Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:P50583 (asymmetrical)
 12,197 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The amidated tetrapeptide Ala-Pro-Gly-Trp-NH2 (APGWamide) plays a key role in the control of male copulation behavior in the basommatophoran pulmonate freshwater snail Lymnaea stagnalis. The morphological basis for a conserved role of APGWamide in the control of male reproduction in gastropod molluscs is presented. The prosobranch Littorina littorea, the opisthobranch Aplysia californica, the basommatophoran pulmonate Bulinus truncatus, and the stylommatophoran pulmonates Arion ater and Limax maximus have been examined for the presence of APGWamide producing neurons using immunocytochemistry and in situ hybridization. In all species investigated a cluster of APGWamide expressing neurons is present in the anteromedial region of the cerebral ganglia. The asymmetrical distribution which exists in Lymnaea and which coincides with the innervation of the asymmetrically located penial complex is also found in the opisthobranch Aplysia, as well as in the stylommatophoran pulmonate slugs Arion and Limax, in which APGWamide immunoreactive neurons are only found in the mesocerebrum of the right cerebral ganglion. APGWamide immunoreactive varicose fibers innervate muscles of the male accessory sex organs in Bulinus and Aplysia, confirming the hypothesis that APGWamide may be a biochemically and functionally conserved factor in the regulation of gastropod mollusc reproduction.
Gen Comp Endocrinol 1998 Feb
PMID:Localization of the neuropeptide APGWamide in gastropod molluscs by in situ hybridization and immunocytochemistry. 947 61

The cystic fibrosis transmembrane conductance regulator (CFTR) forms a tightly regulated channel that mediates the passive diffusion of Cl- ions. Here we show, using macroscopic current recording from excised membrane patches, that CFTR also shows significant, but highly asymmetrical, permeability to a broad range of large organic anions. Thus, all large organic anions tested were permeant when present in the intracellular solution under biionic conditions (PX/PCl = 0.048-0.25), whereas most were not measurably permeant when present in the extracellular solution. This asymmetry was not observed for smaller anions. ATPase inhibitors that "lock" CFTR channels in the open state (pyrophosphate, 5'-adenylylimidodiphosphate) disrupted the asymmetry of large anion permeation by allowing their influx from the extracellular solution, which suggests that ATP hydrolysis is required to maintain asymmetric permeability. The ability of CFTR to allow efflux of large organic anions represents a novel function of CFTR. Loss of this function may contribute to the pleiotropic symptoms seen in cystic fibrosis.
J Gen Physiol 1998 Apr
PMID:Adenosine triphosphate-dependent asymmetry of anion permeation in the cystic fibrosis transmembrane conductance regulator chloride channel. 952 41

The summer flounder (Paralichthys dentatus) undergoes a true metamorphosis during which the bilaterally symmetrical larva transforms into an asymmetrical juvenile. This study addresses the influence of manipulating thyroid status on larval development and growth. Development was assessed by categorizing larvae in stages based on the position of the translocating eye and growth was assessed as a change in total length. Larvae were raised in seawater or in seawater containing thyroxine-sodium salt (100 ppb, T4) or thiourea (30 ppm, TU). Ambient T4 raised whole-animal T4 concentration almost threefold, whereas treatment with TU reduced whole-animal T4 concentration by 95%. The whole-animal T4 concentrations of untreated larvae increased during metamorphic climax (MC) and were related to developmental stage rather than age. Altering thyroid status of larvae in different stages had different consequences. T4 treatment of late premetamorphic (late pre-M) larvae accelerated their rate of development to prometamorphosis (pro-M), early MC, and mid MC, whereas TU treatment at this stage caused developmental stasis in early MC. T4 treatment of pro-M larvae accelerated development to early MC only and, unlike the response of late pre-M larvae, some of the pro-M larvae treated with TU slowly developed to late MC. TU treatment could inhibit completion of metamorphosis in early MC and mid MC, but not in late MC. Thyroid status of larvae had no effect on growth. However, starting at an age when most untreated and T4-treated larvae were in late MC, they began to grow longer than TU-treated larvae in developmental stasis at early MC and mid MC. Thus, T4 is necessary and sufficient for metamorphosis in summer flounder and, at this single dose, has a more pronounced effect on development at earlier stages.
Gen Comp Endocrinol 1998 Aug
PMID:Metamorphosis in the summer flounder (Paralichthys dentatus): stage-specific developmental response to altered thyroid status. 967 87

Foamy viruses (FVs) make use of a replication strategy which is unique among retroviruses and shows analogies to hepadnaviruses. The presence of an integrase (IN) and obligate provirus integration distinguish retroviruses from hepadnaviruses. To clarify whether a functional IN is required for FV replication, a mutant in the highly conserved DD35E motif of the active centre was analysed. This mutant was found to be able to express Gag and Pol protein precursors and cleavage products and to generate and deliver cDNA. However, this mutant was replication-deficient. The junctions of individual foamy proviruses with cellular DNA were sequenced. The findings suggest that FV integration is asymmetrical, because the proviruses started with what is believed to be the U3 end of the free linear DNA to generate the conventional TG dinucleotide, while apparently two nucleotides from the U5 end were cleaved to create the complementary CA dinucleotide. Alignment of known FV genome sequences indicated that this mechanism of integration is not restricted to the two FV isolates from which integrates were studied, but appears to be a common feature of this retrovirus subfamily. In conclusion, with respect to the necessity of a functionally active IN for virus replication FVs behave like other retroviruses; their mechanism of integration, however, is probably unique.
J Gen Virol 1999 Jun
PMID:An active foamy virus integrase is required for virus replication. 1037 62

The effects of 3,5',3'-triiodo-L-thyronine (T3; 10 or 100 ng ml(-1)), alone or combined with cortisol (500 ng ml(-1)), on the physiological properties of cultured pavement cell epithelia from freshwater rainbow trout gills were assessed. T3 had dose-dependent effects on electrophysiological, biochemical, and ion transporting properties of cultured epithelia in both the absence and the presence of cortisol. These included reduced transepithelial resistance (TER), increased net Na(+) and Cl(-) movement (basolateral to apical) under asymmetrical culture conditions (freshwater apical/L15 media basolateral), and elevated Na(+)-K(+)-ATPase activity. However, paracellular permeability was elevated only in high-dose T3-treated preparations. In T3 + cortisol-treated epithelia, similar T3-induced alterations in TER, net Na(+) and Cl(-) movement, and paracellular permeability were observed, whereas the activity of Na(+)-K(+)-ATPase was further elevated. Under symmetrical culture conditions (L15 medium apical/L15 medium basolateral), T3 had no effect on transepithelial Na(+) and Cl(-) transport, which was passive. However, T3 + cortisol treatment resulted in active Na(+) extrusion (basolateral to apical). Under asymmetrical conditions, hormone treatment did not change the pattern of ion movement (active Na(+) extrusion, active Cl(-) uptake). These experiments demonstrate that cultured pavement cell epithelia from freshwater rainbow trout are T3-responsive and provide evidence for the direct action of T3 and the interaction of T3 and cortisol on the physiology of this preparation.
Gen Comp Endocrinol 2001 Sep
PMID:The physiological effects of 3,5',3'-triiodo-L-thyronine alone or combined with cortisol on cultured pavement cell epithelia from freshwater rainbow trout gills. 1158 29

Tetrodotoxin-resistant (TTX-R) Na(+) channels are 1,000-fold less sensitive to TTX than TTX-sensitive (TTX-S) Na(+) channels. On the other hand, TTX-R channels are much more susceptible to external Cd(2+) block than TTX-S channels. A cysteine (or serine) residue situated just next to the aspartate residue of the presumable selectivity filter "DEKA" ring of the TTX-R channel has been identified as the key ligand determining the binding affinity of both TTX and Cd(2+). In this study we demonstrate that the binding affinity of Cd(2+) to the TTX-R channels in neurons from dorsal root ganglia has little intrinsic voltage dependence, but is significantly influenced by the direction of Na(+) current flow. In the presence of inward Na(+) current, the apparent dissociation constant of Cd(2+) ( approximately 200 microM) is approximately 9 times smaller than that in the presence of outward Na(+) current. The Na(+) flow-dependent binding affinity change of Cd(2+) block is true no matter whether the direction of Na(+) current is secured by asymmetrical chemical gradient (e.g., 150 mM Na(+) vs. 150 mM Cs(+) on different sides of the membrane, 0 mV) or by asymmetrical electrical gradient (e.g., 150 mM Na(+) on both sides of the membrane, -20 mV vs. 20 mV). These findings suggest that Cd(2+) is a pore blocker of TTX-R channels with its binding site located in a multiion, single-file region near the external pore mouth. Quantitative analysis of the flow dependence with the flux-coupling equation reveals that at least two Na(+) ions coexist with the blocking Cd(2+) ion in this pore region in the presence of 150 mM ambient Na(+). Thus, the selectivity filter of the TTX-R Na(+) channels in dorsal root ganglion neurons might be located in or close to a multiion single-file pore segment connected externally to a wide vestibule, a molecular feature probably shared by other voltage-gated cationic channels, such as some Ca(2+) and K(+) channels.
J Gen Physiol 2002 Aug
PMID:Effect of Na(+) flow on Cd(2+) block of tetrodotoxin-resistant Na(+) channels. 1214 78

We analyzed the participation of sympathetic ovarian innervation in the prepubertal female guinea pig on regulation of compensatory ovarian hypertrophy (COH) and compensatory ovulation at puberty. The COH of the left ovary was significantly higher that of the right one (left ovary: 41.5+/-5.2 vs. 27.5+/-5.6%, p<0.05, Kruskal-Wallis test). The sympathetic denervation induced by guanethidine administration beginnings at birth or on day 10 resulted in a significant increase of the COH by each ovary (p<0.05, Kruskal-Wallis test). Only one of the six untreated control guinea pigs sacrificed at the follicular phase ovulate. All the hemiovariectomized animals with the left ovary in situ ovulated, while only two out of five with the right ovary in situ did (100 vs. 40%: p<0.001, Kruskal-Wallis test), unlike the denervated animals, which did not ovulate. The number of corpora lutea present in the ovaries was similar among all groups of animals. These results demonstrate differences in the follicular diameter in untreated female guinea pigs and add further support to the concept of asymmetrical response of the ovaries to denervation.
Gen Comp Endocrinol 2002 Jul
PMID:Effects of guanethidine administration on compensatory ovarian hypertrophy, compensatory ovulation and follicular development in the prepubertal female guinea pig. 1222 70

The physiological effects of ovine prolactin (oPRL) and recombinant rainbow trout prolactin (rbtPRL) on cultured gill epithelia derived from freshwater rainbow trout were assessed. Epithelia composed of either pavement cells only (single seeded inserts, SSI) or both pavement and mitochondria-rich cells (double seeded inserts, DSI) were cultured in media, supplemented with doses of oPRL ranging from 10 to 100 ng/ml. Under symmetrical culture conditions (L15 media apical/L15 media basolateral), oPRL had no effect on transepithelial resistance, paracellular permeability (assessed with PEG-4000), or Na(+) and Cl(-) transport across both preparations of cultured gill epithelia. Under asymmetrical conditions (freshwater apical/L15 media basolateral), SSI epithelia treated with oPRL (10 and 50 ng/ml), in comparison to comparably treated epithelia receiving no oPRL, exhibited a greater increase in the transepithelial resistance, particularly during the first 12h of freshwater exposure, no difference in paracellular permeability and Na(+)-K(+)-ATPase activity, and lowered net Na(+) flux rates (i.e., reduced basolateral to apical loss rates). These reflected reduced unidirectional efflux rates. The PRL effect appeared to be mainly a reduction in transcellular permeability. SSI epithelia treated with rbtPRL (10 ng/ml) exhibited similar patterns of response to those treated with oPRL. Na(+)-K(+)-ATPase activity increased in DSI epithelia treated with oPRL; however, oPRL did not stimulate ion uptake across either SSI or DSI epithelial preparations. The data demonstrated that, as the sole hormone supplement for cultured gill epithelia, PRL did not promote active ion uptake. However, the observed PRL-induced alterations in cultured gill epithelial physiology were consistent with the in vivo actions of PRL on the gills of freshwater teleost fish.
Gen Comp Endocrinol 2002 Aug
PMID:Prolactin effects on cultured pavement cell epithelia and pavement cell plus mitochondria-rich cell epithelia from freshwater rainbow trout gills. 1227 Jul 87

A study has been made of conditions that support monosynaptic reflex transmission from afferent fibers of one part of a synergic muscle mass to motoneurons of another part. Heteronymous response so called can be brought on by prior tetanization of the afferent pathway and by asphyxiation to a critical stage. The response is facilitated by cooling and may appear in the cold preparation without need for prior tetanization. By appropriate asymmetrical subdivision of a monosynaptic reflex system an afferent inflow can be obtained that is sufficiently powerful to secure heteronymous transmission without the need for prior tetanization or cooling. Each junction between a monosynaptic afferent fiber and a motoneuron possesses some degree of potentiality for transmitting. Transmitter potentiality of an afferent fiber at its several junctions with motoneurons varies widely. Reasons are advanced for supposing the variation to be graded rather than stepwise, and quantitative rather than qualitative.
J Gen Physiol 1955 Jan 20
PMID:Transmission in fractionated monosynaptic spinal reflex systems. 1322 75

Stable electrical potential differences can be measured by means of conventional glass microelectrodes across the cell membrane of renal tubule cells and across the epithelial wall of single tubules in the doubly perfused kidney of Necturus. These measurements have been carried out with amphibian Ringer's solution, and with solutions of altered ionic composition. The proximal tubule cell has been found to be electrically asymmetrical inasmuch as a smaller potential difference is maintained across the luminal cell membrane than across the peritubular cell boundary. The tubule lumen is always electrically negative with respect to the peritubular extracellular medium. Observations on the effectiveness of potassium ions in depolarizing single tubule cells indicate that the transmembrane potential is essentially an inverse function of the logarithm of the external potassium concentration. The behavior of the peritubular transmembrane potential resembles more closely an ideal potassium electrode than that of the luminal transmembrane potential. From these results, and the effects of various ionic substitutions on the electrical profile of the renal tubular epithelium, a thesis concerning the origin of the observed potential differences is presented. A sodium extrusion mechanism is considered to be located at the peritubular cell boundary, and reasons are given for the hypothesis that the electrical asymmetry across the proximal renal tubule cell could arise as a consequence of differences in the relative sodium and potassium permeability at the luminal and peritubular cell boundaries.
J Gen Physiol 1961 Mar
PMID:Measurements of electrical potential differences on single nephrons of the perfused Necturus kidney. 1370 46


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