天然青杨种群性成熟条件及性别间差异

对小五台山地区青杨种群进行野外调查和数据分析研究,发现雌雄植株的性成熟条件具有差异。雌株性成熟的最小年龄(17 a)小于雄株(21 a),而雄株性成熟时的最小胸径和株高都大于雌株,不同性别的青杨其性成熟条件存在差异,雌株性成熟时间一般早于雄株,并且其成熟时的个体也小于雄株。     

Effects of chronic heat stress on the reproductive capacity of male Rex rabbits

The effects of chronic heat stress on the reproductive system of rabbits have not been thoroughly examined. Therefore, we investigated the effects of heat stress on the reproductive performance of male Rex rabbits and documented the recovery process after stress withdrawal. Thirty age-matched, male Rex rabbits were placed into artificial climate chambers and randomly divided into three groups: control, heat stress, and recovery. Our results indicate that both libido of rabbit and sperm density were decreased significantly during the 9 weeks exposure to heat stress. Semen volume was mildly affected. Histomorphological and TUNEL assay results showed that chronic heat treatment adversely affected microscopic structure of the testes, and elevated the apoptosis of germ cells in the seminiferous tubules distinctly. However, these adverse effects induced by heat were transient as all measured parameters returned to control levels following the recovery period.     

Experimental management of Mediterranean temporary pools for conservation of the rare quillwort Isoetes setacea

Mediterranean temporary pools represent unique species-rich habitats with many rare and endangered species. The Roque-Haute Natural Reserve is one of the few sites in France with Isoetes setacea Lam., a very rare Mediterranean quillwort, considered as a keystone species determining a priority habitat for the European Union. Land uses changes have favoured the invasion of the pools by several shrub and tree species (e.g., Ulmus minor, Fraxinus angustifolia subsp. oxycarpa). Clearing shrubs in an experimental area of one pool resulted in the increase of I. setacea as compared to control, combining a higher cover in previously occupied quadrats and more quadrats occupied. Litter accumulation had a negative effect on the population of Isoetes but this effect was detectable only in the cleared area. Light attenuation was shown experimentally to be detrimental to the vegetative and regenerative production of I. setacea. Clearing of the shrubs and removal of the litter led to an increase in the I. setacea populations and therefore appears to be an effective technique for restoring these plant communities invaded by shrubs. Long-term shrub control should be ensured by reintroducing sheep grazing in order to enhance the sustainable conservation of this oligotrophic habitat.     

鸡性分化前抑制雌激素合成对性行为和视前内侧核的影响

 在受精蛋孵化第3天从气室注入100 μl生理盐水或芳香化酶抑制剂(AI),出雏后常规饲养到8月龄性成熟,观察其性行为,检测血清性激素水平,观察下丘脑视前内侧核(POM)形态结构变化。结果发现,AI处理母鸡获得雄性交配行为,血中雌二醇(E2)和睾酮(T)含量发生变化,雄性交配频率与血清T/E2 比呈正相关。1日龄雌雄雏鸡POM细胞大小和形态无明显差异,AI处理后细胞均变大;性反转母鸡POM细胞形态较正常母鸡无明显变化,但细胞密度降低,细胞变小。结果表明,在胚胎期抑制芳香化酶活性可以引起血清性激素水平、性行为雄     

红麻新品种闽红31的选育与推广

闽红31系以红麻青皮3号为母本与722为父本杂交选育而成。1989～1998年与青皮3号复壮种对比41点次，平均亩产原麻427.5kg，比青皮3号增产16.68%，达极显著。与粤74/3原种对比51点次，平均亩产原麻423.8kg，比粤74/3增产13.62%，亦达极显著。该品种群体整齐、植株高大、茎粗、有效株数多，抗炭疽病力强，丰产稳产性好、适应性广。至2000年省内外累计示范推广0.7万hm^2。     

虎斑颈槽蛇肾脏存在两性差异

虎斑颈槽蛇 (Rhabdophistigrina)雌、雄性的肾脏在形态和结构上存在明显的差异 ,雌性虎斑槽蛇的肾脏呈暗红色且较细小 ,雄性的肾脏呈橙黄色且较粗壮 ;雄性肾脏具有明显肾性节(Sexualsegment) ,而雌性不具有此结构。     

Stallion-like Behavior in Mares: Review of Incidence, Characteristics, Ovarian Activity, and Role of Testosterone

Stallion-like sexual behavior in mares is rare, except in association with ovarian tumors or hormonal treatments. The rarity of the phenomenon was confirmed in a recent 3-year study. The mean number of mares with detected stallion-like behavior, including mounting with thrusts, during an entire ovulatory season was 5.7 (17/3 years) in a herd averaging 105 mares (5% incidence/mare/season). From a total of 17 mountings of an estrous mare by another mare, 15 occurred when the mounting mare was in the follicular phase and two when in the early luteal phase. Plasma testosterone concentration on the day of mounting was higher (P < 0.01) in the mounting mares (17.7 ± 2.3 pg/ml) than in the standing mares (10.9 ± 0.5 pg/ml). No other deviation in the endocrine, behavioral, or morphologic aspects of the estrous cycle was observed. In another study, testosterone was assayed daily from 7 days before to 4 days after ovulation in seven mares during estrous cycles with no detected mare-on-mare mountings. Concentrations during the follicular phase were highest on the days corresponding to when mare-on-mare mounting was detected in the previous study. It is concluded that the rare occurrence of stallion behavior by untreated mares with no detected ovarian tumors is a consequence of an unusually high, apparently transient fluctuation in circulating testosterone at the time of mounting.     

浅谈四川甘蔗有性杂交育种

四川甘蔗有性杂交育种工作是在正确选配亲本基础上，即选择含有热带种、热带割手密、印度割手密（野生种）的血缘，经过该３个种分别杂交的Ｆ＿３～Ｆ＿６代，进行精细培育单株、多次区域化试验、示范栽培及繁殖推广等，建立起一整套的科学育种程序，培育出川蔗系列新品种２０个，促进了四川蔗糖生产的发展。     

体外无血清培养牛垂体细胞分泌催乳素的调节—性腺激素的作用

本实验对牛垂体混合细胞进行24小时体外无血清培养,对其分泌催乳素的功能进行了观察,并分别在培养介质中加入0、1、10、100ng/ml的孕酮、脱氢表雄酮、雄烯二酮、雌二醇和睾酮,用放射免疫测定法测定培养液介质中催乳素含量,以研究这些性腺激素和中间产物对垂体细胞分泌催乳素的影响。结果表明:孕酮对离体牛垂体细胞无血清培养条件下分泌催乳素的功能没有影响。而脱氢表雄酮、雄烯二酮、睾酮和雌激素均引起催乳素分泌量显著升高,说明这些性腺类固醇激素对牛垂体细胞离体培养分泌催乳素具有促进作用,可能是垂体前叶催乳素分泌调节的重要组成部分。