JOURNAL OF BONE AND MINERAL RESEARCH, Issue S2 2006
Lee S Weinstein
Abstract Fibrous dysplasia (FD) is a focal bone lesion composed of immature mesenchymal osteoblastic precursor cells. Some FD patients also have hyperpigmented skin lesions (café-au-lait spots), gonadotropin-independent sexual precocity, and/or other endocrine and nonendocrine manifestations (McCune-Albright syndrome [MAS]). MAS results from somatic mutations occurring during early development, resulting in a widespread mosaic of normal and mutant-bearing cells, which predicts that the clinical presentation of each patient is determined by the extent and distribution of abnormal cells. These mutations encode constitutively active forms of Gs,, the ubiquitously expressed G protein ,-subunit that couples hormone receptors to intracellular cAMP generation. These mutations lead to substitution of amino acid residues that are critical for the intrinsic GTPase activity that is normally required to deactivate the G protein. This leads to prolonged activation of Gs, and its downstream effectors even with minimal receptor activation. This explains why MAS patients have stimulation of multiple peripheral endocrine glands in the absence of circulating stimulatory pituitary hormones and increased skin pigment, which is normally induced by melanocyte-stimulating hormone through Gs,/cAMP. Similar mutations are also present in 40% of pituitary tumors in acromegaly patients and less commonly in other endocrine tumors. FD results from increased cAMP in bone marrow stromal cells, leading to increased proliferation and abnormal differentiation. Parental origin of the mutated allele may also affect the clinical presentation, because Gs, is imprinted and expressed only from the maternal allele in some tissues (e.g., pituitary somatotrophs). [source]

TERMINATION OF PUPAL DIAPAUSE IN THE BOLLWORM HELICOVERPA ARMIGERA BY PRECOCENE II

INSECT SCIENCE, Issue 4 2001
WANG Fang-hai
Abstract Precocene II terminated pupal diapause in the bollworm Helicoverpa armigera as 20-hydroxyecdysterone did, whereas juvenile hormone analog ZR-515, cyclic adenosine monophosphate (CAMP), and 5-hydroxytryptamine (5-HT) did not. The results indicate that precocene II affects diapausing pupae in the similar way as what was found in the prepupae of the aphid parasitoids, Aphidius matricariae Haliday and Praon volucre Haliday (Hymenoptera: Aphidiidae). It is suggested that precocene II may affect different kinds of termination of diapause in insects. [source]

(+)- and (-)- cis -2-Aminomethylcyclopropanecarboxylic Acids Show Opposite Pharmacology at Recombinant ,1 and ,2 GABAC Receptors

JOURNAL OF NEUROCHEMISTRY, Issue 6 2000
Rujee K. Duke
Abstract: The effects of the enantiomers of (±)-CAMP and(±)-TAMP [(±)- cis - and(±)- trans -2-aminomethylcyclopropanecarboxylic acids,respectively], which are cyclopropane analogues of GABA, were tested onGABAA and GABAC receptors expressed in Xenopuslaevis oocytes using two-electrode voltage clamp methods. (+)-CAMP wasfound to be a potent and full agonist at homooligomeric GABACreceptors (KD,40 ,M andImax,100% at ,1;KD,17 ,M and Imax,100% at ,2) but a very weak antagonist at,1,2,2L GABAAreceptors. In contrast, (-)-CAMP was a very weak antagonist at both,1,2,2L GABAAreceptors and homooligomeric GABAC receptors (IC50,900 ,M at ,1 and ,400 ,M at,2). Furthermore, (+)-CAMP appears to be a superior agonist tothe widely used GABAC receptor partial agonistcis -4-aminocrotonic acid (KD,74,M and Imax,78% at ,1;KD,70 ,M and Imax,82% at ,2). (-)-TAMP was the most potent of thecyclopropane analogues on GABAC receptors (KD,9 ,M and Imax,40% at,1; KD,3 ,M andImax,50-60% at ,2), but it was also amoderately potent GABAA receptor partial agonist(KD,50-60 ,M and Imax,50% at ,1,2,2LGABAA receptors). (+)-TAMP was a less potent partial agonist atGABAC receptors (KD,60 ,M andImax,40% at ,1; KD,30 ,M and Imax,60% at,2) and a weak partial agonist at,1,2,2L GABAAreceptors (KD,500 ,M andImax,50%). None of the isomers of (±)-CAMP and(±)-TAMP displayed any interaction with GABA transport at theconcentrations tested. Molecular modeling based on the present resultsprovided new insights into the chiral preferences for either agonism orantagonism at GABAC receptors. [source]

Regulation of Salmonella typhimurium virulence gene expression by cationic antimicrobial peptides

MOLECULAR MICROBIOLOGY, Issue 1 2003
Martin W. Bader
Summary Cationic antimicrobial peptides (CAMP) represent a conserved and highly effective component of innate immunity. During infection, the Gram-negative pathogen Salmonella typhimurium induces different mechanisms of CAMP resistance that promote pathogenesis in animals. This study shows that exposure of S. typhimurium to sublethal concentrations of CAMP activates the PhoP/PhoQ and RpoS virulence regulons, while repressing the transcription of genes required for flagella synthesis and the invasion-associated type III secretion system. We further demonstrate that growth of S. typhimurium in low doses of the ,-helical peptide C18G induces resistance to CAMP of different structural classes. Inducible resistance depends on the presence of PhoP, indicating that the PhoP/PhoQ system can sense sublethal concentrations of cationic antimicrobial peptides. Growth of S. typhimurium in the presence of CAMP also leads to RpoS-dependent protection against hydrogen peroxide. Because bacterial resistance to oxidative stress and CAMP are induced during infection of animals, CAMP may be an important signal recognized by bacteria on colonization of animal tissues. [source]

The MprF protein is required for lysinylation of phospholipids in listerial membranes and confers resistance to cationic antimicrobial peptides (CAMPs) on Listeria monocytogenes

MOLECULAR MICROBIOLOGY, Issue 5 2006
Kathrin Thedieck
Summary Pathogenic bacteria have to cope with defence mechanisms mediated by adaptive and innate immunity of the host cells. Cationic antimicrobial peptides (CAMPs) represent one of the most effective components of the host innate immune response. Here we establish the function of Lmo1695, a member of the VirR-dependent virulence regulon, recently identified in Listeria monocytogenes. Lmo1695 encodes a membrane protein of 98 kDa with strong homology to the multiple peptide resistance factor (MprF) of Staphylococcus aureus. Like staphylococcal MprF, we found that Lmo1695 is involved in the synthesis of the membrane phospholipid lysylphosphatidylglycerol (L-PG). In addition, Lmo1695 is also essential for lysinylation of diphosphatidylglycerol (DPG), another phospholipid widely distributed in bacterial membranes. A ,lmo1695 mutant lacking the lysinylated phospholipids was particularly susceptible to CAMPs of human and bacterial origin. The mutant strain infected both epithelial cells and macrophages only poorly and was attenuated for virulence when tested in a mouse model of infection. Lmo1695 is a member of a growing list of survival factors which enable growth of L. monocytogenes in different environments. [source]

Growing Up in Guerrilla Camp: The long-Term Impact of Being a Child Soldier in El Salvador's Civil War

ETHOS, Issue 4 2002
Julia Dickson-Gõmez
Many recent wars are characterized by high levels of civilian casualties, a large proportion of whom are women and children. Furthermore, an estimated 300,000 children are actively participating in 36 ongoing or recently ended conflicts around the world. However, there is a dearth of research on the long-term effects of war trauma experienced in childhood or children's active participation in armed conflicts. This article explores the long-term effects of children's active participation in the war in El Salvador by examining four young adults who fought with the guerrilla army as children and adolescents. Comparing these four cases with members of the community who joined and fought with the guerrilla as adults, it will be argued that traumatic experiences were even more devastating when they occurred in early childhood as they destroyed the ability to establish basic trust in competent and nurturing caretakers. Becoming a soldier created additional conflicts as these adolescent soldiers behaved in ways they felt were morally incorrect. Adolescent soldiers were also not given the opportunity to develop autonomy and learn adult peace-time roles. Both the psychological trauma suffered as children as well as continued economic scarcity and violence contribute to these campesinos' difficulties in creating meaningful lives as adults. [source]

Holocaust Survivors in Old Age: The Jerusalem Longitudinal Study

JOURNAL OF AMERICAN GERIATRICS SOCIETY, Issue 3 2008
Jochanan Stesssman MD
OBJECTIVES: To examine the hypothesis that Holocaust exposure during young adulthood negatively affects physical aging, causing greater morbidity, faster deterioration in health parameters, and shorter survival. DESIGN: A longitudinal cohort study of the natural history of an age-homogenous representative sample born in 1920/21 and living in Jerusalem. SETTING: Community-based home assessments. PARTICIPANTS: Four hundred fifty-eight subjects of European origin aged 70 at baseline and 77 at follow-up. MEASUREMENTS: Comprehensive assessment of physical, functional, and psychosocial domains; biographical history of concentration camp internment (Camp), exposure to Nazi occupation during World War II (Exposure), or lack thereof (Controls); and 7-year mortality data from the National Death Registry. RESULTS: Holocaust survivors of the Camp (n=93) and Exposure (n=129) groups were more likely than Controls (n=236) to be male and less educated and have less social support (P=.01), less physical activity (P=.03), greater difficulty in basic activities of daily living (P=.009), poorer self-rated health (P=.04), and greater usage of psychiatric medication (P=.008). No other differences in health parameters or physical illnesses were found. Holocaust survivors had similar rates of deterioration in health and illness parameters over the follow-up period, and 7-year mortality rates were identical. Proportional hazard models showed that being an elderly Holocaust survivor was not predictive of greter 7-year mortality. CONCLUSION: Fifty years after their Holocaust trauma, survivors still displayed significant psychosocial and functional impairment, although no evidence was found to support the hypothesis that the delayed effects of the trauma of the Holocaust negatively influence physical health, health trajectories, or mortality. [source]

Design and power management of a solar-powered "Cool Robot" for polar instrument networks

JOURNAL OF FIELD ROBOTICS (FORMERLY JOURNAL OF ROBOTIC SYSTEMS), Issue 7 2007
Laura E. Ray
The Cool Robot is a four-wheel-drive, solar-powered, autonomous robot designed to support summertime science campaigns in Antarctica and Greenland over distances exceeding 500 km. This paper provides an overview of key features of the robot, including design for good mobility, high efficiency, and long-term deployment under solar power in harsh polar environments. The Cool Robot's solar panel box, comprising panels on four sides and a top panel, encounters insolation variations with a bandwidth of up to 1 Hz due to sastrugi. The paper details a unique photovoltaic control algorithm to accommodate these variations. We deployed the robot at Summit Camp, Greenland to validate its mobility and power budget and to assess the photovoltaic control system. The 61 kg robot drove continuously at 0.78 m/s on soft snow, its 160 W average power demand met by solar power alone under clear skies above 16° sun elevation. The power-control system reliably matched input with demand as insolation varied during testing. A simple GPS waypoint-following algorithm provides low-bandwidth path planning and course correction and demonstrated reliable autonomous navigation during testing over periods of 5,8 h. Field data validate the Cool Robot design models and indicate that it will exceed its design goal of carrying a 15 kg payload 500 km across Antarctica in 2 weeks. A brief description of instrument payloads and scientific studies aided by networks of such autonomous solar robots is provided. © 2007 Wiley Periodicals, Inc. [source]

Front and Back Covers, Volume 22, Number 1.

ANTHROPOLOGY TODAY, Issue 1 2006
February 200
Front and back cover caption, volume 22 issue 1 Front cover 'Strasbourg: 15th night of rioting. A French riot police officer gestures to direct the fire fighters to a torched car after vandalism in the eastern French city of Strasbourg early Wednesday 9 November 2005. Police forces have been deployed in the city as authorities expect a 13th night of disturbances all around France. Schiltigheim, France, 10/11/2005.' This photo illustrates Didier Fassin's editorial on the riots in the French banlieues. Although the immediate cause of the riots must be ascribed, at least in part, to the ill-advised reactions of the French police and government, the Prime Minister proceeded to proclaim a state of emergency, using a 1955 law passed during the war in Algeria. These events call for serious examination not only of what France stands for, especially in terms of racial discrimination, but also of why anthropologists should have felt so uncomfortable about analysing these events, just as they did with the controversy over the veil. The political foundations of the discipline in France posit a knowledge of remote societies rather than of others close to home, and aspire to theoretical universalism combined with an element of colour-blindness which ignores local social realities. Back cover Saving Children. In the back cover photo, a little girl holds a dummy pistol in Bella Camp, near Nazran, Ingushetia, Russia, in November 2002. In this issue Jason Hart considers the ways in which children are commonly represented. Particularly in conditions seen as especially adverse, children's lives have overwhelmingly been viewed through the prism of humanitarianism. Accounts of children living amidst conflict, social upheaval and extreme poverty produced by humanitarian organizations are commonly framed by contrast to Romantic ideals of childhood. The disparity thereby demonstrated has fuelled popular imagination in the developed economies of the world - useful not only in eliciting support for humanitarian action but also, under the current world order, in discrediting certain societies and ultimately in justifying military intervention. Hart argues that anthropology has a valuable role to play in enhancing understanding of the lives of children globally. Key to this is locating children within social, economic and political processes that extend beyond the local to the national and international. Taking the issue of 'child soldiers' as an example, Hart argues for the importance of including a focus upon the ways in which such phenomena as the global arms trade and the foreign and economic policies of Western governments contribute to the circumstances in which children come to engage as combatants. Furthermore, the dangers of such engagement need to be placed in the context of the diverse array of risks encountered by children in impoverished and marginal settings. We urgently need a child-centred ethnography attentive to the interaction between the global and the local in the everyday lives of the young so that we may interrogate more closely the moral authority of those who justify their actions in terms of 'saving children'. [source]

Phenotypic evolution in high-elevation populations of western fence lizards (Sceloporus occidentalis) in the Sierra Nevada Mountains

BIOLOGICAL JOURNAL OF THE LINNEAN SOCIETY, Issue 3 2010
ADAM D. LEACHÉ
Adaptive divergence in response to variable habitats, climates, and altitude is often accentuated along elevation gradients. We investigate phenotypic evolution in body size and coloration in the western fence lizard (Sceloporus occidentalis Baird & Girard, 1852) across elevation gradients in Yosemite National Park, California, situated in the Sierra Nevada mountains of Western North America. High-elevation populations occurring above 2100 m a.s.l. are recognized as a separate subspecies (Sceloporus occidentalis taylori Camp, 1916), with a distinctive phenotype characterized by a large body size and extensive blue ventral pigmentation. We sampled S. occidentalis from across elevation gradients in Yosemite National Park, California, and collected phenotypic data (body size and ventral coloration measurements; 410 specimens) and mitochondrial DNA sequence data (complete NADH1 gene; 969 bp, 181 specimens) to infer phylogenetic relationships, and examine the genetic and phenotypic diversity among populations. Populations of S. occidentalis in Yosemite National Park follow Bergmann's rule and exhibit larger body sizes in colder, high-elevation environments. The high-elevation subspecies S. o. taylori is not monophyletic, and the mitochondrial DNA genealogy supports a model of convergent phenotypic evolution among high-elevation populations belonging to different river drainages. The hypothesis that separate populations of S. occidentalis expanded up river drainages after the recession of glaciers is supported by population demographic analyses, and suggest that Bergmann's clines can evolve rapidly along elevation gradients. The distinctive high-elevation phenotype that is attributable to S. o. taylori has evolved independently several times, and includes adaptive phenotypic changes associated with increases in body size and ventral coloration. © 2010 The Linnean Society of London, Biological Journal of the Linnean Society, 2010, 100, 630,641. [source]

The Aspect Hypothesis: Development of Morphology and Appropriateness of Use

LANGUAGE LEARNING, Issue 2 2006
Llorenç Comajoan
According to the aspect hypothesis (Andersen & Shirai, 1996; Bardovi-Harlig, 2000), perfective morphology emerges before imperfective morphology, it is first used in telic predicates (achievements and accomplishments) and it later extends to atelic predicates (activities and states). The opposite development is hypothesized for imperfective morphology. This study proposes to investigate the emergence of preterite and imperfect morphology in Catalan to examine if the aspectual characteristics of predicates can account for the emergence of morphology and also appropriate use. Past verbal forms in narratives produced by three multilingual learners of Catalan as a foreign language were coded for appropriateness of use, morphology, and lexical aspect. An aspectual analysis of the data provided support for the aspect hypothesis, because achievement and accomplishment predicates in general were inflected for preterite morphology more frequently than were activity and state predicates, and the opposite was found for the emergence of imperfect morphology. The aspectual trends, however, varied for individual learners, tasks, and developmental stages. An analysis of the appropriate use of preterite and imperfect forms showed that morphology was used appropriately in almost all contexts. Prototypical combinations of morphology and aspect tended to be used more appropriately than nonprototypical combinations, as supported by other studies (Cadierno, 2000; Camps, 2002; Giacalone-Ramat, 2002). [source]

The Order of Battle in the Roman Army: Evidence from Marching Camps

OXFORD JOURNAL OF ARCHAEOLOGY, Issue 2 2001
Alan Richardson
The Iron Age in the North-West of Iberia is characterized by settlement patterns in which small hilltop enclosures or castros were dominant. Recent field-survey work has revealed more about the distribution of rural settlement sites in part of this area, and an analysis has been made of the pattern of rural site distributions in relation to the castros. This confirms the continued focal role of castros into the Roman period. An explanation for the settlement pattern in this region and the absence of typically Roman features like developed villas is sought in the nature and extent of Roman military recruitment from the region. [source]

Dopaminergic signalling in the rodent neonatal suprachiasmatic nucleus identifies a role for protein kinase A and mitogen-activated protein kinase in circadian entrainment

EUROPEAN JOURNAL OF NEUROSCIENCE, Issue 2 2002
Irina L. Schurov
Abstract The circadian clock of the suprachiasmatic nuclei (SCN) of perinatal rodents is entrained by maternally derived cues. The SCN of neonatal Syrian hamsters express high-affinity D1 dopamine receptors, and the circadian activity,rest cycle of pups can be entrained by maternal injection of dopaminergic agonists. The present study sought to characterize the intracellular pathways mediating dopaminergic signalling in neonatal rodent SCN. Both dopamine and the D1 agonist SKF81297 caused a dose-dependent increase in phosphorylation of the transcriptional regulator Ca2+/cyclic AMP response element (CRE) binding protein (CREB) in suprachiasmatic GABA-immunoreactive (-IR) neurons held in primary culture. The D1 antagonist SCH23390 blocked this effect. Dopaminergic induction of pCREB-IR in GABA-IR neurons was also blocked by a protein kinase A (PKA) inhibitor, 5,24, and by the MAPK inhibitor, PD98059, whereas KN-62, an inhibitor of Ca2+/calmodulin-dependent (CAM) kinase II/IV was ineffective. Treatment with NMDA increased the level of intracellular Ca2+ in the cultured primary SCN neurons in Mg2+ -free medium, but SKF81297 did not. Blockade of CaM kinase II/IV with KN-62 inhibited glutamatergic induction of pCREB-IR in GABA-IR neurons, whereas 5,24 was ineffective, confirming the independent action of Ca2+ - and cAMP-mediated inputs on pCREB. SKF81297 caused an increase in pERK-IR in SCN cells, and this was blocked by 5,24, indicative of activation of MAPK via D1/cAMP. These results demonstrate that dopaminergic signalling in the neonatal SCN is mediated via the D1-dependent activation of PKA and MAPK, and that this is independent of the glutamatergic regulation via Ca2+ and CaM kinase II/IV responsible for entrainment to the light/dark cycle. [source]

Extracellular cAMP inhibits P2X3 receptors in rat sensory neurones through G protein-mediated mechanism

ACTA PHYSIOLOGICA, Issue 2 2010
M. V. Mamenko
Abstract Aim:, To identify the mechanisms of P2X3 receptor inhibition by extracellular cyclic adenosine monophosphate (cAMP) in rat dorsal root ganglion (DRG) neurones. Methods:, Whole-cell currents were measured in cultured DRG neurones using the combination of voltage and concentration clamp. Results:, We have found that extracellular cAMP inhibits P2X3 -mediated currents in a concentration- and use-dependent manner. The P2X3 currents, activated by ATP applied every 4 min, were inhibited by 55% in the presence of 10 ,m cAMP and by 81% in the presence of 30 ,m cAMP. At 8 min interval between ATP applications the same concentration of cAMP did not alter the currents. Addition of 0.5 mm of guanosine 5,- O -(2-thiodiphosphate) to intracellular solution blocked the inhibitory action of cAMP. The inhibitory effects of cAMP were not mimicked by extracellular application of 30 ,m adenosine. Conclusions:, In this paper, we demonstrate, for the first time, that extracellular application of cAMP to rat sensory neurones inhibits P2X3 receptors via a G protein-coupled mechanism in a use-dependent manner, thus indicating the neuronal expression of specific plasmalemmal cAMP receptor. [source]

Losartan decreases vasopressin-mediated cAMP accumulation in the thick ascending limb of the loop of Henle in rats with congestive heart failure

ACTA PHYSIOLOGICA, Issue 4 2007
M. Torp
Abstract Introduction:, Vasopressin (AVP) stimulates sodium reabsorption and Na,K,2Cl-cotransporter (NKCC2) protein level in the thick ascending limb (TAL) of Henle's loop in rats. Rats with congestive heart failure (CHF) have increased protein level of NKCC2, which can be normalized by angiotensin II receptor type-1 (AT1) blockade with losartan. Aim:, In this study, we investigated whether CHF rats displayed changes in AVP stimulated cAMP formation in the TAL and examined the role of AT1 receptor blockade on this system. Method:, CHF was induced by ligation of the left anterior descending coronary artery (LAD). SHAM-operated rats were used as controls. Half of the rats were treated with losartan (10 mg kg day,1 i.p.). Results:, CHF rats were characterized by increased left ventricular end diastolic pressure. Measurement of cAMP in isolated outer medullary TAL showed that both basal and AVP (10,6 m) stimulated cAMP levels were significantly increased in CHF rats (25.52 ± 4.49 pmol cAMP ,g,1 protein, P < 0.05) compared to Sham rats (8.13 ± 1.14 pmol cAMP ,g,1 protein), P < 0.05). Losartan significantly reduced the basal level of cAMP in CHF rats (CHF: 12.56 ± 1.93 fmol ,g,1 protein vs. Los-CHF: 7.49 ± 1.08, P < 0.05), but not in Sham rats (SHAM: 4.66 ± 0.59 vs. Los-SHAM: 4.75 ± 0.71). AVP-mediated cAMP accumulation was absent in both groups treated with losartan (Los-SHAM: 4.75 ± 0.71 and Los-CHF: 7.49 ± 1.08). Conclusion:, The results indicate that the increased NKCC2 protein level in the mTAL from CHF rats is associated with increased cAMP accumulation in this segment. Furthermore, the finding that AT1 receptor blockade prevents AVP-mediated cAMP accumulation in both SHAM and CHF rats suggests an interaction between angiotensin II and AVP in regulation of mTAL Na reabsorption. [source]

Pituitary and autonomic responses to cold exposures in man

ACTA PHYSIOLOGICA, Issue 4 2005
J. Leppäluoto
Abstract This review presents hormonal responses to various cold exposures and their calorigenic effects in man and some animals. Previous studies in rats have shown that cold exposures activate the hypothalamic-pituitary-thyroid axis. Increased thyroid hormone concentrations lead to heat production via general stimulation of metabolism (obligatory thermogenesis) and possibly via activation of thyroid hormone receptors and uncoupling protein 1 (UCP 1) and deiodinase enzyme genes in the brown adipose tissue (BAT). In human subjects long-term cold exposures do not seem to activate the pituitary-thyroid axis, but rather accelerate the elimination of triiodothyronine (T3), leading to low serum concentrations of free T3 hormone. In corollary to this a hypothyreotic condition with increased serum thyroid-stimulating hormone and impaired mood and cognitive performance can be observed after long-term cold exposures such as wintering. During cold exposures the sympathetic nerve system is activated and noradrenaline is released to blood circulation and to BAT, where it leads to production of cAMP, lipolysis and free fatty acids. Free fatty acids open the mitochondrial proton channel protein in BAT. Protons enter the mitochondria and inhibit ATP synthesis (uncoupling). By this way energy is transformed into heat (facultatory or adaptive thermogenesis). In adult human subjects the amount of BAT is small and adaptive thermogenesis (non-shivering thermogenesis) has a smaller role. UCP 1 with other uncoupling proteins may have other functions in the control of body weight, sugar balance and formation of reactive oxygen species. [source]

Regulation of sperm flagellar motility activation and chemotaxis caused by egg-derived substance(s) in sea cucumber

CYTOSKELETON, Issue 4 2009
Masaya Morita
Abstract The sea cucumber Holothuria atra is a broadcast spawner. Among broadcast spawners, fertilization occurs by means of an egg-derived substance(s) that induces sperm flagellar motility activation and chemotaxis. Holothuria atra sperm were quiescent in seawater, but exhibited flagellar motility activation near eggs with chorion (intact eggs). In addition, they moved in a helical motion toward intact eggs as well as a capillary filled with the water layer of the egg extracts, suggesting that an egg-derived compound(s) causes motility activation and chemotaxis. Furthermore, demembranated sperm flagella were reactivated in high pH (>7.8) solution without cAMP, and a phosphorylation assay using (,-32P)ATP showed that axonemal protein phosphorylation and dephosphorylation also occurred in a pH-dependent manner. These results suggest that the activation of sperm motility in holothurians is controlled by pH-sensitive changes in axonemal protein phosphorylation. Ca2+ concentration affected the swimming trajectory of demembranated sperm, indicating that Ca2+ -binding proteins present at the flagella may be associated with regulation of flagellar waveform. Moreover, the phosphorylation states of several axonemal proteins were Ca2+ -sensitive, indicating that Ca2+ impacts both kinase and phosphatase activities. In addition, in vivo sperm protein phosphorylation occurred after treatment with a water-soluble egg extract. Our results suggest that one or more egg-derived compounds activate motility and subsequent chemotactic behavior via Ca2+ -sensitive flagellar protein phosphorylation. Cell Motil. Cytoskeleton 2009. © 2009 Wiley-Liss, Inc. [source]

Protein kinase A RII-like (R2D2) proteins exhibit differential localization and AKAP interaction,

CYTOSKELETON, Issue 7 2008
Amy E. Hanlon Newell
Abstract A-kinase anchoring proteins (AKAPs) bind to protein kinase A (PKA) via an amphipathic helix domain that interacts with a dimerization/docking domain on the regulatory (R) subunit of PKA. Four other mammalian proteins (ROPN1, ASP, SP17, and CABYR) also contain a highly conserved RII dimerization/docking (R2D2) domain, suggesting all four proteins may interact with all AKAPs in a manner similar to RII. All four of these proteins were originally detected in the flagellum of mammalian sperm. In this report, we demonstrate that all four R2D2 proteins are expressed in a wide variety of tissues and three of the proteins SP17, CABYR, and ASP are located in motile cilia of human bronchus and fallopian tubes. In addition, we detect SP17 in primary cilia. We also provide evidence that ROPN1 and ASP bind to a variety of AKAPs and this interaction can be disrupted with anchoring inhibitor peptides. The interaction of SP17 and CABYR with AKAPs appears to be much more limited. None of the R2D2 proteins appears to bind cAMP, a fundamental characteristic of the regulatory subunits of PKA. These observations suggest that R2D2 proteins utilize docking interactions with AKAPs to accomplish their function of regulating cilia and flagella. Based on location, affinity for AKAPs and lack of affinity for cAMP, it appears that each R2D2 protein has a unique role in this process. Cell Motil. Cytoskeleton 2008. © 2008 Wiley-Liss, Inc. [source]

Simultaneous quantification of cell motility and protein-membrane-association using active contours

CYTOSKELETON, Issue 4 2002
Dirk Dormann
Abstract We present a new method for the quantification of dynamic changes in fluorescence intensities at the cell membrane of moving cells. It is based on an active contour method for cell-edge detection, which allows tracking of changes in cell shape and position. Fluorescence intensities at specific cortical subregions can be followed in space and time and correlated with cell motility. The translocation of two GFP tagged proteins (CRAC and GRP1) from the cytosol to the membrane in response to stimulation with the chemoattractant cAMP during chemotaxis of Dictyostelium cells and studies of the spatio-temporal dynamics of this process exemplify the method: We show that the translocation can be correlated with motility parameters and that quantitative differences in the rate of association and dissociation from the membrane can be observed for the two PH domain containing proteins. The analysis of periodic CRAC translocation to the leading edge of a cell responding to natural cAMP waves in a mound demonstrates the power of this approach. It is not only capable of tracking the outline of cells within aggregates in front of a noisy background, but furthermore allows the construction of spatio-temporal polar plots, capturing the dynamics of the protein distribution at the cell membrane within the cells' moving co-ordinate system. Compilation of data by means of normalised polar plots is suggested as a future tool, which promises the so-far impossible practicability of extensive statistical studies and automated comparison of complex spatio-temporal protein distribution patterns. Cell Motil. Cytoskeleton 52:221,230, 2002. © 2002 Wiley-Liss, Inc. [source]

A novel role of differentiation-inducing factor-1 in Dictyostelium development, assessed by the restoration of a developmental defect in a mutant lacking mitogen-activated protein kinase ERK2

DEVELOPMENT GROWTH & DIFFERENTIATION, Issue 5 2000
Hidekazu Kuwayama
It has been previously reported that the differentiating wild-type cells of Dictyostelium discoideum secrete a diffusible factor or factors that are able to rescue the developmental defect in the mutant lacking extracellular signal-regulated kinase 2 (ERK2), encoded by the gene erkB. In the present study, it is demonstrated that differentiation-inducing factor-1 (DIF-1) for stalk cells can mimic the role of the factor(s) and the mechanism of the action of DIF-1 in the erkB null mutant is also discussed. The mutant usually never forms multicellular aggregates, because of its defect in cyclic adenosine monophosphate (cAMP) signaling. In the presence of 100 n M DIF-1, however, the mutant cells formed tiny slugs, which eventually developed into small fruiting bodies. In contrast, DIF-1 never rescued the developmental arrest of other Dictyostelium mutants lacking adenylyl cyclase A (ACA), cAMP receptors cAR1 and cAR3, heterotrimeric G-protein, the cytosolic regulator of ACA, or the catalytic subunit of cAMP-dependent protein kinase (PKA-C). Most importantly, it was found that DIF-1 did not affect the cellular cAMP level, but rather elevated the transcriptional level of pka during the development of erkB null cells. These results suggest that DIF-1 may rescue the developmental defect in erkB null cells via the increase in PKA activity, thus giving the first conclusive evidence that DIF-1 plays a crucial role in the early events of Dictyostelium development as well as in prestalk and stalk cell induction. [source]

Structural and functional changes in the olfactory pathway of adult Drosophila take place at a critical age

DEVELOPMENTAL NEUROBIOLOGY, Issue 1 2003
Jean-Marc Devaud
Abstract The olfactory system of several holometabolous insect species undergoes anatomical changes after eclosion of the imago, following those occurring during metamorphosis. In parallel, odor experience and learning performance also evolve with age. Here, we analyze the case of adult Drosophila females. Synaptogenesis in the antennal lobe (AL) starts in late pupa and continues during the first days of adult life, at the same time as the behavioral response to odors matures. Individual olfactory glomeruli (DM6, DM2, and V) display specific growth patterns between days 1 and 12 of adult life. Experience can modify the olfactory pathway both structurally and functionally as shown by adaptation experiments. The modifications associated with this form of nonassociative learning seem to take place at a critical age. Exposure to benzaldehyde at days 2,5 of adult life, but not at 8,11, causes behavioral adaptation as well as structural changes in DM2 and V glomeruli. Altered levels in intracellular cAMP, caused by dunce and rutabaga mutants, do not affect the normal changes in glomerular size, at least at day 6 of development, but they prevent those elicited by experience, establishing a molecular difference between glomerular changes of intrinsic versus environmental origin. Taken together, these data demonstrate an imprinting-like phenomenon in the olfactory pathway of young Drosophila adults, and illustrate its glomerulus-specific dynamics. © 2003 Wiley Periodicals, Inc. J Neurobiol 56: 13,23, 2003 [source]

Gap junctional coupling between progenitor cells at the retinal margin of adult goldfish

DEVELOPMENTAL NEUROBIOLOGY, Issue 3 2001
Fuminobu Tamalu
Abstract We prepared living slice preparations of the peripheral retina of adult goldfish to examine electrical membrane properties of progenitor cells at the retinal margin. Cells were voltage-clamped near resting potential and then stepped to either hyperpolarizing or depolarizing test potentials using whole-cell voltage-clamp recordings. Electrophysiologically examined cells were morphologically identified by injecting both Lucifer Yellow (LY) and biocytin. All progenitor cells examined (n = 37) showed a large amount of passively flowing currents of either sign under suppression of the nonjunctional currents flowing through K+ and Ca2+ channels in the cell membrane. They did not exhibit any voltage-gated Na+ currents. Cells identified by LY fills were typically slender. As the difference between the test potential and the resting potential increased, 13 out of 37 cells exhibited symmetrically voltage- and time-dependent current decline on either sign at the resting potential. The symmetric current profile suggests that the current may be driven and modulated by the junctional potential difference between the clamping cell and its neighbors. The remaining 24 cells did not exhibit voltage dependency. A gap junction channel blocker, halothane, suppressed the currents. A decrease in extracellular pH reduced coupling currents and its increase enhanced them. Dopamine, cAMP, and retinoic acid did not influence coupling currents. Injection of biocytin into single progenitor cells revealed strong tracer coupling, which was restricted in the marginal region. Immature ganglion cells closely located to the retinal margin exhibited voltage-gated Na+ currents. They did not reveal apparent tracer coupling. These results demonstrate that the marginal progenitor cells couple with each other via gap junctions, and communicate biochemical molecules, which may subserve or interfere with cellular differentiation. © 2001 John Wiley & Sons, Inc. J Neurobiol 48: 204,214, 2001 [source]

Role for cAMP-protein kinase A signalling in augmented neutrophil adhesion and chemotaxis in sickle cell disease

EUROPEAN JOURNAL OF HAEMATOLOGY, Issue 4 2007
Andreia A. Canalli
Abstract The significance of the leukocyte in sickle cell disease (SCD) pathophysiology is becoming increasingly recognised; we sought to examine whether the chemotactic properties of neutrophils of SCD individuals may be altered and, further, to better understand the signalling events that mediate altered SCD neutrophil function. Adhesion to immobilised fibronectin (FN) and chemotaxis of control and SCD neutrophils were assessed using in vitro static adhesion assays and 96-well chemotaxis chamber assays. Adhesion assays confirmed a significantly higher basal adhesion of SCD neutrophils to FN, compared with control neutrophils. Chemotaxis assays established, for the first time, that SCD neutrophils demonstrate greater spontaneous migration and, also, augmented migration in response to IL-8, when compared with control neutrophils. Co-incubation of SCD neutrophils with KT5720 (an inhibitor of PKA) abrogated increased basal SCD neutrophil adhesion, spontaneous chemotaxis and IL-8-stimulated chemotaxis. Stimulation of SCD neutrophils with IL-8 also significantly augmented SCD neutrophil adhesion to FN with a concomitant increase in cAMP levels and this increase in adhesion was abolished by KT5720. Interestingly, the adhesive properties of neutrophils from SCD individuals on hydroxyurea therapy were not significantly altered and results indicate that a reduction in intracellular cAMP may contribute to lower the adhesive properties of these cells. Data indicate that up-regulated cAMP signalling plays a significant role in the altered adhesive and migratory properties in SCD neutrophils. Such alterations may have important implications for the pathophysiology of the disease and the cAMP-PKA pathway may represent a therapeutic target for the abrogation of altered leukocyte function. [source]

ICER/CREM-mediated transcriptional attenuation of IL-2 and its role in suppression by regulatory T cells

EUROPEAN JOURNAL OF IMMUNOLOGY, Issue 4 2007
Josef Bodor Dr.
Abstract Here, we report that inducible cAMP early repressor/cAMP response element modulator (ICER/CREM) is induced early in CD25+CD4+ regulatory T cell (TR) assays mainly in activated Foxp3, effector T cells and this induction correlates with sharp decrease in number of IL-2-expressing T cells. Importantly, RNAi targeting of ICER/CREM in responder CD25,CD4+ T cells antagonizes TR -mediated suppression. Moreover, forced expression of Foxp3 in naive CD25, T cells induces constitutive expression of ICER/CREM in T cells with a regulatory phenotype. Foxp3 facilitates expression of ICER/CREM both in Foxp3 transductants as well as CD25, responder T cells suggesting that induction of TR function in suppression assays may utilize contact-dependent interaction. Indeed, CTLA-4 blockade or use of B7-deficient CD25, responder T cells prevents ICER/CREM accumulation and leads to the rescue of IL-2 expression. Therefore, we propose that CTLA-4 binding to B7 ligands expressed on activated ligand-bearing Foxp3, effector T cells results in ICER/CREM-mediated transcriptional attenuation of IL-2. Collectively, these data suggest that Foxp3 expression in TR cells imposes suppression in contact-dependent fashion by induction of constitutive ICER/CREM expression in activated CD25+ Foxp3, T cell effectors thus preventing them from producing IL-2. [source]

Pituitary adenylyl cyclase-activating polypeptide controls the proliferation of retinal progenitor cells through downregulation of cyclin D1

EUROPEAN JOURNAL OF NEUROSCIENCE, Issue 3 2010
Brian Njaine
Abstract During retinal development, cell proliferation and exit from the cell cycle must be precisely regulated to ensure the generation of the appropriate numbers and proportions of the various retinal cell types. Previously, we showed that pituitary adenylyl cyclase-activating polypeptide (PACAP) exerts a neuroprotective effect in the developing retina of rats, through the cAMP,cAMP-dependent protein kinase (protein kinase A) (PKA) pathway. Here, we show that PACAP also regulates the proliferation of retinal progenitor cells. PACAP, PACAP-specific receptor (PAC1), and the receptors activated by both PACAP and vasoactive intestinal peptide (VIP), VPAC1 and VPAC2, are expressed during embryonic and postnatal development of the rat retina. Treatment of retinal explants with PACAP38 reduced the incorporation of [3H]thymidine as well as the number of 5-bromo-2,-deoxyuridine-positive and cyclin D1-positive cells. Pharmacological experiments indicated that PACAP triggers this antiproliferative effect through the activation of both PAC1 and VPACs, and the cAMP,PKA pathway. In addition, PACAP receptor activation decreased both cyclin D1 mRNA and protein content. Altogether, the data support the hypothesis that PACAP is a cell-extrinsic regulator with multiple roles during retinal development, including the regulation of proliferation in a subpopulation of retinal progenitor cells. [source]

Adenylyl cyclase encoded by AC78C participates in sugar perception in Drosophila melanogaster

EUROPEAN JOURNAL OF NEUROSCIENCE, Issue 10 2008
Kohei Ueno
Abstract In gustatory receptor neurons (GRNs) in Drosophila melanogaster, Gr5a and one of the Gr64s encode sugar receptors with seven transmembrane domains. Previously, we have shown that the responses to various sugars are depressed in DGs, mutant flies (Ueno et al., 2006). Because DGs, is a homolog of Gs, we hypothesized that the sugar receptors are coupled to adenylyl cyclase (AC) in Drosophila. The aim of this study was to identify the AC that participates in sugar perception. Here, we found that an AC inhibitor, MDL-12330A, depressed the response in GRNs to trehalose as well as sucrose; that an AC gene, AC78C, was expressed in the sugar-sensitive GRNs; that RNAi against AC78C depressed the electrical response in GRNs to sucrose; and that the sugar response in GRNs, as well as sugar intake in a behavioral assay in an AC78C mutant, was depressed at low sugar concentrations. We conclude that AC78C, via cAMP, participates in the sugar-taste signaling pathway at the low concentration range. [source]

MAP-kinase-activated protein kinase 2 expression and activity is induced after neuronal depolarization

EUROPEAN JOURNAL OF NEUROSCIENCE, Issue 4 2008
Tobias Thomas
Abstract Mitogen-activated protein kinase-activated protein kinase (MK)2 is one of several downstream targets of p38 mitogen-activated protein kinase and has a well documented role in inflammation. Here, we describe a possible new function of MK2. We show that triggering depolarization by potassium chloride or increasing the cellular cAMP by forskolin treatment led to elevated levels of expression and activity of mouse MK2. In both treatments, the kinase inhibitor H89 completely prevented the up-regulation of MK2 at the transcript level. By the use of different cell lines we demonstrated that the induction of MK2 expression is characteristic of neuronal cells and is absent in fibroblasts, macrophages and kidney cells. In vivo, induction of a status epilepticus by systemic administration of the chemoconvulsant kainic acid resulted in markedly reduced neurodegeneration in the pyramidal layer of the hippocampus, dentate gyrus and hilus of MK2-deficient mice compared with wild-type mice. Together, our data suggest a possible role of MK2 in the cellular response after neuronal depolarization, in particular in excitotoxicity. [source]

Plasma membrane Ca2+ -ATPase in the cilia of olfactory receptor neurons: possible role in Ca2+ clearance

EUROPEAN JOURNAL OF NEUROSCIENCE, Issue 9 2007
Karen Castillo
Abstract Olfactory sensory neurons respond to odorants increasing Ca2+ concentrations in their chemosensory cilia. Calcium enters the cilia through cAMP-gated channels, activating Ca2+ -dependent chloride or potassium channels. Calcium also has a fundamental role in odour adaptation, regulating cAMP turnover rate and the affinity of the cyclic nucleotide-gated channels for cAMP. It has been shown that a Na+/Ca2+ exchanger (NCX) extrudes Ca2+ from the cilia. Here we confirm previous evidence that olfactory cilia also express plasma membrane Ca2+ -ATPase (PMCA), and show the first evidence supporting a role in Ca2+ removal. Both transporters were detected by immunoblot of purified olfactory cilia membranes. The pump was also revealed by immunocytochemistry and immunohistochemistry. Inside-out cilia membrane vesicles transported Ca2+ in an ATP-dependent fashion. PMCA activity was potentiated by luminal Ca2+ (K0.5 = 670 nm) and enhanced by calmodulin (CaM; K0.5 = 31 nm). Both carboxyeosin (CE) and calmidazolium reduced Ca2+ transport, as expected for a CaM-modulated PMCA. The relaxation time constant (,) of the Ca2+ -dependent Cl, current (272 ± 78 ms), indicative of luminal Ca2+ decline, was increased by CE (2181 ± 437 ms), by omitting ATP (666 ± 49 ms) and by raising pH (725 ± 65 ms), suggesting a role of the pump on Ca2+ clearance. Replacement of external Na+ by Li+ had a similar effect (, = 442 ± 8 ms), confirming the NCX involvement in Ca2+ extrusion. The evidence suggests that both Ca2+ transporters contribute to re-establish resting Ca2+ levels in the cilia following olfactory responses. [source]

Peripheral antinociceptive effect of pertussis toxin: activation of the arginine/NO/cGMP/PKG/ ATP-sensitive K+ channel pathway

EUROPEAN JOURNAL OF NEUROSCIENCE, Issue 4 2006
Gerly A. C. Brito
Abstract The aim of the present study was to determine the effect of pertussis toxin (PTX) on inflammatory hypernociception measured by the rat paw pressure test and to elucidate the mechanism involved in this effect. In this test, prostaglandin E2 (PGE2) administered subcutaneously induces hypernociception via a mechanism associated with neuronal cAMP increase. Local intraplantar pre-treatment (30 min before), and post-treatment (5 min after) with PTX (600 ng/paw1, in 100 µL) reduced hypernociception induced by prostaglandin E2 (100 ng/paw, in 100 µL, intraplantar). Furthermore, local intraplantar pre-treatment (30 min before) with PTX (600 ng/paw, in 100 µL) reduced hypernociception induced by DbcAMP, a stable analogue of cAMP (100 µg/paw, in 100 µL, intraplantar), which indicates that PTX may have an effect other than just Gi/G0 inhibition. PTX-induced analgesia was blocked by selective inhibitors of nitric oxide synthase (L-NMMA), guanylyl cyclase (ODQ), protein kinase G (KT5823) and ATP-sensitive K+ channel (Kir6) blockers (glybenclamide and tolbutamide). In addition, PTX was shown to induce nitric oxide (NO) production in cultured neurons of the dorsal root ganglia. In conclusion, this study shows a peripheral antinociceptive effect of pertussis toxin, resulting from the activation of the arginine/NO/cGMP/PKG/ATP-sensitive K+ channel pathway. [source]

Regulated expression of HCN channels and cAMP levels shape the properties of the h current in developing rat hippocampus

EUROPEAN JOURNAL OF NEUROSCIENCE, Issue 1 2006
Rainer Surges
Abstract The hyperpolarization-activated current (Ih) contributes to intrinsic properties and network responses of neurons. Its biophysical properties depend on the expression profiles of the underlying hyperpolarization-activated, cyclic nucleotide-gated (HCN) channels and the presence of cyclic AMP (cAMP) that potently and differentially modulates Ih conducted by HCN1, HCN2 and/or HCN4. Here, we studied the properties of Ih in hippocampal CA1 pyramidal cells, the developmental evolution of the HCN-subunit isoforms that contribute to this current, and their interplay with age-dependent free cAMP concentrations, using electrophysiological, molecular and biochemical methods. Ih amplitude increased progressively during the first four postnatal weeks, consistent with the observed overall increased expression of HCN channels. Activation kinetics of the current accelerated during this period, consonant with the quantitative reduction of mRNA and protein expression of the slow-kinetics HCN4 isoform and increased levels of HCN1. The sensitivity of Ih to cAMP, and the contribution of the slow component to the overall Ih, decreased with age. These are likely a result of the developmentally regulated transition of the complement of HCN channel isoforms from cAMP sensitive to relatively cAMP insensitive. Thus, although hippocampal cAMP concentrations increased over twofold during the developmental period studied, the coordinated changes in expression of three HCN channel isoforms resulted in reduced effects of this signalling molecule on neuronal h currents. [source]