A TECHNIQUE FOR THE ANALYSIS OF EPISTATIC GENE ACTION II. THE APPLICATION OF THE METHOD

With a method based on probability of phenotypic ratios being produced by crosses involving two pairs of interacting genes, data from genetic studies of Impatiens Sultana Hook. f. (Balsaminaceae) were analysed. Nine genes postulated to control floral color are: P, purple; I and W, white; R, red; O, orange; F, fuchsia; D, red; E, red; S, salmon. Epistatic action was evaluated, but progeny counts were too small for linkage to be determined.     

A TECHNIQUE FOR THE ANALYSIS OF EPISTATIC GENE ACTION I. THE METHOD OF ANALYSIS

The thirty-two possible genic crosses involving two pairs of nonlinked genes were simulated. The anticipated progeny of each cross was analyzed according to each of the seven basic types of epistatic action. A key was devised to facilitate the recognition of genic action since most phenotypic progeny ratios are produced exclusively either by phenotypically similar parents or phenotypically dissimilar parents. Only ratios of 3:1, 2:1, and 1:1 can be produced by both types of parents.     

A COMPARISON OF THREE INDIRECT METHODS FOR ESTIMATING AVERAGE LEVELS OF GENE FLOW

Three methods for estimating the average level of gene flow in natural population are discussed and compared. The three methods are F_ST, rare alleles, and maximum likelihood. All three methods yield estimates of the combination of parameters (the number of migrants [Nm] in a demic model or the neighborhood size [4πDσ²] in a continuum model) that determines the relative importance of gene flow and genetic drift. We review the theory underlying these methods and derive new analytic results for the expectation of F_ST in stepping-stone and continuum models when small sets of samples are taken. We also compare the effectiveness of the different methods using a variety of simulated data. We found that the F_ST and rare-alleles methods yield comparable estimates under a wide variety of conditions when the population being sampled is demographically stable. They are roughly equally sensitive to selection and to variation in population structure, and they approach their equilibrium values at approximately the same rate. We found that two different maximum-likelihood methods tend to yield biased estimates when relatively small numbers of locations are sampled but more accurate estimates when larger numbers are sampled. Our conclusion is that, although F_ST and rare-alleles methods are expected to be equally effective in analyzing ideal data, practical problems in estimating the frequencies of rare alleles in electrophoretic studies suggest that F_ST is likely to be more useful under realistic conditions.     

用YADE法克隆球孢白僵菌类枯草杆菌蛋白酶基因CDEP-1的启动子及启动子序列分析

扩增与已知序列相连的未知序列是一项常用的分子生物学技术。与其它方法相比,目前在棉花上应用的YADE法具有效率高,成本低和假阳性低等特点。因此,作者尝试将该法引入到昆虫病原真菌的分子生物学研究,并取得了成功,建立了适合于球孢白僵菌和金龟子绿僵菌的YADE的技术体系。类枯草杆菌蛋白酶在昆虫病原真菌穿透寄主体壁时起重要作用,作者在已克隆的球孢白僵菌类蛋白酶基因CDEP-1的基础上,利用YADE法,克隆类球孢白僵菌类枯草杆菌蛋白酶基因CDEP-1的启动子CDEPP。序列分析发现:CDEPP中没有明显的TATA和CAAT框,含有8个可能的碳调控因子的结合位点5'>(g/c)YggRg<3'和2个氮调控因子的结合位点——相隔很近的GATA。这与CDEP-1的表达受碳/氮抑制的结果一致。本文的结果将会为研究CDEP-1的表达规律奠定基础。     

A METHOD FOR ESTIMATING MASS OF LARGE PINNIPEDS

Fifty-two male elephant seals were weighed and photographed at Año Nuevo State Reserve, California, to establish a predictive relationship between photographically measured morphological variables (length, side area, and girth area) and body mass. Regression of mass on these variables revealed that side area, roughly equivalent to a longitudinal cross-section, was the most useful single variable for predicting mass, and that adding the other two variables to side area slightly improved the accuracy of the photogrammetric technique. Curvilinear regressions based on a power model provided the best predictive relationships. This technique may prove useful for estimating body mass of other pinnipeds.     

ESTIMATION OF GENE FLOW FROM F-STATISTICS

We present theory clarifying the general behavior of F_ST-based and G_ST-based estimators of gene flow, and confirm these predictions with simulations. In particular, we use the correlation of genes within groups within populations to define an estimator. The theoretical value of the correlation doe not depend on the number of groups in a population, and properties of the estimated correlation do not depend on the number of groups sampled or the number of individuals sampled per group. This invariance is in contrast to properties of G_ST. For a complete census of a population, bias and variance considerations would suggest the use of the G_ST-based estimator of gene flow, but lack of knowledge of population size or group number in practice suggests preference be given to the correlation-based estimator. We acknowledge that these estimators require that several conditions of a population-genetic model be met, since they do not make use of direct observations on the flow of genes. Our results differ from some of those based on simulation in a series of recent papers by M. Slatkin.     

A METHOD FOR THE REMOVAL OF THE JELLY AND VITELLINE MEMBRANE FROM THE EMBRYOS OF XENOPUS LAEVIS

A simple procedure is described for removing the jelly and vitelline membrane of Xenopus laevis embryos. The method is based on the observation that incubation of the embryos in the mixed solution of trypsin and sodium thioglycolate at pH 8.0 causes effective dissolution of these structures. This solution is equally effective in this respect on the embryos at different developmental stages. Normal development is obtained from all of the denuded neurulae and from many of the denuded earlier embryos. Some chemical properties of the jelly and the vitelline membrane of Xenopus laevis are discussed based upon these observations.     

A MULTISPECIES APPROACH TO THE ANALYSIS OF GENE FLOW IN MARINE SHORE FISHES

Ten species of marine shore fishes with a wide range of life-history strategies were collected from four areas in southern California, U.S.A., and Baja California, Mexico, and examined for patterns of genetic differentiation. Multilocus D and F_ST values (based on 32–42 presumptive gene loci in each species) were both negatively correlated with estimated dispersal capability. These results were robust to variations in the number and type of loci used in the analysis and are compatible with the hypothesis that levels of genetic differentiation in these shore fishes are determined primarily by gene flow and genetic drift. There is no a priori reason to expect the observed correlation to result from natural selection or historical factors. The findings thus suggest that populations of these shore fishes are in at least a quasi-equilibrium with respect to migration, mutation, and genetic drift. Present data were also used to compare estimates of mN_e obtained by three different methods. Estimates based on F_ST values calculated by the methods of Nei and Chesser (F_ST(N)) and Weir and Cockerham (F_ST(W)) were highly correlated, but F_ST(N) ≤ F_ST(W) for every species, leading to generally higher mN_e estimates for Nei and Chesser's method. Estimates of mN_e based on the frequency of private alleles (Slatkin, 1985a) were not as strongly correlated with dispersal capability as were F_ST and D values. A low incidence of private alleles in many species may be responsible for this relatively weak correlation and may limit the general usefulness of Slatkin's method. In spite of their sensitivity to natural selection, F_ST and D may be better indicators of relative gene flow levels for high gene flow species.     

苹果液泡酸性转化酶基因片段的克隆及序列分析

在分析植物可溶性转化酶基因的保守区序列基础上,设计了一对PCR引物,以苹果(辽伏)基因组DNA为模板,采用PCR方法扩增出长约743bp的DNA片段,克隆入pUCm—T载体,测序结果表明,所获得的片段推测为苹果酸性转化酶基因的片段,该基因片段长度为743bp,是开放阅读框的一部分,无内含子。其序列已在GenBank中登记(登记号为AF433644)。在Gen-Bank中进行同源性检索,结果表明该成员编码的氨基酸与植物可溶性酸性转化酶的氨基酸同源性较高,与温州蜜柑(GenBank AF014925)、胡萝卜(X67163)、甜菜(GenBank X81796)和绿豆(GenBank D10265)液泡酸性转化酶基因编码蛋白质的氨基酸分别具有80％、80％、78％和77％的同源性。而与定位于细胞壁的酸性转化酶(不溶性)同源性较低,由此可推测出研究获得的苹果转化酶基因可能定于液泡。该基因片段的获得对于深入研究苹果蔗糖代谢以及果实发育和品质形成具有重要的意义。     

DEVELOPMENT OF THE CUTICULAR LAYERS IN ANGIOSPERM LEAVES

Schieferstein , R. H., and W. E. Loomis . (Iowa State U., Ames.) Development of the cuticular layer in angiosperm leaves. Amer. Jour. Bot. 46(9): 625–635. Illus. 1959.—The cuticularized layers of leaves and other plant surfaces consist of a primary cuticle, formed by the oxidation of oils on exposed cell walls, plus various surface and subsurface wax deposits. The primary cuticle appears to form rapidly on the walls of any living cell which is exposed to air. Surface wax is present on the mature leaves of about half of the 50 or 60 species studied. In general, wax is extruded at random through the newly formed cuticle of young leaves and accumulated in various reticulate to semicrystalline patterns. No wax pores through the cuticle or primary wall can be observed in electron-micrographs of dewaxed mature leaves. Wax accumulations on older leaves are generally subcuticular and may involve the entire epidermal wall. These deposits appear to be of considerably greater ecological significance than those on the surface. Isolated cuticular membranes from Hedera helix increased slightly in permeability to water with age of the leaf, but permeability to 2,4-D decreased 50 times. Evidence based on the patterns of cellulose in primary walls, of surface wax on growing leaves, of the appearance of the cuticle at the margins of growing epidermal cells, of the forms of the cuticle plates digested from growing and older leaves, and of the marginal location of new wax deposits on growing maize leaves is presented to support the thesis that the enlargement of the outer surface of the epidermal cells of leaves occurs at the margins of the surface. Earlier formed cuticle and wax are thus undisturbed during growth. These observations, coupled with evidence for apical growth in fibers, root hairs, etc. suggest that the primary walls of angiosperm cells are formed in specific, localized growth regions, rather than by plastic extension and apposition.     

THE DEVELOPMENT OF A COMPARATIVE METHOD FOR THE EVALUATION OF THE MOTH-PROOFNESS OF WOOL SERGE

Existing test methods for the moth-proofness of wool were compared in inter-laboratory experiments and found to be lacking in accuracy and agreement between laboratories.
Several factors influencing the usefulness of such a test method were investigated, and it was found that a considerable gain in accuracy could be reached if weight loss due to larval attack on test samples was referred to weight loss obtained with a standard wool serge impregnated with a standard moth-proofing substance. Apart from this principle, improvements in the general testing procedure, including the number of test samples and test animals used, the definition of weight loss and the introduction of strict randomization procedures proved to be valuable.
As a provisional reference standard, wool serge impregnated with dinitro-α-naphthol was adopted. A tolerance level for the moth-proofness of wool serge was laid down.     

A SENSITIVE ENZYMATIC-ISOTOPIC METHOD FOR THE ANALYSIS OF TYRAMINE IN BRAIN AND OTHER TISSUES

Abstract— An enzymatic-isotopic assay for the measurement of tyramine with a sensitivity of 1.0 ng has been developed. Using this assay, the endogenous content of tyramine in various tissues from adult rats has been determined. The highest tyramine content was found in rat heart atria, followed by salivary gland, kidney, and brain. Within the brain the distribution of tyramine is heterogeneous and the highest tyramine content was localized in the striatum.     

SPERM-MEDIATED GENE FLOW AND THE GENETIC STRUCTURE OF A POPULATION OF THE COLONIAL ASCIDIAN BOTRYLLUS SCHLOSSERI

The genetic structure of populations of sessile and sedentary organisms is often characterized by microgeographic differentiation in gene frequencies and deviations from panmixia. In many terrestrial botanical systems, restricted gene flow via seed and pollen dispersal may have an important role in promoting such genetic patterns. Until recently, however, limited dispersal of the sexual propagules of benthic invertebrates has not been considered to play a comparable role in aquatic systems. Based on paternity analyses in the field using rare allozyme markers, it appears that concentrations of sibling sperm of the sessile, colonial ascidian Botryllus schlosseri decline rapidly within 50 cm of a source colony. In combination with spatially restricted dispersal of brooded larvae, limited dispersal of sperm should enhance the potential for genetic diversification and inbreeding. However, analysis of allelic and genotypic frequencies at three independent, polymorphic allozyme loci using F-statistics provides little evidence for microgeographic variation in gene frequencies. This lack of differentiation can be explained in terms of the absolute number (rather than concentration) of gametes and larvae dispersing from a point source, which—depending on diffusion and geometric assumptions—may actually increase with distance. In contrast to the absence of differentiation, levels of inbreeding are high, even within the confines of 25 times 25–cm quadrats. The absence of genetic diversification and presence of inbreeding caution against inferring levels and causes of gene flow from indirect analysis of genetic structure and, conversely, making predictions about genetic and breeding structure based solely on direct analysis of gene flow.     

百色地区壮族学生体质发育调查分析

本文调查了4800名广西百色地区壮族7－18岁学生的身高、坐高、体重、胸围、肩宽和骨盆宽6项指标,用医学统计程序集（POMS）进行统计运算,并把所得体质数据进行了城乡比例,不同年份比较,壮族与汉族比较,壮族与蒙古族和其他少数民族比较,壮族与日本学生 的数据进行了比较。