36 research outputs found

    A Somatically Diversified Defense Factor, FREP3, Is a Determinant of Snail Resistance to Schistosome Infection

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    Schistosomiasis, a neglected tropical disease, owes its continued success to freshwater snails that support production of prolific numbers of human-infective cercariae. Encounters between schistosomes and snails do not always result in the snail becoming infected, in part because snails can mount immune responses that prevent schistosome development. Fibrinogen-related protein 3 (FREP3) has been previously associated with snail defense against digenetic trematode infection. It is a member of a large family of immune molecules with a unique structure consisting of one or two immunoglobulin superfamily domains connected to a fibrinogen domain; to date fibrinogen containing proteins with this arrangement are found only in gastropod molluscs. Furthermore, specific gastropod FREPs have been shown to undergo somatic diversification. Here we demonstrate that siRNA mediated knockdown of FREP3 results in a phenotypic loss of resistance to Schistosoma mansoni infection in 15 of 70 (21.4%) snails of the resistant BS-90 strain of Biomphalaria glabrata. In contrast, none of the 64 control BS-90 snails receiving a GFP siRNA construct and then exposed to S. mansoni became infected. Furthermore, resistance to S. mansoni was overcome in 22 of 48 snails (46%) by pre-exposure to another digenetic trematode, Echinostoma paraensei. Loss of resistance in this case was shown by microarray analysis to be associated with strong down-regulation of FREP3, and other candidate immune molecules. Although many factors are certainly involved in snail defense from trematode infection, this study identifies for the first time the involvement of a specific snail gene, FREP3, in the phenotype of resistance to the medically important parasite, S. mansoni. The results have implications for revealing the underlying mechanisms involved in dictating the range of snail strains used by S. mansoni, and, more generally, for better understanding the phenomena of host specificity and host switching. It also highlights the role of a diversified invertebrate immune molecule in defense against a human pathogen. It suggests new lines of investigation for understanding how susceptibility of snails in areas endemic for S. mansoni could be manipulated and diminished

    Effects of Cu/Zn Superoxide Dismutase (sod1) Genotype and Genetic Background on Growth, Reproduction and Defense in Biomphalaria glabrata

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    Resistance of the snail Biomphalaria glabrata to the trematode Schistosoma mansoni is correlated with allelic variation at copper-zinc superoxide dismutase (sod1). We tested whether there is a fitness cost associated with carrying the most resistant allele in three outbred laboratory populations of snails. These three populations were derived from the same base population, but differed in average resistance. Under controlled laboratory conditions we found no cost of carrying the most resistant allele in terms of fecundity, and a possible advantage in terms of growth and mortality. These results suggest that it might be possible to drive resistant alleles of sod1 into natural populations of the snail vector for the purpose of controlling transmission of S. mansoni. However, we did observe a strong effect of genetic background on the association between sod1 genotype and resistance. sod1 genotype explained substantial variance in resistance among individuals in the most resistant genetic background, but had little effect in the least resistant genetic background. Thus, epistatic interactions with other loci may be as important a consideration as costs of resistance in the use of sod1 for vector manipulation

    Specific versus Non-Specific Immune Responses in an Invertebrate Species Evidenced by a Comparative de novo Sequencing Study

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    Our present understanding of the functioning and evolutionary history of invertebrate innate immunity derives mostly from studies on a few model species belonging to ecdysozoa. In particular, the characterization of signaling pathways dedicated to specific responses towards fungi and Gram-positive or Gram-negative bacteria in Drosophila melanogaster challenged our original view of a non-specific immunity in invertebrates. However, much remains to be elucidated from lophotrochozoan species. To investigate the global specificity of the immune response in the fresh-water snail Biomphalaria glabrata, we used massive Illumina sequencing of 5′-end cDNAs to compare expression profiles after challenge by Gram-positive or Gram-negative bacteria or after a yeast challenge. 5′-end cDNA sequencing of the libraries yielded over 12 millions high quality reads. To link these short reads to expressed genes, we prepared a reference transcriptomic database through automatic assembly and annotation of the 758,510 redundant sequences (ESTs, mRNAs) of B. glabrata available in public databases. Computational analysis of Illumina reads followed by multivariate analyses allowed identification of 1685 candidate transcripts differentially expressed after an immune challenge, with a two fold ratio between transcripts showing a challenge-specific expression versus a lower or non-specific differential expression. Differential expression has been validated using quantitative PCR for a subset of randomly selected candidates. Predicted functions of annotated candidates (approx. 700 unisequences) belonged to a large extend to similar functional categories or protein types. This work significantly expands upon previous gene discovery and expression studies on B. glabrata and suggests that responses to various pathogens may involve similar immune processes or signaling pathways but different genes belonging to multigenic families. These results raise the question of the importance of gene duplication and acquisition of paralog functional diversity in the evolution of specific invertebrate immune responses

    Effect of exploitation and exploration on the innovative as outcomes in entrepreneurial firms

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    [EN] The main aim of this study is to establish the effect of the Exploitation and Exploration; and the influence of these learning flows on the Innovative Outcome (IO). The Innovative Outcome refers to new products, services, processes (or improvements) that the organization has obtained as a result of an innovative process. For this purpose, a relationship model is defined, which is empirically contrasted, and can explains and predicts the cyclical dynamization of learning flows on innovative outcome in knowledge intensive firms. The quantitative test for this model use the data from entrepreneurial firms biotechnology sector. The statistical analysis applies a method based on variance using Partial Least Squares (PLS). Research results confirm the hypotheses, that is, they show a positive dynamic effect between the Exploration and the Innovative as outcomes. 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    Occurrence of thyroid autoimmunity and dysfunction throughout a nine-month follow-up in patients undergoing interferon-beta therapy for multiple sclerosis.

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    Thyroid autoimmunity and dysfunction are a well known side effect of IFN alpha therapy for viral hepatitis and tumors, while the IFN beta effects on the thyroid gland in neurological patients have not been studied. The aim of this longitudinal study was to look for the appearance of thyroid autoimmunity as well as for the occurrence of overt thyroid disease in the patients affected by multiple sclerosis (MS) treated with IFN beta 1b. Eight patients (4 males, 4 females) undergoing r-IFN beta 1b treatment (8 M.U. every other day for 9 months) for relapsing remitting multiple sclerosis entered the study. We have analyzed thyroid function parameters and auto antibody levers before and after 1, 2, 3, 6 and 9 months of therapy. None of them referred to familiar thyroid pathology or presented clinically overt thyroid disease except for one patient (case 4) who showed TPO-Ab pretreatment positivity and another (case 8) who was in therapy with Levothyroxine 100 mu g/die for multinodular goiter. The number of patients with appearance of thyroid antibodies has slowly increased, until the third month of therapy with 3 patients out of 7 positive for TPO-Ab. The only case of overt thyroid dysfunction reported by us appeared after nine months of therapy and consisted of a hypothyroidism. Our data suggest that short-term interferon beta treatment is able to induce thyroid autoimmunity (42.8%) and dysfunction (12.5%)

    Diabetes insipidus and increased serum levels of leptin and lactate-dehydrogenase (LDH) in an adolescent boy with a primary intracranial germinoma. Case report and an endocrinological revaluation of literature.

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    A 16-year-old boy presented with a four-month history of polyuria-polydipsia and a diplopia which had reverted after treatment. The neuroimaging studies performed had been strongly suggestive of an optic nerve glioma, while endocrinological investigation (beta-hCG 420 IU/L) has lead to the correct diagnosis later confirmed at the immunohystochemical analysis performed at biopsy. The high serum level of hCG was unaffected by bromocriptine nor octreotide, while the PRL level (80.0 microg/L) was reduced only by bromocriptine. Among the several tumor markers which may be secreted by such lesions, ours is the first reported case of an elevation of serum LDH for a primary intracranial germinoma. Moreover, the elevated value of serum leptin reported by us might be due to the insensitivity of the hypothalamic structures to endogenous leptin

    Occurrence of thyroid autoimmunity and dysfunction throughout a nine-month follow-up in patients undergoing interferon-beta therapy for multiple sclerosis.

    No full text
    Thyroid autoimmunity and dysfunction are a well known side effect of IFN alpha therapy for viral hepatitis and tumors, while the IFN beta effects on the thyroid gland in neurological patients have not been studied. The aim of this longitudinal study was to look for the appearance of thyroid autoimmunity as well as for the occurrence of overt thyroid disease in the patients affected by multiple sclerosis (MS) treated with IFN beta 1b. Eight patients (4 males, 4 females) undergoing r-IFN beta 1b treatment (8 M.U. every other day for 9 months) for relapsing remitting multiple sclerosis entered the study. We have analyzed thyroid function parameters and auto antibody levels before and after 1, 2, 3, 6 and 9 months of therapy. None of them referred to familiar thyroid pathology or presented clinically overt thyroid disease except for one patient (case 4) who showed TPO-Ab pretreatment positivity and another (case 8) who was in therapy with Levothyroxine 100 microg/die for multinodular goiter. The number of patients with appearance of thyroid antibodies has slowly increased, until the third month of therapy with 3 patients out of 7 positive for TPO-Ab. The only case of overt thyroid dysfunction reported by us appeared after nine months of therapy and consisted of a hypothyroidism. Our data suggest that short-term interferon beta treatment is able to induce thyroid autoimmunity (42.8%) and dysfunction (12.5%)
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