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The present study compared the stress response of two microalgal strains – Arthronema africanum (Cyanoprokaryota) and Coelastrella sp. BGV (Chlorophyta), after heavy metals’ treatment. Changes of algal growth, pigment and protein content were analyzed after adding Cu, Cd and Pb (50 µM and 100 µM) to the nutrition medium. It was found that Cd and Pb significantly inhibited growth and protein biosynthesis of microalgae, but the effect of Cu remained less pronounced. In both strains, a decrease of chlorophyll content was observed, while carotenoid content markedly increased, especially in Coelastrella sp. BGV biomass. The addition of 100 µM Cd and 100 µM Pb to the medium caused a strong enhancement of malondialdehyde in both microalgal strains, which corresponded to the significant increase of superoxide dismutase and catalase activity. The antioxidant enzymes appeared to be differently altered by heavy metals’ exposure. The activity of SOD in the Arthronema africanum cells was most strongly affected by Cd, in contrast to Coelastrella sp. BGV that was highly increased by 100 µM Pb. The application of 100 µM Cd and 100 µM Pb increased in a similar manner catalase activity in both microalgae. The strains that were studied showed a high absorption capacity for metal ions, especially for Pb, which was absorbed largely than Cd and Cu. For that reason, we assumed that both microalga and, in particular, Coelastrella sp. BGV, could be successfully used for treatment of contaminated water bodies.

The economic challenges of microalgae biodiesel production, including the energy burden and water shortage, can be addressed simultaneously by using wastewater as a nitrogen source. However, as a major form of nitrogen, ammonium is toxic to most microalgae strains, which limits the use of ammonium-containing wastewater. High-ammonium-tolerant algal strains remain to be explored. In this study, a microalgal strain named HDMA-01, which was isolated from Lake Dongfeng in China, was selected using a high ammonium medium. Phylogenetic analysis suggested that HDMA-01 belongs to the genus Monoraphidium (Selenastraceae, Sphaeropleales), and both 18S ribosomal DNA and ITS sequences of HDMA-01 appeared to be new molecular records of the Monoraphidium species. HDMA-01 can multiply vigorously using acetic acid and ammonium in TAP medium, reaching a density of 2 ×107 mL−1 within 7 days. HDMA-01 showed strong tolerance for ammonium. At a high ammonium concentration of 14 mM, HDMA-01 achieved maximum biomass and lipid productivity of 78.9 mg L−1 day−1 and 13.8 mg L−1 day−1, which is the highest among other Monoraphidium strains under similar cultivation conditions. Together with its ideal fatty acid profile, HDMA-01 has great potential for development as a promising strain used in biodiesel feedstock and high-ammonium tolerance biotechnology.

Lanceola loveni antarctica and L. sphaerica are rare deep-sea species known from very few specimens. Until recently (Zeidler 2019) L. loveni antarctica was known only from the types, seven specimens (7–27 mm), from the Indian Ocean Sector of the Antarctic (Vinogradov 1962). Similarly, L. sphaerica, originally described as a variety of L. clausi (Vinogradov, 1957), based on two damaged specimens, a female (8.0 mm) and a male (9 mm), from the Kurile-Kamchatka region of the NW Pacific, later elevated to full species status by Vinogradov (1970) upon the discovery of a well-preserved male (5 mm) from the same general region, was until then known only from these three specimens. The recent discovery of several specimens of both species in the USNM (Zeidler 2019) has now made it possible to provide a more detailed redescription of these rare species, including some new distribution records.

This paper describes a new species from the Class Chlorophyceae, Mychonastes frigidus sp. nov., isolated from a cold-water mountain stream in the north of Russia (Subpolar Ural). The taxon is described using morphological and molecular methods. Mychonastes frigidus sp. nov. belongs to the group of species of the genus Mychonastes with spherical single cells. Comparison of ITS2 rDNA sequences and its secondary structures combined with the compensatory base changes approach confirms the separation between Mychonastes frigidus sp. nov and other species of the genus. Mychonastes frigidus sp. nov. represents a cryptic species that can only be reliably identified using molecular data.

The Pandanduri Dam has a function as a support for agricultural irrigation water and also supports community activities so that it will affect the quality of its waters. The quality of the water needs to be analyzed because it can affect the aquatic ecosystem. This study aims to determine the level of water pollution in the Pandanduri Dam based on the phytoplankton community from the Chlorophyta Division. This type of research is descriptive exploratory. Sampling was carried out at 5 stations that were haphazardly selected with ecological representativeness consideration. Phytoplankton data were analyzed using the abundance formula, Shannon-Wiener diversity index, PIELOU uniformity index, and Simpson dominance index. The phytoplankton from the Chlorophyta Division found in the Pandanduri Dam were 14 species that are Pediastrum duplex var. Gracillimum, Gonium sp. 1, Gonium sp. 2, Coelastrum reticulatum, Scenedesmus acuminatus, Cosmarium sp., Chlamydomonas nasuta, Chlamydomonas sp., Selenastrum capricornutum, Monoraphidium dybowskii, Monoraphidium contortum, Monoraphidium irregular, Westella botryoides, and Kirchneriella lunaris consisting of 4 orders (Sphaeropleales, Chlorococcales, Chlamydomonadales and Desmidiales) and 10 genera (Pediastrum, Coelastrum, Scenedesmus, Gonium, Cosmarium, Chlamydomonas, Selenastrum, Monoraphidium, Westella, and Kirchneriella). The species diversity index of 2.21 is classified as moderate diversity, the species uniformity index is 0.83 which indicates even species growth, and the species dominance index indicates that no species dominates with a value of 0.12. The level of water pollution in the Pandanduri Dam was found in the moderate pollution category (oligotrophic).

Sixteen monoclonal strains classified into six morphotypes typical of, or close to, intraspecific taxa of Pseudopediastum boryanum, including P. alternans (ALT), P. boryanum var. boryanum (BOR), P. boryanum var. cornutum (COR), P. boryanum var. forcipatum (FOR), P. boryanum var. longicorne (LON), and P. boryanum var. perforatum (PER), were simultaneously subjected to phylogenetic (26S rDNA and rbcL cpDNA) and morphometric analyses. Marginal cell shape, coenobium and cell size, and granule density on the cell surface were analyzed statistically. The shapes of some morphotypes (BOR, COR, FOR, and PER) were also compared to the shapes of corresponding type illustrations. Pseudopediastrum boryanum var. boryanum, without any reliable morphological and phylogenetic data, appeared to be a questionable taxon that needs a neotype. The variety longicorne proved to be a complex taxon that should be split after morphometric data of more strains and of the corresponding lectotype are included in the statistical analysis. A new species, Pseudopediastrum oblongum, was described, and four varieties were elevated to the species level, which resulted in establishing new combinations, P. cornutum, P. forcipatum, P. perforatum, and P. subgranulatum. Reference sequences for the new species and combinations were obtained. The paleoecological value of P. boryanum sensu lato appeared to be limited by the relatively low percentage of marginal cells typical of particular varieties and a high risk of their misidentification in the light microscope. The shape of marginal cells seemed to be the best diagnostic feature. Granule density could be helpful to discriminate between certain taxa.

The two genera Planktosphaeria (the type Pl. gelatinosa G.M.Smith) and Follicularia (the type F. paradoxalis Miller) have numerous chloroplast segments, each with a single pyrenoid. Autospore repro...

The genus Hariotina was established in 1889 based on the type species Hariotina reticulata. This species was then transferred to Coelastrum by Senn (1899). The genus Hariotina was eventually restor...

A new strain of Bracteacoccus bullatus Fucikova, Flechtner et L.A. Lewis belonging to green algae has been isolated from forest litter at a locust plantation located in a steppe zone of Ukraine. The strain has been identified by its morphological characteristics and via a phylogenetic analysis using the 18S rDNA gene and the ITS1–5.8S rDNA–ITS2 region. The new strain has been put into the monophyletic B. bullatus clade with a high statistical support. The study of its growth and lipid accumulation rates has allowed for achieving a dry biomass and total lipid content equal to 2.31 g/L and 55.84%, respectively, after a 15-day cultivation on 3N BBM medium. The analysis of fatty acid composition of the strain has shown the prevalence of palmitic 16:0, hexadecadiene 16:2(7Z,10Z), oleic 18:1(9Z), and linoleic 18:2(9Z,12Z) acids, which comprise 91.9% of the total fatty acid content. Compared to other Bracteacoccus strains, the strain MZ–Ch32 demonstrates the maximum content of omega-6 polyunsaturated fatty acids. With allowance for its growth characteristics and fatty acid profile, the new strain of B. bullatus can be considered as a potential producer of essential linoleic or oleic acids. A balanced ratio of omega-3 and omega-6 polyunsaturated fatty acids in the biomass makes it possible to use the strain as a component of forage and feeding additives in agriculture.

Lanceola sphaerica Vinogradov, 1970 Lanceola clausi var. sphaerica Vinogradov 1957: 196, fig. 6. Lanceola sphaerica Vinogradov, 1970: 383, 386���388, figs 1���2.��� Vinogradov et al. 1982 / 1996: 73���75 /84���86, fig. 20.���Zeidler 2009: 44���45, fig. 13.��� Zeidler 2019: 514. Material examined. Southern Ocean: immature female (USNM 1090248), Amundsen Sea, Cruise 11, station 930 [70��08���S 109��48���W], 1,391 m, 19 January 1964 (figured here). SE Pacific: immature female (USNM 1089971), off Chilean coast near Valdivia, Cruise 6, station 326 [38��19���S 74��34���W], 1,691���2,072 m, 25 November 1962. Type material. Lanceola sphaerica was first described as a variety of L. clausi from two damaged specimens, a mature female (8 mm) and a male (9 mm), both caught in the Kurile-Kamchatka region of the North-West Pacific. The female from Vityaz station 2076 [43��39���N 149��24���E], 4,200 ���7,800 m, 9 May 1953 and the male from Vityaz station 2208 [49��23���N 158��45���E], 0���6,500 m, 22 June 1953 (Vinogradov 1957). Later, Vinogradov (1970) established it as a full species with the availability of a well-preserved male (5.5 mm) from the same general area; Vityaz station 5626 [45��11���N 152��28���E], 3,000 ���4,000 m, 23���24 August 1966. All three specimens are in the Zoological Museum of the Moscow State University (Mb���1051, 1052, 1053). Description of immature female 4.5 mm (Fig. 3). Pereonites 1���4 inflated, almost spherical. Head without rostrum. Eyes very small, reniform, without crystalline cones. A1 slightly longer than head and first pereonite combined. A2 as long as A1 with two long setae terminally. G1; basis relatively slender, slightly shorter than remaining articles combined; carpus length 0.5 x basis, distal margin width about 1.3 x proximal margin of propodus; propodus conical-shaped, length about 2 x proximal width; dactylus length almost 0.5 x propodus. G2 much longer and slenderer than G1; basis length about 0.7 x remaining articles combined, about 2 x carpus length; propodus gradually tapering to narrow distal margin, length about 1.4 x carpus; dactylus inserted terminally to propodus, length about 0.4 x propodus. P3 and P4 similar in length and morphology; basis length slightly more than 2 x merus; merus with distinct antero-distal bulge, maximum width about 0.8 x length; carpus length 1.6 x merus for P3, 1.8 x merus for P4; propodus length 1.3 x carpus for P3, 1.1 x carpus for P4; dactylus length slightly more than 0.3 x propodus. P5���7 all with relatively long, slender articles and fully retractile, hooded dactyls but propodus not club-like distally. P5 slightly shorter than P4; basis length almost 2 x merus; carpus length 1.3 x merus, 0.8 x propodus; dactylus in relatively broad hollow. P6 length almost 1.3 x P5, slightly longer than first four pereonites combined; basis length about 2 x merus; merus with very slight postero-distal bulge; carpus length 1.5 x merus; propodus length about 1.4 x merus; dactylus strongly curved, pressed against anterior margin of propodus. P7 length 0.7 x P6; basis length 2.5 x merus; merus with slight postero-distal bulge; carpus length 1.2 x merus, about 0.6 x propodus. Urosome with relatively slender peduncles and rami. Rami of all uropoda more or less sub-equal in length, with slightly serrated margins. Peduncles and rami of U1 & U2 similar in length. Peduncle length of U3 slightly less than rami. Telson acute, apex rounded; length about 1.5 x width at base, reaching to about the middle of peduncle of U3. Remarks. Lanceola sphaerica is distinguished from all its congeners by a combination of several characters; i) the inflated pereon (especially in females); ii) the relatively long dactyls of P3���7 (especially P 3���4 in mature males); iii) the structure of P5 becoming sub-chelate in males; and iv) the relatively short telson. It is clearly most similar to the highly variable species, L. clausi, in the general habitus and the relative lengths of the pereopods but is readily distinguished by the slightly more inflated pereon and the relatively longer dactyls of P3���7. The female specimen described here is similar to L. clausi pirloti Shoemaker, 1945 in that the antennae are of similar length and the merus of P3���4 has a distinct antero-distal bulge, but differs from it in that the basis of the gnathopoda is slender; P6 is relatively longer and the uropoda are slenderer. In the long dactyls of P3 and P4, it resembles L. longidactyla Vinogradov, 1964 but in that species the dactyls are relatively much longer and P5 is not modified. It also resembles L. chelifera Vinogradov, 1970, especially in the modification of P5 but in that species the dactylus of P5 is not retractile or hooded and the structure of P3 and P4 is completely different. As noted by Vinogradov (1970), females of L. sphaerica differ from males in the following characters: i) P3 and P4 are more weakly armed and the dactyls are relatively shorter; ii) the articles of P5 are more linear, with less armature and the propodus is not robust and the dactylus is not as strong, not becoming sub-chelate. The specimen described here agrees with these characters and there are only very minor differences in the relative lengths of articles that can be determined from the limited information provided for the female by Vinogradov (1957, 1970). The sexual dimorphism exhibited in the morphology of P5 seems to become more prominent in mature males. Like L. clausi, L. sphaerica seems to occur in the colder waters of both Hemispheres. Distribution. Known only from the Kurile-Kamchatka region of the Pacific Ocean, the Amundsen Sea, Antarctica and the South-East Pacific, as detailed above. The latter is a new distribution record for L. sphaerica. Vinogradov (1970) records it as ���one of the most deeply-living hyperiids, being restricted to the abyssopelagic zone (including the trench waters) and does not rise above 3,000 m into the bathypelagic���, based on the specimens from the Kurile-Kamchatka region. It is recorded here from 1,391 m and 1,691 ���2,072 m., Published as part of Zeidler, Wolfgang, 2021, Redescription of two rare, deep-sea species of hyperiidean amphipod, Lanceola loveni antarctica Vinogradov, 1962 and L. sphaerica Vinogradov, 1970 (Crustacea: Amphipoda: Hyperiidea: Lanceolidae), pp. 106-114 in Zootaxa 5067 (1) on pages 111-113, DOI: 10.11646/zootaxa.5067.1.6, http://zenodo.org/record/5656569, {"references":["Vinogradov, M. E. (1970) New data on the amphipods Hyperiidea Physosomata of the northwest part of the Pacific. Trudy Instituta Okeanologii Akademiya Nauk SSSR, 86, 382 - 400. [in Russian; English translation: In: Bogorov, V. G. (Ed.), Fauna of the Kurile-Kamchatka Trench and its Environmen. Israel Program for Scientific Translations, Jerusalem, pp. 398 - 418 (1972)]","Vinogradov, M. E. (1957) Hyperiids (Amphipoda) of the Northwest Pacific Ocean. 1. Tribe Hyperiidea Physosomata. Trudy Instituta Okeanologii Akademiya Nauk SSSR, 20, 186 - 227. [in Russian; English translation: Marine Biology. Vol. 20. American Institute of Biological Sciences, Washington D. C., pp. 149 - 184 (1959)]","Vinogradov, M. E., Volkov, A. F. & Semenova, T. N. (1982) Amfipody-Giperiidy (Amphipoda: Hyperiidea) Mirovogo Okeanea. Akademiya Nauk SSSR, Opredeliteli po Faune SSSR, No. 132. Leningrad, 492 pp. [in Russian]","Vinogradov, M. E., Volkov, A. F. & Semenova, T. N. (1996) Hyperiid Amphipods (Amphipoda, Hyperiidea) of the World Oceans. Smithsonian Institution Libraries, D. Siegel-Causey, Scientific Editor, Washington D. C. and Oxonian Press Pvy. Ltd., New Delhi, 632 pp. [English translation from 1982 Russian original]","Zeidler, W. (2019) New and additional records of hyperiidean amphipods of the Infraorder Physosomata (Crustacea: Amphipoda: Hyperiidea) from the Antarctic Zone of the Southern Ocean. Zootaxa, 4576 (3), 510 - 520. https: // doi. org / 10.11646 / zootaxa. 4576.3.5","Shoemaker, C. R. (1945) The Amphipoda of the Bermuda Oceanographic Expeditions, 1929 - 1931. Zoologica, New York, 30 (4), 185 - 266. https: // doi. org / 10.5962 / p. 210854","Vinogradov, M. E. (1964) Hyperiidea Physosomata from the northern part of the Indian Ocean. Trudy Instituta Okeanologii Akademiya Nauk SSSR, 65, 107 - 151. [in Russian]"]}

We describe the plastome of Jenufa minuta, a unicellular green alga whose precise relationship with the Sphaeropleales (Chlorophyceae) remains uncertain. This 206,680-bp genome contains 100 conserv...

We sampled the first mitogenomes from a novel lineage of the Chlorophyceae that is sister to Sphaeropleales. Although the Jenufa perforata (27,180 bp) and Jenufa minuta (41,488 bp) mitogeno...

Mitogenome evolution in the Chlorophyceae is characterized by the acquisition of a reduced-derived pattern by the Chlamydomonadales + Sphaeropleales clade. Because no mitogenomes are available for the sister clade Oedogoniales + Chaetophorales + Chaetopeltidales, it remains unclear whether the common ancestor of chlorophycean green algae harbored a reduced-derived or ancestral-type mitogenome. The 70,191 and 46,765-bp mitogenomes reported here for Bulbochaete rectangularis var. hiloensis (Oedogoniales) and Stigeoclonium helveticum (Chaetophorales), respectively, shed light on this question. Both contain the same set of 41 conserved genes, a repertoire lacking numerous protein-coding genes but featuring all 27 tRNA genes typically found in ancestral-type mitogenomes.

We taxonomically examined an algal strain (Ki‐4) isolated from a dry asphalt surface in mid‐summer of 2003. The vegetative cells were solitary, covered by a cell wall ornamented with meridional ribs, and contained hollow spherical chloroplasts and a pyrenoid. The cells exhibited a high tolerance to unfavorable photo‐oxidative stress conditions, and in culture developed a reddish coloration due to the accumulation of a water‐soluble astaxanthin‐binding protein, which was identified as a novel protein in organisms. 18S rDNA and ITS2 sequence analyses revealed that Ki‐4 belongs to Coelastrella sensu lato (Scenedesmaceae), but was taxonomically distinct from other members of the genus. On the basis of its phylogenetic position and morphological features, including the structures of cell wall ribs, we identify Ki‐4 as a new algal species in the genus Coelastrella, for which we propose the name Coelastrella astaxanthina sp. nov.

The species diversity of green coccoid algae is often difficult to study using light microscopy due to their complex morphology. Algae, which have morphological and ecological similarities with the genera Bracteacoccus Tereg., Dictyococcus Gerneck, and Pseudomuriella Hanagata, are one of the most taxonomically complex examples. Often, only a comparison of nucleotide sequences allows one to carry out a reliable identification and find out the phylogenetic identity of the studied objects. Pseudomuriella belongs to the group of genetically diverse genera with a homogeneous Bracteacoccus-like morphology. The combined use of two genetic markers (18S rDNA nuclear gene and chloroplast rbcL gene), along with light microscopy and comparison of fatty acid profiles, allowed the identification of the green algae strain isolated from the soil of the artificial pine and robinia plantation in the steppe zone of Ukraine as Pseudomuriella engadinensis (Kol et Chodat) Fucikova, Rada et Lewis—the first find of the species in the flora of algae in Ukraine. Analysis of the fatty acid composition of the studied strain’s cells showed that the total lipid content in the stationary growth phase was at the level of 87.9 ± 2.1 mg/g dry cell mass, and the main fatty acids were palmitic, hexadecadienoic, ruganic, oleic, linoleic, and α-linolenic—their share accounted for 82.4% of the total amount of fatty acids.

In 2013, UNESCO classified the ‘University of Coimbra – Alta and Sofia’ (Portugal) as World Heritage site. Some of the limestone monuments that compose the site, such as the Old Cathedral of Coimbra, show clear visual effects of biological colonization by cyanobacteria and microalgae. The aim of this study was to thoroughly characterize the structural diversity of the photoautotrophic community at this site, combining isolation and molecular identification with next-generation sequencing techniques. Culture-dependent approaches resulted on the identification of green microalgae belonging to Prasiolales, Chlorellales, Watanabea, Chlamydomonadales and Sphaeropleales clades, and cyanobacteria belonging to Nostocales and Synechococcales clades. Culture-independent methods using Illumina Platform resulted in the identification of 610 Operational Taxonomic Units (OTUs), revealing the presence of populations within phyla Chlorophyta, Cyanobacteria, Rhodophyta and Stramenopiles/Bacillariophyta. In addition, principal component analysis (PCA) and a network analysis were generated and successfully related the different populations to specific biodeterioration scenarios observed at this monument. The use of culture-dependent and -independent techniques together with PCA and network analysis allowed us to understand the distribution patterns of the photoautotrophic community among the different biofilms observed at this monument, as well as their ecological specifications. This study highlights that both cultivation and metagenomics methodologies should be employed synergistically in similar biodeterioration studies.

The present study is the first to investigate the evolution of morphological variability and modularity of single (marginal) cells in two-dimensional colonial (coenobial) microscopic algae. Geometr...

We tested 37 photoautotrophic microalgal strains of various taxonomic positions for their heterotrophic growth on glucose. We showed that facultative heterotrophy was quite common among certain groups of green algae (Chlorellales or Sphaeropleales) and of Xanthophyceae, whereas it was completely absent from Eustigmatophyceae. For the first time, we found heterotrophy in some members of green algae (Botryosphaerella sudetica, Bracteacoccus sp., Dictyosphaerium spp., Lemmermannia sp., Parachlorella kessleri). Of the tested facultative heterotrophs, three strains, Scenedesmus sp., Dictyosphaerium chlorelloides, and Tribonema aequale, were selected to investigate, in detail, their mixotrophic growth and production of specific metabolites, carotenoids, exopolysaccharides, and eicosapentaenoic acid, respectively. Among them only T. aequale showed significantly higher production of the target compound, eicosapentaenoic acid, under the mixotrophic cultivation mode than photoautotrophically. Together with the ease of biomass harvest, Tribonema microalgae are therefore proposed as a possible source of high-quality ω-3 polyunsaturated fatty acids.

Reports of programmed cell death (PCD) across the taxonomic spectrum of photosynthetic unicellular organisms raise questions concerning its ecological and evolutionary roles. However, prior to ecological studies or evolutionary interpretations, it is essential to document phenotypic changes associated with PCD at the single-cell level, since death-related responses vary between taxa and within a single taxon depending on environmental stimuli. Here, we report responses to rapidly changing light, temperature and fluctuations in macronutrients in the model selenastracean green microalga Ankistrodesmus densus (Chlorophyta, Chlorophyceae, Sphaeropleales). We used stringent, but environmentally appropriate, conditions of prolonged darkness, nitrogen starvation (4 days), heat (1 h at 44°C) and cold shock (3 h at 2 ± 2°C). PCD phenotypes were examined by ultrastructural changes, phosphatidylserine (PS) externalization and DNA degradation. Flow cytometric Annexin V FITC analyses revealed that darkness and nitrogen-deprived cultures had significantly higher proportions of cells with PS externalization compared with controls (p < 0.05). Heat and cold treatments did not affect PS externalization (p = 0.44 and p = 0.99, respectively). Transmission electron microscopy (TEM) of light-deprived cells demonstrated, among other ultrastructural changes, marked cytoplasmic vacuolization suggesting a subtype of PCD known as vacuolar cell death. Nitrogen-starved cells had less vacuolization but presented more typical ultrastructural markers of PCD such as chromatin condensation and marginalization. In contrast, the more severe heat and cold shock treatments resulted in necrotic-like features. These findings suggest that prolonged darkness and nitrogen starvation induce PCD in a small (8.4 3.5 and 7.42 2.6%, respectively) but significant (p < 0.05) fraction of the A. densus population. Documenting these different death-related phenotypes depending on different environmental inducers is essential for interpreting ecological studies. Furthermore, our data support the hypothesis that autophagic/vacuolar cell death (VCD), which is central to organism homeostasis in plants (Streptophyta), occurs in Chlorophyta. VCD probably arose long before the evolution of multicellularity in plants. HIGHLIGHTSDarkness and nitrogen deprivation induce different programmed cell death markers in Ankistrodesmus densus;Plant vacuolar-like cell death occurs in Chlorophyta;There is crossover between the vacuolar and apoptosis-like death morphotypes. Darkness and nitrogen deprivation induce different programmed cell death markers in Ankistrodesmus densus; Plant vacuolar-like cell death occurs in Chlorophyta; There is crossover between the vacuolar and apoptosis-like death morphotypes.

Diverse algae possess the ability to recover from extreme desiccation without forming specialized resting structures. Green algal genera such as Tetradesmus (Sphaeropleales, Chlorophyceae) contain temperate terrestrial, desert, and aquatic species, providing an opportunity to compare physiological traits associated with the transition to land in closely related taxa. We subjected six species from distinct habitats to three dehydration treatments varying in relative humidity (RH 5%, 65%, 80%) followed by short- and long-term rehydration. We tested the capacity of the algae to recover from dehydration using the effective quantum yield of photosystem II as a proxy for physiological activity. The degree of recovery was dependent both on the habitat of origin and the dehydration scenario, with terrestrial, but not aquatic, species recovering from dehydration. Distinct strains of each species responded similarly to dehydration and rehydration, with the exception of one aquatic strain that recovered from the mildest dehydration treatment. Cell ultrastructure was uniformly maintained in both aquatic and desert species during dehydration and rehydration, but staining with an amphiphilic styryl dye indicated damage to the plasma membrane from osmotically induced water loss in the aquatic species. These analyses demonstrate that terrestrial Tetradesmus possess a vegetative desiccation tolerance phenotype, making these species ideal for comparative omics studies.

Diverse algae possess vegetative desiccation tolerance, the ability to recover from extreme desiccation without forming specialized resting structures. Green algal genera such as Tetradesmus (Sphaeropleales, Chlorophyceae) contain both terrestrial and aquatic species, providing an opportunity to compare physiological traits associated with the transition to land in closely related taxa. We subjected six species from aquatic and terrestrial habitats to three desiccation treatments varying in final relative humidity followed by short- and mid-term rehydration. We tested the capacity of the algae to recover from desiccation using the effective quantum yield of photosystem II as a proxy for physiological activity. The degree of recovery was dependent both on the habitat of origin and the desiccation scenario, with terrestrial, but not aquatic species, recovering from desiccation. Distinct strains of each species responded similarly to desiccation and rehydration, with the exception of one aquatic strain that recovered from the mildest desiccation. Cell ultrastructure was uniformly maintained in both aquatic and desert species during dehydration and rehydration, but staining with an amphiphilic styryl dye indicated desiccation-induced damage to the plasma membrane in the aquatic species. These analyses demonstrate that terrestrial Tetradesmus possess the vegetative desiccation tolerance phenotype, making these species ideal for comparative omics studies.

This study identified the genus Coelastrella Chodat, 1922 which was isolated from a sediment sample taken from the Tigris river in Baghdad Governorate, Iraq. The alga was isolated and cultured in modified Chu 10 media and the morphological features of the isolated algae were observed in light microscopy (LM); it showed some characteristic features of this genus, such as its ellipsoidal or lemon- shaped cells, a visible pyrenoid and the chloroplast parietal. To ensure correct identification of the isolated alga, a molecular analysis using 18S rRNA gene and DNA sequencing revealed a match with C. terrestris (Reisigl) Hedewald & N. Hanagata 2002. This species is a new record in Iraq, and has been registered in NCBI under the accession number MH179121.

Many species belonging to the coccoid green algae genus Coelastrella are considered potential candidates for the large-scale production of natural pigments and biofuels. However, little is known ab...

The family Radiococcaceae sensu lato, defined as colonial autospore-producing mucilaginous coccoid green algae, is widespread in terrestrial and freshwater habitats. Three species of Radiococcaceae sensu lato, including two Radiococcus species and one Planktosphaeria species, were described from China by light and electron microscopy. A new species of Planktosphaeria, Planktosphaeria hubeiensis sp. nov. was erected based on morphological comparisons and genetic analyses. Our phylogenetic analyses indicated that Radiococcaceae sensu lato is polyphyletic, and separated into three lineages. The Radiococcus species did not cluster into a monophyletic group in phylogenetic analyses; therefore the taxonomy of the genus Radiococcus should be revised in the future.

α-Linolenic acid (ALA) is an essential fatty acid which cannot be synthesized de novo in mammals and must be ingested regularly in the diet. In this study, a microalgal strain named HDMA-11 was isolated from Lake Ming, China, and was found to accumulate a high ALA content (39.2% of total lipids). Phylogenetic neighbor-joining analysis indicated that HDMA-11 belongs to the genus Monoraphidium (Selenastraceae, Sphaeropleales) and its 18S ribosomal DNA sequence seemed to be a new molecular record of a Monoraphidium species. The fatty acid profiles, biomass productivity and lipid content of HDMA-11 were also investigated in autotrophic conditions. The high levels of polyunsaturated fatty acids in HDMA-11, especially ALA, make it suitable as a source of nutritional supplementation for human health. Furthermore, HDMA-11 exhibited good properties for biodiesel production, characterized by high lipid content (28.5% of dry weight), moderate biomass productivity (31.5 mg L−1 day−1) and a promising lipid profile.

Phytoplanktons were collected from various environments including small marshes, small ponds, reservoirs and brackish water from March 2017 to November 2017. In this study, five species of family Scenedesmaceae were newly recorded in Korea. The genus Desmodesmus was newly reported in Korea. The newly recorded species are Scenedesmus nanus, S. praetervisus, Desmodesmus costato-granulatus, D. lunatus and D. spinulatus. S. nanus and S. praetervisus are known to occur in freshwater, but they were found in the brackish water in this study.

Conventional identification of three coccoid green algae isolates was attempted to characterize the studied algae morphologically under compound microscope, which demonstrated confusional phenomenal convergence; all were classified microscopically as the green alga Chlorella vulgaris Beijerinck, 1890. Phylogenetic studies were conducted to settle the argument about the phenotype by studying the genotype. Genotype the promising field in advance classification by using 18S rRNA and compared to GenBank database using to search the related sequences. The determined sequences showed high a similarity to the strains registered in GenBank. Phylogenetic tree of ITS within 18S RNA were analyzed: the phylogram separated into two clusters, the first cluster included C1-ITS-Iraq and C2-ITS-Iraq and put with Coelastrella Chodat, 1922 which was well supported in bootstrap tests (86-100%), while the second cluster included C3-ITS-Iraq and put with C. sorokiniana Shihira and Krauss, 1965, which have bootstrap value 100% with the mentioned species. however, in this study, the green alga Colestrella was identified as new record genus in Iraqi freshwater belonged to the order Sphaeropleales.

PREMISE OF THE STUDY Phylogenomic analyses across the green algae are resolving relationships at the class, order, and family levels and highlighting dynamic patterns of evolution in organellar genomes. Here we present a within-family phylogenomic study to resolve genera and species relationships in the family Hydrodictyaceae (Chlorophyceae), for which poor resolution in previous phylogenetic studies, along with divergent morphological traits, have precluded taxonomic revisions. METHODS Complete plastome sequences and mitochondrial protein-coding gene sequences were acquired from representatives of the Hydrodictyaceae using next-generation sequencing methods. Plastomes were characterized, and gene order and content were compared with plastomes spanning the Sphaeropleales. Single-gene and concatenated-gene phylogenetic analyses of plastid and mitochondrial genes were performed. KEY RESULTS The Hydrodictyaceae contain the largest sphaeroplealean plastomes thus far fully sequenced. Conservation of plastome gene order within Hydrodictyaceae is striking compared with more dynamic patterns revealed across Sphaeropleales. Phylogenetic analyses resolve Hydrodictyon sister to a monophyletic Pediastrum, though the morphologically distinct P. angulosum and P. duplex continue to be polyphyletic. Analyses of plastid data supported the neochloridacean genus Chlorotetraedron as sister to Hydrodictyaceae, while conflicting signal was found in the mitochondrial data. CONCLUSIONS A phylogenomic approach resolved within-family relationships not obtainable with previous phylogenetic analyses. Denser taxon sampling across Sphaeropleales is necessary to capture patterns in plastome evolution, and further taxa and studies are needed to fully resolve the sister lineage to Hydrodictyaceae and polyphyly of Pediastrum angulosum and P. duplex.

The revision of the serie Desmodesmus, based on light microscopy, TEM, SEM and ITS2r DNA, allowed us to distinguish among the taxa Desmodesmus communis var. communis, var. polisicus, D. curvatocornis, D. rectangularis comb. nov., D. pseudocommunis n. sp. var. texanus n. var. and f. verrucosus n. f., D. protuberans, D. protuberans var. communoides var. nov., D. pseudoprotuberans n. sp., D. schmidtii n. sp. Keys were given for light microscopy, electron microscopy and ITS2r DNA.

Background Terrestrial, freshwater and marine green algae constitute the large and morphologically diverse phylum of Chlorophyta, which gave rise to the core chlorophytes. Chlorophyta are abundant and diverse in freshwater environments where sometimes they form nuisance blooms under eutrophication conditions. The phylogenetic relationships among core chlorophyte clades (Chlorodendrophyceae, Ulvophyceae, Trebouxiophyceae and Chlorophyceae), are of particular interest as it is a species-rich phylum with ecological importance worldwide, but are still poorly understood. In the Mediterranean ecoregion, data on molecular characterization of eukaryotic microalgae strains are limited and current knowledge is based on ecological studies of natural populations. In the present study we report the isolation and characterization of 11 green microalgae strains from Greece contributing more information for the taxonomy of Chlorophyta. The study combined morphological and molecular data. Results Phylogenetic analysis based on 18S rRNA, internal transcribed spacer (ITS) region and the large subunit of the ribulose-bisphosphate carboxylase (rbcL) gene revealed eight taxa. Eleven green algae strains were classified in four orders (Sphaeropleales, Chlorellales, Chlamydomonadales and Chaetophorales) and were represented by four genera; one strain was not assigned to any genus. Most strains (six) were classified to the genus Desmodesmus, two strains to genus Chlorella, one to genus Spongiosarcinopsis and one filamentous strain to genus Uronema. One strain is placed in a separate independent branch within the Chlamydomonadales and deserves further research. Conclusions Our study reports, for the first time, the presence of Uronema in an aquatic environment up to 40 °C and reveals new diversity within the Chlamydomonadales. The results from the ITS region and the rbcL gene corroborated those obtained from 18S rRNA without providing further information or resolving the phylogenetic relationships within certain genera, due to the limited number of ITS and rbcL sequences available. The comparison of molecular and morphological data showed that they were congruent. Cosmopolitan genera with high worldwide distribution inhabit Greek freshwaters.

Hariotina reticulata P. A. Dangeard 1889 (Sphaeropleales, Chlorophyta) is a common member of the summer phytoplankton of meso- to highly eutrophic water bodies with a worldwide distribution. Here, we report the draft whole-genome shotgun sequencing of H. reticulata strain SAG 8.81. The final assembly comprises 107,596,510bp with over 15,219 scaffolds (>100bp). This whole-genome project is publicly available in the CNSA (https://db.cngb.org/cnsa/) of CNGBdb under the accession number CNP0000705.

Mitochondria of diverse eukaryotes have evolved various departures from the standard genetic code, but the breadth of possible modifications and their phylogenetic distribution are known only incompletely. Furthermore, it is possible that some codon reassignments in previously sequenced mitogenomes have been missed, resulting in inaccurate protein sequences in databases. Here we show, considering the distribution of codons at conserved amino acid positions in mitogenome-encoded proteins, that mitochondria of the green algal order Sphaeropleales exhibit a diversity of codon reassignments, including previously missed ones and some that are unprecedented in any translation system examined so far, necessitating redefinition of existing translation tables and creating at least seven new ones. We resolve a previous controversy concerning the meaning the UAG codon in Hydrodictyaceae, which beyond any doubt encodes alanine. We further demonstrate that AGG, sometimes together with AGA, encodes alanine instead of arginine in diverse sphaeroplealeans. Further newly detected changes include Arg-to-Met reassignment of the AGG codon and Arg-to-Leu reassignment of the CGG codon in particular species. Analysis of tRNAs specified by sphaeroplealean mitogenomes provides direct support for and molecular underpinning of the proposed reassignments. Furthermore, we point to unique mutations in the mitochondrial release factor mtRF1a that correlate with changes in the use of termination codons in Sphaeropleales, including the two independent stop-to-sense UAG reassignments, the reintroduction of UGA in some Scenedesmaceae, and the sense-to-stop reassignment of UCA widespread in the group. Codon disappearance seems to be the main drive of the dynamic evolution of the mitochondrial genetic code in Sphaeropleales.

Mitochondria of diverse eukaryotes have evolved various departures from the standard genetic code, but the breadth of possible modifications and their phylogenetic distribution are known only incompletely. Furthermore, it is possible that some codon reassignments in previously sequenced mitogenomes have been missed, resulting in inaccurate protein sequences in databases. Here we show, considering the distribution of codons at conserved amino acid positions in mitogenome-encoded proteins, that mitochondria of the green algal order Sphaeropleales exhibit a diversity of codon reassignments, including previously missed ones and some that are unprecedented in any translation system examined so far, necessitating redefinition of existing translation tables and creating at least seven new ones. We resolve a previous controversy concerning the meaning the UAG codon in Hydrodictyaceae, which beyond any doubt encodes alanine. We further demonstrate that AGG, sometimes together with AGA, encodes alanine instead of arginine in diverse sphaeroplealeans. Further newly detected changes include Arg-to-Met reassignment of the AGG codon and Arg-to-Leu reassignment of the CGG codon in particular species. Analysis of tRNAs specified by sphaeroplealean mitogenomes provides direct support for and molecular underpinning of the proposed reassignments. Furthermore, we point to unique mutations in the mitochondrial release factor mtRF1a that correlate with changes in the use of termination codons in Sphaeropleales, including the two independent stop-to-sense UAG reassignments, the reintroduction of UGA in some Scenedesmaceae, and the sense-to-stop reassignment of UCA widespread in the group. Codon disappearance seems to be the main drive of the dynamic evolution of the mitochondrial genetic code in Sphaeropleales.

Lanceola loveni grossipes Shoemaker (Fig. 1C, D) Lanceola loveni grossipes Shoemaker, 1945: 209, fig. 16 g, h. Vinogradov 1957: 191; 1960a: 206. Vinogradov et al. 1982: 63–64, fig. 12. Type material. Shoemaker (1945) described this variety from eight specimens collected near Bermuda, at depths between 600 and 1000 fathoms. He states that “the length of the type female is 29 mm ”. The USNM has three female specimens, the type (109450) and two paratypes (109451 & 2). The whereabouts of the other five specimens is unknown. Material examined. Types. Holotype female (USNM 109450) and two paratype females (USNM 109451 & 2) from the North Atlantic, near Bermuda [32º12’N 52º36’W]; William Beebe Oceanographic Expedition, col. 7 Sept. 1931, 22 Jun. 1929 & 30 Jun. 1930 respectively: in spirit. Other material examined. Female 25 mm, semi-mature (SAMA C6252), N. E. Pacific, off Alexander Archipelago, British Columbia [53º59’N 138º46.12’W]; ex M. Galbraith, 250– 150m, 26 Sept. 2001. Diagnosis. Like typical form except for the following. Length of sexually mature females 27–30 mm. Pereopod 6 is relatively longer with propodus expanded distally into rounded club-shape, housing retractile dactylus. Pereopod 7 is slightly shorter than half-length P6. Remarks. Described as a mere variety of L. loveni by Shoemaker (1945) it was elevated to sub-specific rank by Vinogradov et al. (1982) and according to them the features characteristic of L. loveni grossipes are only exhibited by sexually mature females. Distribution. This subspecies has been recorded from the North Atlantic, near Bermuda [32º12’N 52º36’W] by Shoemaker (1945); the North–west Pacific, S.E. of Japan [30º52’N 153º16’E & 30º53’N 153º09’E] by Vinogradov (1957 & 1960a) and N.E. of Marshall Is [16º08’N 173º10’E] by Vinogradov (1960a). The SAMA specimen (Fig. 1) is the first record from the North-east Pacific., Published as part of Zeidler, Wolfgang, 2009, A review of the hyperiidean amphipod superfamily Lanceoloidea Bowman & Gruner, 1973 (Crustacea: Amphipoda: Hyperiidea), pp. 1-117 in Zootaxa 2000 on page 16, {"references":["Shoemaker, C. R. (1945) The Amphipoda of the Bermuda Oceanographic Expeditions, 1929 - 1931. Zoologica, New York, 30, 185 - 266.","Vinogradov, M. E. (1957) Hyperiids (Amphipoda) of the Northwest Pacific Ocean. 1. Tribe Hyperiidea Physosomata. Trudy Instituta Okeanologii Akademiya Nauk SSSR 20: 186 - 227. [In Russian]. English translation by American Institute of Biological Sciences, Washington D. C., 1959, Marine Biology, 149 - 184.","Vinogradov, M. E. (1960 a) Hyperiidea Physosomata of the Tropical Pacific Ocean. Trudy Instituta Okeanologii Akademiya Nauk SSSR 41, 198 - 247. [In Russian].","Vinogradov, M. E., Volkov, A. F. & Semenova, T. N. (1982) Amfipody-Giperiidy (Amphipoda: Hyperiidea) Mirovogo Okeanea. Akademiya Nauk SSSR, Opredeliteli po Faune SSSR No. 132. Leningrad, 492 pp. [In Russian]. English translation, 1996, Smithsonian Institution Libraries, Washington D. C., D. Siegel-Causey, Scientific Editor."]}

Genetic code deviations involving stop codons have been previously reported in mitochondrial genomes of several green plants (Viridiplantae), most notably chlorophyte algae (Chlorophyta). However, as changes in codon recognition from one amino acid to another are more difficult to infer, such changes might have gone unnoticed in particular lineages with high evolutionary rates that are otherwise prone to codon reassignments. To gain further insight into the evolution of the mitochondrial genetic code in green plants, we have conducted an in-depth study across mtDNAs from 51 green plants (32 chlorophytes and 19 streptophytes). Besides confirming known stop-to-sense reassignments, our study documents the first cases of sense-to-sense codon reassignments in Chlorophyta mtDNAs. In several Sphaeropleales, we report the decoding of AGG codons (normally arginine) as alanine, by tRNA(CCU) of various origins that carry the recognition signature for alanine tRNA synthetase. In Chromochloris, we identify tRNA variants decoding AGG as methionine and the synonymous codon CGG as leucine. Finally, we find strong evidence supporting the decoding of AUA codons (normally isoleucine) as methionine in Pycnococcus. Our results rely on a recently developed conceptual framework (CoreTracker) that predicts codon reassignments based on the disparity between DNA sequence (codons) and the derived protein sequence. These predictions are then validated by an evaluation of tRNA phylogeny, to identify the evolution of new tRNAs via gene duplication and loss, and structural modifications that lead to the assignment of new tRNA identities and a change in the genetic code.

The aim of this study was to assess the phylogenetic relationships, ecology and ecophysiological characteristics of the dominant planktic algae in ice-covered lakes on James Ross Island (northeastern Antarctic Peninsula). Phylogenetic analyses of 18S rDNA together with analysis of ITS2 rDNA secondary structure and cell morphology revealed that the two strains belong to one species of the genus Monoraphidium (Chlorophyta, Sphaeropleales, Selenastraceae) that should be described as new in future. Immotile green algae are thus apparently capable to become the dominant primary producer in the extreme environment of Antarctic lakes with extensive ice-cover. The strains grew in a wide temperature range, but the growth was inhibited at temperatures above 20 °C, indicating their adaptation to low temperature. Preferences for low irradiances reflected the light conditions in their original habitat. Together with relatively high growth rates (0.4–0.5 day−1) and unprecedently high content of polyunsaturated fatty acids (PUFA, more than 70% of total fatty acids), it makes these isolates interesting candidates for biotechnological applications.

Cette etude fournit de nouvelles connaissances sur les preferences ecologiques Pediastrum, plus c´est la premiere description detaillee des populations naturelles et des cultures au Mexique. Elle fournit des informations sur l'ultrastructure et les conditions environnementales de Pediastrum sensu lato dans en endroits dans le centre du pays. Ce genre (Hydrodictyaceae, Chlorophyceae) n'a pas une origine monophyletique plutot a ete divise en cinq genres : Lacunastrum, Monactinus, Parapediastrum, Pseudopediastrum et Stauridium. Les specimens etudies ont ete recueillies entre Octobre 2009 et Novembre 2013. Les microscopes optique et electronique ont revele la presence de sept especes. Parmi cellesci, Monactinus simplex, Pediastrum duplex, Pseudopediastrum boryanum et Stauridium tetras ont une distribution dans le monde entier. Au lieu de cela, Monactinus simplex var. echinulatum, M. simplex var. sturmii et Pediastrum simplex var. clathratum ont ete enregistrees comme des taxa rares. La distribution des especes en examinant la litterature de 1841–2015 a signale l'existence de 23 taxa dans 17 etats du Mexique, ou les etats de Mexique, Veracruz et Michoacan avec plusieurs especes. L'analyse Canonicale des Correspondances a montre que les relations entre les especes et les conditions environnementales des taxons rares sont liees a des temperatures elevees, des sites bien oxygenes et des conditions eutrophes.This study gives new insights into ecological preferences of the Pediastrum genus as well as the first detailed description of its natural populations and cultures in Mexico. This artile provides information on the ultrastructure and environmental conditions of Pediastrum sensu lato at six locations in the center of Mexico. This genus (Hydrodictyaceae, Chlorophyceae) does not have a monophyletic origin; rather, it has been divided into the following five genera: Lacunastrum, Monactinus, Parapediastrum, Pseudopediastrum and Stauridium. The study specimens were collected between October 2009 and November 2013. Light and scanning electron microscopy revealed the presence of seven species. Of these, Monactinus simplex, Pediastrum duplex, Pseudopediastrum boryanum and Stauridium tetras have worldwide distribution. By contrast, Monactinus simplex var. echinulatum, M. simplex var. sturmii and Pediastrum simplex var. clathratum were found to be rare taxa. The species distribution as determined by literature review of articles from 1841 to 2015 registered the presence of 23 taxa in 17 Mexican states, namely, Mexico City, Veracruz and Michoacan which were the sites with the largest numbers of species. Canonical correspondence analyses showed that the relationships between the species and the environmental conditions of the rare taxa are related to well-oxygenated, high temperature and eutrophic conditions.

This article focuses on a detailed morphological and molecular analysis of the microscopic green alga Pediastrum alternans as it exhibits ambiguous morphology, questionable phylogenetic position and scattered distribution. The species, originally described from lakes close to the Baltic Sea in Denmark, was recently renamed Pseudopediastrum alternans based on rDNA sequencing of one culture from Namibia. In the present study, the African culture was morphologically and genetically compared with a culture identified as Ps. alternans from a coastal lake from northern Poland and a culture of Ps. boryanum var. longicorne from southern Poland. Conventional measurements, statistical and geometric morphometric analyses of the number of cells in coenobia, cell shape and size and wall ornamentation showed significant differences in the morphology of the three cultures. The analyses supported the phylogenetic distinction of the cultures based on rDNA and chloroplast DNA sequencing. Cultures of Pseudopediast...

Chloroplast sequence data are widely used to infer phylogenies of plants and algae. With the increasing availability of complete chloroplast genome sequences, the opportunity arises to resolve ancient divergences that were heretofore problematic. On the flip side, properly analyzing large multi-gene data sets can be a major challenge, as these data may be riddled with systematic biases and conflicting signals. Our study contributes new data from nine complete and four fragmentary chloroplast genome sequences across the green algal order Sphaeropleales. Our phylogenetic analyses of a 56-gene data set show that analyzing these data on a nucleotide level yields a well-supported phylogeny - yet one that is quite different from a corresponding amino acid analysis. We offer some possible explanations for this conflict through a range of analyses of modified data sets. In addition, we characterize the newly sequenced genomes in terms of their structure and content, thereby further contributing to the knowledge of chloroplast genome evolution.

We characterized the complete sequence of the mitochondrial genome of the freshwater green algal strain YC001, known as ‘Ettlia sp.', which is of great interest for biofuel production. The size of the mitogenome was 52,489 base pairs (bp), with 49.0% GC content. It consisted of 49 mitochondrial genes typical of the Chlorophyceae, including 16 protein-coding genes, 27 transfer RNA genes and six ribosomal RNA genes as well as three introns within cox1 (6832 bp), rnl4 (1805 bp) and cob (1107 bp). We determined that YC001 is a species of Coelastrella on the basis of molecular phylogenetic analyses and microscopic observations. A unique feature of this mitogenome is the presence of three different types of inverted repeats between trnL and trnI and between nad4 and cox1 as well as the presence of orf215, orf755 and one additional copy of the trnM gene, all of which enable a comparison with an available sister taxon, Acutodesmus obliquus.

Asterarcys is a resilient microalgal species which can sustain high light intensities and have high biomass and lipid productivity under mixotrophy. These attributes make it a potential candidate to produce biodiesel and biofuels. However, no genetic information is currently available for this species. Here, we report the chloroplast genome sequence of Asterarcys sp. and compare it with the chloroplast genome of closely related chlorophyceaen microalgae. The chloroplast genome of Asterarcys sp. is present as a ~111 kb circular molecule with 88 genes and a coding density of 50.28%. The 111,776 bp genome shows a quadripartite structure with two 6297 bp long inverted repeats separating single copy regions (SSC) of almost equal sizes. The small and compact genome of Asterarcys shows similarity in gene structure and organization with that of its closest relative Scenedesmus obliquus. It reinforces the compact nature of chloroplast genomes of Sphaeropleales as compared to that of inflated genomes in Chlamydomonadales. The genome shows a biased distribution of genes with 50 of the protein-coding genes encoded from one strand and 15 from the opposite strand. This biased distribution of genes is likewise to that of Scenedesmus obliquus. The phylogenetic tree based on protein-coding genes from chlorophycean species places Asterarcys close to Scenedesmus. The chloroplast genome information of Asterarcys will help understand the phylogeny of Sphaeropleales and Chlorophyceae. In the present study, we also report a simple and effective method for isolation of Asterarcys sp. chloroplast DNA of high quality and purity which is an essential prerequisite for efficient genome sequencing.

Background Chlorophyceae is one of three most species-rich green algal classes and also the only class in core Chlorophyta whose monophyly remains uncontested as gene and taxon sampling improves. However, some key relationships within Chlorophyceae are less clear-cut and warrant further investigation. The present study combined genome-scale chloroplast data and rich sampling in an attempt to resolve the ordinal classification in Chlorophyceae. The traditional division into Sphaeropleales and Volvocales (SV), and a clade containing Oedogoniales, Chaetopeltidales, and Chaetophorales (OCC) was of particular interest with the addition of deeply branching members of these groups, as well as the placement of several incertae sedis taxa. Methods We sequenced 18 chloroplast genomes across Chlorophyceae to compile a data set of 58 protein-coding genes of a total of 68 chlorophycean taxa. We analyzed the concatenated nucleotide and amino acid datasets in the Bayesian and Maximum Likelihood frameworks, supplemented by analyses to examine potential discordant signal among genes. We also examined gene presence and absence data across Chlorophyceae. Results Concatenated analyses yielded at least two well-supported phylogenies: nucleotide data supported the traditional classification with the inclusion of the enigmatic Treubarinia into Sphaeropleales sensu lato. However, amino acid data yielded equally strong support for Sphaeropleaceae as sister to Volvocales, with the rest of the taxa traditionally classified in Sphaeropleales in a separate clade, and Treubarinia as sister to all of the above. Single-gene and other supplementary analyses indicated that the data have low phylogenetic signal at these critical nodes. Major clades were supported by genomic structural features such as gene losses and trans-spliced intron insertions in the plastome. Discussion While the sequence and gene order data support the deep split between the SV and OCC lineages, multiple phylogenetic hypotheses are possible for Sphaeropleales s.l. Given this uncertainty as well as the higher-taxonomic disorder seen in other algal groups, dwelling on well-defined, strongly supported Linnaean orders is not currently practical in Chlorophyceae and a less formal clade system may be more useful in the foreseeable future. For example, we identify two strongly and unequivocally supported clades: Treubarinia and Scenedesminia, as well as other smaller groups that could serve a practical purpose as named clades. This system does not preclude future establishment of new orders, or emendment of the current ordinal classification if new data support such conclusions.

Earlier and more recent history of the relationship between the desmid genera Acutodesmus and Tetradesmus (Sphaeropleales, Chlorophyta) is discussed. It is pointed out that current taxonomic treatments are using the name Acutodesmus (Hegewald) Tsarenko, which dates as a genus only from 2001. Taxonomic treatments are now including in Acutodesmus A. wisconsinensis, which is the type species of the earlier generic name Tetradesmus of G. M. Smith (1913). Because of the priority of Tetradesmus, ten taxa are transferred to that genus. (© 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

The family Selenastraceae includes many species of freshwater green microalgae with morphological characteristics that are so subtly different that it is difficult to discriminate species within it. Therefore, the use of the diacritical characteristics of traditional morphological taxonomy may be ineffective at differentiating among many species of the family. Chemotaxonomy based on fatty acid methyl ester (FAME) can help resolve uncertainties not completely addressed by other approaches, such as molecular studies of some species within the Selenastraceae. Here, we first tested three techniques for the analysis of microalgal FAME to choose the one that would provide the best profiles for chemotaxonomy: 1) direct transesterification (DT) of the biomass followed by gas chromatography coupled to mass spectrometry analysis (GC-MS); 2) extraction using chloroform and methanol, followed by transesterification (T) and then analysis by gas chromatography/flame ionization detector (GC-FID); and 3) extraction with chloroform and methanol and then separation into lipid classes using thin-layer chromatography (TLC) using the Iatroscan-Chromarod system. The tests were conducted on 12 strains (11 species) of Selenastraceae and one outgroup strain. The fatty acid profiles produced by the DT-GC-MS technique yielded the best results for the chemotaxonomy of the Selenastraceae species using 12 FAME. The proportion of the variance in the fatty acid profiles obtained with DT-GC-MS analysis explained by species was 85%, whereas the differences explained by strains was 92%. Therefore, DT-GC-MS was used to analyze other microalgae strains, totaling 15 species of 8 genera of green coccoid microalgae, including the recently described Curvastrum. The results with all strains showed that fatty acid profiles obtained by DT-GC-MS were significantly different (p 0.001) among strains and among species. The variance in fatty acids profiles explained by separation into strains was 97%, whereas the separation into species explained 93% of the variance. Statistical analyses showed that, for our dataset, the C

In this study, the chloroplast genome of Hariotina reticulata was fully sequenced and compared to other Sphaeropleales chloroplast genomes. It is 210,757 bp larger than most Sphaeropleales cpDNAs. It presents a traditional chloroplast structure, and contains 103 genes, including 68 protein-coding genes, six rRNA genes and 29 tRNA genes. The coding region constitutes of 43% of the whole cpDNA. Eighteen introns are found in 11 genes and six introns are unique for Hariotina. 11 open reading frames are identified among these introns. The synteny between Hariotina and Acutodesmus cpDNAs is in general identical, while within Sphaeropleales order, high variability in cpDNA architecture is indicated by general high DCJ distances. Ankyra judayi exhibits the greatest dissimilarity in gene synteny to the others and share some unique gene clusters with Treubaria triappendiculata. The phylogenomic analyses show that A. judayi is clustered with Treubariaceae species and sister to Chlorophyceae incertae sedis and other Sphaeropleales species. The monophyly of Sphaeropleales is rejected.

The majority of our knowledge about mitochondrial genomes of Viridiplantae comes from land plants, but much less is known about their green algal relatives. In the green algal order Sphaeropleales (Chlorophyta), only one representative mitochondrial genome is currently available-that of Acutodesmus obliquus. Our study adds nine completely sequenced and three partially sequenced mitochondrial genomes spanning the phylogenetic diversity of Sphaeropleales. We show not only a size range of 25-53 kb and variation in intron content (0-11) and gene order but also conservation of 13 core respiratory genes and fragmented ribosomal RNA genes. We also report an unusual case of gene arrangement convergence in Neochloris aquatica, where the two rns fragments were secondarily placed in close proximity. Finally, we report the unprecedented usage of UCG as stop codon in Pseudomuriella schumacherensis. In addition, phylogenetic analyses of the mitochondrial protein-coding genes yield a fully resolved, well-supported phylogeny, showing promise for addressing systematic challenges in green algae.

The development of efficient algae cryopreservation methods is pivotal to the establishment of long-term culture collections as well as algae breeding and genetic modification programs. However, the unpredictable responses of distinct algal species to cryopreservation agents and protocols have hampered the standardization of universal methods so far. The results presented in this study indicate that intrinsic biological factors (i.e.: cell morphology and phylogenetic origin) play a role in the definition of which culture age and cryoprotectant agent type and concentration should be used to achieve successful cryopreservation. Through the use of Central Composite Rotatable Design (CCRD) it was possible to define optimized protocols for cryopreserving three major morphotypic groups found among chlorophytes (i.e.: coenobium, coccoid or palmella forming strains). These optimized protocols were then validated upon fifteen strains from Sphaeropleales, Chlamydomonadales and Chlorelalles clades. Analysis reveals that the use of DMSO as the sole cryoprotectant provided the highest post-freezing cell viability recovery rates for 80% of the coccoid strains tested, while the combination of glycerol and PEG400 allowed efficient cryopreservation of 100% of the coenobium and palmella forming strains evaluated. In addition, results suggest that coenobium-forming strains have higher resistance to freeze/thawing when frozen at mid-log phase of growth, while coccoid and plamelloid strains present higher survival rates when cryopreserved at late-log phase. Such information is of valuable practical use since a simple visual inspection of algae strain's predominant morphotype can guide the choice of the most suitable cryopreservation protocol.