RESUMEN
Lipomas are superficial tumors that occur primarily in the subcutaneous region and very rarely occur deeply within or between the muscle layers. No reports to date have described cervical lipomas in patients with head and neck cancer who underwent neck dissection. We herein report a case involving a 72-year-old woman with supraglottic carcinoma complicated by a cervical lipoma who underwent simultaneous neck dissection and lipoma removal. The lipoma was a deep-seated intermuscular lipoma arising in the longus cervicis muscle. We initially considered that the lipoma would be removed en bloc with neck dissection, but the imaging findings clearly indicated that the tumor was located more deeply than the prevertebral layer of the deep cervical fascia and outside the range of neck dissection. The lipoma was removed by incision of the prevertebral fascial layer following neck dissection, and no complications occurred.
RESUMEN
Direct seeding is employed to circumvent the labor-intensive process of rice (Oryza sativa) transplantation, but this approach requires varieties with vigorous low-temperature germination (LTG) when sown in cold climates. To investigate the genetic basis of LTG, we identified the quantitative trait locus (QTL) qLTG11 from rice variety Arroz da Terra, which shows rapid seed germination at lower temperatures, using QTL-seq. We delineated the candidate region to a 52-kb interval containing GENERAL REGULATORY FACTOR14h (GF14h) gene, which is expressed during seed germination. The Arroz da Terra GF14h allele encodes functional GF14h, whereas Japanese rice variety Hitomebore harbors a 4-bp deletion in the coding region. Knocking out functional GF14h in a near-isogenic line (NIL) carrying the Arroz da Terra allele decreased LTG, whereas overexpressing functional GF14h in Hitomebore increased LTG, indicating that GF14h is the causal gene behind qLTG11. Analysis of numerous Japanese rice accessions revealed that the functional GF14h allele was lost from popular varieties during modern breeding. We generated a NIL in the Hitomebore background carrying a 172-kb genomic fragment from Arroz da Terra including GF14h. The NIL showed superior LTG compared to Hitomebore, with otherwise comparable agronomic traits. The functional GF14h allele from Arroz da Terra represents a valuable resource for direct seeding in cold regions.
Asunto(s)
Frío , Regulación de la Expresión Génica de las Plantas , Germinación , Oryza , Fitomejoramiento , Proteínas de Plantas , Sitios de Carácter Cuantitativo , Semillas , Oryza/genética , Oryza/crecimiento & desarrollo , Germinación/genética , Proteínas de Plantas/genética , Semillas/genética , Semillas/crecimiento & desarrollo , Fitomejoramiento/métodos , Alelos , Mapeo Cromosómico/métodosRESUMEN
We investigated the variation and geographical distribution of the Pseudo-regulator response 37 (Setaria italica PRR37; SiPRR37) gene, which is involved in heading time (photoperiodism) in foxtail millet. An allele of the SiPRR37 gene, in which an approximately 4.9-kb transposable element (designated TE1) is inserted (a loss-of-function or reduction-of-function type), is distributed sporadically in East Asia and broadly in Southeast Asia and South Asia, implying that this gene is important in latitudinal adaptation. In addition, we found a new allele of SiPRR37 with an insertion of a 360-bp TE (TE2) at this locus and investigated the geographical distribution of this new type. This SiPRR37 allele with TE2 is distributed in Japan, Korea, Nepal, Iran and Turkey. Both TE1 and TE2 are useful markers for tracing foxtail millet dispersal pathways in Asia.
Asunto(s)
Elementos Transponibles de ADN , Setaria (Planta) , Setaria (Planta)/genética , Elementos Transponibles de ADN/genética , Proteínas de Plantas/genética , Alelos , Adaptación Fisiológica/genética , Genes de PlantasRESUMEN
DNA markers are indispensable tools in genetics and genomics research as well as in crop breeding, particularly for marker-assisted selection. Recent advances in next-generation sequencing technology have made it easier to obtain genome sequences for various crop species, enabling the large-scale identification of DNA polymorphisms among varieties, which in turn has made DNA marker design more accessible. However, existing primer design software is not suitable for designing many types of genome-wide DNA markers from next-generation sequencing data. Here, we describe the development of V-primer, high-throughput software for designing insertion/deletion, cleaved amplified polymorphic sequence, and single-nucleotide polymorphism (SNP) markers. We validated the applicability of these markers in different crops. In addition, we performed multiplex PCR targeted amplicon sequencing using SNP markers designed with V-primer. Our results demonstrate that V-primer facilitates the efficient and accurate design of primers and is thus a useful tool for genetics, genomics, and crop breeding. V-primer is freely available at https://github.com/ncod3/vprimer.
RESUMEN
Background: Persistent opioid use frequently leads to substantial negative impacts on quality of life, and as the outlook for numerous cancer types continues to improve, these complications become increasingly crucial. It is essential to acknowledge that extended or excessive opioid use may result in adverse effects in patients who completed radiation therapy (RT). Methods: In this time-series analysis, we compared the outcomes of patients who participated in the pharmacist-led opioid de-escalation (PLODE) program after completing concurrent radiotherapy (CRT) between June 2018 and February 2019 against patients who completed CRT between June 2017 and March 2018 and did not participate in the program. Results: Among 61 patients, 16 (26%) used opioids after completing CRT and participated in the PLODE program. Before starting the program, 93 patients completed CRT between June 2017 and March 2018 and 32 (34%) used opioids at CRT completion. These patients were deemed the control group. In the PLODE group, outpatient pharmacist intervention was performed, with 29 total interventions related to opioid use, of which 16 (55%) recommended tapering or discontinuing opioids according to the definition of this program. Patients who participated in the PLODE program discontinued opioids significantly earlier than those in the control group (median time to opioid discontinuation 11 days vs. 24.5 days, p < 0.001). None of the patients in the PLODE group resumed opioid use following discontinuation or escalated opioid dosing due to worsening pain. Conclusion: This study showed the utility of pharmacist-initiated interventions for opioid use in patients with head and neck cancer who had completed CRT.
RESUMEN
Background: In the phase 3 SELECT study, lenvatinib significantly improved prognostic outcomes vs. placebo in patients with radioiodine-refractory differentiated thyroid cancer (RR-DTC). However, toxicity of lenvatinib is sometimes considerable and requires frequent dose interruptions and modifications. Recently, planned drug holidays have been proposed as a means of avoiding severe adverse events (AEs). Methods: We retrospectively reviewed medical records to compare the efficacy and safety of lenvatinib in RR-DTC patients who underwent planned drug holidays (planned holiday group) vs. those who received conventional daily oral administration (daily group). Results: The subjects were 25 patients in the planned holiday group and 21 in the daily group. Median age was 73 years (range 43-84) and 62 years (range 42-75), and histologic subtype of papillary/follicular was 21/4 cases and 15/6 cases, respectively. Time to treatment failure (TTF) and overall survival (OS) were significantly longer in the planned holiday group than the daily group (not reached [NR] vs. 14.9 months, hazard ratio [HR] 0.25, 95% confidence interval [Cl] 0.11-0.58, p<0.001; NR vs. 26.6 months, HR 0.20, 95% CI 0.073-0.58, p=0.001, respectively). Median progression-free survival (PFS) was NR in the planned holiday group vs. 15.1 months in the daily group (HR 0.31, 95% CI 0.14-0.68, p=0.002). Duration of the period with lenvatinib dose ≥10 mg was significantly longer in the planned holiday group (NR vs. 6.5 months, HR 0.22, 95% CI 0.10-0.49, p<0.001), and the frequency of drug interruption due to intolerable AEs was lower (68.0% vs. 95.2%, p=0.027). Conclusion: Planned drug holidays for lenvatinib demonstrated significantly longer PFS, TTF, and OS than daily oral administration, and less intolerable toxicity leading to further unplanned treatment interruption. These benefits were apparently associated with a more extended period of lenvatinib administration at ≥10 mg. These findings might contribute to a favorable patient prognosis and safer toxicity profile.
RESUMEN
BACKGROUND: Pain and post-operative nausea and vomiting are the main factors that impair the quality of recovery after surgery. Very few reports have analyzed patient-reported outcomes to investigate the efficacy of an enhanced recovery after surgery protocol to alleviate these symptoms after head and neck surgeries with free tissue transfer reconstruction. METHODS: We investigated post-operative pain and post-operative nausea and vomiting in 47 patients who underwent head and neck surgeries with free tissue transfer reconstruction with enhanced recovery after surgery support between February 2021 and August 2022. Patient-reported outcomes were assessed using the visual analog scale and Japanese version of the Quality of Recovery-40. RESULTS: Significant increases in the mean visual analog scale scores for pain and post-operative nausea and vomiting were observed only on post-operative Day 1 compared with preoperative values (pain: 3.19 ± 2.78 vs. 1.96 ± 2.42, P = 0.0408; post-operative nausea and vomiting: 1.52 ± 2.09 vs. 0.54 ± 1.37, P = 0.0194). From post-operative Day 2, there were no significant differences between the pre- and post-operative visual analog scale scores, and no significant increases in the incidences of moderate or severe pain and post-operative nausea and vomiting compared with preoperatively. The Japanese version of the Quality of Recovery-40 score for post-operative pain showed no significant deterioration compared with preoperatively, while the Japanese version of the Quality of Recovery-40 score for post-operative nausea and vomiting showed significant deterioration compared with the preoperative value on post-operative Days 2, 4 and 7. CONCLUSIONS: The visual analog scale and Japanese version of the Quality of Recovery-40 scores for post-operative pain and visual analog scale score for post-operative nausea and vomiting suggested that the enhanced recovery after surgery strategy favorably controlled pain and post-operative nausea and vomiting after head and neck surgeries with free tissue transfer reconstruction. However, as the post-operative Japanese version of the Quality of Recovery-40 score for post-operative nausea and vomiting was lower than the preoperative value, there is still a need for further improvement of the enhanced recovery after surgery pathway.
Asunto(s)
Recuperación Mejorada Después de la Cirugía , Humanos , Náusea y Vómito Posoperatorios/etiología , Manejo del Dolor , Dolor Postoperatorio/etiologíaRESUMEN
Background: Despite advances in precision medicine, most patients with recurrent or metastatic salivary gland carcinoma still need conventional chemotherapies, such as the combination of taxane and platinum. However, evidence for these standardized regimens is limited. Methods: We retrospectively reviewed patients with salivary gland carcinoma treated with a taxane and platinum, which contained docetaxel at a dose of 60 mg/m2 plus cisplatin at a dose of 70 mg/m2 on day 1, or paclitaxel at a dose of 100 mg/m2 plus carboplatin at a dose of area under the plasma concentration-time curve = 2.5 on days 1 and 8 (both on 21-day cycles), between January 2000 and September 2021. Result: Forty patients with ten adenoid cystic carcinomas and thirty other pathologies were identified. Of these, 29 patients were treated with docetaxel plus cisplatin and 11 with paclitaxel plus carboplatin. For the total population, the objective response rate (ORR) and median progression-free survival (mPFS) were 37.5% and 5.4 months (95% confidence interval: 3.6-7.4 months), respectively. On subgroup analysis, docetaxel plus cisplatin provided favorable efficacy compared with paclitaxel plus carboplatin (ORR: 46.5% vs. 20.0%, mPFS: 7.2 vs. 2.8 months), and the findings were well retained in patients with adenoid cystic carcinoma (ORR: 60.0% vs. 0%, mPFS: 17.7 vs. 2.8 months). Grade 3/4 neutropenia was relatively frequent in the docetaxel plus cisplatin (59% vs.27%), although febrile neutropenia was uncommon (3%) in the cohort. No treatment-related death was seen in any case. Conclusion: The combination of taxane and platinum is generally effective and well-tolerated for recurrent or metastatic salivary gland carcinoma. In contrast, paclitaxel plus carboplatin appears unfavorable in terms of efficacy in certain patients, such as those with adenoid cystic carcinoma.
RESUMEN
Studies focused solely on single organisms can fail to identify the networks underlying host-pathogen gene-for-gene interactions. Here, we integrate genetic analyses of rice (Oryza sativa, host) and rice blast fungus (Magnaporthe oryzae, pathogen) and uncover a new pathogen recognition specificity of the rice nucleotide-binding domain and leucine-rich repeat protein (NLR) immune receptor Pik, which mediates resistance to M. oryzae expressing the avirulence effector gene AVR-Pik. Rice Piks-1, encoded by an allele of Pik-1, recognizes a previously unidentified effector encoded by the M. oryzae avirulence gene AVR-Mgk1, which is found on a mini-chromosome. AVR-Mgk1 has no sequence similarity to known AVR-Pik effectors and is prone to deletion from the mini-chromosome mediated by repeated Inago2 retrotransposon sequences. AVR-Mgk1 is detected by Piks-1 and by other Pik-1 alleles known to recognize AVR-Pik effectors; recognition is mediated by AVR-Mgk1 binding to the integrated heavy metal-associated (HMA) domain of Piks-1 and other Pik-1 alleles. Our findings highlight how complex gene-for-gene interaction networks can be disentangled by applying forward genetics approaches simultaneously to the host and pathogen. We demonstrate dynamic coevolution between an NLR integrated domain and multiple families of effector proteins.
Asunto(s)
Oryza , Receptores Inmunológicos , Receptores Inmunológicos/metabolismo , Hongos/metabolismo , Enfermedades de las Plantas/microbiología , Interacciones Huésped-Patógeno/genética , Oryza/genética , Oryza/microbiología , Proteínas de Plantas/genética , Proteínas de Plantas/metabolismoRESUMEN
OBJECTIVES: In CheckMate 141, nivolumab significantly improved overall survival (OS) in patients with platinum-refractory recurrent or metastatic squamous cell carcinomas (R/M SCC) of the head and neck. However, reports on nivolumab for patients with non-SCC and/or a primary subsite excluded from CheckMate 141 are limited. MATERIALS AND METHODS: We conducted a retrospective analysis of R/M head and neck cancer patients who received nivolumab. The study subject excluded patients with squamous cell carcinoma of the oral cavity, oropharynx, hypopharynx, and larynx. RESULTS: A total of 59 patients were included, consisting of 40 males and 19 females with a median age of 61 years. Half of the patients had non-SCC histology. The main primary site included the sinonasal cavity (n = 18), salivary gland (n = 15), and nasopharynx (n = 13). Three (6.0%) patients achieved a complete response and 5 (10.0%) a partial response, giving an overall response rate (ORR) of 16.6%. Median time-to-treatment failure (TTF) and OS were 3.7 and 16.2 months, respectively. Salivary gland and nasopharyngeal cancer achieved relatively higher ORR (25.0 and 36.4%, respectively). On analysis by primary site, nasopharyngeal cancer showed a significantly better TTF and OS than the other primary sites. On analysis by histological findings, no significant difference in TTF and OS was observed between non-SCC and SCC. CONCLUSION: Nivolumab for cancers involving the salivary gland/nasopharynx and non-SCC histology showed comparable efficacy to that in CheckMate 141. This result indicates that nivolumab may be effective even for patients not included in CheckMate 141.
Asunto(s)
Carcinoma de Células Escamosas , Neoplasias de Cabeza y Cuello , Neoplasias Nasofaríngeas , Femenino , Neoplasias de Cabeza y Cuello/tratamiento farmacológico , Humanos , Masculino , Persona de Mediana Edad , Recurrencia Local de Neoplasia/patología , Nivolumab/uso terapéutico , Estudios Retrospectivos , Carcinoma de Células Escamosas de Cabeza y Cuello/tratamiento farmacológicoRESUMEN
We constructed recombinant inbred lines (RILs) between a Japanese and a Taiwanese landrace of foxtail millet and employed next-generation sequencing, such as flexible ddRAD-seq and Nanopore sequencing to identify the candidate genes involved in the crop evolution of foxtail millet. We successfully constructed a linkage map using flexible ddRAD-seq with parents and RILs and detected major QTLs for each of three traits: leaf sheath colors, spikelet-tipped bristles (stb), and days to heading (DTH). (1) For leaf sheath colors, we identified the C gene on chromosome IV. (2) We identified a homeobox (HOX14) gene for stb on chromosome II, which shows homology with HvVrs1 in barley. (3) Finally, we identified a QTL with a large effect on DTH on chromosome II. A parent of the RILs from Taiwan and Yugu1 had a Harbinger-like TE in intron 3 of this gene. We also investigated the geographical distribution of the TE insertion type of this gene and found that the insertion type is distributed in the northern part of East Asia and intensively in South and Southeast Asia, suggesting that loss/reduction of function of this gene plays an important role in spreading into the northern part of East Asia and subtropical and tropical zones.
Asunto(s)
Cromosomas de las Plantas/genética , Setaria (Planta)/genética , Genoma de Planta , Secuenciación de Nucleótidos de Alto Rendimiento , Proteínas de Homeodominio/genética , Hordeum/genética , Endogamia , Japón , Fenotipo , Fitomejoramiento , Proteínas de Plantas/genética , Sitios de Carácter Cuantitativo , Setaria (Planta)/crecimiento & desarrollo , TaiwánRESUMEN
White Guinea yam (Dioscorea rotundata) is an important staple tuber crop in West Africa. However, its origin remains unclear. In this study, we resequenced 336 accessions of white Guinea yam and compared them with the sequences of wild Dioscorea species using an improved reference genome sequence of D. rotundata In contrast to a previous study suggesting that D. rotundata originated from a subgroup of Dioscorea praehensilis, our results suggest a hybrid origin of white Guinea yam from crosses between the wild rainforest species D. praehensilis and the savannah-adapted species Dioscorea abyssinica We identified a greater genomic contribution from D. abyssinica in the sex chromosome of Guinea yam and extensive introgression around the SWEETIE gene. Our findings point to a complex domestication scenario for Guinea yam and highlight the importance of wild species as gene donors for improving this crop through molecular breeding.
Asunto(s)
Productos Agrícolas/genética , Dioscorea/genética , Genoma de Planta , Hibridación Genética , Cromosomas de las Plantas/genética , ADN de Plantas/genética , Domesticación , Guinea , Filogenia , Fitomejoramiento/métodos , Tubérculos de la Planta , Polimorfismo de Nucleótido Simple , Cromosomas Sexuales/genéticaRESUMEN
Background: Platinum-containing doublet chemotherapy regimens are generally considered the standard first-line systemic therapy for recurrent or metastatic (R/M) nasopharyngeal cancer (NPC). Gemcitabine (GEM) plus cisplatin (CDDP) has become a standard therapy based on a phase 3 study in several countries, yet this regimen sometimes affects quality of life due to nausea or appetite loss. Here, we present the manageable toxicity and promising activity of paclitaxel + carboplatin + cetuximab (PCE) therapy for R/M NPC. Materials and Methods: We conducted a retrospective review of patients with R/M NPC who were treated with PCE from 2013 to 2019 at the National Cancer Center East, Kashiwa, Japan. PCE consisted of PTX 100 mg/m2 on days 1 and 8; CBDCA area under the blood concentration-time curve (AUC) 2.5 on days 1 and 8, repeated every 3 weeks; and cetuximab at an initial dose of 400 mg/m2, followed by 250 mg/m2 weekly, as reported in the paper. Results: Fourteen patients were identified, consisting of 10 males and 4 females with a median age 59.6 years (range, 43-74). Among the 12 of 14 patients assessed for efficacy, overall response rate was 58.3%, with 2 complete responses and 5 partial responses. On median follow-up of 23.8 months, median overall survival was not reached with observed death events of 2. Median PFS was 4.1 months (95% CI, 2.6-5.6 months). Two patients experienced disease progression during cetuximab maintenance and restarted PCE treatment, then achieved partial response again. The most common grade 3 or 4 adverse events were neutropenia (21.4%) and skin reaction (14.3%). No treatment-related death was observed. Conclusion: Although the number of study population was small, our results suggest that PCE is feasible and potentially effective for R/M NPC, with a 58.3% response rate and 4.1-month PFS. Further prospective evaluation is warranted.
RESUMEN
Soybean [Glycine max (L) Merrill] is one of the most important leguminous crops and ranks fourth after to rice, wheat and maize in terms of world crop production. Soybean contains abundant protein and oil, which makes it a major source of nutritious food, livestock feed and industrial products. In Japan, soybean is also an important source of traditional staples such as tofu, natto, miso and soy sauce. The soybean genome was determined in 2010. With its enormous size, physical mapping and genome sequencing are the most effective approaches towards understanding the structure and function of the soybean genome. We constructed bacterial artificial chromosome (BAC) libraries from the Japanese soybean cultivar, Enrei. The end-sequences of approximately 100,000 BAC clones were analyzed and used for construction of a BAC-based physical map of the genome. BLAST analysis between Enrei BAC-end sequences and the Williams82 genome was carried out to increase the saturation of the map. This physical map will be used to characterize the genome structure of Japanese soybean cultivars, to develop methods for the isolation of agronomically important genes and to facilitate comparative soybean genome research. The current status of physical mapping of the soybean genome and construction of database are presented.
RESUMEN
Rice (Oryza sativa L.) is a model organism for the functional genomics of monocotyledonous plants since the genome size is considerably smaller than those of other monocotyledonous plants. Although highly accurate genome sequences of indica and japonica rice are available, additional resources such as full-length complementary DNA (FL-cDNA) sequences are also indispensable for comprehensive analyses of gene structure and function. We cross-referenced 28.5K individual loci in the rice genome defined by mapping of 578K FL-cDNA clones with the 56K loci predicted in the TIGR genome assembly. Based on the annotation status and the presence of corresponding cDNA clones, genes were classified into 23K annotated expressed (AE) genes, 33K annotated non-expressed (ANE) genes, and 5.5K non-annotated expressed (NAE) genes. We developed a 60mer oligo-array for analysis of gene expression from each locus. Analysis of gene structures and expression levels revealed that the general features of gene structure and expression of NAE and ANE genes were considerably different from those of AE genes. The results also suggested that the cloning efficiency of rice FL-cDNA is associated with the transcription activity of the corresponding genetic locus, although other factors may also have an effect. Comparison of the coverage of FL-cDNA among gene families suggested that FL-cDNA from genes encoding rice- or eukaryote-specific domains, and those involved in regulatory functions were difficult to produce in bacterial cells. Collectively, these results indicate that rice genes can be divided into distinct groups based on transcription activity and gene structure, and that the coverage bias of FL-cDNA clones exists due to the incompatibility of certain eukaryotic genes in bacteria.
Asunto(s)
ADN Complementario/genética , ADN de Plantas/genética , Perfilación de la Expresión Génica , Oryza/genética , Mapeo Cromosómico , Exones , IntronesRESUMEN
The genomic sequences derived from rice centromeric regions were analyzed to facilitate the comprehensive understanding of the rice genome. A rice centromere-specific satellite sequence, RCS2/TrsD/CentO, was used to screen P1-derived artificial chromosome (PAC) and bacterial artificial chromosome (BAC) genomic libraries derived from Oryza sativa L. ssp. japonica cultivar Nipponbare. Physical maps of the centromeric regions were constructed by DNA fingerprinting methods and the aligned clones were analyzed by end sequencing. BLAST analysis revealed the composition of genes, centromeric satellites and other repetitive elements, such as RIRE7/CRR, RIRE8, Squiq, Anaconda, CACTA and miniature inverted-repeat transposable elements. Fiber-fluorescent in situ hybridization analysis also indicated the presence of distinct clusters of RCS2/TrsD/CentO satellite interspersed with other elements, instead of a long homogeneous region. Several expressed genes, sequences representative of ancestral organellar insertions, relatively long simple sequence repeats (SSRs), and sequences corresponding to 5S and 45S ribosomal RNA genes were also identified. Thirty-one gene sequences showed high-similarity to rice full-length cDNA sequences that had not been matched to the published rice genome sequence in silico. These results suggest the presence of expressed genes within and around the clusters of RCS2/TrsD/CentO satellites in unsequenced centromeric regions of the rice chromosomes.
Asunto(s)
Centrómero/genética , Cromosomas de las Plantas/ultraestructura , Elementos Transponibles de ADN/genética , Oryza/genética , Secuencias Repetitivas de Ácidos Nucleicos/genética , Cromosomas Artificiales Bacterianos , Cromosomas de las Plantas/genética , ADN de Plantas , Repeticiones de MicrosatéliteRESUMEN
Understanding the organization of eukaryotic centromeres has both fundamental and applied importance because of their roles in chromosome segregation, karyotypic stability, and artificial chromosome-based cloning and expression vectors. Using clone-by-clone sequencing methodology, we obtained the complete genomic sequence of the centromeric region of rice (Oryza sativa) chromosome 8. Analysis of 1.97 Mb of contiguous nucleotide sequence revealed three large clusters of CentO satellite repeats (68.5 kb of 155-bp repeats) and >220 transposable element (TE)-related sequences; together, these account for approximately 60% of this centromeric region. The 155-bp repeats were tandemly arrayed head to tail within the clusters, which had different orientations and were interrupted by TE-related sequences. The individual 155-bp CentO satellite repeats showed frequent transitions and transversions at eight nucleotide positions. The 40 TE elements with highly conserved sequences were mostly gypsy-type retrotransposons. Furthermore, 48 genes, showing high BLAST homology to known proteins or to rice full-length cDNAs, were predicted within the region; some were close to the CentO clusters. We then performed a genome-wide survey of the sequences and organization of CentO and RIRE7 families. Our study provides the complete sequence of a centromeric region from either plants or animals and likely will provide insight into the evolutionary and functional analysis of plant centromeres.
Asunto(s)
Cromosomas de las Plantas/genética , Oryza/genética , Composición de Base , Secuencia de Bases , Centrómero/genética , Cromosomas Artificiales Bacterianos/genética , Cromosomas Artificiales de Bacteriófagos P1/genética , Secuencia Conservada , Elementos Transponibles de ADN/genética , ADN de Plantas/química , ADN de Plantas/genética , ADN Satélite/genética , Genoma de Planta , Datos de Secuencia Molecular , Mapeo Físico de Cromosoma , Secuencias Repetitivas de Ácidos NucleicosRESUMEN
We constructed physical maps of rice chromosomes 1, 2, and 6-9 with P1-derived artificial chromosome (PAC) and bacterial artificial chromosome (BAC) clones. These maps, with only 20 gaps, cover more than 97% of the predicted length of the six chromosomes. We submitted a total of 193 Mbp of non-overlapping sequences to public databases. We analyzed the DNA sequences of 1316 genetic markers and six centromere-specific repeats to facilitate characterization of chromosomal recombination frequency and of the genomic composition and structure of the centromeric regions. We found marked changes in the relative recombination rate along the length of each chromosome. Chromosomal recombination at the centromere core and surrounding regions on the six chromosomes was completely suppressed. These regions have a total physical length of about 23 Mbp, corresponding to 11.4% of the entire size of the six chromosomes. Chromosome 6 has the longest quiescent region, with about 5.6 Mbp, followed by chromosome 8, with quiescent region about half this size. Repetitive sequences accounted for at least 40% of the total genomic sequence on the partly sequenced centromeric region of chromosome 1. Rice CentO satellite DNA is arrayed in clusters and is closely associated with the presence of Centromeric Retrotransposon of Rice (CRR)- and RIce RetroElement 7 (RIRE7)-like retroelement sequences. We also detected relatively small coldspot regions outside the centromeric region; their repetitive content and gene density were similar to those of regions with normal recombination rates. Sequence analysis of these regions suggests that either the amount or the organization patterns of repetitive sequences may play a role in the inactivation of recombination.