The strength of reproductive isolation often correlates positively with parental divergence in both animals and plants. Here, we assess the relationship between transmission ratio distortion (TRD) of ...marker loci and parental divergence in intraspecific rice (Oryza sativa L.) crosses. We produced 10 diverse F2 populations by crossing a temperate japonica reference accession with each of 10 donor accessions belonging to subpopulations different from the reference accession, and then genotyped the F2 populations using molecular markers distributed across the entire genome. Significant TRDs (α = 0.05) were detected in 9 of the 10 F2 populations. TRD regions on chromosomes 3 and 6 were common to several populations; in contrast, other TRD regions were unique to a single population, indicating the diversification of genomic location of TRDs among the populations. The level of TRD (estimated from the overall number and magnitude of TRDs) was significantly correlated with the genetic distance between the donor accessions and the reference accession. Our results suggest that in intraspecific rice crosses, parental divergence may result in diversification of the TRD pattern, followed by an increase in the level of TRD.
Suicide is an increasingly serious public health care concern worldwide. The impact of decreased in-house psychiatric resources on emergency care for suicidal patients has not been thoroughly ...examined. We evaluated the effects of closing an in-hospital psychiatric ward on the prehospital and emergency ward length of stay (LOS) and disposition location in patients who attempted suicide.This was a retrospective before-and-after study at a community emergency department (ED) in Japan. On March 31, 2014, the hospital closed its 50 psychiatric ward beds and outpatient consultation days were decreased from 5 to 2 days per week. Electronic health record data of suicidal patients who were brought to the ED were collected for 5 years before the decrease in in-hospital psychiatric services (April 1, 2009-March 31, 2014) and 5 years after the decrease (April 1, 2014-March 31, 2019). One-to-one propensity score matching was performed to compare prehospital and emergency ward LOS, and discharge location between the 2 groups.Of the 1083 eligible patients, 449 (41.5%) were brought to the ED after the closure of the psychiatric ward. Patients with older age, burns, and higher comorbidity index values, and those requiring endotracheal intubation, surgery, and emergency ward admission, were more likely to receive ED care after the psychiatric ward closure. In the propensity matched analysis with 418 pairs, the after-closure group showed a significant increase in median prehospital LOS (44.0 minutes vs 51.0 minutes, P < .001) and emergency ward LOS (3.0 days vs 4.0 days, P = .014) compared with the before-closure group. The rate of direct home return was significantly lower in the after-closure group compared with the before-closure group (87.1% vs 81.6%, odds ratio: 0.66; 95% confidence interval: 0.45-0.96).The prehospital and emergency ward LOS for patients who attempted suicide in the study site increased significantly after a decrease in hospital-based mental health services. Conversely, there was significant reduction in direct home discharge after the decrease in in-house psychiatric care. These results have important implications for future policy to address the increasing care needs of patients who attempt suicide.
IR64 is one of the world’s most popular rice cultivars. To collect genetic factors involved in controlling its heading date, we developed 70 reciprocal advanced-backcross populations with a total of ...6284 individuals at the BC4F2 generation from crosses between Koshihikari and IR64. We detected 29 QTLs associated with heading date on chromosomes 3, 5–8, 10, and 12. Twenty QTLs were located in the same chromosome regions as previously isolated heading date genes (Hd1, Hd6, Hd16, Ghd7, DTH8, Hd17, and Hd18). The rest were located in other chromosome regions. We found more number of QTLs than previous studies using mapping populations of IR64. Fine mapping in additional advanced-backcross populations clearly revealed that QTLs on the long arm of chromosome 7 are overlapping and seem to be a novel genetic factor for heading date because of their different locations from OsPRR37. Our results suggest that the difference in heading date between IR64 and Koshihikari is genetically controlled by many factors, and that a non-functional allele of Hd1 contributes to early heading of IR64 in the genetic background of functional alleles of other heading date QTLs and genes such as Hd6 and Hd16.
Many agronomic traits that are important in rice breeding are controlled by multiple genes. The extensive time and effort devoted so far to identifying and selecting such genes are still not enough ...to target multiple agronomic traits in practical breeding in Japan because of a lack of suitable plant materials in which to efficiently detect and validate beneficial alleles from diverse genetic resources. To facilitate the comprehensive analysis of genetic variation in agronomic traits among Asian cultivated rice, we developed 12 sets of chromosome segment substitution lines (CSSLs) with the japonica background, 11 of them in the same genetic background, using donors representing the genetic diversity of Asian cultivated rice. Using these materials, we overviewed the chromosomal locations of 1079 putative QTLs for seven agronomic traits and their allelic distribution in Asian cultivated rice through multiple linear regression analysis. The CSSLs will allow the effects of putative QTLs in the highly homogeneous japonica background to be validated.
The rice species Oryza sativa is considered to be a model plant because of its small genome size, extensive genetic map, relative ease of transformation and synteny with other cereal crops. Here we ...report the essentially complete sequence of chromosome 1, the longest chromosome in the rice genome. We summarize characteristics of the chromosome structure and the biological insight gained from the sequence. The analysis of 43.3 megabases (Mb) of non-overlapping sequence reveals 6,756 protein coding genes, of which 3,161 show homology to proteins of Arabidopsis thaliana, another model plant. About 30% (2,073) of the genes have been functionally categorized. Rice chromosome 1 is (G + C)-rich, especially in its coding regions, and is characterized by several gene families that are dispersed or arranged in tandem repeats. Comparison with a draft sequence indicates the importance of a high-quality finished sequence.
To determine the chromosomal positions of expressed rice genes, we have performed an expressed sequence tag (EST) mapping project by polymerase chain reaction-based yeast artificial chromosome (YAC) ...screening. Specific primers designed from 6713 unique EST sequences derived from 19 cDNA libraries were screened on 4387 YAC clones and used for map construction in combination with genetic analysis. Here, we describe the establishment of a comprehensive YAC-based rice transcript map that contains 6591 EST sites and covers 80.8% of the rice genome. Chromosomes 1, 2, and 3 have relatively high EST densities, approximately twice those of chromosomes 11 and 12, and contain 41% of the total EST sites on the map. Most of the EST-dense regions are distributed on the distal regions of each chromosome arm. Genomic regions flanking the centromeres for most of the chromosomes have lower EST density. Recombination frequency in these regions is suppressed significantly. Our EST mapping also shows that 40% of the assigned ESTs occupy only ∼21% of the entire genome. The rice transcript map has been a valuable resource for genetic study, gene isolation, and genome sequencing at the Rice Genome Research Program and should become an important tool for comparative analysis of chromosome structure and evolution among the cereals.
The strength of reproductive isolation is often positively correlated with parental divergence in both animals and plants. We here assessed the pattern of transmission ratio distortion (TRD) in ...intraspecific crosses of rice (Oryza sativa L.). Our study suggested at least two important results: (1) Parental divergence appears to result in diversification of genomic location of TRDs. (2) The level of TRD increases with parental divergence. We also discuss the possible genetic mechanisms underlying the TRD observed in this study.
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