European River Lamprey Lampetra Fluviatilis Research Articles

The Molecular Mechanism of Body Axis Induction in Lampreys May Differ from That in Amphibians.

Lamprey homologues of the classic embryonic inducer Noggin are similar in expression pattern and functional properties to Noggin homologues of jawed vertebrates. All noggin genes of vertebrates apparently originated from a single ancestral gene as a result of genome duplications. nogginA, nogginB and nogginC of lampreys, like noggin1 and noggin2 of gnathostomes, demonstrate the ability to induce complete secondary axes with forebrain and eye structures when overexpressed in Xenopus laevis embryos. According to current views, this finding indicates the ability of lamprey Noggin proteins to suppress the activity of the BMP, Nodal/Activin and Wnt/beta-catenin signaling pathways, as shown for Noggin proteins of gnathostomes. In this work, by analogy with experiments in Xenopus embryos, we attempted to induce secondary axes in the European river lamprey Lampetra fluviatilis by injecting noggin mRNAs into lamprey eggs in vivo. Surprisingly, unlike what occurs in amphibians, secondary axis induction in the lampreys either by noggin mRNAs or by chordin and cerberus mRNAs, the inductive properties of which have been described, was not observed. Only wnt8a mRNA demonstrated the ability to induce secondary axes in the lampreys. Such results may indicate that the mechanism of axial specification in lampreys, which represent jawless vertebrates, may differ in detail from that in the jawed clade.

European River Lamprey Lampetrafluviatilis (Petromyzontidae) of the Pskov Lakeland: Current State of Isolated Populations

Small freshwater (resident) populations of the European river lamprey Lampetrafluviatilis from an isolated from the sea upper part of a river system with numerous lakes (the upper reaches of tributaries of the Daugava River and Lake Peipus, Pskov Oblast, Russia) have been studied. Adult individuals of the lamprey have been attributed to common and large size groups; adults are similar to other resident lamprey from the Baltic Sea basin. The presence of larvae of different size and age groups indicates regular spawning of the European river lamprey in the studied watersheds. Analysis of the modern and historical (before the isolation) distribution of lamprey revealed a reduction in habitats and a decrease in the number of individuals. Dam-associated disruption of migration routes led to the disappearance of anadromous form, and consequently, disappearance of resident lamprey from most of the studied waterbodies. We attribute the decrease in the number of rivers inhabited by lamprey and abundance of the lamprey both to anthropogenic factors (direct blocking of an access of anadromous form of the lamprey to spawning grounds by hydraulic construction) and to the characteristics of the studied area. The richness of the river system with lentic waterbodies makes it suitable for lamprey inhabitation with an influx of large anadromous individuals capable of crossing such reservoirs in search of spawning sites.

European River Lamprey Lampetra fluviatilis (Petromyzontidae) of the Pskov Lakeland: Current State of Isolated Populations

Small freshwater (resident) populations of the European river lamprey Lampetra fluviatilis from an isolated from the sea upper part of a river system with numerous lakes (the upper reaches of tributaries of the Daugava River and Lake Peipus, Pskov Oblast, Russia) have been studied. Adult individuals of the lamprey have been attributed to common and large size groups; adults are similar to other resident lamprey from the Baltic Sea basin. The presence of larvae of different size and age groups indicates regular spawning of the European river lamprey in the studied watersheds. Analysis of the modern and historical (before the isolation) distribution of lamprey revealed a reduction in habitats and a decrease in the number of individuals. Dam-associated disruption of migration routes led to the disappearance of anadromous form, and consequently, disappearance of resident lamprey from most of the studied waterbodies. We attribute the decrease in the number of rivers inhabited by lamprey and abundance of the lamprey both to anthropogenic factors (direct blocking of an access of anadromous form of the lamprey to spawning grounds by hydraulic construction) and to the characteristics of the studied area. The richness of the river system with lentic waterbodies makes it suitable for lamprey inhabitation with an influx of large anadromous individuals capable of crossing such reservoirs in search of spawning sites.

Sperm competition experiments reveal low prezygotic postmating isolation between parasitic and nonparasitic lamprey ecotypes.

The role of postmating sexual selection as a potential reproductive barrier in speciation is not well understood. Here, we studied the effects of sperm competition and cryptic female choice as putative postmating barriers in two lamprey ecotypes with a partial reproductive isolation. The European river lamprey Lampetra fluviatilis is anadromous and parasitic of other fish species, whereas the brook lamprey Lampetra planeri is freshwater resident and nonparasitic. We measured sperm traits in both ecotypes and designed sperm competition experiments to test the occurrence of cryptic female choice. We also performed sperm competition experiments either at equal semen volume or equal sperm number to investigate the role of sperm velocity on fertilization success. We observed distinct sperm traits between ecotypes with a higher sperm concentration and a lower sperm velocity for L. planeri compared with L. fluviatilis. The outcomes of sperm competition reflected these differences in sperm traits, and there was no evidence for cryptic female choice irrespective of female ecotype. At equal semen volume, L. planeri males had a higher fertilization success than L. fluviatilis and vice versa at equal sperm number. Our results demonstrate that different sperm traits between ecotypes can influence the male reproductive success and thus gene flow between L. planeri and L. fluviatilis. However, postmating prezygotic barriers are absent and thus cannot explain the partial reproductive isolation between ecotypes.

The First Analysis of Synaptonemal Complexes in Jawless Vertebrates: Chromosome Synapsis and Transcription Reactivation at Meiotic Prophase I in the Lamprey Lampetra fluviatilis (Petromyzontiformes, Cyclostomata)

Transcription is known to be substage-specific in meiotic prophase I. If transcription is reactivated in the mid pachytene stage in mammals when synapsis is completed, then this process is observed in the zygotene stage in insects. The process of transcriptional reactivation has been studied in a small number of different taxa of invertebrates and vertebrates. Here, for the first time, we investigate synapsis and transcription in prophase I in the European river lamprey Lampetra fluviatilis (Petromyzontiformes, Cyclostomata), which is representative of jawless vertebrates that diverged from the main branch of vertebrates between 535 and 462 million years ago. We found that not all chromosomes complete synapsis in telomeric regions. Rounded structures were detected in chromatin and in some synaptonemal complexes, but their nature could not be determined conclusively. An analysis of RNA polymerase II distribution led to the conclusion that transcriptional reactivation in lamprey prophase I is not associated with the completion of chromosome synapsis. Monomethylated histone H3K4 is localized in meiotic chromatin throughout prophase I, and this pattern has not been previously detected in animals. Thus, the findings made it possible to identify synaptic and epigenetic patterns specific to this group and to expand knowledge about chromatin epigenetics in prophase I.

No strict host specificity: Brain metacercariae Diplostomum petromyzifluviatilis Müller (Diesing, 1850) are conspecific with Diplostomum sp. Lineage 4 of Blasco-Costa et al. (2014).

Metacercariae of Diplostomum petromyzifluviatilis (Digenea, Diplostomidae) from the brain of European river lamprey Lampetra fluviatilis from the Baltic Sea basin and Arctic lamprey Lethenteron camtschaticum from the White Sea basin were studied with the use of genetic and morphological methods. Phylogenetic analysis based on cox1 marker showed that the parasites of both lamprey species were conspecific with Diplostomum sp. Lineage 4 of Blasco-Costa et al. (2014). The name Diplostomum petromyzifluviatilis Müller (Diesing, 1850) has historical precedence as a species described from the brain of lampreys and should be used in genus nomenclature. There were no morphological qualitative differences between the metacercariae from the two lamprey species but those from L. fluviatilis were larger than those from L. camtschaticum. We expanded the data on the second intermediate hosts and the localization of D. petromyzifluviatilis, showing that its metacercariae occur not only in the brain of lampreys but also in the brain and the retina of three-spined stickleback Gasterosteus aculeatus and the vitreous humour of the perch Perca fluviatilis across the European part of the Palearctic.

A SNP marker to discriminate the european brook lamprey (Lampetra planeri), river lamprey (L. fluviatilis) and their hybrids.

The European River lamprey Lampetra fluviatilis and the brook lamprey L. planeri are two closely related species that are also considered as partially reproductively isolated ecotypes. At the larval stage, they cannot be distinguished morphologically or genetically by mitochondrial DNA. We aimed at developing a molecular tool to identify early life stages of L. fluviatilis and L. planeri. We first identified Single Nucleotide Polymorphism (SNP) markers with distinct alleles between L. fluviatilis and L. planeri based on RADseq data from 186 individuals collected in France. Then, we developed a quantitative PCR protocol to genotype a species-specific SNP, which was tested on 270 samples including larvae and adults from both species and 17 sites from Western Europe. Results were consistent with morphological identification in all cases except for samples from the Rhône drainage and the Loch Lomond in Scotland. This marker allows the identification of larval stages of L. fluviatilis, L. planeri as well as hybrids. The two cases where the marker was not diagnostic might be explained by an isolated and distinct L. planeri lineage in the Rhône drainage, and high levels of admixture among L. fluviatilis, L. planeri and the lake-parasitic form in Loch Lomond.

A new element in the migration cycle of the European river lamprey Lampetra fluviatilis: downstream migration from a lake

A new element in the migration cycle of the European river lamprey Lampetra fluviatilis: downstream migration from a lake

Invasion of the European River Lamprey Lampetra fluviatilis in the Upper Volga

The European river lamprey came to the Upper Volga from the Baltic Sea most probably via a system of shipways developed in the 18th and 19th centuries. The Vyshnii Volochek, Tikhvin, and Mariinskaya water systems are possible invasion pathways for this species. Dispersal and colonization of the Caspian Basin was likely a combination of upstream and downstream migrations. Analysis of museum and our own samples showed that lamprey possibly migrated upstream (for spawning) along rivers of the Baltic Basin until they reached the watershed boundary from which they could disperse downstream (in the juvenile period) into rivers of the Caspian Basin. Dispersal in the Volga River could occur in accordance with the migration cycle of this opportunistic lamprey species and lead to the present distribution. Key features (dentition and number of trunk myomeres) showed that lamprey from the studied area are similar to lampreys from the Baltic basin, although specimens in each population have their own peculiarities in morphology (size and coloration). Genetic data (Cyt-b) support the idea of a relatively recent invasion of lamprey into the Upper Volga. The haplotype, found in three rivers, is one of the most widespread in Europe and is found along the supposed route of invasion.

Shedding light on the river and sea lamprey in western European marine waters

Lampreys are ancestral jawless vertebrates with particularly complex life histories. Population declines resulting from increased anthropogenic pressure have been observed. For semelparous diadromous lampreys, the marine phase remains largely a black box, making targeted management and conservation measures difficult to implement. Here, we collated a database of 168904 hauls from both fisheries-dependent and fisheries-independent surveys between 1965 and 2019. Lampreys were observed in only 254 hauls (<1% lamprey presence); 421 sea lamprey Petromyzon marinus and 300 European river lamprey Lampetra fluviatilis were identified. Sizes ranged from 13 to 92 cm and from 14 to 42 cm, respectively. The majority of lampreys (61%) were caught by mobile demersal gear types. The highest presence of both species was recorded within the Greater North Sea, followed by the Bay of Biscay. L. fluviatilis was observed closer to the coast than P. marinus. For both lampreys, there was an increase in size with distance from the coast. P. marinus were predominantly <60 cm and observed from August to February, indicating that these were sexually immature juveniles migrating out to sea. For L. fluviatilis, the majority were thought to be adults (>20 cm) and occurred in autumn, indicating inshore migration. Our observations provide insight into the ecology of lampreys at sea and highlight study locations and gear types, which may be more pertinent for future research. Greater awareness is needed during surveys to collate catch information on lampreys and improve understanding of their ecology and phenology at sea.

Comparative Analysis of Expression Patterns of the Noggin Gene Family Genes at the Early Development Stages of Head Structures in the European River Lamprey Lampetra fluviatilis

Comparative Analysis of Expression Patterns of the Noggin Gene Family Genes at the Early Development Stages of Head Structures in the European River Lamprey Lampetra fluviatilis

Речная минога Lampetra fluviatilis (L., 1758) (Petromyzontidae) как компонент донных ценозов Невской губы

The presence of larvae of the European river lamprey Lampetra fluviatilis was reported for the first time from in macrobenthic communities of the Neva Bay of the Gulf of Finland (St. Petersburg, Russia). It has been shown that ammocoetes inhabit several areas, at depths to 12 meters. Apart from ammocoetes, the communities with lamprey larvae contain abundant oligochaetes, bivalves, and less commonly chironomid larvae. At some sites, the number of larvae was up to 80 specimens/m2, while their biomass was over 90% of the total of the community. The abundance of macrozoobenthos in these sites is generally low (average abundance 190 specimens/m2, biomass – 70 g/m2), which is usual in autumn. Intestines of the ammocoetes constantly contained large quantities of diatoms representing common phytoplankton of the Gulf of Finland.

Речная минога Lampetra fluviatilis L. в Балтийском и Каспийском бассейнах Тверской области

Представлена дополненная информация о распространении и условиях обитания речной миноги (Lampetra fluviatilis L.) на территории Тверской области. Ареал на территории области представляет собой сочетание исторического (водотоки бассейна Балтийского моря) и инвазионного (водотоки бассейна Каспийского моря) компонентов. Обоснована идея вселения миноги в систему р. Волга по системам искусственных судоходных каналов. Состояние популяций в Каспийском бассейне указывает на продолжающийся процесс освоения новых местообитаний. Additional information on the distribution and habitat of the European river lamprey (Lampetra fluviatilis L.) in the Tver Region is presented. The areal of the European river lamprey in the Region consists of the historical (watercourses of the Baltic Sea Basin) and invasive (watercourses of the Caspian Sea Basin) components. The idea of the lamprey invasion in the Volga River through the system of manmade shipping canals is substantiated. The condition of the lamprey’s populations in the Caspian Sea Basin indicates the ongoing process of the species expansion.

Heterochrony of the Expression of Lanf and Foxg1 in the Lamprey Confirms the Appearance of the Telencephalon as an Evolutionarily Young Superstructure in the Central Nervous System of Vertebrates

One of the most important evolutionary innovations of vertebrates is a complexly structured telencephalon, which provides higher forms of nervous activity in animals and humans. This work is devoted to the study of the appearance of the telencephalon in the early stages of vertebrate evolution. At the same time, there is reason to believe that lampreys, due to their evolutionary antiquity, could retain some ancient expression patterns of genes that regulate the development of the brain in the very first vertebrates. The study of the features of spatio-temporal expression patterns of key genes that regulate the development of the forebrain in lampreys compared with other vertebrates can help to understand the molecular mechanisms underlying the appearance and evolutionary development of this unique structure of vertebrates. This paper presents the results from analyzing the gene-expression dynamics of Lanf, FoxG1, Otx2, Goosecoid, and HoxB9 in the early stages of development of the European river lamprey Lampetra fluviatilis. It was shown that lamprey genes involved in telencephalon differentiation (Lanf and FoxG1) exhibit heterochrony of expression compared with more evolutionarily advanced representatives of vertebrates. This fact confirms the idea that the telencephalon, being evolutionarily the youngest part of the brain, could appear in vertebrate ancestors as a superstructure in the late stages of their embryonic development.

Phylogeography of the European brook lamprey (Lampetra planeri) and the European river lamprey (Lampetra fluviatilis) species pair based on mitochondrial data.

The European river lamprey Lampetra fluviatilis and the European brook lamprey Lampetra planeri (Block 1784) are classified as a paired species, characterized by notably different life histories but morphological similarities. Previous work has further shown limited genetic differentiation between these two species at the mitochondrial DNA level. Here, we expand on this previous work, which focused on lamprey species from the Iberian Peninsula in the south and mainland Europe in the north, by sequencing three mitochondrial marker regions of Lampetra individuals from five river systems in Ireland and five in southern Italy. Our results corroborate the previously identified pattern of genetic diversity for the species pair. We also show significant genetic differentiation between Irish and mainland European lamprey populations, suggesting another ichthyogeographic district distinct from those previously defined. Finally, our results stress the importance of southern Italian L. planeri populations, which maintain several private alleles and notable genetic diversity.

The expression of FoxG1 in the early development of the European river lamprey Lampetra fluviatilis demonstrates significant heterochrony with that in other vertebrates

FoxG1, a member of the Fox/Forkhead family of winged helix transcription factors, plays key roles in the induction and spatial compartmentalization of the telencephalon in vertebrates. Loss- and gain-of-function experiments have established FoxG1 as a maintenance factor for neural progenitors and a crucial player in the specification of the ventral telencephalon (subpallium). For the first time in evolution, the telencephalon appeared in the ancestors of vertebrates, including cyclostomes. However, although FoxG1 homologues are present in cyclostomes (i.e., in lampreys and hagfishes), no systematic study of the spatial-temporal expression of FoxG1 during the embryonic development of these animals has been carried out. Given these findings, we have now studied FoxG1 spatial-temporal expression patterns in the early development of the European river lamprey Lampetra fluviatilis. We show that in contrast to other vertebrates, in which the expression of FoxG1 begins during neurulation, the expression of this gene in L. fluviatilis starts after neurulation, first at stage 21 (early head protrusion) in the area of the otic placodes and then, beginning from stage 22, in the telencephalon. Such heterochrony of FoxG1 expression in the lamprey may reflect the fact that in this basally divergent representative of vertebrates, telencephalon specification occurs relatively late. This heterochrony could be related to the evolutionary history of the telencephalon, with a recent appearance in vertebrates as an extension to more ancient anterior brain regions. Another peculiarity of FoxG1 expression in lamprey, compared to other vertebrates, is that it is not expressed in the lamprey optic structures.

Thermoadaptation Characteristics of European River Lamprey Lampetra fluviatilis Smolts

Thermoadaptation characteristics of smolts of European river lamprey Lampetra fluviatilis are studied in experimental conditions for the first time. The final preferred temperature in the smolts preliminary acclimated to water temperature of 9 is 15.3°С. The value of sublethal temperature determined by the method of critical thermal maximum at a 9°С/h temperature increase rate is 29.0°С, while that of the upper lethal temperature is 30.8°С. The values of the final selected and upper lethal temperatures in river lamprey smolts are close to those in salmonids and coregonids.

Experimental study of the European river lamprey Lampetra fluviatilis (L.) downstream migrating smolts rheoreaction under various illuminations

Rheoreaction of the downstream migrating smolts of the European river lamprey was studied in the experimental conditions at illuminations of day and night intensity. It was found that at the daytime the smolts are mostly dormant and if move downstream then in active-passive form (with the head against the stream, and their speed going beyond the velocity). This data is well within the findings on the night downstream migration of the smolts during the 24 h period in natural conditions. Thus, the downstream migration of the smolts has an active form.

Circadian rhythms and locomotor activity of smolts of the european river lamprey lampetra fluviatilis (l.)

Locomotor activity was investigated in smolts of the European river lamprey at alternation of light and darkness (12/12 h) and in the dark. Two groups of smolts were discerned differing in the level of locomotor activity. The presence of the circadian rhythm in smolts has been revealed, and its role in downstream migration has been shown. The locomotor activity leading smolts to channel flow increases with decreasing illumination at evening twilight. The period of high nocturnal activity is completed a short time before morning twilight, under the action of the individual circadian rhythm. This decreases the probability of impact of predators on migrating smolts.

Results of Hybridization between Anadromous and Resident Forms of European River Lamprey Lampetra fluviatilis

Survival of the progeny obtained from artificial crossing of large parasitic anadromous and small nonparasitic resident European river lampreys Lampetra fluviatilis is analyzed. A high individual survival (~61% on average) up to the stage of prolarvae burrowing into ground confirms the absence of a postzygotic barrier between the lamprey forms. The obtained results are discussed in the framework of two theories: of paired species and of intraspecies diversity.