The effect of a pattern in palmar interdigital II on a-b ridge count in black and white Down syndrome cases and controls

An unconfirmed study by Fang (Ph.D. thesis, Univ. of London, 1950) in Britain showed that individuals with Down syndrome had lower total a-b ridge counts in palmar Interdigital area II (ID II) than a group of controls. This study compares 603 white Down syndrome cases and 93 black Down syndrome cases with 668 white and 402 black controls. Our results confirm those of Fang in that the Down syndrome cases in both racial groups had lower total a-b ridge counts than their respective controls. In addition, the black controls and Down syndrome cases had lower a-b ridge counts than their white counterparts. The mean a-b ridge count was significantly lower in individuals with a pattern in ID II compared to individuals without a pattern in ID II in both the Down syndrome and control groups. Some of the lower a-b ridge counts in the Down syndrome samples can be accounted for by the fact that there is an increased frequency of a pattern in ID II in Down syndrome cases. Both Down syndrome and normal individuals who had a pattern unilaterally had a lower than expected a-b ridge count on the contralateral hand that did not have a pattern. There was a tendency also for increased asymmetry in Down syndrome cases with a pattern in ID II.     

Localization of vasopressin,serotonin and angiotensin II in endothelial cells of the renal and mesenteric arteries of the rat

Summary The localization of vasopressin, serotonin and angiotensin II in the endothelial cells of renal and mesenteric arteries was investigated using the pre-embedding peroxidase-antiperoxidase technique for electron microscopy. Vasopressin-and serotonin-positive endothelial cells were present in both renal and mesenteric arteries while angiotensin II-positive cells were observed in the mesenteric artery exclusively. Both arteries showed less than 10% immunoreactive cells. The lack of angiotensin II in the endothelial cells of the renal artery suggests that there may be subtle physiological differences between the renal and mesenteric arteries with respect to the local control of blood flow.     

Production of novel pullulanases at high concentrations by two newly isolated thermophilic clostridia

Two thermophilic bacteria, which are capable of growing on starch at 60-70 degrees C under anaerobic conditions, were isolated from a sugar refinery in Uelzen and from Solar lake in Israel. On the basis of their physiological characteristics they were identified as Clostridium thermohydrosulfuricum Uel 1 and C. thermohydrosulfuricum Sol 1, respectively. The product pattern of glucose polymer hydrolysis showed that both strains secreted enzymes that possess amylolytic and pullulytic activities. The major product formed was maltose. In addition, alpha-glucosidase activity could be detected in the supernatants of Uel 1 strain. Compared to most anaerobes investigated these isolates secreted extremely high concentrations of pullulanases in batch culture. Up to 85% of the total enzyme synthesized was detected in the culture fluid. Unlike the pullulanases of type I, which can only attack the alpha-1,6-glycosidic linkages, the pullulanases of both clostridial strains were also capable of hydrolyzing alpha-1,4-linkages. The enzyme system of both bacteria was found to be highly thermoactive; optimal activity was detected at pH 5.0 and 85 degrees C. Even at 95 degrees C and without the addition of metal ions still 15% to 25% of enzymatic activity was detectable.     

A practical test for in vitro evaluation of photosensitization: Assessment with hematoporphyrin derivative (HPD)

A simple procedure is described for the determination of the photosensitizing potency of drugs, using three leukemic cell lines, two of lymphocytic origin, L1210 and P388 and one of erythroid type, Friend-745. The procedure allows one to investigate several aspects of the photosensitization properties of tested compounds such as cellular localization and direct (trypan blue exclusion) or delayed (clonogenicity) photomediated toxicities.The method was assessed using crude hematoporphyrin derivative (HPD) as well as dihematoporphyrin ether (DHE) or commercially available Photofrin II. Results were compared to those obtained with normal cells, e.g spleen lymphocytes and erythropoietic stem cells (CFU-e), and discussed in the light of the relative response of normal versus transformed cells.Abbreviations DHE Dihematoporphyrin Ether - FCS Fetal Calf Serum - HPD Hematoporphyrin Derivative - PDT Photodynamic Therapy     

Binding of azide and thiocyanate ligands to copper(II) model complexes

Summary Binding of azide to a series of copper(II) complexes has been investigated by absorption, CD and EPR spectroscopy. Axial binding of azide to Cu(II) can be differentiated from equatorial binding through the lower intensity and lack of optical activity of the LMCT band. The affinity of azide for Cu(II) increases with the overall positive charge of the complex. The preliminary data on thiocyanate binding to Cu(II) seem to agree with the trends observed for the corresponding azide adducts.     

An improved purification procedure and properties of casein kinase II from brain

A simple and short purification procedure applicable to casein kinase II has been developed, for fully characterizing the enzyme from calf cerebral cortex cytosol. The procedure consists of four chromatographic steps: DEAE-cellulose, phosphocellulose, phosvitin-Sepharose and ATP-agarose which yields 87% pure casein kinase II. The purified enzyme shows three major bands with apparent molecular masses of 42, 38, and 27 kDa by polyacrylamide gel electrophoresis in sodium dodecyl sulfate and is self-autophosphorylated on its 27 kDa polypeptide. The enzyme shows all the characteristics described for casein kinase II from other sources: it is independent of cyclic nucleotides, calcium/phospholipids, and double-stranded poly(I).poly(C); it can utilize both ATP and GTP as phosphoryl donors and can phosphorylate both casein and phosvitin but not histone. The kinetic studies establish that theK _m for ATP is 12.5 M and 25.1 M when using phosvitin and casein respectively as phosphoryl acceptors. TheK _m for phosvitin is 0.91 mg/ml and for casein 1.43 mg/ml, while theV _max is 315 nmol/min/per mg protein and 479 nmol/min/per mg protein for phosvitin and casein respectively. The activity of the kinase is highly stimulated by KCl or NaCl, and almost completely inhibited by heparin concentrations of 1 g/ml (92%). This inhibition is reduced to only 33% in the presence of optimal KCl concentrations (150 mM). Spermine stimulates enzyme activity, whilst hemin produces a slight inhibition.     

Analysis of the Escherichia coli glycogen gene cluster suggests that catabolic enzymes are encoded among the biosynthetic genes

The nucleotide sequences of the Escherichia coli genome between the glycogen biosynthetic genes glgB and glgC, and 1170 bp of DNA which follows glgA have been determined. The region between glgB and glgC contains an open reading frame (ORF) of 1521 bp which we call glgX. This ORF is capable of coding for an M_r 56 684 protein. The deduced amino acid (aa) sequence for the putative product shows significant similarity to the E. coli glycogen branching enzyme, and to several different glucan hydrolases and transferases. The regions of sequence similarity include residues which have been reported to be involved in substrate binding and catalysis by taka-amylase. This suggests that the proposed product may catalyze hydrolysis or glycosyltransferase reactions. The cloned region which follows glgA contains an incomplete ORF (1149 bp), glgY, which appears to encode 383 aa of the N terminus of glycogen phosphorylase, based upon sequence similarity with the enzyme from rabbit muscle (47% identical aa residues) and with maltodextrin phosphorylase from E. coli (37% identical aa residues). Results suggest that neither ORF is required for glycogen biosynthesis. The localization of glycogen biosynthetic and degradative genes together in a cluster may facilitate the regulation of these systems in vivo.     

The molecular mechanism of the bicarbonate effect at the plastoquinone reductase site of photosynthesis

It has been known for some time that bicarbonate reverses the inhibition, by formate under HCO₃ ^--depletion conditions, of electron transport in thylakoid membranes. It has been shown that the major effect is on the electron acceptor side of photosystem II, at the site of plastoquinone reduction. After presenting a historical introduction, and a minireview of the bicarbonate effect, we present a hypothesis on how HCO₃ ^- functions in vivo as (a) a proton donor to the plastoquinone reductase site in the D1-D2 protein; and (b) a ligand to Fe²⁺ in the Q_A-Fe-Q_B complex that keeps the D1-D2 proteins in their proper functional conformation. They key points of the hypothesis are: (1) HCO₃ ^- forms a salt bridge between Fe²⁺ and the D2 protein. The carboxyl group of HCO₃ ^- is a bidentate ligand to Fe²⁺, while the hydroxyl group H-bonds to a protein residue. (2) A second HCO₃ ^- is involved in protonating a histidine near the Q_B site to stabilize the negative charge on Q_B. HCO₃ ^- provides a rapidly available source of H⁺ for this purpose. (3) After donation of a H⁺, CO₃ ^2- is replaced by another HCO₃ ^-. The high pKa of CO₃ ^2- ensures rapid reprotonation from the bulk phase. (4) An intramembrane pool of HCO₃ ^- is in equilibrium with a large number of low affinity sites. This pool is a H⁺ buffering domain functionally connecting the external bulk phase with the quinones. The low affinity sites buffer the intrathylakoid [HCO₃ ^-] against fluctuations in the intracellular CO₂. (5) Low pH and high ionic strength are suggested to disrupt the HCO₃ ^- salt bridge between Fe²⁺ and D₂. The resulting conformational change exposes the intramembrane HCO₃ ^- pool and low affinity sites to the bulk phase.Two contrasting hypotheses for the action of formate are: (a) it functions to remove bicarbonate, and the low electron transport left in such samples is due to the left-over (or endogenous) bicarbonate in the system; or (b) bicarbonate is less of an inhibitor and so appears to relieve the inhibition by formate. Hypothesis (a) implies that HCO₃ ^- is an essential requirement for electron transport through the plastoquinones (bound plastoquinones Q_A and Q_B and the plastoquinone pool) of photosystem II. Hypothesis (b) implies that HCO₃ ^- does not play any significant role in vivo. Our conclusion is that hypothesis (a) is correct and HCO₃ ^- is an essential requirement for electron transport on the electron acceptor side of PS II. This is based on several observations: (i) since HCO₃ ^-, not CO₂, is the active species involved (Blubaugh and Govindjee 1986), the calculated concentration of this species (220 M at pH 8, pH of the stroma) is much higher than the calculated dissociation constant (Kd) of 35–60 M; thus, the likelihood of bound HCO₃ ^- in ambient air is high; (ii) studies on HCO₃ ^- effect in thylakoid samples with different chlorophyll concentrations suggest that the left-over (or endogenous) electron flow in bicarbonate-depleted chloroplasts is due to left-over (or endogenous) HCO₃ ^- remaining bound to the system (Blubaugh 1987).Abbreviations DCMU 3-(3,4-dichlorophenyl)-1, 1-dimethylurea (common name: diuron) - PSII photosystem II - Q_A first plastoquinone electron acceptor of PSII - Q_B second plastoquinone acceptor of PS II     

Point mutations in the 23 S rRNA genes of four lincomycin resistant Nicotiana plumbaginifolia mutants could provide new selectable markers for chloroplast transformation

Summary Experiments designed to establish stable chloroplast transformation require selectable marker genes encoded by the chloroplast genome. The antibiotic lincomycin is a specific inhibitor of chloroplast ribosomal activity and is known to bind to the large ribosomal subunit. We have investigated a defined region of the chloroplast 23 S rRNA genes from four lincomycin resistant Nicotiana plumbaginifolia mutants and from wild-type N. plumbaginifolia. The mutants LR415, LR421 and LR446 have A to G transitions at positions equivalent to the nucleotides 2058 and 2059 in the Escherichia coli 23 S rRNA. The mutant, LR400, possesses a G to A transition at a position corresponding to nucleotide 2032 of the E. coli 23 S rRNA.