Freezing resistance in some Antarctic fishes

Measurements of serum freezing points in three Antarctic marine fishes indicated that they do not freeze in the -1.87 degrees C seawater because their blood is isosmotic to seawater. Concentrations of sodium chloride, urea, and free amino acids in the serum accounted for only half of the freezing-point depression of the serum. A protein containing carbohydrate was isolated which accounted for 30 percent of the freezing-point depression of the serum.     

Freezing

There is no first principles theory of freezing or melting, even for the simplest materials. The prediction of phase diagrams is an important first step in understanding the crystal-melt interface, crystallization near equilibrium, and nucleation. Recently, a new approximate theory for the freezing of classical liquids, known as the density functional theory, has been developed. The predictions of the theory are relatively accurate and its mathematical structure is simple enough to provide an attractive starting point for theories of more complex, dynamical phenomena.     

Multiple hemoglobins in fishes

Paper electrophoregrams of the hemoglobins from 14 species of fresh- and salt-water fish demonstrated from one to three components. The relative distribution of these fractions was determined for all species. Mobilities of the three hemoglobins of rainbow trout were calculated from moving-boundary patterns. Low anodal mobility at pH 8.8 was characteristic of many species examined.     

安哥拉山羊胚胎冷冻试验

对安哥拉山羊用总量350IUFSH按递减法处理,配种结束后第6天经子宫手术回收桑椹胚和囊胚供冷冻试验.选用1.4mol/L甘油、1.2mol/L和1.5mol/L乙二醇做防冻保护剂,快速冷冻,-36℃投入液氮保存.采用直接水浴或在空气中停留6～10s使胚胎温度回升,再水浴解冻.胚胎解冻后,用0.5mol/L蔗糖PBSS脱除保护剂,移入2%PBSS中,手术移植于发情后6d的适移受体.结果表明,1.5mol/L乙二醇具有良好的冷冻保护作用.在18～20℃空气中使胚胎温度稍回升,再水浴解冻,可降低胚胎解冻过程中热应激导致的透明带破损,移植于适移受体的妊娠率达45.5%.     

‘寒富’苹果抗寒性研究

为了研究寒富苹果的抗寒能力及其在伊犁河谷适宜栽培的区域,本文以苹果1年生枝条作为试验材料,利用电导法对3种不同品种的苹果休眠枝条在不同低温处理下的电解质渗透率进行测定,并配合Logistic方程确定苹果枝条的低温半致死温度。结果表明：随着处理温度的下降,苹果枝条组织的电解质渗透率变化幅度呈现慢-快-慢的趋势,即“S”形曲线增长。寒富苹果的半致死温度(LT50)在-35℃左右,对照苹果普通富士的半致死温度(LT50)在-29℃左右,黄海棠的半致死温度(LT50)在-38℃左右。结合冻害分级情况,寒富在伊犁州的逆温带可安全越冬,部分平原区也可栽植。     

Freezing tolerance in an adult insect

The adult carabid beetle Pterostichus brevicornis tolerates freezing under natural conditions. Laboratory tests confirm that winter beetles tolerate temperatures below -35 degrees C, whereas summer beetles die if frozen at -6.6 degrees C. Winter beetles can be cooled to about -10 degrees C before freezing, and they thaw near -3.5 degrees C. Summer beetles thaw at -0.7 degrees C. To avoid freezing damage even in winter beetles, cooling rates must be near 20 degrees C per hour or less.     

冻害胁迫下小麦叶片内一些抗冻基因转录水平研究

研究了大田条件下,4个小麦品种幼穗发育不同阶段植株的冻害情况,并比较叶片内谷胱甘肽还原酶(GR)、抗坏血酸过氧化酶(APX)、超氧物歧化酶(SOD)和过氧化氢酶(CAT)等基因的转录水平。结果表明,幼穗发育进程慢的小麦植株受冻害较轻,其叶片内的APX和SOD基因的转录水平较高,与植株的抗冻性表现相一致,表明它们可作为评价小麦抗冻性的鉴定指标;冻害胁迫下,CAT和GR基因的转录水平与小麦植株抗冻性表现不相一致,表明这2个基因可能不适宜作为小麦抗冻性的鉴定指标。     

小鼠半胚冷冻的研究

对半胚冷冻的方法和条件进行了系统研究,证明采用下述程序冷冻小鼠半胚可显著提高解冻半胚的成活率:①在含10％甘油的磷酸缓冲液中平衡35～40min;②在-6.5℃或-7℃诱发结晶,③以0.05℃/min的速度缓慢降温15min;④以0.3℃/min的速度降温至-35℃投入液氮;⑤在30～35℃的水浴中解冻;⑥在含不同浓度(6.6％,3.3％,0％)甘油和0.3mol/L蔗糖的磷酸缓冲液中平衡35～40min,去除甘油。将按上述程序冷冻—解冻的16对半胚移植后,获半胚鼠12只,其中5对为同卵双生。     

油菜寒冻诱抗剂诱导油菜寒冻抗性的研究初报

豫油 5号和陕油 6号经寒冻诱抗剂处理后 ,在 4℃和 - 4℃条件下 ,体内可溶性糖、脯氨酸、甜菜碱含量明显高于未经处理的对照组 ;处理组叶绿素荧光参数 (F0 )低于对照组 ,PSII光化学效率 (Fv/Fm)高于对照组。结果表明 ,处理组的抗寒冻性明显高于对照组。     

鱼类类胡萝卜素着色研究进展

类胡萝卜素(carotenoid)是影响鱼类体色特性的主要色素,但鱼类自身不能合成这一色素,因此必须从食物中摄入。鱼类类胡萝卜素着色过程涉及对类胡萝卜素的代谢与沉积过程,色素细胞的分化和空间排列,以及与其他色素和色素细胞间的相互作用,这一过程非常复杂,但我们对其机理知之甚少。综述了类胡萝卜素着色效果与鱼类遗传特性、生理状态以及环境因素之间的相关关系,对该研究领域发展趋势进行了讨论和展望,期望为我国研究鱼类体色的形成机制提供一些新的信息。     

鱼类的变态发育及其适应意义

综述了不同纲目一些代表鱼类的变态发育现象,变态发育对环境的适应,以及鱼类变态发育的特点,并对变态发育研究中存在的问题进行了讨论。     

柑桔冻害的数量化回归分析

在柑桔主要产区桔树遭受严重害的年份，对构成立地，树体珠栽培措施的２０多个因子，设置了９０个标准地进行了详细调查，应用数量化回归分析诸因子与柑桔冻害之间的关系。结果表明：１９９１年，影响柑桔冻害达极显著瓣是土层厚度，土壤质地，基肥，追肥和病虫害；达显著水平的是土壤肥力，坡向，树龄，根深和结果量。