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Abstract

During fertilization, avian sperm preferentially penetrate into the perivitelline membrane that covers the germinal disk region where the female nucleus is present. This phenomenon has been observed not only in domestic birds but also in wild birds; however, the mechanisms controlling sperm preference are still unclear. In this study, we investigated the possible involvement of annexin family protein in sperm–egg interaction in Japanese quail. Microscopic examination of fertilized eggs indicated that quail sperm penetration only occurred in the germinal disk region, and sperm localized outside the germinal disk were trapped in the perivitelline membrane. Western blot analysis and immunofluorescence microscopy revealed the presence of annexin A1 and A6 in the oocyte membrane, while annexin A6 localized in the perivitelline space of the germinal disk region. Further, our sperm binding assay using recombinant annexin A6 demonstrated that ejaculated sperm specifically bound to annexin A6 expressed in mammalian cell lines. These results suggest that annexin A6, which is expressed on the surface of oocytes, may function in sperm–egg interaction in the germinal disk region and that this binding may ensure sperm retention on the surface of the egg plasma membrane until fertilization takes place in Japanese quail.

Lay summary

In bird species, fertilization takes place immediately after ovulation of the egg. Sperm preferentially penetrate a specific area of the egg coating that covers the ‘germinal disk region’ – this area contains the cell that needs to be fertilized by a sperm. However, since the bird egg is extremely large in size and sperm must reach the ‘germinal disk region’ to achieve fertilization, it is unclear how this happens. Annexin proteins support fertilization in mammals, and we found that annexin A6 protein exhibits a unique localization in the germinal disk region in the eggs of Japanese quail. To test this interaction, we incubated quail sperm with cells that produced annexin A6 and found that ejaculated sperm bound to the cells. These results suggest that annexin A6 may have a role in the sperm–egg interaction in the germinal disk region in Japanese quail.

Lay summary

Compared to traditional chemotherapy agents, anti-cancer therapies are thought to be highly effective at targeting cancer cells but sparing normal cells, resulting in reduced drug side effects. However, many of processes within the cells that these drugs affect are also important for the ovary to work normally, so suppressing them in this way could have long-lasting implications for female fertility. This review examines the potential toxicity of anti-cancer therapies on the ovary.

Lay summary

Problems in ovary function lead to reduced fertility or infertility. One such condition is premature ovarian insufficiency (POI) which affects 1% of women under 40 years of age, and in over 70% of these, the cause of POI is unknown. To investigate POI, we have developed a mouse model. These mice are initially fertile but develop POI by 3 months of age. In this study, we investigated the changes in genes activated in the ovaries during the transition from fertility to POI, and we did this by comparing them to normal mice; gene activation leads to molecule production. A molecule known as cathepsin K seems to trigger changes during the onset of POI, followed by others related to structure and immune response pathways. In addition, some genes were identified that are similar between the POI mice and POI women.

Lay summary

The world is undergoing its sixth mass extinction; however, unlike previous events, the latest is caused by human activities and is resulting in the largest loss of biodiversity (all living things on Earth) for 65 million years. With an extinction rate 1000–10,000-fold greater than natural, this catastrophic decline in biodiversity is threatening our own survival. As the number of individuals within a species declines, genetic diversity reduces, threatening their long-term existence. In this review, the authors summarise approaches to indefinitely preserve living cells and tissues at low temperatures (cryobanking) and the technologies required to resurrect biodiversity. In the future when appropriate techniques become available, these living samples can be thawed and used to reinstate genetic diversity and produce live young ones of endangered species, enabling their long-term survival. The successes and challenges of genome resource cryopreservation are discussed to enable a move towards a future of stable biodiversity.

Lay summary

Endometriosis is a benign disease that can cause pain and infertility in women. Debate exists over how endometriosis should best be diagnosed. On one hand, endometriosis can be diagnosed by directly examining pelvic anatomy via a surgical procedure known as diagnostic laparoscopy. On the other hand, the disease can be diagnosed via non-surgical means such as using medical imaging, the symptoms described by the patient and whether the patient responds to non-surgical therapies such as medication. In this debate article, we argue in favour of diagnostic laparoscopy. We review the safety of the procedure, compare the ability of diagnostic laparoscopy vs medical imaging to detect endometriosis and consider the benefits of formally diagnosing or ruling out the condition.

Lay summary

Concern about fertility impairment after vaccination is one of the reasons for vaccine hesitancy in the population. This study is aimed at understanding the impact of non-mRNA COVID-19 vaccination on ejaculate quality in 53 patients undergoing semen analysis who received Covishield™ (ChAdOx1 nCoV-19 corona virus vaccine, recombinant) vaccine. No significant variation in the semen characteristics was observed between the baseline and follow-up samples in the vaccinated subjects. Results from this study affirm that Covishield™ vaccination is not detrimental to male fertility.

Abstract

Di-2-ethylhexyl phthalate (DEHP) is an extensively used plasticizer which has raised some concerns about its safety on human health. This study aimed at evaluating the effects of vanillic acid (VA) and vitamin C (VC) supplementation on DEHP-induced testicular toxicity. Thirty-five adult male Wistar rats were randomly divided into 7 groups (A–G) (n = 5) receiving distilled water; 250 mg/kg bw of DEHP only; 30 mg/kg bw of VA and 250 mg/kg bw of DEHP; 30 mg/kg bw of VC and 250 mg/kg bw of DEHP; 30 mg/kg bw of DEHP plus 30 mg/kg bw of VA and 30 mg/kg bw of VC; 30 mg/kg bw of VA only; and 30 mg/kg bw of VC only, respectively. At the end of the experiment, blood was taken from the heart via cardiac puncture and stored, semen was collected from the caudal epididymis for immediate sperm analysis, while the testes were excised and preserved for histological examination and biochemical analysis. The results showed a significant decrease (P < 0.05) in body weights, sperm motility, sperm volume, sperm viability and count, antioxidant levels, and reproductive hormonal levels, with a significant increase (P < 0.05) in sperm morphological defect and lipid peroxidation level in DEHP-only group compared with the control but was ameliorated after VA and VC administration compared to the DEHP-only treated animals. VA and VC supplementation attenuated the toxic effects of DEHP on the testicular functions, morphology, and semen characterization of the experimental adult male Wistar rats.

Lay summary

Male infertility is considered when identifiable female causes of infertility are excluded and semen quantity and quality fail to fulfil World Health Organization criteria. From conception through to adulthood, people are exposed to limitless environmental toxicants among which di-2-ethylhexyl phthalate (DEHP) commonly found in personal care products, cosmetics, and medical devices is prevalent. The present study elaborated on the importance of taking antioxidant-rich foods containing vitamin C and vanillic acid, such as those found in various fruits, olives, whole wheat, and cereal grains, in combating infertility caused by environmental toxicants. An experiment was carried out on rats to see the effect of vanillic acid and vitamin C supplementation on preventing DEHP-induced testicular toxicity. The testicles and semen were analyzed from five rats in each treated and control groups. The data led us to conclude that vanillic acid and vitamin C supplementation do have attenuating effects on DEHP-induced testicular toxicity, due to their high antioxidant and anti-inflammatory properties.

Ad libitum

feeding in broiler breeder (BB) hens causes reduced egg production, lower fertility, and improper eggshell deposition. Restricted feeding (RF) is the only effective intervention available to normalize ovarian function and improve reproductive efficiency. This study aimed to assess the transcriptional changes in ovarian cortex of BB hens with free access to feed compared to those on a RF diet. RNA was isolated from the ovarian cortex of Cobb 500 pullets raised to 10 and 16 weeks of age on either a full-feeding (FF) or RF diet. Microarray analysis identified 386 differentially expressed genes between the two feeding groups at 16 weeks of age. Gene ontology enrichment identified overrepresentation of Neuroactive ligand–receptor interaction pathways, Cell adhesion molecules, Steroid hormone biosynthesis, and various KEGG pathways. From these groups, 46 genes were selected for follow-up validation by quantitative PCR. The findings show that 33 of the 46 genes had significantly different abundance by age and/or feeding level. Most of these genes were repressed in RF hens and belonged to the steroid biosynthesis and neuropeptide signaling groups. The VIPR2 receptor was higher in the FF group leading us to hypothesize that vasoactive intestinal peptide (VIP) is an important regulator of small cortical follicles. Culture of hen cortical follicles with VIP increased Star, an indication of increased steroidogenic activity, although did not elevate Cyp11a1. These results offer insights and suggest the possible mechanisms and pathways responsible for the increases in cortical follicle growth associated with excess feed intake in BB hens.

Lay summary

Giving breeder hens unrestricted access to feed can lead to problems with their ovaries, including excessive growth of the ovary and reduced fertility. Giving a limited amount of feed is the only effective way to reduce this growth of the ovaries and improve fertility. This study aimed to assess the changes in the molecules that make proteins in the body in hens fed unrestricted and restricted diets. In the hens fed a limited amount of feed, there were more of one type of molecules, while there were more of another type in the ovaries of hens with unrestricted access to feed. These results show that how much a hen eats can alter the number of these molecules in the ovary and this could help us understand why their ovaries grow excessively and why their eggs are less fertile.

Lay summary

Endometriosis, defined as the presence of endometrium-like tissue located outside the womb, is a gynaecologic disease that affects many women. They experience severe pain, making it difficult for them to go to school or work. Medication or surgery is often not enough to relieve their pain. Therefore, these women look for ways to suppress their pain by changing their way of life. Changing their diet is an option that is often chosen by women with endometriosis. Many women experience that changing their diet helps to suppress pain symptoms. But it is not clear why changing the diet is effective. Processes in the body could be changed by taking or avoiding specific nutrients, but the effect could also be caused by the empowerment that women experience by adhering to a diet. If we want to learn more about the effect of diet on endometriosis, we have to pay attention to the following issues: first, it is important to exactly define the goal of a new study. Secondly, we have to realize that there is a difference between the study of the effect of diet on the risk of developing endometriosis and the effect of diet on endometriosis that has already developed. Thirdly, we have to realize that it can be difficult to define what the diet contains and how a control group should be defined. Fourthly, it is important to define factors that make it difficult to adhere to a diet. Fifthly, we need to try to understand what happens in the body that may cause the effect of a diet in endometriosis. In this opinion paper, these issues will be addressed.

Lay summary

Embryo transfer is the most emotional part for patients during in vitro fertilization treatment. Over the last decade, the embryo transfer procedure has undergone numerous changes in the guidelines in order to increase pregnancy rates. One such procedure is the loading of the embryo into the catheter, a thin tube that helps us transfer embryo into the uterine cavity. Very few research studies looked closely at embryo-loading technique per se. Furthermore, different infertility laboratories use various techniques to load embryo. The aim of our study was to compare the two most popular embryo-loading techniques. In 249 women, we transferred embryo aspirated into the catheter with small droplets of air, and in the group of 244 patients, we filled catheter only with fluid. Our main outcome measured was the clinical pregnancy rate. Based on our results, we did not find that embryo-loading technique affected patient’s chances of achieving pregnancy.