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1.
正Reproduction in mammals is primarily through fertilization of the oocytes and sperms generated by the females and males, respectively. Fusion of two haploid genomes leads to formation of the diploid zygotes, which sequentially gives rise to the pre-implantation and post-implantation embryos  相似文献   

2.
Blood ketone body level and ketone body ratio (acetoacetate/β hydroxybutyrate) are commonly used as clinical diagnostic indices.But there is no systematic study on the variability of these indices in the blood circulation.We investigated the concentration of ketone bodies within different segments of the circulation in fed ad libitum rats, starved rats and alloxan induced diabetic rats.Blood samples were drawn from femoral artery, suprarenal inferior vena cava and hepatic vein of each rat, respectively.The concentrations of acetoacetate and β hydroxybutyrate were measured by enzymatic method.To avoid mixing of the blood streams, appropriate strangulation of the vessels was taken when sampling.The total ketone body level was always the highest in the hepatic vein, secondary in the femoral artery and the lowest in the suprarenal vena cava in rats in different states.But surprisingly, the concentration of acetoacetate was the lowest in the hepatic vein and the highest in the femoral artery.The ketone body levels elevated in both starvation and diabetes, and the ketone body ratios were changed in the circulation.While blood flows through extra hepatic tissues, the total concentration of ketone body is undergoing degression, but the concentration of acetoacetate could be elevated due to the conversion of ketone body in extra hepatic tissues.Therefore, ketone body ratio is changeable in different segments of the blood circulation, including that between hepatic vein and artery.The correlation of ketone body ratio between arterial and hepatic venous blood could be effected by different pathophysiological states, such as starvation and diabetes.The “Redox theory” deserves a further discussion.  相似文献   

3.
The circadian timing system plays a key role in orchestrating lipid metabolism. In concert with the solar cycle, the circadian system ensures that daily rhythms in lipid absorption, storage, and transport are temporally coordinated with rest-activity and feeding cycles. At the cellular level, genes involved in lipid synthesis and fatty acid oxidation are rhythmically activated and repressed by core clock proteins in a tissue-specific manner. Consequently, loss of clock gene function or misalignment of circadian rhythms with feeding cycles (e.g., in shift work) results in impaired lipid homeostasis. Herein, we review recent progress in circadian rhythms research using lipidomics, i.e., large-scale profiling of lipid metabolites, to characterize circadian-regulated lipid pathways in mammals. In mice, novel regulatory circuits involved in fatty acid metabolism have been identified in adipose tissue, liver, and muscle. Extensive diversity in circadian regulation of plasma lipids has also been revealed in humans using lipidomics and other metabolomics approaches. In future studies, lipidomics platforms will be increasingly used to better understand the effects of genetic variation, shift work, food intake, and drugs on circadian-regulated lipid pathways and metabolic health.  相似文献   

4.
植物防御系统中抗病相关基因的研究进展   总被引:1,自引:0,他引:1  
万里红  周奕华  陈正华 《遗传》2002,24(4):486-492
本文论述了植物防御系统中抗病相关基因(resistance gene,R基因)的研究进展。列表总结了迄今已克隆的R基因,并将其归为四种不同的类型。综述了不同基因表达产物-R蛋白在细胞中的定位及其相应的功能。此外,还对R基因编码区的多态性、R基因在染色体上排列方式以及R基因的进化与起源等问题进行了讨论。 Abstract:This review comments on recent advances in research of disease resistance genes(R Genes) in defence system of plants.The R genes cloned up to date are summarized and classified roughly into four classes listed in the Table 1.The location and the founction of the R proteins,i.e.,the expressed products of different R genes in the cells are reviewed.In addition,the polymophism of coding region of R genes,the different fashions of R gene arrangement on the chromosomes,and the evolution and origin of R genes are discussed.  相似文献   

5.
The similarity and classification of sucking louse communities on 24 species of small mammals were studied in Yunnan Province, China, through a hierarchical cluster analysis. All the louse species on the body surface of a certain species of small mammals are regarded as a louse community unit. The results reveal that the community structure of sucking lice on small mammals is simple with low species diversity. Most small mammals usually have certain louse species on their body surface; there exists a high degree of host specificity. Most louse communities on the same genus of small mammals show a high similarity and are classified into the same group based on hierarchical cluster analysis. When the hosts have a close affinity in taxonomy, the louse communities on their body surface would tend to be similar with the same or similar dominant louse species (as observed in genus Rattus, Niviventer, Apodemus and Eothenomys). The similarity of sucking louse communities is highly consistent with the affinity of small mammal hosts in taxonomy. The results suggest a close relationship of co-evolution between sucking lice and their hosts.  相似文献   

6.
Gamma glutamyl transferases (GGT) are highly conserved enzymes that occur from bacteria to humans. They remove terminal y-glutamyl residue from peptides and amides. GGTs play an important role in the homeostasis of glutathione (a major cellular antioxidant) and in the detoxification of xenobiotics in mammals. They are implicated in diseases like diabetes, inflammation, neurodegenerative diseases and cardiovascular diseases. The physiological role of GGTs in bacteria is still unclear. Nothing is known about the basis for the strong conservation of the enzyme across the living system. The review focuses on the enzyme's physiology, chemistry and structural properties of the enzyme with emphasis on the evolutionary relationships. The available data indicate that the members of the GGT family share common structural features but are functionally heterogenous.  相似文献   

7.
SPECIES DIVERSITY AND COMMUNITY STRUCTURE OF SUCKING LICE IN YUNNAN, CHINA   总被引:14,自引:0,他引:14  
On the basis of investigating 9 counties (towns) in Yunnan Province of China, the species diversity and community structure of sucking lice on the body surface of small mammal hosts are studied in the paper. Species richness (S) is used to stand for the species diversity. The calculation of community diversity index and evenness are based on Shannon-Wiener‘s method. 2745 small mammals captured from the investigated sites belong to 10 families, 25 genera and 41 species in 5 orders (Rodentia, Insectivora, Scandentia, Logomorpha and Carnivora) while 18165 individuals of sucking lice collected from the body surface of the small mammal hosts are identified into 4 families, 6 genera and 22 species. The species of sucking lice are much less than the species of their hosts. Most species of small mammals have their fixed sucking lice on their body surface. One species of small mammals usually have few species of sucking lice (1 to 4 species). The close species of the hosts in the taxonomy are found to have the same or similar dominant species of sucking lice on their body surface. The results reveal that the species diversity of sucking lice on small mammals is very low with a very simple community structure. The results also imply there may be a close co-evolution relationship between the lice and the hosts.  相似文献   

8.
浣熊SRY-HMG box的克隆和序列分析   总被引:7,自引:0,他引:7  
We amplified the 197 bp HMG box sequence by using Polymerase Chain Reaction (PCR) with primers according to the known SRY sequence from male raccoon genomic DNA, and then cloned and sequenced. The nucleic acid and amino acid sequence comparison between raccoon and other mammals revealed high conservation of the SRY HMG box in mammals (about 80%), which implied that the DNA binding activity was crucial to mediate the action of SRY in sex determination. The variation of raccoon HMG box sequence mainly occurred on purine by replacement and missense mutation, which implicated that only the HMG box protein with advanced structure had efficient activity. The homology and difference between mammals HMG box was accorded to the evolution systematic tree.  相似文献   

9.
Portal vein thrombosis (PVT) is a common complication of liver cirrhosis. Gao et al. [1] reported that the prevalence of PVT in patients with cirrhosis is 8.82%. With the rapid developments in image-based diagnostic technology, the diagnosis rate of PVT is gradually increasing [2]. A follow-up study of 1243 patients with cirrhosis revealed that the cumulative incidences of PVT at 1, 3, and 5 years are 4.6%, 8.2%, and 10.7%, respectively [3]. PVT is a life-threatening factor for patients with cirrhosis, leading to portal hypertension and aggravating gastrointestinal hemorrhage [4]. The prevention of PVT has become a focus of clinical concern nowadays. It is well known that the establishment of animal models is the basis of scientific research. However, it is currently difficult to establish PVT models in large animals. Thereby, the establishment of a stable PVT animal model to study PVT is urgent and significant. We successfully established a new canine model of PVT involving the injection of an autologous thrombus through an indwelling catheter in the portal vein. This model is reliable for further studies of surgical treatment and drug therapy for PVT.  相似文献   

10.
In this work, we develop an artificial foldable wing that mimics the hind wing of a beetle (Allomyrina dichotoma). In real flight, the beetle unfolds forewings and hind wings, and maintains the unfolded configuration unless it is exhausted. The artificial wing has to be able to maintain a fully unfolded configuration while flapping at a desirable flapping frequency. The artificial foldable hind wing developed in this work is based on two four-bar linkages which adapt the behaviors of the beetle's hind wing. The four-bar-linkages are designed to mimic rotational motion of the wing base and the vein folding/unfolding motion of the beetle's hind wing. The behavior of the artificial wings, which are installed in a flapping-wing system, is observed using a high-speed camera. The observation shows that the wing could maintain a fully unfolded configuration during flapping motion. A series of thrust measurements are also conducted to estimate the force generated by the flapping-wing system with foldable artificial wings. Although the artificial foldable wings give added burden to the flapping-wing system because of its weight, the thrust measurement results show that the flapping-wing system could still generate reasonable thrust.  相似文献   

11.
猕猴肝门静脉系统和肝静脉系统的观察   总被引:4,自引:1,他引:3  
陈嘉绩 《兽类学报》1997,17(3):184-188
以铸型方法及实体解剖观察了猕猴(Macaca mulatta) 肝的门静脉分支和肝静脉分支。猕猴肝门静脉与人、猪、兔、牛、羊等相似, 同样可将全肝分成二叶四段, 即左叶、右叶; 左外侧段、左内侧段、右内侧段、右外侧段。尾状叶的左、右部可分别隶属于左叶和右叶。猕猴肝大静脉有左外侧叶肝静脉、左内侧叶肝静脉、肝中静脉、肝右静脉及尾状叶肝静脉。此外, 作者对哺乳动物门静脉分支的规律性, 猕猴肝大静脉的命名及吻合作了讨论。  相似文献   

12.
The extra- and intrahepatic venous afferent devices have been followed up in their evolution in all the classes of vertebrates and in man. There were studied 319 cases in 19 vertebrate species, in situ by the method of corrosion preparates with acid-resistant plastic materials or radiographies. The extraparenchymal afferent venous device shows an evolution characterized by the maintenance and improvement of the visceral hepatic venous system and by the gradual freeing of somatic parietal afferences, substantiating new anatomical notions like "liver visceralization", "hepatic parietal territories" and allowed the ascertainment of an evolutionary phyletic line of the liver based on the progressive diminution of the hepatic parietal territory. The basic characteristic type of intrahepatic distribution of the portal vein was sketched beginning with the testudine reptiles and was maintained including man. The liver segmentary angioarchitecture appeared already in birds. These findings allowed the homologation of the cleaved liver with the unitary liver of mammals and man as well as the homologation of the hepatic organ of mammals, birds and of some reptiles, and the understanding of the emergence variation of the portal vein ventrocranialis dexter.  相似文献   

13.
目的:探讨门静脉高压症脾切断流术后门静脉系统血栓形成的相关原因。方法:回顾性分析2010年4月-2011年12月我科450例因肝硬化门静脉高压症行脾切断流术患者的临床资料,应用超声多普勒检测手术前后门静脉血流速度、门静脉直径及脾静脉、肠系膜上静脉、门静脉血栓情况,用Logistic回归分析术前肝功能Child-Pugh分级、门静脉直径、门静脉血流速度、脾脏的质量及术后血小板数量与门静脉系统血栓形成的关系。结果:术前门静脉系统有血栓患者75例,占16.7%。术后门静脉血栓再形成率52.9%。Logistic单因素分析提示门静脉系统血栓形成与门静脉内径、门静脉血流速度、脾脏质量、血清总胆红素、术后血小板数量有关。多因素分析发现门静脉系统血栓形成与门静脉内径、门静脉血流速度、脾脏质量有关,而与血清总胆红素、术后血小板数量无关。结论:肝硬化门静脉高压症脾切除术后门静脉系统血栓形成与门静脉内径、门静脉血流速度、脾脏质量有关。  相似文献   

14.
The purpose of the study was to investigate the neuromuscular state in the preterm infants using surface electromyography (EMG). Ten preterm (gestational age, 31–32 weeks) and ten term infants (gestational age, 38–39 weeks) participated in the study in the second, fourth and sixth postnatal weeks. Linear and novel nonlinear parameters were used for the treatment of the interference EMG (iEMG) in four muscles (mm. bic. br. dext., trie. br. dext, tib. ant. sin., and gastr. sin.). In the preterm infants aged 33–37 weeks, both linear and nonlinear iEMG parameters were significantly lower in comparison to the term infants. Thus, the iEMG of the preterm infants was characterized by a more primitive time-domain structure and lower amplitude and spectrum frequency. In addition, unlike in term newborns, the lifetime dynamics of the iEMG parameters in the preterm infants was retarded. Thus, the motor system of a preterm infant is likely to be less prepared for postnatal life due to the shorter stay in utero. Nonetheless, the iEMG of the preterm infants may be characterized as more complex in comparison to the term newborns of the same postconceptual age. This may be attributed to the new postnatal sensory stimuli.  相似文献   

15.
The distribution of the pulmonary artery and vein of the orangutan lung was examined. The right pulmonary artery runs obliquely across the ventral side of the right bronchus at the caudally to the right upper lobe bronchiole. It then runs across the dorsal side of the right middle lobe bronchiole. Thereafter it runs obliquely across the dorsal side of the right bronchus, and then along the dorso-medial side of the right bronchus. This course is different from that in other mammals. During its course, it gives off branches which run mainly along the dorsal or lateral side of each bronchiole. The left pulmonary artery runs across the dorsal side of the left middle lobe bronchiole, then along the dorso-lateral side of the left bronchus, giving off branches which run along each bronchiole. The pulmonary veins run mainly the ventral or medial side of, along or between the bronchioles. In the left lung, the left middle lobe vein has two trunks; one enters the left atrium, and the other enters the left lower lobe pulmonary venous trunk. This is also different from that found in most mammals. Finally, the pulmonary veins enter the left atrium with four large veins.  相似文献   

16.
We have previously shown that intrasplenic fluid extravasation is important in controlling blood volume. We proposed that, because the splenic vein flows in the portal vein, portal hypertension would increase splenic venous pressure and thus increase intrasplenic microvascular pressure and fluid extravasation. Given that the rat spleen has no capacity to store/release blood, intrasplenic fluid extravasation can be estimated by measuring the difference between splenic arterial inflow and venous outflow. In anesthetized rats, partial ligation of the portal vein rostral to the junction with the splenic vein caused portal venous pressure to rise from 4.5 +/- 0.5 to 12.0 +/- 0.9 mmHg (n = 6); there was no change in portal venous pressure downstream of the ligation, although blood flow in the liver fell. Splenic arterial flow did not change, but the arteriovenous flow differential increased from 0.8 +/- 0.3 to 1.2 +/- 0.1 ml/min (n = 6), and splenic venous hematocrit rose. Mean arterial pressure fell (101 +/- 5.5 to 95 +/- 4 mmHg). Splenic afferent nerve activity increased (5.6 +/- 0.9 to 16.2 +/- 0.7 spikes/s, n = 5). Contrary to our hypothesis, partial ligation of the portal vein caudal to the junction with the splenic vein (same increase in portal venous pressure but no increase in splenic venous pressure) also caused the splenic arteriovenous flow differential to increase (0.6 +/- 0.1 to 1.0 +/- 0.2 ml/min; n = 8). The increase in intrasplenic fluid efflux and the fall in mean arterial pressure after rostral portal vein ligation were abolished by splenic denervation. We propose there to be an intestinal/hepatic/splenic reflex pathway, through which is mediated the changes in intrasplenic extravasation and systemic blood pressure observed during portal hypertension.  相似文献   

17.
Lungs of two chimpanzees (Pan troglodytes) were examined. The right pulmonary artery runs across the ventral side of the right upper lobe bronchiole and, then across the dorsal side of the right middle lobe bronchiole. Thereafter, it runs between the dorsal bronchiole system and the lateral bronchiole system, along the right bronchus. During its course, it gives off arterial branches which run along each bronchiole. The left pulmonary artery runs across the dorsal side of the left middle lobe bronchiole and then between the dorsal bronchiole system and the lateral bronchiole system. The branches of the pulmonary artery run mainly along the dorsal or lateral side of the bronchiole. The pulmonary veins run mainly along the ventral or medial side of the bronchioles, and between them. Finally, they enter the left atrium with four large veins, i.e. the common trunk of the right upper lobe vein and the right middle lobe vein, right lower lobe pulmonary venous trunk, left middle lobe vein, and left lower lobe pulmonary venous trunk.  相似文献   

18.
The vascularization of the pituitary region in Acipenser ruthenus L. (Chondrostei) is described. The adenohypophysis has no direct arterial supply but is fed exclusively by a pituitary portal system supplied through a pair of infundibular arteries. Distinct portal vessels connect the lateral part of the primary plexus of the neurohaemal area (the median eminence) with the secondary plexus of the pituitary gland. The primary plexus enters the pars distalis paramedially, apparently without the formation of distinct portal vessels. The neuro-intermediate lobe receives its blood supply exclusively from the primary plexus. The plexus intermedius gives off capillaries to the parenchyma of the intermediate lobe (an intermediate lobe sinus system). The saccus vasculosus receives (1) a “direct” supply, i.e. branches originating directly from the cerebral arteries and (2) an “indirect” supply, i.e. capillaries from the primary plexus. The pars distalis is drained into an unpaired ventral hypophysial vein, while a dorsal hypophysial vein, also unpaired, drains the plexus intermedius. These two veins join to form the unpaired hypophysial vein. The findings are discussed from comparative and functional viewpoints.  相似文献   

19.
The umbilical vein in adults is patent but collapsed. There is a membranous valve at its entrance into the left portal vein. Cannulation of the portal vein via the umbilical vein permits direct access to the portal system for portography and hepatography. This procedure was performed under local or general anesthesia in 30 patients and was successful in 22. It is useful in the investigation of patients with portal hypertension, and suspected intrahepatic tumours or abscesses. It gives excellent contrast visualization of the liver and definition of lesions as small as 1.0 cm. This technique is superior to both hepatic scanning and splenoportography.  相似文献   

20.
It has been reported that the intraportal infusion of glutamine in Munich-Wistar rats will cause depression of renal perfusion and the urinary excretion of salt and water. We have attempted to reproduce these findings in anaesthetized dogs. L-Glutamine was infused at doses between 120 and 150 mumol/min into the portal vein and femoral vein of anaesthetized dogs. No effect was observed on portal venous pressure, blood pressure, or kidney function. Similar data were obtained with D-glutamine. Liver biopsy revealed no abnormalities. When 1.5-3 micrograms histamine (free base) was infused into the portal system, portal venous pressure rose from 15.2 +/- 0.33 to 24.8 +/- 0.40 cmH2O (p < 0.05) (1 cmH2O = 98.1 Pa). Glutamine infusions do not appear to initiate hepatorenal reflexes in dogs as they have been reported to do in rats.  相似文献   

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