青海云杉(Picea crassifolia)种群格局的分形特征及其影响因素

应用计盒维数、信息维数和关联维数对祁连山主要森林类型青海云杉(Picea crassifolia)种群空间格局进行的研究表明:青海云杉种群格局计盒维数在0.992～1.938之间,平均值为1.716,信息维数在0.996～1.860之间,平均值为1.632, 关联维数在1.418～1.759之间,平均值为1.568.计盒维数与样地海拔和土壤水分含量呈显著的负相关,与样地坡向呈显著的正相关,信息维数与样地海拔呈显著负相关而与坡向呈显著的正相关,关联维数与样地坡度呈显著的负相关,主成分分析表明,海拔和土壤含水量是影响青海云杉种群格局分形维数第一主成分,坡向是第二主成分,坡度是第三主成分,这3个主成分累计解释率为87.6%.     

元宝山南方红豆杉克隆种群分布格局的分形特征

南方红豆杉(Taxus chinensis var. mairei)是提取抗癌药物紫杉醇的珍贵资源植物。分布于广西元宝山自然保护区的南方红豆杉,自然状态下以克隆繁殖方式进行种群更新,研究其种群克隆生长的空间分布格局,可揭示种群克隆繁殖特性和生态适应机制,对南方红豆杉这一珍稀濒危物种的保护和管理具有重要意义。利用分形理论中的计盒维数和信息维数,对元宝山的南方红豆杉克隆种群空间分布格局的分形特征进行了分析,结果表明:种群空间分布格局存在分形特征,其计盒维数介于0.993 1~1.353 1之间,信息维数介于1.350 8~1.652 1。南方红豆杉克隆种群格局的计盒维数远离最大理论维数值2,种群总体对空间的占据能力较弱。克隆构型指数与种群计盒维数密切相关。分析结果显示,克隆构型趋于“密集型”的种群具有较强的空间占据能力,而克隆构型趋于“游击型”的种群其空间占据能力较弱。信息维数与种群的集聚强度密切相关,其差异反映了种群格局强度的变化,较大的信息维数反映种群个体的集聚强度较高,而较小的信息维数则反映出种群个体间的集聚强度较弱,其维数值大小与分株种群数量、分株种群斑块的空间配置密切相关。     

涪陵磨盘沟自然保护区桫椤种群分布格局的分形特征

利用分形理论中的计盒维数探讨了重庆市涪陵磨盘沟桫椤种群的分形特征。结果表明,桫椤种群的分布格局具有分形特征。桫椤种群在不同海拔高度分布格局的计盒维数各不相同,与生境密切相关。在6个不同植物群落中,桫椤种群的计盒维数大小依次为黄牛奶树淡竹叶>黄杞水麻>盐肤木腹水草>血桐芒>白栎扁穗莎草>毛叶木姜子火炭木。计盒维数定量地反映了该自然保护区桫椤种群占据生态空间的能力,随机型的桫椤种群对空间占有能力比聚集型的低。     

云贵鹅耳枥种群分布格局的分形特征

应用分形理论中的计盒维数和信息维数探讨了贵阳喀斯特山地贵鹅耳枥种群分布格局的分形特征。结果表明,贵鹅耳枥种群的分布格局具有分形特征,其计盒维数为1．1853－1．7419,信息维数为1．1961－1．7051。集群型的贵鹅耳枥种群的计盒维数和信息维数均比随机型的高。计盒维数定量地反映了贵鹅耳枥种群占据生态空间的能力,信息维数则揭示了该种群格局强度的尺度变化程度和表征了种群个体分布的非均匀性。这两种维数方法都适用于贵鹅耳枥种群分布格局分形特征的定量描述。     

秦岭太白红杉种群空间分布格局动态及分形特征研究

采用相邻格子样方法采集数据,应用计盒维数和信息维数研究了太白红杉种群空间格局的分形特征,结果表明,太白红杉种群有较高的计盒维数(1.8087)和信息维数(1.7931),表明其对空间占据程度较高.用分布系数法和Morisita格局指数法检验格局类型,发现不同年龄组太白红杉种群均呈聚集分布.运用Greig-Smith的方法研究格局规模,发现太白红杉种群在128m²和512m²处聚集,不同年龄组在不同规模尺度聚集.以区组分布格局强度(PI)检测聚集强度,发现太白红杉种群格局强度随尺度变化程度较高,个体分布不均匀,随着年龄的增大,其聚集强度呈下降趋势.太白红杉种群的空间分布格局特征是其对严酷生境长期适应的结果.     

不同类型群落中濒危植物永瓣藤 (Monimopetalum chinense) 种群的空间分布格局

为揭示永瓣藤(Monimopetalum chinense)种群的分布格局特征及其成因,采用分形分析中的计盒维数对取自4个分布地的13个样方进行了研究.结果显示:(1) 同一研究地不同群落中永瓣藤种群的分形特征差异明显,而不同研究地同一类型群落之间的差异不大,分析认为这与永瓣藤在群落中的生态地位及生境异质性有关.(2) 永瓣藤种群计盒维数由高到低依次为杉木林 (1.911±0.025)、杂木林 (1.806±0.079)、马尾松林 (1.692±0.054) 和毛竹林 (1.629±0.081),表明不同群落中其个体分布的非均匀性存在较大差异.(3) 永瓣藤种群的拐点尺度由高到低依次为毛竹林 (4.111 m±0.484 m)、马尾松林 (3.778 m±0.222 m)、杂木林 (2.857 m)、杉木林 (2.013 m±0.117 m),次序与计盒维数相反.(4) 分析认为,不同群落中永瓣藤无性繁殖能力的不同对其种群格局的计盒维数以及拐点尺度有重要影响.     

宁夏珍稀濒危植物半日花种群结构和点格局分析

半日花是国家二级珍稀濒危植物,其种群数量日益减少,分布区破碎化。以宁夏新记录物种半日花为研究对象,分析在沙地和砾石质两种生境下半日花种群结构、各龄级的空间分布格局及关联性。结果表明: 宁夏青铜峡地区半日花个体主要集中在龄级Ⅲ,种群年龄结构呈倒三角形,种群正在衰退。种群空间分布格局与不同龄级间空间关联性受生境条件的影响较大,并且对空间尺度表现出很强的依赖性,与沙地生境相比,砾石质生境中半日花种群更趋向于聚集分布,各个龄级之间的正相关性也更明显,这种差别与两种生境的环境条件和群落结构有关。半日花种群中幼龄个体(龄级Ⅰ和龄级Ⅱ)具有相互依赖的生态关系。     

天然黄山松种群格局的分形特征——计盒维数与信息维数

采用计盒维数和信息维数对屏南和寿宁不同群落的天然黄山松(Pinus taiwanensis)种群格局的分形特征进行比较分析.结果表明,天然黄山松种群格局具有分形特征,其计盒维数值在1.299 8～1.862 6之间,不同群落的大小次序为Q3>Q1>Q2>Q4>Q7>Q8>Q5>Q6;信息维数值在1.205 7～1.863 7之间,大小次序是Q3>Q1>Q2>Q4>Q8>Q7>Q5>Q6,屏南天然黄山松近纯林黄山松种群的计盒维数和信息维数均高于寿宁混交林,计盒维数定量描述种群占据水平空间的能力和程度,信息维数揭示种群格局强度的尺度变化及个体分布的非均匀程度,分形维数值的高低与群落环境、种群密度、种群在群落中的优势地位、个体的聚集程度及幼树个体数量等相关.黄山松种群格局分形维数随海拔呈现上下波动变化,1 250～1 270 m是更适生的海拔范围.此外,黄山松种群格局的分形特征存在一定的尺度范围,其拐点尺度是分形范围的下限尺度.     

兴安落叶松种群格局的分形特征:计盒维数

分形维数是分形体填充空间程度的度量,种群格局计盒维数能够揭示出种群格局的空间占据程度及其尺度变化规律,拐点尺度指示出个体聚集尺度。本文应用计盒维数对大兴安岭主要森林类型中兴安落叶松种群空间格局进行的研究表明,兴安落叶松种群格局均具有统计自相似性。各类兴安落叶松林中兴安落叶松种群格局具有较高的计盒维数(> 1.5,接近2),对空间占据程度较高,建群和优势地位明显,空间占据程度的强弱次序为越桔-兴安落叶松(1.829) > 草类-兴安落叶松林(1.720) > 杜鹃-兴安落叶松(1.705)杜香-兴安落叶松林(1.513)。兴安落叶松-白桦林中,兴安落叶松处于劣势伴生地位,种群格局的计盒维数较低(1.371,远离2),空间占据程度低。通过对天然森林类型中兴安落叶松种群格局的计盒维数与兴安落叶松人工林的比较发现,兴安落叶松种群空间占据程度由高至低的次序为兴安落叶松人工林(1.868) > 兴安落叶松天然林(1.692) > 兴安落叶松-白桦林(1.371),揭示出兴安落叶松种群在不同森林类型中地位和作用的差异。     

甘肃省民勤连古城自然保护区沙木蓼种群的结构与动态

根据甘肃省民勤连古城自然保护区沙木蓼种群的生境和植被差异,分别选择低山剥蚀残丘覆沙地(生境Ⅰ)和山前倾斜洪积扇沙地,有小型风积沙丘(生境Ⅱ)和无风积沙丘(生境Ⅲ)3种生境类型样地,对其种群的发育状况、年龄结构、静态生命曲线与分布格局进行了研究,揭示沙木蓼种群动态规律并评价其在构建荒漠植被方面的价值,为科学合理地管护和持续利用沙木蓼种质资源提供科学依据。研究结果表明,1)沙木蓼苗龄级、幼龄级、成熟龄级和老龄级种群密度大小顺序为生境Ⅲ生境Ⅰ生境Ⅱ,而3种生境中同龄级种群在株高、冠幅、新梢生长量方面差异不显著;2)苗龄级种群在3种生境下都占据了较大的优势地位,对沙木蓼种群的更新具有积极作用。生境Ⅰ和Ⅲ的幼龄级和成熟龄级的年龄结构为连续增长型,老龄级为独立的增长型,种群具有较大的发展空间。而生境Ⅱ的幼龄级和成熟龄级种群的年龄结构为连续的稳定型,老龄级种群为稳定型,种群结构比较稳定。3)种群lx,dx和qx曲线在苗龄级、幼龄级和成熟龄级阶段具有相同的变化趋势,其中苗龄级种群向幼龄级种群转变过程中均呈下降趋势,幼龄级和成熟级种群发育过程中基本保持平稳,但在老龄级种群阶段3种曲线变化趋势的差异性较大,其中生境Ⅰ和Ⅲ种群产生重叠,沙木蓼种群的死亡高峰主要发生在苗龄级和老龄级阶段,具有前期增长,中期稳定,后期衰退的一般规律。4)沙木蓼苗龄级、幼龄级和成熟级种群的分布格局均为聚集分布,而老龄级种群为随机分布。以上分析表明,3种生境下沙木蓼种群更新能力旺盛,种群结构趋于合理,生境差异(风沙流活动)只对土壤种子库、种子萌发和幼苗保存具有显著影响,对其它龄级种群发育没有显著影响,在荒漠植被演变中表现出较强的适应能力和优越性,因此沙木蓼在荒漠植被恢复和重建中具有重要的利用价值。     

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.     

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.     

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.     

Host plants of someRhinanthoideae (Scrophulariaceae) of eastern North America

Twenty three species in 11 genera were examined in the field to determine hosts. OnlyStriga asiatica andSeymeria cassioides have a narrow host range being restricted to grasses and pines, respectively. These are the only species which cause pronounced and sometimes serious host damage. The other species attach to a great diversity of hosts.     

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.     

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).