲)围隔中鳙(Aristichthys nobilis)肌肉碳氮稳定同位素变化情况,及其可能摄食饵料的贡献率。结果表明,A组鳙肌肉的δ13C和δ15N值分别为(–23.8±0.1)‰和(10.8±0.4)‰,显著高于B组、C组和D组的值(P0.05),后三者之间值没有显著差异。围隔中的食物源有浮游动物、颗粒有机物和饲料,它们的δ13C和δ15N值均低于消费者鳙的同位素值。3种食物在不同养殖方式下的贡献率不同,浮游动物是A组鳙的主要食物来源,平均贡献率为(65.6±3.2)%,饲料是另3个组鳙的主要食物来源,其中B组饲料的贡献率相对较大,达82.1%。说明投饲鳙后,鳙对饲料能够较好地吸收利用,但在池塘中同时培育天然饵料能有效提高饲料的贡献率,减少投饲量,降低残饵的污染。本研究旨为实践养殖中合理投饲鳙的管理技术提供理论依据。     

Multilocus sequence typing detects new Piscirickettsia salmonis hybrid genogroup in Chilean fish farms: Evidence for genetic diversity and population structure

Piscirickettsia salmonisis the causative bacterial pathogen of piscirickettsiosis, a salmonid disease that causes notable mortalities in the worldwide aquaculture industry. Published research describes the phenotypic traits, virulence factors, pathogenicity and antibiotic‐resistance potential for various P. salmonisstrains. However, evolutionary and genetic information is scarce for P. salmonis. The present study used multilocus sequence typing (MLST) to gain insight into the population structure and evolution of P. salmonis. Forty‐two Chilean P. salmonisisolates, as well as the type strain LF‐89^T, were recovered from diseased Salmo salar, Oncorhynchus kisutchand Oncorhynchus mykissfrom two Chilean Regions. MLST assessed the loci sequences of dnaK, efp, fumC, glyA, murG, rpoD and trpB. Bioinformatics analyses established the genetic diversity among P. salmonis isolates (H = 0.5810). A total of 23 sequence types (ST) were identified, 53.48% of which were represented by ST1, ST5 and ST2. Population structure analysis through polymorphism patterns showed few polymorphic sites (218 nucleotides from 4,010 bp), while dN/dS ratio analysis indicated purifying selection for dnaK, epf, fumC, murG, and rpoD but neutral selection for the trpB loci. The standardized index of association indicated strong linkage disequilibrium, suggesting clonal population structure. However, recombination events were detected in a group of seven isolates. Findings included genogroups homologous to the LF‐89^T and EM‐90 strains, as well as a seven‐isolate hybrid genogroup recovered from both assessed regions (three O. mykiss and four S. salar isolates). The presented MLST scheme has comparative potential, with promising applications in studying distinct P. salmonis isolates (e.g., from different hosts, farms, geographical areas) and in understanding the epidemiology of this pathogen.     

Fertilization rate,motility, lipid peroxidation and pH changes after chilled storage of rainbow trout (Oncorhynchus mykiss) eggs and spermatozoa by a RMPI medium

The aim of this study was to evaluate the effects of Roswell Park Memorial Institute (RPMI) 1,640 medium on chilled storage of eggs and spermatozoa of rainbow trout (Oncorhynchus mykiss). After 3 days of storage, eggs in RPMI 1,640 media (pH 8.2, 9 and 10), Cortland medium and coelomic fluid were inseminated with fresh spermatozoa (Experiment 1). Eggs in RPMI 1,640 medium at pH 8.2 shown the lowest thiobarbituric acid‐reactive substances (TBARS, 0.053 ± 0.003 nmol/ml) and pH changes (from 8.20 ± 0.01 to 8.18 ± 0.01), the highest fertilization rate (82 ± 3%). Undiluted and diluted spermatozoa at ratios of 1:2 and 1:9 with RPMI 1,640 media (pH 8.2, 9 and 10) and Cortland medium were inseminated with fresh eggs (Experiment 2). Spermatozoa in RPMI 1,640 medium at pH 9 (1:9) caused the lowest TBARS content (0.037 ± 0.002 nmol/ml) and pH changes (from 9.00 ± 0.01 to 8.98 ± 0.01), the highest fertilization rate (77 ± 2%) and motility parameters. Based on Experiments 1 and 2, eggs and spermatozoa were stored for another 3 days in RPMI 1,640 medium at pH 8.2 and 9 (1:9) respectively (Experiment 3). Fertilization rate of storage eggs and spermatozoa in Experiment 3 was 79 ± 5%, showing successfully storage of rainbow trout gametes with the same medium.     

Production of inbred larvae through self‐fertilization using oocytes and cryopreserved sperm from the same individuals after sex reversal in eastern oyster Crassostrea virginica

The eastern oyster Crassostrea virginica can change sex which makes self‐fertilization possible if sperm can be cryopreserved. In this study, small (~1 year old) and large (~2–3 years old) oysters were biopsied for sperm collection. Survival of the biopsied oysters after 1 year was 50% for small oysters and 17% for large oysters. Oocytes were collected from sex‐reversed females, and self‐fertilized with cryopreserved sperm. Of the 24 cryopreserved samples, 14 individuals had ≤1% fertility when crossed with oocytes from unrelated females, indicating that the cryopreserved sperm had reduced fertility. The other 10 individuals had a fertility of 39 ± 25% when crossed with oocytes from unrelated females (non‐selfing), but showed a significantly lower success of self‐fertilization (12 ± 16%) (P = 0.008), while aliquots of the same oocytes had a fertilization of 83 ± 11% when crossing with fresh sperm. Larvae were produced at day 3 in the self‐fertilized families (12–94% of the fertilized oocytes), and survived to eyed‐larvae stage at days 11–14. Genotyping with 9 microsatellite markers confirmed that the larvae resulted from self‐fertilization in four families. This study demonstrated the feasibility of creating self‐fertilized inbred lines of oysters by use of non‐lethal sperm collection and cryopreservation.     

疣吻沙蚕胚胎发育观察及盐度对其孵化的影响

采用显微镜观察了疣吻沙蚕(Tylorrhynchus heterochaeta)胚胎发育不同时期特征,并依据疣吻沙蚕人工孵化经验设置6个盐度梯度组(A:0,B:5,C:10,D:13,E:15,F:20),每组3个平行,研究了盐度对疣吻沙蚕受精率和孵化率的影响。结果表明,疣吻沙蚕胚胎发育可分为受精卵、卵裂期、囊胚期、原肠期、前担轮幼虫期、后担轮幼虫期、膜内三刚节疣足幼虫期和三刚节疣足幼虫期8个时期;盐度对疣吻沙蚕孵化影响显著(P0.05),C组受精率和孵化率最高,与其他组存在显著差异(P0.05)。适宜受精的盐度范围为10~13,最适孵化的盐度为10。     

贝类受精细胞学的研究现状

从成熟卵子的核相与体外促熟,精子的顶体反应,受精膜的形成,极体的释放与雌雄原核的形成以及多精入卵方面综述了贝类受精细胞学的研究成果,并展望了这一领域的研究和应用前景。     

Towards sustainable exhibits – application of an inorganic fertilization method in coral reef fish larviculture in an aquarium

Coral reef fish are collected from the wild and exhibited in aquaria worldwide. Some of the fish spawn in captivity; however, the eggs are usually neglected. In this study, we collected the eggs spawned naturally in the exhibit tanks, hatched and cultured them indoor in 2000‐L fibreglass tanks (initial density = 18 000 egg tank^?1). We applied an inorganic fertilization method commonly used in freshwater fish culture in raising these coral reef fish larvae. We maintained inorganic phosphorus concentration at 100 μg P L^?1 and inorganic nitrogen at 700 μg N L^?1 daily in the fertilized group (n = 4), while the control tanks (n = 4) were fed with rotifers (10 ind mL^?1). Chlorophyll a at particle sizes of both 0.45–20 μm and >20 μm, as well as NH₃‐N, NO₃‐N, and PO₄‐P concentrations were significantly higher in the fertilized group than the control. Zooplankton in the size groups of 10–50 μm (mainly flagellates) and 50–100 μm (mainly ciliates) were abundant (about 10~60 ind mL^?1) during 3–7 days in fertilized tanks. The average larval fish survival rate at 21 day after hatch in fertilized group was consistently higher than the control in two trials. The experiments demonstrated that the inorganic fertilization approach can be successfully adapted for coral reef fish culture in an aquarium to achieve sustainable exhibits.     

The effect of various nitrogen fertilization and foliar nutrition regimes on the concentrations of nitrates,ammonium ions,dry matter and N-total in carrot (Daucus carota L.) roots

Two field experiments (Experiment I in 2003–2005 and Experiment II in 2004–2005) with carrot c.v. ‘Kazan F₁’ were conducted at Trzciana village (50°06′N, 21°85′E). The experiments were arranged in a split-plot design with four replications. Two sub-blocks were identified in both experiments: I, without foliar nutrition; II, receiving plant foliar nutrition. The plants were sprayed three times alternately with: 2% urea solution, 1% solution of multi-component ‘Supervit R’ fertilizer (produced by Intermag, Poland) and again with 2% urea solution. Combinations with diversified nitrogen fertilization were distinguished within both sub-blocks. Experiment I comprised of: (1) Control, (2) Ca(NO₃)₂ 70, (3) Ca(NO₃)₂ 70 + 70, (4) (NH₄)₂SO₄ 70 and (5) (NH₄)₂SO₄ 70 + 70. Experiment II included: (1) Control, (2) ENTEC-26 35 + 35, (3) ENTEC-26 70 + 70, (4) ENTEC 26 105 + 105, (5) NH₄NO₃ 35 + 35, (6) NH₄NO₃ 70 + 70, (7) NH₄NO₃ 105 + 105. Where 70 kg N ha⁻¹ was used before sowing, whereas 35 + 35, 70 + 70 and 105 + 105 kg N ha⁻¹ were applied before sowing and as top dressing. Solid nitrogen fertilizer was added to the soil (produced by): Ca(NO₃)₂, Yara International ASA (Hydro); (NH₄)₂SO₄, Zak?ady Azotowe in Tarnów, Poland; NH₄NO₃, Zak?ady Azotowe in Pu?awy, Poland; and ENTEC-26, COMPO GmbH & Co. KG, Germany. The research aimed at determining the effect of diversified nitrogen fertilization and foliar nutrition on NO₃⁻, NH₄⁺, N-total and dry matter (d.m.) concentrations in carrot, and N uptake by storage roots. In Experiment I, nitrogen fertilization did not affect NO₃⁻ concentration, whereas in Experiment II, the applied N treatment increased NO₃⁻ concentration in carrot in relation to the control, except for the storage roots of plants fertilized with ENTEC-26 35 + 35. Nitrogen fertilization applied in both experiments caused a significant increase in N-total concentration in carrot and N uptake by storage roots in comparison with the control plants. In both experiments, nitrogen fertilization had a different effect on the concentrations of NH₄⁺ and d.m. in carrot. What is more, foliar nutrition treatments in both experiments had a different effect on the concentrations on NO₃⁻, N-total, d.m. in carrot and N uptake by carrot storage roots.     

滴灌条件下不同施钾量对甘蔗产质量的影响

为了评估甘蔗生产上应用滴灌施肥技术的效应,比较了滴灌系统及传统方法施用钾肥对甘蔗产量和品质的影响以甘蔗品种粤糖00—236为试材．进行了1年（2006～2007）露天盆栽滴灌种植试验。设置了4个通过滴灌系统施用的钾肥（KCl）水平,K1：10g／盆,K2：15g／盆,K3：20g／盆和K4：30g／盆,滴灌各处理施尿素15g／盆,和1个常规施肥方式（肥料施用量为尿素30g／盆和KCl30g／盆）。试验结果表明．滴灌施肥显著促进了甘蔗的生长．比常规施肥的甘蔗产量获得显著提高,K1、K2、K3和K4处理的每盆蔗茎收获量分别比常规管理的增加了19．2％、38．6％、45．9％和56．4％、滴灌条件下,施钾量不同对甘蔗产质量有显著影响．甘蔗产量随施钾量的增加而增加．但过多施用钾肥对甘蔗品质有负面影响.在甘蔗生产上应用滴灌施肥技术,可以节省钾肥的施用量。而且钾肥用量为常规推荐施用量的一半即可获得较常规施犯高三成以上的产量,通过滴灌系统施用钾肥既有经济效益．又有环境效益．     

Cryopreservation of silver barb Puntius gonionotus (Bleeker) spermatozoa: effect of extender composition,cryoprotective agents and freezing rate on their postthawing fertilization ability

The effects of extender composition, cryoprotectant concentration and freezing and thawing on the fertilization efficiency of cryopreserved spermatozoa of Puntius gonionotus were evaluated. Computer‐aided motility analysis of semen was conducted to check the suitability of spermatozoa for cryopreservation after mixing with different extenders and cryoprotective agents (CPAs). Extender‐4 with an osmolality 260 mOsmol kg⁻¹and pH 7.6 was used for the cryopreservation study. Among the CPAs, dimethyl sulphoxide (DMSO) was least toxic and more than 60% fertilization was achieved when used at 1.4 M at 0 °C for 10 and 30 min, whereas the toxicity of all CPAs to spermatozoa was evident when tested at 30 °C. Semen frozen at −16 °C min⁻¹ with 1.4 M DMSO showed 70% fertilization, which was significantly higher (P<0.05) than other freezing rates. Samples thawed at 35 °C water showed a fertilization rate comparable with that of fresh semen. Computer‐assisted semen analysis of fresh and frozen semen after thawing showed variations in different types of motility in spermatozoa and in their class. There was no significant difference in motility before or after cryopreservation; however, significant differences could be observed in the average path velocity (VAP), straight line velocity (VSL) and curve linear velocity (VCL). Semen of silver barb could be cryopreserved with extender‐4 by addition of 1.4 M DMSO to a final cryopreservation medium (MED 2) cooled at a rate of −16 °C min⁻¹, stored in liquid nitrogen (−196 °C) and utilized after thawing at 35±2 °C.