Insights into the divergent evolution of the oceanic squid Sthenoteuthis oualaniensis (Cephalopoda: Ommastrephidae) from the Indian Ocean

Sthenoteuthis oualaniensis is known for its complex population structure with three major transoceanic forms (viz. middle-sized, dwarf, and giant forms) whose taxonomic status has been disputed for decades. This integrated taxonomic study examines these prevenient morphotypes gathered on cruises in the Indian Ocean to ascertain their status in the evolutionary history of the species. Molecular analyses employing mitochondrial (COI, ND2) and nuclear (H3) markers revealed four genetically distinct and novel lineages of the species in the Indian Ocean, representing three morphotypes from the Arabian Sea and one from the Southern Indian Ocean. The mitochondrial-based phylograms revealed two distinct clades in the species: “dwarf forms + giant form” and “middle-sized forms,” which further branch into geographically structured evolutionary units. Species delimitation analyses recovered five distinct clades, namely, the Arabian Sea giant and dwarf forms, Equatorial, Eastern Typical, and Other Middle-sized forms, representing the consensus molecular operational taxonomic units. H3 being heterozygous could not resolve the phylogeny. Haplotype network and AMOVA analysis of mtDNA genes indicated explicit phylogeographic structuring of haplotypes, whereas these outputs and PCA results were incongruent with the morphological grouping. Phenetic features distinguishing the morphotypes were sometimes plastic and mismatched with the genotypes. The giant form was genetically close to the dwarf forms, contradicting the earlier notion that it descended from the middle-sized form. It may be assumed that the dwarf form evolved following sympatric speciation and adaptation to warm equatorial waters, while the focal features of the Western Arabian Sea guide toward allopatric speciation of the giant form.     

Squid Pen Chitin Chitooligomers as Food Colorants Absorbers

One of the most promising applications of chitosanase is the conversion of chitinous biowaste into bioactive chitooligomers (COS). TKU033 chitosanase was induced from squid pen powder (SPP)-containing Bacillus cereus TKU033 medium and purified by ammonium sulfate precipitation and column chromatography. The enzyme was relatively more thermostable in the presence of the substrate and had an activity of 93% at 50 °C in a pH 5 buffer solution for 60 min. Furthermore, the enzyme used for the COS preparation was also studied. The enzyme products revealed various mixtures of COS that with different degrees of polymerization (DP), ranging from three to nine. In the culture medium, the fermented SPP was recovered, and it displayed a better adsorption rate (up to 96%) for the disperse dyes than the water-soluble food colorants, Allura Red AC (R40) and Tartrazne (Y4). Fourier transform-infrared spectroscopic (FT-IR) analysis proved that the adsorption of the dyes onto fermented SPP was a physical adsorption. Results also showed that fermented SPP was a favorable adsorber and could be employed as low-cost alternative for dye removal in wastewater treatment.     

超声降解法制备可溶性鱿鱼墨黑色素及其抗氧化性

实验研究了一种在碱性条件下利用超声降解制备可溶性鱿鱼墨黑色素的新方法。将鱿鱼墨黑色素溶于NaOH后用超声细胞破碎仪处理1 h,超滤后分别获得不同分子量可溶性黑色素组分。结果显示,超声处理后黑色素平均粒度从17.34 μm下降至1.467 μm,紫外、红外光谱和核磁共振谱图从结构上说明超声作用主要破坏黑色素的高度聚合状态,而黑色素的主要化学结构并没有被破坏,只有少部分基团,尤其是较低分子量组分中的DHI和DHICA结构被氧化;体外抗氧化实验显示经过0.5 mol/L和1 mol/L的NaOH处理,分子量大于10 ku的组分具有很强的抗氧化性,这些组分清除超氧自由基能力(IC₅₀=19～80 μg/mL)远优于作为商品抗氧化剂的肌肽(IC₅₀=355 μg/mL);清除羟基自由基活性(IC₅₀=115～180 μg/mL)与肌肽(IC₅₀=110 μg/mL)相当。可溶性鱿鱼墨黑色素作为一种天然色素和新型自由基清除剂,其良好的可溶性大大提高了机体的吸收利用率。     

北太平洋公海柔鱼渔场浮游植物的生态特征及与环境的关系

利用2010年6~9月北太平洋公海柔鱼(Ommastrephes bartramii)渔场生态环境的调查资料,结合丰度、优势度估算方法以及SUFER应用软件等,对浮游植物的种类组成和数量分布、其与海洋环境因子关系及与中心渔场变动关系等作了探讨分析。结果显示,北太平洋柔鱼渔场的浮游植物经初步鉴定有3门28属80种,种类繁多,组成较复杂,其中东部渔场共39种,暖水性种类为24种,亚寒带冷水性种有7种,热带广布性种有4种,温带偏暖性种有2种,其他生态未命种有2种;而西部的传统渔场共62种,西部渔场鉴定的暖水性种类为43种,亚寒带冷水性种有5种,热带广布性种有9种,温带偏暖性种有3种,其他生态未命种有2种。中东部渔场的浮游植物种类明显少于西部渔场,但亚寒带冷水性种比西部渔场多。采样海域跨度大,包括公海柔鱼的东、西部渔场,范围在150°E~170°W、38°N~45°N的北太平洋公海海域,发现浮游植物丰度在2.98×103~59.87×103 ind/m3范围内,柔鱼的渔获量出现频率高,在14%以上。     

Production and Characterization of Antioxidant Properties of Exopolysaccharide(s) from Peanibacillus mucilaginosus TKU032

Natural polysaccharides have received much attention due to their wide range of applications. Although most microbial exopolysaccharides (EPSs) use sugars as the major carbon source, such as glucose or sucrose, in this study, EPSs were induced from a squid pen powder (SPP)-containing medium by Paenibacillus mucilaginosus TKU032, a bacterial strain isolated from Taiwanese soil. Under the optimal culture conditions, the maximum EPS yield (14.8 g/L) was obtained. MALDI-TOF MS analysis of an EPS fraction purified by gel filtration revealed two mass peaks with molecular weights of ∼1.05 × 10⁴ and ∼1.35 × 10⁴ Da, respectively. The analysis of the hydrolysates of TKU032 EPS with cellulase, pectinase or α-amylase indicated that the glycosidic bond of TKU032 EPS is most likely an α-1,4 glycosidic bond and the hydrolysates are similar to those of starch. In addition, the purified EPS demonstrated strong antioxidant abilities.     

碱液浸提法制备硫酸软骨素的工艺优化

采用碱液浸提法对鱿鱼软骨中硫酸软骨素的提取工艺进行研究。以硫酸软骨素得率为评价指标,通过对影响硫酸软骨素得率的因素进行单因素试验和响应面优化试验确定最佳工艺参数。结果表明,碱液浸提的最佳工艺条件为：料液比1∶8( g/mL)、浸提温度50℃、浸提时间5．3 h, NaOH浓度3%。在此条件下,鱿鱼软骨中硫酸软骨素得率为62．89%。     

Impact of paralarvae and juveniles feeding environment on the neon flying squid (Ommastrephes bartramii) winter–spring cohort stock

In this study, we found that there were significant positive correlations between the catch per unit effort (CPUE, a squid abundance index) for the neon flying squid (Ommastrephes bartramii) winter–spring cohort and the satellite‐derived chlorophyll a concentrations in their spawning grounds located at 140–160°E where 21°C < sea surface temperature < 25°C from February to May. The spawning grounds of the winter–spring cohort are located in a quiet stream region, and a particle tracking experiment, based on the velocity field obtained from an ocean data assimilation system, showed that paralarvae and juveniles aged <90 days remained in their spawning grounds and the chlorophyll a concentration in their habitat had a significant positive correlation with the CPUE. A backward particle tracking experiment also showed that the chlorophyll a concentration in the spawning grounds had a significant positive correlation with the autumn–winter mixed layer depth. Based on these results, we hypothesize that the CPUE interannual variability is caused by variations in the feeding environment of the paralarvae and juveniles, which may be linked to autumn–winter mixed layer depth variations.     

北太平洋海区柔鱼生物学特征分析

本文根据1997年6～11月北太平洋柔鱼生物学特征分析:中部海区渔获胴体组成明显大于西部海区且主要由雌性柔鱼组成;不同月份钓获的雌、雄性柔鱼群体组成有较大的差异;两海区随着生产月份的延续,所渔获的柔鱼胴体范围有扩大的趋势;平均纯体重,雌性柔鱼占平均体重的82.51～84.79％,而雄性柔鱼占平均体重的83.88～85.60％;柔鱼的性腺发育程度随着生产月份的推迟,发育程度也越高,而在相同的月份雄性柔鱼发育程度较雌性柔鱼为高;柔鱼的摄食等级不论是雌鱼还是雄鱼,基本以1、2级为主,较高摄食等级的比例似有逐月下降的趋势;柔鱼的胃含物以鱼的鳞片等鱼的残余物出现率较高,头足类次之,尤其是摄食等级高的胃含物中头足类的比例较高。     

Effect of two extruded diets with different fish and squid meal ratio on growth,digestibility and body composition of Octopus vulgaris (Cuvier, 1797)

The present work studies the growth and body composition of 18 Octopus vulgaris (6 per treatment) fed two extruded diets, namely FMS and 3FMS, based on different fish and squid meal ratios (1:1, and 3:1 respectively). The diets are compared with a control diet based on crab (Carcinus mediterraneus) and bogue (Boops boops). The growing tests were conducted on animals placed in individual 300 L rectangular fibreglass tanks in an open seawater system, containing PVC tubes as shelters, resulting in 100% survival rate. The control group exhibited the highest specific growth rates (SGR = 2.14%BW day^?1), while values of around 0.69%BW day^?1 were achieved by octopuses fed the extruded diets. Even though the three groups of animals showed similar digestive gland indexes, the two extruded diets promoted significant differences in the muscle composition and fatness of the digestive gland. Digestibility of dry matter was not affected by the type of extruded diet, obtaining ADC values of around 88%. The results suggest that squid and fish meal can be both used in dry pelleted extruded diets, with moderate acceptance by the octopus, even though the formulation must be optimized with the aim of improving acceptability and achieve growths in the range of natural diets.