共查询到20条相似文献,搜索用时 15 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.
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
3.
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
4.
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
5.
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
6.
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
7.
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
8.
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
9.
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
10.
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
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.
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
13.
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
14.
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
15.
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
16.
A salt mixture resistant (SMR) cell line ofVigna radiata (L.) Wilczek was isolated by selection on agar solidified PC-L2 medium supplemented with NaCl, KCl and Na2SO4 (8∶1∶1) equimolar to 300 mol m?3 NaCl, a concentration inhibitory to the wild-type non-selected cells (salt mixture sensitive, SMS). This line retained its resistance after subculture for 3 passages (3 months) on normal medium. The SMR line grew significantly better than SMS line at all the levels of salts, though less in saline medium than the SMR on normal medium. The growth of SMR line was significantly higher than that of SMS line under KCl stress. However, both the lines responded similarly to Na2SO4 at a concentration higher than 100 mol m?3. The SMR line was found to be more sensitive to NaCl than SMS line. The SMR line under salt mixture stress maintained lower levels of Na+ and higher levels of K+ than SMS line. The SMR line failed to regenerate shoots, although rhizogenesis was observed on PC-L2 medium containing salt mixture (300 mol m?3). 相似文献
17.
J. Stejskal 《Biologia Plantarum》1994,36(3):359-364
Two staining methods for aspartate aminotransferase were compared after electrophoretic resolution of its isozymes in polyacrylamide gels. The first one uses L-aspartic acid and Fast Blue BB salt (classical method), the second uses L-cysteine sulfinic acid and a redox system with phenazine methosulfate and 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2H-tetrazolium bromide. The seeds of pea, horse bean and soybean were used as a model plant source of the enzyme. The staining method with L-cysteine sulfinic acid is very reliable and more sensitive than the Fast Blue BB method and allows detection at very low isozyme activities in the gel. 相似文献
18.
Elisabeth Dussaix 《Andrologie》1994,4(4):414-420
At least two members of the herpesviridae family, the human cytomegaloviruses (HCMV) and the herpes simplex viruses (HSV) can be found in human semen; but the role of the germ cells in the sexual transmission of these viruses is not clear. In teenagers and the adult population, sexual contact is considered to be a common mode of HCMV acquisition. HCMV was isolated from semen specimens of 33 % of HIV infected homosexual men, 20 % of HIV uninfected homosexual men and only of 2,4 % of healthy heterosexual men. Virus particles could be demonstrated by electron microscopy examination inside the sperm head as well as in the seminal liquid but at present, there is no direct evidence either for HCMV transmission via fertilization or for induction of fetal anomalies by vertical transmission. Transmission via donor semen is undoubtedly possible although not yet described and it may be safer to employ HCMV seronegative donor for all recipients, regardless of the recipient’s serologic status. The development of serologic assays that differentiate the two serotypes of HSV demonstrated the worldwide distribution of genital HSV-2 which has been increasing in many developed countries throughout the last two decades. In several studies, HSV-2 has been recovered from the male reproductive tract, specifically the prostate, seminal vesicles, vasa and testes, in the absence of active lesions. In contrast, tissue cultures of semen sampled during lesion-free periods had been uniformly negative for HSV. However recently, one report documents transmission of HSV-2 via therapeutic donor insemination and illustres the fact that semen might be a vehicle of transmission of HSV. At present, it is adequate to recommend that men, with a history of a recurrent genital herpes or who have a sexual partner with such a history, are excluded as potential semen donors. Further, in the near future, with the increase of asymptomatic viral shedding from the genital tract, the presence of HSV-2 antibody could be added as an exclusion criterion. 相似文献
19.
The semen results from the mixture on ejaculation of various secretions from the testicle, the genital tract and the adnex glands. It consists on a cellular phase: spermatozoa and a liquidian phase: the seminal plasma. The spermogram is the first exam to make in order to set diagnosis of male infertility. It is completed with a biochemical study of the semen to find an excretory origin to infertility. In this work, we have studied the frequences of prostatic, vesicular and epididymious anomalys, through dosage of their markers in the semen, in 146 males consulting for infertility and eventual relationships between these markers and the characteristics of the spermogram. We found out that the prostate is the most hurt portion of the genital tract in infertile males and presents a dysfunctioning in 32,26% of cases, most often resulting in an inflammatory states of this gland. The epididymious obstruction is detected in 35% of azoospermia cases. In all the cases, we found out significant statistical correlation between the semen volume and the activity of alpha 1–4 glucosidase and also the pH of the semen and the seminal citric acid. For patients having a high leucospermia we didn’t find any relationship between the leucocytes rate in the semen and the different biochemical markers. If the seminal fructose rate has no effect on the initial mobility of spermatozoa, it has a statistically significant effect on their survival. In fact, the diminution of seminal fructose coincides with a bad survival of spermatozoa, which shows the importance of this spermatic substrate on the maintaining of spermatozoa mobility. 相似文献
20.
Leopold J. Anghileri Philippe Maincent Alfredo Córdova-Martínez Jesús F. Escanero 《Biological trace element research》1994,40(1):83-88
Ferric lactate is known to modify Ca2+ uptake by the cells. To enlighten the role of protein and ATP in this phenomenon, iron transfer from ferric lactate to albumin and adenosine polyphosphates was determined by electrophoresis. The order of iron affinity was ATP>ADP>AMP for the polyphosphates, and albumin does not compete for iron binding with the polyphosphates. The iron transfer to ATP was also observed in vivo by adsorption chromatography of the adenosine polyphosphates fraction from blood plasma of mice injected with ferric lactate plus ATP. In vitro iron and calcium uptake by Ehrlich ascites tumor cells showed that albumin and ATP decreased iron uptake, whereas calcium incorporation is diminished by albumin but augmented by ATP. This difference might be explained by albumin binding of ferric lactate that is inhibited from reaching cell structures, whereas ATP, known to be an inhibitor of iron polimerization, facilitates it. 相似文献