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941.
María Teresa Tejedor-Junco Margarita González-Martín Estefanía Bermeo-Garrido Rebeca Villasana-Loaiza Elena Carretón-Gómez 《Veterinary research communications》2018,42(3):227-232
Doxycycline is an antibiotic that, in addition to the classic antibacterial use, is also prescribed to fight parasitic diseases, like heartworm disease in dogs. Despite the concern that the overuse of this antibiotic may decrease susceptibility of clinically important bacteria, the consequences of the prolonged doxycycline therapy in heartworm-infected dogs have never been studied before. We have analyzed the impact of this therapy on Staphylococcus aureus and Enterococcus antimicrobial resistance. In this study, 17 heartworm-infected dogs (10 that had completed the doxycycline treatment and 7 dogs that had not yet begun) were included. Twenty-four isolates of Staphylococcus aureus were obtained from two locations of each dog. After treatment, 73.3% of isolates were resistant to at least one antibiotic but only 22.2% of isolates before treatment. Most of doxycycline resistant isolates were obtained from dogs that have received treatment. Erythromycin resistance or intermediate susceptibility was detected in 45.6% of isolates, most of them from dogs after treatment. For Enterococci, 48 isolates were obtained from fecal samples (25 before treatment and 23 after treatment). Before treatment, 32% of isolates were resistant at least to one antibiotic while after, this data increase up to 65%. Comparing isolates before and after treatment, a clear increase in resistance to doxycycline (12% against 21.74%) and erythromycin (20% against 39.13%) was observed. Although the present work is a preliminary research, the results encourages the development of further studies to determinate the effect of prolonged doxycycline therapy on antimicrobial resistance. 相似文献
942.
943.
Ruminant livestock depends primarily on forage and grazing resources from both natural pastures and from cultivated land. Low‐input large‐scale grazing systems constitute a substantial part of what is termed High Nature Value farmland in Europe. Developing a typology of categories of livestock systems within a region is an important step in understanding land uses that involve ruminant livestock systems and their use of feed resources, and in appraising policy options. This study developed a typology based on the municipalities of the region of Aragon in the north‐east of Spain on the basis of the feed resources for ruminant livestock. A clustering analysis was applied to the following three types of criteria: (i) crop types; (ii) vegetation types of uncultivated land and (iii) stocking rate of dairy cattle, beef cattle, sheep and goats. A total of thirty‐nine variables were used. The cluster methodology allowed relatively homogeneous groups of municipalities, termed territories, with differentiating characteristics to be obtained. A Geographic Information System was applied to locate spatially the territories. From the twelve territories identified, it was concluded that there was a low use of natural pastures and high use of resources of cultivated origin in livestock systems in Aragon. 相似文献
944.
Guillermo J. Martínez Pastur Pablo L. Peri Juan M. Cellini María V. Lencinas Marcelo Barrera Horacio Ivancich 《Annals of Forest Science》2011,68(3):587-594
•Introduction
Silviculture systems applied in Nothofagus pumilio forests are based on opening the canopy to stimulate natural regeneration by modifying light and soil moisture. The objective is to evaluate regeneration dynamics of N. pumilio along different forest canopy and solar radiation gradients. 相似文献945.
Serge MORAND Frédéric BORDES Hsuan‐Wien CHEN Julien CLAUDE Jean‐François COSSON Maxime GALAN Gábor Á CZIRJÁK Alex D GREENWOOD Alice LATINNE Johan MICHAUX Alexis RIBAS 《Integrative zoology》2015,10(5):409-423
We summarize the current knowledge on parasitism‐related invasion processes of the globally invasive Rattus lineages, originating from Asia, and how these invasions have impacted the local epidemiology of rodent‐borne diseases. Parasites play an important role in the invasion processes and successes of their hosts through multiple biological mechanisms such as “parasite release,” “immunocompetence advantage,” “biotic resistance” and “novel weapon.” Parasites may also greatly increase the impact of invasions by spillover of parasites and other pathogens, introduced with invasive hosts, into new hosts, potentially leading to novel emerging diseases. Another potential impact is the ability of the invader to amplify local parasites by spillback. In both cases, local fauna and humans may be exposed to new health risks, which may decrease biodiversity and potentially cause increases in human morbidity and mortality. Here we review the current knowledge on these processes and propose some research priorities. 相似文献
946.
Uniform chitosan fibers (CS/PEO) with diameter of 398±76 nm were prepared by electrospinning with merely 5 wt.% of poly(ethylene oxide) (PEO) loading, and then annealed at elevated temperature without the use of additional crosslinker to improve the thermostability and solvent resistance. Swelling test shows that the CS/PEO composite fibers annealed at 200 oC were stable in 50 wt.% acetic acid aqueous solution. The mechanical strength test shows that the annealing temperature can affect the tensile strength of CS/PEO composite fiber mat. The cross-linked CS/PEO composite fibers provide a useful platform for the immobilization of palladium catalyst to catalyze the Mizoroki-Heck reactions of aromatic halides with olefins. Moreover, these CS/PEO composite fibers could be post modified with special ligands to chelate palladium species efficiently to further improve the catalytic activity and stability. 相似文献
947.
948.
Jorge Durán Alexandra Rodríguez José María Fernández-Palacios Antonio Gallardo 《Biology and Fertility of Soils》2009,45(7):781-788
The concern that climate change may increase fire frequency and intensity has recently heightened the interest in the effects
of wildfires on ecosystem functioning. Although short-term fire effects on forest soils are well known, less information can
be found on the long-term effects of wildfires on soil fertility. Our objective was to study the 17-year effect of wildfires
on forest net mineralization rates and extractable inorganic nitrogen (N) and phosphorus (P) concentrations. We hypothesize
that (1) burned forest stands should exhibit lower net mineralization rates than unburned ones; (2) these differences would
be greatest during the growing season; (3) differences between soil variables might also be observed among plots from different
years since the last fire; and (4) due to fire-resistant geochemical processes controlling P availability, this nutrient should
recover faster than N. We used a wildfire chronosequence of natural and unmanaged Pinus canariensis forests in La Palma Island (Canary Islands). Soil samples were collected during winter and spring at 22 burned and unburned
plots. We found significantly higher values for net N mineralization and extractable N pools in unburned plots. These differences
were higher for the winter sampling date than for the spring sampling date. Unlike extractable N and N mineralization rates,
extractable P levels of burned plots exhibited a gradual recovery over time after an initial decrease. These results demonstrate
that P. canariensis forest soils showed low resilience after wildfires, especially for N, and that this disturbance might induce long-term changes
in ecosystem functioning. 相似文献
949.
María D. Ayala Juan M. Martínez Jorge Hernández-Urcera Rosa Cal 《Fish physiology and biochemistry》2016,42(3):1027-1042
Turbot specimens were kept at three temperatures (T s ): warm (W) (21–22 °C), ambient (A) (17–18 °C) and cold (C) (13–14 °C) during the larval and early postlarval stages. At 90 days posthatching (dph), all of them were transferred to ambient T until 190 dph. At 2–3 dph, the specimens showed a monolayer of red muscle and immature white fibres; external or dermomyotome cells (presumptive myogenic cells) were observed on the surface of the red muscle. In the following stages, many myogenic cells and presumptive myogenic precursors were observed within the myotome, presumably derived of the dermomyotome. When comparing the growth at the same age (2, 10, 25, 37 dph), the body length and the muscle growth were positively influenced by the warm T, being the hyperplasia the muscle parameter more significantly influenced. The development rate was also positively correlated with the high T: the beginning of the metamorphosis took place at 15, 23 and 25 dph at W, A and C temperatures, respectively, with the highest body length values at ambient temperature. The metamorphosis finished at 25, 30 and 37 dph at W, A and C temperatures, respectively, with the highest body length values at warm temperature. However, the muscle cellularity was similar in all the groups at the end of the metamorphosis. At 90 and 190 dph, the largest body length was observed at W temperature. However, the muscle cellularity was similar between A and W; the number of fibres was similar in all the groups at 190 dph, which shows the beginning of a compensatory muscle growth in A and C, mainly in A. 相似文献
950.
Marília Hauser Carolina R.C. Doria Roberto V. Santos Aurea García‐Vasquez Marc Pouilly Christophe Pcheyran Emmanuel Ponzevera Gislene Torrente‐Vilara Sylvain Brail Jacques Panfili Audrey Darnaude Jean‐Franois Renno Carmen García‐Dvila Jesus Nuez Franck Ferraton Gladys Vargas Fabrice Duponchelle 《水产资源保护:海洋与淡水生态系统》2019,29(3):397-408