Description of a new octoploid frog species (Anura: Pipidae: Xenopus) from the Democratic Republic of the Congo, with a discussion of the biogeography of African clawed frogs in the Albertine Rift.

We describe a new octoploid species of African clawed frog (Xenopus) from the Lendu Plateau in the northern Albertine Rift of eastern Democratic Republic of the Congo. This species is the sister taxon of Xenopus vestitus (another octoploid), but is distinguished by a unique morphology, vocalization and molecular divergence in mitochondrial and autosomal DNA. Using a comprehensive genetic sample, we provide new information on the species ranges and intra-specific diversity of African clawed frogs from the Albertine Rift, including the details of a small range extension for the critically endangered Xenopus itombwensis and previously uncharacterized variation in Xenopus laevis. We also detail a new method for generating cytogenetic preparations in the field that can be stored at room temperature for up to 3 weeks. While extending our understanding of the extant diversity in the Albertine Rift, this new species highlights components of species diversity in ancestral African clawed frogs that are not represented by known extant descendants.

Incidence of chromosomal abnormalities in bovine blastocysts derived from unsorted and sex-sorted spermatozoa.

The aim of the present study was to examine the incidence of chromosomal abnormalities in bovine blastocysts produced by IVF with unsorted, X-sorted or Y-sorted spermatozoa. In Experiment 1, individual blastocysts were processed to examine the incidence of mixoploidy using fluorescent in situ hybridisation. Overall, 80% (44/55) of blastocysts were mixoploid (10/15, 14/15 and 20/25 for X-sorted, Y-sorted and unsorted spermatozoa, respectively; P > 0.05). However, the prevalence of abnormal XY chromosome complements was relatively low in all groups; on average, only a small fraction of the total nuclei per embryo appeared polyploid (1.64%, 5.62% and 6.0% for X-sorted, Y-sorted and unsorted spermatozoa, respectively). Interestingly, 20% (5/25) of blastocysts derived from unsorted spermatozoa were found to be chimeric (XX/XY). In Experiment 2, chimeric embryos were detected among the blastocysts derived from two of five sires tested. In addition, one chimeric blastocyst was detected among nine in vivo-derived blastocysts obtained following AI. In conclusion, based on the results of the present study, the incidence of chromosomal abnormalities did not different between blastocysts derived from sex-sorted or unsorted spermatozoa. In addition, the occurrence of mixed sex chimeras was not limited to a single sire and was not unique to blastocysts derived from IVF.

Nucleolar organizer regions (NORs) distribution and behavior in spermatozoa and meiotic cells of the horse (Equus caballus).

Nucleolar organizing regions (NORs) containing rDNA gene clusters have been assigned to the equine autosomes ECA1, ECA28, and ECA31. Active NORs (Ag-NORs) are associated with argyrophilic proteins, which allow them to be readily identified using silver staining techniques. Fluorescence in situ hybridization (FISH) for rDNA can also be used to visualize all NOR clusters in the nucleus, regardless of whether they are active or inactive. The present study analyzed the distribution and behavior of equine Ag-NOR and NOR clusters in horse spermatozoa and during male meiosis by FISH and silver staining. The NOR foci were observed to be variable in number, size, and shape, but were usually located centrally and appeared as one or two nucleolus-like structures in the spermatozoa head. Three distinctive FISH signals identified the NOR-bearing chromosome pairs during the synaptic cell stage of meiosis I. At diakinesis/metaphase I, as well as different stages of meiosis II, FISH signals clearly depicted the NOR-bearing sister chromatids. The synaptonemal complexes of primary spermatocytes consistently showed three rDNA foci following FISH, but variably demonstrated two or three Ag-NOR bodies following silver staining. We propose rDNA loss and gain during unequal crossing-over events could be both a direct and indirect cause of variation in equine NOR foci. Additionally, our cytogenetic analysis did not confirm the presence of a fourth pair of NORs-bearing chromosomes in the horse, which is contrary to previously mitotic published data.

Directed differentiation of porcine epiblast-derived neural progenitor cells into neurons and glia.

Neural progenitor cells (NPCs) are promising candidates for cell-based therapy of neurodegenerative diseases; however, safety concerns must be addressed through transplantation studies in large animal models, such as the pig. The aim of this study was to derive NPCs from porcine blastocysts and evaluate their in-vitro differentiation potential. Epiblasts were manually isolated from expanded hatched blastocysts and cultured on MEF feeder cells. Outgrowth colonies were passaged to MS5 cells and rosettes were further passaged to Matrigel-coated dishes containing bFGF and EGF. Three NPC lines were established which showed expression of SOX2, NESTIN and VIMENTIN. One line was characterised in more detail, retaining a normal karyotype and proliferating for more than three months in culture. Following differentiation, TUJI was significantly up-regulated in protocol 2 (RA and SHH; 58% positive cells) as were NF and TH. In contrast, MBP was significantly up-regulated in protocol 3 (FGF8 and SHH; 63% positive cells), whereas, GFAP was significantly up-regulated in protocols 1-4 (33%, 25%, 43% and 22%). The present study provides the first report of a porcine blastocyst-derived NPC line capable of differentiating into both neurons and glia, which may be of paramount importance for future transplantation studies in large animal models of neurodegenerative diseases.