Archaeal lipids in Mediterranean cold seeps: molecular proxies for anaerobic methane oxidation

We investigated the distributions and 13C values of biomarkers for Archaea associated with anaerobic methane oxidation in disparate settings throughout two Eastern Mediterranean mud dome fields. All major classes of archaeal lipids are present in the studied sediments, including isoprenoid glycerol diethers, isoprenoid glycerol dialkyl glycerol tetraethers, and irregular isoprenoid hydrocarbons. Of the compounds present, many, including a novel glycerol tetraether and sn-3-hydroxyarchaeol, have not been previously reported for settings in which methane oxidation is presumed to occur. Archaeal lipids are depleted in 13C, indicating that the Archaea from which they derive are either directly or indirectly involved with methane consumption. The most widespread archaeal lipids are archaeol, PMI, and glycerol tetraethers, and these compounds are present at all active sites. However, archaeal lipid abundances and distributions are highly variable; ratios of crocetane, PMI, and hydroxyarchaeol relative to archaeol vary from 0 to 6.5, from 0 to 2, and from 0 to 1, respectively. These results suggest that archaeal communities differ amongst the sites examined. In addition, carbon isotopic variability amongst archaeal biomarkers in a given mud breccia can be as large as 24 , suggesting that even at single sites multiple archaeal species perform or are supported by anaerobic methane oxidation

The herpes simplex virus type 1 UL37 gene product is a component of virus particles

The herpes simplex virus type 1 UL37 gene encodes a protein with an Mr of 120K that is produced at late times after infection. To study the properties of this protein we have linked a 10 amino acid epitope derived from a human cytomegalovirus protein to the UL37 polypeptide coding sequences by inserting an oligonucleotide at a SpeI site that is unique in the virus genome and lies close to the 3' end of the open reading frame. From studies on the resultant virus recombinant using a monoclonal antibody that recognizes the inserted epitope we find that, contrary to a previous report, the UL37 protein is a structural component of both virions and L particles and is present in the tegument of virus particles. Indirect immunofluorescence analysis revealed that the protein is distributed throughout infected cells but is more abundant in the cytoplasm than the nucleus

Short‐cut method for the calculation of sterilization conditions yielding optimum quality retention for conduction‐type heating of packaged foods

Based on analytical equations for the temperature distribution history in a container, the relation between the reductions of the concentrations of heat labile food components, including microorganisms. nutrients and sensory factors, and the kinetic parameters of the reactions causing these reductions, has been calculated numerically. For a constant temperature of the heating medium with time it is concluded that the loss of quality is almost minimal at one Fourier value of the heating time. This optimal Fourier value is a function of only the Biot number and the relationship between initial product temperature, cooling water temperature and retort temperature. At an infinite value of Biot and a cooling water temperature equal to the initial product temperature the optimum Fourier value amounts to 0.5. On the basis of this conclusion a short‐cut calculation method is developed. The method is valid for Biot numbers larger than 10, initial homogeneous product temperatures equal to or larger than the temperature of the cooling medium and for the main container geometries including spheres, cylinders and rectangular bodies. The method does not require tedious interpolations of tables. The calculation of the optimum process conditions to obtain the desired sterility and the calculation of the retention of the quality factor of interest require only a few minutes on a pocket calculator. For routine calculations the procedure can conveniently be programmed

Vaccination of MDA positive pigs with a live modified PRRSV vaccine

Since it emerged, PRRSV has had an important economic impact on the swine industry. Proper vaccination against PRRSV can significantly improve the production results in feeder finishing pigs. Ideally, fattening pigs are vaccinated at 6 weeks of age, when no maternally derived antibodies (MDA) are present anymore. However, when there is a high PRRSV wild-type pressure, it might be beneficial to vaccinate earlier. In this study, we investigated how antibodies influence vaccination with a modified PRRSV vaccine. To examine the effect of antibodies on the vaccine take, four groups of approximately 50 pigs each were vaccinated at 3 to 4 weeks of age with Porcilis PRRS (Intervet Int. b.v., Boxmeer, The Netherlands). At this period, various levels of PRRSV specific antibody titres were found. One group was vaccinated intradermally with 1 dose of Porcilis PRRS and 3 groups were vaccinated intramuscularly with 0.1, 1 and 10 doses of Porcilis PRRS, respectively. One group of 10 pigs was left unvaccinated. Blood was taken at various weeks post vaccination. PRRSV specific immunofluorescence test (IFT) antibody titres were determined from all samples and PRRSV neutralising antibody titres only from the samples taken at vaccination. Based on these data, it could be determined whether or not a pig seroconverted by vaccination and whether the vaccine had taken or not. To determine the effect of the antibody titres on vaccine take, all pigs were categorised according to their overall MDA titre and their PRRSV neutralising antibody titre at vaccination. Then the percentage of seroconverted animals per category was calculated. Regardless of the dose and route, 65% or more of the pigs seroconverted by vaccination, a percentage high enough to give sufficient herd protection. No consistent relation could be found between the virus neutralising (VN)-titres and the percentages of takes. When the effect of the total antibody titre on vaccine take was evaluated, high MDA titres were correlated with a high percentage of takes. At medium titres, the least number of takes were found. When the titres further decreased the percentage of takes again increased. We interpreted that these parabolic curves were the resultant of the positive effects of the opsonising PRRSV specific antibodies and the negative effects of PRRSV neutralising antibodies on vaccine take. Basically the virus can use two independent routes to enter its target cell, the macrophage. First, it can use the PRRSV specific receptor. Alternatively, in the presence of PRRSV specific antibodies, it can enter by the Fc-receptors on the macrophage. However, the influence of antibodies is opposite in both routes: high antibody levels will facilitate a better uptake of the virus by the Fc-receptors but will inhibit the uptake of the virus in the macrophage by the PRRSV specific receptors. At low antibody titres, the reverse situation occurs: virus uptake by the receptors is enhanced and uptake by the Fc-receptors is minimised. With this mechanism, the lowest percentage of takes will be obtained at medium antibody titres. High percentages of takes will be found at either high antibody titres, facilitating a good uptake by the Fc-receptor, or at low antibody titres, facilitating a good uptake by the PRRSV specific receptor. Because of the opsonisation of the virus by PRRSV specific antibodies, it will be possible to vaccinate young, MDA positive piglets

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