Математичне моделювання стаціонарного теплопереносу в процесах випікання тонких плоских тістових заготовок

Розглянуто математичну модель стаціонарного теплопереносу в процесах випікання тонких плоских тістових заготовок. Проведено числове моделювання і аналіз стаціонарних температурних полів для нагрівальної плити і заготовки з точки зору забезпечення більшої рівномірності нагріву за різними напрямками із врахуванням частотних характеристик нагрівання.Mathematical model of stationary heat transfer for baking processes of thin flat pastry blanks are considered. Numerical modeling and analyze of stationary temperature fields for hot plane and blank are conducted with taking into account condition of regular heating for different directions and heating frequencies characteristics

Developmental changes in expression of pluripotent genes in early equine embryos.

Genes involved in maintaining pluripotency have potential use in establishing cell lines for regenerative medicine. However, the genes differ subtly between species, and are poorly described in the horse. In this study we examined changes in expression of pluripotency-associated genes in horse embryos during blastocyst formation. Twenty-one grade 1–2 embryos where recovered from mares by uterine lavage on Day 6–7 after ovulation. Embryos were classified by developmental stage (morula, early or expanded blastocyst: n = 5, 7 and 9, respectively) and their diameter measured by micrometer, before being snap frozen. Subsequently, mRNA from individual embryos was extracted, DNAse-treated and synthesized into cDNA using an AllPrep Mini Kit and Superscript III Reverse Transcriptase (Qiagen, Venlo, and Invitrogen, Breda respectively, the Netherlands). Equine-specific intron-spanning/overlapping primers were designed using PerlPrimer v1.1.14 by BLAST searching the NCBI horse genome for 5 genes associated with pluripotency in other species (octamer binding protein OCT4, transcription factor NANOG, developmental pluripotency-associated DPPA4, growth and differentiation factor GDF3 and telomerase reverse transcriptase TERT) and 2 reference genes (signal recognition particle SRP14 and phosphoglycerate kinase PGK1). Relative gene expression was then examined by quantitative PCR using an iQ5 RT PCR Detection System (BioRad, Veenendaal, the Netherlands). Relationships were tested by Pearson correlations and differences between developmental stages were tested by ANCOVA. Embryos ranged in diameter from 126 to 680 μm. As expected, absolute expression of all pluripotency markers increased with increasing embryo diameter (P = 0.000; R = 0.93, 0.92, 0.88, 0.86 and 0.76 for NANOG, DPPA4, GDF3, OCT4 and TERT, respectively). After normalization with SRP14 and PGK1, significant negative correlations with embryo diameter were apparent for OCT4, NANOG and DPPA4 (P < 0.001; R = –0.73, –0.69 and –0.53, respectively). Moreover, all 5 pluripotency genes were down-regulated as embryonic development progressed (P < 0.05), although the time-course differed between genes. The DPPA4 and OCT4 expression decreased significantly at both the morula-early blastocyst and early-expanded blastocyst transitions, whereas NANOG expression only decreased significantly between the early-expanded blastocyst stages and GDF3 and TERT expression only between the morula-early blastocyst stages. Down-regulation of pluripotent gene expression during early development is consistent with increased cohorts of cells differentiating into trophectoderm and primitive endoderm, leaving an ever decreasing proportion of pluripotent cells in the inner cell mass. Furthermore, the different time courses of down-regulation may reflect different roles of the examined genes in developmental processes. For example, early and continued down-regulation of OCT4 is consistent with a role in differentiation between ICM and trophectoderm, whereas the slightly later onset of NANOG down-regulation better fits a role in determining between pluripotent epiblast and primitive endoderm, as described in other species

Морфологічні аспекти реакції тиротропів аденогіповіза, як наслідок хронічної інтоксикації малими дозами пестициду 2,4 Д

В работе представлены результаты исследований структурно-функциональных изменений тиротропных клеток аденогипофиза в условиях пестицидной интоксикации различной длительности.In this work we prove the presente the results of structural estimation of the functional state of the adenohypophysis in different periods of pesticide intoxication increase

Regenerative Medicine : Taming the Chimaera

In this issue of Stem Cell Reports, Hamanaka et al. (2018) describe the generation of chimeric mice with all vascular endothelial cells derived from pluripotent stem cells. This approach is desirable to prevent immune rejection when human stem cells are combined with animal embryos to grow human organs in animals

Stay on the road: from germ cell specification to gonadal colonization in mammals

The founder cells of the gametes are primordial germ cells (PGCs). In mammals, PGCs are specified early during embryonic development, at the boundary between embryonic and extraembryonic tissue, long before their later residences, the gonads, have developed. Despite the differences in form and behaviour when differentiated into oocytes or sperm cells, in the period between specification and gonadal colonization, male and female PGCs are morphologically indistinct and largely regulated by similar mechanisms. Here, we compare different modes and mechanisms that lead to the formation of PGCs, putting in context protocols that are in place to differentiate both human and mouse pluripotent stem cells into PGC-like cells. In addition, we review important aspects of the migration of PGCs to the gonadal ridges, where they undergo further sex-specific differentiation. Defects in migration need to be effectively corrected, as misplaced PGCs can become tumorigenic. Concluding, a combination of in vivo studies and the development of adequate innovative in vitro models, ensuring both robustness and standardization, are providing us with the tools for a greater understanding of the first steps of gametogenesis and to develop disease models to study the origin of germ cell tumours.This article is part of the theme issue 'Extraembryonic tissues: exploring concepts, definitions and functions across the animal kingdom'

Stay on the road: from germ cell specification to gonadal colonization in mammals

The founder cells of the gametes are primordial germ cells (PGCs). In mammals, PGCs are specified early during embryonic development, at the boundary between embryonic and extraembryonic tissue, long before their later residences, the gonads, have developed. Despite the differences in form and behaviour when differentiated into oocytes or sperm cells, in the period between specification and gonadal colonization, male and female PGCs are morphologically indistinct and largely regulated by similar mechanisms. Here, we compare different modes and mechanisms that lead to the formation of PGCs, putting in context protocols that are in place to differentiate both human and mouse pluripotent stem cells into PGC-like cells. In addition, we review important aspects of the migration of PGCs to the gonadal ridges, where they undergo further sex-specific differentiation. Defects in migration need to be effectively corrected, as misplaced PGCs can become tumorigenic. Concluding, a combination of in vivo studies and the development of adequate innovative in vitro models, ensuring both robustness and standardization, are providing us with the tools for a greater understanding of the first steps of gametogenesis and to develop disease models to study the origin of germ cell tumours.This article is part of the theme issue 'Extraembryonic tissues: exploring concepts, definitions and functions across the animal kingdom'.Stem cells & developmental biolog

On the formation of germ cells: The good, the bad and the ugly

Mammalian germ cells are powerful cells, the only ones that transmit information to the next generation ensuring the continuation of the species. But "with great power, comes great responsibility", meaning that germ cells are only a few steps away from turning carcinogenic. Despite recent advances little is known about germ cell formation in mammals, predominantly because of the inaccessibility of these cells. Moreover, it is difficult to pin down what in essence is characteristic of a germ cell, as germ cells keep changing place, morphology, expression markers and epigenetic identity. Formation of (primordial) germ cells in primate ES cell cultures would therefore be helpful to identify molecular signalling pathways associated with germ cell differentiation and to study epigenetic changes in germ cells. In addition, the in vitro derivation of functional germ cells from ES cells could be used in combination with therapeutic cloning to generate patient-specific ES cell lines, and can have applications in animal breeding. In this review we present the state-of-the-art on how mouse and human germ cells are formed in vivo (the good), we discuss the link between germ cells, pluripotency and germ cell tumours (the bad) and show that despite continuous progress in trying to differentiate germ cells in vitro (the ugly) the generation of functional germ cells is still a real challenge.Stem cells & developmental biolog

STEM CELLS Cloning human embryos

Stem cells & developmental biolog