Drilomermis leioderma n. gen., n. sp. (Mermithidae:Nematoda) parasitizing Cybister fimbriolatus (Say) (Dystiscidae-Coleoptera)

The nematode Drilomermis leioderma n. gen., n. sp. (Merrnithidae) is described from larvae of Cybister fimbriolatus (Say) (Dytiscidae: Coleoptera) in Louisiana. Diagnostic characters of the genus Drilomermis are: medium-sized nematodes with the cuticle appearing smooth (lacking cross fibers) under the light microscope, six cephalic papillae, without mouth papillae, six hypodermal cords at midbody, 2 extremely long spicules (longer than 10 times body width at anus) which are separate and parallel (not twisted), an S-shaped vagina, medium-sized amphids located near head papillae, and postparasitic juvenile with a tail appendage. D. leioderma possesses a ventrally displaced mouth, very long vagina, and male genital papillae arranged in 3 double rows in the vicinity of the cloacal opening. Even when containing multiple parasites, about 40% of the hosts sulwived emergence of the memithids and lived several more days. In nature, some of these hosts may be able to continue their development, which is unusual since most mermithid-parasitized hosts die soon after the nematode emerges.     

Subcellular distribution and kinetic parameters of HS mouse liver aldehyde dehydrogenase

1. Aldehyde dehydrogenase subcellular distribution studies were performed in a heterogeneous stock (HS) of male and female mice (Mus musculus) with propionaldehyde (5 mM and 50 microM) and formaldehyde (1 mM) and NAD+ or NADP+. 2. The relative percents of distribution were: cytosolic 55-68%, mitochondrial 12-20%, microsomal 9-18% and lysosomal 3-15% for both propionaldehyde concentrations and NAD+. 3. Kinetic experiments using propionaldehyde and acetaldehyde with NAD+ revealed two separate enzymes, Enzyme I (low Km) and Enzyme II (high Km) in the cytosolic and mitochondrial fractions. 4. The kinetic data also indicated a spectrum of cytosolic low Km values that exhibited a bimodal distribution with one congruent to 40 microM and one congruent to 5 microM. 5. It was concluded that there was no significant difference in aldehyde-metabolizing capability between male and female HS mice, compared on a per gram of liver basis. The cytosolic low Km enzyme plays a major role in aldehyde oxidation at moderate to low aldehyde concentrations.     

Extracellular ATP causes Ca2(+)-dependent and -independent insulin secretion in RINm5F cells. Phospholipase C mediates Ca2+ mobilization but not Ca2+ influx and membrane depolarization

The mechanism by which extracellular ATP stimulates insulin secretion was investigated in RINm5F cells. ATP depolarized the cells as demonstrated both by using the patch-clamp technique and a fluorescent probe. The depolarization is due to closure of ATP-sensitive K+ channels as shown directly in outside-out membrane patches. ATP also raised cytosolic Ca2+ [( Ca2+]i). At the single cell level the latency of the [Ca2+]i response was inversely related to ATP concentration. The [Ca2+]i rise is due both to inositol trisphosphate mediated Ca2+ mobilization and to Ca2+ influx. The former component, as well as inositol trisphosphate generation, were inhibited by phorbol myristate acetate which uncouples agonist receptors from phospholipase C. This manoeuvre did not block Ca2+ influx or membrane depolarization. Diazoxide, which opens ATP-sensitive K+ channels, attenuated membrane depolarization and part of the Ca2+ influx stimulated by ATP. However, the main Ca2+ influx component was unaffected by L-type channel blockers, suggesting the activation of other Ca2+ conductance pathways. ATP increased the rate of insulin secretion by more than 12-fold but the effect was transient. Prolonged exposure to EGTA dissociated the [Ca2+]i rise from ATP-induced insulin secretion, since the former was abolished and the latter only decreased by about 60%. In contrast, vasopressin-evoked insulin secretion was more sensitive to Ca2+ removal than the accompanying [Ca2+]i rise. Inhibition of phospholipase C stimulation by phorbol myristate acetate abrogated vasopressin but only reduced ATP-induced insulin secretion by 34%. These results suggest that ATP stimulates insulin release by both phospholipase C dependent and distinct mechanisms. The Ca2+)-independent component of insulin secretion points to a direct triggering of exocytosis by ATP.     

The putative single-stranded DNA-binding protein of the filamentous bacteriophage, Ifl. Amino acid sequence of the protein and structure of the gene.

The protein product corresponding to the gene located in the region of the coliphage Ifl genome shown to contain the code for the single-stranded DNA (ssDNA)-binding proteins of all filamentous phages so far studied has been isolated from infected bacterial cells and its amino acid sequence determined. The mature protein contains 95 amino acids (calculated molecular mass 10553 Da). Its sequence corresponds to that predicted from the DNA sequence but lacks the initiating methionine residue. Although there is little direct sequence homology between the phage Ifl protein and the ssDNA-binding proteins of the other filamentous phages that have been studied, computer-based comparisons of various physical and structural parameters showed that the phage Ifl protein contains a domain that is closely related to domains in the coliphage T4 gene 32 protein and the Pseudomonas phage Pfl ssDNA-binding protein and suggest that the Ifl protein does have a ssDNA-binding function although we were unable to show this directly.     

The gene structure of tetranectin, a plasminogen binding protein.

The gene for human tetranectin was isolated from a genomic library with a mixture of degenerate oligonucleotide probes. The gene is about 12 kbp and contains two intervening sequences. The gene encodes a protein of 202 amino acid residues, with a signal peptide of 21 amino acid residues, followed by the tetranectin sequence of 181 amino acid residues. Northern blot analysis revealed that tetranectin mRNA was present in all eight tissues tested with the highest concentration in lung. Southern blot analysis showed hybridization to two genes. Further investigations are needed to determine whether the genes are allelic or non-allelic.