Inhibitory effect of a synthetic polypeptide, poly(Tyr-Ile-Gly-Ser-Arg), on the metastatic formation of malignant tumour cells

A new type of polypeptide containing the repeating sequence of cell attachment site in laminin, poly(Tyr-Ile-Gly-Ser-Arg), was synthesized by the polymerization procedure with diphenylphosphoryl azide (DPPA). We found that this polypeptide inhibited the metastatic formation in the lung of malignant tumour cells far more effectively than pentapeptide.     

Molecular evolution of catalytic antibodies in autoimmune mice.

Catalytic Abs (catAbs) preferentially evolved in autoimmune MRL/MPJ-lpr/lpr (MRL/lpr) mice upon immunization with the phosphonate transition-state analogue (TSA), but this did not happen in normal BALB/c mice. The majority of the catAbs from MRL/lpr mice were from several independent clones of the same family. Most of them had a lysine at position 95 in the heavy chain (H95), which is at the junctional region. This residue, which interacts with the phosphonate moiety of the TSA and presumably is involved in the catalytic activity, was not changed even after expansive evolution following multiple mutations. By contrast, the majority that arose from BALB/c mice were the non-catAbs, which were quite different in the sequence from the catAbs from MRL/lpr mice, but they were clonally related to one another, so most of them were originated from a single clone. In the MRL/lpr mice, the catalytic subsets that existed in the initial repertoire were effectively captured by the phosphonyl oxygens in the TSA by interacting with the lysine at H95. In the BALB/c mice, however, another noncatalytic subset with only the binding capability directed to a moiety other than the phosphonate moiety was alternatively evolved, because of the lowest abundance or elimination of the catalytic subsets.     

Profilin 1 mutants form aggregates that induce accumulation of prion-like TDP-43

Mutations in the profilin 1 (PFN1) gene have been identified as a cause of familial amyotrophic lateral sclerosis (ALS), and neuropathological studies indicate that TDP-43 is accumulated in brains of patients with PFN1 mutation. Here, we investigated the role of PFN1 mutations in the formation of prion-like abnormal TDP-43. Expression of PFN1 with pathogenic mutations resulted in the formation of cytoplasmic aggregates positive for p62 and ubiquitin, and these aggregates sequestered endogenous TDP-43. TDP-43 accumulation was facilitated in the presence of proteasome or lysosome inhibitor. Co-expression of mutant PFN1 and TDP-43 increased the levels of detergent-insoluble and phosphorylated TDP-43, and this increase required the C-terminal region of TDP-43. Moreover, detergent-insoluble fractions prepared from cells expressing ALS-linked mutant PFN1 induced seed-dependent accumulation of TDP-43. These findings indicate that expression of PFN1 mutants induces accumulation of TDP-43, and promotes conversion of normal TDP-43 into an abnormal form. These results provide new insight into the mechanisms of TDP-43 proteinopathies and other diseases associated with amyloid-like protein deposition.     

A new species of Trichogramma (Hymenoptera: Trichogrammatidae) parasitic on eggs of the alderfly Sialis melania (Neuroptera: Sialidae) from Japan,with comments on its phylogeny and male wing polymorphism

A new species of Trichogramma that parasitizes Sialis melania eggs is described as Trichogramma tajimaense Yashiro, Hirose and Honda, sp. nov. from Japan. Its phylogenetic position is based on a DNA‐based analysis, and data regarding its male wing polymorphism are also presented. The view that T. tajimaense is closely related to T. semblidis, another parasitoid of Sialis eggs, is supported by the results of a phylogenetic analysis, as well as by the biological and morphological similarities between both species. Trichogramma tajimaense is also similar in male wing polymorphism to T. kurosuae, a gregarious egg parasitoid of the lepidopteran Ivela auripes, as both Trichogramma species exhibit male wing trimorphism (fully alate, brachypterous and apterous forms) in contrast to the male wing dimorphism (fully alate and apterous forms) of T. semblidis. However, no phylogenetic analysis reveals a close relationship between T. tajimaense and T. kurosuae, and a difference exists between these two species in the mean percentage of flightless (brachypterous and apterous) males that emerge from a host egg mass; 96% of T. tajimaense males are incapable of flight, whereas about 50% of T. kurosuae males are flightless. Because all or almost all males of T. semblidis parasitizing Sialis eggs are apterous, T. tajimaense is more similar to T. semblidis than to T. kurosuae in the proportion of flightless males. In addition, male wing polymorphisms of Trichogramma in relation to mating systems could also show a similarity between T. tajimaense and T. semblidis when considering both species as quasi‐gregarious parasitoids of Sialis eggs.     

Salt tolerance and glycerol accumulation of a respiration-deficient mutant isolated from the petite-negative, salt-tolerant yeast Zygosaccharomyces rouxii

A respiration-deficient (RD) mutant was isolated from the petite-negative, salt-tolerant yeast Zygosaccharomyces rouxii. One strain among sixteen glycerol-non-utilizing mutants exhibited vigorous liberation of CO2 but no uptake of O2. Furthermore, this strain lacked cytochrome aa3 and had a reduced level of cytochrome b. The few mitochondria found in cells of this strain contained few or no cristae. Salt tolerance and intracellular accumulation of glycerol by the RD strain were almost equal to that of the wild-type strain in media containing NaCl up to 2.5 M. In media with more than 3 M NaCl, the growth of the RD mutant was retarded and the intracellular accumulation of glycerol was depressed in spite of ample production.     

Comparison between parental and variant soybeanBradyrhizobium strains with regard to the production of lipo-chitin nodulation signals,early stages of root infection,nodule occupancy,and N2 fixation rates

Soybean is the most important leguminous crop in Brazil and the nitrogen required for plant growth is supplied byBradyrhizobium bacteria through the symbiotic relation established by the inoculation process. Since 1992, two new strains, CPAC 7 and CPAC 15, which have been shown to increase yields in several field experiments, have been recommended in Brazilian commercial inoculants. CPAC 15 is a natural variant of theB. elkanii SEMIA 566 strain, and was isolated after several years of adaptation to a Brazilian Cerrado soil, while CPAC 7 is a variant ofB. japonicum strain CB 1809, selected under laboratory conditions for higher nodulation and yield. The comparison between parental and variant strains, under greenhouse conditions, showed that both CPAC 15 and CPAC 7 increased N₂ fixation rates in relation to the parental strains. The better performance of CPAC 15 was related to an increase in nodule efficiency (mg N₂ fixed mg^-1 nodule) while with CPAC 7 the higher N₂ fixation rates were due to increased nodulation. Both CPAC 15 and CPAC 7 increased nodule occupancy, when co-inoculated at a ratio of 1:1 withB. elkanii 29w, in relation to their parental strains. Variant strains also differed from parental in their ability to increase numbers of root hairs (Hai phenotype) either when inoculated onto plants, or when supernatants of bacteria exposed to seed exudates were used as inoculants. This results lead to the hypothesis that a modification in some of the “common” nodulation genes had occurred. However, the increase in Hai phenotype with CPAC 7 was dependent on the soybean cultivar, indicating a possible alteration in some genotypic specific nodulation gene. Apparently, there were no differences in Nod metabolites produced by strains CPAC 15 and SEMIA 566, but a more detailed chemical analysis would be required to rule out subtle differences. On the contrary, significant differences were found between CPAC 7 and the parental strain CP 1809, in the profile of Nod metabolites. Consequently, it may be possible that diffusable molecules, responsible for Hai phenotype, would be related to nodulation ability, competiviveness, and N₂ fixation, resulting in the higher yields that have been associated with CPAC 7 and CPAC 15. For the CPAC 7 strain, the increase in Hai phenotype could be atributed to the differences found in the Nod molecules. Consequently, a high degree of physiological and genetic variability can result from the adaptation of rhizobial strains to the soil. Also, this variability can be found under laboratory conditions, when searching single colonies with specific properties. ei]Section editor: R O D Dixon     

Subtractive screening of genes involved in cellular senescence

We attempted to identify the genes involved in cellularsenescence, telomere maintenance and telomerase regulationthrough subtractive screening of cDNA libraries prepared froma human lung adenocarcinoma cell line A549 and its sublinesnamed A5DC7, CK and AST-9. Cell phenotypes of A5DC7, CK andAST-9 are normal cell-like, cancer cell-like and intermediate,respectively. These cell lines have different phenotypes interms of telomerase activity and telomere maintenance, andthus are thought to be useful for identifying the genesinvolved in cellular senescence and telomerase regulation. In this study, we identified 86 independent cDNA clones bysubtractive screening. Among these cDNA clones, subtractingA5DC7 cDNAs from A549 cDNAs and CK cDNAs gave 7 and 3 cDNAclones which highly and specifically expressed in tester celllines. Genes corresponding to these 10 cDNA clones mightparticipate in maintaining cancer-cell phenotypes. As aresult of database searching, each four of A549 specific cDNAclones are found to correspond to known cDNAs. Each two ofA549 specific and two of CK specific cDNA clones have highhomology to independent ESTs. Sequences having homology toeach one of A549 specific and one of CK specific cDNA cloneshave not been deposited in the Genbank database, indicatingthat these two cDNA clones are part of novel genes. Weanticipate that their involvement in telomerase regulationand/or senescence program can be clarified by functionalanalysis using each full-length cDNA.