Food avoidance learning in squirrel monkeys and common marmosets. (17/878)

Using a conditioned food avoidance learning paradigm, six squirrel monkeys (Saimiri sciureus) and six common marmosets (Callithrix jacchus) were tested for their ability to (1) reliably form associations between visual or olfactory cues of a potential food and its palatability and (2) remember such associations over prolonged periods of time. We found (1) that at the group level both species showed one-trial learning with the visual cues color and shape, whereas only the marmosets were able to do so with the olfactory cue, (2) that all individuals from both species learned to reliably avoid the unpalatable food items within 10 trials, (3) a tendency in both species for quicker acquisition of the association with the visual cues compared with the olfactory cue, (4) a tendency for quicker acquisition and higher reliability of the aversion by the marmosets compared with the squirrel monkeys, and (5) that all individuals from both species were able to reliably remember the significance of the visual cues, color and shape, even after 4 months, whereas only the marmosets showed retention of the significance of the olfactory cues for up to 4 weeks. Furthermore, the results suggest that in both species tested, illness is not a necessary prerequisite for food avoidance learning but that the presumably innate rejection responses toward highly concentrated but nontoxic bitter and sour tastants are sufficient to induce robust learning and retention.  (+info)

Magnetic cell sorting is a fast and effective method of enriching viable spermatogonia from Djungarian hamster, mouse, and marmoset monkey testes. (18/878)

Germ cell transplantation, which offers promising new approaches for research and clinical applications, has focused interest on spermatogonia. This paper describes a procedure that permits the isolation of large quantities of viable spermatogonia. The immunomagnetic isolation procedure was applied to testicular cell suspensions from photoinhibited and photostimulated Djungarian hamsters, mice, and marmoset monkeys. The cells were incubated with a polyclonal rabbit anti-c-kit IgG, binding of which was characterized by immunohistochemical staining. For magnetic labeling, a secondary anti-rabbit IgG conjugated to ferromagnetic microbeads was used. Separation columns allowed the retention of magnetically labeled cells within the matrix. The magnetic fractions were eluted after removal of the column from the magnetic field. All fractions were analyzed for cellular morphology and by flow cytometry. The final enrichment of c-kit-positive cells in the magnetic fraction using fully active testes was in the range of 25-55% with a viability rate of 80-90%. The magnetic fractions of all three species were characterized by high numbers of diploid cells. Cytological analysis revealed a strong enrichment of spermatogonia. No haploid cells were retained in the magnetic fraction. In comparison to conventional procedures, magnetic cell separation is an efficient and fast approach for isolation of spermatogonia.  (+info)

IgA-gliadin antibodies, IgA-containing circulating immune complexes, and IgA glomerular deposits in wasting marmoset syndrome. (19/878)

BACKGROUND: Marmosets in captivity are highly susceptible to wasting marmoset syndrome (WMS), the aetiology of which is still not fully determined. METHODS: The level of IgA-gliadin antibodies (IgA-AGA), of IgA-containing circulating immune complexes (IgA-CIC), and the degree of glomerular IgA deposits were compared between marmosets suffering from WMS and animals not affected by the disorder. RESULTS: Both IgA-AGA and IgA-CIC were demonstrable in all groups of monkeys investigated. IgA-AGA and IgA-CIC were significantly higher in monkeys with WMS than in non-affected animals. There was a significant correlation between the glomerular IgA-deposition and titre of IgA-AGA. The group of marmosets strongly positive for glomerular IgA deposits comprised significantly more animals suffering from WMS than the group without deposits. In the diet of the animals a considerable amount of gliadin-like cereal proteins was assayed. CONCLUSIONS: There are several parallels between the human disorders (coeliac disease and IgA-nephropathy/Berger's disease) and the changes observed in WMS. It should be further investigated if WMS in marmosets is a suitable animal model for both human diseases.  (+info)

Polymorphism in trypomastigotes of Trypanosoma (Megatrypanum) minasense in the blood of experimentally infected squirrel monkey and marmosets. (20/878)

Experimental infections by Trypanosoma (Megatrypanum) minasense were performed in primates - Saimiri sciureus and Callithrix penicillata - with the objective of searching for morphological variations of the blood trypomastigotes with respect to hosts and time of infection. We carried out morphological and morphometric analysis of blood trypomastigotes. Illustrations are given. Both the squirrel monkey and marmoset became infected after the injection of blood trypomastigotes of T. minasense, although the parasitaemia were briefer in the squirrel monkey. The parasites detected in the later host were narrower and shorter than those found in the inoculated marmoset. In the marmoset, the blood stream parasites derived from culture metacyclic trypomastigotes were considerably smaller than those derived from the inoculation of infected blood. Stronger evidence of polymorphism was found when, at the same time of infection, the blood trypomastigotes found in squirrel monkey had smaller length, body width and the distance from posterior end of the body to the kinetoplast almost four times smaller than the parasite found in the marmoset. Therefore, conflicting results on morphology and morphometry of T. minasense obtained by previous investigators could be due to polymorphism.  (+info)

Epstein-Barr virus lacking latent membrane protein 2 immortalizes B cells with efficiency indistinguishable from that of wild-type virus. (21/878)

Epstein-Barr virus (EBV) is a human herpesvirus that efficiently transforms and immortalizes human primary B lymphocytes. In this study, the role of latent membrane protein 2 (LMP2) in EBV growth transformation was investigated. LMP2 is a virally encoded membrane protein expressed in EBV-immortalized B cells previously shown to be nonessential for EBV transformation. However, a recent study reported that LMP2 may be an important determinant for efficient B cell transformation (Brielmeier et al., Journal of General Virology 77, 2807-2818, 1996). In this study a deletion mutation was introduced into the LMP2 gene using an E. coli mini-EBV construct containing sufficient EBV DNA to result in growth transformation of primary B cells. In an alternative approach, the introduction of the gene encoding the enhanced green fluorescent protein (EGFP) by homologous recombination into the LMP2 gene of EBV strain B95-8, generating the same LMP2 deletion mutation is reported. Careful quantification of B cell transformation using the EGFP+ LMP2- recombinant virus determined that in liquid culture medium or in culture medium containing soft agarose there was no difference in the ability of LMP2- virus to immortalize primary human B cells when compared to that of wild-type virus.  (+info)

The Old World monkey DAZ (Deleted in AZoospermia) gene yields insights into the evolution of the DAZ gene cluster on the human Y chromosome. (22/878)

The DAZ gene cluster on the human Y chromosome is a candidate for the Azoospermia Factor (AZFc). According to the current evolutionary model, the DAZ cluster derived from the autosomal homolog DAZL1 through duplications and rearrangements and is confined to Old World monkeys, apes and humans. To study functional and evolutionary aspects of this gene family we have isolated from a cynomolgus (Old World) monkey testis cDNA library the Y chromosomal cynDAZ and the autosomal cynDAZL1 cDNA. cynDAZL1 contains one DAZ repeat and displays high homology to human DAZL1. cynDAZ comprises 11 repeats, each consisting of exons 7 and 8, whereas the human DAZ cDNA repeat units contain predominantly exon 7. Genomic studies revealed the same amplific- ation events of a 2.4 kb genomic unit encompassing exons 7 and 8 in both species, indicating that after splitting of the two lineages, in the human mainly exon 8 was converted to a pseudoexon by splice site mutations. The structural features of cynDAZ reveal a more detailed model for the sequence of events leading to the present form of human DAZ. Thus, in a monkey species DAZ is present in a form more ancestral than that of the human. Studies on the immunolocalization of cynDAZ / DAZL1 in cynomolgus monkey testis revealed a biphasic expression pattern with proteins being detectable in A-pale to B-spermatogonia, late spermatocytes and spermatids, but not in early spermatocytes and late spermatids. In contrast, in the marmoset monkey, an animal lacking DAZ, DAZL1 protein was only expressed in late spermatocytes and early spermatids. These findings point to an additional function of cynDAZ / cynDAZL1 during spermato- genesis in the Old World monkey not needed in the New World monkey.  (+info)

Cutaneous receptive field organization in the ventral posterior nucleus of the thalamus in the common marmoset. (23/878)

The organization of cutaneous receptive fields in the ventroposterior (VP) thalamus of the common marmosets (Callithrix jacchus) was determined from single-unit recordings, and these data were correlated with the cytochrome oxidase (CO) histochemistry of the thalamus in the same animals. Under continuously maintained ketamine anesthesia, the receptive fields of a total of 192 single units were recorded from the right VP thalamus using 2 MOhms glass electrodes. After the receptive fields were mapped, the brains were reacted for CO histochemistry on 50-microm coronal frozen sections through the entire VP thalamus. The majority of units were localized to the CO-reactive regions that define the medial and lateral divisions of VP (VPm and VPl). Apart from the expected finding of the face being represented in VPm and the body in VPl, reconstructing the electrode tracks and unit locations in the histological sections revealed a general association between discrete regions of CO reactivity and the representation of specific body regions. Some low-threshold cutaneous units were apparently localized to VPi (the CO weak regions dorsal, ventral, and interdigitating with, the CO regions of VP). These VPi units were clearly part of the same representational map as the VPl and VPm units. We conclude that the low-threshold cutaneous receptive fields of the marmoset are organized in a single continuous representation of the contralateral body surface, and that this representation can most simply be interpreted as being folded or crumpled into the three-dimensional space of VP thalamus. The folded nature of the body map in VP may be related to the folded nature of VP as revealed by CO histochemistry.  (+info)

Implantation in the marmoset monkey: expansion of the early implantation site. (24/878)

This study was initiated to examine the early stages of trophoblast adhesion and invasion during implantation in the marmoset. Seven implantation sites were found in the uteri of four marmosets taken between days 13 and 15 of gestation. Three implantation sites in two uteri were examined in detail by electron microscopy. Between days 13 and 15, the marmoset implantation site expanded peripherally by adding areas where syncytial trophoblast penetrated between uterine luminal epithelial cells. Such penetrating masses often bridged openings of endometrial glands, shared junctional complexes with the uterine epithelial cells between which they are infiltrating, and subsequently reached the residual basal lamina of the uterine luminal epithelium. Centripetal to the peripheral region was an intermediate region in which syncytial trophoblast overlay individual clusters of epithelial cells and rested along the basal lamina. In this region there was some evidence of fusion of syncytial trophoblast with uterine epithelial cells. In the central region of the implantation site near the inner cell mass and amnion the trophoblast formed elaborate lamellipodia in relation to the basal lamina. In one of the three specimens examined with electron microscopy there were two foci where trophoblast penetrated through the basal lamina. It was also in the central region that trophoblast penetrated farthest into the uterine glands. The gland cells closest to trophoblast were less closely associated and lost their columnar shape, forming large round cells similar to the epithelial plaque cells of other primates. Where two blastocysts implanted on the same side of the uterus a conjoint membrane was formed which in regions consisted solely of syncytial trophoblast with two basal surfaces and two basal laminas. The prolonged period of time when the implantation site expands within the plane of the uterine epithelium (trophoblastic plate stage) and the peripheral to central sequence in extent of development make this primate a particularly useful animal for studies of trophoblast adhesion to and penetration of the uterine luminal epithelium.  (+info)