Anaerobic degradation of dimethylsulfoniopropionate to 3-S-methylmercaptopropionate by a marine Desulfobacterium strain

Dimethylsulfoniopropionate, an osmolyte of marine algae, is thought to be the major precursor of dimethyl sulfide, which plays a dominant role in biogenic sulfur emission. The marine sulfate-reducing bacterium Desulfobacterium strain PM4 was found to degrade dimethylsulfoniopropionate to 3-S-methylmercaptopropionate. The oxidation of one of the methyl groups of dimethylsulfoniopropionate was coupled to the reduction of sulfate; this process is similar to the degradation of betaine to dimethylglycine which was described earlier for the same strain. Desulfobacterium PM4 is the first example of an anaerobic marine bacterium that is able to demethylate dimethylsulfoniopropionate.

Deterministic model to evaluate the impact of lactational treatment of subclinical mastitis due to coagulase-negative staphylococci

Coagulase-negative staphylococci (CNS) are the most frequently isolated bacteria from milk samples in several studies worldwide. Despite their relative frequency, specific measures aiming at their control are not well established. One possible measure to include in a control programme is lactational antimicrobial treatment. The decision to perform such treatment, as well as other actions on farm, should be based on the likelihood of financial return. A deterministic model was used to evaluate whether performing an antimicrobial treatment during the lactation for quarters infected with CNS was financially justifiable. Input variables for the impact of CNS on udder health were based on a previous study by the same authors and on available literature on the subject. Prices included in the model were based on 2009/2010 conditions in Portugal. The average result per antimicrobial treated quarter was a net loss of (sic)38.74. Performing a sensitivity analysis to evaluate how systematic variation of the input variables of the model would lead to outcome changes showed that variation in input variables nearly always led to a negative outcome, with the greatest variation in losses observed for variation in the length of treatment and milk withdrawal period (-(sic)46.26 to -(sic)28.49). The situations in which a net benefit was to be expected included the bulk tank somatic cell count decreasing to a level corresponding to a premium payment or to penalties being avoided, and the prevention of transmission of CNS in the milking parlour when the possibility of transmission was at its highest level. For most situations, lactational treatment of CNS subclinical mastitis was not financially justifiable

On a number theoretic property of optimal maintenance grouping

In this paper we consider the problem of preventive maintenance of a failure prone system, for which a number of maintenance actions has to be executed on a regular basis. For each action i the frequency is prescribed. Between consecutive actions of type i there is an integer interspacing of T(i) time units. The set-up costs are activity dependent. The set-up structure is supposed to be tree-like and additive over the set-up nodes involved in the action or group of actions. Hence, for different activities with common setup nodes joint execution leads to set-up costs reduction. The question is how the actions should be arranged in time in order to exploit this set-up costs reduction effect maximally. It is shown that the time averaged set-up costs are minimal if a main peak clustering property is satisfied: all maintenance actions are combined at one moment in time. Intuitively, this property is appealing, but it asks for some interesting and non-trivial applications of number theory and inductive reasoning, to prove it

AN ANALYTICAL FRAMEWORK FOR DISCUSSING FARM BUSINESS INTERRUPTION INSURANCE FOR CLASSICAL SWINE FEVER

This paper studies farm business interruption insurance for Classical Swine Fever epidemics. Insight into the size of risk is obtained by a very detailed Monte-Carlo simulation model that includes both epidemiological and economic factors. The paper also considers issues such as farmers' and governments' influence on the size of risk.Livestock Production/Industries, Risk and Uncertainty,

The Steroid Catabolic Pathway of the Intracellular Pathogen Rhodococcus equi Is Important for Pathogenesis and a Target for Vaccine Development

Rhodococcus equi causes fatal pyogranulomatous pneumonia in foals and immunocompromised animals and humans. Despite its importance, there is currently no effective vaccine against the disease. The actinobacteria R. equi and the human pathogen Mycobacterium tuberculosis are related, and both cause pulmonary diseases. Recently, we have shown that essential steps in the cholesterol catabolic pathway are involved in the pathogenicity of M. tuberculosis. Bioinformatic analysis revealed the presence of a similar cholesterol catabolic gene cluster in R. equi. Orthologs of predicted M. tuberculosis virulence genes located within this cluster, i.e. ipdA (rv3551), ipdB (rv3552), fadA6 and fadE30, were identified in R. equi RE1 and inactivated. The ipdA and ipdB genes of R. equi RE1 appear to constitute the α-subunit and β-subunit, respectively, of a heterodimeric coenzyme A transferase. Mutant strains RE1ΔipdAB and RE1ΔfadE30, but not RE1ΔfadA6, were impaired in growth on the steroid catabolic pathway intermediates 4-androstene-3,17-dione (AD) and 3aα-H-4α(3′-propionic acid)-5α-hydroxy-7aβ-methylhexahydro-1-indanone (5α-hydroxy-methylhexahydro-1-indanone propionate; 5OH-HIP). Interestingly, RE1ΔipdAB and RE1ΔfadE30, but not RE1ΔfadA6, also displayed an attenuated phenotype in a macrophage infection assay. Gene products important for growth on 5OH-HIP, as part of the steroid catabolic pathway, thus appear to act as factors involved in the pathogenicity of R. equi. Challenge experiments showed that RE1ΔipdAB could be safely administered intratracheally to 2 to 5 week-old foals and oral immunization of foals even elicited a substantial protective immunity against a virulent R. equi strain. Our data show that genes involved in steroid catabolism are promising targets for the development of a live-attenuated vaccine against R. equi infections

Seminar Managemetn-Informatiesystemen in de varkenshouderij

Dinsdag 25 augustus 1992 presenteerden Prof. R.S. Morris en Prof. V.R. Eidman in Rosmalen hun visie over de mogelijkheden die management-informatiesystemen kunnen bieden om de bedrijfsvoering op varkensbedrijven te ondersteune

Synthesis and characterization of sialylated lactose- and lactulose-derived oligosaccharides by Trypanosoma cruzi trans-sialidase

Sialylated oligosaccharides contribute 12.6-21.9 % of total free oligosaccharides in human milk (hMOS). These acidic hMOS possess prebiotic properties and display anti-adhesive effects against pathogenic bacteria. Only limited amounts of sialylated hMOS are currently available. The aim of our work is to enzymatically synthesize sialylated oligosaccharides mimicking hMOS functionality. In this study we tested mixtures of glucosylated-lactose (GL34), galactosylated-lactulose (LGOS) and galacto-oligosaccharide (Vivinal GOS) molecules, as trans-sialylation acceptor substrates. The recombinant trans-sialidase enzyme from Trypanosoma cruzi (TcTS) was used for enzymatic decoration, transferring (α2→3)-linked sialic acid from donor substrates to the non-reducing terminal β-galactopyranosyl units of these acceptor substrates. The GL34 F2 2-glc-lac compound with an accessible terminal galactosyl residue was sialylated efficiently (conversion degree of 47.6 %). TcTS also sialylated at least five LGOS structures and eleven Vivinal GOS DP3-4 compounds. These newly synthesized sialylated oligosaccharides are interesting as potential hMOS-mimics for applications in biomedical and functional food products