NaCl胁迫下SA浸种绿豆幼苗的生长及生理特征

以'中绿一号'绿豆品种为材料,对不同浓度水杨酸(SA)浸种绿豆种子在NaCl胁迫条件下的萌发、幼苗生长及相关生理指标变化进行分析.结果显示:(1)与未胁迫对照相比,未浸种对照绿豆在100～500 mmol·L-1 NaCl处理下的发芽率、芽长、根长和叶片叶绿素含量显著降低,而幼苗叶片丙二醛(MDA)与脯氨酸(Pro)含量水平显著上升(P＜0.05),且其升降幅度随NaCl胁迫浓度提高而增加;(2)与未浸种对照相比,未胁迫对照种子的萌发和幼苗的生长在20 mg·L-1 SA处理中受到抑制,而在40～80 mg·L-1 SA处理条件下得到促进,至100 mg·L-1 SA时又受到显著抑制.(3)适当浓度的SA浸种能够显著提高盐胁迫下绿豆幼苗的芽长、根长、叶绿素的含量,降低了MDA和Pro含量;在NaCl胁迫浓度为100～300 mmol·L-1时的SA适宜浓度浸种为60 mg·L-1,而500 mmol·L-1 NaCl时为80 mg·L-1.研究表明,适当浓度的SA浸种能有效缓解盐胁迫对绿豆幼苗的伤害,提高其耐盐性.     

外源水杨酸对NaCl胁迫下大豆种子萌发和幼苗生长生理的影响

以大豆种子、幼苗为试验材料,采用砂培的方法,研究了0.2mmol·L-1外源水杨酸(SA)对100mmol·L-1 NaCl胁迫下大豆种子萌发、幼苗形态及生物量、膜脂过氧化和抗氧化酶活性的影响。结果显示:NaCl胁迫下,大豆种子萌发和幼苗生长受到显著抑制,且随着胁迫时间的延长(0~3d),大豆幼苗相对电解质渗漏率、硫代巴比妥酸活性产物(TBARS)含量显著升高,超氧化物歧化酶(SOD)、过氧化氢酶(CAT)、抗坏血酸过氧化物酶(APX)活性均明显降低。外源SA促进NaCl胁迫下大豆种子萌发和根茎生长,增加幼苗生物量积累,降低幼苗叶片相对电解质渗漏率和TBARS含量,增强其叶片SOD、CAT、APX活性。研究表明,NaCl胁迫能显著抑制大豆种子萌发和幼苗生长,而一定浓度的外源SA能有效提高NaCl胁迫下大豆种子活力及幼苗抗氧化酶活性,减轻膜脂过氧化程度,缓解NaCl胁迫所造成的伤害,提高大豆幼苗抗盐胁迫的能力。     

γ-氨基丁酸浸种对番茄种子及幼苗耐盐性调节的生理机制

以番茄‘金棚一号’为材料,研究了外源γ-氨基丁酸(GABA)浸种处理对NaCl胁迫下种子萌发及幼苗生长和生理代谢的影响。结果显示:(1)NaCl胁迫显著抑制了番茄种子的萌发和胚根生长,同时导致番茄幼苗体内活性氧(O2.-、H2O2)大量积累,膜脂过氧化程度加重,幼苗叶片光合系统Ⅱ活性显著降低,幼苗的生长受到严重抑制。(2)外源GABA浸种能够显著提高盐胁迫下番茄种子的萌发和胚根的生长,并以10.00mmol.L-1 GABA浸种处理效果最好。(3)外源GABA浸种处理显著提高了NaCl胁迫下番茄幼苗根系和叶片抗氧化酶(SOD、POD和CAT)活性,降低了活性氧(O2.-、H2O2)的产生和膜脂过氧化程度,通过维持较高的光合系统Ⅱ活性,促进了幼苗的生长及生物量积累,但GABA的缓解效应存在较大的浓度差异,其中以10.00mmol.L-1 GABA处理效果较好。研究表明,10.00mmol.L-1 GABA浸种处理能够通过促进番茄种子萌发和幼苗生长来缓解盐胁迫的伤害。     

盐胁迫下黄芩种子萌发及幼苗对外源抗坏血酸的生理响应

以黄芩(Scutellaria baicalensis)种子为材料,用氯化钠(Na Cl)模拟盐胁迫条件,采用纸上发芽,研究外源抗坏血酸(As A)对盐胁迫下黄芩种子萌发及幼苗的影响。结果表明,在80 mmol·L-1 Na Cl胁迫下,黄芩种子萌发及幼苗生理指标受到显著抑制;0.50 mmol·L-1 As A处理可显著提高盐胁迫下黄芩种子的发芽势(GE)、发芽率(GR)、发芽指数(GI)、简化活力指数(SVI)以及根系总黄酮、可溶性糖和脯氨酸(Pro)含量,同时也可显著提高幼苗根系活力和超氧化物歧化酶(SOD)活性,显著降低丙二醛(MDA)含量。这说明适宜浓度的抗坏血酸能提高黄芩种子的萌发能力和幼苗对盐胁迫的适应能力,从而起到缓解盐胁迫对种子萌发及幼苗生长的抑制作用。     

外源Ca2+浸种对Cd2+胁迫下红三叶种子萌发和幼苗生长及其生化特性的影响

用不同浓度Ca2 溶液浸种处理红三叶种子后、用0.1 mmol·L-1Cd2 溶液培养,探讨外源Ca2 对Cd2 胁迫下红三叶种子萌发、幼苗生长及其保护酶活性和子叶叶绿素含量的影响.结果显示:(1)0.1 mmol·L-1Ca2 浸种处理能显著缓解Cd2 胁迫的影响,可使红三叶种子发芽势、发芽指数及活力指数显著升高,全苗长、胚根长和胚根/胚芽显著增加(分别增加21.38%、44.06%和38.63%),并显著提高叶绿素含量(14.59%);(2)0.11、.0 mmol·L-1Ca2 浸种预处理均能显著提高Cd2 胁迫下红三叶幼苗子叶SOD活性(43.17%、218.95%)和POD活性(34.00%、14.28%),并显著降低其CAT活性(17.43%、29.19%)和MDA含量(21.92%、24.51%).结果表明,0.1mmol·L-1外源Ca2 浸种处理能显著缓解Cd2 (0.1 mmol·L-1)胁迫对红三叶种子萌发及幼苗生长及其保护酶活性的抑制作用,可明显提高红三叶幼苗对Cd2 胁迫的抵抗能力,缓解效果最优.     

Ca^2＋对小麦萌发及幼苗抗盐性的效应

以冬小麦（Triticum aestivum）临远077038为材料, 研究了施入外源Ca^2＋对150、200、250及350 mmol·L^-1NaCl胁迫下小麦种子萌发及幼苗生长发育的影响。结果表明： 20 mmol·L^-1CaCl2浸种能够提高小麦在150–250 mmol·L^-1盐胁迫下种子的发芽率, 并能增强其生长势; 当NaCl浓度为350 mmol·L^-1时, 小麦种子不能萌发, 且在以上浓度的NaCl胁迫下, 小麦种子均不能发育成苗。对NaCl胁迫下的小麦幼苗施入外源Ca^2＋后, 提高了幼苗膜稳定性, 降低了膜脂过氧化程度, 从而减轻了盐胁迫对幼苗膜的伤害, 表现为电导率降低、MDA含量降低及SOD和POD活性提高, 并且提高了幼苗的呼吸强度及叶绿素含量, 促进了幼苗生长及生物量的积累; Ca^2＋的缓解效应随着盐胁迫的加剧逐渐减弱, 在浓度为350 mmol·L^-1的盐胁迫下, 幼苗的生物量显著低于对照。以上结果表明, 与水处理相比, 20 mmol·L^-1CaCl2处理能够更大程度地促进小麦的生长发育。     

外源水杨酸对盐胁迫下大黄种子萌发及幼苗生长的影响

该研究以掌叶大黄、唐古特大黄和药用大黄种子为材料,采用双层滤纸培养法,设置系列浓度NaCl (0、100、150、200、250 mmol/L) 胁迫试验,以及系列浓度水杨酸(SA)溶液(0、50、100、150、200、250 mg/L)拌种和浸种后盐胁迫实验,测定3种大黄种子萌发及幼苗生长指标,揭示外源水杨酸对盐胁迫下大黄种子萌发及幼苗生长的影响。结果显示：(1)随NaCl浓度增大3种大黄种子的发芽率均呈直线下降趋势,且子叶、胚轴、根和苗等生长均受到强烈抑制。(2)在拌种条件下, 200 mmol/L NaCl胁迫下掌叶大黄苗长在200 mg/L SA处理下受到显著促进; 200 mmol/L NaCl浓度盐胁迫下唐古特大黄种子发芽率在250 mg/L SA处理下受到显著抑制;100 mmol/L NaCl胁迫下药用大黄种子发芽势在200 mg/L SA处理下受到显著抑制,其发芽率在150 mg/L SA处理下得到显著抑制,其苗长在250 mg/L SA处理下受到显著抑制。(3)在浸种条件下, 200 mmol/L NaCl胁迫下掌叶大黄种子发芽率在50 mg/L SA处理下显著提高,其幼苗根长和苗长的生长在250 mg/L SA处理受到显著促进;200 mmol/L NaCl胁迫下唐古特大黄种子的发芽势在200 mg/L SA处理下得到显著促进,其幼苗根和苗的生长在50 mg/L SA处理下得到显著促进;100 mmol/L NaCl 胁迫下药用大黄根和苗的生长在100 mg/L SA处理下均得到显著促进。研究表明,3种大黄种子和幼苗对盐胁迫的响应趋势一致,但对不同浓度SA拌种和浸种的响应有较大差异。     

NaCl胁迫下外源γ-氨基丁酸对黄瓜幼苗生长和活性氧代谢的影响

以黄瓜(Cucumis sativusL.)品种津绿3号为材料,采用营养液水培法,研究了外源γ-氨基丁酸(GABA)对NaCl胁迫下幼苗生长和活性氧(ROS)代谢的影响.结果表明,NaCl胁迫处理显著抑制了幼苗的生长,叶片抗氧化酶活性、活性氧含量显著提高;营养液添加GABA处理不但缓解了NaCl胁迫对幼苗生长的抑制作用,且叶片SOD、POD和CAT活性显著高于NaCl处理,而O-·2产生速率、MDA含量却显著低于NaCl处理;5 mmol·L-1GA-BA处理缓解NaCl胁迫对幼苗伤害的效果好于2.5 mmol·L-1GABA处理.表明NaCl胁迫下,GABA参与了黄瓜幼苗活性氧的代谢过程,对增强幼苗耐盐性有重要作用.     

光照、温度和盐分对长叶红沙种子萌发的影响

无论在光下和暗中长叶红沙种子都能萌发,萌发率无显著差异;种子萌发的适宜温度为20~25℃。温度高于25℃时,温度越高,萌发率越低;浓度低于100mmol·L-1的NaCl对种子萌发的影响不大,但高于150mmol·L-1时,NaCl下的萌发率随着NaCl浓度的增高而下降,直至0;NaCl溶液处理9d的未萌发种子转移至蒸馏水中后,经高浓度NaCl胁迫(小于500mmol·L-1)处理的种子萌发恢复率较高。     

盐胁迫及外源钙处理对盐肤木种子萌发的影响

为研究盐肤木种子萌发的盐胁迫机制和外源钙对盐胁迫下种子萌发的影响,实施不同浓度的NaCl、Na_2SO_4、CaCl_2+NaCl、CaCl_2+Na_2SO_4溶液胁迫处理盐肤木(Rhus chinensis)种子的萌发试验,分析其发芽指标、活力参数和幼苗生长的变化。结果表明:随着盐胁迫溶液NaCl和Na_2SO_4浓度的升高,盐肤木种子的发芽率、发芽势、发芽指数、活力指数和幼苗胚芽及胚根长均表现为不同程度减少的趋势,其中100 mmol/L NaCl、75 mmol/L Na_2SO_4胁迫对盐肤木种子的萌发及幼苗的生长有显著的抑制作用;同胁迫溶液NaCl相比,盐肤木种子萌发过程中对Na_2SO_4危害敏感的浓度范围较小。不同浓度的CaCl_2浸种处理时,盐肤木的盐害缓解作用呈现先升高后降低的趋势,30 mmol/L CaCl_2+100 mmol/L Na Cl和15 mmol/L CaCl_2+75 mmol/L Na_2SO_4浓度下盐胁迫处理的缓解能力最强。该研究结果有利于缓解盐胁迫对于盐肤木种子萌发的盐害。     

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.