变异发生

The internal cause includes polarity variation , inbred variation , instability of hybridization and gene mutation . The external cause includes unfitting culture conditions , strain ag ing , unsuitable preservation and infection virus of asexuality propagation .

内因主要包括极性发生变异，自交产生的变异，杂交种性不稳定和基因突变；外因主要包括培养条件不适宜，菌种老化，菌种保藏不当和菌株无性繁殖体感染病毒。

Based on the understanding of physiological pathway for broodiness, three genes related to broodiness including PRL, PRL receptor, and pituitary-specific transcription factor (POU1F1)-encoding genes were selected as candidates to screen the genomic variation by means of PCR-SSCP protocol and analyze the association with chicken broodiness and other target traits.

禽类血浆PRL水平上升与就巢行为的起始和维持具有密切的相关性，本研究采用候选基因的策略，通过分析就巢行为发生的生理机制，选择与就巢性状密切关联的PRL、PRL受体和PRL转录调控因子——垂体特异转录因子(pituitary-specific transcription factor，POUlF1)基因，采用PCR-SSCP分析检测基因变异，并分析基因变异与就巢性和其它目标性状的相关性。

After being exposed to cosmic radiation and zero gravity, some seeds may mutate and produce higher yields and improved quality when planted back on earth, scientists said.

科学家介绍，在宇宙辐射和失重环境下，有些种子可能会发生变异，这些变异种种植到地球上后，能培育出高产优质的新品种。

The effects of different host plant on the stability of plasmid in HA 12-1-12 and HA 7-2-2 were also assessed.

进一步考察了其中两个菌株HA 12-1-12和HA 7-2-2的质粒在四种宿主体内的稳定性，结果表明HA 12-1-12在不同宿主体内高度稳定，HA 7-2-2却发生了不同程度的变异，得到10个变异株。

The results suggested that somaclonal variation in apple was lower than natural variation.

结果表明，苹果离体叶片直接体细胞胚胎发生途径再生植株的体细胞无性系变异率接近自然变异率

Those whose husbands had one or two copies of the gene variation scored significantly lower on tests asking about their marriage quality than those without it.

发表在《美国科学院学报》上的一篇对已婚妇女的调查结果也支持以上看法：那些具有1或2处基因变异的丈夫，他们的婚姻质量测试评分要明显低于没有发生基因变异的丈夫。

ABSTRACT It is because that the excellent acceptors for maize transgenic engineering are insufficient in our country, especially in the southwest mountain areas of china and hereditary variation regularity for the two characters such as efficiency of embryonic callus induction and number of regenerating plant (these two characters were abbreviated to the nduction efficiency and number of regenerating in the following of the paper, respectively), which hint the maize culturing capacity, is not very clear. Therefore, aiming at picking out superior acceptors, we had made systematic researches on the two characters with combing traditional quantitative-character genetic analyzing methods such as single-factor genetic mating design, diallel crossing genetic design, genetic effect analyzing method and the modern molecular locating method such as QTLs'. The main results are followed.(1) 50 superior inbred lines and about 30 crosses in our country, especially in the southwest of China were used for identifying and selecting the superior genotypes in the above two investigated characters under the same culturing condition in 2000 and 2001. There was very significant difference among the genotypes in the both characters. But the two characters were not certainly related. Some genotypes such as 18-599 and 18-599 were very good in them. For some ones such as zong 31, induction was higher than 18-599 and 18-599 in the efficiency, but it was only 1/3 to the later in regenerating number. In some genotypes such as S37, R08, R15, P138, A318, induction efficiency was just about 3% and scarcely any regenerating plants were got. On the whole, hybrids acted better than inbreeds in the both characters.(2) Two kind of inbreeds were selected as parents of the Griffing's method 1. 18-599 and 18-599 and the inbred line zong 31 are one kind because they are not only superior in the characters of maize cross breeding, such as CA, resistance to disease and the important agricultural characters, but also excellent in transformation characters as the induction and regeneration.

针对我国、特别是西南山地所需玉米转基因工程育种优良受体极为匮乏和反应玉米幼胚培养能力的2个主要性状，即玉米幼胚胚性愈伤组织诱导率和胚性愈伤组织绿苗发生数的遗传变异规律十分不清楚的实际情况，本研究从筛选玉米转基因工程所需要的优良受体入手，采用单因素遗传交配设计、双列杂交遗传交配设计、世代基因效应等传统数量性状分析方法，以及现代分子标记定位主效QTL分析方法，对玉米幼胚胚性愈伤组织诱导率和胚性愈伤组织绿苗发生数等2个性状进行了较为系统的分析研究，取得以下主要研究结果：(1)于2000年和2001年通过对我国、特别是西南地区近50份优良自交系和近30个杂交组合，在相同培养条件下，对幼胚培养胚性愈伤组织诱导率和胚性愈伤组织绿苗发生数等2个幼胚培养能力性状进行了筛选与鉴定，发现玉米不同基因型具有完全不同的幼胚培养胚性愈伤组织诱导率和胚性愈伤组织绿苗发生数，但幼胚培养胚性愈伤组织诱导率与胚性愈伤组织绿苗发生数并不具有必然的相关关系，有的基因型，如自交系18-599和18-599在胚性愈伤组织诱导率和愈伤组织绿苗发生数等2个性状都表现相当优异；有的基因型，如自交系综31，仅幼胚培养胚性愈伤组织诱导率性状表现高于19-599和18-599，但在胚性愈伤组织绿苗发生数这一性状则与它们有相当大的差距，仅为19-599和18-599的1/3左右；有的基因型，如S37、R08、R15、P138、A318等玉米自交系不仅幼胚培养胚性愈伤组织诱导率很低，平均仅在3％左右，而且胚性愈伤组织绿苗发生数表现也很差，基本上没有分化成苗。

Seedlings of the 538 precocious cross seedlings were observed on floral organ variations. The variation type includes Hermaphrodite flower, spike inflorescences, branch spike inflorescences, male and female flowers in one spike inflorescence, rosette male inflorescences.

在538株早实杂种苗中，共有12个单株在2a生时发生了花器变异，变异类型包括两性花类型、穗状花类型、穗状花具分枝类型、穗状花雌雄同序类型、柱头变异类型和雌花序莲座状类型。

From the probabilistic equation of debris-flow occurrence, the curves of probability-slope-water level were obtained. One can see the influences of water level and sediment-layer slope on the probability of occurrence from the curves. The influence of coefficients of variation on occurrence probability are also shown in this paper.

由土石流发生机率方程式，推求土石流发生机率－坡度－水位曲线，并藉以探讨参数之变异系数对土石流发生机率之影响，及评估土层在水位、坡度的变化下，土石流之发生机率。

At the mean time higher dose increased its endure tolerance. 2. Extracting DNA from small sized insect proved that the size of the green peach aphid's genome DNA is about 21 kb.

此结果从分子水平证明处理F2代桃蚜的DNA发生了变异，揭示出紫外诱导可遗传的变异，且变异大小是由辐射时间和辐射强度共同决定。

The absorption and distribution of chromium were studied in ryeusing nutrient culture technique and pot experiment.

采用不同浓度K2CrO4(0，0.4，0.8和1.2 mmol/L)的Hoagland营养液处理黑麦幼苗，测定铬在黑麦体内的亚细胞分布、铬化学形态及不同部位的积累。

By analyzing theory foundation of mathematical morphology in the digital image processing, researching morphology arithmetic of the binary Image, discussing two basic forms for the least structure element: dilation and erosion.

通过分析数学形态学在图像中的理论基础，研究二值图像的形态分析算法，探讨最小结构元素的两种基本形态：膨胀和腐蚀；分析了数学形态学复杂算法的基本原理，把数学形态学的部分并行处理理念引入到家实际应用中。