Physiological effects of nitrogen deficiency and recovery on the macroalga Gracilariopsis lemaneiformis (Rhodophyta)

Abstract

Algal metabolites are the most promising feedstocks for bio‐energy production. Gracilariopsis lemaneiformis seems to be a good candidate red alga for polysaccharide production, especially relating to the agar production industry. Nitrogen deficiency is an efficient environmental pressure used to increase the accumulation of metabolites in algae. However, there are no studies on the physiological effects of G. lemaneiformis in response to nitrogen deficiency and its subsequent recovery. Here we integrated physiological data with molecular studies to explore the response strategy of G. lemaneiformis under nitrogen deficiency and recovery. Physiological measurements indicated that amino acids and protein biosynthesis were decreased, while endogenous NH4+ and soluble polysaccharides levels were increased under nitrogen stress. The expression of key genes involved in these pathways further suggested that G. lemaneiformis responded to nitrogen stress through up‐regulation or down‐regulation of genes related to nitrogen metabolism, and increased levels of endogenous NH4+ to complement the deficiency of exogenous nitrogen. Consistent with the highest accumulation of soluble polysaccharides, the gene encoding UDP‐glucose pyrophosphorylase, a molecular marker used to evaluate agar content, was dramatically up‐regulated more than 4‐fold compared to the relative expression of actin after 4 d of nitrogen recovery. The present data provide important information on the mechanisms of nutrient balance in macroalgae.

Endoplasmic reticulum-quality control pathway and endoplasmic reticulum-associated degradation mechanism regulate the N-glycoproteins and N-glycan structures in the diatom Phaeodactylum tricornutum

“…The soluble protein was analyzed via Coomassie brilliant blue kit (Jiancheng Biotech Company, Nanjing, China) via UV-VIS spectrophotometry at 595 nm [6]. The soluble sugar was analyzed by the methods of [13] using UV-VIS spectrophotometry at 490 nm. The rapid light curve (RLC) was produced using 10 s pulses of actinic light increased from 0 to 1012 (μmol photons m −2 s −1 ), then the photosynthetic electron transport (ETR) and the maximal photochemical efficiency of PSII (Fv/Fm) was calculated according to pervious study [5].…”

Golgi fucosyltransferase 1 reveals its role in α-1,4-fucose modification of N-glycan in Diatom Phaeodactylum tricornutum

“…The measurement was carried out using UV-VIS spectrophotometry at 620 nm (31). The analysis of soluble protein was performed by BCA protein assay kit (Beyotime Biotechnology, China) using UV-VIS spectrophotometry at 595 nm (32).…”

Impact of Pb on Chlamydomonas reinhardtii at Physiological and Transcriptional Levels

“…Reverse transcription quantitative PCR (qRT-PCR) was performed as previously report (Liu et al, 2019) to determine the transcriptional levels of DEGs. All qPCR reactions were performed using Quant qRT-PCR kit [Tiangen Biotech(Beijing) Co., Ltd., Beijing, China].…”