玉米赤霉烯酮产生菌在我国的分布及其特性*

从全国29个省、自治区和直辖市分离到的镰刀菌中,随机抽取335株分别接种到大米培养基上,进行变温培养。用薄层扫描法定量检测培养物在不同温度阶段的玉米赤霉烯酮含 量。检测结果表明,50.7％的受检菌株具有产生玉米赤霉烯酮的能力,分布广泛,产量范围为0.3—5143.8mg/kg大米．玉米赤霉烯酮产置与低温无必然相关性。 125株菌株(占产生菌的73.5％)在常温下即可产生玉米赤霉烯酮。经低温处理后,它们之中仅有41.6％的菌株显著增加了产量。产生菌分属7个种：禾谷镰刀菌(F．Grammearum)大刀镰刀菌(F．Culmorum),燕麦镰刀菌(F．Avenaceum),半裸镰刀菌(F．Semitectum),木贼镰刀菌(F. equiseti),紧密 镰刀菌(F．Compactum)和克地镰刀菌(F. crookwellense)。其中,禾谷镰刀菌占85.3％。     

冬性植物春化过程中玉米赤霉烯酮的内源生成及马拉硫磷对它的抑制

Stob等(1962)首先从玉米赤霉菌(Gibberella zeae,其无性世代为禾谷玫瑰镰刀菌[Fusarium roseum ’graminearum’])中分离出玉米赤霉烯酮。此后,Mirocha等(1967),Nelson等(1968)及Caldwell等(1970)先后证明玉米赤霉烯酮是某些真菌     

γ射线紫外线对镰刀攻产生玉米赤霉烯酮毒素的影响

镰刀菌（Ｆｕｓａｒｉｕｍ）经γ射线、紫外线辐射诱变后,接种于大米培养基中,经１０℃低温产毒培养,采用薄层层析方法定性定量分析培养物中的镰刀菌毒素－玉米赤霉烯酮（ｚｅａｒａｌｅｎｏｎｅ简称ＺＥＡ）。结果表明：不同蓖株对诱变剂的反应不同。产毒菌株ＮＦ５２３２、ＮＦ５９４６在较大剂量γ射线处理后,ＺＥＡ产是显著增加,但其产生的色素量下降。或者用紫外线处理,仍然产生ＺＥＡ。不产毒菌株ＮＦ６１２７、ＮＦ６１     

玉米赤霉烯酮降解菌的鉴定及其降解特性

【背景】玉米赤霉烯酮(Zearalenone,ZEN)是一种具有类雌激素作用的霉菌毒素,常会污染谷物和饲料,严重威胁动物和人类的健康。生物脱毒作为理想的去除ZEN的方法,广受关注,然而相关菌株较少,仍有待进一步筛选。【目的】明确一株玉米赤霉烯酮降解菌的生物学分类地位,并优化其赤霉烯酮降解菌降解条件。【方法】通过菌株的16S rRNA基因序列比对,构建系统发育进化树,并开展了相关培养条件的单因素优化和玉米赤霉烯酮降解动力曲线的绘制。【结果】实验菌株WLB-29经鉴定为斯塔普氏菌属(Stappia),其16S rRNA基因序列在GenBank上登录号为MT196321,该序列与模式菌株Stappia indica B106T相似性最高为97.47%,初步确定为斯塔普氏菌属潜在新种。单因素优化表明,菌株降解玉米赤霉烯酮的最佳条件为LB培养基、37℃培养、pH 8.0、2%接种量和玉米赤霉烯酮初始浓度为10mg/L,在此条件下培养144h后,玉米赤霉烯酮的降解率最高可达92.56%。【结论】菌株WLB-29具有较好的ZEN降解作用,为进一步解析菌株降解ZEN作用机理提供了研究基础,也为进一步开发利用菌株开展ZEN的生物脱毒提供了新的菌株资源。     

γ射线紫外线镰刀菌产生玉米赤霉烯酮毒素的影响

锭刀菌(Fusarium)经γ射线、紫外线辐射诱变后,接种于大米培养基中.经10℃低温产毒培养.采用薄层层析方法定性定量分析培养物中的镀刀菌毒素—玉米赤霉烯酮(zearalenone简称ZEA).结果表明:不同菌株对诱变剂的反应不同.产毒菌株NF5232、NF5946在较大剂量γ射线处理后,ZEA产量显著增加,但其产生的色素量下降.或者用紫外线处理,仍然产生ZEA.不产毒菌株NF6127、NF6123、NP6138和HD—002,经γ射线或紫外线处理后仍不产生ZEA.由此可知镰刀菌产生ZEA毒素的能力是相对稳定的,其产毒机制是由菌株本身的遗传特性决定的,一定剂量的γ射线可使低产毒菌株变为高产毒菌株.     

玉米赤霉烯酮单克隆抗体的制备及间接竞争ELISA检测方法的建立

玉米赤霉烯酮具有较强的生物毒性,检测谷物中的玉米赤霉烯酮在食品和饲料安全中具有重要的作用.将玉米赤霉烯酮与牛血清白蛋白的偶联物免疫BALB/c小鼠制备单克隆抗体,并建立基于单克隆抗体的酶联免疫法作为检测玉米赤霉烯酮的方法.结果共筛选到4株抗玉米赤霉烯酮单克隆抗体,3株抗体亚类为IgG1,1株为IgG2b.选择其中的一株杂交瘤细胞2C9制备小鼠腹水,纯化后测定了抗体效价为1/40 000.以此单抗建立的间接竞争ELISA方法,其半数抑制率(IC50)为1.90 ng/mL,检测限(IC10)为0.051 ng/mL,检测区间(IC20-IC80)为0.115-13.900 ng/mL;且对玉米赤霉烯酮有很好的特异性.回收率检测在样品含1.46-93.80 μg/kg时回收率为96.5％-113.0％.本实验建立的检测方法可用于多种谷物及饲料样本中玉米赤霉烯酮的检测.     

龙血树真菌群及其对血褐形成的影响

从柬埔寨龙血树茎杆中分离到３０３株真菌,其中镰刀菌属菌株占总分离频率的５２％,其次是短梗霉和枝孢霉。通过活体接种对血竭产生的影响试验表明,对血竭形成起重要作用的真菌主要是禾谷镰刀菌龙血树变种等４株红色镰刀菌,可使血竭形成量提高６６％－１２０％。     

玉米赤霉烯酮脱毒菌PA26-7的分离鉴定及其应用效果评价

【背景】玉米赤霉烯酮(zearalenone,ZEN)是广泛污染粮谷类作物的一种雌激素类真菌毒素,不仅给农业经济带来巨大损失,还能通过食物链对人和动物健康造成危害。【目的】从微生态制剂中筛选获得能够高效降解玉米赤霉烯酮的菌株,优化其脱毒条件,测定其在饲料中的实际脱毒效果及对饲料中植酸、维生素含量变化的影响。【方法】从微生态制剂中分离出玉米赤霉烯酮降解菌,通过细胞计数试剂盒-8 (cell counting kit-8, CCK-8)测定菌株降解玉米赤霉烯酮产物的细胞毒性和雌激素活性,通过高效液相色谱法测定分离株在培养基和饲料中的解毒效果,以及分离株在霉变的豆粕、麸皮和成品饲料中固态发酵前后维生素的含量变化,通过三氯化铁比色法测定饲料脱毒前后植酸的含量变化。【结果】从微生态制剂中筛选出一株通过分泌胞外酶高效降解玉米赤霉烯酮的贝莱斯芽孢杆菌(Bacillus velezensis) PA26-7,该菌株在培养基起始pH 4.0-8.0、培养温度25-60℃条件下均可降解玉米赤霉烯酮,产物的细胞毒性和雌激素活性均较ZEN弱。PA26-7经固态发酵72h后,饲料原料(豆粕和麸皮)及霉变的成品鸡...     

酪丁酸梭菌清除饲料中玉米赤霉烯酮的能力

研究酪丁酸梭菌吸附清除饲料中玉米赤霉烯酮的能力,为其在农作物饲料中的脱毒作用奠定基础。首先通过单因素实验确定初始菌质量浓度、pH、温度和时间的影响,并探究热、酸处理后的菌株清除玉米赤霉烯酮的能力,再采用微生物适应性进化方法驯化酪丁酸梭菌,以提高其脱毒效果。结果表明:当初始质量浓度为1.0×10~(11)个/mL的原始菌悬于pH 4.0的培养基,37℃孵育24 h时,对玉米赤霉烯酮毒素的清除效果分别为活菌组31.9%、热处理组44.2%、酸处理组50.2%,说明原始菌对玉米赤霉烯酮具有一定的清除能力。而驯化后的菌株经过热、酸处理,经验证当菌体密度为1.0×10~(11)个/mL时,酸处理后的驯化菌株对毒素的吸附效果最好,吸附率可达98.5%,有望被运用于实际生产中,从而减少饲料中的毒素含量,有利于家禽体内毒素的清除,降低毒素积累。     

有氧条件下污染禾谷镰刀菌的玉米品质变化规律和呕吐毒素的积累动态变化规律

【目的】试验旨在考察有氧条件下接种禾谷镰刀菌后玉米品质变化规律和呕吐毒素(脱氧雪腐镰刀菌烯醇Deoxynivalenol,DON;15乙酰基脱氧雪腐镰刀菌烯醇15-acetyldeoxynivalenol,15AC-DON)的积累动态变化规律。【方法】单因素试验设计,禾谷镰刀菌接种量分别为1×10~5、1×10~6、1×10~7个/g,玉米水分22%,三角瓶中培养,通氧量为1020 m~2/m~3,温度25±2°C,湿度75%±5%,时间60 d,测定不同时间点玉米培养物中的品质指标和二毒素含量。【结果】结果表明,禾谷镰刀菌接种量对为禾谷镰刀菌提供N源的粗蛋白质含量无影响(P0.05),随着培养时间的延长,提供N源的氨基酸含量呈二次曲线变化(P0.01),提供C源的粗脂肪、淀粉、粗纤维呈线性降低(P0.01)。酸价呈线性增加(P0.01),蛋白质溶解度、能量呈线性降低(P0.01),霉菌总数和毒素DON、15AC-DON呈二次曲线变化(P0.01)。禾谷镰刀菌产DON的动态规律为,0–15d毒素产量范围为0.17–0.23mg/kg,16–20d毒素产量范围为0.14–0.41mg/kg,21–60d毒素产量范围为0.06–0.15mg/kg;禾谷镰刀菌产15AC-DON的动态规律为,0–5 d毒素产量范围为1.11–5.28 mg/kg,6–15 d毒素产量范围为5.55–10.05 mg/kg,16–60 d毒素产量范围为4.68–12.06mg/kg。【结论】玉米品质随禾谷镰刀菌接种量增加和培养时间延长逐渐降低,DON和15AC-DON产量与禾谷镰刀菌接种量呈剂量依赖关系,60 d内二毒素积累存在前期、中期和后期的动态变化规律。     

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.