SWI/SNF chromatin remodeling subunit Smarca4/BRG1 is essential for female fertility†

Mammalian folliculogenesis is a complex process that involves the regulation of chromatin structure for gene expression and oocyte meiotic resumption. The SWI/SNF complex is a chromatin remodeler using either Brahma-regulated gene 1 (BRG1) or BRM (encoded by Smarca4 and Smarca2, respectively) as its catalytic subunit. SMARCA4 loss of expression is associated with a rare type of ovarian cancer; however, its function during folliculogenesis remains poorly understood. In this study, we describe the phenotype of BRG1 mutant mice to better understand its role in female fertility. Although no tumor emerged from BRG1 mutant mice, conditional depletion of Brg1 in the granulosa cells (GCs) of Brg1fl/fl;Amhr2-Cre mice caused sterility, whereas conditional depletion of Brg1 in the oocytes of Brg1fl/fl;Gdf9-Cre mice resulted in subfertility. Recovery of cumulus-oocyte complexes after natural mating or superovulation showed no significant difference in the Brg1fl/fl;Amhr2-Cre mutant mice and significantly fewer oocytes in the Brg1fl/fl;Gdf9-Cre mutant mice compared with controls, which may account for the subfertility. Interestingly, the evaluation of oocyte developmental competence by in vitro culture of retrieved two-cell embryos indicated that oocytes originating from the Brg1fl/fl;Amhr2-Cre mice did not reach the blastocyst stage and had higher rates of mitotic defects, including micronuclei. Together, these results indicate that BRG1 plays an important role in female fertility by regulating granulosa and oocyte functions during follicle growth and is needed for the acquisition of oocyte developmental competence.

Metformin prevents age-associated ovarian fibrosis by modulating the immune landscape in female mice

Ovarian fibrosis is a pathological condition associated with aging and is responsible for a variety of ovarian dysfunctions. Given the known contributions of tissue fibrosis to tumorigenesis, it is anticipated that ovarian fibrosis may contribute to ovarian cancer risk. We recently reported that diabetic postmenopausal women using metformin had ovarian collagen abundance and organization that were similar to premenopausal ovaries from nondiabetic women. In this study, we investigated the effects of aging and metformin on mouse ovarian fibrosis at a single-cell level. We discovered that metformin treatment prevented age-associated ovarian fibrosis by modulating the proportion of fibroblasts, myofibroblasts, and immune cells. Senescence-associated secretory phenotype (SASP)-producing fibroblasts increased in aged ovaries, and a unique metformin-responsive subpopulation of macrophages emerged in aged mice treated with metformin. The results demonstrate that metformin can modulate specific populations of immune cells and fibroblasts to prevent age-associated ovarian fibrosis and offers a new strategy to prevent ovarian fibrosis.

Transcriptional heterogeneity of stemness phenotypes in the ovarian epithelium

The ovarian surface epithelium (OSE) is a monolayer of epithelial cells surrounding the ovary that ruptures during each ovulation to allow release of the oocyte. This wound is quickly repaired, but mechanisms promoting repair are poorly understood. The contribution of tissue-resident stem cells in the homeostasis of several epithelial tissues is widely accepted, but their involvement in OSE is unclear. We show that traits associated with stem cells can be increased following exposure to the cytokine TGFB1, overexpression of the transcription factor Snai1, or deletion of Brca1. We find that stemness is often linked to mesenchymal-associated gene expression and higher activation of ERK signalling, but is not consistently dependent on their activation. Expression profiles of these populations are extremely context specific, suggesting that stemness may not be associated with a single, distinct population, but rather is a heterogeneous cell state that may emerge from diverse environmental cues. These findings support that the OSE may not require distinct stem cells for long-term maintenance, and may instead achieve this through transient dedifferentiation into a stem-like state.

Using spheroids as a model, the authors report the molecular signatures of ovarian surface epithelial (OSE) cells exhibiting stemness phenotype under various conditions in vitro, and found that there is a large degree of heterogeneity in the transcriptional profiles of stem cells induced under different conditions. They suggest that maintenance of the OSE may not require a single stem cell population, but heterogeneous stem cells that can be induced transiently under diverse environmental cues.

The significance of ovarian fibrosis

Ovarian aging is associated with significant changes in the structural organization of collagen, resulting in ovarian fibrosis. In many other tissues, fibrosis increases risks associated with tumorigenesis and metastasis. Thus, it is possible that ovarian fibrosis increases the risk of ovarian cancer by creating a microenvironment more permissive to tumor growth. In this research perspective, we review the impact of female reproduction on the development of ovarian fibrosis and the contributions of genetic and hormonal disruptions such as BRCA mutation, polycystic ovarian syndrome, and infertility to structural changes in the ovary and their relative risk of ovarian cancer. We also explore new fundamental questions in the field of ovarian fibrosis and possible prevention strategies such as metformin.

Effect of heifer age on the granulosa cell transcriptome after ovarian stimulation

Genomic selection is accelerating genetic gain in dairy cattle. Decreasing generation time by using younger gamete donors would further accelerate breed improvement programs. Although ovarian stimulation of peripubertal animals is possible and embryos produced in vitro from the resulting oocytes are viable, developmental competence is lower than when sexually mature cows are used. The aim of the present study was to shed light on how oocyte developmental competence is acquired as a heifer ages. Ten peripubertal Bos taurus Holstein heifers underwent ovarian stimulation cycles at the ages of 8, 11 (mean 10.8) and 14 (mean 13.7) months. Collected oocytes were fertilised in vitro with spermatozoa from the same adult male. Each heifer served as its own control. The transcriptomes of granulosa cells recovered with the oocytes were analysed using microarrays. Differential expression of certain genes was measured using polymerase chain reaction. Principal component analysis of microarray data revealed that the younger the animal, the more distinctive the gene expression pattern. Using ingenuity pathway analysis (IPA) and NetworkAnalyst (www.networkanalyst.ca), the main biological functions affected in younger donors were identified. The results suggest that cell differentiation, inflammation and apoptosis signalling are less apparent in peripubertal donors. Such physiological traits have been associated with a lower basal concentration of LH.

Expression of atresia biomarkers in granulosa cells after ovarian stimulation in heifers

The use of younger gamete donors in dairy cattle genetic selection programs significantly accelerates genetic gains by decreasing the interval between generations. Ovarian stimulation (OS) and the practice of follicle-stimulating hormone (FSH) withdrawal, also known as coasting, are intensively used in pre-pubertal heifers without detrimental effects on subsequent reproductive performance but generally with lower embryo yields. However, recent data from embryo transfer programs showed similar embryo yields in younger and sexually mature animals but with a significant difference in the coasting period. The aim of the present study was to identify a set of granulosa cell biomarkers capable of distinguishing optimal follicle differentiation from late differentiation and atresia in order to assess the differences in coasting dynamics between pre- and post-pubertal donors. We integrated transcriptomic data sets from a public depository and used vote counting meta-analysis in order to elucidate the molecular changes occurring in granulosa cells during late follicle differentiation and atresia. The meta-analysis revealed the gene expression associated with follicle demise, and most importantly, identified potential biomarkers of that status in bovine granulosa cells. The comparison of the expression of six biomarkers between pre- and post-pubertal donors revealed that younger donors had more signs of atresia after the same period of coasting. We found different follicular dynamics following coasting in younger donors. It is possible that younger donors are less capable to sustain follicular survival most likely due to insufficient luteinizing hormone signaling. In summary, the pre-pubertal status influences follicular dynamics and reduces the oocyte developmental competence curve following OS and FSH withdrawal in heifers.

Steroidogenic genes expressions are repressed by high levels of leptin and the JAK/STAT signaling pathway in MA-10 Leydig cells

The adipose tissue is an important endocrine organ secreting numerous peptide hormones, including leptin. Increased circulating levels of leptin, as a result of hormonal resistance in obese individuals, may contribute to lower androgen production in obese males. However, the molecular mechanisms involved need to be better defined. Androgens are mainly produced by Leydig cells within the testis. In male rodents, activation of the leptin receptor modulates a cascade of intracellular signal transduction pathways which may lead to regulation of transcription factors having influences on steroidogenesis in Leydig cells. Thus, as a result of high leptin levels interacting with its receptor and modulating the activity of the JAK/STAT signaling pathway, the activity of transcription factors important for steroidogenic genes expressions may be inhibited in Leydig cells. Here we show that Lepr is increasingly expressed within Leydig cells according to postnatal development. Although high levels of leptin (corresponding to obesity condition) alone had no effect on Leydig cells' steroidogenic genes expression, it downregulated cAMP-dependent activations of the cholesterol transporter Star and of the rate-limiting steroidogenic enzyme Cyp11a1. Our results suggest that STAT transcriptional activity is downregulated by high levels of leptin, leading to reduced cAMP-dependent steroidogenic genes (Star and Cyp11a1) expressions in MA-10 Leydig cells. However, other transcription factors such as members of the SMAD and NFAT families may be involved and need further investigation to better define how leptin regulates their activities and their relevance for Leydig cells function.

Comparative analysis of granulosa cell gene expression in association with oocyte competence in FSH-stimulated Holstein cows

Ovarian stimulation with exogenous FSH followed by FSH withdrawal or ‘coasting’ is an effective means of increasing the number of oocytes obtainable for the in vitro production of cattle embryos. However, the quality of the oocytes thus obtained varies considerably from one cow to the next. The aim of the present study was to gain a better understanding of the follicular conditions associated with low oocyte developmental competence. Granulosa cells from 94 Holstein cows in a commercial embryo production facility were collected following ovarian stimulation and coasting. Microarray analysis showed 120 genes expressed with a differential of at least 1.5 when comparing donors of mostly competent with donors of mostly incompetent oocytes. Using ingenuity pathway analysis, we revealed the main biological functions and potential upstream regulators that distinguish donors of mostly incompetent oocytes. These are involved in cell proliferation, apoptosis, lipid metabolism, retinol availability and insulin signalling. In summary, we demonstrated that differences in follicle maturity at collection could explain differences in oocyte competence associated with individual animals. We also revealed deficiencies in lipid metabolism and retinol signalling in granulosa cells from donors of mostly incompetent oocytes.

Transcriptome meta-analysis of three follicular compartments and its correlation with ovarian follicle maturity and oocyte developmental competence in cows

Oocyte developmental competence in superstimulated cows is dependent in part on the duration of the FSH coasting. FSH coasting refers to superstimulation with FSH (2 days of endogenous FSH following follicle ablation and 3 days of FSH injections) followed by no FSH for a specific duration. The optimal duration varies among individuals. FSH coasting appears to modulate the transcriptome of different follicular compartments, which cooperate as a single functional unit. However, the integrative effects of FSH coasting on different follicular compartments remain ambiguous. Meta-analysis of three independent transcriptome studies, each focused on a single cell type (granulosa, cumulus, and oocyte) during FSH coasting, allowed the identification of 12 gene clusters with similar time-course expression patterns in all three compartments. Network analysis identified HNF4A (involved in metabolic functions) and ELAVL1 (an RNA-binding protein) as hub genes regulated respectively upward and downward in the clusters enriched at the optimal coasting time, and APP (involved in mitochondrial functions) and COPS5 (a member of the COP9 signalosome) as hub genes regulated respectively upwards and downwards in the clusters enriched progressively throughout the coasting period. We confirmed the effects on HNF4A downstream targets (TTR, PPL) and other hub genes (ELAVL1, APP, MYC, and PGR) in 30 cows with RT-quantitative PCR. The correlation of hub gene expression levels with FSH coasting indicated that a combination of these genes could predict oocyte competence with 83% sensitivity, suggesting that they are potential biomarkers of follicle differentiation. These findings could be used to optimize FSH coasting on an individual basis.

Depletion of penicillin G residues in tissues, plasma and injection sites of market pigs injected intramuscularly with procaine penicillin G

Procaine penicillin G was administered by intramuscular (i.m.) injection to groups of healthy 100 kg market pigs at the approved label dose (15,000 IU/kg body weight), once daily for three consecutive days; or an extra-label dose (66,000 IU/kg body weight), once daily for five consecutive days. Penicillin G residue depletion was followed in plasma, tissue and injection sites using a liquid chromatographic method. Groups of pigs were killed 1, 2, 3, 4, 5 and 8 days after the last injection with the label dose. Penicillin G was not detected in liver after 1 day of withdrawal, in muscle and fat after 2 days of withdrawal, in plasma after 4 days of withdrawal, in skin after 5 days of withdrawal, or in kidney and the injection sites after 8 days of withdrawal. Other groups of pigs were killed 1, 2, 3, 5 and 7 days after injection with the extra-label dose. In these pigs penicillin G was not found in liver after 2 days of withdrawal, in fat after 3 days of withdrawal, or in the muscle, skin, plasma and injection sites after 7 days of withdrawal. Penicillin G was found at all times in the kidneys of the groups of pigs that received the high dose. The technique used for neck injections was critical to obtain intramuscular rather than intermuscular injections. The Bureau of Veterinary Drugs, Health Protection Branch, Health Canada calculated that the appropriate withdrawal period for pigs was 8 days for a dose of 15,000 IU procaine penicillin G/kg body weight and 15 days for a dose of 66,000 IU/kg.

Disposition of penicillin G after administration of benzathine penicillin G, or a combination of benzathine penicillin G and procaine penicillin G in cattle

Plasma concentration of penicillin G was evaluated in beef steers after administration of either a combination of benzathine penicillin G and procaine penicillin G in a 1:1 mixture at a dosage of 9,000 U/kg of body weight, IM (n = 5), 24,000 U/kg, IM (n = 5), or 8,800 U/kg, SC (n = 5), or benzathine penicillin G alone at a dosage of 12,000 U/kg, IM (n = 7). Plasma concentration of penicillin G was measured by use of a high-performance liquid chromatography assay that had a limit of determination of 0.005 microgram/ml. At a dosage for this combination of 9,000 U/kg IM, and 8,800 U/kg, SC, which are approved label recommendations in Canada, and the United States, respectively, mean (+/- SEM) peak plasma concentration was 0.58 (+/- 0.15) and 0.44 (+/- 0.02) microgram/ml, respectively. Although plasma penicillin concentration was quantifiable for 7 days in the steers that received 9,000 U/kg, IM, and for 4 days in the steers that received 8,800 U/kg, SC, the concentration was < 0.1 microgram/ml in both groups after the first 12 hours. After administration of the combination at dosage of 24,000 U/kg, IM, there was an initial peak plasma concentration at approximately 2 hours; thereafter, plasma concentration decreased slowly, with half-life of 58 hours. Although plasma penicillin G concentration was quantifiable for 12 days at this dosage, concentration was < 0.1 microgram/ml after the first 48 hours. After the initial 48 hours, plasma concentration of penicillin was of similar magnitude and decreased at similar rate for the combination at dosage of 24,000 U/kg and for 12,000 U/kg of benzathine penicillin G alone.(ABSTRACT TRUNCATED AT 250 WORDS)

Depletion of penicillin G residues in tissues and injection sites of yearling beef steers dosed with benzathine penicillin G alone or in combination with procaine penicillin G

The contribution of benzathine penicillin G to residues in tissues and injection sites of yearling beef steers was assessed by treating seven groups of five to seven steers with either benzathine and procaine penicillin G together or benzathine penicillin G alone. Steers were injected with a commercial combination of benzathine and procaine penicillin G according to the Canadian (intramuscular) or United States (subcutaneous) label dosages of 8600 and 8800 IU penicillin G/kg body weight, respectively. They were killed 14 or 30 days after the intramuscular injections, and 30 days after the subcutaneous injections. At the label withdrawal times, Canadian 14 days and United States 30 days, the levels in the injection sites for all of the treatments were 30-60 times above the Canadian and United States' Maximum Residue Limit of 50 micrograms/kg, while liver, kidney and gluteal muscle levels were below the Maximum Residue Limit. Other steers were injected intramuscularly with 24,000 IU benzathine/procaine penicillin G/kg body weight and slaughtered 8, 14 or 50 days after injection. Fifty-day injection site residues were 24 times the Maximum Residue Limit. Another group of steers was injected intramuscularly with benzathine penicillin G alone at 12,000 IU/kg body weight and slaughtered 14 days later. Penicillin G levels in the injection sites were 156 times the Maximum Residue Limit. The persistence of penicillin G residues at the injection sites in all the treatment groups appears to be attributable primarily to benzathine penicillin G. Visual inspection of muscle surfaces did not reliably reveal all injection site lesions in the underlying musculature.

Depletion of intramuscularly and subcutaneously injected procaine penicillin G from tissues and plasma of yearling beef steers

Withdrawal periods required when doses of 24,000 IU and 66,000 IU of procaine penicillin G/kg body weight were administered to yearling beef steers by intramuscular injection daily for five consecutive days were investigated. These dosages are in excess of product label recommendations, but are in the range of procaine penicillin G dosages that have been administered for the treatment of some feedlot bacterial diseases. The approved dose in Canada is 7,500 IU/kg body weight intramuscularly, once daily, with a withdrawal period of five days. Based on the tissue residue data from this study, the appropriate withdrawal period is ten days for the 24,000 IU/kg body weight dose and 21 days for the 66,000 IU/kg body weight dose when administered intramuscularly to yearling beef steers. In a related study, 18 yearling beef steers received 66,000 IU of procaine penicillin G/kg body weight administered by subcutaneous injection, an extra-label treatment in terms of both dose and route of administration, typical of current practice in some circumstances. Deposits of the drug were visible at subcutaneous injection sites up to ten days after injection, with more inflammation and hemorrhage observed than for intramuscular injections of the same dose. These results suggest that procaine penicillin G should not be administered subcutaneously at high doses; and therefore a withdrawal period was not established for subcutaneous injection.

A study of the disposition of procaine penicillin G in feedlot steers following intramuscular and subcutaneous injection

The disposition of an aqueous suspension of procaine penicillin G (300,000 U/mL) was studied in feedlot steers. Four groups of three steers were used. Steers in groups 1 and 2 received procaine penicillin G once daily for 5 days intramuscularly (i.m.) at a dose of 24,000 U/kg (group 1) or of 66,000 U/kg (group 2). The injection on the last day was administered in the gluteal muscle. Steers in group 3 (i.m. neck injection) and group 4 [subcutaneous (s.c.) injection] each received a single dose of procaine penicillin G at a dose of 66,000 U/kg. From every animal, after the last injection in groups 1 and 2 and following the single injection in groups 3 and 4, a series of blood samples was taken at fixed time intervals. The plasma from these samples was analysed for penicillin G by a high performance liquid chromatography (HPLC) assay in order to determine the disposition of penicillin. The maximum plasma concentration (Cmax) and the area under the curve (AUC) were significantly different between groups 1 and 2, but we found no difference in the disappearance rate constant between these two groups. Group 4 single s.c. injections produced a lower mean Cmax (1.85 +/- 0.27 microgram/mL) than the mean Cmax (4.24 +/- 1.08 micrograms/mL) produced in group 3 by i.m. injections into the neck muscle or the mean Cmax (2.63 +/- 0.27 microgram/mL) produced in group 2 by i.m. injections into the gluteal muscle. However the mean Cmax produced by i.m. injections into the neck muscles (group 3) was higher than the mean Cmax produced by i.m. injections into the gluteal muscle (group 2). Additionally, the disappearance t1/2 was longer (18.08 h) in group 4 following the s.c. injection and shorter (8.85 h) in group 3 following the i.m. neck injection, than the t1/2 following administration of the same dose i.m. into the gluteal muscle (15.96 h) in group 2. In this study, when procaine penicillin G was injected into the gluteal muscle, doses of 66,000 U/kg were necessary to produce plasma concentrations that were above a minimum inhibitory concentration (MIC) for penicillin G of 1.0 microgram/mL as compared to doses of 24,000 U/kg.

In vitro germicidal activity of teat dips against Nocardia asteroides and other udder pathogens

Nine commercial teat dip formulations containing 1.94% linear dodecylbenzene sulfonic acid, or 1% available iodine from nonylphenoxypoly (ethyleneoxy) ethanol-iodine complex, or .5% chlorhexidine acetate were tested for contamination with aerobic and anaerobic bacteria and their in vitro germicidal activity against Staphylococcus aureus, Streptococcus agalactiae, Escherichia coli, and Nocardia asteroides. All products were free of bacteria when neutralized samples were tested on blood agar or liquid thioglycollate media. To test for in vitro efficacy, each teat dip preparation was mixed with a suspension of one of the pathogenic test organisms containing 10(8) bacteria/ml (final concentration) for .5 to 15 min. Viable bacteria were evaluated by direct plating of neutralized aliquots and by filtration techniques. All products were effective against E. coli, Staph. aureus, and Strep. agalactiae. With N. asteroides, the direct plating method gave equivocal results. The filtration experiments indicated that all teat dips containing dodecylbenzene sulfonic acid and nonylphenoxypoly (ethyleneoxy) ethanol-iodine complex were effective against all four pathogens. Three of the teat dips containing chlorhexidine acetate were ineffective against N. asteroides. The fourth teat dip, containing chlorhexidine acetate and an emollient, was partially effective.

Sweat sulfate concentrations are decreased in cystic fibrosis

We have developed methods to measure inorganic sulfate in small volumes of sweat, and compared sulfate concentrations in sweat samples from CF patients and controls. In contrast to the increases in sweat chloride, sweat sulfate concentrations in 13 CF patients were reduced to 68 +/- 24% of control values (mean +/- SD, n = 25, p less than 0.001). Sulfate concentrations in sweat may depend on sweat rates, but the rates were not significantly different in the two study groups. Since we have observed a positive correlation between sweat sulfate and sweat chloride excretion in non-CF subjects in earlier studies, we suggest that the decreased sulfate in CF sweat may bear directly on the nature of the anion permeability defect present in the ductal epithelium of the CF sweat gland.

Determination of inorganic sulfate in human saliva and sweat by controlled-flow anion chromatography. Normal values in adult humans

Following the previous demonstration that low concentrations of inorganic sulfate (SO4) in human serum and cerebrospinal fluid can be accurately determined by controlled-flow anion chromatography, the assay has been extended to the quantitation of free SO4 in saliva and sweat by modification of the established methods of sample collection and preparation. Salivary secretions were ultrafiltered to remove macromolecular polyanions that bind irreversibly to the anion-exchange separator column and reduce resolution. Sweat was collected from 22 fasted adult volunteers using a method which utilizes absorbent filter pads applied to the forearm after secretion had been stimulated by pilocarpine iontophoresis. It was necessary to acid wash the filter pads to reduce sulfate contamination. Saliva ultrafiltrate or sweat was diluted and injected onto a Dionex D-10 Ion Analyzer using the standard anion column system. The mean inorganic SO4 concentration in saliva from seventeen adult fasting volunteers was 72 +/- 4 mumol/l (+/- S.E.); the mean SO4 concentration in sweat was 83 +/- 3 mumol/l. Both are significantly less than in matching serum, suggesting that SO4 is actively removed during formation of these glandular secretions. The ion chromatographic assay is shown to be capable of measuring SO4 in biological fluids at concentrations that are otherwise undetectable by conventional assay techniques.

Parenteral nutrition in a premature infant with phenylketonuria

Parenteral nutrition (PN) is now an important facet of the management of the extremely premature infant. However, its effects on those with inherited metabolic disease have not been well documented. We report an infant with classical phenylketonuria (PKU) who had unusually high serum phenylalanine at 12 days of life (5200 mumol; greater than 3.2 SD above our mean for PKU at 10-15 days of age) while on parenteral nutrition, despite a relatively high tolerance for phenylalanine on oral feeds at 3-4 months of life (97-128 mg/kg/day; normal for PKU: less than 90 mg/kg/day). Identification of PKU was somewhat delayed in this child because of failure to recognize that parenteral nutrition provides a phenylalanine load equivalent to or greater than the routine oral formula feeding. Despite the high levels of phenylalanine in the first 2 wk of life, mental and motor development are normal at 16 months of age. This case, the first such reported, suggests the parenteral nutrition in the premature PKU infant is relatively safe, but draws attention to the possible need for phenylalanine-free amino acid infusates for those who require long-term treatment.