The Calyptogena magnifica chemoautotrophic symbiont genome

Chemoautotrophic endosymbionts are the metabolic cornerstone of hydrothermal vent communities, providing invertebrate hosts with nearly all of their nutrition. The Calyptogena magnifica (Bivalvia: Vesicomyidae) symbiont, Candidatus Ruthia magnifica, is the first intracellular sulfur-oxidizing endosymbiont to have its genome sequenced, revealing a suite of metabolic capabilities. The genome encodes major chemoautotrophic pathways as well as pathways for biosynthesis of vitamins, cofactors, and all 20 amino acids required by the clam.     

Thermal Vent Clam (Calyptogena magnifica) Hemoglobin

A heterodont bivalve mollusk Calyptogena magnifica, from the East Pacific Rise and the Galápagos Rift hydrothermal vent areas, contains abundant hemoglobin in circulating erythrocytes. No other known heterodont clam contains a circulating intracellular hemoglobin. The hemoglobin is tetrameric and has a relatively high oxygen affinity, which varies only slightly between 2 degrees and 10 degrees C. The presence of hemoglobin in the clam may facilitate the transport of oxygen to be used in chemoautotrophic hydrogen sulfide metabolism.     

Analysis of hydrothermal vent-associated symbionts by ribosomal RNA sequences

Ribosomal RNA (rRNA) sequences were used to establish the phylogenetic affiliations of symbioses in which prokaryotes appear to confer sulfur-based chemoautotrophy on their invertebrate hosts. Two submarine hydrothermal vent animals, the vestimentiferan tube worm Riftia pachyptila and the clam Calyptogena magnifica, and a tidal-flat bivalve, Solemya velum, were inspected. 5S rRNA's were extracted from symbiont-bearing tissues, separated into unique forms, and their nucleotide sequences determined and related to other 5S rRNA's in a phylogenetic tree analysis. The prokaryotic symbionts are related to one another and affiliated with the same narrow phylogenetic grouping as Escherichia coli and Pseudomonas aeruginosa. The sequence comparisons suggest that Riftia is more closely related to the bivalves than their current taxonomic status would suggest.     

Strontium Uptake in Shell Aragonite from the Freshwater Gastropod Limnaea stagnalis

Shell aragonite from 96 specimens of the freshwater gastropod Limnaea stagnalis grown in laboratory tanks at different temperatures in water with variable strontium/calcium ratios have been analyzed for its strontium content in order to evaluate the mechanisms of strontium uptake in molluskan aragonite. Within the limits defined by natural freshwater environments, the strontium/calcium ratio in the aragonite was found to be linearly related to the strontium/calcium ratio in the water. A distribution coefficient k(A)(Sr) = 0.237 +/- 0.029, unaffected by variations in temperature and growth rate, has been found. This finding substantiates the existence of a strontium-discriminating effect in aragonite precipitated by mollusks as compared to the case for nonbiogenic aragonite which contains about five times as much strontium when precipitated under the same conditions.     

Imaging powders with the atomic force microscope: from biominerals to commercial materials

Atomically resolved images of pressed powder samples have been obtained with the atomic force microscope (AFM). The technique was successful in resolving the particle, domain, and atomic structure of pismo clam (Tivela stultorum) and sea urchin (Strongylocentrotus purpuratus) shells and of commercially available calcium carbonate (CaCO(3)) and strontium carbonate (SrCO(3)) powders. Grinding and subsequent pressing of the shells did not destroy the microstructure of these materials. The atomic-resolution imaging capabilities of AFM can be applied to polycrystalline samples by means of pressing powders with a grain size as small as 50 micrometers. These results illustrate that the AFM is a promising tool for material science and the study of biomineralization.     

Biological Controls on Coral Sr/Ca and dgr18O Reconstructions of Sea Surface Temperatures

Coral strontium/calcium ratios have been used to infer that the tropical sea surface temperature (SST) cooled by as much as 6 degrees C during the last glacial maximum. In contrast, little or no change has been inferred from other marine-based proxy records. Experimental studies of the effect of growth rate and the magnitude of intraspecific differences indicate that biological controls on coral skeletal strontium/calcium uptake have been underestimated. These results call into question the reliability of strontium/calcium-based SST reconstructions.     

Gas-phase inorganic chemistry: monovalent derivatives of calcium and strontium

The chemistry and spectroscopy of monovalent derivatives of calcium and strontium are described. Laser-driven chemical reactions of calcium and strontium vapors with a variety of small molecules have provided many new free radicals. In general, these species are analogous to the stable molecules obtained in traditional inorganic or organometallic chemistry, but some new families of molecules have been discovered.     

Strontium incorporation into dental enamel

Rats were raised on diets either rich or poor in strontium. Powder x-ray diffraction patterns suggest that isomorphous substitution of strontium for calcium occurs in the apatite of tooth enamel, and that strontium may form Sr(6)H(3)(PO(4)) * 2H(2)O, a compound hitherto unreported in biologic systems.     

Growth rate of a vesicomyid clam from the galapagos spreading center

The shell of a 19-centimeter-long vesicomyid clam, collected live at the Galápagos spreading center hydrothermal field, was sampled along growth lines and analyzed for members of the (238)U and (232)Th decay series. The growth rate, determined from the (210)Po/(210)Pb and (228)Th/(228)Ra couples, is about 4 centimeters per year along the axis of maximum growth, which is 12 centimeters long. This yields an age of 3 to 4 years for this clam.     

高盐对缢蛏生长存活、Na+/K+-ATPase活性及能量代谢相关指标的影响

以缢蛏（Sinonovacula constricta）为研究对象,设置养殖周期为60 d的对照组（20）和高盐组（30）比较实验,分别在0、10、30和60 d进行取样,检测高盐对缢蛏生长存活、鳃组织Na+/K+-ATPase（NKA）活性及肝胰腺和血清能量代谢相关指标的影响。结果表明,高盐组缢蛏在30~60 d的养殖时间段内存活率为45.1%±2.9%,壳长、壳宽、壳高和体质量特定生长率分别为0.15%/d、0.17%/d、0.13%/d和0.61%/d,均显著低于对照组。各时间点高盐组NKA活性均显著低于对照组。10和60 d时对照组缢蛏肝胰腺己糖激酶（HK）活性显著高于高盐组,血清中葡萄糖（GLU）含量、乳酸（LA）含量和乳酸脱氢酶（LDH）活性也显著高于高盐组,高盐组缢蛏无氧代谢水平低于对照组。30 d时高盐组血清中GLU含量、LA含量和LDH活性显著高于对照组,高盐组缢蛏无氧代谢水平高于对照组。0、10和30 d时高盐组肝胰腺琥珀酸脱氢酶（SDH）活性显著高于对照组,高盐胁迫下缢蛏需氧代谢水平上升。研究表明：长期高盐养殖下,缢蛏仍能保持一定的存活率和生长速度;高盐影响了缢蛏的渗透调节和能量代谢,渗透调节增加了其能量消耗。本研究为进一步培育缢蛏耐高盐新品系提供了参考资料。     

增施钾肥对国光苹果生长发育及营养状况的影响

本试验以20年生‘国光/八楞海棠’苹果为试材,研究了土壤增施钾肥(氯化钾)对果树生长发育和营养状况等方面产生的影响。     

Strontium-calcium thermometry in coral skeletons

The strontium to calcium ratio of skeletal aragonite in three genera of reef-building corals varies as a simple function of temperature and the strontium to calcium ratio of the incubation water. The strontiumlcalcium distribution coefficients of coral aragonite apparently differ from the corresponding coefficient of inorganically precipitated aragonite. With some care, coral skeletons can be used as recording thermometers.     

Strontium induced rickets: metabolic basis

Dietary strontium inhibits both the synthesis of 1,25-dihydroxycholecalciferol and intestinal calcium absorption in vitamin D(3)-repleted chicks. 1,25-Dihydroxycholecalciferol restores calcium absorption to normal, while 25-hydroxycholecalciferol is without effect in the strontium-fed chick. It is suggested that strontium induces rickets by blocking the biosynthesis of 1,25-dihydroxycholecalciferol, the metabolically active form of vitamin D in the intestine.     

Strontium uptake in rats on alginate-supplemented diet

Rats were fed a basic diet supplemented with sodium alginate and with tracer amounts of strontium-85 and calcium-45. Absorption of strontium was always inhibited by the alginate to a greater extent than absorption of calcium. Discrimination against strontium was greatest in alginate containing a high proportion of guluronic acid.     

金龟子幼虫种类研究Ⅳ

对华美花金龟（Ｃｅｔｏｎｉａ ｍａｇｎｉｆｉｃａ Ｂａｌｌｉｏｎ）、疏纹星花金龟「Ｐｏｔｏｓｉａ ｃａｔｈａｉｃａ （Ｂａｔｅｓ）」、蓝边矛丽金龟（Ｃａｌｌｉｓｔｅｔｈｕｓ ｐｌａｇｉｉｃｏｌｌｉｓ Ｆａｉｒｍａｉｒｅ）、茸喙丽金龟（Ａｄｏｒｅｔｕｓ ｐｕｂｅｒｕｌｕｓ Ｍｏｔｓｅｈｕｌｓｋｙ）共４种金龟子幼虫首次进行了形态描述,并绘制了种的形态特征图。     

文蛤池塘养殖密度调控效果比较

应用种群生长与密度关系的规律,对文蛤池塘养殖密度、产量和产品规格的关系进行了比较试验,依据密度制约方程,当养殖密度随个体增长而增大至一定程度并抑制生长速度时,分塘疏养。结果揭示在单位面积毛产量、净产量、总产值、净利润、产量/投放量比等方面,以放养密度8 840粒/m2(680 g/m2)组最好。分塘疏养以放养密度1 253粒/m2(1 724 g/m2)组为好。密度低的池塘内文蛤平均壳长、壳高、壳宽,增重量和增长率均比高密度组大。对文蛤池塘养殖产量、产品规格和产值进行比较分析,对养殖密度调控技术进行了探讨。     

文蛤池塘养殖密度调控效果比较

应用种群生长与密度关系的规律,对文蛤池塘养殖密度、产量和产品规格的关系进行了比较试验,依据密度制约方程,当养殖密度随个体增长而增大至一定程度并抑制生长速度时,分塘疏养。结果揭示在单位面积毛产量、净产量、总产值、净利润、产量/投放量比等方面,以放养密度8 840粒/m2(680 g/m2)组最好。分塘疏养以放养密度1 253粒/m2(1 724 g/m2)组为好。密度低的池塘内文蛤平均壳长、壳高、壳宽,增重量和增长率均比高密度组大。对文蛤池塘养殖产量、产品规格和产值进行比较分析,对养殖密度调控技术进行了探讨。     

Hydrothermal Vent Clam and Tube Worm 13C/12C: Further Evidence of Nonphotosynthetic Food Sources

The stable carbon isotope ratios in clam mantle tissues taken from both Galápagos and 21 degrees N hydrothermal vent sites were similar to the unusually low ratios of carbon-13 to carbon-12 previously reported for a Galápagos hydrothermal vent mussel. In marked contrast to these bivalves, vestimentiferan worm tissues from a Galápagos vent had isotope ratios that were higher than those of open ocean biota. These observations suggest that more than one nonpelagic and nonphotosynthetic carbon fixation pathway is of nutritional importance to vent animals, and that at least one of these pathways is common to two geographically separated vent sites.     

4种壳色菲律宾蛤仔在低氧胁迫下的耐受能力比较研究

菲律宾蛤仔Ruditapes philippinarum对环境中溶氧剧烈的波动有较强的适应能力,为了探讨抗氧化酶和热休克蛋白在蛤蛤恣仔的低氧耐受过程中发挥的作用,以对低氧具有不同耐受能力的4种壳色蛤仔(野生蛤仔、斑马蛤、白蛤、白斑马蛤)为研究对象,比较了在1 mg/L的低氧胁迫条件下其抗氧化酶家族基因成员(TPx、CAT、Mn-SOD、Cu/Zn-SOD)和热休克蛋白家族基因成员(HSP40、HSP75、Vps HSP-1、Vps HSP-2)的表达量变化情况。结果表明:在鳃组织中,野生蛤仔的抗氧化酶基因表现出先升高后恢复的趋势,在胁迫后6 h时表达量达到最高值(P0.05),其他3种壳色蛤仔的抗氧化酶基因表现出先降低后恢复的趋势,在胁迫后6 h时表达量达到最低值(P0.05),斑马蛤的TPx基因表达量在胁迫的各个时间点均显著高于其他3种壳色蛤仔(P0.05);在外套膜组织中,4种壳色蛤仔中的抗氧化酶基因均表现出先升高后恢复的趋势,白蛤TPx基因和白斑马蛤CAT基因表达量在胁迫的各个时间点均显著高于其他3种壳色蛤仔(P0.05);在鳃组织中,斑马蛤和白斑马蛤中热休克蛋白家族基因成员表现出先降低后升高再降低的趋势,分别在24 h、6 h时达到最低值(P0.05),野生蛤仔和白蛤中热休克蛋白家族基因成员表现出先升高后降低的趋势,在胁迫6 h时,白蛤热休克蛋白家族基因成员表达量达到最高值(P0.05),胁迫12 h时,野生蛤仔达到最高值(P0.05);在外套膜组织中,白斑马蛤中热休克蛋白家族基因成员表达量出现先降低后升高的趋势,在胁迫6 h时达到最低值(P0.05),而其他3个壳色蛤仔中热休克蛋白家族基因表达量表现出先升高后降低的趋势,在胁迫6 h时野生蛤仔和白蛤热休克蛋白家族基因成员表达量达到最大值(P0.05),12 h时斑马蛤达到最大值(P0.05),且白蛤HSP40基因表达量在胁迫的各个时间点均显著高于其他3种壳色蛤仔(P0.05)。研究表明,斑马蛤和白蛤的TPx基因可能参与其体内黑色素合成的过程,初步证实了不同壳色蛤仔参与色素合成过程的相关基因在其对低氧的耐受过程中能够发挥重要作用。     

高等植物果聚糖合成途径、相关基因和功能的研究进展

以瓷玫瑰为材料,对其花枝生长发育及观赏特点进行观察和了解,在此基础上进行切花保鲜处理和保鲜水分生理的探讨。结果表明,瓷玫瑰花枝整个生长发育期长达90多天,可划分为花蕾期、初开期、盛开期、凋萎期4个阶段。可将切花瓶插过程的萎蔫程度划分为4个等级。蔗糖等4种保鲜剂均有延长瓶插寿命的效果,而以2.0%蔗糖的效果最好。蔗糖和柠檬酸对保鲜起着非常重要的作用,含较高浓度蔗糖和柠檬酸的处理C瓶插寿命达到11d。