High-quality rice reference genomes have accelerated the comprehensive identification of genome-wide variations and research on functional genomics and breeding. Tian-you-hua-zhan has been a leading hybrid in China over the past decade. Here, de novo genome assembly strategy optimization for the rice indica lines Huazhan (HZ) and Tianfeng (TF), including sequencing platforms, assembly pipelines and sequence depth, was carried out. The PacBio and Nanopore platforms for long-read sequencing were utilized, with the Canu, wtdbg2, SMARTdenovo, Flye, Canu-wtdbg2, Canu-SMARTdenovo and Canu-Flye assemblers. The combination of PacBio and Canu was optimal, considering the contig N50 length, contig number, assembled genome size and polishing process. The assembled contigs were scaffolded with Hi-C data, resulting in two “golden quality” rice reference genomes, and evaluated using the scaffold N50, BUSCO, and LTR assembly index. Furthermore, 42,625 and 41,815 non-transposable element genes were annotated for HZ and TF, respectively. Based on our assembly of HZ and TF, as well as Zhenshan97, Minghui63, Shuhui498 and 9311, comprehensive variations were identified using Nipponbare as a reference. The de novo assembly strategy for rice we optimized and the “golden quality” rice genomes we produced for HZ and TF will benefit rice genomics and breeding research, especially with respect to uncovering the genomic basis of the elite traits of HZ and TF.
Welwitschia mirabilis, which is endemic to the Namib Desert, is the only living species within the family Welwitschiaceae. This species has an extremely long lifespan of up to 2,000 years and bears a single pair of opposite leaves that persist whilst alive. However, the underlying genetic mechanisms and evolution of the species remain poorly elucidated. Here, we report on a chromosome-level genome assembly for W. mirabilis, with a 6.30-Gb genome sequence and contig N50 of 27.50 Mb. In total, 39,019 protein-coding genes were predicted from the genome. Two brassinosteroid-related genes (BRI1 and CYCD3), key regulators of cell division and elongation, were strongly selected in W. mirabilis and may contribute to their long ever-growing leaves. Furthermore, 29 gene families in the mitogen-activated protein kinase signalling pathway showed significant expansion, which may contribute to the desert adaptations of the plant. Three positively selected genes (EHMT1, EIF4E, SOD2) may be involved in the mechanisms leading to long lifespan. Based on molecular clock dating and fossil calibrations, the divergence time of W. mirabilis and Gnetum montanum was estimated at ~123.5 million years ago. Reconstruction of population dynamics from genome data coincided well with the aridification of the Namib Desert. The genome sequence detailed in the current study provides insight into the evolution of W. mirabilis and should be an important resource for further study on gnetophyte and gymnosperm evolution. 相似文献
Probiotics and Antimicrobial Proteins - Gastrointestinal mucositis associated with the use of chemotherapeutic drugs can seriously affect the quality of life of patients. In this study, a probiotic... 相似文献
以山梨猕猴桃(Actinidia rufa(Siebold and Zuccarini)Planchon ex Miquel)品种‘63101’和中华猕猴桃(Actinidia chinensis var. chinensis C. F. Liang)品种‘磨山雄7号’杂交产生的400余株F1代个体为材料,连续2~3年对其果实品质和外观特点的9个性状进行测定,分析它们的遗传规律。结果显示 ,子代群体单果质量连续3年低于双亲中值,遗传传递力连续3年低于100%,优势率连续3年均为负值;可溶性固形物子代中值除2015年略低外,其余2年均高于亲中值12.3%;优势率均为正值,遗传传递力均大于100%;子代果实形状出现分离,与母本圆柱形相同的比例占82%;果皮毛被中,偏离母本的有毛比例为60%;果皮颜色出现绿色、绿褐色、褐色的分离,比例为1∶1.5∶1;果实肩部形状多与母本的方形相似,占比为63%;果肉颜色也多与母本的绿色相似,占比为 86%;果实风味中,与父本和母本相似的表型占比均为32%,口感酸的占比18%,超低亲极酸占比1%,超高亲浓甜占比9%。说明杂交子代单果质量和可溶性固形物含量分别表现为趋小和趋高的遗传倾向;果实形状、果实肩部形状和果肉颜色的遗传倾向于母本性状,而果皮毛被的遗传倾向偏离母本性状;果实风味具有广泛的性状分离现象,存在远高于高亲值和远低于低亲值的极端单株。研究结果说明这些子代材料有选育成为优良猕猴桃单株的潜力。 相似文献
The selective delivery of therapeutic agents to receptors overexpressed in cancer cells without harming the rest of the body is a major challenge in clinical oncology today. In this study, we report the design and synthesis of paclitaxel (PTX) conjugated with an erbB2-recognizing peptide (EC-1). The cyclic peptide EC-1 specifically binds to the extracellular domain of ErbB2 and selectively inhibits proliferation of breast cancer cells overexpressing ErbB2. PTX is a potent antitumor agent commonly used in the treatment of advanced metastatic breast cancer, yet patients have to suffer some side effects caused by its systemic toxicity. The aim of our conjugate is to specifically deliver antitumor agent PTX to breast cancer cells that overexpress oncogenic ErbB2 with the purpose to reduce toxicity and enhance selective killing of cancer cells. In this study, a concise and efficient synthetic route for the preparation of the PTX-EC-1 conjugate has been developed in 6% overall yield. This synthetic approach provides a general method for conjugating a highly functionalized and disulfide-bridge containing cyclopeptide to Taxol or other antitumor agents. 相似文献