Jorge M. Affanni

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.

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, ∼ 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. Bowmans 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 Bowmans 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.

Characterisation of glycoconjugate sugar residues in the vomeronasal organ of the armadillo Chaetophractus villosus (Mammalia, Xenarthra).

Conventional carbohydrate histochemistry and the binding patterns of 21 lectins were analysed to characterise the glycoconjugate content in the components of the vomeronasal organ of the armadillo Chaetophractus villosus. The mucomicrovillous complex of the sensory epithelium bound most of the lectins studied. No reaction was observed with Con A, PSA, S‐Con A and SBA, and the sustentacular cells were stained with UEA‐I, DSL, LEL, STL and Con A. The vomeronasal receptor neurons were labelled with S‐WGA, WGA, PNA, UEA‐I, STL, Con A, S‐Con A, ECL and RCA120. The basal cell layer reacted with S‐WGA, WGA, LCA, UEA‐I, DSL, LEL, STL, Con A, JAC and VVA. The nonsensory epithelium exhibited a differential staining in relation to the different components. The mucociliary complex stained with ECL, DBA, JAC, RCA120, STL, LCA, PHA‐E, PHA‐L, LEL, BSL‐I and VVA. However, SJA and UEA‐I stained the mucus complex lining a subpopulation of columnar cells. The cytoplasm and cell membranes of columnar cells was labelled with DBA, DSL and LCA. The apical region of these cells exhibited moderate reactivity with LEL and SJA. None of the lectins bound specifically to secretory granules of the nonsecretory cells. Basal cells of the nonsensory epithelium were labelled with DSL, LEL, LCA, BSL‐I and STL. The vomeronasal glands showed a positive reaction with WGA, DSL, LEL, LCA, DBA, PNA, RCA120 and SBA. Subpopulations of acinar cells were observed with ECL, S‐WGA, Con A, S‐Con A and DBA. PNA and RCA120 stained the cells lining the glandular ducts. In comparison with previous results obtained in the olfactory mucosa of the same group of armadillos, the carbohydrate composition of the vomeronasal organ sensory epithelium differed from the olfactory sensory epithelium. This is probably related to the different nature of molecules involved in the perireceptor processes.

Spatial Learning in South American Opossums and Armadillos

This experiment compares spatial learning in the South American opossum (Didelphis albiventris) and armadillo (Chaetophractus villosus) in a Y-maze. Ss learned to turn to one arm of the maze for food reinforcement. To earn further reinforcements, they had to return to the start-box (after consuming the food) where they were restrained for a fixed intertrial interval. The number of entries to the unbaited arm en route to the goal-box (Ri errors), and in the way back to the start-box (Rf errors) were the dependent measures. Opossums and armadillos did not differ in Ri errors. However, only armadillos mastered the task of returning directly to the start-box after each reinforcement. Moreover, a significant within-session improvement in Rf errors was observed in armadillos, but failed to appear in opossums. Results are discussed in terms of species differences in sensitivity to temporal delays.

Acyl-CoA-binding protein in the armadillo Harderian gland: its primary structure and possible role in lipid secretion.

Similar to those of other species, the Harderian glands of armadillo produce an abundant lipid secretion, most of which is composed of 1-alkyl-2,3-diacylglycerol. Biosynthesis of this component is apparently performed with the participation of one cytosolic pool of acyl-CoA and another of free fatty acids. The acyl-CoA-binding protein (ACBP) is present at a concentration at least 7-fold that of the heart-type fatty acid-binding protein (H-FABP), though lower than that in other armadillo organs such as liver and brain. The ACBP complete amino acid sequence was determined by Edman degradation of peptides generated by cleavage of the protein with cyanogen bromide, endopeptidase Glu-C, and trypsin. ACBP consists of 86 residues and has a calculated molecular mass of 9783 Da, taking into account that an acetyl group is blocking the N-terminus. Identity percentages between armadillo Harderian gland ACBP and other known ACBPs show that the protein belongs to the liver-specific ACBP isoform (L-ACBP). The fact that the ACBP concentration is higher than that of FABP suggests that the Harderian gland is able to store acyl-CoA amounts in ACBP larger than those of fatty acids in H-FABP for 1-alkyl-2,3-diacylglycerol synthesis.

A novel receptive area of key importance for the onset of diving responses in the duck

We have found that the stimulation of the mucosa of the rhinopharynx elicits apnea and bradycardia in the duck. This appears to be the most important area involved in the production of diving responses. The laryngeal mucosa and other areas, as the external nares, were found to be of lesser relevance. We have also observed that visual and thermal stimuli may participate in the elicitation of the responses to submersion.

Ultrastructural characterisation of the olfactory mucosa of the armadillo Dasypus hybridus (Dasypodidae, Xenarthra)

The ultrastructure of the olfactory mucosa of the armadillo Dasypus hybridus was studied. A comparison with the olfactory mucosa of another armadillo (Chaetophractus villosus) was made. The olfactory mucosa of D. hybridus shows many features which are similar to those of other mammals. Interestingly, it differs from the olfactory mucosa of the armadillo C. villosus. A suggestion is made that these differences may be due to differences in the digging habits of these species. In Dasypus, the supporting cells (SCs) showed dense vacuoles, multivesicular bodies and lysosome‐like bodies probably related with the endocytotic system. The SCs show a dense network of SER presumably associated with xenobiotic mechanisms. The olfactory receptor neurons exhibit lysosome‐like bodies and multivesicular bodies in their perikarya. These organelles suggest the presence of an endocytotic system. Duct cells of Bowmans glands exhibit secretory activities. Bowmans glands are compound‐branched tubulo‐acinar mixed glands with merocrine secretory mechanisms.

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.

Neocortical and olfactory bulb activity, in armadillos submitted to covering with soil

Armadillos were submitted to an experimental condition in which their head and thorax were covered by a layer of soil 30 cm high. In this condition the electrical activity of the neocortex and of the olfactory bulbs was studied. Neocortical activity did not show signs of damage remaining without gross changes before, during and after the covering with soil. The olfactory bulbs showed a great decrease of bursting sinusoidal activity which almost instantaneously reversed when the soil was removed. The mechanisms of these changes are discussed.