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101.
Summary Chromosome errors, inherited or arising de novo during gametogenesis and transmitted at fertilization to the conceptus, may be a major cause of embryonic mortality. The in vitro fertilization and embryo transfer (IVF/ET) procedure provides extra material — oo-cytes, zygotes, and embryos — to investigate the contribution of chromosomal abnormality to implantation failure. This paper reviews the results of cytogenetic studies on such material. Estimates from a total of 1120 oocytes from 11 studies give an overall proportion of chromosomal abnormality of 35%. Single and multiple nullisomies and disomies are found, involving nonrandom chromosome gain or loss. Hypohaploid complements are more frequent than hyperhaploid complements. The higher rate of chromosome loss of hypohaploid karyotypes was found to be largely artifactual. The estimated overall frequency of aneuploidy is 13%. In embryos the level of chromosomal abnormality is 23%–40%. Errors of fertilization are responsible for a substantial number of triploid embryos, many of which develop into mosaics. Factors extrinsic to the conceptus, such as infertility, advanced maternal age, and ovarian hyperstimulation, may increase the level of chromosomal abnormality. More refined methods for accurately recognizing and selecting chromosomally normal embryos for transfer are needed to improve the success rate of this reproductive technology. 相似文献
102.
Variants of the anti-Müllerian hormone gene in a compound heterozygote with the persistent Müllerian duct syndrome and his family 总被引:25,自引:0,他引:25
Danièle Carré-Eusèbe Sandrine Imbeaud Madeleine Harbison Maria I. New Nathalie Josso Jean-Yves Picard 《Human genetics》1992,89(4):389-394
Summary The human genome contains a large number of interspersed simple repeat sequences that are variable in length and can therefore serve as highly informative, polymorphic markers. Typing procedures include conventional multilocus and single locus probing, and polymerase chain reaction aided analysis. We have identified simple sequences in a cosmid clone stemming from the human Y chromosome and consisting of (gata)n repeats. We have compared these with two equivalent simple repeat loci from chromosome 12. After amplifying the tandemly repeated motifs, we detected between four and eight different alleles at each of the three loci. Codominant inheritance of the alleles was established in family studies and the informativity of the simple repeat loci was determined by typing unrelated individuals. The polymorphisms are suitable for application in linkage studies, practical forensic case work, deficiency cases in paternity determination, and for studying ethnological questions. The mutational mechanisms that bring about changes in simple repeats located both on the autosomes and on the sex chromosomes, are discussed.Professor Dr. Otto Prokop (Humboldt-Universität Berlin) on the occasion of his 70th birthday 相似文献
103.
Occurrence of a capsule in Aeromonas salmonicida 总被引:3,自引:0,他引:3
Antonieta Garrote Ramon Bonet Susana Merino Maria Dolors Simon-Pujol Francisco Congregado 《FEMS microbiology letters》1992,95(2-3):127-131
Aeromonas salmonicida grown in a medium with excess glucose as carbon source produces both capsular and exocellular polysaccharides. The capsular polysaccharide is composed of glucose, mannose, rhamnose, N-acetylmannosamine and mannuronic acid in the molar ratios of approximately 5:3:0.75:2:1. The extracellular polysaccharide is similarly constituted, but in the molar ratios of approximately 4.75:10.5:1.5:2:1. The capsular and exocellular polysaccharides did not cross-react with monoclonal antibodies against the A-layer or the O-antigen lipopolysaccharide. 相似文献
104.
Nutrient transfer between the root zones of soybean and maize plants connected by a common mycorrhizal mycelium 总被引:8,自引:0,他引:8
Gabor J. Bethlenfalvay Maria G. Reyes-Solis Susan B. Camel Ronald Ferrera-Cerrato 《Physiologia plantarum》1991,82(3):423-432
The objective of the study was to determine whether nutrient fluxes mediated by hyphae of vesicular-arbuscular mycorrhizal (VAM) fungi between the root zones of grass and legume plants differ with the legume's mode of N nutrition. The plants, nodulating or nonnodulating isolines of soybean [ Glycine max (L.) Merr.], were grown in association with a dwarf maize ( Zea mays L.) cultivar in containers which interposed a 6-cm-wide root-free soil bridge between legume and grass container compartments. The bridge was delimited by screens (44 μm) which permitted the passage of hyphae, but not of roots and minimized non VAM interactions between the plants. All plants were colonized by the VAM fungus Glomus mosseae (Nicol. & Gerd.) Gerd. and Trappe. The effects of N input to N-sufficient soybean plants through N2 -fixation or N-fertilization on associated maize-plant growth and nutrition were compared to those of an N-deficient (nonnodulating, unfertilized) soybean control. Maize, when associated with the N-fertilized soybean, increased 19% in biomass, 67% in N content and 77% in leaf N concentration relative to the maize plants of the N-deficient association. When maize was grown with nodulated soybean, maize N content increased by 22%, biomass did not change, but P content declined by 16%. Spore production by the VAM fungus was greatest in the soils of both plants of the N-fertilized treatment. The patterns of N and P distribution, as well as those of the other essential elements, indicated that association with the N-fertilized soybean plants was more advantageous to maize than was association with the N2 -fixing ones. 相似文献
105.
Maria L. Boccia Martin L. Reite Kristine Kaemingk Polly Held Mark L. Laudenslager 《Primates; journal of primatology》1991,32(2):255-263
The social environment affects both behavioral and physiological responses to separation from the mother. Less information
is available on the impact of the social environment on the response to separation in peer-reared infant monkeys. This study
reports the responses of peer-reared pigtail macaque infants to repeated separations, and the impact of social versus isolation
housing during the separation. The responses of two pairs of monkeys were studied during four three-day separations. One of
each pair was housed in isolation during the separation, and the other was with another pair of peers, with whom they had
been living for one month prior to the separation. The isolation-housed peer responded to the separation with behavioral agitation,
but no depression. The socially-housed peer's behavior did not differ from baseline during the separation. During successive
reunions, all the separated monkeys, regardless of housing condition, exhibited declining levels of behaviors related to maintaining
proximity to their attachment figure. Although the number of subjects is small, the results suggest that the presence of social
support, in the form of a familiar peer, can ameliorate the response to separation, and that with repeated separations the
responses of the monkeys changes significantly. 相似文献
106.
Maria Jesús García Rosario Brieva Francisca Rebolledo Vicente Gotor 《Biotechnology letters》1991,13(12):867-870
Summary 2,2,2-Trifluoroethyl -chloro--phenylacetate is succesfully hydrolysed in organic solvent in the presence of aniline andCandida cylindracea orPseudomonas cepacia lipase as catalysts. 相似文献
107.
Maria Ransjö 《Bioscience reports》1991,11(4):203-211
The protein kinase C-(PKC) activating phorbol esters 12-O-tetradecanoylphorbol-13-acetate (TPA; 100 nmol/l) and phorbol 12, 13-dibutyrate (PDBU; 100 nmol/l) enhanced basal cyclin AMP accumulation in cultured neonatal mouse calvaria. The cyclic AMP response to parathyroid hormone (PTH; 10 nmol/l) and the adenylate cyclase activators forskolin (1–3 mol/l) and choleratoxin (0.1 mg/ml) was potentiated in a more than additive manner by TPA and PDBU. In contrast, phorbol 13-monoacetate (phorb-13; 100 nmol/l), a related compound but inactive on PKC, had no effect on basal or stimulated cyclic AMP accumulation. In the presence of indomethacin (1mol/l), TPA and PDBU had no effect on cyclic AMP accumulation in calvarial bones per se, but were still able to cause a significant enhancement of the response to PTH, forskolin and choleratoxin. PTH-, forskolin- and choleratoxin-stimulated cyclic AMP accumulation in rat osteosarcoma cells UMR 106-01 was synergistically potentiated by TPA and PDBU, but not by phorb.-13. These data indicate that PKC enhances cyclic AMP formation and that the level of interaction may be at, or distal to, adenylate cyclase. 相似文献
108.
Josep Vilardell John Mundy Bodil Stilling Bernard Leroux Maria Pla Georges Freyssinet Montserrat Pagès 《Plant molecular biology》1991,17(5):985-993
The maizerab17 gene is expressed in different plant parts in response to ABA and osmotic stress (J. Vilardellet al., Plant Mol Biol 14 (1990) 423–432). Here we demonstrate that 5 upstream sequences of therab17 gene confer the appropriate patterns of expression on the chloramphenicol acetyl transferase (CAT) reporter gene in transgenic tobacco plants, as well as in protoplasts derived from cultured rice cells. Specifically, a CAT construct containing a large 5 upstream fragment ofrab17 (–1330/+29) results in high levels of CAT activity in embryos, leaves and roots of transgenic plants subjected to water stress or ABA treatment. Transient expression assays in rice protoplasts transfected with CAT genes fused torab17 promoter deletions indicate that a 300 bp DNA fragment (–351/–102) is sufficient to confer ABA responsiveness upon the reporter gene. Furthermore, a 100 bp sequence (–219/–102) is capable of conferring ABA responsiveness upon a minimal promoter derived from the 35S CaMV promoter. Gel retardation experiments indicate that maize nuclear proteins bind to this fragment. This region of 100 bp contains a sequence (ACGTGGC) which has been identified as an abscisic acid response element in studies of other ABA-responsive plant genes. 相似文献
109.
Ivano Bertini Bertini Luchinat Mario Piccioli Margarita Vicens Oliver Maria Silvia Viezzoli 《European biophysics journal : EBJ》1991,20(5):269-279
Human copper-cobalt superoxide dismutase in the reduced form has been investigated through 1H NMR techniques. The aim is to monitor the structural properties of this derivative and to compare them with those of reduced and oxidized native superoxide dismutases. The observed signals of the cobalt ligands have been assigned as well as the signals of the histidines bound to copper(I). The latter signals experience little pseudocontact shifts which allow a rough orientation of the magnetic susceptibility tensor in the molecular frame. The connectivities indicate that, although the histidine bridge is broken in the reduced form, the interproton distances between ligands of both ions are essentially the same.Abbreviations WEFT
water eliminated Fourier transform
- NOE
nuclear Overhauser effect
- NOESY
NOE spectroscopy
- COSY
correlation spectroscopy
- TOCSY
total correlation spectroscopy
- SOD
superoxide dismutase
- E2Co(II)SOD
SOD with empty copper site (E=empty) and with cobalt(II) in the Zinc(II) site
Offprint requests to: I. Bertini 相似文献
110.
Rita Maria Ulloa Hector Norberto Torres Claudia M. Ochatt Maria Teresa Téllez-Iñón 《Molecular and cellular biochemistry》1991,102(2):155-163
DEAE-cellulose column chromatography of Neurospora crassa soluble mycelial extracts leads to the resolution of three major protein kinase activity peaks designated PKI, PKII, and PKIII.PKII activity is stimulated by Ca2+ and Neurospora or brain calmodulin. Maximal stimulation was observed at 2 µM-free Ca2+ and 1 µg/ml of the modulator. The stimulatory effect of the Ca2+-calmodulin complex was blocked by EGTA and by some calmodulin antagonists such as phenothiazine drugs or compound 48/80.PKII phosphorylates different proteins, among which histone II-A at a low concentration and CDPKS, the synthetic peptide specific for Ca2+-calmodulin dependent protein kinases, are the best substrates. Some phosphorylation can be detected in the absence of any exogenous acceptor. PKII activity assayed in the presence of histone II-A or in the absence of exogenous phosphate acceptor (autophosphorylation) co-elute in a DEAE-cellulose column at 0.28 M NaCl. As result of the autophosphorylation reaction of the purified enzyme a main phosphorylated component of 70 kDa was resolved by SDS-polyacrylamide gel electrophoresis. It is possible that this component is an active part of this enzyme. 相似文献