The composition and stability of the faecal microbiota of Merino sheep.

AIMS: To determine the composition and temporal stability of the gut (faecal) microbiota of sheep (Ovis aries). METHODS AND RESULTS: Microbial population dynamics was conducted using ARISA (28 sheep) and 16S rRNA sequencing (11 sheep). Firmicutes and Bacteroidetes were the predominant bacterial phyla, constituting ~80% of the total population. The core faecal bacterial microbiota of sheep consisted of 67 of 136 detected families and 91 of 215 detected species. Predominant microbial taxa included Ruminococcaceae, unassigned families in Bacteroidales and Clostridiales, Verrucomicrobiaceae and Paraprevotellaceae. Diversity indices and core microbiota composition demonstrated the stability of the core microbiota over 2-4 weeks. The core microbiota remained similar over ~5 months. CONCLUSIONS: Temporal stability of the sheep microbiota is high over 2-4 weeks in the absence of experimental variables. The core microbiota of Merino sheep shares taxa found in other breeds of sheep and other ruminants. SIGNIFICANCE AND IMPACT OF THE STUDY: Numerous studies seek to investigate the impact of experimental variables on gut microbiota composition. To do so, knowledge of the innate stability (or instability) of the microbiota over an experimental time course is required, independent of other variables. We have demonstrated high stability of the gut microbiota in sheep over 3-4 weeks, with moderate stability over ~5 months.

Increased risk of allergy in children due to formaldehyde exposure in homes.

BACKGROUND: Formaldehyde levels were measured in 80 houses in the Latrobe Valley, Victoria, Australia. An association between exposure to formaldehyde and sensitization to common aeroallergens has been suggested from animal trials, but no epidemiologic studies have tested this hypothesis. METHODS: A total of 148 children 7-14 years of age were included in the study, 53 of whom were asthmatic. Formaldehyde measurements were performed on four occasions between March 1994 and February 1995 with passive samplers. A respiratory questionnaire was completed, and skin prick tests were performed. RESULTS: The median indoor formaldehyde level was 15.8 microg/ m3(12.6ppb), with a maximum of 139 microg/m3 (111 ppb). There was an association between formaldehyde exposure and atopy, and the adjusted odds ratio was 1.40 (0.98-2.00, 95% CI) with an increase in bedroom formaldehyde levels of 10 microg/m3. Furthermore, more severe allergic sensitization was demonstrated with increasing formaldehyde exposure. On the other hand, there was no significant increase in the adjusted risk of asthma or respiratory symptoms with formaldehyde exposure. However, among children suffering from respiratory symptoms, more frequent symptoms were noted in those exposed to higher formaldehyde levels. CONCLUSIONS: Low-level exposure to indoor formaldehyde may increase the risk of allergic sensitization to common aeroallergens in children.

Indoor airborne fungal spores, house dampness and associations with environmental factors and respiratory health in children.

BACKGROUND: Children living in a damp house are more likely to suffer from respiratory symptoms and it has been suggested that exposure to fungi is an important contributing factor. However, more knowledge about underlying mechanisms for the association are needed. OBJECTIVE: To identify associations between measures of house dampness, levels of airborne fungal spores, housing factors and health outcomes in children. METHODS: Eighty households with 148 children between 7 and 14 years of age were recruited in the Latrobe Valley, Victoria, Australia. Some 36% of participating children were asthmatic. Six sampling visits were made to each house between March 1994 and February 1995 on a 2-monthly cycle. Samples for airborne total and viable fungal spores were collected from bedrooms, living rooms, kitchens and outdoors. A detailed dwelling characterization, using a questionnaire and inspection surveys, was carried out. Skin-prick tests were performed with extracts of common aeroallergens and a respiratory questionnaire was completed for each child. RESULTS: Large airborne fungal spore concentrations were recorded in association with: musty odour, water intrusion, high indoor humidity, limited ventilation through open windows, few extractor fans and failure to remove indoor mould growth. Visible mould growth or condensation evidence was associated with large concentrations of Cladosporium spores, but not with large total spore concentrations. Penicillium exposure was a risk factor for asthma, while Aspergillus exposure was a risk factor for atopy. Fungal allergies were more common among children exposed to Cladosporium or Penicillium in winter or to musty odour. Respiratory symptoms were marginally more common with exposure to Cladosporium or total spores in winter. CONCLUSION: Indoor exposure to certain fungal genera in winter was a risk factor for asthma, atopy and respiratory symptoms in children. On the other hand, no significant associations were seen between average viable or total spore concentrations and child health. Actual measurements of fungal spores predict health outcomes better than reported dampness.

The preparation of an ovine monoclonal antibody to progesterone.

Peripheral blood mononuclear cells were collected from a sheep immunized against progesterone-11 alpha-hemisuccinate-ovalbumin. Following fusion with NS1 mouse myeloma or heteromyeloma cells, a large number of hybrid colonies was established. These were screened for the production of sheep antibodies to progesterone. Twenty-four cell lines were cloned and one was stabilized. This cell line, O/MP.1A9.D7B2, produced a high-affinity ovine immunoglobulin G1 (dissociation constant 4.8 pmol/l) with a high degree of specificity for progesterone. The antibody was substituted into a competitive enzyme-linked immunosorbent assay for the measurement of progesterone in bovine milk, originally established using an ovine polyclonal antibody, and the results were compared. The monoclonal antibody produced an assay with a lower limit of detection and a greater degree of discrimination than the polyclonal antiserum.