Search PubMed⌕ Search

Biomedical subjects

P De Marco

Publications and source records attributed to P De Marco.

At least 19 recordsLinked to original sources
PubMed2005

Isolation and characterization of polymeric galloyl-ester-degrading bacteria from a tannery discharge place.

The culturable bacteria colonizing the rhizosphere of plants growing in the area of discharge of a tannery effluent were characterized. Relative proportions of aerobic, denitrifying, and sulfate-reducing bacteria were determined in the rhizosphere of Typha latifolia, Canna indica, and Phragmites australis. Aerobic bacteria were observed to be the most abundant group in the rhizosphere, and plant type did not seem to influence the abundance of the bacterial types analyzed. To isolate bacteria able to degrade polyphenols used in the tannery industry, enrichments were conducted under different conditions. Bacterial cultures were enriched with individual polyphenols (tannins Tara, Quebracho, or Mimosa) or with an undefined mixture of tannins present in the tannery effluent as carbon source. Cultures enriched with the effluent or Tara tannin were able to degrade tannic acid. Six bacterial isolates purified from these mixed cultures were able to use tannic acid as a sole carbon source in axenic culture. On the basis of 16S ribosomal DNA sequence analysis, these isolates were closely related to organisms belonging to the taxa Serratia, Stenotrophomonas maltophilia, Klebsiella oxytoca, Herbaspirillum chlorophenolicum, and Pseudomonas putida.

Bacteria↗
PubMed2005

Long-term performance and microbial dynamics of an up-flow fixed bed reactor established for the biodegradation of fluorobenzene.

An up-flow fixed bed reactor (UFBR) was established to investigate the biodegradation of fluorobenzene (FB) under a number of operating conditions, which included variation in the concentration of FB in the feed stream (up to 180 mg l(-1)) and temporary suspension of feeding. Degradation of FB was followed for a period of 8 months under a continuous flow regime. During the operation of the UFBR, FB was never detected in the reactor effluent, being biodegraded by the microbial biofilm or adsorbed to the granular activated carbon (GAC). Biodegradation of FB was observed from the beginning of the reactor operation, and overall, it accounted for 50% of the total amount fed to the bioreactor. High organic loads of FB (210-260 mg d(-1) dm(-3)) were found to affect the biological removal efficiency, possibly due to an inhibitory effect caused by the higher FB concentrations fed to the bioreactor (149-179 mg l(-1)). When FB feeding was suspended for 1 month, biodegradation continued, indicating that the adsorbed FB became bioavailable. Biofilm bacterial dynamics were followed throughout the UFBR operation by denaturing gradient gel electrophoresis and plate-counting techniques, showing that a quite stable community was found in the bioreactor, and this was mainly attributed to the high selective pressure exerted by the presence of FB.

Biofilms↗
PubMed2005

Empirical diversity indices applied to forest communities in different successional stages.

In this paper we examine the precision of six diversity indices, four of them empirical when including in their formulae climax adaptation numbers. These numbers define the succession position of the plant species in five forest areas in Sao Paulo State. We simulated hypothetical forests and compared the results with a list of species in the five areas. Low agreement was found among the indices in succession stages. Including the climax adaptation numbers increased precision for only some indices.

Adaptation, Physiological↗
PubMed2005

Isolation and properties of a pure bacterial strain capable of fluorobenzene degradation as sole carbon and energy source.

A pure bacterial strain capable of aerobic biodegradation of fluorobenzene (FB) as the sole carbon and energy source was isolated by selective enrichment from sediments collected from a polluted site. 16S rRNA and fatty acid analyses support that strain F11 belongs to a novel genus within the alpha-2 subgroup of the Proteobacteria, possibly within a new clade related to the order Rhizobiales. In batch cultures, growth of strain F11 on FB led to stoichiometric release of fluoride ion. Maximum experimental growth rate of 0.04 h-1 was obtained at FB concentration of 0.4 mM. Growth kinetics were described by the Luong model. An inhibitory effect with increasing FB concentrations was observed, with no growth occurring at concentrations higher than 3.9 mM. Strain F11 was shown to be able to use a range of other organic compounds, including other fluorinated compounds such as 2-fluorobenzoate, 4-fluorobenzoate and 4-fluorophenol. To our knowledge, this is the first time biodegradation of FB, as the sole carbon and energy source, by a pure bacterium has been reported.

Aerobiosis↗
PubMed2002

Isolation and initial characterization of a bacterial consortium able to mineralize fluorobenzene.

Fluorinated compounds are known to be more resistant to microbial degradation than other halogenated chemicals. A microbial consortium capable of aerobic biodegradation of fluorobenzene (FB) as the sole source of carbon and energy was isolated by selective enrichment from sediments collected in a drain near an industrial site. A combination of three microbial strains recovered from the enriched consortium was shown to be necessary for complete FB mineralization. Two of the strains (F1 and F3) were classified by 16S rRNA analysis as belonging to the Sphingobacterium/Flavobacterium group, while the third (F4) falls in the beta-Proteobacteria group, clustering with Alcaligenes species. Strain F4 was consistently found in the liquid cultures in a much greater proportion than strains F1 and F3 (86:8:6 for F4, F1, and F3, respectively). Stoichiometric release of fluoride ions was measured in batch and fed-batch cultures. In batch cultures, the consortium was able to use FB up to concentrations of 400 mg liter(-1) and was able to utilize a range of other organic compounds, including 4-fluorophenol and 4-fluorobenzoate. To our knowledge this is the first time biodegradation of FB as a sole carbon source has been reported.

Alcaligenes↗
PubMed2001

Benign familial infantile convulsions: mapping of a novel locus on chromosome 2q24 and evidence for genetic heterogeneity.

In 1997, a locus for benign familial infantile convulsions (BFIC) was mapped to chromosome 19q. Further data suggested that this locus is not involved in all families with BFIC. In the present report, we studied eight Italian families and mapped a novel BFIC locus within a 0.7-cM interval of chromosome 2q24, between markers D2S399 and D2S2330. A maximum multipoint HLOD score of 6.29 was obtained under the hypothesis of genetic heterogeneity. Furthermore, the clustering of chromosome 2q24-linked families in southern Italy may indicate a recent founder effect. In our series, 40% of the families are linked to neither chromosome 19q or 2q loci, suggesting that at least three loci are involved in BFIC. This finding is consistent with other autosomal dominant idiopathic epilepsies in which different genes were found to be implicated.

Chromosome Mapping↗
PubMed2001

Crenarchaeota and Euryarchaeota in temperate estuarine sediments.

AIMS: Application of molecular techniques to ecological studies has unveiled a wide diversity of micro-organisms in natural communities, previously unknown to microbial ecologists. New lineages of Archaea were retrieved from several non-extreme environments, showing that these micro-organisms are present in a large variety of ecosystems. The aim was therefore to assess the presence and diversity of Archaea in the sediments of the river Douro estuary (Portugal), relating the results obtained to ecological data. METHODS AND RESULTS: Total DNA was extracted from sediment samples obtained from an estuary deprived of vegetation, amplified by PCR and the resulting DNA fragments cloned. The archaeal origin of the cloned inserts was checked by Southern blot, dot blot or colony blot hybridization. Recombinant plasmids were further analysed by restriction with AvaII and selected for sequencing. Phylogenetic analyses of 14 sequences revealed the presence of members of the domain Archaea. Most of the sequences could be assigned to the kingdom Crenarchaeota. CONCLUSION: Most of these sequences were closely related to those obtained from non-extreme Crenarchaeota members previously retrieved from diverse ecosystems, such as freshwater and marine environments. SIGNIFICANCE AND IMPACT OF THE STUDY: The presence of archaeal 16S rDNA sequences in temperate estuarine sediments emerges as a valuable contribution to the understanding of the complexity of the ecosystem.

Cloning, Molecular↗
PubMed2001

Polymorphisms in genes involved in folate metabolism as risk factors for NTDs.

Moderate hyperhomocysteinemia in pregnant women has been associated with an increased risk of neural tube defects (NTDs). Periconceptional supplementation with multi-vitamins containing folic acid may normalize homocysteine metabolism and decrease the NTD risk. The C677 T variant of the MTHFR gene coding for a thermolabile enzyme has been described as the first genetic risk factor that accounts for a group of NTDs characterized by low maternal folate status and high homocysteine concentrations. Another common mutation of the same MTHFR gene, A1298 C, has also been described as an NTD risk factor. In addition to abnormal folate metabolism, anything that compromises the internalization of folate into the cell may be involved in the pathogenesis of NTDs. For this reason, a common polymorphism in the RFC-1 gene encoding the reduced folate carrier protein (A80 G) could also be an additional NTD risk factor. In the present study we examined the genotypic distributions and the allele frequencies of MTHFR A1298 C and RFC-1 A80 G polymorphisms in DNA samples from healthy Italian individuals and compared them to the frequencies observed in NTD cases and their parents. By means of restriction enzymatic analysis, we determined that the frequency of the mutated C allele of the A1298 C mutation was 0.25 among control individuals, which is in the range of that recently reported in other ethnic groups. However, we report that the mutant C allele frequencies are significantly higher among NTD cases and case mothers than among controls (0.39, 0.44, 0.25). Furthermore, for the RFC-1 A80 G mutation, we found that the frequency of the G allele of the RFC-1 mutation was 0.46 in the control population, suggesting that this is a common polymorphism in the Italian population. In spite of the high prevalence of the 80 G/G genotype among healthy subjects, we observed an increased frequency of the G allele in NTD-affected children, and their mothers and fathers. These preliminary results indicate that both the MTHFR and RFC-1 polymorphisms may play a role in NTD risk, at least in the Italian population. Further studies should be directed toward the evaluation of the level of risk conferred by the mutant MTHFR and RFC-1 genotypes, as well as the interaction between these genetic determinants and other nutritional and environmental factors.

Adult↗
PubMed2000

Folate pathway gene alterations in patients with neural tube defects.

Periconceptional folate supplementation reduces the recurrence and occurrence risk of neural tube defects (NTD) by as much as 70%, yet the protective mechanism remains unknown. Inborn errors of folate and homocysteine metabolism may be involved in the aetiology of NTDs. Previous studies have demonstrated that both homozygosity for the C677T mutation in the methylenetetrahydrofolate reductase (MTHFR) gene, and combined heterozygosity for the C677T and for another mutation in the same gene, the A1298C polymorphism, represent genetic risk factors for NTDs. In an attempt to identify additional folate related genes that contribute to NTD pathogenesis, we performed molecular genetic analysis of folate receptors (FRs). We identified 4 unrelated patients out of 50 with de novo insertions of pseudogene (PS)-specific mutations in exon 7 and 3'UTR of the FRalpha gene, arising by microconversion events. All of the substitutions affect the carboxy-terminal amino acid membrane tail, or the GPI anchor region of the nascent protein. Furthermore, among 150 control individuals, we also identified one infant with a gene conversion event within the FRalpha coding region. This study, though preliminary, provides the first genetic association between molecular variations of the FRalpha gene and NTDs and suggests that this gene can act as a risk factor for human NTD.

3' Untranslated Regions↗
PubMed2000

Isolation and characterization of two new methanesulfonic acid-degrading bacterial isolates from a Portuguese soil sample.

Two novel bacterial strains that can utilize methanesulfonic acid as a source of carbon and energy were isolated from a soil sample collected in northern Portugal. Morphological, physiological, biochemical and molecular biological characterization of the two isolates indicate that strain P1 is a pink-pigmented facultative methylotroph belonging to the genus Methylobacterium, while strain P2 is a restricted methylotroph belonging to the genus Hyphomicrobium. Both strains are strictly aerobic, degrade methanesulfonate, and release small quantities of sulfite into the medium. Growth on methanesulfonate induces a specific polypeptide profile in each strain. This, together with the positive hybridization to a DNA probe that carries the msm genes of Methylosulfonomonas methylovora strain M2, strongly endorses the contention that a methanesulfonic acid monooxygenase related to that found in the previously known methanesulfonate-utilizing bacteria is present in strains P1 and P2. The isolation of bacteria containing conserved msm genes from diverse environments and geographical locations supports the hypothesis that a common enzyme may be globally responsible for the oxidation of methanesulfonate by natural methylotrophic communities.

Alphaproteobacteria↗
PubMed1999

No evidence of a major locus for benign familial infantile convulsions on chromosome 19q12-q13.1.

PURPOSE: A locus for benign familial convulsions (BFICs) has been recently mapped on chromosome 19q12-13.1 by studying five families of Italian descent. The main goal of this study was to investigate the role of this locus in a set of seven newly identified families with at least three affected cases. METHODS: Five polymorphic microsatellite markers covering the BFIC locus on chromosome 19q have been typed, and parametric linkage analysis has been performed to analyze the segregation of the BFIC locus within our families. RESULTS: Cumulative 2-point lod scores and multipoint analysis showed no evidence of linkage between chromosome 19 markers and the BFIC phenotype. The analysis of family-specific 2-point lod scores and haplotypes, however, indicated the presence of linkage to chromosome 19q in a single family, suggesting genetic heterogeneity within our family sample. CONCLUSIONS: Our study demonstrates that the previously reported BFIC locus on chromosome 19q12-13.1 is not a major locus for BFICs. We suggest that genetic heterogeneity may have generated our discordant linkage findings, as it was reported in benign familial neonatal convulsions, a related idiopathic mendelian syndrome.

Chromosome Mapping↗
PubMed1999

Tactile evoked spikes in children.

Tactile evoked spikes (TES) are a well known EEG feature in children. We reviewed our previous studies concerning this phenomenon, with special reference to the influence of sleep and stimulation rate, the relation with middle-long latency somatosensory evoked potentials (MLSEP) and the relation between TES and spontaneous spikes in the same individual. New data were obtained by re-evaluating 566 children with TES, by assessing MLSEP from each finger, in 15 subjects with TES, and by studying MLSEP following posterior tibial nerve stimulation in 12 children with TES. TES appear to be enlarged components of MLSEP which are present in some children aged 4 to 14 years; they tend to increase during NREM sleep and to decrease during REM sleep; Their amplitude decreases at stimulation rates above 3 Hz. TES are associated with an increased risk of epileptic seizures, which usually have a benign prognosis. The possible neurophysiological mechanisms underlying this phenomenon are discussed.

Adolescent↗
PubMed1997

Methylosulfonomonas methylovora gen. nov., sp. nov., and Marinosulfonomonas methylotropha gen. nov., sp. nov.: novel methylotrophs able to grow on methanesulfonic acid.

Two novel genera of restricted facultative methylotrophs are described; both Methylosulfonomonas and Marinosulfonomonas are unique in being able to grow on methanesulfonic acid as their sole source of carbon and energy. Five identical strains of Methylosulfonomonas were isolated from diverse soil samples in England and were shown to differ in their morphology, physiology, DNA base composition, molecular genetics, and 16S rDNA sequences from the two marine strains of Marinosulfonomonas, which were isolated from British coastal waters. The marine strains were almost indistinguishable from each other and are considered to be strains of one species. Type species of each genus have been identified and named Methylosulfonomonas methylovora (strain M2) and Marinosulfonomonas methylotropha (strain PSCH4). Phylogenetic analysis using 16S rDNA sequencing places both genera in the alpha-Proteobacteria. Methylosulfonomonas is a discrete lineage within the alpha-2 subgroup and is not related closely to any other known bacterial genus. The Marinosulfonomonas strains form a monophyletic cluster in the alpha-3 subgroup of the Proteobacteria with Roseobacter spp. and some other partially characterized marine bacteria, but they are distinct from these at the genus level. This work shows that the isolation of bacteria with a unique biochemical character, the ability to grow on methanesulfonic acid as energy and carbon substrate, has resulted in the identification of two novel genera of methylotrophs that are unrelated to any other extant methylotroph genera.

Bacteria↗
PubMed1997

Median nerve middle-long latency somatosensory evoked potentials in children with tactile evoked spikes.

It is known that hand tapping during electroencephalography (EEG) recording evokes centrotemporal spikes in some 4- to 12-year-old children. This phenomenon occurs in both healthy and epileptic children. The same children were reported to show giant middle-long latency evoked potentials (MLSEPs). To study the relationship between tactile evoked spikes (TES) and MLSEPs, we performed a neurophysiologic investigation in 25 children with TES and in 25 children without any EEG abnormality. Such an investigation included a MLSEP study after both electrical and tactile stimulation with simultaneous recording of digital EEG. MLSEPs consistently showed three negative (NI, NII, NIII) and two positive (PI, PII) peaks. Children with TES had MLSEPs of enlarged amplitude. The analysis of MLSEPs and TES characteristics led us to the conclusion that they are the same neurophysiologic event, with NII being the evoked spike and NIII the following slow-wave.

Adolescent↗
PubMed1997

Purification and molecular characterization of the electron transfer protein of methanesulfonic acid monooxygenase.

A novel serine pathway methylotroph, strain M2, capable of utilizing methanesulfonic acid (MSA) as a sole source of carbon and energy was investigated. The initial step in the biodegradative pathway of MSA in strain M2 involved an inducible NADH-specific monooxygenase enzyme (MSAMO). Fractionation of MSAMO active cell extracts by ion-exchange chromatography led to the loss of MSAMO activity. Activity was restored by mixing three distinct protein fractions, designated A, B, and C. Further purification to homogeneity of component C indicated that the polypeptide was acidic, with a pI of 3.9, and contained an iron-sulfur center with spectral characteristics similar to those of other proteins containing Rieske [2Fe-2S] centers. The size of the protein subunit and the similarity of the N-terminal sequence to those of ferredoxin components of other oxygenase enzymes have suggested that component C is a specific electron transfer protein of the MSAMO which contains a Rieske [2Fe-2S] cluster. The gene encoding component C of MSAMO was cloned and sequenced, and the predicted protein sequence was compared with those of other Rieske [2Fe-2S]-center-containing ferredoxins. MSAMO appears to be a novel combination of oxygenase elements in which an enzyme related to aromatic-ring dioxygenases attacks a one-carbon (C1) compound via monooxygenation.

Amino Acid Sequence↗
PubMed1996

Schizencephaly: surgical features and new molecular genetic results.

Schizencephaly is a rare developmental disorder characterized by a full thickness cleft within the cerebral hemispheres. Large portions of the cerebral hemispheres may be missing and are replaced by cerebrospinal fluid (CSF). The walls of the clefts are lined by polymicrogyric grey matter and are covered by the so-called "pialependymal seam". The cleft may be unilateral or bilateral, and if bilateral are fairly symmetrical. Their dimensions can be small or large. The clinical features may vary from a normal to a severe development delay. 13 patients with this anomaly have been evaluated. Using SSCP (single strand conformation polymorphism) analysis, as previously described (2), they were found to have a mutant homeobox gene, Emx2.

Abnormalities, Multiple↗