夏季绿洲生态环境对荒漠背景地表能量过程的扰动

利用观测试验资料,对比分析了夏季典型晴天敦煌绿洲与周围荒漠戈壁背景地表过程的差异,揭示了绿洲生态系统对干旱区荒漠背景地表过程的扰动特征。结果表明:绿洲地表净辐射日平均要高出周围荒漠戈壁背景60 W/m2以上,约占绿洲净辐射的1/4以上。对绿洲高出的净辐射贡献最大的是绿洲相对低的地表长波辐射,其次是较高的太阳总辐射。而绿洲相对较低的大气长波辐射对高出的净辐射有较大的负贡献,特别是地表反射辐射也有很小的负贡献。绿洲高出的地表净辐射主要贡献于加强潜热和地热流量,还有一部分被绿洲地表能量不平衡差额所占,它实际上可能由一般地表热量平衡所不考虑的垂直热量平流来输送。而绿洲明显低于荒漠背景的感热通量则节省了一部分净辐射能量。     

不同时间草地火烧后群落地上生物量结构的变化

不同时间草地火烧后,群落地上生物量结构发生不同程度的变化,最明显的是火烧地各层没有立枯体组分,未烧地立枯体随季节推迟逐渐转向下层．火烧地茎矮化,各层段叶生物量皆高于未烧地,未烧地各层段茎叶比例高于火烧地．火烧地的光线通透系数高于未烧地．     

Evolutionary and morphological significance of the deflecting wrinkle in the lower molars of the Hominoidea

The deflecting wrinkle is a well-known character state of the lower m2 and M1 of the human dentition, but there is little information regarding its presence in great apes. The deflecting wrinkle is more frequent on M2-3 in all extant pongid genera studied in this paper except Pan paniscus, in which M1 has the highest frequency (16.0%) and in which this wrinkle is absent on M3. In Gorilla, it is absent on M1, with only a low incidence on M2-3. Its greatest frequency in Pongo is always on M2 (20.2%), which is the greatest expression of the trait in the great apes. We interpret the presence of the deflecting wrinkle as an incidental effect and suggest that it represents a plesiomorphic character state in the Hominoidea.     

Selection on body size and sexual size dimorphism differs between host species in a seed-feeding beetle

Sexual size dimorphism varies substantially among populations and species but we have little understanding of the sources of selection generating this variation. We used path analysis to study how oviposition host affects selection on body size in a seed-feeding beetle (Stator limbatus) in which males contribute large ejaculates (nuptial gifts) to females. Females use nutrients in these ejaculates for egg production. Male body size, which affects ejaculate size, affects female fecundity and is thus under fecundity selection similar in magnitude to the fecundity selection on female body size. We show that when eggs are laid on a host on which larval mortality is low (seeds of Acacia greggii) fecundity predicts fitness very well and fecundity selection is the major source of selection on both male and female adult size. In contrast, when eggs are laid on a host on which larval mortality is high (seeds of Parkinsonia florida) fecundity poorly predicts fitness such that fecundity selection is relaxed on both male and female size. However, because egg size affects larval mortality on this poor host (P. florida) there is selection on female size via the female size --> egg size --> fitness path; this selection via egg size offsets the reduction in fecundity selection on female, but not male, body size. Thus, differences in host suitability (due to differences in larval mortality) affect the relative importance of two sources of selection on adult body size; fecundity selection on both male and female body size is lower on the poor quality host (P. florida) relative to the high quality host (A. greggii) whereas selection on female body size via effects of egg size on offspring survival (body size --> egg size --> fitness) is greater on the poor quality host relative to the high quality host. Because selection via the egg size path affects only females the difference in larval survival between hosts shifts the relative magnitude of selection on female vs. male size. Researchers working on other study systems should be alerted to the possible importance of subtle, but consequential, indirect selection on their study organisms.     

江苏省海滩植被演替的研究

江苏省海滩植被可分为滨海盐土植被、盐沼植被及海滩沙生植被三个基本类型。本文论述了这些植被类型的演替规律。滨海盐土植被与盐沼植被的演替,外因于土壤盐分含量递减与有机质含量的递增;海滩沙生植被的演替,外因于土壤沙颗粒大小及其相应的土壤含水量的变化,所以海滩植被演替为外因动态演替。     

国人颅骨颈动脉管外口及其周围某些结构的形态观察与测量

本文对国人颅骨133例,266个颈动脉管外口形状大小进行了观察与测量。结果表明:颈动脉管外口形状不一。可区分为圆形、卵圆形和南瓜子仁形三种,其中以圆形者为数最多。颈动脉管外口长宽径和距颈静脉窝及锥体尖端之间距离两侧不等,并具有地区性差异。鼓小管下口在个别颅骨缺如。颈静脉窝之大小深浅不一,其中以右侧较大而深者为最多。     

安徽与邻近省藓类植物区系数量统计比较

区系中的物种丰富度是衡量该区域中植物群落的环境条件、群落结构以及群落发育程度等的重要指标,利用丰富度指数公式,通过对安徽省与其相邻的六个省的藓类植物进行比较,可以看出安徽省藓类植物的物种多样性位居第三,是较为丰富的地区之一;在七省中安徽藓类植物属的系数最低,说明安徽藓类植物区系的丰富度和生境条件的复杂程度是较高的;比较七省的藓类植物丰富度指数与自然地理条件的关系,可认为纬度、降水量、温度以及丘陵山地占该地区总面积的百分比等地理条件综合作用影响藓类植物分布的丰富程度。     

Characterization of a plasma membrane protein present in non-myelin-forming PNS and CNS glia,a subpopulation of PNS neurons,perineurial cells and smooth muscle in adult rats

Summary A plasma membrane protein common to nonmyelin-forming peripheral glia, including non-myelin-forming Schwann cells, satellite cells and enteric glia, is recognized and defined by monoclonal antibody A5E3. It is not detectable immunohistochemically on myelin-forming Schwann cells. The antigen is also present in large amounts on smooth muscle cells and perineurial cells, on some PNS neurons, and at lower levels on astrocytes of adult rat. In neonatal but not adult animals, the antigen is present on skeletal muscle fibres and myoblasts. In immunoblots and immune precipitation experiments on smooth muscle and Schwann cell extracts the antigen is a polypeptide with an apparent molecular weight of 130 kd. In being present in some non-neural tissues, albeit very highly restricted in cell type, this antigen resembles several other cell surface glycoproteins found in large amounts in the nervous system.     

Interval observers for biochemical processes with uncertain kinetics and inputs

This paper concentrates on the state observation in bioprocesses when there is uncertainty on the process parameters and/or the process inputs. An interval observer is designed on the basis of the cooperativity properties of the model for a standard stirred tank bioreactor model with a single microbial growth and a kinetic model depending on the substrate concentration. Further assumptions are the (lower and upper) boundedness of the specific growth rate and the inlet substrate concentration. Mathematical analysis of the stability and convergence of the interval observer is performed both in absence and in presence of uncertainty on the measurements. It is shown in particular that when the process inputs are known, the static observation error on the unknown state is inversely proportional to one of the observer gains. The performance of the interval observer are also illustrated through numerical simulation.     

Transport via the transcytotic pathway makes prostasin available as a substrate for matriptase

The matriptase-prostasin proteolytic cascade is essential for epidermal tight junction formation and terminal epidermal differentiation. This proteolytic pathway may also be operative in a variety of other epithelia, as both matriptase and prostasin are involved in tight junction formation in epithelial monolayers. However, in polarized epithelial cells matriptase is mainly located on the basolateral plasma membrane whereas prostasin is mainly located on the apical plasma membrane. To determine how matriptase and prostasin interact, we mapped the subcellular itinerary of matriptase and prostasin in polarized colonic epithelial cells. We show that zymogen matriptase is activated on the basolateral plasma membrane where it is able to cleave relevant substrates. After activation, matriptase forms a complex with the cognate matriptase inhibitor, hepatocyte growth factor activator inhibitor (HAI)-1 and is efficiently endocytosed. The majority of prostasin is located on the apical plasma membrane albeit a minor fraction of prostasin is present on the basolateral plasma membrane. Basolateral prostasin is endocytosed and transcytosed to the apical plasma membrane where a long retention time causes an accumulation of prostasin. Furthermore, we show that prostasin on the basolateral membrane is activated before it is transcytosed. This study shows that matriptase and prostasin co-localize for a brief period of time at the basolateral plasma membrane after which prostasin is transported to the apical membrane as an active protease. This study suggests a possible explanation for how matriptase or other basolateral serine proteases activate prostasin on its way to its apical destination.     

海南竹类的地理分布及区系特征

通过对海南岛竹类区系地理成分进行统计、分析和对其分布、与邻近地区竹类区系关系的探讨,其区系特征归纳如下:1.拥有丰富的特有成分。2.区系的热带性质明显。3.分布上差异显著。4.区系原始、古老。5.与毗邻的广东竹类区系联系较多。     

Stresses on the limbs of quadrupedal primates

Data is presented from eight primates on the ground reaction forces on the limbs during locomotion. These subjects supported from 30 to 45% of their body weight on their forelimbs. Other quadrupedal mammals support 55-60% of their body weight on their forelimbs. The increase of peak vertical force with speed varies greatly between the subjects. The variation in weight supported by the forelimbs and the peak forces on the forelimbs is proposed to correlate with variation in locomotor adaptations. It is suggested that the occurrence of bipedalism in primates represents the extreme expression of the tendency in primates to reduce the compressive forces on their forelimbs.     

A probabilistic method for calculating the energy of hydrophobic interactions

A theoretical approach is developed for estimating the hydrophobic interaction energy on the molecular level. The underlying idea of the model is the fundamental relationship between the probability of the appearance of a solvent-excluded volume in fluid water as a result of density fluctuations, on one hand, and the free energy of primitive hydrophobic solutes, on the other. This probability is estimated basing on an information theory model in combination with experimental data on the distribution density and radial distribution function. The free energy of hydrophobic interactions is determined for a complex that consists of several hard spheres. The critical number of particles in the complex is estimated.     

Demography of source—sink populations and the evolution of ecological niches

Summary The demography of populations living in variable environments is an important factor molding the evolution of ecological niches, for it determines the relative strength of selection pressures on adaptations to different habitats. Here I consider a coarse-grained environment consisting of two habitat types and investigate how the selection pressure on reproductive success in different habitats depends on their quality and frequency and the dispersal pattern. The results suggest that selection on adaptations to optimal habitats will usually be stronger than on adaptations to poor habitats and the ecological niche will thus tend to be an evolutionarily conservative character. It is because under the habitat choice or limited dispersal that seem to prevail in natural populations, more individuals encounter the better habitat than would be expected solely on the basis of its relative area. This bias results in reduced selection pressure on reproductive success in the poorer habitat. With habitat choice or limited dispersal, selection pressure on reproductive success in the poorer habitat may exceed that on reproductive success in the better habitat only if the poorer habitat is much more frequent in the environment than the better habitat and the difference in their quality is not large.     

Persistent directional selection on body size and a resolution to the paradox of stasis

Directional selection on size is common but often fails to result in microevolution in the wild. Similarly, macroevolutionary rates in size are low relative to the observed strength of selection in nature. We show that many estimates of selection on size have been measured on juveniles, not adults. Further, parents influence juvenile size by adjusting investment per offspring. In light of these observations, we help resolve this paradox by suggesting that the observed upward selection on size is balanced by selection against investment per offspring, resulting in little or no net selection gradient on size. We find that trade‐offs between fecundity and juvenile size are common, consistent with the notion of selection against investment per offspring. We also find that median directional selection on size is positive for juveniles but no net directional selection exists for adult size. This is expected because parent–offspring conflict exists over size, and juvenile size is more strongly affected by investment per offspring than adult size. These findings provide qualitative support for the hypothesis that upward selection on size is balanced by selection against investment per offspring, where parent–offspring conflict over size is embodied in the opposing signs of the two selection gradients.     

广西侗族手指指毛的分布

本文调查了广西三江侗族18至50岁农民和学生279人(男153、女126)的手指指毛分布。结果说明,近侧和中间指节除发现一例女性没有指毛以外,其余均有指毛,远侧指节无指毛。男女两性间指毛的出现率无明显差异,左右手指指毛分布基本上对称。     

The effect of repeated cycles of selection on genetic variance,heritability, and response

Summary The genetic variance of a quantitative trait decreases under directional selection due to generation of linkage disequilibrium. After a few cycles of selection on individual phenotype, a limit is reached where there is no further reduction in the genetic variance. Bulmer's model is extended to an animal breeding situation where selection is on information on relatives rather than on the individual's own performance. Algebraic expressions are derived to predict the decrease in genetic variance and associated reductions in heritability and response in the limit. Consequences of the results are discussed in the context of breeding strategies.