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PubMed1992

Early and multifocal tumors in breast, salivary, harderian and epididymal tissues developed in MMTY-Neu transgenic mice.

Transgenic mice carrying various oncogenes driven by mammary gland specific enhancers develop mammary tumors usually arising in a stochastic way. The only exception is a mouse lineage (TG.NF) carrying an activated rat Neu oncogene driven by the murine mammary tumor virus long terminal repeat (MMTV-LTR) that gave rise to rapid and multifocal mammary tumors interpreted as a result of a single-step neoplastic transformation. The effect of the oncogene appeared to be specific for breast tissue, since salivary and Harderian glands as well as epididymis expressed high levels of Neu but only developed hyperplasia (Muller et al., Cell, (1988) 54, p. 105). Here we describe a transgenic mouse lineage for the MMTV-Neu, analysed up to third generation. Multifocal tumors involving mammary glands arose very rapidly in all females independently from pregnancy and in some males. Moreover, multifocal neoplasias occurred also in salivary and Harderian glands and in the epididymis at a very high rate. These data demonstrate that the Neu oncogene can induce tumors in all the tissues where it is expressed at high levels.

Animals↗
PubMed1998

Cloning of murine low molecular weight phosphotyrosine protein phosphatase cDNA: identification of a new isoform.

The low molecular weight phosphotyrosine protein phosphatase (LMW-PTP) is a 18 kDa cytosolic enzyme, involved in the negative regulation of cell proliferation. In different mammalian species LMW-PTPs are expressed in two molecular forms produced from a single primary transcript through an alternative splicing mechanism. In this paper we report the cloning, expression and characterization of mouse isoforms of LMW-PTPs (called m-IF1 and m-IF2), very similar to the corresponding rat and human isoenzymes. Moreover we have identified a third cDNA encoding a protein (m-IF2P) that presents three substitutions compared to m-IF2. This new isoform is still active on pNPP, although to a lower extent: this reduction is mainly due to the leucine to proline substitution in position 13, within the catalytic loop. The mRNA expression level of this isoform is comparable to those of m-IF1 and m-IF2. It is likely that a gene duplication process followed by mutations has generated this new gene.

3T3 Cells↗
PubMed2000

Proteasome inhibitor induced gene expression profiles reveal overexpression of transcriptional regulators ATF3, GADD153 and MAD1.

The ubiquitin/proteasome pathway has been implicated in a wide variety of cellular processes and the number of substrates degraded by the proteasome is impressive. Most prominently, the stability of a large number of transcription factors is regulated by ubiquitination. To elucidate pathways regulated by the proteasome, gene expression profiles were generated, comparing changes of mRNA expression of 7900 genes from the UniGene collection upon exposure of cells to the proteasome inhibitors Lactacystin, Lactacystin-beta-lactone or MG132 by means of microarray based cDNA hybridization. The three profiles were very similar, but differed significantly from a gene expression profile generated with the histone deacetylase inhibitor Trapoxin A, indicating that the observed alterations were indeed due to proteasome inhibition. Two of the most prominently induced genes encoded the growth arrest and DNA damage inducible protein Gadd153 and the activating transcription factor ATF3, both transcription factors of the CCAAT/enhancer binding protein (C/EBP) family. A third gene encoded for the transcriptional repressor and c-Myc antagonist Mad1. Our results suggest that proteasome inhibition leads to upregulation of specific members of transcription factor families controlling cellular stress response and proliferation. Oncogene (2000).

Base Sequence↗
PubMed1991

Molecular genetic basis for complex flagellar antigen expression in a triphasic serovar of Salmonella.

Strains of most Salmonella serovars produce either one (monophasic) or two (diphasic) antigenic forms of flagellin protein, but strains capable of expressing three or more serologically distinct flagellins ("complex" serovars) have occasionally been reported. A molecular genetic analysis of a triphasic strain of the normally diphasic serovar Salmonella rubislaw revealed that it has three flagellin genes, including the normal fliC (phase 1) and fljB (phase 2) chromosomal genes encoding type r and type e,n,x flagellins, respectively, and a third locus (herein designated as flpA) that is located on a large plasmid (pRKS01) and codes for a type d flagellin. The coding sequence of the plasmid-borne gene is similar to that of a phase 1 chromosomal gene, but the sequence of its promoter region is homologous to that of a phase 2 chromosomal gene. The irreversible loss of the ability to express a type d flagellin that occurs when the triphasic strain is grown in the presence of d antiserum is caused by deletion of part or all of the flpA gene. Thus, the molecular basis for the unusual serological reactions of the triphasic strain of S. rubislaw and, by inference, other complex serovars of Salmonella is explained. Plasmids of the type carried by the triphasic strain of S. rubislaw provide a mechanism for the generation of new serovars through the lateral transfer and recombination of flagellin genes.

Base Sequence↗
PubMed1995

Frequency and fidelity of translesion synthesis of site-specific N-2-acetylaminofluorene adducts during DNA replication in a human cell extract.

We have previously analyzed the effects of site-specific N-2-acetylaminofluorene (AAF) adducts on the efficiency and frameshift fidelity of SV40-based DNA replication in a human cell extract (Thomas, D. C., Veaute, X., Kunkel, T. A., and Fuchs, R. P. P. (1994) Proc. Natl. Acad. Sci. U.S.A. 91, 7752-7756). Here we use two sets of substrates to examine the probability of replication termination and error-free and error-prone bypass of AAF adducts. The substrates contained site-specific adducts at one of three guanines in a NarI sequence (5'-GGCGCC-3') placed within the lacZ alpha reporter gene and located on the template for either leading or lagging strand replication. The presence of the adduct at any position strongly reduces the efficiency of a single round of replication in a HeLa cell extract. Product analysis reveals preferential replication of the undamaged strand and termination of replication of the damaged strand occurring one nucleotide before incorporation opposite either a leading or lagging strand adduct. Products resistant to restriction endonuclease cleavage at the adducted site were generated in amounts consistent with 16-48% lesion bypass during replication. Most of this bypass was error-free. However, two-nucleotide deletion errors were detected in the replication products of DNA containing an AAF adduct in either the leading or lagging strand, but only when present at the third guanine position. Collectively, the data suggest that the replication apparatus in a HeLa cell extract generates a template-primer slippage error at an AAF adduct once for every 30-100 bypass events.

2-Acetylaminofluorene↗
PubMed2002

Downstream codons in the retinoic acid receptor beta -2 and beta -4 mRNAs initiate translation of a protein isoform that disrupts retinoid-activated transcription.

Retinoic acid receptors (RARs) are essential for the differentiation and maintenance of normal epithelium. In studies of RARs in breast cancer, there are striking differences in the expression of certain protein isoforms of the RARbeta gene between cells derived from normal human mammary glands and those derived from breast tumors. While the protein isoforms RARbeta2 and RARbeta4 consist of the longest open reading frames of the RARbeta2 and RARbeta4 mRNAs, respectively, we find that a fraction of scanning ribosomes bypass these upstream RARbeta2 and RARbeta4 protein start codons and initiate translation downstream. This downstream translation initiation site is identical in the RARbeta2 and RARbeta4 transcripts and generates a third RARbeta protein isoform, here termed RARbeta' (formerly human RARbeta4). RARbeta' lacks protein domains found in the N terminus of RARbeta2 and RARbeta4, including one of two zinc fingers required for DNA binding. However, RARbeta' retains the ability to heterodimerize with RXRalpha and interact with transcription cofactors. In reporter gene assays, RARbeta' repressed retinoic acid-activated transcription of co-transfected RARbeta2, RARbeta4, and RARalpha. This repression required the presence of acidic amino acids within the AF2 domain. These findings demonstrate an antagonistic role for RARbeta' in signaling by retinoic acid.

Base Sequence↗
PubMed2005

The chloroplast genome of Phalaenopsis aphrodite (Orchidaceae): comparative analysis of evolutionary rate with that of grasses and its phylogenetic implications.

Whether the Amborella/Amborella-Nymphaeales or the grass lineage diverged first within the angiosperms has recently been debated. Central to this issue has been focused on the artifacts that might result from sampling only grasses within the monocots. We therefore sequenced the entire chloroplast genome (cpDNA) of Phalaenopsis aphrodite, Taiwan moth orchid. The cpDNA is a circular molecule of 148,964 bp with a comparatively short single-copy region (11,543 bp) due to the unusual loss and truncation/scattered deletion of certain ndh subunits. An open reading frame, orf91, located in the complementary strand of the rrn23 was reported for the first time. A comparison of nucleotide substitutions between P. aphrodite and the grasses indicates that only the plastid expression genes have a strong positive correlation between nonsynonymous (Ka) and synonymous (Ks) substitutions per site, providing evidence for a generation time effect, mainly across these genes. Among the intron-containing protein-coding genes of the sampled monocots, the Ks of the genes are significantly correlated to transitional substitutions of their introns. We compiled a concatenated 61 protein-coding gene alignment for the available 20 cpDNAs of vascular plants and analyzed the data set using Bayesian inference, maximum parsimony, and neighbor-joining (NJ) methods. The analyses yielded robust support for the Amborella/Amborella-Nymphaeales-basal hypothesis and for the orchid and grasses together being a monophyletic group nested within the remaining angiosperms. However, the NJ analysis using Ka, the first two codon positions, or amino acid sequences, respectively, supports the monocots-basal hypothesis. We demonstrated that these conflicting angiosperm phylogenies are most probably linked to the transitional sites at all codon positions, especially at the third one where the strong base-composition bias and saturation effect take place.

DNA, Chloroplast↗
PubMed2006

High-resolution structure of recombinant Trichomonas vaginalis thioredoxin.

The structure of thioredoxin from the anaerobic organism Trichomonas vaginalis (TvTrx) has been determined at 1.9 angstroms resolution. The structure is that of a typical thioredoxin: a five-stranded beta-sheet structure with two alpha-helices on either side. The active site of the protein carries a Trp-Cys-Gly-Pro-Cys motif, residues 34-38, at the N-terminus of an alpha-helix (alpha2). The cysteine residues in this motif form a redox-active disulfide necessary for thioredoxin activity. With high-resolution data available, it was possible to model numerous amino-acid side chains in alternate conformations and this includes the redox-active disulfide cysteine residues. The sample was initially in the oxidized state and the use of X-rays from an intense third-generation synchrotron source resulted in partial photoreduction of this labile redox centre. Comparisons with previously determined thioredoxin structures indicate that TvTrx is most similar to the human homologue, although the insertion of three residues between strands beta4 and beta5 makes the corresponding turn longer and more flexible in TvTrx. In addition, three significant amino-acid differences are identified on the protein surfaces near to the active-site Cys35. These residues may contribute to the interactions that specific thioredoxins form with their cognate physiological partners.

Amino Acid Sequence↗
PubMed2004

Two genes encoding Arabidopsis halleri MTP1 metal transport proteins co-segregate with zinc tolerance and account for high MTP1 transcript levels.

The zinc hyperaccumulator plant Arabidopsis halleri is able to naturally accumulate 100-fold higher leaf zinc concentrations when compared with non-accumulator species such as the closely related A. lyrata and A. thaliana, without showing toxicity symptoms. A novel member of the cation diffusion facilitator (CDF) protein family, an A. halleri metal tolerance protein 1 (MTP1), and the homologous A. thaliana Zn transporter (ZAT)/AtMTP1 metal-specifically complement the zinc hypersensitivity of a Saccharomyces cerevisiae zrc1 cot1 mutant strain. A fusion of the AhMTP1 protein to green fluorescent protein (GFP) localizes to the vacuolar membrane of A. thaliana protoplasts. When compared with A. lyrata and A. thaliana, the total MTP1 transcript levels are substantially higher in the leaves and upregulated upon exposure to high zinc concentrations in the roots of A. halleri. The high MTP1 transcript levels in A. halleri can be primarily attributed to two genetically unlinked genomic AhMTP1 gene copies. The two corresponding loci co-segregate with zinc tolerance in the back-cross 1 generation of a cross between the zinc-tolerant species A. halleri and the zinc-sensitive species A. lyrata. In contrast, a third MTP1 gene in the genome of A. halleri generates only minor amounts of MTP1 transcripts and does not co-segregate with zinc tolerance. Our data suggests that zinc tolerance in A. halleri involves an expanded copy number of an ancestral MTP1 gene, encoding functional proteins that mediate the detoxification of zinc in the cell vacuole. At the transcript level, MTP1 gene copies of A. halleri are regulated differentially and in response to changes in zinc supply.

Amino Acid Sequence↗
PubMed1991

Purification and characterization of a third cytosolic component of the superoxide-generating NADPH oxidase of macrophages.

Activation of the superoxide (O2-)-generating NADPH oxidase of phagocytes in a cell-free system by anionic amphiphiles requires the participation of both membrane and cytosolic components. We reported that ammonium sulfate fractionation (Pick, E., Kroizman, T., and Abo, A. (1989) J. Immunol. 143, 4180-4187) and affinity chromatography on 2',5'-ADP-agarose (Shaag, D., and Pick, E. (1990) Biochim. Biophys. Acta 1037, 405-412) permit separation of cytosol in two fractions (sigma 1 and sigma 2) that support O2- production by solubilized membrane synergistically. We now describe the purification of sigma 1 to near homogeneity and demonstrate that it represents a cytosolic component distinct from p47-phox and p67-phox, that are both found in fraction sigma 2. Sigma 1 was absolutely required for the full expression of amphiphile-activated NADPH-oxidase activity. This requirement was evident whether sigma 1 was added to cell-free systems composed of: (a) solubilized membrane and a sigma 2-enriched cytosolic fraction, or (b) purified cytochrome b559, incorporated in liposomes, and purified sigma 2. Sigma 1 was purified by a sequence comprising ammonium sulfate fractionation, hydrophobic chromatography on phenyl-Superose, absorption with CM-Sepharose, anion exchange chromatography on DEAE-Sepharose, and gel filtration on Superose 12. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis analysis of sigma 1 of maximal purity, under both reducing and nonreducing conditions, demonstrated the presence of two proteins, of 24 and 22 kDa. On gel filtration, sigma 1 was eluted as a symmetrical peak of 46 kDa that by sodium dodecyl sulfate-polyacrylamide gel electrophoresis analysis revealed the presence of both 24- and 22-kDa bands. We suggest that, in its native form, sigma 1 might represent a complex of the 24- and 22-kDa proteins. The specific roles of each molecule in NADPH oxidase function remain to be determined.

Animals↗
PubMed1992

Alanine glyoxylate aminotransferase deficiency: biochemical and molecular genetic lessons from the study of a human disease.

The decision to treat a patient with primary hyperoxaluria type 1 (PHI) by combined liver and kidney transplantation, the former to correct the metabolic lesion which was then thought to be deficiency of cytoplasmic 2-oxoglutarate:glyoxylate carboligase, and the latter to replace the organ which is destroyed, provided an opportunity to investigate the disease by modern biochemical methods. It was shown that 2-oxoglutarate:glyoxylate carboligase (the first decarboxylating component of 2-oxoglutarate dehydrogenase) is entirely mitochondrial so that deficiency of a cytoplasmic form of this enzyme could not be the cause of PHI. The deficient enzyme proved to be hepatic peroxisomal alanine:glyoxylate aminotransferase (AGT). The disease can be diagnosed enzymologically on percutaneous liver biopsies and this is possible for the fetus in utero. There are four types of genetically determined heterogeneity in PHI:(1) responsiveness and non-responsiveness to pharmacological doses of pyridoxine, in terms of an effect on the rate of oxalate production; (2) the presence or absence of residual catalytic AGT activity; (3) CRM+ and CRM-variants; (4) locational variation by virtue of which the enzyme (AGT) is mitochondrial and not peroxisomal. About one third of patients with PHI have residual AGT activity and at least a large proportion of these have mitochondrial and not peroxisomal AGT. The molecular features which guide peroxisomal and mitochondrial enzymes from their sites of synthesis into the appropriate organelle are reviewed and the possibilities for genetic variation in the relevant parts of the AGT molecule are discussed. The gene directing the synthesis of AGT has been cloned and sequenced, as has the AGT cDNA from a patient with mitochondrial AGT. Three point mutations causing amino acid substitution in the predicted AGT protein sequence have been identified: proline----leucine at residue 11, glycine----arginine at residue 170 and isoleucine----methionine at residue 340. The present evidence based on screening PHI patients and control subjects suggest that the substitution at residue 11, which cosegregates with that at residue 340, generates an amphiphilic alpha-helix which resembles mitochondrial targeting sequences but that misrouting of all the newly synthesized AGT into mitochondria requires the substitution at residue 170 which may act by impeding the entry of the enzyme into peroxisomes. The recognition of enzyme locational heterogeneity in PHI due to mutations affecting leader sequences should encourage a search for similar metabolic lesions in other inborn errors of metabolism affecting peroxisomal and/or mitochondrial enzymes.

Alanine Transaminase↗
PubMed2006

Incidence and management of side effects associated with aromatase inhibitors in the adjuvant treatment of breast cancer in postmenopausal women.

OBJECTIVE: Third-generation aromatase inhibitors (AIs) are effective and generally well-tolerated as adjuvant therapy. These AIs are now being introduced for the adjuvant treatment of postmenopausal patients with estrogen-receptor-positive early-stage breast cancer. However, questions remain about their long-term safety. This paper summarizes the adverse events reported in third-generation AI trials and comments on the appropriate management of these drug-induced adverse events in patients. METHODS: Papers relating to anastrozole, exemestane, and letrozole were identified through Medline searches, and proceedings of recent oncology meetings were also reviewed to capture relevant emerging data. RESULTS: The most commonly reported adverse events associated with adjuvant AI therapy include hot flushes and musculoskeletal complaints/arthralgia. The incidence of endometrial cancer and thromboembolic events is significantly lower with an AI than with tamoxifen. However, there is a small but significant increase in the risk of osteoporosis and fractures with AI therapy. A potential negative effect on the cardiovascular system, specifically on lipid metabolism, has not been conclusively demonstrated. No significant differences in overall quality of life were observed in studies comparing AIs with tamoxifen or placebo. CONCLUSION: AIs alone and sequenced after tamoxifen are an appropriate option for adjuvant endocrine therapy for most postmenopausal patients with hormone-responsive breast cancer. The incidence of some side effects such as endometrial cancer, stroke, or pulmonary embolism associated with tamoxifen is decreased. Monitoring and management of bone loss associated with AI treatment are essential and are being addressed in ongoing trials. Further studies with longer follow-up are required to clarify the effects of AIs on lipid metabolism and cardiovascular health.

Antineoplastic Agents, Hormonal↗
PubMed2000

[Diagnosis and biological surveillance of hepatitis C virus infections].

HCV-specific laboratory assays are broadly used to establish the diagnosis, to survey viral replication and to monitor anti-viral treatments. Third-generation ELISA's have an excellent sensitivity well adapted to the early diagnosis. Positive or dubious screening tests must be controlled on a second blood sample. We recommend the use of an immunoblot assay for this control. Regular survey of the immunoblot profile may facilitate the identification of recent infections and help distinguish between active or resolutive infections. PCR assays which detect HCV ARN in serum are very usefull to decide and monitor anti-viral treatments. Their cut-off is usually in the range of 100 genomes/mL. Quantitative assays to measure viral load may also rely on PCR technology or be based on the so-called "branched DNA" technology slightly less sensitive. Genotyping or serotyping of HCV is crucial to adapt specific treatment protocols to the less responsive genotypes 1a et 1b. Cloning and sequencing of HCV isolates is necessary to explore nosocomial clusters of infections or intra-familial cases.

Antiviral Agents↗
PubMed1991

Gene organization of the human high affinity receptor for IgG, Fc gamma RI (CD64). Characterization and evidence for a second gene.

We have isolated, characterized, and sequenced the gene coding for the 72-kDa human high affinity IgG FcR, hFc gamma RI. It consists of six exons and spans 9.4 kilobase pairs. The leader sequence is encoded by two exons, the second of which is 21 base pairs long and contains the predicted site of peptidase cleavage. The third, fourth, and fifth exons each encode homologous Ig-like extracellular domains. The hydrophobic transmembrane region and a highly charged cytoplasmic tail are encoded by a single final exon. The sequence of the 5'-flanking region was determined. Two major transcription initiation sites were identified by RNase protection. The first, more downstream site was confirmed by primer extension studies; canonical CAAT and TATA boxes are located in appropriate positions upstream from this site. The second transcription initiation site was utilized only in RNA from cells incubated with gamma-interferon. This site initiates transcription upstream from the first major site. These data are consistent with the finding of two species of mRNA for hFc gamma RI in myeloid cells that are upregulated when cultured with gamma-interferon. Southern analysis of genomic DNA confirms the restriction map generated from the cloned DNA. One additional HindIII fragment was observed in genomic DNA from 13 randomly selected individuals that was not present in the phage clone used to characterize the gene. This observation suggests the existence of a second hFc gamma RI gene which lacks one of the two internal HindIII sites rather than a restriction fragment length polymorphism.

Amino Acid Sequence↗
PubMed1988

A discontinuous factor H binding site in the third component of complement as delineated by synthetic peptides.

Factor H, a very important regulator of alternative pathway activation, exerts its effects by binding to the third component complement, C3. In this study we present evidence that factor H reacts with at least two sites in the third component of complement (C3), and we have mapped one of these sites within the C3d fragment of C3. By using direct binding assays of an anti-human H anti-idiotypic antibody (alpha alpha H) and of H to C3 fragments, it was shown that both bound to the C3b and C3d (but not to C3c) fragments of C3. Cleavage of C3d by CNBr generated two major fragments with Mr values of 12,500 (residues 997-1107) and 8,600 (residues 1178-1252). Binding studies with these two fragments showed that only the Mr 8,600 fragment bound to both H and alpha alpha H. Several synthetic peptides (A58, 1192-1249; P28, 1187-1214; P16, 1194-1209; P14, 1201-1214; B17, 1206-1222; J28, 1222-1249; and J16, 1234-1249) were synthesized according to the primary sequence of the Mr 8,600 fragment. Based on the differential binding of these synthetic peptides to H, their inhibitory effect on H binding to C3b or C3d, and their effect on H cofactor activity, we mapped the H binding site in C3 to a discontinuous site spanning residues 1187-1249 of the C3 sequence. By studying the inhibition of H binding to C3b or C3d by the different synthetic peptides, we also present evidence that a second binding site in C3b for H exists.

Amino Acid Sequence↗
PubMed1996

Effects of carboxy-terminal truncation on human lecithin:cholesterol acyltransferase activity.

Mutagenesis was carried out in human lecithin:cholesterol acyltransferase (LCAT) to generate mutants with stop codons at positions corresponding to amino acids 315, 341, 359, 375, 388, 394, and 398 of the 416-amino acid sequence of the mature enzyme protein. Deletion of the 18 terminal amino acids of the protein was without effect on LCAT phospholipase or acyltransferase activity, or the stability of the protein to denaturation at 37 degrees C. Further deletion led to loss of most of the activity, associated with a 10-fold increase in the rate of denaturation at 37 degrees C. These data indicate that the proline-rich C-terminus of LCAT is not required for effective enzyme activity. The loss of activity that accompanied deletion of residues 394-398 suggests a structural role for these residues, part of a series of predicted beta-sheet sequences in the C-terminal third of the LCAT primary sequence.

Animals↗
PubMed2005

Putative outer membrane autotransporter protein influences survival of Brucella suis in BALB/c mice.

In Gram-negative bacteria, autotransporters are secreted proteins able to translocate themselves through the inner- and outer-membranes to the cell surface or to the extracellular environment. The influence of the putative outer membrane autotransporter (OmaA) protein to the persistence of Brucella suis was investigated. Sequence analyses revealed that the OmaA protein of B. suis strain 1330 consists of a signal peptide, a passenger alpha-domain, and a transporter beta-domain, which are the characteristic components of an autotransporter protein. The transporter beta-domain consists of 14 individual amphipathic beta-strands, and a 46-amino acid long alpha-helix lies upstream of the transporter domain, indicating that the B. suis OmaA is a type-I classical autotransporter. BLAST search and phylogenetic analyses revealed that the B. suis OmaA protein shares more similarities with adhesin autotransporter proteins than with protease autotransporter proteins of other bacteria. An OmaA-deficient strain (1330DeltaomaA) was generated by disrupting the DNA region encoding the passenger alpha-domain of the OmaA protein of B. suis wild type strain 1330. The omaA gene encoding the full-length OmaA protein was cloned and used to complement the OmaA-deficient strain. The OmaA-deficient strain did not differ from the wild type strain in terms of persistence in J774 macrophage cell line 24 and 48 h after inoculation, or clearance from the spleens of BALB/c mice at 1 week after intraperitoneal inoculation. These observations suggest that the function of the OmaA protein is dispensable during the acute phase of B. suis infection. However, the OmaA-deficient strain was cleared from the spleens of BALB/c mice faster than the wild type strain between the third and the ninth week after intraperitoneal inoculation, indicating that the OmaA may be important during the chronic phase of B. suis infection. Relative to the BALB/c mice injected with saline, those vaccinated with the OmaA-deficient strain exhibited 3.0-3.9log10 colony forming units protection against a challenge with B. suis strain 1330. This study is the first report correlating an autotransporter protein deficiency with persistence of B. suis in vitro and in vivo.

Animals↗
PubMed2004

Mapping the presence of Wolbachia pipientis on the phylogeny of filarial nematodes: evidence for symbiont loss during evolution.

Wolbachia pipientis is a bacterial endosymbiont associated with arthropods and filarial nematodes. In filarial nematodes, W. pipientis has been shown to play an important role in the biology of the host and in the immuno-pathology of filariasis. Several species of filariae, including the most important parasites of humans and animals (e.g. Onchocerca volvulus, Wuchereria bancrofti and Dirofilaria immitis) have been shown to harbour these bacteria. Other filarial species, including an important rodent species (Acanthocheilonema viteae), which has been used as a model for the study of filariasis, do not appear to harbour these symbionts. There are still several open questions about the distribution of W. pipientis in filarial nematodes. Firstly the number of species examined is still limited. Secondly, it is not clear whether the absence of W. pipientis in negative species could represent an ancestral characteristic or the result of a secondary loss. Thirdly, several aspects of the phylogeny of filarial nematodes are still unclear and it is thus difficult to overlay the presence/absence of W. pipientis on a tree representing filarial evolution. Here we present the results of a PCR screening for W. pipientis in 16 species of filariae and related nematodes, representing different families/subfamilies. Evidence for the presence of W. pipientis is reported for five species examined for the first time (representing the genera Litomosoides, Litomosa and Dipetalonema); original results on the absence of this bacterium are reported for nine species; for the remaining two species, we have confirmed the absence of W. pipientis recently reported by other authors. In the positive species, the infecting W. pipientis bacteria have been identified through 16S rDNA gene sequence analysis. In addition to the screening for W. pipientis in 16 species, we have generated phylogenetic reconstructions based on mitochondrial gene sequences (12S rDNA; COI), including a total of 28 filarial species and related spirurid nematodes. The mapping of the presence/absence of W. pipientis on the trees generated indicates that these bacteria have possibly been lost during evolution along some lineages of filarial nematodes.

Animals↗