Cyclomorphosis in Tardigrada: adaptation to environmental constraints

Kenneth Agerlin Halberg; Dennis Persson; Hans Ramløv; Peter Westh; Reinhardt Møbjerg Kristensen; Nadja Møbjerg

doi:10.1242/jeb.029413

Cyclomorphosis in Tardigrada: adaptation to environmental constraints

Kenneth Agerlin Halberg, Dennis Persson, Hans Ramløv, Peter Westh, Reinhardt Møbjerg Kristensen, Nadja Møbjerg

Publikation: Bidrag til tidsskrift › Tidsskriftartikel › Forskning › peer review

44 Citationer (Scopus)

Abstract

Udgivelsesdato: 2009-Sep-1

Originalsprog	Engelsk
Tidsskrift	Journal of Experimental Biology
Vol/bind	212
Udgave nummer	17
Sider (fra-til)	2803-11
Antal sider	8
ISSN	0022-0949
DOI	https://doi.org/10.1242/jeb.029413
Status	Udgivet - 2009

Bibliografisk note

Keywords: Acclimatization; Animals; Invertebrates; Microscopy, Electron, Scanning; Osmolar Concentration; Osmotic Pressure; Temperature; Water-Electrolyte Balance

Adgang til dokumentet

10.1242/jeb.029413

Citationsformater

@article{b707824001e711df825d000ea68e967b,

title = "Cyclomorphosis in Tardigrada: adaptation to environmental constraints",

abstract = "Tardigrades exhibit a remarkable resilience against environmental extremes. In the present study, we investigate mechanisms of survival and physiological adaptations associated with sub-zero temperatures and severe osmotic stress in two commonly found cyclomorphic stages of the marine eutardigrade Halobiotus crispae. Our results show that only animals in the so-called pseudosimplex 1 stage are freeze tolerant. In pseudosimplex 1, as well as active-stage animals kept at a salinity of 20 ppt, ice formation proceeds rapidly at a crystallization temperature of around -20 degrees C, revealing extensive supercooling in both stages, while excluding the presence of physiologically relevant ice-nucleating agents. Experiments on osmotic stress tolerance show that the active stage tolerates the largest range of salinities. Changes in body volume and hemolymph osmolality of active-stage specimens (350-500 microm) were measured following salinity transfers from 20 ppt. Hemolymph osmolality at 20 ppt was approximately 950 mOsm kg(-1). Exposure to hypo-osmotic stress in 2 and 10 ppt caused (1) rapid swelling followed by a regulatory volume decrease, with body volume reaching control levels after 48 h and (2) decrease in hemolymph osmolality followed by a stabilization at significantly lower osmolalities. Exposure to hyperosmotic stress in 40 ppt caused (1) rapid volume reduction, followed by a regulatory increase, but with a new steady-state after 24 h below control values and (2) significant increase in hemolymph osmolality. At any investigated external salinity, active-stage H. crispae hyper-regulate, indicating a high water turnover and excretion of dilute urine. This is likely a general feature of eutardigrades.",

author = "Halberg, {Kenneth Agerlin} and Dennis Persson and Hans Raml{\o}v and Peter Westh and Kristensen, {Reinhardt M{\o}bjerg} and Nadja M{\o}bjerg",

note = "Keywords: Acclimatization; Animals; Invertebrates; Microscopy, Electron, Scanning; Osmolar Concentration; Osmotic Pressure; Temperature; Water-Electrolyte Balance",

year = "2009",

doi = "10.1242/jeb.029413",

language = "English",

volume = "212",

pages = "2803--11",

journal = "Journal of Experimental Biology",

issn = "0022-0949",

publisher = "The/Company of Biologists Ltd.",

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TY - JOUR

T1 - Cyclomorphosis in Tardigrada: adaptation to environmental constraints

AU - Halberg, Kenneth Agerlin

AU - Persson, Dennis

AU - Ramløv, Hans

AU - Westh, Peter

AU - Kristensen, Reinhardt Møbjerg

AU - Møbjerg, Nadja

N1 - Keywords: Acclimatization; Animals; Invertebrates; Microscopy, Electron, Scanning; Osmolar Concentration; Osmotic Pressure; Temperature; Water-Electrolyte Balance

PY - 2009

Y1 - 2009

N2 - Tardigrades exhibit a remarkable resilience against environmental extremes. In the present study, we investigate mechanisms of survival and physiological adaptations associated with sub-zero temperatures and severe osmotic stress in two commonly found cyclomorphic stages of the marine eutardigrade Halobiotus crispae. Our results show that only animals in the so-called pseudosimplex 1 stage are freeze tolerant. In pseudosimplex 1, as well as active-stage animals kept at a salinity of 20 ppt, ice formation proceeds rapidly at a crystallization temperature of around -20 degrees C, revealing extensive supercooling in both stages, while excluding the presence of physiologically relevant ice-nucleating agents. Experiments on osmotic stress tolerance show that the active stage tolerates the largest range of salinities. Changes in body volume and hemolymph osmolality of active-stage specimens (350-500 microm) were measured following salinity transfers from 20 ppt. Hemolymph osmolality at 20 ppt was approximately 950 mOsm kg(-1). Exposure to hypo-osmotic stress in 2 and 10 ppt caused (1) rapid swelling followed by a regulatory volume decrease, with body volume reaching control levels after 48 h and (2) decrease in hemolymph osmolality followed by a stabilization at significantly lower osmolalities. Exposure to hyperosmotic stress in 40 ppt caused (1) rapid volume reduction, followed by a regulatory increase, but with a new steady-state after 24 h below control values and (2) significant increase in hemolymph osmolality. At any investigated external salinity, active-stage H. crispae hyper-regulate, indicating a high water turnover and excretion of dilute urine. This is likely a general feature of eutardigrades.

AB - Tardigrades exhibit a remarkable resilience against environmental extremes. In the present study, we investigate mechanisms of survival and physiological adaptations associated with sub-zero temperatures and severe osmotic stress in two commonly found cyclomorphic stages of the marine eutardigrade Halobiotus crispae. Our results show that only animals in the so-called pseudosimplex 1 stage are freeze tolerant. In pseudosimplex 1, as well as active-stage animals kept at a salinity of 20 ppt, ice formation proceeds rapidly at a crystallization temperature of around -20 degrees C, revealing extensive supercooling in both stages, while excluding the presence of physiologically relevant ice-nucleating agents. Experiments on osmotic stress tolerance show that the active stage tolerates the largest range of salinities. Changes in body volume and hemolymph osmolality of active-stage specimens (350-500 microm) were measured following salinity transfers from 20 ppt. Hemolymph osmolality at 20 ppt was approximately 950 mOsm kg(-1). Exposure to hypo-osmotic stress in 2 and 10 ppt caused (1) rapid swelling followed by a regulatory volume decrease, with body volume reaching control levels after 48 h and (2) decrease in hemolymph osmolality followed by a stabilization at significantly lower osmolalities. Exposure to hyperosmotic stress in 40 ppt caused (1) rapid volume reduction, followed by a regulatory increase, but with a new steady-state after 24 h below control values and (2) significant increase in hemolymph osmolality. At any investigated external salinity, active-stage H. crispae hyper-regulate, indicating a high water turnover and excretion of dilute urine. This is likely a general feature of eutardigrades.

U2 - 10.1242/jeb.029413

DO - 10.1242/jeb.029413

M3 - Journal article

C2 - 19684214

SN - 0022-0949

VL - 212

SP - 2803

EP - 2811

JO - Journal of Experimental Biology

JF - Journal of Experimental Biology

IS - 17

ER -