Fly Body Research Articles

The Carotenoid Composition of Larvae Feed Is Reflected in Adult House Fly (Musca domestica) Body.

Carotenoids are common and diverse organic compounds with various functional roles in animals. Except for certain aphids, mites, and gall midges, all animals only acquire necessary carotenoids through their diet. The house fly (Musca domestica) is a cosmopolitan pest insect that populates diverse habitats. Its larvae feed on organic substrates that may vary in carotenoid composition according to their specific content. We hypothesized that the carotenoid composition in the adult house fly's body would reflect the carotenoid composition in the larval feed. House fly larvae were reared on diets that differed in carotenoid composition. HPLC analysis of the emerging adult flies indicate that the carotenoid composition of adult house flies is related, but not identical, to the carotenoid composition in its natal substrate. These findings may be developed to help identify potential sources of house fly infestations. Also, it is recommended that rearing substrates of house fly larvae, used for animal feed, should be carefully considered.

MUSCA SPP. FLIES INFESTATION ON A PIG FARM IN THE CITY OF DENPASAR

The role of flies in spreading disease is as a mechanical vector and a biological vector. As a mechanical vector flies carry pathogenic agents through their limbs. The fly's body has many hairs, especially on its legs. The hairs on the legs contain a kind of adhesive liquid so that small objects stick easily. Diseases transmitted by flies depend on the species. This study aims to determine the fluctuations and differences in the number of Musca spp. in a different environment on a pig farm in Denpasar City. This type of research is an observational study. The sample for this study were Musca sp. flies in two pig farms in Denpasar City. Samples were taken every day for 4 weeks at 09.00 – 14.00. Data analysis used the Wilcoxon test. The results showed that the Musca spp. found in pig farms in Ubung Kaja Village, North Denpasar, as many as 358 pigs and in Sidakarya Village, South Denpasar, as many as 981 pigs. The population of flies on pig farms in Ubung Kaja Village, North Denpasar and Sidakarya Village, South Denpasar, during 4 weeks of observation, fluctuated with the highest decrease in the 4th week and while the increase occurred in the 2nd week in North Denpasar, while in South Denpasar there was an increase in the 2nd week. up to 3. Based on the results of the study, it can be concluded that the population of flies on pig farms in Ubung Kaja Village, North Denpasar and Sidakarya Village, South Denpasar, during 4 weeks of observation, fluctuated with an increase occurring in the 3rd week in North Denpasar, while in South Denpasar there was an increase in the 2nd to 2nd week. 3. There is no difference in the number of Musca spp. in a different environment on a pig farm in Denpasar City. From these results, it can be suggested that pig farms should further improve environmental sanitation in their pens and surroundings by disposing of waste in properly managed bins and implementing good biosecurity. The research can be continued by increasing the number of places studied at different seasons so that the fluctuations of flies in the rainy and dry seasons can be determined.

Monitoring of soil transmitted helminth (STH) Helminthiasis on school-age children in final garbage dump, Bantar Gebang, East Bekasi

The prevalence of helminthiasis in West Java is 13.9%, but there is no data on STH helminthiasis on school-age children in the final garbage dump (FGD), Bantar Gebang, East Bekasi, Indonesia. Therefore, it is necessary to monitor STH helminthiasis on school-age children living around FGD. This study aims to determine the description of helminthiasis on school-age children who live in the FGD Bantar Gebang, Indonesia. This type of research is descriptive quantitative with a cross-sectional design. The sample in this study consisted of 79 stool children aged 5-9 years, 5 g of fly vectors from wet, dry, and soil were taken from 36 locations around the FGD. STH examination on stool, flies, and soil samples was carried out using the native, Harada Mori, flotation, and sedimentation methods. All data were analyzed using a descriptive approach to determine the percentage of the incidence of STH. The results of this study, among others, from 79 children there were six (7.60%) children infected with STH with the genus or species Ascaris lumbricoides, hookworm, and Trichuris trichiura. As for the 18 points of soil extraction, there were 12 (66.7%) positive points containing hookworm larvae, while the flies found were more dominant in Musca domestica than Chrysomya sp. with worm parasites attached to the fly's body are Ascaris lumbricoides, Diphyllobothrium latum. Enterobius vermicularis, hookworm, Hymenolepis sp., Schistosoma sp., Trichuris trichiura. The conclusion of this study is percentage incidence of STH helminthiasis on school-age children living in FGD Bantar Gebang is 7.60% which is in the low category.

Drosophila pain sensitization and modulation unveiled by a novel pain model and analgesic drugs.

In mammals, pain is regulated by the combination of an ascending stimulating and descending inhibitory pain pathway. It remains an intriguing question whether such pain pathways are of ancient origin and conserved in invertebrates. Here we report a new Drosophila pain model and use it to elucidate the pain pathways present in flies. The model employs transgenic flies expressing the human capsaicin receptor TRPV1 in sensory nociceptor neurons, which innervate the whole fly body, including the mouth. Upon capsaicin sipping, the flies abruptly displayed pain-related behaviors such as running away, scurrying around, rubbing vigorously, and pulling at their mouth parts, suggesting that capsaicin stimulated nociceptors in the mouth via activating TRPV1. When reared on capsaicin-containing food, the animals died of starvation, demonstrating the degree of pain experienced. This death rate was reduced by treatment both with NSAIDs and gabapentin, analgesics that inhibit the sensitized ascending pain pathway, and with antidepressants, GABAergic agonists, and morphine, analgesics that strengthen the descending inhibitory pathway. Our results suggest Drosophila to possess intricate pain sensitization and modulation mechanisms similar to mammals, and we propose that this simple, non-invasive feeding assay has utility for high-throughput evaluation and screening of analgesic compounds.

Phenotypic analyses, protein localization, and bacteriostatic activity of Drosophila melanogaster transferrin-1

Transferrin-1 (Tsf1) is an extracellular insect protein with a high affinity for iron. The functions of Tsf1 are still poorly understood; however, Drosophila melanogaster Tsf1 has been shown to influence iron distribution in the fly body and to protect flies against some infections. The goal of this study was to better understand the physiological functions of Tsf1 in D. melanogaster by 1) investigating Tsf1 null phenotypes, 2) determining tissue-specific localization of Tsf1, 3) measuring the concentration of Tsf1 in hemolymph, 4) testing Tsf1 for bacteriostatic activity, and 5) evaluating the effect of metal and paraquat treatments on Tsf1 abundance. Flies lacking Tsf1 had more iron than wild-type flies in specialized midgut cells that take up iron from the diet; however, the absence of Tsf1 had no effect on the iron content of whole midguts, fat body, hemolymph, or heads. Thus, as previous studies have suggested, Tsf1 appears to have a minor role in iron transport. Tsf1 was abundant in hemolymph from larvae (0.4 μM), pupae (1.4 μM), adult females (4.4 μM) and adult males (22 μM). Apo-Tsf1 at 1 μM had bacteriostatic activity whereas holo-Tsf1 did not, suggesting that Tsf1 can inhibit microbial growth by sequestering iron in hemolymph and other extracellular environments. This hypothesis was supported by detection of secreted Tsf1 in tracheae, testes and seminal vesicles. Colocalization of Tsf1 with an endosome marker in oocytes suggested that Tsf1 may provide iron to developing eggs; however, eggs from mothers lacking Tsf1 had the same amount of iron as control eggs, and they hatched at a wild-type rate. Thus, the primary function of Tsf1 uptake by oocytes may be to defend against infection rather than to provide eggs with iron. In beetles, Tsf1 plays a role in protection against oxidative stress. In contrast, we found that flies lacking Tsf1 had a typical life span and greater resistance to paraquat-induced oxidative stress. In addition, Tsf1 abundance remained unchanged in response to ingestion of iron, cadmium or paraquat or to injection of iron. These results suggest that Tsf1 has a limited role in protection against oxidative stress in D. melanogaster.

Anti-obesity effects of Erythrina abyssinica stem bark extract in flies exposed to a high fat diet

BackgroundAn in vitro assay on Sigmoidin A from Erythrina abyssinica stem bark revealed its potency to inhibit pancreatic lipase. However, studies indicate activity of extract bioactive compounds in combination far exceed the favorable effects of each individual compound due to synergy and additive effects. In this study, we provide information on the effect of E. abyssinica stem bark extract in Drosophila melanogaster. The objective of the study was to determine the safety and effects of E. abyssinica stem bark extract on fly survival, body weight, triglycerides, sterol, total protein, and catalase activity of obese male D. melanogaster. MethodsObesity was induced by exposing D. melanogaster white mutant w1118 to coconut food for two weeks. Groups 1–3 were fed on coconut food + fenofibrate at 25 mM, 50 mM, and 75 mM. Groups 4–6 were fed on coconut food + E. abyssinica stem bark extract at concentrations of 2.5 g/ml, 5.0 g/ml, and 7.5 g/ml. The positive control was exposed to only coconut food while the negative control was on regular food. Fly survival observations were done for 15 days, while acute and chronic effects were done at 30 min and after 48 h respectively following treatment. Body mass, negative geotaxis, reducing power of the extract, triglycerides (TG/TP), sterol, total protein levels, and catalase activity were measured after 10 days of exposure to the experimental diets. ResultsFly survival changes were observed after 10 days and E. abyssinica stem bark extract had the strongest reducing power at 7.5 g/ml extract concentration. E. abyssinica stem bark extract reduced body mass, triglyceride levels (TG/TP), sterol levels, and modulated catalase activity at 7.5 g/ml extract concentration. Though the standard drug fenofibrate had the highest fat accumulation reduction potential, the extract at 7.5 g/ml was much safer in reducing fat accumulation in obese male D. melanogaster than other concentration used. ConclusionAntioxidants in E. abyssinica stem bark extract are responsible for the observed anti-obesity activity.

Gut Parasites of medical importance harboured by Musca domestica in Calabar, Nigeria.

Housefly (Musca domestica), because of its body structure, filthy and feeding habits, is reported to be capable of carrying a variety of microbes, including potential pathogens, over its body appendages. This study aimed to investigate M. domestica in Calabar for pathogenic gut parasites, determine its role in parasitic diseases transmission, make appropriate recommendations toward its management and effective control of the associated parasitic diseases, and hence promote the society health status. This was a cross-sectional study. A total of 300 M. domestica specimens (150 each from sanitary and insanitary areas, pooled in batches of five flies per pool) were used for the study. The parasites were detected from the spun deposits of fly body surface wash and gut contents using direct microscopy and formol-ether technique. Data were analyzed using Statistical Package for the Social Sciences (SPSS), version 21.0, and Chi-square test at a significant level of P < 0.05. Overall frequency of parasites detection was 46.7%, with helminths and protozoa showing similar frequency, 23.3% each. External body surface of flies recorded a statistically significant higher parasites frequency 76.7% than their gut contents 16.7% (P = 0.000). A statistically significant higher parasite detection rate was observed in the insanitary (63.3%) than in sanitary areas (30.0%) (P = 0.0114). The parasites detected in this study were Entamoeba histolytica/dispar 39.9%, hookworm (21.4%), Ascaris lumbricoides (17.9%), Trichuris trichiura (14.3%), and Giardia intestinalis (7.2%). This study has confirmed M. domestica in Calabar as a mechanical carrier of potential pathogenic gut parasites, especially in the insanitary areas, with E. histolytica/dispar being the most frequently encountered. Effective control of flies' population in the human and animal habitats and increased public awareness on their health hazards are recommended.

A viral mutualist employs posthatch transmission for vertical and horizontal spread among parasitoid wasps

Heritable symbionts display a wide variety of transmission strategies to travel from one insect generation to the next. Parasitoid wasps, one of the most diverse insect groups, maintain several heritable associations with viruses that are beneficial for wasp survival during their development as parasites of other insects. Most of these beneficial viral entities are strictly transmitted through the wasp germline as endogenous viral elements within wasp genomes. However, a beneficial poxvirus inherited by Diachasmimorpha longicaudata wasps, known as Diachasmimorpha longicaudata entomopoxvirus (DlEPV), is not integrated into the wasp genome and therefore may employ different tactics to infect future wasp generations. Here, we demonstrated that transmission of DlEPV is primarily dependent on parasitoid wasps, since viral transmission within fruit fly hosts of the wasps was limited to injection of the virus directly into the larval fly body cavity. Additionally, we uncovered a previously undocumented form of posthatch transmission for a mutualistic virus that entails external acquisition and localization of the virus within the adult wasp venom gland. We showed that this route is extremely effective for vertical and horizontal transmission of the virus within D. longicaudata wasps. Furthermore, the beneficial phenotype provided by DlEPV during parasitism was also transmitted with perfect efficiency, indicating an effective mode of symbiont spread to the advantage of infected wasps. These results provide insight into the transmission of beneficial viruses among insects and indicate that viruses can share features with cellular microbes during their evolutionary transitions into symbionts.

A fungal parasite selects against body size but not fluctuating asymmetry in Swiss subalpine yellow dung flies

Evidence for selective disadvantages of large body size remains scarce in general. Previous studies of the yellow dung fly Scathophaga stercoraria have demonstrated strong positive sexual and fecundity selection on male and female size. Nevertheless, the body size of flies from a Swiss study population has declined by ~10% 1993–2009. Given substantial heritability of body size, this negative evolutionary response of an evidently positively selected trait suggests important selective factors being missed. An episodic epidemic outbreak of the fungus Entomophthora scatophagae permitted assessment of natural selection exerted by this fatal parasite. Fungal infection varied over the season from ~50% in the cooler and more humid spring and autumn to almost 0% in summer. The probability of dying from fungal infection increased with adult fly body size. Females never laid any eggs after infection, so there was no fungus effect on female fecundity beyond its impact on mortality. Large males showed their typical mating advantage in the field, but this positive sexual selection was nullified by fungal infection. Mean fluctuating asymmetry of paired appendages (legs, wings) did not affect the viability, fecundity or mating success of yellow dung flies in the field. This study documents rare parasite-mediated disadvantages of large-sized flies in the field. Reduced ability to combat parasites such as Entomophthora may be an immunity cost of large body size in dung flies, although the hypothesized trade-off between fluctuating asymmetry, a presumed indicator of developmental instability and environmental stress, and immunocompetence was not found here.

Inducing different severities of traumatic brain injury in Drosophila using a piezoelectric actuator

Drosophila models have been instrumental in providing insights into molecular mechanisms of neurodegeneration, with wide application to human disease. The brain degeneration associated with traumatic brain injury (TBI) has been modeled in Drosophila using devices that inflict trauma on multiple parts of the fly body, including the head. However, the injuries produced by these models are not specific in location and are inconsistent between individual animals. We have recently developed a device that can be used to inflict controlled head injury to flies, resulting in physiological responses that are remarkably similar to those observed in humans with TBI. This protocol describes the construction, calibration and use of the Drosophila TBI (dTBI) device, a platform that employs a piezoelectric actuator to reproducibly deliver a force in order to briefly compress the fly head against a metal surface. The extent of head compression can be controlled through an electrical circuit, allowing the operator to set different levels of injury. The entire device can be assembled and calibrated in under a week. The device components and the necessary electrical tools are readily available and cost ~$800. The dTBI device can be used to harness the power of Drosophila genetics and perform large-scale genetic or pharmacological screens, using a 7-d post-injury survival curve to identify modifiers of injury.

Resilin matrix distribution, variability and function in Drosophila

BackgroundElasticity prevents fatigue of tissues that are extensively and repeatedly deformed. Resilin is a resilient and elastic extracellular protein matrix in joints and hinges of insects. For its mechanical properties, Resilin is extensively analysed and applied in biomaterial and biomedical sciences. However, there is only indirect evidence for Resilin distribution and function in an insect. Commonly, the presence of dityrosines that covalently link Resilin protein monomers (Pro-Resilin), which are responsible for its mechanical properties and fluoresce upon UV excitation, has been considered to reflect Resilin incidence.ResultsUsing a GFP-tagged Resilin version, we directly identify Resilin in pliable regions of the Drosophila body, some of which were not described before. Interestingly, the amounts of dityrosines are not proportional to the amounts of Resilin in different areas of the fly body, arguing that the mechanical properties of Resilin matrices vary according to their need. For a functional analysis of Resilin matrices, applying the RNA interference and Crispr/Cas9 techniques, we generated flies with reduced or eliminated Resilin function, respectively. We find that these flies are flightless but capable of locomotion and viable suggesting that other proteins may partially compensate for Resilin function. Indeed, localizations of the potentially elastic protein Cpr56F and Resilin occasionally coincide.ConclusionsThus, Resilin-matrices are composite in the way that varying amounts of different elastic proteins and dityrosinylation define material properties. Understanding the biology of Resilin will have an impact on Resilin-based biomaterial and biomedical sciences.

Spatially-resolved metabolic profiling of living Drosophila in neurodegenerative conditions using 1H magic angle spinning NMR

Drosophila flies are versatile animal models for the study of gene mutations in neuronal pathologies. Their small size allows performing in vivo Magic Angle Spinning (MAS) experiments to obtain high-resolution 1H nuclear magnetic resonance (NMR) spectra. Here, we use spatially-resolved 1H high-resolution MAS NMR to investigate in vivo metabolite contents in different segments of the fly body. A comparative study of metabolic changes was performed for three neurodegenerative disorders: two cell-specific neuronal and glial models of Huntington disease (HD) and a model of glutamate excitotoxicity. It is shown that these pathologies are characterized by specific and sometimes anatomically localized variations in metabolite concentrations. In two cases, the modifications of 1H MAS NMR spectra localized in fly heads were significant enough to allow the creation of a predictive model.

Microbial communities of the house fly Musca domestica vary with geographical location and habitat

House flies (Musca domestica) are widespread, synanthropic filth flies commonly found on decaying matter, garbage, and feces as well as human food. They have been shown to vector microbes, including clinically relevant pathogens. Previous studies have demonstrated that house flies carry a complex and variable prokaryotic microbiota, but the main drivers underlying this variability and the influence of habitat on the microbiota remain understudied. Moreover, the differences between the external and internal microbiota and the eukaryotic components have not been examined. To obtain a comprehensive view of the fly microbiota and its environmental drivers, we sampled over 400 flies from two geographically distinct countries (Belgium and Rwanda) and three different environments—farms, homes, and hospitals. Both the internal as well as external microbiota of the house flies were studied, using amplicon sequencing targeting both bacteria and fungi. Results show that the house fly’s internal bacterial community is very diverse yet relatively consistent across geographic location and habitat, dominated by genera Staphylococcus and Weissella. The external bacterial community, however, varies with geographic location and habitat. The fly fungal microbiota carries a distinct signature correlating with the country of sampling, with order Capnodiales and genus Wallemia dominating Belgian flies and genus Cladosporium dominating Rwandan fly samples. Together, our results reveal an intricate country-specific pattern for fungal communities, a relatively stable internal bacterial microbiota and a variable external bacterial microbiota that depends on geographical location and habitat. These findings suggest that vectoring of a wide spectrum of environmental microbes occurs principally through the external fly body surface, while the internal microbiome is likely more limited by fly physiology.

Environmental filtering of body size and darker coloration in pollinator communities indicate thermal restrictions on bees, but not flies, at high elevations.

BackgroundBees and flies are the two most dominant pollinator taxa in mountain environments of the Southwest USA. Communities of both taxa change dramatically along elevation gradients. We examined whether bee and fly traits would also change along elevation gradients and if so, do they change in a predictable way related to a decrease in temperature as elevation increases.MethodsWe used insect body size and darkness traits as proxies for energetic requirements and indicators of cold tolerance in order to assess patterns of bee and fly community trait differences along an elevation gradient. We examined 1,922 individuals of bees and flies sampled along an elevation gradient ranging from 2,400 meters to 3,200 meters and from 9.6 °C to 5.2 °C mean annual temperature. We examined bees and flies separately using community weighted means (site-level trait values weighted by species abundance) and estimates of environmental filtering (quantified as the inverse of the standardized range of trait values).ResultsBees and flies exhibited two somewhat distinct patterns; (1) Community weighted mean body volume and darkness of bees increased sharply at the highest elevation, and the intensity of environmental filtering also increased with elevation. This was due to both a change among bee populations within a species as well as species replacement at the highest elevation. (2) Community weighted mean body volume and darkness of flies also increased moderately with increasing elevation, but did not exhibit patterns of significant environmental filtering. In fact, the intensity of environmental filtering as indicated by the range of fly body volume weakened with elevation.ConclusionThe increase in filter intensity at high elevations exhibited by bees suggests a significant limitation on the breadth of viable functional strategies for coping with extreme cold, at least within this regional species pool. Flies, on the other hand, do not appear to be limited by high elevations, indicating that the shift from bee to fly dominance at high elevations may be due, at least in part, to greater environmental constraints on bee adaptation to colder environments.

Coriolis and centrifugal forces drive haltere deformations and influence spike timing.

The halteres of flies are mechanosensory organs that serve a crucial role in the control of agile flight, providing sensory input for rapid course corrections to perturbations. Derived from hind wings, halteres are actively flapped and are thus subject to a variety of inertial forces as the fly undergoes complex flight trajectories. Previous analyses of halteres modelled them as a point mass, showing that Coriolis forces lead to subtle deflections orthogonal to the plane of flapping. By design, these models could not consider the effects of force gradients associated with a mass distribution, nor could they reveal three-dimensional spatio-temporal patterns of strain that result from those forces. In addition, diversity in the geometry of halteres, such as shape and asymmetries, could not be simply modelled with a point mass on a massless rod. To study the effects of mass distributions and asymmetries, we examine the haltere subject to both flapping and body rotations using three-dimensional finite-element simulations. We focus on a set of simplified geometries, in which we vary the stalk and bulb shape. We find that haltere mass distribution gives rise to two unreported deformation modes: (i) halteres twist with a magnitude that strongly depends on stalk and bulb geometry and (ii) halteres with an asymmetric mass distribution experience out-of-plane bending due to centrifugal forces, independent of body rotation. Since local strains at the base of the haltere drive deformations of mechanosensory neurons, we combined measured neural encoding mechanisms with our structural analyses to predict the spatial and temporal patterns of neural activity. This activity depends on both the flapping and rotation dynamics, and we show how the timing of neural activity is a viable mechanism for rotation-rate encoding. Our results provide new insights in haltere dynamics and show the viability for timing-based encoding of fly body rotations by halteres.

Assessment of microalgae as a new feeding additive for fruit fly Drosophila melanogaster

Animal food wastes are a concern due to the large amounts of commercial food required for model animals during the biological and biomedical research. Searching for sustainable food alternatives with negligible physiological effects on animals is critical to solve or reduce this challenge. Microalgae have been demonstrated to be suitable for both human consumption and animal feed. In this study, the possibility of using Chlorella vulgaris and Senedesmus obliquus as a feed replacement to Drosophila melanogaster, one of the fly models commonly used in biomedical studies, was investigated. Characteristics including the fly locomotor activity, motor pattern, feeding behavior, lifespan and body weight were assessed. Results showed that compared to control, the flies fed on 80% microalga (80-flies) in the total weight (w/w) had the double increased apparent step size, while both 60-flies and 80-flies exhibited longer travel distances (60%: 27.77 ± 1.99 cm; 80%: 31.50 ± 3.70 cm) most likely due to the starvation and varied serotonin levels in flies fed on high percentages microalgae. Subsequently, 40-flies exhibited less optimal growth performance with decreased body weights (0.51 ± 0.006 mg vs 0.60 ± 0.005 mg for control) and shorter mean lifespan (36 days vs 55.8 days for control. However, 20-flies showed no statistical differences in all parameters tested with respect to control flies, indicating that 20% microalgae treatment did not greatly change the primary food component such as carbohydrate which might play a critical role in fly performance. Therefore, the inclusion of 20% microalgae could be an alternative to fly standard food without compromising fly physiological performance.

Triacylglycerol Metabolism in Drosophila melanogaster.

Triacylglycerol (TAG) is the most important caloric source with respect to energy homeostasis in animals. In addition to its evolutionarily conserved importance as an energy source, TAG turnover is crucial to the metabolism of structural and signaling lipids. These neutral lipids are also key players in development and disease. Here, we review the metabolism of TAG in the Drosophila model system. Recently, the fruit fly has attracted renewed attention in research due to the unique experimental approaches it affords in studying the tissue-autonomous and interorgan regulation of lipid metabolism in vivo Following an overview of the systemic control of fly body fat stores, we will cover lipid anabolic, enzymatic, and regulatory processes, which begin with the dietary lipid breakdown and de novo lipogenesis that results in lipid droplet storage. Next, we focus on lipolytic processes, which mobilize storage TAG to make it metabolically accessible as either an energy source or as a building block for biosynthesis of other lipid classes. Since the buildup and breakdown of fat involves various organs, we highlight avenues of lipid transport, which are at the heart of functional integration of organismic lipid metabolism. Finally, we draw attention to some "missing links" in basic neutral lipid metabolism and conclude with a perspective on how fly research can be exploited to study functional metabolic roles of diverse lipids.

Two-Exponential Models of Gene Expression Patterns for Noisy Experimental Data.

Spatial pattern formation of the primary anterior-posterior morphogenetic gradient of the transcription factor Bicoid (Bcd) has been studied experimentally and computationally for many years. Bcd specifies positional information for the downstream segmentation genes, affecting the fly body plan. More recently, a number of researchers have focused on the patterning dynamics of the underlying bcd messenger RNA (mRNA) gradient, which is translated into Bcd protein. New, more accurate techniques for visualizing bcd mRNA need to be combined with quantitative signal extraction techniques to reconstruct the bcd mRNA distribution. Here, we present a robust technique for quantifying gradients with a two-exponential model. This approach (1) has natural, biologically relevant parameters and (2) is invariant to linear transformations of the data arising due to variation in experimental conditions (e.g., microscope settings, nonspecific background signal). This allows us to quantify bcd mRNA gradient variability from embryo to embryo (important for studying the robustness of developmental regulatory networks); sort out atypical gradients; and classify embryos to developmental stage by quantitative gradient parameters.

Survival and localization of African swine fever virus in stable flies (Stomoxys calcitrans) after feeding on viremic blood using a membrane feeder

Since 2014, African swine fever virus (ASFV) has been spreading within Eastern Europe. Within affected regions, the virus has infected some farms with high biosecurity and a marked seasonality of outbreaks in domestic pigs has been observed. ASFV transmission from stable flies, Stomoxys calcitrans, has previously been shown both mechanically and via ingestion of whole flies. Hence, blood-feeding flies may offer one explanation for the introductions into high biosecurity farms and for the observed seasonality. The aim of this study was to further elucidate the potential role of stable flies in ASFV transmission. Different parts of flies were analyzed for the presence of viral DNA and infectious virus at different time points following in vitro feeding of the flies on blood from an ASFV-infected pig.Using qPCR, ASFV DNA was detectable in mouth parts of flies for at least 12 h and remained in head and body samples from the flies for up to three days following feeding. Infectious virus was detected in fly body samples prepared at 3 h and 12 h after feeding.The presence of infectious ASFV in stable flies following feeding on viremic blood means that such flies are capable of transporting infectious virus. The detection of ASFV DNA in the flies for up to three days following feeding suggests that qPCR analysis of blood-feeding flies during ASFV outbreaks could be a useful method to elucidate the role of these flies in ASFV transmission under field conditions.

Neural Coding: Bumps on the Move

By meticulously deconstructing the Drosophila head-direction neural circuit, two recent studies have revealed the mechanism of how the fly's body rotations are translated into a continuously updated internal compass representation.