排序方式: 共有101条查询结果,搜索用时 15 毫秒
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Sonia A. Soto‐Rodriguez Rodolfo Lozano‐Olvera Daniel A. Palacios‐Gonzalez Carmen Bolan‐Mejia Karla G. Rendon‐Aguilar 《Journal of the World Aquaculture Society》2019,50(5):1002-1015
The phenotypic characteristics and growth kinetics at several temperatures, salinities, and pH values of three Vibrio parahaemolyticus (Vp) strains with different virulence and one nonpathogenic strain were evaluated. Independent of the virulence of the strain, a high metabolic diversity was found, which yielded different colored phenotypes on the CHROMagar? Vibrio. All strains were resistant to ampicillin and carbenicillin, and Vp AHPND+ organisms were the most sensitive to enrofloxacin. The exponential growth of Vp strains started at 1–2 hr of incubation, although no relationship was observed between the bacterial density and degree of virulence. Moreover, the growth of the most virulent strain was independent of the nutrients in the incubation media during the initial hour postinoculation. No strain grew at 4°C in 0% NaCl and pH 4, but only Vp AHPND+ grew at 44°C. For all strains, the lag phase was proportional to the NaCl concentration, and the growth was better at pH 8–9. However, the Vp AHPND? strain displayed a greater variability, was more sensitive to extreme conditions, and showed a lag phase of 9 hr independent of the pH. 相似文献
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Karla Meza Makoto Inami Alf S. Dalum Ane M. Bjelland Henning Srum Marie Lvoll 《Journal of fish diseases》2019,42(7):1001-1011
Piscirickettsiosis, caused by the intracellular Gram‐negative bacteria Piscirickettsia salmonis, is at present the most devastating disease in the Chilean salmon industry. The aim of this study was to analyse disease development after challenge with a P. salmonis strain (EM90‐like) under a controlled environment by comparing intraperitoneal challenge with cohabitation challenge. The P. salmonis EM90‐like isolate was cultured in a liquid medium for the challenge of 400 Atlantic salmon (Salmo salar) smolts. Cumulative mortality was registered, necropsy was performed, and bacterial distribution in the tissues and histopathological changes were analysed. The results revealed a similar progression of the disease for the two different challenge models. Pathological and histopathological changes became more visible during the development of the clinical phase of the disease. Bacterial DNA was identified in all the analysed tissues indicating a systemic infection. Bacterial tropism to visceral organs was demonstrated by real‐time quantitative PCR and immunohistochemistry. Better knowledge of disease development during P. salmonis infection may contribute to further development of challenge models that mimic the field situation during piscirickettsiosis outbreaks. The models can be used to develop and test future preventive measures against the disease. 相似文献
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Meza JC Sigoillot JC Lomascolo A Navarro D Auria R 《Journal of agricultural and food chemistry》2006,54(11):3852-3858
We propose a new process using a vapor phase bioreactor (VPB) to simultaneously (i) delignify sugar-cane bagasse, a residue of sugar production that can be recycled in paper industry, and (ii) produce laccase, an enzyme usable to bleach paper pulp. Ethanol vapor, used as laccase inducer, was blown up through a VPB packed with bagasse and inoculated with Pycnoporus cinnabarinusss3, a laccase-hyperproducing fungal strain. After 28 days, the laccase activity in the ethanol-treated bagasse was 80-fold higher (80 U g(ds)(-)(1)) and the bagasse delignification percentage was 12-fold (12%) higher than in the reference samples produced in the absence of ethanol, corresponding to a high overall pulp yield of 96.1%. In the presence of ethanol, the total soluble phenols amount was 2.5-fold (3 mg FA g(ds)(-)(1)) higher than that without ethanol. Six monomeric phenols were detected: p-coumaric (4-hydroxyphenyl-2-propenoic), ferulic (4-hydroxy-3-methoxyphenyl-2-propenoic), syringic (4-hydroxy-3,5-dimethoxybenzoic), vanillic (4-hydroxy-3-methoxybenzoic) and 4-hydroxybenzoic acids, and 2-methoxyhydroquinone. Higher concentrations of phenolic compounds were observed when ethanol vapor was added, confirming a more efficient bagasse delignification. After 28 days, the fungal-treated bagasse (with ethanol addition) was pulped and refined. For a freeness of 81 mL CSF, this processing required 50% less energy than with untreated bagasse (without inoculation and ethanol addition), which indicated a significant potential economy for the pulp and paper industry. Handsheets were made from pulp obtained after fungal-treated and untreated bagasse. Comparison of bagasse-pulp characteristics for freeness of 35 and 181 mL CSF showed an average increment by 35% for tensile index and breaking strength and length. VPB allowed a simultaneous production of laccase (90 U g(ds)(-)(1), after pressing of the bagasse) that improved the overall profitability of the process. 相似文献
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We studied the effects of anthropogenic edges on predation and parasitism of forest bird nests in an agriculturally fragmented
landscape and a continuously forested landscape in Ontario, Canada. Nesting data were collected at 1937 nests across 10 species
in the fragmented landscape from 2002–2008, and 464 nests across 4 species in the continuously forested landscape from 2006–2008.
Brood parasitism only occurred in the fragmented landscape, and was positively related to the proportion of rural grassland
and row crop habitats within 500-m of nests. Daily nest survival was negatively related to the density of roads within 500-m
of nests in the fragmented landscape, but was not influenced by distance to anthropogenic edge in either landscape. Predation
rates were higher in the fragmented landscape for Ovenbird and Rose-breasted Grosbeak nests, but did not differ between landscapes
for Veery and American Redstart nests. Uniformly high predation in the fragmented landscape may be a result of (1) matrix
predators that penetrate deep (>300 m) into the forest interior, or (2) the additive effect of forest-dependent and matrix-associated
predators that results in high predation pressure in both edge and interior habitats. Further research focused on the identification
of nest predators, their population dynamics, and habitat use is required to understand the underlying mechanisms leading
to uniformly high nest predation in fragmented landscapes. 相似文献
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Mangale VS Hirokawa KE Satyaki PR Gokulchandran N Chikbire S Subramanian L Shetty AS Martynoga B Paul J Mai MV Li Y Flanagan LA Tole S Monuki ES 《Science (New York, N.Y.)》2008,319(5861):304-309
The earliest step in creating the cerebral cortex is the specification of neuroepithelium to a cortical fate. Using mouse genetic mosaics and timed inactivations, we demonstrated that Lhx2 acts as a classic selector gene and essential intrinsic determinant of cortical identity. Lhx2 selector activity is restricted to an early critical period when stem cells comprise the cortical neuroepithelium, where it acts cell-autonomously to specify cortical identity and suppress alternative fates in a spatially dependent manner. Laterally, Lhx2 null cells adopt antihem identity, whereas medially they become cortical hem cells, which can induce and organize ectopic hippocampal fields. In addition to providing functional evidence for Lhx2 selector activity, these findings show that the cortical hem is a hippocampal organizer. 相似文献
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Positive-strand RNA viruses such as poliovirus replicate their genomes on intracellular membranes of their eukaryotic hosts. Electron microscopy has revealed that purified poliovirus RNA-dependent RNA polymerase forms planar and tubular oligomeric arrays. The structural integrity of these arrays correlates with cooperative RNA binding and RNA elongation and is sensitive to mutations that disrupt intermolecular contacts predicted by the polymerase structure. Membranous vesicles isolated from poliovirus-infected cells contain structures consistent with the presence of two-dimensional polymerase arrays on their surfaces during infection. Therefore, host cytoplasmic membranes may function as physical foundations for two-dimensional polymerase arrays, conferring the advantages of surface catalysis to viral RNA replication. 相似文献
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Primo Anacláudia Alves Araújo Maria Diana Melo Silva Karla da Fonseca Silva Ludmyla Araújo Pereira Graziella de Andrade Carvalho Fernandes Francisco Éden Paiva Pompeu Roberto Cláudio Fernandes Franco Natale William de Souza Henrique Antunes 《Agroforestry Systems》2021,95(8):1459-1464
Agroforestry Systems - The use of native trees in agroecosystems is a promising way to increase litter deposition and nutrient cycling and foster the recovery of degraded areas, especially in... 相似文献
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Ruy B. de Oliveira Filho Karla C. Malta Júnior M.B. Oliveira Vania L. Assis Santana Mabel H.V. Harrop Danilo T. Stipp José W. Pinheiro Júnior 《Journal of Equine Veterinary Science》2014
Leptospirosis is a zoonotic disease that occurs in humans and several animal species, including cattle, pigs, and horses, and it has a worldwide distribution. In equids, leptospirosis manifests through recurrent uveitis and abortion and other reproductive disorders. The objective of the present study was to investigate the epidemiological situation of Leptospira spp. infection in equids from the Brejo Paraibano microregion in the northeast of Brazil, that is, to assess the prevalence of and identify the major risk factors for infection. For this purpose, blood samples were taken from 257 equids (204 horses, 46 mules, and 7 donkeys), and a microscopic agglutination test (MAT) was used as serological analysis, with 24 serovars of Leptospira spp. as antigens. Antibodies were observed in 16.2% of horses, 13.0% of mules, and 28.6% of donkeys. Animals between the ages of 2.5 and 11 years had a risk of infection 0.4 times lower than those younger than 2.5 years old (odds ratio, 0.4; 95% confidence interval, 0.18-0.90). Further studies are needed to identify potential wild reservoirs and the main routes of infections. 相似文献