Length-weight relationships and relative conditions of two sciaenids Otolithes cuvieri Trewavas and Johnius elongatus Mohan from the Karachi coast

Estimates of length-weight relationship in Otolithes cuvieri justify separate equations for males (log W =-5.0100+3.1365 log L) and females (log W =-5.2000+3.1006 log L). Relative condition factor "Kn" was found to be 0.877-1.946 in males and 0.879-1.328 in females. High "Kn" values during March to September at 180-220 mm TL in either sexes are indicative of the maturation of gonads. Separate equations for length-weight relationship are also justified for males (log W = -5.1126 + 3.0690 log L) and females (log W = -5.6400 + 3.3070 log L) of Johnius elongatus . "Kn" values were found to be 0.924-1.894 for males and 0.894-1.087 for females. High "Kn" values during January-May and August-September at 130 mm TL onward are indicative of gonadal maturation.

Some aspects of reproductive biology of two sciaenids, Otolithes cuvieri Trewavas and Johnius elongatus Mohan: maturation, spawning, sex ratio and fecundity

The gonads of Otolithes cuvieri and Johnius elongatus are described in seven maturity stages. O. Cuvieri spawns once a year from April to September as evidence by ova diameter frequency distribution and GSI values. 50% maturity is attained at 210mm TL in males and 200mm TL in females. Fecundity ranged from 2387 to 104379 with a mean value of 33502. Log-Log relationship between fecundity and total lenght, body weight and ovary weight were determined. An overall sex ratio of 1.54:1.00 was unequal in favour of males. Johnius elongatus spawns twice a year from January-February to Aprile-May and from August to October as evidence by ova diameter frequency distribution and GSI values. 50% maturity is attained at 140-143mm TL in both sexes. Fecundity ranged from 4238 to 167669 with a mean value of 42818. Log-Log relationship between fecundity and total lenght, body weign and ovary weight were determined. An overall sex ratio of 1.00:1.20 was unequal in favour of females.

聚球藻Synechococcus sp.PCC7942高CO_2需求突变株的筛选及其超微结构观察(英文)

以单细胞蓝藻聚球藻Synechococcussp.PCC7942为材料,利用甲基磺酸乙酯(EMS)进行化学诱变获得了一个高CO2 需求突变株。它能在 4%CO2 下生长而不能在空气中生长。对突变株的初检表明:其回复突变率约为 10 -7。该突变株从高CO2 条件下转到空气中后,细胞在 2～ 3d内逐渐趋于死亡;其光合作用对外源无机碳的依赖性高于野生型细胞,碳酸酐酶活性也低于野生型细胞。在超微结构水平,突变株细胞内出现了不同类型的异常羧体:有的为棒状;有的为不规则状;有的为 空羧体",而且,类囊体周围糖原颗

ApcD is necessary for efficient energy transfer from phycobilisomes to photosystem I and helps to prevent photoinhibition in the cyanobacterium Synechococcus sp PCC 7002

Phyrobilisomes (PBS) are the major light-harvesting, protein-pigment complexes in cyanobacteria and red algae. PBS absorb and transfer light energy to photosystem (PS) II as well as PS I, and the distribution of light energy from PBS to the two photosystems is regulated by light conditions through a mechanism known as state transitions. In this study the quantum efficiency of excitation energy transfer from PBS to PS I in the cyanobacterium Synechococcus sp. PCC 7002 was determined, and the results showed that energy transfer from PBS to PS I is extremely efficient. The results further demonstrated that energy transfer from PBS to PS I occurred directly and that efficient energy transfer was dependent upon the allophycocyanin-B alpha subunit, ApcD. In the absence of ApcD, cells were unable to perform state transitions and were trapped in state 1. Action spectra showed that light energy transfer from PBS to PS I was severely impaired in the absence of ApcD. An apcD mutant grew more slowly than the wild type in light preferentially absorbed by phyrobiliproteins and was more sensitive to high light intensity. On the other hand, a mutant lacking ApcF, which is required for efficient energy transfer from PBS to PS II, showed greater resistance to high light treatment. Therefore, state transitions in cyanobacteria have two roles: (1) they regulate light energy distribution between the two photosystems; and (2) they help to protect cells from the effects of light energy excess at high light intensities. (C) 2009 Elsevier B.V. All rights reserved.

Selection and ultrastructural observation of a high-CO2-requiring mutant of cyanobacterium Synechococcus sp PCC7942

A high-CO2-requiring mutant of Synechococcus sp. PCC7942 las been isolated after chemical mutagenesis of ethyl methane sulphonate (EMS). It was able to grow at 4% CO2, but not under ambient CO2. The initial screening of the mutant showed that the genetic reversion rate was about 10(-7) and death occurred 2 -3 days after being transferred from 4% CO2 to the ambient air. Its photosynthetic dependence on external dissolved inorganic carbon was higher than that of the wild type cells, but its carbonic anhydrase activity was comparatively low. In the ultrastructural level, various types of aberrant carboxysomes appeared in the mutant cells: rod-shaped carboxysomes, irregular carboxysomes and the "empty-inclusion carboxysomes" with increasing number of glycogen granules surrounding the thylakoids. All these alterations indicated that the mutant was defective in utilizing the external CO2. The induction of carboxysomes by lower levels of CO2 and the biogenesis of carboxysomes are herein discussed.

Comparative Analysis of Fatty Acid Desaturases in Cyanobacterial Genomes

Fatty acid desaturases are enzymes that introduce double bonds into the hydrocarbon chains of fatty acids. The fatty acid desaturases from 37 cyanobacterial genomes were identified and classified based upon their conserved histidine-rich motifs and phylogenetic analysis, which help to determine the amounts and distributions of desaturases in cyanobacterial species. The filamentous or N-2-fixing cyanobacteria usually possess more types of fatty acid desaturases than that of unicellular species. The pathway of acyl-lipid desaturation for unicellular marine cyanobacteria Synechococcus and Prochlorococcus differs from that of other cyanobacteria, indicating different phylogenetic histories of the two genera from other cyanobacteria isolated from freshwater, soil, or symbiont. Strain Gloeobacter violaceus PCC 7421 was isolated from calcareous rock and lacks thylakoid membranes. The types and amounts of desaturases of this strain are distinct to those of other cyanobacteria, reflecting the earliest divergence of it from the cyanobacterial line. Three thermophilic unicellular strains, Thermosynechococcus elongatus BP-1 and two Synechococcus Yellowstone species, lack highly unsaturated fatty acids in lipids and contain only one Delta 9 desaturase in contrast with mesophilic strains, which is probably due to their thermic habitats. Thus, the amounts and types of fatty acid desaturases are various among different cyanobacterial species, which may result from the adaption to environments in evolution. Copyright (c) 2008 Xiaoyuan Chi et al.

Evidence for positive selection in phycoerythrin genes of red algae and cyanobacteria Prochlorococcus and Synechococcus

Because of the shortage of phycoerythrin (PE) gene sequences from rhodophytes, peBA encoding beta- and alpha-subunits of PE from three species of red algae (Ceramium boydenn, Halymenia sinensis, and Plocamium telfariae) were cloned and sequenced. Different selection forces have affected the evolution of PE lineages. 8.9 % of the codons were subject to positive selection within the PE lineages (excluding high-irradiance adapted Prochlorococcus). More than 40 % of the sites may be under positive selection, and nearly 20 % sites are weakly constraint sites in high-irradiance adapted Prochlorococcus. Sites most likely undergoing positive selection were found in the chromophore binding domains, suggesting that these sites have played important roles in environmental adaptation during PE diversification. Moreover, the heterogeneous distribution of positively selected sites along the PE gene was revealed from the comparison of low-irradiance adapted Prochlorococcus and marine Synechococcus, which firmly suggests that evolutionary patterns of PEs in these two lineages are significantly different.

海洋聚球蓝细菌（Synechococcus）的纯化鉴定及生理和生态分布特征

利用流式细胞仪分析了聚球蓝细菌在胶州湾的时空分布和营养盐的影响, 并对聚球蓝细菌亚群分化及其影响因子做了进一步探索。分离获得六株海洋聚球蓝细菌，分别定名为IOCAS0401、IOCAS0402、IOCAS0403、IOCAS0404、IOCAS0405、IOCAS0406。对其中两株（IOCAS0401、IOCAS0402）进行鉴定，并进一步研究了其生理生态特征。有三株菌（IOCAS0403、IOCAS0404、IOCAS0405）具有异养生长能力，选取其中两株（IOCAS0403、IOCAS0405）构建了遗传操作系统。具体内容摘要如下： 1、聚球蓝细菌在胶州湾的时空分布和营养盐的影响 胶州湾近一年的微微型浮游植物群落分析表明，聚球蓝细菌逐月的最高丰度中心有从湾外→湾口→湾内，再由湾内→湾口→湾外的变化趋势。在月变化中，聚球蓝细菌9月丰度最大，平均丰度为4.87×103 cells/ml，1-4月丰度很低，其中3月平均丰度最低为66 cells/ml。选取D5站的0 m和30 m作为表层和深层，对微微型浮游植物和营养盐的研究表明，在9、10月，N/P主要在10-30之间，聚球蓝细菌占优势51.6%（9月），98.5％（10月），其它月份大多数N/P<10或者>30，尤其以8月和11月最为显著，而这两个月也恰恰是超微真核浮游植物占优势92.1％（8月），84.8％（11月）。流式细胞仪数据表明，夏末和秋季部分站位会出现聚球蓝细菌的两个亚群，并且当N/P在33左右时可能会出现两个亚群分化，经过对N源的分析后发现，产生亚群分化时NO3-N/PO4-P在14左右。 2、 所分离到的六株聚球蓝细菌的吸收光谱表明，胶州湾的聚球蓝细菌色素种类十分丰富，基本都含有叶绿素a和藻红蛋白（PE），同时也有含藻蓝蛋白（PC）的种群。研究中发现有三株菌具有兼性异养生长能力，当有光照的时候，合成色素，自养生长进行产氧光合作用，没有光照时，色素逐渐消失，启动异养生长的代谢过程。 3、 利用流式细胞仪分析黄海近海水样中聚球蓝细菌种群组成，发现主要有不同藻红蛋白含量的两个类群组成，流式细胞仪分选后，用SN培养基培养纯化得到两个亚群优势种聚球蓝细菌IOCAS0401和IOCAS0402。荧光显微镜下镜检，两株菌在蓝色激发光（450-490 nm）下发桔红色荧光，并且IOCAS0401的荧光较IOCAS0402强。扫描电镜观察发现IOCAS0401呈椭圆形，长轴大约1.2 μm左右；IOCAS0402近似球形，直径约有0.6 μm左右。吸收光谱的检测表明，两者都有叶绿素a和藻红蛋白的特征吸收峰。其中IOCAS0401有藻尿胆素（PUB）和藻红胆素（PEB）吸收锋，而IOCAS0402只有PEB的吸收峰，两者均无藻蓝蛋白（PC）吸收锋。通过16S rDNA测序分析，结果表明两株菌都位于MC-A中的clade II类群，与从日本海域分离获得的MBIC10224菌株有较高的亲缘关系，虽然这三株菌都归为clade II，但单独成一分支，表明它们带有明显的西太平洋特色。 4、 选取其中两株IOCAS0403和IOCAS0405构建遗传系统，抗生素图谱表明，IOCAS0403对四环素有抗性，自然转化结果显示，IOCAS0403不能自然转化，IOCAS0405具有自然转化能力，同时两者都不能进行接合转移。

微藻脂肪酸去饱和酶基因的比较基因组学分析及重要基因功能的验证

不饱和脂肪酸是机体生物膜的重要组成成分，对生物膜结构、机能、相转变、通透性的调节及相关过程的调控有重要作用。并且，它参与细胞生物化学反应、转运过程和细胞应激反应，影响脂肪代谢、寻靶作用、免疫反应、耐寒、抗氧化等生理过程。此外，不饱和脂肪酸还是哺乳动物体内生成前列腺素、凝血哑烷和白三烯等激素的前体，具有提高人体免疫力、预防心血管疾病和癌症等重要的生理功能。本文对微藻中脂肪酸去饱和酶基因进行了比较基因组学分析；分离并验证了模式绿藻莱茵衣藻中Δ12去饱和酶基因的功能；克隆了南极小球藻NJ-7不饱和脂肪酸合成途径中的内质网型Δ12、Δ15去饱和酶基因和叶绿体型Δ12基因，并对内质网型Δ12基因的功能进行了研究。 1、对已测序的37株蓝藻的脂肪酸去饱和酶基因进行比较基因组学分析，发现，丝状或固氮蓝藻中具有的脂肪酸去饱和酶的种类一般多于单细胞蓝藻；海洋来源的聚球藻和原绿球藻的酰基-脂去饱和途径明显不同于其他来源的蓝藻，这两属的蓝藻与其他蓝藻可能具有不同的系统发育史；与嗜温蓝藻相比，三个嗜热蓝藻藻株，Thermosynechococcus elongatus BP-1， Synechococcus sp. JA-2-3B'a(2-13)，sp. JA-3-3Ab只含有Δ9去饱和酶基因，这可能与它们的生长环境（温泉）有关。 2、对已测序的7株真核微藻的脂肪酸去饱和酶基因进行比较基因组学分析，发现，真核微藻不饱和脂肪酸合成途径具有多样性。绿藻衣藻和团藻，O. tauri和O. lucimarinus，硅藻三角褐指藻和伪矮海链藻中均存在两条不饱和脂肪酸合成途径，原核途径和真核途径。原核途径位于叶绿体，真核途径位于内质网，但合成的脂肪酸产物有所不同。原始红藻C. merolae只含有3个去饱和酶基因，2个Δ9基因和1个Δ12基因。不饱和脂肪酸合成缺失了一条原核途径，明显不同于其他蓝藻、绿藻、硅藻和高等植物，这可能是由于它们的特定的生长环境（酸性火山温泉）导致的。 3、通过比较基因组学分析，从模式绿藻莱茵衣藻中发现了一个可能的内质网型Δ12去饱和酶基因（135825），以酿酒酵母作为表达系统，验证了该基因的功能，为明确该模式藻的脂肪酸合成途径提供了依据。 4、从南极小球藻NJ-7中克隆了参与不饱和脂肪酸合成途径的内质网型Δ12、Δ15去饱和酶基因和叶绿体型Δ12基因的部分cDNA序列，并利用RACE方法获得了内质网型Δ12基因的全长，以酿酒酵母作为表达系统，对该基因的功能进行了研究。 本研究首次利用比较基因组学的方法分析了37株蓝藻和7株真核微藻中的不饱和脂肪酸合成途径，在此基础上研究了莱茵衣藻135825基因的功能。并从南极绿藻小球藻中克隆了参与不饱和脂肪酸合成途径的内质网型Δ12、Δ15去饱和酶基因和叶绿体型Δ12基因，为进一步研究温度调节去饱和酶表达的模式，明确微藻低温适应的分子机理奠定了基础。

Determinação da estrutura e estudo da função da metalotioneína de Synechococcus com ferramentas da bioinformática.

Este trabalho abordou a análise estrutural das MTs a fim de se modelar esta proteína e com isso compreender melhor o funcionamento da mesma. O conhecimento da cianobactéria e uma completa análise da MT poderia ser muito útil em um estudo de utilização desta na técnica da biorremediação para remover metais pesados do solo e da água decorrentes das praticas agrícolas atuais.

Continuous Plankton Records - Persistence In Time-Series And The Population-Dynamics Of Pseudocalanus-Elongatus And Acartia-Clausi

Rates of population increase in early spring and the sizes of overwintering stocks were calculated for the planktonic copepods Pseudocalanus elongatus and Acartia clausi for a set of areas covering the open waters of the north-east Atlantic Ocean and the North Sea for the period 1948 to 1979. For both species, the rates of population increase were higher in the open ocean than in the North Sea and appear to be related to temperature. The overwintering stocks in the North Sea were larger than those in the open ocean and are probably related to phytoplanton concentration. P. elongatus shows higher overwintering stocks and lower rates of population increase than A. clausi, resulting in different levels of persistence in the stocks of the two species. It is suggested that this difference in persistence is responsible for differences between the two species with respect to geographical distribution in summer and different patterns of year-to-year fluctuations in abundance.