Hb A2-Wrens or alpha 2 delta 2 98(FG5) Val----Met, an unstable delta chain variant identified by sequence analysis of amplified DNA

Data are reported for an 85-year-old black make who had an HPFH condition on one chromosome and a suspected 'delta-thalassemia' on the other. Sequence analysis of amplified DNA of an appropriate segment of the delta-globin gene identified a GTG to ATG mutation for codon 98 and thus a Val----Met replacement in the delta chain. This abnormality was confirmed by hybridization of amplified DNA with 32P-labeled synthetic probes and by the amino-acid composition of the isolated tryptic peptide delta T-11. Thus, the 'delta-thalassemia' is caused by the presence of an Hb A2 variant that is considered to be unstable to a similar extent as is Hb K?ln, its beta chain counterpart.     

Echinococcus granulosus: ultrastructure of epithelial changes during the first 8 days of metacestode development in vitro

The epithelium of artificially hatched and activated oncospheres of E. granulosus was studied ultrastructurally over the first 8 days of metacestode development in vitro. Within 4 h of activation, the epithelium was transformed from a thin cytoplasmic layer into a much wider layer packed with penetration gland granules and containing mitochondria and Golgi apparatus. Microvilli were extended from the outer plasma membrane and the basal lamina on the inner epithelial surface virtually disappeared. Microvilli increased in number and length over the first 24 h of development while granules in both the epithelium and penetration gland decreased in number. The granules appear to be involved in microvilli formation. After 3 days of development, the first lamination resolved ultrastructurally as shortened microvilli and some microtriches extending from the epithelium surrounded by an electron-dense microfibrillate material containing sloughed microvilli. By 6 days post-activation, no microvilli remained and only double-walled truncated microtriches extended from the epithelium. The microfibrillate material had become more electron-dense and was closer to the epithelium than at day 1. Within 8 days of metacestode development, a second lamination had developed. Both microfibrillate and particulate material of a greater electron density than the first lamination was added to the microthrix side of the first lamination.     

Disruption of pattern formation in palatal rugae in fetal mice heterozygous for First arch (Far)

The purpose of this study was to document the extent of disruption in the pattern of palatal rugae caused by the presence of one copy of the First arch mutation. The palatal ruga pattern was found to be disrupted in 86% of 15- to 17-day mouse fetuses that were heterozygous for the First arch mutation in the ICR/Bc strain, compared with 9% in ICR/Bc fetuses of normal (+/+) genotype. This new observation in First arch heterozygotes, together with the previously reported dominant effects of the First arch mutation, particularly the bifurcation of the maxillary nerve (100% in both BALB/cGaBc and ICR/Bc strains), the disruption of maxillary vibrissa pattern (80% in ICR/Bc), and the hemifacial deficiency (38% in ICR/Bc), has led us to redefine the First arch mutation as a semidominant, Far. Like the other defects caused by Far, the rugal defects are in tissue derived from the embryonic maxillary prominence. The rugal defects observed in +/Far palates were always asymmetrical and most often involved fragmentation and misalignment of two or more of rugae 4-7. The relatively large degree of variation in ruga pattern observed in fetuses of normal genotype suggests that it is a less well canalized trait than the normal pattern of maxillary vibrissae which varies only in a few very specific and minor ways. The First arch mutation, which in heterozygotes disrupts pattern formation in both palatal rugae and maxillary vibrissae, can be used to study genetic control of pattern formation in mammalian embryos.     

Physiological adaptations of an under-ice population of Pseudocalanus in Barrow Strait (N.W.T) to increasing food supply in spring

Summary Zooplankton and water samples were collected at weekly intervals between April 25 and May 30, 1986 in Barrow Strait, N.W.T. (Canadian Arctic Archipelago). In tows from 0–30 m, the zooplankton community (>202 m) was dominated by Pseudocalanus. The population was apparently growing and developing as shown by an increase in the proportion of adults (stage VI) and decreases in the proportion of stages III, IV, and V as the season progressed. Respiration and excretion rates of the Pseudocalanus populations were probably linked, there being an immediate increase in excretion rate, accompanying an increase in feeding rate when chlorophyll concentrations increased, which was followed by a smaller increase in respiration rate after a time lag. Hence, there was a large decrease in the ON ratio. Increased metabolism coincided with changes in the population structure, as did protease and bodily protein, but could not be clearly linked to dietary acclimation. Only laminarinase activity could be statistically related to an identifiable fraction of potential nutritional value in the water, particulate soluble carbohydrate, but neither showed overall seasonal change.     

The precursor of a metalloendopeptidase from human rheumatoid synovial fibroblasts. Purification and mechanisms of activation by endopeptidases and 4-aminophenylmercuric acetate.

Two active forms (Mr 45,000 and 28,000) of a metalloendopeptidase that digest proteoglycans and other extracellular matrix components of connective tissues have previously been purified from rheumatoid synovial cells and characterized [Okada, Nagase & Harris (1986) J. Biol. Chem. 261, 14245-14255]. To study the mechanisms of activation the precursor of this metalloendopeptidase has now been purified. The final products are homogeneous on SDS/polyacrylamide-gel electrophoresis and identified as a set of zymogens of Mr 57,000 and 59,000, in which the latter form is probably the product of post-translational glycosylation of the Mr 57,000 zymogen, as it binds to concanavalin A. The zymogen can be activated by trypsin, chymotrypsin, plasma kallikrein, plasmin and thermolysin, but not by thrombin. Although the activated metalloendopeptidase is further degraded by trypsin, plasma kallikrein and thermolysin during a prolonged incubation, it is relatively stable against plasmin and chymotrypsin. Activation with 4-aminophenylmercuric acetate is dependent on its concentration. It requires the reaction with the zymogen, possibly through thiol groups, and the continued presence of the agent. During this treatment the zymogen undergoes a sequential processing; first it becomes active without changing its apparent molecular mass, and then it is processed to low-Mr species of Mr 46,000, 45,000 (HMM) and 28,000 (LMM). The rate of conversion of the precursor into an initial intermediate of Mr 46,000 follows first-order kinetics (t1/2 2.0 h with 1.5 mM-4-amino-phenylmercuric acetate at 37 degrees C) and is independent of the initial concentration of the zymogen or the presence of up to a 676-fold molar excess of substrate, whereas the generation of HMM and LMM species is affected by these parameters. These results indicate that activation of the prometalloendopeptidase by an organomercurial compound is initiated by the molecular perturbation of the zymogen that results in conversion into the 46,000-Mr intermediate by an intramolecular action; the subsequent processing of this intermediate in HMM and LMM species is a bimolecular reaction. In vivo it is probable that the precursor of this metalloendopeptidase is activated either by direct limited proteolysis by tissue or plasma endopeptidases, or, alternatively, by factors that cause certain conformational changes in the zymogen molecule.     

Sequence identity between an inverted repeat family of transposable elements in Drosophila and Caenorhabditis.

The Tc1-like transposable elements, originally described in Caenorhabditis elegans, have a much wider phylogenetic distribution than previously thought. In this paper, we demonstrate that Tc1 shares sequence identity in its open reading frame and terminal repeats with a new transposable element Barney (also known as TCb1-Transposon Caenorhabditis briggsae 1). Barney was detected and isolated by Tc1 hybridization from the closely related nematode species, Caenorhabditis briggsae. The conserved open reading frames of Tc1 and Barney share identity with a structurally similar family of elements named HB found in Drosophila melanogaster, after the introduction of 3 small centrally located deletions in HB1. These reading frames would code for proteins with 30% amino acid identity (42% when conservative changes are included). Tc1, Barney and HB1 contain highly conserved blocks of amino acids which are likely to be in the functional domains of the putative transposase.     

Cystic fibrosis typing with DNA probes: experience of a screening laboratory

Summary A sample of 125 individuals from 37 British cystic fibrosis (CF) families with at least one living affected child were typed with probes for restriction fragment length polymorphisms (RFLPs) known to be linked to the CF gene. These probes were MetD, MetH, pJ3.11 and 7C22. Using this combination of probes, 30 out of the 37 families were sufficiently informative to enable prenatal diagnosis of the disease. Linkage analysis has also proved to be useful in excluding CF in two cases where diagnosis of the disease was equivocal in the sibling of an affected child.     

Effect of culture media and growth phase on the morphology of lactobacilli and on their ability to adhere to epithelial cells

Previous studies have demonstrated that the ability of lactobacilli to attach to and colonize uroepithelial surfaces is an important characteristic that enhances interference against uropathogenic bacteria. This adherence capacity was found to vary amongst lactobacillus strains and with the type of growth medium used to culture the organisms. The present study was undertaken to examine further the effect of culture media and growth phase on lactobacillus adherence to uroepithelial cells in vitro. In addition, a freeze substitution technique was developed to examine the morphology of strainsLactobacillus casei ssrhamnosus RC-17,L. casei GR-1, andL. acidophilus T-13 in relation to growth conditions and adhesion. A growth curve was plotted for strain GR-1, and adherence was found to be lowest for bacteria in early log phase (39 bacteria per uroepithelial cell) and highest in stationary phase (59 bacteria per uroepithelial cell). Strains RC-17 and GR-1 attached in high numbers to uroepithelial cells, whereas T-13 was poorly adherent. The latter formed a long, relatively dense, fibrous capsule after growth in brain heart infusion yeast extract agar, unlike strains GR-1 and RC-17, which formed a short, tightly bound, electron-dense capsule which surrounded the cells in a radial fashion. Growth of RC-17 in batch cultures of human urine, with and without addition of carbohydrates, resulted in formation of an irregular, fibrous extracellular matrix. These experiments illustrate that growth phase and culture conditions affect the extracellular structure of lactobacilli and also affect the adherence capacity of these bacteria. Structural changes mediated by availability of nutrients may partly explain why lactobacilli vary between species and between hosts in their colonization of the urogenital tract.     

Synthesis of eicosanoids by gamma-interferon-differentiated U937 cells

Interferons induce morphological, biochemical and functional alterations in monocyte macrophage and myeloid cell lines. We studied the effect of 3 days incubation with gamma-interferon from human buffy coats on the global synthesis of arachidonic acid metabolites by U937 cells. Interferon-induced morphologic changes including cytoplasmic and nuclear changes and the appearance of multiple lysosomal-like granules consistent with cellular differentiation were observed by electron microscopy. The labeling of phosphatidylserine, phosphatidylcholine and phosphatidylethanolamine was increased and that of phosphatidylinositol, free fatty acids as 3H-arachidonic acid and neutral lipids reduced, when interferon-treated cells were incubated with 3H-arachidonic acid. Interferon caused qualitative and quantitative changes in the synthesis of cyclooxygenase and lipoxygenase products. A23187, a calcium ionophore, and the tumor promotor, phorbol myristate acetate, greatly increased the synthesis by interferon-differentiated cells of 2 cyclooxygenase products; synthesis of lipoxygenase products was reduced. In the presence of indomethacin, 'shunting' into putative lipoxygenase products occurred. The relationship between interferon-induced morphologic and functional changes, the development of altered phospholipid and eicosanoid metabolism and the identity of these metabolites are yet to be established.