Minimum inhibitory concentrations and disk diffusion zone diameter for selected antibiotics against streptococci isolated from bovine intramammary infections

The antimicrobial susceptibility to 11 antibiotics was determined of 358 streptococcal isolates representing six species was determined. All isolates were from milk samples obtained from clinical or subclinical cases of bovine mastitis. Agar disk diffusion zone diameters and minimum inhibitory concentrations were obtained for all isolates. Of the antibiotics tested that are available for mastitis therapy, cephalothin, penicillin, ampicillin, novobiocin, and erythromycin demonstrated acceptable activity against nonenterococcal streptococci, but only penicillin and ampicillin demonstrated moderate activity against Enterococcus faecalis. Enterococcus faecalis demonstrated substantial resistance to cephalothin, erythromycin, gentamicin, streptomycin, and tetracycline, while the nonenterococcal streptococci demonstrated substantial resistance to gentamicin, streptomycin, and tetracycline. Streptococcus uberis demonstrated greater antibiotic resistance than did Streptococcus dysgalactiae, while Aerococcus viridans demonstrated the greatest overall resistance of the nonenterococcal species.     

Pork quality from pigs fed on low glucosinate rapeseed meal: Influence of level in the diet,sex and ultimate pH

The appearance and eating quality of pork M. longissimus lumbrum from gilt and castrate pigs fed on diets containing a low glucosinate/low erucic acid rapeseed meal (cv. Tower) were assessed and compared with pork from pigs fed diets containing soya bean meal. At 90 kg liveweight, higher levels of either protein supplement, and therefore higher levels of dietary protein, gave slightly leaner meat. Meat from pigs fed rapeseed meal had more haem pigment and was slightly darker and redder than that from soya bean fed pigs. Differences in the quality of pork from the low glucosinate rapeseed meal and soya bean diets were small. Ratings for texture, juiciness and flavour of the lean varied little between the treatment groups. Suggestions that rapeseed meal as a protein supplement in diets might lead to inferior quality meat were not substantiated. The ultimate pH varied from 5.3 to 7.1 independently of the treatments and provided, for the first time, definitive relationships between pH and eating quality. Toughness and flavour were maximum and juiciness was a minimum after roasting meat of about pH 5.9. The ultimate pH had a larger effect on organoleptic quality than either sex or level of dietary inclusion of rapeseed or soya bean meals.     

Factors affecting the radical scavenging activity of polyaniline

Polyaniline was chemically synthesized by oxidizing aniline with ammonium persulfate with and without hydrochloric acid (G-PANI and NR-PANI, respectively). NR-PANI and G-PANI were dedoped with ammonium hydroxide to yield NR-PANIdd and G-PANIdd. SEM images revealed a typical granular morphology for G-PANI and G-PANIdd, while NR-PANI, formed using a ‘falling pH method’, and NR-PANIdd, consisted of micro/nanorods and flakes. The samples were characterized using FTIR and the level of oxidation was determined by X-ray photoelectron spectroscopy (XPS). The surface area of the samples was measured by the BET method. The free radical scavenging activity, using the DPPH assay, showed the following ranking: NR-PANI > G-PANI ≈ NR-PANIdd > G-PANIdd. The radical scavenging activity of the polyanilines did not correlate with conductivity or surface area measurements, but was critically dependent upon the level of oxidation, and higher activity was obtained with the more reduced polyaniline samples.     

Isolation, amino acid sequence and biological activities of novel long-chain polyamine-associated peptide toxins from the sponge Axinyssa aculeata

A novel family of functionalized peptide toxins, aculeines (ACUs), was isolated from the marine sponge Axinyssa aculeate. ACUs are polypeptides with N-terminal residues that are modified by the addition of long-chain polyamines (LCPA). Aculeines were present in the sponge extract as a complex mixture with differing polyamine chain lengths and peptide structures. ACU-A and B, which were purified in this study, share a common polypeptide chain but differ in their N-terminal residue modifications. The amino acid sequence of the polypeptide portion of ACU-A and B was deduced from 3' and 5' RACE, and supported by Edman degradation and mass spectral analysis of peptide fragments. ACU induced convulsions upon intracerebroventricular (i.c.v.) injection in mice, and disrupted neuronal membrane integrity in electrophysiological assays. ACU also lysed erythrocytes with a potency that differed between animal species. Here we describe the isolation, amino acid sequence, and biological activity of this new group of cytotoxic sponge peptides.     

Borate-catalyzed carbon dioxide hydration via the carbonic anhydrase mechanism

The hydration of CO(2) plays a critical role in carbon capture and geoengineering technologies currently under development to mitigate anthropogenic global warming and in environmental processes such as ocean acidification. Here we reveal that borate catalyzes the conversion of CO(2) to HCO(3)(-) via the same fundamental mechanism as the enzyme carbonic anhydrase, which is responsible for CO(2) hydration in the human body. In this mechanism the tetrahydroxyborate ion, B(OH)(4)(-), is the active form of boron that undergoes direct reaction with CO(2). In addition to being able to accelerate CO(2) hydration in alkaline solvents used for carbon capture, we hypothesize that this mechanism controls CO(2) uptake by certain saline bodies of water, such as Mono Lake (California), where previously inexplicable influx rates of inorganic carbon have created unique chemistry. The new understanding of CO(2) hydration provided here should lead to improved models for the carbon cycle in highly saline bodies of water and to advances in carbon capture and geoengineering technology.