A Study on the Phylogeny of the Dyer's Woad Rust Fungus and Other Species of Puccinia from Crucifers.

ABSTRACT The identity of a Puccinia species occurring on the introduced weed dyer's woad (Isatis tinctoria) was studied using sequences from the internal transcribed spacer of the nuclear ribosomal DNA. The relationship of this fungus to other Puccinia species occurring on the family Brassicaceae in Europe and North America was examined, and we tested the hypothesis that P. thlaspeos and P. monoica are correlated species. The data suggest that the Puccinia species from dyer's woad is closely related to the North American species P. consimilis and may be derived from an indigenous strain of P. consimilis that switched hosts. Thus, the Puccinia species from dyer's woad is probably native to North America and is unlikely to cause disease epidemics on indigenous plants if used as a biological control agent against dyer's woad. P. thlaspeos appears to be polyphyletic and, therefore, P. thlaspeos and P. monoica do not appear to be correlated species. Additional DNA sequence data will be needed to clarify further the phylogeny of Puccinia species on the family Brassicaceae.

Phylogenetic relationships of dennstaedtioid ferns: evidence from rbcL sequences.

The ferns are an ancient group of vascular plants that have yielded a staggering array of systematic problems. Among fern classifications, the number of genera in some families has ranged over 10-fold, and some genera have been treated in up to five different families. Three main groups of leptosporangiate ferns have been recognized; the adiantoid, polypodioid, and dennstaedtioid lines. To clarify relationships among genera and families of dennstaedtioid ferns, we sequenced 1320 bp of the chloroplast gene rbcL from 45 species representing 13 families. Sequence divergence for rbcL averaged 0.9% among species within genera, 10.3% among genera within families, and 14.8% among families, suggesting that the data are appropriate for phylogenetic analysis at the generic and familial levels in ferns. Maximum parsimony analysis resulted in four shortest trees of equal length. The strict consensus tree supported many aspects of previously published hypotheses of relationship based on morphological and cytological variations. For example, the tree ferns (which form a single clade) and Hymenophyllaceae appear as sister groups to the dennstaedtioid ferns on all shortest trees. However, Polypodiaceae and adiantoid ferns, groups traditionally considered separate from the dennstaedtioid families, emerged within the dennstaedtioid clade. This analysis also suggests relationships of some problematical genera, such as Monachosorum, Calochlaena, and Lonchitis. Examination of additional DNA sequences of nuclear genes and developmental studies are needed to evaluate further the relationships suggested by phylogenetic analysis of rbcL sequence data.

The therapeutic use of albumin.

In this review, we condense and summarize the results of studies on the therapeutic use of human albumin to promote the more efficient use of this costly resource. Reports of major controlled and uncontrolled therapeutic trials, reviews, and summary articles published in English between 1972 and 1991 were identified through library and MEDLINE searches. Case series, prospective studies, and blinded therapeutic trials were identified from the bibliographies of these sources. All sources were critically evaluated for information about the comparative physiologic results and patient outcomes of the therapeutic use of albumin solutions, crystalloid solutions, and volume expanders other than albumin. The therapeutic use of albumin is of marginal benefit for many conditions for which it has been administered, apparently because of the body's capacity to quickly compensate for rapid colloid osmotic shifts. Human studies show little or no demonstrable value for albumin when it is administered for nutritional supplementation, wound healing, perioperative fluid replacement, treatment of early thermal injury, or therapy during extensive retroperitoneal surgery (including aortic aneurysm resection). Therapeutic albumin has well-defined value in several special circumstances: large-volume paracentesis in cirrhotic patients, acute nephrotic syndromes with diuretic resistance, organ transplantation, and plasmapheresis. Additional studies are needed to compare the efficacy of albumin with other volume expanders. For most purposes, balanced crystalloid solutions are satisfactory substitutes for colloid volume expanders and can be obtained at a fraction of the cost of colloid volume expanders.

Electrophoretic Evidence for Genetic Diploidy in the Bracken Fern (Pteridium aquilinum).

Analysis of isozyme variability demonstrates that bracken fern (Pteridium aquilinum) has a diploid genetic system and expresses solely disomic inheritance patterns. Electrophoretic data indicate that genetically variable progeny are produced in natural populations after intergametophytic mating rather than by a process involving recombination between duplicated unlinked loci. Although some enzymes are encoded by more than one locus, this has resulted from subcellular compartmentalization of isozymes, and there is no evidence of extensive gene duplication resulting from polyploidy. The conclusions reached in this report differ from those which propose polyploidy as an adaptive mechanism for maintaining genetic variability in Pteridium and other homosporous pteridophytes.