Exposure to chlorpyrifos interferes with intercellular communication in cumulus-oocyte complexes during porcine oocyte maturation.

Chlorpyrifos (CPF), a widely used organophosphorus pesticide (OP) to control pests has been verified reproductive toxicity on mammalian oocytes. However, limited information exists on its correlation with the dysfunction of the intercellular communication in cumulus-oocyte complexes (COCs). Herein, our study utilized porcine COCs as models to directly address the latent impact of CPF on the communication between cumulus cells (CCs) and oocytes during in vitro maturation. The results demonstrated that CPF exposure decreased the rate of the first polar body (PB1) extrusion and blocked meiosis progression. Notably, the cumulus expansion of CPF-exposed COCs was suppressed significantly, accompanied by the down-regulated mRNA levels of cumulus expansion-related genes. Furthermore, the early apoptotic level was raised and the expression of BAX/BCL2 and cleaved caspase 3 was up-regulated in the CCs of CPF-exposed COCs (p < 0.05). Moreover, CPF exposure impaired mRNA levels of antioxidant enzyme-related genes, induced higher levels of reactive oxygen species (ROS) and reduced the levels of mitochondrial membrane potential (MMP) in CCs (p < 0.05). Additionally, the integrated optical density (IOD) rate (cumulus/oocyte) of calcein and the expression of connexin 43 (CX43) was increased in CPF treatment groups (p < 0.05). As well, CPF exposure reduced the expression levels of FSCN1, DAAM1 and MYO10, which resulted in a significant decrease in the number and fluorescence intensity of transzonal projections (TZPs). In conclusion, CPF inhibited the expansion of cumulus and caused oxidative stress and apoptosis as well as disturbed the function of gap junctions (GJs) and TZPs, which eventually resulted in the failure of oocyte maturation.

Application of optical flow algorithm for drift correction in electron microscopy images.

Transmission electron microscopy (TEM) image drift correction has been effectively addressed using diverse approaches, including the cross correlation algorithm (CC) and other strategies. However, most of the strategies fall short of achieving sufficient accuracy or cannot strike a balance between time consumption and accuracy. The present study proposes a TEM image drift correction strategy that enhances accuracy without any additional time consumption. Unlike the CC algorithm that matches pixels one by one, our approach involves the extraction of multiple feature points from the first TEM image and then uses the Lucas-Kanade (LK) optical flow algorithm to calculate the optical field of these feature points in the subsequent TEM images. The LK algorithm is used to calculate the instantaneous velocity of these feature points, which can help track the movement of the TEM image series. In addition, a high-precision sub-pixel level correction strategy by the utilization of linear interpolation during the correction process is developed in this work. Experimental results confirm that this strategy offers superior accuracy in comparison with the CC algorithm and also is insensitive to the size of the image. Furthermore, we offer a semantic segmentation neural network for electron microscope image pre-processing, thereby expanding the applicability of our methodology.

PAK1 Is Involved in the Spindle Assembly during the First Meiotic Division in Porcine Oocytes.

P21-activated kinase 1 (PAK1), as a member of the PAK family, has been implicated in various functions during somatic mitosis; however, less is known about its role during oocyte meiosis. Herein, we highlight the indispensable role of PAK1 in regulating spindle assembly and cell cycle progression during the first meiotic division of porcine oocytes. First, we found that the activated PAK1 expressed dynamically, and its subcellular localization was tightly associated with the spindle dynamics during meiosis in porcine oocytes. Specific inhibition of PAK1 activity by inhibitor targeting PAK1 activation-3 (IPA-3) led to impaired extrusion of the first polar body (PB1); with most of the IPA-3-treated oocytes arrested at germinal vesicle breakdown (GVBD) and subjected to failure of bipolar spindle formation. However, the adverse effects caused by IPA-3 on oocytes could be restored by reducing disulfide bonds between PAK1 and IPA-3 with dithiothreitol (DTT) treatment. Furthermore, the co-immunoprecipitation assay revealed that PAK1 interacted directly with Aurora A and transforming acidic coiled coil 3 (TACC3), providing an additional explanation for the similar localization of Aurora A and activated PAK1. Additionally, inhibiting the activity of PAK1 decreased the expression of p-Aurora A and p-TACC3; however, the reduced activity of Aurora A and TACC3 could be restored by DTT. In conclusion, PAK1 plays a crucial role in the proper assembly of the spindle during the first meiotic division of porcine oocytes, and the regulation of PAK1 is associated with its effects on p-Aurora A and p-TACC3 expression.

Effects of Ran-GTP/importin ß inhibition on the meiotic division of porcine oocytes.

The Ran-GTP/importin ß pathway has been implicated in a diverse array of mitotic functions in somatic mitosis; however, the possible meiotic roles of Ran-GTP/importin ß in mammalian oocyte meiosis are still not fully understood. In the present study, importazole (IPZ), a small molecule inhibitor of the interaction between Ran and importin ß was used to explore the potential meiotic roles of Ran-GTP/importin ß in porcine oocytes undergoing meiosis. After IPZ treatment, the extrusion rate of the first polar body (PB1) was significantly decreased, and a higher proportion of the oocytes were arrested at the germinal vesicle breakdown (GVBD) stage. Moreover, IPZ treatment led to severe defects in metaphase I (MI) spindle assembly and chromosome alignment during the germinal vesicle (GV)-to-MI stage, as well as failure of metaphase II (MII) spindle reassembly and homologous chromosome segregation during the MI-to-MII stage. Notably, IPZ treatment decreased TPX2 expression and abnormal subcellular localization. Furthermore, the expression levels of aurora kinase A (AURKA) and transforming acidic coiled-coil 3 (TACC3) were significantly reduced after IPZ treatment. Collectively, these data indicate that the interaction of Ran-GTP and importin ß is essential for proper spindle assembly and successful chromosome segregation during two consecutive meiotic divisions in porcine oocytes, and regulation of this complex might be related to its effect on the TPX2 signaling cascades.

TPX2 deficiency leads to spindle abnormity and meiotic impairment in porcine oocytes.

The targeting protein for Xklp2 (TPX2) is a spindle assembly factor, that can stimulate microtubule formation and promote spindle completion during mitosis. However, the role of TPX2 in mammalian oocyte meiotic maturation is still not fully understood. This study was conducted to address the dynamic distribution and potential roles of TPX2 in microtubule nucleation during meiotic maturation in porcine oocytes by microinjecting specific siRNAs. Western blotting results revealed that the expression of TPX2 displayed a lower level from 0 to 22 h of culture, while its expression exhibited a higher level after 28 h of culture. Immunofluorescence staining demonstrated that TPX2 was distributed along the microtubules and enriched in the poles after meiotic spindle formation at the 28 and 44 h of culture. From immunoprecipitation, TPX2 can interact with the microtubule-associated proteins aurora kinase A (AURKA) and transforming acidic coiled-coil 3 (TACC3). Meanwhile, the dynamic changes in the expression and localization of AURKA and TACC3 were highly consistent with TPX2 during meiotic maturation. After knocking down TPX2 by siRNA injection, the proportion of oocytes with aberrant spindles and scattered cytoplasmic actin filaments was significantly increased. In addition, TPX2 depletion markedly downregulated the expression of AURKA and TACC3. Thus, these results suggested that TPX2 is essential for meiotic spindle formation in the porcine oocyte, and that this regulation is related to its effect on AURKA and TACC3 expression.

The effect of cognition and affect on preventive behaviors during the COVID-19 pandemic: a cross-sectional study in China.

BACKGROUND: The global outbreak of COVID-19 has become an international public health crisis. Specific antiviral treatments for COVID-19 are not yet available, and prevention is of particular importance to fight the virus. This study tends to explore and compare the roles of cognitive and affective factors in predicting preventive behavior adoption during the COVID-19 pandemic in China. METHODS: An online survey using a quota sampling method to collect responses from 3000 Chinese adults was conducted from March 2, 2020 to March 23, 2020. Questions included sociodemographic features, coronavirus knowledge, negative emotion, risk perception, and behavioral responses. Multiple regression analyses were conducted to examine the predictors of behavioral responses toward COVID-19. RESULTS: On average, respondents had low levels of knowledge about COVID-19 (the overall correct response rate was 7.5%). Most respondents reported moderate to strong negative emotions towards the virus (3.47 out of 5). The average reported perceived chance of infection was 23.89%. For behavioral responses, respondents reported low frequencies of going out for activities (1.98 out of 4) and high frequencies of taking preventive measures (3.22 out of 4). Behavioral responses toward COVID-19 were found to be determined by cognitive and affective variables. Knowledge was negatively related to frequency of going out for activities (ß = - 0.11, p < .001). Negative emotion (ß = 0.34, p < .001), and risk perception (ß = 0.05, p = .007) were positively associated with going out for activities. The explanatory power of affective variables (ΔR2 = 12.1%) was greater than cognitive variables (ΔR2 = 1.0%). For preventive behaviors, knowledge was positively associated with preventive behaviors (ß = 0.22, p < .001). Negative emotion (ß = - 0.28, p < .001) and risk perception (ß = - 0.05, p = .002) were all negatively associated with preventive measures. Affective variables still showed stronger explanatory power (ΔR2 = 8%) than cognitive variables (ΔR2 = 4.4%) in predicting preventive behaviors. CONCLUSIONS: After the rising period of the COVID-19 outbreak in mainland China, cognitive and affective variables still played important roles in predicting behavioral responses. Compared with cognitive factors, affective factors demonstrated stronger explanatory power in predicting behavioral responses toward COVID-19. The findings may have implications for enhancing individual compliance with guidelines of adopting preventive behaviors in response to COVID-19.

The relationship between government trust and preventive behaviors during the COVID-19 pandemic in China: Exploring the roles of knowledge and negative emotion.

Government trust is known to be associated with preventive practices during pandemics, but few studies have explored the roles of knowledge and negative emotion in conditioning the relationship between trust and preventive behaviors. The aim of this study was to explore the roles of knowledge and negative emotion in conditioning the relationship between trust and preventive measures during the COVID-19 pandemic in China. Data from a cross-sectional survey of 3000 Chinese adults [mean (SD) age 36.93 (12.11) years; 52.4% male], conducted using quota-sampling method (March 2-2020 to March 23-2020), were analyzed. Overall, respondents performed recommended preventive measures more frequently (3.21 out of 4) than excessive preventive measures (2.11 out of 4). Government trust was positively associated with both officially recommended (b = 0.12; 95%CI = 0.18, 0.25) and excessive preventive behaviors (b = 0.07; 95%CI = 0.03, 0.10). The positive relationship between trust and excessive preventive behaviors was found to be statistically significant only among those with low levels of COVID-19 knowledge. Officially recommended preventive behavior is most likely to happen when there is a combination of high levels of government trust and low levels of negative emotion. Therefore, government trust increases both official and excessive (sometimes unscientific) preventive behaviors. Interventions shall aim to enhance people's COVID-19 knowledge and to reduce negative emotions.

Preparation of a nanoporous Cu-Ag solid solution with enhanced sono-Fenton-like catalytic activity.

Uniform 3D bi-continuous nanoporous Cu-Ag solid solution (NPCS) and nanoporous copper (NPC) were successfully synthesized by dealloying Cu70Y28Ag2 and Cu72Y28 metallic glasses, respectively, which was confirmed by using X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The SEM and TEM images show that the ligament size of NPCS (d SEM = 65 nm, d TEM = 45 nm) is much smaller than that of NPC (d SEM = 402 nm, d TEM = 370 nm), which reveals that the ligaments of NPC can be significantly refined by the substitution of 2 at% Ag for Cu in the amorphous precursor. The obtained NPCS exhibits much larger specific surface area and higher total pore volume (S BET = 8.34 m2 g-1, V p = 0.093 cm3 g-1) compared to NPC (S BET = 1.77 m2 g-1, V p = 0.050 cm3 g-1). Furthermore, the catalytic activities of the samples were evaluated by decomposing methyl orange (MO) dye under the irradiation of ultrasound. The results show that NPCS with an extreme fine microstructure displayed superior sono-Fenton-like catalytic activity compared to NPC and commercial copper foil.