Human Molecular Genetics, 2002, Vol. 11, No. 24 3047-3053
© 2002 Oxford University Press
A novel gene, Pog, is necessary for primordial germ cell proliferation in the mouse and underlies the germ cell deficient mutation, gcd
1Department of Obstetrics and Gynecology and 2Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, USA, 3University of Texas, MD Anderson Cancer Center, Houston, TX, USA and 4University of Medicine and Dentistry of New Jersey, Piscataway, NJ, USA
Received July 18, 2002; Accepted September 13, 2002
DDBL/EMBL/GenBank accession nos. AF513619 and AF513620
 |
ABSTRACT |
|---|
 TOP ABSTRACT INTRODUCTIONRESULTS AND DISCUSSIONMATERIALS AND METHODSREFERENCES |
|---|
Primordial germ cells (PGCs) are the precursor of the germ cells in adult gonads. They arise extra-gonadally and migrate through somatic tissues to the presumptive genital ridges, where they proliferate and differentiate into oogonia or spermatogonia cells. Abnormalities in this developmental process can cause embryonic depletion of germ cells leading to infertility in the adult. We report here that the mouse gcd (germ cell deficient) mutant phenotype, characterized by reduced numbers of PGCs and adult sterility, is due to reduced PGC proliferation rather than aberrant migration and is caused by the partial deletion of a single novel gene, Pog (proliferation of germ cells). Pog is critical for normal PGC proliferation, starting between 9.5 and 10.25 dpc when germ cells begin to migrate to the developing genital ridge. Deletion of Pog is also accompanied by reduced embryonic body weight and, on some genetic backgrounds, embryonic lethality. Thus, in addition to being necessary for PGC proliferation, Pog may have a wider significance in early embryonic development.
|
INTRODUCTION |
|---|
|
TOPABSTRACTINTRODUCTIONRESULTS AND DISCUSSIONMATERIALS AND METHODSREFERENCES |
|---|
Primordial germ cells (PGCs) are the founder cell population of the gametes. In the mouse they are distinguishable at 7.5 dpc (days post coitum) as a small pool of cells having high alkaline phosphatase expression (1–4). They emigrate from the hindgut epithelium at 9.5 dpc through the dorsal mesentery (10.5 dpc) and into the developing genital ridges by 11.5 dpc (5–7). There they continue to proliferate until 13.5 dpc when in the male they arrest at mitosis and in the female they enter meiosis. The germ cell deficient (gcd) mutation (8) is a recessive, transgenic insertional mutation in which there is a drastic reduction of PGCs in the developing genital ridge, resulting in male and female infertility in the adult. The male phenotype of a vacuolated testis, with very few functional tubules, is similar to the azoospermia phenotype seen in infertile human males. The female phenotype of rapid follicular depletion resembles the premature ovarian failure syndrome (POF) seen in infertile females (9,10). Thus, determining the exact defect in the gcd mouse and its underlying genetic basis could have considerable impact on these surprisingly common clinical syndromes. We report here that the gcd phenotype is due to the deletion of a single novel gene, Pog ( proliferation of germ cells) which encodes a protein with a plant homeodomain (PHD) motif at its C terminus (11). Pog is critical for normal PGC proliferation, starting between 9.5 and 10.25 dpc when germ cells begin to migrate into the developing genital ridge. It does not affect their normal migration pattern. Deletion of Pog is also accompanied by reduced embryonic body weight and, on some genetic backgrounds, embryonic lethality. Thus, in addition to being necessary for PGC proliferation, Pog may have a wider significance in early embryonic development.
|
RESULTS AND DISCUSSION |
|---|
|
TOPABSTRACTINTRODUCTIONRESULTS AND DISCUSSIONMATERIALS AND METHODSREFERENCES |
|---|
Total PGC numbers in 8.5 and 9.5 dpc gcd embryos were estimated after whole mount alkaline phosphatase (AP) staining. No difference in PGC number or migration pattern was seen between gcd/gcd and gcd/+ or +/+ littermates at these stages (Fig. 1A). 10.25–10.5 dpc embryos were then fully sectioned, stained for AP and the number and position of PGC's in each section recorded. It was found that the germ cell deficiency could be detected at 10.25 dpc with gcd/gcd homozygotes having approximately one third the number of PCGs found in their normal gcd/+ or +/+ littermates (Fig. 1A–C). Homozygous gcd/gcd PGCs were only found in the developing genital ridge or in the dorsal mesentery near the genital ridge (5,7). No PGCs were found in any other tissues indicating that germ cell migration was following the normal pathway. Further, PGCs from gcd/gcd and +/+ 11.5 dpc embryos were found to have colonized the genital ridge indicating that there was no temporal change in the migration pattern (Fig. 1B e and f).
|
In this analysis, gcd/gcd homozygotes were generated by intercrossing (C57BL/6xFVB)F1 gcd/+ heterozygotes and all genotypes were obtained in the expected Mendelian ratio. In contrast, on a predominantly C57BL/6 genetic background (N8), it was found that although gcd/gcd mice could be obtained in normal numbers up to 9.5 dpc they were virtually absent by 10.5 dpc. It was also noted that on the permissive C57BL6xFVB background, although normal numbers of homozygous gcd/gcd embryos were obtained, they were significantly smaller than their gcd/+ or +/+ littermates at 10.5 and 11.5 dpc (Fig. 1D and E). This weight difference was no longer manifest at birth.
Taken together, these data suggest that the germ cell deficiency is due to a defect in normal PGC proliferation, rather than migration, beginning between 9.5–10.25 dpc, just as the first PGCs begin to enter into the genital ridge. They also show that the development of the embryo proper is compromised by the gcd mutation at this point.
In order to identify and clone the gene responsible for the gcd phenotype, sequences flanking both ends of the transgenic insertion (
3.1 and 3.19) were obtained from a gcd/gcd genomic phage library. A single 200 kb BAC clone (RPCI253D2) spanning both breakpoints was subsequently identified and its gene content estimated by shotgun sample sequencing (Fig. 2A). Altogether 360 subclones were sequenced, five of which matched EST records in the database corresponding to two distinct genes, Vrk2 (mouse ortholog of the human vaccinia virus related kinase 2, VRK2) a serine/threonine kinase (12,13) and a novel gene provisionally termed Pog. The insertion of the goat ß-globin transgene caused an 
150 kb deletion of mouse genomic DNA removing exons 2–11 of Vrk2 and exons 4–14 of Pog (Fig. 2A). Vrk2 and Pog are transcribed in opposite orientations, their last exons, (exon 11 of Vrk2 and exon 14 of Pog) overlap and are transcribed off complementary DNA strands. Northern analysis and RT–PCR indicate that both genes have a widespread expression pattern, including 10.5 dpc embryos and adult gonads (Fig. 2B, ref. 13).
|
Mouse Pog encodes a protein of 375 amino acids and contains a plant homeodomain (PHD) zinc-finger motif (C4HC3 consensus sequence) at the C-terminus (11) (Fig. 2C). A blast search of GenBank revealed a human cDNA sequence with 77% nucleotide identity to mouse Pog (Ac. No. AK001197). Analysis of the human genomic sequence showed identical intron–exon organization and orientation of mouse/human Pog/POG and Vrk2/VRK2 genes. The POG protein is well conserved between mouse and human, showing an overall 79% amino acid identity. Drosophila melanogaster and Arabidopsis thaliana each has a protein sequence with weak similarity to mouse and human POG (Fig. 2C). The similarity is not confined to the PHD domain although it is more prominent in this region.
To test whether deletion of Vrk2 was responsible for the gcd phenotype, BAC rescue was performed. BAC 253D2, which contains the complete mouse Vrk2 coding sequence and upstream promotor/control elements, was microinjected into fertilized FVB/N eggs. Expression of the resulting transgene in the adult gonads was confirmed by RT–PCR using a polymorphism in the 3' UTR of Vrk2 to distinguish endogenous (FVB/N) from transgenic (C57BL/6) expression. The Vrk2 transgene was introduced into the homozygous gcd/gcd mouse background using a standard mating scheme and the histology of adult (4–6 week) testis and ovaries was examined. The phenotype of the transgenic Vrk2, gcd/gcd males and females was indistinguishable from that of the non-transgenic gcd/gcd littermates (data not show). This lack of complementation suggested that Vrk2 does not underlie the gcd phenotype and implied a role for Pog.
We examined the biological role of Pog using an insertional gene targeting approach developed by Zheng et al. (14,15). As shown in Figure 3, homologous recombination leads to double stranded gap repair, duplication of Pog exons 9–13 and the insertion of the vector backbone DNA between the duplicated segments. The C-terminus of POG, which contains the putative PHD domain, was thus disrupted.
|
Pog+/Pog- targeted males (where Pog- is a targeted allele) were crossed to gcd/+ females to produce compound heterozygotes, or intercrossed to Pog+/Pog- females to produce Pog-/Pog- null mice. Transcription of Pog was checked in the gonads and spleen of the resulting homozygous Pog-/Pog- targeted mice using RT–PCR and primers specific for the 5' and the 3' ends of the gene. No transcription could be detected, suggesting that disruption of the 3' end of the transcript has led to mRNA instability and degradation. As expected, the expression of mouse Vrk2 mRNA was not affected and could be detected in Pog-/Pog- gonad RNA (data not shown).
A histological examination of 4 week adult gcd/gcd, gcd/Pog- and Pog-/Pog- gonads (Fig. 4) showed that they had virtually identical sterility phenotypes with abnormal testis and ovaries, characteristic of the original gcd/gcd mutation (8). Testes were one third normal size with over 90% of the tubules containing vacuolated Sertoli cells but no developing germ cells (Fig. 4A–D). It is interesting to note that in both gcd/gcd and Pog-/Pog- adult males there is some degree of re-population of the seminiferous tubules by germ cells (Lu and Bishop, unpublished data). In the affected female, the ovary was extremely small and the uterine horns were pale and thin. Very few developing follicles were seen compared to Pog+/Pog+ or Pog+/Pog- controls (Fig. 4E–G). In addition, germ cell deficiency was confirmed in 10.5 dpc Pog-/gcd embryonic gonads (Fig. 5). Significantly, the latter embryos contain an intact copy of the Vrk2 gene, but nevertheless manifest the mutant germ cell depletion phenotype. No histological abnormalities could be detected in the Pog-/Pog- lung, heart, spleen, kidney or liver (data not shown). Similar to the gcd/gcd crosses, Pog-/Pog- and gcd/Pog- embryonic lethality was seen on pure 129/Sv and (129/SvxB6)F1 backgrounds. In these experiments Pog-/Pog- and gcd/Pog- mice were generated (in normal numbers) on a mixed (129/SvxFVB)F1 and (129/svxFVB)xB6 background, respectively.
|
|
These data demonstrate that it is the deletion of the Pog gene alone which is responsible for the germ cell deficiency, reduced embryonic body weight and, on some genetic backgrounds, embryonic lethality. Deletion of Vrk2 in the original gcd mice does not appear to contribute to the phenotype as gonadal dysfunction appears identical between Pog-/Pog- and gcd/Pog- mice even though the latter express Vrk2. Any somatic function of Vrk2 can presumably be replaced by redundancy within the protein kinase family (12). Formal proof that Vrk2 does not play a role in the phenotype could be evaluated in future knockout experiments. The experimental data obtained here show that Pog is not necessary for correct germ cell migration, but is critical for proliferation of PGCs beginning between 9.5–10.25 dpc. It is at this point that embryos show lower body weight (or embryonic lethality occurs) suggesting that Pog also effects the development of the somatic tissues.
Only a few genes are known to specifically affect PGC proliferation in vivo. TGF beta signaling molecules, in particular, BMP4 and BMP8b (16) and their downstream signal mediators SMAD1 and SMAD5 (17,18), all affect PGC development to various degrees, but there is no evidence that POG is part of this pathway. Decreased PGC migration and reduced proliferation are also associated with the W (white spotting) and Sl (Steel) mutants which involve the c-Kit, receptor kinase gene and its ligand Scf (stem cell factor) respectively (19). Unlike the W and Sl mutations Pog-/Pog- mice do not show defects in hematopoiesis or melanocyte development. The gcd phenotype is quite similar to that of Tiar-/Tiar- mice (20). Both have reduced numbers of PGCs as early as 11.5 dpc and both show partial embryonic lethality. TIAR is an RNA binding protein involved in apoptosis (21,22). Our preliminary data using a TUNEL assay indicates that apoptosis is not involved in the gcd phenotype indicating that POG acts through a different mechanism.
As yet, is not yet known how the Pog gene exerts its effect on PGC proliferation. An analysis of the protein structure suggests that it is an intracellular protein encoding a PHD domain at the C-terminus. This motif is believed to be important in the regulation of gene expression, through interaction with other proteins and subsequent modulation of chromatin structure.
In summary, we have identified a novel gene, Pog, the deletion of which is responsible for the phenotypic lack of germ cells seen in the gcd mouse mutant. Pog is critical for normal PGC proliferation beginning at the time of their entry into the developing genital ridge, at 9.5–10.25 dpc. Beginning at the same time point, Pog null mice also show reduced embryonic body weight or lethality depending on genetic background suggesting that it may also play a wider role in embryogenesis. Identification of the pathway through which the POG protein acts during PGC proliferation should provide a better understanding of the biology of early germ cell development.
|
MATERIALS AND METHODS |
|---|
|
TOPABSTRACTINTRODUCTIONRESULTS AND DISCUSSIONMATERIALS AND METHODSREFERENCES |
|---|
Alkaline phosphatase staining of PGC's
The morning vaginal plugs were found was taken as 0.5 dpc. Embryos were dissected from the deciduae and DNA extracted from the yolk sac or the embryo proper was used for genotyping by PCR. Embryos were fixed in 4% paraformaldehyde for 2 h at 4°C. For whole mount staining, the embryos were processed as described (17) and stained with Fast Red (Sigma) (23). For staining sections, the embryos were fixed, dehydrated, embedded in Paraplast X-tra (Fisher) at 54°C and mounted on silanated slides (Sigma). Sections were dewaxed in Histo-Clear (National Diagnostics, GA) rehydrated and stained with Fast Red.
Gene targeting
A 5.3 kb plasmid was isolated from a mouse genomic DNA library (14) using the Pog cDNA as probe. It cut with HpaI and religated to generate a 300 bp ‘gapped’ clone which was used for electroporation of AB1 ES cells. ES cells were selected with 0.35 mg/ml G418 and PCR was used to screen for targeted clones. The primers used for amplifying the 3 kb fragment in the screening were P3527, 5'-AGAAGAGCAGAATAGCAGTTGTT-3' (from the targeting vector) and gap1 5'-ATGCTGCTGCTCACTTCTGA-3' (from the deleted 300 bp fragment). The primers used for amplifying the 2 kb fragment were Bzp1, 5'-CGGAAGAGCGCCCAATAC-3' (from the targeting vector), and gap2, 5'-TCAGAAGTGAGCAGCAGCAT-3'. (from the deleted 300 bp fragment). Pog+/Pog- ES clones were then injected into C57BL/6 blastocysts, transferred to pseudopregnant females and resulting germ line chimeras identified by crossing to C57BL/6 females.
Maintenance of gcd mice and Pog knockout mice
gcd mice, originally obtained on a mixed (C57BL/6xCBA/H) F1 background, were subsequently backcrossed to C57BL/6 for 8 generations in our facilities. Homozygous gcd/gcd mice were obtained by intercrossing heterozygous C57BL/6 gcd/+ mice and heterozygous gcd/+ (FVB/NXC57BL/6)F1's. Pog+/Pog- targeted mice were maintained on a 129/Sv background. Pog-/Pog- mice were obtained by intercrossing 129/sv Pog+/Pog- or 129/SvxFVB/N)F1 heterozygotes.
Genotyping
Mouse ear or tail pieces were digested in 50 µl of digestion buffer (10 mmol/l Tris-HCl, pH 9.0, 50 mmol/l KCl, 1.5 mmol/l MgCl2, 0.1% Triton X-100, 0.45% IGEPAL, 0.8 mg/ml proteinase K) at 55°C for 4 h to overnight. It was heated at 94°C for 10 minutes, centifuged at 10 000 g for 5 min and the supernatant used for PCR. Primers for amplification of goat ß-globin DNA were gcd/intF, 5-CCTGTGGAACCACACC TTG-3' and gcd/intR 5'-TGGTGTCTGTTTGTGTAGCTG-3'. Primers for amplification of the deleted region in gcd: gcdF1 5'-CTTTGGACTGAGCTACTGCCGTTAAC-3' and gcdR1 5'-GTAAGTTTGTGAAGGACAGCGATAG-3'. Primers for amplification of targeted allele in Pog knockout mice: Type1 5'-CCACAACAACTTGTATGCGTC-3' and Bzp1 as describe in ‘gene targeting’ section.
Histology
Tissue samples were fixed in Bouin's Solution (Sigma) and processed for routine histology. 8 µl sections were cut and stained with haematoxylin and eosin.
|
ACKNOWLEDGEMENTS |
|---|
We would like to thank Helen Martinez for excellent technical assistance and Dr Jan Rohozinski for critical reading of the manuscript. We thank Dr Peter J. Donovan for his comments and suggestions. This research was supported by NIH grant P01 HD36289 to C.E.B.
|
FOOTNOTES |
|---|
* To whom correspondence should be addressed at: Department of Obstetrics and Gynecology, Baylor College of Medicine, 6550 Fannin Street (#880), Houston, TX 77030, USA. Tel: +1 7137988221; Fax: +1 7137985074; Email: bishop{at}bcm.tmc.edu
The authors wish it to be known that, in their opinion, these two authors should be considered as joint First Authors.
|
REFERENCES |
|---|
|
TOPABSTRACTINTRODUCTIONRESULTS AND DISCUSSIONMATERIALS AND METHODSREFERENCES |
|---|
1 Chiquoine, A.D. (1954) The identification, origin and migration of the primordial germ cells in the mouse embryo. Anat. Rec., 118, 135–146.[Medline]
2
Ginsburg, M., Snow, M.H. and McLaren, A. (1990) Primordial germ cells in the mouse embryo during gastrulation. Development, 110, 521–528.
3
Hahnel, A.C., Rappolee, D.A., Millan, J.L., Manes, T., Ziomek, C.A., Theodosiou, N.G., Werb, Z., Pedersen, R.A. and Schultz, G.A. (1990) Two alkaline phosphatase genes are expressed during early development in the mouse embryo. Development, 110, 555–564.
4 MacGregor, G.R., Zambrowicz, B.P. and Soriano, P. (1995) Tissue non-specific alkaline phosphatase is expressed in both embryonic and extraembryonic lineages during mouse embryogenesis but is not required for migration of primordial germ cells. Development, 121, 1487–1496.[Abstract]
5 Clark, J.M. and Eddy, E.M. (1975) Fine structural observations on the origin and associations of primordial germ cells of the mouse. Dev. Biol., 47, 136–155.[Web of Science][Medline]
6 Starz-Gaiano, M. and Lehmann, R. (2001) Moving towards the next generation. Mech. Dev., 105, 5–18.[Web of Science][Medline]
7 Tam, P.P. and Snow, M.H. (1981) Proliferation and migration of primordial germ cells during compensatory growth in mouse embryos. J. Embryol. Exp. Morphol., 64, 133–147.[Web of Science][Medline]
8
Pellas, T.C., Ramachandran, B., Duncan, M., Pan, S.S., Marone, M. and Chada, K. (1991) Germ-cell deficient (gcd), an insertional mutation manifested as infertility in transgenic mice. Proc. Natl Acad. Sci. USA, 88, 8787–8791.
9 Duncan, M., Cummings, L. and Chada, K. (1993) Germ cell deficient (gcd) mouse as a model of premature ovarian failure. Biol. Reprod., 49, 221–227.[Abstract]
10 Duncan, M.K. and Chada, K.K. (1993) Incidence of tubulostromal adenoma of the ovary in aged germ cell-deficient mice. J. Comp. Pathol., 109, 13–19.[Web of Science][Medline]
11 Aasland, R., Gibson, T.J. and Stewart, A.F. (1995) The PHD finger: implications for chromatin-mediated transcriptional regulation. Trends Biochem. Sci., 20, 56–59.[Web of Science][Medline]
12
Hanks, S.K., Quinn, A.M. and Hunter, T. (1988) The protein kinase family: Conserved features and deduced phylogeny of the catalytic domains. Science, 241, 42–52.
13 Nezu, J., Oku, A., Jones, M.H. and Shimane, M. (1997) Identification of two novel human putative serine/threonine kinases, VRK1 and VRK2, with structural similarity to vaccinia virus B1R kinase. Genomics, 45, 327–331.[Web of Science][Medline]
14
Zheng, B., Mills, A.A. and Bradley, A. (1999) A system for rapid generation of coat color-tagged knockouts and defined chromosomal rearrangements in mice. Nucleic Acids Res., 27, 2354–2360.
15 Zheng, B., Sage, M., Cai, W.W., Thompson, D.M., Tavsanli, B.C., Cheah, Y.C. and Bradley, A. (1999) Engineering a mouse balancer chromosome. Nat. Genet., 22, 375–378.[Web of Science][Medline]
16
Ying, Y., Liu, X.M., Marble, A., Lawson, K.A. and Zhao, G.Q. (2000) Requirement of Bmp8b for the generation of primordial germ cells in the mouse. Mol. Endocrinol., 14, 1053–1063.
17 Chang, H. and Matzuk, M.M. (2001) Smad5 is required for mouse primordial germ cell development. Mech. Dev., 104, 61–67.[Web of Science][Medline]
18
Tremblay, K.D., Dunn, N.R. and Robertson, E.J. (2001) Mouse embryos lacking Smad1 signals display defects in extra-embryonic tissues and germ cell formation. Development, 128, 3609–3621.
19 Kierszenbaum, A.L. and Tres, L.L. (2001) Primordial germ cell–somatic cell partnership: a balancing cell signaling act. Mol. Reprod. Dev., 60, 277–280.[Web of Science][Medline]
20
Beck, A.R., Miller, I.J., Anderson, P. and Streuli, M. (1998) RNA-binding protein TIAR is essential for primordial germ cell development. Proc. Natl Acad. Sci. USA, 95, 2331–2336.
21
Gueydan, C., Droogmans, L., Chalon, P., Huez, G., Caput, D. and Kruys, V. (1999) Identification of TIAR as a protein binding to the translational regulatory AU-rich element of tumor necrosis factor alpha mRNA. J. Biol. Chem., 274, 2322–2326.
22
Kawakami, A., Tian, Q., Duan, X., Streuli, M., Schlossman, S.F. and Anderson, P. (1992) Identification and functional characterization of a TIA-1-related nucleolysin. Proc. Natl Acad. Sci. USA, 89, 8681–8685.
23 Donovan, P.J., Stott, D., Cairns, L.A., Heasman, J. and Wylie, C.C. (1986) Migratory and postmigratory mouse primordial germ cells behave differently in culture. Cell, 44, 831–838.[Web of Science][Medline]
CiteULike 
Connotea 
Del.icio.us What's this?
This article has been cited by other articles:
|
|
 |
|
  D. Jamsai, D. M Bianco, S. J Smith, D. J Merriner, J. D Ly-Huynh, A. Herlihy, B. Niranjan, G. M Gibbs, and M. K O'Bryan Characterization of gametogenetin 1 (GGN1) and its potential role in male fertility through the interaction with the ion channel regulator, cysteine-rich secretory protein 2 (CRISP2) in the sperm tail Reproduction, June 1, 2008; 135(6): 751 - 759. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 K.R. Barnett, C. Schilling, C.R. Greenfeld, D. Tomic, and J.A. Flaws Ovarian follicle development and transgenic mouse models Hum. Reprod. Update, September 1, 2006; 12(5): 537 - 555. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 T. Taniguchi and A. D. D'Andrea Molecular pathogenesis of Fanconi anemia: recent progress Blood, June 1, 2006; 107(11): 4223 - 4233. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
S. A. Pangas and A. Rajkovic Transcriptional regulation of early oogenesis: in search of masters Hum. Reprod. Update, January 1, 2006; 12(1): 65 - 76. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 D. Baron, R. Houlgatte, A. Fostier, and Y. Guiguen Large-Scale Temporal Gene Expression Profiling During Gonadal Differentiation and Early Gametogenesis in Rainbow Trout Biol Reprod, November 1, 2005; 73(5): 959 - 966. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
M. De Felici, M.L. Scaldaferri, M. Lobascio, S. Iona, V. Nazzicone, F.G. Klinger, and D. Farini Experimental approaches to the study of primordial germ cell lineage and proliferation Hum. Reprod. Update, May 1, 2004; 10(3): 197 - 206. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
T. Takahashi, H. Tanaka, N. Iguchi, K. Kitamura, Y. Chen, M. Maekawa, H. Nishimura, H. Ohta, Y. Miyagawa, K. Matsumiya, et al. Rosbin: A Novel Homeobox-Like Protein Gene Expressed Exclusively in Round Spermatids Biol Reprod, May 1, 2004; 70(5): 1485 - 1492. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 R. J. Nichols and P. Traktman Characterization of Three Paralogous Members of the Mammalian Vaccinia Related Kinase Family J. Biol. Chem., February 27, 2004; 279(9): 7934 - 7946. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
F. W. Atchison and A. R. Means Spermatogonial Depletion in Adult Pin1-Deficient Mice Biol Reprod, December 1, 2003; 69(6): 1989 - 1997. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
J. O. Ward, L. G. Reinholdt, S. A. Hartford, L. A. Wilson, R. J. Munroe, K. J. Schimenti, B. J. Libby, M. O'Brien, J. K. Pendola, J. Eppig, et al. Toward the Genetics of Mammalian Reproduction: Induction and Mapping of Gametogenesis Mutants in Mice Biol Reprod, November 1, 2003; 69(5): 1615 - 1625. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 J. C.Y. Wong, N. Alon, C. Mckerlie, J. R. Huang, M. S. Meyn, and M. Buchwald Targeted disruption of exons 1 to 6 of the Fanconi Anemia group A gene leads to growth retardation, strain-specific microphthalmia, meiotic defects and primordial germ cell hypoplasia Hum. Mol. Genet., August 15, 2003; 12(16): 2063 - 2076. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 F. W. Atchison, B. Capel, and A. R. Means Pin1 regulates the timing of mammalian primordial germ cell proliferation Development, August 1, 2003; 130(15): 3579 - 3586. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
B. Lu and C. E. Bishop Late Onset of Spermatogenesis and Gain of Fertility in POG-Deficient Mice Indicate that POG Is Not Necessary for the Proliferation of Spermatogonia Biol Reprod, July 1, 2003; 69(1): 161 - 168. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
B. Lu and C. E. Bishop Mouse GGN1 and GGN3, Two Germ Cell-specific Proteins from the Single Gene Ggn, Interact with Mouse POG and Play a Role in Spermatogenesis J. Biol. Chem., April 25, 2003; 278(18): 16289 - 16296. [Abstract] [Full Text] [PDF]
|
|
| ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||