Betty L. Black

Development of glucose active transport in embryonic chick intestine. Influence of thyroxine and hydrocortisone

1. Glucose active transport is detectable in 12-day-old embryonic chick duodenum and increases at least 11-fold after 4 days of postnatal life. 2. Glucose active transport develops at the in vivo rate in 72-hr cultures of 14-day embryonic duodenum. 3. In the presence of either 1 nM thyroxine or 1 microM hydrocortisone in vitro, glucose active transport reaches levels approximately 200% of control values (equivalent to 18-19 day levels in vivo). 4. Thyroxine and hydrocortisone act by different mechanisms based on their antagonistic interaction and differences in time course of action, requirement for protein synthesis and modulation by extracellular calcium.

Developmental Profile of Claudin‐3, ‐5, and ‐16 Proteins in the Epithelium of Chick Intestine

Proteins in the claudin family are a main component of tight junctions and form a seal that modulates paracellular transport in intestinal epithelium. This research tests the hypothesis that claudins 3, 5, and 16 will appear in the epithelium of embryonic intestine during functional differentiation. Immunohistochemistry is utilized to explore the developmental patterns of claudin‐3, ‐5, and ‐16 proteins in the epithelium of embryonic chick intestine from 9 days prior to hatching through the early post‐hatch period. These claudin proteins either changed their cellular localization or first appeared around the time of hatching. After hatching, claudin‐3 expression was prominent in basal–lateral regions of the epithelium along the entire villus, but was absent from crypts. Claudin‐5 was expressed most strongly in the crypt and lower villus epithelium within junctional complexes, whereas immunostaining of claudin‐16 was localized within goblet cells of the upper villus region. The relative mRNA levels of claudin‐3, ‐5, and ‐16 showed similar patterns; transcript levels rose between 18 and 20 days of development, then dropped by 2 days post‐hatch. Results of this work indicate that the claudin proteins assume their final locations within the epithelium around the time of hatching, suggesting that in addition to their known barrier and fence functions within tight junctions, these claudins may have additional roles in the differentiation and/or physiological function of chick intestine. The localization of claudin‐16 to goblet cells and its distribution in the more mature cells of the upper villus region suggest an unexpected role in goblet cell maturation and mucus secretion. Anat Rec 293:1175–1183, 2010.

Age-related changes in jejunal glucose absorption in mice

Abstract Jejunal glucose absorption was determined in male mice aged 1, 2, 6, 12, and 18 months of age. Active and passive glucose transport was measured in vitro by estimating the uptake of 3-0-methyl-D-glucose by 1 mm jejunal rings in the presence and absence of phlorizin over a 5 min period. Passive glucose transport was found to be constant with increasing age. Active transport peaked at 2 months of age and the steadily declined. The reduction in active glucose transport rate between 2 and 18 months of age was approximately 50%. No corresponding changes were noted for jejunal villus or crypt dimensions, thickness of the jejunal musculature, or mucosal water and protein content. The age-related decrease in absorption is initiated before attainment of mature body weight. These results demonstrate that age specifically modifies active transport function in mouse jejunal mucosa without concomitant alterations in the structure of the jejunal wall.

Preparation of microvillus membrane vesicles from the intestine of embryonic and young chicks

1. A procedure is described for the isolation of microvillus membranes from 19-day old embryonic, newly hatched, and 2-day old chicken intestine. 2. The magnesium concentration of epithelial cell homogenates is shown to be a crucial factor in obtaining membranes of equal purity from the three age groups. 3. Microvillus membranes are purified 20-25 fold over the original homogenate and form vesicles which are tightly sealed based on the Na+-dependent accumulation of glucose to levels four to five times equilibrium values. 4. These membrane preparations should prove useful in future studies concerning the embryonic and neonatal development of microvillus enzymes and nutrient transport systems in the chicken.

The Use of Panoramic Interactive Videography as a Teaching Instrument in High School and University Biology Courses and in Environmental Public Education

We created several interactive learning objects that illustrate organisms within their natural habitats by linking videos to “hotspots” within panoramic vistas of the habitat; students can access these at will and in whatever order they choose. By linking other vistas to hotspots within the primary panorama, the student can take a virtual field trip, examining different views of that habitat, and bringing up moving images of wildlife inhabiting the area. These customizable interactive teaching instruments are provided free of charge to educators who can modify them in whatever way they wish to suit their individual needs and to adapt them to the level of their students. They were designed in accordance with the needs expressed by teachers and were found to be effective as teaching instruments.