内蒙古赛罕乌拉自然保护区狼的数量分布和食物组成

2006年1月至2008年12月,在内蒙古赛罕乌拉国家级自然保护区运用样线法和粪便分析法,对狼(Canis lupus)的生态分布和食物组成开展了研究。研究结果:保护区狼的数量至少7只,密度为(4.18±2.88)只/100km2,主要分布于保护区的圣山和庆云山核心区。在圣山主要活动于山脊、道路和沟谷;在庆云山主要活动于山脊。草兔(Lepus capensis)和植物在狼的食物组成中出现率最高,其食物组成在年度间存在显著差异(P<0.01),冬春与夏秋季节间差异不显著(P>0.05)。     

The characterisation of inducible dehydrogenases specific for the oxidation of d-alanine,allohydroxy-d-proline,choline and sarcosine as peripheral membrane proteins in Pseudomonas aeruginosa

The interaction with the cytoplasmic membrane of the inducible, membrane-bound, cytochrome-linked dehydrogenases specific for the oxidation of d-alanine, allohydroxy-d-proline, choline and sarcosine in Pseudomonas aeruginosa was investigated. The susceptibility of d-alanine dehydrogenase to solubilisation by cation depletion or by washing with high ionic strength buffers indicated that it was a peripheral membrane protein. The effect of various divalent cations in reducing the amount of enzyme released by cation depletion suggests a requirement for Mg²⁺ in the binding of d-alanine dehydrogenase to the cytoplasmic membrane. The peripheral nature of all four dehydrogenases was confirmed by examination of the molecular properties and phospholipid content of preparations of the enzymes solubilised with 1 M phosphate buffer (pH 7.0). Additional confirmatory evidence was provided by Arrhenius plots of membrane-bound activity of d-alanine and allohydroxy-d-proline dehydrogenases which were monophasic and independent of the discontinuities attributable to membrane lipid phase separations which characterise such plots of the activity of integral membrane-bound enzymes. The shape of the Arrhenius plots obtained for the activities of known integral respiratory proteins of P. aeruginosa suggests that these enzymes may remain in a fluid environment throughout the course of the phase separation.     

Environmental landscape determinants of maximum forest canopy height of boreal forests

Aims Canopy height is a key driver of forest biodiversity and carbon cycling. Accurate estimates of canopy height are needed for assessing mechanisms relating to ecological patterns and processes of tree height limitations. At global scales forest canopy height patterns are largely controlled by climate, while local variation at fine scales is due to differences in disturbance history and local patterns in environmental conditions. The relative effect of local environmental drivers on canopy height is poorly understood partly due to gaps in data on canopy height and methods for examining limiting factors. Here, we used airborne laser scanning (ALS) data on vegetation structure of boreal forests to examine the effects of environmental factors on potential maximum forest canopy height.     

A video image correlation technique for the measurement of electrophoretic mobility

The electrophoretic movement of blood cells has been examined with a video image correlator using the signal from a 625 line monochrome television camera attached to the optical arrangement. The diffraction pattern of a cell produces a characteristic signal which can be detected and registered in any television scan line to form the data of the first image frame. Under the influence of an electric field, cells moved across the television field of view and after a short interval appeared on different scan lines. The detection and registering process was repeated, and a cross-correlation function between the first and second image frame was computed. This function was stored in an output buffer which was continuously updated as fresh functions were integrated with the existing contents. The mean electrophoretic mobility of a suspension of particles can be calculated from the peak position of the integrated correlation function. Using a triangle deconvolution procedure, the relative contributions of subpopulations lymphocytes prepared from peripheral blood samples were examined.     

沙冬青脱水素基因转化紫花苜蓿的耐寒性研究

以紫花苜蓿品种‘中苜2号’为野生型材料,采用农杆菌介导法将沙冬青脱水素基因(dehydrin,AmDHN)导入紫花苜蓿基因组中并获得转基因植株,通过PCR和Southern blot杂交鉴定转基因植株,利用RT-PCR和qRT-PCR检测转基因植株中AmDHN基因及低温胁迫相关基因的表达量,并测定低温胁迫下苜蓿叶片的脯氨酸(Pro)和丙二醛(MDA)含量,从分子水平和生理指标两个层面研究转基因植株的抗寒特性,为进一步获得抗寒性较强的转基因苜蓿新材料提供依据。结果显示:(1)AmDHN基因已整合在转基因苜蓿植株基因组中,而且在不同的转基因株系中AmDHN的表达量也各不相同。(2)低温(4℃)处理后转基因植株中冷胁迫相关基因CBF2、CBF3、ProDH和CAS17的表达量明显高于同期野生对照;CBF2、CBF3和CAS17表达量在冷处理5h后都显著增加并达到最大值,而ProDH表达量在冷处理7d时最高,它们的最高值分别是对照的2.5、4、1.6和3倍左右。(3)苜蓿叶片的Pro和MDA含量均随低温处理时间延长而逐渐增加,转AmDHN基因苜蓿叶片的Pro含量始终高于同期野生型植株,而其MDA含量却始终低于同期野生型植株,且两类植株间差异均在胁迫14d时达到显著水平。因此,推测转AmDHN基因苜蓿中积累的AmDHN蛋白可能对一些酶的活性及膜系统起冷冻保护作用,从而使得转AmDHN基因紫花苜蓿的植株抗寒性提高,同时AmDHN也可能通过调控与低温相关基因的表达间接调节植物的耐低温能力。     

Genomic analysis of Pediococcus starter cultures used to control Listeria monocytogenes in turkey summer sausage.

The pulsed-field technique of clamped homogeneous electric field electrophoresis was employed to characterize and size genomic DNA of three pediocin-producing (Ped+) and two non-pediocin-producing (Ped-) strains of Pediococcus acidilactici. Comparison of genomic fingerprints obtained by digestion with the low-frequency-cleavage endonuclease AscI revealed identical restriction profiles for four of the five strains analyzed. Summation of results for 10 individually sized AscI fragments estimated the genome length to be 1,861 kb for the four strains (H, PAC1.0, PO2, and JBL1350) with identical fingerprints. Genomic analysis of the pediocin-sensitive, plasmid-free strain P. acidilactici LB42 with the unique fingerprint revealed nine AscI fragments and a genome length of about 2,133 kb. Ped- (JBL1350) and Ped+ (JBL1095) starter cultures (one each) were used to separately prepare turkey summer sausage coinoculated with a four-strain Listeria monocytogenes mixture (ca. 10(5) CFU/g). The starter cultures produced equivalent amounts of acid during fermentation, but counts of L. monocytogenes were reduced to a greater extent in the presence of the Ped+ starter culture (3.4 log10 unit decrease) than in the presence of the Ped- starter culture (0.9 log10 unit decrease). Although no listeriae were recovered from sausages following the cook/shower, appreciable pediocin activity was recovered from sausages prepared with the Ped+ strain for at least 60 days during storage at 4 degrees C. The results of this study revealed genomic similarities among pediococcal starter cultures and established that pediocins produced during fermentation provide an additional measure of safety against listerial proliferation in turkey summer sausage.