bluuebunny/crossref_metadata_2025 huggingface dataset:
INDUCTION AND REDUCTION OF ANTI‐HERBIVORE DEFENSES IN BROWN AND RED MACROALGAE OFF THE KENYAN COAST1
Authors: Ceh Janja , Molis Markus , Dzeha Thomas M. , Wahl Martin
Published: August 2005

Herbivory is particularly intense in tropical benthic communities, suggesting preference of constitutive, rather than inducible, anti‐herbivory defense. The objective of the study was to examine whether anti‐herbivore defenses in the red algaHypnea pannosaJ. Agardh and the brown algaeSargassum asperifoliumHering and G. Martens ex J. Agardh andCystoseira myrica(S.G. Gmelin) C. Agardh could be induced and subsequently reduced in response to grazing by the amphipodCymadusa filosaSavigny. During a 14‐day treatment phase, algae were exposed to amphipod grazing or were left ungrazed (control). Subsequently, one subset of algae was used in feeding assays, whereas another was cultivated for additional 14 days without consumers (recovery phase). At the end of each phase, bioassays were conducted to detect defensive traits in terms of differences in consumption rates of grazed and control pieces of live algae and agar‐based food containing nonpolar algal extracts. Consumption of grazed liveS. asperifoliumandH. pannosaspecimens was lower than of control algae. Furthermore, nonpolar extracts of grazedS. asperifoliumandC. myricawere less preferred than those from control algae. Defensive responses were exclusively detected after the treatment phase, although strong preference of ungrazedH.pannosaandC.myricaover grazed conspecifics continued throughout the recovery phase. These findings suggest that phenotypic plasticity in anti‐herbivory defense of marine macroalgae 1) might be more common than previously shown, 2) could be switched on and off within 2 weeks, and 3) can be found in nonpolar algal extracts.
EFFECT OF HYPEROXIA ON THE GROWTH AND PHOTOSYNTHESIS OF POLAR SEA ICE MICROALGAE1
Authors: McMinn Andrew , Pankowski Andrew , Delfatti Tom
Published: August 2005

Sea ice algal communities are naturally exposed to very high concentrations of dissolved oxygen, which are likely to lead to increasing stress levels and declines in productivity. To test this hypothesis, cultures of Fragilariopsis cylindrus (Grun?) Hasle, Pseudo‐nitzschia sp., Fragilariopsis curta (Van Heurch), Porosira glacialis (Grunow), and Entomoneis kjellmannii (Cleve) from Antarctic sea ice and Nitzschia frigida from Arctic sea ice were exposed to elevated dissolved oxygen levels, and their growth, maximum quantum yield, relative maximum electron transport rate, and photosynthetic efficiency were measured. At oxygen concentrations equivalent to approximately four times air saturation (89% oxygen), the growth rate and maximum quantum yield were significantly reduced in all taxa. When the oxygen concentration was regularly allowed to drop, the effect on growth and quantum yield was reduced. At lower dissolved oxygen concentrations (52%), the declines in growth and quantum yield were reduced but were still mostly significantly different from the controls (21% oxygen). It is likely that the generation of excess active oxygen radicals in the presence of free oxygen is responsible for most of the decline in growth, maximum quantum yield, relative maximum electron transport rate, and photosynthetic efficiency in all species.
CYANOBACTERIAL ACCLIMATION TO RAPIDLY FLUCTUATING LIGHT IS CONSTRAINED BY INORGANIC CARBON STATUS1
Authors: MacKenzie Tyler D. B. , Campbell Douglas A.
Published: August 2005

Acclimation to rapidly fluctuating light, simulating shallow aquatic habitats, is altered depending on inorganic carbon (Ci) availability. Under steady light of 50 μmol photons·m−2·s−1, the growth rate of Synechococcus elongatus PCC7942 was similar in cells grown in high Ci (4 mM) and low Ci (0.02 mM), with induced carbon concentrating mechanisms compensating for low Ci. Growth under fluctuating light of a 1‐s period averaging 50 μmol photons·m−2·s−1 caused a drop in growth rate of 28%±6% in high Ci cells and 38%±8% in low Ci cells. In high Ci cells under fluctuating light, the PSI/PSII ratio increased, the PSII absorption cross‐section decreased, and the PSII turnover rate increased in a pattern similar to high‐light acclimation. In low Ci cells under fluctuating light, the PSI/PSII ratio decreased, the PSII absorption cross‐section decreased, and the PSII turnover remained slow. Electron transport rate was similar in high and low Ci cells but in both was lower under fluctuating than under steady light. After acclimation to a 1‐s period fluctuating light, electron transport rate decreased under steady or long‐period fluctuating light. We hypothesize that high Ci cells acclimated to exploit the bright phases of the fluctuating light, whereas low Ci cells enlarged their PSII pool to integrate the fluctuating light and dampen the variation of the electron flux into a rate‐restricted Ci pool. Light response curves measured under steady light, widely used to predict photosynthetic rates, do not properly predict photosynthetic rates achieved under fluctuating light, and exploitation of fluctuating light is altered by Ci status.
TREHALOSE SYNTHESIS IN EUGLENA GRACILIS (EUGLENOPHYCEAE) OCCURS THROUGH AN ENZYME COMPLEX1
Authors: Fiol Diego F. , Salerno Graciela L.
Published: August 2005

The aim of this study was to isolate and characterize a trehalose‐synthesizing enzyme from Euglena gracilis Klebs. After purification by anion exchange chromatography, gel filtration, isoelectric focusing, and native electrophoresis, trehalose‐6‐phosphate synthase (TPS, EC 2.4.1.15) and trehalose‐6‐phosphate phosphatase (TPP, EC 3.1.3.12) activities could not be separated. Consequently, a TPS/TPP enzyme complex of about 250 kDa was suggested as responsible for trehalose synthesis in E. gracilis. The TPS activity was shown to be highly specific for glucose‐6‐P, and UDP‐Glc was the preferred glucose donor, but GDP‐Glc and CDP‐Glc could also act as TPS substrates. The TPP activity was highly specific for trehalose‐6‐P. In vitro phosphorylation assays revealed rapid decreases in TPS and TPP activities. These changes corresponded to variations in the elution profile of gel filtration chromatography after the phosphorylation treatment. Taken together, these results suggest that the proposed TPS/TPP complex might be regulated through a protein phosphorylation/dephosphorylation‐mediated mechanism that could affect the association state of the complex. Such a regulatory mechanism might lead to a rapid change in trehalose synthesis in response to variations in environmental conditions.
SPATIOTEMPORAL VARIATION OF THE ABUNDANCE OF CALCAREOUS GREEN MACROALGAE IN THE FLORIDA KEYS: A STUDY OF SYNCHRONY WITHIN A MACROALGAL FUNCTIONAL‐FORM GROUP1
Authors: Collado‐Vides Ligia , Rutten Leanne M. , Fourqurean James W.
Published: August 2005

The abundance of calcareous green algae was recorded quarterly at 28 sites within the Florida Keys National Marine Sanctuary (FKNMS) for a period of 7 years as part of a sea grass monitoring program. To evaluate the validity of using the functional‐form group approach, we designed a sampling method that included the functional‐form group and the component genera. This strategy enabled us to analyze the spatiotemporal patterns in the abundance of calcareous green algae as a group and to describe synchronous behavior among its genera through the application of a nonlinear regression model to both categories of data. Spatial analyses revealed that, in general, all genera displayed long‐term trends of increasing abundance at most sites; however, at some sites the long‐term trends for genera opposed one another. Strong synchrony in the timing of seasonal changes was found among all genera, possibly reflecting similar reproductive and seasonal growth pattern, but the variability in the magnitude of seasonal changes was very high among genera and sites. No spatial patterns were found in long‐term or seasonal changes; the only significant relation detected was for slope, with sites closer to land showing higher values, suggesting that some factors associated with land proximity are affecting this increase. We conclude that the abundances of genera behaved differently from the functional‐form group, indicating that the use of the functional‐form group approach may be unsuitable to detect changes in sea grass community structure in the FKNMS at the existing temporal and spatial scale of the monitoring program.
STRESS‐INDUCED FILAMENT FRAGMENTATION OF CALOTHRIX ELENKINII (CYANOBACTERIA) IS FACILITATED BY DEATH OF HIGH‐FLUORESCENCE CELLS1
Authors: Adamec František , Kaftan David , Nedbal Ladislav
Published: August 2005

Irradiance power and spectral composition as well as nutrient availability strongly influence differentiation of filamentous cyanobacteria. When monitoring the life cycle of Calothrix elenkinii Kossinsk., we found that low nitrogen concentration and growth under green light led to a transient appearance of high‐fluorescence cells that rapidly bleach and disintegrate, thus breaking the parental filament into shorter parts. The dynamics of the process were monitored in a microscope growth chamber by measuring transmission and chl fluorescence of individual cells by a high‐sensitivity camera. Typically, the high‐fluorescence cells appeared near the center of the parental trichome signaled by a rapid 2‐ to 3‐fold rise in their fluorescence emission. By measuring the fluorescence excitation spectra with resolution of individual cells, we showed that the elevated fluorescence emission was largely due to a high absorption by phycoerythrin and energy transfer to chl. Typically, after no more than 20 min, the fluorescence abruptly disappeared with transmission images, indicating loss of pigmentation. The bleaching was a natural process that was not caused by the measuring light. Depending on the mechanical strain, the cell bleaching was followed by breaking of the parental filament. We propose that the high‐fluorescence cells appear as a phase of programmed cell death, allowing the fragmented filaments to escape from unfavorable environmental conditions.
NUTRIENT LIMITATION AND HIGH IRRADIANCE ACCLIMATION REDUCE PAR AND UV‐INDUCED VIABILITY LOSS IN THE ANTARCTIC DIATOM CHAETOCEROS BREVIS (BACILLARIOPHYCEAE)1
Authors: Van De Poll Willem H. , Van Leeuwe Maria A. , Roggeveld Jan , Buma Anita G. J.
Published: August 2005

The effects of high PAR (400–700 nm), UVA (315–400 nm), and UVB (280–315 nm) radiation on viability and photosynthesis were investigated for Chaetoceros brevis Schütt. This Antarctic marine diatom was cultivated under low, medium, and high irradiance and nitrate, phosphate, silicate, and iron limitation before exposure to a simulated surface irradiance (SSI) treatment, with and without UVB radiation. Light‐harvesting and protective pigment composition and PSII parameters were determined before SSI exposure, whereas viability was measured by flow cytometry in combination with a viability stain after the treatment. Recovery of PSII efficiency was measured after 20 h in dim light in a separate experiment. In addition, low and high irradiance acclimated cells were exposed outdoors for 4 h to assess the effects of natural PAR, UVA, and UVB on viability. Low irradiance acclimated cells were particularly sensitive to photo induced viability loss, whereas no viability loss was found after acclimation to high irradiance. Furthermore, nutrient limitation reduced sensitivity to photo induced viability loss, relative to nutrient replete conditions. No additional viability loss was found after UVB exposure. Sunlight exposed cells showed no additional UVB effect on viability, whereas UVA and PAR significantly reduced the viability of low irradiance acclimated cells. Recovery of PSII function was nearly complete in cultures that survived the light treatments. Increased resistance to high irradiance coincided with an increased ratio between protective‐ and light‐harvesting pigments before the SSI treatment, demonstrating the importance of nonphotochemical quenching by diatoxanthin for survival of near‐surface irradiance. We conclude that a sudden transfer to high irradiance can be fatal for low irradiance acclimated C. brevis.
SHORT‐TERM EFFECT OF TEMPERATURE ON THE PHOTOKINETICS OF MICROALGAE FROM THE SURFACE LAYERS OF ANTARCTIC PACK ICE1
Authors: Ralph Peter J. , McMinn Andrew , Ryan Ken G. , Ashworth Chris
Published: August 2005

Microalgae growing within brine channels (85 psu salinity) of the surface ice layers of Antarctic pack ice showed considerable photosynthetic tolerance to the extreme environmental condition. Brine microalgae exposed to temperatures above −5°C and at irradiances up to 350 μmol photons·m−2·s−1 showed no photosynthetic damage or limitations. Photosynthesis was limited (but not photoinhibited) when brine microalgae were exposed to −10°C, provided the irradiance remained under 50 μmol photons·m−2·s−1. The highest level of photosynthetic activity (maximum relative electron transport rate [rETRmax]) in brine microalgae growing within the surface layer of sea ice was at approximately 18 μmol electrons·m−2·s−1, which occurred at −1.8°C. Effective quantum yield of PSII and rETRmax of the halotolerant brine microalgae exhibited a temperature‐dependent pattern, where both parameters were higher at −1.8°C and lower at −10°C. Relative ETRmax at temperatures above −5°C were stable across a wide range of irradiance.
PRESENCE OF SPOROPHYLLS IN FLOATING KELP RAFTS OF MACROCYSTIS SPP. (PHAEOPHYCEAE) ALONG THE CHILEAN PACIFIC COAST1
Authors: Macaya Erasmo C. , Boltaña Sebastián , Hinojosa Iván A. , Macchiavello Juan E. , Valdivia Nelson A. , Vásquez Nelson R. , Buschmann Alejandro H. , Vásquez Julio A. , Alonso Vega J. M. , Thiel Martin
Published: August 2005

Some species of macroalgae continue to live for extended periods of time after detachment and may even maintain reproductive structures, yet very little is known about this process. Here, we describe the presence of sporophylls (with sporogenous tissues) on floating kelp rafts of Macrocystis spp. along the coast of Chile. Surveys were conducted at nine sites (18–50° S) during austral summer 2002, and floating kelp rafts were seen and collected at seven of these nine sites (between 22 and 50° S). Fifteen (26.8%) of the 56 samples had sporophylls, indicating maintenance of sporophylls after detachment. Some of the kelp sporophytes with reproductive blades showed signs of having been afloat for long periods (indicated by the large size of attached stalked barnacles). Additionally, experiments showed that floating kelps released viable zoospores. To understand the reproductive dynamics of floating kelps, we compared these results with information from attached populations of Macrocystis spp. at nearby coastal sites. In general, attached kelp had higher proportions of sporophylls than floating rafts, suggesting that detachment may negatively affect reproductive status. Nevertheless, floating kelps remained functionally reproductive, suggesting that zoospores may be dispersed via floating rafts. Published reports on other macroalgae indicate that some species (Lessoniaceae, Fucaceae, and Sargassaceae) are fertile and probably release zoospores or zygotes while floating or drifting in ocean currents. Because dispersal distances achieved by spores of most macroalgae are relatively short, release of spores from floating algae may be an alternative mechanism of long‐distance dispersal.
IMPACT OF THE INVASIVE SEAWEED SARGASSUM MUTICUM (PHAEOPHYTA) ON AN INTERTIDAL MACROALGAL ASSEMBLAGE1
Authors: Sánchez Íñigo , Fernández Consolación
Published: August 2005

The impact of the invasive seaweed Sargassum muticum (Yendo) Fensholt on a low intertidal macroalgal assemblage was assessed at a semiexposed rocky shore in northern Spain between 2002 and 2004. Sargassum muticum plants were removed from the mature macroalgal assemblage and from those occurring along the successional process of the assemblage. Biomass, richness, diversity, and percentage cover of macroalgae in experimental plots were compared with unmanipulated controls. The effect of S. muticum removal on the macroalgal assemblage more than 2 years after the beginning of the experiment was negligible. Moreover, no differences between treatments were detected in the general patterns of succession. Only significant differences in S. muticum abundance were detected between treatments at the end of the experiment. We suggest that the low abundance of S. muticum at this intertidal level and its pseudoperennial life cycle may limit competition with native macroalgae. However, long‐term removal experiments may be a more indicator of the impact of S. muticum at the upper limit of its vertical distribution.
DIFFERENTIAL LIFE HISTORY PHASE EXPRESSION IN TWO COEXISTING SPECIES OF SCYTOSIPHON (PHAEOPHYCEAE) IN NORTHERN CHILE1
Authors: Camus Carolina , Meynard Andrés P. , Faugeron Sylvain , Kogame Kazuhiro , Correa Juan A.
Published: August 2005

The identity of two phaeophycean taxa that monopolized the middle‐lower rocky intertidal zone of a coastal area chronically exposed to copper mine wastes in northern Chile was unraveled. One of them was preliminarily identified as the gametophytic stage of Scytosiphon lomentaria (Lyngbye) Link. The other, a dark crust, resembled the alternate stage of some Scytosiphon species. Comparative analysis of morphology, life history, and DNA sequences strongly suggests that crusts corresponded to sporophytic S. tenellus Kogame and confirm that erect thalli belonged to S. lomentaria. A clear segregation of erect and crustose thalli was found using internal transcribed spacer region 1 and RUBISCO spacer sequences. Furthermore, whereas crusts always grouped with S. tenellus, erect thalli always grouped with S. lomentaria. Life history studies failed to connect the two entities. First, field‐collected S. tenellus produced progeny that either recycled the crust, which reproduced by unilocular zoidangia, or developed into erect thalli. The latter, unlike typical gametophytic S. lomentaria, developed patchy sori of plurilocular zoidangia. Second, S. lomentaria displayed a direct‐type life cycle, in which progeny from erect individuals only developed into erect thalli and produced only plurilocular zoidangia. This constitutes the first experimental study on Scytosiphon from the Pacific coast of South America and the first report of S. tenellus on this coast. It is also the first report of the crustose stage of Scytosiphon appearing as a perennial and dominant algal species in a temperate rocky intertidal system.
LONG‐TERM CHANGES IN THE STRUCTURE OF INTERTIDAL ASSEMBLAGES AFTER INVASION BY SARGASSUM MUTICUM (PHAEOPHYTA)1
Authors: Sánchez Íñigo , Fernández Consolación , Arrontes Julio
Published: August 2005

The macroalgal assemblages at the low intertidal zone were studied at three localities on the north coast of Spain between 1977 and 2002. Two of these localities were invaded at the end of the 1980s by the brown seaweed Sargassum muticum (Yendo) Fensholt (Phaeophyta, Sargassaceae), whereas the third locality remained free of the invader. In 2002, distinct algal assemblages were noticed in invaded and noninvaded localities. No major changes were detected in the noninvaded locality. Apart from the obvious presence of S. muticum, the changes observed in the invaded localities included a significant reduction in abundance of the previous dominant species (the red alga Gelidium spinosum (S. G. Gmelin) P. C. Silva) as well as an increased number of species and diversity, increased primary productivity, and variations in the seasonal abundance patterns of some species. We speculate that the arrival of S. muticum had a negative effect on the dominant native G. spinosum, probably related to competition for light. This resulted in indirect positive effects on other species of the assemblage (such as Bifurcaria bifurcata R. Ross). Other small epiphytic opportunistic species might also have been benefited from the presence of S. muticum, because the invader has a rich associated epiphytic assemblage.
THE INFLUENCE OF FLUCTUATING LIGHT ON DIVERSITY AND SPECIES NUMBER OF NUTRIENT‐LIMITED PHYTOPLANKTON1
Authors: Flöder Sabine , Burns Carolyn W.
Published: August 2005

The influence of fluctuating light on diversity and species number of a natural phytoplankton assemblage competing for nutrients was investigated for 48 days under semicontinuous culture conditions. Light conditions were either changed periodically from high (65 μmol photons·m−2·s−1) to low intensity (15 μmol photons·m−2·s−1) at intervals of 1, 3, 6, and 12 days or fixed at constant light conditions of intermediate intensity (40 μmol photons·m−2·s−1). Fluctuating light at intervals of 1–12 days significantly affected phytoplankton diversity. The development of phytoplankton communities differed in treatments with different light regimes. In treatments with long light intervals, species abundance oscillated with the light phases. Differences in the temporal development of phytoplankton communities resulted in hump‐shaped relations between the interval length of the light phases and both species number and diversity index and can be explained by the intermediate disturbance hypothesis. Fluctuating light tends to sustain phytoplankton diversity under nutrient limitation if the light regime changes in the order of several days. This indicates that temporal changes in weather regime are important in preventing competitive exclusion of phytoplankton species in nature.
GENETIC AND MORPHOLOGICAL IDENTIFICATION OFFUCUS RADICANSSP. NOV. (FUCALES, PHAEOPHYCEAE) IN THE BRACKISH BALTIC SEA1
Authors: Bergström Lena , Tatarenkov Andrey , Johannesson Kerstin , Jönsson Rita B , Kautsky Lena
Published: August 2005

Brown seaweeds of the genusFucusoccupy a wide variety of temperate coastal habitats. The genus is evolutionary dynamic with recent radiations to form morphologically distinct taxa. In the brackish Baltic Sea, fucoids are the only perennial canopy‐forming macroalgae. The most northern populations ofFucusoccur permanently submerged in extremely low salinity (3–5 psu). These are currently referred to asFucus vesiculosusL. but are morphologically distinct with a narrow frond without bladders. We report here that a population of this unique morphotype is reproductively isolated from a truly sympatric population of commonF. vesiculosusand conclude that the northern morphotype represents a previously undescribed species. We describeFucus radicanssp. nov., which is attached and dioecious with broadly elliptic receptacles, characterized by a richly branched narrow flat frond (2–5 mm), short thallus (<26 cm), and a high capacity for vegetative recruitment of attached plants. Analysis of five highly polymorphic microsatellite DNA loci showed genetic differentiation between sympatric populations ofF. radicansandF. vesiculosus, whereas allopatric populations of the same species revealed a coherent pattern of genetic variation. Sequences of the RUBISCO region inF. radicanswere identical to or differing at only one to two dinucleotide positions from those ofF. vesiculosus, indicating a recent common origin of the two species.
Design of Case‐controls Studies with Unscreened Controls
Authors: Moskvina V. , Holmans P. , Schmidt K. M. , Craddock N.
Published: September 2005

Traditionally in genetic case‐control studies controls have been screened to exclude subjects with a personal history of illness. This control group has the advantage of optimal power to detect loci involved in illness, but requires more work and may incur substantial cost in recruitment. An alternative approach to screening is to use unscreened controls sampled from the general population. Such controls are generally plentiful and inexpensive, but in general there is a risk that some may have the same disease as the cases, which will reduce power to detect associations. We have quantified the extent of this power loss, and produced mathematical formulae for the number of unscreened controls necessary to achieve the same power as a fixed sample of screened controls. The effect of using unscreened controls will also depend on the ratio of the number of screened controls to cases specified in the original study design, and this is also investigated. We have also investigated the cost‐benefits of the screened and unscreened approaches, according to variation in the relative costs of sampling screened and unscreened controls, together with genotyping costs. We have, thus, identified the range of situations in which using unscreened controls is a cost‐effective alternative to the screened control method and could be considered when designing a study. In many of the typical, real‐world situations in complex genetics, the use of unscreened controls is potentially cost‐effective and can, in general, be considered for disorders with population prevalence Kp < 0.2. With the steady reduction in genotyping costs and the availability of common sets of “population controls” this design is likely to become increasingly cost effective.
High‐Resolution mtDNA Studies of the Indian Population: Implications for Palaeolithic Settlement of the Indian Subcontinent
Authors: Barnabas S. , Shouche Y. , Suresh C. G.
Published: August 2005

The population of the Indian subcontinent represents a very complex social and cultural structure. Occupying a geographically central position for the early modern human migrations, indications are that the founder group that migrated out of East Africa also reached India. In the present study we used the twin strategy of mapping the whole mitochondrial DNA (mtDNA) using the standard 14 restriction enzymes, and sequencing the non‐transcribed HVSI region, to derive maximum maternal lineages from a sample of non‐tribal Indians. The essential features of the reduced median network of the two datasets were the same. Both showed two demographic expansions of two major haplogroups, ‘M’ and ‘N’. The reduced median network was drawn with inputs from other studies on the Indian population, and correlated with data from other ethnic populations. The coalescence time of expansions and genetic diversity were estimated.

A reduced median network was also drawn combining data from studies on Africans, Southeast Asians and West‐Eurasians, tracing the migration of ‘M’ from East Africa to India. A time estimate of the migration of major mtDNA haplogroups from Africa was attempted. The comparison of a set of Indian maternal lineages belonging to different geographical regions of the country, with other populations revealed the in‐situ differentiation and antiquity of the Indian population. Our analysis places the ‘southern route’ migration as the source of haplogroup ‘M’. Multiple migrations might have brought the other major haplogroups, ‘N’ and ‘R’, found in our sample to India. Archaeological evidence of modern humans in the subcontinent supports this mtDNA study.
Golli‐MBP Copy Number Analysis by FISH, QMPSF and MAPH in 195 Patients with Hypomyelinating Leukodystrophies
Authors: Vaurs‐Barriere C. , Bonnet‐Dupeyron M‐N. , Combes P. , Gauthier‐Barichard F. , Reveles X. T. , Schiffmann R. , Bertini E. , Rodriguez D. , Vago P. , Armour J. A. L. , Saugier‐Veber P. , Frebourg T. , Leach R. J. , Boespflug‐Tanguy O.
Published: August 2005

The inherited disorders of CNS myelin formation represent a heterogeneous group of leukodystrophies. The proteolipoprotein (PLP1) gene has been implicated in two X‐linked forms, Pelizaeus‐Merzbacher disease (PMD) and spastic paraplegia type 2, and the gap junction protein α12 (GJA12) gene in a recessive form of PMD. The myelin basic protein (MBP) gene, which encodes the second most abundant CNS myelin protein after PLP1, presents rearrangements in hypomyelinating murine mutants and is always included in the minimal region deleted in 18q‐ patients with an abnormal hypomyelination pattern on cerebral MRI. In this study, we looked at the genomic copy number at the Golli‐MBP locus in 195 patients with cerebral MRI suggesting a myelin defect, who do not have PLP1 mutation. Although preliminary results obtained by FISH suggested the duplication of Golli‐MBP in 3 out of 10 patients, no abnormal gene quantification was found using Quantitative Multiplex PCR of Short Fluorescent fragments (QMPSF), Multiplex Amplifiable Probe Hybridization (MAPH), or another FISH protocol using directly‐labelled probes. Pitfalls and interest in these different techniques to detect duplication events are emphasised. Finally, the study of this large cohort of patients suggests that Golli‐MBP deletion or duplication is rarely involved in inherited defects of myelin formation.
Tests of Association Between Quantitative Traits and Haplotypes In A Reduced‐Dimensional Space
Authors: Sha Qiuying , Dong Jianping , Jiang Renfang , Zhang Shuanglin
Published: August 2005

Candidate gene association tests are currently performed using several intragenic SNPs simultaneously, by testing SNP haplotype or genotype effects in multifactorial diseases or traits. The number of haplotypes drastically increases with an increase in the number of typed SNPs. As a result, large numbers of haplotypes will introduce large degrees of freedom in haplotype‐based tests, and thus limit the power of the tests.

In this study we propose using the principal component method to reduce the dimension, and then construct association tests on the lower‐dimensional space to test the association between haplotypes and a quantitative trait using population‐based samples. The proposed method allows ambiguous haplotypes. We use simulation studies to evaluate the type I error rate of the tests, and compare the power of the proposed tests with that of the tests without dimension reduction, and the tests with dimension reduction by merging rare haplotypes. The simulation results show that the proposed tests have correct type I error rates and are more powerful than other tests in most cases considered in our simulation studies.
Genome‐Wide Scan for Loci Influencing Quantitative Immune Response Traits in the Belém Family Study: Comparison of Methods and Summary of Results
Authors: Wheeler E. , Miller E. N. , Peacock C. S. , Donaldson I. J. , Shaw M.‐A. , Jamieson S. E. , Blackwell J. M. , Cordell H. J.
Published: August 2005

Here we report the results from a genome‐wide linkage scan to identify genes and chromosomal regions that influence quantitative immune response traits, using multi‐case leprosy and tuberculosis families from north‐eastern Brazil. Total plasma IgE, antigen‐specific IgG to Mycobacterium leprae soluble antigen (MLSA), M. tuberculosis soluble antigen (MTSA) and M. tuberculosis purified protein derivative (PPD), and antigen‐specific lymphocyte proliferation (stimulation index or SI) and interferon‐γ (IFN‐γ) release to MLSA and PPD, were measured in 16 tuberculosis (184 individuals) and 21 leprosy (177 individuals) families. The individuals were genotyped at 382 autosomal microsatellite markers across the genome. The adjusted immune‐response phenotypes were analysed using a variety of variance components and regression‐based methods. These analyses highlighted a number of practical issues and problems with regard to implementation of the methods and, interestingly, differences were observed between several standard statistical and genetic analysis packages used. From this we determined that, for this set of traits in these pedigrees, significant p values for linkage using variance components analysis, supported by significance using the Visscher‐Hopper modification of the Haseman‐Elston method, provided the most compelling evidence for linkage. Using these criteria, linkage (5.8 × 10−5 < p < 0.008) was seen for: total plasma IgE on chromosome 2; IgG to MLSA on chromosomes 8, 17 and 21; IgG to PPD on chromosome 12; SI to PPD on chromosome 1; IFN‐γ to MLSA on chromosomes 6, 7, 10, 12 and 14; and IFN‐γ to PPD on chromosomes 1, 16 and 19.
A GENETIC MARKER TO SEPARATEEMILIANIA HUXLEYI(PRYMNESIOPHYCEAE) MORPHOTYPES1
Authors: Schroeder Declan C. , Biggi Gaia F. , Hall Matthew , Davy Joanne , Martínez Joaquín Martínez , Richardson Anthony J. , Malin Gillian , Wilson William H.
Published: August 2005

Emiliania huxleyi(Lohm.) Hay and Mohler is a ubiquitous unicellular marine alga surrounded by an elaborate covering of calcite platelets called coccoliths. It is an important primary producer involved in oceanic biogeochemistry and climate regulation. Currently,E. huxleyiis separated into five morphotypes based on morphometric, physiological, biochemical, and immunological differences. However, a genetic marker has yet to be found to characterize these morphotypes. With the use of sequence analysis and denaturing gradient gel electrophoresis, we discovered a genetic marker that correlates significantly with the separation of the most widely recognized A and B morphotypes. Furthermore, we reveal that the A morphotype is composed of a number of distinct genotypes. This marker lies within the 3′ untranslated region of a coccolith associated protein mRNA, which is implicated in regulating coccolith calcification. Consequently, we tentatively termed this marker the coccolith morphology motif.
Psychometric Properties of the 15‐Item Geriatric Depression Scale in Functionally Impaired, Cognitively Intact, Community‐Dwelling Elderly Primary Care Patients
Authors: Friedman Bruce , Heisel Marnin J. , Delavan Rachel L.
Published: September 2005

Objectives: To examine the psychometric properties of the 15‐item Geriatric Depression Scale (GDS‐15), a brief depression screening measure.

Design: Cross‐sectional.

Setting: Nineteen counties in western New York, West Virginia, and Ohio.

Participants: Nine hundred sixty functionally impaired, cognitively intact, community‐dwelling primary care patients aged 65 and older.

Measurements: The GDS‐15, major depression as measured using the Mini‐International Neuropsychiatric Interview, depressed mood, life satisfaction, suicidal ideation, and reported suicide attempts.

Results: Exploratory factor analyses suggested a two‐factor structure for the GDS‐15 in this category of patients, with component subscales assessing depression and positive affect. Cronbach alpha coefficients provide evidence for moderate, although acceptable, internal consistency reliability. Significant associations between the GDS‐15 and measures of depressed mood, life satisfaction, and suicidal ideation demonstrated construct validity, whereas acceptable sensitivity and specificity to discriminate between depressed and nondepressed patients demonstrated criterion validity. Internal consistency reliability and construct validity did not differ significantly between patients with low and high functional impairment. A significant weakness of the scale is its low correlation with suicide attempt status.

Conclusion: In general, this study provides evidence of impressive psychometric properties of the GDS‐15 when administered to a sample of functionally impaired, cognitively intact, community‐dwelling primary care patients.
Association Between Parkinson's Disease and Low Bone Density and Falls in Older Men: The Osteoporotic Fractures in Men Study
Authors: Fink Howard A. , Kuskowski Michael A. , Orwoll Eric S. , Cauley Jane A. , Ensrud Kristine E. ,   for the Osteoporotic Fractures in Men (MrOS) Study Group
Published: September 2005

Objectives: To examine the association between Parkinson's disease (PD) and bone mineral density (BMD) and risk of falls.

Design: Cross‐sectional and prospective cohort study.

Setting: Six U.S. clinical centers.

Participants: Five thousand nine hundred ninety‐five community‐dwelling, ambulatory men aged 65 and older.

Measurements: History of physician‐diagnosed PD was ascertained from participant self‐report. BMD was measured at the hip and spine using dual energy x‐ray absorptiometry (DEXA) and quantitative computed tomography (QCT). Incident falls were ascertained for 1 year using mailed queries.

Results: Fifty‐two participants (0.9%) reported a history of PD. In multivariate models, PD was associated with significantly lower BMD at the spine (−4.9%, P=.04) and total hip (−5.3%, P=.007) using DEXA and at the spine (−6.7%, P=.05) and total hip (−8.2%, P=.03) using QCT. PD was associated with a nearly three times greater age‐adjusted risk of multiple future falls (odds ratio (OR)=2.91, 95% confidence interval (CI)=1.55–5.46). Further adjustment for history of multiple falls in the year before baseline attenuated this risk, but it remained significant (OR=2.30, 95% CI=1.15–4.59).

Conclusion: In this cohort of older men, PD was associated with lower BMD at the hip and spine, measured using areal and volumetric BMD, as well as increased falls. Clinicians should consider screening older men with PD for osteoporosis.
Reliability and Validity of a Steadiness Score
Authors: Clark Daniel O. , Callahan Christopher M. , Counsell Steven R.
Published: September 2005

Objectives: To determine the internal consistency and construct and predictive validity of three survey questions regarding steadiness in a sample of community‐dwelling lower‐income older adults.

Design: A 6‐month prospective cohort study.

Setting: Community‐based.

Participants: Three hundred fifty‐seven older adults who completed a baseline and 6‐month follow‐up interviewer‐administered survey. These older adults received care at a single, public health system and were judged by insurance status to be of low income.

Measurements: Self‐report measures of steadiness while walking and transferring; difficulty in mobility, activities of daily living (ADLs), and instrumental activities of daily living (IADLs); chronic illness; falls; hospitalization; and sociodemographic characteristics.

Results: The three steadiness questions showed good internal consistency (0.88); construct validity in Pearson correlations with mobility (0.57), ADL (0.53), and IADL scores (0.41); and predictive validity. With regard to predictive validity, steadiness was predictive of falls, hospitalization, and decline in ADL and IADL function over a subsequent 6‐month period.

Conclusion: Steadiness questions are a potentially valuable addition to survey research and clinical screening to identify persons with current impairment status and falls and disability risk.
Frailty in Older Mexican Americans
Authors: Ottenbacher Kenneth J. , Ostir Glenn V. , Peek M. Kristen , Snih Soham Al , Raji Mukaila A. , Markides Kyriakos S.
Published: September 2005

Objectives: To identify sociodemographic characteristics and health performance variables associated with frailty in older Mexican Americans.

Design: A prospective population‐based survey.

Setting: Homes of older adults living in the southwest.

Participants: Six hundred twenty‐one noninstitutionalized Mexican‐American men and women aged 70 and older included in the Hispanic Established Populations for Epidemiologic Study of the Elderly participated in a home‐based interview.

Measurements: Interviews included information on sociodemographics, self‐reports of medical conditions (arthritis, diabetes mellitus, heart attack, hip fracture, cancer, and stroke) and functional status. Weight and measures of lower and upper extremity muscle strength were obtained along with information on activities of daily living and instrumental activities of daily living. A summary measure of frailty was created based on weight loss, exhaustion, grip strength, and walking speed. Multivariable linear regression identified variables associated with frailty at baseline. Logistic regression examined variables predicting frailty at 1‐year follow‐up.

Results: Sex was associated with frailty at baseline (F=4.28, P=.03). Predictors of frailty in men included upper extremity strength, disability (activities of daily living), comorbidities, and mental status scores (Nagelkerke coefficient of determination (R2)=0.37). Predictors for women included lower extremity strength, disability (activities of daily living), and body mass index (Nagelkerke R2=0.29). At 1‐year follow‐up, 83% of men and 79% of women were correctly classified as frail.

Conclusion: Different variables were identified as statistically significant predictors of frailty in Mexican‐American men and women aged 70 and older. The prevention, development, and treatment of frailty in older Mexican Americans may require consideration of the unique characteristics of this population.
Comorbidity Is a Better Predictor of Impaired Immunity than Chronological Age in Older Adults
Authors: Castle Steven Charles , Uyemura Koichi , Rafi Asif , Akande Omosalewa , Makinodan Takashi
Published: September 2005

Objectives: To determine whether high level of comorbidity, measured using a standardized instrument, can predict impaired immunity in older adults.

Setting: Geriatric outpatient Clinic and Nursing Home Care Unit of Veterans Affairs Greater Los Angeles Healthcare System.

Participants: Fifteen men aged 51 to 95 with varying levels of chronic illness.

Measurements: Disease burden was measured using the Cumulative Illness Rating Scale (CIRS) and immunity using proliferation of T cells induced by phytohemagglutinin (PHA) and production of interleukin (IL)‐12, a proinflammatory cytokine that promotes T helper cell–dependent immune response, and IL‐10, a cytokine that inhibits T helper cell–dependent immune response, in response to mitogenic stimulation of peripheral blood mononuclear cells.

Results: With increasing comorbidity (increase in CIRS score) in older adults, there is a proportional decrease in immune response (decrease in T cell proliferation and IL‐12 production and increase in IL‐10 production in response to PHA stimulation). Neither immune response nor CIRS score was significantly correlated with chronological age in this sample of older adults with varying degrees of chronic illness.

Conclusion: This study demonstrates that the level of comorbidity correlates with the magnitude of immune response in older adults and suggests that the CIRS could be used to determine the magnitude of impaired immunity in older adults with different specific illnesses and different levels of severity.
Disseminated Intravascular Coagulation as a Complication of Radiofrequency Catheter Ablation of Atrial Fibrillation
Authors: PARK HYUNG‐WOOK , CHO SANG‐HEE , KIM KYE‐HUN , CHO JEONG‐GWAN
Published: August 2005

Since Haissaguerre and his colleagues demonstrated the importance of the pulmonary veins in the generation of atrial fibrillation (AF) in 1998, a variety of different ablative interventions have been performed to eliminate AF. Various complications related to catheterization, ablation itself including pulmonary vein stenosis, pericardial effusion, stroke, and atrioesophageal fistula have been reported. Disseminated intravascular coagulation (DIC) is a systemic syndrome characterized by enhanced activation of coagulation with some intravascular fibrin formation and deposition. This is the first report, to our knowledge, of a patient whose condition was complicated by DIC after segmental ostial isolation of pulmonary veins for persistent AF. The patient has completely recovered from the DIC by hemodialysis, administration of blood constituents for 15 days.
Repolarization Abnormality for Prediction of All‐Cause and Cardiovascular Mortality in American Indians: The Strong Heart Study
Authors: OKIN PETER M. , MALIK MAREK , HNATKOVA KATERINA , LEE ELISA T. , GALLOWAY JAMES M. , BEST LYLE G. , HOWARD BARBARA V. , DEVEREUX RICHARD B.
Published: August 2005

Background: Analysis of electrocardiographic (ECG) repolarization abnormality using QTc interval and principal component analysis (PCA) of the T‐wave vector predict all‐cause and cardiovascular (CV) mortality. Novel descriptors of T‐wave morphology have been suggested as measures of repolarization heterogeneity and adverse prognosis. However, whether these T‐wave descriptors provide prognostic information beyond QTc and the PCA ratio has not been examined.

Methods and Results: Predictive values of QTc, PCA, and novel ECG variables characterizing the T‐wave loop were assessed in 1,729 American Indian participants in the first Strong Heart Study exam. T‐loop morphology was quantified by the ratio of the second to first eigenvalues of the T‐wave vector (PCA ratio), T‐loop area (TLA) projected onto the dominant vector plane, T‐wave morphology dispersion (TMD) and by the sum of the squares of the fourth to eighth eigenvalues, the T‐wave residuum (TWR). After mean follow‐up of 4.8 ± 0.8 years, there were 183 deaths from all causes, including 51 CV deaths. In univariate Cox analyses, prolonged QTc, increased PCA ratio, TLA, TMD, and TWR were significant predictors of all‐cause and CV mortality (P < 0.001). In multivariate Cox analyses adjusting for demographic and clinical risk factors for mortality, increased PCA ratio (chi‐square = 7.9, P = 0.005) and TWR (chi‐square = 5.3, P = 0.022) remained significant predictors of CV mortality and increased QTc (chi‐square = 12.1, P < 0.001) and TWR (chi‐square = 6.0, P = 0.014) of all‐cause mortality. Addition of TWR to the model with clinical variables and the PCA ratio for CV mortality and to the model with clinical variables and prolonged QTc for all‐cause mortality increased prognostic value of each model (increase in overall chi‐square from 287.5 to 301.9 and from 221.5 to 230.3, respectively).

Conclusion: Novel descriptors of T‐wave complexity provide additional prognostic information beyond QTc and PCA ratio for prediction of all‐cause and CV mortality.
Atrial Fibrillation in Patients with a Dual Defibrillator: Characteristics of Spontaneous and Induced Episodes and Effect of Ventricular Tachyarrhythmia Induction
Authors: BORIANI GIUSEPPE , RAVIELE ANTONIO , BIFFI MAURO , GASPARINI GIANNI , MARTIGNANI CRISTIAN , VALZANIA CINZIA , DIEMBERGER IGOR , CORRADO ANDREA , RACITI GIOVANNI , BRANZI ANGELO
Published: August 2005

Background: The pattern of FF intervals during atrial fibrillation (AF) has been analyzed in induced and spontaneous AF episodes, after the induction of ventricular fibrillation (VF) and after atrial shock, in order to suggest practical considerations for AF management in patients implanted with antitachycardia devices.

Methods: In 13 patients implanted with a dual‐chamber defibrillator, FF intervals were analyzed during two separate induced AF episodes, before and after VF induction over AF, as well as during spontaneous AF episodes and after unsuccessful atrial shocks. The following parameters were considered: mean atrial cycle length (CL), atrial CL stability, and standard deviation of the atrial cycle.

Results: The AF pattern had comparable characteristics considering two separate inductions of AF, as well as spontaneous AF episodes. Ventricular tachyarrhythmia induction resulted in a shortening of atrial CL (P < 0.02) and in a less organized AF pattern (P < 0.005). Changes in the FF interval after ineffective shock therapy showed a shortening of AF cycles after shocks with energies far below the defibrillation threshold.

Conclusions: (a) The AF pattern is reproducible in separate inductions of sustained AF and in spontaneous episodes, (b) dynamic changes involving a shortening of the AF cycle and an evolution to a less homogeneous pattern occur after VF induction, revealing a complex interplay between AF and VF, and (c) FF interval analysis after ineffective shock delivery may allow the relationship between delivered shock energy and effective defibrillation energy to be estimated, thereby providing practical suggestions for step‐up protocols in atrial cardioversion.