bluuebunny/crossref_metadata_2025 huggingface dataset:
Impact of chemical elicitor applications on greenhouse tomato plants and population growth of the green peach aphid, Myzus persicae
Authors: Boughton Anthony J. , Hoover Kelli , Felton Gary W.
Published: August 2006

Recent advances in the understanding of plant signaling pathways have opened the way for using elicitor‐induced plant resistance as a tactic for protecting plants against arthropod pests. Four common elicitors of induced responses in tomato, Lycopersicon esculentum Mill. (Solanaceae), were evaluated with regard to phytotoxicity, induction of plant defensive proteins, and effects on population growth and fecundity of a common pest, the green peach aphid, Myzus persicae (Sulzer) (Homoptera: Aphididae). Ethephon and methyl jasmonate (MJ) treatments caused varying degrees of phytotoxicity. Ethephon caused pronounced changes in plant growth form and severe, dose‐dependent negative impacts on plant growth and flowering. Effects with MJ were milder, but still caused temporary inhibition of development, leading to smaller plants and delayed flowering. The commercial elicitors benzothiadiazole (BTH) and harpin did not cause detectable phytotoxicity. The highest doses of ethephon and MJ significantly increased leaf peroxidase (POD) levels but only MJ treatments significantly increased polyphenol oxidase (PPO) levels. BTH and harpin had no detectable effects on POD and PPO. Populations of green peach aphids grew significantly more slowly on plants treated with BTH or MJ than on control plants or plants treated with harpin or ethephon. Slowed aphid population growth on BTH‐treated plants was due to significant reductions in aphid fecundity, although this was independent of changes in time to onset of reproduction or time to death. Aphid fecundity was also reduced on MJ‐treated plants relative to controls, but this difference was not statistically significant, suggesting that other mechanisms are involved in slowing aphid population growth on MJ‐treated plants. Growth of aphid populations on plants treated with a MJ–BTH mixture was reduced almost as much as with treatments of MJ alone, suggesting that antagonism between JA‐dependant and SA‐dependent plant signaling pathways is only mild with regard to induced defenses against aphids.
Potential distribution and relative abundance of swede midge, Contarinia nasturtii, an invasive pest in Canada
Authors: Olfert O. , Hallett R. , Weiss R.M. , Soroka J. , Goodfellow S.
Published: August 2006

The swede midge, Contarinia nasturtii (Kieffer) (Diptera: Cecidomyiidae), is a pest of most cultivated Brassicaceae such as broccoli, canola, cauliflower, cabbage, and Brussels sprouts. The species primarily has a Palaearctic distribution and occurs throughout Europe and southwestern Asia to the Caucasus. Between 1996 and 1999, producers of cruciferous vegetables in Ontario, Canada, reported crop damage that was consistent with damage symptoms characteristic of C. nasturtii feeding and in 2000, field studies confirmed that this damage was caused by C. nasturtii. A bioclimatic model was developed to predict potential range and relative abundance of C. nasturtii in Canada in order to determine the impact of the establishment and spread of C. nasturtii populations. Model output indicated that C. nasturtii could potentially become established in all provinces of Canada, with the risk being greatest in southwestern British Columbia, southern Ontario and Quebec, New Brunswick, Nova Scotia, and Prince Edward Island. Results indicated that C. nasturtii population growth in the Prairie Ecozone of western Canada would be greatest in years with above average precipitation.
Spatio‐temporal abundance of flushing leaves shapes host selection in the willow leaf beetle, Plagiodera versicolora
Authors: Egusa Sawako , Nishida Takayoshi , Fujisaki Kenji , Sawada Hiroichi
Published: August 2006

In the willow leaf beetle, Plagiodera versicolora (Laicharting) (Coleoptera: Chrysomelidae), food resources available for adults are severely restricted by leaf toughness, which increases with age. Nevertheless, females require their own food almost all their life in order to produce eggs. In this paper, we have focused our attention on the spatio‐temporal abundance of flushing leaves and have examined its effect on host‐plant selection by adults among four co‐occurring willow species (Salix chaenomeloides, Salix eriocarpa, Salix integra, and Salix serissaefolia) (Salicaceae) by field observations and experiments at two spatial scales. Among the various factors associated with this, the amount of new leaf production contributed maximally to variation in adult abundance. By conducting two experiments, we confirmed that the adults preferentially flew towards willow trees with abundant flushing leaves. Furthermore, we detected substantial seasonal changes in new leaf abundance and realized fecundity in the field, and a strong positive correlation was observed between them. Availability of adult food resources limited the reproductive performance of adults, particularly in mid‐summer when only S. serissaefolia produced a few new leaves. These results supported the substantial effect of new leaf abundance on adult abundance in the field. Thus, we concluded that adult feeding is a critical factor that shapes the host‐plant selection of P. versicolora and determines its seasonal occurrence through the dispersal and settlement of adults.
Factors affecting DNA preservation from museum‐collected lepidopteran specimens
Authors: Mandrioli Mauro , Borsatti Federica , Mola Lucrezia
Published: August 2006

Recent innovations in molecular genetics made DNA an intriguing molecule not only in molecular biology, but also in ecology and evolutionary and conservation biology. Despite this general interest, several discrepancies have been reported in the literature regarding the techniques for preserving insects for DNA analysis, prompting us to analyse the effects of different storage conditions on lepidopteran DNA preservation. In particular, in the present paper, adults of the cabbage moth, Mamestra brassicae (L.) (Lepidoptera: Noctuidae), were stored under various conditions in order to verify which method is the most suitable to preserve lepidopteran specimens for DNA studies. Mamestra brassicae adults were stored by rapid desiccation with silica gel, by preservation in acetone, 2‐propanol, Carnoy's or ethanol (both at 75 and 100% concentrations) solutions, and finally by storage in an ultracold freezer and liquid nitrogen. Adults preserved by each method were used to extract DNA at the aim of verifying the size of the extracted DNAs, the extraction yield and the possibility of using these samples to amplify both short and long DNA sequences by polymerase chain reaction. The results were compared with those obtained using fresh samples acting as controls. Acetone preservation appeared to be the most recommendable method for moth specimens as it proved to be a good storage medium for DNA analysis, it is cost‐effective, and it is applicable not only to field surveys, but also to obtain efficient and low‐cost storage of lepidopteran specimens in museum collections.
Delayed mating reduces fecundity of blackheaded fireworm, Rhopobota naevana, on cranberry
Authors: Fitzpatrick Sheila M.
Published: August 2006

This study examines the effects of delayed mating on two successive generations of blackheaded fireworm, Rhopobota naevana Hübner (Lepidoptera: Tortricidae), a pest of cranberry, Vaccinium macrocarpon Aiton (Ericaceae). The first (spring) generation produces eggs that hatch soon after oviposition, whereas the second (summer) generation produces mostly diapause eggs. Unmated female and male moths were placed together on the first, second, fourth, sixth, or eighth day after emergence. In the first generation, incidence of mating was greatest in the 1‐, 2‐, and 4‐day treatments then declined as female survival decreased. In the second generation, incidence of mating was lowest in the 1‐day treatment and greatest in the 2‐, 4‐, and 6‐day treatments. Most second generation females in the 6‐ and 8‐day treatments survived to mate. The mean oviposition period was 2.6 days for first generation females and 4.1 days for second generation females. Fecundity of singly mated females in both generations declined as age at mating advanced, but the pattern of decline differed between generations. First generation females that were mated on the first or second day laid more eggs than those mated on the fourth, sixth, or eighth day, and the number of infertile eggs increased as age at mating advanced. Fecundity of second generation females declined more gradually and the number of infertile eggs was greatest for females mated on the first, sixth, or eighth day. A consequence of the marked decline in fecundity due to mating delays in the first generation was that mean fecundity of the entire group of first generation females was ca. 13% less than that of the group of second generation females. On cranberry farms, pheromone‐mediated mating disruption can prevent or delay mating of blackheaded fireworm. If the frequency of disrupted (prevented and delayed) matings is similar in the two generations, fewer eggs will be laid in the first generation than in the second.
Insecticide resistance in Chinese populations of the Culex pipiens complex through esterase overproduction
Authors: Cui F. , Lin L.‐F. , Qiao C.‐L. , Xu Y. , Marquine M. , Weill M. , Raymond M.
Published: August 2006

In most parts of China, mosquitoes have been subjected to organophosphate (OP) insecticide treatments since the mid‐1960s, and resistance gene monitoring in the Culex pipiens complex (Diptera: Culicidae) started in only a few locations from the end of the 1980s. Many resistant alleles at the Ester locus have been found in field populations, including those commonly found around the world (EsterB1 and Ester2), and those endemic to China (EsterB6, EsterB7, Ester8, and Ester9). This situation is atypical, and may represent a complex situation for the evolution of insecticide resistance genes in China. To increase our understanding of the Chinese situation and our ability to manage resistance in the C. pipiens complex, a large study was performed. Twenty field populations were sampled from Beijing to Guangzhou. Bioassays with five insecticides (dichlorvos, parathion, chlorpyrifos, 2‐sec‐butylphenyl methyl carbamate, and propoxur) disclosed resistance levels variable according to the geographic origin, and up to 85‐fold for dichlorvos. Six overproduced esterases were identified, including two that have not been previously described. Most of them were found in all samples, although at variable frequencies, suggesting variable selection or a transient situation, e.g., each one was recently restricted to a particular geographic area. The results are discussed in the context of recent alterations to insecticide campaigns, and of the evolution of resistance genes in Chinese C. pipiens populations.
Tooth size and skin thickness in mature sockeye salmon: evidence for habitat constraints and variable investment between the sexes
Authors: Johnson S. P. , Carlson S. M. , Quinn T. P.
Published: August 2006

Abstract –  Pacific salmon develop many sexually dimorphic features at maturity, and the extent of development varies among populations. In this study, we compared a suite of traits including body length, body depth, jaw length, tooth size and skin mass in male and female sockeye salmon breeding in beach and creek habitats. Both tooth size and skin mass varied positively with body length. Within each of the breeding habitats, males had longer teeth than females, and within each sex, beach spawners had longer teeth than creek spawners. Males also had heavier skin than females in each habitat but, unlike the case with tooth size, creek spawners showed a much stronger relationship between skin mass and body length than did beach spawners. Tooth length was positively related to jaw length and skin mass among individuals within a given sex and habitat. Taken together, these results suggested that variation in tooth size parallels variation in other sexually dimorphic traits. Males and beach spawners tend to exhibit large trait values relative to females and creek spawners, and ‘well‐endowed’ individuals displayed high values of all traits rather than a trade‐off as might occur if investment in one trait compromised investment in others. However, the finding that creek fish tended to have thicker skin for a given body length than did beach fish suggested that factors other than merely defense against conspecifics during battle, such as abrasion and desiccation resistance in small streams, may influence the evolution of skin mass in mature sockeye salmon.
Runx2 expression is associated with pathologic new bone formation around radicular cysts: an immunohistochemical demonstration
Authors: Kusafuka Kimihide , Sasaguri Kenichi , Sato Sadao , Takemura Tamiko , Kameya Toru
Published: August 2006

Background:  Radicular cysts are the most common cysts in human jaw bones. These lesions induce bone remodeling of the surrounding alveolar bones, which was termed ‘condensing osteitis’, and was suggested to be related to cells of the osteoblastic lineage. The Runx2 (core‐binding protein [cbfa]1/polyoma enhancer‐binding protein [pebp]2αA) was shown to be a DNA‐binding transcriptional molecule expressed in osteoprogenitor cells.

Methods:  We confirmed the specificity of anti‐Runx2 antiserum, using Western blotting analysis. We investigated the expression and localization of Runx2 in 32 radicular cyst cases with bone tissue fragments, immunohistochemically.

Results:  Signals for Runx2 were seen in 18 cases (56.3%) of radicular cysts with bone formation. These signals were immunolocalized in the nuclei of the spindle‐shaped osteoprogenitor cells in the cyst walls, whereas only a few signals were seen in the cuboidal osteoblastic cells near the fibrous bones. Signals for type I collagen were immunolocalized in the dense collagen fibers in the cyst walls and in the matrix of the fibrous bone around the radicular cysts, whereas no signals were seen on the inner portions with inflammatory cell infiltration of the cyst walls. Very weak signals for transforming growth factor (TGF)‐β1 were infrequently seen in the osteoblasts of the fibrous bone, whereas signals for TGF‐β2 were observed in young osteocytes in the fibrous bones, in B‐cell lymphocytes infiltrating into the inner portions, and on the cellular membranes of the lining epithelium.

Conclusions:  The nuclear expression of Runx2 in spindle‐shaped cells in the outer portions may play an essential role in the induction of fibrous bone tissue around radicular cysts. TGF‐β2 may play a role in the production of type I collagen, which acts as a template for pathologic new bone formation, in radicular cysts.
Characterisation of magnesium nutrition and interaction of magnesium and potassium in rice
Authors: Ding Y. , Luo W. , Xu G.
Published: August 2006

Magnesium (Mg) is known as one of the essential nutrients for higher plants; yet, the preliminary physiological responses of field crops to its deficiency or excess, particularly to its interaction with potassium (K), remain largely unknown. In this study, we observed that Mg deficiency in rice (Oryza sativa) [less than 1.1 mg g−1 dry weight (DW) in the shoot] resulted in significant reduction in shoot biomass, decrease in total chlorophyll concentration and net photosynthetic rate and reduction in activities of both nitrate reductase [NR; enzyme classification (EC) 1.6.6.1] and glutamine synthetase (EC 6.3.1.2) in the leaves. However, the Mg‐deficient plant contained higher starch in the leaves, and partitioned larger biomass into roots. Excess of Mg (more than 3.0 mg g−1 DW in the shoot), together with low K supply, suppressed NR activity and decreased concentration of soluble sugar in the leaves. There were great antagonistic and moderately synergistic effects between K and Mg, but the effects of K were much more significant than those of Mg on their uptake and translocation, NR activity and net photosynthetic rate in the leaves. The optimum weight ratio of K to Mg ranged between 22 and 25 in the leaves at tillering stage. Mg deficiency was not compensated for by moderate supply of K but was aggravated by excess supply of K, suggesting specific roles of Mg in both dry matter production and partition of carbon assimilates in rice.
Characterization of Binding Properties of ICAM‐1 Peptides to LFA‐1: Inhibitors of T‐cell Adhesion
Authors: Anderson Meagan E. , Tejo Bimo A. , Yakovleva Tatyana , Siahaan Teruna J.
Published: August 2006

In the present study, we characterized the binding site of two intercellular adhesion molecule‐1‐derived cyclic peptides, cIBC and cIBR, to the LFA‐1 on the surface of T cells. These peptides had been able to inhibit LFA‐1/intercellular adhesion molecule‐1 signal by blocking the signal‐2 of immune synapse. Both peptides prefer to bind to the closed form of LFA‐1 I‐domain, indicating that two peptides act as allosteric inhibitors against intercellular adhesion molecule‐1. Binding site mapping using monoclonal antibodies proposes that cIBC binds to around residues 266–272 of LFA‐1 I‐domain where this site is adjacent to the metal ion‐dependent adhesion site. On the other hand, cIBR binds to the pocket called L‐site where is distant from metal ion‐dependent adhesion site. Cross‐inhibition mapping between two peptides show that cIBR could inhibit the binding of cIBC but not vice versa, suggesting that cIBR has some properties that allow this peptide bind to more than one site. Structural comparison between cIBC and cIBR reveals that cIBR is more flexible than cIBC, allowing this peptide bind to exposed region, such as cIBC‐binding site as well as cramped pocket like L‐site. Our findings are important for understanding the selectivity of cIBC and cIBR peptides; thus, they can be conjugated with drugs and transported specifically to the target.
Exploration of Potential Prodrugs of RWJ‐445167, an Oxyguanidine‐based Dual Inhibitor of Thrombin and Factor Xa
Authors: Maryanoff Bruce E. , McComsey David F. , Costanzo Michael J. , Yabut Stephen C. , Lu Tianbao , Player Mark R. , Giardino Edward C. , Damiano Bruce P.
Published: August 2006

Compound 2 (RWJ‐445167; 3DP‐10017), a dual inhibitor of thrombin and factor Xa, was advanced into human clinical studies. However, its oral bioavailability in humans proved to be below acceptable limits. To address this issue, we explored a prodrug approach involving numerous guanidine derivatives. Prodrug candidates of classes A (carbamate derivatives), B (imidate derivatives), and C (alkyl and acyl derivatives), compounds 3–6, were synthesized and evaluated for anticoagulant activity at 2h after oral administration to rats. In comparison to the parent drug (2), little worthwhile improvement was observed for the prodrug candidates.
Prediction of Activity, Synthesis and Biological Testing of anti‐HSV Active Peptides
Authors: Jenssen Håvard , Gutteberg Tore J. , Rekdal Øystein , Lejon Tore
Published: August 2006

Herpes simplex virus infections can be treated with a number of drugs, but as for all pathogens, there is a constant need for new therapies. In the search for lead compounds some peptides have proven to possess an antiviral effect, but it is still unclear what mechanisms are responsible for this effect. We wish to report on the use of principal properties of amino acids for developing quantitative structure–activity relationships (QSAR:s) as a tool for modelling peptide activity and predicting the activity of new peptides. In order to test the reliability of the method, new peptides have been designed by using multivariate methodology, synthesized and tested for a number of responses. Two of the new peptides synthesized were active at lower concentrations than experienced before regarding entry and herpes simplex virus activity, but they were not able to completely inhibit viral infection. This may reflect differences in mode of action of peptides depending on the amino acid content.
TRENDS IN AGE STRUCTURE AND PRODUCTIVITY OF PACIFIC WALRUSES HARVESTED IN THE BERING STRAIT REGION OF ALASKA, 1952–2002
Authors: Garlich‐Miller Joel L. , Quakenbush Lori T. , Bromaghin Jeffrey F.
Published: August 2006

Abstract

Pacific walruses (Odobenus rosmarus divergens) are harvested by subsistence hunters in Alaska as they migrate north through the Bering Strait in the spring. Harvest records and biological specimens have been collected from the Bering Strait communities of Little Diomede, Gambell, and Savoonga since the 1950s. Harvest levels in the Bering Strait region peaked in the late 1980s and declined thereafter; however, there was considerable variation in the size and composition of the harvests among communities and over time. The relationships among characteristics of the community harvests and the presence of temporal trends were investigated using generalized linear models. The proportion of females in the catch increased over time in all three communities, while the proportion pregnant among harvested females declined over the range of sample years. The ages of harvested walruses increased over time in all three communities through the 1980s, after which trends in age stabilized or began to decline. The age of first reproduction was significantly older for females sampled in 1975–1985 than for females sampled between 1952 and 1962 or 1992 and 1998. Factors thought to have influenced the size and composition of the catch over the past 50 yr include hunter preferences, harvest management regimes, environmental conditions, and changes in the population itself.
Hypoxia‐sensing properties of the newborn rat ventral medullary surface in vitro
Authors: Voituron N. , Frugière A. , Champagnat J. , Bodineau L.
Published: August 2006

The ventral medullary surface (VMS) is a region known to exert a respiratory stimulant effect during hypercapnia. Several studies have suggested its involvement in the central inhibition of respiratory rhythm caused by hypoxia. We studied brainstem–spinal cord preparations isolated from newborn rats transiently superfused with a very low O2 medium, causing reversible respiratory depression, to characterize the participation of the VMS in hypoxic respiratory adaptation. In the presence of 0.8 mm Ca2+, very low O2 medium induced an increase in c‐fos expression throughout the VMS. The reduction of synaptic transmission and blockade of the respiratory drive by 0.2 mm Ca2+−1.6 mm Mg2+ abolished c‐fos expression in the medial VMS (at the lateral edge of the pyramidal tract) but not in the perifacial retrotrapezoid nucleus/parafacial respiratory group (RTN/pFRG) VMS, suggesting the existence of perifacial RTN/pFRG hypoxia‐sensing neurons. In the presence of Ca2+ (0.8 mm), lesioning experiments suggested a physiological difference in perifacial RTN/pFRG VMS between the lateral VMS (beneath the ventrolateral part of the facial nucleus) and the middle VMS (beneath the ventromedial part of the facial nucleus), at least in newborn rats. The lateral VMS lesion, corresponding principally to the most rostral part of the pFRG, produced hypoxia‐induced stimulation, whereas the middle VMS lesion, corresponding to the main part of the RTN, abolished hypoxic excitation. This may involve relay via the medial VMS, which is thought to be the parapyramidal group.
Potentiation of transient receptor potential V1 functions by the activation of metabotropic 5‐HT receptors in rat primary sensory neurons
Authors: Ohta Toshio , Ikemi Yuki , Murakami Matsuka , Imagawa Toshiaki , Otsuguro Ken‐ichi , Ito Shigeo
Published: August 2006

5‐Hydroxytryptamine (5‐HT) is one of the major chemical mediators released in injured and inflamed tissue and is capable of inducing hyperalgesiain vivo. However, the cellular mechanisms of 5‐HT‐induced hyperalgesia remain unclear. Transient receptor potential V1 (TRPV1) plays a pivotal role in nociceptive receptors. In the present study, we determined whether 5‐HT changes TRPV1 functions in cultured dorsal root ganglion (DRG) neurons isolated from neonatal rats, using Ca2+imaging and whole‐cell patch‐clamp techniques. In more than 70% of DRG neurons, 5‐HT potentiated the increases of [Ca2+]iinduced by capsaicin, protons and noxious heat. Capsaicin‐induced current and depolarizing responses, and proton‐induced currents were also augmented by 5‐HT. RT‐PCR analysis revealed the expression of 5‐HT2Aand 5‐HT7receptors in rat DRG neurons. Agonists for 5‐HT2Aand 5‐HT7receptors mimicked the potentiating effect of 5‐HT, and their antagonists decreased it. In DRG ipsilateral to the complete Freund's adjuvant‐injected inflammation side, expression levels of 5‐HT2Aand 5‐HT7mRNAs increased, and the potentiating effect of 5‐HT was more prominent than in the contralateral control side. These results suggest that the PKC‐ and PKA‐mediated signalling pathways are involved in the potentiating effect of 5‐HT on TRPV1 functions through the activation of 5‐HT2Aand 5‐HT7receptors, respectively. Under inflammatory conditions, the increases of the biosynthesis of these 5‐HT receptors may lead to further potentiation of TRPV1 functions, resulting in the generation of inflammatory hyperalgesiain vivo.
Efferent‐mediated control of basilar membrane motion
Authors: Cooper N. P. , Guinan J. J.
Published: August 2006

Medial olivocochlear efferent (MOCE) neurones innervate the outer hair cells (OHCs) of the mammalian cochlea, and convey signals that are capable of controlling the sensitivity of the peripheral auditory system in a frequency‐specific manner. Recent methodological developments have allowed the effects of the MOCE system to be observed in vivo at the level of the basilar membrane (BM). These observations have confirmed earlier theories that at least some of the MOCE's effects are mediated via the cochlea's mechanics, with the OHCs acting as the mechanical effectors. However, the new observations have also provided some unexpected twists: apparently, the MOCEs can enhance the BM's responses to some sounds while inhibiting its responses to others, and they can alter the BM's response to a single sound using at least two separate mechanisms. Such observations put new constraints on the way in which the cochlea's mechanics, and the OHCs in particular, are thought to operate.
Kinetics of ion channel modulation by cAMP in rat hippocampal neurones
Authors: Lancaster Barrie , Hu Hua , Gibb Barry , Storm Johan F.
Published: August 2006

Ion channel regulation by cyclic AMP and protein kinase A is a major effector mechanism for monoamine transmitters and neuromodulators in the CNS. Surprisingly, there is little information about the speed and kinetic limits of cAMP–PKA‐dependent excitability changes in the brain. To explore these questions, we used flash photolysis of caged‐cAMP (DMNB‐cAMP) to provide high temporal resolution. The resultant free cAMP concentration was calculated from separate experiments in which this technique was used, in excised patches, to activate cAMP‐sensitive cyclic nucleotide‐gated (CNG) channels expressed in Xenopus oocytes. In hippocampal pyramidal neurones we studied the modulation of a potassium current (slow AHP current, IsAHP) known to be targeted by multiple transmitter systems that use cAMP–PKA. Rapid cAMP elevation by flash photolyis of 200 μm DMNB‐cAMP completely inhibited the K+ current. The estimated yield (1.3–3%) suggests that photolysis of 200 μm caged precursor is sufficient for full PKA activation. By contrast, extended gradual photolysis of 200 μm DMNB‐cAMP caused stable but only partial inhibition. The kinetics of rapid cAMP inhibition of the K+ conductance (time constant 1.5–2 s) were mirrored by changes in firing patterns commencing within 500 ms of rapid cAMP elevation. Maximal increases in firing were short‐lasting (< 60 s) and gave way to moderately enhanced levels of spiking. The results demonstrate how the fidelity of phasic monoamine signalling can be preserved by the cAMP–PKA pathway.
Central chemoreceptors and sympathetic vasomotor outflow
Authors: Moreira Thiago S. , Takakura Ana C. , Colombari Eduardo , Guyenet Patrice G.
Published: August 2006

The present study explores how elevations in brainPincrease the sympathetic nerve discharge (SND). SND, phrenic nerve discharge (PND) and putative sympathoexcitatory vasomotor neurons of the rostral ventrolateral medulla (RVLM) were recorded in anaesthetized sino‐aortic denervated and vagotomized rats. Hypercapnia (end‐expiratory CO2from 5% to 10%) increased SND (97 ± 6%) and the activity of RVLM neurons (67 ± 4%). Injection of kynurenic acid (Kyn, ionotropic glutamate receptor antagonist) into RVLM or the retrotrapezoid nucleus (RTN) eliminated or reduced PND, respectively, but did not change the effect of CO2on SND. Bilateral injection of Kyn or muscimol into the rostral ventral respiratory group (rVRG‐pre‐Bötzinger region, also called CVLM) eliminated PND while increasing the stimulatory effect of CO2on SND. Muscimol injection into commissural part of the solitary tract nucleus (commNTS) had no effect on PND or SND activation by CO2. As expected, injection of Kyn into RVLM or muscimol into commNTS virtually blocked the effect of carotid body stimulation on SND in rats with intact carotid sinus nerves. In conclusion, CO2increases SND by activating RVLM sympathoexcitatory neurons. The relevant central chemoreceptors are probably located within or close to RVLM and not in the NTS or in the rVRG‐pre‐Bötzinger/CVLM region. RVLM sympathoexcitatory neurons may be intrinsically pH‐sensitive and/or receive excitatory synaptic inputs from RTN chemoreceptors. Activation of the central respiratory network reduces the overall sympathetic response to CO2, presumably by activating barosensitive CVLM neurons and inhibiting RTN chemoreceptors.
Monocarboxylate transporter 1 (MCT1) plays a direct role in short‐chain fatty acids absorption in caprine rumen
Authors: Kirat Doaa , Masuoka Junji , Hayashi Hideaki , Iwano Hidetomo , Yokota Hiroshi , Taniyama Hiroyuki , Kato Seiyu
Published: August 2006

Despite the importance of short‐chain fatty acids (SCFA) in maintaining the ruminant physiology, the mechanism of SCFA absorption is still not fully studied. The goal of this study was to elucidate the possible involvement of monocarboxylate transporter 1 (MCT1) in the mechanism of SCFA transport in the caprine rumen, and to delineate the precise cellular localization and the level of MCT1 protein along the entire caprine gastrointestinal tract. RT‐PCR revealed the presence of mRNA encoding for MCT1 in all regions of the caprine gastrointestinal tract. Quantitative Western blot analysis showed that the level of MCT1 protein was in the order of rumen ≥ reticulum > omasum > caecum > proximal colon > distal colon > abomasum > small intestine. Immunohistochemistry and immunofluorescence confocal analyses revealed widespread immunoreactive positivities for MCT1 in the caprine stomach and large intestine. Amongst the stratified squamous epithelial cells of the forestomach, MCT1 was predominantly expressed on the cell boundaries of the stratum basale and stratum spinosum. Double‐immunofluorescence confocal laser‐scanning microscopy confirmed the co‐localization of MCT1 with its ancillary protein, CD147 in the caprine gastrointestinal tract. In vivo and in vitro functional studies, under the influence of the MCT1 inhibitors, p‐chloromercuribenzoate (pCMB) and p‐chloromercuribenzoic acid (pCMBA), demonstrated significant inhibitory effect on acetate and propionate transport in the rumen. This study provides evidence, for the first time in ruminants, that MCT1 has a direct role in the transepithelial transport and efflux of the SCFA across the stratum spinosum and stratum basale of the forestomach toward the blood side.
What is the hair cell transduction channel?
Authors: Corey David P.
Published: August 2006

In contrast to nearly all other sensory systems, the mechanically sensitive ion channel carrying the receptor current into hair cells of the inner ear has not been identified in molecular terms. A number of candidates from at least two different ion channel families have been considered: these include the epithelial sodium channel (ENaC) and acid‐sensing ion channel (ASIC) members of the DEG/ENaC superfamily of amiloride‐sensitive sodium channels, as well as the TRP channels TRPN1, TRPV4, TRPML3 and TRPA1. For each, initial supportive results were followed by further studies that cast doubts on their involvement. No promising candidates have recently emerged, but the TRP family continues to be attractive in general.
Deafness in LIMP2‐deficient mice due to early loss of the potassium channel KCNQ1/KCNE1 in marginal cells of the stria vascularis
Authors: Knipper Marlies , Claussen Cathrin , Rüttiger Lukas , Zimmermann Ulrike , Lüllmann‐Rauch Renate , Eskelinen Eeva‐Liisa , Schröder Jenny , Schwake Michael , Saftig Paul
Published: August 2006

Our previous studies revealed a critical role of the lysosomal membrane protein LIMP2 in the regulation of membrane transport processes in the endocytic pathway. Here we show that LIMP2‐deficient mice display a progressive high‐frequency hearing loss and decreased otoacoustic emissions as early as 4 weeks of age. In temporal overlap to hearing impairment, fluorescence immunohistochemical studies revealed that the potassium channel KCNQ1 and its β‐subunit KCNE1 were almost completely lost in the luminal part of marginal cells in the stria vascularis, affecting first higher and later also lower frequency processing cochlear turns. Concomitant with this, the expression of megalin, a multiligand endocytic receptor, was reduced in luminal surfaces of marginal cells within the stria vascularis. KCNQ1/KCNE1 and megalin were also lost in the dark cells of the vestibular system. Although LIMP2 is normally expressed in all cells of the stria vascularis, in the organ of Corti and cochlear neurons, the lack of LIMP2 preferentially caused a loss of KCNQ1/KCNE1 and megalin, and structural changes were only seen months later, indicating that these proteins are highly sensitive to disturbances in the lysosomal pathway. The spatio‐temporal correlation of the loss of KCNQ1/KCNE1 surface expression and loss of hearing thresholds supports the notion that the decline of functional KCNQ1/KCNE1 is likely to be the primary cause of the hearing loss. Our findings suggest an important role for LIMP2 in the control of the localization and the level of apically expressed membrane proteins such as KCNQ1, KCNE1 and megalin in the stria vascularis.
pH dependence and inhibition by extracellular calcium of proton currents via plasmalemmal vacuolar‐type H+‐ATPase in murine osteoclasts
Authors: Sakai Hiromu , Kawawaki Junko , Moriura Yoshie , Mori Hiroyuki , Morihata Hirokazu , Kuno Miyuki
Published: August 2006

The vacuolar‐type H+‐ATPase (V‐ATPase) in the plasma membrane of a variety of cells serves as an acid‐secreting pathway, and its activity is closely related to cellular functions. Massive proton secretion often leads to electrolyte disturbances in the vicinity of the cell and may in turn affect the activity of the V‐ATPase. We characterized, for the first time, the proton currents mediated by plasmalemmal V‐ATPase in murine osteoclast‐like cells and investigated its activity over a wide range of pH gradients across the membrane (ΔpH = extracellular pH – intracellular pH). The V‐ATPase currents were identified as outward H+ currents and were dependent on ATP and sensitive to the inhibitors bafilomycin A1 and N,N′‐dicyclohexylcarbodiimide. Although H+ was transported uphill, the electrochemical gradient for H+ affected the current. The currents were increased by elevating ΔpH and depolarization, and were reduced by lowering ΔpH and hyperpolarization. Elevation of extracellular Ca2+ (5–40 mm) diminished the currents in a dose‐dependent manner and made the voltage dependence more marked. Extracellular Mg2+ mimicked the inhibition. With 40 mm Ca2+, the currents decreased to < 40% at 0 mV and to < 10% at about −80 mV. Increases in the intracellular Ca2+ (0.5–5 μm) did not affect the current. The data suggest that acid secretion through the plasmalemmal V‐ATPase is regulated by a combination of the pH gradient, the membrane potential and the extracellular divalent cations. In osteoclasts, the activity‐dependent accumulation of acids and Ca2+ in the closed extracellular compartment might serve as negative feedback signals for regulating the V‐ATPase.
Amplification of Waves by a Concrete Gravity Substructure: Linear Diffraction Analysis and Estimating the Extreme Crest Height
Authors: van Iperen E. J. , Forristall G. Z. , Battjes J. A. , Pinkster J. A.
Published: August 2006

Diffraction of both regular and irregular waves by a concrete gravity substructure (CGS) was investigated using experimental surface elevation data and computational results of the linear diffraction code DELFRAC. The influence of the box-shaped base that supports the four vertical columns was studied independently from the columns, using data from regular wave model tests of the Malampaya CGS. DELFRAC was shown to give accurate results for the focusing of waves over the submerged structure. Results from regular wave data analysis of model tests of the complete Sakhalin II project Lunskoye CGS were compared to the predictions by the linear diffraction code. For the wave cases tested, the first-order amplitudes were accurately predicted. Diffraction of irregular waves at the Lunskoye CGS was studied in a similar way and linear diffraction theory for random seas gave an excellent prediction of incident wave spectral diffraction, including the peaks in the diffracted spectrum near twice the peak frequency in the input spectrum. The results obtained for the Lunksoye CGS in the present study were consistent with results found in similar studies on less complex structures. An attempt to predict the extreme crest heights from the diffracted spectrum was made using a Weibull distribution, and a second-order expansion of the sea surface that captures the effects of wave steepness, water depth, and directional spreading with no other approximation than the truncation of the expansion at second order. Depth induced breaking appeared to be an important phenomenon limiting the crest heights. The crest heights in a 100-year sea state at the Lunskoye CGS were accurately predicted.
Opposing Activities Protect Against Age-Onset Proteotoxicity
Authors: Cohen Ehud , Bieschke Jan , Perciavalle Rhonda M. , Kelly Jeffery W. , Dillin Andrew
Published: August 2006

Aberrant protein aggregation is a common feature of late-onset neurodegenerative diseases, including Alzheimer's disease, which is associated with the misassembly of the Aβ
1-42
peptide. Aggregation-mediated Aβ
1-42
toxicity was reduced in
Caenorhabiditis elegans
when aging was slowed by decreased insulin/insulin growth factor–1–like signaling (IIS). The downstream transcription factors, heat shock factor 1, and DAF-16 regulate opposing disaggregation and aggregation activities to promote cellular survival in response to constitutive toxic protein aggregation. Because the IIS pathway is central to the regulation of longevity and youthfulness in worms, flies, and mammals, these results suggest a mechanistic link between the aging process and aggregation-mediated proteotoxicity.
Imaging Intracellular Fluorescent Proteins at Nanometer Resolution
Authors: Betzig Eric , Patterson George H. , Sougrat Rachid , Lindwasser O. Wolf , Olenych Scott , Bonifacino Juan S. , Davidson Michael W. , Lippincott-Schwartz Jennifer , Hess Harald F.
Published: August 2006

We introduce a method for optically imaging intracellular proteins at nanometer spatial resolution. Numerous sparse subsets of photoactivatable fluorescent protein molecules were activated, localized (to ∼2 to 25 nanometers), and then bleached. The aggregate position information from all subsets was then assembled into a superresolution image. We used this method—termed photoactivated localization microscopy—to image specific target proteins in thin sections of lysosomes and mitochondria; in fixed whole cells, we imaged vinculin at focal adhesions, actin within a lamellipodium, and the distribution of the retroviral protein Gag at the plasma membrane.
Satellite Gravity Measurements Confirm Accelerated Melting of Greenland Ice Sheet
Authors: Chen J. L. , Wilson C. R. , Tapley B. D.
Published: August 2006

Using time-variable gravity measurements from the Gravity Recovery and Climate Experiment (GRACE) satellite mission, we estimate ice mass changes over Greenland during the period April 2002 to November 2005. After correcting for the effects of spatial filtering and limited resolution of GRACE data, the estimated total ice melting rate over Greenland is –239 ± 23 cubic kilometers per year, mostly from East Greenland. This estimate agrees remarkably well with a recent assessment of –224 ± 41 cubic kilometers per year, based on satellite radar interferometry data. GRACE estimates in southeast Greenland suggest accelerated melting since the summer of 2004, consistent with the latest remote sensing measurements.
Hoxa2
- and Rhombomere-Dependent Development of the Mouse Facial Somatosensory Map
Authors: Oury Franck , Murakami Yasunori , Renaud Jean-Sebastien , Pasqualetti Massimo , Charnay Patrick , Ren Shu-Yue , Rijli Filippo M.
Published: August 2006

In the mouse trigeminal pathway, sensory inputs from distinct facial structures, such as whiskers or lower jaw and lip, are topographically mapped onto the somatosensory cortex through relay stations in the thalamus and hindbrain. In the developing hindbrain, the mechanisms generating such maps remain elusive. We found that in the principal sensory nucleus, the whisker-related map is contributed by rhombomere 3–derived neurons, whereas the rhombomere 2–derived progeny supply the lower jaw and lip representation. Moreover, early
Hoxa2
expression in neuroepithelium prevents the trigeminal nerve from ectopically projecting to the cerebellum, whereas late expression in the principal sensory nucleus promotes selective arborization of whisker-related afferents and topographic connectivity to the thalamus.
Hoxa2
inactivation further results in the absence of whisker-related maps in the postnatal brain. Thus,
Hoxa2
- and rhombomere 3–dependent cues determine the whisker area map and are required for the assembly of the whisker-to-barrel somatosensory circuit.
Altered p-STAT3 (tyr705) expression is associated with histological grading and intratumour microvessel density in hepatocellular carcinoma
Authors: Yang Sheau-Fang , Wang Shen-Nien , Wu Chih-Fung , Yeh Yao-Tsung , Chai Chee-Yin , Chunag Shih-Chang , Sheen Maw-Chang , Lee King-Teh
Published: August 2006

Background:Constitutive activation of signal transducer and activator of transcription 3 at tyrosine residue 705 (p-STAT3 (tyr705)) has been associated with many types of human cancers. However, its potential roles and biological effects in hepatocellular carcinoma (HCC) are not well established.

Aim:To explore whether an altered p-STAT3 (tyr705) expression is associated with angiogenesis or proliferation and thereby plays a part in HCC development.

Methods:Paraffin-wax-embedded sections from 69 patients with HCC were collected in this study. Using a semiquantitative immunohistochemical staining method, the expression patterns of p-STAT3 (tyr705) in both HCC lesions and the adjacent non-tumorous liver parenchyma were analysed. The results obtained were further correlated with intratumour microvessel density (MVD), Ki-67 expression, clinicopathological parameters and overall survival.

Results:A strong p-STAT3 (tyr705) nuclear staining was observed in 49.3% of HCC lesions, but was reported only in 5.8% of the adjacent non-tumorous liver parenchyma (p<0.001). The expression of p-STAT3 (tyr705) in HCC lesions was significantly and positively correlated with the intratumour MVD (p = 0.002), but not with Ki-67 expression. No significant correlation of p-STAT3 (tyr705) was found in addition to histological grading (p = 0.019). Multivariate Cox regression analysis showed that p-STAT3 (tyr705) expression was a significant predictor of overall survival for HCC (p = 0.036), although the Kaplan–Meier survival curves showed no significant difference between the high and low p-STAT3 (tyr705) expression subgroups.

Conclusions:The results showed that p-STAT3 (tyr705) expression was closely correlated with histological grading and intratumour MVD in HCC. Thus, the potential role of p-STAT3 (tyr705) in HCC development may be through these correlations.
Phenotypic heterogeneity in hereditary non-polyposis colorectal cancer: identical germline mutations associated with variable tumour morphology and immunohistochemical expression
Authors: Halvarsson Britta , Müller Wolfram , Planck Maria , Benoni Anna Clara , Mangell Peter , Ottosson Johan , Hallén Magnus , Isinger Anna , Nilbert Mef
Published: August 2006

Background:Hereditary non-polyposis colorectal cancer (HNPCC) is associated with high risks for colorectal and endometrial cancer, young age at onset and an increased risk of multiple primary tumours. Colorectal cancer in HNPCC is characterised by poor tumour differentiation, an expanding growth pattern, and a pronounced lymphocytic reaction with tumour-infiltrating lymphocytes.

Aims and Methods:The mutation spectrum in HNPCC is diverse and in order to clarify whether the HNPCC tumour phenotype is influenced by the underlying genetic alteration, 29 colorectal cancers and 12 adenomas from 24 individuals in two HNPCC families were morphologically and immunohistochemically characterised.

Results:The tumour morphology as well as the immunohistochemical expression of β-catenin varied extensively within the families as well as between synchronous/metachronous colorectal cancers from the same individual. Poor tumour differentiation, an expanding growth pattern, and tumour-infiltrating lymphocytes occurred at higher frequencies in proximal tumours, whereas distal colorectal cancers often lacked distinct HNPCC-associated morphological features.

Conclusions:The clinical, morphological and immunohistochemical variability observed within these families indicates that other mechanisms than the underlying germline mutation influence the HNPCC phenotype. Since morphological features linked to HNPCC are less frequent in distal cancers, it may be particularly relevant to obtain family history and age of onset in these tumours in order to identify individuals with HNPCC.
MODIFICATIONS TO BEKENSTEIN–HAWKING ENTROPY DUE TO ARBITRARY SPIN FIELDS
Authors: MI LI-QIN , LI ZHONG-HENG
Published: August 2006

The modified entropy, due to massless quantum fields of arbitrary spin s≤2, of the Kerr–Taub–NUT black hole is evaluated. The appearance of logarithmic terms is demonstrated. The modified entropy can be reduced to the form proportional to the area of the event horizon. However, modified coefficient not only depend on the characteristics of the black hole but also on the spin of the fields.
MOTION OF A CHARGED PARTICLE IN IONIZED FLUIDS
Authors: BEDIN LUCIANO , THOMPSON MARK
Published: August 2006

We discuss the motion of a charged macromolecule in an ionized fluid in a finite region governed by the interaction of the electrical field described by the Poisson–Boltzmann equation and Stokes' equation. Both the surface of the macromolecule and the external surface of the container are supposed to be sufficiently regular. The case of a fluid occupying an infinite region is also discussed assuming an approximation hypothesis on the electrical field.
EXISTENCE RESULT FOR THE BOUNDARY LAYER OF TRIPLE DECK TYPE WITH KNOWN DISPLACEMENT
Authors: PLANTIÉ LAURENT
Published: August 2006

We give the formulation of the boundary layer problem of triple deck type with a known displacement in von Mises variables. The condition associated with the displacement is transformed into a nonlocal condition. We introduce an appropriate method to prove the existence of a solution. It relies on a semi-discrete problem in which the pressure gradients are considered as a parameter. We prove the existence of a solution of the von Mises problem for Lipschitzian nondecreasing displacements. We can apply the inverse von Mises transform using an original expression of y and we prove that the functions u, v, p satisfy the system in physical variables except v(x, 0) = 0 because of a lack of regularity. We obtain all the asymptotic behaviors when y → +∞.