Hepatitis B vaccination in predialysis chronic renal failure patients a comparison of two vaccination schedules

To improve seroconversion to hepatitis B vaccination, it is recommended that patients suffering with chronic renal failure be vaccinated as soon as dialysis is anticipated. We compared seroconversion rates in 121 predialysis patients with moderate chronic renal failure using either 40 or 20 microg of Engerix B recombinant hepatitis B vaccine administered at 0, 1 and 6 months. Seroconversion was not significantly higher after three doses of 40 microg (67%) compared to 20 microg (57%, p=0.27). Multivariable analysis using dose of vaccine, eGFR (MDRD equation), calculated creatinine clearance (Cockcroft--Gault), and age as independent continuous variables showed that neither dose nor degree of renal function contributed to seroconversion. Younger age was weakly associated with improved seroconversion (p=0.052). Seroconversion was attained in 13% of non-responders after a fourth dose of vaccine.

Effect of disruption of a cutinase gene (cutA) on virulence and tissue specificity of Fusarium solani f. sp. cucurbitae race 2 toward Cucurbita maxima and C. moschata

A 3.9-kb genomic DNA fragment from the cucurbit pathogen Fusarium solani f. sp. cucurbitae race 2 was cloned. Sequence analysis revealed an open reading frame of 690 nucleotides interrupted by a single 51-bp intron. The nucleotide and predicted amino acid sequences showed 92 and 98% identity, respectively, to those of the cutA gene of the pea pathogen F. solani f. sp. pisi. A gene replacement vector was constructed and used to generate cutA- mutants that were detected with a polymerase chain reaction (PCR) assay. Seventy-one cutA- mutants were identified among the 416 transformants screened. Vector integration was assessed by Southern analysis in 23 of these mutants. PCR and Southern analysis data showed the level of homologous integration was 14%. Disruption of the cutA locus in mutants was confirmed by RNA gel blot hybridization. Neither virulence on Cucurbita maxima cv. Delica at any of six different inoculum concentrations, nor pathogenicity on intact fruit of four different species or cultivars of cucurbit or hypocotyl tissue of C. maxima cv. Crown, was found to be affected by disruption of the cutA gene.

Gene inactivation in the plant pathogen Glomerella cingulata: three strategies for the disruption of the pectin lyase gene pnlA

The feasibility of performing routine transformation-mediated mutagenesis in Glomerella cingulata was analysed by adopting three one-step gene disruption strategies targeted at the pectin lyase gene pnlA. The efficiencies of disruption following transformation with gene replacement- or gene truncation-disruption vectors were compared. To effect replacement-disruption, G. cingulata was transformed with a vector carrying DNA from the pnlA locus in which the majority of the coding sequence had been replaced by the gene for hygromycin B resistance. Two of the five transformants investigated contained an inactivated pnlA gene (pnlA-); both also contained ectopically integrated vector sequences. The efficacy of gene disruption by transformation with two gene truncation-disruption vectors was also assessed. Both vectors carried at 5' and 3' truncated copy of the pnlA coding sequence, adjacent to the gene for hygromycin B resistance. The promoter sequences controlling the selectable marker differed in the two vectors. In one vector the homologous G. cingulata gpdA promoter controlled hygromycin B phosphotransferase expression (homologous truncation vector), whereas in the second vector promoter elements were from the Aspergillus nidulans gpdA gene (heterologous truncation vector). Following transformation with the homologous truncation vector, nine transformants were analysed by Southern hybridisation; no transformants contained a disrupted pnlA gene. Of nineteen heterologous truncation vector transformants, three contained a disrupted pnlA gene; Southern analysis revealed single integrations of vector sequence at pnlA in two of these transformants. pnlA mRNA was not detected by Northern hybridisation in pnlA- transformants. pnlA- transformants failed to produce a PNLA protein with a pI identical to one normally detected in wild-type isolates by silver and activity staining of isoelectric focussing gels. Pathogenesis on Capsicum and apple was unaffected by disruption of the pnlA gene, indicating that the corresponding gene product, PNLA, is not essential for pathogenicity. Gene disruption is a feasible method for selectively mutating defined loci in G. cingulata for functional analysis of the corresponding gene products.

The pectin lyase-encoding gene (pnl) family from Glomerella cingulata: characterization of pnlA and its expression in yeast

Oligodeoxyribonucleotide primers were designed from conserved amino acid (aa) sequences between pectin lyase D (PNLD) from Aspergillus niger and pectate lyases A and E (PELA/E) from Erwinia chrysanthemi. The polymerase chain reaction (PCR) was used with these primers to amplify genomic DNA from the plant pathogenic fungus Glomerella cingulata. Three different 220-bp fragments with homology to PNL-encoding genes from A. niger, and a 320-bp fragment with homology to PEL-encoding genes from Nicotiana tabacum and E. carotovora were cloned. One of the 220-bp PCR products (designated pnlA) was used as a probe to isolate a PNL-encoding gene from a lambda genomic DNA library prepared from G. cingulata. Nucleotide (nt) sequence data revealed that this gene has seven exons and codes for a putative 380-aa protein. The nt sequence of a cDNA clone, prepared using PCR, confirmed the presence of the six introns. The positions of the introns were different from the sites of the five introns present in the three PNL-encoding genes previously sequenced from A. niger. PNLA was synthesised in yeast by cloning the cDNA into the expression vector, pEMBLYex-4, and enzymatically active protein was secreted into the culture medium. Significantly higher expression was achieved when the context of the start codon, CACCATG, was mutated to CAAAATG, a consensus sequence commonly found in highly expressed yeast genes. The produced protein had an isoelectric point (pI) of 9.4, the same as that for the G. cingulata pnlA product.(ABSTRACT TRUNCATED AT 250 WORDS)

Unusual features of transcribed and translated regions of the histone H4 gene family of Tetrahymena thermophila

The complete DNA sequence is presented of H4-II, the second of the pair of histone H4 genes of the ciliated protozoan, Tetrahymena thermophila. Both H4 genes code for the same protein. Codon usage in these and other Tetrahymena genes is severely restricted and is similar to that in yeast. Flanking regions are AT-rich (greater than or equal to 75%), relative to coding sequences (approximately 45% GC). Except for small, similarly positioned homologies, flanking sequences of the two genes are different. Canonical sequences in higher eukaryotic promoters are not obvious in these genes. Instead, short, localized, base composition eccentricities characterize the 5' flanking sequences of all Tetrahymena genes analyzed. The consensus, P yP u(A)3-4 ATGG initiates translation in these and all other known Tetrahymena genes. Nuclear transcripts and messages of both growing and starved cells begin at multiple sites, mainly at the first or second A residue following a pyrimidine. The palindrome typical of histone message 3' termini in higher organisms is not present. Downstream of both genes are sequences similar to the processing/polyadenylation signal of higher eukaryotes, although the unique 3' ends are not those predicted by the location of the signals.

Tetrahymena H4 genes: structure, evolution and organization in macro- and micronuclei

The ciliated protozoan Tetrahymena thermophila contains two types of H4 histone genes (H4-I and H4-II). Southern blotting and analysis of DNA from nullisomic strains indicate that H4-I and H4-II are on different chromosomes and that only H4-II is closely linked to an H3 gene. No DNA sequence rearrangements are observed for either of the H4 genes when the transcriptionally inert, germ line, micronucleus is compared to the transcriptionally active, somatic macronucleus. Comparison of the H4-I gene and its flanking sequences to H4 gene sequences of other organisms indicates that there are evolutionary constraints on coding nucleotides that are unrelated to their protein coding function and that these evolutionary pressures operate at the level of translation.

Multiple, independently regulated, polyadenylated messages for histone H3 and H4 in Tetrahymena

Heterologous probes for yeast H4 and H3 histone genes have been used to study the corresponding histone mRNAs in growing and starved Tetrahymena. Histone mRNAs in both physiological states are polyadenylated. Two types of H4 protein and two types of H3 protein have previously identified in Tetrahymena. Two size classes of H4 messages and three classes of H3 messages have been detected by northern analyses. Southern blot analysis indicate that the number of different kinds of H3 and H4 genes is the same or slightly greater than the number of different messages, suggesting that each message is derived from a different gene. Growing cells have -30 times more histone mRNA than starved cells, even though their total mRNA content is only 4 times greater. The relative abundance of different H4 and H3 messages in growing and starved cells is different, demonstrating that the different messages for a particular type of histone are regulated non-coordinately. In starved cells the presence of a single size class of H3 messages correlates with the preferential synthesis of a previously described macronuclear-specific H3 variant. The fraction of histone messages loaded in growing and starved cells is the same as for bulk mRNAs, and the relative concentrations of the multiple messages for H4 and H3 are the same in polysomal and total RNAs of each cell type. These observations suggest that histone synthesis in Tetrahymena is controlled largely at the level of message abundance, and that very little, if any, control occurs at the translational level.

Histone variants specific to the transcriptionally active, amitotically dividing macronucleus of the unicellular eucaryote, Tetrahymena thermophila

Two dimensional gel electrophoresis (triton-acid-urea followed by SDS) has been used to resolve two previously uncharacterized, quantitatively minor histone variants in acid extracts from macronuclei of Tetrahymena thermophila. Utilizing techniques which allow characterization of these variants without purifying them in significant quantities, we identify one protein as a subtype of H3. The other protein is a moderately lysine-rich histone whose tryptic peptide map differs from that of both H2A and H2B. However, its pattern of secondary modifications, its detergent-binding properties and its methionineless nature all suggest that it is more like H2A than any other histone. Both variants are associated with nucleosomes derived from macronuclei. Thus primary sequence variants of the inner histones, presumably indicative of nucleosome heterogeneity, exist in a lower eucaryote, in an amitotic nucleus, and within the nucleus of a clonally propagated organism. Evidence is presented that these newly described minor variants are absent in micronuclei, suggesting that they play an important role in the structural and functional differentiation of macronuclear chromatin.

Proteolytic processing of histone H3 in chromatin: a physiologically regulated event in Tetrahymena micronuclei

Micronuclei of Tetrahymena thermophila contain two electrophoretically distinct forms of histone H3. The slower migrating micronuclear species, H3S, is indistinguishable from the macronuclear H3 by electrophoretic analyses in three gel systems and by partial proteolytic peptide mapping. The faster species, H3F, is unique to micronuclei. Pulse-chase experiments with radioactive amino acids show that H3S is a precursor to H3F. We present evidence that the in vivo processing of H3S into H3F requires cell growth and/or division and may occur regularly each generation at a specific point in the cell cycle. The processing event must occur after H3F is deposited on micronuclear chromatin, since both H3S and H3F can be isolated from sucrose gradient-purified mononucleosomes (Allis, Glover and Gorovsky, 1979). Partial proteolytic peptide mapping coupled with 3H-N-ethylmaleimide labeling suggest that the processing event involves a proteolytic cleavage from the amino terminal end of H3F. Automated sequence analyses of 14C-lysine-labeled macronuclear H3 together with either 3H-lysine-labeled H3S or H3F demonstrated that H3F is derived from H3S by a proteolytic cleavage which removes six residues from the amino terminus. These observations represent the first demonstration of a physiologically regulated proteolytic processing event in histone metabolism.