Leishmania adleri: in vitro phagocytosis by lizard leukocytes and peritoneal exudate cells

The interaction of iguanid lizard (Dipsosaurus dorsalis) blood cells and promastigote forms of Leishmania adleri Heisch 1954 was observed in vitro by means of wet mount preparations. Some parasites were phagocytized within a short time after their addition to the preparations. Parasites were engaged and engulfed either individually or in masses. Rapid decrease in size of the parasites occurred. The process of phagocytosis of the parasites was found to be very similar to that of mammalian leishmanias in similar preparations with mammalian cells. Cell cultures prepared from peritoneal exudates of lizards (Basiliscus vittatus) were inoculated with L. adleri promastigotes. Resultant intracellular amastigotes were observed up to 36 hr at 25 and 35 C.     

Interspecific interactions tested: two species of malarial parasite in a West African lizard

Plasmodium giganteum and P. agamae, parasites of the rainbow lizard, Agama agama, in West Africa were studied to determine the nature of any interspecific interactions between the two malaria species. The plasmodia are distributed in A. agama throughout the mesic zone of Africa; P. agamae is sometimes found as a solitary malaria species in populations of the lizard, but P. gigateum has not been found alone. In 3170 lizards from Sierra Leone the prevalence of lizard malaria at 22 sites varied considerably (8–90% of lizards were infected), but the ratio of the two species was similar among sites (52–91% P. agamae). Larger lizards were more often infected. Mixed infections occurred 2–5 times more often than expected by chance. Parasite density within individual hosts, or parasitemia, was similar for each species when alone or in mixed infection. Natural infections followed in laboratory lizards stayed at constant levels for as long as 211 days. The two species use different classes of host cells (P. giganteum in immature cells and P. agamae in mature erythrocytes) and may have different periods of peak transmission. Analysis of the data does not support a neutral relationship between P. giganteum and P. agamae, nor ongoing competition for resources or heterologous immunity. The data best support facilitation in which P. agamae alters the host in a way that allows more successful establishment of P. giganteum.     

The effects of progesterone on sexual behavior in male green anole lizards (Anolis carolinensis)

It is well known that androgen-dependent sexual behaviors in male mammals and birds are inhibited by exogenous progesterone (P). However, recent research on male whiptail lizards (Cnemidophorus inornatus) indicates that P can stimulate sexual and copulatory behavior. We report here both antiandrogenic and synandrogenic actions of P on sexual behavior in males of another reptile, the green anole lizard (Anolis carolinensis). Earlier reports on birds and mammals are reviewed and discussed in relation to a possible physiological role of P in influencing sexual behavior in male vertebrates.     

Observations on the epidermis of desert-living iguanids

The epidermis of 146 specimens of Dipsosaurus dorsalis and 182 Uma notata collected throughout the active period of the animals' year has been examined. The morphology of the epidermis is essentially similar to previously described lacertilians but differs in the relatively great degree of development of the mesos layer and the complete keratinization of the lacunar tissue prior to sloughing. Analysis of sloughing frequency throughout the year suggests that species specific patterns may exist, but these do not correlate with any particular known ecologic datum. The patterns do not reflect the reproductive activity of the two species supporting previous experimental conclusions on the lack of effect of gonadial hormones on epidermal activity. There appears to be no evidence of association of femoral gland activity with epidermal activity in D. dorsalis, but the situation is not clearcut in U. notata. These data are discussed in the light of recent studies of the evolutionary origin of epidermal glands in lizards.     

Plasma lipid concentrations for some Brazilian lizards.

1. Plasma concentrations of cholesterol, cholesteryl esters, phospholipids and triglycerides were determined for ten species of Brazilian lizards, Iguana iguana, Tropidurus torquatos and T. semitaeniatus (Iguanidae), Tupinambis teguixin, Ameiva ameiva and Cnemidophorus ocellifer (Teiidae), Mabuya maculata (Scincidae), Hemidactylus mabouia (Gekkonidae), Amphisbaenia vermicularis and Leposternon polystegum (Amphisbaenidae). 2. Considerable inter- and intra-species variations in plasma lipid concentrations were observed. 3. The percentage of total cholesterol esterified and the individual phospholipid composition of plasma were relatively constant for each species. 4. Over 60% of the cholesteryl esters present in plasma from three species each of iguanid and teiid lizards were polyenoic.     

Leishmania tarentolae: Utility as an in vitro model for screening of antileishmanial agents

Primary screens for antileishmanial compounds use Leishmania species pathogenic to humans that must be handled under biosafety conditions that cannot be adopted or guaranteed everywhere. Leishmania tarentolae, a parasite isolated from the gecko Tarentolae annularis, has not been considered pathogenic to humans. Promastigotes of L. tarentolae have been previously used as a eukaryotic expression system for the production of recombinant proteins and in the amplification of genes involved in resistance to antileishmanial drugs. To validate the use of this Leishmania species in the screening of antileishmanial drugs, the sensitivity of axenic and intracellular amastigotes of L. tarentolae was compared to the sensitivity showed by Leishmania species causative of human leishmaniasis. The ability of L. tarentolae to grow as axenic amastigotes is first described while its ability to infect several mammalian cells has been confirmed. L. tarentolae amastigotes offer a suitable model for the in vitro screening of compounds for antileishmanial activity.     

Temperature effects on ACTH-stimulated adrenocortical secretion and carbohydrate metabolism in the lizard (Dipsosaurus dorsalis)

Summary Desert iguanas (Dipsosaurus dorsalis) were maintained at 10, 20, 30 or 40°C for one week. Animals were autopsied at zero time, and 30 and 90 minutes after a single injection of ACTH. Basal plasma corticosterone (B) level was similar in all lizards regardless of environmental temperature. Both blood glucose and liver glycogen levels showed highly significant correlations with environmental temperature. Injection of ACTH increased plasma B level in all temperature groups but the rate and magnitude of the response were temperature dependent. Liver glycogen was increased after ACTH injection at 20°C and plasma glucose response to ACTH was significantly correlated with temperature.     

Salt excretion in a beach lizard (Ameiva quadrilineata, Teiidae)

Summary The teiid lizardAmeiva quadrilineata has a nasal salt gland that responds to NaCl loading by increasing excretion of Na⁺ (from 1.12 to 2.63 M/100 gh), K⁺ (from 0.14 to 2.43 M/100 gh), and Cl^– (from 1.10 to 5.47 M/100 gh). For salt-loaded lizards these values represent 47% of the total excretion of Na⁺, 35% for K⁺, and 87% for Cl^–.The lizards forage on beaches and their diet includes large numbers of amphipods (Talorchestia) which are approximately twice as salty as the lizards' body fluids. All of the ingested Na⁺ and K⁺ can be excreted through the cloaca, but extra-renal excretion of Cl^– is probably important to the lizards under natural conditions.     

Phylogenetic relationships of corytophanid lizards (Iguania, Squamata, Reptilia) based on partitioned and total evidence analyses of sperm morphology, gross morphology, and DNA data

We conducted partitioned and combined Bayesian and parsimony phylogenetic analyses of corytophanid lizards (Iguania) using mtDNA, gross morphology, and sperm ultrastructure data sets. Bayesian and parsimony hypotheses showed little disagreement. The combined analysis, but not any of the partitioned ones, showed strong support for the monophyly of Corytophanidae and its three genera, Basiliscus , Corytophanes , and Laemanctus . Basiliscus is the sister taxon of a well-supported clade formed by Corytophanes and Laemanctus . The relationships of species within Basiliscus and Corytophanes received weak support, regardless of the method used. We defend those relationships as feasible and open to further testing. Data derived from the ultrastructure of spermatozoa are potentially a good source of characters for systematic inferences of Iguania and its major lineages. A Brooks Parsimony Analysis based on the geographic distributions of corytophanids and the phylogenetic tree obtained from the combined analysis suggested a Central American origin of the group, a recent colonization of northern South America, and the role of epeirogenic uplifts and the formation of lowlands during the late Tertiary in the differentiation of corytophanids.     

Temperature and metabolism in Leishmania. 3. Some dehydrogenases of L. donovani, L. mexicana, and L. tarentolae

The effects of temperature on four dehydrogenases in homogenates of promastigotes of Leishmania donovani (several strains), L. mexicana, and L. tarentolae were studied.     

The distribution, density and biomass of terrestrial reptiles in Dominica, West Indies

Fourteen species of reptiles have been recorded from the island of Dominica, Lesser Antilles. As part of a larger study of the ecology of Dominica's forests, the distribution, density and biomass of three widespread lizard species ( Anolis oculatus, Ameiva fuscata and Mabuya mabouya ) were estimated in all major vegetation types. No consistent differences between seasons occurred for any of the three species, and at no site was a definite breeding season detected. Densities, estimated mainly by plot counts, were highest in coastal woodlands where mean densities reached 2148 Anolis per hectare, 379 Ameiva per hectare, and 751 Mabuya per hectare. Densities in rain forest sites were often very low. Combined biomass for the three species also reached a maximum in coastal woodlands of 44.7 kg/ha. This value is amongst the highest recorded for terrestrial reptile assemblages, and suggests that Dominica's coastal woodlands are unusually favourable habitats for reptiles.
Previous studies of Caribbean lizards have suggested that either competition or predation from birds may influence lizard densities. The present study, however, found no such relationships, and it was concluded that lizard density was independent of bird density.     

Leishmania tarentolae and Leishmania infantum in humans,dogs and cats in the Pelagie archipelago,southern Italy

Visceral leishmaniasis (VL) caused by Leishmania infantum is endemic in the Mediterranean basin with most of the infected human patients remaining asymptomatic. Recently, the saurian-associated Leishmania tarentolae was detected in human blood donors and in sheltered dogs. The circulation of L. infantum and L. tarentolae was investigated in humans, dogs and cats living in the Pelagie islands (Sicily, Italy) by multiple serological and molecular testing. Human serum samples (n = 346) were tested to assess the exposure to L. infantum by immunofluorescence antibody test (IFAT), enzyme-linked immunosorbent assay (ELISA) and Western blot (WB) and to L. tarentolae by IFAT. Meanwhile, sera from dogs (n = 149) and cats (n = 32) were tested for both Leishmania species by IFAT and all blood samples, including those of humans, by specific sets of real time-PCR for L. infantum and L. tarentolae. The agreement between serological tests performed for human samples, and between serological and molecular diagnostic techniques for both human and animal samples were also assessed.Overall, 41 human samples (11.8%, 95% CI: 8.9–15.7) were positive to L. infantum (5.2%, 95% CI: 3.3–8.1), L. tarentolae (5.2%, 95% CI: 3.3–8.1) and to both species (1.4%, 95% CI: 0.6–3.3) by serology and/or molecular tests. A good agreement among the serological tests was determined. Both Leishmania spp. were serologically and/or molecularly detected in 39.6% dogs and 43.7% cats. In addition to L. infantum, also L. tarentolae circulates in human and animal populations, raising relevant public health implications. Further studies should investigate the potential beneficial effects of L. tarentolae in the protection against L. infantum infection.     

Chemosensory Response of Desert Iguanas (Dipsosaurus dorsalis) to Skin Lipids from A Lizard-Eating Snake (Lampropeltis getula californiae)

Several species of lizards respond to chemicals from sympatric lizard‐eating snakes with increased tongue‐extrusion rates. These substances also elicit antipredator behavior indicating that they have important ecological functions and the resulting behavior can have serious implications for individual fitness of lizards. However, the source and type of snake chemical cues that elicit these behavioral changes in lizards have yet to be determined. We tested the ability of adult desert iguanas (Dipsosaurus dorsalis) to detect and identify a potential predator by exposing them to lipids extracted from shed snakeskins. Lipids were extracted from cast skins of a known lizard‐eating snake, the California kingsnake (Lampropeltis getula californiae), using chloroform and methanol. Test subjects were presented with skin lipids as well as clean, pungent, and chloroform controls on cotton‐tipped applicators in random order. Desert iguanas directed significantly more tongue extrusions toward applicators bearing snakeskin lipids when compared with controls. In addition, overall tongue‐extrusion frequency increased following exposure to lipids during the 5‐min trials. Desert iguanas clearly detected snakeskin lipids, but this stimulus failed to elicit changes in body posture and movement patterns previously observed in experiments using chemical cues from live snakes. Increased tongue flicking by lizards in response to snakeskin lipids may represent a generalized response to this class of chemicals. Additional potential sources of chemicals used in the detection of lizard‐eating snakes are discussed.     

Circadian locomotor rhythms in the desert iguana

Summary Desert iguanas, Dipsosaurus dorsalis, displaying freerunning circadian locomotor rhythms in conditions of constant darkness and temperature received electrolytic lesions to the hypothalamus. The locomotor activity of those lizards (N = 9) which sustained 80% or more damage to the suprachiasmatic nucleus (SCN) became arrhythmic whereas all animals that sustained less than 35% damage to the SCN remained rhythmic, even though they sustained significant damage to nearby regions of the hypothalamus and preoptic area. These results suggest strongly that the SCN plays a role in the regulation of circadian rhythms in the desert iguana. Taken together with other evidence, they support the view that this structure is homologous to the mammalian SCN, which acts as a pacemaker in the circadian system.Abbreviations SCN suprachiasmatic nucleus - freerunning circadian period     

Cloning,characterization and preliminary crystallographic analysis of Leishmania hypoxanthine–guanine phosphoribosyltransferase

Hypoxanthine–guanine phosphoribosyltransferase (HGPRT) (EC 2.4.2.8) is an important enzyme involved in the recycling of purine nucleotides in all cells. Parasitic protozoa of the order Kinetoplastida are unable to synthesize purines de novo and use the salvage pathway for the synthesis of nucleotides; therefore, this pathway is an attractive target for antiparasitic drug design. The hgprt gene was cloned from a Leishmania tarentolae genomic library and the sequence determined. The L. tarentolae hgprt gene contains a 633-nucleotide open reading frame that encodes a 23.4-kDa protein. A pairwise alignment of the different HGPRT's sequences revealed a 26%–53% sequence identity with the Leishmania sequences and 87% identity to the HGPRT of Leishmania donovani. A recombinant protein was expressed in Escherichia coli, purified to homogeneity and found to retain enzymatic activity. The steady-state kinetic parameters were determined for the recombinant enzyme and the enzyme is active as a homodimer in solution. Single crystals were obtained for the L. tarentolae HGPRT representing the first Leishmania HGPRT crystallized and initial crystallographic data were collected. The crystals obtained belong to the orthorhombic space group (P2₁2₁2₁) with unit cell parameters a=58.104 Å, b=85.443 Å and c=87.598 Å and diffract to a resolution of 2.3 Å. The availability of the HGPRT enzyme from Leishmania and its crystallization suitable for X-ray diffraction data collection should provide the basis for a functional and structural analysis of this enzyme, which has been proposed as a potential target for rational drug design, in a Leishmania model system.     

Banding patterns and chromosomal evolution in five species of neotropical Teiinae lizards (Squamata: Teiidae)

Karyotypes of five species of South American teiid lizards from subfamily Teiinae: Ameiva ameiva, Kentropyx calcarata, K. paulensis, K. vanzoi (2n = 50, all acrocentric), and Cnemidophorus ocellifer (2n = 50, all biarmed), are herein described and compared on the basis of conventional and silver staining, and CBG and RBG banding patterns. Meiotic data are also included. Karyotypes of K. paulensis, K. vanzoi, and C. ocellifer are reported here for the first time. Inter-generic variability in Ag-NORs location was detected with NORs occurring at the end of long arm of pair 1 in K. calcarata, K. paulensis, and K. vanzoi; pair 5 in C. ocellifer and pair 7 in A. ameiva. The location of NORs, along with the karyological differences between A. ameiva and the Central American species (A. auberi), corroboretes the molecular-based hypothesis that the genus Ameiva is paraphyletic. Inter-populational heteromorphism in Ag-NORs size was detected between populations of C. ocellifer. RBG and CBG banding data demonstrated that the biarmed condition of the C. ocellifer chromosomes is due to multiple pericentric inversion events instead of addition of constitutive heterochromatin. Differential-staining techniques used here revealed valuable information about Teiinae karyotypic diversity and made it possible to compare these species, contributing to both the better comprehension of their chromosomal evolution and issues on taxa systematics.     

Phylogeographic histories of representative herpetofauna of the southwestern U.S.: mitochondrial DNA variation in the desert iguana (Dipsosaurus dorsalis) and the chuckwalla (Sauromalus obesus)

To determine whether genetic variation in representative reptiles of the southwestern U.S. may have been similarly molded by the geologic history of the lower Colorado River, we examined restriction site polymorphisms in the mitochondrial DNA (mtDNA) of desert iguanas (Dipsosaurus dorsalis) and chuckwallas (Sauromalus obesus). Observed phylogeographic structure in these lizards was compared to that reported for the desert tortoise (Xerobates agassizi), whose mtDNA phylogeny demonstrates a striking genetic break at the Colorado River. Both the desert iguana and chuckwalla exhibit extensive mtDNA polymorphism, with respective genotypic diversities G = 0.963 and 0.983, close to the maximum possible value of 1.0. Individual mtDNA clones, as well as clonal assemblages defined by specific levels of genetic divergence, showed pronounced geographic localization. Nonetheless, for each species the distributions of certain clones and most major clonal groupings encompass both sides of the Colorado River valley, and hence are clearly incongruent with the phylogeographic pattern of the desert tortoise. Overall, available molecular evidence provides no indication that the intraspecific phylogenies of the southwestern U.S. herpetofauna have been concordantly shaped by a singular vicariant factor of overriding significance.     

Diversity and Distributional Patterns of Neotropical Freshwater Copepods (Calanoida: Diaptomidae)

The distributional patterns and diversity of the diaptomid calanoid copepods were analysed to assess the faunistic affinity of North and South America with respect to Mexico and Central America. In the Neotropical region, the most speciose genera of Diaptomidae are Leptodiaptomus and Mastigodiaptomus. The former genus is a Nearctic form, and Mastigodiaptomus is Neotropical. Based on the current distribution of their diversity, it is probable that these genera radiated into Mexico and Central America from North America and the insular Caribbean, respectively. Arctodiaptomus dorsalis is a primarily Palaearctic taxon, it is widely distributed between North and Central America. This species probably radiated in the Americas as a Tethyan derivate. Prionodiaptomus is the only member of the highly diverse South American diaptomid fauna that has expanded beyond the subcontinent. Despite the high diversity present in South America, its influence in Mexico and Central America appears to be weak; this is probably a consequence of the geologically recent union of the two main subcontinental landmasses. Mexico shares 33% of its species with NA, and no species are shared between NA and SA. For the Diaptomidae, the Nearctic influence is strongest in Mexico. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Thermal ecology of five Cnemidophorus species (Squamata: Teiidae) in east coast of Brazil

In this study we compared the body temperature of 16 populations belonging to five species of the genus Cnemidophorus from restinga habitats along the eastern coast of Brazil in order to evaluate the importance of how some environmental factors affect lizard body temperatures. Cloacal body temperatures (T_b) were taken immediately after capture with a quick-reading thermometer (Schultheis). Substrate temperatures (T_s) and air temperatures (T_a; approximately 1 cm above the substrate) were taken as close as possible to the point when each lizard was initially sighted. Most of the mean body temperatures in activity of the different populations and species of Cnemidophorus along the coast of Brazil ranged from 36.5 to 39.3 °C, except for Cnemidophorus lacertoides (T_b=35.2 °C) in the restinga of Joaquina, SC and for Cnemidophorus ocellifer (T_b=34.8 °C ) in the restinga of Praia do Porto, SE. Some studies show that the body temperature of lizards is more related to phylogenetic than ecological factors, suggesting that species of the same genus tend to have similar body temperatures even occurring in different types of environments. In general, regardless of the locality and latitude along the eastern coast of Brazil, the different species of lizards of the genus Cnemidophorus and their respective populations have similar body temperatures in activity and the apparent differences result from the influence of the local thermal environment of each restinga.     

Additional notes on requirements of captive whiptail lizards (Cnemidophorus), with emphasis on ultraviolet radiation

Since 1972 we have maintained a colony of parthenogenetic Cnemidophorus exsanguis, which has reached the seventh generation in our laboratory. This paper reports improved husbandry techniques that allow maintenance of healthy, reproducing colonies of this and additional species of Cnemidophorus. In addition, aspects of the physiology of calcium regulation and metabolic bone disease are discussed in relation to the captive rearing of lizards through many generations.