Effect of vanadate and ouabain on insulin binding and insulin imprinting in Tetrahymena.

Na-metavanadate and ouabain that act on Na+K(+)-ATPase had no influence on insulin binding to Tetrahymena immediately after treatment, but after 24 h considerably enhanced the binding capacity of generations of progeny. The increase in binding was of a similar magnitude to that elicited by insulin imprinting. Vanadate failed to increase the imprinting potential of insulin while ouabain even prevented insulin imprinting when administered together with insulin, but, did not affect imprinting when administered after insulin. By analogy with higher organisms it appears that inhibition of Na+K(+)-ATPase plays no role in the insulin-like effect of vanadate on the unicellular Tetrahymena, as judged also from the capacity to bind insulin of the generations of offspring.     

Effect of insulin imprinting on the 3H-amino acid uptake of the Tetrahymena

Insulin imprinting given to the unicellular Tetrahymena considerably increases the uptake and intracellular storage of amino acids even many generations after the actual contact with the hormone. On the other hand, both the first and the second contacts with insulin increase the rate of the excretion of the stored amino acids. On the basis of the results obtained it seems to be possible that both protein synthesis and exocytosis of the Tetrahymena change as an effect of imprinting, either in general or specifically due to the formation of new hormone receptors.     

Overlapping imprinting of oligopeptides in Chang liver cells. Data on the mechanism of hormone evolution

Imprinting was induced with synthetic oligopeptides in Chang liver cell cultures to test these molecules for signal molecule value. Investigations into imprinting overlaps (cross-imprinting) have shown that all oligopeptides (di-, tetra- and pentapeptides) carrying a terminal proline group were able to imprint the cells for the pentapeptide Tyr-D-Met-Gly-Phe-Pro-NH2, which displayed an outstanding imprinting potential for itself and an extraordinary opioid activity as well. The fact that exclusively the proline-deficient oligopeptide (a tetrapeptide) failed to imprint for the pentapeptide in question, indicates a decisive role of proline in the transformation of molecules to signal carriers (hormones). The pentapeptide in question did imprint for the related molecules (except the dipeptide) but to a much lesser degree than for itself. The marked inferiority of the pentapeptide's cross-imprinting potential to its self-imprinting potential supports the hypothetical implication that a considerable difference between the specific and non-specific binding capacities of a molecule, if not the loss of non-specific binding was an essential prerequisite of transformation to a signal molecule, i.e. of hormone evolution.     

Effect of inhibitors and activators of tyrosine kinase on insulin imprinting in Tetrahymena.

Primary exposure of Tetrahymena cells to insulin gave rise to hormonal (insulin) imprinting in the offspring generations, as judged from the increase in binding upon reexposure to insulin. Vanadate mimicked the action of insulin, inasmuch as it also induced imprinting for insulin, whereas the other tyrosine kinase activator tested, namely H2O2, had no such effect. However, combined treatment with vanadate+H2O2 + insulin induced a more pronounced imprinting for insulin than either insulin or vanadate on their own. The tyrosine kinase inhibitor genistein, a plant flavonoid, did not change the value for insulin binding significantly relative to the control immediately after exposure, but increased it slightly in the offspring generations after 24 h at high dilution. Upon combination with insulin, 10(-4)M genistein inhibited imprinting by insulin. These experimental observations suggest that there may be a key role for tyrosine kinase activity in the mechanism (development) of imprinting.     

Tetrahymena actin: localization and possible biological roles of actin in Tetrahymena cells

Though actin is ubiquitous in eukaryotes, its existence has not been clearly proven in Tetrahymena. Recently, we have succeeded in cloning and sequencing the Tetrahymena actin gene using a Dictyostelium actin probe (Hirono, M. et al. (1987) J. Mol. Biol. 194, 181-192). The primary structure of the Tetrahymena actin deduced from the nucleotide sequence of its gene is greatly divergent from those of other known actins, making it necessary to ascertain whether the predicted Tetrahymena actin is indeed an actin. In this paper, we investigated the localization of the predicted Tetrahymena actin by an immunofluorescence technique using antibody against its synthetic N-terminal peptide, in order to elucidate its possible biological roles. The results showed that immunofluorescence was localized in the division furrow of the dividing cell, and in the intranuclear filament bundles formed in cells exposed to heat shock or DMSO. In addition, the oral apparatus and the proximity of the cytoproct, which are organelles involved in endocytosis and exocytosis, respectively, also fluoresced. Thus, we conclude that the Tetrahymena actin we identified is indeed an actin and plays the same biological roles as ubiquitous actins do, although it is considerably divergent in its amino acid sequence.     

Synthesis and biological studies of glycosyl dopamine derivatives as potential antiparkinsonian agents

A new approach to deliver dopamine into the central nervous system, based on the use of D-glucose as transportable agent, has been studied. Glycosyl dopamine derivatives bearing the sugar moiety linked to either the amino group or the catechol ring of dopamine through amide, ester or glycosidic bonds were synthesised as potential antiparkinsonian agents. Studies on the binding to dopamine D2 receptor, in vitro stability, and locomotive effect in mice of the synthetic glycoconjugates are reported.     

Hormone evolution studies: multiplication promoting and imprinting ("memory") effects of various amino acids on Tetrahymena

Aromatic, heterocyclic, polar and non-polar amino acids were examined for imprinting potential in a unicellular (Tetrahymena) model system. Serine gave rise to positive, glycine to negative imprinting, whereas valine, tryptophan, tyrosine and phenylalanine had no imprinting effect whatever. However, tyrosine and phenylalanine stimulated the division of Tetrahymena already at primary interaction, the former even for a relatively long time. It follows that amino acids, too, can give rise to imprinting, although their imprinting potentials are dissimilar. These phenomena have attracted attention to possible interrelationships between the supposed amino acid receptors of Tetrahymena and the evolution of amino acids to hormones.     

Coumarin derivatives as potential inhibitors of acetylcholinesterase: Synthesis,molecular docking and biological studies

A series of novel hybrids has been synthesized by linking coumarin moiety through an appropriate spacer to various substituted heterocyclic amines and evaluated as dual binding site acetylcholinesterase inhibitors for the treatment of cognitive dysfunction caused by increased hydrolysis of acetylcholine and scopolamine induced oxidative stress. Anti-amnesic activity of the compounds was evaluated using Morris water maze model at a dose of 1 mg/kg with reference to the standard, donepezil. Biochemical estimation of oxidative stress markers (lipid peroxidation, superoxide dismutase, and plasma nitrite) was carried out to assess the antioxidant potential of the synthesized molecules. Among all the synthesized compounds (15a–i, 16a–d, 17a–b), compound 15a [4-[3-(4-phenylpiperazin-1-yl)propoxy]-2H-chromen-2-one] displayed significant antiamnesic activity, AChE inhibitory activity (IC₅₀ = 2.42 μM) and antioxidant activity in comparison to donepezil (IC₅₀ = 1.82 μM). Molecular docking study of 15a indicated that it interacts with all the crucial amino acids present at the CAS, mid-gorge and PAS of TcAChE resulting in increased inhibition of AChE enzyme.     

Growth effects on the insulin alteration of Chang liver fatty acid metabolism

The effect of insulin on the free fatty acid metabolism of Chang liver cells was observed to vary, depending on the growth rates of the cells. When the cells were not actively growing, insulin modestly increased the total recovery of radioactive fatty acid in lipid and produced a major increment of fatty acid in cellular triglyceride. During logarithmic growth of the cells these insulin changes were much less pronounced.     

Effect of the cAMP level on hormonal imprinting in Tetrahymena

Augmentation of the cAMP level has no positive effect on hormonal imprinting in Tetrahymena. Artificial elevation of the cAMP level may inhibit the development of imprinting or may result in abnormal imprinting. The role of Ca2+ is of great importance in mediation of the imprinting mechanism. Generally, this role is not influenced by an elevated cAMP level but, exceptionally, the latter may effect the mechanism of imprinting.     

Synthesis of naphthalimide derivatives with potential anticancer activity,their comparative ds- and G-quadruplex-DNA binding studies and related biological activities

Molecular Biology Reports - Two new cytotoxic 1,8-naphthalimide derivatives have been synthesized and characterized. Their biological activities as cytotoxicity and antimicrobial activities and...     

Influence of deciliation and ciliary regeneration on hormonal imprinting in Tetrahymena. Observations on the 'localization' of imprinting

Imprinting induced in Tetrahymena with insulin is not abolished by deciliation. No imprinting occurred in deciliated cells exposed to insulin at 1 or 2 h of regeneration. However, imprinting did occur if Tetrahymena was exposed to insulin after 3 h of regeneration. It appears that while presence of cilia is a prerequisite of imprinting, the pertinent information is not, or not exclusively stored in the cilia.     

Impact of serum concentration of the medium and fasting on the imprintability of the insulin receptors of Chang liver cells.

When the cells of the Chang cell line came into interaction with a hormone (insulin) an imprinting-like phenomenon took place. The binding capacity of the receptors strengthened and this feature was transmitted to the descendant generations. The quality of the nutrient medium influenced the development of imprinting, when the cells were maintained in a medium containing 2% serum it was more difficult to evoke imprinting than in case the cells were kept in a medium containing 10% serum. If the cells were cultured kept in Tyrode (physiological) solution for 24 hours the possibility to evoke imprinting was lost. Difference could be observed between the behaviour of receptors in nuclear membrane and that of receptors in the plasma membrane; i.e. changes were more dynamic in the plasma membrane.     

Insulin uptake, localization and production in previously insulin treated and untreated Tetrahymena. Data on the mechanism of hormonal imprinting

Confocal microscopic experiments demonstrate the presence of insulin in Tetrahymena, observed also in earlier experiments. However, there is a broad spectrum of insulin-containing cells from the immunocytochemically insulin-free, to the strongly antibody-reactive ones. During 1 h of insulin treatment (imprinting) the cells gradually bind and take up insulin, and the process is slow. One minute after the start of treatment there is not difference in the number of insulin antibody-reactive cells and amount of insulin. After 5 or 10 min the cells bind and contain more insulin and after 1 h most of the cells are densely packed with the insulin antibody-reactive material. Insulin imprinting accelerates binding and uptake alike: 48 h after imprinting and 1 min after the start of the second treatment, more insulin is present on the surface and inside the cells, than after 10 min in the first-time treated cells. Theoretically, this effect of hormonal imprinting helps to maintain the species by facilitating molecular recognition and binding as well as uptake of useful molecules. The experiments also support previous observations on the parallel receptor-evoking (strengthening) and hormone-producing effect of hormonal imprinting.