Research of Fluridone's Effects on Growth and Pigment Accumulation of Haematococcus pluvialis Based on Transcriptome Sequencing

Haematococcus pluvialis has high economic value because of its high astaxanthin-producing ability. The mutation breeding of Haematococcus pluvialis is an important method to improve the yield of astaxanthin. Fluoridone, an inhibitor of phytoene dehydrogenase, can be used as a screening reagent for mutation breeding of Haematococcus pluvialis. This study describes the effect of fluridone on the biomass, chlorophyll, and astaxanthin content of Haematococcus pluvialis at different growth stages. Five fluridone concentrations (0.00 mg/L, 0.25 mg/L, 0.50 mg/L, 1.00 mg/L, and 2.00 mg/L) were set to treat Haematococcus pluvialis. It was found that fluridone significantly inhibited the growth and accumulation of astaxanthin in the red dormant stage. In addition, transcriptome sequencing was used to analyze the expression of genes related to four metabolic pathways in photosynthesis, carotenoid synthesis, fatty acid metabolism, and cellular antioxidant in algae after fluridone treatment. The results showed that six genes related to photosynthesis were downregulated. FPPS, lcyB genes related to carotenoid synthesis are downregulated, but carotenoid β-cyclic hydroxylase gene (LUT5), which plays a role in the conversion of carotenoid to abscisic acid (ABA), was upregulated, while the expression of phytoene dehydrogenase gene did not change. Two genes related to cell antioxidant capacity were upregulated. In the fatty acid metabolism pathway, the acetyl-CoA carboxylase gene (ACACA) was downregulated in the green stage, but upregulated in the red stage, and the stearoyl-CoA desaturase gene (SAD) was upregulated. According to the transcriptome results, fluridone can affect the astaxanthin accumulation and growth of Haematococcus pluvialis by regulating the synthesis of carotenoids, chlorophyll, fatty acids, and so on. It is expected to be used as a screening agent for the breeding of Haematococcus pluvialis. This research also provides an experimental basis for research on the mechanism of astaxanthin metabolism in Haematococcus pluvialis.

Characterization of deoxyribonucleic methylation and transcript abundance of sex-related genes during tempera ture-dependent sex determination in Mauremys reevesii†

A number of genes relevant for sex determination have been found in species with temperature-dependent sex determination. Epigenetics play a key role in sex determination, but characterization of deoxyribonucleic acid methylation of sex-related genes on temperature-dependent sex determination remains unclear. Mauremys reevesii is a typical species with temperature-dependent sex determination. In this study, we analyzed the Cytosine Guanine (CpG) methylation status of the proximal promoters, the messenger ribonucleic acid expression patterns and the correlation between methylation and expression levels of Aromatase, Forkhead box protein L2, Doublesex and mab3-related transcription factor 1, sex-determining region on Y chromosome-box 9, and anti-Müllerian hormone, which are key genes in sex determination in other species. We also analyzed the expression level of genes that encode enzymes involved in methylation and demethylation. The expression levels of Aromatase and Forkhead box protein L2 at the female producing temperature were higher than those at the male producing temperature; the expression levels of Doublesex and mab3-related transcription factor 1, sex-determining region on Y chromosome-box 9, and anti-Müllerian hormone were higher at MPT. The expression of some genes involved in methylation and demethylation is significantly different between male producing temperature and female producing temperature. The expression of messenger ribonucleic acid of genes involved in deoxyribonucleic acid methylation and demethylation affected by temperature, together with other factors, may change the methylation level of the regulatory regions of sex-related genes, which may further lead to temperature-specific expression of sex-related genes, and eventually affect the differentiation of the gonads.

Transcriptome sequencing and comparative analysis of adult ovary and testis identify potential gonadal maintenance-related genes in Mauremys reevesii with temperature-dependent sex determination

Mauremys reevesii is a classical organism with temperature-dependent sex determination (TSD). Gonad development in early life has recently received considerable attention but gonadal maintenance after sex differentiation in turtles with TSD remains a mystery. In this study, we sequenced the transcriptomes for the adult testis and ovary using RNA-seq, and 36,221 transcripts were identified. In total, 1,594 differentially expressed genes (DEGs) were identified where 756 DEGs were upregulated in the testis and 838 DEGs were upregulated in the ovary. Gene Ontology and Kyoto Encyclopedia of Genes and Genomes pathway analysis suggested that the TGF-beta signaling pathway and Hedgehog signaling pathway have important roles in testis maintenance and spermatogenesis, whereas the Hippo signaling pathway and Wnt signaling pathway are likely to participate in ovary maintenance. We determined the existence of antagonistic networks containing significant specific-expressed genes and pathways related to gonadal maintenance and gametogenesis in the adult gonads of M. reevesii. The candidate gene Fibronectin type 3 and ankyrin repeat domains 1 (FANK1) might be involved with the regulation of testis spermatogenesis.

Single-molecule long-read transcriptome profiling of Platysternon megacephalum mitochondrial genome with gene rearrangement and control region duplication

Platysternon megacephalum is the sole living representative of the poorly studied turtle lineage Platysternidae. Their mitochondrial genome has been subject to gene rearrangement and control region duplication, resulting in a unique mitochondrial gene order in vertebrates. In this study, we sequenced the first full-length turtle (P. megacephalum) liver transcriptome using single-molecule real-time sequencing to study the transcriptional mechanisms of its mitochondrial genome. ND5 and ND6 anti-sense (ND6AS) forms a single transcript with the same expression in the human mitochondrial genome, but here we demonstrated differential expression of the rearranged ND5 and ND6AS genes in P. megacephalum. And some polycistronic transcripts were also reported in this study. Notably, we detected some novel long non-coding RNAs with alternative polyadenylation from the duplicated control region, and a novel ND6AS transcript composed of a long non-coding sequence, ND6AS, and tRNA-GluAS. These results provide the first description of a mtDNA transcriptome with gene rearrangement and control region duplication. These findings further our understanding of the fundamental concepts of mitochondrial gene transcription and RNA processing, and provide a new insight into the mechanism of transcription regulation of the mitochondrial genome.

miR-21-5p induces cell proliferation by targeting TGFBI in non-small cell lung cancer cells

The mortality rate of non-small cell lung cancer (NSCLC) remains high worldwide. miR-21-5p plays an important part in many cancer types, including NSCLC. However, the effect of miR-21-5p in NSCLC tumorigenesis remains poorly understood. The present study investigated whether miR-21-5p promoted NSCLC cell proliferation in vitro. In order to study the molecular mechanism by which miR-21-5p contributes to NSCLC progression, three bioinformatics algorithms were used to predict the genes which miR-21-5p targeted. TGFBI was identfieid as a putative direct target in NSCLC cells via the luciferase reporter assay. Furthermore, miR-21-5p downregulated TGFBI protein expression by a post-transcriptional mechanism via western blotting and a reverse transcription-quantitative polymerase chain reaction analysis. Finally, TGFBI exhibited opposing effects to those of miR-21-5p on NSCLC cells, suggesting that miR-21-5p may promote cell proliferation by negative regulation of TGFBI. These results suggest miR-21-5p promote the proliferation of NSCLC cells via inhibiting TGFBI expression.

Complete mitochondrial genome of the Cyclemys pulchristriata (Chelonia: Geoemydidae)

In this study, we obtained complete mitochondrial genome sequence of Cyclemys pulchristriata. The mitochondrial genome reaches a length of 16,527 bp, containing 13 protein-coding genes (PCGs), 22tRNA genes, 2 rRNA genes and 1 control region. All protein-coding genes initiate with ATG as start codon, except for CO1 started with GTG. Most protein-coding genes ended by TAA as stop codon. Interestingly, there is an extra nucleotide A insertion in ND3 gene in C. pulchristriata. This study provides information on the genetic resources of C. pulchristriata that will contribute to protect this species.