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Viktoria Michel Claudia Ulber Dietrich Pöhle Beate Köpke Katharina Engel Ute Kaim Ahmad Fawzy Sophie Funk Juliane Fornefett Christoph Georg Baums Tobias Eisenberg 《Antonie van Leeuwenhoek》2018,111(10):1955-1966
Rat bite fever is an under-reported, under-diagnosed emerging zoonosis with worldwide distribution. Besides Spirillum minus, Streptobacillus moniliformis is the major causative microorganism although it usually colonises rats without any clinical signs. A group of house rats (Rattus rattus) kept in a zoo exhibition for educational purposes suffered from neurological signs including disorientation, torticollis, stall walking, ataxia and death. Gross pathological and histo-pathological examinations of the investigated rats revealed high-grade otitis interna et media, from which Streptobacillus notomytis was isolated in pure culture or as the predominant microorganism. This case series underlines a previously expressed hypothesis that R. rattus might be naturally colonised with S. notomytis, whereas the traditional rat bite fever organism, S. moniliformis, might be restricted to the Norway rat (Rattus norvegicus). However, the general paucity of Streptobacillus isolates, especially from their respective animal hosts, precludes definitive proof of these host tropisms. This is the first report of S. notomytis detection outside Asia and Australia and the first evidence for its role as a facultative pathogen in house rats. 相似文献
104.
Adaptive divergence despite strong genetic drift: genomic analysis of the evolutionary mechanisms causing genetic differentiation in the island fox (Urocyon littoralis) 下载免费PDF全文
W. Chris Funk Robert E. Lovich Paul A. Hohenlohe Courtney A. Hofman Scott A. Morrison T. Scott Sillett Cameron K. Ghalambor Jesus E. Maldonado Torben C. Rick Mitch D. Day Nicholas R. Polato Sarah W. Fitzpatrick Timothy J. Coonan Kevin R. Crooks Adam Dillon David K. Garcelon Julie L. King Christina L. Boser Nicholas Gould William F. Andelt 《Molecular ecology》2016,25(10):2176-2194
The evolutionary mechanisms generating the tremendous biodiversity of islands have long fascinated evolutionary biologists. Genetic drift and divergent selection are predicted to be strong on islands and both could drive population divergence and speciation. Alternatively, strong genetic drift may preclude adaptation. We conducted a genomic analysis to test the roles of genetic drift and divergent selection in causing genetic differentiation among populations of the island fox (Urocyon littoralis). This species consists of six subspecies, each of which occupies a different California Channel Island. Analysis of 5293 SNP loci generated using Restriction‐site Associated DNA (RAD) sequencing found support for genetic drift as the dominant evolutionary mechanism driving population divergence among island fox populations. In particular, populations had exceptionally low genetic variation, small Ne (range = 2.1–89.7; median = 19.4), and significant genetic signatures of bottlenecks. Moreover, islands with the lowest genetic variation (and, by inference, the strongest historical genetic drift) were most genetically differentiated from mainland grey foxes, and vice versa, indicating genetic drift drives genome‐wide divergence. Nonetheless, outlier tests identified 3.6–6.6% of loci as high FST outliers, suggesting that despite strong genetic drift, divergent selection contributes to population divergence. Patterns of similarity among populations based on high FST outliers mirrored patterns based on morphology, providing additional evidence that outliers reflect adaptive divergence. Extremely low genetic variation and small Ne in some island fox populations, particularly on San Nicolas Island, suggest that they may be vulnerable to fixation of deleterious alleles, decreased fitness and reduced adaptive potential. 相似文献
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Independent evolutionary histories in allopatric populations of a threatened Caribbean land mammal 下载免费PDF全文
107.
Isoprene emission from plants is one of the principal ways in which plant processes alter atmospheric chemistry. Despite
the importance of this process, few long-term controls over basal emission rates have been identified. Stress-induced changes
in carbon allocation within the entire plant, such as those produced by defoliation, have not been examined as potential mechanisms
that may control isoprene production and emission. Eastern cottonwood (Populus deltoides) saplings were partially defoliated and physiological and growth responses were measured from undamaged and damaged leaves
7 days following damage. Defoliation reduced isoprene emission from undamaged and damaged leaves on partially defoliated plants.
Photosynthetic rates and leaf carbon and nitrogen pools were unaffected by damage. Photosynthetic rate and isoprene emission
were highly correlated in undamaged leaves on undamaged plants and damaged leaves on partially defoliated plants. There was
no correlation between photosynthetic rate and isoprene emission in undamaged leaves on partially defoliated plants. Isoprene
emission was also highly correlated with the number of source leaves on the apical shoot in damage treatments. Increased carbon
export from source leaves in response to defoliation may have depleted the amount of carbon available for isoprene synthesis,
decreasing isoprene emission. These results suggest that while isoprene emission is controlled at the leaf level in undamaged
plants, emission from leaves on damaged plants is controlled by whole-branch allocation patterns.
Received: 12 May 1998 / Accepted: 9 November 1998 相似文献
108.
De Novo Synthesis of 4,5-Dimethoxycatechol and 2,5-Dimethoxyhydroquinone by the Brown Rot Fungus Gloeophyllum trabeum 下载免费PDF全文
Andrzej Paszczynski Ronald Crawford David Funk Barry Goodell 《Applied microbiology》1999,65(2):674-679
The new dimethoxycatechol 4,5-dimethoxy-1,2-benzenediol (DMC) and the new dimethoxyhydroquinone 2,5-dimethoxy-1,4-benzenediol (DMH) were isolated from stationary cultures of the brown rot fungus Gloeophyllum trabeum growing on a glucose mineral medium protected from light. The structure was elucidated by gas chromatography-mass spectrometry through comparison to a synthetic standard. Further confirmation was obtained by forming a dimethoxyoxazole derivative by condensation of DMC with methylene chloride and through examination of methylated derivatives. DMC and DMH may serve as ferric chelators, oxygen-reducing agents, and redox-cycling molecules, which would include functioning as electron transport carriers to Fenton’s reactions. Thus, they appear to be important components of the brown rot decay system of the fungus. 相似文献
109.
Silvana DuranOrtiz Edward O. List Yuji Ikeno Jonathan Young Reetobrata Basu Stephen Bell Todd McHugh Kevin Funk Samuel Mathes Yanrong Qian Prateek Kulkarni Shoshana Yakar Darlene E. Berryman John J. Kopchick 《Aging cell》2021,20(12)
Studies in multiple species indicate that reducing growth hormone (GH) action enhances healthy lifespan. In fact, GH receptor knockout (GHRKO) mice hold the Methuselah prize for the world''s longest‐lived laboratory mouse. We previously demonstrated that GHR ablation starting at puberty (1.5 months), improved insulin sensitivity and female lifespan but results in markedly reduced body size. In this study, we investigated the effects of GHR disruption in mature‐adult mice at 6 months old (6mGHRKO). These mice exhibited GH resistance (reduced IGF‐1 and elevated GH serum levels), increased body adiposity, reduced lean mass, and minimal effects on body length. Importantly, 6mGHRKO males have enhanced insulin sensitivity and reduced neoplasms while females exhibited increased median and maximal lifespan. Furthermore, fasting glucose and oxidative damage was reduced in females compared to males irrespective of Ghr deletion. Overall, disrupted GH action in adult mice resulted in sexual dimorphic effects suggesting that GH reduction at older ages may have gerotherapeutic effects. 相似文献
110.
Uma T. Shankavaram David L. DeWitt Sarah E. Funk E. Helene Sage Larry M. Wahl 《Journal of cellular physiology》1997,173(3):327-334
SPARC (secreted protein, acidic and rich in cysteine), also called osteonectin or BM-40, is a collagen-binding glycoprotein secreted by a variety of cells and is associated with functional responses involving tissue remodeling, cell movement and proliferation. Because SPARC and monocytes/macrophages are prevalent at sites of inflammation and remodeling in which there is connective tissue turnover, we examined the effect of SPARC on monocyte matrix metalloproteinase (MMP) production. Treatment of human peripheral blood monocytes with SPARC stimulated the production of gelatinase B (MMP-9) and interstitial collagenase (MMP-1). Experiments with synthetic peptides indicated that peptide 3.2, belonging to the alpha helical domain III of SPARC, is the major peptide mediating the MMP production by monocytes. SPARC and peptide 3.2 were also shown to induce prostaglandin synthase (PGHS)-2 as determined by Western and Northern blot analyses. The increase in PGHS-2 stimulated by SPARC or peptide 3.2 correlated with substantially elevated levels of prostaglandin E2 (PGE2) and other arachidonic acid metabolites as measured by radioimmunoassay and high performance liquid chromatography (HPLC), respectively. Moreover, the synthesis of MMP was dependent on the generation of PGE2 by PGHS-2, since indomethacin inhibited the production of these enzymes and their synthesis was restored by addition of exogenous PGE2 or dibutyryl cAMP (Bt2cAMP). These results demonstrate that SPARC might play a significant role in the modulation of connective tissue turnover due to its stimulation of PGHS-2 and the subsequent release of PGE2, a pathway that leads to the production of MMP by monocytes. J. Cell. Physiol. 173:327–334, 1997. Published 1997 Wiley-Liss, Inc. 1 This article was prepared by a group of United States government employees and non-United States government employees, and as such is subject to 17 U.S.C. Sec. 105. 相似文献