Intergeneric antigenic relation of Hafnia and Shigella (S. flexneri and S. boydii) bacteria

The O-antigenic relationships between Hafnia and Shigellae (S. flexneri and S. boydii) have been studied. For the first time the presence of antigenic relationship between Hafnia O19, O4, O9, O33, O5, O16, O12, O7, O29, O28, O10, O32, O24, O25, O18, O1, O13, O3, O22, O30, O37, O14, O11, O25, O23, O21, O28, O16, O24, O8, O26, O27 and S. flexneri la, lb, 2a, 2b, 4a, 4b, 6, 5a, 5b, as well as between Hafnia O10, O21, O35, O36, O9, O28, O8, O30 and S. boydii 1, 3, 6, 14, 2, 5, 2, 12 have been revealed. The character and degree of manifestation of antigenic relationships between the above-mentioned groups of bacteria have been established.     

Structures of lipopolysaccharides from Klebsiella pneumoniae. Eluicidation of the structure of the linkage region between core and polysaccharide O chain and identification of the residues at the non-reducing termini of the O chains

Deamination of LPSs from Klebsiella pneumoniae released O-chain polysaccharides together with a fragment of the core oligosaccharide. The structures of the products from serotypes O1, O2a, O2a,c, O3, O4, O5, and O12 were determined by NMR spectroscopy and chemical methods, identifying the linkage region between the O antigens and the core as well as novel residues at the non-reducing ends of the polysaccharides. All serotypes had an identical linkage between the O chain and core.     

Cloning and sequence of a region encoding a surface polysaccharide of Vibrio cholerae O139 and characterization of the insertion site in the chromosome of Vibrio cholerae O1

Vibrio cholerae serogroup O139 Bengal is the first documented serogroup other than O1 to cause epidemic cholera. The O139 Bengal strains are very similar to V. cholerae serogroup O1 biotype El Tor strains. The major differences between the two serogroups are that O139 Bengal contains a distinct O antigen and produces a polysaccharide capsule. We previously described three Tn phoA mutants of O139 strain AI1837 which abolish both O antigen and capsule production. These Tn phoA insertions were mapped to a 21.5 kb Eco RI fragment of the O139 chromosome. We describe here the cloning and mapping of this 21.5 kb Eco RI fragment and it was shown to complement each of the mutants in trans to produce O antigen and capsule. The Eco RI fragment contains 13 kb of DNA that is specific to O139 and 8.5 kb of DNA that is common to O1 and O139. Sequence analysis of the 13 kb of O139-specific DNA revealed that it contains 11 open reading frames all of which are transcribed in the same direction. Eight of the 11 open reading frames are homologous to sugar biosynthesis genes from other organisms. Using extended polymerase chain reactions, we show that the extent of the DNA region in O139 that is not present in O1 is approximately 35kb. The site of insertion of this O139-specific DNA in the O1 chromosome was mapped to the rfb _O1 region. We also demonstrate that O139 Bengal strain AI1837 contains a deletion of 22 kb that in serogroup O1 strains contains the rfb region. Therefore, O139 Bengal probably arose from an O1 strain that had undergone genetic rearrangements including deletion of the O1 rfb region and acquisition of a 35 kb region of DNA which encodes O139 surface polysaccharide.     

Characteristics of polyamine stimulation of cyclic nucleotide-independent protein kinase reactions.

Coupled oxidation of octaethylhaemin and phenylhydrazine hydrochloride with 16,16O2 and 18,18O2 produced octaethyl[16O]verdohaemochrome and octaethyl[18O]-verdohaemochrome respectively. Reactions of these products with 16,16O2 in the presence of phenylhydrazine hydrochloride yielded octaethyl[16O, 16O]biliverdin and octaethyl[18O, 16O]biliverdin. The same reactions with 18,18O2 yielded octaethyl[16O, 18O]biliverdin and octaethyl[18O, 18O]biliverdin. Accordingly, the two oxygen atoms of biliverdin are incorporated from different O2 molecules in separate reactions, namely the formation of verdohaemochrome and the conversion of verdohaemochrome into biliverdin. These reactions account for a "two-molecule mechanism' of biliverdin formation from haem with verdohaemochrome participating as an intermediate product.     

The genes responsible for O-antigen synthesis of vibrio cholerae O139 are closely related to those of vibrio cholerae O22.

Several studies have shown that the emergence of the O139 serogroup of Vibrio cholerae is a result of horizontal gene transfer of a fragment of DNA from a serogroup other than O1 into the region responsible for O-antigen biosynthesis of the seventh pandemic V. cholerae O1 biotype El Tor strain. In this study, we show that the gene cluster responsible for O-antigen biosynthesis of the O139 serogroup of V. cholerae is closely related to those of O22. When DNA fragments derived from O139 O-antigen biosynthesis gene region were used as probes, the entire O139 O-antigen biosynthesis gene region could be divided into five classes, designated as I-V based on the reactivity pattern of the probes against reference strains of V. cholerae representing serogroups O1-O193. Class IV was specific to O139 serogroup, while classes I-III and class V were homologous to varying extents to some of the non-O1, non-O139 serogroups. Interestingly, the regions other than class IV were also conserved in the O22 serogroup. Long and accurate PCR was employed to determine if a simple deletion or substitution was involved to account for the difference in class IV between O139 and O22. A product of approx. 15kb was amplified when O139 DNA was used as the template, while a product of approx. 12.5kb was amplified when O22 DNA was used as the template, indicating that substitution but not deletion could account for the difference in the region between O22 and O139 serogroups. In order to precisely compare between the genes responsible for O-antigen biosynthesis of O139 and O22, the region responsible for O-antigen biosynthesis of O22 serogroup was cloned and analyzed. In concurrence with the results of the hybridization test, all regions were well conserved in O22 and O139 serogroups, although wbfA and the five or six genes comprising class IV in O22 and O139 serogroups, respectively, were exceptions. Again the genes in class IV in O22 were confirmed to be specific to O22 among the 155 'O' serogroups of V. cholerae. These data suggest that the gene clusters responsible for O139 O-antigen biosynthesis are most similar to those of O22 and genes within class IV of O139, and O22 defines the unique O antigen of O139 or O22.     

Prevalence of Pseudomonas aeruginosa O serogroups

The serological typing of 708 P. aeruginosa strains made it possible to determine serogroups in 97.9% of cultures. Serogroups O2 and O6 were the most prevalent (33.8% and 2.5% respectively); serotypes O1, O3 and O11 also occurred rather frequently (about 10%); O4, O7 and O9 were rare (3-8%), serotypes O10 and O12, very rare (less than 1%). The prevalence of P. aeruginosa strains O2 and O6 among the clinical strains was shown over a period of 10 years, serogroup O2 always playing the leading role. In serogroups, the predominance of strains with a definite combination of partial antigen was established; strains with the antigenic structure not described in the International Scheme of the Structure of O-Antigens were detected.     

NOR regions of polychaete worms of the genus Ophryotrocha studied by chromosome banding techniques and FISH

This article reports the results of cytogenetic analyses carried out on 10 species of polychaete worms belonging to the genus Ophryotrocha (Dorvilleidae). Nucleolar organizer regions (NORs) were characterized by Ag staining, C-banding, CMA3 staining, and ribosomal fluorescent in situ hybridization (rDNA FISH). Extensive intraspecific variation in NOR number and distribution were observed in O. costlowi, O. sp. macrovifera, O. notoglandulata, O.l. labronica, O. l. pacifica (2n = 6), O. p. puerilis, O. diadema (2n = 8), O. hartmanni, O. gracilis (2n = 10). In O. sp. robusta (2n = 10), Ag-NORs were always located on a single chromosome pair. CMA3 staining suggests a possible trend toward a GC-rich rDNA compartmentalization. In O.l. labronica, O. p. puerilis, O. diadema, and O. sp. robusta rDNA FISH shows that Ag and FISH signals coincide. Results from C-banding seem to indicate that the increased genome size (GS) observed in O. sp. macrovifera (0.8 pg) and O. hartmanni (1.16 pg) compared to the base GS value of the genus (0.4 pg) cannot be attributed to variation in the heterochromatin content.     

Adequacy of tissue oxygenation in intact dog intestine

Changes in O2 consumption, O2 extraction, and intramural pH, resulting from a decreasing O2 delivery, were studied in the intact dog intestine. The O2 delivery was decreased by ischemia, hypoxia, and combined hypoxia-ischemia. A noninvasive approach for determining intramural pH based on the principle of tonometry was used. There was a strong correlation between the changes in intramural pH and intestinal O2 consumption as O2 delivery was decreased. Intramural pH and O2 consumption were initially maintained in the face of decreasing O2 delivery, but after a critical point they decreased. This critical point was 60.3 +/- 1.6% of base-line O2 delivery in the ischemic group and 51.3 +/- 2.7% of base line in the hypoxic-ischemic group. Despite a decrease to 36.0 +/- 5.6% of base-line O2 delivery, the intramural pH and O2 consumption did not decrease in the hypoxic group. O2 extraction increased with decreasing O2 delivery but did not plateau, indicating no diffusion limitation. The data suggest that blood flow is the major factor limiting intestinal O2 consumption. It is concluded that the noninvasive measure of intramural pH is a good marker of the adequacy of tissue oxygenation in canine intestine.     

Radiation sensitization of E. coli B/r by mixtures of oxygen and nitrous oxide

Oxygen (O2) sensitizes bacterial cells in at least two mechanistically different ways, depending on the specific O2 concentration present during irradiation. Based on previous work from this laboratory, it has been proposed that nitrous oxide (N2O) and low concentrations of O2 share a common mechanism for damage. This mechanism, involving the production of superoxide anion radicals (O2-), is different from that which causes damage at high O2 concentrations. Others, however, have presented evidence that N2O and O2 (usually tested only at high concentrations) act in different ways to sensitize bacterial cells. We have now measured the radiation sensitivity in mixtures of N2O and O2 to observe additivity patterns and to determine if these two agents have any common processes for sensitization. We found that some low O2 concentrations do not increase the response in N2O, although they can have significant sensitizing effects in N2. This lack of additivity is taken as evidence for a common mechanism of damage from N2O and low concentrations of O2. In contrast, damage from high concentrations of O2 is additive to the damage from N2O. The greatest sensitivity, observed with a gas mixture of about 15 per cent O2/85 per cent N2O, is equivalent to the response in 100 per cent N2 plus the maximum amount of damage O2 can cause plus the maximum amount of damage N2O can cause. This additivity is taken as evidence that N2O and high concentrations of O2 sensitize in different ways. Thus, O2 is known to sensitize these bacteria in at least two different ways; one of these is apparently also the way N2O sensitizes.     

金粉蕨属的分子系统学研究——基于5种叶绿体DNA序列片段

金粉蕨属（Onychium Kaulfuss）隶属广义凤尾蕨科中的凤尾蕨亚科。迄今为止,该属属下分组及种间界定等仍有诸多问题亟待解决。本研究选取5个叶绿体DNA 序列片段 （rbcL/atpA/matK/trnL-trnF/trnG-trnR）,采用最大似然法（ML）和贝叶斯法（BI）构建金粉蕨属的系统发育树。结果表明：（1）金粉蕨属的9个成员被分置于两大支上。其中野雉尾金粉蕨（Onychium japonicum(Thunberg) Kunze）、西藏金粉蕨（O.tibeticum Ching & S.K.Wu）、木坪金粉蕨（O.moupinense Ching）、湖北金粉蕨（O.moupinense var. ipii(Ching) K.H.Shing）、栗柄金粉蕨（O.japonicum var. lucidum(D.Don) Christ）、黑足金粉蕨（O.cryptogrammoides Christ）、繁羽金粉蕨（O.plumosum Ching）聚为一支;而金粉蕨（O.siliculosum(Desvaux) C.Christensen）和蚀盖金粉蕨（O.tenuifrons Ching）则聚为另一支,可为该属的属下分组提供分子系统学证据;（2）野雉尾金粉蕨与栗柄金粉蕨在系统树中并没有聚在一起,而是被其它类群分割开来,不支持将后者作为野雉尾金粉蕨的变种,建议将栗柄金粉蕨提升为种的等级;（3）系统树上木坪金粉蕨与湖北金粉蕨的样本聚在一个细支上,支持《中国植物志》将湖北金粉蕨作为木坪金粉蕨变种的分类处理;（4）西藏金粉蕨与野雉尾金粉蕨聚在一起,并得到较高的支持,说明两者的关系近缘。     

Characterization of the DNA binding domain of bacteriophage lambda O protein

The lambda O and P gene products are required for the initiation of lambda DNA replication. In order to study the biochemistry of this process, we have constructed plasmids that carry the lambda O gene, P gene, and half of the O gene coding for the amino-terminal half of the O protein. Each is under the control of the inducible lambda promoter, PL. We have purified these three proteins from induced cells carrying the plasmids. Our results show that the amino-terminal portion of the O protein binds to the lambda origin of replication in a manner similar to the intact lambda O protein, demonstrating that the amino-terminal portion of O protein contains the DNA binding domain. Using chromatographic procedures, we have isolated a complex of lambda O and P proteins with lambda dv DNA. The amino-terminal portion of the O protein does not complex with P protein under the same conditions. This suggests that the specificity of the lambda O protein for P protein resides in the carboxyl-terminal half of the lambda O protein. Our results also show that, while the intact O protein is active in in vitro replication of lambda dv plasmid DNA, the amino-terminal portion of the O protein is inactive and is a competitive inhibitor of the lambda O protein in this reaction. These results confirm previous genetic observations that were interpreted as indicating a bifunctional structure for the lambda O protein with the amino-terminal domain recognizing the lambda origin of replication and the carboxyl-terminal domain interacting with the lambda P protein.     

A review of the Ompok hypophthalmus group of silurid catfishes with the description of a new species from South-East Asia

The identities of the nominal species in the Ompok hypophthalmus group of silurid catfishes, namely Ompok hypophthalmus , O. macronema and O. urbaini are verified in this study. Ompok macronema is hypothesized to be a junior synonym of O. hypophthalmus , and O. urbaini (previously considered a junior synonym of O. hypophthalmus ) is hypothesized to be valid, distinct species. Ompok hypophthalmus is restricted to Java and the Barito River drainage in southern Borneo, and the material previously identified as O. hypophthalmus from Sumatra, the Malay Peninsula and Borneo represents O. rhadinurus , a new species.     

Presence of virulence and fitness gene modules of enterohemorrhagic Escherichia coli in atypical enteropathogenic Escherichia coli O26

Enterohemorrhagic Escherichia coli (EHEC) strains of serogroup O26 cause hemolytic-uremic syndrome (HUS) whereas atypical enteropathogenic E. coli (aEPEC) O26 typically cause uncomplicated diarrhea but have been also isolated from HUS patients. To gain insight into the virulence of aEPEC O26, we compared the presence of O island (OI) 122, which is associated with enhanced virulence in EHEC strains, among aEPEC O26 and EHEC O26 clinical isolates. We also tested these strains for the high pathogenicity island (HPI) which is a fitness island. All 20 aEPEC O26 and 20 EHEC O26 investigated contained virulence genes located within OI-122 (efa1/lifA, nleB, nleE, ent). In both aEPEC O26 and EHEC O26, OI-122 was linked to the locus for enterocyte effacement, forming a mosaic island which was integrated in pheU. Moreover, strains of these two pathotypes shared a conserved HPI. These data support a close relatedness between aEPEC O26 and EHEC O26 and have evolutionary implications. The presence of OI-122 in aEPEC O26 might contribute to their pathogenic potential.     

Superoxide peroxidase activity of ovoperoxidase, the cross-linking enzyme of fertilization

Ovoperoxidase, an enzyme secreted by the eggs of the sea urchin Stronglycocentrotus purpuratus upon activation, catalyzes the formation of dityrosine residues in the fertilization envelope. This cross-linking reaction requires extracellular H2O2, which is produced by the egg during the cyanide-insensitive "respiratory burst" of fertilization. While investigating the possibility that the sea urchin oxidase might generate O2- as a precursor to H2O2, we discovered that ovoperoxidase possessed O2- degrading activity. Ovoperoxidase catalyzed the breakdown of O2- in a reaction that was sensitive to inhibition by catalase, indicating a requirement for H2O2. High concentrations of either O2- or H2O2 inhibited the O2- degrading activity of ovoperoxidase, as did the peroxidase inhibitors aminotriazole, azide, and phenylhydrazine. When ovoperoxidase was heated at 56 degrees C, it lost O2- degrading activity in parallel with peroxidase activity. In contrast, the copper-chelating agent diethyldithiocarbamate, which completely inactivated CuZn superoxide dismutase, failed to affect ovoperoxidase. The requirement for H2O2 and the inhibition by aminotriazole, azide, and phenylhydrazine support the hypothesis that ovoperoxidase catalyzes the breakdown of O2- by a peroxidative mechanism. Ovoperoxidase may play a role in protecting the developing embryo from oxidants derived from O2-.     

Production of cytolethal distending toxin and other virulence characteristics of Escherichia coli strains of serogroup O86

Genetic and phenotypic virulence markers of different categories of diarrhoeagenic Escherichia coli were investigated in 106 strains of enteropathogenic E. coli (EPEC) serogroup O86. The most frequent serotype found was O86:H34 (86%). Strains of this serotype and the non motile ones behaved as EPEC i.e., carried eae, bfpA and EAF DNA sequences and presented localised adherence to HeLa cells. Serotypes O86:H2, O86:H6, O86:H10, O86:H18, O86:H27 and O86:H non determined, belonged to other categories. The majority of the strains of serotype O86:H34 and non motile strains produced cytolethal-distending toxin (CDT). The ribotyping analysis showed a correlation among ribotypes, virulence markers and serotypes, thus suggesting that CDT production might be a property associated with a universal clone represented by the O86:H34 serotype.     

Electrophoretic identification and phylogenetic relationships of indigenous tilapiine species of Zimbabwe

In order to characterize Zimbabwean tilapias 34 populations of seven species, two in the genus Tilapia and five in Oreochromis , were analysed using horizontal starch gel electrophoresis. Twenty-seven loci were polymorphic while five were monomorphic but had fixed allelic differences among some species and six were monomorphic for the same allele in all species. No fixed allelic differences were found between O. mossambicus and O.mortimeri , and only one locus distinguished O. andersonii from O. mossambicus and O. mortimeri . Pairwise comparisons of O. mossambicus or O. mortimeri populations of genetic distances frequently showed a greater degree of difference within the species than was evident in some O. mossambicus O. mortimeri pairs. This study failed to distinguish O. mortimeri as a distinct species from O. mossambicus . The Tilapia species formed distinct clusters from Oreochromis in both consensus eighbourjoining and distance Wagner topologies. Oreochromis ossambicus, O. mortimeri and O. andersonii clustered together consistently. Although some differences from the taxonomic arrangement of Trewavas are discussed, the principal relationships revealed in our analysis are consistent with most recent studies.     

Loss of N2O reductase activity as an explanation for poor growth of Pseudomonas aeruginosa on N2O

N2O uptake activity of cells and N2O reductase activity of the soluble fraction from denitrifying bacteria were assayed. Pseudomonas aeruginosa strains PAO1 and P1 lost most of their N2O uptake activity and the ability to grow well on N2O within 2 to 5 h after exposure to N2O. Extensive loss of N2O reductase activity accompanied the nearly complete loss of N2O uptake activity under N2O. Paracoccus denitrificans retained much, but not all, of both activities and the ability to grow vigorously on N2O. The pattern with P. aeruginosa strain P2 resembled that for PAO1 and P1 except that loss of the activities proceeded at a slower rate and growth could continue for up to 12 h after exposure to N2O. The inability of a number of P. aeruginosa strains to grow well on N2O is therefore a direct consequence of the nearly complete loss of N2O reductase activity. Turnover-dependent inactivation of N2O reductase and its reactivation under reducing conditions occurred in vitro for the enzyme from P. aeruginosa and Paracoccus denitrificans. These events may be significant in determining the activity level of N2O reductase in denitrifying bacteria during N2O respiration.     

Genetic analysis of the Cronobacter sakazakii O4 to O7 O-antigen gene clusters and development of a PCR assay for identification of all C. sakazakii O serotypes

The Gram-negative bacterium Cronobacter sakazakii is an emerging food-borne pathogen that causes severe invasive infections in neonates. Variation in the O-antigen lipopolysaccharide in the outer membrane provides the basis for Gram-negative bacteria serotyping. The O-antigen serotyping scheme for C. sakazakii, which includes seven serotypes (O1 to O7), has been recently established, and the O-antigen gene clusters and specific primers for three C. sakazakii serotypes (O1, O2, and O3) have been characterized. In this study, the C. sakazakii O4, O5, O6, and O7 O-antigen gene clusters were sequenced, and gene functions were predicted on the basis of homology. C. sakazakii O4 shared a similar O-antigen gene cluster with Escherichia coli O103. The general features and anomalies of all seven C. sakazakii O-antigen gene clusters were evaluated and the relationship between O-antigen structures and their gene clusters were investigated. Serotype-specific genes for O4 to O7 were identified, and a molecular serotyping method for all C. sakazakii O serotypes, a multiplex PCR assay, was developed by screening against 136 strains of C. sakazakii and closely related species. The sensitivity of PCR-based serotyping method was determined to be 0.01 ng of genomic DNA and 10(3) CFU of each strain/ml. This study completes the elucidation of C. sakazakii O-antigen genetics and provides a molecular method suitable for the identification of C. sakazakii O1 to O7 strains.     

Phylogenetic analysis of Oryza rufipogon strains and their relations to Oryza sativa strains by insertion polymorphism of rice SINEs

Oryza rufipogon, the progenitor of the cultivated rice species Oryza sativa, is known by its wide intraspecific variation. In this study, we performed phylogenetic analyses of O. rufipogon strains and their relationships to O. sativa strains by using 26 newly identified p-SINE1 members from O. rufipogon strains, in addition to 23 members previously identified from O. sativa strains. A total of 103 strains of O. rufipogon and O. sativa were examined for the presence and absence of each of the p-SINE1 members at respective loci by PCR with a pair of primers that hybridize to the regions flanking each p-SINE1 member. A phylogenetic tree constructed on the basis of the insertion polymorphism of p-SINE1 members showed that O. rufipogon and O. sativa strains are classified into three groups. The first group consisted of O. rufipogon perennial strains mostly from China and O. sativa ssp. japonica strains, which included javanica strains forming a distinct subgroup. The second group consisted of almost all the O. rufipogon annual strains, a few O. rufipogon perennial strains and O. sativa ssp. indica strains. These groupings, in addition to other results, support the previous notion that annual O. rufipogon originated in the O. rufipogon perennial population, and that O. sativa originated polyphyletically in the O. rufipogon populations. The third group consisted of the other perennial strains and intermediate-type strains of O. rufipogon, in which the intermediate-type strains are most closely related to a hypothetical ancestor with no p-SINE1 members at the respective loci and to those belonging to the other rice species with the AA genome. This suggests that O. rufipogon perennial strains are likely to have originated from the O. rufipogon intermediate-ecotype population.