Gamete and cell technologies for use in biological resource banking

Biological resource banking is becoming important for endangered species conservation. A series of experiments were conducted to address issues concerning collection and utilization of biomaterials from Gulf Coast Native (GCN) sheep (model species) (Ovis aries) and Eland antelope (Taurotragus oryx). In the first experiment, two ejaculates were collected 10 minutes apart from each of five rams three times a week for three weeks to maximize output and minimize handling time. Semen volume, concentration and total number of spermatozoa were significantly greater in first ejaculates, whereas pre-cooled, cooled and post-thaw motility, as well as sperm survival, were greater in second ejaculates. The second experiment was designed to develop a practical method for freezing skin biopsies for tissue culture. Cell survival was enhanced by an equilibration time of at least 15 minutes in biological media (containing blood or serum) as compared to non-biological medium (containing PVP). Then, the possibility of using semen and cooled milk as sources of somatic cells (SC) for in vitro culture was evaluated. Fresh, cooled and cryopreserved semen from rams and fresh eland semen was cultured and although SC plated, proliferation was low. From milk, cell attachment was observed in 92% of the samples, whereas only 38% proliferated in culture. Therefore, the ensuing experiment was focused on increasing in vitro proliferation of semen-derived SC by developing (1) a Percoll gradient technique to separate SC from spermatozoa before culture and (2) a method for co-culture of isolated SC with inactivated mouse fibroblasts. Proliferation was significantly increased by co-culture, but contact between the semen-derived SC and feeder cells was not necessary. Finally, intergeneric nuclear transfer (igNT) of semen-derived eland epithelial cells into bovine cytoplasts showed that these cells could direct early embryonic development up to the 8-cell stage. Determination of BrdU-incorporation and evaluation of nuclear status revealed that initial remodeling of the eland nucleus was similar to that of bovine NT embryos within the first 16 hours post-activation; however, after 84 hours, only 13% of interspecies embryos had cycling nuclei in their blastomeres. Future improvements in the technology should eventually allow cloned offspring to be produced from semen-derived somatic cells

3D genomics across the tree of life reveals condensin II as a determinant of architecture type

We investigated genome folding across the eukaryotic tree of life. We find two types of three-dimensional(3D) genome architectures at the chromosome scale. Each type appears and disappears repeatedlyduring eukaryotic evolution. The type of genome architecture that an organism exhibits correlates with theabsence of condensin II subunits. Moreover, condensin II depletion converts the architecture of thehuman genome to a state resembling that seen in organisms such as fungi or mosquitoes. In this state,centromeres cluster together at nucleoli, and heterochromatin domains merge. We propose a physicalmodel in which lengthwise compaction of chromosomes by condensin II during mitosis determineschromosome-scale genome architecture, with effects that are retained during the subsequent interphase.This mechanism likely has been conserved since the last common ancestor of all eukaryotes.C.H. is supported by the Boehringer Ingelheim Fonds; C.H., Á.S.C., and B.D.R. are supported by an ERC CoG (772471, “CohesinLooping”); A.M.O.E. and B.D.R. are supported by the Dutch Research Council (NWO-Echo); and J.A.R. and R.H.M. are supported by the Dutch Cancer Society (KWF). T.v.S. and B.v.S. are supported by NIH Common Fund “4D Nucleome” Program grant U54DK107965. H.T. and E.d.W. are supported by an ERC StG (637597, “HAP-PHEN”). J.A.R., T.v.S., H.T., R.H.M., B.v.S., and E.d.W. are part of the Oncode Institute, which is partly financed by the Dutch Cancer Society. Work at the Center for Theoretical Biological Physics is sponsored by the NSF (grants PHY-2019745 and CHE-1614101) and by the Welch Foundation (grant C-1792). V.G.C. is funded by FAPESP (São Paulo State Research Foundation and Higher Education Personnel) grants 2016/13998-8 and 2017/09662-7. J.N.O. is a CPRIT Scholar in Cancer Research. E.L.A. was supported by an NSF Physics Frontiers Center Award (PHY-2019745), the Welch Foundation (Q-1866), a USDA Agriculture and Food Research Initiative grant (2017-05741), the Behavioral Plasticity Research Institute (NSF DBI-2021795), and an NIH Encyclopedia of DNA Elements Mapping Center Award (UM1HG009375). Hi-C data for the 24 species were created by the DNA Zoo Consortium (www.dnazoo.org). DNA Zoo is supported by Illumina, Inc.; IBM; and the Pawsey Supercomputing Center. P.K. is supported by the University of Western Australia. L.L.M. was supported by NIH (1R01NS114491) and NSF awards (1557923, 1548121, and 1645219) and the Human Frontiers Science Program (RGP0060/2017). The draft A. californica project was supported by NHGRI. J.L.G.-S. received funding from the ERC (grant agreement no. 740041), the Spanish Ministerio de Economía y Competitividad (grant no. BFU2016-74961-P), and the institutional grant Unidad de Excelencia María de Maeztu (MDM-2016-0687). R.D.K. is supported by NIH grant RO1DK121366. V.H. is supported by NIH grant NIH1P41HD071837. K.M. is supported by a MEXT grant (20H05936). M.C.W. is supported by the NIH grants R01AG045183, R01AT009050, R01AG062257, and DP1DK113644 and by the Welch Foundation. E.F. was supported by NHGR

Cloned embryos from semen. Part 2: Intergeneric nuclear transfer of semen-derived eland (Taurotragus oryx) epithelial cells into bovine oocytes

The production of cloned offspring by nuclear transfer (NT) of semen-derived somatic cells holds considerable potential for the incorporation of novel genes into endangered species populations. Because oocytes from endangered species are scarce, domestic species oocytes are often used as cytoplasts for interspecies NT. In the present study, epithelial cells isolated from eland semen were used for intergeneric transfer (IgNT) into enucleated bovine oocytes and compared with bovine NT embryos. Cleavage rates of bovine NT and eland IgNT embryos were similar (80 vs. 83%, respectively; p \u3e 0.05); however, development to the morula and blastocyst stage was higher for bovine NT embryos (38 and 21%, respectively; p \u3c 0.0001), than for eland IgNT embryos (0.5 and 0%, respectively). DNA synthesis was not observed in either bovine NT or eland IgNT cybrids before activation, but in 75 and 70% of bovine NT and eland igNT embryos, respectively, cell-cycle resumption was observed at 16 h postactivation (hpa). For eland IgNT embryos, 13% had ≥8 cells at 84 hpa, while 32% of the bovine NT embryos had ≥8 cells at the same interval. However, 100 and 66% of bovine NT and eland IgNT embryos, respectively, that had ≥8 cells synthesized DNA. From these results we concluded that (1) semen-derived epithelial cell nuclei can interact and be transcriptionally controlled by bovine cytoplast, (2) the first cell-cycle occurred in IgNT embryos, (3) a high frequency of developmental arrest occurs before the eight-cell stage in IgNT embryos, and (4) IgNT embryos that progress through the early cleavage stage arrest can (a) synthesize DNA, (b) progress through subsequent cell cycles, and (c) may have the potential to develop further. © 2008 Mary Ann Liebert, Inc

Cloned embryos from semen. Part 1: In vitro proliferation of epithelial cells on embryonic fibroblasts after isolation from semen by gradient centrifugation

Although epithelial-like somatic cells have been previously isolated from semen, cell proliferation rates were low. Culture of whole semen samples resulted in loss of potentially valuable spermatozoa. The aims of the present study were to (1) isolate somatic cells from semen, while preserving sperm viability, and (2) optimize in vitro culture conditions for semen-derived epithelial cells. Density gradient centrifugation of washed ejaculates of two rams (Ovis aries) (n = 24) and one eland bull (Taurotragus oryx) (n = 4) was performed using a three-layer discontinuous Percoll column consisting of 90% (P-90), 50% (P-50), and 20% (P-20) Percoll. In vitro culture and Trypan Blue staining indicated that live somatic cells settled in the P-20 layer. Nonmotile spermatozoa were recovered at the P-50 and P-90 interfaces, whereas motile spermatozoa were collected in the pellet from the P-90 layer. Subsequently, somatic cells isolated from the P-20 layer were plated either on inactivated 3T3 mouse embryonic fibroblast feeder layers, collagen-coated plates with 3T3 feeder cell inserts, or on collagen-coated plates. Initial somatic cell plating was similar among treatments, but proliferation significantly increased when cocultured with 3T3 cells (feeder or insert). Furthermore, two different types of epithelial cells were obtained. The exact origin of the cells in the male reproduction system is uncertain and probably variable. The present method of cell isolation and in vitro culture may be of value for preserving endangered species. Specifically, cells isolated and cultured from cryopreserved semen of nonliving males could be used for producing embryos by somatic cell nuclear transfer. © 2008 Mary Ann Liebert, Inc

In vitro fertilization and andrology laboratory in 2030: expert visions

: The aim of this article is to gather 9 thought leaders and their team members to present their ideas about the future of in vitro fertilization and the andrology laboratory. Although we have seen much progress and innovation in the laboratory over the years, there is still much to come, and this article looks at what these leaders think will be important in the future development of technology and processes in the laboratory