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31.
T. Komari 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》1990,80(2):167-171
Summary A leaf-disk transformation experiment was performed with tobacco (Nicotiana tabacum L.) using a binary vector and a strain of Agrobacterium tumefaciens that carried a wild-type Ti-plasmid, pTiBo542. Although the majority of kanamycin-resistant, transgenic plants was morphologically normal, one of the plants was double-flowered and had a slightly wavy stem and leaves whose edges were bent slightly upwards. The abnormal morphology was controlled by a single, dominant Mendelian gene. Young plants that carried this gene were distinguishable from normal plants at the stage of cotyledons. The homozygotes, with respect to this gene, were more seriously deformed than the heterozygotes. DNA segments derived from the binary vector and from the TL-and TR-DNA of pTiBo542 were detected in the double-flowered plant, but the T-DNA genes involved in biosynthesis of phytohormones were absent from the plant. The abnormal morphology, the resistance to kanamycin, and the segments of foreign DNA were genetically linked, and the linkage was very tight, at least between the abnormal morphology and the resistance to kanamycin; the meiotic recombination frequency was less than 0.02%, if recombination occurred at all. 相似文献
32.
Penetration of intact bovine ova with ram sperm in vitro 总被引:1,自引:0,他引:1
In culture, mature bovine ovarian oocytes were fertilized in vitro with freshly ejaculated ram spermatozoa treated with heparin. The zona pellucida does not prevent penetration of ram spermatozoa. The penetration rate varied between 10 and 84%, and in most instances, after 24 hr of culture, two normal-looking pronuclei and sperm tail were present in the cytoplasm. These results suggest that the zona pellucida of bovine oocytes does not represent a barrier for the penetration of ram spermatozoa. 相似文献
33.
Allison A. Snow Timothy P. Spira 《Evolution; international journal of organic evolution》1996,50(5):1866-1870
The stigmas of animal-pollinated flowers often capture more pollen than is needed to fertilize all available ovules, and mixed-donor pollen loads are probably common. When this is the case, variation in average pollen-tube growth rates can potentially affect the number of seeds sired by a given plant. Despite considerable interest in effects of postpollination processes on male fitness, little is known about the extent of variation in pollen performance among plants from natural populations. To examine this question in Hibiscus moscheutos (rose mallow), we conducted mixed-donor hand-pollination experiments with 39 pollen donors bearing distinctive isozyme markers. Pairs of competing donors were compared on sets of 11 to 15 recipient plants per pair. These donors often differed in the proportions of seeds they sired, with the maximum deviation from an expected ratio of 50:50 being 68:32. Furthermore, three intensively studied plants exhibited consistent trends in relative pollen performance when each was tested against (1) the same three competitors, and (2) groups of 14 competitors chosen at random from the study population. In a separate experiment, we investigated the effects of salinity stress and high soil nutrients on pollen performance. These environmental factors had anticipated effects on leaf production, flower production, and petal length, but style length and (most importantly) the number of seeds sired relative to a standard pollen donor were not affected. In summary, this study provides the strongest evidence to date that pollen-tube competitive ability varies among coexisting plants and may be an important component of male fitness in plants. 相似文献
34.
Frederick J. Griffin Carol A. Vines Murali C. Pillai Ryuzo Yanagimachi Gary N. Cherr 《Development, growth & differentiation》1996,38(2):193-202
Polyclonal antibodies were generated to the 105 kDa herring sperm motility initiation factor (SMIF) and used to explore the role of SMIF in sperm-egg interaction. Using sodium dodecyl sulfate polyacrylamide gel electrophoresis and immunoblotting with SMIF antibodies, it was demonstrated that SMIF is present as a minor (4–7% of total chorion protein) component of the chorion. The major polypeptides in the chorion migrated at 117 kDa and in a grouping between 48–54 kDa, with other minor bands above and below. The only detectable glycosylated component was the 105 kDa band, which was resolved at two isoelectric points (8.22 and 8.31) after isoelectric focusing gel electrophoresis. Using antibodies to SMIF, fertilization was blocked, sperm motility was inhibited in vitro in the presence of solubilized SMIF and SMIF binding sites on sperm were localized. Lastly, SMIF was localized to the region of the herring egg that encircles the micropyle. 相似文献
35.
黑节草从传粉到受精约需130d,精子在花粉管中形成,胚囊发育属蓼型胚囊,因反足细胞较早退化,故受精前胚囊多只由卵器和中央细胞组成。精卵核融合时,精核染色质进入卵核后凝集成颗粒状,并在原位与卵核的染色质融合,雌、雄性核仁一直维持至合子的第一次分裂期前。双受精作用正常,属于有丝分裂前配子融合类型,初生胚乳核发生2-3次分裂后逐渐退化消失,胚的发育局限于球形胚阶段。 相似文献
36.
Communication between the oocyte and its somatic cells has been shown to be important in oocyte development. Here we examined how the oocyte may be involved in bovine cumulus cell expansion. Intact bovine cumulus oocyte complexes (COC) were obtained by puncturing antral follicles. From the intact COC, oocytectomised complexes (OOX) were produced by micro surgical removal of the oocyte. Clumps of cumulus cells (CC) were obtained by micro-dissection. Intact or OOX complexes or CC were matured in the presence of fetal calf serum and hFSH (6 mlU/ml) for 24 hr and the degree of expansion measured. The presence of the oocyte is not essential to allow bovine cumulus expansion to occur as expansion occurred in all groups. Murine OOX complexes from eCG primed 35–40-day-old C57BL6/CBA F1 hybrids (known to require the presence of an oocyte secreted factor for cumulus expansion) were cultured with or without denuded bovine oocytes (1 oocyte/μl). Murine OOX complexes expanded only in the presence of denuded bovine oocytes. Thus some factor produced by bovine oocytes enabled expansion of murine OOX complexes. To determine whether the factor is secreted by bovine oocytes, murine OOX were cultured with or without media conditioned by bovine oocytes (1 oocyte/μl for 4 hr). Significant expansion of murine OOX occurred in media conditioned by bovine oocytes. This shows that the cumulus expansion enabling effect of bovine oocytes is released into the surrounding media. Media conditioned by bovine oocytes and then frozen for up to 1 month showed that the activity by the factor can withstand freezing. © 1995 wiley-Liss, Inc. 相似文献
37.
Abstract. To test if low soil fertility and competition limit the performance of Mediterranean shrubs, and if the effects of competition on plant performance were modified by soil fertility, we subjected shrubs of Erica multiflora to a factorial field experiment of fertilization and removal of neighbours around target plants. After 18 months of treatment, fertilization had stimulated the growth of pre-existent sprouts and biomass allocation to stems into new sprouts, but decreased the frequency of sprout flowering. Removal of neighbours increased the number and biomass of new sprouts, the probability of sprout flowering and the biomass of flowers. Fertilization slightly enhanced sprout recruitment and the probability of sprout flowering when neighbours were removed, but did not modify the other parameters of plant performance. According to our results, both low soil fertility and competition limited plant performance. Competition was slightly more intense in fertilized plants, but only in determining sprout and flowering bud stimulation. 相似文献
38.
Nutrient additions to wetlands in the Interlake region of Manitoba,Canada: effects of a single pulse addition in spring 总被引:3,自引:3,他引:0
Gabor T. S. Murkin H. R. Stainton M. P. Boughen J. A. Titman R. D. 《Hydrobiologia》1994,279(1):497-510
This study examined the responses of algae and invertebrates to a single application of N and P in a series of experimental wetland enclosures in the Interlake region of Manitoba during 1989 and 1990. N and P levels in the water, sediment and vegetation were also monitored. The 3 fertilization treatments were: dissolved inorganic (6200 µg 1–1 N, 420 µg 1–1 P), dissolved inorganic (3200 µg 1–1 N, 210 µg 1–1 P) and organic (ground alfalfa meal: 6200 µg 1–1 420 µg 1–1 P).Dissolved nutrients in the inorganic treatments were quickly depleted from the water column, but dissolved N increased in the water column of the alfalfa treatment as the alfalfa decomposed. No changes in N or P concentrations in the sediments or vegetation were detected. Phytoplankton biomass increased in all fertilized enclosures while epiphytic periphyton exhibited only minor responses. Epipelon biomass increased in the alfalfa treatment and metaphyton standing crops were highest in the high inorganic treatments.In the alfalfa treatment, high microbial respiration rapidly reduced dissolved oxygen concentrations which negatively affected invertebrates. This trend reversed as oxygen levels increased later in the experiment. Dominant nektonic and benthic invertebrates increased in the high inorganic and alfalfa treatments. Orthocladiinae emergence increased in the high inorganic and alfalfa treatments, while Chironominae and Tanypodinae increased in the alfalfa treatment. Second year responses by algae and invertebrate communities to the fertilization treatments were minimal. Annual single pulse fertilization has the potential to increase the productivity of Interlake wetlands when nutrients are applied in the spring, however it should be noted that at the levels used in this study the effects did not extend to the second year. 相似文献
39.
40.
Increased biomass production in terrestrial ecosystems with elevated atmospheric CO2 may be constrained by nutrient limitations as a result of increased requirement or reduced availability caused by reduced
turnover rates of nutrients. To determine the short-term impact of nitrogen (N) fertilization on plant biomass production
under elevated CO2, we compared the response of N-fertilized tallgrass prairie at ambient and twice-ambient CO2 levels over a 2-year period. Native tallgrass prairie plots (4.5 m diameter) were exposed continuously (24 h) to ambient
and twice-ambient CO2 from 1 April to 26 October. We compared our results to an unfertilized companion experiment on the same research site. Above-
and belowground biomass production and leaf area of fertilized plots were greater with elevated than ambient CO2 in both years. The increase in biomass at high CO2 occurred mainly aboveground in 1991, a dry year, and belowground in 1990, a wet year. Nitrogen concentration was lower in
plants exposed to elevated CO2, but total standing crop N was greater at high CO2. Increased root biomass under elevated CO2 apparently increased N uptake. The biomass production response to elevated CO2 was much greater on N-fertilized than unfertilized prairie, particularly in the dry year. We conclude that biomass production
response to elevated CO2 was suppressed by N limitation in years with below-normal precipitation. Reduced N concentration in above- and belowground
biomass could slow microbial degradation of soil organic matter and surface litter, thereby exacerbating N limitation in the
long term. 相似文献