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.

Generating new marine cell lines and transgenic species--conference summary.

Abstract: Marine species offer a tremendous diversity of life histories, physiologies, genetics, behaviors, and biologies, reflecting myriad adaptations to the water environment. Historically, marine vertebrates, particularly fish, have played significant roles in a wide range of disciplines, including environmental toxicology, genetics, developmental biology, and physiology, among others. Much still remains to be learned from these animals, and there is a growing need for new marine models. Models for expression of marine animal genes have been limited to heterologous expression systems. While there is still a great deal to gain from heterologous expression systems, the interactions of genes with one another can best be determined in homologous expression systems where appropriate interactions are possible. This has become particularly important with the development of functional genomics in marine models. These homologous gene expression systems will be key to the use of functional genomics for marine animal molecular physiology and toxicology.

Isosmotic swelling of skate (Raja erinacea) red blood cells causes a volume regulatory release of intracellular taurine

Abstract: Animal cells swell when placed in a hypotonic medium and then regulate their volume by releasing intracellular solutes. The aim of this study was to determine whether hypoosmolarity or cell swelling is the stimulus that triggers the release of solutes. Swelling skate red blood cells (RBC) by placing them in isosmotic media containing rapidly penetrating solutes (NH4Cl, ethylene glycol) caused increased release of taurine from the cells. Isosmotic swelling also increased the cellular levels of radiolabeled diacylglycerol, a second messenger previously implicated in volume regulation by skate RBC. These results indicate that the release of intracellular solutes by hypoosmotically stressed skate RBC is brought about by cell swelling.

Tyrosine Phosphorylation of CD2AP Affects Stability of the Slit Diaphragm Complex.

Abstract: Background CD2-associated protein (CD2AP), a slit diaphragm-associated scaffolding protein involved in survival and regulation of the cytoskeleton in podocytes, is considered a "stabilizer" of the slit diaphragm complex that connects the slit diaphragm protein nephrin to the cytoskeleton of the cell. Tyrosine phosphorylation of slit diaphragm molecules can influence their surface expression, but it is unknown whether tyrosine phosphorylation events of CD2AP are also physiologically relevant to slit diaphragm stability. Methods We used isoelectric focusing, western blot analysis, and immunofluorescence to investigate phosphorylation of CD2AP, and phospho-CD2AP antibodies and site-directed mutagenesis to define the specific phosphorylated tyrosine residues. We used cross-species rescue experiments in Cd2apKD zebrafish and in Drosophila cindrRNAi mutants to define the physiologic relevance of CD2AP phosphorylation of the tyrosine residues. Results We found that VEGF-A stimulation can induce a tyrosine phosphorylation response in CD2AP in podocytes, and that these phosphorylation events have an important effect on slit diaphragm protein localization and functionality in vivo. We demonstrated that tyrosine in position Y10 of the SH3-1 domain of CD2AP is indispensable for CD2AP function in vivo. We found that the binding affinity of nephrin to CD2AP is significantly enhanced in the absence of Y10; however, unexpectedly, this increased affinity leads not to stabilization but to functional impairment of the glomerular filtration barrier. Conclusions Our findings provide insight into CD2AP and its phosphorylation in the context of slit diaphragm functionality, and indicate a fine-tuned affinity balance of CD2AP and nephrin that is influenced by receptor tyrosine kinase stimulation.

Enhancement of aster‐induced furrowing activity by a factor associated with the nucleus

Abstract: The purpose of this investigation was to determine whether asters that develop in the absence of nuclear material have the normal ability to cause surface contraction and furrows. Experimental cells were confined in silicone rubber tubes with flattened lumens. The lumen roof was thin enough to permit deformation or perforation of the contained eggs by pressure with glass tools. When a flattened, elongate egg was perforated at its midpoint with a relatively large glass ball before nuclear membrane breakdown, the positions of the asters and nucleus were determined by chance. When the nucleus and asters were on the same side of the perforation, normal furrows developed. When the nucleus was separated from the aster pair, only ephemeral furrows developed. When the asters straddled the perforation so that only one of the asters was associated with the nucleus, ephemeral furrowing activity was most pronounced at the nucleated end of the cell. The asters of cells that were kneaded before insertion in the flattened capillary were often farther apart than normal, and the nucleus was more closely associated with one aster than the other. Constrictions developed in the planes of both asters, but only those associated with the aster closest to the nucleus persisted to produce two aster-containing cells, only one of which contained a nucleus. In subsequent division cycles, asters reproduced and developed in both cells, but only the progeny of the nucleated cell formed permanent furrows. The normal furrow-inducing capacity of the asters appears to depend in part on the presence of a factor associated with the nucleus.

Renal handling of 2,4-D by the dogfish shark (Squalus acanthias).

Abstract: 1. The renal clearance of 2,4-dichlorophenoxyacetate (2,4-D) was studied in the dogfish shark, Squalus acanthias.2. The clearance of total 2,4-D was more than 25 times greater then the glomerular filtration rate, which indicated that 2,4-D was secreted by the kidney.3. The secretion of total 2,4-D was decreased by bromocresol green, an inhibitor of organic anion secretion, which also produced a concurrent decrease in the glomerular filtration rate.4. As previously determined, 2,4-D was eliminated in the urine as the taurine conjugate (≈95% of the excretion products). The plasma of the dogfish shark, however, contained primarily unconjugated 2,4-D (≈90%) and only a minor amount of the taurine conjugate (≈5%). The limited amount of the taurine conjugate in the plasma cannot account for its urinary excretion. Apparently 2, 4-D is transported into the renal tubular cell, after which 2,4-D is conjugated with taurine before elimination into the urine.