微核形成与细胞周期关系的初步研究 Ⅲ.丝裂霉素c诱发人淋巴细胞染色体畸变与不同周期阶段的微核形成

为了研究染色体畸变与微核形成的关系,本实验用不同浓度的丝裂霉素C(MMC,0.025—0.4μg/ml),处理人外周血淋巴细胞,观察中期染色体畸变与不同细胞周期形成的微核间的关系。获得如下主要结果:(1)MMC诱发的染色体畸变细胞率(ACF),未经培养的G_0期淋巴细胞的微核细胞率(NC-MNCF)以及培养的淋巴细胞的微核细胞率(C-MNCF),在一定剂量范围内均呈剂量依赖性增加,并可用幂回归方程描述;(2)微核形成与染色体畸变全然无关的NC-MNCF,和C-MNCF一样,与ACF呈良好的正相关;(3)用胞质分裂阻滞(CB)法,检测MMC诱发的CB-MNCF,较C-MNCF无显著提高,MNCF/ACF的比值较小,并随着MMC剂量增加从0.15左右降到0.03。所有上述结果表明,不能简单理解微核形成与染色体畸变间的关系,在分裂的细胞群体中,中期染色体畸变可能仅是微核形成的一种来源。     

Attachment of Flagellar Basal Bodies to the Cell Envelope: Specific Attachment to the Outer, Lipopolysaccharide Membrane and the Cytoplasmic Membrane

A procedure is described for the purification of the Escherichia coli outer membrane (lipopolysaccharide or L membrane) with flagella still attached. The resulting lipopolysaccharide membrane was in the form of vesicles that had a trilaminar structure in thin section and contained about 55% lipopolysaccharide and 45% protein. T2 or T4 phage preadsorbed to E. coli were found attached to the purified lipopolysaccharide membrane. Flagella were bound to the purified lipopolysaccharide membrane specifically at the basal body ring closest to the hook (the L ring). The cytoplasmic membrane in preparations from osmotically lysed E. coli spheroplasts or Bacillus subtilis protoplasts was specifically attached to flagella at the basal body ring farthest from the hook (the M ring). In the E. coli preparation, lipopolysaccharide membrane was also present and was attached to the L ring. From these data and a knowledge of the structure and dimensions of the E. coli flagellar basal body and cell envelope, a model for flagellar attachment is deduced.     

Interdependence of Cell Cycle Events in Tetrahymena thermophila: Formation of Contractile Vacuole Pore and Fission Gap in Ciliary Meridians*

SYNOPSIS The formation of the contractile vacuole pore (CVP) in Tetrahymena thermophila. genotype mol^b/mol^b is temporally and spatially associated with the formation of the fission gap in the CVP meridian. New CVPs arise when fission gaps appear in CVP meridians, the new pores being found anterior to the gaps. When, however, CVP meridians are rotated 180°, the fission gaps develop late. In more than 1/3 of the 180°-rotated CVP meridians, the new CVPs are formed before the appearance of the fission gap. Evidently, the appearance of the gap is not a prerequisite for CVP formation. Nevertheless, mutants exist in which the absence of fission gap and CVP are correlated in some cases and in which the presence of supernumerary fission gap and CVP are correlated in other instances. It is suggested that the 2 developmental events, although not causally related to each other, may be controlled by a common morpho-genetic signal. This commits a certain site (mid-body) along a ciliary meridian to develop the fission gap as well as the CVP; however, after this step of commitment, the appearance of the fission gap is delayed in 180°-rotated CVP meridians.     

Particle Assemblies in the Plasma Membrane of Tetrahymena: Relationship to Cell Surface Topography and Cellular Morphogenesis1

During a freeze-fracture electron microscopical study of the plasma membrane of Tetrahymena, several different types of organized particle assemblies were observed. Three of these were found only on the protoplasmic face and were localized in the anterior-ventral region of the cell. These consisted of plate-like arrays composed of 4–25 triplet rows of small 3–4 nm particles; long, paired linear arrays localized at the tops of cortical ridges and composed of 7–8 nm particles; and elongated tetragonal arrays located in the grooves between ridges and composed of approximately 10 nm particles. The distribution of these arrays is consistent with roles in cellular morphogenesis, chemoreception, or cell-cell pairing during conjugation. In addition, a unique particle track associated with the cytoproct (anal pore) was observed in the external face of the plasma membrane. Furthermore, the protoplasmic face of the plasma membrane is characterized by a high density of particles organized into localized microarrays, consisting of small paracrystals or strings, which exhibit a loose higher-order patterning most evident toward the anterior end of the cell. Particle distributions on the protoplasmic face do not appear to be significantly altered by conditions that cause clumping of alveolar membrane particles. Taken together, these observations are consistent with the idea that the proteins of the plasma membrane are highly ordered and relatively immobile and that the structure of the plasma membrane is regionally differentiated.     

Evidence for a Relationship Between Equine Abortion (Herpes) Virus Deoxyribonucleic Acid Synthesis and the S Phase of the KB Cell Mitotic Cycle

Autoradiographic analyses of deoxyribonucleic acid (DNA) synthesis in randomly growing KB cell cultures infected with equine abortion virus (EAV) suggested that viral DNA synthesis was initiated only at times that coincided with the entry of noninfected control cells into the S phase of the cell cycle. Synchronized cultures of KB cells were infected at different stages of the cell cycle, and rates of synthesis of cellular and viral DNA were measured. When cells were infected at different times within the S phase, viral DNA synthesis was initiated 2 to 3 hr after infection. However, when cells in G1 and G2 were infected, the initiation of viral DNA synthesis was delayed and occurred only at times corresponding to the S phase. The times when viral DNA synthesis began were independent of the time of infection and differed by as much as 5 hr, depending on the stage of the cell cycle at which cells were infected. Viral one-step growth curves were also related to the S phase in a manner which indicated a relationship between the initiation of viral DNA synthesis and the S phase. These data support the concept that initiation of EAV DNA synthesis is dependent upon some cellular function(s) which is related to the S phase of the cell cycle.     

Relationship Between N:P Ratio and Growth Rate During the Life Cycle of Calanoid Copepods: An in situ Measurement

The mean nitrogen and phosphorus contents of the calanoid copepodMixodiaptomus laciniatus Lilljeborg were measured to the stagelevel throughout the ice-free period of a high mountain lake.Our results indicate large intraspecific variations in calanoidelemental composition. While mean N as dry weight increasedfrom 3.0 ± 1.3 in nauplii to 6.0 ± 2.1 in copepodites,mean P content showed the opposite trend, varying intraspecificallyfrom 0.98 ± 0.26% in nauplii, to 0.87 ± 0.21%in copepodites and 0.51 ± 0.16% in adults. Thus, themean N:P ratio increased ontogenetically from 3.3 in naupliito 13.3 in copepodites and 24.6 in adults. Two ontogenetic parameters,the growth rate and body size, were associated with zooplanktonstoichiometry. Among all 11 copepod stages, growth rate waspositively related to %P and negatively related to %N and N:Pratio. A two-part analysis of these relationships, before andafter metamorphosis, showed that the nauplii growth rate explainednearly all the variance in naupliar P content. A high P contentin nauplii may reflect a high content of RNA, translating intorapid growth rates. Overall, these results tend to support thehypothesis linking specific growth rate with P content for copepods,but these results also suggest that the validity of this hypothesisis robustness when differences in the life history of copepodsas a consequence of metamorphosis are accounted for. We suggestthat the intra-stage variation in P content is associated withpeaks of intensive metabolic activity during the process ofmolting in copepods, and we emphasize the importance of newempirical evidence to examine this hypothesis further.     

角倍蚜干母种群的空间格局及其形成机理研究

对角倍蚜Schlechtendalia chinensis(Bell)干母种群的空间格局及其形成机理的研究表明,角倍蚜干母种群在倍林间呈聚集分布．导致其聚集分布的原因是角倍蚜本身的聚集行为和盐肤木Rhus chinensts Mill复叶生长状况的异质性两个方面：角倍蚜干母种群分布的基本成分是琉松个体群,个体群的大小为3—6株倍树所占的面积(2．3—4．6m^2);当样方大小为1、3、6株时为聚集分布,大于6株时为均匀分布。     

Secretory Pattern of Inhibin During Estrous Cycle and Pregnancy in African (Loxodonta africana) and Asian (Elephas maximus) Elephants

The ovary of female elephants has multiple corpora lutea (CL) during the estrous cycle and gestation. The previous reports clearly demonstrated that inhibin was secreted from lutein cells as well as granulosa cells of antral follicles in cyclic Asian elephants. The aim of this study is to investigate the inhibin secretion during the pregnancy in African and Asian elephants. Two African elephants and two Asian elephants were subjected to this study. Circulating levels of immunoreactive (ir‐) inhibin and progesterone were measured by radioimmunoassay. Four pregnant periods of an African elephant and three pregnant periods of an Asian elephant were analyzed in this study. Circulating levels of ir‐inhibin started to increase at 1 or 2 week before the ovulation and reached the peak level 3 or 4 weeks earlier than progesterone during the estrous cycle in both African and Asian elephants. After last luteal phase, the serum levels of ir‐inhibin remained low throughout pregnancy in both an African and an Asian elephant. The mean levels of ir‐inhibin during the pregnancy were lower than the luteal phase in the estrous cycle despite high progesterone levels were maintained throughout the pregnancy. These results strongly suggest that CL secrete a large amount of progesterone but not inhibin during the pregnancy in elephants. Zoo Biol 31:511‐522, 2012. © 2011 Wiley Periodicals, Inc.     

The Arabidopsis APC4 subunit of the anaphase-promoting complex/cyclosome (APC/C) is critical for both female gametogenesis and embryogenesis

The anaphase‐promoting complex/cyclosome (APC/C) is an E3 ubiquitin ligase that is involved in regulating cell‐cycle progression. It has been widely studied in yeast and animal cells, but the function and regulation of the APC/C in plant cells are largely unknown. The Arabidopsis APC/C comprises at least 11 subunits, only a few of which have been studied in detail. APC4 is proposed to be a connector in the APC/C in yeast and animals. Here, we report the functional characterization of the Arabidopsis APC4 protein. We examined three heterozygous plant lines carrying apc4 alleles. These plants showed pleiotropic developmental defects in reproductive processes, including abnormal nuclear behavior in the developing embryo sac and aberrant cell division in embryos; these phenotypes differ from those reported for mutants of other subunits. Some ovules and embryos of apc4/+ plants also accumulated cyclin B protein, a known substrate of APC/C, suggesting a compromised function of APC/C. Arabidopsis APC4 was expressed in meristematic cells of seedlings, ovules in pistils and embryos in siliques, and was mainly localized in the nucleus. Additionally, the distribution of auxin was distorted in some embryos of apc4/+ plants. Our results indicate that Arabidopsis APC4 plays critical roles in female gametogenesis and embryogenesis, possibly as a connector in APC/C, and that regulation of auxin distribution may be involved in these processes.     

Relationship Between Ethylene Release,Membrane Permeability and Activity of Polyphenol Oxidase Changes of Duck (Pears Pyrus bretschnideri Rehder) During Low Temperature Storage

Duck pear (Pyrus bretschneideri Rehder) tends to develop browning core after 55 to 60 days storage at low temperature (0℃). Following physiological changes of the duck pear during storage at different temperature were investigated: (1) As compared with 20℃, ethylene release is obviously decreased and its peak is retarded for 15 days at 0℃. Levels of internal ethylene are variant at different individuals harvested at same time. Concentrations of internal ethylene are in accord with ethylene release. The higher internal ethylene is, the easier the pear core becomes brown. (2) At 0℃, activity of polyphenol oxidase in the core increases with ethylene release enhancement. After ethylene peak passes, its activity is lower than before. (3) The electric conductivity of cores is higher at 0℃ than at 20℃. During post climacteric period, the electric conductivity increases irreversibly, then browning core occurs. From above results, it is concluded that interactions between two factors induce the browrang core of the duck pears at low temperature. One is chilling injury caused by low temperature, another is ethylene function. They stimulate the activity of polyphenol oxidase and enhance the membrane permeability.     

Relationship Between Endopeptidase and H2O2 During the Aging of Wheat Leaf (in English)

The relationship between hydrogen peroxide (H2O2) and endopeptidase（EP） in wheat (Triticum aestivum L. cv. Yanmai 158) leaves was studied during natural and artificial aging. Rapid accumulation of endogenous H2O2 and marked increase of EP activity were observed during the later phase of aging. A new EP isozyme with higher activity was detected by electrophoresis on polyacrylamide gels containing denatured heamoglobin. With the increase of exogenous H2O2, the activity of EP increased at first and then decreased.     

Induced life cycle transition from holocycly to anholocycly of the Russian wheat aphid (Homoptera: Aphididae)

The Russian wheat aphid (RWA), Diuraphis noxia (Mordvilko), exists with holocyclic life cycle in Tacheng, Xinjiang in Northwest China. It produces males and oviparae to mate and oviposit for overwintering by eggs. Under laboratory conditions with 14 h/d photophase and temperature not lower than 15℃, RWA occurred in parthenogenesis and produced no males. The laboratory populations of Russian wheat aphid, which were kept under natural conditions in fall by 15th, 49th and 81st generation while wild populations produced males and oviparae for mating, produced males and oviparae with their number decreased gradually, but viviparae and nymphs increased sequentially. As a result, it produced a small amount of oviparae and no males emerged in fields by 49 generations' reproduction in laboratory. After development of 81 generations, oviparae happened occasionally and no eggs occurred for overwintering instead of viviparae and nymphs. A hypothesis of RWA disastrous process was proposed. The life cycle of RWA can     

Overexpression of DOC-1R Inhibits Cell Cycle G1/S Transition by Repressing CDK2 Expression and Activation

DOC-1R (deleted in oral cancer-1 related) is a novel putative tumor suppressor. This study investigated DOC-1R antitumor activity and the underlying molecular mechanisms. Cell phenotypes were assessed using flow cytometry, BrdU incorporation and CDK2 kinase assays in DOC-1R overexpressing HeLa cells. In addition, RT-PCR and Western blot assays were used to detect underlying molecular changes in these cells. The interaction between DOC-1R and CDK2 proteins was assayed by GST pull-down and immunoprecipitation-Western blot assays. The data showed that DOC-1R overexpression inhibited G1/S phase transition, DNA replication and suppressed CDK2 activity. Molecularly, DOC-1R inhibited CDK2 expression at the mRNA and protein levels, and there were decreased levels of G1-phase cyclins (cyclin D1 and E) and elevated levels of p21, p27, and p53 proteins. Meanwhile, DOC-1R associated with CDK2 and inhibited CDK2 activation by obstructing its association with cyclin E and A. In conclusion, the antitumor effects of DOC-1R may be mediated by negatively regulating G1 phase progression and G1/S transition through inhibiting CDK2 expression and activation.     

乌天麻Gastrodianin基因的鉴定及其在天麻发育进程中的表达

基于相似性克隆策略和RT-PCR,从兰科植物乌天麻(Gastrodia elataf.glauca)球茎克隆得到两个新的天麻抗真菌蛋白基因,命名为gastrodianin-4A(ga4A)和gastrodianin-4B(ga4B),并首次用Northern杂交研究了该基因在植物不同部位的转录表达。结果表明,天麻个体的不同部位只转录表达同一种Gastrodianin基因,纯化自球茎的Gastrodianin蛋白质的肽质量指纹谱与推导的Ga4A和Ga4B成熟蛋白的氨基酸序列相吻合;Northern杂交证明天麻的地上器官Gastrodianin基因转录表达量远远高于地下球茎,而次生球茎皮层组织的表达量比中柱和整个营繁茎的都高一些。天麻球茎Gastrodianin的外周表达模式可能是天麻在地下抵御蜜环菌(Armillaria mellea Karst)入侵球茎皮层内部的防卫机制之一,但该基因在天麻地上部分的高丰度表达暗示Gastrodianin可能蕴藏其它生理功能。     

Patterns of spatial and temporal cranial muscle development in the African clawed frog, Xenopus laevis (Anura: Pipidae)

The African Clawed Toad, Xenopus laevis, has been a major vertebrate model organism for developmental studies for half a century. Because most studies have focused on the early stages of development, this has had the effect that many aspects of organogenesis and later development remain relatively poorly known in this species. In particular, little is known about cranial muscle development even at the level of morphology and histological differentiation of muscle anlagen and muscle fibers. In this study, we document the morphogenesis and histological differentiation of cranial muscles in X. laevis. We provide a detailed account of the timing of development for each of the cranial muscles, and also describe a new muscle, the m. transversus anterior. The cranial musculature of X. laevis larvae generally develops in a rostrocaudal sequence. The first muscles to differentiate are the extrinsic eye muscles. Muscles of the mandibular and hyoid arches develop almost simultaneously, and are followed by the muscles of the branchial arches and the larynx, and by the mm. geniohyoideus and rectus cervicis. Despite the fact that differentiation starts at different stages in the different muscles, most are fully developed at Stage 14. These baseline data on the timing of muscle differentiation in the X. laevis can serve as a foundation for comparative studies of heterochronic changes in cranial muscle development in frogs and other lissamphibians.     

受精前后梨子房(幼果)中钙与内源激素含量的关系

受精促进子房(幼果)对钙的吸收,受精完成后的黄花子房(幼果)中钙含量迅速上升,未受精的子房(幼果)中钙含量远低于同期受精的果实.受精前后钙含量变化与其中IAA和GA3含量变化相似;NAA、GA3处理促进钙的吸收.IAA和GA3可能同时参与受精前后树体中的钙向幼果(子房)的运输过程.     

尖叶拟船叶藓营养元素生殖配置格局

为了揭示尖叶拟船叶藓营养元素生殖配置规律,本文对其12种营养元素的生殖配置格局和季节动态进行了研究。其结果如下：成熟孢子体的生物量配置为6．67％;在成熟孢子体中12种营养元素的含量顺序是：C（452mg／g）〉N（35mg／g）〉K（8439．9μg／g）〉Ca（7012．9μg／g）〉P（2129．2μg／g）〉Mg（1482．9μg／g）〉Na（432．9μg／g）〉Mn（196．3μg／g）〉Fe（177．7μg／g）〉Al（174．8μg／g）〉Zn（68．1μg／g）〉Cu（19．4μg/g）;成熟孢子体中营养元素生殖配置顺序是：K（17．7％）〉P（15．1％）〉Cu（13．3％）〉N（11．6％）〉Na（10．5％）〉Mn（7．8％）〉Zn（7．5％）〉C（6．9％）〉Mg（6．8％）〉Ca（5．4％）〉Fe（1．3％）〉Al（1．2％）。     

桃儿七不同器官中营养成分分布状况及其生态学意义

植物生殖生态学是植物学领域中刚刚兴起并迅速发展的学科 ,近年来生活史进化理论的研究 ,使繁殖分配 (ｒｅｐｒｏｄｕｃｔｉｖｅａｌｌｏｃａｔｉｏｎ (ＲＡ ) )与繁殖投资(ｒｅｐｒｏｄｕｃｔｉｖｅｅｆｆｏｒｔ (ＲＥ) )研究成为植物生态学研究的主要焦点[7] 。目前在植物繁殖分配与繁殖投资研究中 ,通常用生物量作为衡量指标 ,这种方法遇到两个疑难问题 :一是各种成分在植物器官中的含量及比例各不相同 ,而且各种成分在植物生长发育过程中所起的生理功能也是不等价的 ,因此 ,在重量相同时 ,各器官的综合营养价值及生理功能是不等价的 ,生…     

Cold Acclimation in Plants: Relationship Between the Lipid Composition and the Cryostability of the Plasma Membrane

Received 23 March 1999/ Accepted in revised form 9 April 1999