Evidence of novel type of ribosome in eukaryotic intermediate flatworm

In all organisms, messenger-directed protein synthesis is catalyzed by ribonucleoprotein particles called ribosomes. A ribosome is typically composed of one small and one large subunit which contain one short (18S) and one long (28S) rRNAs, respectively. Surprisingly, in this study, three similar size rRNAs (18-21S) were revealed in the electrophoresis profile of the total RNAs of tapeworm _Spirometra erinaceiuropaei_. Northern blot analysis shows that one of the three bands belongs to 18S rRNA, and the other two bands are of 28S rRNAs, implying structurally distinct ribosomes in this intermediate animal. Furthermore, similar, but not identical profiles were observed in two other tapeworms _Diphyllobothrium hottai_ and _Diphyllobothrium Nipponkaiizeme_. Relevant to this finding, in flatworm _Paragonimus westermani_, 18S rRNAs were found much more numerous than 28S rRNAs. Moreover, consistent with this biochemical finding, transmission electron microscopy examinations show that the ribosomes isolated from _Spirometra erinaceiuropaei_ are composed of either one ball or two similar size subunits (balls), while the structure of ribosomes isolated from control liver tissue exactly match the conventional large and small subunit ribosome model. Our study provides direct biochemical and biophysical evidence of structurally distinct novel type of ribosomes in intermediate eukaryotic flatworms. These finding may be important for re-recognition of biological protein synthesis and evolutionary process of living things

Regulation of TNF-α, IL-1β and ICAM-1 Gene Expression in THP-1 Monocytes Stimulated with Plasmodium falciparum-Cultured Medium by Excretory/Secretory Products from Spirometra erinaceieuropaei Plerocercoids

We have reported that excretory/secretory (ES) products from Spirometra erinaceieuropaei plerocercoids suppress production and gene expression of tumor necrosis factor (TNF)-α in murine macrophages stimulated with lipopolysaccharide. The present study demonstrates that ES products suppress TNF-α, interleukin (IL)-1β and intercellular adhesion molecule (ICAM)-1 gene expression in human monocytic leukemia cell line THP-1 stimulated with Plasmodium falciparum-cultured medium (Pf-CM). Inhibition of extracellular-signal regulated protein kinase 1/2 (ERK1/2) with PD98059 reduced TNF-α, IL-1β and ICAM-1 gene expression; on the contrary inhibition of p38 mitogen-activated protein kinase (MAPK) with SB203580 increased the expression of these genes. These findings indicated that ERK1/2, but not p38 MAPK pathway is important for induction of TNF-α, IL-1β and ICAM-1 gene expression in Pf-CM stimulated THP-1 monocytes. ES products additionally suppress IL-1β, but not TNF-α and ICAM-1 gene expression in Pf-CM stimulated THP-1 cells treated with PD98059. We hypothesize that ES products may be useful in reducing falciparum malaria-induced inflammatory response and sequestration in the late stage of malarial diseases such as cerebral malaria

Suppression of LPS-induced Cyclooxygenase-2 (cox-2) Gene Expression in Mouse Macrophages by Excretory/Secretory Products of Spirometra erinaceieuropaei Plerocercoids

The escape mechanism of parasites from inflammatory processes has been thought to be one of the most important tools for their survival in infected tissues. On the other hand, inducible cyclooxygenase-2 (cox-2) has been shown to play a major role in the process of inflammation. We investigated the effect of excretory/secretory (ES) products from the plerocercoids of Spirometra erinaceieuropaei on cox-2 gene expression in a murine macrophage cell line (RAW 264.7). Preincubation of the macrophages with the ES products inhibited LPS-induced cox-2 mRNA expression by 75% as well as its protein production. Dibutyryl cAMP enhances LPS-induced cox-2 mRNA expression. The ES products also inhibited this enhanced expression by 46%. Inhibition of p38 mitogen-activated protein kinase (MAPK) with SB203580 or that of extracellular signal-regulated protein kinase with PD98059 reduced LPS-induced cox-2 mRNA expression by 75% or 52%, respectively, along with its protein production. This evidence suggests that both MAPK pathways are crucial for full induction of cox-2 gene expression. One experiment using a transcriptional inhibitor, actinomycin-D, showed that the ES products destabilized LPS-induced cox-2 mRNA in RAW 264.7 macrophages. These results show that ES products from the plerocercoids of Spirometra erinaceieuropaei suppress LPS-induced cox-2 mRNA expression in murine RAW 264.7 macrophages, and may attenuate inflammation around the plerocercoids of S. erinaceieuropaei

Human pulmonary dirofilariasis presenting as a small nodule with a cavity

A 73-year-old woman had a 4-year history of lung fibrosis from collagen vascular disease. She presented with a complaint of dry cough. A chest radiograph showed a 2-cm solitary pulmonary nodule with a small cavity in the right lower lobe. Preoperatively, we performed computed tomography of the chest and measured tumor markers. Video-assisted thoracotomy was performed because we could not rule out lung cancer. Pathologic analysis confirmed the presence of a granuloma with Dirofilaria immitis. In Japan, the incidence of human dirofilariasis has steadily increased and must be considered in the workup of cavitary pulmonary nodules

Evidence of existence of totally different types of ribosomes in intermediate animals

In all organisms, messenger-directed protein synthesis is catalyzed by ribonucleoprotein particles called ribosomes. A ribosome is typically composed of one small and one large subunit which contain one short (18S) and one long (28S) rRNAs, respectively. Surprisingly, in this study, three similar size rRNAs (18-21S) were revealed in the electrophoresis profile of the total RNAs of tapeworm _Spirometra erinaceiuropaei_. Northern blot analysis shows that one of the three bands belongs to 18S rRNA, and the other two bands are of 28S rRNAs, implying structurally distinct ribosomes in this intermediate animal. Furthermore, similar, but not identical profiles were observed in two other tapeworms _Diphyllobothrium hottai_ and _Diphyllobothrium Nipponkaiizeme_. Relevant to this finding, in flatworm _Paragonimus westermani_, 18S rRNAs were found much more numerous than 28S rRNAs. Moreover, consistent with this biochemical finding, transmission electron microscopy examinations show that the ribosomes isolated from _Spirometra erinaceiuropaei_ are composed of either one ball or two similar size subunits (balls), while the structure of ribosomes isolated from control liver tissue exactly match the conventional large and small subunit ribosome model. Our study provides direct biochemical and biophysical evidence of structurally distinct novel type of ribosomes in intermediate eukaryotic flatworms. These finding may be important for re-recognition of biological protein synthesis and evolutionary process of living things