Contribution of lactobacillus casei to the recovery from chemically induced skeletal muscle damage under chronic stress

Background: Regeneration of damaged skeletal muscle requires sufficient supply of nutrients. Fully functional intestine and colon assure sufficient supply of nutrients. Gut commensal bacteria are known to support intestinal function. Previously lactobacillus treatment of elite athletes was shown to be effective in attenuating fatigue and impaired performance. We hypothesized that Lactobacillus casei (L.casei) administration may facilitate recovery of damaged skeletal muscle when the gut function is suppressed under chronic stress in which muscle regeneration is compromised. Objective: To investigate contribution of L.casei under chronic stress to the recovery of damaged skeletal muscle in young and older adult mice. Methods: L.casei was given orally at a dose of 10-8 /day for 7days to 10 weeks old (young) and 45-55 weeks old (older adult) male C57BL/6J mice. Vehicle control mice received an equivalent volume of water for 7 days. On the eighth day, cardiotoxin (CTX) was injected to gatrocnemius muscle to induce muscle damage. Both groups were assigned 2 hours repeated-restraint stress everyday (chronic stress). On days 3, 5, 7, 10, 14 and 20 after CTX injection, mice were sacrificed. Excised gastrocnemius muscle was subjected to weight measurement and immunohistochemical analyses. Results: There were significant differences in both the recovery of muscle weight and the regeneration process of gastrocnemius muscle examined immunohistochemically between control and L.casei treated young and older adult groups. Especially, the expression of developmental MHC (dMHC), a marker of premature regeneration, was positive up to 3 days in older adult groups. The delay in the recovery of muscle weight was obvious in older adult mice regardless of the treatment. However, while the expression of dMHC was prolonged up to day 7 in the vehicle control, dMHC expression was notable only up to day 3 or day 5 in the L.casei treated. Therefore, in older adult mice L.casei treatment under chronic stress may have facilitated the maturation process of regenerating skeletal muscle. Conclusion: Our results suggests that L.casei favor under chronic stress favors the recovery of skeletal muscle from muscle damage. The maintenance of gut function by L. casei treatment may have facilitated the maturation process of regenerating skeletal muscle

Phylogeny and historical demography of endemic fishes in Lake Biwa: the ancient lake as a promoter of evolution and diversification of freshwater fishes in western Japan

To elucidate the origins of the endemic fish of Lake Biwa, an ancient lake in Japan, and the role of the lake in the diversification of freshwater fish in western Japan, we established a molecular phylogenetic framework with an absolute time scale and inferred the historical demography of a large set of fish species in and around the lake. We used mtDNA sequences obtained from a total of 190 specimens, including 11 endemic species of Lake Biwa and their related species, for phylogenetic analyses with divergence time estimations and from a total of 2319 specimens of 42 species (including 14 endemics) occurring in the lake for population genetic analyses. Phylogenetic analysis suggested that some of the endemic species diverged from their closest relatives earlier (1.3-13.0 Ma) than the period in which the present environmental characteristics of the lake started to develop (ca. 0.4 Ma), whereas others diverged more recently (after 0.4 Ma). In contrast, historical demographic parameters suggested that almost all species, including endemic and nonendemic ones, expanded their populations after the development of the present lake environment. In phylogeographic analyses, common or very close haplotypes of some species were obtained from Lake Biwa and other regions of western Japan. The phylogenetic and historical demographic evidence suggests that there was a time lag between phylogenetic divergence and population establishment and that phenotypic adaptation of some endemic species to the limnetic environment occurred much later than the divergences of those endemic lineages. Population structure and phylogeographic patterns suggest that Lake Biwa has functioned not only as the center of adaptive evolution but also as a reservoir for fish diversity in western Japan

A dataset of fishes in and around Inle Lake, an ancient lake of Myanmar, with DNA barcoding, photo images and CT/3D models

ミャンマーの古代湖インレー湖で一世紀ぶりに魚類相調査, 約四割が外来魚。標本の3Dモデルもオンライン公開. 京都大学プレスリリース. 2016-12-02.Background: Inle (Inlay) Lake, an ancient lake of Southeast Asia, is located at the eastern part of Myanmar, surrounded by the Shan Mountains. Detailed information on fish fauna in and around the lake has long been unknown, although its outstanding endemism was reported a century ago

Origin of endemic species in a moderately isolated ancient lake: The case of a snakehead in Inle Lake, Myanmar

Inle Lake is an ancient lake in Myanmar, which is an important area with unique and diverse fauna. Its ichthyofauna is believed to have formed non-radiatively, but the historical processes are poorly understood. To elucidate the mechanisms that shape species diversity in this moderately isolated biogeographical ‘island’, this study focused on a typical endemic fish of Inle Lake, Channa harcourtbutleri (Channidae, Anabantiformes), with its widely distributed sister species, C. limbata, and estimated the historical distribution and diversification processes of the endemic fish based on genome-wide polymorphism (MIG-seq) and mitochondrial DNA data. Channa harcourtbutleri contained two genetically and morphologically distinct groups inhabiting Inle Lake and the surrounding rivers respectively. These two groups were genetically the closest to each other; however, the riverine group showed some similarity to the closely related species, C. limbata from Southeast Asia. The mtDNA haplotypes of the endemic species were not monophyletic; most of the riverine group had haplotypes identical or close to those of C. limbata from the upper Irrawaddy and Salween rivers. The time tree suggested that C. harcourtbutleri diverged from C. limbata in the early Pleistocene and then experienced secondary contact with C. limbata in the late Pleistocene. Genetic and morphological differentiation within C. harcourtbutleri suggests that local adaptation to different environments has played an important role for the coexistence of its two forms with some reproductive isolation. Further, the results highlight the importance of multiple colonization and allopatric speciation in shaping biodiversity in the long-term, moderately isolated environments

Fish diversity of a spring field in Hopong Town, Taunggyi District, Shan State, Myanmar (the Salween River Basin), with genetic comparisons to some “species endemic to Inle Lake”

Hopong, a small town in the Salween (Thanlwin) River Basin, Myanmar, is located 35 km northeast of Inle Lake, a famous ancient lake with numerous endemic fish species. We surveyed the fish fauna of a spring pond in Hopong in 2016, 2019 and 2020 and identified 25 species. Of these, seven, including Inlecypris auropurpureus and Sawbwa resplendens, had been considered endemic to Inle Lake and at least three species were genetically unique. Eight were suspected or definite introduced species, including Oreochromis niloticus and Gambusia affinis. We were unable to identify a nemacheilid species of the genus Petruichthys, which would need a taxonomic examination. The Hopong area is being developed rapidly and, hence, it is crucial to conserve its native fish species and the freshwater ecosystems

Interploidy gene flow involving the sexual-asexual cycle facilitates the diversification of gynogenetic triploid Carassius fish

クローン繁殖フナは稀に有性生殖をしながら繁栄 --遺伝的に多様なクローンフナが存在する謎を解明--. 京都大学プレスリリース. 2021-11-19.Asexual vertebrates are rare and at risk of extinction due to their restricted adaptability through the loss of genetic recombination. We explore the mechanisms behind the generation and maintenance of genetic diversity in triploid asexual (gynogenetic) Carassius auratus fish, which is widespread in East Asian fresh waters and exhibits one of the most extensive distribution among asexual vertebrates despite its dependence on host sperm. Our analyses of genetic composition using dozens of genetic markers and genome-wide transcriptome sequencing uncover admixed genetic composition of Japanese asexual triploid Carassius consisting of both the diverged Japanese and Eurasian alleles, suggesting the involvement of Eurasian lineages in its origin. However, coexisting sexual diploid relatives and asexual triploids in Japan show regional genetic similarity in both mitochondrial and nuclear markers. These results are attributed to a unique unidirectional gene flow from diploids to sympatric triploids, with the involvement of occasional sexual reproduction. Additionally, the asexual triploid shows a weaker population structure than the sexual diploid, and multiple triploid lineages coexist in most Japanese rivers. The generated diversity via repeated interploidy gene flow as well as an increased establishment of immigrants is assumed to offset the cost of asexual reproduction and might contribute to the successful broad distribution of this asexual vertebrate

Genetic population structure of Hemigrammocypris rasborella (Cyprinidae) inferred from mtDNA sequences

The genetic population structure of the small cyprinid Hemigrammocypris rasborella, distributed widely in lowlands of western Japan, was examined using partial sequence data of mitochondrial DNA (mtDNA). Molecular phylogenetic analysis revealed that the populations of the western Kyushu region were markedly differentiated from all eastern populations, such that the groups would be comparable to different species; their divergence was inferred to have occurred in the Late Miocene–Pliocene. Also, a largely divergent mtDNA group (with divergence in the early Pleistocene) was found in the Sanyo and northeastern Shikoku regions, forming a secondary contact zone in the western Kinki with the eastern mtDNA group. To date, these aspects of the population structure of H. rasborella appear to be unique among lowland fishes in western Japan. Deeper understanding of the formation processes of freshwater faunas in western Japan will require further comparisons of the phylogeographic patterns and ecological traits of constituent species

The origins of limnetic forms and cryptic divergence in Gnathopogon fishes (Cyprinidae) in Japan

The cyprinid species of the genus Gnathopogon, exhibiting flexible morphological and ecological variation, include limnetic life forms. We examined the origin of the limnetic forms and the population divergence of the Japanese Gnathopogon species, using molecular phylogenetic and phylogeographic analyses. A Bayesian phylogenetic inference approach based on mtDNA cytochrome b sequence data revealed three major lineages in G. elongatus. One of them formed a monophyletic group with the limnetic species G. caerulescens, which is endemic to an ancient lake, Lake Biwa. The divergence of the G. caerulescens lineage was estimated to date back to the early Pleistocene. This precedes the formation of the extensive pelagic environment in the present Lake Biwa. However, the recent genetic divergence of G. caerulescens was inferred to originate in the present Lake Biwa in the late Pleistocene. Another lacustrine population in the Mikata Lakes was shown to belong to a different lineage from G. caerulescens. The majority of the population possessed unique, but non-monophyletic, haplotypes, suggesting a short evolutionary history. One of the cryptic lineages of G. elongatus discovered in the Ina Valley, the lower area of Lake Suwa, might be related to the extinct lacustrine subspecies G. elongatus suwae, which has been replaced by introduced congeners. The previous and ongoing introductions of Gnathopogon fishes would have produced genetic disturbance to the indigenous populations