Anatomical studies of branchlet abscission related to crown modification in Quercus cerris L.

The basic anatomy of lateral twig insertion onto the main branch in both healthy and damaged Quercus cerris L. trees was studied. An abscission zone is always present: in healthy trees it is formed by a smaller number of cell layers than in damaged ones, where it is more evident with many layers of cells. Cells of the abscission zone are roundish, with many intercellular spaces between them; cell walls are thin, non-lignified and without secondary walls. No starch was found in cells of the abscission zone, where, instead, a few scattered calcium oxalate druses are seen.     

Corticotropin releasing factor decidualizes human endometrial stromal cells in vitro. Interaction with progestin

Decidualization of endometrial cells is a hormone-dependent process of differentiation which occurs during the menstrual cycle and pregnancy. Recent in vitro studies have revealed that cAMP and its generators induce decidualization of stromal cells isolated from proliferative endometrium and that progestins enhance the effect of cAMP. Since corticotropin releasing factor (CRF) generates cAMP and prostaglandins in other organs, in the present study the effect of CRF, a hypothalamic factor also produced by decidua and fetal membranes, on in vitro decidualization of endometrial stromal cells was evaluated. The addition of CRF to a culture medium of stromal cells induced in vitro decidualization, as indicated by morphologic changes from elongated fibroblast-like cells into larger and round cells and by the release of prolactin in the medium. The effect of CRF on stromal cells and on prolactin release was significantly augmented by the coincubation in the presence of medroxyprogesterone acetate. This observation indicates CRF as a novel factor of decidualization and confirms that progestins act as enhancers of the expression of decidual products.     

Displacement of O2 and CO by cyanide from the active site of helix pomatia β-hemocyanin.: Formation of a mixed-liganded species

Addition of KCN to Helix pomatia β-hemocyanin fully saturated with either O₂ or CO results in a decrease of the spectroscopic properties of the protein (absorbance at 340 nm and luminescence at 550 nm) due to the displacement of the gaseous ligands (O₂ or CO) from the active site. The anionic form of cyanide (CN^?) is supposed to bind to the active site; its intrinsic affinity for the protein, as calculated from independent O₂ and CO displacement experiments, is between 2 and 6 × 10⁶M^?1. The replacement of O₂ or CO shows some differences which may be correlated with the different modes of binding at the active site. Thus, while displacement of oxygen by cyanide is hyperbolic, addition of cyanide to carbonylated hemocyanin shows a lag phase. This finding suggests the formation of a mixed liganded complex at the active site. The simultaneous presence of CO and CN^? at the active site of hemocyanin is also supported by the experiment in which addition of small amounts of KCN to hemocyanin partially saturated with O₂ and CO gives rise to an increase of emission intensity and a concomitant decrease of the O₂ absorption band. The mixed-liganded species displays luminescence properties similar to those of CO-saturated hemocyanin, and the formation of the complex is reversible on dialysis or oxygenation.     

Phaseolus vulgaris phytohemagglutinin contains high-mannose and modified oligosaccharide chains

Phytohemagglutinin, the major lectin in the seeds of the common bean Phaseolus vulgaris L., was isolated by affinity chromatography from cotyledons of nearly mature seeds and from developing cotyledons labeled with [³H]glucosamine, [³H]mannose or [³H]fucose. The protein was subjected to exhaustive proteolysis and the carbohydrate composition of the resulting glycopeptides examined. Two classes of oligosaccharide side-chains were found. The sidechains of the first class are of the high-mannose type, containing two residues of N-acetylglucosamine and 8 or 9 mannose residues. The sidechains of the second class are of the modified type containing N-acetylglucosamine, mannose, fucose, xylose in molar ratios of 2:3.8:0.6:0.5. Two-dimensional gel electrophoresis shows that phytohemagglutinin can be fractionated into seven different glycosylated polypeptides, and that each one contains at least one modified oligosaccharide chain. The results indicate that most glycosylated polypeptides probably contain one chain of each class. The carbohydrate composition of the two types of chains is similar to that found in other plant glycoproteins, but this is the first report of a plant glycoprotein with both highmannose and modified oligosaccharides on the same polypeptide chain.Abbreviations endo H endo--N-acetylglucosaminidase H - GlcN glucosamine - GlcNAc N-acetylglucosamine - Man mannose - PHA phytohemagglutinin This work was done while A.V. was on leave from the Istituto Biosintesi Vegetali, C.N.R., via Bassini 15, I-20133 Milano, Italy     

Synergistic effect of phosphatidylserine with γ-aminobutyric acid in antagonizing the isoniazid-induced convulsions in mice

The influence of phosphatidylserine (PS) on the isoniazid-induced convulsions has been studied in mice. Sonicated dispersions of this phospholipid given intravenously do not show anticonvulsant activity but they do so when -aminobutyric acid (GABA) is simultaneously injected. GABA alone is inactive. The synergism between PS and GABA is influenced by the structure of the phospholipid liposomes. In contrast to multilamellar vesicles, oligolamellar vesicles are active. Under these conditions the effect shows head group specificity, in that the neutral phosphatidylcholine (PC) or the acidic phosphatidylinositol (PI) are inactive, either in the presence or in the absence of GABA. Lysophosphatidylserine (lysoPS), the deacylated PS derivative, shows increased efficacy as an isoniazid antagonist in the presence of GABA, and has anticonvulsant activity also in the absence of GABA. Other lysophospholipids are inactive. It is suggested that PS, after its metabolic conversion to lysoPS, enhances the anticonvulsant effect of GABA.     

Correlation of cotylenol with the aglycone of fusicoccin

The stereostructure of cotylenol, the aglycone of the cotylenins, has been confirmed by chemical correlation with the aglycone of fusicoccin A.     

Action of sauvagine on the mesenteric vascular bed of the dog

Sauvagine, a linear peptide of 40 amino acids, produced hypotension when administered intravenously to anesthetized dogs. Diastolic pressure was always more affected than systolic pressure. Aortic blood flow and venous return both increased to the same extent. The mechanism of the hypotensive response was mainly, if not exclusively, due to dilatation of the superior and inferior mesenteric arteries. Intravenous infusion of sauvagine in doses ranging from 3 to 10 ng · kg^?1 · min^?1 produced a dose-related increased of mesenteric blood flow up to 400% control values. Mucosal-submucosal blood flow of ileum and colon was increased, while blood flow in muscle was unaffected or slight decreased. The mesenteric vasodilator response was not prevented by adrenergic or muscarinic receptor blockade. The hypotensive response was more marked and sustained in dibenamine-propranolol treated dogs.     

Syndrome +12p

Summary Familial 12/15 translocation with a child trisomic for the short arm of chromosome 12 (segment p 12.1pter) is reported. The clinical picture of the child is strikingly similar to previous reports of 12p trisomy. The main symptoms of 12p syndrome are defined.     

An improved approach for transformation of plant cells by microinjection: molecular and genetic analysis

A new culture method for the injection of tobacco mesophyll protoplasts has been established. The protoplasts are embedded in a thin layer of alginate and are nourished from the medium in the underlying basislayer. In the alginate layer the protoplasts regenerate to calli at a frequency of up to 80%. Embedded protoplasts can be selected either with 50 mg l⁻¹ kanamycin or 5 mg l⁻¹ paromomycin. Single resistant cells can be recovered from about 10 000 sensitive cells in one alginate layer. Injection of theneo gene (coding for neomycin phosphotransferase II) into protoplast derived single cells in the alginate layer results in kanamycin resistant colonies that can be regenerated to mature plants. These plants express the neomycin phosphotransferase as shown by enzyme activity assay. The integration of the transgene into the plant genome could be proved by Southern hybridization to high molecular weight DNA. With this culture method 100 cells can be injected per hour. Transformation frequencies range from 2 to 20%. In crossing experiments, it was shown that the foreign gene is transmitted to the next generation in a Mendelian fashion.