Proton-motive force and the motile behavior of Bacillus subtilis

Changes in the proton-motive force cause a transient change in the motile behavior of Bacillus subtilis cells. Both an increase and a decrease in the proton-motive force cause transient tumbling. Simultaneous decrease of proton-motive force and increase of attractant concentration lessens the response toward the attractant. A simultaneous increase of proton-motive force and increase of attractant concentration prolonges the response toward attractant. A hypothesis explaining the various effects is given.Abbreviations KT medium potassium taxis medium - NaT medium sodium taxis medium - HT medium acidic taxis medium - OHT medium alkaline taxis medium - DNP 2,4-dinitrophenol     

Occurrence of nitrogen fixation among Vibrio spp.

Virtually all Vibrio spp. known and available in culture collections and several newly isolated Vibrio sp. were tested for their ability to fix molecular nitrogen, using the acetylene reduction technique, the fixation of the heavy isotope ¹⁵N, and by growth on media devoid of combined nitrogen. Among the 27 species tested, four, including V. diazotrophicus, proved to be nitrogenase-positive. The potential of nitrogen fixation was now also discovered in V. natriegens, V. pelagius and V. cincinnatiensis. Among the 9 newly isolated strains, 4 were nitrogenase-positive. These strains were classified as V. diazotrophicus on the basis of DNA homology studies. Nitrogenase was only induced during growth under anaerobic conditions. Dissolved oxygen as low as 1 M inhibited nitrogenase completely. This inhibition at low oxygen concentration, however, was reversible. 50–100 M dissolved oxygen inhibited nitrogenase irreversibly.This work was carried out at Geomicrobiology Division, the University of Oldenburg, FRG     

Hypoxia tolerance and air-breathing ability correlate with habitat preference in coral-dwelling fishes

Hypoxia tolerance and air-breathing occur in a range of freshwater, estuarine and intertidal fishes. Here it is shown for the first time that coral reef fishes from the genera Gobiodon, Paragobiodon and Caracanthus, which all have an obligate association with living coral, also exhibit hypoxia tolerance and a well-developed air-breathing capacity. All nine species maintained adequate respiration in water at oxygen concentrations down to 15–25% air saturation. This hypoxia tolerance is probably needed when the oxygen levels in the coral habitat drops sharply at night. Air-breathing abilities of the species correlated with habitat association, being greatest (equaling oxygen uptake in water) in species that occupy corals extending into shallow water, where they may become air exposed during extreme low tides. Air-breathing was less well-developed or absent in species inhabiting corals from deeper waters. Loss of scales and a network of subcutaneous capillaries appear to be key adaptations allowing cutaneous respiration in air. While hypoxia tolerance may be an ancestral trait in these fishes, air-breathing is likely to be a more recent adaptation exemplifying convergent evolution in the unrelated genera Gobiodon and Caracanthus in response to coral-dwelling lifestyles.     

Comparison of whole wood and cellulose carbon and oxygen isotope series from Pinus nigra ssp. laricio (Corsica/France)

Stable isotopes in tree rings have widely been used for palaeoclimate reconstructions since tree rings record climatic information at annual resolution. However, various wood components or different parts of an annual tree-ring may differ in their isotopic compositions. Thus, sample preparation and subsequent laboratory analysis are crucial for the isotopic signal retained in the final tree-ring isotope series used for climate reconstruction and must therefore be considered for the interpretation of isotope–climate relationships. This study focuses on wood of Corsican Pine trees (Pinus nigra ssp. laricio) as this tree species allows to reconstruct the long-term climate evolution in the western Mediterranean. In a pilot study, we concentrated on methodological issues of sample preparation techniques in order to evaluate isotope records measured on pooled whole tree-ring cellulose and whole tree-ring bulk wood samples. We analysed 80-year long carbon and oxygen chronologies of Corsican Pine trees growing near the upper tree line on Corsica. Carbon and oxygen isotope records of whole tree-ring bulk wood and whole tree-ring cellulose from a pooled sample of 5 trees were correlated with the climate parameters monthly precipitation, temperature and the self-calibrating Palmer Drought Severity Index (sc-PDSI). Results show that the offsets in carbon and oxygen isotopes of bulk wood and cellulose are not constant over time. Both isotopes correlate with climate parameters from late winter and summer. The carbon and oxygen isotope ratios of cellulose are more sensitive to climatic variables than those of bulk wood. The results of this study imply that extraction of cellulose is a pre-requisite for the reconstruction of high-resolution climate records from stable isotope series of P. nigra ssp. laricio.     

Seasonal and environmental effects on the blood hemoglobin concentrations of some Panamanian air-breathing fishes

Synopsis Interspecific differences in blood hemoglobin concentration ([Hb]) occur among air breathing fishes. However, the effect on [Hb] of factors such as air-breathing organ structure and blood circulation pattern, air breathing behavior, as well as season and environmental conditions have not been fully examined. [Hb] in seven Panamanian species of air-breathing freshwater teleost fishes were compared and were monitored for most species during the wet and dry seasons and in hypoxic laboratory conditions. Fishes studied were Ancistrus, Hypostomus, and Loricaria (Family Loricariidae); Hoplosternum (Callichthyidae); Synbranchus (Synbranchidae); Piabucina (Lebiasinidae); and Dormitator (Eleotridae). [Hb] in these species ranged from 4.8 to 14.6 g 100 ml^–1 (g%). Ancistrus, Hypostomus, and Dormitator significantly increased [Hb] during the dry season and, with Piabucina, also increased [Hb] when acclimated to hypoxia in the laboratory. An increase in [Hb] during the dry season may precondition facultative air breathers for habitat hypoxia (and the need to respire aerially) in the event this occurs. Intraspecific differences in both [Hb] and in red cell Hb-phosphate ratio, an index of oxygen affinity, were found in populations of Hypostomus and relate directly to differences in habitat oxygen level. In all species tested alterations in blood hematocrit (Hmct) and mean corpuscular hemoglobin concentration (MCHC) occurred only with correspondingly large net changes in blood [Hb]. The [Hb] of Loricaria, Synbranchus, and Hoplosternum was not affected by season or hypoxia and this may be due to behavioral and physiological adaptations that reduce the transbranchial loss of aerially-obtained oxygen or to a ventilatory mode that precludes this possibility.     

中国假尾孢属的研究V

本文报导中国假尾孢属的30个种,其中有2个新种:透骨草假尾孢(Pseudocercospora phrymae),槐假尾孢(P. sophorae), 6个新组合:无花果假尾孢(P. fici),爵床假尾孢(P. justiciae),木犀生假尾孢(P. osmanthicola),海桐花假尾孢(P. pittospori),色柱假尾孢(P. polygonorum),花椒假尾孢(P. xanthoxyli)和5个中国新记录。文中对新种和新组合进行了描述并绘图,其他种作了简要描述或讨论。研究的标本保存在中国科学院微生物研究所真菌标本室(HMAS)。     

中国假尾孢属的研究VI.

本文报道中国假尾孢属的16个种,其中有3个新种:藤山柳假尾孢(Pseudocercospora clematoclethrae),仙茅假尾孢(P. curculiginis,),豆付柴假尾孢(P. premnicola), 8个新组合:金粟兰假尾孢(P. chloranthe), 榅桲假尾孢(P. cydoniae),福岗假尾孢(P. fukuokaensis),土连翘假尾孢(P. hymenodictyonis),南五味子假尾孢(P. kadsurae), 野岛假尾孢(P. nojimae).绣线菊假尾孢(P. spiraeicola),球形假尾孢(P. sphaeriiformis)和3个中国新纪录。文中对新种进行了描述并绘图。研究的标本保存在中国科学院微生物研究所真菌标本室(HMAS)。     

New taxa ofRubiaceae-Rubieae from Iran

Asperula sect.Oppositifoliae is validated. 2 new species ofAsperula and 7 new species and 1 variety ofGalium from Iran are described, discussed in respect to their affinities and illustrated. 2 subspecies are raised to species rank.     

Sensorimotor transformation from light reception to phototactic behavior inDrosophila larvae (Diptera: Drosophilidae)

In this paper we examine theDrosophila melanogaster larval response to light. We survey the morphology of the larval visual and motor systems in relation to larval locomotory behavior and phototaxis. In addition, this paper proposes a model of sensorimotor transformation and examines the reversal in taxis occurring at theD. melanogaster larval wnadering stage.     

水体溶氧影响陆生植物喜旱莲子草(Alternanthera philoxeroides)和牛鞭草(Hemarthria altissima)对完全水淹的耐受力

溶氧是水环境中一个重要的环境因子,为了探讨水中的溶氧含量水平是否会对陆生植物的耐淹能力造成影响,研究了陆生植物喜旱莲子草(Alternanthera philoxeroides)和牛鞭草(Hemarthria altissima)在遭受不同溶氧含量水体完全淹没后的生长表现、存活情况和非结构碳水化合物的变化。实验结果表明:(1)水体中的溶氧含量显著影响了处于完全水淹环境中的喜旱莲子草和牛鞭草的存活。受高溶氧水体完全水淹的喜旱莲子草和牛鞭草主茎的完好程度和存活叶的数量均显著高于遭受低溶氧水体完全水淹的喜旱莲子草和牛鞭草,喜旱莲子草和牛鞭草在高溶氧水体完全水淹后的生物量比低溶氧水体完全水淹后要高;(2)水体中的溶氧含量显著影响了处于完全水淹环境中的喜旱莲子草和牛鞭草的生长,受高溶氧水体完全水淹的喜旱莲子草主茎伸长生长和不定根生长显著强于受低溶氧水体完全水淹的喜旱莲子草,在不定根的生长上牛鞭草也具有同样的表现。(3)高溶氧水环境有利于减小被完全淹没的喜旱莲子草和牛鞭草的碳水化合物消耗,两种植物在受高溶氧完全水淹后体内具有的非结构性碳水化合物含量均比受低溶氧完全水淹后高。(4)喜旱莲子草比牛鞭草能更好地耐受完全水淹,当处于低溶氧完全水淹时表现得更为明显,本研究表明入侵物种喜旱莲子草比本地物种牛鞭草具有更强的环境适应能力和水淹耐受能力。     

Immersion survival differs among three Diabrotica species

Soil dwelling invertebrates including insects and their larvae are subjected to severe oxygen limitations when the soil becomes saturated or covered by water. Differential survival of this stress may in part explain ecological range of a species and could lead to cultural control methods for economically important species. We tested immersion survival for larvae of three species of Diabrotica (viz., D. balteata LeConte, D. undecimpunctata undecimpunctata Mannerheim, and D. virgifera virgifera LeConte). Groups of larvae were submersed in conditioned, hypoxic (dissolved oxygen <0.3 ppm) tap water, held at 10, 15, 20, or 25 °C, and periodically removed and assayed for survivorship. We found that time to 50% mortality (LT₅₀) differed significantly between species. Third instar D. u. undecimpunctata were most sensitive to immersion at 25 °C (LT₅₀=9 h), D. balteata were intermediate (LT₅₀=15 h) and D. v. virgifera larvae were least sensitive (LT₅₀=23 h). Second instar D. v. virgifera were significantly more tolerant of immersion than the other species (LT₅₀=56 h versus 15 h for D. u. undecimpunctata and 11 h for D. balteata). Mortality during immersion corresponds with the build up of lactic acid. Survivorship for all species increased with decreasing temperature. The use of flooding in rootworm management is briefly discussed.     

Role of respiration and glutathione in cadmium-induced oxidative stress in Escherichia coli K-12

Cadmium is a widespread pollutant that has been associated with oxidative stress, but the mechanism behind this effect in prokaryotes is still unclear. In this work, we exposed two glutathione deficient mutants (ΔgshA and ΔgshB) and one respiration deficient mutant (ΔubiE) to a sublethal concentration of cadmium. The glutathione mutants show a similar increase in reactive oxygen species as the wild type. Experiments performed using the ΔubiE strain showed that this mutant is more resistant to cadmium ions and that Cd-induced reactive oxygen species levels were not altered. In the light of these facts, we conclude that the interference of cadmium with the respiratory chain is the cause of the oxidative stress induced by this metal and that, contrary to previously proposed models, the reactive oxygen species increase is not due to glutathione depletion, although this peptide is crucial for cadmium detoxification.     

Zwergstrauchige Arten der FlechtengattungCaloplaca

The frutescent species of the lichen genusCaloplaca are usually united in sect.Thamnoma, but they do not form a natural group. They are derived from different species groups within sect.Gasparrinia from different parts of the world, presumable from species having scleroplectenchymes in cortex and medulla. The algal cells are concentrated between the scleroplectenchymatic strands in large and dense groups, from where medullary plectenchyme extends to the cortex and forms characteristic pseudocyphellae there.—Most of the species seem to be ornithocoprophilous; they grow on rocks along marine coasts where much fog is induced by cold currents.—Caloplaca cribrosa is endemic in Tasmania and New Zealand,C. regalis and the doubtfulC. ambitiosa belong to the antarctic element.C. fragillima from central Chile seems to be propagated by thallus fragments.C. coralloides andC. thamnodes are endemic to California and Baja California respectively.C. cladodes from the Rocky Mountains deviates in many characteristics from the other species i.a. by it different ontogenetic development, reduced spore septum, and cementing amyloid polysaccharides within the scleroplectenchymatic strands. The African species are characterized by their distinctly dorsiventral lobes and usually possess oil cells in some of the paraphyses.Caloplaca bonae-spei, C. fragillima andC. thamnodes are new to science.

     

A genetic contribution to the taxonomy ofOenothera sect.Oenothera (including subsectionsEuoenothera,Emersonia, Raimannia andMunzia)

Based on an analysis of results from experimental hybridization, the plants assigned byMunz toOenothera subg.Oenothera and subg.Raimannia, now divided into approximately 76 species, are referred to a single section,Oenothera. This section is in turn divided into five subsections:Euoenothera, Munzia, Raimannia, Emersonia, and an undescribed group of three species related toOenothera pubescens. Euoenothera is maintained in the traditional sense, and includes about 14 species of North America, widely naturalized elsewhere.Munzia consists of 45 species, comprising three series, and native to South America.Raimannia is restricted to a group of approximately 11 North American species.Emersonia comprises four rather heterogenous species of northern Mexico and southern New Mexico, of whichOenothera macrosceles, O. maysillesii, andO. organensis have been described. Within these four subsections, interspecific hybrids can be made in general, although plastid differentiation often leads to incompatibilities. With varying degrees of difficulty, hybrids were produced in all intersectional combinations involvingEuoenothera, Emersonia, Munzia, andRaimannia, the most difficult being those betweenEmersonia andRaimannia. Based on their habit and distribution,Emersonia species, and especiallyOenothera maysillesii, appear to resemble most closely the common ancestor of the section,Euoenothera andMunzia to have been derived from it or its common ancestor, andRaimannia perhaps to be more closely related to the phylogenetic branch that leads toEuoenothera.     

河北小五台山叶生丝孢菌

小五台山自然保护区位于河北省西部,为河北省第一高峰。变化悬殊的地形,使其由低谷到亚高山草甸呈明显独特的垂直植被类型分布带,山势陡峻,谷路隘险,具有华北地区罕见的森林植被及丰富的植物资源。狭谷陡峰,葳蒐险奇的地形地貌,又形成了多变的气候特征,因此蕴藏着相当丰富的真菌资源。作者1990年8月在该地区考察期间,共采集涉及林木、农作物、花卉、蔬菜等植物病害标本240份。本文报道小五台山的丝孢菌(Hyphomycetes)14属40种,其中有二个新种:(木来)木菌绒孢(Mycovellosiella coni Y.L.Guo, sp. nov.),五味子色链隔孢(Phaeoramularia schisandrae Y.L. Guo, sp. nov.)和7个中国新记录种:沼泽尾孢(Cercospora paludicola Speg.),白面子菌绒孢[Mycovellosiella ariae(Fuckel) U. Braun],薯蓣菌绒孢[Mycovellosiella dioscorae(Vassiljevski) Pons & Sutton],当归柱隔孢(Ramularia angelicae v. Hohnel),白芷柱隔孢[Ramularia heraclei(Oud.)Sacc.),莴苣柱隔孢(Ramularia lactucosa Lamb. & Fautr.)和虎耳草柱隔孢(Ramularia saxifragae Syd.)。(木来)来木菌绒孢(Mycovellosiella coni Y.L. Guo, sp. nov.)生于山茱萸科(Cornaceae)华尔特氏掠子木(Cornus walteri Wanger.)叶上。子实体生于叶背面。次生菌丝体表生。无子座。分生孢子梗1-3根从气孔伸出或作为侧枝单生于表生菌丝上,近无色,分枝,曲膝状,1-2个隔膜,5.0-50.0 × 2.5-4.0 μm。分生孢子圆柱形,无色,链生并具枝链,0-4个隔膜,6.5-45.0 × 2.0-4.0 μm。在山茱萸科尚无菌绒孢属的报道,且该菌与已报道的尾孢属菌形态特征也不同,故定为新种。五味子色链隔孢(Phaeoramularia schisandrae Y.L. Guo, sp. nov.)生于五味子科(Schisandraceae)五味子[Schisandra chinensis (Tunz.) Baill.]叶上,子实体生于叶背面。菌丝体内生。具子座。分生孢子梗紧密簇生,浅青黄褐色,不分枝,曲膝状,1-5个隔膜,20.0-75.0 (-95.0) × 4.0-5.0 μm。分生孢子圆柱形,近无色,链生并具枝链,1-4个隔膜,15.0-40.0 × 3.0-4.0 μm。五味子科既无尾孢菌属也无色链隔孢属的报道。文中为新种提供了拉丁文简介、描述和图,新记录种进行了简要描述。研究的标本保藏在中国科学院微生物研究所真菌标本室(HMAS)。     

Septoria的新种和国内新记录种

作者在1987-1991年间从东北地区收集和采集Septoria真菌标本221份,鉴定出Septoria 84种,其中2个新种:Septoria dioscorical Lu Guo-zhong et Bai Jin-kai和Septoria saposhinikoviae Lu Guo-zhong et Bai Jin-kai,以及13个国内新记录种. Septoria属真菌的产孢方式为全壁芽生合轴式(holoblastic sympodial)。     

The effects of dissolved oxygen and aquatic surface respiration on the critical thermal maxima of three intermittent-stream fishes

Synopsis Critical thermal maxima (CTM) were determined for three species of fish in hypoxic (1.2 mg l^-1), normoxic (7 mg l^-1) and hyperoxic (12 mg l^-1) oxygen tensions. All fish were acclimated to 30°C under a regulated photoperiod of 12:12. During each CTM determination, one-half of the test fish were allowed free access to the surface (to permit aquatic surface respiration) while the remaining one-half were denied access to the surface. Under hypoxic conditions, CTMs of Fundulus notatus, Notropis lutrensis and Pimephales vigilax given access to the surface were significantly higher than those of conspecifics without access to the surface. With access to the surface, all species had significantly lower CTMs under hypoxic conditions than under normoxic and hyperoxic conditions. CTMs measured under normoxic and hyperoxic conditions were not different for any of the test species. Under all comparable oxygen tensions with surface access, F. notatus had the highest CTM, N. lutrensis intermediate and P. vigilax had the lowest CTM. The critical oxygen concentration for N. lutrensis during CTM determinations occurred between 1.2 and 2 mg l^-1.     

Species of Pleuroxus (Anomopoda,Chydoridae) from the subantarctic islands and southernmost South America: a partial unravelling of the Pleuroxus aduncus problem

Whereas previously all populations of Pleuroxus (now P.) known from the subantarctic islands and southernmost South America were considered to belong to a subspecies of P. aduncus (described from France), now there are five distinct species, only one of which resembles P. aduncus to any significant extent, but even it is a good species. Thus, the taxa are all distinctly different, and none of them could possibly be considered an infraspecies of P. aduncus sens. str. P. macquariensis from Macquarie Island and P. paroplesius and P. varidentatus from South America are new. Of the five species, P. varidentatus resembles P. aduncus most closely, but is separated from it by a number of significant characters. P. wittsteini is presently known from five islands in the south Indian Ocean, but there is considerable uncertainty as to whether all these populations really are the same taxon, because they differ somewhat in the shape of the labrum and in the intensity of sculpturing of the carapace and head. P. scopuliferus from South America is the most distinctive species of the group, having 9 gnathobasic filter setae on trunklimb III instead of the usual 8, a weak ridge on the shell, and a recurved rostrum extending beyond the tip of the labrum. No species of Pleuroxus (or of P., another subgenus of animals formerly assigned simply to Pleuroxus are known from the islands in the Scotia Arc between South America and Antarctica. The patterns of distribution cannot be explained by an on-going passive dispersal of resting eggs. No populations of species on the subantarctic islands are known from any of the southern land masses. Conditions on these islands intuitively must have been more severe during the glacial ages than during the present interglacial, suggesting that any anomopods present were eliminated during the severe glacial periods. Yet, the presence of isolated populations of endemic species on some islands and the complete lack of Pleuroxus on others (e.g. those in the Scotia Arc) argues that conditions, although more severe, still provided opportunities for the maintenance of active populations. Moreover, the morphological differences between populations of P. wittsteini on islands from a few hundred to several thousand kilometers apart likewise argue for genetic isolation over a very long period of time. Deceased     

华南吊灯花属(夹竹桃科)植物小志

通过野外调查、标本查阅及文献考证,订正了华南吊灯花属(Ceropegia Linn.)植物,将狭瓣吊灯花(C. angustilimba Merr.)从吊灯花(C. trichantha Hemsl.)的异名中予以恢复,提供了二者的形态描述,确认华南地区记录的柳叶吊灯花(C. salicifolia H. Huber)实为剑叶吊灯花(C. dolichophylla Schltr.)的错误鉴定,并提供了后者的形态描述。     

樟科植物柄锈菌补记

本文报告了樟科植物上的柄锈菌计巧种。其中有4个新种:四川山胡椒柄锈Puccinia linderae-setchuenensis sp. nov.,黄丹木姜子柄锈Puccinia litseae-elongatae sp. nov., 赛楠柄锈Puccinia nothaphoebes sp. nov.和湘楠柄锈Puccinia phoebes- hunanensis sp. nov二新种模式标本保藏在中国科学院微生物研究所真菌标本室。研究了已知种的模式标本,并在文中作了简要讨论。文中附有种的检索表。