Mechanisms of Ovarian Atresia Induced by Xenobiotic Exposures

The focus of this chapter is the mechanisms of apoptosis that occur during “normal” (physiologically-induced) or “abnormal” (chemical- or pathology-induced) attrition of ovarian oocytes. One of the primary functions of the ovary is development and maturation of oocytes, which occur within a follicular structure. During fetal development of the ovary, primordial germ cells (oogonia) are formed and become oocytes when they stop dividing, and are arrested at the diplotene stage (prophase) of the first meiotic division. At this stage the oocyte is surrounded by a single layer of flattened somatic cells (pre-granulosa cells) and a basement membrane to form primordial follicles (Hirshfield, 1991), the most immature follicular stage of development. As a result, the lifetime supply of oocytes is set at the time of birth, and is irreplaceable. Association of the granulosa cells with the oocyte is critical for maintenance of oocyte viability and follicle development (Buccione et al., 1990). Development and progression of a recruited follicle also requires the appropriate expression of numerous factors, including critical members of the transforming growth factor β superfamily, such as growth differentiation factor 9 (GDF9) and bone morphogenic protein (BMP15) (Paulini and Melo 2011). Characterization of GDF9 function has a demonstrated a required role in promoting somatic cells of the follicle to undergo mitosis and initiates paracrine signaling between the oocyte and the follicular cells surrounding it (Carabatsos et al. 1998; Hreinsson et al. 2002; Nilsson and Skinner 2002). The impaired fertility in GDF9 mice appears to primarily be a result of loss of function in somatic cells since oocytes of GDF knockout mice remain capable of undergoing in vitro maturation and progressing to metaphase II of meiosis (Carabatsos et al. 1998)

Static and dynamic XY-like short-range order in a frustrated magnet with exchange disorder

A single crystal of the Co2+ based pyrochlore NaCaCo2F7 was studied by inelastic neutron scattering. This frustrated magnet with quenched exchange disorder remains in a strongly correlated paramagnetic state down to one 60th of the Curie-Weiss temperature. Below T_f = 2.4 K, diffuse elastic scattering develops and comprises 30 +/- 10% of the total magnetic scattering, as expected for J_{eff} = 1/2 moments frozen on a time scale that exceeds \hbar/\delta E=3.8 ps. The diffuse scattering is consistent with short range XY antiferromagnetism with a correlation length of 16 \AA. The momentum (Q) dependence of the inelastic intensity indicates relaxing XY-like antiferromagnetic clusters at energies below ~ 5.5 meV, and collinear antiferromagnetic fluctuations above this energy. The relevant XY configurations form a continuous manifold of symmetry-related states. Contrary to well-known models that produce this continuous manifold, order-by-disorder does not select an ordered state in NaCaCo2F7 despite evidence for weak (~12 %) exchange disorder. Instead, NaCaCo2F7 freezes into short range ordered clusters that span this manifold.Comment: 9 pages, 9 figures. This updated version features modified figures and some new discussio

DND1 Expression and Function in the Porcine Ovary, Oocyte and Embryo

DND1 (dead end homolog 1), belonging to the RNA binding protein family, can impact miRNA:mRNA functional pathway and in turn may contribute to maintaining normal oocyte growth and quality as well as embryo development following fertilization. To characterize DND1 in pig maturing oocytes and cumulus cells, and early embryos, we examined DND1 mRNA and protein expression using quantitative RT-PCR, Western blot and immunostaining. We found: (1) DND1 protein is expressed during pig follicle development; (2) DND1 is dynamically expressed at both mRNA and protein level in the maturing oocyte and early in vitro fertilized embryos; (3) DND1 mRNA is expressed in cumulus cells surrounding the maturing oocyte; and (4) DND1 protein is localized in the cytoplasm of pig maturing oocytes and early embryos. Our work provides useful data for functional study of DND1 proteins in female gametogenesis and developing embryos, which will benefit animal reproduction health and provides foundational knowledge for improving swine reproductive efficiency

Effects of Sample Disturbance and Consolidation Procedures on Cyclic Strengths of Intermediate Soils

Sampling and testing of soils to measure engineering properties, such as monotonic and cyclic undrained shear strengths, requires an understanding of the potential effects of sampling disturbance and the selection of appropriate laboratory testing procedures. For clays, past research has provided insights on how sampling methods and laboratory testing procedures can be used in practice to assess and minimize sample disturbance effects. For sands, past research has shown that conventional tube sampling techniques cause excessive disturbance to the soil fabric, such that subsequent measurement of monotonic or cyclic strengths can be greatly in error and misleading. For intermediate soils, the effects of disturbance and consolidation procedures on monotonic and cyclic strengths are not well understood. In the present study, a test protocol was developed to assess the effects that disturbance during sample extrusion, trimming, and mounting have on subsequent measurements of compressibility, monotonic undrained strength, and cyclic undrained strength. Detailed laboratory tests were performed on tube samples from deposits of low-plasticity silty clay, for which conventional sampling and testing were expected to work reasonably well, and low-plasticity clayey sand, for which the effects of sample disturbance were of primary concern. Test results using this protocol for these two soils are presented and discussed

Attenuation of neural responses in primary visual cortex during the attentional blink

Information-processing bottlenecks are characteristic of many cognitive and neural systems. One such bottleneck is revealed by tasks in which rapidly successive stimulus events must be reported. Here, observers missed the second of two visual targets if it occurred within 700 ms of the first [an "attentional blink" (AB)], even though this second target could be reported accurately when the first item was ignored. Isolating neural responses to such rapid events has proven difficult because current magnetic resonance imaging methods rely on relatively sluggish changes in the brain's physiological response to sensory inputs. Here, we overcame this limitation by presenting successive visual targets at different spatial locations, thereby exploiting the retinotopic organization of early cortical visual areas to distinguish neural activity associated with successive target events. We show that neural activity in primary visual cortex is significantly modulated during the AB, and that this activity mirrors behavioral measures of target identification accuracy. The findings suggest that the neural signature of perceptual suppression during processing of rapidly successive stimuli is evident at the earliest stages of cortical sensory processing

Visual-motor interactions during action observation are shaped by cognitive context

Interactions between the visual system and the motor system during action observation are important for functions such as imitation and action understanding. Here, we asked whether such processes might be influenced by the cognitive context in which actions are performed. We recorded ERPs in a delayed go/no-go task known to induce bidirectional interference between the motor system and the visual system (visuomotor interference). Static images of hand gestures were presented as go stimuli after participants had planned either a matching (congruent) or nonmatching (incongruent) action. Participants performed the identical task in two different cognitive contexts: In one, they focused on the visual image of the hand gesture shown as the go stimulus (image context), whereas in the other, they focused on the hand gesture they performed (action context). We analyzed the N170 elicited by the go stimulus to test the influence of action plans on action observation (motor-to-visual priming). We also analyzed movement-related activity following the go stimulus to examine the influence of action observation on action planning (visual-to-motor priming). Strikingly, the context manipulation reversed the direction of the priming effects: We found stronger motor-to-visual priming in the action context compared with the image context and stronger visual-to-motor priming in the image context compared with the action context. Taken together, our findings indicate that neural interactions between motor and visual processes for executed and observed actions can change depending on task demands and are sensitive to top-down control according to the context

Heat Stress during Pig Oocyte In Vitro Maturation Impacts Embryonic Development and Gene Expression

Gene expression of heat stressed oocytes matured in vitro was evaluated for potential markers which could be used to characterize the effects of heat stress on developing oocytes in the pig. Three heat stress scenarios were administered during in vitro oocyte maturation. Heat stressed oocytes had reduced maturation rates, decreased developmental competency, and altered expression of heat stress and developmental competency markers

Real-space investigation of short-range magnetic correlations in fluoride pyrochlores NaCaCo2_2F7_7 and NaSrCo2_2F7_7 with magnetic pair distribution function analysis

We present time-of-flight neutron total scattering and polarized neutron scattering measurements of the magnetically frustrated compounds NaCaCo$_2$F$_7$ and NaSrCo$_2$F$_7$, which belong to a class of recently discovered pyrochlore compounds based on transition metals and fluorine. The magnetic pair distribution function (mPDF) technique is used to analyze and model the total scattering data in real space. We find that a previously-proposed model of short-range XY-like correlations with a length scale of 10-15 \AA, combined with nearest-neighbor collinear antiferromagnetic correlations, accurately describes the mPDF data at low temperature, confirming the magnetic ground state in these materials. This model is further verified by the polarized neutron scattering data. From an analysis of the temperature dependence of the mPDF and polarized neutron scattering data, we find that short-range correlations persist on the nearest-neighbor length scale up to 200 K, approximately two orders of magnitude higher than the spin freezing temperatures of these compounds. These results highlight the opportunity presented by these new pyrochlore compounds to study the effects of geometric frustration at relatively high temperatures, while also advancing the mPDF technique and providing a novel opportunity to investigate a genuinely short-range-ordered magnetic ground state directly in real space

Endometrial caspase 1 and interleukin-18 expression during the estrous cycle and peri-implantation period of porcine pregnancy and response to early exogenous estrogen administration

<p>Abstract</p> <p>Background</p> <p>The role for endometrial secretion of cytokines during the establishment of pregnancy in a number of mammals is well established. The current study determined endometrial expression of caspase 1 (CASP1) and interleukin-18 (IL18) during the estrous cycle and early pregnancy, and following early estrogen administration, which induces conceptus loss during early development in pigs.</p> <p>Methods</p> <p>Gilts were hysterectomized on either D 0, 5, 10, 12, 15 and 18 of the estrous cycle, or D 10, 12, 15 or 18 of pregnancy. The abundance of endometrial CASP1 mRNA was unaffected by day of the estrous cycle, however there was a 6 and 10-fold increase in expression on D 15 and 18 of pregnancy. Endometrial expression of IL18 mRNA increased 5-fold between D 10 to 18 in cyclic and pregnant gilts. Total recoverable IL18 in uterine flushings was greater in pregnant compared to cyclic gilts on D 15 and 18.</p> <p>In the second experiment, mated gilts were treated with either corn oil (CO) or estrogen (E) on D 9 and 10 and hysterectomized on either D 10, 12, 13, 15 or 17 of pregnancy. The current study localizes the presence of CASP1 to the epithelial layer of the endometrium for the first time. Further, a day × treatment interaction was detected for endometrial CASP1 mRNA and protein abundance as E stimulated an earlier increase on D 13 compared to CO gilts. Although IL18 mRNA expression remained unaltered from the E treatment, protein abundance was significantly attenuated on D 15 and 18 in response to E treatment.</p> <p>Conclusions</p> <p>Endometrial expression of CASP1 and IL18 is associated with establishment of pregnancy in pigs. Alteration of CASP1 and IL18 following premature exposure of the uterus to estrogen during early pregnancy may contribute to conceptus loss between Days 15 to 18 of pregnancy.</p