Conservation of endangered species through somatic cell nuclear transfer (SCNT)

Serum starvation as the most suitable method for inducing G0/G1 phase cell cycle arrest in six-banded armadillo (Euphractus sexcinctus) skin-derived fibroblast lines

BACKGROUND

Several studies have evaluated different cell cycle synchronization methods to improve reprogramming efficiency aimed at wild species conservation. The six-banded armadillo is one of the wild mammals with significant ecological and biomedical interests but has not yet been evaluated for reprogramming purposes.

OBJECTIVE

We investigated the effects in a time-dependent manner of serum starvation (SS; 0.5 % serum), contact inhibition (CI), and roscovitine (RSV 15 and 30 µM) on the cycle synchronization at G0/G1 phase of six-banded armadillo fibroblasts by flow cytometric analysis.

METHODS

The morphology, viability, and apoptosis levels were determined by microscopic analysis.

RESULTS

The results showed that SS significantly increased the percentage of cells arrested in the G0/G1 phase in a time-dependent manner, where SS for 72 h (90.5 % ± 0.8) and 120 h (90.1 % ± 0.9) showed the highest value compared to SS for 24 h (86.1 % ± 0.9) and control group (69.7 % ± 0.8; P<0.05). However, neither CI nor RSV exposure significantly increased the arrest of fibroblasts at the G0/G1 phase under any of the evaluated conditions (P>0.05). In contrast to SS and RSV, CI significantly induced necrosis, as evidenced by an increase in dead cells (P < 0.05) over the evaluated periods, thereby disrupting the synchronization efforts. Moreover, all methods demonstrated similar morphology and cell viability rates over the evaluated times, as assessed by the trypan blue exclusion assay.

CONCLUSION

These results indicated that SS was the most suitable method for cell cycle modulation in G0/G1 of six-banded armadillo fibroblasts, especially after 72-120 h of treatment. This finding has significant implications for future reprogramming efforts and conservation strategies for this unique species, as effective cell cycle synchronization can enhance the success of techniques, such as cloning and generation of induced cells to pluripotency.

Cryopreservation and passaging optimization for Galea spixii (Wagler, 1831) adult skin fibroblast lines: A step forward in species management and genetic studies

BACKGROUND

In vitro culture of fibroblasts is a technique based on cell isolation, physiological characterization, and cryopreservation. This technique has not been described for Galea spixii, therefore, it can be used to learn about its cellular biology and genetic diversity.

OBJECTIVE

We established fibroblast lines of six G. spixii individuals from several passages (second, fifth, eighth, and tenth) and cryopreserved them.

METHODS

Fibroblasts recovered from skin biopsies were identified based on morphology, immunocytochemistry, and karyotyping. The cells were analyzed for morphology, ultrastructure, viability, proliferation, metabolism, oxidative stress, bioenergetic potential, and apoptosis before and after cryopreservation.

RESULTS

After the eighth passage, the fibroblasts showed morphological and karyotypic changes, although their viability, metabolism, and proliferation did not change. An increase in oxidative stress and bioenergetic potential from the fifth to the eighth passages were also observed. Post cryopreservation, cell damage with respect to the ultrastructure, viability, proliferative rate, apoptotic levels, oxidative stress, and bioenergetic potential were verified.

CONCLUSION

Fibroblasts up to the tenth passage could be cultured in vitro. However, cells at the fifth passage were of better quality to be used for reproductive techniques. Additionally, optimization of the cryopreservation protocol is essential to improve the physiological parameters of these cells.

Establishment and Characterization of a Primary Fibroblast Cell Culture from the Amazonian Manatee (Trichechus inunguis)

The vulnerable status of the Amazon manatee, Trichechus inunguis, indicates the need to seek measures to guarantee its conservation. In this context, the cultivation of cells in vitro is a strategy that should at least guarantee the preservation of their genetic material. Thus, we established for the first time a primary culture of Amazonian manatee fibroblasts (TINsf) from a skin biopsy of a young male. Karyotypic analysis of the 3rd, 7th, and 12th passages confirmed the taxonomic identity of the species T. inunguis (2n = 56/NF = 92) and indicated that this culture presents genomic stability. Gene and protein expression of vimentin at the 13th passage show the predominant presence of fibroblasts in TINsf. To test the cell line's responsiveness to materials and demonstrate a possible application of this culture, it was exposed to andiroba seed oil (ASO), and its viability and proliferative capacity were evaluated. ASO demonstrated toxic effects at the highest concentrations and longest exposure times tested, reproducing results observed in human cultures, indicating the applicability of TINsf in toxicological and biotechnological studies. After cryopreservation, the TINsf line maintained its proliferative potential, indicating the establishment of a new culture available for future studies.

Establishment of Primary Adult Skin Fibroblast Cell Lines from African Savanna Elephants (Loxodonta africana)

Following population declines of the African savanna elephant (Loxodonta africana) across the African continent, the establishment of primary cell lines of endangered wildlife species is paramount for the preservation of their genetic resources. In addition, it allows molecular and functional studies on the cancer suppression mechanisms of elephants, which have previously been linked to a redundancy of tumor suppressor gene TP53. This methodology describes the establishment of primary elephant dermal fibroblast (EDF) cell lines from skin punch biopsy samples (diameter: ±4 mm) of African savanna elephants (n = 4, 14-35 years). The applied tissue collection technique is minimally invasive and paves the way for future remote biopsy darting. On average, the first explant outgrowth was observed after 15.75 ± 6.30 days. The average doubling time (Td) was 93.02 ± 16.94 h and 52.39 ± 0.46 h at passage 1 and 4, respectively. Metaphase spreads confirmed the diploid number of 56 chromosomes. The successful establishment of EDF cell lines allows for future elephant cell characterization studies and for research on the cancer resistance mechanisms of elephants, which can be harnessed for human cancer prevention and treatment and contributes to the conservation of their genetic material.

Strategies for establishing and using genome resource banks to protect genetic diversity in conservation breeding programs

Genome resource banks (GRBs) have the potential to preserve the genetic diversity of a species over time, yet they are rarely utilized as effective components of conservation breeding programs. Advances have been made in reproductive biology, collection and storage techniques, and use of stored gametes for achieving successful reproduction, but there are few guidelines for integrating GRBs into established breeding programs. Here we present basic guidelines, focusing on strategies for the collection, maintenance, and use of semen GRBs for protecting genetic diversity. These guidelines should be applied in the context of the specific purposes and roles of a breeding program's GRB, which will differ among species depending on vulnerability to loss and the status of rescue and conservation efforts. We recommend establishing up to three types of collections: (1) a National Reserve to preserve a species' genetic diversity, to be used only as a last resort; (2) a Savings Account to be used periodically to invigorate a genetically depauperate population; and (3) a Checking Account to be used as a regular part of the breeding program. We present methods for identifying donors to maximize genetic diversity in a GRB, as well as strategies for maintaining and optimally using GRBs.

Oocyte Penetration Speed Optimization Based on Intracellular Strain

Oocyte penetration is an essential step for many biological technologies, such as animal cloning, embryo microinjection, and intracytoplasmic sperm injection (ICSI). Although the success rate of robotic cell penetration is very high now, the development potential of oocytes after penetration has not been significantly improved compared with manual operation. In this paper, we optimized the oocyte penetration speed based on the intracellular strain. We firstly analyzed the intracellular strain at different penetration speeds and performed the penetration experiments on porcine oocytes. Secondly, we studied the cell development potential after penetration at different penetration speeds. The statistical results showed that the percentage of large intracellular strain decreased by 80% and the maximum and average intracellular strain decreased by 25-38% at the penetration speed of 50 μm/s compared to at 10 μm/s. Experiment results showed that the cleavage rates of the oocytes after penetration increased from 65.56% to 86.36%, as the penetration speed increased from 10 to 50 μm/s. Finally, we verified the gene expression of oocytes after penetration at different speeds. The experimental results showed that the totipotency and antiapoptotic genes of oocytes were significantly higher after penetration at the speed of 50 μm/s, which verified the effectiveness of the optimization method at the gene level.

The Role of Ca2 + in Maturation and Reprogramming of Bovine Oocytes: A System Study of Low-Calcium Model

[Ca²⁺]_i is essential for mammalian oocyte maturation and early embryonic development, as those processes are Ca²⁺ dependent. In the present study, we investigated the effect of [Ca²⁺]_i on in vitro maturation and reprogramming of oocytes in a lower calcium model of oocyte at metaphase II (MII) stage, which was established by adding cell-permeant Ca²⁺ chelator BAPTA-AM to the maturation medium. Results showed that the extrusion of the first polar body (PB1) was delayed, and oocyte cytoplasmic maturation, including mitochondrial and endoplasmic reticulum distribution, was impaired in lower calcium model. The low-calcium-model oocytes presented a poor developmental phenotype of somatic cell nuclear transfer (SCNT) embryos at the beginning of activation of zygotic genome. At the same time, oxidative stress and apoptosis were observed in the low-calcium-model oocytes; subsequently, an RNA-seq analysis of the lower-calcium-model oocytes screened 24 genes responsible for the poor oocyte reprogramming, and six genes (ID1, SOX2, DPPA3, ASF1A, MSL3, and KDM6B) were identified by quantitative PCR. Analyzing the expression of these genes is helpful to elucidate the mechanisms of [Ca²⁺]_i regulating oocyte reprogramming. The most significant difference gene in this enriched item was ID1. Our results showed that the low calcium might give rise to oxidative stress and apoptosis, resulting in impaired maturation of bovine oocytes and possibly affecting subsequent reprogramming ability through the reduction of ID1.