Explore the vast range of titles available.

Dinoflagellates are known to possess chloroplasts of multiple origins derived from a red alga, a green alga, haptophytes, or diatoms. The monophyletic “dinotoms” harbor a chloroplast of diatom origin, but their chloroplasts are polyphyletic belonging to one of four genera: Chaetoceros, Cyclotella, Discostella, or Nitzschia. It has been speculated that serial replacement of diatom-derived chloroplasts by other diatoms has caused this diversity of chloroplasts. Although previous work suggested that the endosymbionts of Nitzschia origin might not be monophyletic, this has not been seriously investigated. To infer the number of replacements of diatom-derived chloroplasts in dinotoms, we analyzed the phylogenetic affinities of 14 species of dinotoms based on the endosymbiotic rbcL gene and SSU rDNA, and the host SSU rDNA. Resultant phylogenetic trees revealed that six species of Nitzschia were taken up by eight marine dinoflagellate species. Our phylogenies also indicate that four separate diatom species belonging to three genera were incorporated into the five freshwater dinotoms. Particular attention was paid to two crucially closely related species, Durinskia capensis and a novel species, D. kwazulunatalensis, because they possess distantly related Nitzschia species. This study clarified that any of a total of at least 11 diatom species in five genera are employed as an endosymbiont by 14 dinotoms, which infers a more frequent replacement of endosymbionts in the world of dinotoms than previously envisaged.

A new species of the dinoflagellate genus Bysmatrum was isolated from tidal pool samples originating from Cape Peninsula, South Africa. This new species was investigated by light, scanning and transmission electron microscopy, and its phylogenetic affinities were analyzed using molecular data. Cells were pentagonal in ventral view, 25-45 μm long and 20-42.5 μm wide and only slightly flattened in a dorsiventral plane. The epitheca, in apical view, was almost circular, with a slight ventral depression. Plate tabulation (P O , X, 4′, 3a, 7″, 6c, 4s, 5′′′, 2′′′′) was typical for the genus Bysmatrum. Apical plate 1′ was heptagonal and broadly asymmetric, with an elongated, fingerlike extension at the base. The intercalary plates 2a and 3a were separated by a direct connection between plates 3′ and 4″. The thecal plates were perforated by pores of different sizes and ornamented with linearly arranged reticulations. Intercalary bands were smooth, and antapical plates were not indented. This new species differs from the five other known species of the genus Bysmatrum in morphology (e.g. the shape of apical plate 1′) and it occupies an isolated position in phylogenetic trees inferred by analyses of small-subunit ribosomal DNA (SSU-rDNA) sequence data. This also represents the first report of the SSU rDNA sequence for Bysmatrum arenicola.

A non-toxic red tide with resulting anoxia was the cause of a major harmful algal bloom in St Helena Bay, South Africa, in February and March 2015. The red tide was observed along approximately 200 km of the Namaqua coastline extending well north of the Olifants River and southward into the bay. A maximum cell concentration of 14.32 × 10 6 cells l −1 was recorded in the southern reaches of the bay, and oxygen concentrations declined to as low as 0.06 ml l −1 in the shallow waters off Dwarskersbos. The hypoxia induced ecological fallout was significant with massive marine mortalities, including an estimated 415 tons of rock lobster (Jasus lalandii). The causative organism was identified morphologically, ultrastructurally and phylogenetically (using partial sequences of the 18S small subunit rDNA and the 28S large subunit rDNA) as Prorocentrum triestinum (Dinophyceae). Light and electron microscopy (both scanning and transmission) also facilitated identification of P. triestinum and addressed possible confusion with similar taxa. The global incidence of P. triestinum blooms is low, with hot spots limited to coastal areas in eastern China and the Mediterranean Sea, where blooms are sometimes associated with anthropogenic nutrient pollution. The harmful bloom documented here is the first exceptional bloom event with anoxic-related marine mortalities induced by P. triestinum in a major eastern boundary upwelling system such as the Benguela.

Pyramimonas vacuolata Suda, Horiguchi & Sym sp. nov. is described from Okinawa-jima Island, Japan. The species has been characterized using light and electron microscopy and its phylogenetic position inferred based on 18S rDNA and rbcL gene sequences relative to other species. Strains of P. vacuolata were isolated from coastal sand samples collected from two localities in Okinawa-jima. The cells are quadriflagellate but remarkably large for the genus, and the posterior half of the cell is vacuolated. The single parietal chloroplast is olive-green and contains two conspicuous pyrenoids lying on the same transverse plane, slightly anterior to the equatorial region of the cell. The pyrenoids are surrounded by numerous starch grains, and thylakoids randomly traverse the pyrenoid matrix. Two monolayered eyespots are present, situated on the same transverse plane as the pyrenoids. The alga possesses three types of body scales and four types of flagellar scales, inclusive of two types of hair scales. This species is readily distinguished from known species of Pyramimonas by its large cell size, the conspicuous posterior vacuole and the presence of two pyrenoids. The most obvious character of this species is its large posterior vacuole, and this prompted the adoption of the specific epithet 'vacuolata'. Analysis of 18S rDNA and rbcL gene sequences of P. vacuolata relative to those of other species of Pyramimonas shows that it falls, with strong support, in a monophyletic clade representing the subgenus Pyramimonas.

It is unclear whether the methodology was geared to test a specific hypothesis or to find a model that best fit the selected variables. The author's framing of the commentary suggests that it was meant to test the hypothesis that a number of pre-selected variables may influence a student's choice when considering studies in the biological sciences. However, as written, the analytical approach appears to use model selection, rather than test an a priori hypothesis. The author describes variables that appear to be sequentially added to the model before a best-fit model is selected. Instead of using the best-fit models, where 'black South African' is no longer a significant variable, the author makes inferences about each model. Further, the variable that makes the largest contribution to explaining variability in the Regression 2 is 'Agrees 'I support wildlife conservation but have no interest in having a career in it\". At this point, the variable 'black South African' is far from significant and no interaction effect is shown to support that these are linked to the dependent variable.

In 1988 and 1989, an undescribed gymnodinioid dinoflagellate species turned the waters of the largest bay in South Africa, False Bay, to a dirty olive-green colour. The bloom was accompanied by extensive abalone ( Haliotis midae ) mortalities and noxious gases causing eye, nose, skin and throat irritations in humans. In 1995, another undescribed gymnodinioid species bloomed in the same bay but with no adverse effects on marine fauna or humans. These two species form an established component of the phytoplankton assemblage on the south coast of South Africa. They are described here as Karenia cristata Botes, Sym & Pitcher and K. bicuneiformis Botes, Sym & Pitcher. Karenia cristata has a straight apical groove elevated into an apical crest and extending down immediately to the right of the sulcal extension on the ventral side. The hypocone is asymmetrical, with the right lobe larger and more rounded than the left; the nucleus is central, with the bulk situated in the hypocone. Its pigment content is similar to that of K. mikimotoi and K. brevis . Other than K. brevis , K. bicuneiformis is significantly larger than the other Karenia species and is distinctly dorso-ventrally flattened. The hypocone is w-shaped and the epicone is conical, giving the cell a distinctly angular outline. Pairwise distance comparisons of partial large subunit (28S) rDNA sequences indicate that these two species are clearly different from other species within the genus.

In 1988 and 1989, an undescribed gymnodinioid dinoflagellate species turned the waters of the largest bay in South Africa, False Bay, to a dirty olive-green colour. The bloom was accompanied by extensive abalone (Haliotis midae) mortalities and noxious gases causing eye, nose, skin and throat irritations in humans. In 1995, another undescribed gymnodinioid species bloomed in the same bay but with no adverse effects on marine fauna or humans. These two species form an established component of the phytoplankton assemblage on the south coast of South Africa. They are described here as Karenia cristata Botes, Sym & Pitcher and K. bicuneiformis Botes, Sym & Pitcher. Karenia cristata has a straight apical groove elevated into an apical crest and extending down immediately to the right of the sulcal extension on the ventral side. The hypocone is asymmetrical, with the right lobe larger and more rounded than the left; the nucleus is central, with the bulk situated in the hypocone. Its pigment content is similar to that of K. mikimotoi and K. brevis. Other than K. brevis, K. bicuneiformis is significantly larger than the other Karenia species and is distinctly dorso-ventrally flattened. The hypocone is w-shaped and the epicone is conical, giving the cell a distinctly angular outline. Pairwise distance comparisons of partial large subunit (28S) rDNA sequences indicate that these two species are clearly different from other species within the genus. [PUBLICATION ABSTRACT]