Variabilité et différenciation génétiques chez cing espèces d'ecrevisses Astacidae

Analysis of fifteen loci encoding enzymes has shown an important differentiation between five European and North American species of the Astacidae. Evaluation of the genetic distances revealed that closely related species are on the one hand, Orconectes limosus and Procambarus clarkii and, on the other, Astacus astacus and Astacus leptodactylus. This analysis brings no genetic justification for the separation of these five species into two sub-families. However, the distinction between the genera Astacus and Austropotamobius seems confirmed. The possibility of a correlation between heterozygosity and oxygen consumption is evocated.     

Quantitative aspects of carotenoid pigment circadian variations in the crayfish Astacus leptodactylus

The carotenoid pigment concentrations of whole animal, epidermis and hepatopancreas of the crayfish Astacus leptodactylus were studied every three hours during a period of 24 h. The extract of whole animal exhibits a total pigment concentration which remains noticeably stable. Circadian variations were observed in extracts from the hepatopancreas and epidermis; the maxima observed for the epidermis as well as the minima recorded for the hepatopancreas are related to the alternating light and dark periods. The symmetry of such variations suggests a transfer of pigment between the two tissues.     

Localization of crustacean hyperglycemic hormone (CHH) in the X-Organ sinus gland complex in the eyestalk of the crayfish,Astacus leptodactylus (Nordmann, 1842)

The eyestalk of Astacus leptodactylus is investigated immunocytochemically by light, fluorescence, and electron microscopy, using an antiserum raised against purified crustacean hyperglycemic hormone (CHH). CHH can be visualized in a group of neurosecretory perikarya on the medualla terminalis (medulla terminalis ganglionic X-organ: MTGX), in fibers forming part of the MTGX-sinus gland tractus, and in a considerable part of the axon terminals composing the sinus gland. Immunocytochemical combined with ultrastructural investigations led to the identification of the CHH-producing cells and the CHH-containing neurosecretory granule type.     

Population structure and genetic analysis of narrow-clawed crayfish (Astacus leptodactylus) populations in Turkey

The genetic differentiation among Turkish populations of the narrow-clawed crayfish was investigated using a partial sequence of cytochrome oxidase subunit I gene (585 bp) of 183 specimens from 17 different crayfish populations. Median joining network and all phylogenetic analyses disclosed a strong haplotype structure with three prominent clades diverged by a range between 20 and 50 mutations and substantial inter-group pairwise sequence divergence (5.19–6.95 %), suggesting the presence of three distinct clades within the Anatolian populations of Astacus leptodactylus. The divergence times among the three clades of Turkish A. leptodactylus are estimated to be 4.96–3.70 Mya using a molecular clock of 1.4 % sequence divergence per million years, pointing to a lower Pliocene separation. The high level of genetic variability (H _d  = 95.8 %, π = 4.17 %) and numerous private haplotypes suggest the presence of refugial populations in Anatolia unaffected by Pleistocene habitat restrictions. The pattern of genetic variation among Turkish A. leptodactylus populations, therefore, suggests that the unrevealed intraspecific genetic structure is independent of geographic tendency and congruent with the previously reported geographic distribution and number of subspecies (A. l. leptodactylus and A. l. salinus) of A. leptodactylus.     

N-acetylmuramic acid in mollusca gastropoda: a histochemical and immunocytochemical study

Summary The presence of N-acetylmuramic acid in glycoconjugates in various mollusc tissues was investigated by histochemical and immunocytochemical techniques. The tissues studied included foot, mantle, digestive gland, ganglia and haemocytes ofHelix aspersa, Planorbarius corneus, Murex brandaris andTrunculariposis trunculus. Sialic acid residues were found to be absent. The possibility that N-acetylmuramic acid replaces sialic acid in acid glycoconjugates of gastropods with similar properties is discussed.     

Evaluation of metabolic changes induced by polyphenols in the crayfish <Emphasis Type="Italic">Astacus leptodactylus</Emphasis> by metabolomics using Fourier transformed infrared spectroscopy

In the present study, the effects of polyphenols on the chemical composition of the hepatopancreas of the Astacus leptodactylus, a highly sought farmed crayfish, have been investigated by attenuated total reflectance–Fourier transform infrared (ATR-FTIR) spectroscopy. The hepatopancreas spectrum was quite complex and contained several peaks arising from the contribution of different functional groups belonging to protein, lipids and carbohydrates. The PCA statistical analysis revealed that there were significant differences between crayfish fed a diet without polyphenols and crayfish fed a diet containing polyphenols. Such differences indicated an increase in lipids and proteins in the hepatopancreas of polyphenol-fed crayfish. In conclusion, the analysis of the infrared spectral profile of the hepatopancreas of Astacus leptodactylus, allowed us to elucidate the changes in different biomolecules in response to polyphenol treatment, and confirms the suitability of ATR-FTIR spectral data to analyze diet-induced metabolic effects. These considerations, coupled with the small amount of sample and no preparation needed, make ATR-FTIR a useful tool for routine analyses where the metabolic impact of substances is investigated, especially with a large number of samples.     

Evolution des acides amines libres seriques

Qualitative and quantitative variations of free amino acids have been examined in the serum of Astacus leptodactylus during progressive osmotic adaptation and hyperosmotic stress. Free amino acids hardly participate in the extracellular osmotic regulation. Their variation in the serum is correlated to the fluctuations of the intracellular free amino acids during isosmotic regulation.     

A novel approach to the measurement of surfactant parameters in arthropod digestive juices

In arthropods, the determination of two important parameters of digestive juices, i.e. the total surfactant concentration and the critical micelle concentration (CMC), is challenging due to small sample volumes and low surfactant concentrations. In this work, we report a successful implementation of potentiometric titrations using the surfactant ion-selective electrode (SISE) and the pyrene fluorescence method (PFM) for the determination of the total surfactant concentration and CMC in the digestive juice of terrestrial isopod crustaceans Porcellio scaber. Pooled digestive juice extracts of four (SISE) or two (PFM) animals were used per measurement run. In both cases, digestive juice extracts in 100 μL of deionized water were sufficient for one measurement run. The total surfactant concentration of P. scaber digestive juice was determined to be 9.2 ± 3.5 mM and the CMC was approximately 90 μM. Our work presents an important improvement towards easy CMC determination in small volume samples in comparison with the commonly used stalagmometric technique, where much larger sample volumes are usually needed. To date, the total surfactant concentration was not measured in the digestive juices of arthropods other than Homarus vulgaris, Astacus leptodactylus and Cancer pagurus, for which complex separation and analytical techniques were required. Our results obtained by SISE and PFM therefore present the first successful quantification of surfactants and their CMC in small volumes of arthropod digestive juice without prior separation or purification techniques.     

Vergleichende Untersuchungen zur Herztätigkeit bei frei beweglichen dekapoden Krebsen (Astacus fluviatilis Fab., Astacus leptodactylus Eschscholz und Cambarus affinis Say)

Zusammenfassung Mit Hilfe von Pt-Aspirationselektroden wurde das Verhalten des Krebsherzens an frei beweglichen, ungestörten Astacus fluviatilis, Astacus leptodactylus und Cambarus affinis gegenüber Temperatureinflüssen untersucht. Die angewandte Methode erlaubt eine lückenlose Registrierung der Herztätigkeit über einen längeren Zeitraum. Die Herzfrequenzen folgen der R-G-T-Regel bei Astacus fluviatilis zwischen 0 und 26° C, bei Astacus leptodactylus zwischen 0 und 28° C und bei Cambarus affinis von 0–30° C. Die Letaltemperaturen liegen bei ca. 28, 34 bzw. 37° C; der Q ₁₀ bei 1,7, 1,9 bzw. 1,8. An höhere Temperaturen adaptierte Individuen zeigen eine signifikant höhere Herzfrequenz in höheren Temperaturbereichen als die an tiefere Temperaturen adaptierten. Jungtiere geringen Gewichts (2,5 g) weisen eine signifikant höhere Herzfrequenz auf als die schwereren adulten Tiere (ca. 90 g).

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Comparative experiments on the heartbeats of unrestrained decapode crustaceans (Astacus fluviatilis Fab., Astacus leptodactylus Eschscholz, and Cambarus affinis Say)

Summary The temperature influence on the heartbeats of unrestrained Astacus fluviatilis, Astacus leptodactylus, and Cambarus affinis has been studied by means of aspiration electrodes. This method allows a complete and long termed registration of the heartbeats. The rule of van t'Hoff has been proved for the heartbeat frequencies of Astacus fluviatilis between 0 and 26° C, of Astacus leptodactylus between 0 and 28° C, and of Cambarus affinis from 0–30° C. Lethal temperatures have been found at about 28° C, 34° C, and 37° C respectively, the Q ₁₀ was measured as 1.7, 1.9, and 1.8 respectively. Warm adapted specimen show a significant higher frequency at higher temperatures than cold adapted ones. Young individuals of little weight (2.5 g) have been found to posses a marked higher frequency than the heavier adult animals (90 g).

     

Appearance and innervation of CHH-producing cells in the eyestalk of the crayfish Astacus leptodactylus examined after tracing with Lucifer Yellow

Summary By injection of the fluorescent dye Lucifer Yellow into individual Crustacean Hyperglycemic Hormone (CHH)-producing cells, the shape of these neurosecretory cells in the eyestalk of the crayfish Astacus leptodactylus can be traced. A highly fluorescent perikaryon gives rise to an axon that can be followed by the fluorescent label to the neurohemal region, the sinus gland. The proximal part of that axon sends out extensive branches into the neuropil of the medulla terminalis. Electron-microscopic investigations reveal synaptic input to these axonal ramifications.     

Glutathione enzymes,glutathione content and t-butyl hydroperoxide induced lipid peroxidation in the gill and digestive gland of the estuarine clam,Rangia cuneata

1. Reduced glutathione (GSH), glutathione reductase (GSSG-reductase) and glutathione peroxidase (GSH-peroxidase) activities were measured in the gill and digestive gland of Rangia cuneata.2. Substantial GSH concentrations were found in both gill (820 ± 80 nmole/g tissue) and digestive gland (930 ± 130 nmole/g tissue). The digestive gland exhibited 2.5-fold greater GSSG-reductase activities and 0.5-fold lower GSH-peroxidase activities relative to the gill.3. In vivo exposure to t-butyl hydroperoxide (BHP) elicited a dose-dependent increase (P < 0.05) in lipid peroxidation in both tissues. Lipid peroxidation occurred earlier and to a greater extent in the digestive gland versus the gill. GSH concentrations in both tissues were unaffected by BHP exposure.4. The study results indicate that gill and digestive gland differ in susceptibility to BHP induced oxidative damage, and the difference is accounted for by differences in tissue GSH metabolism.     

A comparative study of the physiological condition of native and invasive crayfish in Croatian rivers

The physiological condition of two invasive crayfish species identified in Croatian rivers (Orconectes limosus and Pacifastacus leniusculus) was compared with that of native crayfish populations (Astacus astacus and A. leptodactylus). Hepatosomatic, gonadosomatic and abdominal muscle indices were examined for all four species and within a specific invadernative pair. The results demonstrate that invasive crayfish had better overall physiological condition when compared to native species, with a higher energy content of the hepatopancreas, abdominal muscle and gonads in invasive than in native species, with the exception of A. leptodactylus females which demonstrated an increased ability to allocate energy to reproduction in comparison with other species. These results also indicate that A. astacus is physiologically more unstable than A. leptodactylus and thus more likely to be outcompeted and replaced by non-indigenous crayfish species.     

Etude ultrastructurale de l'ovocyte en vitellogenèse chez les Ecrevisses Astacus astacus et A leptodactylus

In crayfish Astacus astacus and A. leptodactylus, protein yolk materials appear to be derived from intra- and extra-oocytic sources.     

Accumulation and excretion of aluminium and iron by the terrestrial snail Helix aspersa

1. The snail Helix aspersa was fed one 24 hr meal containing Al, Fe or both together in barley flour pellets. Accumulation and distribution within the digestive gland, kidney, crop and remaining soft tissues were examined over the subsequent 30 days using atomic absorption spectroscopy (A.A.S.).2. The digestive gland contained significantly (P < 0.05) elevated levels of Al and Fe for 8 and 12 days. The digestive gland is the major sink for both Al and Fe in Helix.3. The kidney rapidly accumulated Al and Fe but the increase was short-lived. The kidney may therefore be involved in the elimination of metal not incorporated into the digestive gland.4. Iron was absorbed by the crop but Al was not. This may indicate a route of uptake of Fe into the digestive gland not shared with Al.5. No obvious pattern of accumulation of Al and Fe were seen in the remaining soft tissues or the blood of Helix.6. Aluminium is present in the faeces for 12 days suggesting that Al is released relatively slowly.7. Presence of both Al and Fe in the feed induced a change in the pattern of accumulation in the digestive gland but not in the kidney, crop and remaining soft tissues.8. The distribution of Al is discussed in relation to the suggestion that Al follows the ferretin pathway during accumulation.     

A comparative immunocytochemical investigation of the crustacean hyperglycemic hormone (CHH) in the eyestalks of some decapod crustacea

The eyestalk of the astacideans Orconects limosus, Nephrops norvegicus, and Homarus gammarus, and the palinuran Palinurus vulgaris, was examined with an antiserum raised against purified crustacean hyperglycemic hormone (CHH) of the astacidean species Astacus leptodactylus. A distinct immunopositive reaction occurs in a group of neurosecretory cells in the medulla terminalis ganglionic X-organ (MTGX), in the MTGX-sinus gland tractus, and in a considerable part of the sinus gland. The immunoreactive sites in the eyestalk of the investigated species correspond to the site of production, storage, and release of the CHH. Preliminary investigations with this antiserum also indicate that a positive immunoreaction can be obtained in the eyestalk of other decapod crustaceans, for example, of the brachyuran Macropipus puber and the caridean Palaemon serratus.     

The harvest of freshwater crayfish, <Emphasis Type="Italic">Astacus leptodactylus</Emphasis> (Eschscholtz, 1823) in Turkey

Astacus leptodactylus is naturally and widely distributed in lakes, ponds and rivers throughout of Turkey. It has also been stocked in many freshwater systems in Turkey to establish new populations and to restore crayfish stocks devastated by the plague (Aphanomyces astaci) and some other reasons (i.e., farming and culinary purposes). Human consumption of A. leptodactylushas always been very low in Turkey; therefore, it was exported mainly to Europe until 1986. A plague was observed in 1985 in Eğirdir, Apolyont, Sapanca and Manyas lakes which included the main harvest areas, and the fishery was lost within 2 years. Consequently, crayfish harvest was banned in all populations to control the plague. Because of the plague, over-fishing and pollution, the harvest of A. leptodactylusin Turkey declined from approximately 5000 (1984) to 200 (1991) tons annually. In 2000s, there has been a gradual increase in the rate of harvest of A. leptodactylusin Turkey, reaching approximately 1600–1900 tons annually, but the plague is still observed in this species at certain localities. The present study reveals that A. leptodactylus in Turkey needs professional support for recovery, because the present harvest of A. leptodactylusis still nearly 20% of the crayfish catch in 1980s.     

Fatty acid profile of the digestive gland and mantle in the bivalve Macoma balthica

• 1.1. Digestive gland and mantle fatty acids were studied in spring and summer in the bivalve Macoma balthica off the southern coast of Finland. The presence of lipids was also examined histochemically in various clam tissues.
• 2.2. the neutral lipid content of the digestive gland increased ca 4.5-fold during the annual growth period.
• 3.3. Neutral lipid fatty acids of the digestive gland, of which palmitoleic, eicosapentaenoic and palmitic acids were predominant, were clearly distinguished from phospho- and glycolipid fatty acids.
• 4.4. The degree of unsaturation of phospholipid fatty acids was higher in the cold season both in the digestive gland and mantle, mainly due to the titer of eicosapentaenoic acid.

     

Swelling of mitochondria in crayfish gills

Summary In the gill processes ofAstacus leptodactylus Esch. fixed in the hypotonic glutaraldehyde fixative the mitochondria appear swollen to a different extent. The swelling occurs in a special way. Part of a single mitochondrion is swollen and the remaining part is frequently unchanged as in the control sections made of tissues fixed in the isotonic fixative. It is concluded that the mitochondrial matrix occurs in a semisolid state and osmotic swelling begins as a local liquefaction of the matrix which extends gradually over the total mitochondrion.