A biologically active peptide in the skin of lampreys (Eudontomyzon danfordi vladykovi). [Translation from: Z.Naturforsch. (B), 26(10), 1021-1023, 1971. ]

In recent years interest in the production and description of kinin-type substances has been greatly intensified. So, for example, bradykinin, phyllokinin, physalaemin, ranatensin and caerulein could be extracted from the skin of amphibians as well as. eledoisin out of the salivary glands of Eledon moschata. An examination of lampreys seemed to us particularly profitable in the search for the incidence of further kinins. Ammocoetes of different sizes and also adults of both sexes of the species Eudontomyzon danfordi vladykovi were studied in this research. This species is found in many tributaries of the Danube. Skin extracts were tested on on isolated rat uterus, rat duodenum, guinea pig ileum and rabbit jejunum, further tests were done in order to determine a peptide character of the biologically active substance.

Investigations into the structure and function of the exocrine pancreas of lampreys. [Translation from: Morph.Jb. 110 245-269, 1967.]

As representatives of the most primitive of recent vertebrate groups, lampreys show fundamental differences in different features of organisation to the species of the remaining classes of vertebrates. The topical distinction between exocrine and endocrine pancreas is also considered among the morphological peculiarities of Petromyzontida. This study aims to contribute to a further explanation of this phenomenon. 50 brook lampreys were histologically examined.

Downstream movement of lampreys and fishes in the Carp Lake River, Michigan /

Includes bibliographical references (page 3).

European lampreys: new insights on postglacial colonization, gene flow and speciation.

Ice ages are known to be the most dominant palaeoclimatic feature occurring on Earth, producing severe climatic oscillations and consequently shaping the distribution and the population structure of several species. Lampreys constitute excellent models to study the colonization of freshwater systems, as they commonly appear in pairs of closely related species of anadromous versus freshwater resident adults, thus having the ability to colonize new habitats, through the anadromous species, and establish freshwater resident derivates. We used 10 microsatellite loci to investigate the spatial structure, patterns of gene flow and migration routes of Lampetra populations in Europe. We sampled 11 populations including the migratory L. fluviatilis and four resident species, L. planeri, L. alavariensis, L. auremensis and L. lusitanica, the last three endemic to the Iberian Peninsula. In this southern glacial refugium almost all sampled populations represent a distinct genetic cluster, showing high levels of allopatric differentiation, reflecting long periods of isolation. As result of their more recent common ancestor, populations from northern Europe are less divergent among them, they are represented by fewer genetic clusters, and there is evidence of strong recent gene flow among populations. These previously glaciated areas from northern Europe may have been colonized from lampreys expanding out of the Iberian refugia. The pair L. fluviatilis/L. planeri is apparently at different stages of speciation in different locations, showing evidences of high reproductive isolation in the southern refugium, and low differentiation in the north.

Do non-native invasive fish support elevated lamprey populations?

Summary
1: Managing populations of predators and their prey to achieve conservation or resource management goals is usually technically challenging and frequently socially controversial. This is true even in the simplest ecosystems but can be made much worse when predator–prey relationships are in?uenced by complex interactions, such as biological invasions, population trends or animal movements.
2: Lough Neagh in Northern Ireland is a European stronghold for pollan Coregonus autumnalis, a coregonine ?sh and for river lampreyLampetra ?uviatilis, which feeds parasitically as an adult. Both species are of high conservation importance. Lampreys are known to consume pollan but detailed knowledge of their interactions is scant. While pollan is well known to be a landlocked species in Ireland, the life cycle of normally anadromous river lamprey in Lough Neagh has been unclear. The Lough is also a highly perturbed ecosystem, supporting several invasive, non-native ?sh species that have the potential to in?uence lamprey–pollan interactions.
3: We applied stable isotope techniques to resolve both the movement patterns of lamprey and trophic interactions in this complex community. Recognizing that stable isotope studies are often hampered by high-levels of variability and uncertainty in the systems of interest, we employed novel Bayesian mixing models, which incorporate variability and uncertainty.
4: Stable isotope analyses identi?ed troutSalmo trutta and non-native breamAbramis brama as the main items in lamprey diet. Pollan only represented a major food source for lamprey between May and July.
5: Stable isotope ratios of carbon in tissues from 71 adult lamprey showed no evidence of marine carbon sources, strongly suggesting that Lough Neagh is host to a highly unusual, nonanadromous freshwater population. This ?nding marks out the Lough’s lamprey population as of particular scienti?c interest and enhances the conservation signi?cance of this feature of the Lough.
6: Synthesis and applications.Our Bayesian isotopic mixing models illustrate an unusual pattern of animal movement, enhancing conservation interest in an already threatened population. We have also revealed a complex relationship between lamprey and their food species that is suggestive of hyperpredation, whereby non-native species may sustain high lamprey populations that may in turn be detrimental to native pollan.Long-term conservation of lamprey and pollan in this system is likely to require management intervention, but in light of this exceptional complexity, no simple management options are currently supported. Conservation plans will require better characterization ofpopulation-level interactions and simulation modelling of interventions. More generally, our study demonstrates the importance of considering a full range of possible trophic interactions, particularly in complex ecosystems, and highlights Bayesian isotopic mixing models as powerful tools in resolving trophic relationships.
Key-words: Bayesian, conservation dilemma, Coregonus autumnalis, hyperpredation, Lampetra ?uviatilis, pollan, potamodromous, River lamprey, stable isotope analysis in R, stable isotope

A PRELIMINARY ASSESSMENT OF THE DISTRIBUTION OF THE SEA LAMPREY (PETROMYZON MARINUS L.), RIVER LAMPREY (LAMPETRA FLUVIATILIS (L.)) AND BROOK LAMPREY (LAMPETRA PLANERI (BLOCH)) IN NORTHERN IRELAND

Lampreys are endangered in Europe, and European states are legally required to take measures to ensure their protection. However, there is currently little information on the distribution of the three species present in Northern Ireland. Anecdotal records of adult lampreys were collated from anglers and other sources, and a systematic electrofishing survey was undertaken to establish the distribution of lamprey ammocoetes. Lampreys were found in seven of the nine Northern Irish river catchments. Brook lampreys (Lampetra planeri (Bloch)) were widely distributed, but the two anadromous species, sea lamprey (Petromyzon marinus L.) and river lamprey (Lampetra fluviatilis (L.)), were more limited in their distribution, possibly due to barriers restricting migration.

An endophilin-dynamin complex promotes budding of clathrin-coated vesicles during synaptic vesicle recycling

Clathrin-mediated vesicle recycling in synapses is maintained by a unique set of endocytic proteins and interactions. We show that endophilin localizes in the vesicle pool at rest and in spirals at the necks of clathrin-coated pits (CCPs) during activity in lamprey synapses. Endophilin and dynamin colocalize at the base of the clathrin coat. Protein spirals composed of these proteins on lipid tubes in vitro have a pitch similar to the one observed at necks of CCPs in living synapses, and lipid tubules are thinner than those formed by dynamin alone. Tubulation efficiency and the amount of dynamin recruited to lipid tubes are dramatically increased in the presence of endophilin. Blocking the interactions of the endophilin SH3 domain in situ reduces dynamin accumulation at the neck and prevents the formation of elongated necks observed in the presence of GTPγS. Therefore, endophilin recruits dynamin to a restricted part of the CCP neck, forming a complex, which promotes budding of new synaptic vesicles.

Intersectin is a negative regulator of dynamin recruitment to the synaptic endocytic zone in the central synapse

Intersectin is a multidomain dynamin-binding protein implicated in numerous functions in the nervous system, including synapse formation and endocytosis. Here, we demonstrate that during neurotransmitter release in the central synapse, intersectin, like its binding partner dynamin, is redistributed from the synaptic vesicle pool to the periactive zone. Acute perturbation of the intersectin-dynamin interaction by microinjection of either intersectin antibodies or Src homology 3 (SH3) domains inhibited endocytosis at the fission step. Although the morphological effects induced by the different reagents were similar, antibody injections resulted in a dramatic increase in dynamin immunoreactivity around coated pits and at constricted necks, whereas synapses microinjected with the GST (glutathione S-transferase)-SH3C domain displayed reduced amounts of dynamin in the neck region. Our data suggest that intersectin controls the amount of dynamin released from the synaptic vesicle cluster to the periactive zone and that it may regulate fission of clathrin-coated intermediates.

Differential efficiency of the endocytic machinery in tonic and phasic synapses

Efficient synaptic vesicle membrane recycling is one of the key factors required to sustain neurotransmission. We investigated potential differences in the compensatory endocytic machineries in two glutamatergic synapses with phasic and tonic patterns of activity in the lamprey spinal cord. Post-embedding immunocytochemistry demonstrated that proteins involved in synaptic vesicle recycling, including dynamin, intersectin, and synapsin, occur at higher levels (labeling per vesicle) in tonic dorsal column synapses than in phasic reticulospinal synapses. Synaptic vesicle protein 2 occurred at similar levels in the two types of synapse. After challenging the synapses with high potassium stimulation for 30 min the vesicle pool in the tonic synapse was maintained at a normal level, while that in the phasic synapse was partly depleted along with expansion of the plasma membrane and accumulation of clathrin-coated intermediates at the periactive zone. Thus, our results indicate that an increased efficiency of the endocytic machinery in a synapse may be one of the factors underlying the ability to sustain neurotransmission at high rates.

Amphiphysin is a component of clathrin coats formed during synaptic vesicle recycling at the lamprey giant synapse

Amphiphysin is a protein enriched at mammalian synapses thought to function as a clathrin accessory factor in synaptic vesicle endocytosis. Here we examine the involvement of amphiphysin in synaptic vesicle recycling at the giant synapse in the lamprey. We show that amphiphysin resides in the synaptic vesicle cluster at rest and relocates to sites of endocytosis during synaptic activity. It accumulates at coated pits where its SH3 domain, but not its central clathrin/AP-2-binding (CLAP) region, is accessible for antibody binding. Microinjection of antibodies specifically directed against the CLAP region inhibited recycling of synaptic vesicles and caused accumulation of clathrin-coated intermediates with distorted morphology, including flat patches of coated presynaptic membrane. Our data provide evidence for an activity-dependent redistribution of amphiphysin in intact nerve terminals and show that amphiphysin is a component of presynaptic clathrin-coated intermediates formed during synaptic vesicle recycling.

A pre-embedding immunogold approach for detection of synaptic endocytic proteins in situ

During the past decade, many molecular components of clathrin-mediated endocytosis have been identified and proposed to play various hypothetical roles in the process [Nat. Rev. Neurosci. 1 (2000) 161; Nature 422 (2003) 37]. One limitation to the evaluation of these hypotheses is the efficiency and resolution of immunolocalization protocols currently in use. In order to facilitate the evaluation of these hypotheses and to understand more fully the molecular mechanisms of clathrin-mediated endocytosis, we have developed a protocol allowing enhanced and reliable subcellular immunolocalization of proteins in synaptic endocytic zones in situ. Synapses established by giant reticulospinal axons in lamprey are used as a model system for these experiments. These axons are unbranched and reach up to 80-100 microm in diameter. Synaptic active zones and surrounding endocytic zones are established on the surface of the axonal cylinder. To provide access for antibodies to the sites of synaptic vesicle recycling, axons are lightly fixed and cut along their longitudinal axis. To preserve the ultrastructure of the synaptic endocytic zone, antibodies are applied without the addition of detergents. Opened axons are incubated with primary antibodies, which are detected with secondary antibodies conjugated to gold particles. Specimens are then post-fixed and processed for electron microscopy. This approach allows preservation of the ultrastructure of the endocytic sites during immunolabeling procedures, while simultaneously achieving reliable immunogold detection of proteins on endocytic intermediates. To explore the utility of this approach, we have investigated the localization of a GTPase, dynamin, on clathrin-coated intermediates in the endocytic zone of the lamprey giant synapse. Using the present immunogold protocol, we confirm the presence of dynamin on late stage coated pits [Nature 422 (2003) 37] and also demonstrate that dynamin is recruited to the coat of endocytic intermediates from the very early stages of the clathrin coat formation. Thus, our experiments show that the current pre-embedding immunogold method is a useful experimental tool to study the molecular mechanisms of synaptic vesicle recycling.

Colocalization of synapsin and actin during synaptic vesicle recycling

It has been hypothesized that in the mature nerve terminal, interactions between synapsin and actin regulate the clustering of synaptic vesicles and the availability of vesicles for release during synaptic activity. Here, we have used immunogold electron microscopy to examine the subcellular localization of actin and synapsin in the giant synapse in lamprey at different states of synaptic activity. In agreement with earlier observations, in synapses at rest, synapsin immunoreactivity was preferentially localized to a portion of the vesicle cluster distal to the active zone. During synaptic activity, however, synapsin was detected in the pool of vesicles proximal to the active zone. In addition, actin and synapsin were found colocalized in a dynamic filamentous cytomatrix at the sites of synaptic vesicle recycling, endocytic zones. Synapsin immunolabeling was not associated with clathrin-coated intermediates but was found on vesicles that appeared to be recycling back to the cluster. Disruption of synapsin function by microinjection of antisynapsin antibodies resulted in a prominent reduction of the cytomatrix at endocytic zones of active synapses. Our data suggest that in addition to its known function in clustering of vesicles in the reserve pool, synapsin migrates from the synaptic vesicle cluster and participates in the organization of the actin-rich cytomatrix in the endocytic zone during synaptic activity.

Les mécanismes synaptiques et intrinsèques qui sous-tendent l’activité des cellules réticulospinales (RS) en réponse à une stimulation sensorielle de type cutané chez la lamproie

Chez diverses espèces animales, les informations sensorielles peuvent déclencher la locomotion. Ceci nécessite l’intégration des informations sensorielles par le système nerveux central. Chez la lamproie, les réseaux locomoteurs spinaux sont activés et contrôlés par les cellules réticulospinales (RS), système descendant le plus important. Ces cellules reçoivent des informations variées provenant notamment de la périphérie. Une fois activées par une brève stimulation cutanée d’intensité suffisante, les cellules RS produisent des dépolarisations soutenues de durées variées impliquant des propriétés intrinsèques calcium-dépendantes et associées à l’induction de la nage de fuite. Au cours de ce doctorat, nous avons voulu savoir si les afférences synaptiques ont une influence sur la durée des dépolarisations soutenues et si l’ensemble des cellules RS partagent des propriétés d’intégration similaires, impliquant possiblement les réserves de calcium internes. Dans un premier temps, nous montrons pour la première fois qu’en plus de dépendre des propriétés intrinsèques des cellules réticulospinales, les dépolarisations soutenues dépendent des afférences excitatrices glutamatergiques, incluant les afférences spinales, pour perdurer pendant de longues périodes de temps. Les afférences cutanées ne participent pas au maintien des dépolarisations soutenues et les afférences inhibitrices glycinergique et GABAergiques ne sont pas suffisantes pour les arrêter. Dans un deuxième temps, nous montrons que suite à une stimulation cutanée, l’ensemble des cellules RS localisées dans les quatre noyaux réticulés possèdent un patron d’activation similaire et elles peuvent toutes produire des dépolarisations soutenues dont le maintien ne dépend pas des réserves de calcium internes. Enfin, les résultats obtenus durant ce doctorat ont permis de mieux comprendre les mécanismes cellulaires par lesquels l’ensemble des cellules RS intègrent une brève information sensorielle et la transforment en une réponse soutenue associée à une commande motrice.

Organisation et modulation du réseau neuronal de la respiration chez la lamproie.

Les mécanismes neuronaux contrôlant la respiration sont présentement explorés à l’aide de plusieurs modèles animaux incluant le rat et la grenouille. Nous avons utilisé la lamproie comme modèle animal nous permettant de caractériser les réseaux de neurones du tronc cérébral qui génèrent et modulent le rythme respiratoire. Nous avons d’abord caractérisé une nouvelle population de neurones, dans le groupe respiratoire paratrigéminal (pTRG), une région du tronc cérébral essentielle à la genèse du rythme respiratoire chez la lamproie. Les neurones de cette région sont actifs en phase avec le rythme respiratoire. Nous avons montré que ces neurones possèdent une arborisation axonale complexe, incluant des projections bilatérales vers les groupes de motoneurones du tronc cérébral qui activent les branchies ainsi que des connexions reliant les pTRG de chaque côté du tronc cérébral. Ces résultats montrent que le pTRG contient un groupe de cellules qui active les motoneurones respiratoires des deux côtés et qui pourrait être impliqué dans la synchronisation bilatérale du rythme respiratoire. Nous avons ensuite étudié les mécanismes neuronaux par lesquels le rythme respiratoire est augmenté en lien avec l’effort physique. Nous avons montré que la région locomotrice du mésencéphale (MLR), en plus de son rôle dans la locomotion, active les centres respiratoires pendant la nage, et même en anticipation. Les neurones de la MLR projetant vers les centres locomoteurs et respiratoires sont ségrégés anatomiquement, les neurones localisés plus dorsalement étant ceux qui possèdent des projections vers les centres respiratoires. Nous avons aboli la contribution de la partie dorsale de la MLR aux changements respiratoires en injectant des bloqueurs des récepteurs glutamatergiques localement, sur des préparations semi-intactes. Nous avons montré que lors d’épisodes de nage, une majeure partie de l’effet respiratoire est abolie par ces injections, suggérant un rôle prépondérant des neurones de cette région dans l’augmentation respiratoire pendant la locomotion. Nos résultats confirment que le rythme respiratoire est généré par une région rostrolatérale du pons de la lamproie et montrent que des connexions des centres locomoteurs arrivent directement à cette région et pourraient être impliquées dans l’augmentation respiratoire reliée à l’effort physique.

Molecular organization of 5S rDNA in sharks of the genus Rhizoprionodon: insights into the evolutionary dynamics of 5S rDNA in vertebrate genomes

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)