Sponge: effect on the form of reef corals

The sponge, Mycale laevis, when encrusting the lower surfaces of flattened reef corals, induces marked peripheral folding of the host colonies. This relationship, though facultative, has advantages for both associates. The sponge has a continually enlarging substrate that is free from competitive sessile forms. The coral may benefit from an increased feeding efficiency as a result of water currents produced by the sponge and it is protected from invasion by boring forms, notably clionid sponges.     

Coral chronometers: seasonal growth bands in reef corals

Autoradiagraphs and x-radiographs have been made of vertical sections through the centers of reef corals from Eniwetok. Radioactivity bands in the coral structure are caused by strontium-90 and are related to specific series of nuclear tests, thus making possible calculation of long-term growth rates. These data indicate that the cyclic variations in radial density revealed by x-radiography are annual.     

Localized dispersal and recruitment in great barrier reef corals: the helix experiment

To examine the problem of how far coral larvae disperse from their natal reef, coral recruitment densities were experimentally determined at distances up to 5 kilometers from a small, relatively isolated platform reef, Helix Reef, on the central Great Barrier Reef for 7 months. High concentrations of recruits, accounting for up to 40 percent of all recruitment, were found downstream of the reef in areas of high water residence time, suggesting that near-field(proximal) circulation has a profound influence on dispersal and recruitment of coral larvae. Coral recruitment declined logarithmically with distance from the reef, decreasing by an order of magnitude at radial distances of only 600 to 1200 meters. On an ecological time scale, advective dispersal of semipassive marine larvae with relatively short planktonic lives(minimally days) may be extensive, but success of recruitment is highly limited. Through evolutionary time, sufficient dispersal occurs to ensure gene flow to reef tracts hundreds or possibly thousands of kilometers apart. In the short term, however, coral reefs appear to be primarily self-seeded with respect to coral larvae.     

Light control of growth form in colonial reef corals: computer simulation

Computer simulation with plotter output reveals the close interrelation between ambient light and the skeletal morphogenesis of the massive Caribbean reef coral Montastrea annularis. This technique illustrates a new quantitative approach to evaluating ecological growth responses of colonial organisms.     

Community structure of corals and reef fishes at multiple scales

Distributions of numerical abundance and resource use among species are fundamental aspects of community structure. Here we characterize these patterns for tropical reef fishes and corals across a 10,000-kilometer biodiversity gradient. Numerical abundance and resource-use distributions have similar shapes, but they emerge at markedly different scales. These results are consistent with a controversial null hypothesis regarding community structure, according to which abundance distributions arise from the interplay of multiple stochastic environmental and demographic factors. Our findings underscore the importance of robust conservation strategies that are appropriately scaled to the broad suite of environmental processes that help sustain biodiversity.     

Martian north pole summer temperatures: dirty water ice

Broadband thermal and reflectance observations of the martian north polar region in late summer yield temperatures for the residual polar cap near 205 K with albedos near 43 percent. The residual cap and several outlying smaller deposits are water ice with included dirt; there is no evidence for any permanent carbon dioxide polar cap.     

Decadal trends in the north atlantic oscillation: regional temperatures and precipitation

Greenland ice-core data have revealed large decadal climate variations over the North Atlantic that can be related to a major source of low-frequency variability, the North Atlantic Oscillation. Over the past decade, the Oscillation has remained in one extreme phase during the winters, contributing significantly to the recent wintertime warmth across Europe and to cold conditions in the northwest Atlantic. An evaluation of the atmospheric moisture budget reveals coherent large-scale changes since 1980 that are linked to recent dry conditions over southern Europe and the Mediterranean, whereas northern Europe and parts of Scandinavia have generally experienced wetter than normal conditions.     

低温胁迫对葡萄根系膜系统和可溶性糖及脯氨酸含量的影响

以新疆北部鲜食葡萄的5个抗寒力不同的主栽品种为试验材料,经不同低温(-1,-2,-3,-4,-5,-6,-7℃)胁迫10h后测定不同葡萄品种根系的细胞膜透性和可溶性糖含量及脯氨酸含量变化。结果表明,随着处理温度的降低,细胞膜透性明显增加,抗寒性较强的巨峰电解质渗出率变化幅度最小,抗寒性较弱的全球红电解质渗出率的变化幅度最大,其他3品种居中;可溶性糖含量先上升后下降,以黑大粒增加幅度大,全球红增加幅度小;脯氨酸含量总体呈下降趋势,黑大粒根系中的脯氨酸含量明显高于其它4个葡萄品种。     

回头岸礁区4 种造礁珊瑚中可培养细菌的多样性

采用稀释涂布平板法,分离三亚鹿回头岸礁区4种造礁珊瑚及其周围海水中的细菌,并基于16S r RNA基因序列进行了系统发育分析,从而探讨造礁珊瑚中可培养细菌的物种多样性。从澄黄滨珊瑚(Porites lutea)、鹿角珊瑚(Acropora sp.)、盔形珊瑚(Galaxea sp.)、扁脑珊瑚(Platygyra sp.)样品中分别分离获得细菌60、61、54、20株,从珊瑚周边海水中分离获得细菌31株。16S r RNA基因序列分析表明,珊瑚来源的细菌分布于放线菌门(Actinobacteria)、α-变形菌纲(Alphaproteobacteria)、γ-变形菌纲(Gammaproteobacteria)、厚壁菌门(Firmicutes)和拟杆菌门(Bacteroidetes)。在属级水平上对4种珊瑚及海水来源细菌群落组成分析,发现在4种珊瑚中均有分布的属有3个,为Brachybacterium、Microbacterium和Ruegeria,珊瑚来源细菌类群有一定差异。同时发现4种珊瑚来源细菌与海水来源细菌类群差异较大。在分离的菌株中,有7株菌与已有效描述的细菌物种典型菌株的全长16S r RNA基因相似性低于97%,代表着潜在新属或新种。试验结果表明,三亚鹿回头岸礁区珊瑚中存在较为丰富的细菌多样性,并潜藏较多的新物种资源。     

2009年自然低温下优质稻种质资源耐冷性初步鉴定评价

[目的]从供试水稻种质材料中筛选耐冷性强的优良种质,为水稻耐冷性研究和利用积累材料,为优质稻耐冷品种选育提供优良亲本.[方法]利用早春低温和晚稻寒露风自然低温条件,采用早播早植法及晚播晚植法,对458份优质稻种质资源材料分别进行发芽期、幼苗期和抽穗扬花期的耐冷性初步鉴定与评价.[结果]在458份优质稻种质资源材料中,发芽期、幼苗期、抽穗扬花期表现耐冷性极强和强的种质分别有21份、15和76份、5和80份,分别占鉴定份数的4.59%、3.28%和16.59%、1.48%和23.74%.不同种质在不同生育期耐冷性表现不完全一致,但发芽期耐冷性强的种质在幼苗期也表现较强的耐冷性.筛选出在自然低温条件下各生育期均表现强或极强耐冷性的优质稻种质6份,如TKM10、三粒寸、湘晚籼13号、恢968选、649/五大稻种//649///649、253/P117//253///253.[结论]利用自然低温条件,可初步区分不同生育期耐冷性强与弱的优质稻种质资源,其适合对大量稻种资源进行耐冷性筛选鉴定;筛选出的耐冷性极强或强的种质具有较好的应用价值.在不同生育期均表现强耐冷性的6份优质稻种质,可作为耐冷亲本材料在水稻的耐冷性研究及优质稻耐冷育种中加以利用.     

Preliminary identification and evaluation of high quality rice germplasm resources for cold tolerance under natural low temperatures during 2009

[目的]从供试水稻种质材料中筛选耐冷性强的优良种质,为水稻耐冷性研究和利用积累材料,为优质稻耐冷品种选育提供优良亲本.[方法]利用早春低温和晚稻寒露风自然低温条件,采用早播早植法及晚播晚植法,对458份优质稻种质资源材料分别进行发芽期、幼苗期和抽穗扬花期的耐冷性初步鉴定与评价.[结果]在458份优质稻种质资源材料中,发芽期、幼苗期、抽穗扬花期表现耐冷性极强和强的种质分别有21份、15和76份、5和80份,分别占鉴定份数的4.59％、3.28％和16.59％、1.48％和23.74％.不同种质在不同生育期耐冷性表现不完全一致,但发芽期耐冷性强的种质在幼苗期也表现较强的耐冷性.筛选出在自然低温条件下各生育期均表现强或极强耐冷性的优质稻种质6份,如TKM10、三粒寸、湘晚籼13号、恢968选、649/五大稻种//649///649、253/P117//253///253.[结论]利用自然低温条件,可初步区分不同生育期耐冷性强与弱的优质稻种质资源,其适合对大量稻种资源进行耐冷性筛选鉴定;筛选出的耐冷性极强或强的种质具有较好的应用价值.在不同生育期均表现强耐冷性的6份优质稻种质,可作为耐冷亲本材料在水稻的耐冷性研究及优质稻耐冷育种中加以利用.     

Understanding reactivity at very low temperatures: the reactions of oxygen atoms with alkenes

A remarkable number of reactions between neutral free radicals and neutral molecules have been shown to remain rapid down to temperatures as low as 20 kelvin. The rate coefficients generally increase as the temperature is lowered. We examined the reasons for this temperature dependence through a combined experimental and theoretical study of the reactions of O(3P) atoms with a range of alkenes. The factors that control the rate coefficients were shown to be rather subtle, but excellent agreement was obtained between the experimental results and microcanonical transition state theory calculations based on ab initio representations of the potential energy surfaces describing the interaction between the reactants.     

低温处理对黄花乌头抗逆性的影响

研究低温处理对黄花乌头抗逆性生理指标的影响,确定黄花乌头所能承受的低温时间.以未经处理、无病虫害黄花乌头植株顶端第5～8片完整的叶片为试验材料,分别进行2～5 ℃下0、1、2、3、4、5 d的低温处理,对其脯氨酸、丙二醛含量以及电导率进行测定.结果表明,低温处理时间不同,黄花乌头叶片的抗逆性生理指标存在明显差异.黄花乌头叶片的丙二醛含量和电导率均随低温处理时间的延长而逐步上升;低温处理1 d后,叶片脯氨酸含量达到最大值,低温处理1～5 d脯氨酸含量逐渐减少.表明黄花乌头所能承受的低温处理时间不超过4 d,低温处理1 d时抗逆性最强.     

不同温度下4种常见孔雀鱼的盐度耐受极限试验

为通过调节养殖水体的盐度进行孔雀鱼Poecilia reticulate疾病防控与治疗,对豹点、象牙白、红扇、冰蓝等4个品系的孔雀鱼进行了盐度耐受极限试验,分别在盐度为0、20、28环境下观察孔雀鱼的活动状态并计算死亡率,同时探究不同温度(16、22、28℃)下,孔雀鱼的盐度耐受极限是否发生变化。结果表明:高盐(盐度为28)环境下,孔雀鱼发生半致死的时间更短,温度与盐度对豹点与红扇孔雀鱼的致死存在显著的交互作用(P<0.05);低盐(盐度为20)环境下,升高水温能够显著提高这两种孔雀鱼的盐度耐受极限,而高盐(盐度为28)环境下,升高水温能够显著降低这两种鱼的盐度耐受极限(P<0.05),降低水温能够显著提高这两种鱼的盐度耐受极限(P<0.05)。研究表明,温度对孔雀鱼的耐盐极限有一定影响。     

不同温度下4种常见孔雀鱼的盐度耐受极限试验

为通过调节养殖水体的盐度进行孔雀鱼Poecilia reticulate疾病防控与治疗,对豹点、象牙白、红扇、冰蓝等4个品系的孔雀鱼进行了盐度耐受极限试验,分别在盐度为0、20、28环境下观察孔雀鱼的活动状态并计算死亡率,同时探究不同温度(16、22、28℃)下,孔雀鱼的盐度耐受极限是否发生变化。结果表明:高盐(盐度为28)环境下,孔雀鱼发生半致死的时间更短,温度与盐度对豹点与红扇孔雀鱼的致死存在显著的交互作用(P0.05);低盐(盐度为20)环境下,升高水温能够显著提高这两种孔雀鱼的盐度耐受极限,而高盐(盐度为28)环境下,升高水温能够显著降低这两种鱼的盐度耐受极限(P0.05),降低水温能够显著提高这两种鱼的盐度耐受极限(P0.05)。研究表明,温度对孔雀鱼的耐盐极限有一定影响。     

不同氮水平对棉苗抗低温的影响

在22～28℃条件下,分别用0.00,1.00,2.00,3.00和4.00 g·L-1尿素水溶液浇灌培养棉苗至3叶1心,然后在人工气候箱内进行(15±1)℃/(5±1)℃(昼/夜)低温处理3d,研究了棉苗生长恢复及生理变化情况.结果表明,无氮处理棉苗抗低温能力差,受低温胁迫伤害严重,表现可溶性糖含量低,SOD和CAT...     

番茄种质芽期耐低温性评价及耐低温指标筛选

为筛选种子芽期耐低温的番茄种质资源及耐低温性评价的关键指标,以25份番茄种质资源为材料,分别测定15和25 ℃下其发芽率、发芽势、发芽指数、萌发指数、抗寒指数、发芽受损率、胚根长度、活力指数、鲜重和干重共10个指标,比较上述指标的性状相对值并对其进行相关性分析、主成分分析和隶属函数分析,对番茄种质资源芽期耐低温性进行综合评价;利用综合评价值（D）,采用组间联接法和欧氏距离对种质资源进行聚类分析;采用逐步回归分析法建立番茄种质资源芽期耐低温性最优回归方程,并筛选耐低温性评价的关键指标。结果表明：材料1（20cl0347-0）的D最大,为0.984,其芽期耐低温性最强;材料23（20cl2147-0）的D最小,为0.075,其耐低温性最弱。25份番茄种质资源材料分为5类,其中高度耐低温型种质为20cl0347-0,耐低温型种质5份、中度耐低温型10份、敏感型6份和高度敏感型3份。番茄种质资源芽期耐低温性最优回归方程为D = 0.411 + 0.027X₂ + 0.128X₃ + 0.053X₆ + 0.038X₈ + 0.035X₉,筛选出耐低温性评价的关键指标依次为：相对发芽势、相对发芽指数、相对胚根长度、相对鲜重及相对干重,可用于番茄种质资源芽期耐低温性高效评价。     

Temperature acclimation: improved sustained swimming performance in carp at low temperatures

At low temperatures, the reduction in mechanical power output of the aerobic muscle forces cold-blooded animals, such as carp, to recruit their rapidly fatiguing anaerobic fibers at relatively slow swimming speeds. Previous experimental data have suggested that changes in the biochemistry and morphology of the aerobic muscle during cold acclimation might increase its output of mechanical power. The present experiments show that, because of these changes, carp can swim faster at low temperature using only their aerobic muscle, which results in an increase in their sustainable swimming speed. By modifying their musculature, cold-blooded animals can achieve some independence from the effects of seasonal changes in environmental temperature.