Phylogenetic analysis supports horizontal transfer of P transposable elements

Nucleotide sequence comparisons were used to investigate the evolution of P transposable elements and the possibility that horizontal transfer has played a role in their occurrence in natural populations of Drosophila and other Diptera. The phylogeny of P elements was examined using published sequences from eight dipteran taxa and a new, partial sequence from Scaptomyza elmoi. The results from a number of different analyses are highly consistent and reveal a P-element phylogeny that contradicts the phylogeny of the species. At least three instances of horizontal transfer are necessary to explain this incongruence, but other explanations cannot be ruled out at this time.      

The regulation of body fluid volume in the estuarine annelidNereis succinea

Summary The process of volume readjustment following swelling after transfer to dilute sea water was examined in the estuarine polychaeteNereis succinea by measuring body weight changes. Volume readjustment is an active process that requires O₂ and uninhibited cellular metabolism, and the process is retarded at low temperature. O₂ uptake increases during the swelling phase and remains high throughout the readjustment phase. The intracellular osmolytes lost during volume readjustment include free amino acids, some of which appear to be deaminated and some extruded intact into the medium. Although it is known that intracellular inorganic ions, including Na⁺ and Cl^–, are lost into the extracellular fluid against a concentration gradient, volume regulation in an intact animal is insensitive to a number of drugs that influence ion movements at the cellular level.Two possible mechanisms of extracellular fluid readjustment implicated by previous findings have been eliminated. The increased urine flow known to accompany volume readjustment is not brought about by increased hydrostatic pressure in the coelom. In fact, coelomic fluid pressure decreases, which is consistent with the hypothesis that extracellular volume readjustment is accomplished by enhanced ciliary activity in the nephridia. Removal of the supraesophageal ganglion, an important neuroendocrine organ in annelids, has no effect on organismal volume readjustment.Abbreviations FAA free amino acids - NPS ninhydrin positive substances     

5-methyltetrahydrofolate: synthesis and utilization in normal and SV40-transformed BHK-21 cells.

Dodecyl sulfate complexes of two soluble proteins, serum albumin and fumarase, have been “renatured” with large excesses of the nonionic detergent Triton X-100. The resulting complexes, essentially free of dodecyl sulfate, differ in their sedimentation properties relative to the native protein and in their interaction with Triton X-100. Albumin molecules refold to a form binding only very small amounts of Triton and have a sedimentation coefficient similar to that of the non-denatured protein. On the other hand, refolded fumarase molecules have a lower sedimentation coefficient than that of the native enzyme and bind up to 1.06 mg of Triton/mg protein. It is postulated that the fumarase molecule has been turned “inside-out” by the dodecyl sulfate/Triton treatment, and the implications of such large conformational changes for protein transport across membranes are discussed.     

Phylogeny of the Drosophila saltans species group based on combined analysis of nuclear and mitochondrial DNA sequences

Nucleotide sequences from two nuclear loci, alcohol dehydrogenase and internal transcribed spacer-1 of the nuclear ribosomal DNA repeats, and two mitochondrial genes, cytochrome oxidase I and cytochrome oxidase II, were determined from nine species in the Drosophila saltans species group. The partition homogeneity test and partitioned Bremer support were used to measure incongruence between phylogenetic hypotheses generated from individual partitions. Individual loci were generally congruent with each other and consistent with the previously proposed morphological hypothesis, although they differed in level of resolution. Since extreme conflict between partitions did not exist, the data were combined and analyzed simultaneously. The total evidence method gave a more resolved and highly supported phylogeny, as indicated by bootstrap proportions and decay indices, than did any of the individual analyses. The cordata and elliptica subgroups, considered to have diverged early in the history of the D. saltans group, were sister taxa to the remainder of the saltans group. The sturtevanti subgroup, represented by D. milleri and D. sturtevanti, occupies an intermediate position in this phylogeny. The saltans and parasaltans subgroups are sister clades and occupy the most recently derived portion of the phylogeny. As with previous morphological studies, phylogenetic relationships within the saltans subgroup were not satisfactorily resolved by the molecular data.      

Quantification of angiogenesis in estrogen receptor-positive and negative breast carcinoma

Background

The objective of this study was to evaluate angiogenesis according to CD34 antigen expression in estrogen receptor (ER)-positive and negative breast carcinomas.

Methods

This study comprised 64 cases of infiltrating ductal carcinoma in postmenopausal women divided into two groups: Group A: ER-positive, n = 35; and Group B: ER-negative, n = 29. The anti-CD34 monoclonal antibody was used as a marker for endothelial cells. Microvessel count was carried out in 10 fields per slide using a 40× objective lens (magnification 400×). Statistical analysis of the data was performed using Student's t-test (p < 0.05).

Results

The mean number of vessels stained with the anti-CD34 antibody in the estrogen receptor-positive and negative tumors was 23.51 ± 1.15 and 40.24 ± 0.42, respectively. The number of microvessels was significantly greater in the estrogen receptor-negative tumors (p < 0.001).

Conclusion

ER-negative tumors have significantly greater CD34 antigen expression compared to ER-positive tumors.

     

Platypus globin genes and flanking loci suggest a new insertional model for beta-globin evolution in birds and mammals

Background  

Vertebrate alpha (α)- and beta (β)-globin gene families exemplify the way in which genomes evolve to produce functional complexity. From tandem duplication of a single globin locus, the α- and β-globin clusters expanded, and then were separated onto different chromosomes. The previous finding of a fossil β-globin gene (ω) in the marsupial α-cluster, however, suggested that duplication of the α-β cluster onto two chromosomes, followed by lineage-specific gene loss and duplication, produced paralogous α- and β-globin clusters in birds and mammals. Here we analyse genomic data from an egg-laying monotreme mammal, the platypus (Ornithorhynchus anatinus), to explore haemoglobin evolution at the stem of the mammalian radiation.     

Rat pleural mesothelial cells adapted to serum-free medium as a model for the study of growth factor effects

Mesothelial cells are the putative progenitors of mesotheliomas and cell lines have been used as tools to study the responses of these cells to various stimuli, including growth factors. The present study was undertaken to develop a rat mesothelial cell line capable of sustained growth under serum-free conditions with the object of avoiding the possible confounding effects of undefined serum components. Responses of mesothelial cells to epidermal growth factor were shown to differ under serum-free versus low-serum culture conditions. In contrast, a cell line, SFM1, adapted to growth in serum-free medium was characterized and found to exhibit responses to growth factors similar to the responses reported for human cell lines. This new line should prove to be a useful model for the study of these cells in vitro .