Immunochemical and immunohistochemical detection of S-100-like immunoreactivity in spinach tissues.

Abstract

S-100 proteins represent a group of closely related acidic, calcium binding proteins originally isolated from the mammalian nervous system and later detected in non-neural cell types and in a wide variety of vertebrate and invertebrate species. The present study used immunochemical and immunohistochemical methods to extend the investigation of S-100 during phylogenesis to plant tissues. The presence of S-100-like immunoreactive material was detected in extracts of spinach (Spinacia oleracea L.) terminal buds and young leaves by the ELISA method and by Western blotting using different anti-S-100 rabbit antisera. Using the PAP method, serial sections of young spinach leaves treated with the same antisera exhibited an immunoreaction product that was confined to the cytoplasm and nucleus (but absent from the vacuoles) in meristematic, epidermal, and parenchymal cells. The present data enlarge the field of investigation of S-100 proteins in the search of the function(s) of S-100 in biological organisms.

Perinatal S100B Protein Assessment in Human Unconventional Biological Fluids: A Minireview and New Perspectives

“…The hypothesis of assessing the protein in a so complex biological fluid was based on the following elements: (i) S100 proteins are highly conserved in amino acid composition among vertebrate species, suggesting a pivotal, although still unknown, biological role for the protein [40]; (ii) S100-like proteins have also been immunologically detected in spinach leaves suggesting a potential role in human food-chain [41], adipose tissue also constitutes a site of concentration for the protein [42]; (iii) breast milk is known to contain growth factors and cytokines [43–46]; (iv) milk is abundant in other calcium-binding proteins (e.g., alpha-lactalbumin, calmodulin, osteocalcin) [47–49]. Results showed S100B in human breast milk; in addition, S100B milk content was estimated to be 80/100 times higher than those detected in CSF, blood, urine [50].…”