bluuebunny/crossref_metadata_2025 huggingface dataset:
Distribution and increment of biomass in adjacent young Douglas-fir stands with different early growth rates
Authors: Espinosa Bancalari Miguel A. , Perry David A.
Published: April 2008

Total biomass increments were determined for three adjacent 22-year-old Douglas-fir (Pseudotsugamenziesii (Mirb.) Franco) plantations in the Oregon Coast Range that had widely different early growth rates. Estimated total aboveground biomass of the stands, designated slow, intermediate, and fast, was 98.7, 148.7, and 203.7 Mg•ha−1, respectively; estimated mean biomass increment in the 5 years previous to sampling was 8.9, 12.6, and 12.3 Mg•ha−1•year−1. The slow stand had a greater proportion of aboveground biomass in branches and a smaller proportion in stem wood than the intermediate and fast stands. Differences in biomass increment were primarily due to stem rather than crown growth. Total below ground biomass was highest in the fast stand, the difference being due to roots >5 mm in diameter; weight of roots <5 mm was greater in the slow and intermediate stands. Roots >5 mm comprised about 77% of the total root system in those stands and 90% in the fast stand. Increment of roots >5 mm was 2.2, 2.5, and 3.0 Mg•ha−1•year−1 in the slow, intermediate, and fast stands. The ratio of productivity to total leaf nitrogen suggests that nitrogen is a principal limiting resource in the intermediate stand. The fast stand, with a leaf area index 50% greater than the others, is probably limited by light. The slow stand has anaerobic soils during at least part of the year, which may restrict rooting depth and thereby induce water stress during summer drought.
Effect of timber harvesting on extractable nutrients in a northern Rocky Mountain forest soil
Authors: Entry James A. , Stark Nellie M. , Loewenstein Howard
Published: April 2008

Extractable nutrients were measured for 2 years in the organic horizon of a forest soil from a Rocky Mountain site subjected to four harvesting treatments (clear-cut and residue left, clear-cut and residue removed, clear-cut and residue burned, uncut control). Concentrations of extractable P, Ca, K, and Mg were significantly lower in winter than in spring, fall, or summer in all treatments except the clear-cut with residue left; decomposition rates of lodgepole pine (Pinuscontorta var. latifolia Engelm.) needles also were significantly higher in this than in any of the other treatments. Concentrations of extractable B, Cu, Fe, Mn, Na, Si, Zn, and total N did not differ significantly regardless of treatment or season, nor did concentrations of nutrients leached through the organic horizon, which suggests that litter acts as a nutrient sink, retaining nutrients on the cation exchange and releasing them slowly. Managers should leave as much organic residue as possible on harvested sites where soil nutrients are suspected of limiting tree growth to ensure adequate nutrition and moisture for conifer regeneration.
Variation in the PGI/AAT linkage group between populations of black spruce
Authors: Barrett J. W. , Cheliak W. M. , Knowles P. H.
Published: April 2008

Linkage analysis, using megagametophytes from a clonal seed orchard of black spruce (Piceamariana (Mill.) B.S.P.) detected a tight association between Pgi-2 and Aat-1 with a recombination frequency of 2.6%. This is in marked contrast to earlier estimates for this species, which were much greater. The present results suggest that black spruce may be comparable with numerous other conifer species demonstrating this particular, highly conserved association.
Beech bark disease: the temporal pattern of cankering in aftermath forests of Maine
Authors: Houston David R. , Valentine Harry T.
Published: April 2008

In North America, beech bark disease occurs when bark of American beech (Fagusgrandifolia) is infested by beech scale (Cryptococcusfagisuga), then infected and killed by a fungus, Nectriacoccinea var. faginata, Nectriagalligena, or both. In long-affected stands, internal defect results as trees are cankered over time. The amount of defect, patterns of defect development, and the relationship of climate to these patterns were studied in 50 trees from two stands in eastern Maine. Two cross sections from each of five 1 m long bolts from each tree were selected at random by importance sampling. The total area of canker on the outside surface of each growth sheath of each bolt was estimated from the arc lengths of cankers on the annual rings of the sampled cross sections. Cankering began in stems 12–37 years old and 2–11 cm diameter. Rates of cankering increased over time; years of high or low cankering were synchronous between trees and stands. Cankering in year N + 1 was negatively correlated (R2 = 0.803) with October rainfall in year N and number of severely cold days from December in year N–1 through March in year N. Presumably, these factors adversely affect the survival and establishment of the beech scale and perhaps the development of and infection by Nectria spp. Mild winters and dry autumns since 1983 may have permitted the marked increases in beech scale and bark cankering observed in study plots throughout the range of beech bark disease.
Reproductive growth and development in seven provenances of lodgepole pine
Authors: O'Reilly Conor , Owens John N.
Published: April 2008

Reproductive growth and development were studied in 1983 in seven provenances of Pinuscontorta Dougl. ssp. latifolia Engelm. growing in a provenance trial near Prince George, B.C. Stages of pollen release and seed-cone receptivity were scored by indices of cone development. Pollen- and seed-cone numbers were estimated and the distribution of seed cones within the upper crown and on annual growth increments of fourth-whorl branches was assessed. Pollen-and seed-cone bud development was followed in sectioned long-shoot buds taken at 2- to 3-week intervals. The times of maximum seed-cone receptivity and pollen release differed slightly among provenances, indicating that there was a high chance of cross-pollination. Differences among provenances in pollen-cone numbers were large, but smaller differences in seed-cone numbers were noted. No mature pollen cones or developing pollen-cone buds were found in the Yukon provenance. Seed-cone production varied with whorl position and was influenced by polycyclic long-shoot development. Potential pollen-cone buds were initiated from May until late June. Pollen cones first differentiated in early to mid July in all provenances. Potential seed-cone apices were noted from mid-June to late July and differentiation occurred in mid-July to early August, depending on provenance. Seed-cone bud development began first in the northern provenances.
Litter decomposition in southern Appalachian black locust and pine–hardwood stands: litter quality and nitrogen dynamics
Authors: White David L. , Haines Bruce L. , Boring Lindsay R.
Published: April 2008

To compare litter decomposition and nitrogen (N) dynamics in 16-year-old black locust and pine-hardwood forest stands, weight loss, N concentration, and litter quality of the dominant species in each stand were monitored for 863 days, using litterbags. The species studied were Robiniapseudo-acacia L. (leaflets and rachises), Liriodendrontulipifera L., and Rubus spp. (leaves and stems) in the black locust stand and Kalmialatifolia L., Pinusrigida Mill., and L. tulipifera in the pine-hardwood stand. Between-stand comparison of L. tulipifera leaf litter indicated a significant stand effect on weight loss during the first 8 months but no significant stand effects on N concentration and net immobilization. Initial lignin content was highly correlated to percent weight remaining and net N immobilization after 331 and 863 days. All litter types exhibited an absolute increase in "lignin" that appeared to originate from the more soluble litter fraction. Robiniapseudo-acacia leaflets, P. rigida, K. latifolia, and Rubus stems decomposed slowly, but only the latter two species were in the net N immobilization phase at day 863. Rubus leaf litter decomposed rapidly, releasing 70% of its original N by day 331. The role of Rubus and other understory species in influencing organic matter and N accretion in these early successional systems is discussed. Robiniapseudo-acacia leaflets contained 81% of their original N at day 863. This retention of N, coupled with its greater potential to form recalcitrant material during decomposition, suggests a mechanism to explain the long-term effects of Robiniapseudo-acacia on N storage in the forest floor and soil.
Asymbiotic nitrogen fixation in litter from Pacific Northwest forests
Authors: Heath B. , Sollins P. , Perry D.A. , Cromack Jr. K.
Published: April 2008

Asymbiotic nitrogen fixation in litter was assayed by acetylene reduction across a range of 25 forested sites in the Willamette Valley and Oregon Cascade and Coast ranges and periodically over a year at two Douglas-fir (Pseudotsugamenziesii (Mirb.) Franco) plantations in the Willamette Valley. Laboratory experiments showed that optimal conditions for N fixation by Douglas-fir litter were 200% moisture content and 22 °C. Annual fixation was 1.08 ± 0.13 kg/ha at one Willamette Valley plantation, 0.39 ± 0.06 kg/ha at the other. Fixation rates at the other 23 sites, which were sampled less frequently, ranged from 0 to 5 g N ha−1 day−1 and exceeded trace levels at only six sites, indicating annual totals much less than those at the Willamette Valley plantations. At four coastal and valley sites sampled by litter layer, older L layer Douglas-fir litter fixed the most N per gram dry weight. Percent N, percent C, and the C:N ratio of that litter layer did not differ significantly among sites or correlate with N-fixation rates. Forest-floor litter in most Northwest forests fixes no more than trace amounts of N, at most ~1 kg N ha−1 year−1. These amounts are smaller than N input from precipitation.
Diploid and haploid embryogenesis in Larixleptolepis, L. decidua, and their reciprocal hybrids
Authors: Aderkas P. von , Klimaszewska K. , Bonga J. M.
Published: April 2008

Diploid and haploid embryogenesis was induced in two Larix species (L. decidua and L. leptolepis) and their reciprocal hybrids. Diploid embryogenic tissue was initiated in immature zygotic embryos isolated with the micropylar half of the megagametophyte left attached. These were placed either on modified LM or MSG medium supplemented with the growth regulators 2,4-D and 6-benzyladenine. MSG medium was solidified with either gellan gum or agar. There was no appreciable difference in response between the two. Haploid embryogenesis was induced in isolated megagametophytes placed on modified LM medium supplemented with 2,4-D and 6-benzyladenine. Diploid embryogenic tissue was subcultured on medium with growth regulators, but haploid embryogenic tissue grew well on medium without growth regulators. There were few morphological differences between the diploid and haploid embryogenic tissue. In all species and hybrids, haploid cultures contained more coenocytic long cells. Binucleate cells were most common, but tetranucleate and octanucleate cells were also present. Haploid cultures showed poorer organization than the diploid ones, with only a few cultures having well-developed embryoids. Haploid tissue originated from expanded cells of the megagametophyte. Diploid tissue originated from the suspensor region of the zygotic embryo; it proliferated from isolated clusters of meristematic cells in early embryoids. Diploid and haploid cultures differed not only from the outset, but also in the mature embryoids they produced.
Comparing the lactate and EMG thresholds of recreational cyclists during incremental pedaling exercise
Authors: Candotti Cláudia Tarragô , Loss Jefferson Fagundes , Melo Mônica de Oliveira , La Torre Marcelo , Pasini Maicon , Dutra Lucas Araújo , de Oliveira José Leandro Nunes , de Oliveira Lino Pinto
Published: April 2008

The purpose of this study was to determine the validity of using the electromyography (EMG) signal as a noninvasive method of estimating the lactate threshold (LT) power output in recreational cyclists. Using an electromagnetic bicycle ergometer and constant pedaling cadence of 80 rpm, 24 recreational cyclists performed an incremental exercise protocol that consisted of stepwise increases in power output of 25 W every 3 min until exhaustion. The EMG signal was recorded from the right vastus lateralis (VL) and right rectus femoris (RF) throughout the test. Blood samples were taken from the fingertip every 3 min. The LT was determined by examining the relation between the lactate concentration and the power output using a log–log transformation model. The root mean square (RMS) value from the EMG signal was calculated for every 1-second non-superimposing window. Sets of pairs of straight regression lines were plotted and the corresponding determination coefficients (R2) were calculated. The intersection point of the pair of lines with the highest R2 product was chosen to represent the EMG threshold (EMGT). The results showed that the correlation coefficients (r) between EMGT and LT were significant (p < 0.01) and high for the VL (r = 0.826) and RF (r = 0.872). The RF and VL muscles showed similar behavior during the maximal incremental test and the EMGT and LT power output were equivalent for both muscles. The validity of using EMG to estimate the LT power output in recreational cyclists was confirmed.
Behavioural response of eastern wolves (Canis lycaon) to disturbance at homesites and its effects on pup survival
Authors: Argue A. M. , Mills K. J. , Patterson B. R.
Published: April 2008

Human disturbance at wolf dens and rendezvous sites (homesites) may have direct effects on pup survival and could result in the alteration of homesite-use characteristics. During a demographic study of eastern wolves ( Canis lycaon ) in Algonquin Provincial Park, Ontario, we entered active homesites to tag pups with VHF radio transmitters. Homesite attendance and pup survival data collected in 2003–2005 were used to determine (i) the immediate response of wolves to disturbance at homesites, (ii) whether distance moved between homesites was influenced by disturbance, (iii) if pup survival was compromised by researcher disturbance, and (iv) whether reuse in subsequent years differed between disturbed and undisturbed den sites. Packs tended to relocate pups after a disturbance, though we did not detect a difference in distances travelled between natural homesite shifts and those following disturbance. Disturbed homesites were reused in following years at a similar frequency as undisturbed homesites (6 of 15 vs. 8 of 22 homesites, respectively). Although postcapture mortality risk was slightly elevated for pups, we could not detect long-term effects of disturbance. This resilience to disturbance, and our documentation of effective techniques for radio-tagging young pups, demonstrate that research on wolf pup demography can be performed effectively without causing unacceptable negative impacts on wolf behaviour or mortality.
Partitioning of locomotor and feeding metabolism in sablefish (Anoplopoma fimbria)
Authors: Furnell Donald J.
Published: April 2008

The swimming, feeding, and standard metabolic rates of the sablefish (Anoplopoma fimbria) were determined using tunnel and mass respirometers. Swimming metabolic rate was measured for fish in both digestive and nondigestive states. Comparison of power–performance curves for fed and starved states suggested that sablefish were able to allocate oxygen supply preferentially to locomotor muscles and suppress the oxygen demand of digestion when active. Reduced blood flow to the stomach, liver, and spleen during exercise has been observed in other species and may provide a physiological mechanism to explain the results obtained with sablefish.
Effect of petroleum hydrocarbons on Atlantic cod, Gadus morhua, following chronic exposure
Authors: Kiceniuk J. W. , Khan R. A.
Published: April 2008

Experiments were conducted to ascertain the effects of crude oils at low concentrations on Atlantic cod (Gadus morhua) following long-term exposure (3–21 weeks) in a flow-through seawater system. Control and oil-treated fish were fed to satiation. Effects were assessed by comparing condition factor, organ indices, and hematological values with those of corresponding control animals. No mortality occurred but food consumption was significantly reduced in oil-treated cod, especially during summer–autumn. Condition factor and somatic indices of some organs were lower in oil-treated fish. Gall bladders were enlarged in oil-treated fish. Effects of oil exposure were less pronounced during winter, as food intake in both groups of fish was reduced considerably. The rate of gametogenesis was slower in male cod exposed to oil fractions in summer–autumn whereas spermeation was delayed in fish treated in winter–spring. These studies provide evidence that feeding, growth, and reproduction in male cod are biologically important variables that are affected following chronic exposure to petroleum.
Feeding chronology and daily ration calculations for winter flounder (Pseudopleuronectes americanus), American plaice (Hippoglossoides platessoides), and ocean pout (Macrozoarces americanus) in Passamaquoddy Bay, New Brunswick
Authors: Macdonald J. Stevenson , Waiwood Kenneth G.
Published: April 2008

Feeding chronologies of three species of cohabiting benthic fish, winter flounder (Pseudopleuronectes americanus), ocean pout (Macrozoarces americanus), and American plaice (Hippoglossoides platessoides), are described. The volume of food eaten by each species at each of four collection times over 24 h was analysed using analysis of covariance (ANCOVA), with fish length as the covariate. Daily ration was estimated using a gastric evacuation model, incorporating mean stomach volumes at four subdaily intervals and independent evacuation rates for slower (bivalves) and faster digested prey (amphipods and polychaetes). Winter flounder, American plaice, and ocean pout were daylight feeders with American plaice feeding more heavily later in the day. Winter flounder had the highest consumption rate (1.77% body weight/day) followed by ocean pout (1.68%) and American plaice (1.28%). Estimates of daily and subdaily food consumption were compared with corresponding estimates based on prey-specific state of digestion indices. This study indicates that estimating total and individual prey consumption at subdaily intervals provides a useful tool in determining feeding chronology and draws attention to potential biases encountered when more traditional analyses are used.
The effects of habitat density and the spatial distribution of food on the social behaviour of captive wintering American Tree Sparrows
Authors: Prescott David R. C.
Published: April 2008

Two artificial habitats containing 15% (low density) and 40% (high density) coniferous ground cover, and three feeding patterns representing different levels of spatial food distribution were used to investigate the effects of factors influencing individual spacing on the behaviour of captive, wintering American Tree Sparrows (Spizella arborea). Specifically, three aspects of social behaviour were examined: the frequency of agonistic encounters, the percentage of interactions initiated by dominants, and nearest-neighbour distances. Temperature effects were also considered. Interaction rates were lowest when food was most dispersed, and at higher temperatures. More interactions were recorded in the higher density habitat, as compared with the low density habitat, but the trend was reversed when food was highly dispersed. Nearest-neighbour distances decreased with increasing habitat density and food dispersion and were shortest in the high density habitat. Dominant birds initiated most encounters (70.7%), but less frequently when food was abundant or temperatures high, contradicting an assumption of previous models of optimal flock behaviour. It is suggested that these models, which rely on predicted changes in the allocation of available time by dominant birds to predict flock size, could be improved by considering the effects of habitat density and food dispersion, as well as differences in the social optimization strategies of different flocking species.
Reproduction by female Zapus princeps in relation to age, size, and body fat
Authors: Falk Jonathan W. , Millar John S.
Published: April 2008

Reproduction in female Zapus princeps, the western jumping mouse, was studied in relation to age, body size, and energy reserves in the form of fat content. Females were classified as reproductive if embryos, mammary tissue, or placental scars were present. Nonreproductive females were those showing no visible signs of pregnancy or lactation during midsummer, when breeding status could be determined with certainty. Only 9 of 22 (41%) 1-year-old females and 21 of 30 (70%) older females bred. Differences in size between breeders and nonbreeders were attributable to differences in age. Differences in fat content were attributed to size and breeding status, but could not be considered to reflect prebreeding condition. We speculate that the nonbreeding females were those in poor condition following hibernation. Most of these were yearlings.
Daily and diurnal variation of corneal thickness in pigmented rabbit
Authors: Ahmedbhai N. , Cullen A. P.
Published: April 2008

Central corneal thickness measurements were made on male pigmented rabbits using a custom-built digital Zeiss optical pachometer and double masked methods. Measurements were taken every hour for 24-h periods (while mimicking the animals' adapted light-dark cycle). During the dark cycle the corneal thickness increased by 10.33 ± 1.48% (SD) and 8.99 ± 2.10% (SD) for two 24-h cycles. In addition, measurements taken at 1000 each day showed that the daily fluctuation was ± 1% over the 30-day period.
Evolutionary relationships among Eimeria spp. (Apicomplexa) infecting cricetid rodents
Authors: Reduker David W. , Duszynski Donald W. , Yates Terry L.
Published: April 2008

Evolutionary relationships among seven species of Eimeria from five species of cricetid rodents (Neotoma albigula, Peromyscus eremicus, Peromyscus leucopus, Peromyscus maniculatus, Peromyscus truei) were examined by phenetic and cladistic analysis of oocyst structure, life-history data, and isozyme banding patterns. Phenetic and cladistic analyses revealed two distinct lineages of Eimeria spp.: type A Eimeria spp. (Eimeria albigulae, Eimeria arizonensis, Eimeria peromysci), characterized by subspheroid oocysts with rough outer walls, lemon-shaped sporocysts, oocyst residua, prominent Stieda bodies, and two obvious wall layers; and type B Eimeria spp. (Eimeria delicata, Eimeria lachrymalis, Eimeria ladronensis, Eimeria lange-barteli), characterized by ellipsoid oocysts with one obvious, smooth wall, no residuum, and ellipsoid or teardrop-shaped sporocysts with thin walls and tiny Stieda bodies. Cladistic analysis of the type A and type B data sets, using Eimeria nieschulzi and Eimeria papillata (hosts: Rattus norvegicus and Mus musculus, respectively) for outgroup comparison, showed the more derived nature of Eimeria spp. infecting Peromyscus spp. relative to those species infecting N. albigula. Comparison of parasite phylogenies to a hypothesized phylogeny for the hosts based on enzyme electrophoretic data revealed patterns of host–parasite phylogenetic congruence that were most evident at the generic level of the hosts.
Notes on the care of long-tail macaque (Macaca fascicularis) infants by stump-tail macaques (Macaca thibetana)
Authors: Burton Frances D. , Chan Leslie Kin Wai
Published: April 2008

An unusual but sustaining case of interspecific infant care behaviour was observed in June 1985 while an ecological and behavioural study of the macaques was being conducted in the forest of the Kowloon Peninsula, Hong Kong. We describe this specific interaction among three long-tail macaque infants (Macaca fascicularis) and their mothers and two stump-tail macaque (Macaca thibetana) females who acted as "babysitters." The cross-species infant care observed took place in a polyspecific group which also included rhesus monkeys (Macaca mulatta) and hybrids of rhesus and long-tail monkeys. This unique combination of macaque species in a large social and biological group provides an opportunity for the investigation of the role of behaviour in species identification and hybridization in natural habitats.
Mandibular dental anomalies of Northwest Atlantic harp seals, Phoca groenlandica
Authors: Stewart R. E. A. , Stewart B. E.
Published: April 2008

We examined 2267 harp seal mandibles to determine the frequency of extra, missing, and malformed teeth; to examine the effect of these anomalies on longevity; and to assess the usefulness of anomalies in identifying stocks of seals. Supernumerary teeth occurred in 1.7% of the seals, 0.5% of the seals were missing teeth (none because of trauma), and 0.6% had morphologically deviant teeth. Only 0.2% of the seals had more than one type of anomaly and none had all three. Average age and age–frequency distributions for anomalous and normal seals were not different. Anomalies were probably too rare and combined too much genetic variation to be useful in stock delineation.
Mineral hosts for gold and trace metals in regolith at Boddington gold deposit and Scuddles massive copper–zinc sulphide deposit, Western Australia: an LA-ICP-MS study
Authors: Le Gleuher Maïté , Anand Ravi R. , Eggleton Richard A. , Radford Nigel
Published: April 2008

The association between trace elements and saprolite minerals has been investigated at the Boddington gold deposit and Scuddles massive Cu-Zn sulphide deposit in Western Australia by
in situ
laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) and electron microprobe. The study provides new information about the occurrence and abundance of base metals, gold and their pathfinders in clay and ferruginous materials. Traces are predominantly located in vermiculite, interstratified clay minerals (chlorite–vermiculite and chlorite–smectite), goethite, hematite and titanium oxides. Although kaolinite is the main constitutent of saprolite, it retains insignificant amounts of trace elements and therefore dilutes geochemical anomalies. Anatase and rutile host abundant trace elements used as pathfinders for Au mineralization at Boddington (W, Bi and Mo) and base metal mineralization at Scuddles (Sb and Bi). As a result, the relative accumulation of these resistate minerals during weathering inflates pathfinder geochemical signatures. LA-ICP-MS compositional depth profiling obtained on conventional thin sections has proved to be an efficient tool to determine element–mineral associations in weathered material and to measure trace element concentrations. It allows a rapid detection of inclusions and highlights the distribution of trace elements between mineralogical phases.
The Emerging Functions and Mechanisms of Mammalian Fatty Acid–Binding Proteins
Authors: Storch Judith , Corsico Betina
Published: April 2008

Fatty acid–binding proteins (FABPs) are abundant intracellular proteins that bind long-chain fatty acids with high affinity. Nine separate mammalian FABPs have been identified, and their tertiary structures are highly conserved. The FABPs have unique tissue-specific distributions that have long suggested functional differences among them. In the last decade, considerable progress has been made in understanding the specific functions of the FABPs and, in some cases, their mechanisms of action at the molecular level. The FABPs appear to be involved in the extranuclear compartments of the cell by trafficking their ligands within the cytosol via interactions with organelle membranes and specific proteins. Several members of the FABP family have been shown to function directly in the regulation of cognate nuclear transcription factor activity via ligand-dependent translocation to the nucleus. This review will focus on these emerging functions and mechanisms of the FABPs, highlighting the unique functional properties of each as well as the similarities among them.
The class V myosin motor, myosin 5c, localizes to mature secretory vesicles and facilitates exocytosis in lacrimal acini
Authors: Marchelletta Ronald R. , Jacobs Damon T. , Schechter Joel E. , Cheney Richard E. , Hamm-Alvarez Sarah F.
Published: April 2008

We investigated the role of the actin-based myosin motor, myosin 5c (Myo5c) in vesicle transport in exocrine secretion. Lacrimal gland acinar cells (LGAC) are the major source for the regulated secretion of proteins from the lacrimal gland into the tear film. Confocal fluorescence and immunogold electron microscopy revealed that Myo5c was associated with secretory vesicles in primary rabbit LGAC. Upon stimulation of secretion with the muscarinic agonist, carbachol, Myo5c was also detected in association with actin-coated fusion intermediates. Adenovirus-mediated expression of green fluorescent protein (GFP) fused to the tail domain of Myo5c (Ad-GFP-Myo5c-tail) showed that this protein was localized to secretory vesicles. Furthermore, its expression induced a significant ( P ≤ 0.05) decrease in carbachol-stimulated release of two secretory vesicle content markers, secretory component and syncollin-GFP. Adenovirus-mediated expression of GFP appended to the full-length Myo5c (Ad-GFP-Myo5c-full) was used in parallel with adenovirus-mediated expression of GFP-Myo5c-tail in LGAC to compare various parameters of secretory vesicles labeled with either GFP-labeled protein in resting and stimulated LGAC. These studies revealed that the carbachol-stimulated increase in secretory vesicle diameter associated with compound fusion of secretory vesicles that was also exhibited by vesicles labeled with GFP-Myo5c-full was impaired in vesicles labeled with GFP-Myo5c-tail. A significant decrease in GFP labeling of actin-coated fusion intermediates was also seen in carbachol-stimulated LGAC transduced with GFP-Myo5c-tail relative to LGAC transduced with GFP-Myo5c-full. These results suggest that Myo5c participates in apical exocytosis of secretory vesicles.
Differential modulation of L-type calcium channel subunits by oleate
Authors: Tian Yingrao , Corkey Richard F. , Yaney Gordon C. , Goforth Paula B. , Satin Leslie S. , Moitoso de Vargas Lina
Published: April 2008

Nonesterified fatty acids such as oleate and palmitate acutely potentiate insulin secretion from pancreatic islets in a glucose-dependent manner. In addition, recent studies show that fatty acids elevate intracellular free Ca2+and increase voltage-gated Ca2+current in mouse β-cells, although the mechanisms involved are poorly understood. Here we utilized a heterologous system to express subunit-defined voltage-dependent L-type Ca2+channels (LTCC) and demonstrate that β-cell calcium may increase in part from an interaction between fatty acid and specific calcium channel subunits. Distinct functional LTCC were assembled in both COS-7 and HEK-293 cells by expressing either one of the EYFP-tagged L-type α1-subunits (β-cell Cav1.3 or lung Cav1.2) and ERFP-tagged islet β-subunits (iβ2aor iβ3). In COS-7 cells, elevations in intracellular Ca2+mediated by LTCC were enhanced by an oleate-BSA complex. To extend these findings, Ca2+current was measured in LTCC-expressing HEK-293 cells that revealed an increase in peak Ca2+current within 2 min after addition of the oleate complex, with maximal potentiation occurring at voltages <0 mV. Both Cav1.3 and Cav1.2 were modulated by oleate, and the presence of different auxiliary β-subunits resulted in differential augmentation. The potentiating effect of oleate on Cav1.2 was abolished by the pretreatment of cells with triacsin C, suggesting that long-chain CoA synthesis is necessary for Ca2+channel modulation. These results show for the first time that two L-type Ca2+channels expressed in β-cells (Cav1.3 and Cav1.2) appear to be targeted by nonesterified fatty acids. This effect may account in part for the acute potentiation of glucose-dependent insulin secretion by fatty acids.
Frontiers: Skeletal muscle sodium pump regulation: a translocation paradigm
Authors: Benziane Boubacar , Chibalin Alexander V.
Published: April 2008

The skeletal muscle sodium pump plays a major role in the removal of K+ions from the circulation postprandial, or after a physical activity bout, thereby preventing the development of hyperkalemia and fatigue. Insulin and muscle contractions stimulate Na+-K+-ATPase activity in skeletal muscle, at least partially via translocation of sodium pump units to the plasma membrane from intracellular stores. The molecular mechanism of this phenomenon is poorly understood. Due to the contradictory reports in the literature, the very existence of the translocation of Na+-K+-ATPase to the skeletal muscle cell surface is questionable. This review summarizes more than 30 years work on the skeletal muscle sodium pump translocation paradigm. Furthermore, the methodological caveats of major approaches to study the sodium pump translocation in skeletal muscle are discussed. An understanding of the molecular regulation of Na+-K+-ATPase in skeletal muscle will have important clinical implications for the understanding of the development of complications associated with the metabolic syndrome, such as cardiovascular diseases or increased muscle fatigue in diabetic patients.
Activation and inhibition of the micturition reflex by penile afferents in the cat
Authors: Woock John P. , Yoo Paul B. , Grill Warren M.
Published: April 2008

Coordination of the urinary bladder and the external urethral sphincter is controlled by descending projections from the pons and is also subject to modulation by segmental afferents. We quantified the effects on the micturition reflex of sensory inputs from genital afferents traveling in the penile component of the somatic pudendal nerve by electrical stimulation of the dorsal nerve of the penis (DNP) in α-chloralose anesthetized male cats. Depending on the frequency of stimulation (range, 1–40 Hz), activation of penile afferents either inhibited contractions of the bladder and promoted urine storage or activated the bladder and produced micturition. Stimulation of the DNP at 5–10 Hz inhibited distension-evoked contractions and increased the maximum bladder capacity before incontinence. Conversely, stimulation at 33 and 40 Hz augmented distension-evoked contractions. When the bladder was filled above a threshold volume (70% of the volume necessary for distension-evoked contractions), stimulation at 20–40 Hz activated de novo the micturition reflex and elicited detrusor contractions that increased voiding efficiency compared with distension-evoked voiding. Electrical stimulation of the DNP with a cuff electrode or percutaneous wire electrode produced similar results. The ability to evoke detrusor contractions by activation of the DNP was preserved following acute spinal cord transection. These results demonstrate a clear role of genital afferents in modulating the micturition reflex and suggest the DNP as a potential target for functional restoration of bladder control using electrical stimulation.
Proteomic analysis of the winter-protected phenotype of hibernating ground squirrel intestine
Authors: Martin Sandra L. , Epperson L. Elaine , Rose James C. , Kurtz Courtney C. , Ané Cécile , Carey Hannah V.
Published: April 2008

The intestine of hibernating ground squirrels is protected against damage by ischemia-reperfusion (I/R) injury. This resistance does not depend on the low body temperature of torpor; rather, it is exhibited during natural interbout arousals that periodically return hibernating animals to euthermia. Here we use fluorescence two-dimensional difference gel electrophoresis (DIGE) to identify protein spot differences in intestines of 13-lined ground squirrels in the sensitive and protected phases of the circannual hibernation cycle, comparing sham-treated control animals with those exposed to I/R. Protein spot differences distinguished the sham-treated summer and hibernating samples, as well as the response to I/R between summer and hibernating intestines. The majority of protein changes among these groups were attributed to a seasonal difference between summer and winter hibernators. Many of the protein spots that differed were unambiguously identified by high-pressure liquid chromatography followed by tandem mass spectrometry of their constituent peptides. Western blot analysis confirmed significant upregulation for three of the proteins, albumin, apolipoprotein A-I, and ubiquitin hydrolase L1, that were identified in the DIGE analysis as increased in sham-treated hibernating squirrels compared with sham-treated summer squirrels. This study identifies several candidate proteins that may contribute to hibernation-induced protection of the gut during natural torpor-arousal cycles and experimental I/R injury. It also reveals the importance of enterocyte maturation in defining the hibernating gut proteome and the role of changing cell populations for the differences between sham and I/R-treated summer animals.
Sympathetic input modulates, but does not determine, phase of peripheral circadian oscillators
Authors: Vujović Nina , Davidson Alec J. , Menaker Michael
Published: April 2008

The circadian clock in the suprachiasmatic nucleus (SCN) maintains phase synchrony among circadian oscillators throughout the organism. Environmental light signals entrain the SCN, but timed, limited meal access acts as an overriding time cue for several peripheral tissues. We present data from a peripheral oscillator, the submaxillary salivary gland, in which temporal restriction of meals fails to entrain gene expression. In day-fed rats, submaxillary gland rhythms in expression of the clock gene Period1 ( Per1) stay entrained to the light cycle (peaking at night) or become arrhythmic. This result suggests that feeding cues compete weakly with light cycle cues to set the phase of clock genes in this tissue. Since the submaxillary glands receive sympathetic innervation originating in the SCN, which relays light cycle cues to other oscillators, we attempted to assess the role of this neural input in phase control of submaxillary Per1 expression. We sympathetically denervated the submaxillary glands before subjecting rats to daytime-restricted feeding. After denervation, Per1 rhythms in all submaxillary glands shifted phase 180° and entrained to daytime feeding. These results support the hypothesis that peripheral oscillators may receive multiple signals contributing to their phase of entrainment. Sympathetic efferents from the SCN can relay light cycle information, while other external cues may reach tissues through other efferents or nonneural pathways. In an abnormal, disruptive regimen such as daytime-restricted feeding, these different signals compete. Arrhythmicity may result if one signal is not clearly dominant. Elimination of the dominant signal (e.g., surgical sympathectomy) may allow a secondary signal to control phase.
Chronic food shortage and seasonal modulations of daily torpor and locomotor activity in the grey mouse lemur (Microcebus murinus)
Authors: Giroud Sylvain , Blanc Stéphane , Aujard Fabienne , Bertrand Frédéric , Gilbert Caroline , Perret Martine
Published: April 2008

The extent to which seasonal plasticity in torpor displayed by one of the smallest Malagasy primates ( Microcebus murinus) will help survival in the context of ongoing global change-induced chronic food shortage, is unknown. Body temperature (Tb) and locomotor activity were measured by telemetry in short- (SD, winter-acclimated) and long-days (LD, summer-acclimated) males ( n = 24) during an experimental 35-day calorie restriction of 40 or 80%. Under SD exposure, regardless of calorie restriction intensity, mouse lemurs immediately increased torpor depth and duration by 4.6-fold, and showed greater phase-advanced entry into torpor (2.4-fold). Tb adjustments were efficient under 40% calorie restriction to maintain body mass, whereas they did not prevent a 0.71 ± 0.11 g/day mass loss during 80% calorie restriction. The 40% food-deprived LD animals combined an early shallow deepening of torpor (1°C) and a late 18% decrease in locomotor activity, resulting in a moderate 6% mass loss. After 15 days of 80% calorie restriction, LD animals exhibited a SD phenotype by increasing their torpor duration and phase-advancing the entry of torpor (16 min/day). Those adjustments had no impact on mass loss (0.93 ± 0.07 g/day) as locomotor activity increased four-fold. Daily torpor allows M. murinus to face moderate food shortage whatever the photoperiod but poorly mitigates energy imbalance during severe food deprivation, especially under LD exposure. Although the behavioral thermoregulation role warrants further investigation in energy savings, M. murinus survival would be impaired during long-term food shortage in summer.
Regression of glomerulosclerosis in subtotally nephrectomized rats: effects of monotherapy with losartan, spironolactone, and their combination
Authors: Piecha Grzegorz , Koleganova Nadezda , Gross Marie-Luise , Geldyyev Aman , Adamczak Marcin , Ritz Eberhard
Published: April 2008

Angiotensin II accelerates and renin-angiotensin system blockade halts progression; blockade with high doses even reverses established glomerulosclerosis. Aldosterone also accelerates progression of glomerulosclerosis, partially independently of angiotensin II. The purpose of this study was to assess the relative ability of an angiotensin receptor type 1 (AT1) blocker, a mineralocorticoid receptor blocker, and their combination to reverse glomerulosclerosis. Sprague-Dawley rats were subjected to subtotal renal ablation (SNX) or sham operation. Eight weeks after surgery, they were either euthanized or allocated to treatment with vehicle, losartan, spironolactone, their combination, or unspecific antihypertensive treatment (dihydralazine) for 4 wk. Renal morphology was evaluated by stereology in tissues obtained using pressure-controlled perfusion fixation. Systolic blood pressure was significantly higher in SNX compared with sham-operated animals and decreased in all treatment groups. Compared with wk 8 after SNX, the glomerulosclerosis index (GSI) had increased further by week 12 in the vehicle- and dihydralazine-treated groups but was significantly lowered in the SNX+losartan as well as in the SNX+losartan+spironolactone groups and had not progressed further in the SNX+spironolactone group. The study confirms the partial regression of established glomerulosclerosis in subtotally nephrectomized rats after high-dose AT1 receptor blockade. Nonhyperkalemic doses of spironolactone prevented the increase but failed to decrease the GSI below the 8-wk level and preserved podocyte numbers. Combining the AT1 blocker with mineralocorticoid receptor blockade failed to further increase the regression of glomerulosclerosis.
Sex differences in the perceived intensity of breathlessness during exercise with advancing age
Authors: Ofir Dror , Laveneziana Pierantonio , Webb Katherine A. , Lam Yuk-Miu , O'Donnell Denis E.
Published: April 2008

The prevalence of activity-related breathlessness increases with age, particularly in women, but the specific underlying mechanisms have not been studied. This novel cross-sectional study was undertaken to examine the effects of age and sex, and their interaction, on the perceptual and ventilatory responses to incremental treadmill exercise in 73 healthy participants (age range 40–80 yr old) with normal pulmonary function. Age-related changes at a standardized oxygen uptake (V̇o2) during exercise included significant increases in breathlessness ratings (Borg scale), ventilation (V̇e), ventilatory equivalent for carbon dioxide, and the ratio of tidal volume (Vt) to dynamic inspiratory capacity (IC) (all P < 0.05). These changes were quantitatively similar in women ( n = 39) and in men ( n = 34). For the group as a whole, exertional breathlessness ratings increased as resting static inspiratory muscle strength diminished ( P = 0.05), as exercise ventilation increased relative to capacity ( P = 0.013) and as the Vt/IC ratio increased ( P = 0.003) during exercise. Older women (60–80 yr old, n = 23) reported greater ( P < 0.05) intensity of exertional breathlessness at a standardized V̇o2 and V̇e than age-matched men ( n = 16), despite similar age-related changes in ventilatory demand and dynamic ventilatory mechanics. These increases in breathlessness ratings in older women disappeared when sex differences in baseline maximal ventilatory capacity were accounted for. In conclusion, although increased exertional breathlessness with advancing age is multifactorial, contributory factors included higher ventilatory requirements during exercise, progressive inspiratory muscle weakness, and restrictive mechanical constraints on Vt expansion related to reduced IC. The sensory consequences of this age-related respiratory impairment were more pronounced in women, who, by nature, have relatively reduced maximal ventilatory reserve.
ImagingGABAcReceptors with Ligand-Conjugated Quantum Dots
Authors: Tomlinson Ian D. , Gussin Hélène A. , Little Deborah M. , Warnement Michael R. , Qian Haohua , Pepperberg David R. , Rosenthal Sandra J.
Published: April 2008

We report a methodology for labeling theGABAcreceptor on the surface membrane of intact cells. This work builds upon our earlier work with serotonin-conjugated quantum dots and our studies with PEGylated quantum dots to reduce nonspecific binding. In the current approach, a PEGylated derivative of muscimol was synthesized and attached via an amide linkage to quantum dots coated in an amphiphilic polymer derivative of a modified polyacrylamide. These conjugates were used to imageGABACreceptors heterologously expressed in Xenopus laevis oocytes.
Using Nonuniform Fiber to Generate Slow Light via SBS
Authors: Li Wenhai , Bao Xiaoyi , Kalosha V. P. , Chen Liang , Li Ming-Jun
Published: April 2008

The data pulse delay based on slow light induced by stimulated Brillouin scattering (SBS) in a nonuniform dispersion decreasing fiber (DDF) is demonstrated experimentally, and the distortions of data pulses at different beat frequencies are studied. We found that a delay exceeding a pulse width can be achieved at particular beat frequency, and the DDF has larger delay versus gain slope coefficient with much better output pulse quality than single-mode fiber.
Effects of Subminimum Inhibitory Concentrations of Antibiotics on thePasteurella multocidaProteome: A Systems Approach
Authors: Nanduri Bindu , Lawrence Mark L. , Peddinti Divya Swetha , Burgess Shane C.
Published: April 2008

To identify key regulators of subminimum inhibitory concentration (sub-MIC) antibiotic response in thePasteurella multocidaproteome, we applied systems approaches. Using 2D-LC-ESI-MS2, we achieved 53% proteome coverage. To study the differential protein expression in response to sub-MIC antibiotics in the context of protein interaction networks, we inferredP. multocidaPm70 protein interaction network from orthologous proteins. We then overlaid the differential protein expression data onto theP. multocidaprotein interaction network to study the bacterial response. We identified proteins that could enhance antimicrobial activity. Overall compensatory response to antibiotics was characterized by altered expression of proteins involved in purine metabolism, stress response, and cell envelope permeability.
Particle Swarm Optimization for Multimodal Functions: A Clustering Approach
Authors: Passaro Alessandro , Starita Antonina
Published: April 2008

The particle swarm optimization (PSO) algorithm is designed to find a single optimal solution and needs some modifications to be able to locate multiple optima on a multimodal function. In parallel with evolutionary computation algorithms, these modifications can be grouped in the framework of niching. In this work, we present a new approach to niching in PSO based on clustering particles to identify niches. The neighborhood structure, on which particles rely for communication, is exploited together with the niche information to locate multiple optima in parallel. Our approach was implemented in thek‐means‐based PSO (kPSO), which employs the standardk‐means clustering algorithm, improved with a mechanism to adaptively identify the number of clusters.kPSO proved to be a competitive solution when compared with other existing algorithms, since it showed better performance on a benchmark set of multimodal functions.