The role of cytoplasmic domains in the determination of the fates of ectodermal and mesodermal cells has been investigated in leech embryos. When yolk-deficient cytoplasm (teloplasm) was extruded from the animal pole of the zygote, the ectodermal precursor blastomere was converted to a mesodermal fate. This change of fate can be prevented by replacement of the extruded animal teloplasm with tel...

One of the earliest and most-fundamental pattern- formation events in embryonic development is endoderm and mesoderm specification. In sea urchin embryos, this process begins with blimp1 and wnt8 gene expression at the vegetal pole as soon as embryonic transcription begins. Shortly afterwards, wnt8/blimp1 expression spreads to the adjacent ring of mesoderm progenitor cells and is extinguished i...

land use of sylhet has changed gradually. this is found from the field survey that in 1970 the area was dominated by marshy land (645.33 katha), vacant land (430.88 katha) and crop land (336.17 katha). by 1988 there was no university in the area. residential area also increased. it covered 39.11 % of total study area. now in 2007 there is a radical change noticed in the area in comparison with ...

abstractthe challenges of agroforestry systems’ adoption by farmers in the north central zone of nigeria, was carried out to address the following objectives; find out the perception of farmers on agroforestry technologies, identify the adoption level and ascertain why farmers discontinue agroforestry adoption.. data were collected from 722 agroforestry farmers out of 782 sets of questionnaire ...

Bounoure (1934) first described the presence in the egg of the frog Rana temporaria of a special cytoplasmic differentiation, which he termed the 'ger-minal cytoplasm'. He was able to trace the developmental history of this plasm as it moved from its original position just under the cortex of the vegetal pole of the fertilized egg, to its inclusion in a number of cells of the early gastrula end...

Mesoderm induction was first demonstrated by Pieter Nieuwkoop in 1969. By recombining animal and vegetal explants, which would in isolation originate ectoderm and endoderm, respectively, mesoderm formed from the animal cap cells (Nieuwkoop, 1969). Successive research has identified candidate mesoderm inducers within the TGFβ and FGF families of molecules (reviewed in Harland and Gerhart, 1997)....

Previous studies of the regulatory region of the SpHE (hatching enzyme) gene of the sea urchin Strongylocentrotus purpuratus (Wei, Z., Angerer, L.M., Gagnon, M.L. and Angerer, R.C. (1995) Characterization of the SpHE promoter that are spatially regulated along the animal-vegetal axis of the sea urchin embryo. Dev. Biol. 171, 195-211) have shown that approximately 330 bp is necessary and suffici...

Dishevelled (Dsh) is a key signaling molecule in the canonical Wnt pathway. Although the mechanism by which Dsh transduces a Wnt signal remains elusive, the subcellular localization of Dsh may be critical for its function. In the early sea urchin embryo, Dsh is concentrated in punctate structures within the cytoplasm of vegetal blastomeres. In these cells, Dsh stabilizes beta-catenin and causes...

The resumption of the meiotic cycle (maturation) induced by 1-methyladenine in prophase-arrested starfish oocytes is indicated by the breakdown of the germinal vesicle and is characterized by the increased sensitivity of the Ca2+ stores to inositol 1,4,5-trisphosphate (InsP3) to InsP3 starting at the animal hemisphere (where the germinal vesicle was originally located) and propagating along the...

The use of dynamized substances in agriculture, especially on plants, has been growing fast. Diseases or physiological disorders are not considered merely the results action physiopathological agents and abiotic factors, but a consequence loss homeostasis organism. Notions proper to homeopathy used several areas agriculture. Although effective have observed both academic field milieus, too much...