Éva Fekete

The mechanism of evagination of imaginal discs of Drosophila melanogaster - II. Studies on trypsin-accelerated evagination

SummaryThe effects of trypsin treatment on thein vitro evagination of imaginal discs under different conditions are investigated. It is found that trypsin accelerates the evagination of dises which have previously been exposed to ecdysonein vivo orin vitro. Substances which inhibit ecdysone-induced (unaccelerated) evagination, such as Cytochalasin B, Concanavalin A and Mycostatin also inhibit trypsin-accelerated evagination.On the cellular level, evagination is associated with the flattening of the disc cells. However, immature discs (i.e., those which have not been exposed to ecdysone) and discs pretreated with Cytochalasin B do not evaginate in response to trypsin even though pronounced cell flattening occurs. Cell flattening is an energy requiring process since it does not occur in response to trypsin treatment in the presence of oligomycin or nitrogen We conclude that cell flattening is an active process that takes place during evagination but which does not itself produce evagination. An alternative mechanism for evagination may involve cell rearrangement. Trypsinization could facilitate both cell flattening and cell rearrangement by reducing intercellular adhesiveness.

Neuromedin C microinjected into the amygdala inhibits feeding

Bombesin-like peptides including gastrin releasing peptide and neuromedin C are known to inhibit feeding. Bombesin receptors have been found in moderate to high densities in the amygdaloid body, which is essentially involved in the regulation of feeding and body weight. In the present experiments neuromedin C (15, 30, and 60 ng), a carboxyterminal decapeptid fragment of gastrin releasing peptide, was bilaterally microinjected into the central part of the amygdala in ad libitum fed male CFY rats. Food intake was measured every 5 min for 30 min and also 6 min following neuromedin C or vehicle microinjections. Fifteen nanograms neuromedin C significantly suppressed liquid food consumption for 5 min and 30 ng for 25 min. However, 60 ng was not effective. Neuromedin C effects were blocked by prior application of the bombesin receptor antagonist [Leu(13)-psi(CH(2)NH)-Leu(14)]-bombesin. Neuromedin C treatment increased latency to feeding, decreased food intake, decreased the time spent feeding and their ratio, the number and the duration of feeding episodes during the first 5 min, without modifying body temperature or stereotype activity. Results indicate that neuromedin C may decrease the efficiency of feeding and that activation of bombesin receptors in the central amygdala may reduce appetite.

Gastrin-releasing peptide microinjected into the amygdala inhibits feeding

Bombesin (BN)-like peptides including gastrin-releasing peptide (GRP) are known to inhibit feeding. In the amygdaloid body BN receptors have been found in moderate to high densities. The central part of the amygdala (ACE) is essentially involved in the regulation of feeding and body weight. In the present experiments GRP was injected into the ACE and liquid food intake, general behavioural activity, as well as core temperature, were examined in male CFY rats. Food intake was measured every 5 min for 30 min and at the 40th and the 60th min following GRP or vehicle microinjections. Bilateral application of 50, 100 or 150 ng GRP resulted in transient inhibition of food intake while bilateral injection of 25 or 300 ng GRP did not modify feeding. Effect of GRP was eliminated by prior application of BN receptor antagonist [Leu(13)-psi(CH(2)NH)-Leu(14)]BN. After GRP or vehicle treatments animals were video-monitored and food intake, the first meal latency (FML), intermeal intervals (IMI), the time spent feeding (FT), grooming, resting and exploration were analysed at 5-min intervals for 30 min. However, FML did not change after GRP, the first IMI increased and intake, FT and intake/FT significantly decreased during the first 5 min. Duration of resting gradually increased after GRP and animals spent less time with exploration after GRP treatment than after vehicle injection. These differences were significant during the 25-30-min period. In body temperature, no significant changes were observed. Our results show that GRP in the ACE inhibits feeding and that GRP may decrease the efficiency of eating and may act as a satiety signal.

Fullerenes in electron cyclotron resonance ion sources

Fullerene plasmas and beams have been produced in our electron cyclotron resonance ion sources (ECRIS) originally designed for other purposes. The ATOMKI-ECRIS is a traditional ion source with solenoid mirror coils to generate highly charged ions. The variable frequencies NIRS-KEI-1 and NIRS-KEI-2 are ECR ion sources built from permanent magnets and specialized for the production of carbon beams. The paper summarizes the experiments and results obtained by these facilities with fullerenes. Continuous effort has been made to get the highest C60 beam intensities. Surprisingly, the best result was obtained by moving the C60 oven deep inside the plasma chamber, very close to the resonance zone. Record intensity singly and doubly charged fullerene beams were obtained (600 and 1600nA, respectively) at lower C60 material consumption. Fullerene derivatives were also produced. We mixed fullerenes with other plasmas (N, Fe) with the aim of making new materials. Nitrogen encapsulated fullerenes (mass: 720+14=734) we...

Investigation of Iron‐Fullerene Mixture Plasmas in ECR Discharge

Abstract Fullerene+iron (C60+Fe) mixture plasmas were produced and studied in the ECR ion source of ATOMKI. The two main components of the plasma were obtained by different filament ovens. In this series of measurements we concentrated on the maximum ratio of C58 (damaged fullerene) in the plasma. C58 is less stable than C60 and the probability to form new materials is higher. Using this method we produced molecules of mass M=752 both in single‐ and double‐charged states with beam intensities of 8 · 10−10A and 2 · 10−10A, respectively. We identified this beam as a mixture of FeC58, O2C60 and CO2C59, while the experiment did not give information on the exact location of the iron and oxygen in the carbon ball.

Bombesin microinjection into the basolateral amygdala influences feeding behavior in the rat

It has been demonstrated that the basolateral amygdala (ABL) represents a satiety mechanism. Experimental data indicate that peripheral or central applications of neuropeptide bombesin (BN) and BN-like peptides inhibit feeding. Since the amygdala (AMY) is rich in BN-like immunoreactive elements, the present study was performed to determine whether 10 or 40 ng doses of BN microinjected bilaterally into the ABL could modify solid food intake. Twenty nanograms of BN (10 ng per injection site) in 24-h deprived rats caused transient inhibition of food intake and 80 ng resulted in a significant reduction of food consumption for 1 h. This inhibitory effect of BN on feeding was eliminated by prior BN antagonist treatment. Results of behavioral tests showed that BN microinjections into the ABL specifically reduced food intake without altering behavioral patterns or influencing the body temperature. Present results suggest that BN-like peptides may act as a complex satiety signal in the ABL.

Imaginal disc ribosomal proteins of D. melanogaster

SummaryThe ribosomal proteins from undifferentiated imaginal discs of Drosophila melanogaster were analyzed by two-dimensional gel electrophoresis and compared with the ribosomal protein pattern of adult flies. It is shown that the ribosomal proteins from these discs are qualitatively identical with those of adult flies except that two acidic proteins are missing in the discs. This heterogeneity is discussed in terms of the functional roles these two proteins may carry in connection with disc differentiation.

Electrochemical dissolution of aluminium in electrocoagulation experiments

Six experiments are presented to highlight important features of aluminium dissolution when used in electrocoagulation procedure employed to remove oily contaminations from water. First, using a common oil-in-water emulsion: diluted milk, we show that the electrochemically generated coagulant ions are active only in the first few seconds following their generation—hence, the electrocoagulation cells’ construction should promote the mixing of the nascent Al colloid with the water phase. For this reason, the use of the narrow-gap cells is suggested. Second, in experiments with Al-Al electrode pairs and dilute, neutral, unbuffered, aqueous solutions we (i) estimate the maximum amount of Al dissolution on the cathode and (ii) show how the rate of Al dissolution changes with frequency if the cell voltage polarity is alternating.

Electrochemical methods to determine the corrosion rate of a metal protected by a paint film

Two electrochemical methods which allow the determination of the rate of underpaint corrosion processes are presented. One of them is an alternating current method based on the nonlinearity of the Faradaic process. The other one is based on the electrochemical potential noise of metal dissolution. These methods permit the study of the corrosion protection properties of primers containing anticorrosive pigments.

Application of compact electron cyclotron resonance ion source

The compact electron cyclotron resonance (ECR) ion source with a permanent magnet configuration (Kei2 source) has been developed at National Institute of Radiological Sciences for a new carbon therapy facility. The Kei2 source was designed for production of C(4+) ions; its performance such as beam intensity and stability has already reached the medical requirements. Therefore, the prototype development of the source for medical use is essentially finished. Recently, we have started a few studies on other applications of the source. One is the production of fullerenes in the ECR plasma and modified fullerenes with various atoms for new materials. A second application is the production of multiply charged ions (not only carbon) for ion implantation. In this paper, some basic experiments for these applications are reported.