bluuebunny/crossref_metadata_2025_split huggingface dataset:
Temperature effects on seed maturity and dormancy cycles in an aquatic annual, Najas marina, at the edge of its range
Authors: HANDLEY RICHARD J. , DAVY ANTHONY J. 
Published: October 2005

Summary

Najas marina is a summer annual of shallow lakes that reaches its distributional limit in the Norfolk Broads of eastern England. Seeds are shed in autumn and overwinter in lake sediments.
We investigated the influence of growing‐season length on seed maturity and germinability and the cumulative effects of winter temperatures on patterns of germinability. Seeds were stratified for up to 1 year and tested for germinability at 4‐week intervals. Data‐loggers recorded temperatures simultaneously at the field site and in the cold room. Cumulative temperature below a threshold (thermal time) was used to relate behaviour in cold storage to phenology.
Most seeds were dormant at collection. Cold storage of imbibed seed resulted in loss of dormancy. The proportion of non‐dormant seeds peaked after a cold treatment equivalent to one winter, i.e. coinciding with favourable temperatures for germination in the field. Continued cold stratification resulted in a cycle of secondary dormancy and its subsequent relief; the thermal time characterizing the second, lower, peak in germinability coincided approximately with that attained in the field in the second spring after collection.
Shortening the growing season of Najas marina, by collecting material before natural senescence was complete, reduced the proportion of mature seeds, lowered average germinability and increased germination times.
The thermal capacity of water bodies causes a lag in spring warming, whereas declining light becomes limiting in autumn. Najas marina is crucially dependent on the length of growing season to produce sufficient viable seed. A low‐temperature requirement to break seed dormancy prevents inappropriate autumn germination. In a prolonged winter (necessarily followed by a shorter growing season), a significant proportion of seed would go into secondary dormancy and remain in the seed bank until the second spring.
In annual plants, such requirements for warm summers and cold winters could contribute to a continental‐climate distribution in northern Europe. In the case of Najas marina this might explain its limit at the eastern extremity of England and thus its rarity.
Spatial genetic structure links between soil seed banks and above‐ground populations ofPrimula modestain subalpine grassland
Authors: SHIMONO A. , UENO S. , TSUMURA Y. , WASHITANI I. 
Published: October 2005

SummaryThe spatial genetic structure of soil seed banks establishes the initial template for development of spatial genetic structure in above‐ground plants, but is rarely evaluated.We used kinship coefficients to analyse the fine‐scale spatial genetic autocorrelation of plants and of seed banks from different soil depths forPrimula modestaat a subalpine fen site on Mt Asama, central Japan.The spatial genetic structure of surface seeds (0–1 cm depth) was significant, while deeper seeds (1–5 cm depth) had no significant genetic structure. We also detected a more pronounced spatial genetic association between the surface seeds and flowering genets than between the deeper seeds and flowering genets.These results suggest that the surface seed bank accounts for a large proportion of the previous season's seed dispersal and therefore represents the transient seed bank, whereas the deeper (persistent) seed bank pools the reproductive output of multiple generations.Directional analysis indicated that secondary dispersal by running water modifies the spatial genetic structure and extends dispersal distances. Over time, this may impact on the spatial pattern of soil seeds, possibly accounting for the absence of spatial genetic structure in deeper seeds.Emerging seedlings and flowering ramets were strongly clustered together at distances up to 20 cm. Surviving seedlings were aggregated at short distances because of the patchy spatial distribution of safe sites for establishment, allowing development and strengthening of the marked fine‐scale spatial genetic structure.
Spatial and temporal scaling of intercellular CO2concentration in a temperate rain forest dominated byDacrydium cupressinumin New Zealand
Authors: TISSUE DAVID T. , BARBOUR MARGARET M. , HUNT JOHN E. , TURNBULL MATTHEW H. , GRIFFIN KEVIN L. , WALCROFT ADRIAN S. , WHITEHEAD DAVID 
Published: October 2005

ABSTRACTSeven methods, including measurements of photosynthesis (A) and stomatal conductance (gs), carbon isotope discrimination, ecosystem CO2and water vapour exchange using eddy covariance and the use of a multilayer canopy model and ecosystem Keeling plots, were employed to derive estimates of intercellular CO2concentration (Ci) across a range of spatial and temporal scales in a low productivity rain forest ecosystem dominated by the coniferDacrydium cupressinumLamb. in New Zealand. Estimates of shoot and canopyCiacross temporal scales ranging from minutes to years were remarkably similar (range of 274–294 µmol mol−1). The gradual increase in shootCiwith depth in the canopy was more likely attributable to decreases inAresulting from lower irradiance (Q) than to increases ingsdue to changes in air saturation deficit (D). The lack of marked vertical gradients inAandgsat saturatingQthrough the canopy and the low seasonal variability in environmental conditions contributed to the efficacy of scalingCi. However, the canopyCiestimate calculated from the carbon isotope composition of respired ecosystem CO2(δ 13CR; 236 µmol mol−1) was much lower than other estimates of canopyCi. Partitioningδ 13CRinto four components (soil, roots, litter and foliage) indicated root respiration as the dominant (> 50%) contributor toδ 13CR. Variable time lags and differences in isotopic composition during photosynthesis and respiration make the direct estimation of canopyCifromδ 13CRproblematic.
Growth and ethylene evolution by shade and sun ecotypes of Stellaria longipes in response to varied light quality and irradiance
Authors: KUREPIN LEONID V. , WALTON LINDA J. , REID DAVID M. , PHARIS RICHARD P. , CHINNAPPA C. C. 
Published: October 2005

ABSTRACTPlants growing in the shade receive both low light irradiance and light enriched in far red (FR) (i.e. light with a low red (R) to FR ratio). In an attempt to uncouple the R/FR ratio effects from light irradiance effects, we utilized Stellaria longipes because this species has two distinct natural population ecotypes, alpine (dwarf) and prairie (tall). The alpine population occupies the open, sun habitat. By contrast, the prairie population grows in the shade of other plants. Both ‘sun’ and ‘shade’ ecotypes responded with increased stem elongation responses under low irradiance, relative to growth under ‘normal’ irradiance, and this increased growth was proportionally similar. However, only the shade ecotype had increased shoot elongation in response to a low R/FR ratio. By contrast, the sun ecotype showed increased stem elongation in response to increasing R/FR ratio. Varying the R/FR ratios had no significant effect on ethylene evolution in either sun or shade ecotype. Under low irradiance, only the sun ecotype showed a significantly changed (decreased) ethylene evolution. We conclude that R/FR ratio and irradiance both regulate growth, and that irradiance can also influence ethylene evolution of the sun ecotype. By contrast, R/FR ratio and irradiance, while having profound influences on growth of the shade ecotype, do not appear to regulate these growth changes via effects on ethylene production.
Spatial heterogeneity and the stability of host-parasite coexistence
Authors: Brockhurst M. A. , Buckling A , Rainey P. B. 
Published: October 2005

Abstract
Spatially heterogeneous environments can theoretically promote more stable coexistence of hosts and parasites by reducing the risk of parasite attack either through providing permanent spatial refuges or through providing ephemeral refuges by reducing dispersal. In experimental populations of Pseudomonas aeruginosa and the bacteriophage PP7, spatial heterogeneity promoted stable coexistence of host and parasite, while coexistence was significantly less stable in the homogeneous environment. Phage populations were found to be persisting on subpopulations of sensitive bacteria. Transferring populations to fresh microcosms every 24 h prevented the development of permanent spatial refuges. However, the lower dispersal rates in the heterogeneous environment were found to reduce parasite transmission thereby creating ephemeral refuges from phage attack. These results suggest that spatial heterogeneity can stabilize an otherwise unstable host-parasite interaction even in the absence of permanent spatial refuges.
Parvovirus B19 VP2‐Proteins Produced in Saccharomyces cerevisiae: Comparison with VP2‐Particles Produced by Baculovirus‐Derived Vectors
Authors: Lowin T. , Raab U. , Schroeder J. , Franssila R. , Modrow S. 
Published: October 2005

SummaryThe capsids of human parvovirus B19 consist of two structural proteins, the minor‐capsid protein VP1 and the major‐capsid protein VP2. The latter which constitutes for 95% of the capsid are able to form virus‐like particles (VLPs) in yeast without the presence of VP1‐proteins. VP2‐proteins produced in Saccharomyces cerevisiae have the capacity to form VLPs in the absence of VP1‐proteins. These yeast‐derived VLPs resemble native virus or recombinant VP2–VLPs produced by baculovirus systems in respect of size, molecular weight and of antigenicity as shown by antigen‐capture ELISA and T‐cell proliferation tests. Regarding costs, yield and ease of handling particle production in yeast represents an alternative to the recombinant baculovirus expression system which is so far the source for VP2–VLPs of human parvovirus B19.
Human Parvovirus B19 Serology and Avidity Using a Combination of Recombinant Antigens Enables a Differentiated Picture of the Current State of Infection
Authors: Pfrepper K.‐I. , Enders M. , Motz M. 
Published: October 2005

SummaryIn order to improve serodiagnostic methods for the determination of the state of human parovirus B19 infection, a new test system, recomLine Parvovirus, based on the use of recombinant antigens, has been developed and evaluated. The test system combines the advantages of enzyme‐linked immunosorbent assay (ELISA) methods with those of the Western blot technique. For the recombinant line assay, five antigens of human parvovirus B19 that were recombinantly produced in Escherichia coli were applied directly on nitrocellulose membranes: VP2, the aminoterminal and the carboxyterminal domain of VP1 (VP‐N and VP‐C), VP‐1S another fragment of VP‐N and NS1. In addition, empty virus particles isolated from eukaryotic cell cultures were also applied. The recombinant‐line assay was used to detect human IgG and IgM antibodies directed against human parvovirus B19. In addition, the avidity of the IgG antibodies was investigated. The recombinant line assay was evaluated using 87 human serum samples of patients recently infected with human parvovirus B19 including 10 samples of three infection time courses and 100 serum samples of healthy blood donors. All results were compared with commercially available ELISAs. In the case of discrepancies, Western blot analysis was performed. The data revealed the recombinant line assay to be highly sensitive and specific. The individual determination of the human immune response against several recombinant antigens covering the structural proteins of human parvovirus B19 gives a deeper insight into the actual status of infection. In addition, the determination of IgG avidity against these individual recombinant antigens enables a more precise and differentiated picture of the infection event.
Tissue Distribution of Two Field Isolates and Two Vaccine Strains of Porcine Parvovirus in Foetal Organs after Experimental Infection of Pregnant Sows as Determined by Real‐time PCR
Authors: Wilhelm S. , Zeeuw E. J. L. , Selbitz H.‐J. , Truyen U. 
Published: October 2005

SummaryThe aim of this study was to investigate the tissue distribution of two different field isolates and two vaccine strains of porcine parvoviruses (PPV) in infected piglets after transplacental infection. The viral load in 10 different foetal organs was determined by real‐time polymerase chain reaction assays with SYBR® Green targeting the viral VP2 gene and the genomic c‐myc gene in 12 foetuses. The viral load in foetal tissues differed greatly among the different parvoviruses. Between one virulent field isolate compared with the other field isolate and the vaccine strains, the detected viral copy number differed in an order of magnitude of 109. The virulent isolate contained PPV in all 10 organs with viral loads varying between 1011 and 1015 per 106 cells. Concerning the other field isolate and the two vaccine strains, if PPV was detected, in most of the cases the highest viral load was found in foetal kidneys with a maximum viral load of 103 per 106 cells. Additionally, PPV was found in the heart of one foetus, in the liver and duodenum of one foetus and in the thymus of one foetus with viral loads varying between 102.1 and 103.5 per 106 cells. In completely mummified foetuses with no discriminable organs of foetuses infected with the vaccine strains and the less virulent isolate, PPV was present in very low amounts or even below the detection limit.
Quantitative, longitudinal profiling of the primate fecal microbiota reveals idiosyncratic, dynamic communities
Authors: Wireman Joy , Lowe Mary , Spiro Alex , Zhang Yu‐Zhong , Sornborger Andrew , Summers Anne O. 
Published: October 2005

SummaryWe used slot blot hybridization, quantitative polymerase chain reaction (qPCR), and flow cytometry microarrays to quantify specific 16S rDNAs in weekly fecal specimens from four monkeys housed in a research vivarium for periods ranging from five to 8 months. Even in these uniformly housed and fed animals the gut microbiota is idiosyncratic, very dynamic on short timescales, and shows significant positive and negative correlations among some bacteria as well as responses to heavy metal exposure. The relative quantification (fmol targets per total fmol bacterial 16S rDNA) afforded by flow cytometry microarrays agreed well with the absolute quantification (nanogram of target DNA per nanogram of fecal DNA) afforded by slot blots and qPCR. We also noted strengths and weaknesses in inter‐method comparisons for DNA‐based quantification of these complex bacterial communities.
The desert of Tataouine: an extreme environment that hosts a wide diversity of microorganisms and radiotolerant bacteria
Authors: Chanal Angélique , Chapon Virginie , Benzerara Karim , Barakat Mohamed , Christen Richard , Achouak Wafa , Barras Frédéric , Heulin Thierry 
Published: October 2005

SummaryThe phylogenetic diversity of prokaryotic communities exposed to arid conditions in the hot desert of Tataouine (south Tunisia) was estimated with a combination of a culture and – molecular‐based analysis. Thirty‐one isolates, representative of each dominant morphotypes, were affiliated to Actinobacteria, Firmicutes, Proteobacteria and the CFB group while none related to Archaea. Analysis of 16S rRNA gene libraries revealed the presence of species related to Bacteria and Archaea. Sequences related to Archaea were all affiliated to the non‐thermophilic Crenarchaeota subgroup. Bacterial sequences were dominated by Proteobacteria, Actinobacteria and Acidobacteria; a few sequences were distributed among eight others phyla, including Thermus/Deinococcus relatives. A correlation between tolerance to desiccation and to radiation has been demonstrated for the radiotolerant bacteria Deinococcus radiodurans. Because bacteria living in the hot desert of Tataouine are one way or another tolerant to desiccation, we investigate whether they could also be tolerant to radiation. Exposition of soil samples to intense gamma radiation yields Bacillus, Thermus/Deinococcus and α‐Proteobacteria relatives. Four of these strains correspond to radiotolerant species as revealed by evaluation of the resistance levels of the individual cultures. A detailed analysis of the resistance levels for two Thermus/Deinococcus and two α‐Proteobacteria relatives revealed that they correspond to new radiotolerant species.
Molecular analysis of the rstR and orfU genes of the CTX prophages integrated in the small chromosomes of environmental Vibrio cholerae non‐O1, non‐O139 strains
Authors: Bhattacharya Tanuja , Chatterjee Souvik , Maiti Diganta , Bhadra Rupak K. , Takeda Yoshifumi , Nair G. Balakrish , Nandy Ranjan K. 
Published: October 2005

SummaryThe ctxAB genes encoding cholera toxin, reside in the genome of a filamentous bacteriophage CTXφ. The presence of CTX prophage in non‐epidemic environmental Vibrio cholerae strains is rare. The CTX prophage, the lysogenic form of CTXφ in V. cholerae, is comprised of the ‘RS2’ and the ‘Core’. Analysis of the rstR gene present in the RS2 region of the CTX prophage revealed the presence of new alleles of the prophages in four environmental non‐O1, non‐O139 strains VCE22 (O36), VCE228 (O27), VCE232 (O4) and VCE233 (O27), and the CTX prophages are located in the small chromosomes. Phylogenetic analysis based on the nucleotide sequences of the rstR and orfU (present in the core) genes of these prophages placed them in a single unique cluster, which is distally located compared with that of epidemic V. cholerae O1 strains. Further analysis indicated that the genome of the prophage present in the strain VCE22 is devoid of the ctxAB genes, called pre‐CTX prophage and the strain also possess the toxin‐coregulated pilus protein coding gene tcpA of classical type, another important pathogenicity determining locus of the epidemic V. cholerae strains. Comparative analysis of the nucleotide sequences of the rstR and orfU genes indicated that the pre‐CTX prophage of VCE22 might be the progenitor of new alleles of the CTX prophages present in these environmental strains.
Improved serial analysis of V1 ribosomal sequence tags (SARST‐V1) provides a rapid, comprehensive, sequence‐based characterization of bacterial diversity and community composition
Authors: Yu Zhongtang , Yu Marie , Morrison Mark 
Published: October 2005

SummarySerial analysis of ribosomal sequence tags (SARST) is a recently developed technology that can generate large 16S rRNA gene (rrs) sequence data sets from microbiomes, but there are numerous enzymatic and purification steps required to construct the ribosomal sequence tag (RST) clone libraries. We report here an improved SARST method, which still targets the V1 hypervariable region of rrs genes, but reduces the number of enzymes, oligonucleotides, reagents, and technical steps needed to produce the RST clone libraries. The new method, hereafter referred to as SARST‐V1, was used to examine the eubacterial diversity present in community DNA recovered from the microbiome resident in the ovine rumen. The 190 sequenced clones contained 1055 RSTs and no less than 236 unique phylotypes (based on ≥ 95% sequence identity) that were assigned to eight different eubacterial phyla. Rarefaction and monomolecular curve analyses predicted that the complete RST clone library contains 99% of the 353 unique phylotypes predicted to exist in this microbiome. When compared with ribosomal intergenic spacer analysis (RISA) of the same community DNA sample, as well as a compilation of nine previously published conventional rrs clone libraries prepared from the same type of samples, the RST clone library provided a more comprehensive characterization of the eubacterial diversity present in rumen microbiomes. As such, SARST‐V1 should be a useful tool applicable to comprehensive examination of diversity and composition in microbiomes and offers an affordable, sequence‐based method for diversity analysis.
Preventive effects of glycaemic control on ocular complications of Spontaneously Diabetic Torii rat
Authors: Sasase T. , Ohta T. , Ogawa N. , Miyajima K. , Ito M. , Yamamoto H. , Morinaga H. , Matsushita M. 
Published: October 2005

Aim:  Spontaneously Diabetic Torii (SDT) rat is a new model of non‐obese type 2 diabetes. SDT rats show severe ocular complications such as cataracts, tractional retinal detachment with fibrous proliferation and massive haemorrhaging in the anterior chamber. In the present study, blood glucose levels of SDT rats were controlled in order to examine whether these ocular complications are caused by hyperglycaemia.Methods:  SDT rats were treated with an insulin implant to control blood glucose. To evaluate retinal function, we used electroretinograms (ERG) and measured vascular endothelial growth factor (VEGF) concentrations within the aqueous humour. Finally, we studied retinal flat‐mounts and trypsin digestion to evaluate vascular abnormalities in SDT rats.Results:  Forty‐four‐week‐old SDT rats displayed an increase in VEGF concentrations within the aqueous humour and significant prolongation of the peak latencies in ERG (Σ(OP1–OP4); Sprague–Dawley (SD): 146.2 ± 1.06 ms; SDT: 166.3 ± 2.38 ms; SDT + insulin: 149.2 ± 1.83 ms). Retinal flat‐mounts of SDT rats showed venous dilation and meandering vascular networks. Furthermore, acellular capillaries were observed in the retinal trypsin digestion. Insulin treatment prevented these ocular abnormalities in SDT rats.Conclusions:  These findings indicate that ocular complications of SDT rats are caused by hyperglycaemia. The features of SDT rats indicate their usefulness for the future study of diabetic retinopathy.
Gelatinization temperature of rice explained by polymorphisms in starch synthase
Authors: Waters Daniel L. E. , Henry Robert J. , Reinke Russell F. , Fitzgerald Melissa A. 
Published: October 2005

SummaryThe cooking quality of rice is associated with the starch gelatinization temperature (GT). Rice genotypes with low GT have probably been selected for their cooking quality by humans during domestication. We now report polymorphisms in starch synthase IIa (SSIIa) that explain the variation in rice starch GT. Sequence analysis of the eight exons of SSIIa identified significant polymorphism in only exon 8. These single nucleotide polymorphisms (SNPs) were determined in 70 diverse genotypes of rice. Two SNPs could classify all 70 genotypes into either high GT or low GT types which differed in GT by 8 °C. ‘A’ rather than ‘G’ at base 2412 determined whether a methionine or valine was present at the corresponding amino acid residue in SSIIa, whilst two adjacent SNPs at bases 2543 and 2544 coded for either leucine (GC) or phenylalanine (TT). Rice varieties with high GT starch had a combination of valine and leucine at these residues. In contrast, rice varieties with low GT starch had a combination of either methionine and leucine or valine and phenylalanine at these same residues. At least two distinct polymorphisms have apparently been selected for their desirable cooking qualities in the domestication of rice.