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- Gennser, Mikael, et al.
(författare)
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Effects of hyperbaric pressure and temperature on atria from ectotherm animals (Rana pipiens and Anguilla anguilla)
- 1990
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Ingår i: Comparative Biochemistry and Physiology - Part A. - : Elsevier BV. - 0300-9629. ; 95:2, s. 219-228
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Tidskriftsartikel (refereegranskat)abstract
- 1. Spontaneously beating atria from frogs (R. pipiens) and eels (A. anguilla) were compressed hydraulically to 10 MPa. Effects on beating frequency and twitch tension were studied. 2. At low temperatures (8-10 degrees C) compression to 10 MPa caused a slowing of the beat frequency. No effects were noted at higher temperatures (16-24 degrees C). Twitch tension was decreased by pressure at low temperatures and increased at high temperatures. 3. Differences were noted between preparations from cold and warm acclimatized frogs, and from silver and yellow eels, respectively. 4. The effect of temperature acclimatization on pressure and temperature sensitivity is discussed in relation to data on cardiac phospholipid fatty acid composition.
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| 2. |
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| 3. |
- Bagatto, B., et al.
(författare)
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Physiological variability in yearling alligators: Clutch differences at rest andduring activity
- 2012
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Ingår i: Comparative Biochemistry and Physiology - Part A. - : Elsevier. - 0300-9629 .- 1095-6433. ; Part A:162, s. 44-50
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Tidskriftsartikel (refereegranskat)abstract
- The adult phenotype of an organism is the result of its genotype, the environment, and the interaction betweenthe two. Assessing the relative contribution of these factors to the final adult phenotype continues tooccupy researchers. Studies have shown clutch effects early in development but few have investigated thepersistence of clutch effects on a longer time scale. Five clutches of American alligators were reared for1 year in a common environment then assessed for the presence of clutch effects as they related to morphologicaland physiological characteristics. After 1 year, significant clutch effects were evident in all size relatedvariables despite open access to food. Additionally, lung and liver masses remained different betweenclutches after animal mass was taken into account. Although clutch had no effect on resting heart rate, itsignificantly contributed to mean arterial pressure. During swimming and exhaustive exercise, the resultingrespiratory and metabolic acidoses were strongly dependent on clutch. Therefore, while the environmentcan have significant influences on the American alligator from hatching to death, the measureable contributionof genetics to the morphology and physiology of the organism remains evident, even after 1 year ofcommon rearing conditions. It behooves researchers to acknowledge and control for clutch effects when designingexperiments.
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| 4. |
- Eme, John, et al.
(författare)
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Hypoxic alligator embryos: Chronic hypoxia, catecholamine levels and autonomic responses of in ovo alligators
- 2011
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Ingår i: Comparative Biochemistry and Physiology - Part A. - : Elsevier Inc.. - 0300-9629 .- 1095-6433. ; 160:3, s. 412-420
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Tidskriftsartikel (refereegranskat)abstract
- Hypoxia is a naturally occurring environmental challenge for embryonic reptiles, and this is the first study to investigate the impact of chronic hypoxia on the in ovo development of autonomic cardiovascular regulation and circulating catecholamine levels in a reptile. We measured heart rate (fH) and chorioallantoic arterial blood pressure (MAP) in normoxic (‘N21’) and hypoxic-incubated (‘H10’; 10% O2) American alligator embryos (Alligator mississippiensis) at 70, 80 and 90% of development. Embryonic alligator responses to adrenergic blockade with propranolol and phentolamine were very similar to previously reported responses of embryonic chicken, and demonstrated that embryonic alligator has α and β-adrenergic tone over the final third of development. However, adrenergic tone originates entirely from circulating catecholamines and is not altered by chronic hypoxic incubation, as neither cholinergic blockade with atropine nor ganglionic blockade with hexamethonium altered baseline cardiovascular variables in N21 or H10 embryos. In addition, both atropine and hexamethonium injection did not alter the generally depressive effects of acute hypoxia — bradycardia and hypotension. However, H10 embryos showed significantly higher levels of noradrenaline and adrenaline at 70% of development, as well as higher noradrenaline at 80% of development, suggesting that circulating catecholamines reach maximal levels earlier in incubation for H10 embryos, compared to N21 embryos. Chronically elevated levels of catecholamines may alter the normal balance between α and β-adrenoreceptors in H10 alligator embryos, causing chronic bradycardia and hypotension of H10 embryos measured in normoxia.
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| 7. |
- Rahlff, Janina, et al.
(författare)
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Short-term molecular and physiological responses to heat stress in neritic copepods Acartia tonsa and Eurytemora affinis
- 2017
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Ingår i: Comparative Biochemistry and Physiology - Part A. - : Elsevier. - 0300-9629 .- 1095-6433. ; 203, s. 348-358
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Tidskriftsartikel (refereegranskat)abstract
- Invertebrates inhabiting shallow water habitats represent particularly appropriate organisms for studying the acclimation potential to environmental stress, since they naturally experience large fluctuations in key abiotic factors such as temperature and salinity. We quantified the biochemical- (mRNA transcripts of 78-kDa glucose-regulated protein (grp78), 70-kDa heat shock protein (hsp70), 90-kDa heat shock protein (hsp90), protein synthesis of HSP70) and organismal- (oxygen consumption rates) level responses to acute heat stress on two neritic copepods (Acartia tonsa and Eurytemora affinis) with special emphasis on the role of short-term acclimation. Transcripts of hsp increased with increasing acute temperature exposure and protein quantities (HSP70) were detectable for 30 h. In A. tonsa, HSP70 synthesis was also associated with handling stress. In E. affinis, heat-dependent responses were detected in hsp90, grp78 (mRNA) and HSP70 (protein) expression. Acclimation to a warmer temperature significantly decreased the heat stress response in both species. In A. tonsa, short-term acclimation to heat was not detected at the organismal level via metabolic rate. This study reveals interspecific differences in both the gene expression of stress molecules (e.g. hsp90) as well as the stress factors needed to evoke a stress response (heat vs. handling). We demonstrate that cellular stress markers can be useful measures of short-term thermal acclimation in copepods, which may remain undetected by organismal-level measures.
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