Evaluation of fertilization capability of frozen-thawed completely immotile spermatozoa collected from a white bengal tiger after interspecific ICSI with bovine oocytes.

The objective of this study was to evaluate the fertilization capability of White Bengal Tiger frozen-thawed completely immotile spermatozoa after interspecific intracytoplasmic sperm injection (ICSI) with bovine oocytes. The fertilization status of presumptive zygotes was assessed 18 h after ICSI by immunofluorescence staining and confocal microscopy. The fertilization rate was 34.8% (8/23), as confirmed by the extrusion of two polar bodies, or male and female pronuclei formation. For unfertilized oocytes (65.2%, 15/23), one activated oocyte had an activated spermatozoon but most were unactivated oocytes with unactivated spermatozoa (1/15, 6.7% vs 10/15, 66.7%, respectively, p < 0.05). These results showed that White Bengal Tiger frozen-thawed completely immotile spermatozoa retained the capacity to fertilize bovine oocytes after interspecific ICSI. This is the first report of in vitro produced zygotes using tiger immotile sperm with bovine oocytes by interspecific ICSI technique, which provides an efficient and feasible method for preservation and utilization of endangered feline animals.

Evaluation of fertilization capability of frozen-thawed completely immotile spermatozoa collected from a white bengal tiger after interspecific ICSI with bovine oocytes

The objective of this study was to evaluate the fertilization capability of White Bengal Tiger frozen-thawed completely immotile spermatozoa after interspecific intracytoplasmic sperm injection (ICSI) with bovine oocytes. The fertilization status of presumptive zygotes was assessed 18 h after ICSI by immunofluorescence staining and confocal microscopy. The fertilization rate was 34.8% (8/23), as confirmed by the extrusion of two polar bodies, or male and female pronuclei formation. For unfertilized oocytes (65.2%, 15/23), one activated oocyte had an activated spermatozoon but most were unactivated oocytes with unactivated spermatozoa (1/15, 6.7% vs 10/15, 66.7%, respectively, p < 0.05). These results showed that White Bengal Tiger frozen-thawed completely immotile spermatozoa retained the capacity to fertilize bovine oocytes after interspecific ICSI. This is the first report of in vitro produced zygotes using tiger immotile sperm with bovine oocytes by interspecific ICSI technique, which provides an efficient and feasible method for preservation and utilization of endangered feline animals.(AU)

Intraspecific genetic divergence within Helianthus niveus and the status of two new morphotypes from Mexico.

PREMISE: Collecting and characterizing the genetic diversity of wild relatives of crops can contribute importantly to sustainable crop production and food security. Wild sunflower, Helianthus niveus, occurs in arid regions in western North America and is partially cross-compatible with the cultivated sunflower (H. annuus). We assessed phylogenetic relationships and patterns of genetic divergence among three previously described subspecies (subsp. niveus, subsp. canescens, and subsp. tephrodes) as well as two new morphotypes of H. niveus recently discovered in extreme drought and dune habitats in Baja California, Mexico. METHODS: We measured 50 plants growing in a common garden for 27 morphological traits and conducted principal component analysis to assess patterns of phenotypic variation. Genome size of each accession was determined using flow cytometry. Pollen viability of first generation hybrids between taxa was tested to infer the strength of intrinsic postzygotic reproductive barriers. Finally, genotyping-by-sequencing data were used to investigate the genetic structure and phylogenetic relationships among the previously described subspecies and new morphotypes. RESULTS: The intraspecific genetic and phenotypic divergence of H. niveus populations closely tracks their geographical distribution. Subspecies niveus is phenotypically, genetically, and reproductively distinct from the other two subspecies and has a larger genome. Therefore, H. niveus as currently circumscribed should be considered to contain two distinct species, H. niveus and H. tephrodes. ABBA-BABA tests revealed substantial introgression between subsp. canescens and its sympatric congener H. petiolaris, which might contribute to their morphological similarities. The two new morphotypes collected in Mexico represent local ecotypes of subsp. niveus that occur in extreme drought and dune environments. Mantel tests showed a strong positive correlation between genetic and geographic distances. CONCLUSIONS: We conclude that geographic isolation is primarily responsible for intraspecific genomic divergence within H. niveus, while patterns of phenotypic variation appear to have been shaped by ecological selection and interspecific introgression.