Homology in coding and non-coding DNA sequences: a parsimony perspective

Putative synapomorphy assessment (primary homology assessment) is distinct for DNA strings having a codon structure (hereafter, coding DNA) versus those lacking it (hereafter, non-coding DNA). The first requires the identification of a reading frame and of usually few in-frame insertions and deletions. In non-coding DNA, where length variation is much more common, putative synapomorphy assessment is considerably less straightforward and highly depends on the alignment method. Appreciating the existence of evolutionary constraints, alignments that consider patterns associated with specific putative evolutionary events are favored. Once the sequences have been aligned, the postulated putative evolutionary events need to be coded as an additional step. In order for the alignments and the alignment coding to be falsifiable, they should be carried out using justified and explicitly formulated criteria. Alternative coding methods for the most common patterns present in alignments of non-coding DNA are discussed here. Simpler putative synapomorphy assessment will not always correlate to more reliable phylogenetic information because simplicity does not necessarily correlate to the degree of homoplasy. The use of non-coding DNA can result in more laborious coding, but at the same time in more corroborated hypotheses, mirroring their accuracy for phylogenetic inference.     

Blütenmorphologische und palynologische Untersuchungen an Littorella

In the monograph of the Plantaginaceae by Pilger (1937) Littorella is looked upon as a genus with three species. The indigenous Littorella uniflora (L.) Aschers. — native to the Atlantic Europe — is closely related to L. americana Fern., distributed in Eastern North America. In South America there occurs the most interesting species, L. australis Griseb., in two part-areas (in Southern Chile near Panguipulli-Lake and more southern near Lake San Martin to Seno de Ultima Esperenza and on Eastern Falkland-Island). Littorella is a perennial water-or swamp plant, growing on sandy and muddy soils. It can be living submersely throughout life without flowering and propagating by runners in this case. Its occurence, the structure of its inflorescence and ovary apparently quite different and the position of the male flower gave repeatedly rise in literature to the opinion, to seperate Littorella and Plantago far from each other. Indeed, in Littorella as well as in Plantago and the third genus Bougueria, native to the Andes of Peru and Bolivia, the leaves are arranged in rosettes, but the steams are extremely compressed. In the first enumerated genera, the axillary leafless main-axis is ending into a spherical to cylindrical ear, whereas in Littorella there is only one male flower (rarely two!) at the base of which there are sitting several female ones. These different opinions on the inflorescence of Littorella and its relationships to Plantago are discussed. In this connection, a flower- and pollenmorphological elaboration of the three species of the genus seemed to be useful. An evaluation of numerous flowers furnished the proof, that, also here, the ostensibly strict fourfoldness of the corolla is broken through and thus, indications for a possible derivation from a pentamere structure of the flower are to be found.     

A pheromone bouquet controls the reproductive behaviour of the male shore crab,Carcinus maenas

Aquatic Ecology - The reproduction of many brachyuran crustaceans involves the formation of mating pairs often around the time of the female moult with attraction of a sexual partner and mating...     

UV-Repair is impaired in fibroblasts from patients with Fanconi's anemia

Summary Fanconi's anemia, a hereditary autosomal disease with chromosomal instability, elevated incidence of cancer and clinical symptoms is accompanied by a DNA repair deficiency. Fibroblasts from patients with Fanconi's anemia were found to be impaired in the DNA repair of UV damage. Nucleoid decondensation and recondensation after UV irradiation were less efficient in fibroblasts from patients with Fanconi's anemia than in those from a healthy proband. These data confirm our earlier findings that DNA ligase is deficient in Fanconi's anemia.