Distribution of Cytoskeletal Components in Endothelial Cells in the Guinea Pig Renal Artery

The cytoskeletal components of endothelial cells in the renal artery were examined by analysis of en face preparations under confocal laser scanning microscopy. Renal arterial endothelial cells were shown to be elongated along the direction of blood flow, while stress fibers ran perpendicular to the flow in the basal portion. Focal adhesions were observed along the stress fibers in dot-like configurations. On the other hand, stress fibers in the apical portion of cells ran along the direction of flow. The localizations of stress fibers and focal adhesions in endothelial cells in the renal artery differed from those of unperturbed aortic and venous endothelial cells. Tyrosine-phosphorylated proteins were mainly detected at the sites of cell-to-cell apposition, but not in focal adhesions. Pulsatile pressure and fluid shear stress applied over endothelial cells in the renal artery induce stress fiber organization and localization of focal adhesions. These observations suggest that the morphological alignment of endothelial cells along the direction of blood flow and the organization of cytoskeletal components are independently regulated

Recent Progress on the Effects of Weaning and Nutrition on the Action of Physiologically Active Peptides in the Ruminant

In the present mini-review, we will introduce our recent new findings accumulated at the Animal Physiology Laboratory over the last several years, in particular with reference to studies on leptin and ghrelin, which are involved in both the control of the somatotropic axis (GHRH/GHS-GH-IGF-I system) and in the regulation of the energy balance of domestic animals. Our interest is also focused on weaning because it is the most drastic event that neonates have to experience through their lives. 1) We compared the effect of feeding on basal plasma GH levels in 3-(milk-fed) and 12-week old (concentrates and roughage-fed) Holstein bull calves, and found that feeding caused a rise in GH levels at 3 weeks but a reduction at 12 weeks of age. 2) Plasma leptin levels, which were increased with aging in Japanese Black cattle, were not changed during the 5 hours after feeding. However, the expression of leptin, and CCK_A and CCK_B receptors in the stomachs of calves was abolished after weaning. This finding was confirmed even when calves were maintained on a milk replacer diet with an intragastric injection of VFA until 13 weeks of age. In addition, we demonstrated that VFA increased the expression of leptin, but suppressed that of the leptin receptor (OB-Ra) in calf anterior pituitary cells. 3) Although the basal ghrelin level in the plasma of goats decreases as the animal ages, parallel with basal GH levels as well as the responses of GH to GH secretagogues, milk feeding appears not to reduce the basal ghrelin levels in calves and goats. Weaning significantly decreased the ghrelin content to 30% of that seen pre-weaning in the stomachs. These findings will substantially contribute to the studies on the control of the somatotropic axis and the regulation of the energy balance of ruminant animals

Microwave-Assisted Tissue Preparation for Rapid Fixation, Decalcification, Antigen Retrieval, Cryosectioning, and Immunostaining

Microwave irradiation of tissue during fixation and subsequent histochemical staining procedures significantly reduces the time required for incubation in fixation and staining solutions. Minimizing the incubation time in fixative reduces disruption of tissue morphology, and reducing the incubation time in staining solution or antibody solution decreases nonspecific labeling. Reduction of incubation time in staining solution also decreases the level of background noise. Microwave-assisted tissue preparation is applicable for tissue fixation, decalcification of bone tissues, treatment of adipose tissues, antigen retrieval, and other special staining of tissues. Microwave-assisted tissue fixation and staining are useful tools for histological analyses. This review describes the protocols using microwave irradiation for several essential procedures in histochemical studies, and these techniques are applicable to other protocols for tissue fixation and immunostaining in the field of cell biology