不同养分条件下喀斯特适生物种植物间相互作用诱导的形态可塑性

研究非生物环境条件如何影响植物间相互作用及其诱导的形态可塑性,有利于揭示喀斯特适生植物物种同时应对多种环境因素变异的策略。本研究以鬼针草(Bidens pilosa)和大叶醉鱼草(Buddleja davidii)为对象,分别在养分施加和不施加两种处理下,对植物进行单独生长(对照)、种内和种间相互作用3种处理,探讨养分可用性对种内、种间相互作用诱导的生物量和形态特征可塑性的影响。结果表明：不加养分处理中,鬼针草和大叶醉鱼草种内相互作用下的总生物量分别减少9.2%和14.4%,主要导致竞争效应,种间竞争不显著;加养分处理中种内促进作用占主导,二者分别增加35.1%和41.3%,大叶醉鱼草表现为种间促进作用,增加34.6%,鬼针草不显著。与对照相比,种内相互作用不加养分处理降低大叶醉鱼草根生物量和鬼针草的叶生物量,养分增加时提高大叶醉鱼草茎生物量,降低鬼针草比叶面积;种间相互作用不加养分处理提高大叶醉鱼草根冠比等特征,降低茎、叶生物量,增加鬼针草的茎生物量并减少其根生物量,加养时提高大叶醉鱼草根冠比和根生物量以及鬼针草的地径。这些结果说明,非生物环境条件可以通过影响种内与种间相互作用的强度...     

The Detection of Peaks in Luteinizing Hormone Secretion

Fluctations in luteinizing hormone are believed to consist of irregularly spaced sharp increases separated by periods of exponential decay. A simple method is presented for analysing such fluctuations when the data consist of uniformly sampled observations of hormone. Specific allowance for the exponential decay in the absence of pulses is made via a time series model before assessing the number and extent of pulses. All calculations are done using MINITAB regression programs. The results have been compared with those obtained by three established models and are in general agreement.     

The Detection of Peaks in Luteinizing Hormone Secretion

Fluctations in luteinizing hormone are believed to consist of irregularly spaced sharp increases separated by periods of exponential decay. A simple method is presented for analysing such fluctuations when the data consist of uniformly sampled observations of hormone. Specific allowance for the exponential decay in the absence of pulses is made via a time series model before assessing the number and extent of pulses. All calculations are done using MINITAB regression programs. The results have been compared with those obtained by three established models and are in general agreement.     

幼龄红嘴相思鸟小脑皮质组织学结构

为了探讨不同日龄幼龄红嘴相思鸟(Leiothrix lutea)小脑皮质的组织学结构变化,分别以1、5、9日龄红嘴相思鸟为研究对象,通过H.E和甲苯胺蓝法进行染色,光镜下观察红嘴相思鸟小脑冠状切面的显微结构。结果显示,1日龄时,小脑皮层由外颗粒层(EGL)、浦肯野细胞层(PCL)和内颗粒层(IGL)3层构成,外颗粒层较厚且清晰,而浦肯野细胞层和内颗粒层界限不清楚;5日龄和9日龄时,小脑皮质均可见外颗粒层、分子层(ML)、浦肯野细胞层和内颗粒层4层结构。对3个日龄红嘴相思鸟小脑皮质各层厚度进行单因素方差分析,随日龄增长,小脑皮质、分子层和内颗粒层厚度极显著增厚(P0.01),浦肯野细胞体积也极显著增加(P0.01);外颗粒层厚度变化不明显(P0.05),呈现先增厚后变薄的趋势,与皮质厚度的比例逐渐减小。研究表明,幼龄红嘴相思鸟在出生后,随日龄增长,小脑皮质层逐渐发育成熟。内颗粒层与外颗粒层的相对变化规律表明,内颗粒层细胞是由外颗粒层迁移而来的。     

多巴胺能药物对虎纹蛙GnRH和LH分泌活动的影响

利用在体注射实验和放射免疫测定法,研究了多巴胺能药物对性腺处于再发育期虎纹蛙的促性腺激素释放激素（GnRH)及促黄体激素（LH)分泌活动的影响。结果是：多巴胺（DA）及其激素剂阿扑吗啡（APO）可显著降低血浆LH水平;而多巴胺的拮抗剂－地欧酮（DOM）可显著增加垂体LH含量。DA对脑中cGnRH-Ⅱ的合成有抑制作用,而OM对其mGnRH的释放有一定的刺激作用。结果表明：DA可在脑及垂体水平分别抑制虎纹蛙GnRH和LH的释放,DA对LH释放的抑制作用很可能是通过D2受体实现的。     

The Secretion of Luteinizing Hormone in Ewes of Finnish Landrace During Estrus

The secretion of luteinizing hormone in ewes of Finnish Landrace during estrus. Acta vet. scand. 1979, 20, 216–223. — Luteinizing hormone immunoreactivity was measured in the venous plasma of four cycling Finnish Landrace sheep during the breeding season in connection with one synchronized estrus and the subsequent one. The ewes were slaughtered after the second estrus to establish the number of ovulations. To determine the LH concentration, a heterologous method of assay was used; this was based on the cross reaction of sheep plasma LH in a human LH radioimmunoassay system. As a result of the investigation, it was found that the peaks of LH were lower during the time of synchronized estrus and that these peaks occurred earlier than in the subsequent estrus. However, the differences were not statistically significant. On account of the limited material, the effect of the occurrence of the LH peak on the number of ovulations could not be established.     

GPR54-Dependent Stimulation of Luteinizing Hormone Secretion by Neurokinin B in Prepubertal Rats

Kisspeptin, neurokinin B (NKB) and dynorphin A (Dyn) are coexpressed within KNDy neurons that project from the hypothalamic arcuate nucleus (ARC) to GnRH neurons and numerous other hypothalamic targets. Each of the KNDy neuropeptides has been implicated in regulating pulsatile GnRH/LH secretion. In isolation, kisspeptin is generally known to stimulate, and Dyn to inhibit LH secretion. However, the NKB analog, senktide, has variously been reported to inhibit, stimulate or have no effect on LH secretion. In prepubertal mice, rats and monkeys, senktide stimulates LH secretion. Furthermore, in the monkey this effect is dependent on kisspeptin signaling through its receptor, GPR54. The present study tested the hypotheses that the stimulatory effects of NKB on LH secretion in intact rats are mediated by kisspeptin/GPR54 signaling and are independent of a Dyn tone. To test this, ovarian-intact prepubertal rats were subjected to frequent automated blood sampling before and after intracerebroventricular injections of KNDy neuropeptide analogs. Senktide robustly induced single LH pulses, while neither the GPR54 antagonist, Kp-234, nor the Dyn agonist and antagonist ({"type":"entrez-nucleotide","attrs":{"text":"U50488","term_id":"1277101","term_text":"U50488"}}U50488 and nor-BNI, respectively) had an effect on basal LH levels. However, Kp-234 potently blocked the senktide-induced LH pulses. Modulation of the Dyn tone by {"type":"entrez-nucleotide","attrs":{"text":"U50488","term_id":"1277101","term_text":"U50488"}}U50488 or nor-BNI did not affect the senktide-induced LH pulses. These data demonstrate that the stimulatory effect of NKB on LH secretion in intact female rats is dependent upon kisspeptin/GPR54 signaling, but not on Dyn signaling.     

Characterization of Luteinizing Hormone and Luteinizing Hormone Receptor and Their Indispensable Role in the Ovulatory Process of the Medaka

The molecular properties and roles of luteinizing hormone (Lh) and its receptor (Lhcgrbb) have not been studied for the medaka (Oryzias latipes), which is an excellent animal model for ovulation studies. Here, we characterized the medaka Lh/Lhcgrbb system, with attention to its involvement in the ovulatory process of this teleost fish. In the medaka ovary, follicle-stimulating hormone receptor mRNA was expressed in small and medium-sized follicles, while lhcgrbb mRNA was expressed in the follicle layers of all growing follicles. Experiments using HEK 293T cells expressing medaka Lhcgrbb in vitro revealed that gonadotropin from pregnant mare’s serum and medaka recombinant Lh (rLh) bound to the fish Lhcgrbb. The fish gonadotropin subunits Gtha, Fshb, and Lhb were essentially expressed at fairly constant levels in the pituitary of the fish during a 24-h spawning cycle. Using medaka rLh, we developed a follicle culture system that allowed us to follow the whole process of oocyte maturation and ovulation in vitro. This follicle culture method enabled us to determine that the Lh surge for the preovulatory follicle occurred in vivo between 19 and 15 h before ovulation. The present study also showed that oocyte maturation and ovulation were delayed several hours in vitro compared with in vivo. Treatment of large follicles with medaka rLh in vitro significantly increased the expression of Mmp15, which was previously demonstrated to be crucial for ovulation in the fish. These findings demonstrate that Lh/Lhcgrbb is critically involved in the induction of oocyte maturation and ovulation.     

Effects of Adrenocorticotropin Treatment on Estrogen,Luteinizing Hormone,and Progesterone Secretion in the Female Rhesus Monkey

Adrenocorticotropin (ACTH) was administered to female rhesus monkeys in order to determine the effects of adrenal axis activation on the endocrine events occurring during the menstrual cycle. ACTH injected twice daily during the follicular period and through the time of expected ovulation was found to prevent the rise of estrogens during the follicular phase. In addition, the ACTH administration also blocked the preovulatory surge of LH, prevented the luteal rise of progesterone, and extended the length of the menstrual cycle.     

Altered Luteinizing Hormone and Testosterone Secretion in Middle‐Aged Obese Men with Obstructive Sleep Apnea

Objective: To elucidate the causes for the decline in testosterone levels observed in men with obstructive sleep apnea (OSA). Research Methods and Procedures: We determined serum luteinizing hormone (LH) and testosterone levels every 20 minutes between 7 pm and 7 am with simultaneous sleep recordings in five obese middle‐aged men with OSA, in five age‐ and BMI‐matched controls, and in six lean young healthy men. Results: The mean and area under the curve (AUC) values of LH and testosterone were significantly lower in men with OSA compared with controls. Young controls had significantly more testosterone pulses of shorter interpulse duration than OSA subjects and middle‐aged controls. After adjusting for age and BMI, the three groups differed in mean and AUC values of LH and testosterone. Analysis of covariance, using BMI as a covariate, revealed a statistically significant group effect on mean and AUC testosterone values (p = 0.03; p < 0.003, respectively). Eliminating young controls, there was a significant positive correlation between the amount of LH and testosterone secreted at night. After partialling out age alone and BMI alone, the mean LH and mean testosterone were still positively correlated. Discussion: Thus, OSA is associated with decreased pituitary‐gonadal function. The decline in testosterone concentrations is due to obesity and advanced age and to a lesser degree to sleep fragmentation and hypoxia.