On the role of germ cells in planarian regeneration

Development ◽  
1980 ◽  
Vol 55 (1) ◽  
pp. 65-76
Author(s):  
V. Gremigni ◽  
C. Miceli ◽  
E. Picano
Keyword(s):  
Germ Cells ◽  
Dna Content ◽  
Somatic Cells ◽  
Diploid Male ◽  
Dna Amount ◽  
Male Germ Cells ◽  
Blastema Formation ◽  
Planarian Regeneration ◽  
Cytophotometric Analysis

Previous findings by our group have shown how primordial male germ cells take part in regenerative blastema formation in planarians by migrating to the wound. The role of these cells in rebuilding transected tissues has been investigated in a population of Dugesia lugubris s.l. which is particularly suited for our purpose. In fact, these planarians provide a clear karyological marker to distinguish diploid male germ cells (2n = 8) from tryploid embryonic or somatic cells (3n = 12). In this study we employed the cytophotometric analysis of the nuclear Feulgen-DNA content in order to distinguish non-replicating male germ cells from reserve and somatic cells. The Feulgen-DNA content in cells from the gonad-free caudal area was measured after complete regeneration. Most non-replicating cells (94–95%) were found to have a DNA amount typical of cells previously estimated as triploid. Some (5–6%) nuclei containing a DNA amount typical of cells previously estimated as diploid male gonia were also found. These findings seem to support the view that primordial male germ cells also participate in rebuilding somatic tissues according to the field influence they encounter during regeneration. The possibility that metaplasia (or cell transdifferentiation) may occur in planarians is finally discussed.

Evidence of male germ cell redifferentiation into female germ cells in planarian regeneration

Development ◽  
1982 ◽  
Vol 70 (1) ◽  
pp. 29-36
Author(s):  
V. Gremigni ◽  
M. Nigro ◽  
I. Puccinelli
Keyword(s):  
Germ Cells ◽  
Somatic Cells ◽  
The Body ◽  
Diploid Male ◽  
Female Gonad ◽  
Anterior Portion ◽  
Male Germ Cells ◽  
Blastema Formation ◽  
Planarian Regeneration ◽  
Undifferentiated Cells

The source and fate of blastema cells are important and still unresolved problems in planarian regeneration. In the present investigation we have attempted to obtain new evidence of cell dedifferentiation-redifferentiation by using a polyploid biotype of Dugesia lugubris s.1. This biotype is provided with a natural karyological marker which allows the discrimination of triploid embryonic and somatic cells from diploid male germ cells and from hexaploid female germ cells. Thanks to this cell mosaic we previously demonstrated that male germ cells take part in blastema formation and are then capable of redifferentiating into somatic cells. In the present investigation sexually mature specimens were transected behind the ovaries and the posterior stumps containing testes were allowed to regenerate the anterior portion of the body. Along with the usual hexaploid oocytes, a small percentage (3.2%) of tetraploid oocytes were produced from regenerated specimens provided with new ovaries. By contrast only hexaploid oocytes were produced from control untransected specimens. The tetraploid oocytes are interpreted as original diploid male germ cells which following the transection take part in blastema formation and then during regeneration redifferentiate into female germ cells thus doubling their chromosome number as usual for undifferentiated cells entering the female gonad in this biotype.

On the role of germ cells in planarian regeneration

Development ◽  
1980 ◽  
Vol 55 (1) ◽  
pp. 53-63
Author(s):  
V. Gremigni ◽  
C. Miceli ◽  
I. Puccinelli
Keyword(s):  
Chromosome Number ◽  
Germ Cells ◽  
Primordial Germ Cells ◽  
Karyological Analysis ◽  
Blastema Formation ◽  
Planarian Regeneration ◽  
Somatic Tissues ◽  
Caudal Area ◽  
Complete Regeneration

Specimens from a polyploid biotype of Dugesia lugubris s.l. were used to clarify the role and fate of germ cells during planarian regeneration. These specimens provide a useful karyological marker because embryonic and somatic cells (3n = 12) can be easily distinguished from male (2n = 8) and female (6n = 24) germ cells by their chromosome number. We succeed in demonstrating how primordial germ cells participate in blastema formation and take part in rebuilding somatic tissues. This evidence was obtained by cutting each planarian specimen twice at appropriate levels. The first aimed to induce primordial germ cells to migrate to the wound. The second cut was performed after complete regeneration and aimed to obtain a blastema from a cephalic or caudal area devoid of gonads. A karyological analysis of mitotic cells present in each blastema obtained after the second cut provided evidence that cells, originally belonging to the germ lines, are still present in somatic tissues even months after complete regeneration. The role of primordial germ cells in planarian regeneration was finally discussed in relation to the phenomenon of metaplasia or transdifferentiation.

scholarly journals Overexpression of peroxisomal testis-specific 1 protein induces germ cell apoptosis and leads to infertility in male mice

2011 ◽  
Vol 22 (10) ◽  
pp. 1766-1779 ◽  
Author(s):  
Karina Kaczmarek ◽  
Maja Studencka ◽  
Andreas Meinhardt ◽  
Krzysztof Wieczerzak ◽  
Sven Thoms ◽  
...  
Keyword(s):  
Cell Death ◽  
Germ Cell ◽  
Germ Cells ◽  
Specific Gene ◽  
Male Mice ◽  
Terminal Part ◽  
Male Germ Cells ◽  
Germ Cell Apoptosis ◽  
Induced Apoptosis

 Peroxisomal testis-specific 1 gene (Pxt1) is the only male germ cell–specific gene that encodes a peroxisomal protein known to date. To elucidate the role of Pxt1 in spermatogenesis, we generated transgenic mice expressing a c-MYC-PXT1 fusion protein under the control of the PGK2 promoter. Overexpression of Pxt1 resulted in induction of male germ cells’ apoptosis mainly in primary spermatocytes, finally leading to male infertility. This prompted us to analyze the proapoptotic character of mouse PXT1, which harbors a BH3-like domain in the N-terminal part. In different cell lines, the overexpression of PXT1 also resulted in a dramatic increase of apoptosis, whereas the deletion of the BH3-like domain significantly reduced cell death events, thereby confirming that the domain is functional and essential for the proapoptotic activity of PXT1. Moreover, we demonstrated that PXT1 interacts with apoptosis regulator BAT3, which, if overexpressed, can protect cells from the PXT1-induced apoptosis. The PXT1-BAT3 association leads to PXT1 relocation from the cytoplasm to the nucleus. In summary, we demonstrated that PXT1 induces apoptosis via the BH3-like domain and that this process is inhibited by BAT3.

scholarly journals Fertilization of mouse oocytes using somatic cells as male germ cells

2001 ◽  
Vol 3 (3) ◽  
pp. 205-211 ◽  
Author(s):  
Orly Lacham-Kaplan ◽  
Rob Daniels ◽  
Alan Trounson
Keyword(s):  
Germ Cells ◽  
Somatic Cells ◽  
Male Germ Cells ◽  
Mouse Oocytes

scholarly journals EPC1/TIP60-Mediated Histone Acetylation Facilitates Spermiogenesis in Mice

2017 ◽  
Vol 37 (19) ◽  
Author(s):  
Yixin Dong ◽  
Kyo-ichi Isono ◽  
Kazuyuki Ohbo ◽  
Takaho A. Endo ◽  
Osamu Ohara ◽  
...  
Keyword(s):  
Histone Acetylation ◽  
Germ Cells ◽  
Essential Role ◽  
Critical Role ◽  
Male Germ Cells ◽  
Genetic Ablation ◽  
Histone Hyperacetylation ◽  
Critical Components ◽  
Underlying Mechanisms

ABSTRACT Global histone hyperacetylation is suggested to play a critical role for replacement of histones by transition proteins and protamines to compact the genome during spermiogenesis. However, the underlying mechanisms for hyperacetylation-mediated histone replacement remains poorly understood. Here, we report that EPC1 and TIP60, two critical components of the mammalian nucleosome acetyltransferase of H4 (NuA4) complexes, are coexpressed in male germ cells. Strikingly, genetic ablation of either Epc1 or Tip60 disrupts hyperacetylation and impairs histone replacement, in turn causing aberrant spermatid development. Taking these observations together, we reveal an essential role of the NuA4 complexes for histone hyperacetylation and subsequent compaction of the spermatid genome.

scholarly journals Role of HP1β during spermatogenesis and DNA replication

2019 ◽  
Author(s):  
Vijaya Charaka ◽  
Anjana Tiwari ◽  
Raj K Pandita ◽  
Clayton R Hunt ◽  
Tej K. Pandita
Keyword(s):  
Dna Damage ◽  
Dna Replication ◽  
Germ Cells ◽  
Chromatin Condensation ◽  
Genomic Stability ◽  
Replication Forks ◽  
Chromatin Protein ◽  
Male Germ Cells ◽  
Chromatin Compaction

AbstractMaintaining genomic stability in a continually dividing cell population requires accurate DNA repair, especially in male germ cells. Repair and replication protein access to DNA, however, is complicated by chromatin compaction. The HP1β chromatin protein, encoded by Cbx1, is associated with chromatin condensation but its role in meiosis is not clear. To investigate the role of Cbx1 in male germ cells, we generated testis specific Cbx1 deficient transgenic mice by crossing Cbx1flox/flox (Cbx1f/f) mice with Stra8 Cre+/− mice. Loss of Cbx1 in testes adversely affected sperm maturation and Cbx1 deletion increased seminiferous tubule degeneration and basal level DNA damage., We observed that Cbx1−/− MEF cells displayed reduced resolution of stalled DNA replication forks as well as decreased fork restart, indicating defective DNA synthesis. Taken together, these results suggest that loss of Cbx1 in growing cells leads to DNA replication defects and associated DNA damage that impact cell survival.

scholarly journals The Central Role of Cadherins in Gonad Development, Reproduction and Fertility

2020 ◽  
Author(s):  
Rafał P. Piprek ◽  
Malgorzata Kloc ◽  
Paulina Mizia ◽  
Jacek Z. KUBIAK
Keyword(s):  
Germ Cells ◽  
Reproductive Tract ◽  
Primordial Germ Cells ◽  
Somatic Cells ◽  
Gonad Development ◽  
Female Reproductive Tract ◽  
Future Research ◽  
Corpora Lutea ◽  
Germline Development

Cadherins are a group of membrane proteins responsible for cell adhesion. They are crucial for cell sorting and recognition during the morphogenesis, but also play many other roles such as assuring tissue integrity and resistance to stretching, mechanotransduction, cell signaling, regulation of cell proliferation, apoptosis, survival, carcinogenesis, etc. Within the cadherin superfamily, the E- and N-cadherin have been especially well studied. They are involved in many aspects of sexual development and reproduction, such as germline development and gametogenesis, gonad development and functioning, and fertilization. E-cadherin is expressed in the primordial germ cells, (PGCs) and also participates in PGC migration to the developing gonads where they become enclosed by the N-cadherin-expressing somatic cells. The differential expression of cadherins is also responsible for the establishment of the testis or ovary structure. In the adult testes, the N-cadherin is responsible for the integrity of the seminiferous epithelium, regulation of sperm production, and the establishment of the blood-testis barrier. Sex hormones regulate the expression and turnover of N-cadherin influencing the course of spermatogenesis. In the adult ovaries, E- and N-cadherin assure the integrity of ovarian follicles and the formation of corpora lutea. Cadherins are expressed in the mature gametes, and facilitate the capacitation of sperm in the female reproductive tract, and gamete contact during fertilization. The germ cells and accompanying somatic cells express a series of different cadherins, however, their role in gonads and reproduction is still unknown. In this review, we show what is known and unknown about the role of cadherins in the germline and gonad development, and suggest the topics for future research.

Bone morphogenetic protein 8A plays a role in the maintenance of spermatogenesis and the integrity of the epididymis

Development ◽  
1998 ◽  
Vol 125 (6) ◽  
pp. 1103-1112 ◽  
Author(s):  
G.Q. Zhao ◽  
L. Liaw ◽  
B.L. Hogan
Keyword(s):  
Germ Cell ◽  
Germ Cells ◽  
Targeted Mutagenesis ◽  
Chromosome 4 ◽  
Female Reproduction ◽  
Cell Degeneration ◽  
Male Germ Cells ◽  
Morphogenetic Protein ◽  
Germ Cell Degeneration

The murine Bmp8a and Bmp8b genes are tightly linked on mouse chromosome 4 and have similar expression during reproduction. Previous studies have shown that targeted mutagenesis of Bmp8b causes male infertility due to germ cell degeneration. To investigate the function of Bmp8a, we have inactivated the gene by homologous recombination. Heterozygous and homozygous Bmp8a mutants reveal normal embryonic and postnatal development. Despite high levels of Bmp8a expression in the deciduum, homozygous mutant females have normal fertility, suggesting that the gene is not essential for female reproduction. Bmp8a and Bmp8b are expressed in similar patterns in male germ cells. Unlike homozygous Bmp8btm1 mutants, homozygous Bmp8atm1 males do not show obvious germ cell defects during the initiation of spermatogenesis. However, germ cell degeneration is observed in 47% of adult homozygous Bmp8atm1 males, establishing a role of Bmp8a in the maintenance of spermatogenesis. A small proportion of the mating homozygous Bmp8atm1 males also show degeneration of the epididymal epithelium, indicating a novel role for BMPs in the control of epididymal function.

scholarly journals Nodal Signaling Regulates the Entry into Meiosis in Fetal Germ Cells

Endocrinology ◽  
2012 ◽  
Vol 153 (5) ◽  
pp. 2466-2473 ◽  
Author(s):  
Benoit Souquet ◽  
Sophie Tourpin ◽  
Sébastien Messiaen ◽  
Delphine Moison ◽  
René Habert ◽  
...  
Keyword(s):  
Germ Cell ◽  
Germ Cells ◽  
Target Genes ◽  
Normal Male ◽  
Nodal Signaling ◽  
Male Germ Cells ◽  
Embryonic Germ Cells ◽  
Meiotic Inhibitors ◽  
First Time

The mechanisms regulating the entry into meiosis in mammalian germ cells remain incompletely understood. We investigated the involvement of the TGF-β family members in fetal germ cell meiosis initiation. Nodal, a member of the TGF-β family, and its target genes are precociously expressed in embryonic gonads and show sexual dimorphism in favor of the developing testis. Nodal receptor genes, Acvr2a and Acvr2b, Alk4, and Tdgf1/Cripto, were identified in male germ cells. Nodal itself, Tdgf1, and Lefty1 and Lefty2 are targets of Nodal signaling and were all found specifically expressed in male germ cells. To elucidate the role of this signaling pathway, activin-like kinases that mediate TGF-β/Nodal/activin signaling were inhibited in 11.5 d postconception testis in organotypic culture. Activin-like kinases inhibition disrupted normal male germ cell development and induced germ cell entry into meiosis such as that observed in female germ cells at the equivalent stage. Interestingly Stra8, the gatekeeper of the mitotic/meiotic switch, was induced independently of any change of either Cyp26b1 or Fgf9 expression, the two genes currently identified as testicular meiotic inhibitors. On the other hand, recombinant Nodal significantly dampened Stra8 expression and germ cell meiosis in cultured 11.5 d postconception ovaries. Our results allowed us to propose for the first time an autocrine role of Nodal during the development of germ cells and indicate that members of the TGB-β family may reinforce the male fate and prevent meiosis in embryonic germ cells.

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