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J P Pinto

Publications and source records attributed to J P Pinto.

16 recordsLinked to original sources
PubMed2006

Identification of a promoter element within the zebrafish colXalpha1 gene responsive to runx2 isoforms Osf2/Cbfa1 and til-1 but not to pebp2alphaA2.

Type X collagen is a short chain collagen specifically expressed by hypertrophic chondrocytes during endochondral ossification. We report here the functional analysis of the zebrafish (Danio rerio) collagen Xalpha1 gene (colXalpha1) promoter with the identification of a region responsive to two isoforms of the runt domain transcription factor runx2. Furthermore, we provide evidence for the presence of dual promoter usage in zebrafish, a finding that should be important to further understanding of the regulation of its restricted tissue distribution and spatial-temporal expression during early development. The zebrafish colXalpha1 gene structure is comparable to that recently identified by comparative genomics in takifugu and shows homology with corresponding mammalian genes, indicating that its general architecture has been maintained throughout vertebrate evolution. Our data suggest that, as in mammals, runx2 plays a role in the development of the osteogenic lineage, supporting zebrafish as a model for studies of bone and cartilage development.

Amino Acid Sequence↗
PubMed2003

Matrix Gla protein gene expression and protein accumulation colocalize with cartilage distribution during development of the teleost fish Sparus aurata.

Matrix Gla protein (MGP) is a member of the family of extracellular mineral-binding Gla proteins, expressed in several tissues with high accumulation in bone and cartilage. Although the precise molecular mechanism of action of this protein remains unknown, all available evidence indicates that MGP plays a role as an inhibitor of mineralization. We investigated the sites of gene expression and protein accumulation of MGP throughout development of the bony fish Sparus aurata, by in situ hybridization, Northern and RT-PCR Southern hybridization, and immunohistochemistry. The results obtained were compared with the patterns of developmental appearance of cartilaginous and mineralized structures in this species, identified by histological techniques and by detection of mRNA presence and protein accumulation of osteocalcin (Bone Gla protein), a marker for osteoblasts known to accumulate in bone mineralized extracellular matrix. The expression of MGP mRNA was first detected at 2 days posthatching (dph) by Northern analysis, RT-PCR amplification, and in situ hybridization, and thereafter continuously detected at various levels of intensity, until 130 dph. In situ hybridization analysis performed in parallel with immunohistochemistry indicated that until ca. 45 dph, the MGP gene was highly expressed in a number of different tissues including skull, jaw, neural and hemal arches, and heart and the protein accumulated in cartilaginous tissues. At 85 dph, a stage when most skeletal structures are mineralized, MGP gene expression and protein accumulation were restricted to the remaining cartilaginous structures, whereas osteocalcin gene expression and protein accumulation were localized in most mineralized structures. MGP gene expression was also detected in heart and kidney, although in situ hybridization only detected MGP mRNA in heart, located in the arterial bulbus and not in the cardiac muscle. Our results are in agreement with those recently described for MGP localization in adult tissues of another teleost fish, as well as available data from higher vertebrates, strengthening the hypothesis of a conserved function for MGP from teleost fish to human, a period of more than 200 million years of evolution. In addition, Sparus aurata, a marine teleost fish routinely grown in captivity, appears to be a good model to further analyze MGP gene expression and regulation.

Amino Acid Sequence↗
PubMed2002

Cloning and characterization of the cDNA and gene encoding Xenopus laevis osteocalcin.

A full length Xenopus laevis osteocalcin (bone Gla protein, BGP) has been cloned by a combination of reverse transcription and amplification by the polymerase chain reaction, sequenced, and found to encode a polypeptide with 101 amino acid residues, including a 52-residue prepro-region and a 49-residue mature protein. The N-terminal region of the mature Xenopus BGP (xBGP), as deduced from the cDNA, is in full agreement with the sequence of the BGP previously purified from Xenopus long bones. This cDNA was used to clone the xBGP gene and its promoter region. The xBGP gene spans 3727 bp from the site of transcription initiation corresponding to the 5'end of the cDNA to the site of insertion of the poly-A(+) tail, and it contains four exons. This structure is similar to the one obtained for both fish and mammalian BGP genes and indicates that the molecular organization of this gene has been conserved throughout vertebrate evolution. Also similar to other known vertebrate systems, xBGP gene expression is restricted to bone, with no signal for xBGP messenger RNA (mRNA) detected in all other tissues analyzed. The availability of the xBGP promoter will permit to analyze its regulation in a widely used non-mammalian model system for vertebrate development, taking advantage of the availability of sequences for various Xenopus steroid hormone receptors and transcription factors known to affect BGP expression in the mammalian system.

5' Flanking Region↗
PubMed2001

Cloning of the bone Gla protein gene from the teleost fish Sparus aurata. Evidence for overall conservation in gene organization and bone-specific expression from fish to man.

Bone Gla protein (BGP, Osteocalcin) is a bone-specific vitamin K-dependent protein which has been intensively studied in mammals. Although BGP is the most abundant non-collagenous protein of bone, its mode of action at the molecular level remains unclear. From an evolutionary point of view, the appearance of BGP seems to parallel the appearance of hydroxyapatite-containing bone structures since it has never been found in elasmobranchs, whose skeleton is composed of calcified cartilage. Accordingly, recent work indicates that, in mammalian bone, BGP is required for adequate maturation of the hydroxyapatite crystal. Taken together, these data suggest that teleost fishes, presumably the first vertebrates to develop a BGP-containing skeleton, may be a useful model to further investigate BGP function. In addition, fish offer several advantages over mammalian models, due to a large progeny, external embryonic development and transparency of larvae. In the present work, the BGP cDNA and gene were cloned from a teleost fish, Sparus aurata, and its tissue distribution, pattern of developmental expression and evolutionary pathways analyzed. The molecular organization of the Sparus BGP (spBGP) gene is similar to mammalian BGP genes, and its expression throughout development follows the onset of calcification. The spBGP gene encodes a pre-propeptide of 97 amino acid residues, expressed only in bone and showing extensive homology to its mammalian homologs. Phylogenetic analysis of the available BGP sequences supports the hypothesis that all BGPs have a single origin and share a common ancestor with a related vitamin K-dependent protein (Matrix Gla protein).

Amino Acid Sequence↗
PubMed1999

Continuous processing in word recognition at 24 months.

Speech processing in adults in continuous: as acoustic-phonetic information is heard, listeners' interpretation of the speech is updated incrementally. The present studies used a visual fixation technique to examine whether young children also interpret speech continuously. In Experiments 1 and 2, 24-month-old children looked at visual displays while hearing sentences. Sentences each contained a target word labeling one of the two displayed pictures. Children's latency to fixate the labeled picture was measured. Children's responses were delayed when the competing distractor picture's label overlapped phonetically with the target at onset (dog-doll), but not when the pictures' labels rhymed (ball-doll), showing that children monitored the speech stream incrementally for acoustic-phonetic information specifying the correct picture. In Experiment 3, adults' responses in the same task were found to be very similar to those of the 24-month-olds. This research shows that by 24 months, children can interpret speech continuously.

Adult↗
PubMed1991

Isotopic exchange between carbon dioxide and ozone via O(1D) in the stratosphere.

We propose a novel mechanism for isotopic exchange between CO2 and O3 via O(1D) + CO2 --> CO3* followed by CO3* --> CO2 + O(3P). A one-dimensional model calculation shows that this mechanism can account for the enrichment in 18O in the stratospheric CO2 observed by Gamo et al. [1989], using the heavy O3 profile observed by Mauersberger [1981]. The implications of this mechanism for other stratospheric species and as a source of isotopically heavy CO2 in the troposphere are briefly discussed.

Atmosphere↗
PubMed1989

Photochemistry of CO and H2O: analysis of laboratory experiments and applications to the prebiotic Earth's atmosphere.

The role photochemical reactions in the early Earth's atmosphere played in the prebiotic synthesis of simple organic molecules was examined. We have extended an earlier calculation of formaldehyde production rates to more reduced carbon species, such as methanol, methane, and acetaldehyde. We have simulated the experimental results of Bar-Nun and Chang (1983) as an acid in the construction of our photochemical scheme and as a way of validating our model. Our results indicate that some fraction of CO2 and H2 present in the primitive atmosphere could have been converted to simple organic molecules. The exact amount is dependent on the partial pressure of CO2 and H2 in the atmosphere and on what assumptions are made concerning the shape of the absorption spectra of CO2 and H2O. In particular, the results are most sensitive to the presence or absence of absorption at wavelengths longward of 2000 angstroms. We also find that small quantities of CH4 could have been present in the prebiotic Earth's atmosphere as the result of the photoreduction of CO.

Atmosphere↗
PubMed1989

Sulfur, ultraviolet radiation, and the early evolution of life.

The present biosphere is shielded from harmful solar near ultraviolet (UV) radiation by atmospheric ozone. We suggest here that elemental sulfur vapor could have played a similar role in an anoxic, ozone-free, primitive atmosphere. Sulfur vapor would have been produced photochemically from volcanogenic SO2 and H2S. It is composed of ring molecules, primarily S8, that absorb strongly throughout the near UV, yet are expected to be relatively stable against photolysis and chemical attack. It is also insoluble in water and would thus have been immune to rainout or surface deposition over the oceans. The concentration of S8 in the primitive atmosphere would have been limited by its saturation vapor pressure, which is a strong function of temperature. Hence, it would have depended on the magnitude of the atmospheric greenhouse effect. Surface temperatures of 45 degrees C or higher, corresponding to carbon dioxide partial pressures exceeding 2 bars, are required to sustain an effective UV screen. Two additional requirements are that the ocean was saturated with sulfite and bisulfite, and that linear S8 chains must tend to reform rings faster than they are destroyed by photolysis. A warm, sulfur-rich, primitive atmosphere is consistent with inferences drawn from molecular phylogeny, which suggest that some of the earliest organisms were thermophilic bacteria that metabolized elemental sulfur.

Atmosphere↗
PubMed1988

Estimation of the reaction rate for the formation of CH3O from H + H2CO: implications for chemistry in the Solar System.

It is argued that the formation of the methoxy radical (CH3O) from H + H2CO may play an essential role in the reduction of CO to CH4. The rate coefficient for this reaction has been estimated using the approximate theory of J. Troe (1977a, J. Chem. Phys. 66, 4745) and transition state theory. We briefly discuss the implications of this reaction for the chemistry of CO on Jupiter, in the solar nebula, for interpreting the laboratory experiments of A. Bar-Nun and A. Shaviv (1975, Icarus 24, 197) and A. Bar-Nun and S. Chang (1983, J. Geophys. Res. 88, 6662) and for organic synthesis in the prebiotic terrestrial atmosphere.

Atmosphere↗
PubMed1988

HDO in the Martian atmosphere: implications for the abundance of crustal water.

The physical and chemical processes that lead to the preferential escape of hydrogen over deuterium in the Martian atmosphere are studied in detail using a one-dimensional photochemical model. Comparison of our theory with recent observations of HDO suggests that, averaged over the planet, Mars contains 0.2 m of crustal water that is exchangeable with the atmosphere. Our estimate is considerably lower than recent estimates of subsurface water on Mars based on geomorphological analysis of Viking images. The estimate can be reconciled if only a small fraction of crustal water can exchange with the atmosphere.

Atmosphere↗
PubMed1985

Oxidant abundances in rainwater and the evolution of atmospheric oxygen.

A one-dimensional photochemical model has been used to estimate the flux of dissolved hydrogen peroxide (H2O2) and of other soluble species in rainwater as a function of atmospheric oxygen level. H2O2 should have replaced O2 as the dominant oxidant in rainwater at oxygen levels below 10(-3)-10(-2) times the present atmospheric level (PAL). The exact value of pO2 at which H2O2 becomes more important than O2 depends on the abundance of trace gases such as CO, CH4, and NO. H2O2 was probably an important oxidant even in an O2-free atmosphere, provided that CO2 levels were significant higher than today's. In model atmospheres containing free O2 the concentration of photochemically produced oxidants generally exceeds that of photochemically produced reductants. The oxidizing power of rainwater is therefore greater than that due to dissolved molecular O2 alone. The difference is small at present but becomes important at O2 levels less than 10(-3) PAL. At O2 levels between 10(-4) and 10(-5) PAL the oxidizing power of rainwater is almost independent of pO2. Precambrian soils in which a part or all of the Fe2+ in their source rocks has been oxidized to Fe3+ could therefore have developed in the presence of an atmosphere with very low values of pO2. On the other hand, the upper limit for pO2 during early and mid-Precambrian time suggested by the incomplete oxidation of FeO in soils developed on basaltic rocks is affected only slightly by the presence of photochemical products in rainwater.

Atmosphere↗
PubMed1984

Photochemistry of the atmosphere of Titan: comparison between model and observations.

The photochemistry of simple molecules containing carbon, hydrogen, nitrogen, and oxygen atoms in the atmosphere of Titan has been investigated using updated chemical schemes and our own estimates of a number of key rate coefficients. Proper exospheric boundary conditions, vertical transport, and condensation processes at the tropopause have been incorporated into the model. It is argued that he composition, climatology, and evolution of Titan's atmosphere are controlled by five major processes: (a) photolysis and photosensitized dissociation of CH4; (b) conversion of H to H2 and escape of hydrogen; (c) synthesis of higher hydrocarbons; (d) coupling between nitrogen and hydrocarbons; (e) coupling between oxygen and hydrocarbons. Starting with N2, CH4, and H2O, and invoking interactions with ultraviolet sunlight, energetic electrons, and cosmic rays, the model satisfactorily accounts for the concentrations of minor species observed by the Voyager IRIS and UVS instruments. Photochemistry is responsible for converting the simpler atmospheric species into more complex organic compounds, which are subsequently condensed at the tropopause and deposited on the surface. Titan might have lost 5.6 x 10(4), 1.8 x 10(3), and 4.0 g cm-2, or the equivalent of 8, 0.25, and 5 x 10(-4) bars of CH4, N2, and CO, respectively, over geologic time. Implications of abiotic organic synthesis on Titan for the origin of life on Earth are briefly discussed.

Atmosphere↗
PubMedDate not supplied

D to H ratio and the origin and evolution of Titan's atmosphere.

A value of 1.7 x 10(-3) has been reported for the ratio of CH3D to CH4 in the stratosphere of the saturnian moon Titan. A lower value of 6 x 10(-4) for this ratio in the deeper part of Titan's atmosphere was reported by de Bergh et al. For comparison we note that the CH3D to CH4 ratio on Saturn and Jupiter is 8.7 x 10(-5) and 6.7 x 10(-5), respectively. We estimate the uncertainties in all these observations and data reduction to be about a factor of 2. Despite these uncertainties it appears that Titan's atmosphere is enriched in deuterium by a factor of > or = 3 relative to Jupiter and Saturn. Potential causative factors examined here for this enrichment are condensation to form tropospheric methane clouds, fractionation occurring over a hypothetical CH4-C2H6 ocean and between the ocean and the clathrate crust beneath, fractionation which occurred during the formation of Titan and fractionation occurring as a result of the evolution of Titan's atmosphere. We conclude that the greater part of the observed fractionation is probably derived from the formation of Titan and the subsequent evolution of Titan's atmosphere driven by photochemistry.

Deuterium↗
PubMedDate not supplied

When half a word is enough: infants can recognize spoken words using partial phonetic information.

Adults process speech incrementally, rapidly identifying spoken words on the basis of initial phonetic information sufficient to distinguish them from alternatives. In this study, infants in the second year also made use of word-initial information to understand fluent speech. The time course of comprehension was examined by tracking infants' eye movements as they looked at pictures in response to familiar spoken words, presented both as whole words in intact form and as partial words in which only the first 300 ms of the word was heard. In Experiment 1, 21-month-old infants (N = 32) recognized partial words as quickly and reliably as they recognized whole words; in Experiment 2, these findings were replicated with 18-month-old infants (N = 32). Combining the data from both experiments, efficiency in spoken word recognition was examined in relation to level of lexical development. Infants with more than 100 words in their productive vocabulary were more accurate in identifying familiar words than were infants with less than 60 words. Grouped by response speed, infants with faster mean reaction times were more accurate in word recognition and also had larger productive vocabularies than infants with slower response latencies. These results show that infants in the second year are capable of incremental speech processing even before entering the vocabulary spurt, and that lexical growth is associated with increased speed and efficiency in understanding spoken language.

Eye Movements↗