Preliminary observations on the feeding, habits and reproduction biology of Gymnarchus niloticus from Lake Chad

The preliminary results obtained from the study of stomach contents of specimens of Gymnarchus niloticus of a size ranging from 56 cm (66 grams) to 152 cm (12.0 kg.) from August to December, 1982 indicate for these sizes an exclusively piscivorous diet. The predominant prey species in Lake Chad are Tilapia/Sarotherodon , and Clarias . The prey is often cut in two parts before it is swallowed. Small prey may be swallowed whole. The implication of this prey capture method on prey-predator relationship and therefore the impact of the predator is discussed. The breeding season of Gymnarchus niloticus in Lake Chad has been deduced from observation of changes in gonad maturity stages and the results indicate that breeding takes place between August and November. Data are also presented on the fecundity, size of ripe eggs and probable size at maturity

Reproductive biology of the rock shrimp Sicyonia dorsalis (Decapoda: Penaeoidea) from the southeastern coast of Brazil

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Sugar Feeding Affects the Male Contribution in Reproduction in Aedes Aegypti

Juvenile hormone (JH) is crucial for the stimulation and progression of oogenesis from emergence to the previtellogenic resting stage in female Aedes aegypti mosquitoes. Juvenile hormone has been suggested to be among the many substances transferred form the male accessory glands to the female during copulation but no evidence for this has previously been provided. Quantification of JH III in the accessory glands of males and in the bursae copulatrix and spermathecae of mated females was performed using HPLC-FD. These amounts were measured in relation to the quality of adult sugar feeding in the male. The effect of this variable transfer was measured on two fecundity markers that occur during the previtellogenic stage of oogenesis, specifically follicular resorption and ovarian lipids. Male mosquitoes provided with 20% sucrose contained ~ 60% greater amount of JH in the accessory glands and transferred 4 fmol more JH during copulation than males provided with 3% sucrose. These differences resulted in a nearly 40% reduction in follicular resorption and an approximate 3-fold increase in lipid content in the ovaries of mated females during the previtellogenic stage. These results suggest that the contribution of JH from the male is dependent on the quality of nutrition obtained during adult sugar feeding. Female fecundity is likely responsive to these variable previtellogenic effects, possibly resulting in a difference in the number of eggs laid. Improvements in female reproductive output may have wider implications in the transmission of diseases attributed to this important arbovirus vector.

10 Jahre Untersuchungen zur Reproduktionsbiologie des Dorsches im Institut für Ostseefischerei

The reproduction biology of cod is one of the main re-search topics of the Institute of Baltic Sea Fisheries at Rostock. It was defined 10 years ago when the Institute was formed. Since then results have been published in a number of publications. This paper summarizes the main results of the past decade ant outlines necessities for future research in cod reproduction biology in the Baltic Sea.

Welche Faktoren beeinflussen die Stärke der Dorsch-Jahresklassen?

In the previous years extensive investigations were carried out concerning the reproduction biology of cod in the Baltic Sea. The analyses showed that the year class strength of the eastern Baltic cod stock is decisively determined by the bad oxygen conditions during the spawning season in the summer and by sprat as predator of the cod eggs. In the western Baltic Sea these factors have no importance. The year classes are mainly determined by the strong variations of the portions of female cods, which participated in the spawning activities in the region. The individuals within the length range from 35 cm to 45 cm have a special importance at this time, caused by the actual age structure of the cod stock.

Untersuchungen zur Aufzucht von Dorschen (Gadus morhua morhua) der Westlichen Ostsee. Teil II: Aufbau und Hälterung eines Laichfischbestandes sowie Erbrütung der gewonnenen Eier

In 1993 and 1994 hatching and rearing of cod eggs and larvae from the western stock was carried out aiming at data about the reproduction biology of this species. This paper describes the hatching methods and first results of the correlation between various biotic and abiotic factors, naturally fertilized eggs from a broodstock, and the amount of viable larvae.

羊草生殖生物学研究

羊草 (Leymus chinensis (Trin.) Tzvel. ) ，隶属禾本科赖草属，是欧亚大陆草原区东部的重要草原建群种之一。羊草是牧草之王，属于我国有比较优势的战略性生物资源，对我国北方畜牧业发展以及保护生态环境均具有重要作用。 羊草较弱的有性生殖特性限制了其应用，本文从实验生物学角度，研究了羊草有性生殖的基本特点，并试图通过现代分子生物学手段探讨自交不亲和性的有关机理。本论文的主要结果如下： 1. 实验发现羊草具有自交不亲和性。以6 个羊草居群为材料，测定得知开放授粉时的结实率在6.5% - 56.7%之间，自交时结实率为0.6% - 4.3%，差异极其显著; FDA 染色法检测结果显示羊草成熟花药中有活性的花粉达到92.2% 以上;在发育时间顺序和空间结构上，羊草雌蕊、雄蕊适于异花和自花授粉;花粉柱头亲和性实验表明，自交花粉只有5.5%-11.7% 是亲和的，杂交花粉亲和率达到了60.0%-84.8%，说明自交花粉在柱头上萌发受到抑制，其次，荧光显微镜还观察到“不亲和花粉”在进入柱头后生长缓慢，或停止延伸。 2. 初步确定羊草自交不亲和性具有配子体型遗传特点。以不同居群羊草杂交后的姊妹系作为实验材料，观察到自交组合的亲和率变幅为0 % - 6.9 %，杂交组合的亲和率具有连续性变异和变幅较宽的特点（47.5％ - 96.0 %），且正反交结果具有一定的一致性（88.2％），表现出配子体遗传特性。 3. 羊草居群内结实率存在一定变异。以羊草单株为单位分别进行自交、随机互交和开放授粉，结果显示三者的平均结实率分别为4.6%，18.1% 和35.7%，株间的变异系数分别为33.4%，21.2%和17.1%，这些株间的变异均达到统计上的显著差异;同时羊草自交、杂交和开放授粉之间具有一定的相关性，显示羊草的这种株间差异与株系本身的生理特性相关。 4. 分离了羊草硫氧化还原蛋白 H 基因(ThioLc)并对其功能进行了分析。克隆了ThioLc全长和cDNA序列。序列分析结果显示，DNA全长2257 bp，包括3 个内含子和4 个外显子，与水稻Thio h 的cDNA 序列相比，具有 32.0% 的同源性;Southern 杂交显示 ThioLc 在羊草基因组中是单拷贝;Northern 杂交显示 ThioLc 在羊草根、茎、叶和幼小的雌蕊中没有表达, 在成熟雌蕊和幼小的花粉中微量表达, 在成熟花粉中大量表达，说明分离的羊草硫氧化还原蛋白H 基因具有花粉特异表达特点。 5. 原核表达的ThioLc 蛋白具有较高的催化活性。构建了ThioLc 基因的原核表达载体，检测证明ThioLc基因在大肠杆菌中正常表达;提取表达蛋白，纯化，用胰岛素和二硫苏糖醇反应体系进行硫氧化还原蛋白的催化作用反应，结果表明表达的蛋白具有催化活性。这一结果为进一步搜寻靶向蛋白和研究该蛋白的结构、功能和作用方式奠定了基础。

Aquatic resource conservation - The first Yangtze finless porpoise successfully born in captivity

Background. As the sole freshwater subspecies of finless porpoise (Neophocaena phocaenoides), the Yangtze finless porpoise (N. p. asiaeorientalis) lives only in the middle and lower reaches of the Yangtze River and its appended Poyang and Dongting Lakes. As a result of human activity on the river, including over and illegal fishing, pollution, transportation and dam construction, the population of Yangtze finless porpoises has been steadily and rapidly decreasing during the past several decades, which leads the animal to be endangered. Methods. For saving this unique animal from extinction, three corresponding measures, in situ conservation, ex situ conservation, and intensifying breeding research in captivity, were proposed and have been implemented since the 1980s. Results. After successfully rearing the animals in captivity for almost nine years, the first Yangtze finless porpoise was successfully born in captivity on July 5, 2005. The calf is male, with a body length of 69 cm. This is the first freshwater cetacean ever born in captivity. Conclusion. The successful birth of this calf confirms that it is possible to breed the Yangtze finless porpoise in captivity. Furthermore, this will greatly benefit the conservation efforts, and also greatly bolster our on-going efforts to study the reproductive biology of these animals. Recommendation. More studies and efforts are expected to establish a sustainable, captive colony of the Yangtze finless porpoise, which will not only greatly expand our knowledge about the reproduction biology of this animal, but also help to redeem the wild population through a careful yearly 'soft releasing' process.

鼠尾藻的生理生态和繁殖生物学研究

鼠尾藻 [Sargassum thunbergii (Mert.) O’Kunte] 是北太平洋西部特有的一种暖温性大型经济褐藻，在我国沿海地区北起辽东半岛南至雷州半岛的硇州岛，都有广泛分布。鼠尾藻在食品和医药领域的应用开发在我国有悠久历史。近年来，随着水产动物养殖业迅速发展，其应用领域得到了进一步拓展，发现鼠尾藻是海参、鲍鱼等水产动物的优质天然饵料。 受海参和鲍鱼产业发展影响，鼠尾藻的市场需求量成倍增加。目前鼠尾藻的供应全部依赖自然资源。掠夺式的采收方式导致鼠尾藻的野生资源遭到了很大破坏，种群规模和数量不断减小，生态环境也发生了变化。近年来鼠尾藻供需矛盾已经非常突出，如何保护和有效利用该海藻资源已经成为海藻科研和产业界的一个重要话题。 以往对鼠尾藻的生态学和人工育苗技术方面的比较深入的研究工作很少，许多基础科学问题研究不够，人工繁殖技术没有很好地掌握，已经不能满足产业发展需求并限制了鼠尾藻应用价值的发挥。为此，有必要系统性研究鼠尾藻原生态环境、野生状态下生长发育的年际交替规律、鼠尾藻有性生殖过程、人工育苗方法途径、鼠尾藻吸收无机营养能力、以及在调控藻际菌群能力等基础科学技术问题，带动鼠尾藻饵料规模的良性健康扩大，并进一步推动海参和鲍鱼等水产业的发展。 本文以青岛汇泉角的鼠尾藻为基本实验材料，通过野外实地周年观察并结合实验室工作，对上述问题初步进行了初步探索，主要获得如下结果： （1）在青岛地区海滨岩石地带，全年都可观察到鼠尾藻藻体，藻体的形态大小和生理发育状况随季节变化表现出很大的差别性。夏季藻体黄褐色，初生分枝伸展，有次生分枝、生殖枝和气囊的发育，而冬季的藻体黑褐色，初生分枝粗短，没有次生分枝、生殖枝和气囊的发育。6月鼠尾藻出现有性生殖器官生殖托，到7月生殖托发育成熟，7月藻体最长，平均在50厘米左右，11月可观察到有性生殖和假根产生的幼苗。假根营养繁殖再生苗是鼠尾藻种群新苗源的主体，在维持种群自然繁衍和发展中起主导作用。 （2）有性生殖过程是鼠尾藻个体发育的大事件，精卵结合产生幼苗的潜力巨大，是开展未来规模化人工育苗的希望依托。鼠尾藻初生分枝长度和外形株间差异较大，每株鼠尾藻平均大约有20个初生分枝，约一半初生分枝可发育成熟，充分发育的初生分枝可产生30－50个次生分枝，每个次生分枝上又有大约20－30个生殖枝，每个生殖枝上生殖托数量一般为1－3个，雌托长度大多在3－5mm，雄托长度在10－15mm。生殖托的成熟度由基部向顶端递减。一个雌托排卵量平均为400多粒。以此计算，每株雌性鼠尾藻在生殖季节可产生200多万个卵。 卵从生殖窝孔排出后粘附于雌托表面，雄托排精时间稍晚于雌托挂卵时间，精子游动到卵周围与之结合完成受精过程。受精卵大约在受精后1小时分裂为两个大小相近的细胞，2小时后再进行第二次分裂，其中一个细胞横裂为两个细胞：一个细胞较大，另一个细胞较小，另一个细胞的分裂面与第一次分裂垂直，等分为两个细胞，随后细胞不断分裂。在受精后48小时左右，胚苗一端产生出假根。胚苗从雌托脱落的第一周内，尽管细胞数量增加较快，但新细胞体积减小，使得胚苗的体积增加不多。从第二周开始幼苗的体积出现明显的增加。此时，无机营养盐的有效补充对鼠尾藻幼苗培养长大是十分必要的。下海后的管理是保障幼苗成活的关键，此时常常发生脱苗现象。 （3）鼠尾藻对无机氮、磷都有较强的吸收能力，鼠尾藻从海水中吸收无机氮和无机磷的能力分别为75.1mg/kg/day和36.2mg/kg/day，鼠尾藻对氮、磷吸收的质量浓度比例接近5：1。 （4）鼠尾藻具有调节藻际微生物种群的能力，鼠尾藻对弧菌和总异养菌菌群都有一定程度的抑制作用，研究发现鼠尾藻抑制弧菌的能力存在种的差异，其中对鳗弧菌65#显示的抑制作用最强，鼠尾藻的抑菌能力的强弱还与其生理状态的好坏有显著关系。 通过上述研究结果，我们认为：鼠尾藻通过有性生殖过程培育种苗在理论上具有可行性，发展潜力很大。而解决幼苗后期培养中的脱苗问题、提高苗的成活率是下一步需要研究攻克的关键技术；假根营养繁殖再生苗源是维持该藻自然种群的主要方式，也是目前开展人工养殖获得健壮苗种的重要途径，连根采收方式对鼠尾藻野生资源破坏严重；建议野生鼠尾藻在7月底到8月初（水温27℃左右）采收（此时藻体生物量接近最大、并完成生殖过程），采用剪切方式保留假根和幼小的初生枝收获，该方式还可以应用到收获人工筏式养殖的鼠尾藻中，这对保证假根的完整性，大量获得下一个栽培季节的健壮新苗有实际意义；建议进一步开发鼠尾藻吸收富营养化物质、净化养殖环境水质的能力，以及对弧菌和总异养菌的抑制能力，建立海参、鲍鱼和鼠尾藻生态互补、环境友好的养殖模式，控制病害发生，提高水产品产量和质量。

L'oviparisme en la família Scorpaenidae (Pisces: Scorpaeniformes)

En aquest treball de tesi doctoral es descriu l'estructura gonadal, gametogènesi i cicle anual de Scorpaena porcus, S. scrofa i S. elongata per tal d'aprofundir en el coneixement dels diferents graus d'especialització dins l'oviparisme en peixos. Es pretén fer èmfasi en aquells trets inusuals que difereixen del què s'ha descrit fins ara per la majoria de les espècies ovípares de teleostis, i relacionar-los amb l'estratègia reproductiva de les espècies que els presenten El mostreig s'ha dut a terme de forma intensiva entre l'any 2000 i 2002, tot i que s'ha continuat recol·lectant mostres fins a l'agost de 2004, amb més o menys freqüència segons la necessitat. En total s'han obtingut 258 exemplars de S. porcus, 119 de S. scrofa i 46 de S. elongata. S'ha pogut veure com S. porcus, S. scrofa i S. elongata són espècies ovípares ovulípares especialitzades, ja que la seva estructura ovàrica presenta tot una sèrie de trets molt particulars i poc comuns a la resta de peixos ovípars estudiats fins ara: posició central del raquis musculo-connectiu que es troba envoltat completament pel lumen i la paret ovàrica; presència de peduncles en oòcits en fase de creixement secundari; escassetat i mida petita dels alvèols corticals; poc gruix de la zona radiata; i secreció d'una massa gelatinosa que engloba els ous en el moment de la posta. Totes aquestes característiques també s'han observat en Scorpaena notata, suggerint que l'especialització de l'oviparisme ovulípar es dóna en tot el gènere Scorpaena. L'estructura testicular i l'espermatogènesi d'aquestes espècies també és força particular. Per una banda els testicles són del tipus lobular no-restringit, tot i que presenten algunes característiques com la ordenació parcial dels cists segons l'estadi de maduració de les cèl·lules germinals que contenen i l'absència de lumen central, que actualment només s'ha observat en testicles del tipus lobular restringit de les espècies de la sèrie Aterinomorpha. Per l'altre banda, l'espermatogènesi és del tipus semicística, és a dir, els cists s'obren abans d'acabar tot el procés i les cèl·lules germinals s'acaben de desenvolupar a la llum del lòbul fins a espermatozoides. La posta d'aquestes espècies és múltipla i constisteix en una massa gelatinosa d'ous pelàgica, que en el cas de S. porcus s'alliberen entre els mesos de juny i agost, i en S. scrofa, a partir del mes de juliol. S'ha relacionat la presència d'aquesta massa amb un aparellament mascle-femella, de manera que el mascle alliberaria l'esperma directament sobre la massa d'ous, assegurant així la fartilització total dels mateixos.

Loss of Methylation at H19 DMD Is Associated with Biallelic Expression and Reduced Development in Cattle Derived by Somatic Cell Nuclear Transfer

Although cloning of mammals has been achieved successfully, the percentage of live offspring is very low because of reduced fetal size and fewer implantation sites. Recent studies have attributed such pathological conditions to abnormal reprogramming of the donor cell used for cloning. The inability of the oocyte to fully restore the differentiated status of a somatic cell to its pluripotent and undifferentiated state is normally evidenced by aberrant DNA methylation patterns established throughout the genome during development to blastocyst. These aberrant methylation patterns are associated with abnormal expression of imprinted genes, which among other genes are essential for normal embryo development and gestation. We hypothesized that embryo loss and low implantation rates in cattle derived by somatic cell nuclear transfer (SCNT) are caused by abnormal epigenetic reprogramming of imprinted genes. To verify our hypothesis, we analyzed the parental expression and the differentially methylated domain (DMD) methylation status of the H19 gene. Using a parental-specific analysis, we confirmed for the first time that H19 biallelic expression is tightly associated with a severe demethylation of the paternal H19 DMD in SCNT embryos, suggesting that these epigenetic anomalies to the H19 locus could be directly responsible for the reduced size and low implantation rates of cloned embryos in cattle.

Embryo Mitochondrial DNA Depletion Is Reversed During Early Embryogenesis in Cattle

The extensive replication of mitochondria during oogenesis and the wide variability in mitochondrial DNA ( mtDNA) copy numbers present in fully grown oocytes indicate that mtDNA amount may play an important role during early embryogenesis. Using bovine oocytes derived from follicles of different sizes to study the influence of mtDNA content on development, we showed that oocytes obtained from small follicles, known to be less competent in developing into blastocysts, contain less mtDNA than those originating from larger follicles. However, because of the high variability in copy number, a more accurate approach was examined in which parthenogenetic one-cell embryos were biopsied to measure their mtDNA content and then cultured to assess development capacity. Contrasting with previous findings, mtDNA copy number in biopsies was not different between competent and incompetent embryos, indicating that mtDNA content is not related to early developmental competence. To further examine the importance of mtDNA on development, one-cell embryos were partially depleted of their mtDNA (64% +/- 4.1% less) by centrifugation followed by the removal of the mitochondrial-enriched cytoplasmic fraction. Surprisingly, depleted embryos developed normally into blastocysts, which contained mtDNA copy numbers similar to nonmanipulated controls. Development in depleted embryos was accompanied by an increase in the expression of genes (TFAM and NRF1) controlling mtDNA replication and transcription, indicating an intrinsic ability to restore the content of mtDNA at the blastocyst stage. Therefore, we concluded that competent bovine embryos are able to regulate their mtDNA content at the blastocyst stage regardless of the copy numbers accumulated during oogenesis.