Sylvia E. Bartlett

Polymerase chain reaction/direct sequence analysis of the cytochrome b gene in Salmo salar

Abstract The polymerase chain reaction (PCR) and direct sequencing were used to determine the amount of genetic variation in a 295 nucleotide region of the mitochondrial cytochrome b gene of Atlantic salmon ( Salmo salar ). Sixty salmon from nineteen populations, eleven from Europe and eight from North America, were surveyed at this locus. Three genotypes, which differed from each other at either one or two nucleotide positions, were found. Only one genotype was present among the European populations whereas all three genotypes were observed among the North American populations. These results indicate a very low level of intraspecific variation in Atlantic salmon. This is in accordance with findings observed using other biochemical genetic procedures such as mitochondrial DNA restriction fragment analysis and protein electrophoresis. Brown trout ( Salmo trutta ) differed from Atlantic salmon by a maximum of sixteen nucleotide differences over this region. These included fourteen transitions and two transversions, representing 5.4% sequence divergence between the species. Fifteen of the differences were located at third codon positions and one was a first-position change. The amino acid sequences were identical in both species.

A Phylogenetic Perspective on the Evolution of Reproductive Behavior in Pagophilic Seals of the Northwest Atlantic as Indicated by Mitochondrial DNA Sequences

The ice-breeding (pagophilic) habits and relatively short lactation periods of several species of “true” seals (Phocidae) of the Northwest Atlantic, including the harp seal ( Pagophilus ), bearded seal ( Erignathus ), and hooded seal ( Cystophora ), usually are assumed to have evolved in parallel. Current taxonomy regards Pagophilus and ringed seals ( Pusa ) along with harbor seals ( Phoca vitulina ) as subgenera of Phoca , unites Phoca (sensu lato) together with gray seals ( Halichoerus ) and Erignathus in the subfamily Phocinae, and places Cystophora with elephant seals ( Mirounga ) in a separate subfamily, Cystophorinae. Cladistic analysis of variation in the DNA sequence of the mitochondrial cytochrome b gene identifies three clades among northern seals: Phoca-Pusa-Halichoerus, Cystophora-Pagophilus , and Erignathus. Erignathus is the sister group to the other species examined. Each clade may be regarded as a tribe of the subfamily Phocinae (the Phocini, Cystophorini, and Erignathini, respectively). The phylogeny suggests that the ice-breeding habit and associated brief lactation are ancestral characters for the Phocinae and that instances of fast-ice or terrestrial breeding are convergences on the ancestral condition in other phocid subfamilies.

Identification and purification of serum albumin from rainbow trout (Salmo gairdneri)

Abstract 1. 1. Two palmitate-binding serum albumins have been identified in rainbow trout plasma. 2. 2. One of these albumins was purified to homogeneity. 3. 3. Rainbow trout albumins do not bind bromophenol blue or to Blue-sepharose columns. 4. 4. The amino acid composition of rainbow trout albumin suggests that it differs from mammalian albumins in the number of disulphide bridges.