To determine whether an attenuated stress response is a general feature of Antarctic fish or is dependent on ecotype, the capacity for catecholamine synthesis within the head kidney and plasma levels of the primary stress hormones (catecholamines and cortisol) were determined in species with a range of activity patterns. Tyrosine hydroxylase (TH) activities were similar in both sluggish (Gobionotothen gibberifons, 153+/−22 nmol g(−)(1)h(−)(1), mean +/− s.e.m.) and active (Notothenia rossii, 185+/−39 nmol g(−)(1)h(−)(1), Dissostichus mawsoni, 128+/−31 nmol g(−)(1)h(−)(1)) pelagic nototheniids, but only 30 % of those in Atlantic cod (Gadus morhua, 393+/−88 nmol g(−)(1)h(−)(1)) at the same temperature. TH activities were even lower in white-blooded channichthyids (Chaenocephalus aceratus, 74+/−16 nmol g(−)(1)h(−)(1) and Champsocephalus gunnari, 53+/−17 nmol g(−)(1)h(−)(1)), although values in Chionodraco rastrospinosus were similar to red-blooded species (178+/−45 nmol g(−)(1)h(−)(1)). Circulating catecholamine levels were extremely high in all species after fishing stress, with adrenaline levels 3–4 times higher than noradrenaline levels. Cortisol levels remained low, ranging from 1.33+/−0.58 ng ml(−)(1) in Champsocephalus gunnari to 44.9+/−25.0 ng ml(−)(1)in Dissostichus mawsoni. These data suggest that depressed catecholamine synthesis is typical of Antarctic fish regardless of life style, although they are able to release extensive stores from the chromaffin tissue under conditions of extreme trauma. Cortisol does not appear to be an important primary stress hormone in these species.
In the field: an interview with Martha Muñoz
Martha Muñoz is an Assistant Professor at Yale University, investigating the evolutionary biology of anole lizards and lungless salamanders. In our new Conversation, she talks about her fieldwork in Indonesia, Costa Rica, the Dominican Republic and the Appalachian Mountains, including a death-defying dash to the top of a mountain through an approaching hurricane.
Call for new preLighters
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preLights is the preprint highlighting community supported by The Company of Biologists. At the heart of preLights are our preLighters: early-career researchers who select and write about interesting new preprints for the research community. We are currently looking for new preLighters to join our team. Find out more and apply here.
Graham Scott in conversation with Big Biology
Graham Scott talks to Big Biology about the oxygen cascade in mice living on mountaintops, extreme environments for such small organisms. In this JEB-sponsored episode, they discuss the concept of symmorphosis and the evolution of the oxygen cascade.
Trap-jaw ants coordinate tendon and exoskeleton for perfect mandible arc
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Trap-jaw ants run the risk of tearing themselves apart when they fire off their mandibles, but Greg Sutton & co have discovered that the ants simultaneously push and pull the mandibles using energy stored in a head tendon and their exoskeleton to drive the jaws in a perfect arc.
Hearing without a tympanic ear
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In their Review, Grace Capshaw, Jakob Christensen-Dalsgaard and Catherine Carr explore the mechanisms of hearing in extant atympanate vertebrates and the implications for the early evolution of tympanate hearing.
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