bluuebunny/crossref_metadata_2025_split huggingface dataset:
Polarization of the Immune Response to the Single Immunodominant Epitope of p38, a MajorSchistosoma mansoniEgg Antigen, Generates Th1- or Th2-Type Cytokines and Granulomas
Authors: Chen Yiguang , Boros Dov L. 
Published: December 2019

ABSTRACTIn schistosomiasis mansoni, helminth eggs secrete soluble egg antigens (SEA) that induce T-cell-mediated granulomatous tissue responses. The cloned 38-kDa peptide (p38) of SEA was shown to induce and elicit Th1-type responsiveness inH-2kmice. Subsequently, the immunodominant T-cell epitope (P4) of p38 was shown to elicit pulmonary granuloma formation and Th1-type cytokine production in sensitized or infected mice. Here, we report that the immune response to p38 or P4 can be polarized to a Th1 or Th2 profile when the peptides are presented intraperitoneally in soluble recombinant interleukin-12 (IL-12) or alum adjuvant, respectively. The Th1 or Th2 profile was verified by cytokine secretion, enzyme-linked spot assay, and antibody isotype characterization. Importantly, the polarized immune response generated two types of pulmonary granulomas around injected P4-coated beads. The type 1 granulomas were smaller and contained mononuclear cells and occasional thin strands of deposited collagen. In contrast, the type 2 lesions were larger and contained mononuclear cells, large numbers of eosinophils, and several thick bands of deposited collagen. By reverse transcription-PCR cytokine, message in the type 1 granuloma-bearing lungs was found for gamma interferon, tumor necrosis factor alpha, and inducible nitric oxide synthase but not for IL-4 or IL-5. Conversely, lungs with type 2 granulomas had message only for IL-4 and IL-5. These results show that in the proper cytokine environment, the response to a strong Th1 inducer peptide can be deviated to a Th2 profile.
Pure Botulinum Neurotoxin Is Absorbed from the Stomach and Small Intestine and Produces Peripheral Neuromuscular Blockade
Authors: Maksymowych Andrew B. , Reinhard Marco , Malizio Carl J. , Goodnough Michael C. , Johnson Eric A. , Simpson Lance L. 
Published: December 2019

ABSTRACT

Clostridium botulinum
serotype A produces a neurotoxin composed of a 100-kDa heavy chain and a 50-kDa light chain linked by a disulfide bond. This neurotoxin is part of a ca. 900-kDa complex, formed by noncovalent association with a single nontoxin, nonhemagglutinin subunit and a family of hemagglutinating proteins. Previous work has suggested, although never conclusively demonstrated, that neurotoxin alone cannot survive passage through the stomach and/or cannot be absorbed from the gut without the involvement of auxiliary proteins in the complex. Therefore, this study compared the relative absorption and toxicity of three preparations of neurotoxin in an in vivo mouse model. Equimolar amounts of serotype A complex with hemagglutinins, complex without hemagglutinins, and purified neurotoxin were surgically introduced into the stomach or into the small intestine. In some experiments, movement of neurotoxin from the site of administration was restricted by ligation of the pylorus. Comparison of relative toxicities demonstrated that at adequate doses, complex with hemagglutinins, complex without hemagglutinins, and pure neurotoxin can be absorbed from the stomach. The potency of neurotoxin in complex was greater than that of pure neurotoxin, but the magnitude of this difference diminished as the dosage of neurotoxin increased. Qualitatively similar results were obtained when complex with hemagglutinins, complex without hemagglutinins, and pure neurotoxin were placed directly into the intestine. This work establishes that pure botulinum neurotoxin serotype A is toxic when administered orally. This means that pure neurotoxin does not require hemagglutinins or other auxiliary proteins for absorption from the gastrointestinal system into the general circulation.
Identification of Abundantly Expressed Novel and Conserved Genes from the Infective Larval Stage ofToxocara canisby an Expressed Sequence Tag Strategy
Authors: Tetteh Kevin K. A. , Loukas Alex , Tripp Cindy , Maizels Rick M. 
Published: December 2019

ABSTRACTLarvae ofToxocara canis, a nematode parasite of dogs, infect humans, causing visceral and ocular larva migrans. In noncanid hosts, larvae neither grow nor differentiate but endure in a state of arrested development. Reasoning that parasite protein production is orientated to immune evasion, we undertook a random sequencing project from a larval cDNA library to characterize the most highly expressed transcripts. In all, 266 clones were sequenced, most from both 3′ and 5′ ends, and similarity searches against GenBank protein and dbEST nucleotide databases were conducted. Cluster analyses showed that 128 distinct gene products had been found, all but 3 of which represented newly identified genes. Ninety-five genes were represented by a single clone, but seven transcripts were present at high frequencies, each composing >2% of all clones sequenced. These high-abundance transcripts include a mucin and a C-type lectin, which are both major excretory-secretory antigens released by parasites. Four highly expressed novel gene transcripts, termedant(abundant novel transcript) genes, were found. Together, these four genes comprised 18% of all cDNA clones isolated, but no similar sequences occur in theCaenorhabditis elegansgenome. While the coding regions of the four genes are dissimilar, their 3′ untranslated tracts have significant homology in nucleotide sequence. The discovery of these abundant, parasite-specific genes of newly identified lectins and mucins, as well as a range of conserved and novel proteins, provides defined candidates for future analysis of the molecular basis of immune evasion byT. canis.
Molecular Cloning and Characterization of Rat Genes Encoding Homologues of Human β-Defensins
Authors: Jia Hong Peng , Mills Jesse N. , Barahmand-Pour Fariba , Nishimura Darryl , Mallampali Rama K. , Wang Guoshun , Wiles Kerry , Tack Brian F. , Bevins Charles L. , McCray Paul B. 
Published: December 2019

ABSTRACT
β-Defensins are cationic peptides with broad-spectrum antimicrobial activity that may play a role in mucosal defenses of several organs. They have been isolated in several species, and in humans, two β-defensins have been identified. Here, we report the identification of two genes encoding β-defensin homologues in the rat. Partial cDNAs were found by searching the expressed-sequence-tag database, and primers were designed to generate full-length mRNA coding sequences. One gene was highly similar to the human β-defensin-1 (HBD-1) gene and mouse β-defensin-1 gene at both the nucleic acid and amino acid levels and was termed rat β-defensin-1 (RBD-1). The other gene, named RBD-2, was homologous to the HBD-2 and bovine tracheal antimicrobial peptide (TAP) genes. The predicted prepropeptides were strongly cationic, were 69 and 63 residues in length for RBD-1 and RBD-2, respectively, and contained the six-cysteine motif characteristic of β-defensins. The β-defensin genes mapped closely on rat chromosome 16 and were closely linked to the α-defensins genes, suggesting that they are part of a gene cluster, similar to the organization reported for humans. Northern blot analysis showed that both RBD-1 and RBD-2 mRNA transcripts were ∼0.5 kb in length; RBD-1 mRNA was abundantly transcribed in the rat kidney, while RBD-2 was prevalent in the lung. Reverse transcription-PCR indicated that RBD-1 and RBD-2 mRNAs were distributed in a variety of other tissues. In the lung, RBD-1 mRNA expression localized to the tracheal epithelium while RBD-2 was expressed in alveolar type II cells. In conclusion, we characterized two novel β-defensin homologues in the rat. The rat may be a useful model to investigate the function and contribution of β-defensins to host defense in the lung, kidney, and other tissues.
Inhibitory Effects of Protamines on Proteolytic and Adhesive Activities of
Porphyromonas gingivalis
Authors: Kontani Masanori , Amano Atsuo , Nakamura Takayuki , Nakagawa Ichiro , Kawabata Shigetada , Hamada Shigeyuki 
Published: December 2019

ABSTRACT

Protamines (salmine prepared from sperm DNA of salmon and clupeine from herring sperm), which are basic peptides rich in arginine, were found to inhibit the proteolytic activity of arginine-specific cysteine protease (RC-protease) from
Porphyromonas gingivalis
. Lineweaver-Burk plot analysis revealed that the protamines competitively inhibited proteolytic activity with cleavage of benzoyl-
l
-arginine-
p
-nitroanilide, a synthetic substrate of RC-protease. Furthermore, the protamines were capable of binding strongly to
P. gingivalis
fimbriae and inhibited fimbrial interaction with immobilized fibronectin. These results clearly show that protamines are potent inhibitors of the proteolytic and adhesive activities of
P. gingivalis.
Bactericidal and Cross-Protective Activities of a Monoclonal Antibody Directed againstNeisseria meningitidisNspA Outer Membrane Protein
Authors: Cadieux Nathalie , Plante Martin , Rioux Clément R. , Hamel Josée , Brodeur Bernard R. , Martin Denis 
Published: December 2019

ABSTRACTThe cross-bactericidal and cross-protective activities of a monoclonal antibody (MAb) named Me-7, which is directed against an antigenically highly conserved epitope on the meningococcal NspA protein, were studied. This MAb efficiently killed in vitro, in the presence of rabbit or human serum, 13 of 14 meningococcal strains tested, including 9 of 9, 2 of 3, and 2 of 2 strains of serotypes B, A, and C, respectively. MAb Me-7 also significantly reduced by more than 75% the levels of bacteremia recorded for mice challenged with 10 of 11 meningococcal strains tested. Analysis of the predicted amino acid sequence of the NspA protein from the meningococcal strain MCH88 (A:4:P1.10), which was not killed by MAb Me-7, indicated the presence of an additional glutamine residue at position 73, compared to the three other NspA sequences. The data presented in this study suggest that antibodies directed against this highly conserved outer membrane protein could protect against meningococcal infections.
Experimental Transmission ofNeisseria gonorrhoeaefrom Pregnant Rat to Fetus
Authors: Nowicki Stella , Selvarangan Rangaraj , Anderson Garland 
Published: December 2019

ABSTRACTSprague-Dawley rats were infected on day 20 of pregnancy by intraperitoneal inoculation withNeisseria gonorrhoeae. Disseminated gonococcal infection (DGI) and pelvic inflammatory disease (PID) strains in the presence of C1q but not in the presence of bovine serum albumin (BSA) were able to spread from the pregnant rat to the fetus and resulted in fetal mortality. Transmission of DGI and PID strains that are serum resistant (serr) andsac-4positive but not of a local infection strain that is sersandsac-4negative was facilitated by the C1q-dependent mechanism. This study provides the first experimental model that may mimic the transmission of gonococcal infection from mother to the fetus during pregnancy.
Defects in Assembly of the Extracellular Matrix Are Responsible for Altered Morphogenesis of a
Candida albicans phr1
Mutant
Authors: Popolo Laura , Vai Marina 
Published: December 2019

ABSTRACT

Analysis of
Candida albicans
cells using antibodies directed against Gas1p/Ggp1p,
Saccharomyces cerevisiae
homolog of Phr1p, revealed that Phr1p is a glycoprotein of about 88 kDa whose accumulation increases with the rise of external pH. This polypeptide is present both in the yeast form and during germ tube induction. In the Phr1
−
cells at pH 8 the solubility of glucans in alkali is greatly affected. In the parental strain the alkali-soluble/-insoluble glucan ratio shows a 50% decrease at pH 8 with respect to pH 4.5, whereas in the null mutant it is unchanged, indicating the lack of a polymer cross-linker activity induced by the rise of pH. The mutant has a sixfold increase in chitin level and is hypersensitive to calcofluor. Consistently with a role of chitin in strengthening the cell wall, Phr1
−
cells are more sensitive to nikkomycin Z than the parental strain.
Stability of the
Escherichia coli
Division Inhibitor Protein MinC Requires Determinants in the Carboxy-Terminal Region of the Protein
Authors: Sen Mita , Rothfield Lawrence I. 
Published: December 2019

ABSTRACT

Certain mutations in the C-terminal region of the
Escherichia coli
division inhibitor protein MinC cause loss of function of the division inhibitor by making MinC more sensitive to degradation by Lon protease, implying a possible role for the C-terminal region in regulating the stability and cellular concentration of MinC.
Molecular Characterization of IS
1541
Insertions in the Genome of
Yersinia pestis
Authors: Odaert Monique , Devalckenaere Annie , Trieu-Cuot Patrick , Simonet Michel 
Published: December 2019

ABSTRACT

The genome of
Yersinia pestis
, the causative agent of plague, contains at least 30 copies of an element, designated IS
1541
, which is structurally related to IS
200
(85% identity). One such element is inserted within the chromosomal
inv
gene (M. Simonet, B. Riot, N. Fortineau, and P. Berche, Infect. Immun. 64:375–379, 1996). We characterized other IS
1541
insertions by cloning 14 different
Y. pestis
6/69M loci carrying a single copy of this insertion sequence (IS) into
Escherichia coli
and, for each element, sequencing 250 bp of both flanking regions. In no case was this IS element inserted into large open reading frames; however, in eight cases, it was detected downstream (17 to 139 bp) of genes thought to be transcribed monocistronically or which constituted the last gene of an operon, and in only one case was it detected upstream (37 bp) of the first gene of an operon. Sequence analysis revealed stem-loop structures (Δ
G
, <−10 kcal) resembling rho-independent transcription terminators in 8 of the 14 insertion sites. These motifs might constitute hot spots for insertion of this IS
1541
element within the
Y. pestis
genome.
RimM and RbfA Are Essential for Efficient Processing of 16S rRNA in
Escherichia coli
Authors: Bylund Göran O. , Wipemo L. Charlotta , Lundberg L. A. Carina , Wikström P. Mikael 
Published: December 2019

ABSTRACT

The
trmD
operon is located at 56.7 min on the genetic map of the
Escherichia coli
chromosome and contains the genes for ribosomal protein (r-protein) S16, a 21-kDa protein (RimM, formerly called 21K), the tRNA (m
1
G37)methyltransferase (TrmD), and r-protein L19, in that order. Previously, we have shown that strains from which the
rimM
gene has been deleted have a sevenfold-reduced growth rate and a reduced translational efficiency. The slow growth and translational deficiency were found to be partly suppressed by mutations in
rpsM
, which encodes r-protein S13. Further, the RimM protein was shown to have affinity for free ribosomal 30S subunits but not for 30S subunits in the 70S ribosomes. Here we have isolated several new suppressor mutations, most of which seem to be located close to or within the
nusA
operon at 68.9 min on the chromosome. For at least one of these mutations, increased expression of the ribosome binding factor RbfA is responsible for the suppression of the slow growth and translational deficiency of a Δ
rimM
mutant. Further, the RimM and RbfA proteins were found to be essential for efficient processing of 16S rRNA.
Molecular and Genetic Analysis of Two Closely Linked Genes That Encode, Respectively, a Protein Phosphatase 1/2A/2B Homolog and a Protein Kinase Homolog in the Cyanobacterium
Anabaena
sp. Strain PCC 7120
Authors: Zhang Cheng-Cai , Friry Aline , Peng Ling 
Published: December 2019

ABSTRACT

Reversible protein phosphorylation plays important roles in signal transduction. One gene,
prpA
, encoding a protein similar to eukaryotic types of phosphoprotein phosphatases PP1, PP2A, and PP2B, was cloned from the nitrogen-fixing cyanobacterium
Anabaena
sp. strain PCC 7120. Interestingly, a eukaryotic-type protein kinase gene,
pknE
, was found 301 bp downstream of
prpA
. This unusual genetic arrangement provides the opportunity for study about how the balance between protein phosphorylation and dephosphorylation can regulate cellular activities. Both proteins were overproduced in
Escherichia coli
and used to raise polyclonal antibodies. Immunodetection and RNA/DNA hybridization experiments suggest that these two genes are unlikely to be coexpressed, despite their close genetic linkage. PrpA is expressed constitutively under different nitrogen conditions, while PknE expression varies according to the nature of the nitrogen source. Inactivation analysis in vivo suggests that PrpA and PknE function to ensure a correct level of phosphorylation of the targets in order to regulate similar biological processes such as heterocyst structure formation and nitrogen fixation.
The
l
-Isoaspartyl Protein Repair Methyltransferase Enhances Survival of Aging
Escherichia coli
Subjected to Secondary Environmental Stresses
Authors: Visick Jonathan E. , Cai Hui , Clarke Steven 
Published: December 2019

ABSTRACT

Like its homologs throughout the biological world, the
l
-isoaspartyl protein repair methyltransferase of
Escherichia coli
, encoded by the
pcm
gene, can convert abnormal
l
-isoaspartyl residues in proteins (which form spontaneously from asparaginyl or aspartyl residues) to normal aspartyl residues. Mutations in
pcm
were reported to greatly reduce survival in stationary phase and when cells were subjected to heat or osmotic stresses (C. Li and S. Clarke, Proc. Natl. Acad. Sci. USA 89:9885–9889, 1992). However, we subsequently demonstrated that those strains had a secondary mutation in
rpoS
, which encodes a stationary-phase-specific sigma factor (J. E. Visick and S. Clarke, J. Bacteriol. 179:4158–4163, 1997). We now show that the
rpoS
mutation, resulting in a 90% decrease in HPII catalase activity, can account for the previously observed phenotypes. We further demonstrate that a new
pcm
mutant lacks these phenotypes. Interestingly, the newly constructed
pcm
mutant, when maintained in stationary phase for extended periods, is susceptible to environmental stresses, including exposure to methanol, oxygen radical generation by paraquat, high salt concentrations, and repeated heating to 42°C. The
pcm
mutation also results in a competitive disadvantage in stationary-phase cells. All of these phenotypes can be complemented by a functional
pcm
gene integrated elsewhere in the chromosome. These data suggest that protein denaturation and isoaspartyl formation may act synergistically to the detriment of aging
E. coli
and that the repair methyltransferase can play a role in limiting the accumulation of the potentially disruptive isoaspartyl residues in vivo.
An rRNA Fragment and Its Antisense Can Alter Decoding of Genetic Information
Authors: Arkov Alexey L. , Mankin Alexander , Murgola Emanuel J. 
Published: December 2019

ABSTRACT

rRNA plays a central role in protein synthesis and is intimately involved in the initiation, elongation, and termination stages of translation. However, the mode of its participation in these reactions, particularly as to the decoding of genetic information, remains elusive. In this paper, we describe a new approach that allowed us to identify an rRNA segment whose function is likely to be related to translation termination. By screening an expression library of random rRNA fragments, we identified a fragment of the
Escherichia coli
23S rRNA (nucleotides 74 to 136) whose expression caused readthrough of UGA nonsense mutations in certain codon contexts in vivo. The antisense RNA fragment produced a similar effect, but in neither case was readthrough of UAA or UAG observed. Since termination at UGA in
E. coli
specifically requires release factor 2 (RF2), our data suggest that the fragments interfere with RF2-dependent termination.
Penicillin-Binding Protein 1 of
Staphylococcus aureus
Is Essential for Growth
Authors: Wada Akihito , Watanabe Haruo 
Published: December 2019

ABSTRACT

pbpA
, a gene encoding penicillin-binding protein (PBP) 1 of
Staphylococcus aureus
, was cloned in an
Escherichia coli
MC1061 transformant which grew on a plate containing 512 μg of vancomycin per ml. This gene encodes a 744-amino-acid sequence which conserves three motifs of PBPs, SXXK, SXN, and KTG. The chromosomal copy of
pbpA
could be disrupted only when RN4220, a methicillin-sensitive
S. aureus
strain, had additional copies of
pbpA
in its episome. Furthermore, these episomal copies of
pbpA
could not be eliminated by an incompatible plasmid when the chromosomal copy of
pbpA
was disrupted beforehand. Based on these observations, we concluded that
pbpA
is essential for the growth of methicillin-sensitive
S. aureus.
Adaptive Mutagenesis at
ebgR
Is Regulated by PhoPQ
Authors: Hall Barry G. 
Published: December 2019

ABSTRACT

Adaptive mutations are mutations that occur in nondividing or very slowly dividing microbial cells during prolonged nonlethal selection and that are specific to the challenge of the selection in the sense that the only mutations that can be detected are those that provide a growth advantage to the cell. The
phoPQ
genes encode a two-component positively acting regulatory system that controls expression of at least 25 to 30 genes in
Escherichia coli
and
Salmonella typhimurium
. PhoPQ responds to a variety of environmental stress signals including Mg
2+
starvation and nutritional deprivation. Here I show that disruption of
phoP
or
phoQ
by Tn
10
d
C
am significantly reduces the adaptive mutation rate to
ebgR
, indicating that the adaptive mutagenesis machinery is regulated, directly or indirectly, by
phoPQ
. The finding that it is regulated implies that adaptive mutagenesis does not simply result from a failure of various error correction mechanisms during prolonged starvation.
Novel Temperature-Sensitive Mutants of
Escherichia coli
That Are Unable To Grow in the Absence of Wild-Type tRNA
6
Leu
Authors: Nakayashiki Toru , Inokuchi Hachiro 
Published: December 2019

ABSTRACT

Escherichia coli
has only a single copy of a gene for tRNA
6
Leu
(Y. Komine et al., J. Mol. Biol. 212:579–598, 1990). The anticodon of this tRNA is CAA (the wobble position C is modified to
O
2
-methylcytidine), and it recognizes the codon UUG. Since UUG is also recognized by tRNA
4
Leu
, which has UAA (the wobble position U is modified to 5-carboxymethylaminomethyl-
O
2
-methyluridine) as its anticodon, tRNA
6
Leu
is not essential for protein synthesis. The BT63 strain has a mutation in the anticodon of tRNA
6
Leu
with a change from CAA to CUA, which results in the amber suppressor activity of this strain (
supP
, Su
+
6). We isolated 18 temperature-sensitive (ts) mutants of the BT63 strain whose temperature sensitivity was complemented by introduction of the wild-type gene for tRNA
6
Leu
. These tRNA
6
Leu
-requiring mutants were classified into two groups. The 10 group I mutants had a mutation in the
miaA
gene, whose product is involved in a modification of tRNAs that stabilizes codon-anticodon interactions. Overexpression of the gene for tRNA
4
Leu
restored the growth of group I mutants at 42°C. Replacement of the CUG codon with UUG reduced the efficiency of translation in group I mutants. These results suggest that unmodified tRNA
4
Leu
poorly recognizes the UUG codon at 42°C and that the wild-type tRNA
6
Leu
is required for translation in order to maintain cell viability. The mutations in the six group II mutants were complemented by introduction of the
gidA
gene, which may be involved in cell division. The reduced efficiency of translation caused by replacement of the CUG codon with UUG was also observed in group II mutants. The mechanism of requirement for tRNA
6
Leu
remains to be investigated.