首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献,搜索用时 31 毫秒
1.
Trypsin inhibitor was extracted from the seed flour of soybean (SB; Glycine max), mung bean (MB; Vigna radiata), cowpea bean (CP; Vigna unguiculata) and adzuki bean (AB; Vigna angularis) using 0.15 M NaCl, followed by heat precipitation at 70 °C. The extract from SB showed the highest specific trypsin inhibitory activity, followed by those from MB, CP and AB, respectively. Based on inhibitory activity staining, molecular weights (MWs) of trypsin inhibitor from SB, MB, CP and AB were 20.1, 14, 10 and 13 kDa, respectively. The SB extract powder (SBEP) containing trypsin inhibitor in the range of 10–100 TIU/g effectively prevented the degradation of γ-, β- and α-chains of collagenolytic proteins of leatherjacket skin subjected to incubation at 50 °C for 30 min. The impact of SBEP on the extraction yield, physical and functional properties of gelatin from leatherjacket skin was investigated. The gelatin extracted in the presence of SBEP contained α1 and α2 chains as the predominant components with some degradation peptides. FTIR spectra indicated the significant loss of molecular order of triple helix and higher degradation was found in gelatin extracted in the absence of SBEP. Gelatin extracted in the presence of SBEP had the higher gel strength (232.8–268.5 g) than that extracted in the absence of SBEP (90.4 g). Higher foam stability (FS) but lower emulsion stability index (ESI) was observed in the former. Therefore, the addition of SBEP effectively prevented the degradation of gelatin from the skin of unicorn leatherjacket, thereby yielding the gelatin with improved gel strength and foam stability.  相似文献   

2.
Screening was carried out for erythorbic acid (EA)-producing strains from about 5,000 newly isolated fungi and bacteria. Penicillium notatum FY 115 was screened out as most powerful EA producer. Only Penicillium, but no other genera, was obtained as EA producers from our screening program. Monospore selections and mutagenic treatments succeeded to elevate the yield of EA over 40% to glucose supplied. Various cultural conditions were studied, and pH change during fermentation process was proved to be most important for favorable EA production. Over 80% yield could be obtained when washed mycelium was used in dilute glucose solution.

Abundant accumulation of EA by the strain FY 115, Penicillium sp., in fermentation broth was studied, and EA, both free and Na-salt, was obtained as crystal in the yield of about 45% to glucose supplied, in the media of 8% glucose by jar fermentor, in considering the inhibitory effect of some metal ion.

Extraction processes were improved to elevate the yield and was developed the continuous multi-bed extraction system of anion-exchange resin, which resulted in the yield of 90.9% of EA from fermentation broth in sum total.  相似文献   

3.
4.
Summary Gelatin, an animal protein derived from collagen has many industrial applications; mainly in food and pharmaceutical products. In this study, enterobacterial contamination of gelatin during different stages of its manufacturing was examined. Since gelatin is extracted in the form of liquor by hot water treatment of ossein and undergoes a complex series of processing stages before being finally blended and packaged off as dry gelatin product, contamination at any stage affects the quality of the final product. In total, 142 samples of gelatin were analysed for the presence of enteric bacteria, which were obtained from different stages of gelatin processing. The Enterobacteriaceae-positive samples were processed and these enterobacterial species were isolated and identified as Proteus mirabilis, Serratia marcescens, E. coli, Salmonella typhi, Klebsiella oxytoca, Klebsiella pneumoniae, Shigella flexneri and Serratia liquefaciens. These were tested for gelatinase activity. The eight species producing maximum gelatinolysis were selected and protease zymography was performed using 1% (w/v) gelatin as a substrate in 7.5% (w/v) acrylamide gel and their molecular weights were determined. The effect of these bacteria on the quality of gelatin was assessed chromatographically in terms of change in amino acid content of gelatin broth inoculated by these species, which showed a marked change with length of incubation. Since these enteric bacteria possess pathogenic properties, some of them are gelatinolytic and also have a significant effect on the quality and amino acid content of gelatin, they are of great concern both for the manufacturers as well as for the consumers.  相似文献   

5.
Characterization of Fish Gelatin at Nanoscale Using Atomic Force Microscopy   总被引:1,自引:0,他引:1  
Atomic force microscopy (AFM) was used as a meaningful tool to characterize the nanostructure of gelatin from catfish (Ictalurus punctatus) skin. The gelatins extracted with pretreatments including acid pretreatment, alkaline pretreatment, and alkaline followed by acid pretreatment (optimized extraction conditions). The resulting gelatins were imaged using AFM and their nanostructure was studied. The AFM images showed that gelatin extracted with acid pretreatment had a coacervate structure while with alkaline pretreatment there were separate aggregates. Spherical aggregates and annular pores were observed in AFM images of gelatin with the optimized extraction conditions. AFM imaging of gelatin with a relative high concentration (0.5%) was successfully done and the results help researchers to understand gelatin structures at the nanoscale.  相似文献   

6.
R. J. Wood 《Genetica》1976,46(3):345-361
Sex ratio in the Trinidad (T-30) strain of Aedes aegypti has remained constant at around 43% during seventeen years of laboratory culture. The divergence from 50% is due to meiotic drive by the M D gene on the Y chromosome. The driving Y chromosome gives a much more distorted sex ratio (mean = 5.7%) when coupled with the highly sensitive X chromosomes from strain 64. This was demonstrated in all of 98 families tested, indicating that all or most of the Y chromosomes in T-30 carry the M D gene. Consequently the low level of sex ratio distortion in T-30 must be due to resistance to M D.Crosses made within T-30 demonstrated wide differences in sex ratio between families, depending on the sensitivity of the male parent's X chromosome to M D. However, sex ratios were not continuously variable but fell within fairly discrete categories. Thus, X chromosomes could be classified according to the modal sex ratios associated with them: m s3 (12.5%), m s2 (32.5%), m s1 (40%), m r1 (47.5%) m r2 (57.5%).The different sex ratio categories were more discrete in the families of sib matings than from random matings, suggesting the possibility of background modification of what is essentially a balanced polymorphism. Evidence is presented suggesting that the polymorphism could be due to interaction at two loci. A further X variant, m s4 (<10%) characterised strain 64 but was absent from T-30.A comparison of fertility between the different sex ratio categories in T-30 established that sex ratio distortion was not caused by differential mortality after fertilisation.  相似文献   

7.
31P nuclear magnetic resonance (NMR) spectroscopy of intact Cosmarium sp. cells is presented as a suitable tool for the differentiation of intracellular accumulation pools of polyphosphates. The cold trichloroacetic acid (TCA) insoluble fraction is shown to contain most of the total cellular phosphate in the phosphate rich Cosmarium cells. Moreover, evidence from a 31 P-NMR study and electron microscopic observations of cold TCA treated Cosmarium cells indicate that this fraction consists mostly of polyphosphates which seem to retain the native morphological structure observed in the untreated cells. The determination of orthophosphate in the hot water extract of Cosmarium cells did not measure the polyphosphate pools. Determination of total phosphorus content in the hot water extract rendered a value three times higher than the frequently used orthophosphate determination procedure. However, as revealed by the 31P-NMR spectra and the chemical analyses of the extract and of the treated cells, even total phosphorus in the extract measured only 30% of the total cellular phosphorus. 31P-NMR enabled the unequivocal chemical identification of the major phosphate compounds in the hot water extract (“Surplus P”) as orthophosphate and polyphosphates of about 10 phosphate units chainlength. More than 70% of the accumulation pool of polyphosphates was still in the cells after extraction. However, the electron microscopy study revealed that the native granular structure of polyphosphates had been destroyed by the hot water extraction procedure.  相似文献   

8.
Rice, IR-28, was fertilized by urea at 48, 96, 144 or 192 kg N/ha under three application schedules: (1) complete basal application before submergence, (2) split application, basal and 30 days after transplanting, or (3) 15 and 45 days after transplanting. Plant growth, yield, N accumulation, and chemical fertilizer N-use efficiency were minimum under complete basal application. N fertilization at 15 and 45 days after transplanting was superior and formed the fastest and greatest colonization by cyanobacteria. The population profile comprised 64%Nostoc, 24%Anabaena and 8%Calothrix.Aulosira, Nodularia andTolypothrix were each less than 1% of the total heterocystous cyano-bacteria.  相似文献   

9.
P-fimbriae, S-fimbriae and AFA-adhesins are virulence factors responsible for adherence ofEscherichia coli strains to extraintestinal host-cell surface. Detection ofpap-,sfa- andafa-specific sequences performed by PCR revealed 74%pap +, 65%sfa +, and 8.3%afa + strains in a group of 84 extraintestialE. coli isolates. Detection in a group of fecal strains showed 29%pap +, 21%sfa + and 4%afa + strains.pap together withsfa were found as the most frequent combination (56%) among extraintestinal isolates probably due to localization ofpap-andsfa-operons on a common pathogenicity island. The occurrence ofafa-specific sequence among 56 urine strains was 11%, although noafa + strain was detected among 28 gynecological isolates. No strains with detected adhesin operons were found among twenty (24%) extraintestinalE. coli strains.  相似文献   

10.
With the purpose of separation and isolation of protein bodies from soybean, soybean seeds were homogenized in oil and fractionated by successively adjusting densities of extracts with carbon tetrachloride. Isolated protein bodies consist of about 10% nitrogen, 0.8% phosphorus, 8.5% sugar, 7% ash and 0.5% RNA. Over 93% of protein in the bodies is found as particle-bound protein which is insoluble in 15% Carbowax 6000 solution but soluble in 10% sodium chloride solution. Protein bodies in intact cells, isolated bodies and those treated with Carbowax 6000 solution were respectively observed by electron-microscopy.  相似文献   

11.
Fragmentation of a dextran from Leuconostoc mesenteroides B* by controlled acetolysis gave five trisaccharides; isomaltotriose (0.12%), 3-α-isomaltosylglucose (0.80%), 6-α-nigero-sylglucose (0.43%), 3,6-di-α-glucosylglucose (0.18%) and nigerotriose (0.12%). Among these trisaccharides the last three were first isolated from dextran. Isolation of nigerotriose indicated that some of the 1,3-linkages in the dextran molecule were contiguous.  相似文献   

12.
《Chronobiology international》2013,30(8):1127-1138
To date, studies investigating the consequences of shiftwork have predominantly focused on external (local) time. Here, we report the daily variation in cognitive performance in rotating shiftworkers under real-life conditions using the psychomotor vigilance test (PVT) and show that this function depends both on external and internal (biological) time. In addition to this high sensitivity of PVT performance to time-of-day, it has also been extensively applied in sleep deprivation protocols. We, therefore, also investigated the impact of shift-specific sleep duration and time awake on performance. In two separate field studies, 44 young workers (17 females, 27 males; age range 20–36 yrs) performed a PVT test every 2?h during each shift. We assessed chronotype by the MCTQShift (Munich ChronoType Questionnaire for shiftworkers). Daily sleep logs over the 4-wk study period allowed for the extraction of shift-specific sleep duration and time awake in a given shift, as well as average sleep duration (“sleep need”). Median reaction times (RTs) significantly varied across shifts, depending on both Local Time and Internal Time. Variability of reaction times around the 24 h mean (≈ ±5%) was best explained by a regression model comprising both factors, Local Time and Internal Time (p < .001). Short (15th percentile; RT15%) and long (85th percentile; RT85%) reaction times were differentially affected by Internal Time and Local Time. During night shifts, only median RT and RT85% were impaired by the duration of time workers had been awake (p?<?.01, consistent with the highest sleep pressure), but not RT15%. Proportion of sleep before a test day (relative to sleep need) significantly affected median RT and RT85% during morning shifts (p?<?.01). RT15% was worst in the beginning of the morning shift, but improved to levels above average with increasing time awake (p < .05), whereas RT85% became worse (p < .05). Hierarchical mixed models confirmed the importance of chronotype and sleep duration on cognitive performance in shiftworkers, whereas the effect of time awake requires further research. Our finding that both Local Time and Internal Time, in conjunction with shift-specific sleep behavior, strongly influence performance extends predictions derived from laboratory studies. (Author correspondence: )  相似文献   

13.
The diet of Antarctic silverfish Pleuragramma antarcticum was evaluated by examining stomach contents of specimens collected in the Ross Sea (71°–77° S; 165°–180° E) in January to March 2008. Pleuragramma antarcticum (50–236 mm standard length, LS) and prey items were analysed for stable‐isotopic composition of carbon and nitrogen. According to index of relative importance (IRI), which incorporates frequency of occurrence, mass and number of prey items, the most important prey items were copepods (81%IRI over all specimens), predominantly Metridia gerlachei and Paraeuchaeta sp., with krill and fishes having low IRI (2·2 and 5·6%IRI overall). According to mass of prey (M) in stomachs, however, fishes (P. antarcticum and myctophids) and krill dominated overall diet (48 and 22%M, respectively), with copepods being a relatively minor constituent of overall diet by mass (9·9%M). Piscivory by P. antarcticum occurred mainly in the extreme south‐west of the region and near the continental slope. Krill identified to species level in P. antarcticum stomachs were predominantly Euphausia superba (14·1%M) with some Euphausia crystallophorias (4·8%M). Both DistLM modelling (PRIMER‐permanova+) on stomach contents (by IRI) and stepwise generalized linear modelling on stable isotopes showed that LS and location were significant predictors of P. antarcticum diet. Postlarval P. antarcticum (50–89 mm LS) consumed exclusively copepods. Juvenile P. antarcticum (90–151 mm LS) consumed predominantly krill and copepods by mass (46 and 30%M, respectively). Small adult P. antarcticum (152–178 mm LS) consumed krill, fishes and copepods (37, 36 and 15%M, respectively). Large adult P. antarcticum (179–236 mm LS) consumed predominantly fishes and krill (55 and 17%M, respectively), especially in the north (near the Ross Sea slope) and in the SW Ross Sea. Amphipods were occasionally important prey items for P. antarcticum (western Ross Sea, 39%M). General concordance between stomach contents and trophic level of P. antarcticum and prey based on δ15N was demonstrated. Pleuragramma antarcticum trophic level was estimated as 3·7 (postlarval fish) and 4·1 (fish aged 3+ years).  相似文献   

14.
A microencapsulated formulation of Helicoverpa armigera nuclear polyhedrosis virus (HaNPV) was produced by emulsion technique to improve its stability under ultraviolet (UV) radiation. The polymers used include sodium alginate, gelatin and starch at concentration levels of 3% and 5% w/v. Except for the starch microencapsulated formulation (3% w/v), the difference in mortality of treated insects between microencapsulated and non-microencapsulated suspensions before irradiation was not significant according to variance analysis (Duncan test, P < 0.05, df = 6). This indicates that microencapsulation of HaNPV does not affect viral activity. Among the three polymers, gelatin performed the best and provided the most stable formulation. The Original Activity Remaining (OAR) percentage for the gelatin formulations did not change from its initial value after 24 h of irradiation. There was no significant difference between the OAR percentage values of 3% and 5% gelatin formulations after 72 h of UVA exposure (90 and 94, respectively; Duncan test, P < 0.05, df = 6). The OAR percentage for the gelatin microencapsulated formulation was 90 after 30 minutes of exposure to UVC radiation. However, for the non-microencapsulated virus suspension, the OAR percentage value declined sharply to 16 after 30 minutes of exposure to UVC radiation. Concerning the in vitro release behaviour of gelatin microparticles (MPs), virus release initiated quickly, but continued at a slower rate until it reached 100% after 1 h of exposure to the release media. The experimental data for the gelatin MPs showed good correlations with the Korsmeyer–Peppas semi-empirical model, indicating that the transport mechanism is primarily consistent with Fickian diffusion.  相似文献   

15.
The stereochemical inversion of (R)-5-hydroxymethyl-3-tert-butyl-2-oxazolidinone (la) or (R)-5-hydroxymethyl-3-isopropyl-2-oxazolidinone (lb) to the corresponding (S)-isomer was accomplished via a key intermediate, (R)-3-N-ethoxycarbonyl-N-tert-butylamino-l,2-epoxypropane (5a) or (R)-3-N-ethoxycarbonyl-N-isopropylamino-l,2-epoxypropane (5b), in a high enantiomeric excess. (S)-la (99%e.e.) or (S)-lb (91%e.e.) was thus obtained from the respective (R)-isomer (la; 99%e.e., lb; 95%e.e.).  相似文献   

16.
German Landrace pigs (n= 1500) were halothane-tested and blood samples were taken for the determination of A-O and H blood types as well as for the determination of PHI and 6-PGD isozymes. The pigs originated from two generations (7th and 8th) of a selection experiment ‘selection for activity of NADPH-generating enzymes in backfat of pigs’. The selection lines are E-, E+ (selection for low and high enzyme activity), U- (selection for low ultrasonic backfat thickness) and K (control). Preliminary results show an average proportion of halothane-susceptible animals of 49 %. The frequencies of halothane-positive pigs amount to 60 %, 46 %, 70 % and 30 % in lines E-, E+, U- and K, respectively. The investigation shows a non-random combination of the marker genes caused by linkage disequilibrium, especially in line E-. Recombination frequencies between the loci vary from 0 % to 18 %.  相似文献   

17.
The utilization of waste has gained momentum in the field of waste management and industrial bioprocess. In this study, waste chicken feet were used as the source for extraction of a natural inducer, i.e. gelatin for the synthesis of proteolytic enzyme gelatinase. Microorganisms with gelatinolytic activity were screened from mixed culture isolates obtained from a local poultry waste dumping site. The strain which had shown maximum activity was identified as Brevundimonas vesicularis MF276770 using 16S rRNA gene sequencing. The composition of chicken feet gelatin was analysed and further characterized by Fourier transform infrared analysis and SDS-PAGE. The maximum gelatinase activity of 18.8?U/mL was achieved for the isolated Brevundimonas vesicularis MF276770 at 12?h under optimized conditions of pH 7, substrate concentration (2%), inoculums age (12?h), inoculum volume (2%, v/v), temperature (50?°C) and RPM (140). The enzyme kinetics parameters Vmax and Km were observed as 7.4?U/mL and 0.422 µmol, respectively. The molecular weight of the produced gelatinase was determined as 67?kDa. The produced gelatinase was employed to strip the gelatin silver layer from X-ray polyester film with 1.93?U/mL of gelatinase activity.  相似文献   

18.
To examine the possibility of dietary α‐starch in reducing feed costs in a practical diet, α‐starch was supplemented at 10, 20, 30 and 40% in a composed diet having the same protein level. The four diets were fed to ayu, Plecoglossus altivelis (initial weight 9.1 g) for 43 days. Growth and feed efficiency increased with the supplement, with values highest in the 30–40%α‐starch diet. The level of dietary α‐starch did not affect the proximate muscle composition; although the hepatosomatic index was not affected, liver glycogen increased with increasing dietary α‐starch. The dietary α‐starch did not influence evacuation time from the gut, and was well digested through passage in the gut, mainly between the stomach and the anterior part of the intestine. Ayu have an ability to adapt their metabolism to high dietary α‐starch, and can digest 40% or more in a composed diet. Although the muscle lipid content did not change, the fatty acid composition was influenced by dietary starch. With the elevation of dietary starch, a decrease of C18:2n‐6 and an increase of C22:6n‐3 occurred. These results indicate that at least 40%α‐starch can be used in practical diets for ayu.  相似文献   

19.
Ek C  Whary MT  Ihrig M  Bravo LE  Correa P  Fox JG 《Helicobacter》2012,17(2):107-115
Background: Helicobacter pylori‐infected children from coastal Tumaco, Colombia, have more parasitism, and adults have lower gastric cancer risk compared with high‐altitude Pasto/Tuquerres residents. Because helminth and Toxoplasma gondii infections alter helicobacter gastritis in rodent models, we determined whether seropositivity to Ascaris lumbricoides or T. gondii was associated with Th2‐IgG1 or Th1‐IgG2 responses to H. pylori. Methods: Sera (240) from the two populations were evaluated for A. lumbricoides and T. gondii seropositivity and results correlated with IgE and IgG isotype responses to H. pylori. Results: Most Tumaco children and adults were seropositive for A. lumbricoides (89%, 66%), T. gondii (59%, 98%), or both (45%, 66%). In contrast, seropositivity among Pasto/Tuquerres children was much lower (9%A. lumbricoides, 11%T. gondii, and 2% dual positive) but increased in adults (58%A. lumbricoides, 82%T. gondii, and 41% dual positive). A. lumbricoides seropositivity correlated with elevated IgE and anti‐inflammatory Th2‐IgG1 responses to H. pylori, while T. gondiigondii seropositivity was linked to elevated IgE, pro‐inflammatory Th1‐IgG2, IgG3, and IgG4 responses to H. pylori. Individuals with high T. gondii titers had reduced Th1‐IgG2, IgG3, and IgG4 responses to H. pylori. Conclusions: Results support regional differences for childhood parasitism and indicate A. lumbricoides and T. gondii infections may impact inflammatory responses to H. pylori and partially explain differences in gastric cancer risk in Colombia.  相似文献   

20.
The mite Varroa jacobsoni was reared in artificial gelatin cells under laboratory conditions and the possible presence of factors inhibiting Varroa reproduction was studied. In cells infested with three mites, the mean offspring per female was reduced to 75% of that in singly infested cells. When gelatin cells were used for two successive rearing cycles, both the proportion of reproducing females and the offspring per reproducing female were significantly lower in cells that had contained an infested larva during the first rearing cycle than in those with an uninfested larva. The mean reduction of the offspring per female was 48%; this suggests that inhibitors of the reproduction are released into infested cells. Treatment of gelatin cells with the hexane extract of cells in which an infested bee pupa had developed caused a 21% reduction in the mean offspring per female, with a difference close to the significance level (p=0.07).  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号