摘要:

We have isolated a new semidominant clock mutantTokion the second chromosome inDrosophila melanogaster. This mutant differs from the wild-typeCanton-Sin several properties as follows. Larger values are obtained in the phase angle difference (ψ, the time from lights-off in a 24-hr light-dark cycle to an activity offset), the ratio of activity time to rest time (α/ρ) and the activity level. The free-running period (τ) is 25.3 hr, one hour longer than in the wild-type. In the phase response curve (PRC), the ratio between the delay and the advance portion is larger and the cross-over point occurs later, although there is no difference in amplitude of the mutant's PRC (Type I). The rhythm is more sensitive to the light intensity, becoming obscure in darker condition.Tokiinteracts with other clock mutations,perS, perLandAnd, in such a way thatτs associated with these three X-linked mutations are lengthened andψvalues become smaller.

ISSN:0167-7063    

DOI:10.3109/01677069409167276

出版商:Taylor&Francis    

年代:1994

数据来源: Taylor

摘要:

The number of synaptic contacts formed by a neuron is known to vary with its surface area. This could be because large neurons are able to establish more synaptic sites, or because those neurons that are able to establish more sites are subsequently able to enlarge. To test between these two possibilities clones of enlarged ommatidia were generated in the retina of theDrosophilamutantgigas, by mitotic recombination followingγ-irradiation in the third-instar larva. The numbers of afferent synaptic contacts formed by the photoreceptor terminals in the first optic neuropil, or lamina, were then counted in the adult. The terminals of mutant photoreceptors were also enlarged, but by varying degrees. The sizes of their profiles in single sections merged with the size distribution of terminals having a wild-type phenotype, lying outside the clone in the same lamina. A perimeter of 6.0μm for the profiles of receptor terminal in cross section was established as a criterion for distinguishing between normal and mutant phenotypes. The mutant terminals had more presynaptic sites. Because only thegigasterminals are mutant and because they enlarged at a time long before synapse formation occurred in the lamina we may conclude that cell enlargement preceded elevated synaptic number. The increase in synaptic number roughly matched the increased membrane surface of the terminals, so as nearly to preserve a constant areal density of synaptic sites over a 5-fold range in synaptic frequency.

ISSN:0167-7063    

DOI:10.3109/01677069409167277

出版商:Taylor&Francis    

年代:1994

数据来源: Taylor

摘要:

Therpa(receptor potential absent) mutation of the blowfly,Calliphora erythrocephala, reduces the light-evoked responses of photoreceptor cells and renders the fly blind. This phenotype is similar to the phenotype caused bynorpAmutations inDrosophilawhich have been shown to occur within a gene encoding phospholipase C. In Western blots,norpAantiserum stains a protein in homogenates of wild-typeCalliphoraeye and head that is similar in molecular weight to thenorpAprotein. Very little staining of this protein is observed in similar homogenates ofrpamutant. Moreover,norpAantiserum strongly stains retina in immunohistochemical assays of wild-type adult head, but not inrpamutant. Furthermore, eyes ofrpamutant have a reduced amount of phospholipase C activity compared to eye of wild-typeCalliphora. These data suggest that therpamutation occurs in a phospholipase C gene of the blowfly that is homologous to thenorpAgene ofDrosophila.

ISSN:0167-7063    

DOI:10.3109/01677069409167278

出版商:Taylor&Francis    

年代:1994

数据来源: Taylor

摘要:

Visual flight control is studied in three mutant alleles of the geneellipsoid body open(ebo) ofDrosophila melanogaster. In mutanteboflies the central complex is disturbed to varying degrees. Defects range from a small opening in the ellipsoid body to the dissociation of the ring into two parts, a cleft in the fan-shaped body and hypoplasia in the protocerebral bridge. Other parts of the brain are not visibly affected. Flight behavior is normal with respect to the amplitude of the optomotor response and to the object response (single rotating stripe). A reduced amplitude in the small random oscillations of the torque trace (yaw torque activity), however, is found in all three alleles. In two of them the frequency of torque spikes is reduced. In the alleleebo678the dynamics of the optomotor response is altered. Upon reversal of the direction of rotation mutant flies take longer than wild type to shift their yaw torque to the new response level (optomotor reversal time). Finally, these flies also behave abnormally in the flight simulator in which their yaw torque controls the angular velocity of the panorama. Manyebo678flies fixate a single stripe less persistently than normal flies, some even trying to fly away from it (antifixation). Inebo678gynandromorphs the four behavioral phenotypes (“yaw torque activity”,“torque spike frequency”,“on-target fixation”and“optomotor reversal time”) are all highly correlated with the phenotype of the ellipsoid body. Yaw torque activity and torque spike frequency in addition are correlated with the phenotype of the thorax suggesting that these behavioral defects are in part caused by mutant influences on the ventral ganglion. The results support the hypothesis that the central complex is involved in the control of flight behavior.

ISSN:0167-7063    

DOI:10.3109/01677069409167279

出版商:Taylor&Francis    

年代:1994

数据来源: Taylor