Search

A population of chromosome segment substitution lines was developed using KDML105 as the recurrent parent and one of DH212 (IR68586-F2-CA-143) or DH103 (IR68586-F2-CA-31) as the donor parent. The donor parents are part of a doubled haploid population from a cross between CT9993, an upland japonica accession, and IR62266, a lowland indica accession. Multiple QTL that are relevant to drought avoidance, drought tolerance and yield traits under drought stress were mapped in this doubled haploid population and the segments selected for the chromosome segment substitution lines were chosen to capture these QTL. The chromosome segment substitution line population was phenotyped under irrigated and mild drought stress conditions, which identified that many yield traits under drought stress had been introduced into the chromosome segment substitution lines.

Epistasis plays an important role in manipulating rice tiller number, but epistatic mechanism still remains a challenge. Here we showed the process of epistatic analysis between tillering QTLs. A half diallel mating scheme was conducted based on 6 single segment substitution lines and 9 dual segment pyramiding lines to allow the analysis of 4 epistatic components. Additive-additive, additive-dominance, dominance-additive, and dominance-dominance epistatic effects were estimated at 9 stages of development via unconditional QTL analysis simultaneously. Unconditional QTL effect (QTL cumulative effect before a certain stage) was then divided into several conditional QTL components (QTL net effect in a certain time interval). The results indicated that epistatic interaction was prevalent, all QTL pairs harboring epistasis and one QTL always interacting with other QTLs in various component ways. Epistatic effects were dynamic, occurring mostly within 14d and 21–35d after transplant and exhibited mainly negative effects. The genetic and developmental mechanism on several tillering QTLs was further realized and perhaps was useful for molecular pyramiding breeding and heterosis utilization for improving plant architecture.

Background: Dynamic regulations of QTLs still remain mysterious. Single segment substitution lines and conditional QTL mapping, functional QTL mappings are ideal materials and methods to explore epistatic interactions, expression patterns and functions of QTLs for complex traits.Results: Based on single segment substitution lines five QTLs on plant height in rice were identified first in this paper, and then their epistatic interactions, expression patterns and functions were systemmatically studied by tailing after each QTL. Unconditional QTL mapping showed the five QTLs were with significant effects at one or more stages, all of which increased plant height except QTL1. They interacted each other as homeostatic mechanisms to regulate plant height with negative effects before 72d after transplanting and positive since then. Conditional QTL mapping revealed the expression quantities and periods for the five QTLs and their epistases. Temporal expression pattern was verified again by selective expressions of QTLs in specific periods. QTL1 expressed negatively while QTL2 and QTL4 positively, mainly occurring in the periods from 35 to 42d and from 49 to 56d after transplanting. Epistatic expressions were dispersedly in various periods, mainly with negative effects before 35d while positive since then. Functional QTL mapping discovered the five QTLs brought the inflexion point ahead of schedule, accelerated the growth and the degradation, and changed the peak of plant height, while their interactions had the opposite effects approximately. This paper uncovered the dynamic rules of five QTLs and their interactions on plant height systematically, which will be helpful to understand the genetic mechanism for developmental traits.Conclusions: Five single segment substitution lines were tested with significant additive, dominant and epistatic effects of QTLs on plant height. Additive and dominant expressions were mainly in two periods, while epistasis dispersedly. The five QTLs and their interactions significantly regulated the developmental trajectory of plant height.

An elite backcrossed inbred line Z550 with increased grains per panicle was identified from advanced backcrosses between Nipponbare and Xihui 18 by simple sequence repeat (SSR) marker-assisted selection (MAS). Z550 carries 13 substitution segments distributed on chromosomes 1, 6, 7, 8, 9, 10, and 12, with an average substitution length of 1.68 Mb. Compared with the Nipponbare parental line, plant height, panicle length, spikelets per panicle, grains per panicle, and grain weight for Z550 were significantly increased. While the grain width of Z550 was significantly narrower, and the seed setting ratio (81.43%) was significantly lower than that of Nipponbare, it is still sufficient for breeding purposes. Quantitative trait loci (QTLs) mapping for important agronomic traits was conducted with the F2 population derived from Nipponbare crossed with Z550 using the restricted maximum likelihood (REML) method. A total of 16, including 12 previously unreported QTLs were detected, with contribution rates ranging from 1.46 to 10.49%. Grains per panicle was controlled by 8 QTLs, 5 of which increased number of grains whereas 3 decreased it. qGPP-1, with the largest contribution (10.49%), was estimated to increase grains per panicle by 30.67, while qGPP-9, with the minimum contribution rate (2.47%), had an effect of increasing grains per panicle by 15.79. These results will be useful for further development of single segment substitution lines with major QTLs, and for research of their molecular functions via QTL cloning.

Rice growth is sensitive to low temperature. Chilling injury is one of the main natural disasters in rice cultivation, and is damaging to rice growth at all developmental stages. Low-temperature germinability (LTG) is an important trait for seedling establishment, especially in rice direct-sowing practice. However, the genetic mechanism of LTG remains elusive. Here, we report the mapping of QTLs controlling LTG in rice using 586 single segment substitution lines (SSSL) derived from 4 AA-genome wild rice species. 21 SSSLs with the highest germination rate at low temperature in both of the two tested seasons were selected, from them 10 QTLs controlling LTG were identified by substitution mapping to locate on 6 chromosomes: chromosome 1, 3, 5, 7, 8 and 11, with an interval length of 3.45 to 20.15 cM. Five QTLs were detected from Niv-SSSls: qLTGn3-1, qLTGn5-1, qLTGn5-3, qLTGn7-1 and qLTGn7-2, their additive effects ranged from 3.72% to 19.74% in late season 2018. qLTGb1-1 and qLTGb8-2 were detected in the SSSLs with O. barthii as the donor and they accounted for at least 9.51% of the total phenotypic variation. Two QTLs, qLTGg5-2 and qLTGg8-1, were derived from O. glumaepatula, and their average additive effects were 4.28% and 20.39% in late seasons 2018, respectively. qLTGm11-1 on chromosome 11 was the only QTL identified from O. meridionalis. All QTLs derived from wild rice species improved low-temperature germination significantly. The SSSL library with wild rice species as donor is therefore a valuable resource for rice germplasm innovation and the breeding of chilling-resistant varieties.

Seed yield is one of the main limitations in hybrid rice production. The improvement of stigma exsertion rate (SER) of male sterility lines is essential for the higher seed yield in hybrid rice. Wild rice species are valuable germplasms with exserted stigma. It is worthy of mining-related genes for SER in wild rice species, as well as probing the way to use the beneficial genes in rice breeding. In the present study, we identified a total number of 36 stable QTLs for the SER distributing on 11 chromosomes by using a set of single-segment substitution lines (SSSLs) of 3 AA-genome wild rice species, O. barthii, O. meridionalis, and O. rufipogon. The mean genetic effects of these QTLs were ranged from 14.50 to 41.25% during 2016–2017. Twelve QTLs among them were novel by comparing the chromosome intervals with the reported QTLs. Besides, 7 homozygous 2-QTL pyramiding lines (PLs) were developed in BAR-SSSLs and MER-SSSLs to detect QTL interactions on the same background of HJX74. The epistatic effects in 3 out of 7 QTL pairs were positive, including qSERb3-1/qSERb6-1, qSERb3-1/qSERb8-1, and qSERb3-1/qSERb12-1, which mean epistatic effect was 13.56%, 4.76%, and 7.29% in 2018–2019, respectively. The PL of B6/B19 (qSERb3-1/qSERb12-1) had the highest mean SER of 80.59% and the largest pyramiding effect of 55.51%. The results in the present study demonstrated that SSSLs were the elite materials for SER QTL detection from wild rice species, and elite PLs could be developed among SSSLs for SER improvement in hybrid rice breeding.

Background: Adjacent segment degeneration (ASD) is a major issue after posterior lumbar interbody fusion (PLIF). Several studies have reported the potential causes of ASD based on radiography. However, the postoperative dynamic changes in the adjacent segments are not clear. This study aimed to determine the effect of PLIF on ASD using a formetric 4D system and to compare the effectiveness of this system with that of traditional radiography for the prediction of ASD. Methods: Eighty-five consecutive patients who underwent PLIF of a single-segmen t were included. The formetric 4Dsystem was used to calculate the relative rotation angle between the fusion segment and the upper and lower adjacent vertebrae preoperatively and at 6, 12 and 24 months postoperatively. The range of motion (ROM) and disc height (DH) of the adjacent segments were measured using radiography preoperatively and at 24 months postoperatively. At the final follow-up, the visual analogue scale (VAS) and Oswestry disability index (ODI) were used to evaluate the surgical outcome. The patients were divided into two groups according to the occurrence of radiographic ASD: the ASD group with progression of degeneration and the N-ASD group without progression of degeneration. The clinical outcomes and measurement data between the two groups were compared and analyzed. Results: The index fusion segments included L2-3 to L5-S1. Preoperatively, the relative rotation angles between the fused segment and the upper and lower adjacent vertebrae were 5.1°±2.2°and 3.3°±2.0°,respectively, and both angles increased significantly at all time-points after surgery ( p 0.05), while the relative rotation angle with the upper adjacent vertebra was greater in the ASD group than in the N-ASD group ( p

The ability to reproducibly target expression of transgenes to small, defined subsets of cells is a key experimental tool for understanding many biological processes. The Drosophila nervous system contains thousands of distinct cell types and it has generally not been possible to limit expression to one or a few cell types when using a single segment of genomic DNA as an enhancer to drive expression. Intersectional methods, in which expression of the transgene only occurs where two different enhancers overlap in their expression patterns, can be used to achieve the desired specificity. This report describes a set of over 2800 transgenic lines for use with the split-GAL4 intersectional method.

Greatly increased yield by utilizing of heterosis has been a great success in rice over the past 40 years. The cytoplasmic male sterility (CMS) line is a key line of hybrid rice. However, the CMS line was very difficult to develop following the traditional breeding methods. Here, we report an example to develop and improve CMS lines sustainably by using the strategy of breeding by design under the platform of single segment substitution line (SSSL) library in the Huajingxian74 (HJX74) genetic background. The CMS lines HZA and HBA with the wild abortive (WA) cytoplasm from Zhenshan97A and BobaiA, respectively, were firstly developed in the HJX74 background through marker-assisted selection. Then, four isonuclear alloplasmic CMS lines with the WA, dwarf wild abortive (DA), and Yegong abortive (YA) types of CMS cytoplasm, respectively, were developed by using the HZB maintainer line. According to the goal of design, E5-HXA and E5-HBA were developed by pyramiding five target genes, Wxg1, ALK, fgr, gs3, and OsMADS50, located on the chromosomal substituted segments in four SSSLs. The two CMS lines show the phenotypes of earlier in heading date, longer and narrower in grain shape, lower in amylose content, and fragrant smell. Thus, the goal of design was achieved on the platform of SSSL library. Compared with that in the E5-HXA line carrying the rf3 and rf4 genes of XieqingzaoA, the CMS in the E5-HBA line with the rf3 and rf4 genes from BobaiA was susceptible to environmental impact and easy to be restored. Therefore, the balance between sterility and its restored ability in CMS lines should be concerned in breeding by design.

Heat shock proteins of 70 kDa (Hsp70s) are ubiquitous and highly conserved molecular chaperones. They play multiple essential roles in assisting with protein folding and maintaining protein homeostasis. Their chaperone activity has been proposed to require several rounds of binding to and release of polypeptide substrates at the substrate-binding domain (SBD) of Hsp70s. All available structures have revealed a single substrate-binding site in the SBD that binds a single segment of an extended polypeptide of 3–4 residues. However, this well-established single peptide-binding site alone has made it difficult to explain the efficient chaperone activity of Hsp70s. In this study, using purified proteins and site-directed mutagenesis, along with fluorescence polarization and luciferase-refolding assays, we report the unexpected discovery of a second peptide-binding site in Hsp70s. More importantly, the biochemical analyses suggested that this novel binding site, named here P2, is essential for Hsp70 chaperone activity. Furthermore, cross-linking and mutagenesis studies indicated that this second binding site is in the SBD adjacent to the first binding site. Taken together, our results suggest that these two essential binding sites of Hsp70s cooperate in protein folding.

Additive effects (A) and additive-by-environment interactions (A×E) for five rice yield components were analysed using 20 SSSLs under mixed linear model methodology. Thirty-one QTLs were detected. Different yield components have different QTL-by-environment (Q×E) interaction patterns. No A×E interaction effects were detected for the four QTLs for panicle number (PN). Four QTLs detected for spikelets per panicle (SPP) had A×E interactions. Five of seven QTLs detected for grains per panicle (GPP), two of 10 QTLs detected for 1000-grains weight (GWT) and three of six QTLs detected for seed set ratio (SSR) showed significant A×E interaction. Most of these QTLs were distributed in clusters across the genome. The complexity of linkage and pleiotropy of these QTLs plus environmental effect may result in the diversity of the yield phenotype in the SSSLs. Only S19 exhibited a significant increase in yield with a predicted gain by 281.58 kg ha−1. The results may be useful to design a better breeding strategy that takes advantage of QTL-by-environment interaction effects in each of the SSSLs.

The present study aimed to dissect the genetic basis of heterosis for grain yield and its components in maize (Zea mays L.). Quantitative trait loci (QTL) and heterotic loci (HL) were analyzed using a set of 203 single segment substitution lines (SSSLs) and its testcross population in three environments. Forty-one QTL were identified as responsible for grain yield, ear length, ear diameter, row number, kernel number per row, and 100-kernel weight in the SSSLs population, and 17 QTL were conserved across the three environments. In the heterosis analysis, 36 HL were identified for grain yield and five yield-related traits in the test population in the three environments. Among the HL, only six (16.7 %) for ear length, kernel number per row, 100-kernel weight, and grain yield were consistent with the results of QTL mapping. In addition, 16.7 % of the heterotic loci showed a dominant effect and 83.3 % showed an over-dominant effect. The results implied that dominance and over-dominance were two important components of heterosis in maize grain yield and yield-related traits in the present testcross population.

Since 2007, Ulva macroalgal blooms have occurred along the coastal areas of the Yellow Sea, China. These blooms are dominated by fragments of Ulva prolifera in the early stages of development. The objectives of this study were to identify the primary mode of asexual reproduction for U. prolifera and to evaluate the contribution of these thalli fragments to the formation of blooms. Four different growth and reproductive strategies of U. prolifera segments were found including: 1) tubular diameter becoming larger; 2) formation of new branches; 3) release of zoids; and 4) polarized growth. This is the first report showing the development of numerous blade-lets from a single segment, which is remarkably different from previous studies on other Ulva species. The results in the present study provide critical information to understand how this species is able to support its explosive growth during a bloom.

Fibre strength (FS) is an important quality attribute in the modern textile industry, which is genetically controlled by quantitative trait loci (QTLs). Fine-mapping stable QTLs for FS to identify candidate genes would be valuable for uncovering the genetic basis of fibre quality traits in cotton. Here, a single segment introgression line, IL-D2−2, from the cross of (TM-1×TX-1046) reported in our previous studies, was found to have significantly improved FS compared with the recurrent parent TM-1. To fine-map the QTLs of the FS, we further crossed IL-D2−2 with its recurrent parent TM-1 to produce F2 and F2:3 populations. QTL analysis and substitution mapping showed qFS-Chr. D02 was anchored into a 550.66 kb-interval between two markers, INTR1027 and JESPR-231. This interval contained 67 genes, among which 27 genes related to cell-wall synthesis were selected to conduct qRT-PCR. The results revealed seven genes were expressed significantly differently during the fibre secondary-wall-thickening stage (10–25 days post-anthesis), three being upregulated and four downregulated in IL-D2−2. Both GH_D02G2269 (UDP-glucosyl transferase 84B1) and GH_D02G2289 (unknown function (DUF869)) with nonsynonymous SNPs in IL-D2−2 had significantly downregulated expression, suggesting they were candidates for qFS-Chr. D02. This research provides information about marker-assisted selection for cotton fibre strength improvement.

Single segment substitution lines (SSSLs) have been confirmed to be powerful tools to perform quantitative trait locus (QTL) analysis. This study illuminated the process and methods of QTL analysis with SSSLs on heading date (HD) in rice. QTL identification under two cropping seasons revealed 98 of 202 SSSLs associated with HD. A total of 22 QTLs were positioned in relative narrow regions on chromosomes by mrMLM.GUI software. QTL qHd3-1 was precisely positioned at 4.4 cM on chromosome 3 by a secondary F2 population. Through SSSL pyramiding, double segment substitution lines were constructed and used to analyze epistatic interactions of digenic loci. Epistatic effects for three pairs of QTLs were estimated, indicating the interactions of QTL qHd3-1 with other QTLs detected and the role to enhance the expression of early ripening or restraining of late flowering QTLs. Additionally, analysis of QTL in different environments provided information about the stability of HD QTLs. This type of research points out the way to excavate favorable genes for design breeding.

We performed whole-genome sequencing for eight inbred rat strains commonly used in genetic mapping studies. They are the founders of the NIH heterogeneous stock (HS) outbred colony. We provide their sequences and variant calls to the rat genomics community. When analyzing the variant calls we identified regions with unusually high levels of heterozygosity. These regions are consistent across the eight inbred strains, including Brown Norway, which is the basis of the rat reference genome. These regions show higher read depths than other regions in the genome and contain higher rates of apparent tri-allelic variant sites. The evidence suggests that these regions may correspond to duplicated segments that were incorrectly overlaid as a single segment in the reference genome. We provide masks for these regions of suspected mis-assembly as a resource for the community to flag potentially false interpretations of mapping or functional results.

Heading date directly determines the planting districts and seasons, and thus plays an important role for producing and introducing of varieties. Limited to the materials and methodologies, analysis of epistasis still presents an obvious challenge. This thesis estimated effectively four types of epistatic components among dual QTLs on heading date based on eight single segment substitution lines (SSSLs) in rice. The results confirmed that they carried truly with heading date QTLs. Eleven pairs of QTLs were with 50.0% of significant epistatic effects, of which additive-additive, additive-dominance or dominance-additive, and dominance-dominance interaction components occupied 40.9%, 50.0% and 59.1%, respectively. One QTL always interacted with multiple QTLs in various components. Several characteristics of epistasis on heading date were found that 1) different epistatic components had almost consistent directions; 2) dominance-dominance epistasis was perhaps most important in the four epistatic components; 3) epistasis was mostly positive, delaying rice heading; and 4) all epistatic components were seasonal sensitive. Two flowering pathways were further confirmed via a network constructed among these QTLs. These results have further confirmed the prevalence of epistatic interactions, deepened the understanding of genetic and flowering mechanism, and excavated several advantageous genes on heading date in rice.

Exploitation of the heterosis of hybrid rice has shown great success in the improvement of rice yields. However, few genotypes exhibit strong restoration ability as effective restorers of cytoplasmic male sterility (CMS) in the development of hybrid rice. In this study, we developed a platform for the breeding by design of CMS restorer lines based on a library of chromosomal single segment substitution lines (SSSLs) in the Huajingxian74 (HJX74) genetic background. The target genes for breeding by design, Rf34 and Rf44, which are associated with a strong restoration ability, and gs3, gw8, Wxg1 and Alk, which are associated with good grain quality, were selected from the HJX74 SSSL library. Through pyramiding of the target genes, a restorer line, H121R, was developed. The H121R line was then improved regarding blast resistance by pyramiding of the qBLAST11 gene. Hence, a new restorer line with blast resistance, H131R, was developed. The platform involving the Rf34 and Rf44 restorer genes would be used for the continuous improvement of restorer lines through breeding by design in rice.

Hua-jing-xian 74 and its 12 single segment substitution lines (SSSLs) in rice were used as crossing parents to construct a half diallel crossing population. A total number of 91 materials were grown under three planting densities. By analysis of average plant height (PH) over all environments 10 SSSLs were detected with significant additives and 6 SSSLs with significant dominances. These SSSLs were further tested under different densities respectively, indicating that some of single locus effects were sensitive to densities and the conditions under the density of 16.7 cm × 16.7 cm maybe inhibited the expressing of these PH QTLs. Qualitative and quantitative analyses of each four participating genotypes indicated that digenic interactions among these QTLs were prevalent. Of 66 tested interactions, about 42.4% were epistatic (P < 5%). Although some QTLs hadn’t single locus effects, they were possible to form digenic interactions. A significant finding was that the detected epistases were mostly negative. Additionally, these epistases were also found being sensitive to planting densities, the conditions under the density of 10 cm × 16.7 cm perhaps promoted the expressing of epistatic interactions among PH QTLs.

The ability to reproducibly target expression of transgenes to small, defined subsets of cells is a key experimental tool for understanding many biological processes. The Drosophila nervous system contains thousands of distinct cell types and it has generally not been possible to limit expression to one or a few cell types when using a single segment of genomic DNA as an enhancer to drive expression. Intersectional methods, in which expression of the transgene only occurs where two different enhancers overlap in their expression patterns, can be used to achieve the desired specificity. This report describes a set of over 2,800 transgenic lines for use with the split-GAL4 intersectional method.

The elite indica rice variety Hua-jing-xian 74 and its 12 single segment substitution lines (SSSLs), all of which have been shown to have quantitative trait loci (QTL) for panicle number (PN), were used as crossing parents to construct a half-diallel crossing population with the aim of analyzing the expression of these QTL under different cropping densities. A total of 91 half-diallel crossing combinations were grown in two planting seasons at three cropping densities. PN was measured at the mature stage. The additive, dominant and epistatic effects of the 12 QTL as well as their interaction effects with the seasons and with the densities were estimated based on genetic effect components. Our analysis revealed that PN generally decreased with increasing cropping density. In the six single environments, eight additive QTL, nine dominant QTL and 49 pairs of epistatic QTL were detected, which were mostly associated with estimated positive, positive and negative effects, respectively. Expression of these QTL differed across planting seasons and cropping densities, implying an existing of QTL-by-environment interaction. Further analysis of the QTL effect components revealed that seven, eight and 28 pairs of QTL were present with significant additive, dominance, epistasis and/or interaction effects with densities. QTL additive and dominant effects were mostly positive, while epistatic effects were all negative. No significant QTL-by-season effects were detected. QTL Pn3-1, without any significant additive-by-density interaction effect, showed stable additive expression across densities. QTL Pn3-1, Pn3-2 and Pn6-1 showed stable dominance expression, and QTL pairs Pn2-1/Pn9, Pn2-2/Pn3-1, Pn2-2/Pn6-2, Pn3-1/Pn6-1, Pn3-1/Pn7 and Pn6-1/Pn6-3 had stable epistasis expression. The remaining significant QTL had different effects across densities. We determined that a density of 10 × 16.7 cm2 had little influence on QTL expression, that a density of 16.7 × 16.7 cm2 mostly increased QTL additive and dominant effects and decreased QTL epistatic effects and that a density of 23.3 × 16.7 cm2 had the opposite impact on QTL effects compared with 16.7 × 16.7 cm2. Additionally, the influence of density on QTL epistatic effect was generally larger than that on QTL additive or dominant effect. These results provide the information on cropping density and how it influences PN QTL expression, which may be useful information to improve rice PN via heterosis and/or QTL pyramiding.

Cold stress is one of the main constraints in rice production, and damage from cold can occur at different developmental stages in rice. Understanding the genetic basis of cold tolerance is the key for breeding cold-tolerant variety. In this study, we used single segment substitution lines (SSSLs) derived from a cross between cold-tolerant japonica variety “Nan-yang-zhan” and a popular indica variety “Hua-jing-xian 74” to detect and pyramid QTLs for cold tolerance at the bud bursting and the seedling stages. Evaluation of cold tolerance of these SSSLs and their recurrent parent helped identify two cold-tolerant QTLs (qCTBB-5 and qCTBB-6) at the bud bursting stage and two cold-tolerant QTLs (qCTS-6 and qCTS-12) at the seedling stage. The SSSLs carrying these QTLs showed stronger cold tolerance than their recurrent parent HJX74 did in three independent experiments. The qCTBB-6 and qCTS-6 were mapped to the same chromosomal region. QTL pyramiding was performed by intercrossing of SSSLs carrying the respective QTLs for cold tolerance at the bud bursting stage and the seedling stage and marker-assisted selection (MAS). The selected pyramiding line SC1-1 with different cold-tolerant QTLs showed cumulative effects on cold tolerance. Our results suggest that different genes (QTLs) control cold tolerance at bud bursting and seedling stages, and pyramiding of stable expression QTLs for cold tolerance at different developmental stages through MAS is a good strategy to prevent cold damage in rice.

Twelve single segment substitution lines (SSSLs) in rice, which contain quantitative trait loci (QTLs) for tiller number detected previously, were used to study dynamic expression of the QTLs in this study. These SSSLs and their recipient, Hua-Jing-Xian 74 (HJX74), were used to produce 78 crossing combinations first, and then these combinations and their parents were grown in two planting seasons with three cropping densities. Tiller number was measured at seven developmental stages. QTL effects including main effects (additive, dominance and epistasis), QTL × season and QTL × density interaction effects were analyzed at each measured stage. The additive, dominant and epistatic effects of the 12 QTLs as well as their interaction effects with the seasons and with the densities all display dynamic changes with the development. Eight QTLs are detected with significant additive effects and/or additive × season and/or additive × density interaction effects at least at one developmental stage, and all QTLs have significant dominant and epistatic effects and/or interaction effects involved in. For most of the QTLs dominant effects are much bigger than additive effects, showing overdominance. Each QTL interacts at least with eight other QTLs. Additive and dominant effects of these QTLs are mostly positive while epistatic effects are negative and minor. Most of the QTLs show significant interactions with planting seasons and cropping densities, but the additive effects of QTLs Tn3-1 and Tn3-2, the dominant effects of QTL Tn7 and Tn8, and the epistatic effects of 14 pairs of QTLs are stable across seasons and the dominant effect of QTL Tn3-3 and the epistatic effects of QTL pairs Tn2-1/Tn6-2, Tn2-1/Tn9 and Tn3-3/Tn6-3 are nearly consistent across cropping densities. This paper is the first report of dynamics on dominances and epistasis of QTLs for tiller number in rice and provides abundant information, which is useful to improve rice tiller number via heterosis and/or QTL pyramiding.

Rice grain shape is one of the important factors affecting grain quality and yield, but it is liable to be influenced by genetic backgrounds and environments. The chromosome single segment substitution lines (SSSLs) in rice have been considered as ideal populations to identify the quantitative trait loci (QTLs). In this study, 22 QTLs affecting rice grain shape were detected to be distributed on eight chromosomes except chromosomes 6, 9, 11 and 12 by using SSSLs. Among them, seven QTLs conditioned grain length, six conditioned grain width, five affected grain length-width ratio and four controlled grain thickness.

In the males of species of Aulacophora Chevrolat (Coleoptera: Chrysomelidae) antennae are sometimes morphologically different. Relationships between such modified antennae and the aedeagus is studied and discussed. It has been observed that males with antennae showing variations in segments 3, 4 and 5 only, and those with long hairs possess a small aedeagus; and those with more than three segments or only single segment of antennae modified have a larger aedeagus. Presumably in those males with variations in segments 3, 4 and 5 only, and those with long hairs, these aid as a clasping organ.

A library consisting of 1123 single segment substitution lines (SSSLs) in the same genetic back-ground of an elite rice variety Huajingxian74 (HJX74) was evaluated for heading date. From this library, two SSSLs, W23-03-8-9-1 and W15-03-1-31, with substitution segments on chromosome 3 and 2, respectively, were found to have significantly different heading date from the recipient HJX74. For genetic dissection and epistatic interaction of quantitative trait loci (QTLs) for heading date in two SSSLs, three secondary SSSLs with smaller substitution segments and genic pyramiding lines (GPLs) were developed from an F2 segregating population of a cross between the two donor SSSLs, W23-03-8-9-1 and W15-03-1-31, using marker-assisted selection (MAS). The QTL analysis revealed that QTL for heading date detected in SSSL W23-03-08-9-1 was genetically dissected into two QTLs, qHD3-1 and qHD3-2, by overlapping mapping. At the same time, one QTL, qHD2-1 in the donor SSSL W15-03-1-31 was also identified. Analysis of GPLs for heading date showed epistatic interactions between qHD3-1 and qHD3-2, between qHD3-1 and qHD2-1, and between qHD3-2 and qHD2-1. These QTLs and epistatic interactions were confirmed in three cropping seasons under different natural daylength conditions, and their physiological functions for heading date were performed.

To detect quantitative trait loci (QTLs) for plant height and its components in rice (Oryza sativa L.) as well as their gene action, 16 secondary single segment substitution lines (SSSLs) and 15 double segment pyramiding lines (DSPLs) with Huajingxian 74 background were used as mapping populations. A total of 11 QTLs were identified on chromosomes 4, 6, and 10, containing 3 for plant height, 1 for the first internode from the top, 2 for length of the second internode from the top, 2 for length of the third internode from the top, and 3 for length of the fourth internode from the top. Furthermore, 23 pairs of digenic interactions were detected for plant height and the other 5 traits. Among them, 7 interactions occurred between 2 loci without obvious effects on the traits, and 16 interactions each involving 1 locus with and another without main effect at the single-locus level. The results suggest that both additive effect of QTL and epistasis effect between QTLs play important roles in the heritance of plant height and its components. Secondary SSSLs and DSPLs derived from crosses of primary SSSLs are favorable in improving efficiencies of QTL identification and epistasis effect analysis.

Single segment substitution lines (SSSLs) each with a single chromosome segment from a donor under the same genetic background as the recipient were developed in rice by advanced backcrossing and molecular marker-assisted selection. Using the SSSLs, the QTLs for the important agronomic traits in rice would be detected under different environmental conditions. Detection of the QTLs controlling 22 important traits in rice was done with 32 SSSLs by the randomized block design in 2–4 cropping seasons. 59 QTLs were detected and distributed on chromosomes 1, 2, 3, 4, 6, 7, 8, 10, and 11, of which 18 QTLs were detected more than twice. Only 30.5% of the QTLs were detected repeatedly in different cropping seasons. Most of the QTLs of important agronomic traits were of little additive effects and instability. The QTLs controlling the traits, such as grain weight, grain length, ratio of grain length to width, and heading date were relatively stable. The stable QTLs usually had larger additive effects and were less affected by environment. The QTLs for the important agronomic traits were detected using the SSSLs in rice with high resolution under different environmental conditions. The instability of the QTLs may be the basis of the variation of rice plants during growth and development. It would be the genetic basis for improving yield and quality in rice cultivars by farming methods.

The number of leg-bearing segments in centipedes varies extensively, between 15 and 191, and yet it is always odd [1, 2]. This suggests that segment generation in centipedes involves a stage with double segment periodicity and that evolutionary variation in segment number reflects the generation of these double segmental units. However, previous studies have revealed no trace of this [3–5]. Here we report the expression of two genes, an odd-skipped related gene ( odr1 ) and a caudal homolog, that serve as markers for early steps of segment formation in the geophilomorph centipede, Strigamia maritima . Dynamic expression of odr1 around the proctodaeum resolves into a series of concentric rings, revealing a pattern of double segment periodicity in overtly unsegmented tissue. Initially, the expression of the caudal homolog mirrors this double segment periodicity, but shortly before engrailed expression and overt segmentation, the intercalation of additional stripes generates a repeat with single segment periodicity. Our results provide the first clues about the causality of the unique and fascinating "all-odd" pattern of variation in centipede segment numbers and have implications for the evolution of the mechanisms of arthropod segmentation.

To assess the potential of intrinsically disordered proteins (IDPs) as drug design targets, we have analyzed the ligand-binding cavities of two datasets of IDPs (containing 37 and 16 entries, respectively) and compared their properties with those of conventional ordered (folded) proteins. IDPs were predicted to possess more binding cavity than ordered proteins at similar length, supporting the proposed advantage of IDPs economizing genome and protein resources. The cavity number has a wide distribution within each conformation ensemble for IDPs. The geometries of the cavities of IDPs differ from the cavities of ordered proteins, for example, the cavities of IDPs have larger surface areas and volumes, and are more likely to be composed of a single segment. The druggability of the cavities was examined, and the average druggable probability is estimated to be 9% for IDPs, which is almost twice that for ordered proteins (5%). Some IDPs with druggable cavities that are associated with diseases are listed. The optimism versus obstacles for drug design for IDPs is also briefly discussed.

Rheoptilum gen. n. is established for R. arni sp. n. and R. lokohensis sp. n. from Madagascar. Imaginal and larval stages are both described. Rheoptilum nymphs have two important adaptations: mouthparts are highly modified for scraping and the habitus is adapted for fast flowing waters. The genus possesses an extremely broad labrum with distal margin almost straight, incisors almost fused, right prostheca long and slender, caudal filament reduced to a single segment, legs long and slender, dorsally bordered with long and thin setae and the body dorsoventrally flattened. This combination of features distinguishes Rheoptilum from other Afro-Malagasy baetid genera. The phylogenetic position of this new genus is discussed.

Molecular dynamics (MD) simulations are performed to investigate the adsorption mechanics and conformational dynamics of single and multiple bovine serum albumin (BSA) peptide segments on single-layer graphene through analysis of parameters such as the root-mean-square displacements, number of hydrogen bonds, helical content, interaction energies, and motions of mass center of the peptides. It is found that for the single segment system, destabilization of the helical structures in the form of the reduction in hydrogen bond numbers and [Formula: see text]-helical content of the peptides occurred due to the strong interactions between BSA peptides and graphene. Similar destabilizations of the individual segments in the multi-segment system can occur as well, albeit with greater complexity and in a lesser degree due to the inter-segment interactions. Alleviation of decreases in the total helical content in the multi-segment system indicates protective capabilities of segment–segment interactions, which weaken their interactions with graphene. Diffusive motion upon adsorption of the segment(s) onto graphene is found to be highly confined, and the distance traversed by each segment in the multi-segment system was more significant than that in the single segment system, similarly attributable to reductions in their interactions with graphene due to inter-segment interactions.

The complete exoskeleton of the widely dispersed remopleuridid trilobite Hypodicranotus is reconstructed for the first time based on well-preserved silicified material of Hypodicranotus striatulus (Walcott 1875) from the lower Whittaker Formation (Upper Ordovician, Edenian) of the southern Mackenzie Mountains. The minute oval pygidium consists of a single segment and, as such, it is the most reduced trilobite pygidium known. The subfamily Hypodicranotinae Přibyl and Vaněk is a junior synonym of the Remopleuridinae Hawle and Corda.

Naturally occurring allelic variations underlying complex traits are useful resources for the functional analysis of plant genes. To facilitate the genetic analysis of complex traits and the use of marker-assisted breeding in rice, we developed a wide population consisting of 217 chromosome single-segment substitution lines (SSSLs) using Oryza sativa L. 'Hua-Jing-Xian74' (HJX74), an elite Indica cultivar, as recipient, and 6 other accessions, including 2 Indica and 4 Japonica, as donors. Each SSSL contains a single substituted chromosome segment derived from 1 of the 6 donors in the genetic background of HJX74. The total size of the substituted segments in the SSSL population was 4695.0 cM, which was 3.1 times that of rice genome. To evaluate the potential application of these SSSLs for quantitative trait loci detection, phenotypic variations of the quantitative traits of days to heading and grain length in the population consisting of 210 SSSLs were observed under natural environmental conditions. The results demonstrated that there was a wide range of phenotypic variation in the traits in the SSSL population. These genetic materials will be powerful tools to dissect complex traits into a set of monogenic loci and to assign phenotypic values to different alleles at the locus of interest.Key words: rice, mapping population, single segment substitution lines, marker-assisted selection, quantitative trait loci.

Axons in the bilateral brain of Drosophila decide whether or not to cross the midline before following their specific subsequent pathways. In commissureless mutants, the RP3 and V motoneuron axons often fail to cross the midline but subsequently follow the mirror-image pathways and innervate corresponding muscle targets on the ipsilateral side. Conversely, in roundabout mutants, the RP2 and aCC motoneuron axons sometimes cross the midline abnormally but their subsequent pathways and synaptic targeting are the perfect mirror images of those seen in wild type. Furthermore, within a single segment of these mutants, bilateral pairs of motoneuron axons can make their midline decisions independently of each other. Thus, neither the growth cones’ particular molecular experience nor the decision at the midline caused by these mutations affects their ability to respond normally to subsequently presented cues.

Submitted by Guilherme Lemeszenski (guilherme@nead.unesp.br) on 2013-08-22T18:57:52Z No. of bitstreams: 1 S0034-71082000000100015.pdf: 150929 bytes, checksum: 8a94d0e9cec5d1c6d4c6b801ad22cdca (MD5) Made available in DSpace on 2013-08-22T18:57:52Z (GMT). No. of bitstreams: 1 S0034-71082000000100015.pdf: 150929 bytes, checksum: 8a94d0e9cec5d1c6d4c6b801ad22cdca (MD5) Previous issue date: 2000-02-01 Made available in DSpace on 2013-09-30T19:52:58Z (GMT). No. of bitstreams: 2 S0034-71082000000100015.pdf: 150929 bytes, checksum: 8a94d0e9cec5d1c6d4c6b801ad22cdca (MD5) S0034-71082000000100015.pdf.txt: 17363 bytes, checksum: 3bde77135ba48d58ba7830e984e9d258 (MD5) Previous issue date: 2000-02-01 Submitted by Vitor Silverio Rodrigues (vitorsrodrigues@reitoria.unesp.br) on 2014-05-20T15:13:46Z No. of bitstreams: 2 S0034-71082000000100015.pdf: 150929 bytes, checksum: 8a94d0e9cec5d1c6d4c6b801ad22cdca (MD5) S0034-71082000000100015.pdf.txt: 17363 bytes, checksum: 3bde77135ba48d58ba7830e984e9d258 (MD5) Made available in DSpace on 2014-05-20T15:13:46Z (GMT). No. of bitstreams: 2 S0034-71082000000100015.pdf: 150929 bytes, checksum: 8a94d0e9cec5d1c6d4c6b801ad22cdca (MD5) S0034-71082000000100015.pdf.txt: 17363 bytes, checksum: 3bde77135ba48d58ba7830e984e9d258 (MD5) Previous issue date: 2000-02-01 Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) Antenas com malformações diversas, extraídas de zangões de Apis mellifera de ocelos claros, foram desenhadas e dissecadas para a contagem de discos olfativos dos segmentos morfologicamente alterados, em comparação com as antenas normais de seus irmãos. Alguns zangões apresentaram anormalidades morfológicas em um dos segmentos da antena direita ou esquerda, mas outros possuíam dois ou mais segmentos alterados na mesma antena. Zangões com malformações em ambas as antenas também foram observados. Os segmentos 4 e 5 do flagelo foram os mais freqüentemente afetados. em um menor número de casos, a freqüência de discos olfativos nos segmentos malformados não diferiu significativamente em relação à observada nos segmentos normais. Contudo, na maioria dos casos estudados, as malformações antenais ocasionaram uma significativa redução no número de discos olfativos dos segmentos malformados. Malformed antennae of Apis mellifera light ocelli drones were drawn, dissected and mounted permanently on slides containing Canada balsam, in order to count the olfactory discs present in each segment, in comparison with the number of those structures in normal antennae of their brothers. Some drones presented morphological abnormalities in a single segment of the right or left antenna, but others had two or more malformed segments in a same antenna. Drones with malformations in both antennae were also observed. The 4th and 5th flagellum segments were the most frequently affected. In a low number of cases the frequency of olfactory discs in malformed segments did not differ from that one recorded for normal segments. However, in most cases studied, the antennal malformations brought about a significant reduction in the number of olfactory discs from malformed segments. Universidade Estadual Paulista IBRC Departamento de Biologia Universidade Estadual Paulista IBRC Departamento de Biologia

In this study, six Secondary Single-segment substitution lines (SSSLs) and five double-segment substitution lines (DSSLS) that had higher yield were produced by selective crossing of seven primary SSSLs. The DSSL-D3 had significantly higher (by 9.44%) yield than Huajingxian74, the recurrent parent. With pyramided QTL qGL3, qGWT3, qPN and the Waxy locus, the DSSL D2 showed a higher yield (by 8.70%) combined with long and high-quality grain. These results indicated that pyramiding of favourable QTL using SSSLs is feasible to improve rice yield and quality.

Grain shape is one of the important factors determining rice yield and grain quality,it is a typical quantitative trait controlled by multiple genes.As novel research material,chromosome single segment substitution lines are useful in QTL identification because of minimizing the interference of genetic background among plants.In this study,QTLs for grain shape were identified with 119 rice chromosome single segment substitution lines derived from Nipponbare as donor parent in the background of Guanglu'ai 4 by one-way analysis of variance and Dunnett's test for means comparisons between chromosome single segment substitution lines and the recipient parent Guanglu'ai 4.A total of 39 QTLs for grain shape were identified on 11 chromosomes except chromosome 10 with a significance of P≤0.001.Among them,19 QTLs were identified for grain length,with the additive effect from 0.18 mm to 1.06 mm and the additive effect percentages from 2.40% to 14.13%;14 QTLs were identified for grain width,with the additive effect from 0.09 mm to 0.31 mm and the additive effect percentages from 2.71% to 9.15%;and 6 QTLs were identified for grain thickness,with the additive effect from 0.05 mm to 0.10 mm and the additive effect percentages from 2.14% to 4.46%.The results are important for the QTLs cloning and molecular breeding of rice grain shape.

Rotaviruses (RVs) are the leading cause of diarrhoea in cattle and buffalo calves worldwide. A total of 100 faecal samples were collected from the diarrhoeic cattle and buffalo calves from the organised dairy farms in the Mathura region. Extraction of viral RNA was done in 10% faecal suspension using phenol: chloroform/TRI reagent. The extracted RNA was subjected to RNA-polyacrylamide gel electrophoresis and silver staining. In total, 12 samples were positive for Group A RV, showing 11 segments of RNA genome of the virus in the pattern 4:2:3:2. Based on the migration of segments 10 and 11, all positive samples were characterised as long electropherotypes. Differences in the migration pattern of class I segments was observed. In type 1 pattern, all the four segments (1, 2, 3 and 4) migrated separately. In type 2 pattern, segments 2 and 3 co-migrated. In all the samples, class III segments (7, 8 and 9) moved as a single segment. One sample showed the presence of an additional band between gene segments 5 and 6. Multiple bands were present in two samples. A 12% prevalence of Group A bovine RV was found in the present study in the Mathura region. The samples were positive in the months of August-November and in calves aged below 1 month.