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1.
In an extended study on the biodiversity of rock-dwelling bacteria, the colony and cell morphology, physiology, protein patterns,
and 16S rDNA sequences of 17 bacterial strains isolated from different surfaces of rocks, stones, and monuments and from various
geographical locations were characterized. All except one strain, which was found to be a Bacillus, were members of the order Actinomycetales. The majority of the strains either were closely related to Geodermatophilus obscurus, which was also analyzed in this study, or formed a closely related sister taxon. All of these strains were isolated from
the surface of marble in Namibia and Greece and from limestone from the Negev desert, Israel. One strain, G10, of Namibia
origin was equidistantly related to Geodermatophilus obscurus, Frankia alni, Sporichthya polymorpha, and Acidothermus cellulolyticus. Three strains from rock varnish in the Mojave desert, California, were found to be highly related to Arthrobacter (formerly Micrococcus) agilis. All clusters could be confirmed from results of studies on morphological and physiological properties and from banding patterns
of whole cell proteins. Based on the results of tests, four additional strains were assigned to the lineage defined by strain
G10.
Received: 16 October 1995 / Accepted: 4 April 1996 相似文献
2.
Lyngbya majuscula is a filamentous marine cyanobacterium with a worldwide distribution in temperate and tropical regions to a depth of 30 m. Over 70 chemicals have been isolated and characterised from this organism, many of which are biologically active. Previously, L. majuscula has been reported as implicated in negative health outcomes only in Hawaii and Okinawa. Recently large blooms of L. majuscula have occurred with increasing repetition in the Moreton Bay region as well as other areas along the Australian coastline.Lyngbya toxin A (LA) and debromoaplysiatoxin (DAT) were found in samples of L. majuscula collected from Eastern Moreton Bay and North Deception Bay, Queensland, Australia, respectively. Samples of L. majuscula were also obtained from West Maui, Hawaii and the freshwater Lyngbya wollei from Florida. A quantitative measure of the irritant effects of the chemicals found in L. majuscula was made using a mouse ear swelling test. The relative toxicities of two purified toxins, LA and DAT, were examined. These were found to produce swelling to a similar extent. The time course of inflammation and histopathological results were also similar for the two purified toxins. Less than 1 μg per ear of either toxin or a mixture (1:1) of the two toxins caused a measurable increase in ear thickness. When toxins were combined (1:1) there was an additive, not synergistic effect. Increases in ear thickness occurred within 15 min. Crude extracts of L. majuscula from Moreton Bay were also applied to mice ears. The effect of crude extracts from Eastern Moreton Bay was not fully explained by the measured LA content, suggesting other toxin(s) and/or modulating factors were present. The toxic effects of L. majuscula containing DAT from North Deception Bay were explained by the concentrations measured. Some samples of L. majuscula containing no measurable quantities of LA or DAT were found to exert an inflammatory response. This response had a different time course to the response produced by LA or DAT. 相似文献
3.
The compositions of carotenoids, chlorophylls and lipids at four depths in Ace Lake have been determined as a means of studying the vertical zonation of species in the lake and for comparison with the lipids found in the bottom sediments. The four major species of phytoplankton found in the lake were identified by electron microscopy. The most abundant phytoplankter was Pyramimonas gelidicola McFadden (Chlorophyta, Prasinophyceae) which occurred in greatest numbers at 10 m, the base of the oxylimnion. The pigments and lipids at this depth were mainly derived from this alga. At 11 m (the top of the anoxylimnion) only traces of lipids and pigments attributable to P. gelidicola were found, indicating only limited settling of algal cells through to the anoxylimnion, at least in summer. The pigments at 11 m were dominated by bacteriochlorophylls c derived from green photosynthetic bacteria Chlorobium spp. These pigments were also abundant at 23 m suggesting the presence of intact bacterial cells which had settled out from higher in the water column. Major non-polar lipid classes in the sediments included sterols, alcohols, hydrocarbons and an unusual suite of very long-chain unsaturated ketones and esters which have not previously been reported from antarctic environments. Several novel compounds, not found previously in either sediments or organisms, are reported. These include tri- and tetra-unsaturated straight-chain C 39 methyl ketones and C 40 ethyl ketones and the methyl ester of a tetra-unsaturated straight-chain C 36 fatty acid. The distributions of lipids in the sediment were markedly different from those in the water column indicating extensive bacterial degradation and recycling of labile lipids. 相似文献
4.
We documented major changes in the zooplankton community of Flathead Lake
following the appearance of Mysis relicta. The three
common cladocerans found in the lake decreased in abundance, most notably
Daphnia longiremis which disappeared from the lake.
Copepods were also affected by M.relicta, especially
Diacyclops thomasi which decreased in abundance by an
order of magnitude. The only macrozooplankton species which seemed to
benefit from the presence of M.relicta was
Leptodiaptomus ashlandi. The varied responses of
dominant zooplankton species appeared to be the result of a combination of
factors. Laboratory feeding studies indicate that
M.relicta preferred Cladocera over Copepoda, with the
following order of feeding preference: Bosmina longirostris
> D.longiremis >, Daphnia thorata > L.ashlandi
> D.thomasi. The two zooplankton species which declined
most following the appearance of M.relicta showed the
greatest degree of habitat overlap with M.relicta. Daphnia
longiremis and D.thomasi, together with
M.relicta, are cold stenotherms and were concentrated
in the hypolimnion during the summer. Finally, another trait shared by
D.longiremis and D.thomasi was
the absence of a diapause stage, which made them vulnerable to predation by
M.relicta throughout the year.
相似文献
5.
The sale of non-cultivated plants poses a real threat to the survival of a large number of plant species. On the other hand,
the fact that a given plant has become a traded item is an important lead in the effort to investigate plants for the purpose
of discovering novel secondary metabolites that may have marketable properties. This report is largely based on the investigations
of plants collected from vendors of medicinal plants. The identification is based on botanical specimens derived from the
purchased plant parts either by growing them in a garden or through micropropagation using tissue culture techniques. Bulbine species yielded novel phenyl anthraquinones and isofuranonaphthoquinones, which were found to exhibit antiparasitic and antioxidant
properties. Scilla nervosa subsp. rigidifolia and Ledebouria graminifolia yielded twenty homoisoflavonoids and two xanthones. Bulbs derived from tissue culture based specimens of L. graminifolia contained all the compounds isolated from the marketed samples. Some of the homoisoflavonoids were found to possess activity
against colon and breast cancer cell lines. Rhus pyroides furnished six novel bichalcones some of which exhibited insect antifeedant, cytotoxic and antiproliferative activities. Structures
of the compounds described in this report were elucidated by spectroscopic means including HRMS and 1D-, and 2D-NMR experiments.
Interconversion of some of the phenyl anthraquinones was accomplished as part of their structure proof. The total synthesis
of three of the biflavonoids was achieved using a synthetic route which involves a microwave irradiation promoted Ulmann synthesis.
This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献
6.
The stored-product mite Suidasia medanensis has been found in human-provided habitats in Japan. The mite uses neral as the alarm pheromone, and also secretes (Z,E)- and (£,£)-farnesal, which were isolated from an astigmatid mite for the first time. On the other hand, S. medanensis is the only mite out of fifteen species investigated so far that does not secrete volatile hydrocarbons along with the alarm pheromone, though 9-nonadecene and 6,9-nonadecadiene were found in a hexane extract of the mite. GC-MS, JH-NMR and 13C-NMR of the four isomers of synthetic farnesal, which were isolated by LC and preparative GLC, cleared up some confusion in the literature concerning the stereochemistry of this sesquiterpenoid. 相似文献
8.
SYNOPSIS Herpetomonas sp. was found repeatedly in the Malpighian tubules of laboratory-reared male and female Aedes aegypti and Aedes albopictus in Malaysia. The flagellates occurred irregularly, in batches, and were absent during long periods. The data suggest an exogenous source of infection for the mosquitoes, presumably from another insect, probably of another genus. Thirty to 40% of the flagellates of Aedes contained intracytoplasmic rod-shaped structures strongly resembling bacteria. These were found often in groups suggesting intracellular multiplication. They were passed to the Herpetomonas daughter cells during division. Parasitism of Aedes by Herpetomonas is extremely unusual, only one previous record, an inconclusive one, having been found. Parasitism by Herpetomonas containing bacterium-like rods has apparently never been reported. 相似文献
9.
The danaid butterfly Ideopsis similis, which occurs in the Ryukyu Islands, Japan, is a sedentary and monophagous species, whose larval food plant, Tylophora tanakae (Asclepiadaceae), is shared with the migratory and polyphagous danaid Parantica sita. The tachinid Sturmia bella is known to be a principal parasitoid of larval P. sita, whereas there have been no records of parasitization of I. similis by this tachinid. We conducted laboratory experiments and field surveys at seven sites in the Ryukyu Islands to determine how I. similis evades parasitization by this tachinid. We found eggs of S. bella at four sites and eggs and/or larvae of I. similis on the leaves of T. tanakae at all seven sites in the field survey. Out of 40 I. similis allowed to ingest S. bella eggs, 28 (70%) emerged as normal host adults and nine (22.5%) emerged as host adults with crippled wings. Only three (7.5%) died of parasitization in the pupal stage, whereas 27 (87%) of 31 P. sita given S. bella eggs yielded parasitoid flies and eventually died. Melanized dead larvae of S. bella were found in the abdomens of the I. similes adults that had been parasitized but did not yield parasitoid flies. When I. similis females parasitized by S. bella were released in a greenhouse with males, one of them laid fertile eggs. Out of 125 field‐collected I. similis adults, nine had melanized dipteran larvae within their abdomens, which were considered to be S. bella. These results demonstrate that I. similis has the ability to overcome parasitization by S. bella and develop into a fertile adult. It is possible that I. similis remains sedentary and monophagous because it has a strong defense mechanism against S. bella, whereas P. sita escapes from parasitization using its migratory and polyphagous capability. 相似文献
10.
Summary A lambda transducing phage (ED110) which carries the sex factor F surface exclusion genes, traS and traT, was characterized by both genetic and physiochemical techniques. The transducing segment consists of 5.2 kilobases of F tra DNA, and carries the carboxy-terminal onehalf of the upstream traG gene, as well as traS, traT, and the adjacent downstream gene traD. These tra proteins could be identified in infected UV-irradiated cells, and the major part of their synthesis was found to occur from the phage's late promoter p R under Q control.Lysogens for ED110 were induced and found to greatly overproduce the traT gene product (TraTp), an outer membrane protein normally found in about 20,000 copies per cell, to levels which exceeded the major outer membrane proteins. This led to the development of a simple purification procedure for TraTp, the most important step of which was the construction of an appropriate ompB derivative to eliminate the major outer membrane porin proteins, which have several physical properties in common with TraTp.Purified TraTp was added to mixtures of donor and recipient cells and found to inhibit mating. The specificity of this assay was demonstrated by using an R100-1 donor, which responds to a heterologous surface exclusion system, and by using an altered TraTp containing a missense amino acid substitution.A mechanism by which TraTp mediates surface exclusion is proposed. 相似文献
11.
The biochemical mechanisms were studied that determine different reactions of yeasts of different genera to two simultaneously imposed stressors, hypoxia and osmotic shock. For Candida lipolytica, these two stressors were antagonistic, which resulted in stimulation (and not suppression) of the growth of this yeast by NaCl (in a wide range of concentrations) under microaerobic conditions. The reaction of Malasseziasp. was different: the degree of halotolerance of this microorganism was lower under microaerobic conditions. An intervening reaction pattern was characteristic of Rhodotorula aurantiaca.These differences were found to be determined, above all, by the induction of a salt-resistant respiratory system (oxidase) in C. lipolytica, which could not be induced in Malassezia sp. In addition, the synthesis of catalase was enhanced in C. lipolytica, which provided for neutralization of the active forms of oxygen accumulating as a result of inhibition of other protective enzymes by salt. 相似文献
12.
—In 2015–2017, attendance of 15 invasive and 22 native species of herbaceous plants by ants was studied in 6 habitats in the environs of Kyiv (Ukraine). Altogether, 14 ant species were found, of which 12 were recorded on invasive plants and 9 on native plants; 8 aphid species were found on 8 invasive plant species. Five invasive plant species (Asclepias syriaca, Heracleum mantegazzianum, Oenothera biennis, Onopordum acanthium, and Amaranthus retroflexus) were found to be attractive to ants, with over a half of all the ant workers in all the habitats being recorded on them; besides, numerous colonies of 7 aphid species were also found on these plants. These invasive plants positively affect the structure of ant assemblages since the aphid colonies provide ants with food resource. The remaining 10 invasive plant species, including 5 transformer species, were poorly visited by ants and housed no aphid colonies, with the exception of Conyza canadensis on which the non-myrmecophilous aphid Uroleucon erigeronense (Thomas, 1878) was found. Two thirds of invasive plant species had a negative effect on the structure of ant assemblages because they replaced the native plants and thus reduced the trophic resources of aphids. 相似文献
13.
Specificity in the induced responses of tomato foliage to arthropod herbivores was investigated. We distinguished between
two aspects of specificity: specificity of effect (the range of organisms affected by a given induced response), and specificity
of elicitation (ability of the plant to generate distinct chemical responses to different damage types). Specificity of effect
was investigated by examining the effect of restricted feeding by Helicoverpa zea on the resistance of tomato plants to an aphid species ( Macrosiphum euphorbiae), a mite species ( Tetranychus urticae), a noctuid species ( Spodoptera exigua), and to a phytopathogen, Pseudomonas syringae pv. tomato. Prior H. zea feeding was found to increase the resistance of tomato plants to all four organisms. Specificity in elicitation was investigated
by examining the effect of aphid feeding on the activities of four defense-related proteins and on the suitability of foliage
for S. exigua. Aphid feeding was found to induce peroxidase and lipoxygenase activities but not polyphenol oxidase and proteinase inhibitor
activities; this response is distinct from the response to H. zea feeding, which induces polyphenol oxidase and proteinase inhibitors but not peroxidase. Leaflets which had been fed upon
by aphids were better sources of food for S. exigua than were leaflets which had not been fed upon by aphids. Studies of both these aspects of specificity are needed to understand
the way in which plants coordinate and integrate induced responses against insects with other physiological processes.
Received: 20 December 1996 / Accepted: 2 July 1997 相似文献
14.
The strains of Salmonella typhimurium var. Copenhagen isolated from pigeons were characterized by biochemical tests and by phage typing. They were rarely found to cause disease in man. These strains were also rarely found in animals through which they might infect man. It can be concluded that the rôle of pigeons in the spread of salmonellosis in man is small.All strains of phage type 85, and the few strains of phage type 47, biotype 6 were var. Copenhagen. These strains were often found in man. If found in animals, they were practically always isolated from pigs. 相似文献
15.
Terrestrial hermit crabs in the family Coenobitidae (genera Coenobita and Birgus) are distributed in tropical and subtropical regions. They occupy various habitats ranging from shore to inland forests, and the two shore‐dwelling species, Coenobita rugosus and C. violascens, possess different distributional characteristics on Ishigakijima Island, Ryukyu Archipelago, Japan. Coenobita rugosus is distributed throughout the coast of the island and is abundant in beach areas, whereas C. violascens has mainly been found in river mouth areas. However, very little is known about the habitats used by the early life stages of coenobitid crabs because identifying the species of recently landed early juveniles is difficult. We tested whether the species compositions of early juveniles of coenobitids differed between beach and river mouth sites on Ishigakijima Island. We collected and identified the early stage coenobitids using PCR–RFLP techniques. A total of 576 early juveniles of five Coenobita species were collected, of which 0.7% were C. brevimanus, 7.3% were C. cavipes, 0.2% were C. purpureus, 70.1% were C. rugosus, and 21.7% were C. violascens. The early juveniles of Birgus latro were not found. The early juveniles of C. rugosus occurred at both beach and river mouth sites, and they were abundant at beach sites. The early juveniles of C. violascens were only found at river mouth sites. These findings indicate that C. rugosus and C. violascens complete their life cycles on land near the localities where they land. The early juveniles of the inland‐dwelling species, C. cavipes, were also mainly collected from river mouth sites, which suggested that juveniles of C. cavipes selected landing sites near river mouth areas and then migrated into the inland forests, passing through riverside areas. Our results highlighted the importance of river mouth areas for recruitment to adult habitats by some coenobitid species. 相似文献
16.
Nineteen out of 214 strains of microorganisms including moulds, bacteria, actinomycetes and yeasts, which were selected from the culture collection of our laboratory were found to produce the substances which flocculate Saccharomyces cerevisiae AJ4005 (baker’s yeast). Among them are Aspergillus sojae, Anixiella reticulata, Geotrichum candidum, Eupenicillium crustaceus, Circinella sydowi, Monascus anka, Sordaria fimicola, Pseudomonas fluorescens, Staphylococcus aureus, Corynebacterium brevicale, Brevibacterium insectiphilum, Streptomyces vinaceus.The flocculants in the culture broth of these microorganisms precipitated readily by addition of acetone, and flocculated various microorganisms nonspecifically. The flocculant produced by Asp. sojae AJ7002 sedimented activated sludge well. 相似文献
17.
Bile pigments in the bile of the rainbow trout, Salmo gairdneri, tilapia, Tilapia nilotica, and pejerrey, Odonthetes bonariensis, were analyzed by HPLC and TLC.Major bile pigments of rainbow trout and pejerrey were bilirubin glucuronides and ditauro-bilirubin, respectively. Ditaurobilirubin was not detected in rainbow trout and bilirubin glucuronides were scarcely found in pejerrey. Biliverdin seemed to be the sole bile pigment in tilapia, but it was a minor component in the other fish. These results are in accord with the previous reports in which the diversity of bile pigment composition was demonstrated in some fish. 相似文献
18.
Mosquito collections were carried out on microfilaraemic dogs, positive for Dirofilaria sp., for 18 consecutive nights in the coastal town of Celestún, Yucatan, southeast Mexico, during the rainy season (August) of 2007. A total of 292 female mosquitoes representing 12 species of dipteran Culicidae were collected: Anopheles albimanus (Wiedemann); Anopheles crucians (Wiedemann); Anopheles pseudopunctipennis (Theobald); Culex coronator (Dyar & Knab); Culex interrogator (Dyar & Knab); Culex nigripalpus (Theobald); Culex quinquefasciatus (Say); Culex salinarius (Coquillett); Aedes aegypti (Linnaeus); Aedes scapularis (Rondani); Aedes sollicitans (Walker), and Aedes taeniorhynchus (Wiedemann). Aedes taeniorhynchus and Cx. quinquefasciatus were the species found most commonly feeding on the dogs. Filarial nematodes were observed by microscopy in nine of the mosquito species collected; however, third‐instar larvae were only observed in Ae. taeniorhynchus and An. crucians. Of 76 Ae. taeniorhynchus specimens found positive for Dirofilaria sp. by dissection, 14 were confirmed to be positive for Dirofilaria immitis (Leidy) by polymerase chain reaction (PCR). The resulting infection rate for D. immitis confirmed by PCR (6.2%) is higher than any infection rate for Ae. taeniorhynchus previously reported from the Americas. 相似文献
19.
A family of repeated DNA sequences of about 1200 bp in length and bordered by well-conserved, 18 bp inverted repeats ( VfB family) was found in the nuclear genome of Vicia faba. The structure, chromosomal organization, redundancy modulation and evolution of these sequences were investigated. They
are enriched in A+T base pairs (about 40% G+C) and lack any obvious internally repeated motif. A 64%–73% nucleotide sequence
identity was found when pairwise comparisons between VfB sequences were carried out (average 69%). Direct repeats were not found to flank the inverted repeats that border these
DNA sequences. The results obtained by hybridizing VfB repeats to Southern blots of V. faba genomic DNA digested with EcoRI indicated that these DNA elements are interspersed in the genome. The appearance of bands in these Southern blots and comparison
of the structure of the sequences that flank different VfB elements showed that these repeats might be part of other, longer repeated DNA sequences. A high degree of dispersion throughout
the genome was confirmed by cytological hybridization, which showed VfB sequences to be scattered along the length of all chromosomes and to be absent or rare only at heterochromatic chromosomal
regions. These sequences contribute to intraspecific alterations of genomic size. Indeed, dot-blot hybridizations proved that
their redundancy, which is positively correlated with the overall amount of nuclear DNA in each accession, varies between
V. faba land races (27×10 3–230×10 3 copies per 1C DNA). Southern blot hybridization of VfB repeats to restriction endonuclease-digested genomic DNAs of V. faba, V. narbonensis, V. sativa, Phaseolus coccineus, Populus deltoides, and Triticum durum revealed nucleotide sequence homology of these DNA elements, whatever the stringency conditions, only to the DNAs of Vicia species, and to a reduced extent to the DNAs of V. narbonensis and V. sativa compared with that of V. faba. It is concluded that VfB repeats might be descended from mobile DNA elements and contribute to change genomic size and organization during evolution.
Received: 10 September 1998; in revised form: 12 May 1999 / Accepted: 19 May 1999 相似文献
20.
Interactions involving the T-cell receptor (TCR) and major histocompatibility complex (MHC) are fundamental to the generation
of a specific immune response. The study of interpopulation differences in TCR genes may identify those genes which are subject to selection, and also provides useful information for future genetic studies
in these populations. In this study we present analysis of five TCRAV polymorphisms, for V5S1, V6S1, V8S1, V17S1, and V21S1 loci in five human populations by single-strand conformational polymorphism (SSCP) analysis. Caucasian, Chinese, Gambian,
AfroCaribbean, and South American Indians (Mapuches) showed marked interpopulation variation for both the silent ( V5S1, V17S1, and V21S1) and coding ( V6S1 and V8S1) polymorphisms. In general the alleles were conserved in the different populations, but new, additional variants were found
for V5S1 and V17S1 in Gambians and Caucasians. V6S1 overall showed the highest nucleotide diversity, and V6S1 genotype distributions were skewed away from expected values in Chinese and Mapuches. Analysis of allelic associations showed
a general lack of linkage disequilibrium between the loci, which was reflected by the absence of strong population-specific
haplotypes.
Received: 22 April 1997 / Revised: 9 July 1997 相似文献
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