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'Pattern Formation' in keywords Facet   section ZfN Section C  [X]
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1Author    Hans MeinhardtRequires cookie*
 Title    Cooperation of Compartments for the Generation of Positional Information  
 Abstract    A mechanism is proposed for pattern formation in developmental subfields. In application to imaginal disks, the compartmentalization appears as a prerequisite for the generation of posi­ tional information in the proximo-distal dimension. Cooperation of three or four compartments in the production of a morphogen leads to a cone-shaped morphogen distribution, since a high production rate of the morphogen is possible only at the intersection of compartment borders. The local concentration of the cone-shaped distribution is a measure for the distance from this center and can be used as positional information. In agreement with the experimental observa­ tions, the model predicts that (i) the distalmost structures are formed at the intersection of compartment borders; (ii) distal transformation occurs whenever cells of all compartments come close to each other; (iii) distal transformation does not require a complete set of circumferential structures; (iv) mutants exist in which the positional information and not the response of the cells is altered and (v) no distal to proximal intercalation of missing leg segments occur. Regeneration and formation of supernumerary insect legs can be explained as well. Simple molecular reaction can account for this type of pattern formation. The "complete circle rule" of French, Bryant and Bryant (Science 193,969-981 (1976)) for distal transformation may be simplified by a "coopera­ tion of compartments" rule. 
  Reference    Z. Naturforsch. 35c, 1086—1091 (1980); received July 21 1980 
  Published    1980 
  Keywords    Positional Information, Imaginal Disk, Compartments, Pattern Formation 
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 TEI-XML for    default:Reihe_C/35/ZNC-1980-35c-1086.pdf 
 Identifier    ZNC-1980-35c-1086 
 Volume    35 
2Author    Rainer Gilles, Lothar JaenickeRequires cookie*
 Title    Differentiation in Volvox carteri: Study of Pattern Variation of Reproductive Cells  
 Abstract    Asexual spheroids of the multicellular green alga Volvox are composed o f two types o f cells: non-flagellated reproductive gonidia and Chlamydomonas-\ike flagellated somatic cells. They are committed by a differentiating cleavage during embryogenesis. The gonidia o f the adult spheroids form a symmetrical pattern consisting o f four layers o f four gonidia each; their position is established already in the embryos by the gonidial initials. Whereas, generally, the 16-gonidia pattern is assumed to be the basic one, most o f the spheroids have fewer gonidia (down to 8). The nine possible gonidial patterns (8 to 16 gonidia) are described and correlated to the gonidial stem cells which have been differentiated. Defects in gonidial pattern are o f particular interest, since any model of differentiation has to explain not only the basic pattern formed, but also its systematic variations. Our study shows that the pattern reduction is by no means random, but governed by an intrinsic mechanism which shifts the first unequal cleavage from the 32-celled stage to the 16-celled stage. All the patterns formed can be deduced from cleavage pathways involving non-synchronous differentiation of the stem cells. Thus, pattern formation can be correlated to timing and spacing signals regulating events during embryogenesis. 
  Reference    Z. Naturforsch. 37c, 1023—1030 (1982); received June 1 1982 
  Published    1982 
  Keywords    Volvox carteri, Differentiation, Embryogenesis, Cell Lineages, Pattern Formation 
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 TEI-XML for    default:Reihe_C/37/ZNC-1982-37c-1023.pdf 
 Identifier    ZNC-1982-37c-1023 
 Volume    37 
3Author    Rudolf WinklbauerRequires cookie*
 Title    Growth Control and Pattern Regulation in the Lateral Line Systems of Xenopus  
 Abstract    In Xenopus, the supraorbital lateral line system consists of a periodic pattern of lateral line organs which is formed by the regular fragmentation of a streak-like primordium. The pattern forming mechanism which subdivides the primordium into individual organs is not capable of adjusting to the variable size of the system. Nevertheless, the number of organs per supraorbital system tends to be held constant. This is achieved by regulating the growth of the system in an appropriate manner. 
  Reference    Z. Naturforsch. 43c, 294—300 (1988); received December 22 1987 
  Published    1988 
  Keywords    Growth Control, Pattern Formation, Lateral Line System Xenopus 
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 TEI-XML for    default:Reihe_C/43/ZNC-1988-43c-0294.pdf 
 Identifier    ZNC-1988-43c-0294 
 Volume    43 
4Author    Stefan Reimann, Rapporteur, JoaquinM. Fuster, Alfred Gierer, Gottfried Mayer-Kress, Titus Neumann, Pieter Roelfsem, Stefan Rotter, Gregor Schöner, Achim Stephan, Eiion Vaadia, Henrik WalterRequires cookie*
 Title    Group Report: Emergent Properties of Natural and Artificial Systems* On the Meanings of Emergence  
  Reference    Z. Naturforsch. 53c, 770—774 (1998); received April 16 1998 
  Published    1998 
  Keywords    Emergence, Pattern Formation, Self-Organization, Pre-Determinism 
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 TEI-XML for    default:Reihe_C/53/ZNC-1998-53c-0770.pdf 
 Identifier    ZNC-1998-53c-0770 
 Volume    53