The effect of flash duration and flash shape on entrainment in Pteroptyx malaccae,a synchronic Southeast Asian firefly

Southeast Asian synchronic fireflies respond to stimulus flashes by phase-shifting their endogenous oscillator. This is called 'flash entrainment'. The releasers for entrainment were studied by changing stimulus flash shape and duration in Pteroptyx malaccae. Stimulus flash shapes and durations were synthesized digitally and delivered by a field-portable computer system. The computer also recorded male firefly flashes that were detected with a photometer. We found that the type of entrainment and its magnitude was influenced by the duration of the entrainment flash and by its shape.     

Computer simulation of firefly flash sequences.

A new method is proposed for measuring nonsteady flow rates when this flow is pulsatile in nature. This method involves the use of indicators and does not require direct access to the vessel carrying the fluid. No knowledge of the associated mathematics is required for its application. The investigator infuses indator into the vessel leading into a capillary or similar labyrinth at a time-varying rate such that the indicator concentration at the outflow from the labyrinth remains constant in time. When this condition at the outflow has been achieved, the pulsatile flow rate at the inflow is given simply as the ratio of the varying infusion rate to the constant outflow indicator concentration.     

Role of nitric oxide and mitochondria in control of firefly flash

In light-producing cells (photocytes) of the firefly light organ,mitochondria are clustered in the cell periphery, positionedbetween the tracheolar air supply and the oxygen-requiring bioluminescentreactants which are sequestered in more centrally-localizedperoxisomes. This relative positioning suggests that mitochondriacould control oxygen availability for the light reaction. Wehypothesized that active cellular respiration would make theinterior regions of the photocytes relatively hypoxic, and thatthe "on" signal for production of bioluminescence might dependon inhibition of mitochondrial oxygen consumption, which wouldallow delivered oxygen to pass through the peripheral mitochondrialzone to reach peroxisomes deep in the cell interior. We publishedrecently that exogenous NO induces bioluminescence in the intactfirefly; that NO mediates octopamine-induced bioluminescencein the dissected lantern, and that nitric oxide synthase isabundant in cells of the tracheolar system of the light organ.Additional experiments showed that nitric oxide gas (NO) inhibitsrespiration in isolated lantern mitochondria. Inhibition isreversed by bright light, and this inhibition is relieved whenthe light is turned off. Altogether, the results support theidea that NO triggers light production by reversible inhibitionof mitochondrial respiration in lantern cells, and probablyin tracheolar cells as well. The data also suggest that thelight of bioluminescence itself relieves NO inhibition thuscontributing to rapid on/off switching. While other mechanismsmay be in play, NO production that is directly related to neuralinput appears to have a key role in the oxygen gating that controlsflash communication signals.     

Spontaneous interchanges in females of Drosophila melanogaster

Summary Herein is described an attempts to establish chromosome pairing-interchange relationships in Drosophila melanogaster female. For this purpose, the formation of half-translocations was studied in XXY and XX females bearing compounds of the second pair of autosomes. With respect to XXY females, it was expected that the free Y chromosome would pair with these compounds and that half-translocations involving 2L would arise. In as much as compound chromosomes in XX females had no partner for pairing, the formation of half-translocations involving 2L was not expected.Half-translocations were registered in the F₁ from crosses of XX and XXY females to b j pr cn/T(Y;2)C males. The cross was designed to permit the detection of very rarely occurring non-homologue interchanges.Offspring number was 335 in XX females and 550 in XXY females. The majority of offspring consisted of individuals arisen from the spontaneous restitution of compounds and the formation of 2n egg cells. Based on phenotype, the offspring of XX females contained 4 individuals with half-translocations involving 2L; there were 48 such flies among the offspring of XXY females. As confirmed by progeny analysis, 38 half-translocations occurred in XXY females and none in XX females. Of the 31 spontaneous interchanges in XXY females 28 were recorded between the Y and the left compound, one between the Y and the right compound, and one between the X and the left compound. Non-homologue interchanges were of oogonial origin judging by the fact that individuals with half-translocations arose in clusters. Unlike Y — left compound interchanges, the interchanges between autosomal compounds seem to be of meiotic origin.     

Kinetics of the light flash of the living firefly: a supramolecular process.

The light intensity vs. time curve of the light flash of the living firefly has been measured. Unlike the purified firefly enzyme system in aqueous solution, the living system does not show light decay conforming to a double exponential time curve, to simple first or second order decay, or to solid-state Elovich kinetics. Light decay of the living flash does show linearity in a probit vs. square root of time plot, which may indicate a reaction rate-limited by cooperative interactions of a biological phase transition. The observation that the kinetics of the firefly light system differ in the living cell from those in the purified system suggests that in the living system supramolecular factors control the rate of the reaction.     

Spontaneous aneuploidy level in blood cells of fertile females

In this study, we presented results of molecular cytogenetic assay of blood cells of fertile women of reproductive age. Cultivated and uncultivated cells and two sets of FISH probes with direct and indirect labeling were used. The middle level of aneuploidy for four chromosomes and statistical limits for aneuploidy detection were estimated. Aneuploidy determined with direct multicolor FISH in cultivated lymphocytes varied from 0.1 to 1.3%. The middle level of aneuploidy for all four chromosomes (13, 18, 21, and X) was 1.39%. The limit of mutation detection was 3.4%. We found differences in results with direct and indirect labeling. It was shown that the cultivation process influenced the level of aneuploidy. The absolute error in FISH technique was 0.13% and the relative error was 4.08%.     

Flash communication between the sexes of the firefly, Photuris lucicrescens

ABSTRACT. The courtship signal of the male firefly, Photuris lucicrescens Barber (Coleoptera, Lampyridae), is a brilliant crescendo flash which grows in intensity, reaches a peak and abruptly terminates. It was found to be triggered by a long neural burst from the brain. Males and females produce weak, twinkling flashes which induce male crescendo flashes. Female responses were triggered by a slowly rising intensity, and female response latency is therefore variable. Male and female P.lucicrescens fireflies produce two different types of flashes and both these flashes play an integral part in their courtship communication.     

Geographic differences in flash intervals and pre-mating isolation between populations of the Genji firefly, Luciola cruciata

Abstract.  1. Two types of Genji firefly, Luciola cruciata , have been recognised on the basis of the inter-flash interval.
2. The fast-flash and slow-flash type fireflies, distributed in the western and eastern parts of Japan, exhibit a 2- and 4-s interval of bioluminescence flash, respectively. In addition, an intermediate-flash type is found on the boundary between these two regions.
3. The differences in the responses of the males of four field populations to different intervals of artificial flashes were examined.
4. The results revealed that in the Aomori and Sendai populations (slow-flash type), a significantly larger number of males approached the 4- and 5-s flash intervals than approached the 2- and 3-s intervals of artificial flashes. On the other hand, in the Ohtsu population (fast-flash type), a significantly larger number of males approached the 2- and 3-s flash intervals than the 4- and 5-s intervals of artificial flashes. The Inuyama population (intermediate-flash type) did not show any particular preferences to flash intervals.
5. This study shows that in firefly populations, geographic variation in flash pattern can cause some degree of pre-mating isolation between populations.     

Variation in the flash pattern of the firefly,Photuris versicolor quadrifulgens (Coleoptera: Lampyridae)

We sampled a population of signalingPhoturis versicolor quadrifulgens fireflies to quantify the variation in flash patterns emitted by males. Males produced five distinct flash patterns during their mate-searching flights. Four of the patterns consisted of two to five equal-intensity pulses and the fifth pattern type was a flicker, a group of rapid modulations in intensity. We found that the proportions of each pattern remained relatively constant from night to night throughout the season. The different flash patterns produced varied significantly with time of night; patterns having fewer pulses occurred earlier in the evening. Local density, an estimate of competition, did not significantly correlate with flash pattern type. On consecutive emissions, individuals changed their flash types with a mean probability of 0.12 (over all males), and they usually switched between patterns differing by a single pulse (from a two- to a three-pulse pattern, from a three- to a two-pulse pattern, etc.). The nightly temporal changes in flash patterns may be related to tradeoffs between female availability and energetic costs of signaling or the changes may be related to increased predation risk from visual predators. Photuris versicolor quadrifulgens was originally described by Barber (1951) as a subspecies ofP. versicolor. The genusPhoturis is currently under revision by Dr. James E. Lloyd, and this firefly will be given species status.     

Urethane as an inhibitor of the firefly light reaction

A study has been made to test the hypothesis that general anesthetics such as urethane are able to inhibit light from a firefly reaction mixture. Urethane was found to reduce light emission in a dose-dependent manner, the minimal effective concentration being about 20 mM. Dixon plots gave a Ki value in the range of 175 to 215 mM. Lineweaver-Burk plots showed that urethane increases the apparent Km for ATP and reduces Vmax for the reaction. This is taken to mean that urethane acts as both a competitive and non-competitive inhibitor of the firefly light reaction (mixed-type inhibition).     

Exoskeleton anomalies in taiga tick females from populations of the Asian part of Russia

Geographic variation of exoskeleton anomalies in females of the taiga tick Ixodes persulcatus Schulze, 1930 is described in populations of the Asian part of Russia. The total material examined comprised 3872 females collected by the flagging method from vegetation in the Far Eastern, Siberian, and Ural Federal Districts of Russia. Exoskeleton anomalies were found in all the populations studied, the “shagreen skin” anomaly of the scutum being prevalent in all the localities. Anomalies were significantly more frequent (63.4 ± 3.39%) in females collected north of 55°N than in those collected in more southern localities of the Siberian Federal District (33.1 ± 3.43%). At the same time, the frequency of anomalies was lower (24.4 ± 1.93%) in females from the Far Eastern Federal District than in specimens from territories with an extreme continental climate. The variation in the females’ exoskeleton structure observed in the Asian part of Russia may reflect the natural phenogeographic variability rather than result from anthropogenic impact.     

The nearly complete mitogenome of the Southeast Asian firefly Pteroptyx tener (Coleoptera: Lampyridae)

Molecular Biology Reports - The estuarine firefly, Pteroptyx tener, aggregates in the thousands in mangrove trees lining tidal rivers in Southeast Asia where they engage one another in a nocturnal,...     

Only pollinator fig wasps have males that collaborate to release their females from figs of an Asian fig tree

Male insects rarely collaborate with each other, but pollinator fig wasps (Hymenoptera: Agaonidae) are said to be an exception. Immature fig wasps feed on galled ovules located inside figs, the inflorescences of Ficus species (Moraceae). After mating, adult pollinator males chew communal exit-holes that allow mated females (which are often also their siblings) to escape. Figs also support non-pollinating fig wasps (NPFWs), some of which produce exit-holes independently. We determined whether collaboration between pollinator males (Kradibia tentacularis from Ficus montana) was necessary for the release of their females, and used the relationship between male numbers and likelihood of success to measure the extent of cooperation during exit-hole production. These attributes were then compared with those of an NPFW (Sycoscapter sp.) from the same host plant. Pollinators were more abundant than NPFW, but their more female-biased sex ratio meant male pollinator densities were only slightly higher. Individual males of both species could produce an exit-hole. Single males of the NPFW were just as successful as single male pollinators, but only male pollinators cooperated effectively, becoming more successful as their numbers increased. The lack of cooperation among NPFW may be linked to their earlier period of intense inter-male aggression.     

2-S-cysteinylhydroquinone is an intermediate for the firefly luciferin biosynthesis that occurs in the pupal stage of the Japanese firefly,Luciola lateralis

Firefly luciferin is a natural product that is well-known to function as the substrate of the bioluminescence reaction in luminous beetles. However, the details of the biosynthetic system are still unclear. In this study, we showed by LC-MS/MS analysis that stable isotope-labeled 2-S-cysteinylhydroquinone was incorporated into firefly luciferin in living firefly specimens. Comparison of the incorporation efficiency among the developmental stages suggested that firefly luciferin is biosynthesized predominantly in the pupal stage. We also accomplished the in vitro biosynthesis of firefly luciferin using 2-S-cysteinylhydroquinone and the crude buffer extract of firefly pupae, suggesting the presence of a biosynthetic enzyme in the pupal extract.     

Chemically modified firefly luciferase is an efficient source of near-infrared light

Bioluminescence and bioluminescence resonance energy transfer (BRET) are two naturally occurring light emission phenomena that have been adapted to a wide variety of important research applications including in vivo imaging and enzyme assays. The luciferase enzyme from the North American firefly, which produces yellow-green light, is a key component of many of these applications. Recognizing the heightened interest in the potential of near-infrared (nIR) light to improve these technologies, we have demonstrated that spectral emissions with maxima of 705 and 783 nm can be efficiently produced by a firefly luciferase variant covalently labeled with nIR fluorescent dyes. In one case, an outstanding BRET ratio of 34.0 was achieved emphasizing the importance of selective labeling with fluorescent dyes and the efficiency provided by the intramolecular BRET process. Additionally, we constructed a biotinylated fusion protein that similarly produced nIR light. This novel material was immobilized on solid supports containing streptavidin, demonstrating, in principle, that it may be used for receptor-based imaging. Also, the matrix-bound labeled fusion protein was used to measure factor Xa activity at physiological concentrations in blood. We believe this to be the first report of bright nIR light sources produced by chemical modification of a beetle luciferase.     

Inter-sexual multimodal communication during mating in wild geladas: the leading role of females

Female primates can emit vocalizations associated with mating that can function as honest signals of fertility. Here, we investigated the role of mating calls and visual signals in female geladas (Theropithecus gelada). Because females have a central role in the gelada society and seem to solicit sexual interactions, we answered whether they emit vocalizations in conjunction with gazing to increase mating success probability. Before and during copulations, females can emit pre-copulation calls and copulation calls. For the first time, we identified a new female vocalization emitted at the final stage of copulations (end-copulation call), possibly marking the occurrence of ejaculation. We found that longer pre-copulation call sequences were followed by both prolonged copulations and the presence of end-copulation calls, thus suggesting that females use pre-copulation calls to ensure successful copula completion. Moreover, we found that different combinations of female vocal types and gazing had different effects on male vocal behavior and motivation to complete the copula. The analysis of the vocal and visual signals revealed a complex inter-sexual multimodal chattering with the leading role of females in the signal exchange. Such chattering, led by females, modulates male sexual arousal, thus increasing the probability of the copula success.