Characterization of acid phosphatase-1 null activity mutants of Drosophila melanogaster

Molecular characterization of the lysosomal acid phosphatase from Drosophila melanogaster

In Drosophila, unlike humans, the lysosomal acid phosphatase (Acph-1) is a non-essential enzyme. It is also one of the most rapidly evolving gene-enzyme systems in the genus. In order to determine which parts of the enzyme are conserved and which parts are apparently under little functional constraint, we cloned the gene from Drosophila melanogaster via a chromosomal walk. Fragments from the gene were used to recover an apparently full-length cDNA. The cDNA was sub-cloned into a Drosophila transformation vector where it was under the control of the 5' promoter sequence of the hsp-70 gene. Three independent transformants were obtained; in each, Acph-1 expression from the cDNA was constitutive and not dependent on heat shock, as determined by densitometric analyses of the allozymic forms of the enzyme. The pattern of expression indicates the hsp-70 and endogenous Acph-1 promoters act together in some, but not all, tissues. The sequence of the cDNA was determined using deletions made with exonuclease III, and primers deduced from the cDNA sequence were used to sequence the genomic clone. Five introns were found, and putative 5' upstream regulatory sequences were identified. Amino acid sequence comparisons have revealed several highly conserved motifs between Drosophila Acph-1 and vertebrate lysosomal and prostatic acid phosphatases.

The isolation of the acid phosphatase-1 gene of Drosophila melanogaster and a chromosomal breakpoint inducing its position effect variegation

Over 120 kb of contiguous genomic DNA sequence derived from the 99C-99D region of the Drosophila melanogaster third chromosome were isolated by molecular cloning. Sequences within this region required for the expression of the lysosomal gene-enzyme system acid phosphatase-1 (Acph-1) were identified by both P element-mediated germline transformation and transient expression and lie within a single 5 kb fragment. Acph-1 is encoded by a 2.1 kb poly(A)+ RNA transcript, which is expressed throughout development. Enzyme activity peaks also correlate with increases in RNA abundance. The ca-74 deletion, which exhibits position effect variegation at the Acph-1 gene (Frisardi and MacIntyre 1984), was also partially characterized. The variegating ca-74 breakpoint is located approximately 20 kb proximal to the Acph-1 gene. Results suggest that the heterochromatin at this breakpoint comprises highly repetitive or satellite DNA.

Comparison of the property of a novel isozyme E (formerly null mutant, O) with other isozymes of hemolymph acid phosphatase of the silkworm

1. A novel acid phosphatase isozyme E (formerly null mutant 0) was partially purified by ammonium sulfate fractionation, DEAE-Sephacel and Sephacryl S-200 column chromatography, and its properties were compared with those of other isozymes of the silkworm hemolymph. 2. The isozyme E was extremely heat labile and showed lower pH-stability than those of others. 3. Three isozymes hydrolyzed p-nitrophenyl phosphate, alpha-naphthyl phosphate, alpha-naphthyl phosphate and glucose-1-phosphate strongly. The isozyme E showed about 50% hydrolyzing activity for alpha-naphthyl phosphate as compared to those of A and B. 4. Activities of three isozymes were inhibited by tartaric acid, sodium fluoride, ammonium molybdate and potassium diphosphate. Inhibitory effects of Cu(2+) and HG(2+) were most remarkable against E isozyme.

Naturally occurring quantitative variants of acid phosphatase-1 in Drosophila melanogaster

We have examined 111 wild Drosophila melanogaster lines for cis-acting quantitative variants of the Acph-1 gene, which codes for acid phosphatase-1 (ACPH). Three variants with obvious, reproducible phenotypes were isolated. All variants acted equally on all tissues and developmental stages examined. No recombinants were detected between one quantitative variant and the site determining the electrophoretic mobility of Acph-1 among 3885 flies examined. Several enzymatic properties of the variant enzymes were tested, including the Km values for two substrates, inhibition by three different inhibitors, and thermal stability; the variant enzymes behaved identically to the wild-type enzyme in all cases. Immunological titration experiments showed that the variant enzymes had the same enzyme activity per molecule of ACPH as the wild-type enzyme. These results suggest that the quantitative variants we have identified are altered in the regulatory portion of Acph-1 so as to produce altered numbers of normal ACPH molecules.

Position effect variegation of an acid phosphatase gene in Drosophila melanogaster

X-ray mutagenesis has produced a series of deficiencies in a duplication of part of the third chromosome containing the acid phosphatase gene (Acph-1) in Drosophila melanogaster. In one of these deficiencies, Acph-1 is shown to be undergoing position effect variegation. Naturally occurring electrophoretic variants of the enzyme were used to visualize and determine quantitatively the extent of variegation of the allele which is cis to the heterochromatic breakpoint. Alteration of genotypic background and temperature provided further evidence for position effect. Rocket immunoelectrophoresis was used to correlate the levels of acid phosphatase activity and protein in flies containing the deficiency. A novel result indicates that the variegation is not the consequence of an averaging of active and inactive cells, but rather due to a quantitative alteration of gene activity within at least some individual cells.

Cell degeneration in the developing optic lobes of the sine oculis and small-optic-lobes mutants of Drosophila melanogaster

In the small-optic-lobes (sol) and sine oculis (so) mutants of Drosophila melanogaster extensive cell death occurs in the optic lobes during the first half of pupal development. Gynandromorph flies show that the sol mutation acts primarily on cells of the medulla cortex. Degeneration of medullar ganglion cells occurs at an early stage of cellular differentiation, when their axons have not yet participated in the formation of the second optic chiasma. The so gene, on the other hand, acts on the eye anlagen. The analysis of chimeric flies demonstrates that degeneration in the optic lobes of so flies is a consequence of eye reduction. At the level of the second optic chiasma extensive axonal degeneration can be observed in the mutant. Neurons seem to die after their failure to establish a sufficient number of functional contacts. In sol;so double mutants, the mutational effects are cumulative causing complete degeneration of columnar cell types in pupae without any eye anlage. The tiny rudiments of the optic lobes in eyeless double mutants still contain tangential neurons of the medulla and of the lobula complex. The central brain is reduced in size due to the missing visual fibers, however, its overall appearance is surprisingly normal.

Evolution of acid phosphatase-1 in the genus Drosophilia. Immunological studies

The enzyme acid phosphatase-1 was partially purified from 10 Drosophila species. Four antisera were produced and the ten enzymes were reacted against each serum. The method used to quantitate the reactions involved the electrophoretic separation of antigen-antibody complexes from uncomplexed enzyme, followed by densitometry of the free enzyme. Immunological distances were used to obtain correlation coefficients for all pairwise combinations of the 10 species. From these correlation coefficients, a dendrogram was constructed which is very similar to one diagramming the presumed phylogenetic relationships of the ten species. In addition, the data indicate acid phosphatase-1 has evolved at different rates in different lineages within the genus. A preliminary estimate of the unit evolutionary period for this enzyme is 3.25 million years. The method of determining immunological distances which was used in this study is compared to the method of microcomplement fixation in the Discussion.

Dissociation-recombination of sunflower seed acid phosphatase

Formal genetic studies of sunflower (Helianthus annuus) seed acid phosphatase (ACP, E.C. 3.1.3.2) had suggested that the functional enzyme consists of two polypeptide subunits. The dimeric quaternary structure was demonstrated by dissociation-recombination procedures. Dissociation of electrophoretically distinct homodimers was effected upon freezing of extracts in a pH 8-9 buffer containing 1 M NaCl and 0.1 M 2-mercaptoethanol. Reassociation, as indicated by the formation of the hybrid isozyme, occurred during 12 hr dialysis against a pH 7.0 buffer.

Portions of the central nervous system controlling reproductive behavior in Drosophila melanogaster

Drosophila melanogaster sex mosaics were tested in their courtship interactions with females and then with males. The distribution of genetically male and female tissues in each mosaic was determined with respect to an external cuticle marker and an internal enzyme marker. Performance of malelike courtship was correlated with the genotype of various tissues, with special attention being paid to the genotypes of head and thoracic ganglia. Male tissue in the left or right dorsal brain is necessary and nearly always sufficient to trigger early courtship actions--following of females and wing extension at them--but male tissue in both the dorsal brain and thoracic ganglia is necessary for attempted copulation to occur. Female tissue on or in the abdomen is nearly always necessary and sufficient for a mosaic to be courted by a male.

THE GENETIC CONTROL OF SUNFLOWER SEED ACID PHOSPHATASE

Genetic studies indicate that the acid phosphatase isozymes in seeds of the annual sunflower (Helianthus annuus) are specified by a single gene, Acp, having at least four codominant alleles, S, B, I and F. The enzyme is presumably dimeric. The polypeptide subunits in heterozygotes form an intragenic heterodimer in addition to two homodimers. Acp is not linked to either of the genes coding for seed alcohol dehydrogenase, Adh-1 and Adh-2, and these are not linked to each other. Acp therefore provides a molecular marker for a third sunflower linkage group. The estimated molecular weight of the intact, functional enzyme is about 95,000 daltons.

Preparation of specific antisera to Drosophila acid phosphatase without rigorous protein purification

Extracts from an acid phosphatase CRM- null mutant of Drosophila melanogaster were used to eliminate contaminating antibodies in a nonspecific preparation of anti-acid phosphatase serum. This method of producing specific antisera makes unnecessary the rigorous purification of an antigen prior to immunization attempts in those cases where CRM- null mutants of the antigen are available. Antisera so prepared could be used for a wide variety of purposes.