Island–matrix relationships in Nama Karoo inselberg landscapes Part II: Are some inselbergs better sources than others?

To answer the question whether some inselbergs are better sources thanothers, thus potentially affecting processes in inselberg landscapes,inselberg-matrix affinities and the influence of regional physicalenvironmental parameters (latitude, longitude, distance from coast andmainland)and parameters operating on landscape level (elevation and geology) wereinvestigated. All investigated environmental parameters affected the observedpatternsto some extend. Distance from mainland and geographic position were importantona regional level, while elevation only influenced the observed trends wheninvestigated at a local level. Parameters determining bettersources within the selected study areas and sites, here simply definedasshowing higher floristic affinities with the surrounding, appeared to beinselbergs: (a) in southern Namibia and thus in an inland position; (b) at adistancefrom other mountainous habitats; and (c) of low elevation. Although theimportanceof inselbergs for conservation and maintenanceof biodiversity is evident, this study points towards a complex situation,ruling out the sole effect of any one of the parameters investigated atregionaland landscape level. Further observations and analysis at a local level maygivesome pointers and assist in identifying critical aspects important forconservation and range management.     

Anaerobic degradation of n-hexane in a denitrifying bacterium: Further degradation of the initial intermediate (1-methylpentyl)succinate via C-skeleton rearrangement

The anaerobic degradation pathway of the saturated hydrocarbon n-hexane in a denitrifying strain (HxN1) was examined by gas chromatography-mass spectrometry of derivatized extracts from cultures grown with unlabeled and deuterated substrate; several authentic standard compounds were included for comparison. The study was focused on possible reaction steps that follow the initial formation of (1-methylpentyl)succinate from n-hexane and fumarate. 4-Methyloctanoic, 4-methyloct-2-enoic, 2-methylhexanoic, 2-methylhex-2-enoic and 3-hydroxy-2-methylhexanoic acids (in addition to a few other methyl-branched acids) were detected in n-hexane-grown but not in n-hexanoate-grown cultures. Labeling indicated preservation of the original carbon chain of n-hexane in these acids. Tracing of the deuterium label of 3- d1-(1-methylpentyl)succinate in tentative subsequent products indicated a deuterium/carboxyl carbon exchange in the succinate moiety. This suggests that the metabolism of (1-methylpentyl)succinate employs reactions analogous to those in the established conversion of succinyl-CoA via methylmalonyl-CoA to propionyl-CoA. Accordingly, a pathway is proposed in which (1-methylpentyl)succinate is converted to the CoA-thioester, rearranged to (2-methylhexyl)malonyl-CoA and decarboxylated (perhaps by a transcarboxylase) to 4-methyloctanoyl-CoA. The other identified fatty acids match with a further degradation of 4-methyloctanoyl-CoA via rounds of conventional beta-oxidation. Such a pathway would also allow regeneration of fumarate (for n-hexane activation) from propionyl-CoA formed as intermediate and hence present a cyclic process.     

Epizootiologic and ecologic investigations of European brown hares (Lepus europaeus) in selected populations from Schleswig-Holstein, Germany

From 1997-99 European brown hare (Lepus europaeus) population densities were estimated by spotlight surveys within different areas in Schleswig-Holstein, Germany. These areas showed a wide variation in local hare population densities. In addition, red fox (Vulpes vulpes) densities were estimated in 1997 by surveys of fox dens and litters. Sera of 321 hares (shot between 1998-2000) from four study areas were examined for antibodies against European brown hare syndrome virus (EBHSV) by enzyme linked immunosorbent assay (ELISA), Yersinia spp. (n = 299) and Francisella tularensis (n = 299) by western blotting, Brucella spp. by Rose Bengal test, and Toxoplasma gondii by Sabin-Feldman test (n = 318). Tissue samples comprising lung, liver, spleen, kidney, heart, and adrenal glands were collected for histopathology. Liver (n = 201) and spleen (n = 201) samples were processed for the detection of T. gondii-antigen in tissue sections and 321 liver and spleen samples were investigated for EBHSV-antigen by ELISA. Furthermore, 116 hares were examined macro- and microscopically for lungworms. Significant negative correlations between hare and fox densities were found in spring and autumn 1997. Antibodies against EBHSV were detected in 92 of 321 (29%), against Yersinia spp. in 163 of 299 (55%), and against T. gondii in 147 of 318 (46%) hares. We evaluated the potential influence of origin and hunting season on exposure rates of hares using logistic regression analysis. A strong association between hare densities and exposure rates was observed for various agents. One hundred and eight of 201 (57%) hares were positive for T. gondii-antigen. All sera were negative for antibodies against Brucella spp. and F. tularensis and all lung samples were negative for lungworms. In conclusion, variation in red fox densities may have an impact on the hare populations examined and the infectious diseases we studied seem to play a subordinate role in the dynamics of European brown hare populations from Schleswig-Holstein.     

Quantitative analysis of dipeptidyl peptidase inhibitor P32/98 and its main metabolite in rat, dog, mouse, monkey, human plasma and human urine using liquid chromatography-tandem mass spectrometry: application to pharmacokinetic evaluation

A sensitive, specific and robust assay was developed for the simultaneous determination of the oral antidiabetic drug candidate P32/98 and its main metabolite P57/99 in different biological fluids using LC-MS/MS in the atmospheric pressure chemical ionization (APCI) positive mode. Both analytes were isolated from the biological matrices by solid phase extraction using a strong cation exchanger. This assay was successfully cross-validated for rat, dog, mouse, monkey, human plasma and human urine. The pre-study validation results, as well as the in-study quality control (QC) data obtained, demonstrate the feasibility of the assay for pharmacokinetic evaluation of the compounds in different species and confirm the robustness of the assay for routine use.     

A novel method for the determination of carbonyl groups in cellulosics by fluorescence labeling. 3. Monitoring oxidative processes

The fluorescence-based CCOA method for determination of carbonyl group profiles in cellulosic substrates was employed to study the mechanisms of various oxidative and degradation processes involving celluloses in greater detail. The approach comprises labeling with the marker carbazole-9-carboxylic acid [2-(2-aminooxyethoxy)ethoxy]amide (CCOA), followed by gel permeation chromatography in DMAc/LiCl with fluorescence, multiangle laser light scattering, and refractive index detection. At first, the CCOA method was applied to study solutions of pulp in N-methylmorpholine-N-oxide monohydrate (NMMO), as occurring in the production of Lyocell-type fibers. NMMO is a rather strong oxidant that on one hand converts reducing end groups to carboxyl structures, thus lowering the overall carbonyl content, but generates new keto structures along the chain by nonselective oxidation on the other hand. The CCOA method allowed for the first time to distinguish the carbonyl course in different molecular weight ranges. Second, alkalization and aging of pulp, which are used in the industrial preparation of cellulose derivatives, e.g., as an element of the preripening process in viscose rayon production, were investigated. The CCOA method shows a clear reduction of the molecular weight, accompanied by a fast loss of carbonyls in the first phase, which is due to removal of low-molecular weight material by dissolution, and a slow decrease in the second phase, which is caused by further oxidation of carbonyl groups. Also here, differences in the carbonyl course in different molecular weight regions were monitored. Third, electron beaming, proposed as a means of pulp activation, was shown to decrease and narrow the molecular weight distribution, under generation of comparatively low amounts of carbonyls, which, however, are also introduced into high molecular weight, crystalline domains, as shown by a comparison of homogeneous and heterogeneous CCOA labeling approach. Finally, as the fourth application, thermal treatment of cellulose at temperatures between 105 and 165 degrees C was shown to bring about a small reduction of the molecular weight, which only at higher drying temperatures is accompanied by an introduction of carbonyls over the whole molecular weight range.     

Heterogeneity of CD4 and CD8+ memory T cells in localized and generalized Wegener's granulomatosis

Memory T cells display phenotypic heterogeneity. Surface antigens previously regarded as exclusive markers of naive T cells, such as L-selectin (CD62L), can also be detected on some memory T cells. Moreover, a fraction of CD45RO+ (positive for the short human isoform of CD45) memory T cells reverts to the CD45RA+ (positive for the long human isoform of CD45) phenotype. We analyzed patients with biopsy-proven localized Wegener's granulomatosis (WG) (n = 5), generalized WG (n = 16) and age- and sex-matched healthy controls (n = 13) to further characterize memory T cells in WG. The cell-surface expression of CD45RO, CD45RA, CD62L, CCR3, CCR5 and CXCR3 was determined on blood-derived T cells by four-color flow cytometric analysis. The fractions of CCR5+ and CCR3+ cells within the CD4+CD45RO+ and CD8+CD45RO+ memory T cell populations were significantly expanded in localized and generalized WG. The mean percentage of Th1-type CCR5 expression was higher in localized WG. Upregulated CCR5 and CCR3 expression could also be detected on a fraction of CD45RA+ T cells. CD62L expression was seen on approximately half of the memory T cell populations expressing chemokine receptors. This study demonstrates for the first time that expression of the inducible inflammatory chemokine receptors CCR5 and CCR3 on CD45RO+ memory T cells, as well as on CD45RA+ T cells ('revertants'), contributes to phenotypic heterogeneity in an autoimmune disease, namely WG. Upregulated CCR5 and CCR3 expression suggests that the cells belong to the effector memory T cell population. CCR5 and CCR3 expression on CD4+ and CD8+ memory T cells indicates a potential to respond to chemotactic gradients and might be important in T cell migration contributing to granuloma formation and vasculitis in WG.     

Hybrid embryonic stem cell-derived tetraploid mice show apparently normal morphological,physiological, and neurological characteristics

ES cell-tetraploid (ES) mice are completely derived from embryonic stem cells and can be obtained at high efficiency upon injection of hybrid ES cells into tetraploid blastocysts. This method allows the immediate generation of targeted mouse mutants from genetically modified ES cell clones, in contrast to the standard protocol, which involves the production of chimeras and several breeding steps. To provide a baseline for the analysis of ES mouse mutants, we performed a phenotypic characterization of wild-type B6129S6F(1) ES mice in relation to controls of the same age, sex, and genotype raised from normal matings. The comparison of 90 morphological, physiological, and behavioral parameters revealed elevated body weight and hematocrit as the only major difference of ES mice, which exhibited an otherwise normal phenotype. We further demonstrate that ES mouse mutants can be produced from mutant hybrid ES cells and analyzed within a period of only 4 months. Thus, ES mouse technology is a valid research tool for rapidly elucidating gene function in vivo.     

A novel yeast U2 snRNP protein, Snu17p, is required for the first catalytic step of splicing and for progression of spliceosome assembly

We have isolated and microsequenced Snu17p, a novel yeast protein with a predicted molecular mass of 17 kDa that contains an RNA recognition motif. We demonstrate that Snu17p binds specifically to the U2 small nuclear ribonucleoprotein (snRNP) and that it is part of the spliceosome, since the pre-mRNA and the lariat-exon 2 are specifically coprecipitated with Snu17p. Although the SNU17 gene is not essential, its knockout leads to a slow-growth phenotype and to a pre-mRNA splicing defect in vivo. In addition, the first step of splicing is dramatically decreased in extracts prepared from the snu17 deletion (snu17Delta) mutant. This defect is efficiently reversed by the addition of recombinant Snu17p. To investigate the step of spliceosome assembly at which Snu17p acts, we have used nondenaturing gel electrophoresis. In Snu17p-deficient extracts, the spliceosome runs as a single slowly migrating complex. In wild-type extracts, usually at least two distinct complexes are observed: the prespliceosome, or B complex, containing the U2 but not the U1 snRNP, and the catalytically active spliceosome, or A complex, containing the U2, U6, and U5 snRNPs. Northern blot analysis and affinity purification of the snu17Delta spliceosome showed that it contains the U1, U2, U6, U5, and U4 snRNPs. The unexpected stabilization of the U1 snRNP and the lack of dissociation of the U4 snRNP suggest that loss of Snu17p inhibits the progression of spliceosome assembly prior to U1 snRNP release and after [U4/U6.U5] tri-snRNP addition.