CLADISTICS OF THE BRYOPSIDALES: A PRELIMINARY ANALYSIS

The Bryopsidales contains some of the most species rich and ecologically dominant algae in tropical ecosystems. However, the evolutionary relationships among the 29 genera and several hundred species of this order remain poorly resolved. Because of a lack of known reproductive characters for many taxa, evolutionary hypotheses grouped genera by similarities in morphological characters. To apply standard cladistical analyses to further our understanding of this group, this study presents the first comprehensive compilation of reported morphological, reproductive, and subcellular characteristics for genera in the Bryopsidales. Computer-assisted cladistical analyses ultimately identified phylogenetically informative and uninformative characters. Although the topology of the trees generated in this study is expected to change as additional data are added to this matrix, many traditional groupings and recent groupings based on molecular data were supported.     

Recombinant plasmid conferring proline overproduction and osmotic tolerance.

A recombinant plasmid carrying the proBA (pro-74) mutant allele which governs osmotic tolerance and proline overproduction was constructed by using the broad-host-range plasmid vector pQSR49. The physiological, biochemical, and genetic properties of strains carrying the pQSR49 derivatives pMJ101 and pMJ1, mutant and wild type, respectively, were investigated. pMJ101 conferred enhanced osmotolerance compared with strains carrying the wild type, pMJ1. These results are in contrast to those obtained previously with strains carrying recombinant plasmids based on pBR322 that failed to confer the osmotic tolerance phenotype. gamma-Glutamyl kinase (first step in proline biosynthesis) from strains carrying pMJ101 was 200-fold less sensitive to feedback inhibition than was the wild-type enzyme. As expected, the intracellular proline levels of strains carrying pMJ101 were more than an order of magnitude higher than those of the wild type. An analysis of copy number revealed that the pQSR49 constructs were present in the cell at a level six- to eightfold lower than those of the pBR322 recombinants, which may account for the difference in phenotype. We found that the genetic stability of the pQSR49 derivative in a variety of gram-negative bacteria was dependent on the insert orientation and the presence of foreign DNA on the plasmid. These factors may be significant in future studies aimed at expanding the osmotolerance phenotype to a broad range of gram-negative bacteria.     

Nondormant mutants in a temperate tree species,Corylus avellana L.

Summary Nondormant mutants in hazelnut (Corylus avellana L.) are described. In contrast to normal trees in which physiological rest, or dormancy, is induced by short days, mutants fail to respond to this stimulus. Shoot tips continue to grow, old leaves are retained until midwinter when they are frozen and/or pushed off by developing axillary buds, axillary buds begin to grow in December, 2–3 months before normal spring bud break, and cold hardiness does not develop. Nondormancy is controlled by a single recessive gene (dd). The mutation is not uncommon since eight cultivars, including the world's most important commercial cultivars, are heterozygous for this trait. The implications of nondormancy in a temperate tree species are discussed in relation to evolution, extension of the range of cultivation, breeding, and value for basic studies of fundamental mechanisms of dormancy.     

Rapid RFLP screening procedure identifies new polymorphisms at albumin and alcohol dehydrogenase loci

Summary A rapid screening procedure for restriction fragment length polymorphisms (RFLPs) is reported. DNA from ten individuals is pooled and compared to DNA isolated from a cell line containing a single chromosome 4. This single chromosome-containing line is an obligate hemizygote for chromosome 4 RFLPs so that only one band corresponding to a single allele will appear on a Southern blot. In the pooled DNA sample lane bands corresponding to both alleles will be seen. The technique allows for efficient detection of RFLPs with easier use of large numbers of enzymes. It provides estimates of allele frequencies and disequilibrium. New RFLPs for albumin and alcohol dehydrogenase detected with this technique are described.