Tjio, el indonesio que descubrió el número de nuestros cromosomas investigando en Zaragoza

1 .pdf (2 Pags.- 3 Fots.) derivado de post original en http://blogs.20minutos.es/ciencia-para-llevar-csicHace tan solo 60 años no se conocía el número exacto de cromosomas de la especie humana, dato que hoy manejamos con completa naturalidad al abordar un estudio de diagnóstico genético. No fue hasta la publicación del trabajo The Chromosome Number of Man en la revista Hereditas, el 26 de enero de 1956, cuando quedó establecido el número de 46 cromosomas.El descubrimiento, del que este año se celebra el sesenta aniversario, sentó las bases para el desarrollo de la genética clínica. Hoy podemos establecer las relaciones que hay entre las anomalías cromosómicas y ciertas enfermedades genéticas como el síndrome de Down, el síndrome de Edwards o el síndrome de Turner gracias al desarrollo y avance de la citogenética (rama de la genética que se centra en los cromosomas) que se inició en aquellos años. Tjio, autor principal del hallazgo, dirigía en los años 1948-1959 el laboratorio de citogenética de plantas en la recién creada Estación Experimental de Aula Dei (EEAD) en Zaragoza, perteneciente al Consejo Superior de Investigaciones Científicas (CSIC), y compaginaba esta actividad con estancias cortas en el laboratorio de Levan en el Instituto de Genética de la Universidad de Lund, Suecia, donde trabajaba con tejidos humanos.Peer reviewe

Proteínas desordenadas

15 Pags.- 7 Figs. Licencia Creative Commons BY-NC-SA 4.0Peer reviewe

Macromoléculas biológicas: proteínas, DNA y RNA

27 Pags.- 14 Figs. Licencia Creative Commons BY-NC-SA 4.0Peer reviewe

Macromoléculas biológicas: proteínas, DNA y RNA

27 Pags.- 14 Figs. Licencia Creative Commons BY-NC-SA 4.0Peer reviewe

Evolutionary divergence of chloroplast FAD synthetase proteins

<p>Abstract</p> <p>Background</p> <p>Flavin adenine dinucleotide synthetases (FADSs) - a group of bifunctional enzymes that carry out the dual functions of riboflavin phosphorylation to produce flavin mononucleotide (FMN) and its subsequent adenylation to generate FAD in most prokaryotes - were studied in plants in terms of sequence, structure and evolutionary history.</p> <p>Results</p> <p>Using a variety of bioinformatics methods we have found that FADS enzymes localized to the chloroplasts, which we term as plant-like FADS proteins, are distributed across a variety of green plant lineages and constitute a divergent protein family clearly of cyanobacterial origin. The <it>C</it>-terminal module of these enzymes does not contain the typical riboflavin kinase active site sequence, while the <it>N</it>-terminal module is broadly conserved. These results agree with a previous work reported by Sandoval <it>et al</it>. in 2008. Furthermore, our observations and preliminary experimental results indicate that the <it>C-</it>terminus of plant-like FADS proteins may contain a catalytic activity, but different to that of their prokaryotic counterparts. In fact, homology models predict that plant-specific conserved residues constitute a distinct active site in the <it>C</it>-terminus.</p> <p>Conclusions</p> <p>A structure-based sequence alignment and an in-depth evolutionary survey of FADS proteins, thought to be crucial in plant metabolism, are reported, which will be essential for the correct annotation of plant genomes and further structural and functional studies. This work is a contribution to our understanding of the evolutionary history of plant-like FADS enzymes, which constitute a new family of FADS proteins whose <it>C</it>-terminal module might be involved in a distinct catalytic activity.</p

Evolution of Protein Ductility in Duplicated Genes of Plants

Previous work has shown that ductile/intrinsically disordered proteins (IDPs) and residues (IDRs) are found in all unicellular and multicellular organisms, wherein they are essential for basic cellular functions and complement the function of rigid proteins. In addition, computational studies of diverse phylogenetic lineages have revealed: (1) that protein ductility increases in concert with organismic complexity, and (2) that distributions of IDPs and IDRs along the chromosomes of plant species are non-random and correlate with variations in the rates of the genetic recombination and chromosomal rearrangement. Here, we show that approximately 50% of aligned residues in paralogs across a spectrum of algae, bryophytes, monocots, and eudicots are IDRs and that a high proportion (ca. 60%) are in disordered segments greater than 30 residues. When three types of IDRs are distinguished (i.e., identical, similar and variable IDRs) we find that species with large numbers of chromosome and endoduplicated genes exhibit paralogous sequences with a higher frequency of identical IDRs, whereas species with small chromosomes numbers exhibit paralogous sequences with a higher frequency of similar and variable IDRs. These results are interpreted to indicate that genome duplication events influence the distribution of IDRs along protein sequences and likely favor the presence of identical IDRs (compared to similar IDRs or variable IDRs). We discuss the evolutionary implications of gene duplication events in the context of ductile/disordered residues and segments, their conservation, and their effects on functionality

Copper effect on cytochrome b559 of photosystem II under photoinhibitory conditions

The definitive version is available at www.blackwell-synergy.comToxic Cu(II) effect on Cytochrome b559 under aerobic photoinhibitory conditions was examined in two different PSII membrane preparations active in oxygen evolution. The preparations differ in the content of Cytochrome b559 redox potential forms. Difference absorption spectra showed that the presence of Cu(II) induced the oxidation of the high-potential form of Cytochrome b559 in the dark. Addition of hydroquinone reduced the total oxidised high-potential form of Cytochrome b559 present in Cu(II)-treated PSII membranes indicating that no conversion to the low-potential form took place. Spectroscopic determinations of Cytochrome b559 during photoinhibitory treatment showed slower kinetics of Cu(II) effect on Cytochrome b559 as compared to the rapid loss of oxygen evolution activity in the same conditions. This result indicates that Cytochrome b559 is affected after PSII centers are photoinhibited. The high-potential form was more sensitive to toxic Cu(II) action than the low-potential form under illumination at pH 6.0. The content of the high-potential form of Cytochrome b559 was completely lost, however the low-potential content was unaffected in these conditions. This loss did not involve cytochrome protein degradation. Results are discussed in terms of different binding properties of the heme iron to the protonated or unprotonated histidine ligand in the high-potential and low-potential forms of Cytochrome b559, respectively.M. Bernal was recipient of an I3P Programme fellowship from Consejo Superior de Investigaciones Científicas. This work was supported by the Dirección General de Investigación (Grant BMC2002-00031) to R.P. and Gobierno de Aragón (Grant P015/2001) to I.Y., and it has been done within GC DGA 2002 Program of Gobierno de Aragón.Peer reviewe

Mycobacterium tuberculosis Complex Exhibits Lineage-Specific Variations Affecting Protein Ductility and Epitope Recognition

The advent of whole-genome sequencing has provided an unprecedented detail about the evolution and genetic significance of species-specific variations across the whole Mycobacterium tuberculosis Complex. However, little attention has been focused on understanding the functional roles of these variations in the protein coding sequences. In this work, we compare the coding sequences from 74 sequenced mycobacterial species including M. africanum, M. bovis, M. canettii, M. caprae, M. orygis, and M. tuberculosis. Results show that albeit protein variations affect all functional classes, those proteins involved in lipid and intermediary metabolism and respiration have accumulated mutations during evolution. To understand the impact of these mutations on protein functionality, we explored their implications on protein ductility/disorder, a yet unexplored feature of mycobacterial pro-teomes. In agreement with previous studies, we found that a Gly71Ile substitution in the PhoPR virulence system severely affects the ductility of its nearby region in M. africanum and animal-adapted species. In the same line of evidence, the SmtB transcriptional regulator shows amino acid variations specific to the Beijing lineage, which affects the flexibility of the N-terminal trans-activation domain. Furthermore, despite the fact that MTBC epitopes are evolutionary hyperconserved, we identify strain-and lineag-especific amino acid mutations affecting previously known T-cell epitopes such as EsxH and FbpA (Ag85A). Interestingly, in silico studies reveal that these variations result in differential interaction of epitopes with the main HLA haplogroups.Gobierno de Aragón (DGA-GC B18 and B25), the Spanish Ministry of Science and Competitiveness (BIO2014-52580P, CSIC13-4E-2490), Instituto de Salud Carlos III (PI12/01970) and the European Commission Horizon 2020 (H2020-PHC-643381). Some of these grants were partially financed by the EU FEDER Program. This work was also supported by Fundação para a Ciência e Tecnologia, Portugal (IF/00474/2014) and cofunded by Programa Operacional Regional do Norte (ON.2—O Novo Norte), Quadro de Referência Estratégico Nacional (QREN), through the Fundo Europeu de Desenvolvimento Regional (FEDER)info:eu-repo/semantics/publishedVersio

Spin-label EPR study in thylakoid membranes from a new herbicide-resistant D1 mutant from soybean cell cultures deficient in fatty acid desaturation

El pdf del artículo es la versión post-print.Fatty acid desaturation effect on the lipid fluidity in thylakoid membranes isolated from the STR7 mutant was investigated by electron paramagnetic resonance (EPR) using spin label probes. The spectra of both 5- and 16-n-doxylstearic acid probes were measured as a function of the temperature between 10-305 K and compared to those of the wild type. This complete thermal evolution provides a wider picture of the dynamics. The spectra of the 5-n-doxylstearic acid probe were identical in both STR7 mutant and wild type thylakoids as well as their temperature evolution. However, differences were found with the 16-n-doxylstearic acid probe at temperatures between 230-305 K. The differences in the thermal evolution of the EPR spectra can be interpreted as a 5-10 K shift toward higher temperatures of the probe motional rates in the STR7 mutant as compared with that in the wild type. At temperatures below 230 K no differences were observed. The results indicated that the lipid motion in the outermost region of the thylakoids is the same in the STR7 mutant than in the wild type while the fluidity in the inner region of the STR7 mutant membrane decreases. Our data point out a picture of the STR7 thylakoid membrane in which the lipid motion is slower most probably as a consequence of fatty acid desaturation deficiency.M.A. and I.G.-R. were recipients of a contract and a fellowship, respectively, from the Ministerio de Educación y Cultura of Spain. This work was supported by the Dirección General de Investigación Científica y Técnica (Grant PB98-1632) and by the Diputación General de Aragón (Project P17/98).Peer reviewe

Photoinhibition and recovery in a herbicide-resistant mutant from Glycine max (L.) Merr. cell cultures deficient in fatty acid unsaturation

The definitive version is available at: http://www.springerlink.com/content/100484/Photoinhibition and recovery were studied in two photosynthetic cell suspensions from soybean (Glycine max L. Merr): the wild type (WT) and the herbicide-resistant D1 mutant STR7. This mutant also showed an increase in saturated fatty acids from thylakoid lipids. STR7 was more sensitive to photoinhibition under culture conditions. In vivo photoinhibition experiments in the presence of chloramphenicol, in vitro studies in isolated thylakoid membranes, and immunoblot analysis indicated that the process of light-induced degradation of the D1 protein was not involved in the response of STR7 to light. At growth temperature (24°C), the recovery rate of photoinhibited photosystem II (PSII) was slower in STR7 relative to WT. Photoinhibition and recovery were differentially affected by temperature in both cell lines. The rates of photoinhibition were faster in STR7 at any temperature below 27°C. The rates of PSII recovery from STR7 were more severely affected than those of WT at temperatures lower than 24°C. The photoinhibition and recovery rates of WT at 17°C mimicked those of STR7 at 24°C. In organelle translation studies indicated that synthesis and elongation of D1 were substantially similar in both cell lines. However, sucrose gradient fractionation of chloroplast membranes demonstrated that D1 and also other PSII proteins such as D2, OEE33, and LCHII had a reduced capability to incorporate into PSII to yield a mature assembled complex in STR7. This effect may become the rate-limiting step during the recovery of photoinhibited PSII and may explain the increased sensitivity to high light found in STR7. Our data may hint at a possible role of fatty acids from membrane lipids in the assembly and dynamics of PSII.This work was supported by the MCYT (Grants PB98-1632 and BMC2002-00031). M.A. is the recipient of a contract from MCYT (Programa Ramón y Cajal) and R.C. is the recipient of a fellowship from Gobierno de Aragón (CONSI+D-DGA).Peer reviewe