Evolución de la contaminación del aire e impacto de los programas de control en tres megaciudades de América Latina

En este trabajo se discute la problemática de la contaminación del aire en tres megaciudades de América Latina (Ciudad de México, São Paulo y Santiago); en particular se revisan los programas de control de la contaminación atmosférica que han puesto en marcha los gobiernos de esas ciudades y la evolución de los niveles de contaminantes durante el periodo 1988-1995 en Santiago de Chile y São Paulo, y hasta 1997 en la Ciudad de México, con el objeto de evaluar el impacto de esos programas. En las tres megaciudades se observó un descenso en las concentraciones de PTS, PM10, SO2, NO2, CO y O3 durante el periodo mencionado, aunque la mayoría de los contaminantes siguen rebasando la norma de calidad del aire. Cabe destacar que el mayor impacto de los programas ha sido sobre los niveles de SO2. Se recomienda el desarrollo de políticas de transporte sostenible; en ese sentido, en la Conferencia Europea de Ministros del Transporte la Organización para la Cooperación y el Desarrollo Económico (OCDE) propuso distintas estrategias. Por otra parte, la participación ciudadana es importante al tomar decisiones relacionadas con las políticas de transport

Single berry development – a new phenotyping and transcriptomics paradigm

Most present knowledge on berry development has been obtained from a random sampling of hundreds of berries to average their diversity of the experimental plot. According to recent studies, such heterogeneous samples formed from non-synchronized berries of mixed developmental stages are unsuitable for detecting fast physiological and molecular changes. Thus, it is necessary to revisit the physiological and transcriptional bases of berry ripening. Here we report the in-depth study of the late-ripening program in three genotypes. Berry expansion during the second growth phase was characterized on-vine through image analysis. Hundreds of sampled berries were individually analyzed for primary metabolites to calculate their respective accumulation rates with high precision. These primary individual fluxes and the growth kinetics allowed us to distinguish targeted developmental stages further investigated through RNA profiling. Single berry monitoring evidenced sharp developmental phases during which specific genes or pathways are quickly switched ON or OFF. The comparison between Syrah and the two microvines showed phenotypic differences in late-ripening stages in vines grown in the field (Syrah) and microvines (MV032 and MV102) grown in the greenhouse. This study shows that new high-throughput single berry phenotyping methods are required to compare unambiguous developmental stages in physiological or genetic studies

The Microvine: A Versatile Plant Model to Boost Grapevine Studies in Physiology and Genetics

The microvine is a grapevine somatic variant. The Vvgai1 mutation results in a miniaturization of the vegetative organs of the plant keeping fruit size intact and a systematic conversion of tendrils into inflorescences. The physiological characterization of the vegetative and reproductive development of the microvine makes it possible to infer kinetic data from spatial phenotypes. This biological model allows experiments on vine and grape development in tightly controlled conditions, which greatly accelerate physiology, molecular biology, as well as genetic studies. After introducing the main biological properties of the microvine, main results from various research programs performed with the microvine model will be presented

A new class of cleavable fluorescent nucleotides: synthesis and optimization as reversible terminators for DNA sequencing by synthesis

Fluorescent 2′-deoxynucleotides containing a protecting group at the 3′-O-position are reversible terminators enabling array-based DNA sequencing by synthesis (SBS) approaches. Herein, we describe the synthesis of a new family of 3′-OH unprotected cleavable fluorescent 2′-deoxynucleotides and their evaluation as reversible terminators for high-throughput DNA SBS strategies. In this first version, all four modified nucleotides bearing a cleavable disulfide Alexa Fluor® 594 dye were assayed for their ability to act as a reversible stop for the incorporation of the next labeled base. Their use in SBS leaded to a signal-no signal output after successive addition of each labeled nucleotide during the sequencing process (binary read-out). Solid-phase immobilized synthetic DNA target sequences were used to optimize the method that has been applied to DNA polymerized colonies or clusters obtained by in situ solid-phase amplification of fragments of genomic DNA template

BTA, a novel reagent for DNA attachment on glass and efficient generation of solid-phase amplified DNA colonies

The tricarboxylate reagent benzene-1,3,5-triacetic acid (BTA) was used to attach 5′-aminated DNA primers and templates on an aminosilanized glass surface for subsequent generation of DNA colonies by in situ solid-phase amplification. We have characterized the derivatized surfaces for the chemical attachment of oligonucleotides and evaluate the properties relevant for the amplification process: surface density, thermal stability towards thermocycling, functionalization reproducibility and storage stability. The derivatization process, first developed for glass slides, was then adapted to microfabricated glass channels containing integrated fluidic connections. This implementation resulted in an important reduction of reaction times, consumption of reagents and process automation. Innovative analytical methods for the characterization of attached DNA were developed for assessing the surface immobilized DNA content after amplification. The results obtained showed that the BTA chemistry is compatible and suitable for forming highly dense arrays of DNA colonies with optimal surface coverage of about 10 million colonies/cm2 from the amplification of initial single-template DNA molecules immobilized. We also demonstrate that the dsDNA colonies generated can be quantitatively processed in situ by restriction enzymes digestion. DNA colonies generated using the BTA reagent can be used for further sequence analysis in an unprecedented parallel fashion for low-cost genomic studie

The Comparability of Men Who Have Sex With Men Recruited From Venue-Time-Space Sampling and Facebook: A Cohort Study

Background: Recruiting valid samples of men who have sex with men (MSM) is a key component of the US human immunodeficiency virus (HIV) surveillance and of research studies seeking to improve HIV prevention for MSM. Social media, such as Facebook, may present an opportunity to reach broad samples of MSM, but the extent to which those samples are comparable with men recruited from venue-based, time-space sampling (VBTS) is unknown. Objective: The objective of this study was to assess the comparability of MSM recruited via VBTS and Facebook. Methods: HIV-negative and HIV-positive black and white MSM were recruited from June 2010 to December 2012 using VBTS and Facebook in Atlanta, GA. We compared the self-reported venue attendance, demographic characteristics, sexual and risk behaviors, history of HIV-testing, and HIV and sexually transmitted infection (STI) prevalence between Facebook- and VTBS-recruited MSM overall and by race. Multivariate logistic and negative binomial models estimated age/race adjusted ratios. The Kaplan-Meier method was used to assess 24-month retention. Results: We recruited 803 MSM, of whom 110 (34/110, 30.9% black MSM, 76/110, 69.1% white MSM) were recruited via Facebook and 693 (420/693, 60.6% black MSM, 273/693, 39.4% white MSM) were recruited through VTBS. Facebook recruits had high rates of venue attendance in the previous month (26/34, 77% among black and 71/76, 93% among white MSM; between-race P=.01). MSM recruited on Facebook were generally older, with significant age differences among black MSM (P=.02), but not white MSM (P=.14). … See full text for complete abstract

Berry development of grapevines: Relations between the growth of berries and their DNA content indicate cell multiplication and enlargement

DNA of berries (cv. Shiraz) was extracted and quantified to determine, indirectly, the rate of cell division and enlargement in the grape pericarp. The increase of total DNA in the pericarp begins at anthesis in the ovary of grapevine flowers (day 0, 100 % of flowers at full bloom). This increase in DNA continues during the herbaceous growth period until 35 d after anthesis (day 35, 19 d before the onset of veraison). Total DNA per berry pericarp does not increase linearly during this growth period since 75 % of the DNA has already accumulated before day 20. We determined a cell enlargement index (CEI), to estimate the mean cellular volume. The pericarp cell size increases 16-fold during the whole growth of berries. Volume increase is nearly linear from berry set to the beginning of veraison and thereafter until maturity. The importance of determination of cell division and enlargement of berry pericarp based on the DNA content and its possible application in studies on the influence of environmental factors on berry growth is discussed

BTA, a novel reagent for DNA attachment on glass and efficient generation of solid-phase amplified DNA colonies

The tricarboxylate reagent benzene-1,3,5-triacetic acid (BTA) was used to attach 5′-aminated DNA primers and templates on an aminosilanized glass surface for subsequent generation of DNA colonies by in situ solid-phase amplification. We have characterized the derivatized surfaces for the chemical attachment of oligonucleotides and evaluate the properties relevant for the amplification process: surface density, thermal stability towards thermocycling, functionalization reproducibility and storage stability. The derivatization process, first developed for glass slides, was then adapted to microfabricated glass channels containing integrated fluidic connections. This implementation resulted in an important reduction of reaction times, consumption of reagents and process automation. Innovative analytical methods for the characterization of attached DNA were developed for assessing the surface immobilized DNA content after amplification. The results obtained showed that the BTA chemistry is compatible and suitable for forming highly dense arrays of DNA colonies with optimal surface coverage of about 10 million colonies/cm(2) from the amplification of initial single-template DNA molecules immobilized. We also demonstrate that the dsDNA colonies generated can be quantitatively processed in situ by restriction enzymes digestion. DNA colonies generated using the BTA reagent can be used for further sequence analysis in an unprecedented parallel fashion for low-cost genomic studies