Genetic characterization of outbred Sprague Dawley rats and utility for genome-wide association studies.

Sprague Dawley (SD) rats are among the most widely used outbred laboratory rat populations. Despite this, the genetic characteristics of SD rats have not been clearly described, and SD rats are rarely used for experiments aimed at exploring genotype-phenotype relationships. In order to use SD rats to perform a genome-wide association study (GWAS), we collected behavioral data from 4,625 SD rats that were predominantly obtained from two commercial vendors, Charles River Laboratories and Harlan Sprague Dawley Inc. Using double-digest genotyping-by-sequencing (ddGBS), we obtained dense, high-quality genotypes at 291,438 SNPs across 4,061 rats. This genetic data allowed us to characterize the variation present in Charles River vs. Harlan SD rats. We found that the two populations are highly diverged (FST > 0.4). Furthermore, even for rats obtained from the same vendor, there was strong population structure across breeding facilities and even between rooms at the same facility. We performed multiple separate GWAS by fitting a linear mixed model that accounted for population structure and using meta-analysis to jointly analyze all cohorts. Our study examined Pavlovian conditioned approach (PavCA) behavior, which assesses the propensity for rats to attribute incentive salience to reward-associated cues. We identified 46 significant associations for the various metrics used to define PavCA. The surprising degree of population structure among SD rats from different sources has important implications for their use in both genetic and non-genetic studies.

Blood and virus detection on barber clippers.

BACKGROUND: Bleeding from the popular clean-shave 'chiskop' haircut was recently reported as prevalent in South Africa (SA), a country with 6.9 million HIV-infected people. OBJECTIVES: To investigate the prevalence of barber hair clipper contamination with blood and HIV and hepatitis B viruses. METHODS: Fifty barbers from three townships in Cape Town, SA, were invited to participate. One clipper from each barber was collected immediately after it had been used for a clean-shave haircut. Each clipper was rinsed with phosphate-buffered saline and then submerged in viral medium. The polymerase chain reaction (PCR) was used to identify the blood-specific RNA marker haemoglobin beta (HBB), hepatitis B virus (HBV) and HIV. RESULTS: The clean-shave haircut was the most common haircut requested by clients (78%). Of the clippers collected, 42% were positive for HBB, confirming detection of blood, none were positive for HIV, and 4 (8%) were positive for HBV. Two clippers (clippers 16 and 20) were positive on qualitative HBV PCR. HBV DNA from clipper 16 clustered with genotype A sequences from SA, India, Brazil and Martinique, while clipper 20 clustered with SA genotype D sequences. The clipper 20 sequence was identical to a subtype D sequence (GenBank accession AY233291) from Gauteng, SA. CONCLUSIONS: This study confirms that there is significant contamination of barber hair clippers with blood and blood-borne viruses. Hepatitis B was detected with enough DNA copies to pose a risk of transmitting infection. Although HIV was not detected in this small study, the risk of transmission should be quantified. Further studies to investigate barber clipper sterilisation practices and whether the clean-shave hairstyle is an independent risk factor for HIV, HBV and hepatitis C virus infections are warranted. Public education on individual clipper ownership (as is the case with a toothbrush) should be advocated for clean-shave and blade-fade haircuts.

Blood and virus detection on barber clippers

Background. Bleeding from the popular clean-shave 'chiskop' haircut was recently reported as prevalent in South Africa (SA), a country with 6.9 million HIV-infected people.Objectives. To investigate the prevalence of barber hair clipper contamination with blood and HIV and hepatitis B viruses.Methods. Fifty barbers from three townships in Cape Town, SA, were invited to participate. One clipper from each barber was collected immediately after it had been used for a clean-shave haircut. Each clipper was rinsed with phosphate-buffered saline and then submerged in viral medium. The polymerase chain reaction (PCR) was used to identify the blood-specific RNA marker haemoglobin beta (HBB), hepatitis B virus (HBV) and HIV.Results. The clean-shave haircut was the most common haircut requested by clients (78%). Of the clippers collected, 42% were positive for HBB, confirming detection of blood, none were positive for HIV, and 4 (8%) were positive for HBV. Two clippers (clippers 16 and 20) were positive on qualitative HBV PCR. HBV DNA from clipper 16 clustered with genotype A sequences from SA, India, Brazil and Martinique, while clipper 20 clustered with SA genotype D sequences. The clipper 20 sequence was identical to a subtype D sequence (GenBank accession AY233291) from Gauteng, SA.Conclusions. This study confirms that there is significant contamination of barber hair clippers with blood and blood-borne viruses. Hepatitis B was detected with enough DNA copies to pose a risk of transmitting infection. Although HIV was not detected in this small study, the risk of transmission should be quantified. Further studies to investigate barber clipper sterilisation practices and whether the clean-shave hairstyle is an independent risk factor for HIV, HBV and hepatitis C virus infections are warranted. Public education on individual clipper ownership (as is the case with a toothbrush) should be advocated for clean-shave and blade-fade haircuts

Inspiratory aerodynamic valving in the avian lung: functional morphology of the extrapulmonary primary bronchus.

The form, geometry and epithelial morphology of the extrapulmonary primary bronchi (EPPB) of the domestic fowl (Gallus gallus var. domesticus) and the rock dove (Columba livia) were studied microscopically and by three-dimensional computer reconstruction to determine the structural features that may be involved in the rectification of the inspired air past the openings of the medioventral secondary bronchi (MVSB), i.e. the inspiratory aerodynamic valving (IAV). In both species, the EPPB were intercalated between the clavicular and the cranial thoracic air-sacs. A notable difference between the morphology of the EPPB in G. g. domesticus and C. livia was that, in the former, the EPPB were constricted at the origin of the MVSB, while a dilatation occurred at the same site in the latter. In both species, a highly vascularized, dorsally located hemispherical epithelial swelling was observed cranial to the origin of the MVSB. The MVSB were narrow at their origin and variably angled relative to the longitudinal axis of the EPPB. Conspicuous epithelial tracts and folds were observed on the luminal aspect of the EPPB in both C. livia and G. g. domesticus. From their marked development and their orientation relative to the angled MVSB, these properties may influence the flow of the air in the EPPB. It was concluded that features such as syringeal constriction, an intimate topographic relationship between the EPPB and the cranial air-sacs, prominent epithelial tracts and folds, an epithelial swelling ahead of the origin of the first MVSB (corresponding to the 'segmentun accelerans'), and narrowing and angulation of the MVSB at their origin, may together contribute to IAV to a variable extent. In as much as the mechanism of pulmonary ventilation and mode of airflow in the parabronchial lung are basically similar in all birds, the morphological differences observed between G. g. domesticus and C. livia suggest that either the mechanism of production of IAV or its functional efficiency may be different, at least in these two species of birds.