番茄耐盐体细胞变异体的离体筛选

以上海主要栽培番茄品种“鲜丰”的下胚轴作为外植体诱导愈伤组织 ,用 Na Cl进行直接高盐胁迫和逐渐加大盐浓度胁迫筛选。研究结果表明 ,逐渐加大 Na Cl浓度胁迫筛选获得的耐盐性大多属生理适应性 ,直接高盐胁迫筛选才有可能获得真正的耐盐突变体。直接高盐胁迫筛选再生出的 1 2株耐盐植株 ,在 1 5 0 mmol/L Na Cl的盐胁迫下 ,幼苗的成活率可达6 6 % ,而未经胁迫筛选过的原始株成活率则为零。其中 ,2株耐盐突变株能正常开花、结果。其后代在盐胁迫培养基中芽体的生根率。

玉米抗除草剂体细胞变异体的筛选及植株再生

将玉米优良自交系齐 31 9和N1 0 - 6产生的胚性愈伤组织 ,转移到加有半致死浓度除草剂绿磺隆的培养基上 ,经 3代筛选 ,获得抗除草剂愈伤组织。在加有除草剂的分化培养基上 ,抗性愈伤组织分化出植株。除草剂对愈伤组织的生长与分化有显著影响。再生植株移栽成活后 ,自交结实 ,获得种子。再生植株农艺性状与对照相似。除草剂抗性鉴定结果表明 。

抗茎腐病的玉米（Zea maysL．）自交系体细胞变异体选择

用玉米自交系综３、综３１、５００３、Ｐ９－１０（Ｚｅａ ｍｅｙｓ Ｌ）的幼胚所诱导的愈伤组织，在继代繁殖后一部分愈伤组织转移到含有玉米茎腐病的病原菌（Ｆ．ｇｒａｍｉｎｅａｒｕｍ）毒素的培养基中培养并进行变异体选择，现已获得了大量的抗毒素变异体再生植株，并有部分植株移栽成活。

柑橘抗寒细胞变异体的获得及其抗性遗传稳定性的研究

锦橙（Citrussinensis（L．）Osbeckcv．Jincneng）珠心愈伤组织悬浮细胞通过γ射线诱变与高浓度羟脯氨酸离体选择的方法，获得了抗性细胞系，并再生植株。抗性细胞系及其再生植株比供体（对照）的抗寒性分别提高1．4℃和24℃，连续3年测定结果表明再生植株抗寒性的增强是稳定的。其叶片总DNA的RAPD分析说明供体与变异植株可能在DNA水平上存在细微的差异，冷驯化进一步加强抗性细胞系与再生植株在抗氧化酶SOD、过氧化氢酶（CAT）活性和脯氨酸（Pro）、丙二醛含量上的差异。变异系抗性增强的生理基础涉及Pro代谢外的其他途径，抗氧化酶活性的提高与其抗寒性的增强有关。

Organ-specific enhancement of metastasis by spontaneous ploidy duplication and cell size enlargement

Aneuploidy is commonly observed in breast cancer and is associated with poor prognosis. One frequent type of aneuploidy, hypertetraploidy, may derive from ploidy duplication of hyperdiploid cells. However, the pathological consequences of ploidy duplication in breast cancer progression have not been characterized. Here, we present an experimental system demonstrating spontaneous appearance of hypertetraploid cells from organ-specific metastatic variants of the MDA-MB-231 breast cancer cell line through ploidy duplication in vitro and in vivo. The hypertetraploid progenies showed increased metastatic potential to lung and brain, but not to bone, which may be partially explained by the distinct capillary structures in these organs that confer differential lodging advantages to tumor cells with enlarged size. Our results suggest a potential mechanistic link between ploidy duplication and enhancement of metastatic potentials, as was observed in previous clinical studies of breast cancer.