Independent genes coding for three acidic proteins of the large ribosomal subunit from Saccharomyces cerevisiae

The yeast ribosome contains three acidic proteins, L44, L44', and L45, closely related from a structural point of view, that seem to play a functional role similar to that of proteins L7 and L12 in the bacterial ribosome. By screening a cDNA bank in lambda gt11 with specific polyclonal and monoclonal antibodies, recombinant phages expressing each one of the acidic proteins have been cloned. A unique copy of each gene is detected using the phage cDNA inserts as probes in nitrocellulose blots of yeast DNA digested with different restriction enzymes. The inserts were subcloned in the plasmid pUC19, and their physical maps and nucleotide sequences were determined. By using the cDNA inserts as probes in genomic DNA banks, DNA fragments carrying the acidic protein genes have been cloned, characterized, and sequenced. The results conclusively show that the three yeast acidic proteins are coded by independent genes and are not the result of a post-translational modification of the product of a unique gene, as in bacteria. Like most ribosomal protein genes, the gene for protein L44' has an intron and two upstream stimulatory boxes (UASrpg) fitting closely to the consensus sequence. The genes coding for proteins L44 and L45 lack introns and seem also exceptional in other characteristics of their sequences. Proteins L44 and L45 have amino acid sequences with about 80% similarity. Protein L44' is only 63% similar to the other two polypeptides. The three proteins have highly conserved carboxyl termini comprising the last 30 amino acids, and the first 10 amino acids of L44 and L45 are identical. The results cast doubts about the possibility of a similar role for the different acidic ribosomal proteins.     

Normal thymic cortical epithelial cells developmentally regulate the expression of a B-lineage transformation-associated antigen

Nonlymphoid, stromal cells in the mouse thymus are believed to be important in T cell maturation and have been proposed to play a central role in the acquisition of major histocompatibility complex (MHC) restriction and self-tolerance by maturing thymocytes. Both cortical and medullary epithelial cells in the thymus express high levels of class II (A) major histocompatibility antigens (MHC Ags). We show here that a specific subset of these A^– epithelial cells express a transformation-associated antigen (6C3Ag) found previously on the surfaces of Abelson murine leukemia virus-transformed pre-B cells and on those bone marrow-derived stromal cell clones which support normal and preneoplastic pre-B cell proliferation. Among solid lymphoid organs, only the thymus contains 6C3Ag¹ cells and within the thymus, this antigen is found exclusively on A^– epithelial cells in cortical regions. It is striking that the expression of the 6C3Ag on thymic epithelium is developmentally regulated, suggesting a role for this lymphostromal antigen in the maturation of the thymic microenvironment.     

Entry of [(1,2-13C2)acetyl]-L-carnitine in liver tricarboxylic acid cycle and lipogenesis: a study by 13C NMR spectroscopy in conscious, freely moving rats.

The biochemical pathways involved in acetyl-L-carnitine utilization were investigated in conscious, freely moving rats by 13C NMR spectroscopy. Following 4-h [(1,2-13C2)acetyl]-L-carnitine infusion in fasted animals, the free carnitine levels in serum were increased, and an efflux of unlabelled acetyl-L-carnitine from tissues was observed. [(1,2-13C2)Acetyl]-L-carnitine was found to enter biosynthetic pathways in liver, and the acetyl moiety was incorporated into both cholesterol and 3-hydroxybutyrate carbon skeleton. In accord with the entry of [(1,2-13C2)acetyl]-L-carnitine in the mitochondrial acetylCoA pool associated with tricarboxylic acid cycle, the 13C label was also found in liver glutamate, glutamine, and glutathione. The analysis of the 13C-labelling pattern in 3-hydroxybutyrate and cholesterol carbon skeleton provided evidence that the acetyl-L-carnitine-derived acetylCoA pool used for ketone bodies synthesis in mitochondria was homogeneous, whereas cholesterol was synthesized from two different acetylCoA pools located in the extra- and intramitochondrial compartment, respectively. Furthermore, cholesterol molecules were shown to be preferentially synthesized by the metabolic route involving the direct channelling of CoA-activated mitochondria-derived ketone bodies into 3-hydroxy-3-methylglutarylCoA pathway, prior to equilibration of their acyl groups with extramitochondrial acetylCoA pool via acetoacetylCoA thiolase.     

Long-term effects of postovulatory aging of mouse oocytes on offspring: a two-generational study.

Aims of this study were to analyze the long-term effects of postovulatory aging of mouse oocytes on 1) reproductive traits of parental (F(0)) and first (F(1))-generation females (pregnancy rate, gestation length, litter size, perinatal death, and sex ratio of offspring) and 2) developmental and behavioral variables of F(1) and second-generation (F(2)) offspring (birth weight and weight gain during preweaning development, postnatal day of attainment of immediate righting, spontaneous motor activity, and passive and active conditioned learning ability). Hybrid (C57BL/6JIco x CBA/JIco) females were artificially inseminated at 13 h (control group) or 22 h (oocyte-aged group) after GnRH injection. Experimental (oocyte-aged group) F(0) females exhibited lower pregnancy rate, shortened gestation length, decreased litter size, higher perinatal death of their pups, and increased percentage of male offspring compared to control F(0) females. Postovulatory aging of oocytes was also associated with increased number of growth-retarded pups, delayed development of the righting reflex, and higher spontaneous motor activity and emotionality of F(1) offspring. Postovulatory aging of F(0) oocytes did not affect birth weight, weight gain during preweaning development, passive and active conditioned learning ability of F(1) offspring, or reproductive traits of F(1) females or developmental and behavior variables of F(2) offspring.     

Growth ofEscherichia coli B in a continuous culture under limitation by inorganic phosphate

During batch cultivation ofEscherichia coli in a medium deficient in inorganic phosphate, the growth curve after exhaustion of phosphate is linear. Results obtained in batch cultivation were used for deriving expressions for bacterial growth at a constant rate in a single-and multi-stage continuous system. It was found experimentally that the theoretical relations derived are satisfactory.     

Sex pheromones of the moth, Archips podana: isolation, identification and field evaluation of two synergistic geometrical isomers

By means of analytical and electroantennogram methods, cis-11-and trans-11-tetradecenyl acetate have been isolated and identified as the sex pheromones of the fruit tree tortrix moth, Archips podana. In contrast to the single compounds, mixtures in a ratio of about 1 : 1 are highly attractive to male moths in field experiments.