I examined male endocrinology and social bonds in relation to dominance status in four groups of wild white-faced capuchin monkeys, Cebus capucinus, in the Santa Rosa Sector of the Área de Conservación Guanacaste, Costa Rica. I used noninvasive monitoring of male fecal androgen and glucocorticoid levels to examine the hormonal correlates of dominance and rank acquisition. In spite of low rates of aggression among coresident males, alpha males had higher androgen (testosterone and dihydrotestosterone) levels than subordinate males. Among subordinates, adult males had higher androgen levels than subadult males. During a non-aggressive rank increase, the new alpha male’s androgen levels increased immediately after attainment of the alpha position, and continued to increase for several months thereafter, while glucocorticoid increases lagged behind. In contrast, a subordinate adult male in the group had no change in androgen or glucocorticoid levels. Female white-faced capuchins do not display behavioral estrus, and ovulation is not associated with any changes detectable to the human observer. Therefore, I inferred female reproductive status by analyzing fecal progesterone and estradiol. Alpha and subordinate males experienced androgen and glucocorticoid increases in the presence of fertile females, a period likely associated with increased sexual activity and competition among coresident males. Androgens and glucocorticoids were also higher in the dry season, when intergroup encounters were more frequent. High competition between groups may facilitate low rates of intragroup aggression and the formation of social bonds within groups. I found that coresident males formed differentiated social bonds, and formed stronger social bonds when they had fewer coresident males and when group sex ratio was male-biased. Alpha males had the weakest and least equitable bonds, while relationships among subordinate males were characterized by relatively strong and somewhat reciprocal grooming. The importance of male bonds, particularly among subadult males, may reflect the importance of coalitions of immigrant males in the ability to takeover social groups and increase dominance status. A meta-analysis of parallel dispersal – when conspecifics emigrate together or immigrate into groups containing familiar individuals - indicates that in male primates, this behavior may be linked with the propensity of males to form coalitions and the need to retain coalition partners. / acase@tulane.edu

Siglecs and CEA are two families of cell surface proteins belonging to the immunoglobulin superfamily. They are thought to be involved in cell-cell interactions and have various other biological functions. We used the GENECONV program that applies statistical tests to detect gene conversion events in each family of five primate species. For the Siglec family, we found that gene conversions are frequent between CD33rSiglec genes, but are absent between their conserved Siglec genes. For the CEA family, half of gene conversion events detected are located in coding regions. A significant positive correlation was found between the length of the conversions and the similarity of the converted regions only in the Siglec gene family. Moreover, we found an increase in GC-content and similarity in converted regions compared to non-converted regions of the two families. Furthermore, in the two families, gene conversions occur more frequently in the extracellular domains of proteins, and rarely in their transmembrane and cytoplasmic regions. Finally, these two families appear to be evolving neutrally or under negative selection.

This study examined population density and habitat use of a species of greater galago, genus Otolemur, around Mt. Kasigau, Kenya. Mt. Kasigau has a unique regional microclimate, a cloud forest, which provides many different flora and fauna a home. To examine population density, two different methods were used. The first method was using line transects and analyzing results using Distance 6.0. These surveys were conducted during both dry and wet season and results were compared after the study. The second method was to trap individuals and use mark-recapture to determine population density. When caught in a trap, individuals were also weighed and measurements were taken. Accurate weight was taken for 17 individuals; ear height, tail length, and hind foot length were recorded for 21 individuals. Mark-recapture data were analyzed using Krebs/WIN 3.0. Population density estimates using both methods were compared and provided similar results; Distance 6.0 estimated 0.62 individuals per hectare and Krebs/WIN 3.0 estimated 0.51 individuals per hectare. Morphological measurements were not consistent with published data of known species of Otolemur garnettii, which is the most common greater galago in East Africa. It is possible the Mt. Kasigau population is reproductively isolated and DNA analysis should be conducted in the future. Habitat usage of greater and lesser galagos and diurnal primates was examined to determine which tree species are commonly used by these individuals.

Over the past few decades, the dominant view by comparative psychologists of analogical reasoning in nonhuman primates was one of dichotomy between apes, including humans, and monkeys: the distinction between the analogical ape and paleological monkey (Thompson & Oden, 2000). Whereas evidence for analogy proper by representation reinterpretation in monkeys is sparse and debated, the gap between that which is analogic and paleologic has been narrowed by the studies presented here. Representation of relational concepts important for analogy proves difficult for rhesus and capuchin monkeys without the ability to rely on a greater amount of perceptual variability, implicating a perceptually-bound predisposition in problem-solving (Chapters 2-3). A shift in attention from perceptual features to abstract concepts for employment in relational matching is again difficult, but not impossible given cognitive incentive in the form of differential outcomes to refocus attention on conceptual properties (Chapter 4). Finally, chimpanzees unlike monkeys appear more apt to reason by analogy, perhaps due to a more default conceptual focus (Chapter 5). Taken together, these studies provide an account for the emergence of analogical reasoning skills throughout the primate lineage in contrast to views regarding analogy a hallmark of human intelligence.

Humans have a tendency to engage in economically irrational behaviors such as gambling, which typically leads to long-term financial losses. While there has been much research on human gambling behavior, relatively little work has been done to explore the evolutionary origins of this behavior. To examine the adaptive pressures that may have led to this seemingly irrational behavior in humans, nonhuman primates were tested to explore their reactions to gambling type scenarios. Several experiments based on traditional human economic experiments were adapted for use with a wider variety of primate species including chimpanzees and capuchin monkeys. This allowed for testing multiple species using similar methodologies in order to make more accurate comparisons of species abilities. This series of tasks helps to elucidate risky decision-making behavior in three primate species.

Three experiments were conducted to evaluate the relation between age, relative numerousness judgments, and summation in Western lowland gorillas. The findings indicated that most of the gorillas did not perform relative numerousness judgments until after specific training to do so. However, the gorillas did perform summation without specific training and an age-related difference was apparent.

The ability to recognize sameness among objects and events is a prerequisite for abstraction and forming concepts about what one has learned; thus, identity and nonidentity learning can be considered the backbone of higher-order human cognitive abilities. Discovering identity relations between the constituent properties of objects is an important ability that often characterizes the comparisons that humans make so it is important to devote attention to understanding how nonhuman primates process and conceptualize part-identity as well as whole-identity. Because the ability to generalize the results of learning is to what concepts ultimately reduce, the series of experiments herein first investigated responding to part-identity and -nonidentity and whole-identity and -nonidentity and then explored the generality of such learning to the formation of concepts about color, shape, and cardinal number. The data from Experiments 1, 2, and 3 indicated that the two orangutans learned to respond concurrently to color whole-identity and -nonidentity and they responded faster to color whole-identity. Additionally, both subjects learned to respond concurrently to color and shape part- and whole-identity and for the most part, it was easier for them to do so with color part- and whole-identity problems than shape part- and whole-identity problems. Further, their learned responses to color and shape part- and whole-identity fully transferred to novel color part-identity problems for both subjects and fully transferred to novel color and shape whole-identity problems for one orangutan. The data from Experiments 4, 5, and 6 showed that one subject learned to judge numerical identity when both irrelevant dimensions were cue-constant, but the subject did not do the same when one or more irrelevant dimensions were cue-ambiguous. Further, the subject's accuracy was affected by the numerical distance and the numerical total of comparisons during acquisition of the conditional discrimination. The subject subsequently formed a domain-specific concept about numerical identity as evinced by the transfer of learning to novel numerosities instantiated with novel, cue-constant element colors and shapes and novel numerosities instantiated with cue-constant, familiar element colors and shapes. Given the adaptive significance of using concepts, it is important to investigate if and how nonhuman primates form identity concepts for which they categorize or classify the stimuli around them. This dissertation provided evidence about the extent to which orangutans learned to respond to color, shape, and number identity and nonidentity and subsequent concept formation from such learning. The findings from this study will help in understanding the convergence and divergence in the expression abstraction in the primate phylogeny, thus, informing our understanding about the origins and mechanisms of cognition in human and nonhuman primates.

Reproduction de : Thèse de doctorat : Médecine. Sciences de la vie et de la santé. Immunologie - Virologie : Nantes : 2008. / Bibliogr.

Upon aging, the intervertebral disc (IVD) inevitably undergoes degeneration characterized by biochemical and morphologic changes. IVD degeneration can lead to multiple clinical disorders such as back and neck pain, and myelopathy. Low back pain can disable up to 85% of the adult population and results in a significant restriction of social activities and inability to work. Such disorder incurs billions of dollars in medical expenditures each year. Despite advances in the detection and treatment of the degeneration, the regeneration of the IVD remains low because current therapies are limited by exogenous curing approaches. New strategies for the reversal of IVD degeneration, including gene, cytokine, and stem cell therapies that can influence the anabolic and catabolic pathways in disc cells have been under investigation. These therapies aim to rejuvenate or replace diminished nucleus pulposus cells in the degenerative IVD. Recent reports have put forth a proposal of “endogenous disc stem cells”, suggesting that cells derived from the degenerative IVD tissue possess stem cell properties. These putative stem cells are believed to regulate the development and homeostasis of the IVD tissue. In this study, we identified and characterized a stem cell population from the IVD of healthy Rhesus monkey, termed disc stem/progenitor cells (DSCs). We show that the DSCs possess clonogenicity, multipotency and self-renewal capacity. The DSCs are phenotypically similar to bone marrow mesenchymal stem cells (BMSCs) but they are not identical. The DSCs show a faster growth rate under hypoxia than normoxia. DSCs derived from nucleus pulposus (DSCNP) show a stable expression level of hypoxia inducible factor-1 alpha (Hif-1ａ) in response to hypoxia. DSCs derived from annulus fibrosus (DSCAF) are more resistant to apoptosis under hypoxia than DSCNP. More importantly, small leucine-rich proteoglycans (SLRPs) are identified as important DSC niche components. We show that biglycan (bgn) and decorin (dcn) reduce the susceptibility of DSCs to hypoxia-induced apoptosis by promoting the expression of hypoxia inducible factors (HIFs). Our findings suggest that DSCs rely on the unique niche components for survival. In summary, our findings propose the existence of endogenous stem cells in IVD. Further study of the DSCs may provide new insights into the biology of IVD and facilitate the design of new strategies to treat disc degeneration in future. / published_or_final_version / Orthopaedics and Traumatology / Doctoral / Doctor of Philosophy

Se realizó el análisis bioquímico de sangre y orina y la biopsia renal mediante laparotomía o por método percutáneo en 15 primates de la especie Cebus apella y en 20 de la especie Saimiri boliviensis, clínicamente sanos y criados en cautiverio, así como el estudio histológico, inmunohistoquímico y ultraestructural de las biopsias. Se estudiaron riñones obtenidos en las necropsias de 17 Cebus apella y 50 Saimiri boliviensis, muertos por diversas causas. Los análisis bioquímicos de sangre y de orina en la especie Cebus apella permitieron determinar que los valores normales no se modificaron ante la existencia de lesiones renales leves, moderadas y severas, en tanto que en la especie Saimiri bolivie nsis existió relación entre lesiones renales severas y valores elevados de urea y creatinina séricas. Los métodos de biopsia seleccionados fueron apropiados, debido a que todos los animales se recuperaron sin complicaciones y el material obtenido fue adecuado para el estudio. La combinación de las técnicas histoquímicas, inmunohistoquímicas y el estudio ultraestructural permitió realizar el diagnóstico de las nefropatías de estos primates. Las mismas incluyeron glomerulonefritis, nefritis intertisciales y lesiones tubulares de diversa severidad. Las alteraciones glomerulares primarias se agruparon en glomerulonefritis mesangioproliferativas, proliferativas y membranosas, esclerosis y hialinosis glomerular en la mayoría de ellas se pudieron apreciar presentaciones difusas o focales y globales o segmentales. Los depósitos de Ig M tuvieron un patron de distribución mesangial y se correspondieron con las lesiones glomerulares caracterizadas por incremento de la matriz mesangial. Un elevado número de lesiones renales en las dos especies de primates, probablemente fueron consecuencia de procesos infecciosos ascendentes de las vías urinarias y, en menor proporción pudieron obedecer a complejos antígeno-anticuerpo circulantes de diversos orígenes. Las lesiones renales identificadas en el material de necropsia fueron similares a las observadas en las biopsias aunque en general resultaron más severas. / Blood and urine analysis and renal biopsias were accomplished in 15 healthy adult primates of the Cebus apella species and in 20 of the Saimiri boliviensis species bred in captivity.Biopsis were obtained at laparatomy or through the blind percutaneous techniques. Histological, histochemical, inmunohistochemical and ultrastructural study of the biopsies were performed. Kidneys obtained from necropsies of 17 Cebus apella and 50 Saimiri boliviensis dead from diverse causes were also included. In the C. apella, biochemical blood values and urine analysis results remained within the normal range in spite of the presence of subtle to severe renal lesions. In the S. boliviensis species, severe renal lesions resulted in elevated blood urea nitrogen and serum creatinine levels. The biopsy techniques were appropiate as all the anaimals recovered uneventfuly after the procedure and the samples obtained were adequate for the study. The combination of histochemical, inmunohistochemical and ultrasstructural study alloved to establish a diagnosis of the nephropaties. Glomerulonephritis, interstitial nephritis and tubular lesions with different severity were identified. The primary glomerular alterations were classified into mesangioproliferatie, rpoliferative, and membranous glomerulonephritis, sclerosis andgloerular hialinosis. In most of them focal or diffuse and global or segmental presentations could be appreciated. the deposits of Ig M had a mesangial distribution pattern and corresponded to the glomerular lesions characterized by an increase in the mesangial matrix. it is probable that most of the renal lesions recognized in both species were a consequence of ascending infections from the urinary tract and a smallerproportion were the results of circulating antigen-antibody complexes of various origins. Renal lesions recognized in necropsy samples were similar to those observed in biopsies, although they were more severe.