Effect of nitrobenzoic acid on methemoglobin content in blood and activity of antioxidative enzymes in erythrocytes]

Intraperitoneal administration of meta-nitrobenzoic, 3,5-dinitrobenzoic, 2,4,6-trinitrobenzoic and 3,5-dinitro-4-methylbenzoic acids to the white mice in a dose equal to LD50 has induced an increase in the methaemoglobin content in their blood. Total activity of dehydrogenases of pentosephosphate pathway, content of 2,3-diphosphoglycerate increase in response to the intoxication evoked by the mentioned acids. The acute intoxication does not practically change the activity of the key enzymes of antioxidant protection: superoxide-dismutase, catalase and glutathione peroxidase.     

Morphology of the Respiratory Trees in the Holothurians Apostichopus japonicus and Cucumaria japonica

The morphology of the respiratory trees in the holothurians Apostichopus japonicus and Cucumaria japonica was studied using histochemical and electron microscopic techniques. The epithelium of the respiratory tree cavity in A. japonicus consists of columnar cells about 17–20 m high. In C. japonica, this epithelium is composed of two cell types: bulbous cells embedded in the connective tissue layer and secretory cells; cells are 1–12 m high. A characteristic feature of cells of the respiratory tree cavity epithelium in these species is the presence of numerous phagosomes and coated vesicles in the apical cytoplasm. The cell surface has many microvilli and a single cilium. Cells of the coelomic epithelium contain vacuoles in the apical part and myofibrils in the basal region; the thickness of this epithelium in A. japonicus and C. japonica is 9–16 and 10–30 m, respectively. Based on the different structure of the respiratory trees and the absence of hemocytes in A. japonicus, it is suggested that the holothurian species studied have different routes of oxygen transport from the environment to the internal organs.     

Destruction of human blood cells upon interaction with detonation nanodiamonds in experiments in vitro

The influence of nanodiamonds synthesized by detonation on human red and white blood cells in vitro was studied. Nine nanodiamond samples produced by different manufacturers and two samples of modified nanodiamonds with high colloidal stability were used in the study. It was shown that nanoparticles cause the destruction of white cells and the hemolysis of erythrocytes. Possible mechanisms of the desctructive effect of detonation nanodiamonds on blood-forming elements are discussed.     

Asexual reproduction, evisceration, and regeneration in holothurians (Holothuroidea) from Nha Trang Bay of the South China Sea

Peculiarities of asexual reproduction, evisceration, and regeneration were studied in 13 holothurian species of the orders Dendrochirotida and Aspidochirotida from Nha Trang Bay of the South China Sea. Asexual reproduction by fission has been described for the first time for Cladolabes schmeltzii. It has been shown for the first time that transected C. schmeltzii and Colochirus robustus successfully regenerate not only their anterior, but also their posterior structures. It was found that Pseudocolochirus violaceus was able to regenerate the anterior part of the body and to eject viscera through the anus. The modes of evisceration and regeneration of the gut have been elucidated for ten species of aspidochirotids. It has been shown that the intestine of Holothuria scabra forms from two anlagen rather than from a single one, as previously believed.     

Development of respiratory trees in the holothurian <Emphasis Type="Italic">Apostichopus japonicus</Emphasis> (Aspidochirotida: Holothuroidea)

The development of respiratory trees in the holothurian Apostichopus japonicus has been studied using light and electron microscopy. Primordial respiratory trees emerge in 2–3-mm-long animals (2 months after fertilization). They arise as two independent outgrowths from the dorsal wall of the anterior part of the cloaca. Upon first emerging and throughout the course of development, the left respiratory tree is longer than the right one. A common base develops in 4-mm-long animals (2–3 months after fertilization). In yearlings, the left respiratory tree grows into gaps between the loops of the intestinal tube interlaced with intestinal hemal vessels. The developing coelomic and luminal epithelia have ultrastructural peculiarities. The luminal epithelium of respiratory trees has been shown for the first time to comprise nerve cells and their processes. Characteristic structural features of the epithelia are shown to begin developing as early as in 4-mm-long animals (2–3 months after fertilization). In yearlings, the respiratory trees demonstrate definitive structural patterns and are entirely functional.     

Variability of Regeneration Mechanisms in Echinoderms

Russian Journal of Marine Biology - Several fundamentally different pathways may exist to restore a lost structure in closely related species or within the same species of multicellular animals;...     

Proteases from the Regenerating Gut of the Holothurian Eupentacta fraudatrix

Four proteases with molecular masses of 132, 58, 53, and 47 kDa were detected in the digestive system of the holothurian Eupentacta fraudatrix. These proteases displayed the gelatinase activity and characteristics of zinc metalloproteinases. The 58 kDa protease had similar protease inhibitor sensitivity to that of mammalian matrix metalloproteinases. Zymographic assay revealed different lytic activities of all four proteases during intestine regeneration in the holothurian. The 132 kDa protease showed the highest activity at the first stage. During morphogenesis (stages 2–4 of regeneration), the highest activity was measured for the 53 and 58 kDa proteases. Inhibition of protease activity exerts a marked effect on regeneration, which was dependent on the time when 1,10-phenanthroline injections commenced. When metalloproteinases were inhibited at the second stage of regeneration, the restoration rates were decreased. However, such an effect proved to be reversible, and when inhibition ceased, the previous rate of regeneration was recovered. When protease activity is inhibited at the first stage, regeneration is completely abolished, and the animals die, suggesting that early activation of the proteases is crucial for triggering the regenerative process in holothurians. The role of the detected proteases in the regeneration processes of holothurians is discussed.     

Transdifferentiation in holothurian gut regeneration

It has recently been shown that the whole spectrum of cell types constituting a multicellular organism can be generated from stem cells. Our study provides an example of an alternative mechanism of tissue repair. Injection of distilled water into the coelomic cavity of the holothurian Eupentacta fraudatrix results in the loss of the whole digestive tract, except the cloaca. The new gut reforms from two separate rudiments. One rudiment appears at the anterior end of the body and extends posteriorly. The second rudiment grows anteriorly from the cloaca. In the anterior rudiment, the luminal epithelium (normally derived from endoderm) develops de novo through direct transdifferentiation of the coelomic epithelial cells (mesodermal in origin). In the posterior rudiment, the luminal epithelium originates from the lining epithelium of the cloaca. After 27 days, the two rudiments come into contact and fuse to form a continuous digestive tube lined with a fully differentiated luminal epithelium. Thus in this species, the luminal epithelia of the anterior and posterior gut rudiments develop from two different cell sources-i.e., from the mesodermally derived mesothelium and the endodermally derived epithelium of the cloacal lining, respectively. Our data suggest that differentiated cells of echinoderms are capable of transdifferentiation into other cell types.     

New data on asexual reproduction,autotomy, and regeneration in holothurians of the Order Dendrochirotida

The features of asexual reproduction, autotomy, and regeneration in five species of holothurians from the Order Dendrochirotida which live in the Nha Trang Bay of the South China Sea were studied. In Colochirus robustus, the ability to perform fission was corroborated. It was shown that Cladolabes schmeltzii can redivide without completing its regeneration after a previous division. This process is similar to the fragmentation of other holothurians. The features of autotomy and regeneration in Colochirus quadrangularis, Ohshimella ehrenbergi and Massinium magnum were described for the first time.