Salinas J, Zerial M, Filipski J, Crepin M, Bernardi G
Nucleic Acids Res. 1987 Apr 10;15(7):3009-22. doi: 10.1093/nar/15.7.3009.
Integrated sequences of mouse mammary tumor virus (MMTV) have been localized in the genomes of five inbred mouse strains (Balb/c, C3H, DBA/2, A.TH, 129-SV) and one mammary tumor cell line (GR). Two major classes of MMTV sequences have been detected in mouse DNA fractions as obtained by Cs2SO4/BAMD (3,6-bis-(acetatomercurimethyl)dioxane) density gradient centrifugation. The first one corresponds to previously described endogenous sequences (Mtv loci), whereas the second one corresponds to endogenous sequences not previously known, and/or recently acquired; in the case of GR cells exogenous sequences may also be present in this class. The genome distribution is somewhat different for the two classes of sequences, the first one being practically only present in the lightest DNA segments of the mouse genome (GC congruent to 38%); the second one being also represented in heavier segments (GC congruent to 43%). This integration pattern suggests that "ancient" endogenous sequences are practically only localized in genome segments of roughly matching composition, whereas exogenous and recently acquired endogenous MMTV sequences may also be present in heavier fractions.
小鼠乳腺肿瘤病毒（MMTV）的整合序列已定位在五个近交系小鼠品系（Balb/c、C3H、DBA/2、A.TH、129-SV）和一个乳腺肿瘤细胞系（GR）的基因组中。通过Cs2SO4/BAMD（3,6-双（乙酰汞甲基）二恶烷）密度梯度离心法获得的小鼠DNA组分中检测到了两类主要的MMTV序列。第一类对应于先前描述的内源性序列（Mtv位点），而第二类对应于先前未知的和/或最近获得的内源性序列；就GR细胞而言，这类中也可能存在外源性序列。两类序列的基因组分布有所不同，第一类实际上仅存在于小鼠基因组中最轻的DNA片段中（GC含量约为38%）；第二类在较重的片段中也有体现（GC含量约为43%）。这种整合模式表明，“古老的”内源性序列实际上仅定位在组成大致匹配的基因组片段中，而外源性和最近获得的内源性MMTV序列也可能存在于较重的组分中。
