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Cleavage Pattern (cleavage + pattern)
Selected AbstractsSome aspects of spiralian developmentACTA ZOOLOGICA, Issue 1 2010Claus Nielsen Abstract Nielsen, C. 2010. Some aspects of spiralian development. ,Acta Zoologica (Stockholm) 91: 20,28 Spiralian development is not only a characteristic early cleavage pattern, with shifting orientations of the cleavage planes, but also highly conserved cell lineages, where the origin of several organs can be traced back to identifiable cells in the lineage. These patterns are well documented in annelids, molluscs, nemertines, and platyhelminths and are considered ancestral of a bilaterian clade including these phyla. Spiral cleavage has not been documented in ecdysozoans, and no trace of the spiral development pattern is seen in phoronids and brachiopods. Origin of the spatial organization in spiralian embryos is puzzling, but much of the information appears to be encoded in the developing oocyte. Fertilization and "pseudofertilization" apparently provides the information defining the secondary, anterior-posterior body axis in many species. The central nervous system consists of three components: an apical organ, derived from the apical blastomeres 1a111 -1d111, which degenerates before or at metamorphosis; the cerebral ganglia derived from other blastomeres of the first micromere quartet and retained in the adult as a preoral part of the brain; and the originally circumblastoporal nerve cord, which has become differentiated into a perioral part of the brain, the paired or secondarily fused ventral nerve cords, and a small perianal nerve ring. [source] Canine COL1A2 Mutation Resulting in C-Terminal Truncation of Pro-,2(I) and Severe Osteogenesis ImperfectaJOURNAL OF BONE AND MINERAL RESEARCH, Issue 6 2001Bonnie G. Campbell Abstract RNA and type I collagen were analyzed from cultured skin fibroblasts of a Beagle puppy with fractures consistent with type III osteogenesis imperfecta (OI). In a nonisotopic RNAse cleavage assay (NIRCA), the proband's RNA had a unique cleavage pattern in the region of COL1A2 encoding the C-propeptide. DNA sequence analyses identified a mutation in which nucleotides 3991-3994 ("CTAG") were replaced with "TGTCATTGG." The first seven bases of the inserted sequence were identical to nucleotides 4002-4008 of the normal canine COL1A2 sequence. The resulting frameshift changed 30 amino acids and introduced a premature stop codon. Reverse-transcription polymerase chain reaction (RT-PCR) with primers flanking the mutation site amplified two complementary DNA (cDNA) fragments for the proband and a single product for the control. Restriction enzyme digestions also were consistent with a heterozygous mutation in the proband. Type I procollagen labeled with [3H]proline was analyzed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). Increased density of pC-,2(I) suggested comigration with the similarly sized pro-,2(I) derived from the mutant allele. Furthermore, ,-chains were overhydroxylated and the ratio of ,1(I):,2(I) was 3.2:1, consistent with the presence of ,1(I) homotrimers. Analyses of COL1A2 and type I collagen were both consistent with the described heterozygous mutation affecting the pro-,2(I) C-propeptide and confirmed a diagnosis of OI. [source] The hinge region operates as a stability switch in cGMP-dependent protein kinase I,FEBS JOURNAL, Issue 9 2007Arjen Scholten The molecular mechanism of cGMP-dependent protein kinase activation by its allosteric regulator cyclic-3,,5,-guanosine monophosphate (cGMP) has been intensely studied. However, the structural as well as thermodynamic changes upon binding of cGMP to type I cGMP-dependent protein kinase are not fully understood. Here we report a cGMP-induced shift of Gibbs free enthalpy (,,GD) of 2.5 kJ·mol,1 as determined from changes in tryptophan fluorescence using urea-induced unfolding for bovine PKG I,. However, this apparent increase in overall stability specifically excluded the N-terminal region of the kinase. Analyses of tryptic cleavage patterns using liquid chromatography-coupled ESI-TOF mass spectrometry and SDS/PAGE revealed that cGMP binding destabilizes the N-terminus at the hinge region, centered around residue 77, while the C-terminus was protected from degradation. Furthermore, two recombinantly expressed mutants: the deletion fragment ,1-77 and the trypsin resistant mutant Arg77Leu (R77L) revealed that the labile nature of the N-terminus is primarily associated with the hinge region. The R77L mutation not only stabilized the N-terminus but extended a stabilizing effect on the remaining domains of the enzyme as well. These findings support the concept that the hinge region of PKG acts as a stability switch. [source] Laboratory spawning, larval development, and metamorphosis of the limpets Lottia digitalis and Lottia asmi (Patellogastropoda, Lottiidae)INVERTEBRATE BIOLOGY, Issue 1 2002Matthew C. Kay Abstract. This study describes and compares laboratory spawning, larval development, and metamorphosis in the patellogastropod limpets Lottia digitalis and Lottia asmi. Both species were dioecious and freely spawned their gametes, which were fertilized externally. Eggs from L. digitalis and L. asmi averaged 155 and 134 ,m in diameter, respectively. Early cleavage patterns were typical of other patellogastropods. Swimming trochophore larvae had developed , 15 hours after fertilization, and ultimately developed into lecithotrophic veliger larvae that reached metamorphic competence at 5.25,5.5 days after fertilization (13°C). Food particles were frequently visible in the gut of newly metamorphosed individuals one day after settlement, and adult shell growth was typically initiated within 2,4 days of settlement. Small egg size in L. asmi, relative to other eastern Pacific lottiids, may be directly related to the need for high fecundity in this small-bodied species; however, developmental information is available for relatively few lottiid species. Because broadcasting lottiids do not secure egg masses in safe microhabitats for development, this reproductive mode may have been conducive to their ecological radiation into novel habitats. [source] | ||||||||||