RESUMO
BACKGROUND: Glycoprotein VI (GPVI), 60-65 kDa, is a major collagen receptor on platelet membranes involved in adhesive and signaling responses. Mice lacking GPVI have impaired platelet response to collagen and defective primary adhesion and subsequent thrombus formation. Complete or partial deficiency of GPVI in humans is a rare condition presenting as a mild bleeding disorder. The defect in most of the reported patients is acquired and associated with other diseases. To date, only two patients have been characterized at the molecular level who carry different compound heterozygous mutations in the GP6 gene. OBJECTIVE: To report four unrelated patients from non-consanguineous families who presented with mucocutaneous bleeding. They had absent platelet aggregation and (14) C-5-HT secretion with collagen, convulxin and collagen-related peptide. RESULTS: Flow cytometry and immunofluorescence-confocal microscopy showed an absence of GPVI in non-permeabilized platelets. All the patients had an adenine insertion in exon 6 (c.711_712insA), changing the reading frame and generating a premature 'stop codon' in site 242 of the protein. The mutation predicts the synthesis of the truncated protein before the trans-membrane domain, corresponding to a band of ≈49 kDa observed in western blots and in permeabilized platelets by immunofluorescence. Platelet mRNA from all the patients was sequenced and contained the corresponding adenine insertion. Heterozygous relatives had no pathological bleeding, normal response to collagen and convulxin and intermediate membrane expression of GPVI. CONCLUSIONS: The identification of four unrelated homozygous patients with an identical defect suggests that inherited GPVI deficiency is more frequent than previously suspected, at least in Chile.
Assuntos
Adenina/metabolismo , Transtornos da Coagulação Sanguínea/genética , Éxons , Glicoproteínas da Membrana de Plaquetas/genética , Adulto , Sequência de Bases , Criança , Chile , Códon sem Sentido , Primers do DNA , Feminino , Heterozigoto , Humanos , Masculino , RNA Mensageiro/genética , Adulto JovemRESUMO
AIMS: To analyse the possible effect of poly-beta-hydroxyalkanoate (PHA) consumption on 2,4,6-trichlorophenol (2,4,6-TCP) degradation during starvation by Sphingopyxis chilensis S37 strain, which stores PHAs and degrades 2,4,6-TCP. METHODS AND RESULTS: The strain was inoculated in saline solution supplemented with 2,4,6-TCP (25-400 microm). Chlorophenol degradation was followed both spectrophotometrically and by chlorine released; viable bacterial counts were also determined. Cells starved for 24, 48 or 72 h were incubated with 25 microm of 2,4,6-TCP and PHA in cells investigated by spectrofluorimetric and flow cytometry. Results demonstrated that starvation decreased the ability to degrade 2,4,6-TCP. After 72 h of starvation, degradation of 2,4,6-TCP decreased to less than 10% and the relative PHA content diminished to ca 50% during the first 24 h. CONCLUSION: Utilization of PHA may be an important factor for the degradation of toxic compounds, such as 2,4,6-TCP, in bacterial strains unable to use this toxic compound as carbon and energy source. SIGNIFICANCE AND IMPACT OF THE STUDY: This is the first study describing a relationship between intracellular PHA consumption and 2,4,6-TCP degradation. Therefore, PHAs provides an endogenous carbon and energy source under starvation and can play a significant role in the degradation of toxic compounds.
Assuntos
Alphaproteobacteria/metabolismo , Clorofenóis/metabolismo , Ácidos Graxos/metabolismo , Hidroxiácidos/metabolismo , Poliésteres/metabolismo , Alphaproteobacteria/classificação , Alphaproteobacteria/genética , Biodegradação Ambiental , Cloretos/análise , Hidroxibutiratos/metabolismo , Fatores de TempoRESUMO
The aim of this work was to study the catabolic pathway of the pollutant 2,4,6-trichlorophenol in Ralstonia eutropha JMP134. 2,6-dichlorohydroquinone was detected as transient intermediate. Enzymatic transformations of 6-chlorohydroxyquinol to 2-chloromaleylacetate, and of this compound to maleylacetate were detected in crude extracts. Therefore, the degradation of 2,4,6-trichlorophenol proceeded through an hydroxyquinol pathway, different from the other chloroaromatic pathways reported in this strain. The same results were observed in two other 2,4,6-trichlorophenol degrading strains: R. eutropha JMP222, a derivative of strain JMP134 lacking the chlorocatechol catabolism-encoding pJP4 plasmid, and a river isolate, Ralstonia sp. PZK.