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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
171

Fylogeneze vybraných rodů gekonů Mediteránu a přilehlých oblastí / Phylogeny of selected genera of geckos in the Mediterranean and adjacent regions

Červenka, Jan January 2014 (has links)
Phylogeny of selected genera of geckos in the Mediterranean and adjacent regions Jan Červenka Ph.D. thesis Abstract This Ph.D. thesis is composed of three published articles and one manuscript, and is focused on the phylogenetic relationships of selected species of geckos from the Mediterranean and surrounding areas. The group of geckos of interest shares the common characteristic of an absence of adhesive lamellas on their toes. Historically, it was assumed that these species were closely related. Molecular-phylogenetic approaches were used in order to reveal the phylogenetic relationships within this group, especially using the sequential data from mitochondrial genes. Morphological characteristics commonly used in lizards were studied in connection with the ecology of the group. This thesis provides the first more detailed view of the phylogeny of the studied species. The results show that the genus Cyrtopodion, previously considered as monophyletic, in fact is not monophyletic as the genera Bunopus and Agamura represent its inner groups. Mediodactylus, the subgenus of Cyrtopodion, forms monophylum but is not closely related to the other members of the genus and so was reclassified as the independent genus. The enigmatic and yet so far very poorly studied genus Carinatogecko was discovered to be the...
172

Risk assessment of the nonnative Argentine black and white Tegu, Salvator merianae, in South Florida

Unknown Date (has links)
The Argentine black and white tegu, Salvator merianae, is a nonnative species that has invaded parts of Florida. The potential impacts of this species on native Florida wildlife are not yet known. This study looks at the stomach contents of 169 S. merianae captured between 2011 and 2013 in south Florida to infer potential impacts of S. merianae and spatial or seasonal shifts in diet. Analysis of 169 GI tracts showed that S. merianae is an omnivorous, terrestrial forager with a broad dietary range which includes insects, fruits, plants, snails, crayfish, carrion, birds, small mammals, turtles, snakes, lizards, frogs and eggs. S. merianae diet composition varied with capture habitat, the fattest tegus were collected from disturbed/agricultural areas and these samples contained, primarily, gastropods and insects. Tegu dietary habits threaten local endangered and state listed species such as the American crocodile, Crocodylus acutus, and the Cape Sable seaside sparrow, Ammodramus maritimus mirabilis. Dedicated funds and efforts need to be focused on this species to limit its further spread and future impact on native species. / Includes bibliography. / Thesis (M.S.)--Florida Atlantic University, 2015. / FAU Electronic Theses and Dissertations Collection
173

O papel dos lipídios na reorganização metabólica associada à dormência sazonal no lagarto teiú Tupinambis merianae (Sauria, Teidae) / The role of lipids in the metabolic reorganization associated to seasonal dormancy in tegu lizards, Tupinambis merianae (Sauria, Teiidae)

Haddad, Laura Saade 03 December 2007 (has links)
O jejum prolongado associado `a dormência sazonal é um fenômeno característico de diversos grupos de vertebrados, e os lipídios tem se mostrado bastante importantes na manutenção destes animais. No presente estudo pretendeu-se caracterizar a reorganização metabólica no jejum de 3-4 meses associado à dormência e depressão metabólica acentuada em lagartos teiú no primeiro ciclo anual de atividades, elucidando (1) qual o papel do metabolismo lipídico e de outros substratos energéticos na regulação da massa corpórea e da taxa metabólica dos teiús jovens ao longo do primeiro ciclo anual (2) qual é o comportamento de enzimas do metabolismo energético de diferentes substratos ao longo do ciclo sazonal, relacionadas à manutenção dos teiús durante o jejum hipometabólico e no retorno a atividade. (3) qual é perfil dos ácidos graxos do plasma e diferentes tecidos ao longo do ciclo sazonal e (4) testar se as predições da teoria da membrana como marca-passo do metabolismo se aplicam a um modelo intra-específico e sazonal, de forma a explicar a regulação da acentuada depressão metabólica nos lagartos teiú Para tal, foram determinadas as atividades de enzimas das vias do metabolismo energético de carboidratos (PECK), lipídios (CPT I e CPT II) e proteínas (GOT), e foi determinada a composição lipídica do plasma e dos tecidos de reserva como os corpos gordurosos abdominais e fígado, assim como a composição de membrana do tecido hepático total e das mitocôndrias e do músculo esquelético da pata PIT na atividade de outono, dormência de inverno, despertar, animais ativos na primavera e submetidos a um jejum forçado. Os resultados em conjunto parecem indicar que embora as vias oxidativas estejam reduzidas no tecido hepático, o potencial de mobilização e oxidação de lipídios está aumentado no jejum natural, evidenciando a importância deste substrato na manutenção dos lagartos teiú, e que haveria uma mobilização seletiva de ácidos graxos enquanto outros são mantidos nos tecidos. Adicionalmente, as respostas na composição dos tecidos ao jejum forçado parecem ser diferentes em relação ao jejum natural. O presente trabalho é pioneiro a fazer uma descrição minuciosa da composição lipídica de tecidos e membranas, e o primeiro a fazer uma análise da aplicação da teoria das membranas como 90 marcapasso do metabolismo em uma comparação intra-específica em um vertebrado que exibe dormência sazonal. Esta teoria parece não se aplicar a este modelo, de forma que a regulação do metabolismo parece ser por mecanismos que não uma alteração na composição de membrana dos tecidos. / Seasonal dormancy is a widespread phenomenon among vertebrates, in which lipid stores in the body tissues constitute the major energy source during the prolonged fasting. In addition, there are recent evidence indicating a role played by the lipid metabolism and the fatty acids derived in the regulation of membrane functions, resulting in modulation of whole body metabolic rates in the organisms, as well as integrating nutritional and hormonal signals that promote metabolic responses to changes in fuel availability. The present study investigates the metabolic reorganization and lipidic and fatty acid composition in tissues and subcellular fractions from tegu lizards (Tupinambis merianae), associated with metabolic depression and fasting during seasonal dormancy. Maximum enzyme activities related to the catabolism of carbohydrates (PEPCK), lipids (CPT I, II), and proteins (GOT) in liver were estimated by spectrophotometry and radiochemical assay, the Na+K+ATPase activity was assayed in the liver by standard enzymatic methods, and the lipid and fatty acid composition were analysed in the abdominal fat bodies, plasma, skeletal muscle, and in liver whole tissue and mitochondrial fractions, using gas chromatography, during autumn activity, winter dormancy, arousal, spring activity, and in animals deprived of food for 20 days during activity. During the hypometabolic state, it was found: (1) a significant decrease in the aerobic capacity and gradual increase in the potential for oxidation of long-chain fatty acids in the mitochondria of liver tissue; (2) differential lipid and fatty acid composition in the fat bodies compared to the profiles obtained with plasma, muscle and liver tissue, suggesting selective mobilization of fatty acids; (3) no significant changes in the Na+K+ATPase activity in liver and significant changes in the total and individual fractions of MUFA and PUFA as a function of the seasonal cycle, in the opposite direction indicated by the theory of membranes as pacemakers of metabolism, suggesting however, an important role played by MUFA in the metabolic reorganization during seasonal dormancy.
174

Adding to nature : can artificial retreats be used to monitor and restore lizard populations?

Lettink, Marieke, n/a January 2008 (has links)
Artificial retreats are increasingly used to sample animal populations and in attempts to boost animal numbers in degraded habitats. Here, I test potential applications of artificial retreats for lizards inhabiting a coastal environment of high conservation value (Kaitorete Spit, New Zealand). I first conducted a pitfall-trapping survey examining the distribution and relative abundance of lizards in duneland, farmland and shrubland habitats, and tested the influence of trap placement on capture rates. Capture rates of the diurnal skinks Oligosoma maccanni (McCann�s skink) and O. nigriplantare polychroma (common skink) were highest in duneland and farmland, respectively, and were most sensitive to the distance separating traps from the nearest cover (the greater the distance, the lower the capture rate). Captures of O. lineoocellatum (spotted skink) and Hoplodactylus maculatus (common gecko) were rare. Secondly, in separate chapters I test the utility of artificial retreats for monitoring: 1) a preference trial examining relative use of three types of artificial retreats by skinks (O. maccanni and O. n. polychroma) and geckos (H. maculatus); 2) a comparison of the effectiveness of artificial retreats relative to pitfall traps for detecting cryptic and primarily nocturnal geckos (H. maculatus) following translocation; and 3) capture-recapture estimation of population parameters (survival and abundance) of H. maculatus. I found that: 1) geckos strongly preferred retreats made of Onduline over corrugated iron and concrete tiles, whereas skinks exhibited no apparent preferences; 2) artificial retreats were more effective than pitfall traps for detecting geckos following translocation; and 3) monthly survival and recapture probabilities of geckos varied with age-class and over time. Estimated survival was unexpectedly low, possibly due to excessive trap spacing. I developed a new capture-recapture model specifically for population size estimation with data from artificial retreats, which gave estimates that were up to 50% greater than those predicted by conventional capture-recapture models. I caution that permanent placement of artificial retreats in long-term studies may be inappropriate for estimation of population parameters due to potential habitat-enhancement effects and/or altered predation risk. Thirdly, I conducted a capture-recapture field experiment, using a replicated Before-After-Control-impact (BACI) design, to test the relative effects of habitat manipulation (artificial retreat addition) and partial predator removal (by fencing) on annual survival of duneland skink (O. maccanni) populations. Survival increased at sites with predator exclosures, but not at control sites or following the addition of artificial retreats, either alone or in combination with a predator exclosure. The magnitude of the increase in survival for the exclosure-only treatment was small, but sufficient to change the trajectory of an apparently stable population into an increasing one, suggesting that the population is limited by predators. Predator control, but not the addition of artificial retreats, is predicted to benefit O. maccanni. To conclude, the Onduline design developed here appears to be particularly useful for sampling cryptic, terrestrial geckos; however, artificial retreats must be used appropriately to avoid bias arising from habitat-enhancing effects and/or altered predation risk. The restoration value of artificial retreats requires further testing on other species and in areas where natural retreat sites are limited.
175

Effects of cool temperature on egg incubation, thermoregulation and physiological performance of tuatara (Sphenodon punctatus) : implications for conservation programmes

Besson, Anne Amelie, n/a January 2009 (has links)
Tuatara (Sphenodon spp.) were once widespread over both the North and the South Islands of New Zealand approximately 1000 years ago but are now restricted to offshore islands due to introduced predators and habitat destruction. The survival of tuatara is now threatened by climate change because of isolation on islands that prevent them from migrating to cooler regions, and by their limited capacity to adapt due to their long life span and low genetic diversity. The thermal suitability of cooler regions for future translocations could be the key for tuatara conservation. The overall aim of the study was to determine the effect of cool temperature on the physiology, behaviour and egg incubation of Cook Strait tuatara (Sphenodon punctatus). As well answering specific questions about tuatara and their adaptation to cool temperature this study aimed at answering general questions about the behavioural and evolutionary ecology of reptiles. I first compared the preferred body temperature, feeding responses and tolerance to cold temperature of tuatara (Sphenodon punctatus) with three lizard species that inhabit the Otago region of southern New Zealand: Hoplodactylus maculatus, Naultinus gemmeus and Oligosoma maccanni. As well as testing the co-adaptation hypothesis between preferred body temperature and physiological performance of reptiles, I wanted to determine whether tuatara (which are planned to be reintroduced from a warmer site to the Otago region) have similar responses to cool temperature as do Otago lizard species. I found that tuatara show responses to cold temperatures similar to those of lizards from southern New Zealand, suggesting that if tuatara are translocated outside of their geographical range, they are likely to survive. I then tested if tuatara were capable of modifying their thermoregulatory behaviour if translocated to a cooler region. To do so, I conducted a laboratory experiment in which tuatara were provided with three thermal treatments corresponding to the thermal environments they would experience in their current habitat and the proposed reintroduction site. Contrary to the prediction of the cost-benefit model of thermoregulation, tuatara became active thermoregulators when the thermal quality of the habitat decreased. The results suggest that the model is less applicable to cold-adapted species and that if translocated to cooler regions, tuatara will be able to adjust their thermoregulatory behaviour to their thermal environment. Tuatara are temperature-dependent sex determination (TSD) reptiles and their translocation to cooler regions could have an dramatic impact on the sex ratio of new populations. To determine if potentially lower incubation temperature would be a limiting factor for the reintroduction of tuatara, I translocated eggs to the proposed reintroduction site. Some tuatara embryos developed at the site (and later hatched in the laboratory), but incubation lasted longer than in natural nests and all hatchlings were female. This trend observed in biased sex ratio might change in the context of climate change as an increase of soil temperature by 3�C would allow the production of males at the proposed site. The present study demonstrates that the translocation of tuatara further south, outside of their current geographical range, is possible and recommended. Tuatara show similar responses to cool temperatures compared with lizards that live in southern New Zealand, they can also adjust their thermoregulatory behaviour if translocated to cooler habitats, and tuatara embryos could potentially develop successfully in cooler regions. The greatest chance for the future survival of tuatara and TSD species in general, lies in translocation to other locations that are thermally suitable.
176

The spatial ecology and phylogeography of the grand skink (Oligosoma grande) : implications for the conservation of an endangered species : a thesis presented in fulfillment of the requirements for the degree of Doctor of Philosophy in Molecular BioSciences at Massey University, Palmerston North, New Zealand

Berry, Oliver Fleetwood January 2004 (has links)
Species conservation relies on determining the mechanisms that cause endangerment. This thesis documents the conservation ecology and phylogeography of an endangered lizard, Oligosoma grande, from southern New Zealand, and tests hypotheses that may explain its endangered status. Grand skinks are large rock-dwelling lizards endemic to montane grasslands in central Otago, New Zealand. They are classified as vulnerable to extinction by IUCN criteria and are the subject of intensive management. The causes of their endangerment are not well understood, but changes to landscape connectivity caused by agricultural development have been implicated. I developed microsatellite and mitochondria1 DNA markers, and combined them with field studies to address four key problems relevant to the conservation of this species. First, I investigated the ability of newly developed analytical tools for genetic data (assignment tests) to provide qualitative and quantitative dispersal information. I show that assignment tests can provide highly accurate dispersal information, and describe the circumstances where they perform best. Second, building on these results, I combined genetic and demographic data to provide an empirical account of how two forms of agricultural landuse affect the connectivity of skink populations. I show that the nature of the vegetation matrix between skink populations both quantitatively and qualitatively affected dispersal patterns, but also that characteristics of individual populations play a role in determining dispersal dynamics. Third, following the evidence that grand skink populations were very insular, I used parentage and kinship analysis to investigate the extent of inbreeding and inbreeding avoidance behaviours. It is often assumed that close inbreeding is harmful and animals should avoid it by either dispersing after birth, or recognising and avoiding mating with kin. However, I found no evidence for inbreeding avoidance or inbreeding depression. Finally, I used phylogeographic analyses to understand the contributions of historical and contemporary processes to O. grande's rarity and fragmented distribution. I demonstrate that that the current fragmented distribution has both historical as well as recent anthropogenic origins. Some populations show evidence of recent declines that may have occurred since human settlement in New Zealand, but in addition, more ancient biogeographic processes have driven population fragmentation.
177

Assessment of the Endangered Species <i>Podarcis carbonelli</i> on a Microgeographic Scale: A Molecular, Morphological and Physiological Approach

do Amaral, Maria Clara Figueirinhas 01 August 2009 (has links)
The lizard Podarcis carbonelli is an endangered species endemic to the Iberian Peninsula. One location where this species occurs is at the Berlengas Natural Preserve, an Atlantic archipelago off the coast of Portugal. These island populations are geographically separated from nearby mainland populations. The fundamental question is, are these insular individuals distinct from the mainland populations? Four localities were chose for comparison: two island populations and two nearby coastal populations. We assessed this question using three distinct approaches: molecular, morphological and physiological approach. We sequenced the 12S RNA, the mtDNA Control Region and the 7th intron of the !-fibrinogen gene and determined genetic diversity values as well as several parameters of population structure and differentiation. Individuals from these populations were also measured for several biometric characters and their blood lactate concentration was sampled. There was no genetic variation in both the mtDNA regions analyzed. The nuclear intron revealed high levels of genetic variation, with islands having in general lower values than the mainland regions. The four populations sampled had low levels of divergence; the populations of Berlenga and Peniche were the most distinct and the populations of Farilhão and Baleal were the most similar from the four populations sampled. Morphometric analyses revealed a different pattern of similarity among populations with the population of Farilhão being the only population statistically distinct from all other populations based on mass and SVL. Furthermore, island populations were in general more similar to each other than to mainland populations, with the exception of Berlenga males which in size are more similar to the Peniche males. The analysis of the blood lactate concentration revealed that the population of Peniche has significantly lower blood lactate levels than the populations of Farilhão and Berlenga. The lack of genetic differentiation found in the populations under study is most likely due to the recent divergence of these populations. Furthermore, the genetically most different populations (Berlenga and Peniche) are not the most distinct in terms of morphology, particularly the males. This suggests that genetic drift, the most likely mechanism behind the genetic differentiation seen, is not responsible for the morphological differences observed. The morphological differences seen can be attributed to: a possible difference in age of the individuals in each population; mechanisms of natural selection that are favoring specific phenotypes in each of the populations, or phenotypic plasticity. The differences in blood lactate levels found between the population of Peniche and the island populations can be attributed to differences in predatory pressure or home range size. It is suggested that the island populations are closely monitored due to their likely isolation, low mtDNA diversity and possible higher predatory pressure than initially predicted.
178

Effects of cool temperature on egg incubation, thermoregulation and physiological performance of tuatara (Sphenodon punctatus) : implications for conservation programmes

Besson, Anne Amelie, n/a January 2009 (has links)
Tuatara (Sphenodon spp.) were once widespread over both the North and the South Islands of New Zealand approximately 1000 years ago but are now restricted to offshore islands due to introduced predators and habitat destruction. The survival of tuatara is now threatened by climate change because of isolation on islands that prevent them from migrating to cooler regions, and by their limited capacity to adapt due to their long life span and low genetic diversity. The thermal suitability of cooler regions for future translocations could be the key for tuatara conservation. The overall aim of the study was to determine the effect of cool temperature on the physiology, behaviour and egg incubation of Cook Strait tuatara (Sphenodon punctatus). As well answering specific questions about tuatara and their adaptation to cool temperature this study aimed at answering general questions about the behavioural and evolutionary ecology of reptiles. I first compared the preferred body temperature, feeding responses and tolerance to cold temperature of tuatara (Sphenodon punctatus) with three lizard species that inhabit the Otago region of southern New Zealand: Hoplodactylus maculatus, Naultinus gemmeus and Oligosoma maccanni. As well as testing the co-adaptation hypothesis between preferred body temperature and physiological performance of reptiles, I wanted to determine whether tuatara (which are planned to be reintroduced from a warmer site to the Otago region) have similar responses to cool temperature as do Otago lizard species. I found that tuatara show responses to cold temperatures similar to those of lizards from southern New Zealand, suggesting that if tuatara are translocated outside of their geographical range, they are likely to survive. I then tested if tuatara were capable of modifying their thermoregulatory behaviour if translocated to a cooler region. To do so, I conducted a laboratory experiment in which tuatara were provided with three thermal treatments corresponding to the thermal environments they would experience in their current habitat and the proposed reintroduction site. Contrary to the prediction of the cost-benefit model of thermoregulation, tuatara became active thermoregulators when the thermal quality of the habitat decreased. The results suggest that the model is less applicable to cold-adapted species and that if translocated to cooler regions, tuatara will be able to adjust their thermoregulatory behaviour to their thermal environment. Tuatara are temperature-dependent sex determination (TSD) reptiles and their translocation to cooler regions could have an dramatic impact on the sex ratio of new populations. To determine if potentially lower incubation temperature would be a limiting factor for the reintroduction of tuatara, I translocated eggs to the proposed reintroduction site. Some tuatara embryos developed at the site (and later hatched in the laboratory), but incubation lasted longer than in natural nests and all hatchlings were female. This trend observed in biased sex ratio might change in the context of climate change as an increase of soil temperature by 3�C would allow the production of males at the proposed site. The present study demonstrates that the translocation of tuatara further south, outside of their current geographical range, is possible and recommended. Tuatara show similar responses to cool temperatures compared with lizards that live in southern New Zealand, they can also adjust their thermoregulatory behaviour if translocated to cooler habitats, and tuatara embryos could potentially develop successfully in cooler regions. The greatest chance for the future survival of tuatara and TSD species in general, lies in translocation to other locations that are thermally suitable.
179

Adding to nature : can artificial retreats be used to monitor and restore lizard populations?

Lettink, Marieke, n/a January 2008 (has links)
Artificial retreats are increasingly used to sample animal populations and in attempts to boost animal numbers in degraded habitats. Here, I test potential applications of artificial retreats for lizards inhabiting a coastal environment of high conservation value (Kaitorete Spit, New Zealand). I first conducted a pitfall-trapping survey examining the distribution and relative abundance of lizards in duneland, farmland and shrubland habitats, and tested the influence of trap placement on capture rates. Capture rates of the diurnal skinks Oligosoma maccanni (McCann�s skink) and O. nigriplantare polychroma (common skink) were highest in duneland and farmland, respectively, and were most sensitive to the distance separating traps from the nearest cover (the greater the distance, the lower the capture rate). Captures of O. lineoocellatum (spotted skink) and Hoplodactylus maculatus (common gecko) were rare. Secondly, in separate chapters I test the utility of artificial retreats for monitoring: 1) a preference trial examining relative use of three types of artificial retreats by skinks (O. maccanni and O. n. polychroma) and geckos (H. maculatus); 2) a comparison of the effectiveness of artificial retreats relative to pitfall traps for detecting cryptic and primarily nocturnal geckos (H. maculatus) following translocation; and 3) capture-recapture estimation of population parameters (survival and abundance) of H. maculatus. I found that: 1) geckos strongly preferred retreats made of Onduline over corrugated iron and concrete tiles, whereas skinks exhibited no apparent preferences; 2) artificial retreats were more effective than pitfall traps for detecting geckos following translocation; and 3) monthly survival and recapture probabilities of geckos varied with age-class and over time. Estimated survival was unexpectedly low, possibly due to excessive trap spacing. I developed a new capture-recapture model specifically for population size estimation with data from artificial retreats, which gave estimates that were up to 50% greater than those predicted by conventional capture-recapture models. I caution that permanent placement of artificial retreats in long-term studies may be inappropriate for estimation of population parameters due to potential habitat-enhancement effects and/or altered predation risk. Thirdly, I conducted a capture-recapture field experiment, using a replicated Before-After-Control-impact (BACI) design, to test the relative effects of habitat manipulation (artificial retreat addition) and partial predator removal (by fencing) on annual survival of duneland skink (O. maccanni) populations. Survival increased at sites with predator exclosures, but not at control sites or following the addition of artificial retreats, either alone or in combination with a predator exclosure. The magnitude of the increase in survival for the exclosure-only treatment was small, but sufficient to change the trajectory of an apparently stable population into an increasing one, suggesting that the population is limited by predators. Predator control, but not the addition of artificial retreats, is predicted to benefit O. maccanni. To conclude, the Onduline design developed here appears to be particularly useful for sampling cryptic, terrestrial geckos; however, artificial retreats must be used appropriately to avoid bias arising from habitat-enhancing effects and/or altered predation risk. The restoration value of artificial retreats requires further testing on other species and in areas where natural retreat sites are limited.
180

Functional aspects of optic nerve regeneration

Taylor, Andrew January 2006 (has links)
[Truncated abstract] Formation and consolidation of the retinotectal projection during optic nerve regeneration has been associated with two major interlinked processes. Initially, retinal ganglion cell (RGC) axons are guided by molecular guidance cues, such as the Eph receptor tyrosine kinases and their ligands, the ephrins, to their approximately correct location and form a coarse topographic map in the optic tecum. Such axon guidance occurs in the absence of neural activity and is considered to be activity-independent. The second process involves glutamatergic excitation, whereby correctly located connections are strengthened by correlated neural activity, whilst removing inappropriately located ones thereby sharpening the topography.The second process is considered to be activitydependent. Here, a number of experiments were undertaken to further examine the interrelationships of activity-dependent and independent processes with respect to functional outcomes. Two models of optic nerve regeneration were studied. In goldfish, following optic nerve crush, regeneration is successful. … In goldfish, guidance along the medio-lateral tectal axis may occur through preordering of axons prior to entering the tectum via the appropriate medial and lateral brachium, with EphA/ephrin-A then guiding axons over the rostral-caudal axis establishing gross topography. The increase in involvement of NMDA-mediated transmission during the period of activity-dependent refinement consolidated the role of this receptor in synapse plasticity. However what triggers NMDA-mediated activity to increase is still largely unresolved, although as the factors governing receptor trafficking during development and synaptic plasticity become better understood, these can be applied to the period of plasticity associated with regenerating axons. And finally, as GABAergic inhibition appears to suppress activity-dependent refinement, means of overcoming this inhibition through 4 such methods as visual training or pharmacological intervention may have significance for mammalian regeneration.

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