scholarly journals The Abdominal Epidermis of Calliphora Erythrocephala (Diptera)

1974 ◽  
Vol 16 (1) ◽  
pp. 113-131 ◽  
Author(s):  
M. J. PEARSON
Keyword(s):  
Dna Synthesis ◽  
Nuclear Dna ◽  
Larval Growth ◽  
Polytene Chromosomes ◽  
Sense Organs ◽  
Calliphora Erythrocephala ◽  
Functional Correlation ◽  
2C Dna Content ◽  
Polytene Nuclei ◽  
Giant Chromosome

The extremely rapid growth of feeding larvae of Calliphora is achieved with a hypertrophy of larval epidermal cells and concomitant polytene specialization of their nuclei. Within the epidermis of each abdominal segment are differentiated sense organs of the campaniform and a more complex - possibly chemosensory - kind in a constant pattern; there is no post-embryonic differentiation of new sense organs before metamorphosis, while the cuticle-secreting cell of these sense organs also becomes polytene. The polytene organization of epidermal nuclei differs from the classical giant chromosome structures of lower dipteran larval cells. Calliphora epidermal polytene chromosomes irregularly fragment into oligotene or smaller fibrils which, through apparently non-specific reassociations, form a nuclear reticulum of which the banded polytene regions are a part. This loose reticular organization is unlikely to reflect a condition of genetic activity. Photometric densitometry shows the period of polytene DNA replication in general epidermal nuclei is closely correlated with the period of larval growth. At hatching, epidermal nuclei are diploid, with the 2C DNA content. Through a series of endoreduplications, such that at any stage nuclei tend to fall into a series of DNA classes with a percentage falling in between, the largest polytene nuclei reach about 256C by the end of the feeding stage. During the feeding stage, whole mount autoradiography shows a very slow continuation of DNA synthesis in some epidermal nuclei; that is, after cessation of larval growth. DNA synthesis in cupologen nuclei of the campaniform organs ceases after secretion of the third instar cuticle at the end of the second instar. The polytene cycle responsible for nuclear DNA increase is discussed in the context of these data, and a functional correlation drawn for the rate of polytene increase in the epidermal nuclei and the cupologen nuclei. This correlation suggests active control of the cycle, and raises the question of the significance of the polytene cell cycle.

scholarly journals Involvement of deoxyribonucleic acid polymerase β in nuclear deoxyribonucleic acid synthesis

1978 ◽  
Vol 173 (1) ◽  
pp. 309-314 ◽  
Author(s):  
T R Butt ◽  
W M Wood ◽  
E L McKay ◽  
R L P Adams
Keyword(s):  
Dna Synthesis ◽  
Dna Polymerase ◽  
Deoxyribonucleic Acid ◽  
Nuclear Dna ◽  
Dna Polymerase Beta ◽  
Cell Nuclei ◽  
High Molecular Weight Dna ◽  
Dna Polymerase Alpha ◽  
Polymerase Beta

The effects on DNA synthesis in vitro in mouse L929-cell nuclei of differential extraction of DNA polymerases alpha and beta were studied. Removal of all measurable DNA polymerase alpha and 20% of DNA polymerase beta leads to a 40% fall in the replicative DNA synthesis. Removal of 70% of DNA polymerase beta inhibits replicative synthesis by 80%. In all cases the nuclear DNA synthesis is sensitive to N-ethylmaleimide and aCTP (arabinosylcytosine triphosphate), though less so than DNA polymerase alpha. Addition of deoxyribonuclease I to the nuclear incubation leads to synthesis of high-molecular-weight DNA in a repair reaction. This occurs equally in nuclei from non-growing or S-phase cells. The former nuclei lack DNA polymerase alpha and the reaction reflects the sensitivity of DNA polymerase beta to inhibiton by N-ethylmaleimide and aCTP.

IN VIVO SYNTHESIS AND BREAKDOWN OF DEOXYRIBONUCLEIC ACID IN TRIBOLIUM CONFUSUM DUVAL

1966 ◽  
Vol 44 (12) ◽  
pp. 1571-1575 ◽  
Author(s):  
K. D. Chaudhary ◽  
A. Lemonde
Keyword(s):  
Dna Synthesis ◽  
Growth Phase ◽  
Deoxyribonucleic Acid ◽  
Total Concentration ◽  
Larval Growth ◽  
Pupal Stage ◽  
Larval Period ◽  
Tribolium Confusum ◽  
In Vivo Synthesis

The in vivo synthesis of deoxyribonucleic acid (DNA), as shown by the rate of incorporation of14C-thymidine, has been investigated at different stages in the life cycle of Tribolium confusum. During the larval period, a close similarity is observed between the rate of DNA synthesis and the pattern of growth. The pupal stage, which is a non-growth phase, is characterized by a cessation of DNA synthesis. During the larval growth phase, although the 3-day-old larvae have the lowest and the 13-day-old have the highest rate of DNA synthesis, the rate of DNA degradation in the older larvae is almost twice as great as that of the younger larvae. These findings are consistent with the observed total concentration of DNA of the insect at these stages.

Continuous DNA replication in the nucleus of the dinoflagellate Prorocentrum micans (Ehrenberg)

1977 ◽  
Vol 27 (1) ◽  
pp. 81-90
Author(s):  
S.A. Filfilan ◽  
D.C. Sigee
Keyword(s):  
Electron Microscope ◽  
Dna Synthesis ◽  
Nuclear Dna ◽  
Continuous Process ◽  
Prorocentrum Micans ◽  
Interphase Nuclei ◽  
Electron Microscope Autoradiography ◽  
Dividing Cells ◽  
High Degree ◽  
Very High

The uptake of tritiated thymine into cells of a heterogeneous population of Prorocentrum micans was investigated using light-microscope and electron-microscope autoradiography. Specificity of thymine uptake into DNA was demonstrated by the specific removal of label from wax-embedded material using DNase and by the high degree of localization of nuclear label to chromosomes in the electron-microscope autoradiographs. All nuclei, including both dividing and non-dividing cells, showed a substantial uptake of label, indicating that nuclear DNA synthesis in Prorocentrum micans is a continuous process. The level of DNA synthesis does show considerable variation, however, with very high levels in some interphase nuclei. The continuous replication of nuclear DNA provides further evidence of dinoflagellate affinity to the prokaryotes, and indicates that Prorocentrum micans is a very primitive eukaryote cell.

scholarly journals Meiotic DNA synthesis during mouse spermatogenesis.

1975 ◽  
Vol 64 (1) ◽  
pp. 211-222 ◽  
Author(s):  
M L Meistrich ◽  
B O Reid ◽  
W J Barcellona
Keyword(s):  
Dna Synthesis ◽  
Nuclear Dna ◽  
Sodium Dodecyl ◽  
Phenol Extraction ◽  
Sperm Dna ◽  
Sperm Nuclei ◽  
Cauda Epididymidis ◽  
Contamination Levels ◽  
Triton X ◽  
Mechanical Shearing

The incorporation of radioactivity into various cells in the sequence of spermatogenesis was measured by preparing highly purified spermatozoan nuclei from the cauda epididymidis of mice at daily intervals after injection of (3H)thymidine. The stages of differentiation of these sperm at the time of thymidine administration were calculated from the kinetics of spermatogenesis. The procedure for purification of sperm nuclei included sonication, mechanical shearing, and treatment with trypsin, DNase, Triton X-100, 2M NaC1, and sodium dodecyl sulfate. DNA was isolated from these nuclei by treatment with dithiothreitol and pronase, followed by phenol extraction and ethanol precipitation. The levels of radioactivity in the epididymal sperm head preparations were low (less than 13 dpm/mouse) for 27 days after injection, and then rose dramatically to over 4 times 104 dpm/mouse. Further experiments demonstrated that the 11 dpm of 3H radioactivity contained in sperm heads at 21 or 26 days after injection of (3H)TdR was significantly above background and contamination levels from other cells or other sources. Most of the radioactivity was in the sperm DNA and represented incorporation of tritium from (3H)TdR into the nuclear DNA of meiotic cells at 0.002 percent of the rate of incorporation into S-phase cells. Little, if any, (3H)TdR was incorporation into the DNA of spermatids. The levels of DNA synthesis during the meiotic prophase in the mouse appear to be much lower than those reported for other organisms.

scholarly journals Miscanthus: Inter- and Intraspecific Genome Size Variation Among M. × Giganteus, M. Sinensis, M. Sacchariflorus Accessions

2015 ◽  
Vol 57 (1) ◽  
pp. 104-113
Author(s):  
Sandra Cichorz ◽  
Maria Gośka ◽  
Monika Rewers
Keyword(s):  
Genome Size ◽  
Dna Content ◽  
Nuclear Dna ◽  
Size Variation ◽  
Nuclear Dna Content ◽  
Interspecific Variation ◽  
Genome Size Variation ◽  
2C Dna Content ◽  
Cytological Characteristics ◽  
Stomatal Length

AbstractSinceM. sinensisAnderss.,M. sacchariflorus(Maxim.) Hack. andM. ×giganteusJ.M.Greef & Deuter ex Hodk. and Renvoize have considerably the highest potential for biomass production amongMiscanthusAnderss. species, there is an urgent need to broaden the knowledge about cytological characteristics required for their improvement. In this study our objectives were to assess the genome size variation among eighteenMiscanthusaccessions, as well as estimation of the monoploid genome size (2C and Cx) of theM. sinensiscultivars, which have not been analyzed yet. The characterization of threeMiscanthusspecies was performed with the use of flow cytometry and analysis of the stomatal length. The triploid (2n = 3x = 57)M. sinensis‘Goliath’ andM. ×giganteusclones possessed the highest 2C DNA content (8.34 pg and 7.43 pg, respectively). The intermediate 2C-values were found in the nuclei of the diploid (2n = 2x = 38)M. sinensisaccessions (5.52–5.72 pg), whereas they were the lowest in the diploid (2n = 2x = 38)M. sacchariflorusecotypes (4.58–4.59 pg). The presented study revealed interspecific variation of nuclear DNA content (P<0.01) and therefore allowed for recognition of particular taxa, inter- and intraspecific hybrids and prediction of potential parental components. Moreover, intraspecific genome size variation (P<0.01) was observed inM. sinensiscultivars at 3.62%. The values of the stomatal size obtained for the triploidM. ×giganteus‘Great Britain’ (mean 30.70 μm) or ‘Canada’ (mean 29.67 μm) and diploidM. sinensis‘Graziella’ (mean 29.96 μm) did not differ significantly, therefore this parameter is not recommended for ploidy estimation.

scholarly journals Interaction between the DrosophilaCAF-1 and ASF1 Chromatin Assembly Factors

2001 ◽  
Vol 21 (19) ◽  
pp. 6574-6584 ◽  
Author(s):  
Jessica K. Tyler ◽  
Kimberly A. Collins ◽  
Jayashree Prasad-Sinha ◽  
Elizabeth Amiott ◽  
Michael Bulger ◽  
...  
Keyword(s):  
Dna Synthesis ◽  
Polytene Chromosomes ◽  
Normal Growth ◽  
Chromatin Assembly ◽  
Truncated Form ◽  
Assembly Factor ◽  
Development And Differentiation ◽  
Growth Development

ABSTRACT The assembly of newly synthesized DNA into chromatin is essential for normal growth, development, and differentiation. To gain a better understanding of the assembly of chromatin during DNA synthesis, we identified, cloned, and characterized the 180- and 105-kDa polypeptides of Drosophila chromatin assembly factor 1 (dCAF-1). The purified recombinant p180+p105+p55 dCAF-1 complex is active for DNA replication-coupled chromatin assembly. Furthermore, we have established that the putative 75-kDa polypeptide of dCAF-1 is a C-terminally truncated form of p105 that does not coexist in dCAF-1 complexes containing the p105 subunit. The analysis of native and recombinant dCAF-1 revealed an interaction between dCAF-1 and theDrosophila anti-silencing function 1 (dASF1) component of replication-coupling assembly factor (RCAF). The binding of dASF1 to dCAF-1 is mediated through the p105 subunit of dCAF-1. Consistent with the interaction between dCAF-1 p105 and dASF1 in vitro, we observed that dASF1 and dCAF-1 p105 colocalized in vivo inDrosophila polytene chromosomes. This interaction between dCAF-1 and dASF1 may be a key component of the functional synergy observed between RCAF and dCAF-1 during the assembly of newly synthesized DNA into chromatin.

Nuclear DNA synthesis is blocked by UV irradiation in dictyostelium discoideum

1989 ◽  
Vol 217 (1) ◽  
pp. 25-32 ◽  
Author(s):  
David L Hurley ◽  
Andrea M Skantarz ◽  
Reginald A Deering
Keyword(s):  
Dna Synthesis ◽  
Dictyostelium Discoideum ◽  
Uv Irradiation ◽  
Nuclear Dna

The endocycle controls nurse cell polytene chromosome structure during Drosophila oogenesis

Development ◽  
1999 ◽  
Vol 126 (2) ◽  
pp. 293-303 ◽  
Author(s):  
K.J. Dej ◽  
A.C. Spradling
Keyword(s):  
Polytene Chromosome ◽  
Nurse Cell ◽  
Chromosome Structure ◽  
Polytene Chromosomes ◽  
S Phase ◽  
Nurse Cells ◽  
Chromosome Behavior ◽  
M Phase ◽  
Diploid Cells ◽  
Polytene Nuclei

Polytene chromosomes exhibit intricate higher order chromatin structure that is easily visualized due to their precisely aligned component strands. However, it remains unclear if the same factors determine chromatin organization in polyploid and diploid cells. We have analyzed one such factor, the cell cycle, by studying changes in Drosophila nurse cell chromosomes throughout the 10 to 12 endocycles of oogenesis. We find that nurse cells undergo three distinct types of endocycle whose parameters are correlated with chromosome behavior. The first four endocycles support complete DNA replication; poorly banded polytene euchromatin progressively condenses during the late S phases to produce blob-like chromosomes. During the unique fifth endocycle, an incomplete late S phase is followed by a mitosis-like state during which the 64C chromosomes dissociate into 32 chromatid pairs held together by unreplicated regions. All the subsequent endocycles lack any late S phase; during these cycles a new polytene chromosome grows from each 2C chromatid pair to generate 32-ploid polytene nuclei. These observations suggest that euchromatin begins to condense during late S phase and that nurse cell polytene chromosome structure is controlled by regulating whether events characteristic of late S and M phase are incorporated or skipped within a given endocycle.

Electron-Microscopic Observations on the Macronuclear Development of Stylonychia Mytilus and Tetrahymena Pyriformis (Ciliophora-Protozoa)

1973 ◽  
Vol 13 (2) ◽  
pp. 479-509 ◽  
Author(s):  
K. G. MURTI
Keyword(s):  
Dna Synthesis ◽  
Nuclear Membrane ◽  
Fibrous Material ◽  
Structural Changes ◽  
Degradation Products ◽  
Polytene Chromosomes ◽  
Tetrahymena Pyriformis ◽  
Nucleotide Sequences ◽  
Macronuclear Development ◽  
Stylonychia Mytilus

This report describes an ultrastructural investigation of macronuclear development following conjugation in Stylonychia mytilus (a spirotrichous ciliate) and Tetrahymena pyriformis (a holotrichous ciliate). In S. mytilus, polytene chromosomes are formed in the young macronucleus (macronuclear Anlage). They are subsequently broken between the bands by ‘membranous’ partitions; the assembly of the membranes appears to be concomitant with the formation of the polytene chromosomes. The membranes in the Anlage appear to originate from fibrous material seen in the early Anlage. This fibrous material in the earlier stages is seen concentrated at several points along the border of the inner nuclear membrane. In the later stages it is seen in the interior of the Anlage, outlining the developing polytene chromosomes. As the chromosomes reach the maximum degree of polyteny, the fibrous material condenses to acquire a membranous appearance and extends into the interband regions. The Anlage throughout this period shows a progressive increase in size. Subsequently, the membranes enclose individually each band plus portions of the 2 adjacent interband regions of the polytene chromosomes to form a large number of vesicles. After vesicle formation the Anlage shrinks, and the chromatin inside the vesicles shows degradative changes. Finally, the vesicles disappear, the membrane degradation products appear at the nuclear membrane, and the Anlage now contains nucleoli. The Anlage increases its DNA content by multiple rounds of replication to become a mature macronucleus. The ultra-structural changes observed in the Anlage support the idea of genetic diminution (i.e. extensive DNA synthesis, elimination of many DNA nucleotide sequences, and amplification of the remaining DNA nucleotide sequences in a second period of DNA synthesis) proposed earlier on the basis of cytochemical, biochemical, and limited electron-microscope studies. In T. pyriformis, the macronuclear development differs substantially from that of Stylonychia. Features such as the formation and degradation of polytene chromosomes are absent in the macronuclear development of Tetrahymena; the young macronucleus in this cell becomes a mature macronucleus by progressive increment in size and chromatin content with no apparent genetic diminution. These observations agree with cytochemical studies on the macronuclear development of Tetrahymena.

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