bluuebunny/crossref_metadata_2025_split huggingface dataset:
Analysis of the role of the pyruvate decarboxylase gene family in Arabidopsis thaliana under low‐oxygen conditions
Authors: Mithran M. , Paparelli E. , Novi G. , Perata P. , Loreti E. 
Published: April 2013

AbstractPlants under low‐oxygen conditions adapt their metabolism by inducing the fermentative pathway, with ethanol as the predominant end product. Activities of pyruvate decarboxylase (PDC) and alcohol dehydrogenase (ADH) are required for this pathway. While a single gene encodes ADH in Arabidopsis, a family of four genes codes PDC. The availability of microarray data sets enabled the relative importance of the four PDC genes under low oxygen to be assessed, and revealed that, contrary to previous published evidence, not only PDC1 but also PDC2 plays a role under hypoxic conditions. We observed a high level of expression, both at transcript and protein levels of PDCs, even under aerobic conditions when ADH is almost absent. This suggests that PDC has a role under aerobic conditions, which is not coupled to fermentative metabolism. The expression of both PDC1 and PDC2 is strongly up‐regulated under low oxygen. PDC1 is predominantly present in roots, while PDC2 appears to be leaf‐specific. We showed that mutations in both PDC1 and PDC2 result in lower tolerance to submergence.
Effect of cadmium and calcium treatments on phytochelatin and glutathione levels in citrus plants
Authors: López‐Climent M. F. , Arbona V. , Pérez‐Clemente R. M. , Zandalinas S. I. , Gómez‐Cadenas A. 
Published: April 2013

AbstractIndustry residues, phosphate fertilisers and wastewater as a source of irrigation have considerably increased levels of heavy metals in the soil, mainly cadmium (Cd2+). To test the effects of a calcium (Ca2+) treatment on Cd2+ accumulation and plant tolerance to this heavy metal, plants of two citrus genotypes, Cleopatra mandarin (CM) and Carrizo citrange (CC), were watered with increasing concentrations of Cd2+, and phytochelatin (PC) and glutathione (GSH) content were measured. Both genotypes were able to synthesise PCs in response to heavy metal intoxication, although CM seems to be a better Cd2+ excluder than CC. However, data indicate that CC plants had a higher capacity for regenerating GSH than CM plants. In this context, the effects of Ca2+ treatment on Cd2+ accumulation, plant survival and PC, GSH and oxidised glutathione (GSSG) content were assessed. Data indicate that treatment with Ca2+ had two positive effects on citrus physiology: it reduced Cd+2 uptake into roots and also increased GSH content (even in the absence of Cd2+). Overall, the data indicate that although Cd2+ exclusion is a powerful mechanism to avoid heavy metal build‐up into photosynthetic organs, the capacity to maintain optimum GSH levels to feed PC biosynthesis could also be an important factor in stress tolerance.
Comparative demography of two co‐occurring Linum species with different distribution patterns
Authors: Münzbergová Z. 
Published: April 2013

AbstractUnderstanding similarities and differences in population dynamics of closely related species is a key prerequisite in attempts to apply knowledge obtained in one species to another species, e.g., for the purpose of predicting future fate of populations of various rare species. It can be expected that species will have similar population dynamics if they are closely related and share similar habitats. Contrasting population sizes and distribution patterns may, however, indicate that the population dynamics will be different. To understand similarities and differences in population dynamics of closely related species, I studied demography of two congeneric endangered species, Linum flavum and L. tenuifolium co‐occurring in dry grasslands. Linum flavum occurs with a lower number of large populations, while L. tenuifolium occurs as a large number of small populations. The results showed that L. flavum had higher population growth rates, relied more on survival and growth and its populations were more persistent. In contrast, populations of L. tenuifolium were more prone to extinction and frequent recolonisation was necessary for their survival in the landscape. This was in accordance with observed population sizes of the two species and their frequency in the landscape. The results indicate that despite being closely related and occurring in the same habitat types, the two Linum species have different growth strategies. The strong differences in population dynamics between the two species suggest that similarity in population sizes and frequency of the species in the landscape may be more important when attempting to transfer knowledge between species than is taxonomic relatedness.
Observation of polyphosphate bodies and DNA during the cell division cycle of Synechococcus elongatus PCC 7942
Authors: Seki Y. , Nitta K. , Kaneko Y. 
Published: April 2013

AbstractAlthough most cyanobacterial cells contain prominent polyphosphate bodies in the central cytoplasmic area enclosed by the peripheral thylakoid membranes, their roles are not fully understood. Storing phosphate for nucleotide production might be one of their important roles in survival of the cells. As a step towards identifying a possible contribution of the polyphosphate bodies to DNA synthesis, the relationship between polyphosphate bodies and DNA throughout cell division cycle of Synechococcus elongatus PCC 7942 cells cultured under light/dark cycles was investigated with light and electron microscopy. During the dark period, the average size of polyphosphate bodies increased gradually without significant change in their number and distribution. However, during the light period, the number of polyphosphate bodies increased, while the size of each polyphosphate body decreased and cells elongated until the end of the light period, when most cells divided. The ratio of the content of polyphosphate bodies to cell length increased gradually during the dark period and decreased during the light period. Hoechst 33342‐stained DNA appeared diffuse during the dark period, but in the light period it became condensed and eventually formed a wavy, rope‐like structure prior to cell division. Close association between fibres containing DNA and polyphosphate bodies was demonstrated by TEM using DNA‐specific staining and BrdU labelling. These regular coordinated changes of polyphosphate bodies and DNA shape during the cell division cycle, together with their intimate interaction, imply a role of polyphosphate bodies in supplying material for DNA.
Do Employees Care About Their Relative Income Position? Behavioral Evidence Focusing on Performance in Professional Team Sport
Authors: Frey Bruno S. , Schaffner Markus , Schmidt Sascha L. , Torgler Benno 
Published: April 2013

ObjectiveDo employees care about their relative (economic) position in comparison to their co‐workers in an organization? And if so, does it raise or lower their performance? While the topic is widely discussed in the literature, behavioral evidence on these important questions is relatively rare.MethodsThis article explores the pay‐performance relationship using a sports data set. The strength of analyzing such data is that sports tournaments take place in a very controlled environment that helps to isolate a relative income effect.ResultsUsing two large unique data sets that cover 26 seasons in basketball and eight seasons in soccer (Bundesliga), we find considerable support for the idea that a relative income disadvantage is correlated with a decrease in individual performance. In addition, there does not seem to be any tolerance for income disparity based on the hope that such differences may signal that better times are ahead.ConclusionsThis suggests the need to consider the impact of the relative income position when designing pay‐for‐performance mechanisms within firms and teams.
GABI‐DUPLO: a collection of double mutants to overcome genetic redundancy in Arabidopsis thaliana
Authors: Bolle Cordelia , Huep Gunnar , Kleinbölting Nils , Haberer Georg , Mayer Klaus , Leister Dario , Weisshaar Bernd 
Published: April 2013

SummaryOwing to duplication events in its progenitor, more than 90% of the genes in the Arabidopsis thaliana genome are members of multigene families. A set of 2108 gene families, each consisting of precisely two unlinked paralogous genes, was identified in the nuclear genome of A. thaliana on the basis of sequence similarity. A systematic method for the creation of double knock‐out lines for such gene pairs, designated as DUPLO lines, was established and 200 lines are now publicly available. Their initial phenotypic characterisation led to the identification of seven lines with defects that emerge only in the adult stage. A further six lines display seedling lethality and 23 lines were lethal before germination. Another 14 lines are known to show phenotypes under non‐standard conditions or at the molecular level. Knock‐out of gene pairs with very similar coding sequences or expression profiles is more likely to produce a mutant phenotype than inactivation of gene pairs with dissimilar profiles or sequences. High coding sequence similarity and highly similar expression profiles are only weakly correlated, implying that promoter and coding regions of these gene pairs display different degrees of diversification.
Site‐specific T–DNA integration in Arabidopsis thaliana mediated by the combined action of CRE recombinase and ϕC31 integrase
Authors: De Paepe Annelies , De Buck Sylvie , Nolf Jonah , Van Lerberge Els , Depicker Ann 
Published: April 2013

SummaryRandom T–DNA integration into the plant host genome can be problematic for a variety of reasons, including potentially variable transgene expression as a result of different integration positions and multiple T–DNA copies, the risk of mutating the host genome and the difficulty of stacking well‐defined traits. Therefore, recombination systems have been proposed to integrate the T–DNA at a pre‐selected site in the host genome. Here, we demonstrate the capacity of the ϕC31 integrase (INT) for efficient targeted T–DNA integration. Moreover, we show that the iterative site‐specific integration system (ISSI), which combines the activities of the CRE recombinase and INT, enables the targeting of genes to a pre‐selected site with the concomitant removal of the resident selectable marker. To begin, plants expressing both the CRE and INT recombinase and containing the target attP site were constructed. These plants were supertransformed with a T–DNA vector harboring the loxP site, the attB sites, a selectable marker and an expression cassette encoding a reporter protein. Three out of the 35 transformants obtained (9%) showed transgenerational site‐specific integration (SSI) of this T–DNA and removal of the resident selectable marker, as demonstrated by PCR, Southern blot and segregation analysis. In conclusion, our results show the applicability of the ISSI system for precise and targeted Agrobacterium‐mediated integration, allowing the serial integration of transgenic DNA sequences in plants.
Staphylococcus aureus Formyl-Methionyl Transferase Mutants Demonstrate Reduced Virulence Factor Production and Pathogenicity
Authors: Lewandowski Thomas , Huang Jianzhong , Fan Frank , Rogers Shannon , Gentry Daniel , Holland Reannon , DeMarsh Peter , Aubart Kelly , Zalacain Magdalena 
Published: April 2013

ABSTRACT

Inhibitors of peptide deformylase (PDF) represent a new class of antibacterial agents with a novel mechanism of action. Mutations that inactivate formyl methionyl transferase (FMT), the enzyme that formylates initiator methionyl-tRNA, lead to an alternative initiation of protein synthesis that does not require deformylation and are the predominant cause of resistance to PDF inhibitors in
Staphylococcus aureus
. Here, we report that loss-of-function mutations in FMT impart pleiotropic effects that include a reduced growth rate, a nonhemolytic phenotype, and a drastic reduction in production of multiple extracellular proteins, including key virulence factors, such as α-hemolysin and Panton-Valentine leukocidin (PVL), that have been associated with
S. aureus
pathogenicity. Consequently,
S. aureus
FMT mutants are greatly attenuated in neutropenic and nonneutropenic murine pyelonephritis infection models and show very high survival rates compared with wild-type
S. aureus
. These newly discovered effects on extracellular virulence factor production demonstrate that FMT-null mutants have a more severe fitness cost than previously anticipated, leading to a substantial loss of pathogenicity and a restricted ability to produce an invasive infection.
Pharmacokinetics and Pharmacodynamics of Fluconazole for Cryptococcal Meningoencephalitis: Implications for Antifungal Therapy andIn VitroSusceptibility Breakpoints
Authors: Sudan Ajay , Livermore Joanne , Howard Susan J. , Al-Nakeeb Zaid , Sharp Andrew , Goodwin Joanne , Gregson Lea , Warn Peter A. , Felton Tim W. , Perfect John R. , Harrison Thomas S. , Hope William W. 
Published: April 2013

ABSTRACTFluconazole is frequently the only antifungal agent that is available for induction therapy for cryptococcal meningitis. There is relatively little understanding of the pharmacokinetics and pharmacodynamics (PK-PD) of fluconazole in this setting. PK-PD relationships were estimated with 4 clinical isolates ofCryptococcus neoformans. MICs were determined using Clinical and Laboratory Standards Institute (CLSI) methodology. A nonimmunosuppressed murine model of cryptococcal meningitis was used. Mice received two different doses of fluconazole (125 mg/kg of body weight/day and 250 mg/kg of body weight/day) orally for 9 days; a control group of mice was not given fluconazole. Fluconazole concentrations in plasma and in the cerebrum were determined using high-performance liquid chromatography (HPLC). The cryptococcal density in the brain was estimated using quantitative cultures. A mathematical model was fitted to the PK-PD data. The experimental results were extrapolated to humans (bridging study). The PK were linear. A dose-dependent decline in fungal burden was observed, with near-maximal activity evident with dosages of 250 mg/kg/day. The MIC was important for understanding the exposure-response relationships. The mean AUC/MIC ratio associated with stasis was 389. The results of the bridging study suggested that only 66.7% of patients receiving 1,200 mg/kg would achieve or exceed an AUC/MIC ratio of 389. The potential breakpoints for fluconazole againstCryptococcus neoformansfollow: susceptible, ≤2 mg/liter; resistant, >2 mg/liter. Fluconazole may be an inferior agent for induction therapy because many patients cannot achieve the pharmacodynamic target. Clinical breakpoints are likely to be significantly lower than epidemiological cutoff values. The MIC may guide the appropriate use of fluconazole. If fluconazole is the only option for induction therapy, then the highest possible dose should be used.
Heteroresistance to Fosfomycin Is Predominant in Streptococcus pneumoniae and Depends on the
murA1
Gene
Authors: Engel Hansjürg , Gutiérrez-Fernández Javier , Flückiger Christine , Martínez-Ripoll Martín , Mühlemann Kathrin , Hermoso Juan A. , Hilty Markus , Hathaway Lucy J. 
Published: April 2013

ABSTRACT

Fosfomycin targets the first step of peptidoglycan biosynthesis in
Streptococcus pneumoniae
catalyzed by UDP-
N
-acetylglucosamine enolpyruvyltransferase (MurA1). We investigated whether heteroresistance to fosfomycin occurs in
S. pneumoniae
. We found that of 11 strains tested, all but 1 (Hungary
19A
) displayed heteroresistance and that deletion of
murA1
abolished heteroresistance. Hungary
19A
differs from the other strains by a single amino acid substitution in MurA1 (Ala
364
Thr). To test whether this substitution is responsible for the lack of heteroresistance, it was introduced into strain D39. The heteroresistance phenotype of strain D39 was not changed. Furthermore, no relevant structural differences between the MurA1 crystal structures of heteroresistant strain D39 and nonheteroresistant strain Hungary
19A
were found. Our results reveal that heteroresistance to fosfomycin is the predominant phenotype of
S. pneumoniae
and that MurA1 is required for heteroresistance to fosfomycin but is not the only factor involved. The findings provide a caveat for any future use of fosfomycin in the treatment of pneumococcal infections.
Analysis of Anti-Clostridium difficile Activity of Thuricin CD, Vancomycin, Metronidazole, Ramoplanin, and Actagardine, both Singly and in Paired Combinations
Authors: Mathur Harsh , O'Connor Paula M. , Hill Colin , Cotter Paul D. , Ross R. Paul 
Published: April 2013

ABSTRACT

Due to the ongoing problem of recurrence of
Clostridium difficile
-associated diarrhea following antibiotic treatment, there is an urgent need for alternative treatment options. We assessed the MICs of five antimicrobials singly and in combinations against a range of
C. difficile
clinical isolates. Ramoplanin-actagardine combinations were particularly effective, with partial synergistic/additive effects observed against 61.5% of
C. difficile
strains tested.
Complex Patterns of Protease Inhibitor Resistance among Antiretroviral Treatment-Experienced HIV-2 Patients from Senegal: Implications for Second-Line Therapy
Authors: Raugi Dana N. , Smith Robert A. , Ba Selly , Toure Macoumba , Traore Fatou , Sall Fatima , Pan Charlotte , Blankenship Lindsey , Montano Alexandra , Olson Julia , Dia Badiane Ndeye Mery , Mullins James I. , Kiviat Nancy B. , Hawes Stephen E. , Sow Papa Salif , Gottlieb Geoffrey S. 
Published: April 2013

ABSTRACTProtease inhibitor (PI)-based antiretroviral therapy (ART) can effectively suppress HIV-2 plasma load and increase CD4 counts; however, not all PIs are equally active against HIV-2, and few data exist to support second-line therapy decisions. To identify therapeutic options for HIV-2 patients failing ART, we evaluated the frequency of PI resistance-associated amino acid changes in HIV-2 sequences from a cohort of 43 Senegalese individuals receiving unboosted indinavir (n= 18 subjects)-, lopinavir/ritonavir (n= 4)-, or indinavir and then lopinavir/ritonavir (n= 21)-containing ART. Common protease substitutions included V10I, V47A, I54M, V71I, I82F, I84V, L90M, and L99F, and most patients harbored viruses containing multiple changes. Based on genotypic data, we constructed a panel of 15 site-directed mutants of HIV-2ROD9containing single- or multiple-treatment-associated amino acid changes in the protease-encoding region ofpol. We then quantified the susceptibilities of the mutants to the HIV-2 “active” PIs saquinavir, lopinavir, and darunavir using a single-cycle assay. Relative to wild-type HIV-2, the V47A mutant was resistant to lopinavir (6.3-fold increase in the mean 50% effective concentration [EC50]), the I54M variant was resistant to darunavir and lopinavir (6.2- and 2.7-fold increases, respectively), and the L90M mutant was resistant to saquinavir (3.6-fold increase). In addition, the triple mutant that included I54M plus I84V plus L90M was resistant to all three PIs (31-, 10-, and 3.8-fold increases in the mean EC50for darunavir, saquinavir, and lopinavir, respectively). Taken together, our data demonstrate that PI-treated HIV-2 patients frequently harbor viruses that exhibit complex patterns of PI cross-resistance. These findings suggest that sequential PI-based regimens for HIV-2 treatment may be ineffective.
Novel Bacteriophage Lysin with Broad Lytic Activity Protects against Mixed Infection by Streptococcus pyogenes and Methicillin-Resistant Staphylococcus aureus
Authors: Gilmer Daniel B. , Schmitz Jonathan E. , Euler Chad W. , Fischetti Vincent A. 
Published: April 2013

ABSTRACT

Methicillin-resistant
Staphylococcus aureus
(MRSA) and
Streptococcus pyogenes
(group A streptococcus [GrAS]) cause serious and sometimes fatal human diseases. They are among the many Gram-positive pathogens for which resistance to leading antibiotics has emerged. As a result, alternative therapies need to be developed to combat these pathogens. We have identified a novel bacteriophage lysin (PlySs2), derived from a
Streptococcus suis
phage, with broad lytic activity against MRSA, vancomycin-intermediate
S. aureus
(VISA),
Streptococcus suis
,
Listeria
,
Staphylococcus simulans
,
Staphylococcus epidermidis
,
Streptococcus equi
,
Streptococcus agalactiae
(group B streptococcus [GBS]),
S. pyogenes
,
Streptococcus sanguinis
, group G streptococci (GGS), group E streptococci (GES), and
Streptococcus pneumoniae
. PlySs2 has an N-terminal cysteine-histidine aminopeptidase (CHAP) catalytic domain and a C-terminal SH3b binding domain. It is stable at 50°C for 30 min, 37°C for >24 h, 4°C for 15 days, and −80°C for >7 months; it maintained full activity after 10 freeze-thaw cycles. PlySs2 at 128 μg/ml
in vitro
reduced MRSA and
S. pyogenes
growth by 5 logs and 3 logs within 1 h, respectively, and exhibited a MIC of 16 μg/ml for MRSA. A single, 2-mg dose of PlySs2 protected 92% (22/24) of the mice in a bacteremia model of mixed MRSA and
S. pyogenes
infection. Serially increasing exposure of MRSA and
S. pyogenes
to PlySs2 or mupirocin resulted in no observed resistance to PlySs2 and resistance to mupirocin. To date, no other lysin has shown such notable broad lytic activity, stability, and efficacy against multiple, leading, human bacterial pathogens; as such, PlySs2 has all the characteristics to be an effective therapeutic.
Impact of Meropenem in Combination with Tobramycin in a Murine Model of Pseudomonas aeruginosa Pneumonia
Authors: Louie Arnold , Liu Weiguo , Fikes Steven , Brown David , Drusano G. L. 
Published: April 2013

ABSTRACT

Pseudomonas aeruginosa
pneumonia remains a difficult therapeutic problem. Optimal doses and modes of administration of single agents often do not result in acceptable outcomes. Further, emergence of resistance occurs frequently in this setting with single-agent chemotherapy. The purpose of these experiments was to evaluate combination chemotherapy with meropenem plus tobramycin for
P. aeruginosa
in a murine pneumonia model. Neutropenia was induced by cyclophosphamide. Pharmacokinetics of meropenem and tobramycin were determined using a population pharmacokinetic approach. Both drugs were given at 4-h intervals. Meropenem was administered as total daily doses of 30 to 600 mg/kg of body weight, while tobramycin doses ranged from 50 to 400 mg/kg. Combination therapy evaluated all combinations of 50, 100, and 150 mg/kg/day of tobramycin doses with 60 or 300 mg/kg/day of meropenem. Total and drug-resistant organisms were enumerated. Meropenem alone had a near-maximal effect at 60 mg/kg/day (3.18 log
10
[CFU/g] kill from stasis). The time > MIC in epithelial lining fluid (ELF) at this dose was 35.25% of 24 h. For tobramycin alone, the near-maximal effect was at 150 mg/kg/day and the area under the concentration-time curve over 24 h in the steady state divided by the MIC (AUC/MIC ratio) in ELF was 240.3. Resistance suppression occurred at an ELF AUC/MIC ratio of 110.6. For combination therapy, the near-maximal effect was reached at 60 mg/kg/day and 50 mg/kg/day of meropenem and tobramycin, which produced a 35.25% time > MIC in ELF and an ELF AUC/MIC ratio of 80.1. The interaction was additive. All combination regimens suppressed resistance. Combination therapy produced additive drug interaction and suppressed all resistance amplification. It is likely that optimal therapy for
Pseudomonas aeruginosa
pneumonia will involve a combination of agents.