Size of the lesioned portion of the retina after laser exposure (electron microscopic study)

Morphological pattern of the retina in the trauma focus and outside its borders has been studied electron microscopically after application of ruby laser monoimpulse radiation (wave length 0.69 mcm, energy 1.06-1.25 X 10(-4) J and impulse length 20 nc). The trauma focus is not limited only by the volcano-shaped inflation of the retina. The lesion of the photoreceptory ultrastructure and the disturbance of microcirculation in the vascular layer are defined in 3 zones investigated: at the distance 50, 100 and 1,000 mcm from the spot on the retina, visible in the light microscope. This phenomenon should be taken into consideration when choosing therapeutic doses of laser radiation, applied for treatment of various diseases of the eye.     

Formation of structuro-functional units of the microcirculatory bed of muscles in the postnatal period of the ontogenesis of the white rat

By means of biomicroscopy, histological methods and scanning electron microscopy topological relationships between the white rat m. cremaster microvessels and changes of their spatial organization have been studied in the postnatal development beginning from the 3d to the 14th week. In the terminal link of the microcirculatory bed zonal functional complexes of microvessels--myoangions are revealed. They represent rather autonomic and regularly repeating constructions of microvessels, having spatial regularity in respect to muscle fibers. With age the myoangion increases its stretchness from 303 +/- 14 in 3-week-old up to (70 +/- 3) X 10 mcm in 14-week-old animals. Capillary density in the m. cremaster during the development decreases from 354 +/- 12 up to 210 +/- 4 mcm, respectively. Distance between the longitudinal capillaries increases from 16.1 +/- 1.3 up to 31.2 +/- 1.8 mcm. Increase of transversal connections takes place in the capillary network, increasing number of the branching knots; this demonstrates certain complication of the nutritive link of the muscle microcirculatory bed. By the time of sexual maturation (6 weeks) there is a sharp decrease of the inflow and outflow coefficients. Higher meanings of the coefficient (0.70-0.74) are noted before sexual maturation period in comparison to that in mature animals (0.53-0.55).     

P2X2 and P2X3 receptor expression in postnatal and adult rat urinary bladder and lumbosacral spinal cord

P2X receptors mediate the effects of ATP in micturition and nociception. During postnatal maturation, a spinobulbospinal reflex and voluntary voiding replace primitive voiding reflexes. This may involve changes in neuroactive compounds and receptors in bladder reflex pathways. We examined P2X2 and P2X3 receptors in bladder and spinal cord from postnatal (P0-P36, indicating number of days) and adult Wistar rats. Western blot of whole bladders for P2X2 and P2X3 expression was performed. Immunostaining for P2X2 and P2X3 receptors in urothelium and detrusor smooth muscle whole mounts and spinal cord sections was examined. Western blot demonstrated an age-dependent decrease (R(2) = 0.96, P 相似文献   

Paraquat effect on the bioelectric parameters of the rabbit small intestine and its in vitro penetration

The effect of paraquat (in concentrations of 10(-4) and 10(-3) mol/l) was studied on the bioelectric parameters of rabbit small intestine. A short-lasting rise in the potential difference (PD) and some decrease of tissue resistance (R) were observed, particularly after the higher concentration. These changes indicate stimulation of the transport function of the rabbit small intestine as a result of administration of this herbicide. Other tested parameters included determination of the rate of paraquat penetration (at concentration gradient 10(-3) mol/l) across the intestinal wall from the serosal side to the mucosal side and conversely. In the latter case three experimental models were used: first--complete intestinal wall, second--intestinal wall with the serosa stripped off, and third--intestinal wall with the mucosa and serosa removed. Differences were found in these rates depending on the model used. The importance of epithelial cells of the mucosa and subepithelial layers, and mesothelium of the serosa in limiting the penetration of bipirydylium herbicides is stressed.     

A genome-wide screen identifies genes required for formation of the wobble nucleoside 5-methoxycarbonylmethyl-2-thiouridine in Saccharomyces cerevisiae

We recently showed that the gamma-subunit of Kluyveromyces lactis killer toxin (gamma-toxin) is a tRNA endonuclease that cleaves tRNA(mcm5s2UUC Glu), tRNA(mcm5s2UUU Lys), and tRNA(mcm5s2UUG Gln) 3' of the wobble nucleoside 5-methoxycarbonylmethyl-2-thiouridine (mcm(5)s(2)U). The 5-methoxycarbonylmethyl (mcm(5)) side chain was important for efficient cleavage by gamma-toxin, and defects in mcm(5) side-chain synthesis correlated with resistance to gamma-toxin. Based on this correlation, a genome-wide screen was performed to identify gene products involved in the formation of the mcm(5) side chain. From a collection of 4826 homozygous diploid Saccharomyces cerevisiae strains, each with one nonessential gene deleted, 63 mutants resistant to Kluyveromyces lactis killer toxin were identified. Among these, eight were earlier identified to have a defect in formation of the mcm(5) side chain. Analysis of the remaining mutants and other known gamma-toxin resistant mutants revealed that sit4, kti14, and KTI5 mutants also have a defect in the formation of mcm(5). A mutant lacking two of the Sit4-associated proteins, Sap185 and Sap190, displays the same modification defect as a sit4-null mutant. Interestingly, several mutants were found to be defective in the synthesis of the 2-thio (s(2)) group of the mcm(5)s(2)U nucleoside. In addition to earlier described mutants, formation of the s(2) group was also abolished in urm1, uba4, and ncs2 mutants and decreased in the yor251c mutant. Like the absence of the mcm(5) side chain, the lack of the s(2) group renders tRNA(mcm5s2UUC Glu) less sensitive to gamma-toxin, reinforcing the importance of the wobble nucleoside mcm(5)s(2)U for tRNA cleavage by gamma-toxin.     

Histological and histochemical studies of the gall bladder of the graylag goose (Anser anser)

ABSTRACT

We investigated the histological structure of the graylag goose (Anser anser) gall bladder. Sections of the gall bladder were stained with hematoxylin and eosin (H & E), Alcian blue (pH 2.5) for acid mucopolysaccharides, Gomori’s method for reticular fibers, Masson’s trichrome, periodic acid-Schiff (PAS) and Verhoeff’s elastin stain. The goose gall bladder was composed of a tunica mucosa, tunica muscularis and tunica adventitia or tunica serosa. The tunica mucosa formed regularly distributed simple isometric folds plus larger, less numerous, branched folds. The luminal surface was lined by tall columnar epithelial cells that stained for both acid and neutral mucopolysaccharides. The epithelial cells formed a discontinuous striated border of interdigitating microvilli on the luminal surface. Neither a lamina muscularis nor goblet cells were observed in the tunica mucosa. Unusual findings included branched mucosal folds, discontinuous microvilli and absence of an outer longitudinal layer in the tunica muscularis. No marked sex-associated differences were found. The general histochemical and histological structures of the graylag goose gall bladder are similar to those of birds such as chukar partridge and quail, but with some unique elements that may reflect differences in organ function.     

Elemental composition of the human atherosclerotic artery wall

The elemental composition of the human atherosclerotic popliteal artery was examined using the proton-induced X-ray-emission (PIXE) method. The application of a narrow proton beam (3 X 10 micron 2) enabled us to determine not only the concentrations of Cl, K, Ca, Fe, Cu, Zn, Br and Pb, but also their localization in different artery-wall regions. The highest mean concentrations of Cl, K, Zn and Br were found in the tunica media. In the investigated sections the distribution of Ca and Fe varied: sometimes, these elements were prevalent in the tunica intima, whereas in other cases, the highest concentrations were observed in the tunica media or tunica adventitia. The concentration profiles of each element were characterized by many sharp, narrow peaks. The highest concentrations of Ca and Fe showed such high levels that only one explanation is possible, i.e. the presence of crystals. The correlation of Ca peaks with those of Zn and Fe is discussed. The usefulness of the micro-PIXE method for the investigation of biomedical materials is also considered.     

Overexpression of a novel gene , Cms1, can rescue the growth arrest of a Saccharomyces cerevisiae mcm10 suppressor

INTRODUCTIONDNA replication is a fundamenial process thatmust occur only once at each ce1l cycle. This restrictcontrol appears to be achieved through the coordi-nated actiVities of numerous proteins. The buddingyeast Saccharompes cerevhaae provides an excellenteukaryotic model fOr study of proteins invo1ved inthe control of DNA replication.In the budding yeast, minichromosome mainte-nance (MCM) proteins, MCM2-7, are a family of strsequence-related proteins that play crucia1 roles inr…     

Two mcm3 mutations affect different steps in the initiation of DNA replication

Mcm3 is a subunit of the hexameric MCM2-7 complex required for the initiation and elongation of DNA replication in eukaryotes. We have characterized two mutant alleles, mcm3-1 and mcm3-10, in Saccharomyces cerevisiae and showed that they are defective at different steps of the replication initiation process. Mcm3-10 contains a P118L substitution that compromises its interaction with Mcm5 and the recruitment of Mcm3 and Mcm7 to a replication origin. P118 is conserved between Mcm3, Mcm4, Mcm5, and Mcm7. An identical substitution of this conserved residue in Mcm5 (P83L of mcm5-bob1) strengthens the interaction between Mcm3 and Mcm5 and allows cells to enter S phase independent of Cdc7-Dbf4 kinase (Hardy, C. F., Dryga, O., Pahl, P. M. B., and Sclafani, R. A. (1997) Proc. Natl. Acad. Sci. U. S. A. 94, 3151-3155). Mcm3-1 contains a G246E mutation that diminishes the efficiency of replication initiation (Yan, H., Merchant, A. M., and Tye, B. K. (1993) Genes Dev. 7, 2149-2160) but not its interaction with Mcm5 or recruitment of the MCM2-7 complex to replication origin. These observations indicate that Mcm3-10 is defective in a step before, and Mcm3-1 is defective in a step after the recruitment of the MCM2-7 complex to replication origins.     

Overexpression of a novel gene, Cms1, can rescue the growth arrest of a Saccharomyces cerevisiae mcm10 suppressor.

MCM10 protein is an essential replication factor involved in the initiation of DNA replication. A mcm10 mutant (mcm10-1) of budding yeast shows a growth arrest at 37 degrees C. In the present work, we have isolated a mcm10-1 suppressor strain, which grows at 37 degrees C. Interestingly, this mcm10-1 suppressor undergoes cell cycle arrest at 14 degrees C. A novel gene, YLR003c, is identified by high-copy complementation of this suppressor. We called it as Cms1 (Complementation of Mcm 10 Suppressor). Furthermore, the experiments of transformation show that cells of mcm10-1 suppressor with high-copy plasmid but not low-copy plasmid grow at 14 degrees C, indicating that overexpression of Cms1 can rescue the growth arrest of this mcm10 suppressor at non-permissive temperature. These results suggest that CMS1 protein may functionally interact with MCM10 protein and play a role in the regulation of DNA replication and cell cycle control.     

Three-dimensional organization and topographical features of the myenteric plexus (Auerbach) in the porcine small intestine: scanning electron microscopy after enzymatic digestion and HCl-hydrolysis

The present scanning electron microscopical (SEM) study was initiated to visualize the surface topography of Auerbach's plexus in the ileum of the pig. After enzymatic digestion of the connective-tissue components of the tunica muscularis and the tunica serosa followed by glutaraldehyde fixation, HCl-hydrolysis and stripping off either the longitudinal or circular smooth muscle layer, the three-dimensional architecture and topographical features of the myenteric plexus can clearly be observed. In this way, ganglia, primary, secondary and tertiary strands, and single nerve fibres can be demonstrated. Individual nerve cells, which are incompletely covered by glial cells and by remnants of the basal lamina, can be recognized in the centre and periphery of the ganglia and adjacent to primary and secondary nerve strands.     

The phenotype of the minichromosome maintenance mutant mcm3 is characteristic of mutants defective in DNA replication.

MCM3 is an essential gene involved in the maintenance of minichromosomes in yeast cells. It encodes a protein of 971 amino acids that shows striking homology to the Mcm2 protein. We have mapped the mcm3-1 mutation of the left arm of chromosome V approximately 3 kb centromere proximal of anp1. The mcm3-1 mutant was found to be thermosensitive for growth. Under permissive growth conditions, it was defective in minichromosome maintenance in an autonomously replicating sequence-specific manner and showed an increase in chromosome loss and recombination. Under nonpermissive conditions, mcm3-1 exhibited a cell cycle arrest phenotype, arresting at the large-bud stage with an undivided nucleus that had a DNA content of nearly 2n. These phenotypes are consistent with incomplete replication of the genome of the mcm3-1 mutant, possibly as a result of limited replication initiation at selective autonomously replicating sequences leading to cell cycle arrest before mitosis. The phenotype exhibited by the mcm3 mutant is very similar to that of mcm2, suggesting that the Mcm2 and Mcm3 protein may play interacting roles in DNA replication.     

Smooth muscle and purinergic contraction of the human, rabbit, rat, and mouse testicular capsule

The smooth-muscle cells of the testicular capsule (tunica albuginea) of man, rat, and mouse were examined by electron microscopy. They were characteristically flattened, elongated, branching cells and diffusely incorporated into the collagenous matrix and did not form a compact muscle layer. Contractile and synthetic smooth-muscle cell phenotypes were identified. Nerve varicosities in close apposition to smooth muscle were seen in human tissue. Contractions induced by adenosine 5'-triphosphate (ATP), alpha, beta-methylene ATP, noradrenaline (NA), acetylcholine (ACh), and electrical field stimulation (EFS) of autonomic nerves were investigated. Nerve-mediated responses of the rabbit and human tunica albuginea were recorded. The EFS-induced human responses were completely abolished by prazosin. In the rabbit, EFS-induced contractile responses were reduced by pyridoxalphosphate-6-azophenyl-2',4'-disulphonic acid by 36% and by prazosin by 77%. Both antagonists together almost completely abolished all EFS-induced contractions. The human tunica albuginea was contracted by NA, ATP, and alpha, beta-methylene ATP, but not by ACh. The rabbit and rat tunica albuginea were contracted by NA, ATP, alpha, beta-methylene ATP, and ACh. The mouse tunica albuginea was contracted by ACh, ATP, and alpha, beta-methylene ATP, but relaxed to NA. Immunohistochemical studies showed that P2X1 (also known as P2RX1) and P2X2 (also known as P2RX2) receptors were expressed on the smooth muscle of the rodent testicular capsule, expression being less pronounced in man. The testicular capsule of the rat, mouse, rabbit, and man all contain contractile smooth muscle. ATP, released as a cotransmitter from sympathetic nerves, can stimulate the contraction of rabbit smooth muscle. Human, rat, and mouse testicular smooth muscle demonstrated purinergic responsiveness, probably mediated through the P2X1 and/or P2X2 receptors.     

Water and sodium transport: effects of calcium channel blocker and calmodulin antagonists on the apical and basolateral membranes of amphibian epithelia

Ca2+ channel blocker (sensit) and calmodulin antagonists (thioridazine, perphenazine, oxyprothepine) applied to the mucosal side of frog urinary bladder, weakened the response of epithelial cells to vasopressin. Thioridazine (2.7 X 10(-5) mol X l-1) and sensit (1.7 X 10(-4) mol X l-1) applied to the serosal side rapidly increased the permeability of the epithelia for sodium and potassium ions along the concentration gradient (from serosa to mucosa). The same concentrations of these blockers when applied to the mucosal side of frog urinary bladder selectively decreased vasopressin stimulated water permeability and did not influence ionic permeability. Both thioridazine and sensit decreased the short-circuit current across frog skin. The results show that the Ca2+ channel blocker and the calmodulin antagonists tested influenced water and ionic transport across the epithelial cell membranes, and had different effects upon the apical and the basolateral cell membranes.     

Atypical swimbladders of lake charr, Salvelinus namaycush, from Great Slave Lake, Northwest Territories, Canada

Swimbladder walls of lake charr, Salvelinus namaycush, from Great Slave Lake (GSL), Northwest Territories, Canada, were unusually thick for the species. The thinnest sections of the GSL bladders (mean = 2.44mm, range = 1.1–4.4mm) were significantly thicker (P = 0.001) than lake charr swimbladders collected from two small Province of Ontario lakes (means = 0.65 and 0.92mm), whose populations were assumed to be representative of the species. Variance in wall thickness was also greater in GSL lake charr than in charr from two small lakes (P < 0.02). Within individuals, some of the GSL bladder walls were markedly irregular in thickness, but whether these anomalies exist in situ or were artifacts of preservation remains uncertain. The bulk of the tissue in the thickest sections of the GSL swimbladders was in the tunica serosa (outer layer). The extent of the modification of the GSL swimbladders is extraordinary for northern fishes in postglacial lakes.     

Characterization of Schizosaccharomyces pombe mcm7(+) and cdc23(+) (MCM10) and interactions with replication checkpoints

MCM proteins are required for the proper regulation of DNA replication. We cloned fission yeast mcm7(+) and showed it is essential for viability; spores lacking mcm7(+) begin S phase later than wild-type cells and arrest with an apparent 2C DNA content. We isolated a novel temperature-sensitive allele, mcm7-98, and also characterized two temperature-sensitive alleles of the fission yeast homolog of MCM10, cdc23(+). mcm7-98 and both cdc23ts alleles arrest with damaged chromosomes and an S phase delay. We find that mcm7-98 is synthetically lethal with the other mcmts mutants but does not interact genetically with either cdc23ts allele. However, cdc23-M36 interacts with mcm4ts. Unlike other mcm mutants or cdc23, mcm7-98 is synthetically lethal with checkpoint mutants Deltacds1, Deltachk1, or Deltarad3, suggesting chromosomal defects even at permissive temperature. Mcm7p is a nuclear protein throughout the cell cycle, and its localization is dependent on the other MCM proteins. Our data suggest that the Mcm3p-Mcm5p dimer interacts with the Mcm4p-Mcm6p-Mcm7p core complex through Mcm7p.     

Light,electron microscopical,and immunocytochemical investigation of the stomach wall of the tigerfish Hydrocynus forskahlii

The wall of the stomach of the tigerfish is described and compared with that of other vertebrates. Light microscopic and ultrastructural characteristics of the stomach wall correspond to a large extent to those of other vertebrates, although some differences are found. The mucosa contains (1) surface epithelium characterized by narrow columnar cells with abundant mucous granules; (2) gastric glands consisting of pepsinogenic cells of variable height, containing tubulovesicles and bearing microvilli; (3) five granulated cell types located basally in the epithelium (types 1–5); and (4) lamina propria and muscularis mucosae. Connective tissue separating smooth muscle fibers of the muscularis mucosae constitutes a stratum compactum. The submucosa contains a loose connective tissue, a tunica muscularis of inner circular and outer longitudinal layers, and a serosa of mesothelium and subjacent connective tissue. Immunocytochemical tests with antisera to five polypeptides show gastrin/cholecystokinin (CCK), vasoactive intestinal polypeptide (VIP) immunoreactivities in some cells of the gastric glands, and somatostatin in cells lying among epithelial cells lining the gastric luminal surface or gastric pits.     

The Kluyveromyces lactis gamma-toxin targets tRNA anticodons

Kluyveromyces lactis killer strains secrete a heterotrimeric toxin (zymocin), which causes an irreversible growth arrest of sensitive yeast cells. Despite many efforts, the target(s) of the cytotoxic gamma-subunit of zymocin has remained elusive. Here we show that three tRNA species tRNA(Glu)(mcm(5)s(2)UUC), tRNA(Lys)(mcm(5)s(2)UUU), and tRNA(Gln)(mcm(5)s(2)UUG) are the targets of gamma-toxin. The toxin inhibits growth by cleaving these tRNAs at the 3' side of the modified wobble nucleoside 5-methoxycarbonylmethyl-2-thiouridine (mcm(5)s(2)U). Transfer RNA lacking a part of or the entire mcm(5) group is inefficiently cleaved by gamma-toxin, explaining the gamma-toxin resistance of the modification-deficient trm9, elp1-elp6, and kti11-kti13 mutants. The K. lactis gamma-toxin is the first eukaryotic toxin shown to target tRNA.     

A mutant that affects the function of autonomously replicating sequences in yeast

We previously reported the isolation of a series of mcm mutants that are defective in the maintenance of minichromosomes in yeast. These minichromosomes are circular plasmids, each containing an autonomously replicating sequence (ARS) and a centromere. One of the mcm mutants, mcm2, has the following phenotype: at room temperature it affects the stability of only some minichromosomes depending on the ARS present, while at high temperature it affects all minichromosomes tested irrespective of the ARS present. Here we show that the mcm defect as well as its temperature-dependent specificity for ARSs can be demonstrated with circular as well as linear plasmids that do not contain centromeric sequences. Larger chromosomes containing multiple ARSs are also unstable in this mutant. Further analyses indicate that the mcm2 mutation causes the loss, rather than the aberrant segregation, of the circular minichromosomes. In addition, this mutation appears to stimulate mitotic recombination frequencies. These properties of the mcm2 mutant are consistent with the idea that the mcm2 mutation results in a defect in the initiation of DNA replication at ARSs, the putative chromosomal replication origins in yeast.