在中国应用垂直波束雷达监测褐飞虱和其他水稻害虫迁飞的可行性

近年来,可用于昆虫迁飞研究且可自动运行的垂直波束雷达(vertical-looking radar,VLR)的发展使得对迁飞性害虫的周年长期自动监测成为可能。本文提供了我们对能否将这种雷达应用于中国的褐飞虱和其他水稻害虫的监测与预测体系以改善其综合治理的可行性研究结果。以往的研究已经表明,这些害虫一般在300—2000m高度迁飞;而我们根据褐飞虱的雷达和射有效截面的计算结果表明,目前使用的3．2cm波长的VLR对褐飞虱个体目标的最大可检测高度仅约240m;虽然建造一部8．8mm波长的VLR即可覆盖褐飞虱迁飞高度的绝大部分,但其造价和维护费用均过于昂贵。为此,一个更可行的解决方案是,以3．2cm波长的VLR作为包括大多数水稻害虫在内的个体较大的迁飞性害虫的监测工具。     

Evolution of duplicate genes in a tetraploid animal, Xenopus laevis

To understand the evolution of duplicate genes, we compared rates of nucleotide substitution between 17 pairs of nonallelic duplicated genes in the tetraploid frog Xenopus laevis with rates between the orthologous loci of human and rodent. For all duplicated X. laevis genes, the number of synonymous substitutions per site (dS) was greater than the number of nonsynonymous substitutions per site (dN), indicating that these genes are subject to purifying selection. There was also a significant positive correlation (r = 0.915) between dN for the X. laevis genes and dN for the mammalian genes, suggesting that, at the amino acid level, the X. laevis genes and the mammalian genes are under similar constraints. Results of relative-rate tests showed nearly equal rates of nonsynonymous substitution in each copy of the X. laevis genes; apparently there are similar constraints on both copies. No correlation was found between dS for the X. laevis genes and dS for the mammalian genes. There was a significant positive correlation both between members of pairs of duplicated X. laevis genes (r = 0.951) and between human and rodent orthologues (r = 0.854) with respect to third- position G+C content but no such relationship between the X. laevis genes and either of their mammalian orthologues. The results indicate that both copies of a duplicate gene can be subject to purifying selection and thus support the hypothesis of selection against all genotypes containing a null allele at either of two duplicate loci.      

Cell surface distribution and intracellular fate of asialoglycoproteins: a morphological and biochemical study of isolated rat hepatocytes and monolayer cultures

A combination of biochemistry and morphology was used to demonstrate that more than 95 percent of the isolated rat hepatocytes prepared by collagenase dissociation of rat livers retained the pathway for receptor-mediated endocytosis of asialoglycoproteins (ASGPs). Maximal specific binding of (125)I-asialoorosomucoid ((125)I-ASOR) to dissociated hepatocytes at 5 degrees C (at which temperature no internalization occurred) averaged 100,000-400,000 molecules per cell. Binding, uptake, and degredation of (125)I- ASOR at 37 degrees C occurred at a rate of 1 x 10(6) molecules per cell over 2 h. Light and electron microscopic autoradiography (LM- and EM-ARG) of (125)I-ASOR were used to visualize the surface binding sites at 5 degrees C and the intracellular pathway at 37 degrees C. In the EM-ARG experiments, ARG grains corresponding to (125)I-ASOR were distributed randomly over the cell surface at 5 degrees C but over time at 37 degrees C were concentrated in the lysosome region. Cytochemical detection of an ASOR-horseradish peroxidase conjugate (ASOR-HRP) at the ultrastructural level revealed that at 5 degrees C this specific ASGP tracer was concentrated in pits at the cell surface as well as diffusely distributed along the rest of the plasma membrane. Such a result indicates that redistribution of ASGP surface receptors had occurred. Because the number of surface binding sites of (125)I-ASOR varied among cell preparations, the effect of collagenase on (125)I-ASOR binding was examined. When collagenase-dissociated hepatocytes were re-exposed to collagenase at 37 degrees C, 10-50 percent of control binding was observed. However, by measuring the extent of (125)I-ASOR binding at 5 degrees C in the same cell population before and after collagenase dissociation, little reduction in the number of ASGP surface receptors was found. Therefore, the possibility that the time and temperature of the cell isolations allowed recovery of cell surface receptors following collagenase exposure was tested. Freshly isolated cells, dissociated cells that were re-exposed to collagenase, and perfused livers exposed to collagenase without a Ca(++)-free pre-perfusion, were found to bind 110-240 percent more(125)I-ASOR after 1 h at 37 degrees C that they did at 0 time. This recovery of surface ASGP binding activity occurred in the absence of significant protein synthesis (i.e., basal medium or 1 mM cycloheximide). Suspensions of isolated, unpolarized hepatocytes were placed in monolayer culture for 24 h and confluent cells were demonstrated to reestablish morphologically distinct plasma membrane regions analogous to bile canalicular, lateral, and sinusoidal surfaces in vivo. More than 95 percent of these cells maintained the capacity to bind, internalize, and degrade (125)I-ASOR at levels comparable to those of the freshly isolated population. ASOR-HRP (at 5 degrees C) was specifically bound to all plasma membrane surfaces of repolarized hepatocytes (cultured for 24 h) except those lining bile canalicular-like spaces. Thus, both isolated, unpolarized hepatocytes and cells cultured under conditions that promote morphological reestablishment of polarity maintain the pathway for receptor- mediated endocytosis of ASGPs.     

Golden hamster perivitelline spermatozoa do not show proacrosin/acrosin at the inner acrosomal membrane.

It has been suggested that acrosin may function in penetration of the zona pellucida and of the highly structured extracellular matrix of the perivitelline space. In this study we investigated whether golden hamster perivitelline spermatozoa contain proacrosin/acrosin, as evidenced by the silver enhanced immunogold technique using the monoclonal antibody antiacrosin C2E5. None of the 197 spermatozoa recovered from the perivitelline space showed proacrosin/acrosin associated with the acrosomal region, suggesting that acrosin would not play a role in the penetration of the perivitelline extracellular matrix.     

Hip joint replacement surgery for idiopathic osteoarthritis aggregates in families

In order to determine whether there is a genetic component to hip or knee joint failure due to idiopathic osteoarthritis (OA), we invited patients (probands) undergoing hip or knee arthroplasty for management of idiopathic OA to provide detailed family histories regarding the prevalence of idiopathic OA requiring joint replacement in their siblings. We also invited their spouses to provide detailed family histories about their siblings to serve as a control group. In the probands, we confirmed the diagnosis of idiopathic OA using American College of Rheumatology criteria. The cohorts included the siblings of 635 probands undergoing total hip replacement, the siblings of 486 probands undergoing total knee replacement, and the siblings of 787 spouses. We compared the prevalence of arthroplasty for idiopathic OA among the siblings of the probands with that among the siblings of the spouses, and we used logistic regression to identify independent risk factors for hip and knee arthroplasty in the siblings. Familial aggregation for hip arthroplasty, but not for knee arthroplasty, was observed after controlling for age and sex, suggesting a genetic contribution to end-stage hip OA but not to end-stage knee OA. We conclude that attempts to identify genes that predispose to idiopathic OA resulting in joint failure are more likely to be successful in patients with hip OA than in those with knee OA.     

Resynchronization of ovulation and timed insemination in lactating dairy cows, II: assigning protocols according to stages of the estrous cycle, or presence of ovarian cysts or anestrus

Pregnancy rates were compared in lactating dairy cows (n = 1083) assigned to protocols for resynchronization of ovulation based on stages of the estrous cycle, or presence of ovarian cysts or anestrus. Cows were detected not pregnant by ultrasonography 30 d after a previous AI (study day 0) and classified as diestrus, metestrus, proestrus, with ovarian cysts or anestrus. Cows in diestrus (January-May) were assigned to either Ovsynch (GnRH day 0, PGF2alpha day 7, GnRH day 9, and timed-AI [TAI] 16 h later; n = 96), or Quicksynch (PGF2alpha day 0, estradiol cypionate [ECP] day 1, AI at detected estrus [AIDE] on day 2, or TAI on day 3; n = 96). Cows in diestrus (June-December) were assigned to either Ovsynch (n = 156) or Modified Quicksynch (PGF2alpha day 0, ECP day 1, AIDE days 2 and 3, and to Ovsynch on day 4 if not detected in estrus; n = 142). Cows in metestrus were assigned either to Ovsynch (n = 68), Heatsynch (GnRH day 0, PGF2alpha day 7, ECP day 8, AIDE day 9, or TAI day 10; n = 62), or GnRH + Ovsynch (GnRH on day 0, followed by Ovsynch on day 8; n = 64). Cows in proestrus, with ovarian cysts, or anestrus were assigned to either Ovsynch (proestrus n = 89, ovarian cysts n = 97, anestrus n = 8) or GnRH + Ovsynch (proestrus n = 87, ovarian cysts n = 109, anestrus n = 9). Pregnancy rate was evaluated 30, 55 and 90 d after resynchronized AI. For cows in diestrus (January-May), pregnancy rates were higher for Ovsynch (35.9, 29.2 and 26.0%) than for Quicksynch (21.7, 16.7 and 15.6%). For cows in diestrus (June-December), pregnancy rates were similar for Ovsynch (34.4, 24.0 and 23.6%) and Modified Quicksynch (27.1, 26.2 and 21.6%). For cows in metestrus, pregnancy rates were higher for GnRH + Ovsynch (33.3, 24.5 and 20.3%) than for Heatsynch (20.3, 12.9 and 9.8%). For cows with ovarian cysts, pregnancy rates were higher for GnRH + Ovsynch (30.3, 26.6 and 22.9%) than for Ovsynch (20.2, 18.5 and 14.7%). Assignment to resynchronization protocols based on the stages of the estrous cycle, or presence of ovarian cysts improved pregnancy rates.     

Anaphylatoxin signaling in human neutrophils. A key role for sphingosine kinase

Anaphylatoxins activate immune cells to trigger the release of proinflammatory mediators that can lead to the pathology of several immune-inflammatory diseases. However, the intracellular signaling pathways triggered by anaphylatoxins are not well understood. Here we report for the first time that sphingosine kinase (SPHK) plays a key role in C5a-triggered signaling, leading to physiological responses of human neutrophils. We demonstrate that C5a rapidly stimulates SPHK activity in neutrophils and differentiated HL-60 cells. Using the SPHK inhibitor N,N-dimethylsphingosine (DMS), we show that inhibition of SPHK abolishes the Ca2+ release from internal stores without inhibiting phospholipase C or protein kinase C activation triggered by C5a but has no effect on calcium signals triggered by other stimuli (FcgammaRII). We also show that DMS inhibits degranulation, activation of the NADPH oxidase, and chemotaxis triggered by C5a. Moreover, an antisense oligonucleotide against SPHK1, in neutrophil-differentiated HL-60 cells, had similar inhibitory properties as DMS, suggesting that the SPHK utilized by C5a is SPHK1. Our data indicate that C5a stimulation decreases cellular sphingosine levels and increases the formation of sphingosine-1-phosphate. Exogenously added sphingosine has a dual effect on C5a-stimulated oxidative burst: it has a priming effect at lower concentrations but a dose-dependent inhibitory effect at higher concentrations; however, C5a-triggered protein kinase C activity was only reduced at high concentration of sphingosine. In contrast, C5a-triggered Ca2+ signals, chemotaxis, and degranulation were not affected by sphingosine at all. Exogenous sphingosine-1-phosphate, by itself, did not induce degranulation or chemotaxis, but it did marginally induce Ca2+ signals and oxidative burst and had a priming effect, enhancing all the C5a-triggered responses. Taken together, these results suggest that SPHK plays an important role in the immune-inflammatory pathologies triggered by anaphylatoxins in human neutrophils and point out SPHK as a potential therapeutic target for the treatment of diseases associated with neutrophil hyperactivation.