Environmental and Molecular Mutagenesis - Legacy Tobacco ...

501
ANTIMUTAGENIC FACTORS IN VARIOUS AQUATIC PLANTS .
T . Sato, Y . Ose, H . Nagase and H . Kito, Gifu Pharmaceutical University,
Gifu City, Gifu 502 (•dlrpan)
Various aquatic plants were collected from Nagara River system and
the inhibitory effect of water extracts of the plants on mutagen-induced
mutations were investigated by the Ames test (Salmonella tYChimurium
TA100 and 98) . Smartweed, curled pondweed, Tuiopean cul- -grass an'a
grass-wrack pondweed showed strong antimutagenic effect on benzo(a]pyrene
(B[a]P), but had not for AF-2 . For 2-nitrofluorene (2-NF),
curled pondweed, Europea.n cut-graju and grass-wrack pondweed had the
antimutagenic effect, but smartweed had not . These antimutagenic factors
were heat-resistant . The molecular weight of antimutagenic factor in
curled pondweed and grass-wrack pondweed was above 300,000 . Four
extracts did not show bioantimutagenicity . The active factors of curled
pondweed, smartweed and grass-wrack pondweed acted as desmutagens .
However, the active factor of European cut-grass did not show activity
by desmutagen test, and not inhibit spontaneous mutation and S9 mix .
The contribution of chlorophyll on antimutagenesis was little . B[a]P
was treated by various amounts of the extracts and extracted by ethyl
acetate . The extracted B[a]P decreased with the amount of plant
extract . Almost all of adsorbed B[a]P was released with twice 20 min
ultrasonication . By these results, it became clear that different
antimutagenic factors exist in various aquatic plants .
502
APPROACHES TO DNA METHODS FOR THE DETECTION OF HERITABLE MUTATIONS IN HUMANS .
C . Satoh, K . Hiyama, N . Takahashi and M . Kodaira .
Radiation Effects Research Foundation . Hiroshima 732, Japan
.
We have examined feasibility of ribonuclease A cleavage at mismatches in RNA :DNA
duplexes (RNase A method) and denaturing gradient gel electrophoresis (DGGE) of
RNA :DNA duplexes for a study determining ns~leotide mutation rates . Identical
RNA :DNA duplexes made by hybridization of P-labeled RNA probes and target DNAs
were used in both techniques . Employing the RNase A method, 10 types of mismatches
were examined in duplexes less than 771 bp made from cloned human $-globin genes and
8 of them were cleaved . Deletion and insertion of 1, 4, 5 and 10 bp were detected .
A polymorphic substitution of T to C at position 666 of IVS2 of P-globin gene was
detected in genomic DNAs of 59 Japanese after amplification by polymerase chain
reaction (PCR). Using DGGE, 8 types of mismatches were examined and all of them
were detected . The deletions and insertions detected by the RNase A cleavage method
were also detected. Three different polymorphic substitutions and a variable-length
polymorphism [(ATTTT)n, n - 4 . 5, 6, 7] in the globin genes of 59 Japanese were
detected in the genomic DNAs without amplifica~ion . Any large program screening for
mutations requires examining of the order of 10 person .probe determinations. We
are studying ways to optimize efficiency and cost effectiveness. These 139lude the
use of multiple probes on a single DGGE gel and eliminating the need for P-labeled
probes by the PCR technique .
503
MECHANISMS OF CHROMOSObIE ABERRATION
John R .K . Savage, HtC Radiobioloqy Unit, Chilton, Didcot, Oxon . OX11 ORD . U .K .
The subject of mechanisms has to be considered at several levels and not confined
just to the initial molecular lesions and their repair/misrepair . Although there are
many kinds of lesions which can be introduced by a wide variety of agents and there
are many proposed pathways by which a cell can deal with them, there is only a
limited number of ways in which "rejoining" can occur to produce structural changes
visible in chromosomes at metaphase . This makes chromosomal aberrations a somewhat
non-specific end point . Irrespective of the lesion types and their products, at some
stage in time, some of them must come into "physical contact" if exchange is to
occur . Is such contact predisposed? Are all regions vulnerable? Nhat is the
relationship to and influence of chromatin structure and intranuclear architecture to
such events? The many orders of magnitude difference between the molecular events
and the observed result must not be forgotten, for the complex process of chromosome
condensation and packing which intervenes, leads to aberration modification and
disguise . Some mechanism must also exist to cope with entanglement, for even in the
most complicated of,aberrations, this is a very rare phenomenon . Comments and
observations will be made on these and other topics within the context of
"mechanisms" .
http://legacy.library.ucsf.edu/tid/clb93d00/pdf
1989 EMS Abstracts 173
Notes