NF-kappaB-mediated modulation of inducible nitric oxide synthase activity controls induction of the Epstein-Barr virus productive cycle by transforming growth factor beta 1

Transforming growth factor beta 1 (TGF-β1) signal transduction has been implicated in many second-messenger pathways, including the NF-κB pathway. We provide evidence of a novel TGF-β1-mediated pathway that leads to extracellular signal-regulated kinase (ERK) 1/2 phosphorylation, which in turn induces expression of an Epstein-Barr virus (EBV) protein, ZEBRA, that is responsible for the induction of the viral lytic cycle. This pathway includes two unexpected steps, both of which are required to control ERK 1/2 phosphorylation: first, a quick and transient activation of NF-κB, and second, downregulation of inducible nitric oxide synthase (iNOS) activity that requires the participation of NF-κB activity. Although necessary, NF-κB alone is not sufficient to produce downregulation of iNOS, suggesting that another uncharacterized event(s) is involved in this pathway. Dissection of the steps involved in the switch from the EBV latent cycle to the lytic cycle will be important to understand how virus-host relationships modulate the innate immune system.     

Ultrastructure of the spermatozoon of Parachristianella trygonis Dollfus, 1946 (Trypanorhyncha: Eutetrarhynchidae)

The ultrastructural organization of the mature spermatozoon of the trypanorhynch cestode Parachristianella trygonis is described by transmission electron microscopy. The spermatozoon is a long and filiform cell, tapered at both ends, lacking both mitochondrion and crested bodies. Its cytoplasm contains 2 axonemes of the 9+'1' pattern of the Trepaxonemata longitudinally displaced, parallel cortical microtubules, the nucleus and glycogen in form of both alpha-glycogen rosettes and beta-glycogen particles. The anterior extremity of the spermatozoon is characterized by the presence of an arclike row of up to 10 parallel cortical microtubules that partially surround the first axoneme. The present study emphasizes the ultrastructural similarity between mature spermatozoa of all 4 trypanorhynchs that have been studied to date. Nevertheless, several features, i.e., the characteristics of spermatozoa extremities, the absence of crested bodies, and the possible presence of an arclike layer of cortical microtubules, need a more thorough analysis or confirmation in some of these species.     

Ultrastructural characters of the spermatozoon of the digenean Hypocreadium caputvadum Kacem et al., 2011 (Lepocreadioidea: Lepocreadiidae), an intestinal parasite of Balistes capriscus in Tunisia

The ultrastructural organization of the spermatozoon of the digenean Hypocreadium caputvadum (Lepocreadioidea: Lepocreadiidae) is described. Live digeneans were collected from Balistes capriscus (Teleostei: Balistidae) from the Gulf of Gabès, Tunisia (Eastern Mediterranean Sea). The mature spermatozoon of H. caputvadum shows several ultrastructural characters such as two axonemes of different lengths exhibiting the classical 9 + “1” trepaxonematan pattern, a nucleus, two mitochondria, granules of glycogen, external ornamentation of the plasma membrane and two bundles of parallel cortical microtubules. Moreover, in the anterior extremity, the second axoneme is partly surrounded by a discontinuous and submembranous layer of electron-dense material. Our study provides new data on the spermatozoon of H. caputvadum in order to improve the understanding of phylogenetic relationships in the Digenea, particularly in the superfamily Lepocreadioidea. In this context, the electron-dense material surrounding one of the axonemes in the anterior spermatozoon extremity constitutes the unique distinguishing ultrastructural character of lepocreadioideans, and it is present in spermatozoa of lepocreadiids, aephnidiogenids and gyliauchenids.     

<Emphasis Type="Italic">Pseudodiplectanum syrticum</Emphasis> n. sp. (Monogenea: Diplectanidae), a parasite of <Emphasis Type="Italic">Synapturichthys kleinii</Emphasis> (Teleostei: Soleidae) from off Tunisia

Pseudodiplectanum syrticum n. sp. (Monogenea: Diplectanidae) is described from the gills of Synapturichthys kleinii (Risso) collected from the Gulf of Gabès in the Mediterranean Sea off Tunisia. The new species differs from the congeneric species by the morphology of the penis and vagina. It resembles the Mediterranean species P. kearni Vala, Lopez-Roman & Boudaoud, 1980 from Solea vulgaris Quensel and P. gibsoni Oliver, 1987 from Michrochirus variegatus (Donovan) in its tubular penis, but it differs from these two species by having a vagina with a long tube presenting two loops and a male copulatory organ ending in a curved point. It also differs in the morphology and size of the transverse bars of the haptor. In P. syrticum the ventral transverse bar and dorso-lateral bars are longer than those of P. gibsoni (114 vs 69.5-89 microm and 48 vs 33-44 microm, respectively).