Identifying factors which maximise the lambing performance of hoggets: a cross sectional study

AIM: To identity perceptions of farmers with respect to advantages of hogget lambing and to identify optimal management strategies for hogget lambing used in New Zealand.

METHODS: A questionnaire was sent to 1,038 sheep farmers in New Zealand who had indicated their hoggets would be lambing in 2002. Information was gathered on the practice of hogget lambing in New Zealand, in particular on the numbers and breeds of hoggets and rams used, selection criteria used for hoggets, use of teasers (vasectomised rams), length of mating period, use of mating crayons, vaccinations, medications and mineral supplements given, level of feed offered, use of pregnancy scanning, management during pregnancy and lambing, number of lambs present at docking, and shearing policies for hoggets. Farmers were also asked to indicate the relative importance of five stated reasons for choosing to have their hoggets mated in 2002.

RESULTS: A total of 629 (60.6%) responses were incorporated in the analysis, and the average percentage of hogget lambing was 60%. Use of vaccinations, length of the mating period, number of rams used, breed of hogget, weight at mating, management during lactation, and shearing policy were associated (p<0.05) with the lambing performance of hoggets, in the multivariate analysis.

CONCLUSIONS: This study indicated that to ensure high lambing percentages (LP) in hoggets in New Zealand, sheep farmers should: vaccinate hoggets against toxoplasmosis and campylobacteriosis; utilise a 40-day mating period; use 2.6–3.5% of rams during mating; incorporate Finn or East Friesian genetics; ensure liveweights at mating are as high as possible; manage single- and multiple-bearing/-rearing hoggets separately during the lambing and lactation periods; and shear hoggets pre-mating.     

Common structure of soluble amyloid oligomers implies common mechanism of pathogenesis

Soluble oligomers are common to most amyloids and may represent the primary toxic species of amyloids, like the Abeta peptide in Alzheimer's disease (AD). Here we show that all of the soluble oligomers tested display a common conformation-dependent structure that is unique to soluble oligomers regardless of sequence. The in vitro toxicity of soluble oligomers is inhibited by oligomer-specific antibody. Soluble oligomers have a unique distribution in human AD brain that is distinct from fibrillar amyloid. These results indicate that different types of soluble amyloid oligomers have a common structure and suggest they share a common mechanism of toxicity.     

Fluid flow stimulates tissue plasminogen activator secretion by cultured human endothelial cells

Wall shear stress generated by blood flow may regulate the expression of fibrinolytic proteins by endothelial cells. Tissue plasminogen activator (tPA) and plasminogen activator inhibitor, type 1 (PAI-1) secretion by cultured human endothelial cells were not affected by exposure to venous shear stress (4 dynes/cm2). However, at arterial shear stresses of 15 and 25 dynes/cm2, the tPA secretion rate was 2.1 and 3.0 times greater, respectively, than the basal tPA secretion rate. PAI-1 secretion was unaffected by shear stress over the entire physiological range.     

A new cofactor in a prokaryotic enzyme: tryptophan tryptophylquinone as the redox prosthetic group in methylamine dehydrogenase

Methylamine dehydrogenase (MADH), an alpha 2 beta 2 enzyme from numerous methylotrophic soil bacteria, contains a novel quinonoid redox prosthetic group that is covalently bound to its small beta subunit through two amino acyl residues. A comparison of the amino acid sequence deduced from the gene sequence of the small subunit for the enzyme from Methylobacterium extorquens AM1 with the published amino acid sequence obtained by the Edman degradation method, allowed the identification of the amino acyl constituents of the cofactor as two tryptophyl residues. This information was crucial for interpreting 1H and 13C nuclear magnetic resonance, and mass spectral data collected for the semicarbazide- and carboxymethyl-derivatized bis(tripeptidyl)-cofactor of MADH from bacterium W3A1. The cofactor is composed of two cross-linked tryptophyl residues. Although there are many possible isomers, only one is consistent with all the data: The first tryptophyl residue in the peptide sequence exists as an indole-6,7-dione, and is attached at its 4 position to the 2 position of the second, otherwise unmodified, indole side group. Contrary to earlier reports, the cofactor of MADH is not 2,7,9-tricarboxypyrroloquinoline quinone (PQQ), a derivative thereof, or pro-PQQ. This appears to be the only example of two cross-linked, modified amino acyl residues having a functional role in the active site of an enzyme, in the absence of other cofactors or metal ions.