bluuebunny/crossref_metadata_2025 huggingface dataset:
Pregnancy and lactation modulate maternal splenic growth and development of the erythroid lineage in the rat and mouse
Authors: Bustamante Juan J. , Dai Guoli , Soares Michael J.
Published: January 2008

Maternal physiology changes dramatically during the course of gestation and lactation to meet the needs of the developing fetus and newborn. In the present study, we examined the influence of pregnancy and lactation on growth and erythroid gene expression patterns of the maternal spleen. Holtzman Sprague-Dawley rats and CD-1 mice were killed at various stages of gestation and post partum. We observed pregnancy dependent increases in spleen weight and spleen DNA content in both the rat and mouse. In the rat, spleen size was greatest at the end of pregnancy and regressed post partum. In contrast, mouse spleen size peaked by gestational Day 13 and regressed to its non-pregnant weight before parturition. Pregnancy dependent changes in the size of the spleen were primarily due to an increase in red pulp. Maternal spleen expression of erythroid-associated genes (erythroid Krüppel-like factor, erythroid 5-aminolevulinate synthase-2, β-major globin) was influenced by pregnancy and lactation. A pregnancy dependent increase in erythroid progenitors was also observed. In summary, the demands of pregnancy and lactation cause marked adaptations in the maternal spleen. The maternal spleen increases in size and exhibits an expansion of the erythroid lineage.
Reactive oxygen species and anti-oxidant defences in swine follicular fluids
Authors: Basini Giuseppina , Simona Bussolati , Santini Sujen Eleonora , Grasselli Francesca
Published: January 2008

A growing body of evidence indicates that the pro-oxidant/anti-oxidant balance inside the ovarian follicle plays an important role in folliculogenesis. Therefore, the aim of the present study was to assess the redox status of follicular fluids collected from different-sized swine follicles. We quantified the most important reactive oxygen species (ROS), namely superoxide anion (O2–), hydrogen peroxide and hydroperoxides (ROOH); in addition, we examined the activity of the detoxifying enzymes superoxide dismutase, catalase (CAT) and glutathione peroxidase and the total non-enzymatic antioxidant capacity as determined by the ferric-reducing anti-oxidant power assay. Our data demonstrate that oxidative stress does not affect follicle growth because O2– levels do not change during follicle development, whereas concentrations of H2O2 and ROOH are reduced (P < 0.05). Surprisingly, all non-enzymatic and enzymatic scavengers examined in the present study, except for CAT, demonstrated reduced activity during follicle development (P < 0.05). Taken together, these results suggest that other factors could be involved in ROS detoxification during follicle development.
Are scientific societies serving the needs of graduate and postdoctoral students?
Authors: Bahr Janice M.
Published: January 2008

Scientific societies have had a major role in facilitating scientific discoveries and disseminating them. The future of these societies is dependent on a strong and involved membership. However, many of the future members are currently graduate students and postdoctoral fellows, referred to as ‘trainees’. Therefore it is essential that these trainees understand the value of scientific societies and are eager to become members of a society of their choice. The focus of the present paper was to determine what scientific societies should do for trainees to accomplish this goal. Trainees were surveyed to determine why they joined a scientific society, what is the value of belonging to a scientific society, what can the scientific society do to advance the trainees’ career and what can trainees do to help scientific societies. From this survey, and also from years of interacting with trainees, a list of actions that scientific societies should do for their trainees was developed. There is no doubt that the most important people in educating trainees about the value of scientific societies and in influencing the trainees’ decision to be active members are the trainees’ current mentors, who have daily contact with the future members of scientific societies.
Probing concerted proton–electron transfer in phenol–imidazoles
Authors: Markle Todd F. , Rhile Ian J. , DiPasquale Antonio G. , Mayer James M.
Published: January 2008

A series of seven substituted 4,6-di-
tert
-butyl-2-(4,5-diarylimidazolyl)-phenols have been prepared and characterized, along with two related benzimidazole compounds. X-ray crystal structures of all of the compounds show that the phenol and imidazole rings are close to coplanar and are connected by an intramolecular ArOH⋯N hydrogen bond. One-electron oxidation of these compounds occurs with movement of the phenolic proton to the imidazole base by concerted proton–electron transfer (CPET) to yield fairly stable distonic radical cations. These phenol–base compounds are a valuable system in which to examine the key features of CPET. Kinetic measurements of bimolecular CPET oxidations, with
E
rxn
between +0.04 and −0.33 V, give rate constants from (6.3 ± 0.6) × 10
2
to (3.0 ± 0.6) × 10
6
M
−1
s
−1
. There is a good correlation of log(
k
) with Δ
G
°, with only one of the 15 rate constants falling more than a factor of 5.2 from the correlation line. Substituents on the imidazole affect the (O–H⋯N) hydrogen bond, as marked by variations in the
1
H NMR and calculated vibrational spectra and geometries. Crystallographic
d
O⋯N
values appear to be more strongly affected by crystal packing forces. However, there is almost no correlation of rate constants with any of these measured or computed parameters. Over this range of compounds from the same structural family, the dominant contributor to the differences in rate constant is the driving force Δ
G
°.
Variation in neural V1aR predicts sexual fidelity and space use among male prairie voles in semi-natural settings
Authors: Ophir Alexander G. , Wolff Jerry O. , Phelps Steven M.
Published: January 2008

Although prairie voles (Microtus ochrogaster) are socially monogamous, males vary in both sexual and spatial fidelity. Most males form pairbonds, cohabit with one female, and defend territories. Wandering males, in contrast, have expansive home ranges that overlap many males and females. In the laboratory, pairing is regulated by arginine vasopressin and its predominant CNS receptor, vasopressin 1a receptor (V1aR). We investigated individual differences in forebrain V1aR expression of male prairie voles in mixed-sex seminatural enclosures. Individual differences in V1aR were compared with space use measured by radio telemetry and paternity determined with microsatellite markers. Animals engaging in extra-pair fertilizations (EPFs) as either wanderers or paired residents overlapped significantly more in same- and opposite-sex home ranges. Surprisingly, neither social fidelity measured by space use nor sexual fidelity measured by paternity was associated with V1aR expression in the ventral pallidum (VPall) or lateral septum, areas causally related to pairbond formation. In contrast, V1aR expression in the posterior cingulate/retrosplenial cortex (PCing) and laterodorsal thalamus (LDThal), areas implicated in spatial memory, strongly covaried with space use and paternity. Animals engaging in EPFs either as wanderers or paired residents exhibited low levels of LDThal and PCing V1aR expression. Individual differences in brain and behavior parallel differences between prairie voles and promiscuous congeners. The concordance among space use, paternity, and V1aR in spatial circuits suggests a common link between the mechanisms of spatial behaviors and success at EPF. The combined data demonstrate how organismal biology can inform our understanding of individual and species differences in behavioral mechanisms.
Phase separation and liquid crystallization of complementary sequences in mixtures of nanoDNA oligomers
Authors: Zanchetta Giuliano , Nakata Michi , Buscaglia Marco , Bellini Tommaso , Clark Noel A.
Published: January 2008

Using optical microscopy, we have studied the phase behavior of mixtures of 12- to 22-bp-long nanoDNA oligomers. The mixtures are chosen such that only a fraction of the sample is composed of mutually complementary sequences, and hence the solutions are effectively mixtures of single-stranded and double-stranded (duplex) oligomers. When the concentrations are large enough, such mixtures phase-separate via the nucleation of duplex-rich liquid crystalline domains from an isotropic background rich in single strands. We find that the phase separation is approximately complete, thus corresponding to a spontaneous purification of duplexes from the single-strand oligos. We interpret this behavior as the combined result of the energy gain from the end-to-end stacking of duplexes and of depletion-type attractive interactions favoring the segregation of the more rigid duplexes from the flexible single strands. This form of spontaneous partitioning of complementary nDNA offers a route to purification of short duplex oligomers and, if in the presence of ligation, could provide a mode of positive feedback for the preferential synthesis of longer complementary oligomers, a mechanism of possible relevance in prebiotic environments.
High glucose induces adipogenic differentiation of muscle-derived stem cells
Authors: Aguiari Paola , Leo Sara , Zavan Barbara , Vindigni Vincenzo , Rimessi Alessandro , Bianchi Katiuscia , Franzin Chiara , Cortivo Roberta , Rossato Marco , Vettor Roberto , Abatangelo Giovanni , Pozzan Tullio , Pinton Paolo , Rizzuto Rosario
Published: January 2008

Regeneration of mesenchymal tissues depends on a resident stem cell population, that in most cases remains elusive in terms of cellular identity and differentiation signals. We here show that primary cell cultures derived from adipose tissue or skeletal muscle differentiate into adipocytes when cultured in high glucose. High glucose induces ROS production and PKCβ activation. These two events appear crucial steps in this differentiation process that can be directly induced by oxidizing agents and inhibited by PKCβ siRNA silencing. The differentiated adipocytes, when implanted
in vivo
, form viable and vascularized adipose tissue. Overall, the data highlight a previously uncharacterized differentiation route triggered by high glucose that drives not only resident stem cells of the adipose tissue but also uncommitted precursors present in muscle cells to form adipose depots. This process may represent a feed-forward cycle between the regional increase in adiposity and insulin resistance that plays a key role in the pathogenesis of diabetes mellitus.
Role of GSK3β in behavioral abnormalities induced by serotonin deficiency
Authors: Beaulieu Jean-Martin , Zhang Xiaodong , Rodriguiz Ramona M. , Sotnikova Tatyana D. , Cools Michael J. , Wetsel William C. , Gainetdinov Raul R. , Caron Marc G.
Published: January 2008

Dysregulation of brain serotonin (5-HT) neurotransmission is thought to underlie mental conditions as diverse as depression, anxiety disorders, bipolar disorder, autism, and schizophrenia. Despite treatment of these conditions with serotonergic drugs, the molecular mechanisms by which 5-HT is involved in the regulation of aberrant emotional behaviors are poorly understood. Here, we generated knockin mice expressing a mutant form of the brain 5-HT synthesis enzyme, tryptophan hydroxylase 2 (Tph2). This mutant is equivalent to a rare human variant (R441H) identified in few individuals with unipolar major depression. Expression of mutant Tph2 in mice results in markedly reduced (≈80%) brain 5-HT production and leads to behavioral abnormalities in tests assessing 5-HT-mediated emotional states. This reduction in brain 5-HT levels is accompanied by activation of glycogen synthase kinase 3β (GSK3β), a signaling molecule modulated by many psychiatric therapeutic agents. Importantly, inactivation of GSK3β in Tph2 knockin mice, using pharmacological or genetic approaches, alleviates the aberrant behaviors produced by 5-HT deficiency. These findings establish a critical role of Tph2 in the maintenance of brain serotonin homeostasis and identify GSK3β signaling as an important pathway through which brain 5-HT deficiency induces abnormal behaviors. Targeting GSK3β and related signaling events may afford therapeutic advantages for the management of certain 5-HT-related psychiatric conditions.
Arp2/3 Complex Is Important for Filopodia Formation, Growth Cone Motility, and Neuritogenesis in Neuronal Cells
Authors: Korobova Farida , Svitkina Tatyana
Published: February 2008

A role of Arp2/3 complex in lamellipodia is well established, whereas its roles in filopodia formation remain obscure. We addressed this question in neuronal cells, in which motility is heavily based on filopodia, and we found that Arp2/3 complex is involved in generation of both lamellipodia and filopodia in growth cones, and in neuritogenesis, the processes thought to occur largely in Arp2/3 complex-independent manner. Depletion of Arp2/3 complex in primary neurons and neuroblastoma cells by small interfering RNA significantly decreased the F-actin contents and inhibited lamellipodial protrusion and retrograde flow in growth cones, but also initiation and dynamics of filopodia. Using electron microscopy, immunochemistry, and gene expression, we demonstrated the presence of the Arp2/3 complex-dependent dendritic network of actin filaments in growth cones, and we showed that individual actin filaments in filopodia originated at Arp2/3 complex-dependent branch points in lamellipodia, thus providing a mechanistic explanation of Arp2/3 complex functions during filopodia formation. Additionally, Arp2/3 complex depletion led to formation of multiple neurites, erratic pattern of neurite extension, and excessive formation of stress fibers and focal adhesions. Consistent with this phenotype, RhoA activity was increased in Arp2/3 complex-depleted cells, indicating that besides nucleating actin filaments, Arp2/3 complex may influence cell motility by altering Rho GTPase signaling.
Prediction of neuropeptide cleavage sites in insects
Authors: Southey Bruce R. , Sweedler Jonathan V. , Rodriguez-Zas Sandra L.
Published: February 2008

Motivation: The production of neuropeptides from their precursor proteins is the result of a complex series of enzymatic processing steps. Often, the annotation of new neuropeptide genes from sequence information outstrips biochemical assays and so bioinformatics tools can provide rapid information on the most likely peptides produced by a gene. Predicting the final bioactive neuropeptides from precursor proteins requires accurate algorithms to determine which locations in the protein are cleaved.

Results: Predictive models were trained on Apis mellifera and Drosophila melanogaster precursors using binary logistic regression, multi-layer perceptron and k-nearest neighbor models. The final predictive models included specific amino acids at locations relative to the cleavage sites. Correct classification rates ranged from 78 to 100% indicating that the models adequately predicted cleaved and non-cleaved positions across a wide range of neuropeptide families and insect species. The model trained on D.melanogaster data had better generalization properties than the model trained on A. mellifera for the data sets considered. The reliable and consistent performance of the models in the test data sets suggests that the bioinformatics strategies proposed here can accurately predict neuropeptides in insects with sequence information based on neuropeptides with biochemical and sequence information in well-studied species.

Contact:  rodrgzzs@uiuc.edu

Supplementary information: Sequences and cleavage information are available at Bioinformatics online.
Ustilago maydispopulations tracked maize through domestication and cultivation in the Americas
Authors: Munkacsi Andrew B , Stoxen Sam , May Georgiana
Published: February 2008

The domestication of crops and the development of agricultural societies not only brought about major changes in human interactions with the environment but also in plants' interactions with the diseases that challenge them. We evaluated the impact of the domestication of maize from teosinte and the widespread cultivation of maize on the historical demography ofUstilago maydis, a fungal pathogen of maize. To determine the evolutionary response of the pathogen's populations, we obtained multilocus genotypes for 1088U. maydisdiploid individuals from two teosinte subspecies in Mexico and from maize in Mexico and throughout the Americas. Results identified five majorU. maydispopulations: two in Mexico; two in South America; and one in the United States. The two populations in Mexico diverged from the other populations at times comparable to those for the domestication of maize at 6000–10 000 years before present. Maize domestication and agriculture enforced sweeping changes inU. maydispopulations such that the standing variation in extant pathogen populations reflects evolution only since the time of the crop's domestication.
Riverine, estuarine and marine migratory behaviour and physiology of wild and hatchery‐reared coho salmon Oncorhynchus kisutch (Walbaum) smolts descending the Campbell River, BC, Canada
Authors: Chittenden C. M. , Sura S. , Butterworth K. G. , Cubitt K. F. , Plantalech Manel‐la N. , Balfry S. , ØKland F. , McKinley R. S.
Published: February 2008

Eighty coho salmon Oncorhynchus kisutch smolts (40 wild and 40 hatchery‐reared) were surgically implanted with acoustic transmitters and released into the Quinsam River over 2 days. Differences in physiology, travel time and migratory behaviour were examined between wild and hatchery‐reared fish. In addition, tagged and control fish of both wild and hatchery‐reared stock were raised for 3 months following surgery to compare survival and tag retention. Detection ranges of the acoustic receivers were tested in the river, estuary and ocean in a variety of flow conditions and tide levels. Receivers were placed in the river, estuary and up to 50 km north and south from the river mouth in the marine environment. Wild smolts were significantly smaller by mass, fork length and condition factor than hatchery‐reared smolts and exhibited significantly higher levels of sodium, potassium and chloride in their blood plasma than hatchery‐reared smolts. The gill Na+K+‐ATPase activity was also significantly higher in the wild coho smolts at the time of release. Ninety‐eight per cent of wild and 80% of hatchery‐reared fish survived to the estuary, 8 km downstream of the release site. No difference was found in migration speed, timing or survival between smolts released during daylight and those released after dark. Wild smolts, however, spent less time in the river and estuary, and as a result entered the ocean earlier than hatchery‐reared smolts. Average marine swimming speeds for wild smolts were double those of their hatchery‐reared counterparts. While hatchery smolts dispersed in both a northward and southward direction upon entering the marine environment, the majority of wild smolts travelled north from the Campbell River estuary. The wild coho salmon smolts were more physiologically fit and ready to enter sea water than the hatchery‐reared smolts, and as a result had higher early survival rates and swimming speeds.
Histone deacetylase inhibitors enhance the chemosensitivity of tumor cells with cross‐resistance to a wide range of DNA‐damaging drugs
Authors: Ozaki Kei‐ichi , Kishikawa Futaba , Tanaka Masashi , Sakamoto Toshiaki , Tanimura Susumu , Kohno Michiaki
Published: February 2008

Although DNA‐damaging agents are among the most effective anticancer drugs in clinical use, their overall effectiveness is limited by the development of cross‐resistance to these drugs. Given that histone deacetylase (HDAC) inhibitors increase the acetylation of core histones, resulting in an open chromatin configuration that is more accessible to DNA‐targeting agents, we examined whether HDAC inhibitors might enhance the cytotoxicity of DNA‐damaging drugs in six human ovarian tumor cell lines that exhibit different cisplatin sensitivities. Low concentrations of HDAC inhibitors, which alone exhibited little cytotoxicity, markedly enhanced the induction of apoptotic cell death not only by cisplatin but also by a wide variety of DNA‐targeting anticancer drugs in these tumor cell lines, irrespective of their sensitivities to the respective drugs. In contrast, HDAC inhibitors did not increase the cytotoxicity of metabolic antagonists or microtubule‐targeting agents. HDAC inhibitors potentiated both the phosphorylation of histone H2AX on serine‐139 (a marker of DNA double‐strand breaks) as well as the accumulation of reactive oxygen species induced by DNA‐damaging agents in tumor cells. The enhanced generation of reactive oxygen species appeared to be responsible for the enhanced apoptotic cell death induced by the combination of these drugs. These results indicate that the combination of an HDAC inhibitor with a wide variety of DNA‐damaging agents is a promising chemotherapeutic strategy for the eradication of tumor cells, regardless of whether the cells are sensitive or resistant to the DNA‐damaging anticancer drugs. (Cancer Sci 2008; 99: 376–384)
Tumor formation due to abnormalities in the β‐catenin‐independent pathway of Wnt signaling
Authors: Kikuchi Akira , Yamamoto Hideki
Published: February 2008

Wnt signaling is a complex pathway in which β‐catenin is typically viewed as a central mediator in regulating cell proliferation and differentiation. The significance of Wnt signaling in human cancer has been elucidated by the identification of mutations in genes coding for the β‐catenin‐dependent pathway components, adenomatous polyposis coli gene product, β‐catenin, and Axin. Within the past 15 years, evidence has been growing of a β‐catenin‐independent pathway in Wnt signaling. It is likely that this pathway activates several intracellular signaling systems to regulate cell migration, adhesion, and polarity. The β‐catenin‐independent pathway has also been shown to play an important role in tumor biology. In contrast to the β‐catenin‐dependent pathway, which is upregulated in many cancers and serves as a tumor promoter, the role of the β‐catenin‐independent pathway is still controversial. Here we review recent developments in both the functions and mechanisms of the β‐catenin‐independent pathway, with an emphasis on its functional contribution to human tumor progression. (Cancer Sci 2008; 99: 202–208)
Loss of BRCA2 promotes prostate cancer cell invasion through up‐regulation of matrix metalloproteinase‐9
Authors: Moro Loredana , Arbini Arnaldo A. , Yao Jorge L. , Di Sant’Agnese Paul A. , Marra Ersilia , Greco Margherita
Published: February 2008

BRCA2 is a multifunctional tumor suppressor protein which plays critical roles in DNA repair, transcription, and cell proliferation, and the loss of which has been linked to the biology of several types of cancers. Here, on prostate adenocarcinoma specimens from 80 patients, we demonstrate that BRCA2 protein is lost in carcinoma cells compared to normal and hyperplastic prostate epithelium. Using highly metastatic prostate cancer PC‐3 cells, we show that while BRCA2 depletion by small‐interfering RNA promoted migration onto the extracellular matrix proteins fibronectin, laminin, and collagens, as well as invasion through the reconstituted basement membrane matrix Matrigel by more than 140%, recombinant BRCA2 overexpression decreased both phenomena by 57–80% and changed cell morphology from angular and spindle to round and compact. The BRCA2 inhibitory effect on cancer cell migration and invasion resulted from down‐regulation of matrix metalloproteinase (MMP)‐9 protein levels due to increased MMP‐9 proteolysis, and was signaled through inhibition of PI3‐kinase/AKT and activation of MAPK/ERK pathway. In BRCA2‐overexpressing PC‐3 cells, transient transfection with a constitutively active PI3‐kinase mutant or treatment with the MAPK/ERK inhibitor PD98059 rescued MMP‐9 levels and restored the migratory and invasive capabilities. Consistently, PI3‐kinase inhibition with a dominant‐negative mutant or MAPK/ERK activation with a gain‐of‐function mutant reduced MMP‐9 levels and prevented migration and invasion in wild‐type PC‐3 cells. These results provide novel evidence showing that a functional BRCA2 protein may limit the metastatic potential of neoplastic cells by down‐regulating MMP‐9 production through inhibition of PI3‐kinase/AKT and activation of MAPK/ERK, effectively hindering cancer cell migration and invasion. (Cancer Sci 2008; 99: 553–563)
Non‐atopic asthma in children is related to maternal bronchial hyperreactivity
Authors: Ozdemir Cevdet , Ceyhan Berrin B. , Yazi Didem , Eifan Aarif O. , Yesil Ozlem , Bahceciler Nerin N. , Barlan Isil B.
Published: February 2008

Data on the pathogenic mechanisms underlying the development of non‐atopic asthma in children are scarce. Our aim was to evaluate the association and compare the atopic status, pulmonary functions, bronchial hyperresponsiveness and serum total immunoglobulin E (IgE) levels of parents of atopic and non‐atopic asthmatic children by using objective methods. Fifty‐one asthmatic children aged 4–16 yr and their parents were included into the study. Initially the American Thoracic Society’s Respiratory Disease questionnaire inquiring data on symptoms of asthma, rhinitis and past medical history was filled in. Afterwards, skin prick test with aeroallergens, pulmonary function and methacholine bronchial provocation tests and serum sampling for total IgE level determinations were carried out. Bronchial hyperresponsiveness to methacholine was significantly more common in the mothers of non‐atopic children compared to those of atopic ones, although no significant difference was observed in the skin prick test reactivity, pulmonary function test parameters and serum IgE levels. Questionnaire data revealed that the presence of asthmatic symptoms such as wheezing and phlegm and doctor‐diagnosed asthma were more common in the mothers of non‐atopic children. Meanwhile, asthmatic symptoms were also found to be significantly more common in fathers of non‐atopic children. Logistic regression analyses revealed that maternal PC20 was the only predictive factor for the risk of displaying non‐allergic asthma in children. The results demonstrate that among the risk factors studied, maternal bronchial hyperreactivity was associated with the development of asthma in non‐atopic children.
Decay of unused characters by selection and drift
Authors: HALL A. R. , COLEGRAVE N.
Published: February 2008

The reduction and loss of redundant phenotypic characters is a common feature of evolution. However, the mechanisms that drive deterioration of unused characters remain unclear. Here, we outline a simple framework where the relative importance of selective and neutral processes varies with environmental factors, because of variation in the fitness costs associated with unused traits. We tested our hypotheses using experimental evolution of the bacterium Pseudomonas fluorescens in spatially uniform environments. Results show that an unused character, swimming motility, decayed over evolutionary time and the rate of this decay varied among selection environments with different levels of resource availability. This is explained in the context of an environment‐specific genetic correlation between motility and fitness, which is negative when resources are limited but neutral at higher resource levels. Thus, selection against an unused character was most effective in environments where the fitness cost was the greatest. This suggests that the same character can decay by different mechanisms depending upon environmental factors and supports previous evidence to show that resource availability can critically affect the outcomes of evolution.
A hybrid zone dominated by fertile F1s of two alpine shrub species,Phyllodoce caeruleaandPhyllodoce aleutica, along a snowmelt gradient
Authors: KAMEYAMA Y. , KASAGI T. , KUDO G.
Published: February 2008

In alpine ecosystems, the steep environmental gradients produced by the difference in snowmelt timing create a dynamic selective regime for alpine plants. As these gradients directly alter flowering phenology, they can affect pollen‐mediated gene flow among populations of single and related species. In northern Japan, we found a hybrid zone dominated by fertile F1s of two alpine shrub species,Phyllodoce caeruleaandP. aleutica, along a snowmelt gradient. Seed germination confirmed the fertility of F1hybrid, making the rarity and absence of backcross and F2plants puzzling. The long‐term clonal perpetuation of F1hybrids (at least a few thousand years ago) contributes the maintenance of this unique hybrid zone. The distribution patterns of chloroplast DNA haplotypes suggest that F1formation might be caused by directional pollen flow between parental species along the snowmelt gradient. Based on these results, we discuss the ecological and evolutionary significance of this unique hybrid zone.
Apparent mutational hotspots and long distance linkage disequilibrium resulting from a bottleneck
Authors: TENAILLON M. I. , AUSTERLITZ F. , TENAILLON O.
Published: February 2008

Genome wide patterns of nucleotide diversity and recombination reveal considerable variation including hotspots. Some studies suggest that these patterns are primarily dictated by individual locus history related at a broader scale to the population demographic history. Because bottlenecks have occurred in the history of numerous species, we undertook a simulation approach to investigate their impact on the patterns of aggregation of polymorphic sites and linkage disequilibrium (LD). We developed a new index (Polymorphism Aggregation Index) to characterize this aggregation and showed that variation in the density of polymorphic sites results from an interplay between the bottleneck scenario and the recombination rate. Under particular conditions, aggregation is maximized and apparent mutation hotspots resulting in a 50‐fold increase in polymorphic sites density can occur. In similar conditions, long distance LD can be detected.
MORPHOLOGICAL STUDIES RELATING TO THE FRACTURE STRESS AND FRACTURE TOUGHNESS OF SILICON NITRIDE
Authors: Chu M. C. , Sato S. , Kobayashi Y. , Ando K.
Published: February 2008

Abstract— Microstructure and mechanical properties of HP (Hot Pressed), HP/GP (Gas Pressed), and HP/HIP (Hot Isostatic Pressed)—Si3N4 are studied using scanning electron microscopy, bending tests and the indentation fracture method. The grain diameter distribution is analyzed to clarify the relationship between microstructure and mechanical properties; and also the bending strength and fracture toughness. It is shown that bending strength increases with decreasing grain diameter. The results also show that a Hall—Petch type of relationship is obtained between grain diameter and fracture strength. The fracture toughness shows a linear relationship with , where σF= bending strength, β= a proportionality factor and da= average grain diameter, and is closely related to the aspect ratio of Si3N4 grains. It is concluded, from the morphological analysis, that a microstructure composed of Si3N4 grains, with both a small grain diameter and a large aspect ratio, is effective in improving both the fracture strength and fracture toughness.
THE FREQUENCY RESPONSE MODEL OF THERMAL STRIPING FOR CYLINDRICAL GEOMETRIES
Authors: Jones I. S.
Published: February 2008

Abstract— The random temperature fluctuation produced by the incomplete mixing of hot and cold fluid streams passing over the surface of a component or structure is known as thermal striping. This phenomenon may cause thermal fatigue to occur. It is of particular concern in various types of nuclear reactors, for rapid shut‐downs of hot plant and in thermal stratification. A computer code, “TBL”, is a design tool which has been developed to assess thermal striping damage in plates. This model is further developed in this paper to assess such damage in cylindrical components. A recent, universal weight function method is examined and incorporated into TBL. Good comparisons are found between TBL and finite element results for a sinusoidally varying temperature‐time‐striping history. Potential thermal striping damage is assessed for a cylindrical component of material typically found in the above‐core region of a fast reactor under a random temperature‐time‐striping history.
m‐Learning: An experiment in using SMS to support learning new English language words
Authors: Cavus Nadire , Ibrahim Dogan
Published: February 2008

There is an increase use of wireless technologies in education all over the world. In fact, wireless technologies such as laptop computers, palmtop computers and mobile phones are revolutionising education and transforming the traditional classroom‐based learning and teaching into anytime and anywhere education. This paper investigates the use of wireless technologies in education with particular reference to the potential of learning new technical English language words using Short Message Service (SMS) text messaging. The system, developed by the authors, called mobile learning tool (MOLT), has been tested with 45 1st‐year undergraduate students. The knowledge of students before and after the experiment has been measured. Our results show that students enjoyed and learned new words with the help of their mobile phones. We believe that using the MOLT system as an educational tool will contribute to the success of students.
Changing the Boundaries but Keeping the Disproportionality: The Electoral Impact of the Fifth Periodical Reviews by the Parliamentary Boundary Commissions for England and Wales
Authors: RALLINGS COLIN , JOHNSTON RON , THRASHER MICHAEL
Published: February 2008

Parliamentary boundary reviews in the UK are undertaken to remove — as far as is practicable — inter‐constituency variations in the number of electors. Their impact has almost invariably favoured the Conservative party — largely because population shifts between reviews tend to favour Labour with the movement of electors away from the inner cities and old industrial areas. That has been the case again with the Fifth Periodical Reviews conducted by the Boundary Commissions for England and Wales. The next general election will thus be slightly easier for the Conservatives to win than if the boundaries used for the 2005 contest were to be retained. But not much easier. Recent elections have seen very substantial biases operating in the translation of votes into seats favouring Labour. The biases are the result of the interaction of several geographies — of constituency size, abstentions and party support‐ only one of which (size) is directly tackled by the reviews. Unless those other geographies are changed the next two or three UK general elections are likely to see a continuation of these marked biases.
Plural Agents
Authors: Helm Bennett W.
Published: February 2008

Genuine agents are able to engage in activity because they find it worth pursuing—because they care about it. In this respect, they differ from what might be called “mere intentional systems”: systems like chess‐playing computers that exhibit merely goal‐directed behavior mediated by instrumental rationality, without caring. A parallel distinction can be made in the domain of social activity: plural agents must be distinguished from plural intentional systems in that plural agents have cares and engage in activity because of those cares. In this paper, I sketch an account of what it is for an individual to care about things in terms of her exhibiting a certain pattern of emotions. After extending this account to make sense of an individual's caring about other agents, I then show how a certain sort of emotional connectedness among a group of people can make intelligible the group's having cares and thereby constitute that group as a plural agent. Alternative accounts of social action, by ignoring the difference between mere intentional systems and genuine agents, and so by leaving out these emotional entanglements from their accounts of social action, thereby fail to capture a whole range of social phenomena involving plural agents.
2. REASONS, GENERALIZATIONS, EMPATHY, AND NARRATIVES: THE EPISTEMIC STRUCTURE OF ACTION EXPLANATION
Authors: STUEBER KARSTEN R.
Published: February 2008

It has become something of a consensus among philosophers of history that historians, in contrast to natural scientists, explain in a narrative fashion. Unfortunately, philosophers of history have not said much about how it is that narratives have explanatory power. They do, however, maintain that a narrative's explanatory power is sui generis and independent of our empathetic or reenactive capacities and of our knowledge of law‐like generalizations. In this article I will show that this consensus is mistaken at least in respect to explanatory strategies used to account for rational agency using the “folk‐psychological” framework of intentions, beliefs, desires, and the like. Philosophers distinguish insufficiently among different aspects and different types of information needed for a historian to persuasively account for an agent's behavior in particular circumstances. If one keeps these aspects apart it will become apparent exactly how one should understand the epistemic contribution of empathy, generalizations, and narrative for the explanation of action.
Lovastatin inhibits amyloid precursor protein (APP) β‐cleavage through reduction of APP distribution in Lubrol WX extractable low density lipid rafts
Authors: Won Je‐Seong , Im Yeong‐Bin , Khan Mushfiquddin , Contreras Miguel , Singh Avtar K. , Singh Inderjit
Published: February 2008

Previous studies have described that statins (inhibitors of cholesterol and isoprenoid biosynthesis) inhibit the output of amyloid‐β (Aβ) in the animal model and thus decrease risk of Alzheimer’s disease. However, their action mechanism(s) in Aβ precursor protein (APP) processing and Aβ generation is not fully understood. In this study, we report that lovastatin treatment reduced Aβ output in cultured hippocampal neurons as a result of reduced APP levels and β‐secretase activities in low density Lubrol WX (non‐ionic detergent) extractable lipid rafts (LDLR). Rather than altering cholesterol levels in lipid raft fractions and thus disrupting lipid raft structure, lovastatin decreased Aβ generation through down‐regulating geranylgeranyl‐pyrophosphate dependent endocytosis pathway. The inhibition of APP endocytosis by treatment with lovastatin and reduction of APP levels in LDLR fractions by treatment with phenylarsine oxide (a general endocytosis inhibitor) support the involvement of APP endocytosis in APP distribution in LDLR fractions and subsequent APP β‐cleavage. Moreover, lovastatin‐mediated down‐regulation of endocytosis regulators, such as early endosomal antigen 1, dynamin‐1, and phosphatidylinositol 3‐kinase activity, indicates that lovastatin modulates APP endocytosis possibly through its pleiotropic effects on endocytic regulators. Collectively, these data report that lovastatin mediates inhibition of LDLR distribution and β‐cleavage of APP in a geranylgeranyl‐pyrophosphate and endocytosis‐dependent manner.
DIVERSITY AND HOST SPECIFICITY OF AZOLLA CYANOBIONTS1
Authors: Papaefthimiou Dimitra , Van Hove Charles , Lejeune André , Rasmussen Ulla , Wilmotte Annick
Published: February 2008

A unique, hereditary symbiosis exists between the water fern Azolla and cyanobacteria that reside within a cavity in the dorsal leaf‐lobe of the plant. This association has been studied extensively, and questions have frequently been raised regarding the number and diversity of cyanobionts (cyanobacterial symbionts) among the different Azolla strains and species. In this work, denaturating gradient gel electrophoresis (DGGE) and a clone library based on the 16S rRNA gene were used to study the genetic diversity and host specificity of the cyanobionts in 35 Azolla strains covering a wide taxonomic and geographic range. DNA was extracted directly from the cyanobacterial packets, isolated after enzymatic digestion of the Azolla leaves. Our results indicated the existence of different cyanobiont strains among Azolla species, and diversity within a single Azolla species, independent of the geographic origin of the host. Furthermore, the cyanobiont exhibited host‐species specificity and showed most divergence between the two sections of genus Azolla, Azolla and Rhizosperma. These findings are in agreement with the recent redefinition of the taxon Azolla cristata within the section Azolla. With regard to the taxonomic status of the cyanobiont, the genus Anabaena of the Nostocaceae family was identified as the closest relative by this work.
IDENTIFICATION OF GENES PREFERENTIALLY EXPRESSED DURING ASEXUAL SPORULATION IN PORPHYRA YEZOENSIS GAMETOPHYTES (BANGIALES, RHODOPHYTA)1
Authors: Kitade Yukihiro , Asamizu Erika , Fukuda Satoru , Nakajima Maiko , Ootsuka Shuuji , Endo Hirotoshi , Tabata Satoshi , Saga Naotsune
Published: February 2008

Asexual reproduction via archeospores in Porphyra yezoensis Ueda gametophytes is a very valuable character to nori farming; however, there is little information available on the molecular basis of the developmental process. To identify genes involved in the Porphyra asexual sporulation, we compared the gene expression profiles derived from four developmental stages of the life cycle (three from gametophytes; one from sporophytes) using cDNA macroarray, which includes 4,896 nonredundant expressed sequence tag (EST) groups. Candidate genes were screened by two different macroarray data analyses combined with reverse transcription‐PCR (RT‐PCR) analysis or Northern analysis. RT‐PCR analysis revealed that nine genes (one: similarity to 5′–3′ exoribonuclease; the other eight: no sequence similarity to known proteins) were expressed with a gametophyte (G)–specific manner, and two genes (named ASPO2608, ASPO1527) were expressed only in gametophytes that formed archeospores. The deduced amino acid sequences for the latter two genes are predicted to contain signal peptides for secretion at their N‐termini. Northern analysis revealed that expression levels of Calvin cycle genes in the gametophytic stage that formed archeospores (G‐A stage) were higher than those of the gametophyte blade with no archeospores (G‐NA stage). In the macroarray analysis based on the rank data of G‐preferentially expressed genes, which were detected in the previous P. yezoensis EST analysis, one gene encoding the cyclase associated protein (CAP) exhibited a change upwardly in the G‐A stage >1,000 ranks to the G‐NA stage. We propose that ASPO2608 and CAP may function in a signaling pathway of asexual sporulation.
Cryptic splicing sites are differentially utilized in vivo
Authors: Haj Khelil Amel , Deguillien Mireille , Morinière Madeleine , Ben Chibani Jemni , Baklouti Faouzi
Published: February 2008

It has long been considered that cryptic splice sites are ignored by the splicing machinery in the context of intact genuine splice sites. In the present study, it is shown that cryptic splice sites are utilized in all circumstances, when the authentic site is intact, partially functional or completely abolished. Their use would therefore contribute to a background lack of fidelity in the context of the wild‐type sequence. We also found that a mutation at the 5′ splice site of β‐globin intron 1 accomodates multiple cryptic splicing pathways, including three previously reported pathways. Focusing on the two major cryptic 5′ splice sites within β‐globin exon 1, we show that cryptic splice site selection ex vivo varies depending upon: (a) the cell stage of development during terminal erythroid differentiation; (b) the nature of the mutation at the authentic 5′ splice site; and (c) the nature of the promoter. Finally, we found that the two major cryptic 5′ splice sites are utilized with differential efficiencies in two siblings sharing the same β‐globin chromosome haplotype in the homozygous state. Collectively, these data suggest that intrinsic, sequence specific factors and cell genetic background factors both contribute to promote a subtle differential use of cryptic splice sites in vivo.
Pressurized Liquid Extraction of Flavonoids from Spinach
Authors: Howard L. , Pandjaitan N.
Published: February 2008

ABSTRACT:  Pressurized liquid extraction (PLE) using water and a 70:30 mixture of ethanol and water over the temperature range of 50 to 190 °C was used to extract flavonoids from dried spinach. The total phenolic content, antioxidant capacity, color, and browning indices of the extracts were also evaluated. PLE using a 70:30 mixture of ethanol and water was more effective than water in extracting flavonoids from spinach. Flavonoids were effectively extracted over the temperature band of 50 to 130 °C with water and 50 to 150 °C with ethanolic solvent. Levels of total phenolics and ORAC values increased with increasing extraction temperature, indicating that flavonoids were minor contributors to antioxidant capacity at elevated extraction temperatures. Browning of ethanolic extracts correlated highly with ORAC values over the temperature range of 50 to 190 °C, and the ORAC values of the large molecular weight fraction (> 1000 Da) increased linearly over the temperature range, indicating that Maillard polymers were the major contributors to antioxidant capacity. The results illustrate that PLE temperatures of < 130 °C for water or < 150 °C for ethanolic solvent may be used to extract flavonoids, followed by a high temperature (> 170 °C) extraction to generate antioxidant‐rich moieties.
PRIMARY STEPS OF PHOTOCHEMICAL REACTIONS IN PROTEINS AND AROMATIC AMINO‐ACIDS: A REVIEW*
Authors: Vladimirov Yu. A.
Published: February 2008

Abstract— Studies of the luminescence and excitation spectra of proteins showed that in proteins, in contrast with mixed crystals of the amino acids, the migration of energy from tyrosine to tryptophan takes place in low yield. The migration of energy between nucleotides and from nucleotides to acridine orange in DNA proceeded with an average yield of 66%.

The luminescence of more than ten proteins studied, at pH 1.0–13.0, temperatures from — 196 to + 100°C and monochromatic excitation from 240 to 303 mp was established as due to the luminescence of tyrosine and tryptophan. The amounts of energy stored by the molecules of these compounds in singlet and triplet excited states were 80 and 60 Kcal./ mole respectively. A sudden difference in the structure of the phosphorescence and fluorescence spectra suggests that the transition to the triplet state is connected with changes in the vibrational configurations of the molecules, which prepare conditions for a photochemical event. The enhanced probability of an S →T transition during a change in pH or the addition of KI always led to an increase in the rate of ‘fading’ of luminescence under irradiation by the exciting light.

A comparison of the kinetics of bleaching of the luminescence of samples with low‐temperature thermoluminescence showed that two photo‐products had been formed under U.V. irradiation at 77°K. Product Rt, responsible for the thermoluminescence, recombined through the triplet state with the emission of a quantum on warming to 80–100°K or on supplementary irradiation by visible light. Product Rb, accumulating on fading of the original, was stable to light and was transformed to the original amino acid without emitting a quantum at a temperature of 150–200° K. At room temperature aromatic amino acid groups entered into two photo‐chemical reactions: (1) photo‐oxidation by atmospheric oxygen and (2) reaction with adjoining groups of the protein, not requiring the presence of oxygen. Reaction (2), probably the main one for peptides and proteins, may lead to the formation of cross links between peptide chains, and to photoinactivation.