同源四倍性

In the self-bred progenies of autopolyploid,we found that a very few chimaeraexist in the cells of root tips,but most of them had no change in ploidy. We also found13 diploid plants in the experimental plot (ratio is 0.46%) and can be divided into 4categories.

在部分同源多倍体株系的自交结实后代中，随机取样进行根尖染色体检查，结果表明多倍株系体的自交结实后代倍性没有变化，但发现有个别细胞为不同倍性的嵌合体；田间观察到分离出来的极少数正常二倍体，占0.46％，按照形态特征可以分成四个不同的类型。

So, the abnormality of embryo sac was one of the factors that induce low seed setting percentage in autotetraploid rice.

从对13个品种的成熟胚囊育性调查的结果来看，同源四倍体水稻胚囊育性是影响其结实率的原因之一。

Study on the pollen fertility and the process of pollen formation and development in autotetraploid rice showed that the pollen fertility was high (78.33%), though many abnormities appeared in this process.

通过对5个品种的同源四倍体水稻花粉发育过程和13 个品种的花粉育性调查结果表明，同源四倍体花粉平均育性为78.33%，明显比二倍体（91.85%）低。

In conclusion, abnormal meiosis of PM-Cs is the cytogenetic causes for fertility reduction of tetraploid melon.

花粉母细胞减数分裂的异常是同源四倍体甜瓜育性低的细胞学原因。

This may be due to the characteristics of soybean genome,an ancient tetraploid.

这些基因位于10条不同染色体上，FT类基因具有成对排列于同一条染色体的短的区段的倾向，TFL1和CEN的4个不同拷贝均位于不同的染色体上。7对基因之间同源性高于90%，而且多位于不同染色体上，可能与大豆古四倍体的特性有关。4。

The phylogenetic analysis based on the sequences in this region indicated that the y-type HMW glutenin subunits of Agropyron elongatum species were different from other subunits, whereas the x-type subunits of them were most closely related to that from the B genome.

推测四倍体长穗偃麦草中的E1基因组可能起源于二倍体的E基因组。与来自小麦族的A、B、D和G基因组部分亚基基因的启动子序列比较表明，小麦族的这一区域在进化上是相当保守的，不同基因组来源的序列同源性都在90%以上。

However, analysis of DNA methylation level indicated that the total DNA methylation levels were not significantly different between diploid and autotetraploid. Autotriploid showed a trend of low DNA methylation level. It implied that the alterations of DNA methylation levels were not linear with the autopolyploidy level in watermelon.

有趣地是，二倍体与四倍体西瓜相比DNA甲基化水准却未发生大规模的调整，而三倍体西瓜显示出较为明显的低DNA甲基化水准趋势，表明西瓜同源多倍化过程中其基因组DNA甲基化水准变化与其倍性不成线性关系。

Thus, the meiotic chromosome cofigurations showed that the tetraploids and hexaploids in C.reticulata allopolyploids, and the appearance of a few tetravalents in some populations might indicatehomology of chromosomes in different genomes to some extent.

根据减数分裂的构型，我们认为，四倍体和六倍体分别为异源四倍体和异源六倍体，少数四价体的存在表明染色体有部分同源性。

Most primers amplified same bands in diploids, tetraploids and hexaploids. It suggest that D and AB genomes have high homology and D genomes be successfully transferred from diploid to hexaploid.

从供试的绝大多数引物均能在不同倍性小麦中扩增出相同的条带证明了D染色体组和AB染色体组间存在着很高的同源性以及利用二倍体和四倍体小麦杂交人工合成六倍体小麦的真实性。

According to the clear water experiment, aeration performance of the new equipment is good with high total oxygen transfer coefficient and oxygen utilization ratio.

曝气设备的动力效率在叶轮转速为120rpm～150rpm时取得最大值，此时氧利用率和充氧能力也具有较高值。

The environmental stability of that world - including its crushing pressures and icy darkness - means that some of its most famous inhabitants have survived for eons as evolutionary throwbacks, their bodies undergoing little change.

稳定的海底环境─包括能把人压扁的压力和冰冷的黑暗─意谓海底某些最知名的栖居生物已以演化返祖的样态活了万世，形体几无变化。