Convergent evolution in feeding types: salivary gland mass differences in wild ruminant species

In the ongoing debate about divergent evolutionary morphophysiological adaptations of grazing and browsing ruminants, the size of the salivary glands has received special attention. Here, we report the most comprehensive dataset on ruminant salivary glands so far, with data on the Glandula parotis (n=62 species), Gl. mandibularis (n=61), Gl. buccalis ventralis (n=44), and Gl. sublingualis (n=30). All four salivary gland complexes showed allometric scaling with body mass (BM); in all cases, the 95% confidence interval for the allometric exponent included 0.75 but did not include 1.0 (linearity); therefore, like other parameters linked to the process of food intake, salivary gland mass appears to be correlated to metabolic body weight (BM0.75), and comparisons of relative salivary gland mass between species should rather be made on the basis of BM0.75 than as a percentage of BM. In the subsequent analyses, the percentage of grass (%grass) in the natural diet was used to characterize the feeding type; the phylogenetic tree used for a controlled statistical evaluation was entirely based on mitochondrial DNA information. Regardless of phylogenetic control in the statistical treatment, there was, for all four gland complexes, a significant positive correlation of BM and gland mass, and a significant negative correlation between %grass in the natural diet and gland mass. If the Gl. parotis was analyzed either for cervid or for bovid species only, the negative correlation of gland mass and %grass was still significant in either case; an inspection of certain ruminant subfamilies, however, suggested that a convergent evolutionary adaptation can only be demonstrated if a sufficient variety of ruminant subfamilies are included in a dataset. The results support the concept that ruminant species that ingest more grass have smaller salivary glands, possibly indicating a reduced requirement for the production of salivary tannin-binding proteins.     

Kinetic Modeling of Amino Acid Oxidation Catalyzed by a New D‐Amino Acid Oxidase from Arthrobacter protophormiae

Amino acid oxidases, which enantiospecifically catalyze the oxidative deamination of either D‐ or L‐amino acids, belong to the class of oxidoreductases functioning with a tightly bound cofactor. This cofactor favors industrial applications of D‐amino acid oxidases (D‐AAO). Hence, the enzyme is very important for the industrial application in the purification and determination of certain amino acids. In developing the enzyme‐catalyzed reaction for large‐scale production, modeling of the reaction kinetics plays an important role. Therefore, the subject of this study was the kinetics of the oxidative deamination, a very complex reaction system, which is catalyzed by D‐AAO from Arthrobacter protophormiae using its natural substrate D‐methionine and the aromatic amino acid 3,4‐dihydroxyphenyl‐D‐alanine (D‐DOPA). The kinetic parameters determined by the measurement of the initial rate and nonlinear regression were verified in batch reactor experiments by comparing calculated and experimental concentration‐time curves. It was found that the enzyme is highly specific towards D‐methionine (K_m = 0.24 mM) and not as specific to D‐DOPA as a substrate (K_m = 9.33 mM). The enzyme activity towards D‐methionine ( = 3.01 U/mL) was approx. seven times higher than towards D‐DOPA ( = 20.01 U/mL). The enzyme exhibited no activity towards L‐methionine and L‐DOPA. Batch and repetitive batch experiments were performed with both substrates in the presence and in the absence of catalase for hydrogen peroxide decomposition. Their comparison made it possible to conclude that hydrogen peroxide has no negative influence on the enzyme activity.     

DESCRIPTION OF THE SENSORY CHARACTERISTICS OF SPANISH UNIFLORAL HONEYS BY FREE CHOICE PROFILING

Different Spanish unifloral honeys (eucalyptus, sunflower, rosemary, thyme, lavender, citrus, anise, quercus, and lemon blossom) and one multifloral honey were studied by Free-Choice Profiling (FCP) analysis. Generalized Procrustes Analysis (GPA) applied to the FCP data allowed discrimination between samples and provided information on the attributes responsible for the differences observed. The honeys had significantly different sensory characteristics. Textural attributes were the predominant factor in discriminating between samples, and appearance (color included) was also correlated with GPA dimensions to a lesser extent.     

Reproductive ecology of Rhododendron ponticum (Ericaceae) in relict Mediterranean populations

In the southern Iberian Peninsula, Rhododendron ponticum occurs in restricted and vulnerable populations as a Tertiary relict. Population structure and the main phases of the reproductive process were examined in order to shed light on recruitment patterns and limitations. Rhododendron ponticum flowers are self-compatible and attract a diverse array of insects, which are responsible for a considerable number of seeds set in the populations. Nevertheless, only adults form populations, whilst seedlings are scarce and saplings virtually absent (only two juveniles out of 2489 adults sampled). Non-specialized vegetative multiplication by layering was observed. Recruitment failure seems to depend on the scarcity of safe microsites, which are free from drought, for seedling establishment. The observations contrast with R. ponticum 's reputation as an aggressive invader in temperate Atlantic areas. It is proposed that the species shows a variable balance between sexual reproduction and vegetative multiplication depending on environmental conditions. At present, only the latter seems to be prevailing in relict populations in the Iberian Peninsula. This flexible reproductive strategy is also discussed as a mechanism allowing persistence during geological climatic oscillations.  © The Linnean Society of London, Botanical Journal of the Linnean Society , 2002, 140 , 297–311.     

The Fibrin Matrix Regulates Angiogenic Responses within the Hemostatic Microenvironment through Biochemical Control

Conceptually, premature initiation of post-wound angiogenesis could interfere with hemostasis, as it relies on fibrinolysis. The mechanisms facilitating orchestration of these events remain poorly understood, however, likely due to limitations in discerning the individual contribution of cells and extracellular matrix. Here, we designed an in vitro Hemostatic-Components-Model (HCM) to investigate the role of the fibrin matrix as protein factor-carrier, independent of its cell-scaffold function. After characterizing the proteomic profile of HCM-harvested matrix releasates, we demonstrate that the key pro-/anti-angiogenic factors, VEGF and PF4, are differentially bound by the matrix. Changing matrix fibrin mass consequently alters the balance of releasate factor concentrations, with differential effects on basic endothelial cell (EC) behaviors. While increasing mass, and releasate VEGF levels, promoted EC chemotactic migration, it progressively inhibited tube formation, a response that was dependent on PF4. These results indicate that the clot’s matrix component initially serves as biochemical anti-angiogenic barrier, suggesting that post-hemostatic angiogenesis follows fibrinolysis-mediated angiogenic disinhibition. Beyond their significance towards understanding the spatiotemporal regulation of wound healing, our findings could inform the study of other pathophysiological processes in which coagulation and angiogenesis are prominent features, such as cardiovascular and malignant disease.     

The immunoglobulin heavy chain switch: structural features of gamma 1 recombinant switch regions

The immunoglobulin heavy chain isotype switch is mediated by a DNA rearrangement involving specific genomic segments referred to as switch regions. Switch regions are composed of tandemly repeated simple sequences. The role of the tandemly repeated structure of switch regions in the switch recombination process is not understood. We mapped eight recombination sites--six in the gamma 1 and two in the gamma 3 tandem arrays. In addition, we obtained molecular clones representing three of the six gamma 1 rearrangements, and determined the nucleotide sequences of the recombination sites in each. In general, the rearrangements are confined to the tandem repeat units, and are not clustered in a particular portion of either the gamma 3 or gamma 1 switch region. Nucleotide sequence analysis of one of the recombinant clones, gamma M35, reveals evidence for a successive switch event wherein a recombination between S mu and S gamma 3 was followed by recombination 57 bp downstream with S gamma 1. gamma 1 sequence data from the molecular clones we obtained, together with similar data from other investigators regarding the gamma 1, gamma 2b, and gamma 2a switch regions, reveals that recombinations tend to occur at homologous positions of the respective gamma-unit repeats, adjacent to the elements AGCT and GGGG found in each. This finding suggests that the cutting and religation step of the recombination process is mediated by a recombinase common to the four gamma-isotypes.     

Transfer of maternal plasma free fatty acids into the rat fetus.

The amount of maternal plasma free fatty acids passing to the fetus has been determined to be 0.09 mumoles fatty acids per min per each litter. Taking account of the increase of the total fetal fatty acid pool due to the fetal growth (0.2 mumoles fatty acids per min for each litter) we conclude that the maternal circulation is the source of about half of fetal fatty acids on day 21 of pregnancy.     

Ruminal ochratoxin A degradation—Contribution of the different microbial populations and influence of diet

The mycotoxin ochratoxin A (OTA) is degraded extensively in the rumen. In this study, the relative contribution of different rumen microbial populations (MP) and the effect of diet on degradation of OTA were evaluated in a factorial design experiment. Degradation of OTA was quantified by using the Hohenheim gas test (HGT) in vitro fermentation system. Five different HGT diets were used (concentrate:forage proportions (C:F) – 10:90, 30:70, 50:50, 70:30, 90:10), and donor animals were fed diets with the respective ratio. Diets with the highest concentrate content were supplied with and without 10 g/kg sodium bicarbonate (70:30 BC and 90:10 BC). The MP included whole rumen fluid, fungi + protozoa, bacteria + protozoa, protozoa and bacteria + fungi. Protozoa numbers were counted after 24 h and OTA and ochratoxin alpha (OTα) analysed at 0, 4, 8, 12, 24 h. Area under the curve (AUC) and half-life were calculated for the latter two. The short average OTA half-life for whole rumen fluid of 2.6 h (1.3–4.5 h) demonstrates the high OTA degradation capacity of the rumen MP (i.e., standard HGT inoculum) and corresponds well with published in vivo results. Both MP and diet affected OTA degradation. Interactions among factors occurred (P<0.001), which made it necessary to do further comparisons within factor levels. Among MP, those with bacteria (bacteria + fungi and bacteria + protozoa) had lower AUC values (P<0.001) for OTA (196–673 ng/ml h, meaning higher degradation capacity, than those without bacteria (fungi + protozoa and protozoa; 701–1206 ng/ml h). Whole rumen fluid had the lowest AUC values (146–249 ng/ml h; P<0.05). Diet had a quadratic effect (P=0.001) on protozoal numbers with minimum values for the lowest and highest C:F ratios, for bacteria + protozoa, fungi + protozoa and protozoa, but no corresponding effect was found for OTA degradation parameters. While the generally high capacity to degrade OTA was confirmed, results for the contribution of different microbial groups shed new light on ruminal OTA degradation.     

Enzyme-catalyzed synthesis of optically pure R(+)-phenylethanol

Summary A dehydrogenase catalyzing the NADPH-dependent reduction of acetophenone to R(+)-phenylethanol was found inLactobacillus kefir. A continuous conversion of 10 mM acetophenone with a yield of up to 90% was achieved in an enzyme-membrane-reactor with simultaneous NADPH-regeneration using glucose-6-phosphate and glucose-6-phosphate dehydrogenase. Enzyme-catalyzed oxidation of phenylethanol occurred with the R(+)-enantiomer only, whereas S(–) was not converted by the enzyme. The formation of R(+)-phenylethanol with an enantiomeric excess of 100% was confirmed by chiral HPLC.