EQUINE CONCEPTUS DEVELOPMENT – A MINI REVIEW

Many aspects of early embryonic development in the horse are unusual or unique; this is of scientific interest and, in some cases, considerable practical significance. During early development the number of different cell types increases rapidly and the organization of these increasingly differentiated cells becomes increasingly intricate as a result of various inter-related processes that occur step-wise or simultaneously in different parts of the conceptus (i.e., the embryo proper and its associated membranes and fluid).  Equine conceptus development is of practical interest for many reasons. Most significantly, following a high rate of successful fertilization (71-96%) (Ball, 1988), as many as 30-40% of developing embryos fail to survive beyond the first two weeks of gestation (Ball, 1988), the time at which gastrulation begins. Indeed, despite considerable progress in the development of treatments for common causes of sub-fertility and of assisted reproductive techniques to enhance reproductive efficiency, the need to monitor and rebreed mares that lose a pregnancy or the failure to produce a foal, remain sources of considerable economic loss to the equine breeding industry. Of course, the potential causes of early embryonic death are numerous and varied (e.g. persistent mating induced endometritis, endometrial gland insufficiency, cervical incompetence, corpus luteum (CL) failure, chromosomal, genetic and other unknown factors (LeBlanc, 2004). However, the problem is especially acute in aged mares with a history of poor fertility in which the incidence of embryonic loss between days 2 and 14 after ovulation has been reported to reach 62-73%, and in which embryonic death is due primarily to embryonic defects rather than to uterine pathology (Ball et al., 1989; Carnevale & Ginther, 1995; Ball, 2000).

pH-dependent effects of procaine on equine gamete activation

Procaine directly triggers pH-dependent cytokinesis in equine oocytes and induces hypermotility in stallion spermatozoa, an important event during capacitation. However, procaine-induced hyperactivated motility is abolished when sperm is washed to remove the procaine prior to sperm-oocyte co-incubation. To understand how procaine exerts its effects, the external Ca2+ and Na+ and weak base activity dependency of procaine-induced hyperactivation in stallion spermatozoa was assessed using computer-assisted sperm analysis. Percoll-washed stallion spermatozoa exposed to Ca2+-depleted (+2 mM EGTA) procaine-supplemented capacitating medium (CM) still demonstrated hyperactivated motility, whereas CM without NaCl or Na+ did not. Both procaine and NH4Cl, another weak base, were shown to trigger a cytoplasmic pH increase (BCECF-acetoxymethyl (AM)), which is primarily induced by a pH rise in acidic cell organelles (Lysosensor green dnd-189), accompanied by hypermotility in stallion sperm. As for procaine, 25 mM NH4Cl also induced oocyte cytokinesis. Interestingly, hyperactivated motility was reliably induced by 2.5-10 mM procaine, whereas a significant cytoplasmic cAMP increase and tail-associated protein tyrosine phosphorylation were only observed at 10 mM. Moreover, 25 mM NH4Cl did not support the latter capacitation characteristics. Additionally, cAMP levels were more than 10x higher in boar than stallion sperm incubated under similar capacitating conditions. Finally, stallion sperm preincubated with 10 mM procaine did not fertilize equine oocytes. In conclusion, 10 mM procaine causes a cytoplasmic and acidic sperm cell organelle pH rise that simultaneously induces hyperactivated motility, increased levels of cAMP and tail-associated protein tyrosine phosphorylation in stallion spermatozoa. However, procaine-induced hypermotility is independent of the cAMP/protein tyrosine phosphorylation pathway

Matsuo algebras in characteristic 2

We extend the theory of Matsuo algebras, which are certain non-associative algebras related to 3-transposition groups, to characteristic 2. Instead of idempotent elements associated to points in the corresponding Fischer space, our algebras are now generated by nilpotent elements associated to lines. For many 3-transposition groups, this still gives rise to a $\mathbb{Z}/2\mathbb{Z}$-graded fusion law, and we provide a complete classification of when this occurs. In one particular small case, arising from the 3-transposition group $\operatorname{Sym}(4)$, the fusion law is even stronger, and the resulting Miyamoto group is an algebraic group $\mathbb{G}_a^2 \rtimes \mathbb{G}_m$.Comment: 19 page

MATERNAL RECOGNITION OF PREGNANCY IN THE MARE – A MINI REVIEW

A number of features of early embryonic development in equids are unusual or unique; these appear to include the critical but poorly understood mechanism(s) responsible for the ‘maternal recognition of pregnancy’. Maternal recognition of pregnancy is the physiological process by which a developing conceptus signals it presence to the maternal organism to prolong the lifespan of the primary corpus luteum (CL) and thereby ensure the continued supply of progesterone that is essential for embryonic survival and development.  However, it is not yet clear what the primary conceptus signal to ensure CL prolongation in the horse is, and while a number of potential contributors to maternal recognition and the establishment of pregnancy have been proposed, none have been able to satisfactorily fulfill the criteria required of an intrauterine luteostatic or antiluteolytic factor. On the other hand, it is generally accepted that maternal recognition of pregnancy is of critical importance and that failure to either send or receive the signal appropriately is likely to lead to early embryonic death. Indeed, pregnancy loss at or soon after the expected time of maternal pregnancy recognition (days 10-16 of gestation) is a common, but unpredictable (and therefore difficult to prevent), occurrence in clinical practice and a considerable source of financial loss to the breeding industry

Особливості побудови соціоеконометричних моделей на змішаному факторному просторі

Подано методологічні підходи до побудови, ідентифікації та змістовної інтерпретації економетричних моделей взаємозв'язків на факторному просторі, що поєднує ознаки, виражені як метричною, або порядковою, так і дихотомічною, або номінальною, шкалами. Розглянуто особливості використання алгоритмів регресійного аналізу для побудови моделей такого типу. На фактичному матеріалі наведено варіанти апробації запропонованих підходів.Представлены методологические подходы к построению, идентификации и содержательной интерпретации эконометрических моделей взаимосвязей на факторном пространстве, которое объединяет признаки, выраженные как метрической, или порядковой, так и дихотомической, или номинальной, шкалами. Рассмотрены особенности использования алгоритмов регрессионного анализа для построения моделей такого типа. На фактическом материале представлены варианты апробации предложенных подходов.The paper presents methodological approaches to construction, identification and substantial interpretation of econometric models of interrelations in the factorial spacee. The factorial space includes the factors presented both by metric or ordinal, and dichotomizing or nominal scales. The features of regression analysis algorithms use for constructing of the above models are considered. The variants of approbation of the offered approaches are presented using the real material

Ohio Farm Household Longitudinal Study: 1986 Summary Results

ESO 1401-1409 inclusive