Isotope data from amino acids indicate Darwin's ground sloth was not an herbivore

Fossil sloths are regarded as obligate herbivores for reasons including peculiarities of their craniodental morphology and that all living sloths feed exclusively on plants. We challenge this view based on isotopic analyses of nitrogen of specific amino acids, which show that Darwin's ground sloth Mylodon darwinii was an opportunistic omnivore. This direct evidence of omnivory in an ancient sloth requires reevaluation of the ecological structure of South American Cenozoic mammalian communities, as sloths represented a major component of these ecosystems across the past 34 Myr. Furthermore, by analyzing modern mammals with known diets, we provide a basis for reliable interpretation of nitrogen isotopes of amino acids of fossils. We argue that a widely used equation to determine trophic position is unnecessary, and that the relative isotopic values of the amino acids glutamate and phenylalanine alone permit reliable reconstructions of trophic positions of extant and extinct mammals.

Inhibitory action of thymol on fecal microbial activity in Tamandua tetradactyla and its effect on glucocorticoid metabolite measurement

Faecal glucocorticoid measurement is a potentially important tool for improving wildlife conservation, but its use is still limited by methodological issues including the need to avoid modifications of steroids by faecal microorganisms during storage. The freezing of faeces is recommended as a means of avoiding such alterations, but this is costly under non-controlled environmental conditions. The present study was designed to determine whether the application of thymol reduced the proliferation of microorganisms in the faeces of Tamandua tetradactyla and whether it influenced faecal glucocorticoid metabolite (FGM) measurements. Tamandua tetradactyla faeces were individually collected after defaecation, divided into fractions (5.5 g each) and kept in sealed glass Petri dishes at 22 ± 2 °C. A thymol solution (550 µL; 5 mg g^-1 feces; 80% ethanol) or an 80% ethanol solution (550 µL, control) was added before storage of faeces. Negative controls for FGM consisted of samples without thymol or ethanol solutions. All samples were evaluated at 0, 24, 48 and 72 h post-defaecation. Thymol was first incubated with a glucocorticoid standard in a faeces-free tube or in a faecal sample in order to determine whether it interfered with FGM measurements. Data showed that thymol did not affect FGM measurements. Post-defaecation time caused a significant reduction in FGM measurements in the negative control, an increment at 48 h in the control, and no change in FGM measurements in thymol treatment. FGM measurements were significantly different between groups (negative control > control - treatment). Thymol caused a significant reduction of up to three orders of magnitude in total coliforms, total aerobic and anaerobic heterotrophic mesophilic bacteria, mold and yeast per gram of faeces at 24, 48 and 72 h. The reduction in microbial activity presumably contributed to the stability of FGM over time. Spore-forming bacteria (SFB) in faeces were not reduced by thymol. We propose thymol as an alternative to freezing since it stabilizes FGMs for at least 3 days after collection in the faeces of Tamandua tetradactyla.

Mortality and morbidity in wild Taiwanese pangolin (Manis pentadactyla pentadactyla)

Globally, pangolins are threatened by poaching and illegal trade. Taiwan presents a contrary situation, where the wild pangolin population has stabilized and even begun to increase in the last two decades. This paper illustrates the factors responsible for causing mortality and morbidity in the wild Taiwanese pangolin (Manis pentadactyla pentadactyla) based on radio-tracking data of wild pangolins and records of sick or injured pangolins admitted to a Taiwanese wildlife rehabilitation center. Despite being proficient burrowers, results from radio-tracking show that Taiwanese pangolins are highly susceptible to getting trapped in tree hollows or ground burrows. Data from Pingtung Rescue Center for Endangered Wild Animals showed that trauma (73.0%) was the major reason for morbidity in the Taiwanese pangolin with trauma from gin traps being the leading cause (77.8%), especially during the dry season, followed by tail injuries caused by dog attacks (20.4%). Despite these threats, Taiwan has had substantial success in rehabilitating and releasing injured pangolins, primarily due to the close collaboration of Taiwanese wildlife rehabilitation centers over the last twenty years.

Fecal estrogen, progestagen and glucocorticoid metabolites during the estrous cycle and pregnancy in the giant anteater (Myrmecophaga tridactyla): evidence for delayed implantation

BACKGROUND

Declining numbers of wild giant anteaters highlight the importance of sustainable captive populations. Unfortunately, captive reproductive management is limited by the lack of external physical indicators of female reproductive status and the aggressive behavior of males. We examined the endocrinology of the estrous cycle and pregnancy, and whether delayed implantation is a gestational strategy for giant anteaters as described for other xenarthrans.

METHODS

Feces were collected from seven captive females 3-5 times weekly and mating was recorded. Concentrations of estrogen (estrone-glucuronide, E1, and estradiol-17β, E2), progestagen (20-oxo-progestagens, P4), and glucocorticoid (GC) metabolites were examined in fecal extracts by enzyme immunoassay.

RESULTS

Estrous cycles for nulliparous females (6 cycles, n = 2) compared to the multiparous female (6 cycles, n = 1) were shorter (47.3 +/- 4.3 days versus 62.5 +/- 2.6 days) with relatively lower luteal phase concentrations of P4 (49.4 +/- 2.9 ng/g versus 136.8 +/- 1.8 ng/g). The four remaining females had unclear ovarian activity: two females exhibited apparent luteal activity but unclear fluctuations in estrogens, while the other two females had parallel fecal P4 and estrogens concentrations. Pregnancy ranged 171-183 days with females returning to estrus post-partum as early as 60 days (n = 3, 1.8-4 years of age at mating). Delayed implantation was indicated by a biphasic elevation in fecal P4 metabolites: the initial 4-fold increase occurred for 81-105 days and was followed by a 26-fold secondary rise in P4 metabolites lasting 66-94 days prior to parturition. Fecal GC was correlated with fecal estrogens and greatest during estrus, late pregnancy, and six days prior to parturition (estrous cycle GC, 14.4-62.8 ng/g; pregnancy GC, 13.6-232.7 ng/g).

CONCLUSIONS

Estrous cycles of giant anteaters occurred year-round, but were shorter and more intermittent in younger nulliparous animals compared to a multiparous female. A pronounced elevation in fecal P4, estrogen, and GC occurred during late gestation after an initial post-mating delay providing evidence for delayed implantation. Adrenocorticoid activity indicated impending parturition. Differences in estrous cycle characteristics with age and the protracted but variable gestation length must be considered to improve reproductive success and neonatal survival in giant anteaters.

The fetomaternal interface in the placenta of three species of armadillos (Eutheria, Xenarthra, Dasypodidae)

BACKGROUND

Placental characters vary among Xenarthra, one of four supraordinal clades of Eutheria. Armadillos are known for villous, haemochorial placentas similar to humans. Only the nine-banded armadillo has been well studied so far.

METHODS

Placentas of three species of armadillos were investigated by means of histology, immunohistochemistry including proliferation marker, and transmission and scanning electron microscopy.

RESULTS

The gross anatomy differed: Euphractus sexcinctus and Chaetophractus villosus had extended, zonary placentas, whereas Chaetophractus vellerosus had a disk. All taxa had complex villous areas within the maternal blood sinuses of the endometrium. Immunohistochemistry indicated the validity of former interpretations that the endothelium of the sinuses was largely intact. Tips of the villi and the columns entering the maternal tissue possessed trophoblast cell clusters with proliferation activity. Elsewhere, the feto-maternal barrier was syncytial haemochorial with fetal vessels near the surface.

CONCLUSIONS

Differences among armadillos occurred in regard to the extension of the placenta, whereas the fine structure was similar. Parallels to the human suggest that armadillos are likely to be useful animal models for human placentation.

Conformational free energy of armadillo metmyoglobin

The conformational free energy of armadillo metmyoglobin was examined over a pH range of 4.4-8.0 and a guanidinium chloride concentration of 0-2.3 M. For isothermal unfolding at 25 degrees essentially the same value was obtained for the conformational free energy from all the data: 27 +/- 2 kJ/mol. These data suggest that the armadillo has the least stable metmyoglobin of any mammal thus far examined. The cooperativity of the unfolding with respect to denaturant is considerably less than for other mammalian myoglobins. On unfolding only three to four side chains with a pKA of 6 in the unfolded protein are protonated instead of the six found for horse and sperm whale myoglobins.

Classical bile acids in animals, beta-phocaecholic acid in ducks

1. Bile samples of different animals were analysed and the percentage content of classical bile acids was determined. 2. Herbivorous birds mostly excreted a large proportion of chenodeoxycholic acid. 3. The anteater (Myrmecophaga tridactyla) excreted deoxycholic acid most probably as a primary bile acid. 4. In the bile of ducks (Anas platyrhynchos) a large amount of (23R)3 alpha, 7 alpha, 23-trihydroxy-5 beta-cholan-24-oic acid (beta-phocaecholic acid) was found.

Lactate dehydrogenase in Mycobacterium leprae grown in armadillo liver

Lactate dehydrogenase (LDH) was detected in extracts of untreated and NaOH-treated Mycobacterium leprae. Since armadillo liver LDH isoenzymes with a similar electrophoretic mobility were shown to be considerably more sensitive to inhibition by oxamate than LDH in M. leprae extracts, it was confirmed that M. leprae grown in armadillo liver has its own LDH. Neither the activity of LDH in M. leprae nor its electrophoretic mobility supported the tentative suggestion that an "anomolous" LDH isoenzyme in infected skin biopsies was in fact an M. leprae-derived enzyme.

Variation of superoxide dismutase levels in extracts of Mycobacterium leprae from armadillo liver

Recent improvements in the sensitivity of assay methods for superoxide dismutase (SOD) have enabled the detection of this enzyme in 18 cell-free extracts of purified Mycobacterium leprae. By converting back to units of SOD obtained in the cytochrome c-based method previously used in work on this enzyme in mycobacteria, it was shown that extracts of M. leprae had 0.15-3.84 U SOD/mg protein (this study). A mean value of 1.31 U/mg protein was calculated. It was not possible to find any factors which could explain the very high levels in some extracts, although correlation with the period of tissue storage at -80 degrees C suggested that M. leprae in freshly killed tissue would have 1.77 U SOD/mg protein. The possibility of contamination by SODs from host and other organisms was unlikely since on gel electrophoresis extracts of M. leprae with high levels of SOD showed only a single band of activity characteristic of manganese-dependent SOD previously demonstrated.

Isolation and convulsivant effect of the "insulin-like" protein obtained from the exocrine pancreas of Bradypus tridactylus L

1. A pancreatic insulin-like protein fraction with low electrophoretic mobility showing high molecular weight is present. 2. Isoelectric focussing studies showed that the high molecular weight protein has a pI about 7.4 when used at a pH range between 3.5 and 8.0. 3. The partially purified aldehyde-fuchsin positive high molecular weight protein fraction gave a positive effect for the convulsivant test in mice. 4. A high molecular weight insulin-like protein in pancreatic juice was found. 5. Insulin was found by radioimmunoassay in the basal and post stimulation pancreatic juice.

Autoradiographic demonstration of estrogen uptake by the armadillo pituitary gland

Adult female armadillos were injected with tritiated estradiol. The pituitary gland was removed and processed for autoradiography. Nuclear uptake and retention of the steroid was found in 28.8% of the cells in the pars distalis and 3.7% of the pituicytes.

Pancreatic ribonucleases of mammals with ruminant-like digestion. Amino-acid sequences of hippopotamus and sloth ribonucleases

High levels of pancreatic ribonucleases are found in ruminants, species that have a ruminant-like digestion and several species with coecal digestion. Pancreatic ribonucleases from several independently evolved species with ruminant-like digestion were investigated to test a hypothesis that glycosylation of ribonucleases may have some function in species with coecal digestion and that glycosylation of the enzyme may not be advantageous for ruminants. Ribonucleases from the hippopotamus, two-toed sloth and three-toed sloth were isolated by extraction with sulfuric acid and affinity chromatography. Complete amino acid sequences were determined for the ribonucleases from the hippopotamus and two-toed sloth and a partial sequence for the enzyme from the three-toed sloth. The amino acids 75-78 of hippopotamus ribonuclease were positioned by homology with other artiodactyl ribonucleases. In hippopotamus ribonuclease a heterogeneity was found at position 37, half of the molecules containing glutamine acid the other half lysine. Hippopotamus ribonuclease differs less from pig and bovine ribonuclease than these differ from each other, because more ancestral characteristics have been retained. Although hippopotamus ribonuclease contains all four Asn-X-Ser/Thr sequences previously found to be glycosylation sites in one or more pancreatic ribonucleases, only the sequence Ans-Met-Thr (34-36) is glycosylated in the variant with glutamine at position 37, while the variant with lysine at this position is carbohydrate-free. Both sloth ribonucleases are completely glycosylated at the sequence Ans-Met-Thr (34-36) with a simple type of carbohydrate chain. The amino acid sequence of two-toed sloth ribonuclease shows some interesting coupled replacements.

Isolation of an acidic protein from the armadillo submandibular gland

An acidic protein fraction with an apparent molecular weight of 34 000 has been isolated from the Cetavlon-treated, mucin-free supernatant of the armadillo submandibular gland 0.01 M NaCl extract. This purified material, which was obtained in a yield of 0.45%/g wet gland, contains 24 mol % acidic amino acids and 4 mol % basic amino acids. Hexosamines, sialic acid, and neutral sugars represent 7% of the dry sample weight. In polyacrylamide gel and cellulose acetate electrophoresis, a single protein band was observed. The acidic protein fraction is highly reactive with the Lowry phenol reagent, giving a protein value 83% higher than that obtained by summation of its anhydrous amino acids, and is explained by the occurrence of peptide linkages peculiar to this material. The presence of other basophilic components besides mucus glycoproteins within the salivary gland of the armadillo may have physiological significance.

Structural studies on the carbohydrate units of armadillo submandibular glycoprotein

The structure of carbohydrate units of the major glycoprotein fraction of armadillo submandibular gland was investigated. Alkaline borohydride reductive cleavage of the glycoprotein resulted in the release of O-glycosidically linked mono- and disaccharide units. The monosaccharide was identified as N-acetylgalactosaminitol, whereas disaccharide contained of N-acetylneuraminic acid and N-acetylgalactosaminitol. Treatment of the native and desialyzed glycoprotein with alpha-N-acetylgalactosaminidase resulted in the removal of 60% and 96% of N-acetylgalactosamine, respectively. No cleavage of this sugar was affected by the action of beta-N-acetylhexosaminidase. Both N-acetylgalactosamine and N-acetylneuraminic acid were susceptible to oxidation with periodate. Analyses of the partially methylated N-acetylgalactosamine derivatives, obtained from the permethylated native glycoprotein, showed the presence of 3,4,6-tri-O-methyl-N-methylacetamidogalactose and 3,4-di-O-methyl-N-methylacetamidogalactose in a ratio of 1 : 0.4. Only 3,4,6-tri-O-methyl-N-methylacetamidogalactose was found in the hydrolysates of permethylated desialyzed glycoprotein. These results together with our previous data on chemical composition of the glycoprotein suggest that about 30% of the oligosaccharide chains consist of NeuAc alpha 2 leads to 6GalNAc alpha 1 leads to O-Thr(Ser) and 70% of GalNAc alpha leads to O-Thr(Ser).

Glucose metabolism by isolated fat cells from sloth

Glucose metabolism by sloth fat cells with and without addition of insulin was investigated. The data were compared to the results obtained with rat fat cells incubated under the same experimental conditions. Sloth fat cells showed a very low glucose oxidation to 14CO2 and incorporation into total lipids. The glucose incorporated into lipids is mainly in the glyceride-glycerol moiety. Addition of insulin did not produce an increase on glucose oxidation and a slight increase in the incorporation into total lipids was observed. Since it has been reported that sloths have a very low rate on thyroxine secretion, the results are discussed in relation to data in the literature on carbohydrate and lipid metabolism in hypothyroid animals.

Preparation and characterization of armadillo submandibular glycoproteins

The nine-banded armadillo (Dasypus novemcinctus mexicanus Peters) was chosen for this study so that a comparison could be made of the salivary mucus glycoproteins of an ancient mammalian species with those derived from previously studied, more highly evolved species. Two mucus glycoproteins, armadillo submandibular glycoprotein A and armadillo submandibular glycoprotein B, were prepared from the armadillo submandibular gland by a modification of the method of Tettamanti & Pigman (1968) (Arch. Biochem. Biophys. 124, 41-50). The composition of glycoprotein A is the simplest one among the known mucus glycoproteins. Six amino acids constitute 98.5 mol/100mol of the protein of glycoprotein A and 82 mol/100 mol of that of glycoprotein B. These are serine and threonine (which make up 40-50% of the molar amino acid composition), glutamic acid, glycine alanine and valine. Proline is absent from glycoprotein A and comprises only 2.3% of glycoprotein B. For both glycoproteins, the protein content, as determined by the method of Lowry, Rosebrough, Farr & Randall (1951) (J. Biol. Chem 193, 265-275), with bovine serum albumin as standard, was nearly 60% higher than when determined by the sum of the amino acids. The ratios of total mol of amino acid/total mol of carbohydrate are 1:0.63 for glycoprotein A and 1:0.68 for glycoprotein B, N-Acetylneuraminic acid and N-acetylgalactosamine, in a molar ratio of about 0.35:1.00, are the principal carbohydrates present in both glycoproteins. Neutral sugars seem to be absent from glycoprotein A, but galactose and fucose are present in glycoprotein B. The carbohydrate side chains in glycoprotein A are composed of about two-thirds monosaccharide and one-third disaccharide residues, whereas those of glycoprotein B are more complex. For both glycoproteins, essentially all of the N-acetylgalactosamine was attached O-glycosidically to the hydroxyamino acid residues of the protein core. The linkage of N-acetylneuraminic acid glycoprotein A was extremely sensitive to dilute acid and neuraminidase. Glycoprotein B has chemical properties similar to those of glycoprotein A. However, whereas glycoprotein A was susceptible to both Clostridium perfringens and Vibrio cholerae neuraminidases, only the latter enzyme had an effect on glycoprotein B at pH 4.75. Both glycoproteins were homogeneous by cellulose acetate electrophoresis and ultracentrifugal analyses. The apparent mol.wts. of glycoprotein A and glycoprotein B were 7.8 X 10(4) and 3.1 X 10(4) respectively.

The histochemistry of armadillo skin

The histochemistry of armadillo skin has been studied. The dendritic cells are extremely large, very sharply outlined by methods for alkaline phosphatase and alpha-naphthyl-acetate esterase, and they are dopa-negative. The mastocytes, however, are dopa-oxidase-positive, probably due to peroxidase rather than tyrosinase activity. The giant cells of the granulomas normally seen in the dermis of the armadillo are strongly beta-glucuronidase-positive. These giant cells are evidently foreign body cells reacting to the crystals always present in the dermis of the armadillo. The centre of these crystals, which are cholesterol and fat-negative, is alkaline phosphatase-positive. Further study of the mastocytes and dendritic cells is necessary to elucidate their nature.

Heterogeneity of bilirubin conjugates in several animal species

Bile was collected from various domestic and wild species (alligators, armadilirubin diazotized and subjected to thin-layer chromatography fro the separation of conjugates (as azo-dipyrroles). Diazotized canine conjugated bilirubin had Rf values in agreement with those previously reported by other; bilirubin conjugates were related to their known glycosidic composition. Variations were observed in the relative amounts of the various mono- and diconjugates among animals within species. However, it was apparent that characteristic patterns of bilirubin conjugation occur in certain animal species. Intravenous infusion of between 0.03 and 0.61 mg of bilirubin/Kg into cats resulted in little or no change in the relative percentages of the various conjugates of bilirubin to glucuronic acid in the cat continues to be the major excretory pathway under conditions of bilirubin load.