bluuebunny/crossref_metadata_2025_split huggingface dataset:
Trophic cascades: the primacy of trait‐mediated indirect interactions
Authors: Schmitz Oswald J. , Krivan Vlastimil , Ovadia Ofer 
Published: December 2004

AbstractTrophic cascades are textbook examples of predator indirect effects on ecological systems. Yet there is considerable debate about their nature, strength and overall importance. This debate stems in part from continued uncertainty about the ultimate mechanisms driving cascading effects. We present a synthesis of empirical evidence in support of one possible ultimate mechanism: the foraging‐predation risk trade‐offs undertaken by intermediary species. We show that simple trade‐off behaviour can lead to both positive and negative indirect effects of predators on plant resources and hence can explain considerable contingency on the nature and strength of cascading effects among systems. Thus, predicting the sign and strength of indirect effect simply requires knowledge of habitat and resource use by prey with regard to predators’ presence, habitat use and hunting mode. The synthesis allows us to postulate a hypothesis for new conceptualization of trophic cascades which is to be viewed as an ultimate trade‐off between intervening species. In this context, different predators apply different rules of engagement based on their hunting mode and habitat use. These different rules then determine whether behavioural effects persist or attenuate at the level of the food chain.
Attraction of willow warblers to sawfly‐damaged mountain birches: novel function of inducible plant defences?
Authors: Mäntylä Elina , Klemola Tero , Haukioja Erkki 
Published: December 2004

AbstractPlants wounded by invertebrate herbivores emit volatile compounds which invertebrate predators and parasitoids can utilize in locating herbivore prey or hosts. We studied the possibility that an analogical phenomenon might operate between plants and avian insectivores. We show that foliar damage by sawfly larvae on the mountain birch led a passerine bird (willow warbler) to prefer intact branches from trees with introduced larvae over intact branches from control trees. Besides olfaction, the UV vision of birds offers a possible mechanism, as some herbivore‐inducible leaf compounds, e.g. surface flavonoids, have UV spectral maxima well within the range of birds’ UV vision.
Integrated regulation in response to aromatic compounds: from signal sensing to attractive behaviour
Authors: Shingler Victoria 
Published: December 2004

SummaryDeciphering the complex interconnecting bacterial responses to the presence of aromatic compounds is required to gain an integrated understanding of how aromatic catabolic processes function in relation to their genome and environmental context. In addition to the properties of the catabolic enzymes themselves, regulatory responses on at least three different levels are important. At a primary level, aromatic compounds control the activity of specific members of many families of transcriptional regulators to direct the expression of the specialized enzymes for their own catabolism. At a second level, dominant global regulation in response to environmental and physiological cues is incorporated to subvert and couple transcription levels to the energy status of the bacteria. Mediators of these global regulatory responses include the alarmone (p)ppGpp, the DNA‐bending protein IHF and less well‐defined systems that probably sense the energy status through the activity of the electron transport chain. At a third level, aromatic compounds can also impact on catabolic performance by provoking behavioural responses that allow the bacteria to seek out aromatic growth substrates in their environment.
Temporal dynamics and degradation activity of an bacterial inoculum for treating waste metal‐working fluid
Authors: Van Der Gast Christopher J. , Whiteley Andrew S. , Thompson Ian P. 
Published: December 2004

SummaryIn order for established bioreactors to be effective for treating chemically mixed wastes such as metal working fluids (MWF) it is essential that they harbour microbial populations that can maintain sufficient active biomass and degrade each of the chemical constituents present. In this study we investigated the effectiveness of a bacterial consortium composed of four species (Clavibacter michiganensis, Methylobacterium mesophilicum, Rhodococcus erythropolis and Pseudomonas putida), assembled on the basis of their apparent ubiquity in waste MWF, degradation ability and tolerance to fluctuating chemistry of the waste. The temporal dynamics of the inoculum and its effects on the fate of individual chemical components of the waste were studied, by regular sampling, over 400 h. Using a complementary approach of culture with chemotaxonomic (FAME) analysis and applying group specific probes (FISH), the inoculum was found to represent a significant component of the community in bioreactors with and without presence of indigenous MWF populations. In addition, the reduction in the COD by the consortium was approximately 85% of the total pollution load, and 30–40% more effectively than any other treatment (indigenous MWF community alone or activated sludge). Furthermore, all the chemical constituents, including the biocide (a formaldehyde release agent) demonstrated > 60% reduction. Many chemical components of the MWF proved to be recalcitrant in the other treatments. The results of this study confirm that assemblage of an inoculum, based on a comprehensive knowledge of the indigenous microbial community, in the target habitat, is a highly effective way of selecting microbial populations for bioaugmentation of bioreactors.
Isolation and properties of methanesulfonate‐degrading Afipia felis from Antarctica and comparison with other strains of A. felis
Authors: Moosvi S. Azra , Pacheco Catarina C. , McDonald Ian R. , De Marco Paolo , Pearce David A. , Kelly Donovan P. , Wood Ann P. 
Published: December 2004

SummaryThree novel strains of methylotrophic Afipia felis were isolated from several locations on Signy Island, Antarctica, and a fourth from estuary sediment from the River Douro, Portugal. They were identified as strains of the α‐2 proteobacterium A. felis by 16S rRNA gene sequence  analysis.  Two  strains  tested  were  shown to contain the fdxA gene, diagnostic for A. felis. All strains grew with methanesulfonate (and two strains with dimethylsulfone) as sole carbon substrate. Growth on methanesulfonate required methanesulfonate monooxygenase (MSAMO), using NADH as the reductant and stimulated by reduced flavin nucleotides and Fe(II). Polymerase chain reaction amplification of DNA from an Antarctic strain showed a typical msmA gene for the α‐hydroxylase of MSAMO, and both Antarctic and Portuguese strains contained mxaF, the methanol dehydrogenase large subunit gene. This is the first report of methanesulfonate‐degrading bacteria from the Antarctic and of methylotrophy in Afipia, and the first description of any bacterium able to use both methanesulfonate and dimethylsulfone. In contrast, the type strain of A. felis DSM 7326T was not methylotrophic, but grew in defined mineral medium with a wide range of single simple organic substrates. Free‐living Afipia strains occurring widely in the natural environment may be significant as methylotrophs, degrading C1‐sulfur compounds, including the recalcitrant organosulfur compound methanesulfonate.
Actinide and metal toxicity to prospective bioremediation bacteria
Authors: Ruggiero Christy E. , Boukhalfa Hakim , Forsythe Jennifer H. , Lack Joseph G. , Hersman Larry E. , Neu Mary P. 
Published: December 2004

SummaryBacteria may be beneficial for alleviating actinide contaminant migration through processes such as bioaccumulation or metal reduction. However, sites with radioactive contamination often contain multiple additional contaminants, including metals and organic chelators. Bacteria‐based bioremediation requires that the microorganism functions in the presence of the target contaminant, as well as other contaminants. Here, we evaluate the toxicity of actinides, metals and chelators to two different bacteria proposed for use in radionuclide bioremediation, Deinococcus radiodurans and Pseudomonas putida, and the toxicity of Pu(VI) to Shewanella putrefaciens. Growth of D. radiodurans was inhibited at metal concentrations ranging from 1.8 µM Cd(II) to 32 mM Fe(III). Growth of P. putida was inhibited at metal concentrations ranging from 50 µM Ni(II) to 240 mM Fe(III). Actinides inhibited growth at mM concentrations: chelated Pu(IV), U(VI) and Np(V) inhibit D. radiodurans growth at 5.2, 2.5 and 2.1 mM respectively. Chelated U(VI) inhibits P. putida growth at 1.7 mM, while 3.6 mM chelated Pu(IV) inhibits growth only slightly. Pu(VI) inhibits S. putrefaciens growth at 6 mM. These results indicate that actinide toxicity is primarily chemical (not radiological), and that radiation resistance does not ensure radionuclide tolerance. This study also shows that Pu is less toxic than U and that actinides are less toxic than other types of metals, which suggests that actinide toxicity will not impede bioremediation using naturally occurring bacteria.
Tuber magnatum Pico, a species of limited geographical distribution: its genetic diversity inside and outside a truffle ground
Authors: Mello Antonietta , Murat Claude , Vizzini Alfredo , Gavazza Virgilio , Bonfante Paola 
Published: December 2004

SummaryThe aim of this work was to clarify the genetic structure of the ectomycorrhizal fungus, Tuber magnatum Pico, in a natural truffle ground located in north Italy. Ascomata of this population of T. magnatum were collected over a period of up to 5 years. For comparative analysis, T. magnatum fruit bodies of different geographical origin were also considered. We used single locus markers, such as the variable region of ribosomal genes (ITS), the β‐tubulin gene and sequence‐characterized amplified regions (SCAR), as tools to identify single‐nucleotide polymorphisms (SNPs). On the basis of the molecular results, which were indirectly supported by a karyological analysis, a self‐fertilization mechanism is suggested. A SCAR region was polymorphic within the samples of the truffle ground, leading to the identification of two genotypes. In addition, both the SCAR and the ITS proved to be polymorphic among samples coming from different geographical regions, revealing a genetic differentiation in T. magnatum.
Assessing terminal restriction fragment length polymorphism suitability for the description of bacterial community structure and dynamics in hydrocarbon‐polluted marine environments
Authors: Denaro R. , D’Auria G. , Di Marco G. , Genovese M. , Troussellier M. , Yakimov M. M. , Giuliano L. 
Published: December 2004

SummaryThe distribution of bacterial communities terminal restriction fragment length polymorphism (T‐RFLP) fingerprint patterns was evaluated at three proximal hydrocarbon‐contaminated sites located within the harbour of Messina. In order to analyse the short‐term variability of the individual terminal restriction fragment (T‐RF) patterns, water samples were collected at the three sites on three occasions within 3 months (T0, T90 and T91). Four sample sizes, from 50 to 1000 ml for each collected sample, were analysed separately (36 total analysed samples) to evaluate the relationship between the sample size and the bacterial diversity estimates. The dominant T‐RF groups mostly belonged to signatures of putative hydrocarbon‐degrading bacteria, as revealed by the virtual analysis of the obtained bands. In order to test whether significant differences were occurring between the analysed samples, the Kruskal–Wallis non‐parametric test was applied to the T‐RF data set. Neither significant influence of the sample size nor short spatial variability within the three sampled sites was detected for each sampling time. On the contrary, significant temporal changes in the diversity of the bacterial communities were observed. These results were confirmed by the non‐metric multidimensional scales (nMDS) analysis of the whole set of samples, which indicated three main groups corresponding to the three different sampling times. In summary, the T‐RFLP technique, although a polymerase chain reaction‐based method, proved to be a suitable technique for monitoring polluted marine environments, typically characterized by low diversity and high relative abundances of a few dominant groups.
Thermal destruction of dried vegetative yeast cells and dried bacterial spores in a convective hot air flow: strong influence of initial water activity
Authors: Fine Frédéric , Gervais Patrick 
Published: December 2004

SummaryThermal treatment of Bacillus subtilis spores and Saccharomyces cerevisiae cells dried on glass beads was performed at various initial water activities (in the range 0.10–0.90). Experiments were carried out at 150°C, 200°C and 250°C for 5–120 s. Significant destruction of up to 107 vegetative cells and up to 105 spores g−1 was achieved, depending upon treatment conditions. This study demonstrated that the initial water activity (aw) value of a sample is very important in the destruction or survival of microorganisms treated with hot air stresses. As described previously, the heat resistance of spores and vegetative cells was strongly enhanced by low initial aw values until an optimal aw value between 0.30 and 0.50, with maximal viability at 0.35 for both S. cerevisiae and B. subtilis. However, our results highlighted for the first time that very low initial aw values (close to 0.10) greatly improved the destruction of spores and vegetative cells. Factors and possible mechanisms involved in the death of vegetative cells and spores are discussed.
Activity‐Responsive Pacing Produces Long‐Term Heart Rate Variability
Authors: RAJ SATISH R. , ROACH DANIEL E. , KOSHMAN MARY‐LOU , SHELDON ROBERT S. 
Published: December 2004

Introduction: Long‐term heart rate variability (HRV) measures, including the standard deviation of means of successive 5‐minute epochs of R‐R interval intervals (SDANN) and the power law slope (β), are important prognostic measures, yet their physiologic basis is unknown. We tested the hypothesis that long‐term HRV arises from physical activity in a randomized cross‐over study in patients with rate‐responsive pacemakers. Methods and Results: Ten patients with complete heart block and dual‐chamber pacemakers underwent 24‐hour periods of ambulatory ECG in each of three pacing modes: atrially tracked, fixed‐rate, and rate‐responsive pacing. SDANN, ultralow frequency (ULF; frequencies <0.0033 Hz), and β slope were calculated; and high‐frequency power and root mean square of consecutive normal R‐R intervals (rMSSD) were calculated as measures of short‐term HRV, which have autonomic origins. Long‐term HRV measures were similar with atrially tracked and rate‐responsive pacing and were much greater than in fixed‐rate pacing (SDANN P = 0.0001; ULF P = 0.0001; β slope P = 0.0002). Short‐term HRV measures were similarly low in fixed‐rate and rate‐responsive pacing (P = NS) and were significantly lower than with atrially tracked pacing (P = 0.0034). Conclusion: Rate‐responsive pacing reproduces long‐term, but not short‐term, measures of HRV, suggesting that they may be markers of heart rate responses to patient activity. (J Cardiovasc Electrophysiol, Vol. 15, pp. 179‐183, February 2004)
Buthionine Sulfoximine Increases the Toxicity of Nifurtimox and Benznidazole toTrypanosoma cruzi
Authors: Faundez Mario , Pino Laura , Letelier Paula , Ortiz Carla , López Rodrigo , Seguel Claudia , Ferreira Jorge , Pavani Mario , Morello Antonio , Maya Juan Diego 
Published: December 2004

ABSTRACTl-Buthionine (S,R)-sulfoximine (BSO) increased the toxicity of nifurtimox and benznidazole toward the epimastigote, trypomastigote, and amastigote forms ofTrypanosoma cruzi. BSO at 500 μM decreased total glutathione-derived thiols by 70 to 80% in 48 h. In epimastigotes, 500 μM BSO decreased the concentration of nifurtimox needed to inhibit constant growth of the parasites by 50%, from 14.0 to 9.0 μM, and decreased that of benznidazole from 43.6 to 24.1 μM. The survival of epimastigotes or trypomastigotes treated with nifurtimox or benznidazole, as measured by MTT [3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide) reduction, was significantly decreased by 500 μM BSO. In Vero cells infected with amastigotes, 25 μM BSO was able to potentiate the effect of nifurtimox and benznidazole as measured by the percentage of infected Vero cells multiplied by the average number of intracellular amastigotes (endocytic index). At 0.5 μM nifurtimox, the proportion of Vero cells infected decreased from 27 to 20% and the endocytic index decreased from 2,500 to 980 when 25 μM BSO was added. Similar results were obtained with benznidazole- and BSO-benznidazole-treated cells. This study indicates that potentiation of nifurtimox or benznidazole by BSO could decrease the clinical dose of both drugs and diminish the side effects or the length of therapy.
Effects of Root Extracts of
Fagara zanthoxyloides
on the In Vitro Growth and Stage Distribution of
Plasmodium falciparum
Authors: Kassim Olakunle O. , Loyevsky Mark , Elliott Biaffra , Geall Andrew , Amonoo Henrietta , Gordeuk Victor R. 
Published: December 2004

ABSTRACT

The development of resistance by
Plasmodium falciparum
to conventional drugs poses a threat to malaria control. There is therefore a need to find new, effective, and affordable remedies for malaria, including those derived from plants. This study demonstrates that crude, reverse-phase high-pressure liquid chromatography (RP-HPLC)-semipurified, and RP-HPLC-purified root extracts of
Fagara zanthoxyloides
inhibit the growth of
P. falciparum
in vitro, with 50% inhibitory concentrations (IC
50
s) of 4.90, 1.00, and 0.13 μg/ml, respectively. Roots of
F. zanthoxyloides
, known as chewing sticks, are widely used for tooth cleaning in West Africa. Microscopic examination of Giemsa-stained slides showed a virtual absence of schizonts in ring-stage synchronized cultures treated with crude extracts at concentrations of 30 to 60 μg/ml during 36 to 48 h of incubation. These observations suggest that the active constituent in the extract may be cytotoxic for
P. falciparum
trophozoites, thereby inhibiting their development to the schizont stage. A pure bioreactive fraction was subsequently obtained from the chromatographic separations. When this fraction was mixed with pure fagaronine, the mixture coeluted as a single peak on the analytical RP-HPLC column, suggesting that fagaronine may be the active antimalarial constituent of
Fagara
root extracts. Additional experiments showed that fagaronine also inhibited
P. falciparum
growth, with an IC
50
of 0.018 μg/ml. The results of this study suggest that the antimalarial activity of fagaronine deserves further investigation.
In Vitro Activities of Novel 2-Fluoro-Naphthyridine-Containing Ketolides
Authors: Abbanat Darren , Webb Glenda , Foleno Barbara , Li Y. , Macielag Mark , Montenegro Deborah , Wira Ellyn , Bush Karen 
Published: December 2004

ABSTRACT

In vitro activities of erythromycin A, telithromycin, and two investigational ketolides, JNJ-17155437 and JNJ-17155528, were evaluated against clinical bacterial strains, including selected common respiratory tract pathogens. Against 46 macrolide-susceptible and -resistant
Streptococcus pneumoniae
strains, the MIC
90
(MIC at which 90% of the isolates tested were inhibited) of the investigational ketolides was 0.25 μg/ml, twofold lower than that of telithromycin and at least 64-fold lower than that of erythromycin A. Against
erm
(B)-containing pneumococci, the MIC
90
of all the ketolides was 0.06 μg/ml. The MIC
90
of the investigational ketolides against
mef
(A)-containing pneumococci or pneumococci with both
mef
(A) and
erm
(B) was 0.25 μg/ml, two-and fourfold lower, respectively, than that of telithromycin. In contrast, the MICs of the investigational ketolides against macrolide-resistant
S. pneumoniae
strains with ribosomal mutations were similar to or, in some cases, as much as eightfold higher than those of telithromycin. Against
Haemophilus influenzae
, MICs of all the ketolides were ≤2 μg/ml. Against three
Moraxella catarrhalis
isolates, the MIC of the ketolides was 0.25 μg/ml. The ketolides inhibited in vitro protein synthesis, with 50% inhibitory concentrations ranging from 0.23 to 0.27 μM. In time-kill studies against macrolide-susceptible and
erm
- or
mef
-containing pneumococci, the ketolides were bacteriostatic to slowly bactericidal, with 24-h log
10
decreases ranging from 2.0 to 4.1 CFU. Intervals of postantibiotic effects for the ketolides against macrolide-susceptible and -resistant
S. pneumoniae
were 3.0 to 8.1 h.
Differences in the
Enterococcus faecalis lsa
Locus That Influence Susceptibility to Quinupristin-Dalfopristin and Clindamycin
Authors: Singh Kavindra V. , Murray Barbara E. 
Published: December 2004

ABSTRACT

We have previously shown that the
Enterococcus faecalis lsa
gene, encoding the putative ABC protein Lsa, influences resistance to quinupristin-dalfopristin (Q-D) and clindamycin (CLI). We have now found that, while cloned
lsa
from
E. faecalis
strain V583 (
lsa
V
) fully restored resistance to Q-D, CLI, and dalfopristin (DAL) lost by the OG1
lsa
disruption mutant TX5332 and also caused increased MICs for
Lactococcus lactis
LM2301, cloned
lsa
from OG1 (
lsa
OG
) did not cause any increase in MICs for either species. Sequencing of ca. 2 kb of these two
lsa
alleles found differences between
lsa
OG
and
lsa
V
in the upstream region as well as in the 5′ and 3′ halves of the
lsa
gene. To investigate the reason for the phenotypic differences expressed by the two cloned loci, 5′ half plus 3′ half hybrid constructs were created. When introduced into both TX5332 and
L. lactis
, cloned
lsa
V5
′
OG3
′
conferred increases in MICs of Q-D, CLI, and DAL similar to those of cloned
lsa
V
while cloned
lsa
OG5
′
V3
′
showed a moderate increase in MICs relative to those of
lsa
OG
, indicating that both halves of the locus can influence resistance expression. After site-directed mutagenesis of the cloned
lsa
alleles at positions −131 and −133 (relative to the putative Lsa start codon ATG), which converted two A's of
lsa
V
to the G and T of
lsa
OG
and vice versa, MIC testing showed that mutagenized
lsa
OG
(
lsa
OG-M
) was strongly influenced by these changes in terms of conferring increased MICs of Q-D, CLI, and DAL relative to
lsa
OG
while the phenotype of mutagenized
lsa
V
(
lsa
V-M
) was less influenced, with moderately decreased MICs, primarily to CLI, relative to
lsa
V
. In conclusion, this study found that changes in different regions of the
E. faecalis lsa
locus influence the ability of cloned
lsa
to confer resistance to Q-D, CLI, and DAL.