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What is a Suiforme (Artiodactyla)? Contribution of cranioskeletal and mitochondrial DNA data.

Suiformes (Artiodactyla) traditionally includes three families: Suidae, Tayassuidae, and Hippopotamidae but the monophyly of this suborder has recently been questioned from molecular data. A maximum parsimony analysis of molecular, morphological, and combined data was performed on the same set of taxa including representatives of the three Artiodactyla suborders (Suiformes, Ruminantia, and Tylopoda) and Perissodactyla as outgroup. Mitochondrial (cytochrome b and 12S rRNA) sequence comparisons support the monophyly of Suina (Suidae and Tayassuidae) and Ancodonta (Hippopotamidae) but not the monophyly of Suiformes. Inversely, our preliminary morphological analysis supports the monophyly of Suiformes whereas relationships among the three families are not resolved. The combined data set does not resolve the relationships between Suina, Ancodonta, and Ruminantia. These results are discussed in relation to morphological characters and paleontological data. Some improvements are suggested to clarify the morphological definition of Suiformes and relationships among them.

Animals↗

Higher taxonomic relationships among extant mammals based on morphology, with selected comparisons of results from molecular data.

Until a few decades ago, phylogenetic relationships among placental orders were ambiguous and usually depicted to radiate as an unresolved "bush." Resolution of this bush by various workers has been progressing slowly, but with promising results corroborated by nondental, dental, and molecular characters. In this study we continue to seek resolution. A total of 258 nondental and 2 dental characters was analyzed by PAUP and MacClade on 39 vertebrate taxa (3 reptiles, 1 nonmammalian therapsid, and 35 mammals; 20 of the mammals are extant and 15 are extinct) to study higher taxonomic relationships with emphasis on Placentalia (Eutheria). About two-thirds of the characters are osteological, the rest concern soft tissues, including myological but excluding molecular characters (most are our data, the rest are from the literature). Cladistic analysis included all 39 taxa (fossil taxa help to evaluate polarities of characters) and all characters were given equal weight. Extant Mammalia are divided into Prototheria and Theria, the latter into Marsupialia and Placentalia. Placentalia comprises Xenarthra and Epitheria. Within Epitheria, Lipotyphla and Preptotheria (emended) are sister-taxa. Preptotherian taxa group into: ungulate-related taxa and various nonungulates. The former include Carnivora, Pholidota, Tubulidentata, Artiodactyla, Cetacea, Perissodactyla, Hyracoidea, Proboscidea, and Sirenia. A possible association to embrace Lagomorpha, Rodentia, Macroscelidea, Scandentia, Primates, Chiroptera, and Dermoptera is suggested. Significant differences between our findings and those of recent investigators include the dissociation of Pholidota from Xenarthra and the plesiomorphous position of Lipotyphla within Epitheria. Congruence between morphological and molecular results is closer than previously reported.

Animals↗

Evolution of protamine P1 genes in mammals.

Protamine P1 genes have been sequenced following PCR amplification from 11 mammals representing five major mammalian orders: Rodentia (rat and guinea pig), Carnivora (cat and bear), Proboscidea (elephant), Perissodactyla (horse), and Artiodactyla (camel, deer, elk, moose, and gazelle). The predicted amino acid sequence for these genes together with previously reported sequences results in a data set of 25 different P1 genes and 30 different P1 amino acid sequences. The alignment of all these sequences reveals that protamines are amongst the most rapidly diverging proteins studied. In spite of the large number of differences there are conserved motifs that are also common to birds such as the N-terminal ARYR followed by the triple alternating SRSRSR phosphorylation site. The central region contains 3 arginine clusters consisting of 5-6 arginines each. The C-terminus appears to be the most variable region of the protamines. Overall the molecular evolution of P1 genes is in agreement with the expected species evolution supporting that these genes have evolved vertically.

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Morphological convergence in Hippidion and Equus (Amerhippus) South American equids elucidated by ancient DNA analysis.

Unusual equids named hippidions inhabited South America for more than 2 MY (million years). Like many other animals they succumbed to the worldwide climatic change that occurred 10 KY (thousand years) ago and completely disappeared during the great late Pleistocene megafaunal extinction. According to fossil records and numerous dental, cranial, and postcranial characters, Hippidion and Equus lineages are known to have diverged prior to 10 MY. Some equid bones from Rio Verde and Ultima Esperanza (Patagonia, Chile) dating back to the late Pleistocene period (8-13 KY) have been identified as Hippidion saldiasi, while a few teeth have been assigned to Equus. Six samples of those remains have been obtained from the Zoological Museum of Amsterdam for ancient DNA analysis to try to place Hippidion in the evolutive tree of Perissodactyla. Two samples of Hippidion and one sample of Equus yielded 241-394 bp of the mtDNA control region and 172-296 bp of the cytochrome b gene. Unexpectedly, all the sequences clustered deep inside the Equus genus, casting doubt on the initial identification of the bones. For paleontologists, one of the striking and classical diagnostic characters of Hippidion is their extremely short and massive metapodials, a probable locomotory adaptation to the Andine steep slopes. However, our DNA analysis reveals that a very Hippidion-like metapod might also have been possessed by another South American equid, i.e., Equus (Amerhippus), an interpretation supported by complementary anatomical observations. This adaptive convergence between members of the two South American equid genera may lead paleontologists to limb bone misidentification.

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Monophyletic origin of the order chiroptera and its phylogenetic position among mammalia, as inferred from the complete sequence of the mitochondrial DNA of a Japanese megabat, the Ryukyu flying fox (Pteropus dasymallus).

Complete sequences of mitochondrial DNA (mtDNA) are useful for the reconstruction of phylogenetic trees of mammals and, in particular, for inferring higher-order relationships in mammals. In this study, we determined the complete sequence (16,705 bp) of the mtDNA of a Japanese megabat, the Ryukyu flying fox (Pteropus dasymallus). We analyzed this sequence phylogenetically by comparing it with the complete sequence of mtDNAs of 35 mammals in an effort to reevaluate the enigmatic relationship between Megachiroptera and Microchiroptera and the relationships between them and other mammals. Maximum-likelihood analysis of 12 concatenated mitochondrial proteins from 36 mammals strongly suggested the monophyly of the order Chiroptera and its close relationship to Fereuungulata (Carnivora + Perissodactyla + Cetartiodactyla). We estimated that megabats and microbats diverged approximately 58 MyrBP and discussed the origin and early evolution of Chiroptera based on our findings.

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Maximum likelihood analysis of the complete mitochondrial genomes of eutherians and a reevaluation of the phylogeny of bats and insectivores.

The complete mitochondrial genomes of two microbats, the horseshoe bat Rhinolophus pumilus, and the Japanese pipistrelle Pipistrellus abramus, and that of an insectivore, the long-clawed shrew Sorex unguiculatus, were sequenced and analyzed phylogenetically by a maximum likelihood method in an effort to enhance our understanding of mammalian evolution. Our analysis suggested that (1) a sister relationship exists between moles and shrews, which form an eulipotyphlan clade; (2) chiropterans have a sister-relationship with eulipotyphlans; and (3) the Eulipotyphla/Chiroptera clade is closely related to fereuungulates (Cetartiodactyla, Perissodactyla and Carnivora). Divergence times on the mammalian tree were estimated from consideration of a relaxed molecular clock, the amino acid sequences of 12 concatenated mitochondrial proteins and multiple reference criteria. Moles and shrews were estimated to have diverged approximately 48 MyrBP, and bats and eulipotyphlans to have diverged 68 MyrBP. Recent phylogenetic controversy over the polyphyly of microbats, the monophyly of rodents, and the position of hedgehogs is also examined.

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MHC class I genes of the tree shrew Tupaia belangeri.

Two MHC class I cDNA sequences from the tree shrew (Tupaia belangeri), Tube-W01 and Tube-W02, have been isolated which are probably derived from classical class I genes. Expression of the tupaia class I genes was investigated in several organs, in particular the brain, in which slightly different amounts of class I transcripts are detectable in different areas. Gene tree analysis performed with Tube-W01 and Tube-W02, and including class I sequences derived from other orders, indicated that the tupaia sequences cluster differently from Primates, Carnivora, Artiodactyla, Perissodactyla, and Rodentia, but might be related to Lagomorpha class I genes.

Amino Acid Sequence↗

Isolation from the horse genome of a new DNA transposon belonging to the Tigger family.

Tigger elements are human DNA transposons homologous to the pogo element of Drosophila melanogaster. They contain an open reading frame for a transposase very similar to the major mammalian centromere protein CENP-B. We found in the horse genome a DNA element ( Ecatig3) sharing 88% homology with human Tigger3. The presence of Tigger elements in the horse genome confirms previous data that date these elements before the divergence between Perissodactyla and Primates (80-90 Myr ago). Copy number evaluation indicates that the horse element is much more abundant than its human counterpart. Southern blot analysis demonstrates that Ecatig3 elements are extremely homogeneous; this may indicate that the evolution of this DNA transposon has been driven by some kind of selection and has not been neutral.

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Identification of fetuin in human and rat fetuses and in other species.

The fetal protein, fetuin, has previously only been identified in species belonging to the order Artiodactyla. Samples of fetal, newborn and adult human (Homo sapiens) and rat (Rattus norvegicus) plasma and tissues have been studied using three techniques: (a) crossed immunoelectrophoresis of plasma against each of four different anti-fetuin antisera (two anti-cattle, one anti-pig and one anti-sheep); (b) the peroxidase-antiperoxidase technique applied to agarose gels containing plasma spots; (c) the indirect immunoperoxidase technique applied to human fetal tissue sections. In human fetal samples all three methods gave evidence for the presence of fetuin except late in gestation and in the newborn. Adult plasma was negative. In rat fetuses only plasma was tested, by methods (a) and (b). Positive reactions were obtained for both fetal and adult samples; the fetal samples cross-reacted with several of the anti-fetuins, adult samples reacted with only one. All the fetal and embryonal plasma samples tested with the peroxidase-antiperoxidase method were positive for fetuin except for the chicken. Thus fetuin appears to be distributed in at least five mammalian orders (Artiodactyla, Primates, Rodentia, Carnivora and Perissodactyla).

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Amino acid sequences of P1 protamines and the phylogeny of eutherian mammals: a cladistic study.

Amino acid and cDNA sequences of eutherian P1 protamines, known from publications of other authors, were compared by a cladistic method. Fish, toad and bird protamines were used for the pertinent "outgroup comparisons", i.e. they provided relevant data for the comparative alignment of the sequences and for the recognition of evolutionary trends. In the sequence positions compared, each amino acid was individually assigned as a plesiomorphic or apomorphic character state (qualitative treatment). The resulting phylogenetic tree (Fig. 2) is only partially in accordance with common ideas on eutherian phylogeny. Disagreements refer to the branching points of Perissodactyla, Lagomorpha and Rodentia.

Amino Acid Sequence↗

On the phylogenetic position of a rare Iberian endemic mammal, the Pyrenean desman (Galemys pyrenaicus).

The nucleotide sequences of the complete mitochondrial genome and nine partial nuclear genes of the Pyrenean desman (Galemys pyrenaicus) were determined in order to establish the relative phylogenetic position of this species at different taxonomic levels within the placental tree. Phylogenetic relationships of desman within the family Talpidae were inferred based on complete mitochondrial cytochrome b gene nucleotide sequence data. The Pyrenean desman was unambiguously recovered as sister group of the Russian desman (Desmana moschata) confirming the monophyly of the subfamily Desmaninae. However, phylogenetic relationships among major lineages within the Talpidae could not be confidently resolved. Phylogenetic analyses based on mitochondrial (at the amino acid level) and nuclear (at the nucleotide level) sequence data sets confidently placed desman within the Eulipotyphla (that also included moles, shrews, and hedgehogs), and partially recovered placental interordinal relationships. The monophyly of Laurasiatheria (including Eulipotyphla, Chiroptera, Carnivora, Pholidota, Perissodactyla, and Cetartiodactyla) was strongly supported. Mitochondrial amino acid sequences of Pholidota (pangolins) were found to bias phylogenetic inferences due to long-branch attraction effects. A Bayesian inference based on a combined mitochondrial and nuclear data set without Pholidota arrived at an almost fully resolved tree that supported the basal position of Eulipotyphla within Laurasiatheria.

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Environment and evolution through the Paleocene-Eocene thermal maximum.

The modern orders of mammals, Artiodactyla, Perissodactyla and Primates (APP taxa), first appear in the fossil record at the Paleocene-Eocene boundary, c. 55 million years ago. Their appearance on all three northern continents has been linked to diversification and dispersal in response to rapid environmental change at the beginning of a worldwide 100 000-200 000-year Paleocene-Eocene thermal maximum (PETM) and carbon isotope excursion. As I discuss here, global environmental events such as the PETM have had profound effects on evolution in the geological past and must be considered when modeling the history of life. The PETM is also relevant when considering the causes and consequences of global greenhouse warming.

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Cloning and sequence analysis of llama (lama glama) Th2 (IL-4, IL-10 and IL-13) cytokines.

This paper describes the cloning and sequence analysis of the cDNAs encoding the T helper (Th) 2 cytokines of llama including interleukin-4 (IL-4), IL-10 and IL-13. The cDNAs encoding for IL-4, IL-10 and IL-13 were amplified using specific primers designed from reported sequences of bovine cytokine genes. The cDNAs for llama IL-4, IL-10 and IL-13 were found to be 402, 537 and 411 bp in length, with open reading frames encoding 133, 178 or 136 amino acids, respectively. Homology analyses of nucleotide and deduced amino acid sequences of llama IL-4, IL-10 and IL-13 and phylogenetic analysis based on their nucleotide sequences indicated the close relationship in these cytokine genes between llama and eutherian mammalian order Artiodactyla (pig, cattle) and Perissodactyla (horse).

Amino Acid Sequence↗

The broad spectrum of Trichinella hosts: from cold- to warm-blooded animals.

In recent years, studies on Trichinella have shown that the host range is wider than previously believed and new Trichinella species and genotypes have been described. Three classes of vertebrates are known to act as hosts, mammals, birds and reptiles, and infected vertebrates have been detected on all continents but Antarctica. Mammals represent the most important hosts and all Trichinella species are able to develop in this vertebrate class. Natural infections with Trichinella have been described in more than 150 mammalian species belonging to 12 orders (i.e., Marsupialia, Insectivora, Edentata, Chiroptera, Lagomorpha, Rodentia, Cetacea, Carnivora, Perissodactyla, Artiodactyla, Tylopoda and Primates). The epidemiology of the infection greatly varies by species relative to characteristics, such as diet, life span, distribution, behaviour, and relationships with humans. The non-encapsulated species Trichinella pseudospiralis, detected in both mammals (14 species) and birds (13 species), shows a cosmopolitan distribution with three distinguishable populations in the Palearctic, Nearctic and Australian regions. Two additional non-encapsulated species, Trichinella papuae, detected in wild pigs and saltwater crocodiles of Papua New Guinea, and Trichinella zimbabwensis, detected in farmed Nile crocodiles of Zimbabwe, can complete their life cycle in both mammals and reptiles. To the best of our knowledge, T. papuae and T. zimbabwensis are the only two parasites known to complete their entire life cycle independently of whether the host is warm-blooded or cold-blooded. This suggests that these two Trichinella species are capable of activating different physiological mechanisms, according to the specific vertebrate class hosting them.

Animals↗

Amblyomma aureolatum (Pallas, 1772) and Amblyomma ovale Koch, 1844 (Acari: Ixodidae): hosts, distribution and 16S rDNA sequences.

DNA sequences of Amblyomma aureolatum (Pallas, 1772) and Amblyomma ovale Koch, 1844 were obtained to determine genetic differences between these tick species. Collections of these species are discussed in relation to distribution and hosts. Seven ticks collections (four from Brazil, one from Argentina, one from Uruguay and one from USA) house a total of 1272 A. aureolatum (224 males, 251 females, 223 nymphs and 574 larvae) and 1164 A. ovale (535 males, 556 females, 66 nymphs and 7 larvae). The length of the sequenced mitochondrial 16S rRNA gene fragment for A. aureolatum was 370bp and for A. ovale was 373bp. The DNA sequence analysis showed a 13.1% difference between the two species. Apart from one male A. ovale found on a toad, all adult ticks were found on mammals. The majority of adult specimens of both tick species were removed from Carnivora (96.1 and 84.3% of A. aureolatum and A. ovale, respectively), especially from dogs (53.1% of A. aureolatum, and 46.4% of A. ovale). Collections on wild Canidae were higher for A. aureolatum (23.3%) than for A. ovale (7.1%). On the other hand, collections of A. ovale adults on wild Felidae were higher (18.3%) than findings of A. aureolatum (9.2%). The contribution of other mammalian orders as hosts for adults of A. aureolatum and A. ovale was irrelevant, with the exception of Perissodactyla because Tapiridae contributed with 13.0% of the total number of A. ovale adults. Adults of both tick species have been found occasionally on domestic hosts (apart of the dog) and humans. Most immature stages of A. aureolatum were found on Passeriformes birds, while rodents and carnivores were the most common hosts for nymphs and larvae of A. ovale. A. aureolatum has been found restricted to the Neotropical region, covering the eastern area of South America from Uruguay to Surinam, including northeastern Argentina, eastern Paraguay, southeastern Brazil and French Guiana. A. ovale showed a distribution that covers the Neotropical region from central-northern Argentina throughout the Neotropics into the Nearctic region of Mexico with a few records from the USA, also with collection sites in Paraguay, Bolivia, most Brazilian states, Peru, Ecuador, French Guiana, Surinam, Guyana, Trinidad & Tobago, Venezuela, Colombia, Panama, Costa Rica, Nicaragua, Belize, Guatemala and several states of Mexico.

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Cross reactivities among some mammalian haptoglobins studied by a monoclonal antibody.

Mouse monoclonal antibody antihuman-Hp, product of clone 2.36.71.41 was found to recognize, however, with different affinities, the immunological determinant on haptoglobin of some mammals (goat, sheep, cow, horse, rabbit). The following differences in immunological cross reactivities were noticed: (i) haptoglobins present in sera of goat, sheep and cow (Artiodactyla, Bovidae) react in enzyme-linked immunosorbent assay (ELISA) and form precipitates in agarose gel; (ii) horse (Perissodactyla) and rabbit (Lagomorpha) haptoglobins react in ELISA, but they do not form precipitates; and (iii) haptoglobins of dog, fox, cat (Carnivora) and pig (Artiodactyla, Suidae) are not recognized by the tested monoclonal antibody either in ELISA or in agarose gel. This study suggests that monoclonal antibody, clone 2.36.71.41, recognizes the structure on haptoglobin around the disulphide bond linking two alpha chains. Antigenic structure of Bovidae haptoglobins is rather similar to human haptoglobin 2-2 (circular polymers) than to 2-1 type (linear polymers). Monoclonal antibody 2.36.71.41 could be used for classification of mammalian haptoglobins by epitope structure. It can distinguish polymeric haptoglobins similar to human type 2-2 from other mammalian haptoglobins.

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The "human"-like morphology of the swine papilla ilealis.

The morphology of the ileocecocolic transition, between the small and large intestine was studied in 33 male, adult pigs of unknown breed. The results were analyzed by the Wilcoxon Test (alpha < or = 0.05). The ileum opened into the large intestine, in all of the cases, at the level of the cecocolic junction in the form of a conical papilla (ileal papilla) turned towards the large intestine, with an oblique caudal and lateral direction, pointing to the cecal lumen. The cranial contour is higher than the caudal one, with average values of 3.0 cm, and 1.5 cm in the fresh specimens and 2.8 cm and 1.4 cm after fixation of the specimens. The average diameter of the papilla apex was 1.5 cm, both in the fresh specimens and in the fixed ones. In 100% of the cases the ileal papilla appeared with a star-shaped orifice in its apex in both the fresh and in the fixed specimens. Our studies showed that the transition between the small and large intestine of the swine is ileocecocolic, thus similar to humans and different from the ileocecal (Perissodactyla, Rodentia, Lagomorpha) and, according to most descriptions, ileocolic (dog) transitions found in other animals.

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Taxeopody in the carpus and tarsus of Oligocene Pliohyracidae (Mammalia: Hyracoidea) and the phyletic position of hyraxes.

Recent hyracoids and elephants share a taxeopode arrangement of tarsal and carpal bones, a condition in which bones are aligned with minimal interlocking between adjacent elements. Taxeopody has often been interpreted as a synapomorphy reflecting a close phyletic link between Hyracoidea and Proboscidea, but recently it has been suggested [Fischer, M. S. (1986) Cour. Forschungsinst. Senckenberg 84, 1-132] that hyracoid taxeopody is an independent acquisition resulting from selection favoring increased midcarpal and midtarsal rotation and that Hyracoidea is actually allied with Perissodactyla. As a test of this hypothesis, isolated carpal and tarsal bones of primitive Oligocene hyracoids from the Fayum, Egypt, have been examined to determine whether these indicate a taxeopode or diplarthral carpus and tarsus. Four complete astragali from the Fayum, representing at least three taxa, show a single, slightly convex articular surface on the head for articulation with the navicular and lack a facet for the cuboid. Two complete magna representing two species have a single proximal facet for articulation with the lunar, and they lack a facet for the scaphoid. Thus, both the carpus and tarsus of Fayum hyracoids are taxeopode. Taxeopody in hyracoids cannot be attributed to selection for carpal and tarsal rotation in climbers because the Oligocene, Miocene, and Recent species show great diversity in body size and probably locomotor specializations, despite relative uniformity of structure in the carpus and tarsus. The shared taxeopody of hyracoids and proboscideans, along with other osteological characters and similarities in hemoglobin, eye lens proteins, and other molecules, all suggest that Hyracoidea belongs within Paenungulata.

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