Susceptibility of Djungarian hamsters (Phodopus sungorus) to Neospora caninum infection

Djungarian hamsters were examined for the susceptibility to Neospora caninum infection. After 29 Djungarian hamsters were intraperitoneally inoculated with 5 x 10(6) N. caninum tachyzoites of JPA1 strain, some animals showed symptoms such as ataxia, and many tissue cysts were detected in the brain and a cyst in the muscular tunics of stomach. Especially, more than 100 cysts per head were observed after 5 weeks post inoculation. It is suggested that the Djungarian hamster is a model useful to examine neosporosis.     

Morphological characterization of skin ganglion-like cells in Djungarian hamsters (Phodopus sungorus)

Characteristic ganglion-like cell proliferation observed in the skin of Djungarian hamsters was investigated using 24 male and 24 female hamsters, 1-6 months of age, to examine the anatomic location of these ganglion-like cells and their morphologic features. One abdominal skin tumor composed of these cells and resembling proliferative fasciitis in humans was also examined. Skin ganglion-like cells were rarely observed in young animals but increased in number and extent with age, especially in males. These cells were frequently seen in the ventral and medial regions of the trunk and legs rather than in the dorsal and lateral regions. Light microscopic examination of these ganglion-like cells revealed abundant vesicular basophilic cytoplasm with delicate intracytoplasmic silver stain-positive fibrils. Ultrastructurally, these cells contained abundant rough endoplasmic reticulum and Golgi complexes with dilated cisternae; intracellular collagen fibrils were present within these cisternae. Heat shock protein 47, beta-tubulin, and androgen receptor were expressed in these cells. The morphologic features of cells of one tumor resembling human proliferative fasciitis were identical to those observed in ganglion-like cells. The results of the present study suggest that these ganglion-like cells are derived from intrinsic undifferentiated mesenchymal cells in the dermis or subcutaneous adipose tissue and that any tumor-like lesion they form should be regarded as an abnormal proliferative lesion of skin ganglion-like cells rather than as proliferative fasciitis or fibroma.     

Spontaneous buphthalmos in the Djungarian hamster (Phodopus sungorus campbelli)

Four Djungarian hamsters ( Phodopus sungorus campbelli ) were examined because of insidious globe enlargement, visual impairment and secondary altered behavior. Buphthalmos, deep anterior chambers, widely dilated pupils and poor to absent pupillary light reflexes were evident bilaterally in all four animals. Pale retinae and atrophic optic nerve heads were observed in the oldest hamsters. Light microscopic findings, including uveal atrophy, retinal atrophy (especially the inner retina), and a relative decrease in ganglion cells and optic nerve atrophy, were consistent with glaucoma. The etiology was unclear, but a genetic predisposition cannot be excluded.     

Susceptibility of Chinese hamsters (Cricetulus griseus) to the infection of Babesia microti

Chinese hamsters were examined for the susceptibility to the infection with Babesia microti based on the hematological parameters during the course of infection. A marked decrease in the RBC count, Ht value, Hb concentration, and an increase in WBC count due to the development of neutrophils or monocytes were recognized with the progress of parasitemia. Remarkable clinical findings were anemia and persistent infection with a low level of parasite burden in the chronic and convalescent stages. From these findings, it was concluded that Chinese hamsters were susceptible to infection with B. microti and would be useful for infection examination with the parasite.     

Spontaneous extraskeletal osteosarcomas of the subcutis in Djungarian hamsters (Phodopus sungorus): report of two cases

Spontaneous subcutaneous extraskeletal osteosarcoma was diagnosed in the subcutaneous tissue of two Djungarian hamsters. Histologically, the tumour was characterized by multiple nests of osseous and cartilaginous components within a proliferation of pleomorphic cells. No abnormality was observed in any skeletal bones and no change suggesting tumorous growth was observed in any other sites. This is the first report of extraskeletal osteosarcomas in Djungarian hamsters.     

The Structure of the Brachial Plexus of the Djungarian Hamster (Phodopus sungorus)

Veterinary Research Communications - Hamsters are often chosen as companion animals but are also a group of animals frequently subjected to laboratory tests. As there are no scientific publications...     

Disparities in activity levels and learning ability between Djungarian hamster (Phodopus sungorus) and Roborovskii hamster (Phodopus roborovskii)

The Djungarian hamster and the Roborovskii hamster belong to the same genus of Phodopus. However, the Djungarian hamster is tame and shows sedative behavior, while Roborovskii hamster is not tame and shows high levels of locomotor activity. Hyperactivity occurs in animals with tameless behavior. Tameness or tamelessness behavior is very important because tameness helps for breeding and controlling as well as it enables a strong human‐animal bond. In the present study, we examined the relationships between activity levels and cognitive function in Djungarian and Roborovskii hamsters. Three types of behavioral tests were performed to analyze their activity levels, memory and leaning ability. The levels of L‐ and D‐amino acids and monoamines in the brain were then determined. Roborovskii hamsters showed significantly higher locomotor activity than Djungarian hamsters. Memory ability was not significantly different between the two hamsters, but Roborovskii hamsters showed lower learning ability. Brain levels of D‐serine which is related to enhancement in memory and learning ability, were significantly higher in Djungarian hamsters, but the reverse was true for brain dopamine and serotonin levels. These results suggest that these differences in brain metabolism may be related to the behavioral differences between the two hamsters.     

Cryopreservation and In Vitro culture of Preimplantation Embryos in Djungarian Hamster (Phodopus sungorus)

Although embryo cryobanking was applied to Syrian golden and to Campbell's hamsters, no attempt has been made at freezing embryos in Djungarian hamsters. Four‐cell stage embryos were flushed from the reproductive ducts of pregnant females before noon of the third‐day post coitum and frozen in 0.25‐ml straws according to standard procedures of slow cooling. A mixture of permeating (ethylene glycol) and non‐permeating (sucrose) cryoprotectants was used. The thawing was performed by incubating at RT for 40 s followed by 40 s in a water bath at 30.0°C. Most (66.7%) of the non‐frozen four‐cell embryos developed up to the morula stage in rat one‐cell embryo culture medium (R1ECM). The use of hamster embryo culture medium (HECM) yielded fewer morulas (18.2%) during the same 24‐h period of culture. The rate of embryo's surviving the freezing–thawing procedures, as estimated by light microscopy, was 60.7–68.8%. After 24‐h culturing in R1ECM, 64.7% of frozen–thawed four‐cell embryos developed and all of them reached the morula stage. Supplementation of R1ECM with GM‐CSF (2 ng/ml) improved the rate of Djungarian hamster frozen–thawed embryo development: 100% of the four‐cell stage embryos developed, 50% of them achieved the morula stage, and 50% developed even further and reached the blastocyst stage within 24 h of culturing. This study reports the world's first successful transfer of frozen–thawed Djungarian hamster embryos yielding term pups. Taken together, the results of this study demonstrate the possibility of applying some key reproductive technologies, that is, embryo freezing/cryopreservation and in vitro culture, to Djungarian hamsters.     

Molecular clonings and sequences of Djungarian (Phodopus sungorus) and Chinese (Cricetulus griseus) hamster interferon-gammas

Djungarian (Phodopus sungorus) and Chinese (Cricetulus griseus) hamster IFN-gamma genes were cloned and sequenced. The Djungarian and Chinese hamster genes were both 525bp nucleotides, resulting in 174 amino acids in full length with a predicted molecular weight (MW) of 19,560 dal and 19,775 dal, respectively. The first 23 amino terminal amino acids consisted of a hydrophobic signal sequence when cleavaged, which would result in a mature 151 amino acid polypeptide with a predicted MW of 17,115 dal in the Djungarian hamster IFN-gamma and 17,255 dal in the Chinese hamster one.     

Molecular cloning and sequences of interleukin-10 in the Djungarian (Phodopus sungorus), Chinese (Cricetulus griseus), and Syrian (Mesocricetus auratus) hamster

Interleukin 10 (IL-10) genes of Djungarian, Chinese, and Syrian hamsters were cloned. The clones of IL-10 consisted of 537 bp nucleotides and 178 amino acids in full length, and the nucleotide and amino acid sequences exhibited a high degree of homology with those of the mouse and human. Since the number and position of signal sequences, N-glycosylations and cysteine sites in the IL-10 amino acid sequences of the hamsters were the same as those of the mouse, we suggest that the IL-10 molecular structures of the hamster are closer to that of the mouse than human.     

Suppression of Babesia microti infection in mice concurrently infected with Fasciola hepatica

Blood cell parasitaemia of Babesia microti and the associated haematological changes were examined in mice harbouring patent Fasciola hepatica infections and in fluke-free control mice. B. microti parasitaemia was markedly suppressed in mice harbouring primary 7-week F. hepatica infections, as reflected in a reduction in the percentage of erythrocytes parasitised and in the incidence of multiple B. microti infections in the red cells. This suppression was accompanied by an annulment of B. microti induced reductions in haemoglobin and haematocrit levels in F. hepatica infected mice. In naive recipient mice, inoculated with blood from mice concurrently infected with F. hepatica and B. microti, the course of B. microti infection was characterised by a prolonged pre-parasitaemia period, a reduced peak parasitaemia and a delayed fall in haematocrit levels as compared to those inoculated with blood from mice infected with B. microti only. This feature may presumably be dose-related. The present study does not reveal the actual mechanism(s) involved in the suppression of the blood protozoan by F. hepatica. However, since B. microti has a preference for mature erythrocytes, the suppression may be a result of the altered erythrocyte kinetic state induced by the removal of erythrocytes by the blood-sucking fluke resulting in high levels of reticulocytes.     

Suppression of Babesia microti infection in mice concurrently infected with Schistosoma mansoni

Blood cell panasitaemias of Babesai microti and associated haematological changes were studied in mice concurrently infected with Schistosoma mansoni and in controls with no schistosome infections. In comparison to the controls B. microti parasit-aemias were suppressed markedly in mice harbouring 6 and 8 weeks old patent S. mansoni infections at the time of infection with B. microti. The suppression was accompanied by an alleviation/annulment of the B. microti induced reductions in haemoglobin and haematocrit levels and in its erythropoetic stimulation. The suppressive effect of patent S. mansoni infections on B. microti is suggested to be at least partly attributable to non-specific immunological factors although the altered erythrocyte kinetic state induced by the schistosoma infection in combination with the preference of B. microti for mature (old) erythrocytes might also play a role in the suppression. In mice harbouring 2 weeks old prepatent S. mansoni infections B. microti was not suppressed.     

Influence of zinc deficiency to the mice infected with Babesia microti

Zinc (Zn) is an essential trace element for DNA synthesis and for cell growth and differentiation. The deficiency induces a wide range of disorders including immunodeficiency. In this study, the influence of Zn deficiency to the mice infected with Babesia microti was examined, and was compared with the influence in the rats infected with B. rodhaini previously reported. Experiments of B. microti infection were conducted using Zn-deficient (ZD; allowed to eat ad libitum on the ZD diet), Zn-adequate (ZA; allowed to eat ad libitum on the ZA diet), and diet-restricted (DR; supplied 2 g/day on the ZA diet) mice. It was suggested that the Zn deficiency exacerbated the infection dynamics of the mice with B. microti by the growth retardation, the reduction of immunity and the decrease in PCV. The results in the mice supported the consequences in the rats previously reported.     

Hematological findings and antibody responses in Syrian hamster (Mesocricetus auratus) infected with Babesia microti

Hematological findings during the course of infection and the antibody response in Syrian hamsters infected with Babesia microti were examined. A macrocytic hypochromic anemia with an increase of the reticulocyte count was detected as a rise in the parasitized erythrocyte rate. White blood cell counts also remarkedly increased with the increases of both neutrophils and active-shaped monocytes, and thus they particularly play an important role in eliminating the parasite. In Western blotting with the sera from the hamsters infected with B. microti, a 38 kDa protozoan antigen reacted to the early-term sera, and additionally 28, 32, and 34 kDa antigens also reacted to the medium- and latter-term, and convalescent sera. These antigens were immunodominant and the antibodies against these antigens had also important roles for inhibition of this parasite.     

Comparison of the effect of T-2 toxin with that of dexamethasone or cyclophosphamide on resistance to Babesia microti infection in mice

The effect of T-2 toxin on host resistance to acute and latent Babesia microti infections was evaluated in mice and was compared with the effects of the immunosuppressive drugs dexamethasone and cyclophosphamide. Mice with acute or latent B microti infection were treated with 2 mg of T-2 toxin/kg of body weight, 0.2 mg of dexamethasone/kg, or 30 mg of cyclophosphamide/kg daily for 5 days. Treatment with dexamethasone or cyclophosphamide caused significant (P less than 0.05) increases in Babesia parasitemia during acute infection and significantly (P less than 0.05) prolonged the duration of parasitemia during acute babesiosis. Treatment with T-2 toxin caused a transient significant (P less than 0.05) increase in Babesia parasitemia on day 10 after acute infection and numerical, though statistically nonsignificant, increases in the maximal level and duration of parasitemia during acute babesiosis. Significant (P less than 0.005) recrudescence of parasitemia was observed in the dexamethasone- and cyclophosphamide-treated mice with latent Babesia infection. Treatment with T-2 toxin did not cause recrudescence of parasitemia in mice with latent Babesia infection.     

Proteomic profiling of Rhipicephalus (Boophilus) microplus midgut responses to infection with Babesia bovis

Differences in protein expression in midgut tissue of uninfected and Babesia bovis-infected southern cattle ticks, Rhipicephalus (Boophilus) microplus, were investigated in an effort to establish a proteome database containing proteins involved in successful pathogen transmission. The electrophoretic separation of midgut membrane proteins was greatly improved by using liquid-phase isoelectric focusing combined with one-dimensional or two-dimensional (2-D) gel electrophoresis. A selection of differentially expressed proteins were subjected to analysis by capillary-HPLC-electrospray tandem mass spectrometry (HPLC-ESI-MS/MS). Among the identified Babesia-affected tick midgut proteins were six proteins that are implicated in signaling processes, including three Ca(2+)-binding proteins, a guanine nucleotide-binding protein, a protein with signal peptide activity and a translocon-associated receptor protein. Up-regulation of five metabolic enzymes indicated parasite-induced changes in electron and proton transport, protein processing and retinoic acid metabolism. Among the down-regulated proteins were a molecular chaperone, a cytoskeletal protein and a multifunctional protein of the prohibitin family. Identification of these proteins may provide new insights into the molecular interactions between B. bovis and its tick vector, and could lead to identification of anti-tick and transmission-blocking vaccine candidates.