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91.
Rodrigo O. Marañón Claudio M. Joo Turoni Alfredo Coviello María Peral de Bruno 《Journal of comparative physiology. B, Biochemical, systemic, and environmental physiology》2009,179(4):403-409
Little is known about the vascular actions of angiotensin II (Ang II) and nitric oxide (NO) in Amphibia. This study investigated
(1) Ang II contractility, (2) NO concentrations, and (3) correlations between Ang II contractility, NO concentration and mean
arterial pressure (MAP) in isolated Bufo arenarum toad aortic rings. Contractility was measured in isometric conditions, NO concentrations were determined by the Griess reaction,
and MAP was determined by a direct method. In isolated toad aortic rings, Ang II produced a contractile response (292.7 ± 89.2 mg;
n = 20). Furthermore, a contractile response to norepinephrine (NE) was also obtained. A significant correlation between both
the Ang II and NE contractile responses was found (r = 0.89; n = 11; P < 0.01). Administration of Ang II increased MAP values (Basal 16.8 ± 1.7; n = 19 vs. Ang II 28.4 ± 1.8 mmHg; n = 19; P < 0.001), and the increase of MAP by Ang II was positively correlated with the Ang II contractile response (P < 0.01). Administration of L-NAME also increased MAP values, and this effect was higher in those toads that presented a lower
pressure response to Ang II (Pearson r = −0.68; P < 0.05). NO was present in all aortic rings, and its concentrations were negatively related to the Ang II contractile response
(P < 0.036) and pressure response (Pearson r = −7.08; P < 0.001). These findings suggest that, in the B. arenarum toad, the NO system contra-regulates both the contractile and pressure Ang II responses, although its action could be different
in each specimen. 相似文献
92.
93.
We report new polymorphic microsatellites for three species of Palearctic green toads (Bufo viridis subgroup): 10 in B. balearicus and seven each in B. siculus and B. boulengeri. Diversity at these loci, measured for 27 B. balearicus, 23 B. siculus and 11 B. boulengeri, ranged from low to high (two to 10 alleles). Mitotyping primers, specific to the control region, which allow fast screening of parapatric Sicilian endemic B. siculus and Italian mainland-origin B. balearicus, were developed. 相似文献
94.
MATTHEW J. GREENLEES BENJAMIN L. PHILLIPS RICHARD SHINE 《Biological journal of the Linnean Society. Linnean Society of London》2010,100(2):329-336
As well as their direct ecological impacts on native taxa, invasive species can impose selection on phenotypic attributes (morphology, physiology, behaviour, etc.) of the native fauna. In anurans, body size at metamorphosis is a critical life‐history trait: for most challenges faced by post‐metamorphic anurans, larger size at metamorphosis probably enhances survival. However, our studies on Australian frogs (Limnodynastes convexiusculus) show that this pattern can be reversed by the arrival of an invasive species. When metamorph frogs first encounter invasive cane toads (Bufo marinus), they try to eat the toxic invader and, if they are able to do so, are likely to die from poisoning. Because frogs are gape‐limited predators, small metamorphs cannot ingest a toad and thus survive long enough to disperse away from the natal pond (and thus from potentially deadly toads). These data show that larger size at metamorphosis can reduce rather than increase anuran survival rates, because larger metamorphs are more easily able to ingest (and thus be poisoned by) metamorph cane toads. Our results suggest that patterns of selection on life‐history traits of native taxa (such as size and age at metamorphosis, seasonal timing of breeding and duration of pondside aggregation prior to dispersal) can be modified by the arrival of an invasive species. © 2010 The Linnean Society of London, Biological Journal of the Linnean Society, 2010, 100 , 329–336. 相似文献
95.
中国林蛙与中华蟾蜍蝌蚪颅骨形态的系统进化比较 总被引:1,自引:0,他引:1
对无尾两栖动物系统进化的研究,主要是基于经典的形态学、现代分子生物学等技术。无尾两栖动物蝌蚪的进化与成体的进化可能是两个独立的过程,所以无尾两栖类蝌蚪形态及发育特征也可以作为研究系统进化的重要指征。本文对中国林蛙(Rana chensinensis)及中华蟾蜍(Bufo gargarizans)变态前蝌蚪的软骨性颅骨及鳃部骨骼进行形态学描述,基于幼体形态特征,进行系统建树。建树结果支持Orton将无尾两栖类蝌蚪划分为4种类型,认为最原始的类群为Ⅲ型蝌蚪,与Tihen的观点一致。新蛙亚目的中国林蛙和中华蟾蜍蝌蚪属Ⅳ型,是最进化的类群。 相似文献
96.
Aurélie Aubry Emeline Bécart John Davenport Mark Charles Emmerson 《Population Ecology》2010,52(3):437-450
The development of methods providing reliable estimates of demographic parameters (e.g., survival rates, fecundity) for wild
populations is essential to better understand the ecology and conservation requirements of individual species. A number of
methods exist for estimating the demographics of stage-structured populations, but inherent mathematical complexity often
limits their uptake by conservation practitioners. Estimating survival rates for pond-breeding amphibians is further complicated
by their complex migratory and reproductive behaviours, often resulting in nonobservable states and successive cohorts of
eggs and tadpoles. Here we used comprehensive data on 11 distinct breeding toad populations (Bufo calamita) to clarify and assess the suitability of a relatively simple method [the Kiritani–Nakasuji–Manly (KNM) method] to estimate
the survival rates of stage-structured populations with overlapping life stages. The study shows that the KNM method is robust
and provides realistic estimates of amphibian egg and larval survival rates for species in which breeding can occur as a single
pulse or over a period of several weeks. The study also provides estimates of fecundity for seven distinct toad populations
and indicates that it is essential to use reliable estimates of fecundity to limit the risk of under- or overestimating the
survival rates when using the KNM method. Survival and fecundity rates for B. calamita populations were then used to define population matrices and make a limited exploration of their growth and viability. The
findings of the study recently led to the implementation of practical conservation measures at the sites where populations
were most vulnerable to extinction. 相似文献
97.
98.
99.
Maciel NM Schwartz CA Rodrigues Pires Júnior O Sebben A Castro MS Sousa MV Fontes W Ferroni Schwartz EN 《Comparative biochemistry and physiology. Part B, Biochemistry & molecular biology》2003,134(4):641-649
The composition of indolealkylamines of Bufo rubescens cutaneous secretions was compared to those from six other Brazilian bufonids. Skin, parotoid and tibial gland secretions were obtained for analysis by thin-layer chromatography. A triple-quadrupole mass spectrometer was used to confirm the indolealkylamines standards (serotonin, 5-HT; bufotenin, BTN; dehydrobufotenin, DHB and bufotenidin, BTD). We observed clear variation in the composition of indolealkylamines of the cutaneous secretions studied and also between those found in the skin and parotoid gland secretions of the same species. We discuss the utility of indolealkylamines to the phylogeny of this group of toads. 相似文献
100.
The recent decline and extinction of amphibian species is a worldwide phenomenon without an identified cause or solution. Assisted reproductive technologies, including sperm cryopreservation, are required to manage endangered amphibian species and preserve their genetic diversity. This study on the Anuran amphibian (Bufo marinus) was undertaken to determine the feasibility of cryopreservation of amphibian sperm. Sperm suspensions for cryopreservation were prepared by macerating testes in cryoprotective additives of 10% (w/v) sucrose or 10% (w/v) sucrose containing either 10, 15, or 20% (v/v) glycerol or 10, 15, or 20% (v/v) dimethyl sulfoxide (Me2SO). Suspensions were then cooled to −85°C using a controlled rate cooler, stored in LN2, and thawed in air. The motility and fertilization rate of cryopreserved suspensions and unfrozen control suspensions in Simplified Amphibian Ringer were compared. Sucrose alone had no cryoprotective effect. All other treatments showed varying degrees of recovery of motility and fertilizing capacity. High rates of recovery of motility and fertilizing capacity were observed with 15% Me2SO (68.9 ± 3.8 and 60.5 ± 4.7%) and 20% glycerol (58.0 ± 5.9 and 81.4 ± 4.3%), respectively. Motility and fertilization rates were similar with Me2SO but diverged with glycerol as cryoprotectant. The data demonstrate the feasibility of using sperm cryopreservation with amphibian species. 相似文献