大亚湾夏季和冬季超微型浮游生物的时空分布及环境调控

通过流式细胞法, 于2015 年夏季(7 月)和冬季(12 月)对大亚湾超微型浮游生物(聚球藻、超微型真核藻类和异养细菌)的时空变化及环境调控进行了比较研究。结果表明, 夏季聚球藻、超微型真核藻类和异养细菌的丰度分别为(44.56±46.26)×103 cells·mL^–1、(3.00±4.50)×103 cells·mL^–1 和(12.31±7.54)×105 cells·mL^–1, 冬季的丰度分别为(12.48±3.96)×103 cells·mL^–1、(0.78±0.71)×103 cells·mL^–1和(3.83±1.39)×105 cells·mL^–1。超微型浮游生物的丰度呈现为夏季高于冬季, 受到温度、溶解无机氮组成和透明度的影响。夏季表层丰度明显高于底层, 但冬季表底层无明显差异。在水平分布上, 夏季湾内高营养盐基本对应高丰度, 但石化区附近(S3 站)营养盐高丰度却较低, 范和港(S1 站)低营养盐丰度却较高; 湾口和湾外区主要受到外海水的影响, 超微型浮游生物的3 个类群丰度均较低。在沿岸流、海水垂直混合、外源营养盐输入等多个因素共同影响下, 冬季湾中部和大鹏澳附近的聚球藻丰度较高, 超微型真核藻类在湾口和范和港丰度较高, 异养细菌在湾内和湾西部丰度较高。两个季节超微型真核藻类和异养细菌呈显著正相关。     

冬季南海南部微微型浮游植物分布及其影响因素

于2011年11月28日至2012年1月12日调查了南海南部113°E断面(5—13°N)微微型浮游植物的空间分布,并分析了其分布与环境因子的关系。结果表明,调查海域原绿球藻,聚球藻和微微真核生物所有站位水柱丰度的均值分别为(1.71±0.47)×104、(1.50±0.72)×103和(1.30±0.50)×102个/m L,原绿球藻比聚球藻和微微型真核生物分别高1和2个数量级。原绿球藻主要分布在100m以浅,聚球藻主要分布在75m以浅且在25m丰度最高,而微微型真核生物主要分布在100m以浅,在25—75m内丰度最高,与叶绿素a浓度次表层最大值层相吻合。在9—11°N之间,原绿球藻和聚球藻最大值层上移且其最大值显著低于周围水体最大值;而在11—13°N之间,微微型真核生物出现次表层最大值,丰度明显高于周围水体最大值,这可能分别与调查期间采样区域中尺度冷涡上升流和中尺度暖涡下降流引起的水体运动有关。结果还显示,在深海寡营养站位,原绿球藻、聚球藻和微微型真核生物的碳生物量分别占微微型生物总碳生物量的(59.16±13.74)%、(23.86±10.83)%和(16.97±5.51)%,表明原绿球藻在光合微微型生物中占绝对优势。此外,相关性分析结果表明,聚球藻丰度与水体温度呈显著正相关,与盐度呈显著负相关;微微型真核生物与硝酸盐和磷酸盐浓度呈显著负相关。     

海洋微型和微微型浮游生物的区域分布与影响因素

微型和微微型浮游生物几乎存在于所有的海洋生态系统中,其群落遍布世界各大洋。在大部分海域,微型浮游生物的优势类群为鞭毛藻;原绿球藻是贫营养海域的优势类群,而聚球藻、微微型真核生物和异养细菌主要在营养盐丰富的海域出现,在热带、亚热带和温带的富营养区域占优势。温度、盐度、光照、营养盐可得性、水体稳定性和摄食压力是影响微型和微微型浮游生物的主要因素,各海域主要调控因子的不同造成了微型和微微型浮游生物类群和丰度分布的差异。本文主要综述海洋微型和微微型浮游生物类群检测方法、区域分布特点及其受环境影响的研究概况,并提出了今后的重点研究内容和发展方向。     

南大洋蓝细菌和微微型光合真核生物的丰度与分布

1989/1990年南半球夏季,在自Valporaiso至Melbourne的南太平洋、南大西洋和南印度洋的广阔海域观测研究了表层水微微型光合浮游生物,包括蓝细菌和微微型光合真核生物的丰度与分布及其环境制约.结果表明,蓝细菌的丰度以亚热带海域最高,亚南极海域次之,南极海域最低,总的分布范围为 1.34～5.13 log(cell/cm³).蓝细菌丰度随纬度的增高和水温的降低而降低,其对数值与水温呈现极好的正相关(P<0.001),即使在水温变幅仅-0.3～2.1℃的绕极海域观测结果也是如此.这充分证明了蓝细菌在极地海洋的存在和水温是制约其丰度与分布的主要因子.而微微型光合真核生物丰度对水温变化的反应不如蓝细菌敏感,其变化幅度为1.54～4.50log(cell/cm³),然而在绕极海域其对数值与水温呈现极好的负相关(P<0.001),这可能是由于随着水温降低,距冰缘区越近,表层水体稳定度增大,有利于真核生物增长所致.     

青岛近海及其临近海域冬季微微型浮游植物的分布

微微型浮游植物（0.2～2.0 μm） 是海水中最小的自养浮游生物, 在世界各海域广泛分布, 并在海洋有机物质循环中起着非常重要的作用.利用荧光显微技术对青岛近海及其邻近海域冬季微微型浮游植物丰度进行了调查,研究了微微型浮游植物的空间变化和昼夜变化的特征, 并分析了微微型浮游植物丰度与环境因子的相关性. 结果显示, 冬季该海域以富含藻红素（Phycoerythrin-rich, PE）的聚球藻(Synechococcus, Syn)细胞占优势,微微型真核藻类（Picoeukaryote, Euk）次之,而富含藻蓝素（Phycocyanin-rich, PC）的聚球藻细胞数量很低, 未发现原绿球藻（Prochlorococcus, Pro）的存在.Syn 的变化范围为8.97×10³～1.95×10⁵ cells·ml^-1, 平均4.67×10⁴ cells·ml^-1; Euk的变化范围为1.95×10²～1.01×10⁴ cells·ml^-1, 平均2.39×10³ cells·ml^-1. Syn丰度在胶南以南海域出现高值区域, 在即墨海域和崂山东南海域出现低值区域. Euk丰度在日照海域出现高值区域; 崂山海域为低值区域; 各水层Syn和Euk丰度均无明显差异(P﹥0.05). 对胶州湾中部连续站4层水体的24 h昼夜连续变化进行观测发现, Syn、Euk丰度都有明显昼夜波动.相关性分析表明： Syn与温度、 电导率呈正相关, 与溶氧浓度呈显著负相关; Euk与盐度和溶氧浓度呈显著负相关. 微微型浮游植物对总浮游植物生物量的贡献约为20％.     

SUMMER DISTRIBUTION OF PICOPHYTOPLANKTON IN THE NORTH YELLOW SEA

 利用荧光显微技术(Epifluorescence microscopy, EFM)对2006年夏季北黄海水域80个站点的微微型浮游植物进行了检测, 并对其在平面和垂直分布上的变化以及昼夜变化情况进行了研究。检测到聚球藻(Synechococcus, Syn)和真核球藻(Picoeukaryotes, Euk)两类微微型浮游植物, 未检测到原绿球藻(Prochlorococcus, Pro), 其中Syn以富含藻红素的Syn细胞(PE细胞)为优势种类, 而富含藻蓝素的Syn细胞(PC细胞)数量较少。在荣城湾以东的水域, 各水层Syn和Euk的丰度都较其它水域的高。Syn在北黄海冷水团及附近水域下30 m深处和底层水体中出现明显的低值区, Euk丰度受冷水团影响不明显。在垂直分布上, 水表层和水下10 m深处Syn的丰度高于水下30 m深处和底层, 而Euk在垂直分布上无明显差异。在昼夜变化上, 各水层Syn、Euk丰度的白昼与夜间变化趋势无明显区别。     

夏、冬季南海北部浮游植物群落特征

对2009年7月19日—8月16日和2010年1月6—30日南海北部(18°—23.5°N、109°—120°E)两个航次的浮游植物样品应用Utermhl方法进行了分析鉴定。结果如下:夏季样品鉴定浮游植物4门72属150种,浮游植物细胞丰度范围为(0.16—6001.78)×103个/L,平均细胞丰度为26.49×103个/L,硅藻的平均细胞丰度为25.81×103个/L,主要优势种属有铁氏束毛藻(Trichodesmium thiebautii)、菱形海线藻(Thalassionema nitzschioides)、柔弱伪菱形藻(Pseudo-nitzschia delicatissima)及裸甲藻(Gymnodinium spp.)等;冬季样品鉴定浮游植物4门58属168种,浮游植物细胞丰度范围为(0.08—37.52)×103个/L,浮游植物平均细胞丰度为2.69×103个/L,硅藻的平均细胞丰度为2.49×103个/L,主要优势物种为菱形海线藻、伏氏海线藻(Thalassionema frauenfeldii)及短刺角毛藻(Chaetoceros messanensis)等;夏季调查区5m层浮游植物细胞丰度的平面分布由近岸到外海迅速减少,高值区主要在广东东部近岸及海南东部近岸;冬季则在珠江口近岸和海盆区出现较高值。两次调查中,浮游植物细胞丰度在浅水站位(200m)远高于深水站位(200m);较冬季相比,夏季浮游植物平均细胞丰度偏高,但物种丰富度却略偏低。夏、冬季浮游植物的香农-威纳多样性指数平均值分别为2.12和2.36,Pielou均匀度指数平均值分别为0.79和0.81。两个航次调查中,浮游植物细胞丰度均与盐度表现出显著性负相关性;在冬季还与磷酸盐浓度表现出显著性负相关性。     

盐湖微微型浮游植物多样性研究进展

盐湖在地球表层分布较广,中国是世界上盐湖分布稠密的国家。尽管盐湖生态环境极端恶劣,但它们依然是陆地特别是高原生态系统中十分重要的组成部分。微微型浮游植物(Picophytoplankton)通常是指粒径在0.2—3μm之间的光合自养型浮游生物,在这一生态类群中既有原核生物也有真核生物。微微型浮游植物不仅是海洋生态系统中生物量和生产力的最重要贡献者,也是盐湖生态系统最重要的组成部分。最近的调查数据显示,在东非Bogoria和Nakuru苏打盐湖中微微型浮游植物的生产力占整个浮游植物生产力的53%—68%。迄今为止,对盐湖微微型浮游植物多样性的研究多集中于盐田(Solar salterns)、盐池(Saline ponds)以及碱湖(Soda lakes)等超盐水体中;超盐盐湖中最常见的微微型浮游植物主要是蓝细菌(Cyanobacteria)类群,包括席蓝细菌属(Phormidium)、节旋藻属(Arthrospira)和隐杆藻属(Aphanothece)。分子生物学的研究显示,低碱浅水盐湖中微微型浮游植物具有丰富的多样性,主要类群是微微型原核浮游植物,还有部分种类与真核藻类质体序列高度相似。盐湖生态系统中微微型浮游植物群落结构演替变化的研究已经逐渐引起更多研究者的关注。已有的研究资料显示,水体矿化度是影响微微型浮游植物平面分布及群落结构组成的重要因子;光照、营养成分和温度等也会影响盐湖水体中微微型浮游植物平面分布及群落结构组成。综述了国内外对不同类型盐湖生态系统中微微型浮游植物多样性研究的概况,探讨了不同地理区域各种盐湖中微微型浮游植物群落结构的演替变化,并就我国未来加强盐湖中微微型浮游植物多样性构成、分布与变动及驱动变化的因子等研究提出了建议。     

1998/1999年南极普里兹湾邻近海域浮游植物的分布特征

中国第15次南大洋考察从普里兹湾邻近海域获得25个测站的浮游植物样品,主要研究了其种类组成、分布及其与环境的关系.浮游植物有5门16科21属48种(变种和变型),浮游植物平均细胞密度为22.46×103个/dm3,其中以硅藻类占优势(84.51%).浮游植物分布以近海岸陆架区的细胞密度最高(46.03×103个/dm3),其次为陆坡(4.40×103个/dm3),深海区最低(3.34×103个/dm3).表层叶绿素a浓度为0.16～3.99 μg/dm3,普里兹湾内和湾西部四女士浅滩海域浓度在3.5 μg/dm3以上;平面分布趋势浓度从湾内向西北方向递减,深海区浓度在0.5 μg/dm3以下.浮游植物优势种为硅藻的短拟脆杆藻(Fragilariopsis curta).浮游植物垂直分布密集区位于0～50 m水层,100 m或100 m以下水层随深度的增加而细胞密度逐渐减少,200 m水层稀少或未见.其密集区位于普里兹湾近岸陆架区,而陆坡及深海区细胞密度显著减少.叶绿素a浓度的最大值同样分布在25 m或50 m层,50 m以下的浓度随深度的增加而降低,200 m层叶绿素a浓度分布范围为0.01～0.95 μg/dm3.粒径分级叶绿素a浓度以微小型浮游生物的贡献占优势(56%),微型浮游生物的贡献占24%,微微型浮游生物的贡献占20%.经回归统计分析,浮游植物细胞丰度(y)与水温(T)、盐度成正相关,与营养盐(PO4 (P)、NO-3 (N)、SiO3 (Si))成显著负相关.     

深层海洋浮游植物研究综述

对深层海洋(200 m)浮游生物的研究是我国海洋浮游生物研究的前沿,已有的深层海洋浮游生物知识是我国相关研究的基础。浮游植物需要阳光进行光合作用,大多数浮游植物沉降到深海中会死亡,但有些浮游植物却能在深海中生存。综述深层海洋中存活的浮游植物的研究进展,为我国的研究提供参考。在深层海洋发现的浮游植物(2"m)种类不多,共有18种,最深分布在4000 m,颗石藻的丰度大于硅藻和甲藻,最大丰度为2220个/L,出现在500 m。在1911—1985年期间,曾经发现橄榄绿细胞,由于研究手段有限,一直没有对其进行分类学研究。1985年以后的研究怀疑这些橄榄绿细胞就是聚球藻蓝细菌,聚球藻蓝细菌在太平洋、大西洋和地中海的几个站位能分布到2750 m,在深层海洋的最大丰度为3.5×105个/mL,出现在800 m。在许多海区200—700 m发现有浮游植物色素荧光的高值,但对引起高值的原因尚不清楚。浮游植物生物量在深层海洋的垂直剖面研究不多,已有的研究表明浮游植物生物量在300 m以深为0.001—0.1"g C/L,且其随深度增加而降低。     

Race and Racism in America and in Anthropology

Race in North America: Origin and Evolution of a Worldview . Audrey Smedley
Anthropology and Race . Eugenia Shanklin     

Degradation and conversion of somatostatin in normal and diabetic rats in vivo and in vitro

Plasma somatostatin-like immunoreactivity in the portal and jugular veins of streptozotocin diabetic rats was compared with that in normal control rats. In the diabetic group, somatostatin levels in the portal (p less than 0.05) and jugular (p less than 0.01) veins were both elevated compared with those in the control group. Moreover, the degree of elevation was greater in the jugular vein than in the portal vein. To further investigate the role of the liver in the clearance of somatostatin-28 in vivo, 2 micrograms of somatostatin-28 was administered as a bolus into the external jugular vein of intact and functionally hepatectomized rats. The mean half-time of somatostatin-28 was significantly longer in intact diabetic rats than in controls (p less than 0.05). The functional hepatectomy did not cause a significant difference in the half-time in diabetic rats but made it longer in control rats. These results suggest that the longer half-time of somatostatin-28 in diabetic rats in vivo is due to its slower hepatic clearance. The hepatic clearance of somatostatin-28 and somatostatin-14 was further studied in vitro using a recirculating liver perfusion method. The hepatic clearance of 1.2 nM of either somatostatin-28 or somatostatin-14 was significantly lower in diabetic rats than in controls (p less than 0.01). This indicates that elevated plasma somatostatin levels in diabetic rats are caused at least in part by decreased hepatic clearance of somatostatin.(ABSTRACT TRUNCATED AT 250 WORDS)     

Electroejaculation in chimpanzees and gorillas and artificial insemination in chimpanzees

Electroejaculation was performed in 3 chimpanzees, 1 pygmy chimpanzee, and 2 gorillas with an instrument that delivers a modified sine wave current with a frequency of 24 Hz. The current stimuli were applied by a rectal probe with longitudinal electrodes. The electrical parameters varied from 6 to 12 V and from 30 to 40 mA for response of erection and lay between 8 and 18 V and between 40 and 145 mA during semen emission. Eleven chimpanzee semen samples showed the following data (x ± SD): total volume 1.9 ± 1.3 ml, volume of the liquid fraction 0.3 ± 0.2 ml, spermatozoa per ejaculate 743 ± 376 × 10⁶, sperm motility 52.7 ± 9.6%, morphologically abnormal spermatozoa 12.2 ± 7.5%. From an adult gorilla, three semen samples were collected, in each case without spermatozoa. The electrostimulation of a 6-year-old gorilla led to an erection, but not to semen emission. Three female chimpanzees were inseminated with fresh or frozen semen, each of them within three different estrous cycles. None of these inseminations led to a pregnancy.     

Variation in infectivity and aggressiveness in space and time in wild host-pathogen systems: causes and consequences

Variation in host resistance and in the ability of pathogens to infect and grow (i.e. pathogenicity) is important as it provides the raw material for antagonistic (co)evolution and therefore underlies risks of disease spread, disease evolution and host shifts. Moreover, the distribution of this variation in space and time may inform us about the mode of coevolutionary selection (arms race vs. fluctuating selection dynamics) and the relative roles of G × G interactions, gene flow, selection and genetic drift in shaping coevolutionary processes. Although variation in host resistance has recently been reviewed, little is known about overall patterns in the frequency and scale of variation in pathogenicity, particularly in natural systems. Using 48 studies from 30 distinct host–pathogen systems, this review demonstrates that variation in pathogenicity is ubiquitous across multiple spatial and temporal scales. Quantitative analysis of a subset of extensively studied plant–pathogen systems shows that the magnitude of within‐population variation in pathogenicity is large relative to among‐population variation and that the distribution of pathogenicity partly mirrors the distribution of host resistance. At least part of the variation in pathogenicity found at a given spatial scale is adaptive, as evidenced by studies that have examined local adaptation at scales ranging from single hosts through metapopulations to entire continents and – to a lesser extent – by comparisons of pathogenicity with neutral genetic variation. Together, these results support coevolutionary selection through fluctuating selection dynamics. We end by outlining several promising directions for future research.     

Trajectories and Constraints in Brain Evolution in Primates and Cetaceans

A negative allometric relationship between body mass (BM) and brain size (BS) can be observed for many vertebrate groups. In the past decades, researchers have proposed several hypotheses to explain this finding, but none is definitive and some are possibly not mutually exclusive. Certain species diverge markedly (positively or negatively) from the mean of the ratio BM/BS expected for a particular taxonomic group. It is possible to define encephalization quotient (EQ) as the ratio between the actual BS and the expected brain size. Several cetacean species show higher EQs compared to all primates, except modern humans. The process that led to big brains in primates and cetaceans produced different trajectories, as shown by the organizational differences observed in every encephalic district (e.g., the cortex). However, these two groups both convergently developed complex cognitive abilities. The comparative study on the trajectories through which the encephalization process has independently evolved in primates and cetaceans allows a critical appraisal of the causes, the time and the mode of quantitative and qualitative development of the brain in our species and in the hominid evolutionary lineage.     

Aminoacylation in Sulfolobus acidocaldarius and in methanogenic and halophilic archaebacteria

Abstract Phenylalanyl-tRNA synthetase (PRS) from the sulphur-metabolizing thermoacidophilic archaebacterium Sulfolobus acidocaldarius has been purified 150-fold using different chromatographic steps. The enzyme has a M _r of 270 000 and exhibits considerable thermostability in a temperature range up to 90°C with optimal activity at 70°C. Conservation of antigenic determinants could not be detected by antibodies against various PRS of all primary kingdoms. As a further means to detect traits of phylogenetic relationship, the cross-species reactivity between PRS and tRNAs of organisms from the three branches of archaebacteria and from all primary kingdoms reveals the group character of all 3 branches of the archaebacterial domain, the sulphur-metabolizing, methanogenic and halophilic archaebacteria.