Search

The species of the Strashilidae (strashilids) have been the most perplexing of fossil insects from the Jurassic period of Russia and China. They have been widely considered to be ectoparasites of pterosaurs or feathered dinosaurs, based on the putative presence of piercing and sucking mouthparts and hind tibio-basitarsal pincers purportedly used to fix onto the host's hairs or feathers. Both the supposed host and parasite occur in the Daohugou beds from the Middle Jurassic epoch of China (approximately 165 million years ago). Here we analyse the morphology of strashilids from the Daohugou beds, and reach markedly different conclusions; namely that strashilids are highly specialized flies (Diptera) bearing large membranous wings, with substantial sexual dimorphism of the hind legs and abdominal extensions. The idea that they belong to an extinct order is unsupported, and the lineage can be placed within the true flies. In terms of major morphological and inferred behavioural features, strashilids resemble the recent (extant) and relict members of the aquatic fly family Nymphomyiidae. Their ontogeny are distinguished by the persistence in adult males of larval abdominal respiratory gills, representing a unique case of paedomorphism among endopterygote insects. Adult strashilids were probably aquatic or amphibious, shedding their wings after emergence and mating in the water. [ABSTRACT FROM AUTHOR]

Animals from flies to humans are able to distinguish subtle gradations in temperature and show strong temperature preferences. Animals move to environments of optimal temperature and some manipulate the temperature of their surroundings, as humans do using clothing and shelter. Despite the ubiquitous influence of environmental temperature on animal behaviour, the neural circuits and strategies through which animals select a preferred temperature remain largely unknown. Here we identify a small set of warmth-activated anterior cell (AC) neurons located in the Drosophila brain, the function of which is critical for preferred temperature selection. AC neuron activation occurs just above the fly’s preferred temperature and depends on dTrpA1, an ion channel that functions as a molecular sensor of warmth. Flies that selectively express dTrpA1 in the AC neurons select normal temperatures, whereas flies in which dTrpA1 function is reduced or eliminated choose warmer temperatures. This internal warmth-sensing pathway promotes avoidance of slightly elevated temperatures and acts together with a distinct pathway for cold avoidance to set the fly’s preferred temperature. Thus, flies select a preferred temperature by using a thermal sensing pathway tuned to trigger avoidance of temperatures that deviate even slightly from the preferred temperature. This provides a potentially general strategy for robustly selecting a narrow temperature range optimal for survival. [ABSTRACT FROM AUTHOR]

Flexible goal-driven orientation requires that the position of a target be stored, especially in case the target moves out of sight. The capability to retain, recall and integrate such positional information into guiding behaviour has been summarized under the term spatial working memory. This kind of memory contains specific details of the presence that are not necessarily part of a long-term memory. Neurophysiological studies in primates indicate that sustained activity of neurons encodes the sensory information even though the object is no longer present. Furthermore they suggest that dopamine transmits the respective input to the prefrontal cortex, and simultaneous suppression by GABA spatially restricts this neuronal activity. Here we show that Drosophila melanogaster possesses a similar spatial memory during locomotion. Using a new detour setup, we show that flies can remember the position of an object for several seconds after it has been removed from their environment. In this setup, flies are temporarily lured away from the direction towards their hidden target, yet they are thereafter able to aim for their former target. Furthermore, we find that the GABAergic (stainable with antibodies against GABA) ring neurons of the ellipsoid body in the central brain are necessary and their plasticity is sufficient for a functional spatial orientation memory in flies. We also find that the protein kinase S6KII (ignorant) is required in a distinct subset of ring neurons to display this memory. Conditional expression of S6KII in these neurons only in adults can restore the loss of the orientation memory of the ignorant mutant. The S6KII signalling pathway therefore seems to be acutely required in the ring neurons for spatial orientation memory in flies. [ABSTRACT FROM AUTHOR]

Some morphological traits differ greatly between related species, but it is not clear whether diversity evolves through changes in the same genes and whether similar, independent (that is, convergent) changes occur by the same mechanism. Pigmentation in fruitflies presents an attractive opportunity to explore these issues because pigmentation patterns are diverse, similar patterns have arisen in independent clades, and numerous genes governing their formation have been identified in Drosophila melanogaster. Here we show that both evolutionary diversification and convergence can be due to evolution at the same locus, by comparing abdominal pigmentation and trichome patterns and the expression of Bric-à-brac2 (Bab2), which regulates both traits in D. melanogaster, in 13 species representing the major clades of the subfamily Drosophilinae. Modifications of Bab2 expression are frequently correlated with diverse pigmentation and trichome patterns that evolved independently in multiple lineages. In a few species, Bab2 expression is not correlated with changes in pigmentation but is correlated with a conserved pattern of trichomes, indicating that this locus can be circumvented to evolve new patterns when a correlated trait is under different constraints. [ABSTRACT FROM AUTHOR]

Classical population-genetics theory suggests that reproductive isolation will evolve fastest in small isolated populations. In contrast, recent theory suggests that divergence should occur fastest in larger allopatric populations. The rationale behind this is that sexual conflict, potentially the strongest driver of speciation, is greater in larger, higher-density populations. This idea is highly controversial and has little experimental support. Here we show, using replicate fly populations with varying levels of sexual conflict, that larger, more dense populations with more sexual conflict diverged to a greater degree than small populations with relaxed conflict. This result strongly suggests that speciation can occur rapidly in large populations through increased sexual conflict. [ABSTRACT FROM AUTHOR]

Reports that Ormia ochracea can behaviorally localize a salient sound source with a precision equal to that of humans. Measurement of auditory directional acuity; Details of how information is represented in the auditory system with hyperacute timecoding; Finding that nanoscale/microscale directional microphones patterned after the fly have the potential for highly accurate directional sensitivity, independent of their size; Mentions of coding strategy employed by the nervous system.

The article presents a reprint of the article "A receptor for subtle temperature changes," by François Rouyer and Abhishek Chatterjee, which appeared online on November 18, 2015. It discusses the study by C. Chen and colleagues which identified a receptor protein in flies' mechanosensory organs that acts as a temperature sensor that synchronizes the circadian clock with low-amplitude temperature cycles. It says that the protein was the Ionotropic Receptor 25a (IR25a).

Presents data from experiments which studied visual learning in the fly Drosophila melanogaster. Use of a flight simulator; How animals need to extract from sensory signals the actual predictors of salient events by separating them from non-predictive stimuli.

Examines homeotic gene expression and regulation in butterflies. Structure and expression of Precis coenia homeotic genes; Explanation of differences in abdominal limb formation in flies and butterflies; General implications for role homeotic genes in animal evolution.

States that the fate of the R7 photoreceptor cell in the Drosophila compound eye is established by a specific inductive interaction between the R8 photoreceptor neuron and the R7 precursor cell. The two cell-surface proteins that mediate this induction: the ligand, bride of sevenless2 (boss) and sevenless (sev), a tyrosine-kinase receptor; The unique structure of boss; Boss action as an antagonist of the sev receptor both in vivo and in vitro; More.

Reports that an enzyme that catalyses the light-dependent repair of (6-4)photoproduct exists in Drosophila melanogaster. Cyclobutane pyrimidine dimers (CPD); Pyrimidine (6-4) pyrimidone photoproducts ((6-4)photoproducts); Gel shift analysis showing two binding factors from Drosophila cells; Light-dependent modification of (6-4)photoproducts by the factor 1 fraction; Further details.

States that the subdivisions of the Drosophila embryo, called parasegments, are defined by the interface between cells expressing the homeoprotein Engrailed and cells expressing the secreted protein Wingless. Examination of the generation of cell-type diversity within parasegments by focusing on the choice of cell fate made by the engrailed (en)-expressing cells.

Presents the mapping and characterization of the `shibire' gene of `Drosophila.' Proposes that the `shibire' gene product and dynamin are cognate homologues since they have extensive similarity.

The article offers information on the collaboration of biologist David Anderson, computational-vision scientist Pietro Perona and neuroscientist Michael Dickinson, to develop a study about fly behaviour and machines that are capable of detecting and interpreting complex behaviours among humans. It mentions that the group have been creating tools that manipulate the fly nervous system and aims to understand neural researches that serve as a useful information to human studies. It affirms that such tools promise to be a boost for the field of fly behaviour and relates that the researchers hope that the concept will form the basis of an overall computational theory of behaviour.

The article offers information on the discovery of new memory system in Drosophila. The new memory system is responsible in choosing the direction to walk. A study was conducted on flies to determine the behaviour of a specific group of neurons, which enable flies to remember their original destination even if distracted en route by another landmark. The detour test reveals that the ring neurons mediate spatial orientation memory. The insect impaired of olfactory learning did not perform well. It is concluded that ring neurons participate in Drosophila.

Reports on the stalk-eyed fly and the genetic variation that underlies its response to environmental stress. Details regarding techniques of sexual selection, including sexual ornaments and evaluation methods; Differences between male and female expression; How the mate choice yields genetic benefits for offspring.

States that occasional long-distance dispersal may be important to the dynamics of an increasing spread of an inherited cytoplasmic incompatibility factor that reduces egg hatch in the California `Drosophila simulans.' Experimental methods; Results; Discussion.

Proposes a simple statistical test of the neutral protein evolution hypothesis based on a comparison of the number of amino-acid replacement substitutions to synonymous substitutions in the coding region of a locus. Compares DNA sequences of the coding region of the `Adh' locus in three species in the `Drosophila melanogaster' species subgroup.

Reports on the first known example of bidirectional cytoplasmic incompatibility (CI) between conspecific populations of `Drosophila simulans.' Also shows that the defects as early as the first cleavage division are associated with CI.

The article focuses on the study of Y. Grosjean and colleagues related on the ways odours from decaying vegetables and fruit serve as aphrodisiacs to male fruitflies. It says that the study found out that odours promote courtship behavior among males, which is evidenced through the aromatic compounds phenylacetic acid and phenylacetaldehyde. The study also reveals that IR84a-expressing olfactory neurons stimulate the glomerulus related to the courtship behaviour of male fruitflies.

The article focuses on the behaviour of neurons which facilitate the computation of visual motion in flies and vertebrates. It mentions the Hassenstein-Reichardt model wherein the photoreceptor signals are first split into on and off channels which carry both positive and negative components. Furthermore, the study made by M. Joesch and colleagues shows that the two types of monopolar cell in flies, such as L1 and L2, have overlapping but distinguishable roles in the detection of visual motion.

The article reports on the population genomics for fruit-flies. This paper focuses on the observations made in the activities of the fruit-fly. It includes a scientific observation on the characteristics of the species when starved. The community of starved fruit-flies having to fight over a food. Genetics Researchers from the North Carolina State University located in Raleigh, North Carolina has conducted this interesting experiment. They have observed a range of responses and behavior including the aggressiveness and the sharing by the pacifists.

The article presents the seeing ability of ancestral flies. The paper reveals that the flies, through a specific modification to their photoreceptor cells improve the resolution of their eyes. Research on the subject points put that the 'Spacemaker' protein is responsible for the opening of the rhabodemeres. In conclusion, the researchers state that by reprogramming the expression of the 'Spacemaker' the flies may have invented neutral superposition.

Examines a Hox protein that activates a cell-death-inducing gene in a fruitfly. Overview on Hox genes; How a transcription factor can generate the characteristics of a particular segment; Cell-death signal.

Discusses a study published in the April 5, 2001 issue of 'Nature' magazine that reveals the degree of precision with which the parasitoid fly Ormia ochracea can locate crickets from their songs, and which describes a neuronal mechanism that could underlie this behavior. Discussion of the interaural time difference and the interaural intensity difference in Ormia; Unique features of the tympana, or eardrums; Measurement of the neuronal response latency differences; Possible applications of the research.

Focuses on the use of a computational approach to explore the properties of real gene networks. Discussion of problems with web-like genetic systems; Development of the system using fruit fly embryos; Discussion of close ties between model and real data; Outlook for the future use of model. INSET: Making segments in Drosophila.

Reports on the anticipated release of the complete sequence of the fly Drosophila melanogaster genome. Annotation of 2.9 Mb of DNA surrounding the alcohol dehydrogenase; Attempts to produce a comprehensive set of gene disruptions in the fly.

States that an analysis of mutant fruitflies is providing a mechanism for rapid morphological change. The fossil record indicating a step-wise change in morphological characteristics; Rapid proliferation of cells; High degree of precision needed in specifying the fates of individual cells and their spatial relationships; Discovery of heat-shock proteins; Function of Hsp90; How signalling proteins form complex webs of molecular switches; Isolation of fruitflies with mutations in Hsp90.

Focuses on the homeotic genes or Hox genes, which select the developmental pathways followed by cells. The antenna-to-leg transformation of the dominant Antennapedia or Antp mutant flies; Interactions that determine the development of the antennal and leg primordia.

Focuses on the implications of the results of the comparative analysis of Ultrabithorax (Ubx) expression on fruitflies and butterflies by R.W. Warren and colleagues. Revision of perception concerning homeotic genes; E.B. Lewis' work on the genetics of the bithorax complex (BX-C) of Drosophila; Cell-type-specific actions of homeotic genes.

Discusses the genetics and molecular biology of the hedgehog, wingless, and decapentaplegic (dpp) genes in Drosophila fruit flies. Cooperation of the three genes to determine the position of the prospective distal tip of the Drosophila leg; Description of the gene action and mechanisms.

The article focuses on the study conducted by Shunsuke Ishii and colleagues at the RIKEN Tsukuba Institute in Japan regarding the effect on stress in the phosphorylation of the protein ATF2 of Drosophila.

The article offers information on the research of Christophe Daugeron and his colleagues at the National Museum of Natural History in Paris, France, theorizing that a Japanese male dance fly (Empis jaschhoforum) is using an enlarged leg two court females.

The article discusses the genus reassessment of Drosophila melanogaster fruitfly.

The article presents a study which relates that fruitflies recruit distinct neural circuits when being on a state of arousal. It mentions that the group of researchers headed by David Anderson found that flies with loss-of-function mutations in the dopamine receptor are easily shocked by air puffs. It affirms that when they restored normal functionality to the receptor, the puff-induced arousal dropped while the sleep level remain unchanged.

The article provides information on a study on the spatial memory of the flies conducted by a group of German researchers lead by Ronald Strauss of the Johannes Gutenberg University in Mainz, Germany. It mentions that the ability of the flies to choose how to navigate their surroundings depend on their capacity for short-term, spatial memory. Strauss and his colleagues built a virtual reality fly arena to investigate whether the flies have brain. The wings of the flies were clipped and they were surrounded by a water moat. The result of the study suggests that the capacity of the flies for short-term memory is comparable to that of humans.

The article presents information on research in the study of genes. Researchers have identified several genes in microbes that have no apparent genetic ancestry. It is informed that researchers have found a gene in Drosophila melanogaster hydra whose homologous sequences could not be traced. It is stated that gene mutations could not have obscured any related sequence in the hydra as homologous sequences are not found in a species that had diverged from the hydra about 13 million years ago, which is too recent for mutations to obscure the relationship sequence. The research is viewed to suggest that the hydra arose de novo. It is also stated that researchers have identified 16 de novo genes in flies which they say evolved from non-coding DNA.

The article reports on the enlisting of worms and flies by U.S. researchers to make sense of the instructions embedded in human genome. Geneticists are engaged in the pilot phase of a project called the ENCODE, an encyclopedia of deoxyribonucleic acid elements in 2003. A four-year $57 million project called the modENCODE will add roundworms. It is stated that by these organisms, scientists can have better understanding of the human genome data collected from ENCODE.

Conservation biologists are drawing up a comprehensive plan for the preservation of invertebrates- populous but overlooked inhabitants of the animal world. Many researchers are aware of the plight of invertebrates, but such organisms have struggled to gain a foothold in conservation agendas. For example, only 189 species of invertebrate are listed as threatened or endangered under the U.S. Endangered Species Act, less than 40 percent of all the animal species listed. And with very few additional species now being added to that list, the prospect of adding uncharismatic flies and worms seems to be remote.

Presents science-related news items, as of December 18, 2003. Distortion of the iconic shape of conifers by exposure to air pollution; Amnesia in aging flies; Behavior of chaotic systems.

Ageing (senescence) has never been demonstrated convincingly in any insect in the wild, where mean lifespans are probably much shorter than in the laboratory, and most evidence for senescence in other wild animals (such as mammals) is limited to their reduced survival with age. Here we show that ageing is detectable in wild populations of a very short-lived insect, the antler fly (Protopiophila litigata), and causes debilitating and costly effects that force a decline not only in survival probability, but also in the reproductive rate of males. Our findings argue against the possibility of a trade-off between fitness components, whereby survival may decline without senescence if investment in reproduction increases with age, and indicate that ageing rates are subject to intense selection in the wild. [ABSTRACT FROM AUTHOR]

Investigates the susceptibility of flies to pathogens. Reduction of the plant sugar by Leishmania major; Susceptibility of starvation-tolerant sandflies to Leishmania major; Prevalence of seasonal and incidental stress among insects.

Focuses on the selection of mating partners in the long-tailed dance fly Rhamphomyia longicauda. Preference of males to mate with females with swollen abdomens; Absence of significant relationship between egg maturity and the size of the inflated abdomen; Reliance of female dance flies on males for prey.

Reports that Ernest Hafen and colleagues have discovered that flies with mutations in a gene termed chico are less than half the normal size and there appears to be fewer of the cells. Defects attributed to decreased cell growth and proliferation rather than increased cell death; Information of the Chico protein.

Provides background and analysis of a paper which examines how the nervous system of the fly deduces motion in three-dimensional space at a given instant in time. The pattern of image motion that is experienced by the moving eye; The six degrees of movement for a flying insect; The paper by Krapp and Hengstenberg in the December 5, 1996 issue of `Nature.'