Achievements and perspectives in yeast acetic acid-induced programmed cell death pathways

The use of non-mammalian model organisms, including yeast Saccharomyces cerevisiae, can provide new insights into eukaryotic PCD (programmed cell death) pathways. In the present paper, we report recent achievements in the elucidation of the events leading to PCD that occur as a response to yeast treatment with AA (acetic acid). In particular, ROS (reactive oxygen species) generation, cyt c (cytochrome c) release and mitochondrial function and proteolytic activity will be dealt with as they vary along the AA-PCD time course by using both wild-type and mutant yeast cells. Two AA-PCD pathways are described sharing common features, but distinct from one another with respect to the role of ROS and mitochondria, the former in which YCA1 acts upstream of cyt c release and caspase-like activation in a ROS-dependent manner and the latter in which cyt c release does not occur, but caspase-like activity increases, in a ROS-independent manner.     

Palytoxin Induces Functional Changes of Anion Transport in Red Blood Cells: Metabolic Impact

Palytoxin (PTX) is classified as one of the most powerful marine biotoxins (of high molecular weight and no protein origin) because it is able to interact strongly with important cellular structures influencing their function in different biological processes. This study of the effects of PTX on red blood cells (RBC) extends the knowledge about its toxicity, which concerns not only the well-known action on Na(+)/K(+)-ATPase but also band 3 protein (B3 or AE1), the role of which is essential for anion transport and for the structure, function, and metabolic integrity of the erythrocyte. The effects of PTX on RBC can be summarized as follows: it alters the anionic flux and seriously compromises not only CO(2) transport but also the metabolic modulation centered on the oxy-deoxy cycle of hemoglobin; it stabilizes the plasma membrane by preventing lipid peroxidation; and its effect does not lead to activation of caspases 3 and 8. From what is reported in steps 2 and 3, and on the basis of the results obtained on hemolysis, methemoglobin levels, and phosphatase activity, an increase of the reducing power of the erythrocytes (RBC) in the presence of PTX clearly emerges. The results have enabled us to outline some metabolic adaptations induced in the RBC by PTX.     

Weather daily variation in winter and its effect on behavior and affective states in day-care children

This study aimed to analyze the impact of winter weather conditions on young children’s behavior and affective states by examining a group of 61 children attending day-care centers in Florence (Italy). Participants were 33 males, 28 females and their 11 teachers. The mean age of the children at the beginning of the observation period was 24.1 months. The day-care teachers observed the children’s behavioral and emotional states during the morning before their sleeping time and filled in a questionnaire for each baby five times over a winter period of 3 weeks. Air temperature, relative humidity, air pressure and solar radiation data were collected every 15 min from a weather station located in the city center of Florence. At the same time, air temperature and relative humidity data were collected in the classroom and in the garden of each day-care center. We used multilevel linear models to evaluate the extent to which children’s emotional and behavioral states could be predicted by weather conditions, controlling for child characteristics (gender and age). The data showed that relative humidity and solar radiation were the main predictors of the children’s emotional and behavioral states. The outdoor humidity had a significant positive effect on frustration, sadness and aggression; solar radiation had a significant negative effect only on sadness, suggesting that a sunny winter day makes children more cheerful. The results are discussed in term of implications for parents and teachers to improve children’s ecological environment.     

Cationic nucleopeptides as novel non-covalent carriers for the delivery of peptide nucleic acid (PNA) and RNA oligomers

Cationic nucleopeptides belong to a family of synthetic oligomers composed by amino acids and nucleobases. Their capability to recognize nucleic acid targets and to cross cellular membranes provided the basis for considering them as novel non-covalent delivery agents for nucleic acid pharmaceuticals. Herein, starting from a 12-mer nucleopeptide model, the number of cationic residues was modulated in order to obtain new nucleopeptides endowed with high solubility in acqueous medium, acceptable bio-stability, low cytotoxicity and good capability to bind nucleic acid. Two candidates were selected to further investigate their potential as nucleic acid carriers, showing higher efficiency to deliver PNA in comparison with RNA. Noteworthy, this study encourages the development of nucleopeptides as new carriers to extend the known strategies for those nucleic acid analogues, especially PNA, that still remain difficult to drive into the cells.     

PRODUCTION OF MUCILAGE BY THE ADRIATIC EPIPELIC DIATOM CYLINDROTHECA CLOSTERIUM (BACILLARIOPHYCEAE) UNDER NUTRIENT LIMITATION

The carbon partitioning of the epipelic diatom Cylindrotheca closterium (Ehrenberg) Reiman and Lewin isolated from the Adriatic Sea was studied in the laboratory under varying scenarios of nutrient limitation. Total number of cells, photosynthesis measured at 695 μmol photons·m ^{− 2}·s ^{− 1} irradiance (P_{695- μ mol}), chlorophyll ( a + c ) content, respiration, extracellular polymeric substances (EPS), total particulate carbohydrate (TPC), and dissolved carbohydrate were evaluated under nitrogen and phosphorus deficiencies in culture. The highest total number of cells was found in the control, whereas the nitrogen-limited treatment showed the lowest value. During the transition phase of growth, photosynthesis in the nitrogen-limited treatment was 3-fold lower than in the phosphorus-limited treatment and 4-fold lower than in the control. Differences in respiration rates and chlorophyll ( a + c ) content were even more marked. Dissolved carbohydrate remained the same in all the treatments, whereas during the transition and stationary phase, EPS presented the highest values under phosphorus limitation and the lowest in the control treatment. The production of EPS was closely linked to the periods of carbon assimilation (transition phase) in the nutrient depleted treatments, especially in the phosphorus-limited treatment. These results point out the relevance of the nutrient imbalance (nitrogen or phosphorus) in the production of EPS by the benthic or resuspended diatoms and suggest that these diatoms play an important role in nutrient-unbalanced systems like sediments or marine snow.     

Effect of the sex-linked dwarf gene on thyrotrophic and somatotrophic axes in the chick embryo

Plasma concentrations of thyroxine (T4), triiodothyronine (T3), reversed triiodothyronine (rT3), and insulin-like growth factors I and II (IGF-I, IGF-II) together with peripheral 5'-monodeiodination activity were measured in both normal and sex-linked dwarf embryos between day 14 of incubation and day 1 posthatch. Plasma T4 levels increased gradually during embryonic development while T3 concentrations remained low until day 20, when a sharp increase was observed. rT3 levels also increased from day 14 and dropped on day 20 when T3 levels started to increase. 5'-monodeiodination activity was high on day 14 of incubation, decreased thereafter, and showed an increase at the time of air sac penetration together with increased T3 levels. At this stage, differences between normal and dwarf embryos were observed; the latter had lower nonsignificant 5'-Monodeiodination activity and lower (P less than 0.01) plasma T3 levels. Plasma IGF-II levels were high during the whole embryonic period studied. Dwarf embryos had lower (P less than 0.05) IGF-II levels at the time of hatching. IGF-I levels were high on days 14 and 16, declined afterwards, and started to increase again around hatching. With the exception of T3 and IGF-II levels, introduction of the dwarf gene did not cause major changes in the hormonal parameters studied. This may explain the identical body weight at hatching.     

Fatty acid synthesis in vivo. Transfer of lipids from microsomes to other subcellular fractions of rat liver

At various times after the intraperitoneal injection of Na acetate-1-C¹⁴ to male Wistar rats, the labelled fatty acids are nonuniformely distributed among the lipids of liver microsomes, mitochondria and cell sap. The changes observed in the specific radioactivity of the neutral and phospholipids support the hypothesis that a transfer of these lipids takes place from the site of synthesis (endoplasmic reticulum) to mitochondria and cell sap. This phenomenon is probably responsible for the decline of microsomal fatty acids in favour of the mitochondrial and soluble fractions. In this connection, the deacylation-reacylation process does not seem to be involved.     

Episodic growth hormone secretion in the domestic fowl (Gallus domesticus): alpha adrenergic regulation

In animals the secretion of GH is characterized by a series of spontaneous peaks. The situation in avian species, however, is unknown. The present study examines this in the domestic fowl. Blood samples were obtained via a remote catheter at 5-min intervals from young male chickens. An episodic pattern of GH secretion was observed having an interpulse interval (frequency) of approximately 1 h. Episodic GH secretion was altered by peripheral administration of drugs which influence adrenergic function. Spontaneous GH peaks were not observed following the administration of (1) bis-(4-methyl-1-homopiperazinyl-thiocarbonyl) disulfide (FLA63) or diethyldithiocarbamate (DDC) (which blocks norepinephrine (NE) and epinephrine (E) synthesis by inhibiting dopamine-beta-hydroxylase), (2) phenoxybenzamine (an alpha 1-adrenergic antagonist) and (3) clonidine (an alpha 2-adrenergic agonist). Neither alpha-methyl-p-tyrosine, which blocks dopamine (DA), NE and E synthesis, nor yohimbine, a predominantly alpha 2-antagonist could completely suppress episodic GH secretion. These data support a role for NE/E, acting via alpha adrenergic receptors, in the control of epidosic GH secretion in the domestic fowl.