不同种苏铁珊瑚状根内生微生物多样性及适应性研究

【目的】苏铁(Cycassp.)是珍稀濒危树种,能在干热河谷中长期稳定生存的原因可能与珊瑚状根内生微生物有密切关系。不同种苏铁在同一生境下其珊瑚状根内生微生物种类和群落组成存在怎样的差异性是本研究的科学问题。【方法】采用宏基因测序技术对四川省攀枝花公园内5种同属不同种苏铁珊瑚状根进行了分子鉴定,分析了苏铁间微生物类型、功能基因和代谢通路过程的差异性。【结果】公园内不同苏铁的珊瑚状根内生微生物的优势类群在门水平上基本相同,但相对丰度有差异性。在真菌界水平上的优势类群为担子菌门(Basidiomycota)、子囊菌门(Ascomycota)、球囊菌门(Glomeromycota)和隐真菌门(Cryptomycota),在细菌界水平上的优势类群为蓝细菌门(Cyanobacteria)、变形菌门(Proteobacteria)、厚壁菌门(Firmicutes)、螺旋体门(Spirochaetes)和放线菌门(Actinobacteria)。不同种的苏铁在真菌界和细菌界的微生物群落相对丰度存在一定差异。蓝细菌门在篦齿苏铁、攀枝花苏铁、华南苏铁和贵州苏铁中的相对丰度远高于宽叶苏铁,而放线菌门和球囊...     

Cytogenetics of Brazilian species of Bromeliaceae

This paper presents the mitotic chromosome numbers of 18 species of Bromeliaceae. The diploid number 2n = 50 was observed in Aechmea comata, A. caudata, A. correia‐araujoi, A. recurvata, A. marauensis, A. bicolor, A. pineliana, Hohenbergia catingae, H. blanchetti, Alcantarea imperialis, Al. nahoumi, Neoregelia tenebrosa, Nidularium lyman‐smithii, N. scheremetiewii, N. innocentii var. innocentii, and N. innocentii × Neoregelia johannis hybrid, whereas 2n = 34 was observed in Cryptanthus maritimus and C. warren‐loosei. All of the determinations presented in this study are previously unpublished, except A. comata and H. catingae. These results confirm x = 25 as the basic number for the family and x = 17 as a secondary basic number probably generated by decreasing dysploidy. © 2008 The Linnean Society of London, Botanical Journal of the Linnean Society, 2008, 158 , 189–193.     

Seasonal study of the fungal biota of the fur of dogs

During a one year period, 944 dogs from the Municipal kennel of Barcelona were examined to detect animals with suspected dermatophytosis. Only a few animals (1.8%) presented skin lesions but none of them had dermatophytosis. A representative number of dogs without visible skin lesions (n=172), selected at random, were used to carry out a seasonal study of the mycobiota of their fur. Fifteen isolates belonging to the genera Microsporum and Trichophyton were isolated from 14 of the 172 (8.1%) dogs without lesions. The identity of these fungi was Microsporum gypseum (6/15), Trichophyton terrestre (4/15), M. canis (2/15), M. cookei (2/15) and Trichophyton ajelloi (1/15) (one strain each of M. gypseum and T. ajelloi were isolated from one dog). Species of Penicillium (% prevalence=89.5%), Alternaria (86.6%), Cladosporium (84.9%), Aspergillus (77.3%), Scopulariopsis (65.7%) and Chrysosporium (64.5%) were the most prevalent. No significant differences in the fungal biota were observed with respect to age, gender, hair length or between mixed and pure breed dogs. A large number of isolates, including species belonging to the genera Beauveria, Chrysosporium, Malbranchea and Scopulariopsis, that macroscopically and/or microscopically resemble dermatophytes and may be mistaken for them, produced a red color change in Dermatophyte Test Medium. No significant seasonal difference was detected among the isolates belonging to the the most frequently encountered genera, with the exception of Scopulariopsis (higher in summer and autumn) and Chrysosporium (higher in summer). Species from other genera, with lower occurrence also presented significant differences in their seasonal distribution. Arthrinium, Aureobasidium, Chaetomium and Phoma spp. presented maximum prevalence peaks in spring, Fusarium, Paecilomyces, Phoma and Rhizopus spp. in summer and Geotrichum and Mucor spp. in autumn. The Microsporum and Trichophyton species were more frequently isolated in summer.     

Conservation of upstream regulators of scute on the notum of cyclorraphous Diptera

Bristles on the notum of many cyclorraphous flies are arranged into species-specific stereotyped patterns. Differences in the spatial expression of the proneural gene scute correlate with the positions of bristles in those species looked at so far. However, the examination of a number of genes encoding trans-regulatory factors, such as pannier, stripe, u-shaped, caupolican and wingless, indicates that they are expressed in conserved domains on the prospective notum. This suggests that the function of a trans-regulatory network of genes is relatively unchanged in derived Diptera, and that many differences are likely to be due to changes in cis-regulatory sequences of scute. In contrast, in Anopheles gambiae, a basal species with no stereotyped bristle pattern, the expression patterns of pannier and wingless are not conserved, and expression of AgASH, the Anopheles proneural gene, does not correlate in a similar manner with the bristle pattern. We discuss the possibility that independently acting cis-regulatory sequences at the scute locus may have arisen in the lineage giving rise to cyclorraphous flies.     

河滨湿地不同植物群落根系分布特征与土壤理化性状的关系——以黄河中游荥阳段为例

在黄河中游郑州荥阳段,选择了5种河滨湿地植物群落进行根系和土壤性状特征研究,以期阐明不同植物群落的根系分布规律与土壤性状的关系,为河滨湿地植物群落组成以及土壤质量恢复提供科学参考。结果表明(1)在0—40 cm土层,根生物量密度与根长密度的平均值均表现为：芦苇群落(Phragmites australis)和芦苇-狗牙根(Cynodon dactylon)群落均大于芦苇-拂子茅(Calamagrostis epigeios)-狗牙根群落、拂子茅-狗牙根群落、拂子茅-狗牙根-水莎草(Juncellus serotinus)群落。拂子茅-狗牙根、芦苇-拂子茅-狗牙根、拂子茅-水莎草-狗牙根三种植物群落类型下根生物量密度、根长密度在0—20 cm表层土壤较大,芦苇群落和芦苇-狗牙根群落的根生物量密度、根长密度在10—40 cm的土层较大。(2)黄河河滨湿地芦苇群落、芦苇-狗牙根群落的土壤以粉粒为主,拂子茅-狗牙根群落、芦苇-拂子茅-狗牙根群落、拂子茅-狗牙根-水莎草群落的土壤主要以砂粒为主。在0—40 cm土层,芦苇群落、芦苇-狗牙根群落的土壤含水率、土壤有机质、有效氮和有效磷含量均显著高于...     

Phylogeny of slug species of the genus Arion: evidence of monophyly of Iberian endemics and of the existence of relict species in Pyrenean refuges

The Iberian Peninsula contains the majority of the Paleartic land slug species of the genus Arion, which exhibits diverse taxonomic problems. The present study investigated Arion taxonomy on the basis of analyses of the mitochondrial ND1 gene and nuclear internal transcribed spacer 1 (ITS1) sequences. The Iberian endemic species were monophyletically clustered in two divergent sister clades. The topotype specimens of Arion lusitanicus and the closely related species Arion nobrei and Arion fuligineus, as well as Arion hispanicus and Arion flagellus, were grouped into an ‘Atlantic’ clade, whereas Arion baeticus, Arion gilvus, Arion anguloi, Arion wiktori and Arion paularensis were included in a ‘Continental–Mediterranean’ clade. Calibration of mutation rate in the ND1 gene suggested that the divergence of these two clades occurred around the Pliocene–Pleistocene boundary, with subsequent speciation events during the Pleistocene. A group of ancestral and divergent endemic species with distribution centred in the Pyrenean mountain range (Arion molinae, Arion lizarrusti, Arion antrhacius and Arion iratii) arose in the Pliocene and survived through the Pleistocene in geographically confined small populations. Arion lusitanicus showed up to be polyphyletic: specimens, sampled outside the geographic range of the topotype in the north‐western Iberian Peninsula, were included in a non‐monophyletic clade together with the widely distributed species Arion ater and Arion rufus. The divergent species with a wide European distribution (Arion subfuscus, Arion hortensis, Arion fagophilus and Arion intermedius) were located in basal positions in all topologies. The evolutionary history of these slug species (highly sensitive to climatic factors, with capacity for both outcrossing and selfing, and with low dispersal ability) appears to have been moulded by Pliocene–Pleistocene climate events and by the rugged topography of southern Europe, giving rise to repeated cycles of population isolation during periods of glaciation alternating with interglacial expansions limited by geographic barriers.     

Organization of the origins of replication of the chromosomes of Mycobacterium smegmatis, Mycobacterium leprae and Mycobacterium tuberculosis and isolation of a functional origin from M. smegmatis

The genus Mycobacterium is composed of species with widely differing growth rates ranging from approximately three hours in Mycobacterium smegmatis to two weeks in Mycobacterium leprae. As DNA replication is coupled to cell duplication, it may be regulated by common mechanisms. The chromosomal regions surrounding the origins of DNA replication from M. smegmatis, M. tuberculosis, and M. leprae have been sequenced, and show very few differences. The gene order, rnpA-rpmH-dnaA-dnaN-recF-orf-gyrB-gyrA, is the same as in other Gram-positive organisms. Although the general organization in M. smegmatis is very similar to that of Streptomyces spp., a closely related genus, M. tuberculosis and M. leprae differ as they lack an open reading frame, between dnaN and recF, which is similar to the gnd gene of Escherichia coli. Within the three mycobacterial species, there is extensive sequence conservation in the intergenic regions flanking dnaA, but more variation from the consensus DnaA box sequence was seen than in other bacteria. By means of subcloning experiments, the putative chromosomal origin of replication of M. smegmatis, containing the dnaA-dnaN region, was shown to promote autonomous replication in M. smegmatis, unlike the corresponding regions from M. tuberculosis or M. leprae.     

Analysis of the rnc locus of Coxiella burnetii

A 3.2 kb EcoRI genomic DNA fragment of Coxiella burnetii was isolated by virtue of Its ability to suppress mucoidy in Eschertchia coli. Nucleotide sequence analysis revealed the presence of the genes homologous to rnc, era and recO of E. coli. Suppression of capsule synthesis, measured by β-galactosidase expression in Ion cps-lac fusion strains of E. coli, is caused by gene-dosage effects of the plasmid-borne rnc genes of either C. burnetii or E. coli. The rnc gene of C. burnetii complemented rn– E. coli hosts for lambda plaque morphology and stimulation of lambda N gene expression. We also demonstrated heterologous complementation of an E coli strain defective for the expression of Era, an essential protein in E. coli, using the plasmid-borne C. burnetii era. Under the control of the bacteriophage lambda P_L promoter, this 3.2 kb EcoRI DNA fragment directed the synthesis in E. coli of three proteins with approximate molecular masses of 35,27 and 25 kDa. Antibodies against purified E. coli Era protein cross-reacted with the 35 kDa protein of C. burnetii on Western blots.     

Characterization of S tester lines in Brassica oleracea: polymorphism of restriction fragment length of SLG homologues and isoelectric points of S-locus glycoproteins

 Forty three S tester lines of Brassica oleracea were characterized using DNA and protein gel-blotting analyses. DNA gel-blot analysis of HindIII-digested genomic DNA with class-I and class-II SLG probes revealed that 40 lines could be classified as class-I S haplotypes while three lines could be classified as class-II S haplotypes. The band patterns in the S tester lines were highly polymorphic. Although the S tester lines typically showed two bands corresponding to SLG and SRK in the analysis with the class-I SLG probe, only one band was observed in the S ²⁴ homozygote. This band was identified as SRK, suggesting that this haplotype has no class-I SLG band. In the analysis using the class-II SLG probe, one plant yielded a different band pattern from the known class-II haplotypes, S ² , S ⁵ and S ¹⁵ . Unexpectedly, this plant was reciprocally cross-incompatible with the S ² haplotype. Therefore, it was designated as S ^2-b . We found an S ¹³ haplotype having a restriction fragment length polymorphism different from that of the S ¹³ homozygotes of the S tester line. These findings indicate that S homozygous lines with the same S specificity do not necessarily show the same band pattern in the DNA gel-blot analysis. Soluble stigma proteins of 32 S homozygotes were separated by isoelectric focusing and detected using anti-S ²² SLG antiserum. S haplotype-specific bands were detected in 27 S homozygotes but not in five S homozygotes, including the S ²⁴ homozygote. This is consistent with the observation that the S ²⁴ haplotype had no SLG band. Received: 13 July 1998 / Accepted: 29 September 1998     

Characterization of the fixABC region of Azorhizobium caulinodans ORS571 and identification of a new nitrogen fixation gene

Summary The fast growing strain, Azorhizobium caulinodans ORS571, isolated from stem nodules of the tropical legume Sesbania rostrata, can grow in the free-living state at the expense of molecular nitrogen. Five point mutants impaired in nitrogen fixation in the free-living state have been complemented by a plasmid containing the cloned fix-ABC region of strain ORS571. Genetic analysis of the mutants showed that one was impaired in fixC, one in fixA and the three others in a new gene, located upstream from fixA and designated nifO. Site-directed Tn5 mutagenesis was performed to obtain Tn5 insertions in fixB and fixC. The four genes are required for nitrogen fixation both in the free-living state and under symbiotic conditions. The nucleotide sequence of nifO was established. The gene is transcribed independently of fixA and does not correspond to fixX, recently identified in Rhizobium meliloti and R. leguminosarum. Biochemical analysis of the five point mutants showed that they synthesized normal amounts of nitrogenase components. It is unlikely that fixA, fixC and nifO are involved in electron transport to nitrogenase. FixC could be required for the formation of a functional nitrogenase component 2.     

Comparison of seed proteins of some representatives of the genusPisum from the point of view of their relationship comparison by disc electrophoresis

Ten taxa of the genusPisum were examined by disc electrophoresis in gels according to Davis and to Reisfeldet al. For evaluation of band patterns the Jaccard Index was applied. The results in both types of gels show thatPisum abyssinicum and especiallyP. fulvum have biochemically a relatively isolated position.Pisum elatius and its subspeciescaspicum andpalestinicum form a subgroup withP. cinereum;P. sativum var.zeylanicum and cv. Jupiter form another subgroup withP. syriacum. Our results are in good agreement with the results of Przybylskaet al. (with the exception ofP. cinereum) and also with immunoelectrophoretic analyses performed by Turkováet al. (1980), with the same exception.     

Occurrence of exotic eels in natural waters of South Korea

We surveyed the proportion of anguillid eel species inhabiting South Korea natural waters. From September 2014 to August 2015, 429 eels were collected in various habitats for identification using morphological features and DNA-based molecular methods. We found 424 Japanese eels (Anguilla japonica, 98.8%), two European eels (A. anguilla, 0.5%), one American eel (A. rostrata, 0.23%), one tropical eel (A. marmorata, 0.23%), and one short-finned eel (A. bicolor pacifica, 0.23%). Three (A. anguilla, A. rostrata, and A. bicolor pacifica) are exotic species to the natural waters of South Korea; this study is the first record of their distribution in this region. Specifically, A. anguilla was found in the Lake Soyang and Cheongpyeong, while A. rostrata was found only in the Lake Cheongpyeong, and A. bicolor pacifica was found in the Geum River estuary.     

Interactions of thePolycomb group of genes with homeotic loci ofDrosophila

Summary Members of thePolycomb (Pc) group of genes are required for the correct determination of segment identity, and are thought to be negative regulators of thebithorax andAntennapedia complexes. This hypothesis has been tested molecularly for only some members of thePc group. Here, we examine the distribution ofUltrabithorax (Ubx),Antennapedia (Antp), andSex combs reduced (Scr) proteins in the epidermis, central nervous system, and midgut of embryos homozygous for mutations in tenPc group genes. We show that zygotic loss of mostPc group genes causes ectopic expression ofUbx andAntp, but that there are differences in time and tissue-specificity. FivePc group mutations lack midgut constrictions and also exhibit ectopic or suppressedUbx expression and suppression ofAntp expression. Distribution ofAntp is upset earlier than distribution ofUbx in the central nervous system of everyPc group mutant affecting both genes. Loss of the zygotic products ofPolycomb, extra sex combs, andAdditional sex combs cause ectopic expression ofScr in epidermis, and allPc group genes exceptPsc have suppressedScr expression in the nervous system. These results are discussed with respect to the function of thePc group.     

Chromosomes of Syrphidae

In this report the karyotypes of 54 species of the tribe Milesiini and of four species of the tribe Myoleptini are described in detail with illustrations and idiograms. These species belong in the genera Lejota, Myolepta, Blera, Calliprobola, Criorhina, Hadromyia, Milesia, Somula, Sphecomyia, Spilomyia, Syritta, Temnostoma, Tropidia and Xylota. Six species have 2n = 8 chromosomes, 35 have 2n = 10 (including Xylota nemorum which has about 20 extra microchromosomes in some specimens), 15 have 2n = 12, one has 2n = 14, and Somula decora has 2n = 10 large chromosomes plus about eight microchromosomes. The mean total complement length (TCL) for 347 complements analysed in these tribes was 53.7 but there is great variation between TCL's of complements analysed even from a single fly. Karyotypes of species of Myolepta in the Myoleptini resemble in certain respects those of species of Tropidia in the Milesiini. Our observations support Currran's transfer of Lejota cyanea to the Milesiini. The 2n = 12 karyotypes of species of Blera, Criorhina, Lejota, Milesia, and to a lesser extent Sphecomyia, have some features in common. Spilomyia species have rather distinct 2n = 10 karyotypes. Certain species in Calliprobola, Syritta and Hadromyia are karyologically similar to some species of the genus Xylota in which species studied fall into fairly distinct karyological groups. These observations provide clear evidence of the accumulation of karyotypic variations in the origin of species in these two tribes.     

Structural Analysis of an Extracellular Polysaccharide of Porodisculus pendulus

The aroL gene, encoding shikimate kinase of Brevibacterium lactofermentum, a coryneform glutamic acid-producing bacterium, was cloned. Recombinant plasmids containing the aroL gene caused elevated levels of shikimate kinase synthesis in B. lactofermentum. It was found that in addition to the aroL gene, the aroB and aroE genes, encoding dehydroquinate synthase and shikimate dehydrogenase, respectively, also existed on these recombinant plasmids, in complementation tests with various Escherichia coli and B. lactofermentum aromatic amino acid auxotrophs. The aroL, aroB and aroE genes of B. lactofermentum are located closely on the cloned DNA fragment, in that order. It was shown that at least these three aro genes form a cluster on the chromosome of B. lactofermentum.     

林火对植物根围丛枝菌根真菌多样性的影响

林火是森林生态系统的一种主要干扰因子,以青岛市三标山林火迹地为研究对象,采集荆条(Vitex negundo)、胡枝子(Lespedeza bicolor)、花木蓝(Indigofera kirilowii)、青花椒(Zanthoxylum schinifolium)和野青茅(Deyeuxia arundinacea)5种优势植物根围土壤,研究不同林火强度对丛枝菌根(AM)真菌多样性的影响。结果表明,AM真菌侵染率和孢子密度随火灾强度的加强而降低;非过火区植物根围土壤中,分离鉴定出AM真菌3属11种,轻度过火区分离鉴定出AM真菌3属10种,中度过火区分离鉴定出AM真菌3属9种,重度过火区分离鉴定出AM真菌3属8种。过火区AM真菌种丰度低于非过火区。过火区和非过火区AM真菌的重要值和优势种不同,非过火区植物根围的优势种是地球囊霉(Glomus geosporum)、台湾球囊霉(G.taiwanensis)、分支巨孢囊霉(Gigaspora ramisporophora)、极大巨孢囊霉(Gi.gigantean)、福摩萨球囊霉(G.formosanum)、悬钩子球囊霉(G.rubiforme)、柯氏无梗囊霉(Acaulospora koskei)和松蜜无梗囊霉(A.thomii);轻度过火区植物根围的优势种是地球囊霉和台湾球囊霉;中度过火区的是台湾球囊霉和地球囊霉(野青茅除外);重度过火区植物根围的优势种是地球囊霉。不同强度的过火区对AM真菌群落组成有不同程度的影响。认为林火降低植物根围土壤中AM真菌多样性。     

Costs of Predator Avoidance Reduce Competitive Ability of Daphnia

Large-sized Daphnia hyalina×galeata hybrid and small-sized Ceriodaphnia reticulata were raised together for 3 weeks in thermally stratified flow-through tubes ('plankton organ'), in the presence and the absence of fish kairomone, and their relative performance was monitored, as indicated by the populations' growth rates (r). In the kairomone-free medium, D. hyalina grew faster than C. reticulata; the presence of kairomone reversed this ratio, producing relatively higher r in C. reticulata. The simulated fish presence reduced growth in D. hyalina population also when it was separated from the competitor, while growth in C. reticulata was altered by the kairomone only in the presence of Daphnia. It is suggested that costs of surface avoidance in Daphnia can reduce its competitive superiority to small-sized cladocerans, permanently dwelling at the surface.     

Characterisation of the FAM69 family of cysteine-rich endoplasmic reticulum proteins

Myo-inositol is one of the major organic osmolytes in the brain and the kidney. The accumulation of intracellular organic osmolytes allows cells to regulate intracellular osmolality without altering cytoplasmic ionic strength and to adapt to hyperosmotic conditions. Two types of myo-inositol transporters, sodium/myo-inositol transporter and H⁺/myo-inositol transporter (HMIT), have been identified. Sodium/myo-inositol transporters are induced by osmotic stress and might be involved in the intracellular accumulation of myo-inositol in mammals. The role of HMIT, however, remains unknown. In the present study, we characterized three Caenorhabditis elegansHMIT genes, hmit-1.1, hmit-1.2, and hmit-1.3. hmit-1.1 was expressed in the intestine, and hmit-1.2 was expressed in the glia and the excretory canal, which is an osmotic regulatory organ that is functionally analogous to the kidney. hmit-1.3 was expressed in the intestine and the glia. The expression of hmit-1.1 and hmit-1.2 but not hmit-1.3, was markedly induced under hyperosmotic conditions. Animals with mutant hmit-1.1 and hmit-1.2 were hypersensitive to osmotic stress. The defects of hmit-1.1 and hmit-1.2 mutants were rescued by hmit-1.1 and hmit-1.2 transgenes, respectively, and by modified human HMIT. In human cell lines, HMIT expression was induced in hyperosmotic conditions. These findings indicate that the C. elegans HMIT family has a crucial role in the osmoprotective response.