Seroprevalence for selected pathogens of zoonotic importance in wild nutria (Myocastor coypus)

Little information is present in the literature on diseases of the nutria (Myocastor coypus) in the wild. Serum samples obtained from 176 trapped animals were tested for antibody reactivity against 11 pathogens of significant zoonoses. Sera were positive against Leptospira (38.0 %, odds relative risk?=?0.03, Taylor series 95 % confidence limits 0.01–0.06), Toxoplasma gondii (27.8 %, odds relative risk?=?2.30, Taylor series 95 % confidence limits 1.23–4.31), Chlamydophila psittaci (21.0 % odds relative risk?=?4.94, Taylor series 95 % confidence limits 2.75–8.89), Streptococcus equi subspecies zooepidemicus (15.9 % odds relative risk?=?1.87, Taylor series 95 % confidence limits 1.04–3.37), and encephalomyocarditis virus (3.4 %, odds relative risk?=?0.05, Taylor series 95 % confidence limits 0.02–0.12). Some of the rodents showed antibodies at high titers, mostly indicating recent exposure. Seroprevalence rates varied among the location and age groups, although not by season or gender. All samples were seronegative for Brucella spp., Francisella tularensis, vesicular stomatitis virus, rabies virus, foot-and-mouth disease virus, and Encephalitozoon cuniculi.     

Giardia in beaver (Castor canadensis) and nutria (Myocastor coypus) from east Texas

We examined the prevalence of Giardia sp. infection in nuisance beaver (Castor canadensis) and nutria (Myocastor coypus) in east Texas. From October 1992 through September 1993, 100 beaver and 30 nutria were collected in routine wildlife management activities conducted by the U.S. Department of Agriculture-Animal and Plant Health Inspection Service-Texas Animal Damage Control Service. Fecal and duodenal mucoid samples were preserved from each animal. Fecal samples were examined for the occurrence of Giardia sp. cysts using the Merifluor immunoassay detection kit: 30 beaver (30.0%) and 20 nutria (66.7%) were positive for Giardia sp. Duodenal mucoid samples were examined for Giardia sp. trophozoites using trichrome staining. with 26 beaver (26.0%) and 20 nutria (73.3%) testing positive. Combining both techniques resulted in 33 beaver (33.0%) and 22 nutria (73.3%) testing positive for Giardia sp. We found no relationship between Giardia sp. and host age, sex, river system, habitat, county, or season in beaver. However, a relationship was found when season and habitat were considered together. No relationship was found between Giardia sp. and age, river system, habitat, county, or season in nutria: however, more males (87.5%) were infected than females (46.4%).     

Echinococcus multilocularis infection of a ring-tailed lemur (Lemur catta) and a nutria (Myocastor coypus) in a French zoo

Echinococcus multilocularis is a tapeworm responsible in its larval stage for alveolar echinococcosis, a disease which is lethal when left untreated. Multivesiculated parasitic lesions in the liver were diagnosed at necropsy in a captive-born nutria (Myocastor coypus) and in a ring-tailed lemur (Lemur catta) which had been in a French zoo for 16 months. Molecular analyses confirmed the diagnosis of E. multilocularis obtained by histological analyses. These were the first cases of infection by E. multilocularis reported in lemurs in Europe, and the first case in nutria in European enclosures. Lemurs are confirmed to be particularly sensitive to E. multilocularis with a massive infection. In both cases, the infection appears to have been contracted in the zoo indirectly via environmental contamination by feces from roaming foxes. Due to the large endemic area for E. multilocularis, the increasing prevalence in foxes in France, and an increase in awareness of the disease, other cases of infection in captive animals will probably be recorded in France in the coming years.     

Feeding strategy of coypu (Myocastor coypus) in central western France

The diet of coypu ( Myocastor coypus ) on two sites in a managed marsh was investigated by field observations and microscopic analysis of faeces. The habitat is mainly grazing pasture and over 51% of the plant fragments recovered from faeces were leaves of Graminaceae. Other food included hydrophytes, Cyperaceae, dicotyledons, flowers and seeds of Graminaceae and various roots. The mean annual diet of coypu was similar at both sites and showed moderate interannual variations. Relative proportions of different foods varied with season and availability. Hydrophytes, mostly Lemnaceae, were preferentially selected in late summer and autumn. Coypu fed on roots during winter, particularly in periods of exceptional food shortage due to flooding and severe frost. Even when crops were available, coypu utilized a wide range of food. The study shows the importance of feeding strategy in the ability of coypu to colonize new habitats, particularly those which are man-made.     

Adaptations to hypercapnic conditions in the nutria (Myocastor coypus)--in vivo and in vitro CO2 titration curves

Arterial blood acid-base status of unanesthetized, unrestrained nutria was studied during exposure to 5, 10 and 14.5% CO2 for 6 hr. Control values, pH = 7.426 +/- 0.037, PaCo2 = 36.5 +/- 3.1 mmHg and [HCO-3] = 24.3 +/- 2.5 mM/1 (n = 24), are within the normal range reported for other mammals. Values after 6 hr of exposure to 10% CO2 were: pH = 7.355 +/- 0.043, PaCO2 = 71.0 +/- 3.6 mmHg and [HCO-3] = 38.0 +/- 4.1 mM/l (n = 5). Arterial blood buffer slopes, obtained from the in vitro titration curve, did not show any pattern of adaptation to hypercapnia. Whole body buffer slopes, calculated from the in vivo CO2 titration curve, showed significantly higher values for the nutria than for the rat, dog and man, under comparable conditions [beta(delta HCO-3/delta pH)] = 57.0 slykes for nutria, 32.6 for rat and 11.8 for man. delta H+/delta PaCO2 = 0.38. mM/l/mmHg for nutria, 0.55 for rat and 0.76 for man. The results suggest that the nutria possesses an efficient metabolic mechanism for regulation of pH level during exposure to hypercapnic conditions.     

The role of the coypu (Myocastor coypus), an invasive aquatic rodent species,in the epidemiological cycle of leptospirosis: a study in two wetlands in the East of France

Leptospirosis is caused by pathogenic species of the Leptospira genus. Animals can have two roles in the epidemiological cycle: they can be an accidental host and suffer of the disease or a reservoir host which does not express any clinical sign and shed bacteria in their urine. Some of the most known reservoirs for leptospirosis are certain rodent species, but the situation is less clear for aquatic rodents, especially for coypu (Myocastor coypus). It has been shown that this species can have kidney carriage for leptospirosis, but the relationship between carriage and individuals or population health has not been investigated yet. We trapped 133 coypus in two wetlands in the East of France during 3 years. For each animal, a complete necropsy, leptospirosis serology, and a specific real-time quantitative PCR (qPCR) for pathogenic leptospires were performed; in addition, for some animals, a specific kidney culture for leptospires and histology on kidney were performed. In spite of a high seroprevalence (respectively 76 % and 64 %) and of a significant prevalence of kidney carriage in both areas (respectively 12.1 % and 8.0 % of positive qPCR on kidney), the trapped animals seemed in good health, and the population did not seem to be affected by the circulation of the bacteria. These findings are concurring arguments to consider coypu as a real reservoir for leptospirosis.     

Lung morphology in rodents (Mammalia, Rodentia) and its implications for systematics

A new nomenclature of the lung lobes and of the bronchial tree is presented, with which the lungs in 40 species of 11 rodent families are described. Whole, fixed lungs and silicone casts of the bronchial tree are tested for 23 characters, based on the distribution of lung lobes, the number and geometry of first order bronchi, the pulmonary blood supply, and lung symmetry. Ten lung morphotypes are recognized, seven of them representing one or more families: Castor type (Castoridae), Cryptomys type (Bathyergidae), Ctenodactylus type (Ctenodactylidae), Eliomys type (Gliridae), Myocastor type (Myocastoridae), Octodon type (Octodontidae and Echimyidae) and Rattus type (Sciuridae, Muridae pt. and Dipodidae). The Hydromys type is found only in Hydromys chrysogaster (Muridae), while Galea type A and B both appear in Galea musteloides (Caviidae). The data are phylogenetically analyzed by the program PAUP 4.0 using as outgroup Lagomorpha or Insectivora. On the species level, there are no well-resolved cladograms. On the family level, the cladograms do not contradict traditional rodent systematics with one exception: the Caviidae do not fall within Caviomorpha or even within the Hystricomorpha, but form a sister group to Dipodidae (Myomorpha). This appears to be a result of convergence. The lungs of Gliridae are more similar to those of Muridae than to those of Sciuridae. Included in the ingroup, Oryctolagus (Lagomorpha) forms a clade with Caviidae + Dipodidae. Thus, the "Glires hypothesis" is neither supported nor refuted.     

Chromosome studies in some members of the family Caviidae (Mammalia: Rodentia)

A study of the chromosomes of Cavia aperea and Galea musteloides has been made following the introduction into captivity of these two cavies from Argentina. The evolutionary relationships of the two genera have been considered, and the possible ancestry of C. porcellus from C. aperea was investigated in hybrids of the two species.     

Geomorphometric differences among four species of Microtus in Turkey (Mammalia: Rodentia)

In order to determine the phenotypic associations of four morphologically similar species of Microtus occurring in Turkey, we applied landmark-based shape analysis. The skulls of Microtus anatolicus, M. dogramacii, M. guentheri and M. levis (= M. rossiaemeridionalis) were found to differ significantly in terms of both size and shape. M. guentheri had the biggest skull, while M. levis had the smallest. Sexual dimorphism was found in the shape of the skull in M. dogramacii and M. levis. The tympanic bulla area is enlarged in M. anatolicus compared to the other species. Mahalanobis distances (the distance between a point and the group mean, taking into account the within-group covariance-variance matrix) confirm the distinction of the arvalis group (M. levis) and socialis group (Microtus anatolicus, M. dogramacii, M. guentheri).     

Changes in aquatic plant communitieson the island of Valaam due to invasion by the muskrat Ondatra zibethicus L.(Rodentia, Mammalia)

Muskrat invaded Valaam Island (Northern part of European Russia) in the 1970s. Aquatic plant communities of 1962 and 1993 were compared on the same plots. Quantitative changes were tested with the help of jack-knifing estimates of most known inventory (-) diversity indicators. Qualitative transformations were assessed using -diversity values. The results demonstrated substantially more discriminant ability of diversity measures than classical methods of mathematical statistics. All of the -diversity values declined synchronously without exception. Species composition also changed greatly and those species which turn out to be more resistant to muskrat grazing became the main dominant plants. The activity of Ondatra became the over-riding ecological factor connecting the littoral plant communities of the Valaam. It is concluded that the sustainability of this ecosystem was damaged by muskrat's invasion and that the role of muskrat should not be underestimated when studying the ecology of freshwater littoral communities.     

The Mercury Content and Antioxidant System in Insectivorous Animals (Insectivora,Mammalia) and Rodents (Rodentia,Mammalia) of Various Ecogenesis Conditions

This study is aimed at analyzing the total mercury in the tissues of mammals adapted to a semiaquatic or subterranean lifestyle and at analyzing the possible role of their antioxidant system in heavy metal detoxication. The water shrew Neomis fodiens Pennant, 1771, European mole Talpa europaea Linnaeus, 1758, muskrat Ondatra zibethicus Linnaeus, 1766, and water vole Arvicola terrestris Linnaeus, 1758 were the species under study. Our results indicate that mercury accumulation in the tissue depends on the age, tissue type, and diet of the species. The highest mercury content was recorded in water shrew tissues compared to other species. Age-dependent accumulation of the toxicant in the animals is reported. A correlation between mercury accumulation and catalase activity in the kidneys of the animals studied was found.     

Les chromosomes du rat de Cuming,Phloeomys cumingi Waterhouse, 1839 (Mammalia: Rodentia)

Résumé La formule chromosomique dePhloeomys cumingi est décrite pour la première fois. Le nombre diploïde est de 40 dans les deux sexes, le nombre fondamental de 60. Les 38 autosomes se répartissent en 5 paires de submétacentriques, 4 paires de métacentriques, 6 paires de grands acrocentriques et 4 paires de petits acrocentriques. Les chromosomes sexuels sont de grande taille et riches en hétérochromatine. L'analyse comparée des chromosomes dePhloeomys avec ceux deMus musculus et deRattus norvegicus permet de mettre en évidence de nombreuses analogies entre ces 3 espèces. II ressort de la comparaison des chromosomes dePhloeomys avec le caryotype ancestral des Cricetidae que onze paires de chromosomes au moins ont conservé le banding G originel. Bien que les données chromosomiques révèlent une parenté étroite entrePhloeomys et Muridae, elles n'excluent pas l'appartenance possible de cette espèce à une famille particulière, celle des Phloeomyidae.

---

The chromosome formula ofPhloeomys cumingi is described for the first time. The diploid number is 40 in both sexes, the fundamental number is 60. The 38 autosomes are divided into 5 pairs of submetacentrics, 4 pairs of metacentrics, 6 pairs of large acrocentrics and 4 pairs of small acrocentrics. The sex chromosomes are large and rich in C-positive heterochromatin. The comparative analysis of the chromosomes ofPhloeomys with those ofMus musculus andRattus norvegicus puts forward numerous analogies between these 3 species. According to the comparison of the chromosomes ofPhloeomys with the ancestral karyotype of the Cricetidae, eleven chromosome pairs at least have conserved their original G-banding pattern. Although chromosome data reveal a close relationship betweenPhloeomys and Muridae, they do not exclude the possible belonging of this species to a separate family, that of Phloeomyidae.

     

Some notes on reproduction in the Patagonian Mountain viscacha, Lagidium boxi (Mammalia: Rodentia)

The material consists of the ovaries from a pregnant female and observations on a live female of the Patagonian species of Mountain viscacha (Lagidium boxi). The study is reported because it shows that L. boxi, like the Peruvian Mountain viscacha (JL. peruanum), appears to ovulate only from the right ovary (Pearson, 1949). Features of the material are compared with information known for other hystricomorph rodents.     

Comparative study of the phylogenetic structure in six Apodemus species (Mammalia,Rodentia) inferred from ISSR-PCR data

The utility of the Inter Simple Sequence Repeat-Polymerase Chain Reaction (ISSR-PCR) was explored in order to determine genetic variation in six species of the genus Apodemus (A. flavicollis, A. sylvaticus, A. uralensis, A. agrarius, A. mystacinus and A. epimelas) at the individual level, population level, in separate geographic samples and in the species as a whole. Six optimized primers produced highly reproducible and polymorphic DNA markers with 98.3% polymorphic bands on a total sample of 91 individuals from 32 localities in Europe and Asia. Moreover, each primer allowed for an exact diagnosis of each of the six Apodemus species and thus provides a simple and reliable tool for the hitherto problematic discrimination of species from the subgenus Sylvaemus. Genetic distances between species ranged from 0.079, among the closely related A. flavicollis and A. sylvaticus, to 0.203 between A. mystacinus and A. agrarius. A. flavicollis, A. uralensis and A. sylvaticus display a strong population substructure. The range of genetic distances among geographic samples within last two species reaches the values obtained for closely related species. ISSR markers proved to be a simple and reliable tool for species diagnosis, as well as for estimating genetic diversity below the species level and for closely related species, but they showed questionable reliability for larger genetic distances.     

Evolution of a dental character in the beaver Castor fiber L. (Mammalia: Rodentia)

Variation in morphology of beaver cheek teeth has been examined in respect of ontogeny, geographical variation and geological time. When the effects of ontogeny are taken into account, certain patterns of dental variation are found to be restricted in space and time. An isolated loop of enamel ubiquitously present in the lower third molars of European beavers from the present interglacial seems to be a "new" acquisition which is lacking in Recent Siberian and North American beavers, as well as in Western European specimens from earlier interglacials.
Whilst the genetic basis of such morphological details is presumed rather than established, they may be helpful in tracing past population movements and are also of potential stratigraphic importance. Changes in range associated with Pleistocene climatic oscillations have led to the "sudden" appearance of this and other castorid dental characters in the Western European fossil record. The morphological discontinuity in the fossil record should be taken as evidence of climatic change rather than evidence for the operation of a certain pattern of evolution.