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1.
Elizabeth A. Bray Satoshi Naito Nai-Sui Pan Edwin Anderson Philip Dubé Roger N. Beachy 《Planta》1987,172(3):364-370
Soybean (Glycine max (L.) Merr.) seeds contain the storage protein -conglycinin, encoded by a multigene family. -Conglycinin consists of three subunits; , , and . A genomic clone for a -subunit of -conglycinin has been characterized by restriction-enzyme mapping and hybrid selected in-vitro translation followed by immunoprecipitation. In order to determine the developmental regulation of this -subunit gene, its expression was studied in seeds of transgenic petunia (Petunia hybrida) and tobacco (Nicotiana tabacum L.) plants. The -subunit expressed in seeds of petunia and tobacco was recognized by anti--conglycinin serum at a relative molecular mass of 53 000, equivalent to that of the native protein. Separation of the petunia-seed proteins by isoelectric focusing followed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and immunoblot analysis showed that multiple isoelectric forms of the -subunit were produced. There was approximately a twofold variation in the accumulation of the -subunit protein in the mature seeds of transgenic petunia plants, each containing a single -subunit gene. However, the level of protein accumulation in mature seeds and the amount of -subunit mRNA in developing seeds was not correlated. Accumulation of the -subunit protein in transgenic seeds was less than the -subunit protein that accumulated in transgenic petunia seeds containing a single -subunit gene and less than the amount of the -subunit in mature soybean seeds which contain 8–13 -subunit genes. In transgenic tobacco plants, the accumulation of the -subunit protein in seeds was generally well correlated with the number of genes that were incorporated in the different transformants.Abbreviations kb
kilobase
- kDa
kilodalton
- Mr
relative molecular mass
- SDS-PAGE
sodium dodecyl sulfate polyacrylamide gel electrophoresis 相似文献
2.
As a precursor for the chemical synthesis of sialylated oligosaccharides, the trisaccharide glycoside Neu5Ac (2-8)Gal(1-4)GlcNAc(1-O)-pent-4-ene was synthesized starting from GlcNAc(1-O)-pent-4-ene, UDP-glucose andN-acetylneuraminic acid in a one pot reaction employing galactosyltransferase and (2-6)sialyl-transferase in a complete cofactor regeneration system.Abbreviations Neu5Ac
N-acetylneuraminic acid
- CMP-Neu5Ac
cytidine 5-monophosphosialate
- CMP
cytidine 5-monophosphate
- CDP
cytidine 5-diphosphate
- CTP
cytidine 5-triphosphate
- Gal
galactose
- GlcNAc
N-acetylglucosamine
- UDP
uridine 5-diphosphate
- UDP-Glc
uridine-5-diphosphoglucose
- UDP-Gal
uridine-5-diphosphogalactose
- PEP
phosphoenolpyruvate 相似文献
3.
Summary A set of transducing phages carrying varying lengths of the E. coli chromosome around the structural gene for initiation factor IF3 (infC) was derived from p2 which is known to cary, besides infC, the structural genes for the subunit of phenylalanyl-tRNA synthetase (pheS), the subunit of phenylalanyl-tRNA synthetase (phetT) and the structural gene for threonyl-tRNA synthetase (thrS). The E. coli coding content of these derived phages was analysed by genetic complementation of a set of mutants and by SDS-polyacrylamide gel analysis of the proteins synthesized in UV irradiated cells infected with these phages. The segregation pattern of the different genes among these derived phages indicates that the order of the genes is pheT-pheS-P12-(infC, thrS) where infC is probably between P12 and thrS. P12 is the structural gene of a 12,000 molecular weight unidentified protein.Abbreviations PRS (EC 6.1.1.20)
phenylalanyl-tRNA synthetase
- TRS (EC 6.1.1.3)
threonyl-tRNA synthetase
- IF3
Initiation factor IF3
- SDS
Sodium dodecyl sulfate
- PPR
pyrophosphate resistant
- PPS
pyrophosphate sensitive 相似文献
4.
Summary The histochemical demonstration of hetero--galactosidase (glucosidase) has been attempted in sections and zymograms of rabbit, monkey and human intestine and of rat kidney.The leakage of this enzyme from unfixed sections was prevented by the use of cold microtome sections adherent to semipermeable membranes. Methods with -D-glucosides and galactosides of 6-Br-2-naphthol (postincubation azocoupling with Fast Blue B as well as simultaneous azocoupling with hexazonium-p-rosaniline), of -naphthol (simultaneous azocoupling with hexazonium-p-rosaniline) and of 4-Cl-5-Br-3-indolyl (with ferricyanide, phenazonium methosulfate or nitro BT and without any oxidation agent) were used an evaluated concerning the specificity, localization ability and inhibition of enzyme activity. Pretreatment of sections with distilled water or saline and inhibition by p-Cl-mercuribenzoate, glucono- and galactono-lactones were used for the characterization of the demonstrated enzyme activity.6-Br-2-naphthyl--D-glucoside is the most specific substrate for hetero--galactosidase. It is not split by lactase and acid -galactosidase. Only lysosomal -glucosidase can interfere. Because the latter enzyme is membrane-bound the difference in color intensity between untreated and prewashed sections are due to hetero--galactosidase. Only localization on the cellular (not intracellular) level can be achieved, however.The simultaneous azocoupling method with -naphthyl--D-glucoside and hexazonium-p-rosaniline enables a very good localization of hetero--galactosidase in the rabbit intestine. Due to a great inhibition exerted by hexazonium-p-rosaniline on the enzyme activity the method is unsuitable for the detection of hetero--galactosidase in zymograms and in the human intestine. Interference of lactase (or lactase-phlorizine hydrolase complex) is to be considered. The lysosomal -glucosidase does not seem to interfere.Indigogenic methods are not sensitive either. With ferricyanide as an oxidation agent it was not possible to detect the activity of hetero--galactosidase in zymograms and in sections. This is possibly due to overoxidation of indigo. The same holds true for phenazonium methosulfate used for the processing of zymograms. However, it was possible to reveal the activity of hetero--galactosidase in sections of the rabbit and monkey intestine with phenazonium methosulfate as oxidation agent. Nitro BT enhanced the coloration both in zymograms and in sections. In the latter case diffusion artifacts cannot be prevented, however. The interference of lactase, lysosomal -galactosidase and possibly of lysosomal -glucosidase (depending on the glycoside used) is always to be considered.Hetero--galactosidase was localized in the cytoplasm (particularly in the supranuclear region) of differentiated enterocytes covering the villi of the rabbit (the highest activity), monkey and human (the lowest activity) intestine. In crypt enterocytes and in cells of Brunner's glands the activity was lower. The occurrence of a low activity of hetero--galactosidase in the brush border of enterocytes of the rabbit intestine was also demonstrated.A proximodistal gradient was observed in the rabbit and monkey intestine, the upper jejunum displaying the highest activity.In jejunal biopsies of patients with celiac sprue (in the acute stage of the disease) the activity of hetero--galactosidase was lowered. No changes of activity were observed in jejunal biopsies of patients with isolated deficiencies of lactase or sucrase.In the rat kidney the enzyme was demonstrated particularly in the cytoplasm of cells of proximal convoluted tubules. 相似文献
5.
D. Varjú 《Biological cybernetics》1976,25(1):17-26
The visual fixation response of the mealworm beetle Tenebrio molitor, elicited by black stripes upon a bright background is studied in an arena and by means of the Y-maze technique. In the arena the distribution n() of the beetle's angular position is measured at different distances from the centre, which is also the starting point. If the black stripe is narrow, the maximum of n() coincides with the centre of the stripe (centre-fixation Figure 1a). If one half of the panorama is black, the distribution n() has two maxima, which are near the borders between the black and white regions (edge-fixation Figure 1b). In the Y-maze experiments the beetle is tethered, but its head is free to move. The black stripes elicit turning tendencies F(), the strength of which depends upon the angular distance between the centre of the stripe and the animal's body axis. If the black stripe is narrow, the stable zero crossing of F() lies at =0, in agreement with the centre fixation in the arena (Fig. 3). If the stripe is 180° wide, two stable zero crossings are obtained near the border lines between the black and white regions, provided that the panorama is rotated around the animal with an angular velocity w larger than about 0.08°/s (Fig. 4). Below this value of w only one stable zero crossing at =0 exists (Fig. 6). Thus the tethered beetle's response underlies a transition between centre resp. edge fixation at a critical angular velocity of the drum. Some implications of this surprising phenomenon with respect to the mechanism of fixation and negative phototaxis are discussed but at present it is considered primarily a challenge for further investigation.Supported in part by Deutsche Forschungsgemeinschaft 相似文献
6.
Hallab Nadim J. Mikecz Katalin Vermes Csaba Skipor Anastasia Jacobs Joshua J. 《Molecular and cellular biochemistry》2001,222(1-2):127-136
Metal toxicity from sources such as orthopaedic implants was investigated in terms of immune system hyper-reactivity to metal implant alloy degradation products. Lymphocyte response to serum protein complexed with metal from implant alloy degradation was investigated in this in vitro study using primary human lymphocytes from healthy volunteers (n = 10). Cobalt chromium molybdenum alloy (CoCrMo, ASTM F75) and titanium alloy (Ti6Al4V, ASTM F136) beads (70 m) were incubated in agitated human serum at 37 degrees Celsius to simulate naturally occurring metal implant alloy degradation processes. Particulate free serum samples, which were incubated with metal, were then separated into molecular weight based fractions. The amounts of soluble Cr and Ti within each serum fraction were measured and correlated with lymphocyte proliferation response to the individual serum fractions. Lymphocytes from each subject were cultured with 11 autologous molecular weight based serum fractions either with or without added metal. Two molecular weight ranges of human serum proteins were associated with the binding of Cr and Ti from CoCrMo and Ti implant alloy degradation (at < 30 and 180–330 kDa). High molecular weight serum proteins ( 180 kDa) demonstrated greater lymphocyte reactivity when complexed with metal released from CoCrMo alloy and Ti alloy than with low (5–30 kDa) and midrange (30–77 kDa) serum proteins. When the amount of lymphocyte stimulation was normalized to both the moles of metal and the moles of protein within each fraction (MetalProtein Complex Reactivity Index, MPCRI), Cr from CoCrMo alloy degradation demonstrated approximately 10 fold greater reactivity than Ti in the higher molecular weight serum proteins ( 180–250 kDa). This in vitro study demonstrated a lymphocyte proliferative response to both CoCrMo and Ti alloy metalloprotein degradation products. This response was greatest when the metals were complexed with high molecular weight proteins, and with metalprotein complexes formed from CoCrMo alloy degradation. 相似文献
7.
Jan A. L. van Kan Matthieu H. A. J. Joosten Cornelia A. M. Wagemakers Grardy C. M. van den Berg-Velthuis Pierre J. G. M. de Wit 《Plant molecular biology》1992,20(3):513-527
Tomato leaves infected by the fungal pathogen Cladosporium fulvum contain several types of intracellular and extracellular pathogenesis-related (PR) proteins. Previously, we reported the purification and serological characterization of five extracellular PR proteins: P2, P4, P6, a chitinase and a -1,3-glucanase [22, 23]. Here we describe the purification of a basic intracellular 33 kDa -1,3-glucanase and the isolation and characterization of cDNA clones encoding the two extracellular P14 isomers P4 and P6, the extracellular acidic -1,3-glucanase and a basic 35 kDa -1,3-glucanase, different from the purified 33 kDa protein. Southern blot analysis demonstrated that tomato PR proteins are not encoded by large gene families, as is the case in tobacco. The number of genes corresponding to each protein was estimated to vary between one and three. A northern blot analysis indicated that the mRNAs for the extracellular PR proteins (P4, P6 and acidic -1,3-glucanase) accumulate to similar levels in compatible and incompatible tomato-C. fulvum interactions, although the maximum level of expression is reached much faster in the incompatible interaction. On the other hand, the mRNA for the basic 35 kDa -1,3-glucanase is induced rapidly to high levels in both interactions, but declines in time to background levels only in the incompatible interaction. The relevance of this difference in relation to plant defence is discussed. 相似文献
8.
Stefan Schillberg Martin Zimmermann Carl-Christian Emeis 《Applied microbiology and biotechnology》1991,35(2):242-246
Summary Rare-mating of closely related Saccharomyces cerevisiae and S. diastaticus strains led to the formation of different hybrids. Mating-type switching and chromosome losses could be observed by means of classical genetic analysis and pulsed field gel electrophoresis of intact chromosomes. The latter was facilitated by extensive chromosome length polymorphism in both strains. When crossing the two haploid strains S. cerevisiae 41 and S. diastaticus ATCC 28339 , two different types of hybrids occurred. Both types showed complete addition of both parental genomes, one a-status and the other -status. The -status could be explained by assuming a transient premutational lesion in MAT . Usually lesions are repaired after a mating event and the -mating type is restored. When crossing a diploid S. diastaticus strain, isogenic to the one previously mentioned, with the haploid S. cerevisiae strain, three different types of hybrids could be distinguished regarding their mating-types. It was possible to prove that the haploid S. diastaticus strain ATCC 28339 is disomic and the diploid hybrid, named 41ATCC-b, is trisomic for chromosome I. This could be shown by means of electrophoretic karyotyping of the hybrid and of the four single-spore cultures from one ascus of the hybrid. 相似文献
9.
Günter Wondrak 《Cell and tissue research》1966,76(2):287-294
Zusammenfassung Im Oberflächenepithel der Wegschnecke Arion empiricorum (Fér.) existieren drei Arten von exoepithelialen Schleimdrüsenzellen. Sie können auf Grund der Ultrastruktur, aber auch durch Heterochromasie bei Toluidinblaufärbung (bei verschiedenen pH-Werten), unterschieden werden. Der Typ der ventralen Sohlendrüse kommt in der Kriechsohle, der Schwanzdrüse, den Tentakeln, der Kopfhaut und in der vom Pneumostom ventrad ziehenden Flimmerrinne vor, der Typ der lateralen Sohlendrüse seitlich unter dem Sulcus lateralis. Die Manteldrüsen sind im übrigen Epithel zu finden.Die ventralen Sohlendrüsen sind durch ein eigenartig strukturiertes Ergastoplasma ausgezeichnet, die lateralen Sohlendrüsen besitzen ein Ergastoplasma, das auf Proteinbildung hinweist und die Manteldrüsen besitzen als Charakteristikum riesige Golgi-Vakuolen.
Herrn Professor L. Stockinger danke ich für Kritik und Ratschläge. 相似文献
Summary In the surface epithelium of the slug, Arion empiricorum (Fér.), there exist three types of exoepithelian slime-gland-cells. They can be distinguished on account of their ultrastructure as well as by the fact that they show heterochromatism at different pH-values after toluidine-blue-staining. The type of the ventrale Sohlendrüse occurs in the under surface of the foot, in the large slime-gland at the tail, in the tentacles, in the epidermis of the head and in the ciliated groove underneath the pneumostome, the type of the laterale Sohlendrüse on the sides underneath the sulcus lateralis. The Manteldrüsen are to be found in the other places of the epithelium.The ventrale Sohlendrüsen are characterized by their specific ultrastructure of the ergastoplasm, the laterale Sohlendrüsen by a type of ergastoplasm, which shows signs of protein-production, the Manteldrüsen however by containing huge Golgi-vacuoles.
Herrn Professor L. Stockinger danke ich für Kritik und Ratschläge. 相似文献
10.
Arabidopsis consensus intron sequences 总被引:7,自引:0,他引:7
We have analysed 998 Arabidopsis intron sequences in the EMBL database. All Arabidopsis introns to adhere to the :GU...AG: rule with the exception of 1% of introns with :GC at their 5 ends. Virtually all of the introns contained a putative branchpoint sequence (YUNAN) 18 to 60 nt upstream of the 3 splice site. Although a polypyrimidine tract was much less apparent than in vertebrate introns, the most common nucleotide in the region upstream of the 3 splice site was uridine. Consensus sequences for 5 and 3 splice sites and branchpoint sequences for Arabidopsis introns are presented. 相似文献
11.
The present investigation provides for the first time, unambiguous information on the occurrence of hypoxia-inducible factors (HIF-1 and HIF-1 proteins) in normoxia (Nx) and their interaction with hypoxia (Hx) and intracellular Fe2+ chelation in the rat carotid body (CB) glomus cells. HIF-1 bound to HIF-1 translocated into the nucleus is identified on the basis of immunohistochemistry and immunofluorescence. In Nx, a weak expression of HIF-1 was observed in CB glomus cells. However, exposure of CB and glomus cells to Hx (Po27 Torr) and Nx with ciclopirox olamine (CPX, 5 M) for 1 h showed a significant (P<0.001) increase in HIF-1 protein. The CBs and glomus cells exposed to Nx, Hx, and Nx with CPX showed a constant level of HIF-1 protein expression. HIF-1 subunit is continuously synthesized and degraded under normoxic conditions, while it accumulates rapidly following exposure to low oxygen tensions. Hydroxylation of HIF-1 by prolyl hydroxylase for proteasomal degradation was dependent on iron, 2-oxoglutarate, and oxygen concentration. The intracellular iron that acts as a cofactor for prolyl hydroxylase activity belongs to the labile iron pool and can be easily chelated. Thus, chelation of intracellular labile iron by CPX in Nx significantly increased HIF-1 in CB glomus cells. Thus, the results are consistent with the hypothesis that HIF-1 which is present in the glomus cells translocates to the nucleus during exposure to Hx and to CPX in Nx. 相似文献
12.
Summary The nucleotide sequence of cytoplasmic 5S ribosomal RNA fromEuglena gracilis has been determined to be: G-
A
C
-G-U-A-C-G-G-C-C-A-U-A-C-U-A-C-C-G-G-G-A-A-U-A-C-A-C-C-U-G-A-A-C-C-C-G--U-C-G-A-U-U-U-C-A-G-A-A-G-U-U-A-A-G-C-C-G-G-G-U-U-A-G-G-C-C-C-A-G-U-U-A-G-U-A-C-U-G-A-G-U-G-G-G-C-G-A-C-C-A-C-U-U-G-G-G-A-A-C-A-C-U-G-G-G-U-G-C-U-G-U-A-C-G-C-U-Up. This RNA is 119 nucleotides long and the sequence of a probable tRNA-binding site is GAUU (position 41–44 from the 5-terminus), which is the same as that of a trypanosoma species,Crithidia fasci-culata. TheEuglena 5S rRNA has a pseudouridine residue at position 38 and 3-terminus is phosphorylated. The 5S rRNA sequence ofEuglena resembles those of several other protozoa and higher animals rather than plants.On leave from Department of Zoology, Hiroshima University, Hiroshima, Japan 相似文献
13.
C. C. Wong K. Y. Lam K. W. Chiu 《Journal of comparative physiology. B, Biochemical, systemic, and environmental physiology》1993,163(3):212-218
The extrathyroidal conversion of thyroxine to triiodothyronine in the snake, Elaphe taeniura, has been determined in vitro. The liver, kidney and pancreas are important organs showing significant 5-deiodinase activity. The pancreas has a higher conversion rate (18.5±3.58 pmol·min-1·mg protein-1) than other vertebrate tissues that have been studied. The 5-deiodinase activity is dependent on substrate (thyroxine) concentration, cofactor, i.e. dithioerythritol concentration, temperature, duration of incubation and pH. It is sensitive to iopanoic acid, propylthiouracil, salicylate and propranolol. It is also indicative that the 5-deiodinase activity increased and decreased, respectively, in snakes with experimentally induced hyper- and hypo-thyroidism. These characteristics suggest that snake 5-deiodinase is similar to that of mammals, probably of type I category.Abbreviations ANOVA
analysis of variance
- BSA
bovine serum albumin
- BW
body weight
- cpm
counts per minute
- 5D
5-deiodinase
- DTE
dithioerythritol
- EDTA
ethylenediamine tetraacetate
- IOP
iopanoic acid
-
K
m
Michaelis-Menten constant
- L/D
Light/Dark
- MW
molecular weight
- NRS
normal rabbit serum
- PEG
polyethylene glycol
- %B
percentage of added label found in the pellet
- PTU
propylthiouracil
- RIA
radioimmunoassay
- rT3
3,5,5-triiodothyronine
- SPSS
Statistical Package for the Social Sciences
- T3
3,5,3-triiodothyronine
- T4
thyroxine
- TRIS
Tris (hydroxymethyl) aminomethane
- Tx
thyroidectomized
-
V
max
maximum velocity of enzyme reaction 相似文献
14.
Control of lectins in Triticum aestivum and Aegilops umbellulata by homoeologous group 1 chromosomes
H. M. Stinissen W. J. Peumans C. N. Law P. I. Payne 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》1983,67(1):53-58
Summary Each of the three genomes in hexaploid wheat controls the expression of a specific lectin in the embryo. The chromosomes which control their synthesis were determined using nullisomic-tetrasomic and inter-varietal chromosome substitution lines of Chinese Spring. All three wheat lectins were shown to be controlled by the homoeologous group 1 chromosomes. Using ditelosomic lines of Chinese Spring the lectin genes could be localized on the long arms of chromosomes 1A and 1D. Inter-specific addition and substitution lines of Aegilops umbellulata chromosomes to Chinese Spring indicated that chromosome 1U, which is homoeologous to the group 1 chromosomes of wheat, controls lectin synthesis. 相似文献
15.
B. Koukalová J. Reich R. Matyášek V. Kuhrová M. Bezděk 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》1989,78(1):77-80
Summary HRS60.1, a monomer unit (184 bp) of a highly repeated nuclear DNA sequence of Nicotiana tabacum, has been cloned and sequenced. Following BamHI digestion of tobacco DNA, Southern hybridization with HRS60.1 revealed a ladder of hybridization bands corresponding to multiples of the basic monomer unit. If the tobacco DNA was digested with restriction endonucleases which have no target site in HRS60.1, the larger part of DNA homologous to HRS60.1 remained as uncleaved relic DNA. These results suggest a tandem arrangement of this DNA repeat unit. Four other clones of tobacco nuclear DNA cross-hybridized with HRS60.1, thus forming a HRS60-family. Sequencing their inserts has shown their strong mutual homology. HRS60-family comprised about 2% of the nuclear genome of N. tabacum. Computer comparisons with other tandem plant-repeated DNA sequences could not detect any other homologous sequence. 相似文献
16.
Expression of too many co-dominant major histocompatibility complex (MHC) alleles is thought to be detrimental to proper functioning of the immune system. Polyploidy of the genome will increase the number of expressed MHC genes unless they are prone to a silencing mechanism. In polyploid Xenopus species, the number of MHC class I and II genes has been physically reduced, as it does not increase with higher ploidy genomes. In the zebrafish some class IIB loci have been silenced, as only two genomically bona fide loci, DAA/DAB and DEA/DEB, have been described. Earlier studies indicated a reduction in the number of genomic and expressed class II MHC genes in a hexaploid African large barb. This prompted us to study the number of MHC genes present in the genome of an African large barb individual (Barbus intermedius) in relation to those expressed, adopting the following strategy. Full-length cDNA sequences were generated from mRNA and compared with partial genomic class Ia and II sequences generated by PCR using the same primer set. In addition, we performed Southern hybridizations to obtain a verification of the number of class I and IIB genes. Our study revealed three 2-microglobulin, five class Ia, four class IIA, and four class IIB genes at the genomic level, which were shown to be expressed in the hexaploid barb individual. The class Ia and class II data indicate that the ploidy status does not correlate with the presence and expression of these MHC genes. 相似文献
17.
G. R. N. Jones 《Histochemistry and cell biology》1969,18(2):164-167
Summary The syntheses of 4,4-biphenyl tetrazonium chloride monohydrate, of 1,1-di-(3-nitrophenyl)-3,3-dimethyl-5,5-(4,4-biphenylene)-diformazan, and of yellow tetrazolium [2,2-di-(3-nitrophenyl)-5,5-dimethyl-3,3-(4,4-biphenylene)-ditetrazolium chloride] are described. Solutions of the pure formazan in pyridine absorb visible light maximally at 455 nm; 455 is 54,050. Yellow tetrazolium has been specifically designed to meet the requirement of a new technique in quantitative cytochemistry, which involves the consecutive use of two bistetrazolium salts on the same tissue section.I thank Professor L. Young of St. Thomas's Hospital Medical School and Professor C. Long of the Royal College of Surgeons for their interest and encouragement. I am greatly indebted to a large number of friends and colleagues for helpful discussion, and to Dr. A. Deavin and Miss A. Banks for exploratory experiments which involved column chromatography. Microanalyses were carried out by Mr. G. S. Crouch at the London School of Pharmacy. 相似文献
18.
Meiosis in Coprinus 总被引:7,自引:0,他引:7
Chromosome pairing takes two steps: members of the homologous pair become aligned first and then zip up throughout their length. Initial contact may begin from one end or from both ends of the chromosomes. Prom late paehytene to diplotene, the chromosomes are somewhat elongated and exhibit lampbrush characteristics. This is followed by a diffuse stage in which the chromosomes are most indistinct. The centrosome divides at this time. The chromosome numbers are as follows: Coprinus lagopus, n=12; C. micaceus, n=12, C. comatus, n=14; and C. atramentarius, n=16. 相似文献
19.
Flax anther culture: effect of genotype,cold treatment and media 总被引:2,自引:0,他引:2
Bohuš Obert Beata Dedičová Andrea Hricová Jozef šamaj Anna Pret'ová 《Plant Cell, Tissue and Organ Culture》2004,79(2):233-238
We report on screening of wide range of flax cultivars for androgenic response and on testing of induction conditions for flax (Linum usitatissimum L.) anther culture and plant regeneration. Anthers were cultured on four different media: Mo, N6, MS and N&N supplemented with various combinations of growth regulators. The induction of callus formation from cultured anthers was the highest on N6 (with cultivar PR FGL 77 – 12 %) and N&N media (with cultivar Carolin – 2.8 %), preferentially after cold pretreatment (7days at 8 °C). Shoots were formed on calli derived from the microspores inside the cultured anthers on media N&N and N6 supplemented with 1mgl–1 zeatin or 1mgl–1BAP + 1mgl–1NAA, respectively and elongated on MS medium supplemented with 2mgl–1 zeatin. The highest number of shoots (120) was observed with cultivar Red Wing. Shoots were rooted on MS medium supplemented with 2mgl–1IAA. Our experiments resulted in total in 62 % anther response and 155 plants regenerated and transferred into soil. 相似文献
20.
Seishi Takahashi 《Molecular & general genetics : MGG》1975,142(2):137-153
Summary Intermediates of DNA replication in the second half of the latent period after phage infection were isolated and investigated in the electron microscope by denaturation mapping. The isolated replicative froms (RF) are predominantly single branched circular DNA. The starting points of replication in these lariat molecules located at the same region as in the first round DNA replication. About 60% of the RF replicate from left to right and the other 40% replicate in the reverse direction. The free ends of the tails are located at many sites on the genome. Replicating circles with a linear DNA tail longer than one unit length of genome represent about 30% of the replicating molecules. These long linear tails (concatemers) produced by the rolling-circle (Gilbert and Dressler, 1968; Eisen et al., 1968; Skalka et al., 1972; Takahashi, 1974) are one of the best candidates for a precursor DNA of progeny phage. 相似文献