Spatial Separation of Ancestral Genomes in the Wild Grass Milium montianum Parl.

Previous work showed a strong tendency for genomes from twodifferent parents to be spatially separated in cell nuclei ofseveral man-made F₁ hybrids between grass species. An importantquestion therefore is whether similar nonrandom genome dispositionoccurs in wild species. Milium montianum Parl. (2n = 22) isa naturally occurring allopolyploid grass combining two geneticallydissimilar chromosome sets (V and M genomes), each originatingfrom a different ancestral species. These two ancestral genomeswere easily discriminated as all V genome chromosomes were largerthan all M genome chromosomes. In two-dimensional spread preparations,the V genome derived from M. vernale Bieb. (2n = 8), and theM genome (of different but uncertain origin) showed a highlysignificant tendency to lie apart. Generally, the V chromosomestended to surround the M chromosomes in both mitotic and meioticnuclei suggesting that this arrangement persists throughoutplant development. Such nuclear organization is probably undergenetic control and may facilitate some independent behaviourof ancestral genomes in allopolyploids. Indeed it may play asignificant role in plant evolution and speciation, especiallyif different intranuclear positions (e.g. central or peripheral)are correlated with preferential phenotypic expression of ancestralgenes. Milium montianum Parl., Gramineae, allopolyploid, spatial chromosome disposition, ancestral genome separation, plant speciation and evolution     

Specific Daylength Effects on Leaf Growth and Dry-matter Production in High-latitude Grasses

Plants of Phleum pratense L. cv. Engmo (origin 69° N) andBromus inermis Leyss. cv. Löfar (origin 64° N) raisedin short days gave large and significant increases in d. wt,height and leaf area upon exposure to continuous light, comparedwith 8 h short days, at essentially identical daily inputs ofradiant energy (8 h summer daylight ± low intensity extension).The increases in both plant height and leaf area were causedmainly by increases in the dimensions of the leaf sheaths andblades, which, in turn, were the result of increased cell sizeand number. However, there was a pronounced interaction betweentemperature and daylength such that the greatest photoperiodicstimulation occurred at lower growing temperatures (     

COMPARATIVE KARYOLOGICAL ANALYSIS OF FIVE SPECIES OF VIVIPARUS (GASTROPODA: PROSOBRANCHIA)

Karyological analysis was performed on Viviparus ater (Cristofori& Jan, 1832), V. acerosus Bourguignat, 1862, V. mamillatus (Kuster),V. viviparus (Linnaeus, 1758) and V. contectus (Millet, 1813),collected from different freshwater bodies of Switzerland, Hungary,Albania, Italy and Lithuania. The karyotypes of V. acerosusand V. mamillatus are described for the first time. The diploidnumber of chromosomes in V. contectus equals 14, whereas indiploid sets of other studied species, 18 chromosomes are present.The karyotype formula is in V. contectus (5m + 2sm, NF = 28,in V. ater, 7m + 1sm-m + 1 sm, in V. acerosus and V. viviparus,8m + 1sm, NF = 36, in V. mamillatus, 6m + 1m-sm + 1sm-m + 1sm,NF = 36. In females of V. ater, V. mamillatus and V. acerosus,the heteromorphism of chromosome pair no. 8 was observed, witha sex-determining mechanism — ZW female /ZZ male. Although,Z and W chromosomes are metacentric, significant differences(P > 0.05, or P > 0.001) in their size were determined.The interspecific significant differences (P > 0.05) in karyotypesof V. ater, V. mamillatus, V. acerosus and V. viviparus weredetected by using one-way ANOVA and Bonferronis Multiple Comparisontests. Only chromosomes of the pair no. 5 were of similar shapein all of these species. The smallest interspecific differencewas between V. viviparus and V. acerosus. The intraspecifickaryological differences in relative chromosome length and centromericindex of V. contectus from lakes Garda (Italy), Olauka andAsveja (Lithuania) were observed in the chromosome pair no.5. (Received 29 March 1999; accepted 19 October 1999)     

The Hybrid Origin of Two Cultivars of Crocus (Iridaceae) Analysed by Molecular Cytogenetics including Genomic Southern and in situ Hybridization

The origin of the two common cultivars of Crocus, C. 'Stellaris'(2n = 2x = 10) and C. 'Golden Yellow' (2n = 3x = 14) was investigatedby fluorescent in situ hybridization using both total genomicDNA and cloned DNA sequences as probes. The clear differentiationbetween the chromosomes after genomic in situ hybridizationsupports the proposals of a hybrid origin of the cultivars andshows that they have the same parental genomes originating fromC. flavus (2n = 8) and C. angustifolius (2n = 12). C. 'Stellaris'has four chromosomes of C. flavus origin and six chromosomesof C. angustifolius origin. C. 'Golden Yellow' has eight chromosomesof C. flavus origin and six chromosomes of C. angustifoliusorigin. The number and location of 18S-5·8S-26S rRNAgenes on the chromosomes of the hybrids and of the parentalspecies agree with the results from the genomic probings. Hybridizationto Southern membranes also supports the hybrid origin of C.'Golden Yellow'.Copyright 1995, 1999 Academic Press Taxonomy, cytology, rDNA sites, in situ hybridization, Southern hybridization, Crocus     

Effects of Daylength on Floral Characteristics of Six White Clover (Trifolium repens) Varieties

The effect of daylength upon floral initiation, flower position,and associated features was measured in six white clover (Trifoliumrepens) varieties Most plants initiated flowers in the longest days (16 h). Thevarieties of more southerly origin and with large leaves hada greater spread of response to daylength. Increasing daylength increased the number of buds becoming inflorescencesin all varieties except Milkanova in which the reverse was true.Peduncle length and nectar production were both greatest inthe longest days. Trifolium repens, white clover, daylength, flower initiation, flower position     

Effect of Verticillium dahliae on Photosynthesis, Leaf Expansion and Senescence of Field-grown Sunflower

On the basis of known sunflower (Helianthus annuus L.) responsesto soil water deficit, it is proposed that the effect of thefungus Verticillium dahliae Klebahn on plant leaf area precedesand is greater than its effect on leaf photosynthesis and stomatalconductance. To test this hypothesis, we measured shoot andleaf area growth, leaf photosynthetic rate, stomatal conductanceand disease symptoms in a field experiment including hybridsof high (Sankol) and low (Dekasol 3900) susceptibility to V.dahliae. Plants inoculated with V. dahliae and controls werecompared. We also investigated the effect of V. dahliae on keycomponents of plant leaf area, leaf expansion and senescence,in inoculated and control plants of Sankol and Toba, a hybridof intermediate susceptibility to V. dahliae. Reduction in plantleaf area caused by V. dahliae was first detected 31 d afterinoculation (DAI), when visual symptoms of disease in inoculatedplants were slight (Sankol) or absent (Dekasol 3900). Reductionin leaf photosynthesis was first observed 66 DAI; stomatal conductanceand leaf dark respiration were both unaffected by V. dahliaeduring the whole experiment. In comparison with controls, V.dahliae reduced seasonal duration of plant leaf area by 25%in Dekalb 3900 and by 55% in Sankol, whereas the average reductionin leaf photosynthetic rate was 9%. In correspondence with thereduction in leaf area duration, inoculation reduced shoot drymatter of mature Sankol by 50%. In both experiments, less leafexpansion accounted for most of the early reduction in plantleaf area; as the disease progressed, increasing senescencealso contributed to reduced plant leaf area. It is concludedthat the response of sunflower to V. dahliae resembled the responseof the plant to soil water deficit: (1) plant leaf area, ratherthan leaf photosynthetic rate, accounted for the reduction ingrowth in mass; and (2) reduced leaf expansion early in theseason and faster leaf senescence in older plants accountedfor the decrease in plant leaf area. Copyright 2000 Annals ofBotany Company Helianthus annuus, Verticillium dahliae, allometry, apical dominance, drought, leaf expansion, leaf senescence, photosynthesis, stomatal conductance, growth     

Karyotype, DNA Content and Meiotic Behaviour in Five South American Species ofVicia(Fabaceae)

This paper presents the karyotype, DNA content and meiotic behaviourof five species ofViciafrom Argentina (V. macrogramineaBurk.,V.gramineaSM.,V. epetiolarisBurk.,V. pampicolaBurk. andV. nanaVog.).All the species have the same chromosome number and karyotypeformula (2n=14; 6m+4st+4t). Each species, however, displaysa characteristic number and position of the nucleolar organizerregion (NOR) and different sizes of the respective satellites,confirmed by Ag-NOR banding. Moreover, significant differenceswere found in the total chromosome volume (TCV) and DNA contentof the species. Positive correlations between DNA content andTCV, and between DNA content and type of life cycle were alsofound. TCV and DNA content are lower inV. nana(annual) and higherinV. macrograminea(biennial–perennial). The material displayedmarked karyotypic orthoselection, with similar karyotypes inall studied species, even when the overall chromosome size varied.Evolutionary changes in DNA amount are proportional to the relativelength of each chromosome arm, maintaining karyotypic uniformity.Significant differences were found between the meiotic behaviourofV. gramineaand that of the other species.V. gramineahas alower frequency of ring bivalents and chiasmata per cell, andalso has a lower interstitial chiasma frequency. In general,the results are congruent with the morphological data reportedfor these species.Copyright 1998 Annals of Botany Company. Viciaspecies, karyotype, orthoselection, nuclear DNA content, NOR banding, meiotic behaviour.     

Mannose Binding Lectins of Vicia tetrasperma Seed and Their Immunological Relationship to Other Legume Lectins of Similar Specificity

Mannose specific lectins of Vicia tetrasperma were purifiedby affinity chromatography with Sephadex G-100, and ion exchangechromatography. Chromatofocusing using PBE-94 gel was successfullyemployed to separate the major isolectins, lectin I and II.Both lectins had the same molecular weight of 78,000 and weretetramers composed of a uniform subunit with a molecular weightof 18,700. Amino acid compositions of these lectins were quitesimilar to each other, rich in aspartic acid (and/or asparagine)and hydroxyl amino acids, and lacking methionine and cysteine.Agar gel double diffusion using anti V. tetrasperma lectin antiserumrevealed that lectins from V. cracca, Pisum sativum, and Lensculinaris, all of which have mannose binding properties, wereantigenically identical. The antiserum reacted with the analogouslectins from V.faba, V. hirsuta, and V. angustifolia, but formationof a spur in the diffusion assay showed that they were slightlydifferent from V. tetrasperma lectin. (Received December 24, 1985; Accepted March 12, 1986)     

黄荆精油对玉米象的杀虫活性成分、毒力及作用机制

为明确黄荆精油及其主要成分作为储粮保护剂的开发利用价值,采用水蒸气蒸馏法从泰山黄荆Vitex negundo Linn.叶片中提取精油,利用GC-MS技术进行了成分分析鉴定,研究了黄荆精油及其主要成分桉树脑和α-蒎烯对玉米象 Sitophilus zeamais Motschulsky 成虫的毒力及作用机制。结果表明: 黄荆精油中含量大于0.3%的成分有31种,其中石竹烯、桉树脑和α-蒎烯的含量分别为35.97%,8.21%和0.69%。桉树脑、α-蒎烯和黄荆精油对玉米象成虫的综合杀虫毒力都较高,并以桉树脑的毒力最高,LC₅₀为0.7171 g·kg^-1;在2.0 g·kg^-1剂量下,桉树脑、α-蒎烯和黄荆精油对玉米象种群的抑制率分别达100％,85.45％和89.73％;3种药剂对玉米象72 h触杀LC₅₀分别为0.2690,0.7529 和0.2969 mg·cm^-2,毒力都很高;3种药剂在4 g·kg^-1剂量下,对玉米象的驱避率分别为96.49%,84.26％和90.61%,防虫作用大;3种药剂对玉米象72 h的熏蒸LC₅₀分别为14.053, 28.648 和21.429 μL·L^-1,熏蒸杀虫毒力较高,其中以桉树脑的毒力最高。3种药剂对玉米象有干扰呼吸的作用,对离体乙酰胆碱酯酶、过氧化氢酶和羧酸酯酶都有抑制作用。这些结果明黄荆精油及其主要成分的作用机制具有多样性。     

Effects of Photoperiod and Temperature on Shoot, Root and Rhizome Growth in ThreeLotus uliginosusSchkuhr Populations

The growth of three populations of greater lotus (Lotus uliginosusSchkuhrsyn.L. pedunculatusCav.) was compared at photoperiods of 10,12 and 14 h at a maximum day/minimum night temperature of 21/16°C and at maximum day/minimum night temperatures of 27/22,21/16, 18/13 and 15/10 °C at a photoperiod of 12 h. Shortdays (10 h) favoured root and rhizome development compared tolong days (14 h). A temperature regime of 15/10 °C restrictedrhizome development compared to the 18/13 and 21/16 °C regimes.Shoot growth was restricted at the highest temperature regime(27/22 °C). The cultivar Sharnae had fewer, but heavier,rhizomes than Grasslands Maku; this may indicate adaptationto the dry summers at its site of origin (Algarve, Portugal).The response of rhizome growth to temperature and photoperiodexplains part of the performance of greater lotus in the fieldat a wide range of latitudes. Grazing management to encouragethe persistence ofL. uliginosusin pasture in temperate environmentsmay include the exclusion of grazing livestock in autumn. Inthe sub-tropics, monitoring of rhizome production in the fieldwould be required before deciding the appropriate time intervalbetween grazing.Copyright 1998 Annals of Botany Company Lotus uliginosus(Schkuhr); greater lotus; temperature; daylength; shoots; roots; rhizomes.     

Graft Transmission of Longday-induced Leaf Senescence in Kleinia articulata

Kulkarni, V. J. and Schwabe, W. W. 1985 Graft transmission oflongday-induced leaf senescence in Kleinia articulata.—J.exp. Bot. 36: 1620–1633. Senescence of attached and detached rooted leaves in Kleiniaarticulata can be regulated by daylength, accelerated by longphotoperiods LD (> 16 h) and retarded by short days SD (8h). Using detached, rooted leaves as stocks in leaf to leafgrafts, senescence was readily transmitted from a LD donor leafto a SD receptor leaf even if the receptor was retained in SD(D8).However, no transfer could be detected where it had to passthrough any stem tissue. Senescence was reversible up to a certain stage, beyond whichgrafts senesced, pointing to an accumulation of the graft transmissiblefactor to a threshold level that causes irreversible death. Key words: Kleinia, leaf senescence, senescence factor, daylength, graft transmission     

Endogenous Levels of Gibberellins, IAA and Cytokinins in Catharanthus Crown Gall Tissues of Different Tumor Types

Endogenous levels of gibberellins, auxins and cytokinins incrown gall tissues of Catharanthus roseus G. Don. (Vinca roseaL.) of two different tumor types, induced by a nopaline-typeand an octopine-type Ti-plasmid, were examined. The levels of gibberellins were higher in nopaline-type V208cells than in octopine-type V277 cells. GA₁₂ and GA₂₄ were identifiedfrom V208 cells. The level of IAA was 20-fold higher in V208cells than in V277 cells. The level of trans-ribosylzeatin washigher in V277 cells than in V208 cells, whereas trans-zeatinwas present at higher levels in V208 cells than in V277 cells. Our results revealed that the production of gibberellins, aswell as of IAA and cytokinins, in the crown gall tissues ofCatharanthus roseus differed between the octopine- and nopaline-typetumors, even though the crown galls apparently grow as unorganizedaggregates of cells in both cases. ⁴Present address: Facultad de Ciencias, Pontificia UniversidadJaveriana, Bogota, Colombia. (Received September 29, 1989; Accepted February 2, 1990)     

Flowering Behaviour of Four Annual Grass Species in Relation to Temperature and Photoperiod

Populations of four co-habiting annual grass species Bromusmollis L. (Soft brome), Hordeum hystrix Roth (Mediterraneanbarley grass), Lolium rigidum Gaud. (Wimmera ryegrass) and Vulpiabromoides (L.) S. F. Gray (Squirrel-tail fescue) were examinedfor the presence and comparative levels of vernalization andphotoperiod response. This was evaluated as the number of daysfrom sowing to heading in both long (16 h) and short (normal,over-winter) photoperiods at two levels of temperature. Wide variation among the species in both vernalization and photoperiodicresponse was detected. L. rigidum possessed a high level ofvernalization response and was comparatively sensitive to photoperiodwhile V. bromoides possessed little or no vernalization responseand was comparatively insensitive to photoperiod. B. mollisand H. hystrix appeared to be intermediate between these twospecies for both responses. There were wide differences in timeto heading under long photoperiod (16 h) and high temperature(20 °C) of plants derived from seed of three of the speciesripened under non-vernalizing temperatures. This variation indicatesthe likely existence of genetic differences in vernalizationresponse between plants of these populations. The implications of these findings to the adaptability of thesespecies to the Australian environment have been outlined. Bromus mollis L., soft brome, Hordeum hystrix Roth, Mediterranean barley grass, Lolium rigidum Gaud, Wimmera ryegrass, Vulpia bromoides (L.) S. F. Gray, Squirrel-tail fescue, flowering, vernalization, photoperiod, temperature     

GENETIC VARIATION IN SYMPATRIC AND ALLOPATRIC POPULATIONS OF HYBRIDIZING FRESHWATER SNAIL SPECIES(VIVIPARUS ATER AND V. CONTECTUS)

To estimate the geographical extent of introgression, we studiedthe genetic structure of sympatric and allopatric populationsof hybridizing freshwater snail species Viviparus ater and V.contectus in central Europe. Six allozyme loci which were variablein Lake Garda, Italy in a previous study (five nearly diagnosticloci between the two species and one highly polymorphic locusin V. contectus) were analyzed from ten sympatric locationsand four allopatric populations each for the two species. Presumablyintrogressed genes (low allele frequencies) were found fromat least one locus in seven out of the ten sympatric sites.These seven sites covered most of northern Italy. The data indicatethat introgression has occurred from Viviparus contectus toV. ater and vice versa. Therefore, there is a possibility ofwidespread introgression or mosaic zones in nature. However,we cannot rule out that the observed patterns are due to theshared ancestry. V. ater possessed low genetic variation (thejackknifed mean of Wright's F_ST±S.E. over four loci was0.041±0.004). On the other hand, V. contectus showedhigh genetic differentiation (the jackknifed mean of F_ST±S.E. over six loci was 0.546±0.166). Although introgressionmay have caused evolutionary changes in V. ater and V. contectus,it was not strong enough to level out the genetic differencesbetween the two species, which may have originated from isolationamong populations in V. contectus and a past bottleneck eventin V. ater. (Received 21 June 1996; accepted 31 January 1997)     

Vascular and General Anatomy of the Rootstocks of Three Stemless Viola Species

The primary vascular system of the rootstock of Viola rotundifolia,V. odorata and V. cucullata consists of an open system of threesympodia, corresponding to three orthostichies (parastichies)of leaves in the 1 /3 phyllotaxy. Between the major, collateralbundles there are vascular strands consisting of only primaryphloem. The vascular supply to axillary buds developing in thefirst season of growth is the same in flowering and vegetativebuds and there is a homology between the bracts on the pedunclesof axillary flowers and the prophylls of the axillary vegetativebranches. The overwintering portions of the rootstocks are somewhatwoody. The uneven development of secondary xylem correspondsto the locations of the sympodia. Secondary xylem closes a leafgap of a median trace only slowly, but any gap in the phloicsystem is closed quickly by secondary growth. Viola rotundifolia, V. odorata, V. cucullata, rootstock, vascular anatomy     

Evidence for an outcrossing reproductive strategy in the hermaphroditic heterobranch gastropod Valvata utahensis (valvatidae), with notes on the genetic differentiation of V. utahensis and V. humeralis

The hermaphroditic aquatic heterobranch Valvata utahensis isa federally endangered snail endemic to the Snake River corridorin southern Idaho, USA. Although an appreciable understandingof molluscan taxonomic diversity has been established withinthis ecosystem, little is currently known about the ecologyand life history of many individual species (V. utahensis included).In this study, we used a combined analysis of mitochondrialand nuclear genetic variation within V. utahensis to infer thepredominant mode of reproduction (selfing vs outcrossing) withinnatural populations of this species. Results of this analysisindicated that outcrossing is likely a common reproductive strategy.We discuss our results in the context of conservation and managementefforts for this endangered species. Furthermore, in the courseof performing our investigations, we frequently collected specimensthat were tentatively identified as V. humeralis. Given thatlittle genetic work has previously been performed within thegenus Valvata, we compared genetic data from V. utahensis withdata from V. humeralis to determine whether molecular data supportedmorphological evidence that these two taxa are distinct evolutionaryentities. Results of our analyses clearly revealed strong patternsof genetic differentiation between these two taxa and confirmedthe presence of two sympatric Valvata species within the SnakeRiver system. (Received 25 January 2006; accepted 20 April 2006)     

Monitoring Primary Response to Chilling Stress in Etiolated Vigna radiata and V. mungo Seedlings Using Thermal Hysteresis of Water Proton NMR Relaxation Times

Thermal hysteresis of longitudinal relaxation times (T₁) ofwater protons in hypocotyls of etiolated Vigna radiata and V.mungo seedlings was investigated by pulse nuclear magnetic resonance(NMR) spectroscopy. Various lengths of chilling exposures duringa cool-warm cycle between 20 and 0?C (below 10?C, about 4 h)for the T₁ hysteresis measurement did not cause any visibleinjury symptoms in hypocotyls. However, the profiles of T₁ hysteresisvaried as a result of different chilling exposures. The sumsof the T₁ ratio (for detail see Introduction) reflecting T₁prolongation or shortening upon the warming process were a goodquantitative index for the extent of T₁ hysteresis, and thewide dispersion of this value ranging on the "minus" side (T₁prolongation upon warming) suggested the occurrence of a primaryresponse of cells to chilling stress before obvious visiblesymptoms occur while the T₁ ratio sums on the "plus" side (T₁shortening upon warming) corresponded to a response of seriousvisible injury. Therefore, the sums of the T₁ ratio can be usedas a non-destructive diagnostic tool for monitoring the primaryevent of chilling injury when lacking any visible injury symptoms.The data indicate that the critical temperature for the occurrenceof primary response for chilling stress was around 7.5?C forV. radiata and 12.5?C for V. mungo. (Received February 1, 1988; Accepted June 1, 1988)     

Human ventilatory response to 8h of euoxic hypercapnia

Tansley, John G., Michala E. F. Pedersen, Christine Clar,and Peter A. Robbins. Human ventilatory response to 8 h of euoxic hypercapnia. J. Appl.Physiol. 84(2): 431-434, 1998.Ventilation (E) risesthroughout 40 min of constant elevated end-tidalPCO₂ without reaching steady state(S. Khamnei and P. A. Robbins. Respir. Physiol. 81: 117-134, 1990). The present studyinvestigates 8 h of euoxic hypercapnia to determine whetherE reachessteady state within this time. Two protocols were employed:1) 8-h euoxic hypercapnia (end-tidalPCO₂ = 6.5 Torr above prestudy value,end-tidal PO₂ = 100 Torr) followed by 8-h poikilocapnic euoxia; and2) control, where the inspired gaswas air. Ewas measured over a 5-min period before the experiment and then hourly over a 16-h period. In the hypercapnia protocol,E had notreached a steady state by the first hour(P < 0.001, analysis of variance), but there were no further significant differences inEover hours 2-8 (analysis ofvariance). Efell promptly on return to eucapnic conditions. We conclude that,whereas there is a component of theE responseto hypercapnia that is slow, there is no progressive rise inE throughoutthe 8-h period.

     

Functional characterization of voltage-gated K+ channels in mouse pulmonary artery smooth muscle cells

Mice are useful animal models to study pathogenic mechanisms involved in pulmonary vascular disease. Altered expression and function of voltage-gated K⁺ (K_V) channels in pulmonary artery smooth muscle cells (PASMCs) have been implicated in the development of pulmonary arterial hypertension. K_V currents (I_K(V)) in mouse PASMCs have not been comprehensively characterized. The main focus of this study was to determine the biophysical and pharmacological properties of I_K(V) in freshly dissociated mouse PASMCs with the patch-clamp technique. Three distinct whole cell I_K(V) were identified based on the kinetics of activation and inactivation: rapidly activating and noninactivating currents (in 58% of the cells tested), rapidly activating and slowly inactivating currents (23%), and slowly activating and noninactivating currents (17%). Of the cells that demonstrated the rapidly activating noninactivating current, 69% showed I_K(V) inhibition with 4-aminopyridine (4-AP), while 31% were unaffected. Whole cell I_K(V) were very sensitive to tetraethylammonium (TEA), as 1 mM TEA decreased the current amplitude by 32% while it took 10 mM 4-AP to decrease I_K(V) by a similar amount (37%). Contribution of Ca²⁺-activated K⁺ (K_Ca) channels to whole cell I_K(V) was minimal, as neither pharmacological inhibition with charybdotoxin or iberiotoxin nor perfusion with Ca²⁺-free solution had an effect on the whole cell I_K(V). Steady-state activation and inactivation curves revealed a window K⁺ current between –40 and –10 mV with a peak at –31.5 mV. Single-channel recordings revealed large-, intermediate-, and small-amplitude currents, with an averaged slope conductance of 119.4 ± 2.7, 79.8 ± 2.8, 46.0 ± 2.2, and 23.6 ± 0.6 pS, respectively. These studies provide detailed electrophysiological and pharmacological profiles of the native K_V currents in mouse PASMCs. K_V channels