Biology subjects

Kazama, Y.

Publications and source records attributed to Kazama, Y..

4 recordsLinked to original sources

bioRxiv2025

Arabidopsis aneuploidy mutant C30-81-as6, possesses enormous variations in multiple phenotypic characteristics.

Heavy-ion beam irradiation can be recognized as one of the powerful mutagenesis techniques because it induces high mutation frequency, minimal damage to the other traits and the possibility of having large DNA fragmental mutations. Aneuploid cells may have an additional or fewer number of chromosomes compared to their wild-type. The mutant line of C30-81-as6 is an ion beam-generated, Arabidopsis Col-0 based, aneuploid mutant line confirmed by whole genome sequence analysis, DNA quantity measurement using flow cytometry analysis and microscopic observations of additional chromosome. The mutant shows abnormal leaf shapes, petioleless rosette leaves, elevated trichome bases and later flowering phenotypes. Segregation analysis confirmed that additional DNA amount is correlated with observed phenotype since mutants showing intermediate phenotype possess moderate DNA quantities. A set of candidate causal genes was identified using up and downregulated differentially expressed genes in transcriptome analysis. Gene ontology analysis further supports mutant phenotypic characteristics and provides insights into its functional priorities, including promotion of cellular structure and energy production. Meanwhile, the downregulation of senescence-related gene ontology terms validates its extended vegetative phase. The whole genome sequence analysis based chromosome rearrangement prediction and the gene density mapping of upregulated DEGs, suggested that the long arm of chromosome 2 is a main component of the additional chromosome. In addition, the phenotype of C30-81-as6 largely resembles Arabidopsis additional chromosome 2 containing aneuploidy mutant. The ion beam mutagenesis generated aneuploidy mutant that may possess a fused DNA fragmented chromosome and it may successfully challenge the wild-type plants for establishment in nature.

genetics↗

bioRxiv2024

Effect of heterozygous deletions on phenotypic changes and dosage compensation in Arabidopsis thaliana

Heterozygous deletions, which include a large number of genes, are often caused by the induction of mutations. The induction of gene dosage compensation should be considered when assessing the effects of heterozygous deletions on phenotypic changes. This mechanism is known to balance the expression levels of genes with different copy numbers in sex chromosomes, but it is also known to operate in autosomes. In the present study, 12 Arabidopsis thaliana BC1 mutants with heterozygous deletions were produced by crossing wild-type Col-0 plants with mutants induced by heavy ion beams. The sizes of the deletions ranged from 50.9 kb to 2.03 Mb, and the number of deleted genes ranged from 8 to 92. Nine of the 12 BC1 mutants showed phenotypic changes in fresh weight 14 days after cultivation or during the flowering period. RNA-sequencing (RNA-seq) analyses of 14-day-old leaves, 40-day-old leaves, and flower buds showed that dosage compensation did not occur in any stage or tissue tested. These results indicate that heterozygous deletions cause phenotypic changes owing to the absence of dosage compensation. Article SummaryIn this study, we examined the impact of heterozygous deletions in Arabidopsis thaliana. By crossing wild-type Col-0 plants with mutants induced by heavy ion beams, we created 12 BC1 mutants, each having heterozygous deletions. The deletions ranged from 50.9 kb to 2.03 Mb, affecting 8 to 92 genes. Nine mutants showed changes in fresh weight or flowering time. RNA-seq analyses of leaves and flower buds revealed no gene dosage compensation. Our findings indicate that phenotypic changes result from the lack of dosage compensation in heterozygous deletions.

genetics↗

bioRxiv2021

Region-specific maladaptive gray matter myelination is associated with differential susceptibility to stress-induced behavior in male rodents and humans

Individual reactions to traumatic stress vary dramatically, yet the biological basis of this variation remains poorly understood. Recent studies demonstrate the surprising plasticity of oligodendrocytes and myelin with stress and experience, providing a potential mechanism by which trauma induces aberrant structural and functional changes in the adult brain. In this study, we utilized a translational approach to test the hypothesis that gray matter myelin contributes to traumatic-stress-induced behavioral variation in both rats and humans. We exposed adult, male rats to a single, severe stressor and used a multimodal approach to characterize avoidance, startle, and fear-learning behavior, as well as oligodendrocyte and myelin content in multiple brain areas. We found that oligodendrocyte cell density and myelin content were correlated with behavioral outcomes in a region-specific manner. Specifically, stress-induced avoidance positively correlated with hippocampal dentate gyrus oligodendrocytes and myelin. Viral overexpression of the oligodendrogenic factor Olig1 in the dentate gyrus was sufficient to induce an anxiety-like behavioral phenotype. In contrast, contextual fear learning positively correlated with myelin in the amygdala and spatial processing regions of the hippocampus. In a group of trauma-exposed US veterans, T1-/T2-weighted magnetic resonance imaging estimates of hippocampal and amygdala myelin associated with symptom profiles in a region-specific manner that mirrored the findings in rats. These results demonstrate a species- independent relationship between region-specific, gray matter oligodendrocytes and myelin and differential behavioral phenotypes following traumatic stress exposure. This study suggests a novel mechanism for brain plasticity that underlies individual variance in sensitivity to traumatic stress.

neuroscience↗

bioRxiv2019

An asexual flower of Silene latifolia and Microbotryum lychnidis-dioicae promoting its sexual-organ development

Silene latifolia is a dioecious flowering plant with sex chromosomes in the family Caryophyllaceae. Development of a gynoecium and stamens are suppressed in the male and female flowers of S. latifolia, respectively. Microbtryum lychnidis-dioicae promotes stamen development when it infects the female flower. If suppression of the stamen and gynoecium development is regulated by the same mechanism, suppression of gynoecium and stamen development is released simultaneously with the infection by M. lychnidis-dioicae. To assess this hypothesis, an asexual mutant, without gynoecium or stamen, was infected with M. lychnidis-dioicae. A filament of the stamen in the infected asexual mutant was elongated at stages 11 and 12 of the flower bud development as well as the male, but the gynoecium did not form. Instead of the gynoecium, a filamentous structure was suppressed as in the male flower. Developmental suppression of the stamen was released by M. lychnidis-dioicae, but that of gynoecium development was not released. It is thought, therefore, that the suppression of gynoecium development was not released by the infection of M. lychnidis-dioicae. M. lychnidis-dioicae would have a function similar to SPF since the elongation of the stamen that is not observed in the healthy asexual mutant was observed after stage 8 of flower bud development. Such an infection experiment also that the Y chromosome of the asexual mutant has genes related to the differentiation of archesporial cells, but none related to maturation of the tapetal cells.

plant biology↗