bluuebunny/crossref_metadata_2025_split huggingface dataset:
Long‐term studies of freshwater macroinvertebrates: a review of the frequency, duration and ecological significance
Authors: JACKSON JOHN K. , FÜREDER LEOPOLD 
Published: January 2006

Summary1. The importance of a long‐term ecological perspective is well documented, yet the availability of long‐term data remains limited. This paper highlights the value of long‐term ecological studies of freshwater macroinvertebrates by reviewing both the availability of long‐term data and recent ecological contributions based on them.2. A survey of recent literature on stream macroinvertebrates identified 46 papers published between 1987 and 2004 that included long‐term (i.e. ≥5 years) data. Most recently published long‐term studies of stream macroinvertebrates began collecting data in the 1970s and 1980s and their duration (time between first and last year sampled) was relatively brief (median = 9 years, maximum = 96 years). Most studies did not expand their temporal perspective by incorporating older data collected by other researchers.3. Recent long‐term studies of macroinvertebrates have made major contributions to our understanding of interannual variation and cycles, complex abiotic and biotic interactions, and natural and anthropogenic disturbance and recovery. Without these studies, we would know much less about the magnitude of natural temporal variation, the importance of physical and biological disturbance and interactions, the role of pathogens and introduced species, the overall impact of pollution and the effectiveness of protection and remediation efforts.4. If we are to encourage long‐term perspectives in our science, we need to facilitate the transfer of individual studies, as well as knowledge and data, among scientists. This includes efforts to archive and annotate data more effectively, so that they can be more easily incorporated into future research.
Repeatability of extra‐pair mating in tree swallows
Authors: WHITTINGHAM LINDA A. , DUNN PETER O. , STAPLETON MARY K. 
Published: January 2006

AbstractModels of sexual selection assume that female mating preferences are heritable and, thus, repeatable for individual females across multiple mating episodes. Previous studies of the repeatability of female preference have examined individuals in captivity and focused presumably on social mate choice. However, extra‐pair mating is widespread and can also influence sexual selection. We examined the repeatability of extra‐pair mating in a wild population of tree swallows (Tachycineta bicolor) by experimentally inducing females to lay two clutches in rapid succession within the same season. We found that the proportion of extra‐pair young and the number of extra‐pair sires were highly repeatable for individual females. However, the repeatability of specific extra‐pair sires was low. We suggest that this unusual pattern of mating may be due to females maximizing the heterozygosity of their offspring.
NrrA, a nitrogen‐responsive response regulator facilitates heterocyst development in the cyanobacterium Anabaena sp. strain PCC 7120
Authors: Ehira Shigeki , Ohmori Masayuki 
Published: January 2006

SummaryThe heterocyst is a specialized cell for nitrogen fixation in the filamentous cyanobacteria, and its development is triggered by limitation of combined nitrogen in the medium. During heterocyst development, patterns of gene expression change dramatically. We identified seven genes encoding transcriptional regulators that were upregulated by nitrogen deprivation in Anabaena PCC 7120, using an Anabaena oligonucleotide microarray. Among them, the nrrA gene, which encodes a response regulator of the OmpR family with a DNA‐binding domain, has shown the most prominent induction after nitrogen deprivation. Expression of nrrA increased all through the filaments within 3 h of nitrogen deprivation and became higher in proheterocysts than in vegetative cells after 12 h. Sequence analysis of the promoter region of nrrA indicated that the induction of nrrA depended on NtcA, which is the global nitrogen regulator in cyanobacteria. In the nrrA deletion mutant, heterocyst development was delayed and the induction of hetR, which is the master gene in regulation of heterocyst development, was diminished up to 24 h nitrogen deprivation. It is concluded that nrrA facilitates heterocyst development.
White lupin has developed a complex strategy to limit microbial degradation of secreted citrate required for phosphate acquisition
Authors: WEISSKOPF LAURE , ABOU‐MANSOUR ELIANE , FROMIN NATHALIE , TOMASI NICOLA , SANTELIA DIANA , EDELKOTT IRIS , NEUMANN GÜNTER , ARAGNO MICHEL , TABACCHI RAFFAELE , MARTINOIA ENRICO 
Published: January 2006

ABSTRACTWhite lupins (Lupinus albus L.) respond to phosphate deficiency by producing special root structures called cluster roots. These cluster roots secrete large amounts of carboxylates into the rhizosphere, mostly citrate and malate, which act as phosphate solubilizers and enable the plant to grow in soils with sparingly available phosphate. The success and efficiency of such a P‐acquisition strategy strongly depends on the persistence and stability of the carboxylates in the soil, a parameter that is influenced to a large extent by biodegradation through rhizosphere bacteria and fungi. In this study, we show that white lupin roots use several mechanisms to reduce microbial growth. The abundance of bacteria associated with cluster roots was decreased at the mature state of the cluster roots, where a burst of organic acid excretion and a drastic pH decrease is observed. Excretion of phenolic compounds, mainly isoflavonoids, induced fungal sporulation, indicating that vegetative growth, and thus potential citrate consumption, is reduced. In addition, the activity of two antifungal cell wall‐degrading enzymes, chitinase and glucanase, were highest at the stage preceding the citrate excretion. Therefore, our results suggest that white lupin has developed a complex strategy to reduce microbial degradation of the phosphate‐solubilizing agents.
Temporal autocorrelation and stochastic population growth
Authors: Tuljapurkar Shripad , Haridas C. V. 
Published: January 2006

AbstractHow much does environmental autocorrelation matter to the growth of structured populations in real life contexts? Interannual variances in vital rates certainly do, but it has been suggested that between‐year correlations may not. We present an analytical approximation to stochastic growth rate for multistate Markovian environments and show that it is accurate by testing it in two empirically based examples. We find that temporal autocorrelation has sizeable effect on growth rates of structured populations, larger in many cases than the effect of interannual variability. Our approximation defines a sensitivity to autocorrelated variability, showing how demographic damping and environmental pattern interact to determine a population's stochastic growth rate.
Direct mass spectrometric peptide profiling and fragmentation of larval peptide hormone release sites in Drosophila melanogaster reveals tagma‐specific peptide expression and differential processing
Authors: Wegener Christian , Reinl Tobias , Jänsch Lothar , Predel Reinhard 
Published: January 2006

AbstractRegulatory peptides represent a diverse group of messenger molecules. In insects, they are produced by endocrine cells as well as secretory neurones within the CNS. Many regulatory peptides are released as hormones into the haemolymph to regulate, for example, diuresis, heartbeat or ecdysis behaviour. Hormonal release of neuropeptides takes place at specialized organs, so‐called neurohaemal organs. We have performed a mass spectrometric characterization of the peptide complement of the main neurohaemal organs and endocrine cells of the Drosophila melanogaster larva to gain insight into the hormonal communication possibilities of the fruit fly. Using matrix‐assisted laser desorption ionization time‐of‐flight (MALDI‐TOF) and MALDI‐TOF‐TOF tandem mass spectrometry, we detected 23 different peptides of which five were unpredicted by previous genome screenings. We also found a hitherto unknown peptide product of the capa gene in the ring gland and transverse nerves, suggesting that it might be released as hormone. Our results show that the peptidome of the neurohaemal organs is tagma‐specific and does not change during metamorphosis. We also provide evidence for the first case of differential prohormone processing in Drosophila.
Endogenous GD3 ganglioside induces apoptosis in U‐1242 MG glioma cells
Authors: Saqr H. E. , Omran O. , Dasgupta S. , Yu R. K. , Oblinger J. L. , Yates A. J. 
Published: January 2006

AbstractGD3 ganglioside induces apoptosis in several cell types, but the molecular events through which this occurs are largely unknown. We investigated the apoptotic effects of GD3 expression using U‐1242 MG glioblastoma cells, as these cells synthesize almost exclusively GM3 and GM2 but not GD3. To express GD3 under the control of the TetOn system with minimum leakage, we modified the system by constructing a single tri‐cistronic retrovirus vector containing three genes separated by two internal ribosome entry sites: (a) transcriptional silencer, tTS; (b) mutant of reverse transcriptional activator, rtTA2(S)‐M2 (provided by H. Bujard, Heidelberg, Germany); and (c) enhanced green fluorescent protein (EGFP), as an indicator of the tri‐cistronic gene expression. Using flow cytometry, we selected glioma cells (U1242MG‐GD3 clone) that express high levels of GD3 in response to doxycycline. Expression of GD3 was associated with apoptosis as verified by annexin‐V binding, TdT‐mediated dUTPnick end‐labelling assay (TUNEL), and EGFP degradation. GD3‐induced apoptosis occurred via caspase‐8 activation, as GD3 caused cleavage of caspase‐8 and inhibition of caspase‐8 activation by zlETD‐fmk minimized GD3‐induced apoptosis.
Mapping superoxide dismutase 1 domains of non‐native interaction: roles of intra‐ and intermolecular disulfide bonding in aggregation
Authors: Wang Jiou , Xu Guilian , Borchelt David R. 
Published: January 2006

AbstractSuperoxide dismutase 1 (SOD1) proteins harboring mutations linked to familial amyotrophic lateral sclerosis (FALS) uniformly show heightened potential to form high molecular weight structures. Here, we examine the domains of SOD1 that are involved in forming these structures (aggregates) and study the role of intra‐ and intermolecular disulfide bonds. An analysis of disease mutations identified to date reveals a non‐random distribution with predominant occurrence at residues within highly conserved β‐strands or at highly conserved residues in loop domains. Using a cell transfection assay for aggregation, we determined that no single domain in SOD1 is indispensable in the formation of sedimentable aggregates, suggesting multiple potential motifs in the protein mediate non‐native interactions. By a cell‐free aggregation assay, analysis of transgenic mouse tissues, and mutagenesis approaches, we found evidence that redox conditions may modulate SOD1 aggregation; reduction of the native intramolecular disulfide bonds may predispose SOD1 to unfolding and aggregation, whereas non‐native intermolecular disulfide linkages may help stabilize aggregates in vivo. The results suggest a possible mechanism for diversity in the structures formed by different SOD1 mutants, and define a potential contribution of redox conditions to SOD1 aggregation.
Who Searches the Internet for Health Information?
Authors: Bundorf M. Kate , Wagner Todd H. , Singer Sara J. , Baker Laurence C. 
Published: January 2006

Objective. To determine what types of consumers use the Internet as a source of health information.Data Sources. A survey of consumer use of the Internet for health information conducted during December 2001 and January 2002.Study Design. We estimated multivariate regression models to test hypotheses regarding the characteristics of consumers that affect information seeking behavior.Data Collection. Respondents were randomly sampled from an Internet‐enabled panel of over 60,000 households. Our survey was sent to 12,878 panel members, and 69.4 percent of surveyed panel members responded. We collected information about respondents' use of the Internet to search for health information and to communicate about health care with others using the Internet or e‐mail within the last year.Principal Findings. Individuals with reported chronic conditions were more likely than those without to search for health information on the Internet. The uninsured, particularly those with a reported chronic condition, were more likely than the privately insured to search. Individuals with longer travel times for their usual source of care were more likely to use the Internet for health‐related communication than those with shorter travel times.Conclusions. Populations with serious health needs and those facing significant barriers in accessing health care in traditional settings turn to the Internet for health information.
ARE COMMON STOCKS A HEDGE AGAINST INFLATION?
Authors: Luintel Kul B. , Paudyal Krishna 
Published: January 2006

AbstractWe test whether U.K. common stocks hedge against inflation using a framework of the tax‐augmented Fisher hypothesis. Aggregate and disaggregate (seven industry groups) monthly data covering 48 years are used. All pairs of stock and retail price indexes are cointegrated. Tests in most cases reveal significant shifts in the cointegrating vectors, and accounting for these shifts improves the precision of the estimates. The point estimates of goods price elasticity are significantly above unity in all but two cases. These findings, though in sharp contrast to most existing findings that report price elasticity of below unity, appear theoretically more plausible because nominal stock returns must exceed the inflation rate to insulate tax‐paying investors.
ESTIMATING EXPECTED EXCESS RETURNS USING HISTORICAL AND OPTION‐IMPLIED VOLATILITY
Authors: Corrado Charles J. , Miller Thomas W. 
Published: January 2006

AbstractWe test the relation between expected and realized excess returns for the S&P 500 index from January 1994 through December 2003 using the proportional reward‐to‐risk measure to estimate expected returns. When risk is measured by historical volatility, we find no relation between expected and realized excess returns. In contrast, when risk is measured by option‐implied volatility, we find a positive and significant relation between expected and realized excess returns in the 1994–1998 subperiod. In the 1999–2003 subperiod, the option‐implied volatility risk measure yields a positive, but statistically insignificant, risk‐return relation. We attribute this performance difference to the fact that, in the 1994–1998 subperiod, return volatility was lower and the average return was much higher than in the 1999–2003 subperiod, thereby increasing the signal‐to‐noise ratio in the latter subperiod.
Effect of BCG vaccine on peritoneal endometriotic implants in a rat model of endometriosis
Authors: ITIL Ismail Mete , CIRPAN Teksin , AKERCAN Fuat , GAMAA Akram , KAZANDI Mert , KAZANDI Ali Can , YILDIZ Pinar Solmaz , ASKAR Niyazi 
Published: January 2006

AbstractObjective:  To investigate the effect of Bacillus Calmette–Guerin (BCG) vaccine on peritoneal implantation of endometrial tissue in rats.Methods:  Forty sexually mature virgin Wistar albino rats weighing 190–200 g were randomly assigned (double blind) to two groups. The rats in the first group were vaccinated with 0.1 mL BCG and those in the second group were injected with 0.1 mL saline into the tail, intracutaneously. All the rats underwent median laparotomy after 4 weeks of vaccination or injection. The right uterine horn was excised, and the two samples of endometrial tissue dissected from myometrium were implanted on each side of peritoneum at the 2 cm lateral line of the median laparotomy incision. The implanted peritoneal segments were excised after 8 weeks of laparotomy. The tissue samples were accepted, histologically, as endometriosis when both glands and stroma of endometrial tissue were seen in sections.Results:  Thirty‐six implants from the study group and 34 implants from the control group were obtained. Ten and 23 implants were accepted as endometriosis in the study and control group, respectively. The number of endometriotic foci were significantly lower in the study group than in the control group (P = 0.01).Conclusions:  Stimulation of the cellular immune response with BCG vaccine could exert an inhibitory effect on ectopic endometriotic implants.
Mutations Conferring Aminoglycoside and Spectinomycin Resistance in
Borrelia burgdorferi
Authors: Criswell Daniel , Tobiason Virginia L. , Lodmell J. Stephen , Samuels D. Scott 
Published: January 2006

ABSTRACT

We have isolated and characterized in vitro mutants of the Lyme disease agent
Borrelia burgdorferi
that are resistant to spectinomycin, kanamycin, gentamicin, or streptomycin, antibiotics that target the small subunit of the ribosome. 16S rRNA mutations A1185G and C1186U, homologous to
Escherichia coli
nucleotides A1191 and C1192, conferred >2,200-fold and 1,300-fold resistance to spectinomycin, respectively. A 16S rRNA A1402G mutation, homologous to
E. coli
A1408, conferred >90-fold resistance to kanamycin and >240-fold resistance to gentamicin. Two mutations were identified in the gene for ribosomal protein S12, at a site homologous to
E. coli
residue Lys-87, in mutants selected in streptomycin. Substitutions at codon 88, K88R and K88E, conferred 7-fold resistance and 10-fold resistance, respectively, to streptomycin on
B. burgdorferi
. The 16S rRNA A1185G and C1186U mutations, associated with spectinomycin resistance, appeared in a population of
B. burgdorferi
parental strain B31 at a high frequency of 6 × 10
−6
. These spectinomycin-resistant mutants successfully competed with the wild-type strain during 100 generations of coculture in vitro. The aminoglycoside-resistant mutants appeared at a frequency of 3 × 10
−9
to 1 ×10
−7
in a population and were unable to compete with wild-type strain B31 after 100 generations. This is the first description of mutations in the
B. burgdorferi
ribosome that confer resistance to antibiotics. These results have implications for the evolution of antibiotic resistance, because the 16S rRNA mutations conferring spectinomycin resistance have no significant fitness cost in vitro, and for the development of new selectable markers.
Novel Compounds Active against
Leishmania major
Authors: St. George Stephanie , Bishop Jeanette V. , Titus Richard G. , Selitrennikoff Claude P. 
Published: January 2006

ABSTRACT

Leishmania major
is an important trypanosomatid pathogen that causes leishmaniasis, which is a serious disease in much of the Old World. Current treatments include a small number of antimony compounds that, while somewhat effective, are limited by serious side effects. We have screened a small portion of a unique chemical library and have found at least three novel compounds that are effective against
L. tarentolae
and
L. major
in vitro and in a murine macrophage model of
L. major
infection. These compounds were effective in both assays at doses significantly lower than those of sodium stibogluconate (Pentostam) and represent possible candidates for drug development.
Malaria Parasites Can Develop Stable Resistance to Artemisinin but Lack Mutations in Candidate Genes
atp6
(Encoding the Sarcoplasmic and Endoplasmic Reticulum Ca
2+
ATPase),
tctp
,
mdr1
, and
cg10
Authors: Afonso A. , Hunt P. , Cheesman S. , Alves A. C. , Cunha C. V. , do Rosário V. , Cravo P. 
Published: January 2006

ABSTRACT

Resistance of
Plasmodium falciparum
to drugs such as chloroquine and sulfadoxine-pyrimethamine is a major problem in malaria control. Artemisinin (ART) derivatives, particularly in combination with other drugs, are thus increasingly used to treat malaria, reducing the probability that parasites resistant to the components will emerge. Although stable resistance to artemisinin has yet to be reported from laboratory or field studies, its emergence would be disastrous because of the lack of alternative treatments. Here, we report for the first time, to our knowledge, genetically stable and transmissible ART and artesunate (ATN)-resistant malaria parasites. Each of two lines of the rodent malaria parasite
Plosmodium chabaudi chabaudi
, grown in the presence of increasing concentrations of ART or ATN, showed 15-fold and 6-fold increased resistance to ART and ATN, respectively. Resistance remained stable after cloning, freeze-thawing, after passage in the absence of drug, and transmission through mosquitoes. The nucleotide sequences of the possible genetic modulators of ART resistance (
mdr1
,
cg10
,
tctp
, and
atp6
) of sensitive and resistant parasites were compared. No mutations in these genes were identified. In addition we investigated whether changes in the copy number of these genes could account for resistance but found that resistant parasites retained the same number of copies as their sensitive progenitors. We believe that this is the first report of a malaria parasite with genetically stable and transmissible resistance to artemisinin or its derivatives.
Diagnostic PCR Analysis of the Occurrence of Methicillin and Tetracycline Resistance Genes among
Staphylococcus aureus
Isolates from Phase 3 Clinical Trials of Tigecycline for Complicated Skin and Skin Structure Infections
Authors: Jones C. Hal , Tuckman Margareta , Howe Anita Y. M. , Orlowski Mark , Mullen Stanley , Chan Karen , Bradford Patricia A. 
Published: January 2006

ABSTRACT

Diagnostic PCR assays were developed to track common genetic determinants of oxacillin resistance as well as resistance to classical tetracyclines in
Staphylococcus aureus
isolates from the recently completed worldwide phase 3 clinical trials of tigecycline. A total of 503 unique
S. aureus
strains isolated from complicated skin and skin structure infections were analyzed. The
mecA
gene was amplified from 120 strains (23.9%) determined to be resistant to oxacillin (MICs ≥ 4 μg/ml). The prevalence of the
mecA
gene was found to vary regionally from 6.5% to 50.9% among isolates originating in Eastern Europe and North America, respectively. The presence of a tetracycline resistance determinant,
tet
(M) or
tet
(K), among methicillin-resistant
S. aureus
(MRSA) isolates also varied regionally, with a range of 11.9% to 46.2% among isolates tested from North America and Eastern Europe, respectively. The occurrence of a tetracycline resistance marker in methicillin-susceptible
S. aureus
(MSSA) strains varied from 2.5 to 16.1% among the isolates tested across the regions of study. The presence of
tet
(M) or
tet
(K) had no discernible effect on the tigecycline MICs for either MRSA or MSSA strains, which is consistent with the ability of the glycylcyclines to retain activity in the presence of both the ribosomal protection and efflux mechanisms of resistance to the tetracyclines.