Effects of pneumogastric nerve stimulation and injection of a beta 2 stimulant (terbutaline) on the lipid composition of the alveolar lining fluid and on pulmonary compliance in the rat

The effects of vagal stimulation and of terbutaline injection on lipidic composition of alveolar fluid and pulmonary compliance were studied. Three groups of rats were used: control, after right vagus nerve stimulation, after 0.2 mg terbutaline injection. The lungs of the rats were isolated. We studied pulmonary pressure-volume curves with air and we measured pulmonary compliance. We realised an alveolar lavage to obtain alveolar lipids. We observed: Vagus nerve stimulation and beta 2 agonist significantly increased fatty acids of total lipids respectively by 52.5% and 25.5% and phospholipids, respectively by 43.6% and 25.7%. beta 2 agonist did not change fatty acid composition of total lipids and phospholipids. Right vagus nerve stimulation increased the percentage of palmitic acid in phospholipids and decreased the percentage of saturated fatty acids and of palmitic acid in total lipids. Terbutaline injection induced more significant changes in pressure-volume curves and in pulmonary compliance than right vagus nerve stimulation. Our results suggest that both vagal stimulation and beta 2 agonists increase lipid release in alveolar lining, but only vagal stimulation modifies the composition of these lipids. These modifications could be, at least in part, correlated with the changes observed in the pressure-volume curves.     

Arginine metabolism in insects. Role of arginase in proline formation during silkmoth development

1. Ornithine delta-transaminase (l-ornithine-2-oxo acid aminotransferase, EC 2.6.1.13) and Delta(1)-pyrroline-5-carboxylate reductase [l-proline-NAD(P) 5-oxidoreductase, EC 1.5.1.2] were demonstrated in fat-body and flight-muscle tissues of the silkmoth Hyalophora gloveri. Arginase (l-arginine ureohydrolase, EC 3.5.3.1) is also present in these tissues. 2. Arginase, ornithine transaminase and pyrroline-carboxylate reductase are generally considered to make up the catabolic pathway for the conversion of arginine into proline. The conversion of l-[U-(14)C]arginine into [(14)C]proline by intact fat-body tissue was used to show that the enzymes in insect fat body also function in this capacity. 3. Of the three enzymes of the catabolic pathway, only arginase increased during adult development and the increase coincided with the emergence of the winged adult moth. Since proline appears to be a major substrate utilized in insect flight metabolism, the increase in arginase activity at this stage suggests a major role for arginase in proline formation.     

Characterization of xanthans from selected Xanthomonas strains cultivated under constant dissolved oxygen

Seventeen wild-type Xanthomonas isolates were screened in terms of broth viscosity in shake-flasks. As culture conditions affect polymer characteristics, a fair comparison among isolates required their cultivation in a fermenter under controlled dissolved oxygen tension. Three isolates and a reference strain were studied. The mean molecular weights and molecular weight distributions of their xanthans were determined. Products showed different pyruvate (0.2–7%), acetate (5–10%) and proteinaceous nitrogen (1–3%) contents. The selected isolates exhibit properties which could improve xanthan gum production and some could be used to produce polymers with specific characteristics.     

Effect of hosts and parasite density on the egg parasiteTrichogramma pretiosum [Hym.: Trichogrammatidae]

When females ofTrichogramma pretiosum Riley were confined with host eggs at a density of 2/150 eggs, they produced 12 times more female progeny on eggs of potato tuber moth than on eggs ofHeliothis armigera (Hübner) and 13,6 times more on eggs ofSitotroga cerealella (Olivier) than on eggs ofHeliothis. At a density of 4/150 eggs, the correspondent figures were 13 and 8 times. The percentage emergence fromHeliothis eggs was from 0,29 to 0,14 times as great as from tuber moth orSitotroga. From 15 to 140 times more runts were observed amongTrichogramma fromHeliothis eggs than among those from tuber moth eggs and 8 times more thant among those fromSitotroga eggs. This may explain the low recoveries in South Africa ofT. pretiosum in eggs ofH. armigera collected in cotton fields after mass liberation of the parasite. An increase in parasite density from 1/300 eggs to 16/300 eggs resulted in a decrease from 29 to 14 in the hosts parasitised per female, a decrease in the proportion of female progeny from 72 to 39%, a decrease in the female progeny per female from 18 to 4,8, and an increase in the proportion of runts from 2,4 to 12,4%. It is suggested that in mass culture ofTrichogramma unduly high parasite densities should be avoided in order to reduce the effect of mutual interference and raise the output of female progeny.     

Effect of temperature and host species on parasitism,development time and sex ratio of the egg parasitoid Trichogrammatoidea lutea Girault (Hymenoptera: Trichogrammatidae)

The developmental biology of Trichogrammatoidea lutea Girault (Hymenoptera: Trichogrammatidae) was studied at six constant temperatures (18, 21, 24, 27, 30 and 35 °C) on eggs of three lepidopteran host species: Helicoverpa armigera (Hübner) (Noctuidae), Chilo partellus (Swinhoe) (Crambidae) and Cadra cautella (Walker) (Pyralidae). T. lutea did not complete development at 35 °C on any of the three host species. Parasitism levels were highest on H. armigera at 27 °C (58%), C. cautella at 27 and 30 °C (31% and 28%) and C. partellus between 24 and 30 °C (13–17%). Realized progeny of T. lutea per parasitized host egg was influenced by host size. The number of progeny of T. lutea per parasitized host egg was highest on H. armigera, followed by C. partellus and lowest on C. cautella. The sex ratio was female biased on C. partellus, female biased on C. cautella with the exception of 21 °C and close to 1:1 on H. armigera. The rate of development from egg to pupa and egg to adult was fastest on H. armigera and slowest on C. partellus. Lower thresholds for development and degree days (DD) of T. lutea from egg to adult were 12.8 °C and 105.4 DD on H. armigera, 11.3 °C and 141.6 DD on C. partellus and 12.9 °C and 118.2 DD on C. cautella, respectively. Based on these results, H. armigera is the most suitable host for mass rearing of T. lutea for biological control of Lepidoptera pests because of the relatively high parasitism levels, short development time, greater clutch size and balanced sex ratio. C. cautella may also be used although longer exposure times might be required due to lower parasitism levels.     

Residues 240–250 in the C-Terminus of the Pirh2 Protein Complement the Function of the RING Domain in Self-Ubiquitination of the Pirh2 Protein

Pirh2 is a p53 inducible gene that encodes a RING-H2 domain and is proposed to be a main regulator of p53 protein, thus fine tuning the DNA damage response. Pirh2 interacts physically with p53 and promotes its MDM2-independent ubiquitination and subsequent degradation as well as participates in an auto-regulatory feedback loop that controls p53 function. Pirh2 also self-ubiquitinates. Interestingly, Pirh2 is overexpressed in a wide range of human tumors. In this study, we investigated the domains and residues essential for Pirh2 self-ubiquitination. Deletions were made in each of the three major domains of Pirh2: the N-terminal domain (NTD), Ring domain (RING), and C-terminal domain (CTD). The effects of these deletions on Pirh2 self-ubiquitination were then assessed using in vitro ubiquitination assays. Our results demonstrate that the RING domain is essential, but not sufficient, for Pirh2 self-ubiquitination and that residues 240–250 of the C-terminal domain are also essential. Our results demonstrate that Pirh2 mediated p53 polyubiquitination occurs mainly through the K48 residue of ubiquitin in vitro. Our data further our understanding of the mechanism of Pirh2 self-ubiquitination and may help identify valuable therapeutic targets that play roles in reducing the effects of the overexpression of Pirh2, thus maximizing p53''s response to DNA damage.     

Luteolin protects against lead acetate-induced nephrotoxicity through antioxidant,anti-inflammatory,anti-apoptotic,and Nrf2/HO-1 signaling pathways

Molecular Biology Reports - Lead (Pb) is one of the most common heavy metal pollutants affecting living organisms. It induces nephrotoxicity with significant alterations in renal structure and...     

Evaluation of the Possible Epileptogenic Activity of Ciprofloxacin: The Role of Nigella sativa on Amino Acids Neurotransmitters

The neuroprotective effect of Nigella sativa (NS) on amino acid neurotransmitters alteration in pentylenetetrazole (PTZ) and ciprofloxacin (CFX) treated rats in different brain regions was examined. The oral administration of NS induced an elevation in aspartate and glutamate contents, whereas the levels of GABA and glycine were decreased. Furthermore, the treated groups with PTZ and CFX caused a decrease in aspartate, glutamate and total antioxidant capacity levels, while the concentrations of GABA and glycine were increased after 14 days. Moreover, the pre- and post-treatment with NS in PTZ and CFX treated rats return the levels of these parameters near control values. So, it could be concluded that the treatment with CFX induced imbalance between the excitatory and the inhibitory amino acids which may lead to the initiation of epileptic seizures and the treatment with NS was found to ameliorate these neurological defects which reflect its potent antiepileptic activity.     

Alleviation of autophagy by knockdown of Beclin-1 enhances susceptibility of hippocampal neurons to proapoptotic signals induced by amino acid starvation

Autophagy has been described as a cellular response to stressful stimuli like starvation. One of its primary functions is to recycle amino acids from degraded proteins for cellular survival under nutrient deprived conditions. Autophagy is characterized by double membrane cytosolic vesicles called autophagosomes and prolonged autophagy is known to result in autophagic (Type II) cell death. Beclin-1 is involved in the regulation of autophagy in mammalian cells. This study examined the potential impact of knockdown of Beclin-1 in an autophagic response in HT22 neurons challenged with amino acid starvation (AAS). AAS exposure induced light chain-3 (LC-3)-immunopositive and monodansylcadaverine (MDC) fluorescent dye-labeled autophagosome formation in cell bodies as early as 3 h post-AAS in wild type cells. Elevated levels of the autophagosome-targeting LC3-II were also observed following AAS. In addition, neuronal death induced by AAS in HT22-cells led to a moderate activation of caspase-3, a slight upregulation of AIF and did not alter the HtrA2 levels. Autophagy inhibition by a knockdown of Beclin-1 significantly reduced AAS-induced LC3-II increase, reduced accumulation of autophagosomes, and potentiated AAS-mediated neuronal death. Collectively, this study shows that the both apoptotic and autophagic machineries are inducible in cultured hippocampal HT22 neurons subjected to AAS. Our data further show that attenuation of autophagy by a knockdown of Beclin-1 enhanced neurons susceptibility to proapoptotic signals induced by AAS and underlines that autophagy is per se a protective than a deleterious mechanism.