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  • Cell & Developmental Biology  (29)
  • Polymer and Materials Science  (26)
  • Senescence  (7)
  • 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
    Heterokaryotic transmission of senescence plasmid DNA in Neurospora (1990)
    Springer
    Current genetics 17 (1990), S. 139-145 
    Details
    ISSN: 1432-0983
    Keywords: Neurospora ; Senescence ; Plasmids ; Mitochondrial DNA ; Heterokaryons
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Heterokaryotic transmission is one of the major techniques for the study of cytoplasmic inheritance and here we have applied it to the senescence-determining plasmids kalilo (Hawaiian) and maranhar (Indian). We have shown that kalilo-based senescence is effectively transmitted by cytoplasmic contact, both in N. crassa and in N. intermedia. In the first place, the heterokaryons themselves are senescent, confirming the suppressivity of the senescence phenotype in mixtures of normal and senescent cytoplasms. Second, senescence is found in new nuclear associations, as shown by analysis of conidial isolates and meiocytes stemming from the heterokaryons. In addition, the free plasmid AR-kalDNA, and its form that is inserted into mtDNA, (mtIS-kalDNA), are both transmitted to new nuclear associations. In a transient fusion between senescent N. intermedia and nonsenescent N. crassa cells, AR-kalDNA was transmitted to N. crassa and mtIS-kalDNA was transmitted to N. crassa mtDNA. A cryptic mitochondrial plasmid, not associated with senescence, was also transmitted very efficiently to N. crassa mitochondria. In mixed kalilo/maranhar fusions, both plasmids coexisted, approximately equally, in the heterokaryons themselves, and in conidial isolates. However, in sexual derivatives, AR-marDNA was in an excess and AR-kalDNA was sometimes absent. The efficient heterokaryotic transmission of these elements suggests that this is one of their natural modes of spread in populations.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00312859
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  • 3
    Electronic Resource
    Electronic Resource
    A kalilo-like linear plasmid in Louisiana field isolates of the pseudohomothallic fungus Neurospora tetrasperma (1994)
    Springer
    Current genetics 26 (1994), S. 336-343 
    Details
    ISSN: 1432-0983
    Keywords: Kalilo ; Plasmid ; Senescence ; Neurospora
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Two Louisiana strains of Neurospora tetrasperma contain a linear plasmid (LA-kalDNA) with a restriction map identical to the Hawaiian Neurospora intermedia senescence plasmid, kalDNA, but with termini 100 nucleotide pairs shorter. One of these strains also bore a circular plasmid similar to the Hawaiian circular plasmid Hanalei-2. One species probably acquired both plasmids from the other by horizontal transfer, at a time sufficiently distant for sequence divergence to take place. Many LA-kalDNA-bearing derivative strains senesced, but this plasmid does not guarantee senescence. Furthermore, LA-kalDNA does not insert into mtDNA. One senescent strain showed no LA-kalDNA. The plasmids are effectively transmitted via the pseudohomothallic sexual cycle. Single mating-type derivatives transmit plasmids maternally.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00310498
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  • 4
    Electronic Resource
    Electronic Resource
    The dynamics of mitochondrial plasmids in a Hawaiian population of Neurospora intermedia (1995)
    Springer
    Current genetics 29 (1995), S. 44-49 
    Details
    ISSN: 1432-0983
    Keywords: Mitochondrial plasmids ; Senescence ; Neurospora ; Meiotic transmission
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract We analysed the distribution of mitochondrial plasmids among 82 Neurospora intermedia isolates from Hawaii; 74% of the isolates carried the neutral circular plasmid Han-2, whereas 38% contained the linear senescence-causing plasmid kalDNA. The distributions of the two plasmids are independent. There is no significant difference between the Kauaian population of 1972 and that of 1976. To further examine the reasons for this frequency distribution we studied the transmission of both Hawaiian plasmids through the maternal parent in a large series of crosses using non-Kalilo isolates as conidial parents. Plasmids can be lost during the sexual cycle. The Han-2 plasmid is transmitted more efficiently than kalDNA. No clear cases of autonomous or non-autonomous plasmid suppression were observed, so loss can be considered accidental. One Kalilo strain proved to be ineffectual as a maternal parent, and this reduced its ability to transmit kalDNA to the next generation. The dynamic balance of plasmids in natural populations over time is probably a result of the interplay of many forces, including those described in this work and those from several other studies on Neurospora plasmids.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00313192
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  • 5
    Electronic Resource
    Electronic Resource
    Suppression of cytoplasmic senescence in Neurospora (1992)
    Springer
    Current genetics 21 (1992), S. 479-484 
    Details
    ISSN: 1432-0983
    Keywords: Neurospora ; Senescence ; Plasmid ; Suppressor
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary We have shown that senescence in Kalilo strains of Neurospora, caused by a linear mitochondrial plasmid called kalDNA, is suppressible by existing variants of the nuclear genome. The suppressors are manifested by 4:4 segregation of senescence and immortality in asci from crosses between senescent female strains and males chosen from non-senescent candidate stocks. In one case of suppression, the asci also show segregation at the plasmid level. There is a reduction of kalDNA to barely detectable levels in the four ascospores showing immortality, so this suppressor evidently influences the maintenance of the plasmid itself. In the other case of suppression, the phenotypic segregation is not correlated with segregation at the plasmid level, and all eight ascospores in the asci show both free and inserted forms of kalDNA. This suggests that the suppression genotype provides a way of tolerating the presence of the plasmid rather than diminishing it. However, the allele f, which provides an analogous kind of suppression for the cytoplasmic mutation poky, does not suppress Kalilo or Maranhar senescence. Suppression is hence shown to be a possible option for host strains to combat the plasmid in nature, but no examples of suppressors were found in a limited survey of natural isolates. In addition, we have shown that long-lived, presumably non-senescent, strains do not arise by suppressor mutation, but lose senescence plasmid DNA by another mechanism.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00351658
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  • 6
    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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  • 7
    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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  • 8
    Electronic Resource
    Electronic Resource
    Architectural regularity of the subepidermal reticulum of fibers in the adult newt, Triturus viridescens (Diemictylus v.)This investigation was supported in part by an institutional grant from the American Cancer Society, Inc., and in part by a Public Health Service research grant, RG-36208 (R1), from the National Institutes of Health. (1962)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 111 (1962), S. 275-285 
    Details
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jmor.1051110305
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  • 9
    Electronic Resource
    Electronic Resource
    The sudanophilic lipid of normal and regenerating limb tissues of the adult newt, Diemictylus viridescensThis investigation was supported by a Public Health Service research grant GM06208 from the National Institute of General Medical Sciences. (1966)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 118 (1966), S. 57-77 
    Details
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The most intense and widely distributed sudanophilic responses of cryostat-sectioned newt limb tissues were obtained with a simultaneous fix and stain procedure of 1:1 10% formal-calcium and sudan black B. Droplets and globules of lipid mixtures and rodlets (mitochondria) were typical responses distributed within the epidermis, subcutaneous glands, dermis and other connective tissues, striated muscle (also with positive fibrils), tunics of blood vessels, and blood cells. A prominent droplet response was located subjacent to the adepidermal basement membrane. The myelin of brachial nerve stained intensely.In regenerating limbs, the wound epithelium response was comparable to that of epidermis. Post-amputational lipophanerosis of injured muscle and brachial nerves was observed. The retrograde degeneration of nerve myelin was extensive, and continued into the early differentiative phase of regeneration. Lipid-engorged macrophages were prominent among the injured tissues, distal to these, and within the wound epithelium.The regeneration blastema revealed a large quantity of sudanophilic lipid. Prominent droplet and rodlet responses were typical of the myelinating regenerating nerves. The response of regenerating muscle equaled that of the mature stump fibers. The cells of the regenerating chondroskeleton contained sudanophilic lipid.Organic solvents such as acetone, ether, chloroform and chloroform:methanol reduced or prevented the sudanophilic responses. Sudan red 7B revealed less lipid than did sudan black B. A fixation effect was demonstrated with post-chromated formalcalcium, and chromic-formalin fixed sections. In the latter preparations, swollen-bodies, identified as mitochondria, stained intensely.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jmor.1051180105
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  • 10
    Electronic Resource
    Electronic Resource
    Tolerance, limb regeneration and collagen fibrogenesis under high oxygen concentrations by the adult newt, Diemictylus viridescensThis investigation was supported by a grant from the University of Illinois Research Board. (1971)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 133 (1971), S. 167-178 
    Details
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Adult newts placed in an atmospheric environment of 85% oxygen, saturated humidity, and at a temperature of 20 ± 1°C survived particularly well a 44-day test period. They did not succumb to “oxygen toxicity” as has been frequently reported for other vertebrate species.Having established the newt's tolerance of high oxygen atmosphere, the effect of oxygen on growth and development in the regenerating newt limb was investigated. Under the atmospheric conditions described above, and under 92% oxygen, the regeneration of adult newt limbs appeared to be retarded during the first 25 days after amputation when compared with regenerating limbs of control animals kept under a normal atmosphere of 21% oxygen (air). Thereafter, little or no difference could be discerned between the regeneration of experimental and control limbs.It is known that molecular oxygen participates directly in the hydroxylation of proline to hydroxyproline in the synthesis of collagen. Sectioned regenerates stained specifically for collagen were examined to determine if collagen synthesis was induced in experimental animals. Two regeneration-inhibited limbs of oxygenated newts showed cicatrical repair of the apical limb stump 25 days after amputation. However, the majority of the experimental animals revealed no obvious increase in collagen fibers.These results contraindicate any marked “oxygen toxicity” affecting the life of the newts, or regeneration of their limbs. It is suggested that a change in collagen fiber type might have been induced by the high-oxygen atmosphere. Investigations to test this hypothesis are currently underway.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jmor.1051330204
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