塞舌尔角毛藻的形态学再描述和分子系统学分析

塞舌尔角毛藻(Chaetoceros seychellarus)属于硅藻门角毛藻属有色角毛藻亚属,为全球罕见种。以往有关塞舌尔角毛藻的研究报道多限于光学显微镜观察,对其形态学认知仍不完整,系统学研究也尚属空白。本文从我国台湾海峡和海南岛三亚海域采集了塞舌尔角毛藻,并在实验室建立了单克隆培养株系,利用光镜、扫描电镜对其形态学特征进行了较为详尽的观察,基于核糖体大亚基(large subunit ribosomal DNA)D1~D3区序列,分析了其系统学信息。塞舌尔角毛藻的典型特征是链状群体直,窗孔呈矩形,壳面具有两个唇形突。分子系统树显示,塞舌尔角毛藻与丹麦角毛藻构成姐妹支,依据形态学建立的北方组呈现多系起源,后续有待加以修订。

Modern pollen assemblages of the forest communities and their relationships with vegetation and climate in northern China

53 pollen traps and surface samples were collected in order to detect the characteristics of pollen assemblages and their relationships with vegetation and climate in 16 forest communities located in 10 mountains in northern China. The results show that 72% of the pollen taxa (80 taxa) are the same between the traps and the surface samples. The dominant taxa in the plant communities are consistent with the main pollen taxa in the pollen assemblages at the same sites. In Pinus plant communities, both Pinus pollen influx and concentration are higher, indicating the high pollen productivity and good pollen preservation ability of Pinus. In Picea and Abies plant communities, Picea and Abies have lower pollen influxes but higher concentrations, suggesting their low pollen productivities but better pollen preservation abilities. In Betula and Quercus plant communities, Betula and Quercus have higher pollen influxes but lower concentrations, revealing their high pollen productivities but poor pollen preservation abilities. The study of relationships between pollen and vegetation with discriminant analysis shows that pollen assemblages from both trap and surface samples can reflect the characteristics of different communities and distinguish different ecological areas, but surface samples can reflect the dominant components of communities much better than the traps. The study on correlations between pollen assemblages and climate with DCCA reveals that significant correlations exist between pollen assemblages and mean temperature of the coldest month (r = 0.84 for trap samples, r = 0.72 for surface samples), and then annual mean precipitation (r = 0.73 for trap samples, r = 0.71 for surface samples).

Molecular Characterization of Segments S7 to S10 of a Southern Rice Black-streaked Dwarf Virus Isolate from Maize in Northern China

Southern rice black-streaked dwarf virus (SRBSDV) is a novel Fijivirus prevalent in rice in southern and central China,and northern Vietnam. Its genome has 10 segments of double-stranded RNA named S1 to S10 according to their size. An isolate of SRBSDV,JNi4,was obtained from naturally infected maize plants from Ji'ning,Shandong province,in the 2008 maize season. Segments S7 to S10 of JNi4 share nucleotide identities of 72.6%-73.1%,72.3%-73%,73.9%-74.5% and 77.3%-79%,respectively,with corresponding segments of Rice black-streaked dwarf virus isolates,and identities of 99.7%,99.1%-99.7%,98.9%-99.5%,and 98.6%-99.2% with those of SRBSDV isolates HN and GD. JNi4 forms a separate branch with GD and HN in the phylogenetic trees constructed with genomic sequences of S7 to S10. These results confirm the proposed taxonomic status of SRBSDV as a distinct species of the genus Fijivirus and indicate that JNi4 is an isolate of SRBSDV. Shandong is so far the northernmost region where SRBSDV is found in China.

Seasonal variation in species composition and abundance of demersal fish and invertebrates in a Seagrass Natural Reserve on the eastern coast of the Shandong Peninsula,China

Seagrass habitats are structurally complex ecosystems, which support high productivity and biodiversity. In temperate systems the density of seagrass may change seasonally, and this may influence the associated fish and invertebrate community. Little is known about the role of seagrass beds as possible nursery areas for fish and invertebrates in China. To study the functioning of a seagrass habitat in northern China, demersal fish and invertebrates were collected monthly using traps, from February 2009 to January 2010. The density, leaf length and biomass of the dominant seagrass Zostera marina and water temperature were also measured. The study was conducted in a Seagrass Natural Reserve(SNR) on the eastern coast of the Shandong Peninsula, China. A total of 22 fish species and five invertebrate species were recorded over the year. The dominant fish species were Synechogobius ommaturus, Sebastes schlegelii, Pholis fangi, Pagrus major and Hexagrammos otakii and these species accounted for 87% of the total number of fish. The dominant invertebrate species were Charybdis japonica and Octopus variabilis and these accounted for 98% of the total abundance of invertebrates. There was high temporal variation in species composition and abundance. The peak number of fish species occurred in August–October 2009, while the number of individual fish and biomass was highest during November 2009. Invertebrate numbers and biomass was highest in March, April, July and September 2009. Temporal changes in species abundance of fishes and invertebrates corresponded with changes in the shoot density and leaf length of the seagrass, Zostera marina.

国家甘薯品种区域试验——宝鸡综合试验站

宝鸡综合试验站是国家甘薯产业技术体系设立的综合试验站之一。本试验通过对10个淀粉型专用甘薯品种在北方进行区域试验,在丰产性、稳定性、干率、适应性及抗逆性等方面进行比较,为品种参加国家区域试验等升级试验提供科学依据。

An introductory report on the biodiversity of Middle Jurassic Phoenicopsis(Czekanowskiales) from the Ordos Basin, China

Although the genus Phoenicopsis is the most common member of Czekanowskiales and is considered an indicative representative of the Middle Jurassic Coniopteris–Phoenicopsis assemblage in northern China, little was known about its taxonomy and biodiversity based upon the leaf cuticular structure. In this paper, three subgenera of the genus Phoenicopsis from the Middle Jurassic, Yan'an Formation of the Ordos Basin, China, Phoenicopsis(subg. Phoenicopsis)(Heer) Samylina, P.(subg. Windwardia)(Florin) Samylina and P.(subg. Culgoweria)(Florin) Samylina are identified based upon the leaf epidermal features for the first time. This discovery demonstrates that Phoenicopsis was quite diverse during the Middle Jurassic in northern China. Its biodiversity is significant for further understanding Middle Jurassic paleophytogeography and paleoclimatology of northern China. The current findings show that the three Phoenicopsis subgenera coexisted and flourished in the mixed zone(ecotone) between the Indo-Sinian Floristic Region and the Siberian Floristic Region as seasonal deciduous plants(trees or shrubs) during the Middle Jurassic. They were important elements in the Middle Jurassic deciduous gymnospermous forest community in warm temperate regions with seasonal temperature and precipitation variations. They are interpreted as growing on the hillsides and sloping fields along meandering streams, lakes and swamps in a vast sedimentary basin in a wet and warm environment.