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D R Kankel

Publications and source records attributed to D R Kankel.

18 recordsLinked to original sources
PubMed1993

Enhancer detector analysis of the extent of genomic involvement in nervous system development in Drosophila melanogaster.

We conducted a survey of the patterns of gene expression in the central nervous system (CNS) of larvae of the fruitfly Drosophila melanogaster to identify genes that may be important in the development of the CNS, aid in the recognition of basic organizing features that might underlie CNS development, and estimate the extent of the use of information encoded in the genome in the construction of the nervous system. A so-called enhancer detector strategy was used to generate many thousands of lines containing a beta-galactosidase reporter gene. These lines were screened as third-instar larvae for patterns of expression in the developing optic lobes and other portions of the CNS. Most of the lines recovered which evidence staining within the CNS could be included in one of a relatively small number of patterns. A random sample of 594 lines from the larger population screened was selected to quantify the relative frequencies of these patterns, and a more careful analysis of the changes in the patterns of expression with developmental time was done for representative lines of nine of the patterns. These studies demonstrated great variability in the pattern of gene expression as a function of developmental stage. Few, if any, lines showed beta-galactosidase activity limited to the optic lobes; similarly, few lines were identified in which staining was limited to only a small number of cells. Together with the limited number of patterns of gene expression seen, this suggests that in the larval CNS developmental pathways may be controlled by a combinatorial process of gene activity that involves the majority of the genome rather than by having a specific gene specify the fate of only a few neuronal precursors.

Animals↗
PubMed1992

The l(1)ogre gene of Drosophila melanogaster is expressed in postembryonic neuroblasts.

Previous genetic studies showed that the wild-type function of the lethal (1) optic ganglion reduced (l(1)ogre) gene in Drosophila melanogaster was needed, apparently specifically, for the generation and/or maintenance of postembryonic neuroblasts, i.e., those neuroblasts in the optic formation centers (primordia of the adult optic lobes) and giant neuroblasts scattered over the periphery of cortices of the larval central nervous system (CNS). In the present study temporal and spatial specificity of l(1)ogre expression was investigated by in situ hybridization and also immunofluorescence with polyclonal anti-l(1)ogre antibodies. l(1)ogre protein was detected, as expected, in the optic formation centers and giant neuroblasts in the larval CNS. l(1)ogre expression, however, was not specific to these neuroblasts: expression was also detected in a wide range of tissues including the CNS at many developmental stages. Examination of transcriptional pattern indicates that l(1)ogre is expressed in derivatives of the ectoderm, endoderm, and mesoderm (but not in the germ line) in two developmental contexts: (i) during and shortly after the proliferative phase and (ii) during histolysis of some larval tissues.

Amino Acid Sequence↗
PubMed1992

l(1)trol and l(1)devl, loci affecting the development of the adult central nervous system in Drosophila melanogaster.

Adult optic lobes of Drosophila melanogaster are composed of neurons specific to the adult which develop postembryonically. The structure of the optic lobes and aspects of its development have been described, and a number of mutants that affect its development have been identified. The focus of every screen to date has been on disruption of adult structure or function. Although these loci were originally identified on the basis of viable mutants, some have proven capable of giving rise to lethal alleles. It seems reasonable to assume that mutants which strongly affect development of the imaginal-specific central nervous system may evidence abnormalities during the late larval or pupal stages when the adult central nervous system is undergoing final assembly and might show a lethal phase prior to eclosion (as is true for mutations at the previously defined l(1)ogre locus). We have carried out the first screen of autosomal and sex-linked late larval and pupal lethals to identify mutations that affect the development of the optic lobes. Our screen yielded nine mutants that could tentatively be grouped into three classes, depending on the neuroblast population affected and imaginal disc phenotypes. Two of these, including one that is allelic to l(1)zw1, were chosen for further analysis.

Animals↗
PubMed1992

Mosaic analysis gives an estimate of the extent of genomic involvement in the development of the visual system in Drosophila melanogaster.

To investigate the role of vital loci in the development of the visual system of Drosophila, we induced mitotic recombination in individuals heterozygous for recessive organismal lethals and selected for analysis the resulting mosaics with homozygous mutant eye clones. Heads bearing clones were serially sectioned, silver-stained and examined for aberrations in the ommatidia and the neural structures to which they project. In our screen of 68 lines bearing diepoxybutane-induced X-linked lethals, 26 yielded few or no homozygous mutant clones (putative cell-lethals). Of the rest, 20 lines produced individuals with morphologically abnormal eye clones showing various degrees of aberrations in the ommatidial architecture. In 14 of these 20, the laminar cartridges innervated by the mutant clones were also disorganized. Clones with normal structure were found in 18 of the lines, and three lines were resistant to the induction of mitotic recombination. In a single line, comparatively normal clones in the eye projected to a lamina with subtle but consistent abnormalities. To the extent that we have a representative sample, these results suggest that about two-thirds of all vital genes may be essential for the normal assembly and neural connectivity of the eye. This points to a high degree of pleiotropy in the manner in which information in the genome of the fly is used in development.

Animals↗
PubMed1990

Molecular cloning and analysis of l(1)ogre, a locus of Drosophila melanogaster with prominent effects on the postembryonic development of the central nervous system.

Previous genetic studies have shown that wild-type function of the l(1)ogre (lethal (1) optic ganglion reduced) locus is essential for the generation and/or maintenance of the postembryonic neuroblasts including those from which the optic lobe is descended. In the present study molecular isolation and characterization of the l(1)ogre locus was carried out to study the structure and expression of this gene in order to gain information about the nature of l(1)ogre function and its relevance to the development of the central nervous system. About 70 kilobases (kb) of genomic DNA were isolated that spanned the region where l(1)ogre was known to reside. Southern analysis of a l(1)ogre mutation and subsequent P element-mediated DNA transformation mapped the l(1)ogre+ function within a genomic fragment of 12.5 kb. Northern analyses showed that a 2.9-kb message transcribed from this 12.5-kb region represented l(1)ogre. A 2.15-kb portion of a corresponding cDNA clone was sequenced. An open reading frame (ORF) of 1,086 base paris was found, and a protein sequence of 362 amino acids with one highly hydrophobic segment was deduced from conceptual translation of this ORF.

Amino Acid Sequence↗
PubMed1988

On the role of normal acetylcholine metabolism in the formation and maintenance of the Drosophila nervous system.

We have examined the requirement for normal acetylcholine metabolism in the formation and maintenance of the larval and adult central nervous system in Drosophila melanogaster. By using mutations at the Ace and Cha loci, which respectively encode the degradative and synthetic enzymes for acetylcholine (ACh), acetylcholinesterase (AChE), and choline acetyltransferase (ChAT), we have been able to disrupt acetylcholine metabolism in situ. An ultrastructural analysis of embryonic nervous tissue lacking either enzymatic function has indicated that while neither function is required for the formation of the larval central nervous system, each is required for the subsequent maintenance of its structural integrity and function. Using temperature sensitive mutations at the Cha locus, the normal developmental profile of ChAT activity during the late larval and pupal stages was disrupted. Subsequent examination of the morphology and behavior of the treated animals has indicated that normal acetylcholine metabolism is not required for the initial formation of the adult nervous system, but is required for the subsequent maintenance of its structural integrity and function. The results obtained in these studies are discussed with respect to data presented on the adult distribution of the cholinergic markers' AChE activity and ChAT immunoreactivity. The projections of adult peripheral neurons innervating Ace+ tissue from Ace cuticular clones has been examined to address the nature of the structure of Ace neuropil. Normal projections are apparently achieved and maintained, suggesting that the defects seen in adult Ace mosaics arise as an aberrant intracellular organization of morphologically normal cells.

Acetylcholine↗
PubMed1987

A genetic analysis of glutamatergic function in Drosophila.

Neurotransmitters are essential for communication between neurons and hence are vital in the overall integrative functioning of the nervous system. Previous work on acetylcholine metabolism in the fruit fly, Drosophila melanogaster, has also raised the possibility that transmitter metabolism may play a prominent role in either the achievement or maintenance of the normal structure of the central nervous system in this species. Unfortunately, acetylcholine is rather poorly characterized as a neurotransmitter in Drosophila; consequently, we have begun an analysis of the role of glutamate (probably the best characterized transmitter in this organism) in the formation and/or maintenance of nervous system structure. We present here the results of a series of preliminary analyses. To suggest where glutamatergic function may be localized, an examination of the spatial distribution of high affinity [3H]-glutamate binding sites are presented. We present the results of an analysis of the spatial and temporal distribution of enzymatic activities thought to be important in the regulation of transmitter-glutamate pools (i.e., glutamate oxaloacetic transaminase, glutaminase, and glutamate dehydrogenase). To begin to examine whether mutations in any of these functions are capable of affecting glutamatergic activity, we present the results of an initial genetic analysis of one enzymatic function, glutamate oxaloacetic transaminase (GOT), chosen because of its differential distribution within the adult central nervous system and musculature.

Animals↗
PubMed1985

Specificity of gene action during central nervous system development in Drosophila melanogaster: analysis of the lethal (1) optic ganglion reduced locus.

A newly defined genetic locus designated lethal (1) optic ganglion reduced (l(1)ogre: 1-18.8, 6E1/2-6E4/5) is characterized. Four alleles have been isolated, one organismal viable and three organismal lethals. Histological analyses of these mutants at the light microscopic level have detected defects only in the developing and adult central nervous system (CNS). Examination of genetic mosaics suggests that the wild-type product of this locus may function specifically in the CNS. Analyses of staged material show that abnormalities first become apparent early in the larval period, indicating that the l(1)ogre+ gene product normally acts at or before this stage. No maternal effects were detectable. Determination of the temperature-sensitive period for lethality, of a temperature-sensitive heteroallelic combination, indicates that the l(1)ogre+ gene product also acts late in the larval period. These results show that the time of l(1)ogre+ gene action overlaps the period during which growth and assembly of the imaginal CNS occurs and are consistent with the hypothesis that l(1)ogre may act specifically in the imaginal CNS during its morphogenesis.

Alleles↗
PubMed1985

Developmental interactions between the peripheral and central nervous system in Drosophila melanogaster: analysis of the mutant, two-faced.

A genetically complex mutant, two-faced (tfd), which causes the production of extra eye and antennal tissue on the dorsal head cuticle, has been analyzed for connectivity to and projection patterns in the central brain of nerves derived from these extra structures. It has been found that the extra antennal nerves frequently connect to and achieve normal projections in the brain, whereas no convincing connectivity between the nerves from the extra eye tissue and the brain, has been found. This suggests that the mechanisms by which the nerves derived from normal eyes and antennae achieve central connections may differ.

Animals↗
PubMed1983

Golgi and genetic mosaic analyses of visual system mutants in Drosophila melanogaster.

We have used a Golgi staining procedure in Drosophila melanogaster to examine the structure of individual neurons in the visual systems of the Canton-S wild-type strain, of flies expressing mutations at the Glued, rough, glass, and uneven loci, all of which affect the organization of the visual system, and of genetic mosaics involving the Glued and uneven loci. We have found that the structure of the neurons studied in the wild type is quite similar to that reported for other diptera and that the mutants studied evidence a variety of abnormalities in neuronal morphology, each mutant being characterized by a different spectrum of aberrations. The genetic mosaic analysis of the Glued and uneven loci showed that the structure of individual neurons in the optic lobes is profoundly influenced by the genotype of the cells projecting to that region from the compound eye but that the final form attained by a neuron is not solely controlled by that factor.

Animals↗
PubMed1983

Analysis of visual system development in Drosophila melanogaster: mutations at the Glued locus.

We have analyzed several aspects of the development of flies carrying mutations at the Glued locus. Optic lobe abnormalities in individuals heterozygous for the original Glued allele were previously shown to result from an action of this mutation in the retinula cells. We have estimated when the functioning of this gene or its product is required for normal visual system development by using genetic mosaicism induced by somatic recombination and temperature shifts of a temperature-sensitive mutation at this locus. Both methods point to a period in the mid-third instar, suggesting that early events in the formation of ommatidia and/or late events in the program of retinal cells are affected. Application of a new histological stain for developing axons indicates that individuals heterozygous for Glued exhibit abnormalities in the retinula fiber projection by the late third instar. Thus, the adult phenotype is not solely the result of later cellular degeneration or rearrangement. Beneath M+ Gl+ clones which encompass the entire eye were found optic lobe abnormalities with features not seen in either other mosaics or Gl heterozygotes. The possibility that these abnormalities result from temporal asynchrony in the development of eye and and optic lobe in these individuals is discussed and the results of attempts to test this hypothesis are presented.

Age Factors↗
PubMed1976

Genetics of acetylcholinesterase in Drosophila melanogaster.

Genes in Drosophila melanogaster that control acetylcholinesterase (AChE) were searched for by segmental aneuploidy techniques. Homogenates of flies containing duplications or deletions for different segments were assayed for enzyme activity. A region on the third chromosome was found for which flies having one dose consistently gave lower AChE activity than euploid flies, which in turn had lower activity than flies with three doses. The activity differences were in the approximate ratio 1:2:3. Fine structure deletion mapping within this region revealed a very small segment for which one-dose flies have approximately half-normal activity. To obtain putative AchE-null mutations, lethal mutations within this region were assayed. Four allelic lethals have approximately half-normal activity in heterozygous condition. These lethals probably define the structural locus (symbol: Ace) for AchE.

Acetylcholinesterase↗
PubMedDate not supplied

Genetic analysis of mutations at the Glued locus and interacting loci in Drosophila melanogaster.

A genetic analysis of the dominant mutation Glued that perturbs the development of the normal axonal architecture of the fly's visual system was undertaken. Ten new alleles at this locus were identified and characterized. Two complementation groups that were identified failed to complement the original allele, suggesting that it is a double mutant or that it resides at a complex locus. Several of the new alleles display visual-system abnormalities similar to those of the original mutation. Seven of the eight members of one complementation group are embryonic/early larval lethals, like the original mutation. The other allele in this group is temperature sensitive. Homozygous mutant adults exhibit a temperature-sensitive female sterile phenotype. Unsuccessful attempts to recover genetic mosaics carrying clones of cells homozygous for some of these mutations revealed that they are either essential for the viability of individual cells or that they affect some other fundamental cellular function, such as mitosis or the ability to participate in tissue level organization, which prevents them from being recovered in adult mosaics. This also indicates that these mutations do not specifically affect neural cells. A number of X-ray- and EMS-induced partial and complete phenotypic "revertants" of the original allele have also been isolated as material for comparative analysis of visual system development. All "revertants" that alter the abnormal eye phenotype towards the wild type have similar impact on the organization of the optic lobe.

Animals↗