Male Reproduction Behavior in Drosophila melanogaster Strains with Different Alleles of the flamencoGene

The allelic state of gene flamenco has been determined in a number of Drosophila melanogaster strains using the ovo^D test. The presence of an active copy of gypsy in these strains was detected by restriction analysis. Then male reproduction behavior was studied in the strains carrying a mutation in gene flamenco. In these experiments mating success has been experimentally estimated in groups of flies. It has been demonstrated that the presence of mutant allele flam ^MS decreases male mating activity irrespective of the presence or absence of mutation white.The active copy of gypsy does not affect mating activity in the absence of the mutation in gene flamenco. Individual analysis has demonstrated that mutation flam ^MS results in characteristic changes in courtship: flam ^MS males exhibit a delay in the transition from the orientation stage to the vibration stage (the so-called vibration delay). The role of locus flamenco in the formation of male mating behavior in Drosophila is discussed.     

Some behavioral features in Drosophila melanogaster lines carrying a flamenco gene mutation]

Olfactory sensitivity and locomotor activity was assayed in Drosophila melanogaster strains carrying a mutation of the flamenco gene, which controls transposition of the mobile genetic element 4 (MGE4) retrotransposon the gypsy mobile element. A change in olfactory sensitivity was detected. The reaction to the odor of acetic acid was inverted in flies of the mutator strain (MS), which carried the flam mutation and active MGE4 copies and were characterized by genetic instability. Flies of the genetically unstable strains displayed a lower locomotor activity. The behavioral changes in MS flies can be explained by the pleiotropic effect of the flam mutation or by insertion mutations which arise in behavior genes as a result of genome destabilization by MGE4.     

Mobile Genetic Element gypsy(MDG4) in Drosophila melanogasterStrains: Structural Characteristics and Regulation of Transposition

Distribution of two structural functional variants of the gypsy(MDG4) mobile genetic element was examined in 44 strains of Drosophila melenogaster. The results obtained suggest that less transpositionally active gypsyvariant is more ancient component of the Drosophilagenome. Using Southern blotting, five strains characterized by increased copy number of gypsywith significant prevalence of the active variant over the less active one were selected for further analysis. Genetic analysis of these strains led to the suggestion that some of them carry factors that mobilize gypsyindependently from the cellular flamencogene known to be responsible for transposition of this element. Other strains probably contained a suppressor of the flam ^–mutant allele causing active transpositions of the gypsy. Thus, the material for studying poorly examined relationships between the retrovirus and the host cell genome was obtained.     

Potentially active copies of the gypsy retroelement are confined to the y chromosome of some strains of drosophila melanogaster possibly as the result of the female-specific effect of the flamenco gene

Gypsy is an endogenous retrovirus present in the genome of Drosophila melanogaster. This element is mobilized only in the progeny of females which contain active gypsy elements and which are homozygous for permissive alleles of a host gene called flamenco (flam). Some data strongly suggest that gypsy elements bearing a diagnostic HindIII site in the central region of the retrovirus body represent a subfamily that appears to be much more active than elements devoid of this site. We have taken advantage of this structural difference to assess by the Southern blotting technique the genomic distribution of active gypsy elements. In some of the laboratory Drosophila stocks tested, active gypsy elements were found to be restricted to the Y chromosome. Further analyses of 14 strains tested for the permissive vs. restrictive status of their flamenco alleles suggest that the presence of permissive alleles of flam in a stock tends to be associated with the confinement of active gypsy elements to the Y chromosome. This might be the result of the female-specific effect of flamenco on gypsy activity. Received: 13 June 1997 / Accepted: 27 August 1997     

The introduction of a transpositionally active copy of retrotransposon GYPSY into the Stable Strain of Drosophila melanogaster causes genetic instability

A previously described genetic system comprising a Mutator Strain (MS) and the Stable Strain (SS) from which it originated is characterized by genetic instability caused by transpositions of the retrotransposon gypsy. A series of genetic crosses was used to obtain three MS derivatives, each containing one MS chromosome (X, 2 or 3) in the environment of SS chromosomes. All derivatives are characterized by elevated frequencies of spontaneous mutations in both sexes. Mutations appear at the premeiotic stage and are unstable. Transformed derivatives of SS and another stable strain 208 were obtained by microinjection of plasmid DNA containing transpositionally active gypsy inserted into the Casper vector. In situ hybridization experiments revealed amplification and active transposition of gypsy in SS derivatives, while the integration of a single copy of gypsy into the genome of 208 does not change the genetic properties of this strain. We propose that genetic instability in the MS system is caused by the combination of two factors: mutation(s) in gene(s) regulating gypsy transposition in SS and its MS derivatives, and the presence of transpositionally active gypsy copies in MS but not SS.     

Study of Male Mating Behavior in SomeDrosophila melanogaster Strains in Experiments with Fertilized Females

Male courtship ritual is among the main behavioral characteristics of Drosophila. This is a complex, genetically determined process consisting of four general stages: orientation, vibration, licking, and attempts at copulation (or successful copulation). Several genes are known that control some stages of this behavior. Most of them have pleiotropic effects and are involved in other biological processes. Earlier, we have shown that a mutation in locus flamenco (20A1-3), which controls transposition and infectivity of retrotransposongypsy (MDG4), is involved in the genetic control of behavior. In strains mutant for this locus, the male mating activity is decreased and the structure of courtship ritual is changed. To understand the mechanisms of these changes, it is important to study all behavioral stages in genetically identical strains. For this purpose, the normal allele of geneflamenco from the X chromosome of the wild-type strain Canton S was introduced into strain SS carrying flam ^MS. This offers new opportunities in studying the role of gene flamenco in the control of mating behavior in Drosophila.     

Autonomous transposition of gypsy mobile elements and genetic instability in Drosophila melanogaster

Summary The laboratory imitator strain (MS) of Drosophila melanogaster is characterized by an elevated frequency of spontaneous mutation (10^–3–10^–4). Mutations occur in both sexes at premeiotic stages of germ cell development. The increased mutability is a characteristic feature of MS itself, since it appears in the absence of outcrossing. Most of the mutations arising in this strain are unstable: reversions to wild type, high frequency mutation to new mutant states and replicating instability were observed. We have investigated the localization of the transposable genetic elements mdg1, 412, mdg3, gypsy (mdg4), copia and P in the X chromosomes of the MS and in the mutant lines y, ct, sbt derived from it by in situ hybridization. The P element was not found in any of these strains. The distributions of mdg1, 412, mdg3 and copia were identical in the X chromosomes of the MS and its derivatives. However, the sites of hybridization with gypsy differ in the various lines tested. In the polytene chromosomes of MS animals significant variation in location and number of copies of the gypsy element was demonstrated between different larvae; copy numbers as high as 30–40 were observed. These results suggest autonomous transposition of gypsy in the MS genome while several other mobile elements remain stable.     

Morphological and molecular characterization of new drosophila cell lines established from a strain permissive for Gypsy transposition

Summary The gypsy element of Drosophila melanogaster is the first retrovirus identified in invertebrates. Its transposition is controlled by a host gene called flamenco (flam): restrictive alleles of this gene maintain the retrovirus in a repressed state while permissive alleles allow high levels of transposition. To develop a cell system to study the gypsy element, we established four independent cell lines derived from the Drosophila strain SS, which contains a permissive allele of flamenco, and which is devoid of transposing copies of gypsy. The ultrastructural analysis of three SS cell lines revealed some remarkable characteristics, such as many nuclear virus-like particles, cytoplasmic dense particles, and massive cisternae filled with a fibrous material of unknown origin. Gypsy intragenomic distribution has been compared between the three cell lines and the original SS fly strain, and revealed in two of the cell lines an increase in copy number of a restriction fragment usually present in active gypsy elements. This multiplication seems to have occurred during the passage to the cell culture. Availability of SS cell lines should assist studies of gypsy transposition and infectivity and might be useful to produce high amounts of gypsy viral particles. These new lines already allowed us to show that the Envelope-like products of gypsy can be expressed as membrane proteins.     

Structural organization characteristics of the <Emphasis Type="Italic">DIP1</Emphasis> gene in <Emphasis Type="Italic">Drosophila melanogaster</Emphasis> strains mutant for the <Emphasis Type="Italic">flamenco</Emphasis> gene

Molecular cloning of the DIP1 gene located in the 20A4-5 region has been performed from the following strains with the flamenco phenotype: flam ^SS (SS) and flam ^MS (MS) characterized by a high transposition rate of retrotransposon gypsy (mdg4), flam ^{py + (P)} carrying the insertion of a construction based on the P element into the region of the flamenco gene, and flamenco ⁺. The results of restriction analysis and sequencing cloned DNA fragments has shown that strains flam ^SS , flam ^MS considerably differ from flam ^{py + (P)}, and flamenco ⁺ in the structure of DIP1. Strains flam ^SS and flam ^MS have no DraI restriction site at position 1765 in the coding region of the gene, specifically, in the domain determining the signal of the nuclear localization of the DIP1 protein. This mutation has been found to consist in a nucleotide substitution in the recognition site of DraI restriction endonuclease, which is transformed from TTTAAA into TTTAAG and, hence, is not recognized by the enzyme. This substitution changes codon AAA into AAG and is translationally insignificant, because both triplets encode the same amino acid, lysine. The DIP1 gene of strains flam ^SS and flam ^MS has been found to contain a 182-bp insertion denoted IdSS (insertion in DIP1 strain SS); it is located in the second intron of the gene. The IdSS sequence is part of the open reading frame encoding the putative transposase of the mobile genetic element HB1 belonging to the Tc1/mariner family. This insertion is presumed to disturb the conformations of DNA and the chromosome, in particular, by forming loops, which alters the expression of DIP1 and, probably, neighboring genes. In strains flamenco ⁺ and flam ^{py + (P)}, the IdSS insertion within the HB1 sequence is deleted. The deletion encompasses five C-terminal amino acid residues of the conserved domain and the entire C-terminal region of the putative HB1 transposase. The obtained data suggest that DIP1 is involved in the control of gypsy transpositions either directly or through interaction with other elements of the genome.     

Retrotransposons IDEFIX and ZAM are responsible for transposition in Drosophila melanogaster MS strain mutant for the flamenco gene

Transposition activity of Drosophila melanogaster gypsy retrotransposon is controlled by the flamenco locus. Transposition activity of the gypsy, ZAM, Idefix, springer, nomad, rover, Quasimodo, 17.6, 297, and Tirant retrotransposons was investigated in isogenic SS and MS strains of D. melanogaster mutant for the flamenco gene. It has been shown that gypsy, ZAM, and Idefix have different genomic surrounding in the studied strains that evidences to their transposition in these strains.     

The introduction of a transpositionally active copy of retrotransposon GYPSY into the Stable Strain of Drosophila melanogaster causes genetic instability

A previously described genetic system comprising a Mutator Strain (MS) and the Stable Strain (SS) from which it originated is characterized by genetic instability caused by transpositions of the retrotransposon gypsy. A series of genetic crosses was used to obtain three MS derivatives, each containing one MS chromosome (X, 2 or 3) in the environment of SS chromosomes. All derivatives are characterized by elevated frequencies of spontaneous mutations in both sexes. Mutations appear at the premeiotic stage and are unstable. Transformed derivatives of SS and another stable strain 208 were obtained by microinjection of plasmid DNA containing transpositionally active gypsy inserted into the Casper vector. In situ hybridization experiments revealed amplification and active transposition of gypsy in SS derivatives, while the integration of a single copy of gypsy into the genome of 208 does not change the genetic properties of this strain. We propose that genetic instability in the MS system is caused by the combination of two factors: mutation(s) in gene(s) regulating gypsy transposition in SS and its MS derivatives, and the presence of transpositionally active gypsy copies in MS but not SS.     

Increased size due to larval royal jelly exposure does not affect circadian locomotor activity or climbing ability in adult female Drosophila melanogaster

The effects of royal jelly (RJ) appear to be conserved in Drosophila; flies exposed of RJ exhibit increased body size, similar to queen bees. However, in flies and bees, there is evidence that increased body size can lead to impairments to locomotor activity, while RJ may have anti-fatigue properties. Canton-S and Oregon-R Drosophila larvae were raised on media containing 0% or 20% pure RJ. Climbing assays were conducted to assess vertical locomotion. Circadian locomotion was observed using Drosophila Activity Monitors. CS, but not Or-R, raised on RJ were larger compared to controls. Flies exposed to RJ exhibited entrainment and free-running rhythms. The increased size due to RJ exposure in this study had no bearing on circadian locomotor activity or climbing. These results indicate that there is variation among physiological responses to RJ among different strains, but RJ was equally ineffective in affecting locomotor behavior no matter the physiological response.     

Age Dynamics of Adult Fly Activity in Drosophila Strains with Apoptosis Deregulation after Larval Exposure to Chronic Irradiation

The relationship was studied between radiation-induced apoptosis in the nervous system of Drosophila larvae and the age dynamics in adult fly neuromuscular activity. The level of apoptosis in the neural ganglia of third-instar larvae from the wild-type strain increased 2.5 times after larval exposure to ionizing radiation (54 cGy). Irradiation of the strain with enhanced sensitivity to apoptosis induction, which carries a mutation in gene–inhibitor of apoptosis th (allele th ⁴), and the wild-type strain Berlin led to an increase in neuromuscular activity of adult flies throughout the experiment and, consequently, to reduced aging rate. Conversely, this effect was not observed in strains with reduced sensitivity to induction of apoptosis (with mutations in genes dArk and Dcp-1).     

Rhythm-Specific Mutations in Drosophila rajasekari Altered Adult Locomotor Activity Rhythm but Not Eclosion Rhythm

The early and late strains for phase angle difference (Φ) of adult locomotor activity in Drosophila rajasekari were developed by artificial selection; these strains differed in Φ, activity pattern, activity level, free-running period (τ) in constant darkness (DD) and light induced phase shifts from those of the wild type (Joshi, 1998). The present studies were designed to determine whether or not the psi-mutations for adult locomotor activity rhythm had also altered the fundamental properties of the eclosion rhythms in these strains. The circadian rhythms of eclosion have been studied in the wild type, the early and late strains. In contrast to the effects on the locomotor activity rhythms in the early and late strains, the psi-mutations have no apparent effect on the eclosion median in light-dark cycles of 12 : 12 h, on τ in DD, light induced phase shifts or subjective light sensitivity in these strains. Thus the psi-mutations for the adult locomotor activity rhythms in D. rajasekari appear to be rhythm-specific mutations altering the locomotor rhythms but not the eclosion rhythms.     

Developmental plasticity of the locomotor activity rhythm of Drosophila melanogaster

We used four replicate outbred populations of Drosophila melanogaster to investigate whether the light regimes experienced during the pre-adult (larval and pupal) and early adult stages influence the free-running period (τ_DD) of the circadian locomotor activity rhythm of adult flies. In a series of two experiments four different populations of flies were raised from egg to eclosion in constant light (LL), in light/dark (LD) 12:12 h cycle, and in constant darkness (DD). In the first experiment the adult male and female flies were directly transferred into DD and their locomotor activity was monitored, while in the second experiment the locomotor activity of the emerging adult flies was first assayed in LD 12:12 h for 15 days and then in DD for another 15 days. The τ_DD of the locomotor activity rhythm of flies that were raised in all the three light regimes, LL, LD 12:12 h and in DD was significantly different from each other. The τ_DD of the locomotor activity rhythm of the flies, which were raised in DD during their pre-adult stages, was significantly shorter than that of flies that were raised as pre-adults in LL regime, which in turn was significantly shorter than that of flies raised in LD 12:12 h regime. This pattern was consistent across both the experiments. The results of our experiments serve to emphasise the fact that in order to draw meaningful inferences about circadian rhythm parameters in insects, adequate attention should be paid to control and specify the environment in which pre-adult rearing takes place. The pattern of pre-adult and early adult light regime effects that we see differs from that previously observed in studies of mutant strains of D. melanogaster, and therefore, also points to the potential importance of inter-strain differences in the response of circadian organisation to external influences.     

Retrotransposon Gypsy and genetic instability in Drosophila (review)

The laboratory mutator strain (MS) has properties which can be characterized as genetic instability. It exhibits the high level of gypsy autonomous transposition in somatic and germ cells. This paper summarizes all the data concerning this system and gypsy itself that has been obtained in our works during the last years.     

N‐β‐alanyldopamine metabolism,locomotor activity and sleep in Drosophila melanogaster ebony and tan mutants

Drosophila melanogaster Meigen mutants for N‐β‐alanyldopamine (NBAD) metabolism have altered levels of NBAD, dopamine and other neurotransmitters. The ebony¹ mutant strain has very low levels of NBAD and higher levels of dopamine, whereas the opposite situation is observed in the tan¹ mutant. Dopamine is implicated in the control of movement, memory and arousal, as well as in the regulation of sleep and wakefulness in D. melanogaster. N‐β‐alanyldopamine, which is best known as a cuticle cross‐linking agent, is also present in nervous tissue and has been proposed to promote locomotor activity in this fly. The daily locomotor activity and the sleep patterns of ebony¹ and tan¹ mutants are analyzed, and are compared with wild‐type flies. The tan¹ mutant shows reduced locomotor activity, whereas ebony¹ shows higher levels of activity than wild‐type flies, suggesting that NBAD does not promote locomotor activity. Both mutants spend less time asleep than wild‐type flies during night‐time; ebony shows more consolidated activity during night‐time and increased sleep latency, whereas tan is unable to consolidate locomotor activity and sleep in either phase of the day. The daily level of NBAD‐synthase activity is measured in vitro using wild‐type and tan¹ protein extracts, and the lowest NBAD synthesis is observed at the time of higher locomotor activity. The abnormalities in several parameters of the waking/sleep cycle indicate some dysfunction in the processes that regulates these behaviours in both mutants.