bluuebunny/crossref_metadata_2025 huggingface dataset:
Thermal preference in relation to salinity in the threespine stickleback, Gasterosteus aculeatus L., with an interpretation of its significance
Authors: Garside E. T. , Heinze D. G. , Barbour S. E.
Published: August 2008

Thermal preferences were determined in spacious thermal gradients of fresh water and sea water (32‰ salinity (S))for acclimations of 5, 15, and 25 °C in sea water, for samples of threespine stickleback Gasterosteus aculeatus L. Preferred temperatures increased through acclimations of 5–25 °C, with those for the freshwater tests being about 2 °C lower at each acclimation. Final preferenda were 16 and 18 °C for freshwater tests and seawater tests, respectively. The final preferendum in such haloplastic species is defined as the highest obtainable preferendum that equals acclimation temperature. A later series of disjunct preference determinations in approximately isosmotic water (10.5‰ S) for subjects acclimated to 7, 15, and 20 °C yielded mean values of 17.7, 18.2, and 18.7 °C, respectively. A final preferendum has not been designated since the samples were of separate origins. A parallel exists between these responses and the response of this and other haloplastic species in the determination of upper lethal temperatures. The immediate cause appears to be differentials in metabolic loading occasioned by l stresses.
The life history, growth, and age structure of Nephelopsis obscura Verrill, 1872 (Hirudinoidea) in Alberta
Authors: Davies Ronald W. , Everett Roger P.
Published: August 2008

Two generations of Nephelopsis obscura were produced annually in the spring and in the late summer. The spring generation was the progeny of the heavier elements of the previous year's spring generation and of the late-summer generation produced 2 years previously. The late-summer generation was produced by parts of the previous year's spring and late-summer generations. Each generation produced young after either 12 and 15 months or 12 and 19 months although each individual bred once only. Unlike other species of leeches studied N. obscura showed no direct correlation between cocoon production and water temperature, the primary prerequisite being a weight of more than 150 mg. Seasonal movements from the deep-water zone to the shore zone in spring and vice versa in the fall were recorded for the first time. The movements to the deep-water zone were not synchronous throughout the population, the spring generation completing its movements before the other components of the population.
Aplectana lynae n.sp. (Nematoda: Cosmocercidae) from the red-legged frog, Rana aurora aurora, in British Columbia
Authors: Kennedy Murray J.
Published: August 2008

Aplectana lynae n.sp., from the large intestine of Rana aurora, was collected from a small pond near Stave Falls, British Columbia, 35 mi (1 mi = 1.609 km) west of Vancouver. It is characterized by males with spicules 0.275–0.385 mm long and pointed, and a gubernaculum 0.110–0.132 mm long. Females are characterized by their size, 4.17–7.19 mm long, position of the nerve ring, 0.302 mm from the anterior end, and the location of the anus, which is 0.301 mm from the tip of the tail. This is the 5th species of Aplectana recovered from amphibians in Canada and the United States, and the 27th known to date.
Importance of algae in the diet of subarctic populations of Gammarus lacustris and Pontoporeia affinis
Authors: Moore James W.
Published: August 2008

Algae represented up to 13.5% by volume of the gut contents of Gammarus lacustris collected between June 1975 and May 1976 from a subarctic stream. While most species were consumed in proportion to their abundance in the environment, there was considerable selection against adnate and filamentous forms. The chloroplasts of most algae were readily broken down in the gut and the maximum length of ingested cell was 120 μm. All animals fed continuously during the summer but most ceased feeding in winter. Algae represented only 0.1–1.5% of the gut contents of Pontoporeia affinis collected from three subarctic lakes. Most algae were ingested, except for colonial Cyanophyta and algae attached to sand grains. As with G. lacustris, few cells contained intact chloroplasts. The maximum length of ingested organism was 100 μm. Feeding occurred continuously throughout the summer and appeared to cease between October and March.
Geographical distribution, hosts, and biology of Schistosomatium douthitti (Cort, 1914) Price, 1931
Authors: Malek Emile A.
Published: August 2008

The geographical distribution of Schistosomatium douthitti seems to coincide with the distribution of its snail hosts Lymnaea stagnalis and its varieties and Stagnicola palustris and its varieties. Another lymnaeid snail, Pseudosuccinea columella, is demonstrated to be a new susceptible host, and the nutria (Myocaster coypus) is found to be a good host and may be important in the dissemination if it migrates into new areas where the parasite does not occur at present. New information, relevant to transmission, is given on the biology of the unhatched and hatched miracidium, the development of the intramolluscan stages, the cercaria and its penetration of, and development in, the mammalian host.
Effect of temperature on healthy and microsporidia-infected continuous cultures of Malacosoma disstria hemocytes
Authors: Wilson G. G. , Sohi S. S.
Published: August 2008

The effects of constant temperatures on healthy and Nosema disstriae infected continuous cultures of Malacosoma disstria hemocytes were studied. Healthy cells grew best at 28 °C, followed closely by those at 25 and 30 °C. They grew very slowly at 20 °C. Cell growth was good at 35 °C for the first 4 days. If the medium was changed frequently cells could be kept at this temperature for a longer period without any adverse effect on their viability and growth. There were no significant differences in percentage infection and Nosema per cell in the infected cultures kept at 20, 25, 28, and 30 °C. However percentage infection and Nosema per cell were greatly reduced after 1 week at 35 °C, and eventually the microsporidia disappeared from the cultures kept at this temperature for 28 days. These observations support other reports to the effect that entomopathogenic microsporidia are unlikely to grow in warm-blooded vertebrates because of their high body temperature.
Leucocytozoon (Haemosporida; Leucocytozoidae) of the Falconiformes
Authors: Greiner Ellis C. , Kocan A. Alan
Published: August 2008

Falconiform-inhabiting species of Leucocytozoon are reviewed and a checklist of Falconiformes known to harbor Leucocytozoon is included. Morphological measurements were made from 11 falconiform species to examine the interspecific and intraspecific variations. These formed the basis for the redescription of gametocytes of L. toddi Sambon. It was proposed to synonymize L. audieri, L. bacelari, L. beaurepairei, L. circaeti, L. franchini, L. martyi, and L. mathisi with L. toddi.
Amphibious visual optics of the eyes of the double-crested cormorant (Phalacrocorax auritus) and the brown pelican (Pelecanus occidentalis)
Authors: Sivak J. G. , Lincer J. L. , Bobier W.
Published: August 2008

The visual optics of the eyes of the brown pelican and the double-crested cormorant were studied with the aim of determining their suitability for vision in air and in water. Refractive state (in air and in water), chromatic aberation, and corneal radii of curvature were measured. Both species are approximately emmetropic in air. However, while the pelican cannot compensate for the refractive loss of the cornea in water the cormorant can. Chromatic aberration is insignificant in both species and can have little effect in reducing the hyperopia associated with movement to water. The corneas of neither species were excessively flattened. We believe that the cormorant compensates for the refractive change induced by movement from air to water by means of a very large accommodative ability.
Circannual cycles of blood plasma freezing point and Na+ and Cl− concentrations in Newfoundland winter flounder (Pseudopleuronectes americanus): correlation with water temperature and photoperiod
Authors: Fletcher G. L.
Published: August 2008

A 4-year field program was conducted on the winter flounder to correlate changes in plasma Na+, Cl−, and freezing-point depression with sea-floor water and sediment temperatures, day length, salinity, depth of capture, and observations on burrowing in sediments.Plasma Na+, Cl−, and freezing-point depression showed annual cycles with maxima in winter (January–April) (temperature −1.1 to −1.4 °C) and minima in summer (July–October) (10–14 °C). The change in freezing-point depression from summer to winter was about 0.65 °C, 20% of this was attributable to Na+ and Cl− and the remaining 80% to the presence of an 'antifreeze.' The data suggest that plasma 'antifreeze' appeared in November (4–6 °C) and disappeared during May (−1.0 to 3 °C). During the winter the flounder were found only in the deeper areas of the sampling site and were usually buried up to 12–15 cm in the sediments which were warmer (0.1 to 0.4 °C) than the seawater.The plasma Na+, Cl−, and freezing-point depression of winter flounder held in the laboratory for 7 days were always significantly lower than the field-sampled fish. The differences between these two groups was greatest during the summer, suggesting that the effects of 'stress' during capture differ seasonaly.
Factors influencing local distribution and species diversity of forest small mammals in New England
Authors: Miller Donald H. , Getz Lowell L.
Published: August 2008

Napeozapus insignis and Blarina brevicauda were more abundant in sites with greater vegetation cover, especially herbaceous vegetation; Peromyscus leucopus and P. maniculatus were more abundant in sites with lesser herbaceous cover. Napeozapus insignis and Clethrionomys gapperi were more abundant in moist sites; B. brevicauda was only slightly more abundant in moist situations. Differences in water availability in their food appeared to be the primary reason for differences in local distributional patterns of the latter two species, both of which have high water requirements. The food of B. brevicauda (invertebrates) has a high water content even in dry sites, while water content of the food of C. gapperi (seeds, plant material, and fungi) reflects more directly soil moisture conditions. Napeozapus insignis, Microtus pinetorum, and Sorex cinereus had the narrowest habitat breadths; habitat breadths of P. leucopus, P. maniculatus, C. gapperi, and B. brevicauda were widest. Only the total number of species of trees and shrubs in a site displayed a correlation (positive) with species diversity of small mammals. Diversity of available food is presumed to be the proximate factor influencing diversity of forest small mammals in New England.
Development of muscle attachments in the crayfish opener muscle
Authors: Jahromi S. S. , Atwood H. L.
Published: August 2008

Development of attachments of muscle fibers to the muscle's central tendon and to the outer shell were observed in the opener muscle of the first walking leg of the crayfish Procambarus clarkii. Specimens obtained from eggs before hatching and at 1 day, 1 week, and 1 month after hatching were examined. Just before hatching, the central tendon is undeveloped. The tendinous cells contain few microtubules, and the cuticuloepidermal and myoepidermal junctions are not well differentiated. Soon after hatching, these junctions become more highly convoluted and the tendinous cells contain more microtubules. The elaboration of the muscle attachments coincides with the appearance of functional innervation in the muscle.
A new water mite genus from western Canada (Acari: Parasitengona: Anisitsiellidae)
Authors: Barr David
Published: August 2008

A new genus and species of the Anisitsiellidae, collected from a seepage area in central British Columbia, is described. The genus is noteworthy because, like Bandakia, it has a complete, unsculptured dorsal shield and the fourth tarsi bear well-developed terminal claws, although the appearance of a gland opening in coxa I is unique. The possession of a simple palp in this mamersopsoid genus further serves to justify the inclusion of the genera formerly belonging to the family Mamersopsidae within the family Anisitsiellidae.
Phenetic analysis of the stomatogastric musculature of several decapod Crustacea
Authors: Meiss Dennis E. , Norman Richard S.
Published: August 2008

If the evolution of the decapod Crustacea is, to a large extent, the evolution of their feeding methods, then evolutionary relationships should be reflected in the skeletal, muscular, and neural organization of the stomatogastric system. Homologies of the stomach muscles of several species of decapod Crustacea were identified by ossicle attachment sites. All species within a single infraorder were highly similar in muscle organization to each other but clear differences between infraorders were noted. A phenetic analysis yields a phenogram which reproduces the taxonomic scheme of earlier zoologists, based on independent external morphological characters. Identification of muscle relationships in this way is an essential step towards the comparative study of small motor systems producing stereotyped behaviors.
Food, feeding habits, and growth of goldeye, Hiodon alosoides (Rafinesque), in waters of the Peace–Athabasca Delta
Authors: Donald D. B. , Kooyman A. H.
Published: August 2008

The feeding habits of goldeye were determined by examining the food items found in 1785 stomachs collected from the Peace–Athabasca Delta, Alberta, in 1971, 1972, and 1973. Larval goldeye fed primarily on Calanoida and Cladocera. Post-larval goldeye fed mainly on Cladocera, Corixidae, and aerial insects but few Calanoida. These young fish selected the larger Cladocera and Calanoida from the plankton community. Growth was continuous from June to early September. Yearling and older goldeye had similar feeding habits with Corixidae being the most frequent food item present. They also fed on other aquatic and terrestrial invertebrates and small vertebrates. The food consumed on a given day reflected local as well as seasonal and yearly differences in abundance of the various organisms. Stomachs of these goldeye contained the least amounts of food during July and August. Yearling and fish at least up to age III showed appreciable growth only during June and July.
Locomotor hyperactivity induced in the bluegill sunfish, Lepomis macrochirus, by sublethal concentrations of DDT
Authors: Ellgaard Erik G. , Ochsner J. Coller , Cox J. Keith
Published: August 2008

A quantitative description of the effects of sublethal concentrations of DDT on the locomotor activity of the bluegill sunfish, Lepomis macrochirus, is presented. DDT-elicited hyperactive locomotor responses at all the concentrations examined (0.008, 0.01, 0.02, 0.04, 0.06, 0.08, 0.1, and 0.2 parts per billion (ppb)) and the degree of such responses were concentration dependent. Maximal effects at each concentration were observed within 8 days after addition of DDT to the environment. At their maxima, fish at 0.008 ppb were 1.3 times as active as control fish, whereas fish at 0.2 ppb were 3.0 times as active as controls. The effects of DDT on locomotor activity were not reversed even after the fish were transferred back into tap water for 2 weeks.
On the size determination of bumble bee castes (Hymenoptera: Apidae)
Authors: Plowright R. C. , Jay S. C.
Published: August 2008

Female larvae of Bombus rufocinctus Cresson, a 'pollen-storing' species showing well-marked intercaste size dimorphism, were hand reared on a diet of pollen, honey, and water from the penultimate larval instar until adulthood. Bees of any desired size, between upper and lower limits, were obtained simply by starving larvae at appropriate points during the last instar. Larvae were able to produce silk soon after ecdysis into the last instar, but fully developed capacity to spin was not attained until about 165 mg. After this point, the rate of spinning was found to depend inversely upon the frequency with which larvae were fed. Growth during the last instar, under a variety of periodic ad libitum feeding regimes, was approximately logistic. These results suggest a simple biophysical explanation to account for the determination of caste-specific body size in Bombus; adult size is the outcome of differential rates of growth and silk production which are, in turn, dependent upon the ambient rate at which larvae are fed by the adult workers. Given appropriate parameter values, this model can satisfactorily explain the suppression of individuals of intermediate size. Preliminary experiments to test the hypothesis are described, and its evolutionary implications are discussed.
Variation in the social calls of little brown bats (Myotis lucifugus)
Authors: Fenton M. B.
Published: August 2008

The social calls of 14 Myotis lucifugus (5 adult males; 5 adult females; 2 subadult males; 2 subadult females) produced under controlled conditions were more variable than echolocation calls made by hunting individuals in the wild. The social calls contained lower frequencies and in some cases were of longer duration than the echolocation calls. Careful examination of sound spectrographs of the calls indicated tremendous variability in details of frequency and time. Although several types of calls can be recognized, a discrete classification is not feasible because of the variability. The possible significance of the variation in the calls of these bats is discussed in the context of recognition of individuals by their vocalizations.
Comments concerning postcloacal bones in geckos (Reptilia: Gekkonidae)
Authors: Russell Anthony P.
Published: August 2008

Postcloacal sacs and bones are restricted to three extant families of lizards, the Gekkonidae, Pygopodidae, and Xantusiidae, and function during copulation. The distribution of postcloacal bones in the subfamily Gekkoninae is variable and some genera apparently show loss of these elements. Not all previous reports of loss are accurate. This note indicates some discrepancies and includes statements which enhance previous functional interpretations of these structures.
The hypobranchial gland in the Bivalvia
Authors: Morton Brian
Published: August 2008

The hypobranchial gland of the protobranchs Nucula nucleus and Solemya parkinsoni comprises mucous cells flanked by inversely conical and ciliated regenerative cells. A similar structure occurs in the filibranch Monia squama and in the eulamellibranchs Fimbria fimbriata and Corbicula fluminea except that in the two latter the conical cells are not ciliated and in C. fluminea they are also secretory.The primitive function of the hypobranchial gland was the consolidation, in a mucous stream, of waste material for expulsion via the exhalant aperture. The evolution of the filibranch and eulamellibranch ctenidia dividing the mantle cavity into infrabranchial and suprabranchial chambers with waste material removed via the inhalant aperture abrogated the need for such a structure. It has, however, been retained in some filibranchs where the ctenidia are possibly less efficient.In Nucula delphinodonta the hypobranchial gland secretes a brood pouch attached to the shell, Enhancement of this function in lamellibranch bivalves, notably C. fluminea and possibly F. fimbriata, has resulted in the gland functioning as an organ for the nutrition of developing larvae incubated in the suprabranchial chamber. An epithelium with regenerative cells of different structure occurs in the similarly incubatory Sphaerium corneum.
The vascularization and the neuroendocrine pathways of the pituitary gland in the Atlantic salmon, Salmo salar
Authors: Fridberg G. , Ekengren B.
Published: August 2008

The pituitary gland of the Atlantic salmon, Salmo salar, is supplied by two arterial systems. The hypophysial arteries irrigate the rostral neurohypophysis and the pars distalis. The caudal hypothalamic arteries enter the neurointermediate lobe. In contrast with the capillary plexa in the neurohypophysis, the dorsal arteriol loops lack neurocrine terminals. An elaborate system of branches of the perivascular spaces extends into the neurohypophysis and it is continuous with the basement membrane in the neuroadenointerface and the intercellular channels of the pars distalis. This system is assumed to be an efficient conveyor of neurocrine factors and hypophysial hormones and an important vascular component. In the salmon the brain mediates its information to the pituitary through neurovascular links and the cells of the adenohypophysis are not innervated.The rostral neurohypophysis fulfills all criteria of being a median eminence although it lacks a well-defined portal system and it represents a secondary development from an original type seen in gnathostome vertebrates. It is suggested that the direct innervation of the endocrine cells in the pars distalis is a specialization and appeared late in the evolution of the teleost pituitary.
Biological models of two acarine predators of the grain mite, Acarus siro L.
Authors: Burnett T.
Published: August 2008

A biological model of predation was developed using granular food held in closely packed screen trays to propagate the grain mite, Acarus Siro L., and two of its predators, Blattisocius dentriticus (Berl.) and Cheyletus eruditus (Schrank). Both predators limited prey abundance. Cannibalism among predators, particularly C. eruditus, was an important factor in ensuring the survival of the prey and predator populations. Cheyletus eruditus eliminated B. dentriticus when the two species were propagated in the same experimental universe. Cyclicity and dispersion of the interacting species appeared to result more from the initial age structure and from dispersion of the prey than from predator attack. A population model was used to assess the relative importance of the population components of A. siro and C. eruditus in the simplified predator–prey interactions.
Notes on mermithid parasitism of Newfoundland blackflies, with the first record of Neomesomermis flumenalis from adult hosts
Authors: Mokry Joseph E. , Finney Jean R.
Published: August 2008

Field-collected pupae of Simulium venustum and Prosimulium mixtum were allowed to eclose in the laboratory and the adults were dissected to reveal the presence or absence of mermithid parasites. Twenty-six (11.7%) of 221 female P. mixtum were found parasitized; all 187 males examined were unparasitized. Nematodes emerged from 10 (14.3%) of 70 female P. mixtum when placed in water-filled dishes. The nematodes recovered from P. mixtum were Neomesomermis flumenalis (66.6%), Isomermis sp. (26.7%), and Gastromermis viridis (6.7%). Forty-three (22.2%) of 194 female S. venustum were parasitized; all 134 males examined were unparasitized. Three (5%) of 60 male pupae of S. venustum were parasitized; 7 (8%) of 86 females were found to harbour mermithids. The nematodes recovered from S. venustum were Hydromermis sp. (75%), G. viridis (12.5%), and N. flumenalis (12.5%).
Lower lethal levels of pH for embryos and alevins of Atlantic salmon, Salmo salar L.
Authors: Daye P. G. , Garside E. T.
Published: August 2008

Embryos and alevins of Atlantic salmon, Salmo salar L., at various stages of development were subjected to several levels of low pH ranging from 4.3 to 2.7, for maximum exposures of 10 000 min in static bioassays at 5 or 6 °C, after incubation from fertilization at pH 6.9–6.6 and 5.0–6.7 °C. Sensitivity of the embryos and alevins to pH stress was dependent on the stage of development. Embryos in early cleavage were more sensitive to low pH than older encapsulated embryos. Alevins were more sensitive to low pH than embryos. The lower lethal limit for embryos during early cleavage was about pH 3.6, while for older embryos in two sequential stages just before hatch it was about pH 3.0 and pH 3.1, successively. Alevins subjected to low pH levels at 7 days and at 28 days after median hatch had a lower lethal limit of about pH 4.0.
A histological study of early chondrification in Malathion-treated chick embryos, with emphasis on cell numbers, cell size, and patterns of matrix deposition
Authors: Jackson S. B. , Gibson M. A.
Published: August 2008

Chick embryos were given a teratogenic dose of Malathion at the 5-day incubation stage and its effects on the early histogenesis of the tibiotarsus were studied during the 8- to 20-day incubation period. This investigation included studies of the growth rate as indicated by mitotic index and the number of cells per unit area, of cell activity as indicated by cell size and the amount of matrix per cell, and of matrix formation as indicated by rates of deposition and erosion and by histochemical staining. The Malathion caused an increased proliferation of the chondroblasts during the initial chondrification stages only. It led to an increase in the number and size of the chondrocytes, particularly in areas of reduced matrix deposition. The Malathion primarily influenced the deposition of the ground substance, causing: (1) a reduction in the amount of ground substance deposited, (2) a reduction in the degree of sulfation and polymerization of that ground substance which was deposited, and (3) a lysosomal-mediated resorption of the formed matrix along the epiphyseal–diaphyseal border. In these ways, the Malathion causes a reduction in the growth rate of the tibiotarsus and a weakening of the cartilage model which subsequently results in a bending of the tibiotarsus.
The effects of photoperiod and temperature on the induction and termination of reproductive resting stage in the freshwater amphipod Hyalella azteca (Saussure)
Authors: March B. G. E. de
Published: August 2008

Three experiments, one on the induction of reproductive resting stage and two on its termination, were performed to determine the effects of various combinations of temperature and photoperiod on the induction and termination of reproduction in Hyallella azteca. These showed that only photoperiod determined whether reproduction was continued or discontinued but that temperature influenced the rate of all changes. The 12 L – 12 D photoperiod terminated reproduction for at least 4 months at temperatures between 12 and 25 °C in animals previously reproducing at a 16 L – 8 D photoperiod. The 12 L – 12 D photoperiod also induced reproduction at temperatures between 16 and 26 °C in animals previously held in a reproductive resting stage in dim light. In contrast, the 16 L – 8 D photoperiod induced and maintained reproduction consistently, and the 8 L – 16 D photoperiod halted reproduction and maintained a reproductive resting stage consistently. The induction of reproduction occurred faster at higher temperatures.It is believed that although photoperiod is the main cue in the induction and termination of reproduction, active reproduction takes place when environmental temperatures are 20 to 26 °C, since optimum reproduction and growth rates occur in this range. The adaptive advantage and the biogeographic variability of the photoperiodic response are discussed.
Uptake, distribution, and turnover of catecholamine radiolabel in the goldfish, Carassius auratus L.
Authors: Busacker Greg P. , Chavin Walter
Published: August 2008

As the uptake, distribution, and turnover of epinephrine and norepinephrine are largely unknown in teleosts, the relative tissue affinities for these circulating catecholamines were evaluated in the goldfish, Carassius auratus L. Since sufficient circulating levels of catecholamines available for uptake by tissues in vivo are a transient event occurring after stress, it was decided to investigate the uptake and decline of radiolabeled catecholamines over a short period of time, noting that uptake would coincide with high endogenous levels from handling stress while decline would be unaffected by stress. Fish injected with l-[3H]norepinephrine and dl-[carbinol-14C]epinephrine were killed from 0.5 to 1024 min postinjection, and the catecholamine radiolabels determined in 19 tissues. Six different uptake and retention patterns for individual tissues were present, but all tissues examined showed preference for the norepinephrine radiolabel. Among the excretory mechanisms in the goldfish, the liver is prominent in catecholamine elimination via the bile. A blood–brain barrier appears present for epinephrine, but not for norepinephrine; epinephrine is excluded from the hypothalamus and pituitary. Further, adipose tissue takes up only norepinephrine. In some teleostean tissues, therefore, the two catecholamines are handled differently than in the comparable mammalian tissues.
Cone synaptic ribbons and retinomotor changes in the brook trout, Salvelinus fontinalis (Salmonidae, Teleostei), under various experimental conditions
Authors: Wagner H.-J. , Ali M. A.
Published: August 2008

Cone synaptic ribbons in the brook trout were studied and compared with retinomotor responses during a normal 24-h cycle and during 72 h of constant light or darkness. There is a reduction of synaptic ribbons to 65% of the daytime value during a normal night. In the absence of light stimuli, retinomotor movements cease after 20–30 h, whereas rhythmic oscillations of synaptic ribbons, although dampened, persist until the 3rd day. It appears that in the brook trout, which is an arhythmic fish, there is no endogenous control of retinomotor responses and only very little control of synaptic ribbons. The significance of synaptic ribbons for synaptic transmission and of their involvement in endogenous circadian rhythms is discussed.
Energy requirements during reproduction of Peromyscus maniculatus
Authors: Stebbins Lucius L.
Published: August 2008

Weight-specific food consumption, gross daily energy consumption, and weights of breeding groups, lactating females, and young litters were monitored between time of mating and 2 weeks after weaning. No observable changes in weight-specific or gross daily energy consumption was evident in the 3 weeks before the week in which birth occurred, although weights of females had by then increased an average of 36%. Gross daily energy consumption increased by 96%, 136%, and 194%, respectively, during the 1st, 2nd, and 3rd weeks after birth. Weights of females dropped significantly in the week before weaning.
Circulation during intermittent lung ventilation in the garter snake Thamnophis
Authors: Burggren Warren
Published: August 2008

Systemic and pulmonary arterial and ventricular blood pressures have been recorded in both lightly anaesthetized and unanaesthetized, unrestrained garter snakes of the genus Thamnophis. Systemic blood pressure was 65/44 cmH2O compared with only 52/21 cmH2O in the pulmonary circulation. Peak systolic pressures throughout the ventricle were identical and were the same as systemic systolic pressures. Reduction of pulmonary arterial blood pressure arose solely from an impedance to blood flow located in a narrow region of the pulmonary ventricular outflow tract. Atropine greatly reduced this impedance. No changes in the blood pressure relationships within the central arterial circulation were observed during intermittent, voluntary lung ventilation. It is concluded that the ventricle of the snake Thamnophis functions as a single pump which perfuses both the pulmonary and systemic circulations, with pulmonary and systemic arterial pressure differences arising from the impedance characteristics of the ventricular outflow tracts.
Physiology of nutrient uptake by the entomophilic nematode Mermis nigrescens (Mermithidae)
Authors: Rutherford T. A. , Webster J. M. , Barlow J. S.
Published: August 2008

The physiology of glucose and amino acid uptake by the parasitic larval stages of the entomophilic nematode Mermis nigrescens was investigated in vitro using radioisotope-labelled substrates. Both glucose and amino acid uptake are transcuticular processes that are saturable with increasing substrate concentration but are not coupled to co-transport of sodium ions and are not energy requiring. Amino acid transport is a stereospecific membrane transport system probably located in the cuticle of the nematode. The sites for glucose transport, however, are believed to be beneath the cuticle as glucose transport is only saturable in the thin-cuticled 14-day-old larvae whereas it is not in the thick-cuticled 21-day-old larvae. Glucose transported by M. nigrescens is not converted to trehalose, a common pathway in other invertebrates, nor is trehalose found within the nematode's tissues or body fluids.
Strategies for coexistence in three species of net-spinning caddisflies (Trichoptera) in second-order southern Appalachian streams
Authors: Malas Diane , Wallace J. Bruce
Published: August 2008

Three species of net-spinning caddisflies, Parapsyche cardis, Diplectrona modesta, and Dolophilodes distinctus were studied. Larvae of Dolophilodes are found at the lowest current velocities followed by Diplectrona, then Parapsyche, which prefer the higher velocities. Parapsyche larvae are most abundant on upper surfaces of stones while Diplectrona and Dolophilodes are found primarily on undersides of stones. These distribution patterns are probably related to capture net mesh dimensions which differ greatly for the three species, Parapsyche having the largest and Dolophilodes the smallest meshes. Significant correlations existed for mean foregut particle size and capture net mesh opening size between instars of all species within seasons, between instars of all species throughout the year, and between instars within species throughout the year. These correlations support the contention that particle size selection is an important aspect of feeding differences between species. There are large differences between mesh opening sizes of last-instar Dolophilodes and first- and second-instar Diplectrona larvae. However, based on mean particle size measurements of foregut contents, there is no corresponding gap in the spectrum of particle sizes used for food. Dietary composition also varied between species. Parapsyche consumed primarily animal material. Fine particulate detritus composed over 95% of Dolophilodes gut contents and Diplectrona consumed mostly vascular plant and detritus fragments in late instars and fine particulate detritus in early instars.
Role of enzymes in the mechanism of shell penetration by the muricid gastropod, Thais lapillus (L.)
Authors: Webb Roy S. , Saleuddin A. S. M.
Published: August 2008

The role of the boring organ in the mechanism of shell penetration by Thais lapillus (L.), a muricid gastropod, has been investigated by cytochemistry and biochemistry. Sites of acid phosphatase and carbonic anhydrase activity were localized and the biochemical activities of these enzymes were measured in the boring organ of both nonboring and actively boring animals. The lysosomal marker enzyme, acid phosphatase, was investigated to assess the role of lysosomes in the boring mechanism. Acid phosphatase activity was localized on the microvillar membranes of the epithelial cells of the boring organ. There was no significant difference in the biochemical activity of acid phosphatase between actively boring and nonboring specimens. Carbonic anhydrase was localized prominently in the epithelium of the boring organ. The microvilli showed no localization but all other regions of the epithelium were dominated by reaction product. The boring organ demonstrated high levels of carbonic anhydrase activity but no significant difference could be detected between actively boring and nonboring specimens. The possible involvement of these enzymes and their role in the mechanism of shell penetration by muricid gastropods has been discussed.
Role of the thyroid gland in ovarian maturation of the goldfish, Carassius auratus L.
Authors: Hurlburt Mary E.
Published: August 2008

Thyroxine (T4) stimulated ovarian development in immature intact goldfish after both 8 and 17 weeks of treatment. T4 alone had no influence on ovarian development in hypophysectomized regressed adult individuals, but did augment the ovarian response to salmon gonadotropin (SG-G100) after pituitary ablation. Pituitary gonadotropin cell and nuclear diameters in maturing fish were decreased after T4 treatment, while immersion of immature fish in the goiterogen, 6n-propy1-2-thiourucil, resulted in a slight increase in these values. Hepatosomatic index values were higher in T4-treated hypophysectomized fish than in controls.The findings indicate that thyroid hormones act synergistically with gonadotropin to influence ovarian development in goldfish and suggest that these effects are mediated, directly or indirectly, by a T4-induced increase in ovarian sensitivity to gonadotropic stimulation. Thyroid hormones appear to inhibit gonadotropin production in this species, although the physiological significance of this is uncertain.
Measurement of feeding threshold in the blowfly Phormia regina Meigen
Authors: Thomson A. J.
Published: August 2008

The waxed-stick mounting method for threshold determinations produces a high mortality rate in long-term experiments. A mounting process which allows the experimental flies to be returned to a holding cage after testing, eliminating this mortality effect, is described.Some traditional methods of threshold measurement incorporate a bias owing to adaptation effects. An experimental procedure, with an appropriate statistical test, is described to avoid such adaptation effects in the determination of threshold. Feeding threshold is high after ecdysis. The time taken for the threshold for a particular sugar to reach a basal level appears to be inversely proportional to the absolute stimulating power of the sugar. The high postecdysis threshold and its subsequent slow decline appear to be associated with the air swallowed as part of the ecdysis process. The basal thresholds recorded are in agreement with those indicated in the literature.
The influence of current velocity and substrate on the distribution and drift of two species of mayflies (Ephemeroptera)
Authors: Corkum Lynda D. , Pointing P. J. , Ciborowski Jan J. H.
Published: August 2008

The effects of substrate type and current velocity on the distribution and drift of Baetis vagans McDunnough and Paraleptophlebia mollis (Eaton) were examined in an artificial stream. Of those B. vagans (swimming nymphs) remaining on the substrates, most were retrieved from branches while few were found in inorganic substrates. In all cases, numbers of B. vagans remaining on the substrates increased as current velocities increased. Paraleptophlebia mollis (crawling nymphs) were most frequently associated with gravel (11.2–16 mm diameter), whereas branches were of less importance.At 50 cm/s and during darkness, the proportion of P. mollis drifting from a 'least preferred' substrate was comparable with that of B. vagans. At lower velocities or in light, B. vagans drifted more frequently than did P. mollis, regardless of substrate type. For both species, drift was a significant mechanism in dispersal of individuals from unfavourable areas.
Peniculus asinus (Copepoda: Pennellidae), a new species of copepod parasitic on fishes of the genus Sebastes along the west coast of North America
Authors: Kabata Z. , Wilkes S. N.
Published: August 2008

Peniculus asinus, a new species of copepod parasitic on Sebastes (Pisces: Teleostei) off the Pacific coast of Canada is described and illustrated. The copepod is an unique member of its genus in that it possesses cephalothoracic holdfast processes. The discovery of a Peniculus with these processes is taken as evidence confirming the place of this genus in the family Pennellidae.
Swimming by the water mite Limnochares americana Lundblad (Acari, Parasitengona, Limnocharidae)
Authors: Smith Bruce P. , Barr David
Published: August 2008

Locomotory patterns of Limnochares americana were analyzed from visual observations and cinema and still photography. In free swimming it uses only the last two pairs of legs such that the third leg on the left side and the fourth leg on the right side are in phase and the third leg on the right side and fourth leg on the left side are in phase. Legs on opposite sides and successive legs on the same side show a phase difference of 0.5 cycle (180°). Orientation appears to be cued primarily by direction of illumination and water movement. The swimming hairs form collapsible blades that improve the efficiency of each leg in swimming. Manoeuvering and control of roll, pitch, and yaw are accomplished primarily by altering the direction of the power stroke of various legs as the distal segments are rotated at the trochantofemoral joint.
Comparaison de méthodes de répression d'oiseaux s'attaquant au maïs fourrager
Authors: Potvin Normand , Bergeron Jean-Marie , Genest Jean
Published: August 2008

To reduce damage to corn fields by redwing blackbirds, grackles, cowbirds, and pigeons we tried four means of control: Avitrol 200, Methiocarb, acetylene canon, and Av-alarm. During sowing, all means of control were efficient to a certain extent. Damage was reduced by 28% with use of the acetylene canon and by 100% with the use of a combination of the canon and the Av-alarm. At the beginning of harvesting only Methiocarb was not effective. Other products reduced damage from 54 to 93%. Populations of redwing blackbirds and grackles comprised at least 3400 individuals by that time.
The estimation of natality in a fruit-infesting insect (Diptera: Tephritidae)
Authors: Pritchard Gordon
Published: August 2008

Extraction of eggs of Dacus tryoni from fruit was aided by first identifying oviposition sites with a water-soluble dye and then digesting the fruit tissue around the oviposition site with a mixture of enzymes consisting of equal parts of 1% pectinase and 1% cellulase. The numbers of eggs laid per week were estimated by a formula that incorporated the numbers of hatched and unhatched eggs present on one occasion each week, the proportion of fertile eggs in each variety of fruit, and the development time of eggs.Many more eggs were laid in an orchard in New South Wales, Australia, in a wet year (1966–1967) than in a dry year (1965–1966). This was due in part to a larger population of adults that migrated into the orchard in the wet year and to the fact that fruit remained on the trees longer. There was evidence that the rate of oviposition in the wet season fell off as fruit became scarcer towards the end of the season. Aggressive behaviour of females on fruit and movement of gravid females away from the orchard are possible explanations.
The effects of hypophysectomy on seasonal changes in plasma freezing-point depression, protein 'antifreeze,' and Na+ and Cl− concentrations of winter flounder (Pseudopleuronectes americanus)
Authors: Fletcher G. L. , Campbell C. M. , Hew C. L.
Published: August 2008

The annual changes in plasma Na+ and Cl− concentrations took place in the absence of the pituitary, although the magnitude of the change was significantly reduced. The annual increase in plasma freezing-point depression also occurred in the absence of the pituitary. However the decrease normally observed in the spring and early summer did not occur.Sham-operated winter flounder transferred from ambient seawater (−1 °C) and day length to warm water (6–12 °C) and 18-h day length showed a reduction in plasma Cl− concentration and freezing-point depression and a loss of the protein 'antifreeze.' Hypophysectomized flounder treated in the same way showed a reduction in plasma Cl−, but no decline in freezing-point depression and protein 'antifreeze.'These results suggest that an intact pituitary is necessary for the disappearance of the protein 'antifreeze' from the plasma of the winter flounder.
Seasonal variation in plasma LH, FSH, prolactin, and testosterone concentrations in adult male white-tailed deer
Authors: Mirarchi R. E. , Howland B. E. , Scanlon P. F. , Kirkpatrick R. L. , Sanford L. M.
Published: August 2008

Blood samples were collected monthly from captive and wild adult (12 months old or older) male white-tailed deer (Odocoileus virginianus) over 1 year in southwest Virginia. Plasma was assayed for luteinizing hormone (LH), follicle-stimulating hormone (FSH), prolactin (PRL), and testosterone (T) using radioimmunoassays. LH and T levels for the captive and wild deer were essentially similar and followed a distinct annual cycle. LH concentrations (nanograms per millilitre) peaked earlier (October, captive, 4.5 ± 1.8 (mean ± standard error); September, wild, 3.3 ± 0.9) than T concentrations (nanograms per millilitre) (November, captive, 13.3 ± 2.7; November, wild, 23.7 ± 7.8) and dropped off sharply prior to, or concomitant with, T concentrations. LH and T levels were lowest during the late winter and spring. T concentrations were closely correlated with androgen levels (Mirarchi, R. E., P. F. Scanlon, R. L. Kirkpatrick, and C. B. Schreck. J. Wildl. Manage. 41: 178–183 (1977)) determined by competitive protein binding assay. Mean PRL and FSH concentrations in wild and captive deer also displayed seasonal variations. Prolactin concentrations (nanograms per millilitre) were highest in May (147.5 ± 0.0) and lowest in November while FSH levels (nanograms per millilitre) peaked in September (180.2 ± 22.4) and were lowest in March. Differences in hormone concentrations between deer and sheep, and the relationship between PRL and antler growth and FSH and spermatozoan production, are discussed.
The immediate effects of deafferentation of the lungs on heart and breathing frequencies in ducks
Authors: Jones David R. , Bamford Owen S.
Published: August 2008

Three unilaterally vagotomised ducks were subjected to 'instantaneous' deafferentation of the remaining innervated lung by pulling snares through the vagal branches while recording heart and breathing frequencies. Deafferentation caused immediate cardiac and respiratory depression but the effect on tidal volume was inconsistent. Five minutes after deafferentation, breathing frequency had fallen from 25–30 to 6–8 breaths min−1. Arterial pH, [Formula: see text], and [Formula: see text] were 7.49, 12, and 4.07 kPa before deafferentation and 7.05, 9.7, and 6.8 kPa, respectively, 10 min after deafferentation. These results confirm the idea that some form of feedback from the lungs is essential for generation of stable respiratory rhythms in birds and further indicate that artificial ventilation is advisable, for some hours, after deafferentation.
Presence of DNA nuclear membrane complex in Tetrahymena pyriformis
Authors: Kreis Christopher G. , Stubbs John D.
Published: August 2008

A DNA-membrane complex enriched in newly synthesized DNA has been isolated from synchronized Tetrahymena pyriformis GL macronuclei. The complexes are formed in the presence of the detergent sodium lauroyl sarcosinate and most of the DNA and membrane of the macronuclei. Shearing of the complex is sufficient to release most of the bulk DNA. However, 90% of newly synthesized DNA remains tightly bound to the complex. It can be shown by pulse–chase experiments that this newly synthesized DNA can be chased from the complex, thus indicating that this DNA is only transiently associated with the complex. The complex appears to be cell cycle specific since it can only be isolated from cells in the S period. Chromatin or purified DNA from log or stationary phase cells does not form a complex when mixed with the detergent and disrupted macronuclei. It appears from these data that the DNA growing points may initiate at the membrane–DNA junction.