黑河林区驼鹿冬季食性研究

1987—1988年在黑龙江省黑河林区,应用粪便显微组织学分析技术,结合野外啃食调查,对驼鹿冬季食物组成、食物选择性和利用率进行了研究。结果表明,冬季驼鹿共采食31种(属)植物,其中柳、榛、桦、红松、杨和紫椴是主要的冬季食物(19.9％、18.0％、16.7％、14.9％、7.3％和6.7％)。驼鹿对杨、柳、红松和紫椴有正选择性,对榛、桦和毛赤杨有负选择性。选择性的强弱顺序为:杨>柳>红松>紫椴>榛>桦>毛赤杨。驼鹿对柳的选用率最高(32.1％),对桦的利用率最低(12.1％)。     

大仓鼠肥满度的研究

本文依公式K=100W/L~3计算了大仓鼠肥满度。统计结果表明,雌性肥满度大于雄性肥满度。肥满度随年龄增长而减小。不同作物类型样地中大仓鼠的肥满度变化不明显。不同季节肥满度有一定的变化,主要与繁殖和气候有关。肥满度与种群密度之间不存在明显的对应关系。     

产胞外邻苯二酚1.2—双加氧酶的菌种筛选和发酵条件的研究

Two strains of Pseudomonus sp. having the extracellular catechol 1, 2-dioxygenase activity were selected from 112 bacterial strains. The conditions for enzyme production of the strains were examined. The optimal temperature and pH for enzyme formation were 30 degrees C and pH 6.8-7.0 respectively. Enzyme formation was enhanced by sodium benzoate, and was markedly inhibited by glucose, maltose and glycerol. Ammoniacal nitrogen sources were essential for cell growth and enzyme production. Sodium succinate was an effective inducer for enzyme formation. When the organism was grown in 0.15% sodium benzoate medium (pH 6.8-7.0) at 30 degrees C for 72 hours, about 10 units of catechol 1,2 dioxygenase per ml was obtained.     

根霉超氧化物歧化酶同工酶类型的鉴别

利用ＫＣＮ、Ｈ_２Ｏ２和ＳＤＳ的选择性反应引起的ＳＯＤ同工酶谱带变化即可鉴别粗抽提液中的ＳＯＤ同工酶类型;用这种方法对五株不同种根霉的鉴别实验表明,它们均不同程度地含有Ｃｕ,Ｚｎ型和Ｍｎ型两种ＳＯＤ,前者约占８０％左右,后者只占２０％左右。用邻苯三酚自氧化法对样品中ＳＯＤ活性测定结果与在同工酶谱上的鉴别结果基本一致。     

Microbial nitrogen and phosphorus co-limitation across permafrost region

The status of plant and microbial nutrient limitation have profound impacts on ecosystem carbon cycle in permafrost areas, which store large amounts of carbon and experience pronounced climatic warming. Despite the long-term standing paradigm assumes that cold ecosystems primarily have nitrogen deficiency, large-scale empirical tests of microbial nutrient limitation are lacking. Here we assessed the potential microbial nutrient limitation across the Tibetan alpine permafrost region, using the combination of enzymatic and elemental stoichiometry, genes abundance and fertilization method. In contrast with the traditional view, the four independent approaches congruently detected widespread microbial nitrogen and phosphorus co-limitation in both the surface soil and deep permafrost deposits, with stronger limitation in the topsoil. Further analysis revealed that soil resources stoichiometry and microbial community composition were the two best predictors of the magnitude of microbial nutrient limitation. High ratio of available soil carbon to nutrient and low fungal/bacterial ratio corresponded to strong microbial nutrient limitation. These findings suggest that warming-induced enhancement in soil nutrient availability could stimulate microbial activity, and probably amplify soil carbon losses from permafrost areas.     

基于环境DNA技术的赤水河秋季鱼类多样性分布特征

赤水河是长江上游少有的仍保持自然流态的大型一级支流,是长江鱼类重要的繁衍场和珍稀物种的保护地,摸清其鱼类多样性现状及鱼类群落结构特征对赤水河水生态恢复评估极为重要。于2021年9月对赤水河流域开展了鱼类多样性、分布及其特征调查,全流域共设置52个采样点,采用环境DNA技术采集并研究了赤水河鱼类的组成及其分布。结果显示通过环境DNA方法共调查到鱼类6目18科62属77种,包含16种长江特有鱼类。以鲤形目为主,占总数的87.87%。赤水河鱼类食性以杂食性和肉食性鱼类为主,群落结构上,处于下层水环境鱼类较多;赤水河鱼类优势种为宽鳍鱲(Y=0.205)、西昌华吸鳅(Y=0.085)、麦穗鱼(Y=0.068)、乌苏拟鲿(Y=0.033)、云南光唇鱼(Y=0.027);赤水河上游和下游鱼类群落(P<0.01)和Shannon-Wiener指数差异均显著(P<0.05)。海拔、流速、pH、电导率和温度是影响赤水河鱼类多样性的主要环境因素。为环境DNA技术在赤水河鱼类多样性调查中的应用提供了探索性研究,将有助于赤水河生物多样性的保护。     

在无溶剂系统中固定化脂肪酶合成聚乙二醇400月桂酸酯

在无溶荆反应系统中,研究了固定化假丝酵母(Candida sp)-1619脂肪酶催化合成聚乙二醇400(PEG400)月桂酸酯的酯化条件。在反应过程中不断脱水和使月桂酸的量高于化学计量值的方法,使酯化率明显提高。分批补加PEG₄₀₀使产量进一步增加。在5．0mmol月桂酸．2．5mmolPEG400,20mg同定化脂肪酶(200u),O．2ml水组成的反应体系中,40℃,锥形瓶敞口振荡反应48h。醑化率达91％;在负压条件下反应．酯化率达98．9％;反应体系中月桂酸的董增加到6．0mmol时,PEG₄₀₀完全被酯化。用己烷提取产物的收率为95％．通过薄层色谱鉴定酯化产物为双酯。     

高必需氨基酸转基因马铃薯的研究

８０年代以来,马铃薯遗传转化系统日趋成熟,转基因工程植株已被广泛应用于基础科学研究［１］。作为食物蛋白和能量主要来源的马铃薯,提高其蛋白质含量及质量的遗传工程研究正受到人们的普遍关注［２］。Ｙａｎｇ等［２］将旨在改善氨基酸平衡的ＣＡＴ－ＨＥＡＡＥ（氯酶素乙酰转移酶－高含量人体必需氨基酸）融合基因导入马铃薯,获得了Ｓｏｕｔｈｅｒｎｂｌｏｔ、Ｎｏｒｔｈｅｒｎｂｌｏｔ、Ｗｅｓｔｅｒｎｂｌｏｔ的证据,但尚缺少氨基酸分析的资料。玉米醇溶蛋白（ｚｅｉｎ）［３］是一个富含甲硫氨酸的贮存蛋白,它和人工合成的ＨＥ…     

Generation of formic acid and ethanolamine from serine in biosynthesis of linear gramicidin by a cell-free preparation of Bacillusbrevis (ATCC 8185)

A growing organism that produces antibiotic peptide was incubated with L-(U-¹⁴C)serine for labeling linear gramicidin. Linear gramicidin was isolated by a simple chromatographic method from tyrothricin (mixture of linear gramicidin and tyrocidine) applied to a column of basic aluminum oxide. The hydrolysate of labeled linear gramicidin on thin layer chromatography showed that L-(U-¹⁴C)serine was one of a precursor of ethanolamine moiety by autoradiography. L-(3-¹⁴C)serine generated formic acid in the presence of tetrahydrofolic acid by an enzyme fraction prepared with ammonium sulfate, and further formed ethanolamine binding to the protein. Formylvaline was biosynthesized by it with tetrahydrofolic acid and ATP, and subsequently released from the protein.     

Maturation and fertilization of porcine oocytes in vitro

Four experiments were conducted to study 1) factors affecting porcine oocyte maturation in culture medium and 2) a new method for oocyte maturation outside the porcine body. In Experiment 1, five groups of oocytes were cultured in m-TCM199 or m-KRB medium for 24 to 28, 32 to 36 or 40 to 42 hours and then were fertilized in vitro. The cleavage rate (two to four-cell stage) of oocytes cultured for 32 to 36 hours was significantly higher than those of the other oocytes. The results indicate that a suitable culture period for the in vitro maturation of porcine oocytes is 32 to 36 hours. In Experiment 2, four groups of oocytes were cultured in m-KRB or m-KRB supplemented with PFF, PMSG or FSH for in vitro maturation, and the cleavage rates of oocytes were 7.94, 22.56, 30.23 and 23.26%, respectively, after in vitro fertilization. The results show that porcine follicular fluid (PFF) and gonadotrophins added to the culture medium promote porcine oocyte maturation in vitro. In Experiment 3, oocytes were cultured in m-KRB or m-TCM199, supplemented with both gonadotrophin and pocine folliclar fluid for maturation in vitro. After fertilization in vitro, the cleavage rates of oocytes were 26.32 and 27.93% for the two media. The results indicate that the difference between m-KRB and m-TCM199 was insignificant when the media were used to culture porcine oocytes. But there was a significant difference when PFF and gonadotrophins were added to the basic media. In Experiment 4, porcine oocytes were transferred into the reproductive tracts of other animals for maturation. After 34 to 36 hours, the oocytes were collected and fertilized in vitro. The cleavage rates of oocytes were 10.42, 28.45, 3.33 and 36.36%, respectively, for the oocytes matured in mouse uterine horns, rat uterine horns, rat oviducts or rabbit oviducts. The results show that porcine oocytes can be matured in the reproductive tracts of other animals.