Phytate as a phosphorus nutrient with impacts on iron stress-related gene expression for phytoplankton: insights from diatom Phaeodactylum tricornutum

Phytoplankton have evolved a capability to acquire phosphorus (P) from dissolved organic phosphorus (DOP) since the preferred form, dissolved inorganic phosphate (DIP, or Pi), is often limited in parts of the ocean. Phytic acid (PA) is abundantly synthesized in plants and rich in excreta of animals, potentially enriching the DOP pool in coastal oceans. However, whether and how PA may be used by phytoplankton are poorly understood. Here, we investigated PA utilization and underlying metabolic pathways in the diatom model Phaeodactylum tricornutum . The physiological results showed that P. tricornutum could utilize PA as a sole source of P nutrient to support growth. Meanwhile, the replacement of PA for DIP also caused changes in multiple cellular processes such as inositol phosphate metabolism, photosynthesis, and signal transduction. These results suggest that PA is bioavailable to P. tricornutum and can directly participate the metabolic pathways of PA-grown cells. However, our data showed that the utilization of PA was markedly less efficient than that of DIP, and PA-grown cells exhibited P and iron (Fe) nutrient stress signals. Implicated in these findings is the potential of complicated responses of phytoplankton to an ambient DOP species, which calls for more systematic investigation. IMPORTANCE PA is abundant in plants, and cannot be digested by non-ruminant animals. Hence, it is potentially a significant component of the DOP pool in the coastal waters. Despite the potential importance, there is little information about its bioavailability to phytoplankton as a source of P nutrient and if so what molecular mechanisms are involved. In this study, we found that part of PA could be utilized by the diatom P. tricornutum to support growth, and another portion of PA can act as a substrate directly participating in various metabolism pathways and cellular processes. However, our physiological and transcriptomic data show that PA-grown cells still exhibited signs of P stress and potential Fe stress. These results have significant implications in phytoplankton P nutrient ecology and provide a novel insight into multi-faceted impacts of DOP utilization on phytoplankton nutrition and metabolism.

Untargeted GC-MS-Based Metabolomics for Early Detection of Colorectal Cancer

BackgroundColorectal cancer (CRC) is one of the most common malignant gastrointestinal cancers in the world with a 5-year survival rate of approximately 68%. Although researchers accumulated many scientific studies, its pathogenesis remains unclear yet. Detecting and removing these malignant polyps promptly is the most effective method in CRC prevention. Therefore, the analysis and disposal of malignant polyps is conducive to preventing CRC.MethodsIn the study, metabolic profiling as well as diagnostic biomarkers for CRC was investigated using untargeted GC-MS-based metabolomics methods to explore the intervention approaches. In order to better characterize the variations of tissue and serum metabolic profiles, orthogonal partial least-square discriminant analysis was carried out to further identify significant features. The key differences in tR–m/z pairs were screened by the S-plot and VIP value from OPLS-DA. Identified potential biomarkers were leading in the KEGG in finding interactions, which show the relationships among these signal pathways.ResultsFinally, 17 tissue and 13 serum candidate ions were selected based on their corresponding retention time, p-value, m/z, and VIP value. Simultaneously, the most influential pathways contributing to CRC were inositol phosphate metabolism, primary bile acid biosynthesis, phosphatidylinositol signaling system, and linoleic acid metabolism.ConclusionsThe preliminary results suggest that the GC-MS-based method coupled with the pattern recognition method and understanding these cancer-specific alterations could make it possible to detect CRC early and aid in the development of additional treatments for the disease, leading to improvements in CRC patients’ quality of life.

A Mediation Approach to Discovering Causal Relationships between the Metabolome and DNA Methylation in Type 1 Diabetes

Environmental factors including viruses, diet, and the metabolome have been linked with the appearance of islet autoimmunity (IA) that precedes development of type 1 diabetes (T1D). We measured global DNA methylation (DNAm) and untargeted metabolomics prior to IA and at the time of seroconversion to IA in 92 IA cases and 91 controls from the Diabetes Autoimmunity Study in the Young (DAISY). Causal mediation models were used to identify seven DNAm probe-metabolite pairs in which the metabolite measured at IA mediated the protective effect of the DNAm probe measured prior to IA against IA risk. These pairs included five DNAm probes mediated by histidine (a metabolite known to affect T1D risk), one probe (cg01604946) mediated by phostidyl choline p-32:0 or o-32:1, and one probe (cg00390143) mediated by sphingomyelin d34:2. The top 100 DNAm probes were over-represented in six reactome pathways at the FDR <0.1 level (q = 0.071), including transport of small molecules and inositol phosphate metabolism. While the causal pathways in our mediation models require further investigation to better understand the biological mechanisms, we identified seven methylation sites that may improve our understanding of epigenetic protection against T1D as mediated by the metabolome.

Full-length transcriptome profiling reveals insight into the cold response of two kiwifruit genotypes (A. arguta) with contrasting freezing tolerances

Background Kiwifruit (Actinidia Lindl.) is considered an important fruit species worldwide. Due to its temperate origin, this species is highly vulnerable to freezing injury while under low-temperature stress. To obtain further knowledge of the mechanism underlying freezing tolerance, we carried out a hybrid transcriptome analysis of two A. arguta (Actinidi arguta) genotypes, KL and RB, whose freezing tolerance is high and low, respectively. Both genotypes were subjected to − 25 °C for 0 h, 1 h, and 4 h. Results SMRT (single-molecule real-time) RNA-seq data were assembled using the de novo method, producing 24,306 unigenes with an N50 value of 1834 bp. Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analysis of DEGs showed that they were involved in the ‘starch and sucrose metabolism’, the ‘mitogen-activated protein kinase (MAPK) signaling pathway’, the ‘phosphatidylinositol signaling system’, the ‘inositol phosphate metabolism’, and the ‘plant hormone signal transduction’. In particular, for ‘starch and sucrose metabolism’, we identified 3 key genes involved in cellulose degradation, trehalose synthesis, and starch degradation processes. Moreover, the activities of beta-GC (beta-glucosidase), TPS (trehalose-6-phosphate synthase), and BAM (beta-amylase), encoded by the abovementioned 3 key genes, were enhanced by cold stress. Three transcription factors (TFs) belonging to the AP2/ERF, bHLH (basic helix-loop-helix), and MYB families were involved in the low-temperature response. Furthermore, weighted gene coexpression network analysis (WGCNA) indicated that beta-GC, TPS5, and BAM3.1 were the key genes involved in the cold response and were highly coexpressed together with the CBF3, MYC2, and MYB44 genes. Conclusions Cold stress led various changes in kiwifruit, the ‘phosphatidylinositol signaling system’, ‘inositol phosphate metabolism’, ‘MAPK signaling pathway’, ‘plant hormone signal transduction’, and ‘starch and sucrose metabolism’ processes were significantly affected by low temperature. Moreover, starch and sucrose metabolism may be the key pathway for tolerant kiwifruit to resist low temperature damages. These results increase our understanding of the complex mechanisms involved in the freezing tolerance of kiwifruit under cold stress and reveal a series of candidate genes for use in breeding new cultivars with enhanced freezing tolerance.

Comprehensive Evaluation and Analysis of the Salinity Stress Response Mechanisms Based on Transcriptome and Metabolome of Staphylococcus Aureus

Staphylococcus aureus possesses an extraordinary ability to deal with a wide range of osmotic pressure. To performed transcriptomic and metabolomic analyses on the potential mechanism of gradient salinity stress adaptation in S. aureus ZS01. The results revealed that CPS biosynthetic protein genes were candidate target genes for directly regulating the phenotypic changes of biofilm. Inositol phosphate metabolism was downregulated to reduce the conversion of functional molecules. Gluconeogenesis pathway was downregulated to reduce the production of endogenous glucose. Pyruvate metabolism pathway was upregulated to promote the accumulation of succinate. TCA cycle metabolism pathway was downregulated to reduce unnecessary energy loss. These self-protection mechanisms can protect cells from hypertonic environments, and help them focus on survival. In addition, we identified 10 hub genes. The findings will aid in the prevention and treatment strategies of S. aureus infections.

Dietary phosphorus and calcium in feed affects miRNA profiles and their mRNA targets in jejunum of two strains of laying hens

Phosphorus (P) and calcium (Ca) are critical for egg production in laying hens. Most of P in plant-based poultry diet is bound as phytic acid and needs to be hydrolysed before absorption. To increase P bioavailability, exogenous phytases or bioavailable rock phosphate is added in feed. There is growing evidence of the importance of miRNAs as the epicentre of intestinal homeostasis and functional properties. Therefore, we demonstrated the expression of miRNA profiles and the corresponding target genes due to the different levels of P (recommended vs. 20% reduction) and/or Ca (recommended vs. 15% reduction) in feed. Jejunal miRNA profiles of Lohmann Selected Leghorn (LSL) and Lohmann Brown (LB) laying hens strains were used (n = 80). A total of 34 and 76 miRNAs were differentially expressed (DE) in the different diet groups within LSL and LB strains respectively. In LSL, the DE miRNAs and their targets were involved in calcium signaling pathway, inositol phosphate metabolism, and mitochondrial dysfunction. Similarly, in LB miRNAs targets were enriched in metabolic pathways such as glutathione metabolism, phosphonate metabolism and vitamin B6 metabolism. Our results suggest that both strains employ different intrinsic strategies to cope with modulated P and Ca supply and maintain mineral homeostasis.

Inositol Signaling in the Basidiomycete Fungus Schizophyllum commune

Intracellular signaling is conserved in eukaryotes to allow for response to extracellular signals and to regulate development and cellular functions. In fungi, inositol phosphate signaling has been shown to be involved in growth, sexual reproduction, and metabolic adaptation. However, reports on mushroom-forming fungi are lacking so far. In Schizophyllum commune, an inositol monophosphatase has been found up-regulated during sexual development. The enzyme is crucial for inositol cycling, where it catalyzes the last step of inositol phosphate metabolism, restoring the inositol pool from the monophosphorylated inositol monophosphate. We overexpressed the gene in this model basidiomycete and verified its involvement in cell wall integrity and intracellular trafficking. Strong phenotypes in mushroom formation and cell metabolism were evidenced by proteome analyses. In addition, altered inositol signaling was shown to be involved in tolerance towards cesium and zinc, and increased metal tolerance towards cadmium, associated with induced expression of kinases and repression of phosphatases within the inositol cycle. The presence of the heavy metals Sr, Cs, Cd, and Zn lowered intracellular calcium levels. We could develop a model integrating inositol signaling in the known signal transduction pathways governed by Ras, G-protein coupled receptors, and cAMP, and elucidate their different roles in development.

The autistic-like behaviors development during weaning and sexual maturation in VPA-induced autistic-like rats is accompanied by gut microbiota dysbiosis

Researches on gut microbiota in autism have mostly focused on children, but the dynamic changes of gut microbiota from weaning to adulthood were still not clear because of the difficulty of diagnosing autism. In this study, autistic-like rats indued by valproate (VPA) were tracked from weaning (end of breastfeeding; four weeks old) to sexual maturation (food; eight weeks old). Autistic-like rats were found to show obvious developmental disorders. During weaning, autistic-like rats only exhibited obvious repetitive stereotyped behaviors, but the autistic-like behaviors were fully apparent upon sexual maturation. Significant differences were observed between the gut microbiota of autistic-like and healthy rats across both age groups. The correlation analysis results revealed that the correlation between behaviors and some microbiota, especially Helicobacter, did not vary with age or diet. The total amount of short-chain fatty acids (SCFAs) decreased, butyric acid metabolism decreased, and propionic acid metabolism increased in the feces of autistic-like rats. The correlation between autistic-like behaviors and the butyric acid and propionic acid levels did not vary with diet or age. Inositol phosphate metabolism, amino acid metabolism, and lipopolysaccharide biosynthesis were significantly associated with autistic-like behaviors. Our results showed that although the microbiota and SCFAs related to autism were affected by age and diet, some remained consistent irrespective of age and diet, and they could be considered two of the factors related to autistic-like behaviors development.

Functional Gene and Metabolic Changes of Marine Microbial Populations Involved in Hydrocarbon Degradation Under Different Enrichment Conditions

In this study, seawater from the area of an oil extraction platform in Bohai Bay was subjected to experimental treatments with oil as the only carbon source to understand the transcriptional responses of seawater microbial populations to oil degradation treatments. Twelve enrichment conditions were used, and fluorescent in situ hybridization (FISH) along with metatranscriptomic analyses were used to understand functional changes within each treatment. RNA from the petroleum-degrading bacterial enrichments was extracted after cultivation and FISH was used to evaluate overall activity, while changes in gene expression among different culture conditions were analyzed based on eight hydrocarbon-specific gene probes and flow cytometry. Concomitantly, 1,066 metabolic pathways were identified as being expressed in the populations through RNA sequencing, metatranscriptomic analysis, and metabolic pathway enrichment analysis. The addition of oil led to the inhibition of carbohydrate metabolism and inositol phosphate metabolism, while also reducing extracellular signaling pathway transcription levels. When low- and high-nutrient conditions were compared, low-nutrient conditions inhibited taurine and hypotaurine metabolism in addition to inositol phosphate metabolism. Among oxygen-treated, carbon dioxide-treated, and air-treated conditions, oxygen-treated conditions inhibited taurine and hypotaurine metabolism but promoted galactose metabolism, while carbon dioxide-treated conditions promoted inositol phosphate metabolism. Overall, metabolic pathway expression and functional gene changes indicated that high-nutrient, oil-free, and aerobic culture conditions best promoted the growth and reproduction of marine microbial communities.