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At least 19 recordsLinked to original sources
PubMed1986

Fine structure of gels prepared from an actin-binding protein and actin: comparison to cytoplasmic extracts and cortical cytoplasm in amoeboid cells of cortical cytoplasm in amoeboid cells of Dictyostelium discoideum.

We have identified the three-dimensional ultrastructure of actin gels that are formed in well-characterized cell extracts and mixtures of purified actin and the 120K actin-binding protein and compared these to the ultrastructure of the cytoplasmic matrix in regions of nonextracted Dictyostelium amoebae that are rich in actin and 120K. This ultrastructural characterization was achieved by using critical-point-dried whole-mount preparations. All three preparations--gelled extracts, purified proteins, and cortical cytoplasm--are composed of filament networks. The basic morphological feature of these networks is the presence of contacts between convergent filaments resulting in "T" or "X" shaped contacts. The finding that actin-containing gels are composed of filament networks, where the primary interaction occurs between convergent filaments, reconciles the known requirement of F actin for gelation with the amorphous appearance of these gels in thin sections. Increasing the molar ratio of 120K dimer to actin monomer increases the number of contacts between filaments per unit volume and decreases the lengths of filaments between contacts. This indicates that 120K stabilizes interactions between filaments and is consistent with biochemical evidence that 120K crosslinks actin filaments. The cortical network in situ resembles more closely networks formed in 120K-rich extracts than networks assembled in mixtures of purified 120K and actin. The heterogeneity of filament diameters and variation of network density are properties shared by extracts and the cytomatrix in situ while networks found in purified 120K-actin gels have filament diameters and densities that are more uniform. These differences are certainly due to the more complex composition of cell extracts and cortical cytoplasm as compared to that of purified 120K-actin gels.

Actins↗
PubMed1994

The clinical and pathological spectrum of antineutrophil cytoplasmic autoantibody-related pulmonary disease. A comparison between perinuclear and cytoplasmic antineutrophil cytoplasmic autoantibodies.

Antineutrophil cytoplasmic autoantibodies (ANCAs), classified as either perinuclear (P-ANCAs) or cytoplasmic (C-ANCAs), have been recently recognized as important markers for the diagnosis and monitoring of systemic vasculitic disorders. The purpose of this study was to review retrospectively the clinical and pathological features in patients with P-ANCA-positive (P-ANCA+) patterns and pulmonary disease who underwent open lung biopsies and to contrast these findings with those found in patients with C-ANCA-positive (C-ANCA+) patterns who underwent open lung biopsies. Nine patients with ANCA+ pattern (five with P-ANCA+ and four with C-ANCA+ patterns) who had evidence of systemic vasculitis and pulmonary dysfunction underwent open lung biopsies. A comparison of the clinical presentation in patients with P-ANCA+ vs C-ANCA+ patterns showed few apparent differences in the clinical presentation or in the organ involvement. Histologic review of the findings from the open lung biopsies showed similar patterns of pulmonary injury, irrespective of the specific ANCA-staining pattern. Major pathologic changes included intra-alveolar hemorrhage (four patients with P-ANCA+ patterns vs three patients with C-ANCA+ patterns), necrotizing capillaritis (four patients with P-ANCA+ patterns vs three patients with C-ANCA+ patterns), vasculitis (three patients with P-ANCA+ patterns vs two patients with C-ANCA+ patterns), and necrotizing granulomatous inflammation (two patients with P-ANCA+ patterns vs one patient with C-ANCA+ patterns). Unusual pathologic findings included chronic interstitial fibrosis (two patients with P-ANCA+ patterns vs two patients with C-ANCA+ patterns), cavitary nodules with necrotic neutrophils and minimal granulomatous inflammation (one patient with P-ANCA+ patterns), and bronchiolocentric granulomatous inflammation (one patient with P-ANCA+ patterns vs one patient with C-ANCA+ patterns). In ANCA-related pulmonary disease, there are few significant clinical or pathological differences when patients with P-ANCA+ patterns are compared with patients with C-ANCA+ patterns.

Adult↗
PubMed1988

Spermiogenesis in the red-ear turtle (Pseudemys scripta) and the domestic fowl (Gallus domesticus): a study of cytoplasmic events including cell volume changes and cytoplasmic elimination.

Nuclear and cytoplasmic volume changes as well as the elimination of residual spermatid cytoplasm were investigated in the red-ear turtle (Pseudemys scripta) and the rooster (Gallus domesticus). Nuclei of newly formed spermatids which were originally centrally located became eccentrically located within the cell in both species. Shortly thereafter the nuclear pole of the spermatid was found situated within deep crypts of a Sertoli cell. The cytoplasm of elongating spermatids was displaced along the nonacrosomal region of the nucleus and the proximal flagellum. In both species sheetlike Sertoli cell processes indented spermatid cytoplasm adjacent to the nucleus and appeared to segregate small packets of the cytoplasm. In the turtle, these packets of cytoplasm were separated from the spermatid. In both the turtle and rooster, a portion of the spermatid cytoplasm was displaced forward over the acrosomal region of the spermatid to resemble a hood. As spermatids were transported to the seminiferous tubular lumen, cytoplasmic lobes which projected forward of the spermatid head were formed by preferential flow of cytoplasm into one aspect of the cytoplasmic hood. In both species, at sperm release the cytoplasmic lobe was disengaged from the spermatid head to form a large residual body that was internalized and degraded within the Sertoli cell. Medium-sized cytoplasmic lobes were pinched from the head and neck region of the turtle and rooster spermatids, respectively. In the turtle, small-sized mitochondrial-rich cytoplasmic fragments budded from the caudal head and midpiece of the spermatids and were phagocytosed by the Sertoli cell. Thus, cytoplasmic elimination occurred through 1) segregation of cytoplasmic packets by Sertoli penetrating processes (turtle), 2) elimination of large and medium-sized residual bodies from the head (turtle and bird), and 3) budding of small mitochondrial-rich cytoplasmic fragments from the region of the midpiece (turtle). In the turtle a 79% reduction in total cell volume occurred during spermiogenesis which was the result of an 84% cytoplasmic reduction and a 78% nuclear reduction. During spermiogenesis, the rooster lost 97% of its total cell volume due to a 97% cytoplasmic volume change and a 96% nuclear volume change.

Animals↗
PubMed2001

H+-ATPase-mediated cytoplasmic pH-responses associated with elevation of cytoplasmic calcium in cultured rabbit nonpigmented ciliary epithelium.

Studies were conducted to test whether an increase of cytoplasmic calcium concentration influences H+-ATPase activity in cultured rabbit nonpigmented ciliary epithelium (NPE). Cytoplasmic calcium concentration or cytoplasmic pH was measured by a fluorescence ratio technique in cells loaded with either Fura-2 or BCECF. Cytoplasmic calcium was increased in three ways; by exposure to BAY K 8644 (1 microm), by exposure to a mixture of epinephrine (1 microm) + acetylcholine (10 microm) or by depolarization with potassium-rich solution. In each case cytoplasmic pH increased significantly. In all three cases 100 nm bafilomycin A1, a specific H+-ATPase inhibitor, significantly inhibited the pH increase. These results suggest an increase of cytoplasmic calcium might initiate events that lead to activation of proton export from the cytoplasm by a mechanism involving H+-ATPase. This notion is supported by the observation that the pH increase was suppressed when either verapamil or nifedipine was used to prevent the cytoplasmic calcium increase in cells exposed to potassium-rich solution. Protein kinase C activation might also be involved in the mechanism of H+-ATPase stimulation since staurosporine suppressed the pH response to potassium-rich solution. A transient rise of cytoplasmic calcium concentration was observed when cytoplasmic acidification was induced by exposure to high pCO2. This suggests a rise of cytoplasmic calcium might represent part of a physiological mechanism to stimulate H+-ATPase-mediated protein export under acid conditions.

3-Pyridinecarboxylic acid, 1,4-dihydro-2,6-dimethy↗
PubMed1993

Neutrophil alloantibodies react with cytoplasmic antigens: a possible cause of false-positive indirect immunofluorescence assays for antibodies to neutrophil cytoplasmic antigens.

Antibodies to neutrophil cytoplasmic antigens (ANCA) can be detected in patients with Wegener's granulomatosis and systemic vasculitis. During pregnancy or following transfusion, subjects sometimes produce alloantibodies to neutrophil antigens. If patient sera being tested for ANCA contain alloantibodies directed at neutrophil antigens that residue in the cytoplasm, the results may be difficult to interpret. At least one neutrophil antigen, NB1, is expressed on both neutrophil plasma membranes and secondary granules. We tested alloantibodies specific for neutrophil antigens NA1, NA2, NB1, NB2, 5b, 9a, and Mart in an ANCA-indirect immunofluorescence (ANCA-IF) assay to determine if these alloantibodies reacted with neutrophil cytoplasmic or granule antigens. Alloantibodies specific for neutrophil antigens NA1, NA2, NB2, 5b, and 9a did not react with neutrophil cytoplasmic components. However, all three NB1 alloantibodies studied demonstrated a cytoplasmic pattern of immunofluorescence (C-ANCA) when NB1-positive neutrophils were tested. While control ANCA resulted in cytoplasmic immunofluorescence of all neutrophils from each donor tested, NB1 antibodies reacted with a subpopulation of neutrophils from some donors. Cytoplasmic immunofluorescence was also observed with an antibody directed against the Mart neutrophil antigen. The Mart antigen is located on integrin CR3 (CD11b/CD18). To confirm that these reactions were due to anti-Mart, monoclonal antibodies to CD11b and CD18 were also tested and found to cause cytoplasmic immunofluorescence. When the ANCA-IF assay was performed using neutrophils that did not express Mart or NB1 antigen, cytoplasmic immunofluorescence was seen with the ANCA control antisera, but not with the NB1 or Mart alloantibodies.(ABSTRACT TRUNCATED AT 250 WORDS)

Antibodies, Antineutrophil Cytoplasmic↗
PubMed1988

Spermiogenesis in the bullfrog (Rana catesbeiana): a study of cytoplasmic events including cell volume changes and cytoplasmic elimination.

The process by which spermatid cytoplasmic volume is reduced and cytoplasm eliminated during spermiogenesis was investigated in the bullfrog Rana catesbeiana. At early phases of spermiogenesis, newly formed, rounded spermatids were found within spermatocysts. As acrosomal development, nuclear elongation, and chromatin condensation occurred, spermatid nuclei became eccentric within the cell. A cytoplasmic lobe formed from the caudal spermatid head and flagellum and extended toward the seminiferous tubule lumen. The cytoplasmic lobe underwent progressive condensation whereby most of its cytoplasm became extremely electron dense and contrasted sharply with numerous electron-translucent vesicles contained therein. At the completion of spermiogenesis, many spermatids with their highly condensed cytoplasm still attached were released from their Sertoli cell into the lumen of the seminiferous tubule. There was no evidence of the phagocytosis of residual bodies by Sertoli cells. Because spermatozoa are normally retained in the testis in winter and are not released until the following breeding season, sperm were induced to traverse the duct system with a single injection of hCG. Some spermatids remained attached to their cytoplasm during the sojourn through the testicular and kidney ducts; however, by the time the sperm reached the Wolffian duct, separation had occurred. The discarded cytoplasmic lobe (residual body) appeared to be degraded with the epithelium of the Wolffian duct. It was determined that the volume of the spermatid was reduced by 87% during spermiogenesis through a nuclear volume decrease of 76% and cytoplasmic volume decrease of 95.3%.

Animals↗
PubMed1996

The CMS-associated 16 kDa protein encoded by orfH522 in the PET1 cytoplasm is also present in other male-sterile cytoplasms of sunflower.

In sunflower plants carrying the PET1 cytoplasm male sterility (CMS) is associated with a new open reading frame (orfH522) in the 3'-flanking region of the atpA gene and an additional 16 kDa protein. Twenty-seven male-sterile cytoplasms of different origin were studied for the expression of the 16 kDa protein. In addition to the PET1 cytoplasm nine other male-sterile cytoplasms express the CMS-associated protein. These CMS sources originate from different interspecific crosses, from spontaneously occurring male-sterile plants in wild sunflower and from induced mutagenesis. Polyclonal antisera were raised against fusion proteins which contain 421 bp of the 3'-coding region of orfH522 to verify by immunological methods the identity of the other CMS cytoplasms. The anti-ORFH522 antiserum showed a positive reaction in the immunoblot with all CMS cytoplasms which expressing the 16 kDa protein. Investigations of the mitochondrial DNA demonstrated that all ten CMS cytoplasms which express the 16 kDa protein have the same organization at the atpA locus. OrfH522 as probes gave the same transcript pattern for the investigated CMS cytoplasms, just as for PET1. The MAX1 cytoplasm has an orfH522-related sequence but does not synthesize the 16 kDa protein. Using the sodium carbonate treatment the 16 kDa protein proved to be membrane-bound. Computer analyses predict that the hydrophobic N-terminal region of ORFH522 may form a transmembrane helix functioning as membrane anchor.

Cytoplasm↗
PubMed1975

Cytoplasmic membrane vesicles of Escherichia coli. A simple method for preparing the cytoplasmic and outer membranes.

A simple preparative method is described for isolation of the cytoplasmic and outer membranes from E. coli. The characteristics of both membrane fractions were studied chemically, biologically, and morphologically. Spheroplasts of E. coli K-12 strain W3092, prepared by treating cells with EDTA-lysozyme [EC 3.2.1.17], were disrupted in a French press. The crude membrane fraction was washed with 3 mM EDTA-10% (w/v) sucrose, pH 7.2, and the cytoplasmic membranes and outer membranes were separated by sucrose isopycnic density gradient centrifugation. The crude membrane fraction contained approximately 10% of the protein of the whole cells, 0.3% of the DNA, 0.7% of the RNA, 0.3% of the peptidoglycan, and about 30% of the lipopolysaccharide. The cytoplasmic membrane fraction was rich in phospholipid, while the outer membrane fraction contained much lipopolysaccharide and carbohydrate; the relative contents of lipopolysaccharide and carbohydrate per mg protein in the cytoplasmic membrane fraction were 12 and 40%, respectively, of the contents in the outer membrane fraction. Cytochrome b1, NADH oxidase, D-lactate dehydrogenase [EC 1.1.1.28], succinate dehydrogenase [EC 1.3.99.1], ATPase [EC 3.5.1.3], and activity for concentrative uptake of proline were found to be localized mainly in the cytoplasmic membranes; their specific activities in the outer membrane fraction were 1.5 to 3% of those in the cytoplasmic membrane fraction. In contrast, a phospholipase A appeared to be localized mainly in the outer membranes and its specific activity in the cytoplasmic membrane fraction was only 5% of that in the outer membrane fraction. The cytoplasmic and outer membrane fractions both appeared homogeneous in size and shape and show vesicular structures by electron microscopy. The advantages of this method for large scale preparation of the cytoplasmic and outer membrane fractions are discussed.

Adenosine Triphosphatases↗
PubMed1986

Cytoplasmic domains of cellular and viral integral membrane proteins substitute for the cytoplasmic domain of the vesicular stomatitis virus glycoprotein in transport to the plasma membrane.

Oligonucleotide-directed mutagenesis was used to construct chimeric cDNAs that encode the extracellular and transmembrane domains of the vesicular stomatitis virus glycoprotein (G) linked to the cytoplasmic domain of either the immunoglobulin mu membrane heavy chain, the hemagglutinin glycoprotein of influenza virus, or the small glycoprotein (p23) of infectious bronchitis virus. Biochemical analyses and immunofluorescence microscopy demonstrated that these hybrid genes were correctly expressed in eukaryotic cells and that the hybrid proteins were transported to the plasma membrane. The rate of transport to the Golgi complex of G protein with an immunoglobulin mu membrane cytoplasmic domain was approximately sixfold slower than G protein with its normal cytoplasmic domain. However, this rate was virtually identical to the rate of transport of micron heavy chain molecules measured in the B cell line WEHI 231. The rate of transport of G protein with a hemagglutinin cytoplasmic domain was threefold slower than wild type G protein and G protein with a p23 cytoplasmic domain, which were transported at similar rates. The combined results underscore the importance of the amino acid sequence in the cytoplasmic domain for efficient transport of G protein to the cell surface. Also, normal cytoplasmic domains from other transmembrane glycoproteins can substitute for the G protein cytoplasmic domain in transport of G protein to the plasma membrane. The method of constructing precise hybrid proteins described here will be useful in defining functions of specific domains of viral and cellular integral membrane proteins.

B-Lymphocytes↗
PubMed2003

Examination of the cytoplasmic DNA in male reproductive cells to determine the potential for cytoplasmic inheritance in 295 angiosperm species.

Mature pollen grains of 295 angiosperm species were screened by epifluorescence microscopy for a marker that denotes the mode of cytoplasmic inheritance. We used the DNA fluorochrome DAPI (4',6-diamidino-2-phenylindole) for pollen cell staining. The presence or absence of fluorescence of cytoplasmic DNA in the generative cell or sperm cells was examined in each species. The species examined represented 254 genera and 98 families, and 40 of these families had not been previously studied in this regard. The cytoplasmic DNA of the generative cell or sperm cells did not fluoresce in 81% of the species examined, from 83% of the genera and 87% of the families examined, indicating the potential for maternal cytoplasmic inheritance in these species. In contrast, the male reproductive cells of 19% of the species, from 17% of the genera and 26% of the families examined, displayed fluorescence of the cytoplasmic DNA, indicating the potential for biparental cytoplasmic inheritance in these species. The results revealed the potential for biparental cytoplasmic inheritance in several species in which the inheritance mode was previously unknown, including plants in the Bignoniaceae, Cornaceae, Cruciferae (Brassicaceae), Cyperaceae, Dipsacaceae, Hydrocharitaceae, Papaveraceae, Portulacaceae, Tiliaceae, Valerianaceae, and Zingiberaceae. Electron microscopy revealed that the sperm cells of Portulaca grandiflora contain both plastid and mitochondrial DNA. However, in the generative cells of Musella lasiocarpa, the mitochondria contain DNA, but the plastids do not. These data provide a foundation for further studies of cytoplasmic inheritance in angiosperms.

Cytoplasm↗
PubMed1994

Further analysis of cytoplasmic polyadenylation in Xenopus embryos and identification of embryonic cytoplasmic polyadenylation element-binding proteins.

Early development in Xenopus laevis is programmed in part by maternally inherited mRNAs that are synthesized and stored in the growing oocyte. During oocyte maturation, several of these messages are translationally activated by poly(A) elongation, which in turn is regulated by two cis elements in the 3' untranslated region, the hexanucleotide AAUAAA and a cytoplasmic polyadenylation element (CPE) consisting of UUUUUAU or similar sequence. In the early embryo, a different set of maternal mRNAs is translationally activated. We have shown previously that one of these, C12, requires a CPE consisting of at least 12 uridine residues, in addition to the hexanucleotide, for its cytoplasmic polyadenylation and subsequent translation (R. Simon, J.-P. Tassan, and J.D. Richter, Genes Dev. 6:2580-2591, 1992). To assess whether this embryonic CPE functions in other maternal mRNAs, we have chosen Cl1 RNA, which is known to be polyadenylated during early embryogenesis (J. Paris, B. Osborne, A. Couturier, R. LeGuellec, and M. Philippe, Gene 72:169-176, 1988). Wild-type as well as mutated versions of Cl1 RNA were injected into fertilized eggs and were analyzed for cytoplasmic polyadenylation at times up to the gastrula stage. This RNA also required a poly(U) CPE for cytoplasmic polyadenylation in embryos, but in this case the CPE consisted of 18 uridine residues. In addition, the timing and extent of cytoplasmic poly(A) elongation during early embryogenesis were dependent upon the distance between the CPE and the hexanucleotide. Further, as was the case with Cl2 RNA, Cl1 RNA contains a large masking element that prevents premature cytoplasmic polyadenylation during oocyte maturation. To examine the factors that may be involved in the cytoplasmic polyadenylation of both C12 and C11 RNAs, we performed UV cross-linking experiments in egg extracts. Two proteins with sizes of ~36 and ~45 kDa interacted specifically with the CPEs of both RNAs, although they bound preferentially to the C12 CPE. The role that these proteins might play in cytoplasmic polyadenylation is discussed.

Age Factors↗
PubMed1993

Human immunodeficiency virus type 1 Vpu protein induces degradation of chimeric envelope glycoproteins bearing the cytoplasmic and anchor domains of CD4: role of the cytoplasmic domain in Vpu-induced degradation in the endoplasmic reticulum.

The human immunodeficiency virus type 1 (HIV-1) Vpu protein is a transmembrane phosphoprotein which induces rapid degradation of CD4 in the endoplasmic reticulum (ER). To identify sequences in CD4 for Vpu-induced degradation, we generated four chimeric envelope glycoproteins having the ectodomain of HIV-1 gp160, the anchor domain of CD4, and 38, 25, 24, and 18 amino acids (aa) of the CD4 cytoplasmic domain. Using the vaccinia virus-T7 RNA polymerase expression system, we analyzed the expression of chimeric proteins in the presence and absence of Vpu. In singly transfected cells, the chimeric envelope glycoproteins having 38, 24, and 18 aa of the CD4 cytoplasmic domain were endoproteolytically cleaved and biologically active in the fusion of HeLa CD4+ cells. However, one of the chimeras having 25 aa of the CD4 cytoplasmic tail was retained in the ER using the transmembrane ER retention signal and was defective in membrane fusion. Furthermore, biochemical analyses of the coexpressing cells revealed that the Vpu protein induced degradation of the envelope glycoproteins having 38, 25, and 24 aa of the CD4 cytoplasmic tail and degradation occurred in the ER. Consequently, the fusion-competent glycoproteins did not induce the formation of syncytia in HeLa CD4+ cells expressing Vpu. However, the HIV-1 gp160 and chimeric envelope glycoprotein having the membrane-proximal 18 aa of the CD4 cytoplasmic tail were stable and fusion competent in cells expressing Vpu. In addition, we examined the stability of CD4 molecules in the presence of Vpu. Coexpression analyses revealed that the Vpu protein induced degradation of CD4 whereas mutant CD4 having the membrane-proximal 18 aa of the cytoplasmic domain was relatively stable in the presence of Vpu. Taken together, these studies have elucidated that the Vpu protein requires sequences or sequence determinants in the cytoplasmic domain of CD4 to induce degradation of the glycoproteins in the cell.

Amino Acid Sequence↗
PubMed1979

The ultrastructure of the dorsal yolk-free cytoplasm and the immediately surrounding cytoplasm in the symmetrized egg of Xenopus laevis.

Cytoplasmic segregation and subsequent dorsad displacement of the segregated cytoplasm lead to symmetrization of the egg of Xenopus laevis. At 60 min post-fertilization (p.f.) the 'dorsal yolk-free cytoplasm' (DYFC) is located in the dorso-animal part of the egg. Its ultrastructure and that of the immediately surrounding cytoplasm have been studied with transmission electron microscopy (TEM). The endoplasmic reticulum (ER) within the DYFC consists of single or paired cisternae and many small vesicles, both with moderately dense contents. Numerous particles, presumably ribosomes and glycogen, are present together with many mitochondria and some Golgi structures. The fraction of total yolk-free area occupied by mitochondria in the DYFC is about three times that in the adjacent cytoplasm. The number of cytoplasmic vesicles per unit area of cytoplasm is far larger in the DYFC than in the surrounding area. The morphological characteristics of the DYFC at 60 min p.f. suggest that it represents a region of high metabolic activity. Since it is located in the dorso-animal quadrant of the uncleaved egg, it may be partly responsible for a difference in metabolism between the dorsal and the ventral side of the egg, and hence may play an essential role in the determination of dorso-ventrality.

Animals↗
PubMedDate not supplied

Development of an image analysis system to monitor the retention of residual cytoplasm by human spermatozoa: correlation with biochemical markers of the cytoplasmic space, oxidative stress, and sperm function.

A method has been developed for quantifying the residual cytoplasm present in the midpiece of human spermatozoa, based upon the imaging of NADH oxidoreductase activity. This procedure used NADH and nitroblue tetrazolium as electron donor and acceptor, respectively, and resulted in the discrete staining of the entire midpiece area, including the residual cytoplasm. Image analysis techniques were then used to generate binary images of the midpiece, from which objective measurements of this cellular domain could be undertaken. Such data were found to be highly correlated with biochemical markers of the cytoplasmic space, such as creatine kinase (CK) and glucose-6-phosphate dehydrogenase (G-6-PDH), in sperm populations depleted of detectable leukocyte contamination. Morphometric analysis of the sperm midpiece was also found to reflect semen quality in that it predicted the proportion of the ejaculate that would be recovered from the high-density region of Percoll gradients and was negatively correlated with the movement and morphology of the spermatozoa in semen. Variation in the retention of excess residual cytoplasm was also associated with differences in the functional competence of washed sperm preparations, both within and between ejaculates. Thus, within-ejaculate comparisons of high- and low-density sperm subpopulations revealed a relative disruption of sperm function in the low-density fraction. This disruption was associated with the presence of excess residual cytoplasm in the midpiece, high concentrations of cytoplasmic enzymes, and the enhanced-generation reactive oxygen species (ROS). Functional differences between individual high-density Percoll preparations were also negatively correlated with the area of the midpiece and the corresponding capacity of the spermatozoa to generate ROS. These findings suggest that one of the factors involved in the etiology of defective sperm function is the incomplete extrusion of germ cell cytoplasm during spermiogenesis as a consequence of which the spermatozoa experience a loss of function associated with the induction of oxidative stress.

Biomarkers↗
PubMed1994

Improved Cytoplasmic pH Regulation, Increased Lactate Efflux, and Reduced Cytoplasmic Lactate Levels Are Biochemical Traits Expressed in Root Tips of Whole Maize Seedlings Acclimated to a Low-Oxygen Environment.

We tested the hypothesis (J.-H. Xia and P.H. Saglio [1992] Plant Physiol 100: 40-46) that the enhanced ability of maize (Zea mays) root tips to survive anoxia, elicited by a 4-h exposure to 3% O2 ("acclimation"), is due to less cytoplasmic acidosis early in anoxia. Cytoplasmic pH and fermentation reactions were monitored in excised and intact (attached) maize root tips by simultaneous in vivo 13C- and 31P-NMR spectroscopy. We demonstrate that both excised and intact acclimated root tips have significantly higher cytoplasmic pH values under anoxia. This reduction in cytoplasmic acidosis is greater in intact root tips. Remarkably, cytoplasmic pH does not change when root tips are transferred from 3% O2 to anoxia. The earlier observation of considerable lactate efflux and lowered intracellular lactate in excised, acclimated root tips (ibid.) was extended to intact seedlings. The predominant fermentation end product retained in the cells of acclimated root tips is alanine. We discuss the relationship between cytoplasmic pH and levels of intracellular lactate and alanine in sugar-replete roots, and the role of cytoplasmic pH in determining survival under anoxia.

Journal Article↗
PubMed1997

Cytoplasmic antineutrophil cytoplasmic antibody-positive vasculitis associated with ulcerative colitis.

The case of a man with poorly controlled ulcerative colitis, who developed a cytoplasmic antineutrophil cytoplasmic antibody-positive systemic vasculitis, causing small bowel infarction is reported. Antineutrophil cytoplasmic antibodies occur in 50-70% of patients with ulcerative colitis, but are usually of the perinuclear or atypical pattern; the cytoplasmic pattern seen in this case is indicative of systemic vasculitis. A variety of vasculitic diseases have been reported as occurring rarely with ulcerative colitis, but this report is the first description of a cytoplasmic antineutrophil cytoplasmic antibody-positive vasculitis with this association.

Adult↗
PubMed1992

Cis-allosteric effects of cytoplasmic Na+/K+ discrimination at varying pH. Low-affinity multisite inhibition of cytoplasmic K+ in reconstituted Na+/K(+)-ATPase engaged in uncoupled Na(+)-efflux.

In liposomes with reconstituted shark Na+/K(+)-ATPase the effect of cytoplasmic K+ was investigated in the absence of extracellular alkali ions. During such conditions the Na+/K(+)-ATPase is engaged in the so called uncoupled Na+ efflux mode in which cytoplasmic Na+ activates and binds to the enzyme and becomes translocated without countertransport of K+ as in the physiological Na+/K+ exchange mode. In this uncoupled flux mode only low-affinity inhibition by K+cyt is found to be present. The inhibition pattern is consistent with a model in which cytoplasmic K+ exhibit mixed inhibition of Na+ activation, probably by binding at the three cytoplasmic loading sites on E1ATP (E1A). With determined intrinsic binding constants for cytoplasmic Na+ to this form of KS1, KS2, KS3 = 40 mM, 2 mM, 2 mM the inhibition pattern can be simulated assuming three K+cyt sites with equal affinity for Ki = 40 mM, similar to KS1 for the first Na+cyt site. The discrimination between cytoplasmic Na+ and K+ is therefore enhanced by allosteric interaction initiated from the cis-side due to binding of the first Na+, as opposed to K+, which induces the positive cooperatively in the successive Na+ bindings. pH is found to influence the pattern of K+cyt inhibition: A lowering of the pH potentiates the K+cyt inhibition, whereas at increased pH the inhibition is decreased and transformed into a pure competitive competition.

Adenosine Triphosphate↗