Search results for "Nephropidae"
showing 5 items of 15 documents
Small-signal analysis of the encoder mechanism in the lobster stretch receptor and the frog and cat muscle spindle.
1975
Ausgehend von der Leitwert-Potential-Beziehung als Bedingung fur die Impulsauslosung an erregbaren Membranen (Chaplain, 1974) wird eine Kleinsignal-Analyse des Kodierungsvorganges in Mechanorezeptoren beschrieben. Hierbei wird die Theorie der Systeme mit zeitvariablen Parametern angewendet. Das beschriebene mathematische Modell erlaubt quantitative Aussagen fur den Frequenzgang unabhangig davon ob die Momentafrequenz oder die Impulsdichte als Ausgangssignal betrachtet wird. Die Approximation experimenteller Daten gelingt sowohl fur die Ansteuerung des Kodierers bei intrazellularer Stromstimulierung im Fall des Dehnungsrezeptors wie auch durch Leitwertanderungen als Folge des mechano-elektri…
Influence of antibody binding on oxygen binding behavior of Panulirus interruptus hemocyanin
1997
Oxygen binding behavior of monomeric subunit a and the hexameric form of this subunit of hemocyanin of Panulirus interruptus is influenced by the binding of various monoclonal antibodies. These antibodies react with other surface parts of the subunit than its second domain in which the oxygen binding site is located. The influence of three monoclonal antibodies and their antigen binding fragments (F-ab) has been investigated. Two antibodies increase the oxygen affinity of monomeric hemocyanin from that observed in its low affinity T-state, while the third has little influence on this property. F-ab fragments abolish almost completely the cooperativity of oxygen binding by the hexameric hemo…
Allosteric Models for Multimeric Proteins: Oxygen-Linked Effector Binding in Hemocyanin
2005
In many crustaceans, changing concentrations of several low molecular weight compounds modulates hemocyanin oxygen binding, resulting in lower or higher oxygen affinities of the pigment. The nonphysiological effector caffeine and the physiological modulator urate, the latter accumulating in the hemolymph of the lobster Homarus vulgaris during hypoxia, increase hemocyanin oxygen affinity and decrease cooperativity of oxygen binding. To derive a model that describes the mechanism of allosteric interaction between hemocyanin and oxygen in the presence of urate or caffeine, studies of oxygen, urate, and caffeine binding to hemocyanin were performed. Exposure of lobster hemocyanin to various pH …
Molecular cloning and evolution of lobster hemocyanin.
2001
In the American lobster, Homarus americanus, oxygen is transported by a hemocyanin that is composed 2 x 6 subunits. N-terminal sequencing show the presence of three distinct subunit types (alpha, beta and gamma). We cloned the cDNA of one of these subunits that belong to the alpha-type. It encodes a hemocyanin subunit of 654 amino acids with a molecular mass of 84.8 kDa, which is synthesized in the hepatopancreas. Phylogenetic analyses of the crustacean hemocyanin sequences show two well-separated clades, which correspond to the alpha and gamma-type subunits. Sequences of beta-type subunits are still unknown. The gamma-sequences have evolved about 15% faster than the alpha-subunits, consist…
A STUDY OF POPULATION GENETICS IN THE EUROPEAN LOBSTER, HOMARUS GAMMARUS (DECAPODA, NEPHROPIDAE)
2001
By means of an RAPD analysis, the degree of genetic variation in the European lobster, Homarus gammarus, was assessed. We focused our attention on the Helgoland population, which is isolated by its geographical location. By comparison with seven other European lobster populations we demonstrated that the Helgoland lobster is genetically widely separated from other European lobster stocks. However, all populations investigated showed high values of genetic distance, indicating that genetic exchange among European populations of Homarus gammarus may be restricted. The European lobster populations appeared to be isolated by distance since the pattern of genetic relationships reflects their geo…