The development of oocyte cryopreservation techniques in blue mussels Mytilus galloprovincialis

Reliable techniques for the cryopreservation of both sperm and oocytes of the blue mussel Mytilus galloprovincialis Lamarck would increase the availability of seed supplies out-of-season and enhance efficiency in selective breeding. We have investigated the optimal cryo-technique for blue mussel oocytes. The toxicity of three cryoprotective agents (CPAs) [dimethyl sulfoxide (DMSO), ethylene glycol (EG) and propylene glycol (PG)] at different concentrations (1–5 M) and exposure times (0.25–30 min) were investigated for mussel oocytes at room temperature (20 °C) or on ice. The same CPAs (1, 1.5 and 2 M) as well as three different cryoprotectant mixtures [1.5 M EG + 0.2 M trehalose + 100 % Milli-Q water (EGTM); 1.5 M EG + 0.2 M trehalose + 75 % Milli-Q water + 25 % seawater; 1.5 M EG + 0.2 M sucrose + 100 % Milli-Q water] were tested by comparing the post-thaw oocyte fertilization rate after using the slow-cooling method. Vitrification was also examined; however, this method failed to produce any post-thaw surviving oocytes. Among the tested CPAs, EG was the least toxic to oocytes. There was a tendency for the equilibration of CPAs on ice to achieve a higher oocyte fertilization rate compared with that at room temperature, and this difference was significant at concentrations of 3 and 4 M (P < 0.01). The DMSO, EG and PG treatments all resulted in post-thaw fertilization, with EGTM achieving the highest number of surviving oocytes (32 %). At the optimal seeding temperature (?7 °C), the addition of 0.2 M trehalose to EG resulted in a better fertilization rate of post-thawed oocytes than the addition of 0.2 M sucrose. All of the treatments evaluated produced D-larvae from post-thawed oocytes, although the rates were low.     

Spatial patterns of recreational exploitation in eastern Australian ROFAs: implications for zonal management

Effective management of recreational fisheries requires information on fine‐scale spatial patterns of recreational exploitation. Such information is particularly important for specially designated regions such as recreational‐only fishing areas (ROFAs). Using data acquired through progressive counts and interview‐based surveys, this study quantitatively compared recreational effort, harvest‐per‐unit‐effort (HPUE) and species composition among zonal habitats in three representative estuarine ROFAs in eastern Australia. The zones compared were as follows: (1) entrance channels; (2) lake areas; (3) artificial reefs; (4) tributary creeks; (5) rivers; and (6) canals. In most cases, effort was concentrated in the lake zones, which had the greatest access to fisheries resources. The lake and channel zones were associated with some of the highest HPUEs for key taxa [Acanthopagrus spp. (hybrid complex of Acanthopagrus butcheri (Munro) × Acanthopagrus australis (Owen)), Platycephalus fuscus (Cuvier), Sillago ciliata (Cuvier) and Girella tricuspidata (Quoy & Gaimard)] and a greater number of highly sought‐after species. Drawing on specific examples from these findings, this paper concludes by illustrating how spatial information on exploitation gained from this type of research can be used to meet the fundamental goals of recreational fisheries management at fine spatial scales.     

木薯产品营养成分的分析与比较研究

本试验对3种木薯产品及玉米对照样品的主要营养成分包括粗蛋白质、粗脂肪、粗纤维、粗灰分、无氮浸出物、总淀粉、支链淀粉、直链淀粉、氨基酸、非淀粉多糖、矿物质的含量及其体外干物质和淀粉消化率、淀粉颗粒特征等指标进行了比较研究。结果表明,与玉米对照相比,木薯产品粗蛋白质和氨基酸含量较低,蛋白质品质低劣;木薯粒粗脂肪、粗纤维、粗灰分含量均显著高于玉米（P<0.05）;木薯渣无氮浸出物含量显著低于木薯干（P<0.05）,而粗灰分和粗纤维含量均显著高于木薯干和玉米（P<0.05）;木薯干和木薯粒的总淀粉含量与玉米相当,但直链淀粉/支链淀粉比值显著低于玉米（P<0.05）,木薯渣中抗性淀粉含量显著高于其他木薯产品和玉米对照（P<0.05）,玉米淀粉粒形态为不规则多面体,而木薯淀粉粒形态似球形;木薯产品中钙、钾、铁和锰的含量均显著高于玉米（P<0.05）,而磷和锌的含量均显著低于玉米（P<0.05）;玉米中可溶性非淀粉多糖（SNSP）含量显著低于3种木薯产品,且木薯渣中SNSP含量显著高于木薯干和木薯粒（P<0.05）;木薯渣中不溶性非淀粉多糖含量显著高于木薯干和木薯粒（P<0.05）,且其不溶性半乳糖的含量显著高于其他木薯产品及玉米（P<0.05）;木薯粒干物质和淀粉消化率均显著高于木薯干、木薯渣和玉米（P<0.05）,木薯渣干物质和淀粉消化率均显著低于玉米和木薯干（P<0.05）。本研究结果对木薯产品在饲料中的应用有一定的指导意义。     

High frequency, cell type-specific visualization of fluorescent-tagged genomic sites in interphase and mitotic cells of living Arabidopsis plants

Background  

Interphase chromosome organization and dynamics can be studied in living cells using fluorescent tagging techniques that exploit bacterial operator/repressor systems and auto-fluorescent proteins. A nuclear-localized Repressor Protein-Fluorescent Protein (RP-FP) fusion protein binds to operator repeats integrated as transgene arrays at defined locations in the genome. Under a fluorescence microscope, the tagged sites appear as bright fluorescent dots in living cells. This technique has been used successfully in plants, but is often hampered by low expression of genes encoding RP-FP fusion proteins, perhaps owing to one or more gene silencing mechanisms that are prevalent in plant cells.     

Neuroendocrine,Metabolic and Genomic Cues Signalling the Onset of Puberty in Females

Puberty is the result of a dynamic interaction between genetic factors and environmental cues, all of which lead to the attainment of reproductive capacity. Thus, significant changes in hormone secretion occur from the pre‐pubertal to the pubertal stage. The objective of this review is to provide an update of some endocrine, physiological, metabolic and genetic concepts involved in the establishment of the hypothalamic‐hypophyseal‐gonadal axis function promoting the onset of the reproductive function during puberty. To achieve this purpose, basic aspects of the function of the hypothalamic‐hypophyseal‐gonadal axis, the control of the axis by neurotransmitters and the interaction between reproductive function and metabolic status will be considered. Finally, the role of the novel kisspeptin system and the GPR54 receptor as modulators of puberty will be considered, in addition to the hierarchical expression of the main genes acting as regulators of the onset of puberty.     

Contrasting impact of whole-tree-harvesting on chemical quality of plant foliage in coastal versus inland forest

Whole-tree-harvesting (WTH) is gaining support as a means to obtain more bioenergy from forests. One aspect that is scarcely addressed is its impact on the chemical quality of post-harvest plant growth, which may initiate ecological cascade effects through, for example, altered patterns of herbivory and decomposition. We measured C:N ratios and phenolic compounds in foliage from birch Betula spp. that had grown naturally after WTH and conventional harvest (CH) on two boreal sites in inland and more coastal Norway, three or five years after harvest. We found that carbon concentrations were higher after WTH compared to CH on the near-coastal site in spring and summer, but not on the inland site. The only observed change in nitrogen concentration after WTH was that it was lower compared to CH on the near-coastal site in autumn. In line with these changes, the C:N ratio was higher with WTH throughout the season on the near-coastal site, ostensibly favouring production or accumulation of plant defence metabolites. Expectedly, we observed altered concentrations of several phenolic compounds with WTH, particularly at the near-coastal site. Further studies are needed to clarify patterns, but our data strongly suggest that sustainability assessments of WTH should not ignore impact on plant chemical quality, and its potential consequences for trophic interactions.     

Variation and population structure at microsatellite and isozyme loci in wild cabbage ( Brassica oleracea L.) in Dorset (UK)

We examined variation at four isozyme and seven microsatellite loci in natural populations of Brassica oleracea L. on the coast of Dorset. All loci were polymorphic, and the diversity index of isozyme loci was similar to that of the microsatellites. Both microsatellites and isozymes showed significant spatial differentiation of genetic variation, but the scale differed between the marker types. Significant non-random mating at isozyme loci was detected within small groups of about five plants, in which adjacent individuals were separated by less than 5 m. On the other hand, non-random mating at microsatellite loci was only detected within the Dorset region as a whole. F_ST was significant for all loci and there was evidence of isolation by distance at both microsatellite and isozyme loci. From these data we infer that there is low but significant amounts of gene flow among B. oleracea populations in Dorset. The differences in the genetic structure between the two types of marker may be due to higher mutation rates at the microsatellite loci; however, the data suggest that stepwise gain or loss of single repeat units is not the principal mechanism.