bluuebunny/crossref_metadata_2025 huggingface dataset:
Germination and establishment of halophytes on brine‐affected soils
Authors: Keiffer Carolyn Howes , Ungar Irwin A.
Published: March 2003

Contamination of soils with oilfield brines is a significant environmental problem in many oil‐production areas. This study tested the feasibility of using different salt‐accumulating halophyte species to remediate brine‐contaminated soils at a site in south‐eastern Ohio, USA, and tested whether planting season affected the germination, yield and sodium uptake of selected species.

Atriplex prostrata, Hordeum jubatum, Salicornia europaea, Spergularia marina and Suaeda calceoliformis were sown in October 1992 (autumn sowing) and March 1993 (spring sowing). For A. prostrata and Spergularia marina, spring‐sowing produced greater germination and survival, while H. jubatum exhibited greater germination and survival in autumn sowings. Germination and survival of Salicornia europaea and Suaeda calceoliformis were not significantly affected by sowing season, but Salicornia europaea germinated and survived poorly in both seasons.

Spring‐sown A. prostrata and Suaeda calceoliformis and autumn‐sown H. jubatum and Spergularia marina produced the greatest yields.

High soil conductivities negatively affected the survival and yield of spring‐sown A. prostrata, H. jubatum and Spergularia marina, but did not significantly affect autumn sowings.

Root biomass allocation was greater in autumn‐sown H. jubatum, Spergularia marina and Suaeda calceoliformis. We hypothesized that autumn‐sown seeds of these species have earlier root development that facilitates avoidance of extreme salinity and moisture fluctuations found at the soil surface.

All species accumulated higher amounts of Na+ and Cl− than other ions. Autumn‐sown A. prostrata and Suaeda calceoliformis accumulated significantly more Na+ than when spring‐sown. Ash content (a measure of accumulated inorganic matter) ranged from 15% to 35% in the various plant tissues. Hordeum jubatum had significantly more Na+ in its roots than in its shoots, making it less suitable for site remediation than A. prostrata or Suaeda calceoliformis.

With the exception of Salicornia europaea, all species reduced soil salinity significantly compared with paired control plots, ranging from 4% in H. jubatum to 17% in A. prostrata. Leaching following precipitation resulted in a 44% reduction in Na+ from control plots over a 4‐year period. However, there was a 59% reduction in Na+ from plots vegetated with halophytes over the same period.

The results indicate that establishment of salt‐accumulating halophytes on salt‐affected sites can sufficiently remediate the soil to the point where it can be returned to agricultural productivity or where native plants can invade and become established. The phytoremediation process can be facilitated by tailoring plant selection to site conditions, using inputs of fertilizer and water to enhance the growth of the halophytes, and by harvesting the plants on a regular basis.
Spectral analysis of intercycle heart fluctuations in the diethyl‐ether‐anaesthetized or pithed rat treated with prazosin, dl‐propranolol, endothelin‐1, α‐r atriopeptin and ACE‐inhibitors
Authors: Bernardi M. , Deslauriers R. , Docherty J. , Rossi C. , Rossini L. , Rossini P. , Tonnini C.
Published: March 2003

1 Frequency‐domain spectral analysis of stationary ECG R‐R intervals was made by fast Fourier transformation (FFT) in conditions of monitored arterial blood pressure and respiratory activity in diethyl‐ether‐anaesthetized and pithed adult rats. This technique yields a number of parameters which allow quantitative evaluation of the non‐random distribution of the mean values obtained in time‐domain studies. The frequency‐analysis method enables the overall heart rate variability to be broken down into its various constituents, which are differently affected by physiological loading and capable of selective reactivity to pharmacological agents.

2 The low‐frequency spectral component obtained by breaking down the total spectral density power, i.e. the appropriate variability signal (band width < 0.15 Hz) and a higher‐frequency band corresponding to spontaneous (0.80–1.60 Hz) or artificially imposed (0.75 Hz) respiratory activity were estimated and their integrated areas evaluated as absolute powers or normalized fractional values.

3 The power of the high‐frequency spectral component increased in all animal preparations under treatment with prazosin, dl‐propranolol, endothelin‐1 and the angiotensin converting enzyme (ACE) inhibitors captopril, lisinopril, quinapril and ramipril. The power of the low‐frequency band increased under α‐r atriopeptin and ACE inhibitors in the pithed preparations only, and decreased in the anaesthetized animals.

4 The new power spectrum features and trends detected indicate that these time‐independent, model‐dependent cardiovascular and respiratory markers are subject to some form of complex peptidergic control.

5 The relative roles of the various factors operating in the genesis of these short‐term changes in spectral power in the low‐ and high‐frequency bands cannot be interpreted as indicating a reciprocal push–pull relationship between sympathetic and parasympathetic control.

6 The study findings, however, can be interpreted as providing evidence of a different and to some extent alternative form of integrative cardiovascular control persisting in the pithed rats (i.e. in the ‘peripheral’, CNS‐destroyed preparations).

7 New areas of theoretical and applied research are being developed in the (auto)classification of (iso)receptors and drug analogues through exploration of multiple physiological and pharmacokinetic parameters in the frequency‐domain. Furthermore, model‐independent frequency‐domain methods not requiring stationary data will afford scope for even more significant developments by separating the overlapping dynamic processes from a whole series of correlated effects.
Effects of some imidazolidine α2‐adrenoceptor agonists in rat isolated atria
Authors: Thaina P. , Nott M. W. , Rand M. J.
Published: March 2003

1 The prejunctional α2‐adrenoceptor agonist activity of four imidazolidines (UK14819, UK14304, UK15121 and UK11957) were compared to that of clonidine in rat isolated atrial preparations.

2 The preparations consisted of spontaneously beating left and right atrial pairs that were incubated with [3H]‐noradrenaline. The efflux of radioactivity induced by electrical field stimulation of intramural sympathetic nerves was used as an index of neurotransmitter release and inotropic and chronotropic responses were recorded.

3 Two quinoxalinyl imidazolidines (UK14819 and UK14304 which have chloride and bromide substitution, respectively, in the phenyl moiety) caused decreases in the efflux of radioactivity with stimulation at 2 Hz and 10 Hz but not at 20 Hz. These effects were antagonised by the α2‐adrenoceptor antagonist idazoxan (0.3 μm) but they were not affected by the α1‐adrenoceptor antagonist prazosin (0.1 μm).

4 The third halogenated quinoxalinyl imidazolidine analogue (UK15121, which has an iodide substitution in the phenyl ring) and a quinolinyl imidazolidine (UK11957) have actions similar to clonidine. They decreased the efflux of radioactivity with stimulation at 1 Hz (for UK11957) or 2 Hz (for UK15121) and enhanced it at higher frequencies of stimulation. Both the inhibitory and enhancing effects were antagonised by idazoxan but they were not affected by prazosin.

5 Unlike the other three imidazolidines in the present study, the quinolinyl imidazolidine (UK11957), caused a decrease in resting release of radioactivity and this effect was prevented by the monoamine oxidase inhibitor pargyline (30 μm).

6 These findings suggest that the 5‐chloro‐or 5‐bromo substituted quinoxalinyl imidazolidines (UK14819 and UK14304) are full agonists at prejunctional α2‐adrenoceptors, but the 5‐iodo‐substituted quinoxalinyl imidazolidine (UK15121) and the quinolinyl analogue of UK14304 (UK11957), like clonidine, appear to be partial agonists at these receptors.
Effects of the chronic in vivo administration of L‐NAME on the contractile responses of the rat perfused mesenteric bed
Authors: Mendizabal V. E. , Feleder E. C. , Adler‐Graschinsky E.
Published: March 2003

1 The effects of the chronic in vivo inhibition of nitric oxide synthase (NOS) with Nω‐nitro‐
l‐arginine methyl ester (L‐NAME) on vascular contractility were studied in the rat perfused mesenteric bed. The chronic treatment with L‐NAME during 4 weeks induced a rise in systolic blood pressure (basal: 115.1 ± 6.5 mmHg; chronic L‐NAME treatment: 171.7 ± 7.7 mmHg, n = 16, P < 0.05).

2 After the chronic NOS inhibition, the potentiation of the maximal vasoconstrictor responses to noradrenaline, phenylephrine and KCl was to the same extent as that observed after the in vitro exposure to 100 μm L‐NAME.

3 No further potentiation of the contractile responses was achieved when the mesenteric beds isolated from L‐NAME treated rats were incubated in vitro with 100 μm L‐NAME.

4 The endothelium removal but not the inhibition of prostanoid synthesis with either 10 μm indomethacin or 10 μm 17‐octadecynoic acid potentiated the contractions to noradrenaline and to KCl both under control conditions as well as after the chronic in vivo administration of L‐NAME.

5 These observations taken together suggest that after chronic L‐NAME maximum inhibition of nitric oxide synthase was achieved and no compensatory mechanisms able to counterbalance the increase in contractile responses were developed.

6 Further studies are necessary to elucidate the nature of the factors, other than nitric oxide, that contribute to the potentiation of contractile responses observed when the endothelium is removed after L‐NAME treatment.
Differential blockade of α,β‐methylene‐ATP, noradrenaline and electrically evoked contractions of the rat vas deferens
Authors: Boselli C. , Grana E.
Published: March 2003

1 The present study was carried out compare the effects of nifedipine, verapamil, papaverine and chloroethylclonidine (CEC) on the electrically‐induced contractions and on the contractions produced by exogenous noradrenaline and α,β methylene‐ATP in the epidydimal portion of rat vas deferens.

2 Nifedipine inhibited in a concentration‐dependent fashion the purinergic component (phase I) of the electrically evoked response. Verapamil (10−−7 M−10−−5 M) did not inhibit significantly or even potentiated phase I of the contractile response to single‐pulse field stimulation but inhibited the response to α,β methylene‐ATP. Papaverine left unaffected phase I but depressed the response to α,β methylene‐ATP. CEC significantly potentiated the purinergic component of the electrically‐evoked response and the response induced by α,β methylene‐ATP.

3 Nifedipine was devoid of any inhibitory action on the noradrenergic component (phase II) of the response to single shock. Verapamil at the highest concentration used (10−−5 M) was able to partially inhibit phase II. Papaverine abolished in a concentration‐dependent manner the noradrenergic component of the response to single shock. CEC abolished the phase II of single shock while was devoid of any inhibitory action on exogenous noradrenaline.

4 The implications of these differences among the compounds studied in the present work are discussed in relation to roles of calcium channels.
Endothelium‐dependent vasodilatation mechanisms by histamine in simian but not in canine femoral arterial branches
Authors: Arai M. , Chiba S.
Published: March 2003

1 The vascular response of isolated, perfused canine and simian femoral arteries, which distribute blood to deep skeletal muscles, were investigated.

2 The vascular responses to histamine, 2‐pyridylethylamine (2‐PEA), dimaprit and α‐methylhistamine were pharmacologically analyzed in canine and simian vessels, using diphenhydramine (DPH, a histamine H1 receptor antagonist), cimetidine (a histamine H2 antagonist) and saponin which readily removed the endothelium.

3 In canine arteries, α‐methylhistamine showed no vascular response, but in simian preparations, it caused a slight vasoconstriction.

4 In canine arteries, histamine and 2‐PEA consistently induced a vasoconstriction in preconstricted and non‐preconstricted preparations. However, in simian arteries histamine usually produced a vasodilatation at small doses (less than 10−−7mol) and a vasoconstriction at large doses in preconstricted preparations.

5 Vasoconstrictor responses to histamine and 2‐PEA were significantly inhibited by DPH in both species. In simian vessels, histamine‐and dimaprit‐induced vasodilatations were significantly inhibited by cimetidine.

6 After removal of the endothelium by intraluminal treatment with saponin in canine femoral arteries, the vascular responses to histamine, 2‐PEA and dimaprit were not significantly affected. On the other hand, in simian femoral arteries, the vasodilatation responses to histamine and 2‐PEA were significantly depressed by the removal of endothelium.

7 It is concluded that (1) in both simian and canine femoral arterial branches, there are abundant histamine H1 and H2 receptors (2) in simian but not in canine arteries, there exist histamine H3 receptors, although their role is not clear (3) histamine induces a vasoconstriction mediated via histamine H1 receptors and a vasodilatation via H2 receptors which exist in vascular smooth muscle, and (4) in simian but not in canine arteries, there are endothelium‐dependent vasodilatation mechanisms.
Renal kallikrein‐kinin system, but not renal dopamine system, mediates the natriuretic response to intravenous saline infusion in healthy Chinese subjects
Authors: Chan T. Y. K. , Critchley J. A. J. H. , Ho C. S. , Tomlinson B. , Chan J. C. N. , Poon E. W. M. , Lee Z. S. K. , Critchley L. A. H. , Swaminathan R.
Published: March 2003

1 To assess the role of renal dopamine (DA), sympathetic nervous system (SNS) activity and the renal kallikrein‐kinin system in sodium excretion in Chinese subjects, we studied the effects of intravenous saline infusion on the urinary excretions of sodium, free DA, free noradrenaline (NA) and kallikrein in eight healthy males aged 23–25 years.  2 After a baseline period of 1 h (hour 0), these subjects received 1 l of 0.9% saline over 2 h (hours 1 and 2), followed by a 4‐h recovery period (hours 3–6). From hours 0–4, subjects remained in the supine position, except to void urine. Distilled water was given orally throughout the study to ensure an adequate diuresis.  3 A 31–39% increase in sodium excretion (P<0.05) was seen during hours 2 and 3. Urinary DA did not change throughout the study period. Urinary free NA showed no changes while the subjects remained supine, but an increase of 91–105% (P<0.02) was seen after the subjects became ambulatory. However, there was a 103–140% increase in urinary kallikrein excretion (P<0.05) during the saline infusion. Urinary kallikrein was still much higher (by 74%) than the basal level 1 h after the completion of the saline infusion.  4 There is no evidence from the present study that renal DA or SNS play any role in the natriuretic response to saline infusion in Chinese subjects. The brisk urinary kallikrein response, despite a relatively small salt load, suggests that the renal kallikrein‐kinin system may play an important role in extracellular fluid volume and sodium homeostasis in Chinese subjects.
Effects of eicosanoids and nitric oxide on the noradrenaline‐induced contractions in the rat mesenteric bed
Authors: Peredo H. A. , Adler‐Graschinsky E.
Published: March 2003

1 The effects of the inhibition of the metabolism of arachidonic acid (AA) on the constrictor responses to noradrenaline (NA) were studied in the rat perfused mesenteric bed. The inhibitor of all the pathways of AA metabolism, 10 μm eicosatetraynoic acid (ETYA), reduced the constrictor responses to all the concentrations of NA assayed.  2 The constrictor responses to NA were also reduced by the cyclooxygenase (COX) inhibitor, indomethacin (10 μm), as well as by the lipoxygenase inhibitor, nordihidroguaiaretic acid (1 μm; NDGA), whereas they were unmodified by the cytochrome P450 monooxigenase inhibitors, clotrimazole (10 μm), metyrapone (10 μm) and proadifen (10 μm).  3 The reduction in NA contractility induced by indomethacin was reverted with a decreasing order of potency by the thromboxane A2 analogue, U‐46619>prostaglandin (PG) E2>PGF2α. The exposure of the mesenteric bed to NA increased the production of PGF2α, whereas it did not modify the production of the remaining AA metabolites.  4 The increase in the NA‐induced contractions caused by endothelium removal, as well as by the inhibition of nitric oxide synthase (NOs) with NG‐nitro‐l‐arginine methyl ester (400 μm; L‐NAME), was suppressed by indomethacin but not by NDGA. These observations suggest that the lipoxygenase‐derived metabolites are formed in the endothelium, whereas the COX‐derived metabolites are formed in the vascular smooth muscle.  5 The TP receptor antagonist, SQ29548, did not modify the NA‐induced contractions, either in the presence or in the absence of the endothelium.  6 Contractions elicited by KCl (60–100 mm) were unmodified by the AA metabolism inhibitors, ETYA, NDGA and indomethacin.  7 In summary, these results show that metabolites of AA, through both the COX and the lipoxygenase pathways, are involved in the NA‐induced contractions in the rat mesenteric bed. The lipoxygenase metabolites are likely to be formed in the vascular endothelium, whereas the COX metabolite, which could be PGF2α, is apparently formed within the vascular smooth muscle.
Retracted: Dopamine receptor immunohistochemistry in the rat choroid plexus
Authors: Mignini F. , Bronzetti E. , Felici L. , Ricci A. , Sabbatini M. , Tayebati S. K. , Amenta F.
Published: March 2003

1 Earlier studies have demonstrated a high density of dopamine D1‐like receptor binding in the choroid plexus by light microscope autoradiography, but the dopaminergic specificity of this binding was questioned.

2 In this study the localization of dopamine receptor subtypes was investigated in the rat choroid plexus by Western blot analysis and immunohistochemistry using antibodies raised against dopamine D1–D5 receptor protein.

3 Western blot analysis revealed reactivity with immune bands of approximately 50 and 51 KDa corresponding to dopamine D1 and D5 receptors, respectively. Dopamine D1‐like (D1 and D5) receptor protein immunoreactivity insensitive to superior cervical ganglionectomy was located in smooth muscle of choroid arteries and to a larger extent within choroid plexus epithelium.

4 Western blot analysis revealed reactivity with immune bands of approximately 53 KDa and 40–42 KDa corresponding to dopamine D2 and D4 receptors, respectively, and no dopamine D3 receptor reactivity. Dopamine D2‐like receptor protein immunoreactivity displayed a distribution similar to that of tyrosine‐hydroxylase (TH)‐immunoreactive sympathetic fibres and disappeared after superior cervical ganglionectomy. It consisted in the expression of dopamine D2 and to a lesser extent of D4 receptor protein immunoreactivity perivascularly and associated with choroid epithelium. No D3 receptor protein immunoreactivity was found in rat choroid plexus.

5 The above results indicate that rat choroid plexus expresses dopamine receptor protein, being dopamine D1‐like receptors predominant in epithelium and arterial smooth muscle and D2‐like receptors in sympathetic nerve fibres supplying choroid plexus epithelium and vasculature.

6 These findings suggests that dopamine receptors with a different anatomical localization may modulate production of cerebrospinal fluid.
The minor population of M3‐receptors mediate contraction of human detrusor muscle in vitro
Authors: Chess‐Williams R. , Chapple C. R. , Yamanishi T. , Yasuda K. , Sellers D. J.
Published: March 2003

1 The objective was to determine the role of muscarinic receptor subtypes in mediating contraction of the human detrusor smooth muscle in vitro.

2 Contractile responses of human detrusor muscle strips to carbachol were obtained in the absence and presence of a range of muscarinic antagonists (pirenzepine, methoctramine, 4‐diphenylacetoxy‐N‐methyl piperidine methiodide (4‐DAMP), tropicamide, oxybutynin and tolterodine). Affinity estimates (pKB values) were calculated for the antagonists and correlated with values at the cloned muscarinic receptor subtypes quoted in the literature.

3 Pirenzepine, methoctramine and tropicamide drugs that have high affinities at M1, M2 and M4‐receptors, respectively, all had low affinities on the human detrusor (pKB values of 6.8, 6.9 and 6.5, respectively), whilst the M3‐selective antagonist 4‐DAMP had a high affinity (9.5). Schild plots for all four antagonists had slopes of unity indicating an action at a single receptor. Oxybutynin and tolterodine also acted as competitive antagonists with affinity estimates of 7.6 and 8.1, respectively.

4 When the antagonist affinities obtained on the bladder were plotted against the values published for these antagonists at the cloned muscarinic receptor subtypes, the best correlations were obtained for the m3‐ and m5‐muscarinic receptor subtypes.

5 These data suggest that direct contractile responses of the human detrusor muscle to muscarinic receptor stimulation in vitro are mediated solely via the M3‐muscarinic receptor subtype with no contribution from the major M2‐receptor population.
Biome reconstruction from pollen and plant macrofossil data for Africa and the Arabian peninsula at 0 and 6000 years
Authors: Jolly Dominique , Prentice I. Colin , Bonnefille Raymonde , Ballouche Aziz , Bengo Martin , Brenac Patrice , Buchet Guillaume , Burney David , Cazet Jean‐Pierre , Cheddadi Rachid , Edorh Therese , Elenga Hilaire , Elmoutaki Saida , Guiot Joel , Laarif Fouzia , Lamb Henry , Lezine Anne‐Marie , Maley Jean , Mbenza Muaka , Peyron Odile , Reille Maurice , Reynaud‐Farrera Isabelle , Riollet Guy , Ritchie Jim C. , Roche Emile , Scott Louis , Ssemmanda Immaculate , Straka Herbert , Umer Mohammed , Van Campo Elise , Vilimumbalo Sikiminywa , Vincens Annie , Waller Martyn
Published: March 2003

Biome reconstruction from pollen and plant macrofossil data provides an objective method to reconstruct past vegetation. Biomes for Africa and the Arabian peninsula have been mapped for 6000 yearsbpand provide a new standard for the evaluation of simulated palaeovegetation distributions. A test using modern pollen data shows the robustness of the biomization method, which is able to predict the major vegetation types with a high confidence level. The application of the procedure to the 6000 years data set (pollen and plant macrofossil analyses) shows systematic differences from the present that are consistent with the numerous previous regional and continental interpretations, while providing a more extensive and more objective basis for such interpretations. Madagascar, eastern, southern and central Africa show only minor changes in terms of biomes, compared to present. Major changes in biome distributions occur north of 15°N, with steppe in many low‐elevation sites that are now desert, and temperate xerophytic woods/scrub and warm mixed forest in the Saharan mountains. These shifts in biome distributions imply significant changes in climate, especially precipitation, between 6000 years and present, reflecting a change in monsoon extent combined with a southward expansion of Mediterranean influence.
The origin of present forest composition and pattern in southern Sweden
Authors: Lindbladh Matts , Bradshaw Richard
Published: March 2003

Abstract. Deciduous forests in much of southern Sweden are often located on former ‘in‐field’ sites close to farms and villages. The more distant ‘out‐field’ sites are almost always dominated by conifers. Using palaeecological methods, we investigate the origin of this forest pattern at a small estate in Småland, southern Sweden that was the birthplace of Carl Linnaeus.

Prior to extensive permanent settlement (c.ad 1100) both in‐fields and out‐fields supported a rich, mixed deciduous forest that was irregularly ravaged by forest fire. After ad 1100 the in‐field site was transformed into a species‐rich forest‐meadow system with tree composition similar to the pre‐cultural state with the addition of Fagus sylvatica L. The out‐field sites were used for grazing and slash‐and‐burn agriculture, but nevertheless maintained a high degree of forest continuity. Forest composition however changed from deciduous to coniferous dominance. Floristic diversity is closely linked to human activity. Herbaceous diversity is greatest during the earliest phase of the forest‐meadow system. It declines during the late‐mediaeval agrarian crisis and again during the over‐exploitation of the late nineteenth century. Diversity returns to pre‐cultural levels after the abandonment of the forest‐meadow system during the present century. Present forest composition and pattern in the study area are closely related to former human activities and are not primarily a function of soil type or present‐day management.
A 37,500‐year pollen record from Lake Malaŵi and implications for the biogeography of afromontane forests
Authors: DeBusk George H.
Published: March 2003

Abstract. Two 10‐metre cores were analysed and a 37,500 year pollen stratigraphy was established for Lake Malaŵi. A lowstand from 37,500 to 35,900 BP indicates extremely dry conditions. From 35,900 to 34,000 BP montane forests were widespread indicating cold, moist climate. Between 34,000 and 26,400 BP warm and dry conditions prevailed and forest area decreased. During the Last Glacial Maximum montane forest was widespread in the catchment, although woodlands apparently persisted at low altitudes: the expansion of the montane forest indicates that the aridity that affected equatorial Africa during this time period did not affect the Lake Malaŵi Catchment. The cold and relatively moist conditions during the Late Pleistocene probably allowed biotic interchange between the highlands of East and West Africa via the highlands along the Zaire—Zambezi watershed and among now‐isolated islands of Afromontane vegetation in the Lake Malaŵi catchment. The Holocene is characterized by climate and vegetation quite similar to today, with indications of slightly wetter conditions between 6150 and 3000 bp and slightly drier conditions between 8000 and 6150 bp. The low percentages of montane forest pollen throughout the Holocene support the hypothesis that the montane grasslands of Malaŵi are not recently anthropogenic.
Pre‐mission invasion of Erodium cicutarium in California
Authors: Mensing Scott , Byrne Roger
Published: March 2003

Abstract. The California grassland is dominated by alien plant species. It is generally assumed that the invasion of aliens began with the initial introduction of livestock by Spanish missionaries in 1769. In this paper we present pollen evidence which indicates that Erodium cicutarium, a Mediterranean annual, was well established in the Santa Barbara region several years before the founding of the first California mission at San Diego in 1769. Historical evidence shows that it took the Spanish nearly a decade to develop a livestock base in California. Disturbance by livestock was therefore not a necessary prerequisite for invasion by alien plants. Historical and macrofossil evidence indicates that E. cicutarium invaded California from Baja California.
Integrated palaeoecological evidence for biodiversity at the floodplain‐forest margin
Authors: Brayshay Barbara A. , Dinnin Mark
Published: March 2003

This paper presents the results of a combined palynological and palaeoentomological investigation into the changing diversity of Holocene floodplain forest biota at Bole Ings in the lower reaches of the River Trent. The aim in combining the two techniques represents an attempt to overcome some of the inherent differences of scale and resolution which characterize different types of fossil species data. The two lines of ecofactual evidence, pollen and beetle remains indicate changes in the biodiversity of the floodplain, both in terms of the diversity and abundance of individual species, habitats and ecosystem structure. The results of the study demonstrate the potential of this approach in tracing the decline in plant and entomofaunal diversity at the floodplain forest margin. Although there are recognized limitations imposed by taphonomic uncertainties, taxonomic resolution and restricted ecological data, the combined results provide added details of variations in both species composition and structural diversity within the landscape. The results emphasize the need for multidisciplinary research design in palaeoecological investigations of biodiversity.
Surface pollen‐vegetation relationships on the Atlantic seaboard: South Uist, Scotland
Authors: Brayshay Barbara A. , Gilbertson David D. , Kent* Martin , Edwards Kevin J. , Wathern Peter , Weaver Ruth E.
Published: March 2003

Studies of modern pollen rain from remote islands have raised a number of interesting issues concerning the spatial precision of present‐day pollen spectra in relation to their parent plant community types. This paper examines the relationships and degree of correlation between a sequence of contemporary vegetation types, environments and their associated surface pollen spectra from a transect across the island of South Uist in the Outer Hebrides of Scotland. Paired data on both contemporary vegetation and associated surface pollen assemblages have been collected and analysed using methods of numerical classification and ordination. In general terms, the modern pollen rain on South Uist reflects the major changes in vegetation pattern and the major community types fairly closely. The major boundary between the alkaline machair sand dune communities and the various acidic upland vegetation types is particularly clear. However, both variability in the vegetation and the effects of the strong prevailing westerly and south‐westerly winds tend to blur the boundaries of the various communities within each of these larger categories. On average 86.6% of the palynomorphs come from in‐community quadrat sources, while only 1.3% are from off‐island sources. The limited present‐day tree distribution on the transect is discussed in the context of the more widespread distribution of arboreal pollen. Overall, there is a strong numerical correspondence between vegetation, pollen and environmental variables. The various problems inherent in examining surface pollen spectra are reviewed.
Isozyme variation and recent biogeographical history of the long‐lived conifer Fitzroya cupressoides
Authors: Premoli A. C. , Kitzberger T. , Veblen T. T.
Published: March 2003

Aim Palaeoenvironmental records of Pleistocene glaciation and associated vegetation changes in Patagonia have led to the hypothesis that during the last glacial maximum (LGM) tree species survived locally in favourable habitats. If present populations originated from spread from only one refugium, such as an ice‐free area of coastal Chile (Single Refugium hypothesis), we would expect that eastern populations would be genetically depauperate and highly similar to western populations. In contrast, if the ice cap was not complete and tree species persisted in forest patches on both slopes of the Andes (Multiple Refugia hypothesis), we would expect a greater degree of genetic divergence between populations either on opposite sides of the Cordillera (Cordillera Effect scenario) or towards its present‐day southern distributional limit where the ice sheet reached its maximum coverage (Extent‐of‐the‐Ice scenario).

Location We tested this refugia hypothesis using patterns of isozyme variation in populations sampled over the entire modern range of the endemic conifer Fitzroya cupressoides (Mol.) Johnst. (Cupressaceae) in temperate South America.

Methods Fresh foliage was collected from twenty‐four populations and analysed by horizontal electrophoresis on starch gels.

Results Twenty‐one putative loci were reliably scored and 52% were polymorphic in at least one population. Populations from the eastern slope of the Andes were genetically more variable than those from the western slope; the former had a greater mean number of alleles per locus, a larger total number of alleles and rare alleles, and higher polymorphism. Genetic identities within western populations were greater than within eastern populations. Discriminant analyses using allelic frequencies of different grouping schedules of populations were non significant when testing for the Single Refugium hypothesis whereas significant results were obtained for the Multiple Refugia hypothesis.

Main conclusions Our results indicate that present Fitzroya populations are the result of spreading from at least two, but possibly more, glacial refugia located in Coastal Chile and on the southern flanks of the Andes in Argentina.
Using habitat models to map diversity: pan‐African species richness of ticks (Acari: Ixodida)
Authors: Cumming Graeme S.
Published: March 2003

Aims To show how logistic regression models for individual species can be used to produce improved estimates of species richness at a continental scale; to present these data for African ticks (Acari: Ixodida); and to address the question of whether there is a latitudinal gradient in tick species richness.

Location Africa.

Methods A database of 34,060 collection records for African ticks is used to produce a pan‐African map of known tick species richness at 0.25 × 0.25‐degree resolution. The likely distributions of seventy‐three species are then estimated from environmental factors using logistic regression, and localities where there is a suitably high probability of occurrence for a given species are added to the original data for that species. These augmented data are combined to produce a map of the predicted pan‐African distribution of tick species richness. The relationship of species richness to latitude is considered along a transect placed across some of the more extensively collected areas.

Results Maps of known and predicted pan‐African tick species richness are presented, and deficiencies in the available data are highlighted. Correlations using both known and predicted estimates of tick species richness suggest that ticks follow similar species richness patterns to those described for African mammals and birds, with a latitudinal gradient and highest species richness in east equatorial Africa. Tick species ranges are log‐normally distributed.

Main conclusions Carefully constructed probability surfaces offer a more powerful approach to mapping species ranges than simple presence‐absence maps. Such models are a useful extension to current biogeographical methods and have a wide range of potential applications in ecology, epidemiology and conservation. Tick species richness at a continental scale follows similar trends to those reported for mammals and birds.
A bioclimatic model for the distribution of Sphagnum‐dominated peatlands in North America under present climatic conditions
Authors: Gignac L. D. , Halsey L. A. , Vitt D. H.
Published: March 2003

Aim

A model was developed that estimates the climatic and geographical distribution of Sphagnum‐dominated peatlands in western Canada and North America.

Location

The model is based on the abundance of Sphagnum species on 640 peatland sites located in proximity to permanent weather stations throughout western Canada.

Methods

The per cent cover of Sphagnum species was quantified for all possible combinations of mean annual temperature (MAT) and mean annual total precipitation (MATP) found in western Canada. Abundance values were expanded to include all climatic values in North America, by interpolating within the matrix of values for western Canada using distance‐weighted means. Because Sphagnum‐dominated peatlands do not occur in areas having summer moisture index (P–PET) values ≤ 6 cm, that value was also included in the model. The result produced a matrix of 3360 grid nodes in which each node was characterized by MAT, MATP and P–PET values and the presence of Sphagnum‐dominated peatlands. The climatic data in the model was then match merged with the MAT, MATP and P–PET values obtained from Leemans & Cramer (The IIASA Database for Mean Monthly Values of Temperature, Precipitation, and Cloudiness on a Global Terrestrial Grid. International Institute for Systems Analysis, Laxenberg, 1991), which is a global data set that also contains geographical data on a 0.5° latitude by longitude grid. The geographical distribution of Sphagnum‐dominated peatlands was then mapped for western Canada and North America. Those maps were compared with the observed distribution of bogs and poor fens for the same area.

Results

Results of the comparisons indicated that the model's estimations matched the southern distribution of Sphagnum‐dominated peatlands relatively closely. Results for the northern distribution, however, were not as accurate. The overall accuracy was c. 80%.

Main conclusions

Some of the errors were caused by inaccurate climatic data which resulted from the lack of permanent weather stations in northern areas and the lack of definition of the northern limits of the actual distribution of bogs and poor fens. In areas where both the climatic data and the actual distribution of Sphagnum‐dominated peatlands are accurate, the model accuracy was c. 90%.
Ecological and biogeographical implications of Yellow‐Legged Gulls (Larus cachinnans Pallas) as seed dispersers of Rubia fruticosa Ait. (Rubiaceae) in the Canary Islands
Authors: Nogales Manuel , Medina Félix M. , Quilis Vicente , González‐Rodríguez Mercedes
Published: March 2003

Aim

Few data sets exist on the role of gulls as seed dispersal agents. Our purpose is to quantify the number of seeds dispersed, to assess damage to the seeds regurgitated and those expelled via cloaca, to check for possible differences in seed viability and germination rates, to study the seed retention time, and to evaluate gulls as adequate dispersal agents throughout the Canary Islands and for the colonization of this archipelago by this plant species (or its ancestor), from Africa.

Location

This study was developed in ‘Los Islotes’, a small archipelago located off the northern part of Lanzarote Island (Canaries).

Methods

We counted the number of seeds in each pellet and dropping collected and we measured and weighed them. Seed viability and germination from the three treatments (plants, pellets and droppings) were studied. Gut pass time (GPT) was assessed in two gulls by using glass beads (similar in size with Rubia fruticosa Ait. seeds). We employed a combination of univariate and bivariate statistical tests to analyse the data.

Results

From 81 pellets and 84 droppings, we extracted a total of 60,679 seeds (48,460 and 12,219, respectively). Data obtained in the GPT experiments show that a similar number of seeds are defecated and regurgitated. No externally damaged seed was observed and the majority were viable, giving more than 95% in all treatments (seeds from plants, droppings and pellets). Most seeds on these treatments showed germination rates of over 80%, verifying the importance of the gulls as legitimate dispersers of this Macaronesian endemic plant species. Taking into account that the gulls’ flight cruise speed is about 31–40 km h–1 and mean GPT of these birds is between 9.51 and 16.92 h, they could cover a distance between 295 and 677 km before expelling the seeds. This distance is well within the range of colonization of the different islands of the Canaries and the neighbouring archipelagos of Salvages and Madeira from the north‐west of Africa, where the ancestor of this plant may have originated.

Main conclusions

The results support the idea that gulls could have been one of the main agents responsible for the movement of R. fruticosa seeds among the islands of the Canaries and for the colonization of the Macaronesian archipelagos from Africa. Furthermore, this study suggests that gulls are generalist feeding seabirds with high capacity for seed transport and high long‐distance power displacements, could have played a more important role than that currently recognized by most authors, in the colonization of oceanic islands by some plants whose genetic origins were located at long‐distances.
Factors affecting the distribution of vascular plants, springtails, butterflies and birds on small tropical islands
Authors: Koh Lian Pin , Sodhi Navjot S. , Tan Hugh Tiang Wah , Peh Kelvin S.‐H.
Published: March 2003

Aim

The primary objective of our study was to examine the factors affecting the distribution of vascular plants, springtails, butterflies and birds on small tropical islands to understand how different groups of organisms with distinct biological traits respond to biogeographical variables, such as island area.

Location

The Republic of Singapore (103°50′E, 1°20′N) located at the southern tip of Peninsular Malaysia.

Methods

Seventeen islands were surveyed for vascular plants, springtails, butterflies and birds. Correlation analysis, simple linear and multiple regression analyses and the nestedness index were used to test the hypotheses that (1) area is the best predictor of species/genus richness at both the community and specific/generic levels; (2) there is no correlation between population density and island area; and (3) species/genera are distributed as nested subsets.

Results

Area was the most significant factor in determining the island distribution of springtails, butterflies and birds at both the community and specific/generic levels, although there were disparate responses to the biogeographical variables between the three taxonomic groups, as well as between common species within each group. Individual species displayed disparate responses to biogeographical variables, suggesting that patterns of distribution at the community level may not be a good indicator of the population dynamics of individual species/genera. Plant species richness did not show any correlation with any of the tested variables. Population densities of springtails, butterflies and birds were positively correlated with area, contradicting the assumption of the equilibrium theory of island biogeography that population density of island species is independent of area. Population densities of plants showed no correlation with any of the tested biogeographical variables. Vascular plant, springtail, butterfly and bird communities on the islands showed significant patterns of nestedness, indicating there may be species/genus‐specific responses to biogeographical variables.

Main conclusions

We conclude that although area was the most important factor affecting the island distribution of springtails, butterflies and birds, conservation planning must take into consideration how target taxonomic groups respond to biogeographical variables, instead of relying on general principles (e.g. those derived from the equilibrium theory). On a local scale, in order to preserve the island biodiversity of Singapore, the highest priority should be given to preserving the larger islands (e.g. Pulau Ubin) which not only have higher numbers of species, but also species that are absent on smaller islands.
Comparison of temperate and tropical rainforest tree species: growth responses to temperature
Authors: Cunningham S. , Read J.
Published: March 2003

Abstract Aim  To investigate whether the latitudinal distribution of rainforest trees in Australia can be explained by their growth responses to temperature.

Methods  The rainforest canopy trees Acmena smithii (Poir.) Merrill & Perry, Alstonia scholaris (L.) R. Br., Castanospermum australe Cunn. & C. Fraser ex Hook., Eucryphia lucida (Labill.) Baill., Heritiera trifoliolata (F. Muell.) Kosterm., Nothofagus cunninghamii (Hook.) Oerst., Sloanea woollsii F. Muell. and Tristaniopsis laurina (Sm.) Wilson & Waterhouse were selected to cover the latitudinal range of rainforests in eastern Australia. Seedlings of these species were grown under a range of day/night temperature regimes (14/6, 19/11, 22/14, 25/17, and 30/22 °C) in controlled‐environment cabinets. These seedlings were harvested after 16 weeks to determine differences in growth rate and biomass allocation among species and temperature regimes.

Results  The temperate species showed maximum growth at lower temperatures than the tropical species. However, there was considerable overlap in the growth rates of the temperate and tropical rainforest types across the temperature range used. Maximum growth of the tropical rainforest types was associated with changes in biomass allocation whereas the temperate rainforest types showed no significant changes in biomass allocation across the temperature range.

Main conclusions  All species showed temperatures for maximum growth that were considerably higher than those previously shown for maximum net photosynthesis. The growth responses to temperature of the rainforest species under these experimental conditions provided limited evidence for their restriction to certain latitudes. These growth responses to temperature showed that the physiological assumptions used in various types of vegetation‐climate models may not be true of Australian rainforest trees.
The diagnosis, transmission and prevention of HIV‐1 in the infant under 18 months of age: implications for nursing practice
Authors: Purssell Edward
Published: March 2003

• Vertical transmission of HIV from mother‐to‐child is a significant problem around the world. This paper examines the main issues that confront those caring for pregnant women who may transmit HIV‐1 to their babies with reference to the impact upon clinical practice.

• Nursing practice should accommodate research from a number of disciplines including medical and scientific researchers.

• A number of risk factors for vertical transmission have been identified, including immunological status of the mother, premature birth, method of delivery and breast feeding.

• The use of prophylactic zidovudine has also been shown to reduce the rate of transmission of the virus, although it is not clear at what point in pregnancy and delivery it exerts this protection.

• Although this paper considers recent advances in the prevention of vertical transmission, this is a rapidly developing area and readers are provided with Internet addresses where the most up to date information may be found.
A theoretical model of compliance in young diabetics
Authors: KYNGÄS HELVI
Published: March 2003

•The purpose of this paper is to present a theoretical model of compliance in young diabetics.

•According to the model, compliance is an active, intentional and responsible process in which young diabetics work to maintain their health in collaboration with the physician.

•Factors which improved compliance were motivation, the results of care, a sense of normality and adequate energy and will‐power for care.

•Motivation was improved by support and encouragement given by parents and was found to influence energy and will‐power for care.

•Energy and will‐power for care were increased through the support of parents, encouragement and the results of care. Furthermore it was found that when young diabetics were not afraid of complications, their energy and will‐power for care were better.

•Fear may, however, improve compliance, which is connected with the control of diabetes.

•The results of the study can be used to plan and implement care in young diabetics. In addition to this, the model is a good starting‐point for further development and for developing an instrument to measure compliance and the factors related to it.