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21.
M Ozkan SG Desai Y Zhang DM Stevenson J Beane EA White ML Guerinot LR Lynd 《Journal of industrial microbiology & biotechnology》2001,27(5):275-280
Characteristics of 13 newly isolated thermophilic, anaerobic, and cellulolytic strains were compared with previously described
strains of Clostridium thermocellum: ATCC 27405 and JW20 (ATCC 31549). Colony morphology, antibiotic sensitivity, fermentation end-products, and cellulose degradation
were documented. All 13 strains were sensitive to erythromycin (5 μg/ml) and chloramphenicol (25 μg/ml), and all strains but
one were sensitive to kanamycin (20 μg/ml). Polymerase chain reaction (PCR) amplification using primers based on gene sequences
from C. thermocellum ATCC 27405 was successful for all 13 strains in the case of the hydrogenase gene and 11 strains in the case of phosphotransacetylase/acetate
kinase genes. Ten strains amplified a product of the expected size with primers developed to be specific for C. thermocellum 16SrRNA primers. Two of the 13 strains did not amplify any product with the PCR primers designed for the phosphotransacetylase/acetate
kinase and 16SrRNA primers. A MboI-like GATC- recognizing restriction activity was present in all of the five strains examined. The results of this study have
several positive implications with respect to future development of a transformation system for cellulolytic thermophiles.
Journal of Industrial Microbiology & Biotechnology (2001) 27, 275–280.
Received 12 September 2000/ Accepted in revised form 20 November 2000 相似文献
22.
The use and practicability of microwave-assisted staining procedures in routine histopathology has been well established for more than 17 years. In the study reported here, we aimed to examine an alternative approach that would shorten the duration of dewaxing and clearing steps of hematoxylin and eosin (H & E) staining of paraffin sections by using a microwave oven. Although xylene is one of the most popular dewaxing and clearing agents, its flammability restricts its use in a microwave oven; thus we preferred 1,1,1 trichloroethane, which is not flammable, as the dewaxing and clearing agent in the present study. In Group I and Group II (control groups), intestine was processed with xylene and 1,1,1 trichloroethane, respectively. The sections were then stained with H & E according to the conventional staining protocol at room temperature and subdivided into two groups according to the duration of dewaxing and clearing in xylene. In Groups III and IV (experimental groups) similar tissues were processed with xylene and 1,1,1 trichloroethane, respectively; however, sections from these groups were divided into four subgroups to study the period required for dewaxing and clearing in 1,1,1 trichloroethane, then stained with H & E in the microwave oven at 360 W for 30 sec. Our conventional H & E staining procedure, which includes dewaxing, staining and clearing of sections, requires approximately 90 min, while our method using 1,1,1 trichloroethane and microwave heating required only 2 min. Our alternative method for H & E staining not only reduced the procedure time significantly, but also yielded staining quality equal or superior to those stained the conventional way. Our results suggest that 1,1,1 trichloroethane can be used effectively and safely as a dewaxing and clearing agent for H & E staining in a microwave oven. 相似文献
23.
Evolutionary rates for tuf genes in endosymbionts of aphids 总被引:5,自引:1,他引:4
The gene encoding elongation factor Tu (tuf) in aphid endosymbionts (genus
Buchnera) evolves at rates of 1.3 x 10(-10) to 2.5 x 10(-10) nonsynonymous
substitutions and 3.9 x 10(-9) to 8.0 x 10(-9) synonymous substitutions per
position per year. These rates, which are at present among the most
reliable substitution rates for protein-coding genes of bacteria, have been
obtained by calibrating the nodes in the phylogenetic tree produced from
the Buchnera EF-Tu sequences using divergence times for the corresponding
ancestral aphid hosts. We also present data suggesting that the rates of
nonsynonymous substitutions are significantly higher in the endosymbiont
lineages than in the closely related free-living bacteria Escherichia coli
and Salmonella typhimurium. Synonymous substitution rates for Buchnera
approximate estimated mutation rates for E. coli and S. typhimurium, as
expected if synonymous changes act as neutral mutations in Buchnera. We
relate the observed differences in substitution frequencies to the absence
of selective codon preferences in Buchnera and to the influence of Muller's
ratchet on small asexual populations.
相似文献
24.
Dabek M Podgurniak P Piedra JL Szymańczyk S Filip R Wojtasz-Pajak A Werpachowska E Podgurniak M Pierzynowski SG 《Bioelectromagnetics》2007,28(4):275-280
Gut enzymes in the small intestine are exposed to extremely low electrical currents (ELEC) generated by the smooth muscle. In the present study, the in vitro tests were undertaken to evaluate the effect of these electric currents on the activity of the proteolytic pancreatic digestive enzymes. A simulator generating the typical electrical activity of pig gut was used for these studies. The electric current emitted by the simulator was transmitted to the samples, containing enzyme and its substrate, using platinum plate electrodes. All samples were incubated at 37 degrees C for 1 h. The changes in optical density, corresponding to enzyme activity, in samples stimulated for 1 h with ELEC was compared with that not exposed to ELEC. The obtained results show that the electrical current with the characteristics of the myoelectrical migrating complex (MMC) has an influence on pancreatic enzyme activity. Increased endopeptidase and reduced exopeptidase activity was noticed in samples treated with ELEC. This observation can be of important as analyzed factors which can alter enzymatic activity of the gut, can thus also affect feed/food digestibility. 相似文献
25.
Ghrelin is a multifunctional peptide produced predominantly in the stomach, however substantial amounts have also been found in colostrum and milk. The aim of the study was to investigate the effect of exogenous ghrelin, administered intra-gastrically, on the processes of mitosis, apoptosis, autophagy, crypt fission and changes in histometry of the small intestine mucosa in neonatal pigs, fed with a milk formula. Three groups (n=6) of piglets were used in the study. The pigs were fed either milk formula (C7) or milk formula together with ghrelin, administered via a stomach tube (7.5 μg/kg body weight (BW), (LG)) and 15 μg/kg BW (HG), every 8h for 6 days. Compared to the control group (C7), feeding milk formula supplemented with ghrelin resulted in significant changes in the small intestinal morphometry and mucosa histometry. The observed changes were dependent on the dosage of hormone and the part of intestine investigated. Administration of ghrelin via the stomach tube (HG) significantly influenced epithelial cell renewal. Moreover, we demonstrated that autophagy is involved in the small intestine mucosa remodeling and ghrelin may be an important factor for its regulation. In conclusion, we found that enteral ghrelin influences the gut mucosa remodeling in a dose-related manner in the early postnatal period. Moreover in neonates, stomach activity does not interfere with the action of ghrelin in the small intestine. 相似文献
26.
27.
Paulo C Carvalho Juliana SG Fischer Emily I Chen John R YatesIII Valmir C Barbosa 《BMC bioinformatics》2008,9(1):316
Background
A goal of proteomics is to distinguish between states of a biological system by identifying protein expression differences. Liu et al. demonstrated a method to perform semi-relative protein quantitation in shotgun proteomics data by correlating the number of tandem mass spectra obtained for each protein, or "spectral count", with its abundance in a mixture; however, two issues have remained open: how to normalize spectral counting data and how to efficiently pinpoint differences between profiles. Moreover, Chen et al. recently showed how to increase the number of identified proteins in shotgun proteomics by analyzing samples with different MS-compatible detergents while performing proteolytic digestion. The latter introduced new challenges as seen from the data analysis perspective, since replicate readings are not acquired. 相似文献28.
John E Moore Adrienne Shaw Jennifer L Howard James SG Dooley J Stuart Elborn 《Annals of clinical microbiology and antimicrobials》2004,3(1):1-5
Background
Although various hematologic abnormalities are seen in tuberculosis, immune thrombocytopenic purpura is a rare event.Case Presentation
We report a case of a 29 year-old male who was presented with immune thrombocytopenia-induced hemoptysis, macroscopic hematuria and generalized petechiae. The patient was found to have clinical, microbiological and radiological evidence of active pulmonary tuberculosis. The immune thrombocytopenic purpura was successfully treated with anti-tuberculous drugs combined with corticosteroids and high dose immune globulin therapy.Conclusion
Immune thrombocytopenic purpura can be one of the hematological manifestations of tuberculosis which has a global prevalence with increasing incidence secondary to HIV infection. 相似文献29.
Buddington RK Pajor A Buddington KK Pierzynowski S 《Comparative biochemistry and physiology. Part A, Molecular & integrative physiology》2004,138(2):215-220
Only a small percentage of alpha-ketoglutarate (AKG) administered lumenally to pigs appears in the portal circulation. This has been attributed to mucosal metabolism, and possibly by limited absorption. Although transporters for di- and tricarboxylic acids, which includes the sodium-dependent transporter NaDC-1, have been detected in the small intestine, correlations with functional assays are lacking. Therefore, intact tissues from three regions of the small intestine, stomach, and colon of weaned pigs were used to measure rates of AKG absorption. Western analysis was used to detect NaDC-1 in the three regions of small intestine. Rates of AKG absorption were highest in the small intestine, lowest in the colon, and intermediate in the stomach. Immunoreactive NaDC-1 was detected in the small intestine and this coincided with a component of AKG absorption that was inhibited by AKG and succinate. In contrast, absorption of AKG was inhibitable by unlabeled AKG, but not succinate, in the stomach, and by neither in the colon. Feeding studies indicated that the amounts of AKG that might be included in practical diets for pigs would not (1) upregulate rates of AKG absorption or (2) exceed estimated capacities of the small intestine to absorb AKG. The present findings indicate that the efficacy of AKG as an alternative metabolic fuel for enterocytes to spare dietary amino acids is not limited by absorption. 相似文献
30.
Survival of Escherichia coli K-12 AB1157 irradiated with UVC (UV(254 nm)) was enhanced after pre-treatment with a low-tension electric field (EF). The EF used was identical to the electrical field generated by the small intestine (myoelectrical migrating complex--MMC), registered in a healthy calf and transmitted into the memory of an EF generator. The EF emitted by the generator was transmitted via electrodes placed in shaken bacterial cultures. The protective effects of the EF on the E. coli survival after exposure to UV were: (i) observed only for the dnaJ(+)dnaK(+) strain, and not for the DeltadnaJdnaK heat shock mutant; (ii) strictly dependent on the temperature at which the bacteria were grown; (iii) most obvious when the bacteria were incubated at 37 degrees C. Moreover, the MMC-related EF and a higher temperature (40 degrees C) show a similar protective effect against UV-irradiation. The results point to the involvement of the heat shock response in the low-tension EF-induced protection of bacterial cells against UVC-irradiation. Additionally, treatment with the MMC-related EF affects total protein contents and their pattern in E. coli cells. The EF-treatment did not show any influence on the level of the argE3(ochre) --> Arg(+) reversions. 相似文献