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1.
Culture filtrates of virulent Nocardia asteroides GUH-2 after growth in acetate minimal medium displayed an absorbance maximum at 320 nm. After isolation by polyamide extraction and anion chromatography, a UV-active compound with this absorbance was shown to be 2,3-dihydroxybenzoic acid (DHB) by nuclear magnetic resonance, gas chromatographic, and mass spectrometric techniques. DHB production under several culture conditions was quantified by a standard high-pressure liquid chromatography assay. Under iron deficiency conditions, N. asteroides GUH-2 excreted up to 11 mg of DHB per liter into the culture medium. No DHB was detected when N. asteroides GUH-2 was grown in an iron-rich medium. With the less virulent strain N. asteroides 10905, DHB was not found under any condition tested.  相似文献   
2.
Metabolic profiling by capillary liquid chromatography-electrospray mass spectrometry was used to monitor shifts in the proferrioxamine profiles of Erwinia amylovora in response to externally supplied potential proferrioxamine precursors, selected stable-isotope-labeled precursors and atypical precursors. Based on the qualitative and quantitative shifts in the proferrioxamine profiles, lysine and arginine are unambiguous, and agmatine, ornithine, diaminobutyric acid and the corresponding C3–5 diamines are highly likely precursors for proferrioxamine biosynthesis in E. amylovora. 5-Hydroxylysine (Hyl), a recently discovered growth inhibitor for E. amylovora, suppresses proferrioxamine production. The Hyl-induced growth inhibition can be reversed by basic amino acids. The basic amino acids also partly restore proferrioxamine synthesis.Part 12 in the series Metabolites of Erwinia, for Parts 10 and 11 see Feistner (1994d) and Feistner (1995b), respectively. Presented, in part, at ALEX '93. San Francisco. October 5–7. 1993, and at the 42nd ASMS Conference. Chicago. May 29–June 3, 1994.  相似文献   
3.
The use of floor-covering has been shown to substantially alter the behavior of captive terrestrial primates. Experiments with two large family groups of common marmosets (Callithrix jacchus) and two of cotton-top tamarins (Saguinus oedipus) have shown that the type of floor-covering also beneficially alters the behavior of arboreal monkeys, increasing use of the floor and decreasing inactivity. These effects increased over 2.5 mo, and appeared to be due to the reduced aversiveness of the floor. Hanging screens also produced beneficial effects.  相似文献   
4.
    
The quantitative and qualitative changes in the contents of foliar secretory cavities during development of Tagetes erecta CV. Moonshot plants were determined. Separation of the secretory components by HPLC yielded three major compounds, subsequently identified by mass spectroscopy, UV spectra, and cochromatography as indole, piperitenone, and piperitone. Comparison of extracts from isolated cavities vs. lamina without cavities showed that in all cases the components were absent from lamina tissues. The quantities of indole and piperitone, in general, increased as the plants developed up to the stage of early flowering, when there was a reduction in total content. At late flowering, the amounts of these components, once again, increased. Concomitantly, the amount of piperitenone decreased during plant development. At all ages studied, indole comprised at least 99% of the total secretion product. This is the first report of the secretory components being restricted to the cavities.  相似文献   
5.
Pneumoviruses have been identified as causative agents in several respiratory disease outbreaks in habituated wild great apes. Based on phylogenetic evidence, transmission from humans is likely. However, the pathogens have never been detected in the local human population prior to or at the same time as an outbreak. Here, we report the first simultaneous detection of a human respiratory syncytial virus (HRSV) infection in western lowland gorillas (Gorilla gorilla gorilla) and in the local human population at a field program in the Central African Republic. A total of 15 gorilla and 15 human fecal samples and 80 human throat swabs were tested for HRSV, human metapneumovirus, and other respiratory viruses. We were able to obtain identical sequences for HRSV A from four gorillas and four humans. In contrast, we did not detect HRSV or any other classic human respiratory virus in gorilla fecal samples in two other outbreaks in the same field program. Enterovirus sequences were detected but the implication of these viruses in the etiology of these outbreaks remains speculative. Our findings of HRSV in wild but human-habituated gorillas underline, once again, the risk of interspecies transmission from humans to endangered great apes.  相似文献   
6.
Proferrorosamine A (pFR A) of the plant pathogenic bacterium Erwinia rhapontici was shown to inhibit growth of wheat and cress seedlings at the 10 ppm level. When the seeds were continuously exposed to 100 ppm pFR A, the germination of cress and wheat seeds was inhibited up to 90% and 80%, respectively. The inhibition could be reversed through addition of equimolar amounts of ferrous iron, which indicates that the strong iron chelating capability of pFR A is responsible for the observed effect. The Fe(II) in the corresponding iron complex, ferrorosamine A, was found to be remarkably resistant towards oxidation by hydrogen peroxide and therefore redox-cycling in the Haber-Weiss cycle. It is thus conceivable that pFR A may also attenuate the generation of reactive hydroxyl radicals during the resistant and wound reaction. The apparent correlation between proferrorosamine production and virulence in erwiniae was further corroborated through the analysis of Erwinia persicinus, a newly described species. Using electrospray ionization mass spectrometry, E. persicinus was shown to produce pFR A and pFR B, and preliminary evidence for the phytopathogenicity of E. persicinus was found in cress. Inhibition of wheat seedlings by E. persicinus could not be demonstrated, but this may be due to technical difficulties or different host specificities. Taken together, our results indicate that the phytopathogenicity of E. rhapontici and E. persicinus may, as least in part, be due to the release of proferrorosamines.  相似文献   
7.
Mandrills, Mandrillus sphinx, colorful terrestrial primates from the tropical forests of West Central Africa, are poorly known in the wild. The formation at the International Medical Research Center of Franceville, Gabon, of a semifreeranging, cohesive, reproducing group of mandrills in a highly naturalistic setting provided a unique resource for the study of this threatened species. The acquisition and release of 15 mandrills into a 1.4 ha and then a 5.3 ha enclosure of natural gallery forest is described. Thirty-three births in the group resulted in 23 surviving offspring over a period of six years. Apparent early reproduction in females was indicated by small size at conception, presence of several deciduous teeth at the time of first parturition, continued weight gain through subsequent births, and decreasing inter-birth intervals. © 1992 Wiley-Liss, Inc.  相似文献   
8.
Isolation and characterization of a Drosophila neuropeptide gene   总被引:5,自引:0,他引:5  
We have purified a 9 amino acid amidated neuropeptide, DPKQDFMRFamide, from whole adult D. melanogaster. This peptide exhibits sequence homology to the molluscan bioactive tetrapeptide FMRFamide and is a novel member of the FMRFamide peptide family. The gene encoding DPKQDFMRFamide has been cloned and characterized. It is present in a single copy per haploid genome, is expressed as a unique 1.7 kb mRNA species, and cytologically maps to 46C on the right arm of chromosome 2. Characterization of a cDNA clone indicates that the precursor protein is 347 amino acids in length and contains 5 copies of DPKQDFMRFamide, as well as 10 additional amidated peptides exhibiting varying degrees of structural relatedness. The Drosophila DPKQDFMRFamide gene and the Aplysia FMRFamide gene are ancestrally related; however, peptides display a higher degree of homology within a species than between species, suggesting intragenic concerted evolution of these neuropeptides.  相似文献   
9.
Despite early menageries being the source of much useful biological information on anatomy and taxonomy, it is only more recently that the potential for research in zoos has been recongnized. Collections of captive animals are unique and irreplaceable resources for conservation; but without research in zoological parks, progress in conservation science would diminish. There is a flow of information from zoo researchers to field scientists that assists in providing new insights into species biology. Reciprocally, data collected in the field enhance efforts in captive breeding. This paper summarizes the new research initiatives undertaken in zoos, e.g., in the fields of reproductive and genetic technologies, and highlights their significance for conservation and management of threatened species. It is evident that zoo research has a vital role in linking in situ and ex situ conservation. This role needs to be expanded and developed to meet the challenge posed by expanding human and declining wildlife populations and ecosystems.  相似文献   
10.
We investigated food sharing behavior in 5 litters of pied bare-faced tamarins (Saguinus bicolor bicolor)—8 infants, from 3 families—from 5 to 26 weeks of age. The frequency of sharing by parents in response to infant begging increased steadily from the age of 5 weeks to 16 weeks, and then declined. Offering of food by adults without prior infant begging occurred at very low frequencies throughout observations (1.5% of total items transferred). On average, infants received approximately equal amounts of food from transfers from others and by self feeding until about 20 weeks, after which self feeding began to predominate. Begging success—the proportion of infant begs which resulted in food sharing—remained relatively constant over time, at 60–70%. Overall, therefore, the frequency of food sharing seemed to be governed by changes in infant rather than adult behavior. There were individual differences between adults in their response to infant begging, but two of three fathers transferred significantly more food to infants than mothers did. The results of this study emphasize the existence of specific and individual differences in food-sharing behavior, which must be taken into account in explaining its importance in the reproductive strategies of the Callitrichidae.  相似文献   
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