scholarly journals No water, no problem: stage-specific metabolic responses to dehydration stress in annual killifish embryos

2020 ◽  
Vol 223 (18) ◽  
pp. jeb231985 ◽  
Author(s):  
Daniel E. Zajic ◽  
Jonathon P. Nicholson ◽  
Jason E. Podrabsky
Keyword(s):  
Oxygen Consumption ◽  
Water Retention ◽  
Dehydration Stress ◽  
Temporary Ponds ◽  
Evaporative Water ◽  
Developmental Variation ◽  
Annual Killifish ◽  
Drought Tolerant ◽  
Consumption Rates ◽  
Austrofundulus Limnaeus

ABSTRACTAnnual killifish survive in temporary ponds by producing drought-tolerant embryos that can enter metabolic dormancy (diapause). Survival of dehydration stress is achieved through severe reduction of evaporative water loss. We assessed dehydration stress tolerance in diapausing and developing Austrofundulus limnaeus embryos. We measured oxygen consumption rates under aquatic and aerial conditions to test the hypothesis that there is a trade-off between water retention and oxygen permeability. Diapausing embryos survive dehydrating conditions for over 1.5 years, and post-diapause stages can survive for over 100 days. Diapausing embryos respond to dehydration stress by increasing oxygen consumption rates while post-diapause embryos exhibit the same or reduced rates compared with aquatic embryos. Thus, water retention does not always limit oxygen diffusion. Aerial incubation coupled with hypoxia causes some embryos to arrest development. The observed stage-specific responses are consistent with an intrinsic bet-hedging strategy in embryos that would increase developmental variation in a potentially adaptive manner.

scholarly journals Metabolomics analysis of annual killifish (Austrofundulus limnaeus) embryos during aerial dehydration stress

2020 ◽  
Vol 52 (9) ◽  
pp. 408-422
Author(s):  
Daniel E. Zajic ◽  
Jason E. Podrabsky
Keyword(s):  
Molecular Mechanisms ◽  
Dry Season ◽  
Dehydration Stress ◽  
Aerial Exposure ◽  
Ephemeral Ponds ◽  
Annual Killifish ◽  
Metabolite Profiles ◽  
Aquatic Vertebrates ◽  
Austrofundulus Limnaeus ◽  
Insight Into

The annual killifish, Austrofundulus limnaeus, survives in ephemeral ponds in the coastal deserts of Venezuela. Persistence through the dry season is dependent on drought-resistant eggs embedded in the pond sediments during the rainy season. The ability of these embryos to enter drastic metabolic dormancy (diapause) during normal development enables A. limnaeus to survive conditions lethal to most other aquatic vertebrates; critical to the survival of the species is the ability of embryos to survive months and perhaps years without access to liquid water. Little is known about the molecular mechanisms that aid in survival of the dry season. This study aims to gain insight into the mechanisms facilitating survival of dehydration stress due to aerial exposure by examining metabolite profiles of dormant and developing embryos. There is strong evidence for unique metabolic profiles based on developmental stage and length of aerial exposure. Actively developing embryos exhibit more robust changes; however, dormant embryos respond in an active manner and significantly alter their metabolic profile. A number of metabolites accumulate in aerial-exposed embryos that may play an important role in survival, including the identification of known antioxidants and neuroprotectants. In addition, a number of unique metabolites not yet discussed in the dehydration literature are identified, such as lanthionine and 2-hydroxyglutarate. Despite high oxygen availability, embryos accumulate the anaerobic end product lactate. This paper offers an overview of the metabolic changes occurring that may support embryonic survival during dehydration stress due to aerial incubation, which can be functionally tested using genetic and pharmacological approaches.

The bioenergetics of embryonic diapause in an annual killifish, austrofundulus limnaeus

1999 ◽  
Vol 202 (19) ◽  
pp. 2567-2580 ◽  
Author(s):  
J.E. Podrabsky ◽  
S.C. Hand
Keyword(s):  
Oxygen Consumption ◽  
Early Development ◽  
Energy Use ◽  
Heat Dissipation ◽  
Energy Charge ◽  
Adenylate Energy Charge ◽  
Ephemeral Ponds ◽  
Annual Killifish ◽  
Rate Of Oxygen Consumption ◽  
Austrofundulus Limnaeus

The annual killifish Austrofundulus limnaeus inhabits ephemeral ponds that dry out on a seasonal basis, thereby killing the adult and juvenile forms. Populations persist because diapausing embryos become embedded in the pond sediments. The rate of oxygen consumption of diapause II embryos is depressed by up to 90 % compared with that of developing embryos, and a parallel reduction is observed in heart rate. Developmental arrest was identified by cessation of somite proliferation and blockage of the ontogenetic increase in DNA content. Surprisingly, the arrest of metabolism and development is temporally offset as embryos reach diapause II; metabolic rate begins to decline 12 days prior to arrest of development. Release of embryos from diapause II is facilitated by increasing the light phase of the photoperiod. The rate of oxygen consumption of diapause III embryos is 84 % lower than the value preceding diapause III. The total energy flow of diapause II embryos apparently includes a contribution from anaerobic processes on the basis of calorimetric/respirometric ratios that are above the oxycaloric equivalent. Accumulations of lactate and ethanol at the expense of glycogen reserves are small or undetectable and do not account for the excess heat signal. Diapause II embryos maintain high [ATP]/[ADP] ratios and adenylate energy charge during diapause, consistent with a simultaneous depression of energy use and demand. Levels of AMP increase during early development and diapause II despite the highly charged adenylate pool. High values for [AMP]/[ATP] ratios in diapause II embryos are correlated with decreased rates of oxygen consumption and heat dissipation, which suggests a role for AMP in the depression of metabolism during early development and diapause II.

scholarly journals Oxygen consumption rates in subseafloor basaltic crust derived from a reaction transport model

2013 ◽  
Vol 4 (1) ◽  
Author(s):  
Beth N. Orcutt ◽  
C. Geoffrey Wheat ◽  
Olivier Rouxel ◽  
Samuel Hulme ◽  
Katrina J. Edwards ◽  
...  
Keyword(s):  
Oxygen Consumption ◽  
Transport Model ◽  
Consumption Rates ◽  
Reaction Transport ◽  
Basaltic Crust

The Relation of Oxygen Consumption to Body Size and to Temperature in the Larvae of Chironomus Riparius Meigen

1958 ◽  
Vol 35 (2) ◽  
pp. 383-395
Author(s):  
R. W. EDWARDS
Keyword(s):  
Oxygen Consumption ◽  
Body Size ◽  
Dry Matter ◽  
Larval Instar ◽  
Weight Ratio ◽  
Dry Weight ◽  
Chironomus Riparius ◽  
Consumption Rates ◽  
Rate Of Oxygen Consumption ◽  
Wet Weight

1. The oxygen consumption rates of 3rd- and 4th-instar larvae of Chironomus riparius have been measured at 10 and 20° C. using a constant-volume respirometer. 2. The oxygen consumption is approximately proportional to the 0.7 power of the dry weight: it is not proportional to the estimated surface area. 3. This relationship between oxygen consumption and dry weight is the same at 10 and at 20° C.. 4. The rate of oxygen consumption at 20° C. is greater than at 10° C. by a factor of 2.6. 5. During growth the percentage of dry matter of 4th-instar larvae increases from 10 to 16 and the specific gravity from 1.030 to 1.043. 6. The change in the dry weight/wet weight ratio during the 4 larval instar supports the theory of heterauxesis. 7. At 20° C., ‘summer’ larvae respire faster than ‘winter’ larvae.

scholarly journals Extreme anoxia tolerance in embryos of the annual killifish Austrofundulus limnaeus: insights from a metabolomics analysis

2007 ◽  
Vol 210 (13) ◽  
pp. 2253-2266 ◽  
Author(s):  
J. E. Podrabsky ◽  
J. P. Lopez ◽  
T. W. M. Fan ◽  
R. Higashi ◽  
G. N. Somero
Keyword(s):  
Anoxia Tolerance ◽  
Annual Killifish ◽  
Austrofundulus Limnaeus ◽  
Metabolomics Analysis
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