Atomic-scale structures and dynamics at the growing calcite step edge investigated by high-speed frequency modulation atomic force microscopy.

We have investigated the calcite growth mechanism by directly imaging atomic-scale structural changes at the growing step edges with high-speed frequency modulation atomic force microscopy (HS-FM-AFM). We compared the results with those previously obtained during dissolution, where a transition region (TR) consisting of a Ca(OH)2 monolayer was found to be formed along the step edges as an intermediate state. We found that the TR is created not only during dissolution but also during the growth process. Steps with and without a TR coexist with a ratio of 7 : 3 in both dissolution and growth, implying that their primary reaction pathways should involve TR formation. While all the dissolving steps show a linear shape, the growing steps additionally present a complex non-linear shape with many kinks. The TRs formed along the linear steps present a fixed and uniform width, while those along the complex steps present a non-uniform and dynamically varying width. The acute and obtuse steps show similar TR formation probability, TR width, and step velocity during growth, while a TR is preferentially formed along an acute step during dissolution. For both step types, TRs during growth are wider than those during dissolution. Based on these findings, we present possible reaction pathways triggered by the adsorption of either CO2 or HCO3- for the elementary steps in calcite growth.

Effects of Hochuekkito, a traditional Japanese medicine (Kampo), on reproduction of aging female mice.

PURPOSE: To determine the potentials of Hochuekkito (HET) treatment for aging infertility. METHODS: Mice at 36 weeks of age were fed without (control, n = 40) or with low (100 mg/kg/day, n = 24) and high (1000 mg/kg/day, n = 38) doses of HET for 12 weeks. Aging animals at 48 weeks of age were used for in vitro fertilization-embryo transfer (IVF-ET), and their ovaries were subjected to histological and quantitative inflammation analyses. RESULTS: HET administration decreased transcript levels of ovarian inflammatory markers, interleukin 6 (IL-6), IL-1ß, tumor necrosis factor (TNF)-α, and interferon-gamma (IFN-γ) but suppressed ovulation rates and the number of ovulated oocytes in aging mice. Furthermore, HET treatment decreased the rates of oocytes maturation and fertilization and the cumulus-cell expression of TNF-α-induced protein 6 and epidermal growth factor receptor. After IVF-ET, no improvement of declined live offspring rate by aging was achieved by HET administration, although there were no adverse effects on embryo development and implantation as well as gross morphology and bodyweight of pups. CONCLUSION: Present study indicated HET treatment interfered with ovulation and fertilization in aging mice without affecting ovarian follicle development. No improvement on the age-associated decline of live offspring rate and follicle development was achieved after HET treatment.

Dissolution Processes at Step Edges of Calcite in Water Investigated by High-Speed Frequency Modulation Atomic Force Microscopy and Simulation.

The microscopic understanding of the crystal growth and dissolution processes have been greatly advanced by the direct imaging of nanoscale step flows by atomic force microscopy (AFM), optical interferometry, and X-ray microscopy. However, one of the most fundamental events that govern their kinetics, namely, atomistic events at the step edges, have not been well understood. In this study, we have developed high-speed frequency modulation AFM (FM-AFM) and enabled true atomic-resolution imaging in liquid at ∼1 s/frame, which is ∼50 times faster than the conventional FM-AFM. With the developed AFM, we have directly imaged subnanometer-scale surface structures around the moving step edges of calcite during its dissolution in water. The obtained images reveal that the transition region with typical width of a few nanometers is formed along the step edges. Building upon insight in previous studies, our simulations suggest that the transition region is most likely to be a Ca(OH)2 monolayer formed as an intermediate state in the dissolution process. On the basis of this finding, we improve our understanding of the atomistic dissolution model of calcite in water. These results open up a wide range of future applications of the high-speed FM-AFM to the studies on various dynamic processes at solid-liquid interfaces with true atomic resolution.

Short-term resveratrol treatment restored the quality of oocytes in aging mice.

The quality of oocytes declines by aging, resulting in their low competences for fertility. Here, resveratrol treatment showed increases in the rates of implantation and live offspring as well as decreases in the abortion rate as short as one week after treatment, although the number of ovulated oocytes and the rates of fertilization and blastocyst formation were not changed following resveratrol treatment. Resveratrol treatment did not cause abnormalities mouse estrous cycles and body weights. No abnormality was detected in both fetuses and placentas after 22 weeks of resveratrol treatment and the fetuses had normal fertility. Positive correlations were found between serum resveratrol levels and pregnancy and live offspring rates as well as ovarian expression levels of Sirt1, Sirt3, Sirt4, Sirt5, and Sirt7. The mitochondrial membrane potential and ATP content but not copy number of mitochondrial DNA in oocytes was increased in aging mice with resveratrol treatment. In conclusion, we demonstrated the restoration of oocyte quality in aging mice in addition to the prevention of their quality decline during aging by restoring mitochondrial functions by resveratrol treatment without adverse effects in the animals and their offspring.

Pre-ovulatory LH/hCG surge decreases C-type natriuretic peptide secretion by ovarian granulosa cells to promote meiotic resumption of pre-ovulatory oocytes.

BACKGROUND: In mammalian follicles, oocytes are arrested at the diplotene stage of prophase I until meiotic resumption following the LH surge. Recently, C-type natriuretic peptide (CNP), encoded by natriuretic peptide precursor type C (NPPC) was found to suppress mouse oocyte maturation by promoting cyclic guanosine 5'-monophospate (cGMP) production in cumulus cells. However, regulation of NPPC/CNP expression during the pre-ovulatory period and their regulation by the LH surge have not been investigated. METHODS AND RESULTS: Based on genome-wide analysis of DNA microarray data sets using samples from periovulatory ovaries, we found increases in NPPC transcripts in granulosa cells during pre-ovulatory follicle growth in mice and a rapid decline induced by the pre-ovulatory LH/hCG stimulation. Treatment of pre-ovulatory animals with hCG decreased ovarian CNP content. In isolated ovarian cells, NPPC mRNA was predominantly expressed in mural granulosa cells exhibiting similar regulation following gonadotrophin treatment. In cultured mouse pre-ovulatory follicles, meiosis resumption in oocytes by hCG treatment was accompanied by decreases in NPPC transcript levels. In cultured mouse cumulus cell-oocyte complexes, CNP treatment inhibited the resumption of meiosis with increases in cGMP levels in both cumulus cells and oocytes. In human ovaries, CNP levels in ovarian follicular fluid were also decreased following treatment of patients with an ovulatory dose of hCG. CONCLUSIONS: Our findings demonstrate gonadotrophins regulation of NPPC/CNP expression in mouse and human ovaries and confirm the role of CNP as a potent paracrine oocyte maturation inhibitor.

Fertility Preservation in Patients with Severe Ovarian Dysfunction.

Ovarian function progressively declines during aging and in some pathophysiological conditions including karyotype abnormality, autoimmune diseases, chemo- and radiation-therapies, as well as ovarian surgeries. In unmarried women with severe ovarian dysfunction, fertility preservation is important for future pregnancies. Although oocyte cryopreservation is an established method for fertility preservation, these patients could only preserve a limited number of oocytes even after ovarian hyperstimulation, leading to repeated stimulations to ensure sufficient oocytes to guarantee future pregnancy. To solve this issue, we have recently developed a drug-free in vitro activation (IVA) procedure, which enable us to stimulate early stages of ovarian follicles to develop to the preantral follicle stage. These preantral follicles can respond to the unique protocol of gonadotropin stimulation, resulting in increased number of retrieved oocytes per ovarian stimulation for cryopreservation. The drug-free IVA comprised from the surgical approach and ovarian stimulation. We removed a part of cortex from one or both ovaries from patients under laparoscopic surgery. The ovarian cortical tissues were cut into small cubes to disrupt the Hippo signaling pathway and stimulate the development of early stage follicles. These cubes were grafted orthotropically into remaining ovaries as well as beneath the serosa of both Fallopian tubes. We have already published the surgical procedure of the drug-free IVA and the protocol of subsequent ovarian stimulation, but herein we present the details of laboratory methods required for drug-free IVA.

High-Speed Atomic Force Microscopy of the Structure and Dynamics of Calcite Nanoscale Etch Pits.

Calcite dissolution is initiated by the formation of a nanoscale etch pit followed by step edge propagation and hence strongly influenced by the interactions between surface diffusing ions and step edges. However, such atomic-scale dynamics are mostly inaccessible with current imaging tools. Here, we overcome this limitation by using our recent development of high-speed frequency modulation atomic force microscopy. By visualizing atomic-scale structural changes of the etch pits at the calcite surface in water, we found the existence of mobile and less-mobile surface adsorption layers (SALs) in the etch pits. We also found that some etch pits maintain their size for a long time without expansion, and their step edges are often associated with less-mobile SALs, suggesting their step stabilization effect.

CXCL5-CXCR2 signaling is a senescence-associated secretory phenotype in preimplantation embryos.

Pregnancy rate of women decreases with age due to declining quality of oocytes and embryos. However, there is no established method to improve pregnancy rate in aging women. In this study, we identified a senescence-associated secretory phenotype (SASP) factor partially responsible for the decline in embryo implantation potential. Based on microarray analysis using young and aging human embryos at the same morphological grade, 702 genes showed >fivefold increases in aging human blastocysts. Among these genes, C-X-C motif chemokine 5 (CXCL5) showed 7.7-fold increases in aging human blastocysts. However, no-age-dependent changes in expression of the CXCR2, the cognate receptor for CXCL5, were found. In aging mice, Cxcl5 transcript levels were also increased in oocytes and embryos. Treatment of young mouse embryos with CXCL5 decreased implantation rates, together with increased expression of aging markers (P53, P21, Pai-1, and Il-6). Moreover, CXCL5 treatment suppressed trophoblast outgrowth in young mouse blastocysts. Conversely, suppression of CXCL5-CXCR2 signaling in aging mouse embryos using neutralizing antibodies and a receptor antagonist improved the implantation rate, leading to increases in pregnancy and delivery of normal pups. The gene expression pattern of these embryos was comparable to that in young mouse embryos showing enriched cell proliferation-related pathways. In conclusion, we identified CXCL5 as a SASP factor in human and mouse embryos and suppression of CXCL5-CXCR2 signaling during embryo culture improved pregnancy success in aging mice. Future analysis on CXCL5-CXCR2 signaling suppression in human embryos could be the basis to improve embryo development and pregnancy outcome in middle-aged infertile patients.

Impairment of synaptic development in the hippocampus of diabetic Goto-Kakizaki rats.

Insulin receptor signaling has been shown to regulate essential aspects of CNS function such as synaptic plasticity and neuronal survival. To elucidate its roles during CNS development in vivo, we examined the synaptic and cognitive development of the spontaneously diabetic Goto-Kakizaki (GK) rats in the present study. GK rats are non-obese models of type 2 diabetes established by selective inbreeding of Wistar rats based on impaired glucose tolerance. Though they start exhibiting only moderate hyperglycemia without changes in plasma insulin levels from 3 weeks postnatally, behavioral alterations in the open-field as well as significant impairments in memory retention compared with Wistar rats were observed at 10 weeks and were worsened at 20 weeks. Alterations in insulin receptor signaling and signs of insulin resistance were detected in the GK rat hippocampus at 3 weeks, as early as in other insulin-responsive peripheral tissues. Significant reduction of an excitatory postsynaptic scaffold protein, PSD95, was found at 5w and later in the hippocampus of GK rats due to the absence of a two-fold developmental increase of this protein observed in Wistar control rats between 3 and 20w. In the GK rat hippocampus, NR2A which is a NMDA receptor subunit selectively anchored to PSD95 was also reduced. In contrast, both NR2B and its anchoring protein, SAP102, showed similar developmental profiles in Wistar and GK rats with expression peaks at 2 and 3w. The results suggest that early alterations in insulin receptor signaling in the GK rat hippocampus may affect cognitive performance by suppressing synaptic maturation.

Suppression of hydatidiform molar growth by inhibiting endogenous brain-derived neurotrophic factor/tyrosine kinase B signaling.

Brain-derived neurotrophic factor (BDNF)/tyrosine kinase B (TrkB) receptor signaling promotes trophoblast growth in normal and abnormal pregnancy. It also regulates the growth of malignant trophoblastic, choriocarcinoma cells. However, possible involvement of this signaling system in hydatidiform mole, another major gestational trophoblastic disease, has not been determined. Here, we found the expression of BDNF in syncytiotrophoblasts and its receptor, TrkB, in cytotrophoblasts of hydatidiform mole using real-time RT-PCR and immunoassays. In molar explant cultures, treatment with soluble TrkB ectodomain or a Trk receptor inhibitor K252a inhibited trophoblast outgrowth as well as decreased cytotrophoblast proliferation and cellular viability based on histopathological analyses and glucose metabolism monitoring. These inhibitors also increased apoptosis and caspase-3/7 activities. In an in vivo model of hydatidiform molar growth based on xenotransplantation of molar tissues into kidney capsules of SCID mice, treatment with K252a suppressed molar growth as reflected by decreased trophoblast proliferation and their invasion into mouse kidney, reduced tissue levels of chorionic gonadotropin-ß, and increased apoptosis. Based on PCR array analyses to identify changes in expression profiles of cell cycle- and apoptosis-related genes in cultured molar explants, suppression of endogenous TrkB signaling led to decreases in key cell cycle-stimulatory and checkpoint genes together with the down-regulation of different antiapoptotic genes. Our findings demonstrate the importance of paracrine signaling by the BDNF/TrkB system in the proliferation and survival of molar trophoblasts. Inhibition of BDNF/TrkB signaling could provide a novel medical treatment for hydatidiform mole.