Archivos de biologia y medicina experimentales最新文献

Administration of estradiol (E2) as a single subcutaneous injection, but not as a short intravenous infusion (less than 150 min), accelerates oviductal embryo transport in pregnant rats although the first mode determines lower E2 circulating levels. Since progesterone (P) can antagonize the effect of E2 on embryo transport we examined the circulating P levels under these two modes of E2 administration. Rats were treated on day 1 of pregnancy with 5 micrograms E2 given s.c. or i.v. (10 min infusion). Other groups were either hypophysectomized (HPX), adrenalectomized (ADX) or ovariectomized (OVX) prior to E2 treatment to prevent P rise, or were treated with E2 plus RU486 to block the action of P. Some groups were autopsied at short intervals following treatment to measure P levels and others 24 h later to assess the effect of treatments on embryo transport. P was increased several fold by i.v. infusions of E2 or vehicle alone in intact and OVX rats but not in HPX or ADX rats, whereas s.c. administration of E2 did not change P levels unless it was given concomitantly with i.v. infusion of vehicle. The short i.v. infusion of E2 accelerated embryo transport in HPX, ADX, or RU486 treated rats but not in intact rats. The s.c. injection of E2 accelerated embryo transport even when it was accompanied by an i.v. infusion of vehicle. The data does not exclude the participation of glucocorticoids in the above phenomena but agrees with the view that it is the transient increase in adrenal P secretion which blunts the oviductal response to a brief pulse of E2.

Cystic Fibrosis (CF) is the most common lethal genetic autosomic disease in Caucasians. The disease expresses itself in airway and other epithelial cells as a defective chloride ion absorption and secretion. At least, an abnormal cAMP-dependent regulation of an apically located chloride channel has been proposed as the underlying molecular defect. The gene responsible for CF has been identified and predicted to encode a membrane protein termed cystic fibrosis transmembrane conductance regulator (CFTR). The functional role of the predicted protein remains unclear, although strong evidence suggest that it is directly or indirectly involved in regulation of the apical chloride permeability in epithelial cells. This review discusses the fundamental issues currently being investigated in CF.

The chemolithotrophic acidophilic bacteria, Thiobacillus ferrooxidans is considered as the most important microorganism in relation to copper and uranium bioleaching ability. Since T. ferrooxidans is a strict chemolithotrophic microorganism, its genetic manipulation is a very hard task. Until now, all efforts have been unsuccessful. Therefore, we decided to approach the problem in steps, trying initially to manipulate some T. ferrooxidans related strains. We chose Thiobacillus acidophilus that shares its habitat with T. ferrooxidans and Thiobacillus intermedius, for its heterotrophic nature that makes them easier to grow and suitable for heterologous conjugation. The main objective of this work was directed towards the isolation and characterization of transcription promoters from T. acidophilus and T. ferrooxidans genomic DNA. Four different promoters from T. acidophilus and four from T. ferrooxidans were isolated and sequenced. In order to test their functional capacity in bacterial systems different from E. coli, they were subcloned and transferred to other bacteria. One of these recombinant plasmids was successfully transferred to T. intermedius and from it to Ps. putida. The subcloned promoter was able to confer streptomycin resistance to Ps. putida.

The expanding study of biological rhythms requires the use of refined methods of time series analysis. We propose the use of ARIMA (Autoregressive Integrated Moving Averages) model, a powerful statistical tool of relatively recent development. A group of 5 patients with Affective Disorders (2 bipolars, 3 unipolars) and 1 patient with Adjustment Disorder self-assessed their AS every 8 hours for about a month. The affective state (AS) was estimated for 4 indicators: the two main constructs (Mood and Drive) of the segmented Visual Scale ESTA III and two bipolar items (Anxiety and Drowsiness). Mood and Drive are continuous variables, while Anxiety and Drowsiness are ordinal ones. Strictly speaking, ARIMA modelling is not valid with ordinal data. However, comparison of models of the two kinds of variables reveals no significant differences. This points out to a certain robustness of the method. Most of the series were non-stationary but could be transformed taking no more than two differences. The models made a very good fit of the data. Statistically significant coefficients on different lags may indicate the presence of circadian and infradian periodicities in the series. Further applications of ARIMA models to biological and psychological rhythmometry may be quite useful.

Plant cells by means of their totipotency and aided by in vitro culture techniques can be induced to perform morphogenesis leading to somatic embryoids and massive clonal multiplication; microspores or pollen can be triggered to recover haploid plants, then characters expressed via haploidy can be selected and fixed. Protoplasts from different species can lead to recombinations. We report here work done on Carica pubescens, where somatic embryoids were obtained from cells; in Prunus avium androgenesis leading to pollen calli was triggered, while plants were recovered from Nicotiana tabacum anthers. Fusion products were obtained using C. pubescens and C. papaya protoplasts, leading up to calli and shoots.