Polymorphic microsatellite DNA markers in the mudflat topshell Diloma subrostrata (Gastropoda,Trochidae)

Very little information is available on the intraspecific genetic structure of topshell populations. Here, we report the characterization of five polymorphic microsatellite loci in the New Zealand mudflat topshell, Diloma subrostrata. The number of alleles per locus ranged from two to 23, observed and expected heterozygosities did not deviate from Hardy–Weinberg equilibrium (P < 0.05) and no linkage disequilibrium was detected between locus pairs (P < 0.05). We are currently using these markers to investigate genetic population structure of D. subrostrata in New Zealand.     

Influence of northern limit range on genetic diversity and structure in a widespread North American tree,sugar maple (Acer saccharum Marshall)

Due to climate change, the ranges of many North American tree species are expected to shift northward. Sugar maple (Acer saccharum Marshall) reaches its northern continuous distributional limit in northeastern North America at the transition between boreal mixed‐wood and temperate deciduous forests. We hypothesized that marginal fragmented northern populations from the boreal mixed wood would have a distinct pattern of genetic structure and diversity. We analyzed variation at 18 microsatellite loci from 23 populations distributed along three latitudinal transects (west, central, and east) that encompass the continuous–discontinuous species range. Each transect was divided into two zones, continuous (temperate deciduous) and discontinuous (boreal mixed wood), based on sugar maple stand abundance. Respective positive and negative relationships were found between the distance of each population to the northern limit (D_north), and allelic richness (A_R) and population differentiation (F_ST). These relations were tested for each transect separately; the pattern (discontinuous–continuous) remained significant only for the western transect. structure analysis revealed the presence of four clusters. The most northern populations of each transect were assigned to a distinct group. Asymmetrical gene flow occurred from the southern into the four northernmost populations. Southern populations in Québec may have originated from two different postglacial migration routes. No evidence was found to validate the hypothesis that northern populations were remnants of a larger population that had migrated further north of the species range after the retreat of the ice sheet. The northernmost sugar maple populations possibly originated from long‐distance dispersal.     

A note on comparing exposure data to a regulatory limit in the presence of unexposed and a limit of detection

In some occupational health studies, observations occur in both exposed and unexposed individuals. If the levels of all exposed individuals have been detected, a two-part zero-inflated log-normal model is usually recommended, which assumes that the data has a probability mass at zero for unexposed individuals and a continuous response for values greater than zero for exposed individuals. However, many quantitative exposure measurements are subject to left censoring due to values falling below assay detection limits. A zero-inflated log-normal mixture model is suggested in this situation since unexposed zeros are not distinguishable from those exposed with values below detection limits. In the context of this mixture distribution, the information contributed by values falling below a fixed detection limit is used only to estimate the probability of unexposed. We consider sample size and statistical power calculation when comparing the median of exposed measurements to a regulatory limit. We calculate the required sample size for the data presented in a recent paper comparing the benzene TWA exposure data to a regulatory occupational exposure limit. A simulation study is conducted to investigate the performance of the proposed sample size calculation methods.     

Changes in the behaviour of the sole,Solea vulgaris,during cold winters,and the relation between the winter catch and sea temperatures

Summary 1. Exceptionally large catches of soles are made in the North Sea during very cold winters. It was considered that these catches were due to increased vulnerability of the fish to trawling at low sea temperatures, and to the concentration of fish into smaller areas, of high density, by the cold water masses. A third contributory factor was that the soles remained on the offshore trawling grounds for a longer time in cold winters.2. Data from fishing reports, sole catches in different regions of the southern North Sea, and the positions of recapture of tagged soles in the winter of 1962/63 were used to illustrate the changes in the behaviour of this fish.3. Although soles suffered high mortalities from low temperatures, predation, and from fishing during winter 1962/63, reducing the numbers of potential spawning fish, it was suggested that the failure of the coastal spawning fisheries was also partly due to a large part of the stock failing to migrate inshore in this year.4. It was considered that since soles appear to be particularly sensitive to low temperatures there might be a direct relationship between the winter catches of soles and the sea temperatures. This relationship was investigated and seems to hold good, at least for the post-war years since 1948.

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Veränderungen im Verhalten der SeezungeSolea vulgaris während kalter Winter und die Beziehung zwischen Winterfang und Meertemperaturen

Kurzfassung Während kalter Winter werden ungewöhnlich große Seezungenfänge eingebracht. Diese Tatsache hängt offenbar zusammen mit der durch das kalte Wasser verursachten Ansammlung großer Bestände in relativ kleinen Gebieten, mit der erhöhten Verwundbarkeit durch die Schleppnetzfischerei bei niedrigen Temperaturen sowie mit der längeren Anwesenheit der Seezungen in küstennahen Schleppnetzgründen.Solea vulgaris ist offenbar besonders empfindlich gegenüber niedrigen Temperaturen. Es konnte eine deutliche Beziehung zwischen Winterfangergebnissen und der Wassertemperatur nachgewiesen werden.

     

Insect drift over the northern Arabian sea in early summer

Air borne insects, mostly carried by wind currents, were trapped over the northern Arabian sea (16‡ to 20‡ N; 68‡ to 72‡ E), in the course of cruise No. 111, ORVSAGAR KANYA (March 14 to April 7, 1996). A total of 2,301 insects belonging to 8 different orders, 47 families and 173 species were trapped. Of these, Hymenoptera was represented by the largest number (1082), which was followed by Hemiptera (586), Diptera (552), Coleoptera (51), Neuroptera (10), Trichoptera (03), Lepidoptera (03) and Orthoptera (01). The trapped insects were mostly between 0.6 mm to over 11 mm long. The data was examined for α-diversity as well as for possible correlations between various parameters like the diversity index, size and number of insects trapped on one hand and the distance of the nearest land mass in wind direction, on the other. Deceased.     

Genetic consequences of fragmentation in “arbor vitae,” eastern white cedar (Thuja occidentalis L.), toward the northern limit of its distribution range

We tested the hypothesis that marginal fragmented populations of eastern white cedar (EWC) are genetically isolated due to reduced pollen and gene flow. In accordance with the central-marginal model, we predicted a decrease in population genetic diversity and an increase in differentiation along the latitudinal gradient from the boreal mixed-wood to northern coniferous forest. A total of 24 eastern white cedar populations were sampled along the north-south latitudinal gradient for microsatellite genotyping analysis. Positive F_is values and heterozygote deficiency were observed in populations from the marginal (F_is = 0.244; P_HW = 0.0042) and discontinuous zones (F_is = 0.166; P_HW = 0.0042). However, populations from the continuous zone were in HW equilibrium (F_is = −0.007; P_HW = 0.3625). There were no significant latitudinal effects on gene diversity (H_s), allelic richness (AR), or population differentiation (F_st). Bayesian and NJT (neighbor-joining tree) analyses demonstrated the presence of a population structure that was partly consistent with the geographic origins of the populations. The impact of population fragmentation on the genetic structure of EWC is to create a positive inbreeding coefficient, which was two to three times higher on average than that of a population from the continuous zone. This result indicated a higher occurrence of selfing within fragmented EWC populations coupled with a higher degree of gene exchange among near-neighbor relatives, thereby leading to significant inbreeding. Increased population isolation was apparently not correlated with a detectable effect on genetic diversity. Overall, the fragmented populations of EWC appear well-buffered against effects of inbreeding on genetic erosion.     

Antisense downregulation of the barley limit dextrinase inhibitor modulates starch granule size distribution, starch composition and amylopectin structure

The barley protein limit dextrinase inhibitor (LDI), structurally related to the alpha-amylase/trypsin inhibitor family, is an inhibitor of the starch debranching enzyme limit dextrinase (LD). In order to investigate the function of LDI, and the consequences for starch metabolism of reduced LDI activity, transgenic barley plants designed to downregulate LDI by antisense were generated. Homozygous antisense lines with reduced LDI protein level and activity were analysed and found to have enhanced free LD activity in both developing and germinating grains. In addition the antisense lines showed unpredicted pleiotropic effects on numerous enzyme activities, for example, alpha- and beta-amylases and starch synthases. Analysis of the starch showed much reduced numbers of the small B-type starch granules, as well as reduced amylose relative to amylopectin levels and reduced total starch. The chain length distribution of the amylopectin was modified with less of the longer chains (>25 units) and enhanced number of medium chains (10-15 units). These results suggest an important role for LDI and LD during starch synthesis as well as during starch breakdown.     

新疆北部啮齿动物地理分布的聚类研究

将新疆北部 62种啮齿动物在新疆北部 6个动物地理省中有或无分布作为二元状态 ,用联合系数来表征啮齿动物地理省间啮齿类种类组成的相似程度 ,以类平均法进行聚类。聚类结果表明啮齿类在新疆北部各动物地理省的分布主要受各种生态因子的影响。还探讨了分布聚类与动物地理省区划的关系     

The growth of brown trout (Salmo trutta) in mild winters and summer droughts in upland Wales

SUMMARY. 1. We compared the observed annual growth of 0- and I-group trout in nine Welsh upland streams, with growth predicted from temperature assuming that this was the only limiting factor.
2. Autumn weights of second year fish were 51–67% of predicted ( G _max) values in 1988, but only 30–40% in 1989 and 1990 when drought occurred. Though initial weights of fry were unknown, simulations suggested that first year growth was also less than G _max, but with no obvious effect of drought.
3. To evaluate the possible effects of future climate change, we simulated stream temperature regimes 1.5–4.5°C above those of a recent year with temperatures similar to the long-term average. Growth was set at 60% G _max for both 0- and I-group, or at 40% for I-group to represent the effect of drought. As winter temperature increased, time to hatching and emergence decreased, for example by 56 and 49 days respectively for a rise of 3°C. 0-group growth was slightly enhanced at up to + 3°C but retarded at + 4.5°C. Simulations of I-group growth suggested that warmer winters could enhance trout growth while warmer summers would only increase growth if there were no adverse effects of drought.
4. We discuss many uncertainties in these simulations, which nevertheless suggest the magnitude of possible effects of climate change.     

The northern limit of Pinus banksiana Lamb. in Canada: explaining the difference between the eastern and western distributions

Aim Present northern distribution limit of jack pine (Pinus banksiana Lamb.) follows the northern limit of continuous open boreal forest in western Canada, but not in eastern Canada where it is located further south. We tested the hypothesis that fire plays a more important role than climate in explaining the present position of the northern distribution limit of jack pine. Location An experimental jack pine plantation was set up in 1992, c. 300 km north of the present distribution limit of the species, in the Boniface river area of northern Québec (57°43′ N, 76°05′ W). Methods Climate and fire data were used to compare sites at and north of the present distribution limit of jack pine. In 2001, surviving individuals from the plantation were measured (total height, annual shoot elongation, basal diameter, and presence/absence of cones). Results Climate data from the ten weather stations used in this study did not show major differences. The northern limit of jack pine distribution is closely associated with the occurrence of fires larger than 200 ha. Survival of the planted jack pines was 31%. About 25% of the surviving pines qualified as normal, single‐stem individuals; the others were slightly uprooted and/or showed marks of erosion or foraging. Cones were produced, although no viable seeds were found. Main conclusions The low number of degree‐days above 5 °C at the plantation site could explain why the seeds were not viable. However, such climate conditions are not sufficient to prevent growth, as was shown by annual shoot elongation measurements. Most of the surviving jack pines from the Boniface river plantation are relatively healthy and follow a normal developmental programme. Low fire frequency and small fire size are amongst the main factors that prevented P. banksiana from migrating further north or east following deglaciation in northern Québec and Labrador.     

Seasonal and geographical variation in diapause and cold hardiness of the Asian corn borer,Ostrinia furnacalis

Asian corn borer, Ostrinia furnacalis (Guenée), is a key corn pest in the Asian‐Western Pacific countries. It overwinters as full‐grown larvae in plant stalks or in a spun‐silk covering located in the plant debris in the temperate regions of China. Supercooling point (SCP) and survival rate after low sub‐zero temperature treatment were assessed for field‐collected populations in the laboratory using a cool bath with a 1°C/min cooling rate until ?40°C. Mean SCPs were varied among geographical populations, with a significant decline from ?22.7°C of Haikou, the multivoltine tropical population in the south, to ?28.5°C of Gongzhuling, the univoltine temperate population in the northeast of China. In addition, there was more than 1°C difference in SCP between Gongzhuling univoltine and bivoltine populations that were from the same geographic origin. Mean SCPs of the Guangzhou population fluctuated over the year, with significantly lower SCPs in winter than in other seasons, which correlated with a significantly higher proportion of diapausing larvae in winter than in other seasons. Over 41% of overwintering larvae from the northeast population could withstand to be supercooled for a few minutes to the low sub‐zero temperature of ?40°C, but only 6.7% of their southern counterparts did so. The findings from this study suggest that O. furnacalis mostly takes advantage of freeze avoidance as diapausing larvae for overwintering in the southern region, whereas it exhibits freeze tolerance in diapause in the northeastern region.     

海南岛尖峰岭山地雨林的群落结构、物种多样性以及在世界雨林中的地位

位于海南岛西南部的尖峰岭是目前我国为数不多、保存得较为完好的具有热带雨林性质的森林类型。在较典型的山地雨林中,设置1hm^2的固定样地,记录到DBH≥5．0cm的乔木171种,隶属于52科93属,总株数1099株,其中乔木种株数为1024。样地的Shannon—Wiener指数(H')、均匀度指数(E)和Simpson指数(D)分别为4．11、0．80和0．97,但取样面积和测定个体的起始大小等取样技术对物种多样性指数有显著的影响。随着取样面积的增加,H’值逐渐增加;但超过了4000m^2以后,增加不明显。E和D值在取样面积达到2000m^2后,基本保持不变：随着测定个体起始直径的增加,物种数、科数、H'和D都呈现出明显的减少趋势,而E值增加。径级频度分布的分析表明,该山地雨林的垂直结构可以划分成4个层次,每个层次的个体大小在空间上呈均匀或随机分布。从气候学、科属组成以及与世界热带雨林物种多样性的比较等方面,讨论了尖峰岭山地雨林在世界雨林中的地位。气候学分析表明,尖峰岭山地雨林在温度带上属于亚热带／暖温带范围,但由于其丰沛的降水量,使物种多样性较为丰富,具备了雨林的特点。对科属组成的分析表明,亚热带／暖温带科属占优势,其中典型的亚热带／暖温带科——壳斗科和樟科占总重要值的34％以上,而热带科属成份较少。与世界其他地区的典型热带林相比较,尖峰岭山地雨林的物种丰富度显著偏低,但高于某些降水量少的地区的热带林。因此,我们认为尖峰岭山地雨林与典型热带雨林有较大差别,具有由热带雨林向亚热带／暖温带雨林过渡的性质。此外,文本提出了平均种群密度(MPD)和种数一个体数关系这两种反映物种多样性测度的指标和表达式,并利用样地资料进行了分析。     

夏季南海北部纤毛虫群落组成及其水平分布

在2007年中国科学院南海海洋研究所南海北部开放航次期间,设计了两条纤毛虫采样断面(X断面、Y断面),共13个站位,涵盖了珠江冲淡水区、粤东上升流区和陆坡开阔海区,旨在对纤毛虫的种类组成和空间分布及其影响因素进行探讨。共检出4纲8目22属38种纤毛虫,其中种类数最多的属是砂壳目拟铃虫属(9种),其次是急游目急游属(5种)。本航次中纤毛虫主要是砂壳目纤毛虫(27种),共鉴定出砂壳虫15属27种。纤毛虫优势种为蚤状中缢虫Mesodinium pulex(18.1%),其次是丁丁急游虫Strombidium tintinnodes(9.7%),盾形拟铃虫Tintinnopsis urula(5.8%)。纤毛虫种类数和丰度从近岸向外海逐渐减少,纤毛虫种类数与温度(R2=0.53,P0.05)和盐度(R2=0.43,P0.05)呈负相关,随着温度的升高,纤毛虫种类数逐渐降低。纤毛虫丰度与温度和盐度相关性并不明显,这可能由于受上升流的影响,近岸上升流高盐区存在着纤毛虫丰度较为丰富的情况。叶绿素a浓度与纤毛虫种类数(R2=0.36,P0.05)和纤毛虫丰度(R2=0.36,P0.05)呈正相关,近岸浮游植物生物量高,纤毛虫种类丰富,丰度大,叶绿素a沿纵断面降低,纤毛虫种类数和丰度也降低。     

A new southern limit for the distribution ofAlouatta caraya in Rio Grande do Sul State,Brazil

The discovery of two groups of the black howler monkey,Alouatta caraya, inhabiting two orchards on a cattle farm, Fazenda Casa Branca (29°56′S, 55°59′W), Rio Grande do Sul State, Brazil, represents a new southern limit for the geographic distribution of this species.     

Estimation of heritability and genetic trend in populations at a physiological limit

Summary Limits on physiological processes, though perhaps unknown, must exist. The reported simulations evaluate the effect of a physiological limit on the estimation of genetic parameters and genetic progress. Simulation experiments reveal no change in the estimate of heritability, even for limits as restrictive as 1.5 phenotypic standard deviations above the population mean. However, estimates of additive genetic and environmental variance shrink as limits on performance increase in severity. Simulated physiological limits do not affect the rate of genetic progress. However, absolute measures of estimated genetic change are less than those predicted by response equations.     

夏、冬季南海北部浮游植物群落特征

对2009年7月19日—8月16日和2010年1月6—30日南海北部(18°—23.5°N、109°—120°E)两个航次的浮游植物样品应用Utermhl方法进行了分析鉴定。结果如下:夏季样品鉴定浮游植物4门72属150种,浮游植物细胞丰度范围为(0.16—6001.78)×103个/L,平均细胞丰度为26.49×103个/L,硅藻的平均细胞丰度为25.81×103个/L,主要优势种属有铁氏束毛藻(Trichodesmium thiebautii)、菱形海线藻(Thalassionema nitzschioides)、柔弱伪菱形藻(Pseudo-nitzschia delicatissima)及裸甲藻(Gymnodinium spp.)等;冬季样品鉴定浮游植物4门58属168种,浮游植物细胞丰度范围为(0.08—37.52)×103个/L,浮游植物平均细胞丰度为2.69×103个/L,硅藻的平均细胞丰度为2.49×103个/L,主要优势物种为菱形海线藻、伏氏海线藻(Thalassionema frauenfeldii)及短刺角毛藻(Chaetoceros messanensis)等;夏季调查区5m层浮游植物细胞丰度的平面分布由近岸到外海迅速减少,高值区主要在广东东部近岸及海南东部近岸;冬季则在珠江口近岸和海盆区出现较高值。两次调查中,浮游植物细胞丰度在浅水站位(200m)远高于深水站位(200m);较冬季相比,夏季浮游植物平均细胞丰度偏高,但物种丰富度却略偏低。夏、冬季浮游植物的香农-威纳多样性指数平均值分别为2.12和2.36,Pielou均匀度指数平均值分别为0.79和0.81。两个航次调查中,浮游植物细胞丰度均与盐度表现出显著性负相关性;在冬季还与磷酸盐浓度表现出显著性负相关性。     

Pyruvate kinase functions in hot and cold organs of tuna

Summary The skipjack tuna maintains its red skeletal musculature well above ambient temperatures while the temperature of the heart is within 1°C of that of the water. These two tissues exhibit tissue specific forms of pyruvate kinase. The red muscle has one form while the heart has two.TheK _m(PEP) of the red muscle enzymes rises with temperature, within the normal temperature range of the tissue. The affinity of the major form of the heart enzyme for phosphoenolpyruvate is relatively independent of temperature over the physiological temperature range.K _m(ADP) values are temperature independent for both enzymes.Inhibition by alanine of both enzymes is temperature dependent and rises with temperature. The same is true of ATP inhibition of the heart enzyme, but ATP inhibition of the red muscle enzyme is temperature independent. Fructose diphosphate reverses alanine and ATP inhibition at all temperatures.With both enzymes, temperature affects substrate affinities and the sensitivity of the enzyme to metabolite effectors. These effects can be rationalized in terms of physiological significance only in the case of the red muscle enzyme.List of abbreviations ADP adenosine diphosphate - ATP adenosine triphosphate - EDTA ethylene diamine tetra acetic acid - FDP fructose 1,6 diphosphate - LDH lactate dehydrogenase - NADH nicotinamide adenine dinucleotide (reduced) - NAD nicotinamide adenine dinucleotide (oxidized) - PEP phosphoenol pyruvate     

Physiological responses and thermal sensations of the elderly in cold and hot environments

1. 1. 10 elderly and 10 college-aged females served as subjects in cold and heat environments. The subjects changed into the standard clothing (0.63 clo), and stayed in the neutral environment (25°C) for 23 min, thereafter they were exposed to the cold (10°C) or hot (35°C) environment for 49 min.

2. 2. Then they returned to the neutral environment, and stayed there for 47 min. Oral temperature, skin temperatures at 10 sites, blood pressure and thermal sensation were measured during the experiments.

3. 3. In the cold environment, the elderly could not reduce heat loss by vasoconstriction as did young people, and their blood pressures increased more rapidly than in young people. In the hot environment, the elderly could not promote heat loss by vasodilation as did young people. Moreover, there is a delayed sensitivity to cold for the elderly. Therefore, in the houses of the elderly, it is important to have heating and cooling systems which also includes the areas where the people do not stay for a long period of time (e.g. toilet, passageways).