bluuebunny/crossref_metadata_2025 huggingface dataset:
New Device for High-Throughput Viability Screening of Flow Biofilms
Authors: Benoit Michael R. , Conant Carolyn G. , Ionescu-Zanetti Cristian , Schwartz Michael , Matin A.
Published: May 2010

Control of biofilms requires rapid methods to identify compounds effective against them and to isolate resistance-compromised mutants for identifying genes involved in enhanced biofilm resistance. While rapid screening methods for microtiter plate well (“static”) biofilms are available, there are no methods for such screening of continuous flow biofilms (“flow biofilms”). Since the latter biofilms more closely approximate natural biofilms, development of a high-throughput (HTP) method for screening them is desirable. We describe here a new method using a device comprised of microfluidic channels and a distributed pneumatic pump (BioFlux) that provides fluid flow to 96 individual biofilms. This device allows fine control of continuous or intermittent fluid flow over a broad range of flow rates, and the use of a standard well plate format provides compatibility with plate readers. We show that use of green fluorescent protein (GFP)-expressing bacteria, staining with propidium iodide, and measurement of fluorescence with a plate reader permit rapid and accurate determination of biofilm viability. The biofilm viability measured with the plate reader agreed with that determined using plate counts, as well as with the results of fluorescence microscope image analysis. Using BioFlux and the plate reader, we were able to rapidly screen the effects of several antimicrobials on the viability of
Pseudomonas aeruginosa
PAO1 flow biofilms.
“CandidatusAnadelfobacter veles” and “CandidatusCyrtobacter comes,” Two NewRickettsialesSpecies Hosted by the Protist CiliateEuplotes harpa(Ciliophora, Spirotrichea)
Authors: Vannini Claudia , Ferrantini Filippo , Schleifer Karl-Heinz , Ludwig Wolfgang , Verni Franco , Petroni Giulio
Published: May 2010

The orderRickettsiales(Alphaproteobacteria) is a well-known group containing obligate endocellular prokaryotes. The order encompasses three families (Rickettsiaceae,Anaplasmataceae, andHolosporaceae) and a fourth, family-level cluster, which includes only one candidate species, “CandidatusMidichloria mitochondrii,” as well as several unnamed bacterial symbionts. The broad host range exhibited by the members of the “CandidatusMidichloria” clade suggests their eventual relevance for a better understanding of the evolution of symbiosis and host specificity ofRickettsiales. In this paper, two new bacteria belonging to the “CandidatusMidichloria” clade, hosted by two different strains of the ciliate protistEuplotes harpa, are described on the basis of ultrastructural observations, comparative 16S rRNA gene sequence analysis, and an estimation of the percentage of infection. Ultrastructure of these bacteria shows some unusual features: one has an electron-dense cytoplasm, and the other one lacks a symbiosomal membrane. The latter was up to now considered an exclusive feature of bacteria belonging to the familyRickettsiaceae. 16S rRNA gene phylogenetic analysis unambiguously places the new bacteria in the “CandidatusMidichloria” clade, although their phylogenetic relationships with other members of the clade are not clearly resolved. This is the first report of a ciliate-borne bacterium belonging to the “CandidatusMidichloria” clade. On the basis of the data obtained, the two bacteria are proposed as two new candidate genera and species, “CandidatusAnadelfobacter veles” and “CandidatusCyrtobacter comes.”
Rotenone Enhances the Antifungal Properties of Staurosporine
Authors: Castro Ana , Lemos Catarina , Falcão Artur , Fernandes Andreia S. , Glass N. Louise , Videira Arnaldo
Published: May 2010

We studied staurosporine-induced cell death in the filamentous fungus
Neurospora crassa
. The generation of reactive oxygen species during the process appears to be an important signaling event, since addition of the antioxidant glutathione prevents the effects of staurosporine on fungal growth. Selected mutants with mutations in respiratory chain complex I are extremely sensitive to the drug, stressing the involvement of complex I in programmed cell death. Following this finding, we determined that the complex I-specific inhibitor rotenone used in combination with staurosporine results in a synergistic and specific antifungal activity, likely through a concerted action on intracellular glutathione depletion. Paradoxically, the synergistic antifungal activity of rotenone and staurosporine is observed in
N. crassa
complex I mutants and in
Saccharomyces cerevisiae
, which lacks complex I. In addition, it is not observed when other complex I inhibitors are used instead of rotenone. These results indicate that the rotenone effect is independent of complex I inhibition. The combination of rotenone and staurosporine is effective against
N. crassa
as well as against the common pathogens
Aspergillus fumigatus
and
Candida albicans
, pointing to its usefulness as an antifungal agent.
Protein Phosphatase 2B (PP2B, Calcineurin) in Paramecium: Partial Characterization Reveals That Two Members of the Unusually Large Catalytic Subunit Family Have Distinct Roles in Calcium-Dependent Processes
Authors: Fraga D. , Sehring I. M. , Kissmehl R. , Reiss M. , Gaines R. , Hinrichsen R. , Plattner H.
Published: May 2010

We characterized the calcineurin (
CaN
) gene family, including the subunits
CaNA
and
CaNB
, based upon sequence information obtained from the
Paramecium
genome project.
Paramecium tetraurelia
has seven subfamilies of the catalytic CaNA subunit and one subfamily of the regulatory CaNB subunit, with each subfamily having two members of considerable identity on the amino acid level (≥55% between subfamilies, ≥94% within CaNA subfamilies, and full identity in the CaNB subfamily). Within CaNA subfamily members, the catalytic domain and the CaNB binding region are highly conserved and molecular modeling revealed a three-dimensional structure almost identical to a human ortholog. At 14 members, the size of the CaNA family is unprecedented, and we hypothesized that the different CaNA subfamily members were not strictly redundant and that at least some fulfill different roles in the cell. This was tested by selecting two phylogenetically distinct members of this large family for posttranscriptional silencing by RNA interference. The two targets resulted in differing effects in exocytosis, calcium dynamics, and backward swimming behavior that supported our hypothesis that the large, highly conserved CaNA family members are not strictly redundant and that at least two members have evolved diverse but overlapping functions. In sum, the occurrence of CaN in
Paramecium
spp., although disputed in the past, has been established on a molecular level. Its role in exocytosis and ciliary beat regulation in a protozoan, as well as in more complex organisms, suggests that these roles for CaN were acquired early in the evolution of this protein family.
ABacillus anthracisS-Layer Homology Protein That Binds Heme and Mediates Heme Delivery to IsdC
Authors: Tarlovsky Yael , Fabian Marian , Solomaha Elena , Honsa Erin , Olson John S. , Maresso Anthony W.
Published: May 2010

The sequestration of iron by mammalian hosts represents a significant obstacle to the establishment of a bacterial infection. In response, pathogenic bacteria have evolved mechanisms to acquire iron from host heme.Bacillus anthracis, the causative agent of anthrax, utilizes secreted hemophores to scavenge heme from host hemoglobin, thereby facilitating iron acquisition from extracellular heme pools and delivery to iron-regulated surface determinant (Isd) proteins covalently attached to the cell wall. However, several Gram-positive pathogens, includingB. anthracis, contain genes that encode near iron transporter (NEAT) proteins that are genomically distant from the genetically linked Isd locus. NEAT domains are protein modules that partake in several functions related to heme transport, including binding heme and hemoglobin. This finding raises interesting questions concerning the relative role of these NEAT proteins, relative to hemophores and the Isd system, in iron uptake. Here, we present evidence that aB. anthracisS-layer homology (SLH) protein harboring a NEAT domain binds and directionally transfers heme to the Isd system via the cell wall protein IsdC. This finding suggests that the Isd system can receive heme from multiple inputs and may reflect an adaptation ofB. anthracisto changing iron reservoirs during an infection. Understanding the mechanism of heme uptake in pathogenic bacteria is important for the development of novel therapeutics to prevent and treat bacterial infections.
Single-Stranded DNA Binding by F TraI Relaxase and Helicase Domains Is Coordinately Regulated
Authors: Dostál Lubomír , Schildbach Joel F.
Published: May 2010

Transfer of conjugative plasmids requires relaxases, proteins that cleave one plasmid strand sequence specifically. The F plasmid relaxase TraI (1,756 amino acids) is also a highly processive DNA helicase. The TraI relaxase activity is located within the N-terminal ∼300 amino acids, while helicase motifs are located in the region comprising positions 990 to 1450. For efficient F transfer, the two activities must be physically linked. The two TraI activities are likely used in different stages of transfer; how the protein regulates the transition between activities is unknown. We examined TraI helicase single-stranded DNA (ssDNA) recognition to complement previous explorations of relaxase ssDNA binding. Here, we show that TraI helicase-associated ssDNA binding is independent of and located N-terminal to all helicase motifs. The helicase-associated site binds ssDNA oligonucleotides with nM-range equilibrium dissociation constants and some sequence specificity. Significantly, we observe an apparent strong negative cooperativity in ssDNA binding between relaxase and helicase-associated sites. We examined three TraI variants having 31-amino-acid insertions in or near the helicase-associated ssDNA binding site. B. A. Traxler and colleagues (J. Bacteriol. 188:6346-6353) showed that under certain conditions, these variants are released from a form of negative regulation, allowing them to facilitate transfer more efficiently than wild-type TraI. We find that these variants display both moderately reduced affinity for ssDNA by their helicase-associated binding sites and a significant reduction in the apparent negative cooperativity of binding, relative to wild-type TraI. These results suggest that the apparent negative cooperativity of binding to the two ssDNA binding sites of TraI serves a major regulatory function in F transfer.
Subcellular Localization and Characterization of the ParAB System fromCorynebacterium glutamicum
Authors: Donovan Catriona , Schwaiger Astrid , Krämer Reinhard , Bramkamp Marc
Published: May 2010

Faithful segregation of chromosomes and plasmids is a vital prerequisite to produce viable and genetically identical progeny. Bacteria use a specialized segregation system composed of the partitioning proteins ParA and ParB to segregate certain plasmids. Strikingly, homologues of ParA and ParB are found to be encoded in many chromosomes. Although mutations in the chromosomal Par system have effects on segregation efficiency, the exact mechanism by which the chromosomes are segregated into the daughter cells is not fully understood. We describe the polar localization of the ParB origin nucleoprotein complex in the actinomyceteCorynebacterium glutamicum. ParB and the origin of replication were found to be stably localized to the cell poles. After replication, the origins move toward the opposite pole. Purified ParB was able to bind to theparSconsensus sequencein vitro.C. glutamicumpossesses two ParA-like partitioning ATPase proteins. Both proteins interact with ParB but show a slightly different subcellular localization and phenotype. While ParA might be part of a conventional partitioning system, PldP seems to play a role in division site selection.
Regulatory System of the Protocatechuate 4,5-Cleavage Pathway Genes Essential for Lignin Downstream Catabolism
Authors: Kamimura Naofumi , Takamura Kazuhiro , Hara Hirofumi , Kasai Daisuke , Natsume Ryo , Senda Toshiya , Katayama Yoshihiro , Fukuda Masao , Masai Eiji
Published: May 2010

Sphingobium
sp. strain SYK-6 converts various lignin-derived biaryls with guaiacyl (4-hydroxy-3-methoxyphenyl) and syringyl (4-hydroxy-3,5-dimethoxyphenyl) moieties to vanillate and syringate. These compounds are further catabolized through the protocatechuate (PCA) 4,5-cleavage (PCA45) pathway. In this article, the regulatory system of the PCA45 pathway is described. A LysR-type transcriptional regulator (LTTR), LigR, activated the transcription of the
ligK-orf1-ligI-lsdA
and
ligJABC
operons in the presence of PCA or gallate (GA), which is an intermediate metabolite of vanillate or syringate, respectively, and repressed transcription of its own gene. LigR bound to the positions −77 to −51 and −80 to −48 of the
ligK
and
ligJ
promoters, respectively, and induced DNA bending. In the presence of PCA or GA, DNA bending on both promoters was enhanced. The LigR-binding regions of the
ligK
and
ligJ
promoters in the presence of inducer molecules were extended and shortened, respectively. The LTTR consensus sequences (Box-K and Box-J) in the
ligK
and
ligJ
promoters were essential for the binding of LigR and transcriptional activation of both operons. In addition, the regions between the LigR binding boxes and the −35 regions were required for the enhancement of DNA bending, although the binding of LigR to the −35 region of the
ligJ
promoter was not observed in DNase I footprinting experiments. This study shows the binding features of LigR on the
ligK
and
ligJ
promoters and explains how the PCA45 pathway genes are expressed during degradation of lignin-derived biaryls by this bacterium.
Functional Characterization of
Synechocystis
sp. Strain PCC 6803
pst1
and
pst2
Gene Clusters Reveals a Novel Strategy for Phosphate Uptake in a Freshwater Cyanobacterium
Authors: Pitt Frances D. , Mazard Sophie , Humphreys Lee , Scanlan David J.
Published: May 2010

Synechocystis
sp. strain PCC 6803 possesses two putative ABC-type inorganic phosphate (P
i
) transporters with three associated P
i
-binding proteins (PBPs), SphX (encoded by
sll0679
), PstS1 (encoded by
sll0680
), and PstS2 (encoded by
slr1247
), organized in two spatially discrete gene clusters,
pst1
and
pst2
. We used a combination of mutagenesis, gene expression, and radiotracer uptake analyses to functionally characterize the role of these PBPs and associated gene clusters. Quantitative PCR (qPCR) demonstrated that
pstS1
was expressed at a high level in P
i
-replete conditions compared to
sphX
or
pstS2
. However, a P
i
stress shift increased expression of
pstS2
318-fold after 48 h, compared to 43-fold for
pstS1
and 37-fold for
sphX
. A shift to high-light conditions caused a transient increase of all PBPs, whereas N stress primarily increased expression of
sphX
. Interposon mutagenesis of each PBP demonstrated that disruption of
pstS1
alone caused constitutive expression of
pho
regulon genes, implicating PstS1 as a major component of the P
i
sensing machinery. The
pstS1
mutant was also transformation incompetent.
32
P
i
radiotracer uptake experiments using
pst1
and
pst2
deletion mutants showed that Pst1 acts as a low-affinity, high-velocity transporter (

K
s

, 3.7 ± 0.7 μM;
V
max
, 31.18 ± 3.96 fmol cell
−1
min
−1
) and Pst2 acts as a high-affinity, low-velocity system (

K
s

, 0.07 ± 0.01 μM;
V
max
, 0.88 ± 0.11 fmol cell
−1
min
−1
). These P
i
ABC transporters thus exhibit differences in both kinetic and regulatory properties, the former trait potentially dramatically increasing the dynamic range of P
i
transport into the cell, which has potential implications for our understanding of the ecological success of this key microbial group.
Treponema denticola
PrcB Is Required for Expression and Activity of the PrcA-PrtP (Dentilisin) Complex
Authors: Godovikova Valentina , Wang Hong-Tao , Goetting-Minesky M. Paula , Ning Yu , Capone Ricardo F. , Slater Claudia K. , Fenno J. Christopher
Published: May 2010

The
Treponema denticola
surface protease complex, consisting of PrtP protease (dentilisin) and two auxiliary polypeptides (PrcA1 and PrcA2), is believed to contribute to periodontal disease by degrading extracellular matrix components and disrupting host intercellular signaling. Previously, we showed that transcription of the protease operon initiates upstream of TDE0760 (herein designated
prcB
), the open reading frame immediately 5′ of
prcA-prtP
. The
prcB
gene is conserved in
T. denticola
strains. PrcB localizes to the detergent phase of Triton X-114 cell surface extracts and migrates as a 22-kDa polypeptide, in contrast to the predicted 17-kDa cytoplasmic protein encoded in the annotated
T. denticola
genome. Consistent with this observation, the PrcB N terminus is unavailable for Edman sequencing, suggesting that it is acylated. Nonpolar deletion of
prcB
in
T. denticola
showed that PrcB is required for production of PrtP protease activity, including native PrtP cleavage of PrcA to PrcA1 and PrcA2. A 6×His-tagged PrcB protein coimmunoprecipitates with native PrtP, using either anti-PrtP or anti-His-tag antibodies, and recombinant PrtP copurifies with PrcB-6×His in nickel affinity chromatography. Taken together, these data are consistent with identification of PrcB as a PrtP-binding lipoprotein that likely stabilizes the PrtP polypeptide during localization to the outer membrane.
RNA Processing of Nitrogenase Transcripts in the CyanobacteriumAnabaena variabilis
Authors: Ungerer Justin L. , Pratte Brenda S. , Thiel Teresa
Published: May 2010

Little is known about the regulation of nitrogenase genes in cyanobacteria. Transcription of thenifH1andvnfHgenes, encoding dinitrogenase reductases for the heterocyst-specific Mo-nitrogenase and the alternative V-nitrogenase, respectively, was studied by using alacZreporter. Despite evidence for a transcription start site just upstream ofnifH1andvnfH, promoter fragments that included these start sites did not drive the transcription oflacZand, fornifH1, did not drive the expression ofnifHDK1. Further analysis using larger regions upstream ofnifH1indicated that a promoter withinnifU1and a promoter upstream ofnifB1both contributed to expression ofnifHDK1, with thenifB1promoter contributing to most of the expression. Similarly, while the region upstream ofvnfH, containing the putative transcription start site, did not drive expression oflacZ, the region that included the promoter for the upstream gene,ava4055, did. Characterization of the previously reportednifH1andvnfHtranscriptional start sites by 5′RACE (5′ rapid amplification of cDNA ends) revealed that these 5′ ends resulted from processing of larger transcripts rather than byde novotranscription initiation. The 5′ positions of both thevnfHandnifH1transcripts lie at the base of a stem-loop structure that may serve to stabilize thenifHDK1andvnfHspecific transcripts compared to the transcripts for other genes in the operons providing the proper stoichiometry for the Nif proteins for nitrogenase synthesis.
Direct and Indirect Control of Late Sporulation Genes by GerR of
Bacillus subtilis
Authors: Cangiano Giuseppina , Mazzone Antonio , Baccigalupi Loredana , Isticato Rachele , Eichenberger Patrick , De Felice Maurilio , Ricca Ezio
Published: May 2010

GerR is a sporulation-specific transcriptional factor of
Bacillus subtilis
that has been identified as a negative regulator of genes transcribed by σ
E
-containing RNA polymerase and as a positive effector of the expression of three late sporulation genes. Here we confirmed that
gerR
transcription is dependent on σ
E
-containing RNA polymerase but also observed that it requires the transcriptional regulator SpoIIID. The study of the role of GerR in regulating the expression of several late sporulation genes allowed us to observe that its effect is strongly positive on
spoVIF
,
cotC
, and
cotG
, weakly positive on
cotB
, and negative on
cotU
. The results of chromatin immunoprecipitation (ChIP) experiments indicated that GerR binds to the promoter regions of some, but not all, of the GerR-controlled genes, leading us to propose that GerR controls late sporulation genes in two ways: (i) directly, by acting on the transcription of
cotB
,
cotU
and
spoVIF
; and (ii) indirectly, through the activation of SpoVIF, which stabilizes the transcriptional activator GerE and consequently induces the expression of the GerE-dependent genes
cotC
and
cotG
.
Genome Sequence of
Lactobacillus crispatus
ST1
Authors: Ojala Teija , Kuparinen Veera , Koskinen J. Patrik , Alatalo Edward , Holm Liisa , Auvinen Petri , Edelman Sanna , Westerlund-Wikström Benita , Korhonen Timo K. , Paulin Lars , Kankainen Matti
Published: May 2010

Lactobacillus crispatus
is a common member of the beneficial microbiota present in the vertebrate gastrointestinal and human genitourinary tracts. Here, we report the genome sequence of
L. crispatus
ST1, a chicken isolate displaying strong adherence to vaginal epithelial cells.
Mutations in the Lipopolysaccharide Biosynthesis Pathway Interfere with Crescentin-Mediated Cell Curvature in
Caulobacter crescentus
Authors: Cabeen Matthew T. , Murolo Michelle A. , Briegel Ariane , Bui N. Khai , Vollmer Waldemar , Ausmees Nora , Jensen Grant J. , Jacobs-Wagner Christine
Published: May 2010

Bacterial cell morphogenesis requires coordination among multiple cellular systems, including the bacterial cytoskeleton and the cell wall. In the vibrioid bacterium
Caulobacter crescentus
, the intermediate filament-like protein crescentin forms a cell envelope-associated cytoskeletal structure that controls cell wall growth to generate cell curvature. We undertook a genetic screen to find other cellular components important for cell curvature. Here we report that deletion of a gene (
wbqL
) involved in the lipopolysaccharide (LPS) biosynthesis pathway abolishes cell curvature. Loss of WbqL function leads to the accumulation of an aberrant O-polysaccharide species and to the release of the S layer in the culture medium. Epistasis and microscopy experiments show that neither S-layer nor O-polysaccharide production is required for curved cell morphology
per se
but that production of the altered O-polysaccharide species abolishes cell curvature by apparently interfering with the ability of the crescentin structure to associate with the cell envelope. Our data suggest that perturbations in a cellular pathway that is itself fully dispensable for cell curvature can cause a disruption of cell morphogenesis, highlighting the delicate harmony among unrelated cellular systems. Using the
wbqL
mutant, we also show that the normal assembly and growth properties of the crescentin structure are independent of its association with the cell envelope. However, this envelope association is important for facilitating the local disruption of the stable crescentin structure at the division site during cytokinesis.
Do in-stream restoration structures enhance salmonid abundance? A meta-analysis
Authors: Whiteway Sarah L. , Biron Pascale M. , Zimmermann André , Venter Oscar , Grant James W.A.
Published: April 2010

Despite the widespread use of stream restoration structures to improve fish habitat, few quantitative studies have evaluated their effectiveness. This study uses a meta-analysis approach to test the effectiveness of five types of in-stream restoration structures (weirs, deflectors, cover structures, boulder placement, and large woody debris) on both salmonid abundance and physical habitat characteristics. Compilation of data from 211 stream restoration projects showed a significant increase in pool area, average depth, large woody debris, and percent cover, as well as a decrease in riffle area, following the installation of in-stream structures. There was also a significant increase in salmonid density (mean effect size of 0.51, or 167%) and biomass (mean effect size of 0.48, or 162%) following the installation of structures. Large differences were observed between species, with rainbow trout ( Oncorhynchus mykiss ) showing the largest increases in density and biomass. This compilation highlights the potential of in-stream structures to create better habitat for and increase the abundance of salmonids, but the scarcity of long-term monitoring of the effectiveness of in-stream structures is problematic.
Mesophilic Clostridia in Puget Sound
Authors: Matches Jack R. , Liston J.
Published: April 2010

Clostridia were isolated from marine sediments collected in Puget Sound in the State of Washington. Sampling stations varied in depth from 10 to 240 m and sediment types varied from sand and gravel to reduced mud. Counts of bacteria growing both aerobically and anaerobically at 30 °C were made. Aerobic and anaerobic counts were 1.21 to 16.9 × 104 and 0.73 to 23.5 × 104 cells/ml of sediment–water slurry respectively. About 30% of the bacteria growing anaerobically were obligate anaerobes and identified as Clostridia. The identified Clostridia fell into 12 groups. The first three groups, containing Clostridium perfringens, C. bifermentans, and C. novyi, made up 76% of the isolates.The results show a variety of species of mesophilic Clostridia in marine sediments with C. perfringens isolated in the highest numbers.
Development and structure of the aleuriospores of Humicola grisea Traaen
Authors: Griffiths D. A.
Published: April 2010

Aleuriospores of H. grisea are bounded by a thick, single-layered cell wall differentiated into an outer, electron-dense melanized zone and an inner, hyaline zone. Melanization was initiated at the periphery of the cell wall and progressed inwards towards the cytoplasm. To distinguish between chlamydospores and aleuriospores, the presence of a secondary cell wall in the former and the presence of a partially melanized, single-layered cell wall in the latter might prove a useful criterion in distinguishing between the two spore types. However, before such a distinction is made, similar studies on other aleuriospore-producing species are necessary.
Facultatively anaerobic nitrogen-fixing bacteria from the marine environment
Authors: Werner Dietrich , Evans Harold J. , Seidler Ramon J.
Published: April 2010

Anaerobic nitrogen fixation in the dark was determined in a natural marine community, developed in a laboratory model ecosystem, at the Oregon State University Marine Science Center in Newport, Oregon. Fixation occurred at a rate of 10 nmol C2H4/cm2 per 24 hours. Two different marine N2-fixing bacteria were isolated from seawater and from sediment at the Oregon coast. These bacterial isolates were identified as Klebsiella pneumoniae and Enterobacter aerogenes. Within a growth period of 100 h K. pneumoniae fixed 3.6 mmol N2 per liter and E. aerogenes fixed 1.2 mmol N2 per liter. The influence of seawater on N2-fixation activity of these bacteria was compared with that of bacteria from a non-marine origin. The nitrogenase activity of a crude cell-free extract of E. aerogenes was dependent upon ATP and Na2S2O4 and proceeded at a rate of 3.9 nmol C2H4 per minute per milligram protein.
Causes of the inhibition of growth of Escherichia coli K12 by chlorate
Authors: Newman E. B. , Fida Asghar , Kapoor V.
Published: April 2010

Chlorate inhibited the aerobic growth of Escherichia coli K12 in at least two ways, here termed type I and type II inhibition. Type I inhibition was reversed by shikimic acid or by a group of four amino acids (tyrosine, phenylalanine, tryptophane, and methionine), or by nitrate at much higher concentrations. Type I inhibition involved the metabolism of chlorate via nitrate reductase to a toxic form which apparently interfered with aromatic amino acid biosynthesis. The occurrence of type I inhibition is affected by the particular carbon and energy source supplied. Type II inhibition involved chlorate itself, or a derivative not formed by nitrate reductase. The extent of the inhibition was affected by L-serine, methionine, and sodium formate.
Immunological response of guinea pigs experimentally infected with Histoplasma duboisii
Authors: Aly Raza , Larsh Howard W.
Published: April 2010

There was no significant difference in serological titers when different groups of guinea pigs (Hartley strain) infected with varying doses of mycelial phase of Histoplasma duboisii (one, two, seven, and no injections) were superinfected with Listeria monocytogenes 6 months later. The immunological response of infected animals which received two biweekly intraperitoneal injections of Histoplasma duboisii and were superinfected after 40 days with homologous and heterologous organisms was used for comparison. In general, animals receiving a single injection of Histoplasma duboisii had no complement-fixing antibodies against this antigen; however, positive skin and precipitin reactions did occur. Animals receiving several injections of Histoplasma duboisii had a higher complement-fixation titer (1:16 to 1:256) than those with two injections (1:8 to 1:32). After superinfection with Listeria monocytogenes, animals which received seven injections of Histoplasma duboisii showed a slight reduction in the number of rosette-forming cells against Listeria monocytogenes antigens when compared with the controls.
Expériences sur la nature de particules trouvées dans des cas d'hépatite virale: type coronavirus, antigène Australia et particules de Dane
Authors: Ackermann H.-W. , Cherchel G. , Valet J.-P. , Matte J. , Moorjani S. , Higgins R.
Published: April 2010

Coronavirus-like serum particles, Australia antigen, and Dane particles were treated by various chemicals and enzymes. Results were studied by electron microscopy. Coronavirus-like particles have no nucleocapsid, no detectable nucleic acid, no antigenic relationships with Australia antigen, and seem to be phospholipoproteins. Similar particles have been found in sera of guinea pigs and in human lipoproteins, especially in the HDL and VHDL fractions. Australia antigen which appears devoid of nucleic acid, and the envelope of Dane particles are sensitive to most agents and behave as phospholipoproteins. Phospholipase C produces ring-like structures. Results differ markedly from those obtained by other workers. The capsid of Dane particles is resistant to most agents. It is separated from the envelope by Tween 80, urea, and other agents. Dane particles seem to contain nucleic acid.
Characteristic cytoplasmic structures in microorganisms utilizing n-butane and 1-butanol
Authors: Kormendy Agnes C. , Wayman Morris
Published: April 2010

Intracellular structures were observed in two Arthrobacter spp. and in Candida utilis in media containing n-butane or 1-butanol as the sole source of carbon; these structures were absent in the same organisms grown in the presence of glucose. These substrate-specific structures consisted of electron-dense bodies nearly surrounded by a round electron-transparent area, and connected to the main cytoplasm by a bridge. These structures may represent sites of hydrocarbon or alcohol oxidation, and the name "oxisome" is proposed for them. The microorganisms contained about 8 times as much iron when growing on n-butane as when growing on glucose, and about 3 to 4.5 times as much when growing on 1-butanol. When one of the Arthrobacter sp. was grown on n-butane in the absence of iron, more diffuse and less structured concentrations of electron-dense particles appeared. Extraction of n-butane-grown cells suggests that the electron transport system is different from other known electron carriers.
The fine structure of some strains of Humicola Traaen
Authors: Bertoldi M. de , Mariotti F. , Filippi C.
Published: April 2010

The fine structure of three unclassified strains of Humicola and of H. grisea has been investigated. The hyphae of all the strains show septa with Woronin bodies of the ascomycetous type. The cytoplasm contains many nuclei per cell, mitochondria, ribosomes, and endoplasmic vesicles, all typical of fungal cells. Electron-microscopic studies of thin sections of mature aleuriospores reveal a thick multilayered cell wall and an accumulation, inside the spore, of β-hydroxybutyrate granules. Aleuriospores exhibit different types of cell surface; the outer wall layer of two strains is smooth, while the outer layer of the other strains is rough because of the presence of melanizing bodies on the cell wall matrix. The fine structure of phialospores and microconidia is also described. Differences in the fine structure among the strains studied are reported.
Vector capability of Aedes aegypti mosquitoes for California encephalitis and dengue viruses at various temperatures
Authors: McLean Donald M. , Clarke Alison M. , Coleman Jonathan C. , Montalbetti Charles A. , Skidmore Ann G. , Walters Teresa E. , Wise Richard
Published: April 2010

A Yukon strain of California encephalitis virus (snowshoe hare subtype) was transmitted by bites of laboratory-bred Aedes aegypti mosquitoes after 3 weeks of extrinsic incubation at 80°F and after 4 weeks at 55°F after intrathoracic injection. Transmission first occurred after 4 weeks incubation at 80 or 55°F when mosquitoes were infected by feeding. Zero-passage strains of dengue-2 virus were transmitted after 6 days of extrinsic incubation at 90°F after feeding or intrathoracic injection, after 6 to 13 days incubation at 75°F following injection, after 13 days at 80°F following feeding, and after 13 to 27 days at 55°F following injection. Although virtually all mosquitoes were infected at the time transmission occurred, California encephalitis virus was transmitted by less than 50% of mosquitoes, but 80% or more of mosquitoes infected with the dengue-2 strains transmitted virus. Enveloped virions about 35 nm diameter were observed in the cytoplasm of acini of salivary glands of mosquitoes infected with dengue-2 virus.
A new acidophilic Scytalidium
Authors: Sigler Lynne , Carmichael J. W.
Published: April 2010

A brown mold fungus was isolated from acid soil and from acid solutions in an industrial plant and a uranium mine. The only type of spores observed were arthroconidia. The morphology of the fungus is illustrated and it is described as a new species, Scytalidium acidophilum.
Separable forms of nuclease secreted by Staphylococcus aureus as a function of growth stage
Authors: Carpenter David , Chesbro William
Published: April 2010

The growth characteristics and nuclease secretion patterns of Staphylococcus aureus, strains UNH-15 and Foggi, were investigated. Strain Foggi grew more rapidly, but the rate of its nuclease secretion was slower than that of UNH-15. And though the terminal turbidities of both strains were about equal, the final nuclease yields of UNH-15 were 15–20% higher than Foggi's.Three chromatographically and electrophoretically separable forms of nuclease were present in the culture supernatants of these strains. Designated nucleases I, II, and III, in order of their elution from carboxymethylcellulose columns, the forms were not produced simultaneously and their relative concentrations changed during the growth cycle. During the log phase growth, I and II were produced. Near the end of this phase, III began to appear, while I and II were concurrently disappearing from the culture. Only III was present in the supernatant fluid of stationary phase cultures.Molecular sieving of the forms in G-75 Sephadex and electrophoresis in SDS-polyacrylamide indicated that the molecular weights of the I, II, and III forms were about 7 000, 14 000, and 20 000 respectively. Commercially available micrococcal nuclease appears to be electrophoretically identical with a mixture of forms II and III.
Virus cytomégalique (VCM) humain et immunofluorescence indirecte dans le lupus érythèmateux disséminé (LED)
Authors: Montplaisir Serge , Martineau Bernard
Published: April 2010

not available
Pyrimidine metabolism in Pseudomonas acidovorans
Authors: Kelln Rod A. , Warren R. A. J.
Published: April 2010

Pseudomonas acidovorans lacks a number of enzymes of the salvage pathways of nucleic acid metabolism, including uridine phosphorylase, purine nucleoside phosphorylase, cytidine (deoxycytidine) deaminase and thymidine phosphorylase, and probably uridine kinase and deoxycytidine kinase. Its growth is inhibited by adenosine and deoxyadenosine. The level of aspartate transcarbamylase is the same in extracts of P. acidovorans grown in minimal medium ± 25 μg uracil/ml, and the enzyme appears to be insensitive to nucleotides which affect this enzyme in other bacteria. Growth of two pyrimidine-requiring mutants of P. acidovorans is supported by uracil or cytosine but not by their nucleosides nor by intermediates of the de novo pyrimidine biosynthetic pathway. Concentrations of uracil greater than 50 μg/ml have the unusual effect of lengthening the lag period of the mutants. The wild-type strain is not inhibited by uracil.
The cell-bound protease of Bacteroides amylophilus H18
Authors: Blackburn T. H. , Hullah W. A.
Published: April 2010

Most of the cell-bound protease activity of Bacteroides amylophilus was attached to lysozyme spheroplasts (79%) and to the ruptured spheroplast envelope (48%). Protease activity also remained bound to mechanically ruptured cell envelopes from which it could be liberated by n-butanol treatment.Butanol-liberated protease activity was purified 80-fold, contained 23% RNA, and was excluded from G-200 Sephadex. Small molecular weight protease activity could not be liberated from this complex by treatment with acetone, EDTA, or urea. RNA could not be separated from the protease activity by treatment with streptomycin sulfate, MgCl2, or sodium dodecyl sulfate but was separated from the protein by phenol extraction. Protamine sulfate precipitation gave variable results. It is concluded that the cell-bound protease remains firmly bound to cellular components from which it cannot be liberated easily.
Mechanism of regulation of the malic enzyme from Fusarium
Authors: Zink M. W.
Published: April 2010

The NADP-specific malic enzyme which catalyzes the oxidative decarboxylation of malic acid has been partially purified from extracts of Fusarium oxysporum and some of its kinetic parameters studied. Reciprocal velocity plots with malate as variable substrate are nonlinear except at high NADP concentration, while with NADP as variable substrate the reciprocal plots are linear. Substrate activation by malic acid describes a biphasic character in reciprocal plots. Kinetic studies indicate that there are two binding sites for malic acid. At saturating levels of NADP, two Km components for malic acid, designated as [Formula: see text] and [Formula: see text] are evident. The separation of the two components may have been accomplished; [Formula: see text] component by mercaptosuccinic acid and [Formula: see text] component by either low pH or by phosphate. Inhibition of the purified malic enzyme is nontotal with fructose 1,6-diphosphate, 6-phosphogluconic acid, and 3-phos-phoglyceric acid. The kinetic relationship between fructose 1,6-diphosphate or 6-phospho-gluconate and malic acid is competitive with respect to the [Formula: see text] component and noncompetitive with [Formula: see text] component. Inhibition by 3-phosphoglyceric acid and oxaloacetate with respect to both components is noncompetitive and competitive, respectively. The significance of negative cooperativity and the effect of the above-mentioned inhibitors is discussed.
Serological survey of Pseudomonas aeruginosa strains isolated from patients in Canadian hospitals
Authors: Sato H. , Diena B. B.
Published: April 2010

Eight hundred and eleven strains of Pseudomonas aeruginosa isolated in Canadian hospitals were serotyped by the method of Lanyi. Strains of serogroup 4 were found to be predominant (25.4%). Six serogroups, namely 4, 3, 7, 2, 5, and 6 comprised close to 75% of the isolates studied.There was no correlation between serogroups and the source of isolates, on one hand, and some biophysical properties of the strains (mucoid colony type, pigment production), on the other.The same serotype of Pseudomonas aeruginosa persisted in most of the patients. Many of them, however, yielded a different serotype in follow-up studies.
The mechanism of bacteriophage T4 neutralization: effects of univalent antibody fragments on T4 adsorption kinetics
Authors: Stemke G. W. , Knight W. S. , Butz E. , Gates D. J.
Published: April 2010

Bacteriophage T4 is neutralized by univalent antibody fragment Fab′ with apparent two-target neutralization kinetics. By the use of conditional lethal (amber) T4 mutants, it was shown that partially neutralized preparations of phages adsorb to bacteria with kinetics suggesting a mixture of fast and slow adsorbers; the ratio of fast to slow phages fits well that predicted by Poisson distribution of phages with, respectively, no (zero hit) and one (one hit) Fab′ complexed. A portion of the infectivity of one-hit phages seems due to phage–Fab′ dissociation, but the larger portion (80%) of the infectivity is due to weak adsorption of phages complexed still with one Fab′. It was shown that antibody to tail fiber is responsible for this effect. Phage adsorption heterogeneity was a possible explanation of kinetics obtained using phages which had not been treated with Fab′.
Biogenesis of zearalenone (F-2) by Fusarium roseum 'Graminearum'
Authors: Steele John A. , Lieberman John R. , Mirocha C. J.
Published: April 2010

The biogenesis of zearalenone or F-2 (2,4-dihydroxy-6-(10-hydroxy-6-oxo-trans-1-undecenyl) benzoic acid lactone) was examined. Of several possible precursors, acetate and malonate were incorporated most readily, and malonate was shown to inhibit incorporation from acetate. Zearalenone isolated from cultures of Fusarium roseum fed 1-14C-acetate was chemically degraded and the distribution of 14C examined. Both the kinetic and degradation studies suggest that zearalenone is derived from acetate through the polyketide pathway.
Disappearance of the covalently closed circular cryptic plasmid PO-2 in Salmonella pullorum MS35 containing F77
Authors: Stiffler Paul W. , Schoenhard D. E.
Published: April 2010

The physical basis of the donor property of Salmonella pullorum donor strains MS8300, MS830, and MS831 carrying the F77 factor from Salmonella typhimurium was investigated by dye-buoyant density equilibrium centrifugation and zonal centrifugation in neutral sucrose gradients. Centrifugation of the MS8300 and MS831 closed circular DNA material in a 20 to 31% neutral sucrose gradient resulted in a profile having one sharp peak of radioactivity with a sedimentation coefficient of 17 S and a broad peak extending from 65 to 70 S. The 17- and 65-S species were isolated from the isogenic F− strain MS83. These appeared identical with those isolated previously in S. pullorum MS53 as the cryptic plasmids PO-1 and PO-2 respectively. Cosedimentation of differentially labeled F77 DNA and the lysate containing the 65-S and 70-S species suggested that the 70-S species is the autonomous F77 factor in strains MS8300 and MS831. Lysates of MS830 similarly treated produced a profile containing the 17-S molecule and possibly some 70-S molecules but no 65-S molecules. It was concluded that the F77 factor was integrated in most cells and that the covalently closed circular state of PO-2 plasmid was lost. The mutation in the cysE gene of the F77 factor carried by MS831 had no apparent effect on the covalently closed circular nature of PO-2 plasmid, although F77 no longer seemed to mobilize the chromosome from the cysE locus.
Radiation response of energy-deficient yeast mutants: the relationship of radioresistance to respiratory and catalase activities as measured by oxygen polarography
Authors: Bruce Alan K. , Parker John H.
Published: April 2010

The radiation response of a group of respiration-deficient mutants of yeast was determined. Respiration and catalase activity was measured by a polarographic technique. Radiation response, as measured by D0, is correlated with both respiratory and catalase activities. Cultures grown in chloramphenicol were also examined. In these cultures, radiation response (D0) and respiration were both markedly decreased while catalase activity was generally increased. From these data we conclude that respiratory capacity may be involved in determining the radiation sensitivity of yeast cultures whereas catalase activity does not participate. Further, although the enzymes of the respiratory system and those generally associated with the peroxisome are similar chemically and functionally, they are controlled by different regulation systems.
Fermentation patterns of some lactose-negative enteric bacteria
Authors: Altenbern Robert A.
Published: April 2010

Organic acids produced during fermentative growth of many lactose-negative members of Enterobacteriaceae have been determined quantitatively by thin-layer chromatography. Nearly all organisms examined elaborated succinic acid and many also produced fumaric and (or) pyruvic acid in varying ratios. Some differentiation of the genera could be achieved by calculation of the ratio of succinic/fumaric acid or succinic/pyruvic acid. Anaerogenic Salmonella strains and all Shigella species exhibited a succinic to fumaric acid ratio of less than 1.0. Aerogenic Salmonella strains yielded a succinic to fumaric acid ratio of 2.3 to 4.3. Proteus vulgaris and Proteus mirabilis were the only species examined that produced pyruvic acid in addition to succinic acid and fumaric acid. Strains of Edwardsiella tarda showed a broad range of succinic to fumaric acid ratios from 2.4 to 8.5. The single strain of Providencia alcalifaciens that was examined yielded only succinic acid and could be readily differentiated from other organisms examined.
Physical characteristics of new coliphages
Authors: Berg G. J. , Berryhill D. L. , Borg T. K.
Published: April 2010

Seven new bacteriophages for Escherichia coli B, isolated from a farm animal waste lagoon, were characterized in regard to morphology, buoyant density, UV-sensitivity, and heat-sensitivity.
Variation in the occurrence of extracellular diffusible antigens in temperature-induced variants of Erwinia herbicola Y46, and observations of their relationships with Erwinia amylovora
Authors: Gibbins L. N.
Published: April 2010

Temperature-induced, non-pigmented, auxotrophic derivatives of Erwinia herbicola Y46 show variation in their extracellular diffusible antigens, both among themselves, and with the parent strain. The pattern of variation did not correspond to those of other observed physiological differences. A variable, but minor, degree of cross-reaction with Erwinia amylovora 595 was observed. Ultrasonic disruption of E. herbicola cells revealed a major antigen component in some variants. However, this method reduced the precipitation of some other components, and is recommended for use in antigen preparation in these organisms only under carefully specified conditions. None of the E. herbicola variants tested were phytopathogenic to pear fruitlets.
Improved staining of extracellular polymer surrounding Eucapsis sp. and Anabena cylindrica: a comparative study
Authors: Cagle Gerald D.
Published: April 2010

Extracellular polymer surrounding two blue-green algae, Eucapsis sp. (No. 1519) and Anabena cylindrica Lemm. (No. 629), was examined with the electron microscope. Conventional glutaraldehyde–OsO4 fixation, freeze-drying before fixation, and two ruthenium red staining procedures (Luft's method and the modified method of Cagle et al.) were used. The data obtained indicate that observation of extracellular polymer is successively enhanced over conventional fixation when (i) freeze-drying, (ii) Luft's ruthenium red method, and (iii) the modified method of Cagle et al. are used. Each of the methods was also observed to improve cytological detail, particularly in A. cylindrica.