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Recent event-related potential studies report a P600 effect to incongruous verbs preceded by semantically associated inanimate noun-phrase (NP) arguments, e.g., "eat" in "At breakfast the eggs would eat...". This P600 effect may reflect the processing cost incurred when semantic-thematic relationships between critical verbs and their preceding NP argument(s) bias towards different interpretations to those dictated by their sentences' syntactic structures. We have termed such violations of alternative thematic roles, "thematic role violations." Semantic-thematic relationships are influenced both by semantic associations and by more basic semantic features, such as a noun's animacy. This study determined whether a P600 effect can be evoked by verbs whose thematic structures are violated by their preceding inanimate NP arguments, even in the absence of close semantic-associative relationships with these arguments or their preceding contexts. ERPs were measured to verbs under four conditions: (1) non-violated ("At breakfast the boys would eat..."); (2) preceded by introductory clauses and animate NPs that violated their pragmatic expectations but not their thematic structures ("At breakfast the boys would plant..."); (3) preceded by semantically related contexts but inanimate NPs that violated their thematic structures ("At breakfast the eggs would eat..."); (4) preceded by semantically unrelated contexts and inanimate NPs that also violated their thematic structures ("At breakfast the eggs would plant..."). Pragmatically non-thematic role violated verbs preceded by unrelated contexts and animate NPs evoked robust N400 effects and small P600 effects. Thematically violated verbs preceded by inanimate argument NPs evoked robust P600 effects but no N400 effects, regardless of whether these inanimate arguments or their preceding contexts were semantically related or unrelated to these verbs. These findings suggest that semantic-thematic relations, related to animacy constraints on verbs' arguments, are computed online and can immediately impact verb processing within active, English sentences.

Event-related potentials were measured as subjects read sentences presented word by word. A small N400 and a robust P600 effect were elicited by verbs that assigned the thematic role of Agent to their preceding noun-phrase argument when this argument was inanimate in nature. The amplitude of the P600, but not the N400, was modulated by the transitivity of the critical verbs and by plausibility ratings of passivised versions of these sentences (reflecting the fit between the critical verb and the inanimate noun-phrase as the verb's Theme). The P600 was similar in scalp distribution although smaller in amplitude, than that elicited by verbs with morphosyntactic violations. Pragmatically unlikely verbs that did not violate thematic constraints elicited a larger N400 but no P600 effect. These findings support the theory that the cost of syntactic processing on a verb is influenced by the precise thematic relationships between that verb and its preceding arguments. (Contains 20 footnotes, 11 tables, and 5 figures.)

The taxonomic position and phylogenetic affinities of the endemic North Asian genus Kolhymamnicola Starobogatov and Budnikova, 1976 (Gastropoda: Amnicolidae) remain unknown. To resolve this, we studied key morpho-anatomical characteristics of Kolhymamnicola snails and performed a molecular phylogenetic analysis based on sequences of COI mtDNA, 16S rRNA, and 18S rRNA genes. In terms of protoconch microsculpture, operculum, radular teeth, and gill complex morphology, Kolhymamnicola snails do not differ significantly from the North American genera Amnicola Gould and Haldeman, 1840 and Taylorconcha Hershler et al., 1994, and the European genus Marstoniopsis van Regteren Altena 1936. The bifid penis found in Kolhymamnicola is similar to that in the genus Marstoniopsis. The female reproductive anatomy has some features shared by Kolhymamnicola and Taylorconcha (absence of bursa copulatrix, single seminal receptacle in rs2′ position, and ventral channel). The molecular analysis has revealed Taylorconcha as the closest relative to Kolhymamnicola; the COI-based genetic distance between them amounted to 0.113. We discuss the possible time of divergence of these two genera, as well as of European Marstoniopsis and the Baikal Lake endemic family Baicaliidae. The last common ancestor of these groups was widely distributed in Miocene–Pliocene in the Holarctic waterbodies. Recent Kolhymamnicola snails are distributed in Northern Asia, including lakes of the Baikal rift zone. We rank the Baicaliidae as a family rather than a subfamily of Amnicolidae based on their distinct, unique morpho-anatomical characteristics and highly supported separate position on the molecular tree. The tribe Erhaiini Davis and Kuo, 1985 is elevated to the rank of the family, with 3–4 recent genera included. The family Palaeobaicaliidae Sitnikova et Vinarski fam. nov. is established to embrace the Cretaceous North Asian gastropods conchologically similar to the recent Baicaliidae and Pyrgulidae. [ABSTRACT FROM AUTHOR]

Origins of impaired adaptive functioning in schizophrenia remain poorly understood. Behavioral disorganization may arise from an abnormal reliance on common combinations between concepts stored in semantic memory. Avolition-apathy may be related to deficits in using goal-related requirements to flexibly plan behavior. The authors recorded event-related potentials (ERPs) in 16 patients with medicated schizophrenia and 16 healthy controls in a novel video paradigm presenting congruous or incongruous objects in real-world activities. All incongruous objects were contextually inappropriate, but the incongruous scenes varied in comprehensibility. Psychopathology was assessed with the Scales for the Assessment of Positive and Negative Symptoms (SAPS/SANS) and the Brief Psychiatric Rating Scale. In patients, an N400 ERP, thought to index activity in semantic memory, was abnormally enhanced to less comprehensible incongruous scenes, and larger N400 priming was associated with disorganization severity. A P600 ERP, which may index flexible object-action integration based on goal-related requirements, was abnormally attenuated in patients, and its smaller magnitude was associated with the SANS rating of impersistence at work or school (goal-directed behavior). Thus, distinct neurocognitive abnormalities may underlie disorganization and goal-directed behavior deficits in schizophrenia. Keywords: schizophrenia, ERPs, real-world knowledge, comprehension of goal-directed actions, behavior abnormalities

This article aims to reconstruct the invasion of the ear-shaped pond snail, Radix auricularia (Linnaeus, 1758), to Lake Baikal, East Siberia. This species is widely distributed in the Palaearctic and Northern America, and since the early 20th century has formed abundant and sustained populations in Lake Baikal. The data provided on the morphological and genetic variability of R. auricularia help to better describe and delineate the species. With an integrative approach involving morphological and molecular data, we improved the knowledge of the intraspecific variability of R. auricularia in the most important characteristics used for its determination. Molecular sequences of nuclear spacer fragment ITS-2 and mitochondrial gene fragment cyt–b were obtained from 32 individuals of Radix (including seven outgroup Radix species) collected from various parts of Lake Baikal and adjacent waterbodies and compared with sequences of 32 individuals of R. auricularia from different regions of the Palaearctic as well as with individuals determinated as R. intercisa from Lake Baikal, R. iturupica from the Kurile Islands, R. ussuriensis from the Khabarovsk region, R. narzykulovi from Tajikistan, and R. schubinae from the Amur region. Molecular genetic analyses revealed that all specimens collected from Lake Baikal belong to R. auricularia. There are no genetically distinct groups of snails that would correspond to two morphospecies previously recorded in Lake Baikal (e.g., R. auricularia s. str. and R. intercisa). Variability of the characteristics that are commonly used for species identification (shell morphology, mantle pigmentation, shape and position of the bursa copulatrix, length and position of the bursa duct, length ratio of preputium to penial sheath) were found in individuals analysed with molecular genetics to be broader than recognised in the current literature. Some shells of R. auricularia collected from Lake Baikal resemble shells of another lymnaeid species, R. balthica, and without molecular assessment can be confused with the latter. Geometric morphometric analysis of more than 250 shells revealed no observed hiatus between Baikalian and non-Baikalian R. auricularia. The probable stages and pathways of R. auricularia invasion to Lake Baikal's ecosystem are outlined and discussed. Factors such as global climate warming and human activity stimulated and facilitated the ongoing dispersal of ear pond snails within Lake Baikal. [ABSTRACT FROM AUTHOR]

Event-related potentials to critical verbs were measured as patients with schizophrenia and healthy controls read sentences word by word. Relative to their preceding context, critical verbs were (a) congruous, (b) incongruous and semantically unrelated to individual preceding words (pragmaticsemantic violations), (c) incongruous but semantically related to individual preceding words (animacy-semantic violations), or (d) syntactically anomalous. The N400 was modulated normally in patients, suggesting that semantic integration between individual words within sentences was normal in schizophrenia. The amplitude of the P600 to both syntactic and animacy-semantic violations was reduced in patients relative to controls. The authors suggest that, in schizophrenia, an abnormality in combining semantic and syntactic information online to build up propositional meaning leaves sentence processing to be primarily driven by semantic relationships between individual words. Keywords: language, schizophrenia, N400 event-related potential, semantics, syntax

We describe a new species, Kobeltocochlea tamarae Sitnikova, Teterina & Maximova sp. nov., from Lake Baikal discovered in the Saint Petersburg methane seep at a depth of approximately 1400 m. The uncorrected genetic distance was 4.26% of the COI gene between this new species and K. falsipumyla collected from the Academic Ridge at depths between 157 and 163 m. The two shallow‐water species, K. martensiana and K. olchonensis, differed in substrate preference and geographic habitats, with a genetic distance of 0.97% for COI. Phylogenetic analysis of mitochondrial (COI, 16S) and nuclear (ITSI, 28S) sequences indicated that Kobeltocochlea was paraphyletic with respect to other benedictiid genera Benedictia and Yaroslawiella, formed well‐supported monophyletic groups. We revealed the discordance of morphological and genetic data within Kobeltocochlea and other benedictiids, which reflected their complicated history. The current knowledge of benedictiids does not allow for significant changes in the taxonomy of the Benedictiidae, except for synonymizing K. lindholmiana with K. olchonensis and Pseudobenedictia with Benedictia that were also investigated. We speculate that three main lineages of benedictiids originated from three populations of a single ancient species approximately 3.2 Ma. The speciation of deep‐water species was probably driven independently by bathymetric isolation in the cold methane seeps of different geomorphological structures. The diversification of the third lineage consisting of littoral (including K. martensiana/K. olchonensis), deep‐water, and eurybathic benedictiids may be explained by rapid adaptive radiation to intralacustrine environments. [ABSTRACT FROM AUTHOR]

Background: Transcranial photobiomodulation (tPBM) has recently emerged as a potential cognitive enhancement technique and clinical treatment for various neuropsychiatric and neurodegenerative disorders by delivering invisible near-infrared light to the scalp and increasing energy metabolism in the brain.Objective: We assessed whether transcranial photobiomodulation with near-infrared light modulates cerebral electrical activity through electroencephalogram (EEG) and cerebral blood flow (CBF).Methods: We conducted a single-blind, sham-controlled pilot study to test the effect of continuous (c-tPBM), pulse (p-tPBM), and sham (s-tPBM) transcranial photobiomodulation on EEG oscillations and CBF using diffuse correlation spectroscopy (DCS) in a sample of ten healthy subjects [6F/4 M; mean age 28.6±12.9 years]. c-tPBM near-infrared radiation (NIR) (830 nm; 54.8 mW/cm2; 65.8 J/cm2; 2.3 kJ) and p-tPBM (830 nm; 10 Hz; 54.8 mW/cm2; 33%; 21.7 J/cm2; 0.8 kJ) were delivered concurrently to the frontal areas by four LED clusters. EEG and DCS recordings were performed weekly before, during, and after each tPBM session.Results: c-tPBM significantly boosted gamma (t = 3.02, df = 7, p < 0.02) and beta (t = 2.91, df = 7, p < 0.03) EEG spectral powers in eyes-open recordings and gamma power (t = 3.61, df = 6, p < 0.015) in eyes-closed recordings, with a widespread increase over frontal-central scalp regions. There was no significant effect of tPBM on CBF compared to sham.Conclusion: Our data suggest a dose-dependent effect of tPBM with NIR on cerebral gamma and beta neuronal activity. Altogether, our findings support the neuromodulatory effect of transcranial NIR. [ABSTRACT FROM AUTHOR]

Background: Hypertension poses an increased risk of Alzheimer's disease (AD). Coronavirus disease 2019 (COVID‐19) may exacerbate this risk by affecting the Renin‐Angiotensin system (RAS), which contributes to the regulation of neurovascular coupling (NVC). NVC is a mechanism that optimizes cerebral blood flow (CBF) to meet the metabolic and waste‐removal needs of the brain. Disrupted NVC may predispose individuals to AD through hypoxia‐related protein changes and suboptimal protein‐waste removal from the brain. Several studies reported reduced CBF in long‐haul COVID‐19 patients. Among antihypertensive medicines that target the RAS, angiotensin receptor blockers (ARBs), but not angiotensin‐converting enzyme inhibitors (ACEIs), were previously found to regulate CBF. Therefore, we hypothesized that, if taken during and after a COVID‐19 episode, ARBs rather than ACEIs would be protective against long‐term CBF dysregulation. Method: We quantified NVC through a novel analysis paradigm that takes advantage of simultaneous resting‐state electroencephalography (EEG) and functional magnetic resonance imaging (fMRI). We obtained scans from older adult participants (aged 55‐80), including healthy controls and hypertensive COVID‐19 survivors medicated with ARBs or ACEIs during their COVID‐19 infection (occurring 3‐27 months before scanning). Hidden Markov modeling on source‐localized EEG was used to detect transient electrophysiological activity in distinct neural networks. A rapid event‐related fMRI analysis deconvolved the blood oxygenation level‐dependent (BOLD) changes evoked by the network‐specific electrophysiological activations. NVC was measured as the slope of vascular BOLD changes over the time‐locked electrophysiological neural changes. Result: In this pilot study, the default mode network (DMN) showed differences in NVC between the hypertensive COVID‐19 survivors and the healthy control group. Crucially, the ARB‐medicated subgroup, like the control group, showed the BOLD response in the DMN regions time‐locked to the DMN electrophysiological activations; NVC differences between the ARB‐medicated and control groups did not reach significance. In contrast, the ACEI‐medicated subgroup showed a reduced NVC in the DMN relative to the control group. Conclusion: The DMN, which is linked to memory dysfunction in AD, may be vulnerable to NVC disruptions, given its high metabolic demands. Hypertension management with ARBs may reduce COVID‐19's effects on cerebrovascular regulation, preventing ischemic stroke, vascular dementia, and AD. Results replication is warranted. [ABSTRACT FROM AUTHOR]

The preparation and studies of a series of polybetaines ([PB.sub.n]) having cationic and anionic units covalently linked by short -[(C[H.sub.2]).sub.n]- spacer is reported. The results revealed that the length of the -[(C[H.sub.2]).sub.n]- spacer in betaine units have a significant effect on the ability of polybetaines to interact with anionic liposomes and to induce structural rearrangement within the liposomal membrane.

A new species of the family Planorbidae is described from the land thermal spring Khakusy, on the northeastern shore of Lake Baikal. The description of Gyraulus takhteevi sp. n. includes morphological characters and gene sequences (COI of mtDNA) for the species separation from sister taxon Gyraulus acronicus (A. Férussac, 1807) collected from the small Krestovka River in-flowing into the south-western part of the Lake. The new species differs from G. acronicus in small shell size of adults, having smaller number of prostate folds (maximal up to 26 in G. takhteevi n. sp. vs. 40 in G. acronicus), a short preputium (approximately twice shorter than the phallotheca), and an elongated bursa copulatrix. The population of Gyraulus takhteevi sp. n. consists of two co-existent morphs: one of them has a narrow shell spire and the second is characterized by wide spire similar to the shell of G. acronicus. One of the two revealed haplotypes of the new species includes both morphs, while the second consists of snails with wide spired shells. [ABSTRACT FROM AUTHOR]

With 104 endemic species family Candonidae is one of the most diverse crustacean groups in Lake Baikal, yet their phylogenetic relationships and position in the family have not been addressed so far. Here, we study the phylogenetic position of Baikal candonids within the family and their evolutionary history using molecular markers for the first time since their original description. We choose 10 Baikal and 28 species from around the world, and three ribosomal RNA-s (18S, 28S, and 16S), and analyze individual and concatenated datasets using Bayesian Inference in MrBayes and BEAST. For molecular divergence time estimates, four fossil records are used to calibrate the root and three internal nodes. The 28S dataset is tested under the strict molecular clock, while for other data we use relaxed clocks. Resulting trees show incongruence between molecular and fossil divergence time estimates, with the former suggesting older ages. Strict molecular clock analysis results in narrower node age confidence intervals and younger time estimates than other analysis. All trees support at least two candonid lineages in Baikal, with two independent colonization events, and 28S suggests a major radiation between 12 and 5 Mya. This divergence time estimate mostly agrees with another, unrelated, ostracod group in the lake and other lake animals as well. Baikal candonid clades show a close phylogenetic relationship with Palearctic lineages, but their deep divergence is indicative of separate genera. Results also suggest a monophyly of tribes that today live exclusively in subterranean waters, and we offer several hypotheses of their evolutionary history. [ABSTRACT FROM AUTHOR]

Uncoupling between molecular and morphological evolution is common in many animal and plant lineages. This is especially frequent among groups living in ancient deep lakes, because these ecosystems promote rapid morphological diversification, and has already been demonstrated for Tanganyika cychlid fishes and Baikal amphipods. Ostracods are also very diverse in these ecosystems, with 107 candonid species described so far from Baikal, majority of them in the genera Candona Baird, 1845 and Pseudocandona Kaufmann, 1900. Here we study their morphological and molecular diversity based on four genes (two nuclear and two mitochondrial), 10 species from the lake, and 28 other species from around the world. The results of our phylogenetic analysis based on a concatenated data set, along with sequence diversity, support only two genetic lineages in the lake and indicate that a majority of the Baikal Candona and Pseudocandona species should be excluded from these genera. We describe a new genus, Mazepovacandona gen. n., to include five Baikal species, all redescribed here. We also amend the diagnosis for the endemic genus Baicalocandona Mazepova, 1972 and redescribe two species. Our study confirms an exceptional morphological diversity of Lake Baikal candonids and shows that both Baikal lineages are closely related to Candona, but only distantly to Pseudocandona. [ABSTRACT FROM AUTHOR]

A new gastropod species, Pseudobaikalia michelae Sitnikoiva & Kovalenkova, sp. n., (family Baicaliidae) is described from Lake Baikal. This is the first new species from the Baicaliidae for forty years. The new species is distinguished from its sister taxa by means of comparative morphology as well as analyses of DNA sequences (mtDNA and an intron of alpha-subunit gene of ATP-synthase). It was found in the southern and central-eastern parts of the lake where it occurs sympatrically with three other baicaliid species. Characters of the female reproductive system (i.e., a long oviduct loop with 2-3 narrow tube-like evaginations) and the aperture (i.e., oval shape with a simple outer lip) place these snails in the genus Pseudobaikalia Lindholm, 1909. The new species is most similar in its shell morphology to the northern Baikal species P. jentteriana (smooth elongated shape) but differs by a more oval aperture that is slightly angled to the columella. Combined mitochondrial and nuclear sequences in a Bayesian analysis showed that all specimens of P. michelae sp. n. form a well-supported clade. [ABSTRACT FROM AUTHOR]

Jelly-like microbial mat samples were collected from benthic surfaces at the St. Petersburg methane seep located in Central Baikal. The concentrations of certain ions, specifically chloride, bromide, sulphate, acetate, iron, calcium, and magnesium, were 2–40 times higher in the microbial mats than those in the pore and bottom water. A large number of diatom valves, cyanobacteria, and filamentous, rod-shaped and coccal microorganisms were found in the samples of bacterial mats using light, epifluorescence and scanning microscopy.Comparative analysis of a 16S rRNA gene fragment demonstrated the presence of bacteria and archaea belonging to the following classes and phyla: Betaproteobacteria, Gammaproteobacteria, Deltaproteobacteria, Verrucomicrobia, Cytophaga-Flavobacteria-Bacteroidetes, Cyanobacteria, and Euryarchaeota. The chemical composition and phylogenetic structure of the microbial community showed that the life activity of the mat occurs due to methane and its derivatives involved. Values of δ13C for the microbial mats varied from −73.6‰ to −65.8‰ and for animals from −68.9‰ to −36.6‰. Functional genes of the sequential methane oxidation (pmoAandmxaF) and different species of methanotrophic bacteria inhabiting cold ecosystems were recorded in the total DNA. Like in other psychroactive communities, the destruction of organic substances forming formed as a result of methanotrophy, terminates at the stage of acetate formation in the microbial mats of Lake Baikal (1,400 m depth). Its further transformation is limited by hydrogen content and carried out in the subsurface layers of sediments. [ABSTRACT FROM PUBLISHER]

The aim of this study was to gain further insights into how the brain distinguishes between meaning and syntax during language comprehension. Participants read and made plausibility judgments on sentences that were plausible, morphosyntactically anomalous, or pragmatically anomalous. In an event-related potential (ERP) experiment, morphosyntactic and pragmatic violations elicited significant P600 and N400 effects, respectively, replicating previous ERP studies that have established qualitative differences in processing conceptually and syntactic anomalies. Our main focus was a functional magnetic resonance imaging (fMRI) study in which the same subjects read the same sentences presented in the same pseudorandomized sequence while performing the same task as in the ERP experiment. Rapid-presentation event-related fMRI methods allowed us to estimate the hemodynamic response at successive temporal windows as the sentences unfolded word by word, without assumptions about the shape of the underlying response function. Relative to nonviolated sentences, the pragmatic anomalies were associated with an increased hemodynamic response in left temporal and inferior frontal regions and a decreased response in the right medial parietal cortex. Relative to nonviolated sentences, the morphosyntactic anomalies were associated with an increased response in bilateral medial and lateral parietal regions and a decreased response in left temporal and inferior frontal regions. Thus, overlapping neural networks were modulated in opposite directions to the two types of anomaly. These fMRI findings document both qualitative and quantitative differences in how the brain distinguishes between these two types of anomalies. This suggests that morphosyntactic and pragmatic information can be processed in different ways but by the same neural systems. [ABSTRACT FROM AUTHOR]

Event-related potentials (ERPs) discriminate between contextually appropriate and inappropriate objects appearing in video film clips of common activities. Incongruent objects elicited a larger negative-going deflection, which was similar to the N400 component describe previously in association with words an static pictures and which has been argue to reflect the integration of semantic information into a mental representation of the preceeding context. The onset of this potential occurred shortly after object presentation, indicating that semantic integration is a rapid online component of real-world perception. In addition, the anomalies in movies evoked a large late positive potential at posterior regions, suggesting that in event perception, semantic incongruity may trigger cognitive processes other than those mediating pure semantic integration. [ABSTRACT FROM AUTHOR]

Deficits in language comprehension in schizophrenia were examined using event-related potentials (ERPs). Schizophrenic and healthy participants read sentences in which the first clause ended with a homograph, and the second clause started with a target word that was semantically related to the homograph's dominant meaning (e.g., 1. Diving was forbidden from the bridge because the river had rocks in it, or 2. The guests played bridge because the river had rocks in it.). Processing of the targets (e.g., "river") was expected to be primarily influenced by the preceding overall sentence context (congruent in 1: incongruent in 2) in healthy participants, but to be inappropriately affected by the dominant meaning of homographs (e.g., the "structure" meaning of "'bridge") in sentences like 2 in schizophrenic patients. The N400 ERP component that is known to be sensitive to contextual effects during language processing confirmed these predictions. This showed that language abnormalities in schizophrenia may be related to deficient processing of context-irrelevant semantic representations of words from the discourse. [ABSTRACT FROM AUTHOR]

Simple Summary: Lake Baikal is the deepest and oldest freshwater ecosystem in the world. Since more than half of the currently known species of aquatic organisms inhabiting Lake Baikal are endemic, it is called a natural laboratory for the study of species diversity and evolution. However, despite many years of research, the true biodiversity of the lake is clearly insufficiently studied. As before, the deep-water zones of the lake remain white spots: there is little information about small benthic organisms, especially sessile forms. Therefore, when, for the first time, during deep-sea trawls, fragments of packaging plastic were raised from the bottom of Lake Baikal, the main goal was to determine the diversity of aquatic organisms inhabiting it. Analysis of the standard fragment of the mitochondrial genome allowed the obtaining of the first nucleotide data for the endemic Baikal bryozoans Hislopia placoides, two new species of leeches (Rhynchobdellida, Piscicolidae) and an unknown representative of stramenopiles that is genetically equidistant from the fungi-like organisms, Oomycetes and Chromulinales (Chrysophyta). Nucleotide data of H. placoides indirectly confirmed the hypothesis of the partial origin of Baikal fauna from Tethys derivatives. Thus, the abyssal zone of Baikal is an inexhaustible source of information about biodiversity and the evolution of life on the planet. Lake Baikal is a natural laboratory for the study of species diversity and evolution, as a unique freshwater ecosystem meeting the all of the main criteria of the World Heritage Convention. However, despite many years of research, the true biodiversity of the lake is clearly insufficiently studied, especially that of deep-water benthic sessile organisms. For the first time, plastic waste was raised from depths of 110 to 190 m of Lake Baikal. The aim of this study was to examine the biological community inhabiting the plastic substrate using morphological and molecular genetic analysis. Fragments of plastic packaging materials were densely populated: bryozoans, leeches and their cocoons, capsules of gastropod eggs, and turbellaria cocoons were found. All the data obtained as a result of an analysis of the nucleotide sequences of the standard bar-coding fragment of the mitochondrial genome turned out to be unique. Our results demonstrate the prospects for conducting comprehensive studies of artificial substrates to determine the true biodiversity of benthos in the abyssal zone of Lake Baikal. [ABSTRACT FROM AUTHOR]

Background: Islands have traditionally been the centre of evolutionary biological research, but the dynamics of immigration and differentiation at continental islands have not been well studied. Therefore, we focused on the Japanese archipelago, the continental islands located at the eastern end of the Eurasian continent. While the Japanese archipelago is characterised by high biodiversity and rich freshwater habitats, the origin and formation mechanisms of its freshwater organisms are not clear. In order to clarify the history of the planorbid gastropod fauna, we conducted phylogenetic analysis, divergence time estimation, ancestral state reconstruction, and lineage diversity estimations. Results: Our analyses revealed the formation process of the planorbid fauna in the Japanese archipelago. Most lineages in the Japanese archipelago have closely related lineages on the continent, and the divergence within the Japanese lineages presumably occurred after the late Pliocene. In addition, each lineage is characterised by different phylogeographical patterns, suggesting that immigration routes from the continent to the Japanese archipelago differ among lineages. Furthermore, a regional lineage diversity plot showed that the present diversity in the Japanese archipelago potentially reflects the differentiation of lineages within the islands after the development of the Japanese archipelago. Conclusions: Although additional taxon sampling and genetic analysis focused on each lineage are needed, our results suggest that immigration from multiple routes just prior to the development of the Japanese archipelago and subsequent diversification within the islands are major causes of the present-day diversity of the Japanese planorbid fauna. [ABSTRACT FROM AUTHOR]