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Full-Text Articles in Life Sciences

Floral Nectary Fine Structure And Development In Glycine Max L. (Fabaceae), Harry T. Horner, Rosaria A. Healy, Teresa Cervantes-Martinez, Reid G. Palmer Sep 2003

Floral Nectary Fine Structure And Development In Glycine Max L. (Fabaceae), Harry T. Horner, Rosaria A. Healy, Teresa Cervantes-Martinez, Reid G. Palmer

Botany Publication and Papers

Floral nectaries of annual cultivated Glycine max develop between the bases of the central gynoecium and lateral stamen ring. Each discoid nectary forms immediately before flower opening and degenerates within 24 h. Three stages of nectary development are identified: preactive, active, and postactive. Preactive and active nectaries are composed of a single-layered epidermis that contains many open stomata, with guard cells having thickened walls, starch-engorged plastids, and other organelles. The major portion of each nectary consists of thin-walled special parenchyma cells, each having dense cytoplasm with a nucleus, Golgi bodies and vesicles, mitochondria, plastids, endoplasmic reticulum, many ribosomes, and one ...


Ascorbic Acid: A Precursor Of Oxalate In Crystal Idioblasts Of Yucca Torreyi In Liquid Root Culture, Harry T. Horner, Albert P. Kausch, Bruce L. Wagner Nov 2000

Ascorbic Acid: A Precursor Of Oxalate In Crystal Idioblasts Of Yucca Torreyi In Liquid Root Culture, Harry T. Horner, Albert P. Kausch, Bruce L. Wagner

Botany Publication and Papers

Liquid-cultured primary roots of Yucca torreyi L. (Agavaceae), which are similar to its intact roots, develop uninterrupted files of calcium oxalate crystal idioblasts with raphide bundles in their cortex, beginning just proximal to the terminal meristem. Each single file of idioblasts displays a basipetal ontogenetic sequence. [1-14C]glycolic acid, [1-14C]glyoxylic acid, and L-[1-14C]ascorbic acid, all of which are potential precursors of oxalate, were each added to different flasks that contained a sterile liquid medium and isolated roots and were allowed to interact with the roots for 45 min. After thorough washing, the roots grew for periods that ...


Genetics And Cytology Of A New Male-Sterile, Female-Fertile Soybean Mutant, H. Ilarslan, Harry T. Horner, R. G. Palmer Jan 1999

Genetics And Cytology Of A New Male-Sterile, Female-Fertile Soybean Mutant, H. Ilarslan, Harry T. Horner, R. G. Palmer

Botany Publication and Papers

Mutants affecting male sterility have potential applications in breeding methodology studies and for commercialization of hybrids. Male-sterile, female-fertile soybean [Glycine max (L.) Merr.] plants were observed in an F2 entry. Our objectives were to determine the inheritance, linkage, and allelism of the A94-JB-124 male-sterile, female-fertile mutant, and to conduct a detailed comparative microscopic study of microsporogenesis and microgametogenesis of fertile and sterile plants. The A94-JB-124 male-sterile, female-fertile mutant is a single recessive gene, allelic to ms6, and is linked to the W1 (flower color locus) with 4.3 ± 0.3% recombination value based on 988 F2 plants in ...


Genetics And Cytology Of A New Genic Male-Sterile Soybean [Glycine Max (L.) Merr.], Wei Jin, Harry T. Horner, Reid G. Palmer Feb 1997

Genetics And Cytology Of A New Genic Male-Sterile Soybean [Glycine Max (L.) Merr.], Wei Jin, Harry T. Horner, Reid G. Palmer

Botany Publication and Papers

Genetic and cytological studies were conducted with a new male-sterile, female-fertile soybean [Glycine max (L.) Merr.] mutant. This mutant was completely male sterile and was inherited as a single-recessive gene. No differences in female or male gamete transmission of the recessive allele were observed between reciprocal cross-pollinations in the F1 or F2 generations. This mutant was not allelic to any previously identified soybean genic male-sterile mutants: ms1, ms2, ms3, ms4, ms5, or ms6. No linkage was detected between sterility and flower color (W1 locus), or between sterility and pubescence color (T1 locus). Light microscopic and cytological observations of microsporogenesis in ...


Structure Of The Cac1 Gene And In Situ Characterization Of Its Expression (The Arabidopsis Thaliana Gene Coding For The Biotin-Containing Subunit Of The Plastidic Acetyl-Coenzyme A Carboxylase), Jinshan Ke, Joong-Kook Choi, Marianne Smith, Harry T. Horner, Basil J. Nikolau, Eve Syrkin Wurtele Feb 1997

Structure Of The Cac1 Gene And In Situ Characterization Of Its Expression (The Arabidopsis Thaliana Gene Coding For The Biotin-Containing Subunit Of The Plastidic Acetyl-Coenzyme A Carboxylase), Jinshan Ke, Joong-Kook Choi, Marianne Smith, Harry T. Horner, Basil J. Nikolau, Eve Syrkin Wurtele

Botany Publication and Papers

The CAC1 gene of Arabidopsis thaliana that codes for the biotin carboxyl-carrier subunit of the heteromeric acetyl-coenzyme A carboxylase was isolated and sequenced. CAC1 is a single-copy gene interrupted by six introns. Subcellular immunogold labeling indicates that the biotin carboxyl-carrier subunit is localized in the stroma of the plastids and chloroplasts. The CAC1 mRNA accumulates throughout developing embryos and ovules of siliques at a time of rapid growth and oil accumulation (7 d after flowering), but is present at much lower levels in wall cells and central septal cells of the silique. Immunolocalization studies show that the pattern of accumulation ...


Cytology And Genetics Of A Tissue Culture-Derived Soybean Genic Male-Sterile, Female-Sterile, H. Ilarslan, H. T. Skorupska, Harry T. Horner, R. G. Palmer Jan 1997

Cytology And Genetics Of A Tissue Culture-Derived Soybean Genic Male-Sterile, Female-Sterile, H. Ilarslan, H. T. Skorupska, Harry T. Horner, R. G. Palmer

Botany Publication and Papers

A completely male-sterile, female-sterile mutant was derived from tissue culture of cv. Calland. The primary goal was to identify its inheritance, allelism, and cytology. Calland sterile (TC) was nonallelic with st2, st3, st4, and st5 female-sterile and malesterile mutants. In all crosses, except st5, single-gene recessive inheritance was documented. Critical ratios, 15 fertile: 1 sterile (for two loci) and 45 fertile: 19 sterile (for three loci), were observed in the F2 families from the cross of heterozygous Calland TC andSt5st5. F3 segregation data confirmed the duplicate factor inheritance of ...


The Effects Of Disturbance Architecture On Landscape-Level Population Dynamics, Kirk A. Moloney, Simon A. Levin Mar 1996

The Effects Of Disturbance Architecture On Landscape-Level Population Dynamics, Kirk A. Moloney, Simon A. Levin

Botany Publication and Papers

Phenomena such as disturbance play a major role in structuring ecological systems by producing a spatiotemporal mosaic of patches at different successional states. The distribution of species within the resulting mosaic depends upon an interaction between species' life history traits and the spatial and temporal structure of the ecological processes controlling species' distributions. We have used a spatially explicit simulation model (Jasper) of a serpentine grassland to examine the importance of some of these relationships, focusing primarily on the role of disturbance. The model Jasper is hierarchical in design and was developed to simulate the population dynamics of three interacting ...


Oak-Leaf-Litter Rhizomorphs From Iowa And Texas: Calcium Oxalate Producers, Harry T. Horner, Lois H. Tiffany, George Knaphus Jan 1995

Oak-Leaf-Litter Rhizomorphs From Iowa And Texas: Calcium Oxalate Producers, Harry T. Horner, Lois H. Tiffany, George Knaphus

Botany Publication and Papers

Unidentified basidiomycete rhizomorphs growing on oak-leaf litter {Quercus alba) in Iowa and in Texas {Quercus gravesii) displayed arrays of crystals associated with their hyphae. X-ray diffraction and birefringence analyses identified the crystals as a mix- ture of calcium oxalate-monohydrate and -dihydrate. The Iowa oak-leaf-litter rhizomorph crystals occurred in two forms: young hyphae displayed either small styloid-like crystals oriented in all directions along the hyphae; or large clusters of elongated styloid-like crys? tals surrounding the hyphae, with individual crystals in each cluster displaying pyramidal ends. Crystals as? sociated with the Texas oak-leaf-litter rhizomorphs consistently covered all of the young hyphae and ...


The Distribution Of Vallisneria Americana Seeds And Seedling Light Requirements In The Upper Mississippi River, Anne Kimber, Carl E. Korschgen, Arnold G. Van Der Valk Jan 1995

The Distribution Of Vallisneria Americana Seeds And Seedling Light Requirements In The Upper Mississippi River, Anne Kimber, Carl E. Korschgen, Arnold G. Van Der Valk

Botany Publication and Papers

Vallisneria americana declined in backwaters of the Upper Mississippi River, U.S.A., after a drought in 1988. To determine whether viable seeds of V. americana occurred in the seed bank of navigation pool 7, Lake Onalaska, the upper 5 cm of sediment was collected from 103 sites in May 1990. These sediment samples were kept in pots at a depth of 0.4, 0.8, and 1.2 m in an outdoor pond for 12 weeks. Vallisneria americana seeds germinated from sites throughout the lake, and some seedlings produced overwintering buds by the end of the study. Seeds, spores ...


Nuclear Size And Dna Content Of The Embryo And Endosperm During Their Initial Stages Of Development In Glycine Max (Fabaceae), Mark A. Chamberlin, Harry T. Horner, Reid G. Palmer Oct 1993

Nuclear Size And Dna Content Of The Embryo And Endosperm During Their Initial Stages Of Development In Glycine Max (Fabaceae), Mark A. Chamberlin, Harry T. Horner, Reid G. Palmer

Botany Publication and Papers

A technique was developed for isolating embryo sacs from ovules of soybean and for separating embryo from endosperm. Image analysis and cytophotometry were used to determine the relative mass of DNA and size of nuclei of endosperm and embryo cells. Analyses were done at the globular through late heart-shaped embryo stages to correlate ploidy level or nuclear size, and differentiation in these tissues. Mean size of embryo nuclei was fairly constant through all stages studied. Ploidy condition of the embryo was stable, 950/o99% of the nuclei were distributed in a bipolar pattern by relative mass at 2C and 4C ...


Nutrition Of Ovule, Embryo Sac, And Young Embryo In Soybean: An Anatomical And Autoradiographic Study, Mark A. Chamberlin, Harry T. Horner, Reid G. Palmer Jan 1993

Nutrition Of Ovule, Embryo Sac, And Young Embryo In Soybean: An Anatomical And Autoradiographic Study, Mark A. Chamberlin, Harry T. Horner, Reid G. Palmer

Botany Publication and Papers

Photosynthesizing soybean plants were exposed to '"0, to study the incorporation of labeled water-insoluble photosynthates in ovules at various developmental stages. Using autoradiographic techniques on sectioned material, we show that the distribution of labeled carbon in different ovular tissues is regulated spatially and temporally. During zygote through globular stages of embryo development, labeled assimilates accumulate in integumentary tissue adjacent to the micropylar and chalazal poles of the embryo sac. A chalazal vascular trace and two adfunicular vascular strands are the pathways for accumulation of I4C in these regions. Up through the proembryo stage, movement of labeled photoassimilates into the lateral ...


Twin Raphides In The Vitaceae And Araceae And A Model For Their Growth, A. M. Cody, Harry T. Horner Sep 1983

Twin Raphides In The Vitaceae And Araceae And A Model For Their Growth, A. M. Cody, Harry T. Horner

Botany Publication and Papers

Several optical tests were employed to demonstrate twinning in raphides from 10 species in the family Vitaceae and one species in the Araceae. Scanning electron microscopy revealed that twin raphides differ from the reported shape of twin styloids and that raphides of the Vitaceae are "barbed" along two sides. A model is proposed to describe in vivo raphide production under saturated to supersaturated conditions of directional nutrient flow.


Formation Of Calcium Oxalate Crystals Associated With Apothecia Of The Discomycete Dasyscypha Capitata, Harry T. Horner, Lois H. Tiffany, Anita M. Cody Jan 1983

Formation Of Calcium Oxalate Crystals Associated With Apothecia Of The Discomycete Dasyscypha Capitata, Harry T. Horner, Lois H. Tiffany, Anita M. Cody

Botany Publication and Papers

Calcium oxalate dihydrate crystals form at or near the tips of sterile hairs on the apothecia of the oak leaf litter discomycete Dasyscypha capitata. Early in their development, the crystals appear to be covered by a wall or membrane, whereas later they appear external. The crystals on each hair form a mass of crystals called a druse. Quite often the smaller crystals near the apex of the tip form a rosette, whereas the more peripheral crystals are much larger and display shapes possibly related to environmental factors. The formation and development of Dasyscypha crystals are compared with recent studies of ...


Succession In Wetlands: A Gleasonian Appraoch, Arnold G. Van Der Valk Jun 1981

Succession In Wetlands: A Gleasonian Appraoch, Arnold G. Van Der Valk

Botany Publication and Papers

A qualitative model of succession in freshwater wetlands is proposed, based on the life history features of the species involved. Three key life history traits can be used to characterize wetland species: life—span, propagule longevity, and propagule establishment requirements. By combining these three life history traits, 12 basic wetland life history types are recognized. For each life history type, the future state (presence only in the form of propagules in the seed bank, presence as adult plants, or complete absence) of each species type in a wetland can be predicted if environmental conditions change. Most of the information needed ...


The Role Of Seed Banks In The Vegetation Dynamics Of Prairie Glacial Marshes, Arnold G. Van Der Valk, C. B. Davis Jan 1978

The Role Of Seed Banks In The Vegetation Dynamics Of Prairie Glacial Marshes, Arnold G. Van Der Valk, C. B. Davis

Botany Publication and Papers

The presence of viable seed in 24 substrate samples from Eagle Lake, a marsh in north—central Iowa, was tested by placing subsamples of each sample under 2 environmental conditions. One set of subsamples was placed underwater (submersed treatment). Seeds of 20 species germinated and grew in this treatment. On the average, there were 8.3 species/sample. The 2nd set of subsamples was kept moist, simulating conditions on an exposed mud flat (drawdown treatment). In the drawdown treatment, on the average, seeds of 12.9 species germinated/sample. Altogether seeds of 40 species germinated in this treatment of which ...


Raphide Crystal Cell Development In Leaves Of Psychotria Punctata (Rubiaceae), Harry T. Horner, R. E. Whitmoyer Jan 1972

Raphide Crystal Cell Development In Leaves Of Psychotria Punctata (Rubiaceae), Harry T. Horner, R. E. Whitmoyer

Botany Publication and Papers

The distribution and development of raphide crystal cells in nodulated leaves of Psychotria punctatawere studied by light and electron microscopy. Crystal cells in the leaf are oriented in various ways depending on whether they occur in the spongy or palisade parenchyma. Crystals are never found within the bacterial nodules and are not concentrated around them. Developing leaf crystal cells become larger than surrounding cells and have larger nuclei and nucleoli. Raphides develop within membrane chambers in the large central vacuole in association with membrane complexes, vesicles and tubules, the latter measuring 10-13 nm in diameter. Certain cytoplasmic organelles, the ...