The initiation of pupariation in Drosophila: dependence on growth of the imaginal discs

Development ◽  
1980 ◽  
Vol 57 (1) ◽  
pp. 155-165
Author(s):  
P. Simpson ◽  
P. Berreur ◽  
J. Berreur-Bonnenfant
Keyword(s):  
Larval Development ◽  
Imaginal Discs ◽  
Clonal Analysis ◽  
Larval Life ◽  
Lethal Mutations ◽  
Heat Treated

Regeneration was induced in the imaginal discs in situ following lesions caused by heatsensitive cell-lethal mutations. A clonal analysis of this event demonstrated that the subsequent delay in pupariation was correlated with the amount of extra growth that occurred during the regeneration. Pupariation of heat-treated gynandromorphs bearing the mutations was also retarded, and the duration of larval development increased with greater amounts of mutant tissue, it was therefore correlated with the extent of the lesions in the imaginal discs. Elimination of entire imaginal discs, or the presence of very small amounts of lethal tissue, did not result in prolonged larval life.

Influence of ion-milling on the T2 phase in Al-2.5%Li-2.5%Cu alloy

1989 ◽  
Vol 47 ◽  
pp. 288-289
Author(s):  
J. R. Reed ◽  
D. J. Michel ◽  
P. R. Howell
Keyword(s):  
Thin Foil ◽  
Icosahedral Symmetry ◽  
Ion Milling ◽  
Cu Alloy ◽  
Thin Foils ◽  
Heat Treated ◽  
Aluminum Solid Solution ◽  
In Situ Heating ◽  
The Stability

The Al6Li3Cu (T2) phase, which exhibits five-fold or icosahedral symmetry, forms through solid state precipitation in dilute Al-Li-Cu alloys. Recent studies have reported that the T2 phase transforms either during TEM examination of thin foils or following ion-milling of thin foil specimens. Related studies have shown that T2 phase transforms to a microcrystalline array of the TB phase and a dilute aluminum solid solution during in-situ heating in the TEM. The purpose of this paper is to report results from an investigation of the influence of ion-milling on the stability of the T2 phase in dilute Al-Li-Cu alloy.The 3-mm diameter TEM disc specimens were prepared from a specially melted Al-2.5%Li-2.5%Cu alloy produced by conventional procedures. The TEM specimens were solution heat treated 1 h at 550°C and aged 1000 h at 190°C in air to develop the microstructure. The disc specimens were electropolished to achieve electron transparency using a 20:80 (vol. percent) nitric acid: methanol solution at -60°C.

The missing links: larval and post-larval development of the ascoglossan opisthobranch Elysia viridis

2000 ◽  
Vol 80 (6) ◽  
pp. 1087-1094 ◽  
Author(s):  
Cynthia D. Trowbridge
Keyword(s):  
Larval Development ◽  
Growth Rates ◽  
Shell Length ◽  
Larval Growth ◽  
Model Organism ◽  
Larval Life ◽  
Codium Fragile ◽  
Planktotrophic Larvae ◽  
Algal Diet ◽  
Better Than

The stenophagous ascoglossan (=sacoglossan) opisthobranch Elysia viridis has long been a model organism for the study of endosymbiosis or kleptoplasty as well as one of the few herbivores to consume the introduced green macroalga Codium fragile on European shores. Larval and post-larval dynamics of the ascoglossan were investigated. Planktotrophic larvae of E. viridis grew at 5–10 μm d−1 (shell length) at 15°C on a unicellular algal diet (the cryptophyte Rhodomonas baltica); larvae became competent one month post-hatching. Effective feeding and chloroplast acquisition typically started within 2–3 d of metamorphosis. Slugs grew about 8 mm in the first month of post-larval life. During this period, juveniles held in the light did not grow faster or survive better than conspecifics held in the dark; thus, functional kleptoplasty did not occur during first three weeks of benthic life. While larval growth rates and the nature of metamorphic cues are consistent with those of many other opisthobranch species with planktotrophic larvae, measures of post-larval growth—particularly as it pertains to kleptoplasty—is a new contribution to opisthobranch biology.

Neurogenesis in the thoracic neuromeres of two crustaceans with different types of metamorphic development

1998 ◽  
Vol 201 (17) ◽  
pp. 2465-2479 ◽  
Author(s):  
S Harzsch ◽  
J Miller ◽  
J Benton ◽  
RR Dawirs ◽  
B Beltz
Keyword(s):  
Embryonic Development ◽  
Larval Development ◽  
Neuronal Development ◽  
Temporal Patterns ◽  
Homarus Americanus ◽  
Spider Crab ◽  
Larval Life ◽  
Larval Stages ◽  
Metamorphic Development ◽  
Embryonic And Larval Development

The mode of embryonic and larval development and the ethology of metamorphosis in the spider crab and the American lobster are very different, and we took advantage of this to compare neuronal development in the two species. The goals of this study were to discover whether the differences in the maturation of the neuromuscular system in the pereopods and the metamorphic changes of motor behavior between the two species are reflected at the level of the developing nervous system ('neurometamorphosis'). Furthermore, we wanted to broaden our understanding of the mechanisms that govern neuronal development in arthropods. Proliferation of neuronal stem cells in thoracic neuromeres 4-8 of the lobster Homarus americanus and the crab Hyas araneus was monitored over the course of embryonic and larval development using the in vivo incorporation of bromodeoxyuridine (BrdU). Neuropil structure was visualized using an antibody against Drosophila synapsin. While proliferation of neuronal precursors has ceased when embryogenesis is 80 % complete (E80%) in the lobster thoracic neuromeres, proliferation of neuroblasts in the crab persists throughout embryonic development and into larval life. The divergent temporal patterns of neurogenesis in the two crustacean species can be correlated with differences in larval life style and in the degree of maturation of the thoracic legs during metamorphic development. Several unusual aspects of neurogenesis reported here distinguish these crustaceans from other arthropods. Lobsters apparently lack a postembryonic period of proliferation in the thoracic neuromeres despite the metamorphic remodeling that takes place in the larval stages. In contrast, an increase in mitotic activity towards the end of embryonic development is found in crabs, and neuroblast proliferation persists throughout the process of hatching into the larval stages. In both E20% lobster embryos and mid-embryonic crabs, expression of engrailed was found in a corresponding set of neurons and putative glial cells at the posterior neuromere border, suggesting that these cells have acquired similar specific identities and might, therefore, be homologous. None of the BrdU-labeled neuroblasts (typically 6-8 per hemineuromere over a long period of embryogenesis) was positive for engrailed at this and subsequent stages. Our findings are discussed in relation to the spatial and temporal patterns of neurogenesis in insects.

Rumen protection of heat-treated soybean proteins

1992 ◽  
Vol 72 (1) ◽  
pp. 71-81 ◽  
Author(s):  
B. M. Mosimanyana ◽  
D. N. Mowat
Keyword(s):  
Soybean Meal ◽  
Block Design ◽  
Soybean Proteins ◽  
Passage Rate ◽  
Heat Treated ◽  
Ruminal Degradation ◽  
In Situ Degradation ◽  
Exit Temperature ◽  
Forced Air

The effects of processing variables on soybean crude protein (CP) ruminal degradation were investigated. Soybean meal (SBM) was heated in a forced-air oven (90 °C, 1 h) with blood (0, 5, 10 and 20% dry matter) and/or xylose (3 mol mol−1 SBM-blood lysine) in a randomized complete block design. In another experiment, whole soybeans were utilized using the following treatments: raw; roasted (in Gem Co. unit exit temperature 150 °C) and steeped for 0 or 2 h; roasted, flaked (exit temperature 111 °C) and steeped for 0, 1, 2, 3 h or 1 h with 4% xylose and/or 10% blood. Solubility of SBM CP was reduced (P < 0.01) by the addition of xylose, without adverse effects on pepsin-digestible CP and acid detergent insoluble nitrogen. In situ degradation of CP (EDCP), assuming a passage rate of 5% h−1, of SBM was reduced by the addition of blood (P < 0.05) and particularly xylose (P < 0.01). Soybean CP solubility was reduced (P < 0.01) by roasting and flaking (65.6 vs. 17.6% total CP). Not flaking the roasted beans further reduced (P < 0.01) CP solubility (to 10.4%) probably due to less rapid cooling. The EDCP of raw soybeans (87.6%) was reduced by roasting (64.2%), steeping whole (57.6%) or flaked (61.1%) beans. These data support xylose to effectively reduce ruminal degradation of SBM and simple steeping (1 h) with or without flaking to further reduce EDCP of roasted soybeans. Key words: Soybean meal, soybeans, xylose, blood, steeping, protein degradation

scholarly journals Synthesis and Characterization of Lixfepo4/C-Ppy Composite Cathode Material with Excess of Li+ Doping

2019 ◽  
Vol 9 (2) ◽  
pp. 5254-5257
Keyword(s):  
Composite Cathode ◽  
Chemical Precipitation ◽  
Polymerization Process ◽  
Step Method ◽  
Xrd Pattern ◽  
Li Doping ◽  
Unit Cell Size ◽  
Transmission Electron ◽  
Heat Treated

In-situ Polypyrrole (PPy) coating was performed on the surface of LixFePO4 /C (x=0.95 to 1.20) particles using iron (III) tosylate as oxidizer. The composite material LixFePO4 /C (x=0.95 to 1.20) was synthesized by two step method. FePO4 /polyaniline particles were first synthesized by chemical precipitation and were further heat treated with lithium acetate and sucrose under reduced atmosphere. XRD pattern confirms that Li+ addition to LiFePO4 has increased interplaner spacing and of the unit cell size. Impurity phase appears with x=1.15 and 1.20 which further disappears after polymer coating. After polymerization process the XRD pattern shows Li0.05FePO4 and LiFePO4 phases and both the phases have same electrochemical behavior. Morphology of the LixFePO4 /C and LixFePO4 /C-PPy was studied by using FE-SEM and it was found that particles are spherical with size range below 200nm. Transmission Electron Microscope (TEM) also confirms that LixFePO4 /C isolated particles were well encapsulated within the polymer matrix

The Effects of Thermal History on Toughness of Ni-Based Corrosion Resistant Alloys During In-Situ Hydrogen Charging

2021 ◽  
Author(s):  
Michelle Kent ◽  
Kip Findley
Keyword(s):  
Thermal History ◽  
Potential Drop ◽  
Heat Treatments ◽  
Alloy 718 ◽  
Unstable Crack ◽  
Heat Treated ◽  
Δ Phase ◽  
Incremental Step ◽  
M23c6 Carbides

Abstract Hydrogen embrittlement (HE) susceptibility was investigated for Alloy 718 and Alloy 945X specimens heat treated to a set of conditions within the specifications of API Standard 6ACRA. Heat treatments were selected to simulate the potential variation in thermal history in thick sections of bar or forged products and produce various amounts of discontinuous grain boundary δ phase in Alloy 718 and M23C6 carbides in Alloy 945X, while maintaining a constant hardness in the range of 35-45 HRC for Alloy 718 and 34-42 HRC for Alloy 945X. Time-temperature-transformation (TTT) diagrams and experimentation were used to select a set of heat treatments containing no δ phase, a small quantity of δ, and a larger quantity of δ in Alloy 718. The presence of δ phase has not been verified for the moderate condition. A similar approach was taken regarding M23C6 carbides in Alloy 945X. Incremental step loading (ISL) tests were conducted under in-situ cathodic charging on circular notch tensile (CNT) specimens in a 0.5 M H2SO4 solution. During the test, the direct current potential drop (DCPD) was measured across the notch to determine the stress intensity associated with unstable crack growth. Results indicate that even very small quantities of δ phase in Alloy 718 are detrimental to HE resistance. Both Alloy 718 and Alloy 945X show decreases in HE resistance with aging, with a greater degradation in Alloy 718.

Transcription of the segment-polarity gene wingless in the imaginal discs of Drosophila, and the phenotype of a pupal-lethal wg mutation

Development ◽  
1988 ◽  
Vol 102 (3) ◽  
pp. 489-497 ◽  
Author(s):  
N.E. Baker
Keyword(s):  
In Situ Hybridization ◽  
Imaginal Discs ◽  
Apical Cytoplasm ◽  
Segment Polarity ◽  
Disc Cells ◽  
Segment Polarity Gene ◽  
Drosophila Embryos ◽  
Polarity Gene

Wingless (wg) is a segment-polarity gene in Drosophila which is related to the murine proto-oncogene int1. In Drosophila embryos, wg transcription defines part of each parasegment. In situ hybridization shows that wg is also expressed in the imaginal discs which give rise to the adult during metamorphosis. Transcripts are localized in the apical cytoplasm of disc cells, and accumulate in different patterns in dorsal and ventral discs. The wgCX3 mutation produces morphological defect in the adult structures derived from these imaginal discs. The results show that wg is involved in the development of the adult, as well as the embryo, but that the imaginal discs do not express this segment-polarity gene in an identical pattern to the embryonic segments.

Wingless induces transdetermination in developing Drosophila imaginal discs

Development ◽  
1995 ◽  
Vol 121 (5) ◽  
pp. 1263-1272 ◽  
Author(s):  
L. Maves ◽  
G. Schubiger
Keyword(s):  
Molecular Level ◽  
Ectopic Expression ◽  
Imaginal Discs ◽  
Developmental Studies ◽  
New Approach ◽  
Cell Determination ◽  
Disc Cells ◽  
The Subject ◽  
Insight Into

Drosophila imaginal discs, the precursors of the adult fly appendages, have been the subject of intensive developmental studies, particularly on cell determination. Cultured disc fragments are recognized not only for the ability to maintain their determined state through extra cell divisions but also for the ability to transdetermine, or switch to the determined state of a different disc. An understanding of transdetermination at a molecular level will provide further insight into the requirements for maintaining cell determination. We find that ectopic expression of the Drosophila gene wingless induces transdetermination of foreleg imaginal disc cells to wing cells. This transdetermination occurs in foreleg discs of developing larvae without disc fragmentation. The in situ-transdetermining cells localize to the dorsal region of the foreleg disc. This wingless-induced transdetermination event is remarkably similar to the leg-to-wing switch that occurs after leg disc culture. Thus we have identified a new approach to a molecular dissection of transdetermination.

scholarly journals Accidentally catching of the catfish Lophiosilurus alexandri (Steindachner, 1876) larvae in aquariums with different colors

2019 ◽  
Vol 79 (4) ◽  
pp. 612-616
Author(s):  
M. M. Pedreira ◽  
D. C. Costa ◽  
M. Schorer
Keyword(s):  
Larval Development ◽  
Blue Light ◽  
High Mortality ◽  
Standard Length ◽  
Larval Life ◽  
Visual Ability ◽  
Final Development ◽  
Good Contrast

Abstract The aim of this study was to evaluate the effect of different colors in development and survival of catfish Lophiosilurus alexandri larvae, as well as over the visual ability of the handler. Larvae were placed in 5 L-aquariums at a density of 7 larvae L-1 , and aquariums had different colors, and were: green and blue (light colors); brown and black (dark colors). The final development; survival, total and standard length, weight and biomass of the larvae were similar in all colored aquaria. The highest mortality occurred during the first days after hatching, declining over the period, when it is observed the larval development, indicating that care should be necessary in the first few days. During cleaning handling, the accidental catch of larvae was higher in black aquariums. In the first days of life, due to the fragility of the larvae, it is possible to verify that between the second and third day occur the greatest mortalities. The number of accidentally captured larvae was lower than the mortality, suggesting that the high mortality in early larval life is not influenced by the handler management. The catfish L. alexandri larvae should be cultivated in aquariums that allow a good contrast between the larvae and the background, to avoid accidental capture of larvae by the handler. It is suggested to avoid the use of dark and black aquariums.

Effect of heat treatment and heat treatment in combination with lignosulfonate on in situ rumen degradability of canola cake crude protein, lysine, and methionine

2020 ◽  
Vol 100 (1) ◽  
pp. 165-174 ◽  
Author(s):  
Piotr Micek ◽  
Katarzyna Słota ◽  
Paweł Górka
Keyword(s):  
Heat Treatment ◽  
High Temperature ◽  
Crude Protein ◽  
Dry Matter ◽  
Increased Temperature ◽  
Heat Treated ◽  
Cold Pressed ◽  
Temperature Heating ◽  
High Temperature Heating

The aim of this study was to determine the effect of heat treatment alone or in combination with the addition of lignosulfonate (LSO3) on canola cake protein, lysine, and methionine degradation in the rumen. Cold-pressed canola cake was left untreated, heated at 90, 110, 130, or 150 °C, or processed with 5% of LSO3 (in dry matter) and then heated. Effective rumen degradability of crude protein (CP), lysine, and methionine was less for treated than untreated canola cake (P < 0.05) and decreased with increased temperature of heating, but particularly when canola cake was heated at 150 °C (quadratic, P < 0.01). In general, effective rumen degradability of CP, lysine, and methionine was less for canola cake heated at 130 °C in combination with LSO3 compared with canola cake heat treated only (quadratic × LSO3 interaction, P ≤ 0.07). Results of this study indicate that high temperature heating (130 °C or greater for 60 min) may be necessary to protect canola cake protein from degradation in the rumen, and the combination of heat treatment and LSO3 may be more effective in protecting canola cake protein, lysine, and methionine from degradation in the rumen than the use of heat treatment only.

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