Microsatellite characterization of subspecies and their hybrids in Culex pipiens complex (Diptera: Culicidae) mosquitoes along a north-south transect in the central United States

Mosquitoes in the Culex pipiens complex, Cx. p. pipiens L. and Cx. p. quinquefasciatus Say are morphologically similar and important vectors of West Nile and St. Louis Encephalitis viruses in the United States. The subspecies differ with respect to overwintering strategies, with Cx. p. pipiens entering diapause in response to winter conditions and Cx. p. quinquefasciatus lacking this ability, yet they hybridize when found in sympatry. Specimens (n = 646) were collected using gravid traps set along a transect from New Orleans, LA, to Chicago, IL. Microsatellite markers were used to: genetically characterize subspecies and hybrids, determine the degree and extent of hybridization to better define the hybrid zone, and examine the efficacy of hybrid detection between microsatellites and a single-gene assay based on the acetylcholinesterase.2 gene (HotAce.2). The results support the presence of two distinct genetic entities, with abroad, stable hybrid zone in between. Admixture analyses classified >40% of individuals as hybrids. Allelic richness was markedly different at the northern and southern ends of the transect, and there was a significant isolation by distance effect. The hybrid zone seems to be wider and extends further to the south than previous work indicated, and as a result, we propose new boundaries compared with those indicated by a previous study. Microsatellites detected more hybrids than the HotAce.2 assay, although the latter assay remains useful as a screening tool. We suggest that the parental subspecies and the hybrid zone are maintained by heterosis combined with selection for diapause at northern latitudes.

Regulation of insulin-like growth factor binding protein-5 mRNA abundance in rat intestinal smooth muscle

IGF-I increases abundance of IGFBP-5 mRNA in rat intestinal smooth muscle cells (RISM), and IGFBP-5 protein in RISM conditioned media. The translational blocker, cycloheximide, decreased the abundance of IGFBP-5 mRNA to undetectable levels, suggesting that IGFBP-5 mRNA integrity is linked to protein synthesis. We studied the mechanism of IGF-I's effect on IGFBP-5 mRNA, and the role of cytoplasmic proteins in modulating IGFBP-5 mRNA abundance. Anisomycin, emetine, and puromycin abolished IGFBP-5 mRNA as seen with cycloheximide. Cycloheximide had a dose- and time-dependent effect on IGFBP-5 mRNA. IGF-I increased IGFBP-5 nuclear transcripts by reverse transcription-polymerase chain reaction (RT-PCR), suggesting that IGF-I acts at least partially by increasing IGFBP-5 mRNA transcription. Protein synthesis inhibitors did not affect IGFBP-5 nuclear transcripts, therefore, they affect only mature mRNA. The IGFBP-5 mRNA 3' and 5' UTRs were cloned and their sequences searched for adenosine-uridine rich elements (AUREs), elements shown to regulate RNA stability. RNA mobility gel shift assay showed two protein activities that bind to nt 922 to 2076 of the 3' UTR, a region that contains an AURE. One protein activity (BA2) was decreased in cytoplasmic extracts from cycloheximide-treated RISM. These data demonstrate that IGFBP-5 mRNA integrity is dependent on protein synthesis. The 3' UTR of IGFBP-5 contains elements shown to bind proteins important for RNA stability regulation. This region binds RISM cytoplasmic proteins, and may mediate the dramatic effect of cycloheximide on IGFBP-5 abundance. RNA-protein interactions may be important to IGFBP-5 mRNA stability and ultimately, to IGFBP-5 actions.

Cloning and chromosomal localization of a gene (GPR18) encoding a novel seven transmembrane receptor highly expressed in spleen and testis

Using the techniques of relaxed stringency polymerase chain reaction and genomic library screening, we have isolated homologous canine and human genes that encode a novel putative seven transmembrane G-protein-linked receptor. The gene encodes an open reading frame (ORF) of 993 bp. The sequences of the canine and human ORFs are highly conserved, sharing 89% nucleotide identity and 92% amino acid similarity between the two species. Northern blot analysis demonstrates that mRNA transcripts of the gene are abundantly expressed in testis and spleen with a lesser degree of expression observed in several other tissues associated with endocrine and immunologic/hematologic function. The gene, designated GPR18, was localized to human chromosome 13q32 using fluorescence in situ hybridization.

Detection and prevention of cardiac risk factors: health risk assessment and targeted follow-up in a managed care population

Health risk assessment, developed as a clinical tool for the practice of prospective medicine, has been used primarily in worksite health promotion programs to identify cardiac and other risk factors and to plan preventive actions. This article describes the application of a brief health risk assessment with targeted follow-up to a managed care population, randomized by primary care physicians into usual care and special intervention groups. Study design, methods, and preliminary baseline data on participants are presented, and key learnings about administration of this type of program in an integrated health care system are discussed.

Health hazards to humans associated with domestic pets

Allergy to pets, particularly when manifested as asthma, is an important health hazard. The health impact of severe clinical disease associated with allergy to pets can be minimized by avoidance of pets. Many individuals with milder disease keep their pets and obtain medications for relief of their allergy symptoms. Bird fancier's disease can result in profound deterioration of pulmonary function, and requires avoidance of bird exposure. Animal bites are the commonest health hazard of domestic pets and result in tissue damage and infection risk. Bites are treated by cleaning the wound, and appropriate use of antibiotics and tetanus prophylaxis. Diverse infectious diseases are transmitted to humans by their pets; these diseases are particularly dangerous to immunocompromised individuals. The infectious diseases can be partly prevented by avoiding ill animals and by washing of hands following exposure to pets or pet-derived secretions. They can be treated by appropriate antibiotics and/or specific immune globulins and/or vaccines.

A novel mutation in medium chain acyl-CoA dehydrogenase causes sudden neonatal death

Medium chain acyl-CoA dehydrogenase (MCAD) deficiency is the most common known genetic disorder of fatty acid oxidation. Most (approximately 80%) cases are homozygous for a single mutation: A to G replacement at nucleotide 985 (A985G). MCAD deficiency typically presents in the second year of life as hypoketotic hypoglycemia associated with fasting and may progress to liver failure, coma, and death. Prompt diagnosis and management may prevent long-term sequelae. MCAD deficiency was verified by analysis of urinary acylglycine and serum acylcarnitine species from two neonates referred for diagnosis. Full-length cDNA and MCAD exon 7 and 11 genomic clones were prepared for sequence analysis. Normal and mutant cDNAs were expressed in bacteria, and enzymatic activity was assayed by the ferricenium hexaflurophosphate method. Four compound heterozygote individuals from two unrelated families with A985G on one allele and a novel G to A mutation at nucleotide 583 (G583A) as the second mutant allele presented with MCAD deficiency in the first week of life. The expressed G583A mutant protein lacks enzymatic activity. This novel mutation, G583A, is associated with severe MCAD deficiency causing hypoglycemia or sudden, unexpected neonatal death. This previously unrecognized phenotype of MCAD deficiency may contribute significantly to preventable infant deaths.

Uptake, metabolism, and persistence of 3-methylcholanthrene in rat embryo cells infected with murine leukemia virus

The uptake and persistence of 3-methylcholanthrene have been followed in both unifected rat embryo tissue culture cells and in cells infected with type C RNA virus. No significant differences in these parameters were observed as a function of viral infection or cell passage level. Moreover, neither binding of 3-methylcholanthrene to nucleic acids or proteins nor carcinogen metabolism were altered by the viral carrier state. Although transformation of rat cells by chemical carcinogens alone has been reported by us and other authors, the low-passage rat embryo cells used in this study will not transform unless cells are carrying exogenous type C RNA virus. We thus suggest that the virus must play a more direct role in the transformation process rather than affecting the ability of the cell to absorb, retain, or metabolize the chemical.