bluuebunny/crossref_metadata_2025 huggingface dataset:
On-beam synchrony in the cerebellum as the mechanism for the timing and coordination of movement
Authors: Heck D. H. , Thach W. T. , Keating J. G.
Published: April 2007

In trained reaching rats, we recorded simple spikes of pairs of Purkinje cells that, with respect to each other, were either aligned on a beam of shared parallel fibers or instead were located off beam. Rates of simple spike firing in both on-beam and off-beam Purkinje cell pairs commonly showed great variety in depth of modulation during reaching behavior. But with respect to timing, on-beam Purkinje cell pairs had simple spikes that were tightly time-locked to each other (either delayed or simultaneous) and to movement, despite the variability in rate. By contrast, off-beam Purkinje cell pairs had simple spikes that were not time-locked to each other, neither delayed nor simultaneous. We discuss the implications of these observations for the cerebellar role in timing and coordinating movement.
The
cidA
murein hydrolase regulator contributes to DNA release and biofilm development in
Staphylococcus aureus
Authors: Rice Kelly C. , Mann Ethan E. , Endres Jennifer L. , Weiss Elizabeth C. , Cassat James E. , Smeltzer Mark S. , Bayles Kenneth W.
Published: April 2007

The
Staphylococcus aureus cidA
and
lrgA
genes have been shown to affect cell lysis under a variety of conditions during planktonic growth. It is hypothesized that these genes encode holins and antiholins, respectively, and may serve as molecular control elements of bacterial cell lysis. To examine the biological role of cell death and lysis, we studied the impact of the
cidA
mutation on biofilm development. Interestingly, this mutation had a dramatic impact on biofilm morphology and adherence. The
cidA
mutant (KB1050) biofilm exhibited a rougher appearance compared with the parental strain (UAMS-1) and was less adherent. Propidium iodide staining revealed that KB1050 accumulated more dead cells within the biofilm population relative to UAMS-1, indicative of reduced cell lysis. In agreement with this finding, quantitative real-time PCR experiments demonstrated the presence of 5-fold less genomic DNA in the KB1050 biofilm relative to UAMS-1. Furthermore, treatment of the UAMS-1 biofilm with DNase I caused extensive cell detachment, whereas similar treatment of the KB1050 biofilm had only a modest effect. These results demonstrate that
cidA
-controlled cell lysis plays a significant role during biofilm development and that released genomic DNA is an important structural component of
S. aureus
biofilm.
Targeting the β-catenin/TCF transcriptional complex in the treatment of multiple myeloma
Authors: Sukhdeo Kumar , Mani Mala , Zhang Yunyu , Dutta Jui , Yasui Hiroshi , Rooney Melissa D. , Carrasco Daniel E. , Zheng Mei , He Haiying , Tai Yu-Tzu , Mitsiades Constantine , Anderson Kenneth C. , Carrasco Daniel R.
Published: April 2007

Multiple myeloma (MM) is an invariably fatal form of cancer characterized by clonal proliferation of malignant plasma cells in the bone marrow. The canonical Wnt signaling pathway is activated in MM cells through constitutively active β-catenin, a messenger molecule relevant to growth, survival, and migration of MM cells. The identification of a number of small molecular compounds, such as PKF115–584, which disrupt the interaction of the transcriptionally active β-catenin/TCF protein complex, provides valuable new therapeutic tools to target an alternative pathway in MM independent of the proteasome. Here we evaluated the transcriptional, proteomic, signaling changes, and biological sequelae associated with the inhibition of Wnt signaling in MM by PKF115–584. The compound blocks expression of Wnt target genes and induces cytotoxicity in both patient MM cells and MM cell lines without a significant effect in normal plasma cells. In xenograft models of human MM, PKF115–584 inhibits tumor growth and prolongs survival. Taken together, these data demonstrate the efficacy of disrupting the β-catenin/TCF transcriptional complex to exploit tumor dependence on Wnt signaling as a therapeutic approach in the treatment of MM.
An information-theoretic framework for resolving community structure in complex networks
Authors: Rosvall Martin , Bergstrom Carl T.
Published: April 2007

To understand the structure of a large-scale biological, social, or technological network, it can be helpful to decompose the network into smaller subunits or modules. In this article, we develop an information-theoretic foundation for the concept of modularity in networks. We identify the modules of which the network is composed by finding an optimal compression of its topology, capitalizing on regularities in its structure. We explain the advantages of this approach and illustrate them by partitioning a number of real-world and model networks.
Water surface is acidic
Authors: Buch Victoria , Milet Anne , Vácha Robert , Jungwirth Pavel , Devlin J. Paul
Published: April 2007

Water autoionization reaction 2H
2
O → H
3
O
−
+ OH
−
is a textbook process of basic importance, resulting in pH = 7 for pure water. However, pH of pure water surface is shown to be significantly lower, the reduction being caused by proton stabilization at the surface. The evidence presented here includes
ab initio
and classical molecular dynamics simulations of water slabs with solvated H
3
O
+
and OH
−
ions, density functional studies of (H
2
O)
48
H
+
clusters, and spectroscopic isotopic-exchange data for D
2
O substitutional impurities at the surface and in the interior of ice nanocrystals. Because H
3
O
+
does, but OH
−
does not, display preference for surface sites, the H
2
O surface is predicted to be acidic with pH < 4.8. For similar reasons, the strength of some weak acids, such as carbonic acid, is expected to increase at the surface. Enhanced surface acidity can have a significant impact on aqueous surface chemistry, e.g., in the atmosphere.
The limited impact of kinship on cooperation in wild chimpanzees
Authors: Langergraber Kevin E. , Mitani John C. , Vigilant Linda
Published: April 2007

The complex cooperative behavior exhibited by wild chimpanzees generates considerable theoretical and empirical interest, yet we know very little about the mechanisms responsible for its evolution. Here, we investigate the influence of kinship on the cooperative behavior of male chimpanzees living in an unusually large community at Ngogo in Kibale National Park, Uganda. Using long-term field observations and molecular genetic techniques to identify kin relations between individuals, we show that male chimpanzees clearly prefer to affiliate and cooperate with their maternal brothers in several behavioral contexts. Despite these results, additional analyses reveal that the impact of kinship is limited; paternal brothers do not selectively affiliate and cooperate, probably because they cannot be reliably recognized, and the majority of highly affiliative and cooperative dyads are actually unrelated or distantly related. These findings add to a growing body of research that indicates that animals cooperate with each other to obtain both direct and indirect fitness benefits and that complex cooperation can occur between kin and nonkin alike.
Increased frequencies of CD4+CD25high regulatory T cells in acute dengue infection
Authors: Lühn Kerstin , Simmons Cameron P. , Moran Edward , Dung Nguyen Thi Phuong , Chau Tran Nguyen Bich , Quyen Nguyen Than Ha , Thao Le Thi Thu , Van Ngoc Tran , Dung Nguyen Minh , Wills Bridget , Farrar Jeremy , McMichael Andrew J. , Dong Tao , Rowland-Jones Sarah
Published: April 2007

Dengue virus infection is an increasingly important tropical disease, causing 100 million cases each year. Symptoms range from mild febrile illness to severe hemorrhagic fever. The pathogenesis is incompletely understood, but immunopathology is thought to play a part, with antibody-dependent enhancement and massive immune activation of T cells and monocytes/macrophages leading to a disproportionate production of proinflammatory cytokines. We sought to investigate whether a defective population of regulatory T cells (T reg cells) could be contributing to immunopathology in severe dengue disease.

CD4+CD25highFoxP3+ T reg cells of patients with acute dengue infection of different severities showed a conventional phenotype. Unexpectedly, their capacity to suppress T cell proliferation and to secrete interleukin-10 was not altered. Moreover, T reg cells suppressed the production of vasoactive cytokines after dengue-specific stimulation. Furthermore, T reg cell frequencies and also T reg cell/effector T cell ratios were increased in patients with acute infection. A strong indication that a relative rise of T reg cell/effector T cell ratios is beneficial for disease outcome comes from patients with mild disease in which this ratio is significantly increased (P < 0.0001) in contrast to severe cases (P = 0.2145). We conclude that although T reg cells expand and function normally in acute dengue infection, their relative frequencies are insufficient to control the immunopathology of severe disease.
Entropy‐Based Model for Interpreting Life Systems in Traditional Chinese Medicine
Authors: Kang Guo-lian , Li Shao , Zhang Ji-feng
Published: April 2007

Traditional Chinese medicine (TCM) treats qi as the core of the human life systems. Starting with a hypothetical correlation between TCM qi and the entropy theory, we address in this article a holistic model for evaluating and unveiling the rule of TCM life systems. Several new concepts such as acquired life entropy (ALE), acquired life entropy flow (ALEF) and acquired life entropy production (ALEP) are propounded to interpret TCM life systems. Using the entropy theory, mathematical models are established for ALE, ALEF and ALEP, which reflect the evolution of life systems. Some criteria are given on physiological activities and pathological changes of the body in different stages of life. Moreover, a real data‐based simulation shows life entropies of the human body with different ages, Cold and Hot constitutions and in different seasons in North China are coincided with the manifestations of qi as well as the life evolution in TCM descriptions. Especially, based on the comparative and quantitative analysis, the entropy‐based model can nicely describe the evolution of life entropies in Cold and Hot individuals thereby fitting the Yin–Yang theory in TCM. Thus, this work establishes a novel approach to interpret the fundamental principles in TCM, and provides an alternative understanding for the complex life systems.
Aromatherapy Massage Affects Menopausal Symptoms in Korean Climacteric Women: A Pilot‐Controlled Clinical Trial
Authors: Hur Myung-Haeng , Yang Yun Seok , Lee Myeong Soo
Published: April 2007

This study investigated the effects of aromatherapy massage on menopausal symptoms in Korean climacteric women. Kupperman′s menopausal index was used to compare an experimental group of 25 climacteric women with a wait‐listed control group of 27 climacteric women. Aromatherapy was applied topically to subjects in the experimental group in the form of massage on the abdomen, back and arms using lavender, rose geranium, rose and jasmine in almond and primrose oils once a week for 8 weeks (eight times in total). The experimental group reported a significantly lower total menopausal index than wait‐listed controls (P < 0.05). There were also significant intergroup differences in subcategories such as vasomotor, melancholia, arthralgia and myalgia (all P < 0.05). These findings suggest that aromatherapy massage may be an effective treatment of menopausal symptoms such as hot flushes, depression and pain in climacteric women. However, it could not be verified whether the positive effects were from the aromatherapy, the massage or both. Further rigorous studies should be done with more objective measures.
Curcumin in Cell Death Processes: A Challenge for CAM of Age‐Related Pathologies
Authors: Salvioli S. , Sikora E. , Cooper E. L. , Franceschi C.
Published: April 2007

Curcumin, the yellow pigment from the rhizoma of Curcuma longa, is a widely studied phytochemical which has a variety of biological activities: anti‐inflammatory and anti‐oxidative. In this review we discuss the biological mechanisms and possible clinical effects of curcumin treatment on cancer therapy, and neurodegenerative diseases such as Alzheimer′s Disease, with particular attention to the cell death processes induced by curcumin. Since oxidative stress and inflammation are major determinants of the aging process, we also argue that curcumin can have a more general effect that slows down the rate of aging. Finally, the effects of curcumin can be described as xenohormetic, since it activates a sort of stress response in mammalian cells.
A simple algorithm locates β‐strands in the amyloid fibril core of α‐synuclein, Aβ, and tau using the amino acid sequence alone
Authors: Zibaee Shahin , Makin O. Sumner , Goedert Michel , Serpell Louise C.
Published: April 2007

Fibrillar inclusions are a characteristic feature of the neuropathology found in the α‐synucleinopathies such as Parkinson's disease, dementia with Lewy bodies, and multiple system atrophy. Familial forms of α‐synucleinopathies have also been linked with missense mutations or gene multiplications that result in higher protein expression levels. In order to form these fibrils, the protein, α‐synuclein (α‐syn), must undergo a process of self‐assembly in which its native state is converted from a disordered conformer into a β‐sheet‐dominated form. Here, we have developed a novel polypeptide property calculator to locate and quantify relative propensities for β‐strand structure in the sequence of α‐syn. The output of the algorithm, in the form of a simple x‐y plot, was found to correlate very well with the location of the β‐sheet core in α‐syn fibrils. In particular, the plot features three peaks, the largest of which is completely absent for the nonfibrillogenic protein, β‐syn. We also report similar significant correlations for the Alzheimer's disease‐related proteins, Aβ and tau. A substantial region of α‐syn is also of converting from its disordered conformation into a long amphipathic α‐helical protein. We have developed the aforementioned algorithm to locate and quantify the α‐helical hydrophobic moment in the amino acid sequence of α‐syn. As before, the output of the algorithm, in the form of a simple x‐y plot, was found to correlate very well with the location of α‐helical structure in membrane bilayer‐associated α‐syn.
Inter‐ring communication allows the GroEL chaperonin complex to distinguish between different substrates
Authors: van Duijn Esther , Heck Albert J.R. , van der Vies Saskia M.
Published: April 2007

The productive folding of substrate proteins by the GroEL complex of Escherichia coli requires the activity of both the chaperonin rings. These heptameric rings were shown to regulate the chaperonins' affinity for substrates and co‐chaperonin via inter‐ring communications; however, the molecular details of the interactions are not well understood. We have investigated the effect of substrate binding on inter‐ring communications of the chaperonin complex, both the double‐ring GroEL as well as the single‐ring SR1 chaperonin in complex with four different substrates by using mass spectrometry. This approach shows that whereas SR1 is unable to distinguish between Rubisco, gp23, gp5, and MDH, GroEL shows clear differences upon binding these substrates. The most distinctive binding behavior is observed for Rubisco, which only occupies one GroEL ring. Both bacteriophage capsid proteins (gp23 and gp5) as well as MDH are able to bind to the two GroEL rings simultaneously. Our data suggest that inter‐ring communication allows the chaperonin complex to differentiate between substrates. Using collision induced dissociation in the gas phase, differences between the chaperonin(substrate) complexes are observed only when both rings are present. The data indicate that the size of the substrate is an important factor that determines the degree of stabilization of the chaperonin complex.
Breeding bird species richness in Spain: assessing diversity hypothesis at various scales
Authors: González‐Taboada Fernando , Nores Carlos , Ángel Álvarez Miguel
Published: April 2007

The variation of passerine species richness in Spain was studied at various spatial scales. Presence‐absence data was resampled to construct three species richness maps in lattices of 10×10, 30×30, and 50×50 km UTM cells. The importance of habitat, species‐energy, climatic variability, disturbance, history and geometric constraints hypotheses was assessed using geographical data. Stochastic, range‐based models were used to simulate neutral colonization events from Europe or from Africa. The importance of small scale processes remained after the inclusion of environmental covariates, indicating a possible role of ecological interactions that was represented in the models by a conditional spatial autoregressive term. Historical effects and energy related measures explained most of the variation in regional species richness. Local and regional habitat structure measures explained the pattern only after large scale trends were considered. The differences when species richness was analyzed at each scale reveal the importance of spatial issues in diversity studies. The possible role of post glacial migration in shaping the observed patterns, and implications for conservation are discussed.
The importance of sward architectural complexity in structuring predatory and phytophagous invertebrate assemblages
Authors: WOODCOCK B. A. , POTTS S. G. , WESTBURY D. B. , RAMSAY A. J. , LAMBERT M. , HARRIS S. J. , BROWN V. K.
Published: April 2007

Abstract 1. Although the importance of plant community assemblages in structuring invertebrate assemblages is well known, the role that architectural complexity plays is less well understood. In particular, direct empirical data for a range of invertebrate taxa showing how functional groups respond to plant architecture is largely absent from the literature.

2. The significance of sward architectural complexity in determining the species richness of predatory and phytophagous functional groups of spiders, beetles, and true bugs, sampled from 135 field margin plots over 2 years was tested. The present study compares the relative importance of sward architectural complexity to that of plant community assemblage.

3. Sward architectural complexity was found to be a determinant of species richness for all phytophagous and predatory functional groups. When individual species responses were investigated, 62.5% of the spider and beetle species, and 50.0% of the true bugs responded to sward architectural complexity.

4. Interactions between sward architectural complexity and plant community assemblage indicate that the number of invertebrate species supported by the plant community alone could be increased by modification of sward architecture. Management practices could therefore play a key role in diversifying the architectural structure of existing floral assemblages for the benefit of invertebrate assemblages.

5. The contrasting effects of sward architecture on invertebrate functional groups characterised by either direct (phytophagous species) or indirect (predatory species) dependence on plant communities is discussed. It is suggested that for phytophagous taxa, plant community assemblage alone is likely to be insufficient to ensure successful species colonisation or persistence without appropriate development of sward architecture.
Theoretical perspectives of nursing: a review of the literature
Authors: Hilton Penelope Ann
Published: April 2007

The discipline of nursing has slowly evolved from the traditional role of women having been influenced by a variety of factors such as apprenticeship, humanitarian aims, religious ideals, medicine, increasing technology, politics, war, feminism and more recently research. This variety of influences is reflected in the many and varied definitions and descriptions of nursing currently espoused in the literature. A review of the most widely cited definitions and descriptions of nursing from Nightingale to the present day resulted in the identification of eight theoretical perspectives of nursing. Each of these are discussed. The author concludes that nursing has yet to arrive at a consensus regarding the nature, components and process of nursing which is crucial for professional credibility and the viability of professional nursing as it enters the next millennium.
A controlled clinical trial of implant‐retained mandibular overdentures: clinical aspects
Authors: BOERRIGTER E.M. , VAN OORT R.P. , RAGHOEBAR G. M. , STEGENGA B. , SCHOEN P.J. , BOERING G.
Published: April 2007

summary
In a controlled clinical trial, treatment effects of mandibular overdentures on two different implant‐systems in edentulous patients were compared one year after insertion of the new dentures. The implant‐systems used were the Brånemark system (Brå) and the IMZ‐system. Treatment was randomly assigned to 60 patients according to a balanced allocation method. Evaluation included peri‐implant and radiographical parameters. According to the Delphi method a clinical implant performance scale (CIP) was constructed based on all conceivable complications of the different implant systems. During the osseointegration period, five Brå‐ and one IMZ‐implants were lost. The results of one of the peri‐implant parameters and the radiographical score showed significant differences considering the (pseudo) pocket probing depth (Brå better than IMZ, P< 0.001) and the radiographic‐score (IMZ better than Brå, P < 0003). The results for the CIP‐scale were less favourable for the Brå‐group than for the IMZ‐group; however, these differences were not significant.
An in vitro microleakage study of the ‘bonded‐base’ restorative technique
Authors: YAP A. U. J. , MOK B. Y. Y. , PEARSON G.
Published: April 2007

summary
Microleakage associated with a silver‐reinforced restorative glass–ionomer cement (Hi‐Dense) used with a composite resin (Z100) in a modified Class II bonded‐base technique restoration was evaluated. The influence of long‐term artificial saliva storage, thermal and load cycling was also determined. Class II composite (Z100) restorations used with a new dental adhesive system (Scotchbond Multi‐Purpose Dental Adhesive®) were used as controls. Results showed that the bonded‐base technique can reduce the leakage observed with the direct composite technique. Thermocycling decreased the leakage at the composite–enamel interface but had no effect on the leakage at the composite–dentine interface or on the leakage patterns of bonded‐base restorations. Load cycling had no significant influence on leakage patterns of either type of restorative mode. Storage in artificial saliva resulted in decreased leakage at the composite‐enamel interface but had a minor adverse effect at the glass–ionomer–dentine interface.
Comparison of muscle activity and occlusal contacts during maximal and habitual clenching in varied chair positions
Authors: KIM Y.K. , LEE S.W. , CHUNG S.C. , KHO H.S.
Published: April 2007

summary
The activity of anterior temporal muscle, the number of tooth contacts, and total duration of closure during maximal and habitual clenching were studied in varied chair positions. Fifteen subjects were evaluated. The means for the muscle activity of anterior temporal muscle during habitual clenching were 63.5–73.5% of maximum muscle activity. The number of tooth contacts and total duration of closure were significantly increased as biting pressure was increased from habitual to maximal clenching. No significant differences were detected in all variables among varied chair positions. The above results also suggested that occlusal instability was very common. Further research is required to explain the relationship, if any, of these variables to craniomandibular disorders.
In vitro effects of alcohol‐containing and alcohol‐free mouthrinses on microhardness of some restorative materials
Authors: GÜRGAN S. , ÖNEN A. , KÖPRÜLÜ H.
Published: April 2007

summary
Daily application of mouthrinses has been recommended for the prevention and control of caries and periodontal disease. The aim of this study was to evaluate the effect of alcohol‐containing and alcohol‐free mouthrinses on the microhardness of three restorative materials. Materials tested included visible light cured (VLC) composite resin (Amelogen), VLC glass–ionomer cement (Fuji II LC) and a fissure sealant (Ultra Seal XT). Eighteen cylinders of each restorative were fabricated and initially stored in distilled water for 24 h. Six samples of the restoratives were stored for 12 hours to simulate a 2 min/day for 1 year exposure to mouthrinses in the following solutions: distilled water (control), alcohol‐containing mouthrinse (Viadent) and alcohol‐free mouthrinse (Rembrandt). At the end of the test period microhardness was measured with a Tukon microhardness tester. Kruskal–Wallis one‐way analysis of variance was used to analyse the data. Both mouthrinses affected the hardness of the materials tested.
Condylar asymmetry measurements in patients with an Angle's Class III malocclusion
Authors: MILLER V.J. , BODNER L.
Published: April 2007

summary
Condylar asymmetry/age relationships were investigated in a group of 23 dentate patients with an Angle's Class III malocclusion and no signs or symptoms of temporomandibular disorders and no prior orthodontic treatment. Condylar asymmetry was determined from panoramic radiographs. A graph of age versus asymmetry index was then plotted. There was no significant correlation between age and the asymmetry index in these patients (R2= 0.019). This is similar to results obtained for a group of patients with a Class I occlusion who were included as controls, and similar to a group of patients with an Angle's Class II division 2 malocclusion investigated previously.
Indirect genetic effects from ecological interactions in Arabidopsis thaliana
Authors: MUTIC JOSHUA J. , WOLF JASON B.
Published: April 2007

Indirect genetic effects arise when genes expressed in one individual affect the expression of traits in other individuals. The importance of indirect genetic effects has been recognized for a diversity of evolutionary processes including kin selection, sexual selection, community structure and multilevel selection, but data regarding their genetic architecture and prevalence throughout the genome remain scarce, especially for interactions between unrelated individuals. Using a set of 411 Bay‐0 × Shahdara Arabidopsis recombinant inbred lines grown with Landsberg neighbours, we examined quantitative trait loci (QTL) having direct and indirect effects on size, developmental, and fitness related traits. Using an interval mapping approach, we identified 15 QTL with direct effects and found that 13 of these QTL had significant indirect effects on trait expression in neighbouring plants. These results suggest widespread pleiotropy, as nearly all direct effect QTL have associated pleiotropic indirect effects. Paradoxically, most indirect effects were of the same sign as direct effects, creating a pattern of nearly universal positive pleiotropy that makes most covariances between direct and indirect effects positive. These results are consistent with a complex genetic basis for intraspecific interactions, but suggest that interactions between neighbouring plants are largely positive, rather than negative as would be expected for competition. In addition to their evolutionary and ecological importance, these pleiotropic relationships between DGE and IGE loci have implications for quantitative genetic studies of natural populations as well as experimental design considerations. Additionally, studies that ignore IGEs may over‐ or underestimate quantitative genetic parameters, as well as the effect of and variance contributed by QTL.
Genetic heterogeneity among intertidal habitats in the flat periwinkle, Littorina obtusata
Authors: SCHMIDT PAUL S. , PHIFER‐RIXEY MEGAN , TAYLOR GRAEME M. , CHRISTNER JOHN
Published: April 2007

Comparisons among patterns exhibited by functionally distinct genetic markers have been widely used to infer the impacts of demography and selection in structuring genetic variation in natural populations. However, such multilocus comparisons remain an indirect evaluation of selection at particular candidate loci; ideally, the identification of a candidate gene by comparative genetic methodologies should be complemented by functional analyses and experimental manipulations of genotypes in the laboratory or field. We examined genotype frequency variation among replicated intertidal habitats at two spatial scales in the grazing snail Littorina obtusata. Both of the candidate allozyme markers varied predictably with environment, and these patterns were consistent at both spatial scales. Three of four reference loci were spatially homogeneous, but one microsatellite exhibited significant structure at both geographical and mesoscales. To initiate a direct examination of whether the observed genotype frequency variation at one of the candidate markers, mannose‐6‐phosphate isomerase (MPI), was impacted by differential survivorship of genotypes, we conducted a series of laboratory‐based thermal stress assays using snails from two geographically disparate source populations. When snails were exposed to bouts of thermal/desiccation stress, patterns of mortality were nonrandom with respect to MPI genotype. Furthermore, patterns of mortality in the laboratory manipulation coincided with the observed distribution of genotypes in the field. The data suggest the operation of selection at the Mpi or a linked locus, but functional studies and further experimentation are required to establish the relationship between MPI genotype and fitness across heterogeneous intertidal environments.
The genetic basis of adaptive pigmentation variation in Drosophila melanogaster
Authors: POOL JOHN E. , AQUADRO CHARLES F.
Published: April 2007

In a broad survey of Drosophila melanogaster population samples, levels of abdominal pigmentation were found to be highly variable and geographically differentiated. A strong positive correlation was found between dark pigmentation and high altitude, suggesting adaptation to specific environments. DNA sequence polymorphism at the candidate gene ebony revealed a clear association with the pigmentation of homozygous third chromosome lines. The darkest lines sequenced had nearly identical haplotypes spanning 14.5 kb upstream of the protein‐coding exons of ebony. Thus, natural selection may have elevated the frequency of an allele that confers dark abdominal pigmentation by influencing the regulation of ebony.
Self‐compatibility in Brassica napus is caused by independent mutations in S‐locus genes
Authors: Okamoto Shunsuke , Odashima Masashi , Fujimoto Ryo , Sato Yutaka , Kitashiba Hiroyasu , Nishio Takeshi
Published: April 2007

Brassica napus is an amphidiploid species with the A genome from Brassica rapa and the C genome from Brassica oleracea. Although B. rapa, B. oleracea and artificially synthesized amphidiploids with the AC genome are self‐incompatible, B. napus is self‐compatible. Six S genotypes were identified in B. napus, five of which had class I S haplotypes from one species and a class II S haplotype from the other species, and mutations causing self‐compatibility were identified in three of these S genotypes. The most predominant S genotype (BnS‐1;BnS‐6), which is that of cv. ‘Westar’, had a class I S haplotype similar to B. rapa S‐47 (BrS‐47) and a class II S haplotype similar to B. oleracea S‐15 (BoS‐15). The stigmas of ‘Westar’ rejected the pollen grains of both BrS‐47 and BoS‐15, while reciprocal crossings were compatible. Insertion of a DNA fragment of about 3.6 kb was found in the promoter region of the SP11/SCR allele of BnS‐1, and transcripts of SP11/SCR were not detected in ‘Westar’. The nucleotide sequence of the SP11 genomic DNA of BnS‐6 was 100% identical to that of SP11 of BoS‐15. Class I SP11 alleles from one species showed dominance over class II SP11 alleles from the other species in artificially synthesized B. napus lines, suggesting that the non‐functional dominant SP11 allele suppressed the expression of the recessive SP11 allele in ‘Westar’. Two other S genotypes in B. napus also had non‐functional class I S haplotypes together with recessive BnS‐6. These observations suggest independent origins of self‐compatibility in B. napus.
Altered expression of plant lysyl tRNA synthetase promotes tRNA misacylation and translational recoding of lysine
Authors: Wu Xing Rong , Kenzior Alexander , Willmot David , Scanlon Sarah , Chen Zhihong , Topin Andrey , He Shao Hua , Acevedo Ashley , Folk William R.
Published: April 2007

The Arabidopsis thaliana lysyl tRNA synthetase (AtKRS) structurally and functionally resembles the well‐characterized prokaryotic class IIb KRS, including the propensity to aminoacylate tRNALys with suboptimal identity elements, as well as non‐cognate tRNAs. Transient expression of AtKRS in carrot cells promotes aminoacylation of such tRNAs in vivo and translational recoding of lysine at nonsense codons. Stable expression of AtKRS in Zea mays causes translational recoding of lysine into zeins, significantly enriching the lysine content of grain.
Sulfite oxidase protects plants against sulfur dioxide toxicity
Authors: Brychkova Galina , Xia Zongliang , Yang Guohua , Yesbergenova Zhazira , Zhang Zhili , Davydov Olga , Fluhr Robert , Sagi Moshe
Published: April 2007

The gaseous pollutant SO2 readily reacts with water to form sulfite that impacts deleteriously on animal and plant health. By modulating the level of sulfite oxidase (SO) that catalyzes the transformation of sulfites to the non‐toxic sulfate, we show that Arabidopsis and tomato plants can be rendered resistant or susceptible to SO2/sulfite. Plants in which sulfite oxidase expression was abrogated by RNA interference (RNAi) accumulated relatively less sulfate after SO2 application and showed enhanced induction of senescence and wounding‐associated transcripts, leaf necrosis and chlorophyll bleaching. In contrast, SO overexpression lines accumulated relatively more sulfate and showed little or no necrosis after SO2 application. The transcript of sulfite reductase, a chloroplast‐localized enzyme that reduces sulfites to sulfides, was shown to be rapidly induced by SO2 in a sulfite oxidase‐dependent manner. Transcripts of other sulfite‐requiring enzymatic activities such as mercaptopyruvate sulfur transferases and UDP‐sulfoquinovose synthase 1 were induced later and to a lesser extent, whereas SO was constitutively expressed and was not significantly induced by SO2. The results imply that plants can utilize sulfite oxidase in a sulfite oxidative pathway to cope with sulfite overflow.
From seedling to mature plant: Arabidopsis plastidial genome copy number, RNA accumulation and transcription are differentially regulated during leaf development
Authors: Zoschke Reimo , Liere Karsten , Börner Thomas
Published: April 2007

Little is known about DNA and RNA metabolism during leaf development and aging in the model organism Arabidopsis. Therefore we examined the nuclear and plastidial DNA content of tissue ranging in age from 2‐day‐old cotyledons to 37‐day‐old senescent rosette leaves. Flow‐cytometric analysis showed an increase in nuclear DNA ploidy levels of up to 128 genome copies per nucleus in older leaves. The copy numbers of nuclear 18S‐rRNA genes were determined to be 700 ± 60 per haploid genome. Adjusted to the average level of nuclear DNA polyploidism per cell, plastome copy numbers varied from about 1000 to 1700 per cell without significant variation during development from young to old rosette leaves. The transcription activity of all studied plastid genes was significantly reduced in older rosette leaves in comparison to that in young leaves. In contrast, levels of plastidial transcript accumulation showed different patterns. In the case of psbA, transcripts accumulated to even higher levels in older leaves, indicating that differential regulation of plastidial gene expression occurs during leaf development. Examination of promoter activity from clpP and rrn16 genes by primer extension analyses revealed that two RNA polymerases (NEP and PEP) transcribe these genes in cotyledons as well as in young and senescent leaves. However, PEP may have a more prominent role in older rosette leaves than in young cotyledons. We conclude that in cotyledons or leaves of different ages plastidial gene expression is regulated at the transcriptional and post‐transcriptional levels, but not by plastome copy number.
Arabidopsis thaliana plants possess a specific farnesylcysteine lyase that is involved in detoxification and recycling of farnesylcysteine
Authors: Crowell Dring N. , Huizinga David H. , Deem Angela K. , Trobaugh Corey , Denton Ryan , Sen Stephanie E.
Published: April 2007

In plants, prenylated proteins are involved in actin organization, calcium‐mediated signal transduction, and many other biological processes. Arabidopsis thaliana mutants lacking functional protein prenyltransferase genes have also revealed roles for prenylated proteins in phytohormone signaling and meristem development. However, to date, the turnover of prenylated plant proteins and the fate of the prenylcysteine (PC) residue have not been described. We have detected an enzyme activity in Arabidopsis plants that metabolizes farnesylcysteine (FC) to farnesal, which is subsequently reduced to farnesol. Unlike its mammalian ortholog, Arabidopsis FC lyase exhibits specificity for FC over geranylgeranylcysteine (GGC), and recognizes N‐acetyl‐FC (AFC). FC lyase is encoded by a gene on chromosome 5 of the Arabidopsis genome (FCLY, At5g63910) and is ubiquitously expressed in Arabidopsis tissues and organs. Furthermore, T‐DNA insertions into the FCLY gene cause significant decreases in FC lyase activity and an enhanced response to abscisic acid (ABA) in seed germination assays. The effects of FCLY mutations on ABA sensitivity are even greater in the presence of exogenous FC. These data suggest that plants possess a specific FC detoxification and recycling pathway.
Prey Size Selection under Simultaneous Choice by the Broad‐Headed Skink (Eumeces laticeps)
Authors: Cooper William E. , Anderson Roger A. , Frederick William G.
Published: April 2007

Diet selection among several prey types present in a dense aggregation, permitting a predator to become satiated without changing patches, may be important for predators that can eat many small prey items in a single bout. Choice in this scenario differs from that in optimal foraging models for sequential diet choice model and simultaneous choice models when travel time between patches is needed. Furthermore, satiation and depletion effects may be important in dense prey aggregations. We predicted that in dense prey aggregations, predators should eat the most profitable prey first, switching to smaller prey as larger ones become depleted and predators become satiated, and that prey below some minimum profitability should be rejected. When large numbers of prey of varying sizes were presented simultaneously, broad‐headed skinks (Eumeces laticeps) preferentially consumed large crickets, ate some medium‐sized crickets late in ingestion sequences, but ate no small crickets. Prey depletion, with selection of the currently most profitable prey type, appears to account for much of observed prey switching, and satiation may contribute. When four crickets of each of four sizes were presented, lizards ate largest first, then medium‐sized. Some then ate small crickets, but none ate very small crickets. These observations and exclusion of small crickets from the diet by many lizards when larger ones were unavailable support the predictions. In tests with three sizes of juvenile mice presented singly, the smallest were attacked at shortest latency and eaten, medium‐sized mice were attacked at greater latency but could not be subdued, and large mice were not attacked. These data suggest that as prey become too large to subdue and eat readily, profitability declines until they are excluded from the diet. Unsuccessful attacks on medium‐sized mice suggest that lizards had to learn their own capabilities with respect to a novel prey type.
Geographic Variation in the Long Calls of Male Orangutans (Pongo spp.)
Authors: Delgado Roberto A.
Published: April 2007

Relatively few data exist on population differences in the vocal behavior of mammals. Geographic variation in calls is of special interest because of the implications for resolving evolutionary and behavioral questions. For example, information on geographic variation in vocalizations complements morphological and molecular data used to infer phylogenetic relationships and provides evidence for the mechanisms underlying call development. A quantitative acoustic analysis of orangutan long calls was undertaken, comparing flanged adult males from four geographically distinct sites across Borneo and Sumatra, revealing consistent differences among the calls of individuals. Long calls produced by orangutans from the four sites in Borneo and Sumatra differ in quantitative acoustic measures. Discriminant function analysis reveals that acoustic variables can be used in combination to assign calls to the correct individual, site and island at rates higher than that expected by chance. Specifically, four acoustic parameters proved reliable for distinguishing among the individuals, between sites, and across the two islands that arguably represent populations from separate species or subspecies. Although Bornean and Sumatran long calls share a repetitive structure and show similar call rates (0.100–0.500 LCs/h) and maximum frequency bands (0.400–1.500 kHz), they differ significantly in the number of pulses per call, call speed, call duration, bandwidth, pulse duration, and dominant frequency. Strong consistency in these acoustic parameters is also seen among males within sites and the observed variation may allow for individual recognition. Individual identification by call structure presumably benefits dispersed orangutans, where individuals characteristically forage independently and both encounters and interactions with signaling males are highly variable and largely dependent on context. Acoustic recognition of callers facilitates the choice of which males to join or avoid, thus allowing receivers to manipulate potential costs and benefits of association.
Female Meadow Voles, Microtus pennsylvanicus, Experience a Reduction in Copulatory Behavior During Postpartum Estrus
Authors: DelBarco‐Trillo Javier , Ferkin Michael H.
Published: April 2007

In many small mammalian species, females undergo postpartum estrus (PPE), mate, and become pregnant soon after delivering a litter. Mating during PPE implies a trade‐off between attending to the new litter and leaving that litter to mate. We tested the hypothesis that copulatory behavior is faster when a female mates during PPE than when it mates outside of PPE, during male‐induced estrus (MIE), a time when it is not lactating. We compared several variables of copulatory behavior in female meadow vole mating during both PPE and MIE. Females in PPE received significantly fewer intromissions, with shorter intervals between intromissions. Each ejaculatory series was also shorter for females in PPE. As a consequence, the total amount of time devoted to copulation was much shorter for females in PPE than for those in MIE. These data support the hypothesis that female meadow voles are able to reduce their copulatory behavior during PPE.
The Payoff of Fighting in House Crickets: Motivational Asymmetry Increases Male Aggression and Mating Success
Authors: Brown William D. , Chimenti Andrew J. , Siebert Joseph R.
Published: April 2007

Motivational asymmetry caused by differences in subjective resource value is a key component of strategic models of aggression. We study the role of motivational asymmetry in determining differential aggression and mating success of male house crickets,Acheta domesticus. We also assess the extent to which mating differences associated with motivational asymmetry are due to direct male–male fighting vs. male–female interactions. We manipulated male motivation to compete for a mating opportunity by providing males with either no access or nightly access to females for 4 d prior to the experiment. As predicted, when males from each treatment had to compete for the female, those with lower prior access were more aggressive and mated more often. In contrast, when males from each treatment were paired individually with females, there was no significant difference in the frequencies with which they pursued, courted or mated with females. We also found no evidence for female choice based on motivational asymmetry; the rate of successful courtship did not differ between treatments. We conclude that prior mate encounter rate can generate motivational asymmetry, leading to differential mating success mediated by direct male–male aggression.
Phylogenetic study of benthic, spine‐bearing prorocentroids, including Prorocentrum fukuyoi sp. nov.
Authors: Murray Shauna , Nagahama Yukio , Fukuyo Yasuwo
Published: April 2007

Species of prorocentroid dinoflagellates are common in marine benthic sediment and epibenthic habitats, as well as in planktonic habitats. Marine planktonic prorocentroids typically possess a small spine in the apical region. In this study, we describe a new, potentially widely distributed benthic species of Prorocentrum, P. fukuyoi sp. nov., from tidal sand habitats in several sites in Australia and from central Japan. This species was found to possess an apical spine or flange and was sister species to P. emarginatum. We analyzed the phylogeny of the group including this new species, based on large subunit (LSU) rDNA sequences. The genus contained a high level of divergence in LSU rDNA, in some cases among sister taxa. P. fukuyoi and P. emarginatum were found to be most closely related to a clade of generally planktonic taxa. Several morphological features may constitute more informative synapomorphies than habitat in distinguishing clades of prorocentroid species.
Seasonal variations in thalli and carrageenan composition of Gigartina pistillata (Gmelin) Stackhouse (Rhodophyta, Gigartinales) harvested along the Atlantic coast of Morocco
Authors: Amimi Abdellah , Mouradi Aziza , Bennasser Laila , Givernaud Thiery
Published: April 2007

The biology and biochemistry of Gigartina pistillata (Gmelin) Stackhouse collected monthly at Nation Beach (Morocco), was studied during one year. The biological study showed one period of active growth from April to July. The thallus composition was quite stable during the major part of the year. The dry matter was maximum in May and August and minimum in January. The maximum carrageenan content occurred in June and September (about 37%) and the minimum carrageenan content occurred in February (19.0%). The total nitrogen content varied significantly, with a maximum in January (1.98%) and a minimum in August (0.7%). The ash content was significant (23–32%) with a maximum in August and a minimum in May. The carrageenan extracted from natural populations of Gigartina pistillata was a mixture of lambda‐type and kappa‐type carrageenans. The 3,6‐anhydrogalactose varied between 4.5 mol% in June to 25 mol% in February. For industrial applications the extract could be considered as a lambda‐type. The best period for harvest of G. pistillata in Morocco is between July and August when biomass and viscosity are at their maximum. A relationship between the physical characteristics of G. pistillata carrageenans and its seasonal cycle was deduced.