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1.
Retinular cells of the compound eyes of stomatopods (mantis shrimps) contain screening pigment granules that migrate radially in response to light. To clarify the role of the cytoskeleton in these movements, we have performed light microscopy and ultrastructural analyses of cytoskeletal organelles in retinular cells. Rhodamine phalloidin staining indicates that filamentous actin is a component of microvillar rhabdomeres and zonula adherens between retinular cells. Ultrastructural studies reveal three populations of microtubules in retinular cells that differ in their orientations and labilities to fixation. Two of these populations are oriented longitudinally in cells: the soma microtubules, found primarily in a column in the cell soma, and the more labile palisade microtubules, which extend alongside the palisade vacuole near the rhabdomere. The third, most labile microtubule population, and filaments 9–30 nm in diameter, are oriented radially in retinular cells, some within cytoplasmic bridges that span the palisade. The radial microtubules and filaments are appropriately oriented for participating in pigment granule migration. Determination of microtubule polarities in retinular cells by decoration with endogenous tubulin indicates that palisade and soma microtubules contain subpopulations having opposite polarity orientations, as has been observed in neuronal dendrites. In contrast, neighboring pigment cells contain microtubules uniformly oriented with minus ends towards the nucleus, as has been observed in most cell types studied. 相似文献
2.
Mating behaviour of red-eyed (wt) and brown-eyed (sepia) Drosophila melanogaster was studied under light conditions. Mating success was directly observed in mating vials and techniques usually applied in the studies of sexual selection ("female choice" and "multiple choice"). The comparison of sexual activity of mutant and wild types clearly indicates that they are not equally successful in matings. Sepia eye colour mutation decreases sexual activity of Drosophila melanogaster males, influences the preference ability of females and decreases the number of progeny from homogamic mating of the se x se type, as well as from heterogamic copulations in which sepia females take part. Non-random mating of wild type males and sepia females (in "multiple-choice" situation), with genetically and phenotypically different individuals, could be another mechanism for conservation of genetic polymorphism in natural populations. 相似文献
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5.
The Drosophila photoreceptor potential is thought to be composed of discrete unit potentials called bumps. The steady-state receptor potential and the accompanying voltage fluctuations were recorded intracellularly under steady illumination. The occurrence rate, effective amplitude, and duration of the bumps were deduced by assuming a shot noise model. Over a wide range of light intensity, the duration of bumps remained essentially constant (25-30 ms). Below the saturation intensity for the receptor potential, the bump rate was roughly proportional to the intensity, and the adjustment of bumps to smaller size at higher intensity was mainly responsible for the nonlinear behavior of the receptor potential. The reduction in size of bumps at increasing light intensity was found to be due mainly to the diminishing magnitude of the bump current, and not to some other secondary effects. The bump rate saturated at about 3 x 105-106 events/s. 相似文献
6.
Marika F. Walter Linda L. Zeineh Bruce C. Black Wilson E. McIvor Theodore R.F. Wright Harald Biessmann 《Archives of insect biochemistry and physiology》1996,31(2):219-233
The major pathway leading to adult cuticle melanization in Drosophila melanogaster has been investigated by a combination of biochemical and genetic approaches. By comparing catecholamine pools in newly emerged flies and in frass (excreta) collected 1 to 4 days after eclosion from wild type with those obtained from several pigmentation mutants, the major flow of catecholamines through the pathway to an unidentified final catabolite was determined. We also demonstrate that incubation with dopamine in vitro induces premature melanization in wild type unpigmented pharate adults several hours before the developmentally programmed onset of melanization, supporting the hypothesis that the availability of catecholamines may be the limiting factor determining the onset of melanization and that the major enzymatic activities that act downstream of dopa decarboxylase in the pathway are deposited into the cuticle before pigmentation begins. In vitro melanization studies with various pigmentation mutants that are associated with critical enzymatic steps in Drosophila catecholamine metabolism are consistent with their proposed function and suggest a central role of N-β-alanyldopamine in adult cuticle pigmentation. © 1996 Wiley-Liss, Inc. 相似文献
7.
Matsumoto A Matsumoto N Harui Y Sakamoto M Tomioka K 《Journal of insect physiology》1998,44(7-8):587-596
In the wild type (Canton-S) and period mutant flies of Drosophila melanogaster, we examined the effects of light and temperature on the circadian locomotor rhythm. Under light dark cycles, the wild type and per(S) flies were diurnal at 25 degrees C. However, at 30 degrees C, the daytime activity commonly decreased to form a rather nocturnal pattern, and ultradian rhythms of a 2 approximately 4h period were observed more frequently than at 25 degrees C. The change in activity pattern was more clearly observed in per(0) flies, suggesting that these temperature dependent changes in activity pattern are mainly attributable to the system other than the circadian clock. In a 12h 30 degrees C:12h 25 degrees C temperature cycle (HTLT12:12), per(0) flies were active during the thermophase in constant darkness (DD) but during the cryophase in constant light (LL). The results of experiments with per(0);eya flies suggest that the compound eye is the main source of the photic information for this reversal. Wild type and per(0) flies were synchronized to HTLT12:12 both under LL and DD, while per(S) and per(L) flies were synchronized only in LL. This suggests that the circadian clock is entrainable to the temperature cycle, but the entrainability is reduced in the per(S) and per(L) flies to this particular thermoperiod length, and that temperature cycle forces the clock to move in LL, where the rhythm is believed to be stopped at constant temperature. 相似文献
8.
Initial observations of low fertility, reduced sexual activity of males, and a high frequency of abnormalities in sperm differentiation of the wild type strain (Sevelen, Zürich) of Drosophila melanogaster, normally used in this laboratory, have lead to a study of this phenomenon and its causes. The abnormalities occur during all spermiogenetic stages and are not unique but are found with much lower frequency in normally fertile flies (Oregon R). Growth of Sevelen flies at high but sublethal temperatures (30°C) results in complete sterility, highly abnormal sperm differentiation, and a failure to recover fertility after return to normal temperatures (25° C) in the time period in which normal flies recover. — The principal factor, or factors, controlling normal sperm differentiation are located on the Y chromosome, but are thus far not precisely localized. Expression of the phenotype is modified by genetic background in which the Y chromosome is found. 相似文献
9.
Pteridines in the claret mutants of Drosophila melanogaster 总被引:2,自引:0,他引:2
10.
Mutants affected in their pigment content and in the structure of their phycobilosomes (PBS) were isolated in the cyanobacterium Synechocystis PCC 6803 by enriching a population with the inhibitor p-hydroxymercuribenzoate. Three of these mutants, PMB 2, PMB 10 and PMB 11, with original phenotypes, are described. Applying several criteria of analysis (77K absorption and fluorescence, protein electrophoretic patterns, electron microscopy), it was possible to assign the component polypeptides to each substructure of the phycobilisome. The model structure obtained fits with those described in other species PMB 10 and PMB 11, completely lacking PC, are the first source of pure PBS cores available, in which no contamination by residual PC can be feared, and are thus particularly interesting for further biochemical studies. The capacity of genetic transformation of Synechocystis PCC 6803 by chromosomal DNA makes this system very convenient for the analysis of the regulation of synthesis of the PBS constituents.Abbreviations PSI, PSII
photosystems I, II
- PBS
phycobilisomes
- PC
phycocyanin
- APC
allophycocyanin
- APC-B
alophycocyanin B
- PE
phycoerythrin
- PEC
phycoerythrocyanin
- WT
wind type
- Chl
chlorophyll
Present address: Service de Physiologie Microbienne Institut Pasteur, 28, rue du Docteur Roux, F-75724 Paris Cedex 15, France 相似文献
11.
The sensitivity of Drosophila melanogaster to ultraviolet light has been studied in wild type and recombination-deficient strains. Survival was measured as the proportion of irradiated embryos or larvae which developed to adult flies. In view of the fact that males of this species do not participate in meiotic recombination, emphasis was placed on the relative sensitivity of males and females. The results show that young wild type male larvae are more sensitive to UV radiation than are young female larvae. This difference in sensitivity, however, is not apparent in some recombination-deficient strains. In addition, young embryos of the recombination-deficient strain Df(3)sbd105/T(2;E)Xa are exceptionally sensitive to UV radiation. 相似文献
12.
Dr. Emiko Matsumoto Kazushige Hirosawa Kiyoshi Takagawa Yoshiki Hotta 《Cell and tissue research》1988,252(2):293-300
Summary A Drosophila visual mutant rdgA has photoreceptive cells which degenerate gradually after eclosion. Fine structure of the retinular cells of rdgA
KS60
and rdgA
K014
was studied during early stages of degeneration to determine the initial morphological defects. The retinular cells of these two alleles showed the following structural abnormality within 1 day after eclosion: (1) rhabdomeres were small and irregular in shape; (2) cisternae of the rough endoplasmic reticulum were more numerous than those in normal retinular cells; (3) submicrovillar cisternae were absent; and (4) lysosomes were fewer than normal. Three-dimensional reconstruction of serial sections of the ommatidia showed that the degeneration of mutant rhabdomeres proceeds more rapidly in regions remote from the nuclei. These results suggest that the process of turnover of rhabdomeric microvilli is abnormal in rdgA. We also confirmed an increase of lysosomes and destruction of cellular organelles, as reported by previous investigators at more advanced stages of degeneration. 相似文献
13.
The AP-3 adaptor protein complex has been implicated in the biogenesis of lysosome-related organelles, such as pigment granules/melanosomes,
and synaptic vesicles. Here we compare the relative importance of AP-3 in the biogenesis of these organelles in Drosophila melanogaster. We report that the Drosophila pigmentation mutants orange and ruby carry genetic lesions in the σ3 and β3-adaptin subunits of the AP-3 complex, respectively. Electron microscopy reveals dramatic
reductions in the numbers of electron-dense pigment granules in the eyes of these AP-3 mutants. Mutant flies also display
greatly reduced levels of pigments housed in these granules. In contrast, electron microscopy of retinula cells reveals numerous
synaptic vesicles in both AP-3 mutant and wild-type flies, while behavioral assays show apparently normal locomotor ability
of AP-3 mutant larvae. Together, these results demonstrate that Drosophila AP-3 is critical for the biogenesis of pigment
granules, but is apparently not essential for formation of a major population of synaptic vesicles in vivo.
Received: 1 February 2000 / Accepted: 10 April 2000 相似文献
14.
Summary The status of de novo pyrimidine synthesis in the dp mutant of Drosophila melanogaster was examined by measuring the activity of the rate-limiting orotate phosphribosyl transferase (OPRT) enzyme. Activity is significantly elevated in late third instar larvae of 5 different dp mutant strains. A more detailed analysis of a dp
ovc allele has shown that this elevation arises at about mid-larval life and persists until pupation.A low nucleotide diet causes a depression in OPRT activity in dp
ovc larvae which can be reversed by dietary supplementation of uracil. However, neither the low nucleotide diet nor uracil supplementation results in a change in the expressivity of the dp mutant phenotypes.Changes in expressivity are produced by 6-azauracil and by elevated temperature although, in those cases, the effect on OPRT activity is minimal.The significance of the observations is discussed in relation to the role of pyrimidine biosynthesis in dp expressivity and chitin synthesis. 相似文献
15.
The fine structure of developing bristles in wild type and mutant Drosophila melanogaster 总被引:10,自引:0,他引:10
J Overton 《Journal of morphology》1967,122(4):367-379
In an attempt to understand the factors involved in morphogenesis of a complex cell like a scale or bristle, the fine structure of the normal development of bristle cells in Drosophila melanogaster (Oregon R) has been studied and compared with that of the mutants sn3 and Sb. In the development of the normal bristle rounded bundles of longitudinally oriented fibrils lie just beneath the cell surface at regularly spaced intervals. Fiber bundles constitute about 20% of the cross sectional area. The cytoplasmic surface between these bundles is active in enveloping the nerve fiber associated with the bristle and in sending out cytoplasmic processes associated with which the longitudinally oriented bristle ridges form. Singed bristles are bent and twisted and the fiber bundles are present as flattened bands constituting only about 5% of the cross-sectional area. In Sb mutants the total cross-sectional area of fiber bundle material is the same as that in Oregon R, but fiber bundles are smaller and more numerous, being distributed over the larger surface of this thicker and shorter bristle. They constitute only 7% of the cross-sectional area of the bristle. In Sn3Sb mutants characteristics of each gene are exaggerated and an extremely short, wide, and irregular bristle is formed. 相似文献
16.
M A Batzer T D Desselle M D Brennan W R Lee B Tedeschi 《Biochemical and biophysical research communications》1988,150(2):655-664
The protein expressed by the alcohol dehydrogenase locus (Adh) in D. melanogaster comprises a small group of electromorphs. We are able to study the expression of these electromorphs by electrophoretic separation and subsequent probing of blots of the separated polypeptides with antiserum for alcohol dehydrogenase (ADH). In the present study we have utilized this technique to study and compare the ADH electromorphs in wild type D. melanogaster with D. melanogaster transformants which carry an Adh gene from D. grimshawi, D. hawaiiensis or D. affinidisjuncta and produced functional ADH (10, 19). We have determined that polypeptides are produced by the donor loci in the transformed flies and further show that although the molecular weight of the expressed polypeptides is similar to D. melanogaster electromorphs, the isoelectric points are not similar. Thus this methodology offers the potential to study naturally occurring ADH electromorphs and null alleles independent of enzymatic activity assays. 相似文献
17.
Neurodegenerative human diseases are caused by nerve cell death and anatomical changes in some brain regions. Molecular genetic studies of Drosophila showed that this organism can serve as a valuable test-system for conserved mechanisms underlying human nervous system disorders. Analysis of brain functions is possible when the mutants with disturbed functions are available. In this study, we have developed a unique collection of Drosophila melanogaster mutants with morphological and neurodegenerative changes in brain structure, which were induced by chemical mutagens. 相似文献
18.
Summary Amounts of chromosomal DNA were estimated for Feulgen-stained, ovarian cells from flies carrying certain mutant alleles of the otu (ovarian tumor) gene. Epithelial sheath cells and lumen cells were found to contain the diploid (2C) amount of DNA and therefore served as internal, cytophotometric standards. Mitotically active follicle cells over young tumors-from homozygous otu
1 females contained either the 2C or 4C amounts of DNA; whereas, the tumor cell population contained 2C, 4C and 8C nuclei and many intermediate values. Egg chambers also occur in homozygous otu
7 females. Follicle cells above these oocytes undergo a maximum of four cycles of endomitotic DNA replication. The accompanying nurse cells (PNC) contain polytene chromosomes. These undergo a maximum of 12 endonuclear replication cycles. The PNCs show the expected levels of DNA for the first 6 cycles and the fraction failing to replicate during subsequent cycles may be as small as 10%. Lower than expected levels of DNA were detected in PNCs from an otu
1/otu
3 ovary, reflecting roughly 20% underreplication. The latter PNCs may have been interrupted before DNA synthesis was concluded. No simple model of genomic underreplication accounts for the several different patterns of DNA behavior observed for various otu mutants. 相似文献
19.
Summary Mutants of Drosophila melanogaster which are defective in DNA synthesis have been identified among mutagen-sensitive stocks through analysis of both organ and cell cultures. A new procedure employing larval brain ganglia allows poorly fertile or sterile mutants to be analyzed for the first time. Parallel studies were performed in both tissues to establish the sensitivity of the new assay relative to that of the proven cell-culture assay. Damage was induced in the DNA of cultured cells with UV irradiation and in that of ganglial cells with the carcinogen N-acetoxy-2-acetylaminofluorene. Cultures were then pulse-labeled with 3H-thymidine, incubated in the absence of thymidine, and the newly synthesized DNA was analyzed by alkaline sucrose gradient centrifugation. The molecular weight of labeled DNA from mutant cells was compared with that from control cells to assess the effect of the mutant on DNA synthesis. Among 16 mutant stocks that were scanned in either or both tissues, seven show reductions in DNA synthesis using an undamaged template. Mutants at five different genetic loci [mus(2)205, mus(3)304, mus(3)308, mus(3)310 and mus(3)311] possess a reduced capacity to synthesize DNA on a UV-damaged template in primary cell cultures. Four of these five defects can also be detected in carcinogen-treated organ cultures. Two additional defects in postreplication repair were observed with the brainganglia assay in strains that cannot be assayed in cell culture [mus(1)108, mus(2)206].Abbreviations MMS
methyl methanesulfonate
- HN2
nitrogen mustard
- AAF
2-acetylaminofluorene
- AAAF
N-acetoxy-2-acetylaminofluorene
- DMSO
dimethyl sulfoxide 相似文献
20.
Cytophotometric studies on cells from the ovaries of otu mutants of Drosophila melanogaster 总被引:1,自引:0,他引:1
Amounts of chromosomal DNA were estimated for Feulgen-stained, ovarian cells from flies carrying certain mutant alleles of the otu (ovarian tumor) gene. Epithelial sheath cells and lumen cells were found to contain the diploid (2C) amount of DNA and therefore served as internal, cytophotometric standards. Mitotically active follicle cells over young tumors from homozygous otu1 females contained either the 2C or 4C amounts of DNA; whereas, the tumor cell population contained 2C, 4C and 8C nuclei and many intermediate values. Egg chambers also occur in homozygous otu7 females. Follicle cells above these oocytes undergo a maximum of four cycles of endomitotic DNA replication. The accompanying nurse cells (PNC) contain polytene chromosomes. These undergo a maximum of 12 endonuclear replication cycles. The PNCs show the expected levels of DNA for the first 6 cycles and the fraction failing to replicate during subsequent cycles may be as small as 10%. Lower than expected levels of DNA were detected in PNCs from an otu1/otu3 ovary, reflecting roughly 20% underreplication. The latter PNCs may have been interrupted before DNA synthesis was concluded. No simple model of genomic underreplication accounts for the several different patterns of DNA behavior observed for various otu mutants. 相似文献