High Concentrations Of Colchicine Research Articles

Agro-Morphological Traits and Molecular Diversity of Proso Millet (Panicum miliaceum L.) Affected by Various Colchicine Treatments

Colchicine is a substance used to induce mutations in order to regulate important agronomic traits. The genotypes Pavlodarskoe 4, Quartet, and PI 289324, originating from Kazakhstan, the Russian Federation, and Hungary, respectively, were used as materials. The objective of this study was to investigate the effects of different colchicine concentrations (0.0, 0.04, 0.06, 0.08, and 0.1%) and treatment times (6, 12, and 24 h) on the agronomic traits of proso millet (Panicum miliaceum L.) and to assess the genetic diversity of the M2 generation using inter simple sequence repeat (ISSR) markers. The experiment was conducted in 2021 for the M1 generation and in 2022 for the M2 generation, from May to September. The percentage of field germination decreased with increasing colchicine concentrations and exposure durations. The mean field germination percentages were 48.57% in Pavlodarskoe 4, 43.28% in Quartet, and 53.14% in PI 289324 under colchicine treatment. Chlorophyll-defective M1-M2 plants were obtained using various colchicine concentrations and exposure periods. The highest number of mutational modifications was attained with the 0.08–0.1% concentrations of colchicine. Based on the research results, a total of 248 plants with chlorophyll-defective mutations were selected from 2214 plants. The growing seasons of M1 and M2 plants were shortened by higher colchicine concentrations (0.08–0.1%) combined with soaking times of 12 and 24 h. Thus, the longest growing season (84 days) was observed with a 6 h treatment time for PI 289324, while the shortest (78 days) was recorded for 12 and 24 h treatments. The possibility of obtaining morphological mutations using colchicine has been confirmed. The ISSR primers amplified a total of 1333 fragments; 1281 bands were found to be polymorphic, and 52 bands were monomorphic. The percentage of polymorphism varied from 80 to 100%, with an average of 96.11%. Most of the different allelic bands were detected when applying the 0.08% colchicine concentration. These positive variations are a great opportunity to use colchicine as a tool for improving agronomic traits in plant breeding.

Seed Germination and Seedling Growth of Dendrocalumus brandisii in vitro, and the Inhibitory Mechanism of Colchicine.

Bamboos seldom bloom and almost no seeds could be harvested, and, hence, few works are focused on germination physiology. Systematic research on the physiological effects of colchicine on germination and seedling growth of bamboo seeds is lacking. In this study, we finely recorded seed germination and seedling growth of Dendrocalamus brandisii in media supplemented with different colchicine concentrations. Physiological effects and mechanisms of colchicine were analyzed. The results showed that D. brandisii seeds were non-dormant, and seed lots achieved their highest germination rates on the 4th day and finished the whole germination period after 21 days. Colchicine inhibited seed germination and seedling growth but did not change its germination pattern. Seed germination and seedling growth decreased constantly with colchicine concentration. Colchicine showed more negative effects on seedling growth than on seed germination and root growth. High concentrations of colchicine retarded the development of plumules and even caused their aberrant development. Under tissue culture conditions, seed germination, and seedling growth relied mainly on the endogenous starch and soluble sugar degradation, in which α-amylase, STP, and SUSY played the key role. Colchicine inhibited seed germination and seedling growth by suppressing the α-amylase, STP, and SUSY activities. Colchicine showed more negative effects on sucrose degradation than on starch degradation during seed germination and seedling growth. This study provides new basic information on the seedling physiology for the genetic breeding of bamboo plants.

Colchicine inhibits ROS generation in response to glycoprotein VI stimulation

Colchicine inhibits coronary and cerebrovascular events in patients with coronary artery disease (CAD), and although known to have anti-inflammatory properties, its mechanisms of action are incompletely understood. In this study, we investigated the effects of colchicine on platelet activation with a particular focus on its effects on activation via the collagen glycoprotein (GP)VI receptor, P2Y12 receptor, and procoagulant platelet formation. Therapeutic concentrations of colchicine in vitro (equivalent to plasma levels) significantly decreased platelet aggregation in whole blood and in platelet rich plasma in response to collagen (multiplate aggregometry) and reduced reactive oxygen species (ROS) generation (H2DCF-DA, flow cytometry) in response to GPVI stimulation with collagen related peptide-XL (CRP-XL, GPVI specific agonist). Other platelet activation pathways including P-selectin expression, GPIIb/IIIa conformational change and procoagulant platelet formation (GSAO+/CD62P+) (flow cytometry) were inhibited with higher concentrations of colchicine known to inhibit microtubule depolymerization. Pathway specific mechanisms of action of colchicine on platelets, including modulation of the GPVI receptor pathway at low concentrations, may contribute to its protective role in CAD.

Toxicity and Sublethal Effects of Autumn Crocus (Colchicum autumnale) Bulb Powder on Red Imported Fire Ants (Solenopsis invicta).

Autumn crocus (Colchicum autumnale L.) is a medicinal plant as it contains high concentrations of colchicine. In this study, we reported that the ground powder of autumn crocus bulb is highly toxic to invasive Solenopsis invicta Buren, commonly referred to as red imported fire ants (RIFAs). Ants fed with sugar water containing 5000 mg/L of bulb powder showed 54.67% mortality in three days compared to 45.33% mortality when fed with sugar water containing 50 mg/L of colchicine. Additionally, the effects of short-term feeding with sugar water containing 1 mg/L of colchicine and 100 mg/L of autumn crocus bulb powder were evaluated for RIFAs’ colony weight, food consumption, and aggressiveness, i.e., aggregation, grasping ability, and walking speed. After 15 days of feeding, the cumulative colony weight loss reached 44.63% and 58.73% due to the sublethal concentrations of colchicine and autumn crocus bulb powder, respectively. The consumption of sugar water and mealworm (Tenebrio molitor L.) was substantially reduced. The aggregation rates decreased 48.67% and 34.67%, grasping rates were reduced to 38.67% and 16.67%, and walking speed decreased 1.13 cm/s and 0.67 cm/s as a result of the feeding of the two sublethal concentrations of colchicine and autumn crocus bulb powder, respectively. Our results for the first time show that powder derived from autumn crocus bulbs could potentially be a botanical pesticide for controlling RIFAs, and application of such a product could be ecologically benign due to its rapid biodegradation in the environment.

Induction of Polyploidy in C35 Citrange through in Vitro Colchicine Treatments of Seed-Derived Explants

ABSTRACT Polyploidy can be observed in citrus species which often enables better adaptation to environmental stresses. In this context, this paper aimed to develop stable tetraploid C35 citrange by in vitro colchicine treatments. Seed-derived explants were obtained by a germination experiment using several concentrations of GA3. Culturing seeds of C35 without seed coat on MT basal medium with the addition of 4 mg l−1 GA3 resulted in the highest germination rate (84%). Various colchicine concentrations and exposure time were tested to induce polyploidization. Seed-derived explants of C35 citrange treated with 0.1% colchicine for 48 h demonstrated high rates of mutation for polyploidization and the highest tetraploid induction percentage (15%) was determined in this treatment. Higher colchicine concentrations and exposure time decreased the survival rates of the seedlings. Flow cytometry demonstrated that the nuclear genome size of tetraploids (1.598 pg/2 C) was significantly (P < .01) higher than diploid (0.794 pg/2 C) C35 seedlings. Recovered seedlings were identified with morphological and cytological variables, such as leaf area and stomata size. Generally, leaf area and stomata size significantly increased with the increasing ploidy level. The method used in this present study was relevant and an effective way to induce polyploidy in C35 citrange.

The Effect Of Colchicine on Phenotypes And Stomata Pakcoy (Brassica Rapa L) Hydroponically With The NFT (Nutrient Film Technique) System

Colchicine (C22H25O6N) is a toxic alkaloid compound that causing a polyploidy in the plants, so it produces a robust individuals. The aims of this research are to know the effect of kolchhisin against phenotypes and stomata pakcoy (Brassica rapa L) hydroponically with the NFT (Nutrient Film Technique) system. This research used experimental method with a complete random design (CRD), five treatments and five replications. The data were analyzed by using ANAVA with 5% of credibility. The sample of this research were used pakcoy red arrow F1 nauli with colchicine P0 (Control), P1 (250 mg / L), P2 (500 mg / L), P3 (750 mg / L), P4 (1000 mg / L). The result of this study showed that the influence of colchisin against phenotype and the stomata’s size of pakcoy plant (Brassica rapa L). The high concentrations of colchicine can caused the size of the phenotype (leaves’ number, leaf area, wet weight, dry weight) pakcoy smaller than the control. While the size of the stomata increased, the largest of stomata size was found in the P3 treatment (750 mg / L).

Influence of Colchicine Treatment on Morphological, Physiological and Anatomical Cercis siliquastrum L. Seedlings Growth تأثیر معاملة الکولشیسین على النمووالصفات المظهریة و الفسیولوجبة و التشریحیة لشتلات الأرغوان

The present study was conducted to assess the effect of polyploidy induction on different properties of Cercis siliquastrum plant. Experiment was conducted in RCBD with 15 treatments and 3 replications. The seeds were treated with 0.0, 0.5, 1.0, 1.5 and 2.0 % colchicine solution at room temperature for various exposure times 12, 24 and 48 h. Observations on morphological variations were recorded on each plant in each treatment. Various in seed germination, morphological and growth characteristics observed due to effects of interactions between colchicine concentration and soaked period. By increasing of the colchicine concentration the seed germination rate decreased significantly from 80% to 50%, the effects on seed germinate were most evident at the higher colchicine concentrations (1.5 to 2.0 %). Longer stem and root, thicker stem and root diameter, higher number of leaves, branch and roots per transplant, were width area, thick and greener leaves, variable anatomy wood stem were achieved and development as compared to control plants. The length and width of stomata (21.6 and 10.3µm) respectively were significantly increased and induced in 0.1% of colchicine for 48h, whereas stomata density was decreased to 68 per area in 0.2% of colchicine at 48h. in contrast with initial diploid plants. However 1.5 % and 0.2% concentrations of colchicine at different soaked time were more effective for producing variation in plants. These polyploids plants may be helpful for further development and improvement of ornamental tree.

Influence of exogenous polyamines and plant growth regulators on high frequency in vitro mass propagation of Gloriosa superba L. and its colchicine content

Abstract An efficient in vitro mass propagation technique was successfully developed for Gloriosa superba L. using callus induced from non-dormant corm buds. Sulfuric acid treatment was optimized to break seed dormancy which resulted in high frequency germination. Proficient callus induction and proliferation was observed when the explants were grown on modified MS (mMS) medium supplemented with 2,4-D (1.5 mg l−1) and Kin (1.0 mg l−1). The combination of BA (1.5 mg l−1) and NAA (0.6 mg l−1) induced highest multiple shoot formation frequency. When the medium was supplemented with putrescine (15 mg l−1) the explants responded with highest multiplication frequencies of in vitro shoots. The regenerated shoots showed superlative response for in vitro rooting on mMS medium fortified with IBA (1.0 mg l−1), IAA (0.6 mg l−1) and 15% coconut water. Colchicine content of both field grown and in vitro raised plants were compared using HPLC and it was found that leaf samples from field grown plants showed 0.00241 mg/ml colchicine compared to methanolic extract from Spermidine, Spermine and Putrescine treated leaf samples which showed relatively higher concentrations of colchicine (0.00265 mg/ml, 0.00356 mg/ml and 0.00569 mg/ml) respectively. Putrescine treated in vitro plants showed only a marginal increase in colchicine content compared to spermine and spermidine treated plants. This established protocol will help in both pharmaceutical and conservation aspects of G. superba to meet its commercial demands in the future.

INDUCED MUTAGENESIS IN CULTURE OF ISOLATED TISSUES OF SAINTPAULIA

The paper studied the effects of colchicine on isolated tissue regenerative capacity of violet saintpaulia (Blue Dragon). We determined the optimal dose of the mutagen exposure time and to preserve cell viability and maximize the number of plants regenerated with modified genotype. We used leave fragments (5 × 5 mm) for cell lines. Isolated leaf explants were cultured on MS medium supplemented with benzylaminopurine (BAP) and α-naphthaleneacetic acid at a concentration of 3 and 4 uM respectively. As used chemical mutagen colchicine at concentrations of 10, 50, 80 and 100 mg / l. Colchicine treatment were carried out at three exposures (3, 5 and 10 days), after which the callus tissue was transferred to fresh medium without colchicine for further cultivation. Served as controls on the cultivation medium without colchicine result of the impact of high concentrations of colchicine and duration of exposure to the media explant with a mutagen is the process of callus formation, which underwent surviving meristematic cells. In tissue culture to move into specialized tissue divisible state is always necessary hormonal factors. Probably, in our case, was an inducer such colchicine at concentrations of 50 and 80 mg / l at 10 days exposure. On media II-10 and III-10 callus level ranged from 60 to 100%. When the concentration of colchicine 50 and 80 mg / L and 10 days of exposure there is a low level of direct regeneration and a high percentage of callus formation. Therefore, we can expect changes in the genome of regenerated plants obtained on a medium II-10 and III-10.

POLYPLOID INDUCTION OF DENDROBIUM DRACONIS RCHB.F

This study was carried out to find the optimal conditions for in vitro polyploid induction of Dendrobium draconis Rchb.f. Seed-derived protocorms of D. draconis were transferred to Murashige and Skoog (MS) medium containing different concentrations of colchicine (0-0.1%, in v/v) and maintained in the dark for 1, 2, 3 or 4 days at 25±2°C. The results showed that prolonged exposure (4 days) of the protocorms to high concentrations of colchicine (0.1%) produced a substantial reduction in their survival percentage and shoot regeneration capacity. Three-day exposure of the protocorms to 0.05% colchicine was most effective in polyploid induction. Only tetraploids were achieved, as suggested by squash technique. Levels of polyploidy induced in D. draconis were confirmed by DNA content and flow cytometry. The obtained polyploid plants had thicker, dark green leaves with larger guard cells when compared to diploid plants. The number of guard cells per unit area observed for the polyploid plants produced is however lower than that found in diploid plants, which might be due to the increase in the size of the guard cells.

Production of Colchicine-induced Autotetraploids in Pummelo (Citrus grandis Osbeck) through Indirect Organogenesis

Colchicine-induced stable autotetraploid plants were recovered through indirect organogenesis from stem sections of in vitro-grown zygotic seedlings of pink/red-fleshed pummelo (Citrus grandis L. Osbeck) selections cybrid Hirado Buntan (C-HBP) (pink), 5-1-99-3 (dark pink), and HBJL-5 (red), all derived from Hirado Buntan pink pummelo. Multiple shoot induction was achieved through indirect organogenesis from the callus produced from the cut ends of the treated explants. Ploidy levels of regenerated plantlets were determined through flow cytometry at a stage when recovered shoots had one to two expanded leaves. Recovered tetraploids proved to be stable after 2 years in the field. As expected, higher colchicine concentrations and treatment durations decreased the survival rates of the regenerated plantlets. Colchicine concentrations of 0.05% and 0.1% produced the most tetraploids; of the 19 total tetraploids produced, 10 were produced from the treatment with a colchicine concentration of 0.1% and six were produced from treatment with a concentration of 0.05%. After flowering, these stable pink/red-fleshed tetraploid plants generated should be useful as breeding parents in our grapefruit/pummelo improvement program, especially if any show canker tolerance or reduced furanocoumarins. Use of monoembryonic tetraploids in interploid citrus crosses eliminates the need for embryo rescue to recover seedless triploid progeny; this research expands our pool of available high-quality monoembryonic tetraploid parents.

Doubled haploid plants following colchicine treatment of microspore-derived embryos of oilseed rape (Brassica napus L.)

An efficient method for producing doubled haploid plants of oilseed rape (Brassicanapus L.) was established using in vitro colchicine treatment of haploid embryos. Haploid embryos in the cotyledonary stage were treated with one of four colchicine concentrations (125, 250, 500 and 1,000 mg/L); for one of three treatment durations (12, 24 and 36 h) at one of the two temperatures (8 and 25°C) and were compared to control embryos (without colchicine treatment). The number of chromosomes, seed recovery, size and density of leaf stomata, and pollen grain size from regenerated plants were determined. No doubled haploid plants were regenerated from control embryos; however, the doubled haploid plants were regenerated from colchicine-treated embryos. A high doubling efficiency, 64.29 and 66.66% of regenerated plants, was obtained from 250 mg/L colchicine treatment for 24 h and 500 mg/L colchicine treatment for 36 h, respectively, at 8°C. Following 500 mg/L colchicine treatment for 36 h, a few plants regenerated (9 plants). At the higher colchicine concentration (1,000 mg/L), no plant regenerated. These results indicate that the colchicine treatment of embryos derived from microspores can induce efficient chromosome doubling for the production of doubled haploid lines of oilseed rape.

Induction of tetraploid ruzigrass (Brachiaria ruziziensis) plants by colchicine treatment of in vitro multiple‐shoot clumps and seedlings

AbstractTetraploid plants of ruzigrass (Brachiaria ruziziensis) have been obtained by colchicine treatment of in vitro multiple‐shoot clumps and germinated seedlings. Multiple‐shoot clumps were induced and maintained on MS basal medium with 0.5 mg L−1 2,4‐dichlorophenoxyacetic acid (2,4‐D) and 2.0 mg L−1 6‐benzylaminopurine (BAP) according to a previous report. The colchicine treatment consisted of culturing multiple‐shoot clumps on MS basal medium containing 0.0125–0.1% colchicine for 12 and 48 h. Surviving multiple‐shoot clumps were regenerated on MS basal medium containing 2.0 mg L−1 BAP. The ploidy level of plants after colchicine treatment was determined by flow cytometry. Eight tetraploid plants were obtained from multiple‐shoot clumps treated with 0.1% colchicine for 12 h. This treatment was identified as the optimum treatment and resulted in the highest frequency (28.6%) of tetraploid plants among the treatments tested on multiple‐shoot clumps. Five tetraploid plants (31.3%) were obtained when seedlings were treated with 0.1% colchicine for 3 h. Although higher concentrations of colchicine and longer durations of colchicine treatment reduced the survival rate of the explants, such treatments increased the frequency of tetraploid plants. A total of 23 tetraploid plants were obtained from 900 different colchicine‐treated multiple‐shoot clumps, and a total of five tetraploid plants were obtained from 300 colchicine‐treated seedlings. Cytological analysis affirmed the results of flow cytometry. Significant differences in leaf blade stomata were observed between diploid and tetraploid ruzigrass.

Micronuclei induced in erythrocytes of Cyprinus carpio (teleostei, pisces) by X-rays and colchicine

In the present work the induction of micronuclei in erythrocytes of Cyprinus carpio treated with X-rays and colchicine is studied for the evaluation of mutagenic effects of both clastogenic and mitoclastic (spindle poisoning) agents in this system. Three different experiments were performed treating groups of laboratory-reproduced animals with (1) single doses of X-rays (0.1, 0.5 and 2 Gy); (2) a single i.p. injection of colchicine at the concentrations: 1.6×10 −2, 8×10 −2, 0.4 and 2 mg/kg b.w. so as to mimic an acute exposure to the agent and (3) six repeated i.p. injections of the first three concentrations of colchicine, over a period of 18 days, so as to mimic a chronic exposure. Repeated blood samplings were performed by cardiac puncture over a period of about 2 months after the treatment and micronucleus frequencies were determined at multiple times on the same individuals after mutagen exposure. A dose-dependent increase in the micronucleus frequency was observed in irradiated fish and a peak value detected at 21 days. Slight increases of micronucleus frequencies were also observed in both colchicine experiments only for the highest concentrations at the earliest sampling time. Higher concentrations of colchicine clearly showed a lethal effect. According to the present data the micronucleus frequency induced by the highest colchicine dose is comparable to that observed after 0.1 Gy of X-ray irradiation.

Colchicine, an efficient genome-doubling agent for maize ( Zea mays L.) microspores cultured in anthero

The construction of maize genotypes with high haploid induction capacity made it possible to study the effect of colchicine on maize androgenesis in vitro. Anther cultures of three hybrids were treated with 0.02% and 0.03% colchicine for 3 days at the beginning of microspore induction. Colchicine added to the induction medium had no negative influence on the androgenic responses (anther induction, induction of structures of microspore origin and their regeneration ability) of the genotypes examined. However, significantly higher fertility was observed in plants originating from colchicine-treated microspores, especially at 0.03%. Cytological examinations showed that colchicine treatment before the first microspore division efficiently arrested mitosis and resulted in homozygous doubled-haploid microspores. Under the experimental conditions, the antimitotic drug had no later effect on the division symmetry of the microspore nucleus, and unequal divisions remained dominant. Callus formation from the induced microspores seemed to be more typical (ranging between 60–70%), but embryo frequency was increased by approximately 10%, especially at the higher colchicine concentration. These results suggest that the mechanism of colchicine action in premitotic maize microspores may differ from that previously observed in wheat.

Passive Mechanical Behavior of Human Neutrophils: Effects of Colchicine and Paclitaxel

The role of microtubules in determining the mechanical rigidity of neutrophils was assessed. Neutrophils were treated with colchicine to disrupt microtubules, or with paclitaxel to promote formation of microtubules. Paclitaxel caused an increase in the number of microtubules in the cells as assessed by immunofluorescence, but it had no effect on the presence or organization of actin filaments or on cellular mechanical properties. Colchicine at concentrations <1.0 μM caused disruption of microtubular structures, but had little effect on either F-actin or on cellular mechanical properties. Higher concentrations of colchicine disrupted microtubular structure, but also caused increased actin polymerization and increases in cell rigidity. Treatment with 10 μM colchicine increased F-actin content by 17%, the characteristic cellular viscosity by 30%, the dependence of viscosity on shear rate by 10%, and the cortical tension by 18%. At 100 μM colchicine the corresponding increases were F-actin, 25%; characteristic viscosity, 50%; dependence of viscosity on shear rate, 20%; and cortical tension, 21%. These results indicate that microtubules have little influence on the mechanical properties of neutrophils, and that increases in cellular rigidity caused by high concentrations of colchicine are due to a secondary effect that triggers actin polymerization. This study supports the conclusion that actin filaments are the primary structural determinants of neutrophil mechanical properties.

Colchicine-induced Amphidiploids of Rose Interspecific Hybrids

An objective of our rose breeding research is to transfer resistance to blackspot and other diseases from wild diploid species to modern rose cultivars. Interspecific hybrids among blackspot-resistant diploid species were chosen for chromosome doubling to produce fertile amphidiploids that could be hybridized to the tetraploid commercial germplasm. Five such F1 interspecific hybrids were treated with colchicine. The study included two different application procedures (shake in colchicine solution or colchicine in media), four colchicine concentrations (0.05%, 0.1%, 0.15%, and 0.20%), and five treatment periods (1, 3, 5, 8, and 10 days). After colchicine treatment, all the materials were cultured in vitro. One thousand-thirty-seven surviving explants were selected for typical “gigas” characteristics of doubled diploids. Chromosome counts on shoot tips of these selected genotypes confirmed 15 amphidiploids. The best colchicine treatment varied among the interspecific hybrids. Higher colchicine concentrations or duration reduced growth rating, rooting, and percent survival. The recognition of amphiploids and ploidy chimeras from young seedlings will also be discussed.

Efficient in vitro Chromosome Doubling During Beta vulgaris Ovule Culture

AbstractThe effect of in vitro colchicine treatment of sugar beet ovules, after 7 days culture, on embryo formation, regeneration and ploidy of regenerated plants was studied with 5 concentrations of colchicine and 5 durations of treatment arranged as a 5 × 5 factorial in incomplete blocks. The best results were obtained with the shortest duration of treatment (5 hours) and the highest concentration of colchicine (0.4 %) giving 5.0 diploid plants per 100 ovules with 62.1 % of regenerated plants being diploid. Statistical analysis revealed that treatment effects could be separated into a toxic effect reducing embryo formation and a chromosome doubling effect affecting percentages of diploid regenerated plants. Toxic effects on embryo formation could be explained by simple exponential decay models, toxicity of the drug (decay constant) increasing linearly with duration of treatment. Duration of treatment had no effect on chromosome doubling percentages. The effects of colchicine concentration on chromosome doubling were explained by an exponential saturation model with spontaneous chromosome doubling of 8.1 % and saturation at 51.4 % diploid plants at 0.2 % and higher colchicine concentrations. In addition, treatments increased percentages of 4N and 6N plants from 0 % without colchicine to 10 % on average for treated ovules. A response surface model fitted to the total yield of diploid plants per ovule indicated that shorter durations of treatment and higher colchicine concentration may improve results.

Compensatory alterations in receptor-stimulated phosphoinositide hydrolysis in the hippocampus vary as a function of dose of colchicine

The stimulation of inositol phospholipid (PI) hydrolysis by various receptor agonists was measured in the hippocampus of rats 12 weeks after various concentrations (0.5–2.0 μg/site) of colchicine were infused into the dentate gyrus. Colchicine produced a dose-related decrease in the average width and length of the granule cell line; the pyramidal cells in CA1 and CA3 regions of the hippocampus were affected only at higher concentrations of colchicine. Compensatory increases in receptor-mediated hydrolysis of phospho-inositides (PI) in hippocampal slices were seen at 100 μm carbachol and ibotenic acid in rats receiving 1.5–3.5 μg colchicine/site. Compensatory increases in norepinephrine (100 μm) and N- methyl- d- aspartate (100 μm) stimulated PI were seen at 2.5–3.5 and 3.5 μg colchicine/site, respectively. Compensatory increases in PI hydrolysis were not seen in slices from animals receiving 0.5 μg colchicine/ site. These data support the hypothesis that the signal transduction system in the hippocampus undergoes a compensatory change following experimentally induced destruction of dentate gyrus granule cells. In addition, these changes occur for more than one neurotransmitter and the alterations vary as a function of the size of the lesion.

Colchicine-induced Ciliated Vacuoles in Tracheal Mucosa

In most cells the microtubules are destroyed and disappear after administration of colchicine in concentrations as low as 10(-6) M; colchicine inhibits the polymerization of tubulin and destroys the microtubules. Ciliary microtubules have resistance to colchicine but can, on the other hand, be destroyed by high concentrations of colchicine. In this study, we treated rabbits with considerably high concentrations (10 or 20 mg/100 g body weight) of colchicine for four successive weeks and examined the effects on the tracheal cilia. Abdominal administration of colchicine did not affect the morphology and structure of the cilia projecting on the cellular surface. However, ciliated vacuoles were observed in tracheal epithelial cells of rabbits treated with colchicine. The occurrence of such ciliated vacuoles depended on the dosage of colchicine: 2.4 +/- 0.4 per 100 microns epithelial length when treated with 10 mg/100 g body weight of colchicine, and 3.8 +/- 0.3 per 100 microns epithelial length when treated with 20 mg/100 g body weight. Some cilia present in ciliated vacuoles were pathological. In conclusion, a considerably high dosage of colchicine can inhibit ciliary microtubules during ciliogenesis, resulting in ciliated vacuoles.