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PubMedDate not supplied

[Biological experiments on "Kosmos-1887"].

In the 13-ray space flight on Kosmos-1887 various experiments in the field of cell biology, genetics, biorhythm, developmental biology and regeneration were performed using bacteria, protozoa, plants, worms, insects, fish and amphibia. Paramecia showed enhanced cell proliferation, spheroidization and diminished protein content. Experiments on fruit-flies, newt oocytes and primate lymphocytes confirmed involvement of the cell genetic apparatus in responses to microgravity. Beetles exhibited a reduction of the length of the spontaneous period of freely running circadian rhythms. Carausius morosus developed latent changes in early embryogenesis which manifested at later stages of ontogenesis. Exposure to microgravity did not prevent recovery of injured tissues; moreover their regeneration may be accelerated after recovery. Biology research programs in future biosatellite flights are discussed.

Aerospace Medicine↗
PubMed1989

[Evolutionary biological aspects of the physiology of extracorporeal CO2 removal].

Extracorporeal CO2 elimination (ECCO2-R) is a new approach to the treatment of severe respiratory failure. Gas exchange is separated into oxygen uptake by apneic oxygenation through the natural lungs while CO2 is removed extracorporeally with an artificial organ. The physiological conditions of both processes can thus be optimized. In the course of evolution, a similar bimodal gas exchange has developed during the respiratory transition from aquatic gas exchange to pulmonary gas exchange: In air-breathing fish or amphibia oxygenation is accomplished predominantly via the lungs while CO2 is eliminated via gill or skin. Today's air-breathing vertebrates maintain a considerable respiratory acidosis which has to be compensated for by an appropriate bicarbonate level. This is dependent upon gill reduction and skin armor to prevent evaporation leading to a rise in pCO2 from 3-4 to 40 mmHg and a tenfold increase of serum bicarbonate levels. We believe that the developmental history of respiration justifies the use of a bimodal gas exchange system. It is clinically applied as extracorporeal CO2 removal with membrane lungs (ECCO2-R) or, still under investigation, in a hemodialysis-related procedure (extracorporeal bicarbonate/CO2 removal: ECBicCO2).

Animals↗
PubMed1989

Changes in motor nerve terminals during bupivacaine-induced postsynaptic deprivation.

The local anaesthetic agent bupivacaine induces a rapid degeneration of muscle cells when injected in the sternocleidomastoid muscle of the adult rat with no damage to intramuscular nerves. Nevertheless, silver impregnation and electron microscopy reveal a sequence of retraction and sprouting of the motor nerve endings during the period of the bupivacaine-induced muscle cell deprivation by necrosis. These morphological changes seem to be qualitatively similar to the retraction and growth phenomena described as forming part of the remodelling process affecting normal untreated neuromuscular junctions of the adult amphibia and mammals. The results are discussed in the context of the regulatory mechanisms governing the maintenance of motor nerve terminals.

Animals↗
PubMed1989

Central axonal regeneration and autoimmunity in adult birds.

After traumatic lesion adult cock spinal cord displays lively axonal regenerative activity. After 22 days, morphological regeneration regresses; functional regeneration is never observed. Before and after spinal lesion in the cocks, IgG decoration of myelin sheaths is never observed. The sera of both injured and intact animals tested both by immunohistochemical methods on intact spinal cord sections and by immunoelectrophoresis on a protein extract of homologous spinal cord are always negative. The authors suggest that the absence in Birds of any autoimmune response against c.n.s. antigens after surgical exposition, as observed in Mammals, is possibly related to the capacity of the central axons to regenerate in Birds, as observed by the Authors in Amphibia and Reptilia (Triturus and Lacerta).

Animals↗
PubMed1989

Primordial germ cell proliferation in the salamander Pleurodeles waltl: genetic control before gonadal differentiation.

PGC counts were carried out on larvae of Pleurodeles waltl (urodele amphibia) issued from standard, monosexual male and monosexual female offspring while the genital ridges were settling. During this period, which is characterized by a zero mitotic index (and is therefore called the Po period), and which lasts from stage 35 to stage 41, no PGC proliferation occurs. A statistical analysis indicated that PGC counts per larva are sex genotype independent and that offspring may be divided into three groups with average PGC counts of 96.9, 51.0 and 31.1, respectively. A fourth group with an average of 18.3 PGCs has been identified using experimental larvae reared at 30 degrees C from stage 30. The PGC count of 96.9 would result from at least three mitotic cycles. Before the Po period, germ cells are not identifiable. A hypothesis concerning genetic control of PGC proliferation before Po was deduced from this analysis.

Animals↗
PubMed1989

Acetylcholinesterase activity in the adrenal chromaffin vesicles of Urodela.

The presence of acetylcholinesterase (AChE) activity in the adrenal chromaffin cells of Necturus maculosus and Ambystoma maculatum (Amphibia, Urodela) has been demonstrated by cytochemical method at the electron microscope level. The enzymatic activity is localized in RER and perinuclear cisternae, on the plasma membrane and within the chromaffin vesicles, both in adrenaline (A) and noradrenaline (N) cells. Moreover N cells appear to be more reactive than A cells and Necturus more reactive than Ambystoma. The possible function of the AChE activity inside the vesicles is discussed as a mechanism of protons donor or as peptidasic activity acting on various peptides present in the vesicle.

Acetylcholinesterase↗
PubMed1989

The harderian gland of the frog, Rana esculenta, during the annual cycle: histology, histochemistry and ultrastructure.

The Harderian gland in Rana esculenta has been studied during the annual cycle at the histological, histochemical and ultrastructural levels. The Harderian gland has an acinar structure and is the only orbital gland in anuran amphibia. It develops at the medial corner of the orbit from the conjunctival epithelium at the premetamorphic stage. In the adult the glandular secretion reaches a maximum during the months of July and August, drops in September and resumes slowly from October onwards. The secretion is seromucoid and the secretory granules are released into the acinar lumen, mainly by exocytosis. Porphyrins were not detected. No sexual dimorphism was observed in the glandular cells. The resumption of secretory activity in October and the enhancement of secretion in May are marked by the appearance of "blue nuclei" (Mallory stain) in a relatively high percentage of glandular cells. This unusual blue colour, using the Mallory stain (by which nuclei stain red), disappears after digestion of paraffin sections with RNAase, but not with DNAase and trypsin. The blue staining may, therefore, indicate an increased amount of nuclear RNA. The Harderian gland in the frog most probably serves to lubricate and moisten the eye in the absence of the lacrimal gland. However, the gland may also represent an immunoactive organ owing to the presence of numerous mast cells and plasma cells in the interacinar spaces.

Animals↗
PubMed1987

Phospholipid transfer activities in toad oocytes and developing embryos.

The role of lipid transfer proteins during plasma membrane biogenesis was explored. Developing amphibia embryos were used because during their growth an active plasma membrane biosynthesis occurs together with negligible mitochondrial and endoplasmic reticulum proliferation. Sonicated vesicles, containing 14C-labeled phospholipids and 3H-labeled triolein, as donor particles and cross-linked erythrocyte ghosts as acceptor particles were used to measure phospholipid transfer activities in unfertilized oocytes and in developing embryos of the toad Bufo arenarum. Phosphatidylcholine transfer activity in pH 5.1 supernatant of unfertilized oocytes was 8-fold higher than the activity found in female toad liver supernatant, but dropped steadily after fertilization. After 20 hr of development, at the stage of late blastula, the phosphatidylcholine transfer activity had dropped 4-fold. Unfertilized oocyte supernatant exhibited phosphatidylinositol and phosphatidylethanolamine transfer activity also, but at the late blastula stage the former had dropped 18-fold and the latter was no longer detectable under our assay conditions. Our results show that fertilization does not trigger a phospholipid transport process catalyzed by lipid transfer proteins. Moreover, they imply that 75% of the phosphatidylcholine transfer activity and more than 95% of the phosphatidylinositol and phosphatidylethanolamine transfer activities present in pH 5.1 supernatants of unfertilized oocytes may not be essential for toad embryo development. Our findings do not rule out, however, that a phosphatidylcholine-specific lipid transfer protein could be required for embryo early growth.

Acetates↗
PubMedDate not supplied

[Concentration and composition of gangliosides in portions of the vertebrate brain].

Studies have been made on gangliosides from various parts of the brain in 5 species of cartilaginous fishes, 2 species of teleosts, 2 amphibian species, 2 avian species and 3 species of mammals. Almost in all the species investigated, the highest content of gangliosides per weight unit of the brain were found in the forebrain (determinations were carried out by sialic acid, sometimes by sphingosine). Ganglioside content of brain structure in warm-blooded animals is higher that in corresponding structures of fishes and amphibia. Comparative studies on ganglioside composition in the brain of fishes and mammals indicate that brain structures exhibit the same pattern of molecular organization, as the whole brain of the species studied (high polysialoganglioside content in teleosts, predominance of gangliosides with a short carbon chain in cartilaginous fishes, etc.). Besides this fact, peculiarities of composition typical of the brain structures were found as well (more polar composition of gangliosides of the cerebellum and some other ones).

Animals↗
PubMedDate not supplied

Electron cytochemistry of peroxidase activity in neutrophils of the bone marrow of the frog Rana temporaria.

The bone marrow of the frog was studied during the spring and winter periods. During the winter period, one type of large granules in the neutrophils of the frog proved to be peroxidase-positive. The remaining, smaller granules are peroxidase-negative. In the spring, immature and mature neutrophils are encountered in the frog. The mature neutrophils of the frog in the spring and winter periods are analogous. The immature neutrophils contain peroxidase activity in the perinuclear space, the endoplasmic reticulum and some of the granules. Some of the peroxidase-containing granules are directly associated with the canals of the endoplasmic reticulum. In the immature neutrophils, during the formation of the peroxidase-containing granules, peroxidase-negative granules smaller in size are already present in the cytoplasm. Thus, the sequence of granule formation usual for mammals is apparently not observed in the neutrophils of certain amphibia. "Annular" mitochondria, encompassing part of the cytoplasm were detected in the neutrophils. These apparently represent a section through a spherical mitochondrion enveloping and isolating a certain zone of the cell. It is proposed that the mitochondria in this way, differing from the lysosomal mode, participate in the catabolism of the cytoplasm.

Animals↗
PubMed1979

Membrane addition to photoreceptor outer segments: progressive reduction in the stimulatory effect of light with increased temperature.

Previous studies have indicated that temperature and light regimens affect the rates of membrane addition to rod outer segments in amphibia. However, it is not known how membrane renewal responds to simultaneous alterations of these two environmental factors. In the present study, the rates of membrane addition have been assessed in adult Rana pipiens maintained in three lighting conditions (constant light, constant darkness, and cyclic light) at three different temperatures by following the displacement of a radioactive band in autoradiographs after 3H-leucine injection. At 16 degrees, 21 degrees, and 26 degrees C, constant light increases the rate of membrane addition in red rods above the rates which occur in darkness by 39%, 14%, and 9%, respectively, whereas in the green rods, the rates of increase were 41%, 22%, and 8%. This progressive reduction in the stimulatory effect of light suggest that at the higher temperatures, rod outer segment renewal is proceeding at near maximal rates and can no longer be further accelerated by light stimulation.

Animals↗
PubMed1985

Suppression in Xenopus laevis: thymus inducer, spleen effector cells.

Studies were carried out on suppressor function in the amphibian Xenopus laevis, the South African clawed toad. Suppression by the thymus of haemagglutinin (HA) production by spleen is antigen-dependent, partially specific and not MHC-restricted in this species (Ruben, Buenafe & Seivert, 1983). Three questions were considered in this study. Does the thymus effect suppression by stimulating peripheralized spleen effector cells, or do effector cells reside within the thymus? Do macrophages participate in the induction and/or expression of thymus-dependent suppressor function? Can thymus suppressor and helper functions be distinguished by using irradiation treatment? The capacity of immunized thymus to suppress HA when co-cultured with spleen fragments from immunized, cyclophosphamide (CyP)-injected animals was tested. Immunized thymus failed to suppress the high levels of HA production by spleen fragments from CyP-treated, immunized donors. Colloidal carbon injection resulted in blockade of macrophage function, and both the capacity of thymuses to suppress and of spleens to be suppressed in co-cultures. Finally, the effect of thymus exposure to gamma-irradiation in vitro was tested using autogeneic thymus/spleen combinations. This enabled the visualization of thymic helper function, which is MHC-restricted in Xenopus (Bernard et al., 1981). Four dosages of irradiation were tested after antigen challenge. The highest HA titres were produced by spleen co-cultures with thymuses which had received 1000 rads. We conclude that suppression of HA production in spleen is not the result of thymus suppressor effector cells, but that suppressor function is mediated by thymus inducer cells which stimulate suppressor effectors in spleen. Both the thymic inducers and effectors in the spleen are sensitive to CyP and macrophage blockade. Our studies further suggest that we are able to distinguish between the thymic functions of help and suppression in Xenopus by taking advantage of their differential sensitivities to irradiation. While it has been postulated, on other grounds, that suppression was one of the earliest thymic regulatory functions to have evolved (L.N. Ruben & R.H. Clothier, submitted), here we suggest the presence of sequential activities of more than one cellular subset, as early in evolution as the primitive anuran (tail-less) amphibia.

Animals↗
PubMedDate not supplied

[Various aspects of evolution of Alu repeats in mammals].

A complex study on various evolutionary peculiarities of the mammalia dispersed Alu repeats (Alu repeats of primates and B1 of rodents) has been carried out by phylogenetic analysis. A phylogenetic tree, containing the 7SL RNA genes and the Alu repeats of primates and rodents has been constructed. It has been shown that the branch of the phyletic line leading to the Alu repeats of primates and B1 of rodents from the 7SL RNA genes occurred after the divergence of the 7SL RNA genes of amphibia and mammalia, but before the divergence of the 7SL RNA genes of primates and rodents (250.10 years ago). A statistically reliable slowing down in the evolutionary rates of one of two monomers for the human Alu repeats has been proved. It may be caused by the functional load of the corresponding monomer in connection with the presence of a definit regulatory site in it.

Animals↗
PubMed1988

Oxygen regulation capacity in Discoglossus pictus tadpoles between moderate hyperoxia and acute hypoxia in water.

The oxygen dependence of aquatic oxygen consumption was measured in active and anesthetized stage XVIII Discoglossus pictus tadpoles (Amphibia, Anura). The active tadpoles are good oxygen regulators in moderate hyperoxia and moderate hypoxia, whereas they are oxygen conformers in acute hypoxia. Critical oxygen pressure was 52 mmHg O2. Anesthetizing the larvae changes them to perfect oxygen conformers between moderate hyperoxia and moderate hypoxia (249-63 mmHg O2). At stage XVIII the aquatic respiratory organs are still capable of producing oxygen regulation when free access to air is denied. The marked capacity for oxygen regulation in D. pictus tadpoles is concordant with the strong hypoxic environments in which these animals usually live in nature.

Animals↗
PubMed1988

[Comparative characteristics of adrenergic innervation of the cerebrospinal arteries of vertebrates and man].

Adrenergic innervation of the cerebrospinal arteries in redeye, frog, tortoise, hen, sea-gull, guinea-pig, rabbit, cat, dog and man has been studied by means of fluorescent-histochemical method. In all the animals there is a similar principle of innervation. The nervous apparatus is revealed as continuous integral plexuses. In the process of historical development the role of the nervous factor in regulation of the cerebrospinal circulation is increasing. As the innervational degree of the spinal arteries decreases, the vertebrates make the following line: mammals, birds, reptiles, amphibia, fishes. In all the animals, besides the fishes, the greatest concentration of the nervous fibers is revealed in the areas of the spinal cord thickenings.

Animals↗
PubMed1988

Patterning of connective tissues in the head: discussion report.

The three papers presented by Noden, Thorogood and Lumsden in this session encompassed the connective tissues as broadly defined, i.e. soft (fibrous) connective tissue, cartilage, bone, muscle and the dental tissues, enamel and dentine, and utilized a variety of experimental techniques on both avian and mammalian embryos to explore specificity and patterning of the vertebrate head. Whether similar developmental processes pattern homologous structures in different Vertebrate classes (Amphibia, Aves, Mammalia) was discussed with reference to patterning of the cranial musculature, chondrocranium and dental tissues. A number of challenging ideas emerged during this session. Does the premigratory neural crest consist of a homogenous population of totipotent cells or of subpopulations of bi- or tripotential cells? Is fundamental patterning of the head an early embryonic event, perhaps specified during primary embryonic induction or the consequence of neuroepithelial folding, brain growth, inductive interactions and/or spatially and temporally distributed extracellular matrix products? Can the fact that mesoderm and angioblasts do not display distinctive patterning that relates to their particular embryologic origins be extrapolated to patterning in general? How does the documentation of an odontogenic trunk neural crest in mammals affect our theories of how patterning mechanisms arose or were modified during vertebrate evolution?

Animals↗
PubMed1988

[Recapitulation in the development of the components of the counterflow system in the vertebrate metanephros].

The investigation has been performed on 107 renal preparations obtained from persons of various age (from 5-month-old fetuses up to 45 years of age), certain representatives of other classes of the Vertebrata are also included: fish, amphibia, reptile and mammalia at various stages of pre- and postnatal periods of ontogenesis by means of preparing graphic and plastic reconstructive models, histological investigation and microdissection. The complexity of the intrarenal branching of derivatives of the mesonephric duct diverticulum, development and structure of the canalicular part in nephrons directly depend on the phylogenetic position of the animal. Complexity of the nephron architectonics occurs along the progressive line of taxonomic groups of higher Vertebrata. The nephron loop becomes longer, thin segment of the nephron canalicular part increases in its length and, at last, in mammalia a cone-shaped fasciculus appears as a structural-functional unit of the osmoregulating apparatus of the constant kidney. In the comparative anatomical and comparative embryological aspects recapitulation is observed concerning certain morphological signs of derivatives of the metanephric duct and nephron.

Animals↗
PubMed1987

Phylogeny of C4b-C3b cleaving activity: similar fragmentation patterns of human C4b and C3b produced by lower animals.

Functional and structural studies of the activated proteins of the complement system C4b and C3b have led to the identification of cleavage products resulting from the effect of the regulatory proteins, factor I, H, and C4b binding protein (bp). In this paper we report the results of studies that investigated the capacity of plasma or serum from a wide range of phylogenetic species to yield similar cleavage products. Sera and plasma from mammals, reptiles, amphibia, and fishes are capable of cleaving fluid phase human C4b and C3b, generating apparently the same fragments as observed using normal human serum: alpha 2, alpha 3, alpha 4 from the alpha' chain of C4b: and alpha-68, alpha-46, alpha-43, and alpha-30 from the alpha' chain of C3b. When C3b bound to a cell membrane is used C3c and C3dg are generated. The generation of these fragments from C3bi is a dose-dependent reaction. There is no correlation between the evolution of the species and the quantitative capability to degrade the substrates. Birds possess only a limited capability to degrade the alpha' chain of C4b and have no cleaving activity for C3b, whereas sera from more primitive vertebrate species (chondrichthyes and agnatha) fail to participate in the reaction. Contrary to other species, the proteins in fish serum or plasma responsible for the degradation of C4b and C3b show a unique requirement for Ca2+ ions. Magnesium and barium are less effective, and in their presence a 65,000 dalton intermediate product is observed. These results demonstrate that protein(s) displaying proteolytic activity for products of complement activation, probably related to I, H, and C4bp, are present in plasma of species whose evolution have preceded humans by 300 million years. Moreover, the recognition of human substrates and the generation of fragments identical to those produced by human serum suggests that human C4b and C3b share structural characteristics with their evolutionary ancestors in the serum or plasma of the species studied.

Animals↗