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1.
A chromosomal method to distinguish between X- and Y-bearing spermatozoa of the bull in zona-free hamster ova 总被引:1,自引:0,他引:1
The interspecific in-vitro fertilization system using zona-free hamster ova was adopted to distinguish chromosomally between X- and Y-bearing bull spermatozoa. Frozen semen samples were thawed and washed with modified BWW medium including 0.3% BSA (pH 7.2) to remove cryoprotective medium. Motile spermatozoa were recovered from the semen by the 'swim-up' method. These spermatozoa were treated with ionophore A23187 to facilitate capacitation. Adequate capacitation of spermatozoa was found by their movement patterns and the insemination was performed at the optimum time. The fertilized ova were cultured in Medium TC199 with 10% FBS including podophyllotoxin and vinblastine until they reached first cleavage metaphase. Chromosome slides were prepared by our gradual fixation-air drying method. The success rate of the method was 56% of the number corresponding to the zona-free ova used. Altogether 1116 spermatozoa from 4 different bulls were successfully analysed and the ratio of X- and Y-bearing spermatozoa was 542:574 (P greater than 0.3). 相似文献
2.
The relationship between nitrification potential and nitrogen accumulation was studied in an early successional sere on Mt.
Fuji. Soil organic nitrogen accumulated with the invasion ofPolygonum cuspidatum and successively withMiscanthus oligostachyus and other species. Laboratory incubation experiments showed a higher nitrification potential at theM. oligostachyus state. The numbers of nitrifying bacteria increased with the progress of succession. No significant difference in nitrate
reductase activity was found between pioneer and succeeding species. The soil solution at theM. oligostachyus stage contained a lower level of nitrate than rainwater, while that of the bare ground and theP. cuspidatum stage contained a higher nitrate level than rainwater. It was concluded that the high nitrate levels in the soil solution
of the bare ground and theP. cuspidatum stage were due to lower nitrate-absorbing activity, leading to loss of nitrogen with precipitation, while the lower nitrate
levels at theM. oligostachyus stage when higher nitrification activity occurred were due to higher nitrate-absorbing activity, preventing net loss of nitrogen
from the ecosystem. 相似文献
3.
Masaki Tateno 《Ecological Research》1988,3(3):267-277
Air-dried fresh and dead specimens ofPolygonum cuspidatum were incubated for 250 days in the laboratory, and the growth and turnover of microbial biomass-C in the organic matter were
studied. The biomass-C in the fresh leaf and fresh stem attained maximum levels on day 14 and day 7, respectively, and then
settled down to stable levels. In the dead leaf and dead stem, increase in biomass-C ceased by day 4 and the biomass-C levels
did not change thereafter. The turnover time of the biomass-C was estimated from the amount of biomass-C and the release rate
of CO2-C. The turnover was rapid in the early period of incubation. Then the turnover time became longer and after incubation for
70 days the values approached those in natural soils (longer than 16 days). During the incubation period, nitrogen was not
mineralized in any organic matter. In the dead leaf and dead stem, asymbiotic nitrogen fixation activity increased after incubation
for about 40 days and disappeared by the end of the incubation period, whereas nitrogen fixation was hardly detected in the
fresh leaf and fresh stem. 相似文献
4.
Comparison of lodging safety factor of untreated and succinic Acid 2,2-dimethylhydrazide-treated shoots of mulberry tree 总被引:1,自引:0,他引:1 下载免费PDF全文
This study examined the lodging resistance of mulberry tree (Morus bombycis Koidz. cv Kenmochi) shoots treated or not treated with succinic acid 2,2-dimethylhydrazide (SADH). The lodging safety factor, an indicator of lodging resistance, was defined as the ratio of critical lodging load to the leaf fresh weight observed, provided that the distribution of the critical lodging load along the stem was similar to that of the leaf fresh weight observed. The critical lodging load was experimentally estimated by loading weights onto the stems. In the untreated trees, the lodging safety factor was maintained at about 3.2. In the SADH-treated trees, the stem elongation was inhibited to about 80% of that in the untreated trees, and the percentage of shoot dry matter partitioned into the leaves was always larger than that of the untreated trees. This dwarfing of the stem caused by SADH increased the critical lodging load supported by the unit stem dry weight, while this large investment of materials in leaves increased the leaf fresh weight supported by the unit stem dry weight. Since the increments canceled each other, the lodging safety factor of the SADH-treated shoots was similar to that of the untreated ones. These results suggest that the shoot formation of the mulberry tree is controlled to maintain the lodging safety factor at a constant level. 相似文献
5.
Effects of in vivo exposure with fenvalerate, esfenvalerate andDDT on hepatic gap junctional intercellular communication (GJIC) in Sprague-Dawley (SD) rats were examined by in vivolin vitro dye-transfer assay and by immunohistochemical staining of connexin 32 (C×32, major liver gap junction protein). Fenvalerate (75 mg/kg/day), esfenvalerate (25 mg/kg/day), DDT (50 mg/kg/day) and corn oil (vehicle control, 5mllkglday) were administered orally once a day. Animals were killed at weeks 1, 2, 4 and 6 after starting the experiment. In the fenvalerate- and esfenvalerate-groups, no compound-related changes in GJIC and C×32 expression were observed. On the contrary, in the DDT-group, average sizes of the dye spread after injection of Lucifer Yellow decreased at weeks 1, 2 and 4, and the area per GJ spot shown by C×32-immunohistochemical staining decreased at weeks 4 and 6. It is concluded that neither fenvalerate nor esfenvalerate inhibits hepatic GJIC with in vivo exposure. 相似文献
6.
In the presence of migration FST in a finite number of incompletely isolated populations first increases, but after reaching a certain maximum value, it starts to decline and eventually becomes 0. The mean and variance of FST in this process are studied by using the recurrence formulas for the moments of gene frequencies in the island model of finite size as well as by using Monte Carlo simulation. The mean and variance in the early generations can be predicted by the approximate formulas developed. On the other hand, if we exclude the cases of an allele being fixed in all subpopulations, the mean of FST eventually reaches a steady-state value. This value is given by 1 − 2NT(1 − λ) approximately, where NT is the total population size and λ is the rate of decay of heterozygosity at steady state. It is shown that the mean and variance of FST depend on the initial gene frequency and when this is close to 0 or 1, Lewontin and Krakauer's test of the neutrality of polymorphic genes is not valid. 相似文献
7.
Makoto Kimura Masaki Funakoshi Shinpei Sudo Takehiro Masuzawa Toshie Nakamura Kozue Matsuda 《Journal of plant research》1982,95(4):359-373
Annual net production was estimated in the secondary coppice forest near Tokyo, which was dominated by a deciduous oak,Quercus serrata Thunb. Lateral growth of stems and old branches was directly estimated by examining the annual rings for 35 shoots in a clear-cut
quadrat of 10m×10m. Phytomasses of current organs were also weighed in the quadrat. Preharvest losses of current organs were
determined by twelve 0.5 m2 litter traps for fine litter and twelve 6 m2 quadrats for woody litter. Branch production was also assessed indirectly by use of the stem-branch allometry and death of
branches. The results of the indirect method were in sufficient agreement with the result of the direct one. Grazing loss
of leaves from the canopy was estimated directly from the loss in leaf area and indirectly from the animal faeces caught by
the litter traps.
Net production of the canopy trees was 149 kg a−1 year−1, in which leaf production was 36.9 kg. Animals grazed about 14% of the leaf area by the end of the growing season. True consumption
of leaves by animals was 7.6% of leaf production or 10% of leaf mass. Production of undergrowth, mainly a dwarf bamboo,Pleioblastus chino Makino, was 28 kg a−1 year−1, being 15% of the total stand production.
Productivity of this forest was significantly higher than that of cool-temperate deciduous broadleaf forests. 相似文献
8.
9.
To test the hypothesis that xylariaceous endophytes were ubiquitous on live and dead leaves of various tree species in the field, xylariaceous fungi were isolated from live leaves and bleached and nonbleached portions of dead leaves of a total of 94 tree species in a cool temperate forest in Japan. The biodiversity of xylariaceous endophytes was evaluated as the richness of operational taxonomic units (OTUs) determined by phylogenetic analysis of the nucleotide sequence of the D1/D2 region of the LSU rDNA of fungal isolates. A total of 326 isolates of xylariaceous fungi were isolated from live and dead leaves and classified into 15 OTUs. The three major OTUs, Xylaria sp.1, Nemania sp., and Biscogniauxia sp., accounted for 94% (308 isolates) of the total number of isolates, and were isolated from various live and dead leaves. Xylaria sp.1 was frequently encountered on bleached portions (which were produced due to the selective decomposition of lignin) of dead leaves of broad-leaved deciduous tree species. The results suggest that xylariaceous endophytes did not show host specificity and had a saprobic phase on dead leaves in their life cycles and that Xylaria sp.1 was capable of decomposing lignin in the field conditions. 相似文献
10.
Krishna Nath Bong-Kwan Phee Suyeong Jeong Sun Yi Lee Yoshio Tateno Suleyman I. Allakhverdiev Choon-Hwan Lee Hong Gil Nam 《Photosynthesis research》2013,117(1-3):547-556
Photosynthetic complexes in the thylakoid membrane of plant leaves primarily function as energy-harvesting machinery during the growth period. However, leaves undergo developmental and functional transitions along aging and, at the senescence stage, these complexes become major sources for nutrients to be remobilized to other organs such as developing seeds. Here, we investigated age-dependent changes in the functions and compositions of photosynthetic complexes during natural leaf senescence in Arabidopsis thaliana. We found that Chl a/b ratios decreased during the natural leaf senescence along with decrease of the total chlorophyll content. The photosynthetic parameters measured by the chlorophyll fluorescence, photochemical efficiency (F v/F m) of photosystem II, non-photochemical quenching, and the electron transfer rate, showed a differential decline in the senescing part of the leaves. The CO2 assimilation rate and the activity of PSI activity measured from whole senescing leaves remained relatively intact until 28 days of leaf age but declined sharply thereafter. Examination of the behaviors of the individual components in the photosynthetic complex showed that the components on the whole are decreased, but again showed differential decline during leaf senescence. Notably, D1, a PSII reaction center protein, was almost not present but PsaA/B, a PSI reaction center protein is still remained at the senescence stage. Taken together, our results indicate that the compositions and structures of the photosynthetic complexes are differentially utilized at different stages of leaf, but the most dramatic change was observed at the senescence stage, possibly to comply with the physiological states of the senescence process. 相似文献