scholarly journals A Selective Screen Reveals Discrete Functional Domains in Drosophila Nanos

Genetics ◽  
1999 ◽  
Vol 153 (4) ◽  
pp. 1825-1838 ◽  
Author(s):  
Gustavo Arrizabalaga ◽  
Ruth Lehmann

AbstractThe Drosophila protein Nanos encodes an evolutionarily conserved protein with two zinc finger motifs. In the embryo, Nanos protein function is required for establishment of the anterior-posterior body pattern and for the migration of primordial germ cells. During oogenesis, Nanos protein is involved in the establishment and maintenance of germ-line stem cells and the differentiation of oocyte precursor cells. To establish proper embryonic patterning, Nanos acts as a translational regulator of hunchback RNA. Nanos' targets for germ cell migration and development are not known. Here, we describe a selective genetic screen aimed at isolating new nanos alleles. The molecular and genetic analysis of 68 new alleles has allowed us to identify amino acids critical for nanos function. This analysis shows that the CCHC motifs, which coordinate two metal ions, are essential for all known functions of Nanos protein. Furthermore, a region C-terminal to the zinc fingers seems to constitute a novel functional domain within the Nanos protein. This “tail region” of Nanos is required for abdomen formation and germ cell migration, but not for oogenesis.

Development ◽  
1998 ◽  
Vol 125 (4) ◽  
pp. 667-678 ◽  
Author(s):  
L.A. Moore ◽  
H.T. Broihier ◽  
M. Van Doren ◽  
L.B. Lunsford ◽  
R. Lehmann

Gonadogenesis in the Drosophila embryo is a complex process involving numerous cellular migratory steps and cell-cell interactions. The mechanisms guiding germ cells to move through, recognize and adhere to specific cell types are poorly understood. In order to identify genes that are required for these processes, we have conducted an extensive mutagenesis of the third chromosome and screened for mutations disrupting germ cell migration at any point in embryonic development. Phenotypic analysis of these mutants demonstrates that germ cell migration can be broken down into discrete developmental steps, with each step requiring a specific set of genes. Many of these genes are involved in the development of gonadal mesoderm, the tissue that associates with germ cells to form the embryonic gonad. Moreover, mutations that we isolated affecting embryonic patterning as well as germ cell migration suggest that the origin of gonadal mesoderm lies within the eve domain of the developing mesoderm.


2005 ◽  
Vol 17 (5) ◽  
pp. 587 ◽  
Author(s):  
Yixiang Zhang ◽  
Xiumei Jin ◽  
Haitang Han ◽  
Zandong Li

Polychlorinated biphenyls cause developmental and physiological anomalies in the reproductive system. This study investigated the effects of 2,2′,5,5′-tetrachlorobiphenyl (PCB52), which can produce oestrogenic effects on the homeostasis of chicken primordial germ cells from the initial stage until completion of their settlement in the gonadal primordium. The blastoderm of chicken embryos was injected with 1 μL PCB52 (10 µmol/L) and oestradiol (100 µmol/L) before incubation, and the number of primordial germ cells was determined during their migration and development. The number of primordial germ cells in germinal crescents in PCB52-treated groups was slightly decreased (P = 0.068), but it was reduced significantly at stages 13–15 and 28–30 (P < 0.01, respectively) compared with controls. No obvious effects on primordial germ cell migration were observed with oestradiol treatments. The present results suggest that the influence of PCB52 on chicken primordial germ cell migration and proliferation may be via its toxic effect, not its oestrogen-mimicking effect, and provide information on the sensitivity of primordial germ cells to the direct action of PCB52.


Development ◽  
1999 ◽  
Vol 126 (8) ◽  
pp. 1655-1664 ◽  
Author(s):  
R. Anderson ◽  
R. Fassler ◽  
E. Georges-Labouesse ◽  
R.O. Hynes ◽  
B.L. Bader ◽  
...  

Primordial germ cells are the founder cells of the gametes. They are set aside at the initial stages of gastrulation in mammals, become embedded in the hind-gut endoderm, then actively migrate to the sites of gonad formation. The molecular basis of this migration is poorly understood. Here we sought to determine if members of the integrin family of cell surface receptors are required for primordial germ cell migration, as integrins have been implicated in the migration of several other motile cell types. We have established a line of mice which express green fluorescent protein in germline cells that has enabled us to efficiently purify primordial germ cells at different stages by flow cytometry. We have catalogued the spectrum of integrin subunit expression by primordial germ cells during and after migration, using flow cytometry, immunocytochemistry and RT-PCR. Through analysis of integrin beta1(−/−)--&gt;wild-type chimeras, we show that embryonic cells lacking beta1 integrins can enter the germline. However, integrin beta1(−/−) primordial germ cells do not colonize the gonad efficiently. Embryos with targeted deletion of integrin subunit alpha3, alpha6, or alphaV show no major defects in primordial germ cell migration. These results demonstrate a role for beta1-containing integrins in the development of the germline, although an equivalent role for * integrin subunit(s) has yet to be established.


Genetics ◽  
1996 ◽  
Vol 143 (3) ◽  
pp. 1231-1241 ◽  
Author(s):  
Nian Zhang ◽  
Jiaping Zhang ◽  
Yan Cheng ◽  
Ken Howard

Abstract We describe a novel genetic locus, wunen (wun), required for guidance of germ cell migration in early Drosophila development. Loss of wun function does not abolish movement but disrupts the orientation of the motion causing the germ cells to disperse even though their normal target, the somatic gonad, is well formed. We demonstrate that the product of this gene enables a signal to pass from the soma to the germ line and propose that the function of this signal is to selectively stabilize certain cytoplasmic extensions resulting in oriented movement. To characterize this guidance factor, we have mapped wun to within 100 kb of cloned DNA.


2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Jonathan J. Carver ◽  
Yuanfa He ◽  
Yong Zhu

AbstractAdamts9 (a disintegrin and metalloproteinase with a thrombospondin type 1 motif, member 9) is one of a few metalloproteinases structurally conserved from C. elegans to humans and is indispensable in germ cell migration in invertebrates. However, adamts9′s roles in germ cell migration in vertebrates has not been examined. In the present study, we found zygotic expression of adamts9 started around the germ ring stage and reached peak levels at 3 days post fertilization (dpf) in zebrafish. The migration of primordial germ cells (PGC) was completed within 24 hours (h) in wildtype siblings, while a delay in PGC migration was found at 15 and 24-h post-fertilization (hpf) in the Adamts9 knockout (KO). However, the delayed PGC migration in Adamts9 KO disappeared at 48 hpf. Our study suggests a conserved function of Adamts9 in germ cell migration among invertebrates and vertebrates. In addition, our results also suggest that Adamts9 is not essential for germ cell migration as reported in C. elegans, possibly due to expansion of Adamts family members and compensatory roles from other metalloproteinases in vertebrates. Further studies are required in order to elucidate the functions and mechanisms of metalloproteinases in germ cell migration and gonad formation in vertebrates.


2014 ◽  
Vol 2014 ◽  
pp. 1-9 ◽  
Author(s):  
Sittipon Intarapat ◽  
Orawan Satayalai

Gonadal development of quail embryos was examined histologically using histological and histochemical methods. In the present study, quail embryos were studied at various stages of incubation period based on phases of gonadogenesis. Germ cell migration was observed on day 3-4 but gonadal differentiation and gonadal function were observed on day 6–8 and day 11–14, respectively. During germ cell migration, quail primordial germ cells (qPGCs) were successfully detected in both left and right genital ridges as well as the dorsal mesentery by lectin histochemistry. Unexpectedly, qPGCs-like cells were found next to the neural tube by Mallory-AZAN stain. During gonadal differentiation, embryonic sex can be distinguished histologically since day 8 of incubation. Embryonic testis exhibited a thin cortex, whereas embryonic ovary exhibited a thick cortex. Testicular cord formation was found in the medulla of embryonic testes while the lacunae and fat-laden cells were found in the medulla of embryonic ovary during gonadal function. This is the first report on a comparison of phases of gonadogenesis and histochemical study of quail embryonic gonads in both sexes.


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