Showing papers on "Heterochromatin published in 1975"
TL;DR: In situ hybridization with 3H 18S and 28S ribosomal RNA from Xenopus laevis has been used to study the distribution of DNA sequences coding for these RNAs (the nucleolus organizing regions) in the genomes of six mammals.
Abstract: In situ hybridization with 3H 18S and 28S ribosomal RNA from Xenopus laevis has been used to study the distribution of DNA sequences coding for these RNAs (the nucleolus organizing regions) in the genomes of six mammals. Several patterns of distribution have been found: 1) A single major site (rat kangaroo, Seba's fruit bat), 2) Two major sites (Indian muntjac), 3) Multiple sites in centromeric heterochromatin (field vole), 4) Multiple sites in heterochromatic short arms (Peromyscus eremicus), 5) Multiple sites in telomeric regions (Chinese hamster). — The chromosomal sites which bind 3H 18S and 28S ribosomal RNA correspond closely to the sites of secondary constrictions where these are known. However, the correlation is not absolute. Some secondary constrictions do not appear to bind 3H ribosomal RNA. Some regions which bind ribosomal RNA do not appear as secondary constrictions in metaphase chromosomes. — Although the nucleolus organizing regions of most mammalian karyotypes are found on the autosomes, the X chromosomes in Carollia perspicillata and C. castanea carry large clusters of sequences complementary to ribosomal RNA. In situ hybridization shows that the Y chromosome in C. castanea also has a large nucleolus organizing region.
229 citations
TL;DR: Knowing the base composition and base sequences of Drosophila satellites, it is concluded that AT richness may be a necessary but is certainly an insufficient requirement for quinacrine bright chromatin while GC richness may not be a sufficient requirement for the absence of qu inacrine or Hoechst brightness.
Abstract: Metaphase chromosomes of D. melanogaster, D. virilis and D. eohydei were sequentially stained with quinacrine, 33258 Hoechst and Giemsa and photographed after each step. Hoechst stained chromosomes fluoresced much brighter and with different banding patterns than quinacrine stained ones. In contrast to mammalian chromosomes, Drosophila's quinacrine and Hoechst bright bands are all in centric heterochromatin and the banding patterns seem more taxonomically divergent than external morphological characteristics. Hoechst stained D. melanogaster chromosomes show unprecedented longitudinal differentiation in the heterochromatic regions; each arm of each autosome can be unambiguously identified and the Y shows eleven bright bands. The Hoechst stained Y can also be identified in polytene chromocenters. Centric alpha heterochromatin of each D. virilis autosome is composed of two blocks which can be differentiated by a combination of quinacrine and Hoechst staining. The distal block is always Q−H− while the proximal block is, for the various autosomes, either Q−H−, Q+H− or Q+H+. With these permutations of Hoechst and quinacrine staining, D. virilis autosomes can be unambiguously distinguished. The X and two autosomes have H+ heterochromatin which can easily be seen in polytene and interphase nuclei where it seems to aggregate and exclude H− heterochromatin. This affinity of fluorochrome similar heterochromatin was best seen in colcemid induced multiple somatic non-disjunctions where H+ chromosomes were distributed to one rosette and H− chromosomes were distributed to another. Knowing the base composition and base sequences of Drosophila satellites, we conclude that AT richness may be a necessary but is certainly an insufficient requirement for quinacrine bright chromatin while GC richness may be a sufficient requirement for the absence of quinacrine or Hoechst brightness. Condensed euchromatin is almost as bright as Q+ heterochromatin. While chromatin condensation has little effect on Hoechst staining, it appears to be “the most important factor responsible for quinacrine brightness”. All existing data from D. virilis indicate that each fluorochrome distinct block of alpha heterochromatin may contain a single DNA molecule which is one heptanucleotide repeated two million times.
136 citations
Journal Article•
TL;DR: An analysis of the inherited pattern of C-band heterochromatin has been made in five pedigrees containing a total of 33 offspring, and the observed mosaic patterns provide suggestive evidence that such an event occurs in somatic cells as well as during meiosis.
Abstract: An analysis of the inherited pattern of C-band heterochromatin has been made in five pedigrees containing a total of 33 offspring that were available for analysis. The majority of variants were found to be inherited; however, at least seven of the 99 variants were not present in either parent, and an additional seven differed from the parental variant by either a morphological change or the appearance of mosaicism. It is believed that the polymorphism of human constitutive heterochromatin arises from a mismatching of the repetitive DNA sequences contained in these regions with subsequent unequal crossing over. Further, the observed mosaic patterns provide suggestive evidence that such an event occurs in somatic cells as well as during meiosis.
101 citations
96 citations
TL;DR: The frequency of sister chromatid exchanges (SCEs) was determined for the chromosomes of the Indian muntjac stained by the fluorescence plus Giemsa (FPG) or harlequin chromosome technique and the constitutive heterochromatin in the neck of this chromosome contained far fewer SCEs than expected on the basis of the amount of DNA.
Abstract: The frequency of sister chromatid exchanges (SCEs) was determined for the chromosomes (except Y2) of the Indian muntjac stained by the fluorescence plus Giemsa (FPG) or harlequin chromosome technique. The relative DNA content of each of the chromosomes was also measured by scanning cytophotometry. After growth in bromodeoxyuridine (BrdU) for two DNA replication cycles, SCEs were distributed according to the Poisson formula in each of the chromosomes. The frequency of SCE in each of the chromosomes was directly proportional to DNA content. A more detailed analysis of SCEs was performed for the three morphologically distinguishable regions of the X-autosome composite chromosome. The SCE frequency in the euchromatic long arm and short arm were proportional to the amount of DNA. In contrast, the constitutive heterochromatin in the neck of this chromosome contained far fewer SCEs than expected on the basis of the amount of DNA in this region. A high frequency of SCE, however, was observed at the point junctions between the euchromatin and heterochromatin.
94 citations
TL;DR: An analysis of the pattern of association of acrocentric chromosome with nonacrocentric chromosomes in human lymphocyte metaphases was performed, finding a general preference for the centric regions, most pronounced at the proximal segments of the long arms of chromosomes 1, 9, and 16, which is interpreted to reflect heterochromatin attraction during interphase.
Abstract: An analysis of the pattern of association of acrocentric chromosomes with nonacrocentric chromosomes in human lymphocyte metaphases was performed. This pattern in nonrandom with respect to chromosome length and intrachromosomal distribution. There is a general preference for the centric regions, most pronounced at the proximal segments of the long arms of chromosomes 1, 9, and 16, which is interpreted to reflect heterochromatin attraction during interphase. Comparison of the association patterns of homologous chromosome 1's differing with regard to the size of their heterochromatic regions corroborates this interpretation. The possible significance of heterochromatin attraction for the formation of spontaneous and induced chromosome anomalies is discused.
79 citations
TL;DR: The results are interpreted as indicating that this chromatin-associated RNA is more prevalently associated with the heterochromatic fraction of chromatin.
Abstract: Chromatin from TLT hepatoma cells, mouse liver cells, and mouse brain cells was fractionated by differential centrifugation into a pellet, enriched with heterochromatin, and a supernatant, enriched with euchromatin. The pellet was found to contain more than twice as much of a particular species of chromatin-associated RNA per milligram chromatin DNA as did the supernatant. This chromatin-associated RNA was also found to be associated with the transcriptionally inactive chromatin of mature avian erythrocytes. Bull sperm, whose genome is known to be completely inactive, was used as the source in the preparation of sperm heads. Bull sperm head RNA appeared to consist of a single, low molecular weight species which migrated on polyacrylamide gels at a rate just slightly slower than the aforementioned chromatin-associated RNA. The results are interpreted as indicating that this chromatin-associated RNA is more prevalently associated with the heterochromatic fraction of chromatin. It is postulated that this chromatin-associated RNA might constitute a structural component of heterochromatin.
70 citations
TL;DR: There is diversity among the human, gorilla and chimpanzee in both the size and location of concentrations of 5 MeC, supporting the idea that satellite DNA evolves more rapidly than DNA in the remainder of the chromosome.
Abstract: Fixed metaphase chromosomes of gorilla and chimpanzee were UV-irradiated to produce regions of single-stranded DNA and then treated with antibodies specific for the minor DNA base 5-methylcytosine (5 MeC). An indirect immunofluorescence technique was used to visualize sites of antibody binding. In the gorilla six pairs of autosomes contained major fluorescent regions, indicating localized regions of highly methylated DNA. These corresponded, with the exception of chromosome 19, to the major regions of constitutive heterochromatin as seen by C-banding. The Y chromosome also contained a highly fluorescent region which was located just proximal to the intense Q-band region. In the chimpanzee no comparable concentrations of highly methylated DNA were seen. Smaller regions of intense 5 MeC binding were present on perhaps six chimpanzee chromosomes, including the Y. Five of these corresponded to chromosomes which were highly methylated in the gorilla.--There is diversity among the human, gorilla and chimpanzee in both the size and location of concentrations of 5 MeC, supporting the idea that satellite DNA evolves more rapidly than DNA in the remainder of the chromosome.
65 citations
TL;DR: The G-banded karyotypes of 4 species of birds representing the orders Galliformes, Columbiformes and Musophagiformes were compared and the data obtained do not support reports of broad interordinal direct homology of the macrochromosomes of birds and refutes the idea of a primitive bird karyotype with 3 pairs of “A group” chromosomes.
Abstract: The G-banded karyotypes of 4 species of birds representing the orders Galliformes, Columbiformes and Musophagiformes were compared. Banding pattern homology between orders was limited to 5 major chromosome arms and the Z chromosome. Even in these major chromosome arms pericentric and paracentric inversions produced alteration of the banding pattern sequences. Addition of constitutive heterochromatin was responsible for changes in banding pattern in the Z chromosome. The chromosome banding patterns of an emydid turtle, Terrepene Carolina, 5 species of boid snakes of the genera Liasis, Acrantophis, and Sanzinia and the African clawed-frog, Xenopus muelleri, were also compared to the bird chromosome banding patterns. No homology was observed between any of these major groups: bird, snake, turtle, amphibian. However, intergrouphomology was apparent. — The data obtained do not support reports of broad interordinal direct homology of the macrochromosomes of birds and refutes the idea of a primitive bird karyotype with 3 pairs of “A group” chromosomes and 3 pairs of “B group” chromosomes. — The major mechanisms responsible for chromosome evolution in birds appear to be centric and tandem fusions, paracentric and pericentric inversions, and addition or deletion of heterochromatin.
65 citations
TL;DR: Human lymphocytes were grown for one replication cycle in BrdU, stained with 33258 Hoechst, exposed to UV light and subsequently treated with 2 x SSC and stained with Giemsa, revealing a previously unsuspected type of polymorphism within the constitutive heterochromatin of man.
Abstract: Human lymphocytes were grown for one replication cycle in BrdU, stained with 33258 Hoechst, exposed to UV light and subsequently treated with 2 x SSC and stained with Giemsa. This technique differentially stains the constitutive heterochromatin of chromosomes 1, 9, 15, 16, and the Y. In the heterochromatin of chromosome 9 both sister chromatids stained darkly and symmetrically but in the other four chromosomes the heterochromatin showed lateral asymmetry, one chromatid being darkly stained while its sister chromatid was as pale or paler than the rest of the chromosome. The lateral asymmetry is presumed to reflect an underlying asymmetry in distribution of thymine between the two strands of the DNA duplex in the satellite DNA component of the chromosomes. In some number 1 chromosomes compound lateral asymmetry was seen; darkly staining material was present on both sister chromatids although at any given point lateral asymmetry was maintained so that if one chromatid stained darkly the corresponding point on the sister chromatid was very pale. The pattern of compound lateral asymmetry varied among the number 1 chromosomes studied but was constant for any one homologue from one individual. This technique reveals a previously unsuspected type of polymorphism within the constitutive heterochromatin of man.
63 citations
TL;DR: In this paper, it was shown that for Drosophila virilis and Samoaia leonensis at least, each satellite DNA is condensed into a distinct heterochromatic mass during interphase.
Abstract: Cytological evidence is presented which shows that for Drosophila virilis and Samoaia leonensis at least, each satellite DNA is condensed into a distinct heterochromatic mass during interphase. This is seen as just one example of a general phenomenon in which chromatin containing a particular DNA sequence binds to other chromatin containing the same sequence. It is proposed that DNA sequence specific proteins can account for this phenomenon.
TL;DR: A comparison of C-bands and cold-sensitive segments clearly shows that negatively as well as positively reacting cold-induced segments are partly heterochromatic, partly euchromatic.
Abstract: The comparison of Hy- and C-bands reveals three types of heterochromatin (Hy+, Hy−, and Hy 0) inVicia faba. By C-banding, the total of constitutive heterochromatin is identified. The Hy-banded heterochromatin is restricted to the M-chromosome: The nucleolus-associated heterochromatin appears as two darkly stained (Hy+)-bands bordering the secondary constriction, while reduced staining (Hy−)-bands are located near the centromere. The heterochromatin of the S-chromosomes is of the (Hy 0)-type, i.e., it does not respond to the Hy-banding procedure. A complete karyogram of the C-banded chromosome complement is presented and discussed. A comparison of C-bands and cold-sensitive segments clearly shows that negatively as well as positively reacting cold-induced segments are partly heterochromatic, partly euchromatic.
TL;DR: Analysis by inter se complementation, pseudo-dominance tests with proximal mutations and allelism tests with known deficiencies provided evidence for at least two loci between the centromere and the light locu in 2L and one locus in 2R between the rolled locus and the Centromere, demonstrating functional genetic loci are found in heterochromatin, albeit at low density.
Abstract: To examine the genetic composition of proximal heterochromatin in chromosome 2, the detachment of compound second autosomes, for generating proximal deficiencies, appeared a promising method. Compound seconds were detached by gamma radiation. A fraction of the detachment products were recessive lethals owing to proximal deficiencies. Analysis by inter se complementation, pseudo-dominance tests with proximal mutations and allelism tests with known deficiencies provided evidence for at least two loci between the centromere and the light locus in 2L and one locus in 2R between the rolled locus and the centromere. The data further demonstrate that rolled, and probably light, are located within the proximal heterochromatin. Thus, functional genetic loci are found in heterochromatin, albeit at low density.
TL;DR: A number of observations suggest there are some non-histone protein unique to constitutive heterochromatin which are responsible for some of its properties such as interphase condensation, C-banding, frequent decreased quinacrine fluorescence, ectopic pairing, and ability to cause position effect.
TL;DR: Each block seems to contain only one DNA satellite and similar staining blocks, along with their respective satellite, appear or disappear as units during speciation; this was first suggested from a study of D. hydei sibling species and confirmed for the D. virilis group.
Abstract: CENTRIC heterochromatin in Drosophila metaphase chromosomes is organised into large blocks which show various degrees of condensation in prometaphase1 and various degrees of decondensation when living cells are Hoechst treated2. By sequential staining with the fluorescent dyes Hoechst and quinacrine, three different types of blocks are distinguishable in D. virilis. Each block seems to contain only one DNA satellite and similar staining blocks, along with their respective satellite, appear or disappear as units during speciation; this was first suggested from a study of D. hydei sibling species1 and here confirmed for the D. virilis group.
TL;DR: A further modification is described which allows one to follow the T-rich strand of the AT-rich satellite DNA of C-band heterochromatin of bromodeoxyuridine-Giemsa banding (BG-banding), which allows the formulation of several rules of chromosome organization.
Abstract: Hoechst 33258 fluorescent staining of bromodeoxyuridine substituted chromosomes provided a high resolution technique for following the segregation of replicated chromosomal DNA (Latt, 1973) Modifications have produced the same results after Giemsa staining (Wolff and Perry, 1975) Since this does not necessarily require Hoechst (Korenberg and Freedlander, 1975), we call this bromodeoxyuridine-Giemsa banding (BG-banding) We here describe a further modification which allows one to follow the T-rich strand of the AT-rich satellite DNA of C-band heterochromatin We call this TC-banding This technique was used to examine metacentric marker chromosomes found in mouse L-cells that contain many interstitial blocks of centromeric-type heterochromatin in each arm plus the usual two blocks of centromeric heterochromatin One of the advantages of this technique for such chromosomes is that it is possible to distinguish first from second cell cycle sister chromatid exchange and unambiguously detect centromeric sister chromatid exchange We found some chromosomes to have high rates of centromeric sister chromatid exchange After one cycle in bromodeoxyuridine we could examine the satellite polarity of the heterochromatic DNA Since there was no change in satellite polarity in any of the heterochromatic blocks, marker chromosomes could not have been formed by paracentric inversions, inverted insertions or inverted translocations These results allow the formulation of several rules of chromosome organization
TL;DR: Observations reveal that the human oocyte at the diplotene stage shows an amplification of the ribosomal cistrons, which is homologous to a more reduced scale, of this described from the inferior vertebrates.
Abstract: In the diplotene stage of the human oocyte, the processes of elaboration of the nucleolar material are amplified. The principal nucleoli are more voluminous but their relations with the secondary constrictions and the satellites of the D and G chromosomes are not modified. Numerous micronucleoli, frequently to the number of 15-20 this stage. The most remarkable point is their association to various segments of constitutive heterochromatin: centromeric regions, secondary constrictions of the C9 and probably of the A1 and E16. These observations reveal that the human oocyte at the diplotene stage shows an amplification of the ribosomal cistrons. This phenomenon is homologous, to a more reduced scale, of this described from the inferior vetebrates. Besides, the role of heterochromatin in the synthesis of nucleolar material without the intervention of the classic nucleolar organizers is suggested.
TL;DR: Experiments in which the heterochromatin of Drosophila was differentiated by means of treatment of the living gangliar cells with 33258 Hoechst, which is known to decondense the centric heterochrome of the mouse, are described.
Abstract: IN Drosophila melanogaster the heterochromatin comprises the whole of the Y chromosome, about the proximal third of the X chromosome and the centromeric areas of chromosomes 2 and 31–4. It appears throughout the cell cycle as darkly staining and highly condensed chromatin2,3 and replicates later than euchromatin during the synthetic period5. The heterochromatin of Drosophila is considered genetically inert because it contains very few mappable genes, although it has marked genetic effects in determining the well known position effect1. It has recently been found that the heterochromatin of Drosophila corresponds to the C bands6 and contains highly repetitive DNA7–12. None of these characteristics has, however, so far been of any use in solving the problem of the functional role of the heterochromatin. On the other hand, Drosophila offers unique possibilities for solving this problem, since in this organism it is possible to construct chromosomes containing different quantities of centromeric heterochromatin4,13 and thus study the functions of this material. Obviously this type of approach requires a preliminary study on the possible heterogeneity of the heterochromatin. An initial result in this type of study has been obtained by showing that the heterochromatin regions of D. melanogaster fluoresce differently after staining both with quinacrine14–16 and with the compound 33258 Hoechst17. Here we describe experiments in which the heterochromatin of Drosophila was differentiated by means of treatment of the living gangliar cells with 33258 Hoechst, which is known to decondense the centric heterochromatin of the mouse18.
TL;DR: In situ hybridization to salivary gland polytene chromosomes and to metaphase chromosomes from neural ganglia indicated that polypyrimidines complementary to polypurine RNA are located in heterochromatin, and this location is verified by using a cytological marker of chromosomes 2.
TL;DR: The differences which were found between the distribution of the cRNAs from the two chromatin fractions may be associated with differences in genetic activity.
TL;DR: Observations are consistent with an earlier report of heterochromatic connections between telomeres of Allium cepa chromosomes and support the hypothesis that constitutiveheterochromatin and repetitive DNA may be involved in chromosome associations.
Abstract: A Giemsa staining technique that is thought to indicate the site of constitutive heterochromatin and repetitive DNA was used to stain the telomeres of Secale cereale (rye) chromosomes. Heterochroma...
TL;DR: The DNA replication patterns of the terminal S phase of three species of Mus were analyzed by tritiated thymidine autoradiography and indicated that in M. dunni there are at least two types of heterochromatin.
Abstract: The DNA replication patterns of the terminal S phase of three species of Mus were analyzed by tritiated thymidine autoradiography. The centromeric heterochromatin of M. fulvidiventris is the latest component to finish DNA synthesis. The Y chromosome finishes replication earlier than the centromeric heterochromatin. The centromeric heterochromatin of M. musculus, on the other hand, is not the latest component to finish DNA synthesis. At the very late S phase, grains are found in the euchromatic arms instead of the heterochromatic areas. The “hot X” and the “hot Y” can be identified in the majority of, but not all, cases. The heterochromatic short arms of the autosomes in M. dunni finish DNA replication earlier than many areas in the euchromatic long arms and the heterochromatin of the sex chromosomes. This indicates that in M. dunni there are at least two types of heterochromatin. The late-replicating zones in the euchromatic long arms are distinctly banded. This banded grain pattern can be seen in all Mus species observed, but in M. dunni it is most exaggerated. Late-replicating chromosome segments can be demonstrated also by 2+ cycles of BUdR incorporation and Giemsa staining.
TL;DR: The addition of a heterochromatic chromosome segment to either one or both homologues is described in autosomes B5 and B12 of the squirrel monkey, Saimiri sciureus.
Abstract: Variant structural homozygosity, observed previously only in plants and insects, is reported herein for the first time in mammalian chromosomes. The addition of a heterochromatic chromosome segment to either one or both homologues is described in autosomes B5 and B12 of the squirrel monkey, Saimiri sciureus.
TL;DR: Analysis of total liver, liver nuclei, and nuclear fractions obtained from mice given either deionized water (control) or deionization water containing cupric chloride (experimental) revealed the presence of copper in all samples tested, suggested by the majority of metal binding to this fraction; there was no significant metal accumulation in euchromatin.
TL;DR: In situ hybridization studies indicate that these interstitial bands contain typical mouse satellite DNA, suggesting that specific chromosomes in several mouse lines have interstitial C-bands.
Abstract: Specific chromosomes in several mouse lines have interstitial C-bands. In situ hybridization studies indicate that these interstitial bands contain typical mouse satellite DNA.
TL;DR: In this article, a modified Giemsa staining technique was used to identify regions of centromeric (C-) heterochromatin in mitotic and meiotic chromosomes.
Abstract: Additional samples from a discrete population of the pygmy grasshopper Tettigidea lateralis, at the periphery of the species range, have shown that the frequency of the B-chromosomes has remained stable over a two year period (30–35%), and that there is no significant difference for this metric in the two sexes. The intensity of the preferential movement of the B with the X at male first meiotic division has also remained constant in time and homogenous in different individuals. Hence it is possible that this distortional effect plays a role in the equilibrium frequency of the B in the population. The B's may possess special adaptive properties under ecologically marginal conditions, since in a number of more ‘central’ demes they occur at much lower frequencies (7–9%). — Unique morphological and/or behavioural variants of the standard B were encountered in addition to distinct cases of spontaneous fragmentation of A elements. The meiotic behaviour and chromatic expression of these centric fragments provide evidence on the possible origin and evolution of supernumeraries. A modified Giemsa staining technique has been used to identify regions of centromeric (C-) heterochromatin in mitotic and meiotic chromosomes. The C-banding pattern of the X and the allocyclically similar B is compared. It suggested that the B may have originated from the X by deletion of centromeric heterochromatin. This may have affected the centromere “strength” of the nascent B leading to its preferential movement with the X at anaphase I.
TL;DR: The sites of unscheduled DNA synthesis (UDS) induced by ultraviolet or ionizing radiations in human lymphocytes are not randomly distributed in the nuclear DNA.
Abstract: The sites of unscheduled DNA synthesis (UDS) induced by ultraviolet or ionizing radiations in human lymphocytes are not randomly distributed in the nuclear DNA. Examinations of radioautographs of 1.0-μm nuclear sections show that about 70% of the grains are over the 33% of the nuclear area adjacent to the nuclear membrane. This is found whether the bulk of the DNA, which is in heterochromatin masses, is peripherally distributed, is dispersed throughout the nucleus, or is homogeneously distributed. This peripheral distribution of UDS is maintained when incubation time is increased from 0.5 to 4 hr, and when cells are stimulated for 18 hr by phytohemagglutinin prior to irradiation. The distribution of UDS sites is not simply related to the distribution of euchromatin (active) or heterochromatin (repressed) within the nucleus.
TL;DR: In this article, a chromosomal polymorphism was described from a Maui (Hawaii) population of D. disjuncta, which is specifically associated with the acquisition of an extra heterochromatic segment in a mitotic chromosome.
Abstract: A chromosomal polymorphism is described from a Maui (Hawaii) population of D. disjuncta. The acquisition of an extra heterochromatic segment in a mitotic chromosome is specifically associated with ...
Journal Article•
01 Mar 1975-Canadian journal of genetics and cytology. Journal canadien de génétique et de cytologie
TL;DR: A chromosomal polymorphism is described from a Maui (Hawaii) population of D. disjuncta that suggests the possible effect of a chromosomal break-point within the area of centromeric heterochromatin in causing an increase in the amount of repetitive DNA.
TL;DR: The positions of chromosomes 1 and Y inside human spermatozoa were determined by differential staining techniques and in 85/100 cells the two chromosomes were in close contact and in association with a vacuole.
Abstract: 1 and Y inside human spermatozoa were determined by differential staining techniques In 85/100 cells the two chromosomes were in close contact and in association with a vacuole This observation is in contrast to previous findings for chromosome No 9 and the Y-chromosome whose positions do not appear to be correlated Soon after the introduction of the fluorescence staining technique for the detec¬ tion of the Y heterochromatin in interphase nuclei (Pearson et al, 1970), it was shown that the Y-chromosome could also be demonstrated in human spermato¬ zoa (Barlow & Vosa, 1970; Pearson & Bobrow, 1970) and was associated with vacuoles (Pawlowitzki & Bosse, 1971) Alternative techniques have now been developed for chromosomes No 9 (Bobrow et al, 1972) and No 1 (Geraedts & Pearson, 1973) which can also be used for demonstrating the heterochromatin of these chromosomes in ejaculated spermatozoa The staining procedures involved are of the C-banding type, and reveal a darkly stained chromosome body against a less pronouncedly stained nuclear background In one study (Geraedts & Pearson, 1975), it was demonstrated that there appeared to be no correlation between the position of the Y-chromosome and chromosome No 9 The purpose of the present study was to investigate the spatial relationship between the Y-chromosome and chromosome No 1 within the human sperm nucleus