Controlling preharvest maturity in farmed Arctic char: A review from the Canadian perspective

Arctic char, Salvelinus alpinus L. is a promising candidate for aquaculture expansion in Northern Europe, Canada, and the United States because of its excellent growth at low temperature, tolerance to high rearing density, high fillet yield, and superior flesh texture and flavor. To support this industry, several breeding programs in these regions currently focus on selection for growth and delayed maturation. While the growth potential of existing strains has been improved, preharvest sexual maturation remains a problem in this industry. This article describes current knowledge on the control of preharvest maturation in Arctic char at the hatchery level through the production of single‐sex and triploid populations and during the grow‐out phase through the manipulation of photoperiod and feed intake. Research perspectives on the subject are also suggested in order to complement the efforts of ongoing breeding programs.     

Dietary Phosphorus Requirement of Fingerling Indian Major Carp,Labeo rohita (Hamilton)

Dietary phosphorus requirement of fingerling Labeo rohita (6.1 ± 0.13 cm; 1.88 ± 0.05 g) was quantified by feeding seven isonitrogenous (350 g/kg crude protein) and isocaloric (16.72 kJ/g gross energy) purified diets with different levels of phosphorus as 3.5 (basal diet), 4.6, 5.7, 6.5, 7.8, 8.9, and 10.1 g/kg. Triplicate groups of fish were fed at 0800, 1200, and 1600 h to apparent satiation for 8 wk. Live weight gain (LWG; 494.68%), specific growth rate (3.18%/d), feed conversion ratio (1.54), feed efficiency (0.65), protein gain (PG; 1.26 g/fish), protein efficiency ratio (1.86), and phosphorus utilization efficiency (98.78%) improved significantly (P < 0.05), with increasing dietary phosphorus level up to 6.5 g/kg. However, phosphorus contents of vertebrae and scale increased significantly up to 7.8 g/kg. Dietary phosphorus levels significantly affected serum phosphorus concentration and alkaline phosphatase activity. Broken‐line analysis based on LWG; PG; and whole‐body, vertebrae, and scale phosphorus against dietary phosphorus indicated the optimal phosphorus requirement of fingerling L. rohita at 6.56, 6.58, 6.56, 8.02, and 8.44 g/kg diet, respectively. In order to restrict superfluous phosphorus in the diet, inclusion of 6.56 g/kg phosphorus is recommended for optimal growth of fingerling L. rohita.     

BMP-2和p38MAPK在小鼠骨髓间充质干细胞向成骨细胞分化中的作用

目的观察骨成型蛋白（BMP）-2和p38丝裂原激活蛋白激酶（MAPK）在小鼠骨髓间充质干细胞（BMSC）向成骨细胞分化中的作用。方法体外分离和扩增小鼠BMSC,分为对照组、BMP-2组及阻断剂组,其中BMP-2组加入BMP-2,阻断剂组加入SB203580（p38MAPK通路阻断剂）和BMP-2。测定碱性磷酸酶（ALP）活性、钙沉积量、p38MAPK表达。结果与对照组相比,BMP-2组BMSC中ALP活性和钙沉积量增加（P〈0.01）,p38MAPK表达较早出现。阻断剂组p38MAPK表达明显延迟,与对照组相似。结论 BMP-2可通过p38MAPK通路促进BMSC向成骨细胞分化。     

生长因子对兔骨髓间充质干细胞增殖的影响

旨在研究碱性成纤维细胞生长因子(bFGF)对兔骨髓间充质干细胞(BMSCs)体外生长及增殖的影响。体外培养并鉴定兔BMSCs,用不同浓度的bFGF(5、10、20、40、80和100μg.L-1)作用于兔BMSCs,用四甲基偶氮唑盐比色法(MTT)、流式细胞仪观察细胞的生长及增殖情况。结果,经免疫细胞化学法和分化反推法鉴定所分离培养的细胞为兔骨髓间充质干细胞;MTT法结果显示,bFGF浓度为80μg.L-1时细胞的增殖能力最强(P<0.01),在培养第3天即出现显著的促增殖作用(P<0.01);流式细胞仪结果显示,bFGF组BMSCs的增殖指数明显高于对照组(P<0.01)。说明bFGF有促进体外培养兔BMSCs增殖的作用,浓度为80μg.L-1时促增殖能力最强,可以作为体外扩增培养兔骨髓间充质干细胞的最佳培养条件。     

Dysfunction of proteasome inhibits the proliferation of hBMSCs via activation of P53

AIM: To investigate the role of P53 in decreased cell proliferation and proteasomal activity during culture expansion of human bone marrow mesenchymal stem cells (hBMSCs). METHODS: The proteasomal activity and expression level of P53 in early-passage (passage 3~4) and late-passage (passage≥14) hBMSCs were observed. Early-passage hBMSCs were divided into DMSO control group, MG132 group (treated with 10 μmol/L MG132 for 4 h) and pifithrin-α(PET-α) + MG132 group (pretreatment with 20 μmol/L PFT-α for 1 h then exposure to MG132 for 4 h). The proliferation and cell cycle distribution of the cells were measured by BrdU incorporation assay and PI staining. To further confirm the effect of P53 inhibitor on late-passage hBMSCs, the cells were incubated with 20 μmol/L PFT-α and the BrdU-positive cells were counted. RESULTS: Accompanied by reduced proteasomal activity, the expression level of P53 in late-passage hBMSCs was up-regulated by 16.89%±4.44% compared with early-passage cells. Application of the proteasome inhibitor MG132 reduced the proliferation of early-passage hBMSCs, and the percentage of BrdU-positive cells dropped to 33.36%±2.24%. However, MG132-induced decrease in cell proliferation was partially reversed by pretreatment with PFT-α. BrdU-positive cells in PFT-α + MG132 group were increased to 49.23%±2.67%. The cell cycle distribution had no significant difference between PFT-α + MG132 group and DMSO group, and the higher proliferation index was found in PFT-α + MG132 group but not in MG132 group. Inhibition of P53 activity in late-passage hBMSCs by PFT-α promoted the cell proliferation, and the percentage of BrdU-positive cells was higher than that in control group. CONCLUSION: Long-term expansion of hBMSCs in vitro reduces proteasomal activity, which in turn activates P53 to suppress cell proliferation through blocking cell cycle progression.     

唇䱻twist1和twist2基因克隆及其在肌间刺骨化过程中的表达

在脊椎动物中存在着2种twist基因,即twist1和twist2,二者对骨骼的发育具有调控作用。为探究唇?twist1和twist2与肌间刺骨化的相关性,实验克隆得到了唇?twist1和twist2基因cDNA序列。氨基酸序列比对结果显示,唇?TWIST1和TWIST2与其他鱼类保守性较高,都具有螺旋-环-螺旋(HLH)结构域和色氨酸-精氨酸(WR)结构域。系统进化树分析表明,唇?TWIST1和TWIST2与斑马鱼亲缘关系最为接近。通过荧光定量PCR检测发现唇?twist1和twist2基因在所有被检测的组织中均有表达,twist1在脑中的表达量最高,心脏中次之,在脾脏中表达量最低。twist2在皮肤和鳃中的表达量较高,在脾脏中的表达量最低。此外,twist1和twist2基因的表达量在肌间刺骨化的4个关键阶段发生显著变化。研究表明,twist基因与肌间刺骨化有一定的相关性。本研究首次在经济鱼类中克隆得到了twist基因,并揭示了twist基因与肌间刺骨化的相关性。研究结果将为进一步调查鱼类twist基因功能以及肌间刺形成的分子机制提供基础数据。     

Profiles of Fatty Acids in Different Bone Structures of Growing Chicks

This study was concerned with the dynamics of fatty acids in tissues involved in the growth and mineralization of the femur of Starbro chicks from 1 to 50 days of age. Four chickens that died of suffocation were obtained each day. Altogether, 400 femoral bones were studied in five age groups (I–V). Compact bone, spongy bone and articular cartilage were sampled. Lipids were extracted according to Folch and fatty acids were separated using gas chromatography. The fatty acid profile was found to change with age. Fatty acids with the highest content in bone were C_18:1, C_16:0, C_18:2 and C_18:0. The highest content of fatty acids was found in spongy bone and the lowest in articular cartilage. Several correlations were revealed between individual fatty acids. The following conclusions were drawn. (1) Fatty acid profiles in compact bone, spongy bone and articular cartilage change with age of chicks. (2) Oleic (C_18:1), palmitic (C_16:0), linoleic (C_18:2), stearic (C_18:0) and arachidonic (C_20:4) acids accounted for most of the fatty acid pool. (3) Correlations in the content of fatty acids were noted between bone structures.     

Unbalanced nutrient ratios in pelleted compound recycling fertilizers

The aim of this study was to contribute to the development of pelleted compound recycling fertilizers with favourable handling and spreading characteristics and balanced nutrient ratios by combining nitrogen (N)‐ and phosphorus (P)‐rich waste resources (meat bone meal, fish sludge or food waste) with potassium (K)‐rich bottom wood ash. Pelleted compound recycling fertilizers with good durability and low dusting tendency were produced by roll‐pelleting preheated waste resources at a suitable moisture content. However, the nutrient ratios in the final products were insufficiently balanced, with too low N concentrations relative to P and K to meet crop demands. In a bioassay using barley (Hordeum vulgare ) and a nutrient‐deficient sand/peat mixture, the relative agronomic effectiveness (RAE ) of pelleted compound recycling fertilizers and reference recycling fertilizers was 22–42% of that of mineral compound fertilizer. Growth limitation was due to reduced N availability (mineral fertilizer equivalent ‐ MFE = 35–57%) or reduced P availability (MFE  = 20–115%), with the greatest P fertilizer value obtained for digestate based on dairy manure and fish sludge. Availability of K in bottom wood ash was masked by the experimental soil.