不同种源栓皮栎光响应曲线的模型拟合及参数比较

利用2年生栓皮栎实生苗,通过直角双曲线模型(RHM)、非直角双曲线模型(NHM)、指数函数(EM)、直角双曲线修正模型(MRHM)和分段函数(SFM)对辽宁庄河(LNZH)、北京平谷(BJPG)、陕西黄龙(SXHL)、河南济源(HNJY)、湖北鹤峰(HBHF)、云南安宁(YNAN)6个种源地栓皮栎的光合光响应曲线进行拟合,对5种模型拟合结果进行比较,分析了6个种源栓皮栎的光合特性,以期提高光合光响应曲线拟合的准确性并对不同种源植物在生境变化情形下的光合生理特征进行探索。研究发现:(1)5个模型中MRHM和SFM优势明显,其拟合结果与观测值更吻合;(2)不同模型拟合对α、Pnmax及Rd结果影响较大,部分拟合参数在模型间差异显著,如EM和SFM拟合的α和Rd显著低于其他模型(P0.05),RHM和NHM拟合的Pnmax显著高于其他模型(P0.05),而且模型选择影响种源试验部分光响应参数结果差异的显著性水平;(3)栓皮栎种源间Pnmax和Rd差异显著(P0.05),其中SXHL种源Pnmax和HNJY种源Rd显著高于其他种源(P0.05);(4)通过光响应曲线比较,除LNZH种源外其余暖温带种源2年生幼苗均能很好地适应试验地生境条件。     

闽楠幼树光合特性及生物量分配对光环境的响应

设置100%光环境(L100)、40%光环境(L40)、8%光环境(L8)3种光照梯度,分析万木林闽楠(Phoebe bournei)幼树的光合特性及生物量分配特征对不同光环境的响应。结果表明:(1)闽楠幼树在不同光环境下的最大净光合速率(Pnmax),表观量子效率(AQY),光饱和点(LSP),光补偿点(LCP),暗呼吸速率(Rd)均有显著差异(P<0.05),且随着光照强度的降低,Pnmax,LSP,LCP,Rd随之降低,而AQY却呈现升高的趋势。(2)总生物量、茎生物量、叶生物量、根生物量均表现为L100最大,根冠比、叶生物量比、茎生物量比及根生物量比在3种光环境下无显著差异。(3)闽楠幼树通过改变光合特性,生物量积累来适应光环境的变化,其中光照强度的降低限制了生物量的积累,但并未显著改变生物量地上地下分配比例。闽楠幼树在3种光环境下生物量分配比例并无显著的改变,生物量分配可塑性极低可能是闽楠零散分布的一个重要非人为干扰因素。(4)闽楠幼树所采取的生存策略以地上部分生长为主,光照强度降低时则采取保守策略进行缓慢的资源获取和消耗,全光照条件下采取快速的资源获取和消耗策略。未来造林时可以将闽楠与毛竹(Phyllostachys pubescens)混交来减少郁闭度,促进闽楠幼树的生长。     

广西4个种源蚬木苗木光合特性的比较

以广西4个不同种源蚬木Excentrodendron hsienmu苗为研究材料, 测定及分析其光响应曲线及光合参数日变化规律, 以期为蚬木引种和优选提供理论依据。结果表明: 武鸣种源具最高的光饱和点(LSP)和光补偿点(LCP), 具有较好的适应强光的能力。靖西种源具有较高的最大光合速率(Pmax)、LSP和斜率(AQY), 以及较低的LCP和暗呼吸速率(Rd), 因此可能具有较强的同化能力。大新种源虽LSP最低, 但其具有最高的Pmax和最低的Rd, 以及较低的LCP, 这可能也赋予了该种源具有较强的同化能力。4个种源蚬木均有明显的光合午休现象, 并且净光合速率(Pn)、蒸腾速率(Tr)、气孔导度(Gs)、水分利用效率(WUE)在不同种源间均存在显著差异, 其中武鸣种源具有较低的Tr和较高的WUE, 靖西种源表现了较高的Gs和Tr。因此, 在相对保水性较好的赤红壤土地上种植蚬木, 可优先选择靖西和大新种源。     

光强与水分处理下景宁木兰光合光响应模型拟合比较

采用5种数学模型(直角双曲线模型、非直角双曲线模型、二次函数模型、指数模型、直角双曲线修正模型)对不同光照与水分处理下景宁木兰(Magnolia sinostellata)幼苗光响应过程进行拟合分析,以期筛选出光照与水分胁迫下景宁木兰适宜的光响应模型。结果表明:(1)5种拟合模型对景宁木兰光响应过程拟合精度为:指数模型直角双曲线修正模型直角双曲线模型非直角双曲线模型二次函数模型。(2)光合参数的拟合效果表现为:指数模型对景宁木兰最大净光合速率(Pnmax)、光饱和点(LSP)进行求解较准确,直角双曲线修正模型对光补偿点(LCP)求解最佳,而暗呼吸速率(Rd)的结果采用非直角双曲线模型较为合理。(3)景宁木兰幼苗能适应一定的弱光及流动水环境,而深度遮阴及积水环境抑制景宁木兰幼苗的光合速率。     

四种水稻品种的光合光响应曲线及其模型拟合

应用4种典型的光响应模型对4个水稻品种“02428”、“淦鑫688”、“JR8892-1”和“JR8892-2”叶片的光合光响应曲线进行了拟合.结果表明:直角双曲线模型、非直角双曲线模型、指数函数以及修正的直角双曲线模型对4个水稻品种的光合光响应曲线都可以进行拟合,决定系数均为R2 ＞0.99.但只有修正的直角双曲线模型可以拟合发生光抑制部分的光响应曲线,且可直接计算其饱和光强(Isat);由各模型计算的光合参数可知,直角双曲线模型、非直角双曲线模型求得的最大净光合速率(Pnmax)远高于实测值,指数函数与修正的直角双曲线模型求得的Pnm.与实测值最为接近;直角双曲线、非直角双曲线模型以及指数函数求得的Isat均与实测值相差较大,除了“JR8892-1”采用指数函数求得的Isat大于实测值外,其余3个品种用上述3种模型拟合求得的Isat均小于实测值,唯有修正的直角双曲线模型求得的Isat与实测值最为相符;对于低光强部分的参数光补偿点(Ic)与暗呼吸速率(Rd),修正的直角双曲线模型最接近其测量值;不同水稻品种的光合特性,“JR8892-1”饱和光强与最大净光合速率明显高于高光效品种“02428”;处于分蘖盛期的“JR8892-2”也表现出较高的饱和光强和最大净光合速率,而超级稻“淦鑫688”相对于其他品种,则具有较低的暗呼吸速率,光合产物消耗少.     

不同地理种源长白落叶松生理生态特性的研究

在人工气候室中测定了１０个种源长白落叶松二年生硬枝扦插苗的光合、水分生理生态参数。结果表明,不同种源的长白落叶松生理生态参数变异较大,但有一定规律可循。各种源的总光合速率＞最大净光合速率＞净光合速率＞半饱和光强时的净光合速率＞光呼吸速率＞呼吸速率,只偶有例外。各参数中呼吸速率在各种源间变异最小,光呼吸速率变异较大,总光合速率变异最大。各参数在种源间的变化趋势均与净光合速率一致,即净光合速率大的种源其它参数也大,净光合速率小的种源其它参数也小。相对光呼吸在各种源间变异较大,其释放的ＣＯ２相当于光合固定ＣＯ２的总量的１／３。光补偿点、饱和点和半饱和点在各种源间的变异较大。水分利用率在各种源间的较大变异主要是由净光合速率引起,与蒸腾速率关系不大。净光合速率占总光合速率的百分比、呼吸功效、ＣＯ２补偿点、蒸腾速率和水势在各种源间变异不大     

生长光强对六个橡胶树品种幼苗光合特性的影响

研究了6个橡胶树品种幼苗(适应1年后)在不同生长光强(100%、50%、25%和5%自然光)下的叶片光合系统对光强和CO2浓度的响应特性。结果表明,6个橡胶树品种对不同的光环境均表现出较强的适应性。在不同生长光强下,橡胶树幼苗叶片的最大光合速率(Pmax)、光补偿点(LCP)、暗呼吸速率(Rd)、磷酸丙糖利用速率(TPU)、最大羧化速率(Vcmax)和最大电子传递速率(Jmax)以及叶绿素含量(Chl)均有显著差异(P<0.05),而光饱和点(LSP)和AQY(表观量子效率)则无显著差异。相同生长光强下,6个橡胶树品种间叶片的最大光合速率(Pmax)、暗呼吸速率(Rd)、磷酸丙糖利用速率(TPU)、最大电子传递速率(Jmax)和叶绿素含量(Chl)有显著差异(P<0.05),其光补偿点(LCP)、最大羧化速率(Vcmax)和表观量子效率(AQY)则无显著差异。综合比较各参数,RRIM600、云研77-4和PR107适宜于相对光强为100%~50%的植胶环境,而云研77-2、GT1和热研523适宜于相对光强为50%~25%的植胶环境。     

伏牛山自然保护区森林生态系统植物功能群光合特性

植物功能群(PFG)把一系列植物归为一个功能团体,可以作为植被随环境动态变化的基本单元,简化相关研究。植物功能群内不同物种的生理特性差异是功能群存在的基础,也影响着功能群整体的功能。采用种间联结法并结合优势种在海拔梯度上的变化,将伏牛山自然保护区森林生态系统各层优势种划分为4组植物功能群,研究每组植物功能群内不同物种的光合特性。对光合-光响应、最大净光合速率(Pn)、暗呼吸速率(Rd)、光补偿点(LCP)、光饱合点(LSP)和表观量子效率(AQY)等指标进行分析和比较,结果表明:植物功能群内不同物种的光补偿点和暗呼吸速率的变异系数最高分别达70.47%和74.29%,功能性状存在着显著的互补性,这是物种能长期共存的主要原因。乔木的最大净光合速率在7—8μmol CO_2m~(-2)s~(-1)之间,对高光强的适应能力较高。同一功能群内各层植物光饱合点在1200—1500μmol m~(-2)s~(-1)之间,差别不大。林下灌木、草本植物对弱光的利用效率较乔木高。同一功能群内物种功能性状的差异及不同植物功能群间整体性状的差异,影响着森林生态系统的结构、功能、过程和生态系统服务。     

两个品种转基因抗虫棉光合生理的CO_2响应

栽培环境条件的改变会对转基因作物产生深远影响。以2种不同转基因棉花及其亲本对照为材料,研究了盆栽种植条件下不同棉花品种在蕾期和吐絮期光合生理特性CO2响应特征。结果表明,与各自的常规棉对照比较,两种转基因抗虫棉单叶净光合速率CO2响应的特征参数表观初始羧化效率(CE)、表观暗呼吸速率(Rd)和最大净光合速率(Pmax,c)虽有一定程度的变化,但其差异均未达到显著水平。在高CO2浓度范围内(700μmol.mol-1),转基因抗虫棉单叶净光合速率和水分利用率(WUE)的CO2响应曲线特征发生变化,且与品种及生育时期有关。两种转基因抗虫棉在不同生育时期的气孔导度(Gs)对CO2浓度的响应特征与其常规棉对照相似,短期CO2浓度增高对转基因抗虫棉的气孔导度没有显著性影响。     

C_4植物玉米的光合-光响应曲线模拟研究

光是植物光合作用最基本的一个决定因子,准确分析光响应曲线及其参数是研究光合生理生态过程对环境变化响应的重要途径;但相关模型及其模拟的准确性仍待改进。该研究基于C_4作物玉米(Zea mays)不同干旱处理试验资料,比较研究了现有光响应模型(直角双曲线模型、非直角双曲线模型、直角双曲线修正模型、指数模型、二次函数模型以及新提出的改进模型)的适应性。结果表明,改进的光响应模型具有较好的精确度,可较准确地描述光响应曲线,也能够准确拟合最大净光合速率、光饱和点、光补偿点以及暗呼吸速率4个关键光合参数。该结果为研究植物光合生理生态过程及其环境适应性提供了一个改进的模拟方法。     

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.     

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。     

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).     

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.     

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.     

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.