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Biochemical Genetics (v.37, #3-4)

Insulin-like Growth Factor mRNA in Barramundi (Lates calcarifer): Alternative Splicing and Nonresponsiveness to Growth Hormone by A. Kinhult Stahlbom; V. R. Sara; P. Hoeben (pp. 69-93).

Barramundi (Lates calcarifer) is ateleost of the superorder Acanthopterygii.Barramundi IGF-I cDNA was cloned and the distribution ofalternative transcripts in various barramundi tissueswas investigated using rt-PCR and RPA. It was demonstrated thatin barramundi tissues, IGF-I mRNAs were represented bytwo transcripts corresponding to the reported salmonidEa-2 and Ea-4. The acute effect of GH on hepatic IGF-I mRNA levels was investigated. Seven hoursafter intraperitonal administration of either 6 μg ofrecombinant bream GH/g body weight or saline, nosignificant increase in the levels of either of the two transcripts could be observed. The presenceof GH receptors in the barramundi liver was demonstratedin binding assays using recombinant bream GH and livermembrane preparations. An analysis of a barramundi IGF-I genomic sequence encompassing the threeexons that encode the E domain suggested that thepattern of splice site utilization is determined by thedegree of homology of the splicing signals to the consensus splice site sequences.

Keywords: TELEOST; BARRAMUNDI; INSULIN-LIKE GROWTH FACTOR I

Ethanol Tolerance and Alcohol Dehydrogenase (ADH; EC1.1.1.1) Activity in Species of the cardini Group of Drosophila by Wilma V. Colon-Parrilla; Ivette Perez-Chiesa (pp. 95-107).

Ethanol tolerance, alcohol dehydrogenase (ADH;EC1.1.1.1) activity, and tissue-specific expression wereexamined in species of the cardini group ofDrosophila using D. melanogaster as astandard of comparison. In contrast to most fruit-breeding species, allcardini species examined, two from the cardini subgroupand five from the dunni subgroup, were ethanol sensitive(LC₅₀ ≤ 2.05%) and the mean ADH activityof males ranges from only 8 to 16% that of D.melanogaster Adh^FF. Among all sevencardini species, there were small but significantdifferences in ethanol tolerance and ADH activity.Differences in enzyme mobility were in accordance with the proposedphylogeny for the dunni-subgroup species. ADH isexpressed in the fat body and midgut. Males of D.acutilabella and of D. belladunni havesignificantly less ethanol tolerance and express less ADH activitythan females in zymograms and histologicalpreparations.

Keywords: DUNNI SUBGROUP OF DROSOPHILA ; CARDINI SUBGROUP OF DROSOPHILA ; ALCOHOL; DEHYDROGENASE; ALCOHOL TOLERANCE; ADH TISSUE EXPRESSION

CAG Repeats in Various Organisms Studied by Southern Blot Analysis by Bjorn Grinde; Ingrid Olsaker; Enok Tjotta (pp. 109-117).

A 90-nucleotide (CAG)₃₀,single-stranded DNA was used to probe Southern blots inorder to indicate the quantity and distribution of longCAG repeats in selected genomes. Bovine and rat genomeswere found to contain a particularly high content of CAGrepeats, while the repeats were comparatively rare inthe human genome. A particularly strong signal in thebovine genome was due to a CAG repeat associatedwith the 1.709 satellite. A similar element wasfound in goat and musk, but not in the otherartiodactyls tested, suggesting that this particular CAGrepeat developed some 10-20 million years ago withina 3.8-kb unit presently belonging to thesatellite element and that this unit has latermultiplied in the genome. Single-copy repeats could bediscerned in yeast, but not in mammals. Thus the probedid not detect specific repeats in patients withCAG repeat diseases.

Keywords: CAG REPEATS; SOUTHERN BLOT; SATELLITES; ARTIODACTYLS; MOLECULAR EVOLUTION

The Mouse Rhl1 and Rhag Genes: Sequence, Organization, Expression, and Chromosomal Mapping by Zhi Liu; Cheng-Han Huang (pp. 119-138).

To seek an alternative model for studies of theRh protein complex, we isolated by homology cloning andcharacterized the mouse Rhced and Rhaggenes, which are homologous to the human RH andRHAG genes,respectively. Rhced encodes a glycoprotein of418 amino acids which occurs as a composite of human RhDand RhCE with 60% identity and 74% similarity. Rhagencodes a glycoprotein of 438 amino acids thatshares 79% identity and 87% similarity to humanRh50. However, Rhag has an elongated C terminus and fourN-glycosylation sites clustered on exoloop 1. Hydropathyplots suggest that Rhl1 and Rhag each spanthe lipid bilayer 12 times, with N and Ctermini facing the cytoplasm. Rhced and Rhag are bothspecified by 10 exons and bear a similar exon/intronstructure, but their major transcription start sites aremapped at –17A and –27A. Northernanalysis revealed coexpression of Rhced and Rhag from11-day embryos throughout adult life in erythroidtissues. Southern blotting and linkage analysis showedthat Rhced and Rhag are single-copygenes localized to chromosomes 4 and 17, respectively;they are paralogous to one another but orthologous tohuman RH and RHAG. The resultstogether predate the occurrence and signifya conserved function of the erythroid-specificRh membrane structures.

Keywords: MEMBRANE PROTEINS; RH HOMOLOGUES; ERYTHROCYTES; GENE STRUCTURE

Molecular Identification of a Murine Ubiquitin/60S Ribosomal Fusion Protein and Expression Study in Mouse Kidney by Lin Sun; Rudolf P. Wuthrich (pp. 139-147).

We have isolated and sequenced a 500-bp cDNAclone which is the murine homologue of a ubiquitin/60Sribosomal fusion protein. The cDNA and the deduced aminoacid sequence are highly conserved. Northernblotting demonstrates constitutive expressionin a mouse renal epithelial cell line and in mousekidneys. Upon stimulation with interferon-gamma orphorbol esters, the expression is not changed,contrastingwith the stimulation seen for polyubiquitin.Expression of the 16-kD ubiquitin/60S protein is alsodemonstrated in mouse epithelial cells.

Keywords: UBIQUITIN; FUSION GENE; RIBOSOMES; KIDNEY

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Biochemical Genetics (v.37, #3-4)

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Biochemical Genetics (v.37, #3-4)