Chaetophractus Villosus Research Articles

Comparative vertebrate fibrinolysis

Fibrinolysis is a feature in the phylogeny of vertebrates. This review analyzes the fibrinolytic mechanism in different species compared to healthy adult humans. Additionally, it introduces the armadillo Chaetophractus villosus (Mammalia, Xenarthra, Dasypodidae) whose lytic process remains quite unknown until now. The analysis was conducted in a phylogenetic order: fish, amphibians, reptiles, birds, and mammals. It was designed to assess the fibrinolytic system in its various stages: global, specific, and degradation. The results are represented in tables grouped by test: fibrinogen, whole blood lysis time, whole blood diluted lysis time, euglobulin lysis time, plasminogen, fibrin/fibrinogen degradation products, D dimer, plasminogen activator inhibitor type 1, and alpha 2 antiplasmin activity. Global knowledge of the mechanism of fibrinolysis in vertebrates is a contribution of scientific interest not only in biology, but also for the development of experimental models applicable to the study of thrombotic and thrombolytic agents.

Eto-Ecología y Conservatión de Tres Especies de Armadillos (Dasypus hybridus, Chaetophractus villosusyC. vellerosus) en el Noreste de la Provincia de Buenos Aires, Argentina

Abstract A capture-recapture study was performed to obtain data on abundance of three armadillo species inhabiting a highly modified habitat—the Argentinean pampas—and the intrinsic factors affecting this parameter. A total of 144 live armadillos (42 Dasypus hybridus, 15 Chaetophractus villosus and 87 C. vellerosus) were caught and 49 dead animals (30 D. hybridus, 15 C. villosus and 4 C. vellerosus) were collected on four farms subjected to different degrees of land use. Armadillos were negatively affected by habitat use and hunting pressure. Densities varied between 0.07 and 0.6 armadillos per hectare, with higher densities occurring on farms farther away from urban settlements, with few domestic dogs, low hunting pressure, conservative land use, and well-preserved natural grasslands. The results suggest the existence of source-sink metapopulations.

Osteoderm morphology in recent and fossil euphractine xenarthrans

AbstractThe presence of osteoderms within the integument, forming a carapace, is one of the most distinctive features of armadillos with the external morphology of these elements forming the basis of most systematic schemes. This is especially true for fossil taxa, where these elements are most frequent in the palaeontological record. A detailed study of osteoderms from the cephalic shield and different regions of the dorsal armour of Chaetophractus villosus (Euphractinae, Xenarthra) was made and compared to those of the extant genus Dasypus (Dasypodinae, Xenarthra), and the extinct genus †Eutatus. Three distinct histological zones were recognized: outer and inner zones are thin, formed by regular compact bone, the middle zone is thicker, with large cavities that contain mainly adipose tissue, hair follicles, and sweat and sebaceous glands. The internal structure of †Eutatus (also a member of Euphractinae) osteoderms is close to that of C. villosus, consistent with the notion that these taxa are phylogenetically closely related. In contrast, Dasypus shows marked differences. Dasypus shows hair follicles associated with both gland types (sweat and sebaceous) and connected to foramina on the external surface. Although not observed in adult C. villosus, it has been documented during embryonic development, only to atrophy later in ontogeny. Furthermore, the presence of red bone marrow is rare in C. villosus, but widespread in Dasypus novemcinctus osteoderms. These results suggest an early split of both subfamilies and support the hypothesis that the Euphractinae are more derived than the Dasypodinae.

The species of Eutatus (Mammalia, Xenarthra): Assessment, morphology and climate

From a systematic perspective, the genus Eutatus is in a complex situation. P. Gervais published the type species, Eutatus seguini. Later, F. Ameghino recognized Eutatus brevis, Eutatus punctatus and Eutatus minutus, whose diagnostic characters were not clearly defined. A.F. Bordas added a new species, Eutatus ameghinoi, and provided anatomical differences between this species and E. seguini, but did not compare it with the others previously recognized by Ameghino. For these reasons, Scillato-Yané only recognized for the Ensenadan, Bonaerian and Lujanian stages the type species E. seguini and synonymized the other four. On the other hand, E. seguini has been mentioned as occurring, if not exclusively, in the Ensenadan stage. However, an exhaustive review of earlier publications indicates that E. seguini is the Eutatus species occurring in the Bonaerian, Lujanian and Platan (middle Pleistocene to early Holocene) stages. Osteoderm characters, as well as endoskeletal elements, were compared between specimens assigned to the previously nominated species. A detailed analysis of osteoderms from homologous regions of the pelvic shield (internal and external morphology) was performed to identify significant differences that would allow recognition of the eventual species of this genus. Materials from the Chapadmalalan, Marplatan (Vorohuean), Ensenadan and Lujanian stages were selected. An equivalent comparative study was made on the osteoderms of Chaetophractus villosus (Euphractinae, Euphractini) to assess the range of intraspecific morphological variations. Differences were found between osteoderms from different stratigraphical provenance. According to the new nomenclatural situation proposed here, E. seguini is limited to the Bonaerian, Lujanian and Platan stages, and a new species is recognized for the Marplatan (Vorohuean, Sanandresian) and Ensenadan stages. The morphological changes in osteoderms of different Eutatus species may be correlated with paleoclimate variations, because these changes consist of variations in the amount and extension of cavities that would have held hair follicles and the development of cavities that would have been filled with adipose tissue, probably acting as thermal insulation.

Sexual dimorphism in the mandible of the armadillo Chaetophractus villosus (Desmarest, 1804) (Dasypodidae) from northern Patagonia, Argentina

The aim of this study was to study the sexual dimorphism in adult Chaetophractus villosus (Desmarest, 1804), from northern Patagonia, Argentina. Eight mandibular traits were measured in 37 males and 34 females. Univariate and multivariate morphometric analysis were applied to the data set. Results showed that C. villosus was sexually dimorphic, with higher absolute values corresponding to females. The total length of the mandible was the most important variable to discriminate sexes, followed by the height at the level of the last tooth and body length. The percentages of sex discrimination were high, as they were when a new sample (17 males, 13 females) was tested. Females have larger mandibles than males independently of their larger cranial size. They also showed a higher degree of correlation between variables, suggesting a more stable shape for the mandible than in males.

Fibrinolytic system of the armadillo Chaetophractus villosus (Xenarthra, Dasypodidae)

The fibrinolytic mechanism in the armadillo Chaetophractus villosus (Mammalia, Xenarthra, Dasypodidae) quite unknown until now was studied. Results were compared with those corresponding to healthy adult human beings. Whole blood lysis time and diluted blood lysis time were not detectable in armadillos. Euglobulin clot lysis time and plasminogen activity (Plg) were lower than in healthy humans. We established the presence of the fibrinolytic system in Ch. villosus through the measurement of fibrin fibrinogen degradation products. The activity of the plasminogen activator inhibitor was two to four times greater than in healthy humans. The activity of the alpha 2 anti-plasmin (α2AP) was similar and displaced toward lower values. The Plg/α2AP relation was lower. The results obtained suggest that Ch. villosus has a hypercoagulable and hypofibrinolytic profile. Our findings are not only the first contribution to elucidate the physiology of the fibrinolytic system in Xenarthra but also contribute to develop an animal model for studies in haemostasis and thrombosis.

Effects of Land Use on the Distribution of Three Species of Armadillos in the Argentinean Pampas

We evaluated the effects of land use on the distribution of 3 sympatric species of armadillos, Chaetophractus villosus, C. vellerosus, and Dasypus hybridus, on 34 farms in the eastern Pampas. We characterized 4 soil and vegetation variables around each burrow located during surveys of these farms, and related burrow abundance to 10 variables used to characterize each farm. C. vellerosus was the most specialized, using primarily native woodlands and areas with calcareous soil. D. hybridus was associated with natural grasslands and avoided cultivated pastures, and was negatively related to the number of dogs that lived on the farms. C. villosus, the most abundant species, was found in all 4 types of habitats, but its distribution depended on the intensity of hunting on each farm.

Structure of armadillo ACBP: a new member of the acyl-CoA-binding protein family.

The X-ray structure of the tetragonal form of apo acyl-CoA-binding protein (ACBP) from the Harderian gland of the South American armadillo Chaetophractus villosus has been solved. ACBP is a carrier for activated long-chain fatty acids and has been associated with many aspects of lipid metabolism. Its secondary structure is highly similar to that of the corresponding form of bovine ACBP and exhibits the unique flattened alpha-helical bundle (up-down-down-up) motif reported for animal, yeast and insect ACBPs. Conformational differences are located in loops and turns, although these structural differences do not suffice to account for features that could be related to the unusual biochemistry and lipid metabolism of the Harderian gland.

Principal coagulation factors and natural anticoagulants in the armadillo Chaetophractus villosus (Mammalia, Xenarthra, Dasypodidae)

Blood coagulation is an important process regulated by a large number of proteins, which transform fibrinogen into fibrin. This mechanism was identified in several species other than humans. In this work we study the coagulation factors and principal natural anticoagulants in armadillos (Chaetophractus villosus). Coagulation factors FVII, FXII, FIX, FXI, FX, FVIII, FV, antithrombin (AT), protein C (PC), and protein S (PS) were identified. The activities of all factors were homogeneous for both sexes. Correlation studies showed associations between FVII and FX, FVII and FIX, FVII and FXI, FIX and FXI, and FIX and FX. Sex-related differences were observed for PS but not for AT or PC. There was positive correlation between PS and FV in females. These data constitute the first contribution to the knowledge of the proteins participating in the coagulation in this species and they demonstrate that the hemostatic process is similar in the armadillos and man.

Haemostatic mechanisms of the armadillo Chaetophractus villosus (Xenarthra, Dasypodidae)

Haemostatic mechanisms in humans are formed by two activation pathways, named tissular factor pathway and contact system pathway, and a common pathway, that promotes the formation of the fibrin clot. These mechanisms have also been identified in other mammals. In this work we evaluate their presence in the armadillo Chaetophractus villosus, a mammal of the neotropical Xenarthra Order. Twenty animals (ten males and ten females), previously adapted to captivity, were used. Fibrinogen (Fbg) was measured at the beginning and at the end of the experimental period; prothrombin time (PT), activated partial thromboplastin time (APTT) and thrombin time (TT) were measured at the same time during the experience. Neither Fbg nor the other parameters evaluated showed sex-related differences, but Fbg diminished during the experimental period. TT related to PT and APTT showed longer times and larger dispersion of the individual values. Compared to the human beings, PT and TT were longer and APTT was shorter. Considering those results, we conclude that C. villosus has the same basic coagulation system as human beings. However, in this species the contact system pathway seems to play a greater role in the activation of the coagulation system than it does in man, and the common pathway appears to limit the velocity of the system.

Anatomy, histology, histochemistry and fine structure of the Harderian gland in the South American armadillo Chaetophractus villosus (Xenarthra, Mammalia)

The anatomical, histological, histochemical and ultrastructural characteristics of the Harderian gland of the armadillo Chaetophractus villosus were described. The gland is the largest structure in the bony orbit. It is situated in the anteroventral region of the orbit. Obvious structural differences are not observed between males and females. The gland is compound-branched tubulo-alveolar, being characterized by a single layer of columnar cells surrounded by myoepithelial cells. It possesses a single excretory duct opened into the inner canthus. All glandular cells show yellow-green autofluorescence and additionally some glandular lumen may contain dense autofluorescent solid accretions. There are two peculiar and outstanding cytoplasmic features. One is represented by the smooth endoplasmic reticulum (SER), forming a closely woven meshwork. The other one is represented by "membranous bodies" apparently derived from the SER, RER and cytoskeleton with a "Star of David" configuration situated in the supranuclear region. Three types of vesicles are detected in the cytoplasm. Histochemical staining methods reveal lipids, proteins, neutral and acidic containing glycoconjugates in secretory vesicles. The mechanism of secretion appears either merocrine or apocrine. The epithelium of the intra- and inter-lobular excretory ducts suggests secretory activity. Tubulo-acinar glands similar to those seen in the lacrimal gland and nictitans glands are found related to the intralobular and main excretory ducts. The capillary network is characterized by fenestrated endothelium. The stroma possesses unmyelinated axons and plasma cells. The normal secretion of the secretory endpieces, particularly lipids, proteins and glycoconjugates, is complemented by mucous and serous secretions released by ductal cells and glands associated to the ducts.

Morphology of female genital tracts in Dasypodidae (Xenarthra, Mammalia): a comparative survey

Previous works about comparative spermatology in Dasypodidae determined that sperm morphology is a striking variable among genera. It was suggested that this sperm feature may be related to specific morphologies of the female reproductive tract. The present comparative study of the morphology of the female genital tract from seven species corresponding to six genera of Dasypodidae is aimed to determine the main similarities and differences between the species and to establish a possible correlation with the sperm shapes and sizes. Genital tracts were studied macroscopically and histologically. Dasypus hybridus has disk-shaped ovaries and the cortex occupies almost all the organ with a single oocyte in each follicle. Tolypeutes matacus, Chaetophractus villosus, Chaetophractus vellerosus, Zaedyus pichiy, Cabassous chacoensis and Clamyphorus truncatus possess ovoid and elongated ovaries, with both longitudinally polarized cortex and medulla, and the peculiar presence of several oocytes in the same follicle. D. hybridus and T. matacus have a simple pear-shaped uterus, but in the other species the uterus is pyramid shaped and bicornuate. The uterine cervix is very long in all studied species. Only T. matacus presents a true vagina as in most eutherian mammals; on the other hand, in the other species a urogenital sinus is observed. The structure of female reproductive tracts in Dasypodidae contains a mixture of assumedly primary and other derived features. According to the different morphologies of the regions analyzed, a classification of the female genital tracts in three groups can be performed (group 1: Dasypus; group 2: Tolypeutes; group 3: Chaetophractus, Zaedyus, Cabassous, Clamyphorus) and a correlation between each group and a specific sperm morphology can be established.

A study of platelets in the armadillo chaetophractus villosus (xenarthra, dasypodidae)

Nothing is known about haemostasis in Xenarthra, a widely distributed Order of American mammalians. Chaetophractus villosus, a member of the Dasypodidae family of this group, which is easily adapted to captivity, is of growing interest for biomedical research. In this work, we studied platelet number, MPV, ultrastructure of the platelets by SEM and TEM, and aggregation responses to ADP and ristocetin in this species. Blood samples were obtained by cardiac puncture in 20 anaesthetised animals. Platelet count and MPV were evaluated at the beginning and at the end of a 3-year experimental period, to detect possible variations related to time of captivity. SEM and TEM were done by routine methods adapted to the material, and aggregation response to ADP and ristocetin were evaluated by the Born method. The parameters studied did not show any sex-related differences, nor did the platelet count change during captivity. Nevertheless, MPV decreased during this period. Platelets were ultrastructurally similar to those of other mammals and human beings and responded to proven agonists. Data provided in this study will contribute to the understanding of the haemostatic process in this species.

Burrowing owls and burrowing mammals: are ecosystem engineers interchangeable as facilitators?

Terrestrial vertebrates exhibit dynamic, positive interactions that form and dissolve under different circumstances, usually with multiple species as participants. Ecosystem engineers are important facilitators of other species because they cause physical changes in the environment that alter resource availability. Although a species can be associated with more than one partner, facilitators may not be interchangeable if they differ in abundance, behavioral characteristics, or interactions with other factors in ways that condition the outcome of the association. We examined interactions between burrowing owls (Athene cunicularia) and two burrowing mammals, hairy armadillos (Chaetophractus villosus) and plains vizcachas (Lagostomus maximus), and determined whether these ecosystem engineers are interchangeable for owls. We examined reproductive success for owls nesting in these mammal burrows, constructed a logistic regression model to identify habitat characteristics associated with owl nests, and examined the engineering activities of the mammals. Data on reproduction and habitat indicate that armadillos and vizcachas are not interchangeable for owls. Thirty‐five percent of the nests in vizcacha burrows produced fledglings; no fledglings were produced from nests outside vizcachas colonies, even though owls nest successfully in armadillo burrows in other parts of Argentina. Vizcachas facilitate burrowing owls by construction of burrows and by producing open understory vegetation through herbivory. In contrast, armadillos do not alter vegetation, and their burrows are suitable for nest sites only when they occur in recently burned areas or areas maintained by anthropogenic disturbance. Our habitat model also suggests that fire plays a key role in maintaining owl populations because fire is the only natural process that reduces shrubs to the level required by owls. Current management practices of eradication of vizcachas and fire suppression in shrublands could have strong negative consequences for burrowing owls.

Histology, Histochemistry and Fine Structure of the Lacrimal and Nictitans Gland in the South American ArmadilloChaetophractus villosus (Xenarthra, Mammalia)

The anatomical, histological, histochemical and ultrastructural characteristics of the lacrimal gland (LG) and nictitans gland (NG) of the armadillo Chaetophractus villosus were described. The histochemical and histological features of both glands in male and female adult animals were compared. The tissues were processed with conventional techniques for light and transmission electron microscopy. Fixed specimens were submitted to a battery of tests for glycans, glycosaminglycans, glycoconjugates, proteins, and lipids. The LG of the armadillo may be considered within the set ofglandulae lacrimales superior in which primates, carnivores, perisodactyls and artiodactyls are included. The localization of the NG was similar to that of other mammals. Lacrimal and NG were histologically and histochemically identical. Thesecretory endpieces consisted of three cell types: (1) Mucous cells (MC) with different types of mucous secretory granules with neutral and sialic acid-containing glycoconjugates (GCs). (2)Seromucous cells (SMC) showing a variety of moderately electron dense secretory granules with flocculent material with carboxylated acidic, neutral, and sialic acid-containing GCs. Intercellular canaliculi with junctional complexes and basolateral intercellular spaces were frequent. (3) Serous cells (SC) with electron dense secretory granules. Histochemically, they showed the strongest reaction for proteins and neutral, weakly acid and carboxylated acidic GCs.The epithelium of the intra- and inter-lobular excretory ducts showed secretory activity, junctional complexes, and wide basolateral intercellular spaces with lateral folds. The endpieces and ducts were surrounded by myoepithelial cells. The stroma was characterized by fenestrated endothelium, unmyelinated axons, and abundant plasma cells. MC, SMC, and the duct system were richly innervated by hypolemmal nerve terminals.

Major plasma lipids and fatty acids in four HDL mammals

Lipid classes and their fatty acids were compared in plasma from four mammals: a laboratory rodent, the mouse; two domestic animals, the cat and dog; and a wild animal, the South American armadillo, Chaetophractus villosus. In all, the most abundant lipoprotein was high-density lipoprotein (HDL). In the total lipid of plasma, phospholipids (PL) predominated in all four species, in correlation with the proportion of HDL, both being largest in dogs. The major PL was phosphatidylcholine (PC), followed by sphingomyelin (SM) and lysophosphatidylcholine. The total plasma lipid from the four species contained long-chain n-6 polyunsaturated fatty acids as the predominant acyl groups, followed by comparable proportions of total saturated and monoenoic fatty acids and small percentages of n-3 PUFA. The percentages of these four major groups of fatty acids in PC, SM, triacylglycerols and cholesterol esters were similar among species, but showed significant differences in the ratios between major individual fatty acids composing these groups.

Molecular Evolution of Leptin

Leptin, a hormone produced mainly by adipocytes, is involved in the regulation of food intake, metabolism, and reproduction. The objective of this study was to determine the evolutionary relationships of leptin genes. Partial nucleotide sequences of leptin were cloned and sequenced from six mammalian species: large hairy armadillo (Chaetophractus villosus), rabbit (Oryctolagus cuniculus), little brown bat (Myotis lucifugus), striped skunk (Mephitis mephitis), raccoon (Procyon lotor), and beluga whale (Delphinapterus leucas). The PUZZLE program was used to construct maximum-likelihood trees. Our phylogenetic analysis shows that the grouping of these new mammalian sequences with those currently available in GenBank respect the evolutionary relationships generally accepted for mammals. However, when leptin sequences for chicken and turkey are included in the analysis, these are found to group with mouse and rat leptins. Chicken and mouse leptins are 95% identical. However, when mouse is compared with closer relatives, such as rabbit or bat, identities are approximately 80%. A comparison of extant and ancestral leptin sequences suggests that convergent or parallel evolution is the most plausible hypothesis to explain the similarity between bird and rodent leptins.

Absence of penile erections during paradoxical sleep. Peculiar penile events during wakefulness and slow wave sleep in the armadillo.

The electroencephalogram (EEG) together with electromyogram (EMG) of the ischiocavernosus, bulbocavernosus and levator penis muscles were chronically monitored across behavioral states of the armadillo Chaetophractus villosus. This animal has a very long penis, which exhibits remarkable phenomena during wakefulness (W), slow wave sleep (SWS) and paradoxical sleep (PS). During W it remains retracted within a skin receptacle. During SWS penile protrusion can be observed together with very complex movements. Protrusion is a non erectile event during which the penis remains out of its receptacle but without rigidity. Penile erections are observed only during SWS. Contrasting with other mammals, no erections occur during PS. During this phase the penile muscles share the atonia of the body musculature characteristic of that phase. Some reflections on mechanisms of those penile events are presented.

Ultraestructura de los acinos sudoríparos de las glándulas pelvianas de Chaetophractus villosus (Mammalia, Dasypodidae)

The acini of pelvian glands of Chaetophractus villosus (Desmarest, 1804) consisted of an inner layer of secretory cells and an outer layer of myoepithelial cells. Secretory cells have numerous secretory vacuoles. The secretion is released by exocytosis. Myoepithelial cells have numerous myofilaments that occupy much of the cytoplasm. There is a third cell type with an extremely electron-lucent cytoplasm.

Micromamíferos del sitio Arroyo Seco 2 (provincia de Buenos Aires, Argentina). Sus implicaciones tafonómicas y paleoambientales

The late Pleistocene-early Holocene sequence at the Arroyo Seco 2 is one of the most complete record in Pampean Region. Four stratigraphic units are distinguished, three of which contain abundant small mammals fossil. Fossil bones from these units are analysed in order to determine the taphonomic processes and habitat present during the accumulation of their fauna remains. Most of the fossil bones are broken after burial. Bones from the deeper units are recovered of manganese (Mn) produced by the water level oscillations consequence of the successive swamping. Three species of armadillo ( Chaetophractus villosus, Dasypus hybridus and Zaedyus pichiy ) and four rodents ( Akodon azarae, Rheitrodon auritus, Ctenomys talarum and Lagostomus maximus ) are present. Record of micro-mammal plus megafauna evidence show a transition from temperate and semiarid to more humid conditions between 12,000 and 8,500 yrs BP.