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  • 1
    Electronic Resource
    Electronic Resource
    Evolution of the genome size inAkodon (Rodentia, Cricetidae) (1983)
    Springer
    Journal of molecular evolution 19 (1983), S. 362-370 
    Details
    ISSN: 1432-1432
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Nuclear DNA contents were estimated by microdensitometry in five species ofAkodon rodents:Adodon molinae, A. dolores, A. mollis, A. azarae, Bolomys obscurus) and in three chromosomal varieties ofA. molinae (2n=42; 2n=43, 2n=22). The data obtained showed that the species with the highest DNA content wasB. obscurus, followed in order of decreasing genome size byA. molinae, A. mollis, A. dolores andA. azarae. InA. molinae the forms with 2n=42 chromosomes had the lowest and the forms with 2n=44 the highest amount of DNA, while the forms with 2n=43 had intermediate DNA contents. The variation in DNA amount detected inA. molinae was interpreted as a phenomenon of amplification occurring in the chromosomal areas involved in the chromosomal rearrangement giving rise to the polymorphism exhibited by this species. The DNA contents of shared chromosomes (chromosomes with similar size, morphology and G banding pattern, which are found in two or more phylogenetically related species), were compared and correlated with values of total nuclear DNA. The information obtained indicates that: (a) shared chromosomes have variable amounts of DNA: (b) in a given species there is a correlation between the amount of nuclear and chromosomal DNA in most shared chromosomes (and perhaps in most of the chromosmal complement), e.g., the higher the amount of nuclear DNA, the higher the content of DNA in shared chromosomes; (c) some chromosomes may undergo processes of amplification or deletion restricted to certain regions and usually related with mechanisms of chromosomal rearrangements. The data obtained seem to indicate that the genome size of a species depends on the interaction of two independent mechanisms: (1) a general process of DNA variation which acts coincidentally in the same direction (gain or loss) in the whole chromosome complement without disturbing the mechanism of chromosome condensation producing G bands and (2) restricted processes of DNA variations (amplifications or deletions) which act on single chromosomes and which are in most cases related with chromosmal rearrangements.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02101640
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  • 2
    Electronic Resource
    Electronic Resource
    Cytochemical evaluation of sperm and lymphocyte DNA content after treatment with 5N HCl (1986)
    Springer
    Histochemistry and cell biology 84 (1986), S. 41-44 
    Details
    ISSN: 1432-119X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary In situ as well as extra situm cytochemical methods were used to investigate why the observed Feulgen-DNA value of sperm versus lymphocyte cells is lower than expected. After treatment with 5N HCl, in situ experiments involving the GCA reaction and the UV cytophotometry showed the loss of DNA in sperm nuclei to be 12% more than that in lymphocyte nuclei. Extra situm study of sperm and lymphocytes treated with 5N HCl showed the phosphate and DABA contents of sperm to be 35% and 23%, respectively, less than those of lymphocytes. The data suggest that sperm chromatin is much more sensitive than somatic chromatin to HCl depolyrization during the Feulgen reaction, and this can tentatively be attributed to the protein complement of sperm chromatin.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00493418
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  • 3
    Electronic Resource
    Electronic Resource
    Sperm-chromatin maturation in the mouse (1986)
    Springer
    Histochemistry and cell biology 84 (1986), S. 484-491 
    Details
    ISSN: 1432-119X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Cytochemical techniques were used to study chromatin during spermiogenesis and sperm maturation in the mouse, starting from the stages at which the substitution of somatic histones by testis-specific proteins occurs. It was possible to distinguish and analyze the different temporal incidence of two processes involved in sperm maturation, i.e. chromatin condensation (a tridimensional highly compacted arrangement) and chromatin stabilization (a tough structure, which protects the genome DNA). The first process, involving a reduction in the nuclear size and a decrease in the amount of sperm DNA accessible to specific cytochemical reactions and stainings, was found to reach its maximum in caput-epididymidis spermatozoa, in which electron microscopy revealed that the sheared chromatin was mainly organized into 120-Å-thick knobby fibers. No further changes were found in sperm up to their appearance in the fallopian tubes. On the contrary, chromatin stabilization, the onset of which occurs in the testis (at the late spermatid stage) via the formation of -S−S- cross-links, is completed in the vas deferens, where chromatin has a superstructure consisting of thicker fibers, with diameters of 210 and 350 Å. The reductive cleavage of disulfides in vas-deferens spermatozoa does not completely destroy the superstructure of sperm chromatin, which could indicate ‘coiling’ of the basic knobby fiber. In fact, when the ion concentration was increased, the chromatin of vas-deferens spermatozoa appeared to be organized into fibers with diameters similar to those of the caput epididymidis. This unique organization of mature sperm chromatin should have an essential role in the fast swelling of spermatozoa during fertilization.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00482981
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  • 4
    Electronic Resource
    Electronic Resource
    Pericentromeric heterochromatin and A-T contents during Robertsonian fusion in the house mouse (1986)
    Springer
    Chromosoma 94 (1986), S. 31-35 
    Details
    ISSN: 1432-0886
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract The pericentromeric heterochromatin of meiotic trivalents formed by the Robertsonian (Rb) chromosomes and the two homologous acrocentrics in the house mouse was evaluated by static cytophotometry after selective staining. To reveal pericentromeric heterochromatin specifically, C-banding Giemsa and Hoechst 33258 stains were utilized. Five different Rb chromosomes were investigated and none of them possessed less pericentromeric heterochromatin than the sum of the two homologous acrocentrics. Moreover the total A-T (DAPI) and DNA (PI) content was quantitatively evaluated, by flow cytometry, in G0/G1 nuclei belonging to four different Rb mouse populations, karyotypically characterized by the presence of up to nine Rb chromosomes. Again there were no significant difference, of DAPI and PI content, in the Rb populations nor between any of them and the NMRI/HAN strain with forty aerocentric chromosomes. We conclude that the main consequence of Robertsonian processes (i.e. the rapid variation of the karyotype structure) does not imply detectable quantitative variation in the genome portion involved in the Rb process. We also discuss the possibility that the high rate of Rb exchange in the house mouse could be favoured by the simultaneous effects of undetectable losses of chromosomal material, high repetitiveness of the DNA involved, the presence of the same major type of satellite DNA over each chromosome and the all acrocentric constitution of the karyotype.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00293527
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  • 5
    Electronic Resource
    Electronic Resource
    Differences in the organization and chromosomal allocation of satellite DNA between the European long tailed house miceMus domesticus andMus musculus (1990)
    Springer
    Chromosoma 99 (1990), S. 11-17 
    Details
    ISSN: 1432-0886
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract We compared the organization of satellite DNA (stDNA) and its chromosomal allocation inMus domesticus and inMus musculus. The two stDNAs show similar restriction fragment profiles after digestion (probed withM. domesticus stDNA) with some endonucleases of which restriction sequences are present in the 230–240 bp repetitive unit of theM. domesticus stDNA. In contrast, EcoRI digestion reveals thatM. musculus stDNA lacks most of the GAATTC restriction sites, particularly at the level of the half-monomer. The chromosome distribution of stDNA (revealed by anM. domesticus stDNA probe) shows different patterns in theM. domesticus andM. musculus karyotypes, with about 60% ofM. domesticus stDNA retained in theM. musculus genome. It is particularly noteworthy that the pericentromeric regions ofM. musculus chromosomes 1 and X are totally devoid ofM. domesticus stDNA sequences. In both groups, the differences in energy transfer between the stDNA-bound fluorochromes Hoechst 33258 and propidium iodide suggest that AT-rich repeated sequences have a much more clustered array in theM. domesticus stDNA, as if they are organized in tandem repeats longer than those ofM. musculus. Considering the data as a whole, it seems likely that the evolutionary paths of the two stDNAs diverged after the generation of the ancestral 230–240 bp stDNA repetitive unit through the amplification, in theM. domesticus genome, of a family repeat which included the EcoRI GAATTC restriction sequence.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01737284
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  • 6
    Electronic Resource
    Electronic Resource
    Quantitative aspects of the cytochemical Feulgen-DNA procedure studied on model systems and cell nuclei (1980)
    Springer
    Histochemistry and cell biology 69 (1980), S. 1-17 
    Details
    ISSN: 1432-119X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Quantitative aspects of DNA losses during fixation and pararosaniline(SO2)-Feulgen staining of microscopic preparations were studied. The preparation of a new cytochemical model, consisting of DNA-protein layers (with thicknesses between 0.1 and 5.0 μm) on microscopic glass slides is described and potentialities and limitations of this model are discussed. Polyacrylamide films into which high molecular weight calf thymus DNA or chicken erythrocyte nuclei had been constrained served as another model. As biological objects chicken erythrocyte nuclei and rat liver nuclei either in suspension or on microscopical glass slides were used. The experimental results indicate a loss of about 5% of the DNA due to the fixation procedure applied. Hydrolysis in 5 N HCl at room temperature, staining with the pararosaniline-Schiff medium and rinsing with sulfurous acid induced losses of DNA too, varying in amount depending on the type of preparation used. About 10% of the original DNA content is lost in total from chicken erythrocyte nuclei and rat liver nuclei dried on microscopical glass slides, from chicken erythrocyte nuclei constrained in polyacrylamide films, and from DNA-protein layers on microscopic glass slides. For nuclei fixed and stained in suspension the total losses amount to about 40%. The differences in losses between various types of preparations are discussed. Biochemically, the content of DNA originally present per chicken eythrocyte nucleus was determined to be 2.52 pg, a value, which is in good accordance with reliable biochemical data published already. It is shown that calibration of cytochemical staining intensities into biochemical units or absolute amounts of material by use of a model system, is only reliable when it is known or to be expected that both the loss of material due to fixation and staining, and the stoichiometric relation between material present and dye molecules is identical. The same holds for the application of internal biological reference systems.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00508362
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  • 7
    Electronic Resource
    Electronic Resource
    Feulgen-DNA amounts and karyotype lengths of three planarian species of the genusDugesia (1986)
    Springer
    Cellular and molecular life sciences 42 (1986), S. 75-77 
    Details
    ISSN: 1420-9071
    Keywords: Cytotaxonomy ; genome size ; karyotype length ; nuclear DNA amount ; planarians
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Genome sizes of the planariansD. lugubris (2n=8),D. polychroa (2n=8) andD. benazzii (2n=16) were evaluated on metaphase plates by measuring both the Feulgen-DNA contents and the karyotype lengths. In the three species, genome sizes are significantly different; this finding rules out the possibility of a karyotype evolution through simple chromosome rearrangements betweenD. lugubris andD. polychroa. A different Feulgen-DNA content per unit length of karyotype in the three species studied was also found, which suggests that DNA could be differently packed along metaphase chromosomes.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01975903
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  • 8
    Electronic Resource
    Electronic Resource
    Macrobiotus pseudohufelandi Iharos as a model for cytotaxonomic study in populations of eutardigrades (Tardigrada) (1987)
    Springer
    Cellular and molecular life sciences 43 (1987), S. 210-213 
    Details
    ISSN: 1420-9071
    Keywords: Cytotaxonomy ; genome size ; Tardigrada ; Macrobiotus
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The morphotype, chromosome number and Feulgen-DNA content of bisexual and unisexual populations ofMacrobiotus pseudohufelandi were examined. Individuals of unisexual populations were triploid with ameiotic parthenogenesis. Their lowest Feulgen-DNA content is about three-fold that of sperm from a bisexual population. Egg shell shape also differs in the two types of population. However, the highest Feulgen-DNA content was the same (24 A.U.) in both diploid and triploid animals.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01942857
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  • 9
    Electronic Resource
    Electronic Resource
    Spermatozoa of chromosomally heterozygous mice and their fate in male and female genital tracts (1984)
    New York, NY : Wiley-Blackwell
    Gamete Research 9 (1984), S. 273-286 
    Details
    ISSN: 0148-7280
    Keywords: mouse spermatozoa ; Robertsonian chromosomes ; DNA content ; sperm aneuploidy ; genital tracts ; prezygotic selection ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: The fate of morphologically normal but chromosomally abnormal spermatozoa derived from mice with variable degrees and complexity of Robertsonian heterozygosity was studied at different sites along the male and female genital tract by Feulgen-DNA measurements. In addition, the percentage frequencies of morphologically abnormal spermatozoa in transit along the male and female genital tracts were studied.It was found that during transit from the epididymis to the vas deferens the distribution of the Feulgen-DNA contents of morphologically normal spermatozoa changed: Spermatozoa with chromatin with the extremely low or high Feulgen staining intensity disappeared. The percentages of morphologically abnormal sperm cells did not change at these levels. In the female genital tracts, the distribution of Feulgen-DNA content of morphologically normal spermatozoa did not show significant changes. This indicates that spermatozoa are able to reach the fallopian tube in spite of gross genome unbalance. There is evidence that unbalanced spermatozoa take part in the fertilization process, producing abnormal zygotes subject to postzygotic loss. Conversely morphologically abnormal spermatozoa were preferentially lost before they reached the fallopian tube, suggesting they had been eliminated prezygotically.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/mrd.1120090305
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  • 10
    Electronic Resource
    Electronic Resource
    Protamine amount and cross linking in mouse teratospermatozoa and aneuploid spermatozoa (1990)
    New York, NY [u.a.] : Wiley-Blackwell
    Molecular Reproduction and Development 25 (1990), S. 297-301 
    Details
    ISSN: 1040-452X
    Keywords: Chromosome mutations ; Mutations ; Spermatozoa ; Mouse protamine ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: The level of SH-group oxidation in spermatozoa from the cauda epididymis was measured by a cytofluorometric method in chromosomally normal mice and two chromosome mutants. The first one, a tertiary trisomic karyotype (Ts(113)7OH), is characterized by severe oligospermia and high levels (≈75%) of malformed spermatozoa. The second, a hybrid between two European feral mouse stocks, is heterozygous for multiple Robertsonian translocations and produces exclusively aneuploid spermatozoa. Neither the severe teratospemiogenesis nor the severe aneuploidy was reflected in total SH-group fluorescence values nor in free SH-group fluorescence. It is concluded that both the production of protamines and protamine cross linking by S-S bridge formation are rather autonomous processes during spermatogenesis because (1) the increased DNA variance of the aneuploid spermatozoa is not reflected in an increased variance of the total and free SH-groups, (2) aneuploidy for the protamine gene carrying chromosome 16 is not reflected by the SH-group values for individual spermatozoa, and (3) protamine production and cross linking are independent of the mild to severe terataspermiogenesis in the tertiary trisomic karyotype.
    Additional Material: 2 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/mrd.1080250312
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