Tetanus responses under rapid bath solution change: Electrotonic depolarization of transverse tubules may release Ca2+ from sarcoplasmic reticulum of Rana japonica skeletal muscle

• 1.1. Single skeletal muscle fibers were transferred from a normal Ringer solution to Na⁺ ion free solution, and vice versa, and tetanus responses were recorded immediately after the transfer.
• 2.2. Fractional tetanus tension recorded immediately after the displacement from the Na⁺ ion free solution to normal Ringer solution was dependent on fiber diameter.
• 3.3. Diffusion of Na⁺ ions along the transverse tubules was simulated [apparent diffusion constant was 3.11 × 10⁻⁶ (cm²/s)].
• 4.4. Our results suggest that the electrotonic spreading of membrane potential, caused by an action potential in the transverse tubules, could release Ca²⁺ ions from sarcoplasmic reticulum.

     

Analysis of peptide biosynthesis in the neurointermediate lobe of Xenopus laevis using high-performance liquid chromatography: occurrence of small bioactive products

• 1.1. Ppeitde biosynthesis in neurointermediate lobes of black adapted Xenopus laevis was studied using pulse-chase incubation and reversed-phase, high-performance liquid chromatographic analysis.
• 2.2. During the pulse period one major product was synthesized, which was subsequently converted to 12 chase peptides, suggesting a precursor-product mode of biosynthesis for this tissue.
• 3.3. Chase peptides I, II and IV possessed high melanotropic activity. Alpha-MSH did not appear to be among the chase peptides. Peptide II had also high corticotropic activity.
• 4.4. Peptides I and II are probably small, since they were TCA-soluble and ran faster on acid-urea gels than α-MSH. They may, however, well be structurally related to this latter hormone.

     

A comparative study of nuclear and chloroplast DNA dependent RNA polymerases from wheat leaves

• 1.1. Three DNA dependent RNA polymerases have been purified from chromatin and chloroplast fractions of wheat leaves.
• 2.2. The purified enzymes were completely dependent on exogenous DNA after purification by glycerol gradient, DEAE-Sephadex and phosphocellulose chromatography.
• 3.3. The nuclear enzymes, I and II, showed a strong preference for denatured nuclear DNA, whereas the chloroplast enzyme preferred denatured chloroplast DNA.
• 4.4. The three enzymes require either Mg²⁺ or Mn²⁺ for activity.
• 5.5. α-amanitin specifically inhibited RNA polymerase II but has no effect on polymerase I and chloroplast polymerase.
• 6.6. Enzyme I is most active at very low ionic strength (0.10 mM KC1), whereas enzyme II and chloroplast enzyme show maximum activity at 150mM and 50 mM KC1 respectively.

     

Effects of the nonsteroidal anti-inflammatory drug piroxicam on energy metabolism in the perfused rat liver

• 1.1. The actions of piroxicam, a nonsteroidal and noncarboxylic anti-inflammatory drug, on the metabolism of the isolated perfused rat liver were investigated. The main purpose was to verify if piroxicam is also active on glycogenolysis and energy metabolism, as demonstrated for several carboxylic nonsteroidal anti-inflammatories.
• 2.2. Piroxicam increased oxygen consumption in livers from both fed and fasted rats.
• 3.3. Piroxicam increased glucose release and glycolysis from endogenous glycogen (glycogenolysis).
• 4.4. Gluconeogenesis from lactate plus pyruvate was inhibited.
• 5.5. The action of piroxicam on oxygen consumption was blocked by antimycin A, but not by atractyloside.
• 6.6. The action of piroxicam in the perfused rat liver metabolism seems to be a consequence of its action on mitochondria.
• 7.7. It can be concluded that inhibition of energy metabolism and stimulation of glycogenolysis are not specific properties of carboxylic nonsteroidal anti-inflammatory drugs.

     

δ-Aminolevulinic acid dehydratase inactivation by uroporphyrin I in light and darkness

• 1.1. The action of uroporphyrin I on erythrocytic ALA-D activity under dark and light conditions was examined.
• 2.2. Photo and non-photoinactivation of ALA-D induced by uroporphyrin I were observed.
• 3.3. Both effects were dependent on uroporphyrin concentration, temperature and time of exposure of the protein to the porphyrin.
• 4.4. Light-dependent effect of uroporphyrin I is related with the phototoxicity of porphyrins and could be produced by primary amino acid photooxidation followed by secondary cross-linking of the protein.
• 5.5. Light-dependent effect of uroporphyrin I could be ascribed to a direct enzyme inhibition due to binding of the porphyrin to the protein inducing structural changes at or near its active site.

     

Monoclonal antibodies prepared against heparin lyase I and their reactivity toward heparin lyase I,II and III

• 1.1. Six different monoclonal IgG mouse antibodies to heparin lyase I from Flavobacterium heparinum were prepared.
• 2.2. The monoclonal antibodies were used to detect heparin lyases I, II and III by dot-blotting immunoassay and by Western blotting.
• 3.3. Individual antibodies showed different reactivity toward the three heparin lyases.
• 4.4. The reactivity of two of the monoclonal antibodies was destroyed by exposing heparin lyases to sodium dodecyl sulfate.
• 5.5. The antibodies can be used to rapidly distinguish between the three heparin lyases.

     

Bioelectric activity from isolated brain of Lacerta atlantica

• 1.1. A method of maintaining the isolated lizard brain in a Ringer solution is described.
• 2.2. Microelectrodes and EEG recordings from different areas of telecenphalon and optical tectum were made.
• 3.3. The prolonged cells survival under the experimental conditions described has been demonstrated for several hours.
• 4.4. The isolated brain of Lacerta makes it easy to reach anatomical pathways which otherwise, in the whole animal, would be more difficult to reach.

     

Properties and topology of enzymes methylating phosphatidylethanolamine to phosphatidylcholine in sarcoplasmic reticulum

• 1.1. The synthesis of phosphatidylcholine (PC) by stepwise methylation of phosphatidylethanolamine (PE) is carried out by two enzymes in sarcoplasmic reticulum (SR) membrane of rabbit fast-twitch skeletal muscles.
• 2.2. Two methyltransferases (Met I and Met II) have a different pH optimum and affinity for methyl donor—5-adenosyl-L-methionine (SAM).
• 3.3. Met I is an integral SR membrane protein which active site faces the cytoplasmic surface of the membrane.
• 4.4. Met II is a peripheral, loosely bound protein, localized mainly on the extracytoplasmic (luminal) part of the SR membrane.

     

Demonstration of specific receptors for calcitonin in isolated trout gill cells

• 1.1. Salmon calcitonin binding by isolated gill cells from rainbow trout, Salmo gairdneri has been investigated.
• 2.2. The calcitonin receptor interaction is time- and temperature-dependent.
• 3.3. 50% of inhibition of the ¹²⁵I labeled calcitonin binding is observed in presence of 1.5 ng/ml unlabeled salmon calcitonin.
• 4.4. Two types of receptors are described: a high affinity-low capacity site and a low affinity-large capacity site.
• 5.5. These studies strongly support the role of calcitonin as a hormone regulating the gill function in physiological conditions.

     

Comparative hematology: Studies on cats including one with factor XII (hageman) deficiency

• 1.1. Cat plasma prothrombin and partial thromboplastin times are faster than human. Thromboplastin generation tests are very similar.
• 2.2. Factors VIII and V assay 24 and 13 times the human standard. Cat factors VII, X. IX, XI and XII assayed at 2.5 to 4 times human. Factors I, II and XIII fell within the human range and Fletcher was extremely low.
• 3.3. One cat lacked factor XII and showed a prolonged APTT and clotting time.
• 4.4. Cat profibrinolysin was activated by streptokinase but not by urokinase.
• 5.5. Cat platelets aggregated with the usual human aggregation agents with the exception of thrombin and ristocetin.
• 6.6. Cat erythrocytes were smaller and more numerous than human.
• 7.7. Leukocyte counts were quite variable.
• 8.8. Serum protein electrophoretic patterns differed from human in the greater migration of albumin and the presence of numerous unidentified bands.
• 9.9. Biochemical tests showed high sodium and chloride values.

     

Rat liver endoplasmic reticulum protein kinases

• 1.1. Rat liver microsomal membranes were studied for the presence of protein kinases. Microsomal proteins solubilized with Triton X-100 were analyzed by means of ion exchange chromatography.
• 2.2. Protein kinase activity was detected in the column fractions using specific assays for cAMP-dependent protein kinase, cGMP-dependent protein kinase, protein kinase C, Ca²⁺/calmodulin-dependent protein kinase and casein kinases.
• 3.3. Fractions with protein kinase activity were further analyzed by SDS-polyacrylamide gel electrophoresis.
• 4.4. The results indicate that cAMP-dependent protein kinase type I and II, casein kinases I and II, protein kinase C proenzymes I and II and Ca²⁺ /calmodulin kinase II are associated with the membranes of endoplasmic reticulum (ER).

     

Separation and properties of a “Neutral” hexosaminidase from embryonic chicken brain

• 1.1. A “neutral” hexosaminidase has been separated from other hexosaminidase forms (I and II) by DEAE-cellulose chromatography and characterized in embryonic (16-days old) and 1-day old chicken brains.
• 2.2. Its properties differ from those of the forms I and II. It has optimum activity at about pH 6.0 and can be eluted from DEAE-cellulose with 0.25 M KCl only.
• 3.3. It has no N-acetylgalactosaminidase activity and cannot be successfully detected after isoelectric focusing since it is very acidic and completely unstable below pH 5.0.
• 4.4. “Neutral” hexosaminidase is heat-stable at pH 6.0 and is inhibited by chloride.
• 5.5. These properties, very different from those of forms I and II, suggest that this “neutral” form of hexosaminidase would be very similar to known hexosaminidase C separated from other materials.
• 6.6. We have found no significant differences for the above-mentioned three forms in chick embryos (16-days old) in comparison with those from 1-day old chicken.

     

Enzyme activities and level of SH groups in breast carcinomas

• 1.1. The carcinoma showed higher enzyme activities than the normal mammary tissue.
• 2.2. The ratios of glutamate dehydrogenase, glutathione reductase and catalase to lactate dehydrogenase were lower in carcinomas than in normal tissues. Similarly, the ratios of glutamate dehydrogenase, glutathione reductase and catalase to glucose-6-phosphate dehydrogenase were also significantly lower in carcinomas.
• 3.3. There were no significant differences in enzyme activities between stages I and II of disease, however in the metastatic tissues, there were significant differences between stages I and II.
• 4.4. SH groups were higher in the tissues of cancer patients than in normal tissues. The levels of thiols groups were higher in carcinomas at stage III of disease.

     

The influence of optic nerve section on blood metabolite levels in Carcinus maenas (Crustacea: Brachyura)

• 1.1. Blood metabolite levels were assayed in Carcinus maenas as an indicator of the functioning of the hyperglycemic hormone, HGH, secreted by the crab's eyestalk neuroendocrine tissue.
• 2.2. Bilateral eyestalk ablation eventually resulted in a hypoglycemic response after 2–3 days.
• 3.3. Bilateral optic nerve section produced a significant, long-term hypoglycemic response suggesting that release of HGH from the eyestalk sinus gland is controlled, via a promotive neural pathway, by the CNS and probably by the cerebral ganglia.
• 4.4. Injection of eyestalk extract into operated crabs consistently produced significant, short-term hyperglycemia.

     

The stimulation of yeast mitochondrial protein synthesis by low molecular weight cytoplasmic factors: Requirement for intact mitochondria and lack of effect by folate derivatives

• 1.1. Protein synthesis by GTP -supplemented yeast mitochondria is stimulated by a fraction of molecular weight less than 2,000 isolated from yeast high-speed supernatant (S-150).
• 2.2. The low molecular weight fraction works independently of the respiratory chain as the stimulation effect is not cyanide-sensitive.
• 3.3. Stimulation of mitochondrial protein synthesis by cytoplasmic factors is dependent upon the method of mitochondrial isolation.
• 4.4. The low molecular weight stimulatory factor(s) are not reduced folate derivatives which supply formyl groups required for initiation of mitochondrial protein synthesis.

     

How the atmosphere and the presence of substrate affect the photo and non-photoinactivation of heme enzymes by uroporphyrin I

• 1.1. The effect of URO I on the activity of ALA-D, PBGase, deaminase and URO-D, both in aerobiosis and anaerobiosis, was studied.
• 2.2. Photoinactivation of the enzymes was much lower in an anaerobic than in an aerobic atmosphere.
• 3.3. Dark inactivation in the absence of oxygen was lower than its presence.
• 4.4. Preincubation in the presence of ALA or PBG protected the enzymic activity of ALA-D, PBGase and deaminase against URO I-inactivation both under u.v. light and in the dark.
• 5.5. Photoinactivating action of URO I would be mediated by reactive oxygen species generated by the excited porphyrin after its absorption of light. Dark inactivation, in aerobiosis, can also be partly mediated by amino acid oxidation, although to a lesser extent than that observed under u.v. light.

     

Superposition and scattering of visual fields in a compound,double eye—II. Stimulation sequences for different distances in a stomatopod from a bright habitat

• 1.1. The inputs deriving from a point light moving in front of a column of ommatidia are plotted by a computer.
• 2.2. Overlap of visual fields causes one main, central maximum surrounded by smaller maxima intercalated by minima.
• 3.3. With increasing distance of the point from the eye the central maximum increases.
• 4.4. Ommatidia in each half of the eye are stimulated sequentially in two groups. Stimulation sequences are parallel between the two halves of the eye.
• 5.5. We postulate an integrative mechanism for processing the succession of simultaneous inputs and hypothesize that the animal derives information about speed and distance from that mechanism.

     

Flight-induced increase in circulating levels of melatonin in the homing pigeon

• 1.1. Homing pigeons, receiving regular flight-training for participation in racing competitions, were flown from their usual release site, 48 km away from “home”.
• 2.2. On their return “home” within 60–80 min, blood samples for the measurement of melatonin were taken within 1–3 min of arrival.
• 3.3. Post-flight circulating levels of melatonin were found to be about 82% higher than those of the resting control pigeons without any change in plasma osmolality.
• 4.4. This daytime increase in circulating levels of melatonin suggests that melatonin, by virtue of its known hypothermic effect of facilitating peripheral heat dissipation, could prevent excessive flight-induced hyperthermia.
• 5.5. It is also suggested that the flight-induced increase in plasma levels of melatonin is consistent with the known analgesic and metabolic effects of the hormone.

     

Oxidation of methionine residues in equine growth hormone by chloramine-T

• 1.1. Reactivity of methionine residues towards Chloramine-T was studied in the equine growth hormone.
• 2.2. With a 20.0-fold molar excess of reagent over methionine, full oxidation of the four residues of the protein is achieved.
• 3.3. Methionine 4 is the most reactive group, followed by methionines 72 and 178—methionine 123 being the less reactive residue.
• 4.4. As judged by circular dichroism spectra and binding assays, protein conformation and binding capacity to specific receptors remains unchanged even after full oxidation of all four methionine residues.
• 5.5. Results agree with data previously obtained with bovine growth hormone.

     

NNAlign_MA; MHC Peptidome Deconvolution for Accurate MHC Binding Motif Characterization and Improved T-cell Epitope Predictions

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Highlights

• •NNAlign_MA enables full deconvolution of single MHC specificities from MS assays.
• •NNAlign_MA expands MHC allelic coverage, improving identification of T-cell epitopes.
• •NNAlign_MA was benchmarked on MHC classes I and II, outperforming current methods.
• •NNAlign_MA offers a universal solution to analyze and exploit MHC peptidomics data.