氧化钙对水稻幼苗的生理作用研究

利用几种含钙化合物处理土壤后播种水稻,发现氧化钙具有显著的生理活性,土壤中含量在1.0%时明显增加旱育秧水稻幼苗高度、增加根数和加快叶片发育速度。进一步研究发现0.5～1.5％ CaO能够降低稻苗细胞电解质渗透率和脂质过氧化程度,增加叶绿素含量和体内可溶性蛋白含量,并能提高POD活性,增强稻苗抗低温能力。     

硒对镉胁迫下水稻幼苗生长及生理特性的影响

采用溶液培养 ,研究不同浓度的硒和镉处理对稻苗的株高、叶片干重、叶绿素、还原糖、叶片丙二醛含量以及保护酶 SOD、POD、CAT活性的影响。结果表明 ,镉胁迫下稻苗矮化 ,镉毒害使叶片失绿 ,干重降低 ,还原糖含量下降 ,叶片 MDA含量增加 ,POD活性增强 ,而 SOD、CAT活性降低 ;硒可减轻镉对水稻的毒害 ,表现为 :减轻镉胁迫对株高增加的抑制 ,提高叶绿素含量 ,增加叶片干物质积累 ,提高叶片还原糖含量 (Cd0 .5 mg/ L加 Se 0 .1 0～ 0 .5 0 mg/ L例外 ) ,降低 MDA含量与 POD活性 ,提高 SOD、CAT活性     

水稻覆膜旱作对根叶性状、土壤养分和土壤微生物活性的影响

研究了水稻覆膜旱作、裸地旱作、常规水作处理对根系形态、叶片水势、土壤养分、土壤微生物数量和土壤酶活性的影响。结果表明,覆膜旱作能改善水稻田间的生态环境,提高早季土壤温度1～3℃。与裸地旱作相比,覆膜旱作能增加抽穗期水稻根系的总根长、比根长,而这些指标与常规水作差别不大。在水稻抽穗期,无论是剑叶还是倒2叶的水势,均有如下趋势：水作〉覆膜旱作〉裸地旱作,但均未达到显著水平。不同处理对叶片叶绿素含量的影响在分蘖期差异不大,中后期覆膜旱作明显高于裸地旱作和常规水作,抽穗期分别增加29．44％和15．15％,成熟期则为74．4％、38．9％。覆膜旱作能显著增加水稻的有效穗数,早季和晚季产量比裸地旱作增产10．6％和12．5％,而与常规水作差别不大。与裸地旱作和常规水作相比,覆膜旱作土壤养分含量在分蘖期除了全磷、速效氮显著增加外,其他指标差异不大。而抽穗期则由于覆膜后作物对养分的消耗加大从而使土壤养分含量下降,特别是总磷、速效磷、速效钾与常规水作相比显著下降,分别降低25．9％,31．9％,16．2％。而成熟期则大多指标与常规水作相比有所下降,但未达到显著水平。与常规水作栽培相比,覆膜旱作能增加土壤微生物细菌、真菌、放线菌2．5倍,显著增加土壤过氧化氢酶和蔗糖酶的活性,而土壤脲酶活性则差异不大。土壤过氧化氢酶活性在分蘖期、抽穗期、成熟期分别增加13．8％,81．3％,17．4％,蔗糖酶活性则分别增加42．8％,28．8％和69．9％。     

贵州特有植物美丽红山茶水分胁迫的生理响应

采用水分抗逆性指标主成分分析法,选择4年实生苗,测定和评价了连续30 d水涝和干旱胁迫的生理响应.结果表明：(1)水涝处理的叶片生长旺盛,光泽度和观赏性无明显变化,叶片相对含水量、MDA含量、SOD活性、POD活性、CAT活性的变化差异在5％以内,土壤含水量增加3．47％,细胞膜透性减少1．59％,短期水涝对美丽红山茶伤害不明显;(2)随着干旱时间延长,新叶卷缩、老叶脱落,土壤含水量、叶片相对含水量随时间呈负相关缓慢减少,细胞膜透性呈正相关缓慢增长,但复水10 d 后可恢复正常生长,无明显生理变化响应;(3)SOD活性和MDA含量分别增加了0．66％和5．31％,POD活性随干旱时间上下波动而增加6．47％, CAT活性随干旱时间延长而增加,20 d增加33．33％达最大值20．8 U??g-1??min-1.在抗性生理中,维持膜稳定性的叶片含水量、POD和CAT的变化对抗旱能力大小起主要作用.     

鸡粪对铜污染土壤微生物生物量碳的影响

采用室内恒温好气培养法,研究了2．0％、4．0％、6．0％添加量鸡粪对铜污染土壤微生物生物量碳的影响。结果表明：向土壤中施入2．0％、4．0％、6．0％的鸡粪后,有机碳总量比对照分别增加了0．85、1．49、2．04倍,而可浸提有机碳含量分别增加了3．13、5．70、8．23倍,鸡粪的添加促进了土壤可浸提有机碳含量的增加,土壤可浸提有机碳含量和鸡粪添加量呈正相关（r=0．994^＊＊,n=12）。各处理土壤有机碳和可浸提有机碳含量随培养时间逐渐下降,90d后有机碳含量趋于稳定;土壤可浸提有机碳含量120d后趋于稳定。鸡粪显著促进了土壤微生物生物量碳含量和土壤微生物商的增加（P〈0．01）,与对照相比,2．0％、4．0％和6．0％鸡粪处理土壤微生物生物量碳含量分别增加2．88、5．19、6．98倍,土壤微生物生物量碳（SMBC）含量和土壤微生物商（SMQ）都与鸡粪的添加量呈正相关（rSMBC=0．998^＊＊,rSMQ=0．858,n=12）。在培养过程中士壤微生物生物量碳与土壤微生物商都呈现先下降再升高再下降的趋势。在培养试验的早期,鸡粪的添加有利于缓解铜污染土壤微生物生物量碳的下降,添加鸡粪的处理在培养的第10d后土壤微生物生物量碳含量开始上升,而对照则在30d以后才开始上升;添加鸡粪的处理在培养前期微生物生物量碳的最大下降幅度分别为：2．0％处理（52．74％）、4．0％处理（45．92％）、6．0％处理（55．52％）,而对照的下降幅度为92．02％。培养后期添加鸡粪处理土壤微生物生物量碳仍保持较高的水平。     

水稻和稗草共生土壤微生物生物量碳及酶活性的变化

以稻田稗草、化感水稻PI312777和普通水稻辽粳9为试材,研究了田间稗草和水稻1∶1共生条件下,土壤微生物生物量碳及脱氢酶、脲酶和转化酶活性的变化.结果表明：在稗草 的干扰下,化感水稻PI312777根区土壤微生物生物量碳含量比单作减少了 50.52％（P<0.01）,而行间土壤微生物生物量碳含量增加;普通水稻辽粳9根区土壤 微生物生物量碳含量比单作减少了38.99％（P<0.01）,但其行间土壤微生物生物量碳含量无明显变化.两个水稻品种根区土壤脱氢酶活性均被显著抑制（P<0.05）,下降率都在20％以上;PI312777根区土壤脲酶和转化酶活性均被显著促进（P<0.01）;而辽粳9根区土壤转化酶活性也被显著抑制（P<0.01）,但脲酶活性无明显变化.化感水稻根区土壤微生物生物量碳含量的显著减少及脲酶、转化酶活性的增加是其化感特性的表现,表明土壤微生物和酶均参与了水稻和稗草的种间作用,化感水稻具有抗稗草干扰的明显优势.     

稻田免耕和稻草还田对土壤腐殖质和微生物活性的影响

为了阐明免耕和稻草还田土壤固碳机制,研究了无稻草还田免耕（NT）、无稻草还田常耕（CT）、稻草还田免耕（NTS）和稻草还田常耕（CTS）对水稻不同生育期不同土层（0—5,5—12,12—20cm）土壤腐殖质形态、含量及微生物活性的影响。结果表明,免耕（NT和NTS）处理显著增加0—5 cm土层土壤游离松结态、联结态和稳紧结态腐殖质含量和游离松结态腐殖质占总腐殖质的比例,且免耕对土壤各结合态腐殖质含量的影响程度有随生育期的推后而增加的趋势;5—12cm和12—20cm土层土壤各结合态腐殖质含量和0—20cm各土层微生物活性有减少趋势;在水稻分蘖期免耕对微生物活性影响很弱,在水稻拔节—灌浆期免耕处理显著降低5—12 cm土层土壤微生物活性,相反,免耕却增加水稻成熟期0—5 cm土层的微生物活性;另一方面,稻草还田（CTS和NTS）显著提高土壤各结合态腐殖质含量,尤其是0—5 cm土层、游离松结态腐殖质及水稻生育后期;CTS处理显著增加分蘖期—孕穗期0—20 cm土层的呼吸强度,而稻草还田显著增加孕穗期—成熟期0—5cm土层的纤维素分解强度。可见,通过增加土壤腐殖质含量和各结合态腐殖质含量并改变微生物活性免耕有利于表土层碳的固定作用,而免耕与稻草还田相结合更有利于土壤碳的积累。     

秸秆预处理对土壤微生物量及呼吸活性的影响

冬小麦秸秆经8．0g·L^-1H2O2(pH11．0)溶液、12．5g·L^-1 NaOH溶液或H2SO4溶液浸泡8h并80℃烘干后,与无机N一起加入土壤,进行室内25℃恒温培养试验,在不同时间测定土壤微生物量C、N和CO2释放速率。结果表明,培养前期,秸秆预处理使土壤微生物量C数量增加了1．0～1．4倍,但降低了土壤微生物的呼吸活性;培养后期,NaOH和H2SO4处理使土壤微生物量C分别下降了28％和42％,但增加了土壤微生物的呼吸活性;H2O2处理则使土壤微生物量N增加90％;土壤微生物区系中的真菌比例在不同时刻有所增加,表明将秸秆预处理后施入土壤,将对土壤中微生物数量和呼吸活性产生一定影响。     

盐胁迫下镧对水稻幼苗生长的保护效应

通过液培实验,研究水稻幼苗在盐胁迫下,镧对水稻幼苗的保护作用。结果表明：水稻幼苗植株在≤1．5％的盐浓度的盐胁迫下,10mg·L^-1镧能提高幼苗植株超氧化物歧化酶（SOD）和过氧化氢酶（CAT）的活性;降低幼苗植株脂质过氧化产物丙二醛（MDA）的含量和脯氨酸（Pro）的含量;减小质膜透性;提高叶片叶绿素含量和叶绿素a／b的比值;增强根系的活力,进而促进水稻幼苗的生长。10mg·L^-1镧对盐胁迫的缓解作用与盐浓度有关,随着盐浓度增大,镧的缓解作用将逐渐消失。分析表明,在≤1．0％和≥0．5％的盐浓度胁迫下,镧对水稻幼苗的生长存在更有效的防御机制,能够促进水稻幼苗的生长代谢。     

杉木与阔叶树叶凋落物混合分解对土壤活性有机质的影响

通过室内培养,研究了杉木叶凋落物及与桤木、刺楸和火力楠混合叶凋落物对土壤活性有机质的影响．结果表明：添加叶凋落物显著地增加了土壤微生物碳、氮及土壤呼吸强度和可溶性有机碳含量．其中,添加杉-阔混合叶凋落物对土壤活性有机质的增加效应大于纯杉木叶凋落物．在培养后期（第135天）,添加纯杉木叶凋落物和杉-阔混合叶凋落物处理土壤微生物碳含量分别比对照土壤高49％和63％,微生物氮高35％和75％,土壤呼吸强度高65％和100％,可溶性有机碳含量高66％和108％．添加叶凋落物对土壤微生物熵和微生物C／N的影响不显著（P〉0．05）．     

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.