bluuebunny/crossref_metadata_2025_split huggingface dataset:
Nutrient resorption from senescing leaves in twoStipaspecies native to central Argentina
Authors: Distel R. A. , Moretto A. S. , Didoné N. G. 
Published: December 2004

Abstract Nutrient resorption from senescing leaves enables plants to conserve and reuse nutrients. As such, it could be expected that plant species adapted to infertile soils have a higher nutrient resorption efficiency (percentage reduction of nutrients between green and senesced leaves) and/or higher nutrient resorption proficiency (absolute reduction of nutrients in senesced leaves) than those adapted to fertile soils. Our objective was to compare nitrogen (N) and phosphorous (P) resorption of two congener grasses that successfully occupy uplands of relatively low fertility (Stipa gynerioides) or lowlands of relatively high fertility (Stipa brachychaeta) in natural grasslands of central Argentina. The twoStipaspecies did not differ in N and P resorption efficiency, butS. gynerioideshad a higher N and P resorption proficiency thanS. brachychaeta. As a consequence, leaf‐level N and P use efficiency were higher in the species adapted to low fertility conditions than in the species adapted to high fertility conditions. The higher nutrient resorption proficiency ofS. gynerioideswas also associated with relatively low leaf‐litter decomposition and nutrient release rates found in a previous study.
Comparison of the nutrient ecology of coastal Banksia grandis elfinwood (windswept shrub‐like form) and low trees, Cape Leeuwin‐Naturaliste National Park, Western Australia
Authors: BARRICK KENNETH A. 
Published: December 2004

Abstract  Trees growing along windy coasts often have canopies that are greatly reduced in size by the sculpting effects of wind and salt spray. Trees with environmentally reduced stature are called elfinwood (windswept shrub‐form or krummholz) and are ecologically important because they represent outposts growing at the limit of tree success. The purpose of this study was to assess if Banksia grandis elfinwood growing at Cape Leeuwin had a different nutrient status than normal low‐form (LF) trees growing nearby, and if nutrient deficiencies, toxicities and/or imbalances were among the limiting factors imposed on elfinwood. The concentrations of N, P, K, Ca, Mg, Na, Cl–, Fe, Mn, Zn, Cu, Mo and B were analysed for mature green foliage, immature foliage, foliage litter, flowers and soil. When the elfinwood and LF trees were compared, the foliar nutrient status was generally similar, except that elfinwood foliage had significantly higher mean concentrations of N, Zn and Cu, while LF trees had higher Fe and Mn contents. Many nutrients were conserved before leaves were shed in both elfinwood and LF trees, including N, P, K, Na, Cl–, Mn and Cu (LF trees also conserved Ca and Mg). However, elfinwood and LF tree‐litter contained significantly higher Fe concentrations than green foliage (elfinwood litter also had higher levels of Mg and B). It is tempting to suggest that the translocation of Fe into leaves before they were shed is a regulation mechanism to prevent Fe toxicity, or imbalance in the Fe : Mn ratio. Proteoid roots strongly acidify the soil to mobilize P, which also chemically reduces Fe+3 to plant‐available Fe+2. The increased supply of Fe+2 in the rhizosphere, caused by the action of proteoid roots, might tend to defeat self‐regulation of Fe uptake. It is possible that excess Fe accumulation in the plant might be regulated, in part, by exporting Fe into the leaves before they are shed. The nutrient status of B. grandis elfinwood is compared with mountain elfinwood of North America. The extreme habitat of coastal elfinwood provides many theoretical pathways for nutrient limitation, but B. grandis elfinwood at Cape Leeuwin does not appear to be nutrient deficient.
Early development of metanephridia in the caudal budding zone of a clitellate annelid, Dero digitata (Naidida): an electron‐microscopical study
Authors: Bunke Dieter 
Published: December 2004

AbstractUltrastructural analysis has revealed that metanephridia in Dero digitata arise from three nephroblast cells in the frontal epithelium of a septum suggesting its mesodermal origin. Each cell has a fixed developmental destination, one nephroblast cell produces the entire canal part and two cells give rise to the nephrostome. The nephroblast cell nearest to the body wall enlarges and proliferates a first set of canal cells, then one of the two proximally adjacent nephroblast cells differentiates into the envelope of the nephrostome generating the marginal cilia of the opening (mantle cell) and the second one transforms into the anteriormost cell of the funnel, producing a flame of cilia that beats into the canal lumen (flame cell). Thereafter, new canal cells appear, mainly by mitosis of the first cell, enlarging the body of the nephridium whose further differentiation was not analysed. Comparison with other clitellate species suggests a mantle cell (or some marginal cells) and a flame cell (or a central cell) to be special characters of the metanephridium in the stem species of the Clitellata and that, compared to many polychaete species, its early development assumes a special course by a precocious determination and arrangement of nephroblast cells, which, in both groups, probably originate from an identical mesodermal stem cell. Results further indicate that the nonclitellate Aeolosomatidae, by virtue of corresponding nephrostomata, are possibly closer related to the Clitellata.
Follicular epithelium, theca and egg envelope formation in Serrasalmus spilopleura (Teleostei, Characiformes, Characidae)
Authors: Quagio‐Grassiotto I. , Guimarães A. C. D. 
Published: December 2004

AbstractThe follicular epithelium and theca of oocytes in Serrasalmus spilopleura differentiates during the initial primary growth phase. The follicular cells are squamous and the thecal cells are disposed in two layers. During the secondary growth phase, follicular cells become cuboidal, acquire characteristics typical of protein‐ or glycoprotein‐producing cells, and show dilated intercellular spaces. Formation of the egg envelope in S. spilopleura begins in the previtellogenic oocytes as a layer of amorphous electron‐dense material is laid down on the oolemma. During vitellogenesis, another layer of electron‐dense material appears beneath the first layer. Also during this phase, a layer of amorphous, less electron‐dense material is formed adjacent to the follicular epithelium. The secondary egg envelope appears at the postvitellogenic phase and is composed of a filamentous and undulant material. The morphology of the egg envelopes in S. spilopleura reflects not only its oviparous nature but also the fact that its eggs are adhesive.
Cauda epididymal spermatozoa of the rufous hare wallaby, Lagorchestes hirsutus (Metatheria, Mammalia) imaged by electron and confocal microscopy
Authors: Johnston S. D. , Daddow L. , Carrick F. N. , Jamieson B. , Smith L. 
Published: December 2004

AbstractThe ultrastructure of mature Lagorchestes hirsutus spermatozoa is described for the first time, revealing unusual aspects of sperm structure in macropodid species. The sperm head is ovoid rather than cuneiform, lacks a ventral nuclear groove and has an acrosomal distribution over approximately 85–90% of its dorsal surface. Immediately adjacent to the nuclear membrane the peripheral nucleoplasm in most spermatozoa form an irregular series of distinctive evaginations previously not described in the spermatozoa of any other marsupial. The midpiece is extremely thickened and short, containing no helical network or peripheral plasma membrane specializations. Axonemal structure is unspecialized with no connecting lamellae; dense outer fibres are closely adherent to axonemal doublets. The sperm morphology of this species is highly aberrant in comparison to other macropod taxa and supports the retention of Lagorchestes as a distinctive genus. In light of this new information, skeletal and serological data should be re‐evaluated to determine the true taxonomic and phylogenetic position of this species.
Effect of long‐term consumption of probiotic milk on infections in children attending day care centres: double blind, randomised trial.
Authors: Reading Richard 
Published: December 2004

Objective To examine whether long‐term consumption of a probiotic milk could reduce gastrointestinal and respiratory infections in children in day care centres.Design Randomised, double blind, placebo controlled study over 7 months.Setting Eighteen day care centres in Helsinki, Finland.Participants A total of 571 healthy children aged 1–6 years: 282 [mean (SD) age 4.6 (1.5) years] in the intervention group and 289 [mean (SD) age 4.4 (1.5) years] in the control group.Intervention Milk with or without Lactobacillus GG. Average daily consumption of milk in both groups was 260 mL.Main outcome measures Number of days with respiratory and gastrointestinal symptoms, absences from day care because of illness, respiratory tract infections diagnosed by a doctor, and course of antibiotics.ResultsChildren in the Lactobacillus group had fewer days of absence from day care because of illness [4.9 (95% confidence interval 4.4–5.5) versus 5.8 (5.3–6.4) days, 16% difference, p = 0.03; age adjusted 5.1 (4.6–5.6) versus 5.7 (5.2–6.3) days, 11% difference, p = 0.09]. There was also a relative reduction of 17% in the number of children suffering from respiratory infections with complications and lower respiratory tract infections [unadjusted absolute percentage reduction 8.6 (17.2–0.1), p = 0.05; age adjusted odds ratio 0.75 (0.52–1.09), p = 0.13] and a 19% relative reduction in antibiotic treatments for respiratory infection [unadjusted absolute percentage reduction 9.6 (18.2–1.0), p = 0.03; adjusted odds ratio 0.72 (0.50–1.03), p = 0.08] in the Lactobacillus group.ConclusionsLactobacillus GG may reduce respiratory infections and their severity among children in day care. The effects of the probiotic Lactobacillus GG were modest but consistently in the same direction.
Combined Segregation and Linkage Analysis of Fibrinogen Variability in Israeli Families: Evidence for Two Quantitative‐trait Loci, One of Which is Linked to a Functional Variant (−58G > A) in the Promoter of the α‐fibrinogen Gene
Authors: Friedlander Y. , Kark J. D. , Sinnreich R. , Basso F. , Humphries S. E. 
Published: December 2004

SummaryThe association of α‐ and β‐fibrinogen polymorphisms with plasma fibrinogen levels was examined in a sample of 452 family members from 80 Israeli kindreds. The measured genotype analysis indicated that the β‐fibrinogen −455G > A polymorphism was not associated with fibrinogen levels, while the α‐fibrinogen −58G > A locus showed a significant association with fibrinogen levels (χ2= 17.7; df = 3; p < 0.001), with the −58A allele being associated with higher levels. Segregation analysis in this sample suggested a recessive quantitative‐trait locus (QTL) with a major effect that controlled the sex‐ and age‐adjusted fibrinogen levels. Results from a combined segregation/linkage analysis indicated that a single QTL influencing plasma fibrinogen is in gametic equilibrium with the β‐fibrinogen −455G > A and α‐fibrinogen −58G > A polymorphisms. An extended analysis with a two‐QTL model significantly improved the fit of the model (p ≤ 0.001), and gave support for linkage between the fibrinogen QTL and the α‐fibrinogen polymorphism. In vitro analysis with a DNA fragment containing this variant, linked to a reporter gene, showed 2‐fold higher expression of the A allele compared to the G allele in the liver cell line HepG2, both under basal conditions and after stimulation with interleukin 6. These results demonstrate that two QTLs are jointly involved in determining plasma fibrinogen levels in this sample of families, one of which is located close to a functional variant in the α‐fibrinogen locus.
The Human Complement Component C1R Gene: The Exon‐intron Structure and the Molecular Basis of Allelic Diversity
Authors: Nakagawa M. , Yuasa I. , Irizawa Y. , Umetsu K. 
Published: December 2004

SummaryHuman C1r is a component of the complement system, which is a major mediator of innate immunity. In this study we investigated the exon‐intron organization of the human C1R gene, which spans 11 kb from the initiation codon to the stop codon, and is very similar in exon‐intron structure to the C1S gene. Six common and rare alleles, C1R*1, C1R*2, C1R*5, C1R*8, C1R*9, and C1R*13, were characterized by five mutations at amino acid positions 114, 135, 146, 167 and 244, in exons 4, 5 and 7 where the CUB1, EGF and CUB2 domains are encoded, respectively. A comparison with the cDNA of the mouse C1r gene showed that C1R*2is likely to be an ancestral allele. In addition, nine nucleotide substitutions and one length polymorphism were found in introns 2, 3, 4, 8 and 10.
Saturation of the 5q31‐q33 Candidate Region for Coeliac Disease
Authors: Percopo S. , Babron M.‐C. , Whalen M. , De Virgiliis S. , Coto I. , Clerget‐Darpoux F. , Landolfo F. , Greco L. 
Published: December 2004

SummaryThe first genome wide screening performed on Italian affected sib‐pair families (Greco et al. 1998) gave evidence for linkage with coeliac disease in the 5q region. This finding was replicated in a second independent dataset (Greco et al. 2001). Overall, pooling both samples, the highest MLS value (2.92) was found for the most centromeric marker tested, D5S640. In the present study, the 5q31‐q33 region was saturated with 12 new markers around D5S640, in order to verify whether there would be a shift of the MLS position. This study allowed us to support our previous finding of linkage for the region 5q31‐q33, with the most significant MLS value at D5S2014, very close to the marker D5S640. No evidence for interaction between this risk factor and the one in the HLA region was found. Furthermore, many different groups have independently obtained analogous results for this region, confirming the presence of a susceptibility locus in the region 5q31‐q33. This region contains several interesting candidate genes for coeliac disease.
Smith‐Lemli‐Opitz Syndrome and the DHCR7 Gene
Authors: Jira P. E. , Waterham H. R. , Wanders R. J. A. , Smeitink J. A. M. , Sengers R. C. A. , Wevers R. A. 
Published: December 2004

SummarySmith‐Lemli‐Opitz syndrome, a severe developmental disorder associated with multiple congenital anomalies, is caused by a defect of cholesterol biosynthesis. Low cholesterol and high concentrations of its direct precursor, 7‐dehydrocholesterol, in plasma and tissues are the diagnostic biochemical hallmarks of the syndrome. The plasma sterol concentrations correlate with severity and disease outcome. Mutations in the DHCR7 gene lead to deficient activity of 7‐dehydrocholesterol reductase (DHCR7), the final enzyme of the cholesterol biosynthetic pathway. The human DHCR7 gene is localised on chromosome 11q13 and its structure has been characterized. Ninety‐one different mutations in the DHCR7 gene have been published to date. This paper is a review of the clinical, biochemical and molecular genetic aspects.
Qualitative Semi‐Parametric Test for Genetic Associations in Case‐Control Designs Under Structured Populations
Authors: Chen H.‐S. , Zhu X. , Zhao H. , Zhang S. 
Published: December 2004

SummaryRecently, statistical methods have been proposed using genomic markers to control for population stratification in genetic association studies. However, these methods either have unacceptable low power when population stratification becomes strong or cannot control for population stratification well under admixture population models. In this paper, we propose a semiparametric association test to detect genetic association between a candidate marker and a qualitative trait of interest in case‐control designs. The performanceof the test is compared to other existing methods through simulations. The results show that our method gives correct type I error rate both under discrete population models and admixture population models, and our method is robust to the extent of the population stratification. In most of the cases we considered, our method has higher power and, in some cases, substantially higher power than that of existing methods.
Differentiation of Caucasians and Chinese at Bone Mass Candidate Genes: Implication for Ethnic Difference of Bone Mass
Authors: Dvornyk V. , Liu X.‐H. , Shen H. , Lei S.‐F. , Zhao L.‐J. , Huang Q.‐R. , Qin Y.‐J. , Jiang D.‐K. , Long J.‐R. , Zhang Y.‐Y. , Gong G. , Recker R. R. , Deng H.‐W. 
Published: December 2004

SummaryBone mineral density (BMD) is an important risk factor for osteoporosis and has strong genetic determination. While average BMD differs among major ethnic groups, several important candidate genes have been shown to underlie BMD variation within populations of the same ethnicity. To investigate whether important candidate genes may contribute to ethnic differences in BMD, we studied the degree of genetic differentiation among several important candidate genes between two major ethnic groups: Caucasians and Chinese. The genetic variability of these two populations (1131 randomly selected individuals) was studied at six restriction sites exhibiting polymorphisms of five important candidate genes for BMD: the BsaHI polymorphism of the calcium‐sensing receptor (CASR) gene, the SacI polymorphism of the α2HS‐glycoprotein (AHSG) gene, the PvuII and XbaI polymorphisms of the estrogen receptor α (ESR1) gene, the ApaI polymorphism of the vitamin D receptor (VDR) gene, and the BstBI polymorphism of the parathyroid hormone (PTH) gene. The two ethnic groups showed significant allelic and genotypic differentiation of all the polymorphisms studied. The mean FST was 0.103, which significantly differed from zero (P < 0.01). The Chinese population had lower mean heterozygosity (0.331) than the Caucasian one (0.444); the CASR‐BsaHI and PTH‐BstBI polymorphisms contributed most significantly to this difference. Analysis of the intra‐ and inter‐population variability suggests that various types of natural selection may affect the observed patterns of variation at some loci. If some of the candidate genes we studied indeed underlie variation in BMD, their population differentiation revealed here between ethnic groups may contribute to understanding ethnic difference in BMD.
CpG Islands in Human X‐Inactivation
Authors: Ke X. , Collins A. 
Published: December 2004

SummarySequence comparison analyses have been carried out for 19 genes escaping X‐inactivation versus 73 genes subject to X‐inactivation, and 100 randomly chosen X chromosome genes versus 100 randomly chosen autosomal genes. The coding sequence of the genes and their upstream and downstream flanking sequences were investigated using a series of windows (1 kb, 2 kb, 5 kb, 10 kb and 100 kb). No significant difference in number of LINE‐L1 elements was observed in genes escaping X‐inactivation compared to genes subject to X‐inactivation. This result, therefore, does not support the suggestion that lack of LINE repeat elements is a key factor for genes escaping X‐inactivation. However, significantly reduced numbers of CpG islands and SINE MIR elements were found to be associated with genes escaping X‐inactivation. Compared to genes known to be inactivated, genes escaping X‐inactivation were observed to have fewer CpG islands, particularly within the 2 kb upstream flanking sequence close to the coding region. The results suggest that CpG islands may play a role in the process of X‐inactivation by providing sufficient DNA methylation targets for the maintenance of X‐inactivation. Lack of CpG islands may be a major reason for genes escaping X‐inactivation regulation.
Evaluating Innovations in Maternity Care: Methodological Approaches to a Baseline Postal Survey
Authors: Yelland Jane , Brown Stephanie , Krastev Ann 
Published: December 2004

Abstract: Background: A network of four public maternity hospitals in Melbourne, Australia, has implemented a range of initiatives aimed at improving maternity care. Comprehensive evaluation aims to determine whether or not the maternity service enhancement strategies have led to improvements in women's views and experiences of care. This paper discusses the baseline survey study design and methodological issues associated with the recruitment and reminder processes.Method: All women who gave birth over a 14‐week period in 1999 at one of the four maternity units, except those who had a stillbirth or neonatal death, were invited to participate in the baseline postal survey. Questionnaires were sent to women at 3 months postpartum. A system of written and telephone reminders was instituted.Results: The overall response fraction to the baseline survey was 65.2 percent (1256/1922). The sample was representative in terms of maternal age, method of birth, and infant birthweight. Women born overseas of non‐English speaking background, single women, and women having their second or subsequent baby were underrepresented.Conclusions: The pleasing response fraction in part may be attributed to the method of recruitment and the reminder processes. Rigorous and careful approaches to methodology enhance study integrity and provide context to the interpretation of study findings. (BIRTH 30:3 September 2003)
Methods for testing familial aggregation of diseases in population‐based samples: application to hodgkin lymphoma in swedish registry data
Authors: Pfeiffer R. M. , Goldin L. R. , Chatterjee N. , Daugherty S. , Hemminki K. , Pee D. , X L. I. , Gail M. H. 
Published: December 2004

SummaryWe use data on lymphoma in families of Hodgkin lymphoma (HL) cases from the Swedish Family Cancer Database (Hemminki et al. 2001) to illustrate survival methods for detecting familial aggregation in first degree relatives of case probands compared to first degree relatives of control probands, from registries that permit sampling of all cases. Because more than one case may occur in a given family, the first degree relatives of case probands are not necessarily independent, and we present procedures that allow for such dependence. A bootstrap procedure also accommodates matching of case and control probands by resampling the matching clusters, defined as the combined set of all first degree relatives of the matched case and control probands. Regarding families as independent sampling units leads to inferences based on “sandwich variance estimators” and accounts for dependencies from having more than one proband in a family, but not for matching. We compare these methods in analysis of familial aggregation of HL and also present simulations to compare survival analyses with analyses of binary outcome data.