Respiration and acid-base balance in the salamander,Ambystoma tigrinum: Influence of temperature acclimation and metamorphosis

Summary Effects of temperature acclimation (5 or 25 °C for 2–4 weeks) and metamorphosis on oxygen uptake, acid-base balance and blood-O₂ affinity have been investigated inAmbystoma tigrinum. The results differ from previous studies in three ways. (1) The transition from gilled to gill-less adults had no effect on the O₂ affinity of blood. (2) Cold acclimation increased blood O₂ affinity in neotenes and had no effect in adults. (3) O₂ uptake increased, rather than decreased, after acclimation to a higher temperature. The results resemble previous studies also in three ways. (1) O₂ uptake increased with the transition from gilled-neotenes to gill-less adults as did the dependence on air-breathing. (2) Metamorphosis resulted in CO₂ retention and a fall in arterial pH. (3) The temperature coefficient of blood pH was about –0.014dpH/dT in vivo and in vitro. The physiological significance of the results is discussed with respect to the natural history, modes of breathing, and dependance on aerial respiration ofAmbystoma tigrinum.     

Immunofluorescence studies of neurofilaments in the rat and human peripheral and central nervous system

Localization of antisera to neurofilament antigens derived from rat peripheral nerve was carried out in tissues of rat and human peripheral and central nervous systems by indirect immunofluorescence. Unfixed and chloroform-methanol-fixed frozen sections of tissues were incubated in purified IgG of the experimental rabbit antisera and subsequently exposed to goat anti-rabbit IgG conjugated with fluorescein isothiocyanate. Control studies were conducted on identical tissue preparations incubated in the same concentrations of nonspecific rabbit IgG or in experimental rabbit IgG absorbed with extracts of rat peripheral nerve containing neurofilament antigen. Extensive immunofluorescence was observed in rat and human peripheral and central nervous systems. The distribution and configuration of immunofluorescence corresponded to neurofilament-rich structural components of these tissues. Prominent immunofluorescence was also noted in neuronal cell bodies of spinal sensory ganglia, especially in perikarya of the large neuronal type. Immunofluorescence of the central nervous system was located predominantly in myelinated axons of the white matter in cerebrum, cerebellum, brain stem, and spinal cord. Less intense immunofluorescence was also seen in neuronal perikarya and in short thin linear processes of grey matter.