Elevating bioavailable iron levels in mitochondria suppresses the defective phenotypes caused by PINK1 loss-of-function in Drosophila melanogaster.

Parkinson's disease (PD) is the second most common progressive neurodegenerative disease, which is characterized by the loss of dopaminergic neurons in the substantia nigra pars compacta (SNpc). Iron deposit was found in the SNpc of PD patients and animal models, however, the mechanisms involved in disturbed iron metabolism remain unknown. Identifying the relationship between iron metabolism and PD is important for finding new therapeutic strategies. In this study, we found that transgenic overexpression (OE) of Drosophila mitoferrin (dmfrn) or knockdown of Fer3HCH significantly mitigated the reduced mitochondrial aconitase activity, abnormal wing posture, flight deficits and mitochondrial morphology defects associated with PINK1 loss-of-function (LOF). Further work demonstrated that dmfrn OE or Fer3HCH knockdown significantly rescued the impaired mitochondrial respiration in PINK1 LOF flies, indicating that dmfrn or Fer3HCH may rescue PINK1 LOF phenotypes through elevating mitochondrial bioavailable iron levels to promote mitochondrial respiration.

Bidirectional Regulation of Sleep and Synapse Pruning after Neural Injury.

Following acute neural injury, severed axons undergo programmed Wallerian degeneration over several following days. While sleep has been linked with synaptic reorganization under other conditions, the role of sleep in responses to neural injuries remains poorly understood. To study the relationship between sleep and neural injury responses, we examined Drosophila melanogaster following the removal of antennae or other sensory tissues. Daytime sleep is elevated after antennal or wing injury, but sleep returns to baseline levels within 24 h after injury. Similar increases in sleep are not observed when olfactory receptor neurons are silenced or when other sensory organs are severed, suggesting that increased sleep after injury is not attributed to sensory deprivation, nociception, or generalized inflammatory responses. Neuroprotective disruptions of the E3 ubiquitin ligase highwire and c-Jun N-terminal kinase basket in olfactory receptor neurons weaken the sleep-promoting effects of antennal injury, suggesting that post-injury sleep may be influenced by the clearance of damaged neurons. Finally, we show that pre-synaptic active zones are preferentially removed from severed axons within hours after injury and that depriving recently injured flies of sleep slows the removal of both active zones and damaged axons. These data support a bidirectional interaction between sleep and synapse pruning after antennal injury: locally increasing the need to clear neural debris is associated with increased sleep, which is required for efficient active zone removal after injury.

A Drosophila Model of Essential Tremor.

Essential Tremor (ET) is one of the most common neurological diseases, with an estimated 7 million affected individuals in the US; the pathophysiology of the disorder is poorly understood. Recently, we identified a mutation (KCNS2 (Kv9.2), c.1137 T > A, p.(D379E) in an electrically silent voltage-gated K+ channel α-subunit, Kv9.2, in a family with ET, that modulates the activity of Kv2 channels. We have produced transgenic Drosophila lines that express either the human wild type Kv9.2 (hKv9.2) or the ET causing mutant Kv9.2 (hKv9.2-D379E) subunit in all neurons. We show that the hKv9.2 subunit modulates activity of endogenous Drosophila K+ channel Shab. The mutant hKv9.2-D379E subunit showed significantly higher levels of Shab inactivation and a higher frequency of spontaneous firing rate consistent with neuronal hyperexcitibility. We also observed behavioral manifestations of nervous system dysfunction including effects on night time activity and sleep. This functional data further supports the pathogenicity of the KCNS2 (p.D379E) mutation, consistent with our prior observations including co-segregation with ET in a family, a likely pathogenic change in the channel pore domain and absence from population databases. The Drosophila hKv9.2 transgenic model recapitulates several features of ET and may be employed to advance our understanding of ET disease pathogenesis.

The Strategy to Survive Primary Malaria Infection: An Experimental Study on Behavioural Changes in Parasitized Birds.

Avian malaria parasites (Haemosporida, Plasmodium) are of cosmopolitan distribution, and they have a significant impact on vertebrate host fitness. Experimental studies show that high parasitemia often develops during primary malaria infections. However, field studies only occasionally reveal high parasitemia in free-living birds sampled using the traditional methods of mist-netting or trapping, and light chronic infections predominate. The reason for this discrepancy between field observation and experimental data remains insufficiently understood. Since mist-netting is a passive capture method, two main parameters determine its success in sampling infected birds in wildlife, i. e. the presence of parasitized birds at a study site and their mobility. In other words, the trapping probability depends on the survival rate of birds and their locomotor activity during infection. Here we test (1) the mortality rate of wild birds infected with Plasmodium relictum (the lineage pSGS1), (2) the changes in their behaviour during presence of an aerial predator, and (3) the changes in their locomotor activity at the stage of high primary parasitemia.We show that some behavioural features which might affect a bird's survival during a predator attack (time of reaction, speed of flush flight and take off angle) did not change significantly during primary infection. However, the locomotor activity of infected birds was almost halved compared to control (non-infected) birds during the peak of parasitemia. We report (1) the markedly reduced mobility and (2) the 20% mortality rate caused by P. relictum and conclude that these factors are responsible for the underrepresentation of birds in mist nets and traps during the stage of high primary parasitemia in wildlife. This study indicates that the widespread parasite, P. relictum (pSGS1) influences the behaviour of birds during primary parasitemia. Experimental studies combined with field observations are needed to better understand the mechanisms of pathogenicity of avian malaria parasites and their influence on bird populations.

[Non-infectious unilateral wing lameness of pigeons, so called "Schieffliegersyndrom". First clinical and pathological results]. / Belastungsbedingte, nichtinfektiöse unilaterale Buggelenksarthropathie der Brieftauben ("Schieffliegersyndrom"). Erste Resultate zu klinischen Symptomen und pathologischen Veränderungen.

OBJECTIVE: After medium- and long-distance flights and following the first training units of the year, a unilateral injuring of the shoulder joint is observed in racing pigeons. The objective of the study was to discuss the pathogenesis and aetiology of the damage. MATERIAL AND METHODS: In 35 pigeons suffering from unilateral wing lameness, the affected shoulder joints were examined microbiologically and histopathologically. Additionally, both shoulder joints of 12 affected pigeons were examined pathologically and histopathologically. RESULTS: Joint capsule, articular cartilage, tendons and bone structures displayed pathological changes. CONCLUSION: The non-infectious unilateral wing lameness of pigeons appears to be a stress-induced mechanical damage of the shoulder joint. The different structures of the joint are over-extended by the physical/mechanical influences during longer flights.

Identification of a novel Afipia species isolated from an Indian flying fox.

An old world fruit bat Pteropus giganteus, held in captivity and suffering from necrosis of its wing digits, failed to respond to antibiotic therapy and succumbed to the infection. Samples submitted to the National Centre for Foreign Animal Disease were tested for viral infection. Vero E6 cells exhibited minor but unique cytopathic effects on second blind passage, and full CPE by passage four. Utilizing an unbiased random amplification technique from cell culture supernatant, we identified a bacterium belonging to the Bradyrhizobiaceae. Purification of cell culture supernatant on TY media revealed a slow growing bacterial isolate. In this study using electron microscopy, 16S rRNA gene analysis and whole genome sequencing, we identify a novel bacterial species associated with the site of infection belonging to the genus Afipia. This genus of bacteria is very diverse, with only a limited number of species characterized. Afipia felis, previously described as the etiological agent to cause cat scratch disease, and Afipia septicemium, most recently shown to cause disease in humans, highlight the potential for members of this genus to form a branch of opportunistic pathogens within the Bradyrhizobiaceae. Increased utilization of next generation sequencing and genomics will aid in classifying additional members of this intriguing bacterial genera.

A new torsion control mechanism induced by blood circulation in dragonfly wings.

A new mechanism to generate the torque of flapping dragonfly wings is disclosed in this paper. The concept is inspired by blood circulation in insect wings. The blood flowing in veins induces Coriolis forces in the flapping wings. The Coriolis forces acting on veins are of opposite directions when blood flows in and out. The opposite Coriolis forces generate torsional moment to the wing, especially in the leading-edge part. To estimate the time-varying torque induced by the blood circulation, a simplified U-tube model is designed. A three-dimensional finite element model of the wing is developed to analyze the dynamic behaviors under this torque. The dragonfly wing is in favor of torsional deformation because the corrugated structure is of high flexural rigidity in the spanwise direction but is of low torsional rigidity in the chordwise direction. In both the downstroke and upstroke, the twist of the leading-edge part causes the sections to camber spontaneously. Such a kind of deformation is found to be of great importance to improve aerodynamic efficiency. In addition, it also compensates for the disadvantageous bending deformation caused by air pressure in flapping flight. These results are important for better understanding of the multifunctional structures of dragonfly wings and may give some inspiration to the bionics of flapping-wing micro air vehicles (FMAVs).

Flight and seizure motor patterns in Drosophila mutants: simultaneous acoustic and electrophysiological recordings of wing beats and flight muscle activity.

Abstract Tethered flies allow studies of biomechanics and electrophysiology of flight control. We performed microelectrode recordings of spikes in an indirect flight muscle (the dorsal longitudinal muscle, DLMa) coupled with acoustic analysis of wing beat frequency (WBF) via microphone signals. Simultaneous electrophysiological recording of direct and indirect flight muscles has been technically challenging; however, the WBF is thought to reflect in a one-to-one relationship with spiking activity in a subset of direct flight muscles, including muscle m1b. Therefore, our approach enables systematic mutational analysis for changes in temporal features of electrical activity of motor neurons innervating subsets of direct and indirect flight muscles. Here, we report the consequences of specific ion channel disruptions on the spiking activity of myogenic DLMs (firing at ∼5 Hz) and the corresponding WBF (∼200 Hz). We examined mutants of the genes enconding: 1) voltage-gated Ca(2+) channels (cacophony, cac), 2) Ca(2+)-activated K(+) channels (slowpoke, slo), and 3) voltage-gated K(+) channels (Shaker, Sh) and their auxiliary subunits (Hyperkinetic, Hk and quiver, qvr). We found flight initiation in response to an air puff was severely disrupted in both cac and slo mutants. However, once initiated, slo flight was largely unaltered, whereas cac displayed disrupted DLM firing rates and WBF. Sh, Hk, and qvr mutants were able to maintain normal DLM firing rates, despite increased WBF. Notably, defects in the auxiliary subunits encoded by Hk and qvr could lead to distinct consequences, that is, disrupted DLM firing rhythmicity, not observed in Sh. Our mutant analysis of direct and indirect flight muscle activities indicates that the two motor activity patterns may be independently modified by specific ion channel mutations, and that this approach can be extended to other dipteran species and additional motor programs, such as electroconvulsive stimulation-induced seizures.

Pattern reorganization occurs independently of cell division during Drosophila wing disc regeneration in situ.

One of the most intriguing problems in developmental biology is how an organism can replace missing organs or portions of its body after injury. This capacity, known as regeneration, is conserved across different phyla. The imaginal discs of Drosophila melanogaster provide a particularly well-characterized model for analyzing regeneration. We have developed a unique method to study organ regeneration under physiological conditions using the imaginal discs of Drosophila. Using this method, we revisited different aspects of organ regeneration. The results presented in this report suggest that during the initial stages of regeneration, different processes occur, including wound healing, a temporary loss of markers of cell-fate commitment, and pattern reorganization. We present evidence indicating that all of these processes occur even when cell division has been arrested. Our data also suggested that Wingless is not required during the early stages of disc regeneration.

Inhibition of TTR aggregation-induced cell death--a new role for serum amyloid P component.

BACKGROUND: Serum amyloid P component (SAP) is a glycoprotein that is universally found associated with different types of amyloid deposits. It has been suggested that it stabilizes amyloid fibrils and therefore protects them from proteolytic degradation. METHODOLOGY/PRINCIPAL FINDINGS: In this paper, we show that SAP binds not only to mature amyloid fibrils but also to early aggregates of amyloidogenic mutants of the plasma protein transthyretin (TTR). It does not inhibit fibril formation of TTR mutants, which spontaneously form amyloid in vitro at physiological pH. We found that SAP prevents cell death induced by mutant TTR, while several other molecules that are also known to decorate amyloid fibrils do not have such effect. Using a Drosophila model for TTR-associated amyloidosis, we found a new role for SAP as a protective factor in inhibition of TTR-induced toxicity. Overexpression of mutated TTR leads to a neurological phenotype with changes in wing posture. SAP-transgenic flies were crossed with mutated TTR-expressing flies and the results clearly confirmed a protective effect of SAP on TTR-induced phenotype, with an almost complete reduction in abnormal wing posture. Furthermore, we found in vivo that binding of SAP to mutated TTR counteracts the otherwise detrimental effects of aggregation of amyloidogenic TTR on retinal structure. CONCLUSIONS/SIGNIFICANCE: Together, these two approaches firmly establish the protective effect of SAP on TTR-induced cell death and degenerative phenotypes, and suggest a novel role for SAP through which the toxicity of early amyloidogenic aggregates is attenuated.

Wing pathology of white-nose syndrome in bats suggests life-threatening disruption of physiology.

White-nose syndrome (WNS) is causing unprecedented declines in several species of North American bats. The characteristic lesions of WNS are caused by the fungus Geomyces destructans, which erodes and replaces the living skin of bats while they hibernate. It is unknown how this infection kills the bats. We review here the unique physiological importance of wings to hibernating bats in relation to the damage caused by G. destructans and propose that mortality is caused by catastrophic disruption of wing-dependent physiological functions. Mechanisms of disease associated with G. destructans seem specific to hibernating bats and are most analogous to disease caused by chytrid fungus in amphibians.

Site directed mutagenesis of Drosophila flightin disrupts phosphorylation and impairs flight muscle structure and mechanics.

Flightin is a myosin rod binding protein that in Drosophila melanogaster is expressed exclusively in the asynchronous indirect flight muscles (IFM). Hyperphosphorylation of flightin coincides with the completion of myofibril assembly and precedes the emergence of flight competency in young adults. To investigate the role of flightin phosphorylation in vivo we generated three flightin null (fln(0)) Drosophila strains that express a mutant flightin transgene with two (Thr158, Ser 162), three (Ser139, Ser141, Ser145) or all five potential phosphorylation sites mutated to alanines. These amino acid substitutions result in lower than normal levels of flightin accumulation and transgenic strains that are unable to beat their wings. On two dimensional gels of IFM proteins, the transgenic strain with five mutant sites (fln(5STA)) is devoid of all phosphovariants, the transgenic strain with two mutant sites (fln(2TSA)) expresses only the two least acidic of the nine phosphovariants, and the transgenic strain with three mutant sites (fln(3SA)) expresses all nine phosphovariants, as the wild-type strain. These results suggest that phosphorylation of Thr158 and/or Ser162 is necessary for subsequent phosphorylation of other sites. All three transgenic strains show normal, albeit long, IFM sarcomeres in newly eclosed adults. In contrast, sarcomeres in fully mature fln(5STA) and fln(2TSA) adults show extensive breakdown while those in fln(3SA) are not as disordered. The fiber hypercontraction phenotype that characterizes fln(0) is fully evident in fln(5STA) and fln(2TSA) but partially rescued in fln(3SA). Mechanics on skinned fibers from newly eclosed flies show alterations in viscous modulus for fln(5STA) and fln(2TSA) that result in a significant reduction in oscillatory power output. Expression of fln(5STA) and fln(2TSA), but not fln(3SA), in a wild-type (fln(+)/fln(+)) background resulted in a dominant negative effect manifested as flight impairments and hypercontracted IFM fibers. Our studies indicate that Thr158 and/or Ser162 are (is) indispensable for flightin function and suggest that phosphorylation of one or both residues fulfills an essential role in IFM structural stability and mechanics.

Training in microvascular surgery using a chicken wing artery.

OBJECTIVE: Microarterial anastomosis is now seldom performed for treatment of atherosclerotic occlusive cerebrovascular disease. However, a small but significant number of procedures still require this technique. When a surgeon's clinical experience is limited, regular practice is required to maintain and improve surgical skills. The present training system involves passage from suturing of synthetic materials (such as Silastic tubes) to practice with experimental living animals or cadavers. However, these methods are neither convenient nor practical for daily exercises and rehearsals. I present a unique training exercise for microarterial anastomosis, using a chicken wing artery. METHODS: A brachial artery can be extracted from a chicken wing. The artery is 5 to 6 cm long and measures approximately 1 mm in diameter. The artery can be used to practice end-to-end, end-to-side, or side-to-side anastomosis under the microscope. RESULTS: Several advantages are noted: the materials are cheap, convenient to manage, and easy to obtain, and neither specific facilities to maintain living animals nor anesthesia is needed. Moreover, the diameter and structure of the material are identical to those of human cortical vessels, making the rehearsal quite similar to the actual surgical experience. CONCLUSION: This exercise is useful not only for young surgeons who wish to learn microsurgical techniques but also for more experienced surgeons who need to maintain or improve their skills.

Bone hyperemia precedes disuse-induced intracortical bone resorption.

An in vivo model was used to determine whether bone hyperemia precedes increased intracortical porosity induced by disuse. Twenty-four adult male roosters (age 1 yr) were randomly assigned to intact-control, 7-days-sham-surgery, 7-days-disuse, and 14-days-disuse groups. Disuse was achieved by isolating the left ulna diaphysis from physical loading via parallel metaphyseal osteotomies. The right ulna served as an intact contralateral control. Colored microspheres were used to assess middiaphyseal bone blood flow. Bone blood flow was symmetric between the left and right ulnae of the intact-control and sham-surgery groups. After 7 days of disuse, median (+/-95% confidence interval) standardized blood flow was significantly elevated compared with the contralateral bone (6.5 +/- 5.2 vs. 1.0 +/- 0.8 ml x min-1 x 100 g-1; P = 0.03). After 14 days of disuse, blood flow was also elevated but to a lesser extent. Intracortical porosity in the sham-surgery and 7-days-disuse bones was not elevated compared with intact-control bones. At 14 days of disuse, the area of intracortical porosity was significantly elevated compared with intact control bones (0.015 +/- 0.02 vs. 0. 002 +/- 0.002 mm2; P = 0.03). We conclude that disuse induces bone hyperemia before an increase in intracortical porosity. The potential interaction between bone vasoregulation and bone cell dynamics remains to be studied.

Drosophila myb is required for the G2/M transition and maintenance of diploidy.

The myb proto-oncogenes are thought to have a role in the cell division cycle. We have examined this possibility by genetic analysis in Drosophila melanogaster, which possesses a single myb gene. We have described previously two temperature-sensitive, recessive lethal mutants in Drosophila myb (Dm myb). The phenotypes of these mutants revealed a requirement for myb in diverse cellular lineages throughout the course of Drosophila development. We now report a cellular explanation for these findings by showing that Dm myb is required for both mitosis and prevention of endoreduplication in wing cells. Myb apparently acts at or near the time of the G2/M transition. The two mutant alleles of Dm myb produce the same cellular phenotype, although the responsible mutations are located in different functional domains of the gene product. The mutant phenotype can be partially suppressed by ectopic expression of either cdc2 or string, two genes that are known to promote the transition from G2 to M. We conclude that Dm myb is required for completion of cell division and may serve two independent functions: promotion of mitosis, on the one hand, and prevention of endoreduplication when cells are arrested in G2, on the other.

Effects of caffeine on mating frequency and pre-copulation and copulation durations in Drosophila prosaltans.

Parameters of sexual behaviour were studied in Drosophila prosaltans treated with 2,500 micrograms/ml of caffeine per 1 ml of banana culture medium. The mating frequency and copulation duration were greater in control than in treated flies, while the pre-copulation duration was greater in treated flies than in controls. Statistical analysis showed that for the pre-copulation duration the difference was significant.

Brachial plexus injury in two red-tailed hawks (Buteo jamaicensis).

Two red-tailed hawks (Buteo jamaicensis), found near Deltaville, Virginia (USA), were evaluated because of inability to use a wing. Results of needle electromyographic studies of the affected wing muscles in both hawks were compatible with denervation. On euthanasia, one hawk had extensive axon and myelin loss with multifocal perivascular lymphocytic inflammation of its brachial plexus and radial nerve. Demyelination and axon loss in the dorsal white matter of the spinal cord on the affected side also were found at the origin of the brachial plexus. The other hawk's wing had not returned to functional status > 2 yr after injury.

An analysis of the integrity of the brachial motor unit in the dystrophic chick embryo.

In New Hampshire chickens, the primary clinical symptom of dystrophy is limitation of wing motility. Examination of the brachial-level motor unit in chick embryos homozygous for dystrophy reveals abnormalities in both muscular and neural components. Wing motility in these embryos is abnormal as early as six days, and there is a corresponding lack of differentiation of the pectoralis major muscle. The findings suggest that delayed development of brachial-level neuronal pathways is responsible for the decreased wing motility and early degeneration of the pectoral muscle.