Habitat use by the South-American rattlesnake (Crotalus durissus) in south-eastern Brazil

Habitat use affects food intake, reproductive fitness and body temperature control in reptiles. Habitat use depends on both the characteristics of the animal and the environmental heterogeneity. In this study we investigated habitat use in a population of the South-American rattlesnake, Crotalus durissus, in a cerrado (the Brazilian savanna) remnant, in south-eastern Brazil. In general, snakes appeared to be thermal generalists. However, they showed substrate temperature preferences in the rainy season, when they selected colder substrates during the day and warmer substrates at night. Individuals were predominantly active on the surface and more frequently found under bushes. Furthermore, in general, the principal component analysis results indicate that rattlesnakes are generalists regarding the microhabitat variables examined in this study. These habitat characteristics, associated with a low thermal selectivity, indicate that rattlesnakes are able to colonize deforested areas where shade occurrence and vegetation cover are similar to those in the cerrado.

Circadian Pattern of Wheel-Running Activity of a South American Subterranean Rodent (Ctenomys cf knightii)

Circadian rhythms are regarded as essentially ubiquitous features of animal behavior and are thought to confer important adaptive advantages. However, although circadian systems of rodents have been among the most extensively studied, most comparative biology is restricted to a few related species. In this study, the circadian organization of locomotor activity was studied in the subterranean, solitary north Argentinean rodent, Ctenomys knightii. The genus, Ctenomys, commonly known as Tuco-tucos, comprises more than 50 known species over a range that extends from 12S latitude into Patagonia, and includes at least one social species. The genus, therefore, is ideal for comparative and ecological studies of circadian rhythms. Ctenomys knightii is the first of these to be studied for its circadian behavior. All animals were wild caught but adapted quickly to laboratory conditions, with clear and precise activity-rest rhythms in a light-dark (LD) cycle and strongly nocturnal wheel running behavior. In constant dark (DD), the rhythm expression persisted with free-running periods always longer than 24h. Upon reinstatement of the LD cycle, rhythms resynchronized rapidly with large phase advances in 7/8 animals. In constant light (LL), six animals had free-running periods shorter than in DD, and 4/8 showed evidence of splitting. We conclude that under laboratory conditions, in wheel-running cages, this species shows a clear nocturnal rhythmic organization controlled by an endogenous circadian oscillator that is entrained to 24h LD cycles, predominantly by light-induced advances, and shows the same interindividual variable responses to constant light as reported in other non-subterranean species. These data are the first step toward understanding the chronobiology of the largest genus of subterranean rodents.

A Rare Case of Trisomy 15pter-q21.2 Due to a De Novo Marker Chromosome

Supernumerary marker chromosomes (sSMC) may or may not be associated with an abnormal phenotype, depending on the presence of euchromatin, on their chromosomal origin and whether they are inherited. Over 80% of sSMCs are derived from acrocentric chromosomes and half of them include the short arm of chromosome 15. Generally, they appear as bisatellited isodicentric marker chromosomes, most of them are symmetric. These chromosomes are normally originated de novo and are associated with mild to severe intellectual disability but not with physical abnormalities. We report on a patient with an SMC studied using classical and molecular cytogenetic procedures (G and C banding, NOR staining, painting and centromeric fluorescent in situ hybridization (FISH), BAC-FISH, and SKY). The MLPA technique and DNA polymorphic markers were used in order to identify its parental origin. The marker chromosome, monosatellited and monocentric, was found to be derived from a maternal chromosome 15 and was defined as 15pter-q21.2. This is the report of the largest de novo monosatellited 15q marker chromosome ever published presenting detailed cytogenetic and clinical data. It was associated with a phenotype including cardiac defect, absence of septum pellucidum, and dysplasia of the corpus callosum. (C) 2010 Wiley-Liss, Inc.

Evidence of a genetic bottleneck in an El Nino affected population of South American fur seals, Arctocephalus australis

The South American fur seal, Arctocephalus australis, was one of the earliest otariid seals to be exploited by humans: at least 6000 years ago on the Atlantic coast and 4000 on the Pacific coast of South America. More than 750,000 fur seals were killed in Uruguay until 1991. However, a climatological phenomenon-the severe 1997-1998 El Nino Southern Oscillation (ENSO)-was responsible for the decline of 72% Of the Peruvian fur seal population due to starvation as a consequence of warming of sea-surface temperatures and primary productivity reduction. Currently, there is no precise information on global population size or on the species` conservation status. The present study includes the first bottleneck test for the Pacific and Atlantic populations of A. australis based on the analysis of seven microsatellite loci. Genetic bottleneck compromises the evolutionary potential of a population to respond to environmental changes. The perspective becomes even more alarming due to current global warming models that predict stronger and more frequent ENSO events in the future. Our analysis found moderate support for deviation from neutrality-equilibrium for the Pacific population of fur seals and none for the Atlantic population. This difference among population reflects different demographic histories, and is consistent with a greater reduction in population size in the Pacific. Such an event could be a result of the synergic effects of recurrent ENSO events and the anthropogenic impact (sealing and prey overfishing) on this population.

Chromosome homologies of the highly rearranged karyotypes of four Akodon species (Rodentia, Cricetidae) resolved by reciprocal chromosome painting: the evolution of the lowest diploid number in rodents

Traditionally comparative cytogenetic studies are based mainly on banding patterns. Nevertheless, when dealing with species with highly rearranged genomes, as in Akodon species, or with other highly divergent species, cytogenetic comparisons of banding patterns prove inadequate. Hence, comparative chromosome painting has become the method of choice for genome comparisons at the cytogenetic level since it allows complete chromosome probes of a species to be hybridized in situ onto chromosomes of other species, detecting homologous genomic regions between them. In the present study, we have explored the highly rearranged complements of the Akodon species using reciprocal chromosome painting through species-specific chromosome probes obtained by chromosome sorting. The results revealed complete homology among the complements of Akodon sp. n. (ASP), 2n = 10; Akodon cursor (ACU), 2n = 15; Akodon montensis (AMO), 2n = 24; and Akodon paranaensis (APA), 2n = 44, and extensive chromosome rearrangements have been detected within the species with high precision. Robertsonian and tandem rearrangements, pericentric inversions and/or centromere repositioning, paracentric inversion, translocations, insertions, and breakpoints, where chromosomal rearrangements, seen to be favorable, were observed. Chromosome painting using the APA set of 21 autosomes plus X and Y revealed eight syntenic segments that are shared with A. montensis, A. cursor, and ASP, and one syntenic segment shared by A. montensis and A. cursor plus five exclusive chromosome associations for A. cursor and six for ASP chromosome X, except for the heterochromatin region of ASP X, and even chromosome Y shared complete homology among the species. These data indicate that all those closely related species have experienced a recent extensive process of autosomal rearrangement in which, except for ASP, there is still complete conservation of sex chromosomes homologies.

Effect of substrate on the locomotion behaviour of the South American iguanian lizard Polychrus acutirostris

Arboreal and terrestrial habitats impose different constraints on tetrapod locomotion. We studied Polychrus acutirostris, a tree-dwelling lizard that also moves on the ground, in order to evaluate the effects of support incline and diameter on locomotion parameters. Limb movements of six specimens were filmed to quantify kinematic variables (velocity, stride frequency, stride length, and limb coordination) on distinct perch diameters (4.0, 1.5, 0.8 cm) and inclines (90, 45, and on level ground). The results show a notable slowness in arboreal habitat combined with a relatively fast locomotion when using the ground as temporary habitat. These animals developed walking trots mainly using lateral sequence. Non-symmetrical trots adopted at the highest velocities on the ground indicate difficulties of ""accommodation"" to the constraints imposed by this condition. Velocity generally decreases with the decreasing diameter, and with increasing incline, of the supports. Slowness, gaits favouring the body stability, elective role of the stride frequency in the modulation of the speed, and the role of the hindlimb in the force exchange to propel the body, constitute the main features of the locomotion pattern of P. acutirostris.

Pleistovultur nevesi gen. et sp nov (Aves: Vulturidae) and the diversity of condors and vultures in the South American Pleistocene

Pleistovultur nevesi, a new genus and species of a large Vulturidae is described from the Upper Pleistocene or beginning of the Holocene, based on a complete and well preserved right tibiotarsus from the Cuvieri cave deposits, one of the hundreds of caves of the Lagoa Santa region in Minas Gerais state, Brazil. Also described here is a distal half of a left tibiotarsus from Gruta dos Brejoes, a cave in Morro do Chapeu, Bahia state, Brazil, which probably belongs to another not-yet-known genus and species of the Vulturidae. The described material, added to prior literature, is proof of the appreciable diversity of the Vulturidae during the Pleistocene in South America.

Locomotion patterns in two South American gymnophthalmid lizards: Vanzosaura rubricauda and Procellosaurinus tetradactylus

We quantified gait and stride characteristics (velocity, frequency, stride length, stance and swing duration, and duty factor) in the bursts of locomotion of two small, intermittently moving, closely related South American gymnophthalmid lizards: Vanzosaura rubricauda and Procellosaurinus tetradactylus. They occur in different environments: V rubricauda is widely distributed in open areas with various habitats and substrates, while P. tetradactylus is endemic to dunes in the semi-arid Brazilian Caatinga. Both use trot or walking trot characterised by a lateral sequence. For various substrates in a gradient of roughness (perspex, cardboard, sand, gravel), both species have low relative velocities in comparison with those reported for larger continuously moving lizards. To generate velocity, these animals increase stride frequency but decrease relative stride length. For these parameters, P. tetradactylus showed lower values than V rubricauda. In their relative range of velocities, no significant differences in stride length and frequency were recorded for gravel. However, the slopes of a correlation between velocity and its components were lower in P. tetradactylus on cardboard, whereas on sand this was only observed for velocity and stride length. The data showed that the difference in rhythmic parameters between both species increased with the smoothness of the substrates. Moreover, P. tetradactylus shows a highly specialised locomotor strategy involving lower stride length and frequency for generating lower velocities than in V. rubricauda. This suggests the evolution of a central motor pattern generator to control slower limb movements and to produce fewer and longer pauses in intermittent locomotion. (c) 2008 Elsevier GmbH. All rights reserved.

Evolution of Dendrocolaptes platyrostris (Aves: Furnariidae) between the South American open vegetation corridor and the Atlantic forest

The open vegetation corridor of South America is a region dominated by savanna biomes. It contains forests (i.e. riverine forests) that may act as corridors for rainforest specialists between the open vegetation corridor and its neighbouring biomes (i.e. the Amazonian and Atlantic forests). A prediction for this scenario is that populations of rainforest specialists in the open vegetation corridor and in the forested biomes show no significant genetic divergence. We addressed this hypothesis by studying plumage and genetic variation of the Planalto woodcreeper Dendrocolaptes platyrostris Spix (1824) (Aves: Furnariidae), a forest specialist that occurs in both open habitat and in the Atlantic forest. The study questions were: (1) is there any evidence of genetic continuity between populations of the open habitat and the Atlantic forest and (2) is plumage variation congruent with patterns of neutral genetic structure or with ecological factors related to habitat type? We used cytochrome b and mitochondrial DNA control region sequences to show that D. platyrostris is monophyletic and presents substantial intraspecific differentiation. We found two areas of plumage stability: one associated with Cerrado and the other associated with southern Atlantic Forest. Multiple Mantel tests showed that most of the plumage variation followed the transition of habitats but not phylogeographical gaps, suggesting that selection may be related to the evolution of the plumage of the species. The results were not compatible with the idea that forest specialists in the open vegetation corridor and in the Atlantic forest are linked at the population level because birds from each region were not part of the same genetic unit. Divergence in the presence of gene flow across the ecotone between both regions might explain our results. Also, our findings indicate that the southern Atlantic forest may have been significantly affected by Pleistocene climatic alteration, although such events did not cause local extinction of most taxa, as occurred in other regions of the globe where forests were significantly affected by global glaciations. Finally, our results neither support plumage stability areas, nor subspecies as full species. (C) 2011 The Linnean Society of London, Biological Journal of the Linnean Society, 2011, 103, 801-820.

Annual profile of fecal androgen and glucocorticoid levels in free-living male American kestrels from southern mid-latitude areas

Fecal samples and behavioral data were collected at a fortnightly basis during 11 months period from free-living male American kestrels living in southeast Brazil (22 degrees S latitude). The aim was to investigate the seasonal changes in testicular and adrenal steroidogenic activity and their correlation to reproductive behaviors and environmental factors. The results revealed that monthly mean of fecal glucocorticoid metabolites in May and June were higher than those estimated in November. in parallel, monthly mean of androgen metabolites in September was higher than those from January to April and from October to November. Molt took place from January to March, whereas copulation was observed from June to October but peaked in September. Nest activity and food transfer to females occurred predominantly in October, and parental behavior was noticed only in November. Territorial aggressions were rare and scattered throughout the year. Multiple regression analysis revealed that fecal androgen levels are predicted by photoperiod and copulation, while fecal glucocorticoid levels are only predicted by photoperiod. Bivariate correlations showed that fecal androgen metabolites were positively correlated with fecal glucocorticoid metabolites and copulation, but negatively correlated with molt. Additionally, copulation was positively correlated with food transfer to females and nest activity, but negatively correlated with molt. These findings suggest that male American kestrels living in southeast Brazil exhibit significant seasonal changes in fecal androgen and glucocorticoid concentrations, which seem to be stimulated by decreasing daylength but not by rainfall or temperature. (C) 2009 Elsevier Inc. All rights reserved.

Influence of Radiotransmitters on Fecal Glucocorticoid Levels of Free-Ranging Male American Kestrels

Although radiotelemetry is considered a valuable technique for ornithological field studies, several assumptions have been made about the impact that transmitters may have on the estimation of behavioral, ecological, and reproductive parameters. To assess the potential effects of backpack radiotransmitters, we captured and assigned 8 male American kestrels (Falco sparverius) into 2 groups: radiotagged (n = 6) and control individuals (leg-banded, n = 2). Thereafter, we collected feces approximately 2 hours after capture (day -1), and subsequently during days 0 (releasing day), 4, 7, 15, 30, 40, and 55. Prior to fecal analysis, we validated the corticosterone enzyme immunoassay using standard procedures (e. g., parallelism, dose-response curve), and we confirmed physiological significance of fecal glucocorticoid metabolites through adrenocorticotropin challenge, which induced an increase of 4-fold (446.10 +/- 60.73 ng/g) above baseline (114.27 +/- 15.23 ng/g) within 4 hours (P < 0.001). Both groups exhibited a significant increase in fecal glucocorticoids during day 0 (P < 0.001), but concentrations returned to preattachment values within 4 days. Fecal glucocorticoid concentrations did not differ between samples of radiotagged and leg-banded kestrels (P > 0.05). In spite of the small number of monitored subjects, these findings suggested that radiotransmitters did not affect adrenocortical activity in these male American kestrels. (JOURNAL OF WILDLIFE MANAGEMENT 73(5): 772-778; 2009)

(65)Zn(2+) transport by isolated gill epithelial cells of the American lobster, Homarus americanus

Gills are the first site of impact by metal ions in contaminated waters. Work on whole gill cells and metal uptake has not been reported before in crustaceans. In this study, gill filaments of the American lobster, Homarus americanus, were dissociated in physiological saline and separated into several cell types on a 30, 40, 50, and 80% sucrose gradient. Cells from each sucrose solution were separately resuspended in physiological saline and incubated in (65)Zn(2+) in order to assess the nature of metal uptake by each cell type. Characteristics of zinc accumulation by each kind of cell were investigated in the presence and absence of 10 mM calcium, variable NaCl concentrations and pH values, and 100 mu M verapamil, nifedipine, and the calcium ionophore A23187. (65)Zn(2+) influxes were hyperbolic functions of zinc concentration (1-1,000 mu M) and followed Michaelis-Menten kinetics. Calcium reduced both apparent zinc binding affinity (K (m)) and maximal transport velocity (J (max)) for 30% sucrose cells, but doubled the apparent maximal transport velocity for 80% sucrose cells. Results suggest that calcium, sodium, and protons enter gill epithelial cells by an endogenous broad-specificity cation channel and trans-stimulate metal uptake by a plasma membrane carrier system. Differences in zinc transport observed between gill epithelial cell types appear related to apparent affinity differences of the transporters in each kind of cell. Low affinity cells from 30% sucrose were inhibited by calcium, while high affinity cells from 80% sucrose were stimulated. (65)Zn(2+) transport was also studied by isolated, intact, gill filament tips. These intact gill fragments generally displayed the same transport properties as did cells from 80% sucrose and provided support for metal uptake processes being an apical phenomenon. A working model for zinc transport by lobster gill cells is presented.

Iberia-Latin-American Symposia of Morphological Terminology (SILAT). First Two Years and Statute

On the occasion of meeting the first two years of life, it makes a review of SILAT as scientific and educational program that serves as a tool to analyze and solve the problems of morphological medical terminology in the countries of Hispanic and Portuguese-speaking America. It describes the basis of its creation, strategy and scope in the region, the founding years and its immediate future. Finally, some conclusions are indicated and it Statute is annexed.

Ibero-Latin-American Symposium of Morphological Terminology. General Characteristics

It describes the main features of SILAT as a multinational scientific and educational program that serves as a tool to analyze and solve the morphological medical terminology problems in Spanish and Portuguese speaking countries of America. It treated history and creation, members, aims and functions, resources, activities, organizational structure, board, relations with other organizations and publications.

Role of a Novel Tetrodotoxin-Resistant Sodium Channel in the Nitrergic Relaxation of Corpus Cavernosum from the South American Rattlesnake Crotalus Durissus Terrificus

Introduction. Coitus in snakes may last up to 28 hours; however, the mechanisms involved are unknown. Aim. To evaluate the relevance of the nitric oxide (NO)-cyclic guanosine monophosphate (cGMP)-phosphodiesterase type 5 (PDE5) system in snake corpus cavernosum reactivity. Methods. Hemipenes were removed from anesthetized South American rattlesnakes (Crotalus durissus terrificus) and studied by light and scanning electronic microscopy. Isolated Crotalus corpora cavernosa (CCC) were dissected from the non-spiny region of the hemipenises, and tissue reactivity was assessed in organ baths. Main Outcome Measures. Cumulative concentration-response curves were constructed for acetylcholine (ACh), sodium nitroprusside (SNP), 5-cyclopropyl-2-[1-(2-fluorobenzyl)-1H-pyrazolo[3,4-b]pyridine-3-yl]pyrimidin-4-ylamine (BAY 41-2272), and tadalafil in CCC precontracted with phenylephrine. Relaxation induced by electrical field stimulation (EFS) was also done in the absence and presence of N omega nitro-L-arginine methyl ester (L-NAME; 100 mu M), 1H-[1, 2, 4] oxadiazolo[4,3-a]quinoxalin-1-one (ODQ; 10 mu M) and tetrodotoxin (TTX; 1 mu M). Results. The hemipenes consisted of two functionally concentric corpora cavernosa, one of them containing radiating bundles of smooth muscle fibers (confirmed by alpha-actin immunostaining). Endothelial and neural nitric oxide synthases were present in the endothelium and neural structures, respectively; whereas soluble guanylate cyclase and PDE5 were expressed in trabecular smooth muscle. ACh and SNP relaxed isolated CCC, with the relaxations being markedly reduced by L-NAME and ODQ, respectively. BAY 41-2272 and tadalafil caused sustained relaxations with potency (pEC(50)) values of 5.84 +/- 0.17 and 5.10 +/- 0.08 (N = 3-4), respectively. In precontracted CCC, EFS caused frequency-dependent relaxations that lasted three times longer than those in mammalian CC. Although these relaxations were almost abolished by either L-NAME or ODQ, they were unaffected by TTX. In contrast, EFS-induced relaxations in marmoset CC were abolished by TTX. Conclusions. Rattlesnake CC relaxation is mediated by the NO-cGMP-PDE5 pathway in a manner similar to mammals. The novel TTX-resistant Na channel identified here may be responsible for the slow response of smooth muscle following nerve stimulation and could explain the extraordinary duration of snake coitus. Capel RO, Monica FZ, Porto M, Barillas S, Muscara MN, Teixeira SA, Arruda AMM, Pissinatti, L, Pissinatti A, Schenka AA, Antunes E, Nahoum C, Cogo JC, de Oliveira MA, and De Nucci G. Role of a novel tetrodotoxin-resistant sodium channel in the nitrergic relaxation of corpus cavernosum from the South American rattlesnake Crotalus durissus terrificus. J Sex Med 2011;8:1616-1625.