David B. Roberts

Drosophila: the genetics of two major larval proteins

A series of irradiation-induced deficiencies covering 62 polytene chromosome bands in chromosome arm 3L of Drosophila melanogaster includes the loci of two abundant developmentally regulated larval proteins. The structural gene for larval serum protein 2 (LSP 2) lies at 68E3 or 4, and that for salivary glue secretion protein 3 between 68A8 and 68C11, coincident with a major intermoult puff active in the salivary gland at the time of glue synthesis. The structural genes for esterase 6 and four visible recessive loci lie within the same region.

The developmental profiles of two major haemolymph proteins from Drosophila melanogaster.

Abstract There are four major protein species in the haemolymph of the late 3rd instar of Drosophila . Two of these, LSP-1 and LSP-2, have been studied in detail. Larvae, pupae, and flies of different ages were measured for wet weight, total extractable protein and using an immunoassay, the amounts of LSP-1 and LSP-2. The synthesis of both proteins begins after the 2nd larval ecdysis and at puparium formation they represent 9% and 1.5% of total extractable protein. This value remains constant during the first part of metamorphosis, then falls rapidly. The function of these proteins and their suitability as systems for the study of gene control and protein synthesis in Drosophila are discussed.

Cloning and sequence analysis of GmII, a Drosophila melanogaster homologue of the cDNA encoding murine Golgi α-mannosidase II

Abstract Using the murine cDNA that encodes Golgi α-mannosidase II (GlcNAc transferase I-dependent α1,3 [α1,6] mannosidase; EC 3.2.1.114) as a probe to screen a cDNA library made from Drosophila melanogaster (Dm) embryos, we have isolated GmII, the Dm sequence homologue. The 3926-bp cDNA has an open reading frame of 3327 bp and predicts a polypeptide of approx. 127 kDa, a mass similar to that of the murine protein. The deduced mouse and Dm amino acid (aa) sequences share extensive similarity across their entire lengths and are both type-II transmembrane (TM) proteins with short cytoplasmic tails, single TM domains and large hydrophilic C-terminal domains. A region of approx. 200 aa, within the C-terminal domain, has considerable similarity to a corresponding region from several other α-mannosidases. GmII has been localized to a single site (85D14-18) on the right arm of chromosome 3.

Drosophila hemolymph proteins: Purification, characterization, and genetic mapping of larval serum protein 2 in D. melanogaster

Three of the major protein species present in the hemolymph of Drosophila melanogaster larvae just prior to pupation are absent from second instar larvae but accumulate rapidly during the third instar. This article describes the purification and characterization of one of these, larval serum protein (LSP) 2, using an immunological assay. It is a homohexamer of molecular weight about 450,000, with a polypeptide molecular weight of 78,000–83,000. Fast and slow electrophoretic variants of this protein map between the markers vin and gs, at 36–37 on chromosome 3.

Drosophila melanogaster: the model organism

In the 20th century, there were two decades during which Drosophila melanogaster was the most significant model organism and each decade led to the establishment of new scientific disciplines. The first decade was roughly from 1910 and during this period a small group at Columbia University, headed by Thomas Hunt Morgan, established the rules of transmission genetics with which we are all familiar. In the second decade, roughly from 1970, many of the principles and techniques of the earlier period were used to determine the genetic control of basic aspects of the biology of organisms, notably their development and their behaviour. In this review I will show that it was not only the genius of the research workers (five were awarded Nobel Prizes and it has been argued, with justification, that at least one more should have been awarded) but also the special features of D. melanogaster that led to these advances. While Drosophila is still a significant model organism, the advent of molecular biology permits the investigation of organisms less amenable to genetic analysis, but the principles applied in these investigations were in the main principles laid down during the earlier work on Drosophila.

Quantitative in situ hybridization reveals extent of sequence homology between related DNA sequences in Drosophila melanogaster

Cloned DNA from the larval serum protein one (LSP-1) genes was hybridized to polytene chromosomes of D. melanogaster. The ratio of grains deposited over any two of the three LSP-1 genes with any one LSP-1 subunit probe was constant. Varying the gene dose of any one LSP-1 subunit relative to the others by up to six fold gave a linear relationship of grain ratios to gene ratios. We show that these constant ratios closely reflect the extent of sequence homology between the genes as determined by heteroduplex mapping (Smith et al., 1981) and thermal denaturation studies. The results obtained demonstrate that the LSP-1 subunit genes are present in equal copies in the genome.

Nucleotide sequence of a Drosophila melanogaster cDNA encoding a calnexin homologue

A cDNA which encodes a calnexin (Cnx)-like protein from Drosophila melanogaster has been characterized. The deduced amino acid sequence shares several regions of homology with Cnx from other sources with two conserved motifs each repeated four times. The gene was found to be transcribed in various tissues and at all developmental stages. We have mapped the gene at chromosomal position 99A and we have also mapped the related gene coding for Drosophila calreticulin at 85E.

An immunological and electrophoretic study of the larval serum proteins of Drosophila species

Abstract The larval serum proteins (LSPs) from fifteen Drosophila species were analysed on sodium dodecyl sulphate (SDS) polyacrylamide gels and on non-denaturing polyacrylamide gels. The LSPs were identified immunologically after transfer of the proteins from the gels to nitrocellulose filters. All species possessed LSP-2 and LSP-1 γ-like proteins and in addition have at least one other LSP-1-like protein. These results are discussed in the light of studies using nucleic acid hydridization to detect LSP sequences in these species.

Synthesis of larval serum proteins 1 and 2 of Drosophila melanogaster by third instar fat body

Abstract Larval serum proteins (LSPs) 1 and 2 of Drosophila melanogaster have been shown to accumulate in third instar larval haemolymph ( Roberts et al. , 1977). In the present paper the major third instar larval tissues have been assayed for LSP synthesis. Polypeptides radiolabelled in organ culture have been analyzed by SDS-polyacrylamide gel electrophoresis and by immunoelectrophoresis. Fat body was shown to be the major source of LSPs 1 and 2 and the two proteins were synthesized by all regions of third instar fat body.

Chapter 6 Drosophila Antigens: Their Spatial and Temporal Distribution, Their Function and Control

Publisher Summary This chapter discusses the protein molecules of different types of cells at different stages of development, the role played by these molecules in the changes that occur during development, and the control of the synthesis of these molecules. The development of an organism is accompanied by the changing pattern of proteins (both quantitative and qualitative) that reflects the differential gene activity and that the different cell types are associated with different patterns of proteins, again reflecting the differential gene activity. The proteins of Drosophila change during development and are different in different tissues or cells. The most essential proteins are found in all cells at all times, while most luxury proteins are found in limited cell types and at the limited stages of development. The chapter describes the effect of mutation on the protein pattern of developing Drosophila . Mutations, affecting the development of Drosophila, frequently lead to the absence of a protein. Different cell lines respond in a different way to external stimuli, as hormones. With the use of cell lines derived from the stocks carrying appropriate mutants, it may be possible to use these techniques to investigate the mechanism of hormone action and gene control. Finally, the immediate control of gene activity in response to an external stimulus can be investigated, either by the study of mutants that fail to respond to that stimulus or by selecting mutants of the cultured cells that fail to respond.