Function of the microcirculatory system during the long-term regression of the early stages of atherogenesis

Lipid metabolism, intestinal mesentery microcirculatory bed (MCB) and erythrocyte (E) morphology in arterial and venous blood were studied in rabbits with experimental atherosclerosis (the model of N. N. Anichkov) and its spontaneous regression. The interrelation was determined between lipid metabolism (LM), MCB structural and functional disorders and anomalous E form appearance, and to a lesser extent the atheromatosis of the aorta. Microcirculatory (MC) disorders disappeared 12 months later in the regression of the early stages of atherogenesis (after 2 months of diet). The generalized character of MC disorders in LM suggests the existence of a trend towards MC reconstitution in prolonged regression in different organs and tissues. Thus, LM correction at the early stages of the pathological process can be accompanied by the disappearance of MC disorders, which seems important for the prevention of atherosclerosis.     

Neurospecific and neuron-specific enolase levels in human nerve tissue at early stages of embryogenesis

Neurospecific and neuro-nonspecific isozymes of glycolytic enzyme enolase known to be molecular markers of neuronal and glial cells respectively were isolated from human brain. Using immunoenzyme assay, the content of these proteins was measured in the brain of 7-13-week human embryos and adult subjects. The content of both isoenzymes gradually increases attaining constant level in 10-13-week embryos. Relative content of neuro-nonspecific enolase in the brain of 10-13-week embryos is 1 1/2 times higher than that in adults, whereas the content of neurospecific enolase amounts only to 2% of its level in the adult brain.     

Alisma embryogenesis: The development and ultrastructure of the suspensor

Summary The development of the suspensor (consisting of a basal cell and a few chalazal cells) inAlisma plantagoaquatica andA. lanceolatum was investigated using cytochemical methods, light and electron microscopy. The basal cell becomes differentiated during the first three days of embryo development. As a result of endopolyploidization the volume of the nucleus rapidly increases, as does the quantity of chromatin it contains and the size of the nucleolus. As basal cell grows, its cytoplasm increases in volume and the number of organelles increase, and wall ingrowths begin to form on the walls at the micropylar pole of the cell. The full development and functioning of the suspensor occurs during the next three days. The enormous basal cell then attains its maximum degree of differentiation: its nucleus reaches a ploidy of 256n or 512n, the micropylar transfer wall is fully developed, as is the cytoplasm, rich in proteins, ribonucleic acids (RNA) and organelles, particularly dictyosomes and long cisternae of the rough endoplasmic reticulum. The chalazal suspensor cells joining the embryo proper to the basal cell also become differentiated. In the seven-day embryo the suspensor begins to degenerate which coincides with the cellularization of the endosperm at the micropylar pole of the embryo sac. The senescence of the suspensor involves the degradation of the nucleus, increasing cytoplasmic vacuolization, and a distinct decrease in protein and RNA content, first in the basal cell, then in the chalazal suspensor cells. Analysis of the development and ultrastructure of the basal suspensor cell suggests that it plays the role of an active metabolic transfer cell, translocating nutrients from the maternal tissues via the chalazal suspensor cells to the growing embryo proper.     

Patterns of mechanical stress at the successive stages of early development of frog]

The immediate relaxation deformations have been studied in the embryonic frog tissues from the late blastula stage till the early tail bud stage. As a result, the maps of mechanical stresses were constructed which were characterized by the existence of distinct tension-lines dissecting the embryonic tissues (cross-lines). A few discrete moments of development were established when new cross-lines formed or the previous ones disappeared; they are separated by the topologically invariant periods of development. The cross-lines play an important role in morphogenesis in that they determine the ways of active cell migration and trace the boundaries between different anlages. The orientation of the cross-lines coincides, as a rule, with the direction of predominant tension of tissues during the preceding topologically invariant period of development.     

Clarifying tetrapod embryogenesis by a dorso-ventral analysis of the tissue flows during early stages of chicken development

The formation of an animal body remains largely a mystery. It is still not clear whether anything like an organization plan or an "archetype" as coined by Darwin himself, actually exists, or whether animals are organized by a succession of stop-and-go genetic, non-linear, instructions with no global pattern. Nevertheless, it was recognized long ago that the early stages of amniote development consist of large scale rotatory movements over a discoidal blastula (Wetzel, 1924). Such rotatory movements reshuffle a mass inside a finite volume, and thus may have to bear physical conservation laws which contribute to establish the plan of animals in a global fashion. In this article I use dual dorso-ventral imaging of the chicken blastula, to show experimentally that the global movement of early vertebrate embryogenesis is organized with a very simple topology, around and away of a series of hyperbolic points in the vector flow of movement. At the first hyperbolic point, a layer of tissue (the mesoderm) ingresses and moves as a viscous sheet radially. It is found that the sheet flows away with a scaling law for the radius R(t)～exp(t/τ). Also, the movement of this mesoderm changes the flow on the other layer (the ectoderm) by the principle of action and reaction. By mesoderm wetting the ectoderm, the first hyperbolic point migrates from the anal region, to the umbilical region. The final location of the hyperbolic point defines eventually the central part of the body (the umbilical region). Thus, the formation of the vertebrate body is fixed, as a global movement, by the dynamics of singular points in the visco-elastic flow, governed by mechanical forces within the tissue.     

Degradation phase of apoptosis during the early stages of human metanephros development

Apoptosis as a vital process is necessary for human intrauterine development. Not only the induction and course of apoptosis, but engulfment of the apoptotic cells (bodies) were the centre of our interest. Macrophages were detected in the early stages of human intrauterine development and the role of macrophages in the clearance of apoptotic cells in the early stages of human metanephros development was confirmed.     

Microspore embryogenesis in wheat: new marker genes for early, middle and late stages of embryo development

Microspore embryogenesis involves reprogramming of the pollen immature cell towards embryogenesis. We have identified and characterized a collection of 14 genes induced along different morphological phases of microspore-derived embryo development in wheat (Triticum aestivum L.) anther culture. SERKs and FLAs genes previously associated with somatic embryogenesis and reproductive tissues, respectively, were also included in this analysis. Genes involved in signalling mechanisms such as TaTPD1-like and TAA1b, and two glutathione S-transferase (GSTF2 and GSTA2) were induced when microspores had acquired a ‘star-like’ morphology or had undergone the first divisions. Genes associated with control of plant development and stress response (TaNF-YA, TaAGL14, TaFLA26, CHI3, XIP-R; Tad1 and WALI6) were activated before exine rupture. When the multicellular structures have been released from the exine, TaEXPB4, TaAGP31-like and an unknown embryo-specific gene TaME1 were induced. Comparison of gene expression, between two wheat cultivars with different response to anther culture, showed that the profile of genes activated before exine rupture was shifted to earlier stages in the low responding cultivar. This collection of genes constitutes a value resource for study mechanism of intra-embryo communication, early pattern formation, cell wall modification and embryo differentiation.     

The expression of the apolipoprotein A-1 gene in the early stages of human embryogenesis studied by hybridization in situ]

The apolipoprotein A-1 (apo A-1) gene expression at certain stages of human embryo development was studied using an in situ hybridization procedure. By the fifth week of development, the presence of apo A-1 mRNAs was detected in cells of different tissue types such as CNS rudiment, somite myotomes, ear vesicle, nasal placodes, lens, apical areas of the maxillary, mandibular and hyoid arcs, mesenchyme of limb buds, small intestine, mesonephros, genital ridge, and several types of blood cells. At later stages (weeks 8-9) the distribution of these mRNAs showed considerable changes. The high apo A-1 mRNA level was characteristic of liver cells, adrenals, kidney, neural tube and ganglia. These data suggest that changes in tissue-specific apo A-1 gene expression during human embryogenesis may be associated with the development of blood circulatory system and CNS.     

早期胚胎的发育选择:性别决定

性别决定是一个复杂的发育调控过程, 早期胚胎发育过程中, 雌雄二者必居其一的发育选择是胚胎性腺形成必须的发育决定。文章综述了动物性别决定的遗传系统、性腺发生、性别决定关键基因及其作用机制, 从分子进化的角度分析了性染色体与性别决定形成机制, 提示性别决定基因在进化中总是趋向异配性染色体。     

The study of proteins during early stages of embryogenesis of sea urchins

Summary The distribution of the preexisting and of thede novo synthesized proteins among soluble, and insoluble fractions, as well as between immunoprecipitable and non-immunoprecipitable soluble proteins has been studied in sea urchin embryos at different stages of development.In the S-100 fraction, which represented about 20% of total proteins, only a minor part of radioactivity was found. The majority of newly synthesized proteins was insoluble at neutral pH. Such distribution was practically invariant for all investigated stages of development, and was not markedly affected by Dactinomycin nor by 5-azacytidine.Only a small percentage of the total radioactivity of the S-100 fraction was found in the antigen-antibody complexes of soluble proteins. No shift of newly synthesized proteins towards the type of old, preexisting antigenic proteins was detected, and the majority of soluble newly synthesized proteins was found to be related to the non-immunoprecipitable soluble proteins.The authors gratefully acknowledge a generous gift of 5-azacytidine from Drs. Doskoil and ponar. We are also indebted to Dr. Miroslav Simi for kind interest and discussion.This work was supported in part by grants No 3111/1 from Federal Research Fund of Yugoslavia and No 02-020-1 from the National Institute of Health, U. S. Department of Health, Education and Welfare (PL-480 programme).