Metformin improves ovarian function and increases egg production in broiler breeder hens

In brief

The pathophysiology of the ovarian dysfunction encountered in broiler breeder hens remains poorly understood but is similar to a condition in women known as polycystic ovary syndrome. This study reveals that metformin may provide a cheap and effective method of improving ovarian function in broiler breeder hens.

Abstract

Broiler breeder hens, the parent stock of commercial broiler chickens, have poor reproductive efficiency associated with aberrant and excessive recruitment of ovarian follicles which results in sub-optimal egg production, fertility, and hatchability. The reproductive dysfunction observed in these hens resembles polycystic ovary syndrome in women, a condition wherein metformin is prescribed as a treatment. The main objectives of this study were to determine the effect of metformin on body weight, abdominal fat pad weight, ovarian function, and plasma steroid hormone concentrations. Broiler breeder hens were treated with 0, 25, 50, or 75 mg/kg body weight of metformin mixed in the diet for 40 weeks (n = 45 hens/treatment; 2565 weeks of age). At 65 weeks of age, hens that received the highest dose of metformin had significantly lower body and abdominal fat pad weights (P < 0.05) than the control. Metformin treatment, at all levels, normalized the preovulatory and prehierarchical ovarian follicular hierarchy. Metformin (50 or 75 mg/kg body weight) significantly increased the total number of eggs laid per hen during the entire production period and these hens had significantly greater fertility and hatchability at 65 weeks of age compared to the control (P < 0.05). Metformin treatment at all levels altered the plasma profile of reproductive hormones, with significantly lower plasma testosterone concentrations and a decreased testosterone to androstenedione ratio in hens that received metformin (P < 0.05). Future studies should focus on the mechanisms underlying the beneficial effects of metformin in improving the reproductive efficiency of broiler breeder hens.

Feeding laying hens docosa hexaenoic acid-rich microalgae oil at 40 g/kg diet causes hypotriglyceridemia, depresses egg production, and attenuates expression of key genes affecting hepatic triglyceride synthesis and secretion, but is rescued by dietary co-supplementation of high-oleic sunflower oil

The primary goal of this study was to investigate the effect of feeding White Leghorn hens graded levels of a docosahexaenoic acid (DHA)-rich microalgae oil (MAO) on productive performance and enrichment of eggs with very long-chain (VLC) omega-3 (n-3) polyunsaturated fatty acids (PUFA). Forty-nine-week-old hens (8 per diet) were fed the following diets for 28 d: 1) A corn-soybean meal-based diet with no supplemental oil (CON); 2) CON + 10 g/kg MAO; 3) CON + 20 g/kg MAO; 4) CON + 30 g/kg MAO; 5) CON + 40 g/kg MAO; 6) CON + 40 g/kg MAO + 20 g/kg high-oleic sunflower oil (HOSO); and 7) CON + 40 g/kg MAO + 40 g/kg HOSO. Diets 6 and 7 were included because we previously reported that co-feeding high-oleic acid oils with n-3 PUFA-containing oils attenuated egg yolk n-3 PUFA contents vs. feeding hens the n-3 oils alone. All data were collected on an individual hen basis. Egg VLC n-3 PUFA enrichment plateaued, in terms of statistical significance, at the 30 g/kg MAO level (266 mg/yolk). Hens fed 40 g/kg MAO had greatly attenuated measures of hen performance, marked liver enlargement, an altered ovarian follicle hierarchy, greatly lowered circulating triglyceride levels, and depressed hepatic expression of key genes involved in triglyceride synthesis and secretion. As compared to hens fed 40 g/kg MAO alone, feeding hens 40 g/kg MAO co-supplemented with HOSO (Diets 6 and 7) restored egg production, ovarian morphology, and all other measures of hen productive performance to CON levels, elevated plasma triglyceride levels, prevented liver enlargement, and increased the hepatic expression of key genes involved in triglyceride synthesis and secretion. In conclusion, MAO can greatly enrich hens' eggs with VLC n-3 PUFA, but its recommended dietary inclusion should not exceed 20 g/kg. This would allow for near-maximal yolk VLC n-3 PUFA enrichment without impairing hen productive performance, altering the ovarian follicle hierarchy or, based on the work of others, presumably imparting off-flavors in the egg.

Metformin attenuates steroidogenesis in ovarian follicles of the broiler breeder hen

The follicular hierarchy in broiler breeder chicken ovary is often deranged due to excessive ovarian follicular recruitment, resulting in a condition that resembles polycystic ovary syndrome (PCOS) in women. Metformin is widely prescribed to correct PCOS and has been shown to affect granulosa cell functions in humans and rodent models. The objectives of this study are to determine the effects of metformin on signal transduction pathways, gene expression related to steroidogenesis, and progesterone secretion from granulosa cells isolated from the most recently recruited preovulatory and prehierarchical follicles of broiler breeder chickens. Granulosa cells were treated with 0, 1, 10, or 20 mM of metformin in the presence of FSH. The abundance of pAMPK, pACC, pERK, and pAkt was determined by Western blotting. The expression of genes related to progesterone biosynthesis was quantified by qPCR. Progesterone concentrations in culture media were quantified by ELISA. Metformin treatment did not have an effect on the abundance of pAMPK and pACC in prehierarchical follicles but significantly decreased the abundance of pERK and pAkt in a dose-dependent manner in preovulatory and prehierarchical follicles. The expression of genes related to steroidogenesis such as FSHR, STAR, CYP11A1, HSD3B, and progesterone secretion was significantly decreased in response to metformin treatment in a dose-dependent manner. Our data suggest that metformin treatment attenuates progesterone secretion via AMPK-independent pathways in granulosa cells of prehierarchical and preovulatory follicles of broiler breeder hens. Further studies are required to determine if metformin administration could ameliorate ovarian dysfunction in obese broiler breeder hens.

Mining the adenovirus virome for oncolytics against multiple solid tumor types

Although there are 55 serotypes of adenovirus (Ad) that infect humans, Ad serotype 5 (Ad5) is the most widely studied because of the availability of commercial kits for its genetic manipulation. In fact, engineered Ad 5 is currently being used in all of the 87 global clinical trials utilizing Ad for the treatment of cancer. Unfortunately, Ad5 is one of the most seroprevalent serotypes, meaning that this virus has to confront additional immunological barriers to be effective in Ad5-immune patients. In this work, we compare Ad5 to 13 other adenoviral serotypes from species B, C, D and E for oncolytic potential in both immunodeficient mouse and immunocompetent hamster models. Our results indicate that species D Ads are not effective oncolytics against most solid tumors. Conversely, lower seroprevalent Ad6 and Ad11 had anti-cancer activity comparable to Ad5. This work strongly supports the consideration of Ad6-based oncolytic therapies for the treatment of breast, ovarian, kidney and liver tumors.

Effects of community composition and growth rate on aquifer biofilm bacteria and their susceptibility to betadine disinfection

Biofilm formation and function was studied in mixed culture using 20 bacterial strains isolated from a karst aquifer. When co-cultured in a glucose-limited chemostat, Vogesella indigofera and Pseudomonas putida were the dominant planktonic and biofilm organisms respectively. Biofilm formation and resistance to the iodine disinfectant betadine were then studied with monoculture and binary cultures of V. indigofera and P. putida and a 20-strain community. Biofilm population size [measured as colony-forming units (CFU) cm(-2)] increased with increasing species diversity. Significantly larger populations formed at dilution rates (DRs) of 0.0083 h(-1) than at 0.033 h(-1). P. putida populations were higher and V. indigofera lower in binary than in monoculture biofilms, suggesting that P. putida outcompeted V. indigofera. In binary biofilms, V. indigofera, a betadine-resistant organism, enhanced the survival of P. putida, a betadine-susceptible organism. In the 20-strain biofilms, this protective effect was not observed because of low concentrations of V. indigofera (< 1% of the total population), suggesting that resistant organisms contribute to overall biofilm disinfectant resistance. Growth at 0.033 h(-1) enhanced survival of V. indigofera biofilms against betadine. Although DR did influence survival of the other communities, its effects were neither consistent nor significant. All told, biofilm formation and betadine resistance are complex phenomena, influenced by community composition, growth rate and betadine concentration.

AtFim1 is an actin filament crosslinking protein from Arabidopsis thaliana

ATFIM1 is a widely expressed gene in Arabidopsis thaliana that encodes a putative actin filament-crosslinking protein, AtFim1, belonging to the fimbrin/plastin class of actin-binding proteins. In this report we have used bacterially expressed AtFim1 and actin isolated from Zea mays pollen to demonstrate that AtFim1 functions as an actin filament-crosslinking protein. AtFim1 binds pollen actin filaments (F-actin) in a calcium-independent manner, with an average dissociation constant (Kd) of 0.55+/-0.21 microM and with a stoichiometry at saturation of 1:4 (mol AtFim1 : mol actin monomer). AtFim1 also crosslinks pollen F-actin by a calcium-independent mechanism, in contrast to crosslinking of plant actin by human T-plastin, a known calcium-sensitive actin-crosslinking protein. When micro-injected at high concentration into living Tradescantia virginiana stamen hair cells, AtFim1 caused cessation of both cytoplasmic streaming and transvacuolar strand dynamics within 2-4 min. Using the 'nuclear displacement assay' as a measure of the integrity of the actin cytoskeleton in living stamen hair cells, we demonstrated that AtFim1 protects actin filaments in these cells from Z. mays profilin (ZmPRO5)-induced depolymerization, in a dose-dependent manner. The apparent ability of AtFim1 to protect actin filaments in vivo from profilin-mediated depolymerization was confirmed by in vitro sedimentation assays. Our results indicate that AtFim1 is a calcium-independent, actin filament-crosslinking protein that interacts with the actin cytoskeleton in living plant cells.

Immunotoxicity of ochratoxin A to growing gilts

Ochratoxin A (OA) was incorporated in the diets of growing gilts (mean body weight, 20.1 kg) at a concentration of 2.5 mg of OA/kg of feed and was fed continuously for 35 days. Humoral and cell-mediated immunologic measurements were evaluated to determine the effects of OA on immune function in swine. Cutaneous basophil hypersensitivity to phytohemagglutinin (PHA), delayed hypersensitivity to tuberculin, PHA-induced lymphocyte blastogenesis, interleukin-2 production, total and isotype immunoglobulin concentrations, antibody response to chicken RBC, and macrophage activation were used to evaluate immune function. Gilts treated with OA had reduced cutaneous basophil hypersensitivity response to PHA, reduced delayed hypersensitivity to tuberculin, decreased stimulation index for lymphoblastogenesis, decreased interleukin-2 production when lymphocytes were stimulated with concanavalin A, and decreased number and phagocytic activity of macrophages. Differences were not observed for total and isotype immunoglobulin concentrations, or humoral hemagglutination (chicken RBC) titer. These data indicate that OA may suppress cell-mediated immune response in growing swine.

Effects on growth and sporulation of inactivation of a Bacillus subtilis gene (ctc) transcribed in vitro by minor vegetative cell RNA polymerases (E-sigma 37, E-sigma 32)

The E-sigma 37-transcribed gene ctc was inactivated by a site-specific insertion into the Bacillus subtilis chromosome. The resulting mutation inhibited sporulation by 95% at elevated temperatures (48 degrees C). If the ctc- mutation is placed in a strain that carries a mutation in the closely linked but distinct spoVC gene, ctc now affects both growth and sporulation at elevated temperatures. Growth of the ctc- spoVC285 strain was transiently inhibited when exponentially growing cultures were shifted from 37 degrees C to 48 degrees C. A similar, but less pronounced "growth lag", was also seen in a B. subtilis strain carrying only the spoVC-285 mutation. This finding suggests that both the ctc and spoVC products function in vegetatively growing B. subtilis.

The Bacillus subtilis spoIIG operon encodes both sigma E and a gene necessary for sigma E activation

A sporulation-specific sigma factor of Bacillus subtilis (sigma E) is formed by a proteolytic activation of a precursor protein (P31). Synthesis of the precursor protein is shown to be abolished in B. subtilis mutants with plasmid insertions as far as 940 base pairs upstream of the P31 structural gene (sigE), and processing of P31 to sigma E is blocked by a deletion in this upstream region. These results substantiate the view that sigE is the distal member of a 2-gene operon and demonstrate that the upstream gene (spoIIGA) is necessary for sigma E formation.

Secretion of immunoglobulin A by human milk leukocytes initiated by surface membrane stimuli

Some of the requirements for release of immunoglobulin A (IgA) from human milk leukocytes during phagocytosis were investigated. The role of particle adherence in IgA release was studied by using an in vitro model of frustrated phagocytosis in which human milk leukocytes were incubated with latex particles too large to ingest. Release of IgA was significantly increased from control values within 30 min in these leukocytes. A similar increment in IgA release also occurred when human milk leukocytes were incubated with other surface membrane stimuli, e.g., NFMP and phorbol. No increase in IgA release was found, however, in cells incubated with zymosan-activated serum. In addition, the release of IgA was blocked by inhibitors of actin filaments (cytochalasin B) and microtubules (colchicine). Thus, IgA is released from human milk leukocytes by secretory mechanisms that are initiated by certain membrane stimuli, some of which are shared by peripheral blood neutrophils and monocytes. Because human milk leukocytes appear to be refractory to C5a or other activated complement components and are blocked by cytochalasin B, it appears that these unusual cells may be uniquely adapted to play a role in the immunologic protection of the neonate.

Secretion of immunoglobulin A by human milk leukocytes initiated by surface membrane stimuli

Some of the requirements for release of immunoglobulin A (IgA) from human milk leukocytes during phagocytosis were investigated. The role of particle adherence in IgA release was studied by using an in vitro model of frustrated phagocytosis in which human milk leukocytes were incubated with latex particles too large to ingest. Release of IgA was significantly increased from control values within 30 min in these leukocytes. A similar increment in IgA release also occurred when human milk leukocytes were incubated with other surface membrane stimuli, e.g., NFMP and phorbol. No increase in IgA release was found, however, in cells incubated with zymosan-activated serum. In addition, the release of IgA was blocked by inhibitors of actin filaments (cytochalasin B) and microtubules (colchicine). Thus, IgA is released from human milk leukocytes by secretory mechanisms that are initiated by certain membrane stimuli, some of which are shared by peripheral blood neutrophils and monocytes. Because human milk leukocytes appear to be refractory to C5a or other activated complement components and are blocked by cytochalasin B, it appears that these unusual cells may be uniquely adapted to play a role in the immunologic protection of the neonate.

Relationship between phagocytosis and immunoglobulin A release from human colostral macrophages

Macrophages and neutrophils that contain mainly secretory immunoglobulin A (IgA) comprise the majority of cells in human colostrum. These cell populations were separated and analyzed for their ability to release total IgA and secretory IgA when stimulated to phagocytose. Colostral macrophages phagocytosed opsonized bacteria and nonopsonized latex particles; at the same time, IgA was released. Neutrophils poorly phagocytosed opsonized bacteria but actively phagocytosed latex particles. In contrast to the macrophages, the neutrophils did not release IgA, even after active phagocytosis of latex. Consequently, colostral macrophages are the main source of IgA released from colostral leukocytes when these cells are exposed to organisms or particles that are phagocytosed. A function for colostral neutrophils which sequester IgA is proposed.

Immunoglobulin A and secretory immunoglobulin A antibodies to purified type 1 Klebsiella pneumoniae pili in human colostrum

Immunoglobulin A antibodies with binding specificity for purified Klebsiella pneumoniae type 1 pili were detected by an enzyme-linked immunosorbent assay in 20 of 21 human samples (95%). The concentrations of secretory immunoglobulin A antibody in colostrum directed against the pili were calculated by comparison of experimental enzyme-linked immunosorbent assay values with values obtained from known secretory immunoglobulin A concentrations. The presence of antibodies to K. pneumoniae type 1 pili was confirmed by double diffusion-gel studies with selected specimens of colostrum. This study shows that in the majority of human colostral samples examined, secretory immunoglobulin A antibodies with specificity for K. pneumoniae type 1 pili can be commonly found in variable, but frequently high, concentrations.

Enhanced immunoglobulin, A release from human colostral cells during phagocytosis

Human colostral leukocytes were investigated for their ability to release immunoglobulin A during phagocytosis of latex particles, heat-killed Candida albicans, or live Escherichia coli. Leukocytes readily phagocytosed latex or serum-opsonized candida or the E. coli. Colostral fluid was also opsonic for yeast and bacteria. Immunoglobulin release, which consisted mainly of secretory immunoglobulin A, began during the first 15 min of incubation with latex, opsonized yeast, or opsonized bacteria. Release was significantly increased from control levels by 30 or 60 min. The release of immunoglobulin A could be inhibited by incubating leukocytes at 4 degrees C. We conclude that phagocytosis and immunoglobulin A release by human colostral leukocytes are related. The data support the hypothesis that colostral leukocytes may play an active role in protecting infants from pathogenic microorganisms.

Capillary basement membrane thickening associated with the small intestine of the ketonuric diabetic Chinese hamster

Morphometric evaluation of intestinal capillary basement membranes demonstrated a significant thickening in those of ketonuric diabetic Chinese hamsters compared to age-matched nondiabetic controls. A highly significant correlation was found between increased capillary basement membrane thickness and progression of ketonuria. Age was also positively related to elevation in capillary basement membrane thickness of control and diabetic hamsters. Capillary basement membrane thickness of diabetic animals was not significantly related to a combination of progredient ketonuria and advance in age.