The karyotype of Alligator mississippiensis,and chromosomal mapping of the ZFY/X homologue,Zfc

Comparative mapping studies of X-linked genes in mammals have provided insights into the evolution of the X chromosome. Many reptiles including the American alligator, Alligator mississippiensis, do not appear to possess heteromorphic sex chromosomes, and sex is determined by the incubation temperature of the egg during embryonic development. Mapping of homologues of mammalian X-linked genes in reptiles could lead to a greater understanding of the evolution of vertebrate sex chromosomes. One of the genes used in the mammalian mapping studies was ZFX, an X-linked copy of the human ZFY gene which was originally isolated as a candidate for the mammalian testis-determining factor (TDF). ZFX is X-linked in eutherians, but maps to two autosomal locations in marsupials and monotremes, close to other genes associated with the eutherian X. The alligator homologue of the ZFY/ZFX genes, Zfc, has been isolated and described previously. A detailed karyotype of A. mississippiensis is presented, together with chromosomal in situ hybridisation data localising the Zfc gene to chromosome 3. Further chromosomal mapping studies using eutherian X-linked genes may reveal conserved chromosomal regions in the alligator that have become part of the eutherian X chromosome during evolution.     

Paleomicrobiology: Revealing Fecal Microbiomes of Ancient Indigenous Cultures

Coprolites are fossilized feces that can be used to provide information on the composition of the intestinal microbiota and, as we show, possibly on diet. We analyzed human coprolites from the Huecoid and Saladoid cultures from a settlement on Vieques Island, Puerto Rico. While more is known about the Saladoid culture, it is believed that both societies co-existed on this island approximately from 5 to 1170 AD. By extracting DNA from the coprolites, followed by metagenomic characterization, we show that both cultures can be distinguished from each other on the basis of their bacterial and fungal gut microbiomes. In addition, we show that parasite loads were heavy and also culturally distinct. Huecoid coprolites were characterized by maize and Basidiomycetes sequences, suggesting that these were important components of their diet. Saladoid coprolite samples harbored sequences associated with fish parasites, suggesting that raw fish was a substantial component of their diet. The present study shows that ancient DNA is not entirely degraded in humid, tropical environments, and that dietary and/or host genetic differences in ancient populations may be reflected in the composition of their gut microbiome. This further supports the hypothesis that the two ancient cultures studied were distinct, and that they retained distinct technological/cultural differences during an extended period of close proximity and peaceful co-existence. The two populations seemed to form the later-day Taínos, the Amerindians present at the point of Columbian contact. Importantly, our data suggest that paleomicrobiomics can be a powerful tool to assess cultural differences between ancient populations.     

Free Edges in Epithelial Cell Sheets Stimulate Epidermal Growth Factor Receptor Signaling

The ability of epithelia to migrate and cover wounds is essential to maintaining their functions as physical barriers. Wounding induces many cues that may affect the transition to motility, including the immediate mechanical perturbation, release of material from broken cells, new interactions with adjacent extracellular matrix, and breakdown of physical separation of ligands from their receptors. Depending on the exact nature of wounds, some cues may be present only transiently or insignificantly. In many epithelia, activation of the epidermal growth factor receptor (EGFR) is a central event in induction of motility, and we find that its continuous activation is required for progression of healing of wounds in sheets of corneal epithelial cells. Here, we examine the hypothesis that edges, which are universally and continuously present in wounds, are a cue. Using a novel culture model we find that their presence is sufficient to cause activation of the EGFR and increased motility of cells in the absence of other cues. Edges that are bordered by agarose do not induce activation of the EGFR, indicating that activation is not due to loss of any specific type of cell–cell interaction but rather due to loss of physical constraints.     

Metabolism of thyrotropin releasing factor in two clonal cell lines of nervous system origin

Immunoreactive thyrotropin releasing factor (TRF) was detected in homogenates of two clonal cell lines, BN1010-1 and BN1010-3, derived from a rat central nervous system tumor. TRF was present in logarithmically-growing cells; daily medium changes with slightly acid culture medium (pH 6.8) greatly increased the TRF content of these cells. In contrast, TRF could not be detected in stationary phase cells. TRF peptidases were <1% as active in homogenates of BN1010 cells as those in homogenates of guinea pig brain or hypothalamus. It is expected that these cells will provide an excellent model system for the study of various aspects of TRF metabolism.     

Antibiotic as ligand. Coordinating behavior of the cephalexin towards Zn(II) and Cd(II) ions

The complex formation equilibria of Zn(II) and Cd(II) with cephalexin have been studied through potentiometric titrations. Experimental data were analyzed using the least squares computer program SUPERQUAD. The stability constants were 1g beta ZnCEX+ = 2.40, 1g beta Zn(CEX)(OH) = -4.54, 1g beta CdCEX+ = 2.18, and 1g beta Cd(CEX)(OH) = -5.18 (I = 0.1 M NaNO3), CEX complexes of formulae Zn(CEX)2(3)H2O and Cd(CEX)(OH)H2O have been synthesized and characterized by elemental analysis, IR spectra, conductivity measurements, and electronic and NMR spectra. The thermal behavior of the synthesized compounds were studied by TGA and DTA. We conclude that the metal ion interacts with the amido group of CEX.     

Cloning of an Arabidopsis thaliana gene encoding 5-enolpyruvylshikimate-3-phosphate synthase: sequence analysis and manipulation to obtain glyphosate-tolerant plants

Summary 5-enolpyruvylshikimate-3-phosphate synthase (EPSPs), the target of the herbicide glyphosate, catalyzes an essential step in the shikimate pathway common to aromatic amino acid biosynthesis. We have cloned an EPSP synthase gene from Arabidopsis thaliana by hybridization with a petunia cDNA probe. The Arabidopsis gene is highly homologous to the petunia gene within the mature enzyme but is only 23% homologous in the chloroplast transit peptide portion. The Arabidopsis gene contains seven introns in exactly the same positions as those in the petunia gene. The introns are, however, significantly smaller in the Arabidopsis gene. This reduction accounts for the significantly smaller size of the gene as compared to the petunia gene. We have fused the gene to the cauliflower mosaic virus 35 S promoter and reintroduced the chimeric gene into Arabidopsis. The resultant overproduction of EPSPs leads to glyphosate tolerance in transformed callus and plants.     

A kinetic study of the melanization pathway between L-tyrosine and dopachrome

In the pathway of melanin biosynthesis originating from L-tyrosine, the dopachrome accumulation at physiological pH is produced with a pronounced lag period, during which the level of L-dopa increases, following a sigmoidal kinetics to reach a steady-state. A kinetic model has been proposed for the overall pathway of melanization from L-tyrosine to dopachrome; it explains the lag period present during the dopachrome accumulation as well as the influence of L-tyrosine and tyrosinase over this lag period. Use of this model is also valid to explain the kinetics of L-dopa accumulation in the reaction medium, as has been tested by simulation.