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  • 1
    Online Resource
    Online Resource
    The Chromosome Complement. (1968)
    Vienna :Springer Wien,
    Details
    Keywords: Chromosomes. ; Electronic books.
    Type of Medium: Online Resource
    Pages: 1 online resource (211 pages)
    Edition: 1st ed.
    ISBN: 9783709157817
    Series Statement: Protoplasmatologia Cell Biology Monographs ; v.6 / A
    URL: https://ebookcentral.proquest.com/lib/geomar/detail.action?docID=6556902
    DDC: 574.8732
    Language: English
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  • 2
    Online Resource
    Online Resource
    The Chromosome Cycle : Kern- und Zellteilung B the Chromosome Cycle. (1969)
    Vienna :Springer Wien,
    Details
    Keywords: Chromosomes. ; Electronic books.
    Type of Medium: Online Resource
    Pages: 1 online resource (132 pages)
    Edition: 1st ed.
    ISBN: 9783709155905
    Series Statement: Protoplasmatologia Cell Biology Monographs ; v.6 / B
    URL: https://ebookcentral.proquest.com/lib/geomar/detail.action?docID=6556983
    DDC: 574.8732
    Language: English
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  • 3
    Online Resource
    Online Resource
    The Meiotic System. (1965)
    Vienna :Springer Wien,
    Details
    Keywords: Meiosis. ; Electronic books.
    Type of Medium: Online Resource
    Pages: 1 online resource (340 pages)
    Edition: 1st ed.
    ISBN: 9783709157480
    Series Statement: Protoplasmatologia Cell Biology Monographs ; v.6 / F / 1
    URL: https://ebookcentral.proquest.com/lib/geomar/detail.action?docID=6556901
    DDC: 571.845
    Language: English
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  • 4
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    Human junctophilin-2 undergoes a structural rearrangement upon binding PtdIns(3,4,5)P3 and the S101R mutation identified in hypertrophic cardiomyopathy obviates this response (2013)
    Portland Press
    Details
    Publication Date: 2013-11-09
    Description: JP2 (junctophilin-2) is believed to hold the transverse tubular and jSR (junctional sarcoplasmic reticulum) membranes in a precise geometry that facilitates excitation-contraction coupling in cardiomyocytes. We have expressed and purified human JP2 and shown using electron microscopy that the protein forms elongated structures ~15 nm long and 2 nm wide. Employing lipid-binding assays and quartz crystal microbalance with dissipation we have determined that JP2 is selective for PS (phosphatidylserine), with a K d value of ~0.5 μM, with the N-terminal domain mediating this interaction. JP2 also binds PtdIns(3,4,5) P 3 at a different site than PS, resulting in the protein adopting a more flexible conformation; this interaction is modulated by both Ca 2+ and Mg 2+ ions. We show that the S101R mutation identified in patients with hypertrophic cardiomyopathy leads to modification of the protein secondary structure, forming a more flexible molecule with an increased affinity for PS, but does not undergo a structural transition in response to binding PtdIns(3,4,5) P 3 . In conclusion, the present study provides new insights into the structural and lipid-binding properties of JP2 and how the S101R mutation may have an effect upon the stability of the dyad organization with the potential to alter JP2-protein interactions regulating Ca 2+ cycling.
    Print ISSN: 0264-6021
    Electronic ISSN: 0006-2936
    Topics: Biology , Chemistry and Pharmacology
    Published by Portland Press on behalf of The Biochemical Society.
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    PAPER CURRENT
  • 5
    Electronic Resource
    Electronic Resource
    Inter-population sex chromosome polymorphism in the grasshopper Podisma pedestris (1972)
    Springer
    Chromosoma 37 (1972), S. 23-42 
    Details
    ISSN: 1432-0886
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract Populations of the alpine grasshopper Podisma pedestris are either completely XO/XX or else completely neo-XY/neo-XX in character. The neo-XY form is limited in its occurrence to near the extreme southwest edge of the present distribution of the species. Both kinds of population also contain B-chromosomes. These are of two types differing with regard to size, stability and origin. Both types can occur in the same population but have not so far been found in the same individual. The pattern of distribution of the larger, mitotically-stable supernumerary suggests that it might be a remnant X-chromosome which became converted into a B in the initial phase of neo-XY evolution. The smaller, partly unstable supernumerary, on the other hand, may well have originated from a heteromorphic S11 pair also found in some of the populations with small B's. The available evidence points to the neo-XY system having evolved following a secondary movement of the species into the higher ground it now occupies after the climatic amelioration at the end of the last ice age.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00329555
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    Paper (German National Licenses)
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  • 6
    Electronic Resource
    Electronic Resource
    The cytogenetic systems of grasshoppers and locusts (1973)
    Springer
    Chromosoma 44 (1973), S. 123-146 
    Details
    ISSN: 1432-0886
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract Two new cases of supernumerary heterochromatic segments are described. One of these, found in a heterozygous state in eight males of Chorthippus jucundus, is present terminally on the short arm of the longest autosome. The other, present in a single male heterozygote of Trimerotropis tolteca modesta, is again terminally sited, this time on the long arm of the second smallest auto-some. Both segments are considered to be products of tandem duplication rather than translocation. The segment system of C. jucundus, like that of a number of other categories of heterochromatic material, produces a striking increase in mean cell chiasma frequency compared to basic homozygotes from the same population. It is argued that this effect of the segment on recombination provides a potential basis for selection leading to altered fitness. This, in turn, may well have determined the evolution of at least some forms of supernumerary material in natural populations.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00329114
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  • 7
    Electronic Resource
    Electronic Resource
    Causes and consequences of Robertsonian exchange (1975)
    Springer
    Chromosoma 52 (1975), S. 123-136 
    Details
    ISSN: 1432-0886
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract At least two types of Robertsonian exchange are now known in the acrocentric chromosomes of man. Both types involve breakage in the arms adjacent to the centromere. Evidence is presented for a third type of exchange, one involving breakage within the centromere itself, in the grasshopper Percassa rugifrons. In this species, which is regularly homozygous for a single fusion metacentric, the eighteen rod autosomes have small but pronounced granules at the centric end of the chromosome. When C-banded these granules show differential Giemsa staining and appear to represent centromeric chromomeres; these chromomeres are lacking in the metacentric fusion product. Equivalent fusions may have occurred in some mammal species too and possible examples of this are discussed in sheep and mice. The Percassa fusion has led to a modification in both the frequency and the distribution of chiasmata as judged by a comparison of these properties in the metacentric relative to the two next smallest rod equivalents. Comparable modifications are known to occur in other naturally occurring fusions but these changes are certainly not automatic consequences of fusion since they are not shown in at least some newly produced fusion mutants.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00326262
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  • 8
    Electronic Resource
    Electronic Resource
    Myths and mechanisms of meiosis (1976)
    Springer
    Chromosoma 54 (1976), S. 295-325 
    Details
    ISSN: 1432-0886
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract A comparative analysis of the meiotic secquence in a wide variety of organisms indicates there is no convincing evidence that: (1) Premeiotic pairing plays any role in the synapsis of homologues. (2) Heterochromatic association facilitates homologous pairing. (3) Chiasmata ever form within segments which are positively heteropycnotic at zygotenepachytene. (4) Localisation of chiasmata depends on prior localisation of pairing or on the occurrence of euchromatin-heterochromatin boundaries. (5) Prior association of centromeres plays any role in determining co-orientation. (6) Any form of supra-chromosomal organisation exists involving permanent association between the members of a haploid complement, and (7) Unequal progeny ratios recovered from structurally modified Drosophila complements arise as a consequence of distributive pairing. — On the other hand there is good evidence that: (1) Interlocking of bivalents can occur regularly in species with a chiasma frequency sufficiently high to regularly produce ring bivalents and in which the chiasmata are localised to the ends of the bivalent. (2) Some forms of terminal association cannot represent terminalised chiasmata. (3) U-type exchanges present at diplotene result from errors in crossing over. (4) Pairing and chiasma formation are not necessary for coorientation, and (5) at least some types of elastic constrictions present at first metaphase represent extended nucleolar organisers.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00292812
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  • 9
    Electronic Resource
    Electronic Resource
    Cytogenetic components of reproductive isolation in Trimerotropis thalassica and T. occidentalis (1977)
    Springer
    Chromosoma 60 (1977), S. 187-203 
    Details
    ISSN: 1432-0886
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract The grasshopper Trimerotropis thalassica (Bruner) has a diploid count of 2n=23♂ (XO), 24♀ (XX). The two largest autosomes pairs are regularly metacentric, a consequence of fixed pericentric inversions. The X-chromosome is also a fixed metacentric. The remaining nine pairs of autosomes are polymorphic for floating pericentric inversions so that the complement consists of a mixture of telocentric and metacentric members. Trimerotropis occidentalis (Bruner) is polymorphic for comparable inversions in only two of its autosome pairs and has a telocentric X. It is, however, unique among the species of the genus Trimerotropis in having only 21 chromosomes in its male diploid set in all the populations so far studied. A single male found in a mixed population of these two species at Jasper Ridge, Stanford University, was characterised by a count 2n=22♂. In both this respect and in its phenotype it was intermediate in character, representing a natural F1 hybrid between the two species. Cytogenetic analysis of this hybrid male indicated that occidentalis is differentiated from thalassica only in respect of a single tandem translocation. This has involved two of the telocentric elements of thalassica which have fused into a single composite telocentric partly homologous with each of the smaller progenitors. Although potentially capable of forming a multiple of three, one or other of the progenitor chromosomes regularly fails to pair with the tandem product in the hybrid so that one or more univalents invariably occur. These, by lagging, prevent cytokinesis and subsequently lead to the formation of macrospermatids which inevitably produce a measure of sterility. It is argued that this sterility provides a basis for reproductive isolation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00288465
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  • 10
    Electronic Resource
    Electronic Resource
    Heterochromatin variation in Cryptobothrus chrysophorus (1977)
    Springer
    Chromosoma 64 (1977), S. 219-239 
    Details
    ISSN: 1432-0886
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract The endemic grasshopper Cryptobothrus chrysophorus is widely distributed throughout S.E. Australia and its populations display an extensive and spectacular pattern of autosomal variation. While the standard telocentric complement of three long (L1–3), six medium (M4–9) and two short (S10–11) autosome pairs is present throughout most of its range, two quite distinct chromosome “races” can be defined within this species. Populations in the northern part of its distribution (northern N.S.W. and southern Queensland-northern “race”) are differentiated from the remainder (southern “race”) by fixed blocks of distal heterochromatin on autosomes M4, 5, 6, 8 and 9 and by differences in the character of the megameric M7 chromosome. Additionally, while many populations in both races show a polymorphic system of supernumerary segments on the two smallest autosomes (S10–11), that found in the northern “race” is both more variable and more complex. On the other hand all the populations of the southern “race” we have examined are polymorphic for a series of centric shifts which convert telocentrics into acro- or meta-centrics. These occur more commonly in the megameric M7 and the two smallest autosomes (S10–11) although in one population (Forbes Creek, N.S.W.) at least 12 different shifts involving 8 of the autosomes (L3, M4, 5, 6, 7, 8, 9 and S10) are known. By contrast, in the northern “erace” only the small autosomes (S10–11) show centric shifts. These several floating and fixed variants thus involve all chromosomes of the standard set other than the two largest autosomes (L1–2) and the X-chromosome, which appear to be invariate. Finally, morphologically distinct supernumerary (B) chromosomes, intermediate in size between the standard S10 and the M9 elements, are found in both “races” but are especially common in Tasmania, the most southerly point of the species range. These B-chromosomes are partly heterochromatic and partly euchromatic so that they too add to the considerable heterochromatin variation in this species.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00328079
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