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Air Sac
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Thomas B Kornberg – One of the best experts on this subject based on the ideXlab platform.
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myoblast cytonemes mediate wg signaling from the wing imaginal disc and delta notch signaling to the Air Sac primordium
eLife, 2015Co-Authors: Hai Huang, Thomas B KornbergAbstract:The flight muscles, dorsal Air Sacs, wing blades, and thoracic cuticle of the Drosophila adult function in concert, and their progenitor cells develop together in the wing imaginal disc. The wing disc orchestrates dorsal Air Sac development by producing decapentaplegic and fibroblast growth factor that travel via specific cytonemes in order to signal to the Air Sac primordium (ASP). Here, we report that cytonemes also link flight muscle progenitors (myoblasts) to disc cells and to the ASP, enabling myoblasts to relay signaling between the disc and the ASP. Frizzled (Fz)-containing myoblast cytonemes take up Wingless (Wg) from the disc, and Delta (Dl)-containing myoblast cytonemes contribute to Notch activation in the ASP. Wg signaling negatively regulates Dl expression in the myoblasts. These results reveal an essential role for cytonemes in Wg and Notch signaling and for a signal relay system in the myoblasts.
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myoblast cytonemes mediate wg signaling from the wing imaginal disc and delta notch signaling to the Air Sac primordium
eLife, 2015Co-Authors: Hai Huang, Thomas B KornbergAbstract:Fruit fly larvae undergo a remarkable physical transformation to become an adult fly. During this transformation, the tissues in the larvae change into the structures found in the adult. For example, the adult wings, flight muscles, and other structures needed for coordinated flight form from a pAir of disc-like tissues called the wing imaginal discs. For these structures to develop correctly, the cells in the wing imaginal discs need to receive coordinated instructions about what types of cells they need to become. Within the wing discs, finger-like projections called cytonemes link specific cells together to allow signal molecules to move between the cells; this controls the development of the wing disc itself as well as structures called dorsal Air Sacs, which supply oxygen to the flight muscles in the adult fly. However, it is not known if cytonemes allow the exchange of signal molecules between cells involved in the formation of other structures needed for flight. Here, Huang and Kornberg investigated the role of cytonemes in the development of the flight muscles in fruit flies. The experiments reveal that cells called myoblasts—which will later become the flight muscle cells—form two sets of cytonemes with other cells. One set connects the myoblasts to cells in the developing Air Sac, which allows a signal protein called Delta to signal from the myoblasts into the Air Sac cells. The other set of cytonemes connects the myoblasts to wing disc cells. This enables another signal molecule called Wingless, which is produced in wing disc cells, to move into the myoblasts and block the production of Delta. Huang and Kornberg’s findings reveal a new role for cytonemes in coordinating the development of the flight muscles and the dorsal Air Sacs. A future challenge will be to understand how individual cytonemes are able to connect to specific cells.
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regulation of drosophila matrix metalloprotease mmp2 is essential for wing imaginal disc trachea association and Air Sac tubulogenesis
Developmental Biology, 2009Co-Authors: Arjun Guha, Li Lin, Thomas B KornbergAbstract:The Drosophila Dorsal Air Sac Primordium (ASP) is a tracheal tube that grows toward Branchless FGF-expressing cells in the wing imaginal disc. We show that the ASP arises from a tracheal branch that invades the basal lamina of the disc to juxtapose directly with disc cells. We examined the role of matrix metalloproteases (Mmps), and found that reducing Mmp2 activity perturbed disc-trachea association, altered peritracheal distributions of collagen IV and Perlecan, misregulated ASP growth, and abrogated development of the dorsal Air Sacs. Whereas the function of the membrane-tethered Mmp2 in the ASP is non-cell autonomous we find that it may have distinct tissue-specific roles in the ASP and disc. These findings demonstrate a critical role for Mmp2 in tubulogenesis post-induction, and implicate Mmp2 in regulating dynamic and essential changes to the extracellular matrix.
P J Ponganis – One of the best experts on this subject based on the ideXlab platform.
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Cervical Air Sac oxygen profiles in diving emperor penguins: parabronchial ventilation and the respiratory oxygen store.
The Journal of Experimental Biology, 2020Co-Authors: Cassondra L. Williams, M Scadeng, Max F. Czapanskiy, Jason S. John, Judy St. Leger, P J PonganisAbstract:ABSTRACTSome marine birds and mammals can perform dives of extraordinary duration and depth. Such dive performance is dependent on many factors, including total body oxygen (O2) stores. For diving penguins, the respiratory system (Air Sacs and lungs) constitutes 30–50% of the total body O2 store. To better understand the role and mechanism of parabronchial ventilation and O2 utilization in penguins both on the surface and during the dive, we examined Air Sac partial pressures of O2 (PO2) in emperor penguins (Aptenodytes forsteri) equipped with backpack PO2 recorders. Cervical Air Sac PO2 values at rest were lower than in other birds, while the cervical Air Sac to posterior thoracic Air Sac PO2 difference was larger. Pre-dive cervical Air Sac PO2 values were often greater than those at rest, but had a wide range and were not significantly different from those at rest. The maximum respiratory O2 store and total body O2 stores calculated with representative anterior and posterior Air Sac PO2 data did not differ from prior estimates. The mean calculated anterior Air Sac O2 depletion rate for dives up to 11 min was approximately one-tenth that of the posterior Air Sacs. Low cervical Air Sac PO2 values at rest may be secondary to a low ratio of parabronchial ventilation to parabronchial blood O2 extraction. During dives, overlap of simultaneously recorded cervical and posterior thoracic Air Sac PO2 profiles supported the concept of maintenance of parabronchial ventilation during a dive by Air movement through the lungs.
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penguin lungs and Air Sacs implications for baroprotection oxygen stores and buoyancy
The Journal of Experimental Biology, 2015Co-Authors: P J Ponganis, J St Leger, M ScadengAbstract:ABSTRACT The anatomy and volume of the penguin respiratory system contribute significantly to pulmonary baroprotection, the body O 2 store, buoyancy and hence the overall diving physiology of penguins. Therefore, three-dimensional reconstructions from computerized tomographic (CT) scans of live penguins were utilized to measure lung volumes, Air Sac volumes, tracheobronchial volumes and total body volumes at different inflation pressures in three species with different dive capacities [Adelie ( Pygoscelis adeliae ), king ( Aptenodytes patagonicus ) and emperor ( A. forsteri ) penguins]. Lung volumes scaled to body mass according to published avian allometrics. Air Sac volumes at 30 cm H 2 O (2.94 kPa) inflation pressure, the assumed maximum volume possible prior to deep dives, were two to three times allometric Air Sac predictions and also two to three times previously determined end-of-dive total Air volumes. Although it is unknown whether penguins inhale to such high volumes prior to dives, these values were supported by (a) body density/buoyancy calculations, (b) prior Air volume measurements in free-diving ducks and (c) previous suggestions that penguins may exhale Air prior to the final portions of deep dives. Based upon Air capillary volumes, parabronchial volumes and tracheobronchial volumes estimated from the measured lung/Airway volumes and the only available morphometry study of a penguin lung, the presumed maximum Air Sac volumes resulted in Air Sac volume to Air capillary/parabronchial/tracheobronchial volume ratios that were not large enough to prevent barotrauma to the non-collapsing, rigid Air capillaries during the deepest dives of all three species, and during many routine dives of king and emperor penguins. We conclude that volume reduction of Airways and lung Air spaces, via compression, constriction or blood engorgement, must occur to provide pulmonary baroprotection at depth. It is also possible that relative Air capillary and parabronchial volumes are smaller in these deeper-diving species than in the spheniscid penguin of the morphometry study. If penguins do inhale to this maximum Air Sac volume prior to their deepest dives, the magnitude and distribution of the body O 2 store would change considerably. In emperor penguins, total body O 2 would increase by 75%, and the respiratory fraction would increase from 33% to 61%. We emphasize that the maximum pre-dive respiratory Air volume is still unknown in penguins. However, even lesser increases in Air Sac volume prior to a dive would still significantly increase the O 2 store. More refined evaluations of the respiratory O 2 store and baroprotective mechanisms in penguins await further investigation of species-specific lung morphometry, start-of-dive Air volumes and body buoyancy, and the possibility of Air exhalation during dives.
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Penguin lungs and Air Sacs: implications for baroprotection, oxygen stores and buoyancy.
The Journal of experimental biology, 2015Co-Authors: P J Ponganis, J St Leger, M ScadengAbstract:The anatomy and volume of the penguin respiratory system contribute significantly to pulmonary baroprotection, the body O2 store, buoyancy and hence the overall diving physiology of penguins. Therefore, three-dimensional reconstructions from computerized tomographic (CT) scans of live penguins were utilized to measure lung volumes, Air Sac volumes, tracheobronchial volumes and total body volumes at different inflation pressures in three species with different dive capacities [Adélie (Pygoscelis adeliae), king (Aptenodytes patagonicus) and emperor (A. forsteri) penguins]. Lung volumes scaled to body mass according to published avian allometrics. Air Sac volumes at 30 cm H2O (2.94 kPa) inflation pressure, the assumed maximum volume possible prior to deep dives, were two to three times allometric Air Sac predictions and also two to three times previously determined end-of-dive total Air volumes. Although it is unknown whether penguins inhale to such high volumes prior to dives, these values were supported by (a) body density/buoyancy calculations, (b) prior Air volume measurements in free-diving ducks and (c) previous suggestions that penguins may exhale Air prior to the final portions of deep dives. Based upon Air capillary volumes, parabronchial volumes and tracheobronchial volumes estimated from the measured lung/Airway volumes and the only available morphometry study of a penguin lung, the presumed maximum Air Sac volumes resulted in Air Sac volume to Air capillary/parabronchial/tracheobronchial volume ratios that were not large enough to prevent barotrauma to the non-collapsing, rigid Air capillaries during the deepest dives of all three species, and during many routine dives of king and emperor penguins. We conclude that volume reduction of Airways and lung Air spaces, via compression, constriction or blood engorgement, must occur to provide pulmonary baroprotection at depth. It is also possible that relative Air capillary and parabronchial volumes are smaller in these deeper-diving species than in the spheniscid penguin of the morphometry study. If penguins do inhale to this maximum Air Sac volume prior to their deepest dives, the magnitude and distribution of the body O2 store would change considerably. In emperor penguins, total body O2 would increase by 75%, and the respiratory fraction would increase from 33% to 61%. We emphasize that the maximum pre-dive respiratory Air volume is still unknown in penguins. However, even lesser increases in Air Sac volume prior to a dive would still significantly increase the O2 store. More refined evaluations of the respiratory O2 store and baroprotective mechanisms in penguins await further investigation of species-specific lung morphometry, start-of-dive Air volumes and body buoyancy, and the possibility of Air exhalation during dives.
Hai Huang – One of the best experts on this subject based on the ideXlab platform.
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myoblast cytonemes mediate wg signaling from the wing imaginal disc and delta notch signaling to the Air Sac primordium
eLife, 2015Co-Authors: Hai Huang, Thomas B KornbergAbstract:The flight muscles, dorsal Air Sacs, wing blades, and thoracic cuticle of the Drosophila adult function in concert, and their progenitor cells develop together in the wing imaginal disc. The wing disc orchestrates dorsal Air Sac development by producing decapentaplegic and fibroblast growth factor that travel via specific cytonemes in order to signal to the Air Sac primordium (ASP). Here, we report that cytonemes also link flight muscle progenitors (myoblasts) to disc cells and to the ASP, enabling myoblasts to relay signaling between the disc and the ASP. Frizzled (Fz)-containing myoblast cytonemes take up Wingless (Wg) from the disc, and Delta (Dl)-containing myoblast cytonemes contribute to Notch activation in the ASP. Wg signaling negatively regulates Dl expression in the myoblasts. These results reveal an essential role for cytonemes in Wg and Notch signaling and for a signal relay system in the myoblasts.
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myoblast cytonemes mediate wg signaling from the wing imaginal disc and delta notch signaling to the Air Sac primordium
eLife, 2015Co-Authors: Hai Huang, Thomas B KornbergAbstract:Fruit fly larvae undergo a remarkable physical transformation to become an adult fly. During this transformation, the tissues in the larvae change into the structures found in the adult. For example, the adult wings, flight muscles, and other structures needed for coordinated flight form from a pAir of disc-like tissues called the wing imaginal discs. For these structures to develop correctly, the cells in the wing imaginal discs need to receive coordinated instructions about what types of cells they need to become. Within the wing discs, finger-like projections called cytonemes link specific cells together to allow signal molecules to move between the cells; this controls the development of the wing disc itself as well as structures called dorsal Air Sacs, which supply oxygen to the flight muscles in the adult fly. However, it is not known if cytonemes allow the exchange of signal molecules between cells involved in the formation of other structures needed for flight. Here, Huang and Kornberg investigated the role of cytonemes in the development of the flight muscles in fruit flies. The experiments reveal that cells called myoblasts—which will later become the flight muscle cells—form two sets of cytonemes with other cells. One set connects the myoblasts to cells in the developing Air Sac, which allows a signal protein called Delta to signal from the myoblasts into the Air Sac cells. The other set of cytonemes connects the myoblasts to wing disc cells. This enables another signal molecule called Wingless, which is produced in wing disc cells, to move into the myoblasts and block the production of Delta. Huang and Kornberg’s findings reveal a new role for cytonemes in coordinating the development of the flight muscles and the dorsal Air Sacs. A future challenge will be to understand how individual cytonemes are able to connect to specific cells.
Franz Goller – One of the best experts on this subject based on the ideXlab platform.
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Motor control of sound frequency in birdsong involves the interaction between Air Sac pressure and labial tension.
Physical review. E Statistical nonlinear and soft matter physics, 2014Co-Authors: Rodrigo Gogui Alonso, Franz Goller, Gabriel B. MindlinAbstract:Frequency modumodulation is a salient acoustic feature of birdsong. Its control is usually attributed to the activity of syringeal muscles, which affect the tension of the labia responsible for sound production. We use experimental and theoretical tools to test the hypothesis that for birds producing tonal sounds such as domestic canaries (Serinus canaria), frequency modumodulation is determined by both the syringeal tension and the Air Sac pressure. For different models, we describe the structure of the isofrequency curves, which are sets of parameters leading to sounds presenting the same fundamental frequencies. We show how their shapes determine the relative roles of syringeal tension and Air Sac pressure in frequency modumodulation. Finally, we report experiments that allow us to unveil the features of the isofrequency curves.
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ventilation patterns of the songbird lung Air Sac system during different behaviors
The Journal of Experimental Biology, 2013Co-Authors: Rebecca Mackelprang, Franz GollerAbstract:Unidirectional, continuous Airflow through the avian lung is achieved through an elaborate Air Sac system with a sequential, posterior to anterior ventilation pattern. This classical model was established through various approaches spanning passively ventilated systems to mass spectrometry analysis of tracer gas flow into various Air Sacs during spontaneous breathing in restrained ducks. Information on flow patterns in other bird taxa is missing, and these techniques do not permit direct tests of whether the basic flow pattern can change during different behaviors. Here we use thermistors implanted into various locations of the respiratory system to detect small pulses of tracer gas (helium) to reconstruct Airflow patterns in quietly breathing and behaving (calling, wing flapping) songbirds (zebra finch and yellow-headed blackbird). The results illustrate that the basic pattern of Airflow in these two species is largely consistent with the model. However, two notable differences emerged. First, some tracer gas arrived in the anterior set of Air Sacs during the inspiration during which it was inhaled, suggesting a more rapid throughput through the lung than previously assumed. Second, differences in ventilation between the two anterior Air Sacs emerged during calling and wing flapping, indicating that adjustments in the flow pattern occur during dynamic behaviors. It is unclear whether this modulation in ventilation pattern is passive or active. This technique for studying ventilation patterns during dynamic behaviors proves useful for establishing detailed timing of Airflow and modulation of ventilation in the avian respiratory system.
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Ventilation patterns of the songbird lung/Air Sac system during different behaviors.
The Journal of experimental biology, 2013Co-Authors: Rebecca Mackelprang, Franz GollerAbstract:Unidirectional, continuous Airflow through the avian lung is achieved through an elaborate Air Sac system with a sequential, posterior to anterior ventilation pattern. This classical model was established through various approaches spanning passively ventilated systems to mass spectrometry analysis of tracer gas flow into various Air Sacs during spontaneous breathing in restrained ducks. Information on flow patterns in other bird taxa is missing, and these techniques do not permit direct tests of whether the basic flow pattern can change during different behaviors. Here we use thermistors implanted into various locations of the respiratory system to detect small pulses of tracer gas (helium) to reconstruct Airflow patterns in quietly breathing and behaving (calling, wing flapping) songbirds (zebra finch and yellow-headed blackbird). The results illustrate that the basic pattern of Airflow in these two species is largely consistent with the model. However, two notable differences emerged. First, some tracer gas arrived in the anterior set of Air Sacs during the inspiration during which it was inhaled, suggesting a more rapid throughput through the lung than previously assumed. Second, differences in ventilation between the two anterior Air Sacs emerged during calling and wing flapping, indicating that adjustments in the flow pattern occur during dynamic behaviors. It is unclear whether this modulation in ventilation pattern is passive or active. This technique for studying ventilation patterns during dynamic behaviors proves useful for establishing detailed timing of Airflow and modulation of ventilation in the avian respiratory system.
Ajay Srivastava – One of the best experts on this subject based on the ideXlab platform.
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JAK/STAT signaling is involved in Air Sac primordium development of Drosophila melanogaster.
FEBS letters, 2019Co-Authors: Nathan Powers, Ajay SrivastavaAbstract:The dorsal thoracic Air Sacs in fruit flies (Drosophila melanogaster) are functionally and developmentally comparable to human lungs. The progenitors of these structures, Air Sac primordia (ASPs), invasively propagate into wing imaginal disks, employing mechanisms similar to those that promote metastasis in malignant tumors. We investigated whether Janus kinase/signal transducer and activator of transcription JAK/STAT signaling plays a role in the directed morphogenesis of ASPs. We find that JAK/STAT signaling occurs in ASP tip cells and misexpression of core components in the JAK/STAT signaling cascade significantly impedes ASP development. We further identify Upd2 as an activating ligand for JAK/STAT activity in the ASP. Together, these data constitute a considerable step forward in understanding the role of JAK/STAT signaling in ASPs and similar structures in mammalian models.