Alterations in high-affinity binding characteristics and levels of opioids in invertebrate ganglia during aging: Evidence for an opioid compensatory mechanism

In Mytilus and Leucophaea the high-affinity binding site density is significantly lower in old animals than in young animals, whereas the low-affinity site density remains unchanged. In Mytilus the estimated met-enkephalin and met-enkephalin-Arg6-Phe7 levels are significantly higher in old than in young animals. In Leucophaea only the met-enkephalin level can be determined, and it is also higher in old animals. The decrease in the high-affinity binding site density and the corresponding increase in endogenous enkephalin levels suggest the existence of an opioid compensatory mechanism associated with the aging process. In Mytilus there is a demonstrated decrease with age in intraganglionic dopamine levels in response to applied opiates. In addition, the inhibition of dopamine-stimulated adenylate cyclase activity by opiates also decreases in older animals. In Leucophaea the sex difference in opioid binding densities diminishes with age.     

Effects of chronic alcoholism on the amygdaloid complex. A study in human and rats

The effect of chronic alcoholism on the amygdaloid complex was studied in 16 humans and 10 rats. Eighteen patients whose death was due to extraneural causes were selected as controls with 3 rats. The alcoholic cases, in addition to the data collected in their clinical history, showed, microscopically confirmed, liver cirrhosis or steatosis. The alcoholics and controls were divided into 4 groups: 35-44 years old (4 cases), 45-54 (5 cases), 55-64 (5 cases) over 65 (2 alcoholics and 4 controls). The alcoholic ingestion in the rats (Wistar, 10 weeks old) was 3 ml at a concentration of 30% in water solution administered by esophagic intubation, for 48 (5 rats) or 58 weeks (5 rats). To judge the state of the amygdaloid nuclei, a neuronal count and caryometry were carried out. The numerical data obtained in this study were analyzed statistically. The results in humans have paralleled those obtained in rats and the behaviour of the different nuclei of the amygdala was uniform and can be summarized as follows: 1) ethanol provoked a prominent and early loss of neurons, and 2) the remainder of non-affected neurons did not react in order to compensate for this neuronal loss.     

Control of Nitrogenase mRNA Levels by Products of Nitrate Assimilation in the Cyanobacterium Anabaena sp. Strain PCC 7120

Nitrate inhibited nitrogenase synthesis and heterocyst development in the cyanobacterium Anabaena sp. strain PCC 7120. Inhibition of dinitrogen fixation by nitrate did not take place, however, in nitrate reductase-deficient derivatives of this strain. Hybridization of total RNA isolated from cells grown on different nitrogen sources with an internal fragment of the nifD gene showed that regulation of nitrogenase activity by nitrate is exerted through a negative control of the nitrogenase mRNA levels.     

Clomipramine actions on firing rate in septal nuclei of the rat are not related to anaesthesia (urethane).

An increased firing rate in lateral septal nuclei (LSN) appears in urethane-anesthetized rats after several acute drug and non-drug human antidepressant treatments. A still more pronounced increase in firing rate is produced in LSN after clomipramine (CMI) long-term treatment. In spite of urethane is a widely used anesthetic for single unit extracellular recordings, it modifies evoked potentials wave-form. Therefore, present study discards urethane interaction with CMI in LSN single unit extracellular recordings. CMI was acutely injected (1.25 mg/kg: IP) either to urethane-anesthetized, or non-anesthetized encephale-isolé rats. The CMI treated groups showed higher rates of firing in LSN regardless of the use of general anesthesia during recordings. Another group of urethane-anesthetized rats received intracerebroventricular (ICV) microinjections of CMI (100 micrograms/10 microliters/1 min). An amount of 42.8% of LSN-recorded neurons responded with a long-lasting increased firing rate. Results discard urethane and CMI interactions. Additionally, systemic actions of CMI on firing rate of LSN are reproduced by ICV/route microinjections.     

High-level expression of a tobacco chitinase gene in Nicotiana sylvestris. Susceptibility of transgenic plants to Cercospora nicotianae infection

Endochitinases (E.C. 3.2.14, chitinase) are believed to be important in the biochemical defense of plants against chitin-containing fungal pathogens. We introduced a gene for class I (basic) tobacco chitinase regulated by Cauliflower Mosaic Virus 35S-RNA expression signals into Nicotiana sylvestris. The gene was expressed to give mature, enzymatically active chitinase targeted to the intracellular compartment of leaves. Most transformants accumulated extremely high levels of chitinase-up to 120-fold that of non-transformed plants in comparable tissues. Unexpectedly, some transformants exhibited chitinase levels lower than in non-transformed plants suggesting that the transgene inhibited expression of the homologous host gene. Progeny tests indicate this effect is not permanent. High levels of chitinase in transformants did not substantially increase resistance to the chitin-containing fungus Cercospora nicotiana, which causes Frog Eye disease. Therefore class I chitinase does not appear to be the limiting factor in the defense reaction to this pathogen.