Lymphokine production in mouse mixed lymphocyte reaction (MLR)

We have investigated alloantigen differences which stimulate lymphokine release and³H-TdR uptake in primary ‘one-way’ MLC among allogeneic mice. When mice differing at the wholeH-2 region were tested, MIF and immune IF release was observed, along with a marked³H-TdR uptake. Differences atK, D, orI-S-G regions stimulate both lymphokine release and³H-TdR uptake, though stronger immune IF and³H-TdR responses were observed with differences atI-S-G regions. On the other hand, when mice differing in their minor histocompatibility antigens, and notably at theMls locus, were tested, lymphokine release took place even in the absence of proliferation. Lastly, in MLC between mice differing at multiple minor loci, butH-2 andMls matched, MIF release only, and not immune IF and³H-TdR responses were observed in a few combinations. These findings show that T lymphocytes can recognize alloantigens by releasing lymphokines even without going through proliferation. Moreover, different levels of T-lymphocyte activation exist, depending on the kind of stimulating alloantigens present.     

Oral Mucosa Patch Test: A New Tool to Recognize and Study the Adverse Effects of Dietary Nickel Exposure

On contact with the skin, nickel may cause allergic contact dermatitis, which can be diagnosed by an epicutaneous patch test. Nickel exposure via the intestinal mucosa can induce diarrhea, abdominal pain, and swelling. The aim of the present study was to investigate the relationship between these symptoms and nickel intake by means of a novel oral mucosa patch test. Eighty-six patients with intestinal symptoms related to ingestion of nickel-containing foods were submitted to epicutaneous and oral mucosa patch tests for nickel. All patients with positive oral mucosa patch test results were subject to a low-nickel diet and monitored over time. Skin lesions were observed in 33 out of 86 (38.4%) patients evaluated by the epicutaneous patch test. Mucosal lesions were seen in 53 out of 86 (61.6%) patients given the oral mucosa patch test. After 2 months of a low-nickel diet, 52 out of 53 (98.1%) patients showed an improvement of their symptoms. There is a significant correlation between response time of the oral mucosa patch test and the latency of symptoms after ingestion of nickel-containing foods. Consequently, the oral mucosa patch test can be used to recognize and study the adverse effects of dietary nickel exposure that could be defined as allergic contact mucositis. A low-nickel diet is also shown to be an effective treatment for this condition.     

Wave and tidal flushing in a near-equatorial mesotidal atoll

Most of the atolls found worldwide are under microtidal regimes, and their circulation mechanisms are widely documented and well known. Here, we describe the flushing mechanisms of a small-sized mesotidal atoll, based on water-level, wave and current data obtained during two different periods (total of 60 d). Rocas is the only atoll in the South Atlantic Ocean and is built primarily of coralline algae. Two reef passages connect the atoll lagoon to the ocean. Synchronous current profilers were deployed at the two reef passages, one inside and one outside the atoll, to characterize the influence of tides and waves on the circulation. Results showed that wind waves drove a setup on the exposed side of the atoll and that currents were predominately downwind, causing outflow at both reef passages. Waves breaking on the windward side supplied water to the atoll causing the lagoon water level to rise above ocean water level, driving the outflow. However, unlike microtidal atolls, at Rocas Atoll the water level drops significantly below the reef rim during low tides. This causes the reef rim to act as a barrier to water pumping into the lagoon by waves, resulting in periodic activation of the wave pumping mechanism throughout a tidal cycle. As result, inflow occurs in the wider passage during 27% of each tidal cycle, starting at low tides and reversing direction during mid-flood tide when the water level exceeded approximately 1.6 m (while overtopping the atoll’s rim). Our findings show that tides play a direct role in driving circulation on a mesotidal atoll, not only by modulating wave setup but also by determining the duration of wave pumping into the lagoon.

     

Amphibian road mortality in Europe: a meta-analysis with new data from Poland

While the increasing vehicular traffic is widely suspected to play a role in the worldwide amphibian population decline, the research of amphibian road mortality is scarce, fragmented, fraught with methodological problems, and largely inconclusive. As the first attempt at a synthesis, we analyzed all available data on amphibian mortality in Europe and combined them with four previously unpublished surveys conducted by us. Based on our recalculation of road-kill counts in terms of species-specific road-kill recordability, we conclude that, in lowland Central Europe, the common toads, Bufo bufo, are the most common victims of vehicular traffic in suburban landscapes, while the common frogs, Rana temporaria and Triturus newts, prevail in rural landscapes. The green frogs also tend to be more frequent in rural areas. Common tree frogs, Hyla arborea, are unexpectedly rare in the road-kill record despite their terrestrial and migratory habits. In consideration of problems with obtaining accurate amphibian population estimates, we further propose the road kills-to-spawners ratio (R/S) as a working measure of the impact of road mortality on a local population. While the R/S ratio may not reflect the losses to an entire local amphibian population, it is free of the errors of whole-population estimates, which are notoriously difficult for amphibians. When corrected for species-specific road-kill recordability, most results suggest that the impact of roads on newts may have been underestimated and that the impact on common frog populations may be higher than on those of common toads. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users. Communicated by H. Kierdorf     

D-amino Acid Oxidase as an Industrial Biocatalyst

Biocatalysis driven by D-amino acid oxidase is a significant example of the commercial production of high value-added intermediates using enzyme-based technology. The results of the most recent research on this FAD-dependent catalyst are reported here. In particular, insight is given of how in the past few years the main industrial application of this enzyme, i.e. the stereospecific bioconversion of cephalosporin C to glutaryl-7-amino cephalosporanic acid in the two-step production of 7-amino cephalosporanic acid, has been implemented by improving its production and by engineering of the biocatalyst. The set-up and the optimization of different conditions for carrying out the process under different procedures have also been updated.     

Overexpression of a recombinant wild-type and His-tagged Bacillus subtilis glycine oxidase in Escherichia coli.

We have cloned the gene coding for the Bacillus subtilis glycine oxidase (GO), a new flavoprotein that oxidizes glycine and sarcosine to the corresponding alpha-keto acid, ammonia and hydrogen peroxide. By inserting the DNA encoding for GO into the multiple cloning site of the expression vector pT7.7 we produced a recombinant plasmid (pT7-GO). The pT7-GO encodes a fully active fusion protein with six additional residues at the N-terminus of GO (MARIRA). In BL21(DE3)pLysS Escherichia coli cells, and under optimal isopropyl thio-beta-D-galactoside induction conditions, soluble and active chimeric GO was expressed up to 1.14 U g(-1) of cell (and a fermentation yield of 3.82 U x L(-1) of fermentation broth). An N-terminal His-tagged protein (HisGO) was also successfully expressed in E. coli as a soluble protein and a fully active holoenzyme. HisGO represents approximately 3.9% of the total soluble protein content of the cell. The His-tagged GO was purified in a single step by nickel-chelate chromatography to a specific activity of 1.06 U x mg(-1) protein at 25 degrees C and with a yield of 98%. The characterization of the purified enzyme showed that GO is a homotetramer of approximately 180 kDa with the spectral properties typical of flavoproteins. GO exhibits good thermal stability, with a Tm of 46 degrees C after 30 min incubation; its stability is maximal in the 7.0-8.5 pH range. A comparison of amino-acid sequence and substrate specificity indicates that GO has similarities to other flavoenzymes acting on primary amines and on D-amino acids.     

D-amino Acid Oxidase as an Industrial Biocatalyst

Biocatalysis driven by D-amino acid oxidase is a significant example of the commercial production of high value-added intermediates using enzyme-based technology. The results of the most recent research on this FAD-dependent catalyst are reported here. In particular, insight is given of how in the past few years the main industrial application of this enzyme, i.e. the stereospecific bioconversion of cephalosporin C to glutaryl-7-amino cephalosporanic acid in the two-step production of 7-amino cephalosporanic acid, has been implemented by improving its production and by engineering of the biocatalyst. The set-up and the optimization of different conditions for carrying out the process under different procedures have also been updated.