Alkaline phosphatase isozymes as possible markers of differentiation in human testicular teratocarcinoma cell lines

The alkaline phosphatase (ALP) activity in eight independent cell lines derived from human testicular germ cell tumors was characterized. Seven out of eight of the lines had high ALP levels, and most of the activity in each case was of the liver/bone/kidney ALP type, as judged by thermostability, inhibition, and electrophoretic studies. Low levels of a heat stable, placental-like ALP were also present in these seven lines; only a small subpopulation of the cells of each line reacted strongly with an anti-placental ALP monoclonal antibody. The heat-stable, placental-like isozyme characteristic of these lines differed from the normal placental ALP in its inhibition profile. Thus it is possible that a subpopulation of the cells in these lines expresses a new embryonic ALP form.     

Complex binding interactions between multicomponent mixtures and odorant receptors in the olfactory organ of the Caribbean spiny lobster Panulirus argus

Our study was designed to examine how components of complex mixtures can inhibit the binding of other components to receptor sites in the olfactory system of the spiny lobster Panulirus argus. Biochemical binding assays were used to study how two- to six-component mixtures inhibit binding of the radiolabeled odorants taurine, L-glutamate and adenosine-5'-monophosphate to a tissue fraction rich in dendritic membrane of olfactory receptor neurons. Our results indicate that binding inhibition by mixtures can be large and is dependent on the nature of the odorant ligand and on the concentration and composition of the mixture. The binding inhibition by mixtures of structurally related components was generally predicted using a competitive binding model and binding inhibition data for the individual components. This was not the case for binding inhibition by most mixtures of structurally unrelated odorants. The binding inhibition for these mixtures was generally smaller than that for one or more of their components, indicating that complex binding interactions between components can reduce their ability to inhibit binding. The magnitude of binding inhibition was influenced more by the mixture's precise composition than by the number of components in it, since mixtures with few components were sometimes more inhibitory than mixtures with more components. These findings raise the possibility that complex binding interactions between components of a mixture and their receptors may shape the output of olfactory receptor neurons to complex mixtures.      

A method for generating hybrids containing nonselected fragments of human chromosomes

We have used an irradiation and fusion technique to generate somatic cell hybrids that contain human chromosomal fragments. As a model system, a human-hamster hybrid containing a single human X chromosome was gamma-irradiated and fused with a rodent line. Hybrids were obtained without imposing direct selection for human material. Analysis of 29 clones by in situ hybridization and Southern blotting revealed that human fragments were incorporated into the hybrid cell genomes in most lines. Like chromosome-mediated gene transfer (CMGT)-generated hybrids, these hybrids contained multiple human fragments and retained alphoid centromeric sequences with a high frequency. However, unlike the CMGT, human fragments (apart from alphoid sequences) of less than 10(7) bp showed no evidence for rearrangements. This technique provides a method for constructing hybrids that contain a limited number of small human fragments derived exclusively from any chromosome of choice without the need to impose selection. Such hybrids provide a valuable resource for high-resolution mapping over short distances and for the isolation of disease and other loci mapped genetically.     

Evaluating the forced oscillation technique in the detection of early smoking-induced respiratory changes

Background  

Early detection of the effects of smoking is of the utmost importance in the prevention of chronic obstructive pulmonary disease (COPD). The forced oscillation technique (FOT) is easy to perform since it requires only tidal breathing and offers a detailed approach to investigate the mechanical properties of the respiratory system. The FOT was recently suggested as an attractive alternative for diagnosing initial obstruction in COPD, which may be helpful in detecting COPD in its initial phases. Thus, the purpose of this study was twofold: (1) to evaluate the ability of FOT to detect early smoking-induced respiratory alterations; and (2) to compare the sensitivity of FOT with spirometry in a sample of low tobacco-dose subjects.     

Members of the human glyceraldehyde-3-phosphate dehydrogenase-related gene family map to dispersed chromosomal locations

Several highly homologous glyceraldehyde-3-phosphate dehydrogenase (GAPD)-related sequences have been identified previously in human DNA by Southern blot analysis. Protein studies have identified only a single expressed locus for this major glycolytic enzyme, and this maps to chromosome 12p13. Sequence analysis of a GAPD muscle cDNA clone and a GAPD-related clone retrieved from an X-chromosome recombinant library showed that the latter was a processed pseudogene that maps to Xp11-p21. In this study, we have determined the chromosomal locations of several of the additional GAPD-related human sequences using a short 3' end sequence from the cDNA to probe DNA from a series of human-rodent somatic cell hybrids on Southern blots. Eight HindIII GAPD-related sequences detected at high stringency have been mapped to 6 different chromosomes. Several of the additional sequences detected at more moderate stringency have been localized to a further 10 chromosomal sites. Together, these sites constitute the known expressed locus, the known X-linked pseudogene, and 15 GAPD-like loci.     

The ultrastructure of microorganisms in the tissues of Casinaria infesta (Hymenoptera:Ichneumonidae)

Two types of microorganisms were observed in the tissues of Casinaria infesta. Type I was a typical rickettsialike microorganism which occurred in digestive, reproductive, nerous, respiratory, and connective tissue. This microoganism appeared to undergo changes within the cells of the calyx resulting in a uniformly dense coccoid organism. The Type II microorganisms were observed in the cytoplasm, nucleus, and lumen of the calyx, and within the lumen of the oviduct. This microorganism was small, rod-shaped, and had a bled or protrusion at one or both ends. Type II microorganisms appear to form de novo in the nucleus of the calyx cells and to replicate by fission or budding. The nature of the Type II microorganism is unresolved.