Ribosomal protein S12 as a site for streptomycin resistance in Nicotiana chloroplasts

Summary A streptomycin resistant Nicotiana plastome mutant, X/str ^R6, was subjected to molecular analysis. In this mutant, a single nucleotide transition, C » T, in the chloroplast gene for ribosomal protein S12 alters codon 90 from proline to serine while the nucleotide sequence of the chloroplast 16 S rRNA gene is identical to that of the wild type. Mutant X/str ^R6 thus differs from several previously reported streptomycin resistant chloroplast mutants which are altered in the gene for 16 S rRNA.     

Complementation in Nonconidiating Mutants of Trichoderma

Nonconidiating (Con(-)) mutants were isolated from wild-type and color mutants of the fungus Trichoderma viride Pers. ex Fries. Heterokaryons were easily produced and maintained, and the complementation relationships among the Con(-) mutants were established. Most Con(-) mutants could complement one or more of the other Con(-) mutants. When marked Con(-) mutants were mixed with marked Con(+) testers, conidiating heterokaryons were formed. The conidia thus obtained produced only the parental type colonies after replating, indicating that nonconidiation is a nuclear characteristic. Allowing two Con(-) colonies to meet and produce a heterokaryon, it was found that the migration of nuclei reached a rate of 5 mm per hr, which is several times greater than the rate of hyphal elongation; it was also found that heterokaryosis of a mycelial region preceded its ability to conidiate.     

Familial fragility on chromosome 16 (Fra 16q22) enhanced by both interferon and distamycin A

A family with a "fragile site" at 16q22, inducible by both interferon and Distamycin A, is reported. Immunological problems were found in the family. In a sibship of ten, eight children had died in infancy. Our study led to the conclusions that interferon and Distamycin A induce fragility at the same site, which has the same characteristics as the spontaneous fragile site; that a viral hypothesis for this fragility may be supported; and that immunoincompetence of one kind or another must be considered in families presenting a fragile site at 16q22.     

Genetic control of susceptibility to experimental allergic encephalomyelitis in mice

The genetic control of susceptibility to experimental allergic encephalomyelitis (EAE) was studied in mice. The results indicate that sensitivity to disease is not inherited in a simple Mendelian dominant way. Susceptibility to EAE is governed by genes located outside of the major histocompatibility complex and not byH-2-linkedIr genes. No correlation was observed between susceptibility to disease and the cellular immune response toward the small encephalitogenic protein.     

Highly phosphorylated bacterial proteins

We show in Gram-negative and Gram-positive bacteria the appearance of highly acidic proteins, which are highly phosphorylated. This group of proteins includes many cellular proteins, such as chaperones, biosynthetic, and metabolic enzymes. These proteins accumulate under stress conditions or under conditions, which overload the proteolytic system. Pulse chase experiments using radioactive phosphate indicate that the phosphorylated proteins have a short half-life, suggesting that they could be degradation intermediates. Moreover, results from in vitro experiments in Escherichia coli indicated that ribosomal proteins become susceptible to proteolysis after polyphosphorylation. Therefore, it is possible that the highly phosphorylated proteins represent a group of proteins tagged for degradation by phosphorylation. Such a tagging process may be involved in a general bacterial degradation pathway.     

Protein aggregation in Escherichia coli: role of proteases

Protein aggregation is involved in several human diseases, and presumed to be an important process in protein quality control. In bacteria, aggregation of proteins occurs during stress conditions, such as heat shock. We studied the protein aggregates of Escherichia coli during heat shock. Our results demonstrate that the concentration and diversity of proteins in the aggregates depend on the availability of proteases. Aggregates obtained from mutants in the Lon (La) protease contain three times more protein than wild-type aggregates and show the broadest protein diversity. The results support the assumption that protein aggregates are formed from partially unfolded proteins that were not refolded by chaperones or degraded by proteases.     

A novel founder mutation in the RNASEL gene, 471delAAAG,is associated with prostate cancer in Ashkenazi Jews

HPC1/RNASEL was recently identified as a candidate gene for hereditary prostate cancer. We identified a novel founder frameshift mutation in RNASEL, 471delAAAG, in Ashkenazi Jews. The mutation frequency in the Ashkenazi population, estimated on the basis of the frequency in 150 healthy young women, was 4% (95% confidence interval [CI] 1.9%-8.4%). Among Ashkenazi Jews, the mutation frequency was higher in patients with prostate cancer (PRCA) than in elderly male control individuals (6.9% vs. 2.4%; odds ratio = 3.0; 95% CI 0.6-15.3; P=.17). 471delAAAG was not detected in the 134 non-Ashkenazi patients with PRCA and control individuals tested. The median age at PRCA diagnosis did not differ significantly between the Ashkenazi carriers and noncarriers included in our study. However, carriers received diagnoses at a significantly earlier age, compared with patients with PRCA who were registered in the Israeli National Cancer Registry (65 vs. 74.4 years, respectively; P<.001). When we examined two brothers with PRCA, we found a heterozygous 471delAAAG mutation in one and a homozygous mutation in the other. Loss of heterozygosity was demonstrated in the tumor of the heterozygous sib. Taken together, these data suggest that the 471delAAAG null mutation is associated with PRCA in Ashkenazi men. However, additional studies are required to determine whether this mutation confers increased risk for PRCA in this population.