No abstract

The European lobster, Homarus gammarus, is a high value species, which is widely distributed from the northern part of Norway to Morocco in North Africa. It is also found throughout the Mediterranean including the Aegean Sea. Knowledge of the genetic structure is necessary for rational management of exploited species. As part of a comprehensive genetic investigation of European lobster (EU-project "Genetics of European Lobster"), 1514 lobsters from 14 locations were analysed for six polymorphic allozyme loci. Despite generally low levels of genetic differentiation (overall F ST = 0.016), the tests for population differentiation revealed highly significant values for all loci investigated. In particular, the lobsters from three areas including northern Norway, the Netherlands, and Aegean Sea in the Mediterranean were genetically different from lobsters from other regions. genetic diversity observed in the samples from other areas, and polymorphism was only detected at the IDHP-1* locus. A new slow-moving allele at the GPI-1* locus was found in the samples from the Aegean Sea. Pairwise F ST comparisons, as well as a UPGMA dendrogram based on Nei's genetic distance (calculated from allele frequencies across the six loci investigated), confirm the separate main groupings.

The purpose of this application is to designate P. multiplicatus Carlgren, 1912 as the type species of the cerianthid genus Pachycerianthus Roule, 1904 in place of the original type species P. beiiedeni Roule, 1904. Only the holotype has ever been assigned to the latter species; this specimen is untraceable and its description does not permit proper interpretation of the genus.

(fig 1). A recombination rate of 5% was used in all risk calculations based on these probes. DNA ANALYSIS DNA (5 to 10 p.g) from the appropriate family members was digested with restriction enzymes according to the manufacturers' instructions. The resulting fragments were size fractionated by electrophoresis in 0.8% agarose gels (Bethesda Research Laboratories). The fragments were transferred to nylon membranes (Hybond-N, Amersham) by the method of Southern8 or by vacuum blotting using the Hybaid Vacuaid system. The DNA was covalently bound to the membrane by UV photocrosslinking (305 nm for 90 seconds). The probe insert was electrophoretically purified and 50 ng was labelled with a 32P-dCTP using the random hexanucleotide primer method of Feinburg and Vogelstein9 (Multiprime Kit, Amersham). Unincorporated nucleotides were removed by gel filtration on a Sephadex G-50 column and the specific activity of the probe was measured by scintillation counting (usually 5 to lOx 108 dpm/tg DNA). The membrane was incubated for a minimum of four hours at 42°C in a formamide based prehybridisation buffer (50% formamide, 0.1% Denhardt's, 1% SDS, 5 x SSPE, 5% dextran sulphate, and 400 [tg/nl sheared salmon sperm DNA). The hybridisation solution was the same without salmon sperm DNA, which was added to the labelled probe before denaturation. The membrane was hybridised at 42°C overnight and then washed in 2x SSPE at room temperature followed by 65°C washes at in-

Linkage disequilibrium and cystic fibrosis (CF) allele segregation were analysed in 46 CF families in Northern Ireland. The smaller (+) allele of the KM19/PstI polymorphism and the larger (-) allele of the XV-2c/TaqI polymorphism showed marked linkage disequilibrium with CF. This information can be used to alter the risk of an individual being a carrier of CF away from the expected population risk of 1 in 20. The high-risk genotypes K+K+ or X-X- have a risk of 1 in 10 and the low-risk genotypes K-K- or X+X+ have a risk of 1 in 50. A study of the segregation of CF alleles in the 46 families, using KM19 and Xv-2c, showed preferential inheritance of the paternal (79%), as opposed to the maternal (21%), CF allele by the heterozygous carriers. A mechanism that might explain this observation is discussed.