Multiple nuclear-gene phylogenies: application to pinnipeds and comparison with a mitochondrial DNA gene phylogeny

Phylogenetic analyses of closely related species should use information from multiple, independent genes with relatively high rates of sequence evolution. To investigate species for which there are few prior sequence data for single-copy nuclear (scnDNA) genes, primers for gene amplification can be designed to highly conserved regions of exons in order to amplify both coding (exons) and noncoding (introns) sequences. We have explored this approach in a phylogenetic analysis of six species of pinnipeds that, together with terrestrial carnivore outgroups, encompass divergence times < or = 40-50 Mya. We sequenced one intron from each of the aldolase A (ALD-A), aldolase C (ALD-C), and histone H2AF genes; one exon from the major-histocompatibility-complex DQA gene; a H2AF processed pseudogene (psi H2AF); and, for comparison with the nuclear genes, the 5' portion of the mitochondrial DNA (mtDNA) control region. The pinniped psi H2AF genes were found to be of limited use because they were paralogous with the gene in the outgroup. The rate of silent substitution in scnDNA (primarily introns) was 5-10-fold lower than that for mtDNA control region I, and scnDNA sequence divergence increased linearly with time < or = 40-50 Mya. Alleles at three polymorphic scnDNA loci (ALD-A, H2AF, and DQA) in the southern elephant seal were paraphyletic with respect to the allele from the closely related northern elephant seal, while the more numerous mtDNA alleles were monophyletic. This we attribute to the consequences of a higher mutation rate rather than to a lower effective population size of mtDNA compared with scnDNA. Within the short (i.e., < 500-bp) sequences of individual scnDNA sequences, phylogenetically informative variation was insufficient to obtain robust phylogenies. However, the combined scnDNA sequences produced a well-supported phylogeny congruent with that derived from mtDNA. This analysis illustrates the high resolution of mtDNA sequences compared with a similar length of scnDNA sequence, but it also demonstrates the utility of combining information from multiple short scnDNA sequences obtained using broadly applicable primers.      

Exchange diffusion of dopamine induced in planar lipid bilayer membranes by the ionophore X537A

The ionophore X537A causes a large increase in the [(14)C]dopamine (a catecholamine) permeability of planar bilayer membranes. Dopamine transport increases linearly with the ionophore concentration. At relatively high concentrations in the presence of dopamine, the ionophore omdices a conductance which is nearly ideally selective for the dopamine cation. However, the total dopamine flux as determined in tracer experiments is not affected by an electric field and is over 10(5) times larger than predicted from the estimated dopamine conductance. Increasing the dopamine concentration on the side containing radioactive dopamine (the cis side) saturates the dopamine transport. This saturation is relieved by trans addition of nonradioactive dopamine, tyramine, H(+), or K(+). With unequal concentrations of dopamine cis and trans (49 and 12.5 mM), the unidirectional dopamine fluxes are equal. Increasing H(+) cis and trans decreases dopamine transport. It is concluded that at physiological pH, the X537A-induced transport of dopamine occurs via an electrically silent exchange diffusion of dopamine cation with another cation (e.g., dopamine(+), H(+), or K(+)). X537A induces a Ca(++)-independent release of catecholamines from sympathetic nerves by interfering with intracellular storage within storage vesicles (R.W. Holz. 1975. Biochim. Biophys. Acta. 375:138-152). It is suggested that X537A causes an exchange of intravesicular catecholamine with a cytoplasmic cation (perhaps K(+) or H(+)) across the storage vesicle membrane.     

ENVIRONMENTAL MODELS FOR PALEOZOIC COMMUNITIES

Nearshore communities in Paleozoic epeiric seas occur in two distinct lateral patterns which parallel shorelines — an expanded pattern of five and a compressed pattern of three laterally adjacent communities. The two community patterns are correlated with two distinct environmental models which are a product of local tectonics. Model 1 (tectonically stable) develops in low slope transgressing epeiric seas. Model 2 (tectonically active) develops in high slope prograding epeiric seas commonly with abundant terrigenous clastic influx. Environmental variables and organic evolution change community constituents, but the broad community patterns recur at least through the early and middle Paleozoic.     

Larval development of the chthamaloid barnacles Catomerus polymerus Darwin, Chamaesipho tasmanica Foster & Anderson and Chthamulus antennatus Darwin (Crustacea: Girripedia)

The presence of embryos in the mantle cavity of Catomerus polymerus, Chamaesipho tasmanica and Chthamalus antennatus was monitored over a two year period. C. polymerus and C. tasmanica show a clearly defined breeding season spanning late autumn, winter and early spring. C. antennatus breeds more continuously throughout the year, with a decline in breeding during the winter. The larval stages of C. polymerus, C. tasmanica and C. antennatus are described from larvae reared in the laboratory. Morphological differences allow each larval stage of the three species to be distinguished without difficulty. Unique larval features permit identification to superfamily, family and genus. The similarities of chthamaloid nauplii to those of lepadomorphs and verrucomorphs and their differences from the nauplii of other balanomorphs are discussed. Larval evidence supports the view that the chthamaloids are related more closely than other balanomorphs to the lepadomorphs, and that the coronuloids and balanoids share a comon derivation from the chthamaloids.     

Transpuparial transmission of Kashmir bee virus and sacbrood virus in the honey bee (Apis mellifera)

When particles of Kashmir bee virus (KBV) and sacbrood virus (SBV) were fed to larvae of the honey bee, Apis mellifera, in Australian colonies, the resulting pupae became in apparently infected. There was no statistically significant difference in the susceptibility of 1, 2, 3 or 4-day-old larvae for either virus, but 5-day-old larvae were significantly less susceptible to SBV than younger larvae. There was no significant difference in the proportions of pupae that became in apparently infected when, as larvae, they were fed various concentrations of each virus, but significantly more larvae were removed from their cells when fed concentrated preparations of each virus than when fed diluted preparations. Susceptible larvae that became in apparently infected with KBV and SBV developed normally into in apparently infected pupae and later, emerged as in apparently infected worker bees.