Comparative survey of early embryogenesis of Secernentea (Nematoda), with phylogenetic implications

2001 ◽  
Vol 79 (1) ◽  
pp. 82-94 ◽  
Author(s):  
C Dolinski ◽  
J G Baldwin ◽  
W K Thomas
Keyword(s):  
Caenorhabditis Elegans ◽  
Germ Cell ◽  
Early Development ◽  
Early Embryo ◽  
Early Embryogenesis ◽  
Asynchronous Development ◽  
Phylogenetic Implications ◽  
Comparative Survey ◽  
Molecular Phylogenies ◽  
Insight Into

Insight into the evolution of class Secernentea (Nematoda) for the purpose of providing a phylogenetic context for the model Caenorhabditis elegans is being gained from the use of molecular character sets. Such phylogenies provide a framework for mapping the evolution of diversity in some early-development characters for 70 species and 19 families of Secernentea. These characters include (i) whether AB and P1 blastomeres initially develop at the same (synchronous) or different (asynchronous) rates, (ii) whether AB and P1 are initially aligned along the linear axis of the embryo (tandem pattern) or obliquely (rhomboidal pattern), and (iii) whether the founder germ cell, P4, is established early, i.e., by the sixth cleavage, or later. Evolutionary polarity of characters was evaluated through outgroup comparisons. From our data the following inferences are made. The derived character, late establishment of P4, evolved primarily in the ancestor of the monophyletic groups Diplogastrina, Rhabditina, and Panagrolaimidae. Asynchronous development is convergent, defining one clade of Tylenchina as well as Cephalobina, and also arising independently in Aphelenchina. The rhomboidal embryo is ancestral to the tandem-pattern embryo that defines a second clade of Tylenchina. Early-embryo characters are congruent with the polyphyly of Cephalobina and Aphelenchina, as has been demonstrated by molecular phylogenies. Many aspects of early embryogenesis, rather than being highly conserved, evolve at a rate appropriate to defining taxa within Secernentea.

Drosophila virilis oskar transgenes direct body patterning but not pole cell formation or maintenance of mRNA localization in D. melanogaster

Development ◽  
1994 ◽  
Vol 120 (7) ◽  
pp. 2027-2037 ◽  
Author(s):  
P.J. Webster ◽  
J. Suen ◽  
P.M. Macdonald
Keyword(s):  
Drosophila Melanogaster ◽  
Germ Cell ◽  
Cell Formation ◽  
Mrna Localization ◽  
Early Embryo ◽  
Posterior Pole ◽  
Early Embryogenesis ◽  
Drosophila Virilis ◽  
Pole Cell ◽  
Body Patterning

The Drosophila melanogaster gene oskar is required for both posterior body patterning and germline formation in the early embryo; precisely how oskar functions is unknown. The oskar transcript is localized to the posterior pole of the developing oocyte, and oskar mRNA and protein are maintained at the pole through early embryogenesis. The posterior maintenance of oskar mRNA is dependent upon the presence of oskar protein. We have cloned and characterized the Drosophila virilis oskar homologue, virosk, and examined its activity as a transgene in Drosophila melanogaster flies. We find that the cis-acting mRNA localization signals are conserved, although the virosk transcript also transiently accumulates at novel intermediate sites. The virosk protein, however, shows substantial differences from oskar: while virosk is able to rescue body patterning in a D. melanogaster oskar- background, it is impaired in both mRNA maintenance and pole cell formation. Furthermore, virosk induces a dominant maternal-effect lethality when introduced into a wild-type background, and interferes with the posterior maintenance of the endogenous oskar transcript in early embryogenesis. Our data suggest that virosk protein is unable to anchor at the posterior pole of the early embryo; this defect could account for all of the characteristics of virosk mentioned above. Our observations support a model in which oskar protein functions both by nucleating the factors necessary for the activation of the posterior body patterning determinant and the germ cell determinant, and by anchoring these factors to the posterior pole of the embryo. While the posterior body patterning determinant need not be correctly localized to provide body patterning activity, the germ cell determinant may need to be highly concentrated adjacent to the cortex in order to direct pole cell formation.

Insect embryogenesis – what is ancestral and what is derived?

Development ◽  
1994 ◽  
Vol 1994 (Supplement) ◽  
pp. 193-199
Author(s):  
Diethard Tautz ◽  
Markus Friedrich ◽  
Reinhard Schröder
Keyword(s):  
Pattern Formation ◽  
Genetic Analysis ◽  
Early Development ◽  
Molecular Mechanisms ◽  
Early Embryogenesis ◽  
Molecular Pathways ◽  
Deep Insight ◽  
Insect Embryogenesis ◽  
Definitive Answer ◽  
Insight Into

The systematic genetic analysis of Drosophila development has provided us with a deep insight into the molecular pathways of early embryogenesis. The question arises now whether these insights can serve as a more general paradigm of early development, or whether they apply only to advanced insect orders. Though it is too early to give a definitive answer to this question, we suggest that there is currently no firm reason to believe that the molecular mechanisms that were elucidated in Drosophila may not also apply to other forms of insect embryogenesis. Thus, many of the Drosophila genes involved in early pattern formation may have comparable functions in other insects and possibly throughout the arthropods.

scholarly journals CFTR is required for the migration of primordial germ cells during zebrafish early embryogenesis

Reproduction ◽  
2018 ◽  
Vol 156 (3) ◽  
pp. 261-268 ◽  
Author(s):  
Huijuan Liao ◽  
Yan Chen ◽  
Yulong Li ◽  
Shaolong Xue ◽  
Mingfeng Liu ◽  
...  
Keyword(s):  
Germ Cell ◽  
Germ Cells ◽  
Primordial Germ Cells ◽  
Cell Development ◽  
Early Embryo ◽  
Early Embryogenesis ◽  
Key Factors ◽  
Zebrafish Model ◽  
Germ Cell Development

Mutations in the cystic fibrosis transmembrane conductance regulator (CFTR) gene affect fertility in both sexes. However, the involvement of CFTR in regulating germ cell development remains largely unknown. Here, we used zebrafish model to investigate the role of CFTR in primordial germ cells (PGCs) development. We generated a cftr frameshift mutant zebrafish line using CRISPR/Cas9 technique and investigated the migration of PGCs during early embryo development. Our results showed that loss of Cftr impairs the migration of PGCs from dome stages onward. The migration of PGCs was also perturbed by treatment of CFTRinh-172, a gating-specific CFTR channel inhibitor. Moreover, defected PGCs migration in cftr mutant embryos can be partially rescued by injection of WT but not other channel-defective mutant cftr mRNAs. Finally, we observed the elevation of cxcr4b, cxcl12a, rgs14a and ca15b, key factors involved in zebrafish PGCs migration, in cftr-mutant zebrafish embryos. Taken together, the present study revealed an important role of CFTR acting as an ion channel in regulating PGCs migration during early embryogenesis. Defect of which may impair germ cell development through elevation of key factors involved in cell motility and response to chemotactic gradient in PGCs.

In Caenorhabditis elegans, the RNA-Binding Domains of the Cytoplasmic Polyadenylation Element Binding Protein FOG-1 Are Needed to Regulate Germ Cell Fates

Genetics ◽  
2001 ◽  
Vol 159 (4) ◽  
pp. 1617-1630
Author(s):  
Suk-Won Jin ◽  
Nancy Arno ◽  
Adam Cohen ◽  
Amy Shah ◽  
Qijin Xu ◽  
...  
Keyword(s):  
Caenorhabditis Elegans ◽  
Germ Cell ◽  
Rna Binding ◽  
Dominant Negative ◽  
Missense Mutations ◽  
Biochemical Tests ◽  
Cell Fates ◽  
Cytoplasmic Polyadenylation ◽  
Binding Domains ◽  
Rna Binding Domains

Abstract FOG-1 controls germ cell fates in the nematode Caenorhabditis elegans. Sequence analyses revealed that FOG-1 is a cytoplasmic polyadenylation element binding (CPEB) protein; similar proteins from other species have been shown to bind messenger RNAs and regulate their translation. Our analyses of fog-1 mutations indicate that each of the three RNA-binding domains of FOG-1 is essential for activity. In addition, biochemical tests show that FOG-1 is capable of binding RNA sequences in the 3′-untranslated region of its own message. Finally, genetic assays reveal that fog-1 functions zygotically, that the small fog-1 transcript has no detectable function, and that missense mutations in fog-1 cause a dominant negative phenotype. This last observation suggests that FOG-1 acts in a complex, or as a multimer, to regulate translation. On the basis of these data, we propose that FOG-1 binds RNA to regulate germ cell fates and that it does so by controlling the translation of its targets. One of these targets might be the fog-1 transcript itself.

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