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Culm length (CL) is composed of different elongated internode lengths (EILs) and is closely correlated to the lodging resistance in rice (Oryza sativa L.). The objective of this study was to identify quantitative trait loci (QTLs) stably associated with CL and the first to fourth EIL from panicle base, which were abbreviated as FIL (first), SIL (second), TIL (third), and FOIL (fourth) in japonica rice, respectively. Association mapping was conducted using the genotypes determined by 154 simple sequence repeat markers and the phenotypes in 2010, 2011, and 2015 of 331 japonica rice accessions. The study mapped 6, 5, 15, 2, and 2 QTLs tagged by 22 markers on eight chromosomes and stably associated with CL, FIL, SIL, TIL, and FOIL, respectively. Five QTLs, qCL-6-2, qFIL-6-5, qSIL-6-2, qTIL-6-3, and qFOIL-7-5, explained the largest phenotypic variance of CL, FIL, SIL, TIL, and FOIL, respectively. RM1340, RM1374, RM281, RM233, and RM225 were stably and specifically associated with CL, FIL, SIL, TIL, and FOIL, respectively. Fortythree effective alleles were identified. Four and three donors with negative and positive alleles were recommended. There was a highly significant phenotypic difference between accessions with or without effective alleles. These QTLs, associated markers, effective alleles, and their donors could be used to improve CL and specific EIL in japonica rice. [ABSTRACT FROM AUTHOR]

Plant height (PH) has strong genetic associations with plant height components (PHC), such as spike length (SL), the first (FIL), second (SIL), third (TIL) and fourth internode length (FOIL) from the top. To dissect the genetic relationships between PH and individual PHC, both unconditional (UAM) and conditional association mapping (CAM) were conducted by phenotyping 278 japonica rice (Oryza sativa L. subsp. japonica) accessions with 154 polymorphic SSR markers in 2010 and 2011. A total of 26 significant marker-trait associations (MTAs) (P < 0.001) for PH were identified by using UAM within 19 markers in both years. Seven of the 19 markers were associated with PH in both 2010 and 2011. By using CAM, additional 35 significant MTAs (P < 0.001) were identified within 27 markers in 2 yr, when the influences of SL, FIL, SIL, TIL and FOIL were excluded. Four of the 27 markers were suppressed by different components in both years. CAM indicated that TIL contributed the most to PH, followed by SL, FOIL, SIL, and FIL. Any associated marker for PH identified by UAM and CAM was associated with at least one of the five PHC traits and explained 2.76 ~ 15.20% of the phenotypic variation. The CAM could be used to evaluate genetic relationships between PH and PHC, and efficiently and precisely reveal counteracting associated markers. This study will provide theoretical bases for the improvement of PH in rice breeding programs. [ABSTRACT FROM AUTHOR]

In this study, single and double-labeling immunofluorescence histochemistry, Western blot and real-time polymerase chain reaction were used to study the expression of P2Y receptors in developing mouse skeletal muscle and during injury and repair. The results show that P2Y receptor immunoreactive (ir) cells were first detected in the dermamyotome at embryonic (E) day 9. The number and immunostaining intensity of the P2Y receptor-ir cells increased from E9 to E13, but decreased from E15 to postnatal day 60 in the developing skeletal muscle system. The expression levels of P2Y receptor protein and mRNA increased rapidly from 1 to 5 days after skeletal muscle injury and then decreased almost to the control level from 7 to 10 days, at the beginning of regeneration. P2Y receptor-immunoreactivity was mainly localized to the ends of single myoblasts and myotube processes in the developing and injury-repair skeletal muscle tissues. These data suggest that the P2Y receptor may be involved in the development and regeneration of skeletal muscle, especially in the migration and extension of the myoblast and myotube in developing and regenerating skeletal muscle. [ABSTRACT FROM AUTHOR]

Objectives/Hypothesis: To evaluate the effects of long-term denervation on satellite cells (SCs) as myogenic stem cells in human posterior cricoarytenoid (PCA) muscle. Study Design: Histological investigation of SCs and quantitative assessment of myoD and myogenin, which are two key myogenic regulatory factors. Methods: According to the course of denervation, denervated PCA muscles of 58 patients who suffered from traumatic unilateral vocal cord paralysis were divided into four groups: group A (6-12 months, 15 cases), group B (13-24 months, 17 cases), group C (25-36 months, 14 cases), and group D (more than 36 months, 12 cases). Normal PCA muscles (12 cases) were used as a control group. Immunofluorescence labeling was used to visualize the SCs. Transcription and protein expression levels of myoD and myogenin were assessed using real-time quantitative polymerase chain reaction and Western blots, respectively. Results: MyoD- and myogenin-positive cells and embryonic myosin heavy chain-positive myofibers were detected in group A and most of the samples of group B. Transcription levels of myoD and myogenin were highly upregulated in groups A and B, whereas groups C and D showed no significant difference as compared to control. Protein expression levels of myoD and myogenin peaked in group A, which was significantly different than group B. In contrast, no expression was observed in the other groups. Conclusions: Activated SCs contribute to regenerative myogenesis in denervated laryngeal muscles through compensatory mechanisms. Laryngeal muscles exhibit persistent regenerative potential from the viewpoint of muscle SCs after less than 2 years of denervation. Laryngoscope, 2010 [ABSTRACT FROM AUTHOR]