Gender dimorphism influences extracellular matrix expression and regeneration of muscular tissue in mdx dystrophic mice

Mdx mouse, the animal model of Duchenne muscular dystrophy, lacks dystrophin and develops an X-linked recessive inflammatory myopathy characterized by degeneration of skeletal muscle fibers and connective tissue replacement. The present work aimed to assess whether gender dimorphism in mdx mice would influence skeletal muscle pathology at ages corresponding to main histological changes in the microenvironment of muscular tissue: myonecrosis, regeneration, and fibrosis. At the height of myonecrosis (6 weeks postnatal), skeletal muscles of male mdx mice showed increased sarcolemmal permeability, numerous inflammatory foci, and marked deposition of the extracellular matrix components (ECM) type I collagen and laminin. In contrast, age-matched mdx females showed mild ECM deposition, discrete myonecrosis, but increased numbers of regenerating fibers expressing the satellite cell marker NCAM. In contrast ovariectomized mdx females showed decreased numbers of regenerating fibers. Older (24 and 48 weeks postnatal) mdx females showed extensive fibrosis with increased sarcolemmal permeability and marked deposition of ECM components than corresponding males. These results suggest a role for female hormones in the control of myonecrosis probably by promoting regeneration of muscular tissue and mitigating inflammation especially at ages under the critical influence of sex hormones.     

BRL1 and BRL3 are novel brassinosteroid receptors that function in vascular differentiation in Arabidopsis

Plant steroid hormones, brassinosteroids (BRs), are perceived by the plasma membrane-localized leucine-rich-repeat-receptor kinase BRI1. Based on sequence similarity, we have identified three members of the BRI1 family, named BRL1, BRL2 and BRL3. BRL1 and BRL3, but not BRL2, encode functional BR receptors that bind brassinolide, the most active BR, with high affinity. In agreement, only BRL1 and BRL3 can rescue bri1 mutants when expressed under the control of the BRI1 promoter. While BRI1 is ubiquitously expressed in growing cells, the expression of BRL1 and BRL3 is restricted to non-overlapping subsets of vascular cells. Loss-of-function of brl1 causes abnormal phloem:xylem differentiation ratios and enhances the vascular defects of a weak bri1 mutant. bri1 brl1 brl3 triple mutants enhance bri1 dwarfism and also exhibit abnormal vascular differentiation. Thus, Arabidopsis contains a small number of BR receptors that have specific functions in cell growth and vascular differentiation.     

ERK signaling is required for eye-specific retino-geniculate segregation

In the mammalian visual system, retinal ganglion cell (RGC) projections from each eye, initially intermixed within the dorsal-lateral geniculate nucleus (dLGN), become segregated during the early stages of development, occupying distinct eye-specific layers. Electrical activity has been suggested to play a role in this process; however, the cellular mechanisms underlying eye-specific segregation are not yet defined. It is known that electrical activity is among the strongest activators of the extracellular signal-regulated kinase (ERK) pathway. Moreover, the ERK pathway is involved in the plasticity of neural connections during development. We examine the role of ERK in the segregation of retinal afferents into eye-specific layers in the dLGN. The activation of this signaling cascade was selectively blocked along the retino-thalamic circuitry by specific inhibitors, and the distribution of RGC fibers in the dLGN was studied. Our results demonstrate that the blockade of ERK signaling prevents eye-specific segregation in the dLGN, providing evidence that ERK pathway is required for the proper development of retino-geniculate connections. Of particular interest is the finding that ERK mediates this process both at the retinal and geniculate level.     

Role of the GGDEF protein family in Salmonella cellulose biosynthesis and biofilm formation

Salmonella enterica serovar Typhimurium is capable of producing cellulose as the main exopolysaccharide compound of the biofilm matrix. It has been shown for Gluconacetobacter xylinum that cellulose biosynthesis is allosterically regulated by bis-(3',5') cyclic diguanylic acid, whose synthesis/degradation depends on diguanylate cyclase/phosphodiesterase enzymatic activities. A protein domain, named GGDEF, is present in all diguanylate cyclase/phosphodiesterase enzymes that have been studied to date. In this study, we analysed the molecular mechanisms responsible for the failure of Salmonella typhimurium strain SL1344 to form biofilms under different environmental conditions. Using a complementation assay, we were able to identify two genes, which can restore the biofilm defect of SL1344 when expressed from the plasmid pBR328. Based on the observation that one of the genes, STM1987, contains a GGDEF domain, and the other, mlrA, indirectly controls the expression of another GGDEF protein, AdrA, we proceeded on a mutational analysis of the additional GG[DE]EF motif containing proteins of S. typhimurium. Our results demonstrated that MlrA, and thus AdrA, is required for cellulose production and biofilm formation in LB complex medium whereas STM1987 (GGDEF domain containing protein A, gcpA) is critical for biofilm formation in the nutrient-deficient medium, ATM. Insertional inactivation of the other six members of the GGDEF family (gcpB-G) showed that only deletion of yciR (gcpE) affected cellulose production and biofilm formation. However, when provided on plasmid pBR328, most of the members of the GGDEF family showed a strong dominant phenotype able to bypass the need for AdrA and GcpA respectively. Altogether, these results indicate that most GGDEF proteins of S. typhimurium are functionally related, probably by controlling the levels of the same final product (cyclic di-GMP), which include among its regulatory targets the cellulose production and biofilm formation of S. typhimurium.     

1alpha,25(OH)2D3 and parathyroid hormone (PTH) signaling in rat intestinal cells: activation of cytosolic PLA2

In the current study, we have probed the role of cytosolic phospholipase A2 (cPLA2) activity in the cellular response to the calciotropic hormones, 1alpha,25,dihydroxy-vitamin D(3) [1alpha,25(OH)(2)D(3)] and PTH. Stimulation of rat enterocytes with either hormone, increased release of arachidonic acid (AA) 3H-AA] one-two fold in a concentration and time-dependent manner. The effect of either hormone on enterocytes was totally reduced by preincubation with the intracellular Ca(2+) chelator BAPTA-AM (5 microM), suggesting that the release of AA following cell exposure to the calciotropic hormones occurs mainly through a Ca(2+)-dependent mechanism involving activation of Ca(2+)-dependent cPLA2. Calciotropic homone stimulation of rat intestinal cells increases cPLA2 phosphorylation (three to four fold). This effect was decreased by PD 98059 (20 microM), a MAP kinase inhibitor, indicating that this action is, in part, mediated through activation of the MAP kinases ERK 1 and ERK2. Enterocytes exposure to 1alpha,25(OH)(2)D(3) (1nM) or PTH (10 nM) also resulted in P-cPLA2 translocation from cytosol to nuclei and membrane fractions, where phospholipase subtrates reside. Collectively, these data suggest that PTH and 1alpha,25(OH)(2)D(3) activate in duodenal cells, a Ca(2+)-dependent cytosolic PLA2 and attendant arachidonic acid release and that this activation requieres prior stimulation of intracellular ERK1/2. 1alpha,25(OH)(2)D(3) and PTH modulation of cPLA2 activity may change membrane fluidity and permeability and thereby affecting intestinal cell membrane function.     

Molecular cloning of the potato Gro1-4 gene conferring resistance to pathotype Ro1 of the root cyst nematode Globodera rostochiensis, based on a candidate gene approach

The endoparasitic root cyst nematode Globodera rostochiensis causes considerable damage in potato cultivation. In the past, major genes for nematode resistance have been introgressed from related potato species into cultivars. Elucidating the molecular basis of resistance will contribute to the understanding of nematode-plant interactions and assist in breeding nematode-resistant cultivars. The Gro1 resistance locus to G. rostochiensis on potato chromosome VII co-localized with a resistance-gene-like (RGL) DNA marker. This marker was used to isolate from genomic libraries 15 members of a closely related candidate gene family. Analysis of inheritance, linkage mapping, and sequencing reduced the number of candidate genes to three. Complementation analysis by stable potato transformation showed that the gene Gro1-4 conferred resistance to G. rostochiensis pathotype Ro1. Gro1-4 encodes a protein of 1136 amino acids that contains Toll-interleukin 1 receptor (TIR), nucleotide-binding (NB), leucine-rich repeat (LRR) homology domains and a C-terminal domain with unknown function. The deduced Gro1-4 protein differed by 29 amino acid changes from susceptible members of the Gro1 gene family. Sequence characterization of 13 members of the Gro1 gene family revealed putative regulatory elements and a variable microsatellite in the promoter region, insertion of a retrotransposon-like element in the first intron, and a stop codon in the NB coding region of some genes. Sequence analysis of RT-PCR products showed that Gro1-4 is expressed, among other members of the family including putative pseudogenes, in non-infected roots of nematode-resistant plants. RT-PCR also demonstrated that members of the Gro1 gene family are expressed in most potato tissues.     

Patterns of use and knowledge of wild edible plants in distinct ecological environments: a case study of a Mapuche community from northwestern Patagonia

The multiple use of distinct ecological environments in the search for wild resources has been practiced since ancestral times in aboriginal communities inhabiting northwestern Patagonia. This paper examines the actual use and knowledge of wild edible plants in a Mapuche community presently settled in one of the most arid areas of Patagonia, far from the temperate forests where their ancestors used to live. The difference between knowledge of and use of wild plants is analyzed emphasizing that these differences could contribute to the understanding of eroding processes believed to be occurring in the community. These objectives are studied quantitatively by utilizing ethnobotanical indices, partially derived from ecological theory. Our results indicate that the Paineo dwellers still utilize multiple ecological gathering environments and have thorough plant knowledge of both native and exotic species. The Andean forest, more than 50km away from this community, is the environment from which the Paineo dwellers know the greatest total richness and the highest diversity of wild edible plants, followed by the Monte–Steppe species and lastly, those growing around their homes. The transmission of wild edible plant knowledge in the Paineo community diminishes with age, and the forest plants are the most vulnerable to loss. Our results have shown that the knowledge and consumption of wild edible plants follows a pattern according to ecological conditions of the gathering environments, as well as the cultural heritage of the Paineo people.     

ApoE genotyping and response to galanthamine in Alzheimer's disease--a real life retrospective study

This study was undertaken to evaluate the effect of galanthamine, a new cholinesterase inhibitor on cognitive performances in 84 patients with various apoE genotype and Alzheimer's disease (AD) during the six-month treatment. The diagnosis of AD was made on the basis of NINCDS/ADRDN criteria. ApoE4 genotype was determined by PCR procedure. The cognitive performance was assessed MMSE at baseline and six months later. The difference among the groups was statistically analyzed by ANOVA model and Pearson's chi2-test. The MMSE at baseline in all completes was 18.0 +/- 3.73, whereas the mean value of MMSE after 6 months was 16.4 +/- 5.61 indicating significant deterioration (p < 0.01). Of the 84 patients, 14 (169%) were apoE4 homozygous, 41 (49%) were heterozygous, whereas 29 (35%) were apoE4 negative. The significant number of responders was observed among apoE4 homozygous patients (71%; chi2 = 6.89; p = 0.032). The subgroup of apoE4 homozygous patients with AD in its mild to moderate stage may be considered as responders to galanthamine.