scholarly journals Morphological Features and Cold-Response Gene Expression in Mesophilic Bacillus cereus Group and Psychrotolerant Bacillus cereus Group under Low Temperature

2021 ◽  
Vol 9 (6) ◽  
pp. 1255
Author(s):  
Kyung-Min Park ◽  
Hyun-Jung Kim ◽  
Min-Sun Kim ◽  
Minseon Koo
Keyword(s):  
Gene Expression ◽  
Fatty Acid ◽  
Low Temperature ◽  
Bacillus Cereus ◽  
Low Temperatures ◽  
Fatty Acid Biosynthesis ◽  
Morphological Changes ◽  
Growth Strategies ◽  
Acid Biosynthesis ◽  
Bacillus Cereus Group

At low temperatures, psychrotolerant B. cereus group strains exhibit a higher growth rate than mesophilic strains do. However, the different survival responses of the psychrotolerant strain (BCG34) and the mesophilic strain (BCGT) at low temperatures are unclear. We investigated the morphological and genomic features of BCGT and BCG34 to characterize their growth strategies at low temperatures. At low temperatures, morphological changes were observed only in BCGT. These morphological changes included the elongation of rod-shaped cells, whereas the cell shape in BCG34 was unchanged at the low temperature. A transcriptomic analysis revealed that both species exhibited different growth-related traits during low-temperature growth. The BCGT strain induces fatty acid biosynthesis, sulfur assimilation, and methionine and cysteine biosynthesis as a survival mechanism in cold systems. Increases in energy metabolism and fatty acid biosynthesis in the mesophilic B. cereus group strain might explain its ability to grow at low temperatures. Several pathways involved in carbohydrate mechanisms were downregulated to conserve the energy required for growth. Peptidoglycan biosynthesis was upregulated, implying that a change of gene expression in both RNA-Seq and RT-qPCR contributed to sustaining its growth and rod shape at low temperatures. These results improve our understanding of the growth response of the B. cereus group, including psychrotolerant B. cereus group strains, at low temperatures and provide information for improving bacterial inhibition strategies in the food industry.

scholarly journals Low-temperature effects on docosahexaenoic acid biosynthesis in Schizochytrium sp. TIO01 and its proposed underlying mechanism

2020 ◽  
Vol 13 (1) ◽  
Author(s):  
Fan Hu ◽  
April L. Clevenger ◽  
Peng Zheng ◽  
Qiongye Huang ◽  
Zhaokai Wang
Keyword(s):  
Fatty Acid ◽  
Low Temperature ◽  
Fatty Acid Synthesis ◽  
Low Temperatures ◽  
Temperature Effects ◽  
Fatty Acid Biosynthesis ◽  
Underlying Mechanism ◽  
Acid Synthesis ◽  
Acid Biosynthesis ◽  
Fas Pathway

Abstract Background Schizochytrium species are known for their abundant production of docosahexaenoic acid (DHA). Low temperatures can promote the biosynthesis of polyunsaturated fatty acids (PUFAs) in many species. This study investigates low-temperature effects on DHA biosynthesis in Schizochytrium sp. TIO01 and its underlying mechanism. Results The Schizochytrium fatty acid biosynthesis pathway was evaluated based on de novo genome assembly (contig N50 = 2.86 Mb) and iTRAQ-based protein identification. Our findings revealed that desaturases, involved in DHA synthesis via the fatty acid synthase (FAS) pathway, were completely absent. The polyketide synthase (PKS) pathway and the FAS pathway are, respectively, responsible for DHA and saturated fatty acid synthesis in Schizochytrium. Analysis of fatty acid composition profiles indicates that low temperature has a significant impact on the production of DHA in Schizochytrium, increasing the DHA content from 43 to 65% of total fatty acids. However, the expression levels of PKS pathway genes were not significantly regulated as the DHA content increased. Further, gene expression analysis showed that pathways related to the production of substrates (acetyl-CoA and NADPH) for fatty acid synthesis (the branched-chain amino acid degradation pathway and the pentose phosphate pathway) and genes related to saturated fatty acid biosynthesis (the FAS pathway genes and malic enzyme) were, respectively, upregulated and downregulated. These results indicate that low temperatures increase the DHA content by likely promoting the entry of relatively large amounts of substrates into the PKS pathway. Conclusions In this study, we provide genomic, proteomic, and transcriptomic evidence for the fatty acid synthesis pathway in Schizochytrium and propose a mechanism by which low temperatures promote the accumulation of DHA in Schizochytrium. The high-quality and nearly complete genome sequence of Schizochytrium provides a valuable reference for investigating the regulation of polyunsaturated fatty acid biosynthesis and the evolutionary characteristics of Thraustochytriidae species.

scholarly journals Amino Acids Attenuate Insulin Action on Gluconeogenesis and Promote Fatty Acid Biosynthesis via mTORC1 Signaling Pathway in trout Hepatocytes

2015 ◽  
Vol 36 (3) ◽  
pp. 1084-1100 ◽  
Author(s):  
Weiwei Dai ◽  
Stéphane Panserat ◽  
Elisabeth Plagnes-Juan ◽  
Iban Seiliez ◽  
Sandrine Skiba-Cassy
Keyword(s):  
Gene Expression ◽  
Amino Acids ◽  
Fatty Acid ◽  
P38 Mapk ◽  
Insulin Action ◽  
Fatty Acid Biosynthesis ◽  
Acute Administration ◽  
Dependent Manner ◽  
Acid Biosynthesis ◽  
Mtorc1 Signaling

Background/Aims: Carnivores exhibit poor utilization of dietary carbohydrates and glucose intolerant phenotypes, yet it remains unclear what are the causal factors and underlying mechanisms. We aimed to evaluate excessive amino acids (AAs)-induced effects on insulin signaling, fatty acid biosynthesis and glucose metabolism in rainbow trout and determine the potential involvement of mTORC1 and p38 MAPK pathway. Methods: We stimulated trout primary hepatocytes with different AA levels and employed acute administration of rapamycin to inhibit mTORC1 activation. Results: Increased AA levels enhanced the phosphorylation of ribosomal protein S6 kinase (S6K1), S6, and insulin receptor substrate 1 (IRS-1) on Ser302 but suppressed Akt and p38 phosphorylation; up-regulated the expression of genes related to gluconeogenesis and fatty acid biosynthesis. mTORC1 inhibition not only inhibited the phosphorylation of mTORC1 downstream targets, but also blunted IRS-1 Ser302 phosphorylation and restored excessive AAs-suppressed Akt phosphorylation. Rapamycin also inhibited fatty acid biosynthetic and gluconeogenic gene expression. Conclusion: High levels of AAs up-regulate hepatic fatty acid biosynthetic gene expression through an mTORC1-dependent manner, while attenuate insulin-mediated repression of gluconeogenesis through elevating IRS-1 Ser302 phosphorylation, which in turn impairs Akt activation and thereby weakening insulin action. We propose that p38 MAPK probably also involves in these AAs-induced metabolic changes.

scholarly journals The effects of low temperature on docosahexaenoic acid biosynthesis in Schizochytrium sp TIO01 and the underlying mechanism

2020 ◽  
Author(s):  
Fan Hu ◽  
April L. Clevenger ◽  
Peng Zheng ◽  
Qiongye Huang ◽  
Zhaokai Wang
Keyword(s):  
Fatty Acids ◽  
Fatty Acid ◽  
Low Temperature ◽  
Saturated Fatty Acid ◽  
Fatty Acid Synthesis ◽  
Low Temperatures ◽  
Underlying Mechanism ◽  
Acid Synthesis ◽  
Acid Biosynthesis ◽  
Fas Pathway

Abstract Background Schizochytrium are known for their abundant production of docosahexaenoic acid (DHA). Low temperatures can promote the biosynthesis of polyunsaturated fatty acids in many species. In this study, the effects of low temperature on the biosynthesis of DHA in Schizochytrium sp TIO01 and the underlying mechanism was investigated. Results Based on the de novo genome assembly (contig N50=2.86 Mb) and iTRAQ-based protein identification, we first reconstructed the detailed Schizochytrium fatty acid biosynthesis pathway. Our findings revealed that desaturases, involved in DHA synthesis via the fatty acid synthase (FAS) pathway, were completely absent. The polyketide synthase (PKS) pathway and the FAS pathway are separately responsible for DHA and saturated fatty acid synthesis in Schizochytrium . Analysis of fatty acid composition profiles indicates that low temperature has a significant impact on the production of DHA in Schizochytrium, increasing the DHA content and overall total fatty acids from 43% to 65%. The increased DHA content, however, was not a result of the expression of the PKS pathway genes. Further gene expression analysis indicated that low temperatures may promote DHA accumulation by the up-regulation of both the pentose phosphate pathway and the branched-chain amino acid degradation pathway (increasing the production of the substrates for polyunsaturated fatty acid synthesis: acetyl-CoA and NADPH). In addition, low temerpatures result in a down-regulation of the FAS pathway (reducing the consumption of the substrates for saturated fatty acid synthesis) and malic enzyme, leading to a decreased saturated fatty acid content. Conclusions These findings elucidate the detailed fatty acid synthesis pathway of Schizochytrium, revealing an underlying mechanism by which low temperatures promote the accumulation of DHA in Schizochytrium. The high-quality and nearly complete genome sequence of Schizochytrium provides a valuable reference for further investigation of the regulation of polyunsaturated fatty acids biosynthesisand the evolutionary characteristics in Thraustochytriidae species.

Chronic intermittent hypoxia upregulates genes of lipid biosynthesis in obese mice

2005 ◽  
Vol 99 (5) ◽  
pp. 1643-1648 ◽  
Author(s):  
Jianguo Li ◽  
Dmitry N. Grigoryev ◽  
Shui Qing Ye ◽  
Laura Thorne ◽  
Alan R. Schwartz ◽  
...  
Keyword(s):  
Gene Expression ◽  
Fatty Acid ◽  
Fatty Liver ◽  
Real Time ◽  
Real Time Pcr ◽  
Intermittent Hypoxia ◽  
Fatty Acid Biosynthesis ◽  
Lipid Biosynthesis ◽  
Chronic Intermittent Hypoxia ◽  
Acid Biosynthesis

Obstructive sleep apnea (OSA), a condition tightly linked to obesity, leads to chronic intermittent hypoxia (CIH) during sleep. There is emerging evidence that OSA is independently associated with insulin resistance and fatty liver disease, suggesting that OSA may affect hepatic lipid metabolism. To test this hypothesis, leptin-deficient obese ( ob/ob) mice were exposed to CIH during the light phase (9 AM–9 PM) for 12 wk. Liver lipid content and gene expression profile in the liver (Affymetrix 430 GeneChip with real-time PCR validation) were determined on completion of the exposure. CIH caused a 30% increase in triglyceride and phospholipid liver content ( P < 0.05), whereas liver cholesterol content was unchanged. Gene expression analysis showed that CIH upregulated multiple genes controlling 1) cholesterol and fatty acid biosynthesis [malic enzyme and acetyl coenzyme A (CoA) synthetase], 2) predominantly fatty acid biosynthesis (acetyl-CoA carboxylase and stearoyl-CoA desaturases 1 and 2), and 3) triglyceride and phospholipid biosynthesis (mitochondrial glycerol-3-phosphate acyltransferase). A majority of overexpressed genes were transcriptionally regulated by sterol regulatory element-binding protein (SREBP) 1, a master regulator of lipogenesis. A 2.8-fold increase in SREBP-1 gene expression in CIH was confirmed by real-time PCR ( P = 0.001). Expression of major genes of cholesterol biosynthesis, SREBP-2 and 3-hydroxy-3-methylglutaryl-CoA reductase, was unchanged. In conclusion, we have shown that CIH may exacerbate preexisting fatty liver of obesity via upregulation of the pathways of lipid biosynthesis in the liver.

scholarly journals Cold Shock Response of Bacillus subtilis: Isoleucine-Dependent Switch in the Fatty Acid Branching Pattern for Membrane Adaptation to Low Temperatures

1999 ◽  
Vol 181 (17) ◽  
pp. 5341-5349 ◽  
Author(s):  
Wolfgang Klein ◽  
Michael H. W. Weber ◽  
Mohamed A. Marahiel
Keyword(s):  
Fatty Acids ◽  
Fatty Acid ◽  
Fatty Acid Profile ◽  
Low Temperatures ◽  
Cold Shock ◽  
Fatty Acid Biosynthesis ◽  
Branching Pattern ◽  
Acid Biosynthesis ◽  
Branched Fatty Acids ◽  
Cold Sensitive

ABSTRACT Bacillus subtilis has developed sophisticated mechanisms to withstand fluctuations in temperature. Membrane fatty acids are the major determinants for a sufficiently fluid membrane state to ensure the membrane’s function at all temperatures. The fatty acid profile of B. subtilis is characterized by a high content of branched fatty acids irrespective of the growth medium. Here, we report on the importance of isoleucine for B. subtilis to survive cold shock from 37 to 15°C. Cold shock experiments with strain JH642 revealed a cold-protective function for all intermediates of anteiso-branched fatty acid biosynthesis. Metabolites related to iso-branched or straight-chain fatty acid biosynthesis were not protective. Fatty acid profiles of differentB. subtilis wild-type strains proved the altered branching pattern by an increase in the anteiso-branched fatty acid content and a concomitant decrease of iso-branched species during cold shock. There were no significant changes in the fatty acid saturation or acyl chain length. The cold-sensitive phenotype of isoleucine-deficient strains in the absence of isoleucine correlated with their inability to synthesize more anteiso-branched fatty acids, as shown by the fatty acid profile. The switch to a fatty acid profile dominated by anteiso-C15:0 and C17:0 at low temperatures and the cold-sensitive phenotype of isoleucine-deficient strains in the absence of isoleucine focused our attention on the critical role of anteiso-branched fatty acids in the growth of B. subtilisin the cold.

Inhibition of early steps of de novo fatty-acid biosynthesis by different xenobiotica

1991 ◽  
Vol 81 (2) ◽  
pp. 251-255
Author(s):  
Manfred Focke ◽  
Andrea Feld ◽  
Hartmut K. Lichtenthaler
Keyword(s):  
Fatty Acid ◽  
Fatty Acid Biosynthesis ◽  
De Novo ◽  
Acid Biosynthesis
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