Hepatocellular carcinoma in a squirrel monkey (Saimiri sciureus)

Abstract: A well-differentiated hepatocellular carcinoma of the liver was diagnosed in a female squirrel monkey. The lesion showed trabecular, solid and glandular features that are characteristics of malignant liver tumours.     

Copy number variants (CNVs) in primate species using array-based comparative genomic hybridization

A substantial amount of genomic variation is now known to exist in humans and other primate species. Single nucleotide polymorphisms (SNPs) are thought to represent the vast majority of genomic differences among individuals in a given primate species and comprise about 0.1% of the genomes of two humans. However, recent studies have now shown that structural variation msay account for as much as 0.7% of the genomic differences in humans, of which copy number variants (CNVs) are the largest component. CNVs are segments of DNA that can range in size from hundreds of bases to millions of base pairs in length and have different number of copies between individuals. Recent technological advancements in array technologies led to genome-wide identification of CNVs and consequently revealed thousands of variable loci in humans, comprising as much as 12% of the human genome [A.J. Iafrate, L. Feuk, M.N. Rivera, M.L. Listewnik, P.K. Donahoe, Y. Qi, S.W. Scherer, C. Lee, Nat. Genet. 36 (2004) 949–951, [3]]. CNVs in humans have already been associated with susceptibility to certain complex diseases, dietary adaptation, and several neurological conditions. In addition, recent studies have shown that CNVs can be successfully implemented in population genetics research, providing important insights into human genetic variation. Nevertheless, the important role of CNVs in primate evolution and genetic diversity is still largely unknown. This article aims to outline the strengths and weaknesses of current comparative genomic hybridization array technologies that have been employed to detect CNV variation and the applications of these techniques to primate genetic research.     

Developmental genetic profiles of glutamate receptor system,neuromodulator system,protector of normal tissue and mitochondria,and reelin in marmoset cortex: Potential molecular mechanisms of pruning phase of spines in primate synaptic formation process during the end of infancy and prepuberty (II)

This is the second report of a series paper, which reports molecular mechanisms underlying the occurrence of pruning spine phase after rapid spinogenesis phase in neonates and young infant in the primate brain. We performed microarray analysis between the peak of spine numbers [postnatal 3 months (M)] and spine pruning (postnatal 6 M) in prefrontal, inferior temporal, and primary visual cortices of the common marmoset (Callithrix jacchus). The pruning phase is not clearly defined in rodents but is in primates including the marmoset. The differentially expressed genes between 3 M and 6 M in all three cortical areas were selected by two-way analysis of variance. The list of selected genes was analyzed by canonical pathway analysis using “Ingenuity Pathway Analysis of complex omics data” (IPA; Ingenuity Systems, Qiagen, Hilden, Germany). In this report, we discuss these lists of genes for the glutamate receptor system, G-protein-coupled neuromodulator system, protector of normal tissue and mitochondria, and reelin. (1) Glutamate is a common neurotransmitter. Its receptors AMPA1, GRIK1, and their scaffold protein DLG4 decreased as spine numbers decreased. Instead, GRIN3 (NMDA receptor) increased, suggesting that strong NMDA excitatory currents may be required for a single neuron to receive sufficient net synaptic activity in order to compensate for the decrease in synapse. (2) Most of the G protein-coupled receptor genes (e.g., ADRA1D, HTR2A, HTR4, and DRD1) in the selected list were upregulated at 6 M. The downstream gene ROCK2 in these receptor systems plays a role of decreasing synapses, and ROCK2 decreased at 6 M. (3) Synaptic phagosytosis by microglia with complement and other cytokines could cause damage to normal tissue and mitochondria. SOD1, XIAP, CD46, and CD55, which play protective roles in normal tissue and mitochondria, showed higher expression at 6 M than at 3 M, suggesting that normal brain tissue is more protected at 6 M. (4) Reelin has an important role in cortical layer formation. In addition, RELN and three different pathways of reelin were expressed at 6 M, suggesting that new synapse formation decreased at that age. Moreover, if new synapses were formed, their positions were free and probably dependent on activity.     

Developmental expression profiles of axon guidance signaling and the immune system in the marmoset cortex: Potential molecular mechanisms of pruning of dendritic spines during primate synapse formation in late infancy and prepuberty (I)

The synapse number and the related dendritic spine number in the cerebral cortex of primates shows a rapid increase after birth. Depending on the brain region and species, the number of synapses reaches a peak before adulthood, and pruning takes place after this peak (overshoot-type synaptic formation). Human mental disorders, such as autism and schizophrenia, are hypothesized to be a result of either too weak or excessive pruning after the peak is reached. Thus, it is important to study the molecular mechanisms underlying overshoot-type synaptic formation, particularly the pruning phase.     

Evolution of Mhc–DRB Introns: Implications for the Origin of Primates

Introns are generally believed to evolve too rapidly and too erratically to be of much use in phylogenetic reconstructions. Few phylogenetically informative intron sequences are available, however, to ascertain the validity of this supposition. In the present study the supposition was tested on the example of the mammalian class II major histocompatibility complex (Mhc) genes of the DRB family. Since the Mhc genes evolve under balancing selection and are believed to recombine or rearrange frequently, the evolution of their introns could be expected to be particularly rapid and subject to scrambling. Sequences of intron 4 and 5 DRB genes were obtained from polymerase chain reaction-amplified fragments of genomic DNA from representatives of six eutherian orders—Primates, Scandentia, Chiroptera, Dermoptera, Lagomorpha, and Insectivora. Although short stretches of the introns have indeed proved to be unalignable, the bulk of the intron sequences from all six orders, spanning >85 million years (my) of evolution, could be aligned and used in a study of the tempo and mode of intron evolution. The analysis has revealed the Mhc introns to evolve at a rate similar to that of other genes and of synonymous sites of non-Mhc genes. No evidence of homogenization or large-scale scrambling of the intron sequences could be found. The Mhc introns apparently evolve largely by point mutations and insertions/deletions. The phylogenetic signals contained in the intron sequences could be used to identify Scandentia as the sister group of Primates, to support the existence of the Archonta superorder, and to confirm the monophyly of the Chiroptera. Received: 26 October 1998 / Accepted: 21 December 1998     

Accelerated Evolution of Cytochrome b in Simian Primates: Adaptive Evolution in Concert with Other Mitochondrial Proteins?

We have sequenced the cytochrome b gene of Horsfield's tarsier, Tarsius bancanus, to complete a data set of sequences for this gene from representatives of each primate infraorder. These primate cytochrome b sequences were combined with those from representatives of three other mammalian orders (cat, whale, and rat) in an analysis of relative evolutionary rates. The nonsynonymous nucleotide substitution rate of the cytochrome b gene has increased approximately twofold along lineages leading to simian primates compared to that of the tarsier and other primate and nonprimate mammalian species. However, the rate of transversional substitutions at fourfold degenerate sites has remained uniform among all lineages. This increase in the evolutionary rate of cytochrome b is similar in character and magnitude to that described previously for the cytochrome c oxidase subunit II gene. We propose that the evolutionary rate increase observed for cytochrome b and cytochrome c oxidase subunit II may underlie an episode of coadaptive evolution of these two proteins in the mitochondria of simian primates. Received: 15 December 1997 / Accepted: 24 February 1998     

Thermoregulatory responses to variations of photoperiod and ambient temperature in the male lesser mouse lemur: a primitive or an advanced adaptive character?

The lesser mouse lemur, a small Malagasy primate, is exposed to strong seasonal variations in ambient temperature and food availability in its natural habitat. To face these environmental constraints, this nocturnal primate exhibits biological seasonal rhythms that are photoperiodically driven. To determine the role of daylength on thermoregulatory responses to changes in ambient temperature, evaporative water loss (EWL), body temperature (T _b) and oxygen consumption, measured as resting metabolic rate (RMR), were measured in response to ambient temperatures ranging from 5 °C to 35 °C, in eight males exposed to either short (10L:14D) or long (14L:10D) daylengths in controlled captive conditions. In both photoperiods, EWL, T _b and RMR were significantly modified by ambient temperatures. Exposure to ambient temperatures below 25 °C was associated with a decrease in T _b and an increase in RMR, whereas EWL remained constant. Heat exposure caused an increase in T _b and heat loss through evaporative pathways. Thermoregulatory responses to changes in ambient temperature significantly differed according to daylength. Daily variations in T _b and EWL were characterized by high values during the night. During the diurnal rest, lower values were found and a phase of heterothermia occurred in the early morning followed by a spontaneous rewarming. The amplitude of T _b decrease with or without the occurrence of torpor (T _b < 33 °C) was dependent on both ambient temperature and photoperiod. This would support the hypothesis of advanced thermoregulatory processes in mouse lemurs in response to selective environmental pressure, the major external cue being photoperiodic variations. Accepted: 4 August 1998     

Ultrastructural identification of a new cell type — the N-cell as the source of neurotensin in the gut mucosa

The neurotensin-cell is identified immunohistochemically and ultrastructurally by differential counting of endocrine cells in the gut of a primate (Tupaia belangeri). Utilizing light microscopy, the EC-cells are identified by the Masson-Fontana silver stain; with the same method the neurotensin cells are not stained. The other endocrine cells have been quantified in the small intestine using the peroxidase-antiperoxidase stain with antisera against glucagon, somatostatin, cholecystokinin, gastrin, secretin, pancreatic polypeptide, gastric inhibitory peptide and neurotensin. In the ileal mucosa of Tupaia, the most frequent endocrine cell is the EC-cell followed by the glucagonoid cell, (L-cell). The immunoreactive neurotensin cell represents the third most frequent endocrine cell in this region. On the ultrastructural level, this third most frequent endocrine cell is a heretofore undescribed cell, the N-cell, containing electron dense secretory granules measuring 335 +/- 87 nm in diameter.