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Possible Functions (possible + function)
Selected AbstractsUptake of Calcium by Mitochondria: Transport and Possible FunctionIUBMB LIFE, Issue 3-5 2001Thomas E. Gunter Abstract Vertebrate mitochondria contain a complex system for transport of Ca 2+ and related ions, consisting of two saturable modes of Ca 2+ influx and two separate, saturable mechanisms of Ca 2+ efflux. The characteristics of the mechanisms of Ca 2+ uptake, the uniporter and the RaM, are discussed here and suggestions are made about how the mechanisms may work together and separately to mediate the two physiological roles with which they are most commonly associated - control of the rate of cellular ATP production and induction of the permeability transition and apoptosis. It is argued that more subtlety of control of intramitochondrial free Ca 2+ concentration ([Ca 2+ ] m ) must be used by the uniporter and the RaM to fulfill their physiological roles than has been commonly recognized. This is because an increase in [Ca 2+ ] m is associated with both increased production of ATP which supports the continued life of the cell and with induction of the permeability transition and possibly apoptosis, which leads to cell death. The saturable mechanisms of mitochondrial Ca 2+ efflux and the Ca 2+ -induced mitochondrial permeability transition, which can transport Ca 2+ as well as other ions and molecules and is often considered as a Ca 2+ transport mechanism, are being reviewed separately. [source] Abundant Tissue Butyrylcholinesterase and Its Possible Function in the Acetylcholinesterase Knockout MouseJOURNAL OF NEUROCHEMISTRY, Issue 3 2000Bin Li Abstract: We have described recently an acetylcholinesterase (AChE) knockout mouse. While comparing the tissue distribution of AChE and butyrylcholinesterase (BChE), we found that extraction buffers containing Triton X-100 strongly inhibited mouse BChE activity. In contrast, buffers with Tween 20 caused no inhibition of BChE. Conventional techniques grossly underestimated BChE activity by up to 15-fold. In Tween 20 buffer, the intestine, serum, lung, liver, and heart had higher BChE than AChE activity. Only brain had higher AChE than BChE activity in AChE +/+ mice. These findings contradict the dogma, based mainly on observations in Triton X-100 extracts, that BChE is a minor cholinesterase in animal tissues. AChE +/- mice had 50% of normal AChE activity and AChE -/- mice had none, but all mice had similar levels of BChE activity. BChE was inhibited by Triton X-100 in all species tested, except rat and chicken. Inhibition was reversible and competitive with substrate binding. The active site of rat BChE was unique, having an arginine in place of leucine at position 286 (human BChE numbering) in the acyl-binding pocket of the active site, thus explaining the lack of inhibition of rat BChE by Triton X-100. The generally high levels of BChE activity in tissues, including the motor endplate, and the observation that mice live without AChE, suggest that BChE has an essential function in nullizygous mice and probably in wild-type mice as well. [source] Evidence for the importance of odour-perception in the parasitoid Rhopalicus tutela (Walker) (Hym., Pteromalidae)JOURNAL OF APPLIED ENTOMOLOGY, Issue 6 2001E. M. Pettersson Possible host location mechanisms in the chalcid wasp Rhopalicus tutela (Walker) (Hym., Pteromalidae), a parasitoid of the eight-spined spruce bark beetle, Ips typographus (L.) (Col., Scolytidae), were examined. This was carried out in order to repeat and complement former studies on parallel parasitoid,scolytid systems that had contradictory results. Morphological examinations of the parasitoid antennae were made using both scanning and transmission electron microscopy. Possible functions of the sensilla placodea (multiporous plate sensillum), and other sensilla present on the antennae, have been indicated. For the first time, the placoid sensilla in a pteromalid parasitoid have shown porous walls and numerous innervations, which are typical characteristics for chemoreceptors. Previously the placoid sensilla have been suggested to be an infrared receptor. In order to test the chemoreceptive ability of R. tutela females and males, a synthetic reference blend was analysed by combined gas chromatography and electroantennographic detector (GC-EAD). Their sensitivity to host-related volatiles (such as certain pheromone components and oxygenated monoterpenes) was significantly greater than that for host-tree-related compounds (monoterpene hydrocarbons). Employing an infrared thermo-scanner, the current study failed to detect ,hot spots' associated with susceptible hosts beneath the bark. Results from electrophysiology and electron microscopy revealed clear odour-perceptive functions of the parasitoid antennae. These results strongly support the major importance of volatiles in host location by the bark beetle parasitoid R. tutela. [source] Developmental anatomy of reeler mutant mouseDEVELOPMENT GROWTH & DIFFERENTIATION, Issue 3 2009Yu Katsuyama The reeler mouse is one of the most famous spontaneously occurring mutants in the research field of neuroscience, and this mutant has been used as a model animal to understand mammalian brain development. The classical observations emphasized that laminar structures of the reeler brain are highly disrupted. Molecular cloning of Reelin, the gene responsible for reeler mutant provided insights into biochemistry of Reelin signal, and some models had been proposed to explain the function of Reelin signal in brain development. However, recent reports of reeler found that non-laminated structures in the central nervous system are also affected by the mutation, making function of Reelin signal more controversial. In this review, we summarized reported morphological and histological abnormalities throughout the central nervous system of the reeler comparing to those of the normal mouse. Based on this overview of the reeler abnormalities, we discuss possible function of Reelin signal in the neuronal migration and other morphological events in mouse development. [source] Asymmetric formation and possible function of the primary pore canal in plutei of Temnopleurus hardwickiDEVELOPMENT GROWTH & DIFFERENTIATION, Issue 4 2003Yoshinobu Hara The development and possible function of the primary pore canal (PPC) in plutei of the sea urchin Temnopleurus hardwicki was examined by immunochemistry, electron microscopy and microsurgery. Left and right PPC that extended from coelomic sacs in plutei contained a bundle of cilia with a 9 + 2 structure that was initially detected as a group of anti-acetylated tubulin antibody-binding granules in the epithelium of coelomic sacs in 28 h postfertilization (PF) prism larvae. The granules extended to be a bundle of fibers toward the larval dorsal surface, concurrent with formation of the PPC on both sides, over the next 4 h. The cilia in both PPC beat actively. However, the PPC on the right side disappeared by approximately 55 h PF, establishing left,right asymmetry by 60 h PF (the four-arm pluteus stage). The numbers of cilia in the left and right PPC in 56 h PF plutei were five and eight, respectively. Microsurgical removal of the coelomic sac from both sides or the left side only from 26 h PF prism larvae decreased body width to 64 and 91% of normal width by 50 h PF pluteus stage, respectively, whereas that of the right PPC did not. These observations suggest that PPC contribute to the maintenance of normal body width, and that there is asymmetrical activity between the left and right PPC. [source] Ultrastructure of the seminal receptacle and the dimorphic sperm in the commensal bivalve Mysella bidentata (Veneroida; Galeommatoidea; Montacutidae)ACTA ZOOLOGICA, Issue 2 2001Ĺse Jespersen Abstract Jespersen, Ĺ. and Lützen, J. 2001. Ultrastructure of the seminal receptacle and the dimorphic sperm in the commensal bivalve Mysella bidentata (Veneroida: Galeommatoidea: Montacutidae). ,Acta Zoologica (Stockholm) 82: 107,115 The seminal receptacle and the euspermatozoa and paraspermatozoa of Mysella bidentata were examined at an ultrastructural level and the results were compared with earlier findings of the same and other species of the Montacutidae. The euspermatozoon has a slender 13 µm long nucleus and a 1.1 µm long bullet-shaped acrosome. The acrosome of the paraspermatozoon is almost identical in ultrastructure to that of the euspermatozoa but is longer (1.9 µm) and more slender and is bent at an angle to the diminutive nucleus (1.1 µm long). The unpaired seminal receptacle is lined by a heavily ciliated epithelium and a non-ciliated epithelium with short and broad microvilli. Euspermatozoa only are stored in the receptacle. They are densely packed and orientated with their heads towards the non-ciliated epithelium. In this position they develop numerous extremely fine microvilli from the acrosome which apparently serve to attach them to the epithelial microvillar surface. Stored sperm may presumably remain functional for at least six months. A possible function of paraspermatozoa could be to clump sperm into sperm bags to keep them in suspension. [source] Female Attraction to Conspecific Chemical Cues in the Palmate Newt Triturus helveticusETHOLOGY, Issue 8 2005Jean Secondi Although chemosignals are largely used in sexual communication in urodeles, olfactometer studies in newts provided contrasting results about the sex specificity of female behavioural responses. Because long-range sexual advertisement is believed to be costly, some species might restrain this activity to close interactions with conspecifics. We tested chemical-mediated sexual attraction in female palmate newt (Triturus helveticus) by measuring the attraction to male and female odours in a linear water olfactometer. Unexpectedly, females were attracted towards conspecifics regardless of sex. They did not show attraction towards Limnaea stagnalis, a common sympatric aquatic gastropod. These results do not support the use of long-range male sexual signalling in the palmate newt. Instead, conspecific attraction is likely to promote aggregation of males and females in breeding ponds. Observations in the field and in the laboratory tend to support the aggregative behaviour of this species. We discuss the possible function of conspecific attraction in this context. Heading towards any conspecific would increase the probability of finding potential mates. Chemical cues do not need to be sex-specific at that stage so that long-range sexual advertisement might be unnecessary. This work emphasizes the need for studies investigating the evolutionary relationships between sexual signalling systems and population-distribution patterns. [source] Expression of the NKG2D ligand UL16 binding protein-1 (ULBP-1) on dendritic cellsEUROPEAN JOURNAL OF IMMUNOLOGY, Issue 1 2006David Schrama Abstract Innate and adaptive immunity have not evolved separately. In this regard, the NKG2D molecule first identified on NK cells and classified as an activating NK cell receptor is also an important receptor for CD8+ T,cells. Functional analyses of human NKG2D and its ligands, i.e. UL16 binding proteins (ULBP) and MHC class I chain-related (MIC), have so far focused on immune cell-target cell situations because of the expression of NKG2D ligands on infected, stressed or transformed cells. Here, however, we address a possible function of NKG2D/ULBP-1 during the initiation of T cell responses. ULBP-1 can be detected on mature dendritic cells both in situ in the T cell areas of lymph nodes as well as in vitro after artificial maturation. FCM analysis further demonstrated that although NKG2D is expressed to some degree on all analyzed T cell subsets from peripheral blood, in vitro stimulation of T cells results in up-regulation of NKG2D on proliferating T cells. Using the sentinel lymph nodes of primary melanoma as a model for induction of defined T cell responses in vivo, we were able to demonstrate the expression of NKG2D on melanoma-associated antigen-specific T cells. Thus, our results suggest a role for NGK2D-ULBP-1 in the induction or reactivation of T cell responses. [source] The functional properties of the human ether-ŕ-go-go -like (HELK2) K+ channelEUROPEAN JOURNAL OF NEUROSCIENCE, Issue 3 2002Andrea Becchetti Abstract The voltage-dependent K+ channels belonging to the ether-ŕ-go-go family (eag, erg, elk) are widely expressed in the mammalian CNS. Their neuronal function, however, is poorly understood. Among the elk clones, elk2 is the most abundantly expressed in the brain. We have characterized the human ELK2 channel (HELK2) expressed in mammalian cell lines. Moreover, we have detected helk2 mRNA and ELK2-like currents in freshly dissociated human astrocytoma cells. HELK2 was inhibited by Cs+ in a voltage-dependent way (Kd was 0.7 mm, at ,120 mV). It was not affected by Way 123398 (5 µm), dofetilide (10 µm), quinidine (10 µm), verapamil (20 µm), haloperidol (2 µm), astemizole (1 µm), terfenadine (1 µm) and hydroxyzine (30 µm), compounds known to inhibit the biophysically related HERG channel. The crossover of the activation and inactivation curves produced a steady state ,window' current with a peak around ,20 mV and considerably broader than it usually is in voltage-dependent channels, including HERG. Similar features were observed in the ELK2 clone from rat, in the same experimental conditions. Thus, ELK2 channels are active within a wide range of membrane potentials, both sub- and suprathreshold. Moreover, the kinetics of channel deactivation and removal of inactivation was about one order of magnitude quicker in HELK2, compared to HERG. Overall, these properties suggest that ELK2 channels are very effective at dampening the neuronal excitability, but less so at producing adaptation of action potential firing frequency. In addition, we suggest experimental ways to recognize HELK2 currents in vivo and raise the issue of the possible function of these channels in astrocytoma. [source] Reversible inactivation of the hippocampal formation in food-storing black-capped chickadees (Poecile atricapillus)HIPPOCAMPUS, Issue 4 2003Michael W. Shiflett Abstract The role of the hippocampal formation (HF) in memory processing was assessed in food-storing black-capped chickadees (Poecile atricapilla) by reversibly inactivating the HF during different memory tests. The memory tests required birds to remember a location based on spatial cues only, or based on a combination of both spatial and distinct visual cues. Inactivation of the HF impaired short-term spatial memory, but not visual-spatial memory. Inactivation of the HF impaired the retrieval of short-term (15 min) spatial memories, but not long-term (3-h) spatial memories. The pattern of deficits produced by inactivation of the HF in chickadees suggests a possible function of the hippocampal specialization of food-storing birds, as well as extends the notion of functional homology between the avian and mammalian HF. Hippocampus 2003;13:437,444. © 2003 Wiley-Liss, Inc. [source] Theory and applications of the integrated molecular transform and the normalized molecular moment structure descriptors: QSAR and QSPR paradigmsINTERNATIONAL JOURNAL OF QUANTUM CHEMISTRY, Issue 6 2001Stephen P. Molnar Abstract The chemical and mathematical rationalé in the development of the numerically unitary integrated molecular transform (FTm), its analogous electronic (FTe) and charge (FTc) transforms, and the normalized molecular moment (Mn), and its analogous electronic (Me) and charge (Mc) moment as molecular structure descriptors are presented. The reported application and utilization of these indices for predictive capability correlations of structure with physicochemical, pharmacological, and thermodynamic properties are reviewed. The further use of these descriptors in considerations of chemical similarity is noted, as is their capability for searching compound databases whose contents include the noted calculated indices. Their potential for characterizing peptides, proteins, and oligomers as well as their possible function in mathematical models is discussed. © 2001 John Wiley & Sons, Inc. Int J Quantum Chem, 2001 [source] Matrix metalloproteinase (MMP)-12 regulates MMP-9 expression in interleukin-1,-treated articular chondrocytesJOURNAL OF CELLULAR BIOCHEMISTRY, Issue 6 2008Hwanhee Oh Abstract Limited information is available on the expression and role of matrix metalloproteinase (MMP)-12 in chondrocytes. We characterized the expression mechanism of MMP-12 and possible function in chondrocytes. Interleukin (IL)-1, induced the expression and activation of MMP-12 in primary culture chondrocytes and cartilage explants via mitogen-activated protein (MAP) kinase signaling pathways. Among MAP kinases, extracellular signal-regulated kinase and p38 kinase are necessary for MMP-12 expression, whereas c-jun N-terminal kinase is required for the activation of MMP-12. The possibility that MMP-12 acts as a modulator of other MMP was examined. MMP-12 alone did not affect other MMP expressions. However, MMP-12 enhanced expression and activation of MMP-9 in the presence of IL-1,. Our results indicate that IL-1, in chondrocytes induces the expression and activation of MMP-12, which, in turn, augments MMP-9 expression and activation. J. Cell. Biochem. 105: 1443,1450, 2008. © 2008 Wiley-Liss, Inc. [source] Poster Sessions AP01: Gene Expression and RegulationJOURNAL OF NEUROCHEMISTRY, Issue 2001J. M. Calandria The formation of Cortico-Thalamic projections requires the precise spatial and temporal expression of proteins that are involved in the different stages of synaptogenesis. We reasoned that the underlying molecular mechanism of this process is the differential expression of genes that code for stage specific proteins. Our research objective was to identify the differential expressed mRNAs during the main stages of synapses formation, which starts at embryonic day 12 (E12) and finishes on the first postnatal days in the rat. We approach this problem using Differential Display technique on three distinct ages of rat cerebral cortex that were: E13, E18 and postnatal day 0 (P0). We found 80 differential bands using 54 random primers and 18 of them were cloned and sequenced. The sequence analysis showed among others, a cDNA fragment highly homologous with the human A Kinase Anchoring Protein 450/350 also called CG-NAP. We found that this cDNA fragment homologous to AKAP was up regulated at E15 when cortical cells are undergoing active axogenesis. The expression pattern of this cDNA was confirmed by Real Time PCR. Our findings suggest a possible function for AKAP 450 in the regulation of the state of phosphorylation of centrosomal components during the initial stages of synapses formation during the establishment of Cortico-Thalamic connection. [source] Stroke Injury in Rats Causes an Increase in Activin A Gene Expression Which is Unaffected by Oestradiol TreatmentJOURNAL OF NEUROENDOCRINOLOGY, Issue 2 2006M. Böttner Abstract Activins are members of the transforming growth factor-, superfamily that exert neurotrophic and neuroprotective effects on various neuronal populations. To determine the possible function of activin in stroke injury, we assessed which components of the activin signalling pathway were modulated in response to middle cerebral artery occlusion (MCAO). Furthermore, because oestradiol replacement protects against MCAO-induced cell death, we explored whether oestradiol replacement influences activin gene expression. Female Sprague-Dawley rats underwent permanent MCAO and the expression of activins and their corresponding receptors was determined by semiquantitative reverse transcriptase-polymerase chain reaction at 24 h after onset of ischaemia. We observed up-regulation of activin ,A and activin type I receptor A mRNA in response to injury. Dual-label immunocytochemistry followed by confocal z-stack analysis showed that the activin A expressing cells comprised neurones. Next, we monitored the time course of activin ,A mRNA expression in oestradiol- or vehicle-treated rats at 4, 8, 16 and 24 h after MCAO via in situ hybridisation. Starting at 4 h after injury, activin ,A mRNA was up-regulated in cortical and striatal areas in the ipsilateral hemisphere. Activin ,A mRNA levels in the cortex increased dramatically with time and were highest at 24 h after the insult, and oestradiol replacement did not influence this increase. [source] Protease-activated receptor-induced Akt activation , regulation and possible functionJOURNAL OF THROMBOSIS AND HAEMOSTASIS, Issue 12 2007J. C. RESÉNDIZ Summary.,Background:,Thrombin induces the activation of the platelet serine/threonine kinase Akt. Akt activation is dependent on its phosphorylation at Thr308 and Ser473. The mechanism by which thrombin induces Akt phosphorylation is controversial, as is the role of Akt in platelet function. Objectives:,To investigate how protease-activated receptors (PARs) stimulate Akt and the role that Akt plays in human platelet function. Methods:,Platelets were stimulated through PAR1 or PAR4. Specific inhibitors were used to evaluate, by Western blotting, signaling pathways regulating Akt phosphorylation, and the role of activated Akt was evaluated by aggregometry and flow cytometry. Results:,Phospholipase C (PLC) controls Akt phosphorylation elicited by PARs. Stimulation of PAR1 or PAR4 resulted in rapid Akt phosphorylation, independently of secreted ADP and phosphatidylinositol-3-kinase (PI3K) activation. Akt phosphorylation ,60 s after PAR1 stimulation became entirely dependent on the purinergic receptor P2Y12 and the activation of PI3K. In contrast, PAR4 partially sustained Akt phosphorylation independently of P2Y12 and PI3K for up to 300 s. Pharmacologic inhibition of Akt reduced P-selectin expression and fibrinogen binding in platelets stimulated through PAR1, and delayed platelet aggregation in response to submaximal PAR1 or PAR4 stimulation, although aggregation at 300 s was unaffected. Conclusions:,Platelet PAR stimulation causes rapid Akt phosphorylation downstream of PLC, whereas with continuous stimulation, ADP and PI3K are required for maintaining Akt phosphorylation. Activated Akt regulates platelet function by modulating secretion and ,IIb,3 activation. [source] Foot-thumping as an alarm signal in macropodoid marsupials: prevalence and hypotheses of functionMAMMAL REVIEW, Issue 4 2006TANIA A. ROSE ABSTRACT 1Alarm signalling as a means to reduce predation risk is an important component of the behavioural repertoire of many species. It has previously been noted that many of the macropodoid marsupials (kangaroos, wallabies and rat-kangaroos) produce a foot-thump, an audible signal created by striking the ground with one or both feet, that is most likely an alarm signal. 2The prevalence of foot-thumping within the macropodoids and hypotheses of its function as an alarm signal have been poorly documented. To address this issue, we investigate the prevalence of foot-thumping in macropodoids and interpret possible function according to current alarm signalling theory. Evidence for foot-thumping was found in almost all macropodoids. In light of this, the behaviour appears to be a conservative trait that may have arisen alongside or followed the evolution of bipedal locomotion, and suggests that this trait carries significant benefits that transcend ecological and predation differences among species. 3Nine alarm signal hypotheses were explored in order to determine the function of foot-thumping in macropodoid marsupials. However, the existing evidence for consistent function remains inconclusive. Therefore, a series of predictions were developed to provide the foundation for future research to investigate more thoroughly the function of foot-thumping in macropodoid marsupials. [source] Vesicle amine transport protein-1 (VAT-1) is upregulated in glioblastomas and promotes migrationNEUROPATHOLOGY & APPLIED NEUROBIOLOGY, Issue 4 2009S. Mertsch Aim:,Diffuse invasion of single-glioma cells is the main obstacle to successful therapy of these tumours. After identifying vesicle amine transport protein-1 (VAT-1) as being upregulated in invasive human gliomas, we study its possible function in glioblastoma cell migration. Methods:,Based on data obtained from previous oligonucleotide arrays, we investigated expression of VAT-1 in glioblastoma tissue and cell lines on mRNA levels using reverse transcriptase PCR. Furthermore, we examined the amount and localization of VAT-1 protein using immunoblotting and immunohistochemistry. Using small interfering RNA technology we repressed VAT-1 expression in human glioma cell lines and analysed their migration using wound healing and transwell migration assays. Results:,Increased VAT-1 mRNA and protein levels were found in glioblastoma tissues and cell lines compared with normal human brain. Small interfering RNA-mediated VAT-1 knockdown led to significantly reduced migration of human glioma cells. Conclusions:,VAT-1 is overexpressed in glioblastomas and functionally involved in glioma cell migration, representing a new component involved in glioma invasion. [source] Properties of plant plasma membrane lipid models , bilayer permeability and monolayer behaviour of glucosylceramide and phosphatidic acid in phospholipid mixturesPHYSIOLOGIA PLANTARUM, Issue 2 2000Anna H. Berglund Phosphatidic acid (PA) and glucosylceramide (Cer), constituents of plant plasma membranes, were used in interaction studies with the major plasma membrane lipid components, phosphatidylcholine (PC) and phosphatidylethanolamine (PE). With molecular species combinations, representative for plant plasma membranes, packing conditions during compression of monolayers of PC/PE mixtures with different amounts of PA or Cer added, were investigated. In contrast to the behaviour of single PA or single Cer, which exhibited condensed compression curves, as compared with curves representative for phosphoglycerides, the triple mixtures of PC/PE with PA or Cer showed markedly expanded monolayer films. These data were evaluated as a spontaneous heterogeneous dispersion of PA and Cer in the PC/PE mixture. Membrane vesicles produced with different amounts of PA added to a PC/PE mixture of 1:1 (mol/mol) had an almost linear increase in permeability for glucose (chosen as a common polar low-molecular mass metabolite) with increasing percentage PA. The presence of PA in plasma membranes and its possible function are discussed in relation to recent reports on anionic protein-lipid interactions. PC/PE vesicles with different amounts of Cer added did not influence the permeability for glucose at 2.5 and 5 mol%, but did so, significantly, at 7.5 and 9 mol%. [source] Lutein epoxide cycle, light harvesting and photoprotection in species of the tropical tree genus IngaPLANT CELL & ENVIRONMENT, Issue 4 2008SHIZUE MATSUBARA ABSTRACT Dynamics and possible function of the lutein epoxide (Lx) cycle, that is, the reversible conversion of Lx to lutein (L) in the light-harvesting antennae, were investigated in leaves of tropical tree species. Photosynthetic pigments were quantified in nine Inga species and species from three other genera. In Inga, Lx levels were high in shade leaves (mostly above 20 mmol mol,1 chlorophyll) and low in sun leaves. In Virola surinamensis, both sun and shade leaves exhibited very high Lx contents (about 60 mmol mol,1 chlorophyll). In Inga marginata grown under high irradiance, Lx slowly accumulated within several days upon transfer to deep shade. When shade leaves of I. marginata were briefly exposed to the sunlight, both violaxanthin and Lx were quickly de-epoxidized. Subsequently, overnight recovery occurred only for violaxanthin, not for Lx. In such leaves, containing reduced levels of Lx and increased levels of L, chlorophyll fluorescence induction showed significantly slower reduction of the photosystem II electron acceptor, QA, and faster formation as well as a higher level of non-photochemical quenching. The results indicate that slow Lx accumulation in Inga leaves may improve light harvesting under limiting light, while quick de-epoxidation of Lx to L in response to excess light may enhance photoprotection. [source] Extrusomes in Ciliates: Diversification, Distribution, and Phylogenetic ImplicationsTHE JOURNAL OF EUKARYOTIC MICROBIOLOGY, Issue 6 2003GIOVANNA ROSATI ABSTRACT. Exocytosis is, in all likelihood, an important communication method among microbes. Ciliates are highly differentiated and specialized micro-organisms for which versatile and/or sophisticated exocytotic organelles may represent important adaptive tools. Thus, in ciliates, we find a broad range of different extrusomes, i.e ejectable membrane-bound organelles. Structurally simple extrusomes, like mucocysts and cortical granules, are widespread in different taxa within the phylum. They play the roles in each case required for the ecological needs of the organisms. Then, we find a number of more elaborate extrusomes, whose distribution within the phylum is more limited, and in some way related to phylogenetic affinities. Herein we provide a survey of literature and our data on selected extrusomes in ciliates. Their morphology, distribution, and possible function are discussed. The possible phylogenetic implications of their diversity are considered. [source] Expression of gp34 (OX40 Ligand) and OX40 on Human T Cell ClonesCANCER SCIENCE, Issue 4 2001Naruhiko Takasawa gp34, which we previously cloned, is a ligand of OX40 (CD 134), a costimulatory molecule involved in T cell activation. To elucidate the role of human OX40/OX40L interaction, we examined the expression of gp34 (OX40L) and OX40 in normal human hematopoietic cells by using flow cytometry. OX40 expression is observed on activated T cells, while OX40L is expressed in antigen-presenting cells. However, cytotoxic T lymphocyte (CTL) clones specific for Epstein-Barr virus (EBV)-transformed autologous lymphoblastic cell lines (LCLs) induced both OX40 and OX40L expression after antigen or T cell receptor (TCR) stimulation. This study suggests a possible function of OX40L/OX40, through T cell-T cell interaction, in the reactivation of memory T cells in an auto-crine manner, with implications for the pathogenesis of viral infections and neoplasms. [source] Histology and ultrastructure of the salivary glands and salivary pumps in the scorpionfly Panorpa obtusa (Mecoptera: Panorpidae)ACTA ZOOLOGICA, Issue 4 2010Shuyu Liu Abstract Liu, S. and Hua, B. 2009. Histology and ultrastructure of the salivary glands and salivary pumps in the scorpionfly Panorpa obtusa (Mecoptera: Panorpidae). ,Acta Zoologica (Stockholm) 91: 457,465. The morphology, histology and ultrastructure of the salivary glands and salivary pumps in the scorpionfly Panorpa obtusaCheng 1949 were investigated using light microscopy and scanning and transmission electron microscopy. The salivary glands display a distinct sexual dimorphism. The female has only two small sac-like glands located in the prothorax, while the male possesses six long tubular glands extending into the sixth abdominal segment. The male salivary glands can be divided into five distinct regions. The apical long, thin secretory region possesses numerous secretory cells containing large secretory vesicles; the salivary reservoir expands in diameter, accumulating and temporarily storing the saliva in addition to secreting saliva; the constricted region contains prismatic cells with complex infolded plasma membrane; the sac has an internal brush border to absorb water and ions; the common salivary duct contains longitudinal muscles in the male, but not in the female. The salivary pump possesses independent strong dorsal muscles and abundant internal palm spines near its orifice. The anatomy and ultrastructure of the salivary glands and the salivary pump of scorpionflies as well as their possible functions are briefly discussed. [source] Sensillary morphology on the rostral apex and their possible role in prey location behaviour of the carnivorous stinkbug, Eocanthecona furcellata (Wolff) (Heteroptera: Pentatomidae)ACTA ZOOLOGICA, Issue 3 2009Pathipati Usha Rani Abstract Eocanthecona furcellata (Wolff), the carnivorous heteropteran, demonstrates interesting feeding mechanisms that suggest the involvement of the antennal and labial tip sensilla. This study was conducted to identify the morphology of various sensilla present on the labial tip of this insect using scanning electron microscopy. Four morphologically different types of trichoid sensilla comprise the largest and most numerous sensilla and occur throughout the surface of the labial tip. Three new and unique types of sensilla were discovered. Long hairs with profusely branched shafts are present at the entrance of the rostral groove. An oval-shaped peg surrounded by sensory hairs with branched shafts and a short, stout peg encircled by a group of long hair-like sensilla was found among the sensilla population of two lobes. The morphology of the new sensilla is given and possible functions of individual receptors are suggested on morphological grounds. [source] Emerging topics in Reelin functionEUROPEAN JOURNAL OF NEUROSCIENCE, Issue 9 2010Eckart Förster Abstract Reelin signalling in the early developing cortex regulates radial migration of cortical neurons. Later in development, Reelin promotes maturation of dendrites and dendritic spines. Finally, in the mature brain, it is involved in modulating synaptic function. In recent years, efforts to identify downstream signalling events induced by binding of Reelin to lipoprotein receptors led to the characterization of novel components of the Reelin signalling cascade. In the present review, we first address distinct functions of the Reelin receptors Apoer2 and Vldlr in cortical layer formation, followed by a discussion on the recently identified downstream effector molecule n-cofilin, involved in regulating actin cytoskeletal dynamics required for coordinated neuronal migration. Next, we discuss possible functions of the recently identified Reelin,Notch signalling crosstalk, and new aspects of the role of Reelin in the formation of the dentate radial glial scaffold. Finally, progress in characterizing the function of Reelin in modulating synaptic function in the adult brain is summarized. The present review has been inspired by a session entitled ,Functions of Reelin in the developing and adult hippocampus', held at the Spring Hippocampal Research Conference in Verona/Italy, June 2009. [source] The tripartite ATP-independent periplasmic (TRAP) transporters of bacteria and archaeaFEMS MICROBIOLOGY REVIEWS, Issue 4 2001David J Kelly Abstract Until recently, extracytoplasmic solute receptor (ESR)-dependent uptake systems were invariably found to possess a conserved ATP-binding protein (the ATP-binding cassette protein or ABC protein), which couples ATP hydrolysis to the translocation of the solute across the cytoplasmic membrane. While it is clear that this class of ABC transporter is ubiquitous in prokaryotes, it is now firmly established that other, unrelated types of membrane transport systems exist which also have ESR components. These systems have been designated tripartite ATP-independent periplasmic (TRAP) transporters, and they form a distinct class of ESR-dependent secondary transporters where the driving force for solute accumulation is an electrochemical ion gradient and not ATP hydrolysis. Currently, the most well characterised TRAP transporter at the functional and molecular level is the high-affinity C4-dicarboxylate transport (Dct) system from Rhodobacter capsulatus. This consists of three proteins; an ESR (DctP) and small (DctQ) and large (DctM) integral membrane proteins. The characteristics of this system are discussed in detail. Homologues of the R. capsulatus DctPQM proteins are present in a diverse range of prokaryotes, both bacteria and archaea, but not in eukaryotes. The deduced structures and possible functions of these homologous systems are described. In addition to the DctP family, other types of ESRs can be associated with TRAP transporters. A conserved family of immunogenic extracytoplasmic proteins is shown to be invariably associated with TRAP systems that contain a large DctQM fusion protein. All of the currently known archaeal systems are of this type. It is concluded that TRAP transporters are a widespread and ancient type of solute uptake system that transport a potentially diverse range of solutes and most likely evolved by the addition of auxiliary proteins to a single secondary transporter. [source] Anatomy and ultrastructure of the reproductive organs in Dactylopodola typhle (Gastrotricha: Macrodasyida) and their possible functions in sperm transferINVERTEBRATE BIOLOGY, Issue 1 2008Alexander Kieneke Abstract. The reproductive anatomy of gastrotrichs is well known for several species, especially for the marine taxon Macrodasyida. However, there is little information on the reproductive organs and the modes of mating and sperm transfer in putative basal taxa, which is necessary for accurate reconstruction of the ground pattern of the Gastrotricha. We present the first detailed morphological investigation of the reproductive system of a putative basal gastrotrich, Dactylopodola typhle, using transmission and scanning electron microscopy, histology, and microscopic observations of living specimens. Dactylopodola typhle is a hermaphrodite that possesses paired female and male gonads, an unpaired uterus with an outlet channel that we call the cervix, and an additional accessory reproductive organ, the so-called caudal organ. We hypothesize that the hollow, secretory caudal organ serves for picking up autospermatozoa (self-sperm), for spermatophore formation, and finally for transferring the autospermatophore to a mating partner. The allospermatophore (foreign spermatophore) is stored within the uterus where fertilization occurs. We think that the mature and fertilized egg is released through the cervix and the dorsolateral female gonopore, and not by rupture of the body wall. Based on the morphology, we provide a plausible hypothesis for spermatophore formation and transfer in D. typhle. Preliminary phylogenetic considerations indicate that the stem species of Macrodasyida, perhaps that of all Gastrotricha, had paired ovaries and paired testes, an unpaired uterus, and only one accessory reproductive organ. [source] Neurotrophins and the immune systemJOURNAL OF ANATOMY, Issue 1 2003José A. Vega Abstract The neurotrophins are a family of polypeptide growth factors that are essential for the development and maintenance of the vertebrate nervous system. In recent years, data have emerged indicating that neurotrophins could have a broader role than their name might suggest. In particular, the putative role of NGF and its receptor TrkA in immune system homeostasis has become a much studied topic, whereas information on the other neurotrophins is scarce in this regard. This paper reviews what is known about the expression and possible functions of neurotrophins and their receptors in different immune tissues and cells, as well as recent data obtained from studies of transgenic mice in our laboratory. Results from studies to date support the idea that neurotrophins may regulate some immune functions. They also play an important role in the development of the thymus and in the survival of thymocytes. [source] PARP-3 associates with polycomb group bodies and with components of the DNA damage repair machineryJOURNAL OF CELLULAR BIOCHEMISTRY, Issue 2 2007M. Rouleau Abstract Poly(ADP-ribose) polymerase 3 (PARP-3) is a novel member of the PARP family of enzymes that synthesize poly(ADP-ribose) on themselves and other acceptor proteins. Very little is known about this PARP, which is closely related to PARP-1 and PARP-2. By sequence analysis, we find that PARP-3 may be expressed in two isoforms which we studied in more detail to gain insight into their possible functions. We find that both PARP-3 isoforms, transiently expressed as GFP or FLAG fusions, are nuclear. Detection of endogenous PARP-3 with a specific antibody also shows a widespread nuclear distribution, appearing in numerous small foci and a small number of larger foci. Through co-localization experiments and immunoprecipitations, the larger nuclear foci were identified as Polycomb group bodies (PcG bodies) and we found that PARP-3 is part of Polycomb group protein complexes. Furthermore, using a proteomics approach, we determined that both PARP-3 isoforms are part of complexes comprising DNA-PKcs, PARP-1, DNA ligase III, DNA ligase IV, Ku70, and Ku80. Our findings suggest that PARP-3 is a nuclear protein involved in transcriptional silencing and in the cellular response to DNA damage. J. Cell. Biochem. 100: 385,401, 2007. © 2006 Wiley-Liss, Inc. [source] Evidences of a role for eukaryotic translation initiation factor 5A (eIF5A) in mouse embryogenesis and cell differentiationJOURNAL OF CELLULAR PHYSIOLOGY, Issue 2 2010Lucas T. Parreiras-e-Silva Eukaryotic translation initiation factor 5A (eIF5A) has a unique character: the presence of an unusual amino acid, hypusine, which is formed by post-translational modifications. Even before the identification of hypusination in eIF5A, the correlation between hypusine formation and protein synthesis, shifting cell proliferation rates, had already been observed. Embryogenesis is a complex process in which cellular proliferation and differentiation are intense. In spite of the fact that many studies have described possible functions for eIF5A, its precise role is under investigation, and to date nothing has been reported about its participation in embryonic development. In this study we show that eIF5A is expressed at all mouse embryonic post-implantation stages with increase in eIF5A mRNA and protein expression levels between embryonic days E10.5 and E13.5. Immunohistochemistry revealed the ubiquitous presence of eIF5A in embryonic tissues and organs at E13.5 day. Interestingly, stronger immunoreactivity to eIF5A was observed in the stomodeum, liver, ectoderm, heart, and eye, and the central nervous system; regions which are known to undergo active differentiation at this stage, suggesting a role of eIF5A in differentiation events. Expression analyses of MyoD, a myogenic transcription factor, revealed a significantly higher expression from day E12.5 on, both at the mRNA and the protein levels suggesting a possible correlation to eIF5A. Accordingly, we next evidenced that inhibiting eIF5A hypusination in mouse myoblast C2C12 cells impairs their differentiation into myotubes and decreases MyoD transcript levels. Those results point to a new functional role for eIF5A, relating it to embryogenesis, development, and cell differentiation. J. Cell. Physiol. 225: 500,505, 2010. © 2010 Wiley-Liss, Inc. [source] The functions of freezing in the social interactions of juvenile high- and low-aggressive miceAGGRESSIVE BEHAVIOR, Issue 6 2001Daniel J. Bauer Abstract Selectively bred low-aggressive mice are frequently observed to freeze on social contact, despite the fact that this behavior was never a direct target of selection. To elucidate this finding, the present research aimed to identify the possible functions freezing may serve in social interactions. It was hypothesized that freezing may modify social interactions through self-regulatory mechanisms and/or via its modulating effects on the actions of social partners. These hypotheses were evaluated with respect to the sequential changes observed over the course of a 10-min dyadic test in freezing, social reactivity, and approaches among juvenile (24,30-day-old) mice from the NC900 and NC100 high- and low-aggressive lines. Analyses of the patterns of social interactions between subjects and partners revealed two primary results. First, freezing was more than an expression of fear; it also functioned as a regulator of emotional arousal, as suggested by the substantial reduction of reactive behaviors seen in animals that showed high levels of freezing. Second, freezing functioned to facilitate high levels of affiliative social interaction with social partners. The implications of these results for understanding how the differentiation of the NC900 and NC100 occurred within microevolution and development are discussed. Aggr. Behav. 27:463,475, 2001. © 2001 Wiley-Liss, Inc. [source] | |||||||||||||||||||||||||||||||||||||