Effect of colchicine on polymerization of tubulin from rats,mice, hamsters and guinea-pigs

Summary Colchicine-inhibition of polymerization of tubulin from rats, mice, golden hamsters and guinea-pigs was studied to determine if species differences in tubulin sensitivity to colchicine might parallel species variation in colchicine toxicity. It was found that polymerization of tubulin is nearly equally sensitive to colchicine in all four species.This work was supported by PHS Grant No. CA 16425.     

Colchicine inhibition of ADH effect on frog skin permeability

ADH and AMPc enhance both thiourea unidirectional fluxes in frog skin. This effect is completely abolished by colchicine pretreatment. The ADH increase of thiourea discharge with or without colchicine led us to suppose that colchicine does not directly affect ADH action on outer membrane permeability, but exerts its effects on a site which is limiting for the ADH action on transepithelial permeability.     

Effect of colchicine on polymerization of tubulin from rats, mice, hamsters and guinea-pigs.

Colchicine-inhibition of polymerization of tulbulin from rats, mice, golden hamsters and guinea-pigs was studied to determine if species differences in tubulin sensitivity to colchicine might parallel species variation in colchicine toxicity. It was found that polymerization of tubulin is nearly equally sensitive to colchicine in all four species.     

Colchicine inhibition of ADH effect on frog skin permeability

Summary ADH and AMPc enhance both thiourea unidirectional fluxes in frog skin. This effect is completely abolished by colchicine pretreatment. The ADH increase of thiourea discharge with or without colchicine led us to suppose that colchicine does not directly affect ADH action on outer membrane permeability, but exerts its effects on a site which is limiting for the ADH action on transepithelial permeability.The present work has been supported by C.N.R., Rome.     

New patterns of vascular development in roots of Pisum recovering from colchicine treatment

Summary Abnormal vascular patterns were formed in pea roots recovering from a 3-h treatment with 0.025% of colchicine solution. New, often asymmetrical, patterns arose by the formation of additional protoxylem poles; later the patterns converted to a normal symmetrical tetrarch or triarch condition.Acknowledgment. I. thank Professor L. W. Roberts, University of Idaho, for the help he gave me during the preparation of this paper.     

Colchicine induced interchanges in chillies (Capsicum annuum L.)

Summary Seeds ofCapsicum annuum L. cultivar cerasiformies were treated with 0.4 and 0.2% aqueous colchicine solution for 24 and 72 h respectively. Tetraploids were not realized; instead, interchange heterozygosity was observed in several plants in 0.4% treatment. The interchanges varied from 1 to 3 per plant. It is presumed that colchicine has induced chromosome breaks.     

Is tubulin involved in the electrically-induced mechanical activity of the isolated rat sciatic nerve?

Summary The electrically-induced mechanical activity of isolated segments of rat sciatic nerves remains unaffected following incubation with 10^–4 M colchicine, vinblastine or melatonin. Vinblastine depressed tubulin levels in incubated nerves. These results suggest that microtubules are not involved in nerve mechanical activity in vitro.This work was supported by grant No. 6638 from the CONICET (Argentina). It is dedicated to the memory of C.E. Valenti, decreased November 1979.     

Molecular and Cellular Basis of Regeneration and Tissue Repair

Nymphs of hemimetabolous insects such as cockroaches and crickets exhibit a remarkable capacity for regenerating complex structures from damaged legs. Until recent years, however, approaches to elucidate the molecular mechanisms underlying the leg regeneration process have been lacking. Taking the cricket Gryllus bimaculatus as a model, we found that a phenotype related to regeneration frequently appears during leg regeneration, even though no phenotype is induced by RNA interference (RNAi) in the cricket nymph, designated as regeneration-dependent RNAi. Since then, we have investigated the functions of various genes encoding signaling factors and cellular adhesion proteins like Fat and Dachsous during leg regeneration. In this review, we summarize the classical knowledge about insect leg regeneration and introduce recent advances concerning the signaling cascades required for regenerating a leg. Our results provide clues to the mechanisms of regeneration which are relevant to vertebrate systems.     

Comparison of the in vitro effects of colchicine and its derivative colchiceine on chondrocyte morphology and function

Summary Colchiceine is a colchicine-metabolite which has been reported to inhibit axonal transport although not binding to brain tubulin. In the present study, colchiceine was shown not to depolymerize cytoplasmic microtubules, nor to mimic other effects of colchicine on the ultrastructure of cultured chondrocytes. In addition, the synthesis of proteoglycans was inhibited by colchicine but slightly stimulated by colchiceine. These results support the idea that the disturbances in cultured chondrocytes caused by colchicine are specifically related to a loss of cytoplasmic microtubules.This work was supported by grants from the Swedish Medical Research Council (proj. No. 12X-03355), the King Gustaf V 80th Birthday Fund, the Swedish Society of Medical Sciences, and from the funds of Karolinska Institutet.     

A stereoscan analysis of cell surface characteristics during the interkinetic nuclear migration in normal and colchicine-treated developing chick retina

Summary The cell surface and shape changes taking place during the interkinetic nuclear migration are reported in normal neuroepithelial cells of chick retina, and after metaphase-arrest induced by colchicine. Persistence of the apical junctions and loss of basal connections during the preparation for mitosis have been demonstrated in these cells.     

Melatonin antagonizes colchicine-induced mitotic arrest.

Melatonin, in concentrations up to 10(-3) M, showed no effect on mitosis in cultures of HeLa or KB cells. However, when melatonin at 10(-4) M was preincubated with HeLa cells prior to addition of 10(-7) M colchicine, a reduction in the mitotic index, in comparison to colchicine alone, was observed.     

Comparison of the in vitro effects of colchicine and its derivative colchiceine on chondrocyte morphology and function

Colchiceine is a colchicine-metabolite which has been reported to inhibit axonal transport although not binding to brain tubulin. In the present study, colchiceine was shown not to depolymerize cytoplasmic microtubules, nor to mimic other effects of colchicine on the ultrastructure of cultured chondrocytes. In addition, the synthesis of proteoglycans was inhibited by colchicine but slightly stimulated by colchiceine. These results support the idea that the disturbances in cultured chondrocytes caused by colchicine are specifically related to a loss of cytoplasmic microtubules.     

Molecular and engineering approaches to regenerate and repair teeth in mammals

Continuous replacement of teeth throughout the lifespan of an individual is possibly basal for most of the vertebrates including fish and reptiles; however, mammals generally have a limited capacity of tooth renewal. The ability to induce cellular differentiation in adults to replace lost or damaged cells in mammals, or to tissue-engineer organs in vitro, has hence become one of the major goals of regenerative medicine. In this article, we will revisit some of the important signals and tissue interactions that regulate mammalian tooth development, and will offer a synopsis of the latest progress in tooth regeneration and repair via molecular and engineering approaches. It is hoped that this article will not only offer an overview of recent technologies in tooth regeneration and repair but will also stimulate more interdisciplinary research in this field to turn the pursuit of tooth regeneration and repair into practical reality.     

Melatonin antagonizes colchicine-induced mitotic arrest

Summary Melatonin, in concentrations up to 10^–3 M, showed no effect on mitosis in cultures of HeLa or KB cells. However, when melatonin at 10^–4 M was preincubated with HeLa cells prior to addition of 10^–7 M colchicine, a reduction in the mitotic index, in comparison to colchicine alone, was observed.This work was supported by PHS Grant No. CA 16425.     

Coating of centrospheres by reticulum cisternae and formation of spindle residues in segmentation mitosis under the action of an antitubulin substance: nocodazole]

When cleaving eggs are treated by nocodazole the reticulum cisternae coat the centrospheres instead of the chromosomes, as normally occurs at the late anaphase. At the same time the spindle is reduced to a common mass or spindle remnant, constituted of unorientated and fragmented microtubules which embed the kinetochores, i. e. the star configuration of the chromosomes. This action is quite similar to that of chloralhydrate but is different from that of colchicine.     

Somatostatin inhibits the mitogenic effect of thyroliberin

Summary The effect of somatostatin and of thyroliberin on the mitotic incidence in the organ-cultured anterior pituitary lobe of the rat was investigated, using the colchicine metaphase-arrest technique. It was found that somatostatin added to the culture medium, together with thyroliberin, blocked the mitogenic effect of the latter.This work was supported by Polish Academy of Sciences, program No 10. 4.     

Transmembrane potential of J774.2 mouse macrophage cells measured by microelectrode and ion distribution methods

The transmembrane potential (Em) of J774.2 macrophage cells measured by microelectrodes was -24.1 +/- 0.7 mV (mean +/- SEM). Em measured by lipophilic ion distribution was -35 +/- 2 mV or -40 +/- 2 mV, using a cation or anion, respectively. By any method, colchicine reduced Em by approximately 3 mV.     

Hh signaling in regeneration of the ischemic heart

Myocardial infarction (MI) is caused by the occlusion of a coronary artery due to underlying atherosclerosis complicated by localized thrombosis. The blockage of blood flow leads to cardiomyocyte (CM) death in the infarcted area. Adult mammalian cardiomyocytes have little capacity to proliferate in response to injury; however, some pathways active during embryogenesis and silent during adult life are recruited in response to tissue injury. One such example is hedgehog (Hh) signaling. Hh is involved in the embryonic development of the heart and coronary vascular system. Pathological conditions including ischemia activate Hh signaling in adult tissues. This review highlights the involvement of Hh signaling in ischemic tissue regeneration with a particular emphasis on heart regeneration and discusses its potential role as a therapeutic agent.     

Somatostatin inhibits the mitogenic effect of thyroliberin.

The effect of somatostatin and of thyroliberin on the mitotic incidence in the organ-cultured anterior pituitary lobe of the rat was investigated, using the colchicine metaphase-arrest technique. It was found that somatostatin added to the culture medium, together with thyroliberin, blocked the mitogenic effect of the latter.     

Response of murine spermatocytes to the metaphase-arresting effect of several mitotic arrestants

Summary Three mitotic arrestants, colchicine, Colcemid and vinblastine, were evaluated for their effects on producing meiotic arrest in the laboratory mouse. Colchicine is the most effective and its effect is both dose- and time-dependent. Treatment of mice with 40 mg/kg of colchicine for 3 h resulted in drastic improvement of the yield and quality of M-II figures. This treatment did not appear to increase the aneuploidy frequency in M-II's.Supported in part by research grant R-808582 from the US Environmental Protection Agency and research grant RR5511-21 from the National Institute of Health.