Mouse Spermatozoa in High Concentrations of Glycerol: Chemical Toxicity vs Osmotic Shock at Normal and Reduced Oxygen Concentrations

Cryobiology ◽  
1998 ◽  
Vol 37 (4) ◽  
pp. 325-338 ◽  
Author(s):  
Igor I. Katkov ◽  
Nadezhda Katkova ◽  
John K. Critser ◽  
Peter Mazur
Keyword(s):  
Osmotic Shock ◽  
Chemical Toxicity ◽  
High Concentrations ◽  
Oxygen Concentrations

scholarly journals Isolation and Characterization of NaCl-Sensitive Mutants of Caulobacter crescentus

2003 ◽  
Vol 69 (6) ◽  
pp. 3029-3035 ◽  
Author(s):  
Luiz Fernando G. Zuleta ◽  
Val�ria C. S. Italiani ◽  
Marilis V. Marques
Keyword(s):  
Caulobacter Crescentus ◽  
Osmotic Shock ◽  
Promoter Regions ◽  
Isolation And Characterization ◽  
Lipopolysaccharide Biosynthesis ◽  
Severe Reduction ◽  
Mutant Strains ◽  
High Concentrations ◽  
Severe Growth

ABSTRACT An attempt to characterize Caulobacter crescentus genes important for the response to high concentrations of NaCl was initiated by the isolation of mutants defective in survival in the presence of 85 mM NaCl. A transposon Tn5 library was screened, and five strains which contained different genes disrupted by the transposon were isolated. Three of the mutants had the Tn5 in genes involved in lipopolysaccharide biosynthesis, one had the Tn5 in the nhaA gene, which encodes a Na+/H+ antiporter, and one had the Tn5 in the ppiD gene, which encodes a peptidyl-prolyl cis-trans isomerase. All the mutant strains showed severe growth arrest in the presence of 85 mM NaCl, but only the nhaA mutant showed decreased viability under these conditions. All the mutants except the nhaA mutant showed a slightly reduced viability in the presence of 40 mM KCl, but all the strains showed a more severe reduction in viability in the presence of 150 mM sucrose, suggesting that they are defective in responding to osmotic shock. The promoter regions of each disrupted gene were cloned in lacZ reporter vectors, and the pattern of expression in response to NaCl and sucrose was determined; this showed that both agents induced ppiD and nhaA gene expression but did not induce the other genes. Furthermore, the ppiD gene was not induced by heat shock, indicating that it does not belong to the σ32 regulon, as opposed to what was observed for its Escherichia coli homolog.

Oxygen recognition in aerotactic behaviour of Azospirillum brasilense Cd

1986 ◽  
Vol 32 (11) ◽  
pp. 829-834 ◽  
Author(s):  
Orly Reiner ◽  
Yaacov Okon
Keyword(s):  
Azospirillum Brasilense ◽  
Spectral Studies ◽  
Antimycin A ◽  
Terminal Oxidases ◽  
Cytochrome O ◽  
Low Concentrations ◽  
High Concentrations ◽  
Cytochrome D ◽  
Oxygen Concentrations

Oxygen recognition in aerotactic behaviour of Azospirillum brasilense was studied. Spectral studies of membrane preparations of A. brasilense Cd revealed three terminal oxidases: cytochromes aa3, o, and d. The possible involvement of each of these cytochromes in oxygen reception was evaluated. Since neither reducing the level of cytochrome aa3 in the bacteria nor inhibition of cytochrome aa3 by low concentrations of cyanide affected aerotaxis, it was concluded that cytochrome aa3 is not the oxygen receptor. Cytochromes o and d are inhibited by high concentrations of cyanide which also inhibit aerotaxis. Of these two, cytochrome o seems more likely to be the oxygen receptor, since antimycin A, which inhibits the reduction of this cytochrome (but not that of cytochrome d), completely inhibited aerotaxis. By using tethered cells, it was demonstrated that A. brasilense is microaerophilic, as it is attracted to oxygen concentrations lower than those present in the air (20%).

Zoospore Germination in Blastocladiella Emersonii

1972 ◽  
Vol 10 (2) ◽  
pp. 315-333
Author(s):  
D. R. SOLL ◽  
D. R. SONNEBORN
Keyword(s):  
Osmotic Shock ◽  
Cell Structure ◽  
Ion Selectivity ◽  
Choline Chloride ◽  
Exposure Period ◽  
Monovalent Cation ◽  
Continuous Exposure ◽  
Initial Exposure ◽  
Cell Conversion ◽  
High Concentrations

Zoospore germination in B. emersonii is accompanied by a series of abrupt, dramatic changes in cell structure. Membranes appear to be variously involved in many of these changes. Germination is subject to simple manipulations of the ionic environment: swimming zoospores can be maintained for long periods in the buffered CaCl2 solution into which they are initially released, whereas dilution into a solution containing KCl and MgCl2 in addition to CaCl2 results in rapid, semisynchronous germination of entire zoospore populations. The control of germination by ionic means has been characterized in the following ways: (a) Very brief (40 S to 2 min) exposure to GS, followed by replacement with buffered CaCl2 is as effective as continuous exposure in eliciting rapid germination of the entire zoospore population. (b) The effective component of GS is KCl: GS lacking KCl does not elicit rapid germination; conversely, buffered KCl alone is as effective as complete GS in eliciting germination. (c) Zoospore populations are sensitive to KCl concentration; as the KCl concentration is reduced, the proportion of cells which undergo rapid germination is also reduced. (d) At optimal concentration (5 x 10-2 M), the following salts are equally as effective as KCl in eliciting germination: KI, KBr, NaCl, CsCl, RbCl, and choline chloride. (e) At high concentrations (2.5-5 x 10-2 M), CaCl2 and MgCl2 elicit semi-synchronous conversion of zoospores to round cells, but only after sizeable delays (v. KCl). Conversion of round cells to germlings does not occur in MgCl2 and is enormously delayed in CaCl2; when formed, the germ tubes appear abnormal. (f) Monovalent cation salts of complex divalent anions (sulphate, tartrate, molybdate, tungstate) also exhibit decreased effectiveness (v. KCl) in eliciting germination. (g) The monovalent cation salts NH4Cl and LiCl, the divalent cation salt MnCl2, and the non-ionic compound sucrose are all ineffective in eliciting rapid germination. When in combination with an effective elicitor (KCl), LiCl totally blocks germination, MnCl2 and sucrose lead to significant delays in zoospore to round cell conversion, while NH4Cl has no effect on the population kinetics. (h) LiCl can block germination even when added after the completion of the otherwise sufficient early exposure period to GS (see (a) above). The blocking effect of LiCl can be almost completely reversed by replacement with KCl. On the basis of this characterization it is concluded that (1) rapid germination is not elicited simply by osmotic shock; rather, the cells are capable of responding to other (especially ionic) properties of their chemical environment; and (2) while brief exposure to KCl is sufficient to elicit germination, there are evidently other ion-sensitive steps occurring after the completion of this initial exposure period. Implications of the results in relation to the regular ion selectivity patterns found in other ion-dependent systems, the possible site(s) of action of the eliciting compounds, and the newly discovered ‘zoospore maintenance factor’ are discussed.

UM ENSAIO SOBRE A ADAPTAÇÃO DE Pygocentrus nattereri À VARIAÇÃO SAZONAL DAS ÁGUAS DO LAGO MAMIRAUÁ – RESERVA DE DESENVOLVIMENTO SUSTENTÁVEL MAMIRAUÁ

2008 ◽  
Vol 1 (1) ◽  
pp. 65-70
Author(s):  
Mauricio Camargo ◽  
Helder Queiroz
Keyword(s):  
Sustainable Development ◽  
Habitat Use ◽  
Low Oxygen ◽  
Vital Functions ◽  
Pygocentrus Nattereri ◽  
High Concentrations ◽  
Concentration Levels ◽  
Flooding Period ◽  
Oxygen Concentrations

This study investigates habitat use of Pygocentrus nattereri Kner, 1858 at the highest m om ents of the flooding period (July) and during the low water period (October), and evaluates the hability to survive low oxygen concentrations and the production of sulphidric gas in the waters of Mamirauá Lake – Mamirauá Sustainable Development Reserve. 12 experimental samplings were taken at six sites in Mamirauá Lake, and at Paraná Apara. With two experiments, carried out inside the waterbodies and in aquarium , we evaluated the effect of low D.O. concentration levels in the water on P. nattereri. Results show that even under restraining conditions of oxygenation in the water, P. nattereri are able to keep their vital functions. Different situation is observed when the waters of Mamirauá Lake produce high concentrations of suphidric gas, and the individuals of P. nattereri die under this circunstance.

scholarly journals Selective Osmotic Shock for Islet Isolation in the Cadaveric Canine Pancreas

2018 ◽  
Vol 27 (3) ◽  
pp. 542-550
Author(s):  
Elizabeth M. Thompson ◽  
Jennifer L. Sollinger ◽  
Emmanuel C. Opara ◽  
Christopher A. Adin
Keyword(s):  
Glucose Transporter ◽  
Osmotic Shock ◽  
Stimulation Index ◽  
Gradient Centrifugation ◽  
Treatment Protocol ◽  
Islet Isolation ◽  
Group 4 ◽  
High Concentrations ◽  
Group 2 ◽  
Islet Physiology

Currently, islet isolation is performed using harsh collagenases that cause nonspecific injury to both islets and exocrine tissue, negatively affecting the outcome of cell transplantation. We evaluated a novel islet isolation protocol utilizing high concentrations of glucose to cause selective osmotic shock (SOS). Islets have a membrane glucose transporter that allows adaptation to changes in glucose concentrations while exocrine tissue can be selectively destroyed by these osmolar shifts. Canine pancreata were obtained within 15 min after euthanasia from animals ( n = 6) euthanized for reasons unrelated to this study. Each pancreas was divided into 4 segments that were randomized to receive 300 mOsm glucose for 20 min (group 1), 600 mOsm for 20 min (group 2), 300 mOsm for 40 min (group 3), or 600 mOsm for 40 min (group 4). Islet yield, purity, and viability were compared between groups. Mean ± standard error of the mean islet yield for groups 1 to 4 was 428 ± 159, 560 ± 257, 878 ± 443, and 990 ± 394 islet equivalents per gram, respectively. Purity ranged from 37% to 45% without the use of density gradient centrifugation and was not significantly different between groups. Islet cell viability was excellent overall (89%) and did not differ between treatment protocol. Islet function was best in groups treated with 300 mOsm of glucose (stimulation index [SI] = 3.3), suggesting that the lower concentration of glucose may be preferred for use in canine islet isolation. SOS provides a widely available means for researchers to isolate canine islets for use in islet transplantation or in studies of canine islet physiology.

Effect of Oxygen on Development of Off-Flavors in Ultrahigh-Temperature Milk1

1985 ◽  
Vol 48 (6) ◽  
pp. 487-493 ◽  
Author(s):  
K. D. WADSWORTH ◽  
R. BASSETTE
Keyword(s):  
Dissolved Oxygen ◽  
Storage Period ◽  
Thiobarbituric Acid ◽  
Prolonged Storage ◽  
Two Samples ◽  
Off Flavors ◽  
Flavor Development ◽  
High Concentrations ◽  
Kansas State University ◽  
Oxygen Concentrations

The role of dissolved oxygen as a contributor to flavor deterioration in sterile milk during storage was investigated. Before processing, a concentrated aqueous solution of Tenox-2 was added to half of a batch of pasteurized-homogenized milk to give a final concentration of 400 ppm BHA on a fat basis in the milk. The other half was untreated. Half of each of those batches was treated to reduce oxygen concentrations by a combination of nitrogen sweep and sonication. The remaining two samples (Tenox-2 added and no-Tenox-2) did not receive the deoxygenation treatment. Oxygen levels in the preprocessed deoxygenated milk were lower (4.6 ppm) than those in the untreated milk (6.9 ppm). All four lots were UHT-sterilized at 135°C for 5 s in an indirect UHT system constructed at Kansas State University. Sterilized milk was collected aseptically in a glove box in 250-ml amber glass bottles, which were closed with either Teflon-lined caps or sterile cotton plugs. Samples from each treatment were stored at 7° and 32°C for 4 months. Samples in capped bottles maintained relatively low (<4 ppm) dissolved oxygen concentrations, whereas those in cotton-plugged bottles had relatively high (7–7.5 ppm) dissolved oxygen concentrations. Dissolved oxygen affected the rate of stale flavor development. Sterile milk in bottles with cotton plugs, which had relatively high concentrations of dissolved oxygen during storage, developed a stale flavor sooner and with greater intensity than milks with lower levels of oxygen. However, acetaldehyde, propanal, n-pentanal, and n-hexanal, which are most likely products of lipid oxidation, did not appear to be principal contributors to staling in sterile milk during storage in this study. Furthermore, the stale flavor development did not parallel changes in thiobarbituric acid (TBA) values. Although antioxidant (40 ppm BHA on fat basis from Tenox-2) did retard oxidation slightly, it did not control staling. A decrease in the concentration of several volatile materials throughout the storage period probably was caused by dissipation of the volatile material through the cotton plug or by their interaction with other compounds in the milk. Acid degree values increased in sterile milk at 32°C during prolonged storage, but changes in ADVs did not parallel development of the stale flavor.

Freeze-fracture, freeze-etch complementary pairs of virus-infected cells reveal value of etching even when relatively high concentrations of cryoprotectants are used

1978 ◽  
Vol 36 (2) ◽  
pp. 136-137
Author(s):  
Russell L. Steere ◽  
Eric F. Erbe
Keyword(s):  
Plant Tissue ◽  
Phosphate Buffer ◽  
Infected Plant ◽  
Freeze Fracture ◽  
Distilled Water ◽  
Virus Infected Plant ◽  
Infected Cells ◽  
High Concentrations

It has been assumed by many involved in freeze-etch or freeze-fracture studies that it would be useless to etch specimens which were cryoprotected by more than 15% glycerol. We presumed that the amount of cryoprotective material exposed at the surface would serve as a contaminating layer and prevent the visualization of fine details. Recent unexpected freeze-etch results indicated that it would be useful to compare complementary replicas in which one-half of the frozen-fractured specimen would be shadowed and replicated immediately after fracturing whereas the complement would be etched at -98°C for 1 to 10 minutes before being shadowed and replicated.Standard complementary replica holders (Steere, 1973) with hinges removed were used for this study. Specimens consisting of unfixed virus-infected plant tissue infiltrated with 0.05 M phosphate buffer or distilled water were used without cryoprotectant. Some were permitted to settle through gradients to the desired concentrations of different cryoprotectants.

Properties of Isolated Mitochondria of Agaricus Bisporus: Their Relationship to Dormancy and the Germination of Spores

1973 ◽  
Vol 31 ◽  
pp. 458-459
Author(s):  
K. S. McCarty ◽  
R. F. Weave ◽  
L. Kemper ◽  
F. S. Vogel
Keyword(s):  
Mitochondrial Dna ◽  
Ethidium Bromide ◽  
Microscopic Examination ◽  
Agaricus Bisporus ◽  
Osmotic Shock ◽  
Electron Microscopic Examination ◽  
Electron Microscopic ◽  
Isolated Mitochondria ◽  
Dna Strands ◽  
Cytoplasmic Ribosomes

During the prodromal stages of sporulation in the Basidiomycete, Agaricus bisporus, mitochondria accumulate in the basidial cells, zygotes, in the gill tissues prior to entry of these mitochondria, together with two haploid nuclei and cytoplasmic ribosomes, into the exospores. The mitochondria contain prominent loci of DNA [Fig. 1]. A modified Kleinschmidt spread technique1 has been used to evaluate the DNA strands from purified whole mitochondria released by osmotic shock, mitochondrial DNA purified on CsCl gradients [density = 1.698 gms/cc], and DNA purified on ethidium bromide CsCl gradients. The DNA appeared as linear strands up to 25 u in length and circular forms 2.2-5.2 u in circumference. In specimens prepared by osmotic shock, many strands of DNA are apparently attached to membrane fragments [Fig. 2]. When mitochondria were ruptured in hypotonic sucrose and then fixed in glutaraldehyde, the ribosomes were released for electron microscopic examination.

Effect of verapamil on cytoplasmic distribution of granules and microfilaments in amphibian urinary bladder

1988 ◽  
Vol 46 ◽  
pp. 324-325
Author(s):  
A.J. Mia ◽  
L.X. Oakford ◽  
T. Yorio
Keyword(s):  
Urinary Bladder ◽  
Water Flow ◽  
Morphological Changes ◽  
Granular Cell ◽  
Cytosolic Calcium ◽  
Calcium Storage ◽  
Amphibian Urinary Bladder ◽  
Vesicular Membrane ◽  
High Concentrations ◽  
Cytoskeletal System

The amphibian urinary bladder has been used as a ‘model’ system for studies of the mechanism of action of antidiuretic hormone (ADH) in stimulating transepithelial water flow. The increase in water permeability is accompanied by morphological changes that include the stimulation of apical microvilli, mobilization of microtubules and microfilaments and vesicular membrane fusion events . It has been shown that alterations in the cytosolic calcium concentrations can inhibit ADH transmembrane water flow and induce alterations in the epithelial cell cytomorphology, including the cytoskeletal system . Recently, the subapical granules of the granular cell in the amphibian urinary bladder have been shown to contain high concentrations of calcium, and it was suggested that these cytoplasmic constituents may act as calcium storage sites for intracellular calcium homeostasis. The present study utilizes the calcium antagonist, verapamil, to examine the effect of calcium deprivation on the cytomorphological features of epithelial cells from amphibian urinary bladder, with particular emphasis on subapical granule and microfilament distribution.

Sign in / Sign up

Export Citation Format

Share Document