四川自贡大山铺蜀龙动物群——简报Ⅲ.蜥脚类

本文记述了中侏罗世蜥脚类一新属种——巴山酋龙(Datousaurus bashanensts gen. et sp. nov.)对李氏蜀龙(Shunosaurus lii)的特征进行了补充,讨论了它们在蜥脚类进化过程中的位置。     

中国下泥盆统脊椎动物化石组合层序

本文综合了滇、黔、川、桂等地的一些早泥盆世地层剖面中的脊椎动物化石的出露情况,粗略地描绘出了早期脊椎动物演化的一般特征,归纳成三个发展阶段。并以此为依据,讨论了下泥盆统的分层与对比。     

中国疫霉属异宗配合种的交配型

在疫霉属真菌中,很多种是重要的经济植物的病原菌,寄主范围广泛,包括乔木、灌木和各种农作物;为害性大,常带来严重的经济损失。本文主要研究疫霉异宗配合种的交配型。根据疫霉在纯培养和成对培养(dual culture)中产生有性器官的能力,疫霉属可分为同宗配合种和异宗配合种两大类群。异宗配合种的A~1交配型与同一种或其它种的A~2交配型进行成对培养时,可以形成有性器官。两个可亲合菌系配合而形成有性器官时,可能发生基因重组,其结果将使病原菌具有更强的生存能力、致病力以及更广泛的寄主范围。因此,研究疫霉两种不同的交配型的分布,不仅对认识病害的发生发展规律,进一步设计防治措施有着重要意义,而且对疫霉属的起源、演化和移栖也有着深远的理论意义。作者对收集到的7个异宗配合种:Phytophthora capsici,P.cinnamomi,P.citrophthora,P.colocasiae,P.infestans,P.nicotianae,P.palmivora的38个分离物进行了交配型的研究,测定工作使用澄清的Campbell蔬菜汁琼脂培养基(V8C),用于确定交配型的菌系有P.nicotianae var.parasitica A~1,P.nicotianae var.parasitica A~2,P.cinnamomi A~1,P.cinnamomi A~2,P.palmivora A~1,P.palmivora A~2.每个分离物分别与已知种的A~1和A~2两个菌系成对接种于同一V8C平板上,放入25℃温箱中培养,2周后在两个菌落的连线上检查有性器官的产生情况。实验结果表明,中国疫霉属异宗配合种的这些分离物的交配型与寄主或地理分布似无相关性,同一种植物上分离到的同种疫霉可以是A~1交配型,也可以为A~2交配型;同一地区可以出现两种交配型,不同地区又有相同的交配型。云南西双版纳橡胶园中的分离物(P.citrophthora,P.colocasiae,P.palmivora)都表现为中性。     

Paleolimnology of Qilu Hu,Yunnan Province,China

Qilu Hu is a large (A = 36.9 km²), shallow (z_max = 6.8 m) lake that lies at an elevation of 1797 m above msl on the Yunnan Plateau, southern China. Lake waters are hard (Mg = 3.2m eq L^–1, Ca = 1.3 meq L^–1 ), fresh (conductivity = 380 S cm ^–1), and productive (Secchi < 40 cm). An 11-m sediment core has a basal ¹⁴C age of 30960 ± 860 B.P. Sediments between 11 m and 6 m are high in % dry weight, rich in clay components Al₂O₃, Fe₂O₃, K₂O, MgO, and low in organic C (6.1%), carbonate-C (<1.0%), total N (<3.2 mg g^–1), and total S (<-1.7 mg g^–1). Diatoms and pollen indicate open-water conditions between 9.0 m and 6.0 m (1342011790 B.P.). Above 6.0 m, CaCO₃ and organic matter concentrations increase relative to clastics. The transition marks a change to shallow-water conditions as inferred from diatoms and pollen, and probably reflects a shift to drier climate. Uppermost (80-0 cm) red clays were deposited rapidly, probably as a consequence of recent (decades to centuries) riparian disturbances (e.g. agriculture, lake-bottom reclamation, urban development). Dates assigned to events in the Qilu Hu profile are tentative because of potential hard-water-lake error.     

中国的被孢霉种类

被孢霉属(Mortierella Coemans)是接合菌纲(Zygomycetes)、毛霉目(Mucorales)、被孢霉科(Mortierellaceae)中的一个大属,目前已知约有90种;主要存在于土壤、植物残体、动物粪便等基物中。我国过去对被孢霉的研究不多,在《中国真菌总汇》(1979)中记录了8个种。本研究从全国22个省、市、自治区采集的2000多号样品中,分离到约220个被孢霉菌株。本研究主要采用Gams (1970, 1977)的分类系统进行分类鉴定,并对该系统进行了修改。在属下分3个亚属(Micromucor, Mortierella和Gamsiella), 8个组(Actinomortierella, Alpina,Hygrophila, Mortierella, Schmuckii, Simplex, Spinosa和Stylospora),单囊霉(Haplosporangium)被承认为独立的一个属。本研究鉴定出22个种和3个变种,包括一个新种(武夷山被孢霉Mortierella wuyishanensis sp. nov.)和一个新变种(极细无色被孢霉Mortierella hyalina(Harz) W. Gams var. subtilissima var. nov.), 14个中国新纪录。这14个新纪录为:产芽胞被孢霉(Mortierella. gemmifera M. Ellis)、园圃被孢霉(M. horticola Linnem.)、矮小被孢霉(M. humilis Linnem.)、无色被孢霉(M. hyalina(Harz) W. Gams)、印度被孢霉(M. indica B.S. Mehrotra)、英杜被孢霉(M. indohii C.Y. Chien),詹金氏被孢霉(M. jenkinii (A.L. Sm.) Naumov)、可疑极小被孢霉(M. minutissima Tiegh. var. dubia Linnem.)、易变被孢霉(M. mutabilis Linnem.)、微孢被孢霉(M. parvispora Linnem.)、角胞拉曼被孢霉(M. ramanniana(Moller) Linnem. var. angulispora (Naumov) Linnem.)、网孢被孢霉(M. reticulata Tiegh.& G. Le Monn.)、多疣被孢霉(M. verrucosa Linnem.)、轮枝被孢霉(M. verticillata Linnem.)。文中讨论和评价了一些分类性状,还列出分亚属、分组、分种和变种的检索表.每个分类单元都有描述和讨论以及线条图、并列出分布地区。     

薄鳞鱼类化石的新发现及其地层意义

本文记述了薄鳞鱼类(leptolepids)一新属新种——罗家峡隆德鱼(Longdeichthys luojiaxiaensis gen.et sp.nov.)。它和广泛分布于我国北方的另一原始真骨鱼类狼鳍鱼(Lycoptera)共生。因而,为研究真骨鱼类的演化和确定我国北方中生代含鱼岩系的时代及地层对比上,提供了新的资料。     

Nitrogen accumulation in Kaolin wastes in Cornwall

Summary Nitrogen accumulation and nitrogen mineralisation rates were measured in a series of waste heaps, produced by the china clay mining industry, which had been reclaimed at different times with a sward ofAgrostis tenuis, Festuca rubra, andTrifolium repens. The best swards tended to have high ammonification rates and rapid N turnover (which is represented by a nitrogen turnover index) —nitrification rates or nitrogen accumulation were not such good predictors of sward quality. Ammonification increased with pH and with organic nitrogen accumulation whereas N turnover was not related to these factors. Nitrification levels were generally low and it was concluded that nitrification was not important to sward health. Organic nitrogen increased with age in all swards, ammonification in certain types only and nitrification not at all. Levels of all are well short of those in adjacent grazing land. Rates of turnover had however a tendency to decline towards those in the grazings owing probably to the build up of resistant humus. The proportion of the total nitrogen which is in the biomass (30%) is also higher than in adjacent grazings (6%). Rapid nitrogen cycling is thus needed to maintain productivity and greenness, and the disadvantages of this are discussed. The adequacy of nitrogen cycle development to date is considered, and possible future strategies outlined.     

The HIV epidemic in China： history, response, and challenge

The first case of AIDS was reported in 1985 in China, but by the early 21st century, the government estimated that there were 840,000 citizens living with HIV/AIDS. The number is increasing rapidly. The major risk groups are injection drug users （IDUSs; 43%） and former plasma donors （27%）, but rates among heterosexual groups are rising rapidly. Sentinel surveillance was initiated in 1986, and now includes IDUs, men-who-have-sex-with-men, sexually transmitted disease clinic attendees, antenatal women, long-distance truck drivers, and sex workers. Although the government was slow to respond to the epidemic in the late 20th century, it has made a vigorous response in the early 21st century. Components of that response include implementation and evaluation of harm reduction programs for IDUs, education to increase knowledge and reduce stigma, treatment and social support for rural and poor HIV/AIDS patients, widespread testing, and increased funding for HIV/AIDS programs. International agencies have been generous in their support of the government initiatives. To successfully combat the epidemic, China needs to develop and train the necessary infrastructure to implement its intervention programs, particularly in the rural areas, to vigorously combat stigma and discrimination, support research especially in the universities and research institutions other than the China Centers for Disease Control, develop a system for efficient exchange of research and program information, and update legislation to reflect the current situation.     

Spectrum structures and biological functions of 8-mers in the human genome

The spectra of k-mer frequencies can reveal the structures and evolution of genome sequences. We confirmed that the trimodal spectrum of 8-mers in human genome sequences is distinguished only by CG2, CG1 and CG0 8-mer sets, containing 2,1 or 0 CpG, respectively. This phenomenon is called independent selection law. The three types of CG 8-mers were considered as different functional elements. We conjectured that (1) nucleosome binding motifs are mainly characterized by CG1 8-mers and (2) the core structural units of CpG island sequences are predominantly characterized by CG2 8-mers. To validate our conjectures, nucleosome occupied sequences and CGI sequences were extracted, then the sequence parameters were constructed through the information of the three CG 8-mer sets respectively. ROC analysis showed that CG1 8-mers are more preference in nucleosome occupied segments (AUC > 0.7) and CG2 8-mers are more preference in CGI sequences (AUC > 0.99). This validates our conjecture in principle.