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.     

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.     

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 new fixed cryosection technique for the simultaneous immunocytochemical demonstration of T6 and S100 antigens

Summary A formalin—calcium fixation method of preparing cryosections is described, which allows demonstration of Langerhans' cells by S100 antigen staining on frozen sections. The number of Langerhans' cells given by T6 antigen staining is also higher in formalin—calcium fixed frozen sections than acetone fixed frozen sections. The preparation is suitable for dual demonstration of the two antigens on the same section enabling a more accurate numerical evaluation of Langerhans' cell populations in the normal cervical epithelium.     

A new microbioassay for the measurement of lactogenic hormones in human serum

The standard Nb2 assay for biologically active prolactin has been modified to allow a rapid convenient microbioassay without loss of specificity or accuracy. Lactogenic hormones specifically stimulate the replication of Nb2 node rat lymphoma cells in suspension culture and form the basis of a currently available bioassay to measure prolactin and growth hormone in human serum. A new microbioassay was developed using microtest plates enabling a large number of samples to be assayed simultaneously whilst maintaining the overall sensitivity of the bioassay for lactogenic hormones. Growth of the Nb2 node lymphoma cells, measured by a light scattering technique using optical density on a spectrophotometer, was shown to be closely correlated with the cell number determined on a Coulter counter. Addition of excess anti-human prolactin and anti-human growth hormone completely inhibited the growth stimulatory effects of both human prolactin and human growth hormone. This new microbioassay (BA) and conventional radioimmunoassay (RIA) were used to measure lactogenic hormones in 48 normal subjects. There was a close correlation between the results of both assays for each hormone studied in the control sera. The mean basal BA/RIA ratio was 1.5 (range 0.8-2.0) for prolactin, 0.7 (range 0-4.5) for growth hormone and 1.3 (range 0.5-1.9) for total lactogenic activity.     

Quantitative comparison of Fusarium oxysporum competitiveness in relation to carbon utilization

Abstract The competitive saprophytic interaction between pathogenic and non-pathogenic strains of Fusarium oxysporum was investigated by studying their ability to competitively colonize sterilized soil. It was demonstrated that carbon was the first limiting substrate of Fusarium oxysporum growth in sterilized soil. Moreover, the efficiency with which glucose was utilized in the formation of propagules varied from one strain to another. Results of competitiion experiments showed that a linear relationship existed between the ratio of inoculum densities at the plateau (carrying capacity) and the ratio of inoculum densities incorporated into non-amended sterilized soil. The slope of the regression line indicated the competitiveness index, i.e. the competitiveness of a non-pathogenic strain in relation to that of a pathogenic strain. This parameter could be related to the yield coefficient of the strains in glucose-amended soil.