Search Results - (Author, Cooperation:R. Shoemaker)

2018-07-31

American Chemical Society (ACS)

Chemistry and Pharmacology

2011-05-13

Nature Publishing Group (NPG)

0028-0836

1476-4687

Biology

Chemistry and Pharmacology

Medicine

Natural Sciences in General

Physics

AIDS Vaccines/immunology ; Animals ; CD4-Positive T-Lymphocytes/immunology ; CD8-Positive T-Lymphocytes/immunology ; Cytomegalovirus/genetics ; DNA, Viral/analysis ; Genetic Vectors/genetics ; Immunity, Mucosal/immunology ; Immunologic Memory/*immunology ; Macaca mulatta/blood/immunology/virology ; Male ; RNA, Viral/analysis ; SAIDS Vaccines/genetics/*immunology ; Simian Acquired Immunodeficiency Syndrome/blood/*immunology/*prevention & ; control/virology ; Simian Immunodeficiency Virus/growth & development/*immunology/isolation & ; purification/*pathogenicity ; T-Lymphocytes/*immunology ; Time Factors ; Vaccines, DNA/genetics/immunology ; Viral Load ; Virus Replication

2013-09-13

Nature Publishing Group (NPG)

0028-0836

1476-4687

Biology

Chemistry and Pharmacology

Medicine

Natural Sciences in General

Physics

Animals ; Cytomegalovirus/genetics/immunology ; Female ; Macaca mulatta ; Male ; Molecular Sequence Data ; SAIDS Vaccines/*immunology ; Simian Acquired Immunodeficiency Syndrome/*prevention & control/virology ; Simian Immunodeficiency Virus/*immunology ; Time Factors ; Vaccines, Attenuated/immunology ; Viral Load ; Virus Replication/physiology

1089-7550

AIP Digital Archive

Physics

Crystalline films of La0.65Pb0.35MnO3 grown on Si (100) substrates by rf sputtering have been investigated by ferromagnetic resonance and MOKE. The dependence of the ferromagnetic resonance line parameters on the sample orientation and temperature is investigated. An expression for the angular dependence of the resonance field on the orientation of the sample is proposed, based on the assumption that close to the Curie temperature the Zeeman and demagnetizing terms are dominant. MOKE data support this hypothesis. The temperature dependence of the magnetization at saturation, in relative units, estimated from ferromagnetic resonance agrees with SQUID data. © 2000 American Institute of Physics.

Electronic Resource

0005-2728

Elsevier Journal Backfiles on ScienceDirect 1907 - 2002

Biology

Chemistry and Pharmacology

Medicine

Physics

Electronic Resource

0040-4039

Elsevier Journal Backfiles on ScienceDirect 1907 - 2002

Chemistry and Pharmacology

Electronic Resource

0742-6046

Psychology

Economics

Special Issue: Coupons

1432-203X

Gossypium hirsutum ; Somatic embryos ; Regeneration ; Morphogenesis ; Genotype

Springer Online Journal Archives 1860-2000

Biology

Summary Seventeen cultivars of cotton (Gossypium hirsutum L.) were evaluated for callus initiation and maintenance using 3 initiation media and 3 maintenance media. After a series of transfers of a 3% glucose media, calli were placed on a 3% sucrose medium. After several weeks calli were observed for the presence of embryo-like structures. Cultivars Coker 201 and Coker 315 were identified as embryogenic. Embryogenic callus has since been routinely obtained within 6 weeks by initiating callus on glucose media for 3–4 weeks followed by transfer to sucrose media. Histological examination has shown that embryos are derived from isodiametric, densely cytoplasmic cells and follow predictable patterns of development. Upon maturity, transfer to auxin-free media with reduced sucrose levels results in embryo germination. Regenerated plants can be transferred to greenhouse within 90 days of callus initiation.

Electronic Resource

1432-203X

Springer Online Journal Archives 1860-2000

Biology

Abstract The effects of spermidine, pH, ethylene diamine tetracetic acid (EDTA), and adenosine triphosphate (ATP) on deoxyribonuclease (DNase) activity associated with the chloroplasts of soybean (Glycine max (L.) Merr.) were investigated. Chloroplast DNase activity was found to be partially inhibited by either 10 mM spermidine, 20 mM EDTA, or 20 mM ATP. DNase activity was also partially inhibited at non-neutral pH's. Nearly complete inhibition was achieved with use of 30 mM EDTA, pH 10, or a combination of 10 mM spermidine and 10 mM EDTA.

Electronic Resource

1573-5028

mitochondrial DNA ; soybean ; recombination ; DNA repeat

Springer Online Journal Archives 1860-2000

Biology

Abstract Mitochondrial (mt) genome organization in soybean was examined at the molecular level. This study builds upon previous reports that four soybean cytoplasmic groups, Bedford, Arksoy, Lincoln, and soja-forage, are differentiated by polymorphisms detected with a 2.3 kb Hind III mtDNA probe [12]. The variation detected results from DNA alterations in a region within and around a 4.8 kb repeat. The Bedford-type cytoplasm is the only cytoplasm that contains copies of a 4.8 kb repeat in four different genomic environments, evidence that it is recombinationally active. The Lincoln- and Arksoy-type cytoplasms each contain two copies of the repeat, as well as unique fragments that appear to result from rare recombination events outside, but near, the repeat. The soja-forage-type cytoplasm contains no complete copies of the repeat, but does contain a unique truncated version of the repeat. Sequence analysis indicates that the truncation is a result of recombination across a 9 bp repeated sequence, CCCCTCCCC. The structural rearrangements that have occurred in the region surrounding the 4.8 kb repeat may provide a means to dissect species relationships and evolution within the subgenus soja.

Electronic Resource

1432-203X

Cotton ; Gossypium hirsutum L. ; Somatic embryogenesis ; storage proteins

Springer Online Journal Archives 1860-2000

Biology

Summary The storage protein content of somatic embryos of Gossypium hirsutum L. cv. Coker 201 was determined using extinction level, antigen/antibody association detection methods. Mature storage protein was first detected in early globular-stage somatic embryos at a total concentration of 0.36% of the embryo protein mass. Tulip-stage and mature somatic embryos were comprised of 3.0% and 1.3% mature storage protein, respectively. Maximum storage protein synthesis was found to occur during early globular- and early heart-stages. During this period of development, significant levels of protein precursors were found also to accumulate. The pattern of storage protein synthesis, processing and accumulation paralleled the pattern that has been reported for the zygotic system, although somatic embryos accumulate storage protein at much earlier stages and to a lesser degree. The possibility of using complex biochemical pathways to monitor embryogenic systems in vitro is discussed.

Electronic Resource

1432-1424

Springer Online Journal Archives 1860-2000

Biology

Chemistry and Pharmacology

Summary Necturus fundic gastric mucosa was studied to define the magnitude of cellular and shunt conductance. Electrotonic coupling of surface epithelial cells by a low resistance pathway was shown by analysis of current spread within the epithelial sheet. From this analysis cellular conductance was found to be 4.18 ± 1.57 × 10−4 Ω−1 cm−2, and transepithelial shunt conductance was 1.1 × 10−4 Ω−1 cm−2. The ratio of cell-to-shunt conductance was 3.80. These results are confirmed by a second technique in which the Δp. d. across the serosal membrane of surface cells was compared to the transepithelial Δp. d. resulting from a Δ[K+] in the serosal solution. The data were analyzed using an electrical circuit equivalent to a mucosa composed of two highly coupled cell types. By this technique cell conductance was 3.07 × 10−4 Ω−1 cm−2, and transepithelial shunt conductance was 0.830 × 10−4 Ω−1 cm−2. The cell/shunt conductance ratio was 3.70. Thus, by two independent techniques the transepithelial shunt contributes only 1/5 of the conductance ofNecturus fundic gastric mucosa.

Electronic Resource

1432-2242

Nuclear-cytoplasmic interaction ; Chlorophyll ; Glycine max L. ; Maternal inheritance ; Plastid ultrastructure

Springer Online Journal Archives 1860-2000

Biology

Summary Genetic analysis of a yellow foliar mutant in soybean (Glycine max L. Merr.) showed maternal inheritance of the mutant phenotype designatedcyt-Y 3. The mutant was grown beside normal green sibs (cyt-G 3) under three different photosynthetic photon flux densities (PPFD), and samples were collected to determine pigment content and for electron microscopy analyses of plastid ultrastructure. The plastid ultrastructure ofcyt-Y 3 appeared normal at low PPFD and the carotenoid level ofcyt-Y 3 was also normal, but the chlorophyll content was only approximately one-third that ofcyt-G 3. Under medium and high PPFD,cyt-Y 3 plastids lacked a structured thylakoid, and total chlorophyll content was only 28% and 1% of normal, respectively; the carotenoid levels ofcyt-Y 3 also dropped to 33% and 2% of normal, respectively. These data indicate that the effect of high PPFD oncyt-Y 3 might result from a deficiency in a plastid membrane protein. The resulting changes in membrane configuration could then interfere with the accumulation or stabilization of chlorophylls and carotenoids, thereby resulting in the subsequent photooxidation of both at medium and high PPFD. This mutant could be useful in the study of thylakoid biosynthesis and pigment stabilization, or could provide a source of conditionally identifiable plastids for organelle segregation studies.

Electronic Resource

1432-2242

Glycine max ; Glycine tomentella ; Chromosome elimination ; Isoenzyme variation

Springer Online Journal Archives 1860-2000

Biology

Summary A colchicine-doubled F1 hybrid (2n=118) of a cross between PI 360841 (Glycine max) (2n=40) x PI 378708 (G. tomentella) (2n=78), propagated by shoot cuttings since January 1984, produced approximately 100 F2 seed during October 1988. One-fourth of the F2 plants or their F3 progeny have been analyzed for chromosome number, pollen viability, pubescence tip morphology, seed coat color, and isoenzyme variation. Without exception, all plants evaluated possessed the chromosome number of the G. max parent (2n=40). Most F2 plants demonstrated a high level of fertility, although 2 of 24 plants had low pollen viability and had large numbers of fleshy pods. One F2 plant possessed sharp pubescence tip morphology, whereas all others were blunt-tipped. All evaluated F2 and F3 plants expressed the malate dehydrogenase and diaphorase isoenzyme patterns of the G. max parent and the endopeptidase isoenzyme pattern of the G. tomentella parent. Mobility variants were observed among progeny for the isoenzymes phosphoglucomutase, aconitase, and phosphoglucoisomerase. This study suggests that the G. Tomentella chromosome complement has been eliminated after genetic exchange and/or modification has taken place between the genomes.

Electronic Resource

1432-2242

Glycine max ; Phytophthora sojae resistance ; Restriction fragment length polymorphism (RFLP) ; Gene tagging ; Marker-assisted breeding

Springer Online Journal Archives 1860-2000

Biology

Abstract The Phytophthora root and stem resistance locus Rps1 has been mapped to linkage group N of the USDA-ARS soybean molecular map, approximately 2 cM from locus A071-1. To determine if A071-1 polymorphisms exist that distinguish and tag different Rps1 alleles, germplasms containing the seven Rps1 alleles were screened with eight enzymes for pA071-detectable polymorphisms. Six enzymes revealed at least one polymorphic fragment. All six detected a polymorphism at A071-1 as determined by restriction fragment length polymorphism mapping, comparison to an EMBL3 clone containing locus A071-1, and Southern hybridization with probes specific for locus A071-1. Screening of the Rps1 donors and 24 Rps1-and 15 Rps1-containing U.S. soybean varieties showed that locus A071-1 exhibited three polymorphisms with each enzyme. The polymorphisms detected by one enyme did not always correlate with those detected by the other four, suggesting that multiple mutation events may be responsible for the different A071-1 polymorphisms. Although no combination of alleles distinguished Rps1-and Rps1-containing genotypes, polymorphism at A071-1 made it possible to distinguish five groups of soybean germplasms. Thus, the unusual polymorphism of locus A071-1 should useful for following Rps1 inheritance in many breeding programs.

Electronic Resource

1432-2242

Key words Bacterial artificial chromosome ; Simple sequence repeats ; Microsatellites ; Soybean cyst nematode ; Genetic mapping

Springer Online Journal Archives 1860-2000

Biology

Abstract  Simple sequence repeats (SSRs) are versatile DNA markers that are readily assayed and highly informative. Unfortunately, non-targeted approaches to SSR development often leave large genomic regions without SSR markers. In some cases these same genomic regions are already populated by other types of DNA markers, especially restriction fragment length polymorphisms (RFLPs), random amplified polymorphic DNAs (RAPDs), and amplified fragment length polymorphisms (AFLPs). To identify SSR markers in such regions, bacterial artificial chromosome (BAC) clones can be used as intermediaries. First, one or more BAC clones in a region of interest are identified through the use of an existing DNA marker. BAC clones uncovered in this initial step are then used to create a small insert DNA library that can be screened for the presence of SSR-containing clones. Because BAC inserts are often 100-kb pairs or more in size, most contain one or more SSRs. This strategy was applied to two regions of the soybean genome near genes that condition resistance to the soybean cyst nematode on molecular linkage groups G and A2. This targeted approach to identifying new DNA markers can readily be extended to other types of DNA markers, including single nucleotide polymorphisms.

Electronic Resource

1432-2242

Key words Soybean  ;  Cultivar development  ;  Recombination  ;  Molecular markers

Springer Online Journal Archives 1860-2000

Biology

Abstract An analysis of the genome structure of soybean cultivars was conducted to determine if cultivars are composed of large regions of chromosomes inherited intact from one parent (indicative of minimal recombination) or if the chromosomes are a mixture of one parent’s DNA interspersed with the DNA from the other parent (indicative of maximal recombination). Twenty-one single-cross-derived and 5 single-backcross-derived soybean cultivars and their immediate parents (47 genotypes) were analyzed at 89 RFLP loci to determine the minimal number and distribution of recombination events detected. Cultivars derived from single-cross and single-backcross breeding programs showed an average of 5.2 and 8.0 recombination events per cultivar, respectively. A homogeneity Chi-square test based upon a Poisson distribution of recombination events across 13 linkage groups indicated that the number of recombinations observed among linkage groups was random for the single-cross cultivars, but not for the single-backcross-derived cultivars. A two-tailed t-test demonstrated that for some linkage groups, the number of recombinations per map unit exceeded the confidence interval developed from a t-distribution of recombinations standardized for map unit distance. Paired t-tests of the number of recombinations observed between linkage-group ends and the mid-portion of the linkage groups indicated that during the development of the cultivars analyzed in this study more recombinations were associated with the ends of linkage groups than with the middle region. Detailed analysis of each linkage group revealed that large portions of linkage groups D, F, and G were inherited intact from one parent in several cultivars. A portion of linkage group G, in contrast, showed more recombination events than expected, based on genetic distance. These analyses suggest that breeders may have selected against recombination events where agronomically favorable combinations of alleles are present in one parent, and for recombination in areas where agronomically favorable combinations of alleles are not present in either parent.

Electronic Resource

1432-2242

Key words Em-like gene family ; Soybean ; Cloning ; Characterization ; Mapping

Springer Online Journal Archives 1860-2000

Biology

Abstract  The entire Em-like Group-1 late embryogenesis abundant (Lea) gene family from soybean was cloned and characterized. The five Group-1 Lea genes (Sle1-5) were divided into two classes based on sequence identity. Sle1-4 were genetically mapped to four different linkage groups. Nucleotide sequencing indicated that Sle1, Sle2, Sle3, and Sle5 encode polypeptides differing primarily by the presence of a repeated 20-amino acid motif. Sle1 and Sle5 were shown by Northern analysis to be expressed in developing embryos weeks earlier than Sle2 and Sle3. Sle4 was shown to be a pseudogene. Maximal levels of mRNA for all functional Sle genes accumulated in maturation-phase seeds, before significant desiccation had occurred, and declined rapidly upon seed imbibition. Desiccation did not induce Sle expression in seeds or vegetative tissue. Sle expression was confined to embryo tissues and Sle mRNA accumulated at similar levels in both the embryo axis and in the cotyledons.

Electronic Resource

1432-2242

Soybean ; RFLP ; Quantitative trait loci ; Germination ; Hard seededness

Springer Online Journal Archives 1860-2000

Biology

Summary Hard seededness in soybean [Glycine max (L.) Merr.] is a quantitative trait that affects the germination rate, viability, and quality of stored seeds. We have used 72 restriction fragment length polymorphisms (RFLPs) to identify genomic regions containing quantitative trait loci (QTL) affecting hard seededness in a segregating population from a G. max by a Glycine soja (Sieb. & Zucc.) cross. Five independent RFLP markers were found to be associated with variation in the hard-seeded trait. These markers and the epistatic interactions between them explain 71% of the variation for hard seededness. A genomic region associated with the i locus accounted for 32% of the variation in this segregating population. This study illustrates one approach to physiological genetic studies in plants.

Electronic Resource

1432-2242

Soybean ; Cultivar development ; Recombination ; Molecular markers

Springer Online Journal Archives 1860-2000

Biology

Abstract An analysis of the genome structure of soybean cultivars was conducted to determine if cultivars are composed of large regions of chromosomes inherited intact from one parent (indicative of minimal recombination) or if the chromosomes are a mixture of one parent's DNA interspersed with the DNA from the other parent (indicative of maximal recombination). Twenty-one single-cross-derived and 5 single-backcross-derived soybean cultivars and their immediate parents (47 genotypes) were analyzed at 89 RFLP loci to determine the minimal number and distribution of recombination events detected. Cultivars derived from single-cross and single-backcross breeding programs showed an average of 5.2 and 8.0 recombination events per cultivar, respectively. A homogeneity Chi-square test based upon a Poisson distribution of recombination events across 13 linkage groups indicated that the number of recombinations observed among linkage groups was random for the single-cross cultivars, but not for the single-backcross-derived cultivars. A twotailed t-test demonstrated that for some linkage groups, the number of recombinations per map unit exceeded the confidence interval developed from a t-distribution of recombinations standardized for map unit distance. Paired t-tests of the number of recombinations observed between linkage-group ends and the mid-portion of the linkage groups indicated that during the development of the cultivars analyzed in this study more recombinations were associated with the ends of linkage groups than with the middle region. Detailed analysis of each linkage group revealed that large portions of linkage groups D, F, and G were inherited intact from one parent in several cultivars. A portion of linkage group G, in contrast, showed more recombination events than expected, based on genetic distance. These analyses suggest that breeders may have selected against recombination events where agronomically favorable combinations of alleles are present in one parent, and for recombination in areas where agronomically favorable combinations of alleles are not present in either parent.

Electronic Resource