Co-localization of DrPiwi-1 and DrPiwi-2 in the oogonial cytoplasm is essential for oocyte differentiation in sexualized planarians

SummaryThe ultrastructural changes accompanying oocyte differentiation in the ovaries of the monogeneans, Diclidophora merlangi, Diplozoon paradoxum and Calicotyle kröyeri have been described. In each case, oogenesis in the ovary proceeds as far as meiotic prophase in the primary oocyte. A three-stage sequence of development based on oocyte morphology is proposed: (1) Oogonia and early, immature primary oocytes are typically undifferentiated, with chromatin-laden nuclei occupying most of the cell volume. The cytoplasm contains small clumps of mitochrondria and unattached ribosomal aggregates. There is evidence of mitosis and, in later stages, meiotic prophase is indicated by the appearance of nuclear synaptonemal complexes. (2) Maturing primary oocytes are characterized by increased nucleolar volume associated with the production of RNA for export to the cytoplasm. An organized GER and Golgi apparatus are established and involved in the synthesis and packaging of membrane-limited cortical granules. Annulate lamellae and nucleolus-like bodies appear in the cytoplasm and, with development, the cells increase in size and, peripherally, become interdigitated. (3) Mature primary oocytes represent a resting phase when cellular activity is minimal. Golgi disappear and the ER fragments or becomes reduced in dimensions. Mitochondria and free ribo-somes are numerous and cortical granules move to the cell periphery. The cells separate and, when mature, are released from the ovary. There are minor species differences in oocyte ultrastructure and development.

Download Full-text

Localization of DNA methyltransferase-1 during oocyte differentiation, in vitro maturation and early embryonic development in cow

European Journal of Histochemistry ◽

10.4081/ejh.2009.e24 ◽

2009 ◽

Vol 53 (4) ◽

pp. 24 ◽

Cited By ~ 24

Author(s):

V. Lodde ◽

S. C. Modina ◽

F. Franciosi ◽

E. Zuccari ◽

I. Tessaro ◽

...

Keyword(s):

Embryonic Development ◽

Dna Methyltransferase ◽

In Vitro Maturation ◽

Early Embryonic Development ◽

Dna Methyltransferase 1 ◽

Oocyte Differentiation ◽

Methyltransferase 1

Download Full-text

The Trithorax group protein dMLL3/4 instructs the assembly of the zygotic genome at fertilization

10.1101/242008 ◽

2018 ◽

Author(s):

Pedro Prudêncio ◽

Leonardo G. Guilgur ◽

João Sobral ◽

Jörg D. Becker ◽

Rui Gonçalo Martinho ◽

...

Keyword(s):

Transcriptional Control ◽

Transcriptional Program ◽

Gene Subset ◽

Paternal Genome ◽

Trithorax Group ◽

Evolutionarily Conserved ◽

Group Protein ◽

Oocyte Differentiation ◽

Zygotic Genome

ABSTRACTThe transition from fertilized oocyte to totipotent embryo relies on maternally-provided factors that are synthetized and accumulated in developing oocytes. Yet, it is still unclear how oocytes regulate the expression of these embryo fate-promoting genes within the general transcriptional program of oogenesis. Here we report that the Drosophila Trithorax group protein MLL3/4 (dMLL3/4, also known as Trr) is essential for the transition to embryo fate at fertilization. In the absence of dMLL3/4, oocytes develop normally but fail to initiate the embryo mitotic divisions after fertilization. This incapability results from defects in both paternal genome reprogramming and maternal meiotic completion. We show that, during oogenesis, dMLL3/4 promotes the expression of a functionally coherent gene subset that is later required for the correct assembly of the zygotic genome. Accordingly, we identify the evolutionarily-conserved IDGF4 glycoprotein (known as oviductin in mammals) as a new oocyte-to-embryo transition gene under dMLL3/4 transcriptional control. Based on these observations, we propose that dMLL3/4 plays an instructive role in the oocyte-to-embryo transition that is functionally uncoupled from the requirements of normal oocyte differentiation.

Download Full-text

OOCYTE DIFFERENTIATION IN THE SEA URCHIN, ARBACIA PUNCTULATA, WITH PARTICULAR REFERENCE TO THE ORIGIN OF CORTICAL GRANULES AND THEIR PARTICIPATION IN THE CORTICAL REACTION

The Journal of Cell Biology ◽

10.1083/jcb.37.2.514 ◽

1968 ◽

Vol 37 (2) ◽

pp. 514-539 ◽

Cited By ~ 198

Author(s):

Everett Anderson

Keyword(s):

Sea Urchin ◽

Golgi Complex ◽

Morphological Evidence ◽

Cortical Granule ◽

Perivitelline Space ◽

Unit Membrane ◽

Cortical Granules ◽

Arbacia Punctulata ◽

Cortical Reaction ◽

Oocyte Differentiation

This paper presents morphological evidence on the origin of cortical granules in the oocytes of Arbacia punctulata and other echinoderms. During oocyte differentiation, those Golgi complexes associated with the production of cortical granules are composed of numerous saccules with companion vesicles. Each element of the Golgi complex contains a rather dense homogeneous substance. The vesicular component of the Golgi complex is thought to be derived from the saccular member by a pinching-off process. The pinched-off vesicles are viewed as containers of the precursor(s) of the cortical granules. In time, they coalesce and form a mature cortical granule whose content is bounded by a unit membrane. Thus, it is asserted that the Golgi complex is involved in both the synthesis and concentration of precursors utilized in the construction of the cortical granule. Immediately after the egg is activated by the sperm the primary envelope becomes detached from the oolemma, thereby forming what we have called the activation calyx (see Discussion). Subsequent to the elaboration of the activation calyx, the contents of cortical granules are released (cortical reaction) into the perivitelline space. The discharge of the constituents of a cortical granule is accomplished by the union of its encompassing unit membrane, in several places, with the oolemma.

Download Full-text

The microtubule motor cytoplasmic dynein is required for spindle orientation during germline cell divisions and oocyte differentiation in Drosophila

Development ◽

10.1242/dev.124.12.2409 ◽

1997 ◽

Vol 124 (12) ◽

pp. 2409-2419 ◽

Cited By ~ 15

Author(s):

M. McGrail ◽

T.S. Hays

Keyword(s):

Asymmetric Cell Division ◽

Fruit Fly ◽

Cytoplasmic Dynein ◽

Spindle Orientation ◽

Chain Gene ◽

Animal Development ◽

Dynein Motor ◽

Microtubule Motor ◽

Two Stages ◽

Oocyte Differentiation

During animal development cellular differentiation is often preceded by an asymmetric cell division whose polarity is determined by the orientation of the mitotic spindle. In the fruit fly, Drosophila melanogaster, the oocyte differentiates in a 16-cell syncytium that arises from a cystoblast which undergoes 4 synchronous divisions with incomplete cytokinesis. During these divisions, spindle orientation is highly ordered and is thought to impart a polarity to the cyst that is necessary for the subsequent differentiation of the oocyte. Using mutations in the Drosophila cytoplasmic dynein heavy chain gene, Dhc64C, we show that cytoplasmic dynein is required at two stages of oogenesis. Early in oogenesis, dynein mutations disrupt spindle orientation in dividing cysts and block oocyte determination. The localization of dynein in mitotic cysts suggests spindle orientation is mediated by the microtubule motor cytoplasmic dynein. Later in oogenesis, dynein function is necessary for proper differentiation, but does not appear to participate in morphogen localization within the oocyte. These results provide evidence for a novel developmental role for the cytoplasmic dynein motor in cellular determination and differentiation.

Download Full-text

Lis1, the Drosophila homolog of a human lissencephaly disease gene, is required for germline cell division and oocyte differentiation

Development ◽

10.1242/dev.126.20.4477 ◽

1999 ◽

Vol 126 (20) ◽

pp. 4477-4488 ◽

Cited By ~ 2

Author(s):

Z. Liu ◽

T. Xie ◽

R. Steward

Keyword(s):

Cell Division ◽

Neuronal Migration ◽

Nuclear Migration ◽

Germline Cell ◽

Causal Gene ◽

Membrane Cytoskeleton ◽

Drosophila Homolog ◽

Congenital Brain Malformation ◽

Development Analysis ◽

Oocyte Differentiation

Lissencephaly is a severe congenital brain malformation resulting from incomplete neuronal migration. One causal gene, LIS1, is homologous to nudF, a gene required for nuclear migration in A. nidulans. We have characterized the Drosophila homolog of LIS1 (Lis1) and show that Lis1 is essential for fly development. Analysis of ovarian Lis1 mutant clones demonstrates that Lis1 is required in the germline for synchronized germline cell division, fusome integrity and oocyte differentiation. Abnormal packaging of the cysts was observed in Lis1 mutant clones. Our results indicate that LIS1 is important for cell division and differentiation and the function of the membrane cytoskeleton. They support the notion that LIS1 functions with the dynein complex to regulate nuclear migration or cell migration.

Download Full-text

The fusome organizes the microtubule network during oocyte differentiation in Drosophila

Development ◽

10.1242/dev.127.19.4253 ◽

2000 ◽

Vol 127 (19) ◽

pp. 4253-4264 ◽

Cited By ~ 14

Author(s):

N.C. Grieder ◽

M. de Cuevas ◽

A.C. Spradling

Keyword(s):

Germ Cell ◽

Germ Cells ◽

Meiotic Prophase ◽

Crucial Role ◽

Skeletal Structure ◽

Network Organization ◽

Microtubule Network ◽

Complex Process ◽

Gamma Tubulin ◽

Oocyte Differentiation

Differentiation of the Drosophila oocyte takes place in a cyst of 16 interconnected germ cells and is dependent on a network of microtubules that becomes polarized as differentiation progresses (polarization). We have investigated how the microtubule network polarizes using a GFP-tubulin construct that allows germ-cell microtubules to be visualized with greater sensitivity than in previous studies. Unexpectedly, microtubules are seen to associate with the fusome, an asymmetric germline-specific organelle, which elaborates as cysts form and undergoes complex changes during cyst polarization. This fusome-microtubule association occurs periodically during late interphases of cyst divisions and then continuously in 16-cell cysts that have entered meiotic prophase. As meiotic cysts move through the germarium, microtubule minus ends progressively focus towards the center of the fusome, as visualized using a NOD-lacZ marker. During this same period, discrete foci rich in gamma tubulin that very probably correspond to migrating cystocyte centrosomes also associate with the fusome, first on the fusome arms and then in its center, subsequently moving into the differentiating oocyte. The fusome is required for this complex process, because microtubule network organization and polarization are disrupted in hts(1) mutant cysts, which lack fusomes. Our results suggest that the fusome, a specialized membrane-skeletal structure, which arises in early germ cells, plays a crucial role in polarizing 16-cell cysts, at least in part by interacting with microtubules and centrosomes.

Download Full-text