Tobacco mosaic virus (TMV) derivatives that encode movement protein (MP) as a fusion to the green fluorescent protein (MP:GFP) were used in combination with antibody staining to identify host cell components to which MP and replicase accumulate in cells of infected Nicotiana benthamiana leaves and in infected BY-2 protoplasts. MP:GFP and replicase colocalized to the endoplasmic reticulum (ER; especially the cortical ER) and were present in large, irregularly shaped, ER-derived structures that may represent "viral factories." The ER-derived structures required an intact cytoskeleton, and microtubules appeared to redistribute MP:GFP from these sites during late stages of infection. In leaves, MP:GFP accumulated in plasmodesmata, whereas in protoplasts, the MP:GFP was targeted to distinct, punctate sites near the plasma membrane. Treating protoplasts with cytochalasin D and brefeldin A at the time of inoculation prevented the accumulation of MP:GFP at these sites. It is proposed that the punctate sites anchor the cortical ER to plasma membrane and are related to sites at which plasmodesmata form in walled cells. Hairlike structures containing MP:GFP appeared on the surface of some of the infected protoplasts and are reminiscent of similar structures induced by other plant viruses. We present a model that postulates the role of the ER and cytoskeleton in targeting the MP and viral ribonucleoprotein from sites of virus synthesis to the plasmodesmata through which infection is spread. INTRODUCTIONMost plant viruses encode one or more proteins that are required to achieve local and systemic invasion of the host. These so-called movement proteins (MPs) enable viruses to exploit plasmodesmata, the gated, plasma membrane-lined channels that provide symplastic continuity between adjacent cells and through which plant cells communicate (Epel, 1994;Lucas and Gilbertson, 1994; Fenczik et al., 1995).Pioneering studies of MP functions were performed with the MP of tobacco mosaic virus (TMV) (Deom et al., 1987;Meshi et al., 1987). In infected tobacco plants as well as in transgenic plants, the MP accumulates in plasmodesmata and increases their size exclusion limit (Tomenius et al., 1987;Wolf et al., 1989; Atkins et al., 1991a; Ding et al., 1992;Moore et al., 1992;Oparka et al., 1997). The protein also binds single-stranded nucleic acids in vitro, resulting in unfolded and elongated protein-nucleic acid complexes.This observation led to the hypothesis that the virus moves from cell to cell in the form of a viral ribonucleoprotein complex (vRNP) that in size and structure is compatible with the modified plasmodesmata (Citovsky et al., 1990(Citovsky et al., , 1992.Although it is evident that the MP and vRNP must enlist cytoplasmic structures to aid transfer from their site of synthesis to the plasmodesmata, little is known about the nature of these components and about the targeting mechanism per se. F-actin and microtubules were proposed as targeting systems for MP (Heinlein et al., 1995;McLean et al., 1995; Carrington et al....

Tobacco mosaic virus (TMV) derivatives that encode movement protein (MP) as a fusion to the green fluorescent protein (MP:GFP) were used in combination with antibody staining to identify host cell components to which MP and replicase accumulate in cells of infected Nicotiana benthamiana leaves and in infected BY-2 protoplasts. MP:GFP and replicase colocalized to the endoplasmic reticulum (ER; especially the cortical ER) and were present in large, irregularly shaped, ER-derived structures that may represent "viral factories." The ER-derived structures required an intact cytoskeleton, and microtubules appeared to redistribute MP:GFP from these sites during late stages of infection. In leaves, MP:GFP accumulated in plasmodesmata, whereas in protoplasts, the MP:GFP was targeted to distinct, punctate sites near the plasma membrane. Treating protoplasts with cytochalasin D and brefeldin A at the time of inoculation prevented the accumulation of MP:GFP at these sites. It is proposed that the punctate sites anchor the cortical ER to plasma membrane and are related to sites at which plasmodesmata form in walled cells. Hairlike structures containing MP:GFP appeared on the surface of some of the infected protoplasts and are reminiscent of similar structures induced by other plant viruses. We present a model that postulates the role of the ER and cytoskeleton in targeting the MP and viral ribonucleoprotein from sites of virus synthesis to the plasmodesmata through which infection is spread.

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Background Muscletech Hydroxycut® (Iovate Health Sciences Research, Oakville, Ontario) was a popular weight loss supplement that was recalled by the manufacturer in May 2009 based on reports of hepatotoxicity associated with this supplement. Objective To characterize the clinical presentation of Hydroxycut®-associated liver injury and to adjudicate these cases for causal association with Hydroxycut®. Design Case series. Setting Academic tertiary care hospitals and FDA databases. Measurements Assessment of causality and grading of severity of liver injury using methodology developed by the Drug-Induced Liver Injury Network (DILIN) study. Results Eight patients who developed liver injury after taking Hydroxycut treated at different medical centers were identified. All were hospitalized and 3 of 8 patients required liver transplantation. Nine other cases with adequate clinical information were obtained from the FDA MedWatch database including one fatal case of acute liver failure. Usual symptoms were jaundice, fatigue, nausea, vomiting and abdominal pain. Most patients exhibited a hepatocellular pattern of injury. Adjudication for causality revealed 8 cases as definite, 5 highly likely, 2 probable and 2 were considered as possible. Conclusions Hydroxycut® has been clearly implicated as a cause for severe liver injury that may lead to acute liver failure and death. Weight loss supplements represent a class of dietary supplements that should be regarded as capable of causing severe hepatic toxicity when the usual causes of identified liver injury cannot be otherwise elucidated.

The German economy has been widely seen as failing to develop the commercial innovation competencies necessary to compete in new technologies. Starting in the mid-1990s, the German government instituted a series of new technology policies designed to orchestrate the development of small entrepreneurial technology firms. These policies have fostered several hundred new high-technology start-ups in Germany. This development represents an interesting challenge to prevailing institutional theory, which tends to view the characteristics of organizations as strongly constrained by the orientation of a number of key national institutional frameworks. Focusing on biotechnology, this article examines the relative importance of national institutional frameworks as opposed to sector-specific policies that are presently pervasive in Germany. Analysis of the new firms demonstrates that Germany's new technology policies have facilitated important extensions within the business system that have, for the first time, allowed the systematic promotion of entrepreneurial technology companies. However, the dominant strategies of market specialization and company organizational patterns found within these companies have been strongly influenced by incentives and constraints created by long-established national institutional structures. Technology policy has, however, promoted institutional adaptiveness by providing opportunities for firms to experiment with or reconfigure elements of relatively stable national institutional frameworks to create new business practices.

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The paper explores the influence of institutional frameworks on the evolution of the German software and biotechnology sectors. It links institutional constraints to poor performance of German firms in high volume market niches characterized by turbulent technological change and substantial financial risk. However, German firms are prospering in software services and “platform technologies” in biotechnology. The company organizational structures and investment strategies needed to excel in these market segments provide a close “fit” with incentives created within the German economy.

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