Ultrastructural and cytochemical aspects of the germarium and the vitellarium in Syndesmis patagonica (Platyhelminthes,Rhabdocoela, Umagillidae)

The cytoarchitecture of the female gonad of the endosymbiont umagillid Syndesmis patagonica has been investigated using electron microscopy and cytochemical techniques. The female gonad consists of paired germaria and vitellaria located behind the pharynx in the mid‐posterior region of the body. Both the germaria and the vitellaria are enveloped by an outer extracellular lamina and an inner sheath of accessory cells which contribute to the extracellular lamina. Oocyte maturation occurs completely during the prophase of the first meiotic division. Oocyte differentiation is characterized by the appearance of chromatoid bodies and the development of endoplasmic reticulum and Golgi complexes. These organelles appear to be involved in the production of round granules, about 2–2.5 μm in diameter, with a homogeneous electron‐dense core surrounded by a granular component and a translucent halo delimited by a membrane. These egg granules migrate to the periphery of mature oocytes, are positive to the cytochemical test for polyphenol detection, are unaffected by protease and have been interpreted as eggshell granules. The mature oocytes also contain a small number of yolk granules, lipid droplets, and glycogen particles scattered throughout the ooplasm. The vitellaria are branched organs composed of vitelline follicles with vitellocytes at different stages of maturation. Developing vitellocytes contain well‐developed rough endoplasmic reticulum and small Golgi complexes involved in the production of eggshell and yolk globules. Eggshell globules are round, measure 4–5 μm in diameter, and have a mosaic‐like patterned content which contains polyphenols. The yolk globules, 2–3 μm in diameter, show a homogeneous protein content of medium electron density, devoid of polyphenols, and completely digested by protease. The mature vitellocytes also contain glycogen as further reserve material. The presence of polyphenolic eggshell granules in the oocytes and of polyphenolic eggshell globules with a mosaic‐like pattern in the vitellocytes have been considered apomorphic features of the Rhabdocoela + Prolecithophora. J. Morphol. 275:703–719, 2014. © 2014 Wiley Periodicals, Inc.     

Leukocytes, oxygen radicals, and myocardial injury due to ischemia and reperfusion

Ischemic myocardium generates stimuli for neutrophil chemotaxis before the final extent of irreversible ischemic injury is attained. Reperfusion accelerates the infiltration of ischemic myocardium by neutrophils. Oxygen radicals released by the activated neutrophils may exacerbate the tissue damage caused by ischemia. Neutrophil depletion by antiserum was shown to limit infarct size in dogs undergoing coronary occlusion for 90 minutes followed by reperfusion for 6 or 72 hours, but not in dogs undergoing occlusion for 4 hours. Prostacyclin, which inhibits the generation of superoxide anions by neutrophils, also limited canine myocardial injury despite no effect on collateral blood flow. Iloprost, an analogue of prostacyclin that inhibits neutrophils also reduced infarct size, while SC39902, an analogue that does not inhibit neutrophils, did not alter infarct size. The results suggest that oxygen radicals released by activated neutrophils play a role in the pathophysiology of myocardial injury due to ischemia followed by reperfusion.     

Solid-phase de novo synthesis of a (±)-2-deoxy-glycoside

The solid-phase synthesis of methyl 2-deoxy-3-O-benzyl-d,l-arabino-hexopyranoside was achieved in a six-step sequence via a de novo strategy based on the hetero-Diels-Alder reaction of a vinyl ether supported on an azalactone-functionalized polystyrene resin, followed by the functional modification of the heteroadduct and the final release of the methyl glycoside by acidic solvolysis.     

Differential gene regulation by Epstein-Barr virus type 1 and type 2 EBNA2

A transfection assay with a lymphoblastoid cell line infected with Epstein-Barr virus was used to compare the abilities of type 1 and type 2 EBNA2 to sustain cell proliferation. The reduced proliferation in cells expressing type 2 EBNA2 correlated with loss of expression of some cell genes that are known to be targets of type 1 EBNA2. Microarray analysis of EBNA2 target genes identified a small number of genes that are more strongly induced by type 1 than by type 2 EBNA2, and one of these genes (CXCR7) was shown to be required for proliferation of lymphoblastoid cell lines. The Epstein-Barr virus LMP1 gene was also more strongly induced by type 1 EBNA2 than by type 2, but this effect was transient. Type 1 and type 2 EBNA2 were equally effective at arresting cell proliferation of Burkitt's lymphoma cell lines lacking Epstein-Barr virus and were also shown to cause apoptosis in these cells. The results indicate that differential gene regulation by Epstein-Barr virus type 1 and type 2 EBNA2 may be the basis for the much weaker B-cell transformation activity of type 2 Epstein-Barr virus strains compared to type 1 strains.     

Postnatal changes in Na,K-ATPase isoform expression in rat cardiac ventricle. Conservation of biphasic ouabain affinity.

The cardiac glycoside sensitivity of the rat heart changes during postnatal maturation and in response to certain pathological conditions. The Na,K-ATPase is thought to be the receptor for cardiac glycosides, and there are three isozymes of its catalytic (alpha) subunit with different cardiac glycoside affinities: alpha 1 (low affinity) and alpha 2 and alpha 3 (high affinity). We examined the developmental expression of the alpha subunit isozymes in rat ventricular membrane preparations by immunoblotting with isozyme-specific antibodies. The alpha 1 isozyme was present throughout all stages of maturation. A developmental switch from alpha 3 to alpha 2 occurred between 14 and 21 days after birth. Measurements of [3H]ouabain binding and inhibition of Na,K-ATPase activity indicated that alpha 2 and alpha 3 should make equivalent contributions to ion pump capacity; in both neonatal natal and adult preparations, ouabain interacted with a single class of high-affinity binding sites (KD = 15 or 40 nM, respectively; Bmax = 4-5 pmol/mg protein), and at low concentrations produced a similar degree of Na,K-ATPase inhibition (25%). The results indicate that the developmental difference in cardiac glycoside sensitivity cannot be explained by quantitative differences in the proportion of high-affinity isozymes of the Na,K-ATPase. The switch from alpha 3 to alpha 2 coincides with other major changes in cardiac electrophysiology and calcium metabolism.