Nuclear volumes, DNA contents, and radiosensitivity in whole-body-irradiated amphibians.
Nuclear volumes, DNA contents, and radiosensitivity in whole-body-irradiated amphibians.
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全身照射两栖动物的核体积、DNA 含量和放射敏感性。
DOI：
10.2307/3573867
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发表时间：
1973
影响因子：
3.4
通讯作者：
J. Clinton
中科院分区：
文献类型：
--
作者：
A. D. Conger;J. Clinton
核参数，以及一些物种的平均存活时间。在少数物种中，一些个体的肝细胞中存在可检测到的多倍体亚群。核体积和染色体体积(NV和ICV)与DNA含量呈线性关系。平均而言，对于25种两栖动物来说，核DNA含量每增加1.0m~3，Nv就会增加17jAm3，当DNA含量减少到0时，剩余Nv就会增加72 jam3。很明显，两栖类NV和ICV的很大一部分(约80%)是非染色体的，即核“汁液”。NV测量的实际基因组大小和估计的基因组大小之间的差异可能解释了在相同测量的NV或ICV下，两栖动物和其他高等生物之间辐射敏感性的一些差异。全身照射的两栖动物死亡非常慢，需要70到150天才能完成辐射诱导的死亡，平均存活时间(MST)在31-190天。MST随核参数尺寸的增大而增大，但变异性较大。有三种明显的死亡模式(三组分MST-剂量曲线)。在最小LD50时，动物死于造血死亡；更大剂量的死亡机制并不明显，但不是肠道损伤。LD50随着核参数尺寸的增加而减小，但不是线性的，所分析的八种物种的斜率为-0.58(NV的13倍范围)。敏感性3体积数据仅适用于其他两组全身照射的生物体。在同一ICV，两栖动物对辐射的敏感性大约是草本植物的7倍，大约是木本植物的3倍。与以前在高等生物的单细胞系统中发现的四个辐射敏感组(放射性分类群)相比，这些全身照射的两栖动物的DO与ICV的相关性非常接近于包含两栖动物的单细胞组的DO-ICV关联线。
with nuclear parameters, and on mean survival times for a number of species. In a few species, some individuals have detectable polyploid subpopulations in their liver cells. Nuclear and chromosomal volumes (NV and ICV) are linearly related to DNA contents. On the average, for 25 amphibian species an increase of 1.0 ,m3 in nuclear DNA content causes an increase of 17 jAm3 in NV, and residual NV is 72 jum3 when DNA content goes to zero. It is clear that a large fraction (about 80%) of amphibian NV and ICV is nonchromosomal, i.e., is nuclear "sap." This difference between actual genome size and its estimate as measured by NV may account for some of the difference in radiosensitivity, at the same measured NV or ICV, between amphibians and other higher organisms. Whole-body-irradiated amphibians are very slow to die, requiring 70 to >150 days to complete radiation-induced deaths, with mean survival times (MST) at the LDr0 of 31-190 days. MST increases with increasing nuclear parameter size, but variability is high. Three modes of death (a three-component MST vs dose curve) are apparent. At the minimal LD50, animals die of a hematopoietic death; the mechanism for death at greater doses is not apparent, but is not intestinal damage. LD50 decreases with increasing nuclear parameter size, but less rapidly than linearly, with a slope of -0.58 for the eight species analyzed (13-fold range of NV). Sensitivit3volume data are available for only two other groups of whole-body-irradiated organisms. At the same ICV, amphibians are about seven times as radiosensitive as herbaceous plants, about three times as sensitive as woody plants. Compared to the four radiosensitivity groups (radiotaxa) found previously among single-cell systems from higher organisms, the correlation of Do against ICV for these whole-body-irradiated amphibians falls very close to the Do-ICV correlation line for the single-cell group which contained amphibians.