Genes & genetic systems最新文献

Centromeres are essential for chromosome segregation, yet they are among the most rapidly evolving regions of the genome. The mechanisms driving this rapid evolution of centromeric sequences are still not well understood. In this study, we identified the centromeric sequences of a wheat-infecting Pyricularia oryzae strain (Br48) using CENP-A chromatin immunoprecipitation followed by high-throughput sequencing. The Br48 centromeres range from 71 kb to 101 kb in length and are highly AT-rich (72.1-75.5%) and repeat-rich (63.4-85.0%). These regions are also enriched in H3K9me3 and 5-methylcytosine but depleted of H3K4me2 and H3K27me3. During the analysis of repetitive sequences in the Br48 centromere, we identified a stretch of approximately 530 bp that is tightly associated with centromeres in the Pyricularia fungus. We designated this element as the centromere-associated IR element (CenIR), as it often forms inverted repeat structures with two elements adjacent in reverse orientation. A comparison of putative centromere sequences across phylogenetically distinct P. oryzae strains suggests that changes in centromeric sequences are non-uniform across chromosomes and do not always align with the fungal phylogenetic relationships. Repeat-induced point mutation (RIP)-like CG to TA transitions likely accelerate base substitutions in the centromeres of Pyricularia fungi.

In our study, we aimed to identify new mutants resulting from ONSEN transposition in Arabidopsis thaliana by subjecting nrpd1 mutants to heat stress. We isolated a mutant with a significantly elongated hypocotyl, named "Long hypocotyl in ONSEN inserted line 1" (HYO1). This phenotype was heritable, with progeny consistently displaying longer hypocotyls than the wild type. Genetic analysis revealed that this trait was due to a single recessive mutation. Further mapping and sequencing identified the insertion of ONSEN in the HY2 gene, a crucial regulator of hypocotyl elongation. The insertion disrupted HY2 transcription, as confirmed by quantitative PCR, leading to the observed phenotype. To assess the influence of the nrpd1 background, we generated lines backcrossed twice to wild-type Col-0, and the results were consistent with those observed in the original mutant lines. Furthermore, we examined the effect of HY2 and HYO1 mutations on flowering time by analyzing the expression levels of FT. The hyo1 mutant exhibited earlier flowering compared to both the wild type and nrpd1 mutants, with increased FT expression levels. This research underscores the significant impact of ONSEN transposition on gene function and phenotypic variation in Arabidopsis thaliana, providing new insights into the mutagenic potential of transposons and their role in shaping plant traits.

A 1.5 to 3 Mb microdeletion of chromosome 22q11.2 with loss of multiple genes including histone cell cycle regulator (HIRA) causes 22q11.2 deletion syndrome (22q11.2 DS), a common disorder with variable manifestations including congenital malformations affecting the heart, palate and kidneys in association with neurodevelopmental, psychiatric, endocrine and autoimmune abnormalities. The aim of this study was to develop a TaqMan based dosage analysis PCR (TaqMan qPCR) for use as a rapid, cost-effective test for clinically suspected patients fulfilling previously described criteria for molecular diagnosis of 22q11.2 DS in a lower middle-income country where the cost of testing limits its use in routine clinical practice. Nineteen patients were recruited with informed consent following ethical approval from the Ethics Review Committee (ERC), Lady Ridgway hospital, Colombo. Dosage analysis of extracted DNA was performed using a TaqMan qPCR assay by amplifying regions within the target (HIRA) and control [Testin LIM domain protein (TES)] genes of a suspected patient (P) and unaffected person (N). For detection of a deletion, the normalized values (HIRA / TES dosage) of a patient were compared with normalized values of an unaffected person. A ratio of P:N of 0.5 confirmed presence of a deletion while a ratio of 1.0 refuted this. Seven of 19 (37%) cases were confirmed to have a HIRA deletion, confirming the diagnosis of 22q11.2 DS, with these results being in complete agreement with those of fluorescence in-situ hybridization (FISH), (performed in 9/19 (47.3%) of recruited cases) and whole exome sequencing (WES) (all 19 samples tested). This TaqMan qPCR assay was able to reliably distinguish HIRA deleted cases from the non-deleted ones. The assay was both less expensive and faster compared to commercially available alternatives in our setting, including FISH and multiple ligation-dependent probe amplification (MLPA).

The mitochondrial cytochrome b gene (Cytb) of the Japanese field vole (Microtus montebelli), an herbivorous rodent, was subjected to an analysis of sequence variation with the objective of elucidating the population histories of this species. Construction of a phylogenetic tree revealed the existence of several region-specific lineages in Honshu and Kyushu, which were evenly separated from each other. In consideration of the documented time-dependent evolutionary rates of rodents, the estimated divergence times indicate that the region-specific lineages of M. montebelli emerged 160,000-300,000 years ago. In a haplotype network, the region-specific lineages from northern and central Honshu tended to show star-shaped clusters, with additional internal star-shaped clusters, indicative of two periods of population expansion. The onsets of these expansions were estimated to have occurred 15,000 and 10,000 years ago, respectively, suggestive of association with the two periods of rapid warming following the last glacial maximum (LGM). In contrast, such predicted post-LGM expansion events were less pronounced in the southern lineages, implying latitudinal dependence of the effect of the LGM on population dynamics. Sado Island haplotypes exhibited a network with a star-shaped pattern and a 10,000-year-old expansion signal, surrounded by a Honshu haplotype cluster with a 15,000-year-old expansion signal, suggesting that post-LGM expansion events contributed to the formation of the Sado population. A reanalysis of Cytb sequences of the Japanese hare (Lepus brachyurus), which has a similar geographic range to the voles, yielded results that were consistent with those of the vole analysis, confirming that the characteristics of the post-LGM expansion event were dependent on latitude, involved two successive expansion events, and enabled migration across deep straits. It seems reasonable to infer that the environmental changes that occurred during the warm periods following the LGM were a contributing factor in the expansion of the distribution range of newly emerged haplotype groups.

The sequencing of PCR fragments amplified from specific regions of genomes is a fundamental technique in molecular genetics. Sanger sequencing is commonly used for this analysis; however, amplicon sequencing utilizing next-generation sequencing has become widespread. In addition, long-read amplicon sequencing, using Nanopore or PacBio sequencers to analyze long PCR fragments, has emerged, although it is often more expensive than Sanger sequencing. Recently, low-cost commercial services for full-length plasmid DNA sequencing using Nanopore sequencers have been launched in several countries, including Japan. This study explored the potential of these services to sequence long PCR fragments without the need for cloning into plasmid DNA, as cloning long PCR fragments or blunt-end PCR fragments into plasmids is often challenging. PCR fragments of 4-11 kb, amplified from the DFR-B gene involved in the biosynthesis of anthocyanin, with or without Tpn1 transposons in Japanese morning glory (Ipomoea nil), were circularized using T4 DNA ligase and analyzed as templates. Although some inaccuracies in the length of homopolymer stretches were observed, the remaining sequences were obtained without significant errors. This method could potentially reduce the labor and costs associated with cloning, primer synthesis and sequence assembly, thus making it a viable option for the analysis of long PCR fragment sequences. Moreover, this study reconfirmed that Tpn1 transposons are major mutagens in I. nil and demonstrated their transposition in the Violet line, a long-used standard in plant physiology.

Next-generation RNA sequencing analysis was performed to develop 13 novel expressed sequence tag-simple sequence repeat markers to evaluate the genetic variation in the near-threatened halophyte Limonium tetragonum (Thunb.) A. A. Bullock. In the four populations examined, the total number of alleles at each locus ranged from two to seven, with an average of 3.1. The average observed and expected heterozygosity ranged from 0.00 to 0.13 and 0.28 to 0.78, respectively. Three of the 13 loci had the same homozygous alleles within populations, but different alleles among populations. Compared to other halophytes, relatively low genetic diversity was observed in this species. Further studies are necessary to determine the population demography of L. tetragonum and to clarify the cause of its low genetic diversity.

Next-generation sequencing (NGS) has become widely available and is routinely used in basic research and clinical practice. The reference genome sequence is an essential resource for NGS analysis, and several population-specific reference genomes have recently been constructed to provide a choice to deal with the vast genetic diversity of human samples. However, resources supporting population-specific references are insufficient, and it is burdensome to perform analysis using these reference genomes. Here, we constructed a set of resources to support NGS analysis using the Japanese reference genome, JG. We created resources for variant calling, variant effect prediction, gene and repeat element annotations, read mappability and RNA-seq analysis. We also provide a resource for reference coordinate conversion for further annotation enrichment. We then provide a variant calling protocol with JG. Our resources provide a guide to prepare sufficient resources for the use of population-specific reference genomes and can facilitate the migration of reference genomes.

Nucleosomes are complexes of DNA and histone proteins that form the basis of eukaryotic chromatin. Eukaryotic histones are descended from Archaean homologs; however, how this occurred remains unclear. Our previous genetic analysis on the budding yeast nucleosome identified 26 histone residues conserved between S. cerevisiae and T. brucei; 15 that are lethal when mutated and 11 that are synthetically lethal with deletion of the FEN1 nuclease. These residues are partially conserved in nucleosomes of a variety of giant viruses, allowing us to follow the route by which they were established in the LECA (Last Eukaryote Common Ancestor). We analyzed yeast nucleosome genetic data to generate a model for the emergence of the eukaryotic nucleosome. In our model, histone H2B-H2A and H4-H3 doublets found in giant virus nucleosomes facilitated the formation of the acidic patch surface and nucleosome entry sites of the eukaryotic nucleosome, respectively. Splitting of the H2B-H2A doublet resulted in the H2A variant, H2A.Z., and subsequent splitting of the H4-H3 doublet led to a eukaryotic specific domain required for chromatin binding of H2A.Z. We propose that the LECA emerged when the newly-split H3 N-terminal horizontally acquired a common N-tail found in extinct pre-LECA lineages and some extant giant viruses. This hypothesis predicts that the emergence of the H3 variant CENP-A and establishment of CENP-A-dependent chromosome segregation occurred after the emergence of the LECA, implying that the root of all eukaryotes is assigned within Euglenida.

Strict control of the expression levels of heterologously introduced protein-coding genes is important for the functional analysis of the protein of interest and its effective use in new situations. For this purpose, various promoters with different expression strengths, codon optimization, and expression stimulation by low molecular weight compounds are commonly used. However, methods to control protein expression levels by combining regulation of translation efficiency have not been studied in detail. We previously observed relatively high basal expression of Cre, when it was heterologously expressed in fission yeast. Here, we used a fission yeast strain that is susceptible to centromere disruption and thus highly sensitive to Cre levels and report successful fine-tuning of heterologous Cre expression by modulating the Cre translation efficiency. To inhibit Cre translation initiation, we generated two mutations in the 5' untranslated region of the Cre mRNAs which both interfered with the scanning process of start codon recognition, mediated by the specialized ribosomal subunits. These mutations successfully reduced the levels of exogenously expressed Cre to different degrees in fission yeast. Combining them with different promoter strengths allowed us to conduct centromere-disruption experiments in fission yeast. Our data indicate that modification of translational control is an additional tool in heterologous gene expression.

Background: β-sitosterol is a natural plant steroidal compound with anti-cancer properties against various tumors. This work attempts to explore the inhibitory effect of β-sitosterol on the progression of lung adenocarcinoma (LUAD) and further analyze its targets.

Methods: In this work, we applied network pharmacology to obtain the components and targets of Ganoderma spore powder. The biological functions of β-sitosterol and CHRM2 were studied using the homograft mouse model and a series of in vitro experiments including quantitative reverse transcription polymerase chain reaction (qRT-PCR), western blot (WB), CCK-8, flow cytometry, immunohistochemistry (IHC), and immunofluorescence (IF) experiments. The regulatory influence of β-sitosterol on the glycolysis pathway was validated by detecting glucose consumption and lactate production, as well as extracellular acidification rate (ECAR) and oxygen consumption rate (OCR).

Results: In this project, we unearthed that CHRM2 was a protein that directly binds to β-sitosterol. In vitro, CHRM2 overexpression repressed the apoptosis rate and expression of apoptosis-related proteins and promoted glycolysis, while the addition of lonidamine attenuated the inhibitory effect conferred by CHRM2 overexpression on LUAD apoptosis. Furthermore, β-sitosterol hindered glycolysis as well as the growth of tumors in vitro and in vivo. CHRM2 overexpression reversed the effect of β-sitosterol on the biological behavior of LUAD cells.

Conclusion: Our project emphasized that CHRM2 is a direct target of β-sitosterol in LUAD cells. β-sitosterol can repress the glycolysis pathway, exerting an anti-tumor effect. These findings can provide new evidence for supporting the potential use of β-sitosterol as a therapeutic agent for LUAD.