246 resultados para chilling injure


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大豆是重要的油料和蛋白植物。在生产实践中,在播种后达到早苗和齐苗是大豆丰收的前提。种子的吸胀冷害是农业生产的严重问题。吸胀冷害发生在种子开始吸水萌动的萌发初始阶段。吸胀冷害不仅发生在高寒地带和低温冷湿地区,尤其在我国东北地区,造成我国乃至全球大豆不同程度的减产。吸胀冷害的原初作用位点在生物膜上,本实验从呼吸代谢的角度研究吸胀冷害对种子活力的影响,探讨吸胀冷害的机制。 本实验选用由黑龙江省黑河农业科学院提供的对低温中度敏感的黑河13 号大豆种子为材料,分别经22°C、10°C 和4°C 恒温培养箱24 h 后,测定其生理指标,通过透射电镜观察细胞超微结构,利用蛋白质组技术研究低温吸胀与种子呼吸代谢的关系,得到的结果如下: 低温吸胀阻碍胚轴膜系统的修复。通过电解质渗漏率测定发现,4°C 到22°C 温度范围内,提高吸胀温度有助于保持细胞膜的完整性,显著降低吸胀后胚轴电解质渗漏。在低温下吸胀,胚轴活性氧清除酶的活性受到抑制,活性氧含量增加,增强了膜脂过氧化作用,进而导致种子活力下降。 通过透射电子显微镜观察,大豆种子在22°C 吸胀24 h 后,胚轴细胞液泡明显变大,在细胞中所占比例很高,并且细胞内膜系统比较发达,能清晰观察到细胞核,线粒体,质膜,内质网整齐有序的形状。胚轴的细胞含有其它结构正常的细胞器,包括细胞壁,胞间连丝,淀粉粒和油体等。线粒体的外膜、内膜、嵴发育较完善。10°C 和4°C 的吸胀严重损伤了胚轴中细胞器的修复,细胞膜不规则,没有发现内质网和胞间连丝,线粒体的体积较小以及膜系统不发达,尤其是4°C 吸胀的胚轴中细胞器的损伤更加严重,细胞膜系统紊乱。 低温吸胀抑制了线粒体从轻线粒体向重线粒体的修复,以及线粒体的耗氧能力。22°C 吸胀的线粒体的总体耗氧能力较高,电子传递主要是利用复合体I 的电子传递途径。10°C 吸胀的线粒体总体耗氧呼吸较低,且其线粒体的电子传递主要以复合体II 的途径。4°C 吸胀的线粒体的耗氧能力则更低。 将分离得到的线粒体进行的蛋白质组分析,共分离400 多个蛋白点,其中有20 个点有表达差异。经ESI-Q-TOF-MS/MS 鉴定,六个下调的蛋白质分别为ATP 合成酶的亚基 (线粒体的氧化磷酸化),线粒体延长因子Tu(线粒体基因组转录), 苹果酸脱氢酶(三羧酸循环),精氨酸酶(尿素循环)和2 个线粒体chaperonin-60 (热稳定蛋白)。这些蛋白在低温吸胀时下调表达,影响了线粒体的正常生理代谢,说明它们在维持线粒体正常代谢中起到了重要的作用。 综上所述,低温吸胀影响了线粒体的结构和生理功能的修复,减少了能量和中间物质供应给种子萌发,造成了种子活力的下降。

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Swordfish are kept chilled, not frozen, for up to 15 days before being unloaded at Australian ports. Swordfish landed alive, and to a lesser extent prerigor, have better quality when unloaded. Warmer fishing waters did not lead to poorer quality at unloading. There was a serious loss of quality during long fishing trips. Sex had no influence on swordfish quality. Three methods of chilling were evaluated: refrigerated seawater (RSW) chilling for up to 2 days followed by storage under ice, refrigerated brine (seawater with extra salt added) for up to 2 days followed by storage in a freshwater ice slurry, and ice slurry (freshwater ice mixed with seawater) for up to 2 days followed by storage under ice only. Two fishing trips were monitored for each method. The freshness indicator K value was used to determine which method produced the best quality swordfish when unloaded at the factory. Storage method played a larger role in quality loss than capture conditions. Refrigerated brine produced the best quality swordfish when the machinery functioned properly closely followed by RSW. Ice slurry chilling of large fish such as swordfish exhibited initial delays in the reduction of core temperature which led to lower quality. This method could be improved with the addition of mechanical circulation. Mechanical problems, which resulted in minor increases of temperature during brine storage, led to a much larger loss of quality than would be expected.

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Experiments were conducted to study the effect of time of digging and nursery-growing environment on the levels of non-structural carbohydrates in 'Festival' strawberry transplants (Fragaria xananassa) over 2 years in southeastern Queensland, Australia. We were interested in determining whether there was a strong relationship between the potential productivity of this material and reserves in the plants. First, bare-rooted plants were obtained from Stanthorpe in southern Queensland from early March to mid-April/late April. Second, bare-rooted plants were sourced from Stanthorpe (a warm-growing area) or from Toolangi in Victoria (a cool-growing area). In Year 1 of the experiments, the nursery material from the different treatments was grown at Nambour in southeastern Queensland and fruit yield determined. The total weight of nonstructural carbohydrates/plant increased as digging was delayed and was higher in the plants from Stanthorpe than the plants from Toolangi. Plants dug on 17 Mar. in Year 1 had higher weights of non-structural carbohydrates [292 mg/plant dry weight (DW)] than plants dug on 3 Mar. (224 mg/plant) and higher early yield to the end of June or to the end of July and higher total yield to mid-October adjusted by the length of the growing season for the different treatments. Plants dug on 1 Apr. (408 mg/plant) or on 13 Apr. (445 mg/plant) had higher reserves than the plants dug on 17 Mar. but lower yields. Only the differences in yields between the plants dug on 3 Mar. and 17 Mar. reflected the differences in carbohydrates. The stock from Stanthorpe had greater reserves (408 mg/plant) than the stock from Toolangi (306 mg/plant) but similar yields in Year 1 possibly because of poorer flowering in the nursery plants. It was concluded that carbohydrate reserves in transplants only partially reflect their productivity in this environment.