Knockdown of Drosophila hemoglobin suggests a role in O 2 homeostasis

The Globin Gene Family in Arthropods: Evolution and Functional Diversity

“…HbL globins thus facilitate O 2 supply in arthropod lineages adapted to low environmental O 2 conditions [Branchiopoda, Chironomidae, Gasterophilus; for review, see Weber and Vinogradov (2001)] and some have highly specialized functions like regulating diving buoyancy in backswimmers (Matthews and Seymour, 2006;Wawrowski et al, 2012). Whether the HbL-type Glob1 of D. melanogaster is indeed also instrumental in oxidative metabolism is currently being investigated, and alternative molecular roles have been proposed on the basis of the modulation of Glob1 expression by RNA inference (Hankeln et al, 2002;Yadav et al, 2015;Gleixner et al, 2016). Genetic ablation tools including CRISPR technology will probably be required to solve these discrepancies.…”

“…In fact, we have previously reported that the HbL variants in D. melanogaster , with Glob1 on the one hand and a duplicated gene pair named Glob2 and 3 on the other, display completely different structural characteristics and gene expression profiles. While Glob1 is currently thought to fulfill a role associated with oxidative metabolism in tracheoles and fat body cells of embryonal larval and adult flies ( Hankeln et al, 2002 ; Gleixner et al, 2008 , 2016 ), Glob2 and 3 are exclusively expressed during spermatogenesis and may be important for male fertility ( Gleixner et al, 2012 ). In conclusion, the multiple gene duplication events observed within the HbL class may have provided the basis for neo-functionalization events in the different arthropod lineages, which of course has to be proven experimentally.…”

“…In larval and adult Drosophila , Glob1 is mainly expressed in tracheal cells and the fat body ( Hankeln et al, 2002 ). Data from knockdown experiments indicate that Glob1 may play a role in O 2 metabolism of insects ( Gleixner et al, 2016 ), although a different role for Glob1 in maintenance of the cytoskeleton was recently proposed ( Yadav and Sarkar, 2016 ; Yadav et al, 2018 ). Drosophila has two additional globins, Glob2 and 3, which are structurally derived and specifically expressed in the testis ( Burmester et al, 2006 ; Gleixner et al, 2012 ).…”

Daphnia magna modifies its gene expression extensively in response to caloric restriction revealing a novel effect on haemoglobin isoform preference

“…RNA-dependent protein kinase R (PKR) is an intracellular sensor of stress that has recently been shown to also be essential for globin gene expression generally (Ilan et al, 2017). It could potentially also act in conditions of cellular stress to modulate haemoglobin expression, while in Drosophila knockdown of a globin gene expressed in the trachea reduces survival under hypoxia (Gleixner et al, 2016;Harrison et al, 2018), presumably due to a role in providing adequate oxygen levels. More immediately, studies of Hb response to environmental stressors in Daphnia should consider differential isoform usage following our insights here, in addition to Hb gene-copy usage.…”

Drosophila glob1 is required for the maintenance of cytoskeletal integrity during oogenesis

“…Moreover, there is no obvious hypoxic stage during their life cycle (Mangum, ; Burmester et al, ; Burmester and Hankeln, ). Although the role of glob1 has been suggested in O 2 metabolism (Gleixner et al, ), it is rather unlikely that multiple globins in Drosophila are exclusively involved in O 2 management. We have previously demonstrated that glob1 expresses ubiquitously during embryonic and larval development, and its reduced expression resulted in manifestation of various developmental and cellular anomalies, along with embryonic and larval lethality, increased level of cellular reactive oxygen species (ROS), poor musculature, locomotor and flight impairments, early aging, and premature death of adult escapers (Yadav et al, ).…”