Development of a somatic mutation screening system using Hb mutants. IV. Successful detection of red cells containing the human frameshift mutants Hb Wayne and Hb Cranston using monospecific fluorescent antibodies.

The production and purification of antibodies detecting Hb Wayne, an alpha-globin frameshift mutant, and Hb Cranston, a beta-globin frameshift mutant, are described. The antibodies are of a nonprecipitating nature, and they permit strong fluorescent labeling of erythrocytes containing Hb Wayne or Hb Cranston. Studies using artificial mixtures containing cells with either of the two mutants in frequencies ranging from 1 in 10(2) to 1 in 10(5) showed that fluorescent antibodies can detect rare mutant red cells in the presence of vast excesses of normal erythrocytes. On the basis of the structures and the molecular lesions underlying production of the two abnormal hemoglobins, we predict that the anti-Hb Wayne antibody will detect several frameshift mutants resulting from deletion of 3n + 1 nucleotides or insertion of 3n + 2 nucleotides at the 5' side of the codon normally specifying residue 139 of the alpha chain. The anti-Hb Cranston antibody should be capable of detecting beta chains, the corresponding genes of which have sustained insertions of 3n + 2 nucleotides or deletions of 3n + 1 nucleotides on the 5' side of the codon normally specifying residue 144. The two antibodies may, therefore, prove to be valuable in the development of a system aimed at detecting rare erythrocytes that express mutations which arise in the hemopoietic stem cells of normal individuals and subjects exposed to mutagens.     

Detection of quantitative trait loci for meat quality traits in cattle

A whole-genome scan was carried out to detect quantitative trait loci (QTL) affecting sensory, organoleptic, physical and chemical properties of meat. The study used phenotypic data from 235 second-generation cross-bred bull calves of a Charolais × Holstein experimental population. Loin muscle samples were evaluated for yield force, intramuscular fat and nitrogen contents, myofibrillar fragmentation index, haem pigment concentration, moisture content and pH at 24 h postmortem. A sensory assessment was performed on grilled loin and roasted silverside joints by trained panellists. A linear regression analysis based on 165 markers revealed 35 QTL at the 5% chromosome-wide significance level (20 for sensory traits and 15 for physical and chemical traits), five of which were highly significant ( F -value: ≥9). The most significant QTL was located on chromosome 6 (with the best likely position at 39 cM) and affected haem pigment concentration. The Holstein allele for this QTL was associated with an increase of 0.53 SD in the haem scores. A QTL for pH_24h was identified on chromosome 14 (at 40 cM) and a QTL for moisture content was identified on chromosome 22 (at 21 cM). Two highly significant QTL were identified for sensory panel-assessed traits: beef odour intensity (grilled sample) on chromosome 10 (at 119 cM), and juiciness (roast sample) on chromosome 16 (at 70 cM). The proportion of phenotypic variance explained by the significant QTL ranged from 3.6% (for nitrogen content on chromosome 10) to 9.5% (for juiciness, roast sample on chromosome 16).     

Comparative analysis of late floral development and mating-system evolution in tribe Collinsieae (Scrophulariaceae s.l.)

Species of Collinsia and Tonella, the two sister genera of self-compatible annuals that constitute tribe Collinsieae, show extensive variation in floral size and morphology and in patterns of stamen and style elongation during the life of the flower (anthesis). We used a nuclear ribosomal ITS phylogeny, independent contrasts, and phylogenetically corrected path analysis to explore the patterns of covariance of the developmental and morphological traits potentially influencing mating system. Large-flowered taxa maintain herkogamy (spatial separation of anthers and stigmas) early in anthesis by differential elongation of staminal filaments, which positions each of the four anthers at the tip of the "keel" upon dehiscence. Small-flowered taxa do not show this pattern of filament elongation. The styles of large-flowered taxa elongate late in the 2-5 d of anthesis, resulting in late anther-stigma contact and delayed self-pollination. Anther-stigma contact and self-pollination occur early in anthesis in small-flowered species/populations. Thus, we found complex covariation of morphological and developmental traits that can be interpreted as the result of multitrait adaptation for early selfing and high levels of autogamy, delayed selfing and higher levels of outcrossing, or intermediate levels of outcrossing. Continuous variation in these traits suggests the operation of continuous variation in selective optima or the combined effects of divergent selection and phylogenetic inertia.     

Complete amino acid sequence of the gamma chain from the major fetal hemoglobin of the pig-tailed macaque, Macaca nemestrina.

The complete primary structure of the gamma chain of the major fetal hemoglobin from the pig-tailed macaque, Macaca nemestrina, was obtained by the automated sequencing of fragments produced by three nonenzymatic cleavage reactions. About two-thirds of the sequence was established from the amino terminus of the intact chain and two of the three fragments produced by cleavage at methionyl residues by cyanogen bromide. Acid clevage at the single aspartyl-prolyl linkage and cleavage at tryptophanyl residues in intact chains yielded the two fragments necessary to complete the sequence. This gamma chain, the first from a nonhuman primate to be sequenced, differes from the human G gamma and A gamma chains at but 4 and 5 positions, respectively. All substitutions are conservative and unlikely to produce alterations in the oxygen-binding properties of tetrameric fetal hemoglobin. Consideration of the data presented herein, together with published observations made on portions of other primate gamma chains, provides some insight into the evolutionary history of the multiple gamma-globin chains observed in several anthropoid primates.