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  • Cell & Developmental Biology  (29)
  • Mitochondria  (5)
  • glycosylation  (5)
  • Evolution  (4)
  • 1
    Electronic Resource
    Electronic Resource
    A new senescence-inducing mitochondrial linear plasmid in field-isolated Neurospora crassa strains from India (1991)
    Springer
    Current genetics 19 (1991), S. 129-137 
    Details
    ISSN: 1432-0983
    Keywords: Senescence ; Plasmid ; Neurospora ; Mitochondria
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Several field-collected strains of Neurospora crassa from the vicinity or Aarey, Bombay, India, are prone to precocious senescence and death. Analysis of one strain, Aarely-1e, demonstrated that the genetic determinants for the predisposition to senescence are maternally inherited. The senescence-prone strains contain a 7-kb, linear, mitochondrial DNA plasmid, maranhar, which is not present in long-lived isolates from the same geographical location. The maranhar plasmid has inverted terminal repeats with protein covalently bound at the 5′ termini. Molecular hybridization experiments have demonstrated no substantial DNA sequence homology between the plasmid and the normal mitochondrial (mtDNA) and nuclear genomes of long-lived strains of N. crassa. Integrated maranhar sequences were detected in the mtDNAs of two cultures derived from Aarey-1e, and mtDNAs with the insertion sequences accumulated during subculturing. Nucleotide sequence analysis of cloned fragments of the two insertion sequences demonstrates that that they are flanked by long inverted repeats of mtDNA. The senescence syndrome of the maranhar strains, and the mode of integration of the plasmid, are reminiscent of those seen in the kalilo strains of N. intermedia. Nonetheless, there is no detectable nucleotide sequence homology between the maranhar and kalilo plasmids.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00326294
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  • 2
    Electronic Resource
    Electronic Resource
    Structure of aGelasinospora linear plasmid closely related to the kalilo plasmid ofNeurospora intermedia (1996)
    Springer
    Current genetics 29 (1996), S. 150-158 
    Details
    ISSN: 1432-0983
    Keywords: Gelasinospora ; Neurospora ; Plasmid ; Mitochondria
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract We have determined the complete nucleotide sequence of a linear mitochondrial plasmid from a natural isolate of a homothallic species ofGelasinospora. The plasmid genome is 8231 by long. It carries terminal inverted repeats of 1137 bp. Extending inwards from the terminal repeats are two long open reading frames coding for putative proteins with similarity to DNA and RNA polymerases. These are separated by a short intergenic region. The plasmid sequence shows remarkable similarity to that of theNeurospora intermedia senescence-plasmid kalilo. Overall the two plasmids have a similar genetic organization and are clearly homologous at the sequence level. The main differences are in the intergenic region and in the terminal repeats.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02221579
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  • 3
    Electronic Resource
    Electronic Resource
    Linear kalilo DNA is a Neurospora mitochondrial plasmid that integrates into the mitochondrial DNA (1989)
    Springer
    Molecular genetics and genomics 220 (1989), S. 113-120 
    Details
    ISSN: 1617-4623
    Keywords: Neurospora ; Senescence ; Mitochondria ; Plasmid ; Kalilo
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The linear autonomous form of kalilo DNA (previously called AR-kalDNA) is shown to be resident within mitochondria rather than nuclei, as had been suggested by previous experiments. This form has been renamed mtAR-kalDNA, to signify its mitochondrial location. Experiments are described that illustrate the inheritance and somatic transmission patterns of the mitochondrial kalilo plasmid and the mitochondrial inserted form of kalilo DNA (mtlS-kalDNA). Progeny of a cross with a pre-senescent subculture as the female parent inherited mtAR-ka1DNA only; mtIS-kalDNA was not transmitted sexually. During somatic propagation of the ascospore cultures, novel kalilo DNA inserts appeared and most of them persisted until death. We propose that these inserts originated from de novo integration of mtAR-kalDNA into the mitochondrial DNA. In two of the ascopore-derived series analyzed, the first inserts detected were seen only transiently and inserts appearing subsequent to the transient inserts were retained until death. We propose that these enduring inserts originated either from rearrangements of the transient inserts or from novel integration events, either from mtAR-kalDNA or from transposition of the transient inserts.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00260864
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  • 4
    Electronic Resource
    Electronic Resource
    Plasmid diversity in senescent and nonsenescent strains of Neurospora (1993)
    Springer
    Molecular genetics and genomics 237 (1993), S. 177-186 
    Details
    ISSN: 1617-4623
    Keywords: Senescence ; Linear plasmids ; Circular plasmids ; Neurospora ; Mitochondria
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary A sample of 171 natural isolates of Neurospora crassa and Neurospora intermedia was tested for senescence. Of these, 28 strains senesced within the duration of the experiment. These senescent strains, together with a selection of nonsenescent strains, were examined for the presence of mitochondrial plasmids. This was done by digesting mitochondrial DNA preparations with proteinase K, and running these samples on agarose gels. Most of the strains examined, both senescent and nonsenescent, contained plasmids, many of them new. Some new plasmids were linear, as inferred from their resistance to 5′ exonuclease and sensitivity to 3′ exonuclease. New circular plasmids were also found. Some strains carry several plasmids, and mixtures of circular and linear elements were common. A cross-homology study was performed on a sample of plasmid-bearing strains, and several cases of apparent relatedness were found, some between strains from distant geographical locations. Linear plasmids homologous to the maranhar linear senescence plasmid were quite common. A new member of the LaBelle circular plasmid homology group was found. In the sample tested for homology, no strains contained elements related to the kalilo linear senescence plasmid. The relationship of the new plasmids to senescence is not known. In addition to plasmid monomers, several different types of derivatives were found. The kalilo linear plasmid was found to occur in linear and circular forms of low mobility, presumed to be giant concatamers, and, in some strains, variant sibling structures and ladders of short derivatives were found. Circular plasmids also gave rise to extensive ladders on electrophoresis, probably representing different relaxation states and head-to-tail concatameric series. Some such forms migrated more slowly than mitochondrial DNA. One unique type of plasmid modification observed was a pair of linear elements that had apparently arisen de novo which showed homology to a circular plasmid.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00282799
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  • 5
    Electronic Resource
    Electronic Resource
    Recombination between heterologous linear and circular mitochondrial plasmids in the fungus Neurospora (1995)
    Springer
    Molecular genetics and genomics 249 (1995), S. 25-36 
    Details
    ISSN: 1617-4623
    Keywords: Neurospora ; Plasmids ; Mitochondria ; Recombination
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A strain of Neurospora intermedia from China contains five prominent extragenomic mitochondrial plasmids: three linear elements called zhisi plasmids, and two circular plasmids, Harbin-1 and -2. In one subculture, levels of four plasmids (all three zhisis and Harbin-1) fell to undetectable values and two novel linear plasmids appeared, Harbin-L and -L2, as well as a new small circular plasmid, Harbin-0.9. Cross-hybridization of restriction fragments and DNA sequencing showed that the Harbin-L plasmid was composed of parts of the circular Harbin-1 plasmid and of one of the linear zhisi plasmids. A model is presented in which the Harbin-1 and zhisi plasmids are present within the same mitochondrion, and crossovers at two separate 7 by sites of sequence identity effectively insert part of the circular Harbin-1 DNA into a zhisi linear plasmid, simultaneously deleting part of the zhisi element. The small plasmid Harbin-0.9 is a fragment of the Har-1 plasmid, and seems to be another product of the recombination process that created Har-L. Recombination of this type could have contributed to the wide array of mitochondrial plasmids found in natural populations of Neurospora.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00290232
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  • 6
    Electronic Resource
    Electronic Resource
    Unique qualities and special problems of the African Great Lakes (1986)
    Springer
    Environmental biology of fishes 17 (1986), S. 161-183 
    Details
    ISSN: 1573-5133
    Keywords: Meromictic ; Evolution ; Diversity ; Cichlidae ; Productivity ; Aquatic reserves ; Flushing ; Pollution ; Fish introductions ; Lake development ; Limnology ; Fishery management ; Conservation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Synopsis The African Great Lakes consist of large, deep rift valley lakes (e.g. Malawi & Tanganyika) and shallower lakes between the Eastern and Western Rifts (e.g. Victoria). They are a group comparable in size to the North American Great Lakes, but are old. Most are seasonally thermally stratified, and wind is the decisive factor that determines the annual cycle of cooling and mixing. Lakes Tanganyika, Malawi and Kivu are meromictic, with deep relict hypolimnia. Large magnitudes and time scales of periodic internal motion, where these have been measured, appear unique among lakes. These lakes harbour the world's richest lacustrine fish faunas, and the family Cichlidae provides the supreme example of geographically circumscribed vertebrate evolution. The lakes provide a unique comparative series of natural laboratories for evolutionary studies. Primary production is generally high, but in the deeper lakes standing stocks of plankton and of small fish species are low. These pelagic populations are characterised by very high P:B ratios. The fisheries are productive and of socio-economic importance. Large-scale mechanised fishing is not compatible with the survival of the diverse fish communities. Cichlids appear especially vulnerable to unselective fishing. Aquatic reserves might offer a means of survival for at least some communities. Various pollution threats exist. Because water retention times are long, extremely long for some deep lakes, and flushing rates are low, the lakes are vulnerable to pollution which would be long-lasting. Introductions of alien fishes have mostly had undesirable or disastrous results. While the faunas are one of the significant natural heritages of mankind, their conservation must realistically be linked to the legitimate development of the lakes for the well-being of the people who live there. Scientific value alone will not protect the lakes. Just as survival of African terrestrial wildlife in extensive reserves depends heavily upon tourism, so also might the cichlid flocks in underwater reserves. Greater interest from the international scientific community is needed to further rational development and conservation of these great lakes.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00002094
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  • 7
    Electronic Resource
    Electronic Resource
    Unique qualities and special problems of the African Great Lakes (1986)
    Springer
    Environmental biology of fishes 17 (1986), S. 161-183 
    Details
    ISSN: 1573-5133
    Keywords: Meromictic ; Evolution ; Diversity ; Cichlidae ; Productivity ; Aquatic reserves ; Flushing ; Pollution ; Fish introductions ; Lake development ; Limnology ; Fishery management ; Conservation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Synopsis The African Great Lakes consist of large, deep rift valley lakes (e.g. Malawi & Tanganyika) and shallower lakes between the Eastern and Western Rifts (e.g. Victoria). They are a group comparable in size to the North American Great Lakes, but are old. Most are seasonally thermally stratified, and wind is the decisive factor that determines the annual cycle of cooling and mixing. Lakes Tanganyika, Malawi and Kivu are meromictic, with deep relict hypolimnia. Large magnitudes and time scales of periodic internal motion, where these have been measured, appear unique among lakes. These lakes harbour the world's richest lacustrine fish faunas, and the family Cichlidae provides the supreme example of geographically circumscribed vertebrate evolution. The lakes provide a unique comparative series of natural laboratories for evolutionary studies. Primary production is generally high, but in the deeper lakes standing stocks of plankton and of small fish species are low. These pelagic populations are characterised by very high P:B ratios. The fisheries are productive and of socio-economic importance. Large-scale mechanised fishing is not compatible with the survival of the diverse fish communities. Cichlids appear especially vulnerable to unselective fishing. Aquatic reserves might offer a means of survival for at least some communities. Various pollution threats exist. Because water retention times are long, extremely long for some deep lakes, and flushing rates are low, the lakes are vulnerable to pollution which would be long-lasting. Introductions of alien fishes have mostly had undesirable or disastrous results. While the faunas are one of the significant natural heritages of mankind, their conservation must realistically be linked to the legitimate development of the lakes for the well-being of the people who live there. Scientific value alone will not protect the lakes. Just as survival of African terrestrial wildlife in extensive reserves depends heavily upon tourism, so also might the cichlid flocks in underwater reserves. Greater interest from the international scientific community is needed to further rational development and conservation of these great lakes.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00698196
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  • 8
    Electronic Resource
    Electronic Resource
    African lakes and their fishes: conservation scenarios and suggestions (1987)
    Springer
    Environmental biology of fishes 19 (1987), S. 3-26 
    Details
    ISSN: 1573-5133
    Keywords: Captive propagation ; Extinction ; Genetic variability ; Evolution ; Speciation ; Lates niloticus ; Nile perch ; Haplochromines ; Tilapia ; Clupeids ; Oil pollution ; Productivity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Synopsis Man has been associated with a variety of lakes throughout his evolutionary history in Africa. Lakeside dwellers have a close association with and understanding of these lakes. In the past four decades, however, overexploitation, introductions of alien fishes and the possibility of oil pollution present frightening prospects of irreversible losses and massive extinction. The development of scientific understanding of the life support processes, the ecosystems and the rich communities of these lakes has been so outpaced by exploitation and manipulations that accurate predictions regarding the future are impossible. Shallow lakes are more sensitive to physico-chemical changes caused by climatic as well as agricultural and industrial development than deep lakes, but their biotae are endowed with a resilience which facilitates recovery from major depletions to population size. In contrast, the speciose endemic cichlid faunae of deep lakes are sensitive to fishing pressure, are awkward to manage and should be regarded as representing a much smaller resource than initially imagined. The clupeids of Lake Tanganyika can sustain intensive fishing, but their introduction into other natural lakes is not recommended. Enormous changes to native faunae followed the introduction of Lates niloticus to lakes Kyoga and Victoria with dramatic consequences for the fisheries, for the socio-economic status of the region and for the maintenance of biotic diversity. Extinction of almost 300 fish species is a possible further consequence of L. niloticus predation. Intensive selective fishing for L. niloticus is being initiated, but is unlikely to resolve the problem. In the time necessary to substantially reduce L. niloticus, numerous endemic fishes may suffer extinction. A viable alternative to extinction of these species is captive propagation. Conservation of fishes by captive propagation is not a common or well documented practice. To encourage the acceptance of this conservation option a theoretical scenario in which the concepts and protocols are applied to the fishes of Lake Victoria is given. The possibility of returning rescued populations to the lake at a later date, assuming L. niloticus populations have been reduced, is also discussed. It is recommended that captive propagation should be practised to conserve species and to retain the option of returning rescued taxa. Scientists are urged to seek the funding to study tropical ecosystems so that conservation and rational development may acquire a sound foundation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00002733
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  • 9
    Electronic Resource
    Electronic Resource
    Markers of prognosis in breast cancer - the relationship between binding of the lectin HPA and histological grade, SPF, and ploidy (1993)
    Springer
    Breast cancer research and treatment 25 (1993), S. 247-256 
    Details
    ISSN: 1573-7217
    Keywords: breast cancer ; glycosylation ; HPA ; Helix pomatia lectin ; prognosis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Abnormal cellular glycosylation as demonstrated by the binding of a lectin fromHelix pomatia (HPA) to paraffin-embedded sections has been shown in several studies to be associated with aggressive biological behaviour and poor long-term patient prognosis in breast cancer. This study aims to address the possibility that expression of the HPA binding ligand may be of prognostic significance through an association with increased cellular proliferation (as measured by S-phase fraction and histological grade), anaplasia (reflected in histological grade), or ploidy (DNA index). In a 24 year retrospective study, paraffin-embedded sections of 366 primary breast cancers were stained for binding of HPA. All tumours were assessed for histological grade. Flow cytometry was performed on all cases for which sufficient tumour tissue was available (358/366 cases) and S-phase fraction (SPF) and ploidy calculated. Data regarding patient age at diagnosis, nodal status, and tumour size were also recorded. Life table analyses revealed survival advantage for HPA ‘non stainers’ in comparison to ‘stainers’ (p〈 0.001); for patients with tumours of low grade vs. high grade (p〈0.001); and for those with tumours of low SPF vs. high SPF (p〈0.001). No survival advantage was shown for those with diploid vs. aneuploid tumours (p= 0.17). No association was apparent between HPA binding and grade, SPF, or ploidy (Chi squared values not significant). This was confirmed by multivariate analysis in which nodal status, tumour size, and SPF were independently predictive of survival. There was no confounding effect of grade, SPF, or ploidy upon the correlation between survival and HPA binding. HPA was, however, not independently predictive owing to its strong association with nodal status. The results of this study suggest that the prognostic significance of altered glycosylation, as detected by HPA binding, is unlikely to be through an association with proliferative rate, degree of anaplasia, or cellular ploidy, but may rather be through a direct association with the presence of nodal metastases.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00689839
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  • 10
    Electronic Resource
    Electronic Resource
    Glycosylation patterns of the human colon cancer cell line HT-29 detected byHelix pomatia agglutinin and other lectins in culture, in primary tumours and in metastases in SCID mice (1994)
    Springer
    Clinical & experimental metastasis 12 (1994), S. 398-404 
    Details
    ISSN: 1573-7276
    Keywords: colon cancer ; glycosylation ; Helix pomatia agglutinin ; metastasis ; SCID mouse
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Human colonic cancer cells (HT-29, 10 7 cells/dose) were injected subcutaneously between the scapulae of 19 severe combined immunodeficient (SCID) mice. After 19 days, large tumours had developed in 18 out of the 19 animals and the mice were then killed. Metastases were detected in the lungs of 16 animals but not in other organs investigated. Surgical removal of the primary tumour in another group of five animals led to a prolonged survival and further growth of metastases in the lungs. HT-29 injection into the tail vein (n=5)resulted in colonization of the lungs. The tumours that developed in the animals were signet cell carcinomas; these forms are not seen in HT-29 cells in culture. Glycoconjugate expression of the tumours was assessed using several lectins. In many cases the results indicated a stability of lectin-binding patterns from cell culture conditions to implantation into the SCID mice. This was true for the lectin Helix pomatia agglutinin (HPA), the binding of which is associated with a high metastatic potential in some human tumours, including colon cancer. All the primary tumours and metastases were HPA positive. This xenograft tumour model seems to be a clinically relevant system for the study of glycoconjugate expression in human colon cancer cells and their metastases.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01755883
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