Asunto(s)
Adenocarcinoma/genética , Empalme Alternativo , Colágeno Tipo X/genética , Mucosa Esofágica/patología , Neoplasias Esofágicas/genética , Adenocarcinoma/patología , Adulto , Anciano , Anciano de 80 o más Años , Biopsia , Carcinogénesis/genética , Movimiento Celular/genética , Conjuntos de Datos como Asunto , Neoplasias Esofágicas/patología , Femenino , Técnicas de Silenciamiento del Gen , Células HEK293 , Humanos , Masculino , Persona de Mediana Edad , Isoformas de Proteínas/genética , RNA-SeqRESUMEN
Analysis of environmental DNA (eDNA) enables the detection of species of interest from water and soil samples, typically using species-specific PCR. Here, we describe a method to characterize the biodiversity of a given environment by amplifying eDNA using primer pairs targeting a wide range of taxa and high-throughput sequencing for species identification. We tested this approach on 91 water samples of 40 mL collected along the Cuyahoga River (Ohio, USA). We amplified eDNA using 12 primer pairs targeting mammals, fish, amphibians, birds, bryophytes, arthropods, copepods, plants and several microorganism taxa and sequenced all PCR products simultaneously by high-throughput sequencing. Overall, we identified DNA sequences from 15 species of fish, 17 species of mammals, 8 species of birds, 15 species of arthropods, one turtle and one salamander. Interestingly, in addition to aquatic and semi-aquatic animals, we identified DNA from terrestrial species that live near the Cuyahoga River. We also identified DNA from one Asian carp species invasive to the Great Lakes but that had not been previously reported in the Cuyahoga River. Our study shows that analysis of eDNA extracted from small water samples using wide-range PCR amplification combined with high-throughput sequencing can provide a broad perspective on biological diversity.
Asunto(s)
Biodiversidad , Clasificación , ADN/genética , Metagenómica , Anfibios/clasificación , Anfibios/genética , Animales , Aves/clasificación , Aves/genética , Carpas/clasificación , Carpas/genética , Simulación por Computador , ADN/aislamiento & purificación , Ecosistema , Monitoreo del Ambiente , Secuenciación de Nucleótidos de Alto Rendimiento , Mamíferos/clasificación , Mamíferos/genética , Plantas/clasificación , Ríos , Especificidad de la EspecieRESUMEN
We present a modulation transfer function (MTF) calibration method based on binary pseudo-random (BPR) one-dimensional sequences and two-dimensional arrays as an effective method for spectral characterization in the spatial frequency domain of a broad variety of metrology instrumentation, including interferometric microscopes, scatterometers, phase shifting Fizeau interferometers, scanning and transmission electron microscopes, and at this time, x-ray microscopes. The inherent power spectral density of BPR gratings and arrays, which has a deterministic white-noise-like character, allows a direct determination of the MTF with a uniform sensitivity over the entire spatial frequency range and field of view of an instrument. We demonstrate the MTF calibration and resolution characterization over the full field of a transmission soft x-ray microscope using a BPR multilayer (ML) test sample with 2.8 nm fundamental layer thickness. We show that beyond providing a direct measurement of the microscope's MTF, tests with the BPRML sample can be used to fine tune the instrument's focal distance. Our results confirm the universality of the method that makes it applicable to a large variety of metrology instrumentation with spatial wavelength bandwidths from a few nanometers to hundreds of millimeters.
RESUMEN
We combined immunostaining and fluorescence in situ hybridization (FISH) methodology to directly examine meiotic exchanges in over 2,000 pachytene stage spermatocytes from 25 individuals. Our results indicate that, on average, there are about 50 exchanges per cell and that, with the exception of the acrocentric chromosomes, all chromosome arms harbor at least one exchange. We also identified significant among-individual variation in the mean number of exchanges, with an approximate 20% difference between individuals with "low" and those with "high" exchange frequencies.
Asunto(s)
Meiosis/genética , Recombinación Genética/genética , Proteínas Adaptadoras Transductoras de Señales , Adulto , Anciano , Anciano de 80 o más Años , Envejecimiento/genética , Proteínas Portadoras , Cromosomas Humanos/genética , Cromosomas Humanos/metabolismo , Intercambio Genético/genética , Variación Genética/genética , Humanos , Hibridación Fluorescente in Situ , Masculino , Persona de Mediana Edad , Homólogo 1 de la Proteína MutL , Proteínas de Neoplasias/metabolismo , Proteínas Nucleares , Complejo Sinaptonémico/metabolismoRESUMEN
Attempts to identify genetic contributors to human meiotic nondisjunction have met with little, if any, success. Thus, recent reports linking Down syndrome to maternal polymorphisms at either of two folate metabolism enzymes, methylenetetrahydrofolate reductase (MTHFR) and methionine synthase reductase (MTRR), have generated considerable interest. In the present report, we asked whether variation at MTHFR (677C-->T) or MTRR (66A-->G) might be associated with human trisomies other than trisomy 21. We analyzed maternal polymorphisms at MTHFR and MTRR in 93 cases of sex-chromosome trisomy, 44 cases of trisomy 18, and 158 cases of autosomal trisomies 2, 7, 10, 13, 14, 15, 16, 18, or 22, and compared the distributions of genotypes to those of control populations. We observed a significant increase in the MTHFR polymorphism in mothers of trisomy 18 conceptuses but were unable to identify any other significant associations. Overall, our observations suggest that, at least for the sex chromosomes and for a combined set of autosomal trisomies, polymorphisms in the folate pathway are not a significant contributor to human meiotic nondisjunction.