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PubMedDate not supplied

Restoration of circadian behavioural rhythms by gene transfer in Drosophila.

The per locus of Drosophila melanogaster has a fundamental role in the construction or maintenance of a biological clock. Three classes of per mutations have been identified: per mutants have circadian behavioural rhythms with a 29-h rather than a 24-h period, pers mutants have short-period rhythms of 19 h, and per mutants have no detectable circadian rhythms. Each of these mutations has a corresponding influence on the 55-s periodicity of male courtship song. Long- and short-period circadian rhythm phenotypes can also be obtained by altering the dosage of the wild-type gene: for example, females carrying only one dose of this X-linked gene have circadian rhythms with periodicities about 1 h longer than those carrying two doses. In a previous report, cloned DNA was used to localize several chromosomal rearrangement breakpoints that alter per locus function. The rearrangements all affected a 7-kilobase (kb) interval that encodes a 4.5-kb poly(A)+ RNA. We report here that when a 7.1-kb fragment from a per+ fly, including the sequences encoding the 4.5-kb transcript, is introduced into the genome of a per (arrhythmic) fly by P element-mediated transformation, circadian rhythmicity of behaviour such as eclosion and locomotor activity is restored. The transforming DNA complements per locus deletions and is transcribed, forming a single 4.5-kb poly(A)+ RNA comparable to that produced by wild-type flies.

Animals↗
PubMedDate not supplied

Action potential mutations stop a biological clock in Drosophila.

The Drosophila melanogaster male produces a species-specific courtship song by wing vibration. The most conspicuous feature of the song is a series of pulses with a 30-40-ms interpulse interval (IPI) which oscillate in wild-type males with a period of 50-60 s. This short-term biological rhythm in IPI is influenced by several gene mutations at the period (per) locus, which alter the normal 24-h free-running period of the circadian clock and have corresponding effects on the song cycle. The present study reveals that, under restrictive conditions, temperature-sensitive mutations which affect neuronal membrane excitability seem to stop the biological clock underlying the fruitfly's song rhythm.

Action Potentials↗
PubMedDate not supplied

An unusual coding sequence from a Drosophila clock gene is conserved in vertebrates.

The per locus has a fundamental involvement in the expression of biological rhythms in Drosophila. Mutations at this locus can shorten, lengthen or eliminate a variety of rhythmic activities that range from circadian behaviours, exemplified by eclosion and locomotor activities, to short-period behaviour such as the 55-s rhythm of courtship song. DNA from the per locus has been cloned, and we have used P-element-mediated DNA transformation to establish that a 7.1-kilobase(kb) HindIII fragment contains a functional copy of the gene. This transforming DNA contains a single transcription unit which gives rise to a 4.5-kb poly(A)+ RNA. Here we report the results of a search for sequences homologous to the per locus DNA in the genomic DNA of several species of vertebrates. An unusual, tandemly repeated sequence forming a portion of the 4.5-kb per transcript is homologous to DNA in chicken, mouse and man. Cloned DNAs from the mouse and Drosophila are related by long, uninterrupted tandem repetitions of the sequence ACNGGN. At the per locus, these tandem repeats are predicted to code for poly(Thr-Gly) tracts up to 48 amino acids long. These repeated sequences are also transcribed in the mouse. Several long tracts of poly(Thr-Gly) appear to be encoded by DNA cloned from the mouse.

Amino Acid Sequence↗
PubMedDate not supplied

Product of per locus of Drosophila shares homology with proteoglycans.

Genes controlling biological rhythms have been identified in Drosophila. The best characterized of these genes is called period (per). Although wild-type flies have daily (circadian) rhythms with a periodicity of approximately 24 h, pers and per1 mutants have 19-h and 29-h rhythms, respectively, and pero mutants are arrhythmic. The pers mutation also enhances the sensitivity of the circadian clock to resetting by light stimuli, and all three types of per mutations affect a much shorter period ultradian rhythm, the 55-s rhythm of the Drosophila courtship song. A fragment of DNA of approximately 7 kilobases (kb) encoding a 4.5-kb poly(A)+ RNA restores rhythmicity when transduced into Drosophila carrying mutations or chromosomal deletions of the per locus. Here we report the sequence of this biologically active segment of DNA. The transcription unit that encodes the 4.5-kb RNA has been mapped, permitting a conceptual translation of a protein of 1,127 amino acids. Several abnormal phenotypes characterized by long-period rhythms are associated with changes in the sequence of untranslated portions of the transcription unit. The structure of some segments of the predicted protein suggests that it is a proteoglycan.

Amino Acid Sequence↗
PubMed1988

Embryonic temperature determines adult sexuality in a reptile.

Gonadal differentiation in amniote vertebrates is controlled by one of two mechanisms: genotypic sex determination (GSD) or environmental sex determination (ESD). After differentiation the fetal gonad produces sex steroid hormones which govern the development of other components of sexuality. Thus, the primary sex determiner is thought to operate solely as a trigger that initiates a cascade of events culminating in adult sex differences. In the leopard gecko (Eublepharis macularius), gonadal and morphological sex is determined by incubation temperature, with relatively 'hot' temperatures (32 degrees C) resulting in mostly male offspring and relatively 'cold' temperatures (26 degrees C) resulting in only female offspring. We report here that the reproductive behaviour and endocrine physiology of an adult is influenced by the temperature experienced as an embryo. Also, the perception of a female to courtship by a male is influenced by incubation temperature. These data indicate that incubation temperature, the primary determiner of sex in this species, has differential effects on adult sexuality.

Animals↗
PubMed1990

Sexual selection for sensory exploitation in the frog Physalaemus pustulosus.

The sensory bases of species and population mate preferences are well known; in frogs properties of the female auditory system influence such preferences. By contrast, there is little understanding of how sensory characteristics could result in sexual selection within a population. One possible mechanism is that females are more sensitive to male courtship signals that deviate from the population mean. We document this mechanism in the frog Physalaemus pustulosus. Female basilar papilla tuning is biased toward lower-than-average frequencies in the 'chuck' portion of the male's call, explaining female preference for the lower-frequency chucks produced by larger males. The tuning does not differ between P. pustulosus and its close relative P. coloradorum, a species in which males never evolved the ability to produce chucks; thus the female tuning evolved before the chuck and therefore the chuck played no role in the evolution of the preference. This allows us to reject two popular hypotheses for the evolution of this female preference (runaway sexual selection and natural selection) in favour of a third: sexual selection for sensory exploitation.

Animals↗
PubMed2000

Formation of the male-specific muscle in female Drosophila by ectopic fruitless expression.

The Drosophila fruitless (fru) gene product Fru has been postulated to be a neural sex-determination factor that directs the development of at least two male-specific characteristics, namely courtship behaviour and formation of the muscle of Lawrence (MOL). The fru gene encodes a putative transcription factor with a BTB domain and two zinc-finger motifs, and with consensus Tra-binding sequences. The binding of Tra to these sequences results in sex-specific alternative splicing of the fru mRNA, leading to production of the 'male-type' or 'female-type' Fru protein. We show here that the Fru protein is not detected in the female central nervous system (CNS), despite the similar level of expression of fru mRNA in both male and female CNS. As ectopic expression of both the 'male-type' (with the sequence for the amino-terminal extension) and 'female-type' (without the sequence for the amino-terminal extension) fru cDNA can induce formation of the MOL in females, the presence or absence of the Fru protein, and not its sex-specific structure, seems to be responsible for the sexually dimorphic actions of the fru gene.

Alleles↗
PubMed1982

Evolution of Drosophila on the newer Hawaiian volcanoes.

The 20-year odyssey taken by the Hawaiian Drosophila project has recently become focussed on a selected microcosm: this consists of the Island of Hawaii ("the Big Island") and one of its endemic species. Drosophila silvestris. Both the island and the species are considerably less than one million years old. Along with a morphologically distinct, but partially sympatric, close relative, D. heteroneura, silvestris inhabits moderate-altitude rainforests. They are the only members of the planitibia subgroup that occur on this island. The distribution of these species discontinuous due to the dissection of the forests by recent lava flows and to the irregular distribution of their main host plants. Although allozyme heterozygosity within both species is considerable, local populations of both species show high similarity coefficients. The two species are, furthermore, virtually indistinguishable electrophoretically; nevertheless, significant differences in single-copy DNA have been demonstrated. Within silvestris, five inversion polymorphisms are widespread; six others have more restricted distributions. Populations in some of the geologically newer areas are the most polymorphic, both chromosomally and morphologically. Altitudinal clines of gene arrangement frequency are clear in areas on both sides of the island. The same inversions are involved in these clines on the two sides of the island. Males of silvestris from populations from the north and east side of the island ("Hilo-side") display a novel morphological secondary sexual character. This is absent not only from south and west ("Kona-side") silvestris but also from heteroneura and from the three closely related species endemic to older adjacent islands. In view of the phylogenetic novelty of this evolutionary development, Hilo-side silvestris is judged to be derived from Kona-side rather than vice versa. The character in question involves the addition of about 25 large cilia to the dorsal surface of the tibia of the male. This portio of the leg is used in a very specific fashion to stimulate the female's abdomen during the courtship ritual. Studies of sexual behaviour of individuals drawn from various natural and laboratory populations of silvestris and its relatives have been carried out. Hybrid sterility and/or inviability is lacking in crosses both within and between populations of heterneura and silvestra. An interesting regularity has been widely observed; there is a positive correlation between the phylogenetic age of the population and the degree of discrimination by the female sex in mating. When this principle is applied to silvestris populations, the Kona-side populations of Hualalai volcano are judged to be the oldest in the species. As expected, Hilo-side populations with the novel bristle character appear to be newly-derived...

Animals↗
PubMed1996

Polygenic control of a mating signal in Drosophila.

Recent findings show that traits which influence speciation in the melanogaster subgroup of Drosophila can be determined by relatively few loci and/ or be sex-linked. Using backcrosses between D. simulans and D. mauritiana, we show that an acoustic mating signal which plays an important role in courtship (the interpulse interval of the 'lovesong') has a polygenic determination. There is no evidence of single genes of large effect, a disproportionate contribution of the sex chromosome or epistasis. The probability of finding single genes with a large effect on sexual isolation may vary with the mode of signalling involved.

Animals↗
PubMed2004

Unusually dynamic sex roles in a fish.

Sex roles are typically thought of as being fixed for a given species. In most animals males compete for females, whereas the females are more reluctant to mate. Therefore sexual selection usually acts most strongly on males. This is explained by males having a higher potential reproductive rate than females, leading to more males being sexually active (a male-biased operational sex ratio). However, what determines sex roles and the strength of sexual selection is a controversial and much debated question. In this large-scale field study, we show a striking temporal plasticity in the mating competition of a fish (two-spotted goby, Gobiusculus flavescens). Over the short breeding season fierce male-male competition and intensive courtship behaviour in males were replaced by female-female competition and actively courting females. Hence, sex role reversal occurred rapidly. This is the first time that a shift in sex roles has been shown in a vertebrate. The shift might be explained by a large decline in male abundance, strongly skewing the sex ratio towards females. Notably, the sex role reversal did not occur at an equal operational sex ratio, contrary to established sex role theory.

Animals↗
PubMed2006

Repeated morphological evolution through cis-regulatory changes in a pleiotropic gene.

The independent evolution of morphological similarities is widespread. For simple traits, such as overall body colour, repeated transitions by means of mutations in the same gene may be common. However, for more complex traits, the possible genetic paths may be more numerous; the molecular mechanisms underlying their independent origins and the extent to which they are constrained to follow certain genetic paths are largely unknown. Here we show that a male wing pigmentation pattern involved in courtship display has been gained and lost multiple times in a Drosophila clade. Each of the cases we have analysed (two gains and two losses) involved regulatory changes at the pleiotropic pigmentation gene yellow. Losses involved the parallel inactivation of the same cis-regulatory element (CRE), with changes at a few nucleotides sufficient to account for the functional divergence of one element between two sibling species. Surprisingly, two independent gains of wing spots resulted from the co-option of distinct ancestral CREs. These results demonstrate how the functional diversification of the modular CREs of pleiotropic genes contributes to evolutionary novelty and the independent evolution of morphological similarities.

Animals↗
PubMed2002

Nucleotide variation at the no-on-transient A gene in Drosophila littoralis.

The no-on-transient A (nonA) gene encodes a putative RNA-binding protein, and mutations in this gene are known to affect vision, male courtship song and viability in Drosophila melanogaster. Here we have sequenced the coding region of the nonA gene of Drosophila littoralis and compared it with those of Drosophila virilis and D. melanogaster. All portions of nonA appeared to be conserved between D. littoralis and D. virilis, while the 5' region of the gene of these two species showed high divergence from that of a more distantly-related species, D. melanogaster. The same was true for the glycine repeat regions. No significant deviation from neutrality was observed in the analysis of intraspecific nucleotide variation in 5' or 3' region of the nonA gene in D. littoralis population. Also, comparison of D. littoralis sequences with homologous sequence of D. virilis suggests that the gene is evolving neutrally in D. virilis group. Divergence of the 5' regions between D. virilis group species and D. melanogaster could be a result of positive selection, but this finding is obscured by the long divergence time of the species groups.

Animals↗
PubMed2005

Population structure and host-plant specialization in two Scaptodrosophila flower-breeding species.

In contrast to phytophagous insect species, little attention has been paid to the possibility of host races in the Drosophilidae, although flower-breeding species, where courtship and mating take place on the flowers, are likely candidates. Two species of Scaptodrosophila, S. hibisci and S. aclinata, are restricted to flowers of Hibiscus species (section Furcaria), and the Furcaria specialization likely predated the separation of S. hibisci and S. aclinata. In all, 20 microsatellite loci were analysed in nine populations of S. hibisci and five of S. aclinata. For two pairs of S. hibisci populations in close proximity, but breeding on different Hibiscus species, differentiation between the populations of each of these pairs was similar to that between the populations that were from the same Hibiscus species, but geographically distant, suggesting the early stages of host-race formation. Genetic variability was significantly less in S. aclinata than in S. hibisci, suggesting greater drift effects in the former. However, of 253 alleles detected, 82 were present in both species, 160 in S. hibisci only and 11 in S. aclinata only, indicating that S. aclinata was derived from S. hibisci, following a strong bottleneck at the time of separation--possibly 40,000 years BP. Analyses and interpretation of Hardy-Weinberg equilibrium and F statistics needed to account for null alleles known to be present at eight loci in S. hibisci, and possibly present at other loci. The results emphasize the need for caution in studies where the presence of null alleles is inferred only from population data.

Animals↗
PubMed2006

The quantitative genetic basis of polyandry in the parasitoid wasp, Nasonia vitripennis.

Understanding the evolution of female multiple mating (polyandry) is crucial for understanding sexual selection and sexual conflict. Despite this interest, little is known about its genetic basis or whether genetics influences the evolutionary origin or maintenance of polyandry. Here, we explore the quantitative genetic basis of polyandry in the parasitoid wasp Nasonia vitripennis, a species in which female re-mating has been observed to evolve in the laboratory. We performed a quantitative genetic experiment on a recently collected population of wasps. We found low heritabilities of female polyandry (re-mating frequency after 18 h), low heritability of courtship duration and a slightly higher heritability of copulation duration. However, the coefficients of additive genetic variance for these traits were all reasonably large (CV(A)>7.0). We also found considerable dam effects for all traits after controlling for common environment, suggesting either dominance or maternal effects. Our work adds to the evidence that nonadditive genetic effects may influence the evolution of mating behaviour in Nasonia vitripennis, and the evolution of polyandry more generally.

Animals↗
PubMed1997

Fusion of splicing factor genes PSF and NonO (p54nrb) to the TFE3 gene in papillary renal cell carcinoma.

We demonstrate that the cytogenetically defined translocation t(X;1)(p11.2;p34) observed in papillary renal cell carcinomas results in the fusion of the splicing factor gene PSF located at 1p34 to the TFE3 helix-loop-helix transcription factor gene at Xp11.2. In addition we define an X chromosome inversion inv(X)(p11.2;q12) that results in the fusion of the NonO (p54nrb) gene to TFE3. NonO (p54nrb), the human homologue of the Drosophila gene NonAdiss which controls the male courtship song, is closely related to PSF and also believed to be involved in RNA splicing. In each case the rearrangement results in the fusion of almost the entire splicing factor protein to the TFE3 DNA-binding domain. These observations suggest the possibility of intriguing links between the processes of RNA splicing, DNA transcription and oncogenesis.

Adolescent↗
PubMed2000

Spinal cord injury and partner relationships.

INTRODUCTION: Among the many issues confronting a newly spinal cord injured (SCI) person are apprehension about the potential impact of the acquired disability on present or future intimate relationships. OBJECTIVE: To summarize the research regarding partner relationships and SCI. METHOD: Medline, Psychlit and Cinahl database researches were undertaken. RESULTS: Several studies have focused on the issue of marital status before and after the onset of the injury. The results of the studies carried out on the prevalence of divorce are conflicting. Divorce rates have been reported to be anywhere from 8% to 48%. It appears that divorce rates tend to decline to the normal rate for the general population after the initial high risk period. Some studies have shown that marital status is a powerful predictor of independent-living outcome variables. Thus, marital stability is a concern in SCI care. The study investigating why able-bodied women might choose to marry men with a permanent physical disability, such as a SCI, showed a substantial overlap with existing models of courtship. It was also shown that a SCI person who strives to minimise the impact of the disability on a potential partner makes a more attractive candidate for a long-term relationship than an individual who has come to rely on others. CONCLUSION: Partner relationships seem to be affected by a SCI, although not as much as is widely believed. There are, however, problems interpreting the varying results of the studies due to culture differences, changes in family life in society in general and the different methodologies used. Systematic research that puts the patients' and partners' problems into perspective is necessary. Uniformity in measurement instruments would facilitate comparisons of studies.

Divorce↗
PubMed2002

Distribution of androgen receptor mRNA expression and immunoreactivity in the brain of the green anole lizard.

Male courtship and copulation are androgen dependent in the green anole lizard, and female receptivity can be facilitated by testosterone. However, only a few, and relatively large, regions in the brain have been implicated in the control of these behaviours. In situ hybridization and immunohistochemistry were therefore used to determine in detail where androgens are likely to act in the brains of breeding males and females. A 697-bp fragment of the anole androgen receptor (AR) was cloned from total RNA isolated from the kidney, which contains the highly androgen-sensitive renal sex segment. The cloned fragment spanned part of the C, the entire D, and part of the E domains, and shared a high degree of similarity with the AR of various species. 35S-labelled antisense and sense probes were generated from the 697-bp fragment for use in in situ hybridization, and the AR antibody PG-21 was used for immunohistochemistry. Both sexes consistently had AR mRNA expression and immunoreactivity in areas associated with vertebrate reproductive behaviours and in motor areas of the brainstem. Interestingly, the PG-21 antibody produced labelling in both the nucleus and cytoplasm, including neuronal processes. The distribution of mRNA and immunoreactivity were comparable in males and females, and the amount of labelling was generally similar, although slightly greater in females. The expression pattern of AR in this species supports the idea that distribution is highly conserved among vertebrates, but that it probably does not dictate behavioural differences between the sexes in anoles.

Amino Acid Sequence↗
PubMed1998

Inheritance of behavioural differences between two interfertile, sympatric species, Drosophila silvestris and D. heteroneura.

The Hawaiian fly species, Drosophila silvestris and D. heteroneura, are sympatric and interfertile but show strong behavioural isolation and major differences in male aggressive behaviour and the associated morphology. As a first step in elucidating the genetic control of the differences between these species, we examined the mating and aggressive behaviour of their reciprocal F1 hybrids. The latency to the first wing vibration and the latency to copulate did not differ significantly between the parental species. However, D. heteroneura females had a very low tendency to copulate with D. silvestris males, rarely mating during the observation period. The duration of copulation also differed significantly; same-species pairs of D. silvestris had copulations that lasted about 50% longer than those of same-species pairs of D. heteroneura. The hybrids were intermediate between the parental species for both the tendency to copulate with D. silvestris males and the duration of copulation, suggesting codominance or polygenic inheritance for those traits. The aggression traits that we scored were the leg posture and wing extension during early aggression, and the leg posture and head position during escalated aggression. The parental species showed clear differences for each of these traits. The F1 hybrids resembled one parent or the other, without showing intermediate values, suggesting single-gene dominance or threshold expression of many genes for those traits. None of the courtship or aggressive traits showed X-chromosomal effects, although the head shape of hybrids is influenced by genes on the X chromosome. It is difficult to reconcile the patterns of inheritance of aggressive behaviour and the lack of an X-chromosomal effect with the hypothesis that these traits are influenced by a coadapted gene complex.

Aggression↗