Morphological and phylogenetic relations of members of the genus Coelastrella (Scenedesmaceae, Chlorophyta) from the Ural and Khentii Mountains (Russia, Mongolia)

We describe the morphological features and the phylogenetic relationships of five morphologically similar strains belonging to the genus Coelastrella, which live in different ecological and geographical conditions of terrestrial ecosystems: in the Ural Mountains (Polar, Subpolar, and Northern Urals of Russia) and the Khentii Mountains (Russia and Mongolia). We analysed algal strains stored in the Culture Collection of Algae of the Institute of Biology, Syktyvkar, Russia (SYKOA Ch-045-09, SYKOA Ch-047-11, SYKOA Ch-072-17) and the Culture Collection of Algae at Herbarium of the Siberian Institute of Plant Physiology and Biochemistry, Irkutsk, Russia (IRK-A 2, IRK-A 173). By light microscopy, all samples were assigned to Coelastrella terrestris. However, the phylogenetic analyses based on the nucleotide sequences of 18S rDNA and ITS1-ITS2 showed that only one strain belongs to C. terrestris (IRK-A 173). Other samples were closer to C. oocystiformis (SYKOA Ch-045-09; IRK-A 2) and C. aeroterrestrica (SYKOA Ch-047-11). The strain SYKOA Ch-072-17 is probably a new species for the genus. These results confirmed the high phenotypic variability and the hidden diversity among the members of this green algal group.

PHARMACEUTICAL POTENTIAL OF LABORATORY GROWN CULTURES OF BLUE-GREEN ALGAE: A COMPREHENSIVE REVIEW AND FUTURE POSSIBILITIES

COVID-19 pandemic has taught the world researchers the urgent need for new sources and novel pharmaceuticals not only for existing diseases but also for both seasonal epidemics and future pandemics. Pharmaceutical drug discoveries for the past fifty years depended deeply on the procedure of empirical transmission of a huge number of pure bioactive compounds to provide new leads. The screening of extracts or isolating compounds is a common way to discover novel biologically active molecules. Most of the valuable Blue-Green algal metabolites are concentrated in their biomass. For existence in nature, Blue-Green algae (BGA) secrete and contain various organic substances like proteins, fatty acids, vitamins, pigments, primary and secondary metabolites, and these compounds are explored for potential biological activities such as antibacterial, antifungal, antiviral (including the anti-SARS-CoV-2 virus that causes COVID-19), anticancer, antioxidant, antidiabetic, protease inhibitory activity, anti-inflammatory activity, etc. Due to their diverse application, pharmaceutical companies have shown commercial interest in the Blue-green algal group for the discovery and development of novel molecules to combat deadly diseases for the benefit of society and mankind. The current review paper highlights and discusses the diverse pharmaceutical potential of laboratory-grown cultures of BGA along with comprehensive and current knowledge on bioactive compounds discovered by researchers globally.

Cytometric Analysis of Diverse Glaucophyte Species Reveals Distinctive Signals Useful for Fluorescence-Based Detection and Sorting

Glaucophytes, red algae and viridiplants (green algae and land plants) are formally united in the supergroup Archaeplastida. Although diverse molecular and genomic evidence suggest the common origin of the three Archaeplastida lineages, the lack of a robust glaucophyte knowledgebase has limited comprehensive evaluations of competing hypotheses. Glaucophytes are rare and apparently confined to freshwater habitats. However, the distribution and diversity of these algae have not been thoroughly explored owing to challenges with detecting and isolating novel specimens. Here we examined the cytometric signatures of representative species of the genera Cyanophora, Cyanoptyche, Glaucocystis and Gloeochaete for a distinctive signal that would aid identification. Most glaucophytes analyzed presented a relatively high red fluorescence signal due to the presence of the blue phycobiliproteins C-phycocyanin and allophycocyanin. Cell-size differences and the concurrent presence of the red phycobiliprotein phycoerythrin in other algal lineages, such as red algae and cryptophytes, allowed us to distinguish glaucophytes from other photosynthetic cells containing blue phycobiliproteins. We used fluorescence-assisted cell sorting (FACS) to isolate viable Cyanophora and Glaucocystis individuals from existing cultures. Our results indicate that the peculiar autofluorescence signal of glaucophytes will facilitate further identification and isolation on novel specimens of this scarce but important algal group.

Transparent Exopolymer Particles (TEP), phytoplankton and picocyanobacteria a littoral-to-pelagic depth-gradient in a large subalpine lake

Transparent Exopolymer Particles (TEP) play an important role in the organic carbon cycle of many aquatic systems but the production and distribution of TEP have been studied mainly in the marine environment, neglecting the large oligotrophic lakes. We selected Lake Maggiore, one of the most important freshwater reserve in Northern Italy, to study the horizontal and vertical distribution of TEP and of its possible drivers. Samplings along a transect in the Borromeo basin were performed in May, July and September 2019. Total Organic Carbon (TOC), TEP, chlorophyll-a (Chl) of different algal groups, picocyanobacteria, bacteria and eukaryotes counting, were measured at six stations and five depths. Our study showed that TEP exhibited a clear vertical heterogeneity from surface to the bottom related to the autotrophic microorganisms that are the main source of TEP and are prevalent in the euphotic zone of the lake. On the other hand, TEP was fairly evenly distributed along the horizontal transect from littoral to pelagic zone, although patches were present in spring, when TEP concentrations were low. In contrast to TEP, TOC and to a lesser extent Chl and bacteria showed horizontal heterogeneity, in some months. In Lake Maggiore TEP indeed was an important fraction of Total Organic Carbon (TOC), making up to 54% of TOC (in carbon units: 910 µg C L-1) and it was significantly correlated with Chl. The highest TEP concentration (1.44 mg GX eq L-1) was measured in September 2019, in coincidence with an episode of superficial foam appearance. Considering the biomass as Chl concentrations, the algal group mostly related to TEP was that of brown algae, particularly diatoms; but considering the numbers, the picocyanobacteria and bacteria were more significantly correlated to TEP. The presence of pennate diatoms in May and July, with their TEP-related chlorophyll, did not produce TEP in as high concentration as that observed in September in the presence of centric diatoms and of very high numbers of picocyanobacteria and bacteria.

Integrative Taxonomic, Ecological and Genotyping Study of Charophyte Populations from the Egyptian Western-Desert Oases and Sinai Peninsula

Present-day information available on the charophyte macroalgae in Egypt, including their phylogenetic affinities, remains largely incomplete. In this study, nine charophyte populations were collected from different aquatic biotopes across the Egyptian Western-Desert Oases and Sinai Peninsula. All populations were investigated using an integrative polyphasic approach including phylogenetic analyses inferred from the chloroplast-encoded gene (rbcL) and the internal transcribed spacer (ITS1) regions, in parallel with morphotaxonomic assignment, ultrastructure of the oospore walls, and autecology. The specimens identified belonged to the genera Chara, Nitella, and Tolypella, with predominance of the first genus to which five species were assigned though they presented some interesting aberrant taxonomic features: C. aspera, C. contraria, C. globata, C. tomentosa, and C. vulgaris. Based on our integrative study, the globally rare species C. globata was reported for the second time for the whole African continent. The genus Nitella was only represented by N. flagellifera, and based on the available literature, it is a new record for North Africa. Noteworthy, an interesting Tolypella sp., morphologically very similar to T. glomerata, was collected and characterized and finally designated with the working name ‘Tolypella sp. PBA–1704 from a desert, freshwater wetland’, mainly based on its concatenated rbcL+ITS1 phylogenetic position. This study not only improved our understanding on the diversity, biogeography and autecological preferences of charophytes in Egypt, but it also broadened our knowledge on this vulnerable algal group in North Africa, emphasizing the need of more in-depth research work in the future, particularly in the less–impacted desert habitats.

Re-examination of two diatom reference genomes using long-read sequencing

Background The marine diatoms Thalassiosira pseudonana and Phaeodactylum tricornutum are valuable model organisms for exploring the evolution, diversity and ecology of this important algal group. Their reference genomes, published in 2004 and 2008, respectively, were the product of traditional Sanger sequencing. In the case of T. pseudonana, optical restriction site mapping was employed to further clarify and contextualize chromosome-level scaffolds. While both genomes are considered highly accurate and reasonably contiguous, they still contain many unresolved regions and unordered/unlinked scaffolds. Results We have used Oxford Nanopore Technologies long-read sequencing to update and validate the quality and contiguity of the T. pseudonana and P. tricornutum genomes. Fine-scale assessment of our long-read derived genome assemblies allowed us to resolve previously uncertain genomic regions, further characterize complex structural variation, and re-evaluate the repetitive DNA content of both genomes. We also identified 1862 previously undescribed genes in T. pseudonana. In P. tricornutum, we used transposable element detection software to identify 33 novel copia-type LTR-RT insertions, indicating ongoing activity and rapid expansion of this superfamily as the organism continues to be maintained in culture. Finally, Bionano optical mapping of P. tricornutum chromosomes was combined with long-read sequence data to explore the potential of long-read sequencing and optical mapping for resolving haplotypes. Conclusion Despite its potential to yield highly contiguous scaffolds, long-read sequencing is not a panacea. Even for relatively small nuclear genomes such as those investigated herein, repetitive DNA sequences cause problems for current genome assembly algorithms. Determining whether a long-read derived genomic assembly is ‘better’ than one produced using traditional sequence data is not straightforward. Our revised reference genomes for P. tricornutum and T. pseudonana nevertheless provide additional insight into the structure and evolution of both genomes, thereby providing a more robust foundation for future diatom research.

Temporal and spatial variability of terrestrial diatoms at the catchment scale: controls on productivity and comparison with other soil algae

Terrestrial diatoms are an integral component of the soil microbial community. However, their productivity and how it compares to other algal groups remains poorly known. This lack of knowledge hampers their potential use as environmental markers in various applications. As a way forward, we investigated the seasonal and spatial patterns of diatom assemblages and the role of environmental factors on the soil diatom productivity. We collected soil algal samples in 16 sites across the Attert River basin (Luxembourg) every 4 weeks for a period of 12 months. The algal abundances were then derived from pigment analysis using High-Performance Liquid Chromatography. Our results indicate that diatom productivity is mainly controlled by factors related to soil moisture availability leading to seasonal patterns, whereas the concentration of green algae remained stable over the course of the study period. Generally, anthropic disturbed habitats contained less living diatom cells than undisturbed habitats. Also, we learned that diatoms can be the dominant algal group at periods of the year with high soil moisture.

Effect of Marine Macroalga Enteromorpha sp. Enriched with Zn(II) and Cu(II) ions on the Digestibility, Meat Quality and Carcass Characteristics of Growing Pigs

In the present study, the effect of macroalga Enteromorpha sp. enriched with Zn(II) and Cu(II) ions on daily amounts of feces and urine excreted by growing pigs, apparent fecal nutrient digestibility and daily nitrogen balance and retention, meat quality and the slaughter value of carcasses was examined. The duration of feeding experiments was 87 days. In the control group, the requirement for zinc and copper was covered by inorganic salts, whereas in the experimental group algae enriched with these elements via biosorption were supplemented. No effect of Enteromorpha sp. on the increase in digestibility of dry matter, dry organic matter, crude protein, crude fat and nitrogen-free extractives was observed. Statistically significant differences concerned only the digestibility of crude ash. The daily amount of excreted feces and urine did not differ significantly between groups. Meat from pigs in the algal group was characterized by a lower water absorption and drip loss and contained less fat and more protein than meat from the control group. Furthermore, a slight darkening of the meat was observed. The weight of the liver was lower in pigs from the algal group. Enriched macroalga Enteromorpha sp. may be introduced into pig nutrition as a feed material as an alternative to inorganic salts.

Water Quality Model Calibration via a Full-Factorial Analysis of Algal Growth Kinetic Parameters

The two-dimensional, laterally-averaged mechanistic eutrophication model CE-QUAL-W2 version 3.72 was used to predict chlorophyll-a concentrations across two different time periods in the Neuse River Estuary, North Carolina. Chlorophyll calibration was performed for two time periods simultaneously by performing a full-factorial experiment that tested seven algal kinetic growth parameters over three levels for a single algal group. A cluster of up to six computers each running between two and ten instances of the program was used to complete and manage the data for 2187 runs for each period. Six numeric criteria were used to determine which runs performed acceptably, yielding a group of 27 cases that met all of the criteria. Calibration performance of the set of cases outperformed a previously calibrated model using three algal groups that met only four of the six selection criteria. Calibration performed this way allowed for a more rational specification of model calibration performance and provided uncertainty estimates of model predictions, albeit at the cost of a considerable increase in computational requirements that necessitated the use of a computer cluster.

Water Quality Model Calibration via a Full-Factorial Analysis of Algal Growth Kinetic Parameters

The two-dimensional, laterally-averaged mechanistic eutrophication model CE-QUAL-W2 version 3.72 was used to predict chlorophyll-a concentrations across two different time periods in the Neuse River Estuary, North Carolina. Chlorophyll calibration was performed for two time periods simultaneously by performing by a full-factorial experiment that tested seven algal kinetic growth parameters over three levels for a single algal group. A cluster of up to six computers each running between two and ten instances of the program was used to complete and manage the data for 2187 runs for each time period. A set of six criteria were used to determine which runs performed acceptably, yielding a group of 27 cases that met all of the criteria. Calibration performance of the set of cases outperformed a previously calibrated model using three algal groups that met only four of the six selection criteria. Calibration performed this way allowed for a more rational specification of model calibration performance and provided uncertainty estimates of model predictions, albeit at the cost of a considerable increase in computational requirements that necessitated the use of a computer cluster.