Influence of outer membrane vesicles of Proteus mirabilis isolated from boar semen on sperm function

Exosomes from porcine serum as endogenous additive maintain function of boar sperm during liquid preservation at 17 °C in vitro

The supplementation of sperm culture media with serum is quite common, and improves both sperm survival and motility. However, the link between serum and sperm remains poorly understood. The present study is the first investigation of the effects on sperm quality and function of endogenous porcine serum exosomes in medium used for culturing boar sperm. Scanning electron microscopy (SEM) confirmed that serum-derived exosomes from both castrated boars (cbsExos) and sows (ssExos) exhibited typical nanostructural morphology and expressed CD63, CD9, and Alix, as shown by Western blotting. At 17 °C, the progressive motility and membrane integrity of sperm were significantly increased after incubation of fresh boar semen for 7 days with cbsExos-4 (8 × 1010 particles/mL) or ssExos-16 (32 × 1010 particles/mL). Moreover, cbsExos-4 and ssExos-16 were found to be effective sperm additives, improving mitochondrial transmembrane potential (ΔΨm) and adenosine triphosphate (ATP) content, total antioxidant activity (T-AOC), superoxide dismutase (SOD) activity, and glutathione peroxidase (GPx) activity while reducing reactive oxygen species (ROS) levels, and malondialdehyde (MDA) content following preservation at 17 °C after a 5-day incubation. Both fluorescence and SEM showed that the serum exosomes bound directly to the sperm membrane, suggesting an interaction that could influence sperm-zona pellucida binding. Overall, this study provides new insights into the potential benefits of adding cbsExos and ssExos to enhance the quality of boar sperm during ambient temperature preservation, which may lead to advancements in sperm preservation strategies.

The multidrug-resistant Pseudomonas fluorescens strain: a hidden threat in boar semen preservation

Although the bacterial composition of boar ejaculate has been extensively studied, the bacterial composition of extended boar semen is often overlooked, despite the potential risks these microorganisms may pose to the long-term preservation of extended boar semen at 15-17°C. In this study, we characterized the bacterial community composition of extended semen and discovered that Pseudomonas spp. was the dominant flora. The dominant strains were further isolated and identified as a potential new species in the Pseudomonas fluorescens group and named GXZC strain, which had adverse effects on sperm quality and was better adapted to growth at 17°C. Antimicrobial susceptibility testing showed that the GXZC strain was resistant to all commonly used veterinary antibiotics. Whole-genome sequencing (WGS) and genome annotation revealed the large genetic structure and function [7,253,751 base pairs and 6,790 coding sequences (CDSs)]. Comparative genomic analysis with the closest type strains showed that the GXZC strain predicted more diversity of intrinsic and acquired resistance genes to multi-antimicrobial agents. Taken together, our study highlights a problem associated with the long-term storage of extended boar semen caused by a P. fluorescens group strain with unique biological characteristics. It is essential to develop a new antibacterial solution for the long-term preservation of boar semen.

Virulence-related factors and antimicrobial resistance in Proteus mirabilis isolated from domestic and stray dogs

Introduction

Proteus mirabilis is a multi-host pathogen that causes diseases of varying severity in a wide range of mammals, including humans. Proteus mirabilis is resistant to multiple antibiotics and has acquired the ability to produce expanded spectrum of β-lactamases, leading to serious public health problems. However, the available information on P. mirabilis isolated from feces of dogs, is still poorly understood, as is the correlation between its virulence-associated genes (VAGs) and antibiotic resistance genes (ARGs).

Method

In this study, we isolated 75 strains of P. mirabilis from 241 samples, and investigated the swarming motility, biofilm formation, antimicrobial resistance (AMR), distribution of VAGs and ARGs, as well as the presence of class 1, 2, and 3 integrons in these isolates.

Results

Our findings suggest a high prevalence of intensive swarming motility and strong biofilm formation ability among P. mirabilis isolates. Isolates were primarily resistant to cefazolin (70.67%) and imipenem (70.67%). These isolates were found to carry ureC, FliL, ireA, zapA, ptA, hpmA, hpmB, pmfA, rsbA, mrpA, and ucaA with varying prevalence levels of 100.00, 100.00, 100.00, 98.67, 98.67, 90.67, 90.67, 90.67, 90.67, 89.33, and 70.67%, respectively. Additionally, the isolates were found to carry aac(6')-Ib, qnrD, floR, bla_CTX-M, bla_CTX-M-2, bla_OXA-1, bla_TEM, tetA, tetB and tetM with varying prevalence levels of 38.67, 32.00, 25.33, 17.33, 16.00, 10.67, 5.33, 2.67, 1.33, and 1.33%, respectively. Among 40 MDR strains, 14 (35.00%) were found to carry class 1 integrons, 12 (30.00%) strains carried class 2 integrons, while no class 3 integrons was detected. There was a significant positive correlation between the class 1 integrons and three ARGs: bla_TEM, bla_CTX-M, and bla_CTX-M-2. This study revealed that P. mirabilis strains isolated from domestic dogs exhibited a higher prevalence of MDR, and carried fewer VAGs but more ARGs compared to those isolated from stay dogs. Furthermore, a negative correlation was observed between VAGs and ARGs.

Discussion

Given the increasing antimicrobial resistance of P. mirabilis, veterinarians should adopt a prudent approach towards antibiotics administration in dogs to mitigate the emergence and dissemination of MDR strains that pose a potential threat to public health.

Comparative assessment of reproductive capacity of boar-sires depending on the breed and season

The article highlights the results of the reproductive capacity of different breeds of boar sires in the farms of eastern, southern, and central regions of Ukraine in dynamics over three years are given. It represented the influence of the year's season on sperm quality by estimating the ejaculate volume, concentration, and motility of sperm of boars-sires of the different breeds and their hybrids. Data were also calculated on the culling of ejaculates of boar sires of various breeds for the years 2019–2021 in the dynamics. In a comparative aspect, the indicators were analyzed by the following genotypes: Large White, Ukrainian Meat, Landrace, Duroc, Yorkshire, and synthetic line Makster. The reproductive capacity of boars was within the limits of the indicators for the elite and first classes. However, specific differences were observed between boars of different breeds, which were constant and took place during the three studied years. The difference in the concentration of sperm in the ejaculates of the Ukrainian Meat breed gradually decreased starting from 2019 and was the smallest in 2021. The highest ejaculate volume was found in boars of the Ukrainian meat breed (310.9 ± 113.2 cm3), and the sperm concentration was the highest in boar sires of the Large White breed (215.7 ± 83.5 million/cm3). On the other side, hybrids of the Large White breed had low indicators compared to other groups of animals (Large White × Yorkshire – 184.2 ± 68.5 million/cm3, Large White × Makster – 189.0 ± 59.7 million/cm3). Sperm motility did not undergo significant breed differences: the average annual indicator of motility was 7.6 ± 0.09 points, and it was the highest in the winter period (8.6 ± 0.11 points), however, for the established variances; the dilution was used 1.65–3.58 times and a high percentage of unusable sperm (15.4–29.4 % of the total amount) was established in a large number of samples. According to the results of the annual analysis of the sperm production of boars, a high degree of culling of ejaculates was established for various reasons (high level of sperm agglutination (52.3–74.0 %), low concentration of germ cells (14.5–29.8 %), presence of foreign impurities (5,8–12.4 %). The highest percentage of culling was in summer (20.3 %). Thus, the obtained results showed the breed and seasonal characteristics of the reproductive capacity of breeding boars.

Bacteria and Boar Semen Storage: Progress and Challenges

Porcine breeding today is based on artificial insemination with chilled semen. This is stored at 5 °C with antibiotic supplementation to avoid bacteriospermia. There are many negative consequences on sperm quality and functionality as a result of bacterial contamination, as well as on the health of the sow. Nowadays, various techniques are being developed to reduce the indiscriminate use of antibiotics and thus avoid the generation of antibiotic resistance genes. This review aims to inform about the bacterial contamination consequences of storing liquid semen from boar and to provide an update on current methods and alternatives to antibiotic use in cold storage.

Impact of Escherichia coli Outer Membrane Vesicles on Sperm Function

Reproductive tract infections account for approximately 15% of male infertility cases. Escherichia coli (E. coli) represents the most frequently isolated bacterial strain in the semen of infertile men. All Gram-negative bacteria constitutively produce outer membrane vesicles (OMVs). The present study proved, for the first time, the involvement of OMVs in human sperm function. E. coli OMVs were isolated by ultracentrifugation and characterized via sodium dodecyl sulfate–polyacrylamide gel electrophoresis (SDS-PAGE), transmission electron microscopy (TEM) and dynamic light scattering (DLS) analysis. Human sperm was exposed to OMVs (8 µg/mL) for different times (30, 45, 60 and 90 min). The vitality, motility, morphology, ROS level and DNA fragmentation of spermatozoa were evaluated. OMVs reduced the progressive motility and increased the immobile spermatozoa amount after 30 min of treatment. In addition, a significant increase in the percentage of intracellular ROS and sperm DNA fragmentation was recorded for each vesicular exposure time. These preliminary findings prove that OMVs contribute to altering human sperm function via two mechanisms: (i) impaired motility and (ii) DNA fragmentation.

Role of Outer Membrane Vesicles From Helicobacter pylori in Atherosclerosis

Infection is thought to be involved in the pathogenesis of atherosclerosis. Studies have shown the association between helicobacter pylori (H. pylori) and coronary artery disease. It is interesting to find H. pylori DNA and cytotoxin-associated gene A (CagA) protein in atherosclerotic plaque. Outer membrane vesicles (OMVs), secreted by H. pylori, exert effects in the distant organ or tissue. However, whether or not OMVs from H. pylori are involved in the pathogenesis of atherosclerosis remains unknown. Our present study found that treatment with OMVs from CagA-positive H. pylori accelerated atherosclerosis plaque formation in ApoE^–/– mice. H. pylori-derived OMVs inhibited proliferation and promoted apoptosis of human umbilical vein endothelial cells (HUVECs), which was also reflected in in vivo studies. These effects were normalized to some degree after treatment with lipopolysaccharide (LPS)-depleted CagA-positive OMVs or CagA-negative OMVs. Treatment with H. pylori-derived OMVs increased reactive oxygen species (ROS) levels and enhanced the activation of nuclear factor-κB (NF-κB) in HUVECs, which were reversed to some degree in the presence of a superoxide dismutase mimetic TEMPOL and a NF-κB inhibitor BAY11-7082. Expressions of interleukin-6 (IL-6) and tumor necrosis factor alpha (TNF-α), two inflammatory factors, were augmented after treatment with OMVs from H. pylori. These suggest that H. pylori-derived OMVs accelerate atherosclerosis plaque formation via endothelium injury. CagA and LPS from H. pylori-OMVs, at least in part, participate in these processes, which may be involved with the activation of ROS/NF-κB signaling pathway. These may provide a novel strategy to reduce the incidence and development of atherosclerosis.

Impact of Oxidative Stress on Male Reproduction in Domestic and Wild Animals

Oxidative stress occurs when the levels of reactive oxygen species (ROS) overcome the antioxidant defenses of the organism, jeopardizing several biological functions, including reproduction. In the male reproductive system, oxidative stress not only impairs sperm fertility but also compromises offspring health and survival, inducing oxidative damage to lipids, proteins and nucleic acids. Although a clear link between oxidative stress and male fertility disorders has been demonstrated in humans and laboratory rodents, little information is available about the implications of impaired redox homeostasis in the male fertility of domestic and wild animals. Therefore, this review aims to provide an update regarding the intrinsic and extrinsic factors that are associated with oxidative stress in the male reproductive system and their impact on the reproductive performance of domestic and wild animals. The most recent strategies for palliating the detrimental effects of oxidative stress on male fertility are reviewed together with their potential economic and ecological implications in the livestock industry and biodiversity conservation.

Chlorpyrifos inhibits sperm maturation and induces a decrease in mouse male fertility

BACKGROUND

Pesticides, especially organophosphorus pesticides such as chlorpyrifos (CPF), play an important role in modern agriculture. Studies have shown that pesticide residues are an important cause of male reproductive injury in mammal.

AIM

The aim of this study was to evaluate the reproductive damage caused by CPF in male mice and investigate the underlying mechanisms.

METHODS

In vivo, C57BL/6 mice (6-8 weeks old) were treated with CPF for 14, 70, and 80 days by intraperitoneal injection, intragastric administration, and dietary supplementation, respectively. Then, sperm from the cauda epididymidis was cultured in vitro to confirm the deleterious effects of CPF.

RESULTS

The in vivo results indicated that, after treatment with CPF by dietary supplementation and intraperitoneal injection, the expression of reproduction-related genes in the mouse testes was altered, although the mice were fertile and the testes presented no morphological abnormalities. Notably, mating experiments revealed that the fertility of male mice was decreased following CPF administration by gavage. Sperm motility within the cauda epididymidis declined significantly after CPF treatment, which was accompanied by a decrease in sperm density, upregulation of relative reactive oxygen species (ROS) levels, and downregulation of glutathione reductase activity. In vitro incubation experiments showed that sperm rapidly lost their capacity for linear movement; the relative ROS levels also increased significantly, while the mitochondrial membrane potential (MMP) showed a significant decrease. However, the integrity of the plasma membrane was not affected by CPF administration.

CONCLUSIONS

The above data indicated that exposure to CPF reduces sperm motility by disrupting mitochondrial function and increasing the level of oxidative stress during sperm maturation, thereby reducing the fecundity of male mice.

Long-term storage of boar seminal doses contaminated with Proteus vulgaris: A dose-dependent effect on sperm motility and sperm-bacteria interaction

This study evaluated how Proteus vulgaris affects sperm quality and sperm-bacteria interaction in stored semen samples. A strain of P. vulgaris resistant to streptomycin, penicillin, lincomycin and spectinomycin was added to boar semen in doses of 10³, 10⁵, 10⁶, 10⁷ and 10⁸ CFU/mL. A sample in which there was no addition of P. vulgaris was the negative control. Sperm quality was determined by evaluating sperm motility and morphology using the computer-assisted sperm analysis (CASA) system, and plasma membrane and acrosome integrity using flow cytometry at 0, 1, 2, 4, 6, 8 and 10 days of liquid-storage at 17 °C. At the same time points, pH, sperm agglutination, sperm-bacteria interaction and bacterial growth were also assessed. There was impaired sperm motility when the infective doses of P. vulgaris were equal to or greater than 10⁵ CFU/mL with the effect being dose-dependent (P < 0.05). When infective doses of P. vulgaris were of 10⁶ to 10⁸ CFU/mL there were impairments of plasma membrane and acrosome integrity by Day 1 of storage (P < 0.05), and alkalinisation of the storing medium by Day 4 (P < 0.05). Bacterial adhesion increased when infective dose of P. vulgaris was greater and as duration of storage increased. P. vulgaris had a high affinity for the mid- and principal pieces of sperm cells. It is concluded there were alterations in sperm motility in samples infected with P. vulgaris that were associated with bacterial adhesion and medium alkalinisation.