Extracellular prolyl endoprotease from Aspergillus niger and its use in the debittering of protein hydrolysates     

Edens L  Dekker P  van der Hoeven R  Deen F  de Roos A  Floris R 《Journal of agricultural and food chemistry》2005,53(20):7950-7957

The observation that the bitterest peptides from casein hydrolysates contain several proline residues led us to hypothesize that a proline-specific protease would be instrumental in debittering such peptides. To identify the desired proline-specific activity, a microbiological screening was carried out in which the chromogenic peptide benzyloxycarbonyl-glycine-proline-p-nitroanilide (Z-Gly-Pro-pNA) was used as the substrate. An Aspergillus niger (A. niger) strain was identified that produces an extracellular proline-specific protease with an acidic pH optimum. On the basis of sequence similarities, we conclude that the A. niger-derived enzyme probably belongs to the S28 family of clan SC of serine proteases rather than the S9 family to which prolyl oligopeptidases belong. Incubating the overexpressed and purified enzyme with bitter casein hydrolysates showed a major debittering effect. Reversed phase HPLC analysis revealed that this debittering effect is accompanied by a significant reduction of the number of hydrophobic peptides present.  相似文献   

Identification of intra-accession genetic diversity in selfing crops using AFLP markers: implications for collection management     

Rob van Treuren  Theo J.L. van Hintum 《Genetic Resources and Crop Evolution》2001,48(3):287-295

Germplasm conserved as seeds in genebanks requires regular regeneration. In this process, selection and genetic drift may cause loss of genetic diversity from accessions. In the case of selfing crops, separation of distinct lines into different accessions may be an efficient strategy to avoid these negative effects. In order to evaluate the applicability of this method for collection management, knowledge about the level of intra-accession genetic diversity is required. By means of AFLP analysis intra-accession variation was investigated in two cultivars, two landraces and two wild populations of ex situ conserved barley germplasm. In the total sample of 216 individuals analysed (36 per accession), 22 genotypes were observed based on 104 polymorphic loci. The number of genotypes detected ranged from 1 to 3 per accession, except for a Nepalese landrace that revealed 12 genotypes. An UPGMA cluster analysis grouped the genotypes unambiguously into the accession they belonged to and genotypes within accessions were generally found to be closely related. In order to determine the repeatability of the results obtained, 11 individuals belonging to 4 genotypes from the Nepalese landrace were scored for a second set of AFLP markers. Matrices of genetic distances calculated for the two AFLP datasets were found to be highly correlated (r = 0.9346, P < 0.001). Separation of genotypes into different accessions was considered a relevant option only for the Nepalese landrace. Analysis of molecular variance indicated that this accession could be well divided into 8 distinct lines. Further implications of the results for genebank practices are discussed.  相似文献   

Diurnal migration and responses to simulated rainfall in desert soil microarthropods and nematodes     

Walter G. Whitford  Diana W. Freckman  Ned Z. Elkins  Lawrence W. Parker  Rob Parmalee  Janice Phillips  Suzanne Tucker 《Soil biology & biochemistry》1981,13(5):417-425

Diurnal patterns of microarthropod abundance in surface leaf litter were related to its moisture content. Leaf litter moisture was nearly 7% by weight at 0800h but fell to less than 1% by mid-day. Oribatid and tydeid mites moved into litter in the early morning and back into the soil before mid-day. There were no significant differences in numbers of nematodes in litter or soil and 78–98% of the nematodes were anhydrobiotic (coiled) in soil and litter at all times sampled.Following simulated rainfall there were fewer microarthropods in litter at mid-day in the absence of marked decreases in soil and litter moisture content. During drying, there were gradual reductions in numbers and species diversity of litter microarthropods. Nematode numbers did not change as litter dried. Anhydrobiotic nematodes in the soil increased from 14% on day 1 to 85% on day 4. Between 24 and 36 h after simulated rainfall, the proportion of anhydrobiotic litter nematodes increased from 35 to 80%,.Within 1 h after simulated rainfall, there were marked increases in numbers and diversity of microarthropods in surface litter. No collembolans were extracted from dry litter controls but the wet litter was dominated by isotomid, sminthurid and onychiurid collembolans. There were increases in numbers and diversity of oribatid, tydeid and gamasid mites in the wet surface litter within l h after wetting compared to controls.  相似文献   

National Scrapie Plans - the Flock Register     

Paul R 《The Veterinary record》2005,156(23):749-750

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Congress 2004. "The medicine for you and your practice"     

Back R 《Tijdschrift voor diergeneeskunde》2005,130(2):64-66

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A new year--a new future without VKO     

Lubsen R  Jonker S 《Tijdschrift voor diergeneeskunde》2005,130(1):20-21

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Crystal structure of the rabies virus nucleoprotein-RNA complex     

Albertini AA  Wernimont AK  Muziol T  Ravelli RB  Clapier CR  Schoehn G  Weissenhorn W  Ruigrok RW 《Science (New York, N.Y.)》2006,313(5785):360-363

Negative-strand RNA viruses condense their genome into a helical nucleoprotein-RNA complex, the nucleocapsid, which is packed into virions and serves as a template for the RNA-dependent RNA polymerase complex. The crystal structure of a recombinant rabies virus nucleoprotein-RNA complex, organized in an undecameric ring, has been determined at 3.5 angstrom resolution. Polymerization of the nucleoprotein is achieved by domain exchange between protomers, with flexible hinges allowing nucleocapsid formation. The two core domains of the nucleoprotein clamp around the RNA at their interface and shield it from the environment. RNA sequestering by nucleoproteins is likely a common mechanism used by negative-strand RNA viruses to protect their genomes from the innate immune response directed against viral RNA in human host cells at certain stages of an infectious cycle.  相似文献   

Migratory birds and avian flu     

Fergus R  Fry M  Karesh WB  Marra PP  Newman S  Paul E 《Science (New York, N.Y.)》2006,312(5775):845-846

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Clinical, behavioral, and pulmonary changes in calves following inoculation with Mycoplasma bovis     

White BJ  Anderson DE  Renter DG  Larson RL  Mosier DA  Kelly LL  Theurer ME  Robért BD  Walz ML 《American journal of veterinary research》2012,73(4):490-497

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Genome-wide analysis of mitral valve disease in Cavalier King Charles Spaniels     

French AT  Ogden R  Eland C  Hemani G  Pong-Wong R  Corcoran B  Summers KM 《Veterinary journal (London, England : 1997)》2012,193(1):283-286

The Cavalier King Charles Spaniel (CKCS) is prone to severe early onset mitral valve disease. In this study, 36 purebred CKCS dogs were evaluated for mitral valve murmur and divided into early and late onset groups. A genome-wide genetic approach was used to assess whether the condition is determined by a small number of genetic factors. There were no regions of highly discrepant homo/heterozygosity in the two groups. Similarly, there was no evidence for loci associated with mitral valve murmur in a genome-wide association study. This analysis suggests that familial occurrence of mitral valve murmur in the CKCS breed is not due to a single major gene effect, indicating that breeding strategies to eliminate the disease cannot be based on genotype information at this time.  相似文献