Epibionts on the krill (Euphausia pacifica) from the E coast of Japan

Fernandez‐Leborans, G. 2011. Epibionts on the krill (Euphausia pacifica) from the E coast of Japan. —Acta Zoologica (Stockholm) 00 : 1–10. Specimens of Euphausia pacifica collected from shallow waters of the E coast of Japan showed ciliate epibionts belonging to two suctorian species: Ephelota plana and Gymnodinioides sp. The epibionts were present in a total of 27 anatomical units of E. pacifica, in numbers fluctuating between 8 and 80 individuals per basibiont. Gymnodinioides showed the highest mean number of epibionts. The presence–absence of epibionts indicated some specificity of the species by different locations on the basibiont body, which is corroborated by the analysis of the colonization throughout the longitudinal axis of the basibiont. Ephelota plana was recorded by the first time on E. pacifica, while Gymnodinioides sp. extended its geographical area with respect to previous studies. Morphological, taxonomical features of the species and the statistical analysis of their spatial distribution on E. pacifica are included.     

Preparation and anti-osteoporotic activities in vivo of phosphorylated peptides from Antarctic krill (Euphausia superba)

Antarctic krill (Euphausia superba) protein serves as a novel sustainable protein source for human. Krill protein isolate was phosphorylated by the dry-heating method with sodium pyrophosphate. Phosphorylated peptides from Antarctic krill (PP-AKP) were obtained from phosphorylated protein through tryptic hydrolysis. Two types of phosphate bonds were introduced by phosphorylation, i.e. PO and PO bonds. The anti-osteoporotic activities of PP-AKP at two doses (400 and 800 mg/kg body weight) were investigated with an osteoporotic rat model, which was established with bilateral ovariectomy surgery. Different doses of PP-AKP were given intraperitoneal injections to rats once a day with alendronate as a positive control. Phosphorylated peptides from Antarctic krill dose-dependently preserved bone mineral density in osteoporotic rats by increasing the degree of bone mineralization. Both trabecular and cortical bone strength in osteoporotic rats was significantly improved with PP-AKP treatment. The mechanism by which PP-AKP augmented bone mineral density and bone strength was relation to the reduction in osteoclast-mediated bone remodeling, as was supported by the decrease in bone resorption markers. Phosphorylated peptides from Antarctic krill could be developed as functional food or nutritional supplements.     

2018年夏秋季南设得兰群岛周边水域南极磷虾集群类型及其影响因素

南极磷虾是一种典型的集群性海洋生物,其集群特征为行为生态学研究领域的重要内容之一。南极磷虾在南设得兰群岛周围高度密集分布,然而磷虾集群形状和大小的机制解释仍存在较大的争议。基于南设得兰群岛周边水域收集的Simrad EK80声学数据,本研究利用Echoview V6.16软件,对声学数据进行了分析,并对磷虾集群特征进行了划分。通过主坐标分析(PCoA)检验了环境因素(表温和海况)以及时空因素对各类型磷虾集群产生的影响。结果表明:海况对磷虾集群影响较大,光照强度次之;块状小型集群的时空分布较广,夜间与白天均占有较高比例(>30%);小型集群更易出现在白天,而大型集群则更多出现在深夜; 2月,磷虾集群与海况及纬度显著相关; 3月,集群与时段显著相关; 4月,集群与时段及海况显著相关。     

南极大磷虾粉对卤虫脂肪酸和氨基酸的营养强化作用

以卤虫(Artemia sp.)Ⅱ龄无节幼体作为试验材料,研究0、75、150、225 mg·L-1的南极大磷虾(Euphausia superba)粉对卤虫体内脂肪酸和氨基酸的强化效果,试验共进行18 h,每6h取样检测一次.结果表明:强化组各时段的二十二碳六烯酸、ω3-系列多不饱和脂肪酸总量以及多不饱和脂肪酸总量均显著高于对照组;除了75和225 mg·L-1组6h的二十碳五烯酸与对照组无显著差异外,其他各时段的二十碳五烯酸亦显著高于对照组;75mg·L-1组18h以及150 mg·L-1组12和18h的二十碳四烯酸亦显著升高;150 mg·L-1组的必需氨基酸总量和总氨基酸含量均显著高于对照组,此外,150 mg·L-1组各时间段的必需氨基酸总量/氨基酸总量比值显著高于其他两个强化组和对照组,225 mg·L-1组12 h的必需氨基酸总量/氨基酸总量比值显著高于对照组;南极大磷虾粉对卤虫的脂肪酸和氨基酸均具有较好的营养强化效果,并以150 mg·L-1的强化浓度,12和18 h的强化时间为宜.     

Cadmium‐induced and trans‐generational changes in the cultivable and total seed endophytic community of Arabidopsis thaliana

Trans‐generational adaptation is important to respond rapidly to environmental challenges and increase overall plant fitness. Besides well‐known mechanisms such as epigenetic modifications, vertically transmitted endophytic bacteria might contribute to this process. The cultivable and total endophytic communities of several generations of Arabidopsis thaliana seeds harvested from plants exposed to cadmium (Cd) or not exposed were investigated. The diversity and richness of the seed endophytic community decreased with an increasing number of generations. Aeromicrobium and Pseudonocardia were identified as indicator species in seeds from Cd‐exposed plants, while Rhizobium was abundantly present in both seed types. Remarkably, Rhizobium was the only genus that was consistently detected in seeds of all generations, which suggests that the phenotypic characteristics were more important as selection criteria for which bacteria are transferred to the next plant generation than the actual genera. Production of IAA was an important trait for endophytes from both seed types, while ACC deaminase activity and Cd tolerance were mainly associated with seed endophytes from Cd‐exposed plants. Understanding how different factors influence the seed endophytic community can help us to improve seed quality and plant growth through different biotechnological applications.     

Superbanone,A New 2‐Aryl‐3‐benzofuranone and Other Bioactive Constituents from the Tube Roots of Butea superba

Phytochemical investigation from the tube roots of Butea superba, led to the isolation and identification of a new 2‐aryl‐3‐benzofuranone named superbanone ( 1 ), one benzoin, 2‐hydroxy‐1‐(2‐hydroxy‐4‐methoxyphenyl)‐2‐(4‐methoxyphenyl)ethanone ( 2 ), eight pterocarpans ( 3  –  10 ), and eleven isoflavonoids ( 11  –  21 ). Compound 2 was identified for the first time as a natural product. The structure of the isolated compounds was elucidated using spectroscopic methods, mainly 1D‐ and 2D‐NMR. The isolated compounds and their derivatives were evaluated for α‐glucosidase inhibitory and antimalarial activities. Compounds 3 , 7 , 8 , and 11 showed promising α‐glucosidase inhibitory activity (IC₅₀ = 13.71 ± 0.54, 23.54 ± 0.75, 28.83 ± 1.02, and 12.35 ± 0.36 μm , respectively). Compounds 3 and 11 were twofold less active than the standard drug acarbose (IC₅₀ = 6.54 ± 0.04 μm ). None of the tested compounds was found to be active against Plasmodium falciparum strain 94. On the basis of biological activity results, structure–activity relationships are discussed.     

Protist distribution in the Western Fram Strait in summer 2010 based on 454‐pyrosequencing of 18S rDNA

In this study, we present the first comprehensive analyses of the diversity and distribution of marine protist (micro‐, nano‐, and picoeukaryotes) in the Western Fram Strait, using 454‐pyrosequencing and high‐pressure liquid chromatography (HPLC) at five stations in summer 2010. Three stations (T1; T5; T7) were influenced by Polar Water, characterized by cold water with lower salinity (<33) and different extents of ice concentrations. Atlantic Water influenced the other two stations (T6; T9). While T6 was located in the mixed water zone characterized by cold water with intermediate salinity (~33) and high ice concentrations, T9 was located in warm water with high salinity (~35) and no ice‐coverage at all. General trends in community structure according to prevailing environmental settings, observed with both methods, coincided well. At two stations, T1 and T7, characterized by lower ice concentrations, diatoms (Fragilariopsis sp., Porosira sp., Thalassiosira spp.) dominated the protist community. The third station (T5) was ice‐covered, but has been ice‐free for ~4 weeks prior to sampling. At this station, dinoflagellates (Dinophyceae 1, Woloszynskia sp. and Gyrodinium sp.) were dominant, reflecting a post‐bloom situation. At station T6 and T9, the protist communities consisted mainly of picoeukaryotes, e.g., Micromonas spp. Based on our results, 454‐pyrosequencing has proven to be an adequate tool to provide comprehensive information on the composition of protist communities. Furthermore, this study suggests that a snap‐shot of a few, but well‐chosen samples can provide an overview of community structure patterns and succession in a dynamic marine environment.     

Rapid,economical single‐nucleotide polymorphism and microsatellite discovery based on de novo assembly of a reduced representation genome in a non‐model organism: a case study of Atlantic cod Gadus morhua

By combining next‐generation sequencing technology (454) and reduced representation library (RRL) construction, the rapid and economical isolation of over 25 000 potential single‐nucleotide polymorphisms (SNP) and >6000 putative microsatellite loci from c. 2% of the genome of the non‐model teleost, Atlantic cod Gadus morhua from the Celtic Sea, south of Ireland, was demonstrated. A small‐scale validation of markers indicated that 80% (11 of 14) of SNP loci and 40% (6 of 15) of the microsatellite loci could be amplified and showed variability. The results clearly show that small‐scale next‐generation sequencing of RRL genomes is an economical and rapid approach for simultaneous SNP and microsatellite discovery that is applicable to any species. The low cost and relatively small investment in time allows for positive exploitation of ascertainment bias to design markers applicable to specific populations and study questions.     

Computational determination of refractive index distribution in the crystalline cones of the compound eye of Antarctic krill (Euphausia superba)

In order to understand how a compound eye channels light to the retina and forms an image, one needs to know the refractive index distribution in the crystalline cones. Direct measurements of the refractive indices require sections of fresh, unfixed tissue and the use of an interference microscope, but frequently neither is available. Using the eye of the Antarctic krill Euphausia superba (the main food of baleen whales) we developed a computational method to predict a likely refractive index distribution non-invasively from sections of fixed material without the need of an interference microscope. We used a computer model of the eye and calculated the most realistic spatial distribution of the refractive index gradient in the crystalline cone that would enable the eye to produce a sharp image on the retina. The animals are known to see well and on the basis of our computations we predict that for the eyes of the adult a maximum refractive index of 1.45-1.50 in the centre of the cone yields a better angular sensitivity and light absorption in a target receptor of the retina than if N(max) were 1.55. In juveniles with a narrower spatial separation between dioptric structures and retina, however, an N(max) of 1.50-1.55 gives a superior result. Our method to determine the most likely refractive index distribution in the cone without the need of fresh material and an interference microscope could be useful in the study of other invertebrate eyes that are known to possess good resolving power, but for a variety of reasons are not suitable for or will not permit direct refractive index measurements of their dioptric tissues to be taken.