Histological and ultrastructural analysis of the respiratory tracheae of Galeodes granti (Chelicerata: Solifugae)

Franz‐Guess, Sandra; Starck, J. Matthias

doi:10.1016/j.asd.2016.08.003

Cited by 9 publications

(1 citation statement)

References 24 publications

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“…Every terrestrial group of arthropods has a complex system of invaginations into the body for the direct delivery of air to tissues, principally in the form of tracheae for insects, myriapods (centipedes and millipedes), and some arachnids (e.g., solifugae [32]), or as book lungs in many spiders and all scorpions [33], and pleopod lungs in pill bugs (Oniscoidae) [34]. Because of ambiguous relationships among the 11 orders of arachnids [35], it is difficult to determine exactly how many times arachnids independently evolved tracheae, but based on structure it may have been five times (e.g., [36][37][38]). The implication of this remarkable, repeated convergence is that tracheae and book lungs are not only necessary for arthropod breathing on land, they are entirely adequate.…”

Section: Introductionmentioning

confidence: 99%

Transcriptomes reveal expression of hemoglobins throughout insects and other Hexapoda

Herhold

Davis²,

Grimaldi³

2020

PLoS ONE

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Insects have long been thought to largely not require hemoglobins, with some notable exceptions like the red hemolymph of chironomid larvae. The tubular, branching network of tracheae in hexapods is traditionally considered sufficient for their respiration. Where hemoglobins do occur sporadically in plants and animals, they are believed to be either convergent, or because they are ancient in origin and their expression is lost in many clades. Our comprehensive analysis of 845 Hexapod transcriptomes, totaling over 38 Gbases, revealed the expression of hemoglobins in all 32 orders of hexapods, including the 29 recognized orders of insects. Discovery and identification of 1333 putative hemoglobins were achieved with target-gene BLAST searches of the NCBI TSA database, verifying functional residues, secondary-and tertiary-structure predictions, and localization predictions based on machine learning. While the majority of these hemoglobins are intracellular, extracellular ones were recovered in 38 species. Gene trees were constructed via multiple-sequence alignments and phylogenetic analyses. These indicate duplication events within insects and a monophyletic grouping of hemoglobins outside other globin clades, for which we propose the term insectahemoglobins. These hemoglobins are phylogenetically adjacent and appear structurally convergent with the clade of chordate myoglobins, cytoglobins, and hemoglobins. Their derivation and co-option from early neuroglobins may explain the widespread nature of hemoglobins in various kingdoms and phyla. These results will guide future work involving genome comparisons to transcriptome results, experimental investigations of gene expression, cell and tissue localization, and gas binding properties, all of which are needed to further illuminate the complex respiratory adaptations in insects.

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