Growth rate of potato tubers and endogenous contents of indolylacetic acid and abscisic acid

Potato plants ( Solanum tuberosum L. ev. Ostara) were grown in water culture and the growth rate of individual tubers was measured daily or at two day intervals. Tubers of different growth rate and/or different age (days after tuberization) were harvested and analysed for indolylacetic acid (IAA) and abscisic acid (ABA). Within individual tubers the IAA content decreases from the apical to the basal part of the tuber. Tuber age and corresponding fresh weight are negatively correlated with the endogenous IAA content. If, however, individual tubers of comparable age but different growth rates are compared, a significant positive correlation between growth rate and IAA content is revealed, while ABA showed a significant negative correlation with growth rate. Removal of all fast-growing tubers from individual plants causes an increase in the growth rate of the remaining tubers within 3–4 days. This coincides with a particularly steep increase in IAA content. The data support the idea that endogenous IAA content may be one factor responsible for controlling the growth rate ("sink-activity ") of individual tubers.     

热带不同生境稀有放线菌分离

通过物理和化学方法对海南清澜港红树林、海南东寨港红树林、湛江红树林、深圳红树林、吊罗山原始森林、儋州橡胶林和海口火山口等7处热带不同生境土壤样品预处理,共分离到114株放线菌。用显微镜形态观察和菌落形态观察对分离到的放线菌初步归类,从中选取13株菌进行16SrDNA序列分析,并构建系统发育树进行类群。由初步的归类结果对热带不同生境稀有放线菌的类群分布进行分析比较,水生环境和非水生环境以及不同的非水生环境之间,发现稀有放线菌类群分布有着明显差异。     

玉米根系分布空间和空间密度分布的数学模型

应用重积分研究了土壤层中散根型和直根型玉米根系的分布空间,同时研究了玉米根系的空间密度分布．     

呼吸内科病原菌的分布及耐药情况

目的：对十堰市人民医院2011年呼吸内科病原菌的分布及耐药情况进行研究,为临床合理使用抗菌药物及控制医院感染提供依据。方法：采用临床流行病学调查方法回顾性收集分析2011年1月-2011年12月呼吸内科病原菌分布及主要病原菌耐药率,对分离鉴定出的病原菌选用常用抗生素进行药敏实验,实验采用K-B法按NCCLS标准进行。结果：病原菌以革兰阴性杆菌为主,其中又以肺炎克雷伯菌、大肠埃希菌、铜绿假单胞菌为主,革兰阳性球菌以金黄色葡萄球菌为主。产酶和不产酶肺炎克雷伯菌、大肠埃希菌及金黄色葡萄球菌耐药率有明显差异。铜绿假单胞菌对头孢噻肟、氨曲南耐药率较高。结论：应根据药敏结果合理使用抗生素,以提高治疗效果,减少耐药菌株产生,预防医院内感染。     

Frequency Distribution of F-Latencies (DFL) has Physiological Significance and Gives Distribution of Conduction Velocity (DCV) of Motor Nerve Fibres With Implications for Diagnosis

On electrical stimulation of a peripheral motor nerve, a delayed and reduced F-response is obtained, which is known to occur due to random backfiring of a few percent of the motor nerve fibres at the spinal end after antidromic conduction. F-latencies obtained from multiple stimulations vary in latency, size and shape because of this randomness. We hypothesised that, being a random process, recruitment of fibres for F-response would depend on the distribution of conduction velocity (DCV) for motor nerve fibres directly, and therefore, a frequency distribution of F-latencies (DFL) from such multiple F-responses would be an approximate mirror image of DCV, latency being inversely proportional to velocity. First, obtaining DFL from many human subjects, we have shown that this is a reproducible parameter for a nerve trunk of a subject, and hence reveals a new physiological phenomenon. DFL has a single peaked distribution, which is also expected for the DCV of a normal healthy motor nerve. To validate its hypothesised relationship to DCV further, DFLs were obtained from both median nerves of patients with unilateral carpal tunnel syndrome (CTS). The patterns of DFL from both sides remained almost the same except for a delay shift equal to that in between the two M-responses, which lends support to this hypothesis. DFL, and DCV as its suggested mirror image, appear to change systematically with certain known disorders such as cervical spondylosis, even at a subclinical stage, which needs further study. This also indicates that DFL may become a new and improved investigative diagnostic tool in neurophysiology.     

2010-2011年重症监护病房病原菌分布及耐药性分析

目的 分析综合性重症监护病房(ICU)在2010-2011年间常见病原菌的分布及其耐药现状,为临床合理用药和控制医院感染提供参考依据.方法 对2010-2011年从ICU医院感染患者的各类标本中分离出病原菌共为1949株(1079株、870株),采用K-B纸片扩散法进行药物敏感试验,检测病原菌耐药性.结果 以呼吸道标本(痰和导管)的分离率最高为72.1％、病原菌以革兰阴性杆菌为主占66.9％,分别占2010年、2011年标本总量的62.3％和72.4％,革兰阴性杆菌呈上升趋势;其次为真菌感染占19.2％( 22.0％、15.6％),革兰阳性球菌占12.2％( 14.2％、9.7％).病原菌的耐药率普遍较高,耐甲氧西林金黄色葡萄球菌(MRSA)检出率为25.8％,大肠埃希菌和肺炎克雷伯菌的ESBLs检出率分别为61.0％和27.2％.结论 ICU医院感染患者呼吸道感染最多,以细菌为主,尿路感染其次,以真菌为主;病原菌耐药情况严重,应加强病原菌分布及耐药率的监测以减少多药耐药菌产生、降低医院感染率.     

医院内深部真菌感染分布及耐药性分析

目的探讨大连医科大学附属第一医院深部真菌感染的常见菌种,临床病区分布及其耐药性。方法对2008年1月1日至2008年12月31日749例住院患者深部真菌感染进行分析。结果常见菌种为白色假丝酵母菌,热带假丝酵母菌,近平滑假丝酵母菌,克柔假丝酵母菌,光滑球拟酵母菌。主要病区为ICU。从标本的来源看,痰标本中真菌检出率最高,占61.1%。两性霉素B抗菌作用最强,耐药率只有3.6%。结论医院内深部真菌感染分布广泛,非白色假丝酵母菌感染明显增多,耐药菌株增多,部分治疗需联合用药。     

A Comparison Between a Parametric and a Non-Parametric Method of Estimating the Percentiles of a Difference

A parametric and a nonparametric method of estimating the percentiles of a difference are compared. The parametric method assumes an underlying normal distribution and the nonparametric method estimates the distribution from the residuals. Applications to immunology are discussed.     

鄂西发现银鹊林

1988年5月,我们在湖北省宜昌大老岭林场(东经115°50′,北纬31°03′)植被考查中发现有大片银鹊林,银鹊(Tapiscia sinensis Oliv.)属于省沽油科(Staphyleaceae)银鹊属,为落叶大乔木,树干通直,树形美丽,极为可爱,系国家三级重点保护植物。银鹊的自然分布区包括云南、四川、广东、广西、湖南、湖北、安徽、浙江等省。最近在河南伏牛山又有发现。据《湖北植物志》记载,银鹊在湖北主要见于宣恩、鹤峰、建始等县,而且常散布于山坡林中,很少成林。     

An index of spatial distribution

The index , which takes the value of −1 for a perfectly regular distribution, +1 for a highly aggregated distribution and 0 for the distribution implied by the theoretical varianceσ², is proposed and a significance table provided.     

On Mohan's Property of the Poisson Distribution

Two interesting results encountered in the literature concerning the Poisson and the negative binomial distributions are due to Moran (1952) and Patil & Seshadri (1964), respectively. Morans result provided a fundamental property of the Poisson distribution. Roughly speaking, he has shown that if Y, Z are independent, non-negative, integer-valued random variables with X = Y | Z then, under some mild restrictions, the conditional distribution of Y | X is binomial if and only if Y, Z are Poisson random variables. Motivated by Morans result Patil & Seshadri obtained a general characterization. A special case of this characterization suggests that, with conditions similar to those imposed by Moran, Y | X is negative hypergeometric if and only if Y, Z are negative binomials. In this paper we examine the results of Moran and Patil & Seshadri in the case where the conditional distribution of Y | X is truncated at an arbitrary point k – 1 (k = 1, 2, …). In fact we attempt to answer the question as to whether Morans property of the Poisson distribution, and subsequently Patil & Seshadris property of the negative binomial distribution, can be extended, in one form or another, to the case where Y | X is binomial truncated at k – 1 and negative hypergeometric truncated at k – 1 respectively.     

我国泥盆纪鱼类的分布、组合和性质

文中记述了我国泥盆纪鱼类化石分布情况,并根据已描述的化石建立8个组合。     

Distribution of charged pterins in nonmethanogenic archaebacteria

Pterin content was surveyed in nine species of nonmethanogenic archaebacteria comprised of six species of halobacteria, two species of Sulfolobus, and one specie of Thermoplasma. The results indicated the presence of the sulfate-containing dimeric pterin sulfohalopterin-2 in three species of halobacteria, Halobacterium marismortui, halobacterial strain GN-1, and Halobacterium volcanii. The phosphate-containing dimeric pterin phosphohalopterin-1 was present in three other species of halobacteria, Halobacterium salinarium, Halobacterium halobium, and Halococcus morrhuae. Evidence is presented that these halopterins exist in the halobacteria as tetrahydropterin derivatives. A positively charged monomeric pterin, solfapterin (erythro-neopterin-3-D-2-deoxy-2-aminoglucopyranoside), was found to be present in Sulfolobus solfataricus and a negatively charged pterin was induced when S. solfataricus was grown in a medium containing homogentisic acid (2,5-dihydroxyphenylacetic acid). This negatively charged pterin was not present when the cells were grown in the normal medium. Another positively charged pterin found in Thermoplasma was determined to be different from solfapterin based on its paper electrophoresis properties. Uncharged pterins were also identified in all of these bacteria, however, no attempt was made to elucidate the structure of these uncharged pterins. Pterin content was found to vary in the different bacteria and to depend on the conditions under which the cells were grown.     

Analysis and implications of mutational variation

Variation from new mutations is important for several questions in quantitative genetics. Key parameters are the genomic mutation rate and the distribution of effects of mutations (DEM), which determine the amount of new quantitative variation that arises per generation from mutation (V _M ). Here, we review methods and empirical results concerning mutation accumulation (MA) experiments that have shed light on properties of mutations affecting quantitative traits. Surprisingly, most data on fitness traits from laboratory assays of MA lines indicate that the DEM is platykurtic in form (i.e., substantially less leptokurtic than an exponential distribution), and imply that most variation is produced by mutations of moderate to large effect. This finding contrasts with results from MA or mutagenesis experiments in which mutational changes to the DNA can be assayed directly, which imply that the vast majority of mutations have very small phenotypic effects, and that the distribution has a leptokurtic form. We compare these findings with recent approaches that attempt to infer the DEM for fitness based on comparing the frequency spectra of segregating nucleotide polymorphisms at putatively neutral and selected sites in population samples. When applied to data for humans and Drosophila, these analyses also indicate that the DEM is strongly leptokurtic. However, by combining the resultant estimates of parameters of the DEM with estimates of the mutation rate per nucleotide, the predicted V _M for fitness is only a tiny fraction of V _M observed in MA experiments. This discrepancy can be explained if we postulate that a few deleterious mutations of large effect contribute most of the mutational variation observed in MA experiments and that such mutations segregate at very low frequencies in natural populations, and effectively are never seen in population samples.