FELINE ATRIAL NATRIURETIC PEPTIDE (ANP) HAS A SINGLE COPY GENE

O peptídeo natriurético atrial felino (PNA) é um hormônio sintetizado pelo miocárdio cardíaco atrial que, uma vez liberado na circulação, produz diurese, natriurese e vasodilatação periférica. Nós recentemente isolamos, sequenciamos e estabelemos a expressão cardíaca normal do PNA felino. No presente estudo, nós apresentamos o número de cópias gênicas do PNA em gatos. Foram extraídas amostras de DNA genômico do sangue periférico humano e felino, as quais foram purificadas e digeridas com as enzimas de restrição EcoRI, BamHI e HindIII, com posterior realização da técnica de Southern Blots. Primers para PCR, confeccionados para regiões de alta conservatividade entre espécies, foram utilizados para amplificação, clonagem e sequenciamento de um produto de 900 pares de bases, posteriormente utilizado como sonda de DNA. O gene do PNA felino possui uma única cópia gênica, a exemplo do PNA humano. Devido a sua similaridade, sondas de DNA felino puderam ser utilizadas para a hibridização de DNA genômico tanto do gato como do homem. Abstract Atrial natriuretic peptide (ANP) is a hormone normally synthesized by the cardiac atrial myocardium that once released, produces diuresis, natriuresis and peripheral vasodilation. We have recently isolated, sequenced and assessed the normal cardiac expression of feline ANP. In this study, we report on the number of copies of the feline ANP gene, which could have an effect on future molecular biology studies of ANP gene expression in cat models of cardiovascular disease. Cat and human genomic DNA (gDNA) were extracted for Southern blotting from blood. The purified DNA was digested with the restriction enzymes EcoRI, BamHI and HindIII followed by agarose gel electrophoresis and blotting onto nytran membranes. A feline ANP cDNA probe of approximately 900 base pairs was used for hybridization of the membranes. The results of Southern blotting showed that both the feline and human genomes contain a single copy of the ANP gene

Gene expression during preimplantation mouse development

To develop a resource for the identification and isolation of genes expressed in the early mammalian embryo, large and representative cDNA libraries were constructed from unfertilized eggs, and two-cell, eight-cell, and blastocyst-stage mouse embryos. Using these libraries, we now report the first stages at which the cytokines interleukin (IL)-6, IL-1 beta, and interferon (IFN)-gamma are transcribed in the developing embryo and the presence of IL-7 transcripts in the unfertilized egg. Transcripts for IL-1 alpha, -2, -3, -4, or -5 were not detected at these stages. To identify novel genes expressed on activation of the embryonic genome, the egg and eight-cell stage-specific cDNA libraries were subtracted from the two-cell library, yielding a specialized cDNA library enriched for transcripts expressed at the two-cell stage. Sequence and Southern blot analysis of several of these cDNAs expressed predominantly at the two-cell stage of embryogenesis revealed them to be from novel genes, thereby providing the first molecular tools with which to approach the study of gene expression in the early mammalian embryo

Thermal diffusivity measurements of metastable austenite during continuous cooling

The thermal diffusivity of the metastable undercooled austenite is relevant for the quantitative analysis of the carbon and low-alloy steel quench. The standard laser-flash method requires prior thermal equilibrium between the sample and the furnace, which may not be possible to achieve without allowing the metastable phase to transform. Nevertheless, depending upon the steel's hardenability, the thermal transient due to a laser pulse may be much shorter than a cooling transient sufficiently steep to prevent the transformation of the austenite. In one such case, flash measurements were performed during continuous sample cooling and the thermal diffusivity of the metastable austenite was determined by using an extension of the standard analytical model. The adopted analytical model and data reduction procedure are described and the limitations and uncertainties of this method are discussed, also with the aid of a non-linear numerical simulation. The measured thermal diffusivity of the under cooled low-alloy austenite decreases linearly from 5.4•10−6 m2 s−1 at 1133 K to 4.3•10−6 m2 s−1 at 755 K; this trend is in broad agreement with one previous set of measurements upon a low-alloy undercooled austenite and with a large number of previous standard measurements upon stable (high-alloy) austenitic stainless steels