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1993 (1)
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1Author    M. Heisenberg, K. BöhlRequires cookie*
 Title    Isolation of Anatomical Brain Mutants of Drosophila by Histological Means  
 Abstract    Due to its small size D rosophila m elanogaster can conveniently be used in screening experiments for anatomical brain mutants. A simple method has been designed which allows to process up to 20 identifiable flies as a single preparation in a standard histology routine. Anatomical brain mutants are very frequent. Over 60 mutants were obtained from the inspection of about 3000 brains. So far genetic variations of brain structure fall into 4 classes: (1) "low fidelity" mutants in which brains are less precisely built; (2) "brain shape" mutants with globally or partially reduced brains; (3) "architectonic" mutants which show constructional defects mainly in the repetitive structures of the brain and (4) "vacuolar" mutants with globular "holes" in certain areas of the brain. These mutant classes obviously reflect different aspects of brain development like cell pro­ liferation (2), "wiring" (3) and cell death (4). Some of the mutants may prove to be useful in anatomical, physiological or genetic brain research. 
  Reference    Z. Naturforsch. 34c, 143 (1979); received November 18 1978 
  Published    1979 
  Keywords    Brain, Anatomy, Development, Mutants, D rosophila 
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 TEI-XML for    default:Reihe_C/34/ZNC-1979-34c-0143.pdf 
 Identifier    ZNC-1979-34c-0143 
 Volume    34 
2Author    V. A. Boichenko, V. V. Klimovb, S. R. Mayes3, J. Barber1, T. Echnology, M. Edicine, London Sw, A. Y., U. K.Requires cookie*
 Title    Characterization of the Light-Induced Oxygen Gas Exchange from the IC 2 Deletion Mutant of Synechocystis PCC 6803 Lacking the Photosystem II 33 kDa Extrinsic Protein  
 Abstract    The absence o f the extrinsic M n-stabilizing 33 kD a protein in the IC 2 mutant o f Synecho­ cystis PCC 6803 disturbs the redox cycling o f the water splitting system and retards the formation o f its higher S-states (I. Vass, K.. We have performed analyses o f the flash-induced oxygen exchange in the mutated cyanobacterium to clarify further the role o f the 33 kD a protein. Under aerobic conditions, both the wild type and IC2 mutant show a relative­ ly slow signal o f oxygen rise on the first flash which is increased about twice by the addition o f 10 (aM D C M U and significantly diminished by lowering the oxygen concentration in the medi­ um. According to action spectra measurements, this m ode o f apparent oxygen release is me­ diated by PS I and can be attributed to a light induced inhibition o f respiratory activity. In contrast to the wild type, having the usual oxygen evolution flash pattern with a periodicity o f four, the IC2 mutant shows a binary oscillation pattern o f flash-induced respiratory oxygen exchange at a flash frequency 10 Hz, being dampened with D C M U or by a lower flash fre­ quency (< 1 Hz). Oxygen evolution due to water splitting is clearly seen in the IC2 mutant when background far-red illumination is applied to saturate the signal due to respiratory inhi­ bition, but a quadruple oscillatory com ponent o f flash-induced oxygen evolution appears only in the presence o f artificial electron acceptors under partial aerobic conditions. The mutant possesses a higher PS I/PS II ratio compared to the wild type, as judged from both the flash-induced yields and quantum efficiencies o f the steady-state rates o f the oxygen exchange reac­ tions. Estimates o f antenna sizes indicate about a 20% decrease o f optical cross-section at 675 nm o f the PS II unit in IC 2 mutants in comparison with the wild type. It is suggested that the absence o f the 33 kDa protein leads to a m odification o f the PS II assembly and because o f the slowing down o f the S-state cycle, the rate o f cyclic electron flow around PS II is enhanced. It seems that the absence o f the 33 kD a protein in Synechocystis 6803 also disturbs energy transfer between adjacent PS II core complexes and may also alter their association with the phycobilisomes. 
  Reference    Z. Naturforsch. 48c, 224—201 (1993); received December 10 1992 
  Published    1993 
  Keywords    Photosystem II, Oxygen Evolution, 33 kD a Protein, Synechocystis, Mutants 
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 TEI-XML for    default:Reihe_C/48/ZNC-1993-48c-0224.pdf 
 Identifier    ZNC-1993-48c-0224 
 Volume    48 
3Author    Joseph Hirschberg, NirO. Had, Iris Pecker, Ana RahatRequires cookie*
 Title    Isolation and Characterization of Herbicide Resistant Mutants in the Cyanobacterium Synechococcus R2  
 Abstract    Departm ent o f G en etics, The H ebrew University o f Jerusalem. Jerusalem. A variety of mutants which are resistant to triazine — and urea — classes of herbicides have been isolated in the cyanobacterium Synechococcus R 2. A ll the mutants that have been analyzed, show som e cross-resistance to different herbicides suggesting that these herbicides share a com m on binding site in photosystem II. Three psbA genes have been identified in Synechococcus R 2. The /« M -c o p y I gene was cloned from three mutants and used in D N A -m ed iated genetic transformation. It was found that in all three mutants this gene could transfer the mutation for herbicide resistance indicating that this gene codes for the herbicide resistant protein. 
  Reference    Z. Naturforsch. 42c, 758—7 (1987); received January 7 1987 
  Published    1987 
  Keywords    H erbicide Resistance, psb A G en e, Photosystem II, Cyanobacteria, Mutants 
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 TEI-XML for    default:Reihe_C/42/ZNC-1987-42c-0758.pdf 
 Identifier    ZNC-1987-42c-0758 
 Volume    42