PMID- 38264780
OWN - NLM
STAT- MEDLINE
DCOM- 20240125
LR  - 20240202
IS  - 1471-2954 (Electronic)
IS  - 0962-8452 (Print)
IS  - 0962-8452 (Linking)
VI  - 291
IP  - 2015
DP  - 2024 Jan 31
TI  - Oxygen extraction efficiency of the tidally-ventilated rectal gills of dragonfly 
      nymphs.
PG  - 20231699
LID - 10.1098/rspb.2023.1699 [doi]
LID - 20231699
AB  - Dragonfly nymphs breathe water using tidal ventilation, a highly unusual strategy 
      in water-breathing animals owing to the high viscosity, density and low oxygen 
      (O(2)) concentration of water. This study examines how well these insects extract 
      O(2) from the surrounding water during progressive hypoxia. Nymphs were attached 
      to a custom-designed respiro-spirometer to simultaneously measure tidal volume, 
      ventilation frequency and metabolic rate. Oxygen extraction efficiencies (OEE) 
      were calculated across four partial pressure of oxygen (pO(2)) treatments, from 
      normoxia to severe hypoxia. While there was no significant change in tidal 
      volume, ventilation frequency increased significantly from 9.4 +/- 1.2 breaths per 
      minute (BPM) at 21.3 kPa to 35.6 +/- 2.9 BPM at 5.3 kPa. Metabolic rate increased 
      significantly from 1.4 +/- 0.3 microl O(2) min(-1) at 21.3 kPa to 2.1 +/- 0.4 microl O(2) 
      min(-1) at 16.0 kPa, but then returned to normoxic levels as O(2) levels declined 
      further. OEE of nymphs was 40.1 +/- 6.1% at 21.3 kPa, and did not change 
      significantly during hypoxia. Comparison to literature shows that nymphs maintain 
      their OEE during hypoxia unlike other aquatic tidal-breathers and some 
      unidirectional breathers. This result, and numerical models simulating 
      experimental conditions, indicate that nymphs maintain these extraction 
      efficiencies by increasing gill conductance and/or lowering internal pO(2) to 
      maintain a sufficient diffusion gradient across their respiratory surface.
FAU - Lee, Daniel J
AU  - Lee DJ
AUID- ORCID: 0000-0002-6287-8172
AD  - Department of Zoology, University of British Columbia, Vancouver, British 
      Columbia, Canada V6T1Z4.
FAU - Matthews, Philip G D
AU  - Matthews PGD
AUID- ORCID: 0000-0003-0682-8522
AD  - Department of Zoology, University of British Columbia, Vancouver, British 
      Columbia, Canada V6T1Z4.
LA  - eng
PT  - Journal Article
DEP - 20240124
PL  - England
TA  - Proc Biol Sci
JT  - Proceedings. Biological sciences
JID - 101245157
RN  - S88TT14065 (Oxygen)
RN  - 059QF0KO0R (Water)
SB  - IM
MH  - Animals
MH  - *Gills
MH  - *Odonata
MH  - Hypoxia
MH  - Oxygen
MH  - Nymph
MH  - Water
PMC - PMC10806436
OTO - NOTNLM
OT  - dragonfly nymph
OT  - hypoxia
OT  - oxygen extraction efficiency
OT  - respirometry
OT  - spirometry
OT  - tidal ventilation
COIS- The authors have no competing interests to declare.
EDAT- 2024/01/24 06:43
MHDA- 2024/01/25 06:43
PMCR- 2025/01/24
CRDT- 2024/01/24 04:02
PHST- 2025/01/24 00:00 [pmc-release]
PHST- 2024/01/25 06:43 [medline]
PHST- 2024/01/24 06:43 [pubmed]
PHST- 2024/01/24 04:02 [entrez]
AID - rspb20231699 [pii]
AID - 10.1098/rspb.2023.1699 [doi]
PST - ppublish
SO  - Proc Biol Sci. 2024 Jan 31;291(2015):20231699. doi: 10.1098/rspb.2023.1699. Epub 
      2024 Jan 24.