bluuebunny/crossref_metadata_2025_split huggingface dataset:
Daily patterns of mixing and nutrient concentrations during early autumn circulation in a small sheltered lake
Authors: ALVAREZ‐COBELAS MIGUEL , VELASCO JOSÉ LUIS , VALLADOLID MARÍA , BALTANÁS ANGEL , ROJO CARMEN 
Published: April 2005

Summary1. Autumn circulation in lakes is currently conceived to occur very rapidly, being controlled mainly by wind‐power dynamics, decreasing irradiance and heat flux. In addition, autumn mixing is usually related to nutrient redistribution in the vertical column, resulting in its overall increase. To test these assumptions, mixing and nutrient dynamics in a Spanish small, wind‐sheltered, mesotrophic, seepage lake were studied daily during autumn circulation.2. The seasonal erosion of the pycnocline in Las Madres Lake was the outcome of vertical and horizontal exchanges of heat and matter. The overall mixing of the water column lasted 3 months, which was an unexpected period for a rather shallow lake. Two periods of mixing could be envisaged until full circulation was attained. First, a slightly faster period of pycnocline deepening than that predicted by the heat flux and wind stress model of Fisher et al. (1979) occurred for 41 days, mixing most of the water column down to within two meters of the bottom. Then a much slower process took place promoting frequent instability of the bottom layer and resulting in entire mixing in a further 52 days.3. Vertically, the whole mixing process was a response to weak surface cooling, resulting from the mild air temperatures of the semiarid climate of the area, and weak wind stress, because of low wind fetch and high shelter. Horizontally, a gravity current transporting cold, denser water from western shallower areas of the lake and materials produced by the decomposition of organic matter of littoral origin may produce a bottom layer of increased density, thus impinging on vertical stability. Seepage inputs of water of roughly constant temperature might also have increased bottom density. Bottom density enhancement resulted in a double diffusion process.4. Only in‐lake nitrogen content increased until full circulation was attained, whereas carbon showed no trend and phosphorus declined. External processes, such as seepage exchange and atmospheric deposition, coupled to internal processes, such as nitrification, oxidised phosphorus precipitation and complexation with organic carbon, might have been responsible for the areal nutrient patterns observed.5. Our study demonstrates that current models of water column mixing and nutrient redistribution in lakes during autumn circulation must be improved to encompass the effects of external inputs, including horizontal heat and matter exchange.
Flood effects on invertebrates, sediments and particulate organic matter in the hyporheic zone of a gravel‐bed stream
Authors: OLSEN DEAN A. , TOWNSEND COLIN R. 
Published: April 2005

Summary1. We investigated the effects of a flood on the fauna and physical habitat of the hyporheic zone of the Kye Burn, a fourth order gravel‐bed stream in New Zealand.2. Freeze core hyporheic samples (to 50 cm depth) and benthic samples (to 10 cm) were taken, along with measurements of vertical hydrological gradient, before, 2 days after and 1 month after the flood (estimated return period: 1.5 years, estimated Qmax = 10.4 m3 s−1).3. The composition of the hyporheos differed over the three sampling occasions with fewer taxa collected immediately postflood than preflood. The equitability of the community was higher on both postflood occasions, consistent with the reduced densities of two abundant taxa (Leptophlebiidae and Copepoda).4. Total invertebrate abundance was lower on the postflood occasions than preflood in both benthic (0–10 cm) and hyporheic (10–50 cm) sediments. Several taxa, including asellotan isopods and amphipods, recovered within 1 month of the event. Hyporheic densities of larval Hydora and nematodes did not differ among the three sampling occasions, but the water mite Pseudotryssaturus was more abundant 1 month after the flood than preflood. There was no evidence of vertical movements (to 50 cm) by any taxa in response to the flood.5. The proportion of fine sediments (<1 mm) in the subsurface sediments (10–50 cm) increased over the three sampling occasions and median particle size declined, but sediment porosity did not change. More particulate organic matter was found in the sediments after the flood.6. Our study provides little evidence that the hyporheic zone (to 50 cm) acted as a significant refuge during the flood event, although movements to or recolonisation from sediments deeper than 50 cm could explain the recovery of many crustacean and mite taxa within 1 month.
Impact of migratory snow geese on nitrogen and phosphorus dynamics in a freshwater reservoir
Authors: OLSON MARK H. , HAGE MELISSA M. , BINKLEY MARK D. , BINDER JAMES R. 
Published: April 2005

Summary1. We examined impacts of nutrient loading, particularly of nitrogen and phosphorus, from greater snow geese (Chen caerulescens atlantica) on a reservoir in south‐eastern Pennsylvania, U.S.A. Approximately 100 000 geese use the reservoir for 2–6 weeks prior to their spring migration northward.2. We estimated the magnitude of nutrient loading by geese during their presence and compared that to surface input and output rates. We also conducted nutrient limitation bioassay experiments to examine patterns of algal nutrient limitation upstream and downstream of the reservoir.3. During their presence from 1 February to 27 March 2001, snow geese contributed 85–93% of the phosphorus and 33–44% of the nitrogen loaded to the reservoir. Both nutrients were exported from the reservoir slowly rather than as a quick pulse. Consequently, phosphorus concentrations in the outflow were higher than in the inflow from February to the end of July. However, nitrogen concentrations were consistently lower in the outflow than the inflow.4. Nutrient limitation bioassays conducted in June and July indicated that primary production in the outflow was limited by nitrogen whereas the inflow was co‐limited by nitrogen and phosphorus. Further downstream from the reservoir, primary production was consistently phosphorus limited. Therefore, nitrogen limitation persisted long after the geese had left, but was relatively localised.
Flagellate nutritional versatility as a key to survival in two contrasting Antarctic saline lakes
Authors: LAYBOURN‐PARRY JOHANNA , MARSHALL WILLIAM A. , MARCHANT HARVEY J. 
Published: April 2005

Summary1. Seasonal patterns of grazing and photosynthesis were investigated in two saline Antarctic lakes (Highway and Ace) in the Vestfold Hills (68°S). The phototrophic nanoflagellate (PNAN) community was dominated by Pyramimonas gelidicola and two morphological forms of a cryptophyte species that occurred throughout the year. Both species were mixotrophic on bacteria, and in Highway Lake they also exploited dissolved organic carbon as determined by the uptake of fluorescently labelled dextrans.2. Clearance rates ranged between 0.02 and 0.21 nL h−1 cell−1 in Ace Lake and 0.004–1.05 nL h−1 cell−1 in Highway Lake. On occasion cryptophyte grazing equalled that of the heterotrophic nanoflagellates (HNAN).3. Photosynthetic rates showed similar trends in both lakes, but there were differences in chlorophyll a specific rates and photosynthetic efficiency, probably related to the meromictic characteristic of Ace Lake. Primary production was measurable in winter and peaked in summer following the maxima of mixotroph grazing.4. The HNAN community of Highway Lake achieved clearance rates of 0.02–1.80 nL h−1 cell−1 and removing between 50 and 693 ng bacterial carbon L−1 day−1, with highest impact in winter when HNAN were most abundant. The HNAN also ingested fluorescently labelled dextrans showing a preference for 4 and 500 kDa molecules. The more diverse HNAN community of Ace Lake had lower clearance rates (0.04–0.37 nL h−1 cell−1) and exerted a lower grazing pressure on bacterioplankton. In Highway Lake, where the HNAN community was dominated by the choanoflagellate Diaphanoeca grandis, there was a significant correlation between mean cell volume and clearance rate.5. The major feature was that the microbial plankton functioned throughout the year by employing nutritional versatility.
Alloplasmic effects on mitochondrial transcriptional activity and RNA turnover result in accumulated transcripts of Arabidopsis orfs in cytoplasmic male‐sterile Brassica napus
Authors: Leino Matti , Landgren Maria , Glimelius Kristina 
Published: April 2005

SummaryMitochondrial transcription was investigated in a cytoplasmic male‐sterile (CMS) Brassica napus line with rearranged mitochondrial (mt) DNA mostly inherited from Arabidopsis thaliana. The transcript patterns were compared with the corresponding male‐fertile progenitors, B. napus and A. thaliana, and a fertility‐restored line. Transcriptional activities, gene stoichiometry and transcript steady‐state levels were analysed for all protein and rRNA coding genes and for several orfs present in the A. thaliana mitochondrial genome. The transcriptional activities were highly variable when comparing the parental species, while the CMS and restored lines displayed similar activities. For several ribosomal protein genes transcriptional activity was reduced while it was increased for orf139 in comparison with the parental species. The differences in transcriptional activity observed could be related to differences in relative promoter strength, as gene stoichiometry between lines was very limited. Transcript steady‐state levels were more homogenous than the transcriptional activities demonstrating RNA turnover as a compensating mechanism. In the CMS line higher transcript abundance and novel transcript patterns in comparison with the parental lines were found for several genes. Of those, the transcripts for orf139, orf240a and orf294 were less abundant in the fertility‐restored line. These putative CMS‐associated transcripts were mapped by cRT‐PCR. In conclusion we show that (mt) DNA from A. thaliana was non‐correctly transcribed and processed/degraded in the B. napus nuclear background. Furthermore, the introgressed nuclear A. thaliana DNA in the fertility‐restored line contributes to a more rapid degradation of transcripts accumulated from A. thaliana derived orfs in the CMS line.
Point mutations in Arabidopsis Cullin1 reveal its essential role in jasmonate response
Authors: Ren Chunmei , Pan Jianwei , Peng Wen , Genschik Pascal , Hobbie Lawrence , Hellmann Hanjo , Estelle Mark , Gao Bida , Peng Jinrong , Sun Chuanqing , Xie Daoxin 
Published: April 2005

SummaryThe SKP1‐Cullin/Cdc53‐F‐box protein ubiquitin ligases (SCF) target many important regulatory proteins for degradation and play vital roles in diverse cellular processes. In Arabidopsis there are 11 Cullin members (AtCUL). AtCUL1 was demonstrated to assemble into SCF complexes containing COI1, an F‐box protein required for response to jasmonates (JA) that regulate plant fertility and defense responses. It is not clear whether other Cullins also associate with COI1 to form SCF complexes, thus, it is unknown whether AtCUL1, or another Cullin that assembles into SCFCOI1 (even perhaps two or more functionally redundant Cullins), plays a major role in JA signaling. We present genetic and physiological data to directly demonstrate that AtCUL1 is necessary for normal JA responses. The homozygous AtCUL1 mutants axr6‐1 and axr6‐2, the heterozygous mutants axr6/AXR6, and transgenic plants expressing mutant AtCUL1 proteins containing a single amino acid substitution from phenylalanine‐111 to valine, all exhibit reduced responses to JA. We also demonstrate that ax6 enhances the effect of coi1 on JA responses, implying a genetic interaction between COI1 and AtCUL1 in JA signaling. Furthermore, we show that the point mutations in AtCUL1 affect the assembly of COI1 into SCF, thus attenuating SCFCOI1 formation.
Functional importance of the family 1 glucosyltransferase UGT72B1 in the metabolism of xenobiotics in Arabidopsis thaliana
Authors: Brazier‐Hicks Melissa , Edwards Robert 
Published: April 2005

SummaryThe Arabidopsis type 1 UDP‐glucose‐dependent glucosyltransferase UGT72B1 is highly active in conjugating the persistent pollutants 3,4‐dichloroaniline (DCA) and 2,4,5‐trichlorophenol (TCP). To determine its importance in detoxifying xenobiotics in planta, mutant plants where the respective gene has been disrupted by T‐DNA insertion have been characterized. Extracts from the knockout ugt72B1 plants showed radically reduced conjugating activity towards DCA and TCP and the absence of immunodetectable UGT72B1 protein. In contrast, activities towards phenolic natural products were unaffected. When aseptic root cultures were fed [14C]‐DCA, compared with wild types, the ugt72B1 plants showed a reduced rate of uptake of the xenobiotic and very little metabolism to soluble DCA‐glucose or associated polar conjugates. Instead, the knockouts accumulated non‐extractable radioactive residues, most probably associated with lignification. When the feeding studies were carried out with [14C]‐TCP, rates and routes of metabolism were identical in the wild type and knockouts, with TCP‐glucoside a major product in both cases. Similar differential effects on the metabolism of DCA and TCP were obtained in whole plant studies with wild type and ugt72B1 mutants, demonstrating that while UGT72B1 had a central role in metabolizing chloroanilines in Arabidopsis, additional UGTs could compensate for the conjugation of TCP in the knockout. TCP was equally toxic to wild type and ugt72B1 plants, while surprisingly, the knockouts were less sensitive to DCA. From this it was concluded that the glucosylation of DCA may not be as effective in xenobiotic detoxification as bound‐residue formation.
Epidemiological patterns of meningococcal meningitis in Niger in 2003 and 2004: under the threat of N. meningitidis serogroup W135
Authors: Boisier Pascal , Djibo Saacou , Sidikou Fati , Mindadou Habsatou , Kairo Kiari Kaka , Djibo Ali , Goumbi Kadade , Chanteau Suzanne 
Published: April 2005

SummarySince the Neisseria meningitidis serogroup W135 epidemic in Burkina Faso in 2002, the neighbouring countries dread undergoing outbreaks. Niger has strongly enhanced the microbiological surveillance, especially by adding the polymerase chain reaction (PCR) assay to the national framework of the surveillance system. During the 2003 epidemic season, 8113 clinically suspected cases of meningitis were notified and nine districts of the 42 crossed the epidemic threshold, while during the 2004 season, the number of cases was 3521 and four districts notified epidemics. In 2003 and 2004, serogroup A was identified in most N. meningitidis from cerebrospinal fluid (CSF) specimens (89.7% of 759 and 87.2% of 406, respectively). Although serogroup W135 represented only 8.3% of the meningococcal meningitis in 2003 and 7.9% in 2004, and was not involved in outbreaks, it was widespread in various areas of the country. In the regions that notified epidemics, the proportion of serogroup W135 was tiny while it exceeded 40% in several non‐epidemic regions. Despite the wide distribution of W135 serogroup in Niger and the fears expressed in 2001, the threat of a large epidemic caused by N. meningitidis W135 seems to have been averted in Niger so far. There is no clear indication whether this serogroup will play a lasting role in the epidemiology of meningococcal meningitis or not. As early as in the 1990s, a significant but transient increase in the incidence of N. meningitidis serogroup X was observed. Close microbiological surveillance is crucial for monitoring the threat and for identifying at the earliest the serogroups involved in epidemics.
Review Article: Cerebrospinal fluid in human African trypanosomiasis: a key to diagnosis, therapeutic decision and post‐treatment follow‐up
Authors: Lejon V. , Büscher P. 
Published: April 2005

SummaryHuman African trypanosomiasis is a lethal parasitic infection with neurological involvement. Examination of the cerebrospinal fluid (CSF) plays an essential role in diagnosis, selection of treatment and post‐treatment follow‐up. This paper reviews clinical presentation, diagnosis and treatment of the disease, with emphasis on CSF characteristics and interpretation of the CSF results for therapeutic decision and post‐treatment follow‐up.
Early infant growth monitoring – time well spent?
Authors: Ross Amanda , English Mike 
Published: April 2005

SummaryBackground  In sub‐Saharan Africa, growth monitoring for every infant consumes time and resources with no evidence of any benefits. We consider an alternative pragmatic approach which provides scheduled monitoring for low birth weight infants only, and takes advantage of non‐routine clinic visits for normal birth weight infants. We investigate the implications for the number of weighing episodes and performance as a screening tool using data from a cohort study of infants followed‐up from birth to 98 days.Methods  Babies delivered in a Kenyan district hospital and enrolled in a birth cohort were weighed at birth and at follow‐up visits coinciding with their immunizations at 6, 10 and 14 weeks. Episodes of illness resulting in clinic visits, hospital admissions or death were identified and recorded.Results  Four‐fifths (81%) of the 2210 babies weighed 2500 g or more at birth, of whom 133 (7%) were admitted to hospital or died before 14 weeks of age. 85% of the deaths and 67% of admissions occurred within 3 weeks of birth. Most babies weighing 2500 g or more and who had weight measurements grew well. Only 4% of infants were exclusively breastfed at 14 weeks of age. Neither universal nor pragmatic growth monitoring was a good screening tool among this group of infants for episodes of illness in the short‐term. Pragmatic monitoring would involve 72% fewer weighing episodes.Conclusions  A pragmatic approach in early infancy would not represent a major change in policy, would appear to have no disadvantages and would probably increase the time available for implementing interventions of greater benefit such as breastfeeding promotion.
Ecological covariates of Ascaris lumbricoides infection in schoolchildren from rural KwaZulu‐Natal, South Africa
Authors: Saathoff Elmar , Olsen Annette , Kvalsvig Jane D. , Appleton Chris C. , Sharp Brian , Kleinschmidt Immo 
Published: April 2005

SummaryObjectives  To identify environmental factors that could serve to predict Ascaris lumbricoides infection patterns and thus guide control efforts in the absence of epidemiological information; to assess whether A. lumbricoides infection is positively associated with the soil clay content.Methods  Information on A. lumbricoides infection and re‐infection in a cohort of primary schoolchildren and interview data on their socioeconomic background and behaviour were combined with environmental data using a geographical information system (GIS). Multivariate models served to explore the covariation of environmental and infection patterns adjusted for possible confounders.Results  Prevalence maps and spatial statistics revealed considerable spatial clustering of infection in the small study area. Logistic multivariate regression models showed strong positive associations of infection with vegetation density measured as the normalized difference vegetation index (NDVI) at baseline [odds ratio (OR) for a 10% increase: 1.82; 95% confidence interval (95% CI): 1.24–2.68; P = 0.002] and after re‐infection (OR: 2.22; 95% CI: 1.71–2.87; P < 0.001). We also found a strong negative association of re‐infection with the sun exposure of the soil surface as estimated from digital elevation models (OR: 0.78; 95% CI: 0.88; P < 0.001). The soil clay content was only moderately positively associated with infection and re‐infection. Socioeconomic and behavioural variables, although correlated with A. lumbricoides infection, did not appear to confound the above associations in the demographically homogeneous study area. Spatial analysis of the model residuals suggested that as the models accounted for most of the spatial pattern, the model standard errors should not be affected by spatial clustering.Conclusion  NDVI seems to have a high potential for the prediction of A. lumbricoides infection as it was strongly associated with infection patterns in the study area. Further advantages are that NDVI information is easy to use, affordable and available with global coverage.
A pleasing consequence of Norway rat eradication: two shrew species recover
Authors: Pascal Michel , Siorat François , Lorvelec Olivier , Yésou Pierre , Simberloff Daniel 
Published: April 2005

ABSTRACTFour to 10 years after the successful eradication of the Norway rat (Rattus norvegicus) from three islands of the Sept–Îles Archipelago and one in the Molène Archipelago (Brittany, France), the abundance index of the lesser white‐toothed shrew (Crocidura suaveolens) increased by factors of 7–25, depending on the island and the year. Moreover, in the same region, the abundance index of the greater white‐toothed shrew (Crocidura russula) on Tomé Island increased by factors of 9 and 17, one and two years after the Norway rat eradication, respectively. The maximum variation of the abundance index for the lesser white‐toothed shrew during seven years on the rat‐free island of Béniguet in the same region was a factor of only 2.5. Moreover, the distribution of the lesser white‐toothed shrew on Bono island, restricted before the eradication to two steep areas with few rats, increased and encompassed virtually the entire island four years after rats disappeared. These results suggest strong detrimental interactions between the introduced Norway rat and the two Crocidura shrew species on temperate oceanic islands. However, our data do not indicate the ecological mechanisms at work in these interactions. The main reason this shrew recovery was detected after rat eradication was the inclusion in the eradication protocol of the evaluation of impacts on the local biota of eliminating alien species. The rigor of the sampling procedure was also crucial to this discovery. This example demonstrates that an eradication operation can be extremely useful for both scientists and managers if it is planned as a research project.