bluuebunny/crossref_metadata_2025 huggingface dataset:
PTPN22 Trp620 Explains the Association of Chromosome 1p13 With Type 1 Diabetes and Shows a Statistical Interaction With HLA Class II Genotypes
Authors: Smyth Deborah J. , Cooper Jason D. , Howson Joanna M.M. , Walker Neil M. , Plagnol Vincent , Stevens Helen , Clayton David G. , Todd John A.
Published: February 2008

OBJECTIVE—The disease association of the common 1858C>T Arg620Trp (rs2476601) nonsynonymous single nucleotide polymorphism (SNP) of protein tyrosine phosphatase; nonreceptor type 22 (PTPN22) on chromosome 1p13 has been confirmed in type 1 diabetes and also in other autoimmune diseases, including rheumatoid arthritis and Graves’ disease. Some studies have reported additional associated SNPs independent of rs2476601/Trp620, suggesting that it may not be the sole causal variant in the region and that the relative risk of rs2476601/Trp620 is greater in lower risk by HLA class II genotypes than in the highest risk class II risk category.

RESEARCH DESIGN AND METHODS—We resequenced PTPN22 and used these and other data to provide >150 SNPs to evaluate the association of the PTPN22 gene and its flanking chromosome region with type 1 diabetes in a minimum of 2,000 case subjects and 2,400 control subjects.

RESULTS—Due to linkage disequilibrium, we were unable to distinguish between rs2476601/Trp620 (P = 2.11 ×10−87) and rs6679677 (P = 3.21 ×10−87), an intergenic SNP between the genes putative homeodomain transcription factor 1 and round spermatid basic protein 1. None of the previously reported disease-associated SNPs proved to be independent of rs2476601/Trp620. We did not detect any interaction with age at diagnosis or sex. However, we found that rs2476601/Trp620 has a higher relative risk in type 1 diabetic case subjects carrying lower risk HLA class II genotypes than in those carrying higher risk ones (P = 1.36 × 10−4 in a test of interaction).

CONCLUSIONS—In our datasets, there was no evidence for allelic heterogeneity at the PTPN22 locus in type 1 diabetes, indicating that the SNP rs2476601/Trp620 remains the best candidate in this chromosome region in European populations. The heterogeneity of rs2476601/Trp620 disease risk by HLA class II genotype is consistent with previous studies, and the joint effect of the two loci is still greater in the high-risk group.
Changes in Gut Microbiota Control Metabolic Endotoxemia-Induced Inflammation in High-Fat Diet–Induced Obesity and Diabetes in Mice
Authors: Cani Patrice D. , Bibiloni Rodrigo , Knauf Claude , Waget Aurélie , Neyrinck Audrey M. , Delzenne Nathalie M. , Burcelin Rémy
Published: February 2008

OBJECTIVE—Diabetes and obesity are characterized by a low-grade inflammation whose molecular origin is unknown. We previously determined, first, that metabolic endotoxemia controls the inflammatory tone, body weight gain, and diabetes, and second, that high-fat feeding modulates gut microbiota and the plasma concentration of lipopolysaccharide (LPS), i.e., metabolic endotoxemia. Therefore, it remained to demonstrate whether changes in gut microbiota control the occurrence of metabolic diseases.

RESEARCH DESIGN AND METHODS—We changed gut microbiota by means of antibiotic treatment to demonstrate, first, that changes in gut microbiota could be responsible for the control of metabolic endotoxemia, the low-grade inflammation, obesity, and type 2 diabetes and, second, to provide some mechanisms responsible for such effect.

RESULTS—We found that changes of gut microbiota induced by an antibiotic treatment reduced metabolic endotoxemia and the cecal content of LPS in both high-fat–fed and ob/ob mice. This effect was correlated with reduced glucose intolerance, body weight gain, fat mass development, lower inflammation, oxidative stress, and macrophage infiltration marker mRNA expression in visceral adipose tissue. Importantly, high-fat feeding strongly increased intestinal permeability and reduced the expression of genes coding for proteins of the tight junctions. Furthermore, the absence of CD14 in ob/ob CD14−/− mutant mice mimicked the metabolic and inflammatory effects of antibiotics.

CONCLUSIONS—This new finding demonstrates that changes in gut microbiota controls metabolic endotoxemia, inflammation, and associated disorders by a mechanism that could increase intestinal permeability. It would thus be useful to develop strategies for changing gut microbiota to control, intestinal permeability, metabolic endotoxemia, and associated disorders.
Quantifying the Excess Risk of Type 2 Diabetes by Body Habitus Measurements Among Australian Aborigines Living in Remote Areas
Authors: Kondalsamy-Chennakesavan Srinivas , Hoy Wendy E. , Wang Zhiqiang , Shaw Jonathan
Published: February 2008

OBJECTIVE—To quantify the risk for type 2 diabetes by body habitus measurements among remote-living Australian Aborigines relative to that measured in the general Australian population (as characterized by the Australian Diabetes, Obesity and Lifestyle [AusDiab] study).

RESEARCH DESIGN AND METHODS—Anthropometric measurements and diabetes status were assessed by standard procedures among Aborigines (n = 1,456) and Australians aged ≥25 years (n = 11,247). Age-adjusted odds ratios (ORs) for diabetes among Aborigines relative to AusDiab participants were calculated by commonly used categories of body size measurements.

RESULTS—The OR (95% CI) values for diabetes among normal, overweight, and obese (by waist) Aboriginal women relative to AusDiab women were 2.6 (0.6–11.5), 13.1 (6.7–25.7), and 6.1 (4.6–8.0), respectively, and for Aboriginal men relative to AusDiab men, they were 7.6 (4.6–12.5), 7.6 (4.3–13.4), and 5.2 (3.4–8.0), respectively. Rates of diabetes were also excessive in Aborigines for each standard category of BMI.

CONCLUSIONS—Higher rates of diabetes, even at normal and lower body habitus measurements, among Aborigines suggest that strategies for prevention should expand beyond exclusive focus on diet and weight management.
Is a Failure to Recognize an Increase in Food Intake a Key to Understanding Insulin-Induced Weight Gain?
Authors: Ryan Miriam , Livingstone M. Barbara E. , Ducluzeau Pierre-Henri , Sallé Agnès , Genaitay Manon , Ritz Patrick
Published: February 2008

The present study aimed to assess the contribution of energy intake to positive energy balance and weight gain with insulin therapy. Changes in energy intake (self-report and weighed food intake), dietary behavior (auto-questionnaires), resting energy expenditure (REE) (indirect calorimetry), physical activity (accelerometry), and glucosuria were monitored over the first 6 months of insulin therapy in 46 diabetic adults. No change in REE, activity, or glucosuria could explain weight gain in the type 1 (4.1 ± 0.6 kg, P < 0.0001) or type 2 (1.8 ± 0.8 kg, P = 0.02) diabetic groups. An increase in energy intake provides the most likely explanation for weight gain with insulin. However, it is not being recognized because of significant underestimation of self-reported food intake, which appears to be associated with increased dietary restraint.
Objectively Measured Time Spent Sedentary Is Associated With Insulin Resistance Independent of Overall and Central Body Fat in 9- to 10-Year-Old Portuguese Children
Authors: Sardinha Luis B. , Andersen Lars Bo , Anderssen Sigmund A. , Quitério Ana L. , Ornelas Rui , Froberg Karsten , Riddoch Chris J. , Ekelund Ulf
Published: February 2008

OBJECTIVE—We examined the independent relationships between objectively measured physical activity and insulin resistance in Portuguese children.

RESEARCH DESIGN AND METHODS—This is a school-based, cross-sectional study in 147 randomly selected girls (aged 9.8 ± 0.3 years; 27.8 ± 9.3% body fat) and 161 boys (aged 9.8 ± 0.3 years; 22.0 ± 9.2% body fat). Physical activity was assessed by the Actigraph accelerometer for 4 days and summarized as time spent sedentary (accelerometer counts <500/min), in light-intensity (accelerometer counts 500–2,000/min), and in moderate- and vigorous-intensity activity (accelerometer counts >2,001/min). We measured total and central fat mass by dual-energy X-ray absorptiometry. Insulin resistance was expressed as the homeostasis model assessment score.

RESULTS—Time (min/day) spent sedentary was significantly and positively associated with insulin resistance (β-coefficient = 0.001 [95% CI 0.0002–0.002]; P = 0.013). Time spent in moderate- and vigorous-intensity physical activity (−0.002 [−0.003 to −0.001]; P = 0.0009) and overall physical activity (−0.001 [−0.008 to 0.003]; P < 0.0001) were significantly and inversely associated with insulin resistance. All associations remained statistically significant, although they were attenuated after further adjustments for sex, birth weight, sexual maturity, and total or central fat mass (P < 0.03).

CONCLUSIONS—Physical activity is associated with insulin resistance independent of total and central fat mass in children. Our results emphasize the importance of decreasing sedentary behavior and increasing time spent in moderate- and vigorous-intensity activity in children, which may have beneficial effects on metabolic risk factors regardless of the degree of adiposity.
Time to Insulin Initiation Cannot Be Used in Defining Latent Autoimmune Diabetes in Adults
Authors: Brophy Sinead , Yderstræde Knud , Mauricio Didac , Hunter Stephen , Hawa Mohammed , Pozzilli Paolo , Schernthaner Guntram , Schoot Nanette , Buzzetti Raffaella , Davies Helen , Leslie David , Williams Rhys ,   on behalf of the Action LADA Group
Published: February 2008

OBJECTIVE—Latent autoimmune diabetes in adults is type 1 diabetes presenting as non–insulin dependent diabetes. One feature of the selection criteria is time independent of insulin treatment. We examine the validity of this criterion.

RESEARCH DESIGN AND METHODS—Patients were recruited in nine European centers, and clinicians reported on criteria for initiating insulin. All patients were tested for GAD antibodies (GADAs) in a central laboratory. We examined time to insulin treatment for GADA-positive patients in six participating centers.

RESULTS—There was intercenter variation in the criteria used to initiate insulin. Median time to insulin was 16.15 months (interqartile range 6.7–25.5) in centers with GADA testing compared with 45.6 months (29.5–61.8) in centers without routine GADA testing (P < 0.002).

CONCLUSION—Time to insulin should not be used to define patients with LADA because it is dependent on local clinical judgment and the use of laboratory tests for GADA.
Breast-Feeding and Type 2 Diabetes in the Youth of Three Ethnic Groups
Authors: Mayer-Davis Elizabeth J. , Dabelea Dana , Lamichhane Archana Pande , D'Agostino Ralph B. , Liese Angela D. , Thomas Joan , McKeown Robert E. , Hamman Richard F.
Published: February 2008

OBJECTIVE—To evaluate the hypothesis that breast-feeding is associated with reduced type 2 diabetes among African-American, Hispanic, and non-Hispanic white youth, mediated in part by current weight status.

RESEARCH DESIGN AND METHODS—The SEARCH Case-Control Study, an ancillary study to SEARCH for Diabetes in Youth, was conducted in two of six SEARCH clinical sites. Eighty youth with type 2 diabetes aged 10–21 years were included. Nondiabetic control participants were recruited from primary care provider offices (n = 167). Breast-feeding information was recalled by biological mothers.

RESULTS—Prevalence (%) of breast-feeding (any duration) was lower among youth with type 2 diabetes than among control subjects (19.5 vs. 27.1 for African Americans, 50.0 vs. 83.8 for Hispanics, and 39.1 vs. 77.6 for non-Hispanic whites). The overall crude odds ratio for the association of breast-feeding (ever versus never) and type 2 diabetes was 0.26 (95% CI 0.15–0.46). Results were similar by race/ethnic group (P value for interaction = 0.17). The odds ratio for the association after adjusting for 12 potential confounders was 0.43 (0.19–0.99). When current BMI z-score was added to the model, the odds ratio was attenuated (0.82 [0.30–2.30]), suggesting possible mediation through current childhood weight status. Analyses that incorporated duration of breast-feeding, adjusted for potential confounders, provided evidence for dose response (test for trend, P value <0.0001), even after inclusion of BMI z-score.

CONCLUSIONS—Breast-feeding appears to be protective against development of type 2 diabetes in youth, mediated in part by current weight status in childhood.
Effect of Aging on Glucose Homeostasis
Authors: Szoke Ervin , Shrayyef Muhammad Z. , Messing Susan , Woerle Hans J. , van Haeften Timon W. , Meyer Christian , Mitrakou Asimina , Pimenta Walkyria , Gerich John E.
Published: February 2008

OBJECTIVE—To examine the effect of aging on insulin secretion (first- and second-phase insulin release) and insulin sensitivity in people with normal glucose tolerance (NGT) or impaired glucose tolerance (IGT).

RESEARCH DESIGN AND METHODS—First- and second-phase insulin secretion and insulin sensitivity were assessed in hyperglycemic clamp experiments in 266 individuals with NGT and 130 individuals with IGT, ranging in age from ∼20 to ∼70 years. Changes in β-cell function were compared using the disposition index to adjust for differences in insulin sensitivity.

RESULTS—As expected, both phases of insulin release and insulin sensitivity were reduced in individuals with IGT (all P < 0.01). Insulin sensitivity was not independently correlated with age in either group. In people with NGT, the disposition index for first- and second-phase insulin release decreased similarly at a rate of ∼0.7% per year. In people with IGT, the disposition indexes for first- and second-phase insulin release decreased at greater rates (∼2.2 and 1.4% per year, P = 0.002 and 0.009, respectively, vs. NGT), with the decrease in first phase being greater than that of second phase (P = 0.025).

CONCLUSIONS—Insulin secretion (both first and second phase) normally decreases at a rate of ∼0.7% per year with aging; this decrease in β-cell function is accelerated about two-fold in people with impaired glucose tolerance—first phase to a greater extent than second phase. Finally, aging per se has no effect on insulin sensitivity independent of changes in body composition.
Gene flow and fine‐scale genetic structure in a wind‐pollinated tree species, Quercus lobata (Fagaceaee)
Authors: Dutech Cyril , Sork Victoria L. , Irwin Andrew J. , Smouse Peter E. , Davis Frank W.
Published: February 2008

California Valley oak (Quercus lobata), one of the state's most distinctive oak species, has experienced serious demographic attrition since the 19th century, due to human activities. Recent estimates of pollen dispersal suggest a small reproductive neighborhood. Whether small neighborhood size is a recent phenomenon, a consequence of reduced gene flow caused by demographic changes, or whether it has been historically restricted, remains unclear. To examine this question, we have characterized the spatial genetic structure of N = 191 Q. lobata individuals, spread over an area of 230 ha, using eight microsatellite loci. The observed autocorrelogram suggests an historical standard deviation of gene flow distance of about 350 m per generation, higher than contemporary pollen dispersal estimates. To determine whether our estimates were affected by strong prevailing winds from the west–northwest, we developed and utilized a novel anisotropic autocorrelation analysis. We detected no more than a hint of anisotropy, and we concluded that adult spatial structure is indicative of strong historical signature of “isolation by distance.” This historical estimate provides a useful reference value against which to gauge the future gene flow consequences of ongoing anthropogenic disturbance.
Dating the Dipsacales: comparing models, genes, and evolutionary implications
Authors: Bell Charles D. , Donoghue Michael J.
Published: February 2008

Dipsacales is an asterid angiosperm clade of ca. 1100 species, with most of its lineages occupying temperate regions of the Northern Hemisphere. A recent phylogenetic analysis based on 7593 nucleotides of chloroplast DNA recovered a well‐resolved and strongly supported phylogenetic hypothesis, which we use here to estimate divergence times within the group. A molecular clock is strongly rejected, regardless of data partition. We used recently proposed methods that relax the assumption of rate constancy among lineages (local clocks, nonparametric rate smoothing, penalized likelihood, and Bayesian relaxed clock) to estimate the ages of major lineages. Age estimates for Dipsacales varied widely among markers and codon positions, and depended on the fossils used for calibration and method of analysis. Some methods yielded dates for the Dipsacales diversification that appear to be too old (prior to the presumed 125 my [million years] age of eudicots), and others suggested ages that are too young based on well‐documented Dipsacales fossils. Concordant penalized likelihood and Bayesian studies imply that Dipsacales originated in the Cretaceous, as did its two major lineages, Adoxaceae and Caprifoliaceae. However, diversification of crown Adoxaceae and Caprifoliaceae mainly occurred in the Tertiary, with the origin of major lineages within these clades mainly occurring during the Eocene. Another round of diversification appears to have occurred in the Miocene. Several radiations, such as Valerianaceae in South America and Dipsacaceae around the Mediterranean, are even more recent. This study demonstrates the wide range of divergence times that can be obtained using different methods and data sets, and cautions against reliance on age estimates based on only a single gene or methodology. Despite this variance, significant conclusions can be made about the timing of Dipsacales evolution.
Effects of pollination by bats on the mating system of Ceiba pentandra (Bombacaceae) populations in two tropical life zones in Costa Rica
Authors: Lobo Jorge A. , Quesada Mauricio , Stoner Kathryn E.
Published: February 2008

The identity and behavior of pollinators are among the main factors that determine the reproductive success and mating system of plants; however, few studies have directly evaluated the relationship between pollinators and the breeding system of the plants they pollinate. It is important to document this relationship because the global decline in pollinators may significantly affect the breeding systems of many animal‐pollinated plants, particularly specialized systems. Ceiba pentandra is a tropical tree that has chiropterophilic flowers and a variable breeding system throughout its distribution, ranging from fully self‐incompatible, to a mixed system with different degrees of selfing. To determine if regional differences in pollinators may result in regional differences in the outcrossing rate of this species, we used systematic observations of pollinator behavior in two tropical life zones and high‐resolution genetic analysis of the breeding system of populations from these two regions using microsatellites. We found a predominantly self‐incompatible system in regions with high pollinator visitation, while in environments with low pollinator visitation rates, C. pentandra changed to a mixed mating system with high levels of self‐pollination.
Seedling expression of cross‐generational plasticity depends on reproductive architecture
Authors: Lundgren Marjorie R. , Sultan Sonia E.
Published: February 2008

Through adaptive cross‐generational plasticity, stressed plants can alter their offspring in specific ways that promote seedling success. As yet, very little is known about the expression of such plasticity, and whether it varies within a plant due to offspring position. The effects of parental light deprivation on distinct reproductive structures were tested in the annual Polygonum hydropiper, which produces both long terminal racemes and inconspicuous axial inflorescences. Inbred replicate parents from four genetic lines were grown in full greenhouse sunlight and simulated shade, and the initial mass, germination rate, and seedling growth traits of their terminal and axial offspring measured under uniform growth chamber conditions. Although parent light environment did not significantly influence seedlings from axial achenes, growth traits of those from terminal achenes were significantly enhanced as a result of parental light deprivation. In shaded conditions where resources are limiting, P. hydropiper plants appear to prioritize terminal achenes through increased provisioning as well as specific growth changes. These results show that the expression of cross‐generational plasticity may vary depending on architectural position of offspring on the maternal plant.
Calceolariaceae: floral development and systematic implications
Authors: Mayr Eva M. , Weber Anton
Published: February 2008

The recent establishment of the new family Calceolariaceae, separated from Scrophulariaceae on the basis of molecular evidence, is complemented here by a scanning electron microscopy study of floral morphology and development of 12 species encompassing all genera (Calceolaria, Jovellana, and Stemotria [* Porodittia]). All species showed a similar pattern of organ initiation. The slightly zygomorphic, four‐merous calyx is the first floral organ series initiated, with the primordia emerging consecutively in a unidirectional (dorso‐ventral) succession. The two entire corolla lips in Calceolaria and Jovellana arise as uniform meristematic ridges (sometimes with a central emargination, especially in Jovellana), kept apart by two lateral stamen primordia. Later the margins of the lips fuse across the backs of the young stamens, giving rise to the short corolla tube (late sympetaly). Stemotria stands out by having three stamens instead of two and a bilobed lower lip, resulting in a trimerous corolla. Similar architecture was found in teratological flowers of Calceolaria. The perianth of Calceolariaceae is shown to be derived from a tetramerous condition, not from pentamery as traditionally believed. This is in agreement with the separation of Calceolariaceae from Scrophulariaceae and with their placement in succession of Oleaceae and Tetrachondraceae in the basal Lamiales. The hitherto puzzling molecular evidence is thus supported by morphological–developmental features of the flower.
Simulated seed predation reveals a variety of germination responses of neotropical rain forest species
Authors: Vallejo‐Marín Mario , Domínguez César A , Dirzo Rodolfo
Published: February 2008

Seed predation, an omnipresent phenomenon in tropical rain forests, is an important determinant of plant recruitment and forest regeneration. Although seed predation destroys large amounts of the seed crop of numerous tropical species, in many cases individual seed damage is only partial. The extent to which partial seed predation affects the recruitment of new individuals in the population depends on the type and magnitude of alteration of the germination behavior of the damaged seeds. We analyzed the germination dynamics of 11 tropical woody species subject to increasing levels of simulated seed predation (0–10% seed mass removal). Germination response to seed damage varied considerably among species but could be grouped into four distinct types: (1) complete inability to germinate under damage ≥1%, (2) no effect on germination dynamics, (3) reduced germination with increasing damage, and (4) reduced final germination but faster germination with increasing damage. We conclude that partial seed predation is often nonlethal and argue that different responses to predation may represent different proximal mechanisms for coping with partial damage, with potential to shape, in the long run, morphological and physiological adaptations in tropical, large‐seeded species.
Ancestral chloroplast polymorphism and historical secondary contact in a broad hybrid zone ofAesculus(Sapindaceae)
Authors: Modliszewski Jennifer L , Thomas David T , Fan Chuanzhu , Crawford Daniel J , de Pamphilis Claude W , Xiang Qiu‐Yun (Jenny)
Published: February 2008

Knowledge regarding the origin and maintenance of hybrid zones is critical for understanding the evolutionary outcomes of natural hybridization. To evaluate the contribution of historical contact vs. long‐distance gene flow in the formation of a broad hybrid zone in central and northern Georgia that involvesAesculus pavia,A. sylvatica, andA. flava, three cpDNA regions (matK,trnD‐trnT, andtrnH‐trnK) were analyzed. The maternal inheritance of cpDNA inAesculuswas confirmed via sequencing ofmatKfrom progeny of controlled crosses. Restriction site analyses identified 21 unique haplotypes among 248 individuals representing 29 populations from parental species and hybrids. Haplotypes were sequenced for all cpDNA regions. Restriction site and sequence data were subjected to phylogeographic and population genetic analyses. Considerable cpDNA variation was detected in the hybrid zone, as well as ancestral cpDNA polymorphism; furthermore, the distribution of haplotypes indicates limited interpopulation gene flow via seeds. The genealogy and structure of genetic variation further support the historical presence ofA. paviain the Piedmont, although they are at present locally extinct. In conjunction with previous allozyme studies, the cpDNA data suggest that the hybrid zone originated through historical local gene flow, yet is maintained by periodic long‐distance pollen dispersal.
Chloroplast DNA variation and geographical structure of the Aristolochia kaempferi group (Aristolochiaceae)
Authors: Watanabe Kana , Kajita Tadashi , Murata Jin
Published: February 2008

The present study documents cpDNA variation in the Aristolochia kaempferi group (Aristolochiaceae), which consists of one Chinese and all Japanese and Taiwanese species of the subgenus Siphisia. In a phylogenetic analysis based on the nucleotide sequences of the matK gene, and the atpB‐rbcL and trnS‐trnG intergenic spacer regions, 38 haplotypes were recognized in the A. kaempferi group and as many as 24 within A. kaempferi. This is the most haplotypes reported for a single species to date. Although six highly significant major clades were identified in the phylogenetic analysis, they were not congruent with previous classifications. This might be attributed to the specific speciation process, such as convergent evolution, incomplete lineage sorting, and/or reticulate evolution. The six major clades had a clear geographical distribution pattern and were significantly associated with geographical distribution of haplotypes in a nested clade analysis and AMOVA. The results allow us to deduce a scenario in which multiple contractions and expansions of the geographical ranges brought about by Quaternary climatic oscillations affected the patterns of genetic diversity. The present geographic patterns of haplotype distribution within the A. kaempferi group can be explained by the last postglacial range expansion from different refugia, and the boundaries may be suture zones.
Variability in leaf optical properties of Mesoamerican trees and the potential for species classification
Authors: Castro‐Esau Karen L. , Sánchez‐Azofeifa G. Arturo , Rivard Benoit , Wright S. Joseph , Quesada Mauricio
Published: February 2008

Leaf traits and physiological performance govern the amount of light reflected from leaves at visible and infrared wavebands. Information on leaf optical properties of tropical trees is scarce. Here, we examine leaf reflectance of Mesoamerican trees for three applications: (1) to compare the magnitude of within‐ and between‐species variability in leaf reflectance, (2) to determine the potential for species identification based on leaf reflectance, and (3) to test the strength of relationships between leaf traits (chlorophyll content, mesophyll attributes, thickness) and leaf spectral reflectance. Within species, shape and amplitude differences between spectra were compared within single leaves, between leaves of a single tree, and between trees. We also investigated the variation in a species' leaf reflectance across sites and seasons. Using forward feature selection and pattern recognition tools, species classification within a single site and season was successful, while classification between sites or seasons was not. The implications of variability in leaf spectral reflectance were considered in light of potential tree crown classifications from remote airborne or satellite‐borne sensors. Species classification is an emerging field with broad applications to tropical biologists and ecologists, including tree demographic studies and habitat diversity assessments.
Variation in the self‐incompatibility response within and among populations of the tropical shrub Witheringia solanacea (Solanaceae)
Authors: Stone Judy L. , Sasuclark Miruna A. , Blomberg Chris P.
Published: February 2008

Breakdown of genetically enforced self‐incompatibility (SI), an extremely common and important evolutionary transition in plants, has conventionally been conceived as a qualitative rather than a quantitative change. We evaluated qualitative and quantitative variation in SI for four populations of Witheringia solanacea in Costa Rica, examining growth of self‐pollen tubes in pollinations of buds and mature flowers. We also measured levels of RNase production in styles to determine whether enzyme production was correlated with differences in self‐rejection. The two small populations contained both self‐compatible (SC) individuals and obligate outcrossers (female or SI). Plants in the two large populations were uniformly SI as revealed by pollen tube growth, although several of these individuals sporadically set seed autogamously. Stylar RNase activity did not differ significantly between bud and mature flowers, but self‐pollen tube growth did differ, suggesting that a gene product in addition to S‐RNase is responsible for developmental onset of SI. Population‐level differences in RNase activity were consistent with differences in the strength of the rejection response in bud pollinations, suggesting that a threshold level of S‐RNase, in combination with other factors, is necessary for SI. Our results support a growing body of evidence that not only qualitative variation in SI, but also quantitative variation may be functionally significant.
Patterns of anomalous floral development in the Asian Passiflora (subgenus Decaloba: supersection Disemma)
Authors: Krosnick Shawn E. , Harris Elizabeth M. , Freudenstein John V.
Published: February 2008

Approximately 22 species of Passiflora are native to the Old World. All of these species are placed in subgenus Decaloba, supersection Disemma. Within Disemma, three species vary in stamen and carpel number (≤ eight stamens and five carpels). The mode of development was determined for two of the anomalous species, P. moluccana var. glaberrima and P. siamica. Ontogenetic patterns were compared to normal development in P. perakensis and P. holosericea. Passiflora siamica develops additional stamens through dédoublement of a single widened stamen primordium, while P. moluccana var. glaberrima exhibits congenital dédoublement where stamens emerge already doubled. Phylogenetic analysis using ITS and the trnL‐F intron and spacer resolve the anomalous species as monophyletic and sister to P. perakensis. This signifies a single loss of genetic regulation in stamen and carpel number within Disemma. Floral whorls were examined across the Passifloraceae, Malesherbiaceae, Turneraceae, and Flacourtiaceae s.l.. Similar doubling in these families suggests that this Eurosid lineage may have a genetic propensity for variability in floral whorl number.
Gas exchange and carbon metabolism in two Prosopis species (Fabaceae) from semiarid habitats: effects of elevated CO2, N supply, and N source
Authors: Causin Humberto F. , Rufty Thomas W. , Reynolds James F.
Published: February 2008

Predicting future plant and ecosystem responses to elevated CO2 also requires an understanding of the role of other factors, especially soil nitrogen. This is particularly challenging for global aridlands where total N and the relative amounts of nitrate and ammonia vary both spatially and seasonally. We measured gas exchange and primary and secondary C metabolites in seedlings of two dominant aridland shrub species (Prosopis flexuosa [S America] and P. glandulosa [N America]) grown at ambient (350 ppm) or elevated (650 ppm) CO2 and nitrogen at two levels (low [0.8 mM] and high [8.0 mM]) and at either 1 : 1 or 3 : 1 nitrate to ammonia. Whereas elevated CO2 increased assimilation rate, water use efficiency, and primary carbon metabolites in both species, these increases were strongly contingent upon nitrogen availability. Elevated CO2 did not increase secondary metabolites (i.e., phenolics). For these important aridland species, the effects of elevated CO2 are strongly influenced by nitrogen availability and to a lesser extent by the relative amounts of nitrate and ammonia supplied, which underscores the importance of both the amount and chemical composition of soil nitrogen in mediating the potential responses of seedling growth and establishment of aridland plants under future CO2‐enriched atmospheres.
The evolutionary history of Sium sensu lato (Apiaceae): dispersal, vicariance, and domestication as inferred from ITS rDNA phylogeny
Authors: Spalik Krzysztof , Downie Stephen R.
Published: February 2008

The biogeographic history of Sium sensu lato (s.l.) (including Sium sensu stricto [s.s.], Afrocarum, and Berula) was inferred using a nuclear rDNA ITS sequence phylogeny and dispersal–vicariance analysis. One hundred accessions were analyzed, including 86 specimens of Sium s.l., representing all taxa throughout their geographical range. The phylogenetic analyses showed that Afrocarum and the African and St. Helena species of Sium were nested within Berula forming the Berula s.l. clade. The remaining species of Sium constituted a weakly supported Sium s.s. clade. The cultivated S. sisarum is closely related to the western Asian S. sisaroideum. The divergence of Sium s.s. from Berula s.l., estimated under the assumption of a molecular clock and using a substitution rate of 0.61% per million years, took place around 10.4 million years ago. Dispersal–vicariance analysis suggested that the biogeographic pattern of this group resulted from simple vicariance and eventual migration to adjacent areas rather than from long‐distance dispersal. The ancestral area of Sium s.l. was probably western Palearctic. The dispersal of Berula to North America occurred ca. 3 million years ago, possibly by island hopping. The migration of S. suave to North America took place ca 0.6 million years ago through Beringia.
Alkaloid polymorphism and ITS sequence variation in the Spiraea japonica complex (Rosaceae) in China: traces of the biological effects of the Himalaya‐Tibet Plateau uplift
Authors: Zhang Zhaoyang , Fan Liming , Yang Junbo , Hao Xiaojiang , Gu Zhijian
Published: February 2008

Spiraea japonica, a diverse, perennial shrubby species complex widespread across E Asia, was a useful model in a first attempt to link specific phylogeny, floristic evolution, and historical environmental changes in E Asia. DNA‐based phylogenetic reconstruction served as a framework to investigate whether the patterns of variation in alkaloids and nrITS from varieties of S. japonica reflect the geological history of China and the uplifting of the Himalaya‐Tibet plateau, the most significant geological event in E Asia since the late Paleocene. The high geographical structure found in the phylogenetic trees was corroborated by the distribution of alkaloids. All populations from E China, with mainly hetisine‐type alkaloids, formed a single clade, sister to a clade of all populations from SW China, with mainly atisine‐type alkaloids. The distribution boundary between the two clades roughly matched the floristic division between the Sino‐Japanese Forest and the Sino‐Himalayan Forest subkingdoms, as well as the environmental division between SW and E China, suggesting a close link between specific phylogeny, floristic evolution, and geographical changes in E Asia. The divergence between lineages at variety and population level within the eastern clade was slightly older than those within the southwestern clade, supporting the hypothesis of a northeast–southwest migration of Spiraea since the Eocene. The uplift of the Himalaya‐Tibet plateau and subsequent increase in geographical complexity in SW China, could facilitate divergence maintenance, thus accelerating the evolutionary rate.
The molecular genetic basis of plant adaptation
Authors: Ehrenreich Ian M. , Purugganan Michael D.
Published: February 2008

How natural selection on adaptive traits is filtered to the genetic level remains largely unknown. Theory and quantitative trait locus (QTL) mapping have provided insights into the number and effect of genes underlying adaptations, but these results have been hampered by questions of applicability to real biological systems and poor resolution, respectively. Advances in molecular technologies have expedited the cloning of adaptive genes through both forward and reverse genetic approaches. Forward approaches start with adaptive traits and attempt to characterize their underlying genetic architectures through linkage disequilibrium mapping, QTL mapping, and other methods. Reverse screens search large sequence data sets for genes that possess the signature of selection. Though both approaches have been successful in identifying adaptive genes in plants, very few, if any, of these adaptations' molecular bases have been fully resolved. The continued isolation of plant adaptive genes will lead to a more comprehensive understanding of natural selection's effect on genes and genomes.
Do sexual dimorphisms in reproductive allocation and new shoot biomass increase with an increase of altitude? A case of the shrub willow Salix reinii (Salicaceae)
Authors: Sakai Akiko , Sasa Ayako , Sakai Satoki
Published: February 2008

Based on the general tendency for females of dioecious plants to pay higher reproductive cost than males, it has been predicted that females should have much more reduced reproductive outputs and diminished vegetative production than males in energy‐limited habitats. Nevertheless, this prediction has rarely been directly investigated. We investigated altitudinal changes in reproductive biomass and shoot production, normalized by plant size, for females and males of a shrub willow, Salix reinii, on Mt. Hakkoda, northeast Japan. Females maintained higher reproductive biomass than males at all altitudes; however, reproductive allocation for both sexes tended to decrease at a similar rate with an increase in altitude. Moreover, females vegetatively produced at the same rate as males at all altitudes. These findings suggest that females have a mechanism to compensate for the extra investment in reproduction irrespective of a changing environment. Shoot production did not change with altitude, suggesting that S. reinii gave priority to vegetative investment at the cost of reproductive output at higher altitudes. Inconsistent with general predictions, females did not respond more sensitively than males to severe environmental conditions in either reproductive allocation or shoot production, despite much higher resource investment in reproduction.
Patterns and development of floral asymmetry in Senna (Leguminosae, Cassiinae)
Authors: Marazzi Brigitte , Endress Peter K.
Published: February 2008

The buzz‐pollinated genus Senna (Leguminosae) is outstanding for including species with monosymmetric flowers and species with diverse asymmetric, enantiomorphic (enantiostylous) flowers. To recognize patterns of homology, we dissected the floral symmetry character complex and explored corolla morphology in 60 Senna species and studied floral development of four enantiomorphic species. The asymmetry morph of a flower is correlated with the direction of spiral calyx aestivation. We recognized five patterns of floral asymmetry, resulting from different combinations of six structural elements: deflection of the carpel, deflection of the median abaxial stamen, deflection or modification in size of one lateral abaxial stamen, and modification in shape and size of one or both lower petals. Prominent corolla asymmetry begins in the earl‐stage bud (unequal development of lower petals). Androecium asymmetry begins either in the midstage bud (unequal development of thecae in median abaxial stamen; twisting of androecium) or at anthesis (stamen deflection). Gynoecium asymmetry begins in early bud (primordium off the median plane, ventral slit laterally oriented) or midstage to late bud (carpel deflection). In enantiostylous flowers, pronouncedly concave and robust petals of both monosymmetric and asymmetric corollas likely function to ricochet and direct pollen flow during buzz pollination. Occurrence of particular combinations of structural elements of floral symmetry in the subclades is shown.
Effects of cell number and cell size on petiole length variation in a stoloniferous herb
Authors: Weijschedé Jelmer , Antonise Koen , de Caluwe Hannie , de Kroon Hans , Huber Heidrun
Published: February 2008

In stoloniferous species, the length of petioles is of pivotal importance because it determines the position of leaf blades within the canopy. From a mechanistic perspective, two developmental processes, cell division and cell elongation, are responsible for the length of a given petiole. This study aimed at quantifying the relative contributions of cell division and cell elongation to genotypic and plastic variation in petiole length of the stoloniferous herb Trifolium repens. Thirty‐four genotypes of T. repens were grown under high light conditions and simulated canopy shade. Cells were counted and their lengths measured on epidermal prints from fully grown petioles of leaves that had been initiated in the experimental light conditions. Cell number was the main trait explaining petiole length differences among genotypes grown under high light, while both cell number and length changed in response to shading. Our study revealed a strong negative correlation between shade‐induced changes in cell number and cell length: genotypes that responded to shading by increasing cell numbers hardly changed in cell length, and vice versa. Our results suggest that genotypic and phenotypic variation in petiole length results from a complex interplay between the developmental processes of cell elongation and cell division.
Resistance and tolerance to herbivory changes with inbreeding and ontogeny in a wild gourd (Cucurbitaceae)
Authors: Du Daolin , Winsor James A. , Smith Matthew , DeNicco Andrew , Stephenson Andrew G.
Published: February 2008

Herbivory is a ubiquitous component of terrestrial communities that reduces plant growth and reproduction. Consequently, a goal of evolutionary ecology is to identify the causes and consequences of variation in herbivory within plant populations. This three‐year study examined the effects of inbreeding on the resistance of wild gourd plants (Cucurbita pepo subsp. texana) to herbivory by cucumber beetles and the impact of the timing of herbivory on reproduction. We grew families of inbred and outbred gourds and recorded beetle damage at three developmental stages, incidence of beetle‐vectored wilt disease, survival, and reproduction. While total beetle damage significantly depressed flower and fruit production, damage until mid‐July did not depress any measure of reproduction, indicating that these gourds are tolerant of moderate levels of herbivory for most of the growing season. However, beetle damage accumulating after mid‐July significantly depressed reproduction, indicating that plants have reduced tolerance during peak reproduction. Early damage, however, did increase the probability of contracting a deadly wilt disease that is vectored by the beetles, suggesting that tolerance and resistance are not alternative defense strategies. Inbreeding significantly reduced resistance to herbivory and, independently of beetle damage, reproductive output. Finally, we found additive genetic variation for both resistance and tolerance that varies with ontogeny.
Genetic variation and phylogeography of Stauracanthus (Fabaceae, Genisteae) from the Iberian Peninsula and northern Morocco assessed by chloroplast microsatellite (cpSSR) markers
Authors: Pardo Cristina , Cubas Paloma , Tahiri Hikmat
Published: February 2008

The tribe Genisteae includes genera of great ecological importance in Mediterranean countries because they are dominant elements of many plant communities. Genetic variation and diversification patterns in Stauracanthus (Genisteae) provide information relevant for the study of the processes of diversification in relation to the environmental history of the western Mediterranean. Nineteen populations of S. boivinii and S. genistoides were assessed by 11 chloroplast microsatellite markers, revealing 44 haplotypes. Both species had different haplotypes and contrasting patterns of karyological, morphological, and genetic variation. In the minimum spanning tree of the haplotypes, AMOVA analysis, and nested clade analysis, S. boivinii had high levels of differentiation and restricted gene flow among populations. Allopatric differentiation occurred between the Moroccan and Iberian populations of S. genistoides, although S. genistoides subsp. spectabilis and subsp. vicentinus had high levels of differentiation among populations (FST), whereas S. genistoides subsp. genistoides had a low FST. Genetic patterns are discussed in relation to the Messinian salinity crisis (MSC): hard conditions drove plants to refuge habitats along the Atlantic coast and higher altitude areas in the Moroccan mountains (S. genistoides subsp. spectabilis and S. boivinii). After the MSC, S. boivinii underwent polyploidization and expansion, whereas S. genistoides expanded and continued diversifying into S. genistoides subspp. genistoides and vicentinus.
Radiation Recall Dermatitis: Case Report and Review of the Literature
Authors: Hird A. E. , Wilson J. , Symons S. , Sinclair E. , Davis M. , Chow E.
Published: February 2008

“Radiation recall”—also called “radiation recall dermatitis”—has been defined as the “recalling” by skin of previous radiation exposure in response to the administration of certain response-inducing drugs. Although the phenomenon is relatively well known in the medical world, an exact cause has not been documented. Here, we report a rare occurrence of the radiation recall phenomenon in a breast cancer patient after palliative radiotherapy for bone, brain, and orbital metastases.