Plant O-methyltransferases: molecular analysis,common signature and classification

Comparative analysis of the predicted amino acid sequences of a number of plant O-methyltransferase cDNA clones show that they share some 32–71% sequence identity, and can be grouped according to the different compounds they utilise as substrates. Five highly conserved regions are proposed as a signature for plant O-methyltransferases, two of which (regions I and IV) are believed to be involved in S-adenosyl-L-methionine and metal binding, respectively. The glycine-rich signature regions include a 36 amino acid domain which is located in the mid-terminal section of the carboxy terminus of most O-methyltransferase sequences. Cladistic analysis of the amino acid sequences suggests that plant O-methyltransferases may have arisen from common ancestral genes that were driven by different structural and/or functional requirements, and whose descendants segregated into different biochemical species. A comprehensive classification of plant O-methyltransferases is proposed following the guidelines of the Commission of Plant Gene Nomenclature.     

Effects of human fetal gastroenteric mesenchymal cells on some developmental aspects of animal gut endoderm

Human intestinal and gastric mesenchymal cells were associated with chick and rat intestinal endoderm in order to test their species-specific capacity on epithelial differentiation. Primary cell cultures were established from human intestinal and gastric mesenchyme. Animal intestinal endoderms were associated with both cell types, grafted in ovo and allowed to develop for 12 days. The morphologic and enzymatic differentiation of the recombinants demonstrated two types of inductive properties exerted by human fetal intestinal and gastric mesenchymal cells, respectively. Firstly, human intestinal mesenchymal cells triggered intrinsic developmental capacities in chick and rat endoderm, i.e. enhanced structural brush-border maturation in both species and precocious sucrase induction in rat endoderm. Secondly, human gastric mesenchymal cells provoked the partial conversion of chick intestinal endoderm into gastric structures. Such properties were not found in homologous animal mesenchymes.     

Physical mapping of the BglI,BglII, PstI and EcoRI restriction fragments of staphylococcal phage ϕ11 DNA

Molecular Genetics and Genomics - A cleavage map of the generalized transducing staphylococcal phage ϕ11 DNA has been constructed by reciprocal double digestion. All three BglI, the six BglII,...     

Immunocytochemical study of the GABAergic innervation of the mouse pituitary by use of antibodies against gamma-aminobutyric acid (GABA)

Summary The GABAergic innervation of the mouse pituitary, including the median eminence, was studied at light microscopic and ultrastructural levels by use of a pre-embedding immunocytochemical technique with antibodies directed against GABA. In the median eminence, a high density of GABA-immunoreactive fibers was found in the external layer where the GABAergic varicosities were frequently observed surrounding the blood vessels of the primary capillary plexus. In the internal and subependymal layers, only few fibers were immunoreactive. The intense labeling of the external layer was observed in the entire rostro-caudal extent of the median eminence. In the pituitary proper, a dense network of GABA-immunoreactive fibers was revealed throughout the neural and intermediate lobes, entering via the hypophyseal stalk. The anterior and tuberal lobes were devoid of any immunoreactivity. The GABA-immunoreactive terminals were characterized in the median eminence, and in the intermediate and posterior lobes at the electron-microscopic level. They contained small clear vesicles, occasionally associated with dense-core vesicles or neurosecretory granules. In the intermediate lobe they were seen to be in contact with the glandular cells. In the posterior lobe and in the median eminence, GABA-immunoreactive terminals were frequently located in the vicinity of blood vessels. These results further support the concept of a role of GABA in the regulation of hypophyseal functions, via the portal blood for the anterior lobe, directly on the cells in the intermediate lobe, and via axo-axonic mechanisms in the median eminence and posterior lobe.     

Regulation of hepatic phosphoenolpyruvate carboxykinase (GTP) Role of dietary proteins and amino acids in vivo and in the isolated perfused rat liver

The effect of protein feeding and the addition of amino acids on the activity of hepatic phosphoenolpyruvate carboxykinase (GTP: oxalacetate carboxylyase (transphosphorylating), EC 4.1.1.32) was investigated in vivo and in the isolated perfused rat liver. Protein feeding resulted in a considerable increase in phosphoenolpyruvate carboxykinase activity within 6 h. This rise was independent of the presence of glucocorticoids.In the isolated perfused liver system amino acids per se had a small effect on phosphoenolpyruvate carboxykinase activity and led to an increase by 20% when glucocorticoids were present, but resulted in a rise by 100% when glucocorticoids plus dibutyryl cyclic AMP were added to the perfusion medium. The effect of amino acids in the presence of dibutyryl cyclic AMP could also be observed in the liver of glucocorticoid-deprived rats.Cycloheximide, a translational inhibitor, totally blocked all effects of amino acids on enzyme activity.These results indicate that the concentration of amino acids in the portal vein modify the regulation of phosphoenolpyruvate carboxykinase by cyclic AMP.