Evolution and Stress Responses of CLO Genes and Potential Function of the GhCLO06 Gene in Salt Resistance of Cotton

The caleosin (CLO) protein family displays calcium-binding properties and plays an important role in the abiotic stress response. Here, a total of 107 CLO genes were identified in 15 plant species, while no CLO genes were detected in two green algal species. Evolutionary analysis revealed that the CLO gene family may have evolved mainly in terrestrial plants and that biological functional differentiation between species and functional expansion within species have occurred. Of these, 56 CLO genes were identified in four cotton species. Collinearity analysis showed that CLO gene family expansion mainly occurred through segmental duplication and whole-genome duplication in cotton. Sequence alignment and phylogenetic analysis showed that the CLO proteins of the four cotton species were mainly divided into two types: H-caleosins (class I) and L-caleosins (class II). Cis-acting element analysis and quantitative RT–PCR (qRT–PCR) suggested that GhCLOs might be regulated by abscisic acid (ABA) and methyl jasmonate (MeJA). Moreover, transcriptome data and qRT–PCR results revealed that GhCLO genes responded to salt and drought stresses. Under salt stress, gene-silenced plants (TRV: GhCLO06) showed obvious yellowing and wilting, higher malondialdehyde (MDA) content accumulation, and significantly lower activities of superoxide dismutase (SOD) and peroxidase (POD), indicating that GhCLO06 plays a positive regulatory role in cotton salt tolerance. In gene-silenced plants (TRV: GhCLO06), ABA-related genes (GhABF2, GhABI5, and GhNAC4) were significantly upregulated after salt stress, suggesting that the regulation of salt tolerance may be related to the ABA signaling pathway. This research provides an important reference for further understanding and analyzing the molecular regulatory mechanism of CLOs for salt tolerance.

Anticancer and Antimicrobial Activity of Red Sea Seaweeds Extracts-Mediated Gold Nanoparticles

Biosynthesis of gold nanoparticles (AuNPs) is emerging as a better alternative to traditional chemical-based techniques. During this study, extracts of different marine algae species Ulva rigida (green algae), Cystoseira myrica (brown Algae), and Gracilaria foliifera (red Algae) were utilized as reducing and capping agents to synthesize AuNPs. AuNPs capped by U. rigida, C. myrica, and G. foliifera were confirmed by the appearance of surface plasmonic bands at 528, 540, and 543 nm, respectively. Transmission electron microscopy revealed mostly spherical shapes of AuNPs having a size of about 9 nm, 11 nm, and 13 nm for C. myrica, and G. foliifera extracts, respectively. Fourier transform-infrared spectroscopy (FTIR) illustrated the major chemical constituents of U. rigida, C. myrica, and G. foliifera. LC50 values of the biosynthesized AuNPs against Artemia salina nauplii were calculated at a range of concentrations (5-188 μg ml−1) after 16 to 24h. AuNPs concentration-dependent lethality was noted and U. rigida extracts-mediated AuNPs presented the lowest cytotoxicity. The biosynthesized AuNPs exhibited significant anticancer activity (86.83%) against MCF-7 cell lines (human breast adenocarcinoma cell lines) at 188 µg/ml concentration. G. foliifera demonstrated the highest anticancer value (92.13%) followed by C. myrica (89.82%), and U. rigida (86.83%), respectively. The AuNPs synthesized by different algal extracts showed variable antimicrobial activity against the tested pathogenic microorganisms. AuNPs of U. rigida extracts showed significant antimicrobial activity against dermatophytic fungi Trichosporon cataneum (30 mm) followed by Trichophyton mantigrophytes (25 mm). Furthermore, it also exhibited mild activity against Escherichia coli (17 mm), Cryptococcus neoformans (15 mm), Candida albicans (13 mm), and Staphylococcus aureus (11mm), respectively whereas no effects were observed against Bacillus cereus. To conclude, AuNPs can be effectively synthesized by marine algal species, and particularly U. rigida extracts could be effective reducing agents for the green AuNPs synthesis. These AuNPs could potentially serve as efficient alternative anticancer agents against human breast adenocarcinoma and anti-dermatophytes associated with skin infections.

Growth at the limits: comparing trace metal limitation of a freshwater cyanobacterium (Dolichospermum lemmermannii) and a freshwater diatom (Fragilaria crotonensis)

Freshwater phytoplankton blooms are increasing in prevalence and there are conflicting views on whether trace metals limit growth of key species and thus bloom formation. The Taupō Volcanic Zone (TVZ), New Zealand, was formed by multiple eruptions of a super-volcano which emitted rhyolitic tephra leaving lakes depleted in trace metals. This provides an opportunity to test the potential of trace metal limitation on freshwater phytoplankton growth under nanomolar concentrations. Growth responses of two algal species isolated from Lake Taupō, Dolichospermum lemmermannii (cyanobacteria) and Fragilaria crotonensis (diatom), to six biologically important trace metals (manganese, iron, zinc, cobalt, copper and molybdenum) were examined in culture experiments. These were conducted at three trace metal concentrations: (1) ambient, (2) two-times ambient, and (3) ten-times ambient concentrations in Lake Taupō. Elevated concentrations of iron significantly increased growth rates and maximum cell densities in D. lemmermannii, whereas no significant concentration dependence was observed for other trace metals. Fragilaria crotonensis showed no significant growth response to elevated concentrations of trace metals. These results highlight the importance of iron as a growth limiting nutrient for cyanobacteria and indicate that even small (twofold) increases in Fe concentrations could enhance cyanobacteria growth rates in Lake Taupō, potentially causing cyanobacterial blooms.

Diet of European freshwater pearl mussels Margaritifera margaritifera (Mollusca: Bivalvia: Unionoida) in small river (Republic of Karelia, Russia)

The freshwater pearl mussel Margaritifera margaritifera (Linnaeus,1758) is endangered in Europe and is now listed in the Red Data Book of many countries and regions. The diet of the species in the Syskyänjoki River (a tributary of Lake Ladoga) has been studied. The contents of the intestine generally correspond to the composition of seston, and include organic detritus, filamentous and unicellular algae, fragments of invertebrates and macrophyte tissues mixed with silt and sand. The total biomass of the intestinal contents of varied from 0.8 to 30.6 mg per organism (absolutely dry weight). Margaritifera margaritifera consumes a wide range of particles, from 0.5 μm3 (bacteria and unicellular algae) to 200 000 μm3 (fragments of invertebrates and macrophyte tissues). About 90–95% (by volume) of the intestinal contents was consisted by fine organic detritus. The food composition did not differ significantly for mollusks of different sexes and size. In the intestinal contents, 63 taxa of algae were identified. The number of algal species in the content of one intestine varied from 3 to 17, with their abundance from 250 to 9560 cells per organism. The most abundant and constant in the contents of the intestines are unicellular algae. Diatoms are the most diverse, they make up 50.8% of the total number of species.

Biodiversity Patterns and Ecological Preferences of the Photobionts Associated With the Lichen-Forming Genus Parmelia

The worldwide, ecologically relevant lichen-forming genus Parmelia currently includes 41 accepted species, of which the Parmelia sulcata group (PSULgp) and the Parmelia saxatilis group (PSAXgp) have received considerable attention over recent decades; however, phycobiont diversity is poorly known in Parmelia s. lat. Here, we studied the diversity of Trebouxia microalgae associated with 159 thalli collected from 30 locations, including nine Parmelia spp.: P. barrenoae, P. encryptata, P. ernstiae, P. mayi, P. omphalodes, P. saxatilis, P. serrana, P. submontana, and P. sulcata. The mycobionts were studied by carrying out phylogenetic analyses of the nrITS. Microalgae genetic diversity was examined by using both nrITS and LSU rDNA markers. To evaluate putative species boundaries, three DNA species delimitation analyses were performed on Trebouxia and Parmelia. All analyses clustered the mycobionts into two main groups: PSULgp and PSAXgp. Species delimitation identified 13 fungal and 15 algal species-level lineages. To identify patterns in specificity and selectivity, the diversity and abundance of the phycobionts were identified for each Parmelia species. High specificity of each Parmelia group for a given Trebouxia clade was observed; PSULgp associated only with clade I and PSAXgp with clade S. However, the degree of specificity is different within each group, since the PSAXgp mycobionts were less specific and associated with 12 Trebouxia spp., meanwhile those of PSULgp interacted only with three Trebouxia spp. Variation-partitioning analyses were conducted to detect the relative contributions of climate, geography, and symbiotic partner to phycobiont and mycobiont distribution patterns. Both analyses explained unexpectedly high portions of variability (99 and 98%) and revealed strong correlations between the fungal and algal diversity. Network analysis discriminated seven ecological clusters. Even though climatic conditions explained the largest proportion of the variation among these clusters, they seemed to show indifference relative to climatic parameters. However, the cluster formed by P. saxatilis A/P. saxatilis B/Trebouxia sp. 2/Trebouxia sp. S02/Trebouxia sp. 3A was identified to prefer cold-temperate as well as humid summer environments.

Seasonal variation of algal diversity with reference to water quality in Jagadishpur Reservoir, Nepal

The study of the importance of physicochemical parameters of water for algal growth and development in Jagdishpur Reservoir was carried out in the present research. Occurrence of algal species and values of water quality parameters also indicate the ecological nature and the present status of the reservoir. Water samples were collected from Jagdishpur Reservoir in Kapilvastu District (Nepal), in two seasons (wet and dry). The following physicochemical parameters of water were analyzed: temperature, pH, dissolved oxygen, alkalinity, concentration of nitrates and phosphates, free CO2, hardness, conductivity, total dissolved solids. The values of free CO2, hardness, phosphate, temperature, and dissolved oxygen were high in wet season while alkalinity, nitrate, conductivity and total dissolved solid were high in dry season. Altogether 81 algal species belonging to 53 genera and 6 classes were recorded. Higher number of algal species was recorded in the dry season rather than in the wet season. The highest number of species was noted among Chlorophyceae, followed by Cyanobacteria > Bacillariophyceae > Euglenophyceae > Crysophyceae and Dinophyceae. Cosmarium had the highest number of species (13) among all genera. During the wet season, Cosmarium, Calothrix and Phormidium were the genera with the highest number of species while Bulbochaete, Trachelomonas and Gomphonema were genera with the lowest number of species. During the dry season, Cymbella, Cosmarium and Rhopalodia were genera with highest number of species while Euglena, Gloeotrichia and Trachelomonas were genera with lowest number of species. Algal diversity was positively correlated with the increase of alkalinity, conductivity and TDS, while negatively correlated with free CO2, hardness, concerntration of phosphates and nitrates, DO, pH and temperature. Shannon–Weiner diversity index value was higher during the dry season than in the wet season.