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  • 1
    Electronic Resource
    Electronic Resource
    Regeneration of fertile plants from isolated zygotes of rice (Oryza sativa) (1999)
    Springer
    Plant cell reports 19 (1999), S. 128-132 
    Details
    ISSN: 1432-203X
    Keywords: Key words Zygote ; Egg cell ; Plant regeneration ; Individual culture ; Rice ; Oryza sativa
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A simple mechanical method has been developed which allows the routine isolation of unfertilized and fertilized egg cells from ovules of Japonica and Indica rice varieties. In the experiments described, the majority of the egg cells and zygotes survived the isolation procedure when the donor plants were in a vigorous state. About 40% of the surviving zygotes underwent sustained development when cultured in Millicell inserts with a non-morphogenic rice feeder-cell culture. Nearly all zygote-derived callus cultures regenerated multiple shoots, which could be subsequently rooted with high efficiency. Zygote-derived plantlets matured to fertile plants when transplanted to soil. So far, about 80 independent plants each from the Japonica variety 'Taipei309' and the Indica variety 'IR58' have been regenerated. The potential of this single-cell regeneration system for marker gene-free transformation is discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002990050722
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  • 2
    Electronic Resource
    Electronic Resource
    Mapping QTLs for root traits in a recombinant inbred population from two indica ecotypes in rice (2000)
    Springer
    Theoretical and applied genetics 101 (2000), S. 756-766 
    Details
    ISSN: 1432-2242
    Keywords: Key words DNA markers ; Drought resistance ; QTLs ; Rice ; Root penetration
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract  Evaluation of root traits in rainfed lowland rice is very difficult. Molecular genetic markers could be used as an alternative strategy to phenotypic selection for the improvement of rice root traits. This research was undertaken to map QTLs associated with five root traits using RFLP and AFLP markers. Recombinant inbred lines (RILs) were developed from two indica parents, IR58821–23-B-1–2-1 and IR52561-UBN-1–1-2, that were adapted to rainfed lowland production systems. Using wax-petrolatum layers to simulate a hardpan in the soil, 166 RILs were evaluated for total root number (TRN), penetrated root number (PRN), root penetration index (RPI, the ratio of PRN to TRN), penetrated root thickness (PRT) and penetrated root length (PRL) under greenhouse conditions during the summer and the fall of 1997. A genetic linkage map of 2022 cM length was constructed comprising 303 AFLP and 96 RFLP markers with an average marker space of 5.0 cM. QTL analysis via interval mapping detected 28 QTLs for these five root traits, which were located on chromosomes 1, 2, 3, 4, 6, 7, 10 and 11. Individual QTLs accounted for between 6 and 27% of the phenotypic variation. Most of the favorable alleles were derived from the parent IR58821–23-B-1–2-1, which was phenotypically superior in root traits related to drought resistance. Three out of six QTLs for RPI were detected in both summer and fall experiments and they also were associated with PRN in both experiments. Out of eight QTLs for RPT, five were common in both seasons. Two genomic regions on chromosome 2 were associated with three root traits (PRN, PRT and RPI), whereas three genomic regions on chromosomes 2 and 3 were associated with two root traits (PRT and RPI). Two QTLs affecting RPI and two QTLs affecting PRT were also found in similar genomic regions in other rice populations. The consistent QTLs across genetic backgrounds and the common QTLs detected in both experiments should be good candidates for marker-assisted selection toward the incorporation of root traits in a drought resistance breeding program, especially for rainfed lowland rice.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s001220051541
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  • 3
    Electronic Resource
    Electronic Resource
    Expression of the plasma membrane H+-ATPase gene in response to salt stress in a rice salt-tolerant mutant and its original variety (1999)
    Springer
    Theoretical and applied genetics 99 (1999), S. 1006-1011 
    Details
    ISSN: 1432-2242
    Keywords: Key words Plasma membrane H+-ATPase gene ; Salt stress ; Salt-tolerant mutant ; Rice
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract  Plasma membrane (PM) H+-ATPase plays an important role in the establishment and maintenance of ion homeostasis. To investigate its expression in the rice salt-tolerant mutant M-20 and the original variety 77–170 during salt stress, a cDNA fragment corresponding to the PM H+-ATPase gene was obtained by PCR from rice japonica variety 77–170 and designated as OSA3. Sequence analysis of OSA3 revealed its high homology with two other published PM H+-ATPase genes, OSA1 and OSA2, in rice. Southern-blot analysis detected a RFLP between M-20 and 77–170, and one copy of the OSA3 gene was mapped to a position on rice chromosome 12 where a salt tolerance QTL was closely located. The expression of the PM H+-ATPase gene, as revealed by the OSA3 fragment, was compared between M-20 and 77–170. The results demonstrated that M-20 shoots accumulated less transcripts than 77–170 shoots at a later stage of salt treatment, and M-20 showed high expression at 300 mM NaCl while 77–170 reached its maximum at 200 mM NaCl. In roots, the difference in the level of the PM H+-ATPase gene expression between stressed and non-stressed plants was substantially greater in M-20 than that in 77–170. The relative abundance of PM H+-ATPase gene transcripts in M-20 roots may indicate the active role of this gene in the strict control of Na+ and Cl+ uptake into root symplast and apoplast, and further translocation into the shoot, hence leading to the reduced gene expression of M-20 shoots under salt-stress conditions.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s001220051408
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  • 4
    Electronic Resource
    Electronic Resource
    Acrosome reaction of stallion spermatozoa evaluated with monoclonal antibody and zona-free hamster eggs (1990)
    New York, NY [u.a.] : Wiley-Blackwell
    Molecular Reproduction and Development 27 (1990), S. 152-158 
    Details
    ISSN: 1040-452X
    Keywords: Stallion spermatozoa ; Acrosome reaction ; Monoclonal antibody ; Zona-free hamster eggs ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: The acrosome of the stallion spermatozoon was visualized by indirect immunofluorescence with monoclonal antibody (18.6) which recognized an integral acrosomal membrane component. Localization was confirmed by electron microscopy using peroxidase labelled antibody. In fresh semen samples (n = 19), 73.9 ± 9.1% of the spermatozoa from five fertile stallions displayed a uniform bright fluorescence over their acrosome region. In two semen samples from an infertile stallion only 28% and 35% of spermatozoa showed the same pattern of fluorescence. Spermatozoa from fertile stallions incubated for up to 12 hours in TALP medium maintained motility and exhibited a significant progressive loss of acrosomes as detected by immunofluorescence. Alternatively, a similar loss of acrosomes could be induced with calcium ionophore A23187 over a 90 minute incubation. Ultrastructural observations and incubation with zona-free hamster eggs indicated that only with ionophore treatment was immunofluorescent acrosome loss correlated with a physiological acrosome reaction, while prolonged sperm incubation led to degenerative membrane changes. It was concluded that, if carefully validated, immunofluorescent localization of the acrosome of stallion sperm with monoclonal antibody could be used to monitor the acrosome reaction. Furthermore, definitive acrosome visualization would be valuable in assessing semen quality.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/mrd.1080270210
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  • 5
    Electronic Resource
    Electronic Resource
    In vitro fertilization of horse follicular oocytes matured in vitro (1990)
    New York, NY [u.a.] : Wiley-Blackwell
    Molecular Reproduction and Development 26 (1990), S. 361-365 
    Details
    ISSN: 1040-452X
    Keywords: Stallion spermatozoa ; lonophore ; IVF ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: In vitro fertilizing ability of stallion spermatozoa was assessed using horse follicular oocytes matured in vitro. After collection, stallion spermatozoa were either: 1) washed and incubated in TALP medium with 3 mg/ml bovine serum albumin (BSA) and 10 μg/ml heparin for 4 h, 2) washed and incubated in TALP with 3 mg/ml BSA for 3 h and cultured for a further 1 h with 1 mM caffeine and 5 mM dbcAMP, 3) washed and incubated in TALP medium with 3 mg/ml BSA at pH 7.9-8.2 for 2-4 h, or 4) diluted and incubated in TALP medium with 10 mg/ml BSA and 7.14 μM calcium ionophore A 23187 for 5-10 min followed by washing. After a given pretreatment, suspensions were diluted into B2 medium to a concentration of 5 × 106 sperm/ml and co-incubated with oocytes for 12 h or 24-48 h. In the ionophoretreated group, 18 of 54 oocytes (33%) were fertilized by 12 h, and 11 of 45 (24%) cleaved by 24-48 h. Evidence of fertilization was not found in the oocytes incubated with spermatozoa from other treatment procedures.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/mrd.1080260411
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  • 6
    Electronic Resource
    Electronic Resource
    High-resolution electron microscopy of high-temperature superconductors (1988)
    New York, NY : Wiley-Blackwell
    Journal of Electron Microscopy Technique 8 (1988), S. 297-306 
    Details
    ISSN: 0741-0581
    Keywords: Defects ; Polymorphs ; Structure ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Natural Sciences in General
    Notes: We review recent results obtained at Northwestern using high-resolution electron microscopy to study high-temperature superconductors. While in general these materials form large, very perfect single crystal grains which display very few imperfections, there is also evidence of slip defects, amorphous regions, and order-disorder transformations. We also report that the gadolinium-based superconductors and in one case yttrium-based superconductors show evidence for some copper solid solubility in the form of copperrich planar defects. The structure of a metastable trigonal polytype is also reported, as are the effects of electron beam and water vapor damage to the materials.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jemt.1060080308
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