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At least 127 records · Page 7Linked to original sources
PubMed1989

Functional differentiation of long bones in lorises.

The external dimensions of the limb bones and the geometry of their midshaft cross-sections were determined for Loris tardigradus and Nycticebus coucang. Relative cortical thickness, cortical area, and second moment of area were calculated and contrasted with locomotor stresses. The difference in shape-related strength of the bones between the smaller- and the larger-bodied species is more pronounced than can be expected from stresses acting during normal locomotion. The Nycticebus skeleton has a much higher safety margin overall and seems to be dimensioned for infrequent but critical stresses of high magnitude. Lorisine gaits in general are characterized by low ground reaction forces, great mobility in all joints, and a nearly equal share in propulsion and weight-bearing by the fore- and hindlimb. Accordingly, the long bones of lorises (especially those of L. tardigradus) tend to be less rigid than those of other mammalian species (including other primates), they lack a preferential plane of higher bending strength, and femur and humerus do not differ markedly in their capacity to withstand mechanical stresses. External dimensions of the humerus and femur of the two African lorisine species parallel and corroborate these results. Some more general implications for the relationships between bone shape and locomotor stresses are also discussed.

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PubMed1993

Behaviour and reproduction of the slender loris (Loris tardigradus) in captivity.

Observations were made on the behaviour of a group of slender lorises (Loris tardigardus) maintained in the Adelaide Zoo. Descriptions of their individual behaviour, social interactions, reproductive biology and development of young are given. The slender loris displays a more complex social life-style than has previously been reported, with huddling, marking activities and the behavioural complex of stretching/wrestling/allogrooming occurring daily. Evidence of the formation of a female coalition is described for the first time for this species. The low reproductive success of the group may have been attributable to the mixing of two Sri Lanka subspecies. Matings between L. tardigradus grandis and L. tardigradus tardigradus produced one sibling that reached maturity but did not breed.

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PubMed1995

Karyotype polymorphism in the slender loris (Loris tardigradus).

Three wild-caught Sri Lankan and two captive-bred slender lorises (Loris tardigradus) in Adelaide Zoo, South Australia, were karyotyped from leucocyte cultures. The founder male and one of the founder females were of the grey subspecies L. tardigradus grandis, of which L. tardigradus nordicus is probably a synonym. The other founder female was a small red-brown L. tardigradus tardigradus. All three wild-caught individuals were karyotypically distinct from each other and their offspring showed the expected heterozygosity. The L. tardigradus tardigradus karyotype was no more distinct from the grey subspecies karyotypes than they were from each other. On present evidence, Indian and Sri Lanka lorises appear to be chromosomally distinct.

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PubMed1996

A biomechanical investigation into the absence of leaping in the locomotor repertoire of the slender loris (Loris tardigradus).

Unlike all other primates, members of the subfamily Lorisinae are never seen to leap. To investigate the anatomical specializations that are behind the absence of leaping in their locomotor repertoire, a predictive mechanical model of leaping was developed using the lesser bushbaby, Galago moholi, as a size-matched leaping prosimian comparison. This enabled the required limb movements for a leaping slender loris to be calculated, and hence the torque and power requirements at each of the hindlimb joints. From this information, the maximum feasible leap was calculated for the slender loris morphotype; and it was found that this alone would prevent the animal from leaping a greater distance than it could walk over, so that the reduction in fitness due to an apparent loss of leaping from the behavioural repertoire can be considered to be very small.

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PubMed2003

Redescription of Pterygodermatites (Mesopectines) nycticebi (Mönnig, 1920) (Nematoda: Rictulariidae), a parasite of slow loris Nycticebus coucang (Mammalia: Primates).

Pterygodermaties (Mesopectines) nycticebi (Mönnig, 1920) (Nematoda: Spirurida: Rictulariidae) is redescribed based on immature and mature adults collected from the stomach and small intestine at autopsy of a slow loris, Nycticebus coucang (Boddaert, 1785) (Mammalia: Primates), in a zoological garden in Japan. It is first demonstrated that male possesses a minute telamon and a left lateral pore in the preanal part of body. The cause of death of the slow loris is strongly surmised to be related to the nematode infection, which was apparently acquired under captivity in the zoological garden.

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PubMed2003

Histology of vermiform appendix-like organ in slow loris.

The vermiform appendix-like organ (VALO) of the slow loris was investigated for its histology and immunohistochemical characteristics. The VALO has a much thinner wall with flat folded mucosa and shallower crypts than the cecal mucosa, while cellular components and population of the mucosa were similar to those of the cecum. No coalescent lymph nodules were seen in the submucosa. Immunohistochemically 5-HT-positive cells in the crypts and CD3- and CD8-positive lymphocytes in the lymph nodules were shown in the VALO as well as in the cecum. These findings suggest that the VALO is a low-differentiated vermiform appendix of the slow loris.

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PubMed2001

Molecular evolution of GH in primates: characterisation of the GH genes from slow loris and marmoset defines an episode of rapid evolutionary change.

Pituitary growth hormone (GH), like several other protein hormones, shows an unusual episodic pattern of molecular evolution in which sustained bursts of rapid change are imposed on long periods of very slow evolution (near-stasis). A marked period of rapid change occurred in the evolution of GH in primates or a primate ancestor, and gave rise to the species specificity that is characteristic of human GH. We have defined more precisely the position of this burst by cloning and sequencing the GH genes for a prosimian, the slow loris (Nycticebus pygmaeus) and a New World monkey, marmoset (Callithrix jacchus). Slow loris GH is very similar in sequence to pig GH, demonstrating that the period of rapid change occurred during primate evolution, after the separation of lines leading to prosimians and higher primates. The putative marmoset GH is similar in sequence to human GH, demonstrating that the accelerated evolution occurred before divergence of New World monkeys and Old World monkeys/apes. The burst of change was confined largely to coding sequence for mature GH, and is not marked in other components of the gene sequence including signal peptide, 5' upstream region and introns. A number of factors support the idea that this episode of rapid change was due to positive adaptive selection. Thus (1) there is no apparent loss of function of GH in man compared with non-primates, (2) after the episode of rapid change the rate of evolution fell towards the slow basal level that is seen for most mammalian GHs, (3) the accelerated rate of substitution for the exons of the GH gene significantly exceeds that for introns, and (4) the amino acids contributing to the hydrophobic core of GH are strongly conserved when higher primate and other GH sequences are compared, and for coding sequences other than that coding for hydrophobic core residues the rate of substitution for non-synonymous sites (K(A)) is significantly greater than that for synonymous sites (K(S)). In slow loris, as in most non-primate mammals, there is no evidence for duplication of the GH gene, but in marmoset, as in rhesus monkey and man, the putative GH gene is one of a cluster of closely related genes.

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PubMed1980

The ultrastructure of tricresylphosphate poisoning in primates. 3. Studies on alterations in neuronal soma.

This report deals with the ultrastructural changes observed in neurons of the posterior root ganglion of slow loris (Nycticebus coucang) following administration of tricresylphosphate (TCP) 0.2 ml/kg body weight for 10 days. The observed changes involved the rough and smooth endoplasmic reticulum profiles, neurofilaments, Golgi complex as well as lipofuscin pigment. Nissl substance was markedly dispersed to the periphery of the neuron. Membranous profiles of the smooth endoplasmic reticulum were lost. Neurofilaments were markedly increased and manifested neurofibrillary tangles or else were scattered over the cytoplasm. Golgi complexes were dilated and there was a marked increase in lipofuscin. These observations suggest that TCP produces degenerative changes in the organelles of sensory neurons similar to those seen at the height of chromatolysis produced by mechanical interference in the dorsal root ganglia and other neurons.

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PubMed2001

Failure of the ILD to determine data combinability for slow loris phylogeny.

Tests for incongruence as an indicator of among-data partition conflict have played an important role in conditional data combination. When such tests reveal significant incongruence, this has been interpreted as a rationale for not combining data into a single phylogenetic analysis. In this study of lorisiform phylogeny, we use the incongruence length difference (ILD) test to assess conflict among three independent data sets. A large morphological data set and two unlinked molecular data sets--the mitochondrial cytochrome b gene and the nuclear interphotoreceptor retinoid binding protein (exon 1)--are analyzed with various optimality criteria and weighting mechanisms to determine the phylogenetic relationships among slow lorises (Primates, Loridae). When analyzed separately, the morphological data show impressive statistical support for a monophyletic Loridae. Both molecular data sets resolve the Loridae as paraphyletic, though with different branching orders depending on the optimality criterion or character weighting used. When the three data partitions are analyzed in various combinations, an inverse relationship between congruence and phylogenetic accuracy is observed. Nearly all combined analyses that recover monophyly indicate strong data partition incongruence (P = 0.00005 in the most extreme case), whereas all analyses that recover paraphyly indicate lack of significant incongruence. Numerous lines of evidence verify that monophyly is the accurate phylogenetic result. Therefore, this study contributes to a growing body of information affirming that measures of incongruence should not be used as indicators of data set combinability.

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PubMed1985

Derived morphology of the wrist articulations and theories of hominoid evolution. Part I. The lorisine joints.

The claim that lorisines possess wrist joint specialisations that parallel those in hominoids is refuted. The cautious, quadrupedal climbing lorisines therefore do not provide an adequate model for the locomotion of emergent hominoids, as has been suggested. The notion that the Hominoidea possess unique wrist joint synapomorphies facilitating an increased range of forearm supination, and correlated thereby with a capacity for suspensory forelimb locomotion, seems to be sustained. The lorisines do possess their own derived characters at the wrist, largely centred on the midcarpal joint, which accommodate an exaggerated habitual movement comprising ulnar deviation with extension and rotation of the sense of pronation; this produces the powerful pincer-like split hand. Rather similar but more extreme specialisations are described in schizodactylous marsupials. In all these specialised hands the habitual movement at the midcarpal joint appears to be merely an exaggeration of that occurring in the clasping type of hand found in the primitive therian mammals. This movement, about an axis running from dorsally on the radial side of the carpus with an angulation proximally towards the volar aspect on the ulnar side, apparently provided for adjustments in angulation between forearm and manus in the semi-sprawling gait of primitive non-cursorial therian mammals.

Animals↗
PubMed1982

Monomorphic anti-HLA-A,B,C monoclonal antibodies detecting molecular subunits and combinatorial determinants.

Thirteen monoclonal antibodies that react with monomorphic determinants on the HLA-A,B,C-beta 2-microglobulin (beta 2m) molecule were characterized. Analysis of antibody activity included inhibition by papain-solubilized HLA antigens and free beta 2m, antibody binding to mouse-human somatic cell hybrids containing human chromosome 6 or 15, and antibody cross-reactivity with lymphocytes from nonhuman species. Two criteria for monomorphism were established: 1) equal inhibition or absorption of antibody activity by all papain-solubilized HLA antigens or cell lines of different HLA specificities tested; and 2) nonpolymorphic cross-reactivity within another species or subspecies. On the basis of soluble antigen inhibition and binding to somatic cell hybrids, 3 classes of antibodies were detected: anti-beta 2m, anti-heavy chain, and anti-complex (against a combinatorial determinant formed by heavy chain and beta 2m). Antibody cross-reaction patterns in nonhuman species were suggestive that these monomorphic antibodies detect a limited number of determinants, minimally one on each chain and 2 combinatorial determinants. Examination of the known primary sequences for HLA-A2, HLA-B7, H-2Kb, and mouse, rabbit and human beta 2m provides a molecular explanation for this limited mouse anti-HLA monomorphic antibody activity.

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PubMed1981

The Langerhans cell.

In all mammalian species so far examined, Langerhans cells or their precursors are the only epidermal cells expressing Ia antigens or their equivalents. In man, xeno-antisera raised in rabbits against purified B-lymphocyte cell membrane antigens were utilized to stain the Langerhans cells by either fluorescent or immunoferritin methods. As high proportion of the indeterminate cells in the epidermis also expressed HLA-DR antigens, and a relationship to Langerhans cells is suggested. Confirmation of these results was obtained in mouse. Alloantisera raised against I-A and I-EC subregion products again stained only Langerhans cells. Fluorescent, immunoperoxidase, and immunoferritin methods were used and confirmation of the specificity of the reaction was achieved at the electron microscope level. Langerhans cells were shown by ATPase staining to be absent from the epithelium of the central cornea, but present in the limbus. Population of the entire corneal epithelium surface was induced by application of irritants or contact sensitizing agents such as DNCB. Grafting of corneas either deficient or populated with Langerhans cells, to skin beds, may answer the question of the influence of such cells on allograft rejection.

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PubMed1984

Quantitative studies of the evolution of the thalamus in primates.

A quantitative study of the thalamus and metathalamus has been carried out on brains of six different primate species. The allometric formula devised by Stephan, Bauchot and Andy (1970) has been slightly modified as two steps have been utilized in order to attain the required magnification of the final photomicrograph (a positive print, as opposed to Stephan et al's negative print). The thalamic and metathalamic structures are divided on the basis of their developmental stages into two groups--paleothalamus and neothalamus, so that their proportions to each other in primate phylogeny can be estimated. The results show that the neothalamus extends the paleothalamus by two-thirds (2/3rds) in Tupaia and by more than three-quarters (3/4ths) in Cercopithecus. Of all the thalamic groups, the dorsolateral thalamic nuclear group is most dominant in all primate species, except Tupaia, where the ventrolateral thalamic nuclei are larger than all other nuclei. The pulvinar is the most dominant nucleus in all species except Tupaia. These quantitative results conform, in most places, with the observations of other researchers, while they do not agree much with the qualitative observations of the thalamus in the same species (Simmons 1974). How this study has a bearing on the phylogenetic positions of the Tupaioidea and the Tarsioidea in the Primate Order, is briefly discussed.

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