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A common challenge that oviparous animals face is securing survivorship during the vulnerable embryonic stage. One of the parental investment strategies to improve survivorship is providing physical structures to protect the embryos. In amphibians, there is a notable diversity in jelly-layer structures surrounding eggs. Previous studies show that these jelly layers provide eggs with protection against egg predators, egg pathogens, and desiccation. However, few studies examined the cost-benefit relationship of the jelly-layer structures. By using the predator-prey interaction between wood frog (Lithobates sylvaticus) tadpoles and spotted salamander (Ambystoma maculatum) eggs as a model system, we tested three hypotheses: (1) having the outer jelly layers would be costly to the embryos, (2) the relative benefit of the structural egg defense would become apparent and increase as the intensity of egg predation increases, and (3) a certain degree of predation would increase the hatching success of salamander embryos by mechanically thinning the thick outer jelly layers and increasing oxygen diffusion throughout an egg mass. To test these hypotheses, we conducted a factorial experiment in which we crossed four egg-predation levels with two jelly-layer conditions, intact or removed. We found that the jelly layers were essential in protecting spotted salamander embryos from wood frog tadpoles but that the associated cost was apparent in no-predation treatments. The differential survivorship between intact eggs and eggs without jelly layers showed that the fitness advantage of jelly layers increased as the level of predation increased. Finally, the hatching success of intact egg masses was highest under the high predation conditions. These results imply that the evolution of the jelly-layer thickness occurred under constant egg-predation pressure. Given this predator-prey coevolution, egg predators may play a critical role in improving the hatching success of salamander embryos under certain conditions.
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Road deicing salts are frequently used in northern regions of the world during the winter and early spring months. As a result, a significant portion of road runoff into surrounding aquatic habitats contains road deicing salts. Previous studies found road salt contaminations in vernal pools that pond-breeding amphibians commonly use, including spotted salamanders (Ambystoma maculatum) and wood frogs (Lithobates sylvaticus). Studies have examined the impact of road salt on both amphibian species, but to our knowledge no previous studies have examined how road salt impacts the interspecific competition between both amphibians. We hypothesized that road salt would negatively impact growth and survivorship of both amphibian species. During the spring and summer of 2017, we conducted an outdoor mesocosm experiment in which we created eight experimental conditions with three main factors: presence/absence of NaCl (1000 mg/L Cl-), presence/absence of interspecific competition between the two amphibian species (A. maculatum and L. sylvaticus), and presence/absence of predatory dragonfly larvae (Family Libellulidae). Our experiment revealed that salt delayed hatching and increased deformity in spotted salamander hatchlings. Additionally, salt reduced salamander survivorship by 62% and frog survivorship by 30%. Wood frog tadpoles and road salt interacted to diminish salamander survivorship a further 80% beyond salt alone, likely through an increase in interspecific competition. Road salt increased the larval period of salamanders and decreased the proportion metamorphosed by the end of the experiment. Dragonfly larvae reduced salamander survivorship by 35%, whereas they increased wood frog tadpole development rates. Dragonfly larvae and salt interacted to alter tadpole denticle size, with salt negating the impact of dragonfly larvae. Thus, we found that salt interfered with aquatic predatory chemical cues. Overall, the results of this study suggest that management strategies should be implemented in order to reduce the impact of road salts on freshwater aquatic ecosystems.
Asunto(s)
Ambystoma , Odonata , Animales , Cloruro de Sodio/farmacología , Conducta Predatoria , Ecosistema , Sales (Química) , Ranidae , Larva , UrodelosRESUMEN
Understanding the impact of geological events on diversification processes is central to evolutionary ecology. The recent amalgamation between ecological niche models (ENMs) and phylogenetic analyses has been used to estimate historical ranges of modern lineages by projecting current ecological niches of organisms onto paleoclimatic reconstructions. A critical assumption underlying this approach is that niches are stable over time. Using Notophthalmus viridescens (eastern newt), in which four ecologically diverged subspecies are recognized, we introduce an analytical framework free from the niche stability assumption to examine how refugial retreat and subsequent postglacial expansion have affected intraspecific ecological divergence. We found that the current subspecies designation was not congruent with the phylogenetic lineages. Thus, we examined ecological niche overlap between the refugial and modern populations, in both subspecies and lineage, by creating ENMs independently for modern and estimated last glacial maximum (LGM) newt populations, extracting bioclimate variables by randomly generated points, and conducting principal component analyses. Our analyses consistently showed that when tested as a hypothesis, rather than used as an assumption, the niches of N. viridescens lineages have been unstable since the LGM (both subspecies and lineages). There was greater ecological niche differentiation among the subspecies than the modern phylogenetic lineages, suggesting that the subspecies, rather than the phylogenetic lineages, is the unit of the current ecological divergence. The present study found little evidence that the LGM refugial retreat caused the currently observed ecological divergence and suggests that ecological divergence has occurred during postglacial expansion to the current distribution ranges.
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Ecología , Ecosistema , Filogenia , Salamandridae/clasificación , Salamandridae/fisiología , Animales , Historia Antigua , Cubierta de Hielo , Modelos Biológicos , Filogeografía , Análisis de Componente Principal , Salamandridae/genética , Análisis de Secuencia de ADNRESUMEN
The lack of effective tools has hampered out ability to assess the size, growth and ages of clonal plants. With Serenoa repens (saw palmetto) as a model, we introduce a novel analytical framework that integrates DNA fingerprinting and mathematical modelling to simulate growth and estimate ages of clonal plants. We also demonstrate the application of such life-history information of clonal plants to provide insight into management plans. Serenoa is an ecologically important foundation species in many Southeastern United States ecosystems; yet, many land managers consider Serenoa a troublesome invasive plant. Accordingly, management plans have been developed to reduce or eliminate Serenoa with little understanding of its life history. Using Amplified Fragment Length Polymorphisms, we genotyped 263 Serenoa and 134 Sabal etonia (a sympatric non-clonal palmetto) samples collected from a 20 × 20 m study plot in Florida scrub. Sabal samples were used to assign small field-unidentifiable palmettos to Serenoa or Sabal and also as a negative control for clone detection. We then mathematically modelled clonal networks to estimate genet ages. Our results suggest that Serenoa predominantly propagate via vegetative sprouts and 10,000-year-old genets may be common, while showing no evidence of clone formation by Sabal. The results of this and our previous studies suggest that: (i) Serenoa has been part of scrub associations for thousands of years, (ii) Serenoa invasion are unlikely and (ii) once Serenoa is eliminated from local communities, its restoration will be difficult. Reevaluation of the current management tools and plans is an urgent task.
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Conservación de los Recursos Naturales/métodos , Dermatoglifia del ADN/métodos , Longevidad/fisiología , Reproducción Asexuada/fisiología , Serenoa/fisiología , Análisis del Polimorfismo de Longitud de Fragmentos Amplificados , Florida , Modelos Genéticos , Serenoa/genética , Especificidad de la EspecieRESUMEN
Polyphenism, which allows a single genotype to express multiple discrete phenotypes in response to environmental cues, is an adaptive trait in heterogeneous environments. Pond hydroperiod is an important ecological parameter affecting amphibian life history, and variation in local pond hydrology has been hypothesized to play a role in species divergence via changes in polyphenism. The eastern newt (Notophthalmus viridescens) expresses life cycle polyphenism. Larvae develop along three possible pathways: metamorphosis to aquatic lunged adult via a terrestrial juvenile (eft) stage, metamorphosis directly to an aquatic lunged adult, or maturation directly to an aquatic gilled adult without metamorphosis (i.e., paedomorphosis). Subspecies of N. viridescens vary in their polyphenic patterns, suggesting possible adaptation to different environments. However, no studies have experimentally tested how genetic and environmental components contribute to the observed differences among subspecies and whether such differences may facilitate divergence. We tested whether adaptation to local pond hydrology via polyphenic changes existed among subspecies by rearing larvae of three subspecies (N. v. dorsalis, N. v. louisianensis, and N. v. viridescens) along three hydroperiod regimes (short, long, and constant) in outdoor artificial ponds. We found that larval N. v. viridescens obligately metamorphosed to efts under all hydroperiods, whereas N. v. dorsalis and N. v. louisianensis exhibited plasticity: larvae metamorphosed to efts under drying conditions but metamorphosed directly to aquatic adults or became paedomorphic in constant water. Also, N. v. viridescens metamorphosed to efts faster and at a smaller body size than the other two subspecies. These data suggest that subspecies of N. viridescens are adapted to different pond hydroperiods, supporting the potential for polyphenism to facilitate divergence. Canalizing selection for certain alternative phenotypes within a single species in which other populations remain plastic may play an important role in the initiation of ecological divergence.
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Adaptación Biológica , Metamorfosis Biológica , Notophthalmus viridescens/crecimiento & desarrollo , Fenotipo , Humedales , Animales , Femenino , Masculino , Notophthalmus viridescens/genéticaRESUMEN
PURPOSE: To investigate the relationship between morphological changes of the optic nerve head (ONH) and macular sensitivity(MS) determined with blue-on-yellow(B on Y) and white on white (W on W) perimetry in normal subjects and patients with glaucoma. METHODS: One randomly chosen eye was evaluated in each of 28 normal subjects, 23 patients with ocular hypertension(OH), and 23 patients with early primary open-angle glaucoma(POAG). Mean values for MS by B on Y and W on W perimetry were obtained with the macular program using a modified Humphrey Field Analyzer(HFA). The Heidelberg Retina Tomograph(HRT) with software version 2.01 was used to evaluate the topographic parameters of temporal sector in ONH. RESULTS: There was no significant difference in temporal topographic parameters of ONH among the three clinical groups. Mean values for MS of B on Y and W on W perimetry in early POAG were significantly lower than in normal subjects and OH. Mean values for MS of W on W perimetry showed no significant correlation with ONH parameters of the temporal sector. In early POAG, mean values for MS of B on Y perimetry significantly correlated with cup area, cup/disc area ratio, cup volume, and rim volume in the temporal sector of ONH. CONCLUSION: The measurement of mean MS of B on Y might be able to detect the glaucomatous optic nerve damage due to increased intraocular pressure prior to the morphological changes of ONH in early stages of glaucoma.
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Glaucoma de Ángulo Abierto/fisiopatología , Mácula Lútea/fisiopatología , Disco Óptico/patología , Pruebas del Campo Visual , Proteínas del Ojo , Glaucoma de Ángulo Abierto/diagnóstico , Humanos , Persona de Mediana Edad , Hipertensión Ocular/fisiopatología , Opsinas de BastonesRESUMEN
Purpose: The effect of topical 2% carteolol hydrochloride on the ocular blood flow dynamics in normal human eyes was studied.Materials and Methods: Ten healthy volunteers were studied using color Doppler imaging and scanning laser Doppler flowmetry. In the first experiments, one eye received 30 µl of 2% carteolol hydrochloride twice daily for 7 days and the fellow eye a placebo in a randomized masked manner. The blood flow velocity of the central retinal artery, the ophthalmic artery, and the short posterior ciliary artery, the blood flow volume of the peripapillary retina (PPR), intraocular pressure (IOP), ocular perfusion pressure (OPP) and pulse rate (PR) were measured before treatment, 2 hours after the initial instillation, and after the last instillation on the 7th day. In the control experiments, 30 µl of placebo was instilled in both eyes, and the above parameters were measured according to the same time schedule as in the first experiments.Results: In the carteolol-treated eyes, the systolic maximum (p = 0.012) and diastolic minimum (p = 0.019) blood flow velocities of the ophthalmic artery, and the blood flow volume of the superior (p = 0.003), central (p = 0.001) and inferior (p = 0.000) PPR showed significant increases in the first experiments compared with the control experiments. IOP and OPP in both eyes showed significant reduction in the first experiments compared with the control study.Conclusion: These results indicated that topical carteolol hydrochroride increases the blood flow of the intraorbital microcirculation and PPR.
RESUMEN
Purpose: A young patient of ophthalmoplegic migraine with recurrent oculomotor nerve palsy is reported.Case: A 4-year-old girl came to our hospital complaining of recurrent left ptosis and double vision which completely resolved within a few days. She had a history of drowsiness after vomiting every two months. Left oculomotor nerve palsy with internal ophthalmoplegia was observed. Electroencephalography revealed mild changes, but computed tomography, single photon emission computed tomography, and cerebrovascular Doppler-ultrasound examination demonstrated no abnormalities. This oculomotor nerve palsy completely improved on the next day.Results: Thereafter, left episodic mydriasis and oculomotor nerve palsy occurred twice each. However, the frequency and symptoms of migraine were remarkably reduced by topical administration of 0.25% timolol maleate twice daily to both eyes.Conclusion: In isolated oculomotor nerve palsy in childhood, ophthalmoplegic migraine should be also considered. We emphasize that a detailed case history is very important to its diagnosis.
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PURPOSE: The effect of topical 2% calteolol hydrochloride on the ocular blood flow dynamics in normal human eyes was studied. MATERIALS AND METHODS: Ten healthy volunteers were studied using color Doppler imaging and scanning laser Doppler flowmetry. In the first experiments, one eye received 30 microliters of 2% carteolol hydrochloride twice daily for 7 days and the fellow eye a placebo in a randomized masked manner. The blood flow velocity of the central retinal artery, the ophthalmic artery, and the short posterior ciliary artery, the blood flow volume of the peripapillary retina (PPR), intraocular pressure (IOP), ocular perfusion pressure (OPP) and pulse rate (PR) were measured before treatment, 2 hours after the initial instillation, and after the last instillation on the 7th day. In the control experiments, 30 microliters of placebo was instillated in both eyes, and the above parameters were measured according to the same time schedule as in the first experiments. RESULTS: In the carteolol-treated eyes, the systolic maximum (p = 0.012) and diastolic minimum (p = 0.019) blood flow velocities of the ophthalmic artery, and the blood flow volume of the superior (p = 0.003), central (p = 0.001) and inferior (p = 0.000) PPR showed significant increases in the first experiments compared with the control experiments. IOP and OPP in both eyes showed significant reduction in the first experiments compared with the control study. CONCLUSION: These results indicated that topical carteolol hydrochroride increases the blood flow of the intraorbital microcirculation and PPR.
Asunto(s)
Antagonistas Adrenérgicos beta/farmacología , Carteolol/farmacología , Ojo/irrigación sanguínea , Simpaticolíticos/farmacología , Adulto , Femenino , Hemodinámica/efectos de los fármacos , Humanos , Flujometría por Láser-Doppler , Masculino , Microcirculación/efectos de los fármacos , Persona de Mediana Edad , Nervio Óptico/irrigación sanguínea , Flujo Sanguíneo Regional/efectos de los fármacosRESUMEN
PURPOSE: A young patient of ophthalmoplegic migraine with recurrent oculomotor nerve palsy is reported. CASE: A 4-year-old girl came to our hospital complaining of recurrent left ptosis and double vision which completely resolved within a few days. She had a history of drowsiness after vomiting every two months. Left oculomotor nerve palsy with internal ophthalmoplegia was observed. Electroencephalography revealed mild changes, but computed tomography, single photon emission computed tomography, and cerebrovascular Doppler-ultrasound examination demonstrated no abnormalities. This oculomotor nerve palsy completely improved on the next day. RESULTS: Thereafter, left episodic mydriasis and oculomotor nerve palsy occurred twice each. However, the frequency and symptoms of migraine were remarkably reduced by topical administration of 0.25% timolol maleate twice daily to both eyes. CONCLUSION: In isolated oculomotor nerve palsy in childhood, ophthalmoplegic migraine should be also considered. We emphasize that a detailed case history is very important to its diagnosis.
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Trastornos Migrañosos/complicaciones , Oftalmoplejía/complicaciones , Preescolar , Femenino , Humanos , RecurrenciaRESUMEN
An abietane-type diterpene, named vitetrifolin A, and two labdane-type diterpenes, named vitetrifolins B and C, were isolated from the acetone extract of the fruits of Vitex trifolia L. (Viticis Fructus; Verbenaceae) along with three known diterpenes, rotundifuran, dihydrosolidagenone and abietatriene 3beta-ol. The structures of these compounds were elucidated on the basis of spectroscopic analysis, X-ray crystallographic analysis and chemical evidence.
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Diterpenos/aislamiento & purificación , Plantas Medicinales , Vitex/química , Cristalografía por Rayos X , Diterpenos/química , Frutas/química , Conformación MolecularRESUMEN
The phagocyte NADPH oxidase is activated during phagocytosis to produce superoxide, a precursor of microbicidal oxidants. The formation of the active oxidase complex at the membrane requires translocation of the Rac GTPase and two specialized cytosolic proteins that harbor SH3 domains, p67phox and p47phox. Another SH3-domain-containing protein p40phox, which is constitutively associated with p67phox in phagocytes, also enters the complex upon cell stimulation. Here we describe how we cloned mouse cDNAs encoding p40phox and its partner in phagocytes, p67phox. Both p40phox and p67phox comprise several protein-binding modules that are structurally and functionally well conserved between mouse and human, indicating their nature as adaptor proteins. We have also systematically investigated expression of the gene for p40phox in comparison with those for p67phox and p47phox. Distributions of the mRNAs for the three proteins among tissues are similar, with the most abundant expression in the spleen. The messages are abundant not only in phagocytic cells, but also in B cell lineage. The p40phox gene, but not the other two, is expressed in some types of cells such as plasma cells and T lymphocytes. Furthermore, in situ hybridization analysis shows that the p40phox mRNA is distributed in neuronal cells of mouse brain, providing evidence that one of the genes for the specialized oxidase factors is expressed in neurons. These observations raise the possibility that the adaptor protein p40phox plays a heretofore unsuspected role via interacting with other proteins in the cells that do not express p67phox or p47phox.
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NADPH Oxidasas/biosíntesis , NADPH Oxidasas/química , Fagocitos/enzimología , Fosfoproteínas/biosíntesis , Fosfoproteínas/química , Secuencia de Aminoácidos , Animales , Secuencia de Bases , Encéfalo/metabolismo , Cerebelo/metabolismo , Clonación Molecular , Cartilla de ADN , Biblioteca de Genes , Hipocampo/metabolismo , Humanos , Hibridación in Situ , Cinética , Macrófagos/fisiología , Ratones , Datos de Secuencia Molecular , Reacción en Cadena de la Polimerasa , ARN Mensajero/biosíntesis , Proteínas Recombinantes/biosíntesis , Proteínas Recombinantes/química , Alineación de Secuencia , Homología de Secuencia de Aminoácido , Transcripción Genética , Dominios Homologos srcRESUMEN
The superoxide-generating NADPH oxidase, dormant in resting phagocytes, is activated during phagocytosis following assembly of the membrane-integrated protein cytochrome b558 and cytosolic factors. Among the latter are the three proteins containing Src homology 3 (SH3) domains, p67phox, p47phox and p40phox. While the first two factors are indispensable for the activity, p40phox is tightly associated with p67phox in resting cells and is suggested to have some modulatory role. Here we describe a systematic analysis of the interaction between p40phox and p67phox using the yeast two-hybrid system and in vitro binding assays with recombinant proteins. Both methods unequivocally showed that the minimum requirements for stable interaction are the C-terminal region of p40phox and the region between the two SH3 domains of p67phox. This interaction is maintained even in the presence of anionic amphiphiles used for the activation of the NADPH oxidase, raising a possibility that it mediates constitutive association of the two factors in both resting and activated cells. The C-terminal region of p40phox responsible for the interaction contains a characteristic stretch of amino acids designated as the PC motif, that also exists in other signal-transducing proteins from yeast to human. Intensive site-directed mutagenesis to the motif in p40phox revealed that it plays a critical role in the binding to p67phox. Thus the PC motif appears to represent a novel module for protein-protein interaction used in a variety of signaling pathways.
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Evolución Molecular , NADPH Oxidasas/metabolismo , Fosfoproteínas/metabolismo , Dominios Homologos src , Secuencia de Aminoácidos , Sustitución de Aminoácidos , Sitios de Unión , Secuencia Conservada , Citosol/enzimología , Humanos , Datos de Secuencia Molecular , Mutagénesis Sitio-Dirigida , NADPH Oxidasas/química , Fagocitos/enzimología , Fosfoproteínas/química , Fosfoproteínas/genética , Mutación Puntual , Proteínas Recombinantes de Fusión/química , Proteínas Recombinantes de Fusión/metabolismo , Alineación de Secuencia , Homología de Secuencia de Aminoácido , TransfecciónRESUMEN
The phagocyte NADPH oxidase is activated during phagocytosis to produce superoxide, a precursor of microbicidal oxidants. The activation involves assembly of membrane-integrated cytochrome b558 comprising gp91(phox) and p22(phox), two specialized cytosolic proteins (p47(phox) and p67(phox)), each containing two Src homology 3 (SH3) domains, and the small G protein Rac. In the present study, we show that the N-terminal SH3 domain of p47(phox) binds to the C-terminal cytoplasmic tail of p22(phox) with high affinity (KD = 0.34 microM). The binding is specific to this domain among several SH3 domains including the C-terminal one of p47(phox) and the two of p67(phox) and requires the Pro156-containing proline-rich sequence but not other putative SH3 domain-binding sites of p22(phox). Replacement of Trp193 by Arg in the N-terminal SH3 domain completely abrogates the association with p22(phox). A mutant p47(phox) with this substitution is incapable of supporting superoxide production under cell-free activation conditions. These findings provide direct evidence that the interaction between the N-terminal SH3 domain of p47(phox) and the proline-rich region of p22(phox) is essential for activation of the NADPH oxidase.
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Proteínas de Transporte de Membrana , NADH NADPH Oxidorreductasas/metabolismo , NADPH Deshidrogenasa/metabolismo , Fagocitos/enzimología , Fosfoproteínas/metabolismo , Grupo Citocromo b/metabolismo , Electroforesis en Gel de Poliacrilamida , Activación Enzimática , Humanos , Cinética , NADPH Oxidasas , Mutación Puntual , Proteínas Recombinantes de Fusión/metabolismo , Relación Estructura-ActividadRESUMEN
The stereostructures of cumingianosides A-F, a series of triterpene glucosides with a 14,18-cycloapoeuphane skeleton, have been established by X-ray crystallographic analysis on an aglycone [1c] the acid hydrolysate of cumingianoside A [1], which is a potent cytotoxic triterpene against MOLT-4 human leukemia cells with an EC50 value of < 0.00625 microM. The 14,18-cyclopropane ring in cumingianoside A [1] was opened under acidic conditions in two different directions to give compounds with an apoeuphane skeleton and a dammarane skeleton. Furthermore, it was found that subsequent hydrolysis yielded not only an aglycone with an apoeuphane skeleton [1c] but also an apo-rearrangement product [1d].
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Antineoplásicos Fitogénicos/química , Glucósidos/química , Leucemia Experimental/tratamiento farmacológico , Triterpenos/química , Antineoplásicos Fitogénicos/aislamiento & purificación , Antineoplásicos Fitogénicos/farmacología , Cristalografía por Rayos X , Glucósidos/aislamiento & purificación , Glucósidos/farmacología , Humanos , Hidrólisis , Espectroscopía de Resonancia Magnética , Modelos Moleculares , Conformación Molecular , Hojas de la Planta/química , Triterpenos/aislamiento & purificación , Triterpenos/farmacología , Células Tumorales CultivadasRESUMEN
Six new ergostane glycosides, designated as petunioside A, petunioside B, 24-epipetunioside B, petunioside C, 24-epipetunioside C and petunioside D, were isolated from the methanolic extract of the fresh aerial parts of Petunia hybrida. Their structures were determined by means of spectroscopic analysis and single crystal X-ray analysis.
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Ergosterol/química , Glicósidos/química , Plantas/química , Conformación de Carbohidratos , Secuencia de Carbohidratos , Cristalografía por Rayos X , Ergosterol/análogos & derivados , Ergosterol/aislamiento & purificación , Glicósidos/aislamiento & purificación , Espectroscopía de Resonancia Magnética , Modelos Moleculares , Conformación Molecular , Datos de Secuencia Molecular , Espectrometría de Masa Bombardeada por Átomos VelocesRESUMEN
The expression of c-oncogenes was examined with normal human fibroblasts (WI-38) and the cells transformed in vitro by gamma-irradiation (CT-1). The amount of Ki-ras-specific mRNA in CT-1 cells was found to be approximately twice that in WI-38 cells. By Southern blot hybridization, the c-Ki-ras 2 gene of CT-1 cells was found to be amplified about two-fold. CT-1 cells have higher levels of c-myc mRNA than normal cells, although the gene dosage and the restriction nuclease pattern of the c-myc gene was the same. The content of c-myc mRNA in CT-1 cells was found to be constitutively high, whereas that in normal cells was increased by serum addition.