Intestinal Dysbiosis and Yeast Isolation in Stool of Subjects with Autism Spectrum Disorders

High frequency of gastrointestinal yeast presence in ASD subjects was shown through a simple cultural approach (Candida spp. in 57.5 % of ASDs and no controls); the identification of aggressive form (pseudo-hyphae presenting) of Candida spp. at light microscope means that adhesion to intestinal mucosa is facilitated. Dysbiosis appears sustained by lowered Lactobacillus spp. and decreased number of Clostridium spp. Absence of C. difficilis and its toxins in both ASDs and controls is also shown. Low-mild gut inflammation and augmented intestinal permeability were demonstrated together with the presence of GI symptoms. Significant linear correlation was found between disease severity (CARs score) and calprotectin and Clostridium spp. presence. Also GI symptoms, such as constipation and alternating bowel, did correlate (multivariate analyses) with the increased permeability to lactulose. The present data provide rationale basis to a possible specific therapeutic intervention in restoring gut homeostasis in ASDs.     

Indirect facilitation by a liana might explain the dominance of a small tree in a temperate forest

Aims Lianas are expected to influence composition, structure and functioning of forest systems due to unequal distribution across the potential set of host plants. However, our understanding of mechanisms associated with preferences for specific hosts is still limited, and so is our ability to discern between endogenous and exogenous forces driving forest dynamics in the long run. In this paper, we evaluated whether the dominant liana Hedera helix can indirectly contribute to the eventual dominance of the small multi-stemmed tree Corylus avellana in a remnant temperate forest in central Iberian Peninsula from comparatively reduced liana infestation on C. avellana relative to co-occurring woody species.Methods Through principal component analysis and co-occurrence analysis, we studied the distribution and spatial association between woody species and the liana H. helix. We analyzed the relationship between the number of species in a plot and the number of species infested by the liana to test the hypothesis that H. helix is a generalist liana. Through generalized linear mixed models, we tested the dynamic-multi-stemmed growth form of C. avellana as a plausible life strategy to withstand, in the long run, the liana infestation. In particular, we tested (i) the relationship between stem size and the probability of H. helix infestation including all the tree species within plots and (ii) the relationship between stem size and mortality as evidence of the stem turn over in the tree C. avellana .Important findings Our results indicate that H. helix and C. avellana significantly co-occur in mature stands of this remnant temperate forest where pioneer woody species are absent. Hedera helix severely infests all the woody species whenever stem size exceed ≈25 cm perimeter and there is physical contact at the base of the stem. This implies that all the trees in the community are potential hosts for H. helix. Mixed models indicate that both, infestation by H. helix and stem mortality, are positively related to C. avellana stem perimeter. Reduced long-term infestation of the liana by means of a multi-stemmed growth form with high stem turnover in C. avellana might be an advantage with respect to unipodial tree species. Thus, the liana-tree coexistence pattern may be interpreted as an indirect positive interaction that, contrary to previous findings, results here in species dominance instead of species coexistence.     

Ecophysiological basis of the Jack-and-Master strategy: Taraxacum officinale (dandelion) as an example of a successful invader

Aims Successful invasive plants are often assumed to display significant levels of phenotypic plasticity. Three possible strategies by which phenotypic plasticity may allow invasive plant species to thrive in changing environments have been suggested: (i) via plasticity in morphological or physiological traits, invasive plants are able to maintain a higher fitness than native plants in a range of environments, including stressful or low-resource habitats: a 'Jack-of-all-trades' strategy; (ii) phenotypic plasticity allows the invader to better exploit resources available in low stress or favorable habitats, showing higher fitness than native ones: a 'Master-of-some' strategy and (iii) a combination of these abilities, the 'Jack-and-Master' strategy.Methods We evaluated these strategies in the successful invader Taraxacum officinale in a controlled experiment mimicking natural environmental gradients. We set up three environmental gradients consisting of factorial arrays of two levels of temperature/light, temperature/water and light/water, respectively. We compared several ecophysiological traits, as well as the reaction norm in fitness-related traits, in both T. officinale and the closely related native Hypochaeris thrincioides subjected to these environmental scenarios.Important findings Overall, T. officinale showed significantly greater accumulation of biomass and higher survival than the native H. thrincioides, with this difference being more pronounced toward both ends of each gradient. T. officinale also showed significantly higher plasticity than its native counterpart in several ecophysiological traits. Therefore, T. officinale exhibits a Jack-and-Master strategy as it is able to maintain higher biomass and survival in unfavorable conditions, as well as to increase fitness when conditions are favorable. We suggest that this strategy is partly based on ecophysiological responses to the environment, and that it may contribute to explaining the successful invasion of T. officinale across different habitats.     

Studies on the effects of carbon:nitrogen ratio, inoculum type and yeast extract addition on jasmonic acid production by Botryodiplodia theobromae Pat. strain RC1

Jasmonic acid is a native plant growth regulator produced by algae, microorganisms and higher plants. This regulator is involved in the activation of defence mechanisms against pathogens and wounding in plants. Studies concerning the effects of carbon: nitrogen ratio (C/Nr: 17, 35 and 70), type of inoculum (spores or mycelium) and the yeast extract addition in the media on jasmonic acid production by Botryodiplodia theobromae were evaluated. Jasmonic acid production was stimulated at the carbon: nitrogen ratio of 17. Jasmonic acid productivity was higher in the media inoculated with mycelium and in the media with yeast extract 1.7 and 1.3 times, respectively.     

The novel mouse mutation Oblivion inactivates the PMCA2 pump and causes progressive hearing loss

Progressive hearing loss is common in the human population, but we have few clues to the molecular basis. Mouse mutants with progressive hearing loss offer valuable insights, and ENU (N-ethyl-N-nitrosourea) mutagenesis is a useful way of generating models. We have characterised a new ENU-induced mouse mutant, Oblivion (allele symbol Obl), showing semi-dominant inheritance of hearing impairment. Obl/+ mutants showed increasing hearing impairment from post-natal day (P)20 to P90, and loss of auditory function was followed by a corresponding base to apex progression of hair cell degeneration. Obl/Obl mutants were small, showed severe vestibular dysfunction by 2 weeks of age, and were completely deaf from birth; sensory hair cells were completely degenerate in the basal turn of the cochlea, although hair cells appeared normal in the apex. We mapped the mutation to Chromosome 6. Mutation analysis of Atp2b2 showed a missense mutation (2630C→T) in exon 15, causing a serine to phenylalanine substitution (S877F) in transmembrane domain 6 of the PMCA2 pump, the resident Ca²⁺ pump of hair cell stereocilia. Transmembrane domain mutations in these pumps generally are believed to be incompatible with normal targeting of the protein to the plasma membrane. However, analyses of hair cells in cultured utricular maculae of Obl/Obl mice and of the mutant Obl pump in model cells showed that the protein was correctly targeted to the plasma membrane. Biochemical and biophysical characterisation showed that the pump had lost a significant portion of its non-stimulated Ca²⁺ exporting ability. These findings can explain the progressive loss of auditory function, and indicate the limits in our ability to predict mechanism from sequence alone.     

Raphidophyceans on the coasts of Mexico

The annual loads of C,N,P, silicate, total suspended sediment (mass) and their yields (mass area^?1) were estimated for six watersheds of the Mississippi River Basin (MRB) using water quality and water discharge records for 1973 to 1994. The highest load of suspended sediments is from the Missouri watershed (58 mt km² yr^?1), which is also the largest among the six major sub-basins. The Ohio watershed delivers the largest load of water (38%). The Upper Mississippi has the largest total nitrogen load (32%) and yield (1120 kg TN km² yr^?1). The loading of organic carbon, total phosphorus and silicate from the Upper Mississippi and Ohio watersheds are similar and relatively high (range 2.1–2.5, 0.068–0.076, and 0.8–1.1 mt km² yr^?1, respectively). The yields of suspended sediments, total phosphorus, total nitrogen, and silicate from the Lower Mississippi watershed are disproportionately the highest for its area, which is the smallest of all the watersheds and has the weakest monitoring network. The loading from the Red and Arkansas watersheds are of lesser importance than the others for most parameters investigated. The total nitrogen loading to coastal waters increased an additional 150% since the early 1900s, and is now dominated by loads from the Upper Mississippi watershed, rather than the previously dominant Ohio watershed. An analysis of trends for 1973–1994 suggests variability among years, rather than uni-directional change for most variables among 11 key stations. Explanatory relationships were established or confirmed to describe TN and TP loadings in terms of the now largely human-created landscape arising mostly over the last 150 years.     

Vesicular transport in Histoplasma capsulatum: an effective mechanism for trans-cell wall transfer of proteins and lipids in ascomycetes

Vesicular secretion of macromolecules has recently been described in the basidiomycete Cryptococcus neoformans , raising the question as to whether ascomycetes similarly utilize vesicles for transport. In the present study, we examine whether the clinically important ascomycete Histoplasma capsulatum produce vesicles and utilized these structures to secrete macromolecules. Transmission electron microscopy (TEM) shows transcellular secretion of vesicles by yeast cells. Proteomic and lipidomic analyses of vesicles isolated from culture supernatants reveal a rich collection of macromolecules involved in diverse processes, including metabolism, cell recycling, signalling and virulence. The results demonstrate that H. capsulatum can utilize a trans-cell wall vesicular transport secretory mechanism to promote virulence. Additionally, TEM of supernatants collected from Candida albicans , Candida parapsilosis , Sporothrix schenckii and Saccharomyces cerevisiae documents that vesicles are similarly produced by additional ascomycetes. The vesicles from H. capsulatum react with immune serum from patients with histoplasmosis, providing an association of the vesicular products with pathogenesis. The findings support the proposal that vesicular secretion is a general mechanism in fungi for the transport of macromolecules related to virulence and that this process could be a target for novel therapeutics.     

Generation of a reporter mouse line expressing Akt and EGFP upon Cre-mediated recombination

The serine-threonine kinase Akt regulates multiple biological processes. An important strategy to study Akt signaling in different tissues is targeted activation of this pathway in vivo. The current studies describe the generation of a mouse model that combines a double reporter system with activation of a constitutively active form of Akt1 (caAkt) in a Cre-dependent manner. Before Cre recombination, these mice express LacZ during development as well as in most adult tissues. After Cre-mediated excision of the LacZ reporter, functionality of the transgene was demonstrated by expression of the caAkt mutant along with the second reporter, EGFP in different pancreatic compartments and in the nervous system. This animal model provides a critical reagent for assessing the effects of Akt activation in specific tissues. The lineage-tracing properties provide a useful tool to study the role of Akt signaling in regulation of differentiation programs during development and plasticity of mature tissues.     

Morphological plasticity in response to shading in three Convolvulus species of different ecological breadth

We evaluated in common-garden experiments the morphological plasticity to shading of three Convolvulus species that occur in Chile and differ in ecological breadth. Convolvulus arvensis L. is a world weed distributed along the country, and is found in open as well as in shaded habitats. Convolvulus chilensis Pers. is a Chilean endemic species typical of coastal habitats, and is found in open to partially open sites. C. demissus choisy occurs only on slopes of the Andes of Chile and Argentina, habitats with high incidence of solar radiation. We hypothesized that the magnitude of phenotypic plasticity to shading of these species would correlate with their ecological breadth. Shading had a significant effect on internode length, petiole length, stem diameter, stem length, number of branches, leaf area, leaf shape, leaf biomass, and specific leaf area. Species differed in all the morphological traits except leaf biomass. A significant Shading × Species interaction in the two-way ANOVA, i.e. differential plasticity to shading of Convolvulus species, was found for petiole length, stem length, number of branches, leaf shape, and specific leaf area. Contrary to our hypothesis, tests of parallelism showed that, in general, the plasticity to shading of C. chilensis (the species of intermediate ecological breadth) was the greatest, and that of C. arvensis (the weed) and C. demissus (the species of narrow distribution) was similar. Issues of ecotype differentiation, in the case of C. arvensis, and the role of life history traits are raised to explain the observed lack of association between ecological breadth and magnitude of phenotypic plasticity.