多价染色体

While under natural low temperature (10-20℃), a great deal of abnormalities, including micro nucleoli, scattered and lagged chromosomes and anaphase bridges were detected during PMC meiosis, even though the abnormalities were different between the two cultivars; the ratio of micro nucleoli was 22.88% of average, which was obviously higher than that of control (4.56% of average under normal temperature); and the ratios of univalent and multivalent in diplotene, which increased seriously, were 8.82% and 17.65% of Tainong 1, and 14.52% and 24.19% of Irwin under natural low temperatures.

低温（10~20℃）条件下，减数分裂过程中核仁的行为发生大量异常，微核仁的平均检出率高达22.88%，明显高于常温条件下的平均4.56%；双线期单价体和多价体的发生频率有明显增加，其中台农1号为8.82%和17.65%，Irwin为14.52%和24.19%；减数分裂中期Ⅰ、Ⅱ及后期Ⅰ、Ⅱ均观察到落后染色体，其中台农1号异常率为12.73%、5.63%、15.79%和4.76%，Irwin为11.11%、7.61%、9.52和6.38%。

In addition, some abnormal cytology behaviors, such as univalence, multivalence, chromosome bridges, lagging chromosomes, non-equivalent division, and micro-nucleus, etc. were also observed in the meiosis of pollen mother cell.

在杉木花粉母细胞减数分裂过程中观察到一些异常细胞学行为，即单价体和多价体、染色体桥、滞后染色体、不均等分离、微核等异常现象。

Its chromosome consists of 4.6×106 bases, which can be used as a vector of multivalent vaccine.

其染色体DNA含有4.6×10~6个碱基，可以作为建立多价疫苗的一种大的载体。

Results showed that the PMC meiosis of autotetraploid was similar to the diploid except some particularities. In metaphase Ⅰ, multivalent, quadrivalent, trivalent, bivalent and univalent were observed and some of the chromosomes were found not to rank on the metaphase plate and so did in metaphase Ⅱ cells. In anaphase Ⅰ and anaphase Ⅱ cells, there were lagging chromosomes, chromosome bridge and fragment. During anaphase Ⅱ and telophase Ⅱ, chromosome segregation was not synchronous or equal. At tetrad stage, dyad, triad, tetrad with micronucleus and polyad appeared.

结果表明，同源四倍体花粉母细胞减数分裂过程与二倍体相比，中期Ⅰ染色体构型复杂，有多价体、四价体、三价体、二价体和单价体；中期Ⅰ及中期Ⅱ有部分染色体没有排列在赤道板上；后期Ⅰ及后期Ⅱ出现落后染色体、染色体桥及断片；后期Ⅱ和末期Ⅱ有染色体不同步分离及不等分裂的现象；四分体时期还出现二分体、三分体、含微核的异常四分体及多分体。

The cytogenetics of interspecific hybrids among the four cultivated cotton species were studied in this paper and results are as follows: The diploid interspecific hybrid (G. arboreum×G. herbacium) F〓 had a four-chromosome-ring at the meiotic metakinesis. The synapses of tetraploid hybrid (G. hirsutum ×G. barbadense) F〓 was found to be regular, which mainly formed bivalents, sometimes some univalents, multivalents and chromosome bridge.

四个栽培棉种间杂交种F〓的细胞学观察结果表明，F〓减数分裂中期Ⅰ，形成一个环状四价体，直接证明了亚洲棉与草棉之间存在一对相互易位；F〓减数分裂中期Ⅰ联会基本正常，主要形成二价体，偶尔出现一些单价体和多价体，以及染色体桥。

The results showed that: at metaphase I, the homoeologous chromosome pairing among different F1 hybrids ranged from 2.0 to 11.4 bi-valents formed by homoeologous chromosomes per pollen mother cell, and very few multivalents, and even very few bivalents were formed by two chromosomes within one genome rather than homoeologous chromosomes in some PMCs; at anaphase I, all biva-lents were disjoined and most univalents were divided.

结果表明在中期I阶段，这些杂种一代的近缘染色体联会变化很大，每个花粉母细胞中二价体形成的数目从平均2个到11.4个不等，甚至在某些花粉母细胞中，还发现极少的多价体和非部分同源染色体所形成的单基因组内二价体；在后期I时，所有的二价体分离，同时多数单价体也分离，分离的二价体和分离的单价体都移向两极，从而形成两组染色体；因为这时完整花粉母细胞中分离的二价体在两组染色体中总是对应出现，从而根据半二价体上染色体重组的位置可以分析在二价体的四分体时期发生在非姊妹染色体之间的多种染色体交换类型，如单交换、三线双交换、四线双交换、四线三交换和四线多交换。

Under normal temperature (25-30℃), the process of pollen mother cell meiosis is normal; The most of chromosomes become bivalents which like "V","O","Y","X", sticks and dots, and mainly like dots,"V" and "O"; and a few of univalent (0.79% of Tainong 1 and 0 of Irwin) and multivalent (4.76% of Tainong 1 and 3.57% of Irwin) had been observed.

常温（25~30℃）条件下，花粉母细胞减数分裂过程较为正常，双线期染色体主要形成二价体，二价体构型以&V&型、&O&型、&Y&型、&X&型、点状和棒状等形式存在，并以点状、&V&型和&O&型较多见，出现少量的单价体和多价体，其中台农1号为0.79%和4.76%，Irwin为0和3.57%；同时仅在少量中期Ⅱ和后期Ⅱ花粉母细胞中观察到落后染色体。

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。