The Mechanism of the Calorigenic Action of Thyroid Hormone : Stimulation of Na+ + K+-activated adenosinetriphosphatase activity

In an earlier study, we proposed that thyroid hormone stimulation of energy utilization by the Na⁺ pump mediates the calorigenic response. In this study, the effects of triiodothyronine (T₃) on total oxygen consumption (Q_OO2), the ouabain-sensitive oxygen consumption [Q_OO2(t)], and NaK-ATPase in liver, kidney, and cerebrum were measured. In liver, ~90% of the increase in Q_OO2 produced by T₃ in either thyroidectomized or euthyroid rats was attributable to the increase in Q_OO2(t). In kidney, the increase in Q_OO2(t) accounted for 29% of the increase in Q_OO2 in thyroidectomized and 46% of the increase in Q_OO2 in euthyroid rats. There was no demonstrable effect of T₃ in euthyroid rats on Q_OO2 or Q_OO2(t) of cerebral slices. The effects of T₃ on NaK-ATPase activity in homogenates were as follows: In liver +81% from euthyroid rats and +54% from hypothyroid rats. In kidney, +21% from euthyroid rats and +69% from hypothyroid rats. T₃ in euthyroid rats produced no significant changes in NaK-ATPase or Mg-ATPase activity of cerebral homogenates. Liver plasma membrane fractions showed a 69% increase in NaK-ATPase and no significant changes in either Mg-ATPase or 5'-nucleotidase activities after T₃ injection. These results indicate that thyroid hormones stimulate NaK-ATPase activity differentially. This effect may account, at least in part, for the calorigenic effects of these hormones.     

Comparing the frequency of CD33+ pSTAT3+ myeloid-derived suppressor cells and IL-17+ lymphocytes in patients with prostate cancer and benign prostatic hyperplasia

Prostate cancer (PCa) is one of the most epidemic types of cancer in men. The tumor microenvironment (TME) of PCa is involved in the emergence of immunosuppressive factors such as myeloid-derived suppressor cells (MDSC), which regulate the immune system by several mechanisms, including interleukin (IL)-10 production. On the other hand, IL-17⁺ helper T cells (Th17) induce MDSCs and chronic inflammation in TME by producing IL-17. This study demonstrated that the frequency of CD33⁺ pSTAT3⁺ MDSC and IL-17⁺ lymphocyte as well as IL-10 messenger RNA (mRNA) expression were significantly higher in the PCa patients than in the benign prostatic hyperplasia (BPH) group. Moreover, there was no significant relationship between the frequency of CD33⁺ pSTAT3⁺ MDSC, and IL-17⁺ lymphocyte with Gleason scores in the PCa group. We suggested that the higher frequency of CD33⁺ pSTAT3⁺ MDSC and IL-17⁺ lymphocyte and the more frequent expression of IL-10 mRNA in PCa patients may play roles in tumor progression from BPH to PCa.     

Tissue slice cultures from humans or rodents: a new tool to evaluate biological effects of heavy ions

The aim of this interdisciplinary project is to establish slice culture preparations from rodents and humans as a new model system for studying effects of X-rays and heavy ions within normal and tumor tissues. The advantage of such slice cultures relies on the conservation of an organotypic environment, the easy treatment and observation by live-imaging microscopy, and the independence from genetic immortalization strategies used to generate cell lines. Rat brains as well as human tumors were cut into 300-μm-thick sections and cultivated in an incubator in a humidified atmosphere at 37°C. This is realized by a membrane-based culture system with a liquid–air interface. With this system, it is possible to keep rodent slices viable for several months. Human brain tumor slices remained vital for at least 21 days. Slices were irradiated with X-rays at the radiation facility of the University Hospital in Frankfurt/Main at doses up to 40 Gy. Heavy ion irradiations were performed at GSI (Darmstadt) with different ions, energies, and doses. The irradiated slices were analyzed by 3D-confocal microscopy following immunostaining for DNA damage, microglia, and proliferation markers. The phosphorylated histone γH2AX proved to be suitable for the detection of ion traversals in this system.     

Host discrimination by the endoparasitoid Psyllaephagus pistaciae (Hymenoptera: Encyrtidae): A case of time-dependent ability

Host-discrimination behavior by the koinobiont parasitoid, Psyllaephagus pistaciae Ferrière (Hymenoptera: Encyrtidae), the major biocontrol agent of the common pistachio psylla, Agonoscena pistaciae Burckhardt & Lauterer (Hemiptera: Psyllidae), in Iran, was investigated in the laboratory. The results demonstrated that P. pistaciae quickly detected and avoided freshly parasitized hosts, either after antennating or by probing with their ovipositor. However, this discriminatory ability declined with time, probably influenced by both external and internal markers left by the previous ovipositing female. The results also confirmed that female P. pistaciae responded to changes in host quality associated with the parasitoid's larval development 4 days after the initial parasitization, clearly indicating that the second female could detect the presence of the larvae and adjust her host-selection decision. In addition, psyllid nymphs treated topically with a solution of Dufour's gland were rejected by the parasitoid, showing that Dufour's gland secretion had a significant effect as a host marking chemical. The current study also showed that superparasitism increased the host-mortality and that the rate of encapsulation decreased, suggesting that, when two eggs are laid in the same psyllid nymph, only one parasitoid develops to an adult.     

Differential accumulation of Glut1 in the non-DRM domain of the plasma membrane in response to the inhibition of oxidative phosphorylation

Approximately 50% of Glut1 in the plasma membrane of Clone 9 cells is localized to the detergent-resistant membrane (DRM) fraction. Acute exposure (90 min) to 5mM azide stimulated glucose transport by approximately 4.7-fold and increased the abundance of Glut1 in the non-DRM fraction of the plasma membrane by approximately 2.9-fold while the abundance of Glut1 in the DRMs was not changed. In parallel experiments, approximately 17 h exposure to azide further increased the rate of glucose transport over that observed at 90 min by approximately 33% and increased plasma membrane Glut1 content by approximately 3.5-fold over control. The increase in total plasma membrane Glut1 reflected a approximately 4.7-fold increase of Glut1 content in the non-DRM fraction and a approximately 2.6-fold increase in the DRMs. We conclude that acute exposure to azide increases Glut1 content in the non-DRM fractions, while prolonged exposure to azide increases the Glut1 content in both non-DRM and DRM fractions. These changes may play an important role in the stimulation of glucose transport in response to the inhibition of oxidative phosphorylation.     

Parasitoids associated with the common pistachio psylla, Agonoscena pistaciae, in Iran

The parasitoids associated with the common pistachio psylla, Agonoscena pistaciae Burckhardt and Lauterer, were investigated at three pistachio plantations in Rafsanjan, Iran. Of the 6504 wasps emerging from mummified psyllids, 46% were the primary parasitoid Psyllaephagus pistaciae Ferrière, and the remaining 54% represented six species of hymenopterous hyperparasitoids, including Chartocerus kurdjumovi (Nikol’skaja), Marietta picta (André), Pachyneuron aphidis (Bouché), Pachyneuron muscarum (Linnaeus), Psyllaphycus diaphorinae (Hayat), and Syrphophagus aphidivorus (Mayr). Lysiphlebus fabarum Marshall, the parasitoid of Aphis gossypii Glover and Aphis craccivora Koch present on weeds, was found to be an alternative host for three major hyperparasitoids of A. pistaciae. The most abundant hyperparasitoid was S. aphidivorus, appearing during the growing season in all trial locations on psyllids and aphids in pistachio orchards. The weed-infesting aphids, along with their primary parasitoid, can act as a reservoir of A. pistaciae secondary parasitoids. Therefore, parasitized aphids allow populations of secondary parasitoids to increase and consequently to apply higher pressure on P. pistaciae. We detected that two primary parasitoid species, including P. pistaciae and L. fabarum, attacking different species of hosts interact indirectly through shared secondary parasitism. It is suggested that the community structure of A. pistaciae may be influenced by apparent competition, although more work is needed to provide firm evidence.     

Effect of thyroid hormone on the distribution and activity of Na, K-ATPase in ventricular myocardium

Employing detergent-free sucrose-density gradient fractionation method we isolated cholesterol-rich lighter membrane fractions containing ∼10% of protein, ∼30% of cholesterol in membranes of ventricular myocardium. Cholesterol-rich lighter membrane fractions contain >70% of Na, K-ATPase and caveolins 1 and 3 and <10% of β-actin. Treatment of hypothyroid rats with T₃ increased the relative abundance of both α1 and β1 Na, K-ATPase subunits in total membranes by 4- to 5-fold (with no change in caveolin-3), and resulted in 1.9-fold increase in enzyme activity. T₃-induced Na, K-ATPase subunits were preferentially distributed to the lighter fractions (#s 4, 5 and 6); and increased abundance of α1 and β1 were 34-70% and 43-68%, respectively. We conclude that the activity of Na, K-ATPase is not uniform in cardiac membranes, and while a significant amount of Na, K-ATPase is present in cardiac cholesterol-rich membrane fractions, the intrinsic activity is significantly less than the enzyme present in relatively cholesterol-poor membranes.     

Enhanced resistance to two stem borers in an aromatic rice containing a synthetic cryIA(b) gene

Rice cultivars of isozyme group V include high-quality, aromatic rices that are difficult to improve by traditional methods because of the loss of quality characters upon sexual hybridization. Their low-tillering plant type predisposes them to economic loss from attack by stem borers, a group of insects to which they are susceptible. We report here the enhancement of stem borer resistance in cv. Tarom Molaii through transformation by microprojectile bombardment. Embryogenic calli derived from mature seeds were bombarded with gold particles coated with plasmid pCIB4421, carrying a synthetic truncated toxin gene based on the cryIA(b) gene from Bacillus thuringiensis, and plasmid pHygII, carrying the hygromycin phosphotransferase (hpt) selectable marker gene. Inclusion of 50 mg/l hygromycin B in culture media from bombardment through to rooting of plantlets eliminated escapes. The procedure generated three independent hpt transformants of which two also contained the cryIA(b) gene. One such line (No. 827) produced truncated (67 kDa) CryIA(b) protein equivalent to about 0.1% of total soluble protein. The cryIA(b) gene was controlled by the promoter of the maize C₄ PEP carboxylase gene and was expressed in leaf blades but was not expressed to a detectable level in dehulled mature grain. Line 827 contained about 3 copies of the cryIA(b) gene which segregated as a single dominant Mendelian locus in the second (T₁) and third (T₂) generations and co-segregated with enhanced resistance to first-instar larvae of striped stem borer (Chilo suppressalis) and yellow stem borer (Scirpophaga incertulas). T₂ line 827-6 homozygous for the cryIA(b) gene showed no dead hearts or whiteheads after infestation with stem borers, whereas T₂ line 827-25 lacking the gene averaged 7 dead hearts per plant and 2.25 whiteheads per plant. These results establish that transformation of high-quality rices of group V is a feasible alternative to sexual hybridization.