心脏基因转录潜能的区域化

心脏基因在心肌中的区域化表达是一个非常普遍的现象,通过转基因动物研究心肌中的转录潜能的区域化已取得了重大的进展.房室转录区域化最早是在线状心管形成时开始出现的.之后,在胚胎心脏的各个部分均可以发现转基因区域化表达.对于转基因在心肌中区域化表达的分子机理的研究,现在主要集中在对转基因调控区域的顺式调控元件和反式调控元件的解析,以及在心肌细胞中对于转录很重要的基因或是已被证明会介导位置信息的基因的表达模式和功能的研究上.     

秦岭种子植物区系分区研究

在吴征镒1983年中国植物区系分区的基础上,依据秦岭山地的自然环境特点,并结合植被优势种及区系特有种和特征种的分布情况,按照发生学原则,将秦岭种子植物区系划分为两大植物地区,五个植物亚地区,七个植物省,并对每个植物省区系的特点进行了分析,结果进一步证明秦岭是我国植物区系南北分异的一条主要界限。     

Biogeographical network analysis of plant species distribution in the Mediterranean region

The delimitation of bioregions helps to understand historical and ecological drivers of species distribution. In this work, we performed a network analysis of the spatial distribution patterns of plants in south of France (Languedoc‐Roussillon and Provence‐Alpes‐Côte d'Azur) to analyze the biogeographical structure of the French Mediterranean flora at different scales. We used a network approach to identify and characterize biogeographical regions, based on a large database containing 2.5 million of geolocalized plant records corresponding to more than 3,500 plant species. This methodology is performed following five steps, from the biogeographical bipartite network construction to the identification of biogeographical regions under the form of spatial network communities, the analysis of their interactions, and the identification of clusters of plant species based on the species contribution to the biogeographical regions. First, we identified two sub‐networks that distinguish Mediterranean and temperate biota. Then, we separated eight statistically significant bioregions that present a complex spatial structure. Some of them are spatially well delimited and match with particular geological entities. On the other hand, fuzzy transitions arise between adjacent bioregions that share a common geological setting, but are spread along a climatic gradient. The proposed network approach illustrates the biogeographical structure of the flora in southern France and provides precise insights into the relationships between bioregions. This approach sheds light on ecological drivers shaping the distribution of Mediterranean biota: The interplay between a climatic gradient and geological substrate shapes biodiversity patterns. Finally, this work exemplifies why fragmented distributions are common in the Mediterranean region, isolating groups of species that share a similar eco‐evolutionary history.     

Fate mapping study of the endoderm in the posterior part of the 1.5-day-old chick embryo

Various endodermal sites posterior to the caudal-most somite were marked in ovo with the vital dye Dil, and the fate of marked endoderm was analyzed after 2 or 3 days' reincubation. The endoderm in this area became gut epithelium posterior to the caudal jejunum and yolk sac. The area occupied by the cells that were to contribute to the dorsal part of the digestive tube lay centrally around the area overlaid by axial and paraxial mesoderm, with the preventral digestive area lying outside with considerable overlapping, which was surrounded by the preyolk sac area. During the formation of the posterior digestive tube, the endoderm was elongated anteroposteriorly to a considerable degree. Cells that contributed to the cloaca and those that produced descendants in the large intestine occupied similar areas posterior to the center of the sinus rhomboidalis, which were included in the pre-ileal area extending more anteriorly. Prejejunal cells generally localized in a more anterior position than pre-ileal cells. Pre-allantoic cells were located in a rather small area around the posterior primitive streak.     

黄土高原东北缘的鼠类及某区划的研究

位于山西省东北部和河北省冀北山地张家口的黄土高原东北缘地区的鼠类,过去曾经有Thomas(1908;1909)、Allen(1938;1940)、Ho(何锡瑞,1934)、张俊等(1965)、郑宝赉等(1966)、柳枢(1977)、梁俊勋(1983)等报道。     

The Floristic Characteristics and Geographical Distribution of the Rosaceae in Xizang

The Rosaceae is one of the five largest families of Xizang flora, consisting of 30 genera with 242 species, the total number of species is slightly less than those of Compositae, Graminae, Leguminosae and Ericaceae in Xizang, amounting to 62.5% of the total number of genera and 28% of the total number of species of the rosaceous flora in China. The four subfamilies of Rosaceae including primitive, intermediate and advanced groups have been found in Xizang. These groups consist of 11 types of floristic elements, i.e. 4 genera belong to cosmopolitan, 9 genera belong to North Temperate, 3, E. Asian-N. American, 3 Sino-Himalayan, 3 Sino-Japanesa, 2 Old World Temperate, 1 Temperate Asian, 2 Mediterranean-W. and O. Asian, 1 C. Asian, I Tropical Asian and 1 endemic to China. It is obvious that Rosaceae in Xizang comprises holarctic, Ancient Mediterranean and paleotropical elements, among which the temperate components are the most dominant. The characteristics of the floristic composition of Rosaceae in Xizang may be summarized as follows: (1) Xizang abounds in both genera and species of the family which are diverse in forms, including the primitive, intermediate and advanced groups, (2) The geographical elements are rather complex, mostly belonging to the temperate, among which the Sino- Himalayan components and the elements endemic to China are dominant, (3) The proportion of plants endemic to China and distributed in Xizang is much higher than those endemic to Xizang itself, but there exist newly arisen species and infraspecific forms or varieties which show that the speciation is apparently still active in Xizang. The rosaceous flora of Xizang is a combination of old and new floristic elements, based on the old floristic components, affected by the upheaval of the Himalayas, the differentiation and speciation have been taking place in the long history. The geographical distribution of Rosaceae in Xizang may be divided into 5 regions, i.e. the northeastern, southeastern, southern, northwestern and northern. The rosaceous plants are most abundant in the southeastern area, next in southern area, fewer in the northeastern and very rare in the northwestern and northern regions. The general tendency of the distribution of Rosaceae in Xizang is that the number of species gradually decreases from the southeast to the northwest and the habit gradually changes from trees, shrubs and herbaceous plants in the southeast to cushion-like scrubs and dwarf perennial herbs in the northwest. These facts clearly show that the uplift of the Himalayas has deeply affected the phytogeographical distribution of Xizang Rosaceae. The rosaceous flora of Xizang has close relationships with those of the adjoring regions, i.e. Yunnan and Sichuan. Besides, it is connected with floras of Nepal, Sikkim, Bhutan nothern Buram and nothern India, but silghtly influenced by the Ancient Mediterranean flora.     

Notes on the key role of stenochoric endemic plants in the floristic regionalization of Yunnan

With the accumulation and accessibility of information about plant species, it is time to re-evaluate and further divide a global biodiversity hotspot region, Yunnan, located in southwestern China. In this study, we combined data on the distribution of 1010 stenochoric endemic seed plants, vegetation constitution, geological history and climate change, and used these to propose a new system of floristic regions. We identified 11 distinct floristic subregions and 84 floristic provinces within Yunnan. Our work confirmed some views emphasized by Wu Zhengyi that the stenochoric endemic species play a key role in defining floristic provinces; that stenochoric endemic plants with long collection and publication histories are more valuable; that greater attention should be paid to woody plants; and that for Yunnan, a border region, some trans-border distributed elements should be treated cautiously.     

青海湟水流域植物区系研究

湟水流域位于青海省的东部,约处于北纬35°56′～37°38′,东经100°35′～103°05′。属于青藏高原和黄土高原的过渡地带,海拔1650～4395m,全区面积约16600km~2,属于大陆性气候和高原大陆性气候类型。本区共有野生种子植物83科、400属、1234种。分别占本区所属的青藏高原植物亚区唐古特地区总科数的92.22％、总属数的78.74％、总种数的54.00％。研究表明,湟水流域植物区系特征为:①在唐古特地区中种类相对较丰富;②温带成分占92.80％,以绝对优势确定了本区系为明显的温带性质(属于以北温带成分,特别是欧亚大陆温、寒地带典型成分为优势的,兼具温性、寒温和高寒类型的温带区系性质,或可称为在温带区系中的过渡区系所具有的“复合型”区系特征);③木本类型少,大多数种类为多年生草本植物,缺乏古老和原始类群,一些中国特有种衍生于其广布的亲缘种中,表明本区系具有年轻和衍生的性质;④我国西南高山区系和华北区系对该区系具有双重影响;⑤为青藏高原植物亚区唐古特植物地区同华北植物地区相互过渡的代表区系之一;⑥特有属和特有种少。在中国种子植物区系分区中,本区属于青藏高原植物亚区中的唐古特地区。     

世界生态旅游区划

生态旅游区划是揭示全球尺度生态旅游资源与生态旅游业空间布局的重要手段,有助于从整体上把握世界生态旅游的发展。本文在探讨生态旅游区划定义与理论依据的基础上,提出生态旅游区划的理论基础是地域分异规律与生态学原理,并根据全局谋划、综合分析、主导因索、与行政区协调、兼顾自然区划等原则。将世界生态旅游地域系统划分为6个生态旅游洲、29个生态旅游大区、71个生态旅游区以及若干生态旅游地。文章还对各洲的生态旅游特点进行了阐述。