Search

Gregarines are the most biodiverse group of apicomplexan parasites. This group specializes on invertebrate hosts (e.g., ascidians, crustaceans, and polychaetes). Marine gregarines are of particular interest because they are considered to be the earliest evolving apicomplexan lineage, having subsequently speciated (and radiated) through virtually all existing animal groups. Still, mechanisms governing the broad (global) distribution and speciation patterns of apicomplexans are not well understood. The present study examines Pacific lecudinids, one of the most species-rich and diverse groups of marine gregarines. Here, marine polychaetes were collected from intertidal zones. Single trophozoite cells were isolated for light and electron microscopy, as well as molecular phylogenetic analyses using the partial 18S rRNA gene. The cytochrome c oxidase subunit 1 gene was used to confirm morphology-based host identification. This study introduces Undularius glycerae n. gen., n. sp. and Lecudina kitase n. sp. (Hokkaido, Japan), as well as Difficilina fasoliformis n. sp. (California, USA). Occurrences of Lecudina cf. longissima and Lecudina cf. tuzetae (California, USA) are also reported. Phylogenetic analysis revealed a close relationship between L. pellucida, L. tuzetae, and L. kitase n. sp. Additionally, clustering among North Atlantic and Pacific L. tuzetae formed a species complex, likely influenced by biogeography., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier GmbH. All rights reserved.)

Gregarines are an early-diverging lineage of apicomplexan parasites that hold many clues into the origin and evolution of the group, a remarkable transition from free-living phototrophic algae into obligate parasites of animals. 1 Using single-cell transcriptomics targeting understudied lineages to complement available sequencing data, we characterized the mitochondrial metabolic repertoire across the tree of apicomplexans. In contrast to the large suite of proteins involved in aerobic respiration in well-studied parasites like Toxoplasma or Plasmodium, 2 we find that gregarine trophozoites have significantly reduced energy metabolism: most lack respiratory complexes III and IV, and some lack the electron transport chains (ETCs) and tricarboxylic acid (TCA) cycle entirely. Phylogenomic analyses show that these reductions took place several times in parallel, resulting in a functional range from fully aerobic organelles to extremely reduced "mitosomes" restricted to Fe-S cluster biosynthesis. The mitochondrial genome has also been lost repeatedly: in species with severe functional reduction simply by gene loss but in one species with a complete ETC by relocating cox1 to the nuclear genome. Severe functional reduction of mitochondria is generally associated with structural reduction, resulting in small, nondescript mitochondrial-related organelles (MROs). 3 By contrast, gregarines retain distinctive mitochondria with tubular cristae, even the most functionally reduced cases that also lack genes associated with cristae formation. Overall, the parallel, severe reduction of gregarine mitochondria expands the diversity of organisms that contain MROs and further emphasizes the role of parallel transitions in apicomplexan evolution., Competing Interests: Declaration of interests The authors declare no competing interests., (Copyright © 2021 Elsevier Inc. All rights reserved.)

This study set out to bolster morphological and molecular datasets of marine gregarine apicomplexans. Gregarines were sampled from the Sea of Japan and Northwest Pacific from cirratuliform polychaetes (Acrocirridae, Cirratulidae, and Flabelligeridae), as well as sipunculids. Trophozoites (feeding stages) were gathered for identification using light microscopy, scanning electron microscopy, and transmission electron microscopy. Cells were also collected for molecular phylogenetic analysis using 18S rDNA and 28S rDNA. As a result, three new species of Selenidium, S. planusae n. sp., S. validusae n. sp., and S. pyroidea n. sp. were described, and additional morphological and genetic data were gathered for an existing species, S. orientale; and Trollidium was established as a new genus. Trollidium akkeshiense n. gen. n. sp. possessed a unique, unsymmetrical organization of microtubules running the longitudinal length of one side of the trophozoite, corresponding to a zig-zag pattern of epicytic (surface) folds, and a flicking pattern of movement. Phylogenetic analyses of 18S rDNA and 28S rDNA showed that these portions of the ribosomal operon are able to resolve some relationships among Selenidium, while other lineages including Trollidium akkeshiense n. gen. n. sp. appeared to be highly influenced by long branch attraction. High evolutionary rates along the ribosomal operon of gregarines may hinder this marker from resolving deeper nodes among early apicomplexans., (Copyright © 2019 Elsevier GmbH. All rights reserved.)

This study describes a novel species of Haplozoon, H. ezoense n. sp., a dinoflagellate parasite isolated from the intestines of Praxillella pacifica (Polychaeta). Trophonts (feeding stages) of H. ezoense n. sp. were isolated and studied with scanning and transmission electron microscopy, and molecular phylogenetic analyses was performed using 18S rDNA and 28S rDNA. Trophonts had an average length of 120μm, and were linear, forming a single longitudinal row comprising a trophocyte with a stylet, an average of 14 gonocytes (width=10μm), and bulbous cells that we concluded were likely sporocytes. The surface of H. ezoense n. sp. was covered with projections of the amphiesma. Sections viewed under TEM revealed multiple triple membrane-bound organelles reminiscent of relic non-photosynthetic plastids within the gonocytes. Haplozoon ezoense n. sp., H. praxillellae, and H. axiothellae formed a well-supported clade in the 18S rDNA datasets. The sequences of H. ezoense n. sp. differed from H. praxillellae, a species of Haplozoon isolated from the same host species in the Northeast Pacific, at 88/1,748 bases; and 155/1,752 bases from H. axiothellae. Concatenated 18S rDNA and 28S rDNA datasets were unable to resolve the deeper relationships of Haplozoon in the context of dinoflagellates., (Copyright © 2018 Elsevier GmbH. All rights reserved.)

Gregarine apicomplexans are unicellular parasites commonly found in the intestines and coeloms of invertebrate hosts. Traits associated with the conspicuous feeding stage of gregarines, known as the trophozoite, have been used in combination with molecular phylogenetic data for species delimitation and the reconstruction of evolutionary history. Trophozoite morphology alone is often inadequate for inferring phylogenetic relationships and delimiting species due to frequent cases of high intraspecific variation combined with relatively low interspecific variation. The current study combined morphological data with small subunit (SSU) rDNA sequences to describe and establish two novel marine gregarine species isolated from the intestine of a polychaete host Lumbrineris inflata collected in British Columbia (Canada): Paralecudina anankea n. sp. and Lecudina caspera n. sp. The sister species to the host is Lumbrineris japonica, which can be found on the opposite side of the Pacific Ocean (Japan) and contains two different species of gregarine parasites: Paralecudina polymorpha and Lecudina longissima. Molecular phylogenetic analyses placed P. anankea n. sp. as the sister species to P. polymorpha and L. caspera n. sp. as the sister species to L. longissima. This phylogenetic pattern demonstrates a co-evolutionary history whereby speciation of the host (Lumbrineris) corresponds with simultaneous speciation of the two different lineages of intestinal gregarines (Paralecudina and Lecudina)., (© 2017 The Author(s) Journal of Eukaryotic Microbiology © 2017 International Society of Protistologists.)

The genus Amphidiniopsis is a benthic (sand-dwelling) lineage of thecate dinoflagellates, containing 19 morphologically diverse species. Past work has shown that some Amphidiniopsis species form a clade with the sand-dwelling Herdmania litoralis as well as some planktonic species in the family Protoperidiniaceae (i.e. the Monovela group). Still, our contemporary knowledge regarding Amphidiniopsis is limited, compared to the Protoperidiniaceae. To this end, we obtained 18S rDNA data from seven Amphidiniopsis species and a part of the 28S rDNA from four Amphidiniopsis species, with the goal of improving our understanding of phylogenetic relationships among Amphidiniopsis and the Monovela group. Results from the molecular phylogenetic analyses showed that Amphidiniopsis spp., with the exception of A. cf. arenaria, H. litoralis, and members within the Monovela group formed a single clade. Within the clade, relationships among Amphidiniopsis spp. and the Monovela group were more complicated - some subclades contained both representatives of Amphidiniopsis and the Monovela group. Our study suggests that habitat (benthic or planktonic), as well as traditionally used, general morphological characteristics, do not reflect molecular phylogenetic relationships, and that the taxonomy of the sand-dwelling genus Amphidiniopsis, and the planktonic family Protoperidiniaceae, should be reconsidered simultaneously., (Copyright © 2016 Elsevier GmbH. All rights reserved.)

The eugregarines are a group of apicomplexan parasites that mostly infect the intestines of invertebrates. The high level of morphological variation found within and among species of eugregarines makes it difficult to find consistent and reliable traits that unite even closely related lineages. Based mostly on traits observed with light microscopy, the majority of described eugregarines from marine invertebrates has been classified into a single group, the Lecudinidae. Our understanding of the overall diversity and phylogenetic relationships of lecudinids is very poor, mainly because only a modest amount of exploratory research has been done on the group and very few species of lecudinids have been characterized at the molecular phylogenetic level. In an attempt to understand the diversity of marine gregarines better, we surveyed lecudinids that infect the intestines of Pacific ascidians (i.e. sea squirts) using ultrastructural and molecular phylogenetic approaches; currently, these species fall within one genus, Lankesteria. We collected lecudinid gregarines from six ascidian host species, and our data demonstrated that each host was infected by a different species of Lankesteria: (i) Lankesteria hesperidiiformis sp. nov., isolated from Distaplia occidentalis, (ii) Lankesteria metandrocarpae sp. nov., isolated from Metandrocarpa taylori, (iii) Lankesteria halocynthiae sp. nov., isolated from Halocynthia aurantium, (iv) Lankesteria herdmaniae sp. nov., isolated from Herdmania momus, (v) Lankesteria cf. ritterellae, isolated from Ritterella rubra, and (vi) Lankesteria didemni sp. nov., isolated from Didemnum vexillum. Visualization of the trophozoites with scanning electron microscopy showed that four of these species were covered with epicytic folds, whereas two of the species were covered with a dense pattern of epicytic knobs. The molecular phylogenetic data suggested that species of Lankesteria with surface knobs form a clade that is nested within a paraphyletic assemblage species of Lankesteria with epicytic folds.

Gregarine apicomplexans are a diverse group of single-celled parasites that have feeding stages (trophozoites) and gamonts that generally inhabit the extracellular spaces of invertebrate hosts living in marine, freshwater, and terrestrial environments. Inferences about the evolutionary morphology of gregarine apicomplexans are being incrementally refined by molecular phylogenetic data, which suggest that several traits associated with the feeding cells of gregarines arose by convergent evolution. The study reported here supports these inferences by showing how molecular data reveals traits that are phylogenetically misleading within the context of comparative morphology alone. We examined the ultrastructure and molecular phylogenetic positions of two gregarine species isolated from the spaghetti worm Thelepus japonicus: Selenidium terebellaeRay 1930 and S. melongena n. sp. The ultrastructural traits of S. terebellae were very similar to other species of Selenidium sensu stricto, such as having vermiform trophozoites with an apical complex, few epicytic folds, and a dense array of microtubules underlying the trilayered pellicle. By contrast, S. melongena n. sp. lacked a comparably discrete assembly of subpellicular microtubules, instead employing a system of fibrils beneath the cell surface that supported a relatively dense array of helically arranged epicytic folds. Molecular phylogenetic analyses of small subunit rDNA sequences derived from single-cell PCR unexpectedly demonstrated that these two gregarines are close sister species. The ultrastructural differences between these two species were consistent with the fact that S. terebellae infects the inner lining of the host intestines, and S. melongena n. sp. primarily inhabits the coelom, infecting the outside wall of the host intestine. Altogether, these data demonstrate a compelling case of niche partitioning and associated morphological divergence in marine gregarine apicomplexans., (Copyright © 2014 Elsevier GmbH. All rights reserved.)

Gregarines are a diverse group of apicomplexan parasites with a conspicuous extracellular feeding stage, called a "trophozoite", that infects the intestines and other body cavities of invertebrate hosts. Although the morphology of trophozoites is very diverse in gregarines as a whole, high degrees of intraspecific variation combined with relatively low degrees of interspecific variation make the delimitation of different species based on trophozoite morphology observed with light microscopy difficult. The coupling of molecular phylogenetic data with comparative morphology has shed considerable light onto the boundaries and interrelationships of different gregarine species. In this study, we isolated a novel marine gregarine from the hepatic region of a Pacific representative of the hemichordate Glossobalanus minutus, and report the first ultrastructural and molecular data from any gregarine infecting this distinctive group of hosts. Molecular phylogenetic analyses of an SSU rDNA sequence derived from two single-cell isolates of this marine gregarine demonstrated a strong and unexpected affiliation with a clade of terrestrial gregarines (e.g. Gregarina). This molecular phylogenetic data combined with a comparison of the morphological features in previous reports of gregarines collected from Atlantic representatives of G. minutus justified the establishment of a new binomial for the new isolate, namely Caliculium glossobalani n. gen. et sp. The molecular phylogenetic analyses demonstrated a clade of terrestrial gregarines associated with a sequence acquired from a marine species, which suggest that different groups of terrestrial/freshwater gregarines evolved independently from marine ancestors., (© 2014 The Author(s) Journal of Eukaryotic Microbiology © 2014 International Society of Protistologists.)

Although archigregarines are poorly understood intestinal parasites of marine invertebrates, they are critical for understanding the earliest stages in the evolution of the Apicomplexa. Previous studies suggest that archigregarines are a paraphyletic stem group from which other lineages of gregarines, and possibly all other groups of apicomplexans, evolved. However, substantiating this inference is difficult because molecular phylogenetic data from archigregarines, in particular, and other gregarines, in general, are severely limited. In an attempt to help fill gaps in our knowledge of archigregarine diversity and phylogeny, we set out to discover and characterize novel lineages of archigregarines with high-resolution light and scanning electron microscopy and analyses of small subunit (SSU) rDNA sequences derived from single-cell (SC) PCR techniques. Here, we describe two novel species of Selenidium, namely Selenidium idanthyrsae n. sp. and S. boccardiellae n. sp., and demonstrate the surface morphology and molecular phylogenetic position of the previously reported species S. cf. mesnili. We also describe a novel genus of archigregarine, Veloxidium leptosynaptae n. gen., n. sp., which branches with an environmental sequence and, together, forms the nearest sister lineage to a diverse clade of marine eugregarines (i.e. lecudinids and urosporids). This molecular phylogenetic result is consistent with the hypothesis that archigregarines are deeply paraphyletic within apicomplexans, and suggests that convergent evolution played an important role in shaping the diversity of eugregarine trophozoites., (© 2012 The Author(s) Journal of Eukaryotic Microbiology © 2012 International Society of Protistologists.)

Marine benthic dinoflagellates within the genus Amphidinium were isolated from Guam and Okinawa. Isolated strains were identified to species-level using phylogenetic analyses of 28S rRNA and ITS-5.8S rRNA genes as well as microscopy. Of the six isolated strains, two were new species: A. pagoense sp. nov. and A. uduigamense sp. nov. Other isolates included strains of A. massartii and A. operculatum from Guam, and two strains of A. operculatum from Okinawa. Both new species were described using light and electron microscopy (SEM and TEM). The combination of characteristics that make A. pagoense sp. nov. unique includes a pair of centrally-located pyrenoids, variable cell shape, absence of scales and a long, curved ventral ridge. For A. uduigamense sp. nov., a combination of several morphological features distinguishes it from other species. These include a constriction near the anterior of the hypocone, two centrally located pyrenoids, a longitudinal flagellum inserted in the posterior one-third of the cell, cell size, cell division in the motile stage and the absence of scales. Toxicity was confirmed in these two novel species by testing methanol extracts in an Artemia bioassay. Previously unrecorded ITS rRNA gene sequences from A. operculatum were also sequenced from both locations. Species identified and newly described in this study expand the taxonomic knowledge of Amphidinium in the Pacific. [ABSTRACT FROM AUTHOR]

Marine benthic dinoflagellates within the genus Coolia have been reported to produce natural products, some of which are known to be toxic (i.e., cooliatoxin). To date, five species of Coolia have been reported in tropical and temperate waters around the world; however, very few studies have combined detailed morphological and molecular data with chemical analyses. In this study, a clonal culture of Coolia malayensis was isolated and mass cultivated from a coral reef on the island of Okinawa, Japan. Analysis of the thecal plate morphology and molecular phylogeny from 28S rDNA strongly supported the close relationship between this new isolate of C. malayensis from Okinawa and other isolates of C. malayensis from around the world. Following methanol extraction of 250 L of mass culture, chemical analyses using NanoLiquid chromatography mass spectrometry revealed the mass profiles of water-soluble and ethyl acetate-soluble parts. High-resolution mass spectrometry derived the molecular formulas of three novel disulphated polyether analogs of yessotoxin (C 56 H 78 O 18 S 2 1102.4 (Compound 1 ), C 57 H 80 O 18 S 2 1116.4 (Compound 2 ), and C 57 H 78 O 19 S 2 1130.4 (Compound 3 )); two potential homologous compounds (Compounds 4 and 5 ) were also observed on the high-resolution mass, albeit with low signal intensity. The five compounds in the C. malayensis from Okinawa are composed of less oxygen, compared to cooliatoxin and other analogs of yessotoxin, suggesting the metabolites produced by C. malayensis are unique to those previously reported from other strains of Coolia . [ABSTRACT FROM AUTHOR]

Marine gregarines are poorly understood apicomplexan parasites with large trophozoites that inhabit the body cavities of marine invertebrates. Two novel species of gregarines were discovered in polychaete hosts collected in Canada and Japan. The trophozoites of Trichotokara japonica n. sp. were oval to rhomboidal shaped, and covered with longitudinal epicytic folds with a density of six to eight folds/micron. The nucleus was situated in the middle of the cell, and the mucron was elongated and covered with hair-like projections; antler-like projections also extended from the anterior tip of the mucron. The distinctively large trophozoites of Trichotokara eunicae n. sp. lacked an elongated mucron and had a tadpole-like cell shape consisting of a bulbous anterior region and a tapered tail-like posterior region. The cell surface was covered with longitudinal epicytic folds with a density of three to five folds/micron. Small subunit ( SSU) r DNA sequences of both species were very divergent and formed a strongly supported clade with the recently described species Trichotokara nothriae and an environmental sequence (). This phylogenetic context combined with the morphological features of T. eunicae n. sp. required us to amend the description for Trichotokara. The sister clade to the Trichotokara clade consisted of environmental sequences and Lecudina polymorpha, which also possesses densely packed epicyctic folds (3-5 folds/micron) and a prominently elongated mucron. This improved morphological and molecular phylogenetic context justified the establishment of Paralecudina (ex. Lecudina) polymorpha n. gen. et comb. [ABSTRACT FROM AUTHOR]

• High diversity of Coolia found in Guam. • New lineage of C. canariensis , phylogroup IV, displaying cryptic diversity. • Extracts from C. malayensis toxic to Artemia sp. • C. palmyrensis, C. canariensis, C. tropicalis extracts are nontoxic to Artemia sp. • Chemical analysis of six strains of Coolia showing variation in toxin production. Coolia Meunier 1919 from benthic assemblages of Hawai'i and Guam were isolated and clonal cultures were established from single cells. Cultures were identified to species-level based on 28S rRNA and ITS-5.8S rRNA genes and tested for toxicity. In Hawai'i, two strains of C. malayensis were isolated. In Guam, a high biodiversity was identified: four strains of C. malayensis , one strain of C. palmyrensis , one strain of C. tropicalis , one strain of C. canariensis phylogroup III, and two strains forming a new phylogroup (phylogroup IV) of nontoxic C. canariensis. Morphology of the new C. canariensis phylogroup was described using light microscopy and scanning electron microscopy. Mass cultures and methanol extracts of representative cultures (C. malayensis, C. palmyrensis, C. canariensis, C. tropicalis) from Guam were prepared for liquid chromatography-mass spectrometry analysis. Chemical analyses revealed yessotoxin analogue C 56 H 78 O 18 S 2 is produced by C. malayensis, C. canariensis phylogroup IV and C. palmyrensis , but other analogues, C 57 H 80 O 18 S 2 and C 58 H 86 O 18 S 2 , were only found in C. malayensis (Okinawa) and C. canariensis phylogroup IV. Individual toxin profiles were also different over time for an Okinawa strain of C. malayensis (NIES-3637), highlighting intra and inter-species variation in Yessotoxin-analogue expression. Biological activity was tested using Artemia bioassay and toxicity was observed in Guam and Okinawa strains of C. malayensis. Strong support of four distinct clades within the C. canariensis species complex was recovered in phylogenetic analyses, despite morphological similarities. [ABSTRACT FROM AUTHOR]