共查询到20条相似文献,搜索用时 15 毫秒
1.
羚牛(Budorcas taxicolor)部分脏器特点的观察 总被引:2,自引:2,他引:0
本文对2只羚牛的雌性生殖器官及肝、肾、脾等脏器进行了形态描述,并与黄牛及羊的相应器官进行了比较,为探讨羚牛的分类地位提供了解剖学资料。 相似文献
2.
R.N. Shukla Surjeet Singh Nibhriti Das Madhulika Baijal G.G. Sanwal 《Phytochemistry》1973,12(5):979-985
Considerable variations exist in the content of glucose, fructose, sucrose, starch and protein and in the activities of enzymes involved in carbohydrate metabolism between different parts of the banana plant (Musa paradisiaca). Sucrose synthetase is present in the highest concentration in rootstock and fruit pulp, and sucrose phosphate synthetase in the pseudostem. The highest ratio of the activity of sucrose phosphate synthetase to sucrose synthetase is found in leaves. Acid invertase is present in leaves, leaf-sheath and fruit pulp and is not demonstrable in rootstock and pseudostem. Neutral invertase activity is high in pseudostem and leaf-sheath. Starch phosphorylase is largely concentrated in fruit pulp and rootstock. The maximum activity of ATP:d-phosphoglucose (ADPG) pyrophosphorylase is found in rootstock. β-Amylase is not demonstrable in rootstock and is largely concentrated in leaf-sheath. Hexokinase is most active in rootstock and the lowest in leaves. Acid phosphatase and alkaline phosphatase activity is highest in fruit pulp and pseudostem. Glucosephosphate isomerase is most active in the rootstock and lowest in the leaves. 相似文献
3.
Walker RP Chen ZH Johnson KE Famiani F Tecsi L Leegood RC 《Journal of experimental botany》2001,52(356):565-576
To understand many aspects of the metabolism of complex plant structures such as leaves, fruit and roots it is important to understand how metabolic processes are compartmentalized between tissues. The aim of this article is to show how immunohistochemistry, in conjunction with biochemical and physiological studies, is useful in understanding both the function of an enzyme in a tissue and metabolic processes occurring in plant tissues. This is illustrated by two examples. Firstly, the use of immunohistochemisty in the localization of amino acids in plant tissues is described. Secondly, the use of immunohistochemistry in understanding the function of an enzyme in a tissue and the metabolic processes occurring within the tissue is described. To illustrate this the example of phosophoenolpyruvate carboxykinase (PEPCK), an enzyme which is present in many plant tissues in which its function is unknown, is used. Evidence is provided that PEPCK may play a role in pH regulation in tissues active in the metabolism of nitrogen. 相似文献
4.
Control of glucose metabolism in the perinatal period 总被引:1,自引:0,他引:1
C T Jones 《Journal of developmental physiology》1991,15(2):81-89
The central importance of glucose as a fuel for energy metabolism and growth of the fetus is clear as is the role of insulin in coordinating its utilisation by many fetal tissues. What is less clear is the qunatitative nature of the interaction between the fetus and placenta in organising glucose metabolism. Increasingly there is evidence that the fetus coordinates some of the supply of glucose to the placenta and that this is particularly important when uterine blood flow is reduced. It is unclear how this is regulated, but substrate cycles of glucose and lactate appear to make a significant contribution to carbohydrate metabolism in fetus and placenta. Another area as yet unresolved in the control of fetal glucose metabolism is the coordination of the changes that occur around the time of birth. Notable of these is the activation of glycogen mobilisation and of glucose synthesis and changes in the setting of glucose regulatory mechanism. These are briefly reviewed. 相似文献
5.
The expression pattern of the receptor tyrosine kinase gene EphB3 was examined during the early stages of chick embryogenesis, and is described in this report. In the gastrula, EphB3 is expressed in epiblast cells adjacent to and entering the anterior portion of the primitive streak; expression is extinguished once cells have ingressed. At headfold stages, EphB3 is strongly transcribed in the floor of the foregut and in anterior lateral endoderm, and is expressed in the subjacent cardiogenic mesoderm. EphB3 is transiently expressed in the lateral ectoderm, neural tube, and neural crest during these stages. Later neural expression is localized to the mesencephalon. In the somitic mesoderm, EphB3 is initially expressed in the sclerotome, but later is expressed predominantly in the dermatome. Prominent expression is also detected in the developing heart, liver, posterior ventral limb bud mesenchyme, pharyngeal arches, and head mesenchyme. 相似文献
6.
扬子鳄视觉器官组织学研究 总被引:11,自引:0,他引:11
本文用光镜和电镜研究了扬子鳄(Alligator sinensis)的组织学,同时测量了其眼球的一些光学参数.扬子鳄眼球呈扁圆球形,角膜径与球径的比值为1:1.44;晶状体与角膜的比值为1:1.40。角膜内具鲍氏膜;虹膜内的括约肌、睫状体内的睫状肌均属横纹肌,视细胞椭圆体内线粒体嵴突与线粒体长轴相平行,这与报道的其它鳄类不同。虹膜内未见扩瞳肌纤维,角膜缘缺巩膜小骨片,晶状体环垫薄,因而其视觉调节能力仍然很弱。视网膜中视细胞由视杆细胞、单锥细胞、双锥细胞组成,其中以视杆细胞占多数。视细胞与神经节细胞核比值平均为2.5:1,表明扬子鳄的组织结构与其弱光视觉相适应。 相似文献
7.
长毛对虾精子发生的研究:Ⅰ.精子的形态结构 总被引:14,自引:4,他引:14
利用电子显微镜技术结合细胞化学染色方法,研究长毛对虾精子形态结构,结果显示:长毛对虾精子由圆球状球体部和钉子状棘突部组成;精子全长约7μm;棘突及与之相联的球体表面平滑无突起,而与棘突相对的球体底面有指状突起。透射和冷冻蚀刻电镜显示:长毛对虾精子棘突包括顶体锥和顶体帽两部分;顶体锥向外突出形成精子的棘突,顶体帽覆盖在球体部的胞质及核区上方。成熟精子胞质极度退化,仅靠顶体帽边缘可见1—2个线粒体。球体的中央区域为近球形,呈Feul-gen阳性反应,为精子的核区。其结构松散,电子密度低,属非浓缩型,内布许多絮状物质,外由许多长短不一的膜性结构不规则排列成不连续的核膜结构。研究结果认为:长毛对虾精子属不动无鞭毛精子类型,其棘突部并非鞭毛结构而是顶体的位置。 相似文献
8.
Survivin是在肿瘤组织及胚胎中发现的一类细胞因子,它是IAPs(inhibitorsofapoptosisprotein)家族的成员之一,具有其独特的分子结构和组织表达特异性,在细胞中参与细胞周期的调控,主要在细胞周期的G2/M期通过抑制caspase-3及caspase-7的活性发挥作用.Survivin在细胞中的活性可能受p53的调节.Survivin也是胚胎发育早期过程中调节细胞分裂分化的一类重要的因子.对Survivin的研究对于肿瘤治疗的研究及揭示胚胎早期的发育机制有重要的意义. 相似文献
9.
几种不同进化程度动物细胞内质网超微结构的比较研究 总被引:1,自引:0,他引:1
应用稼射电镜技术,高锰酸钾固定扫描电镜技术及生化分离技术,比较研究了家兔、家鸽、蟾蜍,鲤鱼、脉红螺肝细胞和眼虫的内质网超微结构及含量。透射电镜观察结果显示:在高等哺乳动物肝细胞内质网丰富,以扁囊结构为主,在整个细胞质内均有分布,主要存在于核周围,并伴有伴随线粒体分布的特征;蟾蜍肝细胞内质网稀少,以长管状平行排列,分布在细胞质的局部,鲤鱼肝细胞内质网呈小泡状均匀分布在细胞质中,脉红螺肝细胞及眼虫细胞 相似文献
10.
鼎湖山顶级森林生态系统水文要素时空规律 总被引:14,自引:4,他引:10
运用连续7a(1993~1999)的水文观测资料,对南亚热带顶级生态系统鼎湖山季风常绿阔叶林集水区水文要素时空规律进行分析,得到如下一些主要结论:(1)鼎湖山多年平均降水量为1910mm,湿季降水量占年降水量80%,干季仅占20%。6月份的降水量最大,1月份最小。(2)季风常绿阔叶林冠层截留率为31.8%,湿季的截留量占全年截留量的66.7%,截留量最大值和最小值所在的月份分别为7和1月份。各月的截留率差异很大,截留量大的月份,截留率较低;截留量小的月份,截留率较高。(3)季风常绿阔叶林集水区多年平均总径流量953.0mm,总径流系数49.9%,其中地表径流量为252.3mm,地表径流系数13.2%;地表径流与降水量之间存在二次抛物线型回归关系,与降水强度的关系不大,这说明季风常绿阔叶林的产流形式是是蓄满产流。(4)季风常绿阔叶林多年平均蒸散948.2mm,占同期降水量的49.7%;蒸散力1031.4mm,年蒸散系数为0.92,蒸散月变化规律较降水量的月变化规律有所滞后。(5)系统贮水量的月变化很大,2~8月份,系统处于蓄水阶段;9月份至翌年1月份,系统处于失水阶段。蓄水和失水的最大值分别出现在湿季和干季的第一个月,即4月份和10月份。(6)集水区多年平均水量总输入2129.9mm,实际输入1910mm(降水量),其中219.9mm的水量输入是由系统贮水量变化而产生。支出的总水量2129.9mm,实际支出1901.3mm(径流和蒸散量),其中228.6mm的水量支出是由系统贮水量变化引起的。 相似文献
11.
1. beta-Hydroxy-beta-methyl[3-(14)C]glutaryl-CoA is efficiently incorporated into rubber on incubation with Hevea brasiliensis latex, and the incorporation is diminished in the presence of unlabelled mevalonate. beta-Hydroxy-beta-methylglutaric acid is not utilized for rubber synthesis, but inhibits the formation of rubber from beta-hydroxy-beta-methylglutaryl-CoA. 2. The incorporation of beta-hydroxy-beta-methylglutaryl-CoA into rubber is stimulated equally by NADP(+) and NADPH and less so by NAD(+) and NADH. ATP is slightly stimulatory and CoA is inhibitory. 3. beta-Hydroxy-beta-methylglutaryl-CoA reductase is concentrated in the sediment (bottom fraction) formed by centrifuging latex at low speed and the enzyme is unstable in the absence of cysteine or GSH. The formation of NADPH takes place in the latex serum. 4. There is a marked seasonal variation in the extent of beta-hydroxy-beta-methylglutaryl-CoA incorporation into rubber in latex, but mevalonate incorporation is relatively constant. This observation, together with the finding that beta-hydroxy-beta-methylglutaryl-CoA reduction is the rate-limiting step in the formation of rubber from beta-hydroxy-beta-methylglutaryl-CoA, suggests that the conversion of beta-hydroxy-beta-methylglutaryl-CoA into mevalonate is of importance in the regulation of rubber synthesis. 5. Evidence suggesting that beta-hydroxy-beta-methylglutaryl-CoA lyase is present in H. brasiliensis latex has been obtained. 相似文献
12.
13.
The small molecular weight RNAs of the HeLa cell have been located in specific subcellular fractions. SnA is located in the nucleolus and is partially bonded to nucleolar 28S RNA. SnD, the most abundant of the small nuclear RNAs, is partially released from the nucleus when the nuclear preparation is briefly warmed. SnF is released from the nuclei when chromatin is digested with the micrococcal nuclease and not when pancreatic DNAase is used. The remainder of the small nuclear species remain in the nucleus following the digestion of chromatin and are concluded to be elements of the “nuclear skeleton.” SnK is found predominantly in the cytoplasm, but migrates quantitatively to the nuclear fraction in the presence of high levels of actinomycin D. ScL is totally cytoplasmic and is partially bound to cell membranes. It is the 7S RNA found in oncornavirus virions. All the small nuclear RNAs appear initially in the cytoplasmic fraction before fixation in the nucleus. Two short-lived cytoplasmic species behave kinetically as precursors to the stable nuclear RNAs. 相似文献
14.
Vernigora AN Gengin MT Bardinova ZhS Smetanin VA Petrushova OP 《Ukrainski? biokhimicheski? zhurnal》2003,75(5):99-102
It is revealed, that the activity of neuropeptide metabolism enzymes (carboxypeptidase H, phenylmethylsulfonilfluorid-inhibited carboxypeptidase) in the female rat tissues depends upon the stage of estrus cycle. The carboxypeptidase H activity in the pituitary gland is the highest in proestrus; it is almost 3 times higher in comparison with diestrus; it is a little bit higher in striatum on the stage of estrus, than in diestrus and proestrus, in adrenals on the stage of proestrus and estrus it is a little bit lower, than in diestrus; in the ovaries on the stage of proestrus it is much higher, than in estrus and diestrus. The activity of PMSF-inhibited carboxypeptidase in ovaries on the stage of proestrus and diestrus is 1.7-1.8 times higher, than at the stage of diestrus. The activity of carboxypeptidase M in adrenal tissue at the stage of proestrus is 35-40% of that at the stage of diestrus and estrus. The activity of carboxypeptidase M in the ovaries at the stage of diestrus is 45-50% of that at the stage of diestrus and estrus. The role of the investigated enzymes in cyclic changes of a level of biologically active peptides and in regulation of estrus cycle is discussed. 相似文献
15.
Hopkins CR 《Tissue & cell》1970,2(1):83-98
Methods of bioassay and electron microscopy have been employed in the study of secretion of MSH from single pars intermedia/nervosa lobes maintained in vitro. It is shown that in a modified Krebs-Ringer medium the tissue displays an endogenous capacity for the synthesis and release of MSH. The amount of MSH produced is directly related to the development and functioning of the endoplasmic reticulum within the MSH cell, and although a net increase in the amount of MSH is adversely affected by anaerobic conditions and low temperature it is independent of an exogenous amino acid supply. The release of MSH, which is studied both independently and in association with concomitant synthesis, is also significantly reduced by anaerobic conditions and low temperature. Of the inorganic ions present in the medium only Ca(++) is essential for the synthesis and release of MSH. The evidence suggests that more than one step in the secretory process is dependent upon an exogenous supply of Ca(++) since in its absence the inhibition of MSH release is immediate but reversible, whereas although the inhibition of synthesis is delayed it is eventually complete and irreversible. 相似文献
16.
P A Vunder 《Uspekhi sovremenno? biologii》1970,70(1):106-119
Literature is reviewed in which the role of hormones, particularly progesterone and estrogens, and their interaction in the development of contraceptive changes in the uterus and in the regulation of the process of ovicellular implantation is emphasized. Emphasis is placed on hormonal insufficiency in the emergence of experimental and natural blockage of implantation and of asynchronic implantation. It is shown that ovicellular implantation is not automatic or a process divorced from its external environment. The role of several exogenous irritations in the blockade of implantation is examined. 相似文献
17.
红腹锦鸡血细胞的光镜和扫描电镜观察 总被引:11,自引:3,他引:8
为了探讨红腹锦鸡(Chrysolophus pictus)血细胞的形态特征,为生理学研究提供生物学基础资料,利用光镜和扫描电镜观察了红腹锦鸡血细胞的形态特征。结果表明,红腹锦鸡红细胞呈椭圆形或扁圆形,表面光滑,具核;白细胞为球形,体大,淋巴细胞表面有绒毛状突起,嗜中性粒细胞核一般分2~5叶,嗜酸性粒细胞核一般分2叶,嗜碱性粒细胞核分2~3叶,单核细胞表面粗糙不平,核大,呈肾形或圆形;凝血细胞呈球形或不规则形。 相似文献
18.
维吾尔族的体质特征研究 总被引:37,自引:12,他引:25
1991年5月,对新疆伊梨维吾尔族529人(男271,女258)进行了活体观察和测量。观察29项,测量92项。维吾尔族的主要特征是:黑直发,黑褐色眼,眉毛较浓密,大都有上眼脸皱褶,鼻根中等偏高,大多为直形鼻,鼻尖向前,鼻基部下垂,大多有达尔文结节,耳垢湿型。头面部指数分型,属于特短头型,阔头型和高头型。身材中等偏高,平均身高男168.6毫米,女1578.8毫米。 相似文献
19.
Claspin is involved in ATR-dependent activation of Chk1 during DNA replication and in response to DNA damage. We show that degradation of Claspin by the ubiquitin-proteosome pathway is regulated during the cell cycle. Claspin is stabilized in S-phase but is abruptly degraded in mitosis and is absent from early G(1) cells in which the phosphorylation of Chk1 by ATR is abrogated. In response to hydroxyurea, UV or aphidicolin, Claspin is phosphorylated in the Chk1-binding domain and its protein levels are increased in an ATR-dependent manner. Thus, the Chk1 pathway is regulated through both phosphorylation of Claspin and its controlled degradation. 相似文献
20.
V Giancotti E Russo F de Cristini G Graziosi F Micali C Crane-Robinson 《The Biochemical journal》1984,218(2):321-329