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1.
Sweet potato (Ipomoea batatas L.) embryos excised from the fertilized ovules of 6- to 12-day-old capsules were cultured on MS medium supplemented with NAA, BA, GA separately and in combinations. GA was found essential for initial morphogenesis of globular and heart stages. Seedlings were recovered from late globular stage onwards but recovery was best from advanced embryo stages. Differentiated embryos produced multiple shoots on MS medium +1M NAA÷2M BA +0.5M GA. 相似文献
2.
R.F. Gagliardi G.P. Pacheco S.P. Coculilo J.F.M. Valls E. Mansur 《Biodiversity and Conservation》2000,9(7):943-951
In vitro regeneration of wild groundnut species from Section Extranervosae (Arachis villosulicarpa, A. macedoi, A. retusa, A. burchellii, A. pietrarellii, A. prostrata, A. aff. prostrata and a new species) was examined for the purpose of germplasm renewal and conservation. Seeds of different ages, stored at the seed bank of CENARGEN/EMBRAPA were either inoculated on culture medium or used as a source of embryo axis and cotyledon explants. Whole seeds failed to germinate on MS either without growth regulators (MS0) or supplemented with 10 M TDZ. Embryo axes cultured on MS0 produced only single plants. In the presence of 8.8 M BAP these explants showed multi-shoot formation. Cotyledons cultured on MS supplemented with 110 M BAP developed adventitious shoots through direct organogenesis. Plant regeneration was obtained from A. villosulicarpa, A. macedoi, A. retusa, A. burchellii and A. pietrarellii both from embryo axes and cotyledons. Explants from A. prostrata and A. aff. prostrata did not produce regenerants. Rooting of shoots was induced in the presence of 5.4 M NAA. Primary plants derived from these explants were further multiplied by culturing nodal segments on MS medium plus 2.7 M NAA. 相似文献
3.
R. Salceda 《Neurochemical research》1980,5(5):561-572
A specific system for taurine transport is present at the early stages of development in both chick and rat retinas. The results obtained with taurine analogs indicate a high degree of specificity of taurine uptake. Two transport systems were detected for the adult rat retina: a high-affinity (K
m
21 M) and a low-affinity transport system (K
m
312 M). On the other hand, in the adult chick retina, only a low-affinity transport system (K
m
580 M) could be detected. Nevertheless, embryo chick retina accumulated [3H]taurine by two different kinetic mechanisms withK
m
s of 242 M and 21 M for the low- and high-affinity processes, respectively. Taurine uptake systems were absolutely Na+ dependent. The sodium-dependence curve for taurine uptake was sigmoid. These mechanisms appear not to be mediated by a Na+ cotransport system. In spite of the differences observed in taurine uptake in both species, in each of them it closely parallels the changes brought about by the morphological and functional maturation of the retina. 相似文献
4.
Summary The spermatozoon of Oikopleura dioica is about 30 m long, with a spherical head, about 1 m wide, a 3 m long and 1 m wide midpiece, and a 25 m long tail with a tapered end piece. The head contains a nucleus with the chromatin volume limited to about 0.1 m3. A small acrosome is found in an anterior inpocketing, and a flagellar basal body in a posterior inpocketing of the nucleus. The midpiece contains a single mitochondrion with the flagellar axoneme embedded in a groove along its medial surface. The flagellar axoneme has the typical 9 + 2 substructure, and the basal body the typical 9+0 substructure. A second centriole and special anchoring fibres are absent. 相似文献
5.
H. M. Häggman T. S. Aronen A. -M. Stomp 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》1996,93(5-6):840-848
Scots pine plantlets were produced via tissue culture using cotyledons excised from germinated embryos as explants. The optimum tissue culture conditions were: 1/2GDbasal medium gelled with agar-Gelrite during shoot formation and with agar during rooting, inclusion of 5.0M benzylaminopurine (BAP) and 0.05 M naphthaleneacetic acid (NAA) for 2 weeks for shoot induction, and repeated 2.7 M NAA pulses of 1 week for rooting. Micropropagation success was genotype-dependent. Average multiplication rates varied among experiments from 3 to 15 shoots per embryo. The maximum shoot production from a single embryo was 35. Rooting was the most difficult phase in the propagation process. Most of the plantlets had a plagiotrophic and highly branched growth habit when growing in the greenhouse. Some individuals produced megasporangiate strobili at the age of 3 years and microsporangiate strobili with viable pollen at the age of 4 years. Early-flowering clones and the ability to conserve seedlings from which cotyledons have been cultured give new possibilities for accelerated tree breeding. 相似文献
6.
The ultrastructural changes produced by iodine-potassium iodide solution on yeast cells of Sporothrix schenckii were investigated by transmission electron microscopy in order to clarify the mechanism of oral potassium iodide therapy for sporotrichosis. Yeast cells were dipped with solutions containing various concentrations of iodine. The rate of germination decreased markedly between the range of iodine concentrations from 0.63 g/ml to 5.0 g/ml. No significant ultrastructural changes were seen at the concentration of the iodine of 1.25 g/ml (80% germination) or less. In the concentration of 2.5 g/ml (50% germination), normal cells and degenerated cells coexisted. When the cells were treated with 5.0 g of iodine per ml (0% germination) or more, their interior structures were completely destroyed. It is assumed that iodine treatment of the organism causes rapid destruction in the whole cell. 相似文献
7.
Callus regeneration was observed from flower buds of Allium senescens var. minor inoculated in BDS, MS or B5 medium supplemented with 4.4 M benzyladenine alone or in combination with 4.5 M 2,4-dichlorophenoxy-acetic acid (2,4-d), with 2,4-d and kinetin (4.5 M/4.6 M) or with 5.3 M naphthaleneacetic acid. Ovules enlarged initially but the embryogenic tissue degenerated as callus development progressed from the nectar regions of the petals. Shoot buds and leaf primordia developed from the meristematic protuberances that originated from the surface of the callus. BDS medium with 4.5 M 2,4-d and 13.3 M BA was most suitable for shoot multiplication. The regenerated shoots were rooted in respective liquid medium without any growth regulators and successfully transferred to soil with 90% survival rate.Abbreviations BA
N6-benzyladenine
- 2,4-d
2,4-dichlorophenoxyacetic acid
- NAA
-naphthaleneacetic acid 相似文献
8.
Sabine P. Kuhn Robert M. Pfister 《Journal of industrial microbiology & biotechnology》1990,6(2):123-128
Summary
Zoogloea ramigera 115 was immobilized into beads of calcium-alginate and placed into batch air-bubbled column reactors. In the absence of any added nutrients the immobilized bacterium adsorbed Cd from solutions containing levels of 2 and 20 g ml–1 per day, over a period of 21 and 20 days, respectively. Adsorption of Cd from solutions containing 20 g ml–1 Cd was better than 90% for 16 days. Beads treated with Cd at 2 g ml–1 never adsorbed less than 95% of the metal. Alginate adsorbed Cd as well, but inclusion of cells changed the effectiveness of adsorption. Of a 250 g ml–1 Cd solution, alginate adsorbed 70.4% Cd in 60 min whereas alginate plus cells adsorbed 90.5% in the same time span. Temperature had no effect on adsorption by immobilized cells at levels of 2 and 10 g ml–1 Cd. However at higher concentrations, binding was enhanced as temperature increased.Z. ramigera beads were stable during all treatments and for prolonged periods of time (21 days). 相似文献
9.
Echeverrigaray S. Fracaro F. Andrade L.B. Biasio S. Atti-Serafini L. 《Plant Cell, Tissue and Organ Culture》2000,60(1):1-4
Murashige and Skoog (1962) medium supplemented with 1.0 to 4.5 M of BA and 1.0 M of NAA induced adventitious bud formation and shoot development in leaf explants of Roman Chamomile. A higher number of adventitious buds was observed at the proximal end of the explants. Plantlets were replicated and multiplied on MS medium supplemented with 2.25 M of BA and 0.6 M of IAA. Plantlets were rooted on MS medium supplemented with 0.5 M of IBA and successfully weaned in vivo. The plants grew to maturity with high uniformity and no morphological signs of somaclonal variation. 相似文献
10.
M. M. Diawara J. T. Trumble C. F. Quiros J. G. Millar 《Entomologia Experimentalis et Applicata》1992,64(2):125-133
Two Apium accessions were compared with the commercial cultivar Tall Utah 52–70R (A. graveolens [L.]) for resistance to Spodoptera exigua (Hübner)(Lepidoptera: Noctuidae). Oviposition rate was not significantly different between the three genotypes. In all accessions, eggs were usually placed on the upper half of the plants. Implications of this oviposition pattern on S. exigua management in celery are discussed. The wild species A. prostratum ssp prostratum var filiform (A230) showed a significantly higher resistance to S. exigua than 52–70R. The levels of carcinogenic and mutagenic linear furanocoumarins in the commercial cultivar 52–70R (1.41 g/g in the petioles; 5.85 g/g in the leaves) and in the plant accession A. nodiflorum (5.40 g/g in the petioles; 2.99 g/g in the leaves) were far below the concentration reported to produce acute contact dermatitis (18.0 g/g). The levels of furanocoumarins in A. prostratum petioles (186.14 g/g) and leaves (326.45 g/g) were 10 and 18 times higher, respectively, than the concentration known to cause contact dermatitis. However, resistance in A. prostratum was primarily due to non-preference and the linear furanocoumarins did not induce non-preference. Therefore, the resistance shown by this plant accession does not appear to be furanocoumarin-based and may be suitable for transfer to commercial celery for use in S. exigua management. 相似文献
11.
Cellular organization of the embryonic lobster heart 总被引:1,自引:0,他引:1
Summary The cellular organization of the embryonic heart of the lobster Homarus americanus was examined in 6-week and 6-month-old animals. The heart wall consists of an outer adventitial layer of fibroblast cells and an inner layer of transversely striated myocardial cells. Present in close association with the myocardium are cardiac neurons, hemocytes and so-called storage cells.Adjacent fibroblasts form fasciae adhaerentes and gap junctions. Adherent junctions also occur between fibroblasts and myocardial cells. Intercalated discs and differentiated membrane regions of close apposition (4 nm) occur between adjacent myocardial cells.The cardiac neurons form a ganglion that contains four small and five large somata. Regions of neuropil are present. Motor axons arising from the cardiac ganglion form neuromuscular synapses with the myocardial cells.The storage cells contain large inclusions and form gap junctions with the myocardial cells. They may supply nutritive material to the developing myocardium.The heart at 6 weeks is about 200 m long and 160 m wide. At 6 months, it is about 300 m long and 250 m wide. The myocardium at 6 weeks is one cell layer thick, and the cells are from 2–6 m in maximum width. At 6 months the myocardium is 2–4 cells thick, and the cells are from 6–12 m in width. Therefore, the myocardium grows by an increase in the number and size of the myocardial cells. 相似文献
12.
The activities and kinetics of the enzymes G6PDH (glucose-6-phosphate dehydrogenase) and 6PGDH (6-phosphogluconate dehydrogenase) from the mesophilic cyanobacterium Synechococcus 6307 and the thermophilic cyanobacterium Synechococcus 6716 are studied in relation to temperature. In Synechococcus 6307 the apparent K
m's are for G6PDH: 80M (substrate) and 20M (NADP+); for 6PGDH: 90M (substrate) and 25M (NADP+). In Synechococcus 6716 the apparent K
m's are for G6PDH: 550M (substrate) and 30M (NADP+); for 6PGDH: 40M (substrate) and 10M (NADP+). None of the K
m's is influenced by the growth temperature and only the K
m's of G6PDH for G6P are influenced by the assay temperature in both organisms. The idea that, in general, thermophilic enzymes possess a lower affinity for their substrates and co-enzymes than mesophilic enzymes is challenged.Although ATP, ribulose-1,5-bisphosphate, NADPH and pH can all influence the activities of G6PDH and 6PGDH to a certain extent (without any difference between the mesophilic and the thermophilic strain), they cannot be responsible for the total deactivation of the enzyme activities observed in the light, thus blocking the pentose phosphate pathway.Abbreviations G6PDH
glucose-6-phosphate, dehydrogenase
- 6PGDH
6-phosphogluconate dehydrogenase
- G6P
glucose-6-phosphate
- 6PG
6-phosphogluconate
- RUDP
ribulose-1,5-bisphosphate
- Tricine
N-Tris (hydroxymethyl)-methylglycine 相似文献
13.
Chris Selby W. Colin McRoberts John T. G. Hamilton Barbara M. R. Harvey 《Plant cell reports》1996,16(3-4):192-195
Head-space volatiles above embryogenicPicea sitchensis (Bong.) Carr. (Sitka spruce) tissues cultured in glass Petri dishes sealed with Parafilm M or cling-film, were captured on Tenax adsorption traps and analysed by gas chromatography / mass spectrometry. Each sealing system released a single major compound into the head-space; butylated hydroxytoluene from Parafilm M and 2-ethyl-1-hexanol from cling-film. After two weeks sealed under Parafilm M butylated hydroxytoluene accumulated to 1.1 g g–1 FW in tissues and subsequent somatic embryo maturation was prevented. When butylated hydroxytoluene was supplied via the head-space (100 g/250 ml flask) 0.5 g g–1 FW accumulated in tissues after two weeks and no somatic embryo maturation occurred. Potentially phytotoxic metabolites of butylated hydroxytoluene included a substituted stilbenequinone, butylated hydroxytoluene quinone methide and butylated hydroxytoluene dimer. 相似文献
14.
Summary Pollen tubes ofLilium longiflorum growingin vitro were treated for 1 h with inorganic lead (Pb) and with triethyl lead (TriEL) and studied by light and electron microscopy. Pb was considerably more toxic in relation to inhibition of pollen tube growth (EC50=6 M Pb) than was TriEL (EC50=60 M TriEL). On the other hand, at almost the entire concentration range tested (25-500 M) TriEL caused aberrant tubes and tube swellings. Pb did not cause tube swellings, even at highly growth-impairing concentrations. Pb (60 M) predominantly affected the ultrastructure of the growing cell walls without impairing the distribution of the cell organelles in the tube tips. In contrast, 50 and 100 M TriEL did not visibly influence cell wall ultrastructure but it severely damaged dictyosomes; 100 M TriEL also disturbed the original order of cell organelles in the tube tips. Cortical microtubules were selectively and completely destructed by TriEL at concentrations (50 M) where no effect on polar organization of the tube tips occurred but they remained unimpaired by 60 M Pb, indicating selective and effective interaction of TriEL with these cell organelles.Abbreviations EC50
effective lead concentration causing 50% inhibition of pollen tube growth
- MTs
microtubules
- Pb
inorganic lead
- TriAL
trialkyl lead
- TriEL
triethyl lead 相似文献
15.
Copper but not iron limitation increases astaxanthin production by Phaffia rhodozyma in a chemically defined medium 总被引:2,自引:0,他引:2
The influence of copper (0–32 M) and iron (0–108 M) on growth and astaxanthin production by Phaffia rhodozyma was studied. Copper below 3.2 M increased the astaxanthin content of the cells (from 220 to 287 g g–1) but at the expense of a slightly decreased growth (from 11.3 to 10.2 mg ml–1). In contrast, iron below 1 M decreased both the growth and astaxanthin content of the cells. Using copper limitation instead of toxic respiratory inhibitors to improve astaxanthin production has obvious advantages from the product quality, environmental and process operation points of view. 相似文献
16.
Leaf explants of Paphiopedilum phiIippinense hybrids (hybrid PH59 and PH60) directly formed adventitious shoots from wound regions within 1 month, when cultured on modified Murashige and Skoog medium (1/2-strength macro- and full-strength micro-elements) free of plant growth regulator in darkness. The combinations of 2,4-dichlorophenoxyacetic acid ((2,4-D) acid (0, 4.52 and 45.25 M) and 1-phenyl-3-(1,2,3-thiadiazol-5-yl)-urea (TDZ) (0, 0.45, 4.54 and 22.71 M) were used to test their effects on direct shoot bud formation from two types of explants (1.5-cm long intact leaf explants and 0.5-cm long leaf segment explants). In hybrid PH59, 4.54 M TDZ increased mean numbers of shoots per explant with leaf segment explants. In hybrid PH60, 4.52 M 2,4-D plus 0.45 M TDZ promoted direct shoot bud formation from leaf segment explants. In addition, three treatments (4.52 M 2,4-D, 22.71 M TDZ, 4.52 M 2,4-D plus 4.54 M TDZ) gave a higher response than control on mean numbers of shoots per explant with intact leaf explants. Healthy plantlets each with one to three roots were obtained from leaf-derived shoots after transfer onto a hormone-free medium for 22 months. These plantlets were acclimatized in a greenhouse and grew well with 100% survival rate. 相似文献
17.
Summary The filiform sperm of Littorina sitkana swims effectively in sea water and more viscous fluids, overcoming the problems of a non-uniform flagellar beat with an unusual mechanism, which involves three main events: (1) the sperm rotates anti-clockwise (looking from tail to head); then (2) stops rotating and stiffens itself to form a screw-shape, with the tail being held perpendicular to the middle piece, and finally; (3) reverses its rotation and propels itself forward in a clockwise spiral. The average velocity of sperm is approximately 185 ms with a rotational frequency of 24 revs. The mechanism of propulsion may involve two kinetic centers at opposite ends of the sperm, which coordinate their movements to produce anti-clockwise rotation, stationary twisting, or clockwise rotation, in a manner reminiscent of spirochaetes.
Littorina sperm also exhibit slower methods of propulsion including swimming backwards (tail first) at 18 m, and gliding at about 30 m.The adaptive significance of the rapid propulsion is not obvious, because Littorina copulate and fertilize internally and at each stage in the transfer there are external aids to sperm transport, such as ciliary action (oviduct) and muscular expulsion (bursa and seminal receptacle). The filiform shape, however, is well-adapted for long-term storage in the female body. These points are discussed. 相似文献
18.
The kinetics and specificity of GABA and taurine uptake were studied in the bullfrog sympathetic ganglia. GABA uptake system consisted of simple saturable component and taurine uptake system consisted of two saturable components exclusive of non-saturable influx. Taurine unaffected GABA uptake while GABA inhibited taurine uptake competitively with theK
i/Km ratio of 38. GABA (5.14 M) uptake was inhibited by -aminovaleric acid and slightly by 2,4-diaminobutyric acid (5 mM, each) among ten structural analogs. Taurine uptake under high-affinity conditions was most strongly suppressed by hypotaurine and -alanine competitively with theK
i/Km ratio of 1.0 and 1.9, respectively. Autoradiography showed that glial cells were heavily labeled by both [3H]GABA and [3H]taurine. These results suggest that GABA is transported by a highly specific carrier system distinct from the taurine carrier and that taurine, hypotaurine, and -alanine may share the same high-affinity carrier system in the glial cells of the bullfrog sympathetic ganglia. 相似文献
19.
John C. Afele Tissa Senaratna Bryan D. McKersie Praveen K. Saxena 《Plant cell reports》1992,11(5-6):299-303
Summary Somatic embryogenesis and plantlet formation have been achieved from cultured mature zygotic embryos of blue spruce (Picea pungens Engelman.). The effect of three basal media LP, LM, and BLG, all used at half-strength, was tested at the induction phase. LM medium induced somatic embryogenesis to a higher extent than LP whereas BLG did not produce any embryonal-suspensor mass representing stage 1 somatic embryos. The embryonal-suspensor mass was induced on a wide range of auxin/cytokinin ratios. However, media containing either 2 M NAA and 10 M BA, or 10 M NAA and 5 M BA produced somatic embryos that gave the highest frequency of plantlets. The level of ABA required in the maturation medium for somatic embryos to mature properly varied with the auxin/cytokinin levels in the induction medium on which the somatic embryos were derived. Inclusion of AgNO3 (10 – 100 M) in the induction medium reduced somatic embryogenesis and embryo conversion.Abbreviations NAA
naphthalene-acetic acid
- BA
N6-benzylaminopurine
- ABA
abscisic acid 相似文献
20.
W. A. Shipton 《Plant cell reports》1982,1(5):199-201
Callus development in Callistemon viminalis was readily achieved when axillary buds derived from nodal tissue were placed in a medium containing macro- and micro-nutrients, sucrose (0.06 M), inositol (300 M), nicotinic acid (20 M), pyridoxine hydrochloride (3 M), thiamine hydrochloride (2 M), riboflavin (10 M), cytokinins (5 M) and auxins (0.1 M). The presence of benzylaminopurine (5 M) and p-chlorophenoxyacetic acid (0.1 M) promoted the most vigorous callus development and sprout formation. Rooting of nodal material was rare but occurred readily following the transference of sprouts developed on callus to a basal medium containing sucrose and salts. Root initiation was stimulated, however, by the presence of auxins. Chlorophenoxyacetic acid while stimulating root initiation repressed root growth. Indole butyric acid stimulated both root initiation and shoot growth at concentrations of 0.005 to 0.1 M. The treatment of choice for rooting and shoot growth was the addition of indole butyric acid at a concentration of 0.01 M. 相似文献