bluuebunny/crossref_metadata_2025 huggingface dataset:
Activation of BKCa channels via cyclic AMP‐ and cyclic GMP‐dependent protein kinases by eugenosedin‐A in rat basilar artery myocytes
Authors: Wu B‐N , Chen C‐F , Hong Y‐R , Howng S‐L , Lin Y‐L , Chen I‐J
Published: August 2007

Background and purpose:

The study investigated whether eugenosedin‐A, a 5‐hydroxytryptamine and α/β adrenoceptor antagonist, enhanced delayed‐rectifier potassium (KDR)‐ or large‐conductance Ca2+‐activated potassium (BKCa)‐channel activity in basilar artery myocytes through cyclic AMP/GMP‐dependent and ‐independent protein kinases.

Experimental approach:

Cerebral smooth muscle cells (SMCs) were enzymatically dissociated from rat basilar arteries. Conventional whole cell, perforated and inside‐out patch‐clamp electrophysiology was used to monitor K+‐ and Ca2+‐channel activities.

Key results:

Eugenosedin‐A (1 μ
M) did not affect the KDR current but dramatically augmented BKCa channel activity in a concentration‐dependent manner. Increased BKCa current was abolished by charybdotoxin (ChTX, 0.1 μ
M) or iberiotoxin (IbTX, 0.1 μ
M), but not affected by a small‐conductance KCa blocker (apamin, 100 μ
M). BKCa current activation by eugenosedin‐A was significantly inhibited by an adenylate cyclase inhibitor (SQ 22536, 10 μ
M), a soluble guanylate cyclase inhibitor (ODQ, 10 μ
M), competitive antagonists of cAMP and cGMP (Rp‐cAMP, 100 μ
M and Rp‐cGMP, 100 μ
M), and cAMP‐ and cGMP‐dependent protein kinase inhibitors (KT5720, 0.3 μ
M and KT5823, 0.3 μ
M). Eugenosedin‐A reversed the inhibition of BKCa current induced by the protein kinase C activator, phorbol myristyl acetate (PMA, 0.1 μ
M). Eugenosedin‐A also prevented BKCa current inhibition induced by adding PMA, KT5720 and KT5823. Moreover, eugenosedin‐A reduced the amplitude of voltage‐dependent L‐type Ca2+ current (ICa,L), but without modifying the voltage‐dependence of the current.

Conclusions and implications:

Eugenosedin‐A enhanced BKCa currents by stimulating the activity of cyclic nucleotide‐dependent protein kinases. Physiologically, this activation would result in the closure of voltage‐dependent calcium channels and thereby relax cerebral SMCs.

British Journal of Pharmacology (2007) 152, 374–385; doi:10.1038/sj.bjp.0707406; published online 13 August 2007
Transient allodynia pain models in mice for early assessment of analgesic activity
Authors: Gil D W , Cheevers C V , Donello J E
Published: August 2007

Background and purpose:

The most common preclinical models of neuropathic pain involve surgical ligation of sensory nerves, which is especially difficult in mice. Transient models of chemically sensitized allodynia are potentially useful for rapidly characterizing the analgesic profile of compounds and conducting mechanistic studies.

Experimental approach:

Increasing doses of NMDA, sulprostone (an EP1/EP3 prostaglandin receptor agonist) or phenylephrine (an α1 adrenoceptor agonist) were injected intrathecally (i.t.) or i.p., and animals were subsequently assessed for allodynia. The effects of receptor antagonists and analgesic compounds on allodynia were also assessed.

Key results:

A comparison of total body doses that cause allodynia following spinal or systemic administration indicated that NMDA induces allodynia in the spinal cord while sulprostone and phenylephrine act through a peripheral mechanism. Inhibition of the allodynia with receptor antagonists indicated that each agent induces allodynia by a distinct mechanism. The three models were benchmarked using compounds known to be active in neuropathic pain patients and nerve injury animal models, including gabapentin, amitriptyline and clonidine.

Conclusions and implications:

These transient allodynia models are a useful addition to the toolbox of preclinical pain models. They are simple, rapid and reproducible, and will be especially useful for characterizing the pain phenotype of knockout mice.

British Journal of Pharmacology (2008) 153, 769–774; doi:10.1038/sj.bjp.0707412; published online 13 August 2007
NPC1L1 (Niemann–Pick C1-like 1) mediates sterol-specific unidirectional transport of non-esterified cholesterol in McArdle-RH7777 hepatoma cells
Authors: Brown J. Mark , Rudel Lawrence L. , Yu Liqing
Published: August 2007

Recent evidence suggests that NPC1L1 (Niemann–Pick C1-like 1) is critical for intestinal sterol absorption in mice, yet mechanisms by which NPC1L1 regulates cellular sterol transport are lacking. In the study we used a McArdle-RH7777 rat hepatoma cell line stably expressing NPC1L1 to examine the sterol-specificity and directionality of NPC1L1-mediated sterol transport. As previously described, cholesterol-depletion-driven recycling of NPC1L1 to the cell surface facilitates cellular uptake of non-esterified (free) cholesterol. However, it has no impact on the uptake of esterified cholesterol, indicating free sterol specificity. Interestingly, the endocytic recycling of NPC1L1 was also without effect on β-sitosterol uptake, indicating that NPC1L1 can differentiate between free sterols of animal and plant origin in hepatoma cells. Furthermore, NPC1L1-driven free cholesterol transport was unidirectional, since cellular cholesterol efflux to apolipoprotein A-I, high-density lipoprotein or serum was unaffected by NPC1L1 expression or localization. Additionally, NPC1L1 facilitates mass non-esterified-cholesterol uptake only when it is located on the cell surface and not when it resides intracellularly. Finally, NPC1L1-dependent cholesterol uptake required adequate intracellular K+, yet did not rely on intracellular Ca2+, the cytoskeleton or signalling downstream of protein kinase A, protein kinase C or pertussis-toxin-sensitive G-protein-coupled receptors. Collectively, these findings support the notion that NPC1L1 can selectively recognize non-esterified cholesterol and promote its unidirectional transport into hepatoma cells.
Pharmacological chaperoning: two ‘hits’ are better than one
Authors: Skach William R.
Published: August 2007

Protein folding disorders comprise a rapidly growing group of diseases that involve virtually every organ system and affect individuals of all ages. Their principal pathology is the inability of a protein to acquire or maintain its physiological three-dimensional structure. In cells, this generally results in one of three outcomes: accumulation of misfolded protein aggregates, cell death, or recognition by cellular quality control machinery and rapid degradation. Large-scale screening efforts to identify and design small molecules that either repair the folding defect or enable the protein to escape degradation have been encouraging. However, most compounds identified to date restore only a small fraction of molecules to the normal folding pathway, and hence are relatively poor therapeutic candidates. Results published by Wang et al. in this issue of the Biochemical Journal show that, for mutant forms of two ABC (ATP-Binding-Cassette) transporters, P-glycoprotein and CFTR (cystic fibrosis transmembrane conductance regulator), modest correction of trafficking by single agents can be additive when multiple compounds are used in combination. These findings raise the intriguing possibility that corrector molecules acting at different steps along the folding pathway might provide a multidrug approach to human protein folding disorders.
New US Trade Policy: A Turning Point?
Authors: Jorge Maria Fabiana
Published: August 2007

Trade agreements on intellectual property (IP) became a useful tool for patent holders to increase their exclusive marketing rights around the world. Bilateral agreements have gradually increased the standards of protection beyond those of the TRIPS agreement creating a growing imbalance between the rights of IP holders on one side and those of consumers and the generic industry, on the other. After the Democratic Party became the majority party in the US Congress in January 2007, the new leadership of the Ways and Means Committee of the House of Representatives forced the US Trade Representative to reopen the Free Trade Agreements (FTAs) with Peru, Panama and Colombia, the ratification of which was pending, and introduced substantial changes to the final texts to reduce the negative effects on access to medicines posed by the original agreements. This seems to mark a significant turning point but all will depend on how these governments implement the FTAs into their national laws and on whether they actually take advantage of this opportunity. Will other governments follow the leadership shown by the Ways and Means Committee?
Polaron melting and ordering as key mechanisms for colossal resistance effects in manganites
Authors: Jooss Ch. , Wu L. , Beetz T. , Klie R. F. , Beleggia M. , Schofield M. A. , Schramm S. , Hoffmann J. , Zhu Y.
Published: August 2007

Polarons, the combined motion of electrons in a cloth of their lattice distortions, are a key transport feature in doped manganites. To develop a profound understanding of the colossal resistance effects induced by external fields, the study of polaron correlations and the resulting collective polaron behavior, i.e., polaron ordering and transition from polaronic transport to metallic transport is essential. We show that static long-range ordering of Jahn–Teller polarons forms a polaron solid which represents a new type of charge and orbital ordered state. The related noncentrosymmetric lattice distortions establish a connection between colossal resistance effects and multiferroic properties, i.e., the coexistence of ferroelectric and antiferromagnetic ordering. Colossal resistance effects due to an electrically induced polaron solid–liquid transition are directly observed in a transmission electron microscope with local electric stimulus applied
in situ
using a piezo-controlled tip. Our results shed light onto the colossal resistance effects in magnetic field and have a strong impact on the development of correlated electron-device applications such as resistive random access memory (RRAM).
Propagation of large concentration changes in reversible protein-binding networks
Authors: Maslov Sergei , Ispolatov I.
Published: August 2007

We study how the dynamic equilibrium of the reversible protein–protein-binding network in yeast
Saccharomyces cerevisiae
responds to large changes in abundances of individual proteins. The magnitude of shifts between free and bound concentrations of their immediate and more distant neighbors in the network is influenced by such factors as the network topology, the distribution of protein concentrations among its nodes, and the average binding strength. Our primary conclusion is that, on average, the effects of a perturbation are strongly localized and exponentially decay with the network distance away from the perturbed node, which explains why, despite globally connected topology, individual functional modules in such networks are able to operate fairly independently. We also found that under specific favorable conditions, realized in a significant number of paths in the yeast network, concentration perturbations can selectively propagate over considerable network distances (up to four steps). Such “action-at-a-distance” requires high concentrations of heterodimers along the path as well as low free (unbound) concentration of intermediate proteins.
Experimental validation of Haldane's hypothesis on the role of infection as an evolutionary force for Metazoans
Authors: Navas Alfonso , Cobas Guillermo , Talavera Miguel , Ayala Juan A. , López Juan A. , Martínez José L.
Published: August 2007

A common drawback in evolutionary science is the fact that the evolution of organisms occurs in geological timing, completely out of the time scale of laboratory experimental work. For this reason, some relevant hypotheses on evolution of Metazoans are based on correlations more than on experimental data obtained for testing the robustness of those hypotheses. In the current work, we implement an experimental methodology to analyze the role of infections as a driving force in the evolution of Metazoans (Haldane's hypothesis). To that goal, we have used simple models of virulence with short reproduction times, large populations, and that are easily testable in the laboratory. Using the bacteriovirus nematode
Caenorhabditis elegans
as a model organism under evolution and their infection by the environmental opportunistic bacterial pathogen
Pseudomonas aeruginosa
as the selective force, we have demonstrated that bacterial infection selects an evolved nematode lineage resistant to infection, with changes in its respiration and capability of consuming novel food resources. Using an experimental approach, we show that infection is a selective force in the evolution of Metazoans as proposed earlier by Haldane.
von Hippel–Lindau binding protein 1-mediated degradation of integrase affects HIV-1 gene expression at a postintegration step
Authors: Mousnier Aurélie , Kubat Nicole , Massias-Simon Aurélie , Ségéral Emmanuel , Rain Jean-Christophe , Benarous Richard , Emiliani Stéphane , Dargemont Catherine
Published: August 2007

HIV-1 integrase, the viral enzyme responsible for provirus integration into the host genome, can be actively degraded by the ubiquitin–proteasome pathway. Here, we identify von Hippel–Lindau binding protein 1(VBP1), a subunit of the prefoldin chaperone, as an integrase cellular binding protein that bridges interaction between integrase and the cullin2 (Cul2)-based von Hippel–Lindau (VHL) ubiquitin ligase. We demonstrate that VBP1 and Cul2/VHL are required for proper HIV-1 expression at a step between integrase-dependent proviral integration into the host genome and transcription of viral genes. Using both an siRNA approach and Cul2/VHL mutant cells, we show that VBP1 and the Cul2/VHL ligase cooperate in the efficient polyubiquitylation of integrase and its subsequent proteasome-mediated degradation. Results presented here support a role for integrase degradation by the prefoldin–VHL–proteasome pathway in the integration–transcription transition of the viral replication cycle.
Information and Communication Technology and the Places Left Behind
1
Authors: Luger Michael I. , Maynard Nicholas C.
Published: August 2007

This article focuses on the critical role ICT policy design and implementation can play in developing a knowledge‐based economy in distressed US communities. Using a multiple case study research design, the study tests three hypotheses: (1) linkages among government, education and industry are a critical success factor for ICT interventions; (2) due to the long‐term nature of ICT, vision and leadership are also critical; and (3) investments in technology infrastructure must be part of a larger local planning process to succeed. These hypotheses are supported, but the strength of the article is in the details about how communities crafted unique responses to critical issues.
Non‐advertising alcohol promotions in licensed premises: does the Code of Practice ensure responsible promotion of alcohol?
Authors: JONES SANDRA C. , LYNCH MELISSA
Published: August 2007

Introduction and Aims. Binge drinking is a major public health issue in Australia, particularly among young people. There has been a considerable focus on alcohol advertising, among both researchers and policy makers, resulting in efforts to bring about some level of regulation of unacceptable advertising practices. However—despite the existence of a Code of Practice for Responsible Promotion of Liquor Products which provides ‘a framework of practices which are considered acceptable and reasonable’ for licensed premises—there are few, if any, data on the nature and extent of promotions which could arguably fall under either ‘acceptable’ or ‘unacceptable’ practices. Design and Methods. Over an 8‐week period we monitored promotions offered by licensed venues (pubs, bars and clubs) in the Wollongong central area. Seventeen venues were identified, and each venue was visited daily for 1 week. Trained research assistants took notes on all promotions/events in visited venues, including both manufacturer‐ and management‐initiated. Results. We identified a range of different types of promotions, including low cost and free drinks. Some of the promotions identified could be seen to have a positive public health impact, such as free food and free transport. However, the majority of promotions were of a nature likely to increase the likelihood of excessive drinking. Discussion and Conclusions. It is evident from this review that there are numerous examples of promotions which breach both the spirit and the letter of the Code. It is equally evident that the system for monitoring compliance with the Code is fundamentally inadequate.
Using population data to examine the prevalence and correlates of neonatal abstinence syndrome
Authors: BURNS LUCY , MATTICK RICHARD P.
Published: August 2007

The objective of this study was to determine the population prevalence and correlates of neonatal abstinence syndrome among neonates born to women on methadone, using a cross‐sectional analysis of linked population health data. A total of 2941 live births to women actively on methadone at delivery were analysed over an 11‐year period (1992–2002). Of these births, 796 neonates (27%) were diagnosed with an International Classification of Diseases‐9CM (ICD‐9CM) or International Classification of Diseases ICD‐10AM (ICD‐10AM) diagnosis related to neonatal withdrawal from exposure to opiates in utero (NAS). There were significant differences found between mothers whose neonates did and did not receive an International Classification of Diseases NAS‐related diagnosis. Mothers of neonates with a NAS‐related diagnosis had a higher number of previous pregnancies, were more likely to be indigenous, to smoke more heavily and were more likely to present for delivery unbooked. Neonates diagnosed with NAS were admitted to Special Care Nursery more often. NAS is diagnosed less frequently using International Classification of Diseases (ICD) codes than when using clinical scales measuring opiate‐related neonatal withdrawal. This suggests that NAS may be under‐represented in hospital morbidity databases that use ICD codes to quantify patient throughput and in some circumstances this may result from under‐detection of the condition. Future research should therefore seek to determine the validity of NAS recording in hospital morbidity databases reliant on the use ICD codes.
Alcohol consumption of Australian women: results from the Australian Longitudinal Study on Women's Health
Authors: CLEMENS SUSAN L. , MATTHEWS SHARON L. , YOUNG ANNE F. , POWERS JENNIFER R.
Published: August 2007

Introduction and Aims. Alcohol misuse is responsible for extensive personal harm and high societal costs. Research related specifically to women's alcohol consumption is important due to gender differences in clinical outcomes and disease progression. Design and Methods. This study examines longitudinal changes in the patterns of alcohol consumption associated with harm in the long term (chronic) and short term (acute) as defined by the Australian National Health and Medical Research Council. Results are presented for three age cohorts (18–23 years, 45–50 years and 70–75 years) using data from the Australian Longitudinal Study on Women's Health 1996–2003. Initial response rates for the study were 41%, 54% and 36% for the Younger, Mid‐aged and Older cohort, respectively. Results. The percentages of women that initiated usual weekly consumption in excess of 140 g of alcohol, designated as long‐term risky or high risk consumption, between surveys 1 and 2 were 2.7%, 2.1% and 1.7% (Younger, Mid‐aged and Older cohorts, respectively). Similarly, between surveys 1 and 2, 7.8% of younger women and 2.5% of mid‐aged women initiated consumption of 50 g of alcohol on one occasion at least weekly, placing them at risk of alcohol‐related harm in the short‐term weekly. Examining data across the three time‐points in the Younger cohort, 0.3% of women were at risk of alcohol‐related harm in the long term across all three time‐points, and 9.2% were at risk at one or two time‐points. The percentage of younger women at risk of alcohol‐related harm in the short term at least weekly was 3.4% at risk at all three time‐points and 24% at risk at one or two time‐points. Discussion and Conclusions. This study indicates that there is a small percentage of women who maintain levels of alcohol consumption associated with increased risk of morbidity and mortality over time, but a much larger proportion of women that drink at hazardous levels sporadically during the life course. Prevention efforts may need to target transient high‐risk alcohol consumers differently than consistently heavy alcohol consumers. Non‐response bias and attrition may have caused the prevalence of both entrenched and episodic heavy consumption to be underestimated.
Memory CD8+ T cells mediate antibacterial immunity via CCL3 activation of TNF/ROI+ phagocytes
Authors: Narni-Mancinelli Emilie , Campisi Laura , Bassand Delphine , Cazareth Julie , Gounon Pierre , Glaichenhaus Nicolas , Lauvau Grégoire
Published: August 2007

Cytolysis, interferon γ and tumor necrosis factor (TNF) α secretion are major effector mechanisms of memory CD8+ T cells that are believed to be required for immunological protection in vivo. By using mutants of the intracellular bacterium Listeria monocytogenes, we found that none of these effector activities is sufficient to protect against secondary infection with wild-type (WT) bacteria. We demonstrated that CCL3 derived from reactivated memory CD8+ T cells is required for efficient killing of WT bacteria. CCL3 induces a rapid TNF-α secretion by innate inflammatory mononuclear phagocytic cells (MPCs), which further promotes the production of radical oxygen intermediates (ROIs) by both MPCs and neutrophils. ROI generation is the final bactericidal mechanism involved in L. monocytogenes clearance. These results therefore uncover two levels of regulation of the antibacterial secondary protective response: (a) an antigen-dependent phase in which memory CD8+ T cells are reactivated and control the activation of the innate immune system, and (b) an antigen-independent phase in which the MPCs coordinate innate immunity and promote the bactericidal effector activities. In this context, CCL3-secreting memory CD8+ T cells are able to mediate “bystander” killing of an unrelated pathogen upon antigen-specific reactivation, a mechanism that may be important for the design of therapeutic vaccines.
Gas jet disruption mitigation studies on Alcator C-Mod and DIII-D
Authors: Granetz R.S. , Hollmann E.M. , Whyte D.G. , Izzo V.A. , Antar G.Y. , Bader A. , Bakhtiari M. , Biewer T. , Boedo J.A. , Evans T.E. , Hutchinson I.H. , Jernigan T.C. , Gray D.S. , Groth M. , Humphreys D.A. , Lasnier C.J. , Moyer R.A. , Parks P.B. , Reinke M.L. , Rudakov D.L. , Strait E.J. , Terry J.L. , Wesley J. , West W.P. , Wurden G. , Yu J.
Published: August 2007

High-pressure noble gas jet injection is a mitigation technique which potentially satisfies the requirements of fast response time and reliability, without degrading subsequent discharges. Previously reported gas jet experiments on DIII-D showed good success at reducing deleterious disruption effects. In this paper, results of recent gas jet disruption mitigation experiments on Alcator C-Mod and DIII-D are reported. Jointly, these experiments have greatly improved the understanding of gas jet dynamics and the processes involved in mitigating disruption effects. In both machines, the sequence of events following gas injection is observed to be quite similar: the jet neutrals stop near the plasma edge, the edge temperature collapses and large MHD modes are quickly destabilized, mixing the hot plasma core with the edge impurity ions and radiating away the plasma thermal energy. High radiated power fractions are achieved, thus reducing the conducted heat loads to the chamber walls and divertor. A significant (2 × or more) reduction in halo current is also observed. Runaway electron generation is small or absent. These similar results in two quite different tokamaks are encouraging for the applicability of this disruption mitigation technique to ITER.
Rab6 Regulates Both ZW10/RINT-1– and Conserved Oligomeric Golgi Complex-dependent Golgi Trafficking and Homeostasis
Authors: Sun Yi , Shestakova Anna , Hunt Lauren , Sehgal Siddharth , Lupashin Vladimir , Storrie Brian
Published: August 2007

We used multiple approaches to investigate the role of Rab6 relative to Zeste White 10 (ZW10), a mitotic checkpoint protein implicated in Golgi/endoplasmic reticulum (ER) trafficking/transport, and conserved oligomeric Golgi (COG) complex, a putative tether in retrograde, intra-Golgi trafficking. ZW10 depletion resulted in a central, disconnected cluster of Golgi elements and inhibition of ERGIC53 and Golgi enzyme recycling to ER. Small interfering RNA (siRNA) against RINT-1, a protein linker between ZW10 and the ER soluble N-ethylmaleimide-sensitive factor attachment protein receptor, syntaxin 18, produced similar Golgi disruption. COG3 depletion fragmented the Golgi and produced vesicles; vesicle formation was unaffected by codepletion of ZW10 along with COG, suggesting ZW10 and COG act separately. Rab6 depletion did not significantly affect Golgi ribbon organization. Epistatic depletion of Rab6 inhibited the Golgi-disruptive effects of ZW10/RINT-1 siRNA or COG inactivation by siRNA or antibodies. Dominant-negative expression of guanosine diphosphate-Rab6 suppressed ZW10 knockdown induced-Golgi disruption. No cross-talk was observed between Rab6 and endosomal Rab5, and Rab6 depletion failed to suppress p115 (anterograde tether) knockdown-induced Golgi disruption. Dominant-negative expression of a C-terminal fragment of Bicaudal D, a linker between Rab6 and dynactin/dynein, suppressed ZW10, but not COG, knockdown-induced Golgi disruption. We conclude that Rab6 regulates distinct Golgi trafficking pathways involving two separate protein complexes: ZW10/RINT-1 and COG.
Atg18 Regulates Organelle Morphology and Fab1 Kinase Activity Independent of Its Membrane Recruitment by Phosphatidylinositol 3,5-Bisphosphate
Authors: Efe Jem A. , Botelho Roberto J. , Emr Scott D.
Published: August 2007

The lipid kinase Fab1 governs yeast vacuole homeostasis by generating PtdIns(3,5)P2on the vacuolar membrane. Recruitment of effector proteins by the phospholipid ensures precise regulation of vacuole morphology and function. Cells lacking the effector Atg18p have enlarged vacuoles and high PtdIns(3,5)P2levels. Although Atg18 colocalizes with Fab1p, it likely does not directly interact with Fab1p, as deletion of either kinase activator—VAC7 or VAC14—is epistatic to atg18Δ: atg18Δvac7Δ cells have no detectable PtdIns(3,5)P2. Moreover, a 2xAtg18 (tandem fusion) construct localizes to the vacuole membrane in the absence of PtdIns(3,5)P2, but requires Vac7p for recruitment. Like the endosomal PtdIns(3)P effector EEA1, Atg18 membrane binding may require a protein component. When the lipid requirement is bypassed by fusing Atg18 to ALP, a vacuolar transmembrane protein, vac14Δ vacuoles regain normal morphology. Rescue is independent of PtdIns(3,5)P2, as mutation of the phospholipid-binding site in Atg18 does not prevent vacuole fission and properly regulates Fab1p activity. Finally, the vacuole-specific type-V myosin adapter Vac17p interacts with Atg18p, perhaps mediating cytoskeletal attachment during retrograde transport. Atg18p is likely a PtdIns(3,5)P2“sensor,” acting as an effector to remodel membranes as well as regulating its synthesis via feedback that might involve Vac7p.
Enhancement of Amygdaloid Neuronal Dendritic Arborization by Fresh Leaf Juice of Centella asiatica (Linn) during Growth Spurt Period in Rats
Authors: Mohandas Rao K. G. , Muddanna Rao S. , Gurumadhva Rao S.
Published: August 2007

Centella asiatica (CeA) is a creeping herb, growing in moist places in India and other Asian Countries. Ayurvedic system of medicine, an alternate system of medicine in India, uses leaves of CeA for memory enhancement. Here, we have investigated the role of CeA fresh leaf juice treatment during growth spurt period of rats on dendritic morphology of amygdaloid neurons, one of the regions concerned with learning and memory. The present study was conducted on neonatal rat pups. The rat pups (7‐days‐old) were fed with 2, 4 and 6 ml/kg body of fresh leaf juice of CeA for 2, 4 and 6 weeks. After the treatment period, the rats were killed, brains removed and amygdaloid neurons impregnated with Silver nitrate (Golgi staining). Amygdaloid neurons were traced using camera lucida and dendritic branching points (a measure of dendritic arborization) and intersections (a measure dendritic length) quantified. These data were compared with those of age‐matched control rats. The results showed a significant increase in dendritic length (intersections) and dendritic branching points along the length of dendrites of the amygdaloid neurons of rats treated with 4 and 6 ml/kg body weight/day of CeA for longer periods of time (i.e. 4 and 6 weeks). We conclude that constituents/active principles present in CeA fresh leaf juice has neuronal dendritic growth stimulating property; hence it can be used for enhancing neuronal dendrites in stress and other neurodegenerative and memory disorders.
Short-term climate change and the extinction of the snail
Rhachistia aldabrae
(Gastropoda: Pulmonata)
Authors: Gerlach Justin
Published: August 2007

The only known population of the Aldabra banded snail
Rhachistia aldabrae
declined through the late twentieth century, leading to its extinction in the late 1990s. This occurred within a stable habitat and its extinction is attributable to decreasing rainfall on Aldabra atoll, associated with regional changes in rainfall patterns in the late twentieth and early twenty-first century. It is proposed that the extinction of this species is a direct result of decreasing rainfall leading to increased mortality of juvenile snails.
Chitosan-mediated crystallization and assembly of hydroxyapatite nanoparticles into hybrid nanostructured films
Authors: Kumar R , Prakash K.H , Cheang P , Gower L , Khor K.A
Published: August 2007

The synthesis and subsequent assembly of nearly spherical nano-hydroxyapatite (nHA) particles in the presence of trace amounts of the polysaccharide chitosan was carried out employing a wet chemical approach. Chitosan addition during synthesis not only modulated HA crystallization but also aided in the assembly of nHA particles onto itself. Solvent extraction from these suspensions formed iridescent films, of which the bottom few layers were rich in self-assembled nHA particle arrays. The cross-section of these hybrid films revealed compositional and hence structural grading of the two phases and exhibited a unique morphology in which assembled nHA particles gradually gave way to chitosan-rich top layers. Transmission electron microscope and selected area electron diffraction studies suggested that the basal plane of HA had interacted with chitosan, and scanning electron microscope studies of the hybrid films revealed multi-length scale hierarchical architecture composed of HA and chitosan. Phase identification was carried out by X-ray diffraction (XRD) and Rietveld analysis of digitized XRD data showed that the basic apatite structure was preserved, but chitosan inclusion induced subtle changes to the HA unit cell. The refinement of crystallite shape using the Popa method clearly indicated a distinct change in the growth direction of HA crystallites from [001] to [100] with increasing chitosan concentration. The paper also discusses the likelihood of chitosan phosphorylation during synthesis, which we believe to be a pathway, by which chitosan molecules chemically interact with calcium phosphate precursor compounds and orchestrate the crystallization of nHA particles. Additionally, the paper suggests several interesting biomedical applications for graded nHA–chitosan nanostructured films.
Trivers–Willard at birth and one year: evidence from US natality data 1983–2001
Authors: Almond Douglas , Edlund Lena
Published: August 2007

Trivers & Willard (TW) hypothesized that evolution would favour deviations from the population sex ratio in response to parental condition: parents in good condition would have more sons and parents in poor condition would have more daughters. We analyse the universe of US linked births and infant deaths to white mothers 1983–2001, covering 48 million births and 310 000 deaths. We find that (i) married, better educated and younger mothers bore more sons and (ii) infant deaths were more male if the mother was unmarried and young. Our findings highlight the potential role of offspring sex ratio as an indicator of maternal status, and the role of infant mortality in shaping a TW pattern in the breeding population.
A polar system of intercontinental bird migration
Authors: Alerstam Thomas , Bäckman Johan , Gudmundsson Gudmundur A , Hedenström Anders , Henningsson Sara S , Karlsson Håkan , Rosén Mikael , Strandberg Roine
Published: August 2007

Studies of bird migration in the Beringia region of Alaska and eastern Siberia are of special interest for revealing the importance of bird migration between Eurasia and North America, for evaluating orientation principles used by the birds at polar latitudes and for understanding the evolutionary implications of intercontinental migratory connectivity among birds as well as their parasites. We used tracking radar placed onboard the ice-breaker Oden to register bird migratory flights from 30 July to 19 August 2005 and we encountered extensive bird migration in the whole Beringia range from latitude 64° N in Bering Strait up to latitude 75° N far north of Wrangel Island, with eastward flights making up 79% of all track directions.

The results from Beringia were used in combination with radar studies from the Arctic Ocean north of Siberia and in the Beaufort Sea to make a reconstruction of a major Siberian–American bird migration system in a wide Arctic sector between longitudes 110° E and 130° W, spanning one-third of the entire circumpolar circle. This system was estimated to involve more than 2 million birds, mainly shorebirds, terns and skuas, flying across the Arctic Ocean at mean altitudes exceeding 1 km (maximum altitudes 3–5 km). Great circle orientation provided a significantly better fit with observed flight directions at 20 different sites and areas than constant geographical compass orientation. The long flights over the sea spanned 40–80 degrees of longitude, corresponding to distances and durations of 1400–2600 km and 26–48 hours, respectively. The birds continued from this eastward migration system over the Arctic Ocean into several different flyway systems at the American continents and the Pacific Ocean. Minimization of distances between tundra breeding sectors and northerly stopover sites, in combination with the Beringia glacial refugium and colonization history, seemed to be important for the evolution of this major polar bird migration system.
The adaptive value of parental responsiveness to nestling begging
Authors: Grodzinski Uri , Lotem Arnon
Published: August 2007

Despite extensive theoretical and empirical research into offspring food solicitation behaviour as a model for parent–offspring conflict and communication, the adaptive value of parental responsiveness to begging has never been tested experimentally. Game theory models, as well as empirical studies, suggest that begging conveys information on offspring state, which implies that parental investment can be better translated to fitness by responding to begging when allocating resources rather than by ignoring it. However, this assumption and its underlying mechanisms have received little or no attention. Here we show by experiments with hand-raised house sparrow (Passer domesticus) nestlings that a ‘responsive parent’ will do better than a hypothetical ‘non-responsive’ mutant (that provides similar food amounts, but irrespective of begging). This is neither because food-deprived nestlings convert food to mass more efficiently, however, nor because responsiveness reduces costly begging. Rather, responsiveness to begging is adaptive because it reduces two opposing risks: one is wasting time when returning too soon to feed already satiated nestlings and the other is repeatedly overlooking some nestlings as a result of the stochastic nature of a random, non-responsive strategy. This study provides the first experimental evidence for the adaptive value of parental responsiveness to offspring begging.
Phenotypic plasticity mediates climate change responses among invasive and indigenous arthropods
Authors: Chown Steven L , Slabber Sarette , McGeoch Melodie A , Janion Charlene , Leinaas Hans Petter
Published: August 2007

Synergies between global change and biological invasion have been identified as a major potential threat to global biodiversity and human welfare. The global change-type drought characteristic of many temperate terrestrial ecosystems is especially significant because it will apparently favour invasive over indigenous species, adding to the burden of conservation and compromising ecosystem service delivery. However, the nature of and mechanisms underlying this synergy remain poorly explored. Here we show that in a temperate terrestrial ecosystem, invasive and indigenous springtail species differ in the form of their phenotypic plasticity such that warmer conditions promote survival of desiccation in the invasive species and reduce it in the indigenous ones. These differences are consistent with significant declines in the densities of indigenous species and little change in those of invasive species in a manipulative field experiment that mimicked climate change trends. We suggest that it is not so much the extent of phenotypic plasticity that distinguishes climate change responses among these invasive and indigenous species, as the form that this plasticity takes. Nonetheless, this differential physiological response provides support for the idea that in temperate terrestrial systems experiencing global change-type drought, invasive species may well be at an advantage relative to their indigenous counterparts.
Movements of foraging king penguins through marine mesoscale eddies
Authors: Cotté Cédric , Park Young-Hyang , Guinet Christophe , Bost Charles-André
Published: August 2007

Despite increasing evidence that marine predators associate with mesoscale eddies, how these marine features influence foraging movements is still unclear. This study investigates the relationship of at-sea movements of king penguins to mesoscale eddies using oceanographic remote sensing and movement data from 43 individual trips over 4 years. Simultaneous satellite measurements provided information on gradients of sea surface temperature and currents associated with eddies determined from altimetry. Penguins tended to swim rapidly with currents as they travelled towards foraging zones. Swimming speed indicative of foraging occurred within mesoscale fronts and strong currents associated with eddies at the Polar Front. These results demonstrate the importance of mesoscale eddies in directing foraging efforts to allow predators to rapidly get to rich areas where high concentrations of prey are likely to be encountered. When returning to the colony to relieve the incubating partner or to feed the chick, the birds followed a direct and rapid path, seemingly ignoring currents.
A protective function for aggressive mimicry?
Authors: Côté Isabelle M , Cheney Karen L
Published: August 2007

Mimicry often involves a protective element, whereby the risk of predation on mimics is reduced owing to their resemblance to unpalatable models. However, protection from predation has so far seemed unimportant in aggressive mimicry, where mimics are usually predators rather than prey. Here, we demonstrate that bluestriped fangblennies (
Plagiotremus rhinorhynchos
), which are aggressive mimics of juvenile bluestreak cleaner wrasse (
Labroides dimidiatus
), derive significant protection benefits from their resemblance to cleaner fish. Field observations revealed that mimetic fangblennies were chased by potential victims less often than individuals of a closely related, ecologically and behaviourally similar but non-mimetic species (
Plagiotremus tapeinosoma
). After attacks, proximity to models protected mimics from retaliation by victims, but the effect of colour similarity was less clear. Both colour resemblance and physical proximity to models thus appear to protect cleaner-fish mimics from aggression by potential and actual victims of their attacks. Our results suggest that the mimicry types observed in nature, which are usually distinguished on the basis of the benefits accrued to mimics, may in fact overlap greatly in the benefits provided.
Integrating biomass, sulphate and sea-salt aerosol responses into a microphysical chemical parcel model: implications for climate studies
Authors: Ghosh S , Smith M.H , Rap A
Published: August 2007

Aerosols are known to influence significantly the radiative budget of the Earth. Although the direct effect (whereby aerosols scatter and absorb solar and thermal infrared radiation) has a large perturbing influence on the radiation budget, the indirect effect (whereby aerosols modify the microphysical and hence the radiative properties and amounts of clouds) poses a greater challenge to climate modellers. This is because aerosols undergo chemical and physical changes while in the atmosphere, notably within clouds, and are removed largely by precipitation. The way in which aerosols are processed by clouds depends on the type, abundance and the mixing state of the aerosols concerned. A parametrization with sulphate and sea-salt aerosol has been successfully integrated within the Hadley Centre general circulation model (GCM). The results of this combined parametrization indicate a significantly reduced role, compared with previous estimates, for sulphate aerosol in cloud droplet nucleation and, consequently, in indirect radiative forcing. However, in this bicomponent system, the cloud droplet number concentration,Nd(a crucial parameter that is used in GCMs for radiative transfer calculations), is a smoothly varying function of the sulphate aerosol loading. Apart from sea-salt and sulphate aerosol particles, biomass aerosol particles are also present widely in the troposphere. We find that biomass smoke can significantly perturb the activation and growth of both sulphate and sea-salt particles. For a fixed salt loading,Ndincreases linearly with modest increases in sulphate and smoke masses, but significant nonlinearities are observed at higher non-sea-salt mass loadings. This non-intuitiveNdvariation poses a fresh challenge to climate modellers.
Optimal annual routines: behaviour in the context of physiology and ecology
Authors: McNamara John M , Houston Alasdair I
Published: August 2007

Organisms in a seasonal environment often schedule activities in a regular way over the year. If we assume that such annual routines have been shaped by natural selection then life-history theory should provide a basis for explaining them. We argue that many life-history trade-offs are mediated by underlying physiological variables that act on various time scales. The dynamics of these variables often preclude considering one period of the year in isolation. In order to capture the essence of annual routines, and many life-history traits, a detailed model of changes in physiological state over the annual cycle is required. We outline a modelling approach based on suitable physiological and ecological state variables that can capture this underlying biology, and describe how models based on this approach can be used to generate a range of insights and predictions.
Agricultural sustainability: concepts, principles and evidence
Authors: Pretty Jules
Published: August 2007

Concerns about sustainability in agricultural systems centre on the need to develop technologies and practices that do not have adverse effects on environmental goods and services, are accessible to and effective for farmers, and lead to improvements in food productivity. Despite great progress in agricultural productivity in the past half-century, with crop and livestock productivity strongly driven by increased use of fertilizers, irrigation water, agricultural machinery, pesticides and land, it would be over-optimistic to assume that these relationships will remain linear in the future. New approaches are needed that will integrate biological and ecological processes into food production, minimize the use of those non-renewable inputs that cause harm to the environment or to the health of farmers and consumers, make productive use of the knowledge and skills of farmers, so substituting human capital for costly external inputs, and make productive use of people's collective capacities to work together to solve common agricultural and natural resource problems, such as for pest, watershed, irrigation, forest and credit management. These principles help to build important capital assets for agricultural systems: natural; social; human; physical; and financial capital. Improving natural capital is a central aim, and dividends can come from making the best use of the genotypes of crops and animals and the ecological conditions under which they are grown or raised. Agricultural sustainability suggests a focus on both genotype improvements through the full range of modern biological approaches and improved understanding of the benefits of ecological and agronomic management, manipulation and redesign. The ecological management of agroecosystems that addresses energy flows, nutrient cycling, population-regulating mechanisms and system resilience can lead to the redesign of agriculture at a landscape scale. Sustainable agriculture outcomes can be positive for food productivity, reduced pesticide use and carbon balances. Significant challenges, however, remain to develop national and international policies to support the wider emergence of more sustainable forms of agricultural production across both industrialized and developing countries.
Methodological improvements in the expression of foreign genes and in gene replacement in the phytopathogenic fungus Botrytis cinerea
Authors: NODA JUDITH , BRITO NÉLIDA , ESPINO JOSÉ J. , GONZÁLEZ CELEDONIO
Published: August 2007

Genetic transformation is generally carried out in Botrytis cinerea by random integration of the foreign DNA into the genome, resulting in transformants that show differences among them in, for example, the expression of a reporter gene. Here we report a system for site‐directed integration in which a novel recipient strain containing a 5′‐truncated copy of the hygromycin resistance gene, hph, is transformed with a vector containing another truncated copy, now in the opposite end, of the same selection marker. Homologous recombination in the region shared by these two truncated copies of hph is the only way by which antibiotic‐resistant transformants can be generated. The transformation frequency obtained for the site‐directed strategy was only three‐fold lower than that of the standard transformation, and all the transformants had at least one copy of the plasmid integrated at the expected locus. This system was tested by the expression of the green fluorescent protein and we found that the levels of this protein were more homogeneous among the transformants, when compared with those obtained by random integration. On the other hand, in this paper, we also tried to optimize gene replacements in B. cinerea, which are generally carried out by transformation with an antibiotic resistance marker flanked by regions homologous to the target gene. We studied the influence of the length of these regions on the frequency of replacement of the B. cinerea gene cel5A. Lengths between 500 and 2000 bp gave similar frequencies (about 60%), while lengths of 100 bp decreased the frequency to 6%, showing that 500 bp is a convenient size that would give optimal gene replacement frequencies in this fungus.