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91.
When acutely transferred to diluted seawater (SW), Procephalothrix spiralis and Clitellio arenarius regulate water content (g H2O/g solute free dry wt = s.f.d.w.) via loss of Na and Cl (µmoles/g.s.f.d.w.). The present study extends these observations to a greater range of salinities and determines the effects of long-term, stepwise acclimation to diluted seawaters. Final exposure to a given experimental seawater (70, 50, 30, 15%) was 48 hours. Osmolality (mOsm/kg H2O) and Na, K, and Cl ion concentrations (mEq/l) were determined in total tissue water and in the extracellular fluid of C. arenarius. Extracellular volume was determined as the 14C-polyethylene glycol space. Both species behaved as hyperosmotic conformers in diluted seawaters. However, reduction of the osmotic gradient between worm and medium occurred in P. spiralis, but not C. arenarius, in 30 and 15% SW. In both species, osmolality and Na, Cl, and K concentrations in total tissue water decreased with increased dilution of the SW. Water content increased with dilution of the medium but was lower than that which would be predicted based on approximation of the van't Hoff relation. This indicated the occurrence of regulatory volume decrease (RVD). In P. spiralis, in 70 or 50% SW, RVD was accompanied by loss of Na and Cl contents. However, in 30 or 15% SW, Na and Cl contents increased and in worms in 15% SW K content decreased. The latter movements of Na, Cl and K are indicative of cellular hysteresis and were associated with decreased viability, indicating the lower limits of regulatory ability in this species. In comparison, RVD in C. arenarius occurred in all diluted seawaters and was accompanied by loss of Na and Cl contents. In C. arenarius, evidence for reduced viability was absent. Removal of the supra- and subesophageal ganglia of C. arenarius resulted in retention of water, Na and Cl (g H2O or µmoles/g s.f.d.w.) in worms acclimated to 70% SW. Removal of the cerebral ganglia and cephalic glands of P. spiralis did not significantly influence regulation of water content. 相似文献
92.
Gender difference in the relationship of performance in the handgrip and standing long jump tests to lean limb volume in young adults 总被引:1,自引:0,他引:1
B. N. Davies Elizabeth J. Greenwood S. R. Jones 《European journal of applied physiology and occupational physiology》1988,58(3):315-320
Groups of young, adult males and females performed the handgrip and standing long jump tests. Their total forearm and leg volumes were calculated from a series of circumference and length measurements, and the lean volumes (bone + muscle) calculated by taking the skinfold thickness into consideration. In the handgrip, the mean female performance was 298 N compared with 496 N for the males. In the standing long jump, mean performance expressed as distance x body mass was 87.3 kg.m for females compared with 137.7 kg.m for males. These superior performances of males could simply reflect their greater muscle mass, as the mean lean volumes of female and male limbs respectively were 0.54 l and 0.89 l for forearms, and 11.82 l and 14.82 l for the two legs. However, when the performances of males and females were grouped by lean limb volume, it was found that while in both tests there were linear relationships, males and females did not share a common line. In both tests the male relationship was at a higher level than the female; therefore, for a given lean volume, the male performance was significantly superior to that of the female. The gender difference found in this study has not been seen in other studies in which the performance of skeletal muscle has been related to the cross-sectional area of the active muscles and the possible reasons for the differences are considered. 相似文献
93.
基于随机效应的兴安落叶松材积生长模拟 总被引:1,自引:0,他引:1
基于黑龙江省带岭林业局大青川林场80株人工兴安落叶松解析木数据和Logistic生长模型,分别考虑单木效应和样地效应,利用S-PLUS软件中的NLME过程拟合非线性材积生长模型,采用赤池信息准则(AIC)、贝叶斯信息准则(BIC)、对数似然值和似然比检验等模型评价指标对不同模型的精度进行比较.结果表明:当考虑单木效应影响时,b1、b2、b3(分别代表Logistic模型中的渐进、尺度和形状的随机参数)同时作为随机参数时模型拟合效果最好; 当考虑样地效应影响时,b1作为随机参数时模型拟合效果最好.基于单木效应和样地效应的混合模型的拟合精度高于基本模型(Logistic生长模型),考虑单木效应影响的混合模型的精度高于考虑样地效应影响的模型.模型检验结果表明,随机效应模型不但能反映单木材积的总体平均变化趋势,还能反映个体之间的差异;随机效应模型通过校正随机参数值能提高模型的预测精度. 相似文献
94.
95.
96.
Hans-H. Trepte 《Journal of insect physiology》1979,25(2):199-203
At 21°C the first egg generation takes 6 days to develop. During this period the oöcyte volume increases by a factor of ×5000, and compared with an oögonium the growth factor amounts to ×100,000. The growth rate of the oöcyte increases with each stage of oögenesis, until at stage 5 it reaches 2.5 × 106 μm3/hr. About 35% of the substance stored in the oöcyte originates from the nurse chamber. 30% of the volume is formed in the stage where the oöcyte synthesizes almost exclusively glycogen. Accordingly, about 30% of the volume is provided by the euplasmatic protein synthesis and by the yolk uptake. 相似文献
97.
Gerhard H. Schmidt Kamal S. A. Othman 《Archives of insect biochemistry and physiology》1993,24(1):45-54
In Aiolopus thalassinus (Fabr.), the changes in the volume of the corpora allata (CA), in the concentration of juvenile hormone III (JH III) in the hemolymph, and in protein content in the terminal (t) oocytes were studied during the first gonadotropic cycle. These parameters could be better related to the volume of t-oocytes than to age after emergence. The JH III titer curve was maximum (2.9 pmol/10 μl) at an oocyte volume of 1.2 mm3. Before oviposition (days 10–16) the JH III titer decreased to 0.65 pmol/10 μl hemolyph. The increase in JH III titer reflected a period of high protein storage in the t-oocytes. The largest volume of the CA was reached at the beginning of yolk storage in the t-oocytes. The highest JH III titer did not correspond with the largest volume of CA, which occurred much earlier. © 1993 Wiley-Liss, Inc. 相似文献
98.
Kinetic modeling of [18F]VAT,a novel radioligand for positron emission tomography imaging vesicular acetylcholine transporter in non‐human primate brain 下载免费PDF全文
Hongjun Jin Xuyi Yue Hui Liu Junbin Han Hubert Flores Yi Su Stanley M. Parsons Joel S. Perlmutter Zhude Tu 《Journal of neurochemistry》2018,144(6):791-804
99.
We have previously shown that human interferon α-2b (IFN) produced in Escherichia coli (E. coli) is heterogeneous at the N-terminal, with three major species (Ahsan et al., 2014). These are: (a) the direct translation product of the gene retaining the N-terminal methionine, (b) a species from which the methionyl residue has been removed by E. coli methionyl aminopeptidase to give the native interferon α-2b and (c) in which the N-terminal Cys residue of the latter contains an acetyl group. In this paper we overcome this heterogeneity, using engineered interferon derivatives with phenylalanine residue directly downstream of the N-terminal methionine (Met-Phe-IFN). This modification not only prevented the removal of the N-terminal methionine by E. coli methionyl aminopeptidase but also the subsequent N-acetylation. Critically, Met-Phe-IFN had enhanced activity in a biological assay. N-terminal stabilization was also achieved by fusing human cytochrome b5 at the N-terminal of interferon (b5-IFN-chimera). In this case also, the protein was more active than a reciprocal chimera with cytochrome b5 at the C-terminal of interferon (Met-IFN-b5-chimera). This latter protein also had a heterogeneous N-terminal but addition of phenylalanine following Met, (Met-Phe-IFN-b5-chimera), resolved this problem and gave enhanced biological activity. 相似文献
100.
目的:探讨基于CT血管成像的血流储备分数对肺癌淋巴结转移的诊断价值。方法:2018年1月到11月选择在本院进行诊治的肺癌患者60例,所有患者都给予常规CT检查与CT血管成像,记录成像特征与相关血流储备分数-血流量(blood flow,BF)、血容量(blood volume,BV)、平均通过时间(mean transit time,MTT),判断诊断价值。结果:在60例患者中,病理确诊为淋巴结转移20例,非淋巴结转移40例。转移组的毛刺征、分叶征、棘突征、空泡征等CT征象发生率显著高于非转移组(P0.05)。转移组的肺动脉BF、BV值显著低于非转移组(P0.05),MTT值显著高于非转移组(P0.05)。在60例患者中,Spearman相关分析显示淋巴结转移与MTT成显著正相关性(P0.05),与BF、BV值成显著负相关性(P0.05)。结论:CT血管成像在肺癌中的应用能反映患者的血流储备分数状况,有利于判断患者的淋巴结转移情况,有很好的应用价值。 相似文献