不同流速对流水槽大口黑鲈生长性能、抗氧化能力、能量代谢及组织结构的影响

研究旨在探明池塘内循环流水养殖(Inner-Pond Raceway Aquaculture, IPRA)系统中不同水流速度对大口黑鲈(Micropterus salmoides)生长性能、抗氧化能力、能量代谢及组织结构的影响。选取已驯食好、体质健康、大小均一的大口黑鲈[放养规格为(8.13±0.82) g]192尾,随机分配到4个模拟水槽中,每组3个重复,每个重复16尾。养殖试验设置空白静水组和3个水流速度组,分别为低流速0.2 m/s、中流速0.4 m/s和高流速0.6 m/s,养殖周期为154d。结果显示:(1)中流速组大口黑鲈的增重率和特定生长率显著高于其他3个处理组(P<0.05);中、高流速组肥满度显著低于静水组和低流速组(P>0.05);大口黑鲈内脏脂肪指数随着流速的增加而显著降低(P<0.05);(2)中流速组肌肉粗蛋白显著高于其他3个处理组(P<0.05),静水组和低流速组肌肉粗脂肪含量显著高于中、高流速组(P<0.05);中、高流速组肝脏粗蛋白显著高于静水组和低流速组(P<0.05);(3)中、高流速组血清中甘油三酯和总胆固醇显著...     

The age factor in blood flow in the calf and in vascular resistance at rest and in reactive hyperaemia.

The blood flow and vascular resistance in the calf were studied in two groups of healthy subjects (mean ages 22 and 49 years) at rest and in reactive hyperaemia produced by five minutes' ischaemia of the lower limb. The blood flow was determined by venous occlusive plethysmography and vascular resistance was computed from the mean blood pressure measured by auscultation on the arm and from the blood flow in the calf, at rest and during reactive hyperaemia. The resting flow and blood flows throughout practically the whole time of hyperaemia were found to be significantly smaller in young individuals. The maximal flow was significantly lower, the maximal flow time was significantly prolonged in young subjects. The recovery time and repayment of the flow debt in the two groups were the same. Vascular resistance in the calf was significantly greater in young subjects, both at rest and during dilatation. We assume from the results that the capacity of the arterial system in the lower limbs is significantly smaller in young individuals.     

Histochemical studies on the mechanism of macromolecule leakage across the glomerular capillary wall. Barrier effect of the anionic groups of the capillary wall against the serum protein leakage

For the purpose of revealing the barrier effect of the anionic groups of glomerular capillary wall against the serum protein leakage, morphologic and histochemical observations were made on the rat kidney perfused in situ with three kinds of cationic macromolecules different in chemical characteristics followed by blood flow restoration. The polyethyleneimine perfusion resulted in the complete disapperance of ionized anionic groups of glomerular capillary and the massive protein leakage through glomeruli by blood flow restoration. Cationic ferric colloid perfusion induced moderate protein leakage, and avidin perfusion was less in neutralization effect of anionic groups and the protein leakage was of least. The protein leakage from glomeruli, however, was stopped or markedly suppressed soon after the blood flow restoration by the newly formed functioning anionic barrier probably by some particular serum protein deposition. The findings indicate that the deionization of the glomerular capillary wall will not be responsible for the persistent albuminuria.     

Histochemical studies on the mechanism of macromolecule leakage across the glomerular capillary wall

Summary For the purpose of revealing the barrier effect of the anionic groups of glomerular capillary wall against the serum protein leakage, morphologic and histochemical observations were made on the rat kidney perfused in situ with three kinds of cationic macromolecules different in chemical characteristics followed by blood flow restoration. The polyethyleneimine perfusion resulted in the complete disappearance of ionized anionic groups of glomerular capillary and the massive protein leakage through glomeruli by blood flow restoration. Cationic ferric colloid perfusion induced moderate protein leakage, and avidin perfusion was less in neutralization effect of anionic groups and the protein leakage was of least. The protein leakage from glomeruli, however, was stopped or markedly suppressed soon after the blood flow restoration by the newly formed functioning anionc barrier probably by some particular serum protein deposition. The findings indicate that the deionization of the glomerular capillary wall will not be responsible for the persistent albuminuria.     

Transcoronary gene transfer of SERCA2a increases coronary blood flow and decreases cardiomyocyte size in a type 2 diabetic rat model

The Otsuka Long-Evans Tokushima fatty rat is an animal model of Type 2 diabetes mellitus (DM), which is characterized by diastolic dysfunction associated with decreased sarcoplasmic reticulum Ca(2+)-ATPase (SERCA2a). The aim of this study was to examine whether gene transfer of SERCA2a can influence coronary blood flow and cardiomyocyte diameter in this model. DM rats were injected with adenovirus carrying SERCA2a (DM+SERCA) or beta-galactosidase gene (DM+betaGal). Coronary blood flow was measured in cross-circulated excised hearts 3 days after infection. Although in all groups coronary blood flow remained unchanged even if left ventricular (LV) volume or intracoronary Ca(2+) infusion was increased, the DM+SERCA group showed a sustained increase in coronary blood flow compared with the other groups. This result suggests that the sustained high coronary blood flow is a specific response in SERCA2a-overexpressed hearts. Although the LV weight-to-body weight ratio (LV/BW) and cardiomyocyte diameter were higher in the DM and DM+betaGal groups than in the non-DM group, in the DM+SERCA group, these measurements were restored to non-DM size. The percentages of collagen area in the three DM groups was significantly higher than results shown in non-DM rats, and there were no significant differences in collagen area percentage among the three DM groups. These results suggest that a lowered LV/BW by SERCA2a overexpression is due mainly to reduced size of cardiomyocytes without any changes in collagen area percentage. In conclusion, in DM failing hearts, SERCA2a gene transfer can increase coronary blood flow and reduce cardiomyocyte size without reduction in collagen production.     

The effects of prostacyclin analog OP-41483 on normothermic liver ischemia and reperfusion injury in rats

To estimate the effects of the prostacyclin analog (OP-41483) on normothermic liver ischemia and reperfusion injury, saline (Group 1, N = 8), heparin (group 2, N = 8, 100 u/kg) or OP-41483 (group 3, N = 8, 400 ng/kg/min) was infused intravenously for 30 min before and after liver ischemia in rats. There were no significant differences in survival, or transaminase at 30 min after reperfusion among the three groups. Hepatic vessel flow and tissue flow were measured for the first 30 min after reperfusion. Hepatic tissue flow increased for the first 30 min after reperfusion in the group 3 rats, but not in the groups 2 and 3 rats. There were significant differences in hepatic tissue flow between the groups 1 and 3 rats at 20 min (p < 0.05), as well as significant differences between the groups 1 and 3 rats (p < 0.01) and the groups 1 and 2 rats (p < 0.05) at 30 min after reperfusion. There were no significant differences in total hepatic inflow among the three groups. Our data suggest that OP-41483 exerts beneficial effects by improving the microcirculation and increasing the effective hepatic blood flow in the ischemically injured liver after reperfusion.     

The effects of flow on schooling Devario aequipinnatus: school structure,startle response and information transmission

To assess how flow affects school structure and threat detection, startle response rates of solitary and small groups of giant danio Devario aequipinnatus to visual looming stimuli were compared in flow and no‐flow conditions. The instantaneous position and heading of each D. aequipinnatus was extracted from high‐speed videos. Behavioural results indicate that (1) school structure is altered in flow such that D. aequipinnatus orient upstream while spanning out in a crosswise direction, (2) the probability of at least one D. aequipinnatus detecting the visual looming stimulus is higher in flow than no flow for both solitary D. aequipinnatus and groups of eight D. aequipinnatus; however, (3) the probability of three or more individuals responding is higher in no flow than in flow. These results indicate a higher probability of stimulus detection in flow but a higher probability of internal transmission of information in no flow. Finally, results were well predicted by a computational model of collective fright response that included the probability of direct detection (based on signal detection theory) and indirect detection (i.e. via interactions between group members) of threatening stimuli. This model provides a new theoretical framework for analysing the collective transfer of information among groups of fishes and other organisms.     

医用生物蛋白胶应用于甲状腺次全切除术的意义

目的:探讨医用生物蛋白胶在甲状腺次全切除手术治疗中的作用。方法:2003年10月至2005年12月甲状腺次全切手术治疗的186例患者分成两组,其中98例应用生物蛋白胶,不放引流物,另一组组88例放置胶管或胶片引流。两组进行引流量、拆线时间等多项指标对比。结果:第Ⅰ组多指标优于或等于第Ⅱ组。结论:在甲状腺次全切除术应用医用生物蛋白胶后渗血渗液明显减少,可不放引流物,引流物引起的并发症减少。     

Three hours of perfusion culture prior to 28 days of static culture, enhances osteogenesis by human cells in a collagen GAG scaffold

In tissue engineering, bioreactors can be used to aid in the in vitro development of new tissue by providing biochemical and physical regulatory signals to cells and encouraging them to undergo differentiation and/or to produce extracellular matrix prior to in vivo implantation. This study examined the effect of short term flow perfusion bioreactor culture, prior to long‐term static culture, on human osteoblast cell distribution and osteogenesis within a collagen glycosaminoglycan (CG) scaffold for bone tissue engineering. Human fetal osteoblasts (hFOB 1.19) were seeded onto CG scaffolds and pre‐cultured for 6 days. Constructs were then placed into the bioreactor and exposed to 3 × 1 h bouts of steady flow (1 mL/min) separated by 7 h of no flow over a 24‐h period. The constructs were then cultured under static osteogenic conditions for up to 28 days. Results show that the bioreactor and static culture control groups displayed similar cell numbers and metabolic activity. Histologically, however, peripheral cell‐encapsulation was observed in the static controls, whereas, improved migration and homogenous cell distribution was seen in the bioreactor groups. Gene expression analysis showed that all osteogenic markers investigated displayed greater levels of expression in the bioreactor groups compared to static controls. While static groups showed increased mineral deposition; mechanical testing revealed that there was no difference in the compressive modulus between bioreactor and static groups. In conclusion, a flow perfusion bioreactor improved construct homogeneity by preventing peripheral encapsulation whilst also providing an enhanced osteogenic phenotype over static controls. Bioeng. 2011; 108:1203–1210. © 2010 Wiley Periodicals, Inc.     

Ion-conformational interaction and charge transport through channels of biological membranes

This work proposes a theory of charge transport through channels in biological membranes, based on ion flow interaction with charged groups of protein macromolecules that form the channel. Displacements of the groups are due to conformational changes of the protein molecule, the relaxation times of which are much larger than the average time of ion ocurrence in the channel. Ion flow is assumed to depend on the conformational changes and vice-versa. The resulting self-organizing ion-conformational system is described by a set of nonlinear differential equations for conformational variables and average occupancy of the channel by ions. The system exhibits multistable behaviour in a certain range of control parameters (potential difference, input ion flow). The stationary states of the system may be identified with the states of discrete conductivity of the ionic channels.     

Comparative landscape genetics and the adaptive radiation of Darwin's finches: the role of peripheral isolation

We use genetic divergence at 16 microsatellite loci to investigate how geographical features of the Galápagos landscape structure island populations of Darwin's finches. We compare the three most genetically divergent groups of Darwin's finches comprising morphologically and ecologically similar allopatric populations: the cactus finches (Geospiza scandens and Geospiza conirostris), the sharp-beaked ground finches (Geospiza difficilis) and the warbler finches (Certhidea olivacea and Certhidea fusca). Evidence of reduced genetic diversity due to drift was limited to warbler finches on small, peripheral islands. Evidence of low levels of recent interisland migration was widespread throughout all three groups. The hypothesis of distance-limited dispersal received the strongest support in cactus and sharp-beaked ground finches as evidenced by patterns of isolation by distance, while warbler finches showed a weaker relationship. Support for the hypothesis that gene flow constrains morphological divergence was only found in one of eight comparisons within these groups. Among warbler finches, genetic divergence was relatively high while phenotypic divergence was low, implicating stabilizing selection rather than constraint due to gene flow. We conclude that the adaptive radiation of Darwin's finches has occurred in the presence of ongoing but low levels of gene flow caused by distance-dependent interisland dispersal. Gene flow does not constrain phenotypic divergence, but may augment genetic variation and facilitate evolution due to natural selection. Both microsatellites and mtDNA agree in that subsets of peripheral populations of two older groups are genetically more similar to other species that underwent dramatic morphological change. The apparent decoupling of morphological and molecular evolution may be accounted for by a modification of Lack's two-stage model of speciation: relative ecological stasis in allopatry followed by secondary contact, ecological interactions and asymmetric phenotypic divergence.     

Male-mediated gene flow in patrilocal primates

Background

Many group–living species display strong sex biases in dispersal tendencies. However, gene flow mediated by apparently philopatric sex may still occur and potentially alters population structure. In our closest living evolutionary relatives, dispersal of adult males seems to be precluded by high levels of territoriality between males of different groups in chimpanzees, and has only been observed once in bonobos. Still, male–mediated gene flow might occur through rare events such as extra–group matings leading to extra–group paternity (EGP) and female secondary dispersal with offspring, but the extent of this gene flow has not yet been assessed.

Methodology/Principal Findings

Using autosomal microsatellite genotyping of samples from multiple groups of wild western chimpanzees (Pan troglodytes verus) and bonobos (Pan paniscus), we found low genetic differentiation among groups for both males and females. Characterization of Y–chromosome microsatellites revealed levels of genetic differentiation between groups in bonobos almost as high as those reported previously in eastern chimpanzees, but lower levels of differentiation in western chimpanzees. By using simulations to evaluate the patterns of Y–chromosomal variation expected under realistic assumptions of group size, mutation rate and reproductive skew, we demonstrate that the observed presence of multiple and highly divergent Y–haplotypes within western chimpanzee and bonobo groups is best explained by successful male–mediated gene flow.

Conclusions/Significance

The similarity of inferred rates of male–mediated gene flow and published rates of EGP in western chimpanzees suggests this is the most likely mechanism of male–mediated gene flow in this subspecies. In bonobos more data are needed to refine the estimated rate of gene flow. Our findings suggest that dispersal patterns in these closely related species, and particularly for the chimpanzee subspecies, are more variable than previously appreciated. This is consistent with growing recognition of extensive behavioral variation in chimpanzees and bonobos.     

戊巴比妥钠和乌拉坦对超声检测兔肾血流动力学变化的影响探讨

目的比较戊巴比妥钠和乌拉坦两麻醉剂在超声监测兔肾血流动力学变化的影响。方法选用日本大耳白兔24只,随机分组,戊巴比妥钠和乌拉坦麻醉两组,每组12只。采用频谱多普勒检测兔肾各级肾动脉血流参数。结果乌拉坦组各级肾动脉收缩期峰值流速（Vmax）,舒张期最低流速（Vmin）均明显高于戊巴比妥钠组（P〈0.05）,动脉搏动指数（PI）和阻力指数（RI）无明显变化（P〉0.05）。结论为保证超声监测兔肾血流动力学实验数据的准确性,戊巴比妥钠麻醉较乌拉坦麻醉更适合。     

中国人群遗传结构分析

本文根据红细胞血型基因频率,用Harpending和Jenkins(1973)方法计算了中国22个人群间的遗传距离,同时在国内首次运用主坐标分析及其排序方法展示了中华民族的遗传结构,反映出中国东西人群与南北人群间的基因流。     

Cell polarization: mechanical switch for a chemical reaction

Anterior-posterior polarity in the Caenorhabditis elegans zygote depends on two groups of PAR proteins, as well as on cortical flow. Recent work now demonstrates that this polarization results from a transition in a bistable reaction-diffusion system of PAR proteins that is triggered by cortical flow.     

Dopamine-1 receptor stimulation attenuates the vasoconstrictive response to gut ischemia.

The effects of fenoldopam, a dopamine-1 (DA-1) receptor agonist, were studied in two groups of anesthetized dogs before and after induction of splanchnic ischemia by way of hemorrhage. During the first portion of the experiment, both groups received fenoldopam (1.5 microg x kg(-1) x min(-1)) for 45 min followed by a 45-min washout. During the second portion, hemorrhage (10 ml/kg) was induced, followed by no intervention in group I (controls) and restarting of the fenoldopam infusion in group II. Prehemorrhage, fenoldopam increased composite portal blood flow by 33% (P < 0.01). After hemorrhage-induced splanchnic ischemia, fenoldopam restored portal vein blood flow to near baseline, maintained the splanchnic fraction of cardiac output, and attenuated the rise in gut mucosal PCO(2). DA-1 receptor stimulation increased portal blood flow and redistributed blood flow away from the serosal layer in favor of the mucosa during basal conditions and after hemorrhage, suggesting a more concentrated distribution of splanchnic DA-1 receptors within the mucosal layer vasculature. Fenoldopam maintained splanchnic blood flow during hypoperfusion and attenuated the splanchnic vasoconstrictive response to hemorrhage.     

Respiration during exercise in conscious laryngectomized humans

We compared respiratory patterning at rest and during steady cycle exercise at work rates of 30, 60, and 90 W in 7 male chronically laryngectomized subjects and 13 normal controls. Breathing was measured with a pneumotachograph and end-tidal PCO2 by mass spectrometer. Inspired air was humidified and enriched to 35% O2. Peak flow, volume, and times for the inspiratory and expiratory half cycles, time for expiratory flow, minute ventilation, and mean inspiratory flow were computer averaged over at least 40 breaths at rest and during the last 2 min of 5-min periods at each work rate. During the transition from rest to exercise and with increasing work rate in both groups, there was an increase in respiratory rate and depth with selective and progressive shortening of expiratory time; these responses were not significantly different between the two groups, but there was a suggestion that respiratory "drive" as quantitated by mean inspiratory flow may limit in the laryngectomized subjects at high work rates. Time for expiratory flow increased on transition from rest to exercise and then decreased in both groups as the work rate increased; it was shorter in the laryngectomy than control group at all levels. In the laryngectomized subjects there was significantly more breath-by-breath scatter in some variables at rest, but there was no difference during exercise. It is concluded that chronic removal of the larynx and upper airways in mildly hyperoxic conscious humans has only subtle and, therefore, functionally insignificant effects on breathing during moderate exercise. Evidence is provided that the upper airways can modulate expiratory flow but not expiratory time during exercise.     

Dispersal, gene flow, and population structure

The accuracy of gene flow estimates is unknown in most natural populations because direct estimates of dispersal are often not possible. These estimates can be highly imprecise or even biased because population genetic structure reflects more than a simple balance between genetic drift and gene flow. Most of the models used to estimate gene flow also assume very simple patterns of movement. As a result, multiple interpretations of population structure involving contemporary gene flow, departures from equilibrium, and other factors are almost always possible. One way to isolate the relative contribution of gene flow to population genetic differentiation is to utilize comparative methods. Population genetic statistics such as FST, heterozygosity and Nei's D can be compared between species with differing dispersal abilities if these species are otherwise phylogenetically, geographically and demographically comparable. Accordingly, the available literature was searched for all groups that meet these criteria to determine whether broad conclusions regarding the relationships between dispersal, population genetic structure, and gene flow estimates are possible. Allozyme and mtDNA data were summarized for 27 animal groups in which dispersal differences can be characterized. In total, genetic data were obtained for 333 species of vertebrates and invertebrates from terrestrial, freshwater and marine habitats. Across these groups, dispersal ability was consistently related to population structure, with a mean rank correlation of -0.72 between ranked dispersal ability and FST. Gene flow estimates derived from private alleles were also correlated with dispersal ability, but were less widely available. Direct-count heterozygosity and average values of Nei's D showed moderate degrees of correlation with dispersal ability. Thus, despite regional, taxonomic and methodological differences among the groups of species surveyed, available data demonstrate that dispersal makes a measurable contribution to population genetic differentiation in the majority of animal species in nature, and that gene flow estimates are rarely so overwhelmed by population history, departures from equilibrium, or other microevolutionary forces as to be uninformative.     

Regulation of canine skeletal muscle and hindlimb blood flow in acute anemia

Redistribution of blood flow away from resting skeletal muscles does not occur during anemic hypoxia even when whole body oxygen uptake is not maintained. In the present study, the effects of sympathetic nerve stimulation on both skeletal muscle and hindlimb blood flow were studied prior to and during anemia in anesthetized, paralyzed, and ventilated dogs. In one series (skeletal muscle group, n = 8) paw blood flow was excluded by placing a tourniquet around the ankle; in a second series (hindlimb group, n = 8) no tourniquet was placed at the ankle. The distal end of the transected left sciatic nerve was stimulated to produce a maximal vasoconstrictor response for 4-min intervals at normal hematocrit (Hct.) and at 30 min of anemia (Hct. = 14%). Arterial blood pressure and hindlimb or muscle blood flow were measured; resistance and vascular hindrance were calculated. Nerve stimulation decreased blood flow (p less than 0.05) in the hindlimb and muscle groups at normal Hct. Blood flow rose (p less than 0.05) during anemia and was decreased (p less than 0.05) in both groups during nerve stimulation. However, the blood flow values in both groups during nerve stimulation in anemic animals were greater (p less than 0.05) than those at normal Hct. Hindlimb and muscle vascular resistance fell significantly during anemia and nerve stimulation produced a greater increase in vascular resistance at normal Hct. Vascular hindrance in muscle, but not hindlimb, was less during nerve stimulation in anemia than at normal Hct.(ABSTRACT TRUNCATED AT 250 WORDS)     

The ecology of two intermittent streams in Victoria, Australia

1. We compared aquatic macroinvertebrate assemblage composition within and between habitats (pools and riffles) at four sites on two intermittent streams in Victoria, Australia during a drought year followed by a wetter year to see how different spatial and temporal scales influenced patterns of community structure detected by multivariate techniques of ordination and classification. We also examined the fit between faunal groups and ‘flow phases’ characterized by multivariate analyses of physicochemical variables in an earlier paper. 2. Pools contained more taxa and individuals than riffles. At the more temporary site, there was considerable overlap between the faunal composition of pools and riffles, whereas habitat-specific assemblages consistently occurred at the more permanent sites. Most taxa were either tolerant, permanent stream forms able to persist in streams that dry briefly, or facultative species that occur in lotic or lentic habitats. Few species appeared specifically adapted to temporary waters. 3. Within habitats, there were some matches between faunal groups and flow phases, especially with the onset of the ‘diminishing flow’ phase, characterized by rising water temperature and conductivity, and declining pH and dissolved oxygen. However, disjunctions among faunal groups were less marked than those between flow phases, and were absent at an intermediate scale when habitats were pooled within sites. At the broadest scale of analysis (within habitats between sites and years), historical events (e.g. whether pools upstream dried completely during the previous summer) apparently influenced community composition as much as site-specific abiotic differences.