New approaches to mutagenicity studies in animals for carcinogenic and mutagenic agents. I. Modification of the heritable translocation test

Abstract

Two alternative modifications of the experimental protocol for the heritable translocation test are described. One of them proposes to mate F1 males and F1 females within one experimental group and eliminate normal pairs by a sequential decision procedure based on litter sizes. Pairs that do not meet the criteria for normal litter size have to be separated and tested against normal partners. Male translocation suspects are analyzed cytogenetically for presence of a reciprocal translocation. Female translocation suspects or XO suspects are verified through analysis of their male and female progeny. The second modification of the heritable translocation test omits fertility testing and proposes to cytogenetically analyze 25 diakineses-metaphases I from each F1 male in the test. Using either one or both protocols it was shown that 20 mg/kg of methyl methanesulfonate (MMS) induced 1.3% heritable translocations in late spermatids and early spermatozoa. With 2.5 mg/kg of mitomycin C, 0.3% and 0.4% translocation carriers were recovered from treated primary spermatocytes and early spermatids, respectively. A dose of 300 R gamma rays resulted in 1.6% translocations in spermatozoa and 4.8% translocations in primary spermatocytes. The advantage of the modified fertility test lies in the doubling of the sample size by including the females. However, a disadvantage is the amount of time and labor that is necessary to verify female translocation carriers. The cytogenetic translocation test protocol with all F1 males is considered more reliable and faster. It lacks the possibility of error entailed in the decision procedure by fertility testing, and it requires less time, personnel, and animal space.

Germ cell-specific decrease of acrosomal proteolytic activity, sperm motility, and number in mitomycin C-treated mice

“…The MC action in preleptotene-late-spermatogonial cells, as well as in earlier cell stages, may be contrasted with its inaction in spermatozoa and spermatids (3 and 5 weeks; Table I). A similar pattern of cell specificity is found for MC's mutagenicity, clastogenicity, and cell toxicity [1,2,5,18,19].…”

“…We propose the hypothesis that induced loss of sperm motility and acrosomal proteolytic activity in single spermatozoa derived from MC-treated spermatogonial cells (7 and 10 weeks; Table I) is caused by mutational or developmental effects, whereas in preleptotene-derived and late-spermatogonium-derived sperm similar dysfunction results from developmental effects. That MC is capable of inducing gene and chromosomal mutation in spermatogonial cells is well documented [ 1,2,5,18]. Since treated spermatogonial stem cells undergo 3-6 mitotic cell cycles before entering meiosis [4], it is unlikely that a transcriptionally or posttranscriptionally altered developmentally important gene product would be carried through these divisions to cause dysfunction in the spermatozoa.…”

Mechanisms and consequences of paternally‐transmitted chromosomal abnormalities

“…Gray boxes represent period of sterility induced after exposure. Original data was presented in the following works (listed by mutagen): acrylamide (Shelby et al, 1986, 1987; Adler et al, 1994a), busulfan (Ehling and Neuhauser‐Klaus, 1991), benzo[a]pyrene (Generoso et al, 1982), 1,3‐butadiene (Adler et al, 1998), chlormbucil (Generoso et al, 1995), chlormethine (Fox and Scott, 1980; Ehling and Neuhauser‐Klaus, 1989), cyclophosphamide (Sotomayor and Cumming, 1975; Ehling and Neuhäuser‐Klaus, 1988), dacarbazine (Adler et al, 2002), diepoxybutane (Adler et al, 1995), ethylene oxide (Generoso et al, 1986, 1990), ethyl methanesulphonate (Cattanach et al, 1968; Ehling et al, 1968), ethyl nitrosourea (Generoso et al, 1984), etoposide (Bishop et al, 1997), glycidamide (Generoso et al, 1996), isopropyl methanesulfonate (Ehling and Neuhäuser‐Klaus, 1995; Generoso et al, 1979a), melphalan (Generoso et al, 1995), 6‐mercaptopurine (Generoso et al, 1975), methyl methanesulfonate (Lang and Adler, 1977), methyl nitrosourea (Generoso et al, 1984), mitomycin C (Ehling, 1971; Adler, 1980), procarbazine (Ehling, 1974; Adler, 1980), triethylenemelamine (Cattanach, 1957; Bateman, 1960), trophosphamide (Adler et al, 1994b; Ehling and Neuhäuser‐Klaus, 1994), and X‐rays (Ehling, 1971; Searle et al, 1974).…”

Spermatogenesis and mutagenicity of environmental hazards: extrapolation of genetic risk from mouse to man

“…Progeny of both sexes are mated at the age of 10–12 weeks within the experimental groups avoiding brother–sister matings. To determine possible translocation heterozygotes by reduced fertility, a sequential decision procedure of eliminating pairs with normal litters is employed ( Adler, 1980). Up to three litters are observed before pairs with reduced litter size or pairs without any litter are separated.…”