地表火干扰下呼伦贝尔沙地樟子松林乔木层不同组分空间格局的变化

火是天然樟子松重要的生态因子,地表火对樟子松林乔木层空间格局的变化有着特殊的意义。全林木定位法调查记录了地表火干扰1年后1hm2典型样地中存活及火烧死乔木的位置坐标,利用成对相关函数g(r)进行空间点格局分析。结果表明:1)单变量空间格局分析显示,空间异质性泊松点过程零假设下,地表火干扰前所有立木、樟子松和白桦均在小尺度上呈显著性聚集分布;而地表火干扰后,樟子松林分及其乔木层不同组分的空间格局更加趋向于均匀分布,只有白桦在小尺度上仍表现为显著性聚集分布,所有立木和樟子松主要以随机分布为主。乔木层及其不同组分的随机标识零假设均不成立,火后存活的所有立木在小尺度上为均匀分布,而较大尺度上却呈现出聚集分布;火后存活的樟子松在小尺度上表现为聚集分布,而较大尺度上却呈现均匀分布;火后存活的白桦主要表现为小尺度上的聚集分布。2)双变量空间格局分析表明,所有立木、樟子松和白桦的存活立木与火烧死木之间均是相互独立的,其相互间的空间格局表现为随机分布。地表火烧死木(包括所有立木、樟子松和白桦)均在小尺度上表现为显著的正相关呈聚集分布,而较大尺度上不同程度地表现为显著的负相关为均匀分布。因此,地表火干扰下,林木的死亡过程并不是随机的,存活林木的空间格局趋于均匀分布,地表火驱动下的樟子松林自然稀疏过程削弱了存活个体间的竞争,促进了林分结构的优化和个体的生长发育,成为樟子松林演替中较活跃的生态因子。     

H5N1亚型禽流感病毒A/Guangxi/1/2005株抗药机制的研究

为研究H5N1亚型禽流感病毒(AIV)的抗药机制,本研究选取Clade2.3.4亚群中一株对金刚烷胺敏感的人源AIV A/Guangxi/1/2005(H5N1)(S-GX05),用抗流感病毒药物金刚烷胺对其进行定向诱导,筛选出一株抗药性病毒株,命名为R-A/Guangxi/1/2005(R-GX05)。通过全基因测序并与S-GX05全基因序列进行对比,结果显示S-GX05只在其M2蛋白中有一个氨基酸位点发生突变,即A30P;抗药性鉴定这两株病毒的半数药物抑制浓度(IC50)分别为0.9μM和48.9μM,表明R-GX05对金刚烷胺表现出一定程度的抗性。动物实验证实,这两株病毒对BALB/c小鼠的致病性基本一致,均表现出高致病性,其MLD50分别为4.7 log10 EID50和5.0 log10 EID50,两株病毒在小鼠体内各组织脏器中的分布及增殖能力也基本相同。这些结果表明,S-GX05在药物压力下产生抗药性后,并未引起其它生物学特性的改变。A30P的发现为进一步从分子水平上研究H5N1亚型AIV的抗药机制及新型抗流感新药的研发奠定了基础。     

大学课堂教学中学生创新能力的培养

创新人才的培养对于一个国家综合国力的提高有着重要的战略意义。大学是培养创新人才的重要基地,学生创新能力的培养关乎大学教育中人才培养的成败。在我国大学教育中,课堂教学是培养学生创新能力的主要渠道。文中认为营造创新教育环境、引导学生进行探究性学习、培养学生的思维能力以及丰富课堂教学方法和手段等是大学课堂教学中实现学生创新能力培养的重要举措。     

Isolation and Identification of Enterococcus faecalis from Fur-bearing Animals

In order to obtain Enterococcus faecalis from fur animals and evaluate its prebiotic properties,in this study,Enterococcus faecalis was isolated from the feces of healthy adult fur-bearing animals (mink,fox,raccoon dog),identified by morphological observation,biochemical test and 16S rRNA sequence analysis.The growth curve,acid production capacity and antibiotic sensitivity of the Enterococcus faecalis isolates were measured to evaluate their probiotic properties.Some strains were selected to determine their tolerance to temperature,artificial gastric juice and artificial bile salt.The results showed that five strains were Gram-positive,and their biochemical characteristics were basically consistent with the standard strains of Enterococcus faecalis,and they were identified as Enterococcus faecalis by 16S rRNA sequence analysis.The five strains all entered the logarithmic phase at 2 h after culture,and entered the stable phase at 8-10 h,and had weak acid production capacity.The resistance rate of the isolates to tetracycline and levofloxacin was 100%,followed by penicillin (80%),erythromycin (80%),gentamicin (80%) and chloramphenicol (40%).All the isolates were sensitive to ampicillin and vancomycin.Enterococcus faecalis from mink,fox and raccoon dog had strong tolerance to temperature below 60 ℃,artificial gastric juice with pH>3.0 and 0.3%-0.5% concentration of bile salt,but poor tolerance to temperature above 70 ℃,and artificial gastric juice with pH<3.0.In conclusion,five strains of Enterococcus faecalis from fur animals (mink,fox,raccoon dog) were obtained in this study.The isolated strains propagated rapidly,which were suitable for colonization and played a prebiotic role in fur animals' intestines,and had good prebiotic characteristics and stress resistance.They could be used as candidate strains for animal microbiological agents for further study.     

缠绕植物手性的系统发育分析(英文)

利用matK、rbcL与trnL基因,分析了中国薯蓣属植物缠绕手性的系统发生关系;利用matK基因,从大分类单元角度进一步分析了缠绕植物的系统特征。结果显示左、右旋缠绕植物物种存在显著的系统发育特征:matK数据中的右旋薯蓣聚成独立的进化枝与rbcL基因的分析共同支持右旋物种的单系性;rbcL和trnL的数据均较好地显示了右旋薯蓣的单系特征[除多毛叶薯蓣(D.decipiens)和甘薯(D.esculenta)外];在大分类单元上,缠绕植物手性性状则呈现出明显的多系特征。结果表明在中国区薯蓣属的分类中,手性特征是较可靠的性状特征,《中国植物志》薯蓣属章节直接将右旋物种归入周生翅组(sect.Enantiophyllum)较合理。但在世界范围上看,在小分类单元的薯蓣属内和薯蓣科及其他大分类单元内,手性特征都具有单独多次起源的性质,因此在执行分类时应当慎用这个性状。对于手性特征的起源问题,最新的观点倾向于否定南北半球物理差异相关的假说,但其结论的正确性有待商榷。结合地质事件研究薯蓣属等具有两种手性方向的小分类单元,以及构建突变体的方法,有助于最终解决植物手性的起源问题。     

Pulmonary Maturation in Canine Foetuses From Early Pregnancy to Parturition

Development of the foetal respiratory system includes both pulmonary growth and maturation. In human medicine, a higher incidence of respiratory distress is reported in newborn males. This study aimed to identify different phases of canine foetal lung maturation throughout pregnancy, to determine the stage of pregnancy in which surfactant production begins and to compare pulmonary development of male and female foetuses. Pregnant bitches (34) were subjected to elective ovariohysterectomy and allocated into four groups, according to the stage of pregnancy: 30–40 days of pregnancy (n = 10), 41–50 days (n = 10), 51–60 days (n = 10) and bitches in the first stage of parturition (n = 4). Foetal lungs were histologically processed and evaluated by optical microscopy. The pseudoglandular phase was identified between the 35th day and 46th day of gestation; the onset of canalicular and saccular periods was observed, respectively, from the 48th day and 60th day of pregnancy. Lungs from foetuses at term were in the saccular phase; thus, the development into the alveolar period occurs in the neonatal period. The histological analyses revealed that respiratory tract development is centrifugal, from upper to lower airways. Therefore, it is possible to identify distinct development periods in different portions of the same organ. In conclusion, the saccular phase of lung development begins around 57 and 60 days of pregnancy, the period in which surfactant production is believed to occur. Male and female foetuses present similar pulmonary development from early pregnancy until parturition.     

毛皮动物源粪肠球菌的分离鉴定

为获得毛皮动物源粪肠球菌,并评价其益生特性,本研究从健康成年毛皮动物（水貂、狐狸、貉）粪便中分离粪肠球菌,通过形态学观察、生化试验和16S rRNA序列分析等方法进行种属鉴定。测定分离菌株生长曲线、产酸能力、抗菌药敏感性,并挑取部分菌株测定其对于温度、人工胃液、人工胆盐的耐受能力。结果表明,分离菌株中共5株为革兰氏阳性菌,生化特性与粪肠球菌标准株基本相符,且经16S rRNA序列分析鉴定为粪肠球菌。5株菌均于培养后2 h进入对数期,8~10 h进入稳定期,且具有弱产酸能力。分离菌株对四环素、左氟沙星耐药性强,耐药率为100%,其次为青霉素（80%）、红霉素（80%）、庆大霉素（80%）、氯霉素（40%）,对氨苄西林和万古霉素敏感。水貂、狐狸和貉源的粪肠球菌对于60 ℃以下温度处理、pH>3.0的人工胃液、0.3%~0.5%浓度的胆盐耐受能力较强,对70 ℃以上高温和pH<3.0的人工胃液耐受性差。综上所述,本研究共获得5株毛皮动物源（水貂、狐狸、貉）粪肠球菌,分离菌株繁殖较快,适合在毛皮动物肠道中定植并发挥益生作用,且具有较好的益生特性和抗逆性,可作为动物用微生态制剂的候选菌种进一步研究。     

西藏波密县天麻产业发展问题研究

由于西藏波密县农业生产具有地质史独特,地形地貌复杂,气候异常,土壤种类繁多,野生植被多样的特点,给天麻生产带来机遇的同时,又带来了严峻的挑战。笔者主要从西藏波密县天麻生产的现状入手,科学地分析了西藏波密县天麻生产中存在的问题,提出了天麻生产发展的对策。     

土壤质量生物学指标研究进展

本文对近年土壤微生物、土壤酶活性和土壤动物等土壤质量生物学指标研究成果进行了综合评述。土壤微生物是土壤有机组分和生态系统中最活跃的部分,被认为是最敏感的土壤质量生物学指标:微生物生物量代表参与调控土壤中能量和养分循环及有机物质转化所对应微生物的数量,但须结合多样性研究以弥补其无法反映土壤微生物组成和区系变化的缺陷;微生物群落组成和多样性动态反映土壤中生物类群的多变性和土壤质量在微生物数量和功能上的差异;土壤微生物活性体现在土壤微生物商、微生物呼吸和代谢商等方面,应考虑生物量大小与微生物种群活性间的相关关系以反映微生物种群内的差异。土壤酶活性具有极高时效性,在较短时间内就能反映出土壤质量的变化。土壤动物通常以种类的组成和数量,土壤动物区系的相对丰度、多样性或活性作为评价土壤生物质量的敏感指标。与土壤理化指标相比,土壤生物学指标更能对土壤质量的变化做出灵敏迅速的响应,因而被广泛地用于评价土壤质量。