Nitric oxide: A possible mediator of ovulation and postovulatory follicle regression in chicken

Effects of dietary supplementation of tomato pomace (Solanum lycopersicum L.) and L-Arg on reproductive performance of aged male broiler breeders

This study aimed to investigate the effects of different dietary supplementation of tomato pomace (TP) and L-arginine (L-Arg) supplementation on sperm characteristics, reproductive performance, and semen biochemical components of aged commercial male broiler breeders. Thirty Ross 308 male broiler breeders (58 wk old) were provided and assigned to 5 dietary treatment groups, including control (CON), 5% TP (TPS-5), 10% TP (TPS-10), 15% TP (TPS-15), and L-Arg supplemented (10% above the recommendation, LAS-10). The results indicated that the semen volume increased in the TPS-15 group compared to that of the LAS-10 (and CON on wk 9) throughout the study (P < 0.05). The sperm concentration significantly increased in TPS-10 and TPS-15 groups in comparison to the other experimental groups. On wk 5 and 7, the sperm viability increased in all TPS groups compared to the CON and LAS-10, while on wk 9, it only increased in the TPS-10 group in comparison to the LAS-10 group (P < 0.05). The hypo-osmotic swelling test decreased in the LAS-10 group compared to the other experimental groups on wk 5 and all TPS groups on wk 7 and 9 (P < 0.05). The sperm total motility and forward progressive motility decreased in the LAS-10 group compared to the other experimental groups (P < 0.05). In contrast, unprogressive motility and immotile sperms were increased in the LAS-10 group compared to the other experimental groups (P < 0.05). In addition, the sperm penetration and fertility rate increased in TPS-10 and TPS-15 groups in comparison to CON and LAS-10 groups (P < 0.05). However, hatchability was reduced in the LAS-10 group (P < 0.05). The semen adenosine triphosphate increased in TPS-10, TPS-15, and LAS-10 groups compared to the CON (P < 0.05). Finally, the semen TAC and superoxidase dismutase decreased in the LAS-10 group (P < 0.05), while the glutathione peroxidase increased in the TPS-15 group (P < 0.05). In conclusion, 15% dietary TPS is recommended to improve the reproductive performance of aged commercial male broiler breeders.

Changes in Production Parameters, Egg Qualities, Fecal Volatile Fatty Acids, Nutrient Digestibility, and Plasma Parameters in Laying Hens Exposed to Ambient Temperature

The present study was undertaken to investigate the impact of heat stress on nutrient digestibility and tibia and reproductive traits, and changes in laying performance, egg qualities, fecal volatile fatty acids, and plasma parameters in laying hens. One-hundred twenty 52-week-old laying hens were raised in three temperature-controlled facilities with constant humidity (50% RH), either normal temperature (LT; 22°C) or heat stress considered being moderate (MT; 27°C) or severe (HT; 32°C) for 42 days. Feed intakes were consistently low (p < 0.01) in HT hens compared with those in LT or MT over the period of 42 days. Egg production kept markedly (p < 0.05) or numerically (p > 0.05) low in hens exposed to HT vs. LT or MT. Egg mass and egg weight were consistently low (p < 0.01) in hens exposed to HT compared with those raised under LT or MT. On the other hand, feed conversion ratio and frequency of dirty and cracked eggs were not significantly affected (p > 0.05) during the experimental period. HT-exposed hens consistently had lowered (p < 0.05) eggshell thickness and breaking strength, eggshell weight, and plasma Ca, P, and Mg levels compared with LT- or MT-treated hens. HT hens had lower (p < 0.01) relative oviduct weight and less number of large yellow follicles compared with those raised under LT or MT conditions at 42 days. Tibia traits measured at 42 days were not affected by any of heat treatments. Fecal volatile fatty acids tended to be higher in HT-exposed laying hens throughout the experiment. It was noted that digestibilities of neutral detergent fiber and dry matter were lowest (p < 0.05) in hens exposed to HT vs. LT or MT environments. Our study suggests that heat stress could lower laying performance, egg quality, and physiological parameters that are coupled with alterations in gut metabolites and mineral/lipid metabolism. The findings emerged from this study will help us design the nutritional and environmental strategies to mitigate the negative effect of heat stress on laying hens.

Controlling chronic low-grade inflammation to improve follicle development and survival

Chronic low-grade inflammation is one cause of follicle development disturbance. Chronic inflammation exists in pathological conditions such as premature ovarian failure, physiological aging of the ovaries, and polycystic ovary syndrome. Inflammation of the whole body can affect oocytes via the follicle microenvironment, oxidative stress, and GM-CSF. Many substances without toxic side-effects extracted from natural organisms have gradually gained researchers' attention. Recently, chitosan oligosaccharide, resveratrol, anthocyanin, and melatonin have been found to contribute to an improvement in inflammation. This review discusses the interrelationships between chronic low-grade inflammation and follicle development, the underlying mechanisms, and methods that may improve follicle development by controlling the level of chronic low-grade inflammation.

Coherent apoptotic and autophagic activities involved in regression of chicken postovulatory follicles

After ovulation in mammals, rupture of mature follicles is reorganized into the corpus luteum that secrets progesterone (P₄) to stimulate endometrial development. The situation in birds differs considerably. Beyond ovulation the ruptured avian follicle forms a postovulatory follicle (POF) that is not considered analogous to mammalian corpus luteum. The function and regression mechanisms of avian POFs remain poorly understood. Here we investigated the changes in apoptotic and autophagic activities that were involved during POF degradation. Results showed that the structure and secretory function of POF3 manifested the most apparent deterioration during whole processes of regression. A TUENL assay revealed that the granulosa layer maintained longer viability than the theca layer. Importantly, mitochondrial apoptosis and endoplasmic reticulum (ER) stress-associated genes and proteins reached their highest levels in the granulosa cells of POF3. Beclin1 was distributed mainly in theca cells and coupled with LC3β-II accumulation, Sequestosome-1 (p62) degradation and Beclin1 elevation confirmed that autophagic activity had increased dramatically in the theca layer of POFs. These results indicate that the apoptosis of the granulosa cells from POFs occurs by mitochondrial apoptosis and ER stress and that a coherence of Beclin1-induced autophagy and caspase-induced apoptosis results in regression of theca layers of avian POFs.

Involvement of matrix metalloproteinases (MMP-2, -7, -9) and their tissue inhibitors (TIMP-2, -3) in the regression of chicken postovulatory follicles

The study was undertaken to examine mRNA expression and localization of selected matrix metalloproteinases (MMPs) and their tissue inhibitors (TIMPs), and the activity of MMPs in chicken postovulatory follicles (POFs) during their apoptotic regression. Apoptotic cells and apoptosis-related caspase expression and activity were examined as well. Chickens were sacrificed 2 h and 21 h after ovulation, and five POFs (POF1 to POF5) were isolated from the ovaries. It was found that the number of apoptotic cells (TUNEL-positive) increased along with follicle regression. The relative expression (RQ) of caspase-2, -3, -8 and -9 mRNA increased (P < 0.05) in POF5, while the activity of all examined caspases elevated gradually (approximately 80-150%) reaching the highest level in POF3, and then slowly decreased to the value noted in POF1 (P < 0.05 - P < 0.001). Real-time polymerase chain reaction revealed different expression of MMP-2, -7, -9 and TIMP-2 and -3 on mRNA levels, and activity assay showed the changes in activity of MMP-2 and -9 in the POFs. Regression of the follicles was accompanied predominantly by an increase in the relative expression of MMP-2, and a decrease in TIMP-2 and -3 mRNAs (P < 0.05 - P < 0.001). The activity levels of MMP-2 and -9 showed pronounced changes during the examined period. During follicle regression elevated activity of MMP-2 and -9 was found (P < 0.05 - P < 0.001). Immunohistochemistry demonstrated tissue- and follicle-dependent immunoreactivity of the examined members of the MMP system. In summary, the results showing the apoptotic regression-related changes as well as tissue-dependent differences in the expression of selected MMPs and TIMPs, and activity of MMP-2 and MMP-9, point to the significance that these molecules might participate in the complex orchestration of chicken POF regression.

PCNA and apoptosis during post-spawning ovarian remodeling in the teleost Oreochromis niloticus

The balance between cell proliferation and apoptosis is crucial for tissue development and homeostasis. The present study investigated the contribution of proliferating cell nuclear antigen (PCNA) and apoptosis during ovarian remodeling after spawning in the Nile tilapia Oreochromis niloticus. Breeding females were kept in controlled conditions and ovary samples were collected weekly for TUNEL assay, immunohistochemistry for PCNA and caspase-3 and morphometric analysis. During the follicular growth, PCNA labeled mainly the nuclei of oocytes and follicular cells in a high proportion of follicles especially in primary growth, while a low occurrence of apoptosis in follicular and theca cells was detected. At 0-3 days post-spawning, post-ovulatory follicles showed no proliferative activity, however the follicular cells exhibited high rates of apoptosis. At 7-10 days, PCNA labeled the thecal cells in a low proportion of post-ovulatory follicles, which showed follicular cells with lower rates of apoptosis. PCNA labeled mainly the theca in the advanced and late stages of atretic follicles, while the follicular cells exhibited a significant increase of apoptosis along follicular atresia. We concluded that PCNA and apoptosis work cooperatively to ensuring the success of follicle development and maintaining of tissue homeostasis during follicular growth. PCNA and apoptosis are also essential mechanisms in the follicular regression during post-spawning ovarian recovery in the Nile tilapia.

Nitric oxide in follicle development and oocyte competence

Apart from its well-known role in regulating endothelial function, in mammals, nitric oxide (NO) is an important signaling molecule involved in many processes, regulating different biological functions. It has been demonstrated that NO plays a role in the physiology of the reproductive system, where it acts in controlling the activity of reproductive organs in both sexes. In the female of several animal species, experimental data suggest the presence of an intraovarian NO-generating system, which could be involved in the control of follicular development. The role of NO in regulating follicular atresia by apoptosis is still controversial, as a dual action depending mostly on its concentration has been documented. NO also displays positive effects on follicle development and selection related to angiogenic events and it could also play a modulatory role in steroidogenesis in ovarian cells. Both in monovulatory and poliovulatory species, the increase in PGE2production induced by NO via a stimulatory effect on COX-2 activity appears to be a common ovulatory mechanism. Considerable evidence also exists to support an involvement of the NO/NO synthase system in the control of meiotic maturation of cumulus–oocyte complexes.

Analysis of candidate genes underlying two epistatic quantitative trait loci on SSC12 affecting litter size in pig

The previous results from a genome scan for total number of piglets born and number of piglets born alive in a F(2) Iberian by Meishan intercross showed several single and epistatic QTL. One of the most interesting results was obtained for SSC12, where two QTL affecting both traits showed epistatic interaction. In this study, we proposed two genes (SLC9A3R1 and NOS2) as biological and potentially positional candidates underlying these QTL. Both cDNAs were characterized and 23 polymorphisms were detected. A chromosome scan was conducted with 12 markers, plus one SNP in SLC9A3R1 and one in NOS2, covering 110 cM of SSC12. The epistatic QTL (QTL1 at 15 cM and QTL2 at 97 cM) were confirmed, and SLC9A3R1 and NOS2 were mapped around the QTL1 and QTL2 regions respectively. Several SNPs in both genes were tested with standard animal model and marker assisted association tests. The most significant results were obtained with the NOS2 haplotype defined by one missense SNP c.2192C > T (Val to Ala) and a 15 bp duplication at the 3'UTR. This duplication seems to include AU-rich elements, and could be a target site for miRNA, therefore there are statistical and biological indications to consider this haplotype as the potential causal mutation underlying QTL2. SLC9A3R1 results were not conclusive. Although the interaction between the SNPs was not significant, we cannot reject the possibility of interaction of the NOS2 haplotype with other polymorphisms closely linked to the SL9A3R1 SNPs analysed.

Spatial expression of chemokines and cytokines mRNA in the largest preovulatory follicle of chicken

In the present experiment, we studied the spatial expression profiles of chemokines and cytokines mRNA in the granulosa (F1Gr) and theca (F1Th) layers of the largest preovulatory follicle in chicken using semi-quantitative PCR. The mRNAs of IL-1beta, IL-6, GM-CSF, chCXCLi2, chCCLi2, chCCLi4, chCCLi7, IFN-gamma, IL-4, IL-13, IL-10 and TGF-beta2 were expressed in the granulosa (F1Gr) and theca (F1Th) layers of the largest preovulatory follicle. However, the transcripts of IL-2 were not detected in any of the samples tested. Significantly higher levels of IL-6 and GM-CSF mRNA expression were noticed in F1Gr when compared to F1Th layer. Expression of chCXCLi2, a CXC chemokine, was almost similar in F1Gr and F1Th layers. However, the expression of CCL chemokines i.e. chCCLi2, chCCLi4, chCCLi7 mRNAs were almost 2 folds higher in F1Th layer in comparison to F1Gr layer. The expression of Th2 cytokines (IL-4 and IL-13) mRNA was noticed in F1Gr and F1Th layers with higher levels in the former. Expression of IFN-gamma mRNA was noticed in F1Gr and F1Th layers. Significantly higher level of TGF-beta2 expression was observed in F1Th in comparison to F1Gr layer. It was concluded from the present study that the mRNA expression of cytokines and chemokines are differentially regulated in the granulosa and theca layers of the largest preovulatory follicle in chicken.