bluuebunny/crossref_metadata_2025 huggingface dataset:
Morphology-dependent field emission characteristics of SiC nanowires
Authors: Li Z. J. , Ren W. P. , Meng A. L.
Published: December 2010

Felted, curly, and straight β-SiC nanowires (SiCNWs) had been synthesized by chemical vapor reaction, and morphology-dependent field emission (FE) characteristics were chiefly investigated. The turn-on and threshold fields were 2.0 and 5.3 V/μm for felted nanowires, 1.5 and 3.25 V/μm for curly nanowires, and 1.0 and 2.05 V/μm for straight nanowires, respectively, suggesting that morphology played an important role in FE properties of the SiCNWs. Magnetic field shielding effect is proposed to explain the morphology-dependent FE characteristics, and it may stand as a nice referential work for researching FE properties of other wirelike materials.
Stepwise cosensitization through chemically bonding organic dye to CdS quantum-dot-sensitized TiO2 electrode
Authors: So Seulgi , Fan Sheng-Qiang , Choi Hyunbong , Kim Chulwoo , Cho Nara , Song Kihyung , Ko Jaejung
Published: December 2010

An organic dye (JK218) with thiol moiety as an anchoring group was synthesized and explored to assemble a cosensitized TiO2 electrode in combination with an inorganic CdS quantum-dot. Due to the selective adsorption of JK218 on the surface of CdS through thiol group, the developed cosensitized electrode demonstrates cascade architecture with CdS coating on TiO2 while JK218 functions as a covering on CdS. Most importantly, the energy levels of the TiO2–CdS-JK218 electrode were also found to be stepwise aligned, which accordingly makes electrons efficiently inject from JK218 to CdS under illumination and finally collect to TiO2. This constructed cosensitized electrode with an organic sensitizer (JK218) and an inorganic quantum-dot (CdS) being selectively bonded together is expected to be valuable for the interface design of next generation solar cells.
Modification of magnetic and magnetocaloric properties of Dy–Co–Al bulk metallic glass introduced by hydrogen
Authors: Fu H. , Zou M. , Singh Niraj K.
Published: December 2010

Dy 53.8 Co 17.3 Al 28.9 bulk metallic glass with a diameter of 3 mm exhibits spin-glass behavior and large coercivity and remanence. Hydrogenation of Dy53.8Co17.3Al28.9 suppresses the magnetic transition temperature and removes coercivity and remanence because of the expansion of average interatomic distance. The advantage of large magnetic entropy changes (17.5 and 9.5 J/kg K for the field changes from 0 to 50, and from 0 to 20 kOe, respectively) without any hysteresis loss makes Dy53.8Co17.3Al28.9 H170.6 alloy a promising magnetic refrigerant.
The largest neutron-star mass yet recorded has broad implications
Authors: Schwarzschild Bertram M.
Published: December 2010

If neutron stars can be twice as massive as the Sun, most conjectures about exotic states of matter at maximum compression are ruled out.
Optical measurements probe the pressure and density of water under tension
Authors: Miller Johanna L.
Published: December 2010

Little is known about the thermodynamics of the familiar liquid’s metastable phases.
Gamma rays made on Earth have unexpectedly high energies
Authors: Miller Johanna L.
Published: December 2010

The as-yet-unexplained observation represents a crossover between astrophysical and atmospheric research.
Exploring the extremes of turbulence
Authors: Smart Ashley G.
Published: December 2010

Two experiments yield similar data but tell different stories about momentum transport at high Reynolds numbers.
China is latest country to pursue astronomy in Antarctica
Authors: Feder Toni
Published: December 2010

At some wavelengths, the advantages of doing astronomy from Antarctica outweigh the challenges.
Shortage of plutonium-238 jeopardizes NASA’s planetary science missions
Authors: Kramer David
Published: December 2010

Scientific societies and advisers urge Congress to approve funding to restart production of the radioisotope, which provides the only alternative to solar power for spacecraft.
National initiatives recruit and retrain science teachers
Authors: Matthews Jermey N. A.
Published: December 2010

Businesses, nonprofit organizations, and the White House are betting on K–12 STEM teachers to forestall the “gathering storm” forecasted by the National Academies.
A new look at the planet Mercury
Authors: Solomon Sean C.
Published: December 2010

MESSENGER spacecraft goes into orbit around Mercury in March 2011, but its three flybys have already offered a fresh perspective on the planet’s history, composition, and magnetic field.
Focus on photonics and biomedical optics
Authors: Mandelis Andreas
Published: December 2010

The descriptions of the new products listed in this section are based on information supplied to us by the manufacturers. PHYSICS TODAY can assume no responsibility for their accuracy. For more information about a particular product, visit the website at the end of the product description.
The discrete charm of rain
Authors: Ignaccolo Massimiliano , De Michele Carlo
Published: December 2010

Weather reports and many scientific models treat rainfall as a continuous process, but to truly understand rain and its effects, one must consider its fundamentally discrete nature.
Structural basis for piRNA 2'-O-methylated 3'-end recognition by Piwi PAZ (Piwi/Argonaute/Zwille) domains
Authors: Tian Yuan , Simanshu Dhirendra K. , Ma Jin-Biao , Patel Dinshaw J.
Published: December 2010

Argonaute and Piwi proteins are key players in the RNA silencing pathway, with the former interacting with micro-RNAs (miRNAs) and siRNAs, whereas the latter targets piwi-interacting RNAs (piRNAs) that are 2′-O-methylated (2
′
-OCH
3
) at their 3′ ends. Germline-specific piRNAs and Piwi proteins play a critical role in genome defense against transposable elements, thereby protecting the genome against transposon-induced defects in gametogenesis and fertility. Humans contain four Piwi family proteins designated Hiwi1, Hiwi2, Hiwi3, and Hili. We report on the structures of Hili-PAZ (Piwi/Argonaute/Zwille) domain in the free state and Hiwi1 PAZ domain bound to self-complementary 14-mer RNAs (12-bp + 2-nt overhang) containing 2
′
-OCH
3
and 2′-OH at their 3′ ends. These structures explain the molecular basis underlying accommodation of the 2
′
-OCH
3
group within a preformed Hiwi1 PAZ domain binding pocket, whose hydrophobic characteristics account for the preferential binding of 2
′
-OCH
3
over 2′-OH 3′ ends. These results contrast with the more restricted binding pocket for the human Ago1 PAZ domain, which exhibits a reverse order, with preferential binding of 2′-OH over 2
′
-OCH
3
3′ ends.
Principal network analysis: identification of subnetworks representing major dynamics using gene expression data
Authors: Kim Yongsoo , Kim Taek-Kyun , Kim Yungu , Yoo Jiho , You Sungyong , Lee Inyoul , Carlson George , Hood Leroy , Choi Seungjin , Hwang Daehee
Published: December 2010

Motivation: Systems biology attempts to describe complex systems behaviors in terms of dynamic operations of biological networks. However, there is lack of tools that can effectively decode complex network dynamics over multiple conditions.

Results: We present principal network analysis (PNA) that can automatically capture major dynamic activation patterns over multiple conditions and then generate protein and metabolic subnetworks for the captured patterns. We first demonstrated the utility of this method by applying it to a synthetic dataset. The results showed that PNA correctly captured the subnetworks representing dynamics in the data. We further applied PNA to two time-course gene expression profiles collected from (i) MCF7 cells after treatments of HRG at multiple doses and (ii) brain samples of four strains of mice infected with two prion strains. The resulting subnetworks and their interactions revealed network dynamics associated with HRG dose-dependent regulation of cell proliferation and differentiation and early PrPSc accumulation during prion infection.

Availability: The web-based software is available at: http://sbm.postech.ac.kr/pna.

Contact:  dhhwang@postech.ac.kr; seungjin@postech.ac.kr

Supplementary information:  Supplementary data are available at Bioinformatics online.
Discovering approximate-associated sequence patterns for protein–DNA interactions
Authors: Chan Tak-Ming , Wong Ka-Chun , Lee Kin-Hong , Wong Man-Hon , Lau Chi-Kong , Tsui Stephen Kwok-Wing , Leung Kwong-Sak
Published: December 2010

Motivation: The bindings between transcription factors (TFs) and transcription factor binding sites (TFBSs) are fundamental protein–DNA interactions in transcriptional regulation. Extensive efforts have been made to better understand the protein–DNA interactions. Recent mining on exact TF–TFBS-associated sequence patterns (rules) has shown great potentials and achieved very promising results. However, exact rules cannot handle variations in real data, resulting in limited informative rules. In this article, we generalize the exact rules to approximate ones for both TFs and TFBSs, which are essential for biological variations.

Results: A progressive approach is proposed to address the approximation to alleviate the computational requirements. Firstly, similar TFBSs are grouped from the available TF–TFBS data (TRANSFAC database). Secondly, approximate and highly conserved binding cores are discovered from TF sequences corresponding to each TFBS group. A customized algorithm is developed for the specific objective. We discover the approximate TF–TFBS rules by associating the grouped TFBS consensuses and TF cores. The rules discovered are evaluated by matching (verifying with) the actual protein–DNA binding pairs from Protein Data Bank (PDB) 3D structures. The approximate results exhibit many more verified rules and up to 300% better verification ratios than the exact ones. The customized algorithm achieves over 73% better verification ratios than traditional methods. Approximate rules (64–79%) are shown statistically significant. Detailed variation analysis and conservation verification on NCBI records demonstrate that the approximate rules reveal both the flexible and specific protein–DNA interactions accurately. The approximate TF–TFBS rules discovered show great generalized capability of exploring more informative binding rules.

Availability:  Supplementary Data are available on Bioinformatics online and http://www.cse.cuhk.edu.hk/.

Contact:  tmchan@cse.cuhk.edu.hk
Cancer therapy design based on pathway logic
Authors: Layek Ritwik , Datta Aniruddha , Bittner Michael , Dougherty Edward R.
Published: December 2010

Motivation: Cancer encompasses various diseases associated with loss of cell cycle control, leading to uncontrolled cell proliferation and/or reduced apoptosis. Cancer is usually caused by malfunction(s) in the cellular signaling pathways. Malfunctions occur in different ways and at different locations in a pathway. Consequently, therapy design should first identify the location and type of malfunction to arrive at a suitable drug combination.

Results: We consider the growth factor (GF) signaling pathways, widely studied in the context of cancer. Interactions between different pathway components are modeled using Boolean logic gates. All possible single malfunctions in the resulting circuit are enumerated and responses of the different malfunctioning circuits to a ‘test’ input are used to group the malfunctions into classes. Effects of different drugs, targeting different parts of the Boolean circuit, are taken into account in deciding drug efficacy, thereby mapping each malfunction to an appropriate set of drugs.

Contact:  edward@ece.tamu.edu
Inferential Network Analysis with Exponential Random Graph Models
Authors: Cranmer Skyler J. , Desmarais Bruce A.
Published: December 2010

Methods for descriptive network analysis have reached statistical maturity and general acceptance across the social sciences in recent years. However, methods for statistical inference with network data remain fledgling by comparison. We introduce and evaluate a general model for inference with network data, the Exponential Random Graph Model (ERGM) and several of its recent extensions. The ERGM simultaneously allows both inference on covariates and for arbitrarily complex network structures to be modeled. Our contributions are three-fold: beyond introducing the ERGM and discussing its limitations, we discuss extensions to the model that allow for the analysis of non-binary and longitudinally observed networks and show through applications that network-based inference can improve our understanding of political phenomena.
Analysis of TETRAKETIDE α-PYRONE REDUCTASE Function in Arabidopsis thaliana Reveals a Previously Unknown, but Conserved, Biochemical Pathway in Sporopollenin Monomer Biosynthesis
Authors: Grienenberger Etienne , Kim Sung Soo , Lallemand Benjamin , Geoffroy Pierrette , Heintz Dimitri , Souza Clarice de Azevedo , Heitz Thierry , Douglas Carl J. , Legrand Michel
Published: December 2010

The precise structure of the sporopollenin polymer that is the major constituent of exine, the outer pollen wall, remains poorly understood. Recently, characterization of Arabidopsis thaliana genes and corresponding enzymes involved in exine formation has demonstrated the role of fatty acid derivatives as precursors of sporopollenin building units. Fatty acyl-CoA esters synthesized by ACYL-COA SYNTHETASE5 (ACOS5) are condensed with malonyl-CoA by POLYKETIDE SYNTHASE A (PKSA) and PKSB to yield α-pyrone polyketides required for exine formation. Here, we show that two closely related genes encoding oxidoreductases are specifically and transiently expressed in tapetal cells during microspore development in Arabidopsis anthers. Mutants compromised in expression of the reductases displayed a range of pollen exine layer defects, depending on the mutant allele. Phylogenetic studies indicated that the two reductases belong to a large reductase/dehydrogenase gene family and cluster in two distinct clades with putative orthologs from several angiosperm lineages and the moss Physcomitrella patens. Recombinant proteins produced in bacteria reduced the carbonyl function of tetraketide α-pyrone compounds synthesized by PKSA/B, and the proteins were therefore named TETRAKETIDE α-PYRONE REDUCTASE1 (TKPR1) and TKPR2 (previously called DRL1 and CCRL6, respectively). TKPR activities, together with those of ACOS5 and PKSA/B, identify a conserved biosynthetic pathway leading to hydroxylated α-pyrone compounds that were previously unknown to be sporopollenin precursors.
EXPO, an Exocyst-Positive Organelle Distinct from Multivesicular Endosomes and Autophagosomes, Mediates Cytosol to Cell Wall Exocytosis inArabidopsisand Tobacco Cells
Authors: Wang Juan , Ding Yu , Wang Junqi , Hillmer Stefan , Miao Yansong , Lo Sze Wan , Wang Xiangfeng , Robinson David G. , Jiang Liwen
Published: December 2010

The exocyst protein complex mediates vesicle fusion with the plasma membrane. By expressing an (X)FP-tagged Arabidopsis thaliana homolog of the exocyst protein Exo70 in suspension-cultured Arabidopsis and tobacco (Nicotiana tabacum) BY-2 cells, and using antibodies specific for Exo70, we detected a compartment, which we term EXPO (for exocyst positive organelles). Standard markers for the Golgi apparatus, the trans-Golgi network/early endosome, and the multivesicular body/late endosome in plants do not colocalize with EXPO. Inhibitors of the secretory and endocytic pathways also do not affect EXPO. Exo70E2-(X)FP also locates to the plasma membrane (PM) as discrete punctae and is secreted outside of the cells. Immunogold labeling of sections cut from high-pressure frozen samples reveal EXPO to be spherical double membrane structures resembling autophagosomes. However, unlike autophagosomes, EXPOs are not induced by starvation and do not fuse with the lytic compartment or with endosomes. Instead, they fuse with the PM, releasing a single membrane vesicle into the cell wall. EXPOs are also found in other cell types, including root tips, root hair cells, and pollen grains. EXPOs therefore represent a form of unconventional secretion unique to plants.
Long‐term effects on sward composition and animal performance of reducing fertilizer inputs to upland permanent pasture
Authors: Yu Y.‐W. , Fraser M. D. , Evans J. G.
Published: December 2010

This study investigated the long‐term effects on sward composition and animal performance of applying different fertilizer regimes to upland permanent pasture. The experiment, which was carried out in 2008, was based on a set of replicated (n = 3) plots that had been established in 1990. The effects of applying (i) N, P, K and lime, (ii) P and K plus lime and (iii) lime only were compared with a treatment that received no nutrient applications. Using a put‐and‐take stocking system, the plots were grazed to a target sward surface height of 4 cm by ewes and lambs from April to early August and by ewes only from August to mid‐October. The long‐term reduction in nutrient inputs had led to decreases in the percentages of both sown and unsown grass species within the sward (P < 0·05), and an increase in the percentage of mosses and litter (P < 0·05), with a corresponding reduction in nutritional value. Although there were no statistically significant treatment‐related differences in lamb growth rates, lower fertilizer inputs were associated with a marked decline in stock carrying capacity and associated overall productivity during both the pre‐ and post‐weaning periods (P < 0·001). The findings highlight the challenges faced when attempting to reconcile production and environmental objectives in upland systems.
Selective preying of the sphecid wasp Trachypus boharti on the meliponine bee Scaptotrigona postica: potential involvement of caste‐specific cuticular hydrocarbons
Authors: KOEDAM DIRK , MORGAN E. DAVID , NUNES TÚLIO M. , PATRICIO EDA FLÁVIA L. R. A. , IMPERATRIZ‐ FONSECA VERA L.
Published: December 2010

The specialist digger wasp Trachypus boharti Rubio‐Espina preys exclusively on males of the stingless bee Scaptotrigona postica Latreille 1807, although the hunting attacks involve both male and worker bees of S. postica and members of its own species. To understand the mechanism of prey selection, the cuticular hydrocarbon patterns of workers and males of S. postica are analyzed in detail, and the mandibular secretion of males is examined. The cuticular profiles of males and workers are distinctively different. The major group of cuticular compounds, heptacosene isomers, is twice as abundant in workers as in males. There is no clear distinction between worker and male mandibular secretions. Such a distinct and straightforward caste‐specific difference in cuticular hydrocarbons could function as a recognition cue by which T. boharti distinguishes between workers and males of S. postica.
Cultivation with Untransfected Fibroblasts Stimulates Proliferation of a Single Gene‐Modified Fibroblast Derived from a Clawn Miniature Swine Foetus
Authors: Sato M , Yoshida M , Miyoshi K , Ohtsuka M , Watanabe S
Published: December 2010

Contents

Porcine embryonic fibroblasts (PEFs) have been used extensively as donor nuclei for the production of cloned pigs via somatic cell nuclear transfer (SCNT). Somatic cell nuclear transfer of gene‐targeted PEFs has been the only way to produce gene‐targeted pigs, given the lack of germ‐line‐competent porcine embryonic stem cells. Unlike other primary‐cultured cells, such as murine embryonic fibroblasts, a single porcine PEF is unable to proliferate under normal conditions in which a certain number of PEFs (likely over 100) can grow normally. This limitation greatly hampers re‐cloning of gene‐modified PEFs, which is required for SCNT. Herein, we demonstrate the cultivation of a single PEF transfectant carrying the pEGFP‐N1 plasmid with intact normal PEFs (>100) in a Terasaki microtest plate, which resulted in stimulation of the growth of the former cell (doubling time = 2.6 days). In contrast, when a single cell was cultured, it could typically divide only once and never divided more than twice. When a single transfectant was seeded in a well of a 96‐well plate together with 5 × 104 untransfected PEFs and was subsequently selected in the presence of G418, we obtained a pure cell population of single‐cell origin. Thus, this method should be useful for the purification of target recombinant pig clones from mosaic populations that cannot be cultured as a single cell or for which suitable cell growth‐promoting conditions are unclear.
Effects of Season and Superovulatory Treatment on Embryo Yields in Fine‐Wool Merinos Maintained Under Field Conditions
Authors: Cueto MI , Gibbons AE , Pereyra‐Bonnet F , Silvestre P , González‐Bulnes A
Published: December 2010

Contents

The aim of the study was to assess the effects of superovulatory treatment (multiple FSH‐dose vs single‐shot FSH treatment) and seasonality on embryo yields in fine‐wool Merino ewes. Treatment based on multiple FSH‐dose consisted of 200 mg of FSH (Folltropin®) administered in seven decreasing doses. Single‐shot treatment consisted of a single dose of 70 mg of FSH + eCG. In ewes treated with multiple FSH doses, number of recovered embryos was higher (6.0 ± 0.5 vs 3.5 ± 1.0), while non‐fertilization rate was lower (12.8 ± 3.9 vs 40.3 ± 9.5) during the breeding season when compared to the non‐breeding season (p < 0.05); although similar values of recovered Grades 1–2 embryos were observed between seasons. During the breeding season, proportion of responding ewes (98.1 vs 57.1%), ovulation rate (13.9 ± 0.8 vs 3.2 ± 1.2), recovered structures (7.9 ± 0.6 vs 1.7 ± 0.7), total recovered embryos (6.0 ± 0.5 vs 1.2 ± 0.6) and good‐quality embryos (5.1 ± 0.5 vs 0.9 ± 0.6) were higher for the multiple FSH‐dose treatment than for the single‐shot protocol. In a similar way, in the non‐breeding season, ovulation rate (11.3 ± 1.8 vs 6.0 ± 1.1) and recovered structures (6.6 ± 1.2 vs 2.7 ± 0.6) were higher for the multiple FSH injections protocol than those for the single‐shot treatment, resulting in higher recovered Grades 1–2 embryos (3.2 ± 0.9 vs 1.4 ± 0.5). Current results indicate that seasonal anestrus affected embryo yields when applying multiple FSH‐dose superovulatory treatment in Merino ewes, by decreasing the number of recovered embryos although the number of recovered good‐quality embryos was not affected. During both seasons, multiple FSH injections produced higher ovarian response and number of viable embryos than the single‐shot treatment.
The Role of Oocyte‐Secreted Factors GDF9 and BMP15 in Follicular Development and Oogenesis
Authors: Paulini Fernanda , Melo Eduardo O.
Published: December 2010

Contents

Ovarian physiology is controlled by endocrine and paracrine signals, and the transforming growth factor β (TGFβ) superfamily has a pivotal role in this control. The Bone morphogenetic protein 15 (BMP15) and Growth differentiation factor 9 (GDF9) genes are relevant members of the TGFβ superfamily that encode proteins secreted by the oocytes into the ovarian follicles. Through a paracrine signalling pathway, these factors induce the follicular somatic cells to undergo mitosis and differentiation during follicular development. These events are controlled by a mutually dependent and coordinated fashion during the formation of the granulosa cell layers. Many studies have contributed to our knowledge concerning the paracrine factors acting within the follicular environment, especially regarding GDF9 and BMP15. We aimed to review the relevant contributions of these two genes to animal reproductive physiology.
Retroperitoneal laparoscopic anatrophic nephrolithotomy for large staghorn calculi
Authors: Zhou Linyu , Xuan Qiang , Wu Bin , Xiao Jun , Dong Xiaocheng , Huang Tao , Chen Hao , Zhu Yuping , Wu Kui
Published: December 2010

Objectives:  Treatment of staghorn calculus is challenging. We evaluated the feasibility and efficacy of the retroperitoneal laparoscopic approach for the management of large staghorn renal calculi.

Methods:  Patients with staghorn renal calculi unsuitable for percutaneous nephrolithotomy were analyzed. They underwent retroperitoneal laparoscopic anatrophic nephrolithotomy, involving control of the renal artery, stone removal through a nephrotomy incision on the Brodel's line and closure with continuous sutures.

Results:  A total of 11 patients with renal stones were included in the present study. Mean patient age was 55 years (range 42–68) and stone size was 52 mm (range 43–61). Warm ischemia time and operative duration were 31 (range 23–38) and 139 min (range 105–160), respectively. No blood transfusion was needed during or after operation. An 8‐mm residual calculus remained in the lower calyces in one patient who was successfully treated by using shock wave lithotripsy. Intravenous pyelogram after surgery showed a functional corresponding renal unit, with an improvement in obstruction in all patients.

Conclusions:  Retroperitoneal laparoscopic technique can be applied for patients who are candidates for anatrophic nephrolithotomy. Larger studies with a longer follow up are needed to confirm these findings.
Risk factors for overactive bladder in the elderly population: A community‐based study with face‐to‐face interview
Authors: Ikeda Yoshihiro , Nakagawa Haruo , Ohmori‐Matsuda Kaori , Hozawa Atsushi , Masamune Yayoi , Nishino Yoshikazu , Kuriyama Shinichi , Ohnuma Tetsutaro , Tsuji Ichiro , Arai Yoichi
Published: December 2010

Objectives:  The aim of this study was to measure the prevalence of and risk factors for overactive bladder (OAB) in the elderly.

Methods:  A cross‐sectional study of elderly subjects was conducted by analyzing data from a community‐based Comprehensive Geriatric Assessment on people aged 70 years or older. Trained interviewers performed face‐to‐face interviews for the assessment of urological symptoms. OAB definition was based on urgency and eight or more episodes of urination per day. The subjects completed a self‐administered questionnaire including lifestyle evaluation, Geriatric Depression Scale, Mini‐Mental Status Examination and medical history. Brachial‐ankle pulse wave velocity was recorded to assess atherosclerotic disease. The analysis included 833 subjects, after the exclusion of 115 subjects who provided insufficient information.

Results:  Based on the definition of OAB, 153 subjects (18.4%) were identified as having OAB. Univariate analysis showed a significant association between OAB and depressive symptoms. Multivariate analysis showed that the risk of having OAB was significantly higher in subjects with depressive symptoms, current drinkers, and overweight subjects with odds ratios of 2.37 (1.60–3.52, 95% confidence interval), 1.65 (1.04–2.62), and 1.51 (1.02–2.24), respectively.

Conclusions:  This is the first report to show an association between OAB and depressive symptoms and alcohol intake in an epidemiological study of elderly people. The reasons for these correlations remain unclear, but should be the foci of future OAB studies.
Exercise impacts brain‐derived neurotrophic factor plasticity by engaging mechanisms of epigenetic regulation
Authors: Gomez‐Pinilla F. , Zhuang Y. , Feng J. , Ying Z. , Fan G.
Published: December 2010

We have evaluated the possibility that the action of voluntary exercise on the regulation of brain‐derived neurotrophic factor (BDNF), a molecule important for rat hippocampal learning, could involve mechanisms of epigenetic regulation. We focused the studies on the Bdnf promoter IV, as this region is highly responsive to neuronal activity. We have found that exercise stimulates DNA demethylation in Bdnf promoter IV, and elevates levels of activated methyl‐CpG‐binding protein 2, as well as BDNF mRNA and protein in the rat hippocampus. Chromatin immunoprecipitation assay showed that exercise increases acetylation of histone H3, and protein assessment showed that exercise elevates the ratio of acetylated : total for histone H3 but had no effects on histone H4 levels. Exercise also reduces levels of the histone deacetylase 5 mRNA and protein implicated in the regulation of the Bdnf gene [N.M. Tsankova et al. (2006)Nat. Neurosci., 9, 519–525], but did not affect histone deacetylase 9. Exercise elevated the phosphorylated forms of calcium/calmodulin‐dependent protein kinase II and cAMP response element binding protein, implicated in the pathways by which neural activity influences the epigenetic regulation of gene transcription, i.e. Bdnf. These results showing the influence of exercise on the remodeling of chromatin containing the Bdnf gene emphasize the importance of exercise on the control of gene transcription in the context of brain function and plasticity. Reported information about the impact of a behavior, inherently involved in the daily human routine, on the epigenome opens exciting new directions and therapeutic opportunities in the war against neurological and psychiatric disorders.
Bcl‐2 homology domain 3‐only proteins Puma and Bim mediate the vulnerability of CA1 hippocampal neurons to proteasome inhibition in vivo
Authors: Tsuchiya Takuro , Bonner Helena P. , Engel Tobias , Woods Ina , Matsushima Satoshi , Ward Manus W. , Taki Waro , Henshall David C. , Concannon Caoimhín G. , Prehn Jochen H. M.
Published: December 2010

Bcl‐2 homology domain 3 (BH3)‐only proteins are pro‐apoptotic Bcl‐2 family members that play important roles in upstream cell death signalling during apoptosis. Proteasomal stress has been shown to contribute to the pathology of cerebral ischaemia and many neurodegenerative disorders. Here we explored the contribution of BH3‐only proteins in mediating proteasome‐inhibition‐induced apoptosis in the murine brain in vivo. Stereotactic intrahippocampal microinjection of the selective proteasome inhibitor epoxomicin (2.5 nmol) induced a delayed apoptosis within only the CA1 hippocampal neurons and not neurons within the CA3 or dentate gyrus regions, a selective vulnerability similar to that seen during ischaemia. This injury developed over a time‐course of 3 days and was characterized by positive terminal deoxynucleotidyl transferase dUTP nick end labelling staining and nuclear condensation. Previous work from our laboratory has identified the BH3‐only protein p53‐upregulated mediator of apoptosis (Puma) as mediating proteasome‐inhibition‐induced apoptosis in cultured neural cells. Genetic deletion of puma reduced the number of terminal deoxynucleotidyl transferase dUTP nick end labelling‐positive cells within the CA1 following epoxomicin microinjection but it did not provide a complete protection. Subsequent studies identified the BH3‐only protein Bim as also being upregulated during proteasome inhibition in organotypic hippocampal slice cultures and after epoxomicin treatment in vivo. Interestingly, the genetic deletion of bim also afforded significant neuroprotection, although this protection was less pronounced. In summary, we demonstrate that the BH3‐only proteins Puma and Bim mediate the delayed apoptosis of CA1 hippocampal neurons induced by proteasome inhibition in vivo, and that either BH3‐only protein can only partly compensate for the deficiency of the other.
The reliability and validity of the Danish Draft Board Cognitive Ability Test: Børge Prien’s Prøve
Authors: TEASDALE THOMAS W. , HARTMANN PETER V.W. , PEDERSEN CHRISTOFFER H. , BERTELSEN METTE
Published: December 2010

Teasdale, T.W., Hartmann, P.V.W., Pedersen, C.H. & Bertelsen, M. (2011). The reliability and validity of the Danish Draft Board Cognitive Ability Test: Børge Prien’s Prøve. Scandinavian Journal of Psychology 52, 126–130.

The Danish Draft Board has used the same test for assessing general cognitive ability, the Børge Prien’s Prøve (BPP), for over 50 years during which time all men on reaching the age of 18 become liable for conscription. Data from the test has, over the decades, been used in numerous and wide‐ranging research studies. Nonetheless, owing to the special circumstances of its administration, some psychometric properties, which are generally assessed for psychological tests, have not previously been investigated for the BPP. First, since the test is only used at the assessment phase, retesting with the BPP occurs only rarely and under exceptional circumstances. Therefore, its Test‐Retest reliability has hitherto not been documented. Second, questions have often been raised as to whether the validity of the BPP is undermined by either a lack of motivation and under‐performing among some of the men taking the test, being, as they are, compelled to do so, and/or by gradual obsolescence of the test over the decades of its use. We here present findings from three new studies to show that (a) the BPP has a satisfactory Test‐Retest reliability, r = 0.77, (b) BPP test scores are not positively associated with expressed attitude to being called upon to serve conscription and (c) the correlation between the BPP and a measure of educational level has remained stable (at about 0.5) through the last two decades. Taken together these three findings further support the continuing value of the BPP in research relating to cognitive ability.
The Future of Private Equity
Authors: Lerner Josh
Published: December 2010

After a period of robust growth, the private equity industry has experienced a marked decline. In the wake of the 2008 economic crisis, the future of the venture and buyout industries seems unclear. This speech discusses four possible scenarios for the future of the private equity industry by examining the short‐ and long‐run determinants of private equity supply and demand. Possible scenarios include Recovery, Back to the Future, The Limited Partners' Desertion, and A Broken Industry. Although support is given for each of the scenarios, a clear prediction for the future remains difficult. The future of the private equity market is likely to be the subject of debate for some time to come.
Development and budding in the oozooids of Polyclinum aurantium (a colonial ascidian) (Protochordata)*
Authors: Nakauchi Mitsuaki
Published: December 2010

The life history of oozooids of a polyclinid ascidian, Polyclinum aurantium was studied by rearing them in small tanks. A newly metamorphosed zooid has four rows of stigmata, and lacks a postabdomen. Three (or four) new stigmatal rows are added to the original ones during oozooid growth; this phenomenon is exceptional in polyclinid ascidians. The post‐abdomen appears about 20 days after metamorphosis and grows rapidly. Budding occurs 40‐70 days after metamorphosis. Buds of three kinds are formed: one thoracic bud (“mother zooid”), one abdominal bud, and five to eight postabdominal buds. Both in formation of new stigmatal rows in the oozooid and in the mode of budding, Polyclinum and Sidneioides are alike, and they are different from other polyclinids. Budding in ascidinas is discussed from the viewpoint of its biological significance.,
Growth in Northwest Atlantic Harp seals Phoca groenlandica
Authors: Innes S. , Stewart R. E. A. , Lavigne D. M.
Published: December 2010

Morphometric data were collected from 204 Northwest Atlantic Harp seals aged one month and older sampled between 1976 and 1979. Length as a function of age gave the most precise measure of body size. Lean body (core) weight and total body weight were more variable measures of growth. Weight of blubber with skin attached (sculp weight) and blubber thickness exhibited greatest variation with age and (or) sampling date. There was no evidence of sexual dimorphism in any growth parameter.

Several Richards‐type models provided adequate descriptions of Harp seal growth. The growth curve of body length as a function of age suggested a larger size of zero age‐class animals and a higher absolute growth rate than reported for animals from the same stock during the 1950s. These results are discussed in relation to the observed changes in mean age of maturity which accompanied the decline in stock abundance from the 1950s to the 1970s.
Influence of pectoral fin shape on thrust and drag in labriform locomotion
Authors: Blake R. W.
Published: December 2010

A simple hydromechanical model of the influence of pectoral fin geometry on thrust is developed. The model contains a shape factor (analogous to that employed by Weis‐Fogh (1973) in his analysis of the influence of wing shape on normal hovering in insects and hummingbirds), which is calculated for various hypothetical fin shapes and the pectoral fins of Pterophyllum eimekei and Trichogaster tricopterus. The model predicts that fish which swim in the drag‐based labriform mode are more likely to have triangular fins than square or rectangular ones, and this is generally the case.

The influence of pectoral fin shape on labriform locomotion is investigated further experimentally, using dead fish and a model Angelfish fitted with various model pectoral fin shapes (circular disc, square, rectangular or triangular fins of equivalent wetted surface area). Frictional and pressure drag determinations were made with the model fins attached to the end of a narrow spar (so that the flow around them would not influence that around the body) with the fins orientated either parallel (for frictional drag determinations) or “broadside on” (for pressure drag determinations) to the incident flow.

Values for the frictional drag of the various fin types were essentially the same for any given terminal velocity. The pressure drag of square and rectangular fins is about 14% less than that of triangular fins of the same area over a range of terminal velocities. When the fins are directly attached to the sides of the model fish and orientated “broadside on” to the flow the total drag force is higher (for any given value of the terminal velocity) than the values measured when the fins were placed, with the same orientation, on the ends of a spar. The difference is probably due to “interference drag” produced by the fins, due to the effect of the vorticity which they shed into the flow over the body.
Visual versus climatic selection of shell banding in the landsnail Theba pisana in Israel
Authors: Heller Joseph
Published: December 2010

The helicid landsnail Theba plsana in Israel has a four‐banded shell in which five morphs occur: 1234, 0234, 0034, 0004 and 0000. Upon each of these bands dark, delicate bandlets may sometimes appear.

To examine whether (as is claimed in literature) in the north, where it is more humid, shells are darker than in the south, where it is more arid, a 160‐km‐long north (humid) to south (arid) transect was made along the coastal plain, and 32 samples were collected. Each sample was scored for relative frequency of the darkest morph, the relative frequency of effectively banded shells and the mean number of bands in the sample. In addition, the relative frequency of shells with a pale third band, and of shells with many bandlets (four or more) in the third band was scored. No evidence was found that snails in the north are darker than those in the south.

In contrast, however, four of the five variables scored in each snail showed a very highly significant association with the extent of perennial vegetation at the locality. The fifth variable, namely the relative frequency of shells with many bandlets, showed a significant association only in the southernmost part of the transect.

Dark shells are cryptic and are probably favoured by visual selection; light snails are conspicuous (but for the exceptional case when they occur among the white flowers of the Retama shrub), but are favoured by climatic selection. The environmental factor which ultimately decides between these two contrasting selective forces is the nature of the vegetation: by shielding snails from solar radiation, perennial vegetation may enable the snails to be cryptic, i.e. dark, without suffering overheating by solar radiation. Annual vegetation, in contrast, does not offer such shading so that snails here must be light‐coloured.
Estimates of the bending moments exerted by the lumbar and abdominal muscles of some mammals
Authors: Alexander R. Mcn. , Jayes A. S.
Published: December 2010

The abdominal and lumbar muscles of rat, ferret, dog and hare have been measured and their arrangement noted. Rough calculations have been made of the flexor or extensor moment each muscle can exert, about a mid‐lumbar intervertebral joint. Comparisons are made with previously published data on man.
Natural hybridization and gene introgression between Xenopus gilli and Xenopus laevis laevis (Anura: Pipidae)
Authors: Kobel H. R. , Pasquier L. Du , Tinsley R. C.
Published: December 2010

The rare Xenopus gilli is restricted to the southern tip of South Africa where it occurs sympatrically with the much more numerous Xenopus laevis laevis. Specimens of intermediate phenotype are occasionally found on the Cape Flats, and a sample of these was examined for evidence of hybridization. Serological, immunological and reproductive studies showed that one female was an F1 hybrid between X. gilli and X. I. laevis; a second female, which exhibited one X. gilli specific serum protein amongst otherwise laevis characters, demonstrated introgression of gilli genes into the laevis species. Cross‐breeding between the two sympatric Xenopus species represents a danger for the survival of the already‐vulnerable X. gilli. The genetic behaviour of hybrids also carries implications of evolutionary potential, on the one hand creating gene flow between species, and on the other hand capable of generating new polyploid hybrid species. There is evidence that allopolyploidy has been an important process in the evolution of Xenopus.
Effect of food or water deprivation on circulating levels of pituitary, thyroid and adrenal hormones and on glucose and electrolyte concentrations in domestic ducks (Anas platyrhynchos)
Authors: Harvey S. , Klandorf H. , Phillips J. G.
Published: December 2010

In the natural environment, birds may frequently experience periods of starvation or dehydration, as a result of restrictions in food or water availability, temperature extremes, ecological competition and some migratory, sexual and nesting behaviour. In this paper the involvement of pituitary (growth hormone and luteinizing hormone), thyroid (thyroxine and triiodothyronine) and adrenal (corticosterone) hormones in the birds homeostatic response to these stresses has been investigated in ducks (Anas platyrhynchos) deprived of food or water for up to 36 h and in ducks additionally stressed by prior adaptation to hyper‐osmotic drinking water and/or acutely orally loaded with crude North Sea oil. Variations in the peripheral plasma concentration of these hormones during food or water deprivation have also been correlated with stress induced alterations in body and organ weights and with accompanying changes in circulating sodium, potassium and glucose levels; their physiological roles during stress are discussed.
Differing resistance of various mollusc shell materials to simulated whelk attack
Authors: Gabriel JulieM.
Published: December 2010

The combination of an inner layer of nacre and an outer layer of simple prisms is thought to be phylogenetically the oldest molluscan shell type. Although nacre is very strong it is not as widely used as crossed‐lamellar shell. Factors other than tensile strength or modulus of elasticity, such as resistance to abrasion or chemical attack, may have been important in the evolution of other shell types. Nacreous shell is shown to be less resistant than prismatic or crossed‐lamellar shell to simulated components of whelk attack. Homogeneous shell is more resistant than other shell types to abrasion. A relationship between life‐style and shell microstructure is suggested.
Dwindling resources and the social behaviour of Capybaras, (Hydrochoerus hydrochaeris) (Mammalia)
Authors: Macdonald D. W.
Published: December 2010

Capybaras, Hydrochoerus hydrochaeris, were studied in the Venezuelan llanos during the peak of a dry season. As surface water and associated resources dwindled the rodents’group sizes, activity pattern and social behaviour were studied. Capybara group sizes varied from habitat to habitat in a way which seemed explicable by the pattern of the dwindling water supply. Other behaviour described includes communal suckling of young and collaborative defence against predators.
Ultrastructure of spermatogenesis in Phreodrilus (Phreodrilidae, Oligochaeta, Annelida)
Authors: Jamieson B. G. M.
Published: December 2010

Phreodrilus has a free filamentous spermatozoon of an advanced type, characteristic of the Oligochaeta but with distinctive features. As in the Lumbricidae and Megascolecidae the primary acrosome vesicle, enclosing the subvesicular space (secondary acrosome vesicle) is withdrawn deeply into the acrosome tube and the nucleus is non‐spiral. The midpiece has six mitochondria as in these families, in the Lumbriculidae and in some Tubificidae and its radial septa are spiral as in the Lumbriculidae and Enchytraeidae. Among peculiar features are the great elongation of the acrosome and midpiece, the long basal acrosomal chamber distal to the axial rod and primary vesicle and spiralling (possibly transient) of the peripheral elements of the flagellar axoneme. Spermatogenesis accords with that in other oligochaetes but an anomalous and hither unknown type of sperm morula is present in addition to typical morulae. It shows multiplication of each cytophore‐attached spermato‐gonium to give many spermatids on each zonula collaris and more than 400 cells in a morula.
Sequential mobilization of marrow fat in the Impala (Aepyceros melampus) and analysis of condition of Wild dog (Lycaon pictus) prey
Authors: Reich Allen
Published: December 2010

Mobilization of bone marrow fat in the fore and hindlimbs of the Impala (Aepycevos melampus) was shown to be sequential in nature, with proximal bones showing distinct fat loss before medial and distal bones were mobilized. There are indications that medial bone marrow fat is mobilized at a greater rate than that of the distal bone in both the fore and hindlimbs, thus indicating sequential mobilization proceeding distally from the proximal bone. Further evidence suggests that bones in the hindlimb are mobilizing fat at a faster rate than comparable bones in the forelimb. The degree of marrow fat loss shows that Wild dogs (Lycaon pictus) in the Kruger National Park, South Africa are preying on Impala which exhibit both high and low marrow fat values, thereby indicating predation on both sick and relatively healthy animals. The presence of relatively healthy animals in the Wild dog diet is seen as a direct result of the high density of cover and consequent low visibility in the Kruger National Park.
Prey of the Cape clawless otter (Aonyx capensis) in the Tsitsikama Coastal National Park, South Africa
Authors: Van Der Zee D.
Published: December 2010

Food of Cape clawless otters was estimated by means of faeces (spraint) analysis, using frequency of occurrence, as well as analysis by weight. The two methods were combined to yield a more accurate estimate of numbers and weight of prey taken. Availability of prey was estimated from sampling in two areas in the marine inter and subtidal zones. Estimates of consumption were combined with estimates of availability to yield an index of selection. Two species of crabs, octopus and suckerfish together made up about 81% of the numbers (86% of the weight) of prey taken, while the other 19% consisted of at least 30 other species. The relative merits and problems of frequency and weight analysis of faeces, as related to this species, are discussed. It was concluded that otters are opportunistic feeders with a good ability to capitalize on available prey, but along the Tsitsikama coast this was also due to the fact that no change in hunting method (used inland) was necessary.