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1.
A method was developed to optimize simultaneous selection for a quantitative trait with a known QTL within a male and a female line to maximize crossbred performance from a two-way cross. Strategies to maximize cumulative discounted response in crossbred performance over ten generations were derived by optimizing weights in an index of a QTL and phenotype. Strategies were compared to selection on purebred phenotype. Extra responses were limited for QTL with additive and partial dominance effects, but substantial for QTL with over-dominance, for which optimal QTL selection resulted in differential selection in male and female lines to increase the frequency of heterozygotes and polygenic responses. For over-dominant QTL, maximization of crossbred performance one generation at a time resulted in similar responses as optimization across all generations and simultaneous optimal selection in a male and female line resulted in greater response than optimal selection within a single line without crossbreeding. Results show that strategic use of information on over-dominant QTL can enhance crossbred performance without crossbred testing. 相似文献
2.
Tryptic digestion of human GPIIIa. Isolation and biochemical characterization of the 23 kDa N-terminal glycopeptide carrying the antigenic determinant for a monoclonal antibody (P37) which inhibits platelet aggregation.
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J J Calvete G Rivas M Maruri M V Alvarez J L McGregor C L Hew J Gonzalez-Rodriguez 《The Biochemical journal》1988,250(3):697-704
Early digestion of pure human platelet glycoprotein IIIa (GPIIIa) leads to a single cleavage of the molecule at 23 kDa far from one of the terminal amino acids. Automated Edman degradation demonstrates that GPIIIa and the smaller (23 kDa) tryptic fragment share the same N-terminal amino acid sequence. A further cleavage occurs in the larger fragment (80 kDa), reducing its apparent molecular mass by 10 kDa. The 23 kDa fragment remains attached to the larger ones in unreduced samples. Stepwise reduction of early digested GPIIIa with dithioerythritol selectively reduces the single disulphide bond joining the smaller (23 kDa) to the larger (80/70 kDa) fragments. Two fractions were obtained by size-exclusion chromatography of early digested GPIIIa after partial or full reduction and alkylation. The larger-size fraction contains the 80/70 kDa fragments, while the 23 kDa fragment is isolated in the smaller. The amino acid compositions of these fractions do not differ very significantly from the composition of GPIIIa; however the 23 kDa fragment contains only 10.2% by weight of sugars and is richer in neuraminic acid. Disulphide bonds are distributed four in the 23 kDa glycopeptide and 20-21 in the 80/70 kDa glycopeptide. The epitope for P37, a monoclonal antibody which inhibits platelet aggregation [Melero & González-Rodríguez (1984) Eur. J. Biochem. 141, 421-427] is situated within the first 17 kDa of the N-terminal region of GPIIIa, which gives a special functional interest to this extracellular region of GPIIIa. On the other hand, the epitopes for GPIIIa-specific monoclonal antibodies, P6, P35, P40 and P97, which do not interfere with platelet aggregation, are located within the larger tryptic fragment (80/70 kDa). Thus, the antigenic areas available in the extracellular surface of GPIIIa for these five monoclonal antibodies are now more precisely delineated. 相似文献
3.
Effect of postnatal development on calcium currents and slow charge movement in mammalian skeletal muscle 总被引:16,自引:3,他引:13
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Single- (whole-cell patch) and two-electrode voltage-clamp techniques were used to measure transient (Ifast) and sustained (Islow) calcium currents, linear capacitance, and slow, voltage-dependent charge movements in freshly dissociated fibers of the flexor digitorum brevis (FDB) muscle of rats of various postnatal ages. Peak Ifast was largest in FDB fibers of neonatal (1-5 d) rats, having a magnitude in 10 mM external Ca of 1.4 +/- 0.9 pA/pF (mean +/- SD; current normalized by linear fiber capacitance). Peak Ifast was smaller in FDB fibers of older animals, and by approximately 3 wk postnatal, it was so small as to be unmeasurable. By contrast, the magnitudes of Islow and charge movement increased substantially during postnatal development. Peak Islow was 3.6 +/- 2.5 pA/pF in FDB fibers of 1-5-d rats and increased to 16.4 +/- 6.5 pA/pF in 45-50-d-old rats; for these same two age groups, Qmax, the total mobile charge measurable as charge movement, was 6.0 +/- 1.7 and 23.8 +/- 4.0 nC/microF, respectively. As both Islow and charge movement are thought to arise in the transverse-tubular system, linear capacitance normalized by the area of fiber surface was determined as an indirect measure of the membrane area of the t-system relative to that of the fiber surface. This parameter increased from 1.5 +/- 0.2 microF/cm2 in 2-d fibers to 2.9 +/- 0.4 microF/cm2 in 44-d fibers. The increases in peak Islow, Qmax, and normalized linear capacitance all had similar time courses. Although the function of Islow is unknown, the substantial postnatal increase in its magnitude suggests that it plays an important role in the physiology of skeletal muscle. 相似文献
4.
Structure of an antifreeze polypeptide precursor from the sea raven, Hemitripterus americanus 总被引:4,自引:0,他引:4
The cystine-rich antifreeze polypeptides (AFP) from sea raven were fractionated by reverse-phase high performance liquid chromatography into several components, with SR2 (Mr 17,000) as the major AFP. Sea raven AFP cDNA clones were isolated from a liver cDNA library using a synthetic oligonucleotide, and the identity of one of the clones, C2-1, was confirmed by hybridization selection and cell-free translation. C2-1 encodes a pre-AFP of 195 amino acids with no evidence of any profragments. Comparison of the deduced amino acid sequence with partial peptide sequences from SR2 showed substitutions in at least four amino acid positions, suggesting that C2-1 cDNA codes for a minor component. Both the primary and the predicted secondary structures of sea raven AFP are completely different from those of other fish AFP. This further confirms that sea raven AFP belongs to a different class of antifreezes. The high frequency of reverse turns and the presence of paired hydrophilic amino acids in these structures are striking features of the protein and may contribute to their antifreeze action. 相似文献
5.
Structure of an antifreeze polypeptide and its precursor from the ocean pout, Macrozoarces americanus 总被引:5,自引:0,他引:5
X M Li K Y Trinh C L Hew B Buettner J Baenziger P L Davies 《The Journal of biological chemistry》1985,260(24):12904-12909
Serum antifreeze polypeptides (AFP) from Newfoundland ocean pout have been resolved by ion exchange chromatography and reverse phase high performance liquid chromatography into at least 12 components. The protein sequences of three of the AFP were determined using a combination of protein Edman degradation and cDNA sequencing. The AFP precursor protein encodes for a preprotein of 87 amino acids with no obvious prosequences. Two of the AFP (SP1-A and SP1-C) were separate gene products with minor amino acid sequence differences. The protein structure of SP1-C precursor is MKSVILTGLLFVLLCVDHMTASQSVVAT QLIPINTALTPAMMEGKVTNPIGIPFAEMSQIVGKQVNTPVAKGQTLMPNMVKTYVAGK. The third AFP (SP1-B) is a post-translation modification product of SP1-C. These experiments indicate that the ocean pout AFP are a multigene family with protein structure different from any other known polypeptide antifreezes. 相似文献
6.
Three photosynthetic enzymes were characterised in extractsfrom leaves and aerial roots of Aranda Christine 130.The enzymes from both tissues were similar in activity and kineticproperties. Grana-containing chloroplasts were found in rootcells of Vanda suauis. Thus components crucial to photosynthesisare present in aerial roots of these leafy orchids. (Received March 22, 1983; Accepted July 7, 1983) 相似文献
7.
8.
Antifreeze polypeptides from the Newfoundland ocean pout,Macrozoarces americanus: presence of multiple and compositionally diverse components 总被引:1,自引:0,他引:1
Choy L Hew Don Slaughter Shashikant B. Joshi Garth L. Fletcher V. S. Ananthanarayanan 《Journal of comparative physiology. B, Biochemical, systemic, and environmental physiology》1984,155(1):81-88
Summary Eight major antifreeze polypeptides (AFP) were purified from the sera of Newfoundland ocean pout. Except for their approximately identical size (6,000 Dalton), these components were shown to be separate entities by their behaviour on polyacrylamide gel electrophoresis, ion exchange chromatography, gel permeation and reverse phase high performance liquid chromatography. They could also be divided into two cross-reactive, yet distinct, immunological groups. Amino acid analysis demonstrated that ocean pout AFP are different from all of the other antifreezes studied to date. The ocean pout AFP do not contain the abundance of alanine (60 mol%) found in winter flounder and shorthorn sculpin AFP nor the high half-cystine residues (8 mol%) observed in sea raven AFP. It is suggested that ocean pout AFP represent a new type of macromolecular antifreeze.Abbreviations
AFGP
antifreeze glycoprotein(s)
-
AFP
antifreeze polypeptide(s)
-
HPLC
high performance liquid chromatography
-
SDS
sodium dodecyl sulfate
-
PAGE
polyacrylamide gel electrophoresis 相似文献
9.
A Chakrabartty V S Ananthanarayanan C L Hew 《The Journal of biological chemistry》1989,264(19):11307-11312
The major antifreeze polypeptide (AFP) from winter flounder (37 amino acid residues) is a single alpha-helix. Aspartic acid and arginine are found, respectively, at the amino and carboxyl-termini. These charged amino acids are ideally located for stabilizing the alpha-helical conformation of this AFP by means of charge-dipole interaction (Shoemaker, K. R., Kim, P.S., York, E.J., Stewart, J. M., and Baldwin, R. L. (1987) Nature 326, 563-567). In order to understand these and other molecular interactions that maintain the AFP structure, we have carried out the chemical synthesis of AFP analogs and evaluated their conformations by circular dichroism spectroscopy. We synthesized the entire AFP molecule (37-mer) and six COOH-terminal peptide fragments (36-, 33-, 27-, 26-, 16-, and 15-mers). Peptides containing acidic NH2-terminal residues displayed greater helix formation and thermal stability compared to those peptides of similar size, but with neutral NH2-terminal residues. Helix formation was maximum above pH 9.2. The peptide conformations also displayed a pH-dependent sensitivity to changes in ionic strength. Helix formation was reduced in the presence of acetonitrile. We conclude that the AFP helix is most likely stabilized by: charge-dipole interactions between charged terminal amino acids and the helix dipole, a charge interaction between Lys18 and Glu22 (either a salt bridge or a hydrogen bond), and hydrophobic interactions. 相似文献
10.