浊度法测定发酵液中L—苯丙氨酸含量

本介绍浊度测定发酵液中Ｌ－苯丙氨酸含量的方法,根据指示菌生长的细胞密度与生长培养基内所含的苯丙氨酸量在一定浓度范围内呈线性关系的原理,摸索了浊度最和达条件,结果表明浊度法测定发酵液中的苯丙氨酸含量,简便,准确性高。     

荧光法测定发酵液中的苯丙氨酸含量

本文介绍荧光测定微生物发酵液中苯丙氨酸含量的方法。它的原理是苯丙氨酸和茆三酮在pH5.8的酸性二肽溶液中能形成荧光产物。所产生的荧光再被铜离子增强并稳定之后,即可用荧光分先光度计进行测定。测定的激发光波长为365mm,发射光波长为500nm。本文对荧光测定的条件进行了研究,结果表明荧光测定发酵液中苯丙氨酸的含量是一种专一性强,灵敏度高,操作简便的微量分析方法。     

寡雄腐霉发酵液对番茄生长的影响及对灰霉病的防治作用

为了研发对番茄灰霉病高效、稳定、安全的生物农药,试验利用自主分离获得的寡雄腐霉菌株制备发酵液,采用盆栽试验研究寡雄腐霉发酵液对番茄生长的影响和对灰霉病的防治效果及机制,并在大田生产中验证其生防效果。结果表明,盆栽试验中,寡雄腐霉发酵液促进健康番茄植株生长,植株总生物量和根系生物量分别增加9.5%和15.4%,提高了植株叶绿素含量、根系活力及氮、磷、钾吸收量,并使带病番茄植株的发病率和病情指数分别降低57.2%和60.3%,相对防治效果达60.3%,施用寡雄腐霉发酵液对番茄叶片细胞膜具有保护性,降低丙二醛含量,提高病原性相关酶""超氧化物歧化酶、多酚氧化酶和苯丙氨酸解氨酶活性。后续田间试验中寡雄腐霉发酵液对番茄灰霉病的防治效果达71.2%。说明寡雄腐霉发酵液能有效防治番茄灰霉病,还具有促进番茄生长的作用,并且可诱导番茄植株对病原菌的防御作用,应用前景广泛。     

H-13木霉对水稻硝酸还原酶及氮、磷、钾的影响*

采用离子束对哈茨木霉进行注入并筛选出H-13菌株,该菌株发酵液含有对水稻生长有显著促进作用的物质;经对喷施该菌株发酵液后的水稻硝酸还原酶(NR)活力及其N、P和K含量的测定,发现该菌株发酵液促进水稻生长与提高NR活力、增强对N、P和K的吸收有关。     

H-13木霉对水稻硝酸还原酶及氮、磷、钾的影响

采用离子束对哈茨木霉进行注入并筛选出H-13菌株,该菌株发酵液含有对水稻生长有显促进作用的物质;经对喷施该菌株发酵液后的水稻硝酸还原酶(NR)活力及其N、P和K含量的测定,发现该菌株发酵液促进水稻生长与提高NR活力、增强对N、P和K的吸收有关。     

用浊度法测定发酵液中谷氨酸含量

大肠肝菌谷氨酸缺陷型只有在加有谷氨酸的培养基中才能生长,且其生长的细胞密度与谷氨酸加入量在一定浓度范围内是正相关,故可以用它作为指示菌来测定发酵液中谷氨酸的含量。     

重铬酸钾-DNS比色法测定发酵液中乙醇含量

发酵液中往往含有一些还原性物质,如葡萄糖等,用经典的重铬酸钾氧化比色法来测定发酵液中乙醇含量时,往往出现结果偏大的现象.为了测定发酵液中乙醇含量,在经典重铬酸钾氧化比色法基础上,使用DNS氧化比色法测定葡萄糖含量,修正乙醇含量的测定结果.统计分析发现,经改良的重铬酸钾-DNS比色法测定含葡萄糖的乙醇标准溶液时相对误差均值为0.95%,远小于传统的重铬酸钾氧化比色法的相对误差均值18.07%,在精密度相似情况下提高了准确度,更适宜用于测定含葡萄糖等还原性成分的发酵液中乙醇含量.     

水果中阿斯巴甜的研究

采用高效液相色谱-三重四级杆串联质谱(HPLC-QQQ-MS/MS)对橙等8种水果中的苯丙氨酸、天冬氨酸和阿斯巴甜进行测定,采用气相顶空(HS-GC)对水果中的甲醇进行测定,并进行阿斯巴甜的模拟合成实验,研究在水果中是否存在阿斯巴甜及合成阿斯巴甜所必须的苯丙氨酸、天冬氨酸和甲醇以及它们之间的浓度关系。实验结果表明:8种水果中均含有阿斯巴甜、苯丙氨酸、天冬氨酸和甲醇。其中阿斯巴甜的含量为23.4～117μg/kg,天冬氨酸含量为8.72～186 mg/kg,苯丙氨酸含量为1.84～84.2 mg/kg,甲醇含量为1.81～248mg/kg。不同水果中阿斯巴甜含量差异不大,而苯丙氨酸、天冬氨酸和甲醇的含量差异较大。阿斯巴甜的含量与苯丙氨酸、天冬氨酸和甲醇的含量无明显相关性。     

绞股蓝内生真菌抗大肠杆菌抗菌机制的研究

【目的】药用植物内生真菌是一种新型抗生素的微生物资源,研究绞股蓝内生真菌JY25的抗菌机制对内生真菌的研发具有重要意义。【方法】以二倍稀释法测定发酵液的最小抑菌浓度(MIC)和最小杀菌浓度(MBC);以MIC测定发酵液对大肠杆菌生长的抑制作用;扫描电镜观察发酵液作用下的大肠杆菌形态变化;同时,以β-半乳糖酶、碱性磷酸酶和电导率测定发酵液对细胞膜和细胞壁的损伤效果;采用考马斯亮蓝法检测发酵液对蛋白质合成的影响。【结果】JY25发酵液对大肠杆菌MIC为7 g/L、MBC为14 g/L;MIC浓度的发酵液使细菌对数生长期延迟12 h,菌体形态发生严重的畸形和破损;随着抑菌作用时间的延长,β-半乳糖酶含量增加、电导率增加,同时,实验发现大肠杆菌蛋白质合成异常,未检测到碱性磷酸酶。【结论】绞股蓝内生真菌JY25主要以破坏细菌的细胞膜及影响细菌蛋白质合成而抑制细菌生长。     

甘油转化生产1,3-丙二醇发酵液中甘油含量的测定

对文献介绍滴定法测定甘油的方法进行了改进,使之能够用于1,3－丙二醇发酵液中甘油含量测定。实验表明,化学滴定法测定结果具有较好的准确性和重复性,与酶法和变色酸比色法相比,测定结果接近,化学滴定法测定发酵液中甘油含量是一个较为经济简便的方法。     

Recent advances in the study of Kaposi's sarcoma-associated herpesvirus replication and pathogenesis

It has now been over twenty years since a novel herpesviral genome was identified in Kaposi's sarcoma biopsies. Since then, the cumulative research effort by molecular biologists, virologists, clinicians, and epidemiologists alike has led to the extensive characterization of this tumor virus, Kaposi's sarcoma-associated herpesvirus(KSHV; also known as human herpesvirus 8(HHV-8)), and its associated diseases. Here we review the current knowledge of KSHV biology and pathogenesis, with a particular emphasis on new and exciting advances in the field of epigenetics. We also discuss the development and practicality of various cell culture and animal model systems to study KSHV replication and pathogenesis.     

The structure, reproduction and taxonomy of Vidalia and Osmundaria (Rhodophyta, Rhodomelaceae)

Comprises species occurring mostly in subtidal habitats in tropical, subtropical and warm-temperate areas of the world. An analysis of the type species, V. spiralis (Sonder) Lamouroux ex J. Agardh, a species from Australia, establishes basic characters for distinguishing species in the genus. These characters are (1) branching patterns of thalli, (2) flat blades that may be spiralled on their axis, (3) width of the blade, (4) primary or secondary derivation of sterile and fertile branchlets and (5) position of sterile and fertile branchlets on the thalli. Application of the latter two characters provides an important basic method for separation of species into three major groups. Osmundaria , a genus known only in southern Australia, was studied in relation to Vidalia , and its separation from the Vidalia assemblage is not accepted. Species of Vidalia therefore are transferred to the older genus name, Osmundaria. Two new species, Osmundaria papenfussii and Osmundaria oliveae are described from Natal. Confusion in the usage of the epithet, Vidalia fimbriala Brown ex Turner has been clarified, and Vidalia gregaria Falkenberg, described as an epiphyte on Osmundaria pro/ifera Lamouroux, is revealed to be young branches of the host, Osmundaria prolifera.     

New or rare chromosome counts in Artemisia L. (Asteraceae, Anthemideae) and related genera from Kazakhstan

Fifteen chromosome counts of six Artemisia taxa and one species of each of the genera Brachanthemum, Hippolytia, Kaschgaria, Lepidolopsis and Turaniphytum are reported from Kazakhstan. Three of them are new reports, two are not consistent with previous counts and the remainder are confirmations of very scarce (one to four) earlier records. All the populations studied have the same basic chromosome number, x = 9, with ploidy levels ranging from 2x to 6x. Some correlations between ploidy level, morphological characters and distribution are noted.     

肝癌中HBV和HCV基因和抗原的分布及意义

采用原位分子杂交方法检测HCV RNA及HBV X基因;采用免疫组织化学方法研究HCV核心抗原,非结构区C33c抗原及HBxAg在肝细胞肝癌中的定位及分布.结果表明(1)HCV RNA、HBV X基因在肝细胞肝癌组织检出率分别为40%(55/136)和82%(112/136).HCV RNA定位于癌细胞的胞浆内,阳性细胞呈散在、灶状及弥漫分布三种形式;HBV X基因在肝癌细胞中的分布呈胞浆型、核型及核浆型,阳性细胞也呈上述三种分布形式;(2)HCV C33c抗原、核心抗原在肝细胞肝癌中的阳性率为81%(133/164)及86%(141/164).C33c抗原定位于癌细胞及肝细胞的胞浆内;核心抗原既定位于癌细胞核中,又可定位于胞浆中.C33c抗原阳性细胞以灶状分布为主;而核心抗原阳性细     

Selection with two alleles and complete dominance

For a plant selection model with frequency-independent viabilities, fertilities and selfing rates, it is shown that apart from global fixation, for certain parameter combinations a protected polymorphism and facultative fixation (either allele may become fixed according to initial frequencies) may both occur. Facultative fixation requires different selling rates for the dominant and recessive type. Protection of the polymorphism requires resource allocation for male and female function. In this connection the problem of purely genetically caused population extinction is discussed.
For general frequency dependence and regular segregation, the chances for establishment of a completely recessive gene are compared to those of a completely dominant gene. It is proven that the process of establishment of the recessive gene, despite a fitness advantage, may be considerably endangered by drift effects if random mating prevails. The recessive gene may reach the same effectivity in establishment as a dominant gene, only if the recessive homozygote mates exclusively with its own type during the period of establishment.