Low metabolic rate in a nocturnal desert lizard,an arbylus switaki murphy (Sauria: Gekkonidae)

• 1.1. Metabolic rates were measured in two xeric-adapted gekkonid lizards, Anarbylus switaki sind Coleonyx variegatus.
• 2.2. Standard metabolic rates (SMR) were 0.074 ml O₂/g hr in A. switaki and were 70% of the value predicted on the basis of mass from regression equations. The SMR of 0.146ml O₂/ghr in C. variegatus is similar to the predicted value for a lizard of this mass.
• 3.3. During intense activity, metabolic rates of 0.378 and 0.804ml O₂/g hr were measured in A. switaki and C. variegatus, respectively.
• 4.4. Various theories to explain reduced SMR in lizards are discussed, and it is concluded that none is entirely satisfactory, and caution should be exercised in interpreting the adaptive significance of reduced SMR.

     

Changes in the activities of lysosomal enzymes in the fat body and midgut of two lepidopteran insects (Mamestra brassicae and Pieris brassicae) during metamorphosis

• 1.1. The activities of three lysosomal enzymes (acid phosphatase, β-galactosidase, catepsin D) was observed during metamorphosis in the fat body and midgut cells of two insects (Mamestra brassicae and Pieris brassicae).
• 2.2. The activities increased slightly during the feeding period and showed a sharp rise at the beginning of the wandering period.
• 3.3. Subsequently, a decrease was observed during the pre-pupal stage and pupation.
• 4.4. The activities increased again 2 days after the larval-pupal moult.
• 5.5. We suggest that an inhibitory mechanism works in the studied cells before pupation to protect the stored proteins from the degradation until the beginning of differentiation of imaginai cells in the pupal stage.

     

A comparative study on the biological properties of venoms from juvenile and adult common tiger snake (Notechis scutatus) venoms

• 1.1. The biological properties of venoms from juvenile and adult common tiger snakes (Notechis scutatus) were compared.
• 2.2. The lethality, procoagulant activity and enzymatic activities of the juvenile venom were not substantially different from those of the adult venom.
• 3.3. Electrophoretic studies, however, indicated some minor differences in the protein composition of the juvenile and adult venoms.

     

Mixed function oxidase activity in the harbour seal (Phoca vitulina) from sable is., N.S.

• 1.1. One adult male, eight pups (including two full term foetuses) and nine adult female harbour seals (Phoca vitulina) were analysed for indices of mixed function oxidase (MFO) activity.
• 2.2. MFO activity was present in liver samples, but was at or below detection limits in samples of kidney, lung and pancreas.
• 3.3. Hepatic ethoxyresorufin O-de-ethylase and benzo[a]pyrene hydroxylase activities were similar to those reported in other seals and in other mammals.
• 4.4. Cytochromes P-450 and b₅ concentrations were slightly lower than those observed in other mammals.
• 5.5. MFO activities in newborn pups and foetuses were significantly lower than those in adult females.
• 6.6. No qualitative differences in cytochrome P-450 isozyme distribution between foetal and adult samples could be discerned by electrophoresis.

     

S-Adenosyl-l-methionine decarboxylase activities in Mytilus edulis

• 1.1. The activities of S-adenosylmethionine decarboxylase (EC 4.1.1.50) were measured in cell extracts of mantle, hepatopancreas and foot from Mytilus edulis.
• 2.2. The apparent molecular weights of the enzymes estimated by gel filtration chromatography were 65,000 ± 10,000.
• 3.3. The enzymes do not require bivalent cations for catalysis and show optimum pH between 7.0–8.0 in phosphate buffer.
• 4.4. The hepatopancreas enzyme shows different behavior to the other two enzymes against temperature and its activity is strongly inhibited by NH₄⁺.
• 5.5. The apparent K_ms for S-adenosylmethionine were found to be 300, 200 and 250 μM for the hepatopancreas, mantle and foot enzymes, respectively.

     

Trypanosoma cruzi and Trypanosoma rangeli: Glutamate dehydrogenases and proteolytic activities

• 1.1. Trypanosoma (Herpetosoma) rangeli contains proteolytic activity with azocasein, casein and BAPA as substrates, and aminopeptidase activity with Arg-BNA as substrate. The respective pH optima were 5.5, 7.0, 8.5 and 7.0.
• 2.2. The effect of the protease inhibitors PMSF, TLCK and trasylol was studied. 0.5 mM TLCK caused considerable inhibition of all these activities, whereas 1 mM PMSF was much less effective. Trasylol (0.14 mg/ml) inhibited the activities with azocasein and Arg-BNA as substrates.
• 3.3. Trypanosoma (Schizotrypanum) cruzi contains very similar proteolytic activities, with some slight differences in pH optima and in response to inhibitors. Thus Trasylol was not effective on any activity, and the activity on Arg-BNA was little sensitive to TLCK.
• 4.4. The levels of these enzymes, and also of the NAD- and NADP-linked glutamate dehydrogenases, were studied in six stocks of T. (Sch.) cruzi and three stocks of T. (H.) rangeli. There was no significant difference in the NAD-gluDH, nor in the proteolytic activity with BAPA. On the other hand, the other enzymes tested presented differences which ranged from about 3-fold for the aminopeptidase to nearly 100-fold for the NADP-gluDH. The electrophoretic behaviour of the latter was identical in all the stocks of both species, thus showing that the difference was only quantitative.
• 5.5. The three stocks of T. (H.) rangeli were more similar to some T. (Sch.) cruzi stocks (Tul 2) than the latter were to each other, thus emphasizing at a biochemical level the similarities between these two species.

     

Comparative study of proteolytic enzymes in the digestive tracts of the european sea bass and hybrid striped bass reared in freshwater

• 1.1. A comparative study of the proteolytic activity in four different sections of the digestive tracts of the European sea bass (Dicentrarchus labrax) and hybrid striped bass (Morone chrysops × M. saxatilis) reared in freshwater revealed minor differences between these fish.
• 2.2. Tryptic activity plays a major role in the proteolytic process in both fish.
• 3.3. The activity of seven intestinal proteolytic enzymes was detected utilizing a combination of specific substrates and inhibitors.
• 4.4. High levels of proteolytic activity were detected in both the proximal and distal sections of the fish intestine at a high pH range (9–10).
• 5.5. In situ monitoring of pH levels revealed a lower pH level in the intestinal proximal section of hybrid striped bass compared with the distal section.
• 6.6. In contrast, higher pH levels were detected at the proximal compared with the distal sections of D. labrax intestine.

     

NAD(P)H dehydrogenase from rabbit and rat liver: Purification and some properties

• 1.1. NAD(P)H dehydrogenase from rabbit liver was purified to electrophoretic homogeneity using a procedure also found applicable for the rat liver enzyme.
• 2.2. Rabbit and rat liver enzymes showed different behaviour in isoelectric focusing and different K_m values and turnover numbers.
• 3.3. Both enzymes were inhibited to similar extents by warfarin.
• 4.4. The rabbit enzyme is composed of two subunits of mol. wt 27,000 and contained 1 FAD group per subunit.
• 5.5. Some absorption and circular dichroism properties of the rat enzyme are shown.

     

Thermal properties for digestive enzymes of a sub-antarctic beetle,hydromedion sparsutum (coleoptera,perimylopidae) compared to those in two thermophilic insects

• 1.1. Proteolytic, lipolytic, amylolytic and cellulolytic activities were studied in adults of the phytophagous beetle, Hydromedion sparsutum, indigenous to the sub-Antarctic island of South Georgia.
• 2.2. Gastric enzyme activities were measured at experimental temperatures of 5–40°C and results were compared with those obtained from two thermophilic insects, Gryllus bimaculatus and Tenebrio molitor.
• 3.3. Protease and lipase activities in Hydromedion were 10–15 times lower than in Gryllus and Tenebrio.
• 4.4. In the temperature range of 5–15°C, α-amylase activity from Hydromedion was only slightly lower than that from Gryllus.
• 5.5. Hydromedion gut homogenates exhibited a distinct cellulolytic activity, even at a low temperature of 5°C.
• 6.6. Cellulolytic activity in the digestive tract of Hydromedion was confirmed by the evolution of ¹⁴CO₂ after consumption of labelled cellulose.
• 7.7. The thermal properties of digestive enzymes agree well with the role of Hydromedion as primary decomposer in its ecosystem.

     

Purification and some properties of apurinic/apyrimidinic dna endonucleases in rat liver

• 1.1. Three kinds of apurinic/apyrimidinic (AP) DNA endonucleases, APcI, APcII, APcIII were purified from rat liver chromatin.
• 2.2. Molecular weights of APcI, APcII and APcIII were 30,000, 42,000 and 13,000 Da, which have isoelectric points of 7.2, 6.3 and 6.2, respectively.
• 3.3. Mg²⁺ was essential for the activities of these 3 enzymes, and sulfhydryl compounds (βercaptoethanol) had a stimulatory effect on the enzyme activities while N-ethylmaleimide and HgCl₂ inhibited the enzyme activity.
• 4.4. K_m values of APcI, APcII and APcIII for AP site of DNA were 0.53, 0.27 and 0.36 μM, respectively, and AMP was the most potent inhibitor to these three enzymes among nucleotides tested.

     

Content and synthesis of several abundant glycolytic enzymes in skeletal muscles of normal and dystrophic mice

• 1.1. In both 2- and 3-month-old 129 ReJ mice, the catalytic activity levels of three enzymes involved in glycogen breakdown (phosphorylase, enolase, and aldolase) were found to be 35–50% lower in hind limb muscles of dystrophic mice as compared with normal mice.
• 2.2. The reduced activities of these enzymes in the diseased tissue was directly due to corresponcling reductions in the number of enzyme molecules rather than being due to inactivation of the enzymes in the dystrophic muscle.
• 3.3. Results of short term double isotope incorporation experiments conducted with muscle expiants in vitro suggested that the rates of synthesis of these enzymes, and of most other abundant cytosolic proteins, relative to each other, were similar in hind limb muscles of normal and dystrophic mice.
• 4.4. The present work on murine muscular dystrophy is discussed in terms of our previous studies into the influence of avian muscular dystrophy on the content and synthesis of abundant glycolytic enzymes in chicken skeletal muscles.

     

Hematology and blood chemistry of the marsh harrier (Circus aeruginosus)

• 1.1. This study deals with the hematological and blood chemistry of 13 adult marsh harriers (Circus aeruginosus).
• 2.2. No significant differences were observed between male and female groups in any of the parameters.
• 3.3. The value of white blood cells was 14,677/mm³ heterophils and lymphocytes, these being the most abundant cellular type (81.42 and 12%, respectively).
• 4.4. Urea and uric acid are present in approximately similar proportions, though birds are said to be uricotelic.
• 5.5. The cholesterol concentration values determined in our study, are higher than those reported in most other birds.

     

Pyrimidine degradation in tomato cell suspension cultures and in Euglena gracilis—localization of enzymes

• 1.1. Subcellular location of dihydropyrimidinase and NCβA-amidohydrolase2 was studied in a cell suspension culture of tomato (Lycopersicon esculentum cv. Lukullus) and in Euglena gracilis.
• 2.2. By differential centrifugation, crude extracts were separated into ten fractions. Activities of both enzymes were found mainly in cytosolic fractions marked by EDH (tomato) and glu-6-P-DH (E. gracilis).
• 3.3. A cytosolic location was also found by a 20–60% and a 17.5–30% sucrose density gradients.
• 4.4. Using mitochondrial marker enzymes such as fumarase, SDH, CS and MDH, a mitochondrial occurrence of both enzymes or their release from mitochondria can be excluded by sucrose gradient centrifugations. This can also be achieved using purified mitochondria prepared from tomato cells by two subsequent sucrose gradients.
• 5.5. A possible vacuolar location of dihydropyrimidinase and NCβA-amidohydrolase was excluded by comparing their activities in isolated protoplasts and purified vacuoles which were characterized by their marker enzyme α-mannosidase.
• 6.6. A nuclear location of both enzymes and/or their release from the nucleus during procedures used cannot be excluded.
• 7.7. The results are discussed in relation to subcellular location to other pyrimidine-metabolizing enzymes in plant cells.

     

Digestive protease,lipase and amylase activities in stage i larvae of the american lobster,Homarus americanus

• 1.1. Digestive protease, lipase, and amylase of Stage I larvae of the American lobster Homarus americanus are characterized.
• 2.2. A sensitive method for detection of crustacean lipase was developed using an latroscan which combines thin-layer chromatography and flame ionization detection to quantify free fatty acids generated by lipase digestion.
• 3.3. pH optima of the three enzymes occurred at or near the pH of gastric fluid.
• 4.4. A time course study demonstrated slight increases in protease and amylase activities during the first larval stage, regardless of whether the lobsters were fed or not, whereas lipase activity was constant.

     

Solubilization and characterization of functionally coupled Escherichia coli heat-stable toxin receptors and particulate guanylate cyclase associated with the cytoskeleton compartment of intestinal membranes

• 1.1. Particulate guanylate cyclase and receptors for E. coli heat-stable enterotoxin were solubilized from the rat intestinal cytoskeletal compartment using Lubrol-PX and KC1.
• 2.2. Thirty to forty percent of the ST receptor and guanylate cyclase activities were extracted from the lipid layer with Lubrol-PX alone.
• 3.2. Seventy percent of the remaining activities were solubilized from the cytoskeleton with Lubrol-PX and KCl.
• 4.3. Guanylate cyclase solubilized from either compartment exhibited similar reaction kinetics.
• 5.4. Both high- and low-affinity classes of ST receptors were solubilized from the lipid and cytoskeleton compartments.
• 6.5. In the presence of ATPγS, ST selectively activated the guanylate cyclase solubilized from the cytoskeleton compared to that solubilized from the lipid bilayer.
• 7.6. Crosslinking experiments demonstrated a preferential solubilization of the 130 kDa receptor subunit from the cytoskeleton and the 56 kDa subunit from the lipid bilayer.
• 8.7. Development of a procedure to solubilize ST receptors and guanylate cyclase from the intestinal membrane cytoskeleton will permit purification and further detailed studies of the coupling of these activities.

     

The haemocytes and the activities of leucine aminopeptidase and alkaline phosphatase during development of Ceratitis capitata: Specific secretion of a leucine aminopeptidase isozyme

• 1.1. The types of haemocytes during larval development were studied.
• 2.2. The developmental profile of leucine aminopeptidase and alkaline phosphatase was studied. The maximum LAP activity was found to be in early larval development, while the maximum alkaline phosphatase during the white pupal stage.
• 3.3. These activities were compared with those determined in cell-free haemolymph.
• 4.4. Both hydrolytic enzymes have been found histochemically in the prohaemocytes and in the plasmatocytes.
• 5.5. In cultured haemocytes experiments it was found that 64% of the total LAP activity was secreted into the incubation medium, while electrophoretic analysis of released LAP activity demonstrated that only LAP A isozyme was secreted.
• 6.6. Based on the above results we suggest that both hydrolytic enzymes are functionally important throughout larval development.

     

Compensations for temperature in the activities of digestive enzymes of Periplan eta americana (L.)

• 1.1. Differential thermal acclimatory responses of maximal catalytic rates (V_max) of digestive enzymes have been measured in both sexes of Periplaneta americana adapted to 16 and 32°C.
• 2.2. Salivary amylase of females and gastric protease of males exhibit “translational” acclimation, the former showing a “complete” but the latter only a “partial” compensation. The value of Q₁₀ is not altered in the adaptive response.
• 3.3. An alteration of the thermal coefficient is evidenced by the “translational-cum-rotational” compensation of gastric amylolytic activity, with significant warm acclimation but no cold acclimation in both sexes.
• 4.4. Gastric protease of female cockroaches and gastric lipase of both sexes are characterized by the lack of an adaptive compensation to temperature, while salivary amylase of male appears to manifest an “inverse” acclimation.
• 5.5. Sexual dimorphism in the levels of the activities and in the patterns of thermal acclimation of the digestive enzymes is indicated.

     

Glycolytic enzymes of fowl and turkey spermatozoa

• 1.1. It was confirmed that, under anaerobic conditions, fowl spermatozoa formed lactate from glucose thirteen times faster than turkey spermatozoa.
• 2.2. The profiles of glycolytic enzyme activities were similar for spermatozoa from both species; however fowl spermatozoal activities were generally 2- to 4-fold higher.
• 3.3. Exceptions were glycerophosphate mutase and lactate dehydrogenase activities which were respectively 9.5 and 41 times greater in fowl spermatozoa.
• 4.4. In both species, spermatozoal glyceraldehyde-3-phosphate dehydrogenase had the lowest activity of the glycolytic enzymes.

     

Intermediary metabolism of normal and tumorous tissue of Xiphophorus (Teleostei: Poeciliidae)

• 1.1. The Xiphophorus melanoma system is one of the few well established and genetically well understood in vivo models in experimental carcinogenesis. However, data describing features of intermediary metabolism of the genetically caused melanoma or the different inducible neoplasia, as well as that of the different transformed cell lines of Xiphophorus, are still lacking. For this reason we initiated a comparative study of enolase-, pyruvate kinase-, lactate dehydrogenase- and malate dehydrogenase-activities and pyruvate and lactate levels in transformed as well as normal tissues of Xiphophorus.
• 2.2. We observed tissue specific and age dependent activities of the different enzymes and substrate levels.
• 3.3. Enzyme activities and substrate levels from all tumors analyzed differ from that of any normal tissue. They are dependent on the tumor sections analyzed, the histiotype and the etiology of the tumors.
• 4.4. Analysis of enzyme activities from different in vitro cultured fish cell lines and the human Hela cell line revealed dependency of the intermediary metabolism on oxygen supply, on the proliferative state of the cells and on the cell types.
• 5.5. We could not find a correlation between our data and the expression of the c-src gene of Xiphophorus and no genotype-dependent changes in enzyme activities were detected.

     

Digestive proteases in the midgut gland of the atlantic blue crab,Callinectes sapidus

• 1.1. Digestive proteases from the midgut gland of male Atlantic blue crabs, Callinectes sapidus, were investigated. Tentative identities of proteolytic enzymes were determined with synthetic substrates and inhibitors.
• 2.2. Trypsin, chymotrypsin, carboxypeptidase A and B and leucine aminopeptidase activities were found and quantified.
• 3.3. Activity against Succinyl-(Ala)₃-nitroanalide was also found. This as yet unidentified enzyme has a mol. wt of about 26,000 and has elastolytic activity.