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Selected AbstractsAntidiabetic and toxicological evaluations of naringenin in normoglycaemic and NIDDM rat models and its implications on extra-pancreatic glucose regulationDIABETES OBESITY & METABOLISM, Issue 11 2008R. R Ortiz-Andrade Aim:, The present investigation was designed to determine the in vivo antidiabetic effect of naringenin (NG) in normoglycaemic and diabetic rat models through blood glucose (GLU) measurements following acute and subchronic time periods. Possible modes of action of NG were investigated and its acute toxicity determined. Methods:, Normoglycaemic and non-insulin-dependent diabetes mellitus (NIDDM) rat models were treated for acute and subchronic (5 days) time periods with 50 mg/kg/day of NG. Blood biochemical profiles were determined after 5 days of the treatment in normoglycaemic and NIDDM rats using commercial kits for GLU, triglycerides (TG), total cholesterol (CHOL) and high-density lipoprotein (HDL). In order to elucidate its antidiabetic mode of action, NG was administered intragastrically and an oral glucose tolerance test performed using GLU and sucrose (2 g/kg) as substrates. The inhibitory effect of a single concentration of NG (10 ,M) on 11,-hydroxysteroid dehydrogenase type 1 (11,-HSD1) activity in vitro was determined. Finally, the preclinical safety and tolerability of NG was determined by toxicological evaluation in mice and rats using Organization for Economic Cooperation and Development (OECD) protocols. Results:, Intragastrically administered NG (50 mg/kg) induced a significant decrease in plasma GLU in normoglycaemic and NIDDM rat models (p < 0.05) following acute and subchronic time periods. After 5 days of administration, NG produced significant diminished blood GLU and TG levels in streptozotocin,nicotinamide,induced diabetic rats. The administration of NG to normal rats significantly increased the levels of TG, CHOL and HDL (p < 0.05). NG (5 and 50 mg/kg) induced a total suppression in the increase of plasma GLU levels after administration of substrates (p < 0.01), but NG did not produce inhibition of ,-glucosidase activity in vitro. However, NG (10 ,M) was shown to inhibit 11,-HSD1 activity by 39.49% in a cellular enzyme assay. Finally, NG showed a Medium Lethal Dose LD50 > 5000 mg/kg and ranking at level five based on OECD protocols. Conclusion:, Our findings suggest that NG may exert its antidiabetic effect by extra-pancreatic action and by suppressing carbohydrate absorption from intestine, thereby reducing the postprandial increase in blood GLU levels. [source] Arsenate and dimethylarsinic acid in drinking water did not affect DNA damage repair in urinary bladder transitional cells or micronuclei in bone marrow,ENVIRONMENTAL AND MOLECULAR MUTAGENESIS, Issue 9 2009Amy Wang Abstract Arsenic is a human skin, lung, and urinary bladder carcinogen, and may act as a cocarcinogen in the skin and urinary bladder. Possible modes of action of arsenic carcinogenesis/cocarcinogenesis include oxidative stress induction and inhibition of DNA damage repair. We investigated the effects of arsenic in drinking water on DNA damage repair in urinary bladder transitional cells and on micronucleus formation in bone marrow. F344 rats were given 100 ppm arsenate [As(V)] or dimethylarsinic acid [DMA(V)] in drinking water for 1 week. The in vivo repair of cyclophosphamide (CP)-induced DNA damage resulting from a single oral gavage of CP, and the in vitro repair of hydrogen peroxide (H2O2)- or formaldehyde-induced DNA damage, resulting from adding H2O2 or formaldehyde into cell medium, were measured by the Comet assay. DMA(V) effects were not observed on either CP-induced DNA damage induction or on DNA repair. Neither DMA(V) nor As(V) increased the H2O2 - or formaldehyde-induced DNA damage, and neither inhibited the repair of H2O2 -induced DNA damage. Neither DMA(V) nor As(V) increased the micronucleus frequency, nor did they elevate micronucleus frequency resulting from CP treatment above the level observed by the treatment with CP alone. These results suggest that arsenic carcinogenesis/cocarcinogenesis in the urinary bladder may not be via DNA damage repair inhibition. To our knowledge this is the first report of arsenic effects on DNA damage repair in the urinary bladder. Environ. Mol. Mutagen. 2009. Published 2009 by Wiley-Liss, Inc. [source] Effects of ecdysteroids on Chlorella vulgarisPHYSIOLOGIA PLANTARUM, Issue 3 2004Andrzej Bajguz The effects of three ecdysteroids, 20-hydroxyecdysone (20E), 2-deoxy-20-hydroxyecdysone (2d20E) and 20-hydroxyecdysone 22-acetate (20E22Ac), on growth and the levels of cellular components in Chlorella vulgaris Beijerinck (Trebouxiophyceae) are reported and compared with data previously reported for ecdysone (E; Bajguz A and Koronka A, Plant Physiol Biochem 39: 707,715, 2001). All three 20-hydroxyecdysteroids stimulate growth of C. vulgaris cells over a wide concentration range (10,16 to 10,7 M). Optimal stimulation is observed at 10,9 M with each ecdysteroid. High concentrations (>10,6 M) are cytotoxic. The potency ranking of the ecdysteroids is 20E > 20E22Ac > 2d20E > E. Levels per cell of DNA, RNA, protein, sugars, organic and inorganic phosphorus, chlorophylls a and b and phaeophytins a and b are all stimulated by ecdysteroid treatment when compared with the untreated control cells. Possible modes of action of ecdysteroids on C. vulgaris cells are discussed. [source] Customized mandibular orthotics in the prevention of concussion/mild traumatic brain injury in football players: a preliminary studyDENTAL TRAUMATOLOGY, Issue 5 2009G. Dave Singh However, previous investigations have primarily studied non-customized mouthguards without dental/temporo-mandibular joint examinations of the subjects. Therefore, the aim of this study is to determine whether the use of a customized mandibular orthotic after temporo-mandibular joint assessment reduces the incidence of concussion/mild traumatic brain injuries in high-school football players. Materials and methods:, Using a longitudinal, retrospective design, data were collected from a cohort of football players (n = 28) over three seasons using a questionnaire. The mean age of the sample prior to the use of the customized mandibular orthotic was 17.3 years ± 1.9. Prior to deployment, dental records and temporo-mandibular joint evaluations were undertaken, as well as neurocognitive assessment, including history of concussion/mild traumatic brain injuries. After establishing optimal jaw position, a customized mandibular orthotic was fabricated to the new spatial relations. Results:, The mean age of the sample after three seasons was 19.7 years ± 2.0. Prior to the use of the customized mandibular orthotic, the mean self-reported incidence of concussion/mild traumatic brain injuries was 2.1 ± 1.4 concussive events. After the deployment of the customized mandibular orthotic the number of concussive events fell to 0.11 ± 0.3 with an odds ratio of 38.33 (95% CI 8.2,178.6), P < 0.05. Conclusion:, The preliminary results of this study suggest that a customized mandibular orthotic may decrease the incidence of concussion/mild traumatic brain injuries in high- school football athletes, but a comprehensive study is required to confirm these initial findings. Furthermore, additional research is necessary to indicate the possible mode(s) of action of a customized mandibular orthotic in the prevention of concussion/mild traumatic brain injuries. [source] Metagenome and mRNA expression analyses of anaerobic methanotrophic archaea of the ANME-1 groupENVIRONMENTAL MICROBIOLOGY, Issue 2 2010Anke Meyerdierks Summary Microbial consortia mediating the anaerobic oxidation of methane with sulfate are composed of methanotrophic Archaea (ANME) and Bacteria related to sulfate-reducing Deltaproteobacteria. Cultured representatives are not available for any of the three ANME clades. Therefore, a metagenomic approach was applied to assess the genetic potential of ANME-1 archaea. In total, 3.4 Mbp sequence information was generated based on metagenomic fosmid libraries constructed directly from a methanotrophic microbial mat in the Black Sea. These sequence data represent, in 30 contigs, about 82,90% of a composite ANME-1 genome. The dataset supports the hypothesis of a reversal of the methanogenesis pathway. Indications for an assimilatory, but not for a dissimilatory sulfate reduction pathway in ANME-1, were found. Draft genome and expression analyses are consistent with acetate and formate as putative electron shuttles. Moreover, the dataset points towards downstream electron-accepting redox components different from the ones known from methanogenic archaea. Whereas catalytic subunits of [NiFe]-hydrogenases are lacking in the dataset, genes for an [FeFe]-hydrogenase homologue were identified, not yet described to be present in methanogenic archaea. Clustered genes annotated as secreted multiheme c -type cytochromes were identified, which have not yet been correlated with methanogenesis-related steps. The genes were shown to be expressed, suggesting direct electron transfer as an additional possible mode to shuttle electrons from ANME-1 to the bacterial sulfate-reducing partner. [source] Molecular docking studies of selected tricyclic and quinone derivatives on trypanothione reductase of Leishmania infantumJOURNAL OF COMPUTATIONAL CHEMISTRY, Issue 13 2010Santhosh Kannan Venkatesan Abstract Visceral leishmaniasis, most lethal form of Leishmaniasis, is caused by Leishmania infantum in the Old world. Current therapeutics for the disease is associated with a risk of high toxicity and development of drug resistant strains. Thiol-redox metabolism involving trypanothione and trypanothione reductase, key for survival of Leishmania, is a validated target for rational drug design. Recently published structure of trypanothione reductase (TryR) from L. infantum, in oxidized and reduced form along with Sb(III), provides vital clues on active site of the enzyme. In continuation with our attempts to identify potent inhibitors of TryR, we have modeled binding modes of selected tricyclic compounds and quinone derivatives, using AutoDock4. Here, we report a unique binding mode for quinone derivatives and 9-aminoacridine derivatives, at the FAD binding domain. A conserved hydrogen bonding pattern was observed in all these compounds with residues Thr335, Lys60, His461. With the fact that these residues aid in the orientation of FAD towards the active site forming the core of the FAD binding domain, designing selective and potent compounds that could replace FAD in vivo during the synthesis of Trypanothione reductase can be deployed as an effective strategy in designing new drugs towards Leishmaniasis. We also report the binding of Phenothiazine and 9-aminoacridine derivatives at the Z site of the protein. The biological significance and possible mode of inhibition by quinone derivatives, which binds to FAD binding domain, along with other compounds are discussed. © 2010 Wiley Periodicals, Inc. J Comput Chem, 2010 [source] Studies on the molecular recognition between bioactive peptides and angiotensin-converting enzymeJOURNAL OF MOLECULAR RECOGNITION, Issue 2 2009A.S. Pina Abstract High blood pressure or hypertension is a condition affecting many individuals and represents a controllable risk factor for cardiovascular diseases such as coronary heart disease and stroke. A non-pharmacological approach to manage these includes the application of food components with antihypertensive activity. Milk protein-derived peptides have been exploited as natural hypotensive agents, namely the peptides Val-Pro-Pro (VPP) and Ile-Pro-Pro (IPP), already commercialized in functional foods as a potential alternative to synthetic drugs. These bioactive peptides inhibit in vitro and in vivo the Angiotensin I-converting enzyme (ACE), a protein with an important role in blood pressure regulation. In this work, we attempted to elucidate the possible mode of interaction between the peptides and ACE, including mechanisms of binding to the cofactor Zn2+, and further contrast this with the known mode of inhibition exerted by synthetic drugs (Captopril, Enalaprilat and Lisinopril). The bioactive peptide Ala-Leu-Pro-Met-His-Ile-Arg (ALPMHIR), also known to inhibit the enzyme ACE but with a lower efficiency than VPP and IPP, was utilized in the docking studies for comparison. It was observed that the best docking poses obtained for VPP and IPP were located at the ACE catalytic site with very high resemblance to the drugs mode of interaction, including the coordination with Zn2+. As for ALPMHIR, the best docking poses were located in the narrow ACE channel outside the catalytic site, representing higher affinity energies and fewer resemblances with the interaction established by drugs. Copyright © 2008 John Wiley & Sons, Ltd. [source] The mode of action of venom from the endoparasitic wasp Pimpla hypochondriaca (Hymenoptera: Ichneumonidae) involves Ca+2 -dependent cell death pathways,ARCHIVES OF INSECT BIOCHEMISTRY AND PHYSIOLOGY (ELECTRONIC), Issue 3 2009David B. Rivers Abstract The endoparasitoid Pimpla hypochondriaca injects venom during oviposition to condition its lepidopteran hosts. Venom is a complex mixture of proteins and polypeptides, many of which have been identified as enzymes, including phenoloxidase, endopeptidase, aminopeptidase, hydrolase, and angiotensin-converting enzyme. Constituents of the venom have been shown to possess cytolytic and paralytic activity, but the modes of action of factor(s) responsible for exerting such effects have not been deciphered. In this study, we examined the mode of action of isolated venom using cultured cells (BTI-TN-5B1-4). A series of blockage and inhibition assays were performed using a potent inhibitor (phenylthiourea, PTU) of venom phenoloxidase, and anti-calreticulin antibodies. Monolayers exposed to venom alone were highly susceptible with more than 84.6±2.3% dead within 15,min. Susceptible cells displayed a retraction of cytoplasmic extensions, rounding, and swelling prior to lysis in more than half (55.7±1.7%) of the dying cells. Within 15,min of exposure to venom, cells displayed qualitative increases in [Ca+2]i as evidenced by staining with the calcium-sensitive probe fluo-4 AM, and mitochondrial membrane potential (,,m) was undetectable by 5,min post-treatment with venom. These venom-mediated changes occurred regardless of whether an external source of calcium was present, or whether venom was pre-treated with PTU. In contrast, venom toxicity was attenuated by treatment with anti-calreticulin antibodies. Not only did fewer cells die when exposed to antibody-treated venom but also cell swelling diminished and no increases in intracellular calcium were detected. A possible mode of action for the venom is discussed. © 2009 Wiley Periodicals, Inc. [source] In vivo and in vitro activity of venom from the endoparasitic wasp Pimpla turionellae (L.) (Hymenoptera: Ichneumonidae)ARCHIVES OF INSECT BIOCHEMISTRY AND PHYSIOLOGY (ELECTRONIC), Issue 2 2006Ekrem Ergin Abstract The biological activity of venom from Pimpla turionellae L. (Hymenoptera: Ichneumonidae) was examined in vivo toward larvae and pupae of Galleriae mellonella L. (Lepidoptera: Pyralidae), and in vitro toward bacterial and fungal cultures, as well as cultured insect cells. Pupae of G. mellonella were far more susceptible to the venom than larvae. At low doses of venom [0.1 venom reservoir equivalents (VRE)], pupal abdominal mobility was inhibited within 30 min, and by 24 h, all pupae injected with venom concentrations >0.5 VRE were completely paralyzed. These same doses of venom resulted in an inhibition of adult emergence. Host larvae were far less sensitive to wasp venom as evidenced by all venom injected larvae remaining responsive to mechanical stimulation by 1 h post injection, even at concentrations equivalent to 1 venom reservoir. Eventually (>2 h at 25°C), venom-injected larvae became immobile, then flaccid, and all died within 24 h post-injection. At lower concentrations of wasp venom, the onset of paralysis was delayed by comparison to that evoked by 1 VRE, and few host larvae were able to pupate. Development of host larvae to adult emergence was also reduced in a dose-dependent manner, with eclosion completely prevented at high concentrations (>0.5 VRE) of venom. Venom doses <0.5 VRE did not appear to induce paralysis or alter larval development. When venom was incubated with bacterial or fungal cultures, no antimicrobial activity was detected. However, wasp venom was found to be cytotoxic and cytolytic to cultured cells derived from the cabbage looper Trichoplusia ni Hubner (Lepidoptera: Noctuidae) and the yellow fever mosquito, Aedes aegypti (L.) (Diptera: Culcidae). Though both cell types displayed similar susceptibility in terms of LC50s, the lepidopteran cells responded much more rapidly with regard to the onset of morphological changes and the timing of cell death. A possible mode of action for the venom is discussed. Arch. Insect Biochem. Physiol. 61:87,97, 2006. © 2006 Wiley-Liss, Inc. [source] Axillary vein perforation by the medial cutaneous nerve of the forearmCLINICAL ANATOMY, Issue 4 2004T.S. Roy Abstract Variation in the venous pattern in the arm is common. In this study, a rare variant of the axillary vein and its association with the median cutaneous nerve of the forearm is described. In the axilla, the medial cutaneous nerve of the forearm penetrated the axillary vein, thereby creating two narrow venous channels at the site of passage. Such variations are important because a large number of diagnostic and therapeutic invasive procedures are carried out on veins. A possible mode of origin and the clinical importance of this variation are discussed. Clin. Anat. 17:300,302, 2004. © 2004 Wiley-Liss, Inc. [source] Predictive tracking over occlusions by 4-month-old infantsDEVELOPMENTAL SCIENCE, Issue 5 2007Claes Von Hofsten Two experiments investigated how 16,20-week-old infants visually tracked an object that oscillated on a horizontal trajectory with a centrally placed occluder. To determine the principles underlying infants' tendency to shift gaze to the exiting side before the object arrives, occluder width, oscillation frequency, and motion amplitude were manipulated resulting in occlusion durations between 0.20 and 1.66 s. Through these manipulations, we were able to distinguish between several possible modes of behavior underlying ,predictive' actions at occluders. Four such modes were tested. First, if passage-of-time determines when saccades are made, the tendency to shift gaze over the occluder is expected to be a function of time since disappearance. Second, if visual salience of the exiting occluder edge determines when saccades are made, occluder width would determine the pre-reappearance gaze shifts but not oscillation frequency, amplitude, or velocity. Third, if memory of the duration of the previous occlusion determines when the subjects shift gaze over the occluder, it is expected that the gaze will shift after the same latency at the next occlusion irrespective of whether occlusion duration is changed or not. Finally, if infants base their pre-reapperance gaze shifts on their ability to represent object motion (cognitive mode), it is expected that the latency of the gaze shifts over the occluder is scaled to occlusion duration. Eye and head movements as well as object motion were measured at 240 Hz. In 49% of the passages, the infants shifted gaze to the opposite side of the occluder before the object arrived there. The tendency to make such gaze shifts could not be explained by the passage of time since disappearance. Neither could it be fully explained in terms of visual information present during occlusion, i.e. occluder width. On the contrary, it was found that the latency of the pre-reappearance gaze shifts was determined by the time of object reappearance and that it was a function of all three factors manipulated. The results suggest that object velocity is represented during occlusion and that infants track the object behind the occluder in their ,mind's eye'. [source] Prediction of success and failure of behavior modification as treatment for dental anxietyEUROPEAN JOURNAL OF ORAL SCIENCES, Issue 4 2004I. Eli Behavior modification techniques are effective in the treatment of extreme dental anxiety, but their success is by no means absolute. In the present article, the Corah Dental Anxiety Scale (DAS), the self-report symptom inventory SCL-90R and a questionnaire accessing subjects' daydreaming styles (the Short Imaginal Process Inventory) were used to develop possible predictive measures for success and failure of behavior modification as a treatment for dental fear. The patients' level of distractibility and mind wandering, initial dental anxiety and somatization significantly predicted the success of therapy. The odds ratio indicated that the risk of therapy failure increased about 11 times with an increase of one scale of the Poor Attention Control Scale, about three times with an increase of one level of the mean DAS score, and 0.17 times with an increase of one level of somatization. The predictive value of the chosen scales was 80%. Thus, the use of these scales as part of an initial admittance process for patients who suffer from dental anxiety can enhance our ability to better recognize patients who are prone to fail behavior therapy as treatment for their problem, and enable their referral for other possible modes of treatment. [source] Arginine-induced conformational change in the c -ring/a -subunit interface of ATP synthaseFEBS JOURNAL, Issue 9 2008Thomas Vorburger The rotational mechanism of ATP synthases requires a unique interface between the stator a subunit and the rotating c -ring to accommodate stability and smooth rotation simultaneously. The recently published c -ring crystal structure of the ATP synthase of Ilyobacter tartaricus represents the conformation in the absence of subunit a. However, in order to understand the dynamic structural processes during ion translocation, studies in the presence of subunit a are required. Here, by intersubunit Cys,Cys cross-linking, the relative topography of the interacting helical faces of subunits a and c from the I. tartaricus ATP synthase has been mapped. According to these data, the essential stator arginine (aR226) is located between the c -ring binding pocket and the cytoplasm. Furthermore, the spatially vicinal residues cT67C and cG68C in the isolated c -ring structure yielded largely asymmetric cross-linking products with aN230C of subunit a, suggesting a small, but significant conformational change of binding-site residues upon contact with subunit a. The conformational change was dependent on the positive charge of the stator arginine or the aR226H substitution. Energy-minimization calculations revealed possible modes for the interaction between the stator arginine and the c -ring. These biochemical results and structural restraints support a model in which the stator arginine operates as a pendulum, moving in and out of the binding pocket as the c -ring rotates along the interface with subunit a. This mechanism allows efficient interaction between subunit a and the c- ring and simultaneously allows almost frictionless movement against each other. [source] Prolonging microbial shelf life of foods through the use of natural compounds and non-thermal approaches , a reviewINTERNATIONAL JOURNAL OF FOOD SCIENCE & TECHNOLOGY, Issue 2 2009Maria Rosaria Corbo Summary This paper proposes a review of some alternative approaches for food stabilisation and shelf life prolonging (based on the use of natural compounds and/or non-thermal techniques). After a brief description of food structure implication on the way of using the alternative approaches, two paragraphs summarise the topics of natural molecules (essential oils, lysozyme, lactoferrin and lactoperoxidase system, fatty acids, chitosan) and non-thermal approaches (high hydrostatic and homogenisation pressures, pulsed electric fields, high power ultrasound and irradiation). Finally, the last sections deal with the use of combined hurdles (along with the proposal of three possible modes of action of a multi-target preservation), the mathematical approaches for shelf life evaluating and some critical issues to be addressed in the future for a real scaling up of the proposed techniques. [source] A random evolution related to a Fisher,Wright,Moran model with mutation, recombination and driftMATHEMATICAL METHODS IN THE APPLIED SCIENCES, Issue 18 2003Adam Bobrowski Abstract The paper deals with a model of the genetic process of recombination, one of the basis mechanisms of generating genetic variability. Mathematically, the model can be represented by the so-called random evolution of Griego and Hersch, in which a random switching process selects from among several possible modes of operation of a dynamical system. The model, introduced by Polanska and Kimmel, involves mutations in the form of a time-continuous Markov chain and genetic drift. We demonstrate asymptotic properties of the model under different demographic scenarios for the population in which the process evolves. Copyright © 2003 John Wiley & Sons, Ltd. [source] Guided modes in a grounded slab waveguide of uniaxially anisotropic left-handed materialMICROWAVE AND OPTICAL TECHNOLOGY LETTERS, Issue 7 2007Songhua Liu Abstract The guidance conditions of TE and TM waves with both real and imaginary transverse wave numbers in a grounded slab waveguide of uniaxially anisotropic left-handed material are derived. The mode properties for guided TE waves, such as the existence of guided modes, the number of possible modes and the mode cutoffs are analyzed in different cases graphically. Furthermore, we come into some new conclusions different from the mode properties in an isotropic LHM slab. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 1644,1648, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.22531 [source] Malnutrition-Associated Rash of Cystic FibrosisPEDIATRIC DERMATOLOGY, Issue 5 2000Gary L. Darmstadt M.D. We measured essential fatty acid (EFA) levels in the serum of a 4-month-old girl with an erythematous, desquamating, periorificially accentuated rash in association with malnutrition and her 2-year-old sister who was diagnosed concurrently with CF but had no rash or signs of malnutrition. Both patients had biochemical evidence of EFA deficiency, suggesting that development of the rash is multifactorial. Clinical presentation, management, and possible modes of pathogenesis of the rash are reviewed. Pathogenesis of the rash appears to involve a complex interaction among deficiencies of EFAs, zinc, protein, and possibly copper, leading to disordered prostaglandin metabolism or cytokine production, or free radical-induced damage to cellular membranes due to a lack of nutrient-derived protective antioxidants. [source] Claudin-5a in developing zebrafish brain barriers: another brick in the wallBIOESSAYS, Issue 9 2010Salim Abdelilah-Seyfried Abstract Claudins serve essential roles in regulating paracellular permeability properties within occluding junctions. Recent studies have begun to elucidate developmental roles of claudins within immature tissues. This work has uncovered an involvement of several claudins in determining tight junction properties that have an effect on embryonic morphogenesis and physiology. During zebrafish brain morphogenesis, Claudin-5a determines the paracellular permeability of tight junctions within a transient neuroepithelial-ventricular barrier that maintains the hydrostatic fluid pressure required for brain ventricular lumen expansion. However, the roles of Claudins in development may well extend beyond being mere junctional components. Several post-translational modifications of Claudins have been characterized that indicate a direct regulation by developmental signals. This review focuses on the involvement of Claudin-5a in cerebral barrier formation in the zebrafish embryo and includes some speculations about possible modes of regulation. [source] Interspecific Competition and Niche Separation in Primates: A Global AnalysisBIOTROPICA, Issue 3 2009Brian M. Schreier ABSTRACT Primates are an extraordinarily well-known tropical forest, mammalian taxon. We investigated potential modes of niche separation in primates by identifying sympatric species with putatively similar niche characteristics and assessing potential competition using data gleaned from an extensive literature review. We defined competing species-pairs as (a) sympatric species in which (b) the body mass of the larger species was within 30 percent of the smaller species' mass and (c) the species had the same category of diet. A sample of 43 well-studied forests (7,20 per continent) provided 673 pairs of sympatric primate species. Of these, 45 pairs (7%) are potential competitors by our definition. Africa has the largest number of competing pairs (17 pairs), while Asia might have the highest percentage of competitors in each forest site (17%). Niche separation was investigated for each pair by examining them for each of eight possible modes of separation: detailed differences in diets (28% of potential competitors), use of different heights in the forest (25%), use of different types of forest (14%), use of different locations within the forest (11%), use of support branches of different diameters (7%), different ranging behavior (6%), different techniques of prey capture (4%), and differential timing of activity (4%). The use of different heights in the forest is the dominant form of potential separation in Africa (31% of competing species-pairs) and Asia (38%), while detailed differences in diet appears to be the primary mode of niche separation in the Americas (26%) and Madagascar (32%). [source] | |||||||||||||||||||