Mount Desert Island Biological Laboratory

About: Mount Desert Island Biological Laboratory is a nonprofit organization based out in Bar Harbor, Maine, United States. It is known for research contribution in the topics: Squalus acanthias & Spiny dogfish. The organization has 898 authors who have published 819 publications receiving 34283 citations.

Bromination of phthalein dyes by the uterus of the dogfish, squalus acanthias.

Abstract: SummaryThe observation that phenol red is brominated by the pregnant dogfish uterus in vivo was further studied and chlorophenol red, metacresol purple, and fluorescein were also found to be brominated. Some evidence was obtained that p-hydroxybenzoic acid and phenol were similarly brominated. The bromine was derived from an extraneous source. The site of bromination seemed to reside in the epithelium of the uterus. Bromination was also demonstrated by in vitro incubation, the pH optimum was found to be 7.4.

Effect of anisotonic media on cell volume and electrolyte fluxes in slices of the dogfish (Squalus acanthias) rectal gland

Abstract: Osmotic responses of slices of dogfish rectal gland to hypotonic (urea-free) and hypertonic media were studied. Transfer of tissue from isotonic (890 mosM) to hypotonic (550 mosM) saline produced an osmotic swelling associated with a slow net uptake of cell K+ (and Cl−) and a slow, two-component efflux of urea. Media made hypertonic (1180 mosM) by addition of urea or mannitol produced osmotic shrinkage with a net loss of KCl. The cell osmotic responses in hypotonic media were lower than predicted for an ideal osmometer. No volume regulatory responses were seen subsequent to the initial osmotic effects. The cation influx in hypotonic media lacked specificity: in the presence of 0.5 mM ouabain or in K+-free media a net influx of Na+ was found. At steady state, the cell membrane potential evaluated from the Nernst potentials of K+ and triphenylmethyl phosphonium+, was independent of medium tonicity, suggesting the membrane potential as a determinant in the cellular osmotic response. Zero-time86Rb+ fluxes were measured:86Rb+ influx was not affected by hypotonicity, implying an unchanged operation of the Na+−K+-ATPase. On the other hand,86Rb+ efflux was significantly reduced at hypotonicity; this effect was transient, the efflux returning to the control value once the new steady state of cell volume had been reached. A controlled efflux system is therefore involved in the cell osmotic response. The absence of the volume regulatory phenomenon suggests that the cells are not equipped with a volume-sensing mechanism.

The Teleostean Swim-bladder

Abstract: THE enigmatic secretion of gas into the teleostean swim-bladder has been attributed to the acidification of the blood bathing the gas gland epithelium1. The resultant local changes of pH, pCO2 and pO2 are thought to be sequestered from the rest of the circulation by counter-current exchange in the rete mirabile. This has been the only credible explanation; but its acceptance has rested upon its credibility. Even though the isolated gas gland epithelium actively converts glucose to lactic acid2, there has been no evidence, either in vivo or in vitro, for an oriented hydrogen-ion extrusion into the solution bathing the serosal surface of the epithelium, the surface normally bathed by blood.