Polyacrylamide gel electrophoretic analysis of herpes simplex virus type 1 immunoprecipitates obtained by quantitative immunoelectrophoresis in antibody-containing agarose gel.

Crossed immunoelectrophoresis was used to characterize herpes simplex virus type 1 (HSV-1) antigens produced by infected HEp-2 cells. We report on a method for analyzing the polypeptide content in individual antigen-antibody precipitates eluted from the second-dimensional agarose gel. Four glycoprotein antigens of HSV-1, Ag-8, Ag-11, Ag-6, and Ag-3, were isolated and analyzed for polypeptide content. The molecular weights of the polypeptides are presented.     

Deoxyribonucleic acid synthesis and deoxyribonucleic acid-polymerase activity during early germination of wheat embryos at high and low viability

³H-thymidine incorporation and DNA-polymerase activity during early hours of wheat embryo germination at two viability levels have been studied. The patterns of two biosynthetic activities, as well as the dependence of DNA synthesis on protein synthesis, indicated the presence of a delay in the early phase of imbibition of the aged embryos with respect to viable germs.     

Retinol-induced modification of the extracellular matrix of endothelial cells: Its role in growth control

Summary The growth of the endothelial cell (EC) is tightly regulated throughout the body. Many factors have been implicated in modulating EC growth including diffusible compounds, cell-to-cell interactions, and the extracellular matrix (ECM). Retinol, or vitamin A alcohol, has recently been shown to inhibit the growth of bovine capillary ECs, in vitro. Retinoids are known to modify ECM in other cell systems, and pure ECM components have been shown to effect EC growth rates. We, therefore, examined the role of the matrix in the retinol-induced inhibition of ECs. Cell-free matrices from control and vitamin A-treated ECs were prepared by removing cells with EGTA treatment after 7 d of culture. Matrix proteins were analyzed by solubilizing the matrices in 5M quanidine-HCl and performing Western blot analysis using specific antibodies to matrix proteins. In isolating the ECM, we observed that retinol-treated cultures of ECs were resistant to EGTA removal; retinol-treated ECs required twice the exposure time to EGTA to detach from their matrix than did controls cells. Western blot analysis of matrix proteins derived from control and retinol-treated EC cultures demonstrated a 1.6-fold increase in lamininβ chains and a 2.5-fold increase in fibronectin in the ECM of retinol-treated EC compared to control cell matrix. Functional properties of these matrices were assessed by plating control and Day 6 retinol-treated ECs onto the matrices and measuring attachment and growth by determining cell numbers at 24, 72, and 144 h. These studies revealed that control cells attached in greatest numbers to a control matrix whereas retinol-treated ECs preferentially attached to a matrix derived from retinol-treated cells. Furthermore, control ECs which grew rapidly on a control matrix were growth inhibited on a retinol-derived matrix. These data indicate that vitamin A treatment of ECs effects both their phenotype and influences the composition and the functional properties of their underlying ECM. These studies also demonstrate that alterations of the matrix are at least in part responsible for the growth inhibition of EC by retinol.     

An in vitro model for cell-cell interactions

Summary Heterotypic cell-cell interactions appear to be involved in the control of development and function in a wide variety of tissues. In the vasculature, endothelial cells and mural cells (smooth muscle cells or pericytes) make frequent contacts, suggesting a role for intercellular interactions in the regulation of vascular growth and function. We have previously grown endothelial cells and mural cells together in mixed cultures and found that heterocellular contact led to endothelial growth inhibition. However, this mixed culture system does not lend itself to the examination of the effects of contact on the phenotype of the individual cell types. We have therefore developed a co-culture system in which cells can be co-cultured across a porous membrane, permitting intercellular contact while maintaining pure cell populations. Co-culture of endothelial cells and smooth muscle cells across membranes with pore sizes of 0.02, 0.4, 0.6, and 0.8μm maintained the two cell types as homogeneous populations, whereas smooth muscle cells migrated across the membrane through pores of 2.0μm. Vascular cell co-culture across membranes with 0.8-μm pores resulted the inhibition of endothelial cell proliferation and the generation of conditioned media which inhibited endothelial cell growth. The arrangement of the cells in this co-culture system mimics thein vivo orientation of vascular cells in which mural cells are separated from the abluminal surface of the endothelium by a fenestrated internal elastic lamina or basement membrane. Because this co-culture system maintains separable populations of cells in contact or close proximity allowing for biochemical and molecular analyses of pure populations, it should prove useful for the study of cell-cell interactions in a variety of systems.     

Changes in spatial distribution pattern during the larval stage of the fall webworm,Hyphantria cunea drury (Lepidoptera: Arctiidae)

Summary The changes in spatial distribution pattern during larval stage of the fall webworm,Hyphantria cunea were quantitatively investigated in the field experimental populations. The female adult deposits eggs as a cluster and the hatchlings make a compact colonial-web. In this period, the all-or-none type mortality which is characteristic in gregarious insect species was occasionary recognized before spinning a compact colonial-web. Once making a compact colonial-web, the larvae feed the leaves in the colonial-web up to about 5th instar. In this period, the movement of larvae occurred due to the local food shortage in a colonial-web and the expansion of colonial-web. As the larvae developed, the colonial-web was separated into several small groups. These larvae began to disperse about 5th instar. In this period, the local food shortage seems to be an important trigger for the larval dispersal. The mean concentration of larvae on leaves abruptly decreased, and finally the larvae became solitary at the 6th or 7th instars. The dispersal process in later larval stage is not necessarily due to the complete food shortage. The dispersal prior to the occurrence of food shortage may be a safety mechanism to protect the larvae from the food shortage.     

Parrotfish sex ratios recover rapidly in Bermuda following a fishing ban

Parrotfishes are an ecologically and commercially important teleost group whose grazing contributes to maintaining coral-dominated states on hermatypic reefs. However, overfishing has skewed sex ratios of Atlantic parrotfishes because fishing has disproportionate impacts on larger individuals, and males are generally larger than females. Whether protection from fishing may allow sex ratios to return to equilibrium is unknown, as fishing can induce irreversible ecological and/or evolutionary shifts. Bermuda banned trap fishing in 1990, creating a unique opportunity to analyse long-term responses of Atlantic parrotfishes to release from fishing. We found that sex ratios of four common parrotfishes were initially skewed, with male proportions ranging from 0.04 to 0.18. However, male proportions rebounded within 3–4 yr, equilibrating at values ranging from 0.36 to 0.54, similar to those reported at unfished sites in the region. Our results are encouraging for regional efforts to recover lost grazing function by restoring overfished herbivore populations.