The Cytoskeleton of the Early Drosophila Embryo

Maternally inherited cytoplasmic bacteria have occasionally been observed in embryos and adults of different strains of several Drosophila species. While there is a considerable body of data on the relationship between bacteria and embryo viability, little is known about the behavior of these bacteria during the early development of Drosophila. In eggs laid by infected Drosophila melanogaster females we showed that cytoplasmic bacteria were initially concentrated in a thin cortical layer and scattered in the yolk region. During the following syncytial blastoderm mitoses the bacteria mainly accumulated towards the poles of the mitotic spindles, suggesting that astral microtubules play a role in localizing bacteria. This is supported by the observation that treatment of the infected embryos with the microtubule-disrupting drug colchicine led to the partial dissociation of the bacteria from the spindle poles, whereas cytochalasin treatment left almost all the bacterial clusters intact. Moreover, bacteria were not found near the polar bodies and yolk nuclei, which were without astral microtubules. In mitosis-defective embryos, with centrosomes dissociated from the nuclei, the bacteria were concentrated in association with the isolated astral microtubules, and in cold-treated embryos, in which microtubules regrew from isolated centrosomes after recovering, the bacteria clustered around the newly formed asters. These observations, also supported by electron microscope analysis, indicate a close relationship between cytoplasmic bacteria and astral microtubules, and suggest that the latter were able to build discrete cytoplasmic domains ensuring the proper distribution of cytoplasmic components during the blastoderm mitoses, despite the lack of cell membranes.

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Evolution of maternal and zygotic mRNA complements in the early Drosophila embryo

PLoS Genetics ◽

10.1371/journal.pgen.1007838 ◽

2018 ◽

Vol 14 (12) ◽

pp. e1007838 ◽

Cited By ~ 7

Author(s):

Joel Atallah ◽

Susan E. Lott

Keyword(s):

Drosophila Embryo ◽

Early Drosophila Embryo

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The GAGA factor is required in the early Drosophila embryo not only for transcriptional regulation but also for nuclear division

Development ◽

10.1242/dev.122.4.1113 ◽

1996 ◽

Vol 122 (4) ◽

pp. 1113-1124 ◽

Cited By ~ 1

Author(s):

K.M. Bhat ◽

G. Farkas ◽

F. Karch ◽

H. Gyurkovics ◽

J. Gausz ◽

...

Keyword(s):

Gene Expression ◽

Chromatin Remodeling ◽

In Vitro Transcription ◽

Drosophila Embryo ◽

Gaga Factor ◽

Early Drosophila Embryo ◽

Hypersensitive Sites ◽

And Function ◽

Stimulatory Factor

The GAGA protein of Drosophila was first identified as a stimulatory factor in in vitro transcription assays using the engrailed and Ultrabithorax promoters. Subsequent studies have suggested that the GAGA factor promotes transcription by blocking the repressive effects of histones; moreover, it has been shown to function in chromatin remodeling, acting together with other factors in the formation of nuclease hypersensitive sites in vitro. The GAGA factor is encoded by the Trithorax-like locus and in the studies reported here we have used the maternal effect allele Trl13C to examine the functions of the protein during embryogenesis. We find that GAGA is required for the proper expression of a variety of developmental loci that contain GAGA binding sites in their upstream regulatory regions. The observed disruptions in gene expression are consistent with those expected for a factor involved in chromatin remodeling. In addition to facilitating gene expression, the GAGA factor appears to have a more global role in chromosome structure and function. This is suggested by the spectrum of nuclear cleavage cycle defects observed in Trl13C embryos. These defects include asynchrony in the cleavage cycles, failure in chromosome condensation, abnormal chromosome segregation and chromosome fragmentation. These defects are likely to be related to the association of the GAGA protein with heterochromatic satellite sequences which is observed throughout the cell cycle.

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Correction: P-TEFb, the Super Elongation Complex and Mediator Regulate a Subset of Non-paused Genes during Early Drosophila Embryo Development

PLoS Genetics ◽

10.1371/journal.pgen.1005319 ◽

2015 ◽

Vol 11 (6) ◽

pp. e1005319

Author(s):

Keyword(s):

Embryo Development ◽

Drosophila Embryo ◽

Elongation Complex ◽

Super Elongation Complex ◽

Early Drosophila Embryo

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The somatic-visceral subdivision of the embryonic mesoderm is initiated by dorsal gradient thresholds in Drosophila

Development ◽

10.1242/dev.121.7.2107 ◽

1995 ◽

Vol 121 (7) ◽

pp. 2107-2116 ◽

Cited By ~ 5

Author(s):

K. Maggert ◽

M. Levine ◽

M. Frasch

Keyword(s):

Expression Pattern ◽

Target Genes ◽

Substantial Reduction ◽

Drosophila Embryo ◽

Germ Layers ◽

Cardiac Tissues ◽

Early Drosophila Embryo ◽

Dorsal Ectoderm ◽

Lateral Mesoderm

The maternal dorsal regulatory gradient initiates the differentiation of the mesoderm, neuroectoderm and dorsal ectoderm in the early Drosophila embryo. Two primary dorsal target genes, snail (sna) and decapentaplegic (dpp), define the limits of the presumptive mesoderm and dorsal ectoderm, respectively. Normally, the sna expression pattern encompasses 18–20 cells in ventral and ventrolateral regions. Here we show that narrowing the sna pattern results in fewer invaginated cells. As a result, the mesoderm fails to extend into lateral regions so that fewer cells come into contact with dpp-expressing regions of the dorsal ectoderm. This leads to a substantial reduction in visceral and cardiac tissues, consistent with recent studies suggesting that dpp induces lateral mesoderm. These results also suggest that the dorsal regulatory gradient defines the limits of inductive interactions between germ layers after gastrulation. We discuss the parallels between the subdivision of the mesoderm and dorsal ectoderm.

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