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1.
Three-week-old weaned and colostrum-deprived neonatal (less than 1 day old) pigs were inoculated to determine the pathogenicity of 2 enterotoxigenic Escherichia coli isolates that do not express K88, K99, F41, or 987P adhesins (strains 2134 and 2171). Strains 2134 and 2171 were isolated from pigs that had diarrhea after weaning attributable to enterotoxigenic E coli infection. We found that both strains of E coli adhered in the ileum and caused diarrhea in pigs of both age groups. In control experiments, adherent bacteria were not seen in the ileum of pigs less than 1 day old or 3 weeks old that were noninoculated or inoculated with a nonpathogenic strain of E coli. These control pigs did not develop diarrhea. Antisera raised against strains 2134 and 2171 and absorbed with the autologous strain, grown at 18 C, were used for bacterial-agglutination and colony-immunoblot assays. Both absorbed antisera reacted with strains 2134 and 2171, but not with strains that express K99, F41, or 987P adhesins. A cross-reaction was observed with 2 wild-type K88 strains, but not with a K12 strain that expresses K88 pili. Indirect immunofluorescence with these absorbed antisera revealed adherent bacteria in frozen sections of ileum from pigs infected with either strain. We concluded that these strains are pathogenic and express a common surface antigen that may be a novel adhesin in E coli strains that cause diarrhea in weaned pigs. 相似文献
2.
K. Jung Y. Ha S.‐K. Ha D. U. Han D.‐W. Kim W. K. Moon C. Chae 《Zoonoses and public health》2004,51(2):72-76
The aim of these experiments was to investigate the potential antiviral effect of Saccharomyces cerevisiaeβ‐glucan on the pneumonia induced by swine influenza virus (SIV). Forty colostrum‐deprived 5‐day‐old piglets were randomly divided into four groups of 10. The 20 pigs in groups 1 and 2 were administered Saccharomyces cerevisiaeβ‐glucan orally (50 mg/day/pig; En‐Bio Technology Co., Ltd) for 3 days before SIV infection and those in groups 3 and 4 were given culture medium/diluent alone. Groups 1 and 3 were inoculated intranasally with 3 ml of tissue culture fluid containing 2 × 106 tissue culture infective doses 50% (TCID50)/ml of SIV and those in groups 2 and 4 were exposed in the same manner to uninfected cell culture supernatant. The microscopic lung lesions induced by SIV infection (group 1 pigs) were significantly more severe than those induced by infection in animals pre‐administered β‐glucan (group 3) (P < 0.05). Significantly more SIV nucleic acid was detected in the lungs of pigs experimentally infected with SIV only (group 1) at 5, 7 and 10 days post‐inoculation (dpi) compared with lungs from pigs pre‐administered β‐glucan and infected with SIV (group 3) (P < 0.05). The concentrations of interferon‐γ (IFN‐γ) and nitric oxide (NO) in bronchoalveolar lavage fluid from pigs pre‐administered β‐glucan and infected with SIV (group 3) were significantly higher than for any other group at 7 and 10 dpi for IFN‐γ, and at 5, 7 and 10 dpi for NO (P < 0.05). Saccharomyces cerevisiaeβ‐glucan reduced the pulmonary lesion score and viral replication rate in SIV‐infected pigs. These findings support the potential application of β‐glucan as prophylactic/treatment agent in influenza virus infection. 相似文献
3.
It has been widely hypothesized that a warmer climate in Greenland would increase the volume of lubricating surface meltwater reaching the ice-bedrock interface, accelerating ice flow and increasing mass loss. We have assembled a data set that provides a synoptic-scale view, spanning ice-sheet to outlet-glacier flow, with which to evaluate this hypothesis. On the ice sheet, these data reveal summer speedups (50 to 100%) consistent with, but somewhat larger than, earlier observations. The relative speedup of outlet glaciers, however, is far smaller (<15%). Furthermore, the dominant seasonal influence on Jakobshavn Isbrae's flow is the calving front's annual advance and retreat. With other effects producing outlet-glacier speedups an order of magnitude larger, seasonal melt's influence on ice flow is likely confined to those regions dominated by ice-sheet flow. 相似文献
4.
5.
Lee KH Cho JY Lee HJ Ma YK Kwon J Park SH Lee SH Cho JA Kim WS Park KH Moon JH 《Journal of agricultural and food chemistry》2011,59(18):10124-10128
Two novel caffeoylmalic acid methyl esters, 2-O-(trans-caffeoyl)malic acid 1-methyl ester (6) and 2-O-(trans-caffeoyl)malic acid 4-methyl ester (7), were isolated from pear (Pyrus pyrifolia Nakai cv. Chuhwangbae) fruit peels. In addition, 5 known hydroxycinnamoylmalic acids and their methyl esters were identified: 2-O-(trans-coumaroyl)malic acid (1), 2-O-(cis-coumaroyl)malic acid (2), 2-O-(cis-coumaroyl)malic acid 1-methyl ester (3), 2-O-(trans-coumaroyl)malic acid 1-methyl ester (4), and 2-O-(trans-caffeoyl)malic acid (phaselic acid, 5). The chemical structures of these compounds were determined by spectroscopic data from ESI MS and NMR. Of all the isolated compounds, five hydroxycinnamoylmalic acids and their methyl esters (2-4, 6, 7) were identified in the pear for the first time. 相似文献
6.
Identification of a RAPD marker linked to a brown planthopper resistance gene in rice 总被引:12,自引:0,他引:12
We report the tagging of a brown planthopper (BPH) resistance gene (Bph–1) in rice using RAPD and RFLP markers. The Korean
rice variety ‘Gayabyeo’ has dominant duplicate genes including Bph–1 conferring resistance to biotype 1 of BPH. Bulked segregant
RAPD analysis was employed for rapid identification of DNA markers linked to resistance genes. For tagging these two genes,
an F2F3 population from a ‘Gayabyeo’ × ‘Nagdongbyeo’ cross was developed and evaluated for BPH resistance. Three bulked DNAs
from two groups of homozygous BPH resistant (each for Bph–1 and the other unknown gene) and homozygous susceptible F2 plants
were analyzed by RAPD using 140 random oligomers. One primer, OPD–7 yielded a 700-bp fragment that was present in Gayabyeo
and resistant F2 plants (homozygous for Bph-1 locus) but absent in Nagdongbyeo and susceptible F2 plants. Cosegregation of
this marker with Bph-1 was verified using an F2 population segregating for Bph-1. Chromosomal regions surrounding the Bph-1
were examined with additional RFLP and microsatellite markers on chromosome 12 to define the location of the RAPD marker and
Bph-1. Use of this RAPD marker could facilitate early selection of resistant lines for BPH.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
7.
Dennis N. Lozada R. Esten Mason Md Ali Babar Brett F. Carver Gina-Brown Guedira Keith Merrill Maria Nelly Arguello Andrea Acuna Lucas Vieira Amanda Holder Christopher Addison David E. Moon Randal G. Miller Susanne Dreisigacker 《Euphytica》2017,213(9):222
Genome-wide association studies (GWAS) are useful to facilitate crop improvement via enhanced knowledge of marker-trait associations (MTA). A GWAS for grain yield (GY), yield components, and agronomic traits was conducted using a diverse panel of 239 soft red winter wheat (Triticum aestivum) genotypes evaluated across two growing seasons and eight site-years. Analysis of variance showed significant environment, genotype, and genotype-by-environment effects for GY and yield components. Narrow sense heritability of GY (h 2 = 0.48) was moderate compared to other traits including plant height (h 2 = 0.81) and kernel weight (h 2 = 0.77). There were 112 significant MTA (p < 0.0005) detected for eight measured traits using compressed mixed linear models and 5715 single nucleotide polymorphism markers. MTA for GY and agronomic traits coincided with previously reported QTL for winter and spring wheat. Highly significant MTA for GY showed an overall negative allelic effect for the minor allele, indicating selection against these alleles by breeders. Markers associated with multiple traits observed on chromosomes 1A, 2D, 3B, and 4B with positive minor effects serve as potential targets for marker assisted breeding to select for improvement of GY and related traits. Following marker validation, these multi-trait loci have the potential to be utilized for MAS to improve GY and adaptation of soft red winter wheat. 相似文献
8.
Previous studies have reported very low rates of gluconeogenesis from lactate in sea raven (Hemitripterus americanus) hepatocytes compared to other teleosts studied. This study examines whether hepatic cell redox or lactate dehydrogenase
(LDH) characteristics may explain this observation. Sea raven hepatic optimal LDH activities (pyruvate reductase direction)
were more than 40 times less compared with rainbow trout liver values (40 vs 1914 μmol·min−1·g−1 protein). The Km(lactate) was 9.24 and 0.86 mM for sea raven and trout hepatic LDH, but the Km(pyruvate) was similar between
the two species (0.11 and 0.21 mM, respectively). These results suggested that sea raven liver LDH did not favour lactate
use and was more indicative of the mammalian M-isozyme. Gel electrophoresis showed a predominant intermediate isozyme, with
a small amount of the M-type LDH. Phosphoenolpyruvate carboxykinase (PEPCK) was localized to the mitochondrial compartment,
while there was no apparent mitochondrial glutamate-oxaloacetate transaminase (GOT) activity. No in vitro lactate flux to glucose was found in untreated, 10 mM ethanol-treated, or 3 mM NH4Cl-treated sea raven hepatocytes, although CO2 production from lactate was decreased by ethanol and increased by NH4Cl. These results provide evidence that cell redox does not limit gluconeogenesis from lactate, while low activities and the
kinetic characteristics of LDH may partially explain the low lactate gluconeogenesis reported in sea raven hepatocytes.
To whom correspondence should be addressed at University of Ottawa. 相似文献
9.
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