Ultrastructural distribution of peroxidase in thrombocytes of mammals and submammals

The localization and distribution of peroxidase (PPO) activity were studied ultracytochemically in thrombocytes from lampreys, carps, frogs, snakes, tortoises, rabbits, sheep, dogs, and monkeys. PPO activity was not detectable in the thrombocytes of lampreys, carps, frogs, and snakes. However, this enzyme activity was demonstrated in the nuclear envelope and endoplasmic reticulum of tortoise thrombocytes. Dog and monkey thrombocytes (blood platelets) exhibited PPO activity in the dense tubular system, but this enzyme activity was not detectable in rabbit and sheep thrombocytes. Our observations are interpreted to suggest that thrombocytes from animals lower than amphibia are peroxidase negative. Furthermore, it can be said that thrombocytes from animals higher than reptiles are generally positive, although there are exceptions. PPO activity was localized in the endoplasmic-reticulum system, but not in the cytoplasmic granules of thrombocytes common to submammals and mammals. In this study, we also compared the distribution of peroxidase activity in thrombocytes, neutrophils, and eosinophils and conclude that these are significant differences in the distribution of PPO and myeloperoxidase.     

Erythrocyte sorbitol dehydrogenase of selected non-mammalian vertebrates

Erythrocyte sorbitol dehydrogenase activity (EC 1.1.1.14) from selected non-mammalian vertebrates was studied showing great variability not related to their phylogenetical position. The Michaelis-Menten constant (Km) for sorbitol exhibited moderate low values in the studied animals. In snakes the Km for sorbitol was low with moderate activity of sorbitol dehydrogenase, suggesting that the enzyme could reach maximum activity with lower sorbitol concentration in comparison to other vertebrates. In the snakes the enzyme showed the same affinity for all the studied polyols, indicating that we are probably dealing with a very ancient enzyme, an unspecific enzyme.     

Comparative observations on AChE distribution in pancreas of some amphibians,reptiles and birds,with special reference to the islets of langerhans

Summary AChE activity in pancreas of some amphibians, reptiles and birds was investigated with light microscope using Karnovsky's technique.A nervous and an extranervous localization of the enzyme showing considerable qualitative and quantitative differences depending on the systematic group, could be discerned. Pancreatic peripheral cholinergic autonomic system comprises nerve fibers and perikarya. The latter seem to occur in newt and frogs as Cajal's interstitial cells (CIC) and are undoubtedly present in birds as CIC and as ganglionic cells. In lizard and snakes they were not present.The extranervous localization of AChE activity was observed in islet cells in frogs, lizards and snakes, also in the walls of blood vessels of all investigated poikilotherms.The findings are compared with results previously obtained in mammalian pancreas or in other organs. Some hypotheses on the physiological significance of enzyme presence in endocrine cells, as well as their belonging to APUD cell series are discussed.This work was supported by a fellowship of the Alexander von Humboldt-Stiftung, Bonn-Bad Godesberg and by the Deutsche Forschungsgemeinschaft (La 229-3). The author expresses his thanks to Prof. Dr. R. H. Lange for scientific advice.     

Proton acceptor properties of the blood plasma of a series of vertebrates

Comparative studies have been made on the kinetics of thermal denaturation of the blood plasma of various vertebrates (lampreys, teleosts, frogs, tortoises, pigeons, mice, rats, rabbits, cats, dogs, man) by measuring ionization equilibrium of protein solution at elevated temperature. It was demonstrated that during the initial stage of heat denaturation at 58 degrees the blood plasma of all the animals studied binds protons practically linearly. Among the animals studied, the highest protonoacceptor capacity exhibited the plasma of warm-blooded animals; it was lower in tortoises frogs and teleost fishes, being the lowest one in lampreys. Comparison of total electric charge of plasma proteins evaluated by potentiometric titration with data on thermal denturation of plasma revealed positive correlation between the charge and protonoacceptor properties of the plasma.     

Seasonal fluctuations of migratory activity of vertebrate nuclear hemocytes at different incubation temperatures

Agarose migration test has shown that nuclear erythrocytes of Cyprinus carpio, Rana ridibunda, and Gallus domesticus are capable for spontaneous locomotions. The migration of red blood cells from frogs is associated with formations of long pseudopodia, whereas that from carps and hens-with short protrusions. It has been shown that migratory activity of nuclear erythrocytes and leukocytes from Rana ridibunda and Gallus domesticus under effect of temperature in vitro had seasonal nature, while that from Cyprinus carpio did not depend on the year season. In frogs and hens the circadian oscillations of blood cell migration area are coupled with the organism functional activity, whereas no such association is present in carps.     

Does the Siberian chipmunk respond to the snake by identifying it?

Siberian chipmunks were presented with snakes and 4 control animals (tortoises, frogs, eels, quails) in a large outdoor pen to examine whether the snakedirected behavior of the chipmunk is a response to identifying the snake or simply an exploratory behavior toward generally strange objects. The animals were presented to chipmunks in 3 manners; tethered, anesthetized, and in perforated opaque boxes and in wire netting boxes. In “tethered” and “anesthetized”, chipmunks responded significantly more intensively to snakes than to other animals. When the animals were presented in the boxes, that is, when chipmunks could perceive only olfactory stimulus from the animals, they also showed the strongest response to snakes. The results suggest that 1) snake-directed behavior of chipmunks is not a general exploratory response toward strange objects but a response to identifying the snakes, and that 2) olfaction is an important cue for the chipmunks to identify snakes.     

Effects of putrescine and ethephon on some oxidative stress enzyme activities and proline content in salt stressed spinach leaves

The effects of putrescine and ethephon on peroxidase (POD; EC 1.11.1.7), polyphenol oxidase (PPO; EC 1.14.18.1), catalase (CAT; EC 1.11.1.6) activities and proline content in spinach leaves under saline stress were investigated. In control conditions, putrescine increased PPO and CAT activities and proline content, but decreased POD activity. Ethephon increased these three enzyme activities but did not affect proline content. In saline conditions, putrescine increased POD and CAT activities and proline content, while it decreased PPO activity. Ethephon increased both PPO and CAT activities and proline content, but decreased POD activity. Putrescine and ethephon have opposite effects on the enzyme activities and proline accumulation because they acts as antagonists.     

绿盲蝽取食与机械损伤对棉花叶片内防御性酶活性的影响

为探明绿盲蝽Apolygus lucorum (Mayer-Dür)取食和机械损伤对不同抗性棉花叶片内主要防御酶活性的影响以及防御酶与棉花抗绿盲蝽性的关系,以棉花3个不同抗性品系为材料,室内条件下测定绿盲蝽取食和机械损伤处理后棉叶中苯丙氨酸解氨酶(PAL)、过氧化物酶(POD)和多酚氧化酶(PPO)的活性.结果表明:对...     

Something different for dinner? Responses of a native Australian predator (the keelback snake) to an invasive prey species (the cane toad)

Predictions from foraging theory suggest that the probability a native predator will incorporate a novel type of prey (such as an invasive species) into its diet depends upon the potential benefits (e.g., nutrient input) vs. costs (e.g., handling time) of ingesting it. Cane toads (Bufo marinus) were introduced to Australia in 1935 and are highly toxic to many frog-eating snakes, thus there was strong selection to delete toads from the diet of these species. What has happened, however, to the feeding responses of an Australian snake species that is able to consume toads without dying? Our field surveys in northeastern Queensland show that, despite their high tolerance to toad toxins (compared to other native snakes), keelbacks (Tropidonophis mairii) feed primarily on native frogs rather than cane toads. This pattern occurs because the snakes show active prey preferences; even under standardized conditions in the laboratory, snakes are more likely to consume frogs than toads. When they are force-fed, snakes frequently regurgitate toads but not frogs. Thus, despite the high availability of the abundant toads, these invasive anurans are largely avoided as prey. This probably occurs because consumption of toads, although not lethal to keelbacks, causes significant sublethal effects and confers little nutritional benefit. Hence, keelback populations are not threatened by toad invasion, but neither do the snakes benefit substantially from the availability of a new type of potential prey.     

Past and Present Risk: Exposure to Predator Chemical Cues Before and after Metamorphosis Influences Juvenile Wood Frog Behavior

Animals are exposed to different predators over their lifespan. This raises the question of whether exposure to predation risk in an early life stage affects the response to predators in subsequent life stages. In this study, we used wood frogs (Rana sylvatica) to test whether exposure to cues indicating predation risk from dragonfly larvae during the wood frog larval stage affected post‐metamorphic activity level and avoidance of garter snake chemical cues. Dragonfly larvae prey upon wood frogs only during the larval stage, whereas garter snakes prey upon wood frogs during both the larval stage and the post‐metamorphic stage. Exposure to predation risk from dragonflies during the larval stage caused post‐metamorphic wood frog juveniles to have greater terrestrial activity than juvenile wood frogs that were not exposed to larval‐stage predation risk from dragonflies. However, exposure to predation risk as larvae did not affect juvenile wood frog responses to chemical cues from garter snakes. Wood frogs exposed as larvae to predation risk from dragonfly larvae avoided garter snake chemical cues to the same extent as wood frog larvae not exposed to predation risk from dragonfly larvae. Our results demonstrate that while some general behaviors exhibit carry‐over effects from earlier life stages, behavioral responses to predators may remain independent of conditions experienced in earlier life stages.     

Study of cystinaminopeptidase heterogeneity in animal sera by the isoelectric focusing method.

Study of the quantitative distribution of cystinaminopeptidase activity in the serum of pregnant and control animals (cow, sheep and rat) by the isoelectric focusing method showed heterogeneity of the cystinaminopeptidase activity of the animals' serum enzymatic system, which was well pronounced in the cow and rat and less pronounced in the sheep. The authors assume from their results that the principal difference between the pregnant and control animals is not the total increase in the level of activity of the enzyme in question, but the shift in its incidence, or the increase in activity at a given pH. It is possible that pregnancy, in man and animals, produces in the serum cystinaminopeptidase system (which is evidently heterogeneous even under normal, physiological conditions) given changes, i.e. the formation of new fractions with a different pI from the controls; other fractions disappear, or their activity diminishes.     

Comparative study of lipids and fatty acids in blood plasma of river lamprey Lampetra fluviatilis and brown frog Rana temporaria at the periods of elimination of exogenous feeding

Lipids of blood plasma of lampreys and frogs are composed of phospholipids, triglycerides, free fatty acids (FA), cholesterol, cholesterol esters, and waxes. The lipids content in plasma of frogs is markedly lower as compared with that of lampreys. However, the percentage of lipid components is represented by close values. Fluidity of triglycerides and phospholipids in lampreys is determined predominantly by monoenic acids and polyenoic acids of the ω-3-type, whereas that in frogs—by monoenic acids and polyenic acids of the ω-6-type. Free FA are represented mainly by saturated and monoenic acids.     

Inducibility and some properties of the threonine dehydratase of sheep liver

The threonine dehydratase extracted from sheep liver is in an essentially inactive form, referred to here as the precursor, but can be activated by incubation at high temperature in alkaline solution. A method for purification of the activated enzyme to a state approaching homogeneity has been devised. The activated enzyme catalyses the deamination of serine but rapidly loses activity during the process. The enzyme inactivated by incubation with serine can be reactivated under the same conditions as those described for the precursor, the kinetic parameters being the same in both cases. Individual sheep livers differ widely in their content of threonine dehydratase, and the possible role of dietary factors in this variability has been examined. The average amount of the enzyme in the livers of sheep fed on high-plant-protein diets did not differ significantly from that in livers obtained from slaughterhouses, but was higher than that in livers from animals fed only on grass or normal concentrates. Large increases in enzyme concentration were, however, obtained when sheep were injected intraperitoneally with a protein hydrolysate. The enzyme from the livers of these sheep could be purified by the same technique and to the same specific activity as the enzyme from the livers of control sheep.     

Influence of weather conditions on activity of tropical snakes

Abstract There are many anecdotal reports of massive day‐to‐day variation in activity levels of tropical reptiles and amphibians, and intuition suggests that weather conditions may be responsible for much of that variation. Our analysis of a large data set on the activity levels of tropical snakes and frogs confirms the existence of this short‐term variation in activity levels, reveals strong synchrony between sympatric taxa in this respect, but also shows that standard weather variables (temperature, humidity, precipitation, moonlight, atmospheric pressure) are surprisingly poor at predicting the numbers of individuals and species encountered during standardized surveys. We recorded the numbers of snakes and prey taxa (frogs) encountered on 349 nights over the course of one year on a 1.3‐km transect in the Adelaide River floodplain, in the wet–dry tropics of Australia. Frogs, water pythons (Liasis fuscus), slatey‐grey snakes (Stegonotus cucullatus) and keelbacks (Tropidonophis mairii) all showed strongly seasonal patterns of activity. After adjusting for seasonal differences, encounter rates were related to climatic conditions but different taxa responded to different weather variables. Water python activity was related to amount of moonlight, keelback activity was related to temperature, and frog activity was related to relative humidity, rainfall, temperature and moonlight. However, weather variables explained relatively little of the variation in activity levels. Strong synchrony was evident among encounter rates with various taxa (independent of season and weather conditions), suggesting that activity levels may be determined by other unmeasured factors.     

Glucose and free amino acids in the blood of lampreys (Lampetra fluviatilis L.) and frogs (Rana temporaria L.) under prolonged starvation

The content variation dynamics of glucose and free amino acids in blood plasma was followed for lampreys and frogs from autumn till spring, when the exogenous feeding is switched off. In October, the glucose level is rather high (8-10 mM) in blood plasma of both lampreys and frogs. It falls by 50% during winter and falls to a critically low level (1-2 mM) during spring. The lamprey plasma amino acid levels increase by 74% from November to April and thus reach the lower limit known for mammals. The amount of free amino acids in frog plasma decreases by 40% by spring in comparison with the values in autumn. More intensive proteolysis in lamprey tissues compared with that in frog tissues has been confirmed by quantitatively determining leucine, isoleucine, and valine in the blood of these animals. Besides these three amino acids, alanine, glycine, lysine, threonine and, in certain periods, tyrosine have been found to be quantitatively significant in the plasma of both animals.     

The impact of diet,habitat use,and behaviour on head shape evolution in homalopsid snakes

An organism's morphology is driven by selection on function while being constrained by phylogenetic and developmental factors as well as functional trade‐offs. If selection on function is strong and solutions limited, then convergence is expected. In this paper we quantify head shape in a group of ecologically diverse snakes (homalopsid snakes) differing in habitat use and diet using three‐dimensional geometric morphometric approaches. Using data on head shape we explore whether snakes eating different prey show different morphologies. Moreover, we test whether head shape is constrained by other factors such as habitat use, burrow use, or activity pattern. Our results demonstrate similar head shapes in species consuming similar prey. Snakes that capture elusive prey under water differ from those that capture and swallow prey like frogs or crustaceans. Moreover, habitat use, the use of burrows, and activity pattern also significantly impact head shape in this group of snakes. However, this signal appears to be partly confounded by the diet signal. For axes discriminating specifically between habitat use groups or animals that use burrows vs. those that do not shapes were in accordance with our predictions. Our results suggests an adaptive signal in the evolution of head shape in homalopsid snakes with diet, habitat use and the use of burrows all influencing the evolution of head shape in the group.     

Diet of the snake Philodryas nattereri (Steindachner, 1870) suggests a high plasticity of foraging in north-eastern Brazil

The knowledge about interactions between predators and prey is essential for understanding the natural history of animals, especially snakes, which are cryptic organisms that are difficult to visualize in the wild. This article reports on the predation of lizards, frogs, bats and venomous snakes by the snake Philodryas nattereri, evidencing its generalist feeding habits.     

Glutathione peroxidase activities in sheep and rat muscle and some effects of selenium deficiency.

The activity and distribution of the selenium-containing enzyme, glutathione peroxidase, has been determined in muscle fractions in normal adult rats and sheep. Skeletal and cardiac muscle have been examined, and in both types of muscle the major proportion of the enzyme appeared in the cytosol fraction. Enzyme activity was higher in cardiac muscle than in skeletal muscle in both species, and based on total protein present in fractions, it appears that rat muscle contains more enzyme activity than sheep muscle. In tissues from lambs born to selenium-deprived ewes the levels of enzyme were significantly depressed. Two sampling periods were selected, the first when the lambs were 2-3 weeks of age and the second at slaughter when they were 10 weeks old. Muscle, plasma and erythrocyte levels of the enzyme indicated that the most sensitive measure of selenium deficiency is likely to be that of the erythrocyte enzyme level.     

Active, inactive and in vitro synthesized forms of polyphenoloxidase during leaf development

Polyphenoloxidase (PPO; EC 1.14.18.1) activity decreased 8-fold from young to mature Vicia faba L. Moensch (cv. Long pod) leaves. The K_m for catechol remained relatively constant from young to mature leaves. Electrophoretic separation and analysis showed that only one active form was present in extracts from various leaf sizes. The amount of this form appeared to decrease with leaf size/age. In extracts which had not tanned, electroblotting and immunostaining indicated that one enzyme form was present with a molecular mass of 45 kDa. Two leaf categories contained greater amounts of this immunological cross-reacting PPO than other leaf categories. When extracts were allowed to darken, immunoblotting detected three enzyme forms with molecular masses of 45, 59 and 63 kDa. The latter two immunological crossracting species had no detectable enzyme activity. Poly-A⁺ mRNA was isolated from six leaf sizes and translated in vitro. A product corresponding to PPO was present in all leaf categories. Greater amounts of this translation product were observed in medium-sized leaves than in very young or mature leaves. These results suggest that: (1) enzymatic assays for PPO are not reliable indicators of the total amount of PPO protein present in developing leaves, (2) immunoblotting can detect inactive enzyme forms, (3) only one active form of the enzyme is present at all developmental stages, and (4) mRNA corresponding to PPO is present at all developmental stages but appears to be more abundant in certain leaf sizes/ages.     

Feeding preferences in 2 disjunct populations of tiger snakes, Notechis scutatus (Elapidae)

Variations at both the genetic and phenotypic levels play animportant role in responses to food and food-related stimuli.Knowledge of such variations is crucial to understanding howpopulations adapt to changing environments. We investigatedthe dietary preferences of 2 tiger snake populations and comparedthe responses of diet-naive animals (laboratory-born neonates),diet-controlled animals (laboratory-reared juveniles), and naturaldiet–experienced animals (wild-caught adults) to visualand chemical cues from 6 prey types (mouse, skink, silver gull,chicken, shearwater, and frog). The mainland population inhabitsa swamp, feeds mostly on frogs, and suffers heavy predation.The second population inhabits a small nearby offshore islandwith no standing water (no frogs); feeds mostly on skinks, mice,and, as adults, silver gull chicks; and suffers no known predation.Although different prey are eaten in the 2 populations, adultwild-caught snakes from both populations showed a significantpreference for 3 types of prey (frog, mouse, and chick), irrespectiveof their natural diet. Neonates responded to all prey cues morethan they did to control stimuli in both populations. However,the island neonates showed significantly higher interest insilver gull chick stimuli (the main prey of the island adultsnakes) than did their mainland conspecifics. Laboratory-bredjuveniles displayed behavioral plasticity by significantly increasingtheir response to mice after being fed baby mice for 7 months.We conclude that genetic-based differences in food-related cuesare important in tiger snakes but that they are also capableof behavioral plasticity. Island adult and neonate snakes exhibitedresponses to prey types no longer consumed naturally (frog),suggesting that behavioral characters may have been retainedfor long periods under relaxed selection. Island neonates showeda strong interest in a novel prey item (silver gull). This resultcomplements previous work describing how island snakes havedeveloped the ability to swallow larger prey than usual, aswell as seemingly developing a taste for them.