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Schematic drawing of the early stages of oogenesis in the Drosophila germarium depicting the localization of the elongated centriole (GSC, germline stem cell; Cy, cystoblast).
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Among the morphological processes that characterize the early stages of Drosophila oogenesis, the dynamic of the centrioles deserves particular attention. We re-examined the architecture and the distribution of the centrioles within the germarium and early stages of the vitellarium. We found that most of the germ cell centrioles diverge from the ca...
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Context 1
... and random sections of several 16-cell cysts showed that this elongated centriole was present in only one cell from each cyst. Remarkably, this unique centriole was always associated in region 2a with one of the two pro-oocytes, and it was found in region 2b in the cytoplasm of the posterior cell that retains the synaptonemal complex and accumulates multiple centrioles ( Figure 6). These observations led us to infer that this unique centriole present in the cystoblast is directly inherited by the oocyte, thus representing a clear asymmetry which is established just after the division of the stem cell. ...
Citations
... The epigenetic plasticity of Drosophila somatic cells and the conversion of somatic cells into germline cells show the existence of parts of the RP/GSC cycle in Drosophila gametogenesis. 49,72,73 The Defective SCD Germline; Loss of Function due to Homologous Recombination Deficiency ...
Oncogenesis and the origin of cancer are still not fully understood despite the efforts of his-tologists, pathologists, and molecular geneticists to determine how cancer develops. Previousembryogenic and gene- and genome-based hypotheses have attempted to solve this enigma.Each of them has its kernel of truth, but a unifying, universally accepted theory is still missing.Fortunately, a unicellular cell system has been found in amoebozoans, which exhibits all thebasic characteristics of the cancer life cycle and demonstrates that cancer is not a biologicalaberration but a consequence of molecular and cellular evolution. The impressive systemicsimilarities between the life cycle of Entamoeba and the life cycle of cancer demonstrate thedeep homology of cancer to the amoebozoans, metazoans, and fungi ancestor that branched intothe clades of Amoebozoa, Metazoa, and Fungi (AMF) and shows that the roots of oncogenesisand tumorigenesis lie in an ancient gene network, which is conserved in the genome of allmetazoans and humans. This evolutionary gene network theory of cancer (evolutionary cancergenome theory) integrates previous findings and hypotheses and is one step further along theroad to a universal cancer cell theory. It supports genetic cancer medicine and recommendssoma-to-germ transitions—referred to as epithelial-to-mesenchymal transition in cancer—andcancer germline as potential targets. According to the evolutionary cancer genome theory, cancerexploits an ancient gene network module of premetazoan origin
(16) (PDF) The evolutionary cancer genome theory and its reasoning. Available from: https://www.researchgate.net/publication/370218917_The_evolutionary_cancer_genome_theory_and_its_reasoning?origin=mail&uploadChannel=re390&reqAcc=Matheus-Casotti&useStoredCopy=0 [accessed Mar 05 2024].
... In particular, the two older sister cells that originate by the first division of the cystoblast, the pro-oocytes, have four ring canals. The pro-oocyte that inherits from the cystoblast an unusually long mother centriole [3] and the main part of the spectrosome [4] will be the differentiating oocyte, whereas the sister cell will turn into the 15-nurse cell cluster that provides the cytoplasmic components need for oocyte growth and maturation. ...
... We observed, indeed, longitudinal microtubules that cross the membrane projections or end to the AJs at the interface between the follicle cells and the oocyte. An additional aspect characterizing the early Drosophila oogenesis is the presence of centriole pairs in which one procentriole was often found orthogonal to its mother [3]. This condition that was observed within the germarium and during early stages in the vitellarium suggests that post-mitotic centrioles can duplicate independently of the DNA replication that ceases after the fourth mitotic division of the germ cells. ...
Drosophila oogenesis requires the subsequent growth of distinct egg chambers each containing a group of sixteen germline cells surrounded by a simple epithelium of follicle cells. The oocyte occupies a posterior position within the germ cells, thus giving a distinct asymmetry to the egg chamber. Although this disposition is critical for the formation of the anterior–posterior axis of the embryo, the interplay between somatic and germ cells during the early stages of oogenesis remains an open question. We uncover by stage 2, when the egg chambers leaved the germarium, some unique spatial interactions between the posterior follicle cells and the oocyte. These interactions are restricted to the surface of the oocyte over the centriole cluster that formed during early oogenesis. Moreover, the posterior follicle cells in front of the oocyte display a convoluted apical membrane with extensive contacts, whereas the other follicle cells have a flat apical surface without obvious surface protrusions. In addition, the germ cells located at the posterior end of the egg chamber have very elongated protrusions that come into contact with each other or with facing follicle cells. These observations point to distinct polarization events during early oogenesis supporting previous molecular data of an inherent asymmetry between the anterior and the posterior regions of the egg chambers.
