bluuebunny/crossref_metadata_2025 huggingface dataset:
The relationship between molecular weight and antifreeze polypeptide activity in marine fish
Authors: Kao Ming H. , Fletcher Garth L. , Wang Nam C. , Hew Choy L.
Published: August 2008

Previous studies have established that the capacity of the glycopeptide antifreezes to depress the freezing temperature of aqueous solutions is positively correlated with molecular weight. The present study was carried out to determine whether a similar correlation existed within the antifreeze peptides. Two approaches were used. Initially, the antifreeze activity (thermal hysteresis) curves of antifreeze peptides from winter flounder, Pseudopleuronectes americanus (molecular weight, 3300), shorthorn sculpin, Myoxocephalus scorpius (molecular weight, 4000), ocean pout, Macrozoarces americanus (molecular weight, 6000), and sea raven, Hemitripterus americanus (molecular weight, 9700), were compared. In the second approach, a more specific comparison was made of two different sized antifreeze peptide components (molecular weights, 2900 and 4000) from the shorthorn sculpin. In both approaches, antifreeze peptide activity was positively correlated with molecular weight and the curve illustrating this relationship suggests that any reduction in molecular weight below 3300 will result in a disproportionate decline in activity. The relatively small antifreeze peptides from the winter flounder and shorthorn sculpin had greater activity than did glycopeptide antifreezes of similar size. However, glycopeptide antifreezes with a molecular weight of 10 000 or more had activities that exceeded that of any known antifreeze peptide. Increases in molecular weight of antifreeze peptides above 4000 resulted in a decline in antifreeze activity per milligram protein. Therefore, in terms of ability to depress the freezing temperature, there appears to be no advantage in evolving large antifreeze peptide molecules.
Avian Haemoproteidae. 22. The haemoproteids of the New World flycatchers, the Tyrannidae
Authors: Bennett Gordon F. , Caines Jennifer R. , Whiteway Madonna
Published: August 2008

The haemoproteids of the Tyrannidae are reviewed and three new species, Haemoproteus circumnuclearis, H. souzalopesi, and H. tyranni are described.
Preparation of dipteran larvae for scanning electron microscopy using a freeze-substitution technique
Authors: Colwell Douglas D. , Kokko Eric G.
Published: August 2008

Difficulties are often encountered in achieving good preservation of dipteran larvae for scanning electron microscopy. Standard fixation methods frequently fail because fixatives do not penetrate the cuticle rapidly, resulting in distortion and generation of artifacts on the surface. A freeze-substitution technique that produces excellent preservation of the larval stages of a wide variety of Diptera is described. The method employs Freon 12 for rapid freezing of the specimens and methanol as the substitution fluid. The technique is simple, inexpensive, and demonstrates a significant improvement in preservation of specimens.
Wounding as an index of aggressive interactions in larval Zygoptera (Odonata)
Authors: Baker Robert L. , Dixon Susan M.
Published: August 2008

We investigated the use of the frequency of wounds to legs and lamellae of larval Zygoptera as an index of aggressive interactions. Criteria for recognizing recent wounds were based on laboratory studies of Ischnura verticalis and Enallagma ebrium larvae with autotomized legs and lamellae; legs and lamellae showing less than 75 and 66% regeneration, respectively, were likely wounded in the preceding instar. Laboratory studies indicated that the frequency of wounds was strongly related to the number of aggressive interactions and that, when smaller larvae were paired with larger larvae, the smaller larvae were more likely to be wounded. Under field conditions, the frequency of wounds of larval I. verticalis and E. ebrium was not correlated with population density but was correlated with dispersal rates. Also, wounded larvae were significantly smaller than nonwounded larvae. The seasonal pattern of wound frequency also suggested that wounds were the result of aggressive interactions. Wounds were more frequent when scarcity of vegetation should have increased the number of encounters between larvae. Frequency of wounding may be a more accurate method of indexing aggressive interactions than density since density estimates are confounded by the quality and quantity of available substrate. The index should prove useful in analysing the effects of behavioural interactions on larval odonate populations.
Observations on the breeding biology of Sabine's Gulls (Xema sabini)
Authors: Abraham Diana M.
Published: August 2008

The breeding biology of Sabine's Gulls (Xema sabini) nesting in a colony with Arctic Terns (Sternaparadisaea) was studied in 1980 at East Bay, Southampton Island, N.W.T. Sabine's Gull nests were initiated over a 1.5-week period, from 23 June to 3 July, and the mean clutch size was 2.77. The mean weight of freshly laid eggs was 22.3 g. Hatching was asynchronous and occurred from 14 to 22 July, following an incubation period of 21 days. Of 53 eggs laid, 44 hatched (83.0%). Chicks showed typical sigmoidal patterns of growth for weight, culmen, and tarsus, and a straight line pattern for ninth primary feather. Growth was rapid, and chicks attained nearly adult proportions by 13 to 15 days of age. The timing and duration of the breeding effort (just over 7 weeks) and the rapid rate of growth of Sabine's Gull chicks are seen as adaptations to the short Arctic summer. The mean internest distance between Sabine's Gulls on the colony was 92.5 m. Nesting was more dense on islands than on the mainland, reflecting the attractiveness of sites least accessible to mammalian predators. An apparent association between breeding Sabine's Gulls and Arctic Terns is reported and two explanations are offered: first, a reliance by Sabine's Gulls on the aggressive behaviour of Arctic Terns or second, coincidence.
Estimating age at independence in small mammals
Authors: Millar John S. , Burkholder Debbie A. L. , Lang Terri L.
Published: August 2008

Age at weaning as indicated by weight change with isolation from the natal nest, age at behavioural independence as indicated by age of leaving the natal nest, and age at nutritional independence as indicated by age at which solid food was eaten were compared between two populations of Peromyscus maniculatus. Age at weaning was much earlier in P. m. nebrascensis (19.2 days) than in P. m. borealis (25.3 days). However, age at nutritional independence was earlier in P. m. borealis than P. m. nebrascensis and age at behavioral independence did not differ between the two populations. We conclude that age at weaning does not reflect true independence and suggest that age at independence should not be based on single developmental events.
The morphological basis of weight-bearing in the scansors of the tokay gecko (Reptilia: Sauria)
Authors: Russell Anthony P.
Published: August 2008

The scansors (subdigital, lamellar, scalelike structures) of gekkonid lizards bear adhesive setae and during locomotion on smooth surfaces must bear the weight of the animal. Thus, the body weight is supported by the integument and relatively large tensile stresses are imposed upon the skin at these times. In order that the relatively delicate integument is not damaged or stripped away from underlying tissues, precise linkages at transition zones occur. The setae themselves consist of material of high tensile strength, the epidermal–dermal junction is an extremely tight bond and the stratum compactum of the dermis provides a direct connection between the epidermis and the lateral digital tendon complex. The latter, in turn, connects directly to the skeleton by way of the metacarpo- or metatarso-phalangeal joint capsules. Additionally, elastin fibrils in the dermis and the collagen fibrils of the dermis and lateral digital tendon network are aligned in parallel with the long axis of each digit and are arranged to permit controlled distortion of the exposed scansorial surfaces.
Kudoa thyrsitis (Gilchrist) (Myxosporea: Multivalvulida) in coho salmon, Oncorhynchus kisutch (Walbaum)
Authors: Kabata Z. , Whitaker D. J. , Bagshaw J. W.
Published: August 2008

An unusual case of infection of coho salmon, Oncorhynchus kisutch (Walbaum), in British Columbia, Canada, with a myxosporean Kudoa thyrsitis (Gilchrist) is described. This first report of Kudoa parasitizing a member of the genus Oncorhynchus is interesting also because of the unusual site of Kudoa in the fish, the cardiac muscle.
Black fly host location: a review
Authors: Sutcliffe James F.
Published: August 2008

Host location in black flies (Diptera: Simuliidae) is treated broadly as any event or action in the insect's adult life that (i) contributes to its ability to respond to a host, (ii) enhances its probability of contacting a host, or (iii) brings it into closer physical proximity to its ultimate goal, a blood meal. Host location in this broad sense is discussed under the following three headings. (i) Postemergence activities, such as nectar-feeding, mating, dispersal, and migration. These prepare the insect behaviourally and physiologically and bring it into the host's habitat, (ii) Host-searching, nonoriented flight driven by appetitive internal forces, namely endogenous activity rhythms and hunger. The host search maximizes the probability of contact with a host while minimizing energy output. (iii) Host location proper, oriented by external stimuli interacting with internal programmes of behaviour. Host location (sensu stricto) consists of long-, middle-, and short-range phases as well as postlanding activities, and is driven by olfactory, visual, anemotactic, optomotor, thermal, and gustatory stimuli. The paucity of information related to black flies for some of these topics is partially compensated for through extensive referral to the literature on similar problems in other insects.
Renal function and acid-base balance in the toad Bufo marinus during short-term dehydration
Authors: Tufts B. L. , Toews D. P.
Published: August 2008

Specimens of Bufo marinus (L.) were cannulated in both ureters to partition between the regulatory contributions of the kidney and urinary bladder. These bladder-bypassed animals were then exposed to 10 h of dehydration in air and renal function and acid–base balance were assessed. The results indicated that the kidney showed an almost immediate response to dehydration which consisted of a large glomerular and smaller tubular component. Bypassing and emptying of the bladder and the removal of the ambient water had no effect on the animal's ability to maintain normal acid–base balance.
Hydrodynamics and behaviour of Simuliidae larvae (Diptera)
Authors: Chance M. M. , Craig D. A.
Published: August 2008

Detailed water flow around larvae of Simulium vittatum Zett. (sibling IS-7) was investigated using flow tanks, aluminium flakes, pigment, still photography, cinematography, and video recordings. Angle of deflection of a larva from the vertical has a hyperbolic relationship to water velocity. Velocity profiles around larvae show that the body is in the boundary layer. Frontal area of the body decreases as velocity increases. Disturbed larvae exhibit "avoidance reaction" and pull the body into the lower boundary layer. Longitudinal twisting and yawing of the larval body places one labral fan closer to the substrate, the other near the top of the boundary layer. Models and live larvae were used to demonstrate the basic hydrodynamic phenomenon of downstream paired vortices. Body shape and feeding stance result in one of the vortices remaining in the lower boundary layer. The other rises up the downstream side of the body, passes through the lower fan, then forms a von Karman trail of detaching vortices. This vortex entrains particulate matter from the substrate, which larvae then filter. Discharge of water into this upper vortex remains constant at various velocities and only water between the substrate and top of the posterior abdomen is incorporated into it. The upper fan filters water only from the top of the boundary layer. Formation of vortices probably influences larval microdistribution and filter feeding. Larvae positioned side by side across the flow mutually influence flow between them, thus enhancing feeding. Larvae downstream of one another may use information from the von Karman trail of vortices to position themselves advantageously.
Response of stream benthos and drift to fine sediment deposition versus transport
Authors: Culp Joseph M. , Wrona Frederick J. , Davies Ronald W.
Published: August 2008

Field experiments were conducted to investigate the responses of benthic macroinvertebrate communities to experimental additions of fine sediments into riffles having a flow with either low tractive force so the sediments were deposited or sufficient tractive force to transport the added sediments. Sediment deposition had no measurable impact on most taxa, the only negative effects being significantly higher drift rates and lower benthic densities for Paraleptophlebia. Sediment transport by saltation created a physical disturbance that reduced total benthic densities by >50% in 24 h and significantly influenced macroinvertebrate community composition. Changes in the benthic community were the result of catastrophic drift, and distinct immediate and delayed responses of diurnal drift to the saltating sediments were evident. Taxa with the immediate drift response resided predominantly at the substrate surface and were instantaneously exposed to scouring as sediments were added. Macroinvertebrates showing the delayed response initially avoided the saltating sediments because of their deeper distribution, but an apparent diel shift in vertical distribution exposed these taxa to saltating sediments 6–9 h after sediment additions. Thus, even when tractive forces were insufficient to suspend fine sediments, catastrophic drift was initiated by fine sediments that slid and bounced along the surface of the stony substrate. Sediment saltation, therefore, has the potential to act as a community-level disturbance early in the storm hydrograph or at lower discharge magnitudes than required to suspend sediments.
La gestion des acides aminés aromatiques chez les Lépidoptères
Authors: Rahbé Y. , Bonnot G.
Published: August 2008

Lepidoptera, like other insects (sensu stricto, i.e., without their possible symbionts), require an exogenous input of aromatic nuclei. Phenylalanine must thus be considered as an essential amino acid; however, the most important aromatic metabolite is tyrosine. In addition to being incorporated into proteins, tyrosine goes through specific stages that are either transitory (storage or mobilization forms) or terminal in some of the major functional pathways in insects (generally through previous hydroxylation into catecholic substances). Some polypeptids incorporate tyrosyl residues either for structural or for metabolic storage purposes. Studies on insect neurochemistry have revealed the existence of neuroactive phenolamines and catecholamines. Although the chemistry of melanin formation is important in understanding certain physiological phenomena that affect both larval and adult Lepidoptera, it has never been studied in detail because of its complexity. Biochemical studies of sclerotization, which have been extensive during the past 20 years, have recently revealed several specific lepidopteran characteristics. Lepidoptera use a specific transitory storage form of tyrosine, β-D-glycopyranosyl-O-tyrosine, and the process of N-acylation, which affects dopamine at the time of nymphal ecdysis, leads to the formation of N-β-alanyldopamine instead of N-acetyldopamine as was shown by classic studies on Diptera. Moreover, differential activation of these metabolic pathways in the course of ontogenesis brings about a marked temporal compartmentalization. Many phases of tyrosine biochemistry are thus recognized in the development of Lepidoptera.[Journal translation]
Population dynamics and litter size of the montane vole, Microtus montanus
Authors: Pinter Aelita J.
Published: August 2008

Population dynamics of the montane vole, Microtus montanus, in northwestern Wyoming have been studied since 1969. Four peaks and four troughs in population density and four peaks and four troughs in litter size have been documented to date. There is a significant correlation between the peaks and the troughs of the two parameters: the peaks and the troughs in litter size precede the peaks and troughs in population density by 1 year. There were only two exceptions to this relationship in 15 years. Changes in litter size are, therefore, a useful predictor of the direction, but not, however, of the magnitude of the change in population density in the ensuing year. Litter size was also correlated with population cycle phase, suggesting the existence of qualitative differences between populations from different cycle phases. However, the factors that underlie the predictive value of litter size and the correlation of litter size with cycle phase remain unknown.
Ultrastructure of the spermatozoon of the cestode Duthiersia fimbriata Diesing, 1854 (Pseudophyllidea, Diphyllobothriidae)
Authors: Justine Jean-Lou
Published: August 2008

The spermatozoon of Duthiersia fimbriata Diesing, 1854 (collected from the varanid lizard Varanus niloticus Linnaeus, in Senegal) is described. The spermatozoon contains two parallel axonemes showing the 9 + "1" flatworm pattern, longitudinal cortical microtubules, and the nucleus. A mitochondrion is absent. A region of the spermatozoon contains a single axoneme. This region is flanked along part of its length by a helical flange ("corps en crête"), which is reported here for the first time in a pseudophyllidean cestode. Comparison of bibliographical data indicates that this structure is of little value for phyletic studies.
Parasites of trout from the Au Sable River, Michigan, with emphasis on the population biology of Cystidicoloides tenuissima
Authors: Muzzall Patrick M.
Published: August 2008

Trout (212 brook trout, Salvelinus fontinalis, and 231 brown trout, Salmo trutta, Salmonidae) were collected from the Au Sable River, Michigan, and examined for parasites between April 1982 and July 1984. One hundred seventy-six brook trout and 153 brown trout were infected with at least one of the following parasites: Crepidostomum cooperi, Neascus sp., Eubothrium sp., Proteocephalus sp., Truttaedacnitis sp., Cystidicoloides tenuissima, Rhabdochona canadensis, Spinitectus gracilis, Epistylis sp., Trichodina sp., and Salmincola edwardsii. Cystidicoloides tenuissima, the most common and abundant species, did not exhibit a pronounced seasonal pattern in prevalence; mean intensity, however, was highest in July 1982, 1983, and 1984 in both trout species. The intensity of C. tenuissima increased as trout became older and then decreased in brook and brown trout 3 and 4 years of age, respectively. Data on the seasonality of S. gracilis and C. cooperi infecting trout are also presented. The muscles of trout were negative for parasites. Over 500 mayfly nymphs (Ephemeroptera) representing at least seven species were examined for parasites. Cystidicoloides tenuissima infected Ephemera simulans. Crepidostomum sp., Rhabdochona sp., and S. gracilis occurred in Hexagenia limbata.
Den digging and pup care in captive coyotes (Canis latrans)
Authors: Ryon Jenny
Published: August 2008

Captive coyotes were studied for den digging and use (N = 10) and pup care activities (N = 4 adults and 2 yearlings). Method of construction and configuration of dens is described. Pup care activities of individual pack members are documented, including: den tending, ano-genital grooming, nursing, feeding solid food, transferring pups between dens, and alarm barking. It is suggested that endogenous factors be considered in addition to environmental causes for the phenomenon of multiple den use and frequent transferral of pups which may have evolved as a method of decreasing the risks of pup predation.
The seasonal community structure and drift of microcrustaceans in Valley Creek, Minnesota
Authors: Shiozawa Dennis K.
Published: August 2008

Microcrustaceans represent a poorly known component of stream systems. This study examined the seasonal abundance of copepods and cladocerans found in Valley Creek, Washington County, Minnesota. Both benthic densities as well as drift rates were quantified. A total of 16 species was collected in quantitative benthic samples and two additional species occurred in drift samples. The Valley Creek microcrustaceans could be classified into two general groups, those residing in depositional stream habitats similar to a lake or pond littoral and favoring an epibenthic lifestyle, and those found in more erosional habitats where a hyporheic lifestyle is more likely. The microcrustacean community also demonstrated a distinct seasonality with peak abundance in the spring and early summer. Sediment size compositon also demonstrated a seasonal change but detrital composition did not. Microcrustacean drift generally paralleled changes in benthic density but in several cases it tended to lag behind the changes in the benthos. This lag could be due to a seasonal siltation of the sediments, which would compress the habitat volume available to interstitial meiofaunal elements.
Revision of sea anemone genus Epiactis (Coelenterata: Actiniaria) on the Pacific coast of North America, with descriptions of two new brooding species
Authors: Fautin Daphne Gail , Chia Fu-Shiang
Published: August 2008

Two new species of the actiniid genus Epiactis, Epiactis lisbethae and Epiactis fernaldi, are described from the intertidal zone of the San Juan Islands, Washington, U.S.A. The sea anemone genus Cnidopus is synonymized with Epiactis, and its type species, C. ritteri, is restored to the genus in which it was originally described. Thus, four species of Epiactis are known on the Pacific coast of North America: external brooders E. prolifera (type species of the genus) and E. lisbethae, which differ in sexuality and brooding periodicity; and internal brooders E. ritteri and E. fernaldi, which differ in cnidae, sexuality, and histology. These bring the number of nominal species in the genus Epiactis to 19.
Diet selection in Arctic lemmings (Lemmus sibiricus and Dicrostonyx groenlandicus): forage availability and natural diets
Authors: Rodgers Arthur R. , Lewis Martin C.
Published: August 2008

We describe forage availability and diets of the lemmings Lemmus sibiricus and Dicrostonyx groenlandicus at Igloolik Island, Northwest Territories. Summer and winter diets of Dicrostonyx were dominated by the evergreen shrub Dryas integrifolia and supplemented by the deciduous shrub Salix arctica. Lemmus ate mainly graminoids and some mosses in summer but the reverse in winter. In both species, winter diets were similar in different habitats. Comparison with diets of lemmings in Alaska show sufficient similarity to explain the synchrony of population fluctuations over wide geographical areas. Site-specific differences occur, however, and these are accounted for by an examination of the diet selection process in each species. These differences have important implications for the demography of lemmings at different sites.
Pituitary gonadotropin contents and ultrastructure of the gonadotrops in the African catfish Clarias gariepinus during the annual cycle in a natural habitat
Authors: Peute J. , Zandbergen M. A. , Goos H. J. Th. , Leeuw R. de , Pinkas R. , Viveen W. J. A. R. , Oordt P. G. W. J. van
Published: August 2008

Over a period of 1 year, male and female specimens of a natural population of African catfish, Clarias gariepinus, were collected monthly at locations in northern Israel. Both the ultrastructural appearance of the gonadotrops and the pituitary gonadotropin content in males and females showed cyclical changes, which paralleled alterations in the reproductive cycle. In summer, during the breeding period, the gonadotrops were large and fully granulated, and pituitary gonadotropin reached maximum levels. After spawning, the resting period begins, with an increasing number of fusion products of secretory granules and globules in the gonadotrops, probably indicating a breakdown of hormone storage. This was followed by the appearance of residual bodies, cell shrinkage, and a considerable drop in pituitary gonadotropin content. In late winter and early spring, during gonadal recrudescence, the gonadotrops redeveloped, i.e., they increased in size and granulation, and at the same time the pituitary gonadotropin content augmented. This reproductive cycle will permit induced spawning and artificial propagation of African catfish from March till September. However, keeping the catfish at favourable feeding and temperature conditions may also permit the gonadotrops to produce gonadotropin continuously, thus providing the possibility of complete gametogenesis and of obtaining viable eggs and healthy larvae throughout the year.
Differential temperature sensitivity of two cladoceran species to resource variation during a blue-green algal bloom
Authors: Threlkeld Stephen T.
Published: August 2008

The sensitivity of life-table parameters of two cladoceran zooplankton to slight, natural variations in temperature was determined during the onset of a midsummer blue-green algal bloom in a large turbid reservoir (Lake Texoma, Oklahoma, Texas). Prior to the onset of blue-green algae, cohorts of Ceriodaphnia lacustris incubated at ambient epilimnion temperatures (27–30 °C) had higher individual somatic and population growth rates, an earlier age at first reproduction, and shorter life-spans than cohorts incubated at a constant 25 °C. As blue-green algae became abundant, Ceriodaphnia growth rates were reduced more dramatically at ambient temperatures than at 25 °C, suggesting that a temperature–resource interaction was important to determination of somatic growth rate, age of first reproduction, and population growth rate. Ceriodaphnia populations declined in Lake Texoma as blue-green algae became abundant. Diaphanosoma leuchtenbergianum, which was abundant throughout the period of blue-green algal dominance, did not show the temperature–resource interaction found for Ceriodaphnia. Temperature–resource interactions have been hypothesized to determine seasonal change in zooplankton community structure; this study provides experimental evidence of demographic consequences in natural populations of one kind of common temperature–resource interaction.
Filaroides (Parafilaroides) hispidus n.sp. (Nematoda: Metastrongyloidea) from the lungs of the ringed seal, Phoca hispida (Phocidae), from the Beaufort Sea, Canada
Authors: Kennedy Murray J.
Published: August 2008

Filaroides (Parafilaroides) hispidus n.sp. from the ringed seal, Phoca hispida, from the Beaufort Sea can be distinguished from all other Filaroides (Parafilaroides) species by its small size, the presence of longer spicules, and, except for F. (P.) hydrurgae, a longer gubernaculum.
Antifreeze peptides confer freezing resistance to fish
Authors: Fletcher Garth L. , Kao Ming H. , Fourney Ron M.
Published: August 2008

It has been widely accepted that plasma antifreeze proteins are directly responsible for the ability of many marine teleosts to survive in ice-laden seawater. However, there appears to be no direct experimental evidence to indicate that this assumption is correct. In the present study winter flounder (Pseudopleuronectes americanus) showed seasonal changes in freezing resistance that were quantitatively the same as the seasonal changes in plasma antifreeze protein levels. Moreover, when winter flounder antifreeze proteins were injected into rainbow trout (Salmo gairdneri) (a species that does not normally possess antifreeze proteins) they increased the freezing resistance of the trout in direct proportion to plasma antifreeze protein levels attained. These studies indicate that antifreeze proteins are directly responsible for the ability of many marine teleosts to survive icy seawater at temperatures below the colligative freezing points of their blood. There appears to be no requirement for species-specific antifreeze protein receptors in the fish in order for them to act.
Lipid content and energy expenditure in the spawning migration of alewife (Alosa pseudoharengus) and blueback herring (Alosa aestivalis)
Authors: Crawford Robert H. , Cusack R. Roland , Parlee Timothy R.
Published: August 2008

For the alewife (Alosa pseudoharengus) and blueback herring (Alosa aestivalis) total lipid content was neither size nor sex specific. The lipid content of alewife and blueback herring from the LaHave River, Nova Scotia, was similar at 7.6 and 7.0%, respectively. However, in samples from the Margaree River there was a significant difference in lipid content between alewife and blueback herring (7.8% vs. 5.4%, respectively). The difference appeared to be a consequence of water temperature since late migrants of both species had a significantly lower lipid content. For alewife migration in the LaHave River, a distance of 31 km, lipid content declined by 22%, whereas in the Margaree River lipid loss was 18% over 32 km. Lipid content was also dependent on reproductive maturity, with lipid levels of 14.4, 8.7, and 5.4% in immature, prespawning, and spent alewife from site 1 on the Margaree River. Immature fish were characterized by a very high lipid content associated with the visceral organs. Protein utilization was not evident in the prespawning migration of alewife from the LaHave River. Based on lipid depletion the migration energetics of alewife in the two rivers were similar at 21.68 and 18.53 kJ∙kg−1∙km−1 in the LaHave and Margaree Rivers, respectively.
Numerical responses of red-winged blackbird populations to changes in regional land-use patterns
Authors: Clark Robert G. , Weatherhead Patrick J. , Greenwood Hamilton , Titman Rodger D.
Published: August 2008

The red-winged blackbird (Agelaius phoeniceus) population in southwestern Quebec more than doubled between 1966 and 1981, apparently in response to increased corn production. In southwestern Ontario less pronounced increases in blackbirds and corn production also occurred. Although larger blackbird populations have been responsible for greater crop damage, it is the waste corn left in fields by mechanical harvesters that supports the increased blackbird population. The increased availability of waste corn during the spring and summer (breeding season) was likely most important in allowing the blackbird population to grow. This conclusion is supported by our census of blackbird populations in 38 counties in southwestern Quebec during the breeding season, which indicated a strong positive correlation between blackbird abundance and corn production in a county. Although corn production explains much variation in the size of blackbird populations, other factors such as the availability of breeding habitat and the spatial distribution of habitats (landscape heterogeneity) may be responsible for additional variation.
Relationship between cranial damage attributable to Skrjabingylus (Nematoda) and braincase capacity in the striped skunk (Mephitis mephitis)
Authors: Maldonado Jesus E. , Kirkland Jr. Gordon L.
Published: August 2008

Cleaned and dried crania of striped skunks (Mephitis mephitis), with and without external lesions attributable to Skrjabingylus spp. (Nematoda, Metastrongyloidea), were examined to determine the relationship between braincase capacity in M. mephitis and cranial damage attributable to Skrjabingylus spp. The rate of increase in braincase or cranial capacity as a function of skull size was significantly less in crania evincing Skrjabingylus lesions. In general, braincase capacity tended to be smaller in specimens evincing cranial lesions than in comparable-sized skulls lacking lesions. In a sample of 16 freshly killed M. mephitis, 7 of 8 specimens that harbored adult Skrjabingylus chitwoodorum evinced both external lesions and macroscopic damage to the roof of the braincase, whereas none of 8 specimens free of adult S. chitwoodorum had any external or internal cranial lesions. These results support the hypothesis that downwarping of the cranial roof and corresponding reduction in braincase capacity in M. mephitis are associated with Skrjabingylus infections. Such changes in the cranium could explain, at least in part, behavioral aberrations in M. mephitis infected with Skrjabingylus spp.
Plicatotheca anitae, a new genus and species of thecate hydroid from Bermuda and South Africa
Authors: Calder Dale R. , Vervoort W.
Published: August 2008

Plicatotheca anitae, n.gen., n.sp. (Hydrozoa: Phialellidae) is described from material collected on coral rubble at a depth of 60–90 m off Bermuda. The species has previously been reported from a depth of 430 m off Durban, South Africa, as Opercularella sp. Plicatotheca is distinguishable from the related genera Opercularella, Dipleuron, and Phialella in having linguiform opercular facets that do not close tightly over the hydrotheca when folded. Plicatotheca anitae resembles Opercularella denticulata (Clarke, 1907), but differs in both colony form and opercular structure. Gonophores of P. anitae are presently unknown.
17α,20β-Dihydroxy-4-pregnen-3-one: a steroidal primer pheromone increasing milt volume in the goldfish, Carassius auratus
Authors: Stacey N. E. , Sorensen P. W.
Published: August 2008

The volume of milt that could be stripped from male goldfish, Carassius auratus, increased dramatically when fish were exposed overnight to water with concentrations of 17α,20β-dihydroxy-4-pregnen-3-one (17,20P) as low as 10−10 M. A variety of free steroids (pregnenolone, androstenedione, testosterone, 11-ketotestosterone, 17β-estradiol) and glucuronated steroids (etiocholanolone glucuronide, testosterone glucuronide, 17β-estradiol glucuronide), suggested by others to function as pheromones in fish, failed to increase milt volume at a concentration of 5 × 10−9 M. The milt response appears to be specific to 17,20P and progesterone precursors (17α-hydroxyprogesterone, progesterone), but is most sensitive to 17.20P. Because bilateral section of the olfactory tracts completely blocked the milt response to 17.20P, it is believed to be a pheromone. Selective sectioning of the lateral and medial subdivisions of the olfactory tracts demonstrated that the milt response to 17,20P is dependent on the medial tract. Increases in milt in response to 17,20P are not affected by interaction with conspecifics; exposure to 17,20P induced equivalent responses in males held in isolation, paired with a male, or paired with a female. It is proposed that 17,20P, which is produced during oocyte final maturation in the female, is a "primer" pheromone released to the water and that it increases milt volume in the male. This effect is discussed in relation to releaser pheromone effects previously demonstrated in goldfish.
Revision of the genus Desportesius Chabaud and Campana, 1949 (Nematoda: Acuarioidea) mainly from the gizzard of ciconiform birds
Authors: Wong P. L. , Anderson R. C.
Published: August 2008

Desportesius Chabaud and Campana, 1949 is revised. Eight species are recognized: D. brevicaudatus (Dujardin, 1845), D. bubulcusi (Kumar and Gupta, 1979), D. equispiculatus (Wu and Liu, 1943), D. invaginatus (Linstow, 1901), D. longevaginatus (Molin, 1860), D. orientalis (Wu, 1933), D. sagittatus (Rudolphi, 1809), and D. triaenucha (Wright, 1879). Desportesius spinulatus Chabaud and Campana, 1949, D. morneti Gretillat and Morel, 1961, D. cramae Sharma, 1973, D. nigeri Gupta and Kazim, 1978, and D. ibisi Naidu, 1981 are considered synonyms of the type species, D. invaginatus. Desportesius canadensis is regarded as a synonym of D. triaenucha. Three species are regarded as species inquirendae: Synhimantus ardeai Agrawal, 1965, D. groffi (Li, 1934), and D. raillieti (Skrjabin, 1924). Desportesius invaginatus, D. brevicaudatus, D. triaenucha, and D. longevaginatus are redescribed and a key to species is provided. Although Desportesius and Syncuaria Gilbert, 1927 have dissimilar cordon arrangements they may be closely related on the basis of the following shared characters: (i) monodelphy, (ii) vulva located immediately anterior to anus, (iii) highly inflated male caudal alae, (iv) preanal caudal papillae located immediately anterior to anus, and (v) short male and female tails.
Foraging range in mice and voles: the role of risk
Authors: Anderson Paul K.
Published: August 2008

The significance of risk assessment in determining the boundaries of foraging ranges of deer mice and voles was examined by comparing the distances to which resident animals were willing to follow shifting feeding stations providing equal rewards beyond their previous foraging ranges in an area with abundant cover (forest), and in one where cover was lacking (frozen lake surface). Previous foraging ranges were estimated on the basis of livetrapping and the "rediscovery distances" for the moving stations. In three experiments the distance at which animals stopped visiting the stations ("giving-up distance") averaged 3.3 times farther where cover was abundant (forest) than where it was absent (lake). In a fourth experiment, reduction of supplementary food available within the original ranges extended the giving-up distance where cover was present but had relatively little effect on giving-up distance and almost no effect on rediscovery distance where cover was absent. Supplying cover more than tripled giving-up distances on the lake. The distance at which boxes were visited was affected by snowfall, ambient temperature, food supply, and availability of cover. Results emphasize the importance of risk assessment in defining foraging range, and suggest that hoarding permits choice among energy maximization and time minimization strategies.
Effects of temperature on triiodothyronine plasma levels, kinetics, and hepatocyte nuclear binding in rainbow trout, Salmo gairdneri
Authors: Eales J. G. , Kraak G. Van Der , Chang J. P. , Omeljaniuk R. J.
Published: August 2008

Plasma levels of 3,5,3′-triiodo-L-thyronine (T3), plasma T3 kinetics, and properties of in vivo T3 binding to saturable hepatocyte nuclear sites were studied in fed immature rainbow trout maintained at 12 °C and then held for up to 14 d at 5, 11–12, or 19 °C. Elevation (19 °C) or depression (5 °C) of plasma T3 occurred during the first 3 h following abrupt transfer from 11 °C, but from 12 h to 7 d, plasma T3 did not differ significantly among the three temperatures. In contrast, the plasma T3 degradation rate increased fourfold from 5 to 19 °C largely because of an increased fractional rate of turnover of the plasma T3 pool. Outer-ring deiodination of T3 was negligible at 5 and 12 °C and slight at 19 °C. Temperature did not influence the proportion of [125I]T3 lost via the enterohepatic route. Uptake of [125I]T3 into the liver and liver nuclear fraction was most rapid at 19 °C, intermediate at 12 °C, and least rapid at 5 °C. Saturable nuclear binding of [125I]T3 occurred at all temperatures. The apparent affinity of T3 for hepatic nuclear sites was similar at 12 and 19 °C but lower at 5 °C; the apparent site capacity underwent no significant change with temperature. In conclusion, over the range of 5 to 19 °C there are marked increases in plasma T3 clearance, rate of T3 uptake from plasma to liver, and rate of T3 uptake by the liver nuclear fraction, but relatively small changes in plasma T3 level, proportion of T3 excreted via the enterohepatic route, and properties of the saturable T3-binding nuclear sites.
Kinetics of lactate dehydrogenase from heart and white muscle of ocean pout: a single isozyme system
Authors: Stewart John M. , Driedzic William R.
Published: August 2008

Heart and white skeletal muscle of ocean pout (Macrozoarces americanus) express only a single lactate dehydrogenase isozyme based on electrophoretic and immunological analysis. The enzyme has been partially purified and its kinetic properties elucidated in both the pyruvate reductase and lactate oxidase directions. Km values and responses to changing pH catagorize the enzyme as a classical skeletal muscle type lactate dehydrogenase. The kinetic parameters are assessed with respect to known in situ carbon flux rates through this locus. It is concluded that the enzyme data per se provide little insight into either the dominant direction or the net maximal rate of carbon flow.
Interactions between the scelionid egg parasitoid Tiphodytes gerriphagus (Hymenoptera) and its gerrid hosts (Heteroptera)
Authors: Spence John R.
Published: August 2008

Tiphodytes gerriphagus parasitized eggs of five Gerris and two Limnoporus species in the laboratory and the parasitoids were reared from field-collected eggs of G. buenoi, G. comatus, G. pingreensis, L. dissortis, and L. notabilis. Eggs of G. buenoi and L. dissortis were parasitized over about 80% of development. Wasps preferred eggs of G. buenoi over those of L. dissortis, which were larger but covered by a jelly coat. However, under field conditions, eggs of L. dissortis laid at the water surface were parasitized more than submersed eggs of Gerris species. Host size (= species) had no apparent effect on adult life-span but affected the body length of adult parasitoids. Size of females was affected more than that of males and lifetime fecudity also varied with host size. Parasitoids laid most of their eggs during the first 4 days after emergence, averaging 8–11 parasitized hosts per day. Tiphodytes gerriphagus was reared from eggs of Limnoporus collected throughout western Canada. Rates of parasitism peaked just after egg production by L. dissortis, suggesting selection for early oviposition by gerrids. Most Limnoporus populations were heavily parasitized by late summer, but in some temporary or newly created habitats, rates of parasitism were lower. Growth of the parasitoid population at a new habitat was slower than at nearby ponds with large resident wasp and gerrid populations, and the lower parasitoid abundance was associated with greater production of L. dissortis. Adults of T. gerriphagus appear to overwinter in gerrid eggs at the bottom of ponds. At temporary sites, wasps may fail to survive the winter and recolonize more slowly than Limnoporus. Interaction with parasitoids may explain the patchy nature of L. dissortis distribution and its restriction to temporary habitats. Presence of T. gerriphagus may also affect the outcome of competitive interactions among gerrid species.
Fine structure of integumental glands in the labial palp of adult Graphoderus occidentalis Horn (Coleoptera: Dytiscidae)
Authors: Leung E. S. , Zacharuk R. Y.
Published: August 2008

The terminal segment of the labial palp of the diving water beetle Graphoderus occidentalis contains numerous integumental glands. Each secretory unit is composed of three cells: a long, thin distal duct cell; a long, wider proximal duct cell; and a bulbous basal gland cell. A cuticular duct, which opens through a pore at the surface, extends centrally through all three cells, after penetrating the cuticle and underlying epidermal layer. The proximal duct cell is joined to the distal duct cell and the gland cell by desmosomes and septate junctions between their interdigitated membranes. The distal duct cell is joined to adjacent epidermal cells similarly. The distal duct cell has a small nucleus and few cytoplasmic inclusions. The proximal duct cell extends numerous microvilli centrally, from which packed epicuticular filaments extend perpendicularly to the central duct. It has a large nucleus, small mitochondria, smooth tubular endoplasmic reticulum, and scattered ribosomes. The gland cell has very abundant rough endoplasmic reticulum, Golgi complexes, secretory granules and globules, and a large nucleus with a prominent nucleolus. In this cell the duct, which terminates in a reticular end apparatus, is surrounded by a thick layer of tightly packed microvilli. The secretory products are positive for periodic acid – Schiff s, Alcian Blue, and Aldehyde Fuchsin, suggesting a mucopolysaccharide nature.
The role of seasonality in vole cycles
Authors: Ostfeld Richard S. , Tamarin Robert H.
Published: August 2008

We examined the assertion that seasonal fluctuations in food availability are necessary for vole cycles to take place by studying the dynamics of a California vole (Microtus californicus) population inhabiting a relatively aseasonal environment. That population was one of the most stable (noncyclic) microtine populations yet described. Reproduction was comparatively aseasonal but appeared to be suppressed at high population density. We suggest that the role of seasonality in vole population fluctuations deserves further study.
IMPROVEMENT IN MECHANICAL PERFORMANCE OF LOW-MODULUS β-Ti-Nb-Ta-Zr SYSTEM ALLOYS BY MICROSTRUCTURAL CONTROL VIA THERMOMECHANICAL PROCESSING
Authors: NIINOMI M.
Published: August 2008

Mechanical performance parameters such as the fatigue strength, tensile strength, ductility and Young's modulus of newly developed Ti -29 Nb -13 Ta -4.6 Zr , referred to as TNTZ, can be improved considerably by microstructural control via thermomechanical processing. Thermomechanical processing including severe cold wire drawing can generate functionalities such as super elasticity in TNTZ. The abovementioned improvement in the mechanical performance and functionality of TNTZ is associated with its nanosize structure. The cytotoxicity of TNTZ is very low and equivalent to that of pure titanium. It is expected that TNTZ will be used as a structural biomaterial.
EVOLUTION OF NANO GRAINS IN A BULKY Cu-Zn ALLOY ENHANCED BY MECHANICAL TWINNING DURING MULTI-DIRECTIONAL FORGING
Authors: MIURA H. , NAKAO Y. , SAKAI T.
Published: August 2008

A bulky Cu - Zn alloy was multi-directionally forged (MDFed) at 77 K and 300 K up to a cumulative strain of 6.0 at maximum. With increasing strain, the evolved substructure changed gradually to uniform ultra fine grains. The tendency of the microstructural evolution and its mechanism depended strongly on the MDF temperature. Mechanical twins accelerated the finer grain fragmentation by subdivision of the grains and by intersection of the twins themselves due to MDF. Twinning appeared more frequently and uniformly at 77 K than at 300 K. The average grain size obtained at a cumulative strain of 6.0 was about 17 nm at 77 K and 26 nm at 300 K. The evolution of the microstructure accompanied by mechanical twinning is precisely investigated.
IMPROVEMENT IN MECHANICAL PROPERTIES OF Fe-Ni-Mn MARAGING STEEL BY HEAVY COLD ROLLING
Authors: NILI-AHMADABADI M. , SHIRAZI H. , FATEHI A. , HOSSEIN-NEDJAD S.
Published: August 2008

Maraging steels are a group of martensitic steels possessing ultra high strength along with good fracture toughness. Conventional 18 wt.% Ni maraging steels are very costly in part because of expensive alloying elements such as Ni and Co . Replacement of Ni by cheaper elements like Mn has been studied by many researchers. Fe – Ni – Mn ternary alloys show good age hardenability formation of nanometer sized intermetallic precipitates such as f.c.t. θ- NiMn during aging. These alloys are ductile in the solution annealed condition but suffer from severe embrittlement after aging by intergranular fracture along prior austenite grain boundaries (PAGBs). Discontinuous coarsening of grain boundary precipitates was found as the main source of embrittlement. In this paper the effect of cold rolling on the mechanical properties of Fe -10 Ni -7 Mn steel was investigated. Cold rolling for 20%, 40%, 60%, 80% and 90% were carried out on a solution annealed material with subsequent aging at 753 K. Improvements in the tensile properties of the as-deformed and aged alloys were found. Substantial improvement is found at thickness reductions larger than 60%, where severe plastic deformation and ultrafine grain formation are realized.