bluuebunny/crossref_metadata_2025 huggingface dataset:
A quantum mechanical discussion of Rabi oscillations
Authors: Hoy G R , Odeurs J
Published: August 2008

In 1937, Rabi treated the problem of a magnetic moment in an applied time-dependent magnetic field. This became the well-known magnetic resonance situation. The Hamiltonian is often taken to be [Formula: see text] = – µ · [[Formula: see text]]. In this paper, the Rabi oscillations formula, describing the spin flipping, is derived in an unusual way. The method uses a modification of a method due to Heitler. In the Heitler method, one uses the Interaction Picture of quantum mechanics. Due to the time-dependence in the problem, the usual Heitler method fails. However, the solution is found after quantizing the electromagnetic field. To better understand the origin of the spin flipping, the analogous time-independent problem is also solved. It is made clear that the origin of the Rabi oscillations is not due to the time-dependent magnetic field. The spin flipping is essentially due to the fact that the spin system, when initially prepared, is not in an eigenstate of the Hamiltonian. Thus, as times progresses, the system naturally evolves through the noneigenstate basis states.PACS Nos.: 03.65.–w, 76.20.+q
Multiple effects of acid and aluminum on brood stock and progeny of fathead minnows, with emphasis on histopathology
Authors: Leino R. L. , McCormick J. H. , Jensen K. M.
Published: August 2008

Thirty-day-old fathead minnows, Pimephales promelas, were reared at different pH values in softened Lake Superior water enriched with aluminum: pH 7.5–35 μg Al/L, pH 5.5–30 μg Al/L, pH 5.2–35 and 60 μg Al/L, including a background level of 15 μg Al/L, and at pH 7.5, 6.0, 5.5, and 5.2 at background Al levels. Spawning was greatly reduced at pH 6.0, pH 5.5–30 μg Al/L, and pH 5.5 and failed at pH 5.2 with or without added Al. The adult brood stock exhibited abnormalities at low pH, which could have contributed to poor spawning success or energy utilization: (i) thickened respiratory epithelium in the gills, (ii) hyperplasia of primary lamellar epithelium in the gills, (iii) increased number of gill chloride cells, (iv) reduced gill perfusion, (v) immature ovaries and oocyte atresia, (vi) immature and pathologic testes, (vii) abnormal distal tubules and collecting ducts in the kidneys, and (viii) reduced blood osmolality at pH 5.5 and 5.2 when no Al was added. Hatching success and larval survival were reduced when spawning occurred at or below pH 6.0; these larvae often had retarded swim bladder development and yolk absorption and some stages had abnormal gills, kidneys, and liver glycogen reserves. This study further supports the relationship between acidification, histological changes, ionoregulatory disturbances, altered energy metabolism, and recruitment failure.
On the morphology, morphogenesis, and argyrome of Disematostoma buetschlii (Ciliophora, Frontoniidae)
Authors: Martin-Gonzalez Ana , Serrano Susana , Fernández-Galiano Dimas
Published: August 2008

Disematostoma buetschlii is a lanceolate ciliate about 198–106 × 164–90 μm in size. The nuclear apparatus consists of an elongate macronucleus and three or four spherical micronuclei. The somatic infraciliature is made up of 64–75 kineties arranged asymmetrically, of which five or six rows are postoral. The dorsal polar band is the result of the convergence of the posterior ends of all the dorsal somatic kineties. There is a row of 15–18 pairs of kinetosomes in the middle of this band. The argyrome is a network of small rectangular polygons. The oral infraciliature comprises three peniculi with three, four, and four rows of kinetosomes, respectively, and a paroral membrane that is a stichodyad. This species has four or five vestibular kineties and one contractile vacuole pore. Stomatogenesis is buccokinetal; the oral infraciliature of the opisthe comes from the proliferation of the parental paroral membrane.
Plasma levels of five androgens and 17α-hydroxy-20β-dihydroprogesterone in immature and mature male Baltic salmon (Salmo salar) parr, and the effects of castration and androgen replacement in mature parr
Authors: Mayer Ian , Berglund Ingemar , Rydevik Magnus , Borg Bertil , Schulz Rüdiger
Published: August 2008

During the spawning period, the plasma levels of the androgens 11-ketotestosterone, testosterone, 11β-hydroxytestosterone, 11β-hydroxyandrostenedione, 11-ketoandrostenedione, and of the progestin 17α-hydroxy-20β-dihydroprogesterone were higher in mature compared with immature male Baltic salmon parr. 11-Ketotestosterone was always found to be the predominant androgen in the plasma of mature male parr and mature anadromous males. Mature male parr and large mature anadromous males had similar androgen profiles during the main spawning period, although 11-ketotestosterone tended to be higher in the mature anadromous males and testosterone was always higher in the mature male parr. At the time of the main spawning period, plasma levels of 17α-hydroxy-20β-dihydroprogesterone rose sharply in mature male parr, these levels being similar to those found in the plasma of large mature anadromous males. All measured androgens were low or nondetectable in castrated parr. Treatment of castrated parr with Silastic capsules containing 11-ketoandrostenedione resulted in high plasma 11-ketoandrostenedione levels and even higher levels of 11-ketotestosterone, indicating an extratesticular site of androgen conversion.
Nest-site characteristics of prairie shorebirds
Authors: Colwell Mark A. , Oring Lewis W.
Published: August 2008

Nest-site characteristics of eight shorebird species were studied during the period 1982–1984 at Last Mountain Lake National Wildlife Area in south central Saskatchewan. Plant species composition at nests varied significantly among species and was correlated with distance to bare ground and aquatic habitat. Flora at Wilson's phalarope (Phalaropus tricolor) nests was correlated with clutch initiation date, reflecting a seasonal shift in nesting habitat. Species differed significantly in cover types at nests. For American avocet (Recurvirostra americana), killdeer (Charadrius vociferus), and Wilson's phalarope, cover types differed between nests and random sites; cover types also differed between nest cups and the immediate surrounding habitat for killdeer and Wilson's phalarope. Interspecific differences in nest-site vegetation physiognomy were portrayed by the first two factors of a principal components analysis, which accounted for 73 and 22% of variance in the data, respectively. Principal components analysis assembled species on a habitat gradient that varied according to cover type, and vegetation density and heterogeneity.
Ingestion rate and body size in phagotrophic organisms
Authors: Capriulo Gerard M. , Lints David , Lewinter Martin
Published: August 2008

A general functional relationship between body weight (10−11 to 108 g) and ingestion rate has been found to exist throughout the protistan and metazoan kingdoms. Results, based on a mathematical interpretation of standardized, quantitative data, indicate that ingestion rate is a log–log linear function (i.e., power function) of body weight (I = a W0.829 for cold-blooded forms and I = a W0.778 for warm-blooded forms, where I = ingestion rate and W = body weight). The slopes of the cold-blooded and warm-blooded regression lines are not significantly different from each other (i.e., they are parallel). This allows one to use the difference between the respective curves to estimate the weight-specific cost of warm-bloodedness. Such an analysis of the data indicates that a warm-blooded organism must ingest about ten times more food per unit body weight than cold-blooded forms. This functional relationship may be a manifestation of the physiological constraints placed on organisms by surface area to volume ratio phenomena, related to absorptive surfaces, mouth areas, and body volumes. The present analysis suggests that flexibility in functional design is limited by physical phenomena which affect phenotypic plasticity.
Influence of parental stock and incubation temperature on the early development of coho salmon (Oncorhynchus kisutch) in British Columbia
Authors: Murray C. B. , Beacham T. D. , McPhail J. D.
Published: August 2008

Coho salmon (Oncorhynchus kisutch) stocks in British Columbia spawning from October to April were surveyed for variation in developmental characteristics at incubation temperatures from 1.5 to 15 °C. There were no trends in embryo or alevin survival rates associated with spawning time or spawning temperature. The highest embryo and alevin survival rates occurred at 4 or 5 °C and complete mortality generally occurred at 14 or 15 °C. Vancouver and Queen Charlotte Island stocks had lower survival rates at 1.5 and 2 °C than did mainland stocks. Time to 50% hatching and 50% emergence varied inversely with incubation temperature. Alevin hatching time for the Pallant Creek stock on the Queen Charlotte Islands was later than for all other stocks. Stocks had different trends in alevin and fry length and weight with respect to incubation temperature. Northern stocks tended to be more efficient than southern stocks at converting yolk to body tissue at 1.5 and 2 °C, as were mainland stocks compared with island stocks.
Primary setae and pores on the last abdominal segment and the urogomphi of larval Hydroporinae (Coleoptera: Adephaga: Dytiscidae), with notes on other dytiscid larvae
Authors: Alarie Y. , Harper P. P.
Published: August 2008

The first instar larvae of 24 North American species of Hydroporinae (Coleoptera: Dytiscidae), 6 species belonging to the three other dytiscid subfamilies, and 2 species each of Amphizoidae and Hygrobiidae are analyzed. The ancestral system of primary setae and pores on the last abdominal segment and the urogomphi of Hydroporinae larvae is deduced. Generic differences are discussed in a phylogenetic perspective. Laccornis Des Gozis is confirmed as one of the most primitive lineages in the Hydroporinae and we suggest that Hygrotus Stephens could be more evolved than the closely related genus Hydroporus Clairville. Informations on the primary chaetotaxy of other dytiscid larvae are also mentioned.
A pseudoscorpion from arctic Canada (Pseudoscorpionida, Chernetidae)
Authors: Muchmore William B.
Published: August 2008

Many terrestrial arthropods have been reported from arctic regions of North America, but until now, no named pseudoscorpion has been recorded north of latitude 62°. A new species, Wyochernes arcticus, is described from the Yukon Territory at 69°10′N.
Reproductive rate and longevity in the waterstrider, Gerris buenoi
Authors: Rowe Locke , Scudder G. G. E.
Published: August 2008

In this laboratory study, the relationship between egg output and longevity at three food levels is examined in adults of the waterstrider, Gerris buenoi. There was no effect of food level on estimated lifetime fecundity. However, egg production rate was halved under low food conditions. This reduction in reproductive rate was balanced by a near doubling of female longevity under food scarcity. Males lived longer than females, but longevity was not significantly related to food level. Egg fertility was not significantly different across treatments. Body size accounted for less than 5% of the variation in all these variables. These data support a central component of life history theory: the assumption that there is a trade off between reproductive rate and longevity.
Infanticide by female wolves
Authors: McLeod Peter J.
Published: August 2008

Video recordings made inside wolf dens chronicle two episodes of infanticide by different α females within a captive pack of timber wolves (Canis lupus). In one instance, infanticidal behaviour was interspersed with maternal behaviour. These cases are discussed in terms of the proximate causes of infanticide. It is also suggested that the killing of pups born to subordinate females by α females may be a common occurrence in both captive and free-ranging wolf packs.
Facilitation sociale sous un cycle de lumière–obscurité et sous des conditions constantes de luminosité chez le Carouge à épaulettes (Agelaius phoeniceus)
Authors: Gauthier Serge , Cyr André
Published: August 2008

Social facilitation is an important factor of behaviour synchronization in gregarious birds. Social facilitation was measured and compared in conditions of constant light or during a light–darkness (LD) cycle, using ten Redwing Blackbirds (Agelaius phoeniceus), to determine the effects of social contacts between individuals in the absence of an LD cycle. Results showed that the LD cycle and social contacts had different effects depending on the type of behaviour involved. The LD cycle is more efficient than social stimulation in synchronizing activities, and social stimulation alone cannot synchronize feeding behaviour in individuals, although it can reduce the frequency of locomotory behaviours under conditions of alternating light and darkness. Each factor, LD cycle or social stimulation, can by itself have an important effect on the synchronization of grooming behaviours and the combination of the two factors further enhances synchrony. The role of social stimulation as a supplementary and complementary agent in synchronizing the activities in Redwing Blackbirds is discussed.
Experimental investigations of the evolutionary significance of sexually dimorphic nuptial colouration in Gasterosteus aculeatus (L.): the relationship between male colour and female behaviour
Authors: McLennan D. A. , McPhail J. D.
Published: August 2008

Cladistic analysis of behavioural interactions during a series of female choice trials revealed three groups of reproductively unsuccessful males in a population of anadromous Gasterosteus aculeatus: inactive losers (losing male did not participate in choice test), active losers (losing male active during choice test), and fighting losers (subgroup of active losers defined by the observation that the female did not immediately follow the first male to approach her). The inactive losers group represents a "no choice" situation. In the remaining two groups, females responded preferentially to the most intensely coloured member of the competing male pair. This preferential response was strongest during the prechoice, captive presentation where the majority of females oriented head-up to, and tracked, the brighter red male. Once released, the female's initial response to the brighter courtship signal was overridden by the behavioural actions of the duller intensity male in 4 out of 12 trials. Although two of these males eventually lost the female to their rival, the remaining two individuals succeeded in spawning. Overall, 10 of 12 females spawned with the brighter red male. Given the brief breeding season and the advantage enjoyed by the most brightly coloured males in mate attraction, a high level of territorial intrusion is one way for an individual to attract a mate if he is surrounded by more intensely coloured neighbours.
Redescriptions of Aspidodrilus and Pelmatodrilus, enchytraeids (Annelida, Oligochaeta) ectocommensal on earthworms
Authors: Coates Kathryn A.
Published: August 2008

Two ectocommensal enchytraeids living on earthworms, Aspidodrilus kelsalli Baylis, 1914 and Pelmatodrilus planariformis Moore, 1943, are both redescribed and confirmed to be valid enchytraeid taxa. Aspidodrilus eburneensis Baer, 1952 is a junior synonym of Aspidodrilus kelsalli. It is proposed that Aspidodrilus is phylogenetically near Henlea, whereas Pelmatodrilus is near the Enchytraeinae (Enchytraeus, Lumbricillus, and related genera). Thus, the two genera have evolved similar body forms and ectocommensal habits convergently.
Inoculation triggers freezing at high subzero temperatures in a freeze-tolerant frog (Rana sylvatica) and insect (Eurosta solidaginis)
Authors: Layne Jr. Jack R. , Lee Jr. Richard E. , Huang Janet L.
Published: August 2008

Freezing of animals is often portrayed to begin after they supercool several degrees Celsius below the melting point of body fluids. This supposition is based on laboratory protocol that usually exposes animals only to dry air during freezing episodes, whereas, in nature, animals may be in direct contact with external ice or snow at temperatures above the supercooling point of their body fluids. This raises the possibility that ice nucleation may occur across the epithelium or cuticle, causing the freezing of body fluids. We tested this possibility in two freeze-tolerant animals, the wood frog, Rana sylvatica, and the goldenrod gall fly, Eurosta solidaginis. Frogs remained supercooled for 3 h at −1.5 to −2.0 °C when kept on an unfrozen surface; however, they began to freeze in less than 30 s after coming in direct contact with ice crystals. Seeding occurred in less than 1 min across isolated patches of frog skin held in a modified Ussing chamber. Similarly, externally moistened larvae of E. solidaginis froze at higher temperatures than dry larvae. Likewise, within galls containing a relatively high water content (65.8%), larvae froze at higher temperatures than ones found in drier galls (19.6%). Therefore, animals may freeze at high subzero temperatures, at or near the melting point of their body fluids, owing to transepithelial ice inoculation. In E. solidaginis, exposure to sufficient moisture to trigger inoculation declines as winter approaches; thus, this avenue for freezing seems limited to autumn, when plant galls have a high water content. This study further emphasizes the need to use care in extrapolating laboratory-determined supercooling points as an approximation of the response of animals in the field.
Ecological adaptations and morphological variation in the posterior disc of larvae of Sciomyzidae (Diptera)
Authors: Vala Jean-Claude , Gasc Charles
Published: August 2008

The posterior part of segment 12 in the larvae of Sciomyzidae, commonly called the posterior disc, has four morphological aspects related to habitat and feeding behaviour. According to the variations observed, the following ecological categories can be used: (i) supra-aquatic species have well-developed float hairs (hydrofuge interspiracular processes) and long triangular peripheral lobes of the disc; (ii) semi-aquatic species have moderately developed float hairs and short triangular lobes; (iii) intermediate terrestrial species have very short float hairs and circular lobes; (iv) true terrestrial species have vestigial, scalelike float hairs and hemispherical lobes.
Virus-like particles from the poison glands of the parasitic wasp Biosteres longicaudatus (Hymenoptera: Braconidae)
Authors: Lawrence Pauline O. , Akin Debra
Published: August 2008

Two virus-like particles occur in the venom apparatus (poison glands) associated with the ovaries of the parasitic wasp Biosteres longicaudatus (Hymenoptera: Braconidae). The venom apparatus consists of accessory gland filaments (tubules) (AGFs) and a short, carrot-shaped, muscular sac, Dufour's gland. Rod-shaped particles measuring 250–300 nm long and 60–70 nm wide with convex ends occur in 100% of the cells examined along the middle third of the AGFs. These particles are associated with an electron-dense crystalline matrix within a stroma surrounded by vesicles. Similar particles are present in vacuoles in 76–90% of the epidermal cells in the pharate pupal host, Anastrepha suspensa (Diptera: Tephritidae), after parasitization by B. longicaudatus. The second type of particle is spherical and has an outer membrane with a beaded surface. It is about 250 nm in diameter and has an electron-dense biconcave central core with two lateral bodies, and resembles entomopoxviruses. Such particles occur within a stroma in 80–90% of the cells along the proximal third of the AGF, and within its lumen, to which the cells are connected by a short, cuticle-lined duct. These AGF cells are morphologically distinct from those containing the rod-shaped particles. The "mature" spherical particles accumulate in the Dufour's gland, which empties into the median oviduct, and are injected into the host by the wasp during oviposition. Similar particles are present in 63–80% of the hemocytes of parasitized hosts.
Differences in trap-finding behaviour of two populations of Austrosimulium bancrofti (Taylor) (Diptera: Simuliidae) in eastern Australia
Authors: Ballard J. W. O. , Morton K. J.
Published: August 2008

Three carbon dioxide baited silhouette traps of different shape and an animal-baited trap were used to evaluate trap- and host-finding behaviour of Austrosimulium bancrofti (Taylor) at two locations in eastern Australia. Highly significant effects influencing silhouette-trap-finding were incorporated into models that generated estimates of the numbers of flies captured under defined conditions. Estimates indicated that the effects of trap shape, hour after sunrise, experimental day, temperature, and wind speed differed at each location. Acclimation to local environmental conditions may explain differences in the silhouette trapping data, but the effects of trap shape and perhaps time of day were more difficult to explain. Austrosimulium bancrofti were attracted to bovines at both locations, whereas humans, bandicoots, and chickens were not attractive. It will be necessary to test a wider range of bait species before the host preferences of A. bancrofti at these locations can be determined.
Effect of water temperature on stomach evacuation rates, and estimation of daily food intake of bluegill sunfish (Lepomis macrochirus Rafinesque)
Authors: Booth D. J.
Published: August 2008

Field experiments were conducted over the summer of 1983 to determine food-evacuation rate and measure stomach fullness of bluegill sunfish (Lepomis macrochirus). A combination of these data gave estimates of daily food intake of fish. Fish were captured and held in large holding pens in Lake Opinicon, Ontario, Canada, and periodically subsampled over 24 h to monitor changes in mean weight of stomach contents. Stomach-evacuation rates obtained in this way increased significantly with water temperature over the range 10–25 °C. However, variation in stomach-evacuation rate was considerable, reducing the utility of water temperature as a predictor of stomach-evacuation rate. It is suggested that the simple field methods employed here to estimate stomach evacuation and food intake are more useful in the estimation of daily ration than the more commonly employed laboratory-based methods.
A comparison of the cold hardiness of populations of Delia radicum (L.) (Diptera: Anthomyiidae) from southern England and the Canadian Prairies
Authors: Turnock W. J. , Reader P. M. , Bracken G. K.
Published: August 2008

The Canadian population of Delia radicum is more cold hardy than the English population in that the supercooling point is slightly lower and overwintering pupae are less sensitive to lower temperatures and longer exposure times. However, the Canadian population is slightly less cold hardy at higher temperatures within the cold injury zone. Female D. radicum were more susceptible to cold-induced mortality than males among the Canadian population, but this sex difference was not significant in the English population. The proportion of malformed adults and the rate of postdiapause development were not related to cold injury in either population. The bounds of the cold injury zone for species or populations of freezing susceptible, diapausing insects plus the sensitivity of the species to cold injury within this zone can provide an ecologically sound method of describing cold hardiness. Sensitivity, measured by the slope of a regression describing the relationship between survival and the duration of exposure at a low temperature, can also be used to calculate the rate at which cold injury occurs at any temperature within the cold injury zone. This slope may reflect the overwintering conditions of a species or population because Canadian populations of both D. radicum and Mamestra configurata (Noctuidae) have similar coefficients, but these are very different from the coefficient of the English population of D. radicum. The supercooling point did not provide a useful indication of the susceptibility of these cold-hardy diapausing insects to cold injury.
Effects of low incubation temperatures during the pipped egg stage on hatchability and hatching times in domestic chickens and ring-billed gulls
Authors: Evans Roger M.
Published: August 2008

Gulls and some other species of birds are known to neglect pipped eggs that remain within the clutch after the first egg(s) hatch. I examined the effects of incubation neglect at this stage of development by cooling eggs in the laboratory. Domestic white leghorn chicken (Gallus gallus) eggs had significantly reduced hatchability and delayed hatch times when incubated at 30 or 27 °C from pipping until hatching. Cyclic cooling for 4 or 7 h out of every 8-h period produced intermediate effects. Pip-to-hatch interval was delayed by as much as 60% in ring-billed gull (Larus delawarensis) eggs incubated from pipping onwards at 33 °C. To the extent that the laboratory results can be extrapolated to natural incubation, results suggest that egg neglect and low incubation temperatures during the critical final stages of hatching could have adverse effects upon the last egg(s) to hatch within a clutch. Depending on the species, low temperature and retardation could increase chances that a late-hatched young will be left behind when the rest of the brood leaves the nest. Where the hatch is typically asychronous, low incubation temperatures after the first eggs begin to hatch could increase the degree of asynchrony and hence the competitive disadvantage of the last-hatched young.
Population and habitat characteristics of lynx and snowshoe hares in north central Washington
Authors: Koehler Gary M.
Published: August 2008

Lynx (Lynx canadensis) and snowshoe hare (Lepus americanus) population characteristics and use of habitats were studied during 1985–1987 in north central Washington. Lynx used areas above 1463 m elevation that were dominated by lodgepole pine (Pinus contorta) and Engelmann spruce – subalpine fir (Picea engelmannii – Abies lasiocarpa) cover types. Snowshoe hares were the most common prey of lynx, with remains of snowshoe hare occurring in 23 of 29 scats. Counts of tracks and pellets showed snowshoe hares to be most abundant in 20-year-old lodgepole pine stands. Fire suppression and natural fire frequencies in the past 5 decades has limited the amount of these early successional forests, which are important as habitat for snowshoe hares. Marginal habitat conditions for snowshoe hares probably resulted in a scarcity of prey in the study area and may explain the relatively large home ranges of lynx (69 ± 28 km2 for five males and 39 ± 2 km2 for two females), low density of adults (2.3 lynx/100 km2), and high kitten mortality rates (88% for eight kittens in three litters). Demographic characteristics of lynx in the study area may be representative of lynx populations along the southern periphery of their range where habitat conditions are marginal for lynx and snowshoe hares.
Coccidian parasites (Apicomplexa: Eimeriidae) of Chelydra serpentina (Testudines: Chelydridae) from Arkansas and Texas, U.S.A., with descriptions of Isospora chelydrae sp. nov. and Eimeria serpentina sp. nov.
Authors: McAllister Chris T. , Upton Steve J. , Trauth Stanley E.
Published: August 2008

Two new species of Coccidia (Apicocomplexa: Eimeriidae) are described from the feces of common snapping turtles, Chelydra serpentina serpentina, from Arkansas and Texas, U.S.A. Oocysts of Isospora chelydrae sp.nov. were found in 3/9 (33%) turtles and are symmetrical, 9.6 × 6.8 (9–11 × 6–8) μm, and bear one conical projection on one side of the oocyst and two conical projections on the opposite side of the oocyst, 1.5 – 1.6 μm long; shape index 1.4 (1.2 – 1.6). A micropyle, oocyst residuum, and polar granule are absent. Sporocysts are ellipsoid, 5.8 × 4.0 (5 – 7 × 3.8 – 4.2) μm, with a small Stieda body but no substieda body; shape index 1.5 (1.3 – 1.7). Oocysts of Eimeria serpentina sp.nov. were found in 4/9 (44%) of the turtles and are ellipsoid, 12.8 × 8.1 (11 – 15 × 7 – 10) μm; shape index 1.6 (1.4 – 1.9). A micropyle, oocyst residuum, and polar granule are absent. Sporocysts are ellipsoid, 7.6 × 4.1 (6 – 9 × 4 – 5) μm, each with a Stieda body but a substieda body is absent; shape index 1.8 (1.5 – 2.1). In addition, E. chelydrae Ernst, Stewart, Sampson, and Fincher, 1969 and E. filamentifera Wacha and Christiansen, 1979 were found in 4/9 (44%) and 1/9(11%) hosts, respectively.
Yolk proteins in salmon (Salmo salar) oocytes, eyed eggs, and alevins differing in viability
Authors: Olin Thomas , Decken Alexandra von der
Published: August 2008

The developmental stages of oocytes, eyed eggs, and alevins from salmon (Salmo salar) were compared for their yolk protein composition. In oocytes, SDS–polyacrylamide gel electrophoresis showed high amounts of a protein with the molecular weight (Mr) of 94 000. In eyed eggs, the 94 000 protein decreased and was undetectable in the alevins. Furthermore, in eyed eggs the proteins of 67 000, 30 000, and 27 000 increased, while in the alevins the concentration of the 67 000 protein decreased and that of the 39 000 increased. Vitellogenin-specific antigen sites analyzed by immunoblotting were most pronounced with the proteins of 94 000, 67 000, 39 000, 30 000, 23 000, and 19 000. Separation of the yolk proteins by HPLC gave four peaks at 280 nm for all three developmental stages. Each peak consisted of several proteins as analyzed by SDS–polyacrylamide gel electrophoresis. The 7-day-old alevins sampled from groups of different parental origin showed differences in the amount of the 67 000 and 23 000 proteins. Expectancy of survival within the group in connection with a slow disappearance of the 67 000 and 23 000 proteins was statistically significant. A fast disappearance may be used as an indication of, but not as the reason for, a high mortality within one group of alevins.
Sinking depths of black-tailed deer in snow, and their indices
Authors: Bunnell F. L. , Parker K. L. , McNay R. S. , Hovey F. W.
Published: August 2008

Sinking depths in snow of a captive black-tailed deer (Odocoileus hemionus columbianus) were recorded in old-growth, second-growth, and recently clear-cut forests. Data were collected over a wide range of snow conditions. Snow hardness was extremely variable, even within 30 cm, and only weakly correlated with deer sinking depths (r = 0.52 for upper crust hardness). Snow density in the upper 48 cm of the snowpack was a better predictor of deer sinking depths (r2 = 0.65), but the best prediction was from density and hardness combined (r2 = 0.86). Snow depth alone was a poor predictor, because the deer rarely sank to the bottom of the snowpack (9 of 630 cases). Two indices of sinking depth were evaluated: human sinking depth and Hepburn's index. Human sinking depth was both a simpler and better predictor, especially when snow hardness values >256 g cm−2 (deer static foot loading) were eliminated (r2 = 0.65).
Studies on the scutal patterns of three South American Simulium species (Diptera: Simuliidae)
Authors: Lowry C. A. , Shelley A. J.
Published: August 2008

Scutal patterns of female Simulium quadrifidum, S. oyapockense s.I., and S. bipunctatum were studied with a light microscope, and these observations were compared with scutal morphology as seen with the scanning electron microscope (SEM). This study has shown that the pruinose scutal patterns seen in these species are due to the distribution of two distinct forms of microtrichia visible only with the SEM, with underlying pigmentation determining the background colouration. The importance of using a standardised lighting method on well-preserved specimens is emphasised.
Factors affecting swim bladder volume in rainbow trout (Oncorhynchus mykiss) held in gas supersaturated water
Authors: Shrimpton J. M. , Randall D. J. , Fidler L. E.
Published: August 2008

We examined the response of the rainbow trout (Oncorhynchus mykiss) swim bladder to gas supersaturated water. Cannulas positioned in the swim bladder of fish were connected to a pressure transducer, allowing direct measurement of swim bladder pressure. When denied access to the surface, fish held in supersaurated water showed an increase in swim bladder pressure. This response showed a strong dependence on the total gas pressure and the oxygen partial pressure of the water. The minimum level of gas supersaturation observed to cause this response corresponds to a ΔP of 27 mmHg [Formula: see text]; 1 mmHg = 133.3 Pa). The threshold ΔP for swim bladder inflation increased as the partial pressure of dissolved oxygen increased. Movement of supersaturated gases from the arterial system into the swim bladder is passive and causes a rise in swim bladder pressure until the diffusion gradient is nil or the gas is expelled through the pneumatic duct. The threshold for release of gas out the pneumatic duct is dependent on the size of the fish. Small fish have higher duct release pressures and are subject to a higher degree of pressure buildup within the swim bladder than larger fish.
The impact of two Chaoborus species on a zooplankton community
Authors: MacKay Neil A. , Carpenter Stephen R. , Soranno Patricia A. , Vanni Michael J.
Published: August 2008

The responses of a zooplankton community to Chaoborus predation were studied in large in situ mesocosms in Peter Lake. Chaoborus flavicans, the native chaoborid, significantly reduced the density of the dominant grazer, Daphnia pulex, in relation to controls that lacked Chaoborus. Chaoborus americanus, a species found only in fishless bogs, reduced Da. pulex densities far more than the chaoborid found in Peter Lake, C. flavicans. Chaoborus americanus also significantly reduced the dominant copepod, Diaptomus oregonensis, in relation to both the control and the C. flavicans treatment. Chlorophyll a concentration did not differ among treatments, indicating that herbivore responses could not be explained by changes in food levels. Our results show that Chaoborus predation can greatly affect a zooplankton community, especially daphnids.
Resource limitation in a generalist herbivore, the moose Alces alces: ecological constraints on behavioural decisions
Authors: Sæther Bernt-Erik , Andersen Reidar
Published: August 2008

The relationship between foraging behaviour and the time-energy budget of adult moose (Alces alces) cows was studied during the winter in two Norwegian populations. In the study area with lowest food availability, the moose foraged almost exclusively on birch (Betula pubescens) of poor quality (expressed as digestibility). In the other study area with higher food availability, a much more diversified species composition of the diet was found, including several Salix spp., rowan (Sorbus aucuparia), aspen (Populus tremula), and bird cherry (Prunus padus). Large differences in the daily activity of moose were found between the study areas. In the poor food availability area, moose browsed twigs of poor quality and were inactive a greater proportion of the time. They used a smaller area for foraging, but removed a much larger fraction of the available biomass from each browsing site than in the higher food quality study area. No significant difference was found between the study areas in the gross daily dry matter intake rate. A larger amount of feces was defecated in the low quality study area, resulting in a significantly higher net intake of digestible dry matter in the area with high food quality. Thus, because of digestive constraints, the quality of the forage determined the rate of energy gain from foraging. The interaction between moose and their food is therefore strongly dependent on factors that influence the digestibility of forage.
Biology and morphology of immature stages of Meteorus trachynotus Vier. (Hymenoptera: Braconidae)
Authors: Thireau J. C. , Régnière J. , Cloutier C.
Published: August 2008

The immature stages of Meteorus trachynotus Vier., developing in larvae of Choristoneura fumiferana (Clem.), are described. The egg of M. trachynotus is of the stalked type. There are three larval stages. The first instar has a caudal appendage which stops growing in the second instar and is lost when the larva exits from the host in the third instar. Only the first and third instars have sclerotized structures. The head region of the first instar bears a pair of hooklike appendages which are described for the first time. Cephalic sclerites of the last instar larva of other species of Meteorus are compared with those of M. trachynotus. The average duration of immature development at 23 °C was 18 days, the egg stage lasted 3 days, the first, second, and third instars lasted 5, 2.5, and 2.5 days, respectively, and the pupal stage lasted 5 days.
Evaluation of the synlophe of Nematodirus urichi and N. lamae (Trichostrongyloidea) from Mazama americana and camelids (Artiodactyla) in the Neotropics
Authors: Rickard Lora G. , Hoberg Eric P.
Published: August 2008

The synlophes of male and female specimens of Nematodirus urichi and male specimens of Nematodirus lamae are characterized. In the cervical region, at the level of the cervical papillae there were 34 and 42 ridges of variable height in male and female N. urichi, respectively. Ten (male) and 14 (female) ridges extend to the base of the cephalic expansion. In males there are 33 ridges at midbody with the synlophe extending posteriad to within 100 μm of the prebursal papillae. In females there are 38 or 39 ridges at midbody, the synlophe terminating at the level of the vulva. For N. lamae, there were 38–42 ridges in the cervical region; 14 extend to the base of the cephalic expansion. There are 36 ridges at midbody, the synlophe extending posteriad to within 100 μm of the prebursal papillae. An evaluation of parasite morphology and host–parasite biogeography may indicate a close relationship between N. urichi and N. lamae.
The bimodular development of ovarian follicles in cyclic guinea pigs and differences between antral follicles developed at different phases of the cycle
Authors: Hamilton G. S. , Tam W. H.
Published: August 2008

The results of a histological, [3H]thymidine uptake, and autoradiographic study of the cyclic guinea pig ovary suggest that there are two consecutive waves of antral follicle development within each estrous cycle, with the first wave extending from days 2 to 10 and the second wave from days 7 to 16 of the 16-day cycle. The bimodular development is apparently made possible by the continuous daily recruitment of growing follicles from the pool of dormant primordial follicles and by the occurrence of two occasions (days 1–3 and days 6–9) when gonadotropin secretory activity allows some of these follicles to progress into the antral phase of development. The antral follicles of the first wave attain their maximum size (0.5 mm3) on day 9. However, they have disappeared by day 12 and in their place, large atretic follicles and the smaller healthy antral follicles of the second wave have become the most prominent follicular features. On days 14 and 15, the antral follicles of the second wave have grown to 0.5 mm3 themselves, and within the next 24 h their volume increases rapidly by 150% to 1.23 mm3. Extrusion of first polar bodies, vaginal estrus, and ovulation then follow in quick succession. The results indicate that the follicles of the first wave become atretic before the final rapid growth phase and resumption of meiotic division. The absence of the rapid growth phase probably indicates that they have never reached final maturity, nor have they achieved the competence to ovulate in response to gonadotropin stimulation.
The genetic impact of introduced fishes on native species
Authors: Ferguson Moira M.
Published: August 2008

The introduction of nonnative fishes or "exotics" and transplants of fishes outside their geographic range but within the same country is a contentious issue. The effects of these introductions on native fish faunas are well documented and have resulted in legislation controlling future introductions of alien species and management policies based largely on living with past mistakes. However, fish introductions also occur at two more subtle levels: transfers within the range of the species, and introduction of foreign DNA to produce "transgenics." The rationale for transfers is largely typological in that "a fish is a fish," at least as far as any given species might be concerned. Transfers disregard the concept that species are divided into genetically distinct units or "stocks" adapted to their particular environment and that introduction of nonlocal conspecifics can disrupt the genetics and adaptation of local populations. This paper raises some of the major issues and the need to synthesize the concepts, documented cases, and effects.
Vascular supply to bilaterally asymmetric chelae in crustaceans
Authors: Guchardi J. A. , Govind C. K.
Published: August 2008

Blood vessels to the paired hemiganglia and chelae were examined in several crustacean species with bilaterally asymmetric, major and minor, chelae. The network of vessels was qualitatively similar between the paired chelae hemiganglia in Alpheus, Carcinus, Homarus, and Uca. The principal vessel supplying the chela was also similar in size on the two sides, except in the fiddler crab and snapping shrimp where the vessel was larger on the major side. Reversal of chela asymmetry in Alpheus entails a reversal in vessel size denoting plasticity of adult vascular tissue.
Seasonal variation in the testicular cycle of the loggerhead musk turtle, Sternotherus minor minor, from central Florida
Authors: Etchberger Cory R. , Stovall Randall H.
Published: August 2008

Seasonal macroscopic and microscopic changes in the testicular cycle of Sternotherus minor from the southern limit of its range are described, and comparisons are made with the female reproductive cycle from the same population and other populations of Sternotherus from various latitudes. Male S. minor in central Florida reach sexual maturity at three years of age and at least 60 m carapace length. Spermatogenesis in S. minor begins in spring when spermatogonia increase and become abundant. Maximum testicular size is attained during August and September and then decreases until March when testicular mass is minimal. As in other chelonians, the male and female cycles do not peak at the same time. The timing of the testicular cycle of this population is similar to populations of Sternotherus odoratus from different latitudes (Virginia, Alabama) and from other populations of S. minor from Florida, yet differs from a population of S. odoratus from the same latitude. Because this population of S. minor inhabits water of seasonally variable temperature (whereas most S. minor are found in constant temperature situations), photoperiod, and not water temperature, may be the most important proximal determinant of the testicular cycle.
Disturbance behaviors in the spider Uloborus glomosus (Araneae, Uloboridae): possible predator avoidance strategies
Authors: Cushing Paula E. , Opell Brent D.
Published: August 2008

When disturbed, Uloborus glomosus either remain in position at the hub of their orb webs, jump from the web, move to the edge of the web, or shake the web. Juveniles more frequently exhibited moving and jumping responses, whereas the majority of adults jumped from the web or remained in position. Adults with linear stabilimenta tended to shake their webs in the morning and to jump from their webs in the evening. Juveniles with linear stabilimenta shook their webs in the afternoon and evening, whereas those with circular stabilimenta tended to move to the edge of the web or shake the web during all times of day. Adult females with egg-sac chains were usually aligned with the egg sacs and tended to remain in position when disturbed. Both adults and juveniles lacking stabilimenta or egg-sac chains tended to jump from their webs or move to the edge of their webs. Spiders filmed in a natural setting responded to contact by insects. Predatory wasps repeatedly flew near the spiders without eliciting a response. A tethered predatory wasp held above both juveniles and adults in the laboratory also failed to elicit responses from the spiders. The data agree with the hypothesis that moving to the edge of, shaking, and jumping from the web may be predator avoidance strategies elicited by direct contact.
Effects of temperature, photoperiod, and season on the photobehaviour of juvenile Atlantic salmon (Salmo salar)
Authors: Rimmer D. M. , Paim U.
Published: August 2008

The selection of illuminated or shaded areas by juvenile Atlantic salmon (Salmo salar) was examined in relation to temperature and photoperiod. Water temperature had a strong effect on the photoresponse of salmon. Salmon acclimated to 14 °C and a 16-h photophase in summer selected illuminated areas when tested at their acclimation conditions, but rapidly became strongly photonegative while temperature fell to 7 °C. When tested under acclimation conditions of 7 °C and a 16-h photophase during summer, salmon selected shade, but still became distinctly photopositive as temperature increased to 14 °C. Under acclimation conditions of 14 °C and an 8-h photophase during summer, salmon selected illuminated areas, becoming photonegative as temperature fell. Thus, acclimation to photoperiod alone did not exert a clear effect on the photoresponse of summer salmon. If acclimated to 7 °C and an 8-h photophase in winter, salmon selected shade under acclimation conditions and remained photonegative also after temperature increased. Anomalously, after acclimation to 7 °C and an 8-h photophase in summer, salmon were photopositive at 7 °C, but became photonegative and selected shade upon temperature increase, indicating an endogenous seasonal difference not only in their response to thermal stimuli, but also in their susceptibility to acclimation regimes.
Wing folding in pterygote insects, and the oldest Diaphanopterodea from the early Late Carboniferous of West Germany
Authors: Kukalová-Peck Jarmila , Brauckmann Carsten
Published: August 2008

The most primitive known wing articulation and wing folding in the Pterygota occurs in the extinct Palaeoptera the Diaphanopterodea. The oldest Diaphanopterodea Namurodiapha sippelorum n.gen., n.sp. (Namurodiaphidae n.fam.) is described from the early Late Carboniferous (Namurian B) of Hagen-Vorhalle, Ruhr area, West Germany. Unlike other Palaeoptera, the Diaphanopterodea show similar apomorphic venational features and parallel evolutionary trends in wing evolution, as in the unrelated Neoptera. This is explained (i) by convergence caused by the wing folding present in both Neoptera and Diaphanopterodea but absent in the rest of the Palaeoptera, and (ii) by a progressive diminution in size which affected the diaphanopterid and neopterous wing venation in a similar way. The wing articulation and the evolution of wing folding in the earliest known Palaeoptera and Neoptera are examined.
Polyipnus danae n.sp. (Stomiiformes: Sternoptychidae): a new hatchetfish species from the South China Sea
Authors: Harold Antony S.
Published: August 2008

A new species of the marine hatchetfish genus Polyipnus is described, based upon two collections from the South China Sea, western Pacific Ocean. The specimens, collected in 1929 during the circumglobal MV Dana expedition, were not examined in detail until recently. Although Polyipnus danae n.sp. is distinguished from all other species of Polyipnus by a single long spine on each posttemporal bone and 11 or 12 anal photophores, these features and its low gill-raker counts suggest a close relationship to species of the P. laternatus Garman complex, especially to P. aquavitus Baird and P. unispinus Schultz which also occur in Indonesian seas.