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156 records · Page 9Linked to original sources
PubMed2004

Isolation of Cryptococcus neoformans in Antwerp Zoo's nocturnal house.

Cryptococcosis was diagnosed postmortem in a striped grass mouse (Lemniscomys barbarus) housed in the nocturnal department of Antwerp Zoo. Eight of the remaining mice in the cage were captured. Cryptococcus neoformans was isolated from the lung of one animal. Two mice had an elevated serum cryptococcal antigen titre. On examination of the pooled faecal samples collected from 17 animal species housed in 23 cages of the nocturnal department, the pathogenic yeast was isolated from the faeces of the striped grass mice and a degu (Octodon degus). Numerous Cr. neoformans colonies were isolated from a tree-trunk, tree-stumps, and decaying wood collected from a hollow tree used to decorate the animals cage. Subsequent examination in four other cages of the nocturnal department revealed that all the sampled tree-trunks were colonized by Cr. neoformans. The fungus was isolated from the air sampled in the cage of the degu. Air samples collected in the public and service corridors remained negative. All the isolated strains were identified as Cr. neoformans var. neoformans serotype A.

Animals↗
PubMed1977

Diabetic cataracts and flavonoids.

Oral administration of quercitrin, an inhibitor of aldose reductase, leads to a significant decrease in the accumulation of sorbitol in the lens of diabetic Octodon degus. The onset of cataract is effectively delayed when quercitrin is continuously administered. Thus in these diabetic animals, as in galactosemic rats, the use of an effective aldose reductase inhibitor impedes the course of cataract development. These observations support the hypothesis that in diabetes, as in galactosemia, aldose reductase plays a key role in initiating the formation of lens opacity.

Alcohol Oxidoreductases↗
PubMed2004

Pubertal development of sex differences in circadian function: an animal model.

UNLABELLED: The development of adult circadian function, particularly sexual dimorphism of function, has been well studied only in rapidly developed rodents. In such species development is complete by weaning. Data from adolescent humans suggest that significant development occurs during the pubertal period. We hypothesized that a more slowly developing rodent might better mimic the changes in circadian function around puberty in humans and allow us to determine the underlying neural changes. Entrained and free-running circadian rhythms were analyzed and correlated with pubertal development in male and female Octodon degus (degu) that remained gonadally intact or were gonadectomized at weaning. Brains were collected during development to measure androgen and estrogen receptors in the suprachiasmatic nuclei (SCN) Adult circadian period does not develop until 10-12 months of age in degus, long after the onset of gonadal maturation (3-5 months). The timing of circadian period maturation correlates with the appearance of steroid receptors in the SCN. Changes in free-running rhythms only occurred in gonadally intact degus. Adult phase angles of activity onset develop between 2 and 3 months of age (comparing results of two experiments), soon after the onset of pubertal changes. CONCLUSION: The development of sexually dimorphic adult circadian period occurs after gonadal puberty is complete and requires the presence of gonadal steroids. The delay in development until after gonadal puberty is likely due to the delayed appearance of steroid receptors in the SCN. Phase is not sexually dimorphic and changes in the absence of steroid hormones.

Age Factors↗
PubMed2003

Seasonal acclimatization in water flux rate, urine osmolality and kidney water channels in free-living degus: molecular mechanisms, physiological processes and ecological implications.

The environmental modification of an organism's physiology in the field is often hypothesized to be responsible for allowing an organism to adjust to changing biotic and abiotic environmental conditions through increases in biological performance. Here, we examine the phenotypic flexibility of water flux rate, urine osmolality and the expression of kidney aquaporins (AQP; or water channels) in free-ranging Octodon degus, a South American desert-dwelling rodent, through an integrative study at cellular, systemic and organismal levels. Water flux rates varied seasonally and were significantly lower in austral summer than in winter, while urine osmolality was higher in summer than during winter. The observed water influx rate during summer was 10.3+/-2.3 ml day(-1) and during winter was 40.4+/-9.1 ml day(-1). Mean urine osmolality was 3137+/-472 mosmol kg(-1) during summer and 1123+/-472 mosmol kg(-1) during winter. AQP-2 medullary immunolabeling was more abundant in the kidneys of degus captured during summer than those captured during winter. This immunoreactivity was higher in apical cell membranes of medullary collecting ducts of degus in summer. AQP-1 immunostaining did not differ between seasons. Consistently, AQP-2 protein levels were increased in medulla from the summer individuals, as judged by the size of the 29 kDa band in the immunoblot. Here, we reveal how the integration of flexible mechanisms acting at cellular, systemic and organismal levels allows a small desert-dwelling mammal to cope with seasonal water scarcity in its semi-arid habitat.

Acclimatization↗
PubMed2004

Gametogenesis and nucleotypic effects in the tetraploid red vizcacha rat, Tympanoctomys barrerae (Rodentia, Octodontidae).

Nucleotypic effects link DNA content with nuclear size and cell dimensions of reproductive cells in polyploid organisms. We studied the gametogenesis of the allotetraploid rodent Tympanoctomys barrerae, aiming to determine these effects in reproductive cells. The species' cofamily members, Octodon degus and Spalacopus cyanus were used as control. Spermatogenesis and oogenesis in T. barrerae follows the pattern of differentiation and sequence of events of the control species, but varied nucleotypic effects were observed. Exceedingly large, spatulated spermatozoa with a submedially attached flagellum are characteristic of male T. barrerae. The diameter of the nuclei of primordial and growing follicles as well as those of the Graaff follicles, of the granulose, and of luteal cells are significantly larger and heavily heterochromatic. Moreover, the width of the pellucid zone is 108% thicker in T. barrerae than in S. cyanus. Binucleation was recorded in 26% of luteal bodies examined whereas no binucleated cells are detected in the diploid control. Likewise, large heterochromatic nucleoli were observed in the follicle cells but not in S. cyanus. This finding and the high heterochromatin content of reproductive cells in the red vizcacha rat is probably associated with its genome complexity so that redundant genetic information is silenced through heterochromatinization.

Animals↗
PubMed1987

Epidemiology of Chagas' disease in northern Chile: isozyme profiles of Trypanosoma cruzi from domestic and sylvatic transmission cycles and their association with cardiopathy.

Trypanosoma cruzi was isolated from 98 patients, 59 Triatoma infestans, 51 Triatoma spinolai, and 1 Octodon degus from northern Chile. With few exceptions, stocks originating from domestic hosts were classified, based on their isozyme profile, as principal zymodeme (Z)2, while sylvatic stocks from T. spinolai and the rodent O. degus showed Z1 profiles. These results indicate the existence of separate domestic and sylvatic transmission cycles. Clinical data and T. cruzi isozyme profiles from 107 chronic Chagas' disease patients showed no association between infecting T. cruzi zymodeme and the prevalence of chagasic cardiopathy. However, the age distributions of two groups of patients carrying different zymodemes were significantly different.

Adolescent↗
PubMed2005

Short report: Trypanosoma cruzi infection in wild mammals from a chagasic area of Chile.

We report results of PCR-DNA based detection of Trypanosoma cruzi in wild mammal reservoirs from a chagasic area of Chile. We analyzed 157 blood samples from wild mammals including the marsupial Thylamis elegans and the rodents Octodon degus, Phyllotis darwini, and Abrothrix olivaceus. In addition, 42 blood samples from goats (i.e., a peridomestic mammal) were analyzed. Blood samples were used to extract DNA, and PCR was performed using the amplification of minicircle DNA sequences. Southern analysis was used to confirm diagnosis with a universal probe of P(32)-labeled kinetoplast DNA. Altogether, 51% of the wild and 36% of the peridomestic mammals were infected with T. cruzi. These findings suggest that the real T. cruzi infection levels in wild and peridomiciliary reservoirs are higher than those previously determined with serological and parasitological conventional methods. The relevance of our results is discussed in term of the risk factor of infection in human.

Animals↗
PubMed1984

Gas chromatographic analysis of lens monosaccharides.

Gas-liquid chromatography was employed to determine free monosaccharides in human, rat, and South American rodent Octodon degu lenses. In addition to D-glucose, D-fructose, sorbitol and myo-inositol, which were previously known to be components of lens tissue, glycerol, erythritol, threitol, ribitol, xylitol, and mannitol were also detected in the lenses of these three species. The concentrations in lenses of these three species were in the following ranges: glycerol 1.2 to 40 mumol/gm wet tissue; myo-inositol 4 to 25; and glucose, fructose, and remaining alditols 0.01 to 1.4/mumol/gm. The method is described and its applicability to analyses of free monosaccharides in other animal tissues is discussed.

Animals↗
PubMed2004

Hearing in coruros (Spalacopus cyanus): special audiogram features of a subterranean rodent.

Learning curves and behavioural audiograms of subterranean, socially living coruros (Spalacopus cyanus) were obtained using a positive reinforcement conditioning procedure. The individually varying audiograms revealed best hearing at frequencies between 1.25 and 1.6 kHz, which corresponds with the common pattern established in subterranean rodents studied so far. However, the broad hearing range covering frequencies at least between 0.25 and 20 kHz coupled with the high sensitivity (average minimum 7 dB) that is found in coruros are atypical features for audiograms of subterranean rodents, which usually show restricted high-frequency hearing ranges and very poor sensitivity. Hearing at low frequencies (peaks at frequencies <1 kHz), which may be related to sound transmission in underground burrows, and high sensitivity at 1.25/1.6 kHz are discussed in relation to vocalization. In addition to these peaks, a third peak at 8 kHz--probably a plesiomorphic feature of mammals--may be of significance in aboveground communication.

Acoustic Stimulation↗
PubMed2006

Lack of paternal care affects synaptic development in the anterior cingulate cortex.

Exposure to enriched or impoverished environmental conditions, experience and learning are factors which influence brain development, and it has been shown that neonatal emotional experience significantly interferes with the synaptic development of higher associative forebrain areas. Here, we analyzed the impact of paternal care, i.e. the father's emotional contribution towards his offspring, on the synaptic development of the anterior cingulate cortex. Our light and electron microscopic comparison of biparentally raised control animals and animals which were raised in single-mother families revealed no significant differences in spine densities on the apical dendrites of layer II/III pyramidal neurons and of asymmetric and symmetric spine synapses. However, significantly reduced densities (-33%) of symmetric shaft synapses were found in layer II of the fatherless animals compared to controls. This finding indicates an imbalance between excitatory and inhibitory synapses in the anterior cingulate cortex of father-deprived animals. Our results query the general assumption that a father has less impact on the synaptic maturation of his offspring's brain than the mother.

Animals↗
PubMed2007

Evaluation of a laryngoscope and a rigid endoscope for the examination of the oral cavity of small mammals.

The oral cavities of 65 rabbits, 35 chinchillas, 38 guinea pigs, 19 degus and 13 prairie dogs suffering from a lack of appetite, hypersalivation, moist dermatitis, swelling of the lower jaw or mild exophthalmos were examined with a paediatric laryngoscope and rigid endoscope. The laryngoscope was safe and satisfactory for a preliminary examination, but changes in the less accessible caudal parts of the cavity could not be identified precisely. A rigid endoscope with 30 degrees optics made it possible to examine all parts of the oral cavity and oropharynx, and make detailed observations of surface lesions on the premolar and molar teeth and the mucosal surface of the gingiva, tongue and hard palate; endoscopy with 70 degrees optics provided an excellent view of the occlusal tooth surfaces, tooth crowns, and buccal mucosa. The collection of biopsy samples, the removal of foreign objects and the correction of malocclusions were greatly simplified by the use of the endoscope owing to the clear visualisation of the procedures, and the risk of injury was minimised. The examinations with a laryngoscope were made effectively on animals that were manually restrained, but a thorough examination with a rigid endoscope required the animals to be anaesthetised.

Anesthesia↗