Mutants of model eukaryotic organisms have revealed that most ribosomal proteins are essential for cell viability. However, the precise functional role of each ribosomal protein is largely unknown. Recent reports on the involvement of ribosomal proteins in various genetic diseases and studies on the extraribosomal functions of these proteins have cast some light on their localization and functions. Here we prepared rabbit polyclonal antibodies against 26 human ribosomal proteins; each of these reagents recognized a single band in immunoblots of the purified ribosome. We used these antibodies to evaluate a panel of human cancer cell lines. Although no deficiency of ribosomal proteins was observed, the abundance of S11 and S30 varied substantially among the cell lines, but the difference did not affect the biogenesis or composition of the ribosome. Therefore, the heterogeneity may be related to extraribosomal functions of S11 and S30. The antibodies described here are powerful tools for research into the molecular mechanisms of protein translation, cell-biological and medical studies on the ribosomal proteins, and ultimately a comprehensive understanding of all ribosomal proteins ("ribosomics"). Key words: Proteomics -Ribosomal proteins -Antibodies -Expression profiles -Human cancerAll living organisms have ribosomes, which are a protein complex that is essential for protein synthesis. Bacterial ribosomes are an excellent in vivo model system that has been studied for a long time, and much information on the roles of the ribosome in translation has accumulated.

We screened alkaliphilic bacteria from the first proctodaeal region (P1) of the hindgut, which is known to show high alkalinity and K + richness, of several species of higher termites. Phylogenetic analyses based on the 16S rDNA sequence revealed that most isolates were affiliated with known alkaliphilic bacilli, frequently isolated from soil. Though many physiological characteristics of the isolated strains were similar to those of soil alkaliphilic bacilli, some strains showed a distinctive NaCl sensitivity. Many strains grew better in an alkaline medium containing K 2 CO 3 than one containing Na 2 CO 3 . One strain, closely related to the xylanolytic and alkaliphilic Paenibacillus sp. SM-XY60 from the soil-feeding termite Sinocapritermes mushae, was also isolated. Culture-independent analysis showed that bacteria closely related to our isolated alkaliphiles widely inhabit the termite gut. Our results also suggested that some alkaliphilic bacilli in soil share ecological niches in the termite gut.

Stimulation of death receptors (Fas on human T-cell leukemia Jurkat cells and tumor necrosis factor receptor-1 on human monoblastic leukemia U937 cells) triggers the specific degradation of 28S ribosomal RNA, and this process may contribute to cell death through the inhibition of protein synthesis. We have developed an analytical method using a polyacrylamide-agarose composite gel to evaluate ribosomal subunits in apoptotic cells (human breast carcinoma MCF-7 cells treated with staurosporine and human 293T cells irradiated with ultraviolet light were used in addition to the two apoptosis systems described above). No alterations were detected by this method, suggesting that apoptosis, including the process of ribosomal RNA degradation, does not cause fragmentation or extensive conformational changes in the ribosome. We also examined the status of 21 different ribosomal proteins in apoptotic cells by immunoblotting with polyclonal antibodies. S11 was specifically downregulated in apoptotic MCF-7 cells and in other apoptotic breast carcinoma cells. Previous studies have shown that S11 is heterogeneously expressed in cancer cells. Taken together, it appears that particular intracellular environments regulate the expression of S11 protein. However, the mechanism by which this process is modulated is as yet unknown. Furthermore, we have demonstrated that our composite gel electrophoresis system can efficiently detect ubiquitination of ribosomal subunits.

Adsorption of infectious hematopoietic necrosis virus (IHNV) to sea sand, Japanese acid clay, diatomaceous earth, kaolin, bentonite, quartz sand, chitin, cellulose powder, ion exchange hydrophobic Toyopeal and Cellulofine, alundum, active carbon, silica gel, glass, plastic, and bacterial cells was studied. The IHNV adsorbed to several clays (kaolin, bentonite, Japanese acid clay) and diatomaceous earth in sterilized water with a wide range of pH (5-11) at concentrations of 1, 10, and 100 mg/mL. Except for bentonite, infectivity of clay-adsorbed IHNV persisted for as long as 9 weeks. The clay-adsorbed IHNV also persisted in infectivity to rainbow trout Oncorhynchus mykiss, causing cumulative mortality rates of more than 73%. The results suggest that IHNV adsorbed to naturally occurring substances in various aquatic environments may provide a source of infection for susceptible fish inhabiting these environments.