Investigating hypothetical products from noncoding frames (HyPNoFs)

Hypothetical Products from Noncoding Frames (i.e., HyPNoFs) are hypothetical, not-coded proteins, translated from alternate reading frames (i.e., coding+1 and coding+2) of cDNAs. HyPNoFs of CD4, PKC, oncostatin, bcl-2 proto-oncogene, tumor suppressor p53, cystic fibrosis transmembrane regulator (CFTR), and tumor necrosis factors a and were searched as query sequences vs the SWISS-PROT data bank. Homology searches carried out revealed that hypothetical products (i.e., HyPNoFs) may share high similarity with real protein products actually coded. Sequence similarity of hypothetical products to real proteins is sometimes very high, suggesting common conformational features, according to the Sander and Schneider cutoff value. This finding supports the hypothesis that eukaryotic DNA, currently considered to be monocistronic, might occasionally have polycistronic regions, carrying different protein messages on overlapping frames. As yet, polycistronic genes have been observed in viral genomes only. The presence of polycistronic regions in eukaryotic genes is likely reminiscent of an ancient strategy, rather than a present feature of the genome in eukaryotes.These data suggest that thorough investigation of HyPNoFs is likely to improve our ability to trace genes' evolution and to investigate structure-function relationships of protein and DNA sequences.     

Subnucleolar location of fibrillarin and variation in its levels during the cell cycle and during differentiation of plant cells

The nucleolar protein fibrillarin has been studied in onion cells; it is detected as an Mr 37,000 protein by immunoblotting using a human autoimmune serum. Quantitative immunoelectron microscopy showed that most fibrillarin is localized in the transition zone between the fibrillar center (FC) and the dense fibrillar component (DFC) as well as in the priximal zone of the DFC, where the labeling shows a gradual decrease out-ward until it reaches insignificant levels in the distal zone of the DFC. Thus, fibrillarin is not uniformly distributed throughout the DFC of plant cells. This result supports the hypothesis that the morphologically homogeneous DFC may not be uniform in function; it is also in agreement with the hypothesized vectorial flow of ribosome biogenesis through the same compartments. Data are also presented showing that the amount of fibrillarin increase when nucleolar activity increases in G2, and probably decreases when nucleolar activity decreases during differentiation.     

Nucleolar cycle and localization of NORs in early embryos of Parascaris univalens

During early embryogenesis of the nematode Parascaris univalens (2n=2) the processes of chromatin diminution and segregation of the germ and somatic cell lineages take place simultaneously. In this study we analyzed the nucleolar cycle in early embryos, both in germinal and somatic blastomeres, by means of silver staining and antibodies against the nucleolar protein fibrillarin. We observed an identical nucleolar cycle in both types of blastomeres, hence, the chromatin diminution process has no effect on the nucleolar cycle of somatic blastomeres. We report the existence of outstanding differences between this cycle and those previously reported during early embryogenesis of other species. There is a true nucleolar cycle in early embryos that shows a peculiar nucleolar disorganization at prophase, and a preferential localization of prenucleolar bodies only on the euchromatic regions during nucleologenesis. Moreover, fibrillarin does not form a perichromosomal sheath in metaphase or anaphase holocentric chromosomes, probably owing to their special centromeric organization. The number and location of nucleolus organizer regions (NORs) in the chromosomal complement have been determined using silver impregnation, chromomycin A₃/distamycin A staining, and fluorescent in situ hybridization using an rDNA probe. There are only two NORs, one per chromosome, and these are lost in blastomeres after chromatin diminution. Moreover, the constant presence of two nucleoli in somatic blastomeres suggests that NORs are not affected during the fragmentation of euchromatic regions when this process occurs.     

Comparative mapping of the DiGeorge syndrome region in mouse shows inconsistent gene order and differential degree of gene conservation

We have constructed a comparative map in mouse of the critical region of human 22q11 deleted in DiGeorge (DGS) and Velocardiofacial (VCFS) syndromes. The map includes 11 genes potentially haploinsufficient in these deletion syndromes. We have localized all the conserved genes to mouse Chromosome (Chr) 16, bands B1-B3. The determination of gene order shows the presence of two regions (distal and proximal), containing two groups of conserved genes. The gene order in the two regions is not completely conserved; only in the proximal group is the gene order identical to human. In the distal group the gene order is inverted. These two regions are separated by a DNA segment containing at least one gene which, in the human DGS region, is the most proximal of the known deleted genes. In addition, the gene order within the distal group of genes is inverted relative to the human gene order. Furthermore, a clathrin heavy chain-like gene was not found in the mouse genome by DNA hybridization, indicating that there is an inconsistent level of gene conservation in the region. These and other independent data obtained in our laboratory clearly show a complex evolutionary history of the DGS-VCFS region. Our data provide a framework for the development of a mouse model for the 22q11 deletion with chromosome engineering technologies. Received: 8 July 1997 / Accepted 11 August 1997     

Differential effects of five types of antipathogenic plant peptides on model membranes

The effects of five antipathogenic plant peptides, wheat α-thionin, potato PTH1 defensin, barley LTP2 lipid transfer protein, and potato tuber DL1 and DL2 defensins, have been tested against phospholipid vesicles (liposomes). Wheat thionin very actively induces aggregation and leakage of negatively charged vesicles. LTP2 displays the same activities, although to a limited extent. Under certain conditions PTH1 and DL2 induce vesicle aggregation, but not leakage. Potato defensin DL1 failed to show any effect on liposomes. The same peptides have been assayed against a plant pathogenic bacterium, both the membrane-active and -inactive compounds having efficient antibacterial action.     

Diet and Health

The role of diet in personal health maintenance is important whether a person is trying to stay healthy or to treat diet-related diseases such as hypercholesterolemia, hypertension, diabetes mellitus or obesity. Dietary recommendations include limiting fat to 30% and protein to 20% of total calories, with the remaining 50% coming from carbohydrate. Maintaining dietary changes for long periods is very difficult for many persons. Specific self-management skills may ease the task.     

Febrile Gastroenteritis Due to Salmonella thompson—Report of an Outbreak

Salmonella thompson, a common pathogen of poultry, has received scant attention as a cause of human gastroenteritis. At least 45 persons were infected with S thompson in Sacramento, California, after eating at a chicken restaurant and 38 became symptomatic. Ten required admission to hospital, and all were treated with antibiotics and improved. In 19 cases cultures of stool specimens for S thompson over a 60-day period showed slower but statistically insignificant differences in salmonellal elimination in 7 patients who received antibiotics when compared with 12 who were untreated. We report this outbreak to increase awareness of the virulence and prevalence of gastroenteritis due to S thompson.     

Malic acid production and consumption by selected of Saccharomyces cerevisiae under anaerobic and aerobic conditions

Summary Fermentation tests in clearly defined laboratory conditions were carried out with eight functionally selected strains of Saccharomyces cerevisiae. Analysis of the data showed that there were no significant differences in malic acid production between the strains when the acid was initially present. When it was initially absent, however, significant differences were observed two strains (Nos. 1141 and 1083) showing marked productive superiority. With malic acid as the sole C source, two strains (Nos. 1109 and 1141) showed less acid consumption.     

Lethality and mutagenicity inHalobacterium mediterranei caused by N-methyl-N′-nitro-N-nitrosoguanidine

Compared withEscherichia coli, Halobacterium mediterranei was highly resistant to the lethal effect of N-methyl-N-nitro-N-nitrosoguanidine (nitrosoguanidine), but it was sensitive to the mutagenic action of this chemical agent. Nitrosoguanidine at 500 g ml^–1 gave a cell survival level between 1% and 10%, and this allowed us to obtain more Josamycin-resistant mutants compared with lower concentrations, which gave higher survival rates but fewer mutants. The efficiency of the mutagenicity obtained with the nitrosoguanidine treatment was examined under a variety of conditions. The optimal conditions for obtaining Josamycinresistant mutants were achieved by exposing, in darkness and without shaking, a suspension of about 10⁸ log-phase cells to 500 g nitrosoguanidine in 1 ml of 50 mM modified saline Tris-maleate buffer at pH 7.5, or in 1 ml of 5 mM modified saline Tris-citrate-maleate for 30 min at 37°C.