bluuebunny/crossref_metadata_2025_split huggingface dataset:
Improved Secretion of Native Human Insulin-Like Growth Factor 1 from
gas1
Mutant
Saccharomyces cerevisiae
Cells
Authors: Vai Marina , Brambilla Luca , Orlandi Ivan , Rota Nicola , Ranzi Bianca Maria , Alberghina Lilia , Porro Danilo 
Published: July 2002

ABSTRACT

We studied the secretion of recombinant human insulin-like growth factor 1 (rhIGF-1) from transformed yeast cells. The
hIGF-1
gene was fused to the mating factor α prepro- leader sequence under the control of the constitutive
ACT1
promoter. We found that the inactivation of the
GAS1
gene in the host strain led to a supersecretory phenotype yielding a considerable increase, from 8 to 55 mg/liter, in rhIGF-1 production.
Endosymbiotic Microbiota of the Bamboo PseudococcidAntonina crawii(Insecta, Homoptera)
Authors: Fukatsu Takema , Nikoh Naruo 
Published: July 2002

ABSTRACTWe characterized the intracellular symbiotic microbiota of the bamboo pseudococcidAntonina crawiiby performing a molecular phylogenetic analysis in combination with in situ hybridization. Almost the entire length of the bacterial 16S rRNA gene was amplified and cloned fromA. crawiiwhole DNA. Restriction fragment length polymorphism analysis revealed that the clones obtained included three distinct types of sequences. Nucleotide sequences of the three types were determined and subjected to a molecular phylogenetic analysis. The first sequence was a member of the γ subdivision of the divisionProteobacteria(γ-Proteobacteria) to which no sequences in the database were closely related, although the sequences of endosymbionts of other homopterans, such as psyllids and aphids, were distantly related. The second sequence was a β-Proteobacteriasequence and formed a monophyletic group with the sequences of endosymbionts from other pseudococcids. The third sequence exhibited a high level of similarity to sequences ofSpiroplasmaspp. from ladybird beetles and a tick. Localization of the endosymbionts was determined by using tissue sections ofA. crawiiand in situ hybridization with specific oligonucleotide probes. The γ- and β-Proteobacteriasymbionts were packed in the cytoplasm of the same mycetocytes (or bacteriocytes) and formed a large mycetome (or bacteriome) in the abdomen. The spiroplasma symbionts were also present intracellularly in various tissues at a low density. We observed that the anterior poles of developing eggs in the ovaries were infected by the γ- and β-Proteobacteriasymbionts in a systematic way, which ensured vertical transmission. Five representative pseudococcids were examined by performing diagnostic PCR experiments with specific primers; the β-Proteobacteriasymbiont was detected in all five pseudococcids, the γ-Proteobacteriasymbiont was found in three, and the spiroplasma symbiont was detected only inA. crawii.
Prevention of Yeast Spoilage in Feed and Food by the Yeast Mycocin HMK
Authors: Lowes K. F. , Shearman C. A. , Payne J. , MacKenzie D. , Archer D. B. , Merry R. J. , Gasson M. J. 
Published: July 2002

ABSTRACTThe yeastWilliopsis mrakiiproduces a mycocin or yeast killer toxin designated HMK; this toxin exhibits high thermal stability, high pH stability, and a broad spectrum of activity against other yeasts. We describe construction of a synthetic gene for mycocin HMK and heterologous expression of this toxin inAspergillus niger. Mycocin HMK was fused to a glucoamylase protein carrier, which resulted in secretion of biologically active mycocin into the culture media. A partial purification protocol was developed, and a comparison with nativeW. mrakiimycocin showed that the heterologously expressed mycocin had similar physiological properties and an almost identical spectrum of biological activity against a number of yeasts isolated from silage and yoghurt. Two food and feed production systems prone to yeast spoilage were used as models to assess the ability of mycocin HMK to act as a biocontrol agent. The onset of aerobic spoilage in mature maize silage was delayed by application ofA. nigermycocin HMK on opening because the toxin inhibited growth of the indigenous spoilage yeasts. This helped maintain both higher lactic acid levels and a lower pH. In yoghurt spiked with dairy spoilage yeasts,A. nigermycocin HMK was active at all of the storage temperatures tested at which yeast growth occurred, and there was no resurgence of resistant yeasts. The higher the yeast growth rate, the more effective the killing action of the mycocin. Thus, mycocin HMK has potential applications in controlling both silage spoilage and yoghurt spoilage caused by yeasts.
Biochemical and Molecular Characterization of a Laccase from
Marasmius quercophilus
Authors: Dedeyan Boghos , Klonowska Agnieszka , Tagger Simone , Tron Thierry , Iacazio Gilles , Gil Gérard , Le Petit Jean 
Published: July 2002

ABSTRACT

The basidiomycete
Marasmius quercophilus
is commonly found during autumn on the decaying litter of the evergreen oak (
Quercus ilex
L.), a plant characteristic of Mediterranean forest. This white-rot fungus colonizes the leaf surface with rhizomorphs, causing a total bleaching of the leaf. In synthetic liquid media, this white-rot fungus has strong laccase activity. From a three-step chromatographic procedure, we purified a major isoform to homogeneity. The gene encodes a monomeric glycoprotein of approximately 63 kDa, with a 3.6 isoelectric point, that contains 12% carbohydrate. Spectroscopic analysis of the purified enzyme (UV/visible and electron paramagnetic resonance, atomic absorption) confirmed that it belongs to the “blue copper oxidase” family. With syringaldazine as the substrate, the enzyme's pH optimum was 4.5, the optimal temperature was 75°C, and the

K
m

was 7.1 μM. The structural gene,
lac1
, was cloned and sequenced. This gene encodes a 517-amino-acid protein 99% identical to a laccase produced by PM1, an unidentified basidiomycete previously isolated from wastewater from a paper factory in Spain. This similarity may be explained by the ecological distribution of the evergreen oak in Mediterranean forest.
Nickel Availability and
hupSL
Activation by Heterologous Regulators Limit Symbiotic Expression of the
Rhizobium leguminosarum
bv. Viciae Hydrogenase System in Hup
−
Rhizobia
Authors: Brito Belén , Monza Jorge , Imperial Juan , Ruiz-Argüeso Tomás , Palacios Jose Manuel 
Published: July 2002

ABSTRACT

A limited number of
Rhizobium
and
Bradyrhizobium
strains possess a hydrogen uptake (Hup) system that recycles the hydrogen released from the nitrogen fixation process in legume nodules. To extend this ability to rhizobia that nodulate agronomically important crops, we investigated factors that affect the expression of a cosmid-borne Hup system from
Rhizobium leguminosarum
bv. viciae UPM791 in
R. leguminosarum
bv. viciae,
Rhizobium etli
,
Mesorhizobium loti
, and
Sinorhizobium meliloti
Hup
−
strains. After cosmid pAL618 carrying the entire
hup
system of strain UPM791 was introduced, all recipient strains acquired the ability to oxidize H
2
in symbioses with their hosts, although the levels of hydrogenase activity were found to be strain and species dependent. The levels of hydrogenase activity were correlated with the levels of nickel-dependent processing of the hydrogenase structural polypeptides and with transcription of structural genes. Expression of the NifA-dependent
hupSL
promoter varied depending on the genetic background, while the
hyp
operon, which is controlled by the FnrN transcriptional regulator, was expressed at similar levels in all recipient strains. With the exception of the
R. etli
-bean symbiosis, the availability of nickel to bacteroids strongly affected hydrogenase processing and activity in the systems tested. Our results indicate that efficient transcriptional activation by heterologous regulators and processing of the hydrogenase as a function of the availability of nickel to the bacteroid are relevant factors that affect hydrogenase expression in heterologous rhizobia.
Superoxide Dismutase Activity in
Pseudomonas putida
Affects Utilization of Sugars and Growth on Root Surfaces
Authors: Kim Young Cheol , Miller Charles D. , Anderson Anne J. 
Published: July 2002

ABSTRACT

To investigate the role of superoxide dismutases (SOD) in root colonization and oxidative stress, mutants of
Pseudomonas putida
lacking manganese-superoxide dismutase (MnSOD) (
sodA
), iron-superoxide dismutase (FeSOD) (
sodB
), or both were generated. The
sodA sodB
mutant did not grow on components washed from bean root surfaces or glucose in minimal medium. The
sodB
and
sodA sodB
mutants were more sensitive than wild type to oxidative stress generated within the cell by paraquat treatment. In single inoculation of SOD mutants on bean, only the
sodA sodB
double mutant was impaired in growth on root surfaces. In mixed inoculations with wild type, populations of the
sodA
mutant were equal to those of the wild type, but levels of the
sodB
mutant and, to a great extent, the
sodA sodB
mutant, were reduced. Confocal microscopy of young bean roots inoculated with green fluorescent protein-tagged cells showed that wild type and SOD single mutants colonized well predominantly at the root tip but that the
sodA sodB
double mutant grew poorly at the tip. Our results indicate that FeSOD in
P. putida
is more important than MnSOD in aerobic metabolism and oxidative stress. Inhibition of key metabolic enzymes by increased levels of superoxide anion may cause the impaired growth of SOD mutants in vitro and in planta.
Influence of Cadmium and Mercury on Activities of Ligninolytic Enzymes and Degradation of Polycyclic Aromatic Hydrocarbons by
Pleurotus ostreatus
in Soil
Authors: Baldrian Petr , in der Wiesche Carsten , Gabriel Jiří , Nerud František , Zadražil František 
Published: July 2002

ABSTRACT

The white-rot fungus
Pleurotus ostreatus
was able to degrade the polycyclic aromatic hydrocarbons (PAHs) benzo[
a
]anthracene, chrysene, benzo[
b
]fluoranthene, benzo[
k
]fluoranthene, benzo[
a
]pyrene, dibenzo[
a
,
h
]anthracene, and benzo[
ghi
]perylene in nonsterile soil both in the presence and in the absence of cadmium and mercury. During 15 weeks of incubation, recovery of individual compounds was 16 to 69% in soil without additional metal. While soil microflora contributed mostly to degradation of pyrene (82%) and benzo[
a
]anthracene (41%), the fungus enhanced the disappearance of less-soluble polycyclic aromatic compounds containing five or six aromatic rings. Although the heavy metals in the soil affected the activity of ligninolytic enzymes produced by the fungus (laccase and Mn-dependent peroxidase), no decrease in PAH degradation was found in soil containing Cd or Hg at 10 to 100 ppm. In the presence of cadmium at 500 ppm in soil, degradation of PAHs by soil microflora was not affected whereas the contribution of fungus was negligible, probably due to the absence of Mn-dependent peroxidase activity. In the presence of Hg at 50 to 100 ppm or Cd at 100 to 500 ppm, the extent of soil colonization by the fungus was limited.
Expression of
nifH
Genes in Natural Microbial Assemblages in Lake George, New York, Detected by Reverse Transcriptase PCR
Authors: Zani Sabino , Mellon Mark T. , Collier Jackie L. , Zehr Jonathan P. 
Published: July 2002

ABSTRACT

A modified nested reverse transcriptase PCR (RT-PCR) method was used to detect the expression of nitrogenase genes in meso-oligotrophic Lake George, New York. Net (>20-μm pore size) plankton samples collected from two sites (Dome Island and Hague Marina) were extracted for total RNA and genomic DNA to determine the identity of diazotrophic organisms that were present and those that were actively expressing nitrogenase genes. Phylogenetic analysis of individual sequences cloned from PCR amplifications showed that there were phylogenetically diverse groups of bacteria that possessed a
nifH
gene, including representatives of unicellular and filamentous cyanobacteria, the α- and γ-subdivisions of the division
Proteobacteria
(α- and γ-proteobacteria), and a previously undefined group of bacteria. The phylotypes cloned from RT-PCR amplifications, which were actively expressing
nifH
transcripts, clustered with the unicellular and filamentous cyanobacteria, α-proteobacteria, and the novel bacterial cluster. No bacterial sequences were found which clustered with sequences from cluster II (alternative nitrogenases), III (nitrogenases in strict anaerobes), or IV (
nifH
-like sequences). These results indicate that there were several distinct groups of nitrogen-fixing microorganisms in the net plankton from both sampling sites and that most of the groups had representative phylotypes that were actively expressing nitrogenase genes.
Purification and Biochemical Characterization of Mutacin I from the Group I Strain of
Streptococcus mutans
, CH43, and Genetic Analysis of Mutacin I Biosynthesis Genes
Authors: Qi Fengxia , Chen Ping , Caufield Page W. 
Published: July 2002

ABSTRACT

Previously, we reported isolation and characterization of mutacin III and genetic analysis of mutacin III biosynthesis genes from the group III strain of
Streptococcus mutans
, UA787 (F. Qi, P. Chen, and P. W. Caufield, Appl. Environ. Microbiol. 65:3880–3887, 1999). During the same process of isolating the mutacin III structural gene, we also cloned the structural gene for mutacin I. In this report, we present purification and biochemical characterization of mutacin I from the group I strain CH43 and compare mutacin I and mutacin III biosynthesis genes. The mutacin I biosynthesis gene locus consists of 14 genes in the order
mutR
, -
A
, -
A
′, -
B
, -
C
, -
D
, -
P
, -
T
, -
F
, -
E
, -
G
,
orfX
,
orfY
,
orfZ. mutA
is the structural gene for mutacin I, while
mutA
′ is not required for mutacin I activity. DNA and protein sequence analysis revealed that mutacins I and III are homologous to each other, possibly arising from a common ancestor. The mature mutacin I is 24 amino acids in size and has a molecular mass of 2,364 Da. Ethanethiol modification and peptide sequencing of mutacin I revealed that it contains six dehydrated serines, four of which are probably involved with thioether bridge formation. Comparison of the primary sequence of mutacin I with that of mutacin III and epidermin suggests that mutacin I likely has the same bridging pattern as epidermin.
Iron Stress in Open-Ocean Cyanobacteria (
Synechococcus
,
Trichodesmium
, and
Crocosphaera
spp.): Identification of the IdiA Protein
Authors: Webb E. A. , Moffett J. W. , Waterbury J. B. 
Published: July 2002

ABSTRACT

Cyanobacteria are prominent constituents of the marine biosphere that account for a significant percentage of oceanic primary productivity. In an effort to resolve how open-ocean cyanobacteria persist in regions where the Fe concentration is thought to be limiting their productivity, we performed a number of Fe stress experiments on axenic cultures of marine
Synechococcus
spp.
, Crocosphaera
sp.
,
and
Trichodesmium
sp. Through this work, we determined that all of these marine cyanobacteria mount adaptive responses to Fe stress, which resulted in the induction and/or repression of several proteins. We have identified one of the Fe stress-induced proteins as an IdiA homologue. Genomic observations and laboratory data presented herein from open-ocean
Synechococcus
spp. are consistent with IdiA having a role in cellular Fe scavenging. Our data indicate that IdiA may make an excellent marker for Fe stress in open-ocean cyanobacterial field populations. By determining how these microorganisms respond to Fe stress, we will gain insight into how and when this important trace element can limit their growth in situ
.
This knowledge will greatly increase our understanding of how marine Fe cycling impacts oceanic processes, such as carbon and nitrogen fixation.
Study of Genetic Diversity of Eukaryotic Picoplankton in Different Oceanic Regions by Small-Subunit rRNA Gene Cloning and Sequencing
Authors: Dı́ez Beatriz , Pedrós-Alió Carlos , Massana Ramon 
Published: July 2002

ABSTRACT

Very small eukaryotic organisms (picoeukaryotes) are fundamental components of marine planktonic systems, often accounting for a significant fraction of the biomass and activity in a system. Their identity, however, has remained elusive, since the small cells lack morphological features for identification. We determined the diversity of marine picoeukaryotes by sequencing cloned 18S rRNA genes in five genetic libraries from North Atlantic, Southern Ocean, and Mediterranean Sea surface waters. Picoplankton were obtained by filter size fractionation, a step that excluded most large eukaryotes and recovered most picoeukaryotes. Genetic libraries of eukaryotic ribosomal DNA were screened by restriction fragment length polymorphism analysis, and at least one clone of each operational taxonomic unit (OTU) was partially sequenced. In general, the phylogenetic diversity in each library was rather great, and each library included many different OTUs and members of very distantly related phylogenetic groups. Of 225 eukaryotic clones, 126 were affiliated with algal classes, especially the Prasinophyceae, the Prymnesiophyceae, the Bacillariophyceae, and the Dinophyceae. A minor fraction (27 clones) was affiliated with clearly heterotrophic organisms, such as ciliates, the chrysomonad
Paraphysomonas
, cercomonads, and fungi. There were two relatively abundant novel lineages, novel stramenopiles (53 clones) and novel alveolates (19 clones). These lineages are very different from any organism that has been isolated, suggesting that there are previously unknown picoeukaryotes. Prasinophytes and novel stramenopile clones were very abundant in all of the libraries analyzed. These findings underscore the importance of attempts to grow the small eukaryotic plankton in pure culture.
The Viable But Nonculturable State of
Ralstonia solanacearum
May Be Involved in Long-Term Survival and Plant Infection
Authors: Grey Brian E. , Steck Todd R. 
Published: July 2002

ABSTRACT

The role of the dormant-like viable but nonculturable (VBNC) condition in the etiology of bacterial infection was examined using a plant system. The plant-pathogenic bacterium
Ralstonia solanacearum
was first shown to enter into the VBNC state both in response to cupric sulfate when in a saline solution and when placed in autoclaved soil. To determine if the VBNC condition is related to pathogenesis, the physiological status of bacteria recovered from different regions of inoculated tomato plants was determined at different stages of infection. The fraction of in planta bacteria that were VBNC increased during infection and became greater than 99% by the late stage of disease. The possibility that soil-dwelling VBNC bacteria may resuscitate and infect plants was also examined. When tomato seeds were germinated in sterile soil that contained VBNC but no detectable culturable forms of
R. solanacearum
cells, resuscitation was observed to occur in soil adjacent to plant roots; these resuscitated bacteria were able to infect plants. This is the first report of
R. solanacearum
entering the VBNC state and of resuscitation of any VBNC plant-pathogenic bacteria and provides evidence that the VBNC state may be involved in explaining the persistent nature of some infections.
Direct Incorporation of Glucosamine and
N
-Acetylglucosamine into Exopolymers by
Gluconacetobacter xylinus
(=
Acetobacter xylinum
) ATCC 10245: Production of Chitosan-Cellulose and Chitin-Cellulose Exopolymers
Authors: Lee Jin W. , Deng Fang , Yeomans Walter G. , Allen Alfred L. , Gross Richard A. , Kaplan David L. 
Published: July 2002

ABSTRACT

Gluconacetobacter xylinus
(=
Acetobacter xylinum
) ATCC 10245 incorporated 2-amino-2-deoxy-
d
-glucose (glucosamine) and 2-acetamido-2-deoxy-
d
-glucose (
N
-acetylglucosamine), but not 3-
O
-methyl-
d
-glucose or 2-deoxy-
d
-glucose into exopolymers. Incorporation was confirmed by gas chromatography with and without mass spectrometry, Fourier transform infrared, and
1
H nuclear magnetic resonance. The average molar percentage of glucosamine and
N
-acetylglucosamine in the exopolymers was about 18%.
Are the Enzyme Immunoassays for Antibodies to Pneumococcal Capsular Polysaccharides Serotype Specific?
Authors: Soininen Anu , van den Dobbelsteen Germie , Oomen Lukas , Käyhty Helena 
Published: July 2002

ABSTRACTThe specificity of antibody binding to pneumococcal capsular polysaccharides (Pnc PSs) measured by enzyme immunoassay (EIA) was studied by inhibition of antibody binding by homologous and heterologous PSs. We found extensive cross-reactivity of antibody binding to type 6B, 19F, and 23F PSs but not to type 14 PS, even after treatment with cell wall PS (CPS). The cross-reactive antibody was highly prevalent in sera of infants and adults with naturally acquired antibody, but not in sera of infants and adults immunized with pneumococcal vaccines. However, a type 11A antibody response was seen after vaccination with heterologous PSs. Monoclonal antibodies prepared against a type 6B PS-tetanus toxoid conjugate recognized also other than the specific type of PS in the EIA, implying the possible existence of a cross-reactive epitope. Remarkable differences in specificity among type 6B PS preparations from different manufacturers were found. Moreover, different lots of type 11A PS from the same manufacturer showed differences in specificity. The results suggest that some Pnc PS preparations may contain cross-reactive epitopes or impurities, other than CPS, that are common to many types of Pnc PS. The specificity of antibodies, especially in sera from nonimmunized subjects, measured by EIA can be questioned.
Lyme Borreliosis in Rhesus Macaques: Effects of Corticosteroids on Spirochetal Load and Isotype Switching of Anti-Borrelia burgdorferiAntibody
Authors: Pachner Andrew R. , Amemiya Kei , Bartlett Melanie , Schaefer Henry , Reddy Kiran , Zhang Wei-Fen 
Published: July 2002

ABSTRACTExperimentalBorrelia burgdorferiinfection of rhesus monkeys is an excellent model of Lyme disease and closely parallels the infection in humans. Little is known about the interaction of host immunity with the spirochete in patients with chronic infection. We hypothesized that rapid development of anti-B. burgdorferiantibody in immunocompetent nonhuman primates (NHPs) is the major determinant of the reduction of the spirochetal load in Lyme borreliosis. This hypothesis was tested by measurement of the spirochetal load by PCR in association with characterization of the anti-B. burgdorferihumoral immune response in immunocompetent NHPs versus that in corticosteroid-treated NHPs. Although anti-B. burgdorferiimmunoglobulin G (IgG) antibody was effectively inhibited in dexamethasone (Dex)-treated NHPs, anti-B. burgdorferiIgM antibody levels continued to rise after the first month and reached levels in excess of IgM levels in immunocompetent NHPs. This vigorous production of anti-B. burgdorferiIgM antibodies was also studied in vitro by measurement of antibody produced byB. burgdorferi-stimulated peripheral blood mononuclear cells. Despite these high IgM antispirochetal antibodies in Dex-treated NHPs, spirochetal loads were much higher in these animals. These data indicate that Dex treatment results in interference with isotype switching in this model and provide evidence that anti-B. burgdorferiIgG antibody is much more effective than IgM antibody in decreasing the spirochetal load in infected animals.