scholarly journals Asters push embryonic nuclei to the brink

2012 ◽  
Vol 197 (7) ◽  
pp. 853-853
Author(s):  
Mitch Leslie
Keyword(s):  
Insect Embryos

Researchers discover how nuclei in insect embryos travel to the cortex.

The dissociation of insect embryos for cell culture

In Vitro ◽  
1976 ◽  
Vol 12 (2) ◽  
pp. 141-146 ◽  
Author(s):  
T. J. Kurtti ◽  
Marion A. Brooks
Keyword(s):  
Cell Culture ◽  
Insect Embryos

Structure of the insect head as revealed by the EN protein pattern in developing embryos

Development ◽  
1996 ◽  
Vol 122 (11) ◽  
pp. 3419-3432 ◽  
Author(s):  
B.T. Rogers ◽  
T.C. Kaufman
Keyword(s):  
Drosophila Melanogaster ◽  
Pattern Formation ◽  
Protein Pattern ◽  
Related Protein ◽  
Specific Expression ◽  
Tissue Specific Expression ◽  
Single Segment ◽  
Dorsal Ridge ◽  
Insect Embryos ◽  
Comparative Embryology

The structure of the insect head has long been a topic of enjoyable yet endless debate among entomologists. More recently geneticists and molecular biologists trying to better understand the structure of the head of the Dipteran Drosophila melanogaster have joined the discourse extrapolating from what they have learned about Drosophila to insects in general. Here we present the results of an investigation into the structure of the insect head as revealed by the distribution of engrailed related protein (Engrailed) in the insect orders Diptera, Siphonaptera, Orthoptera and Hemiptera. The results of this comparative embryology in conjunction with genetic experiments on Drosophila melanogaster lead us to conclude: (1) The insect head is composed of six Engrailed accumulating segments, four postoral and two preoral. The potential seventh and eighth segments (clypeus or labrum) do not accumulate Engrailed. (2) The structure known as the dorsal ridge is not specific to the Diptera but is homologous to structures found in other insect orders. (3) A part of this structure is a single segment-like entity composed of labial and maxillary segment derivatives which produce the most anterior cuticle capable of taking a dorsal fate. The segments anterior to the maxillary segment produce only ventral structures. (4) As in Drosophila, the process of segmentation of the insect head is fundamentally different from the process of segmentation in the trunk. (5) The pattern of Engrailed accumulation and its presumed role in the specification and development of head segments appears to be highly conserved while its role in other pattern formation events and tissue-specific expression is variable. An overview of the pattern of Engrailed accumulation in developing insect embryos provides a basis for discussion of the generality of the parasegment and the evolution of Engrailed patterns.

scholarly journals Timing of increased temperature sensitivity coincides with nervous system development in winter moth embryos

2021 ◽  
Author(s):  
Natalie E. van Dis ◽  
Maurijn van der Zee ◽  
Roelof A. Hut ◽  
Bregje Wertheim ◽  
Marcel E. Visser
Keyword(s):  
Climate Change ◽  
Temperature Sensitivity ◽  
Development Rate ◽  
Egg Development ◽  
Egg Hatching ◽  
Seasonal Timing ◽  
Winter Moth ◽  
Developmental Progression ◽  
Phylotypic Stage ◽  
Insect Embryos

Climate change is rapidly altering the environment and many species will need to genetically adapt their seasonal timing to keep up with these changes. Insect development rate is largely influenced by temperature, but we know little about the mechanisms underlying temperature sensitivity of development. Here we investigate seasonal timing of egg hatching in the winter moth, one of the few species which has been found to genetically adapt to climate change, likely through selection on temperature sensitivity of egg development rate. To study when during development winter moth embryos are most sensitive to changes in ambient temperature, we gave eggs an increase or decrease in temperature at different moments during their development. We measured their developmental progression and timing of egg hatching, and used fluorescence microscopy to construct a timeline of embryonic development for the winter moth. We found that egg development rate responded more strongly to temperature once embryos were in the fully extended germband stage. This is the phylotypic stage at which all insect embryos have developed a rudimentary nervous system. Furthermore, at this stage timing of ecdysone signaling determines developmental progression, which could act as an environment dependent gateway. Intriguingly, this may suggest that, from the phylotypic stage onward, insect embryos can start to integrate internal and environmental stimuli to actively regulate important developmental processes. As we found evidence that there is genetic variation for temperature sensitivity of egg development rate in our study population, such regulation could be a target of selection imposed by climate change.

Stages in the assembly of pleated and smooth septate junctions in developing insect embryos

1982 ◽  
Vol 56 (1) ◽  
pp. 245-262 ◽  
Author(s):  
N.J. Lane ◽  
L.S. Swales
Keyword(s):  
Embryonic Development ◽  
Freeze Fracture ◽  
Organizational Capacity ◽  
Intramembranous Particle ◽  
Septate Junctions ◽  
Thin Sections ◽  
Intramembranous Particles ◽  
Initial Event ◽  
Random Arrays ◽  
Insect Embryos

The stages that occur during the assembly of both pleated and smooth septate junctions in developing insect tissues have been examined. The oesophagus and mid-gut of the embryonic moth, and the oesophagus and central nervous system (CNS) of the locust embryo, have been investigated in thin sections and by freeze-fracture during the course of membrane biogenesis. The smooth septate junctions developing between the lateral borders of the mid-gut exhibit, in the early stages, individual intramembranous particles becoming aligned into short ridges. These ultimately migrate over the membrane face and fuse into longer arrays, which become stacked in parallel with other ridges to form the characteristic mature form of the junction just before hatching. Pleated septate junctions occur between the cells both of the oesophagus and of the perineurium, which ensheathes the neurones and the neuroglial cells in the locust CNS; these are also fully formed by the end of embryonic development. The pleated junctions appear to be assembled during the later stages of CNS or gut differentiation, arising first in embryos about two-thirds of the way through development. During their maturation, the initial event seems to be a membrane depression in the P face, which occurs in patches over the presumptive junctional membrane. Into these depressed regions or ‘formation-plaque’ areas, 8–10 nm particles appear to be inserted intramembranously in apparently random arrays. These particles are the most common elements but larger particles are also present; the former ultimately become aligned in a row. With time, other intramembranous particles come to lie in rows parallel to the original one. By hatching, the typical undulating stacks of parallel intramembranous particle rows are fully formed. Gap junctions also form between the same perineurial or oesophageal cells, usually before, but in some cases at the same time, or just after, the septate junctions have been assembled. Tricellular associations between cells also appear around the same time in embryonic development. The simultaneous assembly of these different junctions reflects a high degree of organizational capacity at the membrane level.

scholarly journals Serosa membrane plays a key role in transferring vitellin polypeptides to the perivitelline fluid in insect embryos

2001 ◽  
Vol 43 (6) ◽  
pp. 725-733 ◽  
Author(s):  
Anna Maria Fausto ◽  
Gabriella Gambellini ◽  
Massimo Mazzini ◽  
Antonella Cecchettini ◽  
Maria Teresa Locci ◽  
...  
Keyword(s):  
Perivitelline Fluid ◽  
Insect Embryos

scholarly journals Aster migration determines the length scale of nuclear separation in the Drosophila syncytial embryo

2012 ◽  
Vol 197 (7) ◽  
pp. 887-895 ◽  
Author(s):  
Ivo A. Telley ◽  
Imre Gáspár ◽  
Anne Ephrussi ◽  
Thomas Surrey
Keyword(s):  
Early Embryo ◽  
Length Scale ◽  
Free System ◽  
Nuclear Separation ◽  
A Cell ◽  
Distinct Distance ◽  
Spindle Elongation ◽  
Insect Embryos ◽  
Microtubule Aster

In the early embryo of many species, comparatively small spindles are positioned near the cell center for subsequent cytokinesis. In most insects, however, rapid nuclear divisions occur in the absence of cytokinesis, and nuclei distribute rapidly throughout the large syncytial embryo. Even distribution and anchoring of nuclei at the embryo cortex are crucial for cellularization of the blastoderm embryo. The principles underlying nuclear dispersal in a syncytium are unclear. We established a cell-free system from individual Drosophila melanogaster embryos that supports successive nuclear division cycles with native characteristics. This allowed us to investigate nuclear separation in predefined volumes. Encapsulating nuclei in microchambers revealed that the early cytoplasm is programmed to separate nuclei a distinct distance. Laser microsurgery revealed an important role of microtubule aster migration through cytoplasmic space, which depended on F-actin and cooperated with anaphase spindle elongation. These activities define a characteristic separation length scale that appears to be a conserved property of developing insect embryos.

Vitellin cleavage products are proteolytically degraded by ubiquitination in stick insect embryos

Micron ◽  
2003 ◽  
Vol 34 (1) ◽  
pp. 39-48 ◽  
Author(s):  
Antonella Cecchettini ◽  
Maria Teresa Locci ◽  
Massimo Masetti ◽  
Anna Maria Fausto ◽  
Gabriella Gambellini ◽  
...  
Keyword(s):  
Stick Insect ◽  
Insect Embryos

Evolutionary change in neural development within the arthropods: axonogenesis in the embryos of two crustaceans

Development ◽  
1993 ◽  
Vol 118 (2) ◽  
pp. 449-461 ◽  
Author(s):  
P.M. Whitington ◽  
D. Leach ◽  
R. Sandeman
Keyword(s):  
Neural Development ◽  
Similar Pattern ◽  
Axon Growth ◽  
Spatiotemporal Pattern ◽  
Freshwater Crayfish ◽  
Relative Order ◽  
Porcellio Scaber ◽  
Central Neurons ◽  
Cherax Destructor ◽  
Insect Embryos

It has been previously suggested that there is a conservative program for neural development amongst the arthropods, on the basis that a stereotyped set of cells involved in establishing the axon tracts in the CNS of insect embryos is also present in crayfish embryos. We have examined the spatiotemporal pattern of axon growth from a set of early differentiating central neurons in the embryo of two crustaceans, the woodlouse Porcellio scaber and the freshwater crayfish Cherax destructor, and drawn comparisons with insect neurons whose somata lie in corresponding positions within the CNS. While many of the woodlouse and crayfish neurons show a similar pattern of axon growth to their insect counterparts, the axon trajectories taken by others differ from those seen in insects. We conclude that this aspect of early neural development has not been rigidly conserved during the evolution of the crustaceans and insects. However, the extent of similarity between the insects and the crustaceans is consistent with the idea that these groups of arthropods share a common evolutionary ‘Bauplan’ for the construction of their nervous systems. While the pattern of early axon growth in the woodlouse and crayfish embryos is sufficiently similar that many neurons could be confidently recognised as homologues, several differences were noted in both the relative order of axon outgrowth and axon morphologies of individual neurons.

Sign in / Sign up

Export Citation Format

Share Document