Ann C. Chandley

A Y chromosome gene family with RNA-binding protein homology : Candidates for the azoospermia factor AZF controlling human spermatogenesis

We have previously mapped the human azoospermia factor to a deletion in Y chromosome interval 6 (subinterval XII-XIV). We now report the isolation and characterization of a gene family located within this deletion. Analysis of the predicted protein products suggests a possible role in RNA processing or translational control during early spermatogenesis. The Y chromosome RNA recognition motif (YRRM) family includes a minimum of three members expressed specifically in the testis. Interphase in situ results and Southern blot analysis indicate that several further YRRM sequences map within interval 6. Several mammalian species show Y chromosome conservation of YRRM sequences. We have detected deletions of YRRM sequences in two oligospermic patients with no previously detectable mutation.

Meiosis in the male mouse. An autoradiographic investigation

Meiosis in the male mouse has been studied autoradiographically in air-dried preparations. Information has been obtained on the relative rates of DNA synthesis and the lengths of the S-periods in spermatogonia and spermatocytes. The average rate of synthesis in the spermatocyte is lower, and the S-period is of longer duration than the preceding spermatogonial generations. The labelling pattern of the sex-chromosomes and autosomes observed at diakinesis and metaphase II in cells labelled at the spermatocyte S-period appears to be similar to that found in cells labelled during the spermatogonial S-periods. Replication in the autosomes commences before the sex-chromosomes. Late replicating autosomal centric regions show a marked degree of asynchrony in labelling both between and within bivalents. The Y chromosome starts and finishes replication later than the X. There is a short, late-replicating, segment of the X in the vicinity of the centromere. There is a short, early-replicating segment of the Y in the vicinity of the centromere which may represent the euchromatic short arm. The X and Y appear to associate at diakinesis by the distal ends of their long arms.

Radiation-initiated DNA synthesis in spermatogenic cells of the mouse

Abstract 1. 1. “Unscheduled” DNA synthesis has been demonstrated in spermatogenic cells of the mouse following high and low doses of UV and high doses of X-rays, using autoradiographic techniques. 2. 2. A small amount of “natural” DNA synthesis also occurs at the zygotene/pachytene stages of meiotic prophase. 3. 3. Little or no “unscheduled” DNA synthesis can be detected in testicular spermatozoa, but spermatogonia, spermatocytes and spermatids show varying levels of synthesis. 4. 4. Maximum levels of “unscheduled” DNA synthesis are found in late-zygotene/early pachytene spermatocytes, the cell-stage showing some “natural” DNA synthesis in the controls. 5. 5. The results are discussed in terms of a general “repair” system operating in spermatogenic cells.

“Unscheduled” DNA synthesis in human germ cells following UV irradiation

Abstract By the use of autoradiographic techniques, “unscheduled” DNA synthesis has been demonstrated in human germ cells following irradiation with high doses of UV light. All spermatogenic stages in the testis appear to perform UV-induced “unscheduled synthesis” with the exception of spermatozoa. Maximum levels of “unscheduled” DNA synthesis are found in late zygotene/ early pachytene spermatocytes. In unirradiated control cultures, some nuclear DNA synthesis is taking place at the late zygotene/early pachytene stage of meiotic phrophase.

Studies on oogenesis in Drosophila melanogaster with 3H-thymidine label

Abstract Autoradiography of ovaries fixed 30 min after injection of Drosophila females with 3H-thymidine reveals that the labelled germ cells are confined to the anterior region of the germarium. The labelled cells fall into groups of 1, 2, 4, 8 and 16 which presumably correspond to successive generations of oogonia. The amount of label in 2-, 4- and 8-cell groups is proportional to the number of cells in a group, which indicates that the rate of DNA-synthesis is the same over successive oogonial generations. In the case of 16-cell cysts the amount of label appears to be slightly lower than that expected immediately after injection by comparison with the various oogonial cysts, and may indicate a slower rate of synthesis in the oocyte S-period. The early stages of development of the oocyte were followed in material fixed at 3, 6, 12, 24, 48 and 72 hr after labelling. The total grain count over a cyst of 16 cells indicates the labelled oogonial generation from which it has differentiated. Cysts of 16 cells with maximum label (i.e. labelled at the meiotic S-period) first appear in the middle of the germarium (Region 2) at 24 hr. The first labelled Stage 1 egg-chambers (labelled at the meiotic S-period) were seen at 48 hr in the posterior region of the germarium. More were found at 72 hr, when the first Stage 2 egg chambers were found.

Centromere Staining at Meiosis in Man

SummaryA recently-developed barium hydroxide/saline/giemsa technique has been used to demonstrate constitutive heterochromatin in human male meiotic chromosomes. The technique aids bivalent identification at diakinesis and has been applied to an analysis of meiosis in two patients with normal karyotypes and two translocation heterozygotes.ZusammenfassungMit Hilfe der kürzlich entwickelten Bariumhydroxyd/Kochsalz/Giemsa-Technik wurde konstitutives Heterochromatin an männlichen Meiosechromosomen des Menschen gefärbt. Die Methode ermöglicht die Identifizierung der “bivalents” in der Diakinese. Sie wurde zur Meiose-Analyse verwendet bei 2 Patienten mit normalem Karyotyp und 2 Translokations-Heterozygoten.

Characterization of the domestic horse (Equus caballus) karyotype using G-and C-banding techniques

Giemsa banding techniques have been used to identify the chromosomes of the domestic horse.

Cytological evidence that the Sxr fragment of XY,Sxr mice pairs homologously at meiotic prophase with the proximal testis-determining region

Self-pairing of the Y chromosome at prophase of meiosis in XY,Sxr male mice appears to take place in many cells to the exclusion of pairing between the Y and the X. This phenomenon offers an explanation for the high level of X-Y separation seen in these males at prophase of meiosis, additional separations being evident, however, when metaphase I (MI) cells are examined. A minority of prophase cells show the Y paired both autologously and with a sub-terminal region of the X which could be the normal pairing region. The balloon-like configurations observed when self-pairing occurs suggest that the distal Sxr fragment is inverted on the Y chromosome of Sxr carrier males in relation to the normal proximal testis-determining (Td)-containing region.