Simulation of laser-induced ionization in wide bandgap solid dielectrics with a particle-in-cell code.

Modeling the laser-plasma interaction within solids is crucial in controlling ultrafast laser processing of dielectrics, where the pulse propagation and plasma formation dynamics are highly intricate. This is especially important when dealing with nano-scale plasmas where specific phenomena of plasma physics, such as resonance absorption, can significantly impact the energy deposition process. In this article, we report on adapting of a Particle-In-Cell code, EPOCH, to model the laser-plasma interaction within solids.

Fate of neuroblast progeny during postembryonic development of mushroom bodies in the house cricket, Acheta domesticus.

Mushroom bodies represent the main sensory integrative center of the insect brain and probably play a major role in the adaptation of behavioral responses to the environment. Taking into account the continuous neurogenesis of cricket mushroom bodies, we investigated ontogenesis of this brain structure. Using BrdU labeling, we examined the fate of neuroblast progeny during the postembryonic development.

Short- and long-chain natural polyamines play specific roles in adult cricket neuroblast proliferation and neuron differentiation in vitro.

In the house cricket (Acheta domesticus) mushroom bodies, neurogenesis still occurs during adulthood. Using in vitro approaches, the respective roles of natural polyamines in neurogenesis were examined. Mushroom body neuroblast proliferation was assayed in organotypic culture using 5-bromo, 2'-deoxyuridine labeling.

c-Fos-related antigens in the central nervous system of an insect, Acheta domesticus.

Fos-related antigens (Fra) were detected in the nuclei of neurones in young adult Acheta domesticus female crickets by immunohistochemical analysis, using an antibody that recognizes the amino-acid sequence 127-152 of c-Fos protein. Specificity of Fra immunoreactivity was confirmed by Western blot analysis of nuclear extracts from neural tissues. A major immunoreactive doublet with an apparent molecular mass of 52,000/54,000 Da was detected in nuclear extracts.

Influence of environmental stimulation on neurogenesis in the adult insect brain.

Mushroom bodies are the main integrative structures of insect brain. They receive sensory information from the eyes, the palps, and the antennae. In the house cricket, Acheta domesticus, a cluster of mushroom body neuroblasts keeps producing new interneurons during an insect's life span.

Dual effect of ecdysone on adult cricket mushroom bodies.

Mushroom bodies, which are the main integrative centre for insect sensorial information, play a critical role in associative olfactory learning and memory. This paired brain structure contains interneurons grouped in a cortex, sending their axons into organized neuropiles. In the house cricket (Acheta domesticus) brain, persistent neuroblasts proliferate throughout adult life.

Immunocytochemical mapping of an RDL-like GABA receptor subunit and of GABA in brain structures related to learning and memory in the cricket Acheta domesticus.

The distribution of putative RDL-like GABA receptors and of gamma-aminobutyric acid (GABA) in the brain of the adult house cricket Acheta domesticus was studied using specific antisera. Special attention was given to brain structures known to be related to learning and memory. The main immunostaining for the RDL-like GABA receptor was observed in mushroom bodies, in particular the upper part of mushroom body peduncle and the two arms of the posterior calyx.

Specific requirement of putrescine for the mitogenic action of juvenile hormone on adult insect neuroblasts.

Persistent neurogenesis in an adult insect brain was recently shown to be stimulated by juvenile hormone (JH). This morphogenetic hormone was also shown to act on polyamine biosynthesis. To analyze the possible involvement of polyamines in the neurogenic action of JH, two series of experiments were carried out with adult female crickets, Acheta domesticus: (i) inhibition of the first key enzyme in polyamine biosynthesis, ornithine decarboxylase, with alpha-difluoromethylornithine (alpha-DFMO), and examination of the effects of this treatment on the neuroblast proliferation response to JH; and (ii) examination of the effects of putrescine supplementation on the mitotic index of JH-deprived and alpha-DFMO-treated females.

Casein kinase II activity in the brain of an insect, Acheta domesticus: characterization and hormonal regulation.

This study documented casein kinase II (CK II) activity in Acheta domesticus brain using specific antibodies and its regulation by polyamines. In control animals a transient decrease in CK II activity at day 3 after imaginal moult was observed in the brain but not in the fat body. If deprived of ecdysone by ovariectomy a different pattern was observed, with CK II activity being significantly higher on days 3 and 4 after emergence.

Inhibition of polyamine biosynthesis alters oviposition behavior in female crickets.

The role of polyamines in the expression of cricket oviposition, a juvenile hormone-dependent behavior, was investigated using a specific inhibitor of ornithine decarboxylase, alpha-difluoromethylornithine (alpha-DFMO). The fat body of treated female house crickets (Acheta domesticus) did not show any putrescine and presented reduced levels of spermidine, whereas spermine titres were significantly enhanced. In nervous tissue, alpha-DFMO did not affect spermine titres but induced a severe drop in spermidine levels.

Neurogenesis in adult insect mushroom bodies.

The occurrence of neurogenesis in mushroom bodies of adult insects belonging to several orthopteroid and coleopteran families is described. Using injections of 5-bromo, T2'-deoxyuridine, we showed that neuroblasts, which are progenitors of Kenyon cells during preimaginal instars, continue to divide in adult Acheta domesticus. Their progeny constitute a central column in mushroom body cortices of 3-week-old females.

Ovaries and regulation of juvenile hormone titer in Acheta domesticus L. (Orthoptera).

A study was performed on females Acheta domesticus to examine the effects of various experimental conditions on the ovarian physiology. Using a radioimmunoassay to determine juvenile hormone (JH) titers as well as in vitro JH biosynthesis, we observed that retention of mature follicles in egg-retaining females, i.e.

In vivo application of HRP crystals: a new and efficient method for tracing neural connections in insects.

Solid HRP pellets prepared with a 2.5% Triton X-100 aqueous solution were implanted either into corpora allata or applied onto neurohemal organs of a cricket. The method presents two advantages: it allows one to perform "in vivo" instead of "in vitro" experiments, and detergent HRP pellets are easy to manipulate.

Ultrastructural dynamics of the corpus allatum of Choleva angustata Fab. (Coleoptera, Catopidae).

The ultrastructure of the corpora allata (CA) during postembryonic stages of Choleva angustata Fab. shows cyclic changes, in particular regarding the endoplasmic reticulum and the mitochondria. During the last larval instar, at the short transitory period which follows the cessation of alimentation, we observed a highly unusual appearance of the CA, characterized by intensive vacuolization.

[Ultrastructural changes in the corpora allata of the last larval instar of Choleva angustata Fab. (Catopidae). The effect of fasting, with or without ecdysterone].

Fasting experiments show striking changes at the ultrastructural level in the corpora allata of the last larval instar of Choleva angustata Fab: increase of the glandular volume and development of the smooth reticulum. These findings suggest that fasting leads to a continuous activity of the corpora allata.

[Ultrastructural development of the corpora allata during the last larval stage of Choleva angustata Fab. (Coleoptera Catopidae of the subfamily Catopinae)].

The ultrastructure of the corpora allata of the last larvar instar of Choleva angustata Fab. was studied. In normal development a complex pattern of changes in the ultrastructure of the corpora allata occurs in relation to the larval age in the active and inactive stages.