Transformations in the abdominal muscles of the blue blow-fly, Calliphora erythrocephala (Meig), during metamorphosis

Development ◽  
1965 ◽  
Vol 14 (1) ◽  
pp. 89-110
Author(s):  
A. C. S. Crossley
Keyword(s):  
Embryonic Development ◽  
Abdominal Muscles ◽  
Blow Fly ◽  
Cell Nuclei ◽  
Fat Cell ◽  
Calliphora Erythrocephala ◽  
Early Literature ◽  
Insight Into

In the century that has elapsed since Weismann (1864) published his pioneer work on insect post-embryonic development, the changes in insect muscles at metamorphosis have been studied by numerous workers. Although the treatises of Breed (1903) and Perez (1910) provide an insight into earlier work, a brief survey of the early literature is included here to clarify the origin of certain terms that have come into general use, and this survey is extended to include the more recent studies pertaining to muscle metamorphosis in Diptera. Weismann (1864), in his work on Calliphora erythrocephala and Sarcophaga carnaria, described the breakdown of larval tissues in the puparium to form a thick suspension of fatty droplets in the haemolymph. Aggregations of these droplets were said to surround themselves with a membrane, becoming ‘Kornchenkugeln’, from which materialized a mass of nuclei (unrelated to haemocyte or fat cell nuclei), which were said to subsequently differentiate into imaginal structures, including muscles.

scholarly journals Ribosomal Protein S6 Gene Haploinsufficiency Is Associated with Activation of a p53-Dependent Checkpoint during Gastrulation

2006 ◽  
Vol 26 (23) ◽  
pp. 8880-8891 ◽  
Author(s):  
Linda Panić ◽  
Sanda Tamarut ◽  
Melanie Sticker-Jantscheff ◽  
Martina Barkić ◽  
Davor Solter ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Embryonic Development ◽  
Ribosomal Protein ◽  
Ribosome Biogenesis ◽  
Fetal Liver ◽  
Genetic Inactivation ◽  
Developmental Program ◽  
Ribosomal Protein S6 ◽  
M Phase ◽  
Insight Into

ABSTRACT Nascent ribosome biogenesis is required during cell growth. To gain insight into the importance of this process during mouse oogenesis and embryonic development, we deleted one allele of the ribosomal protein S6 gene in growing oocytes and generated S6-heterozygous embryos. Oogenesis and embryonic development until embryonic day 5.5 (E5.5) were normal. However, inhibition of entry into M phase of the cell cycle and apoptosis became evident post-E5.5 and led to perigastrulation lethality. Genetic inactivation of p53 bypassed this checkpoint and prolonged development until E12.5, when the embryos died, showing decreased expression of D-type cyclins, diminished fetal liver erythropoiesis, and placental defects. Thus, a p53-dependent checkpoint is activated during gastrulation in response to ribosome insufficiency to prevent improper execution of the developmental program.

Mechanics of Embryonic Head Fold Morphogenesis

2008 ◽  
Author(s):  
Victor D. Varner ◽  
Dmitry A. Voronov ◽  
Larry A. Taber
Keyword(s):  
Embryonic Development ◽  
Incubation Period ◽  
Neural Plate ◽  
Vitelline Membrane ◽  
Heart Tube ◽  
Germ Layers ◽  
Embryonic Tissues ◽  
Anterior Extent ◽  
Insight Into ◽  
Embryonic Head

Head fold morphogenesis constitutes the first discernible epithelial folding event in the embryonic development of the chick. It arises at Hamburger and Hamilton (HH) stage 6 (approximately 24 hours into a 21-day incubation period) and establishes the anterior extent of the embryo [1]. At this stage, the embryonic blastoderm is composed of three germ layers (endoderm, mesoderm, and ectoderm), which are organized into a flat layered sheet that overlies the fibrous vitelline membrane (VM). Within this blastodermal sheet, a crescent-shaped head fold develops just anterior to the elongating notochord, spanning across the embryonic midline at the rostral end of neural plate. At the crest of this fold, the bilateral precardiac plates fuse in a cranial to caudal direction and give rise to the primitive heart tube and foregut [2, 3]. An understanding of head fold morphogenesis may thus offer insight into how embryonic tissues are arranged to make ready for proper cardiac formation.

scholarly journals Nucleosome–nucleosome interactions via histone tails and linker DNA regulate nuclear rigidity

2017 ◽  
Vol 28 (11) ◽  
pp. 1580-1589 ◽  
Author(s):  
Yuta Shimamoto ◽  
Sachiko Tamura ◽  
Hiroshi Masumoto ◽  
Kazuhiro Maeshima
Keyword(s):  
Molecular Mechanisms ◽  
Mechanical Response ◽  
Nuclear Architecture ◽  
Living Cells ◽  
Genome Integrity ◽  
Biological Processes ◽  
Cell Nuclei ◽  
Histone Tails ◽  
Insight Into

Cells, as well as the nuclei inside them, experience significant mechanical stress in diverse biological processes, including contraction, migration, and adhesion. The structural stability of nuclei must therefore be maintained in order to protect genome integrity. Despite extensive knowledge on nuclear architecture and components, however, the underlying physical and molecular mechanisms remain largely unknown. We address this by subjecting isolated human cell nuclei to microneedle-based quantitative micromanipulation with a series of biochemical perturbations of the chromatin. We find that the mechanical rigidity of nuclei depends on the continuity of the nucleosomal fiber and interactions between nucleosomes. Disrupting these chromatin features by varying cation concentration, acetylating histone tails, or digesting linker DNA results in loss of nuclear rigidity. In contrast, the levels of key chromatin assembly factors, including cohesin, condensin II, and CTCF, and a major nuclear envelope protein, lamin, are unaffected. Together with in situ evidence using living cells and a simple mechanical model, our findings reveal a chromatin-based regulation of the nuclear mechanical response and provide insight into the significance of local and global chromatin structures, such as those associated with interdigitated or melted nucleosomal fibers.

scholarly journals BOTH NUCLEOLAR ORGANIZERS ARE REPLICATED IN DIPTERAN POLYPLOID TISSUES: A STUDY AT THE LEVEL OF INDIVIDUAL NUCLEI

Genetics ◽  
1985 ◽  
Vol 111 (2) ◽  
pp. 325-336
Author(s):  
Esther J Belikoff ◽  
Kathy Beckingham
Keyword(s):  
Salivary Gland ◽  
Nurse Cell ◽  
Nuclear Dna ◽  
Organizer Region ◽  
Nucleolar Organizer Region ◽  
Nucleolar Organizer ◽  
Single Pair ◽  
Cell Nuclei ◽  
Calliphora Erythrocephala ◽  
Nontranscribed Spacer

ABSTRACT Working with the Dipteran Calliphora erythrocephala, we have tested the hypothesis that only one nucleolar organizer region (NO) is replicated during polyploidization. NO replication was examined in two very different highly polyploid nuclear types: salivary gland nuclei and nurse cell nuclei. Two strains of the organism containing NO regions with highly diagnostic nontranscribed spacer (NTS) polymorphisms were prepared and reciprocal single pair-matings between members of the strains were performed. The representation of the two distinguishable NOs in diploid and polyploid DNAs of individual F1 progeny from each cross was then examined. DNA from a total polyploid nuclear DNA preparation and from individual polyploid nuclei of both tissue types was analyzed. Our results show conclusively that both genomic NOs are replicated in individual polyploid nuclei of both types. Further, evidence for variation in the relative replication of cistrons from the two NOs by individual nuclei was obtained. The cistron types present in the NOs of both strains showed differential replication upon polyploidization. In general, the patterns of differential cistron replication seen in salivary gland and nurse cell nuclei were similar.

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