An approach to estimating rockfish biomass based on larval production, with application to Sebastes jordani

An assessment of the total biomass of shortbelly rockfish (Sebastes jordani) off the central California coast is presented that is based on a spatially extensive but temporally restricted ichthyoplankton survey conducted during the 1991 spawning season. Contemporaneous samples of adults were obtained by trawl sampling in the study region. Daily larval production (7.56 × 1010 larvae/d) and the larval mortality rate (Z=0.11/d) during the cruise were estimated from a larval “catch curve,” wherein the logarithm of total age-specific larval abundance was regressed against larval age. For this analysis, larval age compositions at each of the 150 sample sites were determined by examination of otolith microstructure from subsampled larvae (n=2203), which were weighted by the polygonal Sette-Ahlstrom area surrounding each station. Female population weight-specific fecundity was estimated through a life table analysis that incorporated sex-specific differences in adult growth rate, female maturity, fecundity, and natural mortality (M). The resulting statistic (102.17 larvae/g) was insensitive to errors in estimating M and to the pattern of recruitment. Together, the two analyses indicated that a total biomass equal to 1366 metric tons (t)/d of age-1+ shortbelly rockfish (sexes combined) was needed to account for the observed level of spawning output during the cruise. Given the long-term seasonal distribution of spawning activity in the study area, as elucidated from a retrospective examination of California Cooperative Oceanic Fisheries Investigation (CalCOFI) ichthyoplankton samples from 1952 to 1984, the “daily” total biomass was expanded to an annual total of 67,392 t. An attempt to account for all sources of error in the derivation of this estimate was made by application of the delta-method, which yielded a coefficient of variation of 19%. The relatively high precision of this larval production method, and the rapidity with which an absolute biomass estimate can be obtained, establishes that, for some species of rockfish (Sebastes spp.), it is an attractive alternative to traditional age-structured stock assessments.

棕色固氮菌突变株DJ35 中钼铁蛋白和HBP59 蛋白的研究—纯化特性及晶体生长

我们从A. vinelandii突变株DJ35中纯化得到了ΔnifE Av1，并通过与OP Av1相比较对其特性进行了研究。虽然ΔnifE Av1以四聚体形式(α2β2)存在，但却表现出两种天然电泳行为。与OP Av1相比，ΔnifE Av1中的金属含量较低，每个蛋白分子仅含9.96个铁原子、0.36个钼原子。OP Av1和ΔnifE Av1的吸收光谱相似，均在280 nm附近出现蛋白吸收峰，在300-600 nm波长范围内光吸收普遍降低，并无特征峰出现。虽然ΔnifE Av1可见光区域CD谱的摩尔消光系数（Δε）总比OP Av1小，但在520nm区域附近摩尔消光系数减少的相对值明显大于在450nm附近摩尔消光系数减少的相对值。ΔnifE Av1的EPR信号明显与OP Av1不同，在g≈3.7处的EPR信号完全消失，在g≈4.3 和2.0处的EPR信号强度也分别降低了75%和50%以上。ΔnifE Av1不能与Fe蛋白组成活性单位，但被FeMoco激活后可与Fe蛋白组成活性单位。上述结果表明, ΔnifE Av1不含FeMoco，但具有与OP Av1相同的P-cluster。 我们在纯化ΔnifE Av1的过程中，发现一个类似OP Av1的β亚基的污染蛋白，经MALDI-TOF质谱鉴定这种蛋白是棕色固氮菌中一预测基因的产物。通过改进纯化方法, 我们首次得到80%电泳纯的蛋白，并将其命名为HBP59蛋白。HBP59为一单体蛋白，分子量约为59k Da。金属测定结果表明每个蛋白分子中含有0.42个铁原子。HBP59蛋白的可见光谱表现出典型的血红素蛋白光谱特征，还原态的HBP59蛋白在421nm处有最大吸收峰，同时在517nm、556nm处有两个伴随肩峰出现, A421/A280仅为0.146。HBP59蛋白氧化后，吸收峰发生蓝移，最大吸收峰从421nm移到413nm，517nm和556nm处的肩峰消失，A413/A280为0.168。HBP59蛋白的可见光区圆二色谱比较复杂，正峰出现在420nm, 406nm, 379nm 和364nm; 其摩尔消光系数分别为0.75, 0.94, 0.68 和 0.99;负峰出现在433 nm 和392nm，其摩尔消光系数分别为-1.13 和-0.78。血红素滴定实验结果说明每个HBP59蛋白分子结合了0.1个血红素，但每个蛋白分子具有最大结合1个血红素的能力。这低结合能力与这低比率的比率是非常一致的。该蛋白对温度相对敏感，高于40℃蛋白开始沉淀。上述结果说明HBP59是一个结合具有低自旋和不对称的血红素的蛋白，它在菌体内可能并未扮演贮藏血红素的角色，而是可能参与血红素的运输或附着。 此外，经过结晶条件的大量筛选后获得了ΔnifE Av1和ΔnifH Av1的优质小单晶,并对HBP59的晶体培养进行了初步探索。

Trawling pull exerted by a trawler: a method of estimation from propeller dimensions and its comparison with sea measurements

The proper matching of the pull exerted by a trawler and the size of trawl is important for maximizing the catching efficiency. The available pull is more dependent on the propeller and its working conditions than the installed engine power. The normal practice is to directly connect net size to the installed power in the boat by formulae without reference to the prope1ler dimensions or the available trawling pull and this is not adequate to find out the optimum combination. By the method outlined in this paper, the accurate calculation of trawling pull is possible by taking into account only the propeller diameter, pitch and r. p. m. The predictions by the method are compared for trawlers with powers between 30 and 60 hp and agreement is found to be within + 5%. The power absorbed by the propeller in trawling condition can also be calculated by this method for checking whether the engine is being overloaded.

Preservation of fish by freezing and glazing. Pt. 2. Keeping quality of fish with particular reference to yellow discolouration and other allied organoleptic changes on prolonged storage

Organoleptic observations of quick, slow and block frozen, glazed and stored fish were recorded at regular intervals. Glazing was renewed at intervals of four weeks. Development of yellow discolouration in the case of white pomfret was followed. Keeping quality of glazed fish was better than unglazed frozen fish. Yellow discolouration could be controlled by ascorbic acid for 42 months and by a mixture of sodium chloride and glucose for 52 months.

Field emission from tetrahedrally bonded amorphous carbon

The field emission behaviour of a series of Tetrahedrally Bonded Amorphous Carbon (ta-C) films has been measured. The films were produced using a Filtered Cathodic Vacuum Arc System. The threshold field for emission and current densities achievable have been investigated as a function of sp3/sp2 bonding ratio and nitrogen content. Typical as-grown undoped ta-C films have a threshold field of order 10-15 V/μm and optimally nitrogen-doped films exhibit fields as low as 5 V/μm. The emission as a function of back contact and front surface condition has also been considered and shows that the back contact has only a minor effect on emission efficiency. However, after etching in either an oxygen or hydrogen plasma, the films show a marked reduction in threshold field, down to as low as 2-3 V/μm, and a marked improvement in emission site density.

云南基诺族及汉族特发性全面强直-阵挛性癫(癎)与CLCN2基因的相关性

目的 研究氯离子通道CLC-2基因是否与中国云南地区基诺族及汉族特发性全面强直-阵挛性癫(癎)(IGTCS)相关.方法 以14例云南西双版纳傣族自治州景洪市基诺乡基诺族IGTCS患者及其16名未发病亲属、67例云南籍汉族IGTCS患者及57名云南籍汉族健康体检者为对照,对常染色体3q26上CLCN2基因的内含子2及外显子5、19(内含子18)进行研究,采用PCR及直接基因测序技术,应用病例-对照研究法对CLCN2基因与云南基诺族及汉族IGTCS进行相关性分析.结果 CLCN2基因的内含子2及外显子5、19在病例组和对照组中均没有发现已报道的易患突变,但我们在对外显子19的序列测定过程中发现了其上游内含子18的146位上存在1个单核苷酸多态性位点:146T→C.该位点的3种基因型(TT、TC、CC)在汉族病例组(9、3、29例)和汉族对照组(22、9、26例)之间的分布差异有统计学意义(x2=16.079,P＜0.05);在基诺族组(基诺族病例组+基诺族亲属组,6、12、12例)与汉族对照组(22、9、26例)之间分布差异亦有统计学意义(x2=7.027,P＜0.05).汉族病例组与汉族对照组间TT型与非TT型基因型(分别为9、32例和22、35例)、TC型与非TC型基因型(分别为3、38例和9、48例)比较差异有统计学意义(x2=10.694,OR=4.121,P＜0.05;x2=11.592,OR=0.238,P＜0.05).结论 CLCN2基因内含子18的多态性位点146T→C可能是中国云南地区基诺族与汉族IGTCS患者的1个相关性位点,且在本组有限的样本数量研究中,此SNP位点在两个民族IGTCS患者之间的分布无民族差异.基因型TT为IGTCS的1个保护性因素,基因型TC则增加了患者的易患性.