水霉属菌(Saprolegnia)分离培养技术研究

 对水霉(Saprolegnia)的分离培养技术进行了探索,筛选出大麻籽、油菜籽、红花籽、苍蝇、蚜虫、小麦粒、玉米片、茶叶、葵花仁9种材料作为诱发水霉菌的诱饵。其中油菜籽能防止腐霉菌(Pythium)污染,是初步纯化菌种、排除杂菌的适宜饵料。同时发现控制温度能使水霉在最短时间内分别产生无性或有性繁殖。在水培条件下,25℃左右适合菌丝及无性器官的发育,有性器官却不能产生,而只有在15~17℃条件下才能使水霉很快进入有性生殖阶段;在加入200mg/L链霉素的CMA培养基上促发有性阶段则需要在25℃左右的温度下进行,方能缩短培养时间。     

金定鸭的性双态分化和性行为发育

金定鸭的外型分化，受自然选择和性选择的双重影响。在生长发育过程中，依羽域在适应水域环境的重要性，雌雄金定鸭的正羽都按共同的羽域顺序陆续更换生长；与此同时，一日龄外型相同的异性雏鸭，逐渐表现出性双态，包括喙色、羽色、声音、性羽、体重和行为的表型差异，以满足繁殖竞争的需要。金定鸭性行为的出现以其性双态分化为基础，而性行为的分化又是其生理成熟的前提条件。对雄鸭的观察分析结果表明，性双态分化和性行为发育速度的快慢与其生理成熟的早迟是一致的。黑色尾羽的雄鸭，体重较小，其发育速度和性成熟均快于体重较大的白喙或端白尾羽者，因此，建议将尾羽颜色、性双态分化和性行为发育速度作为雄鸭的选育指标。     

性引诱剂用于蔬菜害虫的预测预报和发生规律研究

小菜蛾、斜纹夜蛾、甜菜夜蛾是蔬菜上的重要害虫，应用三种性引诱剂预测预报三虫，具有灵敏高度、高峰清晰、规律清楚、省工省时等特点。     

松嫩平原碱化草甸朝鲜碱茅种群生殖特性的定量分析

通过对朝鲜碱茅单化群落独立株丛的大样本取样和对正常花序随机取样的调查与测定，定量分析了松嫩平原碱化草甸朝鲜碱茅种群的生殖特性。朝鲜碱茅种群话营养繁殖数量性状之间有较强的规律性。丛分蘖数、丛地上生物量、丛生殖枝数和丛生殖技重分别与丛径之间，以及丛生殖枝重与丛生殖枝数之间均为线性正相关，丛生物量随着丛分蘖数的增加呈幂函数增加。朝鲜碱茅种群在整个生殖生长发育过程中具有较强的有序性。圆锥花序各节位上的小穗数量呈伽玛分布。各节位上的小花数量随着节位的增高呈Logistic曲线形式减少。小穗数和小花数均随着节位的增加呈y＝ae(－b／x)饱和型指数曲线形式累积增长。     

Serum levels of reproductive steroid hormones in captive sand tiger sharks, <Emphasis Type="Italic">Carcharias</Emphasis><Emphasis Type="Italic">taurus</Emphasis> (Rafinesque), and comments on their relation to sexual conflicts

Levels of reproductively-related steroids were determined in captive male sand tiger sharks, Carcharias taurus, maintained at two institutions: SeaWorld Adventure Park Orlando and the National Aquarium in Baltimore. Sexual conflicts were absent at the former, but were documented at the latter. Serum titers of 17β-estradiol, progesterone, testosterone, and 5α-dihydrotestosterone were determined via radioimmunoassay in adult male sharks from 1988 to 2000. Sampling overlap between the two institutions occurred for 3 months of the year, but steroid concentrations were compared only for April due to the occurrence of sexual conflicts in the sharks at the National Aquarium in Baltimore in that month. For April, testosterone and dihydrotestosterone were significantly higher in the SeaWorld males, and progesterone was significantly higher in the National Aquarium in Baltimore males, while estradiol was not significantly different. Steroid levels were also determined from serial samples taken monthly over 17 months from three male sharks and one female shark at the National Aquarium in Baltimore in 2001–2002 and were compared with corresponding observed sexual conflicts. The steroid levels obtained showed distinct annual hormonal cycles in the male sharks and corroborated a biennial cycle for the single serially-sampled female shark. Furthermore, the steroid levels for individual males correlated with sexual conflicts as well as their position within the male dominance hierarchy. As this species is depleted in some regions globally, insight into the steroid profile of mature sand tiger sharks is important for a greater understanding of the relationship between their reproductive physiology and behavior, and may aid in captive management and reproduction. L. E. L. Rasmussen—Deceased.     

Sexual dimorphism of fast muscle fibre recruitment in farmed Atlantic halibut (Hippoglossus hippoglossus L.)

Commercially farmed Atlantic halibut (Hippoglossus hippoglossus) were reared at the Aga Marin's facility located on Dønna (Norway) under ambient environmental conditions in duplicate 15 × 15 × 8 m netpens (May 2004 to May 2005). Twenty fish were sampled five times over a twelve month production period during which time the average body weight increased from 1.26 to 2.08 kg (n = 100 fish). Body mass, fork length (L_F), and the number and size distributions of fast muscle fibres were determined in male and female fish. All males matured during the autumn whereas no maturation was observed in females. From the point of maturation females had superior growth performance to males and body mass and the total cross-sectional area of muscle were 1.4-fold (P < 0.05) and 1.3-fold higher (P < 0.01) respectively by May 2005. The total number of fast muscle fibres per trunk cross-section at 0.55 L_F was 24.5% higher in females (7.58 × 10⁵) than males (5.80 × 10⁵) prior to sexual maturation. In females, muscle fibre recruitment slowed with short days and low water temperatures (< 6.5 °C), but had increased to 1.01 × 10⁶ by May 2005 (P < 0.001). In contrast, there was no growth and no increase in muscle fibre number in males following the onset of maturation. The distribution of muscle fibre diameters prior to maturation in males was also significantly different between male and female fish matched for L_F. The results illustrate a sexual dimorphism of muscle fibre recruitment patterns in Atlantic halibut and highlight the adverse affects of sexual maturation in males on muscle growth.     

Off-Season Spawning of Eurasian Perch Perca Fluviatilis

This study was designed to determine the effects of the selection for body weight and of two final warming durations during an out-of-season reproductive cycle on gonad recrudescence, plasma steroid levels and spawning in Eurasian perch Perca fluviatilis males and females. Two different bodyweight classes (200–250 and 350–400 g) and two different warming periods (1 or 2 months) were studied.At the end of the chilling period, a significant effect of the selection for body weight was observed on gonad development whereas fish were the same age. According to higher levels in testosterone (12 ng mL^–1), a better development was recorded for smaller breeders (P < 0.05). A short water warming period up to 14°C (1 month v.s. 2 months) allowed higher rates of females with completed gonadogenesis (33–38% v.s. 7–8%) and spawning (31–33% v.s. 0%) (P < 0.05). Spontaneous out-of-season spawning (17 ribbons) and larvae were obtained. Relative fecundity was about 100 eggs g^–1 of female body weight. Five ribbons were partly fertilized with a rate ranging from 5 to 90%. These studies have shown that delayed spawning in Eurasian perch can be obtained by a temperature manipulation, but results are not sufficient because of low stimulation rate of females, low spawning rates and high heteroge-neity of fertilization rates. The effects of other environmental factors like photoperiod should be tested in further experiment to improve the protocol inducing out-of-season spawning production.     

Sexual behaviour of yearling Awassi,Charollais × Awassi and Romanov × Awassi rams exposed to oestrousAwassi ewes

This study was conducted to evaluate the sexual performance of 10-month-old, ram lambs of different breed groups. Eight ram lambs each of Awassi (A), F₁ Charollais × Awassi (CA) and F₁ Romanov × Awassi (RA) breed types were subjected to sexual performance tests by being individually exposed to two oestrous Awassi ewe lambs for four 20-min periods. Bouts of leg kicking and anogenital sniffing were similar among breed groups. Mounting frequency was greater (p < 0.05) in RA than in A and CA ram lambs. Tail-raising was greater (p < 0.05) and mating rate tended to be greater (p < 0.10) in A than in RA and CA ram lambs. The number of mounts per tail-raising (efficiency) was influenced by breed group and test day (p < 0.05). Awassi ram lambs maintained the best efficiency throughout the experiment. Efficiency in RA and CA ram lambs improved with each test day. Results of the present study indicate that RA ram lambs have greater mounting frequency than A and CA, while Awassi are more capable of mating with fat-tailed females than the CA and RA ram lambs.     

温度湿度及种球茎大小对花魔芋有性繁殖的影响

有性繁殖是促进魔芋种植业发展和品种改良的有效途径，引起了极大的兴趣。本文研究117个花魔芋（Amorphophallus konjac K. Coch)单株花粉成熟后连续5d的温度、湿度以及花芽种球茎对其有性繁殖的影响，结果表明：授粉期间的温度和湿度对其自花授粉结实影响大，结实株花粉成熟后连续5d的平均温度和湿度分别为24℃和64%，均显著高于不实株，高温高湿有利于散粉和花粉的萌发从而完成受精；花芽种球茎大小对有性繁殖也有影响，结实株平均种球茎重显著高于不实株，且与单株结实浆果数呈极显著的正相关（r=0.6096, N=29），因此，宜选用花芽球茎大的用于魔芋有性繁殖。     

抗除草剂转基因油菜向杂草诸葛菜的潜在基因漂移

以抗除草剂草甘膦和草丁膦转基因油菜为父本 ,诸葛菜为母本 ,在人工授粉条件下研究抗性基因向诸葛菜的潜在基因漂移。采用荧光显微镜观察转基因油菜花粉在诸葛菜柱头上的萌发生长情况 ,并与诸葛菜自花授粉的情况进行比较。结果显示 2种转基因油菜花粉在诸葛菜柱头上的萌发生长情况类似。花粉粘合的数量比自交时显著减少 ,出现粘合延迟现象 ;花粉在柱头上不能正常萌发生长 ,有的呈现明显的畸形 ,花粉管不能穿过乳突细胞 ,更不能进入花柱和胚囊发生受精 ,这些结果表明两者的亲和性较差。授转基因油菜的花粉后诸葛菜不能结实也进一步证明了两者的亲和性较差。上述结果表明抗除草剂转基因油菜的抗性基因向诸葛菜漂移的可能性较小。