JoAn S. Hudson

Uptake, translocation, and transmission of carbon nanomaterials in rice plants.

Recent development of nanotechnology has reshaped the landscape of modern science and technology, while in the meantime raised concerns about the adverse effects of nanomaterials on biological systems and the environment. Owing to their mutual interaction, carbon-based nanomaterials readily aggregate and are not considered potential contaminants in the liquid phase. However, when discharged into the environment, the hydrophobicity of nanomaterials can be averted through their interaction with natural organic matter (NOM), a heterogeneous mixture of decomposed animals and plants and a major pollutant carrier in nature. Consequently, mobile NOM-modified nanomaterials may pose a threat to ecological terrestrial species through further physical, chemical, and biological processes. The impact of nanomaterials on high plants has scantly been examined in the current literature. Among the studies available, none have used major food crops or carbon nanoparticles (a major class of nanomaterials) for their evaluations. Although both enhanced and inhibited growth have been reported for vegetations exposed to nanomaterials at various developmental stages, including seed germina-

Ultrastructure of the full-term shark yolk sac placenta. I. Morphology and cellular transport at the fetal attachment site.

During ontogeny, the yolk sac of some viviparous sharks differentiates into a yolk sac placenta that persists to term. The placenta is non-invasive and non-deciduate. Hematrophic transport is the major route of nutrient transfer from mother to fetus. The placental unit consists of: (1) an umbilical stalk; (2) the smooth, proximal portion of the placenta; (3) the distal, rugose portion; (4) the egg envelope; and (5) the maternal uterine tissues. Exchange of metabolites is effected through the intervening egg envelope. The distal rugose portion of the placenta is the fetal attachment site. It consists of: (1) surface epithelial cells; (2) a collagenous stroma with vitelline capillaries; and (3) an innermost boundary cell layer. The columnar surface epithelial cells are closely apposed to the inner surface of the egg envelope. Wide spaces occur between the lateral margins of adjacent cells. Surface epithelial cells contain an extensive apical canalicular-tubular system and many whorl-like inclusions in their basal cytoplasm. Capillaries of the vitelline circulation are closely situated to these cells. A well-developed collagenous stroma separates the surface epithelium from an innermost boundary cell layer. In vitro exposure of full-term placentae to solutions of trypan blue and horseradish peroxidase (HRP) reveals little uptake by the smooth portion of the placenta but rapid absorption by the surface epithelial cells of the distal, rugose portion. HRP enters these cells by an extensive apical system of smooth-walled membranous anastomosing canaliculi and tubules. Prominent whorl-like inclusions that occupy the basal cytoplasm of the surface cells, adjacent to the pinocytotically active endothelium of the vitelline capillaries, are hypothesized to be yolk proteins that are transferred from the mother to embryo throughout gestation.

Controlled assembly of rodlike viruses with polymers.

A practical method to assemble rodlike tobacco mosaic virus and bateriophage M13 with polymers was developed, which afforded a 3D core-shell composite with morphological control.

Ultrastructure of the full-term shark yolk sac placenta: III. The maternal attachment site

During mid- and late gestation, the uterus of sandbar sharks possesses specialized sites for exchange of metabolites between the mother and fetus. Attachment sites are highly vascular, rugose elevations of the maternal uterine lining that interdigitate with the fetal placenta. The maternal epithelium remains intact and there is no erosion. The attachment site consists of a simple, low columnar juxtaluminal epithelium underlain by an extensive vascular network. Juxtaluminal epithelial cells possess branched microvilli, saccular invaginations of the apical surface, and coated pits. They contain numerous coated vesicles, lipid-like inclusions, a prominent rough endoplasmic reticulum, and many free ribosomes. Tight junctions join the luminal aspect of adjacent cells. Lateral cell boundaries are highly folded and interdigitated. Capillaries are closely apposed to the basal cell surfaces. The endothelium is pinocytotically active. Comparison with the uterine epithelium of non-placental sharks, mammalian epitheliochorial placentae, and selected transporting epithelia reveals that the structure of the maternal shark placenta is consistent with its putative multiple functions, viz: (1) nutrient transfer; (2) transport of macromolecules, e.g., immunoglobulins; (3) respiration; and (4) osmotic and ionic regulation.

Ultrastructure of the full-term shark yolk sac placenta. II. The smooth, proximal segment.

The smooth, proximal portion of the yolk sac placenta of the sandbar shark, Carcharhinus plumbeus is comprised of: (1) An outermost epithelial ectoderm; (2) an intervening collagenous stroma; and (3) an inner mesothelium. The surface epithelium may be one to three cell layers thick. The surface epithelium comprises two cell types. A cuboidal cell that has a dome-like apical surface covered with microvilli and an ovoid nucleus predominate. These cells contain lipid inclusions, many cytoplasmic filaments, and are joined by desmosomes. The second cell type has a convoluted nucleus and a flattened cell apex with microvilli, cilia, and paddle cilia. Golgi complexes and elements of the endoplasmic reticulum are relatively uncommon in the cytoplasm of both cell types. Microplicae also occur on the surface of some cells. The smooth, proximal portion of the placenta is sparsely vascularized. The innermost cellular elements of the surface epithelium rest on a prominent basal lamina. A collagenous zone separates the epithelial basal lamina from the basal lamina of the mesothelium. The mesothelial cells are squamous with a fusiform nucleus, many pinocytotic pits and vesicles, and a large number of cytoplasmic filaments. The endoplasmic reticulum, except for occasional patches of the rough type, and the Golgi complex are poorly developed. Ultrastructural tracer studies show that this portion of the placenta does not absorb horseradish peroxidase (HRP) and trypan blue.

Evaluation of nanostructured vanadium(V) oxide in catalytic oxidations

Nanostructured V2O5 was prepared by electrochemical anodization in the presence of complex fluoride electrolytes. The reactivity of nanostructured V2O5 was compared to a commercially available V2O5 sample in several oxidation reactions. Catalyst nanostructuring offers improvements in yields as well as rate enhancement in oxidations.