(n.) A fishlike creature (Amphioxus lanceolatus), two or three inches long, found in temperature seas; -- also called the lancelet. Its body is pointed at both ends. It is the lowest and most generalized of the vertebrates, having neither brain, skull, vertebrae, nor red blood. It forms the type of the group Acrania, Leptocardia, etc.
Example Sentences:
(1) In situ, CaVP forms a high affinity Ca2+-dependent complex with an Mr 36,000 protein present in muscle extracts of amphioxus.
(2) Amphioxus CaVP does not substitute for calmodulin in a specific enzyme assay nor for troponin C in restoring Ca2+ sensitivity to skinned muscle fibers.
(3) Joseph cells, assumed to be photoreceptive organs in amphioxus, were studied by electron microscopy as well as by a histofluorescence technique.
(4) Like proinsulin, amphioxus proILP contains a C-peptide, which is flanked by paired basic residues and is probably removed by proteolysis.
(5) Sequence comparisons show that the amphioxus ILP A and B domains are equally homologous to those of human insulin and IGF-I and -II.
(6) The activities of the creatine-synthesizing enzymes, arginine-glycine transamidinase and guanidinoacetate methylpherase, were not detected in the hagfish or in any of the invertebrates, including those in which creatine was found, with the exception that transamidinase activities were detected in the amphioxus and salt water clam; however, these activities are considered to be artifacts for reasons mentioned in the text.
(7) None of the five epitopes was expressed on amphioxus, nematode, or Dictyostelium MHC.
(8) Crystals of a sarcoplasmic Ca(2+)-binding protein from the protochordate amphioxus have been grown from solutions of ammonium sulfate.
(9) In the Amphioxus genome repetitive and non-repetitive elements are predominantly arranged in a short period interspersion pattern.
(10) A new Ca2+-binding protein, called CaVP, has been detected in muscle of the cephalochordate amphioxus and purified to electrophoretic homogeneity.
(11) Based on these results and the exon-intron organization of the amphioxus ILP gene, we propose that IGF emerged at a very early stage in vertebrate evolution from an ancestral insulin-type gene.
(12) To gain an insight into the molecular changes that accompanied the evolution of vertebrate embryology, and into the relationship between the amphioxus and vertebrate body plans, we have undertaken the first molecular level investigation of amphioxus embryonic development.
(13) The presence of S-antigen in distant species (vertebrates, Amphioxus, nemerteans, annelids, molluscs) indicates a high phylogenetic stability and suggests an important role for this protein in photoreceptor function.
(14) The protochordate amphioxus (Branchiostoma lanceolatum) contains different isoforms of sarcoplasmic, high-affinity Ca2(+)-binding proteins (SCP).
(15) The nervous system of amphioxus tells us little, or nothing, about the ancestral vertebrate system.
(16) It is concluded that two independent mechanisms of ionic permeability increase occur in the membrane of amphioxus muscle cell, one to Na and the other to Ca.
(17) This was also the case with skeletal muscle of prochordate, Amphioxus.
(18) The present study demonstrates for the first time by RIA that LH-RH is present in the heads as well as the bodies of the amphioxuses of both sexes.
(19) Spinal cords of 15 species representing six classes of vertebrates and the protochordate amphioxus were examined with histochemical methods for esterase, ATPase, LDH, PAS, and PAS-phosphorylase.
(20) Its relative abundance in amphioxus muscle indicates that CaVP must underlie an important new limb of Ca2+ regulation in this particular muscle.
Lancelet
Definition:
(n.) A small fishlike animal (Amphioxus lanceolatus), remarkable for the rudimentary condition of its organs. It is the type of the class Leptocardia. See Amphioxus, Leptocardia.
Example Sentences:
(1) Phylogenetic comparisons of 18S ribosomal RNA sequences from two hagfishes, two lampreys, a tunicate, a lancelet, and a number of gnathostomes support the monophyly of the cyclostomes.
(2) The segmented trunk muscle (myotome muscle) of the lancelet (Branchiostoma lanceolatum), a pre-vertebrate chordate, was studied in order to gain information regarding the evolution of excitation-contraction (EC) coupling.
(3) The significance of the presence of rhabdomeric and ciliary photoreceptors in the lancelet brain is discussed.
(4) We have determined the complete sequences of 5S rRNAs from a lamprey (Lampetra reissneri), a lancelet (Branchiostoma belcheri), silkworms (Philosamia cynthia ricini, Bombyx mori, Antheraea pernyi), and a silkworm hybrid (artificially fertilized hybrid species of Philosamia cynthia ricini male x Bombyx mori female), as well as those of cotton seeds (Gossypium hirsutum L.).
(5) Nerve endings of epithalamic, hypothalamic and spinal neurosecretory areas were studied by light and electron microscopy in various vertebrates (from fishes up to mammals) including the lancelet.
(6) A third photoreceptive cell of the lancelet, the lamellate cell, is of ciliary type.