Complexity of lectins from the hard roe of perch (Perca fluviatilis L.)

Fish eggs are a rich source of lectins, the sugar-binding (glyco)proteins. In this paper we aim to further characterise perch roe lectins using several protein characterisation techniques including affinity chromatography and protein sequencing. Perch roe lectins are comprised of two subunits, subunit A and subunit B which have molecular weights of 12,400 and 12,000, respectively. These subunits form multiple aggregates A_nB_n in which the two subunits are present in differing ratios and, also as an `homogeneous' aggregates of one of the subunits A_n or B_n. Lectins A_n (designated A thereafter) and lectin B_n (designated B thereafter) formed by one type of subunit only (subunit A or B) were isolated in a pure state. Lectin B could also be isolated by spontaneous precipitation occurring during incubation of the perch roe extract at 4°C. Lectin B has a higher affinity for d-glucose than lectin A, whereas both lectins (A and B) have a similar affinity for l-fucose. The N-terminal region of subunit B showed the following amino acid sequence: EPAXPPWGTQFG-, whereas the N-terminus of subunit A was blocked and therefore could not be directly sequenced. Differences between subunits A and B were also found in amino acid composition. This unusual complexity and variability of perch roe lectins is likely to have physiological significance which, as yet, remains to be determined.     

L-fucose-specific lectin from pike perch (Lucioperca lucioperca L.) roe. Purification and studies of carbohydrate specificity

L-fucose-specific lectin was purified from pike perch (Lucioperca lucioperca L.) roe by affinity chromatography on ovariomucine H-sepharose from a human ovary cyst. Three bands were detected after disk-electrophoresis in PAAG in alkaline (pH 8.9) and five bands--in acidic system (pH 4.3). According to electrophoresis data in 15% SDS-PAGE the lectin contains two components with molecular weight 13-14 kDa. Molecular weight of the lectin is 50 kDa according to gel-chromatography on tojopearl HW-55. The immunochemical properties of the lectins from perch (Persa fluviatilis L.) roe and pike perch (Lucioperca lucioperca L.) roe are similar.     

Exceptionally big individual perch (Perca fluviatilis L.) and their growth

In Lake Windermere (U.K.) where there was a dense, slow-growing population of perch ( Perca fluviatilis L.) which had an l _x of about 180 mm, there co-existed a few individuals with an l _x of 463 mm. Data from 137 of these big perch, mostly caught in gillnets fishing for Esox lucius L., were examined. Their early growth was identical to that of normal perch, but, at an age, varying between individuals, from 1 to 8 and averaging 4 years, their growth accelerated for about 4 years and then followed a von Bertalanffy model with an l _x of 463 mm. They thus had a 'double' growth-curve that is revealed only if individual growth is examined. Acceleration tended to occur in certain calendar years and was correlated with strong year-classes of young perch. Growth was greater in years with warm summer water temperatures. There were no changes in the growth of big perch, after they had achieved 290 mm, during a period of great changes in the population density and an increase in the growth of normal perch < 290 mm. No more big perch were caught in Windermere between 1967 and 1990. Net selection, length-weight relationships, seasonal cycle in gonad weight, and opercular-body length relationship were the same as those of normal perch. The few available data suggest that big perch were piscivorous, feeding largely on small perch. The distribution of sites in the lake where big perch were caught is contagious, catches follow the negative binomial; but within fishings that caught big perch at the same site and time, catches were more evenly distributed than random. It is postulated that most adults would have accelerated their growth if they had sustained piscivory. Similar big perch have been found in other lakes.     

An application of a bioenergetics model to Eurasian perch (Perca fluviatilis L.)

A bioenergetics model was developed for Eurasian perch ( Perca fluviatilis L.) by revising an existing model for yellow perch and walleye. Data were gathered from field studies and the literature. Besides adjusting the original parameters of the model, effects of season on consumption and metabolic rates were added. The predictive capability of the revised model was high both concerning the levels of growth and its seasonal development in the Baltic coastal waters to which the model was applied. Perch young-of-the-year attained almost maximum consumption and growth except in the highest temperatures experienced. In larger fish, the model estimated consumption to be about 50 per cent of the maximum possible rate.     

Genetic and morphological divergence reveals local subdivision of perch (Perca fluviatilis L.)

The level of gene flow is an important factor influencing genetic differentiation between populations. Typically, geographic distance is considered to be the major factor limiting dispersal and should thus only influence the degree of genetic divergence at larger spatial scales. However, recent studies have revealed the possibility for small-scale genetic differentiation, suggesting that the spatial scale considered is pivotal for finding patterns of isolation by distance. To address this question, genetic and morphological differentiation were studied at two spatial scales (range 2–13 km and range 300 m to 2 km) in the perch ( Perca fluviatilis L.) from the east coast archipelago of Sweden, using seven microsatellite loci and geometric morphometrics. We found highly significant genetic differentiation between sampled locations at both scales. At the larger spatial scale, the distance per se was not affecting the level of divergence. At the small scale, however, we found subtle patterns of isolation by distance. In addition, we also found morphological divergence between locations, congruent with a spatial separation at a microgeographic scale, most likely due to phenotypic plasticity. The present study highlights the importance of geographical scale and indicates that there might be a disparity between the dispersal capacity of a species and the actual movement of genes. Thus, how we view the environment and possible barriers to dispersal might have great implications for our ability to fully understand the evolution of genetic differentiation, local adaptation, and, in the end, speciation.  © 2009 The Linnean Society of London, Biological Journal of the Linnean Society , 2009, 96 , 746–758.     

'Pear-shaped' cells in the digestive tract of the perch Perca fluviatilis (L.)

Light and electron microscopy revealed the presence of 'pear-shaped' cells amongst the mucosal cells of the stomach, pyloric curvature, pyloric caeca and the anterior-most region of the intestines of perch. The cells are usually located in the distal region of the mucosa and are approximately half the height of the other mucosal cells. Electron microscopy shows that the cells are composed of thick outer sheaths which are fibrillar in appearance. The cytoplasm is characterized by electron dense rods numbering from three to fifteen, which originate from the supranuclear region of the cells and converge apically. The rest of the cytoplasm is composed of Golgi apparatus, secretory vacuoles, minute mitochondria and a network of cytoplasmic strands laden with ribosomes. The organization of organelles in these cells does not resemble that of other mucosal cells of the alimentary canal. Contrary to what has been suggested previously, the 'pear-shaped' cells neither resemble nor represent stages in the formation and maturation of goblet cells.     

The age and growth of perch (Perca fluviatilis L.) in two Scottish lochs

This study is concerned with the age and growth of perch ( Perca fluviatilis L. ) in two contrasting Scottish lochs-the Dubh Lochan and Loch Lomond. Age and back-calculated growth were determined from annual rings in the opercular bones, and during the 2-year project 470 perch from the Dubh Lochan and 796 from Loch Lomond were examined. Growth in length in the two lochs, though similar for the first 2 years, differed thereafter, the average length at 8 years in the Dubh Lochan being less than 15 cm, that in Loch Lomond more than 23 cm at the same age. In neither locality did the growth of perch follow the Von Bertalanffy growth formula. Reasons for differential growth rates are discussed and comparisons made with the growth of perch in other waters in Europe and North America.     

Local growth differences in perch (Perca fluviatilis L.) in a Baltic archipelago

Data on the chemical composition of the hard water rivers Rhine and Rhone, published elsewhere, are stored in a new data bank, RRQUE. In this paper the seasonal variation in pH and concentrations of calcium, bicarbonate and sulphate at 7 stations in the Rhine and 7 in the Rhone are described. The concentrations of calcium, bicarbonate and sulphate show important increases with increasing distance from the source. In both rivers acidification gradually occurs downstream and is thought to be caused by the decomposition of disposed organic matter. It is shown that the normal seasonal patterns of these 4 chemical variables are negated by anthropogenic effects.     

The feeding behaviour of large perch Perca fluviatilis (L.) in relation to food availability: a comparative study

Hydrobiologia - The aim of the present study was to analyse and compare the feeding behaviour of large perch (&gt;25 cm total length) in two lakes of different state and corresponding...     

Fecundity and reproduction of perch (Perca fluviatilis L.) in Lake Agios Vasilios, Greece

SUMMARY. In Lake Agios Vasilios, male perch become sexually mature during their first year of life whereas females become sexually mature during their second year. The mean absolute fecundity was 8080 eggs; values ranged from 2080 to 28488. The mean relative fecundity was 141 eggs/g body wet weight (ranging from 113 to 201). The absolute increase in weight of gonads is related to the age of the fish. The spawning period is from the middle of March to the beginning of April, at a mean water temperature of 8°C.     

Differences in growth of perch (Perca fluviatilis L.) in two small forest lakes

Growth patterns and food composition of perch, Perca fluviatilis L., was studied in two small forest lake populations in southern Finland. Size and morphometry of the lakes and physical and chemical properties of water are similar. There is a clear difference in the growth rates of perch between the two lakes. The difference in growth is highly significant in all age groups. In the first lake there is a perch population of 2 000 (1750 ind · ha^–1) adult fishes. In the second lake there is a small population of pike, that keeps the perch population down: 200 adult perch (530 ind · ha^-1). The main food items of perch are crustacean zooplankton, Asellus aquaticus L. and Trichoptera larvae in the first lake and zooplankton, Odonata larvae, Ephemeroptera larvae and Heteroptera in the second.It is concluded that the main reason for the growth difference of studied perch populations is the different population density. There are also differences in species composition of bottom fauna of the lakes, maybe owing to the floating Sphagnum peat moss vegetation in the second lake. This can also affect the growth difference between the two populations of perch.     

A contribution to the knowledge of the stunted growth of perch (Perca fluviatilis L.) in Holland

Summary The stunted growth of the Dutch perch was studied. To calculate the age and former growth the winterrings of the scales were used. The excellent growth of perch in some parts of Holland in contrast to the bad growth reported by foreign authors is discussed. It is pointed out that the latter growth may be ascribed to the existence of false winterrings, from which one can get rid by dipping the scales in a HCl-solution.It appeared that the initial growth of the stunted perch up to about 13 cm is good. The stunted growth afterwards must be ascribed to a shortage of prey-fish. Especially the smelt seems to be very important. As, however, in Holland young roach are abundant it seems incomprehensible why these cannot serve for suitable perch-food. To investigate this problem the conduct of hunting perch was studied in an aquarium.The results of the aquarium-experiments were in agreement with the change in food-diet at a certain length discussed by other authors; also with the assumption that middle-sized perch do not prey upon smaller congeners.Concerning the preying upon roach it became clear that a single perch will scarcely or not succeed in seizing a roach. The hunting is accomplished by cooperation in open water stretches. Amidst plants perch does not hunt. Hence the stunted growth of perch in Holland must be ascribed to the many plants in Dutch waters, between which the roach may easily escape hunting by perch.A short comparison of prey-sizing by wels, pike pike-perch and perch is made.     

Ultrastructure of muscle fibres in head and axial muscles of the perch (Perca fluviatilis L.)

Summary White, pink, red and deep red fibres, selected from a head muscle and from axial muscles of the perch, show significant differences in actin filament length, Z line thickness, Z line lattice space, myofibril girth, the percentages volume occupied by T system and terminal cisternae of the SR, and in the degree of T system SR contact per sarcomere. In both muscles the degree of T system SR contact decreases in the order: white, pink, red, deep red, which suggests a decrease of contraction velocity in the same order.The position of the T system (at the Z line or at the AI junction) is related to the actin filament length. The actin filaments in the red fibres are appreciably longer than in the white, which suggests that the sarcomeres of the red fibres have a broader length-tension curve. The Z line thickness is positively correlated with the actin filament length and, in the white and the red fibres, negatively with the degree of sarcomere shortening. Thicker Z lines are suggested to allow greater sarcomere sizes (length or girth).The percentage volume occupied by mitochondria varies independently of the extent of membrane systems.The ultrastructural characteristics of the fibre types are in agreement with the functional roles as reported in literature.     

Purification and characterization of a lectin from wild sunflower (Helianthus tuberosus L.) tubers

A lectin (HTTL) was isolated from Helianthus tuberosus L. (wild sunflower) tubers using ion-exchange chromatography, gel filtration, and affinity chromatography. The lectin agglutinated both untreated and trypsin-treated rabbit erythrocytes and did not agglutinate human blood cells of groups A, B, and O. The gel filtration showed the native molecular mass of 72 kDa and subunit molecular masses of 17 and 18.5 kDa on 12% SDS-PAGE. The lectin activity was inhibited by D-mannose. The tetrameric protein revealed a unique characteristic by forming a broad zone of protein in native PAGE at pH 8.3, which dissociated into seven subunits of varying e/m ratios on acid gel at pH 4.3. These seven bands revealed two polypeptide species of molecular masses 17 and 18.5 kDa on 12% SDS-PAGE, as in the case of the native protein. The result indicated that of the seven subunits, three were homotetramers of 17 kDa, one was a homotetramer of 18.5 kDa, and three were heterotetramers of 17 and 18.5 kDa. The lectin was thermostable with broad pH optima (pH 4-8) and had no requirement for divalent metal cations for its activity. The amino acid composition showed that the lectin contained higher amounts of glycine, alanine, and lysine, but no methionine. The sugar content was estimated to be 5.3% mannose equivalent. The HTTL was mitogenic to mouse spleen (total) cells at 25 microg/ml concentration. The lectin showed characteristics different from those of the earlier reported H. tuberosus tuber lectins and hence opens up a new avenue to investigate the structure-function relationship of lectin in Helianthus species.     

Purification of an N-acetyl-D-glucosamine specific lectin (P.B.A.) from epidermal cell membranes of Pieris brassicae L

We report the isolation and the purification of an N-acetyl-D-glucosamine specific lectin capable of agglutinating either fixed trypsinized rabbit erythrocytes or chitin particles. An agglutinin assay based on the affinity of this lectin for the chitin was devised with fluorescent particles of scorpion cuticle to measure lectin activity during purification steps. Lectin was isolated from epidermal cell membranes; its molecular weight was determined by gel filtration and polyacrylamide electrophoresis in sodium dodecyl sulfate. Mr was estimated to be 43,000. Lectin could be constituted by two subunits. Mr of which was estimated to be 23,000. The specificity of this lectin against N-acetyl-D-glucosamine and its oligomers suggests a possible role in the dynamics of these saccharides during the cuticle cycle.     

Distribution of perch (Perca fluviatilis L.) during their first year of life in Lake Constance

The distribution and behaviour of larval and juvenile perch (Perca fluviatilis L.) were studied for two years in large, deep Lake Constance. After hatching larvae were transported by water currents to the open water. The majority of larvae remained in the pelagic zone for about one month. In both years, their return to the littoral zone coincided with the decline of pelagic zooplankton abundance. After returning to the littoral zone, juveniles stayed among submerged macrophytes within 5 m depth and lived apart from larger perch which lived at depths of 6–20 m. By late summer, juveniles changed their distribution pattern: during the day they stayed intensively close to piers and ports, but increased their swimming activity at dusk, cruising among shallow and deep waters and feeding on zooplankton, and rested on the bottom at night. This behaviour appears to be related to the decrease of inshore food resources and to the presence of predators in deeper water. 0⁺ perch left the littoral zone and moved into deep waters when autumnal mixing began in late October. They overwintered near the bottom at depths of more than 30 m. During most of the year, juvenile and adult perch were separated from each other. But as soon as they occupied the same habitat, the occurrence of cannibalism increased.     

Purification and characterization of an N-acetyl-D-galactosamine-specific lectin from seeds of chickpea (Cicer arietinum L.)

A novel lectin (CAA-II) was isolated and purified from the seeds of Cicer arietinum by ammonium sulphate fractionation and affinity chromatography on an N-acetyl-D-galactosamine-linked agarose column. The lectin is composed of four identical subunits of 30 kDa and the molecular mass of the native lectin was estimated to be 120 kDa by gel filtration chromatography and confirmed by mass spectrometry. The lectin showed agglutination activity against rabbit erythrocytes (trypsin-treated and untreated) as well as against human erythrocytes. Haemagglutination inhibition assays showed that the lectin is a galactose-specific protein having a high affinity for N-acetyl-D-galactosamine. The molecular weight, haemagglutination pattern, carbohydrate specificity and N-terminal amino acid sequence indicated that the lectin is clearly distinct from the previously reported chickpea lectin CAA-I.     

Purification and study of carbohydrate specificity of lectin from Sarcoscypha coccinea (Fr.) Lambette

A lectin that revealed affinity for lactose, N-acethylactosamine, 4-nitrophenyl-beta-D-gluco- and galactopyranosides from fruiting bodies of Sarcoscypha coccinea (Fr.) Lambette was purified by affinity chromatography on immobilized ovomucoid. According to electrophoresis data in 15% SDS-PAGE the lectin contains two very low-differing components with molecular weight 32 kDa. Molecular weight of the lectin is 128 kDa according to gel-chromatography on sephadex G-200. The lectin agglutinates rabbit erythrocytes and slightly weaker agglutinates human erythrocytes. After dialysis against 1% EDTA sodium salt solution the lectin loses hemaglutinating activity, but after the next dialysis against CaCl2 solution it is restored.     

The predation on Asellus aquaticus (L.) by perch,Perca fluviatilis (L.), in a small forest lake

Asellus aquaticus (L.) was the most important benthic food item for perch, Perca fluviatilis (L.), in a small, extremely humic forest lake in southern Finland. The proportion of A. aquaticus in the diet of perch varied according to the former's availability, which, in turn, depended on its life cycle. Perch 11.0–12.9 cm (total length) most frequently fed on A. aquaticus; smaller and larger perch fed more frequently on crustacean zooplankton and aquatic insect larvae, respectively. The high density of the perch population, the importance of A. aquaticus in the benthos of the study lake and the general high activity level of the prey resulted in a high predation (0.1–1.8% per day). The population of A. aquaticus was also limited by the scarcity of macrophytic vegetation and the small area of oxygenated littoral in the lake.