bluuebunny/crossref_metadata_2025_split huggingface dataset:
The evolution of silicification in diatoms: inescapable sinking and sinking as escape?
Authors: Raven J. A. , Waite A. M. 
Published: December 2004

SummaryThe silicified bipartite cell walls of diatoms (Bacillariophyceae) are produced in intracellular compartments by precipitation from supersaturated Si(OH)4and are then externalized. Fossil evidence of silicification is for marine, probably neritic, centric diatoms from approx. 120 Mya. Regardless of the initial selective significance of silicification, and of other current roles of silicification, the increased density resulting from silicification increases the sinking rate of cells; this can be partly or wholly offset by regulation of the protoplast solute content. Acclimatory and regulatory changes in silicification (relatively slow), and intracellular solute composition (relatively rapid), and intracellular solute composition (relatively rapid) of marine diatoms alter cell density over periods of hours to days. Density changes via changes in resource supply and, probably, parasitism, would move cells into optimal resource supply conditions, and remove parasitized, infective cells from surface populations of uninfected cells. Regulation of sinking rate could have been the first function of external or internal silica if the earliest silicified diatoms were planktonic.ContentsI.Introduction46II.Phylogeny of diatoms and the habitat of the earliest diatoms46III.Origin of the silicon requirement in diatoms46IV.The phylogeny and ontogeny of turgor‐ resistant silicified walls47V.Possible selective advantages of silicified walls49VI.Conclusions57Acknowledgements57References57
Cell biology of the plant Golgi apparatus
Authors: Hawes Chris 
Published: December 2004

SummaryThe higher plant Golgi apparatus, comprising many individual stacks of membrane bounded cisternae, is one of the most enigmatic of the cytoplasmic organelles. Not only can the stacks receive material from the endoplasmic reticulum, process it and target it to the correct cellular destination, but they can also synthesise and export complex carbohydrates and lipids and most likely act as one end point of the endocytic pathway. In many cells such processing and sorting can take place while the stacks are moving within the cytoplasm and, remarkably, the organelle manages to retain its structural integrity. This review considers some of the latest data and views on transport both to and from the Golgi and the mechanisms by which such activity is regulated.

Contents

Summary
29

I.
Introduction
29

II.
What is the plant Golgi apparatus?
30

III.
Out of the ER
31

IV.
Regulation of ER to Golgi transport
32

V.
Retrograde transport – Golgi to ER – the role of ARF and COPI
35

VI.
Transport down the stack
37

VII.
Targeting within the Golgi
37

VIII.
Holding it all together
38

IX.
Exit from the stack
39

X.
Roles for lipids
40

XI.
Conclusions
40

Acknowledgements
40

Note added in proof
41

References
41
Ethnicity, gender, and age effects on adrenoceptors and physiological responses to emotional stress
Authors: Suarez Edward C. , Saab Patrice G. , Llabre Maria M. , Kuhn Cynthia M. , Zimmerman Eugene 
Published: December 2004

AbstractWe examined the unique and joint effects of ethnicity, gender, and age on cardiovascular and catecholamine responses to the anger recall interview, and β2‐adrenergic receptor density and function on peripheral blood mononuclear cells. Participants were 179 nonsmoking, normotensive men and women aged 18–49 years. All subjects showed similar blood pressure increases during the anger recall interview. Black men, however, showed the smallest increases in heart rate in conjunction with an attenuated peripheral vasodilatation. Black women and Whites showed similar increases in heart rate and peripheral vasodilatation. Increasing age was associated with greater norepinephrine increases to anger recall in Black males. Black men also exhibited higher epinephrine levels throughout the protocol, higher dissociation constant to 125I‐pindolol, and age‐dependent increases in β2‐receptor density. Relative to Whites and Black females, arousal of negative affect in Black males led to a pattern of sympathetic nervous system activity that may help explain the higher prevalence of hypertension in this population.
Autonomic and behavioral responding to concealed information: Differentiating orienting and defensive responses
Authors: Verschuere Bruno , Crombez Geert , De Clercq Armand , Koster Ernst H. W. 
Published: December 2004

AbstractA mock crime experiment was conducted to examine whether enhanced responding to concealed information during a polygraph examination is due to orienting or defensive responding. Thirty‐six undergraduate students enacted one of two mock crimes. Pictures related to both crimes were presented while heart rate, magnitude of the skin conductance response, and reaction times to a secondary probe were measured. Compared to control pictures, participants showed heart rate deceleration and enhanced electrodermal responding to pictures of the crime they had committed. Probe reaction times did not differ significantly between crime and control pictures. The present findings support the idea that the orienting reflex accounts for the enhanced responding to concealed information. Theoretical and practical implications of the orienting account are discussed.
Word‐specific cortical activity as revealed by the mismatch negativity
Authors: Pulvermüller Friedemann , Shtyrov Yury , Kujala Teija , Näätänen Risto 
Published: December 2004

AbstractNeurophysiological brain activity evoked by individual spoken words and pseudowords was recorded and the mismatch negativity (MMN), an automatic index of experience‐dependent auditory memory traces, was calculated. Consistent with earlier reported results, the MMN response to word‐final syllables was enhanced compared with that elicited by the same syllables placed in a pseudoword context. Here we now demonstrate that the enhancement of the MMN elicited by two individual words showed different scalp topographies. The early word‐specific brain activity is consistent with the assumption that the memory traces activated by individual words are carried by large neuronal ensembles that differ in their distributions over the cortex. Current source estimates localized the between‐word differences in the right hemisphere and in parieto‐occipital left‐hemispheric areas. The differential brain responses to individual words appeared as early as ∼100 ms after the recognition points of the words, suggesting that their specific memory traces become active almost immediately after the information in the acoustic input is sufficient for word identification.
Differential analysis in the time domain of the baroreceptor cardiac reflex sensitivity as a function of sequence length
Authors: Reyes del Paso Gustavo A. , Hernández José A. , González M. Isabel 
Published: December 2004

AbstractAnalysis of baroreceptor sensitivity (BRS) in the time domain through the spontaneous sequence method used a measure of BRS based on the average of all sequences detected, without making any distinction in cardiac cycle length. In this article, we study differentially the functioning of the baroreflex as a function of the length of the cardiac sequences (3, 4, 5, or 6 cardiac cycles). One hundred and four students performed three mental stress tasks: mental arithmetic, memory, and visual attention. The results show that (1) as sequence length decreases, the relationships between BRS and indexes of vagal cardiac control increase, (2) the BRS associated with the more short sequences (3 and 4 beats) is the most vulnerable to mental stress, particularly the mental arithmetic task, and (3) BRS increases progressively as sequence length decreases. These results suggest that the nature and functioning of the baroreflex differ as a function of the length of the cardiac sequences.
Plasma nitrotyrosine in reversible myocardial ischaemia: Table 1
Authors: Elfatih A , Anderson N R , Mansoor S , Ahmed S , Horton R , Holland M R , Gama R 
Published: December 2004

Background:Nitric oxide (NO) plays a vital role in vascular homeostasis and in the pathophysiology of coronary heart disease. Its metabolites, nitrite and nitrate, have vasculoprotective properties, whereas peroxynitrite, an oxidant metabolite of NO, is cytotoxic and can aggravate myocardial damage during ischaemic reperfusion injury. Peroxynitrite nitrates free and protein bound tyrosine residues to produce nitrotyrosine. The measurement of nitrotyrosine provides an indirect estimation of plasma peroxynitrite concentrations.Aims:To measure plasma nitrotyrosine concentrations to see whether peroxynitrite could contribute to myocardial dysfunction during myocardial ischaemia induced by an exercise tolerance test (ETT).Materials/Methods:Plasma free nitrotyrosine concentrations were compared before and after exercise in 29 subjects with a positive ETT and 34 subjects with a negative ETT.Results:Plasma nitrotyrosine concentrations were similar in patients with exercise induced myocardial ischaemia and controls.Conclusion:Peroxynitrite does not contribute to the myocardial dysfunction in reversible myocardial ischaemia.
Microsatellite analysis of the adenomatous polyposis coli (APC) gene and immunoexpression of β catenin in nephroblastoma: a study including 83 cases treated with preoperative chemotherapy
Authors: Ramburan A , Oladiran F , Smith C , Hadley G P , Govender D 
Published: December 2004

Aims:To determine whether microsatellite mutations of the adenomatous polyposis coli (APC) gene have pathological or prognostic significance in nephroblastomas and to correlate APC alterations with β catenin immunoexpression.Methods:One hundred nephroblastomas were analysed, 83 of which received preoperative chemotherapy. Normal and tumour DNA was isolated using standard proteinase K digestion and phenol/chloroform extraction from paraffin wax embedded tissue. Polymerase chain reaction using four APC microsatellite markers—D5S210, D5S299, D5S82, and D5S346—was performed and the products analysed. Immunohistochemistry was performed using the LSAB kit with diaminobenzidine as chromogen. Results were correlated with clinicopathological data using the χ2test.Results:Allelic imbalance/loss of heterozygosity was more frequent than microsatellite instability, with 30% of cases showing allelic imbalance/ loss of heterozygosity and 16% showing microsatellite instability. Although there was a significant correlation between the results for individual markers and the clinicopathological data, the overall results do not support a prognostic role for APC in nephroblastoma. Expression of β catenin was seen in 93% of cases. Staining was predominantly membranous, with epithelium, blastema, and stroma being immunoreactive. Cytoplasmic redistribution was seen in 58% of cases, but no nuclear staining was detected. No significant associations between β catenin expression and the clinicopathological parameters were found. Kaplan–Meier survival plots showed that patients with loss of membranous staining and pronounced cytoplasmic staining (score, 3) had a significantly shorter survival (p = 0.04; median survival, 5.87 months).Conclusion:Microsatellite analysis of APC and immunoexpression of β catenin did not provide significant pathological or prognostic information in this cohort of nephroblastomas.
Antimicrobial activity of UMFix tissue fixative
Authors: Cleary T J , Morales A R , Nadji M , Nassiri M , Vincek V 
Published: December 2004

Aims:The aim of this study was to determine the antimicrobial effects of UMFix, an alcohol based tissue fixative, on various microorganisms. The UMFix solution was compared with 10% neutral buffered formalin.Methods:Standard methods to determine microorganism colony counts were performed after exposure of the microorganisms to UMFix and 10% neutral buffered formalin.Results:After a short exposure, UMFix rapidly killed vegetative bacteria, yeasts, moulds, and viruses. Bacterial spores were resistant to killing by UMFix. All organisms were killed by the 10% neutral buffered formalin preparation.Conclusions:UMFix was microbicidal for vegetative bacteria, yeasts, and aspergillus species after a short exposure, although it was not active against spore forming bacillus species. The methanol content of the fixative was responsible for the killing effect of this fixative. No killing was seen when polyethylene glycol was used alone.
HOFER–ZEHNDER CAPACITY AND HAMILTONIAN CIRCLE ACTIONS
Authors: MACARINI LEONARDO 
Published: December 2004

We introduce the Hofer–Zehnder Γ-semicapacity [Formula: see text] of a symplectic manifold (M,ω) (or Γ-sensitive Hofer–Zehnder capacity) with respect to a subset Γ⊂π1(M)[Formula: see text] and prove that given a geometrically bounded symplectic manifold (M,ω) and an open subset N⊂M admitting a Hamiltonian free circle action with order greater than two then N has bounded Hofer–Zehnder Γ-semicapacity, where Γ⊂π1(N) is the subgroup generated by the orbits of the action. We give several applications of this result. Using Biran's decomposition theorem, we prove the following: let (M2n,Ω) be a closed Kähler manifold (n>2) with [Ω]∈H2(M,ℤ) and Σ a complex hypersurface representing the Poincaré dual of k[Ω], for some k∈ℕ. Suppose either that Ω vanishes on π2(M) or that k>2. Then there exists a decomposition of M into an open dense subset E such that E\Σ has finite Hofer–Zehnder Γ-semicapacity and an isotropic CW-complex, where Γ⊂π1(E\Σ) is the subgroup generated by the obvious circle action on the normal bundle of Σ. Moreover, we prove that if (M,Σ) is subcritical then M\Σ has finite Hofer–Zehnder Γ-semicapacity. We also show that given a hyperbolic surface M and TM endowed with the twisted symplectic form ω0+π*Ω, where Ω is the Kähler form on M, then the Hofer–Zehnder Γ-semicapacity of the domain Uk bounded by the hypersurface of kinetic energy k minus the zero section M0 is finite if k<1/2, where Γ⊂π1(Uk) is the subgroup generated by the fibers of SM. Finally, we consider the problem of the existence of periodic orbits on prescribed energy levels for magnetic flows. We prove that given any weakly exact magnetic field Ω on any compact Riemannian manifold M there exists a sequence of contractible periodic orbits of arbitrarily small energy, extending a previous result of Polterovich.
An Analysis of Stream Habitat Conditions in Reference and Managed Watersheds on Some Federal Lands within the Columbia River Basin
Authors: Kershner Jeffrey L. , Roper Brett B. , Bouwes Nicolaas , Henderson Richard , Archer Eric 
Published: December 2004

Abstract
The loss of both habitat quality and quantity for anadromous fish in the Columbia River basin has been identified as a major factor in the decline of many species and has been linked to a variety of land management activities. In this study, we compared stream reaches in watersheds representing both managed and reference conditions to determine whether we could detect differences in physical habitat variables. We divided stream habitat measures into three components: Stream banks, instream habitat (pools and pool depth), and stream substrate. We randomly sampled perennial streams within 261 sixth hydrologic unit code (HUC) stream reaches on federal lands in Idaho, Montana, Oregon, and Washington. The sample population represented stream reaches in 62 reference watersheds and 199 managed watersheds. An unbalanced, incomplete-block-design analysis of covariance (ANCOVA) was performed on each of the habitat variables using geology type as the block effect and bank-full width, stream gradient, and average precipitation as the covariates. Watersheds containing reference stream reaches had a slightly higher percentage of federal lands, were smaller, tended to occur at higher mean elevations, and received more annual precipitation than did the managed watersheds. We observed differences in most measures of stream habitat between reference and managed watersheds, generally in the direction we expected. Stream banks were more stable and more undercut in reference stream reaches. Pools in reference stream reaches were deeper than pools in managed stream reaches and had less fine sediment in pool tails. Analysis of covariance was an effective way to compare data across a large, relatively heterogeneous landscape where sample site stratification may be impractical or sample sizes are limited. We believe that the comparison of reference conditions to conditions across managed landscapes provides a credible way to report on the condition of these systems in lieu of trend information at individual sites.
Summer Movements within the Fish Community of a Small Montane Stream
Authors: Schmetterling David A. , Adams Susan B. 
Published: December 2004

Abstract
We studied movements by fishes in Chamberlain Creek, Montana, from 24 July to 16 August 2001. We operated six weirs with two-way traps and one additional upstream trap, separated by 14–1,596 m, to quantify the timing, direction, and distance of movements and to estimate fish populations in the study reaches. We trapped and marked 567 fish of seven species, including 368 westslope cutthroat trout Oncorhynchus clarkii lewisi and 172 sculpin (slimy sculpin Cottus cognatus and an unidentified species similar to mottled sculpin C. bairdii). We recaptured 173 westslope cutthroat trout and detected net movements as long as 1,581 m (median, 91 m). Bidirectional movements for 116 westslope cutthroat trout ranged from less than 18 to more than 1,581 m (median, 64 m). Sculpin moved as far as 209 m (median, 26 m). We estimate that 14% of sculpin and 48% of westslope cutthroat trout were mobile during the study. We captured all species more frequently at night or twilight (n = 296) than during the day (n = 83) and more frequently moving downstream (n = 419) than upstream (n = 277). These results demonstrate considerable summer movement by the fish community in a small stream.
Methodological Bias in Estimates of Strain Composition and Straying of Hatchery-Produced Steelhead in Lake Michigan Tributaries
Authors: Bartron Meredith L. , Swank Dave R. , Rutherford Edward S. , Scribner Kim T. 
Published: December 2004

Abstract
Steelhead Oncorhynchus mykiss were first introduced into the Great Lakes in the late 1800s. Subsequently, natural recruitment of steelhead from spawning runs in streams across the basin has been regularly supplemented by hatchery production of strains derived from widely dispersed locales within the species' native range. Estimates of hatchery contributions to the spawning runs of naturalized populations may be underrepresented by observations of marked fish, as not all hatchery fish are marked prior to release. To assess the potential bias in estimates of the hatchery contribution to steelhead spawning runs in four major rivers in Michigan, we used scale pattern analysis (SPA) to identify nonmarked hatchery fish and multilocus genotypes to estimate the proportional contributions of each hatchery strain to spawning runs. The four hatchery strains currently stocked are significantly genetically distinct (mean FST = 0.077), making it possible to identify specific strains by use of likelihood-based assignment tests. The differences between direct (mark observations) and indirect (SPA and genetic analysis) estimates of hatchery contribution were mainly due to variations in the percentage of hatchery fish marked by states prior to release and the potential for confusion between certain marks and injuries. By combining direct and indirect assessment methodologies, we estimated that the percentage of hatchery fish returning to the four rivers ranged from 13% to 31% of total spawning runs. The large contribution of hatchery fish to nonstocked rivers differed significantly from expectations of strain-specific stocking rates across the Lake Michigan basin and for individual streams, indicating high amounts of straying into Michigan streams.
Efficacy of a Chase Boat for Electrofishing Flathead Catfish in Three Oklahoma Reservoirs
Authors: Cunningham Kenneth K. 
Published: December 2004

Abstract
Electrofishing methods employed to sample flathead catfish Pylodictis olivaris in reservoirs can be labor-intensive when a chase boat is used to increase sampling efficiency. During summer 1997, I compared electrofishing results with and without a chase boat on three Oklahoma reservoirs. Capture efficiency, mean number of fish netted per 3-min sample, and length-frequency distribution were similar with and without a chase boat. I recommend discontinuing the use of a chase boat for sampling flathead catfish with electrofishing in reservoirs similar to those sampled in my study.
Fish Populations Associated with Habitat-Modified Piers and Natural Woody Debris in Piedmont Carolina Reservoirs
Authors: Barwick Robert D. , Kwak Thomas J. , Noble Richard L. , Barwick D. Hugh 
Published: December 2004

Abstract
A primary concern associated with reservoir shoreline residential development is reduction of littoral habitat complexity and diversity. One potential approach to compensate for this is the deployment of artificial-habitat modules under existing piers, but the benefit of this practice has not been demonstrated. To evaluate the effect of pier habitat modifications on fish populations in two Piedmont Carolina reservoirs, we studied 77 piers located on forty-seven, 100-m transects that were modified using plastic “fish hab” modules augmented with brush (brushed habs), hab modules alone (habs), or left unaltered for reference purposes. We sampled fish from all piers and transects during April, July, and October 2001 using a boat-mounted electrofisher. With few exceptions, catch rates were higher at brushed-hab piers and piers with habs than at reference piers during all seasons. Similarly, during spring and summer, fish abundance was generally higher on transects containing natural woody debris, brushed habs, and habs than on reference-developed transects; however, during fall, there were exceptions. Therefore, fish abundance associated with shorelines in these reservoirs appears to be related to the structural complexity of available habitat rather than structure composition. One year after installation, 92% of pier owners responding to a mail survey expressed satisfaction with pier modifications. Supplementing piers with habitat structures is recommended to enhance littoral habitat complexity for fishes in residentially developed reservoirs.
Evaluating Stream Habitat Survey Data and Statistical Power Using an Example from Southeast Alaska
Authors: Bryant Mason D. , Caouette John P. , Wright Brenda E. 
Published: December 2004

Abstract
Stream habitat surveys and watershed assessments have been developed and used as monitoring tools for decades. Most rely on type I error as the primary criterion, with minor consideration of statistical power and effect size. We test for statistical differences in fish habitat condition between harvested and nonharvested watersheds from habitat survey data collected in southeast Alaska. We apply statistical power analysis to judge whether nonsignificant results can be interpreted with confidence. None of the fish habitat variables we examined were significant at α = 0.05; however, several P-values were less than 0.10 and consistent differences between harvested and nonharvested reaches were observed among channel types. Statistical power is low and the probability of not detecting differences is high when the effect size, scaled to the standard deviation of the measurement, is small to medium. For large effect sizes, the ability to detect differences was greater but did not exceed 85% for any measurement. Statistical power, effect size, and biological significance of the outcome are important considerations when the results are interpreted and can lend additional information to managers making decisions with data that are less than perfect.