A review of the hexapod tracheal system with a focus on the apterygote groups

Water exchange between insects and their environment via the vapour phase includes influx and efflux components. The pressure cycle theory postulates that insects (and some other arthropods) can regulate the relative rates of influx and efflux of water vapour by modulating hydrostatic pressures at a vapour-liquid interface by compressing or expanding a sealed, gas-filled cavity. Some such cavities, like the tracheal system, could be compressed by elevated pressure in all or part of the haemocoele. Others, perhaps including the muscular rectum of flea prepupae, could be compressed by intrinsic muscles. Maddrell Insect Physiol . 8, 199 (1971)) suggested a pressure cycle mechanism of this kind to account for rectal uptake of water vapour in Thermobia but did not find it compatible with quantitative information then available. Newer evidence conforms better with the proposed mechanism. Cyclical pressure changes are of widespread occurrence in insects and have sometimes been shown to depend on water status. Evidence is reviewed for the role of the tracheal system as an avenue for net exchange of water between the insect and its environment. Because water and respiratory gases share common pathways, most published findings fail to distinguish between the conventional view that the tracheal system has evolved as a site for distribution and exchange of respiratory gases and that any water exchange occurring in it is generally incidental and nonadaptive, and the theory proposed here. The pressure cycle theory offers a supplementary explanation not incompatible with evidence so far available. The relative importance of water economy and respiratory exchange in the functioning of compressible cavities such as the tracheal system remains to be explored. Some further implications of the pressure cycle theory are discussed. Consideration is given to the possible involvement of vapour-phase transport in the internal redistribution of water within the body. It is suggested that some insect wings may constitute internal vapour-liquid exchange sites, where water can move from the body fluids to the intratracheal gas. Ambient and body temperature must influence rates of vapour-liquid mass transfer. If elevated body temperature promotes evaporative discharge of the metabolic water burden that has been shown to accumulate during flight in some large insects, their minimum threshold thoracic temperature for sustained flight may relate to the maintenance of water balance. The role of water economy in the early evolution of insect wings is considered. Pressure cycles might help to maintain water balance in surface-breathing insects living in fresh and saline waters, but the turbulence of the surface of the open sea might prevent truly marine forms from using this mechanism.

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Corrosion casts as a method for investigation of the insect tracheal system

Cell and Tissue Research ◽

10.1007/bf00224712 ◽

1989 ◽

Vol 256 (1) ◽

Cited By ~ 14

Author(s):

EricP. Meyer

Keyword(s):

Corrosion Casts ◽

Tracheal System

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Diffusion In Insect Wing Muscle, The Most Active Tissue Known

Journal of Experimental Biology ◽

10.1242/jeb.41.2.229 ◽

1964 ◽

Vol 41 (2) ◽

pp. 229-256 ◽

Cited By ~ 3

Author(s):

TORKEL WEIS-FOGH

Keyword(s):

Liquid Phase ◽

Safety Factor ◽

Metabolic Rates ◽

High Concentration ◽

Tracheal System ◽

Insect Wing ◽

Main Site ◽

Normal Diffusion ◽

Large Fibre ◽

Very High

1. The tracheal system of insect wing muscle is so dense that between 10-1 and 10-3 of any cut area is occupied by air tubes. In most cases, air tube diffusion of O2 and CO2 through the muscle is therefore several thousand times quicker than diffusion in the liquid phase. 2. In large insects the primary tracheal supply must be strongly ventilated while diffusion is sufficient in the remaining part of the air tubes, even at the highest metabolic rates encountered in any insect. 3. The tracheoles represent the main site of exchange between the gaseous and the liquid phase while the tracheae are of little significance in this respect. The fibres cannot exceed about 20 µ in diameter unless the tracheoles indent the surface and become ‘internal’. 4. Muscular pumping of air and blood due to shortening is of little importance for the exchange of gases but of major importance for the supply with fuel for combustion. However, the large fibre diameters and the tidal nature of the pumping necessitates a very high concentration of fuel in the haemolymph. The high concentration of trehalose in insect blood is considered to be an essential adaptation to flapping flight. 5. The transport by diffusion of O2 and CO2 was followed in detail in a number of concrete examples in the gaseous as well as in the liquid phase. Within a safety factor of 2-3, the rate of transport was always found to be adequate. There is no reason to suggest other mechanisms than a simple, normal diffusion.

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ribbon encodes a novel BTB/POZ protein required for directed cell migration in Drosophila melanogaster

Development ◽

10.1242/dev.128.15.3001 ◽

2001 ◽

Vol 128 (15) ◽

pp. 3001-3015 ◽

Cited By ~ 1

Author(s):

Pamela L. Bradley ◽

Deborah J. Andrew

Keyword(s):

Cell Migration ◽

Wnt Signaling ◽

Signaling Pathways ◽

Egf Receptor ◽

Tracheal System ◽

Directed Cell Migration ◽

Posterior Migration ◽

And Function ◽

Dorsal Epidermis ◽

Anterior Posterior

During development, directed cell migration is crucial for achieving proper shape and function of organs. One well-studied example is the embryonic development of the larval tracheal system of Drosophila, in which at least four signaling pathways coordinate cell migration to form an elaborate branched network essential for oxygen delivery throughout the larva. FGF signaling is required for guided migration of all tracheal branches, whereas the DPP, EGF receptor, and Wingless/WNT signaling pathways each mediate the formation of specific subsets of branches. Here, we characterize ribbon, which encodes a BTB/POZ-containing protein required for specific tracheal branch migration. In ribbon mutant tracheae, the dorsal trunk fails to form, and ventral branches are stunted; however, directed migrations of the dorsal and visceral branches are largely unaffected. The dorsal trunk also fails to form when FGF or Wingless/WNT signaling is lost, and we show that ribbon functions downstream of, or parallel to, these pathways to promote anterior-posterior migration. Directed cell migration of the salivary gland and dorsal epidermis are also affected in ribbon mutants, suggesting that conserved mechanisms may be employed to orient cell migrations in multiple tissues during development.

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The Post-embryonic Development of the Tracheal System in Drosophila melanogaster

Journal of Cell Science ◽

10.1242/jcs.s3-98.41.123 ◽

1957 ◽

Vol s3-98 (41) ◽

pp. 123-150

Author(s):

JOAN M. WHITTEN

Keyword(s):

Drosophila Melanogaster ◽

Adult Stage ◽

Larval Instar ◽

Pupal Stage ◽

Tracheal System ◽

True Nature ◽

The Third ◽

Air Sacs ◽

Abdominal Region ◽

Pupal Cuticle

The fate of the tracheal system is traced from the first larval instar to the adult stage. The basic larval pattern conforms to that shown for other Diptera Cyclorrhapha (Whitten, 1955), and is identical in all three instars. According to previous accounts the adult system directly replaces the larval: the larval system is partly shed, partly histolysed, and the adult system arises from imaginal cell clusters independently of the preceding larval system. In contrast, it is shown here that in the cephalic, thoracic, and anterior abdominal region there is a definite continuity in the tracheal system, from larval, through pupal to the adult stage, whereas in the posterior abdominal region the larval system is histolysed, and the adult system is independent of it in origin. Moreover, in the pupal stage this region is tracheated by tracheae arising from the anterior abdominal region and belonging to a distinct pupal system. Moulting of the tracheal linings is complete at the first and second larval ecdyses, but incomplete at the third larval-pupal and pupal-adult ecdyses. In consequence, in both pupal and adult systems there are tracheae which are secreted around preexisting tracheae, others formed as new ‘branch’ tracheae, and those which have been carried over from the previous instar. In the adult the newly formed tracheae of the posterior abdominal region fall into a fourth category. Most of the adult thoracic air sacs correspond to new ‘branch’ tracheae of other instars. The pre-pupal moult and instar are discussed with reference to the tracheal system and tentative suggestions are made concerning the true nature of the pre-pupal cuticle. There is no pre-pupal tracheal system. Events traced for Drosophila would seem to be general for Cyclorrhapha, both Acalypterae and Calypterae. The separate fates of the anterior and posterior abdom inal systems, in contrast with the straightforward development in Dipterc Nematocera, would appear to mark a distinct step in the evolution of the system in Diptera.

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THE ORGANIZATION AND INNERVATION OF THE LUMINESCENT ORGAN IN A FIREFLY, PHOTURIS PENNSYLVANICA (COLEOPTERA)

The Journal of Cell Biology ◽

10.1083/jcb.16.2.323 ◽

1963 ◽

Vol 16 (2) ◽

pp. 323-359 ◽

Cited By ~ 60

Author(s):

David S. Smith

Keyword(s):

Electron Microscope ◽

Synaptic Vesicles ◽

Light Emission ◽

Nerve Endings ◽

Tracheal Epithelium ◽

Nerve Terminals ◽

Tracheal System ◽

Physiological Evidence ◽

Effector System

The organization of the luminescent organ of an adult firefly has been studied with the electron microscope, and particular attention has been given to the disposition of nerve terminals within the organ. The cytological structure of the cells of the tracheal system, the peripheral and terminal axons, the photocytes and the cells of the dorsal ("reflecting") layer is described. Previous observations on the peripheral course of nerve branches alongside the tracheal trunks at the level of the dorsal layer and photocyte epithelium have been confirmed, and specialised nerve endings containing axoplasmic components structurally identical with "synaptic vesicles" and "neurosecretory droplets" have been identified, not in association with the surface of the photocytes, but lying between the apposed surfaces of two components of the tracheal epithelium: the tracheal end-cell and the tracheolar cell. These cytological findings are discussed in terms of available biochemical and physiological evidence concerning the mechanism of light emission in the firefly, especially with respect to the possible role of chemical "transmitter" action in triggering a response in a luminescent effector system.

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Bursaphelenchus doui Braasch, Gu, Burgermeister & Zhang, 2005 (Aphelenchida: Parasitaphelenchidae), an associate of Monochamus subfasciatus Bates (Coleoptera: Cerambycidae) and Pinus densiflora Sieb. & Zucc.

Nematology ◽

10.1163/156854108783360195 ◽

2008 ◽

Vol 10 (1) ◽

pp. 69-78 ◽

Cited By ~ 22

Author(s):

Natsumi Kanzaki ◽

Takuya Aikawa ◽

Noritoshi Maehara ◽

Kazuma Matsumoto

Keyword(s):

Pinus Densiflora ◽

Large Subunit ◽

Forest Products ◽

Original Description ◽

Small Subunit ◽

Black Pine ◽

Inoculation Test ◽

Tracheal System ◽

Chinese Populations ◽

Longhorn Beetle

Abstract Bursaphelenchus doui was isolated from a dead Japanese red pine, Pinus densiflora, in Shizuoka, and from the tracheal system of a species of longhorn beetle, Monochamus subfasciatus, collected at Tama Forest Science Garden of Forestry and Forest Products Research Institute, Tokyo, Japan. The Japanese populations of B. doui were compared with the original description of material obtained from coniferous packaging materials imported from Taiwan and Korea to continental China. Additional characters from the Japanese population include a constricted female mucron with a step-like appearance and several morphometric values. The molecular profiles of the Japanese B. doui populations were determined by DNA sequencing and ITS-RFLP profiles and were compared with those of the Taiwanese and Chinese populations of B. doui and other species in the genus. The phylogenetic analysis of the small subunit and large subunit ribosomal DNA indicated that B. doui is clearly included in the xylophilus-group of the genus Bursaphelenchus and may be close to B. conicaudatus and B. luxuriosae. The potential risk of B. doui for pine species is considered to be relatively low because B. doui did not display any pathogenicity to Japanese black pine in an inoculation test.

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