Salmonella enterica strains belonging to O serogroup 1,3,19 induce chlorosis and wilting of Arabidopsis thaliana leaves

The number of outbreaks and illness linked to the consumption of contaminated salad leaves have increased dramatically in the last decade. Escherichia coli and Salmonella enterica are the most common food-borne pathogens linked to consumption of fresh produce. Different serovars of S. enterica subspecies enterica have been shown to bind the surface of salad leaves, to exhibit tropism towards the stomata and to invade leaves and reach the underlying mesophyll. However the consequences of leaf invasion are not known. Here we show that following infiltration, serovars Typhimurium, Enteritidis, Heidelberg and Agona, as well as strains of S. enterica subspecies arizonae and diarizonae, survive in the mesophyll of Arabidopsis thaliana leaves but induce neither leaf chlorosis nor wilting. In contrast, S. Senftenberg induced strong leaf wilting 4 days post infiltration in A. thaliana accession Col-0 but not in accession Ws-0. Dead S. Senftenberg and bacterial lysates also induced leaf wilting. We found that mutations in the Arabidopsis pathogen associated molecular pattern (PAMP) recognition receptors (PRRs) FLS2, which recognizes flagellin, and EFR, which recognizes the bacterial elongation factor EF-Tu, had no effect on the wilting response of A. thaliana to S. Senftenberg. Infiltration of A. thaliana leaves with serovars Cannstatt, Krefeld and Liverpool, which like Senftenberg belong to Salmonella serogroup E(4) (O:1,3,19), also resulted in rapid leaf wilting, while all tested rough S. Senftenberg strains (lacking the O antigen) failed to elicit leaf wilting. These results suggest that the Salmonella O antigen 1,3,19 specifically triggers leaf chlorosis and wilting in A. thaliana.     

Formulation and drying of alginate beads for controlled release and stabilization of invertase

Several alternatives to the conventional alginate beads formulation were studied for encapsulation of invertase. Pectin was added to the alginate/enzyme solution while trehalose and β-cyclodextrin were added to the calcium gelation media. The effect of composition changes, freezing, drying methods (freeze, vacuum, or air drying), and thermal treatment were evaluated on invertase stability and its release kinetics from beads. The enzyme release mechanism from wet beads depended on pH. The addition of trehalose, pectin, and β-cyclodextrin modified the bead structure, leading in some cases to a release mechanism that included the relaxation of the polymer chains, besides Fickian diffusion. Enzyme release from vacuum-dried beads was much faster than from freeze-dried beads, probably due to their higher pore size. The inclusion of β-cyclodextrin and especially of pectin prevented enzyme activity losses during bead generation, and trehalose addition was fundamental for achieving adequate invertase protection during freezing, drying, and thermal treatment. Present results showed that several alternatives such as drying method, composition, as well as pH of the relese medium can be managed to control enzyme release.     

Lizards from the end of the world: phylogenetic relationships of the Liolaemus lineomaculatus section (Squamata: Iguania: Liolaemini)

The Liolaemus lineomaculatus section is a geographically widely distributed group of lizards from the Patagonian region of southern South America, and includes 18 described species representing the most southerly distributed Liolaemus taxa (the genus includes 228 species and extends from Tierra del Fuego north to south-central Peru). Despite high species diversity, the phylogenetic relationships of this section are unknown. In the present work we sampled all described species in the L. lineomaculatus section as well as currently undescribed candidate species to reconstruct the first complete phylogenetic hypothesis for the clade. Our data set included four anonymous nuclear loci, three nuclear protein-coding loci, and two mitochondrial genes. We compared results obtained with three different phylogenetic methods for the concatenated data set (Maximum Parsimony, Maximum Likelihood and Bayesian Inference) with a coalescent-based species tree approach (BEST), and recovered congruent, strongly-supported topological arrangements across all methods. We identified four main clades within the L. lineomaculatus section: the lineomaculatus, magellanicus, somuncurae, and kingii+archeforus groups, for which we estimated divergence times. We discuss the taxonomic implications of these results and how the future integration of phylogeographic, niche modeling and morphological approaches will allow testing biogeographical hypotheses in this clade.     

Occurrence of Perkinsus olseni (Protozoa: Apicomplexa) and other parasites in the venerid commercial clam Pitar rostrata from Uruguay, southwestern Atlantic coast

A study was conducted into the health status of natural populations of the venerid clam Pitar rostrata from Uruguay. Perkinsus sp. was detected in 22% of the clams. Severe hemocytic infiltration was detected in the tissues parasitized by this protozoan parasite. The sequencing of the ITS-5.8S gene cluster of the parasite confirmed that it belonged to the Perkinsus olseni species. Rickettsia or Chlamidia-like organisms were also found, with a prevalence of 11%, although without apparent host reaction; an unidentified species of Coccidia was found in the nephridia of 78% of the clams, with the intensity of infection ranging from moderate to high. A gregarine, Nematopsis-like organism was observed mainly in the epithelial cells of the intestine, without host response and with a prevalence of 56%. Of the metazoan parasites, trematodes were found in 11% of the individuals analyzed.     

A new species of Gnathostoma (Nematoda: Gnathostomatidae) in Procyon lotor hernandezii from Mexico

Gnathostoma lamothei n. sp., inhabiting the stomach of Procyon lotor hernandezii Wagler, 1831, in Tlacotalpan, Veracruz State, and Rio Sapo, Oaxaca, Mexico, is described. This new species differs from all other congeners by having the posterior half of the body surface covered by rows of tiny round bosses instead of spines, or lacking ornamentations. Sequences of the ITS2 of the ribosomal DNA of G. lamothei n. sp. are compared with sequences of other species of the genus recorded in Mexico; they show a wide divergence (<50%) with Gnathostoma binucleatum Almeyda-Artigas, 1991, and Gnathostoma turgidum Stossich, 1902, and high similarity with Gnathostoma sp. I sequence (99.2%). On the basis of morphometric traits and sequences, previous records of Gnathostoma sp. I (=Gnathostoma procyonis of Almeyda-Artigas et al., 1994, not Chandler, 1942, and Gnathostoma neoprocyonis nomen nudem) in Mexico are referred to as the new species.     

Progesterone neuroprotection in spinal cord trauma involves up-regulation of brain-derived neurotrophic factor in motoneurons

Progesterone (PROG) provides neuroprotection to the injured central and peripheral nervous system. These effects may be due to regulation of myelin synthesis in glial cells and also to direct actions on neuronal function. Both types of cells express classical intracellular PROG receptors (PR), while neurons additionally express the PROG membrane-binding site called 25-Dx. In motoneurons from rats with spinal cord injury (SCI), PROG restores to normal the deficient levels of choline acetyl-transferase and of alpha3 subunit Na,K-ATPase mRNA, while levels of the growth associated protein GAP-43 mRNA are further stimulated. Recent studies suggest that neurotrophins are possible mediators of hormone action, and in agreement with this assumption, PROG treatment of rats with SCI increases the expression of brain-derived neurotrophic factor (BDNF) at both the mRNA and protein levels in ventral horn motoneurons. In situ hybridization (ISH) has shown that SCI reduces BDNF mRNA levels by 50% in spinal motoneurons, while PROG administration to injured rats (4mg/kg/day during 3 days, s.c.) elicits a three-fold increase in grain density. In addition to enhancement of mRNA levels, PROG increases BDNF immunoreactivity in perikaryon and cell processes of motoneurons of the lesioned spinal cord, and also prevents the lesion-induced chromatolytic degeneration of spinal cord motoneurons as determined by Nissl staining. Our findings strongly indicate that motoneurons of the spinal cord are targets of PROG, as confirmed by the expression of PR and the regulation of molecular parameters. PROG enhancement of endogenous neuronal BDNF could provide a trophic environment within the lesioned spinal cord and might be part of the PROG activated-pathways to provide neuroprotection. Thus, PROG treatment constitutes a new approach to sustain neuronal function after injury.     

Physiological routes from intra-uterine seminal contents to advancement of ovulation

Whole boar semen or seminal plasma has been demonstrated to advance the time of ovulation in gilts. As a means of clarifying this influence, the contribution of uterine lymphatics and their white cell populations has been examined. After duct visualisation with Evan's blue, lymph was sampled from a mesometrial vessel in eight pre-ovulatory gilts whose uterine lumen was infused simultaneously with whole semen in one ligated horn and saline in the contralateral ligated horn. Lymph was collected from cannulated vessels for periods of up to four hours under general anaesthesia. Thereafter, mesometrial lymph nodes, utero-tubal junction and uterine wall tissues were sampled. The proportion of nucleated cells in the sampled lymph increased towards the end of the collection period, but erythrocytes were found in all instances preventing a meaningful differentiation and identification of leukocytes. Prominent uterine lymph nodes were present in the mesometrium on both sides of the reproductive tract in 7 of 10 gilts. Differences in cellular contents were demonstrated between the side of the tract infused with semen and that infused with saline control. Two of 4 gilts had lower values for CD4 (Cluster Differentiation) and 3 of 6 gilts higher values for MHC II (Major Histocompatibility Complex) markers on the side challenged with semen. In contrast, values remained constant for CD8 but ranged widely for CD18. Immunohistochemical analysis of uterine tissue samples for MHC II+ cells revealed significant differences (P < 0.05) between the control and semen-treated ligated portions of the horns, as well as between the tissue sample of uterine wall and that from the utero-tubal junction, but there were no significant differences for CD4+ cells. It therefore remains plausible that semen-induced cytokines in the uterine lymph undergo counter-current transfer to the ipsilateral ovary and accelerate the final maturation of pre-ovulatory Graafian follicles.