山东沿海菲律宾蛤仔不同地理群体遗传多样性的AFLP分析

利用AFLP技术对山东沿海菲律宾蛤仔（Ruditapes philippinarum）4个野生群体（乳山、无棣、牟平、即墨）进行了遗传多样性分析。采用6对引物组合对4个群体进行扩增,共得到356个位点,乳山群体、无棣群体、牟平群体和即墨群体的多态位点比例依次为74.40%、70.50%、72.80%、74.70%,具有较高的遗传多样性水平。其中,即墨群体多态性比例最高,无棣群体多态性比例最低。聚类分析表明,各群体间的遗传距离在0.0263～0.0448之间,乳山群体和无棣群体间的遗传距离最近(0.0263),两群体首先聚在一起,随后与牟平群体和即墨群体聚在一起。     

UV and optical spectral properties in early-type galaxies

We investigate UV and optical spectra of a sample of nearby early-type galaxies with evidence of nuclear line emission. The spectral signatures of various contributors to the UV, such as the interstellar medium and various stellar populations are analyzed and compared with the optical spectral properties. We discuss the impact of these effects on the observational properties of galaxy evolution. This revised version was published online in August 2006 with corrections to the Cover Date.     

Larval life span,larval settlement,and early growth of Evechinus chloroticus (Valenciennes)

Development, settlement, and subsequent metamorphosis on several substrata were observed in cultures of Evechinus chloroticus larvae. The period from fertilisation to metamorphosis ranged between 30 and 63 days for larvae collected from spawnings induced at 3 different times. Newly settled sea urchins collected from the field grew about 1 mm per month in aquaria. Correlation of the larval life span with the growth rate of newly settled sea urchins suggested that the earliest spawning could occur was mid‐November. This finding corroborates the results of previous histo‐logical studies of the gonads of adult sea urchins in the Hauraki Gulf, New Zealand.     

斑节对虾4个地理群体遗传多样性的AFLP分析

为研究斑节对虾(Penaeus monodon)4个地理群体的遗传背景,作者应用AFLP分子标记技术对非洲(F)、中国三亚(S)、泰国(T)和印度尼西亚(Y)的斑节对虾群体进行遗传多样性分析。选取8对引物组合对斑节对虾4个群体共128个个体进行分析比较,共获得1 000个位点,其中多态性位点数为830个,各群体多态位点比率为47.8%~58.5%;群体Nei’s遗传多样性指数为0.0917~0.1271,Shannon’s信息指数为0.1484~0.2032。4个群体间的遗传距离,Y与F之间最大,为0.331,T与S之间最小,为0.217。4个群体UPGMA聚类时,S、T与Y聚为一支,F为单独一支;128个个体的UPGMA聚类结果表明,F群体除4个个体外其余个体聚为一大支,S、T、Y群体的部分个体互相混杂。AMOVA分析发现,35.92%的变异来自于群体间,64.08%的变异来自于群体内,群体间的遗传分化系数为0.3592,表明4个群体间的遗传分化程度很大。本研究为斑节对虾遗传育种提供了种质遗传背景资料,并为斑节对虾资源的开发与利用提供基础数据。     

Population statistics study of radio and gamma-ray pulsars in the Galactic plane

We present results of our pulsar population synthesis of normal and millisecond pulsars in the Galactic plane. Over the past several years, a program has been developed to simulate pulsar birth, evolution and emission using Monte Carlo techniques. We have added to the program the capability to simulate millisecond pulsars, which are old, recycled pulsars with extremely short periods. We model the spatial distribution of the simulated pulsars by assuming that they start with a random kick velocity and then evolve through the Galactic potential. We use a polar cap/slot gap model for γ-ray emission from both millisecond and normal pulsars. From our studies of radio pulsars that have clearly identifiable core and cone components, in which we fit the polarization sweep as well as the pulse profiles in order to constrain the viewing geometry, we develop a model describing the ratio of radio core-to-cone peak fluxes. In this model, short period pulsars are more cone-dominated than in our previous studies. We present the preliminary results of our recent study and the implications for observing these pulsars with GLAST and AGILE.      

The resolved red giant branches of E/S0 galaxies

Formation paradigms for massive galaxies have long centered around two antipodal hypotheses – the monolithic-collapse and the accretion/merger scenarios. Empirical data on the stellar contents of galaxy halos is crucial in order to develop galaxy formation and assembly scenarios which have their root in observations, rather than in numerical simulations. The Hubble Space Telescope (HST) has enabled us to study directly individual stars in the nearby E/S0 galaxies Cen A, NGC 3115, NGC 5102, and NGC 404. We here present and discuss HST single-star photometry in V and I bands. Using color-magnitude diagrams and stellar luminosity functions, we gauge the galaxies' stellar contents. This can be done at more than one position in the halo, but data with deeper limiting magnitudes are desired to quantify the variation of metallicity with galactocentric radius. We here compare the color distributions of red giant stars with stellar isochrones, and we intercompare the galaxies' halo populations, noting that their total absolute V magnitudes cover the range from about –21.5 to –17.5. In the future, we plan to model the stellar metallicity distributions with the aim to constrain chemical enrichment scenarios, a step towards unravelling the evolutionary history of elliptical and lenticular galaxies. This revised version was published online in August 2006 with corrections to the Cover Date.