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.

Molecular cloning of three cDNAs encoding aminopeptidases from the midgut of Helicoverpa punctigera, the Australian native budworm.

Three cDNAs encoding aminopeptidases HpAPN1, HpAPN2 and HpAPN3, were isolated from a 5th instar larval midgut cDNA library from Helicoverpa punctigera, the Australian native budworm. The sequences recovered contain open reading frames encoding proteins of 1011, 952, and 1013 amino acids, respectively. All three proteins share the consensus zinc binding/gluzincin motif HEXXHX(18)E and the sequence GAMEN common to gluzincin aminopeptidases. Furthermore, signal peptide sequences and C-terminal hydrophobic regions preceded by three small amino acids qualifying for cleavage and GPI anchor attachment are present in all three protein sequences. Northern blotting results indicate differences in the levels of expression and developmental regulation of all three aminopeptidases. HpAPN1, HpAPN2, and HpAPN3 are more closely related to APNs from other lepidopterans than they are to each other. This report of three different aminopeptidases N in Helicoverpa punctigera adds support to a recent suggestion that at least one gene duplication has taken place in ancestral lepidopterans. The full sequences of the aminopeptidases are available at GENBANK with the following accession numbers: HpAPN1: AF217248, HpAPN2: AF217249, HpAPN3: AF217250.

Juvenile Fasciola hepatica are resistant to killing in vitro by free radicals compared with larvae of Schistosoma mansoni.

Free radicals have previously been shown to kill the immature stages of the trematode, Schistosoma mansoni but their effect on newly excysted juvenile (NEJ) flukes of Fasciola hepatica has not been established. Using acetaldehyde and xanthine oxidase to chemically generate reactive oxygen intermediates (ROI), up to 61% of NEJ were killed but only when exposed to high levels of ROI. At low concentrations of acetaldehyde and xanthine oxidase as sources of reactive oxygen intermediates, only 6-29% of NEJ were killed compared with 70-92% of schistosomula. Incubation with lipopolysaccharide (LPS)-stimulated rat peritoneal lavage cells (PLCs) killed only 7-15% of NEJ whereas 78-87% of schistosomula were killed under the same conditions by a mechanism dependent on the production of reactive nitrogen intermediates. Relative to immature and adult parasites, NEJ expressed 2.5-20-fold lower levels of superoxide dismutase and glutathione S-transferase but no catalase activity was detected. Incubation of NEJ with inhibitors of peroxidases and glutathione metabolism increased the mean killing of NEJ by LPS-stimulated rat PLCs to 40-75%. These results demonstrate that, in comparison to schistosomula of S. mansoni, NEJ of F. hepatica are relatively resistant to killing by free radicals and this resistance could, in part, be due to the activity of oxidant scavenger enzymes of NEJ.