共查询到20条相似文献，搜索用时 187 毫秒
1.
Immature 25-day-old mice were injected daily with 1 microgram of arginine vasotocin for 3 or 4 days and killed 24 hours after the last injection. The ovaries were 30 percent smaller in treated females than in controls. The ventral prostates and accessory organs (seminal vesicles and coagulating glands) were less than half the size of these structures in control males. Similar results were observed when 15-day-old mice were given similar injections and killed 2 weeks after the last injection; furthermore, testis weights were 28 percent smaller than those of controls. It is speculated that arginine vasotocin, which has been found in mammalian pineal glands, might mediate effects of the pineal gland on normal sexual development. 相似文献
2.
The intracarotid injection of both synthetic melanocyte-stimulating hormone release-inhibiting factor (MIF) and purified MIF prepared from bovine hypothalami induces arginine vasotocin release into cerebrospinal fluid of cats and significantly decreases the pineal arginine vasotocin content at 5 minutes after the injection. The present results demonstrate an extrapituitary endocrine effect of synthetic and purified bovine MIF. 相似文献
3.
Pineal melatonin may play an important role in regulation of vertebrate circadian rhythms and in human affective disorders. In some mammals, such as hamsters and sheep, melatonin is involved in photoperiodic time measurement and in control of reproduction. Although wild mice (Mus domesticus) and some wild-derived inbred strains of mice have melatonin in their pineal glands, several inbred strains of laboratory mice (for example, C57BL/6J) were found not to have detectable melatonin in their pineal glands. Genetic analysis suggests that melatonin deficiency in C57BL/6J mice results from mutations in two independently segregating, autosomal recessive genes. Synthesis of melatonin from serotonin in the pineal gland requires the enzymes N-acetyltransferase (NAT) and hydroxyindole-O-methyltransferase (HIOMT). Pineal glands from C57BL/6J mice have neither NAT nor HIOMT activity. These results suggest that the two genes involved in melatonin deficiency are responsible for the absence of normal NAT and HIOMT enzyme activity. 相似文献
4.
迄今为止,已发现有11种生殖激素参与龟类生殖调控。雌二醇和睾酮在促性腺激素释放激素、卵泡刺激素和黄体生成素的调控下主导调控龟类性腺发育、配子生成、交配、产卵及子代性别决定等重要生殖环节。孕酮、前列腺素、精氨酸催产素、皮质酮、甲状腺素和褪黑激素协同调节龟类生殖活动。在人工繁殖方面,使用GnRH等有助于克服龟类繁殖障碍,提高繁殖效率。对生殖激素对龟类生殖活动的调控作用与机理及其应用的研究进展进行了综述。 相似文献
5.
Identification of an intracellular peptide segment involved in sodium channel inactivation 总被引：25，自引：0，他引：25
Antibodies directed against a conserved intracellular segment of the sodium channel alpha subunit slow the inactivation of sodium channels in rat muscle cells. Of four site-directed antibodies tested, only antibodies against the short intracellular segment between homologous transmembrane domains III and IV slowed inactivation, and their effects were blocked by the corresponding peptide antigen. No effects on the voltage dependence of sodium channel activation or of steady-state inactivation were observed, but the rate of onset of the antibody effect and the extent of slowing of inactivation were voltage-dependent. Antibody binding was more rapid at negative potentials, at which sodium channels are not inactivated; antibody-induced slowing of inactivation was greater during depolarizations to more positive membrane potentials. The peptide segment recognized by this antibody appears to participate directly in rapid sodium channel inactivation during large depolarizations and to undergo a conformational change that reduces its accessibility to antibodies as the channel inactivates. 相似文献
6.
Circadian clock in culture: N-acetyltransferase activity of chick pineal glands oscillates in vitro 总被引：8，自引：0，他引：8
N-Acetyltransferase activity was measured in organ-cultured chick pineal glands. A circadian rhythm of enzyme activity persisted in cultured glands for up to 4 days. The phase of the rhythm in vitro closely approximates its phase in vivo. These observations demonstrate that the pineal gland of chicks contains (or is) a self-sustained circadian oscillator. 相似文献
7.
Adenyl cyclase activity in rat pineal gland: effects of chronic denervation and norepinephrine 总被引：7，自引：0，他引：7
Adenyl cyclase activity in the pineal gland of rats was determined by measuring the rate of formation of radioactive cyclic 3',5'-adenosine monophosphate from (14)C-labeled adenosine triphosphate. Norepinephrine added in vitro to pineal homogenates enhanced this activity, while denervation of the pineal gland by superior cervical ganglionectomy did not significantly reduce it. The enzyme in these denervated glands was more responsive to the stimulatory effects of norepinephrine. 相似文献
8.
Pineal gland: influence on gonads of male rats treated with androgen 3 days after birth 总被引：1，自引：0，他引：1
Either blinding or the injection of 1 milligram of testosterone propionate into male Sprague-Dawley rats, 3 days old, results in testes and accessory organs (seminal vesicles and coagulating glands) that are smaller than normal when the rats are 72 days old. The response to blinding is prevented by removal of the pineal gland, whereas the response to treatment with testosterone is unaffected by pinealectomy. Combination of the two treatments in 3-day- old rats causes testes to be less than one-third their normal size at 72 days of age; pinealectomy in these rats permits the reproductive organs to grow to the same size as those in the androgen-treated animals. 相似文献
9.
The carboxy terminus of the precursor to vasopressin and neurophysin: immunocytochemistry in rat brain 总被引：1，自引：0，他引：1
A pituitary glycopeptide whose amino acid sequence was previously identified has now been recognized as the final portion of the precursor to arginine vasopressin and its associated neurophysin. Immunocytochemical techniques with antiserums against this 39 amino acid peptide and vasopressin were used to study their distribution in the rat central nervous system. The peptide is located in vasopressin-synthesizing cells in the neurosecretory magnocellular nuclei. Positively stained fibers project from the magnocellular nuclei through the median eminence to the posterior pituitary. Studies of the homozygous Brattleboro rat, which is known to be deficient in the production of vasopressin and its related neurophysin, also show the absence of immunoreactivity to this peptide. These immunocytochemical data strongly indicate that the peptide is synthesized with vasopressin. 相似文献
10.
11.
Restoration of inactivation in mutants of Shaker potassium channels by a peptide derived from ShB 总被引：51，自引：0，他引：51
Site-directed mutagenesis experiments have suggested a model for the inactivation mechanism of Shaker potassium channels from Drosophila melanogaster. In this model, the first 20 amino acids form a cytoplasmic domain that interacts with the open channel to cause inactivation. The model was tested by the internal application of a synthetic peptide, with the sequence of the first 20 residues of the ShB alternatively spliced variant, to noninactivating mutant channels expressed in Xenopus oocytes. The peptide restored inactivation in a concentration-dependent manner. Like normal inactivation, peptide-induced inactivation was not noticeably voltage-dependent. Trypsin-treated peptide and peptides with sequences derived from the first 20 residues of noninactivating mutants did not restore inactivation. These results support the proposal that inactivation occurs by a cytoplasmic domain that occludes the ion-conducting pore of the channel. 相似文献
12.
Polydipsia and polyuria are pronounced in chickens of a selected strain and this diabetes insipidus is inherited. The kidneys of such birds are capable of an antidiuretic response when lysine vasopressin or arginine vasotocin is injected. Osmotic pressure and sodium concentration of the plasmas of normal and mutant chickens are identical. Chicks predicted to have diabetes insipidus on the basis of parental pedigree are polydipsic. 相似文献
13.
AIDS-Kaposi's sarcoma-derived cells express cytokines with autocrine and paracrine growth effects 总被引：51，自引：0，他引：51
B Ensoli S Nakamura S Z Salahuddin P Biberfeld L Larsson B Beaver F Wong-Staal R C Gallo 《Science (New York, N.Y.)》1989,243(4888):223-226
When grown in vitro, cells from Kaposi's sarcoma lesions of AIDS patients (AIDS-KS cells) constitutively release several growth promoting activities. When inoculated into nude mice, the AIDS-KS cells induce a KS-like lesion of mouse origin. Here it is shown that the AIDS-KS cells express messenger RNA for a complex mixture of cytokines that correlate with several of the biological activities of these cells. Basic fibroblast growth factor, which is a potent angiogenic factor, and interleukin-1 messenger RNAs are expressed at very high levels and seem to account for a large proportion of the activities, since their corresponding proteins are released in biologically active form into the culture media where they induce autocrine and paracrine growth effects. 相似文献
14.
Gas chromatography with electron capture detection was used to quantitate melatonin in single human pineal glands. The sensitivity of this melatonin assay is in the low picogram range. A 24-hour rhythm of pineal melatonin content was observed. 相似文献
15.
16.
采用RT-PCR方法从奥利亚罗非鱼丘脑中扩增出长约386 bp的目的序列GnRH/GAP,先将其克隆到T载体上,通过酶切鉴定、序列测定分析,确认序列的正确性后,将此片段克隆到表达载体pMAL-c2x中构建重组表达质粒pMAL-GnRH/GAP,再转化到大肠杆菌TB1中,经IPTG诱导后成功表达出与预期大小相符的相对分子量约56 000的融合蛋白。 相似文献
17.
《农业科学学报》2016,(7)
Programmed cell death(PCD) plays a critical role in the development of plant pigment glands, while H_2O_2, which is a kind of reactive oxygen species(ROS) produced by the aerobic metabolism of cells, acts as an important signal in this process. Here, we investigated the temporal and spatial dynamics of accumulated H_2O_2 in pigment glands of Gossypium hirsutum L. with 3,3-diaminobenzidine(DAB) staining, 2',7'-dichlorodihydrofluorescein diacetate(DCFH2)-DA fluorescent labeling and Ce Cl3 cytochemical localization techniques. The results showed that the pigment glands of G. hirsutum could generate H_2O_2, and the amount and localization of H_2O_2 varied at different developmental stages. At the early developmental stage, a small amount of H_2O_2 accumulated in the vacuole membrane of pigment gland cells. At the intermediate stage, a large number of H_2O_2 appeared in the vacuole membrane, while cell walls started to accumulate a small amount of H_2O_2. When pigment gland cell degraded, H_2O_2 mainly accumulated on the chloroplast envelope membrane of inner sheath cells. With the degradation of the sheath cells, H_2O_2 was detected in cell wall and the membrane of secretory vesicles which contains the preliminary contents of pigment gland. With the pigment glands completely maturation, H_2O_2 would disappeared. The accumulation sites of H_2O_2 are consistent with the process of PCD of individual gland cells, which started from the degradation of intracellular membrane and ended with the degradation of cell walls. Thus H_2O_2 probably plays an important role in the development of pigment glands. In addition, the development of pigment glands and the generation of H_2O_2 are not associated with the light, and no H_2O_2 was detected in the secretions of pigment glands. 相似文献
18.
Nerve growth factor of very high yield and specific activity 总被引：1，自引：0，他引：1
Nerve growth factor has been isolated from submaxillary glands of mnature male mice at specific activities about a million times, and in yields of biological activity ten million times, greater than best previous results. The major improvement in the isolation is related to the separation of a highly active tosylarginine methyl esterase present in cruder preparations. The new nerve growth factor may be an entity different from the older one, although no gross differences in the qualitative aspects of their actions are apparent on superficial examination of chick ganglia influenced by them. The neurites which develop from a ganglion in the presence of nerve growth factor are of nearly equal length. The amount of nerve growth factor determines the number of neurites but not the extent of individual development. The amount of the new nerve growth factor which evokes the appearance of a hundred neurites from a single ganglion appears to be about ten molecules. Since each neurite seems to arise from a different neuron each molecule of nerve growth factor must affect several cells. This result can be rationalized by a catalytic mechanism or by indirect action of nerve growth factor through a hypothetical cell which produces a neurite evocator on contact with the molecule of nerve growth factor. 相似文献
19.
水牛胃肠胰(GEP)系统中生长抑素免疫反应细胞的形态和分布 总被引：2，自引：0，他引：2
生长抑素免疫反应细胞存在于水牛胃肠道各段管壁中,但主要分布在胃腺和十二指肠的肠腺。胃和十二指肠粘膜上皮,以及十二指肠腺也有少量生长抑素免疫反应细胞。十二指肠以后段肠管的生长抑素免疫反应细胞数量极少,偶而可见位于腺上皮细胞之间。胰中的生长抑素免疫反应细胞主要位于胰岛,极少数分布在主胰管上皮和粘液腺以及小叶间导管上皮。生长抑素免疫反应细胞根据其形态分为三类:(1)锥形细胞,主要分布在腺上皮,其顶端朝向腺腔;(2)长形细胞,存在于粘膜上皮中;(3)不规则形细胞,位于胰岛。生长抑素免疫反应细胞既不被Grimelius方法着色,又不与Masson改良法产生反应。 相似文献
20.
促性腺激素释放激素(gonadotropin-releasing hormone,GnRH)是下丘脑分泌产生的神经激素,对脊椎动物生殖的调控起重要作用。本研究通过RT-PCR方法从奥利亚罗非鱼丘脑中扩增出长约400 bp的目的序列GnRH,并将其克隆到T载体中,经酶切鉴定、序列测定分析后表明其与尼罗罗非鱼和乌颊海鲷具有较高的同源性,处于同一个进化分支上;而与日本青、金鱼、拟鲤、壁虎等的同源性较低。将此cDNA片段定向克隆到表达载体pMAL-c2x中构建重组表达质粒pMAL-GnRH,转化到大肠杆菌TB1中,0.3M IPTG诱导4 h后成功表达出与预期大小相符的约56 kD的融合蛋白。表明大肠杆菌表达系统可以成功地体外表达奥利亚罗非鱼GnRH,为进一步制备抗体了解其免疫调节作用奠定基础。 相似文献