bluuebunny/crossref_metadata_2025 huggingface dataset:
Evidence for cross-talk between stanniocalcins
Authors: Paciga Mark , James Kathi , Gillespie J Ryan J , Wagner Graham F
Published: January 2006

There are 2 forms of stanniocalcin (STC) produced by the STC-1 gene; a 50 kDa polypeptide known as STC50 and a recently discovered group of higher molecular weight variants that are collectively referred to as big STC. Both have different tissue patterns of expression and different intracellular targeting pathways. STC50 functions locally in tissues such as muscle, liver, and kidney and is targeted to mitochondria. Big STC, on the other hand, is made by the ovaries. It signals both locally on nearby corpus luteal cells and systemically. Interestingly, however, receptor binding assays employing STC50 as the tracer have shown that the smaller ligand can bind equally to tissue receptors targeted by either form of the hormone. This suggests there may be cross-talk between ligands. The present study provides credence to this notion by demonstrating how the 2 hormones can compete for tissue receptors normally targeted by 1 form of the hormone (big STC). The results also reveal how STC50 can completely block the inhibitory effects of big STC on luteal cell progesterone release when added simultaneously. The findings therefore add credence to the possibility that there may be circumstances during which the 2 ligands functionally antagonize each other's actions.Key words: stanniocalcin (STC), STC50, big STC, receptor, antagonism, progesterone release.
Modulation ofICa-Lby α1-adrenergic stimulation in rat ventricular myocytes
Authors: Zhang Shetuan , Lin Jijin , Hirano Yuji , Hiraoka Masayasu
Published: January 2006

We found when L-type calcium current (ICa-L) was recorded with the perforated patch-clamp method in rat ventricular myocytes that bath application of phenylephrine (with propranolol) evoked a biphasic response characterized by an initial transient suppression followed by a sustained potentiation. The transient suppression occurred 30–60 s after phenylephrine perfusion and reached peak inhibition at approximately 2 min. The biphasic modulation of ICa-Lwas also elicited by methoxamine, and the effects of phenylephrine were blocked by prazosin, indicating that the responses were mediated through α1-adrenoceptors. Pretreatment of cells with H7 (100 µmol/L), a broad-spectrum protein kinase inhibitor that inhibits both protein kinase C and A, eliminated potentiation but did not affect transient suppression. The transient suppression occurred concurrently with the acceleration of the fast component of ICa-Linactivation. Depletion of intracellular Ca2+stores by ryanodine plus caffeine or thapsigargin eliminated the transient suppression. When ICa-Lwas recorded with whole-cell patch-clamp and with 0.05 mmol/L EGTA in the pipette solution to allow intracellular Ca2+to fluctuate, phenylephrine evoked a transient suppression as in the perforated patch recordings. Heparin, a specific blocker of IP3(inositol 1,4,5-trisphosphate) receptors, eliminated the phenylephrine-induced transient suppression of ICa-Lwhen added to the pipette solution. Intensive chelation of intracellular Ca2+by 5 mmol/L BAPTA (1,2-bis(2-aminophenoxy)ethane-N,N,N′,N′-tetraacetic acid) in the pipette solution also eliminated the phenylephrine-induced transient suppression of ICa-L. We conclude that transient increase in the concentration of intracellular calcium ([Ca2+]i) caused by Ca2+release from intracellular stores underlies the transient suppression of ICa-L, whereas the potentiation of ICa-Lis a result of activation of protein kinases.Key words: Ca2+mobilization, IP3, Ca2+-induced inactivation of Ca2+current, perforated patch-clamp.
Prenatal cocaine alone and combined with nicotine alters ANG II and IGF-1 induced left atrial contractions in aging male offspring
Authors: Scheer Alexandre , Haddad Georges E , Clarke Jr Elijah , Arguinzoni Jason K , Sobrian Sonya K
Published: January 2006

Prenatal cocaine or nicotine affects inotropic activity in the hearts of rat offspring. However, the long-term consequence of this exposure on the cardiac response to hormonal challenge is unknown. We assessed the inotropic effects of angiotensin II (ANG II) and insulin-like growth factor 1 (IGF-1) in the left atria of 19.0–24.5 month-old male rats exposed on gestation days 8–21 to 1 of 6 treatments: low cocaine (LC) (20 mg/kg) or high cocaine (HC) (40 mg/kg); 20 mg/kg cocaine and high nicotine (5 mg/kg nicotine) (LC/HN); 40 mg/kg cocaine and low nicotine (2.5 mg/kg nicotine) (HC/LN); pair fed: yoked to HC (PF); saline: injection of 0.9% NaCl (SAL). Isometric contractions were assessed by electrical stimulation of isolated left atria superfused with Tyrode solution (control) to which ANG II (10–7mol/L, 20 min) and IGF-1 (10–8mol/L, 20 min) in the presence of ANG II were added sequentially. Offspring in all cocaine groups showed a higher peak tension development (PTD) to ANG II than PF controls. This increase in PTD was attenuated by subsequent addition of IGF-1 in all except HC offspring. However, with the HC/LN combination the IGF-1 effect on PTD was again evident. The velocities of contraction and relaxation were positively affected by ANG II only in the combined prenatal drug groups; IGF-1 reduced only contraction velocity. Our data demonstrate that IGF-1 reverses the positive inotropic effect of ANG-II in atrial muscle of aging rats and that gestational exposure to only high doses of cocaine eliminates this protective response. It appears that combined prenatal exposure to cocaine and nicotine does not exacerbate the decline in cardiac function and responsiveness to inotropic drugs seen in the aging heart.Key words: prenatal exposure, cocaine, nicotine, angiotensin II, IGF-1, heart, aging offspring.
Effects of diltiazem or verapamil on calcium uptake and release from chicken skeletal muscle sarcoplasmic reticulum
Authors: Paydar Mehrak Javadi , Pousti Abbas , Farsam Hasan , Amanlou Massoud , Mehr Shahram Ejtemaei , Dehpour Ahmad Reza
Published: January 2006

The purpose of this study was to determine the effects of 2 Ca2+channel blockers, verapamil and diltiazem, on calcium loading (active Ca2+uptake) and the following Ca2+release induced by silver ion (Ag+) and Ca2+from the membrane of heavy sarcoplasmic reticulum (SR) of chicken skeletal muscle. A fluorescent probe technique was employed to determine the calcium movement through the SR. Pretreatment of the medium with diltiazem and verapamil resulted in a significant decrease in the active Ca2+uptake, with IC50of about 290 µmol/L for verapamil and 260 µmol/L for diltiazem. Inhibition of Ca2+uptake was not due to the development of a substantial drug-dependent leak of Ca2+from the SR. It might, in part, have been mediated by a direct inhibitory effect of these drugs on the Ca2+ATPase activity of the SR Ca2+pump. We confirmed that Ca2+channel blockers, administered after SR Ca2+loading and before induction of Ca2+release, caused a dose-dependent inhibition of both Ca2+- and Ag+-induced Ca2+release rate. Moreover, if Ca2+channel blockers were administered prior to SR Ca2+loading, in spite of Ca2+uptake inhibition the same reduction in Ca2+- and Ag+-induced Ca2+release rate was seen. We showed that the inhibition of Ag+-induced Ca2+release by L-channel blockers is more sensitive than Ca2+-induced Ca2+release inhibition, so the IC50for Ag+- and Ca2+-induced Ca2+release was about 100 and 310 µmol/L for verapamil and 79 and 330 µmol/L for diltiazem, respectively. Our results support the evidence that Ca2+channel blockers affect muscle microsome of chicken skeletal muscle by 2 independent mechanisms: first, reduction of Ca2+uptake rate and Ca2+-ATPase activity inhibition, and second, inhibition of both Ag+- and Ca2+-induced Ca2+release by Ca2+release channels. These findings confirm the direct effect of Ca2+channel blockers on calcium release channels. Our results suggest that even if the SR is incompletely preloaded with Ca2+because of inhibition of Ca2+uptake by verapamil and diltiazem, no impairment in Ca2+release occurs. Key words: calcium, sarcoplasmic reticulum, diltiazem, verapamil, chicken, skeletal muscle.
Fever and lethargy induced by subcutaneous pyrogen infusion in unrestrained rats
Authors: du Plessis I , Mitchell D , Laburn H P , Cartmell T
Published: January 2006

We have investigated the effects of continuous subcutaneous infusion of lipopolysaccharide (LPS), muramyldipeptide (MDP), or saline on abdominal temperature and voluntary activity in unrestrained rats. Both pyrogens were infused via osmotic pumps at a rate of ~2 µg·kg–1·min–1for 7 d. LPS infusion evoked a 3-d and MDP a 1-d elevation in body temperature. Night-time activity was suppressed on days 1 and 2 during LPS infusion and on day 1 of MDP infusion. Body mass was significantly decreased on infusion day 4 in rats receiving either LPS or MDP; however, the rate of weight gain had been restored by day 8 (1 d after cessation of pyrogen infusion). We further tested the body temperature response of the same experimental animals to a single subcutaneous bolus injection (250 µg/kg) of the same pyrogen that had been infused for 7 d, 2 d after cessation of pyrogen infusion (day 9). The fever response in rats receiving a bolus injection of either LPS or MDP was significantly attenuated in rats that had previously been infused with the same pyrogen. These data suggest that tolerance developed to continuous infusion of both Gram-negative and Gram-positive pyrogens, and that mechanisms of tolerance development set in early during the 7-d infusion period of both pyrogens and persisted for at least 2 d after the cessation of pyrogen infusion. We propose that cytokine intermediates were involved or required in inducing these responses to continuous infusion of both LPS and MDP.Key words: lipopolysaccharide, muramyldipeptide, rats, osmotic pump, tolerance, Gram-negative, Gram-positive, sickness behavior.
Role of aldosterone in angiotensin II-induced cardiac and aortic inflammation, fibrosis, and hypertrophy
Authors: Neves Mario Fritsch , Amiri Farhad , Virdis Agostino , Diep Quy N , Schiffrin Ernesto L
Published: January 2006

Activation of the renin–angiotensin–aldosterone system is associated with increased extracellular matrix and inflammatory markers in the cardiovascular system. We evaluated the effects of aldosterone antagonism on cardiovascular structure, collagen deposition, and expression of inflammatory markers in 2-week angiotensin (Ang) II-infused rats (120 ng·kg–1·min–1, s.c.) ± spironolactone or hydralazine (25 mg·kg–1·d–1). Aortic and cardiac collagen density was evaluated with Sirius red staining. NFκB and AP-1 were measured by a electrophoretic mobility shift assay, and ED-1 (macrophage marker) and vascular cell adhesion molecule-1 (VCAM-1) were measured by immunohistochemistry. Ang II increased blood pressure (176 ± 2 mmHg vs. 115 ± 1 mmHg in controls, p < 0.01), which was attenuated by spironolactone (147 ± 4 mmHg, p < 0.01) and prevented by hydralazine (124 ± 2 mmHg, p < 0.01). Ang II enhanced left ventricular interstitial collagen type I/III deposition (4.1% ± 0.1% vs. 3.1% ± 0.2%, p < 0.05), and this was attenuated by spironolactone but not hydralazine. Ang II-induced cardiac perivascular fibrosis was prevented by spironolactone and hydralazine. Ang II significantly increased cardiac AP-1 activity and ED-1 expression, which was prevented by spironolactone only. Ang II-enhanced NFκB activity, and VCAM-1 expression was reduced by spironolactone and hydralazine, whereas aortic hypertrophy was prevented by spironolactone and slightly reduced by hydralazine. In conclusion, blockade of mineralocorticoid receptors with spironolactone inhibited Ang II-induced aortic hypertrophy, cardiac transcription factor activation, upregulation of downstream inflammatory markers, and collagen deposition, thus preventing Ang II-induced cardiovascular damage.Key words: collagen, heart, aorta, spironolactone, inflammation.
Modulation of Na+transport and epithelial sodium channel expression by protein kinase C in rat alveolar epithelial cells
Authors: Yamagata Toshiyuki , Yamagata Yuko , Massé Chantal , Tessier Marie-Claude , Brochiero Emmanuelle , Dagenais André , Berthiaume Yves
Published: January 2006

Although the amiloride-sensitive epithelial sodium channel (ENaC) plays an important role in the modulation of alveolar liquid clearance, the precise mechanism of its regulation in alveolar epithelial cells is still under investigation. Protein kinase C (PKC) has been shown to alter ENaC expression and activity in renal epithelial cells, but much less is known about its role in alveolar epithelial cells. The objective of this study was to determine whether PKC activation modulates ENaC expression and transepithelial Na+transport in cultured rat alveolar epithelial cells. Alveolar type II cells were isolated and cultured for 3 to 4 d before they were stimulated with phorbol 12-myristate 13-acetate (PMA 100 nmol/L) for 4 to 24 h. PMA treatment significantly decreased α, β, and γENaC expression in a time-dependent manner, whereas an inactive form of phorbol ester had no apparent effect. This inhibitory action was seen with only 5-min exposure to PMA, which suggested that PKC activation was very important for the reduction of αENaC expression. The PKC inhibitors bisindolylmaleimide at 2 µmol/L and Gö6976 at 2 µmol/L diminished the PMA-induced suppression of αENaC expression, while rottlerin at 1 µmol/L had no effect. PMA elicited a decrease in total and amiloride-sensitive current across alveolar epithelial cell monolayers. This decline in amiloride-sensitive current was not blocked by PKC inhibitors except for a partial inhibition with bisindolylmaleimide. PMA induced a decrease in rubidium uptake, indicating potential Na+-K+-ATPase inhibition. However, since ouabain-sensitive current in apically permeabilized epithelial cells was similar in PMA-treated and control cells, the inhibition was most probably related to reduced Na+entry at the apical surface of the cells. We conclude that PKC activation modulates ENaC expression and probably ENaC activity in alveolar epithelial cells. Ca2+-dependent PKC is potentially involved in this response.Key words: alveolar epithelial cells, Na+transport, Na+channel, ENaC, protein kinase C, Na+-K+-ATPase, amiloride, gene expression.
Losartan and acute myocardial infarction in insulin-resistant Zucker fatty rats: reduced ventricular arrhythmias and improved survival
Authors: Pourdjabbar Ali , Parker Thomas G , Desjardins Jean-François , Nguyen Quang Trinh , Tsoporis James N , Lapointe Nathalie , Rouleau Jean-Lucien
Published: January 2006

Insulin resistance (IR) and diabetes increase the risk of acute myocardial infarction (MI). Angiotensin receptor blockers (ARBs) have been shown to reduce the risk of cardiovascular events in patients with hypertension and diabetes, and to be beneficial after a large MI. Whether pretreatment with ARBs is beneficial in acute MI is unknown. We evaluated whether pre-, peri-, and post-MI treatment with the ARB losartan improved the outcome in the IR Zucker fatty rat (ZFR). ZFR (n = 264) received either losartan (3 mg/kg daily) or vehicle for 7 d prior to MI. Early (24 h) protocol (n = 31): ventricular arrhythmias were evaluated post-MI using continuous ambulatory ECG monitoring. Late (38 d) protocol (n = 233): losartan was increased to 10 mg/kg daily 10 d post-MI and to 30 mg/kg daily 20 d post-MI. Blood glucose, cardiac hemodynamics and remodeling, GLUT-4, fetal gene expression, and survival were evaluated. In large-MI rats, losartan improved early survival (43% vs. 27% in controls, p = 0.01) and late survival (23% vs.15% in controls, p = 0.02). Improved early survival was associated with a reduction in ventricular arrhythmias. Losartan reduced pulmonary congestion, cardiac hypertrophy, and fetal gene expression in the absence of statistically significant changes in ventricular dilatation and hemodynamics. Blood glucose and cardiac GLUT-4 expression did not change with losartan. In IR ZFR, losartan improves post-MI survival, likely as a result of an early reduction in ventricular arrhythmias. There was also an associated reduction in pulmonary congestion, hypertrophy, and fetal gene expression.Key words: diabetes, heart failure, myocardial infarction, remodeling, renin–angiotensin system, ventricular arrhythmias.
Peripheral pacemakers and patterns of slow wave propagation in the canine small intestine in vivo
Authors: Lammers Wim J.E.P , Donck Luc Ver , Schuurkes Jan A.J , Stephen Betty
Published: January 2006

In an anesthetized, open-abdomen, canine model, the propagation pattern of the slow wave and its direction, velocity, amplitude, and frequency were investigated in the small intestine of 8 dogs. Electrical recordings were made using a 240-electrode array from 5 different sites, spanning the length of the small intestine. The majority of slow waves propagated uniformly and aborally (84%). In several cases, however, other patterns were found including propagation in the oral direction (11%) and propagation block (2%). In addition, in 69 cases (3%), a slow wave was initiated at a local site beneath the electrode array. Such peripheral pacemakers were found throughout the entire intestine. The frequency, velocity, and amplitude of slow waves were highest in the duodenum and gradually declined along the intestine reaching lowest values in the distal ileum (from 17.4 ± 1.7 c/min to 12.2 ± 0.7 c/min; 10.5 ± 2.4 cm/s to 0.8 ± 0.2 cm/s, and 1.20 ± 0.35 mV to 0.31 ± 0.10 mV, respectively; all p < 0.001). Consequently, the wavelength of the slow wave was strongly reduced from 36.4 ± 0.8 cm to 3.7 ± 0.1 cm (p < 0.001). We conclude that the patterns of slow wave propagation are usually, though not always, uniform in the canine small intestine and that the gradient in the wavelength will influence the patterns of local contractions.Key words: slow waves, conduction velocity, peripheral pacemakers, wavelength.
Age-related alterations in cyclic nucleotide phosphodiesterase activity in dystrophic mouse leg muscle
Authors: Bloom Timothy J
Published: January 2006

Previous reports have described both increased and decreased cyclic nucleotide phosphodiesterase (PDE) activity in dystrophic muscle. Total PDE activity was measured in hind leg muscle from a mouse model of Duchenne muscular dystrophy (mdx) and a genetic control strain at 5, 8, 10, and 15 weeks of age. Total PDE activity declined in fractions isolated from mdx muscle over this time period, but was stable in fractions from control mice. Compared with age-matched controls, younger mdx muscle had higher cAMP and cGMP PDE activity. However, at 15 weeks, fractions from both strains had similar cGMP PDE activity and mdx fractions had lower cAMP PDE activity than controls. Particulate fractions from mdx muscle showed an age-related decline in sensitivity to the PDE4 inhibitor RO 20-1724. A similar loss of sensitivity to the PDE2 inhibitor erythro-9-(2-hydroxyl-3-nonyl)-adenine (EHNA) was seen in a particulate fraction from mdx muscle and to a lesser degree in control muscle. These results suggest that the earlier disagreement regarding altered cyclic nucleotide metabolism in dystrophic muscle may be due to changes with age in PDE activity of dystrophic tissue. The age-related decline in particulate PDE activity seen in dystrophic muscle appears to be isozyme-specific and not due to a generalized decrease in total PDE activity.Key words: cyclic nucleotide phosphodiesterase, muscular dystrophy, mouse, RO 20-1724, EHNA.
Nutrition as a determinant of functional autonomy and quality of life in aging: a research program
Authors: Payette Hélène
Published: January 2006

With the aging of the Canadian population, functional autonomy and quality of life among seniors are now important public health issues. We hypothesized that nutrition is an important determinant of the quality of aging because of its potential to modulate the transitions from vulnerability to frailty and dependence. Over the past 15 years, our research program addressed the prevalence, the determinants, and the consequences of undernutrition among seniors, especially the free-living frail elderly. Very low energy and nutrient intakes were observed as well as a high prevalence of involuntary weight loss. These chronic conditions were associated with early institutionalization and increased mortality rates. Intervention strategies were then developed and evaluated, including the Nutrition Screening Program and the Nutrition Support Program. The effectiveness of these programs was shown with respect to improvement of nutritional status. However, this improvement was not sufficient to produce significant changes in functional autonomy or quality of life. Methodological issues related to the conduct of intervention studies in this specific population were addressed. A conceptual framework of nutritional intervention is currently being validated. A large longitudinal study that is being undertaken will further contribute to our understanding of the aging process as determined by a modifiable factor such as nutrition.Key words: aging, nutrition, autonomy, nutrition screening, nutrition intervention.
Impaired NK cell cytotoxicity by high level of interferon-γ in concanavalin A-induced hepatitis
Authors: Dong Zhongjun , Zhang Cai , Wei Haiming , Sun Rui , Tian Zhigang
Published: January 2006

Unlike T cells, the role of natural killer (NK) cells is not well documented in the concanavalin (ConA)- induced hepatitis model. This study aimed to investigate the regulatory effect of high levels of interferon-γ (IFN-γ) on NK cells in ConA-induced hepatitis. The cytotoxicities of NK cells from ConA-injected mice or NK cell lines (NK92 and NKL) were detected by the 4-h51Cr release assay. Depletion of NK cells with AsGM1 antibody was used to assess the NK cell role in ConA-induced hepatitis. Expression of NK cell receptors and cytotoxic molecules was measured by reverse transcription – polymerase chain reaction. Twelve hours after ConA injection, serum IFN-γ was significantly increased in wild mice, but not in severe combined immunodeficiency mice, and hepatic NK cells exerted impaired cytotoxicity against YAC-l cells in wild mice. Eight hours after NK cells were incubated in serum from ConA-treated mice, NK cell cytotoxicity was down-modulated and the effect was abolished by pretreatment with neutralizing serum IFN-γ with specific antibody in vitro. A high concentration of IFN-γ (> 1000 U/mL) inhibited the cytotoxicities of 2 NK cell lines in vitro, accompanied with down-regulation of NKG2D transcripts and up-regulation of NKG2A/B and KIR2DL transcripts. The inhibitive role of IFN-γ was not seen in NKG2D ligand negative cells. These results suggest that NK cell cytotoxicity was inhibited by high levels of IFN-γ in ConA-induced hepatitis, which may relate to the dispensable role of NK cells.Key words: cytotoxicity, hepatoimmunology, interferon-γ, liver injury.
Characterization of sulfate, proline, and glucose transport systems in anterior cruciate and medial collateral ligament cells
Authors: Bhargava Madhu M , Kinne-Saffran Evamaria , Kinne Rolf K.H , Warren Russell F , Hannafin Jo A
Published: January 2006

The present study was undertaken to define the nature of key transport processes for sodium, glucose, proline, and sulfate in primary culture of canine anterior cruciate ligament (ACL) and medial collateral ligament (MCL) cells. Uptake studies using radiolabeled isotopes were performed and Na,K-ATPase activity was determined in cell lysates. At 25 °C both ACL and MCL cells showed a significant uptake of86Rb. Ouabain inhibited Rb uptake by 55% in ACL cells and by 60% in MCL cells. The transport activity of Na,K-ATPase in intact cells was calculated to be 57 and 71 nmol·(mg protein)–1·(15 min)–1, respectively. The enzymatic activity of Na,K-ATPase in cell lysates was observed to be 104 for ACL cells and 121 nmol·(mg protein)–1·(15 min)–1for MCL cells. Cytochalasin B, a known inhibitor of sodium-independent D-glucose transport, completely inhibited D-glucose uptake in ACL and MCL cells. Removal of Na+or addition of 10–5mol/L phlorizin, a potent inhibitor of the sodium-D-glucose cotransporter, did not alter D-glucose uptake, suggesting that glucose entered the cells using a sodium-independent pathway. Both ACL and MCL cells exhibited high sulfate uptake that was not altered by replacement of Na+by N-methyl-D-glucamine, whereas DIDS, an inhibitor of sulfate/anion exchange abolished sulfate uptake in both cell types. Thus, neither cell type seems to possess a sodium-sulfate cotransport system. Rather, sulfate uptake appeared to be mediated by sulfate/anion exchange. Proline was rapidly taken up by ACL and MCL cells and its uptake was reduced by 85% when Na+was replaced by N-methyl-D-glucamine, indicating that proline entered the cells via sodium-dependent cotransport systems. The data demonstrate that both ACL and MCL cells possess a highly active sodium pump, a secondary active sodium-proline cotransport system, and sodium-independent transport systems for D-glucose and sulfate.Key words: ligament, fibroblasts, transport, proline, sulfate, glucose, sodium.
Locomotor morphometry of the Pachydactylus radiation of lizards (Gekkota: Gekkonidae): a phylogenetically and ecologically informed analysis
Authors: Johnson Megan K , Russell Anthony P , Bauer Aaron M
Published: January 2006

The Pachydactylus radiation comprises a diverse group of African gekkonids that exploit a variety of microhabitats and exhibit both climbing and terrestrial locomotion. The phylogeny of this radiation is well supported, making it a promising candidate for the investigation of relationships between limb proportions, ecology, and behaviour. Skeletal and external measurements were recorded for an array of taxa and analyzed using principal components analysis (PCA). The results of the PCAs were further analyzed using phylogenetic statistical methods to ascertain whether climbing and terrestrial species and (or) clades within the radiation differed significantly from each other in limb proportions. Phylogenetically based comparisons revealed that although there is some differentiation between climbing and terrestrial species, this is not a general pattern but is primarily attributable to certain species and clades within the radiation that differ considerably from other members of the group. The results indicate that Chondrodactylus angulifer Peters, 1870 possesses shortened distal phalanges and that Pachydactylus rangei (Andersson, 1908), P. austeni Hewitt, 1923, and the Rhoptropus clade (particularly R. afer Peters, 1869) possess elongated limbs relative to the rest of the radiation. These differences correlate with aspects of the lifestyles of these species, such as increased terrestriality, a reduction or loss of the subdigital adhesive apparatus, digging behaviour, and a transition to diurnality.
Individual variation in milk composition over lactation in harbour seals (Phoca vitulina) and the potential consequences of intermittent attendance
Authors: Lang S L.C , Iverson S J , Bowen W D
Published: January 2006

We studied milk composition over the course of lactation in 21 harbour seal (Phoca vitulina L., 1758) females on Sable Island, Nova Scotia. Milk fat content increased significantly from 40.8% ± 1.01% at parturition to 50.2% ± 1.39% at day 7 and then remained relatively constant throughout the remainder of lactation. Changes in dry matter mirrored changes in fat content. Protein content averaged about 9% over mid to late lactation. There was considerable between-individual variation in the composition of milk and how it changed over lactation, particularly in milk fat content (CV 9.1%–11.4%). In three females that were separated from their pups for 4–6 days, milk fat content declined by 20%–23% and milk protein content increased by 6%–11%. These changes in milk composition indicate that changes in mammary gland function occur rapidly following the onset of milk stasis in harbour seals. The rapid response of the mammary glands to separation suggests that, in direct contrast to the glands of otariids, the glands of harbour seals rely on regular evacuation to maintain normal function. These results suggest that there may be a significant physiological constraint on the duration that harbour seal females, and presumably other phocid seals, can forage without negatively affecting energy transfer to their pups.
Comparison between shell morphology and genetic diversity in two sympatric lymnaeid snails, vectors of fasciolosis
Authors: Hurtrez-Boussès S , Pendino A , Barnabé C , Durand P , Rondelaud D , Durand C , Meunier C , Hurtrez J-E , Renaud F
Published: January 2006

Species determination of freshwater snails is particularly important in the case of disease vectors. In central France, for example, it has been shown that Galba truncatula (Müller, 1774) and Omphiscola glabra (Müller, 1774), which can be found in sympatry, are intermediate hosts for fasciolosis. Although these two species are distinguishable based on their shell morphology, some snails present in sympatric zones possess shell characteristics that are common to both species, suggesting possible gene flow. To test this hypothesis, we carried out multilocus enzyme electrophoreses on individuals sampled in one zone of sympatry. Our results clearly show that all snails with shell characteristics common to both species are O. glabra. We also note an absence of hybridization between G. truncatula and O. glabra in the study area. Remarkably, we observe a total monomorphism at the six studied loci among individuals of G. truncatula. Similarly, we find a total lack of heterozygotes in the O. glabra sample (with classic or intermediate shell characteristics). These results suggest a predominance of selfing in the reproductive mode of both species. Our results suggest that conchological characteristics can provide information about the taxonomic position of lymnaeids. However, they are insufficient to confidently differentiate species.
Indirect effects of fish winterkills on amphibian populations in boreal lakes
Authors: Eaton B R , Tonn W M , Paszkowski C A , Danylchuk A J , Boss S M
Published: January 2006

We exploited fish winterkills in small, boreal Alberta lakes to determine if anuran amphibians respond to large but natural changes in fish densities. Eight large declines in fish abundance occurred in seven lakes over a 5 year period, while major increases in fish abundance, reflecting recovery after winterkill, were recorded 5 times. Summer pitfall trapping of young-of-the-year (YOY) Wood Frogs (Rana sylvatica LeConte, 1825) and Boreal (Bufo boreas boreas Baird and Girard, 1852) and Canadian (Bufo hemiophrys Cope, 1886) toads indicated that frog abundance responded consistently to such large changes in fish abundance, but especially if fish communities were dominated by small-bodied species (sticklebacks and minnows). As well, changes in YOY Wood Frog and fish abundance were negatively correlated; YOY Wood Frogs were as much as 7.7 times more abundant after winterkills than in non-winterkill years. These increases in metamorphs did not result from an increased immigration of breeding adults to winterkill lakes, suggesting instead that larval survival was greater. Higher abundance of YOY Wood Frogs and toads was associated with smaller body size at metamorphosis. Despite this apparent reduction in individual growth, abundance of juvenile frogs remained significantly elevated 1 year after winterkill. In contrast to Wood Frogs, YOY toads tended to respond positively to recoveries of small-fish populations. Because anuran amphibians can respond to fish winterkill, and because winterkill is a frequent natural disturbance, small fish-bearing lakes can serve as important breeding habitat for amphibians in Alberta's boreal forest.
Superoxide dismutase, catalase, and glutathione peroxidase during epididymal maturation and prolonged storage of spermatozoa in the Mexican big-eared bat (Corynorhinus mexicanus)
Authors: Arenas-Ríos E , León-Galván M A , Mercado P E , Rosado A
Published: January 2006

We studied the activities of reactive oxygen species (ROS) scavenging enzymes during epididymal spermatozoon maturation and storage in Corynorhinus mexicanus (G.M. Allen, 1916), a vespertilionid bat that stores spermatozoa in the epididymides for several months after regression of the testes. Depending on the phase of the epididymal reproductive cycle, two different patterns of antioxidant enzyme activities were observed in C. mexicanus. Catalase activity is clearly present in both caput and cauda epididymides throughout the entire annual reproductive cycle, being particularly high during the post-testicular phase of epididymal function. Superoxide dismutase (SOD) activity, present during the testicular phase of epididymal transport and maturation of spermatozoa, is almost completely absent or inhibited in both epididymal segments during the post-testicular epididymal storage period. GPx activity is low during the testicular phase of epididymal spermatozoon maturation and is high in both epididymal segments during the storage phase of epididymal function. From our results, we postulate that (i) the pattern of epididymal antioxidant enzyme activities in C. mexicanus is significantly different from the pattern that is proposed to be unique for mammals; (ii) epididymal function in these species of bats can be clearly divided into two phases, a testicular-dependent phase that is related to the spermatozoon maturation function of the epididymides and a testicular-independent phase that is related to the long-term spermatozoon storage function observed in these mammals; (iii) the study of the regulation of the redox potential of the microenvironment, associated with mammalian spermatozoa as they transit through the epididymides, must be particularly focused on the anatomical region where ROS generation scavenging and spermatozoon maturation storage processes take place.
Molecular phylogenetics and biogeography of Bunodera spp. (Trematoda: Allocreadiidae), parasites of percid and gasterosteid fishes
Authors: Choudhury A , Règagnon V León
Published: January 2006

The genus Bunodera Railliet, 1896 is represented by five freshwater species: the holarctic B. luciopercae (Müller, 1776) in percids; the endemic North American B. sacculata VanCleave and Mueller, 1932 in percids; B. eucaliae (Miller, 1936) and B. inconstans (Lasee, Font and Sutherland, 1988) in freshwater sticklebacks; and the trans-Pacific B. mediovitellata Tsimbaliuk and Roytman, 1966 in the threespine stickleback (Gasterosteus aculeatus L., 1758). Partial sequences of the 28S ribosomal RNA gene were combined with morphological data for a phylogenetic analysis of Bunodera spp. Parsimony analysis of the combined data yielded a tree (consistency index = 0.84) that supports the following resolution: ((((B. luciopercae(((B. sacculata((B. mediovitellata(B. eucaliae + B. inconstans)))). The basal position of B. luciopercae is consistent with its holarctic distribution and a basal percid as its main host. The relatively basal positions of two typical perch parasites and the association of a more derived clade (B. mediovitellata + B. eucaliae + B. inconstans) with sticklebacks indicate host shifting from percids to sticklebacks. The sister relationships and North American endemicity of the two most derived species, B. eucaliae and B. inconstans, are also consistent with the more derived position of their typical host, the freshwater brook stickleback (Culaea inconstans (Kirtland, 1841)).
The effects of nesting success and mate fidelity on breeding dispersal in burrowing owls
Authors: Catlin D H , Rosenberg D K , Haley K L
Published: January 2006

Understanding and describing the factors that affect avian breeding dispersal are critical for modeling population dynamics and designing conservation strategies. We investigated the hypothesis that dispersal probability and dispersal distance are affected by nesting success and mate fidelity with band–resight data (1998–2003) from burrowing owls (Athene cunicularia (Molina, 1782)) nesting in southern California. Most owls (167 of 253, 66%) remained near their initial nest (<100 m), and those that moved >100 m dispersed 472 ± 65 m (mean ± 1 SE; n = 86). Both female and male owls whose nests failed were more likely to disperse and dispersed longer distances than owls with successful nests. Failed nesting attempts were also associated with an increased probability of divorce, and divorce was related to increased dispersal probabilities and distances. Moreover, female and male owls tended to be more likely to disperse and to disperse greater distances following the death of a mate than those that remained paired. Although dispersal was related to mate fidelity, nesting success remained an important factor affecting dispersal even after controlling for the effects of mate loss. Our results suggest that nesting failure was the primary factor associated with dispersal probability and dispersal distance in burrowing owls in our population.
Behaviourally specific preferred associations in bottlenose dolphins, Tursiops spp.
Authors: Gero S , Bejder L , Whitehead H , Mann J , Connor R C
Published: January 2006

We investigated association patterns of 52 photographically identified, free-ranging bottlenose dolphins (Tursiops spp. Gervais, 1855) across four behavioural states (rest, travel, social, and foraging/feeding) to investigate how behavioural state influences patterns of association. Group composition and behavioural data were extracted from 2178 encounter surveys collected over 3 years. Analyses revealed three general types of association: (1) affiliates, which consistently demonstrate preferred associations across all behavioural states; (2) acquaintances, which never form preferred associations but still associate in at least one behavioural state; and (3) behavioural associates, which form preferred associations in at least one, but not all behavioural states. The majority of associations in Shark Bay, Australia, are acquaintance type (38.2%), with affiliates (5.7%, principally between adult males) and behavioural associates (28.9%, principally between juveniles) being relatively rarer. Permutation tests identified behaviourally specific preferred associations during all behavioural states. Although behaviourally specific preferred associations appear to exist within the Shark Bay social structure, it seems that the social organization and mating system constrain the social relationships for the majority of males and females in differing ways which prevent them from having behavioural associates, leaving juveniles free to associate based on short-term expediency and behavioural specific needs.
Factors affecting carcass use by a guild of scavengers in European temperate woodland
Authors: Selva N , Jędrzejewska B , Jędrzejewski W , Wajrak A
Published: January 2006

Although facultative scavenging is very common, little is known about the factors governing carrion acquisition by vertebrates. We examined the influence of carcass characteristics, carcass state, and weather conditions on carrion use by main scavengers. Carcasses (N = 214, mainly ungulates) of various origins (predation, natural deaths, harvest) were monitored by systematic inspections (N = 1784) in Białowieża Forest (Poland). Common raven (Corvus corax L., 1758), red fox (Vulpes vulpes (L., 1758)), and European pine marten (Martes martes (L., 1758)) mainly used the prey remains of gray wolves (Canis lupus L., 1758). The kills of predators were the preferred carrion, rather than dead ungulates. Common ravens, common buzzards (Buteo buteo (L., 1758)), white-tailed eagles (Haliaeetus albicilla (L., 1758)), and domestic dogs scavenged more frequently on carcasses in open habitats. Carcasses located in the forest were the most available to European pine martens, jays (Garrulus glandarius (L., 1758)), and wild boar (Sus scrofa L., 1758). The common tendency was to increase scavenging when temperature decreased, except for raccoon dogs (Nyctereutes procyonoides (Gray 1834)). As snow depth increased, jays and great tits (Parus major L., 1758) increased scavenging. We suggest that carrion use by scavengers is not random, but a complex process mediated by extrinsic factors and by behavioural adaptations of scavengers.
A reconnaissance of population genetic variation in arctic and subarctic sulfur butterflies (Coliasspp.; Lepidoptera, Pieridae)
Authors: Wheat Christopher W , Watt Ward B , Boutwell Christian L
Published: January 2006

Genotype–phenotype–environment interactions in temperate-zone species of Colias Fabricius, 1807 have been well studied in evolutionary terms. Arctic and alpine habitats present a different range of ecological, especially thermal, conditions under which such work could be extended across species and higher clades. To this end, we survey variation in three genes that code for phosphoglucose isomerase (PGI), phosphoglucomutase (PGM), and glucose-6-phosphate dehydrogenase (G6PD) in seven arctic and alpine Colias taxa (one only for G6PD). These genes are highly polymorphic in all taxa studied. Patterns of variation for the PGI gene in these northern taxa suggest that the balancing selection seen at this gene in temperate-zone taxa may extend throughout northern North America. Comparative study of these taxa may thus give insight into the mechanisms driving genetic differentiation among subspecies, species, and broader clades, supporting the study of both micro- and macro-evolutionary questions.
Winter torpor in Helix pomatia: regulated defence mechanism or forced inactivity?
Authors: Caputa M , Nowakowska A , Rogalska J , Wentowska K
Published: January 2006

We examined Helix pomatia L., 1758 snails to answer two questions. First, is their winter dormancy facilitated by cold-seeking behaviour, or is it rather a passive phenomenon imposed by cold weather? Second, what thermal conditions are necessary to arouse these snails out of torpor in midwinter and in spring? Snails, collected from natural habitats, were placed in a temperature-gradient apparatus. Their thermal preference was recorded for 48 h under natural photoperiod in early spring, midsummer, and autumn. The autumn recording was continued until the end of November on non-starved and starved snails. Two additional sessions were performed on torpid snails in January (latencies of arousals from torpor at various temperatures and immediate thermal preferences were recorded) and in February (they were kept permanently in darkness at 5 °C and their spontaneous arousals were examined). Temperature selected in spring (23.60 ± 0.15 °C) was significantly lower than that in summer (26.90 ± 0.05; P < 0.05) and in autumn (27.50 ± 0.10 °C; P < 0.01). The prolonged autumn recording did not show cold-seeking behaviour either in non-starved or in starved snails. Threshold temperature inducing midwinter arousals was 10 °C and the aroused snails immediately selected temperatures indistinguishable from those in summer and autumn. Spontaneous arousals from torpor in the snails continuously exposed to cold occurred within a period of arousals in the field. In conclusion, winter torpor of the snails displays unique properties, i.e., its start and maintenance are passive phenomena, while its spring interruption is a precisely controlled, endogenous mechanism.
Source of alarm substances in crayfish and their preliminary chemical characterization
Authors: Acquistapace Patrizia , Calamai Luca , Hazlett Brian A , Gherardi Francesca
Published: January 2006

We tested the hypothesis that hemolymph contains alarm substances in the crayfish Procambarus clarkii (Girard, 1852) and collected preliminary information on their chemical nature in this species. We analyzed crayfish responses in the presence of different test solutions in four experiments. The crayfish displayed an alerted behavior (i.e., feeding and locomotion were inhibited) in the presence of solutions containing different concentrations of hemolymph combined with food odor. However, hemolymph lost its bioactivity when tested 24 h after its extraction but maintained its ability to elicit alerted responses when diluted in a solution containing L-ascorbic acid. This may suggest that crayfish alarm molecules are degraded with time by oxidation. Microbial activity did not lead to the degradation of alarm substances, since hemolymph activity still declined after 24 h even if extracted and preserved in sterile conditions. Hemolymph molecules less than 5 kDa fractionated from hemolymph showed a strong bioactivity and were still bioactive after 24 h at 20 °C. As the 5 kDa fractioning eliminates all enzymes, we hypothesize that alarm substances are degraded through enzymatic reactions. Finally, we propose that alarm substances are peptides involved in the hemolymph clotting process.
Gender- and age-class-specific reactions to human disturbance in a sexually dimorphic ungulate
Authors: Loehr J , Kovanen M , Carey J , Högmander H , Jurasz C , Kärkkäinen S , Suhonen J , Ylönen H
Published: January 2006

According to optimality theory, an individual's characteristics should play a major part in determining antipredator strategies. We studied behavioural reactions to human presence of gender and age classes of 35 thinhorn sheep (Ovis dalli Nelson, 1884) in late winter 2001 in Faro, Yukon Territory, Canada. The behaviour of undisturbed sheep was observed from distances of 400–1200 m and compared with the behaviour recorded when one or two people were in close proximity to the sheep. Ewes decreased bedding and increased foraging when humans were present, but there were no changes in these behaviours in rams. Disturbance caused an increase in vigilance and a trend was found for adults to react more strongly to disturbance than juveniles. We demonstrate the importance for disturbance research of gaining detailed information about all different kinds of population members and using applicable statistical tests in the data analyses.
Do behavioural and life-history traits vary with mate-guarding intensity in libellulid odonates?
Authors: Koch K , Suhling F
Published: January 2006

It has been demonstrated that in libellulid dragonflies the distribution of eggs during oviposition and the offspring size vary with the type of mate guarding during oviposition (non-contact guarding and contact guarding). In this study, we investigated the hypothesis that oviposition behaviour and life-history traits also differ between these two guarding types. Therefore, we studied oviposition behaviour and life-history traits in six species of a dragonfly assemblage of the Namib Desert. Among the oviposition behaviours, oviposition duration and number of pond changes differed significantly between the guarding types. Clutch size did not differ between the guarding types, whereas some offspring characters, namely egg width, temperature sum to hatch, and larval head width, differed between the guarding types. Eggs of tandem species (those performing contact guarding) were larger, which might explain differences in all other offspring characters studied; bigger eggs need a lower temperature sum for egg development, result in bigger larvae, and have a faster growth rate, all traits that might be seen as an adapation to temporary waters, which are major habitats of the tandem species. This observation is discussed in the light of different dispersal strategies between the species performing different guarding types.