bluuebunny/crossref_metadata_2025 huggingface dataset:
Breeding bird species diversity in the Negev: effects of scrub fragmentation by planted forests
Authors: Shochat Eyal , Abramsky Zvika , Pinshow Berry
Published: March 2003

Afforestation of the Northern Negev, Israel, from 1956 resulted in patches of primarily coniferous trees that fragmented large scrubland areas. This alteration in landscape pattern was followed by immigration of mediterranean bird species to the Negev.

We counted breeding birds, and measured various environmental variables in scrubland and planted forest patches, to test whether bird assemblages were random subsets of the regional species pool, and whether area or habitat structure was the major correlate with species abundance and distribution.

Of 22 bird species recorded, only three appeared in both scrub and forest, showing that these two habitats were occupied by different species assemblages. In both habitats, species richness increased with area at a rate greater than that expected by random sampling. In the scrub this increase was related to area per se, while in the forest it was related to habitat diversity in terms of stand age and tree type.

The density of forest species was unaffected by area, but specialist scrubland species declined as area decreased. We suggest that edge effects might reduce species abundance in small scrubland patches.

Nested subset analysis indicated that, at the community level, species composition was not random. However, at the species level, the distribution of three forest‐dwelling species appeared as random, as it was associated with habitat rather than with patch size.

Our results indicate that increased diversity of breeding birds in the Northern Negev will require scrub patches larger than 50 ha among the increasingly forested landscape. In contrast, increasing forest area would hardly increase species diversity in the whole landscape. Future forest management regimes should also aim to increase habitat diversity by adding foliage layers, especially in the understorey. Exotic coniferous forests support fewer species than deciduous forests in mediterranean zones around the world. The suggested management regime may improve such forests as habitat for species‐rich bird communities.
The effects of induced sterility on the territorial behaviour and survival of foxes
Authors: Saunders Glen , McIlroy John , Berghout Mani , Kay Barry , Gifford Eddie , Perry Rob , Van De Ven Remy
Published: March 2003

This paper reports on the behavioural effects of surgical sterilization when used to simulate immunocontraception in free‐ranging female foxes Vulpes vulpes.

During 3 years of trapping, 348 male and female foxes were fitted with transmitters in two treatment (females sterilized) and two untreated areas.

Radio‐tracking indicated that sterile and fertile vixens maintained similar‐sized territories during the breeding season, but that sterile females were possibly more likely to share their territories with each other.

There were no consistent differences in survival or dispersal between sterile and fertile females.

Outcomes from the study suggest that immunocontraception in free‐living foxes is feasible.
Estimating food consumption of marine predators: Antarctic fur seals and macaroni penguins
Authors: Boyd I.L.
Published: March 2003

Estimating food consumption is central to defining the ecological role of marine predators. This study developed an algorithm for synthesizing information about physiology, metabolism, growth, diet, life history and the activity budgets of marine predators to estimate population energy requirements and food consumption.

Two species of marine predators (Antarctic fur seal Arctocephalus gazella and macaroni penguin Eudyptes chrsolophus) that feed on krill in the Southern Ocean were used as examples to test the algorithm. A sensitivity analysis showed that estimates of prey consumed were most sensitive to uncertainty in some demographic variables, particularly the annual survival rate and total offspring production. Uncertainty in the measurement of metabolic rate led to a positive bias in the mean amount of food consumed. Uncertainty in most other variables had little influence on the estimated food consumed.

Assuming a diet mainly of krill Euphausia superba, annual food consumption by Antarctic fur seals and macaroni penguins at the island of South Georgia was 3·84 [coefficient of variation (CV) = 0·11] and 8·08 (CV = 0·23) million tonnes, respectively. This was equivalent to a total annual carbon consumption of 0·35 (CV = 0·11) and 0·72 (CV = 0·23) G tonnes year−1. Carbon expired as CO2 was 0·26 (CV = 0·06) and 0·65 (CV = 0·19) G tonnes year−1 for fur seals and macaroni penguins, respectively. The per capita food consumption varied depending upon sex and age but, overall, this was 1·7 (CV = 0·22) tonnes year−1 for Antarctic fur seals and 0·45 (CV = 0·22) tonnes year−1 for macaroni penguins.

The algorithm showed that the seasonal demand for food peaked in both species in the second half of the breeding season and, for macaroni penguins, there was a second peak immediately after moult. Minimum food demand occurred in both species during the first half of the breeding season.

As both Antarctic fur seals and macaroni penguins compete for krill with a commercial fishery, these results provide an insight into the seasons and stages of the life cycle in which competition is likely to be greatest.
A test of methods for estimating population size of the invasive land snail Achatina fulica in dense vegetation
Authors: Craze Paul G. , Mauremootoo John R.
Published: March 2003

Physical inaccessibility often complicates censuses of poorly mobile organisms. We therefore assessed the effectiveness of using a sample of quadrat counts to generate a population estimate corrected for inaccessible areas. The result is directly applicable to management of the introduced snail Achatina fulica on Ile aux Aigrettes, a small island off Mauritius, but also has implications for counting this and similar species elsewhere. Accurate counting of A. fulica is important given that this species is such a widespread and serious pest.

Counts were made in 17 quadrats taken from a grid covering the island. These were used to produce one population estimate by interpolating for the rest of the grid using GIS software (method 1). A second estimate assumed equal density of snails in accessible and inaccessible parts of the 17 quadrats, again with the population estimate interpolated (method 2).

Four further quadrats were cleared of vegetation and, by comparison of counts before and after clearance, the relationship between initial count and true snail number was estimated. This resulted in two further population estimates, with the relationship used to adjust counts in the 17 experimental quadrats before interpolation (methods 3 and 4).

All four estimates were tested using 35 additional quadrats of two types. Type 1 quadrats were physically cleared of vegetation; type 2 quadrats were fully accessible without clearance. Predicted counts in these quadrats were assessed for accuracy by comparison with actual counts.

The method 1 estimate was clearly inadequate; method 4 gave a consistent overestimate; method 2 gave the smallest error in both quadrat types. In type 1 quadrats, method 2 and 3 estimates were not significantly different and method 2 had a slight tendency to underestimate. Overall, for studies of A. fulica, method 2 is recommended. However, it should be noted that the study took place towards the end of the wet season. In the dry season, damp refuges under inaccessible vegetation may be more important and methods 3 and 4 may then give a better estimate.

The population of A. fulica with shell length > 10 mm on Ile aux Aigrettes near the end of the wet season in 2000 was between 37 300 and 45 100, with 39 700 being the best estimate.

The results underline the importance of considering inaccessible areas when accurate counts of species are needed, and a method is suggested by which a simple census technique can be adjusted. In the case of A. fulica, more accurate estimates of population size and distribution are invaluable in the management, monitoring and eradication of this invasive species.
Clustering of Saccharomyces boulardii strains within the species S. cerevisiae using molecular typing techniques
Authors: Mitterdorfer G. , Mayer H.K. , Kneifel W. , Viernstein H.
Published: March 2003

Aims: This study was undertaken to characterize and differentiate therapeutically relevant Saccharomyces yeasts. Among the isolates were so-called Saccharomyces boulardii strains, which are considered as probiotic agents, but whose taxonomic assignment is controversial. Moreover, the discriminative power of the applied molecular typing techniques should be evaluated.

Methods and Results: Genotyping was performed using species-specific polymerase chain reaction (PCR), randomly amplified polymorphic DNA-PCR, restriction fragment length polymorphism analysis of rDNA spacer regions and pulsed-field gel electrophoresis. Species-specific PCR assigned all of the product isolates to the species S. cerevisiae. By combining the other techniques, all isolates could be discriminated. Moreover, it could be demonstrated that probiotic S. boulardii strains form a separate cluster located within the species.

Conclusions: With the exception of species-specific PCR, all of the applied methodologies were suitable for subspecies typing and indicated a close relationship between the probiotic strains.

Significance and Impact of the Study: The methods applied in this study are considered powerful tools for quality control of therapeutically relevant yeasts. It is of crucial importance, especially regarding S. boulardii yeasts, to verify the identity of the correct strain, since the beneficial properties are considered to be strain-specific.
Saccharomyces cerevisiae wine yeast populations in a cold region in Argentinean Patagonia. A study at different fermentation scales
Authors: Lopes C.A. , Van Broock M. , Querol A. , Caballero A.C.
Published: March 2003

Aims: To study the diversity and dynamics of indigenous Saccharomyces wine populations during Malbec spontaneous fermentation, a representative Patagonian red wine, at both industrial and laboratory scale. Methods and Results: Two molecular techniques, including restriction fragment length polymorphism of mitochondrial (mt) DNA and polymorphism of amplified δ interspersed element sequences, were used for characterization of indigenous yeasts at strain level. The mtDNA restriction patterns showed the major discriminative power; however, by combining the two molecular approaches it was possible to distinguish a larger number of strains and, therefore, draw more representative conclusions about yeast diversity. Although a great diversity of wild Saccharomyces cerevisiae strains was observed, only nine represented more than half of the total Saccharomyces yeast biota analysed; five of these were common and took over the Malbec must fermentation in both vinifications. Conclusions: Many different indigenous S. cerevisiae strains were identified; nevertheless, the dominant strains in both industrial and laboratory vinification processes were just a few and the same. Significance and Impact of the Study: Small-scale fermentation appears to be a valuable tool in winemaking, one especially helpful in evaluating microbiological aspects of as well as possible interactions between inoculated selected strains and native strains.
Effect of spermine and α‐difluoromethylornithine on KCl‐ and CaCl2‐induced contraction in rat uterine smooth muscle
Authors: Revuelta M. P. , Cantabrana B. , Sánchez M. , Hidalgo A.
Published: March 2003

1 The effect of a polyamine, spermine (0.3–30 mm), and an ornithine decarboxylase inhibitor, α‐difluoromethylornithine (DFMO; 1–10 mm), given alone and in combination were studied on KCl (33, 60 or 90 mm)‐induced tonic contraction and on the cumulative concentration–response curves elicited by CaCl2 (30 μm to 10 mm) in a depolarizing (with 33, 60 or 90 mm of KCl) calcium‐free medium in isolated rat uterus.

2 Spermine elicited a concentration‐dependent relaxation on KCl 33 mm (IC50 = 2.18 ± 0.37 mm, n = 6), 60 mm (IC50 = 7.80 ± 0.79 mm, n = 11) and 90 mm KCl (IC50 = 29.55 ± 4.08 mm, n = 7) induced tonic contraction. The IC50 values were significantly different (P < 0.01).

3 DFMO relaxed the tonic contraction induced by 33 mm of KCl (Emax = 80.70 ± 13.01%) but only relaxed the contractions induced by 60 and 90 mm of KCl to 23.60 ± 4.60% and 16.90 ± 4.10%, respectively. DFMO (10 mm) did not modify the concentration‐dependent relaxation elicited by spermine on KCl (60 mm)‐induced tonic contraction.

4 KCl (33, 60 or 90 mm) did not produce contraction in a calcium‐free medium, but enabled CaCl2 (30 μm to 10 mm) to induce cumulative concentration‐dependent contraction of the rat uterus. The EC50 values for CaCl2 were: 0.74 ± 0.08 (n = 12), 0.34 ± 0.03 (n = 14) and 0.48 ± 0.02 (n = 12) mm in medium with 33, 60 or 90 mm of KCl, respectively.

5 Spermine (1 mm) and DFMO (1 mm) did not modify the concentration–response curves induced by CaCl2 in medium with 33 mm of KCl. Higher concentrations of spermine (3 mm) and DFMO (10 mm) strongly reduced the contractile effect of CaCl2 to 35.69 ± 3.96% (n = 6) and 40.14 ± 10.74% (n = 6). This inhibitory effect of spermine and DFMO was prevented by increasing KCl concentration in the medium to 60 or 90 mm. Thus, the Emax of CaCl2 in the presence of spermine (3 mm) was 66.26 ± 6.96% and 89.02 ± 2.89% in a 60 and 90 mm KCl medium, respectively. In the presence of DFMO (10 mm) the Emax of CaCl2 reached 100% when KCl was increased.

6 Spermine (1 mm) plus DFMO (1 mm) and spermine (1 mm) plus DFMO (10 mm) produced a synergic inhibitory effect of CaCl2‐induced contraction in medium with 33 mm of KCl. Spermine (3 mm) plus DFMO (10 mm) produced a total inhibition of CaCl2‐induced contraction.

7 The inhibitory effect of spermine (1 mm) plus DFMO (10 mm) was also prevented by increasing KCl concentration in the medium to 60 or 90 mm. The Emax for CaCl2 (10.9 ± 5.5%) in the presence of KCl 33 mm increased up to 93.2 ± 2.1% and 96.3 ± 1.2% when the KCl concentration in the medium was enhanced to 60 or 90 mm.

8 Our results suggest that a calcium inhibitory effect of spermine and DFMO in isolated rat uterus could be produced, since this was prevented by depolarization, as a result of the increase of KCl concentration in the medium.
Effect of calcium antagonists on the response to noradrenaline in the whole and bisected rat vas deferens
Authors: Boselli C. , Bianchi L. , Barbieri & A. , Grana E.
Published: March 2003

1 The present study was carried out to look at the effect of different calcium antagonists on the response to noradrenaline in the whole and bisected rat vas deferens considering that the response consisted of three components (I) the phasic response (II) the tonic response and (III) the spikes (rhythmic contractions).

2 Nifedipine (3 × 10−−9–1 × 10−−7 m) inhibited all the components at the same concentration range, verapamil (1 × 10−−7–1 × 10−−5 m) inhibited the phasic and tonic response but not the rhythmic activity. This latter component, at a certain concentration range and especially in the prostatic portion was markedly potentiated. Diltiazem and flunarizine lay in an intermediate position.

3 Papaverine, a Ca2+ antagonist that acts mainly intracellularly, inhibited preferentially the tonic component; ryanodine was practically inactive.

4 Cromakalim inhibited only partially the phasic and tonic components but totally inhibited the rhythmic contractions.

5 These results can be explained by postulating two types of calcium channels opened by α‐adrenoceptor stimulation. The first one is verapamil‐ and nifedipine‐sensitive and allows the entry of Ca2+ directly available for the contraction and responsible for the phasic and partially responsible for the tonic component. The second channel is merely nifedipine‐sensitive and allows the entry of Ca2+ trigger which can release Ca2+ from intracellular sites: the mobilized Ca2+ is able to sustain the tonic component and is the main one responsible for the rhythmic activity. There is the possibility that this second channel is associated with ATP‐sensitive K+ channels.
In vivo demonstration of α‐adrenoceptor‐mediated positive inotropy in pithed rats: evidence that noradrenaline does not stimulate myocardial α‐adrenoceptors
Authors: Broadley K. J. , Williamson K. L. , Roach A. G.
Published: March 2003

1 This study examines whether positive inotropy via α‐adrenoceptors could be observed in vivo in pithed rats. Cardiac contractility was measured as the maximum rate of rise of left ventricular pressure (dP/dtmax). Heart rate and aortic blood pressure were also recorded.

2 The selective α1‐adrenoceptor agonists, methoxamine, cirazoline, amidephrine and phenylephrine caused dose‐related increases in dP/dtmax. This response was progressively reduced by increasing doses of the α1‐adrenoceptor antagonist prazosin. However, since the concomitant increase in diastolic blood pressure (DBP) was also blocked, the changes in dP/dtmax may have been a consequence of increased after load.

3 Adrenaline and noradrenaline also increased dP/dtmax, accompanied by pressor responses. Propranolol (1 mg kg−−1) antagonized the increase in dP/dtmax in response to noradrenaline, suggesting β‐adrenoceptor involvement, but not that to adrenaline. The additional presence of prazosin (1 mg kg−−1) further shifted the dose–response curves for both noradrenaline and adrenaline to the right.

4 Analysis of the increases in dP/dtmax at predetermined increases in DBP by each agonist revealed three groups of regression lines. Adrenaline in the presence of propranolol and the four selective α1‐adrenoceptor agonists occupied a common central position. Above this group were adrenaline and noradrenaline in the absence of antagonists; their additional effects on contractility were β‐adrenoceptor‐mediated since the regression lines were lowered by propranolol. Clearly below the main group of agonists was noradrenaline in the presence of propranolol.

5 Thus, for a given increase in DBP, adrenaline (in the presence of β‐blockade) and the α1‐adrenoceptor agonists exert an additional inotropic effect to noradrenaline (also in the presence of β‐blockade). This is concluded to be an α‐adrenoceptor‐mediated increase in cardiac contractility which is not shared by noradrenaline.
Modelling the changes due to the endothelium and hypertension in the α‐adenoreceptor‐mediated responses of rat aorta
Authors: Tabernero A. , Giraldo J. , Vila E.
Published: March 2003

1 The present study focuses on the role of endothelium on α1‐adrenoceptor‐mediated vasoconstriction in aorta from Wistar Kyoto (WKY) and spontaneously hypertensive rats (SHR). To define and quantify changes in the parameters governing agonism at α1‐adrenoceptor by hypertension and/or endothelium, the operational model of analysis was used.

2 In either endothelium intact or denuded aorta, the sensitivity (P < 0.001) and the maximum contraction (P < 0.05) to phenylephrine were smaller in SHR than in WKY.

3 However, in each strain of rats, removal of endothelium increased the sensitivity (P < 0.001) to phenylephrine but reduced (P < 0.05) KCl‐evoked vasoconstriction, suggesting a modulation of these responses by the endothelium. The observed differences in sensitivity and maximum contraction are interpreted in terms of the operational parameters: Em, the maximum possible effect; pKA, the agonist affinity; α, the agonist efficacy and n, the slope for the function relating receptor occupancy to pharmacological effect. The estimated parameters reflected differences, between strains, in the signal transduction processes linked to α1‐adrenoceptor stimulation ascribed to the presence of the endothelium.

4 NG‐nitro‐
l‐arginine methyl ester (L‐NAME), enhanced to a similar extend in both rat strains the sensitivity (P < 0.001) and the maximum contraction to phenylephrine. Indomethacin reduced the maximum contraction to phenylephrine by 56.85% in SHR and by 11.80% in WKY suggesting that contracting prostanoids play a more major role in this response in SHR than in WKY. Nevertheless, these inhibitors were without effect on denuded vessels from both strains suggesting that NO and cyclooxygenase products from the media or the adventitia do not play a role on the phenylephrine‐mediated responses.

5 The studied endothelial factors partially explain the observed differences in modulation of α1‐adrenoceptor responses by the endothelium but suggest the participation of other compounds released by the endothelium.
In situ hybridization and immunocytochemistry of α1‐adrenoceptors in human peripheral blood lymphocytes
Authors: Tayebati S. K. , Bronzetti E. , Morra di Cella S. , Mulatero P. , Ricci A. , Rossodivita I. , Schena M. , Schiavone D. , Veglio F. , Amenta F.
Published: March 2003

1 α1‐Adrenoceptor subtypes were investigated in cytospin centrifuged preparations of human peripheral blood lymphocytes by in situ hybridization and immunocytochemistry.

2 In situ hybridization cytochemistry revealed α1A‐, α1B‐, and α1D‐receptor mRNA in human peripheral blood lymphocytes. Lymphocytes hybridized for α1A receptor subtype represented approximately 30% of total lymphocytes, those hybridized for α1Β‐ and α1D‐receptor subtypes averaged 42 and 25% of total lymphocytes, respectively.

3 Cytospin centrifuged lymphocytes exposed to anti‐α1A‐, α1Β‐ or α1D‐receptor protein antibodies, developed specific immunostaining. Approximately 27% of total lymphocytes were immunoreactive for α1A‐receptor protein, 40% displayed α1B‐receptor protein immunoreactivity and 22% α1D‐receptor protein immunoreactivity. Analysis of percentages as well as of lymphocyte morphology of in situ hybridized and immunolabelled lymphocytes suggests the co‐expression of mRNA receptor signal and protein receptor immunostaining in the same lymphocyte.

4 The demonstration of both α1‐adrenoceptor mRNA and receptor protein subtypes suggests that α1‐adrenoceptors may have a role in regulating lymphocyte function.

5 The possibility of demonstrating receptor protein immunoreactivity in a small amount of blood, such as that required for preparing cytospin‐centrifuged lymphocytes, may stimulate research to evaluate the role of these receptors in lymphocytes and to establish if assessment of lymphocyte α1‐adrenoceptors may represent a marker of their status in health and disease.
Adrenalectomy‐induced potentiation of morphine action in guinea‐pig ileum: possible decrease in the release of endogenous opioids from opioidergic neurones
Authors: Ozaki M. , Masuda Y. , Kishioka S. , Yamamoto H.
Published: March 2003

1 The effects of adrenalectomy on exogenous and endogenous opioid actions in guinea‐pig isolated myenteric plexus‐longitudinal muscle (MPLM) were investigated.

2 A decrease in serum cortisol level to about 37% of the level in the sham‐operated group was obtained in adrenalectomized animals (sham: 53.5 ± 7.2 μg 100 ml–1; adrenalectomized: 20.0 ± 3.6 μg 100 ml–1).

3 The concentration–response curve of twitch inhibition, which was induced by electrical field stimulation (0.1 Hz, 0.5 ms pulse width, maximum intensity), caused by a low concentration of morphine (5 × 10–9–5 × 10–7 M) was not affected, but at high concentration (10–6–10–5 M) there was an upward shift in the adrenalectomized group compared with the sham‐operated control, although the basal twitch contraction was not changed by adrenalectomy.

4 The twitch inhibition induced by a high concentration of morphine (10–6 M) in the adrenalectomized group was antagonized to the same level as that in sham‐operated controls by naloxone (NLX) (3 × 10–7 M).

5 Post‐tetanic twitch inhibition, an indicator of endogenous opioid release, induced by tetanic stimulation (10 Hz, 0.5 ms pulse width, maximum intensity, for 1 min) was inhibited in the adrenalectomized group compared with the sham‐operated controls. The antagonism of inhibition in both groups was equivalent to that exerted by NLX (10–7 M).

6 Acetylcholine‐evoked contraction of the muscle was not influenced by adrenalectomy.

7 These results suggested a possible mechanism for the increase in sensitivity of the opioid receptors to morphine by adrenalectomy, resulting from a decrease in the release of endogenous opioids from the opioidergic neurones in the ileum.
Vascular inhibitory actions of 17β‐oestradiol in rat portal vein
Authors: Leong S. , Docherty J. R.
Published: March 2003

1 We have examined the effects of 17β‐oestradiol on spontaneous spikes and contractions to noradrenaline in rat portal vein.

2 The 17β‐oestradiol (10 μM) significantly reduced the maximum height of spontaneous spike contractions and significantly reduced the maximum contraction to noradrenaline (10 μM) in portal vein from both male and female rats.

3 The protein synthesis inhibitor cycloheximide (10 μM) did not significantly affect the inhibitory actions of 17β‐oestradiol (10 μM) against spontaneous spike contractions and contractions to noradrenaline.

4 In summary, 17β‐oestradiol diminishes spontaneous spike contractions and the contractile response to noradrenaline in rat portal vein, by a non‐genomic action.
Adrenaline hypothesis: effect of formoterol on noradrenaline release
Authors: Maignan E. , Advenier C. , Safar M. , Cuche J.‐L.
Published: March 2003

1 Originally, the so‐called `adrenaline hypothesis' related the release of noradrenaline (NA) to stimulation of presynaptic β2‐receptors in nerve endings; now it confers a possible role to adrenaline taken up then released by nerves endings. It represents a potentially useful therapeutic pathway. The present study aims to investigate the effects of formoterol, a highly selective β2‐adrenoceptor agonist.

2 It was carried out in freely moving rats, the isotope dilution technique being used to measure the NA spill over rate (NA‐SOR) and metabolic clearance rate (MCR).

3 A series of three results are reported. (a) When compared with adrenaline on equimolar basis, formoterol (2.3 μg kg−1 min−1) increased NA‐SOR while mean arterial blood pressure was decreased and heart rate increased. Thus, it was difficult to separate a direct presynaptic effect from indirect baroreflex‐dependent activation of the sympathetic system. (b) When formoterol was infused at 1 ng kg−1 min−1, a dose empirically defined to induce no haemodynamic effect, NA‐SOR was significantly increased, while NA‐MCR remained unchanged. (c) The NA‐SOR response to formoterol was not amplified by the presynaptic α2‐adrenoceptor blocker, yohimbine, in contrast to the NA‐SOR response to adrenaline.

4 In conclusion, formoterol, a β2‐adrenoceptor agonist, is shown to increase the release and plasma concentration of NA while its clearance was not changed.
Bladder instability: a re‐appraisal of classical experimental approaches and development of new therapeutic strategies
Authors: Boselli C. , Govoni S. , Condino A. M. , D'Agostino G.
Published: March 2003

1 Despite the growing social interest in human urinary tract disorders, the aetiology of detrusor instability remains poorly understood. Myogenic and neural impairment of detrusor activity caused by CNS or autonomic injuries can results in dysfunctions of normal voiding of the bladder such as urinary incontinence.

2 The contractility of human detrusor smooth muscle is critically dependent on acetylcholine‐induced muscarinic receptor activation. Biochemical and functional in vivo and in vitro studies suggest the presence of an heterogeneous population of muscarinic receptor subtypes (M1–M4) localized at muscular and neutral sites. There is increasing evidence on the prejunctional auto‐ and hetero‐regulation of acetylcholine release from parasympathetic nerve endings in modulating detrusor muscle contraction during micturition.

3 Activation of P2X purinoreceptors closely associated with the parasympathetic varicosities seems to be implicated to varying extent in the contractility in normal or instable human detrusor. Interestingly, P2X1 subtype expression on smooth muscle increases considerably in the symptomatically obstructed bladder. A striking absence of P2X3 and P2X5 subtypes was observed in the cholinergic innervation of detrusor from patients with urgent incontinence. Thus, it is likely that alteration of the neural acetylcholine control can play a critical role in pathological states.

4 If the failures in storage and voiding can be recognized urodynamically, considerable difficulties remain in investigating the underlying functional changes especially because the study of the pathophysiology requires techniques that can be justified in animals but not in humans.

5 Recently, to solve this problem an alternative technique using human smooth muscle cells in culture has been developed. Human cell lines may be relevant in investigating the molecular pathways in physiological and pathological conditions.

6 The potential development of novel molecular therapeutic strategies such as gene therapy and tissue engineering is also discussed.
Fire history of an isolated subalpine mountain range of the Intermountain Region, United States
Authors: Murray Michael P. , Bunting Stephen C. , Morgan Penny
Published: March 2003

Fire has historically been an important ecological component of forests in the Intermountain Region of the northwestern United States. This study is set in a small biogeographically disjunct mountain range. Our research objectives were to (1) investigate the historical frequency, severity, size, and spatial pattern of fire; (2) determine if and how fire regimes have changed since Euro‐American settlement; and (3) compare how fire regimes of a small isolated range compare to nearby, but considerably larger, mountain agglomerations. Our findings suggest that this mountain range has historically supported fires typified by small size and high frequency, resulting in a high degree of spatial pattern complexity compared to mountain agglomerations. We also found disparity in size and burn severity solely within the study area based on the bisecting Continental Divide. Since the advent of Euro‐American settlement in the 1870s, fire frequency and sizes of individual fires in the West Big Hole Range have significantly decreased resulting in an estimated 87% reduction in area burned. We discuss potential relationships of mountain range isolation and fire regimes in the Intermountain Region. Furthermore, we suggest that the relative small size of this mountain range predisposes it to greater anthropogenic effects upon fire occurrence.
Phytogeographical and phenological comparison of the Meuse and the Saône valley meadows (France)
Authors: Grevilliot F , Broyer J , Muller S
Published: March 2003

The meadows of the floodplains of the Saône and the Meuse contain similar ecosystems subject to regular winter and spring flooding. The floristic and faunistic biodiversity decreases with the intensification of agricultural practices. The plant communities show the same zonation along a topographic gradient and have similar floristic progression. Thus, the climatic, biogeographic, human and soil factors have determined the floristic particularities of each valley. The floristic affinities of the two floodplains permitted the comparison of the phenological development of fourteen plant species. Many gaps in the development of species have been observed. These could be explained by the climatic differences betwen the two valleys (sub‐Mediterranean influences in the Saône and sub‐Atlantic in the Meuse), the existence of different types of soils in each valley (sand part more important in the Saône) and the occurrence of specific ecotypes in each valley.
The latitudinal gradient of species diversity among North American grasshoppers (Acrididae) within a single habitat: a test of the spatial heterogeneity hypothesis
Authors: Davidowitz Goggy , Rosenzweig Michael L.
Published: March 2003

Abstract. The spatial heterogeneity hypothesis predicts a positive relationship between habitat complexity and species diversity: the greater the heterogeneity of a habitat, the greater the number of species in that habitat. On a regional scale, this hypothesis has been proposed to explain the increases in species diversity from the poles to the tropics: the tropics are more diverse because they contain more habitats. On the local scale, the spatial heterogeneity hypothesis suggests that the tropics are more diverse because they contain more microhabitats. The positive relationship between habitat heterogeneity and species diversity, on the local scale, is well documented. In this paper, we test whether habitat heterogeneity on the local scale can explain the latitudinal gradient of species diversity on the regional scale. We determined the latitudinal gradient of species diversity of 305 species of North American grasshoppers using published distribution maps. We compared the slope of this multihabitat (regional‐scale) gradient with the slope of a within‐habitat (local‐scale) gradient in the prairie grasslands. Our results show no significant difference between the slopes at the two scales. We tested the generality of our results by comparing multi‐ and within‐habitat latitudinal gradients of species diversity for ants, scorpions and mammals using data from the literature. These results are in accordance with those from grasshoppers. We can therefore reject the local‐scale spatial heterogeneity hypothesis as a mechanism explaining the regional‐scale latitudinal gradient of species diversity. We discuss alternative mechanisms that produce this gradient.
Height growth rate tradeoffs determine northern and southern range limits for trees
Authors: Loehle Craig
Published: March 2003

Abstract. Identifying the biological determinants of range limits of trees is an unsolved problem of critical importance for predicting the effects of climate change on forests. Data showing that many boreal trees can grow in temperate climates indicate that southern range limits do not necessarily result from excessive temperature per se. A growth tradeoff could exist between freezing tolerance and height growth rate if adaptations to tolerate cold climates interfered with growth. Analysis of height growth rate versus freezing tolerance for twenty‐two North American trees provided evidence for such a tradeoff. Provenance trials of numerous tree species also showed that a tradeoff exists within species, indicating a genetic basis for these traits. The result of this tradeoff is that at their southern range margins most species do not suffer from too much heat but rather face competitors with a faster growth rate. The implication for future climate change is that forests will not suffer catastrophic dieback due to increased temperatures but will rather be replaced gradually by faster growing types, perhaps over hundreds of years.
On the generation of diversity in archipelagos: a re‐evaluation of the Quinn‐Harrison ‘saturation index’
Authors: Mac Nally R. , Lake P. S.
Published: March 2003

AimQuinn & Harrison (1988;Oecologia,75, 132)suggested that several small, isolated islands generally bore a higher diversity than fewer (or single) larger islands. They proposed a method by which the cumulative diversity of islands arranged small‐to‐large (‘STOL’) and large‐to‐small (‘LTOS’) could be used to identify how island area and species distributions interact to produce the system‐wide or ensemble diversity. From these curves, an ‘index of saturation’ (SI) was calculated to summarize the way in which diversity is generated on a given archipelago. Unfortunately, the method did not allow statistical judgements to be made. Our paper considers the reliability of the Quinn‐Harrison approach, especially in light of the inconsistency of its implications compared with ‘nestedness’ analyses.

LocationThree example data sets are used: reptiles from the archipelagos of the Sea of Cortéz, breeding land‐birds from the Canary Islands, and stream invertebrates occupying rocks in the Steavenson River of central Victoria, Australia.

MethodsWe refine the Quinn‐Harrison technique to produce a method by which the difference between the STOL and LTOS cumulative diversity curves can be gauged statistically (the ξ statistic). We also propose an alternative statistic (η)—which we believe to be more intuitive—that preferentially weights species occurring on few patches and that can be statistically assessed by using Monte Carlo simulation.

ResultsThe basic Quinn‐Harrison technique is not reliable for diagnosing whether systems are characterized by STOL or LTOS patterns. The three example data sets provide the range of options for faunal‐diversity generation (STOL overlies LTOS, LTOS overlies STOL, and coincident). However, statistical analyses indicate that the patterns all are generated by the rarer species occupying larger islands. The results of the revised ξ statistic and especially the η statistic are consistent with this deduction, which in turn relate well with faunal‐nestedness analyses.

Main conclusionsThere was a contradiction between the Quinn‐Harrison analyses, which suggested that most rarer taxa occurred in impoverished, smaller islands, and results of nestedness analyses, which indicated that the rarer taxa occurred on more speciose, larger islands. The resolution to this dilemma is that the Quinn‐Harrison diagram and saturation index are so flawed that they yield unreliable resultsvis a visthe generation of diversity on archipelagos.
Bergmann's rule in the ant lion Myrmeleon immaculatus DeGeer (Neuroptera: Myrmeleontidae): geographic variation in body size and heterozygosity
Authors: Arnett Amy E. , Gotelli Nicholas J.
Published: March 2003

Aim Geographic variation in body size and heterozygosity were surveyed for discrete populations of the ant lion, Myrmeleon immaculatus DeGeer, collected from the central and northeastern United States.

LocationCollection sites were located in the central and eastern United States ranging from western Oklahoma to northern New York.

Methods We collected 872 M. immaculatus larvae from thirty‐four collecting sites. At each site, we randomly sampled ant lion pits and collected between fifteen and fifty‐two larvae in total. Larvae were preserved in 95% ETOH for morphological analysis and frozen in a −80°C freezer for protein electrophoresis. We measured the body size of eighty‐five preserved adult M. immaculatus obtained from museum collections using head width as an indicator of body size. Five enzymes [GPI (glucose phosphate isomerase), MDH (malate dehydrogenase), PEP (peptidase), DIA (diaphorase) and SOD (superoxide dismutase)] were used in the heterozygosity analyses.

Results Larval and adult body size increased with latitude, but decreased with elevation. Average heterozygosity, measured at five polymorphic loci, also increased significantly with latitude. Minimum temperature variance was the best predictor of body size, whereas precipitation and maximum temperature were the best predictors of heterozygosity. Populations were genetically differentiated from one another and showed a pattern of isolation by distance, as measured by Wright's Fst values and Nei's genetic distances.

Main conclusions Sampling artifacts, heat conservation, character displacement, cell‐size variation, density‐dependent mortality, and differential dispersal probably cannot account for latitudinal variation in ant lion body size. Our results implicate the importance of diurnal photoperiod, which varies with latitude, but not with elevation. Because photoperiod often controls growth, diapause, and metamorphosis, it may be an important determinant of latitudinal clines in body size and life history of insects.
How to do BPA, really
Authors: Brooks Daniel R. , Van Veller Marco G. P. , McLennan Deborah A.
Published: March 2003

Aim

Recent comparisons of different approaches to historical biogeography have suffered in part because Brooks Parsimony Analysis (BPA) has been characterized as a one‐step process following protocols proposed in 1981. Subsequent modifications have resulted in a two‐step methodology. This contribution presents the mechanics and applications of those modifications.

Methods

The first step, or Primary BPA, which is similar to the original BPA but with modifications proposed by Wiley (1986, 1988a, b), is used to assess whether or not there is support for a single general area cladogram. The second step, Secondary BPA, proposed by Brooks (1990), depicts exceptions to the general area cladogram explicitly by duplicating areas having a reticulate history.

Results

The analytical basis of area duplication in secondary BPA is explained more fully than in previous accounts, and the manner in which secondary BPA explicitly depicts falsification of the null hypothesis of simple vicariance is presented for four general cases.

Main conclusions

BPA, as fully implemented, is capable of accounting for the complexity of speciation, dispersal and extinction events in a historical biogeographic context without removing or modifying input data from basic phylogenies, so long as at least three clades are analysed simultaneously to provide a distinction between general and special distribution elements.
Another look at the richness of helminth communities in tropical freshwater fish
Authors: Poulin Robert
Published: March 2003

Aim

Recently,Choudhury & Dick (2000)argued that helminth parasite communities in tropical freshwater fish are not richer than those in temperate fish. Here their data is re‐examined in an analysis that takes into account important confounding variables, and their conclusions are revisited.

Location

The data set covers fish species from many tropical areas and from the north temperate area of the nearctic zone.

Methods

Multivariate analyses are used to control the influence of sampling effort and host body size, two factors that may confound the comparison between tropical and temperate helminth communities. In addition, phylogenetically independent contrasts are derived from the fish taxa included in the data set and used to remove the potential effect of shared phylogenetic history on the richness of helminth communities.

Results

Both host body size and the number of hosts examined correlated positively with the number of species found in a helminth community, and fish body size also correlated with measures of richness corresponding to the mean number of helminth species per fish individual. After controlling for the effects of these two confounding variables, temperate helminth communities still had higher richness scores than those from the tropics. The analysis using independent contrasts removed the remaining potential confounding factor, i.e. host phylogeny, and it again showed that helminth communities of temperate fish taxa are richer than those of related fish taxa from the tropics. This last result, however, applies only to the number of helminth species found in a helminth community, and not to the mean number of helminth species per individual fish host.

Main conclusions

The general conclusion of the present study is similar to that ofChoudhury & Dick (2000). However, the new analysis has ruled out some confounding factors as potential explanations for the patterns, and has served as an indirect test of a version of the area hypothesis (i.e. helminth diversity is explained by host size). The reason why this latitudinal gradient in richness runs counter to those usually observed in other plant and animal assemblages remains to be found.
The frost resistance of ericoid heath plants in the British Isles in relation to their biogeography
Authors: Bannister P. , Polwart A.
Published: March 2003

Aim

To determine whether rare British ericoid heaths are restricted to the oceanic fringes of south‐western England and western Ireland because of their sensitivity to frost.

Location

The Wirral Peninsula, Cheshire, England. Shoots of the common heaths (Calluna vulgaris (L.) Hull, Erica tetralix L., Erica cinerea L.) were obtained from Thurstaston Heath and those of the rarer heaths (E. mackaiana Bab., E. ciliaris L., E. erigena R. Ross and E. vagans L.) from collections of known provenance in Ness Gardens.

Methods

Frost resistance of cut shoots was determined at approximately monthly intervals between February 1994 and March 1995. Shoots were exposed to a range of freezing temperatures and scored for damage. Freezing resistance was determined as the temperature that caused 50% damage to the shoots.

Results

The frost resistance of the common heaths was in accord with their geographical distribution. Calluna vulgaris and E. tetralix extend furthest north and east in Europe and developed the greatest frost resistance in winter (< –20 °C). Erica cinerea is widespread throughout the British Isles with an oceanic south‐western distribution in Europe and was resistant to only –13 °C. Erica vagans has a similar frost resistance to E. cinerea but has a restricted distribution in the British Isles, whilst the other rare heaths are more frost resistant than either E. cinerea or E. vagans. The frost resistance of all species increased with shorter daylengths and decreased with higher temperatures, suggesting that global warming might result in increased sensitivity to frost in these species.

Main conclusions

Whilst the distributions of the common heath species are in accord with their frost resistance, those of the rarer heaths are not. Consequently, factors other than susceptibility to cold winters must account for the restriction of rare species of Erica to the southern and western fringes of Britain and Ireland.
A comparison of the tropical montane pteridophyte floras of Mount Kinabalu, Borneo, and Parque Nacional Carrasco, Bolivia
Authors: Kessler Michael , Parris Barbara S. , Kessler Elke
Published: March 2003

Aim

To compare the species richness, and taxonomic and life‐form composition of tropical montane pteridophyte floras on two well‐documented sites: Mount (Mt) Kinabalu, Sabah, Borneo and Parque Nacional (PN) Carrasco, central Bolivia.

Methods

Using published lists, we compared the elevational distribution of overall species richness, specific pteridophyte families, and of life‐forms along both study sites. Additionally, we compared point‐diversity by establishing 108 plots of 400 m2 at PN Carrasco, and 15 such plots at Mt Kinabalu and three at a lowland site at Danum Valley in south‐eastern Sabah, Borneo (200 m).

Results

The numbers of species, genera, and families recorded on Mt Kinabalu were 14–23% higher than at PN Carrasco, most probably as a result of more intensive long‐term collecting activity. Opposed to this, species richness per 400 m2 plot was somewhat higher at PN Carrasco, especially amongst epiphytes at mid‐elevations. Overall, there was a remarkable similarity in the elevational distribution of species numbers, of individual pteridophyte families, and of life‐forms. Major differences included a more pronounced peak of species richness at 1500 m on Mt Kinabalu, considerably higher species numbers of Elaphoglossum at PN Carrasco and of Grammitidaceae at Mt Kinabalu, and a higher proportion of debris‐trapping epiphytes and lithophytic species at Mt Kinabalu and of terrestrial herbs at PN Carrasco.

Main conclusions

The majority of present‐day species of the studied pteridophyte floras evolved largely independently from about 66–100 common ancestors. The striking convergence of the pteridophyte floras of both sites indicates that the taxonomic and morphological composition of the pteridophyte floras is subject to selective pressure, and that specific pteridophyte families are evolutionarily pre‐disposed to occupy specific ecological niches.
The species–area relationship does not have an asymptote!
Authors: Williamson Mark , Gaston Kevin J. , Lonsdale W. M.
Published: March 2003

Aim

To attack a widespread myth.

Location

World‐wide.

Methods

Simple mathematical logical and empirical examples.

Results

As both species and area are finite and non‐negative, the species–area relationship is limited at both ends. The log species–log area relationship is normally effectively linear on scales from about 1 ha to 107 km2. There are no asymptotes. At the intercontinental scale it may get steeper; at small scales it may in different cases get steeper or shallower or maintain its slope.

Main conclusion

The species–area relationship does not have an asymptote.