Histology confirms that macroscopic evaluation of ovaries is a valid method for the assessment of the reproductive status in wild boar

Bovine FRAS1: mRNA Expression Profile, Genetic Variations, and Significant Correlations with Ovarian Morphological Traits, Mature Follicle, and Corpus Luteum

The amelioration of bovine fertility caused by a multi-factorial problem has always been a hot topic, among which the detection of available target genes is the most crucial. It was hypothesized that the Fraser extracellular matrix complex subunit 1 (FRAS1) gene detected by GWAS is involved in physiological activities such as ovarian development. Herein, unilateral ovaries from 2111 cows were used to examine the mRNA expression profile and polymorphisms of bovine FRAS1 and their associations with fertility-related characteristics. Firstly, it was confirmed that FRAS1 gene transcripts are expressed in various bovine tissues. Then, among five potential insertion-deletion (indel) loci, the 20 bp (named P3-D20-bp) and 15 bp (P4-D15-bp) deletion mutations were confirmed to be polymorphic with linkage equilibrium. Secondly, the P3-D20-bp polymorphism was significantly associated with ovarian weight and corpus luteum diameter in the metaestrus phase and ovarian length in the dioestrum stage. Additionally, both ovarian length and mature follicle diameter in metaestrus are significantly correlated with different genotypes of P4-D15-bp. Thirdly, the transcriptional expression of the FRAS1 gene in groups with a minimum value of ovarian weight or volume was significantly higher than the expression in groups with a maximum value. Instead of that, the more corpus luteum and mature follicles there are, the higher the transcription expression of the FRAS1 gene is. Furthermore, FRAS1 expression in cows with a heterozygous genotype (ID) of P3-D20-bp was significantly higher than others. Eventually, P3-D20-bp deletion could disturb the binding efficiency of WT1-I and Sox2 to FRAS1 sequence according to binding prediction, indicating that mutation may affect gene expression and traits by influencing the binding of transcription factors. Overall, the polymorphisms of P3-D20-bp and P4-D15-bp of the bovine FRAS1 gene significantly correlated to follicle or ovarian traits that could be applied in optimizing female fertility in cow MAS breeding programs.

Quantitative analysis of ovarian surface photographs as a tool for assessment of chemical effects on folliculogenesis and ovulation in rats

Female reproductive toxicity assessments rely on histological evaluation of ovaries by hematoxylin & eosin (H&E)-stained cross-sections. This is time-consuming, labor-intensive and costly, thus alternative methods for ovarian toxicity assessment could be valuable. Here, we report on an improved method based on quantification of antral follicles (AF) and corpora lutea (CL) using ovarian surface photographs, called 'surface photo counting' (SPC). To validate a potential utility for the method to detect effects on folliculogenesis in toxicity studies, we investigated ovaries from rats exposed to two well-known endocrine disrupting chemicals (EDCs), diethylstilbestrol (DES) and ketoconazole (KTZ). Animals were exposed to DES (0.003, 0.012, 0.048 mg/kg body weight (bw)/day) or KTZ (3, 12, 48 mg/kg bw/day) during puberty or adulthood. At the end of the exposure, ovaries were photographed under stereomicroscope and subsequently processed for histological assessments to allow for direct comparison between the two methods by quantifying AF and CL. There was a significant correlation between the SPC and histology methods, albeit CL counts correlated better than AF counts, potentially due to their larger size. Effects of DES and KTZ were found by both methods, suggesting applicability of the SPC method to chemical hazard and risk assessment. Based on our study, we propose that SPC can be employed as a fast and cheap tool for assessment of ovarian toxicity in in vivo studies to prioritize chemical exposure groups for further histological assessment.

Heavy Youngsters-Habitat and Climate Factors Lead to a Significant Increase in Body Weight of Wild Boar Females

As one of the most abundant game species in Europe, European wild boar (Sus scrofa) populations prove highly adaptable to cultivated landscapes. The ongoing process of climate change and the high agricultural yields seem to further optimize the living conditions for this species. In long-term reproduction monitoring, we collected data on the body weight of wild boar females. Over an 18-year period, the body weight of wild boar females increased continuously, then stopped and decreased. It was possible to detect differences between the body weights of animals from forest and agricultural areas. For these areas, differences in body weight development also led to a significant distinction in the onset of puberty. We conclude that, even in a highly cultivated landscape, forested areas provide habitat characteristics that may strongly influence reproduction. Second, with dominant agricultural areas in Germany, wild boar reproduction has been favored in recent decades.

An Approach for Investigating Sexual Maturity in Wild Boar Males: Testosterone and 17β-Estradiol Analysis

Simple Summary

Wild boar numbers have increased constantly over the last three decades, as have their related conflicts with modern society. For this reason, wild boars have become a frequent topic of discussion. This article describes and explains the concentrations of the two main sexual steroids, testosterone and estradiol, as well as our effort to define threshold levels to recognize the sexual maturation of wild boar males and differentiate between immature and adult boars. With the help of additional analyses on spermatozoa and morphological data, it was shown that prepubertal boars at 8 months of age could be clearly differentiated from postpubertal boars, showing significantly lower concentrations of hormones. Wild boar males older than 11 months of age, in contrast, presented hormonal values like adults. Before the completion of their first year, wild boars are physiologically able to reproduce and may take part in reproduction. The high hormonal concentrations at the end of the breeding season suggest that the mating period could last longer than usually supposed, shifting farrowing into the summer.

Abstract

Analyses of sexual steroid hormones in wild boars are rarely described. Testosterone (T) and 17β-estradiol (E2) concentrations are useful to recognize sexual maturation. As threshold values for this species are unknown, additional parameters are required. A total of 127 blood samples from wild boar males were collected to measure T and E2. Age and weight were recorded. Thirty-one epididymides were sampled too. Males were sorted into pre-and postpubertal groups based on the absence/presence of spermatozoa in epididymides and on morphological data following previous results. Forty-four males were prepubertal: the mean age and weight were 10 months and 23 kg, respectively. They showed no spermatozoa. The mean concentrations of T and E2 were 1.2 ± 1.2 ng/mL and 39.7 ± 120.3 pg/mL, respectively. Sixty-six males were postpubertal, twenty-nine of which presented spermatozoa. Their mean concentration of T was 7.6 ± 6.3 ng/mL and E2 was 664.3 ± 250.4 pg/mL. Seventeen samples could not be defined; the hormone concentrations between the two groups suggested a transitional phase consistent with puberty. Wild boars before 12 months of age had high hormone levels like older boars, indicating that they could attempt to reproduce. Hormones at the end of the mating season (January) were high so that reproduction could occur thereafter, shifting farrowing from spring to summer.

Genome-Wide Selection Sweep between Wild and Local Pigs from Europe for the Investigation of the Hereditary Characteristics of Domestication in Sus Scrofa

The phenotypic characteristics of existing domestic pigs (DPs) greatly differ from those of wild boar (WB) populations thousands of years ago. After thousands of years of human domestication, WB and DP have diverged greatly in terms of genetics. Theoretically, worldwide local pigs have independent contributions from their local WBs at the beginning of Sus scrofa domestication. The investigation of the vicissitude of the heredity material between domestic populations and their wild ancestors will help in further understanding the domestication history of domestic animals. In the present study, we performed a genome-wide association scan (GWSA) and phylogeny estimation with a total of 1098 public European Illumina 60K single nucleotide polymorphism data, which included 650 local DPs and 448 WBs. The results revealed that the phylogenetic relationship of WBs corresponds to their geographical distribution and carries large divergence with DPs, and all WB breeds (e.g., HRWB, SBWB, and TIWB) presents a closely linkage with the middle WB (e.g., HRWB, and PLWB). In addition, 64 selected candidate genes (e.g., IDH2, PIP5K1B, SMARCA2, KIF5C, and TJP2) were identified from GWSA. A total of 63 known multiple biological functional pathways were annotated by 22 genes, and ubiquinone and other terpenoid-quinone biosynthesis pathways that belong to the metabolism of cofactors and vitamins were significantly enriched (p < 0.05). The most frequent (28.57%) pathways were classified under metabolism. We confirmed that the middle European WB has made an important genetic contribution to the entire European WB populations. A series of selected genes discovered from this study provides the scientific community with a deeper understanding of the heredity performance of metabolism and emotion and the real purpose behind domestication.

High Expression of miR-204 in Chicken Atrophic Ovaries Promotes Granulosa Cell Apoptosis and Inhibits Autophagy

Chicken atrophic ovaries have decreased volume and are indicative of ovarian failure, presence of a tumor, or interrupted ovarian blood supply. Ovarian tumor is accompanied by an increase in follicular atresia, granulosa cell (GC) apoptosis, and autophagy. In a previous study, we found using high throughput sequencing that miR-204 is highly expressed in chicken atrophic ovaries. Thus, in the present study, we further investigated its function in GC apoptosis and autophagy. We found that overexpression of miR-204 reduced mRNA and protein levels of proliferation-related genes and increased apoptosis-related genes. Cell counting kit-8 (CCK-8), 5-ethynyl-2-deoxyuridine (EdU), and flow cytometry assays revealed that miR-204 inhibited GC proliferation and promoted apoptosis. Furthermore, we confirmed with reporter gene assays that Forkhead box K2 (FOXK2) was directly targeted by miR-204. FOXK2, as a downstream regulator of phosphoinositide 3-kinase (PI3K)/AKT/mammalian target of rapamycin (mTOR) signal pathways, promoted GC proliferation and inhibited apoptosis. Subsequently, we observed that miR-204 was involved in GC autophagy by targeting Transient Receptor Potential Melastatin 3 (TRPM3). The luciferase activities of the two binding sites of TRPM3 were decreased in response to treatment with a miR-204 mimic, and the autophagic flux was increased after miR-204 inhibition. However, overexpression of miR-204 had opposite results in autophagosomes and autolysosomes. miR-204 inhibits GC autophagy by suppressing the protein expression of TRPM3/AMP-activated protein kinase (AMPK)/ULK signaling pathway components. Inhibition of miR-204 enhanced autophagy by accumulating and degrading the protein levels of LC3-II (Microtubule Associated Protein Light Chain 3B) and p62 (Protein of 62 kDa), respectively, whereas miR-204 overexpression was associated with contrary results. Immunofluorescence staining showed that there was a significant reduction in the fluorescent intensity of LC3B, whereas p62 protein was increased after TRPM3 silencing. Collectively, our results indicate that miR-204 is highly expressed in chicken atrophic ovaries, which promotes GC apoptosis via repressing FOXK2 through the PI3K/AKT/mTOR pathway and inhibits autophagy by impeding the TRPM3/AMPK/ULK pathway.

Evaluation of gonadal macroscopic and microscopic morphometry reveals precocious puberty in Bísaro pig

Bísaro pig (BP), like many other local breeds reared in extensive non-industrial systems, faces many constraints to comply with the EU welfare regulation, particularly regarding the restrictions to surgical castration. In order to adapt an immunocastration protocol to overtake this issue, a puberty timeline is needed. Using gonadal morphometry data from 91 young male BP, this study intended to characterize testicular development, describing the prominent cell types and structures, to ultimately assess the age at puberty in male BP through a mixed prediction model. As expected, the relations between several macro and microscopic parameters and their relation with age were as described within the literature. Post-pubertal animals have larger and heavier gonads, lower Sertoli cell density/tubule, higher Leydig cell density and larger seminiferous tubules. Meiosis was firstly seen in 44-day-old animals, elongated spermatids in 70-day-old animals. Complete spermatogenesis was firstly identified in a 90-day-old animal. Spermatozoa were present in the epididymis of 23 animals, aged from 70 to 240 days old, and in the vas deferens of 14 animals (105 to 240 days old). The prediction model inferred that male Bísaro pigs reach puberty between 14 and 17 weeks (3 and 4 months old) and become sexually capable from 15 to 19 weeks (3.5 and 4.4 months old). These parameters confirm the sexual precocity of this breed.