RESUMEN
We have generated an improved assembly and gene annotation of the pig X Chromosome, and a first draft assembly of the pig Y Chromosome, by sequencing BAC and fosmid clones from Duroc animals and incorporating information from optical mapping and fiber-FISH. The X Chromosome carries 1033 annotated genes, 690 of which are protein coding. Gene order closely matches that found in primates (including humans) and carnivores (including cats and dogs), which is inferred to be ancestral. Nevertheless, several protein-coding genes present on the human X Chromosome were absent from the pig, and 38 pig-specific X-chromosomal genes were annotated, 22 of which were olfactory receptors. The pig Y-specific Chromosome sequence generated here comprises 30 megabases (Mb). A 15-Mb subset of this sequence was assembled, revealing two clusters of male-specific low copy number genes, separated by an ampliconic region including the HSFY gene family, which together make up most of the short arm. Both clusters contain palindromes with high sequence identity, presumably maintained by gene conversion. Many of the ancestral X-related genes previously reported in at least one mammalian Y Chromosome are represented either as active genes or partial sequences. This sequencing project has allowed us to identify genes--both single copy and amplified--on the pig Y Chromosome, to compare the pig X and Y Chromosomes for homologous sequences, and thereby to reveal mechanisms underlying pig X and Y Chromosome evolution.
Asunto(s)
Cromosomas de los Mamíferos/genética , Evolución Molecular , Porcinos/genética , Cromosoma X/genética , Cromosoma Y/genética , Animales , Secuencia de Bases , Gatos/genética , Perros/genética , Femenino , Conversión Génica , Expresión Génica , Biblioteca de Genes , Orden Génico , Humanos , Masculino , Datos de Secuencia Molecular , Alineación de Secuencia , Análisis de Secuencia de ADNRESUMEN
Electrophysiological properties and molecular background of the zebrafish (Danio rerio) cardiac inward rectifier current (IK1) were examined. Ventricular myocytes of zebrafish have a robust (-6.7 ± 1.2 pA pF(-1) at -120 mV) strongly rectifying and Ba(2+)-sensitive (IC50 = 3.8 µM) IK1. Transcripts of six Kir2 channels (drKir2.1a, drKir2.1b, drKir2.2a, drKir2.2b, drKir2.3, and drKir2.4) were expressed in the zebrafish heart. drKir2.4 and drKir2.2a were the dominant isoforms in both the ventricle (92.9 ± 1.5 and 6.3 ± 1.5%) and the atrium (28.9 ± 2.9 and 64.7 ± 3.0%). The remaining four channels comprised together less than 1 and 7 % of the total transcripts in ventricle and atrium, respectively. The four main gene products (drKir2.1a, drKir2.2a, drKir2.2b, drKir2.4) were cloned, sequenced, and expressed in HEK cells for electrophysiological characterization. drKir2.1a was the most weakly rectifying (passed more outward current) and drKir2.2b the most strongly rectifying (passed less outward current) channel, whilst drKir2.2a and drKir2.4 were intermediate between the two. In regard to sensitivity to Ba(2+) block, drKir2.4 was the most sensitive (IC50 = 1.8 µM) and drKir2.1a the least sensitive channel (IC50 = 132 µM). These findings indicate that the Kir2 isoform composition of the zebrafish heart markedly differs from that of mammalian hearts. Furthermore orthologous Kir2 channels (Kir2.1 and Kir2.4) of zebrafish and mammals show striking differences in Ba(2+)-sensitivity. Structural and functional differences needs to be taken into account when zebrafish is used as a model for human cardiac electrophysiology, cardiac diseases, and in screening cardioactive substances.
Asunto(s)
Potenciales de Acción , Miocitos Cardíacos/metabolismo , Canales de Potasio de Rectificación Interna/metabolismo , Multimerización de Proteína , Proteínas de Pez Cebra/metabolismo , Secuencia de Aminoácidos , Animales , Bario/farmacología , Células Cultivadas , Células HEK293 , Atrios Cardíacos/citología , Ventrículos Cardíacos/citología , Humanos , Datos de Secuencia Molecular , Miocitos Cardíacos/fisiología , Bloqueadores de los Canales de Potasio/farmacología , Canales de Potasio de Rectificación Interna/química , Canales de Potasio de Rectificación Interna/genética , Subunidades de Proteína/química , Subunidades de Proteína/genética , Subunidades de Proteína/metabolismo , Pez Cebra , Proteínas de Pez Cebra/química , Proteínas de Pez Cebra/genéticaRESUMEN
Efforts to adapt and extend graphic arts printing techniques for demanding device applications in electronics, biotechnology and microelectromechanical systems have grown rapidly in recent years. Here, we describe the use of electrohydrodynamically induced fluid flows through fine microcapillary nozzles for jet printing of patterns and functional devices with submicrometre resolution. Key aspects of the physics of this approach, which has some features in common with related but comparatively low-resolution techniques for graphic arts, are revealed through direct high-speed imaging of the droplet formation processes. Printing of complex patterns of inks, ranging from insulating and conducting polymers, to solution suspensions of silicon nanoparticles and rods, to single-walled carbon nanotubes, using integrated computer-controlled printer systems illustrates some of the capabilities. High-resolution printed metal interconnects, electrodes and probing pads for representative circuit patterns and functional transistors with critical dimensions as small as 1 mum demonstrate potential applications in printed electronics.