Phage Infection Benefits Marine Diatom Phaeodactylum tricornutum by Regulating the Associated Bacterial Community.

The interaction between marine phyto- and bacterioplankton is regulated by multiple environmental and biological factors. Among them, phages as the major regulators of bacterial mortality are considered to have important impacts on algae-associated bacteria and algae-bacteria relationship. However, little is currently known about the actual impact of phages from this perspective.

A dark-tolerant diatom (Chaetoceros) cultured from the deep sea.

Although the extreme conditions of the deep sea are typically not suitable for the growth of photosynthetic algae, accumulating evidence indicates that there are diverse healthy phytoplankton living in this environment. However, living phytoplankton from the deep sea have rarely been isolated and cultivated, and so our understanding of where they come from and how they adapt to (or tolerate) the extreme deep-sea environment is limited. Here, under long-term dark stress and subsequent light treatment, we successfully isolated a diatom from a depth of 1,000 m in the Western Pacific Ocean.

A Novel Phage Indirectly Regulates Diatom Growth by Infecting a Diatom-Associated Biofilm-Forming Bacterium.

Algae and heterotrophic bacteria have close and intricate interactions, which are regulated by multiple factors in the natural environment. Phages are the major factor determining bacterial mortality rates. However, their impacts on the alga-associated bacteria and thus on the alga-bacterium interactions are poorly understood.

Insight Into the Pico- and Nano-Phytoplankton Communities in the Deepest Biosphere, the Mariana Trench.

As photoautotrophs, phytoplankton are generally present in the euphotic zone of the ocean, however, recently healthy phytoplankton cells were found to be also ubiquitous in the dark deep sea, i.e., at water depths between 2000 and 4000 m.

Cyclobutane pyrimidine dimers photolyase from extremophilic microalga: remarkable UVB resistance and efficient DNA damage repair.

Bacteria living in the Antarctic region have developed several adaptive features for growth and survival under extreme conditions. Chlamydomonas sp. ICE-Lis well adapted to high levels of solar UV radiation.

Effects of CO2 and seawater acidification on the early stages of Saccharina japonica development.

In this paper, we demonstrated that ocean acidification (OA) had significant negative effects on the microscopic development of Saccharina japonica in a short-term exposure experiment under a range of light conditions. Under elevated CO2, the alga showed a significant reduction in meiospore germination, fecundity, and reproductive success. Larger female and male gametophytes were noted to occur under high CO2 conditions and high light magnified these positive effects.

Long-term experiment on physiological responses to synergetic effects of ocean acidification and photoperiod in the Antarctic sea ice algae Chlamydomonas sp. ICE-L.

Studies on ocean acidification have mostly been based on short-term experiments of low latitude with few investigations of the long-term influence on sea ice communities. Here, the combined effects of ocean acidification and photoperiod on the physiological response of the Antarctic sea ice microalgae Chlamydomonas sp. ICE-L were examined.

Expression of fatty acid desaturase genes and fatty acid accumulation in Chlamydomonas sp. ICE-L under salt stress.

The Antarctic ice microalgae Chlamydomonas sp. ICE-L which is highly resistant to salt stress holds promise in providing an alternative species for the production of microalgal oil. We studied the effects of the alga in confrontation with NaCl stress on the growth, oil yield and expression of fatty acid desaturase genes.

Occurrence of the PsbS and LhcSR products in the green alga Ulva linza and their correlation with excitation pressure.

To avoid photoinhibition, plants have developed diverse photoprotection mechanisms. One of the short-term high light protection mechanisms in plants is non-photochemical quenching (NPQ), which dissipates the absorbed light energy as thermal energy. In the green alga, Ulva linza, the kinetics of NPQ starts with an initial, quick rise followed by a decline, and then a second and higher rise at longer time periods.

Activities of principal photosynthetic enzymes in green macroalga Ulva linza: functional implication of C₄ pathway in CO₂ assimilation.

The green-tide-forming macroalga Ulva linza was profiled by transcriptome sequencing to ascertain whether the alga carries both C3 and C4 photosynthesis genes. The key enzymes involved in C4 metabolism including pyruvate orthophosphate dikinase (PPDK), phosphoenolpyruvate carboxylase (PEPC), and phosphoenolpyruvate carboxykinase (PCK) were found. When measured under normal and different stress conditions, expression of rbcL was higher under normal conditions and lower under the adverse conditions, whereas that of PPDK was higher under some adverse conditions, namely desiccation, high salinity, and low salinity.

Temperature regulates fatty acid desaturases at a transcriptional level and modulates the fatty acid profile in the Antarctic microalga Chlamydomonas sp. ICE-L.

Chlamydomonas sp. ICE-L which can thrive in extreme environments of the Antarctic is a major biomass producer. The FAD genes in Chlamydomonas sp.

Analysis of ΔpH and the xanthophyll cycle in NPQ of the Antarctic sea ice alga Chlamydomonas sp. ICE-L.

Non-photochemical fluorescence quenching (NPQ) is mainly associated with the transthylakoid proton gradient (ΔpH) and xanthophyll cycle. However, the exact mechanism of NPQ is different in different oxygenic photosynthetic organisms. In this study, several inhibitors were used to study NPQ kinetics in the sea ice alga Chlamydomonas sp.

A transthylakoid proton gradient and inhibitors induce a non-photochemical fluorescence quenching in unicellular algae Nannochloropsis sp.

Non-photochemical quenching (NPQ) of chlorophyll fluorescence is thought to be an indicator of an essential regulation and photoprotection mechanism against high-light stress in photosynthetic organisms. In this report, special chemicals were used to perturb the kinetics of the ΔpH build-up and the xanthophyll cycle (XC) in Nannochloropsis sp. We found that NPQ was stimulated rapidly on exposure to high light and relaxed rapidly in darkness.

Complete mitochondrial genome of the sea slug, Placida sp., contains unusual noncoding regions.

The complete sequence (14,751 bp) of the mitochondrial DNA (mtDNA) of the opisthobranch gastropod Placida sp. was determined using long PCR and genome-walking techniques. The genome contains 13 protein-coding genes (PCG), 2 ribosomal RNA (rRNA), 22 transfer RNA (tRNA) genes that are typical of metazoan mtDNA, and 2 lengthy noncoding regions with a total length of 1441 bp.

Detection and quantitation of lipid in the microalga Tetraselmis subcordiformis (Wille) Butcher with BODIPY 505/515 staining.

BODIPY 505/515, a lipophilic bright green fluorescent dye was tested for lipid detection in the microalga Tetraselmis subcordiformis. A concentration of 0.28 μg ml(-1) and staining for 6 min was optimal.

De novo sequencing and analysis of the Ulva linza transcriptome to discover putative mechanisms associated with its successful colonization of coastal ecosystems.

Background: The green algal genus Ulva Linnaeus (Ulvaceae, Ulvales, Chlorophyta) is well known for its wide distribution in marine, freshwater, and brackish environments throughout the world. The Ulva species are also highly tolerant of variations in salinity, temperature, and irradiance and are the main cause of green tides, which can have deleterious ecological effects. However, limited genomic information is currently available in this non-model and ecologically important species.

Evaluation of putative internal reference genes for gene expression normalization in Nannochloropsis sp. by quantitative real-time RT-PCR.

Quantitative real-time reverse transcription PCR (RT-qPCR), a sensitive technique for quantifying gene expression, depends on the stability of the reference gene(s) used for data normalization. To date, few studies on reference genes have been undertaken for Nannochloropsis sp. In this study, 12 potential reference genes were evaluated for their expression stability using the geNorm and NormFinder statistical algorithms by RT-qPCR.

Evidence of coexistence of C₃ and C₄ photosynthetic pathways in a green-tide-forming alga, Ulva prolifera.

Ulva prolifera, a typical green-tide-forming alga, can accumulate a large biomass in a relatively short time period, suggesting that photosynthesis in this organism, particularly its carbon fixation pathway, must be very efficient. Green algae are known to generally perform C₃ photosynthesis, but recent metabolic labeling and genome sequencing data suggest that they may also perform C₄ photosynthesis, so C₄ photosynthesis might be more wide-spread than previously anticipated. Both C₃ and C₄ photosynthesis genes were found in U.

Cloning and expression analysis of two different LhcSR genes involved in stress adaptation in an Antarctic microalga, Chlamydomonas sp. ICE-L.

Light-harvesting complexes (LHCs) play essential roles in light capture and photoprotection. Although the functional diversity of individual LHCs in many plants has been well described, knowledge regarding the extent of this family in the majority of green algal groups is still limited. In this study, two different LhcSR genes, LhcSR1 and LhcSR2 from Chlamydomonas sp.

The validity of a reference gene is highly dependent on the experimental conditions in green alga Ulva linza.

Normalization based on inappropriate reference gene may lead to the reduction of the accuracy of RT-qPCR. Although determination of suitable reference genes is essential to RT-qPCR studies, reports on the evaluation of reference genes in Ulva linza, a ubiquitous green-tide forming alga, are lacking. The expression levels of ten candidate reference genes were analyzed in U.