Brachiopod Metabolism and Enzymes

Brachiopods consume oxygen at relatively low rates, and sometimesconsume none at all for hours. Specimens of Terebratulina septentrionalissurvived total anoxia for 3.5 days at 3°C. Isolated tissuesconverted ¹⁴Cµglucose into eight carboxylic acids at anaverage rate of 1.5 x 10^–10 mole/SOL;hr per g tissue.Carbon from labelled glucose flowed steadily into citric acidand into an unknown acid for 2 hours under both aerobic andanaerobic conditions. In the first hour, more label was foundin malic acid after aerobic incubation, and more label in succinicacid after anaerobic incubation, while the fraction in lacticacid was the same. Terebratulina carried on a mixed fermentationboth in the presence and in the absence of oxygen. The inarticulate Glottidia pyramidata has a succinate dehydrogenasewith kinetic properties favoring succinate oxidation, whilethe Terebratulina enzyme is more likely to operate in the reversedirection. Lactate metabolism is relatively unimportant in bothspecies. Information on nitrogen-compound metabolism is limited to theinarticulate Lingula reevii, which is ammonotelic. Arginaseand urease activities exceeded those of bivalve mollusks, whileaspartate and alanine aminotransferase rates were both muchlower. Some unique features of DNA, RNA and hemerythrin fromLingula have been discovered in the last few years.     

Age, Growth and Shape of the Intertidal Brachiopod Waltonia inconspicua Sowerby, from New Zealand

Using large samples from six localities in New Zealand, thepopulation structure and longevity of the intertidal brachiopodWahonia inconspicua Sowerby has been established. The populationis one containing two modes. The first year group extends upto 3.0 mm shell length and together with the second year groupconstitutes the first mode of the length distribution histogram.Reproduction commences at approximately 10 mm length or duringthe fourth year and at this stage the second mode is formedby the overlap of year groups of mature animals. In Otago HarbourW. inconspicua was found to live up to eight years and occasionallysurvive for as long as 15 years. Growth is slow and unevenly distributed through life, beingfastest during the first four years and decreasing after reproductioncommences. Two years later, at approximately 15 mm shell lengththere is a further reduction in growth rate, and when the animalreaches 17 mm length it slows yet again and becomes very smallin senescence. However, egg production at this stage is veryhigh being greater than 18,000 per year. The rate and type of growth varies considerably between localities.Rough water conditions cause slower growth and more gibbousform, and phenotypic stunting appears to have occurred.     

钙离子对鼠角质细胞生长和分化的影响

用无血清培养基培养角质细胞,研究了Ca²⁺对鼠角质细胞生长和分化的影响。实验结果表明,培养基中钙离子最佳浓度为0.2mmol/L。在此浓度下,细胞克隆形成率达到10.8%,细胞的贴壁率达到28.7%,细胞的分化比例和老化比例分别为5.4%和26.3%;当Ca²⁺浓度达到0.6mmol/L以上时,则会引起角质细胞显著的分化和老化。     

Cell Cycle–Dependent Differentiation Dynamics Balances Growth and Endocrine Differentiation in the Pancreas

Organogenesis relies on the spatiotemporal balancing of differentiation and proliferation driven by an expanding pool of progenitor cells. In the mouse pancreas, lineage tracing at the population level has shown that the expanding pancreas progenitors can initially give rise to all endocrine, ductal, and acinar cells but become bipotent by embryonic day 13.5, giving rise to endocrine cells and ductal cells. However, the dynamics of individual progenitors balancing self-renewal and lineage-specific differentiation has never been described. Using three-dimensional live imaging and in vivo clonal analysis, we reveal the contribution of individual cells to the global behaviour and demonstrate three modes of progenitor divisions: symmetric renewing, symmetric endocrinogenic, and asymmetric generating a progenitor and an endocrine progenitor. Quantitative analysis shows that the endocrine differentiation process is consistent with a simple model of cell cycle–dependent stochastic priming of progenitors to endocrine fate. The findings provide insights to define control parameters to optimize the generation of β-cells in vitro.     

生长分化因子5与代谢性疾病

生长分化因子5 (growth/differentiation factor-5,GDF-5)属于转化生长因子β (transforming growth factor-β,TGF-β)家族,在骨、软骨、心脏、大脑、肾脏、骨骼肌和肌腱、肝脏以及脂肪等多个器官组织中表达。GDF-5与其受体BMPR-I/BMPR-II结合,激活Smad1/5/8、PI3K/Akt、p38-MAPK等信号,发挥促进细胞增殖分化、减少氧化应激损伤、细胞凋亡和组织纤维化等生物学功能。目前针对GDF-5的研究多聚焦在骨、软骨与肌腱的生长和修复等方面,而在其他器官中的生物学作用鲜有报道。因此,本文通过梳理和总结近年来GDF-5与代谢性疾病的研究进展,为GDF-5在改善代谢性疾病防治提供新的见解和理论依据。     

文心兰试管苗分化及育苗技术研究

文心兰原球茎分化苗过渡驯化培养试验表明,改良1号+椰子汁100g/L的培养基有利于原球茎分化成苗,能促进分化苗生长健壮、整齐度好。壮苗与生根培养试验表明,以改良1号为基本培养基,加入香蕉泥100g/L、活性炭1g/L,在较强光照(2 000~3 000 lx)下培养,植株各项生长指标表现较好,有利于后期炼苗成活;以三角瓶为定瓶容器培养,植株接种效率最高、污染率最低;选取3cm高的植株定瓶,可显著提高文心兰工厂化组培育苗的工作效率。     

Brachiopod shell thickness links environment and evolution

While it is well established that the shapes and sizes of shells are strongly phylogenetically controlled, little is known about the phylogenetic constraints on shell thickness. Yet, shell thickness is likely to be sensitive to environmental fluctuations and has the potential to illuminate environmental perturbations through deep time. Here we systematically quantify the thickness of the anterior brachiopod shell which protects the filtration chamber and is thus considered functionally homologous across higher taxa of brachiopods. Our data come from 66 genera and 10 different orders and shows well-defined upper and lower boundaries of anterior shell thickness. For Ordovician and Silurian brachiopods we find significant order-level differences and a trend of increasing shell thickness with water depth. Modern (Cenozoic) brachiopods, by comparison, fall into the lower half of observed shell thicknesses. Among Ordovician–Silurian brachiopods, older stocks commonly have thicker shells, and thick-shelled taxa contributed more prominently to the Great Ordovician Biodiversification but suffered more severely during the Late Ordovician Mass Extinction. Our data highlight a significant reduction in maximum and minimum shell thickness following the Late Ordovician mass extinction. This points towards stronger selection pressure for energy-efficient shell secretion during times of crisis.     

The Functional Morphology of the Recent Brachiopod Bouchardia rosea

Abstract The living terebratellid brachiopod Bouchardia rosea (Mawe), from the southeast Atlantic Ocean, has an unusual internal morphology; both valves are so heavily thickened posteriorly as almost to fill the space, leaving room only for the pedicle, its posterior adjuster muscles and the diductor muscles. These structures are here described in functional terms for the first time and, with the help of partial dissection of the soft tissues, the true nature of the musculature is revealed. Despite its unusual aspects, cardinalial structures of the dorsal valve can be interpreted in terms of those more commonly found in terebratellids. Copyright © 1996 The Royal Swedish Academy of Sciences. Published by Elsevier Science Ltd.     

Brachiopod Shell Proteins: Their Functions and Taxonomic Significance

The calcareous shell of the Brachiopoda is interspersed withorganic material, chiefly protein and polysaccharide. The aminoacid compositions of these proteins reflect their geneticallycoded biosynthesis and are phylogenetically and taxonomicallyinformative. The taxonomic scheme based on protein data agreeswith the scheme based on morphological and anatomical criteria.These findings indicate Crania occupies an anomolous position. Brachiopoda exhibit two main types of calcification, carbonateand phosphate. The hydroxyproline found in phosphatic inarticulateshell protein suggests an analogy with bone collagen, but theglycine content is too low to allow triple-helix formation. The number and nature of polypeptide chains making up the shellproteins have been determined by amino and carboxy end-groupanalysis as well as disc electrophoresis with SDS. In the nativestate the shell proteins are molecular aggregates and are dissolvedby 8 M urea, suggesting that the inter-chain links are largelyH–bonds. Articulate shell protein probably serves as a resilient cushioningbetween calcite fibers to protect against mechanical shock.This would be permitted by the amorphous flexible characterof the polypeptide chain. The shell proteins of the Inarticulataare different,their chitin-protein laminated shell is more sheet-likeand its structure requires less cushioning. Study of fossil protein can shed further light on shell proteinancestry and hence on brachiopod phylogeny.     

鸡生长分化因子GDF—8cDNA的克隆、表达及蛋白纯化

Growth and Differentiation Factor-8(GDF-8) is a new member of TGF-beta super-family. It has been shown that GDF-8 is specifically expressed in skeleton muscle in mouse and its function is to inhibit the growth of muscle cell, so it is named as Myostatin. Here, we amplified 3'half-length GDF-8 cDNA from chicken skeleton muscle by RT-PCR, and cloned it into the prokaryotic expression vector pTrcHisB, which was then transformed into E. coli Top10 cells. The recombinant 6 x His-GDF-8 fusion protein expressed in the Top10 cells was purified by Ni(+)-Affinity Chromatography for future study.     

鸡生长分化因子GDF-8 cDNA的克隆、表达及蛋白纯化

1997年John Hopkins大学的McPherron AC等[1]从小鼠骨骼肌cDNA文库中克隆得到1个新基因GDF-8(Growth andDifferential Factor-8),从蛋白结构来看,GDF-8因子具有TGF-β超家族的典型结构特征,其中包括分泌用的信号肽、蛋白酶水解加工位点及含9个半胱氨酸残基的高度保守的C端区域.进一步研究发现GDF-8主要在小鼠的骨骼肌中表达,并且GDF-8基因敲除鼠的骨骼肌是正常野生型小鼠的3倍以上2],这是继1982年Palmiter等将大鼠的生长激素基因转入小鼠体内产生"超级小鼠"之后的又一只"超级小鼠".     

Cell Wall Growth During Differentiation of Proteus Swarmers

This paper describes the process by which the cell wall of Proteus mirabilis, as measured by the presence of the O antigen, develops during the differentiation of swarmers from short cells on an agar surface. The sequence was followed by fluorescent-antibody staining, with both the direct and reverse methods. When the organisms were labeled with fluorescent antibody by the direct method, they showed a progressive diminution of the marker along the cell surface and some increase in the length of the bacteria. However, the label had become completely diluted out before typical swarmers developed. When the bacteria were exposed initially to unlabeled antibody by the reverse technique, and then incubated with fluorescent antibody, they showed a progressive increase both in the intensity of the label along their entire periphery and in cellular length, culminating in the formation of swarmers. It is concluded that in P. mirabilis, as in the few other gram-negative bacteria examined so far, cell wall synthesis takes place diffusely, i.e., by intercalation of new with old components along the length of the cell wall.     

Opposing Effects of Growth and Differentiation Factors in Cell-Fate Specification

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生长分化因子9基因的分子生物学

生长分化因子9是卵母细胞分泌的一种生长因子,它对卵泡的生长分化起着重要作用。本文介绍了生长分化因子9的结构、功能和调控,生长分化因子9基因的克隆及基因结构、发育性表达和作用、定位和多态性,并讨论了该基因与哺乳动物繁殖性能的关系。     

野生胭脂花(Primula maximowiczii)生长发育和花芽分化研究

以北京东灵山胭脂花自然分布地野生群体中2年生以上植株为研究对象,于2008～2010年连续3年观测了野生胭脂花的年生长发育进程,并采用石蜡切片法制片,通过普通光学显微镜和体视显微镜观察了胭脂花花芽分化和花序发育的过程,以探明野生胭脂花生长发育和花芽分化的规律,为人工栽培胭脂花提供依据。结果显示:(1)胭脂花的年生长发育进程可分为萌芽期、营养生长期、开花期、果实发育期、果熟期、花芽分化期和休眠期等7个阶段;5～9月为胭脂花的生长季,生长环境凉爽,日平均气温为5℃～20℃。(2)胭脂花花芽分化期为7月中下旬～9月上旬,历时约2个月,整个过程包括未分化期、花芽原基分化期、小花原基分化期和小花分化期;花序上的小花由外向内逐渐形成并发育,雌雄蕊的发育从8月中下旬开始到9月上中旬结束;花序发育完全的胭脂花植株进入休眠期,经过当年10月份至来年4月份的低温阶段翌年开花。胭脂花花芽分化进程和外部形态密切相关,可根据植株的外部形态特征快速判定花序发育状况。