Browsing by Subject "Amphibians"

Now showing 1 - 11 of 11
  • Thumbnail Image
    Publication
    Open Access
    Actualización de la distribución de los anfibios de la Región de Murcia (SE Península Ibérica)
    (Murcia: Universidad de Murcia, Servicio de Publicaciones, 2005) Egea Serrano, Andrés; Oliva Paterna, Francisco José; Miñano, Pedro A.; Verdiell Cubedo, David; Maya, José Antonio de; Zoología y Antropología Física; Facultad de Biología
    Se actualiza la distribución de la comunidad de anfibios presente en la Región de Murcia. Durante el período 2002-2004 se detectó la pre sencia en el área de estudio de nueve especies de anuros y una de urodelo. Para la mayor parte de estas especies ha sido registrada una reducción de sus áreas de distribución respecto a estudios previos. Las tipologías de cuerpo de agua donde se ha constatado la repro- ducción de la mayor parte de las especies detectadas corresponden a balsas, siendo los principales factores de amenaza a los que están expuestos estos cuerpos de agua la modificación del medio acuático y la presencia de vertidos.
  • Thumbnail Image
    Publication
    Open Access
    Alterations induced by E-cadherin and ß-catenin antibodies during the development of Buto arenarum (Anura-Bufonidae)
    (F. Hernández y Juan F. Madrid. Universidad de Murcia: Departamento de Biología Celular e Histología, 2001) Izaguirre, M. F.; Adur, J. F.; Peralta Soler, A.; Casco, V. H.
    E(e pi theli al)-ca dh erin is a member of a ca lcium-dependent famil y of cell surface glycoproteins in vo lved in ce ll- ce ll adh esion and mo rph oge nesis. Catenins are a large family of proteins that connect the cad herins to the cytoskeleton. They are import ant for cadherin fUll ction and for transducing signals involved in specification of ce ll fate during embryogenesis. The best charac teri zed ca tenin s in clude U - , /3- , Yo, and p1 20- ca tenin. Usin g spec ifi c antibodi es, we studi ed th e ex pression and distribution of E-cadherin, and u- and /3 - catenin in developmental stages of Bufo arellarum toad. The three proteins were fo und co-locali zed in stages 19 to 41 of development. Surprisingly, E-cadherin was the only of these three proteins fo und earlier than stage 19. To test whe th e r E-ca dh e rin a nd /3- ca te nin have a functional role in B/./fo arenarlIIn embryogenesis, stage 17 whole embryos were incubated with anti-E-cadherin and /3-catenin antibodies. Both anti-E-cadherin and anti- /3- ca tenin antibodi es indu ced seve re morph ological alterations. However, while alterations produced by the anti-/3 -catenin antibody, showed some vari ability from the most severe (neural tube and notochord duplication) to a simple delay in deve lopment, the alterations with anti-E-cadherin were homogeneous. These observa tions suggest a critica l role for E-cadherin and/3-catenin in the ea rl y embryo ni c development of the Bufo arenarum toad. Our resul ts are consistent with the development al role of these proteins in other species. One of the most surprising findin gs was th e blockage with the anti-Bcat enin antibodi es on late r embr yo stages, and we hypothesize that the partial axes duplica tion could be medi ated by the notochord induction.
  • Thumbnail Image
    Publication
    Open Access
    Anuran inventory in a locality of the buffer area of La Amistad International Park, Costa Rica: pilot study for Citizen Science application
    (Murcia: Servicio de publicaciones de la Universidad de Murcia, 2018) Gómez-Hoyos, Diego; Méndez-Arrieta, Rafael; Méndez-Arrieta, Adams; Seisdedos-de-Vergara, Rocío; Abarca, Juan; Barrio-Amorós, Cesar; González-Maya, José
    We present an anuran inventory in the buffer area of La Amistad International Park performed by local people. Results are discussed around the Citizen Science framework and their application for amphibian studies, as well as the uncertainty level of the species’ identification by photographs. Fifteen anuran species were recorded, of which six where considered to be reliably identified, and extrapolated species richness estimate was ~20 species. We recognized the altitudinal extension range of Scinax boulengeri. In many rural areas in the Neotropic the citizens that could be involved in research are farmers. Also, the data they can provide is usually from isolated areas, and therefore can be useful for contributing on amphibian knowledge.
  • Thumbnail Image
    Publication
    Open Access
    Distribución de los anfibios en la provincia de Granada (SE Península Ibérica)
    (Murcia: Universidad de Murcia, Servicio de Publicaciones, 1990) Gracia, P.; Pleguezuelos, J.M.; Facultad de Biología
    En el presente artículo se representa la distnbución de los anfibios por medio de la malla U. T. M. de 10 x 10 km. Se ha prestado especial atención a la homogeneización del esfuerzo de muestre0 a través de las 13 1 cuadrículas en las que queda dividida la provincia de Granada. En el área de estudio se han encontrado 1 1 especies de anfibios, de las que 3 son urodelos y 8 son anuros. Por aquí pasa el límite suroriental de la distribución ibérica de los urodelos por lo que las poblaciones de las especies son escasas y puntuales; sin embargo, todas las especies de anuros presentan poblaciones más surorientales. Se ha estudiado la relación entre diversos parámetros medioambientales y la distribución de las especies; en el área de estudio el factor con más influencia es, como cabría esperar, la precipitación, seguido del número de puntos de agua, la litología caliza y la presencia de masas arbóreas o arbustivas
  • Thumbnail Image
    Publication
    Open Access
    Effects of photoperiod and temperature on testicular function in amphibians
    (Murcia : F. Hernández, 1990) Paniagua, R.; Fraile, Benito; Sáez, F.J.
    Most amphibians present an annual testicular cycle characterized by a quiescent period (late autumn-winter) and a spermatogenic period (spring and summer). At the end of the period of spermatogenesis undifferentiated interstitial cells transform into steroid-secreting Leydig cells which regress in spring at the beginning of the new spermatogenetic cycle. The testicular cycle is controlled by the pituitary gonadotropin levels which are high in autumn and winter, low in spring and increase temporarily in the middle of summer. Photoperiod and temperature seem to be the most important externa1 factors involved in the regulation of this cycle in many amphibian species since the colder the geographic area, the longer the quiescent period and the shorter the spermatogenic period. This suggests the occurrence of a potentially continuous cycle in these species, in contrast with that which occurs in other species having an endogenous rhythm of testicular function which is much less sensitive to environmental factors. Although the specific response to temperature can vary widely between species, the most frequent observation in amphibians with a potentiaiiy continuous cycle is that exposure to mild temperatures (15-20° C, according to the spring temperatures of the different geographic areas) stimulates spermatogenesis even during the period of testicular quiescence. If this mild temperature is combined with a long photoperiod, complete spermatogenesis is attained. Experiments performed during the period of germ-cell proliferation (development from spermatogonia to round spermatids) indicated that low temperatures (below 11° C) as well as short photoperiods (less than 8 h of light) hinder germcell proliferation. Moderately high temperatures (about 30° C) do not impair this proliferation. In the newt Offprint reqoests to: Dr. R. Paniagua, Department of Cell Biology and Genetics, University of AlcalA de Henares, E-28871 Alcala de Henares, Madrid, Spain Triturus marmoratus, it has been shown that an excessively long photoperiod (over 16 h) has the same effect as a short photoperiod. In this species eyes are not required for the testicular photoperiodic response. Photoperiod appears to have no effect on spermiogenesis (differentiation of round spermatids into spermatozoa), because once round spermatids are formed, spermiogenesis will occur even in total darkness. Mild temperatures seem to be necessary for spermiogenesis as well as for androgen biosynthesis because neither process will take place at extreme temperatures. Results on the effect of photoperiod in steroidogenesis differ between species.
  • Thumbnail Image
    Publication
    Open Access
    Fine structure of the retinal epithelium of the tiger salamander (Ambystoma tigrinum)
    (Murcia : F. Hernández, 1993) Braekevelt, Charlie R.
    The retinal pigment epithelium (RPE) of the tiger salamander (Ambystoma tigrinum) consists of a single layer of large squarnous-shaped cells. These RPE cells are but minimally infolded basally (sclerally) but show numerous apical (vitreal) processes that interdigitate with the photoreceptor ceiis. A series of apically-located tight junctions joins the RPE cells to form part of the blood-occular barrier. Internally the RPE nucleus is large, vesicular and flattened. Smooth endoplasmic reticulum predominates in these cells with only occasional small profiles of rough endoplasmic reticulum present. Polysomes and basally-located mitochondria are plentiful. Golgi zones, lipid droplets, lysosome-like bodies and phagosomes of outer segment material are also present. Myeloid bodies which may show ribosomes on their surface are also numerous. The round to oval melanosomes undergo retinomotor movements and in the light-adapted state reach almost to the externa1 limiting membrane. Bmch's membrane or complexus basalis shows a pentalarninate stmcture with the central elastic lamina poorly represented. The choriocapillaris is a single layer of large anastomosing capillaries which are but minimally fenestrated.
  • Thumbnail Image
    Publication
    Open Access
    Intrinsic and extrinsic innervation of the amphibians esophagic myenteric plexuses
    (Murcia : F. Hernández, 1988) Junquera, C.; Azanza, M.J.; Parra, P.; Peg, M.T.; Aisa, J.; Romero, L.M.; Garín, P.
    The innervation of Rana ridibundaesophagus myenteric plexuses has been studied by the following methods: demonstration of cholinesterase activity; FIF method for catecholamines; immunohistochemistry for VIP, SP and SOM, and conventional electron microscopy. The cholinergic innervation is important in the esophagus wall where, in addition to the well known extrinsic component, there is a rich intrinsic plexus with cells and fibres widely distributed. The esophagus, together with the intestine, are the Rana gut portions where the adrenergic component is more broadly expressed. The adrenergic innervation seems t o be almost entirely of extrinsic origin. We have shown that, forthe tested peptides, there is an intrinsic innervation represented by VIP, SP and SOM like plexuses. We do not discard nonetheless an extrinsic component. The ultrastructure reveals the morphological characteristics of the enteric neurons as well as the fine inter-relationships between the nervous elements and the functional components of the esophagic wall.
  • Thumbnail Image
    Publication
    Open Access
    Neurotrophin and Trk receptor-like immunoreactivity in the frog gastrointestinal tract
    (Murcia : F. Hernández, 2004) Maruccio, L.; Castaldo, L.; De Girolamo, P.; Lucini, C.
    Nerve growth factor (NGF), brain derived neurotrophic factor (BDNF) and neurotrophin-3 (NT-3) are members of the neurotrophin family, which is involved in the differentiation, growth, repair, plasticity and maintenance of many neuronal populations. They act through three tyrosin-kinase (Trk) specific receptors: NGF bind to TrkA, BDNF to TrkB and NT3 to TrkC. Despite increasing evidence regarding the presence of neurotrophin and their receptors in many vertebrate species, in amphibians there are very few data concerning them. Thus, the aim of this study was to extend the investigation to the presence of both neurotrophins and their Trk receptors in the gut of an anuran amphibian, Rana temporaria. In the frog gut NT-3- like immunoreactivity (IR) was observed in both the nervous system and endocrine cells of the stomach and intestine, while NGF-like IR was observed only in the enteric nervous system, and BDNFlike IR in the intestinal endocrine cells. TrkA- and TrkBlike IR was detected in both neurons and endocrine cells of the intestine, while TrkC-like IR was observed only in intestinal neurons. No Trk IR was detected in the stomach. The occurrence of the IR to neurotrophins and their receptors in the gut of the frog further confirms the wellconserved presence of this family of growth factors and Trk receptors during the evolution of vertebrates and suggests their complex involvement in the biology of the gastrointestinal neuro-endocrine system.
  • Thumbnail Image
    Publication
    Open Access
    Retinal pigment epithelial fine structure in the red-backed salamander (Plethodon cinereus)
    (Murcia : F. Hernández, 1992) Braekevelt, Charlie R.
    The retinal pigment epithelium (RPE) of the red-backed salamander (Plethodon cinerus) consists of a single layer of large squamous shaped cells. The RPE cells are but minimally infolded basally (sclerally) but show many large apical (vitreal) processes interdigitating with the rod outer segments. These epithelial cells are joined laterally by prominent tight junctions located in the mid region of the cells. Internally smooth endoplasmic reticulum is very plentiful while rough endoplasmic reticulum is not. Polysomes, small dense mitochondria and small round to oval melanosomes are plentiful. Golgi zones and lysosome-like bodies are also present as are phagosomes of outer segment material and myeloid bodies. The RPE cell nucleus is large and vesicular. It is felt that the melanosomes undergo retinomotor movements but as only light-adapted specimens were examined it is not known how extensive are these movements. Bruch's membrane or complexus basalis shows the typical pentalaminate structure noted for most vertebrates. The choriocapillaris is a single layer of large anastomosing capillaries which are minimally fenestrated facing Bruch's membrane.
  • Thumbnail Image
    Publication
    Open Access
    Riqueza de herpetofauna de la reserva natural privada Los Tarrales, Cuenca del Lago Atitlán, Guatemala
    (Murcia: Servicio de Publicaciones de la Universidad de Murcia, 2014) Guerra Centeno, Dennis; Morán Villatoro, David; Fuentes Rousselin, Héctor; Meoño Sánchez, Edy; Valdez Sandoval, Carlos
    Se investigó la riqueza de herpetofauna de la Reserva Natural Privada Los Tarrales (RNPLT), cuenca del Lago Atitlán, Guatemala mediante tres métodos: 1) captura/avistamiento de especímenes, 2) investigación social y 3) investigación documental. Se realizaron búsquedas diurnas y nocturnas. El esfuerzo de búsqueda abarcó 10 años (2003 a 2013), a razón de seis pulsos por año. El tiempo acumulado de búsqueda fue de 600 horas-transecto. Se recorrió el equivalente a 720 km de senderos, cubriendo elevaciones entre los 700 y los 1900 msnm. Tres ex-cazadores de la reserva fueron entrevistados. Se analizaron publicaciones sobre distribución de la herpetofauna para Guatemala. Se generó un listado que incluye 119 especies. Se discute la calidad y el significado de los datos generados
  • Thumbnail Image
    Publication
    Open Access
    Unauthorized translocations of threatened fauna in freshwater ecosystems: insights from the Iberian southeast
    (Wiley, 2025-07-22) Zamora Marín, José Manuel; Guerrero Gómez, Adrián; Zamora López, Antonio; Torralva, Mar; Oliva Paterna, Francisco José; Sánchez Fernández, David; Zoología y Antropología Física
    Unauthorized translocations of native and threatened wildlife are widely conducted for conservation purposes. This illegal practice remains understudied and is poorly considered by wildlife managers despite its important socioecological implications. By focusing on the southeastern Iberian Peninsula as a case study, we combined data from freshwater biodiversity monitoring programs, published records and local expert knowledge to provide a comprehensive assessment of the magnitude of unauthorized translocations in freshwater ecosystems. A total of 14 cases of covertly translocated populations were recorded, involving 10 freshwater vertebrate species (six fish and four amphibians). All these species are classified as threatened taxa (i.e., critically endangered, endangered or vulnerable) at a global, national or regional level, seven of them being Iberian endemisms. At least nine out of these unauthorized translocations have resulted in self-sustaining populations, but their impact on local biodiversity and recipient ecosystems' functioning remains to be assessed. This case study suggests that unauthorized translocations could be an emerging conservation issue in freshwater ecosystems, highlighting the need for implementing integrative management approaches to halt this illegal practice at source. These management approaches should include a more proactive attitude by environmental authorities towards official conservation translocation programs and increased social awareness of the potential impacts of unauthorized translocations.