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  • Articles  (2,135)
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  • Drosophila melanogaster
  • Springer  (2,135)
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  • 1
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    Springer
    Entomologia experimentalis et applicata 92 (1999), S. 289-294 
    ISSN: 1570-7458
    Keywords: parasitoid size ; Asobara ; host sex ; sex allocation ; Drosophila melanogaster ; parasitic castration
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Parasitoid females are known to preferentially allocate female eggs to hosts with the higher resource value, usually leading to oviposition of female eggs in larger hosts and male eggs in smaller hosts. For koinobiont parasitoids, if male and female hosts are of equal size at time of oviposition, but differ in size in later developmental stages, the sex of the host could be used to indicate future resource value. Using parasitoids of the braconid genus Asobara, which are larval parasitoids of Drosophila, it is shown that parasitoids emerging from female hosts are larger than those from male hosts. Given this difference in resource value, ovipositing females should preferentially allocate female eggs to female hosts. An alternative strategy would be to decrease the difference in resource value between male and female hosts by castrating male hosts. The primary sex ratio of A. tabida in their two main host species does not differ between male and female hosts. In contrast to A. tabida, A. citri is known to partially castrate male hosts, but this does not decrease the size difference between male and female hosts. As in A. tabida, there is no difference in sex allocation to male and female hosts in A. citri. Despite the clear difference between the resource value of male and female hosts, these parasitoid species do not seem to make optimal use of this difference. They may not be able to discriminate between host sexes or, alternatively, there is a presently unknown fitness disadvantage to ovipositing in female hosts.
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  • 2
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    Entomologia experimentalis et applicata 72 (1994), S. 109-114 
    ISSN: 1570-7458
    Keywords: Asobara rufescens ; parasitoid ; geogrphical variation ; microhabitat choice ; genetical isolation ; Drosophila melanogaster
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract In the Netherlands,Asobara rufescens (Föster) (Hymenoptera: Braconidae) is a parasitoid of drosophilid larvae in decaying plant material. In several places in the Mediterranean, parasitoids looking very similar toA. rufescens were collected on fermenting substrates. A hybridization experiment showed that the parasitoids were indeedA. rufescens. In an olfactometer PortugueseA. rufescens do not have a preference for either the odour of yeast or decaying leaves, while their Dutch conspecifics prefer the odour of decaying leaves. The survival probability of PortugueseA. rufescens inDrosophila melanogaster Meigen (Diptera: Drosophilidae), a species typical for fermenting substrates, is much higher than the survival probability of DutchA. rufescens in this host species. It is hypothesized that decaying plant material may be unsuitable for drosophilid larvae during part of the year in the Mediterranean, forcingA. rufescens there to broaden its microhabitat choice. The use of fermenting substrates bringsA. rufescens in contact with its siblingA. tabida Nees, a species typical for fermenting substrates in most of Europe. PortugueseA. rufescens appear to be genetically isolated fromA. tabida. In the Netherlands, where the two species occupy different microhabitats, there is only a premating barrier.
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  • 3
    ISSN: 1572-8889
    Keywords: Drosophila melanogaster ; larvae ; vision ; mutants
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Foraging-stage third-instar larvae from most wild-type (normal) Drosophila melanogaster stocks are generally repelled by light. To identify factors that affect the larval photoresponse, we elucidated the effects of age, temperature, and time on the photoresponse of larvae from a wild-type Canton-S stock. In addition, we analyzed the larvae from the LI2 isofemale line, which are unresponsive to light in a photoassay. To determine whether LI2 larvae behave abnormally on other behavioral paradigms, in comparison to Canton-S controls, we tested larvae in taste and olfactory assays and observed them to determine whether they dispersed in a food source. Like Canton-S larvae, LI2 larvae and other isofemale lines whose progenitors were collected from the same natural population are responsive to taste and olfactory stimuli. Moreover, LI2 larvae disperse in the food source, as do Canton-S larvae tested in the dark. Larvae expressing parasbl mutations, which respond normally to light but not to chemical stimuli, do not disperse normally in the food source, suggesting that dispersal may be mediated by perception of chemical cues.
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  • 4
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    Journal of insect behavior 5 (1992), S. 571-581 
    ISSN: 1572-8889
    Keywords: insect behavior ; Drosophila melanogaster ; oviposition choice ; gregarious distribution
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The oviposition behavior of single females of Drosophila melanogasterwas studied in population cages over 24 h. Each female shows a different behavior, but they can be arbitrarily separated into those which concentrate their egg laying in only one tube and those which spread it over more than two tubes. A comparison is made between females extracted from the Valdivian population and flies from lines selected for high and low aggregation. When “one-tube” females were grouped and compared with “more-than-one-tube” females, the aggregation indices between these groups were significantly different.
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  • 5
    ISSN: 1572-8889
    Keywords: Drosophila melanogaster ; locomotor activity ; new method ; quantification ; food deprivation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A new method to quantify locomotor behavior in Drosophila is presented, and compared with previous methods. It is based upon a radar wave, reflected by moving flies. A problem associated with the new apparatus is that its output is dependent on fly size. However, for the case the weight of the experimental flies has been determined, a correction is proposed. The method has been used by studying the effect of starvation upon locomotion in Drosophila melanogaster. It was found that starved flies are much more active than well fed flies. The importance of this effect under several conditions is discussed.
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  • 6
    ISSN: 1572-8889
    Keywords: larval behavior ; compound autosomes ; genetic mapping ; Drosophila melanogaster
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Genetic control of the rover/sitter behavioral polymorphism in Drosophila melanogasterlarvae was localized to the left arm of chromosome 2.Ten independent left and right compound second chromosomes were generated in isogenic rover and sitter strains by gamma irradiation and substituted into 25 different lines. Comparisons were made between lines to determine the chromosome arm contributions to rover/sitter phenotype expression.
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  • 7
    ISSN: 1572-8889
    Keywords: Drosophila melanogaster ; larval foraging behavior ; genetics ; development ; plasticity ; patch quality
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The genetically based rover/sitter behavioral difference in Drosophila melanogasterlarval foraging is expressed throughout most of the larval instars when larvae forage on food patches of differing food quality. The amount of locomotor behavior decreases when third-instar larvae of both rover and sitter strains are starved just prior to the behavioral test. Such strain differences in locomotor behavior are maintained despite the starvation-induced decrease in locomotion found in both strains. Measurements of larval body length and width, taken at 24, 48, 72, and 96 h posthatching, reveal that rover and sitter larval growth rates do not differ. The finding that rover/sitter differences are expressed in a variety of environments and throughout the majority of the larval instars should aid in attempts to uncover selection pressures which may differentially affect the two morphs in environmentally heterogeneous natural populations.
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  • 8
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    Journal of insect behavior 2 (1989), S. 575-588 
    ISSN: 1572-8889
    Keywords: aging ; behavior ; central nervous system ; Drosophila melanogaster ; Diptera
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract We have monitored the ontogeny of several behaviors performed by young Drosophila melanogasteradults. Very young flies are less active than older flies and are less responsive to gravity, light, an odorant, and sucrose applied to their tarsi. In addition, very young males do not consume sucrose or perform any courtship behaviors in response to virgin females, which provide chemical and visual stimuli to courting males. The rate at which flies become maximally competent to respond to stimuli is a function of the behavior. Sensory and motor deficits are not solely responsible for young flies' inability to respond to the stimuli, which suggests that the central nervous system continues to develop after eclosion.
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  • 9
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    Journal of insect behavior 2 (1989), S. 829-834 
    ISSN: 1572-8889
    Keywords: Drosophila melanogaster ; larval behavior ; microhabitat ; heritability
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
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  • 10
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    Journal of insect behavior 3 (1990), S. 1-12 
    ISSN: 1572-8889
    Keywords: Drosophila melanogaster ; territoriality ; age ; aggressive behavior ; experience
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Drosophila melanogastermales initiated aggressive behavior toward other males and defended territories several hours after they were able to court and mate females. Males that were 3 days or more posteclosion were more successful at holding territories than younger males. Three-day-old males established territories more readily and escalated more often against territory residents than males that were 1 day old. Residents did not usually force young males from territories until they were a few hours posteclosion. The development of territorial behavior was not affected by familiarity or prior exposure to females. Males held in isolation established territories more quickly and behaved more aggressively than males held in groups. Males that previously held territories were more likely to reestablish them after a disturbance.
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  • 11
    ISSN: 1572-8889
    Keywords: Drosophila melanogaster ; searching behavior ; foraging ; genetics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Drosophila melanogasteradults were employed in single resource patches of varying density and size and in a multiple-patch array to determine the degree to which resource dispersion influences searching success. Individuals from rover and sitter selected lines, with extreme genotypes for local search duration, are not as successful as control-line (wild-type) flies in locating sucrose drops in single patches varying in size and density. The number of new drops located differed significantly between fly lines in all patch types, except in a high-density patch, and within each fly line over the different patch sizes and densities. The similarities in number of drops found by rovers and sitters in all patch types are not reflected in the time periods spent searching. In the multiple-patch array sitters never left the central patch, whereas most rovers and con-trol-line flies found additional patches. The proximate explanations for the success or failure of the three fly lines in different patch sizes and densities relate to the looping locomotor pattern characterizing local search in D. melanogaster.The reactivation of searching each time a drop is ingested or revisited keeps an individual in the immediate vicinity of the last encountered resource. Flies from the selected lines, each exhibiting extreme types of locomotor patterns, leave patches relatively unexploited because local search consists either of rapid, nearly linear movement away from a drop in rovers or of relatively long bouts of local search in sitters, which promotes revisiting rather than locating new drops. Control-line flies locate more drops than either rovers or sitters and in less time than sitters, suggesting that their intermediate phenotype for search behavior allows for more flexibility in searching in various patch sizes and resource densities. The results are discussed with reference to environmental and physiological factors that may modify searching behavior and, possibly, enhance the survival of individuals with extreme genotypes.
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  • 12
    ISSN: 1572-8889
    Keywords: Drosophila melanogaster ; Drosophila willistoni ; sexual behavior ; species isolation ; P elements
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Molecular analysis suggests that the pomace fly Drosophila melanogaster acquired the P family of transposable elements from another Drosophila species, D. willistoni. Since the two species are distantly related, it has been assumed that transmission of P element DNA from D. willistoni to D. melanogaster was mediated by a vector. The possibility of an alternative mode of transmission was assessed by characterizing the sexual behaviors of D. willistoni males and females, then observing D. willistoni and D. melanogaster males and females to see whether males from one species interacted sexually with females from the other species in a laboratory setting. We observed that D. melanogaster males court D. willistoni females vigorously and, in some cases, stimulate the females to be receptive to copulation. However, D. willistoni males perform relatively little courtship in response to D. melanogaster females and do not attempt to copulate. Thus, it is unlikely that sexual interactions effected the transmission of P element DNA from D. willistoni to D. melanogaster in the flies' natural habitat.
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  • 13
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    Journal of insect behavior 11 (1998), S. 47-57 
    ISSN: 1572-8889
    Keywords: Drosophila melanogaster ; D. hydei ; pupation height ; pH ; acidity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract This paper describes the effects of the pH of the larval resource on the pupation height of two cosmopolitan species of Drosophila: D. melanogaster and D. hydei. The pH levels of “artificial media” were modified using solutions of acids (hydrochloric, acetic, and citric) and a positive relationship was found between pupation height and resource pH; i. e., the more acidic the resource, the closer the larvae pupated to the resource surface. The clearest trends were between pupation height and the final pH of the resource, the larvae apparently responding to the pH they encountered just before pupation commenced. When using natural resources a difference in pupation height was found between the types of fruits used but there was no obvious trend linking pupation height with pH. This suggests that some other environmental factor(s) was (were) overriding the effects of pH, and consequently resource pH may play only a minor role in determining pupation behavior in nature.
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  • 14
    ISSN: 1572-8889
    Keywords: Drosophila melanogaster ; sensillum mutant ; behavioral genetics ; olfactory stimulation ; locomotor behavior ; electroantennogram recording
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Two alleles of the mutant lozengeof Drosophila melanogaster, lzand lz3,lack basiconic sensilla on the antennal funiculus. To elucidate the role of these sensilla for the perception of food odors, we studied the locomotor behavior and the electroantennogram (EAG) activity of lozenge flies in response to olfactory stimuli. The significance of basiconic sensilla on the maxillary palps was assessed by testing the locomotion of flies surgically deprived of their palps. The behavioral data suggest that antennal and maxillary basiconic sensilla may be important receptors for short chain alcohols and organic acids but less crucial receptors for acetates, aldehydes, and ketones. In agreement with this interpretation, EAG responses to alcohols (but not to esters) were found to be markedly lower in lozengethan in the wild type.
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  • 15
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    Journal of insect behavior 5 (1992), S. 161-175 
    ISSN: 1572-8889
    Keywords: rover/sitter ; larval behavior ; genetics ; Drosophila melanogaster ; parasitoid success ; field population
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Two strains of Drosophila melanogaster, “rover” and “sitter,” differing in locomotion while foraging were simultaneously exposed to females of either Leptopilina boulardi or Ganaspis xanthopoda (parasitic Hymenoptera). These two parasitoids show different modes of host-searching behavior, ovipositor searching, or vibrotaxis, respectively. L. boulardi parasitized the sitter host strain significantly more than the rover. In contrast, G. xanthopoda parasitized the rover strain more than the sitter. In one case, L. boulardi selected far more sitters than rovers in population cage experiments. We also describe the frequencies of rovers and sitters in three natural populations where the local parasitoid community may have partially contributed to the differences in rover and sitter frequencies.
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  • 16
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    Journal of insect behavior 8 (1995), S. 835-845 
    ISSN: 1572-8889
    Keywords: aging ; Drosophila melanogaster ; phototaxis ; locomotor activity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Phototaxis was measured in young, middle-aged, and oldDrosophila melanogaster flies of both sexes. The apparatus allowed us to measure the tendency to go toward light, independently of the time needed to do so; under such conditions, phototaxis is dissociated from locomotor activity. The percentage of photopositive flies decreased slightly with age (93.96, 80.17, and 78.97%, respectively, in young, middle-aged, and old flies). Results are discussed in connection with previous data for which the tendency to go toward light and the time to do so were not dissociated.
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  • 17
    ISSN: 1572-8889
    Keywords: polymorphism ; foraging behavior ; encapsulation ability ; Drosophila melanogaster
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Larvae ofDrosophila melanogaster are polymorphic with respect to their foraging behavior. “Rovers” move around, while “sitters” stay more in one place. This difference in movements while foraging may result in differences in the rate at which these larvae are attacked by hymenopteran parasitoids, especially by those that locate their hosts by reacting to the vibrations they make. From previous work it is known thatD. melanogaster larvae show intra- and interpopulation variation in their ability to destroy parasitoid eggs by encapsulation. If rovers have a higher probability to be attacked by a parasitoid, they may have a higher developed encapsulation system as compensation for this higher attack probability. Experiments show that rovers are indeed more often attacked byAsobara tabida, a vibrotactic (=reacting to vibrations) parasitoid, than sitters. However, foraging behavior and encapsulation ability appear to be independent of each other inD. melanogaster. This shows that the large variation between populations in encapsulation ability is not a reflection of the relative proportion of rovers and sitters in the populations. It also shows that parasitoids can be an important factor in the maintenance of the foraging behavior polymorphism, because a higher encapsulation ability is not a compensation for a higher attack probability.
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  • 18
    ISSN: 1572-8773
    Keywords: Drosophila melanogaster ; evaluation ; neurotoxicity ; heavy metals
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract Heavy metals cause irreversible neurobehavioral damage in many developing mammals, but the mechanisms of this damage are unknown. The influence of three heavy metal compounds, triethyllead chloride, lead acetate and cadmium chloride, on lethality, development, behavior and learning was studied using the fruit fly,Drosophila melanogaster. This animal was used because it allows hundreds of subjects to be assayed very easily in individual experiments and because it is a system in which toxicological questions might be answered by using the techniques of modern molecular genetics. When triethyllead chloride, lead acetate or cadmium chloride was placed in the medium, the larval LC50 (± standard error) was found to be 0.090±0.004, 6.60±0.64 and 0.42±0.04mm, respectively. Each of the tested compounds produced a dose-related delay in development. In particular, they caused a delay in the development of larvae to pupae. When larvae were reared on medium containing triethyllead chloride (0.06mm), lead acetate (3.07mm) or cadmium chloride (0.11mm), phototaxis, locomotion and learning were not inhibited. Since significant neurobehavioral effects were not observed under the experimental conditions used,Drosophila does not appear to be an appropriate animal for the genetic dissection of such effects of heavy metals during development.
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  • 19
    ISSN: 1572-8889
    Keywords: Drosophila melanogaster ; mating speed ; locomotor activity ; sexual activity ; courtship sequences
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The objective of this study was to compare measures of general activity and sexual behavior for various genotypes within a strain of Drosophila melanogaster, which had known differences in mating speed. Three inbred lines of D. melanogaster differed significantly in mating speed when tested in female-choice and in single-pair experiments. Analyses of locomotor activity and sexual activity of females and males revealed no significant differences between the inbred lines. An analysis of the interplay between female and male courtship behaviors enabled the examination of signal-response differences between the inbred lines. The inbred lines with intermediate and slow mean mating speed showed a decreased number of significant transitions between female and male behavioral responses. This decrease was more severe in the slow mating line. Further, the intermediate- and slow-mating females and males displayed courtship responses toward signals of the opposite sex that were different from those of the fastmating line. Models of the relationship between behavioral activity and mating speed in Drosophila are discussed and a different explanation for variation in mating speed among the three inbred lines is considered.
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  • 20
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    Journal of insect behavior 5 (1992), S. 375-383 
    ISSN: 1572-8889
    Keywords: mating success ; male courtship ; male size ; Drosophila melanogaster ; sexual selection
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Determinants of male courtship success in Drosophila melanogasterwere examined in groups of five males sequentially presented with five individual females. Thirty-three percent of males never mated, while approximately half of the males mated two or three times. Rapid courtship initiation was associated with male success in early matings only. Male size was important for courtship outcome, but the size distributions of mating and nonmating males and their progeny numbers indicate balancing rather than directional selection on size- dependent courtship success.
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  • 21
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    Entomologia experimentalis et applicata 59 (1991), S. 51-58 
    ISSN: 1570-7458
    Keywords: Overwintering ; Cold and freezing resistance ; Developmental duration ; Cold adaptation and evolution ; Drosophila melanogaster
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract In temperate regions low temperatures seem to be the most restrictive factor for survival of Drosophila natural populations, which depends on the capacity of one or more developmental stages to resist unfavourable winter conditions. In this study we have attempted to answer the question of how D. melanogaster overwinters under natural temperature conditions. Only adults overwintered and no diapause was observed in any developmental stage. Thus, developmental duration becomes a decisive component with respect to overwintering potential and, therefore, the preadult stages are unlikely to overwinter. Possible evolutionary steps in adaptation to cold regions are discussed.
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  • 22
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    Cellular and molecular life sciences 40 (1984), S. 1396-1397 
    ISSN: 1420-9071
    Keywords: Drosophila melanogaster ; ovicidal activity ; dehydromatricaria ester ; toxicity, enhancement by UV ; polyacetylenic compounds
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Freshly laid eggs ofDrosophila melanogaster were treated with the polyacetylenic compoundcis-dehydromatricaria ester. The toxicity of the chemical was enhanced by treatments with long-wavelength ultraviolet light, and the maximum effect was observed when the UV irradiation was performed 4–5 h after the initial contact of the eggs with the chemical.
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  • 23
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    Cellular and molecular life sciences 41 (1985), S. 1346-1347 
    ISSN: 1420-9071
    Keywords: Positional information ; temperature effects ; gradients ; campaniform sensillae ; wing veins ; Drosophila melanogaster
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The mutant hairy (h) increases the number of sensillae on theDrosophila wing. This allows us to quantify a gradient that determines the type of sense organ that forms along the third long vein. Temperature significantly shifts the positional responses to this underlying gradient.
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  • 24
    ISSN: 1420-9071
    Keywords: Drosophila melanogaster ; transposable elements ; inbred lines ; insertion pattern ; transposition rate
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract A highly inbred line ofDrosophila melanogaster, stable for the insertion pattern of the transposable elements copia and mdg1, was experimentally contaminated by flies from another line. We show that the alien genome income is clearly detectable by the changes induced in the insertion profiles of transposable elements, even twenty generations later.
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  • 25
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    Cellular and molecular life sciences 51 (1995), S. 73-76 
    ISSN: 1420-9071
    Keywords: Carcinogens ; genotoxicity testing ; Drosophila melanogaster ; somatic mutation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract To provide further background data on the wing spot somatic mutation and recombination assay, 10 selected carcinogens (acetamide, acrylamide, benzo(a)pyrene, cyclophosphamide, diethylstilbestrol, 4-nitroquinoline N-oxide, propyleneimine, safrole, thiourea, and o-toluidine) were tested in this assay. 72-h-old third-instar larvae, trans-heterozygous for 2 recessive wing cell markers:multiple wing hairs (mwh) andflare 3 (flr 3) were fed with 3 concentrations of each carcinogen during the rest of their development until pupation, and the genotoxic effects were measured as significant increases in the appearance of visible mutant hair clones on the adult wing blade. Our results show that 6 of the carcinogens tested produce significant increases in wing spot frequency, at least at one of the concentrations assayed. Benzo(a)pyrene, diethylstilbestrol, safrole and thiourea were the compounds that did not increase the incidence of mutant clones.
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  • 26
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    Cellular and molecular life sciences 41 (1985), S. 745-746 
    ISSN: 1420-9071
    Keywords: Drosophila melanogaster ; salivary gland ; larval ; DNA replication ; DDT ; chromosomes ; polytene
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The inhibitory effect of DDT on the initial stage of the DNA replication process in polytene chromosomes of larval salivary gland cells ofDrosophila melanogaster was investigated and possible mechanisms for the inhibition are discussed.
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  • 27
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    Cellular and molecular life sciences 42 (1986), S. 307-309 
    ISSN: 1420-9071
    Keywords: Ecdysteroid ; sterols ; Drosophila melanogaster ; ring gland
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Brain-ring glands fromDrosophila larvae reared on a defined diet containing campesterol (24-methyl-cholesterol) as the major sterol, secreted-in addition to ecdysone-a compound identified previously as a 24-methyl analogue, 20-deoxy-makisterone A. Using ergosterol or cholesterol as the sterol component of the diet, only ecdysone was detectable in cultures of brain-ring glands.
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  • 28
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    Cellular and molecular life sciences 41 (1985), S. 946-948 
    ISSN: 1420-9071
    Keywords: Acetaldehyde oxydation ; alcohol dehydrogenase ; aldehyde dehydrogenase ; Drosophila melanogaster ; Drosophila simulans ; ethanol catabolism ; null-mutants for alcohol dehydrogenase
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Aldehyde dehydrogenase (ALDH) activity is demonstrated in four strains ofD. melanogaster lacking active alcohol dehydrogenase (ADH-null mutants). In the four strains, ALDH activities are similar to those found in a wild strain. It is concluded that ADH-null flies are able to detoxify acetaldehyde. This finding is discussed in relation with the dual function of ADH proposed recently.
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  • 29
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    Cellular and molecular life sciences 42 (1986), S. 1048-1050 
    ISSN: 1420-9071
    Keywords: Allozyme polymorphism ; linkage disequilibrium ; wine cellar and field populations ; Drosophila melanogaster
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Over three years, theAdh and α-Gpdh loci have been studied in two cellar populations ofDrosophila melanogaster and in two field populations which were each near to one of the cellars. Analyses of gene frequencies indicate that the divergence among subpopulations is greater in theAdh locus than in the α-Gpdh locus. Selection for or againstAdh S allele acting on theIn(2L)t inversion influences of the α-Gpdh alleles. This phenomenon may contribute to explain the maintenance of theAdh and α-Gpdh polymorphism and of theIn(2L)t inversion.
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    Cellular and molecular life sciences 41 (1985), S. 1078-1079 
    ISSN: 1420-9071
    Keywords: Drosophila melanogaster ; intercalating mutagens ; crossing-over ; clastogenic activity ; recombination induction
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    Topics: Biology , Medicine
    Notes: Summary In order to evaluate the effect of several intercalating compounds on crossing-over inDrosophila melanogaster females, acridine orange, acriflavine, chloroquine, ethidium bromide and quinacrine were fed separately to larvae ofy ct f/+++ genotype. Our results show that acridine orange, acriflavine and ethidium bromide increase significantly the recombination frequency at thect-f region and support the view that, for intercalating agents, there is a relationship between clastogenic activity and female recombination induction.
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    Cellular and molecular life sciences 44 (1988), S. 618-621 
    ISSN: 1420-9071
    Keywords: Sensitive period ; phenocopy ; yellow ; survivorship ; Drosophila melanogaster
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    Topics: Biology , Medicine
    Notes: Summary Yellow phenocopies ofDrosophila melanogaster were produced by raising larvae on α-DMT contaminated media. Using a survivorship test, the sensitive period for phenocopy induction was found to occur during the third larval instar of development, with increased survivorship at 1% α-DMT compared with lower concentrations. It was also found that treatment with α-DMT significantly slowed development. These findings are related to the relevant morphological and behavioral developmental pathways and to phenocopy induction.
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  • 32
    ISSN: 1420-9071
    Keywords: Genotoxicity ; somatic cells ; spot size ; Drosophila melanogaster ; methyl methanesulfonate
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    Notes: Abstract The relationship between the induction of mutant clones and the time of mutagen treatment was studied in the somatic mutation and recombination test (SMART) in wing cells ofDrosophila melanogaster. Larvae trans-heterozygous for the recessive marker mutations multiple wing hairs (mwh) and flare (flr) were produced. Batches of these larvae were then treated with mutagen at different ages spanning all three larval instars. Methyl methanesulfonate was fed acutely for 2 h by immersing the larvae in a solution of the mutagen mixed with powdered cellulose. Wings of the surviving adult flies were mounted and scored for the presence of spots. The frequency and size of single and twin spots were recorded separately. Twin spots are produced exclusively by mitotic recombination, whereas single spots can results from various types of mutational and exchange events. There exists a clear correlation between time of induction and frequency as well as size of the single spots. In young larvae only few but very large spots are induced, whereas in older larvae the frequencies are considerably increased but the sizes are smaller. The twin spots show a different relationship. Practically no twin spots are found in very young and in very old larvae. The results demonstrate that in the wing spot test the optimal age of the larvae for mutagen treatment is 72 h.
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    Entomologia experimentalis et applicata 48 (1988), S. 61-67 
    ISSN: 1570-7458
    Keywords: cytoplasmic incompatibility ; Drosophila melanogaster ; maternal inheritance ; reproductive isolation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Description / Table of Contents: Résumé Les souches de D. melanogaster récoltées à Melbourne (37°S) et Townsville (19°S) sur la côte Est de l'Australie montrent une incompatibilité partielle lorsque les femelles Melbourne sont accouplées aux mâles Townsville. Une telle incompatibilité n'est décelée, ni dans les croisements intrapopulations, ni dans le croisement réciproque. Le taux d'éclosion des oeufs est réduit d'environ 30% dans le croisement incompatible, mais la viabilité des larves n'est pas modifiée. Les éléments, mâle et femelle, de ce système d'incompatibilité sont hérités maternellement pendant 3 générations de croisements en retour. La compatibilité peut être intégralement rétablie en cultivant pendant une génération la souche Townsville avec un régime contenant de la tétracycline, et partiellement rétablie en utilisant des mâles âgés de 2 semaines.
    Notes: Abstract Drosophila melanogaster (Meigen) females from stocks collected at Melbourne (latitude 37°S) show partial incompatibility when mated with males from stocks collected at Townsville (latitude 19°S) on the east coast of Australia. The reciprocal cross is compatible. Eggs have reduced hatchability in the incompatible cross. The incompatibility is maternally inherited over three generations. Compatibility can be restored by culturing Townsville flies on medium with tetracycline for one generation and by using 2-week-old Townsville males.
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  • 34
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    Entomologia experimentalis et applicata 52 (1989), S. 159-166 
    ISSN: 1570-7458
    Keywords: Sexual isolation ; sexual maturation ; Drosophila melanogaster ; Drosophila simulans
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    Topics: Biology
    Description / Table of Contents: Résumé Des lignées isofemelles de D. simulans ont été examinées pour déterminer l'âge de la maturité sexuelle des mâles avec des femelles conspécifiques et pour établir la fréquence de l'hybridation avec des femelles de D. melanogaster. Les mâles ont commencé à être sexuellement mûrs le premier jour après l'émergence, mais leur aptitude à la copulation a augmenté lentement pendant le jour suivant. Les estimations, tant de l'âge du début de la maturation sexuelle que de l'âge du passage de mâle immature à mâle sexuellement mûr dépendaient étroitement des génotypes des femelles utilisées dans les expériences. Il n'y avait pas de différences nettes entre les lignées de mâles. Par contre, des différences dans les fréquences d'hybridation avec les femelles de D. melanogaster ont été observées. De ces résultats, on peut conclure que les différences dans la réussite des hybridations des lignées de mâles de D. simulans n'étaient pas dues à la vitesse de maturation sexuelle des mâles.
    Notes: Abstract Isofemale lines of D. simulans were examined to determine the age of sexual maturity of males with conspecific females, and for the frequency of hybridization with D. melanogaster females. Males started to mature sexually on the first day after eclosion but their ability to mate slowly increased during the following day. The estimates of both the age sexual maturation started and the switch from immature to mature males were strongly dependent on the female genotypes used in the tests. No clear differences in speed of maturation were apparent between male lines. In contrast, differences in frequency of hybridization with D. melanogaster females did occur. From the above results it is concluded that the differential hybridization success of male D. simulans lines is not related to the speed at which males mature sexually.
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  • 35
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    Entomologia experimentalis et applicata 42 (1986), S. 145-149 
    ISSN: 1570-7458
    Keywords: Drosophila melanogaster ; polymorphisme électrophorétique ; populations naturelles françaises ; temps ; Drosophila melanogaster ; enzymatic polymorphism ; French natural populations ; time
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    Topics: Biology
    Description / Table of Contents: Summary Temporal patterns of allozyme variation over time have been examined for five polymorphic enzyme loci in 12 french natural populations of Drosophila melanogaster. Taken in their totality, the data show only slight changes in the genetical structure of these populations between years. The good viability of the imagoe at low temperatures and the occurrence of winter immediately after the demographic burst of the species in France involve that the population sizes during winter are probably sufficient to eliminate the genetic drift. Therefore, the stability in the genetical composition from one autumn to another could be explained by the way that the populations analyzed are panmictic.
    Notes: Abstract L'évolution dans le temps du polymorphisme de 5 locus enzymatiques a été suivie pour 12 populations naturelles françaises de Drosophila melanogaster. La structure génétique de ces populations ne varie pas, ou peu, d'un automne à l'autre. La bonne résistance au froid des imagos et le fait que la période hivernale suive celle de l'explosion démographique de l'espèce en France, indiquent que les populations analysées ne doivent pas subir d'importantes réductions de leurs effectifs durant l'hiver, susceptibles d'entraîner une forte dérive génétique. Dans ces conditions, le maintien de la même structure d'une année à l'autre peut s'expliquer par le fait que les populations sont panmictiques.
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  • 36
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    Biology and fertility of soils 9 (1990), S. 101-109 
    ISSN: 1432-0789
    Keywords: Phryganella acropodia ; Testate amoeba ; Growth rate ; Rhizopoda ; Feeding ; Fungal species ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Clones of Phryganella acropodia were cultivated under different trophic conditions with bacteria as the food source. The doubling time was estimated to be 3 days. The edibility of four species of fungi, Aspergillus niger, Cunninghamella echinulata, Penicillium echinulatum and Stilbella bulbicola, was tested, but only Penicillium enchinulatum and Stilbella bulbicola were eaten and digested by the amoeba. An ultrastructure examination showed that there are two contractile vacuoles, many dictyosomes, a single nucleus with several nucleoli, and peroxisomes. The pseudopodia are filiform when attached to the substrate but change to lobose when the animal is floating. A thin organic membrane covers the aperture of resting forms.
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  • 37
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    Calcified tissue international 33 (1981), S. 603-618 
    ISSN: 1432-0827
    Keywords: Preameloblasts ; Tooth germs ; Monkey ; Enamel ; Ultrastructure
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    Topics: Biology , Medicine , Physics
    Notes: Summary Cytodifferentiation of inner enamel epithelium and the adjacent connective tissue from the tip of the cervical loop to the initiation of enamel elaboration in twoMacaca species was examined. Ten- to twelve-month-old specimens were fixed by perfusion and the permanent tooth buds were prepared for transmission electron microscopy. At the cervical loop proper, inner enamel epithelium cells have lobed nuclei, a paucity of cytoplasm, and wide extracellular spaces; the basal lamina facing the dental papilla is straight. With increasing distance from the tip of the cervical loop, the following changes occur gradually: (a) preameloblasts elongate from 15 to 45 µm, and their organelles, particularly mitochondria and profiles of rough endoplasmic reticulum, become more numerous; (b) extracellular spaces decrease between preameloblasts starting at the basal (infranuclear) end; (c) the basement membrane becomes convoluted and associated with aperiodic fibers; (d) preodontoblast projections penetrate the aperiodic fibers; (e) collagen fibers subjacent to the basement membrane increase in density, with particularly thick fibers paralleling the aperiodic fibers. These modifications occur within three-fourths of the distance from the tip of the cervical loop to the mineralization front. The condensation of preodontoblasts is followed immediately by predentin synthesis. Concomitantly, the basement membrane breaks down and the aperiodic fibers are engulfed by preameloblasts. Preameloblast projections penetrate junctional predentin, contact mineralized dentin, and enamel synthesis ensues. At this stage the ameloblast is 45 µm long, the nucleus is central or basal, the Golgi apparatus has migrated apically, but the Tomes' process has not yet formed. The results indicate that odontogenesis inMacaca monkeys more closely resembles human odontogenesis than does that in the murine rodents.
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  • 38
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    Calcified tissue international 10 (1972), S. 38-48 
    ISSN: 1432-0827
    Keywords: Bivalve ; Molluse ; Shell ; Carbonates ; Ultrastructure
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    Topics: Biology , Medicine , Physics
    Description / Table of Contents: Résumé La technique du bombardement à l'aide d'ion d'argon est utilisée pour réduire l'épaisseur de la coquille de carbonate de calcium des bivalvesMytilus etMercenaria pour examen au microscope électronique par transmission et en diffraction électronique; une comparaison est réalisée à l'aide de répliques simples, servant de témoins. Les résultats obtenus confirment les études antérieures de répliques et de microscopie par balayage. De plus, une structure “aérée” est mise en évidence dans la coquille des aragonites, et surtout dans le nacre deMytilus. Cette structure est interprêtée comme un artefact induit par la chaleur, formé par l'inclusion d'eau et de matériel organique, interprétation qui concorde avec les études chimiques et de microscopie électronique.
    Abstract: Zusammenfassung Die Beschießung mit Argonionen wurde angewendet, um die Dicke von Calciumcarbonat-Schalen der zweischaligen MuschelnMytilus undMercenaria zu reduzieren. Diese Technik erlaubte die Ausführung von Transmissions-Elektronenmikroskopie und Elektronendiffraktion, wobei gleiche Proben nach einer bereits bestehenden Methode vorbereitet und als Kontrollen herangezogen wurden. Es wurden zusätzliche Resultate zu den Muschelstruktur-studien erhalten, welche früher publizierte Arbeiten unterstützen, die mit der Abklatschmethode und der Raster-Elektronenmikroskopie ausgeführt worden waren. Zusätzlich wurde eine „schaumartige” Struktur der Muschelaragoniten, besonders im Perlmutter vonMytilus, beobachtet. Da es sich um ein durch Hitze verursachtes Artefakt handelt, wird diese Struktur als Einschlüsse von Wasser und organischem Material interpretiert, was den Befunden von verschiedenen veröffentlichten chemischen und elektronenmikroskopischen Arbeiten entspricht.
    Notes: Abstract Use is made of the argon ion-bombardment technique to reduce the thickness of calcium carbonate shells of the bivalvesMytilus andMercenaria for transmission electron microscopy and electron diffraction, with comparison of single-stage replicas of similar specimens serving as controls. As an additional approach to shell structure studies, it gives results which support earlier published work with both replicas and scanning microscopy. In addition, a “frothy” structure is detected in the shell aragonites, especially inMytilus nacre. As a heat-induced artifact, it is interpreted as representing trapped water and organic material inclusions, an interpretation consistent with several published chemical and electron microscope studies.
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  • 39
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    Calcified tissue international 10 (1972), S. 216-222 
    ISSN: 1432-0827
    Keywords: Ultrastructure ; Callus ; Osteoclast ; Endocytosis ; Lysosomes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Description / Table of Contents: Résumé La bordure en brosse des ostéoclastes de cals de fractures de rats présente des plissements complexes de la membrane cytoplasmique formant des canaux étroits. L'absorption d'un produit exogène opaque aux électrons (des macromolécules de dioxyde de thorium) s'effectue par l'intermédiaire de ces canaux, par un «courant» membranaire. Les contenus des canaux sont transférés à des lysosomes («granules spécifiques»), situés sous la bordure en brosse. Dans des «régions de transition», adjacentes à cette dernière, l'absorption de dioxyde de thorium se fait par «vésiculation membranaire» (endocytose classique).
    Abstract: Zusammenfassung Der gekrauste Rand der Osteoklasten im Frakturcallus von Ratten besteht aus komplexen Einstülpungen der Plasmamembran, die enge Kanälchen bildet. Die Absorption einer exogenen, elektronisch dichten Verbindung, Thoriumdioxyd, erfolgt durch diese Kanäle, offenbar durch einen „Membranfluß”. Der Inhalt der Kanäle wird zu den Lysosomen („spezifische Granula”) geführt, welche unter dem gekrausten Rand liegen. In „Übergangsgebieten”, welche sich neben dem gekrausten Rand befinden, scheint die Aufnahme der Thoriumdioxydpartikel durch „Bläschenbildung in der Membran” (konventionelle Endocytose) stattzufinden.
    Notes: Abstract The ruffled border of osteoclasts in the fracture callus of rat consists of complex infoldings of the plasma membrane forming narrow channels. Absorption of an exogenous, electron-dense compound, thorium dioxide, has been shown to take place via these channels, apparently through “membrane flow”. The contents of the channels are transferred to lysosomes (“specific granules”) located subjacent to the ruffled border. In “transitional regions” adjacent to the ruffled border, uptake of thorium dioxide particles appeared to occur through “membrane vesiculation” (conventional endocytosis).
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    Calcified tissue international 25 (1978), S. 145-159 
    ISSN: 1432-0827
    Keywords: Bird egg shell ; Ultrastructure ; Calcification ; Electron diffraction ; Microanalysis
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    Topics: Biology , Medicine , Physics
    Notes: Summary The egg-shell of Japanese quail was studied by several techniques. Semithin sections (1μm thick) of non-decalcified shell were observed by normal and polarized light microscopy. Thin sections of non-decalcified shell, examined by transmission electron microscopy, permitted us to observe the forms and dimensions of crystals of calcite within different layers of the shell: mammilary layer, layer of cones, palissade layer and surface crystal layer. There appears to be two distinct zones in the layer of cones as well as in the superficial crystal layer. Electron microdiffraction revealed the orientation of calcite crystals in the columns. Some crystal defects (twins?) were described and the possibility of their artefactual formation during ultramicrotomy is discussed. Localization of Ca, Mg, P and S were made by X-ray microanalysis of semithin sections. This technique shows that shell membranes, and chiefly the true cuticle, are also mineralized but, in these layers, minerals are not crystallized. Otherwise the distribution of Mg is not uniform throughout the shell thickness; it is less concentrated in the external zone of the layer of cones. These results together with observation of developing shells by scanning electron microscopy allowed us to propose a scheme for shell organization of the quail egg. This organization was related with decalcification which occurs during hatching.
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  • 41
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    Calcified tissue international 24 (1977), S. 215-222 
    ISSN: 1432-0827
    Keywords: Mineralization ; Osteodentin ; Intracellular ; Ultrastructure ; Microanalysis
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    Topics: Biology , Medicine , Physics
    Notes: Summary Newly formed osteodentin obtained from the anterior extremities of fetal or young rat incisors was observed by means of electron microscopy and electron probe X-ray microanalysis. Cells related to osteodentin formation frequently showed membrane bound intracellular bodies containing varying amounts of fine, needle-shaped crystals, which were identified as apatite. The intracellular clusters of apatite crystals were extruded from the cells through membrane fusion or cellular degeneration. These extracellular clusters seemed to be gradually incorporated into the mineralizing collagenous matrix, which developed around them. Frequent occurrence of dense, dotshaped or filamentous profiles suggested that the dense bodies seen in the perinuclear regions or in the Golgi area were the sites of crystal formation. Energy dispersive X-ray point analysis showed that the intracellular or extracellular apatite clusters contained sulfur in a concentration higher than was present in the mineralizing collagenous matrix. Furthermore, wave dispersive X-ray line analysis showed that the concentration of sulfur was higher in the osteodentin matrix than in the dentin matrix. The sulfur detected is presumed to be contained in acid mucopolysaccharides, which were distributed more heavily in the osteodentin matrix than in the dentin matrix. On the basis of these data, it was concluded that the unique chemical and structural characteristics of the osteodentin result primarily from the incorporation of apatite clusters of intracellular origin and associated acid mucopolysaccharides.
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  • 42
    ISSN: 1432-0827
    Keywords: Bone resorption ; Osteogenesis ; Fish bone ; Osteocytes ; Ultrastructure
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    Notes: Summary The comparative ultrastructure of fish bone osteogenesis and resorption induced by scale removal was described in the osteocytic (cellular-boned)Carassius auratus and the anosteocytic (acellular-boned)Tilapia macrocephala. Osteocytes, present in osteocytic bone, were lacking in anosteocytic bone. In osteocytic bone the osteoblast secreted a collagenous preosseous matrix in which it became enmeshed and then was termed a preosteocyte. When the preosseous matrix mineralized, the preosteocyte was termed an osteocyte and was completely surrounded by bone. In anosteocytic bone the osteoblasts receded from the mineralizing front and never became trapped as osteocytes. During resorption, types A and B resorptive cells, present in both bone types, invaded the matrix and demineralized the osseous zone. These cells were characterized by large amounts of granular endoplasmic reticulum and intracellular inclusions containing crystal-like material. Although functionally similar to mammalian osteoclasts, these cells lacked a characteristic ruffled border and were not multinucleated. The osteocytes of cellular bone did not appear to be involved during demineralization.
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    Calcified tissue international 4 (1969), S. 84-90 
    ISSN: 1432-0827
    Keywords: Ultrastructure ; Inorganic salts ; Atherosclerosis ; Diffraction ; Aorta
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    Topics: Biology , Medicine , Physics
    Description / Table of Contents: Résumé La diffraction à rayons X, la diffraction électrique et le microscope électronique suggérent qu'en dehors des composants usuels de calcium phosphate (apatite), un nombre d'autres éléments et radicaux sont également présents dans l'arteriosclérose aortique, lesquels sont capables de jouer un rôle dans le développement de la plaque «calcifiée» et dans celui de la lésion anorganique, caractéristique pour l'artériosclerose juvenile. Selon les cas étudies, l'artériosclerose aortique peut se présenter déjà au cours de la troisième decade de la vie et sa composition anorganique est presq'identique à celle de la plaque développée.
    Abstract: Zusammenfassung Sowohl die Befunde der Röntgendiffraktion als auch jene der Elektronendiffraktion und der Elektronenmikroskopie lassen vermuten, daß bei der Aortenatherosklerose zusätzlich zu den üblichen Komponenten von Calciumphosphat (Apatit) eine Reihe anderer Elemente und Radikale vorhanden sind; diese können eine Rolle spielen bei der Entwicklung der “verkalkten” Plaque und bei anorganischen Läsionen juveniler Atherosklerosen. Bei den untersuchten Fällen kann die Aortenatherosklerose bereits im 30. Lebensjahr auftreten; die anorganische Zusammensetzung der Plaque ist nahezu identisch mit jener der bereits entwickelten.
    Notes: Abstract X-ray diffraction, electron diffraction and electron microscopy suggest that in aortic atherosclerosis, in addition to the usual components of calcium phosphate (apatite), a number of other elements and radicals are present which may play a role in the development of the “calcified” plaque and in juvenile atherosclerotic inorganic lesion. In the cases studied, aortic atherosclerosis may appear as early as in the third decade and its inorganic composition is almost identical with the developed plaque.
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  • 44
    ISSN: 1432-0827
    Keywords: Periodontal ligament fibroblast ; Mineralized nodule ; Ultrastructure
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    Topics: Biology , Medicine , Physics
    Notes: Summary The purposes of this study were to determine whether periodontal ligament (PDL) cells are capable of producing mineralized nodules in vitro and to analyze ultrastructural features of the nodules. Rat PDL cells were obtained from coagulum in the socket at 2 days after tooth extraction and cultured at confluence in standard medium containing Dulbecco's Modified Eagle's Medium supplemented with 10% FBS and antibiotics. To test mineralized nodule formation, cells were further cultured for an additional 3 weeks in the standard medium containing (1) ascorbic acid (50 μg/ml) and sodium β-glycerophosphate (10 mM), (2) ascorbic acid, sodium β-glycerophosphate, and dexamethasone (5 μM), or (3) ascorbic acid alone. Cells were then fixed in 2.5% glutaraldehyde, postfixed in 1% OsO4, and prepared for light and electron microscopy. Threedimensional nodules containing mineralized matrices were formed only when the cells were cultured in the presence of ascorbic acid and dexamethasone. They were composed of multilayered fibroblasts (up to 13 layers), and highly organized collagen fibrils with 64 nm cross-banding patterns between the cell layers. The fibroblasts in the nodules exhibited an elongated shape with a high degree of cytoplasmic polarity throughout the nodule, and have the morphological features of PDL fibroblasts as seen in vivo. Mineral deposition with needle-like crystals was initiated on collagen fibrils located in intercellular spaces of the upper cell layers and became increasingly heavier towards the bottom half of the nodules. X-ray microanalysis and electron diffraction analysis confirmed that mineral deposition contained calcium and phosphate in the form of immature hydroxyapatite. These nodules contained neither osteoblasts nor osteocytes, and have their own morphological organization and characteristics which differ from those formed by bone cells in culture. Therefore, these data suggest that PDL cells are capable of forming mineralized tissue in vitro with the morphological characteristics different from bone mineralized nodules.
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    Calcified tissue international 9 (1972), S. 296-309 
    ISSN: 1432-0827
    Keywords: Osteoclasts ; Enzyme ; Parathyroid ; Microdissection ; Ultrastructure
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    Topics: Biology , Medicine , Physics
    Description / Table of Contents: Résumé Une nouvelle méthode d'isolement d'ostéoclastes est mise au point pour des analyses biochimiques et de microscopie électronique. Pour isoler les cellules par microdissection, des empreintes d'os métaphysaire sont utilisées. Cette méthode, supérieure aux coupes d'os, permet une meilleure préservation cytologique et enzymatique et permet d'obtenir des cellules totales plus faciles à manipuler, avec des résultats plus reproductibles. Par analyse planimètrique de cellules isolées, colorées histochimiquement, il apparait que les ostéoclastes constituent plus de 90% de la masse de l'échantillon. Les concentrations de la phosphatase acide et de certaines enzymes, liées au nucléotide pyridinique, entrant dans le métabolisme de l'acide citrique, sont déterminées dans des échantillons d'ostéoclastes, pesant de 0,2 à 2,0 μg, isolés à partir de rats normaux et parathyroidectomisés. L'activité en aconitase, mesurée en direction de la transformation de citrate en isocitrate, est de 0,5–0,8 M/Kd/H, la plus faible des activités étudiées. Les activités en GDH et NADP-ICDH sont 5 à 10 fois supérieures que celle de l'aconitase, mais seulement un dixième à un tiers de celle de la phosphatase acide, de la déshydrogénase lactique ou malique.
    Abstract: Zusammenfassung Es wird eine neue Technik beschrieben, welche die Isolierung von Osteoklasten für biochemische und elektronenmikroskopische Untersuchungen ermöglicht. Als Ausgangsmaterial zur Zellisolierung wurden Abstriche von Metaphysenknochen benützt. Die Verwendung von Abstrichen bietet gegenüber Knochenschnitten wichtige Vorteile, wie z.B. eine bessere Erhaltung der cytologischen und enzymatischen Eigenschaften sowie die Gewinnung von unverletzten Zellen, welche leichter verarbeitet werden können und besser reproduzierbare Daten ergeben. Durch planimetrische Analyse der histochemisch gefärbten Ausstriche von isolierten Zellen konnte nachgewiesen werden, daß die Osteoklasten über 90% des gesamten Probenmaterials ausmachen. Die Mengen verschiedener Enzyme, welche an Pyridinnukleotid gebunden und am Citronensäuremetabolismus beteiligt sind, sowie der sauren Phosphatase wurden in Osteoklastenproben bestimmt, welche ein Gewicht von 0,2–2,0 μg hatten und aus Knochen von normalen und mit Parathyroidextrakten behandelten Ratten isoliert worden waren. Die Aktivität der Aconitase, welche in der Richtung von Citrat zu Isocitrat gemessen wurde, war mit 0,5–0,8 M/Kd/H die niedrigste aller untersuchten Aktivitäten. Die Aktivitäten der GDH und der NADP-ICDH waren 5–10mal höher als jene der Aconitase, entsprachen jedoch nur einem Zehntel bis einem Drittel derjenigen der sauren Phosphatase, der Laktat- oder der Malatdehydrogenase.
    Notes: Abstract A new method is described by which osteoclasts can be isolated for biochemical and electron microscopic analyses. As a source of cells for isolation by microdissection, imprints of metaphyseal bone were used. The use of imprints provides important advantages over bone sections, including a higher degree of cytologic and enzymatic preservation, and the delivery of whole cells which are more readily manipulated and which yield data that are more readily reproduced. By planimetric analysis of the histochemically-stained isolated cell samples, it was shown that osteoclasts represent over 90% of the sample mass. The levels of several of the pyridine nucleotide-linked enzymes involved in citric acid metabolism, as well as acid phosphatase, were determined in osteoclast samples weighing 0.2 to 2.0 μg isolated from normal and parathyroid-treated rats. Aconitase activity measured in the direction of citrate to isocitrate was 0.5–0.8 M/Kd/H, the lowest of the activities studied. The activities of GDH and NADP-ICDH were 5 to 10 times higher than that of aconitase but only a tenth to a third that of acid phosphatase, lactic or malic dehydrogenase.
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  • 46
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    Calcified tissue international 7 (1971), S. 191-200 
    ISSN: 1432-0827
    Keywords: Serpulid ; Polychaete ; Hydroxyapatite ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Description / Table of Contents: Résumé Un petit groupe de cellules épithéliales de la surface antérieure du col du serpulidePomatoceros caeruleus contient des vacuoles, remplies de matériel cristallin. Les cristaux présenttent des aspects rhomboédriques ou rectangulaires. La diffraction électronique montre qu'ils sont constitués par de l'hydroxyleapatite et du phosphate de calcium et de magnésium. Les apex des cellules sont bordés de microvillosités. Certaines cellules ont des cils apicaux. Un appareil de Golgi est visible dans le cytoplasme apical. De nombreuses mitochondries sont dissé minées dans le cytoplasme. Le role éventuel de ces cellules, a contenu minéral, dans la mise en réserve de calcium et/ou de phosphore est envisagé.
    Abstract: Zusammenfassung Ein kleiner Zellverband im Epithel der vorderen Oberfläche am Hals des SerpulidsPomatoceros caeruleus enthält membrangebundene Vakuolen, welche mit kristallinem Material gefüllt sind. Die Kristalle haben rhomboide oder rechteckige Formen; mittels Elektronendiffraktion konnte nachgewiesen werden, daß sie aus Hydroxyapatit und Calciummagnesiumphosphat bestehen. Die oberen Enden der Zellen sind von Microvilli eingefaßt. Einige der Zellen haben zudem apikale Zilien. Die Zellen enthalten Golgi-Apparate im apikalen Cytoplasma. Eine große Anzahl von Mitochondrien sind über das, ganze Cytoplasma verteilt. Die mögliche Funktion dieser mineralhaltigen Zellen als Aufbewahrungsorte für Calcium und/oder Phosphor wird besprochen.
    Notes: Abstract A small patch of cells in the epithelium of the anterior surface of the collar of the serpulidPomatoceros caeruleus contains membrane-bound vacuoles filled with crystalline material. The crystals have rhomboidal or rectangular profiles and have been shown by electron diffraction analysis to be composed of hydroxyapatite and calcium magnesium phosphate. The apices of the cells are bordered by microvilli. Some cells also have apical cilia. The cells contain Golgi complexes in the apical cytoplasm. Large numbers of mitochondria are distributed thoughout the cytoplasm. The possible function of these mineral-containing cells as sites for storage of calcium and/or phosphorus is discussed.
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  • 47
    ISSN: 1432-1432
    Keywords: Esterase ; Gene cluster ; Pseudogene ; Drosophila melanogaster
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The α-esterase cluster ofD. melanogaster contains 11 esterase genes dispersed over 60 kb. Embedded in the cluster are two unrelated open reading frames that have sequence similarity with genes encoding ubiquitin-conjugating enzyme and tropomyosin. The esterase amino acid sequences show 37–66% identity with one another and all but one have all the motifs characteristic of functional members of the carboxyl/cholinesterase multigene family. The exception has several frameshift mutations and appears to be a pseudogene. Patterns of amino acid differences among cluster members in relation to generic models of carboxyl/cholinesterase protein structure are broadly similar to those among other carboxyl/cholinesterases sequenced to date. However the α-esterases differ from most other members of the family in: their lack of a signal peptide; the lack of conservation in cysteines involved in disulfide bridges; and in four indels, two of which occur in or adjacent to regions that align with proposed substrate-binding sites of other carboxyl/cholinesterases. Phylogenetic analyses clearly identify three simple gene duplication events within the cluster. The most recent event involved the pseudogene which is located in an intron of another esterase gene. However, relative rate tests suggest that the pseudogene remained functional after the duplication event and has become inactive relatively recently. The distribution of indels also suggests a deeper node in the gene phylogeny that separates six genes at the two ends of the cluster from a block of five in the middle.
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  • 48
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    Journal of molecular evolution 27 (1988), S. 142-146 
    ISSN: 1432-1432
    Keywords: Drosophila melanogaster ; Adh ; Thermostable allele ; DNA sequence
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The nucleotide sequence of theFast-Chateau Douglas isolate of the thermostable alcohol dehydrogenase allele is compared with the sequences of theSlow andFast alleles ofDrosophila melanogaster. Conceptual translation of theFChD sequence indicates that the thermostable polypeptide has the diagnostic FAST amino acid replacement at residue 192 and an additional replacement of serine for proline at residue 214. This suggests aFast origin for the thermostableAdh allele. However, some of the biochemical properties of the FCHD protein resemble those of the SLOW rather than the FAST polypeptides. The serine for proline replacement confers upon the thermostable polypeptide substrate specificities and some kinetic parameters similar to the SLOW protein. The same replacement substitution within the third coding exon also appears to alter the ADH protein concentration to a level similar to the SLOW polypeptide and the probable effect is at the level of mRNA concentration. The low level of nucleotide sequence variation, other than that leading to the amino acid substitution, suggests a recent origin for the thermostable allele. The time since divergence of theFChD sequence fromFast is estimated to be approximately 260,000–470,000 years.
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  • 49
    ISSN: 1432-1432
    Keywords: Duplications ; Complementation ; Drosophila melanogaster ; Maroon-like ; Rosy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Gene duplications must play an important role in the evolutionary development of living organisms. Presented here is a general scheme that uses complementary alleles to isolate gene duplications in diploid organisms. The technique was used inDrosophila melanogaster to assess the rate of spontaneous gene duplication at two loci, maroon-like and rosy. The results indicate (1) that the rate of duplication of the maroon-like locus is on the order of 2.7×10−6; (2) that the rate of duplication of the rosy locus is approximately 1.7×10−4; and (3) that duplication occurs in males, suggesting that there may actually be two modes of gene duplication inDrosophila melanogaster.
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  • 50
    ISSN: 1432-1432
    Keywords: Drosophila melanogaster ; Evolution ; Hybrid dysgenesis ; I elements ; Transposons
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary There are two categories of strains inDrosophila melanogaster with respect to the I-R system of hybrid dysgenesis. The inducer strains contain particular transposable elements named I factors. They are not present in the strains of the other category called reactive (R) strains. Defective I elements are present in the pericentromeric regions of both categories of strains. This last subfamily of I sequences has not yet been described in detail and little is known about its origin. In this paper, we report that the defective I elements display an average of 94% of sequence identity with each other and with the transposable I factor. The results suggest that they cannot be the progenitors of the present day I factors, but that each of these two subfamilies started to evolve independently several million years ago. Furthermore, the sequence comparison of these I elements with an active I factor fromDrosophila teissieri provides useful information about when the deleted I elements became immobilized.
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  • 51
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    Journal of molecular evolution 32 (1991), S. 415-420 
    ISSN: 1432-1432
    Keywords: Drosophila melanogaster ; Drosophila virilis ; mastermind ; Gene comparison ; Repetitive sequences ; Homopolymers ; Evolution
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Themastermind gene ofDrosophila melanogaster encodes a novel, highly repetitive nuclear protein required for neural development. To identify functionally important regions we have initiated an interspecific comparison of the gene inDrosophila virilis. Mastermind transcription and genomic organization are similar in both species and sequence analysis reveals significant conservation in a major cluster of charged amino acids. In contrast, extensive variation is noted in homopolymer domains that immediately flank the acidic cluster. Distinct patterns of evolutionary change can be identified: the major difference between unique regions are occasional amino acid substitutions whereas the repetitive areas are characterized by numerous large in-frame insertions/deletions and a nearly threefold higher rate of amino acid replacement. Conservation of the acidic domain suggests that it has an important functional role whereas the hypervariable homopolymer regions appear to be under less selective constraints than adjacent unique areas.
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  • 52
    ISSN: 1432-1432
    Keywords: Gene duplication ; Gpdh gene ; Polymorphism ; Drosophila melanogaster
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The glycerol-3-phosphate dehydrogenase (GPDH, E. C. 1.1.1.8) gene ofDrosophila melanogaster contains a tandem duplication of a 4.5-kb-long DNA fragment. Survey of theGpdh gene region by the Southern blot analysis revealed the following features of this gene duplication: (1) The duplication was not observed in chromosome lines that carryIn(2L)t, a cosmopolitan chromosomal inversion in this species. The duplication and the inversion are in linkage disequilibrium. (2) The duplication is polymorphic in the Japan and US natural populations examined. Its frequency is 0.26 on an average inIn(2L)t-free chromosomes. (3) Triplication is absent or has not become frequent in the populations surveyed. Possible evolutionary factors of this duplication polymorphism are discussed.
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  • 53
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    Journal of molecular evolution 41 (1995), S. 430-439 
    ISSN: 1432-1432
    Keywords: Cytochrome proteins ; Molecular evolution ; Drosophila melanogaster ; Drosophila virilis ; Gene structure and sequence
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Cytochrome proteins perform a broad spectrum of biological functions ranging from oxidative metabolism to electron transport and are thus essential to all organisms. The b-type cytochrome proteins bind heme noncovalently, are expressed in many different forms and are localized to various cellular compartments. We report the characterization of the cytochrome b5 (Cyt-b) gene of Drosophila virilis and compare its structure to the Cyt-b gene of Drosophila melanogaster. As in D. melanogaster, the D. virilis gene is nuclear encoded and single copy. Although the intron/exon structures of these homologues differ, the Cyt-b proteins of D. melanogaster and D. virilis are approximately 75% identical and share the same size coding regions (1,242 nucleotides) and protein products (414 amino acids). The Drosophila Cyt-b proteins show sequence similarity to other b-type cytochromes, especially in the N-terminal heme-binding domain, and may be targeted to the mitochondrial membrane. The greatest levels of similarity are observed in areas of potential importance for protein structure and function. The exon sequences of the D. virilis Cyt-b gene differ by a total of 292 base changes. However, 62% of these changes are silent. The high degree of conservation between species separated by 60 million years of evolution in both the DNA and amino acid sequences suggests this nuclear cytochrome b5 locus encodes an essential product of the Drosophila system.
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  • 54
    ISSN: 1432-1432
    Keywords: Urate oxidase ; Drosophila pseudoobscura ; Drosophila melanogaster ; Nucleotide sequence ; Evolutionary comparison ; Gene regulation ; Malpighian tubules
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The urate oxidase (UO) transcription unit of Drosophila pseudoobscura was cloned, sequenced, and compared to the UO transcription unit from Drosophila melanogaster. In both species the UO coding region is divided into two exons of approximately equal size. The deduced D. pseudoobscura and D. melanogaster UO peptides have 346 and 352 amino acid residues, respectively. The nucleotide sequences of the D. pseudoobscura and D. melanogaster UO protein-coding regions are 82.2% identical whereas the deduced amino acid sequences are 87.6% identical with 42 amino acid changes, 33 of which occur in the first exon. Although the UO gene is expressed exclusively within the cells of the Malpighian tubules in both of these species, the temporal patterns of UO gene activity during development are markedly different. UO enzyme activity, UO protein, and UO mRNA are found in the third instar larva and adult of D. melanogaster but only in the adult stage of D. pseudoobscura. The intronic sequences and the extragenic 5′ and 3′ flanking regions of the D. pseudoobscura and D. melanogaster UO genes are highly divergent with the exception of eight small islands of conserved sequence along 772 by 5′ of the UO protein-coding region. These islands of conserved sequence are possible UO cis-acting regulatory elements as they reside along the 5′ flanking DNA of the D. melanogaster UO gene that is capable of conferring a wild-type D. melanogaster pattern of UO regulation on a UO-lacZ fusion gene.
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  • 55
    ISSN: 1432-1432
    Keywords: Drosophila melanogaster ; Transposable element ; Mobilization ; Genomic stress ; Virus
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract To analyze the behavior of endogenous transposable elements under genomic stress, aDrosophila melanogaster inbred line was submitted to three kinds of viral perturbations. First, a retroviral plasmid containing the avian Rous Associated Virus type 2 (RAV-2) previously deleted for the viral envelope coding gene (env) was introduced by P element transformation into theDrosophila genome. An insertion of this avian retroviral sequence was detected byin situ hybridization in site 53C on polytene chromosome arm 2R. Second,Drosophila embryos were injected with RAV-2 particles produced by cell culture after transfection with the retroviral plasmid. Third, theDrosophila melanogaster inbred line was stably infected by the sigma native virus. It appears that neither the offspring of the flies in which the viral DNA was found integrated nor those from the infected sigma flies showed copia or mdgl element mobilization. Injection of the avian RAV-2 particles led, however, to the observation of somatic transpositions of mdgl element on the 2L chromosome, the copia element insertion pattern remaining stable. Thus, endogenous transposable elements show more instability in sublines injected with exogenous viral particles than in a transgenic subline containing a foreign viral insert, all transposable elements not being equally sensitive to such genomic stress.
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  • 56
    ISSN: 1432-1351
    Keywords: Electric fish ; Pacemaker ; GABA ; Glutamate ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract The medullary pacemaker nucleus of Hypopomus triggers each electric organ discharge (EOD) by a single command pulse. It consists of electrotonically coupled ‘pacemaker’ cells, which generate the rhythm, and ‘relay’ cells, which follow the pacemaker cells and excite the spinal motoneurons of the electric organ. The pacemaker cells receive two inputs from the complex of the diencephalic prepacemaker nucleus (PPn), a GABA-ergic inhibition and a glutamatergic excitation. Relay cells, on the other hand, receive two glutamatergic inputs, one from a subnucleus of the PPn, the PPn-C, and a second from the sublemniscal prepacemaker nucleus (SPPn). We have labelled afferents to the pacemaker nucleus by injecting HRP to specific sites of the prepacemaker complex. By using immunogold-labelled antibodies and en-grid staining techniques, we demonstrated GABA and glutamate immunoreactivity in labelled synaptic profiles of ultra-thin sections of the pacemaker nucleus. The two types of synapses were interspersed on the surfaces of pacemaker cells, with GABA-immunoreactive synapses apparently representing the GABA-mediated input of the ‘PPn-I’, an inhibitory subdivision of the PPn, and glutamate-immunoreactive synapses representing the input of the ‘PPn-G’, an excitatory subdivision of the PPn. Only glutamate-immunoreactive synapses were found on relay cells.
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  • 57
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    Journal of comparative physiology 186 (2000), S. 347-357 
    ISSN: 1432-1351
    Keywords: Key words Crustacean ; Sensorimotor ; Ultrastructure ; Multilamellar sheath ; Myelinated axons
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract Speed of nerve impulse conduction is greatly increased by myelin, a multi-layered membranous sheath surrounding axons. Myelinated axons are ubiquitous among the vertebrates, but relatively rare among invertebrates. Electron microscopy of calanoid copepods using rapid cryofixation techniques revealed the widespread presence of myelinated axons. Myelin sheaths of up to 60 layers were found around both sensory and motor axons of the first antenna and interneurons of the ventral nerve cord. Except at nodes, individual lamellae appeared to be continuous and circular, without seams, as opposed to the spiral structure of vertebrate and annelid myelin. The highly organized myelin was characterized by the complete exclusion of cytoplasm from the intracellular spaces of the cell generating it. In regions of compaction, extracytoplasmic space was also eliminated. Focal or fenestration nodes, rather than circumferential ones, were locally common. Myelin lamellae terminated in stepwise fashion at these nodes, appearing to fuse with the axolemma or adjacent myelin lamellae. As with vertebrate myelin, copepod sheaths are designed to minimize both resistive and capacitive current flow through the internodal membrane, greatly speeding nerve impulse conduction. Copepod myelin differs from that of any other group described, while sharing features of every group.
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  • 58
    ISSN: 1432-1432
    Keywords: Armadillo ; β-catenin ; Plakoglobin ; Drosophila melanogaster ; Musca domestica ; Nucleotide sequence ; Evolutionary comparison
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Segmental pattern in Drosophila melanogaster is set up via a set of cell-cell interactions mediated by the products of the segment polarity genes. Among these is the armadillo gene, whose product seems to be required for the reception of an intercellular signal encoded by the wingless gene. As part of our effort to relate the structure of the armadillo protein to its function within the cell, we have examined the evolutionary conservation of the armadillo gene during insect evolution. We have cloned the armadillo gene from the housefly, Musca domestica, which diverged from Drosophila 100 million years ago. The Musca protein is 97.5% identical to that in Drosophila, while the noncoding sequences have diverged extensively. This remarkable degree of conservation at the protein level is mirrored in the expression pattern of the armadillo protein. Antibodies against the Drosophila protein cross-react with a Musca protein of the appropriate size. We have also used these antibodies to show that the Musca armadillo protein has a pattern of expression in larval and adult tissues similar to that of Drosophila armadillo. We discuss the implications of conservation of structure and expression for the cellular role of the armadillo protein and its mammalian homologs.
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  • 59
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    Journal of molecular evolution 31 (1990), S. 389-401 
    ISSN: 1432-1432
    Keywords: period gene ; Nuclear vs mitochondrial silent substitution rates ; Amino acid replacement ; Drosophila yakuba ; Drosophila melanogaster
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Two nuclear genes fromDrosophila yakuba were cloned, the orthologue of theDrosophila melanogaster period (per) clock gene and the orthologue of an unnamedD. melanogaster gene adjacent toper, which encodes a 0.9-kb RNA transcript. The DNA and presumed protein sequences of both genes are presented and compared with their orthologues inD. melanogaster. Consistent with theper orthologues described in otherDrosophila species, some parts of theper gene have accumulated nonsynonymous substitutions at a much higher rate than others. This contrasts markedly with the evenly distributed amino acid replacements observed in the protein encoded by the adjacent gene. The level of synonymous and nonsynonymous substitutions betweenD. yakuba andD. melanogaster per were compared in small subsections across the gene. The results suggest that the divergence observed in the less well-conserved regions of theper protein is principally due to reduced selective constraint, although the limitations of the method used prevent positive selection acting upon a small proportion of sites being ruled out. The level of silent substituion observed in both of these nuclear genes is very similar to the level of silent substitution previously reported betweenD. melanogaster andD. yakuba mitochondrial genes, confirming several indirect studies, which have suggested that, in contrast to the case in mammals, silent sites are evolving at similar rates in mitochondrial and nuclear genes ofDrosophila.
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  • 60
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    Journal of molecular evolution 39 (1994), S. 466-472 
    ISSN: 1432-1432
    Keywords: P element ; Transposition ; Copynumber regulation ; Drosophila melanogaster
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Six highly inbred lines of Drosophila melanogaster extracted from an M′ strain (in the P/M system of hybrid dysgenesis) were studied for the evolution of the number and chromosomal location of complete and defective P elements through generations 52–200. These lines possessed full-sized P elements but differed in their cytotype (M or P). Three lines with P cytotype and full-sized P elements at site 1A had a constant P copy number over generations with low rates of insertion and excision. Three lines with M cytotype and at least one full-sized P element accumulated P copies over the generations and reached a plateau near generation 196, at which rates of transposition and excision were equal to 1.2 × 10−3 to 3 × 10−3 events per element per generation. At that time these three lines still presented an M cytotype, produced transposase, and were able to regulate P copy number. The similarity at equilibrium between insertion and excision rates was exactly what was expected from theoretical models for a self-regulated element. The large number of generations necessary to attain the equilibrium in copy number indicates, however, that caution may be de rigueur when testing theoretical models of copy-number containment based on transposition and excision-rate comparison.
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  • 61
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    Journal of molecular evolution 41 (1995), S. 155-160 
    ISSN: 1432-1432
    Keywords: TGF-β superfamily ; decapentaplegic gene ; Drosophila melanogaster ; Schistocerca americana ; Gene comparison
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Intercellular signaling molecules of the transforming growth factor-β (TGF-β) superfamily are required for pattern formation in many multicellular organisms. The decapentaplegic (dpp) gene of Drosophila melanogaster has several developmental roles. To improve our understanding of the evolutionary diversification of this large family we identified dpp in the grasshopper Schistocerca americana. S. americana diverged from D. melanogaster approximately 350 million years ago, utilizes a distinct developmental program, and has a 60-fold-larger genome than D. melanogaster. Our analyses indicate a single dpp locus in D. melanogaster and S. americana, suggesting that dpp copy number does not correlate with increasing genome size. Another TGF-β superfamily member, the D. melanogaster gene 60A, is also present in only one copy in each species. Comparison of homologous sequences from D. melanogaster, S. americana, and H. sapiens, representing roughly 900 million years of evolutionary distance, reveals significant constraint on sequence divergence for both dpp and 60A. In the signaling portion of the dpp protein, the amino acid identity between these species exceeds 74%. Our results for the TGF-β superfamily are consistent with current hypotheses describing gene duplication and diversification as a frequent response to high levels of selective pressure on individual family members.
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  • 62
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    Journal of molecular evolution 38 (1994), S. 232-240 
    ISSN: 1432-1432
    Keywords: Drosophila melanogaster ; P-element evolution ; Scaptomyza pallida ; Immobile P-elements ; Pericentromeric heterochromatin
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract We report the cloning and analysis of a sample representative of all P-elements from Scaptomyza pallida. We have compared four independent stocks of this species, using Southern blot and in situ hybridization experiments to examine the number, structure, and distribution of P-elements. All four stocks give similar results: they contain about 15 P-elements including three to four full-length elements as well as shorter, deleted elements. All elements are divergent from one another and most of them appear to be immobile since they are located at identical positions in the genomes of independent stocks. These data indicate that P-elements are old components of the S. pallida genome. Moreover, the presence of P-sequences in species closely related to S. pallida suggests that they have had a long evolutionary history in the Scaptomyza genus. We have also found that most P-elements of S. pallida are located in the pericentromeric heterochromatin. This corroborates other studies which show that in the course of their evolution, transposable elements tend to accumulate into pericentromeric heterochromatin, where they become immobile and noncoding.
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  • 63
    ISSN: 1432-2285
    Keywords: Cambial activity ; Frost hardiness ; Phenology ; Salix ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary The ultrastructure of cells in the cambial region of Salix dasyclados Wim. (clone 78056) was studied during the development of winter hardiness and the onset of cambial activity in spring. Plants were grown at relative growth rates (RG) of 8% and 12% respectively, resulting in different nitrogen content in the stems. Frost hardiness of the plants was estimated by standardized freezing tests. Plants with a higher nitrogen status ceased growth later and started re-growth earlier in spring than plants with lower nitrogen content. Differences in ability to withstand low temperatures during autumn and spring were found between plants grown in the two nutrient treatments. During the development of frost hardiness in the autumn, the number of meristematic cells in the cambial region decreased. The cessation of meristematic activity was accompanied by cell wall thickening and ultrastructural changes in the cells. Frost hardiness increased from the ability to survive -6° C in October to survival of -80° C at the beginning of December. From November to February the cambial region comprised a layer of 2–3 thick-walled cells with conspicuous ultrastructural features. Starch accumulated in plastids in September, decreased during November to March and then increased again in accordance with changes of frost hardiness. Onset of cambial activity began between the end of March and the beginning of April, as shown by increased vacuolization of meristematic cells and mitotic activity. By April, the starch content had increased and lipolysis was observed. Frost hardiness had decreased, and plants with low and high nitrogen content were able to survive -15° C and -10° C, respectively. After budburst, all axillary shoot parts were damaged at temperatures below-3° C.
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  • 64
    ISSN: 1432-2285
    Keywords: Conifer ; Fluoride ; Nitrogen ; Sulphur dioxide ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Effects of SO2, aqueous fluoride (NaF) and a solution of nitrogen compounds (NH4NO3) on the visible symptoms, pollutant accumulation and ultrastructure of Scots pine (Pinus sylvestris L.) and Norway spruce [Picea abies (L.) Karst.] seedlings were studied in an open-air experiment lasting for 3 consecutive years. Visible injury symptoms were most pronounced in combination exposures and whenever F was applied. Visible symptoms correlated well with needle pollutant concentrations. Exposure to NaF increased needle F contents particularly when F was applied with SO2 or NH4NO3. This suggests that a reduction in N or SO2 emissions, in F polluted areas, could improve the condition of conifers via decreased accumulation of phytotoxic F in the needles. Norway spruce needles accumulated 2–10 times as much S and F as those of Scots pine. Microscopic observations showed various changes in the needle mesophyll cell ultrastructure. In both species, exposure to SO2 increased significantly the amount of cytoplasmic vacuoles, suggesting detoxification of excess sulphate or low pH. F treatments resulted in a significant enlargement of plastoglobuli in Scots pine and a darkening of plastoglobuli in Norway spruce. All exposures enhanced the accumulation of lipid bodies. An increased portion of translucent plastoglobuli was most pronounced in N treatments. Many of the ultrastructural changes and visible symptoms appeared only as number of years exposed increased, indicating that long-term experiments are needed. Both visible symptoms and ultrastructural changes pointed to the more pronounced sensitivity of Norway spruce compared to Scots pine. Ultrastructural results mostly supported earlier qualitative observations of F, N and SO2 effects on needle mesophyll cell ultrastructure. However, no reduction of thylakoids in SO2 containing exposure or curling of thylakoids in F exposure could be detected in the present study.
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  • 65
    ISSN: 1572-9737
    Keywords: allozymes ; effective population size ; Drosophila melanogaster ; genetic diversity ; inversions
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Preservation of genetic diversity is of fundamental concern toconservation biology, as genetic diversity is required for evolutionarychange. Predictions of neutral theory are used to guide conservationactions, especially genetic management of captive populations ofendangered species. Loss of heterozygosity is predicted to be inverselyrelated to effective population size. However, there is controversy asto whether allozymes behave as predicted by this theory. Loss of geneticdiversity for seven allozyme loci, chromosome II inversions andmorphological mutations was investigated in 23 Drosophilamelanogaster populations, maintained at effective population sizesof 25 (8 replicates), 50 (6), 100 (4), 250 (3) and 500 (2) for 50generations. Allozyme genetic diversity (heterozygosity, percentpolymorphism and allelic diversity), inversions and morphologicalmutations were all lost at greater rates in smaller than largerpopulations. Conservation concerns about loss of genetic diversity insmall populations are clearly warranted. Across our populations, loss ofallozyme heterozygosity over generations 0–24, 0–49 and25–49 did not differ from the predictions of neutral theory. Thetrend in deviations was always in the direction expected withassociative overdominance. Our results support the use of neutral theoryto guide conservation actions, such as the genetic management ofendangered species in captivity.
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  • 66
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    Mycopathologia 59 (1976), S. 117-123 
    ISSN: 1573-0832
    Keywords: Ultrastructure ; Zygospore ; Mycorrhizal fungus ; Flaming crown
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract The ultrastructural organization of the spores of the sporocarp of Endogone flammicorona was studied. Two types of organization are described. Initially the spore possessed a vacuolate protoplasm and was bound by two cell wall layers. The spore was surrounded by a hyphal mantle formed of a sheet of vacuolized hyphae with uniformly thin walls. Secondly, although the ultrastructural features of the spore appeared the same, it was now surrounded by a hyphal mantle with unevenly thickened walls (i. e., the so-called flaming crown) due to the gradual and irregular deposition of granules and lamellae. This crown gives the spore its most commonly observed morphological feature and is the preminent character employed taxonomically to speciate Endogone flammicorona Trappe & Gerdemann.
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  • 67
    ISSN: 1573-0832
    Keywords: Capsule ; Cryptococcus neoformans ; Deep-etching ; Quick-freezing ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract The three-dimensional ultrastructure ofCryptococcus neoformans was studied by quick-freezing and deep-etching (QF-DE) method.C. neoformans, strain CDC551, was cultured on agar. The viable yeast cells (107 cells) were inoculated into each mouse from the tail vein. Three weeks after the inoculation, the brains of the mice were perfused with fixatives, quickly frozen, freeze-fractured, deeply etched and rotary shadowed with platinum and carbon. In addition, the viable cells ofC. neoformans on agar were picked up and quickly frozen, and replica membranes were prepared as described above. The ultrastructure ofC. neoformans was three-dimensionally demonstrated by the QF-DE method. The capsule was composed of fine meshworks of microfibrils (10–13 nm in diameter), which were directly attached to the cell walls. The capsule of the in vivo yeasts (yeast cells in the brain lesion) was thicker than that of the in vitro yeasts (yeast cells on agar culture). At the outer part of the cell wall, a particle-accumulating layer was observed. This layer in vivo was thicker than that in vitro. Occasionally, the yeast cells were ingested by phagocytes in the mouse brain. Although the cytoplasm of such yeast cells was destroyed, the capsular meshworks were well preserved. The ultrastructure of the capsule was the same both in cultured and phagocytized yeasts in the cystic lesions of the brains. This lack of morphological changes of the capsular meshworks suggests that they are resistant to the digestion by phagocytes. This stability of capsular structures may provide one of the important pathogenic factors in cystic lesions byC. neoformans.
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  • 68
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    Mycopathologia 128 (1994), S. 181-192 
    ISSN: 1573-0832
    Keywords: Aflatoxin B1 ; Embryo ; Mature ; Ultrastructure ; Zea mays L.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract Mature maize (Zea mays L.) embryos were exposed to aflatoxin B1 (AFB1) concentrations ranging from 0.1 to 25 µg/ml for 9 days. With increasing toxin concentration above 2 µg/ml, primary root elongation of germinated embryos was progressively inhibited, to reach a maximum value of 81% at 25 µ/ml toxin. An ultrastructural investigation of the subcellular alterations induced following toxin exposure provided evidence of deteriorative changes in several compartments of the plant cell. Alteration in membrane integrity (e.g., the tonoplast, plasmalemma and inner mitochondrial membrane) was a frequent feature of many cells. Apparent fusion of vacuoles, incorporation of cytoplasmic components into vacuoles and intravacuolar membrane whorls might be interpreted as deteriorative alterations. The results are discussed in the light of ultrastructural findings for other plant systems exposed to similar AFB1 concentrations, as well as findings for animal systems.
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  • 69
    ISSN: 0931-1890
    Keywords: Key words Conifer ; Fluoride ; Nitrogen ; Sulphur dioxide ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract  Effects of SO2, aqueous fluoride (NaF) and a solution of nitrogen compounds (NH4NO3) on the visible symptoms, pollutant accumulation and ultrastructure of Scots pine (Pinus sylvestris L.) and Norway spruce [Picea abies (L.) Karst.] seedlings were studied in an open-air experiment lasting for 3 consecutive years. Visible injury symptoms were most pronounced in combination exposures and whenever F was applied. Visible symptoms correlated well with needle pollutant concentrations. Exposure to NaF increased needle F contents particularly when F was applied with SO2 or NH4NO3. This suggests that a reduction in N or SO2 emissions, in F polluted areas, could improve the condition of conifers via decreased accumulation of phytotoxic F in the needles. Norway spruce needles accumulated 2 – 10 times as much S and F as those of Scots pine. Microscopic observations showed various changes in the needle mesophyll cell ultrastructure. In both species, exposure to SO2 increased significantly the amount of cytoplasmic vacuoles, suggesting detoxification of excess sulphate or low pH. F treatments resulted in a significant enlargement of plastoglobuli in Scots pine and a darkening of plastoglobuli in Norway spruce. All exposures enhanced the accumulation of lipid bodies. An increased portion of translucent plastoglobuli was most pronounced in N treatments. Many of the ultrastructural changes and visible symptoms appeared only as number of years exposed increased, indicating that long-term experiments are needed. Both visible symptoms and ultrastructural changes pointed to the more pronounced sensitivity of Norway spruce compared to Scots pine. Ultrastructural results mostly supported earlier qualitative observations of F, N and SO2 effects on needle mesophyll cell ultrastructure. However, no reduction of thylakoids in SO2 containing exposure or curling of thylakoids in F exposure could be detected in the present study.
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  • 70
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    Development genes and evolution 182 (1977), S. 69-74 
    ISSN: 1432-041X
    Keywords: Drosophila melanogaster ; Male foreleg disk ; Capacity of transdetermination
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    Topics: Biology
    Notes: Summary In the male foreleg disk ofDrosophila melanogaster the cells capable of transdetermination are clustered in a specific region within the upper half of the disk. Cells outside this region cannot transdetermine under any of the experimental conditions thus far applied. Transdetermination occurs when cells capable of transdetermination are stimulated to a certain extent of additional proliferation. This can be achieved either by exposing these cells at a wound surface of an intact fragment, or by dissociation.
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  • 71
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    Development genes and evolution 187 (1979), S. 151-165 
    ISSN: 1432-041X
    Keywords: Oogenesis ; Embryogenesis ; Two-dimensional gels ; Protein synthesis ; Drosophila melanogaster
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    Topics: Biology
    Notes: Summary Protein synthesis in egg follicles and blastoderm embryos ofDrosophila melanogaster has been studied by means of two-dimensional gel electrophoresis. Up to 400 polypeptide spots have been resolved on autoradiographs. Stage 10 follicles (for stages see King, 1970) were labelled in vitro for 10 to 60 min with35S-methionine and cut with tungsten needles into an anterior fragment containing the nurse cells and a posterior fragment containing the oocyte and follicle cells. The nurse cells were found to synthesize a complex pattern of proteins. At least two proteins were detected only in nurse cells but not in the oocyte even after a one hour labelling period. Nurse cells isolated from stages 9, 10 and 12 follicles were shown to synthesize stage specific patterns of proteins. Several proteins are synthesized in posterior fragments of stage 10 follicles but not in anterior fragments. These proteins are only found in follicle cells. No oocyte specific proteins have been detected. Striking differences between the protein patterns of anterior and posterior fragments persist until the nurse cells degenerate. In mature stage 14 follicles, labelled in vivo, no significant differences in the protein patterns of isolated anterior and posterior fragments could be detected; this may be due to technical limitations. At the blastoderm stage localized synthesis of specific proteins becomes detectable again. When blastoderm embryos, labelled in vivo, are cut with tungsten needles and the cells are isolated from anterior and posterior halves, differences become apparent. The pole cells located at the posterior pole are highly active in protein synthesis and contribute several specific proteins which are found exclusively in the posterior region of the embryo. In this study synthesis of specific proteins could only be demonstrated at those developmental stages which are characterized by the presence of different cell types within the egg chamber, while no differences were detected when stage 14 follicles were cut and anterior and posterior fragments analyzed separately. The differences in the pattern of protein synthesis by pole cells and blastoderm cells indicate that even the earliest stages of determination are reflected by marked changes at the biochemical level.
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  • 72
    ISSN: 1432-041X
    Keywords: Ultrastructure ; Scanning cytophotometry ; Chromatin ; Chondrocytes ; Regeneration
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    Topics: Biology
    Description / Table of Contents: Résumé Les cellules cartilagineuses des membres postérieurs deTriturus cristatus en régénération après amputation, ont été étudiées en microscopie électronique et par cytophotométrie à balayage. Nous nous sommes intéressés à la structure et à la distribution de la chromatine mais aussi à différents organites cytoplasmiques. Dans l'étude de cytophotométrie à balayage, la chromatine a été considérée à travers son constituant majeur, l'ADN, coloré par la réaction de Feulgen. Au cours de la régénération du membre, l'hétérochromatine initialement condensée, essentiellement accolée à la membrane nucléaire se décondense. Les vacuoles du cytoplasme, caractéristiques des animaux âgés par rapport aux animaux jeunes, disparaissent, les mitochondries et le reticulum endoplasmique rugueux deviennent plus abondants. Les caractéristiques nucléaires de l'activation cellulaire apparaissent précocement, précédent les modifications cytoplasmiques et conduisent à des cellules en tous points identiques aux cellules d'animaux jeunes en dehors de tout processus régénératif. Cette phase d'euchromatisation et de restructuration cytoplasmique est peut-être nécessaire à l'accroissement d'activité métabolique et à la division cellulaire qui suivent. Son déroulement peut expliquer tout au moins le ralentissement de la régénération observé chez les animaux âgés par rapport aux animaux jeunes.
    Notes: Summary Cartilaginous cells of aged newts (Triturus cristatus) were studied during hind limb regeneration. The electron microscope was used to study the structure and distribution of chromatin in the cell nuclei, while the DNA content of the chromatin was measured by means of a scanning cytophotometer. Changes in the ultrastructure of the cytoplasm during regeneration were also studied. It was observed that the structure and distribution of chromatin in the activated cell is greatly modified. In the non-activated cell of the aged newt, the chromatin is found highly condensed and distributed peripherally close to the nuclear membrane. In contrast, in the activated cells, the chromatin is much less condensed and is distributed throughout the nucleus. Moreover, cytoplasmic vacuoles, found only in the non-activated aged cells, disappear and an increase in the mitochondria and rough endoplasmic reticulum is also observed. Changes in the nuclear structure are observed prior to the cytoplasmic modifications. It is interesting to note that the process of activation induces structural changes in the aged cells which make these cells appear to be structurally identical to the young cells. This process of rejuvenation takes 3–5 days in the newt. We suggest that these structural changes of the chromatin and cytoplasm in the aged cells are necessary to increase the metabolic activity which precedes cell division. It may also explain why regeneration takes a longer time in the aged animals than in the young ones.
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    Development genes and evolution 191 (1982), S. 257-263 
    ISSN: 1432-041X
    Keywords: Juvenile hormone ; Precocene ; Drosophila melanogaster ; Oocyte degeneration
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    Topics: Biology
    Notes: Summary It is known from previous work that juvenile hormone (JH) is required to initiate vitellogenin uptake into maturing oocytes ofDrosophila melanogaster, but additional requirements for this hormone during oocyte maturation have not been fully understood. To determine if early vitellogenic oocytes (stages 8 and 9) require JH for continued development, these oocytes were transplanted toDrosophila female and male hosts which were rendered deficient in JH by three methods. Implanted stage 9 and usually stage 8 oocytes were found to degenerate in JH-deficient hosts unless ZR-515, a JH analogue, was applied to the host shortly after implantation. These results were confirmed during in situ ovary development. JH deficiency was produced in gravid females, and ovaries examined at subsequent time intervals were found to be deficient in stage 8–10 oocytes as early as 6 h after treatment. Degenerating oocytes corresponding to these stages were commonly found. ZR-515 prevented oocyte degeneration during at least the first 8 h and continued to support stage 8–10 oocyte development 24 h after application to these females. The results suggest that JH is required not only for initiation but also for continuation of vitellogenin uptake and oocyte development.
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  • 74
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    Development genes and evolution 192 (1983), S. 42-44 
    ISSN: 1432-041X
    Keywords: Chick embryo ; Gastrulation ; Adenylate cyclase ; cAMP phosphodiesterase ; Ultrastructure
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    Topics: Biology
    Notes: Summary The ultrastructural localization of adenylate cyclase (E.C. 4.6.1.1.) and cAMP phosphodiesterase (PDE) (E.C. 3.1.4.17.) in the ectoderm of the developmental stage 4 chick embryo was studied. Adenylate cyclase was localized in the lateral surfaces of the ectodermal cells. In the primitive streak cells the enzymatic activity was observed on all the lateral surfaces, whereas in the periphery of the blastoderm the reaction product was localized in the apical parts of the lateral plasma membranes only. cAMP PDE localized in the apical cytoplasm of the ectodermal cells, with highest activity in the globular projections.
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  • 75
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    Development genes and evolution 192 (1983), S. 366-368 
    ISSN: 1432-041X
    Keywords: Drosophila melanogaster ; Wing discs ; 20-Hydroxyecdysone
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    Topics: Biology
    Notes: Summary Full wing disc evagination requires about 10 h of continuous exposure to 20-hydroxyecdysone. The synthesis of two polypeptides is increased when wing discs are subjected to short exposure (4 h) to the hormone, and their synthesis is dependent on hormone. A second group of proteins increased in synthesis only after longer hormonal treatment (12 h); however, the increased synthesis of these proteins can be induced by withdrawing hormone after short exposure. The results of this study are consistent with the model of sequential gene activation by 20-hydroxyecdysone proposed by Ashburner et al. (1974).
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  • 76
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    Development genes and evolution 194 (1985), S. 236-246 
    ISSN: 1432-041X
    Keywords: Drosophila melanogaster ; engrailed ; Selector gene ; Genetic complementation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary In 1975, Morata and Lawrence proposed that theengrailed (en) locus was a selector gene that controlled the different pathways of development followed by anterior and posterior compartments. This hypothesis assumed that the phenotype ofen 1 flies results from partial inactivity of theen + product. However, the mutant phenotype ofen 1/DF(2R)en − is weaker thanen 1/en 1. This implies that the partial P→A transformation ofen 1 does not result primarily from reduction inen + activity. Heterozygotes betweenl(2) en alleles andDf(2R)en − deletions express a similar phenotype of fused embryonic segments to that described by Nüsslein-Volhard and Wieschaus, and also by Kornberg, forl(2) en homozygoes. By this criterion, the lethal phenotype results from partial or complete lack ofen _ activity. Despite this, the1(2) en alleles give only a weak P→A transformation, whether recovered as embryonic lethals or by failure to complementen 1. They appear to define only one locus and, with the exception ofen 1, the available genetic date suggest that the complementation pattern at this locus is simple. Thus, it is unlikely thatengrailed is the sole determinant of the A/P compartment separation. It might be one of a number of loci that affect the alternative pathways followed by anterior and posterior compartments.
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  • 77
    ISSN: 1432-041X
    Keywords: Drosophila melanogaster ; Imaginal discs ; Lethal mutants ; Homeosis
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    Topics: Biology
    Notes: Summary The ash-1 locus is in the proximal region of the left arm of the third chromosome of Drosophila melanogaster and the ash-2 locus is in the distal region of the right arm of the third chromosome. Mutations at either locus can cause homeotic transformations of the antenna to leg, proboscis to leg and/or antenna, dorsal prothorax to wing, first and third leg to second leg, haltere to wing, and genitalia to leg and/or antenna. Mutations at the ash-1 locus cause, in addition, transformations of the posterior wing and second leg to anterior wing and second leg, respectively. A similar spectrum of transformations is caused by mutations at yet another third chromosome locus, trithorax. One extraordinary aspect of mutations at all three of these loci is that they cause such a wide variety of transformations. For mutations at both of the loci that we have studied the expression of the homeotic phenotype is both disc-autonomous (as shown by injecting mutant discs into metamorphosing larvae) and cell autonomous (as shown by somatic recombination analysis). The original mutations which identified these two loci, although lethal, manifest variable expressivity and incomplete penetrance of the homeotic phenotype suggesting that they are hypomorphic. The phenotype of double mutants which were synthesized by combining different pairs of those original mutations manifest for two of the four pairs a greater degree of expressivity and slightly more penetrance of the homeotic transformations. This mutual enhancement suggests that the products of both loci interact in the same process. A third double mutant expresses a discless phenotype. Additional alleles have been recovered at both the ash-1 and the ash-2 loci. Some of these alleles as homozygotes or transheterozygotes express the wide range of transformations revealed first by double mutants. One of the alleles at the ash-1 locus when homozygous and several transheterozygous pairs can cause either the homeotic transformation of discs or the absence of those discs. The fact that these two defects, absence of specific discs and homeotic transformations of those same discs can be caused by mutations within a single gene suggests that the activity of the product of this gene is essential for normal imaginal disc cell proliferation. Loss of that activity leads to the absence of discs, whereas, reduction of that activity leads to homeotic transformations.
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    Development genes and evolution 196 (1987), S. 473-485 
    ISSN: 1432-041X
    Keywords: Drosophila melanogaster ; Proliferation ; Neuroblasts
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The pattern of neuroblast divisions was studied in thoracic and abdominal neuromeres of wild-type Drosophila melanogaster embryos stained with a monoclonal antibody directed against a chromatin-associated antigen. Since fixed material was used, our conclusions are based upon the statistical evaluation of a large number of accurately staged embryos, covering the stages between the formation of the cephalic furrow up to shortened germ band. Our observations point to a rather stereotypic pattern of proliferation, consisting of several parasynchronous cycles of division. The data suggest that all SI neuroblasts divide at least eight times, all SII neuroblasts six or seven times and all SIII neuroblasts at least five times. This conclusion is based on the mapping of mitotic neuroblasts and is supported by the progressive reduction of the neuroblast volume and by the results of cell countings performed on embryos of increasing age. No conclusive evidence was obtained concerning the fate of the neuroblasts after their last mitosis, i.e. it cannot be decided whether the neuroblasts degenerate or become incorporated as inconspicuous cells in the larval ventral cord. The duration of the cycles of division of the neuroblasts was found to be 40–50 min each, while in the case of ganglion mother cells about 100 min are required to complete one cell cycle.
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    Development genes and evolution 199 (1991), S. 423-426 
    ISSN: 1432-041X
    Keywords: Oogenesis ; Accessory nuclei ; Developmental gradients ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary In the oocytes ofTenthredo olivacea, accessory nuclei (AN) are formed by budding from the nuclear envelope of the oocyte nucleus. Newly formed AN contain electron-dense material of nuclear origin and are surrounded by a double envelope devoid of pores. Such structures are subsequently transported to the peripheral ooplasm (periplasm), where they grow to reach a final diameter of 5 µm. In the envelopes of advanced AN nuclear pores arise. Through these pores “nuage” material is extruded into the surrounding periplasm. These findings are discussed with respect to a possible involvement of AN in the establishment of developmental gradients in hymenopteran oocytes.
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    Development genes and evolution 202 (1993), S. 276-295 
    ISSN: 1432-041X
    Keywords: Embryogenesis ; Muscle development ; Drosophila melanogaster ; Genetic analysis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract We have begun a genetic analysis to dissect the process of myogenesis by surveying the X chromosome of Drosophila melanogaster for mutations that affect embryonic muscle development. Using polarised light microscopy and antibody staining techniques we analysed embryos hemizygous for a series of 67 deletion mutations that together cover an estimated 85% of the X chromosome, or 16.5% of the genome. Whereas the mature wild type embryo has a regular array of contractile muscles that insert into the epidermis, 31 of the deletion mutants have defects in muscle pattern, contractility or both, that cannot be attributed simply to epidermal defects and identify functions required for wild type muscle development. We have defined mutant pattern phenotypes that can be described in terms of muscle absences, incomplete myoblast fusion, failure of attachment of the muscle to the epidermis or mispositioning of attachment sites. Thus muscle development can be mutationally disrupted in characteristic and interpretable ways. The areas of overlap of the 31 deletions define 19 regions of the X chromosome that include genes whose products are essential for various aspects of myogenesis. We conclude that our screen can usefully identify loci coding for gene products essential in muscle development.
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    Development genes and evolution 203 (1993), S. 151-158 
    ISSN: 1432-041X
    Keywords: Drosophila melanogaster ; Pattern formation ; Neurogenesis ; Peripheral nervous system ; Microchaetes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The small bristles (microchaetes) on the thorax of adult Drosophila are evenly spaced. We have analysed the development of this pattern using the enhancer trap line A101 where bacterial lacZ is expressed in the microchaete sensory mother cells (SMCs) and their progeny. We observed that the precursor cells appear in a stereotyped pattern of rows. Within each row, however, SMCs appear neither at a time nor in a restricted sequence: new SMCs are continuously intercalated between pre-existing SMCs until the distance between consecutive SMCs does not exceed a few cell diameters. In large individuals, additional SMCs may occasionally appear after the completion of the rows, in the largest empty spaces between the preexisting SMCs.
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    Development genes and evolution 204 (1994), S. 112-117 
    ISSN: 1432-041X
    Keywords: Drosophila melanogaster ; Drosophila simulans ; Hybrids ; Clonal analysis ; Lhr
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract We have analysed the viability of cellular clones induced by mitotic recombination in Drosophila melanogaster/D. simulans hybrid females during larval growth. These clones contain a portion of either melanogaster or simulans genomes in homozygosity. Analysis has been carried out for the X and the second chromosomes, as well as for the 3L chromosome arm. Clones were not found in certain structures, and in others they appeared in a very low frequency. Only in abdominal tergites was a significant number of clones observed, although their frequency was lower than in melanogaster abdomens. The bigger the portion of the genome that is homozygous, the less viable is the recombinant melano-gaster/simulans hybrid clone. The few clones that appeared may represent cases in which mitotic recombination took place in distal chromosome intervals, so that the clones contained a small portion of either melanogaster or simulans chromosomes in homozygosity. Moreover, Lhr, a gene of D. simulans that suppresses the lethality of male and female melanogaster/simulans hybrids, does not suppress the lethality of the recombinant melanogaster/simulans clones. Thus, it appears that there is not just a single gene, but at least one per tested chromosome arm (and maybe more) that cause hybrid lethality. Therefore, the two species, D. melanogaster and D. simulans, have diverged to such a degree that the absence of part of the genome of one species cannot be substituted by the corresponding part of the genome of the other, probably due to the formation of co-adapted gene complexes in both species following their divergent evolution after speciation. The disruption of those coadapted gene complexes would cause the lethality of the recombinant hybrid clones.
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    Cellular and molecular life sciences 41 (1985), S. 1607-1609 
    ISSN: 1420-9071
    Keywords: Neuronal specificity ; sensory projections ; serial homology ; ectopic transplantation ; Drosophila melanogaster
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Owing to a new transplantation technique, we have been able to study the sensory projections of homologous and heterologous appendages grafted to the same abdominal site inD. melanogaster. Axons from homologous transplants exhibit similar terminal patterns, whereas those from heterologous transplants do not. It is suggested that ectopic sensory axons specifically recognized central areas and pathways occupied by axons from homologous appendages.
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    Cellular and molecular life sciences 41 (1985), S. 57-58 
    ISSN: 1420-9071
    Keywords: Drosophila melanogaster ; aldehyde dehydrogenase ; mitochondria
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Subcellular fractionation by differential centrifugation confirms the presence of aldehyde dehydrogenase inD. melanogaster. It is found principally in the heavy mitochondrial fraction.
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    Cellular and molecular life sciences 41 (1985), S. 127-129 
    ISSN: 1420-9071
    Keywords: Drosophila melanogaster ; second chromosome ; drastics ; genetic load ; population size
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The effect of 750 second chromosomes ofDrosophila melanogaster on viability was studied. 19.3% of them proved letal or semilethal (=drastics) in homozygous condition. Compared to data obtained in previous years at the same sampling site, a significant frequency decrease of drastics during the past decade could be observed. The dynamic processes taking place in the Korean wild populations ofD. melanogaster are discussed.
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    Cellular and molecular life sciences 41 (1985), S. 1474-1476 
    ISSN: 1420-9071
    Keywords: Mobile elements ; inbreeding ; in situ hybridization ; Drosophila melanogaster
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The location of the mobile element mdg-1 was determined by in situ hybridization in salivary gland chromosomes ofDrosophila melanogaster. The locations of mdg-1 are nonrandom and some ‘hot spots’ exist. Moreover, the spectra of mdg-1 locations vary with the viability values of the families from which the larvae originated. This suggests that particular frequency spectra are associated with lethality resulting from inbreeding.
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  • 87
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    Cellular and molecular life sciences 42 (1986), S. 1051-1053 
    ISSN: 1420-9071
    Keywords: Age-structured population ; age-related mating success ; assortative mating ; generation overlap ; Drosophila melanogaster
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    Topics: Biology , Medicine
    Notes: Summary A series of experiments on age-related mating success and productivity provides evidence for assortative mating among three out of four age-classes inD. melanogaster. The preferred mating does not always result in the highest productivity. Three age classes of males contribute to reproduction while only females of the youngest age-class are involved. The progeny size is more affected by the age of the females than that of males. It is assumed that these findings must have important implications for generation overlap in natural populations.
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  • 88
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    Cellular and molecular life sciences 45 (1989), S. 983-985 
    ISSN: 1420-9071
    Keywords: Drosophila melanogaster ; sterol metabolism ; phytosterols ; dealkylation ; desmosterol ; sitosterol ; radiolabeled sterols
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Drosophila melanogaster was unable to dealkylate and convert [14C]sitosterol to cholesterol and no evidence was found for conversion of [14C]desmosterol to cholesterol. Therefore,D. melanogaster is incapable of dealkylating and converting C28 and C29 phytosterols to cholesterol.
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  • 89
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    Cellular and molecular life sciences 51 (1995), S. 744-748 
    ISSN: 1420-9071
    Keywords: Morphometry ; geographic races ; chromosome transfers ; Drosophila melanogaster ; natural populations
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract The genetic basis of three morphological traits (ovariole number, sternopleural bristle number and wing length) ofDrosophila melanogaster has been investigated in natural populations that show great differences in these traits, i. e. Bordeaux (France) and Loua (Congo). F1 and F2 crosses, and chromosome substitutions between these two populations, were analysed. Maternal and/or X chromosome effects were found for sternopleural bristle number and wing length. For all traits, significant effects from each of the three chromosomes were found, but in general only one or two chromosomes had a major effect. Moreover, in all cases significant interactions between chromosomes were observed, suggesting the existence of epistatic effects. Our results are discussed and compared to those obtained from the analysis of selected laboratory strains.
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  • 90
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    Development genes and evolution 206 (1996), S. 277-280 
    ISSN: 1432-041X
    Keywords: Key words Nervous system development ; Metamorphosis ; Phagocytosis ; Glial cells ; Drosophila melanogaster
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract  Using electron microscopy we demonstrate that degenerating neurons and cellular debris resulting from neuronal reorganization are phagocytosed by glial cells in the brain and nerve cord of the fruitfly Drosophila melanogaster during the first few hours following pupariation. At this stage several classes of glial cells appear to be engaged in intense phagocytosis. In the cell body rind, neuronal cell bodies are engulfed and phagocytosed by the same glial cells that enwrap healthy neurons in this region. In the neuropil, cellular debris in tracts and synaptic centres resulting from metamorphic re-differentiation of larval neurons is phagocytosed by neuropil-associated glial cells. Phagocytic glial cells are hypertrophied, produce large amounts of lysosome-like bodies and contain a large number of mitochondria, condensed chromatin bodies, membranes and other remains from neuronal degeneration in phagosomes.
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    Development genes and evolution 208 (1998), S. 106-112 
    ISSN: 1432-041X
    Keywords: Key words Apoptosis ; Oogenesis ; Nurse cells ; Drosophila melanogaster
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract  In Drosophila a remarkable feature of oogenesis is the regression of the nurse cells after dumping their cytoplasmic contents into the oocyte. We have studied the nature of this process at the late stages of egg chamber development. In egg chambers DAPI staining shows highly condensed chromatin from stage 12 and TUNEL labelling shows DNA fragmentation up to stage 14. Gel electrophoresis of the end-labelled DNA, extracted from isolated egg chambers at the same stages of development, shows a ladder typical of apoptotic nuclei. This provides evidence that, during Drosophila oogenesis, the nurse cells undergo apoptosis. Apoptotic nuclei have also been detected in dumping-defective egg chambers, indicating that the cytoplasmic depletion of nurse cells is concurrent with but apparently not the cause of the process.
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  • 92
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    Development genes and evolution 183 (1977), S. 249-268 
    ISSN: 1432-041X
    Keywords: Pattern-formation ; Embryogenesis ; Maternal-effect mutants ; Drosophila melanogaster
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The mutationbicaudal (Bull, 1966) causes embryos to develop a longitudinal mirror image duplication of the posteriormost abdominal segments, while head and thorax are missing. These embryos occur with varying frequencies among eggs laid by mutant females, irrespective of the paternal genotype. Recombination and deletion mapping indicate thatbicaudal (bic) is a recessive, hypomorphic, maternal-effect mutation mapping at a single locus on the second chromosome ofDrosophila melanogaster close tovg (67.0±0.1). The frequency of bicaudal embryos depends on the age of the mother, her genetic constitution and the temperature at which she is raised. Best producers are very young females hemizygous forbic (bic/Df(2)vg B ) at 28° C. Under these conditions 80% to 90% of the eggs which differentiate can show the bicaudal embryo phenotype. Upon ageing of the mother the frequency of bicaudal embryos declines rapidly, and most of the eggs develop the normal body pattern. Temperature shift experiments suggest a temperature-sensitive period at the onset of vitellogenesis. The mutation causes several types of abnormalities in the segment pattern of theDrosophila embryo, which are interpreted as various degrees of expression of the mutant character. The most frequent abnormal phenotype is the symmetrical bicaudal embryo with one to five abdominal segments duplicated. Less frequent are asymmetrical types, in which the smaller number of segments is always in the anterior reversed part. Other phenotypes are embryos with missing or rudimentary heads, and embryos with irregular gaps in the segment pattern. In bicaudal embryos, the pole cells, formed at the posterior pole of the egg prior to blastoderm formation, are not duplicated at the anterior. The significance of thebicaudal phenotypes for embryonic pattern-formation inDrosophila is discussed.
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    Development genes and evolution 183 (1977), S. 233-248 
    ISSN: 1432-041X
    Keywords: Cytoplasmic architecture ; Ultrastructure ; Insect egg ; Pattern formation ; Yolk ; Cytoplasma-Architektur ; Ultrastruktur ; Insekten-Ei ; Musterbildung ; Dotter
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Description / Table of Contents: Zusammenfassung 1. Das Ei der ZuckmückeSmittia spec. wurde licht- und elektronenmikroskopisch untersucht. Die vorliegende Arbeit beschreibt den Bau des Periplasmas und des Dotter-Endoplasma-Systems vor Bildung der Polzellen. 2. Das Periplasma, nach außen vom Oolemm und einer mehrschichtigen Eihülle begrenzt, besteht aus einer ribosomenreichen cytoplasmatischen Matrix, in die vor allem Mitochondrien und ER-Zisternen, wenig annulate lamellae und gelegentlich Golgi-Apparate eingelagert sind. Mikrotubuli wurden nur selten nachgewiesen. Öfters sind Anhäufungen einer dichten granulierten Substanz zu beobachten, die in ihrer Struktur dem Oosom-Material ähnelt. 3. Das Dotter-Endoplasma-System stellt ein Netzwerk aus Cytoplasma dar, in das Proteid-Dotterkugeln, Lipidtröpfchen sowie Glycogen-Anhäufungen eingelagert sind. Das Endoplasma, das sich zu 3–7 Plasma-Inseln erweitern kann und unmittelbar in das Periplasma übergeht, besteht wie dieses aus einer cytoplasmatischen Matrix und enthält die gleichen Zellelemente wie das Periplasma. Rosettenförmige Membran-Strukturen werden als “nuclear envelope organizing center” gedeutet. 4. Drei der sorgfältig analysierten Eier enthielten je 2 Kerne; sie lagen in Plasma-Inseln in der hinteren Eihälfte. 5. Sowohl im Periplasma wie im Dotter-Endoplasma-System sind alle Zellelemente unregelmäßig verteilt. Eine besondere Anordnung oder Zonierung ist nicht zu erkennen. 6. Die räumliche Verteilung der erfaßten Eikomponenten liefert keine Hinweise auf eine Funktion dieser Komponenten als Determinanten für die embryonale Musterbildung.
    Notes: Summary 1. Eggs of the midgeSmittia were investigated by light microscopy and transmission electron microscopy. This paper describes elements and architecture of periplasm and yolk endoplasm before the formation of pole cells. 2. The periplasm is coated externally by the oolemma and a multilayered egg shell. The periplasm consists of a cytoplasmic matrix rich in ribosomes; it contains mitochondria and ER cisternae, some annulate lamellae and an occasional Golgi complex. Microtubuli were demonstrated only rarely. Accumulations of a dense granulated substance resembling in its structure the oosome material were frequently observed. 3. The yolk endoplasm is a cytoplasmic network embodying proteid yolk particles, lipid droplets and accumulations of glycogen. The endoplasm is continuous with the periplasm and shows the same cell constituents. It may form between 3 and 7 cytoplasmic islands free of yolk particles. Rosette-shaped membranous structures in the yolk endoplasm are interpreted as nuclear envelope organizing centres. 4. Three carefully analysed eggs contained 2 nuclei each. both nuclei were situated in the posterior egg half. 5. Periplasm and yolk endoplasm are characterized by random distribution of cell elements. No zonation or special accumulations could be recognized. 6. The spatial distribution of the egg components studied did not indicate that any of these components could function as a determinant in embryonic pattern formation.
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    Development genes and evolution 181 (1977), S. 333-355 
    ISSN: 1432-041X
    Keywords: Barnacle eggs ; Constriction rings ; Microfilaments ; Ultrastructure ; Peristalsis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary 1. The egg ofPollicipes polymerus, the common intertidal gooseneck barnacle, has been studied by electron microscopy. Constriction rings, similar to the contractile rings of cleaving cells and polar lobes, move unidirectionally from the animal to the vegetal pole of newly fertilized eggs. This is referred to as peristaltic constriction. The present paper describes the fine structure of the egg during first polar body formation and peristalsis. 2. During formation of the polar body, dense bodies are produced by the Golgi and extracellular plaques are observed. Thin microfilaments (40–60 Å) are in the egg adjacent to the polar body. 3. In eggs undergoing peristalsis, the appearance of extracellular spheres, flocculent material and filaments is observed. Intracellularly large numbers of multivesiculate bodies, glycogen granules, mitochondria and protein-carbohydrate and lipid yolk bodies are seen at the level of constriction. 4. Thin microfilaments are found in the cortical area of newly-fertilized eggs exclusively in peristaltic constriction rings. Filaments are oriented primarily in a meshwork, although circumferentially-oriented filaments are also found in rings near the vegetal pole. Microvilli extend into the space created between a constriction and the elevated egg membrane. 5. A model is proposed to explain the peristalsis in this species. It is suggested that information from a pacemaker region activates peristalsis by affecting filament polymerization and orientation. One function of peristalsis may be elongation of the egg from a sphere to an ovoid, although other possibilities such as elevation of the egg membrane, segregation of the lipid yolk to the vegetal pole and predetermination of the first cleavage plane are also discussed.
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    Development genes and evolution 192 (1983), S. 103-107 
    ISSN: 1432-041X
    Keywords: Cell Surface ; Drosophila melanogaster ; 20-hydroxyecdysone ; protein changes ; Two-dimensional polyacrylamide gel electrophoresis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Drosophila cell lines have provided popular material for study of the mechanisms by which steroid hormones regulate cellular events. Previous investigations at the organismic or organ level have suggested that ecdysteroids are bound by a cytoplasmic receptor, and that the resulting complex translocates to the nucleus where it results in active transcription of a few genes. The protein products of these primary responding genes then modulate a larger series of secondary transcriptional changes. In cultured cells, other investigators have detected the hormonally-induced synthesis of only 4–5 new polypeptides through 72 h of treatment. Although these proteins may represent the gene products associated with the primary response, this small number of changes is surprising in view of the rapid morphological alteration of the cells and changes in such surface-mediated behavior as substrate adhesion and agglutinability observed within the same time interval. In this report, we show that lactoperoxidase-catalyzed radioiodination followed by 2-dimensional polyacrylamide gel electrophoresis and autoradiography provide an effective protocol for visualizing cell surface proteins of a Drosophila cell line. Among the more than 175 labeled species detected, comparisons of control cells with those treated by 20-hydroxyecdysone for 72 h shows at least 27 differences. We interpret these differences as the result of the secondary transcriptional response to the hormone.
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    Development genes and evolution 191 (1982), S. 331-334 
    ISSN: 1432-041X
    Keywords: Genetic mosaics ; Cell autonomy ; Cell affinities ; Drosophila melanogaster
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary InDrosophila melanogaster, segmental specification takes place in groups of cells around the blastoderm stage. This segmental specification requires the function of the genes of the bithorax-complex. We have studied preblastoderm mosaics (gynandromorphs) of mutant (bx 3,pbx, Ubx, Ubx 80) and wildtype (heterozygotes for these alleles) cells. The results show a total cell autonomy in the differentiation of both wildtype and homoeotially transformed cells. However, several unexpected phenotypes were found. They are discussed in terms of the function of the bithorax genes and early interactions between mutant and wildtype territories.
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    Development genes and evolution 186 (1979), S. 65-70 
    ISSN: 1432-041X
    Keywords: Sea urchin ; Embryo ; Collagen ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Collagen fibrils with a main period banding of 610 Å and 220 Å in width were observed in the blastocoel of 72-h embryos of the sea urchin,Strongylocentrotus purpuratus. Non-striated fibrils of 50 Å diameter were also observed. The collagen is seen in highest concentration in the vicinity of mesenchyme cells which are richly endowed with endoplasmic reticulum and secretory vesicles. A role for collagen in cell attachment, orientation and spicule formation is discussed.
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    Development genes and evolution 192 (1983), S. 171-178 
    ISSN: 1432-041X
    Keywords: Differentiation ; Digestive tract ; Endoderm ; Organ culture ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The self-differentiation potency of the endoderm of the chick embryo was investigated mainly by transmission electron microscopy. Endodermal fragments isolated from 4- to 6-day stomach or small intestine were cultured in the absence of mesenchyme and were able to differentiate in vitro into organ-specific epithelia. Endodermal fragments isolated from the stomach region differentiated into a pseudo-stratified epithelium with periodic acid Schiff-positive mucous granules in the apical cytoplasm, while those from the small intestinal region differentiated into a simple columnar epithelium with a striated border which was positive in alkaline phosphatase activity. These features are comparable with those of the mucous secretory epithelium of the normal embryonic stomach and the absorptive epithelium of normal embryonic small intestine, respectively. Next, the self-differentiation potencies were investigated of the upper and lower layers of the blastoderms, at stages 1–5 of Hamburger and Hamilton (H. and H.). Both stomach-type and small-intestine-type epithelia developed only when fragments of the lower layer isolated from the blastoderms older than stage 3 of H. and H. were cultured, suggesting that cells possessing the potency to differentiate into the stomach- and small-intestine-type epithelia exist in the definitive endoderm at the beginning of its formation.
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    Development genes and evolution 188 (1980), S. 65-73 
    ISSN: 1432-041X
    Keywords: Nuclear migration ; Cleavage ; Microtubules ; Ultrastructure ; Gall midge
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary In the eggs ofWachtliella persicariae the cleavage nuclei move relative to the surrounding ooplasm. This ‘active’ migration is caused by an organelle whose ultrastructure was studied throughout the mitotic cycle. It consists of a greatly enlarged polar cytaster derived from the mitotic apparatus, linked to the nucleus by 100 Å filaments. The microtubules of the cytaster were found only during periods of active nuclear migration, i.e., from the onset of anaphase to the early prophase of the next mitotic cycle. They are always solitary and follow the course of the astral rays, which are known to temporarily adhere to peripheral structures of the egg cell and to exert tractive forces. In contrast to the cytaster microtubules, the microtubules in the spindle are bundled and persist from early metaphase through late telophase. During ontogenesis the first migration cytaster is built up between 3 and 12 min after oviposition near the anterior egg pole, in the vicinity of the sperm nucleus. In non-inseminated eggs time lapse films show a migration cytaster to develop autonomously in a region free from nuclei, but it does not follow the normal path of the male pronucleus. In several cases the female pronucleus, which remains without a cytaster of its own, was observed to move to the cytaster generated in the absence of the male pronucleus. Whether or not it is adhering to a nucleus, the cytaster divides into two at the correct time, i.e, corresponding to the first cleavage division in fertilized eggs. In some non-inseminated eggs this type of ‘pseudocleavage’ has been observed to occur repeatedly, giving rise to an increasing number of anucleate cytasters.
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  • 100
    ISSN: 1432-041X
    Keywords: Salivary gland ; Protein synthesis ; Larval development ; Drosophila melanogaster
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Patterns of protein synthesis in the salivary glands ofDrosophila melanogaster have been studied throughout late larval and prepupal development by pulse labelling the tissues with35S-methionine. Specific changes to the pattern of proteins synthesized during development are found and the significance of these changes is discussed in view of the known changes in gene (puffing) activity which occur at the same times. We review the problem of salivary gland function in “prepupal”Drosophila.
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