Observations onltl (lethal tumorous larvae) ofDrosophila melanogaster

A line ofGardner's tumorous head stock ofDrosophila melanogaster which is known to contain the inversion In (3L) Payne at varying frequencies, was found to be homozygous for another inversion, probably In (2L)t. The Payne inversion in this line is lethal when homozygous, and is balanced over a recessive lethal gene for which the symbolltl (lethal tumorous larvae) is proposed.ltl is located to the left ofRoughened on the basis of preliminary crossover tests.Homozygousltl larvae fail to pupate. They survive in the larval state for several days after pupation age. They exhibit a characteristic syndrome of abnormalities, part of which develops gradually during post-pupation age. Typical features of this syndrome are: over-abundance of blood cells, disintegration of fat-body, salivary gland, and parts of the gut, and the presence of brown or black masses (tumours). The absolute number of blood cells, and the proportion of different types of blood cells, further, the histolytic changes, in over-agedltl larvae are suggestive of changes which in normal development take place during metamorphosis. A striking feature ofltl are the melanotic pseudo-tumours. These usually float in the haemolymph; sometimes they are associated with organs. Tumour incidence is strongly influenced by genetic modifiers.A bacterial infection was found inltl. The infection is the consequence, rather than the cause, of some degenerative changes.The polytene chromosomes in salivary glands, Malpighian tubules, and parts of the gut ofltl larvae show striking abnormalities in their structure. They are shortened and thickened, and in advanced stages may assume a heterochromatine-like aspect through disintegration of the banding pattern. The changes resemble those found in conjunction with microbial infection inRhynchosciara andChironomus. In maleltl larvae the single X chromosome (in contrast to th double X in females) shows heterocyclic behaviour in that it is much shorter, wider, and fuzzier than the autosomes.Some aspects of the complex pleiotropic pattern of pathological changes inltl are discussed. Most abnormalities, including those of the chromosomes, are seen as an indirect effect, depending on physiological conditions in over-aged larvae. This is supported by observations on over-aged larvae of certain mutant types, or following treatment with 5-fluorouracil, which show similar chromosome changes. Several arguments support the view, thatltl larvae fail to pupate because of malfunction of the ring gland. Inability of the hypoderm to react is, however, not excluded as a possible explanation. Results of some transplantation experiments are included in the discussion. They show thatltl imaginal disks are capable of developing into adult organs.     

Proteins of the brain and body wall in larvae ofDrosophila melanogaster

Proteins of the brain and body wall cells of third instar larvae ofDrosophila melano-gaster have been examined by two-dimensional gel electrophoresis. Out of over 600 [³⁵ S ]-labelled peptide spots seen in brain or body wall extracts, 517 were common to both; 61 spots were unique to brain and 66 unique to muscle. Glycoproteins were identified by soaking the gels in radioactive iodinated Concanavalin-A. Forty four Con-A binding glycoproteins were identifiable in the brain and 41 in the muscle extracts. Out of these, 8 glycoproteins of the brain and 8 of muscles appear to be tissue-specific.     

The in vitro induction of puffing in salivary glands of the mutantl (2)gl ofDrosophila melanogaster by ecdysone

Summary Salivary glands of 9–10 day oldlethal giant larvae (l(2)gl, 2–0.0) respond to culture with ecdysone in a similar manner to mid third instar glands from wild type larvae. In particular, the ecdysone dependent puffs characteristic of pupariation, not previously observed in this mutant, are immediately induced. The secretion of the stored glue granules into the lumen of the salivary glands is also induced by ecdysone inl(2)gl.     

Development of cuticular patterns in the legs of a cell lethal mutant ofDrosophila melanogaster

Summary The development of cuticular patterns in the legs ofDrosophila melanogaster was studied in the temperature-sensitive cell autonomous lethal mutant1 (1)ts726 by treating animals with heat pulses of two days' duration at different developmental stages, in order to find out whether or not models which account for regulation of imaginal discs in the late third instar also hold for earlier developmental periods. Eight kinds of phenotypes were found, each of which occurred only after heat pulses that started at particular time: (1) complete and incomplete mirror image duplications of mesothoracic legs: early second instar; (2) homoeotic transformation to wing hinge in mesothoracic legs: early second instar; (3) prothoracic leg fusions: early second instar; (4) hypertrophied sex combs: early third instar; (5) outgrowths: early third instar; (6) sex comb teeth on second tarsal segment: early third instar; (7) reversed bristle polarity in intersegmental membrane gaps: early third instar; (8) deleted individual bristles: middle of third instar. These phenotypes were compared with patterns predicted by two models that have been devised to account for regeneration data: the polar coordinate model, and the gradient-of-morphogenetic-potential model. Some of the data (especially the finding of circumferentially incomplete partial duplicates) are more readily predicted by the polar coordinate model, although neither model can be ruled out. Phenotypes (6) and (7) can be accounted for by postulating a tandemly repeated positional signal corresponding to tarsal segmentation. The homoeotic transformation may be due to a transdetermination event occurring in situ during regulative growth following cell death. Since deletion of individual sex comb teeth leads to altered sex comb rotation, it is suggested that adjacent sex comb tooth cells interact during rotation.Address until September 1978: Institute of Molecular Biology, Billrothstraße 11, 5020 Salzburg, Austria     

Comparative study of the ring glands from wild type and 1(2)gl mutant drosophila melanogaster

Structural and functional changes have been correlated during metamorphic degeneration of a single muscle fiber, the plantar retractor of G. mellonella, its axon, and their junctions to determine which features persist as long as muscle contractility. Changes commence simultaneously in muscle and nerve near cuticular attachments, and spread towards the center. Alterations associated with the muscle, including appearance of collapsed tracheoles and mitochondria with dense bodies, begin late in the last larval instar. Within 12 hours after pupal ecdysis some tracheolar withdrawal occurs, sarcoplasmic reticulum becomes reduced, and many mitochondria have dense bodies, dense membranes, or are enlarged. By 17–19 hours primary myofilaments and striations begin to disappear, microtubules and autophagic vacuole-like bodies appear, and phagocytes invade the muscle. It remains partially contractile upon electrically stimulating its nerve, the ventral nerve, until these changes spread throughout the fiber. Neuromuscular junction changes, including appearance of dense mitochondria and isolation bodies, begin late in the last larval instar. Junctions become fewer, and none remain in those muscle areas where tracheoles, sarcoplasmic reticulum, and primary myofilaments have disappeared. Preliminary studies on nerve discharge activity to the muscle suggest that nerve silence occurs at approximately the time when the muscle loses all contractility. In some axons isolation bodies appear and neurotubules are lost, other axons remain unchanged, and new ones develop later in the pupal state. Phagocytes invade the neural lamella and it disappears in the late pupa, but it reappears in the adult. The adult ventral nerve has over three times more axons and a thinner layer of glial cells than the larval nerve.     

Sensitivity of larvae of Drosophila melanogaster mutant mus(2)201G1 to various analgesics

Sensitivity of larvae from mutagen-sensitive mus(2)201G1 mutant of Drosophila melanogaster to analgin, amidopyrine and antipyrine (4-64 mkmol/ml of medium) was studied. Relative frequency of flies homozygous for this mutation after combined development of homozygous and heterozygous flies in the medium with the analgetic was used as a criterion for larval sensitivity. It is shown that sensitivity of homozygotes was significantly higher than that of heterozygotes to all three analgetics. Relative sensitivity of homozygotes increased with the elevation of drugs concentration. The data obtained demonstrate the mutagenicity of the analgetics tested for Drosophila.     

In situ settlement behaviour of damselfish (Pomacentridae) larvae

Settlement‐stage damselfish (Pomacentridae) larvae of 13 species in seven genera were obtained from light traps at Lizard Island, Great Barrier Reef, Australia. Behaviour, observed in situ by SCUBA divers, of 245 larvae (6–13 mm, L_S; 5–60 individuals per species) released individually within a few m of reefs during the day differed markedly among species. From 0–28% (range among 13 species) of individuals of each species swam away from the adjacent reefs without swimming to the reefs. Of those that swam to a reef, 0–75% settled. For three species, sufficient data were available to test the hypothesis that these percentages did not differ amongst reefs: the hypothesis was rejected in one species. From 0–75% of larvae that reached the reef were eaten, 0–63% subsequently left the reef and 0–60% were still swimming over the reef at the end of the observation period. Swimming speeds of all but one species were greater when swimming away from the reef than toward it. Most species exceeded average current speeds when swimming away from reefs, but not when swimming toward and over them. Average swimming depths were in the upper half of the water column for most species, and were somewhat greater where the water depths were greater. The time the larvae swam over the reef before settling and the distance swum varied greatly among species from 0 to a mean of 5.5 min and 43 m. Settlement habitats chosen differed amongst species, and in some species, they were very specific. Average settlement depth varied among species from 6–13.5 m. In one species, settlement depth varied between reefs. About half of the 53 observed interactions between larvae and reef resident fishes were predation attempts: fishes of eight species (six families) attacked larvae. The other interactions were aggressive approaches by 11 species of resident fishes, all but one of which were pomacentrids. Many of these aggressive interactions discouraged settlement attempts. Larvae of some species experienced no predatory or aggressive interactions, whereas in other species interactions averaged >0.6 per released larva. Species that swam more‐or‐less directly to settlement sites near the reef edge experienced more interactions. Even within the same family, settlement behaviour differed among species in nearly all measures.     

Complete replication of DNA in polytene nuclei of salivary glands ofDrosophila melanogaster

Summary Combined cytophotometric and autoradiographic experiments are performed on individual polytene salivary gland nuclei of X/X-female and X/Y-male larvae ofDrosophila melanogaster, DNA measurements of unlabeled nuclei reveal complete douplings of all 4C DNA quantity during polytenization. These new data do not agree with the hypothesis of heterochromatic underreplication.     

Differentiation capacities of the dorsal metathoracic (haltere) disc ofDrosophila melanogaster

Summary The mature haltere disc, when implanted into a larva of the same age, undergoes metamorphosis along with the host, and produces a haltere, haltere sclerite, notum III, and pleural process. Implants ordinarily form an inverted vesicle, into which the haltere is frequently everted, usually only partly. Many adventitious bristles may be formed which are not foundin situ. It was found thatsc may reduce, andmwh may increase the number of sensilla.On the basis of results obtained from transplanted disc fragments an organ map of the haltere disc was constructed, which shows the presumptive haltere area to be located in the posterio-central part of the disc, while the anterio-medial part forms the thoracic structures dorsal to the haltere, and the posterio-lateral part the thoracic structures ventral to it. The anlage of the adventitious bristles is probably within the notum area. The haltere anlage proper is concentric; the prospective distal capitellum is located in the center, and is surrounded by the anlagen of the more proximal segments.The organ map of the haltere disc is compared with that of other discs. Organ maps seem to be basically concentric. There is a close homology between the maps of the wing and the haltere disc.     

Control of polytenic replication in dipteran larvae. I. Increased number of cycles in a mutant strain of Drosophila melanogaster

Previous studies have demonstrated that a consistent maximum number of polytenic replication cycles occurs in the salivary gland nuclei of a wild-type strain of D. melanogaster. Since that number is achieved within the larval period, the DNA synthesis of the prepupal period is believed to be that of propagation of the final cycle. Photometric determinations have been made, in this study, of the salivary gland nuclei of larvae and prepupae of the tu-h strain in which the larval period has been extended as a consequence of delay or failure of pupation. The DNA values indicate that a higher maximum number of polytenic replications is achieved in such nuclei. It is inferred, thereby, that initiation of polytenic replication is a function of the larval state and, since it is terminated by the intervention of metamorphosis, a hormonal dependence is suggested.     

Dynamics of mating success in experimental groups ofDrosophila melanogaster (Diptera: Drosophilidae)

Determinants of male courtship success in Drosophila melanogasterwere examined in groups of five males sequentially presented with five individual females. Thirty-three percent of males never mated, while approximately half of the males mated two or three times. Rapid courtship initiation was associated with male success in early matings only. Male size was important for courtship outcome, but the size distributions of mating and nonmating males and their progeny numbers indicate balancing rather than directional selection on size- dependent courtship success.     

Cytological observations on mitotic and meiotic pairing in males ofDrosophila melanogaster withIn(1)sc 4 sc 8

A cytological study has been carried out on the pairing of the XY chromosomes in somatic cells and in spermatocytes of larvae ofDrosophila melanogaster. Two strains have been studied: one a control strain and the other a carrier of theIn(1)sc ⁴ sc ⁸ inversion on the X chromosome. The data obtained seem to indicate that the absence of the greater region of homology between XY, caused by the presence of theIn(1)sc ⁴ sc ⁸ inversion, results in an approximately equal reduction in the frequencies of mitotic and meiotic pairing of XY. The short arm of the Y chromosome shows marked differences in the pairing with the X chromosome, compared with the control, whereas the long arm shows no variations.     

Isozymic patterns and functional states of cell lines ofDrosophila melanogaster cultured in vitro. II

Summary Our previous isoenzyme investigation ofDrosophila melanogaster cell lines in vitro has been completed with twelve further enzyme systems. The enzyme profiles seem to be in good agreement with a previous hypothesis concerning the precise origin of these cell lines (probably from imaginal discs or nervous tissues). Our results have been summarized with reference to the biochemical genetic map ofDrosophila melanogaster in order to consider a possible functional organization of the genome.Abbreviations NAD nicotine adenine nucleotide - NADP nicotine adenine nucleotide phosphate - NBT nitroblue tetrazolium - PMS phenazine methosulfate - EDTA ethylene diamine tetraacetic acid - GOT Glutamate-oxaloacetate transaminase - PGK Phosphoglycerate kinase - GPDH -glycerophosphate dehydrogenase - MDH Malate dehydrogenase - PGM Phosphoglucomutase - Aph Alkaline phosphatase - MDH-NADP Malic enzyme - Lap Leucine Amino-Peptidase - LDH Lactate dehydrogenase - -1-OHDH L-3-hydroxyacid dehydrogenase - ADH Alcohol dehydrogenase - Aldox Aldehyde oxydase - 6PGD 6 Phosphogluconate dehydrogenase - G6PD Glucose-6-Phosphate dehydrogenase - Hex3 Fructokinase - IDH Isocitrate dehydrogenase - Est 6 Esterase 6 - Est C Esterase C - ODH Octanol dehydrogenase - XDH Xanthine dehydrogenase - AcPh Acid Phosphatase 1     

Characteristics of the endocrine system in Drosophila melanogaster 1 (2)gl mutants, differing in time of death]

A comparative study of the state of the endocrine system and one of the larval organs, the salivary gland, has been carried out in larvae homozygous for the 1(2)gl gene. They differ in time of death (death at the third larval instar--larval allele, and at the prepupal state--prepupal allele). It is shown that homozygotes for the larval and prepupal allele have underdeveloped prothoracal glands. Corpora allata in homozygotes for the larval allele does not differ from the norm. Corpora allata in homozygotes for the prepupal allele is decreased proportionally to the decrease of prothoracal glands. A decrease of gland size is due to a decrease of the volume of cell but not to their number; this decrease is accompanied by the decrease of their relative DNA content. Salivary glands in homozygotes are reduced and comprise 80% of the normal size in homozygotes for the prepupal allele and 50% for homozygotes for the larval allele. Polyteny level in the salivary gland nuclei is much decreased as compared with the normal level. DNA level is more reduced in larvae homozygous for the larval allele.