Daily changes of GABA and taurine concentrations in various hypothalamic areas are affected by chronic hyperprolactinemia

This study was designed to characterize, in anterior, mediobasal, and posterior hypothalamic and median eminence, the 24h changes of gamma aminobutyric acid (GABA) and taurine (TAU) contents in adult male rats and to analyze whether chronic hyperprolactinemia may affect these patterns. Rats were turned hyperprolactinemic by a pituitary graft. Plasma prolactin (PRL) levels increased after pituitary grafting at all time points examined. A disruption of the circadian rhythm was observed in pituitary-grafted rats, whereas GABA and TAU content followed daily rhythms in all areas studied in controls. In the mediobasal hypothalamus, two peaks for each amino acid were found at midnight and midday. In the anterior hypothalamus, GABA and TAU showed only one peak of concentration at midnight. In the posterior hypothalamus, the values of both GABA and TAU were higher during the light as compared to the dark phase of the photoperiod. In the median eminence GABA content peaked at 20:00h, the time when TAU exhibited the lowest values. Hyperprolactinemia abolished the 24h changes of GABA in the mediobasal hypothalamus and reduced its content as compared to controls. Hyperprolactinemia advanced the diurnal peak of TAU to 12:00h in the mediobasal hypothalamus and did not modify the 24:00h peak. In the anterior hypothalamus, hyperprolactinemia increased GABA and TAU contents during the light phase while it decreased them during the dark phase of the photoperiod. In the posterior hypothalamus hyperprolactinemia did not modify GABA or TAU patterns as compared to controls. In the median eminence hyperprolactinemia increased the 20:00h peak of GABA and shift advanced the decrease in TAU content at 20:00h and its maximum at 24:00h as compared to controls. These data show that GABA and TAU content exhibit specific daily patterns in each hypothalamic region studied. PRL differentially affects the daily pattern of these amino acids in each hypothalamic region analyzed.     

Neo-clerodane diterpenoids from Croton schiedeanus

Two new neo-clerodane type furano diterpenoids were isolated from the aerial part of Croton schiedeanus, besides the clerodane diterpenes cis- and trans-dehydrocrotonin, previously isolated from other species of Croton. Structural elucidation was achieved on basis of extensive NMR experiments, including X-ray diffraction analysis and molecular mechanics calculations. The previously known flavonoids ayanin and quercetin-3,7-dimethyl ether were also obtained from the extract of this plant.     

Microspore-derived embryos from Quercus suber anthers mimic zygotic embryos and maintain haploidy in long-term anther culture

Microspore-derived embryos produced from cork oak anther cultures after long-term incubations (up to 10-12 months) were analysed in order to determine the genetic variability and ploidy level stability, as well as morphology, developmental pattern and cellular organisation. Most of the embryos from long-term anther cultures were haploid (90.7%), corresponding to their microspore origin. The presence of a low percentage of diploid embryos (7.4%) was observed. Microsatellite analysis of haploid embryos, indicated different microspores origins of the same anther. In the diploid embryos, homozygosity for different alleles was detected from anther wall tissues, excluding the possibility of clonal origin. The maintenance of a high proportion of haploid embryos, in long-term anther cultures, is similar in percentage to that reported in embryos originating after 20 days of plating (Bueno et al. 1997). This suggests that no significant alterations in the ploidy level occurred during long incubations (up to 12 months). These results suggest that ploidy changes are rare in this in vitro system, and do not significantly increase during long-term cultures. Microscopical studies of the microspore embryos in various stages revealed a healthy and well developed anatomy with no aberrant or chimeric structures. The general morphology of embryos appearing at different times after plating, looked similar to that of earlier embryos, as well as the zygotic embryos, indicating that they represent high quality material for cork oak breeding.     

APRT from erythrocytes of HGPRT deficient patients: Kinetic,regulatory and thermostability properties

Adenine phosphoribosyltransferase (APRT) has been 1200-fold purified from erythrocytes of a patient with partial hipoxanthine-guanine phosphoribosyltransferase (HGPRT) deficiency, Propositus, and in those of a control^HPRT+, with 20% efficiency in both proteins and specific activity of 550 and 243 nmol/h/mgprotein. The specific activity determined in the Propositus enzyme was, in all purification steps, higher than that of the control^HPRT+. Significant changes were found in their thermal stabilities. Half inactivation times at each temperature studied are greater for the Propositus enzyme in the temperature interval 60–80°C. No significant difference has been observed in the affinity constants for adenine and PRPP substrates. Studies on inhibition by the reaction product suggest that AMP is a competitive inhibitor with respect to PRPP in both enzymes, with K_i values of 150 M in Propositus and 220 M in control^HPRT+.     

Rga5p is a specific Rho1p GTPase-activating protein that regulates cell integrity in Schizosaccharomyces pombe

Schizosaccharomyces pombe Rho1p regulates (1,3)beta-d-glucan synthesis and is required for cell integrity maintenance and actin cytoskeleton organization, but nothing is known about the regulation of this protein. At least nine different S. pombe genes code for proteins predicted to act as Rho GTPase-activating proteins (GAPs). The results shown in this paper demonstrate that the protein encoded by the gene named rga5+ is a GAP specific for Rho1p. rga5+ overexpression is lethal and causes morphological alterations similar to those reported for Rho1p inactivation. rga5+ deletion is not lethal and causes a mild general increase in cell wall biosynthesis and morphological alterations when cells are grown at 37 degrees C. Upon mild overexpression, Rga5p localizes to growth areas and possesses both in vivo and in vitro GAP activity specific for Rho1p. Overexpression of rho1+ in rga5Delta cells is lethal, with a morphological phenotype resembling that of the overexpression of the constitutively active allele rho1G15V. In addition (1,3)beta-d-glucan synthase activity, regulated by Rho1p, is increased in rga5Delta cells and decreased in rga5-overexpressing cells. Moreover, the increase in (1,3)beta-d-glucan synthase activity caused by rho1+ overexpression is considerably higher in rga5Delta than in wild-type cells. Genetic interactions suggest that Rga5p is also important for the regulation of the other known Rho1p effectors, Pck1p and Pck2p.     

Phylogenetic reconstruction of the genusBrachypodium P. Beauv. (Poaceae) from combined sequences of chloroplastndhF gene and nuclear ITS

A phylogenetic reconstruction of eight species of the genusBrachypodium P. Beauv. (Poaceae) has been obtained combining sequence data from the chloroplastndhF gene and the nuclear ITS, and using five representatives of tribes Triticeae (Secale), Poeae (Lolium), Meliceae (Melica, Glyceria) and Oryzeae (Oryza) as out-groups. Similar numbers of informative substitutions for the ingroup species were provided by both the 3 region of the chloroplastndhF gene and the nuclear ITS region. The Mediterranean annualBrachypodium distachyon appears to be the basal lineage, followed by the divergence of the New World non-rhizomatousB. mexicanum, which antedates the separation of a core of six European and Eurosiberian rhizomatous perennials (Brachypodium arbuscula, B. retusum, B. rupestre, B. phoenicoides, B. pinnatum, andB. sylvaticum). The evolutionary reconstruction based on sequences of the chloroplast and the nuclear genomes is congruent with topologies obtained from analysis of RAPD data.