DDT (dicophane) and postmenopausal breast cancer in Europe: case-control study.

OBJECTIVE: To examine any possible links between exposure to DDE (1,1-dichloro-2,2-bis (p-chlorophenyl)ethylene), the persistent metabolite of the pesticide dicophane (DDT), and breast cancer. DESIGN: Multicentre study of exposure to DDE by measurement of adipose tissue aspirated from the buttocks. Laboratory measurements were conducted in a single laboratory. Additional data on risk factors for breast cancer were obtained by standard questionnaires. SETTING: Centres in Germany, the Netherlands, Northern Ireland, Switzerland, and Spain. SUBJECTS: 265 postmenopausal women with breast cancer and 341 controls matched for age and centre. MAIN OUTCOME MEASURE: Adipose DDE concentrations. RESULTS: Women with breast cancer had adipose DDE concentrations 9.2% lower than control women. No increased risk of breast cancer was found at higher concentrations. The odds ratio of breast cancer, adjusted for age and centre, for the highest versus the lowest fourth of DDE distribution was 0.73 (95% confidence interval 0.44 to 1.21) and decreased to 0.48 (0.25 to 0.95; P for trend = 0.02) after adjustment for body mass index, age at first birth, and current alcohol drinking. Adjustment for other risk factors did not materially affect these estimates. CONCLUSIONS: The lower DDE concentrations observed among the women with breast cancer may be secondary to disease inception. This study does not support the hypothesis that DDE increases risk of breast cancer in postmenopausal women in Europe.     

Sarsicopia polaris gen. et sp.n., the first platycopioida (Copepoda: Crustacea) from the Arctic Ocean,and its phylogenetic significance

A new genus of Platycopioida is described from a boxcore sample taken at a depth of 534 m in the ArcticBarents Sea. This is the deepest record ofPlatycopioida so far. Sarsicopia gen. n. is thesistergroup of a taxon comprising Platycopia and Nanocopia; the sistergroup ofthese is Antrisocopia. Sarsicopia gen. n.is the only platycopioid to retain 2 inner setae onthe second endopod segment P2–P4, and 8 setae in thethird endopod segment of P2. The male antennnule isremarkable in having a geniculation located betweenancestral segments XX and XXI. It is suggested thatthis flexure zone was already present in thegroundpattern of Copepoda. Platycopia and Nanocopia have secondarily lost thisgeniculation.     

An autosomal dominant retinitis pigmentosa family with close linkage to D7S480 on 7q

Retinitis pigmentosa is the most prevalent inherited disorder of the retina. It can be autosomal dominant (adRP), autosomal recessive (arRP) or X-linked (XLRP). A form of adRP mapping to chromosome 7q was reported in a large Spanish pedigree. We have typed DNA from the members of another Spanish family for polymorphic markers from the known candidate genes. Positive lod scores were obtained only for the markers located on 7q31-35, giving a maximum lod score of 2.98 (3.01 by multipoint analysis) at = 0.00 for D7S480. A brief clinical evaluation is given.     

Formation of domoic acid and fatty acids inPseudonitzschia pungens f.multiseries with scale of culture

Pseudonitzschia pungens f.multiseries was cultured in 20-L polycarbonate carboys, 350-L fibreglass columns and 500-L plastic bags to determine the effects of medium enrichment and scale of culture on cell yield, production of cellular domoic acid and formation of fatty acids, particularly the potential tracer acid 16:4n-1. Cell concentrations were highest in seawater enriched with stock levels of nitrate and phosphate, but with double the stock level of silicate, at all scales of culture. Cellular toxin in 20, 350 and 500-L cultures averaged 0.32, 0.04 and 2.56 pg cell^-1 and was independent of medium used. The order of magnitude difference in levels of cellular toxin was considered to reflect the varying levels of irradiance within the culture vessels. Support was given to this by the significant difference in content of total cellular fatty acids, due principally to the algal storage acid 16: 1n-7, which is known to be influenced by irradiance. Levels of cellular domoic acid correlated significantly with total fatty acids in 350 and 500-L cultures. Bag cultures producing significantly higher levels of cellular domoic acid provided lower relative proportions of 16:4n-1, which limited its use as a tracer for food-web studies.     

Allozyme variability and phylogenetic relationships in the cultivated potato (Solanum tuberosum) and related species

Gene frequencies at 13 isozyme loci were determined in three South American taxa of cultivated potatoes [the diploid group (gp.) Stenotomum, the diploid subgroups (subgp.) Goniocalyx, and the tetraploid gp. Andigena ofS. tuberosum], in the diploid weed speciesS. sparsipilum, and in most of the main cultivars now raised in the Northern Hemisphere (the tetraploid gp. Tuberosum ofS. tuberosum). High levels of genetic variability (mean number of alleles per locus, percentage of polymorphic loci, and mean heterozygosity) were detected, being higher in tetraploid potatoes. An equilibrium among the evolutionary factors which increase genetic variability and artificial selection for maximum yield would explain the high uniformity of heterozygosity values we observed in both Andigena (0.36 ± 0.02) and Tuberosum (0.38 ± 0.01) cultivars.—The low value of genetic distance (D = 0.044) between Stenotomum and Goniocalyx does not support the status of species forS. goniocalyx.—In most isozyme loci, the electromorphs of gp. Andigena were a combination of those found in both gp. Stenotomum andS. sparsipilum, suggesting an amphidiploid origin of gp. Andigena from that two diploid taxa. The presence in Andigena of unique electromorphs, which were lacking in both gp. Stenotomum andS. sparsipilum, suggests that other diploid species could be also implied in the origin of tetraploid Andean potatoes. Furthermore, since Andigena were more related to Stenotomum (D = 0.052) than toS. sparsipilum (D = 0.241), the autopolyploidization of Stenotomum individuals and the subsequent hybridization with gp. Andigena may also have occurred. Thus, our study suggests a multiple origin (amphidiploidy, autoploidy, and hybridization at tetraploid level) of gp. Andigena.—Most of the electromorphs of gp. Tuberosum were also found in gp. Andigena; both the direct derivation of that group from the Andean tetraploid potatoes and the repeated introgression provided by breeding programmes could explain this result. However, the allele c of Pgm-B, present in 30 out of 76 Tuberosum cultivars from Northern Hemisphere as well as in 3 Chilean Tuberosum cultivars, lacks in the 258 Andigena genotypes sampled, suggesting that Chilean germplasm could have taken part in the origin of at least the 39% of the potato cultivars from Europe and North America analyzed here.—The distanceWagner procedure provides an estimate of a 30% of heterogeneity in the evolutionary divergence shown by different groups of cultivated potatoes. Diploid groups show a higher (22.5%) evolutionary rate than tetraploids, which can be attributed to both tetrasomic inheritance and facultative autofecundation that exists in Andigena and Tuberosum groups. Thus, artificial selection acting since 10000 years has not resulted in a higher rate of molecular evolution at the isozyme level in the tetraploids.     

Partial deletion of 4p16 band in a ring chromosome and wolf syndrome

Summary A new case of ring chromosome 4 in a 2-day-old female child with multiple malformations is described. By means of the GTG-banding technique, a karyotype 46,XX,r(4), (p16q35) was determined. The characteristics of the child's karyotype and the relationship with the structure of the chromosome, especially the location of the deletion that produces the syndrome, are compared with previous reports.     

Genetic Basis of Vi Antigen Expression in Salmonella paratyphi C

Analysis of hybrids formed in a cross between a Salmonella paratyphi C Hfr and an S. typhimurium recipient indicated that the structural genetic determinants of the S. paratyphi C Vi antigen are located closely adjacent to the mel determinant, between this marker and purA. A similar location was indicated for the structural genetic determinants of the S. typhi Vi antigen (the viaB locus) by the results of a mating in which a hybrid S. typhimurium Hfr bearing the S. typhi viaB determinants was used to transfer these genes to an S. typhimurium recipient. Mating experiments with a Vi-antigen-expressing S. typhi Hfr and an S. typhimurium hybrid recipient expressing the Vi antigen of S. paratyphi C yielded no recombinants in which loss of Vi antigen expression occurred, indicating that the chromosomal locus occupied by the genetic determinants of the S. paratyphi C Vi antigen is the same one at which, in S. typhi, the viaB genes reside. Introduction of a mutant S. typhi viaA gene into an S. typhimurium hybrid expressing the Vi antigen, as the consequence of prior receipt of the S. paratyphi C viaB determinants, resulted in that hybrid's loss of Vi antigen expression, demonstrating that the viaA determinant plays a role in Vi antigen expression in S. paratyphi C, as well as in S. typhi. Although the percentages of coinheritance of the viaB and mel determinants in the mating experiments suggested that their linkage is sufficiently close to allow cotransduction by P22, attempts to accomplish this with lysates prepared on S. typhimurium hybrids expressing either S. typhi or S. paratyphi C viaB determinants were not successful.