Isolation of Salmonella spp. from yacare caiman (Caiman yacare) and broad-snouted caiman (Caiman latirostris) from the Argentine Chaco

Presence of Salmonella spp. was evaluated in yacare caiman (Caiman yacare) and broad-snouted caiman (Caiman latirostris) from a ranching facility in the Argentine Chaco. Crocodilian ranching programs are based on captive breeding of wild-harvested eggs and release of excess hatchlings into the wild. Samples for bacterial isolation were collected from 102 captive (35 C. yacare and 67 C. latirostris) and seven free-ranging caiman (four C. yacare and three C. latirositris) between 2001 and 2005 and from three artificially incubated C. yacare wild eggs. Two Salmonella spp. of known zoonotic potential, S. infantis and S. nottingham, were isolated from captive caiman in 2001 and 2002, respectively. This is the first report for S. nottingham in reptiles and of S. infantis in caiman. Salmonella spp. prevalence varied significantly between years, with a 77% prevalence peak in 2002. Although the cause of this increase was not confirmed, we found no correlation with the type of enclosure, caiman species, or body weight. Deteriorated physical condition of caiman hatchlings due to dietary changes in 2002 could have influenced Salmonella spp. shedding. However, external sources such as food, water, or enclosures could not be ruled out. Pathogenic Salmonella spp. present a risk for human infection. Inadvertent introduction of Salmonella spp. or other bacteria into the environment when caiman are released could pose a threat to wild caiman populations. Prophylactic measures to detect and decrease Salmonella spp. presence in caiman ranching facilities are recommended to reduce risk to humans and make caiman-ranching a sound conservation strategy for crocodilian species.     

Arrangement and innervation of the iliocostalis and longissimus muscles of the brown caiman (Caiman crocodilus fuscus: Alligatoridae, Crocodilia).

The axial musculature of the brown caiman was investigated in detail with particular attention to the nerve supply, using a binocular stereomicroscope. Due to the prominent development of the longissimus (Lo) and the iliocostalis (IC) muscles of the caiman, the pattern of distribution of the spinal nerves in the body wall was unique; there also was less differentiation of the external intercostalis. There were four primary divisions of the spinal nerves in the thoracic region of the caiman, from ventral to dorsal: the intercostal nerve, the IC nerve, the Lo nerve, and the dorsal main trunk. Thus, the classic concept of the organization of the spinal nerves may not be suitable for the caiman. These findings suggest that evolutionary changes in the dorsolateral axial musculature have brought about the rearrangement of the organization of the spinal nerves. In addition, each clearly segmented myotome of the Lo and IC was innervated by more than two segments of the spinal nerves (plurisegmental innervation). The manner of formation of the myotome and its innervation is discussed from the viewpoint of comparative and developmental anatomy.     

Coccidian parasites (Apicomplexa: Eimeriidae) from two species of caimans, Caiman yacare daudin and Caiman latirostris daudin (Alligatoridae), from Paraguay

From October 1986 to January 1987, feces from 119 Caiman yacare and 12 Caiman latirostris were collected in Paraguay and later examined for coccidian oocysts; 69 of 119 (58%) samples from C. yacare and 3 of 12 (25%) samples from C. latirostris contained coccidian oocysts. Two eimerians infected C. yacare and both are described as new species. Sporulated oocysts of Eimeria paraguayensis n. sp. are ellipsoid, 34.0 x 23.6 (26-38 x 20-29) microns with sporocysts ovoid, 14.0 x 7.1 (10-19 x 6-10) microns. Sporulated oocysts of Eimeria caimani n. sp. are spheroid, 22.4 (19-29) microns with sporocysts ovoidal, 12.9 x 6.5 (8-17 x 5-8) microns. Isospora jacarei infected C. latirostris and is redescribed. Sporulated oocysts of I. jacarei are sub-spheroid, 13.2 x 12.1 (10-18 x 10-15) microns with sporocysts ellipsoid, 10.4 x 5.8 (7-13 x 4-11) microns. To date, members of the Eimeriidae found in Crocodylia include 5 species of Eimeria and 2 of Isospora including the new species described here.     

Comparative ontogenetic shape changes in the skull of Caiman species (Crocodylia,Alligatoridae)

Ontogenetic shape changes in the skull of three species of the genus Caiman (C. latirostris, C. sclerops, and C. yacare) are compared by geometric morphometrics for three-dimensional configurations (the least-squares analysis). The technique for obtaining the landmark coordinates is a simplification of the algorithm for multidimensional scaling. The ontogenetic nonlinear shape changes are similar in the three species but occur in a lesser extent in C. latirostris. These seem to be correlated with functional changes in the skull. The uniform shape change corresponds to an elongation of the skull, dorsoventral flattening, and lateral compression in C. sclerops and C. yacare. There is some lateral broadening in C. latirostris. Differences in the ontogenetic processes probably cause the differences in diet observed between C. latirostris and the other two species. Neotenic evolution seems to have acted in the skull of C. latirostris, and a posterior amplification of the early divergence led to a repatterning of the shape ontogenetic trajectory in this species. J. Morphol. 231:53–62, 1997. © 1997 Wiley-Liss, Inc.     

Evolutionary history of trypanosomes from South American caiman (Caiman yacare) and African crocodiles inferred by phylogenetic analyses using SSU rDNA and gGAPDH genes

In this study, using a combined data set of SSU rDNA and gGAPDH gene sequences, we provide phylogenetic evidence that supports clustering of crocodilian trypanosomes from the Brazilian Caiman yacare (Alligatoridae) and Trypanosoma grayi, a species that circulates between African crocodiles (Crocodilydae) and tsetse flies. In a survey of trypanosomes in Caiman yacare from the Brazilian Pantanal, the prevalence of trypanosome infection was 35% as determined by microhaematocrit and haemoculture, and 9 cultures were obtained. The morphology of trypomastigotes from caiman blood and tissue imprints was compared with those described for other crocodilian trypanosomes. Differences in morphology and growth behaviour of caiman trypanosomes were corroborated by molecular polymorphism that revealed 2 genotypes. Eight isolates were ascribed to genotype Cay01 and 1 to genotype Cay02. Phylogenetic inferences based on concatenated SSU rDNA and gGAPDH sequences showed that caiman isolates are closely related to T. grayi, constituting a well-supported monophyletic assemblage (clade T. grayi). Divergence time estimates based on clade composition, and biogeographical and geological events were used to discuss the relationships between the evolutionary histories of crocodilian trypanosomes and their hosts.     

Macrogeographic genetic variation in broad-snouted caiman (Caiman latirostris)

Broad-snouted caiman's (Caiman latirostris) geographic distribution comprises one of the widest latitudinal ranges among all crocodilians. In this study we analyzed the relationship between geographic distance (along the species latitudinal range) and genetic differentiation using DNA microsatellite loci developed for C. latirostris and Alligator mississippiensis. The results suggest that there is a consistent relationship between geographic distance and genetic differentiation; however, other biogeographical factors seem to be relevant. The Atlantic Chain (Serra do Mar) seems to be an effective geographic barrier, as well as the relatively narrow (< or =1.5 km) sea channel between Cardoso Island and the continent. In addition, coastal populations seem to have been well connected in recent geological time (Pleistocene 16,000 years ago) all along the eastern Brazilian coast. Further studies should focus on the S?o Francisco River drainage, which is still poorly known for this species.     

Organization of motoneurons innervating the axial musculature of the brown caiman (Caiman crocodilus fuscus)

The primary divisions of the spinal nerve in the brown caiman characteristically show the following features: (1) the medial ramus was lies in the thoraco-lumbar and caudal regions, and (2) the first cervical and hypoglossal nerves form a single nerve complex from which the ventral and dorsal rami extend. Intramuscular injections of horseradish peroxidase (HRP) established the positions of motoneurons whose axons followed the primary rami. In the ventral horn of the thoracic and caudal spinal cord, the motoneurons of the medial ramus lie ventrally. These motoneurons lie between the epaxial and hypaxial motoneurons. At the spinomedullary junction, the pools of motoneurons innervating the infrahyoid, lingual, and dorsal muscles have a somatotopic organization similar to that observed in the thoraco-lumbar and caudal regions. Thus clear somatotopic organization of the motoneurons that innervate the axial musculature exists at all spinal levels. © 1994 Wiley-Liss, Inc.     

Osmoregulation by the broad-snouted caiman, Caiman latirostris, in estuarine habitat in southern Brazil

The broad-snouted caiman Caiman latirostris, of South America mostly frequents freshwater but occurs also in estuaries. Nothing of substance is known of its osmoregulatory physiology but, in the light of accumulating evidence that alligatorids lack specialised adaptations for life in hyperosmotic waters, we anticipated its physiology would be more similar to that of Alligator mississippiensis than the euryhaline Crocodylus porosus, which has both lingual salt glands and a more complex renal:cloacal system. This proved to be the case. Caiman captured in estuaries of the Ilha do Cardoso in southern Brazil were effective hypo-osmotic osmoregulators in salinities of 0–24 ppt (seawater = 35 ppt). Plasma osmolarity, sodium and chloride were similar to those in other crocodilians and not influenced by salinity. Plasma urea was low and did not vary with salinity. We found no evidence of lingual or other salt glands. Urinary electrolyte concentrations varied considerably with salinity and in ways reminiscent of A. mississippiensis but very different from C. porosus. Ca. latirostris dehydrated in seawater more rapidly than C. porosus and had substantially higher integumental permeability to water. Caiman did not drink seawater but rehydrated rapidly when returned to freshwater (FW). We found small caiman (<500 g) only in very low salinities (<3 ppt) and larger caiman closer to the sea. We postulate that medium to large Ca. latirostris can take advantage of the feeding opportunities presented by the estuarine mangal despite lacking the physiological specialisations of crocodylids. Two individuals which we re-sighted by chance had travelled at least 600 m in 2–3 days, showing that every caiman we captured or saw was within easy reach of FW. Most likely their habitation of the estuary and its mangal is achieved through a combination of low surface area:volume ratio, relatively impermeable skin, and periodic access to FW. Accepted: 11 May 1998     

Effects of temperature on the properties of primary auditory fibres of the spectacled caiman,Caiman crocodilus (L.)

Summary The effect of temperature on the response properties of primary auditory fibres in caiman was studied. The head temperature was varied over the range of 10–35 ° C while the body was kept at a standard temperature of 27 °C (T_s). The temperature effects observed on auditory afferents were fully reversible. Below 11 °C the neural firing ceased.The mean spontaneous firing rate increased nearly linearly with temperature. The slopes in different fibres ranged from 0.2–3.5 imp s^–1 °C^–1. A bimodal distribution of mean spontaneous firing rate was found (<20 imp s^–1 and >20 imp s^–1 at T_s) at all temperatures.The frequency-intensity response area of the primary fibres shifted uniformly with temperature. The characteristic frequency (CF) increased nearly linearly with temperature. The slopes in different fibres ranged from 3–90 Hz °C^–1. Expressed in octaves the CF-change varied in each fibre from about O.14oct °C^–1 at 15 °C to about 0.06 oct °C^–1 at 30 °C, irrespective of the fibre's CF at T_s. Thresholds were lowest near T_s. Below T_s the thresholds decreased on average by 2dB°C^–1, above T_s the thresholds rose rapidly with temperature. The sharpness of tuning (Q_10db) showed no major change in the temperature range tested.Comparison of these findings with those from other lower vertebrates and from mammals shows that only mammalian auditory afferents do not shift their CF with temperature, suggesting that a fundamental difference in mammalian and submammalian tuning mechanisms exists. This does not necessarily imply that there is a single unifying tuning mechanism for all mammals and another one for non-mammals.Abbreviations BF best frequency: frequency of maximal response at an intensity 10 dB above the CF-threshold - CF characteristic frequency - FTC frequency threshold curve, tuning curve - T _s standard temperature of 27 °C     

Spatial and Temporal Variation in Reproduction of a Generalist Crocodilian,Caiman crocodilus yacare,in a Seasonally Flooded Wetland

We monitored the number of caiman (Caiman crocodilus yacare) nests in two ranches in the Brazilian Pantanal that cover an area of about 50.000 ha for 28 years (1987–2014). The number of nests was related to combinations of rainfall, water level, and number of days with temperature below 20°C, depending on the area. Most of the variation in number of nests could not be predicted by the environmental variables, but could be represented mathematically by a sine wave. We were not able to identify any external driver and suspect that the regular fluctuations may have resulted from an intrinsic population process. Presently, ranches are used as management units under the legislation for ranching Pantanal caimans. However, although some breeding females were recaptured in the area after periods of up to 21 years, most were not recaptured near nests or in general surveys of the area, suggesting that females are not strongly philopatric and that ranches do not represent isolated demographic units.     

The mitochondrial genomes of the iguana (Iguana iguana) and the caiman (Caiman crocodylus): implications for amniote phylogeny

The complete mitochondrial genomes of two reptiles, the common iguana (Iguana iguana) and the caiman (Caiman crocodylus), were sequenced in order to investigate phylogenetic questions of tetrapod evolution. The addition of the two species allows analysis of reptilian relationships using data sets other than those including only fast-evolving species. The crocodilian mitochondrial genomes seem to have evolved generally at a higher rate than those of other vertebrates. Phylogenetic analyses of 2889 amino-acid sites from 35 mitochondrial genomes supported the bird-crocodile relationship, lending no support to the Haematotherma hypothesis (with birds and mammals representing sister groups). The analyses corroborated the view that turtles are at the base of the bird-crocodile branch. This position of the turtles makes Diapsida paraphyletic. The origin of the squamates was estimated at 294 million years (Myr) ago and that of the turtles at 278 Myr ago. Phylogenetic analysis of mammalian relationships using the additional outgroups corroborated the Marsupionta hypothesis, which joins the monotremes and the marsupials to the exclusion of the eutherians.     

Regulation of ventilation in the caiman (Caiman latirostris): effects of inspired CO2 on pulmonary and upper airway chemoreceptors

In order to study the relative roles of receptors in the upper airways, lungs and systemic circulation in modulating the ventilatory response of caiman (Caiman latirostris) to inhaled CO₂, gas mixtures of varying concentrations of CO₂ were administered to animals breathing through an intact respiratory system, via a tracheal cannula by-passing the upper airways (before and after vagotomy), or via a cannula delivering gas to the upper airways alone. While increasing levels of hypercarbia led to a progressive increase in tidal volume in animals with intact respiratory systems (Series I), breathing frequency did not change until the CO₂ level reached 7%, at which time it decreased. Despite this, at the higher levels of hypercarbia, the net effect was a large and progressive increase in total ventilation. There were no associated changes in heart rate or arterial blood pressure. On return to air, there was an immediate change in breathing pattern; breathing frequency increased above air-breathing values, roughly to the same maximum level regardless of the level of CO₂ the animal had been previously breathing, and tidal volume returned rapidly toward resting (baseline) values. Total ventilation slowly returned to air breathing values. Administration of CO₂ via different routes indicated that inhaled CO₂ acted at both upper airway and pulmonary CO₂-sensitive receptors to modify breathing pattern without inhibiting breathing overall. Our data suggest that in caiman, high levels of inspired CO₂ promote slow, deep breathing. This will decrease dead-space ventilation and may reduce stratification in the saccular portions of the lung.     

Activity of tabanids (Insecta: Diptera: Tabanidae) attacking the reptiles Caiman crocodilus (Linn.) (Alligatoridae) and Eunectes murinus (Linn.) (Boidae), in the central Amazon, Brazil

Tabanid females are better known as hematophagous on man and other mammals, and linked to mechanical transmission of parasites. The association between tabanids and reptiles is poorly known, but has been gaining more corroboration through experiments and occasional observation in the tropics. The present study was conducted at a military base (CIGS/BI-2), situated 54 km from Manaus, Amazonas, in a small stream in a clearing (02 degrees 45'33"S; 59 degrees 51'03"W). Observations were made monthly, from April 1997 to March 1998, during two consecutive days. At the same time, other vertebrate animals were offered, including humans. However in this paper only data obtained on a common caiman, Caiman crocodilus (Linn.), and an anaconda, Eunectes murinus (Linn.), in diurnal observations from 05:30 a.m. to 18:30 p.m., will be discussed. A total of 254 tabanid specimens were collected, 40 from the anaconda and 214 from the caiman. Four tabanid species were recorded on these two reptiles: Stenotabanus cretatus Fairchild, S. bequaerti Rafael et al., Phaeotabanus nigriflavus (Kr?ber) and Tabanus occidentalis Linn. Diurnal activities showed species-specific patterns. The first three species occurred only in the dry season. T. occidentalis occurred during the whole observation period, and with increased frequency at the end of the dry season. We observed preferences for body area and related behavior of the host. Observations on the attack of tabanids on one dead caiman are also presented.     

Caiman latirostris (broad-snouted caiman) as a sentinel organism for genotoxic monitoring: basal values determination of micronucleus and comet assay.

Caiman latirostris is one of the two crocodilian species that inhabit Argentina. In this country, as a consequence of agricultural frontiers expansion during the last years, many areas of the geographic distribution of the broad snouted caiman overlap with regions of intensive agricultural activity. Contaminants released to the environment may induce genetic alterations in wildlife, which could lead to mutations and/or carcinogenesis. Up to the moment, no studies had been made concerning the possibbility to apply biomarkers of genotoxic evaluation in C. latirostris. The aim of this study was to adapt two widely used genotoxic techniques, the comet assay and the micronucleus test, for their application in C. latirostris and to determine the baseline values in this species, in order to establish its suitability as a sentinel organism for future genotoxic monitoring of environmental pollutants. A total of 41 juvenile caimans of 4 months old (FMO) and 10 months old (TMO) were used. Genotoxic techniques were applied on peripheral blood erythrocytes introducing the necessary modifications required by the material, which are presented here. Our results show that baseline values of DNA damage are quite stable among juvenile caimans (MN: FMO animals 0.87+/-0.74 and TMO animals 1.04+/-0.92; DI: FMO animals 103.40+/-3.36 and TMO animals 120.08+/-11.33), being independent of the nest of origin, sex and size of the animals and confirm the potential value of both short term tests as accurate screening tools for the evaluation of genotoxic agents in C. latirostris. This is the first reference to the application of genotoxic techniques on C. latirostris and the second in crocodilians. Data provided here will be useful for future studies involving the biomonitoring of natural regions where C. latirostris occurs, employing this species as a sentinel organism for genotoxic assessment of environmental pollutants.     

Protein degradation in aged nematodes (Turbatrix aceti).

The rates of degradation of total soluble proteins in the free-living nematode, $\text{Turbatrix aceti}$, have been estimated by following the loss of acid-insoluble insoluble radioactivity from protein during a nonradioactive chase period after initial labeling with [³⁵S]methionine. These proteins appear to lose label kinetically as a homogeneous class in age-synchronized nematode populations. However, proteins are degraded more slowly in senescent cultures than in young cultures. Protein degradation rates decline progressively during nematode aging. These findings suggest that the protein degradative system in T. aceti may become partially defective with advancing age which may result in the accumulation of aberrant protein molecules in senescent organisms.