Identification of a RelA/SpoT Homolog and Its Possible Role in the Accumulation of Astaxanthin in .

A RelA/SpoT homolog, HpRSH, was identified in . HpRSH was found to catalyze Mg-dependent guanosine tetraphosphate (ppGpp) synthesis and Mn-dependent ppGpp hydrolysis, respectively. The transcription of HpRSH was significantly upregulated by environmental stresses, such as darkness, high light, nitrogen limitation, and salinity stress.

Stringent Response Regulates Stress Resistance in Cyanobacterium .

Cyanobacterial blooms are serious environmental issues in global freshwater ecosystems. Nitrogen limitation is one of the most important strategies to control cyanobacterial blooms. However, recent researches showed that N limitation does not effectively control the bloom; oppositely, N limitation induces N-fixing cyanobacterial blooms.

Optimization of extraction solvents, solid phase extraction and decoupling for quantitation of free isoprenoid diphosphates in Haematococcus pluvialis by liquid chromatography with tandem mass spectrometry.

Isoprenoid diphosphates are important precursors actively participating in many downstream metabolisms; they are often in modified forms, e.g., protein-coupled or esterified form.

A rapid UHPLC-HILIC method for algal guanosine 5'-diphosphate 3'-diphosphate (ppGpp) and the potential separation mechanism.

A fast and facile hydrophilic interaction liquid chromatography (HILIC) method was developed and applied to quantify physiologically important ppGpp and its analogues in a tough sample, the astaxanthin-accumulating alga Hameatococcus pluvialis. The method is able to analyze simultaneously seven nucleotides, including ppGpp at the order of pmol g cells within 12 min. Mechanism on the elution order was investigated.

A Novel Hydrolytic Activity of Tri-Functional Geranylgeranyl Pyrophosphate Synthase in Haematococcus pluvialis.

Under environmental stresses, Haematococcus pluvialis accumulates large amounts of carotenoids. Scale of carotenoid biosynthesis depends on availability of geranylgeranyl pyrophosphate (GGPP) precursor, which is supplied by GGPP synthase (GGPPS) through sequential 1'-4 condensation of three isopentenyl pyrophosphates (IPPs) into dimethylallyl pyrophosphate (DMAPP). Using IPP and DMAPP as substrates, a tri-functional HpGGPPS was identified in this study to promiscuously synthesize allylic prenyl pyrophosphates (PPPs), e.

Functional Characterization of a Missing Branch Component in for Control of Algal Carotenoid Biosynthesis.

Cyclization of acyclic lycopene by cyclases marks an important regulatory point in carotenoid biosynthesis. Though some algal lycopene epsilon cyclases (LCYEs) have been predicted computationally, very few have been functionally identified. Little is known about the regulation mechanisms of algal LCYEs.

Simultaneous determination of 13 carotenoids by a simple C18 column-based ultra-high-pressure liquid chromatography method for carotenoid profiling in the astaxanthin-accumulating Haematococcus pluvialis.

A simple ultra-high-pressure liquid chromatography (UHPLC) method for rapidly and simultaneously identifying thirteen carotenoids in Haematococcus pluvialis was developed in this study. The method is capable of effectively separating two astaxanthin isomers, two ζ-carotene isomers, and three phytoene isomers on two simple C18 columns within 9 and 12min only by using methanol and acetonitrile, respectively. To our best knowledge, this is the rapidest method for these carotenoid isomers, currently.

Diverse Profiles of AI-1 Type Quorum Sensing Molecules in Cultivable Bacteria from the Mangrove () Rhizosphere Environment.

Mangrove rhizosphere environment harbors diverse populations of microbes, and some evidence showed that rhizobacteria behavior was regulated by quorum sensing (QS). Investigating the diverse profiles of QS molecules in mangrove ecosystems may shed light on the bacterial roles and lead to a better understanding of the symbiotic interactions between plants and microbes. The aims of the current study focus on identifying AI-1 type QS signals, i.

[Roles of microbes in matter cycles in phycosphere niche.].

Phytoplankton is the main driver of marine primary production and matter cycles. Their ecological functions have closely linked to the associated microbes. Although microbial biodiversity is high in all kinds of algal hosts (such as dinoflagellate, diatoms and blue-green algae), some he-terotrophic bacteria (Alphaproteobacteria, Gammaproteobacteria, Flavobacteria, and Actinobacteria) often appear as the dominant communities.