Histology, extensibility and chemical composition of the pulmonary trunk of dogs, sheep, cattle and llamas living at high altitude.
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The density of mast cells in various anatomical locations within the lung were measured in a peruvian Andean llama, a Peruvian Andean cow and a sea-level-cow. These densities were determined separately around pulmonary arteries, pulmonary veins, pulmonary arterioles and venules, in the alveolar septa, and around bronchi. The total mast cell density did not differ significantly between the three animals and there were more periarteriolar and perivenular mast cells in the llama than in either of the two cows. These data do not support the hypothesis that the perivascular mast cell is responsible for initiating the vasopressor response to hypoxia. In fact it can be argued that they actually inhibit this response since a high mast cell density was found in the llama, and animal which does not develop pulmonary hypertension at high altitude.
Karyotype analysis of a premature human acardiac twin disclosed normal chromosomes. A review of previous cytogenetic, placental and animal studies suggests that chromosomal errors are not the cause of the acardiac anomaly. Rather, they point to the placental vascular anastomoses as the principal pathogenetic event.
The relative binding affinity of 5 alpha-reduced progestins and a newly synthesized antiprogestin J912 (progesterone 100%) was determined in a competitive receptor binding assay using [3H]ORG-2058 as radiolabeled ligand for the progestin receptor. Uteri obtained from 12 different species of four mammalian orders were examined. The relative binding affinity of 75-100% and a blood prevalence of 5 alpha-pregnane-3,20-dione in horses and African elephants suggest a biological role of this particular 5 alpha-reduced progesterone. For pigs the binding affinity of 5 alpha-pregnane-3,20-dione was about 50% of progesterone, but blood levels are unknown. In all other cases the low binding affinity of investigated progestins precludes possible biological role. For 5 alpha-pregnane-3 alpha-ol-20-one, 5 alpha-pregnane-20 alpha-ol-3-one, and 5 alpha-pregnane-3 beta,20 alpha-diol the relative binding affinity was less than 1%. A rather low binding (< 15%) was observed in 5 alpha-pregnane-3,20-dione in all ruminant species investigated. The antiprogestin J912 was found to be highly efficient in displacing progesterone from its endometrial binding sites in carnivores and might therefore be used for pregnancy interruption during diapause in certain species, e.g., in captive bears.
In 1978 three well-preserved pieces of a fossil human cranium (i.e., fused parietals, occipital and temporal) were found in a gravel pit near the southwest German town of Reilingen. It was recovered, with an accompanying mammalian fauna, as a side-product of commercial gravel mining. The sample was sorted from the dredgings of a boat-mounted crane reaching to a depth of 28 m below the surface. Here we present the mammalian fauna and discuss its biostratigraphical relevance. The fauna represents a mixture of Holstein interglacial to Würm glacial species. The occurrence of Holsteinian faunal components is indicated by presence of the extinct beaver, Trogontherium. Given the good preservation of specimens found at the lowest levels we can rule out reworking. The accompanying fauna indicates a Holstein to Würm time span bracketing the fossil hominid population.
The Muruyur Beds are a substantial sedimentary deposit within a middle Miocene sequence of mafic volcanic flows associated with early stages of rifting in the central Kenyan Rift Valley. They are best represented in the Muruyur region, near Bartabwa, north of Kipsaramon, where dates range from 16.0 to 13.4 Ma. At Kipsaramon, located about 10 km south of Muruyur along the crest of the Tugen Hills, the upper Muruyur Beds are absent and the lower part can be divided into three members. Important fossil sites within Member 1 are dated between 15.8 and 15.6 Ma, and within Member 3 between 15.6 and 15.4 Ma. BPRP#89, in Member 1, is a bonebed at least 2500 m(2)in areal extent and up to 30 cm thick, which constitutes one of the richest concentrations of in situ fossil vertebrate bones in eastern Africa. BPRP#91, at approximately the same level at BPRP#89, is the source of a hominoid talus and other mammal and bird fossils. In Member 3, BPRP#122 has produced specimens of at least five individuals of the hominoid Equatorius, including a partial skeleton. The Muyuyur Beds were deposited near the western margin of a lake that was formed during the early stages of faulting and volcanism in the African Rift system. The bonebed in Member 1 appears to represent the influx of fluvially transported vertebrate and plant remains into a shallow portion of the lake. Elements of the fauna as well as stable isotopes that indicate both forest and more open environments occurred in proximity to the lake during the time of deposition of Member 1.
Current knowledge about mammalian interordinal relationships is growing rapidly; thus this contribution is an attempt to summarize the past 5 years of this literature. We have focused on the recent controversies in mammalian phylogenetics including hypotheses concerning the monophyly of Archonta, the diphyly of Chiroptera, and the polyphyly of Rodentia. All of these issues have been proposed recently, challenging these phylogenetic hypotheses. We have attempted to include all of the comprehensive analyses of eutherian mammal systematics with an emphasis on morphological and molecular data sets where discrete characters are listed so they could be compiled and used in support of interordinal relationships. Particular attention is given to determining which of the living eutherian orders is the closest relative to primates. In reviewing relationships among the mammals, we have focused on collating all of the available evidence so that one could know where each of the specific data sets is in support of the various relationships.
By using the maximum likelihood method, we study the reliability of phylogeny based on only four taxa, which have been studied by Philippe and Douzery with the maximum parsimony and neighbor-joining methods. Amino acid sequences of cytochrome b were provided for the analysis to examine the relationships among Ruminantia, Suiformes, and Cetacea with out-group mammals by using one representative species from each group. In accord with Philippe and Douzery's analysis, it was shown that we can find a quartet of species which provides a high bootstrap proportion for each of the three possible trees and that the quartet analyses with only four species can be misleading even with the maximum likelihood. However, if the confidence level of the inferred tree is estimated adequately by the maximum likelihood method and we take a conservative attitude, we can avoid the danger of concluding an erroneous tree by using quartet analysis, although the problem may remain unresolved in many cases. In order to obtain a reliable tree, it is important to carry out analyses based on as many different genes and as many relevant species as possible and to synthesize the results.
The family Bovidae is characterized by an incomplete fossil record for the period during which most bovid subfamilies emerged. This, coupled to extensive morphological convergence among species, has given rise to inconsistencies in taxonomic treatments, especially at the tribal and subfamilial levels. In an attempt to clarify some of these issues we analyzed the complete mtDNA cytochrome b gene (1140 bp) from 38 species/subspecies representing at least nine tribes and six subfamilies. Specific emphasis was placed on the evolution of the Alcelaphini (hartebeest and wildebeest), the Tragelaphini (kudu, eland, and close allies), the Antilopini (gazelles), and the Neotragini (dwarf antelope). Saturation plots for the codon positions revealed differences between bovid tribes and this allowed for the exclusion of transitional substitutions that were characterized by multiple hits. There was no significant rate heterogeneity between taxa. By calibrating genetic distance against the fossil record, a transversion-based sequence divergence of 0.22% (+/-0.015%) per million years is proposed for cytochrome b clock calibrations in the Bovidae. All evidence suggests that the Alcelaphini form a monophyletic group; there was no support for the recognition of the Lichtenstein's hartebeest in a separate genus (Sigmoceros), and the acceptance of the previously suggested Alcelaphus is recommended for this species. High bootstrap support was found for a sister taxon relationship between Alcelaphus and Damaliscus, a finding which is in good agreement with allozyme and morphological studies. In the case of the Tragelaphini, the molecular data suggest the inclusion of Taurotragus in the genus Tragelaphus, and no genetic support was found for the generic status of Boocercus. Although associations within the Antilopinae (comprising the tribes Neotragini and Antilopini) could not be unequivocally resolved, there was nonetheless convincing evidence of non-monophyly for the tribe Neotragini, with the Suni antelope (Neotragus moschatus) grouping as a sister taxon to the Impala (Aepyceros melampus, tribe indeterminate, sensu Gentry, 1992) and the Klipspringer (Oreotragus oreotragus) falling within the duiker antelope tribe (Cephalophini).
We develop a stochastic version of a previously discussed model of optimal herd size selection in ungulates. We assume that a large herd size confers to the animals a high level of protection against predators, but reduces the amount of food which can be eaten by each individual; on the contrary animals belonging to small herds would have access to large amounts of food but would bear a high risk of being killed by predators. Employing a dynamic programming approach we analyze the optimal trade-off between starvation and predation risks under the hypothesis that the animals would try to maximize their expected reproductive fitness during the incoming breeding period. We compare the optimal strategy in environments described by different kinds of stochastic food distributions (including the deterministic limit) for different values of predation pressure and of overall food availability. We obtain general information about the effect of the level of randomness of food distribution on the mean individual fitness and on the number of reproducers (the animals which survive to the beginning of the reproductive season). Moreover we discuss how a certain number of behavioral and ecological processes--which have been often described in natural populations of ungulates and which are usually explained in terms of phenological variations of the ecological landscape--may be interpreted as caused by intrinsic variations of the animals' strategy.
The genus Pestivirus of the family Flaviviridae comprises four species, namely Bovine viral diarrhea virus-1 (BVDV-1), BVDV-2, Border disease virus (BDV), and Classical swine fever virus (CSFV). Comparative analyses of partial sequences have suggested that pestivirus isolates from giraffe (Giraffe-1) and reindeer (Reindeer-1) are distinct from the established species (Becher et al., Virology 262, 64--71, 1999). In this study, we report the complete genomic sequences of pestivirus strains Giraffe-1 and Reindeer-1. Comparative sequence analyses revealed considerable differences among Giraffe-1, Reindeer-1, and the currently recognized pestivirus species. Phylogenetic analysis of the complete coding sequences of these two strains, along with 13 other sequences representing the four established species, indicated that CSFV, BDV, and Reindeer-1 have bifurcated from one common branch and BVDV-1 and BVDV-2 from another. In the former branch BDV and the pestivirus from reindeer are more similar to each other than to CSFV. The giraffe pestivirus is equally distinct from both major branches. In addition, the antigenic relatedness of pestivirus isolates covering the observed major genetic groups was studied by cross-neutralization assays. A clustering procedure on the basis of antigenic differences indicated the presence of six major groups corresponding to the genetically defined groups. Taken together, the results of our analyses addressing both nucleotide sequence relatedness and serological relatedness argue for the inclusion of Giraffe-1 and Reindeer-1 as the first members of two separate novel species within the genus Pestivirus.
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Human milk contains large amounts of many oligosaccharides, most of which are fucosylated; several inhibit pathogenic bacteria, viruses, and toxins that cause disease in humans. Although bovine milk is known to have much less and many fewer types of oligosaccharides, no studies heretofore have indicated whether the amount or complexity of human milk oligosaccharides is unique to our species. Toward this end, a comparison was made of the major individual oligosaccharides in milk specimens from a variety of species, including the great apes. The neutral compounds, which represent the bulk of oligosaccharides in human milk, were isolated, perbenzoylated, resolved by high performance liquid chromatography (HPLC), and detected at 229nm. Ambiguous structures were determined by mass spectrometry. All milk specimens contained lactose, although levels were quite low in bear and kangaroo milk. The types of oligosaccharides in milk specimens from the primates resembled those of human milk, but the amounts, especially of the larger molecules, were markedly lower. The relative amounts of oligosaccharides in the bonobo changed over the course of lactation, as they do in humans. Marine mammals generally had few oligosaccharides in their milk other than 2'-fucosyllactose. Grizzly and black bear milk specimens contained a wide range of oligosaccharides, many of which had novel, fucosylated structures. Milk specimens from humans, bears, and marsupials had the greatest quantity of, and the most complex, neutral oligosaccharides. Although human milk contained more oligosaccharide than did milk specimens from the other species studied, the presence of appreciable amounts of complex oligosaccharides was not unique to humans. This finding suggests that in animal milk specimens, as in human milk, neutral fucosylated oligosaccharides potentially offer protection from pathogens to offspring with immature immune systems.
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High congruence, support, stability, resolution and decisiveness are seen as positive attributes by many systematists. Within a cladistic context, the consistency index, the retention index, branch support, data decisiveness, the number of nodes resolved in a strict consensus tree and the incongruence length difference are direct measures of these qualities. Phylogenetic analyses of 29 datasets for cetartiodactyl mammals show that for a particular character partition, these indices can vary radically in separate versus combined analysis of datasets. The quality of any single dataset is of little importance in comparison to a thorough sampling of the available character space.
The location and frequency of Ag-stained NORs and sites of rDNA hybridization were studied in the chromosomes of the South American camelids. In the four camelids these regions occur distally on chromosomes 18, 21, and 27 and the smallest biarmed elements. Quantitative analysis of NOR distribution showed variations between both cells and species. In llama, guanaco and alpaca the NORs number averaged 6 per cell, this being higher than in vicuña where the average was 3. Relative frequencies of NOR-bearing chromosomes in the four camelids were similar. Yet, in vicuña virtual absence of NOR sites on one of the smallest biarmed pairs was observed. The rDNA sites assessed in llama and vicuña by in situ hybridization with cloned 18S DNA were coincident with the NOR locations and with the frequencies characteristics for each species. Moreover, varying the exposure time of the autoradiographs, labeling patterns specific for each camelid were observed. Grain counts on individual chromosomes indicated that under our conditions one month exposure is enough to demonstrate all the rDNA sites available in the complement of llama. Conversely, at least two months are necessary to show the total sites existing in vicuña. Most probably this finding reflects the presence of variations in the amount of copies of the ribosomal genes per chromosome.
The DNA composition and the in situ hybridization of satellite fractions were analysed in the New World camelids llama, alpaca, guanaco and vicuña. In the four camelid forms, it was possible to identify a similar main band DNA and five satellite fractions (I-V) with G + C base contents ranging from 32% to 66%. Satellites II-V from llama were in situ reannealed on chromosomes from the four camelid forms. The results obtained were: (a) the four satellites hybridized with regions of C-banding (centromeric regions of all chromosomes and short arms of some autosomes); (b) in general, homologous hybridizations (llama DNA versus llama chromosomes) were more efficient than heterologous reassociations; there were however three exceptions to this rule (vicuña and alpaca satellite fraction II, chromosome group B; vicuña fraction V, chromosome groups A and B); (c) X chromosomes from the four camelids had satellites III-V but lacked satellite II, (d) no satellite fraction was detected on chromosome Y. The analysis of the in situ hybridization patterns allowed to conclude that most or all C-banded chromosome regions comprise several satellite DNA fractions. It is, moreover, proposed that there is an ample interspecies variation in the number of chromosomes that cross-react with a given satellite fraction. Our data give further support to the close genomic kinship of New World camelids.