High sensitivity of fibroblast cell lines derived from LEC rats to heat treatment

A fibroblast cell line derived from LEC rat was approximately twofold more sensitive to heat treatment at 45 degrees C than were that from WKAH rat in terms of heating time required to attain 50% loss of survival in a colony forming assay. The present study was carried out for understanding the mechanism underlying the higher sensitivity of LEC rat cells to heat treatment. Although apoptosis was not found in WKAH rat cells, the percentages of apoptotic cells in LEC rat cells significantly increased after heat treatment. LEC rat cells showed significantly lower sensitivity in induction of cell death and apoptosis to ceramide, a lipid signaling molecule that is associated with heat-induced apoptosis, than did WKAH rat cells. SP600125, an inhibitor of JNK suppressed the induction of cell death in both heated LEC and WKAH rat cells, but SB203580, an inhibitor of p38 mapk, did not. The relative surviving fractions of heated LEC and WKAH rat cells in the presence of both SB203580 and SP600125 were higher than those of cells in the presence of SP600125 alone. The amounts of hsp70 protein in WKAH rat cells increased from 4 to 12 hr after heat treatment, but did not in LEC rat cells. These results suggest that higher thermosensitivity in the fibroblast cell line from LEC rat is due to low inducibility of hsp70 protein after heat treatment.     

Higher sensitivity in induction of apoptosis in fibroblast cell lines derived from LEC strain rats to ultraviolet B radiation

When lung fibroblast cell lines from LEC and WKAH rats were irradiated with ultraviolet B (UVB) and assayed for colony formation, LEC rat cells showed a higher sensitivity than did WKAH rat cells. The LEC rat cells were approximately 1.5-fold more sensitive to UVB radiation than were the WKAH rat cells in terms of D37 values, which are the doses of UVB required to reduce cell survival to 37%. When the rat cells were irradiated with UVB in the presence of 0.5 M dimethyl sulfoxide (DMSO), which efficiently scavenges free radicals such as hydroxyl radicals, no significant difference was observed between the survival curves of either LEC or WKAH rat cells irradiated with UVB in the presence of 0.5 M DMSO and those irradiated with UVB in the absence of DMSO. Therefore, formation of free radicals may not be involved in cell death induced by UVB radiation. Flow cytometry showed that the percentage of apoptotic cells in the LEC rat cell population increased with post-incubation time after UVB radiation. The proportion of apoptotic cells in the UVB-irradiated LEC rat cell population increased as the dose of UVB was increased. In contrast, no significant proportion of apoptotic cells was observed in the UVB-irradiated WKAH rat cell population. These results showed a higher sensitivity in induction of apoptosis by UVB radiation in LEC rat cells than in WKAH rat cells.     

Analysis of the cell cycle of fibroblasts derived from the LEC rat after X-irradiation

The LEC rat is reported to exhibit hypersensitivity to X-irradiation, deficiency in DNA double-strand break repair, and radio-resistant DNA synthesis. This character of the LEC rat has been thought to be due to abnormal G1 arrest in cells after X-irradiation. In this report, we re-investigated the effect of X-irradiation on the cell cycle in primary-cultured fibroblasts. Primary-cultured fibroblasts derived from LEC and BN rats were exposed to 4 Gy of X-ray and their cell cycle analysis was performed with a flow cytometer. Fibroblasts derived from both rats showed normal response of the cell cycle, indicating the arrest at both G1--and G2/M-phase and no difference in the cell cycle population between fibroblasts derived from both rats. In contrast, when the same analysis was performed using the cell line, L7 and W8, which had been established from the lung fibroblasts of LEC and control WKAH rats, respectively, by immortalizing with SV40 T-antigen, L7 cells but not W8 cells showed impaired G1 arrest and abnormal cell cycle. These results suggest that fibroblasts derived from LEC rats possess the normal cell cycle response after X-irradiation, if they are kept naive as not immortalized with SV40 T-antigen.     

Establishment and characterization of a fibroblast cell line derived from Mongolian sheep

The Mongolian sheep ear marginal tissue fibroblast cell line (MSF32) from 32 samples was successfully established by using primary explants technique and cell cryoconservation technology. MSF32 cells were adherent, with a population doubling time of 28.2 h. Chromosome analysis showed that >90.2% of cells were diploid (2n = 54) prior to cell passage 4. Isoenzyme analyses of lactate dehydrogenase and malate dehydrogenase showed that the MSF22 cells had no cross‐contamination with other species. Tests for cell line contamination with bacteria, fungi, viruses and mycoplasmas were also negative. Plasmids encoding the fluorescent proteins pEGFP‐N3, pEGFP‐C1, pECFP‐N1, pECFP‐mito, pDsRed1‐N1 and pEYFP‐N1 were transfected into cells to study exogenous gene expression in the cells. The plasmid transfection efficiency was between 12.3% and 63.3%. Every index of the MSF32 cell line meets all the standard quality controls of American Type Culture Collection (ATCC). Not only has the genetic resources of the Mongolian sheep been preserved at the cell level, but also valuable materials had been provided for genome, postgenome and somacloning research.     

Characterization of spheres derived from canine mammary gland adenocarcinoma cell lines

There is increasing evidence for the presence of cancer stem cells in several solid tumors, and these cancer stem cells have a potential role in tumor initiation, aggression, and recurrence. The stem cell-like properties of spheres derived from canine mammary tumors remain largely elusive. We attempted to induce sphere formation using four cell lines of canine mammary adenocarcinoma, and characterized the spheres derived from a CHMp line in vitro and in vivo. The CHMp-derived spheres showed predominantly CD44⁺CD24⁻ population, higher expression of stem cell-related genes, such as CD133, Notch3 and MDR, and higher resistance to doxorubicin compared with the CHMp-derived adherent cells. Xenograft transplantations in nude mice demonstrated that only 1 × 10⁴ sphere cells were sufficient for tumor formation. Use of the sphere assay on these sphere-derived tumors showed that sphere-forming cells were present in the tumors, and were maintained in serial transplantation. We propose that spheres derived from canine mammary adenocarcinoma cell lines possess a potential characteristic of cancer stem cells. Spheres derived from canine mammary tumors could be a powerful tool with which to investigate novel therapeutic drugs and to elucidate the molecular and cellular mechanisms that underlie tumorigenesis.     

Variation of virus replication in primary bovine kidney cell cultures derived from 68 three-day-old calves

Primary kidney cell cultures were prepared from 68 three-day-old calves. Complete monolayers of these cultures were infected separately with viral diarrhea, infectious bovine rhinotracheitis, parainfluenza, and adenovirus 7 viruses. The yield of virus from all infected cultures was calculated by plaque titer assay after 2 to 4 days' incubation. The variation of virus yield was substantial between individual cultures.     

Pluripotency network in porcine embryos and derived cell lines

Huge amounts of work have been dedicated to the establishment of embryonic stem cell lines from farm animal species since the successful isolation of embryonic stem cells from the mouse and from the human. However, no conclusive results have been obtained so far, and validated lines have yet to be established in domestic animals. Many limiting factors have been suggested and need to be studied further to isolate truly pluripotent cell lines from livestock. In this review, we will discuss the difficulties in deriving and maintaining embryonic stem cell lines from farm animal embryos and how can this lack of success be explained. We will summarize results obtained in our laboratory regarding derivation of pluripotent cells in the pigs. Problems related to the identification of standard methods for derivation, maintenance and characterization of cell lines will also be examined. We will focus our attention on the need for appropriate stemness-related marker molecules that can be used to reliably investigate pluripotency in domestic species. Finally, we will review data presently available on functional key pluripotency-maintaining pathways in farm animals.     

Analysis of marker expression in porcine cell lines derived from blastocysts produced in vitro and in vivo

The present study was designed to extensively characterize cell lines derived from porcine blastocysts by several methodical approaches, including morphological observation, cytogenetic analysis, estimation of alkaline phosphatase activity and detection of specific marker expression at the mRNA/protein level. A comparison was made between the properties of cell lines isolated from in vivo- and in vitro-obtained blastocysts. Our results showed that 57.1% of the in vivo-obtained blastocysts attached to the feeder layer and that 33.3% of them started to grow in a monolayer. The percentage of attached in vitro-produced blastocysts was lower (24.6%), and only 6.9% of them started to grow. Outgrowths from the in vitro-produced blastocysts formed mainly trophectoderm or epithelial-like monolayer, whereas the in vivo-obtained blastocysts formed heterogeneous outgrowths that also contained cells with embryonic stem (ES)-like morphology. Detailed analyses showed that the primary outgrowths with ES-like morphology expressed the pluripotency markers OCT-4 and NANOG and revealed intensive alkaline phosphatase staining, while they did not express markers of differentiation. The majority of passaged cells, including those with ES-like morphology, lacked OCT-4 protein and revealed expression of specific differentiation markers (cytokeratin 18, lamins A/C, transferrin, α-fetoprotein and GATA-4), although they still expressed NANOG and exhibited weak alkaline phosphatase activity. Moreover, these cells spontaneously differentiated into neural, fibroblast or epithelial-like cells, even in the presence of leukaemia inhibitory factor. Our results show that complex analysis of markers of pluripotency as well as differentiation markers is necessary for proper interpretation of data in porcine embryonic stem cell studies.     

Higher sensitivity of LEC strain rat in radiation-induced acute intestinal death.

LEC strain rats (LEC rats), which have been known to develop hereditarily spontaneous fulminant hepatitis 4-5 months after birth, were highly sensitive to whole-body X-irradiation as compared to WKAH strain rats (WKAH rats). Radiation-induced acute intestinal death occurred at doses higher than 6.5 Gy in LEC rats, and at doses higher than 12.8 Gy in WKAH rats, respectively. By the probit analysis of survival data, it was shown that the LD50/7 value of LEC rats was estimated to be 7.03 Gy which was significantly lower than that (12.99 Gy) of WKAH rats. Histopathological examinations of small intestines from LEC rats 2 days after irradiation at the dose of 8.5 Gy showed severe epithelial death together with edema, whereas little or no significant changes were noted in intestinal epithelium of 8.5 Gy-irradiated WKAH rats. These results suggest that the radiosensitivity of LEC rats to ionizing radiation appears to be higher than that of other strains of rats.     

Analysis of radiosensitivity of cancer stem‐like cells derived from canine cancer cell lines

Cancer stem‐like cells (CSCs) are self‐renewing cells comprising a small subpopulation in tumours, and generate differentiated progeny through asymmetric division. It has been shown that CSCs are resistant to ionizing radiation, and this feature could be one of the mechanisms of tumour recurrence after radiation therapy. Much attention has been focused on to target CSCs; however, difficult of isolating CSCs and lack of knowledge on their radiosensitivity have limited this kind of research in veterinary medicine. In the present study, sphere‐forming cells (SC), cultured using sphere formation method, were isolated from four type of canine tumour cell lines and evaluated if they have CSCs‐like properties by expression of CSCs markers (real‐time polymerase chain reaction) and capacity of tumorigenesis (xenograft transplantation in nude mice), and were assessed radiosensitivity (clonogenic survival assay) and DNA repair kinetics (immunofluorescence staining for p53‐binding protein 1) after X‐ray irradiation in comparison with the corresponding normal adherent culture cells (AC). All SCs were isolated using sphere formation and showed high gene expression of CD133 and tumorigenic ability as compared with AC. All SCs were significantly resistant against X‐ray irradiation as compared with AC. In addition, the amount of DNA double‐strand breaks after X‐ray irradiation were significantly lower in SC compared with the corresponding AC. These results indicate that SC isolated through sphere formation possess CSCs‐like characteristics and CSCs are important factor that affect radiosensitivity in canine tumours. In addition, radioresistance of CSCs may depend on reaction of DNA double‐strand break after X‐ray exposure.     

Quantitative analysis of pro-inflammatory cytokine mRNA expression in Theileria annulata-infected cell lines derived from resistant and susceptible cattle

The pathogenic mechanisms involved in tropical theileriosis, caused by the tick-borne protozoan parasite Theileria annulata, are unclear. Pathology is associated with the schizont stage of the parasite, which resides within bovine macrophages. Breed-specific differences in pathology have been observed in cattle, several Bos indicus breeds are relatively resistant to tropical theileriosis whilst Bos taurus cattle are highly susceptible. Infected cells express pro-inflammatory cytokines and it has been hypothesized that these cytokines play a major role in the pathology of the disease. Therefore, using quantitative RT-PCR we investigated the expression of the key candidates, interleukin 1 beta (IL-1beta), IL-6 and tumour necrosis factor alpha (TNF-alpha), in T. annulata low passage infected cell lines derived ex vivo from experimental infection of resistant and susceptible cattle. mRNA for each cytokine was detected in all cell lines investigated at levels higher than those observed in resting monocytes. However, the analyses did not identify any breed-specific differences. Therefore, these results are not consistent with the hypothesis that differential regulation of infected cell derived pro-inflammatory cytokines (IL-1beta, IL-6 and TNF-alpha) accounts for the breed-related differences in resistance and susceptibility to T. annulata infection. Other, currently unknown mechanisms may be of greater importance.     

Establishment and characterization of a thymidine kinase deficient avian fibroblast cell line derived from a Japanese quail cell line, QT35.

An avian thymidine kinase deficient (TK-) fibroblast cell line (QTTK-) was established from a Japanese quail cell line, QT35, and characterized the biological properties. QTTK- could grow in the presence of 5-bromo-2'-deoxyuridine (BUdR, 100 micrograms/ml) and not in the growth medium with hypoxanthine-aminopterin-thymidine. Compared to QT35 cells, the 3H-thymidine incorporation of the QTTK- cells and the TK activity of the cell extract significantly decreased to 0.3% and 0.5%, respectively. In the thymidylate synthetase activity, the karyotype, and the sensitivities to either fowlpox virus (FPV) or herpesvirus of turkeys (HVT), OTTK- cells were similar to the parental QT35 cells. Since QTTK- cells were permissive to FPV and HVT infections and these viruses could not grow in the presence of 50 to 75 micrograms/ml of BUdR, QTTK- cells may be useful for the construction of recombinant FPV and HVT that have foreign genes within the TK gene of the virus genome.     

Radiofrequency radiation at 40 kHz induces hepatic injury in Long-Evans Cinnamon (LEC) rats, an animal model for human Wilson disease

In the present study, we examined effects of radiofrequency (RF) radiation at 40 kHz on hepatic injury in Long-Evans Cinnamon (LEC) rats, an animal model for human Wilson disease, which is a heritable disease of copper metabolism in the liver. The activities of ALT and AST in serum of LEC rats exposed to RF radiation for 2 weeks were approximately 3.8-fold and 2-fold higher than those in serum of sham-exposed rats, respectively. Although there were no significant differences in hepatic copper contents between LEC rats exposed to RF radiation for 2 weeks and sham-exposed rats, copper contents in the kidney and serum of exposed LEC rats were approximately 4.2-fold and 12.9-fold higher than those in sham-exposed rats, respectively. Relative O??-scavenging activities in the S-100 fraction of the liver of LEC rats exposed to RF radiation for 2 weeks were 1.6-fold higher than those in sham-exposed rats. No significant differences were observed in activities of AST and ALT in serum and relative O??-scavenging activity in the S-100 fraction of the liver of normal control WKAH rats that were sham-exposed and exposed to RF radiation. No significant differences were observed in copper contents in the liver, kidney and serum of WKAH rats that were sham-exposed and exposed to RF radiation for 2 weeks. The results show that RF radiation at 40 kHz induced hepatic injury in LEC rats.     

Establishment of four pairs of canine mammary tumour cell lines derived from primary and metastatic origin and their E-cadherin expression

Four new pairs of canine mammary carcinoma cell lines derived from both primary and metastatic lesions were established. The cells were cultured in RPMI‐1640 with 10% fetal bovine serum and they showed stable growth for more than 120 passages. Using these cell lines, the expression of E‐cadherin was measured by flow cytometry and the function of E‐cadherin was evaluated by cell aggregation assay and results from the primary and metastatic lesions were compared statistically. E‐cadherin was strongly expressed in all of the cell lines, without a notable difference between cells of primary and metastatic origin. In the cell aggregation assay, the function of E‐cadherin was significantly weaker in the cells of primary origin (p < 0.05), as compared with cells of metastatic origin. The present results suggest that a reduction in E‐cadherin function may be implicated in the invasive and metastatic potential of canine mammary tumour cells; however, further study will be needed to clarify E‐cadherin function in the context of the metastasis of canine mammary carcinoma.     

Phenotypic analysis of lymphoblastoid cell lines derived from cattle and deer affected with "sheep-associated" malignant catarrhal fever.

Established lymphoblastoid cell lines with natural killer cell-like activity have been derived from cattle and deer affected with malignant catarrhal fever. They were examined phenotypically using monoclonal antibodies chosen for their cross-reactivity with peripheral blood lymphocytes from these species. Cell lines established from three of four cattle were identified as cytotoxic/suppressor lymphocytes (CD4-/CD8+/T19-) whilst the other was shown to be of the helper cell phenotype (CD4+/CD8-/T19-). Two other cell lines, one derived from a red deer and the other from a Père David's deer, were both CD4-/CD8-/T19. All of the lines examined expressed a T cell receptor (CD2+).     

The replication of canine herpesvirus (CHV) induces apoptosis in canine kidney cell line: short communication

The alphaherpesvirus canine herpesvirus (CHV) was tested in order to determine whether or not it has apoptotic potential. We have demonstrated that lytic replication of CHV resulted in induction of apoptosis. This phenomenon was confirmed using different techniques including in situ TUNEL assay and DNA laddering. The apoptotic activity of CHV might influence the pathobiology of this virus.