Comparative Biochemistry and Physiology Part A: Physiology最新文献

The effects of hypoxia, sodium azide and pentachlorophenol (PCP) exposure on high-energy phosphorylated compounds, intracellular pH (pH_i) and intracellular free Mg²⁺ (Mg_f) in intact red abalone (Haliotis rufescens) were determined using ³¹P-NMR. Abalone made hypoxic by bubbling sea water with N₂ showed modest changes in phosphoarginine (PA) and inorganic phosphate (P_i) concentrations, no significant changes in pH_i and a moderate decrease in Mg_f that was not statistically significant. Azide (50 mg/l) exposed animals displayed severe declines in PA dropping to 0.53 of reference values, coupled with large increases in P_i to 10.66 times resting concentrations that occurred just after the 2-hr exposure period. pH_i also showed significant declines from a resting value of 7.17-7.06 (P < 0.05) but fully recovered by the end of the 6-hr clean seawater recovery period, whereas Mg_f concentrations declined slightly during the exposure period but increased by 18% at the end of the recovery period relative to reference Mg_f. PCP (1.2 mg/l) exposed animals displayed similar increases and declines in P_i and PA, respectively, as did azide-exposed animals by the end of the exposure period, but recovery was much slower and occurred in a bimodal fashion with some animals completely recovering at the end of 6 hr and others essentially stabilized at the end of the exposure period and did not show any significant changes during the recovery period.

The cellular signalling pathways participating in physiological color change are reviewed, particularly in crustaceans, teleosts, amphibians, and reptiles. This review is an attempt to summarize what is known and to raise some hypotheses about basic questions still to be elucidated. The first picture that emerges from the literature is that the transduction pathways are identical in the various types of chromatophores of a single species, except for the iridophore. The cAMP-dependent pathway has been well conserved throughout evolution; cAMP increase is the pigment dispersion signal whereas the nucleotide decrease leads to granule aggregation. On the other hand, the Ca²⁺-dependent pathways evoke pigment aggregation in teleosts and crustaceans, and dispersion in amphibians and probably reptiles as well. Another interesting point is the ultimate convergence of the signalling pathways of different agonists inducing the same response in one chromatophore type. A hypothesis is raised about why different chromatophores behave differently in the absence of agonists, that is, why some are punctate, whereas others are stellate.

An inflammatory reaction was induced in grass-cutters (Thryonomys swinderianus) by injecting turpentine. The changes in the plasma haptoglobin, fibrinogen, α₂ macroglobulin and immunoglobulin G was followed for 23 days by immunonephelometry. The results were compared to rat and rabbit. The showed that (a) the inflammatory reaction is delayed in the grass-cutter compared to rats and rabbits; (b) the concentration of haptoglobin increases less than in rat and rabbit; (c) the fibrinogen concentration is very low in the grass-cutter, despite hypercoagulability of blood; (d) the changes in the plasma α₂-macroglobulin in the grass-cutter seems to be comparable to that of rabbit α₁ macroglobulin in amplitude and in its slow return to the initial concentration; and (e) fibrinogen and haptoglobin are suitable markers for grass-cutter inflammation monitoring.