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951.
952.
Litter size is among the most important traits in swine breeding. However, information on the genetics of litter size in pigs is lacking. In this study, we identified single nucleotide polymorphisms (SNPs) in the insulin-like growth factor binding protein 2 and 3 (IGFBP2 and IGFBP3) genes in Berkshire pigs and analyzed their association with litter size traits. The IGFBP2 SNP was located on chromosome 15 intron 2 (455, A?>?T) and the IGFBP3 SNP was on chromosome 18 intron 2 (53, A?>?G). The AT type of IGFBP2 and the GG type of IGFBP3 had the highest values for all litter size traits including total number born (TNB), number of pigs born alive, and breeding value according to TNB. Homozygous GG pigs expressed higher levels of IGFBP3 mRNA in the endometrium than pigs of other genotypes, and a positive correlation was observed between litter size traits and IGFBP3 but not IGFBP2 expression level. These results suggest that SNPs in the IGFBP2 and the IGFBP3 gene are useful biomarkers for increasing the reproductive productivity of Berkshire pigs.  相似文献   
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956.
Summary Fermentation optimization for the fungus Aspergillus fumigatus F93 was performed to amplify the most promising biological activity. Twelve active variables were analysed and optimized by the Plackett-Burman design, consisting of 16 experiments. Farnesyl protein transferase inhibitory activity showed the best response for the design, and selected parameters were confirmed by separate experiments in the optimized fermentation condition.  相似文献   
957.
Growth-blocking peptide (GBP) has been isolated for the first time from the haemolymph of the host armyworm Pseudaletia separata whose development was halted in the last larval instar stage by parasitization with the parasitoid wasp Cotesia kariyai. Recent studies demonstrated that GBP not only exists in the plasma (haemolymph without cells) of parasitized last instar larvae, but also in the plasma of nonparasitized penultimate (5th) instar larvae. Monoclonal antibodies were prepared to measure the titers of GBP in nonparasitized and parasitized larval plasma. One of three monoclonal antibodies raised against GBP, which is the most specific for GBP, was used to quantify the concentration of plasma GBP. As this antibody recognized two plasma peptides other than GBP in crude plasma fractions, each plasma peptide fraction was separated by a reversed phase HPLC, and then plasma GBP level was measured by ELISA. The highest level of plasma GBP detected on Day 0 of the penultimate instar larvae was gradually decreased throughout the larval growth except for the temporary increase on Day 0 of last larval instar. After parasitization on Day 0 of last larval instar, two peaks of plasma GBP titer were detected during the last larval instar, one day and six days after parasitization. This characteristic increase and decrease in plasma GBP level was also observed by transferring last instar larvae of the armyworm from 25 to 10°C, as a result of which larvae delayed pupation by more than 15 days. From these results, it is reasonable to propose that plasma GBP in lepidopteran larvae might control certain upstream steps in a cascade of events leading to pupation; thus, an elevated level of plasma GBP interferes with normal metamorphosis from larvae to pupae.  相似文献   
958.
A procedure for the regeneration of fertile transgenic Chinese cabbage (Brassica campestris ssp. pekinensis cv. Spring Flavor) is presented in this report. The protocol is based on infection of cotyledon explants of 5-d-old seedlings with an Agrobacterium tumefaciens strain LBA4404 carrying a disarmed binary vector pTOK/BKS-1. The T-DNA region of this binary vector contains the nopaline synthase/neomycin phosphotransferase II (nptII) chimeric gene for kanamycin resistance and the cauliflower mosaic virus 35S/coat protein gene of tobacco mosaic virus L (TMV-L) chimeric gene. After co-cultivation for 48 h, the cotyledonary petioles were placed on shoot induction media containing 15 mg/L kanamycin sulfate. Shoot induction was continued for 3–4 weeks, then subcultured once and after 2 weeks the shoots were transferred to root induction medium. After 1 week 8 putatively transformed plantlets from 200 cotyledon explants were obtained and transferred to greenhouse. Six of them grew to maturity, produced normal flowers and set seeds. Polymerase chain reaction and Southern blot hybridization analyses confirmed the introduction of the T-DNA into the Chinese cabbage genome. Further, Western blot analysis using polyclonal TMV antiserum showed most of the regenerants (5 out of 6) expressed TMV coat protein gene. Stable inheritance of the inserted clone was investigated in the next generation.  相似文献   
959.
o-Succinylbenzoyl coenzyme A (OSB-CoA) synthetase, when treated with diethylpyrocarbonate (DEP), showed a time-dependent loss of enzyme activity. The inactivation follows pseudo-first-order kinetics with a second-order rate constant of 9.2 x 10(-4) +/- 1.4 x 10(-4) microM(-1) min(-1). The difference spectrum of the modified enzyme versus the native enzyme showed an increase in A242 that is characteristic of N-carbethoxyhistidine and was reversed by treatment with hydroxylamine. Inactivation due to nonspecific secondary structural changes in the protein and modification of tyrosine, lysine, or cysteine residues was ruled out. Kinetics of enzyme inactivation and the stoichiometry of histidine modification indicate that of the eight histidine residues modified per subunit of the enzyme, a single residue is responsible for the enzyme activity. A plot of the log reciprocal of the half-time of inactivation against the log DEP concentration further suggests that one histidine residue is involved in the catalysis. Further, the enzyme was partially protected from inactivation by either o-succinylbenzoic acid (OSB), ATP, or ATP plus Mg2+ while inactivation was completely prevented by the presence of the combination of OSB, ATP, and Mg2+. Thus, it appears that a histidine residue located at or near the active site of the enzyme is essential for activity. When His341 present in the previously identified ATP binding motif was mutated to Ala, the enzyme lost 65% of its activity and the Km for ATP increased 5.4-fold. Thus, His341 of OSB-CoA synthetase plays an important role in catalysis since it is probably involved in the binding of ATP to the enzyme.  相似文献   
960.
From the gene library constructed with the chromosomal DNA of 6-mercaptoguanosine (MGS)-resistant strain Brevibacterium ammoniagenes IPR-1, a DNA fragment which conferred MGS-resistance to the wild-type strain B. ammoniagenes ATCC6872 was cloned. The purF gene encoding 5-phosphoribosyl-1-pyrophosphate amidotransferase was identified from this fragment and its nucleotide sequence was determined. Wild type purF gene was also cloned by polymerase chain reaction using chromosomal DNA of ATCC6872 as the template and its sequence was determined. Two nucleotides, 583 A and 1065 A, of MGS-resistant purF gene had been changed from 583 G and 1065 G by mutagenesis, respectively. Both changes at position 583 and 1065 were proved to be responsible for MGS-resistance by site-directed mutagenesis.  相似文献   
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