油菜素内酯对霍山石斛抗冷性能的调控效应

以2年生霍山石斛(Dendrobium huoshanense)的当年生茎叶为试验材料,在叶面喷施0、0.01、0.05、0.10和0.50mg·L-1油菜素内酯(BR)后,进行48h昼/夜温度为(4±1)℃/(2±1)℃的低温胁迫处理,测定其幼苗叶片叶绿素含量、抗氧化酶活性、丙二醛含量和电导率及脯氨酸含量和可溶性糖含量的变化,研究BR对霍山石斛抗冷性的影响。结果显示:(1)低温胁迫条件下,霍山石斛叶片叶绿素含量随胁迫时间推移而不断降低;SOD、POD与CAT活性变化趋势均呈单峰曲线,峰值出现在低温胁迫后10d;MDA含量和电导率均持续提高。(2)叶面喷施BR预处理显著缓解了低温胁迫对霍山石斛的伤害,显著提高其叶片叶绿素含量,显著增强了SOD、POD与CAT的活性,显著降低其MDA含量和电导率;并显著提高了叶片中脯氨酸含量与茎中可溶性糖含量。(3)BR浓度为0.10mg·L-1的处理效果显著优于其它浓度处理。研究表明,在低温胁迫条件下,油菜素内酯能够通过增强霍山石斛叶片内抗氧化酶活性,提高其渗透调节能力,有效减轻低温造成的过氧化伤害,提高叶片叶绿素含量,增强其植株的抗冷性,并以0.10mg·L-1油菜素内酯效果最佳。     

水杨酸对高温胁迫下铁皮石斛幼苗耐热性的影响

为研究不同浓度水杨酸对铁皮石斛幼苗耐热性的诱导效应,以移栽半年的铁皮石斛幼苗为实验材料,对不同浓度水杨酸诱导高温胁迫下铁皮石斛幼苗的耐热性进行外观评价及叶绿素、可溶性蛋白质、可溶性糖、丙二醛(MDA)、游离脯氨酸(Pro)含量以及超氧化物歧化酶(SOD)、过氧化酶(POD)、过氧化氢酶(CAT)、抗坏血酸过氧化物酶(APX)活性的动态测定,观察其动态变化趋势并筛选最佳施用浓度.结果显示:在高温胁迫环境下,随着胁迫时间的延长,不同浓度SA处理均能有效缓解高温对铁皮石斛植株伤害;1.5～2.0 mmol·L1SA处理使铁皮石斛叶片中SOD、POD活性显著提高,0.5～1.5 mmol·L-1 SA处理叶片中CAT、APX活性显著提高;1.5～2.0 mmol·L-1SA处理可显著促进叶片Pro、可溶性糖和可溶性蛋白的积累,有效抑制MDA含量的增加,且不同浓度处理之间差异显著.研究表明,适宜浓度水杨酸处理能提高铁皮石斛幼苗的耐热性,并以1.5 mmol·L-1浓度处理效果最好.     

ABA对低温胁迫下小桐子幼苗耐冷性及甜菜碱积累的影响

旨在探讨外源脱落酸(ABA)对低温胁迫下小桐子幼苗耐冷性及甜菜碱积累的影响。用150μmol/L ABA处理低温胁迫下的小桐子幼苗,研究其对小桐子幼苗存活率,根系活力,电解质渗漏率,MDA含量,甜菜碱含量及其代谢关键酶BADH活性和Jc BADH基因表达水平的影响。结果表明,外源150μmol/L ABA处理可显著提高低温胁迫下小桐子幼苗的存活率和根系活力,降低电解质渗漏率和MDA含量;ABA也提高了低温胁迫下小桐子幼苗的甜菜碱含量,上调了BADH的活性和Jc BADH的表达水平。因此,ABA可提高低温胁迫下小桐子幼苗的耐冷性,并且在ABA诱发的小桐子幼苗耐冷性的提高过程中,甜菜碱发挥着重要作用。     

6-BA和GA_3对盐胁迫下红杆铁皮石斛幼苗生理生化影响

以红杆铁皮石斛Dendrobium officinale为材料,研究植物生长调节剂6-苄氨基腺嘌呤(6-BA)和赤霉素(GA3)对其幼苗在Na Cl胁迫下的生理生化影响。结果表明,盐胁迫下,低浓度6-BA和GA3处理均可不同程度地提高红杆铁皮石斛幼苗的茎生长率,抑制根的伸长,且GA3抑制效果大于6-BA;随着6-BA浓度增加,盐胁迫下红杆铁皮石斛叶片叶绿素含量降低,类胡萝卜素含量则呈先升后降的趋势,而较高浓度GA3(4.0 mg·L-1)处理同时提高叶绿素和类胡萝卜素含量;低浓度6-BA(2.0 mg·L-1)处理能提高红杆铁皮石斛叶片可溶性糖含量,相同浓度GA3处理则降低可溶性糖含量,但高浓度GA3处理的可溶性糖含量与对照无显著差异。因此,添加适当浓度的植物生长调节剂能提高光合色素及可溶性糖的合成与积累,从而缓解盐胁迫对红杆铁皮石斛植株的伤害。     

4种化学调控剂对烟草幼苗耐冷性及其光合特性的效应研究

通过对烟草幼苗喷施不同浓度的CaCl2、赤霉素(GA3)、水杨酸(SA)和多效唑(PP333)进行预处理,比较分析4种化学调控剂处理对10℃低温胁迫下烟草幼苗耐冷性及其光合生理特性的影响。结果表明:(1)与喷施蒸馏水对照相比,4种化学调控剂预处理均可提高烟草幼苗的干物质积累量、根系活力、脯氨酸含量及光合效率,降低丙二醛(MDA)含量,总体上提高了烟草幼苗素质。(2)在10℃低温胁迫下,4种化学调控剂预处理可使烟草幼苗保持比对照更高的单株干重、相对生长速率、干物质积累速率、根系活力、脯氨酸含量、叶绿素含量、净光合速率、胞间CO2浓度、气孔导度和蒸腾速率,并减缓了低温诱导的MDA积累和相应的膜脂过氧化作用,最终提高烟草幼苗的耐冷性。(3)4种化学调控剂处理提高烟草幼苗耐冷性的程度不同,在该研究中以SA综合效果最好。     

兰科菌根真菌对干旱胁迫下铁皮石斛生长和抗氧化能力及相关基因表达的影响

利用盆栽的方式研究了干旱胁迫下接种兰科菌根真菌(OM)对铁皮石斛生长的影响,并分析了铁皮石斛叶片相对含水量、游离脯氨酸含量、电解质渗透率、丙二醛(MDA)含量、活性氧成分、抗氧化酶活性变化,用定量PCR技术分析了相关抗氧化酶基因的表达特性,以探讨菌根真菌对铁皮石斛干旱胁迫的缓解作用及其机制。结果表明：(1)与正常水分条件相比,干旱胁迫显著降低了铁皮石斛幼苗的生物量和叶片相对含水量,提高了叶片电解质渗透率、脯氨酸含量、MDA含量、O-·2产生速率和H2O2水平。(2)菌根真菌能显著提高干旱胁迫下铁皮石斛叶片相对含水量,降低叶片电解质渗透率、脯氨酸含量、MDA含量、O-·2产生速率和H2O2水平;在不同水分条件下,菌根真菌均能有效促进铁皮石斛幼苗生长,其株高、根重、茎叶重和总生物量均大于未接种组。(3)菌根真菌可诱导干旱胁迫下铁皮石斛超氧化物歧化酶(SOD)、过氧化物酶(POD)和过氧化氢酶(CAT)基因的表达,提高SOD、POD和CAT的活性,有效缓解干旱胁迫对质膜的过氧化伤害。研究认为,菌根真菌能提高干旱胁迫下铁皮石斛的抗氧化酶活性及其相关基因表达水平,增强铁皮石斛抗氧化防御能力,有效缓解干旱胁迫对铁皮石斛幼苗生长的抑制。     

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.     

外源褪黑素对低温胁迫下茄子幼苗生长及其光合作用和抗氧化系统的影响

以‘沪茄08-1’茄子幼苗为试验材料,采用基质栽培方式,研究了叶面喷施50~200μmol·L-1外源褪黑素(melatonin,MT)对低温胁迫[(10±1)℃(昼)/(5±1)℃(夜)]下茄子幼苗生长、光合作用和抗氧化系统等生理指标的影响,以明确外源MT在茄子幼苗抵御低温逆境方面的生理机制。结果显示:(1)低温胁迫处理后,茄子幼苗株高、茎粗、地上部鲜重和根系鲜重、叶绿素含量、叶片净光合速率(Pn)、气孔导度(Gs)和蒸腾速率(Tr)均显著降低,丙二醛(MDA)含量、超氧阴离子产生速率(O-·2)和过氧化氢(H2O2)含量均显著增加。(2)幼苗叶片超氧化物歧化酶(SOD)、过氧化物酶(POD)、过氧化氢酶(CAT)、抗坏血酸过氧化物酶(APX)、谷胱甘肽还原酶(GR)、脱氢抗坏血酸还原酶(DHAR)活性及抗坏血酸(AsA)和谷胱甘肽(GSH)含量均显著升高,而其脯氨酸(Pro)和可溶性蛋白质含量均显著增加;外源MT处理可有效增强低温胁迫条件下茄子幼苗叶片中SOD、POD、CAT、APX、GR、DHAR活性,提高AsA和GSH含量,增加Pro和可溶性蛋白含量,显著抑制其叶片MDA、O-·2及H2O2的积累。研究表明,外源MT主要通过增强低温胁迫下茄子幼苗的光合作用以及清除活性氧的能力,减缓低温胁迫的危害,提高茄子幼苗对低温胁迫的耐性。     

复合外源物质对玉米幼苗抗寒性的影响

该研究采用不同浓度的水杨酸(SA)、脱落酸(ABA)、磷酸二氢钾(KH2PO4)以及抗坏血酸(VC)进行正交组合获得不同浓度组合的复合外源物质,同时以蒸馏水处理作为对照,将其喷施于玉米幼苗后进行低温胁迫处理,在胁迫结束后使幼苗恢复生长,并测定叶片相关生长指标及生理生化指标的变化。结果表明:(1)与对照组相比,9种复合外源物质处理均可显著提高玉米幼苗的相对生长速率、干物质积累速率及脯氨酸含量,降低相对电导率,总体上提高了玉米幼苗的素质。(2)在4℃低温胁迫下,9种复合外源物质处理下幼苗相对生长速率、干物质积累速率、根系活力、脯氨酸含量、可溶性蛋白含量及可溶性糖含量,均显著高于对照,并减缓了丙二醛的积累和相应的膜脂过氧化,降低了相对电导率,提高了玉米幼苗的耐冷性。低温胁迫条件下,水杨酸、脱落酸、磷酸二氢钾和抗坏血酸四种物质组成的复合物可以提高玉米幼苗的耐冷性,其中以SA0.14 g·L~(-1)+ABA 0.015 g·L~(-1)+KH_2PO_4 3.0 g·L~(-1)+V_C 3.0 g·L~(-1)的复合物效果最好。该研究结果为新型复合抗寒剂的应用推广提供了技术支持。     

干旱胁迫下叶面喷施褪黑素对滁菊幼苗生理生化特性的影响

以滁菊品种"金玉"幼苗为材料,通过日光温室内盆栽实验,在中度干旱胁迫条件下(土壤田间持水量的40%),研究叶面喷施外源褪黑素(MT,100μmol·L-1)对滁菊幼苗生长及生理生化特性的影响,探讨提高滁菊耐干旱性的新途径。结果表明:(1)与对照相比,干旱胁迫处理降低了滁菊叶片叶绿素含量、净光合速率和水分利用效率,提高了可溶性蛋白质、可溶性糖和脯氨酸含量,而叶片MDA含量和相对电导率显著增加,显著抑制了滁菊幼苗的生长。(2)在干旱胁迫条件下,外源MT可显著提高滁菊幼苗叶片脯氨酸、可溶性蛋白质和可溶性糖的含量,并显著降低了叶片相对电导率和MDA含量,使幼苗保持较高叶绿素含量和净光合速率。(3)与干旱胁迫处理相比,外源MT处理的滁菊地上部和根系干重、鲜重均显著增加。研究发现,外源褪黑素(MT)在一定程度上可通过促进滁菊幼苗渗透调节物质的积累,有效降低干旱胁迫对其细胞膜的伤害,维持其正常的细胞膜功能,保持其较高的光合速率和水分利用效率,从而增加其对干旱环境的适应性。     

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.     

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.     

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.     

A molecular phylogeny of Hebeloma species from Europe

In order to widen the scope of existing phylogenies of the ectomycorrhizal agaric genus Hebeloma a total of 53 new rDNA ITS sequences from that genus was generated, augmented by sequences retrieved from GenBank, and analysed using Bayesian, strict consensus and neighbour joining methods. The lignicolous Hebelomina neerlandica, Gymnopilus penetrans, and two species of Galerina served as outgroup taxa. Anamika indica, as well as representatives of the genera Hymenogaster and Naucoria, were included to test the monophyly of Hebeloma, which is confirmed by the results. Hebeloma, Naucoria, Hymenogaster and Anamika indica cluster in a strongly supported monophyletic hebelomatoid clade. All trees largely reflect the current infrageneric classification within Hebeloma, and divide the genus into mostly well-supported monophyletic groups surrounding H. crustuliniforme, H. velutipes, H. sacchariolens, H. sinapizans, and H. radicosum, with H. sarcophyllum being shown at an independent position; however this is not well supported. The section Indusiata divides with strong support into three groups, the position of the pleurocystidiate Hebeloma cistophilum suggests the possible existence of a third subsection within sect. Indusiata. Subsection Sacchariolentia is raised to the rank of section.     

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.     

Interaction of Synthetic Analogues of Natural Chalcones and Flavones with Guanidine

The reaction of chalcones and flavones with guanidine in ethanol results in 2-(2-aminopyrimidinyl-4)-phenols.     

Demographic characteristics of an intertidal bay goby (Lepidogobius lepidus)

Synopsis In a fourteen month study (May 1976 – June 1977) I examined the following characteristics of an intertidal bay goby (Lepidogobius lepidus) in Morro Bay, California, U.S.A.: annual and seasonal patterns of abundance, age composition and growth rates, survivorship and mortality patterns, and the reproductive cycle for female gobies. Fishes were collected with the aid of quinaldine and otoliths and ovaries removed. Age and growth rates were estimated from otolith annuli using a back calculation formula and a Brody-Bertalanffy growth curve. Mortality rates were derived using the methods of Heincke (1913), Robson & Chapman (1960), mean age, and a catch curve (Ricker 1975). A gonad index was used to describe the annual reproductive cycle. Results indicated that abundance fluctuated seasonally and that these fluctuations appeared to be caused by reproductive emigrations. Bay gobies reached an age of 7+ and a standard length of 87 mm. Growth was relatively constant (6 mm yr⁻¹) until age 5, at which point it began to decline. The mean rates of survivorship, mortality, and instantaneous mortality were 0.75, 0.25, and 0.29 respectively. Mortality rates for individual age classes ranged from 0.13 to 0.51 and increased with age. This stock appears to reproduce mainly during the winter.