Protective effect of proanthocyanidin against oxidative ovarian damage induced by 3-nitropropionic acid in mice.

Oxidative stress, which poses a threat to reproductive health, causes many serious female reproductive diseases. In this study, we investigated whether proanthocyanidins (PC) have a protective effect against oxidative stress-induced ovarian damage. Forty female ICR mice were randomized into 4 groups: a control group, a control plus PC group, a 3-nitropropionic acid (3-NPA) group, and a 3-NPA plus PC group. An ovarian oxidative stress model induced by 3-NPA was constructed using female ICR mice. After the animals were sacrificed, their ovaries were collected to measure reactive oxygen species (ROS) levels, the activities of superoxide dismutase (SOD) and catalase (CAT), and the mRNA expression levels of relevant granulosa cell apoptosis genes (Bcl-2, Bax, Bim, FasL, and caspase-3). We also conducted a histological evaluation of granulosa cell apoptosis and follicular atresia. The results showed that compared to the 3-NPA group, ROS levels and activities of T-SOD and CAT in the 3-NPA plus PC group were significantly decreased (P < 0.05), while the ratio of Bcl-2 to Bax in the 3-NPA plus PC group were significantly increased (P < 0.05). mRNA expression levels of Bim, FasL, and caspase-3 in the 3-NPA plus PC group were significantly decreased (P < 0.05), and the percentage of atretic follicles and granulosa cell apoptosis in the 3-NPA plus PC group was significantly decreased (P < 0.05). Collectively, these data indicate that PC has significant protective effects against damage induced by oxidative stress in mouse ovaries. The mechanisms of protection may be related to antioxidation and apoptosis reduction.

Expression of Frizzled 2 in the mouse ovary during oestrous cycle.

The Wnt/beta-catenin pathway is a conserved signalling pathway that regulates gene expression and controls diverse developmental processes such as cell fate specification, cell proliferation and cell differentiation. To our knowledge, the potential role of this pathway in the adult ovary has been poorly addressed. To this end, we investigated the expression pattern of Frizzled 2 in the mouse ovary during oestrous cycle by real-time Q-PCR, in situ hybridization, Western blotting and immunohistochemistry. In this study, we used uterine wet weight and H3.2 mRNA level as two markers for classification of mouse oestrous cycle. We found that both uterine wet weight and H3.2 mRNA are the highest in the proestrus and decrease from oestrus to diestrus. During oestrous cycle, Frizzled 2 mRNA and protein exhibited the highest level in the proestrus stage and rapidly reduced from oestrus to diestrus. In situ hybridization results showed that the positive signals for Frizzled 2 are highly detected in the oocyte and stroma in proestrus stage, while moderate or weak Frizzled 2 mRNAs are localized in the oocyte, granulosa cells, stroma and corpus luteum from oestrus to diestrus. The localization pattern of Frizzled 2 protein is mostly consistent with its mRNA, but stronger Frizzled 2 proteins are present in the granulosa cells and membrane of oocyte in oestrous cycle. Our data suggest that Frizzled 2 may be involved in regulating follicle growth, oocyte maturation and luteinization during oestrous cycle.

Polycyclic aromatic hydrocarbons in leaf cuticles and inner tissues of six species of trees in urban Beijing.

Leaf samples of six tree species were collected along urban roadsides and a campus site in Beijing for measurement of polycyclic aromatic hydrocarbons (PAHs). PAHs in leaves were attributed to two fractions, leaf cuticles and inner leaf tissues, using sequential extraction. Total concentrations of 16 PAHs in the cuticles and the inner tissues were 69.3+/-64.6 microg g(-1) (d.w.) and 1.07+/-0.2 microg g(-1) (d.w.) at roadside and 57.5+/-52.6 microg g(-1) and 0.716+/-0.2 microg g(-1) on campus, respectively. The lipid-normalized inner tissue PAHs varied from 5.8 microg g(-1) to 15.0 microg g(-1). Similarities in PAH spectra between leaf cuticles and airborne particles and between the inner tissues and gaseous phase imply that airborne particulates and gaseous PAHs are likely the sources of PAHs for cuticles and the inner tissues, respectively. Difficulty in migration of heavier PAHs into inner tissues could be another reason.

Distribution of sorbed phenanthrene and pyrene in different humic fractions of soils and importance of humin.

Contributions of fulvic-humic acids (FA/HA) and humin (HM) to sorption of phenanthrene (PHE) and pyrene (PYR) in a soil were differentiated using a humic separation procedure after multi-concentration sorption experiments. It was found that the amount of solutes in FA/HA did not change significantly after 48 h, while that in HM increased continuously and slowly up to the end of the experimental period (720 h), indicating that HM was the main region for slow sorption. Based on the fitting results using Freundlich equation, it was found that nonlinearity of both solutes was greater in HM than in FA/HA, consistent with the sorption characteristics of individually extracted HA and HM in a separate experiment. The observed nonlinearity of the solute distribution was confirmed by using three other soil samples with organic carbon contents ranging from 0.7 to 7.9%. Distribution dynamics of PHE and PYR among various fractions were also discussed.

Ultraviolet absorbance titration for determining stability constants of humic substances with Cu(II) and Hg(II).

We describe an ultraviolet (UV) absorbance titration method that can be used to determine complexing capacities (C(L)) and conditional stability constants (logK) of humic substances (HSs) with metal ions such as Cu(II) and Hg(II). Two fulvic acids (FA) and one humic acid (HA) were used for this study. UV absorbance of HSs gradually increased with the addition of Cu(II) or Hg(II) after blank correction, and these increases followed the theoretical 1:1 (ligand:metal ion) binding model. The results from the absorbance titration calculation for HSs with Cu(II) and Hg(II) compared well with those from fluorescence quenching titration. The titration of the model compound l-tyrosine with Cu(II) proved the validity of this method, and the K and C(L) were within 2.3% and 7.4% of the fluorescence quenching titration. The results suggest that the UV absorbance titration can be used to study the binding capacities of HSs and/or dissolved organic matter (DOM) with trace metals. The advantages and disadvantages of the absorbance titration method were also discussed.