نتایج جستجو برای: metamorphosis
تعداد نتایج: 5013 فیلتر نتایج به سال:
Development of the olfactory epithelia of the African clawed frog, Xenopus laevis, was studied by scanning and transmission electron microscopy. Stages examined ranged from hatching through the end of metamorphosis. The larval olfactory organ consists of two chambers, the principal cavity and the vomeronasal organ (VNO). A third sensory chamber, the middle cavity, arises during metamorphosis. I...
Multipotent neural crest stem cells have been identified in late gestation amniote embryos. Yet, significant questions remain about the mechanisms by which these cells are generated, maintained, and recruited during postembryonic development. The zebrafish, Danio rerio, offers an opportunity to identify genes essential for these processes, by screening for mutants with defects in traits likely ...
A metamorphosis in the etiology of valvular heart disease (VHD) has occurred over the last 6 decades. In this review, the factors contributing to this metamorphosis, the common causes of VHD today, the relationship of valvular calcification to atherosclerosis and the interrelationship of VHD with other systems/organs are presented.
American toad (Bufo americanus) tadpoles were exposed to cadmium from shortly after hatching through metamorphosis. Cadmium at 540 microg/L decreased percentage survival and metamorphosis; 5 and 54 microg/L increased growth relative to controls. Amphibians exposed to cadmium as tadpoles may be less tolerant of natural stressors in the terrestrial environment.
Insect molting and metamorphosis are intricately governed by two hormones, ecdysteroids and juvenile hormones (JHs). JHs prevent precocious metamorphosis and allow the larva to undergo multiple rounds of molting until it attains the proper size for metamorphosis. In the silkworm, Bombyx mori, several "moltinism" mutations have been identified that exhibit variations in the number of larval molt...
A λ-fold G-design of order n is a pair (X, B), where B is a collection of edge disjoint copies of the simple graph G which partitions the edge set of λK n (the undirected complete graph with n vertices) with vertex set X. Let (X, B) be a G-design and H be a subgraph of G. For each block b ∈ B, partition b into copies of H and G \ H and place the copy of H in B(H) and the edges belonging to the ...
Artificial inducers have been used to study signal-transduction pathways involved in metamorphosis of some marine invertebrates. However, the transduction mechanisms for echinoderms have been less explored. In the present study, participation of protein kinase C (PKC), G-protein-coupled receptors (GPCRs), and calcium has been investigated during metamorphosis of the sea urchin Stronglylocentrot...
Metamorphosis has intrigued biologists for a long time as an extreme form of complex life cycles that are ubiquitous in animals. While investigated from a variety of perspectives, the ecological focus has been on identifying and understanding the ecological factors that aVect an individual’s decision on when, and at what size, to metamorphose. Predation is a major factor that aVects metamorphic...
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