Density and maturation of rodlet cells in brain tissue of fathead minnows (Pimephales promelas) exposed to trematode cercariae

Evidence for the presumed linkage between the enigmatic rodlet cells of fish and exposure to helminths is anecdotal and indirect. We evaluated the proliferation and development of rodlet cells in the optic lobes of fathead minnows exposed to cercariae of Ornithodiplostomum ptychocheilus. Mean rodlet cell densities (ca. 10/mm²) in the optic lobes were similar between unexposed controls and minnows with 1- and 2-week old infections. Rodlet cell densities increased at 4 weeks p.i., reaching maxima (ca. 200/mm²) at 6 weeks p.i., followed by a decline at 9 weeks. This temporal pattern of proliferation and maturation paralleled the development of metacercariae within the optic lobes. Unencysted metacercariae develop rapidly within tissues of the optic lobes for approximately 4 weeks after penetration by cercariae, then shift to the adjacent meninges to encyst. The former stage is associated with tissue damage, the latter with massive inflammation of the meninges. Thus, peak densities and maturation of rodlet cells correspond to the period when inflammation of the meninges caused by the large metacercarial cysts is at a maximum. Our results support recent contentions that rodlet cells comprise part of the host inflammatory defence response.     

Mechanism of mda-5 Inhibition by Paramyxovirus V Proteins

The RNA helicases encoded by melanoma differentiation-associated gene 5 (mda-5) and retinoic acid-inducible gene I (RIG-I) detect foreign cytoplasmic RNA molecules generated during the course of a virus infection, and their activation leads to induction of type I interferon synthesis. Paramyxoviruses limit the amount of interferon produced by infected cells through the action of their V protein, which binds to and inhibits mda-5. Here we show that activation of both mda-5 and RIG-I by double-stranded RNA (dsRNA) leads to the formation of homo-oligomers through self-association of the helicase domains. We identify a region within the helicase domain of mda-5 that is targeted by all paramyxovirus V proteins and demonstrate that they inhibit activation of mda-5 by blocking dsRNA binding and consequent self-association. In addition to this commonly targeted domain, some paramyxovirus V proteins target additional regions of mda-5. In contrast, V proteins cannot bind to RIG-I and consequently have no effect on the ability of RIG-I to bind dsRNA or to form oligomers.     

Antigen-binding activity,structural characteristics and use of monoclonal antibodies to human alpha-1-microglobulin

Four monoclonal antibodies (mAbs), G6, F9, H8, and B2, against human alpha-1-microglobulin (A1M) have been produced and characterized. The parameters of affinity (K_p ～ 10⁹ M^?1), epitope specificity (the additively binding G6/F9, G6/H8, G6/B2, F9/H8, and F9/B2 pairs), and the observed effect of reversibility of structural changes induced by chemical agents allow use of these mAbs in biospecific methods of A1M purification and quantitative determination. The application of mAbs to an A1M enzyme immunoassay (analytical sensitivity—0.5 μg/l) and one step isolation of pure A1M by immunoaffinity chromatography was described.     

Density gradient analysis of newly replicated DNA from synchronized mouse lymphoma cells

The replication of DNA in synchronous cultures of mouse lymphoma cells was investigated by use of CsCl density gradient centrifugation. We found that the buoyant density of newly replicated DNA depended upon the particular stage of S phase in which synthesis occurred. In early S phase, newly replicated DNA exhibited buoyant densities which were slightly higher, on the average, than that of pre-existing DNA. As S phase progressed, newly replicated DNA shifted to lower buoyant densities, until, near the end of S phase, densities less than pre-existing DNA were observed. These observations are discussed in terms of their possible relevance to base compositional differences between nucleotide sequences made in early as opposed to middle or late S phase.