Monitoring of reproductive health in the striped catfish Pangasianodon hypophthalmus (Sauvage, 1878) from the Saen Saep Canal, Thailand

Khlong Saen Saep is one of the most important and large canal systems in Bangkok, Thailand. However, the emergence of heavily polluted water has occasionally been reported due to the domestic sewage and industrial effluents discharged into the system. This situation may affect the reproductive status of aquatic lives residing in this canal. To evaluate the reproductive status of the canal inhabitant, the striped catfish Pangasianodon hypophthalmus (Sauvage, 1878)—a common dweller of the Saen Saep Canal—was collected from two selected stations, the Bumpen Nua Temple and the Kamalun Islam Mosque. The fish gonads were then anatomically and histologically examined. The results indicated that neither parasites nor ovary with external abnormality were found. Nevertheless, several histological alterations were detected, including vacuolar degeneration of previtellogenic oocytes, accumulation of melanomacrophage centers (MMCs), and atretic oocytes. Moreover, severe histopathological changes, such as the eosinophilic cytoplasm of spermatogonia, MMCs, blood congestion, and syncytium of spermatozoa, were observed in the fish testis. Our study suggested that the environmental stress and pollutions previously reported from the Saen Saep Canal possibly underpin the gonadal impairments of P. hypophthalmus examined and may have adverse impact on the reproductive health of others living in this canal syste

Comparative morphology and molecular evolution of marine interstitial cercozoans

The Cercozoa is an extremely diverse and poorly understood group of amoeboflagellated microeukaryotes that are united mainly by molecular phylogenetic data; a concrete synapomorphy at the morphological level has yet to be identified for the group. In order to better understand the biodiversity and evolutionary history of this lineage, I explored several marine benthic habitats in British Columbia, Canada and characterized novel cercozoans with high-resolution light microscopy and electron microscopy. Comparative ultrastructural studies using scanning and transmission electron microscopy on some of the newly discovered taxa demonstrated several novel features, including putative primary endosymbionts in one lineage (i.e., Auranticordis) and homologous patterns of muciferous bodies beneath the cell surface in another lineage. I coupled these morphological data with molecular phylogenetic analyses of small subunit (SSU) and large subunit (LSU) rDNA sequences and comparative analyses of polyubiquitin genes. This approach provided evidence that a concatenation of SSU and LSU rDNA sequences improves the phylogenetic resolution within the Cercozoa and that an insertion of one or two amino acids at the junctions between monomers in the polyubiquitin gene is a universal molecular signature for cercozoans (and foraminiferans). This study also enabled me to discover and describe eleven new species and five new genera, which underscores how poorly we currently understand the diversity of these marine microeukaryotic predators. The acquired SSU rDNA sequences from these novel lineages enabled me to provide the cellular identities of several environmental DNA sequence clades previously containing only uncharacterized taxa; these data also demonstrated the effectiveness of using a 600-bp fragment of the SSU rRNA gene for delimiting cercozoan species with limited morphological variation.Science, Faculty ofZoology, Department ofGraduat

Morphology and molecular phylogeny of a marine interstitial tetraflagellate with putative endosymbionts: Auranticordis quadriverberis n. gen. et sp. (Cercozoa)

Background: Comparative morphological studies and environmental sequencing surveys indicate that marine benthic environments contain a diverse assortment of microorganisms that are just beginning to be explored and characterized. The most conspicuous predatory flagellates in these habitats range from about 20–150 μm in size and fall into three major groups of eukaryotes that are very distantly related to one another: dinoflagellates, euglenids and cercozoans. The Cercozoa is a diverse group of amoeboflagellates that cluster together in molecular phylogenies inferred mainly from ribosomal gene sequences. These molecular phylogenetic studies have demonstrated that several enigmatic taxa, previously treated as Eukaryota insertae sedis, fall within the Cercozoa, and suggest that the actual diversity of this group is largely unknown. Improved knowledge of cercozoan diversity is expected to help resolve major branches in the tree of eukaryotes and demonstrate important cellular innovations for understanding eukaryote evolution. Results A rare tetraflagellate, Auranticordis quadriverberis n. gen. et sp., was isolated from marine sand samples. Uncultured cells were in low abundance and were individually prepared for electron microscopy and DNA sequencing. These flagellates possessed several novel features, such as (1) gliding motility associated with four bundled recurrent flagella, (2) heart-shaped cells about 35–75 μm in diam., and (3) bright orange coloration caused by linear arrays of muciferous bodies. Each cell also possessed about 2–30 pale orange bodies (usually 4–5 μm in diam.) that were enveloped by two membranes and sac-like vesicles. The innermost membrane invaginated to form unstacked thylakoids that extended towards a central pyrenoid containing tailed viral particles. Although to our knowledge, these bodies have never been described in any other eukaryote, the ultrastructure was most consistent with photosynthetic endosymbionts of cyanobacterial origin. This combination of morphological features did not allow us to assign A. quadriverberis to any known eukaryotic supergroup. Thus, we sequenced the small subunit rDNA sequence from two different isolates and demonstrated that this lineage evolved from within the Cercozoa. Conclusion Our discovery and characterization of A. quadriverberis underscores how poorly we understand the diversity of cercozoans and, potentially, represents one of the few independent cases of primary endosymbiosis within the Cercozoa and beyond.Science, Faculty ofZoology, Department ofNon UBCReviewedFacult

Transmission electron micrographs (TEM) showing the ultrastructure of putative primary endosymbionts in n

gen. et sp. Low magnification TEM showing four putative endosymbionts, each surrounded by sac-like vesicles (sc) defined by an outer membrane (Bar = 2 μm). High magnification TEM showing two enveloping inner membranes (arrowheads) and thylakoids (arrows) that are continuous with the innermost enveloping membrane (Bar = 0.2 μm). TEM showing the thylakoids, the sac-like vesicle (sc), and a cleavage furrow indicative of division (arrowheads) (Bar = 0.5 μm). High magnification TEM showing the central core of an endosymbiont containing viral particles (arrowheads) (Bar = 0.5 μm). High magnification TEM showing a pronounced invagination of the innermost enveloping membrane (arrowhead) (Bar = 0.5 μm). High magnification TEM showing the membrane (arrowheads) that defines the sac-like vesicle (sc) and the two innermost enveloping membranes (double arrowheads) (Bar = 0.2 μm). TEM showing viral particles (arrowhead) consisting of a polygonal head and tail, and positioned within the core of an endosymbiont (Bar = 0.5 μm). An inset showing a complete tailed viral particle (Bar = 0.2 μm).<p><b>Copyright information:</b></p><p>Taken from "Morphology and molecular phylogeny of a marine interstitial tetraflagellate with putative endosymbionts: n. gen. et sp. (Cercozoa)"</p><p>http://www.biomedcentral.com/1471-2180/8/123</p><p>BMC Microbiology 2008;8():123-123.</p><p>Published online 22 Jul 2008</p><p>PMCID:PMC2500021.</p><p></p

Fusiforma themisticola n. gen., n. sp., a New Genus and Species of Apostome Ciliate Infecting the Hyperiid Amphipod Themisto libellula in the Canadian Beaufort Sea (Arctic Ocean), and Establishment of the Pseudocolliniidae (Ciliophora, Apostomatia)

A novel parasitic ciliate Fusiforma themisticola n. gen., n. sp. was discovered infecting 4.4% of the hyperiid amphipod Themisto libellula. Ciliates were isolated from a formaldehyde-fixed whole amphipod and the DNA was extracted for amplification of the small subunit (SSU) rRNA gene. Sequence and phylogenetic analyses showed unambiguously that this ciliate is an apostome and about 2% divergent from the krill-infesting apostome species assigned to the genus Pseudocollinia. Protargol silver impregnation showed a highly unusual infraciliature for an apostome. There are typically 8 (6-9) bipolar somatic kineties covering the banana-shaped body. The anterior end of the oral cavity begins about 1/3 of the body length from the anterior end and is composed of an inpocketing that is lined on its anterior and left wall with an oral field of densely packed ciliated kinetosomes. Stomatogenesis begins with some dedifferentiation of the parental oral field and elongation of its paroral and oral kineties. A new oral field develops midventrally and the paroral and oral kineties break to form the oral apparatus of the opisthe, which completes development by additional kinetosomal proliferation and migration of the paroral. This morphology is novel among apostomes and justifies the establishment of a new genus and specie