Cell membrane damage induced by phenolic acids on wine lactic acid bacteria

The aim of this work was to investigate the effect of phenolic acids on cell membrane permeability of lactic acid bacteria from wine. Several phenolic acids were tested for their effects on the cell membrane of Oenococcus oeni and Lactobacillus hilgardii by measuring potassium and phosphate efflux, proton influx and by assessing culture viability employing a fluorescence technique based on membrane integrity. The experimental results indicate that hydroxycinnamic acids (p-coumaric, caffeic and ferulic acids) induce greater ion leakages and higher proton influx than hydroxybenzoic acids (p-hydroxibenzoic, protocatechuic, gallic, vanillic, and syringic acids). Among the hydroxycinnamic acids, p-coumaric acid showed the strongest effect. Moreover, the exposure of cells to phenolic acids caused a significant decrease in cell culture viability, as measured by the fluorescence assay, in both tested strains. The results agree with previous results obtained in growth experiments with the same strains. Generally, phenolic acids increased the cell membrane permeability in lactic acid bacteria from wine. The different effects of phenolic acids on membrane permeability could be related to differences in their structure and lipophilic character

Females as intraguild predators of males in crosspairing experiments with phytoseiid mites

Published online: 15 May 2013Studies on intraguild interactions between phytoseiid species have shown that intraguild predation occurs and is most commonly manifested as adult females of one species feeding on juveniles of another. Whether such intraguild interactions can also occur between adult females of one species and adult males of another, is not known. Herein, we report on intraguild interactions between adults of the two sexes in cross-pairing experiments involving three related phytoseiid species (Neoseiulus paspalivorus, N. baraki and N. neobaraki) that are potential candidates for controlling the coconut mite Aceria guerreronis, a serious pest of coconut palms in tropical countries. For comparative reasons, the experiments were repeated with larvae instead of males, and with only males or only females of two different species together. In the presence of an ample supply of prey, females of N. neobaraki never fed on individuals of their own species, yet appeared to be very aggressive against males, as well as larvae of the other two phytoseiid species. They also fed on females of N. paspalivorus, but rarely on females of N. baraki. Males of N. neobaraki did not suffer mortality when together with females of either of the two other phytoseiid species. Males of N. baraki did not suffer predation from females of N. paspalivorus, but males of N. paspalivorus suffered some mortality (15 %) from N. baraki females. Larvae of each of the three species were vulnerable to intraguild predation by heterospecific adult females, except for N. neobaraki larvae when together with N. baraki females. The absence or presence of intraguild predation is largely explained by the size ratios of the individuals that were put together: large individuals feed on smaller ones, but never the reverse. For each sex, size declines in the following order: N. neobaraki > N. baraki > N. paspalivorus. Moreover, for each species, females are larger than males and males are larger than larvae. Strikingly, however, females did not kill males and larvae of their own species. We propose that niche competition between related phytoseiid species is not only determined by intraguild predation on heterospecific larvae, but also by imposing great mortality on males from the intraguild prey because phytoseiid females being pseudo-arrhenotokous require insemination to produce offspring of both sexes

Morphological, molecular and crossbreeding analysis of geographic populations of coconutmite associated predatory mites identified as Neoseiulus baraki: evidence for cryptic species?

Published online: 11 March 2012Surveys were conducted in Brazil, Benin and Tanzania to collect predatory mites as candidates for control of the coconut mite Aceria guerreronis Keifer, a serious pest of coconut fruits. At all locations surveyed, one of the most dominant predators on infested coconut fruits was identified as Neoseiulus baraki Athias-Henriot, based on morphological similarity with regard to taxonomically relevant characters. However, scrutiny of our own and published descriptions suggests that consistent morphological differences may exist between the Benin population and those from the other geographic origins. In this study, we combined three methods to assess whether these populations belong to one species or a few distinct, yet closely related species. First, multivariate analysis of 32 morphological characters showed that the Benin population differed from the other three populations. Second, DNA sequence analysis based on the mitochondrial cytochrome oxidase subunit I (COI) showed the same difference between these populations. Third, cross-breeding between populations was unsuccessful in all combinations. These data provide evidence for the existence of cryptic species. Subsequent morphological research showed that the Benin population can be distinguished from the others by a new character (not included in the multivariate analysis), viz. the number of teeth on the fixed digit of the female chelicera

Multi-dimensional computed cardiac visualization

During the past decade, coronary radiology has undergone rapid development. This second edition of the only available monograph on the subject places special emphasis on the role of non-invasive techniques, which can supply information on the condition of the coronary arteries within one simple and short examination. The modalities considered in detail include CT angiography with multidetector and dual-source tomography, 2D and 3D visualization techniques, and MR coronary angiography. Invasive procedures are not neglected, however, and a separate section includes chapters on conventional catheterization, quantitative angiography, and intravascular and quantitative ultrasound. In addition, a section devoted to coronary calcification clearly explains its development and the use of modern techniques in its visualization and quantification. The informative text is supported by a large number of high-quality color images of the coronary and cardiac anatomy