BIOL 4010 Lecture Notes - Lecture 13: Aestivation, Tardigrade, Copepod
2 May 2018
School
Department
Course
Professor
Deep Sea Adaptations
Two types of metabolic depression: dormancy and cryptobiosis
Dormancy (hypometabolism)
• Diapause
• Torpor
• Hibernation
• Aestivation
Cryptobiosis (ametabolism) *extreme metabolic shut down
• Anhydrohydrobiosis (no water)
• Cryobiosis (freezing)
• Osmobiosis (extreme salts/ions)
• Anoxybiosis (no oxygen)
Depressed MR / Resting MR (D/R ratio)
Taxonomic Group
D/R
Physiological State
Artemia
0
Anhydrobiotic cyst
Tardigrade
0.00004
Anhydrobiotic
Nematode
0.0006
Anhydrobiotic larvae
Insect
0.08
Dormant egg (diapause)
Turtle
0.15
Anaerobic
Snail
0.18
Estivating
Fish
0.20
Estivating
Insect
0.26
Dormant pupa (diapause)
Amphibian
0.29
Estivating
Reptile
0.41
Estivating
Mammals and Birds
0.63-1.0
Hibernating
Mammals and Birds
1.0
Estivating
Diapause: a period of suspended development in insect/invertebrate/mammal embryo, especially during
unfavourable environmental conditions
• Insect diapause:
o Larval diapause (caterpillars, beetles)
o Pupal diapause - massive metabolic reorganization is paused (caterpillar)
o Adult diapause (beetle)
• Zooplankton diapause:
o Depends on time of year
o Copepod growth occurs from May-October with increase in phytoplankton
• Phytoplankton concentration drops significantly in March and then slowly increases
• Increase in temperature is associated with the exit of diapause
o In not all species
o *see lifecycle
o Lipids may have important role in diapause to reduce metabolic rate
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• Mammals
o Embryonic diapause = delayed implantation
o The advantage of embryonic diapause is that the timing of mating can be separated from the
time of birth, so that the animal can deliver young at a time when conditions are optimal for
survival
o Seen in:
• Mouse
• Mink
• Wallaby
• Armadillo
• Feathertail glider
• Honey possum
• …and many more
o Strategy:
• Mink
▪ Mating occurs in Feb-March
▪ Reactivated at end of March (=seasonal quiescence)
▪ Birth occurs in May
▪ *hormones cause reactivation and diapause
• Red Deer:
▪ Mating occurs in August
▪ Embryo almost immediate enters diapause until the end of December
▪ Reactivated beginning of January
▪ Birth occurs in May
▪ *nutritionally driven
o Lactational Diapause:
• Kangaroo
▪ First young: true gestation - birth - sucking in couch - suckling on foot
▪ Second young: mating occurs right after birth of first, and then enters diapause
• Birth occurs after joey leaves pouch
▪ Third young: mating occurs right after birth of second
▪ *see slide
• Seasonal diapause in the Annual killifish (Austrofundulus limnaeus)
o Two main groups: one in Africa and one in South America
o Enters diapause via diapause-specific maternal mRNA (due to decrease in temperature or no
light)
o Increase in temperature or light induces escape of diapause (via deactivation of diapause-
specific maternal mRNA)
o Have shortest vertebrate lifespan
o Adaptation to ephemeral water supply
• Adults die when precipitation stops and embryos are in diapause
• *note: microRNA (miRNA) is a small non-coding RNA molecule (of ~22 nucleotides) found in
plants, animals and some viruses, that functions in RNA silencing and post-transcriptional
regulation of gene expression
o The function of miRNAs appears to be in gene regulation
o For that purpose, miRNA is complementary to a part of one or more messenger RNAs
(mRNA)
o *see slide
Anoxybiosis (lack of oxygen):
• Brine shrimp (Artemia spp.)
find more resources at oneclass.com
find more resources at oneclass.com
Document Summary
Two types of metabolic depression: dormancy and cryptobiosis. Cryptobiosis (ametabolism) *extreme metabolic shut down: anhydrohydrobiosis (no water, cryobiosis (freezing, osmobiosis (extreme salts/ions, anoxybiosis (no oxygen) Diapause: a period of suspended development in insect/invertebrate/mammal embryo, especially during unfavourable environmental conditions. Increase in temperature is associated with the exit of diapause. If conditions are favorable, will enter development and become nauplius larva. Intracellular ph decreases with anoxic incubation: when v-atpase were reactivated, embryo began developing. Intracellular ph increases with aerobic recovery: vacuolar proton atpase (v-atpase, *see structure. If pre-incubated with bafilomycin (inhibitor) ph is lower initially with increased depression of ph: recovery is profoundly reduced. There are three states of biological organization: alive, dead, cryptobiotic (anhydrobiotic) Anhydrobiosis (lack of water): seen in , rotifers, tardigrades, brine shrimp, nematodes, hydration, 0 - 0. 3 = ametabolic, 0. 3 - 0. 6 = restricted metabolism, 0. 6 - 1. 4 = conventional metabolism. *without strategy cannot survive below 30% hydration: ex.
