Recent studies have demonstrated the fundamental role of cell-substrate contacts and changes in cell shape in the regulation of cell growth, motility and differentiation, but the molecular basis for these phenomena is poorly understood. Because of the involvement of cytoskeletal networks in cell morphogenesis and contact formation, it is of interest that the expression of genes encoding several cytoskeletal proteins is markedly affected by changes in cell contacts and configuration. Because most of these phenomena involve changes in the form, extent or topology of cell contacts, we sought to determine whether the expression of components directly involved in the formation of cell-cell or cell-substrate contacts is affected by the respective cellular interactions. A suitable candidate for such analysis is vinculin, a cytoskeletal protein of relative molecular mass (Mr) 130,000 (130K), which is localized in focal contacts and intercellular adherens junctions. The assembly of vinculin into a membrane-bound junctional plaque seems to be one of the earliest cellular responses to contact with exogenous substrates, leading to the subsequent local assembly of the actin-rich microfilament bundles. Here we report on the regulation of vinculin synthesis in response to environmental conditions that affect cell shape and contacts.

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PubMedDate not supplied

Chronobiologic lead study cost-effectively assesses circadian-circaseptan intermodulation in murine pineal melatonin content.

The investment into the design of a study is usually and unfortunately proportional to the available information, i.e. the less one knows the more one is tempted to skimp and perform a minimal 'pilot' study. This is particularly true with respect to chronobiology. On the contrary, at the outset of a study, when the information available regarding a given problem is minimal or zero, the investment into a first study should be near-maximal. Accordingly, the often wasted 'pilot study' should be replaced by a rigorous chronobiologic lead study. The promise of such a chronobiologic 'guide, leading along a difficult or unknown course' is illustrated by the validation with statistical significance of an about-weekly (circaseptan) and an about 24-h (circadian) rhythm in the melatonin content of the murine pineal. Work around the clock on 48 female Lewis/S rats was avoided. Replication of 6 different circadian times on different comparable animals on consecutive days assessed a circaseptan rhythm more prominent than the concomitantly demonstrated circadian, at no added cost for experimental animals beyond those often used for circadian study and with no work around the clock.

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PubMedDate not supplied

More on the circadian melatonin rhythm in pineals from domesticated B6D2F1 mice.

For melatonin (a chronomodulator of adrenal cortical function, immune phenomena and carcinogenesis), a circadian rhythm is demonstrated in aqueous pineal homogenate of domesticated B6D2F1 mice. Domestication as such does not eliminate a mechanism of cephalo-adrenal coordination.

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