Shiho Kamakura, Taisuke Ohtsuka, Tamotsu Nagumo, Shinya Sato
{"title":"Differential cell size reduction of two sympatric Epithemia (Bacillariophyta) taxa in Nakaikemi Wetland, Japan","authors":"Shiho Kamakura, Taisuke Ohtsuka, Tamotsu Nagumo, Shinya Sato","doi":"10.1111/pre.12542","DOIUrl":"https://doi.org/10.1111/pre.12542","url":null,"abstract":"We observed contrasting temporal changes in cell size between two <i>Epithemia</i> taxa. The life cycle of diatoms is closely linked to their cell size, with a gradual decrease during the vegetative stage and a recovery through sexual reproduction. Sexual reproduction is triggered when cells become smaller than a species-specific size threshold and receive species-specific environmental cues. Few studies have documented the life cycles and frequency of sexual reproduction in diatoms, combining field observations and laboratory culture. We collected two <i>Epithemia</i> taxa, <i>Epithemia gibba</i> var. <i>ventricosa</i> and <i>Epithemia</i> sp. from a pond in Nakaikemi Wetland, and measured their valve lengths monthly for almost 3 years. Additionally, we established cultures of both taxa to examine the rates of cell size reduction, which affect the duration of the vegetative stage. In the field, <i>E. gibba</i> var. <i>ventricosa</i> exhibited a wide range of cell sizes and signs of size recovery. Furthermore, the cultures of this taxon showed a clear decrease in cell size through division, suggesting that sexual reproduction is required for size recovery. On the other hand, <i>Epithemia</i> sp. showed no obvious change in cell size both in the field and in the laboratory. This suggests that either sexual reproduction is not necessary for this taxon to maintain its population or their life cycle extends over several years to several decades. Thus, our findings reveal congeneric taxa sharing a common habitat and substratum, yet exhibiting distinct sexual and asexual strategies. Furthermore, we question the validity of taxonomic classifications previously assigned to these diatoms based on the range of morphological characteristics observed in the present study.","PeriodicalId":20544,"journal":{"name":"Phycological Research","volume":null,"pages":null},"PeriodicalIF":1.5,"publicationDate":"2024-01-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139397369","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Román Manuel Vásquez-Elizondo, Erika Vázquez-Delfín, Daniel Robledo
{"title":"Growth and photosynthetic physiology of holopelagic Sargassum (Phaeophyceae) under laboratory conditions","authors":"Román Manuel Vásquez-Elizondo, Erika Vázquez-Delfín, Daniel Robledo","doi":"10.1111/pre.12541","DOIUrl":"https://doi.org/10.1111/pre.12541","url":null,"abstract":"Species of holopelagic <i>Sargassum</i> are responsible for Caribbean golden tides, commonly known as ‘<i>Sargassum</i> events’. These events mainly comprise <i>Sargassum fluitans</i> and <i>Sargassum natans</i> I, which are exposed to high levels of irradiance, but also self-shading within their floating masses. In this study, we grew <i>S. fluitans</i> and <i>S. natans</i> I and acclimated them to low-light conditions at 23°C in the laboratory to explore their responses to increasing light intensities. Photosynthesis, respiration, growth, and pigment content were evaluated over 3 weeks. <i>S. fluitans</i> and <i>S. natans</i> I photoacclimate to higher irradiances by decreasing their chlorophyll <i>a</i> and <i>c</i> contents. An increase in maximum photosynthesis and respiration rates was observed under high light, although differences occurred in the saturation irradiance and the initial slope of the photosynthesis versus irradiance curve. These adjustments were reflected in <i>S. fluitans</i> daily growth (from 2% to 7% d<sup>−1</sup> at low to high light, respectively) and tissue nitrogen content (1.6–2.7%) but were absent in <i>S. natans</i> I (~1% d<sup>−1</sup>). The photosynthetic physiology of <i>S. fluitans</i> under these conditions suggests lower light requirements without compromising growth; however, under high light a higher photosynthetic performance was observed. Combining physiological and growth studies in holopelagic <i>Sargassum</i> species will serve as a baseline to understand and explain the success and overgrowth of these species along the Caribbean coast.","PeriodicalId":20544,"journal":{"name":"Phycological Research","volume":null,"pages":null},"PeriodicalIF":1.5,"publicationDate":"2023-12-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139054493","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"A study of Klisinema koreana sp. nov. (Desertifilaceae, Cyanobacteria) from the Republic of Korea based on morphological, ecological and molecular analyses","authors":"So-Won Kim, Nam-Ju Lee, Ji-Ho Song, Ok-Min Lee","doi":"10.1111/pre.12536","DOIUrl":"https://doi.org/10.1111/pre.12536","url":null,"abstract":"Genus <i>Klisinema</i> (Desertifilaceae, Desertifilales) has only one species, <i>Klisinema persicum</i>, reported worldwide, and this species was found in soils around thermal springs (50°C) of high radiation regions. Simple filament cyanobacteria belonging to the genus <i>Klisinema</i> were collected from Korea, and cultured samples were studied through morphological, ecological and molecular analyses. Both Korean <i>K. persicum</i> and <i>Klisinema koreana</i> were found as epilithic species in freshwater gravel, which have different ecological characteristics from previously reported <i>K. persicum</i>. As a result of morphological analysis, keritomized cytoplasm was observed in <i>K. koreana</i>, and this feature was also newly observed in <i>K. persicum</i> that was discovered in Korea. In addition, <i>K. koreana</i> has a larger width/length ratio compared to <i>K. persicum</i>, and both species have an irregular thylakoid arrangement. Furthermore, as a result of phylogenetic analysis of 16S rRNA, the genus <i>Klisinema</i> formed a monophyletic lineage, and <i>K. koreana</i> strains were clearly separated from <i>K. persicum</i> strains to form a phylogenetic tree. Moreover, when comparing the secondary structure of the 16S–23S internal transcribed spacer region, <i>K. koreana</i> has a structural difference from <i>K. persicum</i>, especially in the structure of the Box-B helix. Therefore, <i>Klisinema koreana</i> sp. nov. was proposed as a new species belonging to the genus <i>Klisinema</i> of family Desertifilaceae.","PeriodicalId":20544,"journal":{"name":"Phycological Research","volume":null,"pages":null},"PeriodicalIF":1.5,"publicationDate":"2023-12-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138715898","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Evolutionary analysis of MID homologs during the transition from homothallic species to heterothallic species in Volvox sect. Volvox (Chlorophyceae)","authors":"Shion Yamagishi, Kayoko Yamamoto, Kohei Takahashi, Hiroko Kawai-Toyooka, Shigekatsu Suzuki, Ryo Matsuzaki, Haruyo Yamaguchi, Masanobu Kawachi, Tetsuya Higashiyama, Hisayoshi Nozaki","doi":"10.1111/pre.12538","DOIUrl":"https://doi.org/10.1111/pre.12538","url":null,"abstract":"The diversity and the evolution of mating systems have been studied in various eukaryotes. <i>Volvox</i> sect. <i>Volvox</i> of the volvocine green algae is suitable for evolutionary studies of the transition from homothallic to heterothallic mating systems because this transition is recognized in distal lineages within <i>Volvox</i> sect. <i>Volvox</i>. <i>MID</i> homologs are important in determining the mating type minus and male in heterothallic species of the volvocine algae. However, <i>MID</i> homologs have not been studied within the entire <i>Volvox</i> sect. <i>Volvox</i>. Here, we analyzed <i>MID</i> homologs from almost all taxa of <i>Volvox</i> sect. <i>Volvox</i> and found no significant differences in <i>MID</i> sequences between homothallic species and males of heterothallic species. Furthermore, <i>MID</i> of the male genotype of the heterothallic <i>Volvox rousseletii</i> showed an expression pattern that was almost identical to that of a closely related homothallic species, <i>Volvox ferrisii</i>. Therefore, the function of <i>MID</i> might have been conserved within the ancestral homothallic lineage of <i>Volvox</i> sect. <i>Volvox</i> and during the evolutionary transition of the heterothallic male genotype from the ancestral homothallic species, possibly related to male gametogenesis.","PeriodicalId":20544,"journal":{"name":"Phycological Research","volume":null,"pages":null},"PeriodicalIF":1.5,"publicationDate":"2023-11-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138507448","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Trentepohlia brevicellulis comb. et stat. nov. (Trentepohliaceae, Ulvophyceae) found in Japan","authors":"Shinji Handa, Miho Nakahara-Tsubota, Izumi Shoda, Aya Mizobuchi, Taketo Nakano, Hiromi Tsubota","doi":"10.1111/pre.12537","DOIUrl":"https://doi.org/10.1111/pre.12537","url":null,"abstract":"The family Trentepohliaceae contains many common aerial algae, most widely distributed, particularly in tropical and subtropical regions. Eight species of the genus <i>Trentepohlia</i> have been reported in Japan. We report another taxon, <i>Trentepohlia brevicellulis</i> (Cribb) S. Handa and H. Tsubota comb. et stat. nov., growing on bark in western Honshu, Japan. This alga was previously described as <i>Trentepohlia bosseae</i> var. <i>brevicellulis</i> Cribb. However, the relationship between the <i>bosseae</i> and <i>brevicellulis</i> varieties of <i>T. bosseae</i> could not be ascertained owing to the lack of genetic information for <i>brevicellulis</i>. Therefore, we aimed to examine the detailed morphological characteristics of <i>brevicellulis</i> in wild samples and cultured strains and to review the taxonomy, including systematic information obtained by genetic analysis. Its phylogenetic position was resolved based on 18S rDNA sequence data. It differs from <i>T. bosseae</i> and its variety <i>samoensis</i> in exhibiting a warty zoosporangium surface, an unthickened septum with no central pit field, and a non-rusty-brown cell wall. The four key characteristics of <i>T. brevicellulis</i> include a warty layer on the inner surface of the non-bent side of the suffultory cell wall, an ostiole located near the base of the zoosporangium, curved tapering filaments with thickened cell walls, and globular vegetative spores in the basal portion of the filament. Transmission electron microscopy revealed a pit field wherein simple plasmodesmata were present in the septum. Phylogenetic analysis suggested that this alga and <i>T. bosseae</i> form distinct clades and that <i>T. brevicellulis</i> is separate from <i>T. bosseae</i>. Thus, our study helped redefine the accurate taxonomic position of the species under study as <i>Trentepohlia brevicellulis</i> (Cribb) S. Handa and H. Tsubota comb. et stat. nov., a clade distinct from <i>T. bosseae</i> and reported for the first time in Japan.","PeriodicalId":20544,"journal":{"name":"Phycological Research","volume":null,"pages":null},"PeriodicalIF":1.5,"publicationDate":"2023-11-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138507454","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Swimming zygote formation mediated by symmetrically arranged cell fusion sites in the gametes of <i>Chlamydomonas eugametos</i> (<scp>Chlorophyceae, Chlorophyta</scp>)","authors":"Shinichi Miyamura","doi":"10.1111/pre.12535","DOIUrl":"https://doi.org/10.1111/pre.12535","url":null,"abstract":"SUMMARY The spatial arrangement of cell fusion sites and eyespots of the gametes in vis‐à‐vis mating pairs of Chlamydomonas eugametos , corresponding to the swimming zygote of Chlamydomonas reinhardtii , were studied using field emission scanning electron microscopy and light microscopy, respectively. After the adhesion of mt + and mt − gametes, each of which has one eyespot and two flagella elongated from the cell anterior, gamete–gamete fusion occurred at the anterior papilla on the cell apex of each gamete, leading to the formation of a vis‐à‐vis mating pair, indicating that the cell fusion site is arranged symmetrically relative to the flagellar beat plane. In vis‐à‐vis mating pairs, two eyespots could be seen on the same or on opposite sides of the cell. As only the mt + flagella and eyespot are functional for swimming and phototaxis in the vis‐à‐vis mating pair of C. eugametos , it is suggested that coordinated alignment of the parental gamete flagella and eyespots in the swimming zygote and asymmetric positioning of the gamete mating structure/cell fusion sites, which is prevalent in C. reinhardtii and other chlorophytes, is not necessary for C. eugametos .","PeriodicalId":20544,"journal":{"name":"Phycological Research","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-11-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135634959","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Molecular and morphological characterization of three novel <i>Minorisa</i> species (Chlorarachnea) and proposal for an emended description of the <i>Minorisa minuta</i>","authors":"Takashi Shiratori, Yuta Kato, Ken‐ichiro Ishida","doi":"10.1111/pre.12533","DOIUrl":"https://doi.org/10.1111/pre.12533","url":null,"abstract":"SUMMARY Minorisa is a group of tiny uniflagellates belonging to the Cercozoa. These flagellates are the closest heterotrophic relatives of photosynthetic chlorarachniophytes and are one of the most abundant bacterivorous eukaryotes in coastal marine environments. Despite their evolutionary and ecological importance, taxonomic studies on Minorisa have not been conducted since the original description. In the present study, we isolated five Minorisa strains and performed molecular phylogenetic and microscopic analyses. Molecular phylogenetic analysis using small subunit ribosomal RNA gene sequences indicated that the strains form four different subclades in Minorisa . Microscopic observations revealed that these Minorisa strains possess an amoeboid stage that lacks a flagellum. In the amoeboid stage, cells possess lobose and/or extrusive pseudopodia. Based on the phylogenetic analysis and morphological observations, we revised the description of Minorisa and described the following three novel Minorisa species: Minorisa fusiformis sp. nov., Minorisa magna sp. nov. and Minorisa megafusiformis sp. nov.","PeriodicalId":20544,"journal":{"name":"Phycological Research","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-10-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135944117","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Anna V. Skriptsova, Oksana S. Belous, Svetlana Yu. Shibneva, Alexander A. Semenchenko
{"title":"Molecular study of the rare genus <scp><i>Neoabbottiella</i></scp> (Rhodophyta) reveals its assignment to the Halymeniaceae is incorrect","authors":"Anna V. Skriptsova, Oksana S. Belous, Svetlana Yu. Shibneva, Alexander A. Semenchenko","doi":"10.1111/pre.12534","DOIUrl":"https://doi.org/10.1111/pre.12534","url":null,"abstract":"SUMMARY The rare red algal genus Neoabbottiella from the Russian Pacific coast was taxonomically re‐examined. Currently, Neoabbottiella is assigned to the Halymeniales; however, some features of the reproductive anatomy cast doubt on the correctness of assigning the genus to Halymeniaceae sensu lato . We investigated the phylogenetic affinities of Neoabbottiella using four DNA markers (nuclear LSU and SSU rDNA, rbc L and COI‐5P). Neoabbottiella failed to group with any families of the Halymeniales, but it was nested in a highly supported clade containing representatives of the genus Schmitzia (Calosiphoniaceae incertae sedis ). Reproductive anatomy and post‐fertilization development also separate Neoabbottiella from the Halymeniaceae. The main characteristics distinguishing Neoabbottiella from the Halymeniales include the intercalary position of the auxiliary cell, the contact of the connecting filament with the auxiliary cell via the lateral process, the origin of the initial gonimoblast cell from the connecting filament at a distance from the auxiliary cell and a lack of a pericarp of branched ampullar filaments. These traits bring Neoabbottiella close to its genetic sister genus Schmitzia , making the classification of Neoabbottiella at the family and order levels difficult. The eventual taxonomic classification of Neoabbottiella awaits the input of data of other species of Schmitzia as well as Calosiphonia , the type genus of the Calosiphoniaceae; thus, Neoabbottiella should be provisionally excluded from the Halymeniales and considered as incertae sedis in the Rhodymeniophycidae. Further, the results of the present study showed that Neoabbottiella is monotypic; Neoabbottiella decipiens should be recognized as a synonym of the generitype Neoabbottiella araneosa .","PeriodicalId":20544,"journal":{"name":"Phycological Research","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-10-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"136079047","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}