陆地生态系统碳平衡主要研究方法评述

陆地生态系统碳平衡是全球变化科学中的核心问题之一,目前也是生态科学中的前沿与热点问题,而陆地生态系统的复杂性与不确定性决定了对陆地生态系统碳平衡估测的复杂性和不确定性。为研究这一复杂性问题,已发展了许多研究方法。可分为“自下而上”与“自上而下”两种,各种方法都有其自身的优势和劣势。相关方向也已经有了大量的研究报道,但是,不同的研究由于在方法、时间与空间尺度等存在的差异,使得许多研究结果和预测很难被有效的整合或适用于大范围甚至全球水平。综述了陆地碳平衡的主要研究方法,分析和比较了各方法的特点,指出在研究中对不同方法的结果进行分析和比较,以及采用综合方法的必要性。     

一些海洋浮游植物量子产值的研究

现场实验以及用硅藻、金藻和绿藻所做的实验表明,在光饱和深度以下,随着深度的增加,浮游植物的量子产懂具有不变、增加和下降3种垂直变化趋势。偏离理论模式的后两种结果可能是由浮游植物的光强适应(Light-shade adaptation)等原因引起。还探讨了量子产值作为初级生产力模型和光利用效率模型中的参数的问题。     

四川省部分牛病毒性腹泻/粘膜病血清中和抗体检测

应用细胞中和试验对四川黄牛、水牛、奶牛、牦牛共243份血清进行病毒性腹泻/粘膜病(BVD/MD)的中和抗体检测,结果显示,水牛阳性率较高,达50.0%(21/42),其次为牦牛,达37.5%(15/40),奶牛达26.6%(38/143),黄牛最低,为22.2%(4/18).表明该病有蔓延和扩大的趋势,值得高度重视.     

Determining the involvement of two aminopeptidase Ns in the resistance of Plutella xylostella to the Bt toxin Cry1Ac: cloning and study of in vitro function

The cloning, expression in vitro, and characterization of two aminopeptidase Ns (APN5s and APN2s) isolated from the midgut of Cry1Ac-resistant (R) and susceptible (S) strains of Plutella xylostella larvae are presented in this paper. The deduced amino acid sequences of APN5s included C-terminal GPI-modification sites, the gluzincin aminopeptidase motif GATEN, and three N-glycosylated sites; those of APN2s had no GPI-modification sites, had gluzincin aminopeptidase motif GAMEN, and had four N-glycosylated sites. O-glycosylated sites were not predicted for either APN. Because APN2R and APN2S cDNAs contained the same nucleotides, only full-length cDNAs encoding APN5R and APN5S were expressed in Trichoplusia ni cells. Far-Western blotting showed that the expressed receptor APN5 bound to the Cry1Ac toxin. An enzyme-specific activity experiment also showed that APN5 genes were expressed in T. ni cells. ELISA revealed no differences in the binding of expression proteins from the resistant and susceptible strain with Cry1Ac.     

昆虫细胞(Sf21)悬浮培养过程中生长限制性基质间歇补加技术的应用

基于Sf21昆虫细胞在悬浮培养过程中所表现出的生长代谢特征,提出以培养液中残糖浓度作为控制参数,并利用限制性基质(葡萄糖和蛋白水解物)的间歇补加技术调控细胞生长的方案。实际控制表明：与批培养相比,Sf21细胞在两种具代表性的昆虫细胞培养基(IPL-41和TC-100)中的生长期和稳定期都得到了有效的延长。TC-100培养液中最高细胞培养密度由3.0×10⁶ cells/mL提高到6.5×10⁶ cells/mL;IPL41培养液中最高细胞培养密度则由7.05×10⁶ cells/mL提高到9.0×10⁶cells/mL。由于限制性基质的间歇补加技术是利用较确定的营养成分来代替复杂昂贵的补料培养基,因此更适合于昆虫细胞的大规模高密度培养。     

Localization of angiotensin II in pig ovary and its effects on oocyte maturation in vitro

The renin-angiotensin system (RAS) has been found in mammalian ovarian tissue; however, its physiological role is unclear. This study examined the content of angiotensin II (Ang II) in porcine follicular fluid (pFF), Ang II localization and its receptors in ovary, and the effects of Ang II on porcine oocyte maturation. The concentrations of Ang II were 6951.82 +/- 1295.83, 3502.99 +/- 679.10, 3147.89 +/- 690.60, and 2545.92 +/- 407.01 pg/ml in pFF from small, medium, large, and extra-large follicles, respectively. In addition, Ang II was found on zona pellucidae (ZP) and granulosa cells by immunoreactive staining. The distribution of AT1, an Ang II receptor subtype, was in accordance with that of Ang II. However, AT2, another Ang II receptor, was mainly distributed in the stroma and thecal layers of follicles. When oocytes were cultured in media containing various concentrations of Ang II, a higher (P<0.05) proportion of oocytes reached metaphase II (MII) in the medium with 100 ng/ml (87.0%) than without Ang II (61%). When oocytes from different sizes of follicles were separately cultured in media containing 100 ng/ml Ang II, maturation rates were significantly higher in oocytes from small (61.5%) and medium (85.1%) follicles than that of their controls (45.1 and 72.6%, respectively). However, addition of Ang II inhibited nuclear maturation in oocytes from large follicles (77.8% versus 87.3%). Fertilization and male pronuclear (MPN) formation rates of oocytes matured in medium containing 100 or 1000 ng/ml of Ang II were higher (P<0.05) than that of oocytes matured in medium containing 0 or 10 ng/ml Ang II. Glutathione content in oocytes cultured for 44 h in medium containing 100 or 1000 ng/ml of Ang II was also higher (P<0.01) than that of oocytes cultured in medium containing 0 or 10 ng/ml Ang II. In conclusion, Ang II was present in porcine ovaries and may regulate follicle growth and oocyte maturation.     

施用玉米秸秆和接种蚯蚓后几种土壤活性有机碳的动态变化

通过室内培养试验,研究在施用玉米秸秆和接种蚯蚓后,土壤微生物生物量碳(SMBC),水提取碳(WEOC),碳水化合物(CHOC)和酚类物质(PEOC)等活性有机碳组分的动态变化。研究结果表明,在不施秸秆或表施秸秆的情况下,接种蚯蚓对四种活性有机碳组分含量都有一定的促进作用,且在表施秸秆的情况下达到显著水平,其SMBC、WEOC、CHOC和PEOC的含量与不接种蚯蚓相比,分别增加了33.50%、43.13%、68.21%和30.28%。接种蚯蚓在混施秸秆的处理中只有WEOC的含量增加,而SMBC和CHOC含量分别降低了11.04%和16.63%,PEOC的变化不明显。不论接种蚯蚓与否,秸秆的施用对4种组分都有显著的促进作用,其中秸秆混施处理的作用最显著。接种蚯蚓和秸秆施用都能提高土壤WEOC的质量(CHOC/PEOC的比值)。方差分析表明,蚯蚓、秸秆和时间对活性碳组分含量都有显著影响,并且因子间存在强烈的交互作用。土壤活性有机碳各组分除SMBC以外,WEOC、CHOC和PEOC的含量变化受秸秆因子的影响最大,方差解释比例v分别达到82.35%、62.53%和75.82%。试验结果也表现出较一致的随时间的波动性。相关性分析表明,所测定项目SMBC、WEOC、CHOC和PEOC之间有显著的相关性。     

环境因子对沟金针虫呼吸代谢的影响

为了探讨沟金针虫Pleonomus canaliculatus对不同环境条件的适应性, 应用多通道昆虫呼吸仪测定了不同温度、O₂浓度、光照强度和湿度条件下沟金针虫的呼吸率。结果显示: 沟金针虫的呼吸模式为不规则波动型。温度和光照强度对沟金针虫的CO₂释放率影响突出, 不同处理间差异显著; 不同温度条件下, CO₂释放率最小和最大值分别为5℃时的7.22 μL/h和35℃时的180.74 μL/h, 两者间存在极显著差异（P<0.01）; 强光条件下的沟金针虫呼吸代谢强度大约是无光条件下的2倍（P<0.05）。不同的O₂浓度和空气相对湿度对沟金针虫的CO₂释放率无明显影响。同时确定了沟金针虫呼吸速率对温度的敏感性——Q₁₀值。结果表明沟金针虫在呼吸代谢过程中对温度和光照反应敏感, 对低氧和湿度环境的适应性较强。     

转瓶内部结构对无血清悬浮培养昆虫细胞的影响

以昆虫细胞为宿主进行基因工程产品的开发是动物细胞培养领域十分有吸引力的研究方向[1] 。由于昆虫细胞对营养要求极高 ,且对培养环境非常敏感 ,所以一般是在含有兼具营养及保护功能的胎牛血清的培养基中进行培养。血清一方面因其高额成本而限制了昆虫细胞大规模培养技术的发展 ,另一方面又因其成分复杂、富含蛋白而给外源基因表达产物的后处理带来困难。因此 ,昆虫细胞无血清培养技术的开发一直是细胞培养工程领域的研究热点 ,采用无血清培养技术取代传统的有血清培养技术已成为昆虫细胞 杆状病毒表达系统的发展趋势[2 ] 。然而 ,昆虫细…     

内蒙古毕拉河林区近十年森林景观变化及驱动力浅析

基于遥感信息和地理信息系统,在景观总体和斑块个体两个层次上,从景观总体特征、斑块个体特征及斑块相间相关特征等3个方面对大兴安岭毕拉河林区近10年来森林景观的变化进行了系统的研究．结果表明,由于近10年来人类对森林生态系统干扰的不断增强,研究区森林景观在类型、景观总体特征、斑块个体与相关特征等方面发生了较大的变化．近10年林区森林景观的发展趋势是：受人为干扰正逐步加强,作为人工景观标志的耕地、居民点面积正逐步增加．面积转移矩阵分析结果表明,1997年耕地面积增加主要是由柞树林转化而来的,占耕地构成的30．87％．景观异质性分析结果表明,研究区森林景观耕地斑块数量增加68．80％,平均面积减少4．82％,景观的优势度减少,多样性增加,斑块之间的聚集程度减弱,1988年由柞树林和针叶林等少数几种斑块在景观中占绝对优势的情况有所改变．对研究区和相关地区的自然地理、社会经济等研究表明,火干扰、森林采伐与毁林开荒等是森林景观变化的关键性趋动力．