A novel haemoprotein induced by isosafrole pretreatment in the rat

The relationship between the initial rates of respiration dependent calcium transport by isolated rabbit cardiac mitochondria and the free calcium concentration of the reaction media has been examined at 10°C and 25°C. Initial rates of calcium transport were determined using an adaption of the EGTA/ruthenium red quench technique described by Reed and Bygrave (5). At 10°C the initial rate of calcium transport was found to be a sigmoidal function of free calcium concentration, with a Hill coefficient of approximately 1.9. Elevation of the temperature to 25°C produced a less sigmoidal relationship, the Hill coefficient being lowered to approximately 1.3.     

Relationship between the "phospholipid effect" and calcium in the thyroid. I. - Effects of calcium ions, E.G.T.A., ionophore A 23187, verapamil and chlorpromazine on resting and stimulate thyroid slices.

The "phospholipid effect" which is the enhanced turnover of the phosphorylinositol group of phosphatidylinositol (PI) occurs in the thyroid of response to thyreostimulin (TSH). The possibility that Ca2+ ions are involved in this stimulation has been investigated with pig thyroid slices. Experiments performed in media without Ca2+ or containing E.G.T.A. (2 mM), indicate that it is not the extracellular Ca2+ which is implied, but rather the intracellular Ca2+. The ionophore A23187 (6.10(-6) M) increases the specific radioactivity of the acid soluble precursors, but has also a specific effect on the PI turnover, which is additive with the effect of a high concentration of TSH (50 mU/ml). Washing and loading of slices with various Ca2+ concentrations show that 0.9 mM restores the TSH phospholipid effect. Verapamil (10(-3) M) and Chlorpromazine (10(-3) M) redirect glycerolipid metabolism by increasing PI and phosphatidic acid (PA) synthesis at the expense of other glycerolipids, as phosphatidylcholine (PC) and phosphatidylethanolamine (PE). These results suggest that the "phospholipid effect" is not a result of Ca2+ entry into the thyroid cells. On the contrary, it seems that this increased turnover of PI in "long term" incubations (3 hr). An additive and acute effect of TSH effect is more pronounced when Ca2+ movements     

Isolation of tumor disturbing factor on the proliferation of tumor cells in human serum

The classified sediment with ethanol from sera of nude mice and humans showed a disturbing effect on L1210 cells in vitro and a lifesaving effect on L1210 cell-bearing mice in vivo. This factor was purified more than 2300-fold to a specific activity of approximately 1 X 10(5) U/mg by ethanol classified precipitation, Sephadex G-200 gel filtration, DEAE cellulose ion exchange chromatography with Nacl and pH gradient aqueous solution, and preparative polyacrylamide gel electrophoresis.     

Aphidicolin does not inhibit the repair synthesis of mitotic chromosomes

In order to determine the possible role of α-polymerase in repair synthesis, we measured the unscheduled DNA synthesis stimulated by UV-irradiation in mitotic HeLa cells in the presence of Aphidicolin, a specific inhibitor of this enzyme. The results do not show any inhibition of the unscheduled DNA synthesis,indicating that the function of α-polymerase is not essential for repair synthesis of mitotic cells.     

Interactions between beta-ecdysone and fat body during wing disk development in vitro

We have investigated the actions of beta-ecdysone and fat body on wing disks of Plodia interpunctella in a series of sequential incubations in vitro. These experiments revealed that extended treatment times of beta-ecdysone at concentrations of 0·5 μg/ml or greater inhibited development of disks, and confirm that the presence of a fat body factor in the culture medium prevents this inhibition.     

Characterization and physico-chemical properties of human transcortin]

The molecular weight of human transcortin, calculated from the sedimentation coefficient, was found to be 49,500, thus slightly lower than previously reported values. After purification, human transcortin trended to polymerize rapidly, with participation of both non covalent bonds and one disulfide bridge per dimer. The physicochemical parameters, the amino-acid and carbohydrate composition were determined; its stability was studied under different conditions. Preliminary structural studies showed that the N-terminal sequence of the polypeptide chain was: Met-Asp-Pro-Asn-Ala-Ala-Tyr-Val and that the C-terminal amino acid was leucine.     

Electron spin resonance characterization of Chromatium D hemes,non-heme irons and the components involved in primary photochemistry

The combination of redox potentiometry with low temperature electron spin resonance (ESR) spectroscopy has led to further characterization of electron transfer components of Chromatium D. These include the readily buffer-soluble cytochromes c₅₅₃ and c′ and the high-potential iron-sulfur protein in the isolated state and associated with the chromatophore membrane. Buffer-insoluble cytochrome c₅₅₃, cytochro—me c₅₅₅, bacteriochlorophyll and the primary electron acceptor have been characterized both in the chromatophore membrane and also in a sodium dodecylsulfate detergent-solubilized subchromatophore preparation. Two iron-sulfur proteins have been revealed which are present in the chromatophore membrane but are released on treatment with sodium dodecylsulfate. They have central g values at 1.90 and 1.94 and have estimated midpoint potentials at pH 7.4 (E_m7·4) at +280 mV and ?100 mV, respectively, when associated with the chromatophore.In the membrane associated state the apparent E_m of cytochrome c′ is approximately 200 mV more positive than the E_m values reported for the free state; this implies either that the reduced form of cytochrome c′ binds to the membrane (or to a component therein) to a degree which is > 10³ times greater than that of the oxidized form or that the E_m shift results from membrane solvation. In the case of the high-potential iron-sulfur protein however, its E_m when associated with the chromatophore membrane is similar to that reported in the isolated state. The light-induced oxidation of the high-potential iron-sulfur protein at room temperature appears to be linked only to the oxidation of cytochrome c₅₅₅; it could serve as an electron pool in equilibrium with cytochrome c₅₅₅ in the cyclic electron flow system.The redox component defined in the reduced state by its g_y = 1.82 and g_x = 1.62 ESR spectrum satisfies the following criteria for its identification as the primary electron acceptor of P883. (a) The E_m7·4 value of the g = 1.82 component is ?120 ± 25mV. (b) At ?70 mV, where the g = 1.82 component is mainly oxidized in the dark, brief illumination at low temperature which causes the irreversible oxidation of one cytochrome c₅₅₃ heme, also induces the permanent reduction of the g = 1.82 component; the extent of reduction after brief illumination, given by the g = 1.82 signal height, is the same as that induced chemically at ?270 mV showing it to be fully reduced by the receipt of a single electron. (c) At more positive potentials where cytochrome c₅₅₃ is oxidized and is not involved in low-temperature reactions, the light-induced low-temperature kinetics of the g = 1.82 signal are reversible; the flash-induced g = 1.82 formation and subsequent dark decay are the same as those for the flash-induced P⁺883 (g = 2) formation and dark decay. We suggest that until a full physical-chemical characterization is completed this g = 1.82 component be designated “photoredoxin”.     

On the decay of lateral phase separations in biological membranes

A theory for the decay of a lateral phase separation in a biological membrane has been developed based upon the edge decay of a population of circular molecular domains of uniform size. The theory has been applied to the case of vesicle fusion at a presynaptic membrane. It is shown that the efficiency of fusion decays exponentially in time with a rate constant $\text{solπ}\text{2τ}\text{N}{}^{\mathrm{<mtext>1</mtext><mtext>2</mtext>}}$ which decreases as the rate at which bonds are broken within each domain (τ^?1) decreases and as the number of molecules within each domain (N) increases. Moreover, it has been speculated that this mechanism may offer in part an explanation for the slow, exponential decay during post-tetanic potentiation where it is known that the efficiency of neurotransmitter release at the presynaptic membrane is rate-controlling and decays exponentially.     

The effect of catecholamines on ion transport in the toad bladder

Noradrenalin (8 · 10⁻⁶ M) and adrenalin (6 · 10⁻⁶ and 6 · 10⁻⁷ M) were found to cause marked stimulation of short-circuit current (S.C.C.) in isolated toad bladder, but isoprenalin (8 · 10⁻⁷ M) was found to be without effect. The percentage rise in S.C.C. due to noradrenalin was found to be inversely proportional to the initial S.C.C. or total conductance of the bladder. Again in the case of noradrenalin the rise in S.C.C. was almost completely abolished by α-adrenergic blockade but not by β-blockade. This rise in S.C.C. was found not to be significantly different from the rise in net Na⁺ flux. Bidirectional Cl⁻ fluxes were estimated using ⁸²Br as a companion radionuclide to ³⁶Cl. No significant net Cl⁻ flux was apparent, either before or after addition of any of the three catecholamines tested. However, in some cases the unidirectional Cl⁻ fluxes rose markedly following addition of noradrenalin or of adrenalin and this change was not reflected in a change in total conductance. This anomaly was noted to occur in bladders whose initial conductance was of the order of 0.5 kΩ⁻¹ · cm⁻² or greater. The evidence presented suggests that two actions of catecholamines on ion transport in toad bladder are (a) to increase Na⁺ transport via stimulation of α-adrenergic sites and (b) at the concentrations tested to cause an increase in passive Cl permeability in bladders whose initial conductance is high.     

Elongated cells derived from rat mammary cuboidal epithelial cell lines resemble cultured mesenchymal cells in their pattern of protein synthesis

Two-dimensional gel electrophoresis has been used to identify polypeptide patterns characteristic of rat mammary cuboidal epithelial cells or mesenchyme-derived cells. Elongated cells and cell lines derived from cloned cuboidal epithelial cells in culture possess a polypeptide pattern which resembles that of the cultured mesenchymal cells rather than that of the cuboidal epithelial cells from which they were derived. These elongated converts also resemble cultured mesenchymal cells in possessing a Triton-insoluble matrix in which vimentin and not prekeratin predominates.     

Interêts du dosage des adénosines 5′-phosphate pour l'étude de la dynamique des populations phytoplanctoniques lacustres (le Pavin - France)

A study on A.T.P., A.D.P. and A.M.P. in the phytoplankton of Lake Pavin was carried out from November 1976 to December 1977. Samples were collected at nine depths, between the surface and 50 m.A.T.P., A.D.P. and ( = A.T.P.+ A.D.P. + A.M.P.) show a similar behaviour in space and time but A.M.P. behaves independently. The A.M.P. concentration is high only when primary production of phytoplankton is high.The energy charge [CE = (ATP + % MathType!MTEF!2!1!+-% feaafiart1ev1aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn% hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr% 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq-Jc9% vqaqpepm0xbba9pwe9Q8fs0-yqaqpepae9pg0FirpepeKkFr0xfr-x% fr-xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaWaaSGaaeaaca% aIXaaabaGaaGOmaaaaaaa!3776!\[{\raise0.7ex\hbox{$1$} \!\mathord{\left/ {\vphantom {1 2}}\right.\kern-\nulldelimiterspace}\!\lower0.7ex\hbox{$2$}}\]ADP)/(ATP + ADP + AMP)] could be used as measure of adaptation in algal populations. Indeed, the energy charge increases as algal cells experience difficulty in maintaining themselves in the biotope.

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Interêts du dosage des adénosines 5-phosphate pour l'étude de la dynamique des populations phytoplanctoniques lacustres (le Pavin - France)

     

Further studies on the effect of aldosterone on electrical resistance of toad bladder

The fall in transepithelial electrical resistance which accompanies aldosterone stimulation of short-circuit current ($\text{I}{}_{\mathrm{<mtext>sc</mtext>}}$) in toad urinary bladder has been studied further to evaluate the possible causal role of this response in hormonal stimulation of Na⁺ transport. A steady-state change in tissue conductance was found to depend upon both the simultaneous stimulation of transport by the steroid and the metabolic state of the tissue. Changes in metabolic state alone did not alter resistance. A sustained increase in Na⁺ transport, dependent on pretreatment with aldosterone and elicited by addition of glucose, could be obtained without a sustained decrease in resistance. Amiloride, an inhibitor of Na⁺ uptake, produced changes in $\text{I}{}_{\mathrm{<mtext>sc</mtext>}}$ that were linearly correlated with its effects on tissue conductance. On the basis of the $\text{conductance}\text{-I}{}_{\mathrm{<mtext>sc</mtext>}}$ relationship with amiloride, the $\text{I}{}_{\mathrm{<mtext>sc</mtext>}}$ response to aldosterone was about two-fold higher than would be predicted from its effects on conductance alone. Despite the apparent lack of a simple quantitative dependence of the change in $\text{I}{}_{\mathrm{<mtext>sc</mtext>}}$ on the change in conductance when the response is fully developed, the results suggest that conductance changes may mediate the initial or early stage of the response.     

Effect of sanguinarine,a benzophenanthridine alkaloid,on frog skin potential difference and short circuit current

Sanguinarine, a benzophenanthridine alkaloid, causes an initial stimulation of frog skin short circuit current $\text{I}{}_{\mathrm{<mtext>sc</mtext>}}$ when present in the mucosal bathing medium at 10^?4 M. The stimulation is accompanied by an increase in spontaneous potential difference (PD) and increase in D.C. resistance. No effects are seen with sanguinarine in the serosal bathing medium. The initial stimulation is followed by a decrease in $\text{I}{}_{\mathrm{<mtext>se</mtext>}}$ and PD, but a continued increase in resistance. In skins whose initial spontaneous PD is high, no initial stimulation in ${}_{\mathrm{<mtext>se</mtext>}}$ and PD is seen; however, clamping these skins to a lower potential does not alter their initial inhibitory response to sanguinarine. Likewise, clamping the lower potential skins to higher potential does not alter their initial stimulatory response. Sanguinarine seems to be acting on the permeability barriers at the outer surface of the frog skin.     

Comparison of the effects of neuropeptide Y and adrenergic transmitters on LH release and food intake in male rats

In view of the recent demonstrations that Neuropeptide Y (NPY) and adrenergic transmitters coexist in neurons of the rat brain, we have compared the effects of intraventricular (Ivt) injections of NPY and catecholamines on LH release and food intake in intact male rats. Of the three catecholamines, dopamine (DA), norepinephrine (NE) and epinephrine (E), only E (5.3 micrograms or 15.9 micrograms/rat) significantly stimulated LH release, although NE and E (5.3 micrograms/rat) were equally effective in eliciting food intake in satiated rats. Ivt administration of 10 micrograms NPY significantly stimulated LH release, whereas either lower (0.5 or 2 micrograms/rat) or higher (25 micrograms/rat) doses were ineffective. In contrast, NPY at doses of 0.5 - 10 micrograms/rat increased cumulative food intake in a dose-related fashion. These findings present preliminary evidence of the physiological correlates of the neuronal coexistence of adrenergic transmitters and NPY in the brain and raise the possibility that NPY may normally act either independently, in concert with or via adrenergic systems to evoke LH release and feeding responses in the rat.     

柠檬酸行业清洁生产工艺的可行性分析

本文从技术和经济效益两方面来分析以玉米为原料所进行的柠檬酸清洁生产工艺的可行性。     

Conversion of methionine to homocysteine thiolactone in liver

Since hemocysteinemia is associated with arteriosclerosis, the conversion of methione to homocysteine thiolactone was studied in guinea pig liver in vivo. 60 min after intraperitoneal injection of [¹⁴C]methione, [¹⁴C]homocystein thiolactone was found to constitute 9.1% ± 0.2 of the lipid bound ¹⁴C and 20% ± 1.0 of the acid soluble ¹⁴C. This conversion is the first step of a new pathway by which the sulfur of methionine is transferred to phosphoadenosine phosphosulfate.     

The use of performic acid oxidation to facilitate differential staining of epoxy-embedded adenohypophysis

Summary Preoxidation with performic acid facilitated the differential staining of 1–2 thick sections of water-insoluble Durcupan (Swiss Araldite)-embedded adenohypophysis. Alcian blue-PAS-Orange G and aldehyde fuchsin-Orange G staining procedures were used. Except for increases in staining times, these procedures were unmodified from those previously reported for paraffin sections. These techniques permit the light microscopic recognition of two groups of basophils and two groups of acidophils in thick sections cut adjacent to thin sections for electron microscopy.