Permethrin- and malathion-induced macromolecular abnormalities in adult Tribolium castaneum (herbst)

In Tribolium castaneum adults, sublethal doses of 1 and 2 ppm permethrin and 300 ppm malathion led to significant changes in amylase, trehalase, acid phosphatase, alkaline phosphatase, aspartate aminotransferase, alanine aminotransferase, lactate dehydrogenase, and isocitrate dehydrogenase activities. Malathion at 150 ppm did not affect phosphatases and lactate dehydrogenase. Both malathion and permethrin significantly increased cholinesterase activity. Mixing of the two insecticides resulted in antagonistic action with reference to various enzymatic activities. Glucose and glycogen contents were at first mobilized for energy supply under insecticidal stress conditions followed by lipid and cholesterol. Soluble protein, total protein, free amino acids, and urea contents remained unaltered under all experimental conditions.     

Stimulation of Inositol 1,4,5-Trisphosphate (IP3) Receptor Subtypes by Adenophostin A and Its Analogues

Inositol 1,4,5-trisphosphate receptors (IP₃R) are intracellular Ca²⁺ channels. Most animal cells express mixtures of the three IP₃R subtypes encoded by vertebrate genomes. Adenophostin A (AdA) is the most potent naturally occurring agonist of IP₃R and it shares with IP₃ the essential features of all IP₃R agonists, namely structures equivalent to the 4,5-bisphosphate and 6-hydroxyl of IP₃. The two essential phosphate groups contribute to closure of the clam-like IP₃-binding core (IBC), and thereby IP₃R activation, by binding to each of its sides (the α- and β-domains). Regulation of the three subtypes of IP₃R by AdA and its analogues has not been examined in cells expressing defined homogenous populations of IP₃R. We measured Ca²⁺ release evoked by synthetic adenophostin A (AdA) and its analogues in permeabilized DT40 cells devoid of native IP₃R and stably expressing single subtypes of mammalian IP₃R. The determinants of high-affinity binding of AdA and its analogues were indistinguishable for each IP₃R subtype. The results are consistent with a cation-π interaction between the adenine of AdA and a conserved arginine within the IBC α-domain contributing to closure of the IBC. The two complementary contacts between AdA and the α-domain (cation-π interaction and 3″-phosphate) allow activation of IP₃R by an analogue of AdA (3″-dephospho-AdA) that lacks a phosphate group equivalent to the essential 5-phosphate of IP₃. These data provide the first structure-activity analyses of key AdA analogues using homogenous populations of all mammalian IP₃R subtypes. They demonstrate that differences in the Ca²⁺ signals evoked by AdA analogues are unlikely to be due to selective regulation of IP₃R subtypes.     

Cereal protoplast recalcitrance

Summary Cereal leaf protoplasts are extremely difficult to culture (recalcitrant) in vitro. There have been few reports of division and the protoplasts typically exhibit excessive enlargement and vacuolization with reduced cell wall deposition. Inasmuch as leaf base explants are capable of callus formation in vitro, protoplasts derived from this tissue must have lost the ability to divide as a consequence of changes induced by the wall-digestion process. We review evidence suggesting that the inhibition of mitosis in these protoplasts is a consequence of a cascade of events initiated at the plasma membrane. The enzyme treatment necessary for wall removal triggers membrane depolarization and other changes that can lead to the initiation of lipid peroxidation and oxidative stress. Mitotically inactive cereal leaf protoplasts are unable to mount a protective response to these degradative processes. Consequently, the resulting membrane perturbations and permeabilization give rise to secondary effects on the cytoskeleton and the cell wall. These effects include reduced or absent microtubules as well as reduced and uneven wall deposition. Such abnormalities are observed in cereal leaf protoplasts and are sufficient to account for recalcitrance because the occurrence of mitosis is strongly dependent on a normal cell wall and cytoskeleton. This paper is NRCC number 32475.     

A mathematical model with young predation

We generalise the model of [21] in which the author considered a predator-prey system with predators eating only the young ones (or eggs) of the prey species. The prime assumption of the present paper is that the birth rate (per unit individual per unit time) of predators depends not only on the current prey egg-level but also on all previous prey egg-levels. It is seen that under this assumption an otherwise stable system may be stable as well as unstable leading to the conclusion that young predation with time delay is less stable than without it. Finally for the model of [21] we prove a result which shows that large predation rates help in the co-existence of both predator and prey species.     

Phenolic compounds and antioxidants from Eucalyptus camaldulensis as affected by some extraction conditions,a preparative optimization for GC-MS analysis

Abstract

Four organic solvents along with water were applied for the conventional extraction of Eucalyptus camaldulensis (Myrtaceae), phenolic contents and antioxidant activities were investigated through variable protocols and correlation coefficients were considered, the phenolic composition was also characterized by Gas chromatography-mass spectrometry (GC-MS). Using solvents with dissimilar polarities affected the phenolic yields extracted from E. camaldulensis and their related antioxidant activities varied significantly among the four investigated plant organs. The leaf extract of acetone 70% contained the highest amount of phenolic compounds (46.56?mg/g dry weight); while the bud-water boiled extract maintained the maximum value of tannins (45.68?mg/g dry weight). Correlation coefficients indicated that phenolic compounds were mostly accountable for the phosphomolybednum antioxidant potentials (0.520), followed by tannins (0.460). Also, both the reducing power activities and hydrogen peroxide scavenging of E. camaldulensis extracts positively correlated with tannins, but at different significance degrees. However, the GC-MS analysis revealed that most of the detected phenolic constituents were more abundant in the plant seed. So, the existence of some other compounds such as organic acids, along with phenolics, may have increased the antioxidant potentials of leaf and bud. Undeniably, the optimization of extraction conditions could stimulate the antioxidant capabilities of the plant extracts of E. camaldulensis.     

Effectiveness of Antegrade Access in Bladder Tumors With Inaccessible Urethra

Inaccessible urethra with no retrograde endoscopic access due to multiple/diffuse strictures or multiple urethrocutaneous fistulas with acute urinary retention due to posturethral instrumentation (transurethral resection of bladder tumor [TURBT], or TURBT with transurethral resection of the prostate [TURP]), is a rare entity. Management of such a case with a bladder tumor for TURBT/surveillance cystoscopy poses a great challenge. The authors present 12 cases of bladder tumor with inaccessible urethra, 10 cases due to multiple strictures (post-TURBT and/or TURP), and 2 cases due to urethrocutaneous fistulas (post-TURBT), who presented to our emergency department with acute urinary retention. Emergent suprapubic catheterization was used as a temporary treatment method.Key words: Suprapubic cystostomy, Inaccessible urethra, Bladder tumors, Tract seedlingBladder tumors are the most common neoplasm of the lower urinary tract, comprising 6% of all malignancies in men and 2% of those in women.¹ A majority of patients present with gross painless hematuria, usually as the sole presenting symptom.² Bladder carcinoma is unique among human neoplasms in that many of its etiologic factors are known; the urologist should be aware of the possible occupational exposures to urothelial carcinogens.³ Initial symptoms of urothelial carcinoma of the bladder (UCB) include microhematuria, painless macrohematuria, and/or irritative voiding symptoms, and require further investigation. Carcinoma in situ of the bladder causes irritative lower urinary tract symptoms (LUTS) more often than does papillary UCB. Histopathologic evaluation is necessary to assess stage and grade with sufficient certainty after the appearance of bladder tumors.⁴ Bladder tumors spread by implantation in abdominal wounds, denuded epithelium, resected prostatic fossa, or traumatized urethra⁵; implantation occurs most often with high-grade tumors.