Climate Change May Alter Both Establishment and High Abundance of Red Brome (Bromus rubens) and African Mustard (Brassica tournefortii) in the Semiarid Southwest United States

2015 ◽  
Vol 8 (3) ◽  
pp. 341-352 ◽  
Author(s):  
Caroline A. Curtis ◽  
Bethany A. Bradley
Keyword(s):  
United States ◽  
Invasive Plants ◽  
High Abundance ◽  
High Threshold ◽  
Climatic Suitability ◽  
Worst Case ◽  
Red Brome ◽  
Brassica Tournefortii ◽  
Bromus Rubens ◽  
Low Threshold

AbstractNonnative, invasive plants are becoming increasingly widespread and abundant throughout the southwestern United States, leading to altered fire regimes and negative effects on native plant communities. Models of potential invasion are pertinent tools for informing regional management. However, most modeling studies have relied on occurrence data, which predict the potential for nonnative establishment only and can overestimate potential risk. We compiled locations of presence and high abundance for two problematic, invasive plants across the southwestern United States: red brome (Bromus rubens L.) and African mustard (Brassica tournefortii Gouan). Using an ensemble of five climate projections and two types of distribution model (MaxEnt and Bioclim), we modeled current and future climatic suitability for establishment of both species. We also used point locations of abundant infestations to model current and future climatic suitability for abundance (i.e., impact niche) of both species. Because interpretations of future ensemble models depend on the threshold used to delineate climatically suitable from unsuitable areas, we applied a low threshold (1 model of 10) and a high threshold (6 or more models of 10). Using the more-conservative high threshold, suitability for Bromus rubens presence expands by 12%, but high abundance contracts by 42%, whereas suitability for Brassica tournefortii presence and high abundance contract by 34% and 56%, respectively. Based on the low threshold (worst-case scenario), suitability for Bromus rubens presence and high abundance are projected to expand by 65% and 64%, respectively, whereas suitability for Brassica tournefortii presence and high abundance expand by 29% and 28%, respectively. The difference between results obtained from the high and low thresholds is indicative of the variability in climate models for this region but can serve as indicators of best- and worst-case scenarios.

Legal Aspects of Psychopharmacology Practice

2018 ◽  
pp. 429-436
Author(s):  
S. Nassir Ghaemi
Keyword(s):  
United States ◽  
Clinical Practice ◽  
Legal System ◽  
The United States ◽  
Legal Aspects ◽  
High Threshold ◽  
Legal Risks ◽  
Treatment Plans ◽  
Refusal To Treat ◽  
Low Threshold

The United States is characterized by a very aggressive legal system, where many complaints and lawsuits occur. Psychiatrists are vulnerable to such reactions by patients, sometimes justified, often not justified. Paying attention to legal risks is an unavoidable and necessary part of clinical practice. Besides malpractice concerns, which occur infrequently and with a high threshold, clinicians should be aware of the much more common practice of complaints to state medical regulatory boards. Such complaints have a low threshold and involve a bias against clinicians. Besides adequate documentation and attention to transference, clinicians should ensure that patients engage in agreed-upon treatment plans. Refusal to treat and/or termination of treatment is an important mechanism that clinicians need to employ to counteract legal risks.

Chronic Estrogen Sensitizes a Subset of Mechanosensitive Afferents Innervating the Uterine Cervix

2005 ◽  
Vol 93 (4) ◽  
pp. 2167-2173 ◽  
Author(s):  
Baogang Liu ◽  
James C. Eisenach ◽  
Chuanyao Tong
Keyword(s):  
Spontaneous Activity ◽  
Uterine Cervix ◽  
Firing Frequency ◽  
High Threshold ◽  
Group 13 ◽  
Ovx Rats ◽  
Afferent Fibers ◽  
Low Threshold ◽  
Group 5 ◽  
Afferent Response

Estrogen increases reflex nocifensive responses to distension of the uterus and the urinary bladder, but estrogen's effects on afferent response to distension of the uterine cervix, the site of obstetric and some gynecologic pain, has not been studied. Here, single fiber recording of hypogastric nerve responses to uterine cervical distension were obtained from ovariectomized (OVX) rats and OVX rats treated with estrogen (ES). Spontaneous activity was greater in the ES group (13 of 24 units; 54%) than in the OVX group (6 of 27 units; 22%). ES differentially altered the response of low- and high-threshold units to distension. For high-threshold units, firing frequency was increased two- to fourfold with 60–100 gm distension in ES compared with OVX groups ( P < 0.05). In contrast, the response of low-threshold units to distension was not altered by ES. About one-half of units tested in each group responded to a temperature increase from 35 to 49°C. A greater proportion of thermosensitive units were also mechanosensitive in the ES group (7 of 8 afferents, 88%) than in the OVX group (5 of 11 afferents, 45%). Acute application of ES in OVX rats failed to evoke or increase distension-induced responses. These data show the polymodal nature of afferent fibers innervating the uterine cervix. Increased spontaneous activity with ES may play a part in remodeling of the cervical tissue, whereas selective sensitization of high-threshold units by ES might underlie increased pain responses to cervical distension. Failure of acute ES treatment to mimic this suggests a genomic effect.

scholarly journals Progression of Sugarberry (Celtis laevigata) Dieback and Mortality in the Southeastern United States

2021 ◽  
Author(s):  
Emilee M Poole ◽  
Michael D Ulyshen ◽  
Scott Horn ◽  
Patrick Anderson ◽  
Chip Bates ◽  
...  
Keyword(s):  
United States ◽  
North America ◽  
Invasive Plants ◽  
Southeastern United States ◽  
Public Spaces ◽  
Canopy Gaps ◽  
Leaf Fall ◽  
Affected Area ◽  
Celtis Laevigata ◽  
Branch Dieback

Abstract The southeastern United States has been experiencing unexplained sugarberry (Celtis laevigata) mortality for over a decade, representing one of the most severe and widespread Celtis mortality episodes ever reported from North America. Here we describe external symptoms, progression of mortality, and the known geographic extent of the problem. More than half of all trees monitored at one site within the affected area died over five years of observation. Although many trees died within a year of first exhibiting symptoms (e.g., small yellow leaves, branch dieback, premature leaf fall), many others continued living for years after becoming symptomatic. A preliminary insecticide trial found no improvements in survivorship among trees treated with insecticides, emamectin benzoate and imidacloprid, relative to control trees. Our findings suggest the problem will likely continue and become more widespread in the coming years. Study Implications Sugarberry mortality in urban and forested environments is an ongoing problem that has the potential to spread throughout the southeastern United States and perhaps more widely, depending on the susceptibility of other native Celtis species. Many trees die within a year of first showing external symptoms, whereas others can live for many years after appearing symptomatic. Declining trees in rights-of-way and public spaces are presenting costly hazards to cities, and canopy gaps in natural areas are likely to facilitate the establishment and spread of invasive plants. Studies aimed at determining the cause of this problem are urgently needed.

Electrophysiology of neurosecretory cells from the pituitary intermediate lobe

1988 ◽  
Vol 139 (1) ◽  
pp. 317-328
Author(s):  
R. N. McBurney ◽  
S. J. Kehl
Keyword(s):  
Cell Cultures ◽  
Calcium Ion ◽  
Action Potentials ◽  
Neurosecretory Cells ◽  
Secretory Process ◽  
High Threshold ◽  
Pars Intermedia ◽  
Low Threshold ◽  
Stimulus Secretion Coupling ◽  
Ca2 Channels

One of the goals in studying the electrical properties of neurosecretory cells is to relate their electrical activity to the process of secretion. A central question in these studies concerns the role of transmembrane calcium ion flux in the initiation of the secretory event. With regard to the secretory process in pituitary cells, several research groups have addressed this question in vitro using mixed primary anterior pituitary cell cultures or clonal cell lines derived from pituitary tumours. Other workers, including ourselves, have used homogeneous cell cultures derived from the pituitary intermediate lobes of rats to examine the characteristics of voltage-dependent conductances, the contribution of these conductances to action potentials and their role in stimulus-secretion coupling. Pars intermedia (PI) cells often fire spontaneous action potentials whose frequency can be modified by the injection of sustained currents through the recording electrode. In quiescent cells action potentials can also be evoked by the injection of depolarizing current stimuli. At around 20 degrees C these action potentials have a duration of about 5 ms. Although most of the inward current during action potentials is carried by sodium ions, a calcium ion component can be demonstrated under abnormal conditions. Voltage-clamp experiments have revealed that the membrane of these cells contains high-threshold, L-type, Ca2+ channels and low-threshold Ca2+ channels. Since hormone release from PI cells appears not to be dependent on action potential activity but does depend on external calcium ions, it is not clear what role these Ca2+ channels play in stimulus-secretion coupling in cells of the pituitary pars intermedia. One possibility is that the low-threshold Ca2+ channels are more important to the secretory process than the high-threshold channels.

Metabotropic glutamate receptor-mediated suppression of L-type calcium current in acutely isolated neocortical neurons

1992 ◽  
Vol 68 (3) ◽  
pp. 833-842 ◽  
Author(s):  
R. J. Sayer ◽  
P. C. Schwindt ◽  
W. E. Crill
Keyword(s):  
Glutamate Receptor ◽  
Pyramidal Neurons ◽  
Metabotropic Glutamate Receptor ◽  
High Threshold ◽  
External Application ◽  
Metabotropic Glutamate ◽  
Neocortical Neurons ◽  
Old Rats ◽  
Low Threshold ◽  
Ca2 Channels

1. The effects of metabotropic glutamate receptor (mGluR) stimulation on whole-cell Ca2+ currents were studied in pyramidal neurons isolated from the dorsal frontoparietal neocortex of rat. The selective mGluR agonist cis-(+/-)-1-aminocyclopentane-1,3-dicarboxylic acid [trans-ACPD (100 microM)] suppressed the peak high-threshold Ca2+ current by 21 +/- 1.7% (mean +/- SE) in 40 of 43 cells from 10- to 21-day-old rats. Consistent with previous findings for mGluR, glutamate, quisqualate, and ibotenate [but not alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA)] reduced the Ca2+ currents, and the responses were not blocked by the ionotropic glutamate receptor antagonists 6-cyano-7-nitro-quinoxaline-2,3-dione (CNQX) and DL-2-amino-5-phosphonovaleric acid (APV). EC50S for Ca2+ current suppression were 29 nM for quisqualate, 2.3 microM for glutamate, and 13 microM for trans-ACPD. 2. The low-threshold Ca2+ current was not modulated by trans-ACPD. The component of the high-threshold CA2+ current suppressed by mGluR was determined by pharmacology; the responses were not affected by omega-conotoxin GVIA but were occluded by the dihydropyridine Ca2+ antagonist nifedipine. Ca2+ tail currents prolonged by the dihydropyridine Ca2+ agonist (+)-SDZ 202-79] were suppressed by mGluR stimulation in parallel with the peak current. These findings strongly suggest that L-type Ca2+ channels are modulated by mGluR. 3. In neurons dialyzed with 100 microM guanosine 5'-(gamma-thio)triphosphate (GTP-gamma-S), Ca2+ current suppression was elicited by the first application of trans-ACPD (in 5 of 6 cells), but not by subsequent applications. Responses in neurons dialyzed with 2 mM guanosine 5'-(beta-thio)diphosphate (GDP-beta-S) were significantly smaller than controls. The results are consistent with mGluR acting via linkage to a G protein. 4. The responses to mGluR agonists were smaller when the external Ca2+ was replaced by Ba2+, indicating that some part of the mechanism underlying the current suppression is Ca2+ dependent. Because mGluR stimulates phosphoinositide turnover and release of Ca2+ from intracellular stores in other types of neurons, the possibility of released Ca2+ mediating inactivation of Ca2+ channels was considered. However, the Ca2+ current suppression was not attenuated by strong intracellular Ca2+ buffering [20 mM bis-(o-aminophenoxy)-N,N,N',N'-tetraacetic acid (BAPTA)], by dialysis with 100 microM inositol-1,4,5-triphosphate (IP3), or by external application of 1 microM thapsigargin. 5. We conclude that in neocortical neurons, one action of mGluR is to suppress the component of high-threshold Ca2+ current conducted by L-type Ca2+ channels.(ABSTRACT TRUNCATED AT 400 WORDS)

scholarly journals Long-term regulation of calcium channels in clonal pituitary cells by epidermal growth factor, insulin, and glucocorticoids.

1994 ◽  
Vol 104 (6) ◽  
pp. 1019-1038 ◽  
Author(s):  
U Meza ◽  
G Avila ◽  
R Felix ◽  
J C Gomora ◽  
G Cota
Keyword(s):  
Growth Factor ◽  
Epidermal Growth Factor ◽  
Current Density ◽  
Threshold Current ◽  
Gh3 Cells ◽  
High Threshold ◽  
Ca Channels ◽  
Regulatory Factors ◽  
Epidermal Growth ◽  
Low Threshold

In rat pituitary GH3 cells, epidermal growth factor (EGF) and insulin stimulate prolactin production, whereas glucocorticoids exert the opposite effect. In the present study, GH3 cells were subjected to whole-cell patch clamp to assess the chronic actions of such regulatory factors on voltage-dependent calcium currents. Before the electrical recording, cells were grown 5-6 d either under standard conditions or in the presence of 5 nM EGF, 100 nM insulin, 1 microM dexamethasone or 5 microM cortisol. EGF induced a twofold selective increase in high-threshold calcium current density. Insulin and glucocorticoids, on the other hand, specifically regulated low-threshold Ca channels. Current density through these channels increased by 70% in insulin-treated cells, and decreased by 50% in cells exposed to dexamethasone or cortisol. Other Ca channel properties investigated (conductance-voltage curves, deactivation rates, time course and voltage dependence of low-threshold current inactivation) were unaffected by the chemical messengers. The alterations in current density persisted for many hours after removing the regulatory factors from the culture medium. In fact, the stimulatory action of EGF on high-threshold current lasted &gt; 3 d. The results suggest that the control of prolactin production by the factors tested involves regulation of the surface density of functional Ca channels in the plasma membrane.

Protein kinase activator 1-oleoyl-2-acetyl-sn-glycerol inhibits two types of calcium currents in GH3 cells

1988 ◽  
Vol 254 (1) ◽  
pp. C206-C210 ◽  
Author(s):  
C. Marchetti ◽  
A. M. Brown
Keyword(s):  
Protein Kinase ◽  
Chick Embryo ◽  
Calcium Currents ◽  
Gh3 Cells ◽  
High Threshold ◽  
Pituitary Cells ◽  
Excitable Cells ◽  
Whole Cell ◽  
Whole Cell Patch Clamp ◽  
Low Threshold

Two types of Ca2+ currents, high-threshold, long-lasting, or L currents and low-threshold, transient, or T currents, are present in many excitable cells. L-type Ca2+ current is modulated by, among others, beta- and alpha-adrenoreceptors and intracellular Ca2+, but modulation of T-type Ca2+ current is less well established. 1-Oleoyl-2-acetyl-sn-glycerol (OAG), a synthetic activator of protein kinase C (PKC), modulates whole cell Ca2+ currents in a variety of excitable cells. Whether activators of PKC affect preferentially L and T types of Ca2+ currents is unknown. We tested OAGs effects on whole cell Ca2+ currents in the clonal GH3 line of anterior pituitary cells. The currents were measured using the whole cell patch-clamp method. Four to 60 microM OAG reversibly reduced Ca2+ currents produced by test potentials to 10 mV, and the inhibition was half maximal at approximately 25 microM. Such concentrations depress Ca2+ currents in chick embryo dorsal root ganglion (DRG) cells and clonal AtT-20 pituitary cells. To test whether OAG acted preferentially on L or T current, we separated the two using depolarizing prepulses to inactivate T current. OAG (40 microM) attenuated T currents by 60% and L currents by 50%. The current waveforms were not changed and were simply scaled, and the effects on both occurred approximately 15 s after OAG was applied. In chick embryo DRGs OAG inhibited the T current by 30% and the L current by 50%. We conclude that PKC modulates Ca2+ currents by acting on both L and T Ca2+ channels.

scholarly journals Pharmacological assessment of the contribution of the arterial baroreflex to sympathetic discharge patterns in healthy humans

2018 ◽  
Vol 119 (6) ◽  
pp. 2166-2175 ◽  
Author(s):  
Jacqueline K. Limberg ◽  
Elizabeth P. Ott ◽  
Walter W. Holbein ◽  
Sarah E. Baker ◽  
Timothy B. Curry ◽  
...  
Keyword(s):  
Blood Pressure ◽  
Arterial Blood Pressure ◽  
Sympathetic Activity ◽  
High Threshold ◽  
Neural Activation ◽  
Afferent Activity ◽  
Cluster Number ◽  
Arterial Blood ◽  
Rate Coding ◽  
Low Threshold

To study how changes in baroreceptor afferent activity affect patterns of sympathetic neural activation, we manipulated arterial blood pressure with intravenous nitroprusside (NTP) and phenylephrine (PE) and measured action potential (AP) patterns with wavelet-based methodology. We hypothesized that 1) baroreflex unloading (NTP) would increase firing of low-threshold axons and recruitment of latent axons and 2) baroreflex loading (PE) would decrease firing of low-threshold axons. Heart rate (HR, ECG), arterial blood pressure (BP, brachial catheter), and muscle sympathetic nerve activity (MSNA, microneurography of peroneal nerve) were measured at baseline and during steady-state systemic, intravenous NTP (0.5–1.2 µg·kg−1·min−1, n = 13) or PE (0.2–1.0 µg·kg−1·min−1, n = 9) infusion. BP decreased and HR and integrated MSNA increased with NTP ( P < 0.01). AP incidence (326 ± 66 to 579 ± 129 APs/100 heartbeats) and AP content per integrated burst (8 ± 1 to 11 ± 2 APs/burst) increased with NTP ( P < 0.05). The firing probability of low-threshold axons increased with NTP, and recruitment of high-threshold axons was observed (22 ± 3 to 24 ± 3 max cluster number, 9 ± 1 to 11 ± 1 clusters/burst; P < 0.05). BP increased and HR and integrated MSNA decreased with PE ( P < 0.05). PE decreased AP incidence (406 ± 128 to 166 ± 42 APs/100 heartbeats) and resulted in fewer unique clusters (15 ± 2 to 9 ± 1 max cluster number, P < 0.05); components of an integrated burst (APs or clusters per burst) were not altered ( P > 0.05). These data support a hierarchical pattern of sympathetic neural activation during manipulation of baroreceptor afferent activity, with rate coding of active neurons playing the predominant role and recruitment/derecruitment of higher-threshold units occurring with steady-state hypotensive stress. NEW & NOTEWORTHY To study how changes in baroreceptor afferent activity affect patterns of sympathetic neural activation, we manipulated arterial blood pressure with intravenous nitroprusside and phenylephrine and measured sympathetic outflow with wavelet-based methodology. Baroreflex unloading increased sympathetic activity by increasing firing probability of low-threshold axons (rate coding) and recruiting new populations of high-threshold axons. Baroreflex loading decreased sympathetic activity by decreasing the firing probability of larger axons (derecruitment); however, the components of an integrated burst were unaffected.

scholarly journals Genomics, Exometabolomics, and Metabolic Probing Reveal Conserved Proteolytic Metabolism of Thermoflexus hugenholtzii and Three Candidate Species From China and Japan

2021 ◽  
Vol 12 ◽  
Author(s):  
Scott C. Thomas ◽  
Devon Payne ◽  
Kevin O. Tamadonfar ◽  
Cale O. Seymour ◽  
Jian-Yu Jiao ◽  
...  
Keyword(s):  
United States ◽  
Amino Acids ◽  
Draft Genome ◽  
The United States ◽  
Pentose Phosphate ◽  
High Abundance ◽  
Comparative Genomic ◽  
Labeled Compounds ◽  
Geothermal Systems

Thermoflexus hugenholtzii JAD2T, the only cultured representative of the Chloroflexota order Thermoflexales, is abundant in Great Boiling Spring (GBS), NV, United States, and close relatives inhabit geothermal systems globally. However, no defined medium exists for T. hugenholtzii JAD2T and no single carbon source is known to support its growth, leaving key knowledge gaps in its metabolism and nutritional needs. Here, we report comparative genomic analysis of the draft genome of T. hugenholtzii JAD2T and eight closely related metagenome-assembled genomes (MAGs) from geothermal sites in China, Japan, and the United States, representing “Candidatus Thermoflexus japonica,” “Candidatus Thermoflexus tengchongensis,” and “Candidatus Thermoflexus sinensis.” Genomics was integrated with targeted exometabolomics and 13C metabolic probing of T. hugenholtzii. The Thermoflexus genomes each code for complete central carbon metabolic pathways and an unusually high abundance and diversity of peptidases, particularly Metallo- and Serine peptidase families, along with ABC transporters for peptides and some amino acids. The T. hugenholtzii JAD2T exometabolome provided evidence of extracellular proteolytic activity based on the accumulation of free amino acids. However, several neutral and polar amino acids appear not to be utilized, based on their accumulation in the medium and the lack of annotated transporters. Adenine and adenosine were scavenged, and thymine and nicotinic acid were released, suggesting interdependency with other organisms in situ. Metabolic probing of T. hugenholtzii JAD2T using 13C-labeled compounds provided evidence of oxidation of glucose, pyruvate, cysteine, and citrate, and functioning glycolytic, tricarboxylic acid (TCA), and oxidative pentose-phosphate pathways (PPPs). However, differential use of position-specific 13C-labeled compounds showed that glycolysis and the TCA cycle were uncoupled. Thus, despite the high abundance of Thermoflexus in sediments of some geothermal systems, they appear to be highly focused on chemoorganotrophy, particularly protein degradation, and may interact extensively with other microorganisms in situ.

Sign in / Sign up

Export Citation Format

Share Document