莼菜休眠芽解除休眠及生根的研究

莼菜为世界著名珍稀水生蔬菜,具有很高的食用和药用价值。已有研究显示,可通过冬芽实现莼菜复壮,找出休眠解除的最佳方法是复壮的基本前提。本实验以莼菜冬季型休眠芽（冬芽）为实验材料,通过光照、温度等处理探求莼菜冬芽的休眠解除方法。莼菜冬芽生根率随着光照强度的增加,其生根率由全黑暗0%显著增长至（16.0±1.3）%;温度和处理时间对莼菜冬芽生根率、根长、生根根数和含水量有显著性影响。其中,35 °C水浴处理6 h后各项指标均到达较大值,上述指标分别为（96.1±2.8）%、（7.2±0.2） cm、74.5±6.0和（83.6±0.3）%;40 °C（6 h）、45 °C（1、3和6 h）和50 °C（10、20和30 min）水浴处理后莼菜冬芽绝大部分失绿变黄;随着培养时间的延长,其冬芽全部腐烂。光照能够促进莼菜冬芽生根;土培生根效果较为显著;适度水浴加热处理能有效解除莼菜冬芽的休眠,35 °C水浴处理6 h为最佳处理方案。     

南极产低温脂肪酶菌株Psychrobacter sp. 7195 的 选育、发酵条件及酶学性质研究

从南极普里兹湾深海沉积物中筛选到一株产低温脂肪酶的菌株7195,细菌学形态鉴定及16S rDNA序列分析表明该菌株属于嗜冷杆菌属 (Psychrobacter). 生长特性研究表明该菌株属于耐冷菌,其最适生长温度范围为5～15°C, 7195菌株能利用多种碳、氮源产酶.粗酶液经硫酸铵盐析、DEAE cellulose-52 柱层析进行初步分离纯化后进行酶学性质的研究. 该菌株所分泌的脂肪酶最适作用温度为30°C,最适pH值为9.0,对热敏感,60°C热处理10min剩余酶活为30%,是典型的低温酶. Ca2+、Mn2+、Cu2+对该酶有较为明显的激活作用,而Co2+、Zn2+、Hg2+、Rb2+、Cd2+、Fe3+、EDTA则能抑制酶活,此外该脂肪酶能在高浓度的SDS、CHAPS、Triton X-100、Tween 80、Tween20等变性剂中表现出较好的稳定性.     

低温沼气发酵优良菌系筛选及优势菌群分析

【目的】为获得低温沼气发酵高效菌系, 从张家口、承德和邯郸地区采集低温产气良好的沼气池中沼泥样品12份。【方法】以沼泥为接种源进行16 °C?5 °C阶段降温模拟沼气发酵试验, 对处理组HL2、ZG2、CW1及其相应的接种源HLA、ZGB、CWB进行DGGE分析。【结果】ZG2处理组模拟沼气发酵综合性能最优, 与其他处理组呈显著性差异; DGGE图谱显示, 被检测样品中古菌种属多样性丰富, 但图谱中代表优势种属条带的位置存在较大差异。通过16S rDNA克隆及测序分析, 样品中主要优势菌属为甲烷八叠球菌属、甲烷鬃毛菌属和甲烷粒菌属。【结论】DGGE图谱中代表甲烷八叠球菌属的条带是样品ZG2和ZGB中唯一重复出现的条带, 且未作为优势条带出现在其他样品中, 推测甲烷八叠球菌属与低温产沼气有密切相关性。     

好氧反硝化菌的筛选及其脱氮除磷性质的研究

利用富集培养基, 从用生活污水驯化后的活性污泥中筛选得到一株具有好氧反硝化兼具除磷功能的细菌。通过形态学及生理生化指标鉴定其为假单胞菌属。利用此好氧反硝化菌处理模拟废水及生活废水, 通过监测总氮、无机磷及CODcr变化确定在C/N摩尔比为3:1、接种量为10%、pH 6.8、30°C条件下处理2 d, 该菌株脱氮、除磷及去除有机物的效果最佳, 活性污泥经此好氧反硝化菌强化后, 对生活废水的处理能力得到明显提升。     

四个类群海洋蛭弧菌类生物生长特性的比较

研究了噬菌弧菌科(Bacteriovoracaceae) 4个类群共12株海洋蛭弧菌类生物(Bdellovibrio- and-like organisms, BALOs)的生长温度和盐度范围及其对6种常见对虾病原弧菌的裂解能力, 并通过透射电镜分析了其中4个代表菌株的形态特征。结果表明, 同一群或亚群内菌株的生长温度或盐度相同, 即类群IV、VI、IX、X菌株的生长温度范围分别为20°C~35°C、15°C~35°C、15°C~ 40°C和10°C~40°C, 最适生长温度为30°C或35°C; 生长盐度范围分别为5‰~40‰、2.5‰~30‰、5‰~60‰和5‰~60‰, 最适生长盐度分别为10‰、5‰、20‰和20‰。测试的6种弧菌中有3种可被全部BALOs裂解, 而其它弧菌仅被部分BALOs裂解, 但即使同一类群菌株, 对某些弧菌也表现不同的裂解能力。形态上, 4株不同类群BALOs均呈典型的弧状细胞, 具极生单鞭毛。     

不同温度对七种外来杂草生理指标的影响及其适应意义

加拿大一枝黄花(Solidagocanadensis)、小飞蓬(Conyzacanadensis)、野塘蒿(Conyzabonarinsis)、钻形紫菀(Astersublatus)、一年蓬(Erigeronannuus)、马缨丹(Lantanacamara)和金鸡菊(Coreopsislanceolata)是我国东南地区有分布的7种外来杂草。测定了38°C、25°C和5°C处理下它们的可溶性糖、脯氨酸、丙二醛含量和过氧化物酶活性。结果表明,7种杂草对高温的耐受能力,由大到小分别为野塘蒿、小飞蓬、钻形紫菀、加拿大一枝黄花、马缨丹、一年蓬和金鸡菊,对低温的耐受能力,由大到小则分别为野塘蒿、小飞蓬、马缨丹、一年蓬、钻形紫菀、加拿大一枝黄花和金鸡菊。分析了四种生理指标变化的生态适应意义。     

一株高效苯酚降解菌的选育及降酚性能研究

从一绝缘材料厂的污水中分离得到一株可高效降解苯酚的菌株JY01, 该菌株的形态和理化特征与Bacillus基本相同, 其16S rDNA序列与Bacillus simplex (AM9216370)的相似性为99.01%。在接种量为2%的条件下, 该菌在pH为6.0~9.0和温度为18°C~36°C的范围内保持对苯酚良好的降解能力; 30 h内, 当苯酚浓度为1100 mg/L和1300 mg/L时, 其降解率分别为99.16%和74.76%。这将为进一步采用生物法处理含酚废水提供了可靠的控制条件。     

嗜热链球菌CGMCC 1.1864所产的一种新型细菌素ST9

本文利用琼脂扩散法测定嗜热链球菌(Streptocccus thermophilus) CGMCC 1.1864发酵上清液的抑菌效果, 结果表明此菌能够产生抑菌物质, 且在排除有机酸和过氧化氢的影响后上清液不但能抑制革兰氏阳性菌, 对革兰氏阴性菌也有抑制能力。此抑菌物质具有热稳定性, 于100°C处理 2 h及121°C处理20 min仍保留抑菌活性, 但若将其在100°C处理2 h的上清液立即置于?20°C保存, 其抑菌活性有较大损失。常温下(37°C), 该抑菌物质在pH 2.0?9.0范围内有很好的稳定性。发酵上清液经各种蛋白酶及?-淀粉酶处理后抑菌活性完全消失, 而对过氧化氢酶不敏感, 表明此抑菌物质为多肽, 属于细菌素, 本文初步将其命名为嗜热链球菌素ST9。由于ST9对其产生菌具有吸附作用, 选择pH吸附释放法对该嗜热链球菌素进行粗提, 然后经SephadexG-25凝胶层析柱除去杂蛋白, 最后冷冻干燥得纯品。通过Tricine-SDS-PAGE分析得到其分子量约为5.0 kD。     

国人跟骨结节关节角的测量计算

本文根据三角形有关原理,用直脚规测量计算的方法,测量计算了282块(男164;女118)国人成年跟骨的结节关节角。男性左右侧平均数分别为27.53°±0.91°和27.55°±0.87°,女性左右侧平均数分别为32.22°±1.46°和34.70°±1.25°。经统计学处理,侧别间均无差异,但性差非常显著(P<0.01)。此方法较应用测角仪简单易行。     

低温污水生物处理技术研究现状与展望

我国绝大多数地区冬季污水处理能力降低,处理成本增加,进而影响周边环境,危害人类健康。总结了近年来国内外学者对低温污水生物处理技术的研究成果,以不同形态污泥(絮状污泥、厌氧颗粒污泥和好氧颗粒污泥)为出发点展开分析,通过对不同形态污泥的优缺点的对比,展望了低温污水生物处理技术的发展前景。     

Oil pollution in the North Sea—a microbiological point of view

In this study we determined oil degradation rates in the North Sea under most natural conditions. We used the heavy fuel oil, Bunker C, the major oil pollutant of the North Sea, as the model oil. Experiments were conducted in closed systems with water sampled during winter and repeated under identical conditions with water collected during summer. No nitrogen or phosphorous was added and conditions were chosen such that neither oxygen nor nutrients, present in the water, would become limiting during the experiments. We detected a fourfold increased degradation rate for water samples taken in summer (18°C water temperature) as compared to water sampled in winter (4°C water temperature). Under the assumption that biodegradation of oil can be regarded as a Michaelis-Menten type kinetic reaction, the kinectic constants V_max and K_M were determined for oil biodegradation at 4°C and 18°C. At both temperatures K_M was about 40 ppm, whereas V_max was 3–4 times higher at 18°C. From both V_max and the results of fermentation studies, we determined the maximum rates of Bunker C oil degradation in the North Sea as ∼20 g m⁻³a⁻¹ at 4°C in winter and 60–80 g m⁻³a⁻¹ at 18°C in summer. Furthermore, while over 25% of the oil was degraded within 6 weeks in summer, only 6.6% of the oil was degraded in winter. A higher incubation temperature in winter (18°C) increased both the rate and the percentage of oil degraded, but degradation did not reach the level obtained during the summer. While these data reflect the oxidation only of the hydrocarbons, we conducted experiments directly in the open sea to determine the contribution of abiotic factors to oil removal. Approximately 42% of the oil was lost within 6 weeks under these conditions in summer and 65% in winter. However, GC-MS analysis of the recovered oil showed no significant change in the alkane pattern that would indicate enhanced degradation. Thus, mainly abiotic factors such as erosion and dispersion rather than degradation were responsible for enhanced oil removal. Especially the high loss during winter can be attributed to frequent storms resulting in greater dispersion. In conclusion, the higher oil degrading potential of the microbial population in the North Sea was represented by a four times faster oil degradation during the summer. In-situ experiments showed that abiotic factors can have an equal (summer) or even higher (winter) impact on oil removal.     

Low-temperature tolerance of juvenile tarpon <Emphasis Type="Italic">Megalops atlanticus</Emphasis>

The tarpon Megalops atlanticus is a tropical to subtropical species whose pole-ward distribution is thought to be limited by low water temperatures. In the western north Atlantic Ocean juvenile tarpon occur in estuaries of the South Atlantic Bight (SAB) north of Florida near the northern limit of its distribution, but it is currently unknown whether these individuals can survive winter, grow to maturity, and contribute to the adult population. As a first step to determine whether juvenile tarpon can survive winter conditions in the SAB, we conducted laboratory experiments to estimate minimum lethal temperatures of tarpon exposed to 1) ambient fluctuating winter water conditions and 2) a constant rate of temperature decline. Juvenile tarpon exposed to ambient winter water conditions had a mean ± standard deviation (SD) minimum lethal temperature of 13.7 ± 3.4 °C. When exposed to a constant rate of temperature decline (2 °C day^?1), mean ± SD minimum lethal temperature (9.2 ± 0.8 °C) was lower than when tarpon were exposed to ambient fluctuating conditions. A combination of our results with all published data on the cold tolerance of juvenile tarpon resulted in an overall mean ± SD minimum lethal temperature of 12.0 ± 2.8 °C. Based on available long-term temperature records from SAB estuaries, overwinter survival of juvenile tarpon is unlikely in most aquatic habitats (e.g., tidal creeks, flats, open water). Similar to other estuarine transient fishes, juvenile tarpon likely exploit seasonably favorable nursery habitats and then migrate to other locations to overwinter.     

Biological control of giant salvinia (Salvinia molesta) in a temperate region: cold tolerance and low temperature oviposition of Cyrtobagous salviniae

Success of Cyrtobagous salviniae Calder & Sands (Coleoptera: Curculionidae) for biological control of Salvinia molesta D. S. Mitchell in temperate regions has been less reliable than in tropical and subtropical regions and this difference is presumed to be due to greater winter mortality. We measured the cold tolerance of C. salviniae by comparing chill coma recovery time and survival of adults after exposure to freezing conditions among four geographic populations collected from Florida, Louisiana, Texas and Australia. Effects of winter temperature acclimation on low temperature oviposition also were determined. The Australian population was more cold tolerant than the three US populations. No oviposition by C. salviniae was observed at a water temperature of 17 °C and the oviposition rate at 19 °C was less than at 21, 23 and 25 °C. We suggest that introduction of cold tolerant strains of C. salviniae could increase its effectiveness in temperate regions of the US.     

SEASONAL DIFFERENCES IN THE TEMPERATURE RANGES OF GROWTH OF VIRGINIA ALGAE1

One hundred and fifteen clonal, unialgal strains were isolated and tested for their ability to grow over a range of temperatures from 2 to 40° C. Responses of 63 strains isolated from habitats that were 6° C when sampled and 52 strains isolated from habitats that were 20° C when sampled showed trends toward increasing adaptation to cold or warm temperatures commensurate with their seasonal in situ temperatures. Based on temperature-growth responses alone, 24% of the plankton isolates and 17% of the periphyton isolates could be perennial within the natural habitats. At 5° C, 56% of the warm water plankton isolates and 48% of the warm water periphyton isolates were incapable of growth and, therefore, probably could not be important components of the winter algal community. Likewise at 25° C, 25% of the cold water plankton isolates and 13% of the cold water periphyton isolates were incapable of growth. Thus, temperature alone probably is an important variable regulating seasonal changes in algal community structure. Pollution of these habitats by a thermal enrichment averaging + 5° C year-round could effect a pronounced change in algal species composition because many more taxa could be perennial and more taxa would be incapable of growth during naturally warm periods.     

Salicylic acid-induced antioxidant protection against low temperature in cold-hardy winter wheat

“Dongnongdongmai 1” is a cultivated winter wheat which can endure cold temperature as low as ?30 °C with a reviving rate of 85 %. We aimed to explore the involvement of antioxidant protection system in salicylic acid (SA)-enhanced cold resistance of winter wheat. Seedlings were prayed with 0.1 mM SA at three-leaf stage, followed by cold acclimation at tillering stage (4 °C for 5 days) prior to cold treatment at 4, 0, ?10 or ?20 °C for 2 days. Under low temperature, the relative electrical conductivity (REC) of rhizomes and H₂O₂ content in rhizomes were lower compared with leaves, while in the reactive oxygen species (ROS) removal system, only the POD activity was higher. Foliar spray with SA significantly inhibited the cold-increased REC of rhizomes at ?20 °C and REC of leaves at ?10 and ?20 °C. In addition, application of SA prior to ?10 or ?20 °C treatment suppressed the increase in H₂O₂ content both in rhizomes and leaves. SA enhanced the activities of SOD, POD, and CAT in wheat following low-temperature treatment, especially at ?10 and ?20 °C. In addition, spray with SA resulted in 1.1-to-4.9-fold enhanced activities of the key enzymes in AsA–GSH cycle, including APX, DHAR, and MDHAR. Our results suggested that SA could improve the resistance of winter wheat against extreme low temperature by enhancing the activities of antioxidases to eliminate ROS and maintain the redox homeostasis. In addition, the less damage to rhizomes in comparison with leaves may be attributed to enhanced POD activity.     

Some like it cold: Temperature‐dependent habitat selection by narwhals

The narwhal (Monodon monoceros) is a high‐Arctic species inhabiting areas that are experiencing increases in sea temperatures, which together with reduction in sea ice are expected to modify the niches of several Arctic marine apex predators. The Scoresby Sound fjord complex in East Greenland is the summer residence for an isolated population of narwhals. The movements of 12 whales instrumented with Fastloc‐GPS transmitters were studied during summer in Scoresby Sound and at their offshore winter ground in 2017–2019. An additional four narwhals provided detailed hydrographic profiles on both summer and winter grounds. Data on diving of the whales were obtained from 20 satellite‐linked time‐depth recorders and 16 Acousonde? recorders that also provided information on the temperature and depth of buzzes. In summer, the foraging whales targeted depths between 300 and 850 m where the preferred areas visited by the whales had temperatures ranging between 0.6 and 1.5°C (mean = 1.1°C, SD = 0.22). The highest probability of buzzing activity during summer was at a temperature of 0.7°C and at depths > 300 m. The whales targeted similar depths at their offshore winter ground where the temperature was slightly higher (range: 0.7–1.7°C, mean = 1.3°C, SD = 0.29). Both the probability of buzzing events and the spatial distribution of the whales in both seasons demonstrated a preferential selection of cold water. This was particularly pronounced in winter where cold coastal water was selected and warm Atlantic water farther offshore was avoided. It is unknown if the small temperature niche of whales while feeding is because prey is concentrated at these temperature gradients and is easier to capture at low temperatures, or because there are limitations in the thermoregulation of the whales. In any case, the small niche requirements together with their strong site fidelity emphasize the sensitivity of narwhals to changes in the thermal characteristics of their habitats.     

Novel psychrotolerant picocyanobacteria isolated from Chesapeake Bay in the winter

Picocyanobacteria are major primary producers in the ocean, especially in the tropical or subtropical oceans or during warm seasons. Many “warm” picocyanobacterial species have been isolated and characterized. However, picocyanobacteria in cold environments or cold seasons are much less studied. In general, little is known about the taxonomy and ecophysiology of picocyanobacteria living in the winter. In this study, 17 strains of picocyanobacteria were isolated from Chesapeake Bay, a temperate estuarine ecosystem, during the winter months. These winter isolates belong to five distinct phylogenetic lineages, and are distinct from the picocyanobacteria previously isolated from the warm seasons. The vast majority of the winter isolates were closely related to picocyanobacteria isolated from other cold environments like Arctic or subalpine waters. The winter picocyanobacterial isolates were able to maintain slow growth or prolonged dormancy at 4°C. Interestingly, the phycoerythrin‐rich strains outperformed the phycocyanin‐rich strains at cold temperature. In addition, winter picocyanobacteria changed their morphology when cultivated at 4°C. The close phylogenetic relationship between the winter picocyanobacteria and the picocyanobacteria living in high latitude cold regions indicates that low temperature locations select specific ecotypes of picocyanobacteria.     

Influences of Temperature and Desiccation on Breaking Diapause in the Gemmules of Eunapius fraqilis (Leidy)

Summary

Most specimens of Eunapius fraqilis in Gallup Pond (Connecticut) apparently formed gemmules in September and then died. The gemmules were initially in a protracted diapause which was gradually broken during the winter. They germinated in the pond between late March and late April. Gemmules collected during the fall did not germinate during four months when they were kept at 20°C. Other gemmules from the same collections, which were kept at 5°C for several months before they were placed at 20°C, exhibited good germination. Finally, gemmules that did not germinate following a cold treatment could be activated by drying them at 20°C for seven days and then maintaining them in pond water at 20°C. These results suggest that low temperature and desiccation are effective in breaking gemmule diapause of Eunapius fraqilis.     

BIOGEOGRAPHIC ANALYSIS OF THE ARMORED PLANKTONIC DINOFLAGELLATE CERATIUM IN THE NORTH ATLANTIC AND ADJACENT SEAS1

The distribution of the dinoflagellate genus Ceratium Schrank (Dinophyceae) in the North Atlantic and adjacent seas was studied by a combination of new observations on a large number of plankton samples collected from the northeastern Atlantic and North Sea, data from cruises off the east coast of North America and Caribbean Sea, and reports in the literature of the past 90 years. Seventy species were recorded, and their distribution was examined by several methods. Distribution maps were plotted for all species, and from these the ranges of temperature tolerance were derived. The 240 sets of data, which took the form of lists of species present in 5° latitude / longitude blocks obtained from the new work and the published material, were analyzed by clustering and ordination multivariate techniques using the programs Twinspan and Decorana. Analysis of the individual species showed that surface water temperature is the most important factor determining distribution and the number of species in a particular area. Warm water and /or low latitudes have many more species than cold waters and/or high latitudes. For example, at 5°N there are on average 23 species per block, whereas at 60° N there are only 8 species. On the basis of this work, the Ceratium species are divided into Group 1, Arctic-temperate species normally only found in water of less than 15°C; Group 2, cosmopolitan species, which are found virtually everywhere and are the species most likely to form blooms or “brown water”; Group 3, intermediate species, which extend into neither the coldest nor the warmest water; Group 4, temperate-tropical species, which have a lower temperature boundary of 5°–12° C; Group 5, warm-temperate-tropical species with a lower temperature boundary of 14°–15°C; and Group 6, tropical species, which are rarely found in water of less than 20° C. Analysis of the sample sites also confirmed the predominant influence of temperature, and the Atlantic Ocean was divided into four biogeographical zones of which the boundaries follow isotherms of surface water temperature. Zone 1 consists of the Arctic and subarctic area, with the southern boundary closely following the 10° mean annual temperature (MAT) line. Zone 2 is an intermediate or cold-temperate zone, of which the southern boundary follows the winter 10° C MAT isotherm or the similarly placed summer 15° isotherm. Zone 3 is the warm-temperate or subtropical zone, which is very broad. The southern boundary closely follows the 25°C summer isotherm. Zone 4 is the tropical zone, where water temperature is never likely to be much less than 23°C. These findings are discussed in relation to experimental work and environmental observations. We suggest that the genus Ceratium provides an excellent tool for defining ocean currents and temperature changes and may become of value in studies of global change.     

Effect of low and high temperatures on the photosynthetic performance of Lantana camara L. Leaves in darkness

Low and high temperatures are known as most important factors influencing plant performance and distribution. Plants of Lantana camara L. coming from two distinct geographical populations (Iberian Peninsula and Galápagos Islands) were cultivated in a common garden experiment, and their leaves were subjected to thermal treatments (from +20.0 to ?7.5°C during the winter and from +20.0 to +50.0°C during the summer) in a programmable water bath in darkness. Their photosynthetic performance and their recovery capacity after the thermal treatment were evaluated by measuring chlorophyll fluorescence, net photosynthesis rate, and leaf necrosis. In general, L. camara photosynthetic apparatus showed a wide range of temperature tolerance in darkness, showing optimal functioning of its photosystem II just after exposure to temperatures between ?2.5 and +35.0°C for the Iberian population and between +10.0 and +25.0°C for the Galápagos population. Just after exposure to low and high temperatures, gradual cold and heat-induced photoinhibition was recorded for both populations. After 24 h, leaves of L. camara demonstrated a great recovery capacity from ?2.5 to +42.5°C. However, leaves of the treatments from ?5.0°C down and +47.50°C up showed permanent damages to the photosynthetic apparatus and to the leaf tissues. Slight interpopulation differences were found only at extreme temperatures.