bluuebunny/crossref_metadata_2025 huggingface dataset:
Clutch size and egg size of spruce grouse in relation to spring diet, food supply, and endogenous reserves
Authors: Naylor Brian J. , Bendell James F.
Published: February 2008

We examined the hypothesis that female spruce grouse (Dendragapus canadensis) rely entirely on their spring diet or endogenous reserves for the nutrients required for clutch formation. Spring food habits of 40 radio-tagged hens were documented by direct observation (21 262 min) during the period encompassing oviducal recrudescence, follicular development, and egg laying (late April – late May 1984 – 1986) and compared with clutch size and mean egg weight. Hens consumed conifer foliage, flowers, fruits, and foliage of ground plants, grit, and arthropods. Compared with their prebreeding diet, foods preferred in spring were rich in protein and P, but not necessarily Ca. Large clutch size was associated with a high rate of intake of the two most preferred foods, flowers of trailing arbutus (Epigaea repens) and spore capsules of Polytrichum mosses, and crude protein, P, and Ca, but was not related to the size of hens (body weight) or the size of endogenous reserves (scaled body weight). Egg size was not associated with spring diet or the size of endogenous reserves, but appeared to be related to the size of hens. Rate of intake of arbutus flowers and moss capsules was correlated with their availability on territories, suggesting that clutch size might have been proximately limited by food supply. However, rough estimates of nutrient intake suggested that the spring diet provided only about 60% of the protein and 45% of the Ca needed for clutch formation. Consequently, hens appeared to rely on both their spring diet and stored reserves for the nutrients required for clutch formation.
Remodeling processes during anterior regeneration of Owenia fusiformis (Polychaeta, Annelidae): a morphological and immunocytochemical survey
Authors: Coulon Josiane , Diano Monique , Arsanto Jean-Pierre , Thouveny Yves
Published: February 2008

Morphological and immunocytochemical studies were used to determine the correlations among cytoskeleton, junction complex, and basement membrane reorganization during anterior regeneration in Owenia fusiformis. Electron microscopical observations showed that, at the point of amputation, in conjunction with the disorganization of the extracellular matrix, alterations in the adhesive junctions caused dramatic changes in the distribution of intermediary filaments. Fluorescence microscopy investigations with fluorescein – phalloidin and antibodies to actin and Owenia tropomyosin visualized a basal actin network in epidermal cells, which was reorganized during regeneration. Two or three days after amputation, this cortical mat was not observed in blastema where the basal membrane was lacking. It was still incompletely reassembled after 4 or 5 days, i.e., when the thin reforming basal membrane, which stained with anti type IV collagen antibody, did not yet display collagen fibrils. In the epidermis of 6- to 7-day-old regenerates, the basal membrane, intercellular junctions, and actin and intermediary filament cytoskeletons exhibited nearly normal structural features. Use of antibody to Owenia paramyosin showed that the reorganization of the muscles during regeneration was concomitant with actin cytoskeletal reconstruction, as appeared after antitropomyosin labeling. Immunofluorescence findings were checked and (or) specified by immunogold staining.
Temperature in beaver lodges and bank dens in a near-boreal environment
Authors: Buech Richard R. , Rugg David J. , Miller Nancy L.
Published: February 2008

The thermal environment of selected lodges and bank dens of beavers (Castor canadensis) was studied in northeastern Minnesota to evaluate determinants of chamber air temperature. Mean air temperature was higher while the range in mean air temperature was smaller inside the chamber than outside in all months. Seasonal temperature extremes in lodges were generally within the thermoneutral zone of beavers year-round. Thus, shelters allow beavers to exploit environments that would otherwise be physiologically unsuitable to them. Data were consistent with our hypothesis that temperature of the soil or water substrate has a dominant influence on chamber air temperature. Two bank dens were cooler than an open-water lodge; hence onshore shelters may offer better protection against heat stress during hot weather. In winter, it appears that (i) total insulation (lodge walls plus snow) is sufficient to counter the influence of outside air temperature, (ii) temperature of the substrate underlying a lodge largely determines chamber air temperature, and (iii) heat produced by beavers raises the temperature of lodges above that derived from the lodge substrate.
Nest tree use by primary cavity-nesting birds in south central British Columbia
Authors: Harestad Alton S. , Keisker Dagmar G.
Published: February 2008

Heartwood decay was the most important factor in nest tree selection by primary cavity-nesting birds in the Interior Douglas-fir Biogeoclimatic Zone of British Columbia. Of 243 active nests, most were in trembling aspen (Populus tremuloides) and paper birch (Betula papyrifera). Douglas-fir (Pseudotsuga menziesii) and hybrid spruce (Picea engelmannii × glauca) were not used for nesting. Strong excavators (Yellow-bellied Sapsucker (Sphyrapicus varius), Pileated Woodpecker (Dryocopus pileatus), and Hairy Woodpecker (Picoides villosus)) preferred to nest in live trembling aspen with heartwood decay. Weak excavators (Red-breasted Nuthatch (Sitta canadensis), Northern Flicker (Colaptes auratus), and Downy Woodpecker (Picoides pubescens)) preferred to nest in dead trees or dead tops of live trees. Yellow-bellied Sapsucker preferred to nest in trees larger than 30 cm diameter at breast height, and Pileated Woodpecker preferred trees larger than 40 cm diameter at breast height. No significant preference for nest tree diameter was detected for other species.
Supercooling and freeze tolerance in hatchling painted turtles (Chrysemys picta)
Authors: Paukstis Gary L. , Shuman Robert D. , Janzen Fredric J.
Published: February 2008

Hatchling painted turtles, (Chrysemys picta) in north central Nebraska overwinter terrestrially within the nest cavity. Nest temperatures as low as −2.1 °C were recorded during January 1982 within nests from which hatchlings survived. Under laboratory conditions, nine turtles survived a cooling cycle (0 to −8.0 to 0 °C) over a 29-h period. Four of these turtles exhibited the ability to supercool to temperatures as low as −8.9 °C at which point freezing occurred. Partial freeze tolerance was exhibited by one individual. The ability of hatchling painted turtles to supercool and to survive subfreezing temperatures may be an important factor in the northern distribution of this species.
Flight speeds of the barn swallow, Hirundo rustica
Authors: Blake R. W. , Kolotylo R. , Cueva H. de la
Published: February 2008

A Doppler radar hand gun was used to measure flight speeds of barn swallows (Hirundo rustica) to determine whether mean flight speed coincides with either the minimum power, Vmp, or maximum range, Vmr, speeds predicted by aerodynamic theory. In addition, flight speeds are also compared with the maximum range speed, V′mr, when the mechanical equivalent of the standard metabolic rate is included in the power curve. A total of 821 speed recordings were divided into two groups based on observed flight behaviour. Group A had characteristically low (<0.5 m above the ground) and straight flight paths. Group B flew higher (>0.5 m) and erratically. Mean flight speeds of 8.6 and 6.8 m∙s−1 were determined for groups A and B, respectively. When compared separately, both means are significantly different from predicted values of Vmp (= 4.2 m∙s−1, p < 0.001), Vmr (= 5.6 m∙s−1, p < 0.001), and V′mr (= 6.2 m∙s−1, p < 0.001). It is likely that the birds fly at significantly higher speeds than the predicted optima for most routine flight activities. The penalties involved in departing from Vmp, Vmr, and V′mr (assessed as percent increase in total aerodynamic power relative to Vmp, Vmr, or V′mr) are substantial.
Histological and quantitative changes in the annual testicular cycle of Triturus marmoratus marmoratus
Authors: Saez Francisco Jose , Fraile Benito , Paniagua Ricardo
Published: February 2008

Eight male marbled newts (Triturus marmoratus marmoratus) were collected on the 15th of each month in 1987 and their testes were studied by light and electron microscopy. Quantitative studies also were performed to establish the annual testicular cycle and the total volume per testis occupied by each germ cell type throughout the year. Characteristic ultrastructural features of germ cells are the occurrence of a well-developed Golgi complex in primary spermatogonia; multiple small dictyosomes and nuclear blebs in primary spermatocytes; peripherally situated mitochondria; long strands of endoplasmic reticulum and subsurface cisternae in round spermatids; and abundant rough endoplasmic reticulum in follicular cells. Secondary spermatocytes have a short or absent interphase and are observed in the prophase. The annual testicular cycle comprises three periods: (i) germ cell proliferation (May–June), characterized by the formation of primary spermatocytes that undergo meiosis, giving rise to round spermatids; (ii) spermiogenesis (July–September), during which round spermatids develop into spermatozoa and the interstitial boundary cells are transformed into glandular tissue cells; and (iii) testicular quiescence (October–April) in which the testis contains only spermatozoa, glandular tissue, and a few primordial germ cells and spermatogonia. In the second phase of testicular quiescence (February–April) spermatozoa are released from the testis and proliferation of secondary spermatogonia occurs.
Comparison of energy metabolism in relation to daily activity and milk consumption by caribou and muskox neonates
Authors: Parker Katherine L. , White Robert G. , Gillingham Michael P. , Holleman Dan F.
Published: February 2008

Growth rates, milk intake, activity patterns, and daily energy expenditures of neonatal caribou (Rangifer tarandus granti) and muskoxen (Ovibos moschatus) were compared over a 100-day period to examine the strategies of two arctic follower species with different life history patterns. Relative growth rates, which reflected milk protein and energy intake, were higher for caribou during the 1st week of age and after 75 days of age than for muskox calves. Daily energy expenditures, estimated with the doubly labeled water technique, were significantly greater for caribou neonates than for muskoxen. Adult female caribou lost body weight during the first 2–3 weeks of lactation, but then increased 15% above postpartum weights during the summer period. Adult female muskoxen maintained weight, with no significant changes throughout the summer. Caribou milk was higher in protein, dry matter, and energy content than that of muskoxen.
Photoperiod synchronizes reproduction and growth in the southern flying squirrel,Glaucomys volans
Authors: Lee Theresa M. , Zucker Irving
Published: February 2008

Southern flying squirrels were housed in a simulated natural photoperiod for 40°N latitude and held at a constant temperature of 23 °C with food and water provided ad libitum. Body weight and reproductive condition were monitored weekly for 2 years. Males were in reproductive condition between January and mid-August and females were in estrus from late February to mid-April and again from mid-June until early August. Young were conceived during both estrous periods and several squirrels produced two litters in the same year. Minimum body weights were recorded in adults in mid-October each year. Pups born in the spring grew more rapidly than those from summer litters, and reached puberty at 2.5 months as compared with 6–8 months of age for the summer litters. Several seasonal rhythms appear to be controlled by photoperiod in this species.
Postmortem body temperatures in the minke whale, Balaenoptera acutorostrata
Authors: Vongraven Dag , Ekker Morten , Espelien Arild R. , Aarvik Frode J.
Published: February 2008

Postmortem temperature regimes were measured in 11 minke whales, Balaenoptera acutorostrata, at tissue depths varying from 1.5 (in the blubber) to 30 cm, at two different sites on the whales' sides, one in the flipper region (site A) and one in the dorsal fin region (site B). Body temperatures of instantaneously killed whales were assumed to represent those of living animals. Core body temperatures were 35.0 °C at site A and 35.6 °C at site B. Core body temperature and the size of the thermal core were affected by blubber thickness and the time between harpoon strike and death, but were not influenced by duration of pursuit prior to harpooning. Both intra- and inter-specific comparisons reveal that the thickness of the blubber layer is important for the maintenance of thermal gradients and, thereby, for heat conservation.
Allozymic and physiological variation in populations of sea urchins (Strongylocentrotus spp.)
Authors: Stickle William B. , Liu Li-Lian , Foltz David W.
Published: February 2008

Tolerance and activity coefficients (1000/righting time (s)) were determined in different salinity treatments for Strongylocentrotus droebachiensis (O. F. Muller, 1776) from a variable-salinity habitat north of Juneau, Alaska, and for S. droebachiensis and S. pallidus (G. O. Sars, 1871) from high-salinity habitats near Friday Harbor, Washington. The 28-day LC50 values of populations of S. droebachiensis from southeastern Alaska and Washington were similar (13‰ salinity) while that of S. pallidus was 21‰ salinity. Activity coefficients of S. droebachiensis indicate functional competence from 20 to 30‰ salinity; S. pallidus remains competent only at 30‰ salinity. For allozymic analysis, sea urchins (N = 820) were collected from five locations (three in Alaska and two in Washington). Two polymorphic allozyme loci (malate dehydrogenase-2 and phosphoglucose isomerase) were examined in all populations. The difference in allele frequencies between the species was highly significant (P < 0.0001) for Mdh-2 and nominally significant (P < 0.05) for Pgi. However, the species share the same alleles at both loci, and the allele frequency variance between the two species is low. Genotypic variation exists between the two species of sea urchins but not among populations of S. droebachiensis. Strongylocentrotus droebachiensis from Alaska and Washington are equally euryhaline with respect to tolerance but the brackish-water population is more active at 15‰ salinity.
Foraging characteristics of female northern fur seals (Callorhinus ursinus) and California sea lions (Zalophus californianus)
Authors: Antonelis George A. , Stewart Brent S. , Perryman Wayne F.
Published: February 2008

The foraging characteristics of northern fur seals (Callorhinus ursinus) and California sea lions (Zalophus californianus) from San Miguel Island, California, were studied during the 1985 summer breeding season. A radio transmitter was attached to 25 postpartum females of each species and used to determine their locations at sea and the frequency and duration of their feeding trips. Northern fur seals usually foraged in the oceanic zone where the mean water depth was 933 m (n = 12). California sea lions principally were found in the neritic zone, where water depth averaged 323 m (n = 9). Most fur seals (92%) were found northwest of San Miguel Island, whereas the sea lions were commonly found to the northwest (55%) or in areas south (22%) of the island. Although both species evidently foraged at similar distances from the island, foraging trips of fur seals [Formula: see text] were over twice as long as those of sea lions [Formula: see text]. Fur seals were ashore less time [Formula: see text] than were sea lions [Formula: see text] between foraging trips. Analysis of scats revealed that fur seals and sea lions ate similar prey (northern anchovy, Engraulis mordax; Pacific whiting, Merluccius productus; juvenile rockfish, Sebastes spp.; market squid, Loligo opalescens; and nail squid, Onychoteuthis borealijaponicas), although the relative proportions of these prey differed. Factors influencing the observed foraging characteristics probably were availability of prey and phylogenetic constraints associated with life-history traits of northern fur seals and California sea lions.
Effect of temperature and hydric conditions on blood pH in embryonic snapping turtles (Chelydra serpentina)
Authors: Birchard Geoffrey F. , Packard Mary J. , Packard Gary C.
Published: February 2008

The effect of temperature on blood pH in embryonic snapping turtles (Chelydra serpentina) was examined to determine whether the blood pH changes in the same manner as the neutral pH of pure water. Eggs were incubated on moistened vermiculite (water potential of −150 or −950 kPa) at 26 or 27 °C. On day 59 of incubation, eggs were placed in individual containers and assigned to incubators set at temperatures between 18.5 and 30 °C. Blood samples were taken on day 60 of incubation. Blood pH of the embryos varied in a manner similar to that observed in adults of this species: blood pH declined with increasing temperature, with a slope of −0.021 pH/°C. The decrease of blood pH with increasing temperature may be accomplished passively, with blood CO2 partial pressure increasing as a result of greater metabolic production of CO2 while the diffusive excretion of this gas remains relatively constant. No effect of substrate water potential on blood pH was observed.
Swimming velocities in otariids
Authors: Ponganis Paul J. , Ponganis Edward P. , Ponganis Katherine V. , Kooyman Gerald L. , Gentry Roger L. , Trillmich Fritz
Published: February 2008

Velocities during surface swimming and diving were measured with microprocessor recorders in four otariid species: northern fur seals (Callorhinus ursinus), Galapagos sea lions (Zalophus californianus wollebaeki), Galapagos fur seals (Arctocephalus galapagoensis), and Hooker's sea lions (Phocarctos hookeri). Mean surface swimming velocities ranged from 0.6 to 1.9 m/s. Transit distances to feeding sites (1.2–90 km) were calculated using these velocities. Dive velocities, recorded every 15 s, ranged from 0.9 to 1.9 m/s. These velocities were consistent with calculated minimal cost of transport velocities in the smaller species. Using time partitioning, the metabolic cost of a northern fur seal foraging trip is estimated on the basis of recorded velocities and their calculated energy costs. This value is within 6% of that previously made with doubly labeled water techniques.
Redescription of Eurycercus (Teretifrons) glacialis (Cladocera, Chydoridae), and description of a new species, E. (T.) nigracanthus, from Newfoundland, Canada
Authors: Hann B. J.
Published: February 2008

A redescription of Eurycercus (Teretifrons) glacialis Lilljeborg, 1901 is given, based solely on type material from Bering Island, Komandorski Islands (= Commander Islands), east of Kamchatka Peninsula, USSR. Eurycercus nigracanthus n.sp. is described from Newfoundland, and represents the most southerly known taxon in the subgenus Teretifrons. Although the subgenus is considered to be Holarctic in distribution, it is now seen that the range of E. glacialis is more restricted; in particular, at least one new species (and probably more) in the subgenus exists in North America.
Seasonal thyroid hormone levels of free-ranging white-tailed deer (Odocoileus virginianus) in Ontario
Authors: Hamr J. , Bubenik G. A.
Published: February 2008

Blood samples from killed and livetrapped deer of southern and central Ontario were analyzed for thyroxine (T4) and triiodothyronine (T3). Mean seasonal levels for six sex-age classes of deer ranged from 150 to 400 ng/dL (T3) and from 6.0 to 18.0 μg/dL (T4). Seasonal variation of T4 was less pronounced than that of T3. Both hormones decreased in the fall as compared with spring and summer, especially in yearling and older bucks. T3 values were also low in the winter but increased in spring and summer for most tested categories of deer. Differences in seasonal T3 and T4 concentrations were found between male and female deer older than 1 year, and among sex-age classes of the same sex. Regional differences in thyroid hormone levels suggested a latitudinal gradient, with higher values in southern than in central Ontario. Hormone of artificially fed deer were elevated when compared with animals that consumed only natural browse. Hormone levels were also higher in deer provided with food supplements of higher protein content. Extremely low winter T3 and T4 concentrations were found in malnourished deer. It is concluded that thyroid hormones in deer blood are influenced by current food intake and quality of nutrition. The potential for T3 and T4 as indicators of range quality is discussed.
Helminths from spring and fall migrant bufflehead ducks (Bucephala albeola) at Delta, Manitoba, Canada
Authors: Ewart Michael J. , McLaughlin J. D.
Published: February 2008

The digestive tracts of one local, eight spring migrant, and 16 fall migrant bufflehead ducks (Bucephala albeola L.) collected at Delta, Manitoba, were examined for helminths. Twenty-five species (5 nematode, 8 trematode, 11 cestode, and 1 acanthocephalan) were found. Thirteen species occurred in both spring and fall migrants, four occurred in spring migrants only, and six were found only in fall migrants. The species composition of the helminth fauna of buffleheads resembles that of lesser scaup more closely than that of any other anatid species studied to date.
Diving behaviour of lactating southern sea lions (Otaria flavescens) in Patagonia
Authors: Werner Rodolfo , Campagna Claudio
Published: February 2008

The diving behaviour of six lactating female southern sea lions (Otaria flavescens) was recorded during 52.4 animal-days at sea. Information was obtained from 18 057 dives. Females spent 52.7 ± 6.2% of the time at sea diving. Median and maximum dive depths ranged from 19 to 62 and from 97 to 175 m, respectively. Dives were short, with median and maximum durations ranging from 2.1 to 3.2 and from 4.4 to 7.7 min, respectively. Dives deeper than 10 m represented 56 – 89% of total dives and involved 93 – 97% of total diving time. Mean dive depth and duration of dives greater than 10 m were 61 m and 3 min, respectively. Most of these dives (69%) had a flat-bottomed U-shaped profile, bottom time constituting about half of the dive duration. Shallow dives, with a modal depth of 2 m, were short (median duration 0.1 –0.8 min), with virtually no time spent at the bottom of the dive. During trips to sea, which ranged from less than 1 day to more than 4 days, females dove continuously. Mean dive frequency was between 11 and 19 per hour. Surface intervals were short (median 0.9–1.2 min) and there was no apparent diel variation in dive depth or frequency. The estimated aerobic dive limit of the females was exceeded on only a few dives (0.7 – 6.2%). Transit to potential foraging areas took 0.2–8.3 h.
Fish age, nematode (Philonema oncorhynchi) infection, and development of sexual dimorphism by the adult male sockeye salmon, Oncorhynchus nerka, in western Alaska
Authors: Berg Ole Kristian , Foote Chris J. , Quinn Thomas P.
Published: February 2008

Of 255 mature male sockeye salmon (Oncorhynchus nerka) from two Alaskan lakes (Aleknagik and Iliamna), 254 (99.6%) were infected with the nematode Philonema oncorhynchi with a mean wet mass of 3.1 g (SD = 3.4 g) of nematodes. Fish that had spent 1 year in the lake prior to seaward migration had significantly lower parasite masses than those that had spent 2 years in the lake (2.7 vs. 4.1 g). However, there was no significant difference in parasite masses between lakes or among spawning populations within the lakes for fish of a given age or of all ages combined, even though the populations differed in age composition. The variation in relative parasite mass (mass of parasite (g)/mass of fish (kg)) was mainly explained by the significant variation in total mass of the parasites and the sea age of the fish. Thus, total parasite mass was correlated with the duration of residence in fresh water, while the relative parasite mass was correlated with fish size, and hence with the duration of residence in the sea. In spite of heavy infections (up to 28 g of nematodes) in many salmon, there were no corresponding reductions in mass/length or in the development of two sexually dimorphic features, body depth and snout length. Thus, parasite infection did not appear to affect traits under sexual selection, as hypothesized by Hamilton and Zuk.
Haematology and clinical chemistry values for harbour seals (Phoca vitulina) fed environmentally contaminated herring remain within normal ranges
Authors: Swart Rik L. de , Ross Peter S. , Vedder Lies J. , Boink Fons B. T. J. , Reijnders Peter J. H. , Mulder Paul G. H. , Osterhaus Albert D. M. E.
Published: February 2008

Twenty-two young harbour seals (Phoca vitulina) were fed herring from either the relatively unpolluted Atlantic Ocean or the heavily polluted Baltic Sea as part of a 2½-year immunotoxicological study. Blood samples taken at regular intervals were analyzed for routine haematology and clinical chemistry. Minimal differences between the two groups were observed in these parameters over the course of the experiment. Of the 20 clinical chemistry parameters analyzed, slight differences were found in serum levels of urea, creatinine, magnesium, and cholesterol. In haematology profiles, red blood cell counts and haematocrit values were higher in seals fed Baltic herring, but these differences diminished over time. Neutrophil counts were also higher in this group of seals, especially during the second half of the feeding study. Factors affecting haematological and clinical chemistry parameters within feeding groups included gender, age, and season. The data collected demonstrate a relative insensitivity of clinical chemistry parameters to the effects of chronic exposure to environmental contaminants accumulated through the food chain, but suggest the induction of clear alterations in differential white blood cell counts. In addition, a comprehensive set of normal ranges for healthy harbour seals is presented.
Effect of flower complexity on relearning flower-handling skills in bumble bees
Authors: Gegear Robert J. , Laverty Terence M.
Published: February 2008

Pollinators often forage sequentially among the flowers of the same plant species while bypassing flowers of other rewarding species. Darwin proposed that it is more efficient for pollinators to remain constant to one plant species because switching to a second species interferes with their ability to recall a previously learned flower-handling technique. This interference hypothesis was tested using Bombus impatiens workers. Bees that had learned to handle one type of flower (species A) were retested on species A after they had learned to handle a second type of flower (species B). Interference effects were detected by comparing flower access times (time to insert the tongue into the flower) during the retesting period with initial access times on species A. Bees retested on both simple (red clover, Trifolium pratense) and complex (toadflax, Linaria vulgaris) flowers showed no evidence of interference after learning simple-flowered plant species (blueweed, Echium vulgare; purple loosestrife, Lythrum salicaria). However, bees relearning the complex flowers of toadflax showed a 2.2-s (81%) increase over their initial access time after switching to a second complex-flowered species (orange touch-me-not, Impatiens capensis). These results suggest that the interference effects incurred by bees switching between toadflax and orange touch-me-not under biologically realistic conditions are relatively small, and are unlikely to account for flower constancy in bumble bees.
Artificial diets in sea urchin culture: effects of dietary protein level and other additives on egg quality, larval morphometries, and larval survival in the green sea urchin, Strongylocentrotus droebachiensis
Authors: Jong-Westman Marja de , Qian Pei-Yuan , March Beryl E. , Carefoot Thomas H.
Published: February 2008

The effect of artificial diets on the size and energy content of eggs and morphometry, survival, and metamorphic success of larvae was investigated in the green sea urchin, Strongylocentrotus droebachiensis, from the standpoint of developing a good broodstock diet for culturists. Groups of sea urchins were fed eight diets over a period of 9 months, then five of these dietary groups were selected for detailed larval-growth studies. The artificial diets differed in protein content and in various additives including mannitol, algin, cholesterol, and β-carotene; a diet of air-dried kelp was also included. Egg-energy content was highest on a high-protein diet with cholesterol and β-carotene additives, and the largest eggs so far recorded for the species (2.39 mm3 × 10−3) were produced on a high-protein diet with cholesterol additive. Larval survival to metamorphosis was >92% for all diets save for kelp (<5%). Kelp-fed adults also produced poorly metamorphosing larvae (<2%), suggesting that air-drying causes chemical changes in the kelp that are ultimately detrimental to larval health. Larval developmental rates were fastest on the high-protein β-carotene formulation. Larvae from this diet group also had the longest arms relative to body length, largest rudiment diameter, largest absolute and relative ciliated-band length (for efficient feeding), and had a high percentage of metamorphosis. These data suggest that a high-protein β-carotene diet will be useful for conditioning broodstock by prospective sea urchin culturists.
Spatial dynamics of fox squirrels (Sciurus niger) in fragmented landscapes
Authors: Sheperd B. Forrest , Swihart Robert K.
Published: February 2008

We examined the spatial dynamics of fox squirrels (Sciurus niger) occupying 12 woodland sites in a predominantly agricultural landscape of west-central Indiana. The 12 sites represented woodlands of varying degrees of isolation and size. Forty-nine adult fox squirrels were fitted with radio collars and monitored from May 1993 through September 1994. No movements of collared adults were observed between wooded sites during the study, although squirrels traveled 200–500 m from woodlots along hedgerows, and 2.6% of observations occurred in agricultural fields. Multiple regression revealed a positive linear relationship between home-range size and woodland size, with larger home ranges in the growing season. Home-range size was not related to woodland isolation, squirrel density, or sex. We found no evidence of spatial interactions between pairs of squirrels (i.e., male–male, male–female, female–female) at resolutions of 20, 40, or 100 m. Excursions beyond a core area were of relatively greater magnitude for squirrels occupying continuous forest. Agriculturally induced fragmentation of forests appears to restrict movements of adult fox squirrels, despite the well-documented ability of the species to persist in such a landscape.
Le vol en tandem chez le vautour fauve (Gyps fulvus)
Authors: Mouze Michel , Bagnolini Constant
Published: February 2008

Tandem flight is a formation that momentarily reunites two vultures flying one above the other at a very short distance. Our study adds the following points to our current knowledge of the subject: (i) the onset of tandem flight is always initiated by only one of the two birds (bird A) that positions itself above the other (tandem A/B), whereas its disruption can be initiated by either of the birds; (ii) the position of the wings in bird A makes its flight very unstable, which ensures maneuverability in dealing with the turbulence caused by bird B. The latter has a more peaceful flight, apparently independent of bird A; (iii) these tandem flights have a mean duration of about 10 s and always follow a straight course; (iv) most frequently, tandem flights reunite birds that are mating partners, and the female usually occupies the top position. We hypothesize that this type of flight may enhance the aerodynamic performance of the united birds, further tightening the bonds between pairs. This association seems to serve as a model to other vultures, which sometimes join the paired birds. The piling up that results often gives rise to aggressive behaviours that reflect the rivalry between all these birds.[Journal translation]
Anatomy and morphology of the cornea of bovine eyes from a slaughterhouse
Authors: Doughty Michael J. , Petrou Stavros , Macmillan Heather
Published: February 2008

Over a 1-year period, isolated bovine eyes were obtained from a slaughterhouse and assessed within 3 h post mortem. The gross disposition (including damage or disease) and corneal surface characteristics (overall appearance and wettability) were assessed by visual inspection and light and scanning electron microscopy. The results from 315 eyes (assessed to be free of gross abnormalities or damage) showed that the corneal thickness was 1015 ± 104 μm (mean ± SD; n = 315). Measures on 100 of these eyes revealed corneal dimensions averaging 29.8 ± 1.3 mm horizontally and 23.9 ± 1.5 mm vertically. The horizontal corneal diameter was greater in eyes with thicker corneas (r = 0.917). Regardless of thickness, corneas evaluated within 3 h post mortem had a uniform thickness within ± 3% from center to edge. Histology and scanning electron microscopy revealed that even corneas subjectively assessed to be in good condition had relatively large numbers of exfoliating cells at the epithelial surface, indicating that the corneal surface of bovine eyes from the slaughterhouse is likely to be slightly compromised. Scanning electron microscopy showed the endothelium to be a mosaic of uniformly sized polygons of which 67.1 ± 2.7% were six-sided cells (hexagons).
Influence of food availability on interactions between Larus cachinnans and L. audouinii
Authors: González-Solís Jacob , Ruiz Xavier , Jover Lluis
Published: February 2008

Predatory and (or) kleptoparasitic interactions are greatly facilitated in mixed-species gulleries, particularly when one of the species is larger than the others. Larus audouinii, the Audouin's gull, is a threatened species breeding in sympatry with the larger L. cachinnans, the yellow-legged gull, throughout the Mediterranean. The yellow-legged gull has often been cited as the main threat to the Audouin's gull. On the Chafarinas Islands, the second largest breeding place for Audouin's gulls in the world, both gull species depend largely on commercial fisheries for food. We analyze the influence of food availability, assessed through fishery activity, on the frequency and intensity of interaction pressure by yellow-legged gulls upon Audouin's gulls during the breeding season. We studied five different types of interaction: (1) flyovers of yellow-legged gulls; (2) ground intrusions; (3) egg predation; (4) chick predation, and (5) aerial kleptoparasitism. Moreover, intensity of interaction pressure was assessed using logistic regression analysis to build a model of the"relationship between Audouin's gulls' response to yellow-legged gull flyovers as a dependent variable and fishing fleet activity as an independent variable. All interactions except aerial kleptoparasitism were significantly more frequent during days without sardine fishery activity. However, chick predation is significantly higher only during the period when yellow-legged gull has fledglings. Overall, the results of the estimated logistic model indicate a positive association between depleted food and the response by Audouin's gulls to aerial intrusions.
Ontogenesis of the biliary tract in a teleost, the sea bass Dicentratchus labrax L.
Authors: Diaz Jean Pierre , Connes Robert
Published: February 2008

Ontogenesis of the biliary tract in the sea bass Dicentrarchus labrax was studied using transmission electron microscopy from hatching to 3 months of age. The biliary intrahepatic network and extrahepatic ducts develop during primordial liver differentiation. When hepatoblasts form groups and polarise, they create bile canaliculi at their apical pole. The main characteristic of these bile canaliculi is that they are roughly spherical. The biliary epithelial cells first appear just before mouth opening in prelarvae (day 5 after hatching). They constitute not only composite canaliculi with hepatocytes, but also cholangioles. Biliary ductules and ducts are visible from day 10 onward. During ontogenesis, the primordial liver separates from the wall of the gut but remains connected to it by a cell cord. This cell cord becomes tubular, with an axial cavity dilating at the other end and giving successively the choledoc duct, cystic duct, and gall bladder.
Digestive efficiency and gut morphology of omnivorous and herbivorous African tortoises
Authors: Hailey Adrian
Published: February 2008

Most of the 42 living species of tortoise (Testudinidae) are herbivorous, feeding largely on vascular plants, with the exception of the genus Kinixys, which is omnivorous. A comparison of Kinixys spekii and Geochelone pardalis showed the following significant differences. The large intestine was shorter in K. spekii (86% of plastron length and 1.8% of body mass) than in G. pardalis (246 and 2.5%) and held a smaller proportion of the total gut contents (44 and 62%, respectively). The apparent digestibility coefficient (ADC) of organic matter was lower in K. spekii (77%) than in G. pardalis (82%) fed kale; the ADC of holocellulose was higher and did not differ between the two species. Kinixys spekii did not readily consume grass, which is more difficult to digest than kale; the ADC of organic matter was 64% in G. pardalis. The time to first excretion (t0) was lower in K. spekii (2.2 days) than in G. pardalis (3.8 days). Other measures of retention time (t50, tmax, and [Formula: see text]) did not differ between the species, or between the two diets in G. pardalis. Analysis of published data on chelonians fed foliage shows that the ratio of large intestine to small intestine lengths is significantly related to gut retention time (r = 0.88) but not to the ADC (r = −0.28). Thus, although the short large intestine of K. spekii slightly reduces the gut retention time and digestibility of dicotyledonous leaves, the most important effect is a low ability to process grass and other coarse vegetation.
A simple and effective chemiluminescent DNA fingerprinting technique using digoxigenin-labelled minisatellite probes
Authors: Gissing Graeme J. , Crease Teresa J.
Published: February 2008

DNA fingerprinting has become a powerful tool in behaviourial and evolutionary ecology. However, investigators have been limited in their access to this technique because of the need for special radioisotope facilities. We present an alternative, non-isotopic DNA fingerprinting technique based on chemiluminescent detection of digoxigenin-labelled minisatellite probes. This methodology should provide a greater number of researchers with access to DNA fingerprinting without the need for special laboratory facilities.
INFORMATION-BASED ASSET PRICING
Authors: BRODY DORJE C. , HUGHSTON LANE P. , MACRINA ANDREA
Published: February 2008

A new framework for asset price dynamics is introduced in which the concept of noisy information about future cash flows is used to derive the corresponding price processes. In this framework an asset is defined by its cash-flow structure. Each cash flow is modelled by a random variable that can be expressed as a function of a collection of independent random variables called market factors. With each such "X-factor" we associate a market information process, the values of which we assume are accessible to market participants. Each information process consists of a sum of two terms; one contains true information about the value of the associated market factor, and the other represents "noise". The noise term is modelled by an independent Brownian bridge that spans the interval from the present to the time at which the value of the factor is revealed. The market filtration is assumed to be that generated by the aggregate of the independent information processes. The price of an asset is given by the expectation of the discounted cash flows in the risk-neutral measure, conditional on the information provided by the market filtration. In the case where the cash flows are the dividend payments associated with equities, an explicit model is obtained for the share-price process. Dividend growth is taken into account by introducing appropriate structure on the market factors. The prices of options on dividend-paying assets are derived. Remarkably, the resulting formula for the price of a European-style call option is of the Black–Scholes–Merton type. We consider the case where the rate at which information is revealed to the market is constant, and the case where the information rate varies in time. Option pricing formulae are obtained for both cases. The information-based framework generates a natural explanation for the origin of stochastic volatility in financial markets, without the need for specifying on an ad hoc basis the dynamics of the volatility.
In Human Leukemia Cells Ephrin-B–Induced Invasive Activity Is Supported by Lck and Is Associated with Reassembling of Lipid Raft Signaling Complexes
Authors: Jiang Guangping , Freywald Tanya , Webster Jarret , Kozan Daniel , Geyer Ron , DeCoteau John , Narendran Aru , Freywald Andrew
Published: February 2008

Proteins of the ephrin-B group operate in nonlymphoid cells through the control of their migration and attachment, and are crucial for the development of the vascular, lymphatic, and nervous systems. Ephrin-B activity is deregulated in various nonlymphoid malignancies; however, their precise role in cancer has only started to be addressed. We show here that ephrin-B1, a member of the ephrin-B group, is expressed in pediatric T-cell leukemias, including leukemia cell line Jurkat. Treatment of Jurkat cells with ephrin-B–stimulating EphB3 enhances ephrin-B1 phosphorylation and induces its relocalization into lipid rafts. These events are mediated by the T lineage–specific kinase, Lck, as ephrin-B1 phosphorylation and lipid raft association are blocked in the Lck-deficient clone of Jurkat, JCAM1.6. Ephrin-B1 also induces colocalization of the CrkL and Rac1 cytoskeleton regulators and initiates in leukemic cells a strong repulsive response. The absence of Lck blocks ephrin-B1–induced signaling and repulsion, confirming the essential role for Lck in ephrin-B1–mediated responses. This shows a new role for ephrin-B1 in the regulation of leukemic cells through the Lck-dependent Rac1 colocalization with its signaling partner, CrkL, in lipid rafts. In agreement with its repulsive action, ephrin-B1 seems to support metastatic properties of leukemic cells, as suppression of ephrin-B1 signaling inhibits their invasiveness. Because ephrin-B1–activating EphB proteins are ubiquitously expressed, our findings suggest that ephrin-B1 is likely to play an important role in the regulation of malignant T lymphocytes through the control of lipid-raft–associated signaling, adhesion, and invasive activity, and therefore may represent a novel target for cancer treatment. (Mol Cancer Res 2008;6(2):291–305)
Oncogenic Activation of the Human Pygopus2 Promoter by E74-Like Factor-1
Authors: Andrews Phillip G.P. , Kennedy Mark W. , Popadiuk Cathy M. , Kao Kenneth R.
Published: February 2008

Pygopus is a component of the T-cell factor/β-catenin transcriptional complex essential for activation of Wnt target genes and is also required for cell regulation in the absence of Wnt signaling. Human Pygopus2 (hPygo2) is overexpressed in a high proportion of breast and epithelial ovarian malignant tumors and is required for the growth of several cell lines derived from these carcinomas. The mechanisms regulating hPygo2 gene activation, however, are unknown. Here, we have determined cis- and trans-interacting factors responsible for hPygo2 expression in cancer. The minimal region required for a maximal 109-fold activation of the hPygo2 promoter in MCF-7 breast cancer cells is 48 bp upstream of the start of transcription. Within 25 bp of the transcriptional start, there are two overlapping tandem Ets transcription factor–binding sites, which are critical for hPygo2 promoter activity. In vitro DNA pull-down assays and proteomic analyses identified the Ets family members Elk-1 and E74-like factor-1 (Elf-1) as potential hPygo2 promoter binding factors, whereas in vivo chromatin immunoprecipitation assays verified that only Elf-1 specifically bound to the hPygo2 promoter in MCF-7 cells. Modulation of elf-1 in MCF-7 cells by silencing via RNA interference or overexpression caused a corresponding decrease or increase, respectively, in hPygo2 promoter activity. Overexpression of Elf-1 in HeLa cells, in which Elf-1 is expressed at a lower level than in MCF-7 cells, caused a 4-fold increase in endogenous hPygo2 mRNA levels. These results provide new evidence that Elf-1 is involved in transcriptional activation of hPygo2. Like hPygo2, previous studies implicated Elf-1 in breast and ovarian cancer and our present findings suggest that the oncogenic requirement of hPygo2 is fulfilled, in part, by Elf-1. (Mol Cancer Res 2008;6(2):259–66)
c-Myc Inhibits Ras-Mediated Differentiation of Pheochromocytoma Cells by Blocking c-Jun Up-Regulation
Authors: Vaqué José P. , Fernández-García Belén , García-Sanz Pablo , Ferrandiz Nuria , Bretones Gabriel , Calvo Fernando , Crespo Piero , Marín María C. , León Javier
Published: February 2008

Although mutant Ras proteins were originally described as transforming oncoproteins, they induce growth arrest, senescence, and/or differentiation in many cell types. c-Myc is an oncogenic transcription factor that cooperates with Ras in cellular transformation and oncogenesis. However, the Myc-Ras relationship in cellular differentiation is largely unknown. Here, we have analyzed the effects of c-Myc on PC12-derived cells (UR61 cell line), harboring an inducible N-Ras oncogene. In these cells, Ras activation induces neuronal-like differentiation by a process involving c-Jun activation. We found that c-Myc inhibited Ras-mediated differentiation by a mechanism that involves the blockade of c-Jun induction in response to Ras signal. Accordingly, ectopically expressed c-Jun could bypass c-Myc impediment of Ras-induced differentiation and activator protein 1 activation. Interestingly, it did not rescue the proliferative arrest elicited by Ras and did not enhance the differentiation-associated apoptosis. The blockade of Ras-mediated induction of c-Jun takes place at the level of c-Jun proximal promoter. Mutational analysis revealed that c-Myc regions involved in DNA binding and transactivation are required to block differentiation and c-Jun induction. c-Myc does not seem to require Miz-1 to inhibit differentiation and block c-Jun induction. Furthermore, Max is not required for c-Myc activity, as UR61 cells lack a functional Max gene. c-Myc–inhibitory effect on the Ras/c-Jun connection is not restricted to UR61 cells as it can occur in other cell types as K562 or HEK293. In conclusion, we describe a novel interplay between c-Myc and c-Jun that controls the ability of Ras to trigger the differentiation program of pheochromocytoma cells. (Mol Cancer Res 2008;6(2):325–39)