Detection of quantitative trait loci for resistance to gastrointestinal nematode infections in Creole goats

This study aimed to identify regions of the genome affecting resistance to gastrointestinal nematodes in a Creole goat population naturally exposed to a mixed nematode infection (Haemonchus contortus, Trichostrongylus colubriformis and Oesophagostomum columbianum) by grazing on irrigated pasture. A genome‐wide quantitative trait loci (QTL) scan was performed on 383 offspring from 12 half‐sib families. A total of 101 microsatellite markers were genotyped. Traits analysed were faecal egg count (FEC), packed cell volume (PCV), eosinophil count and bodyweight (BW) at 7 and 11 months of age. Levels of activity of immunoglobulin A (IgA) and activity of immunoglobulin E (IgE) anti‐Haemonchus contortus L3 crude extracts and adult excretion/secretion products (ESPs) were also analysed. Using interval mapping, this study identified 13 QTL for parasite resistance. Two QTL linked with FEC were found on chromosomes 22 and 26. Three QTL were detected on chromosomes 7, 8 and 14 for eosinophil counts. Three QTL linked with PCV were identified on chromosomes 5, 9 and 21. A QTL for BW at 7 months of age was found on chromosome 6. Lastly, two QTL detected on chromosomes 3 and 10 were associated with IgE anti‐L3, and IgE anti‐ESP was linked with two QTL on chromosomes 1 and 26. This study is the first to have identified regions of the genome linked with nematode resistance in a goat population using a genome scan. These results provide useful tools for the understanding of parasite resistance in small ruminants.     

Reengineering granulocyte colony-stimulating factor for enhanced stability

Granulocyte colony-stimulating factor is a long-chain cytokine that has both biological and therapeutic applications. It is involved in the production and maturation of neutrophilic progenitor cells and neutrophils and is administered to stimulate the production of white blood cells to reduce the risk of serious infection in immunocompromised patients. We have reengineered granulocyte colony-stimulating factor to improve the thermodynamic stability of the protein, focusing on enhancing the alpha-helical propensity of residues in the antiparallel 4-helix bundle of the protein. These redesigns resulted in proteins with substantially enhanced stability while retaining wild-type levels of biological activity, measured as the ability of the reengineered proteins to stimulate the proliferation of murine myeloid cells transfected with the granulocyte colony-stimulating factor receptor.     

Directed mutagenesis confirms the functional importance of positively selected sites in polygalacturonase inhibitor protein

Polygalacturonase inhibitor proteins (PGIPs) protect plants against invasion by diverse microbial and invertebrate enemies that use polygalacturonase (PG) to breach the plant cell wall. Directed mutagenesis has identified specific natural mutations conferring novel defensive capability in green bean PGIP against a specific fungal PG. These same sites are identified as positively selected by phylogenetic codon-substitution models, demonstrating the utility of such models for connecting retrospective comparative analyses with contemporary, ecologically relevant variation.     

Evolution of karyotypic abnormalities and C-MYC oncogene amplification in human colonic carcinoma cell lines

Cell lines (COLO 320 DM and COLO 320 HSR), established from a human neuroendocrine tumor, contain an amplified cellular oncogene (c-myc). We have previously shown that the homogeneously staining regions (HSRs) of a marker chromosome in the COLO 320 HSR cells that evolved in culture from COLO 320 DM cells contain amplified c-myc. Molecular hybridization in situ has now been used to demonstrate that the HSRs are on both arms of what was once an X chromosome. We also show that amplified c-myc copies are present in the isolated double minute chromosomes (DMs) of the COLO 320 DM cells that were characteristic of the tumor cells initially established from the patient. The results suggest that the amplified c-myc appeared first as DMs and was subsequently transposed to engender HSRs on an X chromosome. The initial COLO 320 tumor cell may have acquired two early replicating (i.e., active) X chromosomes and lost the late replicating (i.e., inactive) X.     

Variation between mouse major urinary protein genes isolated from a single inbred line

We describe ten Charon 4A genomic DNA clones from BALB/c mice which include at least seven different major urinary protein (MUP) genes. We have established the orientation of all seven sequences, and have placed six of them in precise register by means of restriction site maps and Southern blot hybridization with cloned cDNA sequences. Four of the seven genomic sequences (family I sequences) form hybrids with six independent cDNA clones that have a high thermal stability and hybridize more strongly with mRNA from three inbred mouse lines. Hybrids between the remaining three genomic sequences and the cDNA clones have a lower thermal stability and hybridize less strongly with mRNA from the three inbred lines. Homologies between different cloned sequences extend over as much as 15 kb. No clone contains parts of two MUP genes, and no homology has been detected between the 3' flanking region of one MUP gene and the 5' flanking region of another.     

Bronchial circulation in pulmonary artery occlusion and reperfusion

Obstruction of pulmonary arterial blood flow results in minimal biochemical and/or morphological changes in the involved lung. If the lung is reperfused, a syndrome of leukopenia and lung edema occurs. We used the radiolabeled microsphere technique to measure the response of the bronchial circulation in rabbits to acute pulmonary artery occlusion (PAO) and to pulmonary artery reperfusion. We found that the bronchial blood flow (Qbr) decreased from a base line of 0.37 +/- 0.10 to 0.09 +/- 0.04 (SE) ml.min-1.g dry lung-1 (P less than or equal to 0.05) after 4 h of PAO. In a separate group of animals, Qbr 24 h after PAO remained low (0.20 +/- 0.07 ml.min-1.g dry lung-1, P = 0.06). Qbr during PAO was inversely correlated with the wet-to-dry ratio after reperfusion (r = -0.68, P = 0.06). Qbr did not change during 4 h of reperfusion. We speculate that a critical level of Qbr may be necessary during PAO to prevent ischemia/reperfusion injury from occurring.     

Kinetics of nucleation-controlled polymerization. A perturbation treatment for use with a secondary pathway

We present a perturbation method for analyzing nucleation-controlled polymerization augmented by a secondary pathway for polymer growth. With this method, the solution to the kinetic equations assumes a simple analytic closed form that can easily be used in fitting data. So long as the formation of polymers by the secondary pathway depends linearly on the concentration of monomers polymerized, the form of the solutions is the same. This permits the analysis of augmented growth models with a minimum number of modeling assumptions, and thus makes it readily possible to distinguish between a variety of secondary processes (heterogeneous nucleation, lateral growth, and fragmentation). In addition, the parameters of the homogeneous process, such as the homogeneous nucleus size, can be determined independent of the nature of the secondary mechanism. We describe applications of this method to the polymerization of actin, collagen, and sickle hemoglobin. We present an extensive analysis of data on actin polymerization (Wegner, A., and P. Savko, 1982, Biochemistry, 21:1909-1913) to illustrate the use of the method. Although our conclusions generally agree with theirs, we find that lateral growth describes the secondary pathway better than the fragmentation model originally proposed. We also show how this method can be used to study the degree of polymerization, the parentage of polymers, and the behavior of polymers in cycling experiments.     

Differential expression in male and female mouse liver of very similar mRNAs specified by two group 1 major urinary protein genes.

The major urinary proteins of the mouse are encoded by a large multigene family composed of several distinct groups of genes distinguished by differences in sequence and expression characteristics. The genes in the largest group (group 1) show greater than 99% pairwise similarity in their exons. By hybridization between RNA and a specifically designed oligonucleotide, we confirmed that genes of this group are expressed mainly in the liver. By using additional gene-specific oligonucleotide probes, we have been able to distinguish between the species of mRNA corresponding to two of these genes and to measure their abundance in male and female liver. Both mRNAs are present in male liver at high but different levels. Both are also present in female liver, one at a much lower level than in the male and the second at a very low level indeed. Both are present at male levels in the livers of females induced with testosterone. These results show unequivocally that the expression of different group 1 Mup genes is differentially influenced by the hormonal status of the mouse.