Biology of Reproduction
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Published By Oxford University Press

1529-7268, 0006-3363
Updated Tuesday, 21 September 2021

Author(s):  
Zoë E Kiefer ◽  
Lucas R Koester ◽  
Jamie M Studer ◽  
Amanda L Chipman ◽  
Christine Mainquist-Whigham ◽  
...  

Abstract During the last decade, sow mortality due to pelvic organ prolapse (POP) has increased. To better understand the biology associated with POP, sows were phenotypically assessed and assigned perineal scores (PS) based on presumed POP risk and categorized as PS1 (low), PS2 (moderate), or PS3 (high). The study objective was to identify changes in sow vaginal microbiota that may be associated with POP. The hypothesis is vaginal microbiota differs between sows with variable risk for POP, and changes in microbiota during late gestation exist between sows with differing risk. Of the 2864 sows scored during gestation week 15, 1.0%, 2.7%, and 23.4% of PS1, PS2, and PS3 sows, respectively, subsequently experienced POP. Vaginal swabs subjected to 16S rRNA gene sequencing revealed differences in community composition (Bray-Curtis; P < 0.05) and individual operational taxonomic unit (OTU) comparisons between vaginal microbiota of PS1 and PS3 sows at gestation week 15. Further, differences (P < 0.05) in community composition and OTUs (Q < 0.05) were observed in PS3 sows that either did or did not subsequently experience POP. Differences in community structure (alpha diversity measurements; P < 0.05), composition (P < 0.05) and OTUs (Q < 0.05) were observed in gestation week 12 sows scored PS1 compared to week 15 sows scored PS1 or PS3, suggesting sow vaginal microbiota shifts during late gestation differently as POP risk changes. Collectively, these data demonstrate sows with greater POP risk have unique vaginal microflora, for which a better understanding could aid in development of mitigation strategies.


Author(s):  
Dulama Richani ◽  
Robert B Gilchrist

Abstract Oocytes are maintained in a state of meiotic arrest following the first meiotic division until ovulation is triggered. Within the antral follicle, meiotic arrest is actively suppressed in a process facilitated by the cyclic nucleotides cGMP and cAMP. If removed from this inhibitory follicular environment and cultured in vitro, mammalian oocytes undergo spontaneous meiotic resumption in the absence of the usual stimulatory follicular stimuli, leading to asynchronicity with oocyte cytoplasmic maturation and lower developmental competence. For more than 50 years, pharmacological agents have been used to attenuate oocyte germinal vesicle (GV) breakdown in vitro. Agents which increase intra-oocyte cAMP or prevent its degradation have been predominantly used, however agents such as kinase and protein synthesis inhibitors have also been trialled. Twenty years of research demonstrates that maintaining GV arrest for a period before in vitro maturation (IVM) improves oocyte developmental competence, and is likely attributed to maintenance of bidirectional communication with cumulus cells leading to improved oocyte metabolic function. However, outcomes are influenced by various factors including the mode of action of the modulators, dose, treatment duration, species, and the degree of hormonal priming of the oocyte donor. Cyclic GMP and/or cAMP modulation in a prematuration step (called pre-IVM) prior to IVM has shown the greatest consistency in improving oocyte developmental competence, whereas kinase and protein synthesis inhibitors have proven less effective at improving IVM outcomes. Such pre-IVM approaches have shown potential to alter current use of artificial reproductive technologies in medical and veterinary practice.


Author(s):  
William C Lester ◽  
Taylor Johnson ◽  
Ben Hale ◽  
Nicholas Serra ◽  
Brian Elgart ◽  
...  

Abstract Aurora A kinase (AURKA) is an important regulator of cell division and is required for assembly of the mitotic spindle. We recently reported the unusual finding that this mitotic kinase is also found on the sperm flagellum. To determine its requirement in spermatogenesis, we generated conditional knockout animals with deletion of the Aurka gene in either spermatogonia or spermatocytes to assess its role in mitotic and postmitotic cells, respectively. Deletion of Aurka in spermatogonia resulted in disappearance of all developing germ cells in the testis, as expected given its vital role in mitotic cell division. Deletion of Aurka in spermatocytes reduced testis size, sperm count, and fertility, indicating disruption of meiosis or an effect on spermiogenesis in developing mice. Interestingly, deletion of Aurka in spermatocytes increased apoptosis in spermatocytes along with an increase in the percentage of sperm with abnormal morphology. Despite the increase in abnormal sperm, sperm from spermatocyte Aurka knockout mice displayed increased progressive motility. In addition, sperm lysate prepared from Aurka knockout animals had decreased protein phosphatase 1 (PP1) activity. Together, our results show that AURKA plays multiple roles in spermatogenesis, from mitotic divisions of spermatogonia to sperm morphology and motility.


Author(s):  
Sean M Cullen ◽  
Nora Hassan ◽  
Matthew Smith-Raska

Author(s):  
D E Goszczynski ◽  
P S Tinetti ◽  
Y H Choi ◽  
K Hinrichs ◽  
P J Ross

Abstract Embryonic genome activation is a critical event in embryo development, in which the transcriptional program of the embryo is initiated. The timing and regulation of this process are species-specific. In vitro embryo production is becoming an important clinical and research tool in the horse; however, very little is known about genome activation in this species. The objective of this work was to identify the timing of genome activation, and the transcriptional networks involved, in in vitro-produced horse embryos. RNA-Seq was performed on oocytes and embryos at eight stages of development (MII, zygote, 2-cell, 4-cell, 8-cell, 16-cell, morula, blastocyst; n = 6 per stage, 2 from each of 3 mares). Transcription of seven genes was initiated at the 2-cell stage. The first substantial increase in gene expression occurred at the 4-cell stage (minor activation), followed by massive gene upregulation and downregulation at the 8-cell stage (major activation). An increase in intronic nucleotides, indicative of transcription initiation, was also observed at the 4-cell stage. Co-expression network analyses identified groups of genes that appeared to be regulated by common mechanisms. Investigation of hub genes and binding motifs enriched in the promoters of co-expressed genes implicated several transcription factors. This work represents, to the best of our knowledge, the first genomic evaluation of embryonic genome activation in horse embryos.


Author(s):  
D E Goszczynski ◽  
P S Tinetti ◽  
Y H Choi ◽  
P J Ross ◽  
K Hinrichs

Abstract Embryonic genome activation and dosage compensation are major genetic events in early development. Combined analysis of single embryo RNA-seq data and parental genome sequencing was used to evaluate parental contributions to early development and investigate X-chromosome dynamics. In addition, we evaluated dimorphism in gene expression between male and female embryos. Evaluation of parent-specific gene expression revealed a minor increase in paternal expression at the 4-cell stage that increased at the 8-cell stage. We also detected eight genes with allelic expression bias that may have an important role in early development, notably NANOGNB. The main actor in X-chromosome inactivation, XIST, was significantly upregulated at the 8-cell, morula, and blastocyst stages in female embryos, with high expression at the latter. Sexual dimorphism in gene expression was identified at all stages, with strong representation of the X-chromosome in females from the 16-cell to the blastocyst stage. Female embryos showed biparental X-chromosome expression at all stages after the 4-cell stage, demonstrating the absence of imprinted X-inactivation at the embryo level. The analysis of gene dosage showed incomplete dosage compensation (0.5 < X:A < 1) in MII oocytes and embryos up to the 4-cell stage, an increase of the X:A ratio at the 16-cell and morula stages after genome activation, and a decrease of the X:A ratio at the blastocyst stage, which might be associated with the beginning of X-chromosome inactivation. This study represents the first critical analysis of parent- and sex-specific gene expression in early equine embryos produced in vitro.


Author(s):  
Subarna Sinha ◽  
Merrill Knapp ◽  
John Pywtorak ◽  
Greg McCain ◽  
Kenneth Wingerden ◽  
...  

Abstract The long and challenging drug development process begins with discovery biology for the selection of an appropriate target for a specific indication. Target is a broad term that can be applied to a range of biological entities such as proteins, genes and RNAs. Although there are numerous databases available for mining biological entities, publicly available searchable, downloadable databases to aid in target selection for a specific disease or indication (e.g. developing contraceptives and infertility treatments) are limited. We report the development of the Contraceptive Infertility Target DataBase (CITDBase: https://www.citdbase.org), which provides investigators an interface to mine existing transcriptomic and proteomic resources to identify high quality contraceptive/infertility targets. The creation of similar individualized databases is applicable to the identification of targets for other diseases and conditions.


Author(s):  
Jessica S Dudley ◽  
Christopher R Murphy ◽  
Michael B Thompson ◽  
Bronwyn M McAllan

Abstract There are many different forms of nutrient provision in viviparous (live bearing) species. The formation of a placenta is one method where the placenta functions to transfer nutrients from mother to fetus (placentotrophy), transfer waste from the fetus to the mother and respiratory gas exchange. Despite having the same overarching function, there are different types of placentation within placentotrophic vertebrates, and many morphological changes occur in the uterus during pregnancy to facilitate formation of the placenta. These changes are regulated in complex ways but are controlled by similar hormonal mechanisms across species. This review describes current knowledge of the morphological and molecular changes to the uterine epithelium preceding implantation among mammals. Our aim is to identify the commonalities and constraints of these cellular changes to understand the evolution of placentation in mammals and propose directions for future research. We compare and discuss the complex modifications to the ultrastructure of uterine epithelial cells and show that there are similarities in the changes to the cytoskeleton and gross morphology of the uterine epithelial cells, especially of the apical and lateral plasma membrane of the cells during the formation of a placenta in all eutherians and marsupials studied to date. We conclude that further research is needed to understand the evolution of placentation among viviparous mammals, particularly concerning the level of placental invasiveness, hormonal control and genetic underpinnings of pregnancy in marsupial taxa.


Author(s):  
Jocelyn M Cuthbert ◽  
Stewart J Russell ◽  
Irina A Polejaeva ◽  
Qinggang Meng ◽  
Kenneth L White ◽  
...  

Abstract Production of embryos with high developmental competence by somatic cell nuclear transfer (scNT) is far less efficient than for in vitro fertilized (IVF) embryos, likely due to an accumulation of errors in genome reprogramming that results in aberrant expression of RNA transcripts, including messenger RNAs (mRNA) and, possibly, microRNAs (miRNA). Thus, our objectives were to use RNAseq to determine the dynamics of mRNA expression in early developing scNT and IVF embryos in the context of the maternal-to-embryonic transition (MET) and to correlate apparent transcriptional dysregulation in cloned embryos with miRNA expression profiles. Comparisons between scNT and IVF embryos indicated large scale transcriptome differences, which were most evident at the 8-cell and morula stages for genes associated with biological functions critical for the MET. For two miRNAs previously identified as differentially expressed in scNT morulae, miR-34a and miR-345, negative correlations with some predicted mRNA targets were apparent, though not widespread among the majority of predicted targets. Moreover, although large-scale aberrations in expression of mRNAs were evident during the MET in cattle scNT embryos, these changes were not consistently correlated with aberrations in miRNA expression at the same developmental stage, suggesting that other mechanisms controlling gene expression may be involved.


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