华南地区2种优质牧草对入侵杂草薇甘菊的化感作用

研究了2种牧草大翼豆和旋扭山绿豆,以及入侵杂草薇甘菊的化感作用。结果表明,化感作用大小表现为:大翼豆〉薇甘菊〉旋扭山绿豆。大翼豆对薇甘菊具有化感抑制作用,其中茎的抑制作用大于叶,高浓度的抑制作用大于低浓度。旋扭山绿豆对薇甘菊的化感抑制作用显著低于大翼豆。另一方面,薇甘菊对2种牧草的化感作用较弱,远低于2种牧草对薇甘菊的抑制作用。可见,果园间作牧草大翼豆比旋扭山绿豆在防止薇甘菊入侵方面更具有优势。     

西北黄芪和山野豌豆对低温胁迫的生理响应研究

以两种野生豆科牧草(西北黄芪和山野豌豆)为试验材料,研究其对低温胁迫的生理响应。结果表明:在低温胁迫下,西北黄芪和山野豌豆的相对电导率、SOD活性、可溶性糖含量、脯氨酸含量均表现出上升的趋势,且随着低温胁迫程度的加剧而加深;就相对电导率、可溶性糖含量两项生理指标而言,西北黄芪5℃增幅显著小于山野豌豆,而-5℃对5℃增幅显著大于山野豌豆;就脯氨酸含量而言,西北黄芪5℃增幅大于山野豌豆,而-5℃对5℃增幅显著小于山野豌豆;就SOD活性而言,西北黄芪5℃增幅大于山野豌豆,而-5℃对5℃增幅显著大于山野豌豆。综合分析,认为西北黄芪比山野豌豆具更强的抗低温能力,同时说明,两种牧草对低温胁迫的生理响应规律不同,相对电导率和可溶性糖含量两项生理指标对低温的响应更加敏感。     

盐胁迫对大米草幼苗某些生理指标的影响

研究了大米草幼苗在不同培养盐度(0、20、30、50、100mmol/LNaCl)下,MDA、游离脯氨酸、可溶性糖、可溶性蛋白质含量以及保护酶(SOD、POD、CAT)活性等生理指标的变化情况。结果表明:保护酶(SOD、POD、CAT)活性在盐胁迫40d前逐渐上升且达显著差异。随着胁迫时间延长,MDA含量与CK相比逐渐降低。随着盐分胁迫浓度的增加及盐胁迫时间延长,大米草叶片中游离脯氨酸、可溶性糖、可溶性蛋白质含量呈上升趋势。在盐胁迫下,渗透调节物质的积累作用是大米草对盐胁迫的主要响应过程,其体内的抗氧化保护酶在此过程中也发挥了重要的作用。     

盐和温度胁迫对外来种互花米草(Spartina alterniflora)生理生态特性的影响

盐浓度和环境温度是影响外来种互花米草自然分布的两大重要生态因子。在不同NaCl浓度和温度胁迫条件下,对互花米草幼苗根部和叶片中膜脂过氧化产物丙二醛(MDA)、游离脯氨酸及可溶性糖、超氧化物歧化酶(SOD)、过氧化物酶(POD)、过氧化氢酶(CAT)的动态变化进行了测定。结果表明:当NaCl浓度低于100mmol·L-1时,可以促进互花米草的生长;而NaCl浓度超过100mmol·L-1时,互花米草可以通过提高体内保护酶(SOD、POD、CAT)活性,增加可溶性糖和游离脯氨酸含量来适应外界盐浓度变化;温度胁迫后,互花米草地上和地下器官对胁迫的响应程度不同,叶片中可溶性糖含量、CAT活性明显比根部高,而根部SOD、POD活性比叶片中高。     

樟子松和油松根叶对春季干旱胁迫的响应

以成年樟子松和油松为对象,分析春季干旱胁迫对叶片和根系形态和生理特性的影响,比较2个树种在干旱胁迫下的响应程度和受伤害大小。结果表明:樟子松叶片含水量、脯氨酸含量、POD和CAT活性均显著高于油松(P0.05),根系活力、含水量、可溶性蛋白和脯氨酸含量及CAT活性、比根长和比表面积均显著高于油松(P0.05)。樟子松叶片丙二醛含量显著低于油松(P0.05),而根系丙二醛含量显著高于油松(P0.05)。可溶性糖和脯氨酸含量及SOD活性在叶片中显著大于根系(P0.05),可溶性蛋白含量及CAT活性在樟子松叶片中显著小于根系(P0.05),POD活性在油松叶片中显著低于根系(P0.05)。上述结果表明,春季干旱胁迫下,樟子松比油松做出了更积极的响应,叶片和根系的响应关系不对应,干旱胁迫对油松叶片伤害更大,而对樟子松根系伤害更大。     

成年侧柏和刺槐对春季干旱的适应策略

本研究以成年侧柏和刺槐为对象,分析春季干旱胁迫对叶片、根系形态和生理特性的影响,比较2树种在干旱胁迫下的适应策略。结果表明:春季干旱胁迫下,侧柏叶片脯氨酸和可溶性蛋白含量及SOD和POD活性显著低于刺槐叶片(P0.05),可溶性糖含量和CAT活性显著高于刺槐叶片(P0.05),两树种叶片丙二醛含量无显著差异(P0.05);侧柏根系脯氨酸和可溶性蛋白含量及POD和CAT活性显著低于刺槐根系(P0.05),可溶性糖和丙二醛含量显著高于刺槐根系(P0.05)。侧柏比叶重和根系活力显著高于刺槐(P0.05),刺槐根长密度和根面积指数显著高于侧柏(P0.05)。这说明春季干旱胁迫下成年侧柏和刺槐的渗透调节物质含量及抗氧化酶活性不同,春季干旱对两树种叶片伤害程度相似,而对侧柏根系伤害更大;成年侧柏主要采取耐旱策略,刺槐主要采用避旱策略。     

高寒牧草在不同温度和盐胁迫作用下的生理生化响应

测定高寒牧草垂穗披碱草(Elymus nutans)和老芒麦(Elymus sibiricus)幼苗在4 个不同浓度的NaCl 溶液(0、50、150、250 mmol·L–1)与6-15 ℃和15-25 ℃两种温度处理条件下的生理生化反馈机制。结果表明: ①垂穗披碱草随着盐浓度的提高, 可溶性糖含量呈现先低后高的趋势; 在盐浓度为Na50 时, 可溶性糖含量最低, 且不同温度处理对垂穗披碱草可溶性糖含量影响不大; 但在高盐浓度(Na150、Na250)处理下, 温度对幼苗可溶性糖含量影响极显著, 6-15 ℃处理显著提高垂穗披碱草幼苗的可溶性糖含量。②随着盐浓度增加, 两种牧草游离脯氨酸含量均迅速积累, 且15-25 ℃处理下脯氨酸含量显著高于6-15 ℃处理。③除垂穗披碱草在Na250 下SOD 酶活性达到最高外, 垂穗披碱草CAT 活性和老芒麦SOD、CAT 活性均随着盐浓度的增加呈现先增加后降低的趋势。表明在一定盐浓度下, 牧草借助抗氧化酶来清除胁迫产生的活性氧, 但高盐浓度在一定程度上抑制了牧草抗氧化酶活性, 而6-15 ℃温度处理可诱导牧草抗氧化酶活性的提高, 尤其是老芒麦。④盐胁迫导致两种牧草根尖过氧化氢含量和细胞死亡率的增加, 而6-15 ℃温度处理可以降低根尖过氧化氢的积累。两种牧草随盐浓度增加根尖细胞死亡率均有增加的趋势, 但6-15 ℃低温可以有效减轻盐胁迫对根细胞的损伤。     

水分和氯化钙胁迫对麦冬抗逆性生理指标的影响

为研究麦冬在水分胁迫和盐分胁迫条件下一些抗逆性生理指标的变化,本文以盆栽后以正常浇水处理为对照,设置了不同程度人工水分胁迫和钙离子胁迫处理研究可溶性糖含量、脯氨酸含量及丙二醛含量的变化情况.结果显示,轻度水分胁迫使可溶性总糖和游离脯氨酸含量减低.但随着时间的推移,胁迫程度加剧,可溶性总糖和游离脯氨酸含量开始回升,而MDA含量无显著变化.表明水分胁迫下.麦冬可积累可溶性糖和游离脯氨酸等渗透调节物质,从而改善自身水分状况,保护细胞膜及生理代谢过程,膜脂过氧化程度减轻.钙盐胁迫也可使可溶性总糖和游离脯氨酸含量升高.     

5-氨基乙酰丙酸对辣椒植株低温胁迫伤害的缓解效应

以‘超越五号'辣椒品种为试材,研究了低温胁迫期间及随后的常温恢复过程中5-氨基乙酰丙酸(ALA 25 mg·L-1)处理对始花期辣椒植株生长量,叶片中脯氨酸、可溶性糖、可溶性蛋白含量,超氧化物歧化酶(SOD)、过氧化物酶(POD)、过氧化氢酶(CAT)、抗坏血酸过氧化物酶(APX)活性和电解质渗透率及丙二醛(MDA)含量的影响,以探讨ALA提高辣椒抗寒性的生理机制.结果表明,低温胁迫下叶面喷施25 mg·L-1的ALA可显著提高辣椒植株生长量,增加叶片中脯氨酸、可溶性糖及可溶性蛋白含量,增强其POD、CAT及APX活性,并显著降低辣椒叶片中SOD活性、电解质渗透率和MDA含量.叶面喷施ALA也显著降低了恢复过程中辣椒叶片中的渗透调节物质含量和抗氧化酶活性,使膜伤害基本恢复到对照水平.可见,外源ALA处理可通过提高低温胁迫下辣椒叶片的渗透调节能力和抗氧化能力,促进植株生长,缓解低温胁迫对植株的伤害.     

低温胁迫对澳洲茶树组培苗生理特性的影响

为探讨澳洲茶树组培苗耐受低温的能力及对低温胁迫的响应机制,该文测定了3月龄澳洲茶树组培苗低温处理过程及恢复培养后叶片叶绿素(Chl)、丙二醛(MDA)、抗氧化物酶(SOD,POD,CAT)、抗坏血酸(AsA)、谷胱甘肽(GSH)、可溶性糖(SS)、可溶性蛋白(SP)、游离脯氨酸(Pro)的变化。结果表明:(1)-5℃胁迫24 h,保护酶及抗氧化物含量均显著下降,MDA含量显著上升。(2) 0℃下,AsA和GSH先降后升,POD和CAT相反,SOD持续升高;胁迫48 h后保护酶活性显著升高,抗氧化剂含量显著降低。(3) 10℃下,SOD活性先降后升;胁迫48 h后,渗透调节物质含量均显著升高。因此,3月龄澳洲茶树组培苗在-5℃受到致死冻害,幼苗能通过启动抗氧化系统及快速积累渗透调节物质响应0℃以上低温胁迫,但对10℃和0℃两种低温胁迫的应答机制却存在一定的差异。该研究结果将有助于深入了解其对低温的耐受能力及生理响应机制,为合理引种及规模化种植提供理论依据。     

Systematic significance of mature embryo of bamboos

The mature embryo of seven species belonging to five genera of Indian bamboos is described. In all these the basic pattern of embryo organisation is same: the scutellar and coleoptilar bundles are not separated by an internode, the epiblast is absent, the lower portion of the scutellum and the coleorhiza are separated by a cleft and the margins of embryonic leaves overlap. The features unique to fleshy fruited bamboos are: presence of a massive scutellum, the juxtaposition of plumule and radicle and the occurrence of a bud in the axil of the coleoptile. The fleshy fruit bearing bamboos should be classified into one group, the tribeMelocanneae. Evidence is provided to recognise additional groups in the subfamilyBambusoideae.     

Taxonomic status of the species of the green algal genusNeochloris

Komárek has recently reviewed the various species assigned to the green algal genusNeochloris Starr (Chlorococcales, Chlorococcaceae) and removed those with uninucleate vegetative cells to a new genus,Ettlia. Watanabe & Floyd, unaware ofKomárek's work, also reviewed the species ofNeochloris and distributed them among three genera—Neochloris, Chlorococcopsis gen. nov., andParietochloris gen. nov.—on the basis of details of the covering of the zoospore and the arrangement of the basal bodies of the flagellar apparatus. This paper reconciles these two treatments and makes additional recommendations at the ranks of genus, family, order, and class.     

Analysis of twin of eyeless regulation during early embryogenesis in Drosophila melanogaster

The Drosophila Pax6 homolog twin of eyeless (toy) is so far the first zygotically expressed gene involved in eye morphogenesis in Drosophila. The study of its expression during embryogenesis is therefore informative of the initial events of eye development in Drosophila. We have analyzed how the initial expression domain of toy at cellular blastoderm is regulated. We show that the three maternal patterning systems active in the cephalic region (the anterior, terminal and dorsal-ventral systems) cooperate with zygotically activated gap genes to shape the initial expression domain of toy. Whereas Bicoid, Dorsal and Torso signaling synergistically act as activators, Hunchback, Knirps and Decapentaplegic act as repressors.     

Apoptotic Regulation of Caspase Activity

Intracellular cysteine aspartate-specific proteases (caspases) play both signaling and effector roles in realizing the program of cell death. Caspases function as proteolytic cascades unique for each cell type and signal triggering apoptosis. All parts of the proteolytic cascades are duplicated and controlled by feedback signals. Amplification cycles between pairs of caspases (the third and the sixth, the ninth and the third, the twelfth and the sixth, and others) help multiply the initial apoptotic signal. The presence of physiological inhibitors of apoptosis that directly interact with caspases creates a multilevel regulatory network of apoptosis in cell. The caspase proteolytic cascades are also regulated by sphingolipid secondary messengers, among them ceramide, sphingosine, and their phosphates. Moreover, an association of the caspase signaling with ubiquitin-dependent proteolysis is shown in cells. In particular, the use of extracellular activators and inhibitors of caspases allows irreversible activation of apoptosis in tumor cells or the prevention of apoptosis in cortical neurons under neurodegenerative diseases.     

广西青藓科分类学修订

通过对采自广西24个县(市)的1 147份青藓科植物标本的逐一鉴定及相关文献的查阅,确认有广西青藓科植物11属、44种,其中包括广西青藓科植物新记录属1属,即拟异叶藓属(Pseudokindbergia),新记录种7种,分别为匐枝青藓(Brachythecium procumbens)、阔叶尖喙藓(Oxyrrhynchium latifolium)、泛生尖喙藓(O. vagans)、拟异叶藓(Pseudokindbergia dumosa)、华东细喙藓(Rhynchostegiella sinensis)、长肋拟青藓(Sciurohypnum populeum)和弯叶拟青藓(S. reflexum)。该文提供了修订后的广西青藓科植物名录,并对其中的新记录属、种的主要形态学识别特征、生境和地理分布等进行了详细描述。     

The effect of cyanobacteria and azolla on the performance of rice under different levels of fertilizer nitrogen

Cyanobacteria and/or azolla were inoculated, with urea at 0, 72 or 144 kg N/ha, in plots in which azolla-free Indica rice var. IR 28 was grown. Productive tillers, yield and nitrogen contents of grain and straw positively responded to inoculation with cyanobacteria or azolla, even with fertilizer-N up to 144 kg N/ha. Inoculation improved colonization by cyanobacteria. Azolla were superior to the asymbiotic cyanobacteria in enhancing rice performance. Urea at a rate of 72 kg N/ha was found to support the best colonizations when applied with cyanobacteria or azolla or, to give maximum rice yields, both inoculants.     

Phylogeny of cardinalfishes (Teleostei: Gobiiformes: Apogonidae) and the evolution of visceral bioluminescence

The cardinalfishes (Apogonidae) are a diverse clade of small, mostly reef-dwelling fishes, for which a variety of morphological data have not yielded a consistent phylogeny. We use DNA sequence to hypothesize phylogenetic relationships within Apogonidae and among apogonids and other acanthomorph families, to examine patterns of evolution including the distribution of a visceral bioluminescence system. In conformance with previous studies, Apogonidae is placed in a clade with Pempheridae, Kurtidae, Leiognathidae, and Gobioidei. The apogonid genus Pseudamia is recovered outside the remainder of the family, not as sister to the superficially similar genus Gymnapogon. Species sampled from the Caribbean and Western Atlantic (Phaeoptyx, Astrapogon, and some Apogon species) form a clade, as do the larger-bodied Glossamia and Cheilodipterus. Incidence of visceral bioluminescence is found scattered throughout the phylogeny, independently for each group in which it is present. Examination of the fine structure of the visceral bioluminescence system through histology shows that light organs exhibit a range of morphologies, with some composed of complex masses of tubules (Siphamia, Pempheris, Parapriacanthus) and others lacking tubules but containing chambers formed by folds of the visceral epithelium (Acropoma, Archamia, Jaydia, and Rhabdamia). Light organs in Siphamia, Acropoma, Pempheris and Parapriacanthus are distinct from but connected to the gut; those in Archamia, Jaydia, and Rhabdamia are simply portions of the intestinal tract, and are little differentiated from the surrounding tissues. The presence or absence of symbiotic luminescent bacteria does not correlate with light organ structure; the tubular light organs of Siphamia and chambered tubes of Acropoma house bacteria, those in Pempheridae and the other Apogonidae do not.     

Evaluation of antiprotozoal and antimycobacterial activities of the resin glycosides and the other metabolites of Scrophularia cryptophila

Resin glycosides are secondary metabolites exclusive to the convolvulaceous plants. In this study, crypthophilic acids A–C (1–3), the first resin glycosides occurring in another family (Scrophulariaceae), and the other constituents of Scrophularia cryptophila were examined for in vitro antiprotozoal and antimycobacterial potentials. Except for crypthophilic acid B (2), all tested compounds exhibited growth-inhibitory effect against Trypanosoma brucei rhodesiense, with l-tryptophan (6) and buddlejasaponin III (7) being the most potent ones (IC₅₀'s 4.1 and 9.7 μg/ml). In contrast, the activity towards Trypanosoma cruzi was poor, and only crypthophilic acid C (3), 6 and 7 were trypanocidal at concentrations above 40 μg/ml. With the exception of 2 and 6, all compounds were active against Leishmania donovani. Harpagide (4) and 3 emerged as the best leishmanicidal agents (IC₅₀'s 2.0 and 5.8 μg/ml). Only compounds 3, 6 and 7 showed antimalarial activity against Plasmodium falciparum with IC₅₀ values of 4.2, 16.6 and 22.4 μg/ml. Overall the best and broadest spectrum activity was presented by compounds 3 and 7, as they inhibited all four parasitic protozoa. None of the isolates had significant activity against Mycobacterium tuberculosis (MICs >100 μg/ml) or were toxic towards mammalian (L6) cells. This is the first report of antiprotozoal activity for natural resin glycosides, as well as for harpagide (4), acetylharpagide (5), tryptophan (6) and buddlejasaponin III (7).     

New species of Peruvian Orchidaceae III

Sixteen new species are proposed in the generaAckermania, Dressleria, Epidendrum, Maxillaria, Oncidium, Rodriguezia, Sigmatostalix, andTrigonidium. All new species are illustrated.Maxillaria vittariifolia L. O. Williams is newly recorded for Peru. A key is provided forTrigonidium of Peru.Trigonidium loretoense Schltr. andT. peruvianum Schltr. are lectotypified.