bluuebunny/crossref_metadata_2025 huggingface dataset:
Wild Thing: Less-domesticated mice harbor genetic secrets to long life
Authors: Davenport R. John
Published: August 2003

A life of leisure might seem attractive, but all that coddling could make one's genes go soft. Domesticated mice--selected for their ability to grow quickly, reproduce robustly, and mind their handlers--make experiments easy. Generations of captivity, however, might select against genes that could help them live longer, according to a new study.

In an effort to find mammalian genes that contribute to longevity, Klebanov and colleagues performed two breeding experiments. In each one, they carried out crosses with four strains of inbred mice to produce a genetically mixed population of grandchildren. One strain in each experiment originated from wild mice, while the others came from animals that had been domesticated prior to breeding. Then the researchers looked for genetic markers that tended to show up in long-lived offspring but not in individuals that died at a younger age. The resulting marker patterns led the team to two regions of the genome, one from each experiment, that were associated with longer living mice. The oldest 18% of animals that carried such tracts of DNA outlived the oldest 18% that did not by approximately 4 months. In both cases the markers that are linked to longevity come from strains derived from wild rather than domesticated mice.

No one can explain this result yet, but in general, animals that are larger and reproduce more tend not to live as long as their smaller and less fertile counterparts. Hence, the domestication process could select against genes that extend life-span. The researchers have yet to home in on the presumed longevity gene or genes that reside in the spans of DNA they identified. But the results hint that domesticated mice might lack the aging-related genes that geneticists are so wild about.

S. Klebanov, C. M. Astle, T. H. Roderick, K. Flurkey, J. R. Archer, J. Chen, D. E. Harrison, Maximum life spans in mice are extended by wild strain alleles.
Exp. Biol. Med.
226
, 854-859 (2001).
[Abstract]
[Full Text]

--Suggested by James M. Harper
Dementia with Lewy Bodies
Authors: Posner Holly , Chin Steven , Marder Karen
Published: August 2003

In this case study, we describe the symptoms, neuropsychological testing, and brain pathology of a man with dementia with Lewy bodies. Dementia with Lewy bodies might be the second most common form of degenerative dementia in the elderly. Progressive cognitive decline, well-formed visual hallucinations, and parkinsonism are core features of this disease. This case was marked by preserved verbal expression despite impairment in memory, visuospatial skills, and attention span. Development of visual symptoms and parkinsonism occurred very early in the course of the disease.
Obituary: IdG1-030, Long-Lived Mouse
Authors: Miller Richard A.
Published: August 2003

IdG1-030, the world's oldest normal lab mouse, died peacefully in his sleep on 15 November 2001, at the age of 1449 days, just 11 days shy of what would have been his fourth birthday.

Born and raised in a small plastic cage in Ann Arbor, Michigan, IdG1-030 was one of a set of quintuplets born to a mated pair whose own parents had romped, poor but free, in the barnyards of Moscow, Idaho. He was among the first volunteers for a National Institutes of Health-funded study to determine whether country mice might retain antiaging genes long ago lost by their effete town-and-gown cousins. IdG1-030 spent his entire life within 15 meters of his birthplace on shelf 4B, apparently content with a social circle consisting initially of three other males but then slowly shrinking, over the years, to a single idiosyncratic point. His devoted caretakers describe IdG1-030 as somewhat shy and certainly not prone to complaint, noting that he dealt with his late-life celebrity as the world's oldest living mouse with the same diffidence that typified his earlier, out-of-the-limelight career as just another research subject. His great age (roughly equivalent, at the end, to that of a 137-year-old human) did not, until the last day or two of his final illness, impair his zest for chewing wood chips or for doing pull-ups near the food hopper at the top of his cage.

Although encouraged by his friends and publicists to go for the international all-genotypes longevity record held by the longest lived Snell dwarf mouse (1451 days; see

Flurkey
et al.

), IdG1-030 seemed to have no interest in comparing his own life history with that of puny dwarves or emaciated, calorically restricted rodents. He was clearly willing to accept an asterisk in the record books as the price for a life of ready access to all-you-can-eat meals and the robust enjoyment of a fully loaded anterior pituitary gland.

Although childless (and, indeed, a lifelong virgin), IdG1-030 is survived by nine half-nieces and -nephews, 19 half-grandnieces and -grandnephews, and 28 great half-grandnieces and -grandnephews, all of them currently working in the research field.

--Richard A. Miller
This Is Your Brain ... And This Is Your Brain on Calcium
Authors: Leslie Mitch
Published: August 2003

Most older brains don't learn or remember as well as younger ones do. One possible reason is that rising calcium concentrations within neurons hamper memory and learning. Researchers have accumulated a small pile of supporting evidence for the calcium hypothesis, but key questions remain about calcium's interaction with other mechanisms of aging and its effects on neuron activity.
Oxygen? No Thanks, I'm on a Diet
Authors: Longo Valter D.
Published: August 2003

In yeast and worms, mutations that extend longevity appear to simulate starvation conditions. The
daf-2
pathway in worms plays a major role in life-span extension and in entry into the starvation-resistant and low-metabolism dauer phase. In a
recent study
published in
Science
Express on 13 June 2002, researchers screened for
Caenorhabditis elegans
mutants that survive in a low-oxygen environment and identified a number of
daf-2
mutants that are resistant to hypoxia. The implications of these results are discussed in this Perspective.
No Truth to the Fountain of Youth
Authors: Olshansky S. Jay , Hayflick Leonard , Carnes Bruce A.
Published: August 2003

The essay "

No Truth to the Fountain of Youth
" was published in the
Scientific American
special issue

The Science of Staying Young

in June 2002. In this article, the authors explain why it is important for the public to understand that no purported anti-aging remedy available has been shown to be effective.
High-Octane Endurance--Yeast in the Metabolic Fast Lane Live Longer
Authors: Strauss Evelyn
Published: August 2003

Yeast don't shoot craps or snort cocaine, but a different kind of fast life might invigorate them, according to new research. Many scientists have wondered whether slowing metabolism could prolong life. The findings suggest instead that speeding it up might do the trick, at least in yeast. They also tie together the effects of known life extenders, showing that calorie restriction harnesses a protein that governs aging, Sir2p. Although many questions remain about how faithfully the results will transfer to mammals, the work challenges some old ideas and hints that researchers should look at the relation between metabolism and longevity in a new way.
Auto Repair on the Aging Stem Cell Superhighway
Authors: Edelberg Jay M.
Published: August 2003

Adult bone marrow stem cells offer the potential for rejuvenation of diseased or damaged tissues and organs. The greatest need for such a treatment in older individuals is to counter age-associated predisposition to cardiovascular diseases. Unfortunately, changes in senescent vascular function might limit the recruitment of bone marrow-derived precursor cells. In order to provide the patient with the conduits required to deliver bone marrow cells to damaged tissues, it is essential to develop strategies to overcome these limitations. This effort will require novel approaches to reverse aging-associated vascular dysfunction, including reharnessing the potential of stem cells from the aging bone marrow for vascular repair.
The Drifter
Authors: Chen Ingfei
Published: August 2003

Harvard geneticist Gary Ruvkun spent part of the '70s wandering along the Pacific Coast and into South America. Since then his studies of a hibernation phase in the
Caenorhabditis elegans
life cycle have led him into the study of aging.
Titin--Springing Back to Youth?
Authors: Huq Fawzia , Heist E. Kevin , Hajjar Roger J.
Published: August 2003

Mutations in the muscle protein titin have been linked to dilated cardiomyopathy, a condition in which the heart chambers are enlarged and blood is ineffectively pumped, in humans and in animal models. This protein, which is a component of sarcomeres, provides essential scaffolding for other muscle proteins and acts as a spring to confer passive elasticity on the cardiomyocyte. Several titin isoforms exist, and they display varying size and degrees of elasticity. We review two interesting reports that show how variations in titin isoforms might be implicated in cardiac failure.
Broken Barrow
Authors: Beckman Mary
Published: August 2003

Protein involved in neurodegenerative disease loses ability to deliver molecules (Polyglutamine disease; Huntington's disease; Spinocerebellar ataxia).
Double Duty
Authors: Beckman Mary
Published: August 2003

Insulin-chomping protein might couple diabetes and Alzheimer's disease (Alzheimer's disease; Diabetes).
Help Available--Phenomenological Models for Research on Aging
Authors: Mitnitski Arnold , Rockwood Kenneth
Published: August 2003

In "Help Wanted: Physiologists for Research on Aging," George Martin challenged the scientific community to find better means of tackling aging of the whole organism. Although initiatives such as those proposed by Martin would be most welcome, we propose an additional means by which scientists can take into account the integrative response of the organism and its changes over time. This method consists of systematizing facts that cannot necessarily be explained by considering those facts in isolation.
Direct and Indirect Transcriptional Targets of DAF-16
Authors: Larsen Pamela L.
Published: August 2003

Several genes involved in the determination of life span have been identified by mutation in the free-living soil nematode
Caenorhabditis elegans
. One of the key pathways studied in the context of life span is the DAF-2 pathway. The
daf-2
gene is homologous to the insulin and insulin-like growth factor 1 receptor families. A downstream gene,
daf-16
, encodes a protein that is homologous to the forkhead transcription factor. A study by McElwee, Bubb, and Thomas, published in the current issue of
Aging Cell
, used genome-scale gene expression analysis to search for genes that are differentially expressed between long-lived
daf-2
(
e1370
) and short-lived
daf-16
(
m27
)
;daf-2
(
e1370
) animals. In doing so, they identified candidate direct and indirect targets of DAF-16. In this Perspective, I discuss the results of this study.
Casting Doubt
Authors: Seydel Caroline
Published: August 2003

New results challenge antioxidant's life-extending capabilities (Oxidative damage; Therapeutics).
Alzheimer's Disease, Neuropeptides, Neuropeptidase, and Amyloid-β Peptide Metabolism
Authors: Saito Takashi , Takaki Yoshie , Iwata Nobuhisa , Trojanowski John , Saido Takaomi C.
Published: August 2003

Amyloid-β peptide (Aβ), the pathogenic agent of Alzheimer's disease (AD), is a physiological metabolite in the brain. We have focused our attention and effort on elucidating the unresolved aspect of Aβ metabolism: proteolytic degradation. Among a number of Aβ-degrading enzyme candidates, we used a novel in vivo paradigm to identify a member of the neutral endopeptidase family, neprilysin, as the major Aβ catabolic enzyme. Neprilysin deficiency results in defects in the metabolism of endogenous Aβ 40 and 42 in a gene dose-dependent manner. Our observations suggest that even partial down-regulation of neprilysin activity, which could be caused by aging, can contribute to AD development by promoting Aβ accumulation. Moreover, we discuss the fact that an aging-dependent decline of neprilysin activity, which leads to elevation of Aβ concentrations in the brain, is a natural process that precedes AD pathology. In this Perspective, we hypothesize that neprilysin down-regulation has a role in sporadic AD (SAD) pathogenesis, and we propose that this knowledge be used for developing preventive and therapeutic strategies through use of a G protein-coupled receptor (GPCR).
Unraveling Chromosome Chaos
Authors: Leslie Mitch
Published: August 2003

Trimmed telomeres might provoke premature-aging disease (Ataxia-Telangiectasia; Telomeres).
Lasting Without Fasting
Authors: Davenport R. John
Published: August 2003

Zapping insulin signaling in fat helps well-fed mice persist (Insulin-related signaling; Diabetes).
When Tips Disappear, the End Is Near
Authors: Davenport R. John
Published: August 2003

Short telomeres presage mortality, but do they cause it? (Telomeres).
All in Your Mind
Authors: Helmuth Laura
Published: August 2003

Age changes the mind. Even healthy people with no neurodegenerative diseases have a different constellation of cognitive abilities when they're 80 than when they're 20. Fortunately, the aging mind doesn't face a simple, steep decline. Although aspects of memory and other skills decay linearly decade by decade, other abilities age gracefully: Vocabulary, for instance, seems to improve with time. In a new approach to understanding cognitive changes, researchers are recognizing that motivations and emotional values evolve over the life-span--and what people care about helps determine what they remember. The neuroanatomical bases of age-related cognitive changes are poorly understood, but much of the action appears to occur in the frontal lobes, possibly driven by a faltering dopamine system.
Out of the Lab, Into the Legislature
Authors: Ramsayer Kate
Published: August 2003

New Web site focuses on policy implications of aging-related research (Policy).
Catalytic, Oxidative Condensation of CH
4
to CH
3
COOH in One Step via CH Activation
Authors: Periana Roy A. , Mironov Oleg , Taube Doug , Bhalla Gaurav , Jones CJ
Published: August 2003

Acetic acid is an important petrochemical that is currently produced from methane (or coal) in a three-step process based on carbonylation of methanol. We report a direct, selective, oxidative condensation of two methane molecules to acetic acid at 180°C in liquid sulfuric acid. Carbon-13 isotopic labeling studies show that both carbons of acetic acid originate from methane. The reaction is catalyzed by palladium, and the results are consistent with the reaction occurring by tandem catalysis, involving methane C-H activation to generate Pd-CH
3
species, followed by efficient oxidative carbonylation with methanol, generated in situ from methane, to produce acetic acid.
The influence of partial harvesting and forest floor disturbance on nutrient availability and understory vegetation in boreal mixedwoods
Authors: Frey Brent R , Lieffers Victor J , Munson Alison D , Blenis Peter V
Published: August 2003

The impacts of partial cut systems on nutrient availability and understory vegetation are poorly understood. To examine these responses, white spruce dominated stands in the boreal mixedwood of Alberta were clear-cut or partial-cut and the forest floor treated by slash burning, mixing, mounding, or scalping in a split-plot design. Soil nutrient availability (ion exchange resin), net N mineralization (in situ incubations), and vegetation (density and cover) responses were assessed. With the exception of higher Mg availability in the clearcuts, differences in nutrient availability were driven by forest floor disturbance and not harvest method. Relative to controls, burning increased availability of NH4+, NO3, and P, and scalping increased Ca and Mg but diminished K. Controls had low levels of NO3. The mixing treatment substantially reduced net N mineralization. In terms of vegetation, partial cuts reduced root suckering by Populus spp. (Populus tremuloides Michx., Populus balsamifera L.) relative to clearcuts. Burning and mounding stimulated fireweed (Epilobium angustifolium L.) cover, while scalping increased Populus spp. sucker density. In contrast, mixing largely reduced vegetation establishment, likely because of the destruction of roots and rhizomes and reduced N supply. Nutrient availability and vegetation establishment were more strongly controlled by forest floor disturbance than by partial canopy retention.
A note on the relationship between the quadratic mean stand diameter and harmonic mean basal area under size-biased distribution theory
Authors: Gove J H
Published: August 2003

This note seeks to extend the utility of size-biased distribution theory as applied to forestry through two relationships regarding the quadratic mean stand diameter. First, the quadratic mean stand diameter's relationship to the harmonic mean basal area for horizontal point sampling, which has been known algebraically from early on, is proved under size-biased distribution theory. Second, a new result, which may prove most valuable in viewing the graphical representation of assumed distributions, is also derived. The results are also shown to apply to the basal area  size distribution, providing a unique duality between the two means.
Relations among larval tailed frogs, forest harvesting, stream microhabitat, and site parameters in southwestern British Columbia
Authors: Wahbe Tanya R , Bunnell Fred L
Published: August 2003

Amphibians are the most abundant vertebrates in many forests and have the potential to play a significant role in ecosystem dynamics. We examined the effects of logging on larval Ascaphus truei Stejneger in low-order streams. Density, biomass, and mean snoutvent length were greatest in streams flowing through old growth; however, effects associated with forest harvest depended on elevation, stream size, percent cover of sand, boulders, runs, and riffles. Density and biomass were highest in high-elevation streams where silt and algae were absent and where temperature and percent cover of sand were lowest. Larvae appeared to select pool, run, or riffle microhabitats depending on their body size or developmental stage, with larger and more developed larvae occupying faster stream sections. Logging history appears to have less influence on Ascaphus variables than do stream microhabitat and site. In our study, over 86% of the variation in both density and biomass was associated with stream and site parameters. Because our results suggest that forest disturbance has major impacts under only certain conditions, we recommend that the variability of stream microhabitat and site parameters be considered prior to making harvesting decisions when managing for Ascaphus and other organisms with similar habitat requirements.
An analysis of sucker regeneration of trembling aspen
Authors: Frey Brent R , Lieffers Victor J , Landhäusser Simon M , Comeau Phil G , Greenway Ken J
Published: August 2003

Aspen (Populus tremuloides Michx.) is a clonal tree species that commonly regenerates via root suckering after disturbance. This paper reviews the literature and identifies critical gaps in our understanding of the dynamics of aspen root suckering. The role of plant growth regulators (e.g., hormones, carbohydrates), environmental conditions (e.g., soil moisture, temperature, nutrient availability), overstory disturbance (e.g., harvesting, wildfire), ground disturbance (e.g., soil compaction, wounding or severing of roots), vegetation competition, predisturbance stand condition, and clonal (genetic) differences are discussed as they relate to sucker initiation, sucker growth, and (or) patterns of site establishment. The paper presents a series of conceptual figures summarizing our knowledge of the factors controlling suckering dynamics and identifies areas of future research.
Stand structure governs the crown collisions of lodgepole pine
Authors: Rudnicki Mark , Lieffers Victor J , Silins Uldis
Published: August 2003

We investigated tree sway and crown collision behavior of even-aged lodgepole pine (Pinus contorta Dougl. ex Loud. var. latifolia Engelm.) stands of different structure in Alberta, Canada, to examine how these factors might affect loss of leaf area as stands mature. The Two Creeks stand (TC) had high density and slender trees, while the Chickadee stand (CH) had stout trees. The TC stand was then thinned (TCT) to reduce the stand density. For each stand, simultaneous tree sways of a group of 10 trees were monitored with biaxial clinometers during wind speed of 5 m/s (canopy top). Crown collisions were reconstructed by combining sway displacement of individual trees with their respective crown dimensions. Comparing the sway statistics between stands with contrasting mean bole slenderness (TC and CH) indicated that more slender trees have greater sway displacements, faster sway speeds, and a greater depth of collision. Disturbance by thinning increased sway displacements, sway speeds, and depth of collisions at TCT. Tree sway patterns were circular in shape and not aligned with wind direction, but patterns were elongated after thinning. This demonstrates the high frequency of crown collision experienced by stands with slender trees and supports the notion that crown collisions result in empty space between crowns of trees.
Stem hydraulic properties and growth in lodgepole pine stands following thinning and sway treatment
Authors: Liu Xiaodong , Silins Uldis , Lieffers Victor J , Man Rongzhou
Published: August 2003

The objective of this study was to explore the effects of wind-caused sway on the growth and stem hydraulic properties of fire-origin juvenile lodgepole pine (Pinus contorta Dougl. ex Loud.) stands after thinning. Nine plots were thinned and trees were treated to suppress or exacerbate sway from the wind: thinned and supported with a pole (TP), thinned with an added sail (TS), thinned control (TC), and unthinned control (UC). Terminal leader growth, radial increment, and earlywood and latewood widths at breast height were measured for the last six growing seasons. The specific hydraulic conductivity of stems was measured. The results showed that thinning increased diameter growth and reduced height growth and slenderness coefficient (particularly for trees with added sails) compared with the unthinned control. Trees from thinned stands had reduced specific conductivity compared with the trees from unthinned controls, suggesting that tree bending caused functional damage to sapwood. Specific conductivity was 1.36 × 105, 1.06 × 105, 0.96 × 105, and 0.83 × 105 m·s1 in UC, TP, TC, and TS treatments, respectively. Trees from thinned stands, however, increased their total leaf area in the years following thinning.
Effects of streamside logging on stream macroinvertebrate communities and habitat in the sub-boreal forests of British Columbia, Canada
Authors: Fuchs Shirley A , Hinch Scott G , Mellina Eric
Published: August 2003

Much of the future timber supply in the Northern Hemisphere will come from boreal and sub-boreal forests, yet there has been little investigation of how aquatic communities in these regions would be affected by logging. We conducted an empirical, comparative study to investigate the effects of streamside clear-cut logging on benthic macroinvertebrates, algal standing stock, and in-stream physical and chemical habitats in the sub-boreal central interior region of British Columbia. We found that streams that flowed through old-growth forests (sites termed "not logged") did not differ from streams flowing through older logged forests (where the riparian zones were harvested 2025 years before our sampling; sites termed "older logged") with respect to macroinvertebrate total density or biomass, feeding guild density or biomass, and chlorophyll a biomass. However, streams flowing through newly logged forests (where the riparian zones were harvested within 5 years of our sampling; sites termed "recently logged") had nearly twice the macroinvertebrate biomass as those in not logged or older logged sites and higher chlorophyll a biomass. There were no differences among the three stream categories in regard to structural aspects of the physical habitat (e.g., substrate composition, large organic debris density, dimensions of pools and riffles). Streamside logging in sub-boreal forests appears to enhance primary and secondary production, but this phenomenon may only be evident for the first two decades following logging.
Progress towards understanding the structure, function, and ecological significance of small stream channels and their riparian zones
Authors: Moore R Dan , Richardson John S
Published: August 2003

Incomplete knowledge of the ecological functions of small streams and their riparian zones, particularly their roles in larger watershed and landscape contexts, contributes to confusion and debate about the levels of riparian vegetation retention required along small streams for the purpose of protecting aquatic ecosystems, riparian wildlife, and water quality. As a consequence, there are marked differences in riparian forestry practices and management among jurisdictions throughout North America. To aid in resolving these issues, a symposium on small streams and their riparian zones was held at The University of British Columbia from 19 to 21 February 2002, which brought together scientists, managers, and practitioners and provided a forum for the presentation and discussion of emerging research results. This special issue includes a selection of papers presented at that symposium as well as one solicited paper.
Amplitude and AVO responses of a single thin bed
Authors: Liu Yinbin , Schmitt Douglas R.
Published: August 2003

The seismic reflection characterizations of a thin layer are important for reservoir geophysics. However, discussions on the reflection for a thin layer are usually restricted to precritical angle incidence. In this work, an exact analytical solution is derived to model the reflection amplitude and amplitude variation with offset (AVO) responses of a single thin bed for arbitrary incident angles. The results show that the influence of an ultra‐thin bed is great for opposite‐polarity reflections and is small for identical‐polarity reflections. Opposite‐polarity precritical reflection amplitudes first decrease in magnitude with the wavelength/thickness ratio to a local minimum, then increase to a maximum, and finally decrease gradually to zero as the layer vanishes. Opposite‐polarity postcritical reflections monotonically decrease from near unity to zero, proportional to the thickness of the layer. Identical‐polarity precritical reflection amplitudes first increase in magnitude with the wavelength/thickness ratio to a local maximum, then decrease to a minimum, and finally increase to the amplitude of a single bottom reflection when the layer vanishes. Identical‐polarity postcritical reflections have magnitudes near unity. The AVO responses for both opposite and identical‐polarity acoustic thin beds gradually increase with angle. The influence of the Poisson's ratio of the thin bed is small for either small incidence angles or thicknesses less than 7% of the seismic wavelength, but is large for high incidence angles or thicknesses greater than 13% of the wavelength. A decrease of Poisson's ratio causes a pronounced AVO response that reaches its maximum at the quarter‐wavelength tuning thickness.
Illumination‐based normalization for wave‐equation depth migration
Authors: Rickett James E.
Published: August 2003

Illumination problems caused by finite‐recording aperture and lateral velocity lensing can bias amplitudes in migration results. In this paper, I develop a normalization scheme appropriate for wave‐equation migration algorithms that compensates for irregular illumination. I generate synthetic seismic data over a reference reflectivity model, using the adjoint of wave‐equation shot‐profile migration as the forward modeling operator. I then migrate the synthetic data with the same shot‐profile algorithm. The ratio between the synthetic migration result and the initial reference model is a measure of seismic illumination. Dividing the true data migration result by this illumination function mitigates the illumination problems. The methodology can take into account reflector dip as well as both shot and receiver geometries, and, because it is based on wave‐equation migration, it naturally models the finite‐frequency effects of wave propagation. The reference model should be as close to the true model as possible; good choices include the migrated image, or a synthetic image with a single known dip that corresponds to the expected dip of a reflector of interest. Computational shortcuts allow the illumination functions to be computed at about the cost of a single migration. Results indicate that normalization can significantly reduce amplitude distortions due to irregular subsurface illumination.
Estimating the distribution of primary reflection coefficients
Authors: Velis Danilo R.
Published: August 2003

The distribution of primary reflection coefficients can be estimated by means of the maximum entropy method, giving rise to smooth nonparametric functions which are consistent with the data. Instead of using classical moments (e.g. skewness and kurtosis) to constraint the maximization, nonconventional sample statistics help to improve the quality of the estimates. Results using real log data from various wells located in the Neuquen Basin (Argentina) show the effectiveness of the method to estimate both robust and consistent distributions that may be used to simulate realistic sequences.
Temperature and the expression of seven muscle-specific protein genes during embryogenesis in the Atlantic codGadus morhuaL.
Authors: Hall Thomas E. , Cole Nicholas J. , Johnston Ian A.
Published: August 2003

Seven cDNA clones coding for different muscle-specific proteins (MSPs) were isolated from the fast muscle tissue of Atlantic cod Gadus morhua L. In situ hybridization using cRNA probes was used to characterize the temporal and spatial patterns of gene expression with respect to somite stage in embryos incubated at 4°C, 7°C and 10°C. MyoDtranscripts were first observed in the presomitic mesoderm prior to somite formation, and in the lateral compartment of the forming somites. MyoD expression was not observed in the adaxial cells that give rise to the slow muscle layer, and expression was undetectable by in situhybridization in the lateral somitic mesoderm after the 35-somite stage,during development of the final ∼15 somites. RT-PCR analysis, however,confirmed the presence of low levels of the transcript during these later stages. A phylogenetic comparison of the deduced aminoacid sequences of the full-length MyoD cDNA clone and those from other teleosts, and inference from the in situ expression pattern suggested homology with a second paralogue (MyoD2) recently isolated from the gilthead seabream Sparus aurata. Following MyoD expression,α-actin was the first structural gene to be switched on at the 16-somite stage, followed by myosin heavy chain, troponin T, troponin I and muscle creatine kinase. The final mRNA in the series to be expressed was troponin C. All genes were switched on prior to myofibril assembly. The troponin C sequence was unusual in that it showed the greatest sequence identity with the rainbow trout Oncorhynchus mykiss cardiac/slow form, but was expressed in the fast myotomal muscle and not in the heart. In addition, the third TnC calcium binding site showed a lower level of sequence conservation than the rest of the sequence. No differences were seen in the timing of appearance or rate of posterior progression (relative to somite stage) of any MSP transcripts between embryos raised at the different temperatures. It was concluded that myofibrillar genes are activated asynchronously in a distinct temporal order prior to myofibrillar assembly and that this process was highly canalized over the temperature range studied.
Hepoxilins and trioxilins in barnacles: an analysis of their potential roles in egg hatching and larval settlement
Authors: Vogan Claire L. , Maskrey Ben H. , Taylor Graham W. , Henry Sheelagh , Pace-Asciak Cecil R. , Clare Anthony S. , Rowley Andrew F.
Published: August 2003

The barnacle life cycle has two key stages at which eicosanoids are believed to be involved in cellular communication pathways, namely the hatching of nauplii and the settlement of cypris larvae. Barnacle egg-hatching activity has previously been reported to reside in a variety of eicosanoids,including 8-hydroxyeicosapentaenoic acid and a number of tri-hydroxylated polyunsaturated fatty acid derivatives, the trioxilins. The production of the eicosapentaenoic acid metabolite trioxilin A4(8,11,12-trihydroxy-5,9,14,17-eicosatetraenoic acid) by the barnacles Balanus amphitrite and Elminius modestus was confirmed using a combination of high-performance liquid chromatography and gas chromatography, both linked to mass spectrometry. In addition, both species also generated trioxilin A3(8,11,12-trihydroxy-5,9,14-eicosatrienoic acid; an arachidonic acid-derived product), 8,11,12-trihydroxy-9,14,17-eicosatrienoic acid (a ω3 analogue of trioxilin A3; derived from ω3 arachidonic acid) and 10,13,14-trihydroxy-4,7,11,16,19-docosapentaenoic acid (a docosahexaenoic acid-derived product). In contrast to earlier reports, trioxilin A3had no E. modestus egg-hatching activity at any of the concentrations tested (10–9–10–6 mol l–1). The unstable epoxide precursor hepoxilin A3,however, caused significant levels of hatching at 10–6 mol l–1. Furthermore, the stable hepoxilin B3 analogue PBT-3 stimulated hatching at 10–7 mol l–1. Neither trioxilin A3, hepoxilin A3 or PBT-3 at 0.25–30 μmol l–1 served as settlement cues for B. amphitrite cypris larvae.
Recent Advances in Asymmetric CC and C‐Heteroatom Bond Forming Reactions using Polymer‐Bound Catalysts
Authors: Bräse Stefan , Lauterwasser Frank , Ziegert Robert E.
Published: August 2003

The synthesis of enantiomerically pure compounds is one of the major challenges in organic synthesis. In this review, we present the state of the art in asymmetric catalysis using immobilized chiral ligands and complexes for asymmetric CC and C‐heteroatom bond forming reactions. Chiral catalysts based on dendrimers and soluble polymeric supports are considered. In particular, addition reactions to carbon‐carbon double bonds, asymmetric 1,2‐addition reactions using, e.g., dialkylzinc reagents, metal‐catalyzed substitution reactions and cycloaddition reactions are covered. Specific emphasis is placed on enantioselective epoxidation and aldol reactions. A further aspect is the (hetero) Diels–Alder reaction catalyzed by immobilized ligands.
1‐Butyl‐3‐methylimidazolium Tetrafluoroborate ([Bmim]BF4) Ionic Liquid: A Novel and Recyclable Reaction Medium for the Synthesis of vic‐Diamines
Authors: Yadav J. S. , Reddy B. V. S. , Premalatha K.
Published: August 2003

Aziridines undergo ring opening smoothly with various arylamines in 1‐butyl‐3‐methylimidazolium tetrafluoroborate ([bmim]BF4) or 1‐butyl‐3‐methylimidazolium hexafluorophosphate ([bmim]PF6) ionic liquids under mild and neutral conditions to afford the corresponding vicinal‐diamines in excellent yields with high regioselectivity. The recovered activated ionic liquids are recycled for four to five runs with no loss of activity.
Suzuki–Miyaura Cross‐Coupling With Quasi‐Heterogeneous Palladium
Authors: Conlon David A. , Pipik Brenda , Ferdinand Simone , LeBlond Carl R. , Sowa John R. , Izzo Bill , Collins Paul , Ho Guo‐Jie , Williams J. Michael , Shi Yao‐Jun , Sun Yongkui
Published: August 2003

The Suzuki–Miyaura cross‐coupling reaction using heterogeneous Pd/C has a homogeneous component. The soluble palladium concentration increases during the reaction reaching a maximum at ca. 90% conversion before falling to <4 ppm.
Thin Layer Chromatography for the Detection of Unexpected Reactions in Organometallic Combinatorial Catalysis
Authors: Lavastre Olivier , Touzani Rachid , Garbacia Stefania
Published: August 2003

Thin layer chromatography (TLC) represents a fast and inexpensive alternative to NMR spectroscopy or analytical methods based on chromatography for the detection of unexpected products in organometallic combinatorial catalysis. This screening test led to the detection of the catalytic system [Ir(COD)Cl]2/PPh3 for isomerisation of diolefinic substrates instead the expected ring closing metathesis (RCM) reaction.
The Effect of Aromatic Ethers on the Trimerisation of Ethylene using a Chromium Catalyst and Aryloxy Ligands
Authors: Morgan David H. , Schwikkard Sianne L. , Dixon John T. , Nair Jerald J. , Hunter Roger
Published: August 2003

A catalyst system consisting of a chromium source, a 2,6‐disubstituted phenol and an aromatic ether solvent, on activation with triethylaluminium, is active and selective for the trimerisation of ethylene to form 1‐hexene. The aromatic ether appears to play a role as both solvent and reagent and is pivotal in ensuring both the good activity of the system as well as selectivity to the desired product, 1‐hexene.
Reactions of some phosphorus compounds with cellulose dissolved in aqueous alkaline solution
Authors: Petreuş Oana , Bubulac T. , Petreuş I. , Cazacu Georgeta
Published: August 2003

Dissolution of cellulose in aqueous hydroxide offers a procedure for regeneration of cotton or wood celluloses. The aqueous NaOH system for dissolving cellulose seems to have considerable potential for fiber production and also as a medium for preparing cellulose derivatives. Reactions with phosphoric and phosphorous acids, phenyl‐ and phenoxy phosphonic dichlorides, and an amido phosphite oligomer on aqueous dissolved cellulose are described. The resulting products are characterized by analytical and spectral methods (infrared and X‐ray diffraction) to determine phosphorus and nitrogen content, substitution degree, and polymerization degree. Particular attention was given to the effects produced by chemical modification on the crystalline pattern of microcrystalline cellulose. Some remarks are also made about the thermooxidative behavior of phosphorylated cellulose. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 327–333, 2003
Harmonic analysis in grease rheology
Authors: Karis Thomas E. , Kono Raymond‐Noël , Jhon Myung S.
Published: August 2003

Yield stress, and small‐ and large‐ amplitude oscillatory shear measurements were performed on greases in a cone‐plate fixture. Below the yield point, the grease behavior mimics that of a lightly crosslinked polymer. In large‐amplitude oscillations that exceed the yield stress, harmonic distortion appears in the stress waveform. The elastic component of the stress is continuous across the transition, while the viscous, or out‐of‐phase component, is a transient stress that occurs in the high shear rate portion of each oscillation cycle. Our newly proposed viscous slip model accurately reproduces the measured stress waveform for greases, as well as for other yield stress materials. From measured harmonic amplitudes, this model provides the strain amplitude dependence of the elastic modulus and the equivalent of a dynamic yield stress. These properties of channeling grease complement the conventional measurements of yield stress and worked and unworked penetration. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 334–343, 2003
Synthesis and characterization of oligo‐2‐hydroxy‐1‐naphthaldehyde and its Schiff base oligomers
Authors: Kaya İsmet , Şenol Dilek
Published: August 2003

In this study, oligo‐2‐hydroxy‐1‐naphthaldehyde (OHNA) was synthesized from the oxidative polycondensation of 2‐hydroxy‐1‐naphthaldehyde (HNA) with air oxygen, NaOCl, and H2O2 in an aqueous alkaline medium at 50–95°C. We determined the products and the oxidative polycondensation reaction conditions of HNA with oxidants such as air oxygen, NaOCl, and H2O2. In these reactions, H2O2 was more active than air oxygen and NaOCl and their optimum reaction conditions were studied. The products were characterized by 1H‐NMR, FTIR, UV–visible, and elemental analysis. The respective number‐average molecular weight, mass‐average molecular weight, and polydispersity index values of OHNA and its Schiff base oligomers (compounds 1, 2, and 3) were found to be 500 g mol−1, 1880 g mol−1, and 3.75 for OHNA; 670 g mol−1, 2490 g mol−1, and 3.71 for compound 1; 390 g mol−1, 1080 g mol−1, and 2.77 for compound 2; and 320 g mol−1, 670 g mol−1, and 1.85 for compound 3. At the optimum reaction conditions, the yields of the reaction products were found to be 77.0% O2, 78.0% H2O2, and 75.4% NaOCl. About 80% of the HNA was converted into OHNA. In addition, new Schiff based oligomers were synthesized from the condensation reaction of OHNA with p‐aminophenol, triethyleneglycol bis(4‐aminophenyl ether), and aniline and their structures and properties were determined. Thermogravimetric and dynamic thermal analyses showed OHNA and its Schiff base oligomers to be stable against thermooxidative decomposition. The weight losses of OHNA and its Schiff base oligomer compounds 1, 2, and 3 were found to be 5% at 175, 225, 190, and 230°C, respectively; 50% at 900, 590, 650, and 620°C, respectively; and 60, 80, 85, and 82%, respectively, at 1000°C. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 442–450, 2003
Structural effect of prepared and commercial superplasticizers on performance of cement pastes
Authors: Aiad I. , Hafiz A. A.
Published: August 2003

The sodium salt of melamine‐phenol formaldehyde sulfonate (MPhFS), melamine formaldehyde sulfonate (MFS), and phenol formaldehyde sulfonate (PhFS) were prepared according to a four‐step reaction procedure. The four steps of the reaction are hydroxymethylation, sulfonation, low pH condensation, and high pH rearrangement. Fourier transform IR and differential scanning calorimetry spectra were used to determine the structure of the synthesized resins. The effects of MFS, PhFS, MPhFS, and commercial superplasticizers on the rheological properties of cement pastes were investigated using a rotating coaxial viscometer. It was found that the prepared resins enhanced the rheological properties of cement pastes more than commercial ones. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 482–487, 2003
Short melamine fiber filled nitrile rubber composites
Authors: R. S. Rajeev , Bhowmick Anil K. , De S. K. , Bandyopadhyay S.
Published: August 2003

This article reports the development of a new composite based on acrylonitrile butadiene rubber (NBR) and melamine fiber. Atomic force microscopy (AFM) and scanning electron microscopy (SEM) have been used to study the effect of a dry bonding system in improving the adhesion between the fiber and the matrix. Mechanical properties of the composites are improved in the presence of the dry bonding system comprising of resorcinol, hexamethylene tetramine (hexamine), and hydrated silica. SEM and atomic force microscopic (AFM) images show that there are distinct changes in the fiber‐matrix interphase with the incorporation of the dry bonding system. A strong attachment of the fiber to the matrix is found in the SEM photomicrographs of the tensile fracture surfaces of the composites containing the dry bonding system. AFM section analysis and surface plot show that the improvement in tensile strength and modulus in the presence of the dry bonding system is due to the formation of a well‐defined interphase between the fiber and the matrix. The width of the interphase between the fiber and the matrix is increased in the presence of the dry bonding system, which is reflected in the mechanical properties and aging characteristics. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 544–558, 2003
Behavior of acrylic acid–itaconic acid hydrogels in swelling, shrinking, and uptakes of some metal ions from aqueous solution
Authors: Rodríguez Elena , Katime Issa
Published: August 2003

An experimental research of the absorption properties of metal ions onto synthetic hydrogel obtained by solution polymerization of acrylic acid and itaconic acid in presence of N,N′‐methylenebisacrylamide as crosslinking agent was carried out. The swelling behavior in aqueous salt solutions was studied as a function of divalent cation concentration (Cu2+, Zn2+, Ni2+, Co2+, Cd2+, Pb2+, Hg2+) in the external solution ranging from 10−5 to 1M, at 25°C. The ability of these hydrogels to bind cations was measured at different pH values and metal ion concentrations. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 530–536, 2003
Quality control in scholarly publishing: A new proposal
Authors: Mizzaro Stefano
Published: August 2003

The Internet has fostered a faster, more interactive and effective model of scholarly publishing. However, as the quantity of information available is constantly increasing, its quality is threatened, since the traditional quality control mechanism of peer review is often not used (e.g., in online repositories of preprints, and by people publishing whatever they want on their Web pages).

This paper describes a new kind of electronic scholarly journal, in which the standard submission‐review‐publication process is replaced by a more sophisticated approach, based on judgments expressed by the readers: in this way, each reader is, potentially, a peer reviewer. New ingredients, not found in similar approaches, are that each reader's judgment is weighted on the basis of the reader's skills as a reviewer, and that readers are encouraged to express correct judgments by a feedback mechanism that estimates their own quality. The new electronic scholarly journal is described in both intuitive and formal ways. Its effectiveness is tested by several laboratory experiments that simulate what might happen if the system were deployed and used.
Efficient Synthesis of 2‐Alkylidene‐3‐iminoindoles, Indolo[1,2‐b]isoquinolin‐5‐ones, δ‐Carbolines, and Indirubines by Domino and Sequential Reactions of Functionalized Nitriles
Authors: Langer Peter , Anders Joachim T. , Weisz Klaus , Jähnchen Judith
Published: August 2003

The sodium hydride mediated cyclization of arylacetonitriles with oxalic acid bis(imidoyl) dichlorides, aza‐analogues of oxalyl chloride, afforded functionalized 2‐alkylidene‐3‐iminoindoles with very good regio‐ and E/Z selectivity. Excellent chemoselectivities were observed for functionalized substrates. Based on these results a domino “cyclization–lactamization” reaction of bis(imidoyl) chlorides with methyl 2‐(cyanomethyl)benzoate was developed. This process allowed a convenient one‐pot synthesis of indolo[1,2‐b]isoquinolin‐5‐ones related to tryptanthrin. A new and convenient synthesis of δ‐carbolines by intramolecular electrocyclization–elimination reactions of 2‐alkylidene‐3‐iminoindoles was developed. It was shown that δ‐carbolines selectively bind to triplex or duplex DNA (intercalation). Indirubine analogues were prepared by deprotection and lactonization of functionalized 2‐alkylidene‐3‐iminoindoles.
Pluronic L61 Accelerates Flip–Flop and Transbilayer Doxorubicin Permeation
Authors: Krylova Oxana O. , Melik‐Nubarov Nikolay S. , Badun Gennadii A. , Ksenofontov Alexander L. , Menger Fred M. , Yaroslavov Alexander A.
Published: August 2003

It has recently been found that Pluronics (block copolymers of ethylene oxide, EO, and propylene oxide, PO) favor the permeability and accumulation of anthracycline antibiotics, for example doxorubicin (Dox), in tumor cells. In an effort to understand these results, the interaction of EO2/PO32/EO2 (Pluronic L61) with unilamellar egg yolk vesicles (80–100 nm in diameter) was examined. A partition coefficient Kp=[Pl]membrane/[Pl]water=45 was determined. This corresponds to adsorption of about 20 polymer molecules to the surface of each vesicle in a 20 μM polymer solution. Despite this rather weak adsorption, Pluronic has a substantial effect upon the transmembrane permeation rate of Dox and upon the phospholipid flip–flop rate within the bilayers. Thus, the Dox permeation rate increases threefold and the flip–flop rate increases sixfold in 20 μM Pluronic. The two rates increase linearly with the amount of adsorbed polymer. The obvious ability of Pluronics to increase the mobility of membrane components may have important biomedical consequences.