黑莓果实色素的稳定性分析

研究了光照、温度、pH值、氧化剂（H2O2）和还原剂（Na2SO3）对黑莓（Rubus spp．）果实色素水溶液稳定性的影响。结果表明,黑莓果实色素为水溶性花色苷类化合物,对光和热有较好的耐受性,对pH、H2O2和Na2SO3较敏感,且耐还原性略强于耐氧化性。在小于pH4．0、温度低于50℃及避光条件下黑莓果实色素的稳定性较好,可作为食品色素添加剂使用。     

不同黑莓品种的抗冻性分析

采用电导法测定了7个黑莓（Rubusspp．）品种及1个树莓品种（对照）经冷冻处理后电解质渗出率的变化,并用二项式和Logisties方程对测定数据进行了拟合。结果表明,经0℃至～35℃的冷冻处理后,7个黑莓品种枝条的电解质渗出率大多高于对照;黑莓品种‘Young’枝条的电解质渗出率相对较小。二项式的拟合度高于Logistics．方程,二项式拟合结果表明,供试黑莓品种的抗冻性均低于树莓品种‘Reveille’,其中黑莓品种‘Young’的抗冻性较强,LT50为-31．0℃;黑莓品种‘Brazos’和‘Arapaho’的LT50分别为-19．4℃和-19．9℃,抗冻性较弱。     

采收成熟度对油桃贮藏品质的影响

以‘秦光2号＇油桃为材料,研究了5个采收成熟度油桃果实在冷藏过程中呼吸速率、硬度、可溶性固形物含量（SSC）、可滴定酸含量（TA）的变化.结果表明：（1）冷藏过程中,完熟果实（第V成熟度）在贮藏15 d后最先到达呼吸高峰,未成熟果实（第Ⅰ、Ⅱ、Ⅲ、Ⅳ成熟度）则成熟度越低呼吸高峰出现的越早,且峰值越高.（2）冷藏过程中,果实硬度和TA逐渐下降,不同成熟度果实硬度变化除第Ⅲ成熟度和第Ⅳ成熟度之间差异不显著外,其余成熟度间均有显著差异（P＜0.05）;不同成熟度果实在贮藏前期TA差异显著,但后期差异不显著;SSC在贮藏过程中表现出先升高后下降趋势.（3）在冷藏条件下,成熟度越低的果实对低温的敏感性越高,越易发生冷害.（4）第Ⅳ成熟度果实（果实底色呈乳白色,SSC 11.4%,硬度7.3 kg·cm^-2）在冷藏期间呼吸高峰出现时间晚,能保持相对较高的果实硬度和可溶性固形物含量,贮藏后货架期好果率高,贮藏效果佳,为最适宜的采收成熟度.     

黑莓品种'Boysen'鲜果贮藏特性的研究

对黑莓(Rubus spp. )品种'Boysen'不同成熟度(七成熟、八成熟和九成熟)的鲜果在常温(25 ℃)和低温(4 ℃)条件下的贮藏特性进行了研究,对贮藏时间以及贮藏前后果实的感官指标(色泽、香味和霉烂指数)、形态指标(质量和平均果径)及品质指标(可溶性固形物含量、可滴定酸含量、总花色苷含量以及固酸比)进行了比较.结果表明,不同成熟度和贮藏温度对黑莓鲜果的贮藏时间有明显影响,常温条件下九成熟、八成熟和七成熟果实的贮藏时间分别为3、4和5 d,低温条件下则分别为7、9和14 d;果实霉烂指数则随成熟度的提高及贮藏时间的延长不断提高,成熟度或贮藏温度越低(大于0 ℃),霉烂指数越小,果实的贮藏时间就越长;七成熟和八成熟的果实贮藏后色泽加深、香味变浓,而九成熟果实贮藏前后色泽和香味变化不大.采摘时不同成熟度的果实形态指标和品质指标具有一定的差异,其中,果实成熟度越大,果实质量、平均果径、可溶性固形物含量、固酸比及总花色苷含量越高,可滴定酸含量越低.低温及常温下贮藏后果实质量及平均果径、可溶性固形物含量和可滴定酸含量均不同程度减少,而固酸比和总花色苷含量均不同程度提高,但在低温贮藏条件下各项指标的变化幅度明显小于常温.总体上,在低温条件下,八成熟果实的霉烂指数低,贮藏时间较长,贮藏后的果实质量和平均果径变化幅度小,可溶性固形物含量、可滴定酸含量和总花色苷含量以及固酸比逐渐接近九成熟果实,果实品质提高.因而,在实际生产中宜采收八成熟果实并在4 ℃条件下贮藏和运输,能较好地保持黑莓鲜果的品质.     

猕猴桃果实成熟进程中木葡聚糖内糖基转移酶mRNA水平的变化

以中华猕猴桃（ActinidiachinensisPlanch．）果实为试材,木葡聚糖内糖基转移酶（XET）cDNA为探针,研究果实成熟进程中XETmRNA的变化规律,探讨XET在果实后熟软化过程的作用。结果表明,20℃下外源乙烯处理可促进XETmRNA的积累,且这种效应因乙烯处理时间的加长而加强,进而加速了果实软化;0℃处理可抑制XETmRNA的增加,延缓果实软化,但当果实转入20℃后熟时,果实硬度迅速下降,而XETmRNA水平变化不明显。认为XET可能只是一种诱导酶,由它引起的细胞壁解聚并非是猕猴桃果实后熟软化的关键因子。     

桃果实采后微粒体膜Ca2+-ATPase活性与膜脂过氧化

以常温（25℃）和低温（4℃）贮藏的迎庆桃果实为试验材料,对其果实硬度、呼吸强度进行了测定,并对微粒体膜Ca^2＋-ATPase、超氧化物歧化酶（SOD）活性、氧自由基变化和膜的伤害程度进行了研究.结果表明,随桃果实衰老,常温贮藏的果实硬度迅速下降、微粒体膜上的Ca^2＋-ATPase活性、SOD活性和O2-产生速率均呈跃变式变化,先升高后降低;膜脂过氧化产物MDA的含量逐渐增加;与常温相比,低温可以抑制果实硬度的下降、呼吸速率、Ca^2＋-ATPase和SOD活性的下降及推迟峰值的出现,同时降低O2^-产生速率和MDA含量.以上结果表明,桃果实衰老与细胞质内Ca^2＋稳态的破坏和膜脂过氧化作用的加强有密切关系.     

桃果实采后贮藏过程中细胞壁多糖的变化

以‘雨花三号’水蜜桃果实为试材,分别在5℃（低温）和20℃（常温）贮藏一段时间后,研究桃果实采后细胞壁多糖降解、硬度以及乙烯释放速率的变化特征。结果表明,乙烯释放高峰明显滞后于果实采后硬度的快速下降期。不同温度下贮藏过程中果实细胞壁多糖变化的对比表明,低温抑制了细胞壁果胶和细胞壁其余组分的变化,从而抑制了果实的软化。富含半乳糖醛酸的果胶主链断裂。果胶和细胞壁其余组分也发生了半乳糖和阿拉伯糖等中性糖的损失,说明果胶和细胞壁其余组分的增溶及其侧链中性糖的降解也是桃果实采后软化的重要因素,这可能是由多种相关多糖降解酶的作用所导致的。但半纤维素多糖中中性糖的降解对桃果实采后软化的进程并没有影响。     

不同成熟度杨梅果实采后呼吸速率、乙烯释放速率和品质的变化

以3个品种杨梅果实为材料,将采后果实分为未成熟(immature)、成熟(mature)和完熟(ripe)3种不同成熟度,在20℃下48 h贮藏过程中,每隔3 h检测一次呼吸速率和乙烯释放速率,并分析成熟过程相关的品质变化.结果表明,未成熟和成熟果实的呼吸速率和乙烯合成变化呈现典型的跃变型果实特征,而在完熟果实中检测不到呼吸和乙烯跃变过程.未成熟和成熟杨梅果实中PAL活性趋于提高,而完熟果实的呈下降变化,这一结果与矢车菊-3-葡萄糖苷(Cy-3-Glu)含量变化相吻合;CIRG值与杨梅果实Cv-3-Glu含量呈极显著正相关(r=0.96**).结果显示杨梅果实属于跃变型果实.     

脂氧合酶与猕猴桃果实后熟软化的关系

２０ ℃下贮藏果实的脂氧合酶（ＬＯＸ） 活性随着后熟进程持续上升,其活性与果实硬度的变化呈极显著负相关,油酸、亚油酸和亚麻酸等不饱和脂肪酸的组分比例变化较大,而棕榈酸和硬脂酸等饱和脂肪酸的组分比例变化很小;０ ℃贮藏果实中的ＬＯＸ 活性被强烈抑制,果实后熟软化进程被明显延缓,５ 种脂肪酸组分比例变化均较平稳;外源乙烯处理显著促进了ＬＯＸ 活性的增加,加速了果实后熟软化进程。     

中甸角蒿光合作用对生长光强的响应

在原生地和引种地对高山花卉中甸角蒿（1ncarvillea zhongdianensis）光合作用和叶片性状对生长光强的响应进行研究。结果表明：在香格里拉,光合速率（Pn）、类胡萝卜素（Car）、色素比（Chla/b）均随光强的降低而下降;而比叶面积（SLA）、叶绿素b（Chlb）、叶氮含量（LNCa）随光强的降低而上升。中甸角蒿主要是通过叶片形态、生化效率和叶片氮分配来响应生长光强的变化,对生长光强的适应表现出较大可塑性,使得其相对比较容易引种驯化。中甸角蒿在香格里拉对光照具有较广的适应幅,从香格里拉移栽到昆明后,虽然Pn下降约10%,但RGR增加约30%,表明其可以在昆明较好生长。     

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.