Seasonal changes in fast-starts in the short-horn sculpin: integration of swimming behaviour and muscle performance

In short-horn sculpin Myoxocephalus scorpius , the power requirements for fast-start swimming and the length-specific velocity of the curvature wave travelling down the spine ( Û ) were not influenced significantly by acclimation to summer and winter conditions at test temperatures of 5 and 15° C. However, in-vivo and in-vitro muscle performance exhibited acclimation responses at 15° C. Seasonal acclimation altered the escape performance curves for power and Û significantly over a wider temperature range of 0·8–20° C. Û was significantly higher at 20° C in the summer- than winter-acclimation group. The acclimation of lower levels of physiological organization at 15° C may thus serve to extend the thermal limits for escape performance in summer acclimated fish.     

Size-dependence of reproductive allocation of Sargassum thunbergii (Sargassaceae, Phaeophyta) in Bohai Bay, China

Reproductive allocation (the proportion of biomass allocated to reproductive tissue, RA) in Sargassum thunbergii was studied in Yantai, Shandong Peninsula, southern coast of Bohai Bay, China. Annual reproduction initiated in mid-June and peaked in mid-July (90 ± 8% fertile thalli and 75 ± 6% RA mean). Both RA and percentage of fertile thalli exhibited significant temporal variations during reproduction. Sterile thalli were only observed in small length hierarchies at peak reproduction and mean values of RA showed a significantly hierarchical variation, suggesting that the size of thalli played an important role in reproduction and RA were size-dependent. Numerous receptacles were produced along the lateral branches during the reproductive period. A distinct seasonal pattern was observed wherein the presence of lateral branches was followed by the onset of reproduction. RA was positively correlated with the number of lateral branches, as well as the total length of lateral branches. In addition, fertile thalli decayed quickly after peak reproduction. The probability of decay was evidently higher for fertile than for sterile thalli, because all surviving thalli were sterile and short during July–August. So, a trade-off between reproduction and survival may exist at individual levels in S. thunbergii.     

Species identity of geographically distinct populations of the glassy-winged sharpshooter parasitoid Gonatocerus ashmeadi: morphology, DNA sequences, and reproductive compatibility

Gonatocerus ashmeadi is a common and seemingly widespread egg parasitoid of Homalodisca coagulata, the glassy-winged sharpshooter (GWSS). Location records for G. ashmeadi indicate its natural range to be the southeastern USA and northeastern Mexico (which coincides with the presumed native range of GWSS), and possibly southern and central California (CA) (the adventive range of GWSS). The purpose of our work was to determine whether G. ashmeadi in the USA and northeastern Mexico is one species or a complex of reproductively incompatible sibling species. We used three approaches to determine the species identity of different G. ashmeadi populations: (1) reassessment of key morphological features using scanning electron microscopy (SEM) to determine if subtle morphological differences exist between G. ashmeadi populations which could indicate species differences; (2) to determine if molecular differences exist between G. ashmeadi populations collected from different regions by comparing mitochondrial and ribosomal DNA sequences; (3) mating compatibility studies to determine if different populations of G. ashmeadi are reproductively isolated, or if mating occurs, whether offspring are viable thereby defining species groups on the basis of successful interbreeding. Results from these three areas (morphology, DNA sequences, and reproductive compatibility) have been evaluated collectively; leading us to the conclusion that G. ashmeadi as it is currently viewed is a valid species and not an aggregate of morphologically indistinguishable cryptic species.     

女性体检人群生殖道病原体的分布

目的了解体检妇女人群生殖道感染情况,为女性生殖道感染的防治提供进一步的资料。方法对1157例参加健康体检的妇女的阴道后穹窿及宫颈分泌物标本进行显微镜镜检以检测阴道清洁度、真菌、滴虫等,同时采用培养法对淋球菌、解脲支原体、人型支原体、真菌等进行检测,沙眼衣原体则采用免疫层析法;检测结果进行统计学分析。结果女性生殖道感染的感染率为54.0%,其中混合感染率为9.3%,而清洁度异常率仅为23.8%;前3位病原体依次为解脲支原体(35.3%)、衣原体(22.2%)、真菌(5.5%);年轻妇女组与年老组支原体的检出率差异有显著性(P<0.05)。结论女性生殖道感染情况严重,支原体、衣原体等感染隐匿,加强对育龄妇女的监测尤为重要。     

PRRSV NJ-a株ORF5基因A表位的修饰与糖基化位点的突变对其DNA疫苗免疫效力的影响

为了提高PRRSV ORF5基因的免疫效力,对ORF5基因进行了改造,将CpG序列和通用型辅助性T淋巴细胞表位插入A表位与B表位之间,并对N33与N51位糖基化位点进行了点突变,获得改造的ORF5基因。在此基础上构建了由两个CMV启动子调控的共表达改造的ORF5(MORF5)与ORF6基因的真核表达质粒pcDNA-M5A-6A。经Western-blot与IFA验证真核质粒的体外表达后,免疫6周龄Balb/c小鼠,利用微量中和试验检测免疫后的中和抗体,利用MTT法检测免疫后淋巴细胞的增生情况,并与未改造ORF5基因真核表达质粒pcDNA-5A-6A、弱毒疫苗以及灭活疫苗的免疫效果进行比较。结果表明,pcDNA-M5A-6A不但能够刺激免疫小鼠在较短的时间内产生更高水平的中和抗体,而且可以诱导产生更强烈的T淋巴细胞增殖反应。所构建的共表达PRRSV改造的ORF5基因与ORF6基因的DNA疫苗pcDNA-M5A-6A,能够较好的诱发小鼠产生较高的特异性针对PRRSV的中和抗体和细胞免疫应答,为研究能够更好地防制PRRSV的新型疫苗提供了新的思路。     

Hosts feeding only Brown‐headed Cowbird fledglings: where are the host fledglings?

ABSTRACT.   Brown-headed Cowbirds ( Molothrus ater ) impose costs on their hosts, usually resulting in fewer or no host young being raised. In 95% of the studies where attempts were made to estimate the cost of parasitism, cost was measured as the difference in host nestling survival in parasitized and unparasitized nests. For hosts that fledge at least some of their own young along with cowbirds, the magnitude of further brood reduction beyond the nestling stage is not known. To examine the possibility that further brood reduction occurs during the fledgling stage, we compiled 102 observations of 45 species feeding fledgling cowbirds. In 97 cases, observers did not record hosts feeding their own young, suggesting that many young die shortly after fledging from parasitized nests. These observations suggest that measuring the cost of parasitism as the difference between the number of host young fledged from parasitized and unparasitized nests probably overestimates the reproductive output of many hosts. If costs increase during the fledgling stage, then the costs of brood parasitism have been underestimated in many studies.     

Swimming performance of silver eels is severely impaired by the swim-bladder parasite Anguillicola crassus

Infection with the swim-bladder parasite Anguillicola crassus is suggested as one of the principal causes of the collapse of the European eel population. This nematode has been introduced in Europe from Asia in the 80s and parasitized in a short time Anguilla eel species in different geographical regions across the globe. The parasites drain energy due to their sanguivorous feeding and they cause mechanical damage on the swim-bladder wall. These two effects are hypothesized to impair the spawning migration of the European eel. In this study, we have investigated both effects on swimming performance. We hypothesized that parasitic sanguivorous activities - related to parasite weight - reduce swimming endurance, while mechanical damage of the swim-bladder impairs buoyancy control. Eighty eels suffering various degrees of infection were introduced in swim-tunnels and subjected to a swimming fitness test. The relation between A. crassus infection and swimming efficiency was measured for large female silver eels swimming at various speeds. Infected eels had lower cruising speeds and a higher cost of transport. Eels without parasites, but with a damaged swim-bladder showed similar effects. Almost half of the eels that contained damaged swim-bladders (43%) stopped swimming at low aerobic swimming speeds (< 0.7 m/s). Simulated migration trials in a recent related study have confirmed that eels with a high parasite level or with damaged swim-bladder show early migration failure (< 1000-km). Reduced swimming performance appears to be associated with swim-bladder dysfunction. As we found that especially silver eels have much higher infection levels than yellow eels, it is concluded that migrating silver eels with severely infected or damaged swim-bladders are unable to reach the spawning grounds.     

Reproductive parameters of female Japanese macaques: Thirty years data from the arashiyama troops,Japan

Over a 30-year period from 1954 to 1983, 975 live births were recorded for Japanese macaque females at the Iwatayama Monkey Park, Arashiyama, Japan. Excluding unknown birth dates, primiparous mothers gave birth to 185 infants (182 cases with age of mother known) and multiparous mothers gave birth to 723 infants (603 cases with age of mother known). The peak month of birth was May with 52.3% of the total births occurring during the period. Multiparous females who had not given birth the previous year did so earlier than multiparous females who had given birth the previous year and also earlier than primiparous females. Among the females who had given birth the previous year, females whose infant had died gave birth earlier than females who had reared an infant the previous year. The offspring sex ratio (1:0.97) was not significantly different from 1:1, and revealed no consistent association with mother's age. Age-fecundity exhibited a humped curve. The annual birth rate was low at the age of 4 years but increased thereafter, ranging between 46.7% and 69.0%, at between 5 and 19 years of age, but again decreased for females between 20 and 25 years of age. Some old females displayed clear reproductive senescence. The infant mortality within the first year of age was quite low (10.3%) and the neonatal (less than 1 month old) mortality rate accounted for 49.0% of all infant deaths. There was no significant difference between the mortality rates of male and female infants. A female's rank-class had no apparent effect on the annual birth rate, infant mortality, and offspring sex ratio. These long-term data are compared with those from other primate populations.     

南亚热带季风常绿阔叶林水文功能及其养分动态的研究

 根据在鼎湖山季风常绿阔叶林集水区3年的观测结果,对这一南亚热带地带性植被的水文功能进行了较深入的探讨。由于林分结构复杂,季风常绿阔叶林对大气降水具有较高的林冠截留率,截留率的季节变化动态与降水量的季节分配有关。该森林土壤结构良好,其渗水速度快,加上有较厚的枯落物层,对于减缓地面径流,减少水土流失,功效甚大。但由于土层较薄,其蓄水功能有限。该森林的径流量占总降水量的比例特别是地表径流所占比例较小,分别为50.22％和14.19％。其季节分配有利于保持水土和植物生长。由于土壤蓄水量变化出现负值,用水量平衡法计算得出鼎湖山季风常绿阔叶林年蒸发散量为1323.98mm,占大气降水量的51.81％。该森林的降水中主要营养元素浓度较高,降水带来大量的养分,特别是氮素的年输入量高达35.29kg·hm-2。淋溶也给该森林带来较高的养分归还量,其中钾的淋溶量高达35.65kg·hm-2;镁的淋溶量高达8.9kg·hm-2,为林外雨输入的2.37倍。径流中的氮输出为28.35kg·hm-2,降水中的氮素净输入量为6.94kg·hm-2;但镁的净输入呈负值。     

Production-dependent reproductive allocation of a tall tree speciesQuercus serrata

The reproductive allocation (allocation of net production to acorns) of a tall tree speciesQuercus serrata was estimated by a method combining branch diameter distribution and the sampling of acorns per branch. Acorn production per branch of 0.5-cm diameter significantly varied among individuals and years, but not significantly across tree size. Leaf production per branch of 0.5-cm diameter had little annual fluctuation, while that of acorns fluctuated about 6 times between the maximum and minimum. The reproductive allocation was regressed against vegetative allocation, following the general model of klinkhameret al. (1992); the reproduction had a beginning threshold and reproductive allocation increased drastically at relatively young stage after the tree began reproduction. With its small threshold production, coppicing traits and large maximum size,Q. serrata seemed adaptive to infrequent but large-scale disturbances like fires.