Environmental control of phytoplankton productivity in turbulent turbid systems

Factors affecting phytoplankton productivity are analysed in turbid systems, such as shallow lakes and rivers. When resuspension from the sediment or loading from the catchment significantly increases inorganic (non-algal) turbidity and hence light attenuation potentials for high production are not realised. Energy available for phytoplankton growth is strongly regulated by underwater light availability which depends on the critical mixing depth, fluctuating light intensities and algal circulation patterns. Higher production rates in shallow waters are often compensated by greater algal respiration due to higher water temperatures when compared to deeper lakes.Total daily integral production of turbulent, turbid environments can be predicted from a combination of easily measured variables such as maximum photosynthetic rates, algal biomass, surface irradiance and some measure of underwater light attenuation.     

Divergence pattern and selective mode in protein evolution: The example of vertebrate myoglobins and hemoglobin chains

Summary The evolutionary relation of vertebrate myoglobin and the hemoglobin chains including the agnathan hemoglobin chain is investigated on the basis of a new view of amino acid changes that is developed by canonical discriminant analysis of amino acid residues at individual sites. In contrast to the clear discrimination of amino acid residues between myoglobin, hemoglobin a chain, and hemoglobin chain in warm-blood vertebrates, the three types of globins in the lower class of vertebrates show so much variation that they are not well discriminated. This is seen particularly at the sites that are ascertained in mammals to carry the amino acid residues participating in stabilizing the monomeric structure in myoglobin and the residues forming the subunit contacts in hemoglobin. At these sites, agnathan hemoglobin chains are evaluated to be intermediate between the myoglobin and hemoglobin chains of gnathostomes. The variation in the phylogenetically lower class of globins is also seen in the internal region; there the amino acid residues of myoglobin and hemoglobin chains in the phylogenetically higher class exhibit an example of parallel evolution at the molecular level. New quantities, the distance of sequence property between discriminated groups and the variation within each group, are derived from the values of discriminant functions along the peptide chain, and this set of quantities simply describes an overall feature of globins such that the distinction between the three types of globins has been clearer as the vertebrates have evolved to become jawed, landed, and warm-blooded. This result strongly suggests that the functional constraint on the amino acid sequence of a protein is changed by living conditions and that severe conditions constitute a driving force that creates a distinctive protein from a less-constrained protein.Offprint requests to: J. Otsuka     

Substance P-Evoked Calcium Mobilization and Ionic Current Activation in the Human Astrocytoma Cell Line U 373 MG: Pharmacological Characterization

Abstract— In the human astrocytoma cell line U 373 MG, application of substance P (SP) leads to a transient increase in cytosolic calcium concentration and to a biphasic current response in voltage-clamped cells. Using these two functional assays we have characterized pharmacologically the SP response in U 373 MG cells. SP and [l -Pro⁹]SP displayed high potencies in both assays with EC₅₀values of 2.5 ± 10^?9M and 1 ± 10^?9M on calcium responses and 110^?9M and 510^?9M on ion current responses, respectively. The high potency of SP and [l -Pro⁹]SP as well as the low potency of [Lys⁵,MeLeu⁹,N-Leu¹⁰]neurokinin A_(4-10) and the inactivity of senktide demonstrate the NK₁-type pharmacology of these responses. Furthermore, the NK₁ antagonists (±)-CP 96,345, its chloro analogue, (±)-cis-3-(2-chlorobenzylamino)-2-benz-hydrylquinuclidine, and RP 67580 were potent antagonists of both SP responses. For the calcium mobilization induced by SP (1 (10^?7M), the IC₅₀ values for the three antagonists were 4 ± 10^?10M, 4 ± 10^?9M, and 9 ± 10^?9M, respectively, whereas on the current response evoked by SP 10^?8M), the IC₅₀ values were 8 ± 10^?9M, 2.4 ± 10^?8M, and 1.2 10^?7M, respectively. Despite differences in the absolute IC₅₀ values obtained with both techniques, the relative potencies of the three antagonists correlate fairly well. The U 373 MG cell line provides a useful model system for studies of the pharmacology of the human NK₁receptor and its transduction mechanisms at the level of second messengers and modulation of ion currents.     

Morphological differentiation in Carduelis finches: Adaptive vs. constraint models

In this study we show that morphological diversification in the avian genus Carduelis (Carduelinae) has to a large extent been conservative. Using multivariate methods, we found only minor deviations from the common (ancestral) body-plan. In particular, variation in bill morphology was found to be more conservative than variation in other parts of the body. We argue that constraint models of population differentiation can successfully account for the variation in bill morphology in this genus, but are less successful in accounting for variation in other traits. This can be interpreted as a result of long-term overall stabilizing selection for a certain bill morphology which is related to the way the birds open seeds. A trait combination that is adaptive on the evolutionary time scale may thus act as a constraint on changes in bill morphology on the microevolutionary scale. We conclude that the most parsimonious explanation for low divergence in bill morphology in this genus is that all species have retained the ancestral bill morphology. This may mean that each species chooses its environment rather than being moulded by it. This argument seems to apply to bill morphology, but other traits studied in this genus appear to have evolved in a less constrained fashion. A new index of morphometric integration is introduced to describe covariance structures.     

烟草耐盐愈伤组织变异体对盐渍的适应性

用组织培养及逐步增加,NaCl浓度的方法,筛选出烟草耐盐愈伤组织变异体。能耐盐(2％ NaCl)的愈伤组织在2％ NaCl中继代29次,再移入无盐培养基中培养11和20代后不能保持提高的耐盐性,分别退化到只耐1.5％与1.0％ NaCl的水平。耐2％ NaCl愈伤组织产生的再生植株自交后代,其萌发种子、幼苗及成长植株均未能表现出耐盐性,说明用选择胁迫方法所筛选出的耐盐细胞系,其耐盐性的提高属于生理适应性。     

SELECTIVE PREDATION FOR VERTEBRAL PHENOTYPE IN GASTEROSTEUS ACULEATUS: REVERSAL IN THE DIRECTION OF SELECTION AT DIFFERENT LARVAL SIZES

Variation in the number of vertebrae is widespread in fishes, and is partly genetic in origin. The adaptive significance of this variation was tested by exposing larvae of the threespine stickleback (Gasterosteus aculeatus) to predation by sunfish (Lepomis gibbosus). Two vertebral characters were considered: the total number (VN) and the ratio of abdominal to caudal vertebrae (VR). Predation was selective for both characters, but selection was more directly related to VR than to VN. The direction of selection depended on larval length: as length increased, optimal VR decreased. Total selection for VR was a combination of direct selection and an indirect effect of selection acting on a correlated trait, the ratio of precaudal to caudal length. Direct and indirect selection were in opposing directions at a given larval length. Variation in vertebral number may be maintained in populations partly because the strength of selection is reduced by opposing directions between direct and indirect selection, and between total selection at different larval lengths.     

固定化细胞分布对动力学影响的模型化研究

通过对固定化Gluconobacter oxydans和Bacillus cereus的活细胞系统的研究,提出了固定化细胞不均匀分布模型,将此类分布与均匀分布(最劣分布模型)进行比较,分析了它们对固定化细胞内部的基质浓度分布、有效速率因子和选择率的影响,指出不均匀分布和均匀分布对于该固定化活细胞系统的动力学行为无显著影响,这一模型分析结果在实验中得以验证。通过无因次化分析,建立了适用于固定化生物催化剂动力学研究的模型方法。     

平菇丰收一号高产特性的研究

通过野生种分离选用的平菇丰收一号,染色体数为９（ｎ＝９）,菌丝生长速度比一般品种快２—３４ｃｍ／ｈ,平均投料０．５ｋｇ（块）产鲜菇０．６～２．５ｋｇ,个别单株重１０～２０ｋｇ左右,生物效率１００～１５０％,高者达２００％以上,是一种高产优质、适应性强的新菌种。     

Causes of covariation of phenotypic traits among populations

Morphological and life-history traits often vary among populations of a species. Traits generally do not vary independently, but show patterns of covariation that can arise from genetic and environmental influences on phenotype. Covariance of traits may arise at an among-population level when genetically influenced traits diverge among populations in a correlated manner. Genetic correlations caused by pleiotropy and/or gene linkage can cause traits to evolve together, but among-population covariance can also arise among traits that are not genetically correlated. For example, “selective covariance” can arise when natural selection directly causes correlated change in a suite of traits. Similarly, mutation, migration, and drift may also sometimes cause correlated genetic changes among populations. Because covariation of traits among populations can arise by several different processes, the evolution of suites of traits must be interpreted with great caution. We discuss the sources of among-population covariance and illustrate one approach to identifying the sources' using data on floral traits of Dalechampia scandens (Euphorbiaceae).