Genetic and molecular analysis of vgU and vgW: two dominant vg alleles associated with gene fusions in Drosophila

In the absence of a vg+ gene, extensive cell death occurs in third instar imaginal discs, which results in a complete loss of adult wing margin structures. Essentially all molecularly characterized vg alleles are associated with deletions or insertions of DNA into the vg locus. These alterations reduce or eliminate a 3.8-kb vg-specific transcript, resulting in recessive loss of function alleles. We report here the analysis of two dominant vg alleles which have been identified (vgU and vgW). The vgU allele is associated with a chromosomal inversion which splits the vg locus, resulting in a gene fusion between vg and the mastermind (mam) neurogenic locus. Reversion analysis of vgU indicates that sequences from the mam locus are required for vgU dominance. The vgW allele is also the result of a chromosomal inversion, in this case resulting in a gene fusion between vg and the homeobox-containing invected (inv) gene. It is also associated with novel dominant homeotic transformations. Revertant analysis indicates that sequences from inv are required for the dominant wing and dominant homeotic effects of vgW. The vg dominance does not appear to be mediated through a reduction of vg expression or a novel fusion transcript in either vgU or vgW. The results are consistent with a model in which inappropriate expression of inv causes the dominant homeotic effects seen in vgW.

Construction of an opal suppressor by oligonucleotide-directed mutagenesis of a Saccharomyces cerevisiae tRNA(Trp) gene

In vitro mutagenesis was used to create putative opal suppressor alleles of a tRNA(Trp) gene of Saccharomyces cerevisiae. The construct with the requisite anticodon change did not result in an active suppressor, whereas when a second change was introduced into the portion of the gene encoding the intron, an active and specific opal suppressor was produced. We propose that the secondary structure of transcripts from the first mutant may prevent efficient pre-tRNA processing, whereas normal processing occurs with the double mutant.

Drosophila melanogaster tRNA(Ser) suppressor genes function with strict codon specificity when introduced into Saccharomyces cerevisiae

The anticodon of the wild-type tRNA(7Ser) gene of Drosophila melanogaster was mutated using oligodeoxyribonucleotide-directed, site-specific mutagenesis, and all three nonsense suppressor derivatives of the gene were constructed. These constructs were cloned into an Escherichia coli-yeast shuttle vector (YRp7), and used to transform a Saccharomyces cerevisiae strain [JG 369-3B(alpha)] containing an array of nonsense alleles. When tested on appropriate omission media, the D. melanogaster suppressor genes were found to function in the yeast with strict codon specificity. Subsequent Northern hybridization analyses revealed that the D. melanogaster suppressor genes were transcribed and processed well, when in S. cerevisiae.

Colony stimulating activity in the serum of patients with multiple myeloma is enhanced by interleukin 3: a possible role for interleukin 3 after high dose melphalan and autologous bone marrow transplantation for multiple myeloma

Sera from 36/37 multiple myeloma patients and 19/21 sera from patients with other solid or liquid tumours had granulocyte-macrophage colony stimulating activity (CSA) towards normal human donor bone marrow whereas 1/16 sera from normal donors had this activity. Unlike human rhGM-CSF and GM-CSF from 5637 (human bladder cell line) conditioned medium which is heat stable, CSA from serum is heat labile (56 degrees C/30 min). In multiple myeloma patients, CSA was detectable more than 2 years after treatment with 'high dose melphalan. Although multiple myeloma patients, at relapse, have sufficient CSA in their serum to produce maximal stimulation of GM-CFUc from normal donor bone marrow in vitro, their own GM population responds poorly. The results suggest that the failure of patients own bone marrow to respond to endogenous CSA may be due to damage to the stem cells of the marrow or the failure of precursor cells to respond to CSA. Addition of rhIL-3 to myelomatous serum increased the number of GM-CFUc from both normal and myelomatous bone marrow but did not stimulate the growth of MY-CFUc significantly. The results suggest that rhIL-3 may assist bone marrow recovery in multiple myeloma patients after intensive chemotherapy.

Orotidine-5'-monophosphate decarboxylase catalysis: kinetic isotope effects and the state of hybridization of a bound transition-state analogue

The enzymatic decarboxylation of orotidine 5'-monophosphate may proceed by an addition-elimination mechanism involving a covalently bound intermediate or by elimination of CO2 to generate a nitrogen ylide. In an attempt to distinguish between these two alternatives, 1-(phosphoribosyl)barbituric acid was synthesized with 13C at the 5-position. Interaction of this potential transition-state analogue inhibitor with yeast orotidine-5'-monophosphate decarboxylase resulted in a small (0.6 ppm) downfield displacement of the C-5 resonance, indicating no rehybridization of the kind that might have been expected to accompany 5,6-addition of an enzyme nucleophile. When the substrate orotidine 5'-monophosphate was synthesized with deuterium at C-5, no significant change in kcat (H/D = 0.99 +/- 0.06) or kcat/KM (H/D = 1.00 +/- 0.06) was found to result, suggesting that C-5 does not undergo significant changes in geometry before or during the step that determines the rate of the catalytic process. These results are consistent with a nitrogen ylide mechanism and offer no support for the intervention of covalently bound intermediates in the catalytic process.

Evidence that multiple myeloma may be regulated by homeostatic control mechanisms: correlation of changes in the number of clonogenic myeloma cells in vitro with clinical response

Myeloma colonies (MY-CFUc) could be grown in vitro for 6 months (median time) after a group of 12 myeloma patients had reached complete remission (CR). In a second group of 25 patients MY-CFUc increased in 17/25 and GM-CFUc in 20/25 patients after cyclophosphamide even though 24/25 patients had a partial response to VAMP and one was in CR. These data suggest that cell killing by cyclophosphamide stimulates residual tumour cells into proliferation and adds further support to the idea that myeloma is under some degree of homeostatic control which may be analogous to that in normal bone marrow. Although lymphoplasmacytoid myeloma cells may be more drug resistant than plasmacytoid myeloma cells in vitro, it was not possible to conclude that the emergence of lymphoplasmacytoid cells at relapse was indicative of resistance to further treatment.

The functional organization of the vestigial locus in Drosophila melanogaster

Vestigial mutants are associated with imaginal disc cell death which results in the deletion of adult wing and haltere structures. The vestigial locus has previously been cloned, and mutational lesions associated with a number of vg alleles were mapped within a 19 kb DNA region defined as essential for vg function. Herein we report the identification and characterization of a developmentally regulated 3.8 kb vg transcript which is spliced from exons distributed throughout the essential interval defined above. All the characterized classical alleles have predictable effects on this transcription unit, and the severity of this effect is directly proportional to the severity of the wing phenotype. A repetitive domain within this transcription unit was identified and may serve as a tag to isolate other genes with functions related to vg. We also report an exceptional vg allele (vg83b27) that produces an extreme wing and haltere phenotype, but which defines a second vg complementation unit. This allele is associated with a 4 kb deletion entirely within a 4.5 kb vg intron as defined by the 3.8 kb transcription unit. Molecular and genetic evidence indicates that the vg83b27 mutation has a functional 3.8 kb transcription unit, thus accounting for its ability to complement classical alleles. The results indicate that sequences within a vg intron are essential for normal wing and haltere development.

In vitro studies of ways to overcome resistance to VAMP--high dose melphalan in the treatment of multiple myeloma

Myeloma colonies (MY-CFUc) from 7/24 patients undergoing treatment with VAMP (vincristine, adriamycin and methyl prednisolone) and high dose melphalan (HDM) were melphalan-resistant. It was not possible to conclude that VAMP induced melphalan resistance in MY-CFUc, but that resistance is endogenous in some myeloma cell populations. In 12/13 of the same patients of whom four had MY-CFUc which were melphalan resistant, the sensitivity of MY-CFUc and GM-CFUc to busulphan was similar. Thus resistance of MY-CFUc to melphalan did not confer resistance to busulphan. MY-CFUc from 1/7 of a second group of patients were adriamycin-resistant. This resistance was removed when the cells were treated with a combination of verapamil (3 micrograms/ml) and adriamycin. Verapamil also enhanced the toxicity of adriamycin to MY-CFUc from two patients where there was no evidence for adriamycin resistance. In these three patients the sensitivity of both MY-CFUc and GM-CFUc was similar after treatment with verapamil. Verapamil did not affect the uptake or efflux of 3H-daunorubicin in sensitive and resistant RPMI-8226 cells (myeloma) and peripheral blood mononuclear cells from a normal donor; neither did it affect the binding of 3H-daunorubicin to nucleic acid. It is concluded that verapamil may be a useful adjuvant to VAMP chemotherapy and that busulphan may provide an alternative to melphalan in patients whose myeloma cells are melphalan resistant.

Increase in clonogenic tumour cells in bone marrow of patients with multiple myeloma treated with vincristine, doxorubicin, and methylprednisolone

The relation between clonogenic myeloma cells, assayed in vitro, and clinical status was studied in 20 patients with multiple myeloma before and after VAMP therapy (vincristine, doxorubicin, and methylprednisolone). 14 patients showed an improvement in clinical status, as judged by a fall in myeloma protein and a decrease in plasmacytoid myeloma cell infiltration in the bone marrow. However, in 11 of these 14, there was an increase in the number of clonogenic myeloma cells. This suggests that the treatment changed the myeloma cell population in the residual bone marrow. To be effective, subsequent chemotherapy should be aimed at destroying this population of myeloma cells.

A simple method for culturing myeloma cells from human bone marrow aspirates and peripheral blood in vitro

A double layer agar technique has been developed to grow myeloma colonies (MY-CFUc) from human bone marrow aspirates and peripheral blood. Heavily irradiated HL60 cells (5 x 10(5)/plate) are added to an agar underlay in growth medium containing 0.5% agar. Mononuclear cells from the test bone marrow or blood are overlayered in either 0.2 ml HL60-conditioned medium (HL60-CM) or in 0.5 ml growth medium containing 0.23% agar, and the cultures are incubated at 37 degrees C in an atmosphere of 5% CO2, 10% O2 and 85% N2. Colonies (greater than 50 cells) form between 2 and 3 weeks. Using this method 60/68 samples of bone marrow and 7/12 samples of blood from 54 patients have produced colonies in soft agar and in liquid on an agar underlay. The cells which form these colonies are of two distinct sizes, the larger cells being plasmacytoid and the smaller lymphoid. The two cell types are usually, but not always, present in separate colonies. Both plasmacytoid and lymphoid cells carry the isotype of the respective patient's myeloma protein and the plasma cell marker (HAN PC1). This technique has enabled us to culture myeloma cells from patients with as few as 2% plasma cells in the bone marrow but it does not permit the growth of normal B, T or granulocyte-macrophage colonies (GM-CFUc). The drug sensitivity of myeloma cells (MY-CFUc) compared with normal haemopoietic cells (GM-CFUc) can be measured using dose-response curves in individual patients. Furthermore, this method can detect resistant subpopulations within a given myeloma sample.

Molecular organization of the vestigial region in Drosophila melanogaster

The vestigial (vg) locus of Drosophila melanogaster is involved in wing margin development. In the absence of a vg+ gene, extensive cell death occurs in third instar imaginal discs which results in a complete loss of adult wing margin structures. P-element tagging was used to obtain a molecular clone of the vg locus, which led to the molecular characterization of approximately 46 kb of DNA from the region. Deficiency analysis and molecular mapping identified sequences, spanning approximately 20 kb of DNA within the larger region, which are necessary for vg function. The molecular map was oriented with respect to a pre-existing genetic fine structure map of the locus. The centromere distal limits of the locus were defined by deficiency analyses while the proximal end has not yet been conclusively established. However, three transcripts, that are apparently unrelated to vg, provide circumstantial evidence for the proximal limits of the vg locus. The nature of the molecular lesions for several extant recessive or lethal vg alleles was determined, and these were placed on the vg molecular map. The characterization of the lesions associated with two dominant vg alleles and one complex vg allele imply interesting regulatory mechanisms for this locus. As well, a revertant of a 412 insertion mutant allele was shown to have resulted from a further insertion of a roo element into the 412 element.

Transformation of Drosophila melanogaster with a suppressor tRNA gene (Sup3e tRNA(SerUGA)) from Schizosaccharomyces pombe

P-element mediated transformation was utilized to introduce a suppressor tRNA gene (Sup3e tRNA(UGASER)) from Schizosaccharomyces pombe into Drosophila melanogaster. Thirteen independently transformed lines were characterized as to the number of cytological locations of the transposons. It was ascertained that the suppressor tRNA gene of interest was introduced into each transformed strain. The helper P element used (p pi 25.1) allows further transposition to occur, and it was determined that from one to seven copies of the heterologous tRNA(UGASER) gene per strain were present among the respective transformed strains. The number of transposons per transformed line was established by in situ hybridization to salivary gland chromosomes as well as by Southern hybridization analyses and there was good agreement in the totals determined by these two techniques.

Molecular analysis of hybrid dysgenesis-induced derivatives of a P-element allele at the vg locus

Secondary and tertiary derivatives of a P-element insertion allele at the vestigial (vg) locus were induced by hybrid dysgenesis. The derivatives were characterized by Southern analyses and, in four cases, by DNA sequencing. The alterations found were P-element internal deletions, deletions of the insert and/or adjacent vg region DNA, or novel insertions of P-element sequences into existing P-element inserts. The relatively high frequency of secondary insertions into P-element sequences observed herein is unusual, since secondary insertions have seldom been recovered in other dysgenic screens. The effects of the alleles on vg expression were determined. The results are consistent with a model in which the insertions disrupt vg gene expression by transcriptional interference.

Activation of murine 'T' lymphomas in the presence of a human myeloma cell line, RPMI-8226, in vivo

Images

A chronic lung disorder following abdominal pregnancy

Abdominal pregnancy is a rare condition that is associated with a high infant mortality, as well as orthopedic and pulmonary deformations. This article describes the clinical and radiological courses of two infants born after abdominal pregnancies. Evidence of pulmonary hypoplasia secondary to fetal compression was present. The morbidity and mortality for infants born of abdominal pregnancies may depend on the extent of pulmonary involvement, which may relate to the length of fetal compression.

Comparison of melphalan toxicity in human lymphocytic cells and Chinese hamster cells in vitro: the relationship between DNA-DNA cross-link formation and clonogenic survival

Human CCRF-CEM ('T' cell), EB3p ('B' cell) and RPMI-8226 (myeloma cell) lymphocytic cell lines were an order of magnitude more sensitive to melphalan (MEL) than Chinese hamster, V-79-753B, cells even though the amount of [14C]MEL they incorporated was less than 50% of that incorporated into the rodent cells: the D0 values were 0.16, 0.20 and 0.30 microgram/ml respectively compared with 1.6 micrograms/ml. Furthermore, MEL sensitivity was not related to the total thiol content of the cells. DNA-DNA cross-linking was not detectable in lymphocytic cells using the alkaline elution technique at doses of MEL used for clonogenic survival, whereas in Chinese hamster cells both parameters were assessable within the same dose range. At high concentrations of MEL there was a direct relationship between DNA-DNA cross-linking and drug dose in each lymphocytic cell line. Changes in the amounts of DNA-DNA cross-linking, at different MEL concentrations, increased directly with the sensitivity of the cells, viz. CCRF-CEM greater than EB3p greater than RPMI-8226. Calculated survival values for doses of MEL which produced measurable DNA-DNA cross-linking showed that there was a similar relationship between these parameters for the three lymphocytic cell lines which was different from that for Chinese hamster cells. It is concluded that the contribution of DNA-DNA cross-links in determining cell survival after MEL treatment is both quantitatively and possibly qualitatively different in human and rodent cells and that DNA-DNA cross-linking cannot be used as an indicator of MEL sensitivity in human lymphocytic cells unless parallel clonogenic survival studies are also undertaken.

Lymphotoxic activity of methyl prednisolone in vitro--I. Comparative toxicity of methyl prednisolone in human cell lines of B and T origin

The cytotoxic activity of methyl prednisolone was compared in EB-3(B), NALM-6(B), CCRF-CEM(T) and RPMI-8226 (plasma cell) cell lines derived from human lymphoid malignancies. Whereas EB-3 cells were steroid-sensitive, NALM-6 cells were partially sensitive and CCRF-CEM and RPMI-8226 were steroid resistant at concentrations of methyl prednisolone up to 10(-4) M. A high concentration of methyl prednisolone, 2.5 X 10(-3) M was toxic to all cell lines. Steroid-sensitivity did not correlate with the incorporation of [3H] dexamethasone and could not be mimicked by flurbiprofen, a non-steroidal anti-inflammatory agent. Both theophylline and di-butyryl cAMP were toxic towards NALM-6, EB-3 and CCRF-CEM cells; however, this toxicity was reversible and did not reflect the cells' sensitivities towards methyl prednisolone. Furthermore, elevated levels of cAMP in theophylline-treated cells, were not demonstrable in cells treated with methyl prednisolone at toxic or non-toxic concentrations of the steroid. Steroid-sensitive EB-3 cells exposed to 10(-5) M methyl prednisolone, produced a soluble factor which was toxic CCRF-CEM cells.

Effects of alpha-melanocyte-stimulating hormone on the cyclic AMP and phospholipid metabolism of rat adrenocortical cells

Results on the effects of peptides on the phospholipid metabolism and steroid and cyclic AMP (cAMP) outputs of rat adrenal capsular cells (96% zona glomerulosa, 4% zona fasciculata) were obtained in a series of three batch experiments. Their significance was examined by analysis of variance. Incorporation of [32P] into phosphatidylcholine, phosphatidic acid and phosphatidylinositol was measured. Production of [3H]inositol-1 monophosphate, inositol-1,4 bisphosphate and inositol-1,4,5 tris-phosphate was estimated after prelabelling with [3H]inositol followed by 1 min incubation with a steroidogenic stimulus. Angiotensin II (0.25 nmol/l to 0.25 mumol/l) highly significantly (P less than 0.01) stimulated aldosterone and corticosterone outputs, [32P] incorporation into phosphatidic acid and phosphatidylinositol (but not into phosphatidylcholine) and the production of the three [3H]inositol phosphates. Aldosterone and corticosterone outputs were stimulated by alpha-MSH (above 0.1 nmol/l). However, incorporation of [32P] was not significantly increased until 10 mumol alpha-MSH/l but, unlike with angiotensin II, incorporation into phosphatidylcholine was also then stimulated. Also, the production of the inositol phosphates was not increased significantly (P greater than 0.05) by any dose of alpha-MSH (10 nmol/l, 1 mumol/l and 0.1 mmol/l) used. Therefore, it can be concluded that alpha-MSH does not stimulate phospholipase C in rat zona glomerulosa cells. In further experiments, it was also found that there were significant increases in cAMP as well as in steroid outputs above 1 nmol alpha MSH/l (highly significant above 10 nmol alpha-MSH/l). There were plateaux of the outputs of both steroids and cAMP from 0.1 to 1 mumol alpha-MSH/l. However, there were further increases in steroid and cAMP outputs of the capsular cells at higher doses. Concomitant results on the stimulation of corticosterone output by zona fasciculata-reticularis cells indicate that this additional increase was mostly due to the stimulation of the contaminating zona fasciculata cells. It was also confirmed that alpha-MSH preferentially stimulates steroidogenesis by the zona glomerulosa. However, under our conditions, alpha-MSH highly significantly increased the output of cAMP by both zona fasciculata and glomerulosa cells.

The effects of ACTH, serotonin, K+ and angiotensin analogues on 32P incorporation into phospholipids of the rat adrenal cortex: basis for an assay method using zona glomerulosa cells

The effects of various concentrations of serotonin, ACTH, K+, angiotensin II (AII), angiotensin III (AIII) and [Sar1]angiotensin II (SAII) on steroidogenesis and the incorporation of 32P (after preincubation to near equilibrium with the ATP pool) into phosphatidylinositol (PI), phosphatidic acid (PA) and phosphatidylcholine (PC) in a preparation of capsular cells from rat adrenals, consisting of 95% zona glomerulosa (z.g.) and 5% zona fasciculata plus reticularis (z.f.r.) cells, were investigated. Serotonin and ACTH stimulated steroidogenesis in the usual manner but had little or no effect on 32P incorporation into any of the three phospholipids. However, AII, AIII and SAII stimulated steroidogenesis and also 32P incorporation into PA and PI (maximally to about 280% of control values) but not into PC. These results taken together with other data on effects on the cAMP output and Ca2+ fluxes of z.g. cells suggest that stimulation by ACTH and serotonin is mediated by cAMP as second messenger. However, the angiotensins probably act through Ca2+, with associated changes in phospholipid metabolism. The 32P incorporation into PA as a function of lg concentration of AII was linear and showed a reasonable index of precision (0.36 +/- 0.03, eight experiments, 0.23 +/- 0.02 for a further eight experiments) and correlation with steroidogenesis. The corresponding incorporation into PI showed a maximum effect and a much poorer index of precision (1.02 +/- 0.30 (4.69 +/- 3.7] over the same full range of AII concentration used. The effects of AIII and SAII showed similar characteristics for 32P incorporation into both PA and PI, but, as for stimulation of steroidogenesis, at higher concentrations for AIII than for AII. The effects of different doses of AII, AIII and ACTH on the corticosterone output and 32P incorporation into PA, PI and PC of a preparation of cells, consisting of more than 98% z.f.r. cells, from rat decapsulated adrenals were also studied. ACTH, at low doses, which nevertheless markedly stimulated corticosterone output, had a small (maximally to about 125% of control values) but significant effect on 32P incorporation into PA, PI and PC. The maximum effect was usually at about 10(-10) M ACTH and was not significant at 10(-8) M.

The DNA sequence and genetic organization of a Neurospora mitochondrial plasmid suggest a relationship to introns and mobile elements

We have determined the complete 3581 bp sequence of the mitochondrial plasmid from Neurospora crassa strain Mauriceville-1c. The plasmid contains a long open reading frame that is expressed in its major transcript and could encode a hydrophilic protein of 710 amino acids. Two characteristics of the plasmid--codon usage and the presence of conserved sequence elements--suggest that it is related to Group I mtDNA introns. The major transcripts of the plasmid are approximately full-length, colinear RNAs that have heterogenous 5' ends and a single major 3' end. The major 5' and 3' ends are adjacent and slightly overlapping. The Mauriceville plasmid may belong to a class of genetic elements that were or are the progenitors of mtDNA introns.

The use of the superfusion approach with rat adrenal capsular cells to compare the steroidogenic potencies of angiotensin analogues, without the effects of peptide degradation

The superfusion approach was used to assay the relative potencies of (Asp1)angiotensin II (A II), (des-Asp1)angiotensin II (A III) and (Sar1)angiotensin II (SA II) in stimulating the steroidogenesis (corticosterone) of rat adrenal capsular (zona glomerulosa) cells without the effects of peptide degradation; an example of the advantages of such a procedure. At the rate of superfusion employed, there was no significant reduction in the concentration of A II or A III through the cell chamber. However, in the in vitro closed system A III was degraded more rapidly than A II. SA II would be expected to be more protected than A II. The potency ratios were found to be 0.30 +/- 0.05 (s.e.), four experiments for A III/A II and 2.23 +/- 0.16 (s.e.), six experiments for SA II/A II in the usual closed system with 1 h incubations. In the superfused system, however, the corresponding ratios were 0.82 +/- 0.11, five experiments and 1.19 +/- 0.23, four experiments. These results indicated that, as shown by the relative potencies in the superfusion system and therefore without the effects of degradation. A II, A III and SA II have about the same intrinsic activity. The reason for the relatively high activity of SA II in the closed system is its lower rate of degradation compared with A II and the low activity of A III is owing to its relatively high rate of degradation. It is concluded that, although the intrinsic activities of A III and A II are similar, because of the equivalent activity of SA II, it is probably not necessary for SA II, or therefore also A II, to be converted to A III for it to stimulate steroidogenesis in the system.