Strongyloides stercoralis: oral transfer of parasitic adult worms produces infection in mice and infection with subsequent autoinfection in gerbils.

Oral transfer of parasitic adult Strongyloides stercoralis produced patent infections in gerbils, C57BL/6J and SCID mice. In gerbils receiving adult worms, 7.3% of the transferred worms established and autoinfective L3 were found beginning on day 5 post-transfer, with peak numbers seen on days 6 and 7 post-transfer and few seen by 9 days post-transfer. These results suggest that development of autoinfective L3 in the gerbil is limited by the immune response of the host. When given orally to mice, between 7.2% (C57BL/6J) and 19.5% (SCID) of the adult worms established. These levels are higher than those previously obtained by the subcutaneous infection of SCID mice with infective larvae. No autoinfective larvae were found in infected mice and the ratio of L1/adult worms was small compared with that seen in gerbils. Thus, mice infected orally can be used as a model to study the interaction between the adult worm and the host, and since autoinfection has not been seen in the murine model, as developed to date, orally infected mice may be useful as a model to study mechanisms preventing autoinfection.     

Experimental inoculation of meadow voles (Microtus pennsylvanicus), house mice (Mus musculus), and Norway rats (Rattus norvegicus) with Mycobacterium bovis

Mycobacterium bovis has a wide host range that includes several wildlife species, and this can hamper attempts to eradicate bovine tuberculosis from livestock. The purpose of this study was to determine if common rodent species, namely meadow voles (Microtus pennsylvanicus), house mice (Mus musculus), and Norway rats (Rattus norvegicus), that inhabit the bovine tuberculosis endemic area of Michigan, can be experimentally infected with M. bovis. The objectives of the study were: 1) to determine if these rodent species can be infected, and if so, to document attendant pathologic processes/pathogenesis; 2) to detect any fecal shedding of M. bovis; and 3) to evaluate the relative susceptibility of the three species to M. bovis infection. For each species (n=36) there were two treatment (n=12/group) and one or two control groups depending on species (n=6-12/group); the maximum study duration was 60 days. The meadow vole treatments consisted of high dose inocula that were given by oral or intranasal routes, whereas the house mice and Norway rats were given only oral inocula at either a high or low dose. Of the three species, meadow voles were most susceptible to M. bovis infection. Upon intranasal inoculation, all 12 voles were infected as determined by gross and microscopic lesions and culture of M. bovis from tissue and feces. Seven of the 12 meadow voles inoculated orally were infected. House mice also were susceptible; M. bovis was isolated from 14 of 24 animals. Only one Norway rat in the high dose treatment group was positive by culture and this was the only animal from which minimal attendant lesions were observed. Results of this study indicate that meadow voles and house mice can be infected with M. bovis and might serve as spillover hosts. Concerted efforts should, therefore, be made to reduce or eliminate these rodents on premises where M. bovis-infected livestock are present.     

Leishmania tropica infection in hamsters and a review of the animal pathogenicity of this species.

Four strains of Leishmania tropica s. st. from Afghanistan were found to be constantly infective to the golden hamster (Mesocricetus auratus), whether inoculated as culture promastigotes from early passages or as amastigotes from the cutaneous lesions. In total, 66 amastigote passages were carried out over 6 passage generations. The footpad lesions were chronic and nonulcerative infiltrates; their evolution is described up to 15 months. No self-healing was observed. Balb/c mice and gerbils were not susceptible. Earlier studies on L. tropica s. st. in laboratory animals, principally by Soviet and French workers, are critically reviewed. This new experimental model of chronic cutaneous leishmaniasis is of special interest for studies on the immunology and chemotherapy of the disease. Some advantages over the commonly used L. major model are discussed.     

长爪沙鼠血清雌性激素的比较研究

目的测定长爪沙鼠、NIH小鼠和SD大鼠的血清雌二醇(E2)和孕酮(P)水平,为研究长爪沙鼠的生殖和胚胎工程提供基础资料。方法用放射免疫分析法测定上述动物生产前后血清雌二醇(E2)和孕酮(P)水平,进行统计学处理和分析。结果不同阶段雌性沙鼠E2值差异无显著性(P>0.05),P值差异有显著性(P<0.01);E2值比较,处女期沙鼠与同期NIH和SD差异有显著性(P<0.01),而在经产期的动物间水平接近(P>0.05);P值比较,处女期沙鼠与NIH接近,与SD差异有显著性(P<0.01);而经产期沙鼠在三种动物中是最高的(P<0.01)。结论长爪沙鼠血清E2、P的含量具种属特异性,并随动物的生理发育时期而变化。     

The ultrastructure of the interaction of Rickettsia sibirica and R. slovaca with the cells of ixodid ticks

The ultrastructural aspects of the interaction of R. sibirica and R. slovaca with cells of mites of the species Dermacentor reticulatus, D. marginatus and Ixodes ricinus after their parenteral infection, as well as in the organs of D. marginatus infected naturally in the environment, have been studied. Both rickettsial species have similar morphology in different organs of the vector. These rickettsiae not only multiply, their populations are also partly destroyed in phagolysosomes. The natural mixed infection of R. sibirica and orbivirus in cells of D. reticulatus is described. As shown in this study, both associates pass through the complete ontogenetic cycle of development on the level of the host body and also on the level of an individual cell.     

Changes in the antimicrobial potential of the phagocytosing cells of great gerbils in experimental plague

The work deals with the results obtained in the study of the activity of the cytocidal systems of phagocytes in great gerbils under normal conditions and during the plague infectious process. The data have been analyzed in comparison with the corresponding characteristics of phagocytic activity in mice. Changes in the oxygen-dependent metabolism (ODM) of neutrophils and macrophages, responsible for the functioning of their oxygen-dependent cytocidal systems, in plague show features characteristic of the nonspecific systemic postaggression reaction (SPAR). In Y. pestis-sensitive animals (mice), changes in the ODM activity of phagocytes are manifested as shock of different severity. In great gerbils, these changes present as true SPAR. The degree of the sensitivity of animals to Y. pestis infection is mainly determined by the initial level of the activity of oxygen-sensitive cytocidal systems of neutrophils (determined in the nitro blue tetrazolium spontaneous reduction test). In great gerbils this level exceeds the corresponding characteristics in mice 2.6- to 8.7-fold.     

Syphacia obvelata in the Mongolian gerbil (Meriones unguiculatus): natural occurrence and experimental transmission

An adult from a research colony and a litter of 5-week-old Mongolian gerbils (Meriones unguiculatus) from a pet store were found to have pinworms identified as Syphacia obvelata. The infected gerbils were allowed to cohabitate with uninfected gerbils. Similarly, infected gerbils were caged with uninfected mice and infected mice with uninfected gerbils. Results of these studies showed that Syphacia obvelata can be transmitted from gerbil to gerbil, gerbil to mouse, and mouse to gerbil.     

Susceptibility of four species of small rodents to encephalomyocarditis (EMC) virus infection

The D variant of encephalomyocarditis virus (10(1)-10(5) PFU/head) was intraperitoneally inoculated into 4 species of small rodents, rats, mice, Syrian hamsters, and Mongolian gerbils, and the susceptibility of these animals to EMC virus was examined virologically and histopathologically 3 days after infection. Viral replication was detected in the brain (mice), in the heart (mice and gerbils), and in the pancreas (mice, hamsters, and gerbils). No viral replication was detected in rats. Histopathological changes were seen in the brain (mice and hamsters), in the heart (mice and gerbils), and in the pancreas (mice, hamsters, and gerbils). No histopathological changes were seen in rats. The present results suggest that it may be quite possible to produce EMC virus-induced diabetes mellitus not only in mice but also in hamsters and gerbils.     

Great adaptability of brown adipose tissue mitochondria to extreme ambient temperatures in control and cold-acclimated gerbils as compared with mice

1. The gerbil (Gerbillus campestris) is a desert rodent able to tolerate high (38 degrees C) and low (-20 degrees C) ambient temperatures, probably due to both its low resting metabolic rate in hot environment and its high peak metabolic rate in cold. 2. Measurement of mitochondrial state IV respiration and cytochrome-oxidase activity (COX) were made in interscapular brown adipose tissue (IBAT), liver and hind limb muscles of gerbils and mice of nearly equal body mass, acclimated for 4 weeks at cold ambient temperature (CA) or reared at thermoneutrality (TN). 3. The most striking difference between these two animal species appears to be in IBAT mitochondria: in TN animals, the level of state IV respiration and COX activity was lower in gerbils than in mice, but the cold acclimation-induced increase in these parameters was greater in gerbils than in mice. 4. Alternatively, in gerbils as in mice, cold acclimation induced a reduction in muscle mitochondrial COX activity. No important change due to cold acclimation was observed in liver mitochondria, either in gerbils or in mice. 5. As compared with mice, the lower state IV respiration in IBAT mitochondria from TN gerbils may explain their low RMR, whereas the higher COX activity of IBAT mitochondria from CA gerbils may explain their higher PMR. 6. As a result of this great adaptability of BAT mitochondria, the gerbil seemed to be able to live in a wide range of ambient temperatures in its natural habitat.     

幽门螺杆菌动物模型研究进展

幽门螺杆菌动物模型用于HP相关疾病和HP疫苗作用的研究。常规实验动物包括悉生猪、悉生狗、非人类灵长动物、猫、雪貂、小鼠、大鼠、沙鼠等。猫螺杆菌和雪貂螺杆菌感染也被用于模型研究。最近,转基因小鼠和基因敲除小鼠也被用作幽门螺杆菌动物模型研究。     

Variability of diurnality in laboratory rodents

The locomotor activity rhythms of domestic mice, laboratory rats, Syrian hamsters, Siberian hamsters, Mongolian gerbils, degus, and Nile grass rats were compared. Running-wheel activity was monitored under a light–dark cycle with 12 h of light and 12 h of darkness per day. Nile grass rats were found to be reliably diurnal, whereas laboratory rats, Siberian hamsters, domestic mice, and Syrian hamsters were reliably nocturnal. Both diurnal and nocturnal subgroups were observed in Mongolian gerbils and degus. A downward gradient of diurnality was observed from Mongolian gerbils classified as diurnal, degus classified as diurnal, gerbils classified as nocturnal, and degus classified as nocturnal. Nocturnal degus remained nocturnal when tested with an infrared motion detector without running wheels. Thus, although the diurnal–nocturnal dichotomy could be applied to some of the species, it was not appropriate for others. The dichotomy may reflect researchers’ needs for systematization more than a natural distinction between species. Through mechanisms as yet poorly understood, the balance between entraining and masking processes seems to generate a gradient of temporal niches that runs from predominantly diurnal species to predominantly nocturnal species with many chronotypes in between, including species that exhibit wide intra-species gradients of temporal niche.     

Loss of infectivity of Neospora caninum oocysts maintained for a prolonged time

The purpose of this study was to investigate whether sporulated Neospora caninum oocysts, which had been stored for 46 mo in a 2% sulfuric acid solution at 4 degrees C, remain morphologically viable and infective to gerbils (Meriones unguiculatus). Six gerbils were orally inoculated with doses of 400 or 1,200 oocysts. Two mo after inoculation, the animals did not show any clinical signs, had no histological lesions, and were seronegative for N. caninum at 1: 50 in an immunofluorescent antibody test. PCR using the brain from each gerbil did not reveal N. caninum specific DNA. We conclude that oocysts preserved for 46 mo are not infective, despite being morphologically intact.     

Reservoirs of Giardia spp. in southwestern Alberta

A survey of potential hosts of Giardia spp. was carried out during 1982 and 1983 in the Kananaskis Valley and Banff National Park, Alberta, Canada. Diagnosis was based mainly on fecal analysis but a few animals were examined at necropsy and scrapings from the small intestine analyzed. A total of 304 specimens was examined from humans (Homo sapiens L.) and a variety of animal species. Cysts and/or trophozoites of Giardia were found in 10.5% of the specimens examined. Positive samples were found from 20 of 21 red-backed voles (Clethrionomys gapperi Vigors), two of six meadow voles (Microtus pennsylvanicus Ord), one of three long-tailed voles (Microtus longicaudus Allen), five of 50 deer mice (Peromyscus maniculatus Mearns), and two of 58 beavers (Castor canadensis Kuhl). Cysts obtained from a beaver were successfully introduced to gerbils (Meriones unguiculatus Milne-Edwards) and the trophozoites obtained were cultured in vitro.     

Prion protein amino acid determinants of differential susceptibility and molecular feature of prion strains in mice and voles

The bank vole is a rodent susceptible to different prion strains from humans and various animal species. We analyzed the transmission features of different prions in a panel of seven rodent species which showed various degrees of phylogenetic affinity and specific prion protein (PrP) sequence divergences in order to investigate the basis of vole susceptibility in comparison to other rodent models. At first, we found a differential susceptibility of bank and field voles compared to C57Bl/6 and wood mice. Voles showed high susceptibility to sheep scrapie but were resistant to bovine spongiform encephalopathy, whereas C57Bl/6 and wood mice displayed opposite features. Infection with mouse-adapted scrapie 139A was faster in voles than in C57Bl/6 and wood mice. Moreover, a glycoprofile change was observed in voles, which was reverted upon back passage to mice. All strains replicated much faster in voles than in mice after adapting to the new species. PrP sequence comparison indicated a correlation between the transmission patterns and amino acids at positions 154 and 169 (Y and S in mice, N and N in voles). This correlation was confirmed when inoculating three additional rodent species: gerbils, spiny mice and oldfield mice with sheep scrapie and 139A. These rodents were chosen because oldfield mice do have the 154N and 169N substitutions, whereas gerbil and spiny mice do not have them. Our results suggest that PrP residues 154 and 169 drive the susceptibility, molecular phenotype and replication rate of prion strains in rodents. This might have implications for the assessment of host range and molecular traceability of prion strains, as well as for the development of improved animal models for prion diseases.     

Rederivation of Helicobacter hepaticus-infected Mongolian gerbils by Caesarean section and cross-fostering to rats and mice

The Mongolian gerbil serves as an animal model for a wide range of diseases. As these animals are extensively used for the study of Helicobacter pylori-induced gastritis, naturally occurring infections with rodent Helicobacter species in gerbils are a possible source of interference in studies of H. pylori-associated disease. The gerbil stock at the Central Animal Facility in Hannover was persistently infected with H. hepaticus. The aim of this study was to derive Helicobacter species-free Mongolian gerbils. Therefore, germfree gerbil pups were obtained by Caesarean section and the pups were transferred to female rats and mice with recently delivered litters. In total, four Ztm:NMRI mice, four Ztm:SPRD rats and one DA/Ztm rat that originated from a specified pathogen-free area were selected to serve as foster mothers. With this approach, it was possible to obtain Helicobacter-free gerbils. Rearing by mice was more successful than by rats, as six of nine gerbils were reared by mice, but only one of 29 gerbils was reared by rats.     

Metabolic adaptations of the gerbil, Gerbillus campestris, to a desert climate. Comparison with white mice

Metabolic rate of gerbils was lower than that of mice (35%). We tried to assess the part played by brown adipose tissue in this low level. Mitochondrial respiration (state 4), protein content and cytochrome-oxidase activity of interscapular BAT mitochondria were very low in gerbils compared to mice, whereas in liver and muscle these parameters were not significantly different. Like in fasting animals, the low level of basal energy expenditure of gerbils may be ascribed to low activity of BAT.     

Hyperinfective strongyloidiasis: Strongyloides stercoralis undergoes an autoinfective burst in neonatal gerbils

One of the unusual aspect of the life cycle of Strongyloides stercoralis is the occurrence of autoinfective third-stage larvae (L3a). These are the causative agents of severe hyperinfective strongyloidiasis. When 6-wk-old gerbils are infected with 1,000 infective third-stage larvae (L3i), no L3a are seen during the course of the infection. However, in neonatal gerbils (1-13 days of age) infected with 1,000 L3i, a burst of autoinfection takes place between 15 and 30 days postinfection (PI). Only occasional L3a can be found in neonatally infected gerbils after 4 wk PI. This autoinfective burst is not seen in neonatal gerbils infected with 200 L3i.     

Malate dehydrogenase and lactate dehydrogenase in trematodes and turbellarians

Studies have been made on the activity and properties of malate and lactate dehydrogenases from the cattle rumen trematodes Eurytrema pancreaticum, Calicophoron ijimai and the turbellarian Phagocata sibirica which has a common free-living ancestor with the trematodes. All the species studied have a highly active malate dehydrogenase, its activity in the reaction of reducing oxaloacetate being 6-14 times higher than in the reaction of malate oxidation. The affinity of malate dehydrogenase to oxaloacetate was found to be higher than that to malate. The activity of lactate dehydrogenase (reducing the pyruvate) was lower than the activity of malate dehydrogenase, the difference being 50 times for C. ijimai, 4 times for E. pancreaticum and 10 times for P. sibirica.     

Immunocytochemical studies on parafollicular cells of various mammals

Using specific antisera, calcitonin, calcitonin gene-related peptide (CGRP), somatostatin as well as neuron-specific enolase, chromogranin, secretory peptide I and calbindin (vitamin D-dependent calcium-binding protein) were looked for in parafollicular cells of rats, Syrian hamsters, Mongolian gerbils, mice, guinea pigs, rabbits and pigs. Calcitonin and CGRP were most invariably present in various species. Somatostatin was absent in mice and Mongolian gerbils and present in variable amounts in the remaining species. Neuron-specific enolase could not be detected in rabbits, while in the pigs and the Mongolian gerbils it could be demonstrated only in some parafollicular cells. Calbindin was present exclusively in parafollicular cells of guinea pigs. Chromogranin and secretory protein-I were present only in some animal species.     

Species and individual differences in juvenile female alloparental care are associated with oxytocin receptor density in the striatum and the lateral septum

The neuropeptide oxytocin has been implicated in the regulation of affiliative behavior and maternal responsiveness in several mammalian species. Rodent species vary considerably in the expression of juvenile alloparental behavior. For example, alloparental behavior is spontaneous in juvenile female prairie voles (approximately 20 days of age), takes 1-3 days of pup exposure to develop in juvenile rats, and is nearly absent in juvenile mice and meadow voles. Here, we tested the hypothesis that species differences in pup responsiveness in juvenile rodents are associated with oxytocin receptor (OTR) density in specific brain regions. We found that OTR density in the nucleus accumbens (NA) is highest in juvenile prairie voles, intermediate in juvenile rats, and lowest in juvenile mice and meadow voles. In the caudate putamen (CP), OTR binding was highest in prairie voles, intermediate in rats and meadow voles, and lowest in mice. In contrast, the lateral septum (LS) shows an opposite pattern, with OTR binding being high in mice and meadow voles and low in prairie voles and rats. Thus, alloparental responsiveness in juvenile rodents is positively correlated with OTR density in the NA and CP and negatively correlated with OTR density in the LS. We then investigated whether a similar receptor-behavior relationship exists among juvenile female prairie voles by correlating individual variation in alloparental behavior with variation in OTR density. The time spent adopting crouching postures, the most distinctive component of alloparental behavior in juveniles, was positively correlated with OTR density in the NA (r = 0.47) and CP (r = 0.45) and negatively correlated with OTR density in the lateral septum (r = -0.53). Thus, variation in OTR density in the NA, CP, and LS may underlie both species and individual differences in alloparental care in rodents.