Chaetophractus Villosus Research Articles

The vomeronasal organ of the South American armadillo Chaetophractus villosus (Xenarthra, Mammalia): anatomy, histology and ultrastructure.

The vomeronasal organ (VNO) is a chemoreceptive structure that has not been extensively studied in the Xenarthran order. Tissue samples from the VNO of the armadillo Chaetophractus villosus were prepared for light and electron microscopy. The VNO is located in the anterior part of the base of the nasal septum. It is tubular in shape, approximately 18 mm in length and opens in the rostral region of the nasal cavity and with a blind caudal end. Its lumen is lined by sensory (SE) and nonsensory (NSE) epithelium. The SE shows sensory, supporting and basal cells whereas the NSE contains ciliated and nonciliated secretory cells and basal cells. At the ultrastructural level, the sensory cells appear as bipolar neurons with conspicuous microvilli on their free surface. The supporting cells of the SE contain numerous membrane-bound vesicles in their apical regions. A peculiar feature not found in other mammals, is the presence of concentric whorls of RER cisterns frequently observed in their basal expansions. Infiltrating plasma cells can be detected in the SE basal region close to the dorsal junctional area. This region also exhibits an unusual type of basal cell, probably responsible for the generation of new vomeronasal receptor neurons. The ciliated NSE cells exhibit numerous ovoids or irregularly shaped membranous protrusions projecting from the plasma membrane of the cilia. As far as we know, this is the first study reporting the presence of this feature in ciliated NSE cells. The nonciliated cells are characterised by scarce large secretory granules and apical microvilli. The vomeronasal glands are compound-branched tubuloacinar glands with serous acinar cells. Four types of secretory granules are present. The ducts of these glands reach the lumen in the dorsolateral region between the NSE and SE. Hypolemmal nerve terminals were observed contacting secretory cells. Fenestrated and nonfenestrated capillaries constitute the vascular supply to these glands. Plasma cells, intimately associated with acinar cells, were frequently observed.

Identification and localisation of glycoconjugates in the olfactory mucosa of the armadillo Chaetophractus villosus.

Conventional histochemistry and the binding patterns of 22 biotinylated lectins were examined for characterisation of glycoconjugates in the components of the olfactory mucosa of the armadillo Chaetophractus villosus. The mucous lining the olfactory epithelium showed binding sites for DSL, WGA, STL, LEL, PHA-E and JAC. Only the basilar processes of the supporting cells stained for Con-A and S-Con A. The olfactory receptor neurons stained with LEL, LCA, Con A, S-Con A, JAC and PNA. The layer of basal cells did not react with any of the lectins studied. Bowman's glands in the lamina propria showed subpopulations of acinar cells reacting with SBA, S-WGA, WGA, STL, Con A, PSA, PNA, SJA, VVA, JAC and S-Con A, but in our optical studies with lectins we were unable to differentiate between mucous and serous cells in the way that is possible on electron microscopy. The ducts of Bowman's glands were labelled with S-WGA, STL, LEL, PHA-E, BSL-I and JAC. This histochemical study on the glycoconjugates of the olfactory mucosa in the order Xenarthra provides a basis for further experimental investigations.

Olfactory mucosa of the South American armadillo Chaetophractus villosus: an ultrastructural study.

The sense of olfaction in armadillos plays an important role, suggested by the great development of the nasal structures, olfactory bulbs, and related brain regions. The mammalian olfactory mucosa is a privileged site of neuronal death and regeneration during the whole life span. A detailed knowledge of its ultrastructure is convenient for gaining insight into the factors controlling those phenomena. We performed this work in species not previously studied in order to provide a firm basis for further research on those factors. No information is available on the histology and ultrastructure of the olfactory mucosa in the order Xenarthra to which armadillos belong. Samples from the endoturbinals of the armadillo Chaetophractus villosus were prepared for light and electron microscopic examination by the usual conventional means. The olfactory epithelium of Chaetophractus villosus shows the classical three types of cells: supporting cells, olfactory receptor neurons, and basal cells. The olfactory neurons and the basal cells were similar to that described in other species. Two different types of supporting cells are described. An outstanding characteristic of the supporting cells is the normal presence of abundant phagosomes, apical secretory granules, apocrine-like protrusions, and highly developed smooth endoplasmic reticulum. Apoptotic bodies are frequently found in the infranuclear cytoplasm of supporting cells. The ductular epithelium of Bowman's glands reveals secretory activity. The lamina propria shows mixed Bowman's glands. Great development of smooth endoplasmic reticulum is observed in the mucous acinar cells. Evidence for merocrine and apocrine mechanisms in the Bowman's glands is presented. The presence of apoptotic bodies and phagosomes in supporting cells suggests a participation in the cellular events induced by cell death and proliferation of the olfactory epithelium. The variety of characteristics exhibited by the supporting cells of the olfactory mucosa may contribute to a deeper understanding of their scarcely known functions.

Presence of a fatty acid-binding protein in the armadillo Harderian gland

A fatty acid-binding protein from the cytosolic fraction of the armadillo Chaetophractus villosus Harderian gland was purified to homogeneity by a procedure based on gel filtration and sodium dodecyl sulfate-polyacrylamide gel electrophoresis. The protein has an apparent molecular mass of 14 kDa. N-terminal sequence analysis showed that the protein has a blocked N-terminus. For internal amino acid sequencing, the protein was digested in-gel and the resulting peptides were fractionated by reverse-phase high performance liquid chromatography and subjected to automated Edman degradation. Partial amino acid sequencing suggests that it belongs to the heart type. Moreover, it cross-reacted with anti-serum to rat heart fatty acid-binding protein but not with rat intestinal and liver anti-sera. A very slow cross-reaction was also found with anti-serum to rat ALBP. This is the first time that a fatty acid-binding protein has been reported in a Harderian gland.

Purification and Partial Structural Characterization of a Fatty Acid-Binding Protein from the Liver of the South American Armadillo Chaetophractus villosus

The fatty acid-binding protein (FABP) from armadillo liver was purified to homogeneity by a procedure involving gel filtration and two anion exchange chromatography steps. The purified protein proved to have a pI between 5.0 and 5.2 and migrated by sodium dodecyl sulfate-polyacrilamyde gel electrophoresis as a single entity of approximately 14 kDa. The armadillo FABP cross-reacted with antiserum against rat liver FABP but not against rat intestinal FABP. The same as other members of the family, it has a blocked N-terminus. Amino acid sequencing of peptides obtained by cyanogen bromide cleavage and in-gel tryptic digestion shows that the armadillo, despite being one of the less evolved mammals, has a liver FABP of the same type as that of highly evolved mammals.

Bradycardia in armadillos experimentally covered with soil.

Chaetophractus villosus is able to maintain efficient respiratory movements when its nostrils are experimentally covered with soil. Under these conditions, a progressive bradycardia develops. It would depend on hypothermia and asphyxia.

Decrease of body temperature in armadillos experimentally covered by soil.

The armadillo Chaetophractus villosus does not stop breathing when experimentally covered with soil. Under that condition, there is a gradual but considerable drop in deep rectal temperature (TB): after 90 minutes, mean +/- SD = 1.7 +/- 0.4 degrees C (n = 8). As soon as the soil is removed and the animal breathes open air, TB gradually increases.

Consequences of Nest Desertion and Inattendance for Magellanic Penguin Hatching Success

Consequences of Nest Desertion and Inattendance for Magellanic Penguin Hatching Success

Body temperature of the armadillo Chaetophractus villosus (mammalia, dasypodidae).

Body temperature of the armadillo Chaetophractus villosus (n = 17) was studied during a period of 15 days. Deep rectal temperature (TB) was recorded at 9 am, 1 pm and 5 pm. Temperature in the laboratory was kept between 24.6 degrees C and 26.0 degrees C. We found two main different profiles of thermal behaviour in our animals, namely: a) one with high variation, mainly due to the daily cycle. b) the other with middle or low variation, with no predominance of the daily cycle. There were great TB differences between hours (P < 0.01). Morning temperatures were lower than the other ones. This is what could be expected in a non diurnal animal like C. villosus.

Host-Parasite Relationship Between Amazonian Anurans and Atypical Mycobacteria (Mycobacterium chelonei and M. fortuitum)

In a study of 450 Amazonian anurans, we isolated Mycobacterium chelonei abscessus, Mycobacterium fortuitum fortuitum, and Mycobacteriumfortuitum peregrinum from the viscera of 21 animals (Bufo marinus, Bufo granulosus, Hyla geographica, Hyla lanciformes, Hyla sp., Leptodactylus pentadactylus, and Leptodactylus sp.). We also detected M. chelonei abscessus, Mycobacterium chelonei chelonei, and M. fortuitum peregrinum in the soil and water samples of the anuran breeding ground. Adult toads (B. marinus) that had been force-fed a mycobacterial suspension retained and later excreted the microorganisms into their environment. Tadpoles of tree frogs (H. geographica) also ingested and retained mycobacteria that had been experimentally introduced into their milieu. Our findings indicated that the Amazonian anurans could play the role of a facultative intermediate host and dispersal agent for M. chelonei and M. fortuitum in nature. ATYPICAL MYCOBACTERIA ARE ACID-FAST BACILLI exclusive of the virulent mammalian tubercle bacilli Mycobacterium tuberculosis and Mycobacterium bovis. They are widespread in nature as saprophytes and parasites throughout the animal kingdom. According to the Runyon classification based on growth rate and pigment production, the group IV atypical mycobacteria are a rapid-growing species. Among the rapid growers, M. chelonei abscessus, M. chelonei chelonei, M. fortuitum fortuitum, and M. fortuitum peregrinum are known opportunistic pathogens for man and animals. They occur naturally as saprophytes in water, soil, and dust (Chapman 1971, Paull 1973, Romanelli et al. 1980). Although M. chelonei was originally isolated from diseased turtles (Friedmann 1903), the known animal hosts for M. chelonei and M. fortuitum are only the domestic hog and the armadillo, Chaetophractus villosus (Garcia-Rodriguez et al. 1975, Kantor 1978, S'aenz and

On the presence of a peculiar alpha rhythm in the olfactory tubercle of waking armadillos

A very regular 8–12 rhythm was found in the olfactory tubercle of the armadillo Chaetophractus villosus. The rhythm was observed during wakefulness. Considerable sinusoidal activity was also observed not only during wakefulness, but during synchronized (slow) and desynchronized (paradoxical) sleep. The significance of this novel rhythm is discussed together with considerations at establish an important difference between it and the other ‘alpha rhythms’ known.

Absence of apnea in armadillos covered by soil

The armadillo Chaetophractus villosus shows a remarkable respiratory adaptation when the nostrils are completely covered by soil: it is able to maintain efficient respiratory movements with the corresponding filling of the lungs, thanks to a mechanism that allows it to use the air filling the space between the soil particles, without invasion of the nasal cavities by those particles.

Discrimination Learning in the Armadillo (Chaetophractus villosus): A Study of Positional Strategies

Abstract Choice behavior of the armadillo Chaetophractus villosus (Edentata, Dasypodidae) was studied under laboratory conditions. Two groups were trained in a simultaneous visual discrimination task with food-reward. One group was trained with a contiguous spatial-temporal relationship between the discriminative stimulus and the reinforcement. For the second group, a spatial-temporal separation of these relevant stimuli was imposed in order to lengthen the presolution period. Attention was directed at determining which one of four positional strategies (alternation, position habit, win-shift/lose-stay, and win-stay/lose-shift) prevailed during the acquisition of the discrimination. There were no obvious differences in choice strategies between the groups, although the immediate spatial-temporal contiguity between the discriminative and reinforcing stimuli produced a significantly faster acquisition. Position habit was the only spatial strategy consistently observed between animals and maintained for a va...

The management and reproduction of the Large hairy armadillo at the National Zoological Park

The management and reproduction of the Large hairy armadillo at the National Zoological Park