bluuebunny/crossref_metadata_2025_split huggingface dataset:
Small lakes dominate a random sample of regional lake characteristics
Authors: HANSON PAUL C. , CARPENTER STEPHEN R. , CARDILLE JEFFREY A. , COE MICHAEL T. , WINSLOW LUKE A. 
Published: February 2007

Summary1. Lakes are a prominent feature of the Northern Highland Lake District (NHLD) of Wisconsin, covering 13% of the landscape. Summarising the physical, chemical, or biological nature of NHLD lakes at a regional scale requires a representative sample of the full size distributions of lakes. In this study, we selected at random 168 lakes from the full size distribution of lakes in the NHLD and sampled each lake for a broad suite of limnological variables.2. Most lakes were small. The median lake area was 1.1 ha, however, half of the surface area of water was in a relatively small number of lakes larger than 162 ha. Smaller lakes tended to be low in dissolved inorganic carbon (DIC) and high in dissolved organic carbon (DOC). Inclusion of small lakes (<4 ha) in the survey resulted in an acid neutralising capacity (ANC) median (76.5 μEq L−1) much lower than previous estimates, and a DOC median (10.1 mg L−1) about 50% higher than it would have been without the smaller lakes. Unlike DOC, total P tended to be evenly distributed across lake sizes.3. The implications of these findings are that regional summaries of lake characteristics for the NHLD are influenced by the inclusion of small lakes in the sample, even though most of the water surface area is in lakes larger than 162 ha. Excluding small lakes introduces bias in the estimates of organic carbon and inorganic carbon values, for example. Similar biases may be introduced for lake characteristics at the global scale if small lakes are not sampled, because the size distribution of lakes globally is dominated in number by small lakes.
Planktonic phosphorus pool sizes and cycling efficiency in coastal and interior British Columbia lakes
Authors: NOWLIN WESTON H. , DAVIES JOHN‐MARK , MAZUMDER ASIT 
Published: February 2007

Summary1. Limnologists have long acknowledged the importance of phosphorus (P) in determining the organism biomass and productivity of lake ecosystems. Despite a relatively large number of studies that have examined P cycling in lake ecosystems, there remain several substantial methodological issues that have impeded our understanding of P cycling in limnetic plankton communities. Two critical issues confronting ecologists are (1) a lack of precise measurements of the dissolved inorganic phosphorus (PO) and (2) accurate or complete measurements of dissolved P regeneration rates by plankton communities.2. Here, we examine patterns of epilimnetic planktonic P pool sizes and turnover rates in eight lakes in British Columbia, Canada over a 2‐year period. We determine the concentrations and turnover times of P in various planktonic compartments (dissolved and various planktonic size fractions), using recently developed methods for estimating phosphate concentration and planktonic regeneration rates.3. The pico‐ and nanoplankton size fraction (0.2–20 μm) played a central role in planktonic P cycling in lakes examined by this study. On average across lakes, pico‐ and nanoplankton contained >60% of the planktonic P, accounted for >90% PO uptake, and contributed 50% of the plankton community dissolved P regeneration rate.4. PO concentrations determined by steady state bioassays (ssPO) were extremely low (87–611 pmol L−1) and were 2–3 orders of magnitude less than simultaneously measured colorimetric soluble reactive phosphorus estimates. Lake ssPO concentrations increased linearly with total phosphorus (TP), and the slope of this relationship was approximately 1, indicating that PO remained a consistent proportion of the TP pool across a range of TP concentrations.5. Turnover rates of the total planktonic P pool and the <20 μm pool became more rapid with increasing lake TP, indicating that, according to this metric, planktonic P cycling efficiency increased with TP concentrations. We also detected a significant relationship between particulate phosphorus (PP) <20 μm turnover time and seston N : P ratios, with PP <20 μm turnover times becoming slower with increasing seston N : P. These findings suggest that long‐standing conceptual models of nutrient cycling that predict slower cycling rates and decreasing cycling efficiency with increasing TP concentrations require further empirical examination. We postulate that patterns in lake P turnover and cycling efficiency are a result of complex interactions between plankton biomass and composition, and the ratios of multiple nutrients (C, N, P), rather than solely a function of the TP pool.
Variation in sperm size within and between ejaculates in a cockroach
Authors: HARRIS W. E. , MOORE A. J. , MOORE P. J. 
Published: February 2007

Summary

Interspecific diversity in the morphology of animal sperm suggests adaptive evolutionary changes in size and structure. Little attention has been directed at patterns of intraspecific phenotypic variation in sperm morphology, although such variation is a prerequisite for the extreme diversity seen among male gametes. Despite well‐developed sperm competition theory providing a basis for exploring how variation in sperm morphology may affect male fitness, the patterns of variation in sperm morphology remain unclear for most species.
We report systematic size variation in sperm length among different males and between successive ejaculates within the same male in the cockroach Nauphoeta cinerea. Both flagellum length and mid‐piece length decreased between the first and second ejaculate. However, within the same ejaculate the sperm head (acrosome and nucleus), midpiece (centriole adjunct region) and tail length exhibited less variation than that present between males for both first and second ejaculates.
Our findings, combined with previous studies, suggest a focus on episodes of selection and lifetime selection on ejaculates may be instructive in understanding the selective forces influencing sperm evolution in a predictive framework.
Disruption of theWolbachiasurface protein genewspBby a transposable element in mosquitoes of theCulex pipienscomplex (Diptera, Culicidae)
Authors: Sanogo Y. O. , Dobson S. L. , Bordenstein S. R. , Novak R. J. 
Published: February 2007

AbstractCulex pipiens quinquefasciatusSay andCulex pipiens pipiensLinnaeus are sibling species incriminated as important vectors of emerging and re‐emerging infectious diseases worldwide. The two forms differ little morphologically and are differentiated mainly based upon ecological, behavioural, physiological and genetic traits. Within the North American zone of sympatry, populations ofCx. p. quinquefasciatusandCx. p. pipiensundergo extensive introgression and hybrid forms have been reported in nature. BothCx. p. quinquefasciatusandCx. p. pipiensare infected with the endosymbiotic bacteriaWolbachia pipientis.Here, we report the presence of a transposable element belonging to the IS256 family (IS256wPip) associated withWolbachiain bothCx. p. quinquefasciatusandCx. p. pipienspopulations. Using reverse transcriptase PCR and sequence analysis, we show that IS256wPip has disrupted thewspBlocus, a paralogue of theWolbachiaouter membrane protein (wspA) gene. The inactivation of thewspBappears to be specific toCx. p. quinquefasciatusand to hybrids of the two forms, and was not observed in the surveyedCx. p. pipiensmosquitoes. Our results support the hypothesis of a different origin of North AmericanCx. p. quinquefasciatusandCx. p. pipienspopulations. The flux of mobile genetic elements in theWolbachiawPip genome could explain the high level of crossing types observed among differentCulexpopulations. The insertion of IS256wPip intowspBmay comprise a genetic candidate for discriminatingWolbachiasymbionts inCulex.
Ixodes ticks belonging to the Ixodes ricinus complex encode a family of anticomplement proteins
Authors: Daix V. , Schroeder H. , Praet N. , Georgin J.‐P. , Chiappino I. , Gillet L. , De Fays K. , Decrem Y. , Leboulle G. , Godfroid E. , Bollen A. , Pastoret P.‐P. , Gern L. , Sharp P. M. , Vanderplasschen A. 
Published: February 2007

AbstractThe alternative pathway of complement is an important innate defence against pathogens including ticks. This component of the immune system has selected for pathogens that have evolved countermeasures. Recently, a salivary protein able to inhibit the alternative pathway was cloned from the American tick Ixodes scapularis (Valenzuela et al., 2000; J. Biol. Chem. 275, 18717–18723). Here, we isolated two different sequences, similar to Isac, from the transcriptome of I. ricinus salivary glands. Expression of these sequences revealed that they both encode secreted proteins able to inhibit the complement alternative pathway. These proteins, called I. ricinus anticomplement (IRAC) protein I and II, are coexpressed constitutively in I. ricinus salivary glands and are upregulated during blood feeding. Also, we demonstrated that they are the products of different genes and not of alleles of the same locus. Finally, phylogenetic analyses demonstrate that ticks belonging to the Ixodes ricinus complex encode a family of relatively small anticomplement molecules undergoing diversification by positive Darwinian selection.
Microsatellite flanking region similarities among different loci within insect species
Authors: Meglécz E. , Anderson S. J. , Bourguet D. , Butcher R. , Caldas A. , Cassel‐Lundhagen A. , D’Acier A. C. , Dawson D. A. , Faure N. , Fauvelot C. , Franck P. , Harper G. , Keyghobadi N. , Kluetsch C. , Muthulakshmi M. , Nagaraju J. , Patt A. , Péténian F. , Silvain J.‐F. , Wilcock H. R. 
Published: February 2007

AbstractAlthough microsatellites are ubiquitous in eukaryota, the number of available markers varies strongly among taxa. This meta‐analysis was conducted on 32 insect species. Sequences were obtained from two assembled whole genomes, whole genome shotgun (WGS) sequences from 10 species and screening partial genomic libraries for microsatellites from 23 species. We have demonstrated: (1) strong differences in the abundance of microsatellites among species; (2) that microsatellites within species are often grouped into families based on similarities in their flanking sequences; (3) that the proportion of microsatellites grouped into families varies strongly among taxa; and (4) that microsatellite families were significantly more often associated with transposable elements – or their remnants – than unique microsatellite sequences.
Deposits and physical properties of pyroclastic density currents during complex Subplinian eruptions: the AD 472 (Pollena) eruption of Somma‐Vesuvius, Italy
Authors: SULPIZIO ROBERTO , MELE DANIELA , DELLINO PIERFRANCESCO , LA VOLPE LUIGI 
Published: February 2007

AbstractSmall‐scale pyroclastic density currents (PDCs) associated with the AD 472 (Pollena) eruption of Somma‐Vesuvius, Italy, were generated by both magmatic and phreatomagmatic explosive fragmentation. The resulting deposits were emplaced under flow boundary conditions dominated by varying combinations of grain interaction, fluid escape and traction processes. Stratigraphic and lithofacies analysis of these PDCs offers a new perspective on the en masse versus progressive aggradation debate for PDC deposition. In particular, the analyses indicate that PDCs were density stratified with a basal underflow dominated by grain interactions. The underflows comprised trains of self‐organized granular pulses of variable thickness and magnitude, depending on the overall particle concentration and fluid turbulence. A change in gradient between the upper and lower slopes of the volcano promoted deposition and the different pulses aggraded sequentially (stepwise). In this model each pulse stops en masse and the whole deposit aggrades progressively. Particle concentration, density, mean velocity, and flow height were assessed for the studied PDCs using differaent methods for massive and stratified deposits. The calculated mobility of the flows was 0·2 to 0·3, in the expected range for small‐scale PDCs.
Palaeoceanographic controls on reef deposition: the Messinian Cariatiz reef (Sorbas Basin, Almería, SE Spain)
Authors: SÁNCHEZ‐ALMAZO I. M. , BRAGA J. C. , DINARÈS‐TURELL J. , MARTÍN J. M. , SPIRO B. 
Published: February 2007

AbstractThe Cariatiz section lies at the toe of the palaeoslope of the Messinian Cariatiz fringing reef, at the northern margin of the Neogene Sorbas Basin in SE Spain. Distal‐slope reef deposits in the upper part of the section can be traced laterally to the reef core of the last episodes of reef progradation. The underlying deposits are alternating diatomitic marl, marl and silty marl that intercalate with sandstone beds. Combined lithological changes, variations in proportions of warm‐water planktic foraminifera and δ18O values suggest that at least seven, probably precessional, cycles are recorded throughout the Cariatiz section. The correlation of seven cycles in the pelagic deposits to seven reef progradation cycles, and associated vertical shifts in reef facies, indicates relative sea‐level oscillations of several tens of metres. Biostratigraphic and palaeomagnetic data suggest that both the Cariatiz section and the fringing reef formed during the reverse polarity Chron C3r. Surface‐water temperatures seem to be the major factor controlling carbonate production in the reef system. Deposition of bioclastic calcirudite and calcarenite, with no active coral growth, took place at the lowest sea‐level within each reef cycle during temperature minima within each precessional cycle. Porites framework and reef‐slope deposits with Halimeda gravel, in contrast, formed during temperature rises and thermal maxima within precessional cycles.
Identification of two novel alleles HLA‐B*3569 and ‐B*4450 and confirmation of HLA‐A*2631 in the Brazilian population†
Authors: Abdeen H. , McErlean C. , Moraes M. E. , Romero M. , Marques S. B. , Goncales A. C. , Guariento E. G. , Middleton D. 
Published: February 2007

AbstractTwo novel alleles, human leukocyte antigen (HLA)‐B*3569, ‐B*4450 and a confirmatory sequence of HLA‐A*2631 were identified during a routine typing for the Brazilian Bone Marrow Donor Registry. Sequence analysis of coding exons 2 and 3 revealed a single nucleotide substitution in HLA‐B*3569 and two single nucleotide substitutions in HLA‐B*4450, compared with closely related alleles. At the protein level, these substitutions result in a change of a single amino acid residue in each of HLA‐B*3569 and ‐B*4450 at positions 74 (Arg > Pro) and 80 (Thr > Ile), respectively. These variations are located in the highly polymorphic region at the end of the α1 domain of the HLA molecule. It appears that HLA‐B*3569 arose from the analogous HLA‐B*3510 through a point mutation. However, HLA‐B*4450 may have arisen from HLA‐B*440301 and ‐B*4425 by gene conversion.
MIC gene polymorphism and haplotype diversity in rhesus macaques
Authors: Doxiadis G. G. M. , Heijmans C. M. , Otting N. , Bontrop R. E. 
Published: February 2007

AbstractRhesus macaques (Macaca mulatta) mainly originating from India were analysed for their major histocompatibility complex class I‐related (MIC) gene repertoire. Thus far, three distinct genes, designated MIC1, MIC2 and MIC3, have been identified in the rhesus macaque. In addition, an MICD pseudogene has been described mapping apart from the other loci in a telomeric direction. Genomic comparisons and the presence of a characteristic microsatellite in exon 5 suggest that the MIC1 gene is the equivalent of the human MICA gene. Hence, the MIC2 gene, lacking the microsatellite – as do humans –, is considered to be the equivalent of human MICB. The MIC3 gene, a hybrid of MICA and MICB, seems to be generated by a crossing‐over event with one breakpoint in intron 3 and accordingly is named MICA/B. Apart from their human counterparts, MICA, MICB and MICA/B cluster in separate branches in the phylogenetic tree, confirming the hybrid character of the MICA/B gene. Population analyses have shown that the various genes display polymorphism, and six MICA, five MICB and three MICA/B alleles have been identified. In the panel of homozygous typing cells, two distinct haplotype configurations have been defined by segregation analyses. Each haplotype comprises an MICB gene in conjunction with either an MICA or an MICA/B gene. Furthermore, the presence of a polymorphic microsatellite in the MICA and MICA/B alleles facilitates speedy and accurate haplotyping.
The distribution ofcopia‐type retrotransposons and the evolutionary history of tomato and related wild species
Authors: TAM S. M. , CAUSSE M. , GARCHERY C. , BURCK H. , MHIRI C. , GRANDBASTIEN M.‐A. 
Published: February 2007

AbstractRetrotransposons are mobile genetic elements that amplify throughout the genome and may be important contributors of genetic diversity. Their distribution is influenced by element behaviour and host‐driven controls. We analysed the distribution of threecopia‐type retrotransposons, ToRTL1, T135 and Tnt1 using sequence‐specific amplification polymorphism in self‐compatible (SC) and incompatible (SI) species ofSolanumsubsectionLycopersicon, and genetically mapped polymorphic insertions inS. lycopersicum(tomato). The majority of polymorphic insertions (61%) are located in centromeric regions of the tomato genome. A significant positive relationship was detected between insertion polymorphisms and mating system, independent of selection as most insertions were found to be neutral. As insertion patterns successfully inferred interspecific relationships ofSolanumsubsectionLycopersicon, our results suggest that the distribution of ToRTL1, T135 and Tnt1 may essentially be determined by selection removing strongly deleterious insertions, with genetic drift and mating system, but not recombination rate, playing important roles.
A screen for immunity genes evolving under positive selection in Drosophila
Authors: JIGGINS F. M. , KIM K. W. 
Published: February 2007

AbstractGenes involved in the immune system tend to have higher rates of adaptive evolution than other genes in the genome, probably because they are coevolving with pathogens. We have screened a sample of Drosophila genes to identify those evolving under positive selection. First, we identified rapidly evolving immunity genes by comparing 140 loci in Drosophila erecta and D. yakuba. Secondly, we resequenced 23 of the fastest evolving genes from the independent species pair D. melanogaster and D. simulans, and identified those under positive selection using a McDonald–Kreitman test. There was strong evidence of adaptive evolution in two serine proteases (persephone and spirit) and a homolog of the Anopheles serpin SRPN6, and weaker evidence in another serine protease and the death domain protein dFADD. These results add to mounting evidence that immune signalling pathway molecules often evolve rapidly, possibly because they are sites of host–parasite coevolution.
The evolution of conspecific gamete precedence and its effect on reinforcement
Authors: LORCH P. D. , SERVEDIO M. R. 
Published: February 2007

AbstractConspecific gamete precedence, the usage of conspecific sperm by a female that mates with both a conspecific and a heterospecific male, has been found in many taxa. We construct a population genetic model to examine the evolution of conspecific gamete precedence and its coevolution with premating isolation in the process of reinforcement. Our findings suggest that conspecific gamete precedence can evolve via a process very similar to reinforcement. We explore the nature of the selection against hybridization necessary to drive this evolution. Moreover, our results confirm the prediction ofMarshallet al.(Trends Ecol. Evol.2002;17:558–563)that conspecific gamete precedence will inhibit the evolution of reinforcement between two species. We further find that reinforcement will inhibit the evolution of conspecific gamete precedence. Both reinforcement and conspecific gamete precedence increase reproductive isolation and contribute to the process of speciation. We discuss factors that may affect which of these phenomena are likely to become predominant between incipient species.
Inference of parasite local adaptation using two different fitness components
Authors: REFARDT D. , EBERT D. 
Published: February 2007

AbstractEstimating parasite fitness is central to studies aiming to understand parasite evolution. Theoretical models generally use the basic reproductive rate R0 to express fitness, yet it is very difficult to quantify R0 empirically and experimental studies often use fitness components such as infection intensity or infectivity as substitutes. These surrogate measures may be biased in several ways. We assessed local adaptation of the microsporidium Ordospora colligata to its host, the crustacean Daphnia magna using two different parasite fitness components: infection persistence over several host generations in experimental populations and infection intensity in individual hosts. We argue that infection persistence is a close estimator of R0, whereas infection intensity measures only a component of it. Both measures show a pattern that is consistent with parasite local adaptation and they correlate positively. However, several inconsistencies between them suggest that infection intensity may at times provide an inadequate estimate of parasite fitness.
β‐Aminobutyric Acid‐induced Resistance in Brassica juncea against the Necrotrophic Pathogen Alternaria brassicae
Authors: Kamble A. , Bhargava S. 
Published: February 2007

Abstract β‐Aminobutyric acid (BABA) pretreatment of Brassica plants protected them against the necrotrophic pathogen Alternaria brassicae. The achieved resistance level was much higher than that seen after salicylic acid (SA) and jasmonic acid (JA) pretreatments. BABA pretreatment to the leaves, 1 day before inoculation, led to an inhibition of the oxidative burst and a decrease in SA levels, but did not influence lipoxygenase activity nor cause callose deposition at the site of inoculation. Expression of two marker genes of the SA and JA pathways, namely PR1 and PDF1.2, was enhanced in response to BABA pretreatment. Our results indicate that BABA‐induced resistance is mediated through an enhanced expression of pathogenesis‐related protein genes, independent of SA and JA accumulation.
Patterns of growth in cold‐seep vestimenferans including Seepiophila jonesi: a second species of long‐lived tubeworm
Authors: Cordes Erik E. , Bergquist Derk C. , Redding Meredith L. , Fisher Charles R. 
Published: February 2007

Abstract Seepiophila jonesi is a vestimentiferan tubeworm (Siboglinidae: Polychaeta) inhabiting the cold seeps of the upper slope of the Gulf of Mexico. It commonly co‐occurs with Lamellibrachia luymesi, which is among the most long‐lived non‐clonal animals known. The growth pattern of S. jonesi is best described by a model including a size‐specific probability of growth and an average growth rate that does not vary with individual size. This model, based on growth data from in situ staining and collection approximately 1 year later, predicts that S. jonesi is very slow growing and may attain ages comparable with L. luymesi. The efficacy of this model in describing L. luymesi growth rate was assessed, but the previously employed model of declining growth rate with individual size provided the better fit to the empirical data. Comparisons of both S. jonesi and L. luymesi growth rates among sites and among aggregations within a site indicate that there is some degree of habitat variability contributing to differences in growth rates. However, position of the anterior end of the worm within an aggregation did not have a significant effect on growth rate in comparisons among groups of L. luymesi from different distances from the center of an aggregation. The evolution of longevity in these species of vestimentiferans was favored by the relative stability of the seep habitat and sulfide sources, in contrast to the hydrothermal vent environment inhabited by relatively short‐lived and fast‐growing vestimentiferan species.