Chromosome number and modal karyotype in a polysomatic endangered orchid, Bulbophyllum auricomum Lindl., the Royal Flower of Myanmar

A detailed account is presented of attendant polysomatic variation in planta and elucidation of the modal karyotype in the difficult-to-study endangered orchid Bulbophyllum auricomum, known as the Royal Flower of Myanmar. The somatic chromosome number of B. auricomum (2n?=?38) is reported for the first time. Polysomaty was prevalent in all seed-derived plants studied except two (SC34 and SC42). It was noted that in addition to normal diploid cells occurring in different frequencies (60% in SC21 to 89% in SC22, SC35), root tip cells also showed chromosome numbers <38 (in 0?C37% metaphases) and >38 (in 0?C33% metaphases). The chromosomes of B. auricomum are very small (0.7?C2.7???m) in size. The karyotype of diploid B. auricomum showed 34 chromosomes with primary constriction (14?M?+?16?m?+?4sm) and 4 chromosomes with secondary constrictions (sm:sm). Of the 50 plants analyzed, 2 (SC34 and SC42) were polyploid, showing 70 and 62 chromosomes in the root tip cells. The polyploidization in seed-derived plants clearly indicates the heterogeneous nature of orchid seed stock. Early detection of polyploidization in in vitro?Cpropagated B. auricomum is valuable for conservation of this native endangered orchid species. On the other hand, the clonally propagated plants retained the chromosomal status of parent plants. This protocol could be exploited to protect this native endangered orchid species from natural extinction.     

Genome-Wide Analysis of Cold Adaptation in Indigenous Siberian Populations

Following the dispersal out of Africa, where hominins evolved in warm environments for millions of years, our species has colonised different climate zones of the world, including high latitudes and cold environments. The extent to which human habitation in (sub-)Arctic regions has been enabled by cultural buffering, short-term acclimatization and genetic adaptations is not clearly understood. Present day indigenous populations of Siberia show a number of phenotypic features, such as increased basal metabolic rate, low serum lipid levels and increased blood pressure that have been attributed to adaptation to the extreme cold climate. In this study we introduce a dataset of 200 individuals from ten indigenous Siberian populations that were genotyped for 730,525 SNPs across the genome to identify genes and non-coding regions that have undergone unusually rapid allele frequency and long-range haplotype homozygosity change in the recent past. At least three distinct population clusters could be identified among the Siberians, each of which showed a number of unique signals of selection. A region on chromosome 11 (chr11:66–69 Mb) contained the largest amount of clustering of significant signals and also the strongest signals in all the different selection tests performed. We present a list of candidate cold adaption genes that showed significant signals of positive selection with our strongest signals associated with genes involved in energy regulation and metabolism (CPT1A, LRP5, THADA) and vascular smooth muscle contraction (PRKG1). By employing a new method that paints phased chromosome chunks by their ancestry we distinguish local Siberian-specific long-range haplotype signals from those introduced by admixture.     

Morphological studies of Asian rice and its related wild species and the recognition of a new Australian taxon

In order to clarify the taxonomy and the interrelationships among Asiatic cultivated rice, Oryza sativa , and its related wild species ( O. rufipogon, O. nivara and O . barthii ), 41 morphological characters were examined. Numerical taxonomic methods were used to analyse the data and to illustrate species relationships.
Distinctive differences among the materials studied suggest the retention of O. rufipogoon, O. nivara and O . sativa as three distinct species. The origin of O. sativa from O. nivara through domestication is discussed. An annual wild taxon from Australia, which had been classified as a form of O. nivara , is shown to be distinct from typical O. nivnra and is raised to specific rank. This species has been named O. meridionalis Ng.     

实时荧光定量PCR及其在传染性疾病检测中的应用

实时荧光定量PCR技术被广泛应用于实验研究、临床检测中。与普通的PCR相比,实时荧光定量PCR技术具有特异性强、灵敏度高、重复性好、定量准确、速度快、全封闭反应等优点。我们综述了实时荧光定量PCR技术的原理、定量方法,及其在传染性疾病检测研究中的应用。     

海南俄贤岭石灰岩山地海南大戟灌丛群落研究

根据样方调查,对海南俄贤岭自然保护区海南大戟灌丛群落的种类组成、外貌、结构特征和物种多样性进行分析。结果表明,在700m2样地中,有维管植物77种,隶属于47科70属。群落中乔木的个体数量很少,主要由灌木和草本组成,灌木层主要优势种为海南大戟等。群落外貌常绿,生活型以小高位芽为主,占22.08%;按照Raunkiaer的频度等级定律,属于B级的种类最多,频度值为43.42。整个群落的物种丰富度Magarlef指数为8.56,Shannon-Wiener指数为1.38,Simposon为0.90,均匀度指数为0.32。群落各层次的丰富度格局表现为灌木层>草本层>乔木层>藤本植物,多样性格局为灌木层>乔木层>草本层<(>)藤本植物,均匀度格局为乔木层>藤本植物>灌木层>草本层。     

Anisomycin诱导小鼠艾氏腹水癌细胞凋亡

目的：探讨Anisomycin诱导EAC细胞凋亡的机制。方法：利用MTT法观察Anisomycin对EAC细胞增殖的影响;应用An．nexinV—FITC和PI双染色检测Anisomycin作用下EAC细胞凋亡的变化;琼脂糖凝胶电泳检测Anisomycin作用下EAC细胞的DNA断裂片断;采用RT—PCR检测Anisomycin作用下Caspase-3mRNA的转录水平;WesternBlot分析Anisomycin处理的EAC细胞内Caspase-3蛋白的表达。结果：Anisomycin对EAC细胞增殖的抑制率随浓度的升高而增高,EAC细胞的凋亡水平也上升,随着Anisomycin浓度升高EAC细胞DNA断裂的寡核苷酸片段亦越趋明显,Caspase-3的mRNA和蛋白水平也上调,并明显高于阿霉素组。结论：结果表明,Anisomycin能够抑制EAC细胞的增殖,在体外可能通过激活Caspase-3凋亡信号而诱导EAC细胞的凋亡。     

Morphological forms and viability of Campylobacter species studied by electron microscopy.

Electron microscopic studies of Campylobacter revealed that different morphological forms predominate at different parts of a colony. At the periphery, cells were almost all spirals, while in the center of the colony cells were mainly coccus shaped. Unusual ring-shaped cells, "donuts", were observed in the raised, peripheral region of the colony. Donut or ring forms have not previously been reported for Campylobacter organisms. Our data indicate that young or actively growing cells are mainly spiral shaped. Older cells undergo a degenerative change to coccoid forms. The donut shape appears to be an intermediate stage between spirals and cocci. Comparisons of plate counts of actively growing and inactive cells confirmed that coccoid cells are probably nonviable.     

Direct somatic embryogenesis through thin cell layer culture in Panax ginseng

Direct somatic embryos were differentiated on cotyledon transverse Thin Cell Layers (tTCLs) of Panax ginseng after 9 weeks in the Murashige and Skoog basal (MS) medium containing 2,4-d (5M). When MS medium containing 2,4-d (5M) was used for seedling pretreatment and for tTCLs culture, somatic embryos were observed 2 weeks earlier, i.e. after 7 weeks of culture. On the tTCLs from seedlings pretreated with 2,4-d (5M) combined with benzyladenine and zeatin at 0.1 M (BZ), somatic embryos were observed after 6 weeks of culture and the percentage of embryogenesis was higher (62%) than when 2,4-d was used alone for pretreatment (40%). Similar results were also obtained from pretreatment with combinations of 2,4-d (5M) and thidiazuron (TDZ) (0.01, 0.1M). When a combination of 2,4-d (5M) and BZ (0.1M) was used both for seedling pretreatment and for tTCLs culture, both somatic embryos and shoots were observed after only 3 weeks. As the concentration of BZ increased, the percentage of somatic embryogenesis decreased but the percentage of organogenesis increased. Similar responses were obtained with a combination of 2,4-d (5M) and TDZ (0.01M). On the medium containing both NAA (0.3M) and BZ (1M), globular- and heart- stage embryos developed after 4 weeks of culture into cotyledonary-staged embryos which remained dormant after a short elongation of the embryo axis. The importance of seedling pretreatment by growth substances in enhancing somatic embryogenesis is reported.Abbreviations BA 6-benzyladenine - BZ combination of BA and zeatin - 2,4-d 2,4-dichlorophenoxyacetic acid - MS medium Murashige and Skoog basal medium - NAA a-naphthaleneacetic acid - TDZ thidiazuron - tTCLs transverse thin cell layers - TCL longitudinal thin cell layer