Isolation, culture and characterization of a primary fibroblast cell line from channel catfish

Cryopreservation of Iranian Markhoz goat fibroblast cells as an endangered national genetic resource

Background

The continuous accessibility of local animals for sustainable use is being eroded annually. Thus, a strategic vision for the conservation of biodiversity is of far-reaching emphasis to deal with unprecedented challenges in the local population extension facing in the future. This study aimed to establish and cryopreserve endangered Markhoz goat (Capra hircus) fibroblast cell lines in vitro.

Methods and results

These primary fibroblast cells were isolated from 58 Iranian Markhoz goats and individually cultured by explant technique in DMEM medium supplemented with 10% FBS and 2 mM L-Glutamine, in the presence of Penicillin (200 U/ml)—Streptomycin (200 mg/ml) during the first passage number. The extracted cell lines were confirmed morphologically as fibroblast cells. The population doubling time for DMEM-cultured cells was 23 ± 0.5 h. Chromosomal analysis indicated a total chromosome number of 2n = 60 with > 95% frequency. The cultured cells were checked for bacteria, fungi, yeast, and mycoplasma contaminations and the results were reported negative. The efficiencies of the fluorescent protein encoded by VSV-G (pMDG) and lentiviral pCSGW vectors reported in a range of 65% value. According to the species identification analysis, the goat cell lines were banked and confirmed without any miss- and cross-contamination.

Conclusions

The significant issue in this paper can be concluded about the first report of the establishment of endangered Markhoz goat cell banking inside the country. This study demonstrated the successful establishment of a genetically stable fibroblast bank as a valuable genetic resource for the endangered Iranian Markhoz goat breed.

Molecular cytogenetic analysis and the establishment of a cell culture in the fish species Hollandichthys multifasciatus (Eigenmann & Norris, 1900) (Characiformes, Characidae)

Hollandichthys is a fish genus of the family Characidae that was until recently considered to be monotypic, with cytogenetic, morphological, and molecular data being restricted to a few local populations. In the present study, the karyotype of a population of Hollandichthys multifasciatus was analyzed using classical and molecular cytogenetic approaches for the investigation of potential markers that could provide new perspectives on the cytotaxonomy. H. multifasciatus presented a diploid number of 2n=50 chromosomes and a karyotype formula of 8m+10sm+32st. A single pair of chromosomes presented Ag-NORs signals, which coincided with the 18S rDNA sites visualized by FISH, whilst the 5S rDNA sequences were mapped in two chromosome pairs. The distribution of the U snRNA genes was mapped on the Hollandichthys chromosomes for the first time, with the probes revealing the presence of the U1 snDNA on the chromosomes of pair 20, U2 on pairs 6 and 19, U4 on pair 16, and U6 on the chromosomes of pair 11. The results of the present study indicated karyotypic differences in comparison with the other populations of H. multifasciatus studied previously, reinforcing the need for further research to identify isolated populations or the potential existence of cryptic Hollandichthys species.

New Protocol for Cell Culture to Obtain Mitotic Chromosomes in Fishes

Cell culture is an excellent alternative for the maintenance of cell lines and to obtain quality chromosome preparations of fishes. However, this methodology is still little employed, mainly because of the difficulty of standardization of cell cultures. In this study, we describe a methodology for the rapid acquisition of cell lineages and mitotic chromosomes for cytogenetic studies of fish species from muscle tissue cells. Our methodology is based on the use of a gelatin film, which provides better adhesion of a large number of cells and appropriate conditions for multiplication. The cells of Astyanax altiparanae, used as an experimental model, with fibroblast-like morphology, showed rapid cellular proliferation, resulting in a great number of cells. Chromosomal preparations of cultured cells showed the diploid number of the species, 2n = 50 chromosomes, in 80% of the cells examined, with chromosomes intact and distended. Cell populations were cryopreserved and after being recovered, these cells maintained their proliferative capacity. The development of this methodology represents an innovation for the fish cytogenetics area and it may bring a significant contribution to the conservation and study of several groups due to the difficulty of obtaining good-quality chromosome preparations.

Stabilization of gene expression and cell morphology after explant recycling during fin explant culture in goldfish

The development of fin primary cell cultures for in vitro cellular and physiological studies is hampered by slow cell outgrowth, low proliferation rate, poor viability, and sparse cell characterization. Here, we investigated whether the recycling of fresh explants after a first conventional culture could improve physiological stability and sustainability of the culture. The recycled explants were able to give a supplementary cell culture showing faster outgrowth, cleaner cell layers and higher net cell production. The cells exhibited a highly stabilized profile for marker gene expression including a low cytokeratin 49 (epithelial marker) and a high collagen 1a1 (mesenchymal marker) expression. Added to the cell spindle-shaped morphology, motility behavior, and actin organization, this suggests that the cells bore stable mesenchymal characteristics. This contrast with the time-evolving expression pattern observed in the control fresh explants during the first 2 weeks of culture: a sharp decrease in cytokeratin 49 expression was concomitant with a gradual increase in col1a1. We surmise that such loss of epithelial features for the benefit of mesenchymal ones was triggered by an epithelial to mesenchymal transition (EMT) process or by way of a progressive population replacement process. Overall, our findings provide a comprehensive characterization of this new primary culture model bearing mesenchymal features and whose stability over culture time makes those cells good candidates for cell reprogramming prior to nuclear transfer, in a context of fish genome preservation.

Establishment of glass catfish (Kryptopterus bicirrhis) fin-derived cells

Genetically manipulated transparent animals were already explored in many species for in vivo study of gene expression, transplantation analysis and cancer biology. However, there are no reports about transparent animals as in vitro genetic resources. In the present study, fin-derived cells from glass catfish (Krytopterus bicirrhis), naturally transparent fish with a visible skeleton and internal organs, were isolated after culturing fin explants and characterized using cryopreservation and cell cycle analysis. The cells grew well in DMEM (Dulbecco's modified Eagle's medium) containing 1% (v/v) P/S (penicillin–streptomycin) and 10% (v/v) fetal bovine serum at 26°C and showed increased cryopreservation efficiency with the slow-freezing method in the presence of 15% dimethyl sulfoxide. In addition, cell cycle analysis was evaluated based on flow cytometric analysis, and culturing to confluence (>85%) was more effective for synchronizing cells at the G₀/G₁ stages than roscovitine treatment (<75%). This is the first report about cell isolation from transparent animals. The results from testing the cell's viability following cryopreservation and subjecting the cells to cycle analysis can be useful tools for genetic resource management.

A simple non-invasive protocol to establish primary cell lines from tail and toe explants for cytogenetic studies in Australian dragon lizards (Squamata: Agamidae)

Primary cell lines were established from cultures of tail and toe clips of five species of Australian dragon lizards: Tympanocryptis pinguicolla, Tympanocryptis sp., Ctenophorus fordi, Amphibolurus norrisi and Pogona vitticeps. The start of exponential cell growth ranged from 1 to 5 weeks. Cultures from all specimens had fibroblastic morphology. Cell lines were propagated continuously up to ten passages, cryopreserved and recovered successfully. We found no reduction in cell viability after short term (<6 months) storage at -80 degrees C. Mitotic metaphase chromosomes were harvested from these cell lines and used in differential staining, banding and fluorescent in situ hybridisation. Cell lines maintained normal diploidy in all species. This study reports a simple non-invasive method for establishing primary cell lines from Australian dragon lizards without sacrifice. The method is likely to be applicable to a range of species. Such cell lines provide a virtually unlimited source of material for cytogenetic, evolutionary and genomic studies.

Characterization of goldfish fin cells in culture: some evidence of an epithelial cell profile

Comprehensive characterization of cultured cells in fish was little explored and cell origin is often deduced from morphological analogies with either epithelial of fibroblastic cells. This study aims to characterize cell origin in goldfish fin culture using morphological, immunochemical, and molecular approaches. Time lapse analysis revealed that cultured cell morphology changed within minutes. Therefore, cell morphology cannot predict whether cells are from fibroblastic or epithelial origin. The labeling pattern of heterologous anti-cytokeratin and anti-vimentin antibodies against goldfish epithelial cells and fibroblasts was first tested on skin sections and the corresponding labeling of the cultured cells was analyzed. No cell origin specificity could be obtained with the chosen antibodies. In the molecular approach, detection levels of three cytokeratin (CauK8-IIS, CauK49-IE and CauK50-Ie) and one vimentin transcripts were assessed on skin and fin samples. Specificity for epithelial cells of the most abundant mRNA, CauK49-Ie, was thereafter validated on skin sections by in situ hybridization. The selected markers were used afterwards to characterize fin cultures. CauK49-IE riboprobe labeled every cell in young cultures whereas no labeling was observed in older cultures. Accordingly, CauK49-IE transcript levels decreased after 15 days culture while CauK8-IIS ones increased. The use of homologous marker gave evidence that young cultured cells from goldfish fin are homogeneously of epithelial type and that cell characteristics may change over culture time.

Cryobanking of fish somatic cells: Optimizations of fin explant culture and fin cell cryopreservation

When gametes or embryos are not available, somatic cells should be considered for fish genome cryobanking of valuable or endangered fish. The objective of this work was to develop a method for fin explant culture with an assessed reliability, and to assess fin cells ability to cryopreservation. Anal fins from goldfish (Carassius auratus) were minced and gently loosened with collagenase before explants were plated at 20 degrees C in L-15 medium supplemented with fetal bovine serum and pH buffering additives. Quantification of cell-donor explants per fin rated the culture success. Cells were successfully obtained from every cultured anal fin (mean = 65% cell-donor explant per fin). All other fin types were suitable except the dorsal fin. Explant plating could be deferred 3 days from fin collecting. Fins from seven other fish species were successfully cultured with the method. After 2-3 weeks, sub-confluent fin cells from goldfish were cryopreserved. Cryopreservation with dimethyl sulfoxide and sucrose at a slow freezing rate allowed the recovery of half the goldfish fin cells. Cells displayed the same viability as fresh ones. 1,2-propanediol was unsuitable when a fast freezing rate was used. The procedure could now be considered for cryobanking with only minimal adaptation to each new species.

Inducible expression of green fluorescent protein within channel catfish cells by a cecropin gene promoter

The activity of an insect promoter of the cecropin B gene (Cec B) was investigated using green fluorescent protein (gfp) as a reporter in cells of channel catfish (Ictalurus punctatus). The expression vector pQZ-1 containing the Cec B promoter and a modified gfp cDNA sequence was delivered by lipofection to three catfish types: fibroblast and leukocyte cell lines, and primary cultures of leukocytes. No resistance genes were included in the vector for selection of GFP-expressing cells. The GFP mRNA was detected in all three cell types with 5 to 10 times higher concentrations observed in leukocytes than in fibroblasts. Expression was enhanced with the addition of irradiated Flavobacterium columnare (7.0 ¿10(6) cells/ml) or Escherichia coli LPS (125microgram/ml). Quantitative RT-PCR showed GFP mRNA reached maximum levels 24h after bacterial challenge in fibroblast cells, and at 10-12h after LPS challenge in fibroblasts and leukocytes. The number of fibroblasts expressing GFP increased by 0.8%, and the average of green fluorescence intensity increased by 52.8%, whereas the increase in leukocytes was 0.13% in cell number and 3.4% in fluorescence intensity. These results suggest that the transcription of the Cec B promoter in channel catfish cells exhibited an inducible pattern and could be placed under the control of the immune system (in vivo). The mechanisms for endogenous activation of the Cec B promoter and for production of gfp RNA in unchallenged cells remain to be studied.