The biogeography of shallow-water macrofauna at Heard Island

Collections of 23 macroinvertebrate taxa associated with Durvillaea antarctica holdfasts and 58 invertebrate taxa associated with artificial substrata collectors are described from shallow-water and intertidal habitats at Heard Island. The fauna sampled possessed strong biogeographic affinities with the Kerguelen Island fauna and, to a slightly lesser extent, the fauna recorded at Macquarie Island but negligible affinity with the Antarctic. Experiments involving the offshore tethering of D. antarctica holdfasts indicated that epifaunal invertebrates rapidly abandoned detached holdfasts, but that the few species surviving after one day could probably survive long periods adrift

The cytotrophoblastic shell and complications of pregnancy

Many complications of pregnancy have their pathophysiological roots in the early stages of placentation. Impaired trophoblast invasion and deficient remodelling of the maternal spiral arteries are a common feature. While malperfusion of the placenta may underpin cases of fetal growth restriction and early-onset pre-eclampsia, the mechanistic links to spontaneous miscarriage, pre-term labour and premature rupture of the membranes are less obvious. Here, we speculate that formation of a well-developed cytotrophoblastic shell at the maternal-fetal interface is crucial for pregnancy success. Initially, extravillous trophoblast cells differentiate from the outer layer of the shell in contact with the endometrium. Impaired development may thus contribute to reduced invasion and deficient remodelling. In addition, the extent of the shell influences the timing and spatial configuration of onset of the maternal arterial circulation. A thin and fragmentary shell results in premature and disorganised onset, leading to spontaneous miscarriage. In less severe cases it may predispose to haemorrhage at the interface and formation of intrauterine haematomas. If pregnancy continues, these haematomas may act as a source of oxidative stress, promoting senescence and weakening of the membranes, and stimulating inflammation in the uterine wall and premature contractions. Formation of the shell is dependent on proliferation of cytotrophoblast progenitor cells during the first weeks after implantation, when the developing placenta is supported by histotrophic nutrition from endometrial glands. Hence, we propose the fitness of the endometrium prior to conception, and the peri-conceptional dialogue between the endometrium and the trophoblast is critical for avoidance of later complications of pregnancy.The Global Pregnancy Collaboration is part of the Pre-eclampsia-Eclampsia Monitoring, Prevention & Treatment (PRE-EMPT) initiative funded by the University of British Columbia, a grantee of the Bill & Melinda Gates Foundation

Mitochondrial - Endoplasmic reticulum interactions in the trophoblast: Stress and senescence.

Placental stress has been implicated in the pathophysiology of complications of pregnancy, including growth restriction and pre-eclampsia. Initially, attention focused on oxidative stress, but recently mitochondrial and endoplasmic reticulum stress have been identified. Complex molecular interactions exist among these different forms of stress, making it unlikely that any occurs in isolation. In part, this is due to close physiological connections between the two organelles principally involved, mitochondria and the endoplasmic reticulum (ER), mediated through Ca2+ signalling. Here, we review the involvement of the mitochondria-ER unit in the generation of stress within the trophoblast, and consider consequences for obstetric outcome. Mild stress may induce adaptive responses, including upregulation of antioxidant defences and autophagy, while moderate levels may affect stem cell behaviour and reduce cell proliferation, contributing to the growth-restricted phenotype. High levels of stress can stimulate release of pro-inflammatory cytokines and anti-angiogenic factors, increasing the risk of pre-eclampsia. In addition, chronic stress may promote senescence of the trophoblast, which in other cell types leads to a pro-inflammatory senescence-associated secretory phenotype. Evidence from rodents suggests that a degree of trophoblastic stress develops with increasing gestational age in normal pregnancies. The increase in maternal concentrations of soluble fms-like tyrosine kinase-1 (sFlt-1) and reduction in placental growth factor (PlGF) suggest the same may occur in the human, starting around 30 weeks of pregnancy. Placental malperfusion, or co-existing maternal conditions, such as diabetes, will exacerbate that stress. Amelioration of trophoblastic stress should remain a research priority, but will be difficult due to the complexity of the molecular pathways involved.The authors thank all their colleagues and collaborators who have contributed to their studies cited here. GJB gratefully acknowledges the support of the Wellcome Trust (069027/Z/02/Z and 084804/2/08/Z), the MRC and Tommy’s; AJM thanks the Research Councils UK, Action Medical Research (SP4545) and the WYNG Foundation of Hong Kong.This is the author accepted manuscript. The final version is available from Elsevier via http://dx.doi.org/10.1016/j.placenta.2016.04.00

Placental Implantation Disorders

Primary disorders of placental implantation have immediate consequences for the outcome of a pregnancy. These disorders have been known to clinical science for more than a century, but have been relatively rare. Recent epidemiologic obstetric data have indicated that the rise in their incidence over the last 2 decades has been iatrogenic in origin. In particular, the rising numbers of pregnancies resulting from in vitro fertilization (IVF) and the increased use of caesarean section for delivery have been associated with higher frequencies of previa implantation, accreta placentation, abnormal placental shapes, and velamentous cord insertion. These disorders often occur together

Different epigenetic states define syncytiotrophoblast and cytotrophoblast nuclei in the trophoblast of the human placenta.

INTRODUCTION: The syncytiotrophoblast (STB) epithelial covering of the villous tree in the human placenta is a multi-nucleated syncytium that is sustained by continuous incorporation of differentiating cytotrophoblast (CTB) cells. STB nuclei display a variety of morphologies, but are generally more condensed in comparison to CTB nuclei. Here, we consider whether this condensation is a feature of epigenetic regulation of chromatin structure. METHODS: Semi-quantitative immunohistochemical investigations of a panel of histone modifications were performed to determine the relative proportions in CTB and STB nuclear populations. We also investigated the patterns of DNA methylation and distribution of DNA methyltransferases enzymes in these populations. RESULTS: Unexpectedly DNA methylation, and H3K9me3 and H3K27me3, which are modifications associated with heterochromatin, are present at lower levels in STB nuclei compared to CTB, despite the intensive condensation in the former nuclear population and the progenitor state of the latter. By contrast, STB nuclei are enriched for H4K20me3, which is also associated with repressive states. 5'hydroxymethylcytosine immunoreactivity is higher in STB, with intense staining observed in the highly condensed nuclei within syncytial knots. DISCUSSION: Cell-type specific epigenetic states exist within the trophoblast populations potentially regulating their different functions and developmental properties and suggesting non-canonical epigenetic states associated with the properties of these cells.This work was funded by a studentship from the Anatomical Society of Great Britain and Ireland. The study was also supported by the Centre for Trophoblast Research.This is the accepted manuscript. The final version is available at http://www.sciencedirect.com/science/article/pii/S0143400415009248

A simple particle-size distribution model for granular materials

© 2018, Canadian Science Publishing. All rights reserved. Particle-size distribution (PSD) is a fundamental soil property that plays an important role in soil classification and soil hydromechanical behaviour. A continuous mathematical model representing the PSD curve facilitates the quantification of particle breakage, which often takes place when granular soils are compressed or sheared. This paper proposes a simple and continuous PSD model for granular soils involving particle breakage. The model has two parameters and is able to represent different types of continuous PSD curves. It is found that one model parameter is closely related to the coefficient of nonuniformity (Cu) and the coefficient of curvature (Cc), while the other represents a characteristic particle diameter. A database of 53 granular soils with 154 varying PSD curves is analyzed to evaluate the performance of the proposed PSD model, as well as that of three other PSD models in the literature. The results show that the proposed model has improved overall performance and captures the typical trends in PSD evolution during particle breakage. In addition, the proposed model is also used for assessing the internal stability of 27 widely graded soils

Calculating the random guess scores of multiple-response and matching test items

For achievement tests, the guess score is often used as a baseline for the lowest possible grade for score to grade transformations and setting the cut scores. For test item types such as multiple-response, matching and drag-and-drop, determin-ing the guess score requires more elaborate calculations than the more straight-forward calculation of the guess score for True-False and multiple-choice test item formats. For various variants of multiple-response and matching types with respect to dichotomous and polytomous scoring, methods for determining the guess score are presented and illustrated with practical applications. The implica-tions for theory and practice are discussed

Endoplasmic reticulum stress is induced in the human placenta during labour.

Placental endoplasmic reticulum (ER) stress has been postulated in the pathophysiology of pre-eclampsia (PE) and intrauterine growth restriction (IUGR), but its activation remains elusive. Oxidative stress induced by ischaemia/hypoxia-reoxygenation activates ER stress in vitro. Here, we explored whether exposure to labour represents an in vivo model for the study of acute placental ER stress. ER stress markers, GRP78, P-eIF2α and XBP-1, were significantly higher in laboured placentas than in Caesarean-delivered controls localised mainly in the syncytiotrophoblast. The similarities to changes observed in PE/IUGR placentas suggest exposure to labour can be used to investigate induction of ER stress in pathological placentas.This study was funded by the Wellcome Trust (Grant No. 084804/2/08/Z) in UK and Ter Meulen Fund, Royal Netherlands Academy of Arts and Sciences in Netherlands.This is the final published version. It originally appeared online at http://www.sciencedirect.com/science/article/pii/S0143400414008340#

Villous Tree Model with Active Contractions for Estimating Blood Flow Conditions in the Human Placenta

$\textit{Background:}$ In the human placenta, maternal and fetal bloods exchange substances through the surface of the villous trees: the fetal blood circulates in the villous trees, around which the maternal blood circulates. The blood flows directly influence fetal growth. Stem villi, the main supports of the villous tree, have contractile cells along the axes, whose contractions are expected to influence the blood circulations in the placenta. The displacement is neither measurable nor predictable while non-invasive measurements such as umbilical Doppler waveforms are helpful to predict the histological changes of the villous trees and vascularization in the placenta. $\textit{Objective:}$ The displacement caused by the contraction of the villous tree is necessary to predict the blood flows in the placenta. Hence, a computational villous tree model, which actively contracts, was developed in this study. $\textit{Method:}$ The villous tree model was based on the previous reports: shear moduli of the human placenta; branching patterns in the stem villi. The displacement pattern in the placenta was estimated by the computational model when the shear elastic moduli were changed. $\textit{Results:}$ The results show that the displacement caused by the contraction was influenced by the shear elastic moduli, but kept useful for the blood flows in the placenta. The characteristics agreed with the robustness of the blood flows in the placenta. $\textit{Conclusion:}$ The villous tree model, which actively contracts, was developed in this study. The combination of this computational model and noninvasive measurements will be useful to evaluate the condition of the placenta