Transamination and transsulphuration of l-cysteine in ehrlich ascites tumor cells and mouse liver: The nonenzymatic reaction of l-cysteine with pyruvate

• 1.1. The activity of cysteine aminotransferase (CAT), 3-mercaptopyruvate sulfurtransferase (MPST) and rhodanese is much lower in Ehrlich ascites tumor cells (EATC) than in mouse liver.
• 2.2. Contrary to mouse liver homogenate, no synthesis of sulphane sulphur-containing compounds from L-cysteine is observed in EATC homogenate.
• 3.3. 2-Methyl-thiazolidine-2,4-dicarboxylic acid (CP), 2-methyl-thiazolidine-4-carboxylic acid (CA) and thiazolidine-4-carboxylic acid (CF) can be used as sources of low molecular-weight thiol compounds both in EATC and mouse liver homogenate.
• 4.4. Pyruvate formed from phosphoenolopyruvate (PEP) in EATC homogenates reacts with L-cysteine (l-CYS) to CP.

     

Correlation of acid phosphatase but not alkaline phosphatase activity with myelination in the developing mouse brain

• 1.1. Neonatal mice received subcutaneous injections of buffer, thiourea (TU) or propylthiouracil (PTU).
• 2.2. The PTU-treated mice were sacrificed on postnatal day 14 (P14) and the TU-treated mice on P28.
• 3.3. Brain weights of the TU- and PTU-treated mice were not significantly different from the controls.
• 4.4. Acid but not alkaline phosphatase activity in the braistem decreased after TU and PTU treatment.
• 5.5. Myelination as indicated by intensity of luxol fast blue staining was weaker in drug-treated animals.
• 6.6. The level of myelin marker enzyme, 2′,3′-cyclic nucleotide 3′-phosphohydrolase, was lower in the brainstem of PTU-treated animals.
• 7.7. The results suggest a correlation between acid phosphatase but not alkaline phosphatase activity with myelination in the developing mouse brain.

     

Phenoloxidase activity of acridid grasshoppers from the subfamilies melanoplinae and oedipodinae

• 1.1. Phenoloxidase activity and wound melanization was studied in five species of grasshoppers representing the subfamilies Melanoplinae and Oedipodinae.
• 2.2. Most of the phenoloxidase activity was detected in the plasma fraction of grasshopper whole-body homogenates and supernatant fractions of the hemolymph. The species representing the Oedipodinae had 20–50% higher percentage of the total phenoloxidase activity associated with particulate matter from a whole-body homogenate when compared to the Melanoplinae.
• 3.3. Phenoloxidase activity could not be detected in sclerotized cuticle of adult grasshoppers.
• 4.4. The phenoloxidase existed as a zymogen which could be activated by chymotrypsin and inhibited by KCN and NaCN while EDTA showed no effect. It had optimum activity at 37°C and pH 7.3.
• 5.5. These findings are discussed in relation to wound repair and immune responses to infection in grasshopper species.

     

γ-Glutamyltranspeptidase in echinoderm eggs and larvae: fertilization-dependent and developmentally-induced changes in specific activity

• 1.1. γ-Glutamyltranspeptidase is present in echinoderm eggs and larvae: in homogenates the level of activity is comparable to that of rat cerebral cortex.
• 2.2. In eggs of Lytechinus pictus, fertilization induces an early rapid and sustained (5 min–6 hr) 37% increase in the activity of γ-glutamyltranspeptidase in homogenate fractions.
• 3.3. Relative to these homogenate levels, the specific activity of γ-glutamyltranspeptidase are ≈60% lower in 40,000 g supernatant fractions and 2.7-fold higher in 40,000 g particulate fractions in both unfertilized and 15 min post-fertilized Lytechinus pictus eggs.
• 4.4. The subcellular distribution of γ-glutamyltranspeptidase is the same in both unfertilized and 15-min post-fertilized Lytechinus pictus eggs: 78% in 40,000 g particulate fractions, 22% in 40,000 g soluble fractions.
• 5.5. In both unfertilized and 15 min post-fertilized eggs of Lytechinus pictus the enzyme responds to heat (50 vs 37°C) by activation in a similar manner: 1.72- and 1.68-fold homogenates; 2.6- and 3.0-fold in supernatants; 1.97- and 1.90-fold in particulate fractions.
• 6.6. In homogenates of Pisaster ochraceous larvae, γ-glutamyltranspeptidase activity increases steadily during the course of larval development: relative to the low activity at day 5, activities exhibit an increase of 1.2-, 2.0-, 3.1- and 5.4-fold at days 10, 16, 22 and 28, respectively.

     

In vitro-studies on the anaerobic formation of ethanol by the larvae of Chironomus thummi thummi (Diptera)

• 1.1. The anaerobic formation of ethanol by the larvae of Chironomus thummi thummi was investigated in homogenates and isolated mitochondria.
• 2.2. It was found that homogenates transform fructose-1,6-bisphosphate into ethanol and acetate. The accumulation of ethanol decreases substantially and the formation of acetate almost ceases when arsenite, an inhibitor of pyruvate dehydrogenase, is present in the incubation medium.
• 3.3. The cytosolic fraction of the homogenate was shown to degrade fructose-1,6-bisphosphate to pyruvate only. No ethanol could be detected, although there is high activity of alcohol dehydrogenase in the cytosol.
• 4.4. Isolated mitochondria produce large quantities of ethanol from pyruvate during anoxia. This ethanol production was shown to depend on the presence of NADH. It is deduced that this cosubstrate originates from intramitochondrial formation of acetate from pyruvate, which was always found to accumulate alongside ethanol.

     

Oxidative metabolism of the inner and outer ventricular layers of carp heart (Cyprinus carpio L.)

• 1.1. The biochemical characteristics of homogenates and mitochondria isolated from the outer and inner layers of the ventricular myocardium of carp were studied.
• 2.2. The homogenate prepared from the inner layer exhibited higher activity of cytochrome oxidase than that from the outer layer. No difference was found in the activity of cytochrome oxidase between mitochondria from the inner and outer layers. Difference spectra of cytochromes also showed that their content in mitochondria of both layers is similar and that the higher oxidative capacity of the spongious layer is due to a higher content of mitochondria.
• 3.3. In comparison with rat heart a higher content of cyt aa₃ and a lower content of Cyt b and cyt cc₁ were found in carp heart mitochondria.
• 4.4. In comparison with rat heart, carp heart mitochondrial enzymes were more sensitive to freezing-thawing and to detergent action.

     

Role of antiproteolytic heparin-binding serum protein(s) in modulating the levels of sialyl- and galactosyltransferase activity released during the incubation of rat jejunal slices

• 1.1. Sialyltransferase released into the medium during the incubation of rat jejunal slices in serum-free buffer, was susceptible to proteolytic degradation. Heat inactivated horse serum or its antiproteolytic heparin-binding fraction was found to be necessary in determining the activity of sialyltransferase released (Nadkarni et al., 1991).
• 2.2. In the present study, we have shown that heat inactivated rat serum (HRS) or its antiproteolytic heparin-binding fraction (HBF) had a role in determining the sialyltransferase activity released during jejunal slice incubations.
• 3.3. Galactosyltransferase was also released during incubations, but was not proteolytically degraded and the presence of HRS or HBF in incubations did not alter the levels of galactosyltransferase activity released.
• 4.4. Trypsin activity in serum-free incubation medium was higher compared to medium containing HRS.
• 5.5. Addition of serum-free medium obtained from 4 hr incubations of the jejunal slices, to medium obtained from parallel incubations done in the presence of HRS, caused inhibition of sialyl- but not galactosyltransferase activity.
• 6.6. In jejunal homogenates stored at −20°C, sialyltransferase activity was decreased during 0–45 days of storage, whereas galactosyltransferase activity remained fairly stable for upto 56 days.
• 7.7. Inclusion of HRS or HBF in homogenates resulted in higher sialyl- but not galactosyltransferase activity compared to serum-free homogenate samples.
• 8.8. The results suggest that HRS or its antiproteolytic heparin-binding proteins have a role in determining the sialyltransferase activity released from the jejunal slices. In contrast galactosyltransferase released was not susceptible to proteolysis, and HRS or HBF was not required to express its activity.

     

Purification and characterization of monkey albumin and proalbumin

• 1.1. Albumin purified from rhesus monkey (MSA) shows immunological cross-reactivity with human serum albumin (HSA) by RIA.
• 2.2. The amino-terminal sequence of MSA shows a high degree of homology to HSA.
• 3.3. Thirty minutes after injection of radioactive leucine directly into the portal vein, albumin was purified chemically from the liver, kidneys and serum.
• 4.4. At this time, 15% of the label was incorporated into liver homogenate protein.
• 5.5. A highly labelled immunoreactive albumin form was purified from liver to constant specific radioactivity and separated from tissue and serum albumin.
• 6.6. The specific radioactivity of this proalbumin was 36-times higher than the specific radioactivity of albumin in liver tissue.
• 7.7. These similarities to HSA suggest that this non human primate species can serve as a useful model of human albumin synthesis in vivo.

     

Evidence of an egg-laying factor in the prostatic secretions of Helix aspersa müller

• 1.1. A high percentage (53%) of isolated snails injected with prostate gland homogenates lay eggs.
• 2.2. These egg masses consist of a few eggs which contain many nonviable oocytes.
• 3.3. Preliminary experiments suggest that an egg-laying factor may be present in prostatic secretions.
• 4.4. Snails bred in isolation from hatching, whether injected or not, occasionally lay viable eggs.
• 5.5. This observation shows that self-fertilization or parthenogenesis is, in fact, possible in Helix aspersa Müller.

     

A comparison of tissue lipoprotein lipase activities determined in either fresh or defatted tissue preparations

• 1.1. Lipoprotein lipase activities were determined in either fresh aqueous homogenates or homogenates of acetone-diethyl ether dried powders of adipose tissue, heart, skeletal muscle and lung tissue taken from both fed and 24 hr starved rats.
• 2.2. The total tissue enzyme activities detectable in powder preparations were considerably higher than those of fresh preparations in all the tissue except lung.
• 3.3. The identity of the enzyme activity was more clearly demonstrable with homogenates of solvent-dried powders.
• 4.4. The use of both types of preparation in an experiment where rats were injected with either saline or colchicine further demonstrated the advantages of the acetone-diethyl ether-dried tissue preparation in total tissue lipoprotein lipase activity determinations.

     

Immunochemical and immunohistochemical determination of ubiquitin in molluscan (Mytilus edulis) smooth muscle

• 1.1. Immunochemical and immunohistochemical distribution of ubiquitin in the anterior byssus retractor muscle (ABRM) of Mytilus edulis was investigated.
• 2.2. In immunostaining, specific ubiquitin immunoreactivity was observed in the cross-sectioned ABRM, and was uniformly localized in this section.
• 3.3. The amount of free ubiquitin in the ABRM homogenate was 130 ± 4.6 ng/mg protein by western blot analysis, and ubiquitin conjugates were found at about 25, 29 and 200–230 kDa.
• 4.4. These findings were similar to those obtained in the skeletal muscle of rat.

     

Purification and partial characterization of an AMP deaminase from the marine invertebrate Palaemon serratus

• 1.1. AMP deaminase from Palaemon serratus tail muscle was partially purified by chromatography on cellulose phosphate.
• 2.2. Muscle homogenates expressed very low enzyme activities and the presence of ATP was necessary to detect AMP deaminase. The specific activity and substrate affinity of the purified enzyme were also very low.
• 3.3. The purified prawn muscle AMP deaminase was contaminated by contractile proteins, one of the major contaminants being actin.
• 4.4. The enzyme displayed a very high affinity for actomyosin which was only partially abolished by pyrophosphate.

     

Main kinetic characteristics of acetylcholinesterase from brain of Hypostomus punctatus,a Brazilian bentonic fish (cascudo)

• 1.1. A potentiometric method for the assay of cholinesterase has been proposed and compared with a colorimetric assay.
• 2.2. Main kinetic parameters of cholinesterase from Hypostomus punctatus brain were determined indicating that true acetylcholinesterase is by far the predominant enzyme in the brain of this fish.
• 3.3. We have compared our data with published results described from other fish species.
• 4.4. The enzyme inhibition achieved after 3 hr incubation of brain homogenates with ethyl-parathion have indicated that this enzyme shows a characteristic organophosphorous sensitive behavior.

     

Level of ascorbic acid in adrenal glands of laboratory mice bred in various population densities

• 1.1. Laboratory mice were bred in groups of 20, 60 and 100 mice per cage. Male to female ratio was 1:1.
• 2.2. The experiment was carried out in autumn-winter and winter-spring.
• 3.3. Levels of ascorbic acid were determinated in homogenates of adrenal glands after 10 weeks of breeding.
• 4.4. Three- and five-fold increase of number of mice in the same area caused the decrease of ascorbic acid level in adrenal glands of active males, non-pregnant and nursing females. In pregnant females this correlation was not observed.
• 5.5. Decrease of ascorbic acid level due to increase of adrenal glands' weight was also observed.

     

The characterization of the linoleic acid desaturation and elongation system in ovine placental tissue

• 1.1. The desaturation and elongation of linoleic acid has been studied in homogenates and in subfractions of ovine placental tissue.
• 2.2. The reaction was characterized in terms of pH and temperature optima, time course and protein concentration.
• 3.3. Activity was found to be confined to the 11,000g supernatant fraction of the tissue and the results suggest that the enzymes are membrane bound.
• 4.4. The cytosolic fraction and ATP were required for full activity and the reaction was inhibited by cyanide.
• 5.5. The properties of the reaction are compared with those of other desaturation systems and their implications with regard to possible reaction mechanisms are discussed.

     

12-O-tetradecanoylphorbol-13-acetate enhances glycolysis in rat thymocytes

• 1.1. The potent tumor promoter 12-O-tetradecanoylphorbol-13-acetate (TPA) induced a rapid increase in glycolysis in rat thymocytes.
• 2.2. The increase in the glycolytic flux was also reflected by elevated fructose 1,6-diphosphate levels.
• 3.3. TPA treatment did not result in an increase of hexokinase, phosphofructokinase or pyruvate kinase when measured in cell homogenates.
• 4.4. It is suggested that the early increase in glycolysis in TPA treated lymphocytes may result from TPA-mediated increase in glucose transport.

     

Temporal Proteomic Analysis of Pancreatic β-Cells in Response to Lipotoxicity and Glucolipotoxicity

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Highlights

• •Temporal proteome profiling of lipotoxicity and glucolipotoxicity in β-cells
• •Palmitate induced cholesterol metabolism earlier than fatty acid metabolism
• •Setd8 promotes palmitate + glucose-stimulated INS-1 cell proliferation
• •PA induced apoptosis partially via upregulation of Rhob in INS-1 cells

     

Alteration of the protein composition of bothrops jararaca venom and venom gland by isoproterenol treatment

• 1.1. The protein composition of Bothrops jararaca venom and venom gland was analyzed through SDS-PAGE, after isoproterenol (IPR) treatment.
• 2.2. Some proteins (47, 48, 57 and 72 kDa) were detected in the gland homogenate from the control but not from the IPR-treated samples.
• 3.3. Three proteins (26.5, 44.5 and 53 kDa) were detected in the venom gland from IPR-treated snakes but not from the venom gland from the control.
• 4.4. In the venom samples proteins of 41 and 74 kDa were detected only in the IPR treated samples, while proteins of 17 and 28 kDa were detected only in the control.
• 5.5. The biological activity of the venom did not change with IPR treatment.

     

The isolation of a plasma membrane-rich fraction from the skeletal muscle of two species of marine crab,Carcinus maenas and Cancer pagurus

• 1.1. A rapid method for the isolation of a plasma membrane-rich fraction from crab leg muscle, with high purity and yield recovery was developed.
• 2.2. The method is based on sodium iodide extraction of the crude homogenate, followed by centrifugation on Percoll self-creating gradient.
• 3.3. (Na⁺K⁺)ATPase and alkaline phosphodiesterase I were used as marker enzymes for the plasma membrane and revealed levels of purification of approximately 13-fold and yields recovery of the total activity in the crude muscle homogenate of approximately 18%, for both species of crab studied.

     

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