共查询到20条相似文献,搜索用时 31 毫秒
1.
Summary The ultrastructural localization of acid phosphatase activity was investigated in ultrathin (0.05 m) and semithin (0.5 m) sections of the small intestinal epithelial cells of postnatal rats. Until around the 15th day of neonatal life acid phosphatase activity in the duodenal and jejunal epithelial cells was observed on the microvillous membrane, the membrane of the tubulo-vacuolar system, the lateral cell membrane, the lysosomes, the Golgi apparatus and the GERL of Novikoff (1963). After about the 15th neonatal day, the tubulo-vacuolar system enzyme disappeared from both cells. Acid phosphatase activity then became localized on the microvillous membrane, the lateral cell membrane, the lysosomes, the Golgi apparatus, and the GERL, as in adult rats. During the suckling period, acid phosphatase in the ileal cells could be seen on the microvillous membrane, the lateral cell membrane, the Golgi apparatus, the GERL, the membrane of tubulo-vacuolar system and the supranuclear vacuole. At weaning, however, the tubulovacuolar system and the supranuclear vacuole enzyme disappeared, and only the lysosomes and the GERL of these cells showed acid phosphatase activity, as in the adult rat. It was concluded that the acid-phosphatase-containing tubulo-vacuolar system and the supranuclear vacuole in the epithelial cells of the distal intestine of suckling rats may possess a strong phagolysosomal function as well as having an absorptive capacity. 相似文献
2.
Synopsis The fine structure and cytochemistry of the intestinal epithelial cell of the fowl have been investigated. The fine structure of the mature absorptive cell of the fowl duodenum was very similar to that described for man and other mammals. Minor differences were the thinner microvillous glycocalyx, the unusual length of the cells and their microvilli, and the wide distribution of lysosomal bodies. The membrane-associated enzymes alkaline phosphatase, ATPase (pH 7.2) and leucine naphthylamidase were mainly associated with the brush border; this organelle also gave positive reactions for mucopolysaccharides and phospholipids. No enzyme activities were found in the terminal web.The distribution of lysosomes between the terminal web and the Golgi apparatus was correlated with the granular localization of the lysosomal enzymes acid phosphatase, -glucuronidase and non-specific esterase. The mitochondrial enzyme succinate dehydrogenase was seen to be localized in rod-like dots which marked the distribution of mitochondria in the absorptive cell. The localization of mitochondrial ATPase (pH 9.4) was not clearly demonstrated because of diffusion artifacts. The region of the Golgi apparatus gave a strong reaction for thiamine pyrophosphatase, together with weak reactions for acid and alkaline phosphatases after extensive overincubation.The endoplasmic reticulum-associated enzymes glucose-6-phosphatase and nonspecific esterase were distributed throughout the absorptive cell, with a maximum activity apical to the Golgi apparatus. Additionally, the jejunal absorptive cells showed endoplasmic reticulum-as well as lysosomal-associated -glucuronidase. 相似文献
3.
C. Stacy French 《Archives of microbiology》1967,59(1-3):93-103
Summary Absorption spectra of a young and an old culture of the diatom Pheodactylum tricornutum were measured in thin layers between two opal glass sheets. The spectra at 24° and at -196°C were replotted to give equal areas from 730–625 m to allow direct comparison. At 24°C the spectrum for the difference between the two cultures had a negative component of 18 m half width centered at 675 m and a positive region of W0.5=26 m near 700 m.The spectra at -196°C may be somewhat distorted by clumping of the cells during freezing but nevertheless the 16 day culture clearly showed a smaller proportion of Ca 670 to Ca 680. This older culture has a shoulder due to a 707 m component. The difference curve at -196°C shows the decrease of an unsymmetrical band peaking at 669 m and an increase at 695 m in addition to the 707 m component. Due to the possibility of distortion, the presence of an actual component at 695 is doubtful in these particular cultures.The room temperature spectrum in the chloropyhll a region for the 5 day culture can be closely fitted by a single probability curve at 675 m having a half-width of 31 m. The sum of two components, with widths more reasonable for chlorophylls, also matched the data well enough. These two probability curves, of 22 m half width, centered on 669 and 683.2 m and had a height ratio, h669/h683 of 1.18. In the 16 day culture the ratio for these bands changed to 1.11 and there was extra absorption around 700 m.Dedicated to Professor C. B. van Niel on the occasion of his 70th birthday 相似文献
4.
Margherita A. Barracco Bernard Duvic Kenneth Söderhäll 《Cell and tissue research》1991,266(3):491-497
Summary A -1,3-glucan-binding protein (GBP) was purified from crayfish plasma, and incubated with laminarin (L), a -1,3-glucan. The GBP reacted with laminarin (GBP-L) induced strong spreading and partial degranulation of isolated and separated crayfish granular haemocytes. However, neither the GBP nor laminarin alone induced any changes in the crayfish granular cells. When monolayers of granular haemocytes were incubated with 20 g of GBP-L, more than 82% of the haemocytes were affected. The activity of GBP-L on granular cells was dose-dependent and a plateau was reached at 10 g of GBP-L. The degranulation of crayfish haemocytes induced by GBP-L seemed to occur by a regulated exocytosis, since it was strongly inhibited by specific blockers of this process such as SITS or calmidazolium. Monospecific anti-GBP antibodies also totally blocked the effect of GBP-L on crayfish granular cells. Indirect immunofluoresence staining demonstrated that the GBP-L could bind to the surface of granular cells, whereas GBP did not bind or bound very weakly to the haemocyte surface. 相似文献
5.
Summary
Vicia faba callus line (VFS 1), isolated from expiants of immature embryo, grew satisfactorily onMurashige andSkoog complete medium with 1.38 M 2,4-D, or with 0.92 M 2,4-D to which 1.0 M kinetin was added. It also grew well on the B 5 modified medium containing 2.3 M 2,4-D and 25.0 M kinetin. On the last of these media the cultures grew more uniformly and without necrosis. They also showed diminishing variation in polyploidy in favour of diploids and corresponding aneuploids (hypodiploids).After being cultured for nearly three years on MS containing 1.38 M 2,4-D, 8–33% of cultures of VFS 1 were able to regenerate roots when transferred to either MS half strength with 5.37 M NAA, or to a medium without 2,4-D, or else to media with the addition of kinetin only (in various concentrations). 相似文献
6.
J. Mitsuhashi T. D. C. Grace D. F. Waterhouse 《Entomologia Experimentalis et Applicata》1970,13(3):327-341
Serial dilutions of 20 insecticides were examined for their effects on the growth of insect cells cultivated in vitro. No differences in susceptibility were found for cells derived from the moth Antheraea eucalypti and the mosquito Aedes aegypti.Rotenone was the most effective inhibitor investigated, decreasing the rate of cell division at 0.001 g/ml. Malathion and diazinon first showed effects at 12 g and 112/ml respectively. Toxicants first effective at 10 g/ml included pp-DDT, dieldrin, pyrethrins and sodium arsenate; at 100 g/ml they included lindane and carbaryl; at 1000 g/ml only nicotine sulphate.The majority of insecticides tested (principal exception rotenone) were very much more toxic to last instar A. aegypti larvae than to the insect cells, suggesting that the functions of highly organized tissues are more readily interfered with than those of individual cell types comprising them.
Zusammenfassung Verdünnungsserien von 20 Insektiziden wurden auf ihren Effekt auf das Wachstum von in vitro kultivierten Insektenzellen untersucht. Die untersuchten Zellen stammten aus Kulturen von Ovariolen von Antheraea eucalypti-Puppen und von Gewebe von Aedes aegypti-Larven. Rotenon erwies sich als das wirksamste Insektizid: es verlangsamte die Zellteilung in einer Konzentration von 0.001 g/ml. Malathion wurde erst in einer Konzentration von 12 g/ml wirksam, Diazinon bei 112 g/ml. Mehrere Insektizide zeigten erste Wirksamkeit bei 10 g/ml; diese waren: pp-DDT, pp-DDD, pp-DDE, Methoxychlor, Aldrin, Dieldrin, Pyrethrine, Allethrin und Natriumarsenat. Insektizide mit einer ersten Wirksamkeit bei 100 g/ml waren Lindan, Isolan, Dimetilan, Carbaryl, DNOC und Piperonylbutoxid. Nikotinsulfat war erst bei 1 mg/ml oder bei höheren Konzentrationen wirksam. Zwischen den Antheraea- und Aedes-Zellen wurde kein Unterschied in der Empfindlichkeit gegen die verschiedenen Insektizide gefunden. Bei niedrigen Konzentrationen zeigten Malathion und Natriumarsenat erst nach dem 4. Tag bedeutendere Effekte. Ein schwacher synergistischer Effekt wurde beim Mischen von Pyrethrinen mit Piperonylbutoxid in niedrigen Konzentrationen beobachtet, nicht aber bei hohen Konzentrationen.Bei der Mehrzahl (17 von 19) der Insektizide waren die Zellen in 10 bis 10.000 mal höheren Insektizid-Konzentrationen zu überleben fähig als A. aegypti-Larven im letzten Stadium. Rotenon war das einzige Insektizid, dessen Toxizität auf Zellen stärker war (10.000 Mal) als auf intakte Larven.相似文献
7.
M. Hossain B. K. Biswas M. R. Karim S. Rahman R. Islam O. I. Joarder 《Plant Cell, Tissue and Organ Culture》1994,39(3):265-268
Elephant apple (Feronia limonia L.). was micropropagated on MS medium containing 4.4 M benzyladenine and 4.6 M kinetin using cotyledon explants taken from in vitro-grown seedlings. Adventitious buds formed on the cotyledon developed into shoots that were rooted in half-strength MS medium containing 0.57 M indoleacetic acid and 0.49 M indolebutyric acid. Plants were successfully established in soil.Abbreviations BA
6-benzyladenine
- IAA
3-indoleacetic acid
- IBA
3-indolebutyric acid
- MS
Murashige & Skoog 相似文献
8.
Peter Frisk Anders Saetre Beatriz Couce Bo Stenerlöw Jörgen Carlsson Ulf Lindh 《Biometals》1997,10(4):263-270
Effects of Pb2+, Ni2+, Hg2+ and Se4+ on cultured human glioma U-343MG cells were investigated considering uptake, toxicity and, in combination with radiation, clonogenic cell survival. The cells were exposed to 0-100 m of the metals for a week before the evaluation. The tests showed a tendency to toxicity with 10 m nickel although not significant (P > 0.05). Selenium, lead and mercury exerted a significant toxicity (P < 0.05) at 2.5 m, 10 m and 1 m, respectively. To challenge the clonogenic cell survival capacity, the cells were irradiated with60Co photons after being exposed to the highest nontoxic concentration of the different metals. The clonogenic cell survival tests, after irradiation, showed no significant change if the cells were exposed to 5 m nickel, 0.5 m selenium or 5 m lead compared with those not exposed. Mercury, 0.1 m, gave a relative reduction in survival compared with only irradiated cells of 58 ± 17%. Thus, only mercury affected the radiation-induced damage and/or repair. When exposed to the highest nontoxic concentrations of the different metals, the cultures did not display a significant uptake ratio (metal concentration ratio of exposed cells to control cells) of nickel (3.1 ± 3.3), only a small uptake ratio of selenium (4.0 ± 0.4), while there was a large uptake ratio of both lead (2.6 ± 1.7) x 102 and mercury (1.5 ± 0.2) x 101. The results indicated that nickel was neither especially toxic nor influenced the clonogenic cell survival after irradiation. Mercury was more toxic and also influenced the radiation sensitivity. Lead was taken up strongly but did not influence the radiation sensitivity. Selenium accumulated but gave no detectable effect on the radiation sensitivity. 相似文献
9.
K. J. Clarke B. J. Finlay E. Vicente H. Lloréns M. R. Miracle 《Archives of microbiology》1993,159(6):498-505
In natural populations of the anaerobic phototrophic bacterium Chromatium weissei, many cells support a prokaryotic epibiont. This epibiont appears in several forms, all from the life cycle of a single species. A typical epibiont consists of one to five flattened coccoid cells stacked one above the other, perpendicular to the C. weissei surface. The cells at the proximal and distal ends of the stack are 0.6 m in diameter and 0.8 m in length; mid-stack cells are slightly shorter. A typical three or four cell stack is 2 m in length. Small mesosome-like inclusions in the distal cell are involved in the development of droplet shaped cells which are released from the end of each stack. These specialised droplet cells probably transfer to new hosts when C. weissei cells collide, thereafter developing into new epibiont stacks. It is likely that the epibiont grows heterotrophically using the substantial production of dissolved organic carbon within the dense plates of photosynthesising C. weissei which develop naturally. Thus the epibiont uses its unusual method of growth and dispersion to maintain position in the microbial plate upon which it depends. 相似文献
10.
Summary Ultrastructural analysis of the mature viable unhydrated pollen of maize,Zea mays from dehiscent anthers shows that the sperm cells are physically distant, each bounded by an envelope comprising their own plasma membrane and the inner plasma membrane of the vegetative cell. The chondriome is unusual in containing one or more filamentous complexes, up to 12m in length appressed to the side of the sperm nucleus. The extensions at each end of the elongate sperm cells contain longitudinally-oriented arrays of endoplasmic lamellae. In a three-dimensional reconstruction of serial thin sections, there is a long J-shaped sperm, c. 35 × 5m and up to 1m in thickness, sited within pointed evaginations of the vegetative nucleus and a second shorter sperm c. 20 × 5m and up to 3.5m in thickness.Abbreviations PA-TCH-SP
periodic acid-thiocarbohydrazide-silver proteinate
- DAPI
4,6-diamino-2-phenylindole
- SC
sperm cell
- Sn
sperm nucleus
- Ua-Pb
Uranyl acetate-lead citrate staining
- ER
endoplasmic reticulum 相似文献
11.
Summary Fluorochromed heavy meromyosin (TRITC-HMM) was microinjected as a molecular probe into small sandwich-plasmodia of Physarum polycephalum with the aim to demonstrate the spatial morphology and to analyze the dynamic activity of the fibrillar actin system in the living state. The plasmodia display different fibrillar organizations with a polygonal arrangement in the front region (FR) and a parallel or helical arrangement along protoplasmic veins in the intermediate (IR) and uroid region (UR). Quantitative evaluations by measuring the total length, lifetime, dynamic activity, long-term stability and optical density of fibrils reveal distinct differences between the three plasmodial regions: The total length (FR = 27.1 ± 18.5 m, IR = 24.8 ± 12.9 m, UR= 12.3 ± 4.7 m), the lifetime (FR = 12.2 ± 3.4 min, IR=10.5 ± 3.7 min, UR = 6.0 ± 3.4 min), and the dynamic activity as measured in length changes per min (FR = 17.9 ± 11.3 m, IR = 13.1 ± 3.9 m, UR = 8.3 ± 3.9 m) distinctly decrease from the front to the uroid region. On the other hand, the greatest stability as determined by lifetime changes in length (FR = -2.4 ± 16.2 m, IR = 0.3 ± 10.1 m, UR = -6.6 ± 8.9 m) and the highest optical density as expressed in grey-values (FR = 57.0 ± 14.1 gv, IR = 115.6 ± 26.1 gv, UR 62.5 ± 8.1 gv) were found for actomyosin fibrils of the intermediate region. The morphological and physiological data of the present paper are discussed with respect to the biological significance of the fibrillar microfilament system in Physarum polycephalum. 相似文献
12.
Synaptoneurosomes isolated from cerebral cortices of male Sprague-Dawley rats were used for studying GABAA receptor-regulated chloride influx. The in vitro effects of GABA antagonists, SR 95531 (a pyridazinyl GABA derivative) and bicuculline, on pentobarbital-stimulated, muscimol-stimulated or flunitrazepam-enhanced, muscimol-stimulated chloride uptake were studied. The chloride uptake was determined at 30°C, for 5 sec. Pentobarbital and muscimol produced a maximal stimulation of chloride uptake in cortical synaptoneurosomes at 500 M and 50M, respectively. SR 95531 as well as bicuculline had no effect on the basal uptake of chloride. Whereas, SR 95531 (0.3–30 M) and bicuculline (0.1–100 M), when added 5 min before muscimol (50 M), produced a significant concentration-dependent inhibition of muscimol (50 M)-stimulated chloride uptake (IC50
s of 0.89±0.11 M and 13.45±2.10M, respectively). In studies of the inhibitory effects of SR 95531 and bicuculline on pentobarbital (500 M)-stimulated chloride uptake, the IC50
s were 0.81±0.12 M and 3.86±1.14 M, respectively. SR 95531 exhibited a more potent inhibitory effect than bicuculline on flunitrazepam-enhanced, muscimol-stimulated chloride uptake. The results revealed that SR 95531 has a more potent antagonistic effect than bicuculline on GABAA-regulated chloride flux. 相似文献
13.
Iavicoli Ivo Sgambato Alessandro Carelli Giovanni Ardito Raffaele Cittadini Achille Castellino Nicolò 《Molecular and cellular biochemistry》2001,222(1-2):35-40
Lead (Pb) is an environmental toxicant that can induce structural and functional abnormalities of multiple organ systems, including the central nervous and the immune systems. The aim of this study was to evaluate the effects of extracellular Pb supplementation on the cellular content of the metal and on the proliferation and the survival of normal rat fibroblasts.We found that the concentration of Pb in the culture medium was 0.060 M and the normal Pb concentration in rat fibroblasts was 3.1 ± 0.1 ng/107 cells. Then we exposed the cells to increasing concentration of Pb (as Pb acetate) from 0.078–320 M. We observed a dosedependent inhibition of cell proliferation after 48 h, which was already apparent at a concentration of 0.312 M (p = 0.122) and became statistically significant for concentration higher than 0.625 M (p = 0.0003 at 5 M). Cell proliferation was completely compromised at 320 M Pb total inhibition of cell proliferation.To investigate the mechanisms of Pbmediated inhibition of cell proliferation, we evaluated the occurrence of apoptosis in the same cells and found that cytosolic DNA fragments, hallmark of apoptotic cell death, increased significantly at Pb concentrations from 2.5–10.0 M. The occurrence of apoptosis was also confirmed by FACS analysis which showed the appearance of a subdiploid peak at Pb concentrations from 5–20 M. The distribution of cells in the cell cycle showed a dosedependent accumulation of cells in the G0/G1 phase mainly compensated by a decrease in the percentage of cells in the S phase. In conclusion, our results demonstrate that induction of apoptosis contributes to the Pbinduced inhibition of cell proliferation in rat fibroblasts. 相似文献
14.
Prof. Rudolph L. Pipa 《Cell and tissue research》1978,193(3):443-455
Summary Retrograde diffusion and precipitation of Co2+ reveals in the ipsilateral pars lateralis (PL) and contralateral pars intercerebralis (PI) of the brain neurons that enter the corpus cardiacum (CC), and, possibly, the corpus allatum (CA) on each side. The PL group consists of 29.6±8.4 somata that fill. Of these, 5.6±0.6 exceed 25 m in diameter, 14.3±2.7 range from 15–25 m, and 9.6±7.6 are smaller than 15 m. After CoCl2 was applied to the right CC-CA of two males, 239 and 265 somata in the left PI stained. Except for 16 ranging from 30–45 m and chiefly located anteriorly, a majority of these somata measured 10–25 m.The only somata revealed by staining whole brains with the performic acid-resorcin fuchsin method are neurosecretory cells 10–20 m in diameter located within the PI. In starved adult males there are 92.4±8.1 on the right, and 93.2±6.9 on the left. The largest somata in the PL group contain numerous granules that stain with paraldehyde fuchsin. These somata also fill with Co2+, and belong to neurosecretory cells that extend into the CC-CA.The cerebral distribution of branches from the PL group, and the relationship of these to the corpora pedunculata, central body, and arborizations from the PI decussation are described. 相似文献
15.
Dr. M. E. Stoeckel S. Schimchowitsch J. C. Garaud G. Schmitt H. Vaudry M. J. Klein A. Porte 《Cell and tissue research》1985,242(2):365-370
Summary The immunogold technique, employing antisera with clear-cut specificities, was used to localise different processing stages of pro-opiomelanocortin (POMC) in rabbit melanotropic cells. While the antiserum against
3-MSH labelled all the secretory granules including intrasaccular condensations in the Golgi apparatus, antisera against -MSH only labelled extra-Golgi secretory vesicles (SV). All extra-Golgi SV were likewise labelled with the three antisera against -MSH used, despite their different specificities for the desacetylated, N-acetylated or C-amidated forms of the peptide. The antibody against -endorphin also labelled the extra-Golgi SV, while only some SV were labelled with the antibody against -endorphin. These results correlate with biochemical data in favour of mainly — if not exclusively — intragranular processing of POMC. Except for 3-MSH, the cleavage of which could coincide with Golgi packaging of secretory material, other post-translational modifications of the precursor seem to occur when SV are discharged outside the Golgi area. The cleavage of -endorphin appears to be a later step in POMC processing, occurring in some mature SV. 相似文献
16.
Impact of lead exposure on pituitary-thyroid axis in humans 总被引:2,自引:0,他引:2
Baljinder Singh Vinod Chandran Harish K. Bandhu Bhagwant R. Mittal Anish Bhattacharya Surinder K. Jindal Subhash Varma 《Biometals》2000,13(2):187-192
Thyroid function tests (serum levels of thyroxine-T4, triiodothyronine-T3 and thyroid stimulating hormone-TSH) were performed in fifty-eight men (mean age: 31.7±10.6 years; mean duration of lead exposure: 156.9±122.7 months). These subjects were exposed to lead either as petrol pump workers or automobile mechanics. The mean whole blood lead (Pb-B) levels were 2.49±0.45 mole/l (51.90±9.40 g/dl) in the lead exposed workers and were approximately 5 times higher than in the control (n=35) subjects. No significant alteration was seen in their mean T3 and T4 levels as compared with the controls. Interestingly, T3 was significantly lower with the longer (210 months) exposure time in comparison with the group having shorter (29 months) exposure duration. The mean TSH levels were significantly (p<0.01) higher in workers exposed in comparison with the control group. This rise in TSH was independent of exposure time, but it was definitely associated with the Pb-B levels. The increase being more pronounced with mean Pb-B levels of 2.66±0.2 mole/l (55.4±4.25 g/dl) when compared with the group having mean levels of 1.51±0.30 mole/l (31.5±6.20 g/dl). The rise is TSH associated with Pb-B levels was only statistical valid, however, the levels fall within the normal laboratory range. We thus conclude that the Pb-B levels of 2.4 mole/l (50 g/dl) could enhance the pituitary release of TSH without having any significant alterations in the circulating levels of T3 and T4. 相似文献
17.
Summary The incidence of myosatellite cells associated with white and red muscle fibres of the parietal muscle and red fibres of the craniovelar muscle was estimated by quantitative electron microscopy in the Atlantic hagfish (Myxine glutinosa, L.). Myosatellite cell nuclei constitute 3, 11 and 23 % of the total number of nuclei inside the basal lamina of the three types of muscle fibres, respectively. However, the total number of nuclei is highest in white fibres, most of the nuclei belonging to striated muscle cells. Myosatellite cell profiles in transverse sections constitute 23, 41 and 61 % of the number of muscle fibre profiles of the three types, respectively. The intervals between adjacent myosatellite cells are 135 m in white fibres, 55 m in red parietal fibres, and only 25 m in craniovelar fibres. Since craniovelar fibres are also comparatively thin, myosatellite cells constitute a significant fraction of the volume inside the basal lamina in these fibres. The myosatellite cells are 30–50 m long and up to 5 m thick. Some myosatellite cells possess few organelles, whereas others appear to contain many free ribosomes, granular endoplasmic reticulum, prominent Golgi apparatus and lysosome-like bodies.This investigation was supported by the Norwegian Research Council for Science and the Humanities (NAVF grant No. C20.30–37). The authors are indebted to Jorunn Line Vaaland and Berit Branil for technical assistance, and to Dr. Finn Walvig, Biological Station, University of Oslo, Drøbak, for supplying the hagfish 相似文献
18.
Chernobelskaya O. A. Grigoriev I. S. Alieva I. B. Vorobjev I. A. 《Russian Journal of Developmental Biology》2001,32(1):51-58
It is generally assumed that microtubules in tissue culture cells extend from the centrosome to cell periphery, and the length of individual microtubules averages several dozens of microns. However, direct electron-microscopic measurements have cast some doubt on this assumption. In this study, the average length of microtubules in cultured Vero cells was estimated using a combined approach. The length of free cytoplasmic and centrosomal microtubules was determined by means of electron microscopy in serial sections; concurrently, the length of free microtubules in the lamella was measured in preparations stained with tubulin antibodies (an indirect immunofluorescent method), by tracing saltatory particle movements along the microtubules in living cells. According to the data of immunofluorescent microscopy, microtubule length in the lamella averaged 4.57 ± 3.69 m. However, since two or more microtubules can overlap, their length may be slightly overestimated by this method. On the other hand, saltatory movements are easy to monitor and measure fairly accurately, but their range may be shorter than the actual microtubule length because of a limited processiveness of motors (kinesin and dynein). On average, the trajectories of saltatory movements in living cells were 3.85 ± 0.72 m long. At the electron-microscopic level, microtubule length was analyzed using pseudo-three-dimensional reconstructions of the microtubule systems around the centrosome and in the lamella. The length of free microtubules in the lamella reached 18 m, averaging 3.33 ± 2.43 m; the average length of centrosomal microtubules was 1.49 ± 0.82 m. Good correspondence between the data on microtubule length and arrangement obtained by different methods allows the conclusion that most of the free microtubules in Vero cells actually have a length of 2–5 m; i.e., they are much shorter than the cell radius (about 25 m). Microtubules extending from the centrosome are shorter still and do not reach the cell periphery. Thus, most microtubules in the lamella of Vero cells are free and their ordered arrangement is not associated with their attachment to the centrosome. 相似文献
19.
Archana Mathur Ajay Kumar Mathur Arun Kumar Kukreja Paramvir Singh Ahuja Bali Ram Tyagi 《Plant Cell, Tissue and Organ Culture》1987,10(2):129-134
A tissue culture procedure was developed for the establishment and propagation of a colchi-autotetraploid of Rauvolfia serpentina for possible commercial exploitation. Multiplication of autotetraploid shoots was obtained either through axillary bud elongation on Murashige and Skoog [1] medium (MS) containing 2.65 M (0.5 mgl–1) -naphthaleneacetic acid and 0.33 M (0.05 mgl–1) kinetin, or via multiple shoot formation on MS medium supplemented with 4.44 M (1.0 mgl–1) 6-benzylaminopurine and 0.53 M (0.1 mgl–1) -naphthaleneacetic acid. Rooting could be induced by transferring the shoots to MS medium containing 7.95 M (1.5 mgl–1) -naphthaleneacetic acid alone. The plantlets, thus formed, were tetraploid in nature by cytological observations of the root tips. They exhibited 80–90% success in establishment under glass house and field conditions. 相似文献
20.
Cryphodera kalesari n. sp., recorded on Colebrookea oppositifolia Sm. from the Kalesar forests (Haryana), India, is described. Females: swollen, saccate, with two to three lip annules, with vulval lips protruding. Second stage juveniles: length 384±19 m, spear=26.5±1 m, tail 46.5±6 m, hyaline portion 21.5±2.5 m, en face dorsal and ventral arcs of head skeleton bifurcate. Males: not found. 相似文献