长萼木通属——木通科一新属

缺瓣牛姆瓜Holboellia apetala Q．Xia,J．Z.Suen et Z．X．Peng在一系列特征上与牛姆瓜属Holboellia植物不同,不应隶属于该属,而代表了一个未被描述过的新属—长萼木通属。新属在茎、叶、果实和花的大部分特征上与木通属Akebia相似,但花萼特征又与野木瓜属Stauntonia接近,其系统位置介于这两个属之间,并偏于前者。     

帕里红景天的化学成分研究

从帕里红景天根茎的石油醚和乙醇提取部分共分得１４种结晶性化合物,经光谱分析和化学反应,分别鉴定为二十二醇、二十六酸、十九醇、β－谷甾醇、二十九醇、红景天甙、麦芽糖、棉皮素－８－葡萄糖甙、胡萝卜甙、酪醇、咖啡酸、没食子酸、形花内酯和新化合物帕里甙。     

籼稻的抗冷性与亲本的关系

四个籼稻（Ｏｒｙｚａ ｓａｔｉｖａ Ｌ．）品种幼苗经１℃黑暗或光照２５０ μｍ ｏｌ·ｍ － ２·ｓ－ １处理后,抗冷的“桂山矮选３”比不抗冷的“青华６ 号”幼苗存活率高,其子代是以“桂山矮选３”为母本的比“青华６ 号”为母本的存活率较高。抽穗期剑叶经光照低温处理１２、２４ 和３６ ｈ 后,光合作用是“桂山矮选３”和以“桂山矮选３”为母本的子代比“青华６ 号”和以“青华６ 号”为母本的子代下降较少。呼吸作用是前者比后者在处理１２ ｈ 时有明显升高现象。荧光参数Ｆｖ／Ｆｏ和Ｆｖ／Ｆｍ比值在处理２４ ｈ 时前者比后者下降明显,但在常温下恢复则是前者比后者明显较快。自然低温（寒露风）对叶绿素荧光的影响亦有相似的规律。对水稻后代的抗冷性倾向于母本进行了讨论     

鳞木目小孢子叶球山西鳞孢穗（新种）的解剖特征

描述了山西太原西山煤田太原组７号煤层煤核中一种鳞木目的小孢子叶球——山西鳞孢穗（新种）（Ｌｅｐｉｄｏｓｔｒｏｂｕｓｓｈａｎｘｉｅｎｓｅ ｓｐ． ｎｏｖ．）。其主要特征是：孢子叶球较小,长３．５ ｃｍ 以上,直径１．６～１．８ ｃｍ 。轴具管状中柱,孢子叶螺旋状着生于轴上。孢子叶柄长６～７ ｍ ｍ ,远端叶片长１．２ ｃｍ 以上。孢子叶柄具翅,翅长２～２．５ ｍ ｍ 。小孢子囊可能呈袋形,长与孢子叶柄相近,宽约４．５ ｍ ｍ ,高２～３ ｍ ｍ ,以其长度的约２／３着生于孢子叶柄的腹面上。成熟的孢子囊壁仅由一层柱状细胞构成。小孢子直径６８～７７ μｍ ,具三缝,远极面具短刺     

Characterization of a silencer element in the first exon of the human osteocalcin gene.

Osteocalcin, the major non-collagenous protein in bone, is transcribed in osteoblasts at the onset of extracellular matrix mineralization. In this study it was demonstrated that sequences located in the first exon of the human osteocalcin gene possess a differentiation-related osteocalcin silencer element (OSE). Osteocalcin was rendered transcribable in UMR-106 cells and proliferating normal osteoblasts after deletion of the -3 to +51 region. Site-specific mutagenesis of this region revealed that a 7 bp sequence (TGGCCCT) (+29 to +35) is critical for silencing function. Mobility shift assays demonstrated that a nuclear factor bound to the OSE. The OSE binding protein was present in proliferating normal pre-osteoblasts and in UMR-106 and ROS 17/2.8 osteosarcoma cells, but was absent from post-proliferative normal osteoblasts. The binding protein was inhibited by fragments containing the +29/+35 sequence, but not by other promoter fragments or by the consensus oligomers of unrelated nuclear factors AP-1 and Sp1. DNase 1 footprinting demonstrated that the OSE binding-protein protected the +17 to +36 portion of the first exon, consistent with the results of mapping studies and competitive mobility shift assays. It is hypothesized that this silencer is activated by complexing of the OSE binding protein to the OSE during the osteoblast proliferation stage and that the OSE binding protein is down-regulated at the onset of extracellular matrix mineralization.     

Site-specific cleavage of chromosomes in vitro through Cre-lox recombination.

Site-specific recombination systems are useful tools for chromosome engineering in vivo and site-specific DNA cleavage methods have applications in genome analysis and gene isolation. Here, we report a new method to fragment chromosomes in vitro using the Cre-lox site-specific recombination system. Two lox sites were targeted into the 5.7 Mb chromosomes I of Schizosaccharomyces pombe. In vitro recombination between chromosomal lox sites and exogenously provided lox oligonucleotides 'cleaved' the chromosome at the defined lox sequences. Site-specific cleavage of lox sites in the tobacco genome was also demonstrated. This recombination-based cleavage method provides a novel approach for structural and functional analyses of eukaryotic chromosomes as it allows direct isolation of chromosome regions that correspond to phenotypes revealed through Cre-lox mediated chromosome rearrangements in vivo. Moreover, recombination with end-labeled lox oligonucleotides would permit the specific end-labeling of chromosome segments to facilitate the long range mapping of chromosomes.     

Isodicentric Y chromosome: cytogenetic,molecular and clinical studies and review of the literature

Dicentrics are among the most common structural abnormalities of the human Y chromosome. Predicting the phenotypic consequences of different duplications and deletions of dicentric Y chromosomes is usually complicated by varying degrees of mosaicism (45,X cell lines), which may, in some cases, remain undetected. Molecular studies in patients with dicentric Y chromosomes have been few, and only two studies have attempted to determine the presence of SRY (the putative testis-determining factor gene). We report an 18-year-old female with short stature, amenorrhea, hirsutism, hypoplastic labia minora, and clitoromegaly who has a 45,X/46,X,idic(Y)(p11.32)/47,X,idic(Y)(p11.32),idic(Y) (p11.32) karyotype. Southern analysis using Y-specific probes (Y97, 2D6, 1F5, pY3.4) and polymerase chain reaction (PCR) analysis using primers for ZFY and SRY were positive for all loci tested, indicating that almost all of the Y chromosome was present. Our findings and an extensive review of the literature emphasize the importance of molecular analyses of abnormal Y chromosomes before any general conclusions can be reached concerning the relative effects of the Y-chromosome abnormality and mosaicism on sexual differentiation.     

Tissue specific loss of proliferative capacity of parthenogenetic cells in fetal mouse chimeras

Parthenogenetic cells are lost from fetal chimeras. This may be due to decreased proliferative potential. To address this question, we have made use of combined cell lineage and cell proliferation analysis. Thus, the incorporation of bromodeoxyuridine in S-phase was determined for both parthenogenetic and normal cells in several tissues of fetal day 13 and 17 chimeras. A pronounced reduction of bromodesoxyuridine incorporation by parthenogenetic cells at both developmental stages was only observed in cartilage. In brain, skeletal muscle, heart and intestinal epithelium, this reduction was either less pronounced or observed only at one of the developmental stages analysed. No difference between parthenogenetic and normal cells was observed in epidermis and ganglia. Our results show that a loss of proliferative potential of parthenogenetic cells during fetal development contributes to their rapid elimination in some tissues. The analysis of the fate of parthenogenetic cells in skeletal muscle and cartilage development demonstrated different selection mechanisms in these tissues. In skeletal muscle, parthenogenetic cells were largely excluded from the myogenic lineage proper by early post-midgestation. In primary hyaline cartilage, parthenogenetic cells persisted into adulthood but were lost from cartilages that undergo ossification during late fetal development.     

Argyrophilic nucleolar organizer regions

Silver staining techniques developed to demonstrate argyrophilic nucleolar organizer regions (Ag-NORs) have been widely applied in a variety of cell kinetic studies, using the mean number of AgNORs in tumour cells as a marker for malignancy of certain types of neoplasms. However, the AgNOR techniques currently available are not entirely satisfactory, as unspecific silver precipitates readily form in the sections. On the other hand, the contrast staining, may be so weak as to render identification of the AgNORs difficult. In the present study, some of the key factors influencing the outcome of AgNOR staining were evaluated in a more systematic way. A modified AgNOR staining procedure is now proposed, giving highly contrasting AgNORs with minimal unspecific silver precipitation, thus facilitating both manual and computerized counting. The new technique involves the use of microwave irradiation in order to shorten the processing time, the use of gelatin as a protective colloid, and a Farmer's solution to optimize the specificity of the technique.