5种相思树和尾巨桉人工林土壤养分和酶活性特征

为揭示固氮树种土壤养分转化的酶学机制,对固氮树种[厚荚相思(Acacia crassicarpa)、黑木相思(A. melanoxylon)、卷荚相思(A.cincinnata)、大叶相思(A.auriculiformis)和马占相思(A.mangium)]及非固氮树种尾巨桉(Eucalyptusurophylla×E.grandis)人工林的土壤养分含量、酶活性及其相关性进行研究。结果表明,相思林40～60cm土层的pH均高于尾巨桉林;5种相思林土壤各土层的TP、TK含量均低于尾巨桉林,而20～40 cm土层的TC、TN含量均高于尾巨桉林,黑木相思林和马占相思林各土层的有效养分均显著高于尾巨桉林(P0.05)。0～10 cm土层中,相思林的土壤酸性磷酸酶和纤维素酶活性均高于尾巨桉林,大叶相思林的土壤脲酶、蔗糖酶、纤维素酶和芳基硫酸酯酶活性显著高于尾巨桉林(P0.05),卷荚相思林的土壤脲酶、纤维素酶、几丁质酶和淀粉酶活性显著高于尾巨桉林(P0.05)。相关分析结果表明,土壤脲酶、蔗糖酶和几丁质酶活性与AP显著负相关(P0.05),蔗糖酶和纤维素酶活性与NH4+-N显著负相关(P 0.05),脲酶、纤维素酶、芳基硫酸酯酶与土壤TK显著负相关(P0.05),几丁质酶活性与TN含量呈显著正相关(P0.05),土壤淀粉酶活性与NH4+-N呈显著正相关(P 0.05),过氧化氢酶活性与土壤TK含量呈显著正相关。可见,与尾巨桉人工林相比,在我国南方退化山地引种相思树可提高土壤关键酶的活性,对土壤有效养分具有明显改良作用,有利于退化地土壤的生态修复及人工林长期生产力的维持。     

Biogeographic Patterns of Intertidal Macroinvertebrates and their Association with Macroalgae Distribution along the Portuguese Coast

Geographical patterns in the distribution of epifaunal crustaceans (Amphipoda, Isopoda and Tanaidacea) occurring with dominant macroalgal species were investigated along the Portuguese rocky coast. Three regions, each encompassing six shores, were studied. Algal species were selected according to their geographical distribution: Mastocarpusstellatus and Chondrus crispus (north); Bifurcariabifurcata (north-centre); Plocamiumcartilagineum and Cystoseiratamariscifolia (centre-south); Corallina spp. and Codiumtomentosum (entire coast). Multivariate techniques were used to test for differences in crustacean assemblage composition between sub-regions and host algal species. A clear gradient of species substitution was observed from north to south. Differences in abundance and diversity of epifaunal crustaceans were observed between southern locations and the remaining sites. Four species were recorded for the first time in the Portuguese coast. Among the 57 taxa identified, southern distribution limits were observed for three species and northern distribution limits were observed for four species. Interestingly, the observed geographical patterns in epifaunal abundance and diversity were not related with geographical changes in the indentity of the dominant algal species.     

Further report on object manipulation in non-human primates: A comparison within 13 species of the genusMacaca

Thirteen captive species of the genusMacaca were presented with certain non-edible objects and the subsequent manipulation was observed. The following results were obtained: (1) Thefascicularis group species displayed a great variety in rolling the manipulandum, which has been reported to be one of the actions characterizing cercopithecine species; (2) manipulating the object with one finger was typical of thesilenus-sylvanus andsinica groups, whereas use of the fingers moving opposably was common to all species ofMacaca; (3) secondary manipulations in relation to the wire-mesh were observed only inM. silenus, M. sinica, andM. nemestrina, whereas those in relation to water were common to allMacaca species; and (4) within-subgroup differences were great in thesilenus-sylvanus andsinica groups as compared to thefascicularis group.     

碎米荠超氧化物歧化酶基因家族成员的鉴定和分析

为了解碎米荠(Cardamine hirsuta)的SOD基因特征,对SOD家族成员的基因结构、染色体定位、系统进化关系进行了分析,对顺式作用元件和蛋白结构进行了预测,并利用qRT-PCR技术检测各家族成员的组织表达模式。结果表明,碎米荠基因组中共有10个SOD基因(ChSODs),包括6个Cu/Zn-SOD、3个Fe-SOD和1个Mn-SOD。编码的ChSODs蛋白有57~ 324个氨基酸,分子量为6 419.41~34 659.01 kDa,理论等电点为4.92~9.60;系统进化树分析表明,碎米荠的ChSOD与拟南芥的AtSOD的同源性较高;ChSODs在根、茎、叶中均有表达,且在叶中高表达,其中CARHR085500和CARHR256690在叶和茎中表达量较高;顺式作用元件预测表明,碎米荠SOD响应多种非生物胁迫,其中对ABA和低温胁迫较为敏感; ChSODs蛋白质的二级和三级结构具有差异性。这表明碎米荠SOD基因在抗氧化过程中发挥重要作用。     

Flavonoids in the leaves of twenty-eight polygonaceous plants

Flavonoids in the leaves of twenty-eight species belonging to the Polygonaceae were studied. Thirty-three kinds of flavonoids were isolated, and eighteen kinds were obtained as crystals. Quercetin glycosides were commonly found in the family. In the quercetin glycosides, 3-O-rhamnoside was most frequently found: 3-O-glucuronide is also distributed widely. Myricetin glycosides were rare. Methylated flavonols were found in some species of the sectionsEchinocaulon andPersicaria. Eleven kinds ofC-glycosylflavones were found in the present survey, andC-glycosylflavones were distributed in all species of the genusRheum and in almost all species of the section Tiniaria.Rumex Acetosella andPolygonum suffultum are exceptional, the former contains flavone glycoside and the latterC-glycosylflavones only, as main components.     

Isolation and characterization of regulatory mutations affecting the expression of the guaBA operon of Escherichia coli K-12

Summary We isolated strains of Escherichia coli K 12 in which the lac structural genes were fused to the structural genes of the guaBA operon. These strains were used to isolate regulatory mutations that increased the expression of the guaBA operon under normal repressing conditions as compared to the wild type parental fusion strain. Three classes of guaBA specific regulatory mutations were identified. Class I regulatory mutations were trans-acting and unlinked to the guaBA operon as shown by bacteriophage P1 transduction. Class II regulatory mutations were tightly linked to the guaBA operon, cis-dominant to the wild type allele in a cis-trans analysis and were regarded as control region mutations. Class III regulatory mutations were tightly linked to the guaBA operon and trans-recessive to the wild type allele in a cis-trans analysis. We have designated the locus responsible for the class III regulatory mutations as guaR. The guaR locus is tightly linked and was mapped to the counterclockwise side of the guaBA operon. The guaR locus is proposed to specify a trans acting regulatory element involved in the regulation of the guaBA operon.     

Antagonism against Rhizoctonia solani and fungitoxic metabolite production by some Penicillium isolates

A number of Penicillium isolates were recovered in association to Rhizoctonia solani strains pathogenic on tobacco and from soil on plates pre-colonized by the pathogen itself. Their antagonism toward R. solaniAG-2-1 was evaluated in dual cultures in vitro. Inhibition of growth was evident to some extent in most pairings, while hyphal interactions referable to mycoparasitic relationships were not observed. However, the occurrence of plasmolysis and/or vacuolisation and the induction of monilioid cells were indicative of the release of bioactive compounds. Therefore, production of fungitoxic metabolites was tested by adding concentrated culture filtrates of each Penicillium isolate to the growth medium of R. solani. Complete and lasting inhibition was incited by culture filtrates of some isolates belonging to P. brevicompactum, P. expansum, and P. pinophilum. Three purified compounds, respectively mycophenolic acid, patulin and 3-O-methylfunicone, which were extracted from culture filtrates, were able to inhibit R. solani in vitro. Their production was also detected in dual cultures of the same Penicilliumstrains with R. solani prepared in sterilized soil and when the Penicilliumstrains were cultured directly on R. solani mycelium harvested from liquid cultures. The possible role of such metabolites in antagonism of the above-mentioned Penicilliumspecies against R. solani is discussed.     

重楼属植物遗传多样性的SCOT标记

为评估重楼属植物的基因资源开发前景,初步探讨了SCOT标记技术在重楼属植物遗传多样性研究上的应用。采用目标起始密码子多态性(Start codon targeted polymorphism,SCOT)技术,对重楼属9个种40份材料进行基因组DNA多态性分析。结果表明:四川地区重楼属植物具有丰富的遗传多样性,40份供试材料可聚为4类:狭叶重楼单独聚为第一类;球药隔重楼、卵叶重楼、金线重楼及滇重楼聚为第二类;黑籽重楼与七叶一枝花聚为第三类;五指莲与毛重楼聚为第四类。说明SCOT标记能够对重楼属植物进行准确的分子鉴定,为重楼属植物的种类鉴定和种间的分类地位提供分子生物学依据,同时也为深入探究重楼皂苷合成关键酶基因定位研究提供重要参考。     

Microbial parasites associated with Tylenchulus semipenetrans in citrus orchards of Catalonia,Spain

Citrus orchards in Catalonia, Spain were surveyed to identify microbial parasites of Tylenchulus semipenetrans, and their distribution and density. Of 62 orchards, 48 were positively infested with the citrus nematode. Fungal strains were isolated from single eggs, females or second-stage juveniles of the citrus nematode in 69% of the infested orchards. The fungi identified in order of occurrence were Paecilomyces lilacinus, Fusarium solani, Fusarium spp., Cylindrocarpon cylindroides, Verticillium fungicola, Cladosporium cladosporioides, F. oxysporum, Veronaea botryosa, Sepedonium chrysospermum, Volutella ciliata, Exophiala pisciphila and Acremonium sp. Fungal parasitism was related directly to the number of females g^?1 of root and magnesium in the soil, and inversely, to the number of eggs g^?1 of root and phosphorus in the soil (R ²=0.8654; P<0.0001). Nematode trapping fungi were isolated from soil samples in 29% of the orchards, and Monacrosporium elegans, Arthrobotrys dactyloides, A. javanica, A. superba and A. oligospora var. microspora, were the species present. Endospores of the hyperparasite Pasteuria adhering to vermiform stages of T. semipenetrans were found in 50% of the orchards infested with the citrus nematode.     

Specificity of an ant-lycaenid interaction

Summary Many lycaenid butterflies are believed to be mutualists of ants — the butterfly larvae secrete sugars and amino acids as rewards for the ants, and the ants protect the larvae from predation or parasitism. We examined the specificity of the relationship between the lycaenid Plebejus argus and ants in the genus Lasius. Eggs were not attractive to Lasius ants until the emerging larvae had broken through the chorion. First instar larvae were palpated and picked up by Lasius workers and taken to the nest. First instars were mostly ignored by Myrmica sabuleti ants and they were rarely detected by Formica fusca. Older larvae were more attractive to Lasius than to the other ant genera. Pupae were very attractive to Lasius, moderately so to Myrmica, and were ignored by Formica fusca. Teneral adults were palpated by Lasius, but were attacked by Myrmica and Formica workers. We conclude that P. argus is a specialist associate of Lasius ants. Two populations of Plebejus argus were compared: one is naturally associated with Lasius niger, and the other with Lasius alienus. In reciprocal trials, larvae were slightly more attractive to their natural host ant species. Since test larvae were reared on a single host plant species in captivity, this differentiation probably has a genetic basis.     

Molecular and functional analysis of the ruv region of Escherichia coli K-12 reveals three genes involved in DNA repair and recombination

Summary Recombinant plasmids carrying ruvA, ruvB, or both were constructed and used to investigate the genetic defects in a collection of UV-sensitive ruv mutants. The results revealed that efficient survival of UV-irradiated cells depends on both ruvA and ruvB, and on a third gene, ruvC, located upstream of the ruvAB operon. Southern blotting analysis was used to locate insertions in ruv and to examine putative deletion mutants. Two Tn10 insertions were located to the region encoding ruvA. Since these insertions caused a deficiency in the activities of both ruvA and ruvB, we concluded that they must exert a polar effect on ruvB. Two putative ruv deletion mutants were shown to be the result of deletion-inversion events mediated during imprecise excision of Tn10. The relevant inversion breakpoints in these mutants were located to ruvA and ruvC.     

A Mariner-Like Transposable Element in the Insect Parasite Nematode Heterorhabditis bacteriophora

For the first time, mariner elements were found in insect parasitic nematodes. Full-length elements were isolated from the rhabditid Heterorhabditis bacteriophora. They were 1279 bp long, flanked by two 30-bp inverted repeats, and were able to encode a putative 358-amino acid transposase. These elements were present in about 30 copies in the H. bacteriophora genome, but their distribution among closely related Heterorhabditis and Steinernema genera was patchy. DNA and encoded peptide sequences of H. bacteriophora mariners showed greater similarity to the mariner of the coleopteran Carpelimus sp. than to the mariners of the rhabditid Caenorhabditis elegans. The possibility of horizontal transfer was investigated by examination of a host for Heterorhabditis nematodes, a beetle of the Phyllophaga sp. Mariner elements were found in this insect, but they were not very similar to the H. bacteriophora elements. Finally, the H. bacteriophora mariners formed a group with those of invertebrates, suggesting vertical transmission from a common ancestor. Received: 14 November 1997 / Accepted: 4 August 1998     

马尾松R2R3-MYB基因特征及进化和表达分析

MYB类转录因子在植物生长发育、代谢、应答生物胁迫和非生物胁迫的响应等生物过程发挥重要作用。为探究马尾松R2R3-MYB基因结构及功能,该研究以转录组数据为研究区域,从中筛选获得了17个马尾松R2R3-MYB基因,利用生物信息学对基因进行理化性质、系统进化树等分析,同时利用荧光定量PCR技术分析基因的组织特异性以及在花发育时期和非生物胁迫下的表达模式。结果表明：(1)17个PmMYBs亚细胞定位于细胞核,均无跨膜结构,且均含有Motif1、Motif2保守基序。系统发育进化树将马尾松PmMYBs划分为9个亚家族,且与火炬松、白云杉等裸子针叶植物关系较近。(2)17个基因均属于组成型表达,但在不同组织的表达量不同;所有基因均参与了花发育和非生物胁迫,不同基因在花发育不同时期的表达存在差异,有7个基因可能参与了雌雄性状转变;大部分基因响应非生物胁迫上调表达,但响应胁迫的时间存在差异;少数基因在胁迫中下调表达,尤其是PmMYB11基因在所有胁迫中均明显下调表达。该研究较系统地分析了马尾松R2R3-MYB基因的结构特征、系统进化及其在花发育时期和非生物胁迫下的表达模式,为深入探究马尾松R2R3...     

New evidence for the potential role of Culex pipiens mosquitoes in the transmission cycle of West Nile virus in Tunisia

Physiological and molecular characteristics of natural populations of Culex pipiens Linnaeus, 1758 (Diptera: Culicidae) were investigated to elucidate how this species is potentially involved in the transmission of West Nile virus in Tunisia. A total of 215 Cx. pipiens females from 11 breeding habitats were analysed in the laboratory to estimate autogeny and stenogamy rates. They were tested individually for the locus CQ11 to distinguish between the two Cx. pipiens forms, pipiens and molestus. All tested Cx. pipiens populations were stenogamous. Females from underground breeding sites were all autogeneous, whereas females from above‐ground habitats were mostly anautogeneous. Of all the females tested, 59.7% were identified as pipiens, 22.4% as molestus, and 17.9% as hybrid pipiens/molestus. Furthermore, both Cx. pipiens forms and their hybrids were found to co‐occur in sympatry in all sites. The results of this study represent the first evidence that both Cx. pipiens forms and their hybrids are present in Tunisia. Because hybrids able to act as bridge vectors are present in all studied habitats, Tunisia can be considered to have a high degree of receptivity for the establishment of West Nile virus zoonotic cycles.     

Comparative genomics of Bifidobacterium species isolated from marmosets and humans

The genus Bifidobacterium is purported to have beneficial consequences for human health and is a major component of many gastrointestinal probiotics. Although species of Bifidobacterium are generally at low relative frequency in the adult human gastrointestinal tract, they can constitute high proportions of the gastrointestinal communities of adult marmosets. To identify genes that might be important for the maintenance of Bifidobacterium in adult marmosets, ten strains of Bifidobacterium were isolated from the feces of seven adult marmosets, and their genomes were sequenced. There were six B. reuteri strains, two B. callitrichos strains, one B. myosotis sp. nov. and one B. tissieri sp. nov. among our isolates. Phylogenetic analysis showed that three of the four species we isolated were most closely related to B. bifidum, B. breve and B. longum, which are species found in high abundance in human infants. There were 1357 genes that were shared by at least one strain of B. reuteri, B. callitrichos, B. breve, and B. longum, and 987 genes that were found in all strains of the four species. There were 106 genes found in B. reuteri and B. callitrichos but not in human bifidobacteria, and several of these genes were involved in nutrient uptake. These pathways for nutrient uptake appeared to be specific to Bifidobacterium from New World monkeys. Additionally, the distribution of Bifidobacterium in fecal samples from captive adult marmosets constituted as much as 80% of the gut microbiome, although this was variable between individuals and colonies. We suggest that nutrient transporters may be important for the maintenance of Bifidobacterium during adulthood in marmosets.     

Canopy disturbance patterns and regeneration of Quercus species in two Ohio old-growth forests

This study was conducted to determine the abundance of Quercus species, the spatial pattern of Quercus regeneration, the current canopy disturbance pattern, and their interrelationship in two old-growth deciduous forests in Ohio (Goll Woods and Sears-Carmean Woods). Acer saccharum and Fagus grandifolia had the greatest density and basal area in both forests, yet the largest trees (by basal area) present at each site were Quercus spp. Quercus spp. appeared to be decreasing in abundance in both sites. Though Quercus seedlings were common, few Quercus saplings or subcanopy trees were present. The current disturbance regimes were dominated by small canopy gaps created by death of 1–2 trees; canopy gaps 100 m² in size were rare and only 2.5–2.8% of the forest area was covered by recognizable canopy gaps. No significant differences in the density of Quercus seedlings or saplings were found between gaps and non-gap areas at either site. Though no significant barrier to seedling establishment appeared to exist, the present disturbance regimes are not well suited for the growth of Quercus into the subcanopy size class or the recruitment of Quercus into the canopy. The most frequent gapmakers in Goll Woods were Tilia americana and Acer saccharum, and those in Sears-Carmean Woods were A. saccharum and F. grandifolia. The species most frequent as gap fillers were A. saccharum (in both sites) and F. grandifolia (in Goll Woods). These results suggest that A. saccharum will continue to increase in abundance, and Quercus decrease in abundance, in these two old-growth stands.     

Vertical distribution of marine fungi onRhizophora apiculata at Morib mangrove, Selangor, Malaysia

Studies on the vertical distribution of marine fungi in aRhizophora apiculata mangrove stand in Morib, Selangor were carried out in June 1993 and June to November 1997. Prop roots, subterranean roots and overhanging branches ofR. apiculata were collected from three intertidal levels namely upper (high water mark), middle and lower. Fifty-three species were recorded including 39 ascomycetes, 13 deuteromycetes and one basidiomycete. The most common fungi wereHalocyphina villosa (frequency occurrence 21%),Kallichroma tethys (20%),Lulworthia grandispora (18%),Leptosphaeria australiensis (16%),Julella avicenniae (15%) andMassarina ramunculicola (13%). The fungi were found to be vertically zoned, some were limited to the upper level such asPyrenographa xylographoides, Julella avicenniae andAigialus grandis or lower level such asTrichocladium achrasporum andT. alopallonellum, while only five species showed a broader distribution, being present at all levels:Leptosphaeria australiensis, Halocyphina villosa, Cryptovalsa sp.,Lulworthia grandispora andLulworthia sp. The greatest diversity of marine fungi were collected from the middle level with a Shannon Diversity Index of 5.9 while the Jaccard Similarity Index of 2.25 indicated that the upper and middle levels were the most similar in terms of species composition. Fungi with certain characteristics were also limited to particular levels, for example, carbonaceous and superficial ascomata were confined above mean tide while membranous walls and immersed ascomata were common below mean tide level.     

Latitudinal differentiation in the effects of the toxic dinoflagellate Alexandrium spp. on the feeding and reproduction of populations of the copepod Acartia hudsonica

Blooms of the dinoflagellate Alexandrium spp. increase in their frequency, toxicity and historical presence with increasing latitude from New Jersey (USA) to the Gaspé peninsula (Canada). Biogeographic variation in these blooms results in differential exposure of geographically separate copepod populations to toxic Alexandrium. We hypothesize that the ability of copepods to feed and reproduce on toxic Alexandrium should be higher in copepods from regions that are frequently exposed to toxic Alexandrium blooms. We tested this hypothesis with factorial common environment experiments in which female adults of the copepod Acartia hudsonica from five separate populations ranging from New Jersey to New Brunswick were fed toxic and non-toxic strains of Alexandrium, and the non-toxic flagellate Tetraselmis sp. Consistent with the hypothesis, when fed toxic Alexandrium we observed significantly higher ingestion and egg production rates in the copepods historically exposed to toxic Alexandrium blooms relative to copepods from regions in which Alexandrium is rare or absent. Such differences among copepod populations were not observed when copepods were fed non-toxic Alexandrium or Tetraselmis sp. These results were also supported by assays in which copepods from populations both historically exposed and naïve to toxic Alexandrium blooms were fed mixtures of toxic Alexandrium and Tetraselmis sp. Two-week long experiments demonstrated that when copepods from populations naïve to toxic Alexandrium were fed a toxic strain of Alexandrium they failed to acclimate, such that their ingestion rates remained low throughout the entire two-week period. The differences observed among populations suggest that local adaptation of populations of A. hudsonica from Massachusetts (USA) to New Brunswick (Canada) has occurred, such that some populations are resistant to toxic Alexandrium.     

Mutations affecting regulation of the anabolic argF and the catabolic aru genes in Pseudomonas aeruginosa PAO

Summary The nucleotide sequence required for a fully functional promoter and operator of the Pseudomonas aeruginosa argF gene (argF _po), the arginine-repressible gene for anabolic ornithine carbamoyltransferase, was defined within a 160 by region. The streptomycin (Sm) resistance genes strAB of plasmid RSF1010 were fused to argF _po. This construct in P. aeruginosa strain PAO conferred resistance to Sm. Mutants of strain PAO were selected which were resistant to Sm in the presence of arginine due to constitutive expression of argF _po —strAB. These mutants were designated argR. They were unable to grow or grew poorly on arginine or ornithine as the sole carbon and nitrogen source. This growth defect (Aru^–/Oru^– phenotype) was correlated with a reduced level of N-succinylornithine aminotransferase, an enzyme participating in the major aerobic pathway for arginine and ornithine catabolism in this organism. The argR mutants were classified into four groups by transduction analysis and three argR mutations were mapped on the PAO chromosome. argR9901 and argR9902 were co-transducible with car-9 (at 1 min) and thus close to the oru-310 locus; argR9906 was localized in the oruI (=aru) gene cluster (67 min). Some aru mutants, which have been isolated previously and which produce very low amounts of all enzymes in the arginine succinyltransferase pathway, were unable to repress the argF gene in an arginine medium. Thus, P. aeruginosa PAO appears to have multiple genes that are involved in the regulation of both the anabolic argF and the catabolic aru genes.Abbreviations Arg^– arginine auxotrophy - Aru arginine utilization - Oru ornithine utilization