Direct precision frequency measurement and correction technology with double ADC

A new method of direct precision frequency measurement is proposed in this paper, which uses the clock cursor effect between the sampling clock signal and input signal and ADC (analog to digital converter) quantization error suppression technique in the background of digital measurement with double ADC. On this basis, a precision frequency corrector is designed. Compared with the traditional frequency synthesizer, this device takes the non-standard frequency signal of the crystal oscillator as the reference to realize the standard frequency signal output through the frequency correction function. Meanwhile, the output signal is obviously narrower in range, from 0.0001 Hz to 0.1 Hz. The frequency corrector can also realize the second stability of less than 3 × 10^-12 and a small frequency correction of 10^-11 orders of magnitude.

Comparative study between Ephedra sinica Stapf and Fructus Schisandrae Chinensis on ET-1 and 6-keto-prostaglandin F1α in rats with idiopathic pulmonary fibrosis

The aim of this study was to evaluate differences in the effects of Ephedra sinica Stapf and Fructus Schisandrae Chinensis on angiogenesis in the treatment of bleomycin-induced rat idiopathic pulmonary fibrosis. The rat models were created using bleomycin. The animals were divided into six groups: model, control, Ephedra alone, Schisandrae alone, combination of Ephedra and Schisandrae, and hydrocortisone alone. The treatments were administered for 28 days. After 7 and 28 days, the rats were sacrificed for pathological morphology examination, microvascular density determination, and angiogenesis-related cytokine examination. The Ephedra and hydrocortisone groups demonstrated significantly reduced alveolitis and pulmonary fibrosis grades compared with the model group (P < 0.05). The number of blood vessels in the Ephedra group was higher than that in the Schisandrae and combination therapy groups. At 7 days, the expression level of endothelin (ET)-1 in the model group was significantly higher than that in the normal group (P < 0.01). The level of 6-keto-prostaglandin F1α (6-keto-PGF1α) in the treatment group increased, and there were significant differences between the Ephedra group and the combination therapy and normal groups (P < 0.05). Ephedra inhibited the increase in the lung coefficient. The combination therapy prevented pulmonary artery injury and angiogenesis of the arteries by reducing the level of ET-1 and promoting the level of 6-keto-PGF1α in the blood. Ephedra and Schisandrae prevented alveolitis and the development of pulmonary fibrosis.

Heading date gene, dth3 controlled late flowering in O. Glaberrima Steud. by down-regulating Ehd1

Heading date in rice is an important agronomic trait controlled by several genes. In this study, flowering time of variety Dianjingyou 1 (DJY1) was earlier than a near-isogenic line (named NIL) carried chromosome segment from African rice on chromosome 3S, when grown in both long-day (LD) and short-day (SD) conditions. By analyzing a large F2 population from NIL × DJY1, the locus DTH3 (QTL for days to heading on chromosome 3) controlling early heading date in DJY1 was fine mapped to a 64-kb segment which contained only one annotated gene, a MIKC-type MADS-box protein. We detected a 6-bp deletion and a single base substitution in the C-domain by sequencing DTH3 in DJY1 compared with dth3 in NIL, and overexpression of DTH3 caused early flowering in callus. Quantitative real-time PCR revealed that the transcript level of dth3 in NIL was lower than that DTH3 in DJY1 in both LD and SD conditions. The Early heading date 1 (Ehd1) which promotes the RFT1, was up-regulated by DTH3 in both LD and SD conditions. Based on Indel and dCAPs marker analysis, the dth3 allele was only present in African rice accessions. A phylogenetic analysis based on microsatellite genotyping suggested that African rice had a close genetic relationship to O. rufipogon and O. latifolia, and was similar to japonica cultivars. DTH3 affected flowering time and had no significant effect on the main agronomic traits.

The genetic basic and fine-mapping of a stable quantitative-trait loci for aluminium tolerance in rice

Aluminium (Al) toxicity is a primary cause of low rice productivity in acid soils. We have mapped a number of quantitative-trait loci (QTL) controlling Al tolerance in a recombinant inbred line population derived from a cross between the tolerant japonica cultivar Asominori and the sensitive indica cultivar IR24. Tolerance was assessed on the basis of relative root elongation. QTL were detected on chromosomes 1, 9, and 11, with the percentages of phenotypic variance explained ranging from 13.5 to 17.7%. Alleles from Asominori at all three QTL were associated with increased Al tolerance. qRRE-9 is expressed both in the genetic background of IR24 and in an Asominori/IR24-mixed background. qRRE-9 was reduced to the single recessive Mendelian factor Alt-9. High-resolution genetic and physical maps were constructed for Alt-9 in a BC(3)F(2) population of 1,043 individuals. Alt-9 maps between RM24702 and ID47-2 on chromosome 9, and co-segregates with RM5765.

QTL analysis for rice grain length and fine mapping of an identified QTL with stable and major effects

Grain length in rice plays an important role in determining rice appearance, milling, cooking and eating quality. In this study, the genetic basis of grain length was dissected into six main-effect quantitative trait loci (QTLs) and twelve pairs of epistatic QTLs. The stability of these QTLs was evaluated in four environments using an F7 recombinant inbred line (RIL) population derived from the cross between a Japonica variety, Asominori, and an Indica variety, IR24. Moreover, chromosome segment substitution lines (CSSLs) harboring each of the six main-effect QTLs were used to evaluate gene action of QTLs across eight environments. A major QTL denoted as qGL-3a, was found to express stably not only in the isogenic background of Asominori but also in the recombinant background of Asominori and IR24 under multiple environments. The IR24 allele at qGL-3a has a positive effect on grain length. Based on the test of advanced backcross progenies, qGL-3a was dissected as a single Mendelian factor, i.e., long rice grain was controlled by a recessive gene gl-3. High-resolution genetic and physical maps were further constructed for fine mapping gl-3 by using 11 simple sequence repeat (SSR) markers designed using sequence information from seven BAC/PAC clones and a BC4F2 population consisting of 2,068 individuals. Consequently, the gl-3 gene was narrowed down to a candidate genomic region of 87.5 kb long defined by SSR markers RMw357 and RMw353 on chromosome 3, which provides a basis for map-based cloning of this gene and for marker-aided QTL pyramiding in rice quality breeding.

Stability of QTLs for rice grain dimension and endosperm chalkiness characteristics across eight environments

Rice appearance quality, including traits specifying grain dimension and endosperm chalkiness, represents a major problem in many rice-producing areas of the world. In this study, the genetic basis of six appearance quality traits of milled rice was dissected into quantitative trait loci (QTL) main effects, and the stability of these QTLs was assessed in a population of 66 chromosome segment substitution lines (CSSLs) across eight environments. The CSSLs showed transgressive segregation for many of the traits, and significant correlations were detected among most of the traits. Twenty-two QTLs were identified on eight chromosomes, and numerous QTLs affecting related traits were mapped in the same regions, probably reflecting pleiotropic effects. Nine QTLs, namely qGL-1,qGL-3, qGW-5,qLWR-3, qLWR-5,qPGWC-8, qPGWC-9, qACE-8, and qDEC-8, were consistently detected across the eight environments. The additive main effect and multiplicative interaction (AMMI) analysis showed that genotype (G) x environment (E) interaction was significant for all six traits, with the first three iPCA terms accounting for over 80% of the G x E variance. Both D(I) values and the iPCA1-iPCA2 biplots showed that the CSSLs harboring the nine QTL alleles were more stable than those carrying any of the additional 13 QTL alleles, thereby confirming their environmental stability and pointing to their appropriateness as targets for marker-assisted selection for high-quality rice varieties.

[Analysis of heading time genotype for a rice male sterile line Zhenshan 97A]

Zhenshan 97A, a rice male sterile, were applied widely since the release of hybrid rice in 1973 in China, but the genotype of heading time in this sterile line was still unknown. This definitely limited the further use of this sterile line in breeding practice and re-production of hybrid seeds. To solve this problem, we analyzed the segregation pattern of phenotype of heading time in progenies from crosses between Zhenshan 97A and four tester cultivars, Akihikari (e1e1e2e2e3e3 Se-1eSe-1e), Koshihikari (E1E1E2E2e3e3Se-1eSe-1e), Nipponbare (E1E1e2e2e3e3Se-1Se-1) and Hinohikari (E1E1E2E2e3e3Se-1Se-1), whose genotypes of heading time were already known. The results showed that the genotype of heading time in Zhenshan 97A was e1e1e2e2E3E3Se-1Se-1 and it also carried a recessive inhibitor i-Se-1 for phtoperiod-sensitivity. Meanwhile, a major photoperiod-sensitive dominant genes Se-1 and other modified photoperiod-sensitive genes: i-Se-1, E3, Hd3(En-Se-1), Hd5 and Hd6, were identified in Zhenshan 97A by crossing with QTL nearly isogenic lines: NIL (Hd1), NIL (Hd2), NIL(Hd3), NIL(Hd5) and NIL(Hd6).