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  • Drosophila  (65)
  • rotifers  (61)
  • Springer  (126)
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  • 2005-2009
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  • 1980-1984  (80)
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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Journal of molecular evolution 35 (1992), S. 51-59 
    ISSN: 1432-1432
    Keywords: Drosophila ; Gart locus ; Chironomus tentans ; Purine nucleotide biosynthesis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The Drosophila Gart locus consists of two genes. One gene encodes three enzymes in the de novo purine nucleotide biosynthesis pathway [glycinamide ribonucleotide synthetase (GARS), aminoimidazole ribonucleotide synthetase (AIRS), and glycinamide ribonucleotide transformylase (GART)]. The second gene lies within an intron of the purine gene and encodes a cuticle protein. To investigate the evolution of the Gart locus, the Chironomus tentans homolog was cloned by screening a genomic DNA library with a polymerase chain reaction product. This study shows that the interesting structural features of this locus conserved in two distant Drosophila species are not found in the Chironomus homolog. These features include the cuticle protein gene nested within an intron and the existence of an alternative transcript to yield a monofunctional enzyme. In addition, the extremely rapid divergence of coding sequence seen for members of the tandemly duplicated AIRS domain in Drosophila is found to be much less rapid in Chironomus.
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  • 2
    ISSN: 1432-1432
    Keywords: Drosophila ; per gene ; Threonine-Glycine ; repeat sequence ; melanogaster subgroup phylogeny
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The Threonine-Glycine (Thr-Gly) region of the period gene (per) in Drosophila was compared in the eight species of the D. melanogaster subgroup. This region can be divided into a diverged variable-length segment which is flanked by more conserved sequences. The number of amino acids encoded in the variable-length region ranges from 40 in D. teissieri to 69 in D. mauritiana. This is similar to the range found within natural populations of D. melanogaster. It was possible to derive a Thr-Gly “allele” of one species from that of another by invoking hypothetical Thr-Gly intermediates. A phylogeny based on the more conserved flanking sequences was produced. The results highlighted some of the problems which are encountered when highly polymorphic genes are used to infer phylogenies of closely related species.
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  • 3
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    Journal of molecular evolution 34 (1992), S. 130-140 
    ISSN: 1432-1432
    Keywords: Drosophila ; Sophophora ; cDNA-DNA hybridization ; Phylogenetics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary We have performed DNA-DNA hybridization experiments among several species of Drosophila using the evolutionarily conserved portion of the genome representing sequences coding for amino acids of proteins. This was done by using as tracer, radioactively labeled complementary DNA that was reverse transcribed from adult mRNA. We show that this procedure extends phylogenetically the distance over which the technique can be applied to fast-evolving groups such as Drosophila. The major phylogenetic conclusions are (1) the subgenus Sophophora is a monophyletic lineage; (2) within Sophophora the melanogaster subgroup is closer to the obscura group than either group is to the willistoni group; (3) the subgenus Drosophila is complex with most major lineages originating deep in the phylogeny; the subgenus may not be monophyletic; (4) as with most groups classically placed in Drosophila, the Hawaiian Drosophila originate early, supporting the notion that this lineage is older than the extant islands; and (5) the virilis/repleta lineage is monophyletic within Drosophila.
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  • 4
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    Development genes and evolution 192 (1983), S. 164-170 
    ISSN: 1432-041X
    Keywords: Drosophila ; Imaginal disc ; Morphogenesis ; Tissue culture
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The early morphogenesis of the eye-antennal disc ofDrosophila in response to 20-hydroxy ecdysone involves the curling of the eye anlagen dorsally over the antenna. During this process, the area of the peripodial membrane is substantially reduced. The peripodial membrane is taut at this stage, and if it is cut the curling of the disc cannot continue, and the eye anlagen returns to its original position within one minute of the operation. In contrast, cutting the columnar epithelium between the eye and antennal anlagen does not disrupt curling, but actually facilitates it. During curling, the cells of the peripodial membrane appear healthy, and exhibit basal extensions. We suggest that the curling of the eye is mediated by the conversion of cuboidal peripodial membrane cells into pseudostratified columnar epithelium at the edges of the peripodial membrane. Subsequently, cells of the peripodial membrane secrete first a pupal cuticle, and then an imaginal cuticle.
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  • 5
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    Development genes and evolution 192 (1983), S. 275-279 
    ISSN: 1432-041X
    Keywords: Evagination ; Morphogenesis ; Metamorphosis ; Female genital disc ; Drosophila
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The morphology of the evaginating female genital disc ofDrosophila melanogaster was examined at different stages of metamorphosis. The observations show that the internal genital organs are derived from the anterior half of the disc and that their morphogenesis is mainly a protrusion of the different primordial areas of the disc epithelium. The external genital and anal derivatives originate from the posterior half of the disc, which undergoes complex rearrangements during metamorphosis. The disc opens along the posterior margin and the dorsal and ventral epithelia evert and thereby completely reverse their anteroposterior orientation. Dramatic elongation has been observed during the formation of the seminal receptacle. The cells of the repressed male genital primordium do not form any recognizable structures and are assumed to be eliminated during metamorphosis.
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  • 6
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    Development genes and evolution 192 (1983), S. 299-302 
    ISSN: 1432-041X
    Keywords: Differentiation ; Teratogens ; Drosophila ; 5-Azacytidine ; Methylation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The effects of cytidine and cytidine analogs were studied inDrosophila embryonic cell cultures and two wild-type established cell lines, Oregon-R and Schneider line 2. Primary embryonic cultures have been shown to be an excellent system for the study of embryonic development; a number of cell types undergo normal differentiation in vitro. Treatment of these cultures with putative teratogens resulted in an inhibition of muscle and/or neuron differentiation in our study. Treatment of these cells with cytidine and seven other analogs had no effect on neuron and muscle differentiation. The compound 5-azacytidine, when added to primary cell cultures, inhibited normal differentiation at subtoxic doses while inducing the production of three proteins that comigrate with the heat-shock proteins, hsp 23, 22a and 22b. 5-Azacytidine did not stimulate differentiation in Oregon-R or SchneiderDrosophila cell lines. The in vitro blockage of differentiation by 5-azacytidine suggests that it may act as a teratogen.
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  • 7
    ISSN: 1420-9071
    Keywords: Aromatic plants ; essential oils ; Drosophila ; insecticides
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract Effects of the essential oils (EOs) extracted from eleven aromatic plants belonging to the Lamiaceae family (common in the Greek flora) were examined upon three different developmental stages ofDrosophila auraria. All of the EOs examined exhibited insecticidal effects, either by preventing egg hatching, or by causing the death of larvae and adult flies. In several cases, malformation and/or prohibition of puparium formation was also observed.
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  • 8
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    Development genes and evolution 192 (1983), S. 280-284 
    ISSN: 1432-041X
    Keywords: Evagination ; Morphogenesis ; Metamorphosis ; Intersexual genital disc ; Drosophila
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Morphogenetic movements of the intersexual genital disc of thedoublesex-dominant mutant ofDrosophila melanogaster were followed during metamorphosis. Intersexual genital discs contain well developed genital primordia of both sexes as well as an anal primordium, and all of these primordia evaginate simultaneously. The female genital primordium is deflected to the ventral side by the male genital primordium which is located anterior to it. Subsequently the anterior parts of the two genital primordia project their internal appendages in parallel in the anterior direction. The morphogenetic movements closely resemble those of the corresponding parts of normal males and females. The disc opens at the stalk along the posterior edge and the two genital primordia completely evert their posterior parts. These areas undergo complex rearrangements whereby the anlage for the male genital arch as well as that for the 8th tergite evert and move around the lateral side of the disc. They both fuse dorsally after enclosing the anal tube. The formation of the characteristic abnormalities of the intersexual genitalia seems not to result simply from spatial problems of the simultaneous evagination of the genital anlagen but rather to be a direct result of the ambiguous genetic signalling in the intersexual cells of these primordia.
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  • 9
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    Development genes and evolution 192 (1983), S. 337-346 
    ISSN: 1432-041X
    Keywords: Drosophila ; Gynandromorphs ; Genital disc ; Compartments ; Evolution
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The genital imaginal disc ofDrosophila differentiates the terminalia, i.e. the genitalia and analia, of both sexes. It represents a composite anlage, containing a female genital primordium, a male genital primordium and an anal primordium. In normal males and females, only one of the two genital primordia differentiates; the other is developmentally repressed. Therefore, cell-lineage relationships between the male and female genital primordia can only be studied in sexual mosaics which differentiate female and male cells. We producedMinute (M)‖non-Minute(M+) gynandromorphs and selected those with sexually mosaic terminalia for a cell-lineage analysis. In these mosaics, either the male (XO) or female (XX) cells wereM + and thus had a growth advantage. The differential growth rates served as a tool to detect clonal restrictions. In control gynandromorphs (M +‖M +), the amount of female genitalia differentiated was largely independent of the amount of male genitalia present. In contrast, male and female anal structures, as a rule, added up to one full set. The same was true for the experimentalM‖M + gynandromorphs, but the contribution ofXX andXO cells to mosaic terminalia changed drastically due toM + cells competing successfully against the more slowly growingM cells. Specific subsamples ofM‖M + gynandromorphs showed thatM cells in a non-mosaic primordium are shielded from cell competition taking place in the neighbouring mosaic primordium. We conclude that the three primordia of the genital disc represent developmental compartments. In the genital primordia, even developmentally repressedM + cells compete successfully against developmentally activeM cells.
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  • 10
    ISSN: 1432-041X
    Keywords: Muscle ; Salivary glands ; Gut ; Programmed cell death ; Steroid hormones ; Drosophila
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary In holometabolous insects, the steroid molting hormone 20-OH-ecdysone (ecdysterone) orchestrates the diverse developmental events of metamorphosis, in large part by regulating gene expression. In Drosophila, the Broad Complex (BR-C) is one of the first loci to be induced by ecdysterone at the end of larval life, and is essential for translating the hormonal signal into the behavioral and anatomical events which herald the onset of metamorphosis. BR-C products are believed to act by binding to and modifying the transcriptional activities of other hormone-sensitive genes. In addition to abnormalities of the epidermis, BR-C mutants dying during metamorphosis manifest a syndrome of multiple internal tissue defects which represent a failure of the larval-to-adult transition. We have reported features of central nervous system metamorphosis requiring BR-C function, notably morphogenetic movements and optic lobe organization. In this paper we describe defective development of salivary glands, flight muscles, and gut in BR-C mutants, including: persistence of larval salivary glands; failure of the adult salivary glands to extend into the thorax; abnormalities of midgut transition and of proventriculus structure and location; and absence of dorsal-ventral indirect flight muscles. Some of these abnormalities represent defects in programmed cell death. Distinct patterns of phenotypes were seen in mutants of each of the three lethal complementation groups comprising the BR-C. The patterns of phenotypes suggest overlapping but distinct functions encoded by this complex locus.
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  • 11
    ISSN: 1432-041X
    Keywords: Drosophila ; Imaginal discs ; Pattern formation ; rotund
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary InDrosophila imaginal discs, pattern formation requires the activity of three positional information systems, antero-posterior (A/P), dorso-ventral (D/V) and proximo-distal (P/D). Three genes,Decapentaplegic, Distal-less androtund (rn), involved in pattern formation along the P/D axis have been characterized. Thern gene is required in a sub-distal region, localized at a similar position along the P/D axis in all appendages; it encodes two major transcripts, m1.7 and m5.3, both expressed in the central region of all the major imaginal discs. The present study of these transcripts in severalrn mutant favours m5.3 as encodingrn morphogenetic function in the imaginal discs. The fine characterization of its distribution partitions all major imaginal discs in domains along the P/D axis. The ventral and dorsal discs appear to be similarly but not identically organized: two P/D domains are evident in the wing and haltere discs whilst the leg and antenna discs appear to be composed of at least three. We also show that m5.3 is sex-regulated in the genital disc and thatrn function is required for proper development of a sub-distal structure of the female genitalia. This suggests that the primordia of the female genitalia may be organized in a similar way to the other imaginal discs, and strongly supports the hypothesis thatrn function is specific to pattern formation along the P/D axis and that it may be involved in the establishment or maintenance of this pattern.
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  • 12
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    Development genes and evolution 201 (1992), S. 364-375 
    ISSN: 1432-041X
    Keywords: Drosophila ; Tissue culture ; In vitro ; Invertebrate embryogenesis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary We have devised techniques to culture whole, dissected embryos of Drosophila melanogaster. We examine multiple aspects of the morphological and physiological development of the epidermis, musculature, nervous system, and internal organs in this cultured preparation, and show that in vitro development closely parallels normal embryogenesis. These techniques permit a wide range of experimental manipulations during embryogenesis and allow us to extend observations through late embryonic stages, after cuticle deposition. Applications of this technique are presented.
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  • 13
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    Development genes and evolution 192 (1983), S. 48-50 
    ISSN: 1432-041X
    Keywords: Drosophila ; Hybrid lethality ; Imaginal discs ; Interspecific transplantation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Females ofDrosophila melanogaster, crossed with males ofDrosophila mauritiana, produce only female offspring. The male hybrid larvae grow very slowly, fail to pupate and die after prolonged larval life. Imaginal discs from these male hybrids transplanted into Drosophila melanogaster larvae can give rise to adult structures with normal patterns. Differentiation of hybrid imaginal disc tissue is improved by short term culture in non-hybrid larvae prior to metamorphosis, suggesting that the hybrid larval haemolymph is inadequate to sustain normal imaginal disc growth. This may represent the physiological basis of the reproductive isolating mechanism separating the twoDrosophila species
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  • 14
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    Development genes and evolution 192 (1983), S. 270-274 
    ISSN: 1432-041X
    Keywords: Fate map ; Repressed primordium ; Sex determination ; Genital disc ; Drosophila
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The female genital disc ofDrosophila melanogaster was cut into distinct fragments, and the prospective fates of the fragments were determined by putting them through metamorphosis in host larvae. The dorsal epithelium contains the anlagen for the anal plates and parovaria, as well as the repressed male genital primordium. The ventral epithelium gives rise to all of the female genital structures except for the parovaria. The results were compared with published fate maps and observations made in experiments with sex-transforming mutations. This allowed us to establish a detailed three-dimensional fate map of the female genital disc, which shows a well-developed female genital primordium in the ventral epithelium, a repressed male genital primordium in the anterior part of the dorsal epithelium and an anal primordium in the posterior region of the dorsal disc epithelium.
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  • 15
    ISSN: 1432-041X
    Keywords: Drosophila ; Cell degeneration ; Imaginal disc ; Basal lamina ; Blood cells
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The mutationsvestigial (vg; recessive) andUltravestigial (vg U; dominant) ofDrosophila melanogaster give rise to identical mutant adult phenotypes in which much of the cases this results from cell death in the presumptive wing margin of the wing disc in the third larval instar, but the process of cell degeneration is quite different in the two mutants. Invg cell death occurs continuously throughout the third larval instar, while invg U it occurs only in the early third instar. Cells fragment and some of the fragments condense, becoming electron dense (“apoptosis”). Both condensed and ultrastructurally normal cell fragments are extruded to the basal side of thevg disc epithelium. They accumulate under the basal lamina in the wing pouch area until they are phagocytosed by blood cells entering the wing pouch during the six hours following pupariation. Fragments are not extruded from thevg U epithelium but are apparently phagocytosed by neighboring epithelial cells. The basal lamina undergoes mophological changes following pupariation and is phagocytosed by blood cells in both wild-type andvestigial, but investigial the degenerated cell fragments are also engulfed by the same blood cells.
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  • 16
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    Development genes and evolution 192 (1983), S. 317-326 
    ISSN: 1432-041X
    Keywords: Neurogenic mutations ; Topological specificity ; Drosophila
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Neurogenic mutations have been found to cause the neuralization of certain regions of the ectoderm and yet to permit normal development of the remaining embryonic cells. Thus, it seems that the activity of the wild-type alleles of these genes is dispensable in a considerable fraction of the embryo during wild-type development. This effect might be a consequence of the cells' position within the embryo; alternatively, it might be independent of the position but be due rather to the genetic activity experienced by the cells previous to their commitment. The results described in this paper indicate that genes controlling patterning along the embryonic dorso-ventral perimeter (dorsal and Toll) are epistatic to genes controlling neurogenesis, their activity deciding which ectodermal cells are susceptible to neurogenesis. Using alleles with low expressivity, evidence was obtained showing that the tracheal placodes define the boundary of the territory which has neurogenic abilities at thoracic and abdominal levels.
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  • 17
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    Development genes and evolution 201 (1992), S. 105-112 
    ISSN: 1432-041X
    Keywords: Drosophila ; Genital disc ; tra-2 ts ; Differentiation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Diplo-X flies homozygous for the transform-er-2 ts (tra-2 ts) mutation develop into females at 16° C, while they develop into males at 29° C (Belote and Baker 1982). By means of this conditional mutation, we have carried out a detailed analysis of the development of the genital disc. Temperature shifts between 16 and 29° C, in both directions, and temperature pulses at 29° C, have been applied during the larval growth of tra-2 ts homozygous diplo-X flies, and the external derivatives of the genital disc have been analysed. Genital discs shifted from 16 to 29° C rapidly lose their capacity to differentiate female genital structures, while they become able to differentiate male genital structures whose inventory is more complete the earlier in larval development the temperature shift is carried out; moreover, duplicated male genital structures were observed. In the shift from 29 to 16° C, the genital disc loses its capacity to differentiate male genital structures, while it becomes able to differentiate female genital structures. The inventory of male structures is smaller, and the inventory of the female structures is more complete, the earlier in larval development the temperature is shifted. No duplicated female or male genital structures were observed in the downshift experiment. With respect to the analia, the shift from 16 to 29° C resulted in the quick formation of pure male anal plates, while in the opposite shift the formation of pure female anal plates occurred gradually. Moreover, the time course for the dorsal and ventral anal plates to show normal female phenotype was different: when the dorsal anal plates were completely normal, it was still possible to find incomplete ventral anal plates. In the pulse experiment at 29° C, the genital disc is able to differentiate both female and male genital structures, although the inventory of the latter ones was not complete. In addition, the capacity of the genital disc to differentiate male genital structures depended on the duration of the temperature pulse. The anal plates were always female, although they showed a reduction in their size, the ventral female anal plate being more affected than the dorsal one. No male anal plates were observed. The results have revealed that the genital disc follows a sequence in its capacity to differentiate female or male adult structures. We suggest that this sequence reflects the sequence of determination events occurring in the genital disc during its larval growth. In addition, results shown here provide evidence for the existence in the female genital primordium of a set of cells capable of giving rise either to female genital structures (ventral vaginal plates) or to male genital structures (hypandrium and penis apparatus). We also present evidence supporting the previous idea of two primordia for the anal plates.
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  • 18
    ISSN: 1432-041X
    Keywords: Drosophila ; Homeotic gene regulation ; Antennapedia ; Development ; β-galactosidase
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary In order to study the regulation of spatial and temporal expression of the homeotic gene Antennapedia (Antp) in Drosophila melanogaster, we have constructed fusion genes which contain Antp sequences linked to the reporter gene lac Z of Escherichia coli. In one case of P-element transformation, a fusion gene construct integrated into the endogenous Antp gene close to one of the two promoters (P1). The spatial expression from the reporter gene in this transformant line, as analysed by the detection of β-galactosidase activity, was found to exactly mimic the normal expression from the P1 promoter of the Antp gene. We have used this unique transformant as a tool for studying the expression of the P1 promoter in embryonic, larval and adult development. Parallel lines transformed with the same fusion gene construct did not confer a correct P1 pattern of expression. The position in the genome was, therefore, crucial for the expression pattern of the reporter gene. Experiments aiming at the detection of autoregulatory control of Antp gene expression were designed. The results did not, however, support models of positive or negative autoregulation of P1 expression by Amp protein.
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  • 19
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    Development genes and evolution 201 (1992), S. 120-123 
    ISSN: 1432-041X
    Keywords: Integrin ; Drosophila ; In vitro ; Imaginal disc
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Drosophila imaginal disc cell lines show a characteristic pattern of aggregation in culture, which appears to be due to cell-cell rather than cell-substrate interactions. We have examined the distribution of PS integrins in wing and leg cell lines, and find that these integrin homologues are expressed preferentially in aggregates. Cell sheets, small cell clumps and chains of cells express antigen at points of cell-cell contact only.
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  • 20
    ISSN: 1432-041X
    Keywords: Drosophila ; Pattern formation ; Segment polarity genes ; gooseberry ; Cell interactions
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Segment polarity genes define the cell states that are required for proper organization of each metameric unit of the Drosophila embryo. Among these, the gooseberry locus has been shown to be composed of two closely related genes which are expressed in an overlapping single-segment periodicity. We have used specific antibodies raised against the protein product of the gooseberry proximal (gsb-p) gene to determine the spatial distribution of this antigen in wild type embryos, and to monitor the effects of segment polarity mutants on the pattern of the gsb-p protein distribution. We find that the gsb-p protein accumulates beneath each posterior axonal commissure in the progeny of neuroblasts deriving from the epidermal compartments of wingless (wg) and engrailed (en) expression. The results of this analysis support the idea that gsb-p has a specific role in the control of cell fates during neurogenesis, and indicate that en and wg provide critical positional cues to define the domain in which gsbp will be activated. Furthermore, these data suggest that, in order to be expressed in the embryonic CNS, gsb-p may preliminarily require activity of the gooseberry-distal gene in the epidermis.
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  • 21
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    Development genes and evolution 201 (1992), S. 88-94 
    ISSN: 1432-041X
    Keywords: Fate map ; Drosophila ; Flight muscle ; Mosaics ; Cell lineage
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary A blastoderm fate map has been prepared for Drosophila, using mosaics of a temperature-sensitive mutation, shibire (shi). The mutation can cause abnormal flight muscle morphology, inducible only by a short heat pulse in early metamorphosis. Thus muscle lineage and development are unperturbed until the heat pulse in the early pupa. The developmental focus of the shi muscle phenotype maps to the ventral thorax at the expected site of thoracic mesoderm, and probably indicates the blastoderm progenitors of the adult flight muscle. The fate map provides greater detail than previously available for the dorsolongitudinal fibers (DLM) of flight muscle, showing wide separation of the fibers of flight muscle. DLM fibers a and b map close together, and far anterior to fibers e and f, which also map together. On a fate map, common developmental focus indicates a common blastoderm origin. Thus, the observed pattern for DLM fibers suggests that the blastoderm progenitors for each of these syncytial fiber pairs (a, b; e, f) include only one or two cells. It follows that there is usually a single genotype within each fiber pair (a, b; e, f), and that this genotype is directly reflected in the fiber phenotype. In a large number of cases, DLM fibers a and b differ in phenotype from other DLM fibers, in parallel with their other differences (e.g., timing of development in pupa, innervation, motor activity). The separation of fate map locations of the developmental focus for DLM fibers within mesoderm suggests that specific fibers of flight muscle may, in normal development, originate in all three thoracic mesodermal parasegments.
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  • 22
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    Development genes and evolution 202 (1992), S. 23-35 
    ISSN: 1432-041X
    Keywords: Ecdysteroid ; Imaginal disc ; Drosophila ; Cell line
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary We have investigated the action of the moulting hormone 20-hydroxy ecdysone (20-HOE) on our leg and wing imaginal disc cell lines. At the morphological level, cells stop dividing and there is some cell death. The remaining cells elongate and aggregate, often producing long processes which form connections between different aggregates. 20-HOE acts within the first one or two days of a passage, at an optimum concentration of 10 ng/ml, this being about 1/100 of the optimum for ecdysone. One cloned wing cell line, C9, has been found to be relatively insensitive to the action of 20-HOE. We have been able to select for resistance to 20-HOE by growing cells in gradually increasing concentrations of hormone followed by passages in hormone-free medium. This has enabled us to isolate a wing cell line C1.8R from its parent cloned line C1.8+. This shows no response to 20-HOE, and cell growth continues even at hormone concentrations as high as 150 ng/ml. We have measured chitin synthesis by the incorporation of radioactive glucosamine into a cell fraction resistant to extensive alkali hydrolysis. The residue was incubated with chitinase, which resulted in a 50% reduction in labelled product. Treatment with 10 ng/ml of 20-HOE dramatically increased chitin synthesis in line C1.8+, but had no effect in the line C1.8R, selected for resistance to hormone.
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  • 23
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    Development genes and evolution 202 (1992), S. 49-60 
    ISSN: 1432-041X
    Keywords: Drosophila ; Delta ; Enhancers ; Suppressors ; Neurogenesis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary We have screened for dominant enhancers and suppressors of the wing phenotype associated with two Delta alleles: Dl 9P39, an amorphic allele, and Dl FE32, an antimorphic allele. The interactions of some of the modifiers with Delta are due to haplo-insufficient expression of the corresponding genes. Although not explicitly shown for the remaining cases, we assume that haploin-sufficiency is also the basis for the relationships of these genes to Delta, since no allele specific interactions were observed. The modifiers found define 22 genes with pleiotropic expression, which can be classified into two groups: genes required for wing vein pattern formation and for neurogenesis, and genes which are not required for neurogenesis. Among the genes of the first group, Hairless and Star were previously known to participate in neural development. One further modifier was found which may correspond to a new neurogenic gene. The second group of genes is larger and includes already known loci, e.g., Plexate, blistered, plexus, etc, as well as other previously unidentified genes, which function during wing morphogenesis.
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  • 24
    ISSN: 1432-041X
    Keywords: Early neurogenesis ; Neurogenic mutants ; Drosophila
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The central nervous system (CNS) ofDrosophila develops from precursor cells called neuroblasts. Neuroblasts segregate in early embryogenesis from an apparantly undifferentiated ectoderm and move into the embryo, whereas most of the remaining ectodermal cells continue development as epidermal cell precursors. Segregation of neuroblasts occurs within a region called the neurogenic field. We are interested in understanding how the genome ofDrosophila controls the parcelling of the ectoderm into epidermal and neural territories. We describe here mutations belonging to seven complementation groups which effect an abnormal neurogenesis. The phenotypes produced by these mutations are similar. Essential features of these phenotypes are a conspicuous hypertrophy of the CNS accompanied by epidermal defects; the remaining organs and tissues of the mutants are apparently unaffected. The study of mutant phenotype development strongly suggests this phenotype to be due to misrouting into the neural pathway of development of ectodermal cells which in the wildtype would have given rise to epidermal cells, i.e. to an initial enlargement of the neurogenic region at the expense of the epidermogenic region. These observations indicate that the seven genetic loci revealed by the mutations described in this study contribute to control the neurogenic field. The present results suggest that in wildtype development neurogenic genes are supressed within all derivatives of the mesoderm and endoderm and some derivatives of the ectoderm, and conditionally expressed in the remaining ectoderm. The organisation of the neurogenic field in the wildtype is discussed.
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    Development genes and evolution 201 (1992), S. 1-11 
    ISSN: 1432-041X
    Keywords: Drosophila ; Neurogenesis ; Signals ; Delta ; Notch
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The ectodermal germ layer of Drosophila melanogaster gives rise to two major cell lineages, the neural and the epidermal. Progenitor cells for each of these lineages arise from groups of cells, whose elements must decide between taking on either fate. Commitment of the progenitor cells to one of the developmental fates implies two factors. One is intrinsic to the ectodermal cells and determines a propensity to take on neural fate; this factor is probably represented by the products of the so-called proneural genes, which are differentially distributed throughout the ectoderm. The other factor in the cells' decision to adopt one of the two alternative fates is intercellular communication, which is mediated by the products of the so-called neurogenic genes. Two types of interactions, one inhibiting and the other stimulating neural development, have been inferred. We discuss here the assumed role of various neurogenic genes, in particular Notch and Delta, in these processes.
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  • 26
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    Development genes and evolution 201 (1992), S. 194-220 
    ISSN: 1432-041X
    Keywords: Drosophila ; Enhancer trap lines ; Embryogenesis
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    Topics: Biology
    Notes: Summary Embryos of 171 Drosophila lines carrying a P-lacZ insertion on the second or third chromosome were analyzed regarding their pattern of lacZ expression. All lines were selected from a larger screen of about 4000 lines (Bier et al. 1989). Tissue specificity and time of onset of lacZ expression was documented for each line. Thereby, a comprehensive list of markers for the various tissue and cell types of the Drosophila embryo could be assembled. With the help of several P-lacZ lines the development of a number of structures was studied which so far had been described only insufficiently or not at all. In particular, the embryonic origin and early development of the oenocytes, imaginal discs, histoblasts, fat body, dorsal vessel, and perineurial cells was analyzed. Several previously unknown cell types associated with the dorsal vessel, trachea, and epidermis were discovered. By combining data regarding the origin of the different mesodermally derived organs it was possible to generate in some detail a fate map of the mesoderm of the stage 11 Drosophila embryo.
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    Cellular and molecular life sciences 48 (1992), S. 623-629 
    ISSN: 1420-9071
    Keywords: Drosophila ; heat shock ; stress ; heat shock protein ; gene regulation
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    Topics: Biology , Medicine
    Notes: Abstract Major alterations in genetic activity have been observed in every organism after exposure to abnormally high temperatures. This phenomenon, called the heat shock response, was discovered in the fruit flyDrosophila. Studies with this organism led to the discovery of the heat shock proteins, whose genes were among the first eukaryotic genes to be cloned. Several of the most important aspects of the regulation of the heat shock response and of the functions of the heat shock proteins have been unraveled inDrosophila.
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    Oecologia 92 (1992), S. 183-187 
    ISSN: 1432-1939
    Keywords: Drosophila ; Resource exploitation ; Decaying-herbage breeding ; Host choice
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    Topics: Biology
    Notes: Summary The Drosophila fauna of a deciduous flood plain forest rich in undergrowth near the river Isar, close to Munich, Germany, was surveyed in summer 1990. Decaying herbage baits (decay artificially induced) were set out to study the exploitation of that resource by Drosophila. Sixteen plant species belonging to several families dominant in the collecting area were tested. All attracted and produced drosophilid flies. Ten Drosophila species utilized decaying plant material as breeding sites; at least eight of the ten are polyphagous. Decaying stalks and leaves of Angelica sylvestris (Apiaceae) were examined in detail. In the case of the most frequent species of Drosophila attracted to A. sylvestris, the number of adults collected did not correlate with the number of flies emerging from the substrate. This was particularly true of D. limbata and D. phalerata. When oviposition and larval development of D. limbata and D. phalerata on A. sylvestris was tested in the laboratory, the number of offspring per female was the same in both species. The difference between these two species of the quinaria group in the exploitation of A. sylvestris in the field is therefore not due to differential suitability of the substrate.
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    Biochemical genetics 21 (1983), S. 199-211 
    ISSN: 1573-4927
    Keywords: Drosophila ; lactate dehydrogenase ; isozymic pattern ; development ; isozymic conversion
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    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract Partially purified lactate dehydrogenase (LDH) from third-instar larvae displays two bands (one major and one minor) on polyacrylamide gels. Analogous preparations from pupae and adults exhibit three LDH-staining bands (one major and two minor) in a similar pattern. The migration of the major band is similar for larvae, pupae, and adults, while the two minor LDH bands of pupae and adults migrate more slowly than the minor larval band. It has been shown that larval LDH incubated with β-nicotinamide adenine dinucleotide exhibits two additional minor bands with an electrophoretic mobility similar to that of the minor bands of both pupae and adults. The intensity of the minor larval LDH band (exhibited also by untreated preparations) is drastically reduced. This fact indicates that the life-cycle stage-dependent LDH isozymic distribution is possibly due to a posttranslational effect(s). Highly purified LDH from larvae, pupae, or adults, obtained by an affinity chromatography procedure, displays just one dispersed band, located in the area between the band 5 and the band 6 exhibited by crude extract preparations. These data, in combination with the lack of difference in catalytic properties among enzymes from larvae, pupae, and adults, suggest that LDH synthesis is controlled by the same single structural gene at all developmental stages.
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    Biochemical genetics 21 (1983), S. 199-211 
    ISSN: 1573-4927
    Keywords: Drosophila ; lactate dehydrogenase ; isozymic pattern ; development ; isozymic conversion
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    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract Partially purified lactate dehydrogenase (LDH) from third-instar larvae displays two bands (one major and one minor) on polyacrylamide gels. Analogous preparations from pupae and adults exhibit three LDH-staining bands (one major and two minor) in a similar pattern. The migration of the major band is similar for larvae, pupae, and adults, while the two minor LDH bands of pupae and adults migrate more slowly than the minor larval band. It has been shown that larval LDH incubated with β-nicotinamide adenine dinucleotide exhibits two additional minor bands with an electrophoretic mobility similar to that of the minor bands of both pupae and adults. The intensity of the minor larval LDH band (exhibited also by untreated preparations) is drastically reduced. This fact indicates that the life-cycle stage-dependent LDH isozymic distribution is possibly due to a posttranslational effect(s). Highly purified LDH from larvae, pupae, or adults, obtained by an affinity chromatography procedure, displays just one dispersed band, located in the area between the band 5 and the band 6 exhibited by crude extract preparations. These data, in combination with the lack of difference in catalytic properties among enzymes from larvae, pupae, and adults, suggest that LDH synthesis is controlled by the same single structural gene at all developmental stages.
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    ISSN: 1573-4927
    Keywords: Drosophila ; alcohol dehydrogenase ; enzyme polymorphisms, activity ratios
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    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract Representatives of five allozymic classes of Drosophila alcohol dehydrogenase have been compared with respect to their activity levels on two alcohol substrates, quantities of ADH protein, and stability in crude extracts. Within each allozymic class, strains from widely diverse geographic locations differ in their enzyme activity levels but are identical for a measure known as “activity ratio,” which is obtained by dividing the average activity reading on isopropanol by that obtained with ethanol. They are also similar in the rate at which ADH activity declines in crude extracts held at 25°C. For several of the fast-resistant and fast-moderate strains, differences in ADH activity are associated with differences in the amount of enzyme present. The catalytic efficiencies of the fast-resistant forms are considerably lower than those of the fast-moderate allozymes. The origin and persistence of the rare but ubiquitous fast-resistant allozyme is discussed.
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    Biochemical genetics 21 (1983), S. 703-711 
    ISSN: 1573-4927
    Keywords: Drosophila ; glucose-6-phosphate dehydrogenase ; polymorphism ; sequential electrophoresis
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    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract Studies were undertaken to investigate two critical aspects of the glucose-6-phosphate dehydrogenase polymorphism in Drosophila melanogaster. The first investigation unequivocally maps the genetic site of the G6PD locus to the X chromosome. The second study subjects a set of isochromosomal lines to sequential electrophoresis in an attempt to uncover common molecular heterogeneity within the global polymorphism, assuming that this variation may have gone undetected under conventional electrophoretic conditions. The genetic site was mapped following the segregation of the two common electrophoretic alleles, a so-called null allele, and two rare electrophoretic variants. From the pooled results, the Zw locus mapped to 62.9 on the X chromosome relative to the flanking markers car (at 62.5) and sw (at 64.7). A set of 126 iso-X chromosomal lines of diverse geographic origin was subjected to sequential electrophoresis under three different acrylamide conditions in addition to the conventional starch electrophoretic system. No additional variation beyond the common diallele polymorphism was seen.
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    Behavior genetics 13 (1983), S. 17-27 
    ISSN: 1573-3297
    Keywords: pupation site ; pupation height ; artificial selection ; Drosophila ; density-dependent behavior ; genotype-environment interaction
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    Topics: Biology , Psychology
    Notes: Abstract Selection for increased pupation height was carried out for 17 generations in two lines ofDrosophila simulans derived from a genetically heterogeneous base population. The realized heritability for mean pupation height in each line, calculated over the 17 generations, did not differ significantly from zero. Both selected lines tended to pupate away from the center of the culture medium to a greater extent than the control in the latter generations of the experiment but not in earlier generations. Pupation height may have been refractory to artificial selection because of an adaptation of this species to pupate on the larval food source. In a subsequent experiment, each line was tested at three larval densities in an apparatus different from the one used for selection. Each successively higher density showed a corresponding increase in pupation height. Both selected lines had higher mean pupation heights than the control line. The differences between lines became more pronounced as the larval density increased.
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    Biochemical genetics 21 (1983), S. 365-374 
    ISSN: 1573-4927
    Keywords: alcohol dehydrogenase ; NAD+ levels ; Drosophila
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    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract Previous studies carried out in mammalian systems indicated that an organism's NAD+/NADH balance is carefully regulated but can be destabilized by dietary stresses. Since Drosophila alcohol dehydrogenase (ADH) uses NAD+ to remove a hydrogen from ethanol in the first step of alcohol catabolism, it is possible that under alcohol stress conditions the in vivo NAD+ levels in Drosophila may decrease. In this study genetically homozygous flies were stressed with maximally sublethal concentrations of ethanol (10%) for periods of up to 24 hr. The results indicate that NAD+ levels do in fact drop by at least 20% in response to ethanol stress. Evidence is presented that suggests that this decrease is the direct result of ADH-mediated catabolism.
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    Behavior genetics 22 (1992), S. 469-487 
    ISSN: 1573-3297
    Keywords: courtship ; pheromones ; Drosophila ; apterous ; juvenile hormone ; reproductive development ; sexual behavior
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    Topics: Biology , Psychology
    Notes: Abstract Theapterous (ap) gene ofDrosophila melanogaster exhibits extreme pleiotrophy: its functioning is essential for life, normal wing structure, juvenile hormone production, female fertility, and normal development of female sexual receptivity. Four mutantap alleles (ap 4,ap 56f,ap c, andap blt) were characterized for three additional phenotypes: male mating success, courtship behavior, and immature male sex appeal (the ability of males to stimulate homosexual cortship). Mating success with mature wild-type virgin females is reduced in males mutant for theap gene, the extreme case beingap 4/ap 4 males, which are behaviorally sterile. Inap mutants, nonwing courtship elements are qualitatively like those ofap +/ap + males. However, the mean rate of nonwing courtship directed toward virgin wild-type females (i.e., the mean temporal frequency of these displays) is reduced in males homozygous forap 4,ap 56f, orap c alleles. In contrast, theap blt allele makes for wild-type rates of nonwing courtship. Immature male sex appeal persists for at least 3 days in males homozygous forap c and, to a lesser extent, inap 56f orap 4 homozygotes;ap blt/ap blt and wild-type males lose immature male sex appeal after 1 day. All three male phenotypes map to theap locus, which is therefore essential for the development of normal levels of male courtship and male mating success and for the timely loss of immature male sex appeal. For each phenotype,ap + is dominant toap alleles making for behavioral abnormalities, with a single exception (for rate of nonwing courtship,ap +/ap c was low). For mating success and frequency of nonwing courtship, each allele pair exhibits at least partial complementation, except forap 4 andap 56f, which fail to complement. For immature male sex appeal,ap c,ap 4, andap 56f fall into the same complementation group. Juvenile hormone production is not correlated with effects on male reproductive behavior.
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    Behavior genetics 22 (1992), S. 557-573 
    ISSN: 1573-3297
    Keywords: Drosophila ; biometrical analysis ; behavior genetics ; genetic analysis ; ss a ; deletion mapping
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    Topics: Biology , Psychology
    Notes: Abstract The homeotic mutationspineless-aristapedia (ss a ) transforms the aristae into second tarsi. Flies with aSS a phenotype also show extremely positive geotaxis as measured in a Hirsch-type geotaxis maze. Other antennal mutants and flies with their aristae amputated do not show such extreme positive geotaxis. Deletion analysis has comapped the geotaxis effect withSS a in band 89C on the third chromosome. Finally, a biometrical analysis has detected additional genes on the X chromosome that also affects geotaxis.
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    Biochemical genetics 30 (1992), S. 159-168 
    ISSN: 1573-4927
    Keywords: Drosophila ; indirect flight muscle ; tropomyosin ; polymorphism
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    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract We describe polymorphism in aDrosophila indirect flight muscle-specific tropomyosin isozyme, named TnH-34. Three variants of this protein differ in their mobilities as determined by 1-D and 2-D SDS-PAGE. Meiotic mapping places the polymorphism close to, if not within, the structural gene encoding this tropomyosin isozyme. The most likely site of the mutations is within a single C-terminal exon. Flight-testing of different genotypes reveals that this variation in TnH-34 does not affect flight ability. These results suggest that some sequence variation may be tolerated in this section of the protein and correlate with the variability of this protein in different insect species.
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    Biochemical genetics 30 (1992), S. 305-315 
    ISSN: 1573-4927
    Keywords: Drosophila ; diaphorase ; purification ; kinetics ; immunochemical characteristics
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    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract Diaphorase-1 and diaphorase-2 were isolated from twoDrosophila species,D. virilis andD. melanogaster, and purified by gel filtration, affinity chromatography, immunoaffinity chromatography, and ion-exchange chromatography. The molecular weights of both enzymes were the same in each species. The molecular weight of diaphorase-1 was the same under both denaturating and nondenaturating conditions, close to 60,000, indicating a monomeric structure. Sodium dodecyl sulfate (SDS) electrophoresis of the purified diaphorase-2 revealed the presence of a single protein band of 55,000 Da, while the molecular weight of the native enzyme was found to be 67,000. The two diaphorases were further characterized by their pH optima, isoelectric points, and kinetic parameters, and antibodies were raised in rabbits against the purified enzymes fromD. virilis. The antibodies showed no cross-reactions but recognized the corresponding diaphorases inD. melanogaster andD. novamexicana as well asD. virilis. The data obtained confirmed the hypothesis of an independent genetic control of diaphorase-1 and diaphorase-2 inDrosophila.
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    Biochemical genetics 30 (1992), S. 305-315 
    ISSN: 1573-4927
    Keywords: Drosophila ; diaphorase ; purification ; kinetics ; immunochemical characteristics
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    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract Diaphorase-1 and diaphorase-2 were isolated from twoDrosophila species,D. virilis andD. melanogaster, and purified by gel filtration, affinity chromatography, immunoaffinity chromatography, and ion-exchange chromatography. The molecular weights of both enzymes were the same in each species. The molecular weight of diaphorase-1 was the same under both denaturating and nondenaturating conditions, close to 60,000, indicating a monomeric structure. Sodium dodecyl sulfate (SDS) electrophoresis of the purified diaphorase-2 revealed the presence of a single protein band of 55,000 Da, while the molecular weight of the native enzyme was found to be 67,000. The two diaphorases were further characterized by their pH optima, isoelectric points, and kinetic parameters, and antibodies were raised in rabbits against the purified enzymes fromD. virilis. The antibodies showed no cross-reactions but recognized the corresponding diaphorases inD. melanogaster andD. novamexicana as well asD. virilis. The data obtained confirmed the hypothesis of an independent genetic control of diaphorase-1 and diaphorase-2 inDrosophila.
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    Biochemical genetics 30 (1992), S. 77-83 
    ISSN: 1573-4927
    Keywords: acetylcholinesterase ; insecticide ; resistance ; Drosophila
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    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract Selection of field populations originating from several countries allowed us to isolate 13 strains ofDrosophila melanogaster resistant to parathion.In vitro studies of acetylcholinesterase inhibition by paraoxon have been carried out on purified enzymes: most of the resistant strains harbor an altered acetylcholinesterase. Enzymes with higher resistance levels have been characterized with respect to their cross-resistance toward several insecticides. The patterns obtained have permitted us to group them and to delineate four categories. The existence of four distinct types of protein suggests that several mutations of acetylcholinesterase are responsible for insecticide resistance inDrosophila.
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  • 41
    ISSN: 1573-4927
    Keywords: Drosophila ; glycerol-3-phosphate dehydrogenase ; restriction map ; duplication ; enzyme activity
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    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract Restriction site variation in a 25-kb region including thesn-glycerol-3-phosphate dehydrogenase (Gpdh) locus has been assessed in 29 single femaleD. melanogaster lines from the Cardwell (Australia, QLD) population. TheGpdh locus was duplicated in about one-third of the lines, although the duplication was incomplete and lacked exons 1 and 2. There was no restriction site variation in the duplicated region. Three insertions were found in the gene region but only one affected GPDH activity. The lines with the duplication had higher levels of GPDH activity and protein amount than did nonduplicated lines. This effect was also observed in lines extracted from two other Australian populations. The duplication is shown to have a similar structure in each population investigated and is also present in populations from China and Africa. It is suggested that the effect of the duplication on GPDH activity, which might be due to structural factors affecting transcription at theGpdh locus, could account for the worldwide distribution of the duplication.
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    Biochemical genetics 30 (1992), S. 515-527 
    ISSN: 1573-4927
    Keywords: glutathioneS-transferase ; Drosophila ; cellular detoxification ; pesticide resistance ; insect metabolism
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    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract We have isolated aDrosophila gene,DmGST-2, that encodes glutathioneS-transferase, a homo- or heterodimeric enzyme thought to be involved in detoxification of xenobiotics, including known carcinogens. The encoded protein has a primary sequence that is more similar to mammalian placental and nematode GSTs than that of a previously describedDrosophila GST gene, herein referred to asDmGST-1. We provide a physical map of the gene and show that it specifies at least two mRNAs, measuring 1.9 and 1.6 kb, which differ only in the lengths of their 3′ untranslated regions. Both of the mRNAs are present during all developmental stages.In situ hybridization of theDmGST-2 gene to larval polytene chromosomes places it within the 53F subdivision of chromosome 2, and Southern blotting to chromosomal DNA indicates that the gene has no close relatives within theDrosophila genome. Our results make possible molecular genetic approaches for further elaborating the function of glutathioneS-transferases in insect development and physiology, in the metabolism of plant toxins, and in conferring insecticide resistance.
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    Theoretical and applied genetics 83 (1992), S. 821-826 
    ISSN: 1432-2242
    Keywords: Drosophila ; Balancers ; Inversions ; Translocations ; Meiosis
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    Topics: Biology
    Notes: Summary We used a screen for maternally generated late embryonic lethals as a new method for the isolation of inversions that are suitable for the balancing of mutations in Drosophila hydei. The recovery of several inversions by this method demonstrates that female meiosis in D. hydei apparently differs from meiosis in female D. melanogaster, since in D. hydei the defective chromosomes which are generated by a single crossing-over within a paracentric inversion can be recovered via the egg nucleus. In addition, the classic method of crossingover suppression was used in order to isolate more inversions and to improve the balancing capacities of inversions. We succeeded in constructing chromosomes that allow the balancing of mutations on nearly the whole genome of D. hydei. We discuss here whether or not this method is suited for application to other organisms.
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    Theoretical and applied genetics 65 (1983), S. 173-180 
    ISSN: 1432-2242
    Keywords: Disruptive selection ; Linkage disequilibrium ; Genetic variance ; Drosophila
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    Topics: Biology
    Notes: Summary Theoretical predictions of changes in variance with disruptive selection have used models of infinitely many genes so the increase in variance was necessarily due to linkage disequilibrium. With small numbers of loci, the disequilibrium is shown still to comprise the major part of the changes in variance. In a replicated experiment with Drosophila melanogaster, disruptive selection was practised for three generations, and this was followed by 5 or 7 generations of random mating. The heritability, as estimated from regression of progeny on parent, rose from 37% to 68% on selection, and subsequently declined to 45% on random mating. Changes of variance can be interpreted invoking the build up of linkage disequilibrium during selection followed by its breakdown upon relaxation. The results agree well with those obtained from Monte Carlo simulation.
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  • 45
    ISSN: 1432-2242
    Keywords: Drosophila ; Enzyme polymorphisms ; Latitudinal clines
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    Topics: Biology
    Notes: Summary The octanol dehydrogenase (Odh) and acid phosphatase (Acph) loci of Drosophila melanogaster are each polymorphic for two electrophoretically detectable alleles. The frequencies of the Odh and Acph alleles have been analysed in populations sampled from up to a 40 ° latitudinal range in each of Australasia, North America and Europe/Asia. Odh S frequency is found to be significantly negatively associated with distance from the equator in all three zones. The relationship of Acph S frequency to distance from the equator is significant and negative in Australasia but neither significant nor consistent in sign in North America and Europe/Asia.
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    Evolutionary ecology 6 (1992), S. 342-351 
    ISSN: 1573-8477
    Keywords: Drosophila ; polymorphism ; aggregation ; ephemeral patches ; soft selection
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    Topics: Biology
    Notes: Summary Many models have been proposed in which environmental heterogeneity promotes genetic diversity. Such models describe the situation where different phenotypes have different fitness values in different types of patch and are the genetic equivalent of the traditional resource partitioning models in ecology which allow the coexistence of species. Here we construct a different type of cellular model in which polymorphisms in populations ofDrosophila can be maintained without traditional resource partitioning. Parameter values taken from laboratory and field observations represent fungal breedingDrosophila. Some stochasticity is used in the description of the migration between patches. In the model space is divided into a uniform matrix of cells each of which has the potential to contain an ephemeral resource item (fungal fruiting body). Square arenas of up to 400 cells were used. Genotypes arrive at a fresh site, breed (Hardy-Weinberg equilibrium) and lay eggs. The eggs hatch and the larvae compete using the Hassell-Comins competition equations, as if they were three different species. Adult emergents all migrate to an adjacent cell. The aggregation patterns observed in nature are produced using an ‘attraction probability’ where each fly has a chance of moving to the currently most densely populated adjacent patch. This ‘black box’ description of migration produces distribution patterns which are indistinguishable from those seen in wild populations of fungal breedingDrosophila. Results show that the ‘attraction probability’ is the key factor in the maintenance of polymorphism and that even when the competitive advantage of the superior genotype is very great, polymorphisms can be maintained.
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    Hydrobiologia 100 (1983), S. 169-201 
    ISSN: 1573-5117
    Keywords: rotifers ; saprobity ; saprobic valence ; indicative weight of species ; saprobic index ; pollution
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    Topics: Biology
    Notes: Abstract Six hundred and twenty species and lower taxonomical units of Rotatoria found in Czechoslovakia and surrounding countries are listed alphabetically and classified according to water quality. The numerical characteristics include the saprobic valence in 10 balls, the indicative weight of species, Ii, and the individual saprobic index, Si. Rotifers are considered to be good indicators and some of them are figured on Plates 1–3. The situation is illustrated by four graphs and the relation to BOD5 values is stressed. All rotifers are aerobic organisms and occur only within limnosaprobity. They can also serve as indicators of trophic conditions. To characterize the situation in standing and slowly flowing waters a Brachionus: Trichocerca quotient is proposed. Rotifers can also be used as test organisms in toxicity experiments.
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    Biochemical genetics 30 (1992), S. 159-168 
    ISSN: 1573-4927
    Keywords: Drosophila ; indirect flight muscle ; tropomyosin ; polymorphism
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract We describe polymorphism in aDrosophila indirect flight muscle-specific tropomyosin isozyme, named TnH-34. Three variants of this protein differ in their mobilities as determined by 1-D and 2-D SDS-PAGE. Meiotic mapping places the polymorphism close to, if not within, the structural gene encoding this tropomyosin isozyme. The most likely site of the mutations is within a single C-terminal exon. Flight-testing of different genotypes reveals that this variation in TnH-34 does not affect flight ability. These results suggest that some sequence variation may be tolerated in this section of the protein and correlate with the variability of this protein in different insect species.
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  • 49
    ISSN: 1573-4927
    Keywords: Drosophila ; glycerol-3-phosphate dehydrogenase ; restriction map ; duplication ; enzyme activity
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    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract Restriction site variation in a 25-kb region including thesn-glycerol-3-phosphate dehydrogenase (Gpdh) locus has been assessed in 29 single femaleD. melanogaster lines from the Cardwell (Australia, QLD) population. TheGpdh locus was duplicated in about one-third of the lines, although the duplication was incomplete and lacked exons 1 and 2. There was no restriction site variation in the duplicated region. Three insertions were found in the gene region but only one affected GPDH activity. The lines with the duplication had higher levels of GPDH activity and protein amount than did nonduplicated lines. This effect was also observed in lines extracted from two other Australian populations. The duplication is shown to have a similar structure in each population investigated and is also present in populations from China and Africa. It is suggested that the effect of the duplication on GPDH activity, which might be due to structural factors affecting transcription at theGpdh locus, could account for the worldwide distribution of the duplication.
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  • 50
    ISSN: 1617-4623
    Keywords: Drosophila ; Muscle proteins ; Paramyosin ; Leucine zippers ; Differential polyadenylation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Several cDNA clones encoding the complete Drosophila paramyosin sequence, including two potential polyadenylation sites, have been obtained. Southern analysis and in situ hybridization to polytene chromosomes indicate that in Drosophila the paramyosin gene is single copy, located on the left arm of the third chromosome at region 66D14. Northern analyses show predominantly two different RNAs which are the products of the choice between the two alternative polyadenylation sites. The two species begin to be synthesized around 10 h of development when embryonic muscles are formed, expression peaking at the end of embryogenesis. The protein is first expressed at germ band shortening in association with muscle precursor cells. A second maximum of paramyosin RNA expression occurs at late pupal stages when the higher molecular weight form becomes more abundant. In young adults this species becomes the main transcript detected. The 102 kDa polypeptide sequence is highly similar to that of Caenorhabditis elegans paramyosin. The protein has a central α-helical coiled-coil rod, organized in 29 groups of four typical seven-residue repeats and flanked by two short non-α-helical regions. Several leucine zippers are located on the hydrophobic face of the α-helix in paramyosin which, together with disulfide bonds between cysteines, are probably involved in the stabilization of the dimer. The structural and functional properties of Drosophila paramyosin deduced from the sequence are compared with those of known invertebrate myosins and paramyosins.
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  • 51
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    Molecular genetics and genomics 235 (1992), S. 441-449 
    ISSN: 1617-4623
    Keywords: Drosophila ; Gene regulation ; Transcription ; Transposable element
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    Topics: Biology
    Notes: Summary Two spontaneous mutations of rudimentary, the gene encoding the first steps of de novo pyrimidine biosynthesis in Drosophila, are suppressed by mutant alleles of the suppressor of Hairy-wing locus. This interaction differs from typical su(Hw) suppression in that neither rudimentary allele is associated with an insertion of the gypsy retrotransposon. One allele, r sP1, appears to be a point mutation. Adult r sP1 homozygous females accumulate substantially less 7.3 kb rudimentary transcript than do wild-type females. The other allele, r sP2, is an insertion of an mdg3 retrotransposon in the sixth exon of rudimentary and in the opposite transcriptional orientation. This insertion divides the rudimentary locus into two separate, yet functional, transcription units by truncating transcription from the rudimentary promoter and promoting transcription of downstream rudimentary sequences. Phenotypic suppression of both r sP1 and r sP2 by mutant alleles of the suppressor of Hairy-wing locus correlates with enhanced levels of the r sP1 and r sP2 transcripts.
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  • 52
    ISSN: 1617-4623
    Keywords: Phosphoglycerate kinase ; Drosophila ; Nucleotide sequence ; Glycolysis
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    Topics: Biology
    Notes: Summary The gene that encodes phosphoglycerate kinase in Drosophila melanogaster (Pgk) has been isolated and characterized. There is a single copy of Pgk in the Drosophila genome located at cytogenetic position 23A1-2. Transcripts of Pgk are 1.6 kb long and are found during development with a profile similar to the expression pattern of other genes of the glycolytic pathway. There are substantial amounts of maternal transcript in early embryos which decline in abundance until mid-embryogenesis when transcript levels increase; levels remain high, during larval stages, fall during pupariation and rise again at emergence. The nucleotide sequence of the Pgk gene reveals two small introns, one of which is at a position identical to the site of an intron found in Pgk genes from other organisms. The Pgk gene has no TATA box in the region of transcription initiation and has multiple transcription initiation sites that are closely spaced within 110 nucleotides of the translation start site.
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  • 53
    ISSN: 1617-4623
    Keywords: Dosage compensation ; LSPI-α ; L12 ; Drosophila
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    Topics: Biology
    Notes: Summary The X-linked geneLSPI-α ofDrosophila melanogaster, expressed in the third larval instar, does not exhibit dosage compensation at its normal locus but does compensate when it is relocated to ectopic sites on the X chromosome. A transcription unit designatedL12, which is active in the second larval instar and capable of encoding a putative protein of 28.5 kDa, lies immediately downstream fromLSPI-α. We have determined thatL12 is dosage compensated by measuring the steady-state level of its transcript in male and female larvae. The difference in response of these two adjacent genes should be taken into consideration when models of the mechanism of dosage compensation are formulated.
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  • 54
    ISSN: 1617-4623
    Keywords: Antibacterial ; Digestion ; Drosophila ; Gene family ; Lysozyme
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    Topics: Biology
    Notes: Summary As part of a study of the genes involved in antibacterial defense in Drosophila melanogaster, we have isolated genomic clones harboring a family of chicken-type lysozyme genes, using a lepidopteran lysozyme cDNA as probe. The locus was mapped to the cytological location 61F1-4 on the third chromosome and two of the genes at this locus, LysD and LysP, were analyzed in detail. In contrast to the bacteria-induced lysozymes in the hemolymph of many insects, the transcription levels of both Drosophila genes decrease after bacterial injections into the hemocoel. Apparently, these gene products, like the specifically adapted lysozymes in mammalian foregut fermenters, have been recruited for the digestion of bacteria present in fermenting food. The LysD gene is expressed in an anterior section of the midgut during all feeding stages of development in both larvae and adults. The LysP gene is only active in the adult where it is expressed in the salivary glands. The transcription units for both genes are very compact and they lack introns. Lysozyme D is unusual in that it is predicted to have an acidic isoelectric point whereas lysozyme P appears to be a typical basic lysozyme.
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  • 55
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    Hydrobiologia 107 (1983), S. 35-45 
    ISSN: 1573-5117
    Keywords: zooplankton ; rotifers ; laboratory culture ; life table ; population dynamics
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    Topics: Biology
    Notes: Abstract A new culture method for K. cochlearis has made it possible to study isolated animals and to investigate the population dynamics of this pelagic rotifer species. The duration of principal developmental stages diminishes continuously with temperature. Decreased survival was associated with a reduced duration of individual fecundity. The age distribution of the population shifted toward younger age intervals with higher temperatures. Growth rates had an optimum at 15°C; the population dynamics, while lower for K. cochlearis than for some other rotifers, were in good agreement with field data.
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  • 56
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    Hydrobiologia 107 (1983), S. 47-50 
    ISSN: 1573-5117
    Keywords: rotifers ; laboratory culture ; defined medium ; Keratella cochlearis
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    Topics: Biology
    Notes: Abstract Procedures for the continuous laboratory culture of Keratella cochlearis in a defined medium and upon an algal food are described. Culturing success appears to be a function of food availability as well as composition. This availability requirement is satisfied by the use of test tubes and inverted titration plate concavities as culture vessels. The satisfactory culture medium contains an ammonia compound as a nitrogen source.
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  • 57
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    Hydrobiologia 237 (1992), S. 93-101 
    ISSN: 1573-5117
    Keywords: rotifers ; Mali ; ecology ; biogeography ; Africa
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    Topics: Biology
    Notes: Abstract In samples collected from different parts of the Republic of Mali (W-Africa), ninety-two taxa of rotifers were identified. Some were present in different forms; 56% were cosmopolitan, 19% thermophilous with a wide distribution, 20% tropicopolitan and 5% cold-stenothermous. These latter species seem to be relicts of palaeoclimatic conditions in Africa.
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  • 58
    ISSN: 1573-5117
    Keywords: eutrophication ; lake restoration ; zooplankton grazing ; rotifers ; crustaceans ; P-loading ; P-excretion
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    Topics: Biology
    Notes: Abstract The paper summarizes the results of a ten-year (1981–1991) zooplankton research on the Lake Loosdrecht, a highly eutrophic lake. The main cause of the lake's eutrophication and deteriorating water quality was supply up to mid 1984 of water from the River Vecht. This supply was replaced by dephosphorized water from the Amsterdam-Rhine Canal in 1984. The effects of this and other restoration measures on the lake's ecosystem were studied. Despite a reduction in the external P-load from ca. 1.0 g P m−2 y−1 to ca. 0.35 g m−2 y−1 now, the filamentous prokaryotes, including cyanobacteria and Prochlorothrix, continue to dominate the phytoplankton. Among the crustacean plankton Bosmina spp, Chydorus sp. and three species of cyclopoid copepods and their nauplii are quite common. Though there was no major change in the composition of abundant species, Daphnia cucullata, which is the only daphnid in these lakes, became virtually extinct since 1989. Among about 20 genera and 40 species of rotifers the important ones are: Anuraeopsis fissa, Keratella cochlearis, Filinia longiseta and Polyarthra. The rotifers usually peak in mid-summer following the crustacean peak in spring. The mean annual densities of crustaceans decreased during 1988–1991. Whereas seston (〈 150 µm) mean mass in the lake increased since 1983 by 20–60%, zooplankton (〉 150 µm) mass decreased by 15–35%. The grazing by crustacean community, which was attributable mainly to Bosmina, had mean rates between 10 and 25% d−1. Between 42 and 47% of the food ingested was assimilated. In spring and early summer when both rotifers and crustaceans have their maximal densities the clearance rates of the rotifers were much higher. Based on C/P ratios, the zooplankton (〉 150 µm) mass contained 2.5 times more phosphorus than seston (〈 150 µm) mass so that the zooplankton comprised 12.5 % of the total-P in total particulate matter in the open water, compared with only 4.5% of the total particulate C. The mean excretion rates of P by zooplankton varied narrowly between 1.5 and 1.8 µg P 1− d−1, which equalled between 14 and 28% d−1 of the P needed for phytoplankton production. The lack of response to restoration measures cannot be ascribed to one single factor. Apparently, the external P-loading is still not low enough and internal P-loading, though low, may be still high enough to sustain high seston levels. Intensive predation by bream is perhaps more important than food quality (high concentrations of filamentous cyanobacteria) in depressing the development of large-bodied zooplankton grazers, e.g. Daphnia. This may also contribute to resistance of the lake's ecosystem to respond to rehabilitation measures.
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    Hydrobiologia 106 (1983), S. 107-114 
    ISSN: 1573-5117
    Keywords: subtropical ; Monogononta ; California ; Florida ; Bahamas ; rotifers
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    Topics: Biology
    Notes: Abstract Two new rotifer species, Lecane (Monostyla) aliger n.sp. and Proales pugio n.sp. are described from the Bahama Islands, Florida and California, and their autecology outlined. Some other rare rotifers are discussed which also prefer subtropical conditions. They are: Epiphanes clavulata, Epiphanes brachionus spinosus, Lecane crepida and Proalides tentaculatus tentaculatus. The existence of subtropical rotifer associations is discussed and supported by ecological data.
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  • 60
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    Hydrobiologia 240 (1992), S. 133-141 
    ISSN: 1573-5117
    Keywords: microplankton ; rotifers ; arctic lakes
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    Topics: Biology
    Notes: Abstract Microplankton community structures and abundance was assessed in lakes at the Toolik Lake LTER site in northern Alaska during the summers of 1989 and 1990. The microplankton community included oligotrich ciliates, but rotifers and zooplankton nauplii comprised greater than 90% of total estimated heterotrophic microplankton biomass. Dominant rotifer taxa included Keratella cochlearis, Kellicottia longispina, Polyarthra vulgaris, Conochilus unicornis and a Synchaeta sp. Microplankton biomass was lowest in highly oligotrophic Toolik Lake (〈 5 µgCl−1 at the surface) and highest (up to 55 µCl−1) in the most eutrophic lakes, experimentally fertilized lakes, and fertilized limnocorrals, consistent with bottom-up regulation of microplankton abundance.
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  • 61
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    Hydrobiologia 104 (1983), S. 181-190 
    ISSN: 1573-5117
    Keywords: rotifers ; genetics ; brachionidae ; mating behaviour ; resting eggs ; literature review
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    Topics: Biology
    Notes: Abstract Crossbreeding experiments with three geographically distinct strains (E, S, and L) of the rotifer Brachionus plicatilis have been carried out in an attempt to elucidate the apparent male sterility of strain L, which is unable to produce resting eggs. The 9 crossing possibilities of the three strains have been investigated in 27 experiments. The results refute the concept of male sterility. L-males copulate successfully with mictic as well as with amictic females of strains E and S. Fertilized amictic E and S females produce defective resting eggs, which have only one thin shell and, which disintegrate after deposition. L-females cannot, as a rule, be fertilized. Moreover, crosses between strain E and S are succesful only in one direction; the reciprocal crosses failed. To explain the present results a hypothesis is suggested that the thickness of the body wall of newborn females differs in the three strains, and between mictic and amictic individuals. A sequence of gradually increasing body wall thickness of all types of females involved, together with a comparably increasing penetration ability of the males of strain E, S, and L explains the success or failure of all crosses, including the unilateral cross E × S.
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  • 62
    ISSN: 1573-5117
    Keywords: rotifers ; Brachionus calyciflorus ; phototaxis ; sensory pigment ; accessory pigment ; microspectrophotometry ; absorption spectrum ; spectral sensitivity
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    Topics: Biology
    Notes: Abstract The observed wavelength-dependent variations in the phototaxis of the rotifer Brachionus calyciflorus inform us only partially about the spectral characteristics of the sensory pigment of the eye, since these variations are also linked to the absorption spectrum of the accessory pigment(s). The absence of phototaxis between 420 nm and 500 nm is due to the lack of sensitivity of the sensory pigments at these wavelengths The absence of response between 650 nm and 700 nm is due to a drop in the absorbance of the accessory pigments, which consequently no longer play a screening role at these wavelengths The existence of oriented responses between 350 nm and 420 nm and between 500 nm and 650 nm, is due to the joint intervention of the two types of pigments at these wavelengths
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  • 63
    ISSN: 1573-5117
    Keywords: rotifers ; sensory receptor ; feeding behaviour ; scanning electron microscopy ; transmission electron microscopy
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    Notes: Abstract A study of the anterior sensory receptors of male and female Asplanchna brightwelli by scanning electron microscopy reveals some important differences in the region surrounding the mouth. In the male, the ventrolateral sensory bristles, the pseudotrochus, the inner and the outer buccal tufts and the mastax receptors are absent. The oral receptors are reduced. Transmission electron microscopy of these receptors shows that they consist of ciliated sensory cells surrounded by epithelial supporting cells. The distal ends of the cilia of the mastax receptors are modified; the cilia of the other receptors differ only in their length and rootlet structure from the locomotor cilia of the cingulum. A consideration of the feeding behaviour of Asplanchna leads us to suppose that these sensory cilia function in mechanoreception and in chemoreception.
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  • 64
    ISSN: 1573-5117
    Keywords: rotifers ; automatic tracking ; analysis of swimming behaviour ; video recording ; computer programs ; speed of swimming ; rate of change of direction
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    Notes: Abstract An automatic tracking system for rotifer swimming movements is described. The x and y coordinates of the Center of gravity of the animal are stored in the computer memory every twelfth of a second. Computer programs were developed to analyze the data and to calculate the average and the standard deviation for the following parameters per unit of time: distance traveled, turning angles toward the right and toward the left, distance from the point of departure as the crow flies. Histograms are traced by the computer showing the distribution of these values, as well as their evolution with time. This experimental system is dependable. The first values which we obtained for the swimming speed of rotifers correspond well with those which are given in the literature. The other parameters had not been measured until now.
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    Hydrobiologia 104 (1983), S. 225-227 
    ISSN: 1573-5117
    Keywords: rotifers ; temperature change ; morphology ; Brachionus population dynamics
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    Topics: Biology
    Notes: Abstract The influence of parental culture temperature regime on population parameters of offspring was investigated. Fecundity and net reproduction are influenced by the temperature conditions of the previous generation.
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  • 66
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    Hydrobiologia 104 (1983), S. 229-230 
    ISSN: 1573-5117
    Keywords: rotifers ; Monogononta ; distribution ; pollution
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  • 67
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    Hydrobiologia 104 (1983), S. 213-224 
    ISSN: 1573-5117
    Keywords: rotifers ; resting eggs ; dormancy ; hatching ; production ; morphology ; evolution
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    Topics: Biology
    Notes: Abstract The biology of resting eggs of monogonont rotifers is reviewed, covering literature published since the last major review by Gilbert (1974). The topics examined include resting egg production, morphology and species specificity, hatching, and evolutionary significance. Four major determinants of resting egg production are identified: mictic female production, male activity and fertility, female susceptibility to fertilization, and fertilized female fecundity. Recent work in these four areas is discussed as well as resting egg production in natural populations. Resting egg morphology, particularly shell structure and internal organization, is compared among species. Recent reports on the control of resting egg hatching in the laboratory are examined and the importance of temperature, light, diet, and salinity is reviewed. Two hatching patterns are contrasted, the first where eggs hatch at regular intervals over extended periods and the second where hatching is synchronized to some environmental cue. A latent period after resting egg formation, during which no hatching occurs, is defined for several species. The adaptive features of resting eggs are outlined including their contribution to genetic variability through recombination, their provision for environmental escape by dormancy, and their colonizing function resulting from their ease of dispersal. The type of cue utilized to initiate mictic female production as well as the pattern of resting egg hatching is related to environmental predictability.
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    Hydrobiologia 104 (1983), S. 231-236 
    ISSN: 1573-5117
    Keywords: rotifers ; phosphorus ; nitrogen ; excretion ; temperature ; body weight
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    Topics: Biology
    Notes: Abstract Two series of experiments were carried out to determine the relation of the rate of phosphorus and nitrogen excretion by the planktonic rotifers to ambient temperature and individual body weights of these animals. The following formulas describing this relation were obtained: EP=0.0154 W−1.27 e0.096T EN=0.0879 W−1.01 e0.088 T, where EP and EN denote the rate of P and N excretion, respectively, in µg · mg dry wt−1 · h−1, W is body weight in µg dry weight, and T is temperature in °C.
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    Hydrobiologia 104 (1983), S. 237-246 
    ISSN: 1573-5117
    Keywords: rotifers ; embryonic development time ; temperature ; ecological significance
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    Topics: Biology
    Notes: Abstract The embryonic development times of four planktonic rotifers from Neusiedlersee (Austria) (Rhinoglena fertöensis, Brachionus calyciflorus, Keratella quadrata and Polyarthra dolichoptera) were determined at constant temperatures ranging from 0.6 °C to 10.5 °C. Development times decreased with increasing temperatures. The curvilinear relationship between temperature and development time was described by Bělehrádek's equation. Data on embryonic development times of rotifers are summarized and regression equations for the temperature-duration of development relationship are presented. Adaptation to temperature is discussed in the context of the thermal history of the various species and populations.
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    Hydrobiologia 104 (1983), S. 247-257 
    ISSN: 1573-5117
    Keywords: rotifers ; dynamics ; biomass ; production ; turnover
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    Topics: Biology
    Notes: Abstract The Rosu, Puiu and Porcu lakes from the Danube Delta are lacustrine ecosystems characterized by a particularly great variation of the biotic and abiotic factors. This variation causes the development of a zooplankton reduced from the point of view of number and biomass, but rich from the taxonomic point of view. Its monthly and annual fluctuations can hardly be correlated to the rest of the plankton fauna and microflora. Rotifer production is low, turnover at the level of plankton rotifers being relatively uniform and dependent on water temperature.
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    Hydrobiologia 104 (1983), S. 259-267 
    ISSN: 1573-5117
    Keywords: rotifers ; rotifer plates ; meromictic lakes ; chemoclines ; rotifer vertical distributions ; photosynthetic bacterial plates ; anaerobiosis
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    Topics: Biology
    Notes: Abstract The vertical distribution of planktonic rotifers has been analysed in relation to season in several meromictic lakes; a coastal lagoon with sea-water intrusion and three dissolution lakes from two karstic systems. Two species, Filinia hofmanni and a form of Anuraeopsis fissa have been found to be more or less restricted to the chemocline or adjacent strata any time they occurred. Many species common in the upper water layers developed large populations near or in the chemocline and more strikingly in summer. Some species had two vertical maxima (one in the surface or the thermocline and another near the chemocline), while others successively shifted their maxima between the upper layers and the chemocline. It is hypothetized that these rotifers are either very versatile or are differentiated as ecotypes, one of them adapted to the chemocline environment. This distribution in a peculiar fluctuating, anoxic, H2S-rich environment poses questions about the biology of those rotifers which there develop extraordinary populations.
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    Hydrobiologia 104 (1983), S. 269-273 
    ISSN: 1573-5117
    Keywords: rotifers ; feeding ; diet ; competition ; niche displacement ; field experiment
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    Topics: Biology
    Notes: Abstract Two rotifers, Polyarthra vulgaris and P. dolichoptera may have different temperature and oxygen optima. In addition, they consume similar foods including Chryptomonadales and Crysomonadales. P. dolichoptera disappeared from the plankton after experimental elimination of fish from a small lake. The disappearance may have been caused by a change in temporal availability of suitable food species (e.g. crysomonads) during early spring. A lack of food during this period, when the water was still cold, may have influenced the competitive balance between the two Polyarthra species.
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    Hydrobiologia 104 (1983), S. 275-278 
    ISSN: 1573-5117
    Keywords: rotifers ; interstitial ; psammon ; distribution ; abundance dynamics ; ecology
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Zonation and abundance dynamics of interstitial rotifers in a semilotic beach of the North Sea island of Sylt were studied in 1975/76. The 13 species investigated prefer the damp sand of the beach slope. The sand flat is only sparsely inhabited. Rotifers only live in oxygen-rich sands. Neither the black sulphite layer in the sand flat nor the groundwater in the beach slope is populated. The family Colurellidae prefers warm temperatures in mid-summer, the family Proalidae colder temperatures in spring and autumn. In contrast to these two families that can be found in different frequencies all year round, the family Dicranophoridae occurs only in the cold seasons and disappears in mid-summer. Possibilities of maintaining the life cycle during these months are discussed.
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    Hydrobiologia 104 (1983), S. 279-291 
    ISSN: 1573-5117
    Keywords: rotifers ; Brachionus plicatilis ; biometry ; ecotypes ; cyclomorphosis
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    Topics: Biology
    Notes: Abstract Univariate comparisons and several multivariate statistical analyses have been performed to study the morphometric variability of B. plicatilis. Both laboratory clones kept under constant conditions and natural populations from different Spanish lagoons and different times of the year have been compared. The results show that not only size, but also allometric coefficients are influenced by environmental factors. However, an important genetic component in the variation of shape and size has been visualized. A clear North-South ordination of the populations of the different lagoons and an important dispersion between their summer populations as well as great differences due to seasonal variation became apparent by the multivariate statistical analysis used.
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    Hydrobiologia 104 (1983), S. 293-296 
    ISSN: 1573-5117
    Keywords: rotifers ; biomass ; dominating species ; relation to trophy
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    Notes: Abstract The number and biomass of rotifers in large eutrophic lakes is small in winter, reaches a maximum in spring or summer and decreases to a winter minimum. The dynamics of rotifer participation as part of total zooplankton is opposite to their absolute number: the role of rotifers in zooplankton is great in winter, starts decreasing in spring, reaches a minimum in summer and increases again to its winter maximum. The number and biomass of rotifers is proportional to the trophy of the waterbody, but in the case of some species this correlation is inverse.
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    Hydrobiologia 104 (1983), S. 367-372 
    ISSN: 1573-5117
    Keywords: rotifers ; Kellicottia longispina ; empty loricas ; Lake Tahoe ; Emerald Bay
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    Topics: Biology
    Notes: Abstract The seasonal dynamics of Kellicottia longispina in Lake Tahoe and an isolated embayment of Lake Tahoe, Emerald Bay, were investigated for an 18-month period in 1977–79. Population birth and death rates were similar in the two systems, although productivity and Mysis relicta densities were higher in Emerald Bay. The timing of population changes was also similar. A major population increase in late winter 1978 was preceded by an increase in egg ratio; the subsequent spring decline of K. longispina was concurrent with decreased birth rates and increased death rates. Empty loricas of K. longispina were occasionally abundant in the plankton samples and seemed to result from K. longispina deaths when densities were high and when egg ratios were declining; it is possible that population senescence was responsible for the high densities of empty loricas observed. A potentially important predator, M. relicta, defecates K. longispina remains in compact fecal pellets; however, it is unlikely that the observed empty loricas resulted from Mysis-related deaths.
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  • 77
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    Keywords: rotifers ; Brachionus ; feeding ; population dynamics ; Anabaena
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    Topics: Biology
    Notes: Abstract The rotifer Brachionus calyciflorus can utilize the cyanobacterium Anabaena flos-aquae as either a sole or supplementary food source in laboratory culture. Positive population growth rates accompany food densities of 10 or 100 µg dry weight ml−1, but slightly negative rates are found at a lower density (1.0 µg ml−1). These results are consistent for rotifers feeding on two strains of A. flos-aquae, UTEX-1444 and NRC-44-1, with slightly enhanced survivorship and reproduction with the latter food. A 1:1 mixture (by dry weight) of Euglena gracilis and A. flos-aquae (NRC-44-1) produces survivorship comparable to that of control rotifer cohorts fed E. gracilis alone, but elicits significantly greater fecundity and population growth rates than found with the control food suspension at the same biomass density.
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  • 78
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    Hydrobiologia 104 (1983), S. 379-383 
    ISSN: 1573-5117
    Keywords: rotifers ; sessile rotifer ; feeding ; in situ ; clearance rate ; filtration rate
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    Topics: Biology
    Notes: Abstract Clearance rates of three sessile and four free-swimming rotifer species from a small acid bog-pond were measured using in situ techniques. Three radioactively labeled cell types, an alga (Chlamydomonas), a bacterium (Enterobacter = Aerobacter), and a yeast (Rhodotorula) were used as tracers. Clearance rates (using yeast) ranged from 〈1.0 to 〉250 µl · animal−1 · h−1 depending on species. Ptygura crystallina, Ptygura pilula, Floscularia conifera, and an unidentified bdelloid ingested all three foods with substantial variation in clearance rates among species and cell type. There was an insignificant error (〈0.3%) in clearance rate associated with non-ingestive uptake of radioactivity. Among the free-swimming taxa, Lecane sp. had a clearance rate of 〈0.5 µl · animal−1 · h−1 on yeast, while another Lecane sp. and Trichotria tetractis did not ingest that cell type.
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  • 79
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    Hydrobiologia 104 (1983), S. 385-396 
    ISSN: 1573-5117
    Keywords: rotifers ; invertebrate predation ; cyclopoid copepod
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    Topics: Biology
    Notes: Abstract Representatives from many taxa including the Protozoa, Cnidaria, Rotifera, Cladocera, Cyclopoida, Calanoida, Harpacticoida, Chaoboridae, and Mysidacea are reported to feed on rotifers. There are few good quantitative data on predation on rotifers by any of these taxa with two exceptions, Rotifera and Cyclopoida. The present review focuses on the dynamics of Cyclopoid copepod predation. Intense and selective cyclopoid copepod predation makes it an important factor to consider in studies of the population ecology and community structure of rotifer populations. Limited information available on other predatory invertebrate taxa suggests that rotifer production may contribute extensively to their diets.
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  • 80
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    Hydrobiologia 104 (1983), S. 19-30 
    ISSN: 1573-5117
    Keywords: rotifers ; biogeography ; dispersal ; continental drift
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    Topics: Biology
    Notes: Abstract The biogeography of rotifers is discussed in light of general biogeographical concepts. It is argued that, in spite of considerable abilities for passive dispersal, vicariance can develop well in this group. Examples selected from the Branchionidae illustrate the high levels of endemicity found in Australia and South America, while the Indian subcontinent and Africa have a predominantly cosmopolitan fauna. An explanation for these patterns is found in drifting continents and Pleistocene climatic changes.
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  • 81
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    Hydrobiologia 104 (1983), S. 175-180 
    ISSN: 1573-5117
    Keywords: rotifers ; Bdelloidea ; life tables ; strategy
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    Notes: Abstract Nine species of Rotifera Bdelloidea have been cultured under laboratory conditions. The species were collected from two different environments: one group from water courses, the other from terrestrial mosses. Life tables have been determined and population dynamics parameters have been calculated. The characteristics of the life history seem to be related to the natural environmental conditions of the species. The patterns of reproductive output may develop as adaptations to different selective pressures: species from unpredictable environments face the probability of leaving no young at all, while species from stable environments are less conservative in their energy budget. Life characteristics are discussed from the point of view of adaptive strategies.
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  • 82
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    Hydrobiologia 104 (1983), S. 307-309 
    ISSN: 1573-5117
    Keywords: rotifers ; ecology ; coal mine water
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    Topics: Biology
    Notes: Abstract The species composition and quantitative structure of the rotifer fauna was investigated in a reservoir containing coal mine water. Only nine mainly planktonic species of rotifers, were found. Two of these were dominating: Brachionus angularis and B. rubens. They are typical indicators of eutrophic waters. Chlorides and sulphates may have an influence on the occurrence and quantitative structure of rotifer assemblages in the investigated reservoir.
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  • 83
    ISSN: 1573-6857
    Keywords: Drosophila ; transposons ; mobility ; inbreeding
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    Topics: Biology
    Notes: Abstract The stability of the elements of eleven transposon families (412, B 104, blood, 297, 1731, G, copia, mdg 4, hobo, jockey and I) has been compared by the Southern technique among individuals of a Drosophila line that has been subjected to 30 generations of sister sib matings. The 412, B104, blood, 297, 1731 and G elements appear stable. Heterochromatic copia and hobo elements and euchromatic I elements appear highly polymorphic. In addition, copia, mdg 4, jockey and I elements undergo an instability resulting in significant variations in relative intensity among autoradiographic bands. The extent of the polymorphisms detected strongly suggests de novo rearrangements of transposable elements.
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  • 84
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    Genetica 86 (1992), S. 37-46 
    ISSN: 1573-6857
    Keywords: Mariner ; Drosophila ; molecular evolution ; transposable element
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    Topics: Biology
    Notes: Abstract The population biology and molecular evolution of the transposable element mariner has been studied in the eight species of the melanogaster subgroup of the Drosophila subgenus Sophophora. The element occurs in D. simulans, D. mauritiana, D. sechellia, D. teissieri, and D. yakuba, but is not found in D. melanogaster, D. erecta, or D. orena. Sequence comparisons suggest that the mariner element was present in the ancestor of the species subgroup and was lost in some of the lineages. Most species contain both active and inactive mariner elements. A deletion of most of the 3′ end characterizes many elements in D. teissieri, but in other species the inactive elements differ from active ones only by simple nucleotide substitutions or small additions/deletions. Active mariner elements from all species are quite similar in nucleotide sequence, although there are some-species-specific differences. Many, but not all, of the inactive elements are also quite closely related. The genome of D. mauritiana contains 20–30 copies of mariner, that of D. simulans 0–10, and that of D. sechellia only two copies (at fixed positions in the genome). The mariner situation in D. sechellia may reflect a reduced effective population size owing to the restricted geographical range of this species and its ecological specialization to the fruit of Morinda citrifolia.
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  • 85
    ISSN: 1573-6857
    Keywords: Drosophila ; transposons ; mobility ; cultured cells
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    Notes: Abstract The genomic distribution and the number of elements of eleven transposon families have been compared by the Southern technique between permanent cultured cells, larval salivary glands and the brains and whole flies of an inbred Drosophila line (inb-c) from which the cells were established. In cultured cells, changes in restriction patterns consistent with various types of rearrangements such as amplification, transposition and excision of the elements of copia, 1731, 412, 297 and mdg-4 transposon families are detected whereas B 104, G and blood elements appear stable. In previous reports these rearrangements were not detected among individuals of the inb-c line or among samples of somatic tissues, or in samples spanning years of maintenance of cultured cells. Hence, we believe that they have been induced de novo during the passage to the cell culture.
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  • 86
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    Genetica 86 (1992), S. 67-84 
    ISSN: 1573-6857
    Keywords: Drosophila ; population genetics ; transposable elements
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract This paper is an attempt to bring together the various, dispersed data published in the literature on insertion polymorphism of transposable elements from various kinds of populations (natural populations, laboratory strains, isofemale and inbred lines). Although the results deal mainly with Drosophila, data on other organisms have been incorporated when necessary to illustrate the discussion. The data pertinent to the regions of insertion, the rates of transposition and excision, the copy number regulation, and the degree of heterozygosity were analysed in order to be confronted with the speculations made with various theoretical models of population biology of transposable elements. The parameters of these models are very sensitive to the values of the transposable element characteristics estimated on populations, and according to the difficulties of these estimations (population not at equilibrium, particular mutations used to estimate the transposition and excision rates, trouble with the in situ technique used to localize the insertions, undesired mobilization of TEs in crosses, spontaneous genome resetting, environmental effects, etc.) it cannot be decided accurately which model better accounts for the population dynamics of these TEs. Tendencies, however, emerge in Drosophila: the copia element shows evidence for deficiency of insertions on the X chromosomes, a result consistent with selection against mutational effects of copia insertions; the P element repartition does not significantly deviate from the neutral assumption, in spite of a systematic copy number of insertions higher on the X than on the autosomes. Data on other elements support either the neutral model of TE containment, neither of the two models, or both. Prudence in conclusion should then be de rigueur when dealing with such kind of data. Finally the potential roles of TEs in population adaptation and evalution are discussed.
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  • 87
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    Genetica 87 (1992), S. 1-6 
    ISSN: 1573-6857
    Keywords: Temperature ; splicing mechanism ; mammals ; Drosophila ; turtles
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Sex determination and differentiation are inherently fascinating to both layperson and geneticist. Major advances have accelerated interest in the molecular genetic events mediating these processes in nematodes, flies, mice and humans. Far less attention has been paid to those organisms, particularly reptiles, where sex is determined by environmental cues. However, recent experimental evidence suggests that the two modes of sex determination may not only share common genetic elements, but may also be regulated by similar mechanisms. We argue that the ability to manipulate sex by temperature provides a particularly suitable model for exploring the molecular basis of this fundamental biological process.
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  • 88
    ISSN: 1573-5117
    Keywords: clearance rates ; assimilation ; copepods ; cladocerans ; rotifers ; oxygen depletion
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    Topics: Biology
    Notes: Abstract The clearance rates of 14 carbon-labelled Chlamydomonas sp. by the copepodite and adult stages of the 2 dominant species of Copepoda were studied in eutrophic Lake Aydat. They varied from 30 to 3,007 µl ind−1 h−1 for Acanthodiaptomus denticornis (mean = 600 µl ind−1 h−1) and from 20 to 1,133 µl ind−1 h−1 for Cyclops vicinus (mean = 340 µl ind−1 h−1). Their maximum assimilation efficiencies were 58% and 50%, respectively. These populations collectively could consume the available food in 4 days during September (maximum daily grazing rate = 24%). Mean individual clearance rates could be ranked Acanthodiaptomus denticornis 〉 Ceriodaphnia quadrangula 〉 Chydorus sphaericus 〉 Daphnia longispina 〉 Cyclops vicinus vicinus 〉 Bosmina longirostris 〉 K. cochlearis 〉 K. quadrata and Kellicottia longispina. Like cladocerans and rotifers, the copepods living in this eutrophic lake can feed at low oxygen concentrations.
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  • 89
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    Hydrobiologia 104 (1983), S. 31-39 
    ISSN: 1573-5117
    Keywords: rotifers ; Brachionus ; India ; biogeography
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The different species and infraspecific categories of the genus Brachionus, so far reported or described from India, are reviewed. Their distribution and taxonomic validity are discussed. Remarks are made on the ecology and epizoic nature of various species.
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  • 90
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    Hydrobiologia 104 (1983), S. 57-60 
    ISSN: 1573-5117
    Keywords: rotifers ; Antarctic ; zoogeography
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    Topics: Biology
    Notes: Abstract An assessment of the distribution of rotifers in the Antarctic and Subantarctic is attempted.
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  • 91
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    Hydrobiologia 104 (1983), S. 49-56 
    ISSN: 1573-5117
    Keywords: rotifers ; Labrador and Newfoundland ; additions to known fauna ; species composition
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    Topics: Biology
    Notes: Abstract One hundred and thirty-one species of rotifers, belonging to 40 genera, are reported from Newfoundland and Labrador, Canada. Of these, 101 are new records for the province and 21 are new records for Canada. Some species exhibited distinct differences from the original descriptions and are figured and discussed. Points of interest in species composition and distribution are noted.
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  • 92
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    Hydrobiologia 104 (1983), S. 41-47 
    ISSN: 1573-5117
    Keywords: rotifers ; diversity ; Australia ; tropical ; community
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Diversity and equitability of rotifer communities from billabongs (oxbows or cut-off meanders) in northern and southeastern Australia are compared. In both areas littoral taxa predominated in open water. Diversity values (Shannon-Wiener, H′) were higher than recorded for tropical assemblages elsewhere. Up to 80 rotifer species co-occurred in Northern Territory billabongs. Brachionids notably were absent; there was an apparent displacement of tropical assemblages into temperate Australia.
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  • 93
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    Hydrobiologia 104 (1983), S. 85-88 
    ISSN: 1573-5117
    Keywords: rotifers ; cryopreservation ; Brachionus plicatilis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Development of techniques to maintain viable rotifer clones in a frozen state would preserve the genotype and reduce routine maintenance for those clones not being actively studied. To this end we have frozen Brachionus plicatilis in dimethyl sulfoxide at concentrations ranging from 6% to 18%. Survival rates decreased as the endpoint temperature was reduced from −20 °C to −45 °C, but did not decrease when the temperature was further reduced to −196 °C (liquid nitrogen). Only 2% of the individuals survived freezing in liquid nitrogen.
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  • 94
    ISSN: 1573-5117
    Keywords: rotifers ; Brachionus plicatilis ; production ; aquaculture
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    Topics: Biology
    Notes: Abstract Brachionus plicatilis were mass cultured using 10 M3,15 m3 and 20 m3 outdoor concrete tanks. Utilization efficiencies for different food combinations using marine yeast (Candida sp., MFD-Y-St.03), baker's yeast and Chlorella sp. for rotifer production were evaluated. With either marine yeast or baker's yeast, addition of Chlorella sp., at 0.5 m3 algal culture day−1 10 m−3 culture volume enhanced rotifer production. Under optimum conditions rotifer density was maintained at more than 450 individuals ml−1.
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  • 95
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    Hydrobiologia 104 (1983), S. 61-69 
    ISSN: 1573-5117
    Keywords: rotifers ; resting eggs ; hatching ; temperature ; salinity ; light ; algae
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Hatching experiments were carried out on a population of Brachionus plicatilis (Dor strain) resting eggs produced in batch laboratory cultures under controlled conditions and then stored for at least one month at 4 °C in the dark. Light was found to be obligatory for termination of dormancy. Over the temperature range of 10–30 °C (at 9.0‰ salinity), hatching was optimal (40–70%) at 10–15 °C and decreased linearly with the rise in incubation temperature. Resting eggs incubated over a salinity range of 9–40‰ (at 15 °C) showed optimal hatching at 16‰. Incubation of resting eggs in distilled water permitted normal embryonic development, but neonates died at eclosion. Presence of algae, Chlorella stigmatophora (0.5 × 106 cell ml−1), was found to aid hatching.
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  • 96
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    Hydrobiologia 104 (1983), S. 71-75 
    ISSN: 1573-5117
    Keywords: rotifers ; recycle ; culture-ecosystem ; Brachionus
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A culture system for the rotifer Brachionus plicatilis was designed to maintain higher food conversion rates and stable population densities. Two 2001 plastic tanks were employed in the culture experiments, tank A for ‘feedback’ culture and tank B for a control culture. The experiments were carried out for 70 days at 24 °C, light intensity, 1500 lux, and a photoperiod of L:D 15:9. B. plicatilis were fed once a day on baker's yeast and Chlorella. Food conversion rates in tanks A and B were 24.7% and 10.1%, respectively. Population density of B. plicatilis in tank A was consistently stable at 100–150 ind. ml−1 throughout the culture period. Density in tank B, however, showed large fluctuations after 40 or 50 days and by the end of the experiment, declined to zero.
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  • 97
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    Hydrobiologia 104 (1983), S. 131-134 
    ISSN: 1573-5117
    Keywords: rotifers ; scanning electron microscopy ; Floscularia ringens ; Asplanchna priodonta
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Scanning electron micrographs have been prepared of two species of rotifer, Floscularia ringens (Linnaeus, 1758) and Asplanchna priodonta Gosse, 1850, from specimens stored in the collections of the British Museum (Natural History) for over seventy years. It is believed that these include the first scanning electron micrographs of a sessile rotifer.
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  • 98
    ISSN: 1573-5117
    Keywords: rotifers ; aging ; Brachionus plicatilis ; swimming behaviour ; calcium ; automatic recording ; computer analysis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The swimming movements of young, middle-aged and old Brachionus plicatilis females, raised in calcium-sufficient and calcium-deficient culture media were recorded automatically. Computer analysis and statistical treatment of the results show that: 1) The middle-aged females swim faster than the young and the old females. In comparison to the middle-aged and the young, old females turn less often and nearly always toward the right, and they do not travel as far from their point of departure as the others 2) When the concentration of calcium in the medium is nearly zero, the swimming speed of middle-aged and old females is slower than that of middle-aged and old females raised in the presence of sufficient amounts of calcium
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  • 99
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    Hydrobiologia 104 (1983), S. 135-139 
    ISSN: 1573-5117
    Keywords: rotifers ; aging ; Lansing Effect ; life history patterns
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The Lansing Effect, simply stated, is that the offspring of old parents tend to have shorter lifespans than the offspring of young parents and in both cases these tendencies are transmitted to successive generations. This statement is difficult to justify from Lansing's data because of the variation in mean lifespan that was observed from one generation to the next. A more precise statement of the Lansing Effect is that isogenic lines derived from young parents tend to persist for more generations than lines derived from old parents. Lansing considered aging to be the result of a factor that was transmitted from mother to offspring via the eggs. He proposed that this factor influences longevity and also alters the pattern of reproduction. Members of short-lived lines derived from old parents reproduced earlier and at higher rates in succeeding generations. In contrast, members of long-lived lines derived from young parents delayed initial reproduction to later age classes in succeeding generations. These proposals are examined using a life table analysis of Lansing's data. The results suggest that the Lansing Effect in Philodina citrina is not due to aging, but rather is the direct result of the changes in fecundity patterns. Accordingly, it would seem prudent to regard the Lansing Effect with some skepticism until more is known about its physiological basis.
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  • 100
    ISSN: 1573-5117
    Keywords: rotifers ; embryogenesis ; organogenesis ; DNA replication
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract DNA synthesis was inhibited during embryogenesis of Habrotrocha rosa with mitomycin C and hydroxyurea. Inhibition of DNA replication in early stages of embryogenesis, at the beginning of organogenesis, just after cavitation of the stomodeum, resulted in a complete inhibition of further development. After this stage of embryogenesis development was insensitive to inhibition of DNA replication.
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