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M Pérez-Alonso

Publications and source records attributed to M Pérez-Alonso.

13 recordsLinked to original sources
PubMed2005

On-line FT-Raman and dispersive Raman spectra database of artists' materials (e-VISART database).

Raman spectroscopy has been widely applied in the analysis of different types of artwork. This technique is sensitive, reliable, non-destructive and can be used in situ. However, there are few references in the literature regarding specific Raman spectra libraries for the field of artwork analysis. In this paper, the development of two on-line databases with Fourier transform Raman (FT-Raman; 1064 nm) and dispersive Raman (785 nm) spectra of materials used in fine art is presented; both are implemented in the e-vibrational spectroscopic databases of artists' materials database (e-VISART). The database provides not only spectra, but also information about each pigment. It must be highlighted that for each pigment or material several spectra are available from different dealers. Some of the FT-Raman spectra available in the e-VISART database have not been published until now. Some examples in which the e-VISART database has been successfully used are presented.

Journal Article↗
PubMed2004

Analysis of bulk and inorganic degradation products of stones, mortars and wall paintings by portable Raman microprobe spectroscopy.

This work reports the use of a portable Raman microprobe spectrometer for the analysis of bulk and decaying compounds in carbonaceous materials such as stones, mortars and wall paintings. The analysed stones include limestone, dolomite and carbonaceous sandstone, gypsum and calcium oxalate, both mono- and dihydrated, being the main inorganic degradation products detected. Mortars include bulk phases with pure gypsum, calcite and mixtures of both or with sand, soluble salts being the most important degradation products. The pigments detected in several wall paintings include Prussian blue, iron oxide red, iron oxide yellow, vermilion, carbon black and lead white. Three different decaying processes have been characterised in the mortars of the wall paintings: (a) a massive absorption of nitrates that reacted with calcium carbonate and promoted the unbinding of pigment grains, (b) the formation of black crusts in the vault of the presbytery and (c) the thermodecomposition of pigments due to a fire.

Journal Article↗
PubMed2004

Raman fibre optic approach to artwork dating.

Raman micro-probe spectroscopy has been applied to the analysis of a non catalogued hand-crafted wallpaper during its restoration process. The analysis has been totally non-destructive without the necessity of taking any sample. The artwork showed a great chromatic palette having been detected the presence of calcium carbonate, Prussian blue, ultramarine blue, gypsum (CaSO4.2H2O), minium (Pb3O4), vermilion (HgS), chrome orange (CaCO3), chrome yellow (PbCrO4), barium sulphate and carbon black (C). From the spectroscopic analysis the date of its manufacturing has been set between 1828 and 1830, introduction of chrome yellow and orange, as well as artificial ultramarine blue, and 1840, when continuous industrial wallpapers were extensively manufactured in Europe.

Art↗
PubMed2001

Structural and evolutionary analysis of the copia-like elements in the Arabidopsis thaliana genome.

The analysis of 460 kb of genomic sequence of Arabidopsis thaliana chromosome III allowed us to identify two new transposable elements named AtC1 and AtC2. AtC1 shows identical long terminal repeats (LTRs) and all the structural features characteristic of the copia-like active elements. AtC2 is also a full copia-like element, but a putative stop codon in the open reading frame (ORF) would produce a truncated protein. In order to identify the copia-like fraction of the A. thaliana genome, a careful computer-based analysis of the available sequences (which correspond to 92% of the genome) was performed. Approximately 300 nonredundant copia-like sequences homologous to AtC1 and AtC2 were detected, which showed an extreme heterogeneity in size and degree of conservation. This number of copies would correspond to approximately 1% of the A. thaliana genome. Seventy-one sequences were selected for further analysis, with 23 of them being full complete elements. Five corresponded to previously described ones, and the remaining ones, named AtC3 to AtC18 are new elements described in this work. Most of these elements presented a putative functional ORF, nearly identical LTRs, and the other elements necessary for retrotransposon activity. Phylogenetic trees, supported by high bootstrap values, indicated that these 23 elements could be considered separate families. In turn, these 23 families could be clustered into six major lineages, named copia I-VI. Most of the 71 analyzed sequences clustered into these six main clades. The widespread presence of these copia-like superfamilies throughout plant genomes is discussed.

Amino Acid Sequence↗
PubMed2000

ZFWD: a novel subfamily of plant proteins containing a C3H zinc finger and seven WD40 repeats.

We describe a new subfamily of WD repeat proteins characterised by the presence of a C3H zinc finger at the N-terminal part of the protein associated with seven WD40 repeats. We have identified four members of this subfamily in Arabidopsis thaliana, one of them with associated expressed sequence tags (ESTs). We have also identified homologous ESTs in rice, cotton, maize, poplar, pine tree and the ice plant. We do not observe animal homologues, suggesting that this subfamily could be specific for plants. Our data suggest an important role for these proteins. Based on the high sequence conservation within the conserved domains, we suggest that these proteins could have a regulatory function.

Amino Acid Sequence↗
PubMed1999

The Arabidopsis CBF gene family is composed of three genes encoding AP2 domain-containing proteins whose expression Is regulated by low temperature but not by abscisic acid or dehydration.

We have identified two genes from Arabidopsis that show high similarity with CBF1, a gene encoding an AP2 domain-containing transcriptional activator that binds to the low-temperature-responsive element CCGAC and induces the expression of some cold-regulated genes, increasing plant freezing tolerance. These two genes, which we have named CBF2 and CBF3, also encode proteins containing AP2 DNA-binding motifs. Furthermore, like CBF1, CBF2 and CBF3 proteins also include putative nuclear-localization signals and potential acidic activation domains. The CBF2 and CBF3 genes are linked to CBF1, constituting a cluster on the bottom arm of chromosome IV. The high level of similarity among the three CBF genes, their tandem organization, and the fact that they have the same transcriptional orientation all suggest a common origin. CBF1, CBF2, and CBF3 show identical expression patterns, being induced very rapidly by low-temperature treatment. However, in contrast to most of the cold-induced plant genes characterized, they are not responsive to abscisic acid or dehydration. Taken together, all of these data suggest that CBF2 and CBF3 may function as transcriptional activators, controlling the level of low-temperature gene expression and promoting freezing tolerance through an abscisic acid-independent pathway.

Abscisic Acid↗
PubMed1997

muscleblind, a gene required for photoreceptor differentiation in Drosophila, encodes novel nuclear Cys3His-type zinc-finger-containing proteins.

We have isolated the embryonic lethal gene muscleblind (mbl) as a suppressor of the sev-svp2 eye phenotype. Analysis of clones mutant for mbl during eye development shows that it is autonomously required for photoreceptor differentiation. Mutant cells are recruited into developing ommatidia and initiate neural differentiation, but they fail to properly differentiate as photoreceptors. Molecular analysis reveals that the mbl locus is large and complex, giving rise to multiple different proteins with common 5' sequences but different carboxy termini. Mbl proteins are nuclear and share a Cys3His zinc-finger motif which is also found in the TIS11/NUP475/TTP family of proteins and is highly conserved in vertebrates and invertebrates. Functional analysis of mbl, the observation that it also dominantly suppresses the sE-Jun(Asp) gain-of-function phenotype and the phenotypic similarity to mutants in the photoreceptor-specific glass gene suggest that mbl is a general factor required for photoreceptor differentiation.

Amino Acid Sequence↗
PubMed1992

Oligonucleotide probes detect splicing variants in situ in Drosophila embryos.

We describe a method for the in situ detection of specific splicing variants. The method is based on the use of antisense oligonucleotides designed to span splice junctions labelled with digoxigenin by terminal transferase tailing. We find that the spatial patterns of Ubx splicing variants Ia and IIa are similar in early embryos, but differ in late embryos. Variant IVa is only detected in the CNS (ps6) at stages 16 and 17. We also present evidence indicating that the first splicing event is cotranscriptional.

Alternative Splicing↗
PubMed1992

Comparative studies of Drosophila Antennapedia genes.

The Antennapedia (Antp) homeotic gene of Drosophila melanogaster controls cell fates and pattern formation in the epidermis, nervous system and mesoderm of thoracic segments. Its expression is controlled at the levels of transcription, alternative RNA splicing, polyadenylation and translation. Two nested Antp transcription units extend over 103 kb and produce sixteen different transcripts. We have compared the Antp genes of Drosophila virilis, Drosophila subobscura and D. melanogaster to determine which structural features are conserved and therefore may be important to the gene's function. The overall gene structures are similar. There are many conserved sequence blocks throughout the large introns, at least 15 kb upstream of the first promoter, and at least 3 kb downstream of the last polyadenylation site. Intron and exon sequence conservation around alternative splice sites indicates that alternative protein coding forms may also be conserved. Protein coding potential is perfectly conserved around the C-terminal homeodomain, well conserved in the N-terminal region, and more variable in the middle. The large size of the Antp gene may reflect a large number of control elements necessary for appropriate Antp protein expression. The conservation of transcript complexity suggests functional requirements for the different protein forms.

Amino Acid Sequence↗
PubMed1991

P sequences of Drosophila subobscura lack exon 3 and may encode a 66 kd repressor-like protein.

Several P homologous sequences have been cloned and sequenced from Drosophila subobscura. These sequences are located at the 85DE region of the O chromosome and at least three of them are organized in tandem. We have identified four copies which exhibit strong similarity between them. All of the isolated elements are truncated at the 5' and 3' ends. They have lost the inverted terminal repeats and exon 3, but maintain exons 0, 1 and 2. They are transcribed producing a polyadenylated RNA. The structure of these transcripts suggests that they are able to encode a 66 kd repressor-like protein, but not a functional transposase. We ask about the biological role of a potential repressor protein in this species.

Amino Acid Sequence↗
PubMed1989

Electron microscopic analysis of the E polytene chromosome of Drosophila subobscura: divisions 57, 58 and 59.

The banding pattern of the divisions 57, 58 and 59 of the E polytene chromosome of Drosophila subobscura was analyzed by electron microscopy. Using squashed and thin-sectioned polytene chromosomes, our electron microscopic results have been compared with the reference map of Kunze-Müller (Chromosoma 9, 559-570 (1958]. These divisions are rich in heavy bands, and their number and location coincide with those of the reference map. The major differences observed between our electron micrographs and the reference map have been at the level of faint bands.

Animals↗
PubMed1988

Electron microscope analysis of the E polytene chromosome of Drosophila subobscura: region 70B to 72D.

Revision of the reference map of the polytene chromosomes of Drosophila subobscura was started by means of the electron microscope. We present a map of regions 70B to 72D of the E chromosome obtained from squashed and thin-sectioned salivary glands. It was observed that the total number of bands in divisions 70B to 72D is considerably higher than those depicted in the reference map of Kunze-Mühl and Müller. Functional considerations are made of some regions that show puff structures.

Animals↗