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81.
Chitin and chitosan oligosaccharides (COS) have been traditionally obtained by chemical digestion with strong acids. In light of the difficulties associated with these traditional production processes, environmentally compatible and reproducible production alternatives are desirable. Unlike chemical digestion, biodegradation of chitin and chitosan by enzymes or microorganisms does not require the use of toxic chemicals or excessive amounts of wastewater. Enzyme preparations with chitinase, chitosanase, and lysozymeare primarily used to hydrolyze chitin and chitosan. Commercial preparations of cellulase, protease, lipase, and pepsin provide another opportunity for oligosaccharide production. In addition to their hydrolytic activities, the transglycosylation activity of chitinolytic enzymes might be exploited for the synthesis of desired chitin oligomers and their derivatives. Chitin deacetylase is also potentially useful for the preparation of oligosaccharides. Recently, direct production of oligosaccharides from chitin and crab shells by a combination of mechanochemical grinding and enzymatic hydrolysis has been reported. Together with these, other emerging technologies such as direct degradation of chitin from crustacean shells and microbial cell walls, enzymatic synthesis of COS from small building blocks, and protein engineering technology for chitin-related enzymes have been discussed as the most significant challenge for industrial application. 相似文献
82.
Kim Hyoung-Bum ;Kim Seoung-Jun ;Tu Xin-Cheng ;Park Seung-Ha ;Kim Seoung-Jun ;Tu Xin-Cheng ;Park Seung-Ha 《排灌机械》2014,(5):369-372
The effect of streamwise vortices generated from passive vortex generators was investigated to manipulate the separation bubble behind the vertical fence. The experiments were carried out in a circulating water channel and the velocity fields were measured using 2D and stereoscopic PIV method.The distance between the vortex generator and fence and the effect of the Reynolds number were investigated. In addition,the effect of boundary layer thickness was also investigated. The averaged recirculation lengths were compared with that of uncontrolled fence flow. The results showed the oscillatory variation of recirculation region appeared under the existence of vortex generators. The reduction of the separation bubble became larger when the fence was submerged in the thick boundary layer with increasing the distance between the generator and fence. When the boundary layer is thin,vortex generator can only suppress the separation bubble under the specific condition. 相似文献
83.
Han SY Kang BK Kang BJ Shin SP Soen BH Kim JM Kim JH Choresca CH Han JE Jun JW Park SC 《Journal of fish diseases》2011,34(10):731-739
The prevalence of two serotypes of Streptococcus parauberis isolated from the olive flounder, Paralichthys olivaceus, was evaluated in a total of 29 isolates between 2003 and 2010 in Korea. Streptococcus parauberis isolates were divided into two serologically distinct types (serotype 1 and serotype 2), except for one strain (S1091), using an agglutination assay with rabbit antiserum, and serotype 1 was identified as the dominant type (24 of 29 isolates) in this study. To identify the characteristics of the two serotypes of S. parauberis, we conducted a biochemical test using the API 20 Strep kit, a transmission electron microscopy (TEM) assay, sequence analysis of 16S‐23S rRNA intergenic spacer region (ISR) and a pathogenicity test. In TEM, both serotypes possessed polysaccharide capsule layers around the cell surface when bacterial cells were treated with a homologous serotype of rabbit antiserum. However, we were unable to discriminate serotype‐specific biochemical characteristics and genetic characteristics of 16S‐23S rRNA ISR between the two serotypes. In the pathogenicity test, the serotype 1 strains induced significantly higher mortality than the serotype 2 strains in olive flounder when experimentally inoculated via the intraperitoneal route. 相似文献
84.
Kim HJ Suh HJ Kim JH Park S Joo YC Kim JS 《Journal of agricultural and food chemistry》2010,58(22):11633-11638
The extract of soybean exposed to biotic elicitors such as food-grade fungus is known to have antioxidant activity. Glyceollins were major bioactive compounds present in soybean elicited by fungi and shown to have antifungal and anticancer activities. The purpose of present study was to evaluate the antioxidant activities of glyceollins by measuring ferric reducing antioxidant power (FRAP), 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging, singlet oxygen quenching, 2,2'-azinobis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) radical scavenging, hydroxyl radical scavenging activity, and lipid peroxidation inhibition. In addition, the antioxidant potential of glyceollins were measured by a fluorescent probe, 2',7'-dichlorofluorescin diacetate (DCFDA), and dihydroethidium (DHE) in mouse hepatoma hepa1c1c7 cells in which they were insulted with H2O2 to generate reactive oxygen species (ROS). Glyceollins showed a strong reducing power and inhibited lipid peroxidation, with significant scavenging activities of radicals including singlet oxygen, superoxide anion, ABTS, and DPPH. We also found that glyceollins significantly suppressed H2O2-induced ROS production in hepa1c1c7 cells. Therefore, glyceollins deserve further study as natural antioxidants and nutraceuticals. 相似文献
85.
Jeonghwan Park Harry V. Daniels Sung Hwoan Cho 《Journal of the World Aquaculture Society》2013,44(5):726-734
This study was performed to estimate the nitrite toxicity to southern flounder, Paralichthys lethostigma, in brackish water (7.5 ppt of salinity). For a LC50 test, 20 fingerlings (5.7 ± 0.4 cm) in each aquarium (15 L) were exposed to the concentrations of 0, 1, 5, 10, 15, 30, 60, 120, and 240 mg NO2?‐N/L in duplication for 10 d. Median lethal concentration at 96 h (96‐h LC50) was calculated as 81.6 mg NO2?‐N/L. For a verification test, young flounder (164.2 ± 9.1 g) were exposed to a simulated culture condition in recirculating systems (1000 L). Sodium nitrite was not added to control system, whereas it was added to Treatment system 1 (TS 1) and Treatment system 2 (TS 2) to maintain nitrite concentrations of 20 and 30 mg NO2?‐N/L, respectively. The plasma nitrite concentrations of the young flounder in TS 1 and TS 2 were 4.5 and 6.6 mg NO2?‐N/L, respectively, after 2 wk. At this time, the methemoglobin percentages in TS 1 and TS 2 reached 85.8 and 89.7%, and survival rates were 37.5 and 25.0%, respectively. The results of these tests indicate that southern flounder do not concentrate nitrite in blood from the environment, but they seem to be more sensitive to nitrite compared with other species that do not concentrate nitrite. 相似文献
86.
87.
Twelve healthy two-month-old Landrace x Yorkshire pigs of both sexes were randomly assigned to receive either tiletamine and xylazine (zx) or zolazepam and xylazine followed 20 minutes later by yohimbine (zxy). The pigs' scores for immobilisation and analgesia, and their rectal temperature, heart rate, respiration rate, pO(2), pCO(2), alkaline phosphatase, aspartate aminotransferase, glucose and total plasma proteins were determined before and five, 25, 45, 65 and 85 minutes after the administration of the tiletamine/zolazepam and xylazine. The mean total scores for immobilisation and analgesia of the zxy pigs were significantly lower than those of the zx pigs after 85 minutes. The mean rectal temperatures of the zxy pigs were significantly lower than those of zx pigs after 25, 45 and 65 minutes. The mean respiratory rates of the zx pigs were significantly lower than those of zxy pigs after five minutes. The mean pCO(2) of the zxy pigs were significantly lower than those of zx pigs five minutes after the administration of yohimbine. The mean glucose concentration of the zxy pigs were significantly lower than those of zx pigs after 65 and 85 minutes. The mean concentration total protein of the zxy pigs were significantly lower than those of zx pigs throughout the period of anaesthesia. Both groups became laterally recumbent within three minutes. When recovering from anaesthesia, the pigs treated with yohimbine took significantly less time to achieve sternal recumbency (mean [sd] 52.2 [8.9] v 76.2 [20.6] minutes) and less time to be able to stand (mean [sd] 77.0 [9.8] v 98.7 [15.8] minutes), and walk (mean [sd] 81.3 [11.3] v 110.8 [18.6] minutes). 相似文献
88.
89.
Characterization of waxy grain sorghum lines in relation to granule-bound starch synthase 总被引:4,自引:0,他引:4
The waxy phenotype, associated with endosperm containing little or no amylose, has been recognized in sorghum (Sorghum bicolor L. Moench) since 1933. Although variants of the waxy gene are well characterized in other cereals, the waxy trait has been
assumed to be controlled by a single allele, wx, in sorghum. Recent improvements in technologies encourage re-examination of the waxy sorghums. The objectives of this research
were therefore to identify and characterize sorghum lines with differing waxy alleles and to describe the actions of those
alleles in crosses. Grain of eight waxy sorghum lines (BTxARG1, BTx630, Tx2907, B.9307, 94C274, 94C278, 94C289, 94C369), three
wild-type checks (BWheatland, RTx430, BN122), and F2 families from crosses among a subset of these lines were evaluated for presence or absence of granule-bound starch synthase
(GBSS), the gene product of the wx locus, and wild-type vs. waxy endosperm. The F2 segregation ratios were tested for fit to a 3:1 ratio using Chi-square analyses. Two distinctly different naturally occurring
waxy alleles were identified: One with no GBSS (GBSS−), and one with apparently inactive GBSS present (GBSS+). We propose
that the waxy allele with no GBSS be designated wxa, and that waxy allele with apparently inactive GBSS present be designated wxb. These two alleles are located in close proximity on the waxy locus. The wxb allele is dominant to the wxa allele in terms of GBSS production, and both are recessive to the wild-type Wx in terms of amylose content.
The U.S. Government's right to retain a non-exclusive, royalty-free license in and to any copyright is acknowledged. 相似文献
90.
Karyotype of Canada wildrye (Elymus canadenisis L.) was described using giemsa C-banding techniques. Most of the chromosomes showed dome banding pattern polymorphism. Small to large terminal and centormere bands were observed in most of the chromosomes. A faint satellite was observed in one chromosome. Tow chromosomes had a large interstitial band near the centromeres in the long arms. The Giemsa C-banding pattern of E. Canadensis is compared to that of Pseudoroegneria spicata and Critesion boddanii to illustrate species relationship. 相似文献