Biomedical subjects

J F Chabot

Publications and source records attributed to J F Chabot.

8 recordsLinked to original sources

PubMed1982

Effects of Light and Nutrients on Leaf Size, CO(2) Exchange, and Anatomy in Wild Strawberry (Fragaria virginiana).

Plants of a single genotype of wild strawberry, Fragaria virginiana Duchesne, were grown with or without fertilizer in high (406 microeinsteins per square meter per second) and low (80 microeinsteins per square meter per second) light. High-light leaves were thicker than low-light leaves and had greater development of the mesophyll. Within a light level, high-nutrient leaves were thicker, but the proportions of leaf tissues did not change with nutrient level. Maximum net CO(2) exchange rate and leaf size were greatest in high-light, high-nutrient leaves and lowest in high-light, low-nutrient leaves. Changes in mesophyll cell volume largely accounted for differences in CO(2) exchange rate in low-light leaves, but not in high-light leaves.Leaf size in these experiments was apparently determined by nutrient and carbon supply. This may explain the observation that the largest leaves produced by wild strawberries in the field occur in high-light, mesic habitats, rather than in shady habitats.

Journal Article↗

PubMed1979

Ontogeny of Photosynthetic Performance in Fragaria virginiana under Changing Light Regimes.

Apparent photosynthesis and dark respiration were followed during development in four light environments of leaves of Fragaria virginiana Duchesne. Leaf expansion was completed more rapidly the higher the growth photon flux density and leaves senesced more quickly in high light. Maximum photosynthetic capacity coincided with the completion of blade expansion and declined quickly thereafter. Leaves were transferred from high to low and low to high photon flux densities at several stages during expansion. Leaf photosynthetic performance and anatomy were subsequently analyzed. Leaf anatomy and apparent photosynthesis per unit dry weight can be modified during expansion to reflect the predominant light conditions. Adaptive potential is greatest early in blade expansion and decreases as expansion is completed.

Journal Article↗

PubMed1976

Renal neoplastic response to leukosis virus strains BAI A (avian myeloblastosis virus) and MC29.

Previous reports described the induction of avian renal neoplasms by leukosis virus strains BAI A [avian myeloblastosis virus (AMV)] and MC29, and illustrated morphological characteristics of the tumors. Continued studies in this work confirm evidence of the origin of the tumors from embryonal cells residual in the posthatched chick. The work further emphasizes differences in histopathology of the neoplasms caused by the two viruses and reveals differences in the histopathogenesis of the respective growths. Embryonal rests may consist of two types of cells, those of epithelial characteristics and a second element of differentiation between nephroblastema (mesenchyme) and epithelium and designated here as nephromesoblastoma. Infection by AMV induces tumors of epithelial characteristics and, in addition, derivatives of nephromesoblastoma consisting of cartilage, bone, areas of keratinization, and sarcoma. Keratinized structures in the nephroblastoma originate from nephromesoblastoma. In contrast, MC29 virus induces only epithelial growths representing principally aberrant and malformed glomerular and tubular structures with occasional cartilage derived from epithelial cells. MC29 tumors are completely lacking in nephromesoblastoma tissue and contain no bone, sarcoma, or keratinized formations. In MC29 tumors, occasional cartilage was derived from epithelium. Tumors caused by AMV exhibit the complex structure of nephroblastoma with all of the features of the growth in humans (Wilms' tumor). The neoplasms induced by both AMV and MC29 exhibit marked aberration, distortion, and malformation in the differentiation of the cells growing out from the embryonal rests representing rare manifestations of cell genetic influence inherent in the primordial growth of nephroblastema. The results thus illustrate fundamental differences in cellular composition and capacity to respond to etiologically different leukosis viruses.

Adenocarcinoma↗

PubMed1974