Sparrow A H, Howard A, Cowie F G, Schwemmer S S, Nauman A F
Int J Radiat Biol Relat Stud Phys Chem Med. 1975 Apr;27(4):343-54. doi: 10.1080/09553007514550311.
Survival curves were constructed and D0 values determined after X-irradiation of single-celled germinating spores of 14 species of ferns, which had a wide variation in interphase chromosome and nuclear volumes and in DNA content per chromosome and per nucleus. A good fit to a line of slope equal to -1 is given on a log-log plot relating D0 to interphase chromosome volume. In a previous publication (Sparrow, Underbrink and Sparrow 1967), ferns fell into radiotaxon VIII, but the new data suggest that they should be assigned to a new group (VIIa) falling midway between radiotaxa VII and VIII. The calculated energy absorption per chromosome at D0 for VIIa is also intermediate between those for VII and VIII. If the value of this parameter is set at 1 for radiotaxon V, that for VIIa is approximately 32 times greater and the radiotaxa V, VI, VII and VIIa form a series 1 : 4 : 14 : 32. The new results indicate that radiotaxon VIII may have to be abandoned unless some other radiobiologically unexplored group (e.g. algae) fills the gap.
构建了存活曲线，并测定了14种蕨类植物单细胞萌发孢子经X射线照射后的D0值，这些蕨类植物在间期染色体和细胞核体积以及每条染色体和每个细胞核的DNA含量方面存在广泛差异。在将D0与间期染色体体积相关的对数-对数图上，数据与斜率等于-1的直线拟合良好。在之前的一篇出版物中（斯帕罗、安德布林克和斯帕罗，1967年），蕨类植物属于放射分类群VIII，但新数据表明它们应被归为一个新的组（VIIa），位于放射分类群VII和VIII之间。VIIa在D0时每条染色体的计算能量吸收值也介于VII和VIII之间。如果将放射分类群V的该参数值设为1，那么VIIa的该值大约大32倍，并且放射分类群V、VI、VII和VIIa形成1 : 4 : 14 : 32的序列。新结果表明，除非某些其他未进行放射生物学研究的类群（如藻类）填补这一空白，否则可能不得不放弃放射分类群VIII。
