bluuebunny/crossref_metadata_2025_split huggingface dataset:
Estimating food consumption of marine predators: Antarctic fur seals and macaroni penguins
Authors: Boyd I.L. 
Published: March 2003

Summary

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

Summary

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.
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

Summary 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.