ULTRASTRUKTURELLE VERÄNDERUNGEN DER ZELLMEMBRAN, BASALMEMBRAN UND KAPILLARE BEI VERSCHIEDENEN FUNKTIONSZUSTÄNDEN DER MENSCHLICHEN SCHILDDRÜSE

1972 ◽  
Vol 69 (3) ◽  
pp. 459-472 ◽  
Author(s):  
Peter Matthaes
Keyword(s):  
Membrane Potential ◽  
Basal Membrane ◽  
Human Thyroid ◽  
List Type ◽  
Cell Border ◽  
Morphological Criteria ◽  
Lateral Cell ◽  
Tsh Stimulation ◽  
State Of Activity ◽  
Metabolic Exchange

ABSTRACT Apical and basal membranes of activated cells show definite increase in membrane potential. Microvilli are frequently encountered, pseudopodia representing macropinocytosis infrequently. The lateral cell border shows definite morphological criteria of intercellular metabolic exchange. Small ducts lined by microvilli are described and discussed as to their relation to lymphatics. The formation and desintegration of the basal membrane is determined by hormonal (TSH) stimulation and the state of activity of the cell. Intraepithelial capillaries occurring in the human thyroid are described. Polar differentiation analogous to other organs can be demonstrated here as well.

scholarly journals Can citizen science analysis of camera trap data be used to study reproduction? Lessons from Snapshot Serengeti program

2020 ◽  
Author(s):  
Thel Lucie ◽  
Chamaillé-Jammes Simon ◽  
Keurinck Léa ◽  
Catala Maxime ◽  
Packer Craig ◽  
...  
Keyword(s):  
Citizen Science ◽  
Camera Trap ◽  
Camera Traps ◽  
Life History Trait ◽  
List Type ◽  
Breeding Phenology ◽  
Science Data ◽  
Morphological Criteria ◽  
Wide Range ◽  
Trained Observers

AbstractEcologists increasingly rely on camera trap data to estimate a wide range of biological parameters such as occupancy, population abundance or activity patterns. Because of the huge amount of data collected, the assistance of non-scientists is often sought after, but an assessment of the data quality is a prerequisite to their use.We tested whether citizen science data from one of the largest citizen science projects - Snapshot Serengeti - could be used to study breeding phenology, an important life-history trait. In particular, we tested whether the presence of juveniles (less than one or 12 months old) of three ungulate species in the Serengeti: topi Damaliscus jimela, kongoni Alcelaphus buselaphus and Grant’s gazelle Nanger granti could be reliably detected by the “naive” volunteers vs. trained observers. We expected a positive correlation between the proportion of volunteers identifying juveniles and their effective presence within photographs, assessed by the trained observers.We first checked the agreement between the trained observers for age classes and species and found a good agreement between them (Fleiss’ κ > 0.61 for juveniles of less than one and 12 month(s) old), suggesting that morphological criteria can be used successfully to determine age. The relationship between the proportion of volunteers detecting juveniles less than a month old and their actual presence plateaued at 0.45 for Grant’s gazelle and reached 0.70 for topi and 0.56 for kongoni. The same relationships were however much stronger for juveniles younger than 12 months, to the point that their presence was perfectly detected by volunteers for topi and kongoni.Volunteers’ classification allows a rough, moderately accurate, but quick, sorting of photograph sequences with/without juveniles. Obtaining accurate data however appears more difficult. We discuss the limitations of using citizen science camera traps data to study breeding phenology, and the options to improve the detection of juveniles, such as the addition of aging criteria on the online citizen science platforms, or the use of machine learning.

Fine structure of the kidneys of osmotically stressed Mytilus, Mercenari, and Anodonta

1986 ◽  
Vol 64 (12) ◽  
pp. 2779-2787 ◽  
Author(s):  
Hamidur R. Khan ◽  
Mary Lou Ashton ◽  
A. S. M. Saleuddin
Keyword(s):  
Basal Membrane ◽  
Ultrastructural Changes ◽  
Freshwater Bivalve ◽  
Septate Junctions ◽  
Intramembrane Particle ◽  
Marine Bivalves ◽  
Fluorescent Stain ◽  
Cytoskeletal Elements ◽  
Lateral Cell ◽  
Membrane Infoldings

Osmotically induced ultrastructural changes in the kidneys of the freshwater bivalve Anodonta and the marine bivalves Mytilus and Mercenaria were studied. Osmotic stresses were given to Anodonta by keeping them in distilled water or in 6% seawater, and to Mytilus and Mercenaria by keeping them in 50% seawater for various periods. In all of these bivalves, the convoluted, single cell layered kidney epithelia displayed wide lateral intercellular spaces as well as extracellular spaces in the basal membrane infoldings during hyposmotic stress. These spaces were greatly reduced when the animals were kept in isosmotic media (i.e., isosmotic to their respective hemolymphs). The kidney cells contained abundant cytoskeletal elements and microfilaments were often observed in bundles in the basal membrane infoldings. Actin was observed in the basal membrane infoldings using the specific fluorescent stain nitrobenzoxadiazole-phallacidin. The cell contacts of the kidney epthelia were studied in platinum replicas of freeze-fractured tissues. The lateral cell membrane and basal membrane infoldings contained many gap junctions. Many rows of dense intramembrane particles of septate junctions were observed in the kidneys of animals from isosmotic media. The septate junctions in the kidneys of aminals from hyposmotic media contained either fewer intramembrane particle rows or many sinuous intramembrane particle rows. The site of prourine formation in mollusks are discussed.

Effects of potassium channel modulators on myotropic responses of aortic rings of pregnant rats

2000 ◽  
Vol 278 (2) ◽  
pp. H567-H576 ◽  
Author(s):  
C. Cadorette ◽  
B. Sicotte ◽  
M. Brochu ◽  
J. St-Louis
Keyword(s):  
Membrane Potential ◽  
Potassium Channels ◽  
Basal Membrane ◽  
Maximal Response ◽  
Dependent Manner ◽  
Response Curves ◽  
Concentration Dependent Manner ◽  
Pregnant Rats ◽  
Potassium Channel Modulators ◽  
High Conductance

The contribution of potassium channels [ATP-sensitive potassium (KATP) and high-conductance calcium-activated potassium (BKCa) channels] in the resistance of aortic rings of term pregnant rats to phenylephrine (Phe), arginine vasopressin (AVP), and KCl was investigated. Concentration-response curves to tetraethylammonium (TEA), a nonselective K+ channel inhibitor, were obtained in the absence or presence of KCl. TEA induced by itself concentration-dependent responses only in aortic rings of nonpregnant rats. These responses to TEA could be modulated in both groups of rings by preincubation with different concentrations of KCl. Concentration-response curves to Phe, AVP, and KCl were obtained in the absence or presence of cromakalim or NS-1619 (KATP and BKCa openers, respectively) and glibenclamide or iberiotoxin (KATPand BKCa inhibitors, respectively). Cromakalim significantly inhibited the responses to the three agonists in a concentration-dependent manner in both groups of rats. Alternatively, in the pregnant group of rats, glibenclamide increased the sensitivity to all three agonists. NS-1619 also inhibited the response to all agonists. With AVP and KCl, its effect was greater in aortic rings of pregnant than nonpregnant rats. Finally, iberiotoxin increased the sensitivity to all three agents. This effect was more important in aortic rings of nonpregnant rats and was accompanied by an increase of the maximal response to Phe and AVP. These results suggest that potassium channels are implicated in the control of basal membrane potential and in the blunted responses to these agents during pregnancy.

Transepithelial and intracellular potentials in isolated Malpighian tubules of tenebrionid beetle

1987 ◽  
Vol 252 (4) ◽  
pp. F645-F653 ◽  
Author(s):  
S. W. Nicolson ◽  
L. C. Isaacson
Keyword(s):  
Membrane Potential ◽  
Basal Membrane ◽  
Fluid Secretion ◽  
Malpighian Tubules ◽  
Bathing Medium ◽  
Intracellular Potentials ◽  
Tenebrionid Beetle ◽  
Fold Reduction ◽  
K Concentration ◽  
Opposing Effects

Malpighian tubules of Onymacris plana (Coleoptera: Tenebrionidae) have been isolated for measurement of transepithelial and intracellular potentials, before and during stimulation of fluid secretion. In a bathing medium resembling the hemolymph composition of the insect, the transepithelial potential (VT) was approximately 13 mV, lumen positive. VT was subject to drift and frequently showed super-imposed regular oscillations, which were apparently action potentials associated with contractions of muscle fibers running along the tubules. Although tubules of Onymacris are approximately 8 cm long, the basal membrane potential (Vb) did not vary with distance along the tubule, averaging -31 mV. Addition of adenosine 3',5'-cyclic monophosphate (cAMP) or diuretic hormone (DH) homogenate to the bathing medium had no effect on Vb, but opposing effects on VT: cAMP caused it to increase to 60 mV, whereas DH homogenate caused a rapid drop in VT to almost zero. Ion substitutions in the bathing medium showed that under control conditions beetle tubules possessed appreciable basal permeability to both K and Cl ions, with a 10-fold reduction in bath K concentration hyperpolarizing Vb by 54 mV. The basal K and Cl channels were partially blocked by barium and thiocyanate ions, respectively. Stimulation with cAMP increased the apical membrane potential (Va) and significantly reduced the Cl permeability of the basal membrane, whereas its Na permeability remained negligible.

Basolateral impalement of intestinal villus cells: electrophysiology of Cl- transport

1989 ◽  
Vol 256 (5) ◽  
pp. C1022-C1032 ◽  
Author(s):  
J. F. White ◽  
D. Ellingsen
Keyword(s):  
Membrane Potential ◽  
Cell Layer ◽  
Basolateral Membrane ◽  
Basal Membrane ◽  
Direct Access ◽  
Intestinal Villus ◽  
Cl Transport ◽  
Conductive Pathway ◽  
Flat Sheet ◽  
Tip Cells

A method of dissecting the serosal muscle layers is described that transforms the villus of isolated Amphiuma small intestine into a flat sheet one cell layer thick, allowing rapid equilibration of the serosal medium with the basolateral membrane of the villus tip cells and direct access of the basal membrane to microelectrodes. The "villus sheet" preparation was used to examine the luminal and basolateral mechanisms of Cl- transport. The serosal membrane potential (Vs), measured with conventional microelectrodes, averaged -79.7 mV in tissues bathed in Cl- -free medium; the mucosal membrane potential (Vm) averaged -80.9 mV. Fractional resistance measured directly was 0.82 and 0.14 for the mucosal and serosal membranes, respectively. Elevation of bath [K] reduced Vm and Vs by 30.3 and 44.5 mV, respectively. Cl- (20 mM) added to the luminal medium reduced Vm by 23.9 mV and stimulated Cl- transport; luminal addition of furosemide then increased Vm by 5.6 mV and reduced Cl- transport. Addition of Cl- (20 mM) to the Cl- -free serosal fluid increased Vs 2.0 +/- 1.9 mV. On reducing the serosal [Cl] 10-fold Vs decreased 2.0 +/- 2.2 mV. These and other results indicate that basolateral Cl- exit is not over a conductive pathway. The villus sheet affords new opportunities for studying enterocyte function in the intact mucosa.

scholarly journals Protein Kinase Cδ Targets Mitochondria, Alters Mitochondrial Membrane Potential, and Induces Apoptosis in Normal and Neoplastic Keratinocytes When Overexpressed by an Adenoviral Vector

1999 ◽  
Vol 19 (12) ◽  
pp. 8547-8558 ◽  
Author(s):  
Luowei Li ◽  
Patricia S. Lorenzo ◽  
Krisztina Bogi ◽  
Peter M. Blumberg ◽  
Stuart H. Yuspa
Keyword(s):  
Cell Death ◽  
Membrane Potential ◽  
Protein Kinase ◽  
Mitochondrial Membrane Potential ◽  
Mitochondrial Membrane ◽  
Fluorescent Protein ◽  
Protein Fusion ◽  
Cell Death Pathway ◽  
Morphological Criteria ◽  
Protein Kinase Cδ

ABSTRACT Inactivation of protein kinase Cδ (PKCδ) is associated with resistance to terminal cell death in epidermal tumor cells, suggesting that activation of PKCδ in normal epidermis may be a component of a cell death pathway. To test this hypothesis, we constructed an adenovirus vector carrying an epitope-tagged PKCδ under a cytomegalovirus promoter to overexpress PKCδ in normal and neoplastic keratinocytes. While PKCδ overexpression was detected by immunoblotting in keratinocytes, the expression level of other PKC isozymes, including PKCα, PKCɛ, PKCζ, and PKCη, did not change. Calcium-independent PKC-specific kinase activity increased after infection of keratinocytes with the PKCδ adenovirus. Activation of PKCδ by 12-O-tetradecanoylphorbol-13-acetate (TPA) at a nanomolar concentration was lethal to normal and neoplastic mouse and human keratinocytes overexpressing PKCδ. Lethality was inhibited by PKC selective inhibitors, GF109203X and Ro-32-0432. TPA-induced cell death was apoptotic as evidenced by morphological criteria, TUNEL (terminal deoxynucleotidyltransferase-mediated dUTP-biotin nick end labeling) assay, DNA fragmentation, and increased caspase activity. Subcellular fractionation indicated that PKCδ translocated to a mitochondrial enriched fraction after TPA activation, and this finding was confirmed by confocal microscopy of cells expressing a transfected PKCδ-green fluorescent protein fusion protein. Furthermore, activation of PKCδ in keratinocytes altered mitochondrial membrane potential, as indicated by rhodamine-123 fluorescence. Mitochondrial inhibitors, rotenone and antimycin A, reduced TPA-induced cell death in PKCδ-overexpressing keratinocytes. These results indicate that PKCδ can initiate a death pathway in keratinocytes that involves direct interaction with mitochondria and alterations of mitochondrial function.

Abstract 1232: Regulation of Mitochondria membrane Potential by Shear Stress: Implication of NO Signaling

Circulation ◽  
2007 ◽  
Vol 116 (suppl_16) ◽  
Author(s):  
Mahsa Rouhanizadeh ◽  
Ryan Hamilton ◽  
Enrique Cadenas ◽  
Tzung Hsiai
Keyword(s):  
Nitric Oxide ◽  
Shear Stress ◽  
Membrane Potential ◽  
Manganese Superoxide Dismutase ◽  
Fluorescent Dyes ◽  
Energy State ◽  
No Production ◽  
List Type ◽  
No Donor ◽  
Mitochondria Membrane Potential

Introduction : Mitochondria are the most important source of intracellular reactive oxygen species (ROS) in vascular endothelial cells (EC). Mitochondrial membrane potential (ΔΨm) is an indicator of mitochondrial energy state and mtROS production. Shear stress is known to induce eNOS and produce nitric oxide (NO). Hypothesis: We assessed whether NO is implicated in shear stress-induced ΔΨm and mtROS generation. Methods : Confluent HAEC were subjected to three conditions: static control (τ ave = 0 dyn.cm −2 at ∂τ/∂t = 0); pulsatile shear stress (PSS) at a mean shear stress (τ ave ) of 23 dyn.cm −2 with a temporal variation (∂τ/∂t) at 71 dyn.cm −2 .s −1 ; and oscillatory shear stress (OSS) at τ ave = 0.02 with ∂τ/∂t at ±3 dyn.cm − 2.s −1 . Tetramethyl rhodamine methyl ester (TMRM) and Mitosox red fluorescent dyes were used to assess mitochondrial ΔΨm and O 2 ·− production respectively. Intracellular H 2 O 2 production was assessed by carboxy-H 2 DCFDA. HAEC were treated with DETA-NO (NO donor) and L-NAME (eNOS inhibitor) to assess how shear stress-induced NO production regulates ΔΨm. Results: Delta;Ψm was increased by 12±5.3 mV in response to OSS, and by 33.5±8.9 mV in response to PSS (n=3, P <0.05) relative to static control. DETA-NO at 0.21mM and 0.94mM was used to simulate PSS-induced NO production during 1 hour and 4 hours of flow and it increased Delta;Ψm by 9.6±4.9 mV and 18.9 ±3.2 mV, respectively (n=3, P<0.05). L-NAME reduced Delta;Ψm (n=3, P<0.05) suggesting that NO is involved in Delta;Ψm regulation. PSS-induced Delta;Ψm was accompanied by a 1.4 fold increase in mtROS production (n=3, P<0.05) and a concomitant 10 fold upregulation in mitochondrial manganese superoxide dismutase (MnSOD) mRNA expression (n=6, P<0.05). Conclusion: Nitric oxide modulates Delta;Ψm and mtROS production. PSS, which upregulates eNOS, is more potent than OSS at increasing Delta;Ψm and mtROS, implicating NO as a signaling molecule in mitochondrial and endothelial function.

scholarly journals Changes in apical [K+] produce delayed basal membrane responses of the retinal pigment epithelium in the gecko.

1984 ◽  
Vol 83 (2) ◽  
pp. 193-211 ◽  
Author(s):  
E R Griff ◽  
R H Steinberg
Keyword(s):  
Membrane Potential ◽  
Retinal Pigment Epithelium ◽  
Apical Membrane ◽  
Pigment Epithelium ◽  
Retinal Pigment ◽  
Basal Membrane ◽  
Subretinal Space ◽  
Bathing Solution ◽  
Subsequent Decrease ◽  
Opposite Sequence

We describe here a new retinal pigment epithelium (RPE) response, a delayed hyperpolarization of the RPE basal membrane, which is initiated by the light-evoked decrease of [K+]o in the subretinal space. This occurs in addition to an apical hyperpolarization previously described in cat (Steinberg et al., 1970; Schmidt and Steinberg, 1971) and in bullfrog (Oakley et al., 1977; Oakley, 1977). Intracellular and extracellular potentials and measurements of subretinal [K+]o were recorded from an in vitro preparation of neural retina-RPE-choroid from the lizard Gekko gekko in response to light. Extracellularly, the potential across the RPE, the transepithelial potential (TEP), first increased and then decreased during illumination. Whereas the light-evoked decrease in [K+]o predicted the increase in TEP, the subsequent decrease in TEP was greater than predicted by the reaccumulation of [K+]o. Intracellular RPE recordings showed that a delayed hyperpolarization generated at the RPE basal membrane produced the extra TEP decrease. At light offset, the opposite sequence of membrane potential changes occurred. RPE responses to changes in [K+]o were studied directly in the isolated gecko RPE-choroid. Decreasing [K+]o in the apical bathing solution produced first a hyperpolarization of the apical membrane, followed by a delayed hyperpolarization of the basal membrane, a sequence of membrane potential changes identical to those evoked by light. Increasing [K+]o produced the opposite sequence of membrane potential changes. In both preparations, the delayed basal membrane potentials were accompanied by changes in basal membrane conductance. The mechanism by which a change in extracellular [K+] outside the apical membrane leads to a polarization of the basal membrane remains to be determined.

scholarly journals Induction of follicle formation in long-term cultured normal human thyroid cells treated with thyrotropin stimulates iodide uptake but not sodium/iodide symporter messenger RNA and protein expression

2000 ◽  
Vol 167 (1) ◽  
pp. 125-135 ◽  
Author(s):  
T Kogai ◽  
F Curcio ◽  
S Hyman ◽  
EM Cornford ◽  
GA Brent ◽  
...  
Keyword(s):  
Messenger Rna ◽  
Sodium Iodide ◽  
Human Thyroid ◽  
Sodium Iodide Symporter ◽  
Iodide Uptake ◽  
Thyroid Cells ◽  
Protein Levels ◽  
Normal Human ◽  
Tsh Stimulation ◽  
Stimulation Of

Iodide uptake by the sodium/iodide symporter (NIS) in thyrocytes is essential for thyroid hormone production. Reduced NIS activity has been reported in thyroid diseases, including thyroid cancer and congenital hypothyroidism. The study of iodide uptake in thyrocytes has been limited by the availability of appropriate in vitro models. A new culture technique was recently developed that allows normal human thyroid primary culture cells to grow as monolayer cells and express differentiated functions for more than 3 months. We used this technique to study the effect of follicle formation and TSH on iodide uptake in these cells. Iodide uptake by the cells grown in monolayer was very low. Follicle formation was induced from monolayer cells, and electron micrographs demonstrated cell polarity in the follicles. No significant increase in iodide uptake was observed after TSH treatment of cells in monolayer or when follicle formation was induced without TSH. TSH stimulation of follicles, however, significantly increased iodide uptake ( approximately 4. 4-fold; P<0.001). Compared with iodide uptake in monolayers, the combination of follicle formation and TSH treatment stimulated iodide uptake synergistically to 12.0-fold (P<0.001). NIS messenger RNA (mRNA) and protein levels were almost the same in both monolayer cells and follicles. TSH treatment of monolayers and follicles produced significant (P<0.05) stimulation of mRNA ( approximately 4. 8- and approximately 4.3-fold respectively) and protein ( approximately 6.8- and 4.9-fold respectively). TSH stimulated NIS protein levels in both monolayer and follicles, however, stimulation of functional iodide uptake was only seen with TSH stimulation of follicles. The function of NIS may involve post-transcriptional events, such as intracellular sorting, membrane localization of NIS or another NIS regulatory factor. Polarized functions, such as iodide efflux into follicular lumina, may also contribute to the increased iodide concentration after follicle formation.

scholarly journals Human placental syncytiotrophoblast expresses two pharmacologically distinguishable types of Na+-H+ exchangers, NHE-1 in the maternal-facing (brush border) membrane and NHE-2 in the fetal-facing (basal) membrane

1992 ◽  
Vol 284 (1) ◽  
pp. 33-38 ◽  
Author(s):  
P Kulanthaivel ◽  
T C Furesz ◽  
A J Moe ◽  
C H Smith ◽  
V B Mahesh ◽  
...  
Keyword(s):  
Membrane Potential ◽  
Brush Border ◽  
Brush Border Membrane ◽  
Membrane Vesicles ◽  
Basal Membrane ◽  
Na Channel ◽  
Normal Term ◽  
Na Uptake ◽  
Pharmacological Profiles

We investigated whether highly purified preparations of basal (fetal-facing) membrane isolated from normal term human placentas possess Na(+)-H+ exchanger activity. Uptake of Na+ into basal membrane vesicles was stimulated many-fold by an outwardly directed H+ gradient. This H(+)-gradient-dependent uptake was inhibitable by amiloride and its analogues. Na+ uptake in these vesicles did not occur via a Na+ channel, as it was not influenced by changes in membrane potential and, in addition, was inhibited by benzamil only at high micromolar concentrations. The results indicate that the human placental basal membrane possesses Na(+)-H+ exchanger activity. We then studied whether this exchanger is similar to or distinct from the Na(+)-H+ exchanger described in brush border (maternal-facing) membrane preparations. For this purpose, we compared the pharmacological characteristics of the basal membrane Na(+)-H+ exchanger with those of the brush border membrane Na(+)-H+ exchanger. The basal membrane exchanger was about 20-fold less sensitive to inhibition by amiloride and about 70-fold less sensitive to inhibition by dimethylamiloride than was the brush border membrane exchanger. The exchanger activity in both membrane preparations was inhibitable by clonidine and cimetidine, but the inhibition patterns with these compounds were markedly different between basal and brush border membrane preparations. These data demonstrate that the basal membrane Na(+)-H+ exchanger is distinct from the brush border membrane Na(+)-H+ exchanger. The pharmacological profiles of these exchangers indicate that the human placental brush border membrane possesses the housekeeping or non-epithelial type Na(+)-H+ exchanger (NHE-1), whereas the basal membrane possesses the epithelial or apical type Na(+)-H+ exchanger (NHE-2).

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