Effects of intracerebroventricular administration of aminophylline on hyperbaric-induced increase in carotid blood flow

Carotid blood flow was measured in rats by implanted transit-time ultrasonic flowprobes during hyperbaric experiments at up to 70 bar (7 MPa) using an helium-oxygen hyperoxic (partial pressure of O₂ = 400 mbar) mixture. Before the hyperbaric experiment, an intracerebroventricular injection of phosphate saline buffered solution (PBS) or aminophylline, an adenosine receptor blocker, in PBS was given. Throughout the hyperbaric experiment carotid blood flow increased with ambient pressure in both PBS, i.e. control, and aminophylline treated rats. The increase in carotid blood flow was significantly attenuated in aminophylline treated rats. Additional experiments showed that the increased carotid blood flow was independent of hyperoxia as well as of temperature. The hypothesis that the hyperbaric dependent increase in carotid blood flow was mediated by brain adenosine receptors and its implication regarding a cerebral vasodilatation are discussed.     

Nitrogen-fixing cyanobacteria as source of phycobiliprotein pigments. Composition and growth performance of ten filamentous heterocystous strains

Ten strains of filamentous, heterocystous nitrogen-fixing blue-green algae (cyanobacteria) were screened for growth performance and tolerance to temperature, pH, irradiance and salinity, together with their potential as producers of phycobiliprotein pigments. Phycobiliproteins typically accounted for about 50% total cell protein, the prevalent type being C-phycocyanin, followed by alloppycocyanin, with levels of 17 and 11% d.wt, respectively, in some strains of Anabaena and Nostoc. C-phycoerythrin was the major pigment in several Nostoc strains, reaching 10% d.wt. Some strains represent, therefore, excellent sources of one or more phycobiliproteins. All strains tolerated an irradiance of ca 2000 μmol photon m^-2 s^-1. Anabaena sp. ATCC 33047 and Nostoc sp. (Albufera) exhibited the widest optimum range of both temperature (30–45 and 25–40 °C) and pH (6.5–9.5 and 6.0–9.0) for growth, the former also showing significant salt tolerance. In an outdoor open system, productivity of cultures of two phycoerythrin-rich strains of Nostoc was over 20 g (d.wt) m^-2 d^-1 during summer. The growth performance of the allophycocyanin-rich Anabaena sp. ATCC 33047 in outdoor semi-continuous culture has been assessed throughout the year. Productivity values under optimized conditions ranged from 9 (winter) to 24 (summer) g (d.wt) m^-2 d^-1.     

Glycoproteins in bacterial membranes. In vivo labeling of the sugar portion of energy-transducing ATPase and a low-molecular-weight fraction fromMicrococcus lysodeikticus membranes

The energy-transducing ATPase and a low-molecular-weight fraction ofMicrococcus lysodeikticus membranes incorporated¹⁴C label fromd-[U-¹⁴C]glucose fed to the bacteria in synthetic medium. The specific radioactivity of the sugar portion of the ATPase and low-molecular-weight fraction was, respectively, 2.65 and 2.88 times that of their amino acids. Glucose and mannose in approximately equimolar amounts were identified as the main sugars of the glycoprotein ATPase, thus confirming previous structural studies. Glucose, galactose, and mannose (1:1:2) were identified as the main sugars of the low-molecular-weight glycopeptides. These results confirm and extend the notion that glycoprotein are constituents of prokaryotic membranes.     

Effect of corticosteroids on the congenital transmission of experimental toxoplasmosis]

Female white mice with chronic toxoplasmosis were treated with cortisone acetate (3mg for each 25 g of body weight) 12, 8, 4 and 0 days before mating. Cortisone induces congenital transmission of T. gondii.     

Reactor design for the enzymatic isomerization of glucose to fructose

A comprehensive methodology is presented for the design of reactors using immobilized enzymes as catalysts. The design is based on material balances and rate equations for enzyme action and decay and considers the effect of mass transfer limitations on the expression of enzyme activity. The enzymatic isomerization of glucose into fructose with a commercial immobilized glucose isomerase was selected as a case study. Results obtained are consistent with data obtained from existing high-fructose syrup plants. The methodology may be extended to other cases, provided sound expressions for enzyme action and decay are available and a simple flow pattern within the reactor might be assumed.List of Symbols C kat/kg specific activity of the catalyst - D m²/s substrate diffusivity within the catalyst particle - Dr m reactor diameter - d d operating time of each reactor - E kat initial enzyme activity - E _i kat initial enzyme activity in each reactor - F m³/s process flowrate - F _i m³/s reactor feed flowrate at a given time - F ₀ m³/s initial feed flowrate to each reactor - H number of enzyme half-lives used in the reactors - K mole/m³ equilibrium constant - K _S mole/m³ Michaelis constant for substrate - K _P mole/m³ Michaelis constant for product - K _m mole/m³ apparent Michaelis constant f(K, K _s, K_p, s₀) - k mole/s · kat reaction rate constant - k _d d^–1 first-order thermal inactivation rate constant - L m reactor height - L _r m height of catalyst bed - N _R number of reactors - P _i kg catalyst weight in each reactor - p mole/m³ product concentration - R m particle radius - R _P ratio of minimum to maximum process flowrate - r m distance to the center of the spherical particle - s mole/m³ substrate concentration - s _0i mole/m³ substrate concentration at reactor inlet - s ₀ mole/m³ bulk substrate concentration - s mole/m³ apparent substrate concentration - T K temperature - t d time - t _i d operating time for reactor i - t _s d time elapsed between two successive charges of each reactor - V m³ reactor volumen - V _m mole/m³ s maximum apparent reaction rate - V _p mole/m³ s maximum reaction rate for product - V _R m³ actual volume of catalyst bed - V _r m³ calculated volume of catalyst bed - V _S mol/m³ s maximum reaction rate for substrate - v mol/m³ s initial reaction rate - v _i m/s linear velocity - v _m mol/m³ s apparent initial reaction rate f(K_m, s,V_m) - X substrate conversion - X _eq substrate conversion at equilibrium - =s/K dimensionless substrate concentration - ₀=s₀/K bulk dimensionless substrate concentration - _eq=s_eq/K dimensionless substrate concentration at equilibrium - local effectiveness factor - mean integrated effectiveness factor - Thiéle modulus - =r/R dimensionless radius - _s kg/m³ hydrated support density - substrate protection factor - s residence time     

DNA map of mutations at the scute locus of Drosophila melanogaster

The achaete-scute gene complex (AS-C) of Drosophila melanogaster is involved in the differentiation of innervated elements in the adult (chaetes) and in the embryo (central nervous system). Genetically, the AS-C is subdivided into four regions: achaete, scute α, lethal of scute, and scute β. Using a previously cloned fragment of scute DNA, we have now cloned 62 kb of wild-type DNA from the scute region. No repetitive sequences have been detected in this stretch of DNA. Of 16 scute mutants with chromosomal rearrangements studied (inversions, deletions, and translocations), nine, included genetically in scute β, have breakpoints in the cloned region. The remaining rearrangements, which genetically correspond to scute α, map outside and to the left of the cloned region. Of nine scute `point mutants' studied, eight have large DNA alterations within the cloned region. These alterations include insertions (five) and deletions (three). The DNA alterations found in both `point mutants' and rearrangements are interspersed and scattered over 40 kb. The relationship between the sites of the DNA alterations and the mutant phenotypes are discussed.     

Affinity chromatography of Anacystis nidulans ferredoxin nitrate reductase and NADP reductase on reduced ferredoxin-Sepharose.

The behavior of two ferredoxin-dependent enzymes—nitrate reductase and NADP reductase—fromAnacystis nidulans on a ferredoxin-Sepharose gel was examined. The oxidized gel-bound ferredoxin exhibited very low affinity for these enzymes but effectively bound both nitrate reductase and NADP reductase when reduced by dithionite. Selective procedures are described for the clution of each of these two enzymes from the reduced ferredoxin-Sepharose gel. These simple methods allow substantial purification of both enzymes.     

Melanoma RBPome identification reveals PDIA6 as an unconventional RNA-binding protein involved in metastasis

RNA-binding proteins (RBPs) have been relatively overlooked in cancer research despite their contribution to virtually every cancer hallmark. Here, we use RNA interactome capture (RIC) to characterize the melanoma RBPome and uncover novel RBPs involved in melanoma progression. Comparison of RIC profiles of a non-tumoral versus a metastatic cell line revealed prevalent changes in RNA-binding capacities that were not associated with changes in RBP levels. Extensive functional validation of a selected group of 24 RBPs using five different in vitro assays unveiled unanticipated roles of RBPs in melanoma malignancy. As proof-of-principle we focused on PDIA6, an ER-lumen chaperone that displayed a novel RNA-binding activity. We show that PDIA6 is involved in metastatic progression, map its RNA-binding domain, and find that RNA binding is required for PDIA6 tumorigenic properties. These results exemplify how RIC technologies can be harnessed to uncover novel vulnerabilities of cancer cells.