Association of RB97D, an RRM protein required for male fertility, with a Y chromosome lampbrush loop in Drosophila spermatocytes

The Y chromosome of Drosophila melanogaster, which is required only for male fertility, contains six loci that are essential for spermatogenesis. In primary spermatocytes, three of these loci form large lampbrush loops containing RNA transcripts and associated proteins. The identities and functions of these Y chromosome loop-binding proteins are largely unknown. This report demonstrates that the RB97D protein, which is essential for spermatogenesis, bound to a specific lampbrush loop. RB97D contains two copies of a well-characterized RNA binding domain, the RNA recognition motif, followed by a proline-glutamine rich domain. Immunohistochemical and immunofluorescence experiments showed that in the testis, RB97D was found only in primary spermatocyte nuclei and associated with the C loop from the ks-1 fertility locus in an RNAse-sensitive manner. The anti-RB97D antibodies also bound a single Y chromosome loop in D. hydei, suggesting that the protein and its loop-binding function have been evolutionarily conserved. These results demonstrate that the proteins that bind lampbrush loops can be essential for fertility. Since RB97D was present only premeiotically, its function is likely to be directly related to the metabolism of the C loop transcripts.

Alpha and beta heterochromatin in polytene chromosome 2 of Drosophila melanogaster

The formation of alpha and beta heterochromatin in chromosomes of Drosophila melanogaster was studied in salivary glands (SGs) and pseudonurse cells (PNCs). In SGs of X0, XY, XYY, XX and XXY individuals the amounts of alpha heterochromatin were similar, suggesting that the Y chromosome does not substantially contribute to alpha heterochromatin formation. Pericentric heterochromatin developed a linear sequence of blocks in PNCs, showing morphology of both alpha and beta heterochromatin. In situ hybridization with Rsp sequences (Ho clone) revealed that the most proximal heterochromatic segment of the mitotic map (region h39) formed a polytenized block in PNCs. Dot analysis showed that the clone had a hybridization rate with PNC-DNA very close to that with DNA from mainly diploid head cells, whereas the homologous SG-DNA was dramatically underrepresented. A similar increase of DNA representation in PNC was found for AAGAC satellite DNA. The mitotic region h44 was found not to polytenize in the SG chromosome, whereas in PNC chromosome 2 this region was partly polytenized and presented as an array of several blocks of alpha and beta heterochromatin. The mapping of deficiencies with proximal breakpoints in the most distal heterochromatin segments h35 in arm 2L and h46 in 2R showed that the mitotic eu-heterochromatin transitions were located in SG chromosomes distally to the polytene 40E and 41C regions, respectively. Thus, the transition zones between mitotic hetero- and euchromatin are located in banded polytene euchromatin. A scheme for dynamic organization of pericentric heterochromatin in nuclei with polytene chromosomes is proposed.

Gender identification of human hair using fluorescence in situ hybridization

Identification of the gender of hair represents relevant medicolegal evidence in criminal cases. The efficacy of Fluorescence In Situ Hybridization (FISH) using chromosome X and Y centromeric probes was tested to determine its ability to identify correctly the gender of hair. In this preliminary study, FISH correctly identified the gender of cells from hair as old as 26 days. The technique is accurate, rapid, sensitive, easily performed, and readily available. As a forensic laboratory technique, FISH shows great promise.

In situ detection of individual transplanted bone marrow cells using FISH on sections of paraffin-embedded whole murine femurs

Studies of transplantation biology rely on the detection of donor hemopoietic cells in transplant recipients. Traditionally this has been achieved through ex vivo techniques, including flow cytometric analysis of cell surface markers to detect cells expressing specific epitopes, histochemical detection of cytoplasmic proteins, and the detection of Y chromosome-specific sequences by DNA hybridization. Studies using congenic models, such as the Ly5.1/5.2 mouse, or the utilization of fluorescent dyes, such as PKH-26, have allowed more in-depth analysis of transplantation, beginning to address key issues such as cell homing through cell tracking and elucidation of the "stem cell niche." However, these methods are limited by labeling sensitivity, specificity, crossreactivity and, in the case of PKH-26 labeling, the number of cell divisions the transplanted cells can make before the signal disappears. We have developed a fluorescent in situ hybridization (FISH) technique that utilizes a murine Y chromosome-specific "painting" probe to identify in situ individual transplanted male cells in paraffin-embedded sections of female whole bone marrow while maintaining good morphological integrity. This method is highly sensitive and specific, labeling more than 99% of male cells and no female cells, allowing each transplant to be assessed at the individual cell level. The technique provides unique opportunities to follow the path taken by transplanted cells, both during homing into the marrow and through their maturation and differentiation into mature, functional hemopoietic cells.

Gender preselection in mammals: an overview

Recent advances in the separation of X and Y chromosome bearing spermatozoa have led to the availability of a method (Beltsville Sperm Sexing Technology) to preselect the sex in several mammals. Progeny using this procedure have been produced in cattle, sheep, swine and laboratory animals. Mammalian sperm are inherently different in that the X sperm carries from 2.8 to 7.5% more DNA than the Y sperm. Individual sperm DNA can be determined and used as the differentiating characteristic with flow cytometry and cell sorting instrumentation especially modified to measure small amounts of DNA in sperm. The process utilizes the fluorochrome Hoechst 33342 to bind to the DNA. The relative DNA is measured by passing the living sperm through a laser beam and collecting the light energy from the individual sperm. Data is acquired and used to select the particular sperm for deflection into collection tubes. The proportions of sorted X and Y sperm in each tube can be validated by reanalyzing an aliquot for DNA content. This value is then used to predict the outcome of fertilization and subsequent gestation. The sorted sperm are used to inseminate eggs via in vitro fertilization (IVF) or by surgical insemination into the oviduct or the uterus of appropriate females. Sperm are sorted at the rate of 0.5 million per hour for most species with the expectation of 90% or greater of one sex or the other being born. Progeny in cattle using IVF have been produced at greater than 90% accuracy. Rabbits have produced greater than 90% females using this process. Progeny produced from pigs average 85% for one sex or the other. All progeny produced (N = or > 300) have exhibited completely normal morphological appearance and normal reproductive function. Because of the inability to obtain large numbers of sorted sperm in a short amount of time, the technologies use for regular artificial insemination would not be practical in most domestic species. This sexing technology however is very applicable where IVF, intrauterine or intratubal insemination are convenient means for producing offspring. In addition, the recent advent of ultrasound guided insemination in cattle may provide and opportunity to use this technology for much lower numbers of sperm per insemination than previously thought possible. Using less than 2 x 10 sorted X or Y sperm would move the technology one step closer to practicality.

Sex determination of ancient human skeletons using DNA

A method for determining the sex of human skeletons was developed using molecular genetic techniques. The amelogenin gene, found on the X and Y chromosomes, was examined using the polymerase chain reaction (PCR) and a nonradioactive dot blot procedure. DNA was analyzed from 20 modern individuals of known sex and 20 skeletons from an archaeological site in central Illinois dating to A.D. 1300. An independent assessment of the sex of each skeleton was made according to standard osteological methods. The sex of 19 ancient and 20 modern individuals was accurately determined using this molecular genetic technique. Molecular sex determination will be especially useful for juvenile and fragmentary remains when it is difficult, or impossible, to establish an individual's sex from morphological features.

Detection of Y-chromosome sequences in patients with X-chromosome abnormalities

The polymerase chain reaction was used to test 18 adults and eight fetuses with numerical or structural X-chromosome abnormalities for the presence of nine Y-specific loci. Y-chromosomal DNA was detectable in one adult patient with X-chromosome mosaicism. This study and previous reports provide evidence to support further screening of patients with X-chromosome abnormalities for the presence of Y-chromosomal DNA sequences. Long-term follow-up of patients with Y-chromosomal sequences is required to determine the risk of gonadal neoplasms and other abnormal phenotypes.

Dysgerminoma and gonadal dysgenesis in a 46,XX female with no evidence of Y chromosomal DNA

The occurrence of dysgerminoma in dysgenetic gonads without Y chromosomal influence is exceptionally rare. We used Southern blot hybridization of Y-DNA probes to genomic DNA to search for any Y-related influence in a patient with a dysgerminoma, dysgenetic gonads, and a 46,XX karyotype. No Y-specific DNA was found at 11 loci representing the short arm, centromere, and long arm. This absence of any Y-DNA leaves open to question the absolute requirement of Y-related influence in the development of dysgerminoma in dysgenetic gonads.

Detection of Y-bearing porcine spermatozoa by in situ hybridization using digoxigenin-labeled, porcine male-specific DNA probe produced by polymerase chain reaction

This study was carried out to determine whether Y-bearing porcine spermatozoa could be detected by in situ hybridization using a digoxigenin (Dig)-labelled DNA probe specific to the Y chromosome produced by polymerase chain reaction (PCR). A conventional PCR (with Dig-dUTP) was performed using a set of oligonucleotide primers (5'-AAGTGGTCAGCGTGTCCATA-3' and 5'-TTTCTCCTGTATCCTCCTGC-3') for 236 bp fragment of porcine male-specific DNA sequence and 1.25 x 10(4) template white blood cells obtained from a boar. When fluorescence in situ hybridization with the Dig-labelled DNA probe was applied to the metaphase chromosome spreads prepared from both boar and gilts, the fluorescein signal was only detected on the long arm of the Y chromosome. In addition, immunocytochemical detection with the Dig-labelled DNA probe and alkaline phosphatase-labeled anti-Dig was applied to both sperm nuclei pretreated with dithiothreitol and white blood cells; 51% of sperm nuclei and 96% of white blood cells obtained from boar were labelled, whereas none of white blood cells obtained from gilts were labelled with the Dig-labelled DNA probe. The results indicated that in situ hybridization with porcine male-specific DNA probe produced by PCR made possible the direct visualization of Y-bearing porcine spermatozoa by in situ hybridization.

Bovine SRY gene locus: cloning and testicular expression

The bovine SRY gene was cloned by a combination of anchored polymerase chain reaction (PCR) amplification of genomic restriction fragments and reverse transcription-PCR (RT-PCR) of testicular RNA. We report 1800 bp of combined genomic and cDNA sequences including 911 bp of 5' upstream sequences, an open reading frame of 687 bp, and 202 bp of sequences corresponding to the 3' end of the mRNA. The bovine SRY gene encodes a deduced (predicted on the basis of a cDNA sequence) protein product of 229 amino acids, with sequence conservation between species, notably in the region of the high-mobility group (HMG) domain or HMG box. Outside of the HMG box, the bovine SRY structure shows greater resemblance to the human SRY than to the mouse Sry. As with human SRY promoter sequences, putative binding sites for Sp1 and for SRY itself are seen in the bovine SRY promoter region. Unlike the human SRY promoter, CAAT and TATA box motifs are present in the bovine sequences. Southern analysis and PCR amplification of male and female bovine genomic DNA show that the described sequences are specific to the Y chromosome. Northern analysis of bull testicular RNA demonstrated low levels of expression of the bovine SRY gene in adult testes with a major poly(A) species at 1.9 kb. RT-PCR amplification of bull testicular RNA revealed multiple sites of polyadenylation, but sequencing showed no consensus polyadenylation signal.

Osteoclast development in the coculture system of periostless metatarsal bones and hemopoietic cells studied by in situ hybridization with a probe for Y chromosomes

In the coculture system of periostless metatarsal bones of 17-day-old fetal mice and osteoclast progenitors, osteoclasts will develop. Our goal in the present report was to provide further evidence that in the coculture system of fetal metatarsal bone rudiments with hemopoietic cells, the osteoclasts developing inside the bone rudiments are exclusively derived from the cells suspended in the plasma clot and not from endogenous precursor cells of the bone explants themselves, by using the technique of in situ hybridization with a probe for the mouse Y chromosome. Osteoclast formation in unstripped male metatarsal rudiments, occurring after 3-4 days of culture, was compared with osteoclast formation in cocultures of female metatarsal rudiments and male bone marrow cells, occurring after 5-6 days of culture. Osteoclasts were recognized by their tartrate-resistant acid phosphatase activity. In paraffin sections of cultured male metatarsals, the mean percentage of microscopically identifiable osteoclast nuclei, in which the Y chromosome could be detected, was 43.1 +/- 4.2% (n = 12). For cocultures of female metatarsal bones and male bone marrow cells this mean percentage was 40.9 +/- 5.7% (n = 17). Statistical comparison by means of the two sample t-test indicated no significant difference in the percentages of osteoclast nuclei containing the Y chromosome for both groups. We concluded that the osteoclasts do derive from cocultured cells and not from precursor cells in the bone explant itself.(ABSTRACT TRUNCATED AT 250 WORDS)

Application of polymorphic DNA sequences to differentiate the origin of decomposed bovine meat

Two bovine meat samples were analysed although the samples were already in a state of advanced decomposition. The isolated DNA was extremely degraded and not suitable for conventional DNA fingerprinting (profiling), thus the polymerase chain reaction (PCR) was applied to screen for a Y-chromosome specific fragment and the loci of the two milk proteins kappa-casein and beta-lactoglobulin. Both samples contained Y-chromosome specific DNA and the kappa-casein genotype AA but they differed at the beta-lactoglobulin locus (BB versus AB). Thus a different origin (carcass) could be verified for the two samples and a subject was exonerated from a case of meat larceny.

Familial true hermaphroditism: paternal and maternal transmission of true hermaphroditism (46,XX) and XX maleness in the absence of Y-chromosomal sequences

We report on 46,XX true hermaphroditism and 46,XX maleness coexisting in the same pedigree, with maternal as well as paternal transmission of the disorder. Molecular genetic analysis showed that both hermaphrodites as well as the 46,XX male were negative for Y-chromosomal sequences. Thus, this pedigree is highly informative and allows the following conclusions: first, the maternal as well as paternal transmission of the disorder allows the possibility of an autosomal dominant as well as an X-chromosomal dominant mode of inheritance; second, testicular determination in the absence of Y-specific sequences in familial 46,XX true hermaphrodites as well as in 46,XX males seems to be due to the varying expression of the same genetic defect; and third, there is incomplete penetrance of the defect.

Partial reconstruction of the lampbrush loop pair Nooses on the Y chromosome of Drosophila hydei

We present the analysis of genomic DNA fragments that were isolated as potential segments of the lampbrush loop pair Nooses on the short arm of the Y chromosome of Drosophila hydei. More than 300 kb of DNA were recovered in BamHI lambda and cosmid clone groups. This DNA is composed of the Y-specific ay1 family of repetitive DNA sequences, and of other repetitive DNA sequences, which at least in part are also located elsewhere in the genome (Y-associated sequences). Two additional classes of DNA fragments were obtained from an EcoRI library. One of them consists of ay1 repeats without apparent interspersion, including a total of more than 300 kb of DNA. The other is composed of tandemly repeated YsI sequences, a Y-specific sequence derived from ay1. This class includes more than 400 kb of DNA, which is also not interspersed by other sequences. Our results show that only the ay1 repeats interspersed by Y-associated DNA sequences can represent parts of the 260 kb transcription unit forming the lampbrush loop, whereas the ay1 and YsI repeats without interspersion form separate and nontranscribed clusters of repetitive DNA.

Localization of the lampbrush loop pair Nooses on the Y chromosome of Drosophila hydei by fluorescence in situ hybridization

We have used fluorescence in situ hybridization to map the positions of the different repetitive DNA sequences from the region forming the lampbrush loop pair Nooses on the Y chromosome of Drosophila hydei. This region harbours a megabase cluster of tandemly organized repeats of the Y-specific ay1 family and a megabase cluster of tandem repeats of the related Y-specific YsI family. In addition, ay1 repeats also occur in short blocks that are interspersed by other repetitive DNA sequences that we call Y-associated, since they have additional copies on other chromosomes. Using specific probes for ay1, YsI and Y-associated DNA sequences, we show that there is one large proximal cluster of YsI repeats and one, more distally located, large cluster of ay1 repeats. The Y-chromosomal copies of the Y-associated sequences are located in the most distal part of the ay1 cluster. This is consistent with the juxtaposition of ay1 and Y-associated sequences in more than 300 kb of cloned genomic DNA. Since both ay1 and Y-associated sequences have been shown to be transcribed in the Nooses, the lampbrush loop is formed in a distal region of the short arm of the Y chromosome, adjacent to the terminally located nucleolus organizer region. The clusters of homogeneous ay1 and YsI repeats are of no functional significance for the formation of the lampbrush loop.

Metaphase karyotypes of Anopheles of Thailand and Southeast Asia: I. The Hyrcanus Group

Metaphase karyotypes of 6 species of the Hyrcanus Species Group of the subgenus Anopheles show constitutive heterochromatin variation in X and Y chromosomes. Anopheles peditaeniatus exhibits the most extensive variation in the size and shape of heterochromatic sex chromosomes, with 3 types of X and 5 types of Y chromosomes. Anopheles nitidus shows the least variation, with only 2 types of X chromosomes. Anopheles sinensis and An. crawfordi each have 2 forms of metaphase karyotype in the heterochromatin of the Y chromosome. It is not known whether the 2 forms of metaphase karyotype in these 2 species represent inter- or intraspecific differences. The 2 forms of heterochromatic sex chromosomes observed in An. argyropus and An. nigerrimus may suggest the existence of sibling species complexes within each of these species.

Sex chromosomes, recombination, and chromatin conformation

We review what is known about the transcriptional inactivation and condensation of heteromorphic sex chromosomes in contrast to the activation of homomorphic sex chromosomes during meiotic prephase in animals. We relate these cytological and transcriptional features to the recombination status of the sex chromosomes. We propose that sex chromosome condensation is a meiotic adaptation to prevent the initiation of potentially damaging recombination events in nonhomologous regions of the X and Y chromosome.

Detection of male cells in mixtures containing varying proportions of male and female cells by fluorescence in situ hybridization and G-banding

The efficiency and sensitivity of fluorescence in situ hybridization (FISH) and G-banding for the detection of male cells in mixtures of male and female cells derived from peripheral blood (PB) and bone marrow (BM) are compared. Zero false positive and negative rates were obtained with G-banding in all studies. False positive rates obtained with FISH were low (0-2.5%) in both PB and BM. False negative rates varied from 0-13.3%. Variations due to differences in fluorescent counterstain or scorers were not significant and in some cases the percentage of Y-positive cells as determined by FISH agreed more closely with the estimated frequency of male cells than that obtained by G-banding. The minimum limits of detection for FISH were 5% male cells on counting 500 PB or BM interphases; 10% male cells on counting 100 PB metaphases; and 20% male cells on counting 50 BM metaphases. This is in agreement with the theoretical limits of detection [95% confidence limit (CL)]. However, minimum levels of detection for female cells were below the 95% CL. It was not possible to reliably distinguish 95% female cells from 100% on counting 500 PB or BM interphases; 90% from 100% on counting 100 PB metaphases; or 80% from 100% on counting 50 BM metaphases.

Prenatal sex determination from maternal peripheral blood using the polymerase chain reaction

We have investigated the use of a nested polymerase chain reaction assay for the detection of a fetal-specific Y-chromosomal sequence (DYS14) from DNA extracted from unsorted maternal peripheral blood. Serial dilutions of male DNA into female cord blood DNA indicated that the assay could detect an equivalent of a single male cell in 300,000 female cells. The assay exhibited absolute specificity for male DNA with no amplification from a DNA panel obtained from 10 female cord blood samples. When used on DNA extracted from unsorted peripheral blood from a series of pregnant women, the predictive values of a positive test for a male fetus were 86%, 67% and 87% in the first, second and third trimesters, respectively. We have also demonstrated that retesting the samples allows the detection of a proportion of male-bearing pregnancies with a high degree of accuracy, in that all 15 women who gave positive signals in two consecutive amplifications had male fetuses. We have also applied the test at 8 weeks postpartum to eight women who had previously delivered male babies; no Y-specific signal could be detected in any of them, suggesting that most women have cleared their circulation of fetal cells by 8 weeks after parturition.

Sexing of mouse preimplantation embryos by detection of Y chromosome-specific sequences using polymerase chain reaction

Detection of genes known to be present on the mammalian Y chromosome was adapted for sexing mouse early embryos using the polymerase chain reaction (PCR) method. Sry and Zfy genes located in the sex-determining region of the Y chromosome were chosen for Y-specific target sequences, and DXNds3 sequence on the X chromosome was chosen for control. The two-step PCR method using two pairs of primers for each of the target sequences was employed for detecting the sequences. When DNAs of male and female mice were amplified with these primers, male-specific fragments were detected even in DNAs that were equivalent in amount to two cells. Mouse embryos at the two-cell stage were separated into two individual blastomeres, and one blastomere was karyotyped at the second cleavage. The remaining blastomere was subjected to PCR amplification immediately or after having been cultured for 48 h up to the morula stage. The Sry and Zfy sequences were detected in about half the embryos; detection of the Sry and Zfy sequences corresponded exactly to the presence of the Y chromosome, except in one sample of male morula in which embryos may have been lost before the PCR amplification. It is concluded that the sex of mouse preimplantation embryos can be accurately determined through detection of the Y-specific sequences using the two-step PCR method, even with the single blastomeres separated at the two-cell stage.

Molecular analysis of the sex-determining region from the Y chromosome in two patients with Frasier syndrome

In the Frasier syndrome there is an association between XY gonadal dysgenesis and chronic renal failure. Owing to an observed sex reversal, the Y chromosomes of two girls with this syndrome have been analyzed. Using molecular-biology techniques, no major alterations of the known sex-determining area of the Y chromosome were found. Furthermore, the sequence did not reveal impairment of the recently described testis-determining factor SRY. These data suggest that in the Frasier syndrome, XY sex reversal and renal failure could be the result of either faulty gene(s) located downstream in the sex differentiation pathway during embryogenesis, or impaired SRY regulation. Preliminary results on the Wilms' tumor suppressor gene WT1, a candidate for acting downstream to SRY, are also provided.

Sex determination of forensic samples by dual PCR amplification of an X-Y homologous gene

Sex determination by polymerase chain reaction (PCR) analysis of the X-Y homologous amelogenin gene is highly reliable since the detection of an X-specific amplified fragment validates the procedure. Previously, we reported that 250 ng of template DNA are required for sex determination by this method. We report here a refinement of the technique to include dual PCR. Dual PCR using two sets of primers results in the detection of X- and Y-specific amplified fragments from as little as 0.005 ng of template DNA. This is a powerful technique for the analysis of trace forensic samples and its application is discussed.

A polymerase chain reaction (PCR) method for sex and species determination with novel controls for deoxyribonucleic acid (DNA) template length

Human X and Y chromosome alpha-satellite sequences lying within higher order repeats were amplified by the polymerase chain reaction (PCR) in genomic deoxyribonucleic acid (DNA) isolated from blood, bone, and several other tissues and specimens of potential forensic science interest. X and Y sequences could be coamplified under some of the PCR conditions employed. Monomorphic sequences in the 3'-apolipoprotein B gene (designated "H") and in an alpha-satellite higher order repeat on Chromosome 17 (p17H8, D17Z1) were likewise amplified in the specimens. X and Y sequence amplification can provide information about the sex of origin. Amplification of the X, H, and D17Z1 sequences was found to be primate-specific among the common animals tested and can thus provide species of origin information about a specimen. The authors suggest that amplification of X and D17Z1 or H sequences might provide "relaxed" and "stringent" controls for appropriate PCR amplification tests on forensic science specimens. Testing was carried out using PCR protocols that employed Thermophilus aquaticus (Taq) and Thermus flavis (Replinase) thermostable DNA polymerases.

Heterochromatin characterization of sex chromosomes in Triturus marmoratus (Urodela, Salamandridae)

The sex chromosomes of the Iberian marbled newt, Triturus marmoratus, were studied using various banding techniques, including restriction enzyme/nick translation (RE/NT) procedures. Four types of heterochromatin on the sex chromosomes could be distinguished: (1) distamycin A/DAPI and chromomycin A3/distamycin A positive, EcoRI/NT negative, and HaeIII/NT and HinfI/NT positive; (2) distamycin A/DAPI and chromomycin A3/distamycin A positive, but RE/NT negative; (3) AT rich, but RE/NT negative; and (4) distamycin A/DAPI and chromomycin A3/distamycin A positive, EcoRI/NT and HinfI/NT negative, but HaeIII/NT positive. These data suggest a common origin for the terminal heterochromatic domains of both the X and Y chromosomes in this species.

Deoxyribonucleic acid and cytological detection of Y-containing cells in an XX hypospadiac boy with polyorchidism

A hypospadiac boy with a hypoplastic penis and an apparent 46,XX karyotype in blood and testis cultures is described. Exploratory laparotomy and bilateral gonadal biopsy revealed the presence of 2 testes in the right and 1 in the left hemiscrotum, each of which only showed hypoplastic testicular tissues histologically. Uncultured testis smears showed Y chromatin in approximately 20% of the cells. Also, the Southern blot and polymerase chain reaction analyses detected a weak but distinct signal of Y chromosome-derived deoxyribonucleic acid sequences in the perineal skin but not in the blood lymphocytes. The results indicated that the boy had a small proportion of Y chromosome-containing cells in the form of mosaicism in limited tissues, such as the testes and perineal skin. This finding may have implications in the genesis of testes in some cases of XX patients, and true hermaphrodites or male pseudohermaphrodites with an apparent 46,XX karyotype. To our knowledge, this appears to be the first case of polyorchidism with an identified chromosome abnormality.

Nucleotide sequence of p49a, a genomic Y-specific probe with potential utilization in sex determination

The nucleotide sequence of probe 49a, a genomic polymorphic probe located on the long arm of the Y chromosome, is described. It is an untranslated sequence of about 750 bp with a high A + T content. This sort of selectively neutral sequence can be used with the polymerase chain reaction in sex determination.

Detection of Y chromosome by in situ hybridization in combination with membrane antigens by two-color immunofluorescence

Discrimination between donor and recipient peripheral blood cells through detection of the Y chromosome can be useful to document chimerism and engraftment after sex-mismatched bone marrow transplantation. Currently applied methods are hampered by the selection of cells (e.g., karyotyping of cells in metaphase) or by the fact that the detection of Y chromosome by in situ hybridization with specific probes does not allow further characterization of the cells. Although quinacrine staining of Y chromosomes can be performed on cells previously marked for membrane antigens, this staining is not fully discriminative between male and female cells. To circumvent this, a technique has been developed, in which mononuclear cells in suspension were stained for membrane antigens by the consecutive use of monoclonal antibodies and tetramethylrhodamine isothiocyanate conjugates. After the cells were spun down on slides and fixed with methanol/acetic acid and formaldehyde, in situ hybridization with a biotinylated Y-chromosome-specific DNA probe was performed. The probe was detected with avidin-fluorescein isothiocyanate and the signal was amplified by consecutive incubation with biotinylated anti-avidin and avidin-fluorescein isothiocyanate. The membrane staining for various antigens remained undisturbed during the hybridization procedure and the Y probe discriminated almost completely between male and female cells. Therefore, this approach allowed us to determine the chimerism within different subpopulations of unseparated mononuclear cells after sex-mismatched bone marrow transplantation with a sensitivity of 98% and a specificity of 100%.

TaqI digestion reveals fractions of satellite DNAs on human chromosomes

Restriction endonuclease TaqI has been known as a nonbanding restriction endonuclease when it is used on fixed human chromosomes. However, a specific TaqI digestion can be obtained after varying experimental conditions such as concentration of enzyme, time of incubation, and volume of the final reaction mixture. This digestion consists of an extensive DNA loss in heterochromatin subregions of chromosomes 1, 9, 15, 16, and Y. These regions essentially coincide with those corresponding to the main chromosome locations of satellite II DNA, whose tandem repeated units contain many TaqI target sequences, and some satellite III DNA domains enriched in TaqI sites.

Sex chromosome marker: clinical significance and DNA characterization

Two patients are described with a virtually identical marker sex chromosome that was so small as to defy classification by conventional cytogenetic studies. DNA hybridization with Y probes allows classification into Y or non-Y, and in situ hybridization with X centromere specific sequences, into X or non-X. One patient was proven to have a Y fragment, and the second, an X fragment. DNA characterization is important since prognosis and clinical management depends on proper identification of the small marker sex chromosome.

Isolation of a Y chromosomal DNA sequence and its clinical application

A 4.6 kb long, Y-specific DNA fragment was isolated from a flow-sorted human Y chromosomal library, and its male specificity was confirmed by Southern blot analysis. The fragment, designated as pY-80, was proven with an in situ hybridization experiment to have originated from the Yp11.2-Ypter region. Its 2,808 bp section was sequenced. The polymerase chain reaction proceeded with oligonucleotides flanking a 666 bp PstI-EcoRI fragment of the sequence as primers and a male genomic DNA as a template, but not with a female genomic DNA. Preliminary tests of samples of various sources successfully detected the Y-specific fragment in male-derived samples, including mouth wash, single hair roots, urinary epithelial cells, dried blood spots and amniotic fluid cells.

Gastric endocrine cells share a clonal origin with other gut cell lineages

There has been considerable debate about the ontological origin of gut endocrine cells as being either from the neural crest (or primitive epiblast) or from the endodermal stem cell. We have attempted to define the ontological origin of endocrine cells by applying an experimental system that uses a marker to identify one of the two phenotypes present in chimaeric mice as suggested by Ponder et al. (1985). This study involved two separate experiments. The first made use of the unique staining properties of Dolichos biflorus agglutinin (DBA), a lectin that binds to the N-acetyl galactosamine sugar residues present on the surface of C57Bl mouse gut, but absent from RoRIII mouse gut, in C57Bl----RoIII mouse chimaeras at the ultrastructural level. A four-stage procedure for staining at the EM level was developed. Although mature villous endocrine cells stained for DBA, immature endocrine cells did not, either in the positive crypts of chimaeric mouse gut or in gut from C57Bl positive controls. Thus a second marker was chosen. This experiment combined immunocytochemistry (to identify gastric antral gastrin cells chosen as a representative neuroendocrine cell) with in situ DNA hybridization for the mouse male chromosome repeat sequence PY 353 (to identify XY cells) in XX----XY chimaeric mice. This study showed that the sex chromosomal pattern in the gastrin cells parallels that of other cells in the same gastric gland and therefore are clonal with them. This suggests that gut endocrine cells share a common stem cell with other epithelial cell lineages in the antrum and are endodermally derived.

[Sex determination in blood stains through identification of Y-chromatin: medico-legal application]

The Y-chromatin is visualized in human interphase nuclei, corresponding to the distal portion of the Y-chromosome, which shows marked fluorescence after staining with quinacrine. This report describes the results of sex determination on blood smears fixed in methanol and blood stains left at room temperature for 13 weeks (1st report), and for 10 months (2nd report). Blind trials showed that a reliable sex determination of blood stains on glass left for at least six months is possible. The application of this method in forensic practice is discussed.