初生休眠解除状态和干燥处理对水曲柳种子萌发的影响

为探究初生休眠解除状态和干燥处理对水曲柳种子萌发的影响，本文以初生休眠的成熟水曲柳种子为材料，研究经不同裸层积（暖温10周+低温8周、暖温12周+低温8周、暖温10周+低温10周、暖温12周+低温10周）和干燥处理（干燥、不干燥）的水曲柳种子在适宜温度和较高温条件下的萌发表现。结果表明，初生休眠解除状态不同的水曲柳种子在不同温度下的萌发表现具有相似的规律，种子的萌发会受到干燥处理的影响。不经干燥处理的种子解除休眠越充分，其萌发能力就越强，但层积处理后的种子若经过干燥处理，则解除休眠越充分（尤其是低温时间越长），种子萌发能力下降越多。水曲柳种子次生休眠（热休眠）的诱导受种子初生休眠解除状态的影响较小，但受干燥处理影响较大。干燥处理会降低水曲柳种子的萌发能力，尤其是较高温条件下的萌发能力，初生休眠解除越充分的种子萌发受干燥处理影响越大。生产中如需对解除休眠的种子干燥处理，选择暖温10周+低温8周的层积方法处理种子效果最好。     

温度、GA3和乙烯对中国水仙休眠的解除

自然条件下,4月至7月下旬期间,中国水仙鳞茎的呼吸速率逐渐下降,7月底至8月底开始上升之后又下降。30℃高温下的鳞茎发芽延缓,发芽率下降;15℃低温有利于打破休眠,7月下旬前的鳞茎,其休眠解除所需的低温处理时间长,GA3不能破除,还延缓其休眠时间,萌发率也下降;而7月下旬后的鳞茎,短时间低温或施用GA3均能破除其休眠,提高鳞茎的发芽率和发芽整齐度;乙烯在任何阶段都有助于水仙鳞茎休眠的解除。自然条件下7月下旬前水仙鳞茎可能是内生休眠,其休眠较难打破,需要长时间的低温或施用适当浓度的乙烯,7月下旬后可能是环境休眠,短时间的低温、GA3或乙烯都能破除其休眠。     

生长调节剂和青霉素对杜梨种子萌发和下胚轴生长的影响(简报)

适当浓度的BA、GA、乙烯利和青霉素处理均可显著促进杜梨休眠种子的萌发,效果大小依次为BA、GA、青霉素、乙烯利。BA抑制下肢轴的加长生长而促进加粗生长。GA促进下胚轴的加长生长。适当浓度的乙烯利和青霉素对下肢轴加长生长和加粗生长均具促进作用。     

山楂种子休眠与后熟期间内源激素的变化（简报）

山楂种子必须经过低温层积后方可发芽。剥去种子外壳可以缩短山楂低温层积时间。山植种子发芽随着种子中ABA含量降低,GA3、ZR和IAA含量增加,以及GA3／ABA、IAA／ABA、ZR/ABA比值增大而增加,休眠解除。     

温度对经层积处理解除休眠的水曲柳种子萌发的影响

经层积处理解除休眠的水曲柳种子于10种不同温度条件下萌发的结果表明:变温条件下的种子萌发比恒温条件的好,最佳的变温条件为15℃/10℃,最佳的恒温条件是10℃,20℃以上的恒温会诱导种子产生二次休眠。     

新疆干旱区植物藜的种子异型性及其萌发机理

新疆干旱区分布的植物藜(Chenopodium album)的种子有黑色和褐色两种类型。对藜的异型性种子从形态结构、不同环境因素及激素或化学物质对萌发的影响以及同工酶谱等方面进行了研究,并对其萌发及适应异质环境的机理进行了讨论。结果表明:(1)藜的异型性种子在形态结构、萌发休眠特性等方面都存在明显差异:黑色种子种皮厚且硬,休眠,萌发慢,萌发率低;褐色种子种皮薄而软,不休眠,萌发快且萌发率高;(2)黑色种子的休眠可通过切除胚根外缘种皮得以完全解除;(3)赤霉素、乙烯利对黑色种子的萌发无明显促进作用;KNO3可较显著促进黑色种子的萌发;协同使用乙烯利和KNO3时,可显著提高黑种子萌发率,完全打破休眠;(4)黑色种子和褐色种子的酯酶、过氧化物酶及过氧化氢酶同工酶谱带存在差异;(5)黑色种子的萌发需要光照,而褐色种子则对光不敏感;低温贮藏对二者的萌发均无显著影响,尽管黑色种子的萌发率有波动。研究结果初步显示黑色种子的休眠是内源(胚)和外源(种皮)因素共同所致。藜的种子异型性及其萌发机理的形成是其对新疆干旱区异质化环境的高度适应。     

东京野茉莉种子休眠机制及其破除方法初探

以采自江西吉安官山林场5年生东京野茉莉当年自然带壳种子为材料,通过对其种子吸水率、不同层积时期种子内生理生化指标的测定、种子萌发抑制物分析,并利用各类不同药剂处理进行发芽试验,以探寻东京野茉莉种子的休眠机理及破眠方法。结果表明:(1)休眠的原因主要包括种皮障碍、缺少萌发所需激素以及种皮、胚中存在萌发抑制物,其中种皮障碍和抑制物的存在是限制种子萌发的首要因素。(2)GA3处理结合自然低温层积30d即可解除东京野茉莉种子胚的休眠,但种皮障碍始终是其种子萌发的限制因素。(3)GA3、NAA、6-BA等药剂处理均可促进种子的萌发,并以刻伤种子后用500mg/L GA3处理24h为破除该种子休眠的最有效方法。     

桃儿七种子低温层积过程中胚形态及生理生化物质变化

为探究低温层积过程中桃儿七种子胚形态及生理生化变化与休眠解除的内在联系,该研究通过低温层积处理(90 d)解除桃儿七种子休眠,观测不同层积时间种子胚形态、胚率、发芽率、营养物质(淀粉、可溶性蛋白质、可溶性糖)含量、内源激素［赤霉素(GA)、吲哚乙酸(IAA)、脱落酸(ABA)］水平及呼吸途径关键限速酶［丙酮酸激酶(PK)、琥珀酸脱氢酶(SDH)、6 磷酸 葡萄糖脱氢酶(G 6 PDH)］的活性变化。结果显示：(1)在低温层积过程中,桃儿七种子胚形态为鱼雷或子叶型胚;种子发芽率在层积后期(60~75 d)显著提高(P＜0.05)。(2)层积后,种子内淀粉含量及PK活性、SDH活性显著降低(P＜0.05),其可溶性蛋白含量和IAA含量显著升高(P＜0.05),萌发促进物和抑制物比例(GA/ABA、IAA/ABA、GA+IAA/ABA)也呈升高趋势。(3)种子胚率与其可溶性糖含量呈显著负相关关系,种子发芽率与其可溶性蛋白呈显著正相关关系(P＜0.05)。研究发现,桃儿七种子无形态休眠;种子内营养物质的分解转化为种子休眠解除过程中各种代谢活动提供能量,且淀粉可能是此过程中最主要的供能物质;磷酸戊糖途径(PPP)的活化、萌发促进物和抑制物比例的升高及IAA含量的显著上升是桃儿七解除休眠的关键。     

植物激素对几种核果类种子休眠破除和幼苗生长的效应研究

以山桃、甘肃桃、毛桃、杏、马哈利樱桃为材料 ,分别用普洛马林、GA3 、BA为处理激素 ,研究不同浓度激素对破除核果类种子休眠的效果。结果表明 GA3 0 .5μg· g-1、普洛马林3.0μg· g-1能有效破除桃、杏种子休眠 ,幼苗生长基本良好 ,激素浓度过低 ,破除休眠效果不佳 ,浓度过高虽然能提高种子发芽率 ,但幼苗生长不良。 BA无论对破除种子休眠 ,还是幼苗生长均达不到生产要求。普洛马林 1 .0～ 5.0 μg· g-1均能有效提高层积马哈利樱桃出苗率 ,3.0μg· g-1 对破除马哈利樱桃的休眠效果最好 ;GA3 、BA对破除马哈利樱桃休眠效果不明显。     

影响琼花种子休眠的因素

琼花种皮有吸水性,休眠非因种皮的不透水性造成.种仁中存在导致休眠的抑制物质,胚的抑制物质含量最高.种子须先经4℃低温层积60 d,再经25℃暖温处理90 d,而后在较低温(15℃)条件下才能解除休眠而萌发.当年成熟种胚在翌年10月才能彻底破除休眠.6-BA和GA对种胚破眠均无明显作用.     

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.