Quantification of cytosol and membrane proteins in rumen epithelium of sheep with low or high CH4 emission phenotype.

BACKGROUND: Ruminant livestock are a major contributor to Australian agricultural sector carbon emissions. Variation in methane (CH4) produced from enteric microbial fermentation of feed in the reticulo-rumen of sheep differs with different digestive functions. METHOD: We isolated rumen epithelium enzymatically to extract membrane and cytosol proteins from sheep with high (H) and low (L) CH4 emission. Protein abundance was quantified using SWATH-mass spectrometry. RESULTS: The research found differences related to the metabolism of glucose, lactate and processes of cell defence against microbes in sheep from each phenotype. Enzymes in the methylglyoxal pathway, a side path of glycolysis, resulting in D-lactate production, differed in abundance. In the H CH4 rumen epithelium the enzyme hydroxyacylglutathione hydrolase (HAGH) was 2.56 fold higher in abundance, whereas in the L CH4 epithelium lactate dehydrogenase D (LDHD) was 1.93 fold higher. Malic enzyme 1 which converts D-lactate to pyruvate via the tricarboxylic cycle was 1.57 fold higher in the L CH4 phenotype. Other proteins that are known to regulate cell defence against microbes had differential abundance in the epithelium of each phenotype. CONCLUSION: Differences in the abundance of enzymes involved in the metabolism of glucose were associated with H and L CH4 phenotype sheep. Potentially this represents an opportunity to use protein markers in the rumen epithelium to select low CH4 emitting sheep.

Serum apolipoproteins A and B, lecithin: cholesterol acyl transferase activities and urinary cholesterol levels in nephrotic syndrome patients before and during steroid treatment.

Serum apolipoproteins A (Apo-A) and B (Apo-B) and lecithin: cholesterol acyl transferase (LCAT) activities and 24-hour urinary cholesterol levels were estimated in 25 nephrotic children before and during steroid treatment with 4 weeks of daily prednisolone followed by another 4 weeks of alternate-day prednisolone. The patients with untreated nephrotic syndrome (NS) showed significant decrease in serum Apo-A and LCAT activities associated with significant increase in serum Apo-B and urinary cholesterol levels compared to healthy controls (n = 25). Serum Apo-A levels correlated directly and Apo-B levels inversely with the serum albumin concentrations. After a transient elevation, the serum Apo-A level returned to control range by 8 weeks of treatment accompanied by a gradual increase in serum LCAT activity and decrease in urinary cholesterol excretion. Though, the serum Apo-B level was decreased with treatment, it was still significantly high compared to the controls.