Search tips
Search criteria

Results 1-9 (9)

Clipboard (0)

Select a Filter Below

Year of Publication
Document Types
1.  Genetic Diversity and Geographical Distribution of Indigenous Soybean-Nodulating Bradyrhizobia in the United States 
Applied and Environmental Microbiology  2013;79(12):3610-3618.
We investigated the relationship between the genetic diversity of indigenous soybean-nodulating bradyrhizobia and their geographical distribution in the United States using nine soil isolates from eight states. The bradyrhizobia were inoculated on three soybean Rj genotypes (non-Rj, Rj2Rj3, and Rj4). We analyzed their genetic diversity and community structure by means of restriction fragment length polymorphisms of PCR amplicons to target the 16S-23S rRNA gene internal transcribed spacer region, using 11 USDA Bradyrhizobium strains as reference strains. We also performed diversity analysis, multidimensional scaling analysis based on the Bray-Curtis index, and polar ordination analysis to describe the structure and geographical distribution of the soybean-nodulating bradyrhizobial community. The major clusters were Bradyrhizobium japonicum Bj123, in the northern United States, and Bradyrhizobium elkanii, in the middle to southern regions. Dominance of bradyrhizobia in a community was generally larger for the cluster belonging to B. elkanii than for the cluster belonging to B. japonicum. The indigenous American soybean-nodulating bradyrhizobial community structure was strongly correlated with latitude. Our results suggest that this community varies geographically.
PMCID: PMC3675916  PMID: 23563944
2.  Effect of Rj Genotype and Cultivation Temperature on the Community Structure of Soybean-Nodulating Bradyrhizobia 
The nodulation tendency and community structure of indigenous bradyrhizobia on Rj genotype soybean cultivars at cultivation temperatures of 33/28°C, 28/23°C, and 23/18°C for 16/8 h (day/night degrees, hours) were investigated using 780 bradyrhizobial DNA samples from an Andosol with 13 soybean cultivars of four Rj genotypes (non-Rj, Rj2Rj3, Rj4, and Rj2Rj3Rj4). A dendrogram was constructed based on restriction fragment length polymorphism of the PCR products (PCR-RFLP) of the 16S-23S rRNA gene internal transcribed spacer region. Eleven Bradyrhizobium U.S. Department of Agriculture strains were used as a reference. The dendrogram indicated seven clusters based on similarities among the reference strains. The occupancy rate of the Bj123 cluster decreased with increasing cultivation temperature, whereas the occupancy rates of the Bj110 cluster, Be76 cluster, and Be94 cluster increased with increasing cultivation temperature. In particular, the Rj2Rj3Rj4 genotype soybeans were infected with a number of Bj110 clusters, regardless of the increasing cultivation temperature, compared to other Rj genotype soybean cultivars. The ratio of beta diversity to gamma diversity (H′β/H′γ), which represents differences in the bradyrhizobial communities by pairwise comparison among cultivation temperature sets within the same soybean cultivar, indicated that the bradyrhizobial communities tended to be different among cultivation temperatures. Multidimensional scaling analysis indicated that the infection of the Bj110 cluster and the Bj123 cluster by host soybean genotype and the cultivation temperature affected the bradyrhizobial communities. These results suggested that the Rj genotypes and cultivation temperatures affected the nodulation tendency and community structures of soybean-nodulating bradyrhizobia.
PMCID: PMC3272988  PMID: 22156423
3.  Rj (rj) genes involved in nitrogen-fixing root nodule formation in soybean 
Breeding Science  2012;61(5):544-553.
It has long been known that formation of symbiotic root nodules in soybean (Glycine max (L.) Merr.) is controlled by several host genes referred to as Rj (rj) genes, but molecular cloning of these genes has been hampered by soybean’s complicated genome structure and large genome size. Progress in molecular identification of legume genes involved in root nodule symbiosis have been mostly achieved by using two model legumes, Lotus japonicus and Medicago truncatula, that have relatively simple and small genomes and are capable of molecular transfection. However, recent development of resources for soybean molecular genetic research, such as genome sequencing, large EST databases, and high-density linkage maps, have enabled us to isolate several Rj genes. This progress has been achieved in connection with systematic utilization of the information obtained from molecular genetics of the model legumes. In this review, we summarize the current status of knowledge of host-controlled nodulation in soybean based on information from recent studies on Rj genes, and discuss the future research prospects.
PMCID: PMC3406786  PMID: 23136493
soybean; root nodule symbiosis; Rj (rj) gene; host-controlled nodulation; host-restriction of nodulation; autoregulation of nodulation; model legume
4.  Genetics of Endometrial Cancers 
Endometrial cancers exhibit a different mechanism of tumorigenesis and progression depending on histopathological and clinical types. The most frequently altered gene in estrogen-dependent endometrioid endometrial carcinoma tumors is PTEN. Microsatellite instability is another important genetic event in this type of tumor. In contrast, p53 mutations or Her2/neu overexpression are more frequent in non-endometrioid tumors. On the other hand, it is possible that the clear cell type may arise from a unique pathway which appears similar to the ovarian clear cell carcinoma. K-ras mutations are detected in approximately 15%–30% of endometrioid carcinomas, are unrelated to the existence of endometrial hyperplasia. A β-catenin mutation was detected in about 20% of endometrioid carcinomas, but is rare in serous carcinoma. Telomere shortening is another important type of genomic instability observed in endometrial cancer. Only non-endometrioid endometrial carcinoma tumors were significantly associated with critical telomere shortening in the adjacent morphologically normal epithelium. Lynch syndrome, which is an autosomal dominantly inherited disorder of cancer susceptibility and is characterized by a MSH2/MSH6 protein complex deficiency, is associated with the development of non-endometrioid carcinomas.
PMCID: PMC2852605  PMID: 20396392
5.  Sequencing and Analysis of Approximately 40 000 Soybean cDNA Clones from a Full-Length-Enriched cDNA Library 
A large collection of full-length cDNAs is essential for the correct annotation of genomic sequences and for the functional analysis of genes and their products. We obtained a total of 39 936 soybean cDNA clones (GMFL01 and GMFL02 clone sets) in a full-length-enriched cDNA library which was constructed from soybean plants that were grown under various developmental and environmental conditions. Sequencing from 5′ and 3′ ends of the clones generated 68 661 expressed sequence tags (ESTs). The EST sequences were clustered into 22 674 scaffolds involving 2580 full-length sequences. In addition, we sequenced 4712 full-length cDNAs. After removing overlaps, we obtained 6570 new full-length sequences of soybean cDNAs so far. Our data indicated that 87.7% of the soybean cDNA clones contain complete coding sequences in addition to 5′- and 3′-untranslated regions. All of the obtained data confirmed that our collection of soybean full-length cDNAs covers a wide variety of genes. Comparative analysis between the derived sequences from soybean and Arabidopsis, rice or other legumes data revealed that some specific genes were involved in our collection and a large part of them could be annotated to unknown functions. A large set of soybean full-length cDNA clones reported in this study will serve as a useful resource for gene discovery from soybean and will also aid a precise annotation of the soybean genome.
PMCID: PMC2608845  PMID: 18927222
EST; full-length cDNA; functional annotation; legume; soybean
6.  An Integrated High-density Linkage Map of Soybean with RFLP, SSR, STS, and AFLP Markers Using A Single F2 Population 
Soybean [Glycine max (L.) Merrill] is the most important leguminous crop in the world due to its high contents of high-quality protein and oil for human and animal consumption as well as for industrial uses. An accurate and saturated genetic linkage map of soybean is an essential tool for studies on modern soybean genomics. In order to update the linkage map of a F2 population derived from a cross between Misuzudaizu and Moshidou Gong 503 and to make it more informative and useful to the soybean genome research community, a total of 318 AFLP, 121 SSR, 108 RFLP, and 126 STS markers were newly developed and integrated into the framework of the previously described linkage map. The updated genetic map is composed of 509 RFLP, 318 SSR, 318 AFLP, 97 AFLP-derived STS, 29 BAC-end or EST-derived STS, 1 RAPD, and five morphological markers, covering a map distance of 3080 cM (Kosambi function) in 20 linkage groups (LGs). To our knowledge, this is presently the densest linkage map developed from a single F2 population in soybean. The average intermarker distance was reduced to 2.41 from 5.78 cM in the earlier version of the linkage map. Most SSR and RFLP markers were relatively evenly distributed among different LGs in contrast to the moderately clustered AFLP markers. The number of gaps of more than 25 cM was reduced to 6 from 19 in the earlier version of the linkage map. The coverage of the linkage map was extended since 17 markers were mapped beyond the distal ends of the previous linkage map. In particular, 17 markers were tagged in a 5.7 cM interval between CE47M5a and Satt100 on LG C2, where several important QTLs were clustered. This newly updated soybean linkage map will enable to streamline positional cloning of agronomically important trait locus genes, and promote the development of physical maps, genome sequencing, and other genomic research activities.
PMCID: PMC2779910  PMID: 18192280
soybean; linkage map; SSR; RFLP; AFLP; STS
7.  Fragment Maps of φX-174 Replicative DNA Produced by Restriction Enzymes from Haemophilus aphirophilus and Haemophilus influenzae H-I 
Journal of Virology  1974;14(5):1142-1151.
φX-174 replicative form (RF) DNA was cleaved by restriction enzymes from Haemophilus aphirophilus (Hap) and H. influenzae (H-I strain Osaka) (HinH). Five fragments were produced by Hap and eight by HinH. The positions of all of the Hap fragments and six of the HinH fragments were mapped on the genome by heteroduplex transfection and DNA-DNA hybridization methods. In addition, fragment sizes of φX-174 RF DNA and S13 RF DNA by Hap and HinH were compared. Considerable differences of the size of the fragments produced from these closely related phage genomes were observed.
PMCID: PMC355631  PMID: 4610178
8.  Isolation of ΦX174 Specific Messenger Ribonucleic Acids In Vivo and Identification of Their 5′ Terminal Nucleotides 
Journal of Virology  1972;9(2):207-215.
Deoxyribonucleic acid (DNA) and ribonucleic acid (RNA) hybridization in formamide at low temperature was applied to hybridization of ΦX174 replicative form DNA and in vivo ΦX174 specific messenger RNA (mRNA) with some modification. We found that ΦX174 mRNA up to molecular weight 1.2 × 106 could be hybridized to and eluted from DNA without apparent breakage of phosphodiester bonds and the 5′ terminal guanosine triphosphate and adenosine triphosphate of the RNA. By alkali hydrolysis of the purified in vivo ΦX174 mRNA and subsequent thin-layer chromatography of the digest, we isolated the 5′ terminal nucleotides and identified them as 2′- or 3′-monophosphate guanosine 5′-triphosphate (pppGp) and 2′- or 3′-monophosphate adenosine 5′-triphosphate (pppAp). By comparing the in vitro and in vivo synthesized ΦX174 mRNA, a difference in the pppAp-pppGp ratio was observed. In the in vitro RNA, this ratio was 1.5, whereas in the in vivo RNA it was 5.5.
PMCID: PMC356284  PMID: 4552415
9.  φX-174 Bacteriophage Structural Mutants Which Affect Deoxyribonucleic Acid Synthesis 
Journal of Virology  1969;4(4):400-407.
Seven cistrons in φX-174 were identified and one in particular was studied intensively: cistron A, which is assigned a protein in the mature phage. Amber mutants in this cistron synthesize a new deoxyribonucleic acid (DNA) form in addition to circular phage DNA upon infection of the restrictive host. This DNA is linear, non-infectious, and single-stranded; it is formed from the phage strand of replicative form φX-174 DNA. These mutants produce two different defective particles in the restrictive host. One particle contains circular phage DNA but is not infectious; the other contains the new DNA form and is similar to the 70S particles found in wild-type phage lysates. The mutant A gene product acts independently of normal A protein upon mixed infection of the restrictive host with an A mutant and a mutant from any other cistron or wild type.
PMCID: PMC375888  PMID: 5823229

Results 1-9 (9)