Biochemical studies of taste sensation. XI. Isolation, characterization and taste ligand binding activity of plasma membranes from catfish taste tissue

Variants of creatine kinase-MM (variant of ATP:creatine N-phosphotransferase, EC 2.7.3.2), present in human heart and skeletal muscle, have been purified to homogeneity using DEAE-Sepharose column chromatography and column chromatofocusing techniques. Creatine kinase-MM I-IV were present in both heart and skeletal muscle, while MM-V was found only in heart. The number, ratio and elution profile of the variants during chromatofocusing remained identical even when they were purified in the presence of proteinase inhibitors. MM-I-V, on chromatofocusing, were eluted at pH 8.3, 7.9, 7.6, 7.2 and 6.8, respectively. Isoelectric focusing revealed the pI of MM-I-V to be 7.2, 6.9, 6.7, 6.4 and 6.2. Sodium dodecyl sulfate (SDS) polyacrylamide gel electrophoresis showed a doublet pattern for creatine kinase-MM variants III-V. However, polyacrylamide gel electrophoresis without SDS indicated homogeneity because each variant showed a single band. The doublet pattern observed in the presence of SDS may reflect the presence of two subunits of slightly different mass.     

Elemental Fingerprinting of Mussel Shells to Predict Population Sources and Redistribution Potential in the Gulf of Maine

As the climate warms, species that cannot tolerate changing conditions will only persist if they undergo range shifts. Redistribution ability may be particularly variable for benthic marine species that disperse as pelagic larvae in ocean currents. The blue mussel, Mytilus edulis, has recently experienced a warming-related range contraction in the southeastern USA and may face limitations to northward range shifts within the Gulf of Maine where dominant coastal currents flow southward. Thus, blue mussels might be especially vulnerable to warming, and understanding dispersal patterns is crucial given the species'' relatively long planktonic larval period (>1 month). To determine whether trace elemental “fingerprints” incorporated in mussel shells could be used to identify population sources (i.e. collection locations), we assessed the geographic variation in shell chemistry of blue mussels collected from seven populations between Cape Cod, Massachusetts and northern Maine. Across this ∼500 km of coastline, we were able to successfully predict population sources for over two-thirds of juvenile individuals, with almost 80% of juveniles classified within one site of their collection location and 97% correctly classified to region. These results indicate that significant differences in elemental signatures of mussel shells exist between open-coast sites separated by ∼50 km throughout the Gulf of Maine. Our findings suggest that elemental “fingerprinting” is a promising approach for predicting redistribution potential of the blue mussel, an ecologically and economically important species in the region.     

Septum volume and food‐storing behavior are related in parids

The hippocampal formation (HF) of food‐storing birds is larger than non‐storing species, and the size of the HF in food‐storing Black‐Capped Chickadees (Poecile atricapillus) varies seasonally. We examined whether the volume of the septum, a medial forebrain structure that shares reciprocal connections with the HF, demonstrates the same species and seasonal variation as has been shown in the HF. We compared septum volume in three parid species; non‐storing Blue Tits (Parus caeruleus) and Great Tits (Parus major), and food‐storing Black‐Capped Chickadees. We found the relative septum volume to be larger in chickadees than in the non‐storing species. We also compared septum and nucleus of the diagonal band (NDB) volume of Black‐Capped Chickadees at different times of the year. We found that the relative septum volume varies seasonally in food‐storing birds. The volume of the NDB does not vary seasonally. Due to the observed species and seasonal variation, the septum, like the hippocampal formation of food‐storing birds, may be specialized for some aspects of food‐storing and spatial memory. © 2002 Wiley Periodicals, Inc. J Neurobiol 51: 215–222, 2002     

Role of different lymphoid tissues in the initiation and maintenance of DNA-raised antibody responses to the influenza virus H1 glycoprotein.

Antibody responses in mice immunized by a single gene gun inoculation of plasmid expressing the influenza virus H1 hemagglutinin and in mice immunized by a sublethal H1 influenza virus infection have been compared. Both immunizations raised long-lived serum responses that were associated with the localization of antibody-secreting cells (ASC) to the bone marrow. However, the kinetics of these responses were 4 to 8 weeks slower in the DNA-immunized than in the infection-primed mice. Following a gene gun booster, the presence of ASC in the inguinal lymph nodes, but not in other lymph nodes, revealed gene gun responses being initiated in the nodes that drain the skin target site. Both pre- and postchallenge, the DNA-immunized mice had 5- to 10-times-lower levels of antibody and ASC than the infection-primed mice.     

Presence of single-stranded DNA in PCR products of slow electrophoretic mobility.

PCR products were characterized by electrophoresis, blotting and hybridization. In addition to the bands of expected size, bands of slower electrophoretic mobility were often detected. The slower bands completely disappeared when the PCR products were subjected to slow cooling, treated with S1 nuclease or run on an alkaline gel, whereas the bands of expected size were unaffected. The slower bands are therefore likely to contain single-stranded DNA.     

Inactivation of the proteolytic activity of mouse nerve growth factor by human C1(activated)-inhibitor

The interaction between the serine protease gamma subunit of NGF (gamma-NGF) and human C1(activated)-inhibitor (C1-Inh) has been studied. C1-Inh inactivates the protease activity of gamma-NGF as measured by its ability to cleave the synthetic substrate benzoyl-arginine-p-nitroanilide (L-BAPNA). Experiments in which gamma-NGF and C1-Inh were mixed at differing molar ratios indicated that inhibition was due to the formation of a 1:1 stoichiometric complex. Analysis of the interaction of 125I-labeled gamma-NGF with C1-Inh by SDS-PAGE and autoradiography indicated that a covalent bond was formed between gamma-NGF and C1-Inh. The covalent bond was hydrolyzed by hydroxylamine, which suggested that the two proteins were linked via an acyl linkage. The formation of this complex was time dependent and required the proteolytic activity of the gamma-NGF.     

Sea urchin oocytes possess elaborate cortical arrays of microfilaments, microtubules, and intermediate filaments

Extensive arrays of microfilaments, microtubules and cytokeratin-type intermediate filaments were detected in the cortex of Strongylocentrotus droebachiensis oocytes using fluorescently labeled antibodies on both cortex and whole mount preparations. All three filament systems undergo dramatic structural reorganization during meiotic maturation of the egg. Microfilaments form a dense meshwork within the cortex of the oocyte. After meiosis, the filaments rearrange and shorten, resulting in a more loosely organized network. Both cortical microtubules and microtubules associated with a microtubule-organizing center are observed within the oocyte. After meiosis, the number and length of the cortical microtubules gradually diminish. A microtubule organizing center is found situated between the germinal vesicle and the plasma membrane in many oocytes. A network of filaments extends from the microtubule organizing center and radiates peripherally toward the germinal vesicle, presumably marking the animal pole. Cytokeratin-like intermediate filaments form a reticular network within the oocyte cortex, then solubilize during meiosis. In whole mounts of oocytes there is a single focal center of cytokeratin staining from which filaments radiate. Indirect immunofluorescence experiments, using anti-tubulin and anti-cytokeratin antibodies simultaneously, reveal the intermediate filament focal center to be localized within the microtubule organizing center. These results demonstrate the presence of a complex cortical cytoskeleton in premeiotic eggs of the sea urchin, Strongylocentrotus droebachiensis.