bluuebunny/crossref_metadata_2025_split huggingface dataset:
Wine Yeast Strains Engineered for Glycogen Overproduction Display Enhanced Viability under Glucose Deprivation Conditions
Authors: Pérez-Torrado R. , Gimeno-Alcañiz J. V. , Matallana E. 
Published: July 2002

ABSTRACT

We used metabolic engineering to produce wine yeasts with enhanced resistance to glucose deprivation conditions. Glycogen metabolism was genetically modified to overproduce glycogen by increasing the glycogen synthase activity and eliminating glycogen phosphorylase activity. All of the modified strains had a higher glycogen content at the stationary phase, but accumulation was still regulated during growth. Strains lacking
GPH1,
which encodes glycogen phosphorylase, are unable to mobilize glycogen. Enhanced viability under glucose deprivation conditions occurs when glycogen accumulates in the strain that overexpresses
GSY2
, which encodes glycogen synthase and maintains normal glycogen phosphorylase activity. This enhanced viability is observed under laboratory growth conditions and under vinification conditions in synthetic and natural musts. Wines obtained from this modified strain and from the parental wild-type strain don't differ significantly in the analyzed enological parameters. The engineered strain might better resist some stages of nutrient depletion during industrial use.
In Situ Transfer of Antibiotic Resistance Genes from Transgenic (Transplastomic) Tobacco Plants to Bacteria
Authors: Kay Elisabeth , Vogel Timothy M. , Bertolla Frank , Nalin Renaud , Simonet Pascal 
Published: July 2002

ABSTRACT

Interkingdom gene transfer is limited by a combination of physical, biological, and genetic barriers. The results of greenhouse experiments involving transplastomic plants (genetically engineered chloroplast genomes) cocolonized by pathogenic and opportunistic soil bacteria demonstrated that these barriers could be eliminated. The
Acinetobacter
sp. strain BD413, which is outfitted with homologous sequences to chloroplastic genes, coinfected a transplastomic tobacco plant with
Ralstonia solanacearum
and was transformed by the plant's transgene (
aadA
) containing resistance to spectinomycin and streptomycin. However, no transformants were observed when the homologous sequences were omitted from the
Acinetobacter
sp. strain. Detectable gene transfer from these transgenic plants to bacteria were dependent on gene copy number, bacterial competence, and the presence of homologous sequences. Our data suggest that by selecting plant transgene sequences that are nonhomologous to bacterial sequences, plant biotechnologists could restore the genetic barrier to transgene transfer to bacteria.
Distribution of Genes Encoding the Trypsin-Dependent Lantibiotic Ruminococcin A among Bacteria Isolated from Human Fecal Microbiota
Authors: Marcille F. , Gomez A. , Joubert P. , Ladiré M. , Veau G. , Clara A. , Gavini F. , Willems A. , Fons M. 
Published: July 2002

ABSTRACT

Fourteen bacterial strains capable of producing a trypsin-dependent antimicrobial substance active against
Clostridium perfringens
were isolated from human fecal samples of various origins (from healthy adults and children, as well as from adults with chronic pouchitis). Identification of these strains showed that they belonged to
Ruminococcus gnavus
,
Clostridium nexile
, and
Ruminococcus hansenii
species or to new operational taxonomic units, all from the
Clostridium coccoides
phylogenetic group. In hybridization experiments with a probe specific for the structural gene encoding the trypsin-dependent lantibiotic ruminococcin A (RumA) produced by
R. gnavus
, seven strains gave a positive response. All of them harbored three highly conserved copies of
rumA-
like genes. The deduced peptide sequence was identical to or showed one amino acid difference from the hypothetical precursor of RumA. Our results indicate that the
rumA
-like genes have been disseminated among
R. gnavus
and phylogenetically related strains that can make up a significant part of the human fecal microbiota.
Source of Enterococci in a Farmhouse Raw-Milk Cheese
Authors: Gelsomino R. , Vancanneyt M. , Cogan T. M. , Condon S. , Swings J. 
Published: July 2002

ABSTRACT

Enterococci are widely distributed in raw-milk cheeses and are generally thought to positively affect flavor development. Their natural habitats are the human and animal intestinal tracts, but they are also found in soil, on plants, and in the intestines of insects and birds. The source of enterococci in raw-milk cheese is unknown. In the present study, an epidemiological approach with pulsed-field gel electrophoresis (PFGE) was used to type 646
Enterococcus
strains which were isolated from a Cheddar-type cheese, the milk it was made from, the feces of cows and humans associated with the cheese-making unit, and the environment, including the milking equipment, the water used on the farm, and the cows' teats. Nine different PFGE patterns, three of
Enterococcus casseliflavus
, five of
Enterococcus faecalis
, and one of
Enterococcus durans
, were found. The same three clones, one of
E. faecalis
and two of
E. casseliflavus
, dominated almost all of the milk, cheese, and human fecal samples. The two
E. casseliflavus
clones were also found in the bulk tank and the milking machine even after chlorination, suggesting that a niche where enterococci could grow was present and that contamination with enterococci begins with the milking equipment. It is likely but unproven that the enterococci present in the human feces are due to consumption of the cheese. Cow feces were not considered the source of enterococci in the cheese, as
Enterococcus faecium
and
Streptococcus bovis
, which largely dominated the cows' intestinal tracts, were not found in either the milk or the cheese.
Lactobacillus caseiIs Able To Survive and Initiate Protein Synthesis during Its Transit in the Digestive Tract of Human Flora-Associated Mice
Authors: Oozeer R. , Goupil-Feuillerat N. , Alpert C. A. , van de Guchte M. , Anba J. , Mengaud J. , Corthier G. 
Published: July 2002

ABSTRACTLiveLactobacillus caseiis present in fermented dairy products and has beneficial properties for human health. In the human digestive tract, the resident flora generally prevents the establishment of ingested lactic acid bacteria, the presence of which is therefore transient. The aim of this work was to determine ifL. caseiDN-114 001 survives during transit and how this bacterium behaves in the digestive environment. We used the human flora-associated (HFA) mouse model.L. caseiDN-114 001 was genetically modified by the introduction ofermandluxgenes, encoding erythromycin resistance and luciferase, respectively. For this modified strain (DN-240 041), light emission related to luciferase expression could easily be detected in the contents of the digestive tract. When inoculated into the digestive tract of HFA mice,L. casei(DN-240 041) survives but is eliminated with the same kinetics as an inert transit marker, indicating that it does not establish itself. In pure culture ofL. casei, luciferase activities were high in the exponential and early stationary growth phases but decreased to become undetectable 1 day after inoculation. Viability was only slightly reduced even after more than 5 days. After transit in HFA mice, luciferase activity was detected even when 5-day-oldL. caseicultures were given to the mice. In culture, the luciferase activity could be restored after 0.5 to 7 h of incubation in fresh medium or milk containing glucose, unless protein synthesis was inhibited by the addition of chloramphenicol or rifampin. These results suggest that in HFA miceL. caseiDN-240 041, and thus probablyL. caseiDN-114 001, is able to initiate new protein synthesis during its transit with the diet. The beneficial properties ofL. casei-fermented milk for human health might be related to this protein synthesis in the digestive tract.
Phylogenetic Relationships and Coaggregation Ability of Freshwater Biofilm Bacteria
Authors: Rickard Alex H. , Leach Stephen A. , Hall Laurence S. , Buswell Clive M. , High Nicola J. , Handley Pauline S. 
Published: July 2002

ABSTRACT

Nineteen numerically dominant heterotrophic bacteria from a freshwater biofilm were identified by 16S ribosomal DNA gene sequencing, and their coaggregation partnerships were determined. Phylogenetic trees showed that both distantly related and closely related strains coaggregated at intergeneric, intrageneric, and intraspecies levels. One strain,
Blastomonas natatoria
2.1, coaggregated with all 18 other strains and may function as a bridging organism in biofilm development.
Cloning of a Gene Encoding Raw-Starch-Digesting Amylase from a
Cytophaga
sp. and Its Expression in
Escherichia coli
Authors: Jeang Chii-Ling , Chen Li-Shien , Chen Ming-Yu , Shiau Rong-Jen 
Published: July 2002

ABSTRACT

A raw-starch-digesting amylase (RSDA) gene from a
Cytophaga
sp. was cloned and sequenced. The predicted protein product contained 519 amino acids and had high amino acid identity to α-amylases from three
Bacillus
species. Only one of the
Bacillus
α-amylases has raw-starch-digesting capability, however. The RSDA, expressed in
Escherichia coli
, had properties similar to those of the enzyme purified from the
Cytophaga
sp.
Responses of Adipose and Muscle Lipoprotein Lipase to Chronic Infection and Subsequent Acute Lipopolysaccharide Challenge
Authors: Picard Frédéric , Arsenijevic Denis , Richard Denis , Deshaies Yves 
Published: July 2002

ABSTRACT

Infection of male Swiss Webster mice with
Toxoplasma gondii
or
Neospora caninum
leads to long-term alterations in energy balance. Following an initial 20 to 30% weight loss in all
T. gondii
-infected mice, half of the animals regain most of the lost weight (gainers), whereas the others maintain their low body weight (nongainers). Infection with
N. caninum
does not elicit weight loss. Lipoprotein lipase (LPL), the enzyme responsible for plasma triglyceride (TG) clearance and partitioning among tissues, is under tissue-specific modulation associated with energy balance. It is also a major determinant of infection-induced hypertriglyceridemia. This study aimed to assess the long-term modulation of adipose and muscle LPL activity in mice infected with
T. gondii
or
N. caninum
, to evaluate the effects of subsequent acute lipopolysaccharide (LPS) administration, and to relate LPL modulation in these conditions with infection-related changes in body weight gain. Twenty-eight days after infection, LPL activity in muscle of both gainer and nongainer
T. gondii
-infected mice was reduced by 40 to 50% compared with the levels in controls and
N. caninum
-infected mice, whereas LPL activity in adipose depots remained unchanged in all infected groups compared to the level in controls. LPS (from
Escherichia coli
, 100 ng/kg) injection induced a global reduction in adipose LPL in all groups, as assessed 90 min later. In both
T. gondii
-infected subgroups, muscle LPL was not further reduced by LPS treatment, whereas it was decreased by 40 to 50% in muscles of control and
N. caninum
-infected mice. Pre-LPS TG levels in plasma were similar in all groups. LPS greatly increased TG levels in plasma in both control and
N. caninum
-infected animals, whereas it did not alter those of
T. gondii
-infected gainer or nongainer animals. These results show that (i) independently of the extent of postinfection weight gain, long-term infection with
T. gondii
chronically reduces muscle LPL, which becomes unresponsive to acute endotoxemia; (ii) modulation of tissue LPL activity during chronic
T. gondii
infection favors TG partitioning towards adipose tissue; and (iii) skeletal muscle LPL is a key determinant of the acute response of triglyceridemia to LPS.
Interleukin-18 Induces Acute Biphasic Reduction in the Levels of Circulating Leukocytes in Mice
Authors: Hosohara Katsushi , Ueda Haruyasu , Kashiwamura Shin-Ichiro , Yano Takako , Ogura Takeharu , Marukawa Seishiro , Okamura Haruki 
Published: July 2002

ABSTRACTWe investigated the acute hematological changes caused by interleukin-18 (IL-18) in mice. Intraperitoneal administration of IL-18 (2 μg/mouse) resulted in biphasic decreases in the number of leukocytes in the blood. The first phase of decrease occurred within 2 h of IL-18 administration and was followed by a transient increase at 5 h. The second phase of decrease occurred at around 6 h, reaching a nadir which lasted for more than 24 h. In mice deficient in inducible nitric oxide (NO) synthase, the first phase of reduction of leukocytes did not occur although the second phase of decrease was observed. In mice deficient in gamma interferon (IFN-γ) or in mice depleted of natural killer cells and incapable of producing IFN-γ, IL-18 had no effect on the number of circulating leukocytes. Levels of nitrite and/or nitrate in the serum were elevated within 2 h after administration of IL-18, reaching a peak at 4 h and then decreasing gradually to the basal level over a 24-h period of time. On the other hand, serum IFN-γ levels changed in a biphasic manner, reaching a peak at 2 h after IL-18 administration, followed by a decrease in the basal level and a second increase at 6 h. Levels of IL-18 receptor mRNAs also showed biphasic changes in correlation with the changes in serum IFN-γ levels. These results suggest that the changes in the leukocyte number following IL-18 administration are mediated by NO and IFN-γ, with NO being involved in the first phase of reduction and IFN-γ being involved in both phases.
Regulation of Interleukin-8 by Interleukin-10 and Transforming Growth Factor β in Human Monocytes Infected withMycobacterium bovis
Authors: Méndez-Samperio Patricia , García Elizabeth , Vázquez Abraham , Palma Janet 
Published: July 2002

ABSTRACTRecent studies indicate that interleukin 8 (IL-8) production contributes to the host immune responses against mycobacterial infection. In this study, we were interested to determine whether induction of IL-8 in human monocytes infected withMycobacterium boviswas regulated by other monocyte-derived cytokines important in antimycobacterial immunity: IL-10 and transforming growth factor β (TGF-β). Here, we report that IL-10 reduced, in a graded and significant manner, IL-8 production byM. bovis-infected human monocytes. Additionally, the specificity of the observed inhibition was further confirmed, since the addition of an anti-IL-10 neutralizing antibody completely reversed the inhibitory effect. In contrast, addition or neutralization of TGF-β appeared to have no significant effect onM. bovis-induced IL-8 secretion by human monocytes, whereas CD40 expression onM. bovis-infected monocytes was significantly inhibited by this cytokine. This was consistent with the finding by the reverse transcription-PCR method that pretreatment with IL-10, but not TGF-β, potently inhibited IL-8 mRNA levels. Interestingly, neutralization of endogenous IL-10 did not significantly alter IL-8 secretion, suggesting that induction of IL-8 was not significantly affected by coexpression of IL-10 during infection of human monocytes withM. bovis.Collectively, these data indicate that IL-8 production may be regulated when human monocytes are exposed to IL-10 prior to activation withM. bovisBCG. These data will aid in our understanding of the mechanisms involved in regulating the protective immune response to stimulation withM. bovisBCG.
Performance of Three Microimmunofluorescence Assays for Detection of
Chlamydia pneumoniae
Immunoglobulin M, G, and A Antibodies
Authors: Bennedsen Mette , Berthelsen Lene , Lind Inga 
Published: July 2002

ABSTRACT

The microimmunofluorescence (MIF) test is considered the “gold standard” for laboratory diagnosis of acute and chronic
Chlamydia pneumoniae
infection. The performance of a MIF test based on
C. pneumoniae
antigen from Washington Research Foundation (WRF) was compared with those of assays from Labsystems (LAB) and MRL Diagnostics (MRL) by investigation of sera from three groups of patients: group I, 83 sera from 28 patients with atypical pneumonia; group II, 37 sera from 16 patients with acute
C. pneumoniae
or
Chlamydia psittaci
respiratory tract infection confirmed by PCR or culture; group III, 100 sera from 100 persons enrolled in the Copenhagen City Heart Study. The accordance among the results of the WRF assay and the two commercial assays was excellent for the immunoglobulin M (IgM) antibody detection rate (98%). The accordance in detection rates for IgG and IgA antibodies in sera from patients with acute infections was acceptable (87 and 88%), and in sera from group III, it was excellent (95 and 97%). The determinations of endpoint titers were reproducible with <1 dilution step difference for all three methods, except that the mean IgM antibody titer found by the LAB assay was almost 2 dilution steps higher than that found by the other two methods. Although the three assays use different
C. pneumoniae
strains as antigens, the detection rates and IgG and IgA endpoint titers were similar. The difference in endpoint titers of IgM antibodies is of no major concern, as the diagnosis of acute
C. pneumoniae
infection rests on the presence of IgM antibodies, not on their level.
Bactericidal Activity in Whole Blood as a Potential Surrogate Marker of Immunity after Vaccination against Tuberculosis
Authors: Cheon Seon-Hee , Kampmann Beate , Hise Amy G. , Phillips Manijeh , Song Ho-Yeon , Landen Katherine , Li Qing , Larkin Rhonda , Ellner Jerrold J. , Silver Richard F. , Hoft Daniel F. , Wallis Robert S. 
Published: July 2002

ABSTRACTThe development of new tuberculosis (TB) vaccines will require the identification of correlates of human protection. This study examined the balance between immunity and virulence in a whole blood infection model in which intracellular mycobacterial survival was measured using BACTEC. In the blood of tuberculin-negative donors, counts ofMycobacterium tuberculosisH37Ra organisms fell by 0.14 log10CFU during 96 h of whole blood culture, whereas counts ofMycobacterium bovisBCG,M. tuberculosisH37Rv, and a clinical TB isolate's organisms increased by 0.13, 0.43, and 1.04 log10CFU, respectively (P< 0.001), consistent with their relative virulence. Inhibition of tumor necrosis factor alpha by the addition of methylprednisolone or pentoxifylline or removal of CD4+or CD8+T cells by magnetic beads had deleterious effects on immune control of intracellular growth only in the blood of tuberculin-positive donors. Repeated vaccination of eight tuberculin-negative volunteers withM. bovisBCG resulted in a 0.3 log (50%) reduction in BCG CFU counts in the model compared to baseline values (P< 0.05). Three of the volunteers responded only after the second vaccination. These experiments indicate that whole blood culture may be used to measure immunity toM. tuberculosisand that further studies of repeated BCG vaccination are warranted.
Cultivation of
Plasmodium
spp
Authors: Schuster Frederick L. 
Published: July 2002

SUMMARY

Cultivation of both human and non-human species of
Plasmodium
spp., the causal agent of malaria, has been a major research success, leading to a greater understanding of the parasite. Efforts at cultivating the organisms in vitro are complicated by the parasites' alternating between a human host and an arthropod vector, each having its own set of physiological, metabolic, and nutritional parameters. Life cycle stages of the four species that infect humans have been established in vitro. Of these four,
P. falciparum
remains the only species for which all stages have been cultured in vitro; different degrees of success have been achieved with the other human
Plasmodium
spp. The life cycle includes the exoerythrocytic stage (within liver cells), the erythrocytic stage (within erythrocytes or precursor reticulocytes), and the sporogonic stage (within the vector). Culture media generally consist of a basic tissue culture medium (e.g., minimal essential medium or RPMI 1640) to which serum and erythrocytes are added. Most of the efforts have been directed toward the stage found in the erythrocyte. This stage has been cultivated in petri plates or other growth vessels in a candle jar to generate elevated CO
2
levels or in a more controlled CO
2
atmosphere. Later developments have employed continuous-flow systems to reduce the labor-intensive nature of medium changing. The exoerythrocytic and sporogonic life cycle stages have also been cultivated in vitro. A number of avian, rodent, and simian malarial parasites have also been established in vitro. Although cultivation is of great help in understanding the biology of
Plasmodium
, it does not lend itself to use for diagnostic purposes.
In Vitro Cultivation of Microsporidia of Clinical Importance
Authors: Visvesvara Govinda S. 
Published: July 2002

SUMMARY

Although attempts to develop methods for the in vitro cultivation of microsporidia began as early as 1937, the interest in the culture of these organisms was confined mostly to microsporidia that infect insects. The successful cultivation in 1969 of
Encephalitozoon cuniculi
, a microsporidium of mammalian origin, and the subsequent identification of these organisms as agents of human disease heightened interest in the cultivation of microsporidia. I describe the methodology as well as the cell lines, the culture media, and culture conditions used in the in vitro culture of microsporidia such as
Brachiola (Nosema) algerae, Encephalitozoon cuniculi, E. hellem, E. intestinalis, Enterocytozoon bieneusi, Trachipleistophora hominis,
and
Vittaforma corneae
that cause human disease.
Roles of p38 Mitogen-Activated Protein Kinase, NF-κB, and Protein Kinase C in Proinflammatory Cytokine mRNA Expression by Human Peripheral Blood Leukocytes, Monocytes, and Neutrophils in Response toAnaplasma phagocytophila
Authors: Kim Hyung-Yong , Rikihisa Yasuko 
Published: July 2002

ABSTRACTAnaplasma phagocytophila, an obligately intracellular bacterium of granulocytes, causes human granulocytic ehrlichiosis. Within 2 h after addition ofA. phagocytophila, interleukin-1β (IL-1β), tumor necrosis factor alpha (TNF-α), and IL-6 mRNAs are induced in human peripheral blood leukocytes (PBLs) or monocytes in vitro. However, neutrophils generate only IL-1β mRNA. In the present study, signaling pathways for induction of these three cytokines were examined. TNF-α and IL-6 mRNA expression by PBLs was inhibited with SB 203580 (a p38 mitogen-activated protein kinase [MAPK] inhibitor), MG-132 (a proteasome inhibitor), and SN-50 (an NF-κB inhibitor). Activation of p38 MAPK and NF-κB mRNAs in monocytes was detectable within 15 to 30 min after addition ofA. phagocytophila. Expression of these two cytokine mRNAs in PBLs and monocytes was also dependent on protein kinase C (PKC), protein kinase A (PKA), and protein tyrosine kinase (PTK). IL-1β mRNA expression by neutrophils was not dependent on p38 MAPK, and p38 MAPK was not activated in neutrophils incubated withA. phagocytophila. IL-1β mRNA induction by PBLs, monocytes, and neutrophils was dependent on PKC and PKA. Neutrophil expression of IL-1β mRNA was dependent on transglutaminase, phospholipase C, and PTK, all of which are also required for internalization ofA. phagocytophila. However, monocyte expression of IL-1β mRNA was less dependent on these enzymes. These results suggest thatA. phagocytophilatransduces different signals between its host neutrophils and monocytes for proinflammatory cytokine generation.