bluuebunny/crossref_metadata_2025_split huggingface dataset:
Ontogenic changes in lactoferrin receptor and DMT1 in mouse small intestine: implications for iron absorption during early lifeThis paper is one of a selection of papers published in this Special Issue, entitled 7th International Conference on Lactoferrin: Structure, Function, and Applications, and has undergone the Journal's usual peer review process.
Authors: Lopez Veronica , Suzuki Yasushi A. , Lönnerdal Bo 
Published: August 2006

It has been proposed that lactoferrin receptor (LfR) may be involved in intestinal iron transport during early life. However, it is known that iron homeostasis is regulated by divalent metal transporter 1 (DMT1; Nramp2/DCT1) in the adult small intestine. To address the hypothesis that LfR may play a role as an alternative iron transport pathway during early life, we used immunohistochemistry (IHC) to examine the localization of mouse LfR (mLfR) and DMT1. In addition to studying the localization and abundance of LfR and DMT1 on the apical membrane, intestinal brush-border membrane vesicles (BBMV) were isolated during the first 3 postnatal weeks (postnatal day (PD) 0, 5, 10, and 20). We found that mLfR is expressed in fetal mice as early as gestational days (GD) 13.5, 15.5, and 18.5. A 34 kD band for mLfR was detected at PD 0 through PD 20 in total intestine homogenate. However, mLfR protein did not appear in the BBMV preparations until PD 5 and was highly expressed at PD 10. By IHC, DMT1 protein was minimally observed at PD 0 and PD 5, but by PD 10 DMT1 was predominantly localized in the apical membrane of the maturing intestine. BBMV fractionation revealed 50–120 kD protein bands for DMT1. In these BBMV preparations, the apical-membrane-associated 120 kD band for DMT1 increased in abundance with age. However, in the corresponding total homogenates, only the deglycosylated form of DMT1 (50 kD) was identified. These results indicate that DMT1 is mislocalized during late gestation, minimally expressed during early life, and predominantly expressed in its deglycosylated form until PD 20. The immunolocalization and abundant protein expression of mLfR suggest that accrual of iron from Lf may be the principal iron uptake pathway at this age. In conclusion, our findings support the notion that until the development-dependent expression of DMT1 in the intestine is induced, mLfR may serve as an alternative iron uptake pathway.
Oxidative balance and immunodetection of antioxidant enzymes in the hepatopancreas of the crabChasmagnathus granulatasubjected to anoxia and reoxygenation
Authors: de Oliveira Ubirajara O. , Belló-Klein Adriane , Kucharski Luiz Carlos 
Published: August 2006

The present study shows the activities and concentrations of the antioxidant enzymes superoxide dismutase (SOD) and glutathione S-transferase (GST) in the hepatopancreas of the crab Chasmagnathus granulata (Dana, 1851) (Decapoda, Brachyura) when exposed to periods of anoxia (8 h) and aerobic recovery (20 and 40 min post anoxia). Exposure to anoxia did not cause any change in the activities of the enzymes analyzed. The activities of these enzymes did not change with a decrease in environmental oxygen concentration. During reoxygenation, enzyme activities returned to control levels. The concentrations and activities of SOD and GST presented different response profiles. Exposure to anoxia caused increased lipoperoxidation (conjugated dienes and thiobarbituric acid reactive substances), whereas aerobic recovery reduced lipoperoxidation. The results of this study showed that C. granulata adjusts its antioxidant defense systems in an attempt to reduce and (or) avoid damage resulting from the reintroduction of oxygen.
Minimal overwintering temperatures of red-sided garter snakes (Thamnophis sirtalis parietalis): a possible cue for emergence?
Authors: Lutterschmidt Deborah I. , LeMaster Michael P. , Mason Robert T. 
Published: August 2006

Red-sided garter snakes ( Thamnophis sirtalis parietalis (Say in James, 1823)) in Manitoba, Canada, undergo 8 months of continuous winter dormancy prior to spring emergence. As in other ectothermic species, increases in ground temperature may be the cue for emergence from winter dormancy in these populations. To test this hypothesis, we measured body temperatures during winter dormancy by surgically implanting small temperature loggers into 32 female red-sided garter snakes before they entered their native hibernaculum. The following spring, we recaptured seven of the snakes implanted with temperature loggers. Body temperature declined gradually from mid-September (14.7 ± 0.24 °C, mean ± SE) to early April (1.1 ± 0.16 °C, mean ± SE) during winter dormancy, reaching minimal values approximately 1 month prior to spring emergence. Body temperatures of emerging snakes ranged from 0.5 °C during early spring to 6.3 °C during late spring (3.4 ± 0.84 °C, mean ± SE). These results do not support the hypothesis that an increase in ground temperature (and hence body temperature) is necessary for emergence from winter dormancy. We suggest that critically low temperatures (i.e., 0.5–1 °C) are a Zeitgeber entraining an endogenous circannual cycle that regulates snake emergence. These results offer new insight into the mechanisms regulating seasonal emergence from winter dormancy.
Parasite-induced anorexia in a free-ranging mammalian herbivore: an experimental test using Soay sheep
Authors: Jones O.R. , Anderson R.M. , Pilkington J.G. 
Published: August 2006

Theory suggests that gastrointestinal parasites can influence herbivore population dynamics by increasing host mortality rates. In addition, parasites may have a non-lethal range of both physiological and behavioural effects on their hosts. Two potential behavioural effects are parasite-induced anorexia and the alteration of diet selection patterns — both of which may influence plant communities without necessarily causing herbivore mortality. We report here the results of an experiment carried out in August–September 2001 to examine herbivore response to parasitism using feral Soay sheep ( Ovis aries L., 1758) living on Hirta, St. Kilda (Scotland, UK), as a model system. The aim of the experiment was to determine whether the sheep exhibit significant parasite-induced anorexia and whether diet selectivity was also altered in response to parasitism. The n-alkane technique was used to estimate forage intake rates and diet composition. Overall, intake rate increased with body mass and the mean (±SE) over both sexes was 737 ± 40 g DM / day (range 458–1241 g DM / day). However, we found no effect of parasite burden upon intake rate or selection patterns. The results of a power analysis imply that any reduction in intake rate was less than 30%, which is less than the 30%–60% reduction in intake rate recorded for domestic sheep under moderate parasite burdens. This suggests that Soay sheep are more resilient to parasitism than domestic breeds. Despite evidence to the contrary from simple farm-based studies, the lack of any effect on selection patterns in this case suggests that parasites do not cause significant alterations to the selection patterns of herbivores in complex non-agricultural environments.
Isotopic reconstruction of marine food webs using cephalopod beaks: new insight from captively raised Sepia officinalis
Authors: Hobson K.A. , Cherel Y. 
Published: August 2006

Cephalopod beaks are a valuable source of material for stable isotope analysis to reconstruct the feeding ecology of cephalopods and their predators. We conducted a controlled captive-rearing experiment on the cuttlefish Sepia officinalis L., 1758 to 10 months of age. During the first and second months of life, animals were fed mysids ( Mysidopsis sp.) and shrimp ( Palaemonetes pugio Holthuis, 1949), but after 2 months, they were fed a homogeneous diet of shrimp ( Farfantepenaeus aztecus (Ives, 1891) and Litopenaeus setiferus (L., 1767)) until sampling. Soft tissues such as buccal mass, arm, and mantle were enriched in 15N over the shrimp diet by about 3.3‰, with little change in 13C, a result in keeping with previous findings for other marine predators. However, beaks showed little isotopic enrichment over the diets at the time of beak formation, with the beak rostral tips representing the neonatal diet and the remaining beak material representing the adult (shrimp) diet. Additionally, for four wild cephalopod species ( Todaropsis eblanae (Ball, 1841), Illex coindetii (Verany, 1839), Loligo vulgaris (Lamarck, 1798), and S. officinalis) obtained commercially in France, we measured δ13C and δ15N values in lower beaks and soft tissues. Similar to the results of our captive study, soft tissues were consistently enriched in 15N over beaks by an average of 4.8‰ (range 3.9‰–6.1‰) but were slightly depleted in 13C by 0.8‰ (0.7‰–1.2‰). The isotopic measurement of cephalopod beaks can thus be used to directly trace the isotopic composition of cephalopod diets and will be a powerful tool in the reconstruction of higher-trophic-level predators of cephalopods, since beaks are often the only material remaining for analysis from field samples.
Ontogenetic and interspecific variation in timing of movement and responses to climatic factors during migrations by pond-breeding amphibians
Authors: Todd Brian D. , Winne Christopher T. 
Published: August 2006

Pond-breeding amphibians from temperate regions undertake overland migrations to reproduce in aquatic habitats. In turn, their offspring metamorphose and emigrate to upland, terrestrial habitats. We examined the diel patterns and daily variability of migrations of adult and juvenile amphibians in response to climatic cues. Of the eight species ( Ambystoma talpoideum (Holbrook, 1838), Ambystoma tigrinum (Green, 1825), Bufo terrestris (Bonnaterre, 1789), Hyla gratiosa LeConte, 1856, Pseudacris crucifer (Wied-Neuwid, 1838), Pseudacris ornata (Holbrook, 1836), Rana sphenocephala Cope, 1886, and Scaphiopus holbrookii (Harlan, 1935)) that we observed, all migrated almost exclusively at night except for the recently metamorphosed B. terrestris, which frequently migrated diurnally (>50% of captures). Additionally, we correlated daily captures of adult and juvenile A. talpoideum, A. tigrinum, B. terrestris, and R. sphenocephala to maximum and minimum daily temperatures, number of previous days without rain, total rainfall during the previous 24 h, and interactions of these variables. Rain was often the most important predictor of amphibian movements. However, species differed in their response to climatic factors, with some species and age classes being more dependent on rain for migrations than others. Rapid changes in regional weather patterns may affect species’ migrations differently, possibly altering arrival times of reproductive adults or affecting the likelihood of successful migrations.
Consequences of forest fragmentation for juvenile survival in spotted (Ambystoma maculatum) and marbled (Ambystoma opacum) salamanders
Authors: Rothermel B.B. , Semlitsch R.D. 
Published: August 2006

We compared demographic traits of postmetamorphic salamanders among old fields, forest interior, and edge habitats over 2 years. Recently metamorphosed spotted salamanders ( Ambystoma maculatum (Shaw, 1802)) and marbled salamanders ( Ambystoma opacum (Gravenhorst, 1807)) were individually marked, added to terrestrial enclosures, and recaptured in pitfall traps. Proportion known alive in the fields was <5% by the first fall and declined to 0% for both species in the 2nd year. In forested enclosures, significantly more A. opacum (mean 38.5%) and A. maculatum (mean 16.7%) survived until the first fall and several individuals of each species attained sexual maturity. Mean proportion known alive was approximately two times higher in A. opacum than in A. maculatum, perhaps because of an advantage of earlier metamorphosis in A. opacum. Our results indicate that the first few months in the terrestrial environment is a critical period which determines survival between metamorphosis and first reproduction. Juveniles that weighed more initially had greater chances of surviving this period. We found no evidence that proximity to forest edges incurred fitness costs in terms of reduced growth or survival for juvenile ambystomatids. Because no juveniles survived to maturity in fields, breeding sites surrounded by non-forested habitat may be population sinks for these species.
Influence of temperature on maternity roost selection by noctule bats (Nyctalus noctula) and Leisler’s bats (N. leisleri) in Białowieża Primeval Forest, Poland
Authors: Ruczyński Ireneusz 
Published: August 2006

This study tests whether the temperature of tree cavities determines their selection by bats in Białowieża Primeval Forest (BPF), eastern Poland. Using a data logger, I simultaneously measured the temperature in cavities selected by bats as roosts and the temperature in available but unselected cavities. The maternity roosts chosen by noctule bats, Nyctalus noctula (Schreber, 1774), and Leisler’s bats, N. leisleri (Kuhl, 1817), during late pregnancy and lactation were warmer than unoccupied cavities, but temperature ranges in the two types of cavity did not differ. A logistic regression model showed that the mean cavity temperature during the night (2200–0400) and the minimum cavity temperature over a 24 h period were crucial for roost selection. This suggests that female noctule and Leisler’s bats selected roosts that promoted juvenile growth and used tree cavities that could save them energy while they were active because the cavity temperatures were close to the lower critical temperature of their thermoneutral zone. I also suggest that selection of warmer cavities minimized the bats' energy expenditure prior to emergence from the roost and that passive rewarming inside the cavity was an important factor in minimizing energetic costs of roosting by bats in BPF. Mean and maximum temperatures recorded near tree trunks increased with the height at which the temperature was measured (ground level, 10, 20, and 30 m), suggesting that bats can gain thermal benefits from insolation of the trunk by selecting highly placed cavities, as was observed in BPF.
Effect of soil type on burrowing behavior and cocoon formation in the green-striped burrowing frog,Cyclorana alboguttata
Authors: Booth D.T. 
Published: August 2006

This study examined the effect of soil type on burrowing behaviour and cocoon formation during aestivation in the green-striped burrowing frog, Cyclorana alboguttata (Günther, 1867). Given a choice, frogs always chose to burrow in wet sand in preference to wet clay. Frogs buried themselves faster and dug deeper burrows in sandy soil. However, under my laboratory conditions, there was little difference in the pattern of soil drying between the two soil types. Frogs in both sand and clay soil experienced hydrating conditions for the first 3 months and dehydrating conditions for the last 3 months of the 6-month aestivation period, and cocoons were not formed until after 3 months of aestivation. After 6 months, there were more layers in the cocoons of frogs aestivating in sand than those aestivating in clay. Frogs were able to absorb water from sandy soil with water potentials greater than –400 kPa, but lost water when placed on sand with a water potential of –1000 kPa.
Singing in the shade: song and song posts of northern cardinals near nesting Cooper’s hawks
Authors: Duncan William J. , Bednekoff Peter A. 
Published: August 2006

Animals may compensate for increased predation risk by changing the behaviours that make them vulnerable. In this study, we compared the singing and perching behaviours of northern cardinals ( Cardinalis cardinalis L., 1758) living within 100 m of nesting Cooper’s hawks ( Accipiter cooperii (Bonaparte, 1828)) with that of cardinals in similar control sites. Cardinals sang similar amounts at hawk nests and at control sites, but they sang from less exposed perches when near Cooper’s hawk nests. These results suggest that singing from an exposed perch is both more dangerous and more effective for northern cardinals.
Orientation-cage experiments with the European Quail during the breeding season and autumn migration
Authors: Rodríguez-Teijeiro J.D. , Barroso A. , Gallego S. , Puigcerver M. , Vinyoles D. 
Published: August 2006

The directional movements of the male European Quail, Coturnix coturnix (L., 1758), during the breeding season and autumn migration were studied using Emlen orientation cages. The characteristics and evolution of the habitat in which males were captured and the sexual behaviour shown at capture indicate that these birds move in search of mating partners rather than of suitable habitats. These displacements are known as “gypsy movements” but are better described, as argued in this paper, as “movements in search of females”. A majority of caged birds (59%) showed a preferred direction (α = 238.5°), which coincided almost exactly with that observed in recoveries of ringed birds during autumn migration (α = 251.3°) but not with results from cage experiments during the same migratory period (α = 187.8°). Therefore, we conclude that displacements of the male European Quail, as shown in ringing recoveries, are much more influenced by “movements in search of females” than by migration. These movements are clearly towards the southwest, the males taking short flights towards suitable breeding grounds and driven by river-course habitats. In addition, we confirm that Emlen funnels are suitable for controlled experiments on the orientation of males in demes of European Quail.
Effect of exposure to short-term heat stress on survival and fecundity in Drosophila ananassae
Authors: Sisodia Seema , Singh Bashisth N. 
Published: August 2006

In ectothermic organisms, temperature plays a vital role in survival and reproductive success. Founding isofemale lines from wild-collected females is a basic tool for characterizing quantitative traits in a natural population. The effects of heat shock, i.e., short exposure to heat stress, on survival and reproductive success in 10 recently collected isofemale lines of Drosophila ananassae Doleschall, 1858 were compared. Flies were treated as follows: (i) unstressed control; (ii) placed at 37 °C for 90 min (pre-treatment); (iii) placed at 40 °C for 60 min 24 h before the fecundity test; and (iv) placed at 40 °C for 60 min with pre-treatment 16 h before they were exposed to 40 °C. The heat stress strongly affected survival. However, there was no significant difference between the survival of males and females. Furthermore, the female fecundity, measured as F1 offspring produced over the next 12 days, was also reduced. Heat pre-treatment improved survival of both male and female and also improved female productivity. We found significant variation in female fecundity among isofemale lines, and intraclass correlations increased for stress treatments. The results suggest that a small increase in environmental stress may affect fitness traits, and there is enough genetic variation for thermal adaptation in D. ananassae.
FORWARD-RATE VOLATILITIES AND THE SWAPTION MATRIX: WHY NEITHER TIME-HOMOGENEITY NOR TIME-DEPENDENCE ARE ENOUGH
Authors: REBONATO RICCARDO 
Published: August 2006

This work presents the first systematic analysis of the whole swaption matrix by fitting a parsimonious, nonlinear, financially-inspired volatility model to market data. The study uses several years of data spanning period of major market volatility. We find that the quality of the fits is good (on average of the same magnitude as the bid-offer spread), and better when a displaced-diffusion approach is chosen, but some systematic shortcomings are observed and discussed. The analysis suggests that a two-regime Markov chain approach may be more successful and better financially motivated. More generally, the present study highlights the shortcomings of purely time-dependent or time-homogenous approaches. These findings should be applicable to other option markets as well. Finally, we find that the present (nonlinear) model vastly outperforms PCA-based approaches when in comes to predicting moves in implied volatilities.
LKB1/STK11 Suppresses Cyclooxygenase-2 Induction and Cellular Invasion through PEA3 in Lung Cancer
Authors: Upadhyay Sunil , Liu Chunyan , Chatterjee Aditi , Hoque Mohammad O. , Kim Myoung Sook , Engles James , Westra William , Trink Barry , Ratovitski Edward , Sidransky David 
Published: August 2006

Abstract
We showed that the PEA3 transcriptional factor interacted with LKB1, a serine/threonine kinase, which is somatically mutated in lung cancer. This interaction occurred through the ETS domain of PEA3 and the kinase domain of LKB1. Mutation of LKB1 in lung cancer cells stabilized PEA3. Reintroduction of wild-type (WT) LKB1 into cells induced down-regulation of PEA3 and subsequently resulted in reduced cyclooxygenase-2 RNA and protein expression, whereas germ-line and somatic LKB1 mutants were defective in this activity. LKB1 phosphorylated PEA3 and promoted its degradation through a proteasome-mediated mechanism. Cells expressing mutant LKB1 possessed greater invasive potential compared with cells expressing WT LKB1. Increased invasion of cells with mutant LKB1 was partly due to PEA3 expression, as RNA interference inhibition of PEA3 resulted in dramatic decrease of Matrigel invasion. However, forced expression of PEA3 resulted in down-regulation of epithelial markers and induction of mesenchymal markers. These results suggest that PEA3 stabilization due to LKB1 inactivation could lead to epithelial/mesenchymal transition and greater lung cancer invasion potential. (Cancer Res 2006; 66(16): 7870-9)
Met, the Hepatocyte Growth Factor Receptor, Localizes to the Nucleus in Cells at Low Density
Authors: Pozner-Moulis Sharon , Pappas Derek J. , Rimm David L. 
Published: August 2006

Abstract
Some breast cancer cases in our previous immunohistochemical studies show Met expression in the nucleus. Given nuclear localization of other receptor tyrosine kinases, we proceeded to investigate Met. Nuclear Met is seen in numerous cell lines and in germinal regions of many tissues using four unique antibodies. Cell fractionation reveals a 60-kDa band recognized by COOH-terminal Met antibodies that is present independent of hepatocyte growth factor treatment. Green fluorescent protein (GFP) fusion proteins of the cytoplasmic domain of Met transfected into HEK293 cells are found in the nucleus whereas the full-length Met-GFP fusion is membranous. Further deletions of the Met-GFP fusions identify a region of the juxtamembrane domain required for nuclear translocation. In a CaCo2 cell line model for epithelial maturation, we find that Met is initially nuclear, and then becomes membranous, after confluence. This work suggests processing of the Met receptor, analogous to ErbB4, resulting in the release of the cytoplasmic domain and its translocation to the nucleus in cells at low density. (Cancer Res 2006; 66(16): 7976-82)