共查询到20条相似文献,搜索用时 62 毫秒
1.
Craig A. Cooney 《Molecular biotechnology》1994,2(2):119-127
High resolution DNA size markers are described for pulsed field gel electrophoresis (PFGE). These markers provide resolution of 10–20 kbp over a size range from 10 kbp to more than 400 kbp and are produced by partial restriction digestion of lambda phage DNA concatemers (λ ladder). High resolution markers extending to over 400 kbp are made by partial restriction digestion of λ ladder embedded in agarose. Detailed methods are described for marker production and for DNA separation by contour-clamped homogeneous electric field (CHEF) electrophoresis. These markers and methods are useful for a variety of high resolution DNA mapping by PFGE. 相似文献
2.
Ch. Sultan J. M. Lobaccaro S. Lumbroso S. Missov Ch. Belon M. Bost R. Dumas 《Andrologie》1994,4(3):283-287
Klinfelter syndrome was first described in adult males with gynecomastia, azoospermia and hypergonadotropic hypogonadism. Children with the 47, XXY karyotype demonstrate few clinical findings so Klinefelter syndrome is rarely diagnosed until adult life. Besides children who have been diagnosed during prenatal genetic testing, in infancy a male with 47, XXY (or variants: 46, XY-47, XXY; 48, XXXY; 48, XXYY, 49, XXXXY) may be found while undergoing evaluation of micropenis, hypospadias, cryptorchidism or facial anomalies. The older child may present with learning disabilities, behavior disorders or tall stature. At the time of puberty, the clinical picture includes small testes, gynecomastia and an eunuchoid habitus. Early diagnosis of Klinefelter syndrome must be performed since it has been demonstrated that early treatment with androgens may ameliorate many aspects of the clinical symptoms and attenuate or prevent behavioral and psychiatric disorders associated with 47, XXY males. 相似文献
3.
DNA topoisomeraseI isolated from the lower eukaryoteNeurospora crassa mitochondria was characterized. Molar mass of the enzyme in the native state is 120 kDa and 60–65 kDa when denatured. The pH optimum of the enzyme is 7.8 and the KCl optimum concentration is 40 mmol/L. This topoisomerase is independent of ATP and Mg2+. N-Ethylmaleimide, 4-chloromercuribenzoate, SDS, guanidinium chloride, polyethylene glycol, heparin and ethidium bromide inhibit its activity, while novobiocin, nalidixic acid, Triton X-100 and chloroquine do not. Polyamines, and histone, H1 stimulate the topoisomerase activity. We classify this DNA topoisomerase as typeI and eukaryotic. Conversion of the topoisomerase to a nonspecific endonuclease at increased temperature is proposed. 相似文献
4.
Santos Susín Joaquin Abián M. Luisa Peleato Francisco Sánchez-Baeza Anunciación Abadía Emilio Gelpi Javier Abadía 《Planta》1994,193(4):514-519
The characteristics of flavin excretion from iron-deficient sugar-beet roots have been studied. Roots from iron-deficient sugar beet excreted flavins when plants were allowed to decrease the pH of the nutrient solution, but not when plants were grown in nutrient solutions buffered at high pH. As shown by reversed-phase high-performance liquid chromatography, the two major flavins whose excretion was induced by iron deficiency were different from riboflavin, FMN and FAD. These flavins have been identified as riboflavin 3′-sulfate and riboflavin 5′-sulfate by electrospray-mass spectrometry, inductively coupled plasma emission spectroscopy, infrared spectrometry and1H-nuclear magnetic resonance. We have characterized the time courses of accumulation of the different flavins in the nutrient solution and considered several possible roles for flavin excretion in iron acquisition. 相似文献
5.
Meiotic investigation is rare in male infertility. Now, some mutations affecting spermatogenesis exhibit characteristic cytogenetic figures, whereas testicular histology does not show specific aspects of this pathology. In male infertility with abnormal somatic caryotype, the aim of meiotic survey is to find the mechanisms inducing spermatogenic failure, and thus to lead to a better understanding of normal spermatogenesis. In addition to cytogenetic techniques, meiosis is also investigated by electron microscopy and molecular biology. Also, we think that a larger place must be grant to meiotic study in male infertility evaluation when the indication of testicular histopathology was settled. 相似文献
6.
Growing numbers of HIV seronegative women want to have children with HIV infected partners by artificial insemination. The most sensitive assays for showing the presence of the virus are the coculture method and the DNA-PCR that are able to detect proviral load. HIV is detected from non spermatozoal mononuclear cells, seminal fluid but it was not found in spermatozoa fraction. But we know, by in vitro studies, that HIV can bound to and enter spermatozoa. Thus artificial insemination between HIV seropositive man and seronegative woman lead to a risk of contamination even with purified spermatozoa. Today, any virological assay is able to affirm that specimen is not infectious. 相似文献
7.
S. G. Chankova A. D. Mehandjiev E. D. Blagoeva S. N. Ptitsina S. A. Sergeeva V. A. Shevchenko 《Biologia Plantarum》1994,36(4):583-589
This paper compares the repair of DNA single strand breaks (ssb) induced by γ-radiation in two strains ofChlamydomonas reinhardtii (137C/+/ and UVS-I) and three lines ofPisum sativum (NN 131, 198, 140) differing in the degree of radioresistance. DNA ssb in cells exposed to γ-rays (50, 100, 200, 500 Gy) were measured by electrophoresis and alkaline unwinding method with subsequent chromatography on hydroxyapatite immediately after irradiation and after 30 min of post-irradiation incubation at 25°C. An increase of double-strand DNA (in%) was found in cells after 30 min post-irradiation incubation.C. reinhardtii strains displayed an equal level of DNA degradation and repair efficiency in the DNA single strand breaks. The radioresistant line N 198 ofP. sativum is characterized by a lower level of induced DNA ssb and higher efficiency of repair of these breaks as compared with less radioresistant lines NN 131 and 140. 相似文献
8.
Effects of inorganic arsenicals on DNA synthesis in unsensitized human blood lymphocytes were biphasic: The chemicals at very low concentrations enhanced DNA synthesis, whereas higher concentrations inhibited DNA synthesis. The concentrations of arsenicals at which the maximum stimulating effect was found were 1×10?5 M, 1×10?6 or 2×10?6 M, and 0.8×10?6 or 1×10?6 M for sodium arsenite exposure of 1 h, 3 d, and 6 d, respectively; for sodium arsenate, 1× 10?5 M, 1×10?5 M, and 2×10?6 or 5×10?6 M, respectively. Arsenicals must be present for the entire 6-d culture period to produce maximum stimulation of DNA synthesis in human lymphocytes. The longer exposure of the lymphocytes to arsenicals, the lower the concentrations of arsenicals at which the maximum stimulating effect on DNA synthesis was found. Stimulating effect of trivalent arsenic (sodium arsenite) on DNA synthesis was stronger than pentavalent arsenic (sodium arsenate), and the stronger the effect of trivalent arsenic than pentavalent, the longer exposure of the cells to the chemicals. Both sodium arsenite and sodium arsenate stimulated DNA synthesis in human lymphocytes to a lower degree than phytohemagglutinin (PHA). 相似文献
9.
M. L. Cordero J. G. Ortiz G. Santiago A. Negrón J. A. Moreira 《Molecular neurobiology》1994,9(1-3):253-258
The C57BL/10 SPS/sps mouse mutant are audiogenic seizure-susceptible. The enzymatic activities of glutamate decarboxylase (GAD), GABA aminotransferase (GABA-T), alanine aminotransferase (ALA-T), aspartate aminotransferase (ASP-T), and glutamate dehydrogenase (GDH) of whole brain supernatant are significantly reduced in these epileptic mice. GABA uptake is decreased in cortex, midbrain, and pons medulla. Previous studies showed the presence of two sodium-dependent GLU uptake systems in normal (SPS/SPS) mice. Glutamate Umax by System 1 is significantly decreased in these mice, whereas the Umax value for System 2 is significantly increased in the epileptic mice. 相似文献
10.
Berthold Heinze 《Molecular biotechnology》1994,1(3):307-310
As opposed to standard polymerase chain reaction (PCR) using specific primers, genome analysis involving short random primers, for example RAPD, may yield inconsistent results if crude plant DNA preparations are used as the template. When RNase A, a thermostable enzyme, was added to such reactions, highly repeatable banding patterns were obtained from crude plant DNA, thus speeding up analyses substantially. 相似文献
11.
R. Mieusset 《Andrologie》1994,4(2):190-196
A history of cryptorchidism is the only risk factor for testicular cancer that can be considered unequivocally established. The rate of cryptorchidism at age 3 months appears to have increased over the 30 years from 1.7% to 3.2%. From a review of the literature, the overall proportion of testicular cancer patients with a history of cryptorchidism is approximately 10%. Case-control studies indicate that the relative risks of testicular cancer associated with a history of cryptorchidism are about 6. Prevalence of testicular cancer in patients with a history of cryptorchidism could range between 2% and 3%, as reported in studies from North European Countries. Orchidopexy itself or age at orchidopexy seem to have no effect on the subsequent risk of testicular cancer; however, data from the literature are somewhat discrepant. But orchidopexy does seem to influence the histologic type of malignancy, with a lower frequency of seminoma. The developement of non invasive techniques is badly needed to allow population screening for testicular cancer. 相似文献
12.
Eric Vendrely 《Andrologie》1994,4(3):296-302
Klinefelter's syndrome is characterised by azoospermia, gynecomastia and hypogonadotropic hypogonadism. The testes are reduced in volume. Microscopically, seminiferous tubules show a reduced diameter and a thickening of peritubular sheath. The seminiferous epithelium contains Sertoli cells with a clear typical nucleus and a heterogeneous nucleolus. Usually there are no germ cells. When present they degenerate at the spermatocyte stage. Very few achieve a complete maturation until the spermatozoon form. The interstitial gland appears relatively hypertrophied, due to the decrease in volume in the other components of the testis. Sometimes Leydig cells display an adenomatous morphology. Therefore the steroidogenic function is impaired. Azoospermia is a major event in Klinefelter's syndrome but sometimes restricted to severe oligozoospermia. In that cases, fertility may be somewhat preserved, and the caryotype usually reveals a mosaicism, 47,XY/47,XXY with a better prognosis than in pure syndrome. 相似文献
13.
Polymorphism in two malarial antigens, merozoite surface antigen-1 (MSA-1) and ring erythrocyte surface antigen (RESA), has been characterized in four different Indian strains ofPlasmodium falciparum. The Indian strains were obtained from two malaria endemic regions of India, viz. Surat (Gujarat) and Delhi, and established in culture. Monoclonal and polyclonal antibodies raised against different domains of these antigens were used in the study. In MSA-1 a novel intragenic crossover was detected in the central conserved domain in two of the Indian strains. The repeat domain of RESA was found to be absent in the two strains ofP. falciparum isolated from Surat. These differences in immunoreactivity have been extended to the DNA level by appropriate PCR studies. MSA-1 and RESA are candidate vaccine antigens and these diversities will have an important bearing on the design of a suitable malaria vaccine. 相似文献
14.
Michele Ramsay 《Molecular biotechnology》1994,1(2):181-201
Yeast artificial chromosome (YAC) cloning systems enable the cloning of DNA stretches of 50 to well over 2000 kb. This makes it possible to study large intact regions of DNA in detail, by restriction mapping the YAC to produce a physical map and by examining the YAC for coding sequences or genes. YACs are important for their ability to clone the complete sequences of large genes or gene complexes that exceed the size limit for cloning in conventional bacterial cloning vectors like plasmids (up to 10 kb), bacteriophage (15 kb), and cosmids (50 kb). A major advantage of cloning in yeast, a eukaryotc. is that many sequences that are unstable, underrepresented, or absent when cloned into prokaryotic systems, remain stable and intact in YAC clones. It is possible to reinlroduce YACs intact into mammalian cells where the introduced mammalian genes are expressed and used to study the functions of genes in the context of flanking sequences. The correct prolein processing mechanisms are present in the mammalian cells to ensure that a viable protein product is produced. 相似文献
15.
Spermatogenesis impairment is frequently associated with autosomal rearrangements. A meiotic study was performed on testicular biopsies of men ascertained through primary fertility and found to be heterozygous for reciprocal translocation, Robertsonian translocations, inversions and extra chromosomes. Pairing failure at meiosis as well as intimate associations between rearranged autosomes and the XY bivalent have been discussed as a cause of gametogenic arrest. 相似文献
16.
M. M. F. Mansour 《Biologia Plantarum》1994,36(3):429-434
10-d-old wheat seedlings were grown hydroponically in presence and absence of 100 mM NaCl for 7 d. Salt stress decreased growth of shoots and roots of both cultivars; fresh mass of sensitive cultivar being more affected. NaCl increased membrane permeability to urea, methylurea and ethylurea and decreased membrane partiality in root cortex cells of sensitive cultivar. Neither parameter changed by NaCl in resistant cultivar. NaCl treatment decreased water permeability and osmotic potential in both cultivars; sensitive cultivar was more affected. The results extends our previous data that cell membrane properties are different in salt sensitive and resistant genotypes and so cell permeability could be a potential trait indicating salt tolerance. 相似文献
17.
When stem explants of kale (Brassica oleracea L. var.medullosa), containing pith parenchyma and a strip of vascular tissue, were cultured on simple sucrose medium, a hormone-like factor was transported from the vascular tissue to the adjacent pith, where it stimulated accumulation of starch. Similarly, up to a sevenfold increase of starch content in explants could be induced by cytokinins added to the culture medium. The relative stimulatory effect of several cytokinins (5×10?6 M) and hormone-like product of vascular tissue (HPVT) in a typical experiment were: control (1.0), trans-zeatin (6.7), HPVT (6.2), N6-[2-isopentenyl]adenine (5.4), transzeatin riboside (5.2), N6-[2-isopentenyl]adenosine (5.4), kinetin (3.6), 6-benzylaminopurine (3.5), and adenine (2.1). Concentration of endogenous cytokinins was determined using ELISA (trans-zeatin, N6-[2-isopentenyl]adenine and their ribosides) andAmaranthus bioassay (total cytokinins). No effect of vascular tissue on the level of endogenous cytokinins in explants was found. The results support the conclusions of previous experiments that the HPVT stimulating starch accumulation is not a cytokinin. 相似文献
18.
The role of seed coats in seed viability 总被引:3,自引:0,他引:3
Yasseen Mohamed-Yasseen Sheryl A. Barringer Walter E. Splittstoesser Suzanne Costanza 《The Botanical review》1994,60(4):426-439
The seed coat is the seed’s primary defense against adverse environmental conditions. A hard seed coat protects the seed not only from mechanical stress but also from microorganism invasion and from temperature and humidity fluctuations during storage. Phenolic compounds in the seed coat contribute to seed hardness and inhibition of microorganism growth. During germination, the seed coat protects the seed from hydration stress and electrolyte leakage. 相似文献
19.
Three anionic peroxidases (EC 1.11.1.7), named Prx1, 2, and 3, which are rapidly accumulated in cucumber (Cucumis sativus L., cv. Laura) reacting hypersensitively to tobacco necrosis virus, were purified to homogeneity. The three enzymes had an isoelectric point about 4.3, and the relative molecular masses of Prx1, 2, and 3 estimated by SDS-PAGE were 40 700, 38 000, and 37 100, respectively. These peroxidases had a similar pH stability, but differed in their specific activity, pH optimum, and thermal stability By Ouchterlony double diffusion tests with antisera raised against the three purified enzymes, close serological relationships have been demonstrated between the three peroxidases. 相似文献
20.
O. H. E. Hammouda 《Biologia Plantarum》1994,36(2):229-236
Paraquat (methylviologen) at concentrations above 0.05 mM inhibited the growth of photoautotrophic cyanobacteriumGleeocapsa sp. in axenic cultures. The growth rate was not affected by concentrations of 0.01 mM or less. This concentration resulted after a lag period in a moderate increase in superoxide dismutase level. After removal of paraquat, the cyanobacterium continued to generate higher levels of superoxide dismutase. There was a lag period of one hour before resumption of normal enzyme activity. Addition of puromycin at concentration of 0.5 mg cm?3 had no effect on cell survival, but greatly enhanced the sensitivity of the culture to the toxicity of paraquat. The data showed an increase of SOD activity by temperatures above the normal growth temperature level. However, this increase was suppressed by chloramphenicol which revealed that the induction of superoxide dismutase by high temperatures was associated withde novo protein synthesis. 相似文献