bluuebunny/crossref_metadata_2025 huggingface dataset:
Self- and allo-grooming behavior in some ground squirrels (Sciuridae), a descriptive study
Authors: Steiner A. L.
Published: January 2008

The different grooming behavior patterns, postures, and body cleaning motions, analyzed by cinephoto techniques, are first described in three species of ground squirrels, studied in captivity and in the field. Most patterns recorded appear to be widespread among mammals. Some of them, however, appear to be more specialized, reflecting apparently the propensity of some rodents, particularly sciurids, to assume a bipedal, sitting-up posture, and to use the forepaws in "manipulating" tasks. Some "cleaning" motions, particularly face washing and rubbing of some body parts with the limbs, might also represent scent-related behavior. Areas that are known to bear secretory apocrine glands, around the mouth corners for instance, are consistently rubbed. Other body areas, particularly the head region (cheeks, supra- and infra-orbital, occipital, and ear areas), one ventrolateral and anterodorsal area and possibly the root of the tail, dorsally, show darker zones, of oily appearance, that might also be involved in scent-related behavior, during grooming. Allogrooming, also, is often directed onto the above-mentioned areas, particularly the ones on the head. Allogrooming can also be affected by dominance/subordination and (or) agonistic relationships.
Observations on the anatomy of the respiratory system of the river otter, sea otter, and harp seal. I. The topography, weight, and measurements of the lungs
Authors: Tarasoff F. J. , Kooyman G. L.
Published: January 2008

The lungs of the river otter and sea otter are triangular in outline, with the apex directed cranially. Lungs of the harp seal are oval in outline. The lung shapes correspond closely to the shape of the thoracic cage of each species. The hilus is located more cranially in the harp seal than in the river otter and sea otter. The ratio of total lung weight/100 g body weight is 1.39 in the river otter, 3.86 in the sea otter, and 1.31 in the harp seal. In the river otter and sea otter the right lung has four lobes (compared with two in the left) and is always the larger and heavier. In the harp seal each lung has three lobes and are topographically more similar to each other, with the left lung being the larger and heavier.
Observations on the anatomy of the respiratory system of the river otter, sea otter, and harp seal. II. The trachea and bronchial tree
Authors: Tarasoff F. J. , Kooyman G. L.
Published: January 2008

The trachea of the river otter and sea otter are morphologically similar to each other, whereas the trachea of the harp seal is relatively shorter and broader and has noncalcified overlapping cartilaginous rings and a relatively thicker lamina propria. The harp seal has fewer cartilaginous rings, the arms of which overlap dorsally in the cranial two-thirds of the trachea. The bronchial blanching patterns are similar in the river otter and sea otter, with the pennate-like branching of the lobar bronchi corresponding to the lobes of the lungs. In the harp seal there are more dichotomous branchings of the lobar bronchi, with close symmetry between the right and left lungs. Bronchiograms and dissections indicate that the numbers of subsegmental bronchioles increase from the river otter to sea otter to harp seal.
The ultrastructure of the cuticle of the nematode Syphacia obvelata (Rudolphi, 1802). II. Modifications of the cuticle in the head end
Authors: Dick T. A. , Wright K. A.
Published: January 2008

The head region of the pinworm Syphacia obvelata (Rudolphi, 1802) has been examined to determine the nature of modification of the cuticle responsible for, or associated with, lips and buccal capsule, cephalic papillae and amphids, cephalic inflations, and cervical alae. The median zone of the cuticle was found to be the most modified and variation in the extent and distribution of striated material is compatible with its proposed structural role. The variations found are probably related to compensation for stresses that may develop in the cuticle during the complex movements of the head end. Lips are only inconspicuous expansions of the body wall cuticle, while esophageal cuticle is strikingly different in appearance. It is proposed to refer to all regions of the mouth cavity bounded by both the lips and esophagus as the buccal capsule while only the limited region bounded by body wall cuticle may be referred to as stoma. A mechanism involving three groups of intrahypodermal cytoskeletal filaments attached to the tips of somatic muscles, esophagus, and cuticle is proposed to move the lips.
An electrophoretic comparison of histones in anuran testes
Authors: Bols N. C. , Kasinsky H. E.
Published: January 2008

An electrophoretic comparison of basic proteins present in Rana, Xenopus, and Bufo testes reveals a broad spectrum of histones in these anurans. Rana testis contains only the somatic complement of histones. However, Xenopus testis shows three bands migrating more rapidly than histone IV, the fastest moving histone in the somatic region. These three bands are specific to Xenopus testis. One band migrating even more rapidly in the protamine region is a specific component of Bufo testis. On the basis of previous cytochemical data, it would appear that these testis-specific histones in Xenopus and Bufo are likely to be confined to the sperm nucleus.
Activity of autotransplanted pituitary glands in goldfish, Carassius auratus L., maintained in different ambient salinities
Authors: Leatherland J. F. , Ensor D. M.
Published: January 2008

Pituitary histology was compared in in situ and autotransplanted glands in goldfish which were acclimated to four different ambient media. In addition, the histology of the gonad and interrenal and thyroid gland and plasma Na+ and K+ concentrations were examined in these fish as well as in hypophysectomized animals acclimated to the same external media.The rostral pars distalis (RPD) epsilon cells, presumptive proximal pars distalis (PPD) thyrotrophs, and pars intermedia (PI) PAS stainable (+ve) cells appear to function only with intact hypothalamic–adenohypophysial connections whereas the remaining pituitary cell types were independent of hypothalamic control and in some cases (RPD eta cells and basophil cells) were directly affected by environmental salinity.The thyroid epithelial cell height (TEH) was elevated in all the groups of fish in 30% seawater. The significant (albeit small) rise in pharyngeal TEH in hypophysectomized animals in 30% seawater may indicate a direct effect of the ambient environment on thyroid gland activity.The interrenal cell nucleus diameter was not significantly affected by any of the treatments although cytological changes were found in the interrenal cells in hypophysectomized and to a lesser extent in autotransplanted fish, which indicated a lower activity in these groups when compared with shamoperated controls; there was no apparent effect of salinity on interrenal cell activity.Plasma Na+ concentrations were not maintained in fish with autotransplanted pituitaries acclimated to hypotonic media (distilled and tap water); thus the viability of endocrine factors which regulate plasma Na+ levels in the goldfish appears to be impaired in these fish.
Nematodes of the family Mononchidae (Dorylaimida: Mononchoidea) from Sable Island, Canada
Authors: Mulvey R. H.
Published: January 2008

Eight species in the predaceous family Mononchidae are reported from Sable Island, Canada, for the first time. Measurements and illustration of these species are provided.
Corallobothrium parafimbriatum sp. n. and Corallotaenia minutia (Fritts, 1959) comb. n. (Cestoda: Proteocephaloidea) from Algonquin Park, Ontario
Authors: Befus A. D. , Freeman R. S.
Published: January 2008

Corallobothrium parafimbriatum sp. n. and Corallotaenia minutia (Fritts, 1959) comb. n. are reported from the brown bullhead, Ictalurus nebuhsus, in Algonquin Park, Ontario; Corallobothrium fimbriatum, although reported previously, was not found. C. parafimbriatum is smaller, has fewer segments, testes, and uterine branches, and has a different egg than C. fimbriatum; secondary protonephridial pores are present on the former, but absent on the latter species. C. parafimbriatum is the same size as Corallotaenia minutia but differences in the vitelline columns, ovary, and eggs clearly distinguish the two. The genus Corallotaenia is amended. Since the paratype of Corallobothrium intermedium Fritts, 1959 has sphincters on two suckers, it is reassigned as Megathylacoides intermedium (Fritts, 1959) comb. n.
Life cycles of two corallobothriin cestodes (Proteocephaloidea) from Algonquin Park, Ontario
Authors: Befus A. D. , Freeman R. S.
Published: January 2008

Corallobothrium parafimbriatum and Corallotaenia minutia infected bullheads in all lakes sampled but Billy Lake, where only C. parafimbriatum occurred. Plerocercoids and maturing worms are in the gut of bullheads throughout the year although gravid adults occur only during the summer in potentially reproductive bullheads. Fully differentiated plerocercoids of C. parafimbriatum grew in Cyclops bicuspidatus, C. vernalis, Tropocyclops prasinus, and an immature cyclopoid; C. minutia developed in C. vernalis, C. parafimbriatum required 21 days at 18C for growth, differentiation, and invagination or retraction of the scolex, and C. minutia required 39 days at 18C. After initial development in a copepod, plerocercoid I of C. minutia requires parenteral development in a fish, whereas plerocercoid I of C. parafimbriatum does not. Parenteral plerocercoids of C. minutia, Proteocephalus ambloplitis, and dead metacestodes were common in bullheads. As with other proteocephalids, corallobothriin plerocercoid I develops to plerocercoid II in fish. Plerocercoid I from copepods may enter the viscera, but unlike P. ambloplitis and Ophiotaenia filaroides the end organ atrophies. In the gut of the definitive host plerocercoid II increases in size and develops a metascolex and modified protonephridial system, before adult development ensues.
Eléments du comportement sexuel chez Pardosa xerampelina (Keyserling) (Araneida : Lycosidae)
Authors: Dumais J. , Perron J.-M. , Dondale C. D.
Published: January 2008

Courtship in male Pardosa xerampelina is stimulated by a contact sex pheromone laid down by the female, though visual cues also play a part. There is a short period of immobility, followed by the extension and raising of the pedipalps, one after the other. The male then makes a short run toward the female, his tarsi making an audible sound on the substratum. This sequence is repeated one or more times until the male is very close to the female, when he drums on the substratum (also producing a sound), taps the legs and cephalothorax of the female with his anterior legs, and mounts at once.
Eimeria nieschulzi infections in inbred and outbred rats: infective dose, route of infection, and host resistance
Authors: Liburd Eugene M.
Published: January 2008

Some of the host–parasite interrelationships between Eimeria nieschulzi (Protozoa: Sporozoa) and inbred and outbred strains of rats, were analyzed. The sex of the host did not influence the severity of infection; however, starved rats as compared with fed ones produced significantly lower numbers of oocysts during an infection. Mechanical crushing of infected faeces yielded a significantly higher number of oocysts than those crushed manually. The reproductive potential of the parasite varied inversely with the dosage of oocysts. Infections were caused by parenteral injections of sporozoites through four routes. In every case these inoculations caused milder infections than those elicited by similar doses of oocysts or sporozoites given orally. All infections stimulated resistance in rats; the intensity of this immunity was dose dependent. Single doses of 2500 and 3500 oocysts or more induced total resistance in outbred and inbred rats, respectively. This immunity was demonstrated 15 days after inoculation, by challenge infections. No developing stages were found in the intestinal tissues of rats which were immunized and then challenged.
An automatic ultrasonic sensing system for monitoring the activity of some bats
Authors: Fenton M. B. , Jacobson S. L. , Stone R. N.
Published: January 2008

An electronic system for monitoring activity of some echolocating bats in the field is described. An ultrasonic receiver is used to detect the bat cries. Audiofrequency signals from the receiver are processed and converted by the system to characteristic marks on the chart of an event recorder. The utility and limitations of the technique with respect to the echolocating characteristics of bats and analysis of recorder charts are considered. Quantitative data obtained in several habitats with this system are presented.
Patterns of alkaline phosphatase activity during alternative developmental pathways in the cellular slime mold, Polysphondylium pallidum
Authors: O'Day Danton H. , Francis David W.
Published: January 2008

The enzyme alkaline phosphatase (EC 3.1.3.1) was studied during axenic growth, microcyst differentiation and fruiting body formation in the cellular slime mold Polysphondylium pallidum. The enzyme activity decreases during growth and microcyst differentiation but increases during fruiting body formation where it is localized in prestalk cells. Two major isozymes exist for the enzyme and these change qualitatively and quantitatively during multicellular development. Beryllium was found to be a potent inhibitor of the slime mold phosphatase. When beryllium was added to growing cells or cells undergoing fruiting body formation markedly reduced alkaline phosphatase activity was detectable in the cells but growth and development were unaffected. The results are discussed in relation to other work on the cellular slime molds.
Observations sur le cycle vital et la croissance d'Amnicola limosa (Say) (Mollusca, Gastropoda, Prosobranchia) du lac Saint-Louis près de Montréal
Authors: Pinel-Alloul Bernadette , Magnin Etienne
Published: January 2008

Amnicola limosa (3546 specimens) collected from July 1968 to July 1969 in four sampling areas of lake St-Louis have allowed us to describe briefly the life history and growth of this little studied species.
Buoyancy and aerial respiration: factors influencing the evolution of reduced swim-bladder volume of some Central American catfishes (Trichomycteridae, Callichthyidae, Loricariidae, Astroblepidae)
Authors: Gee John H.
Published: January 2008

Swim-bladder volume of nine species of Central American catfishes from four families was measured and found to be very small. In seven species it supported less than 5% of the body weight in water. Seven of the nine species were found to breathe air and the volume of gas in the accessory respiratory organ varied between species, supporting from less than 5% to more than 80% of the body weight in water. In only one of these species was there gas in the accessory respiratory organ in both normoxic and hypoxic water and only in this species did the organ have a definite hydrostatic function. The remaining air-breathing species used aerial respiration only in hypoxic water and there were differences between species in frequency of gulping for air and in partial pressure of oxygen in the water at which gulping was initiated. The evolution of a reduced swim-bladder volume appears to have been in response to a demersal mode of life.
Fat reserves in snow buntings
Authors: Vincent J. , Bédard J.
Published: January 2008

Snow buntings (Plectrophenax nivalis) were kept in outdoor and indoor aviaries in Quebec City for 2 years (1970–1972) to study some aspects of their behaviour in winter. Birds kept in isolation or in groups of 2, 4, or 12 individuals were weighed daily at sunset between November and April and once a week during the rest of the year. A very great spring premigratory fattening occurs in early March, relating to the precocity of the spring migration and to the absence of prebreeding molt in this species.Weight changes were related to environmental factors (day length, snow cover, temperature, etc.) over the winter months and to social conditions encountered in captivity. No correlation with current air temperatures was found but day length and snow cover correlated well with weight; however, the relationship was variously modulated by the social surroundings. Poorly identified social factors seemed to play a more important rôle than that played by any single environmental factor selected. Paired birds kept outdoors are considered to represent fairly well the pattern for wild buntings. There was no evidence that social thermoregulation (by huddling) was necessary for this species under Quebec City's winter climate.
Production of coccidiosis using oocysts, sporocysts, and sporozoites of Eimeria zuernii, E. contorta, and E. nieschulzi
Authors: Stockdale P. H. G.
Published: January 2008

Oocysts, sporocysts, and sporozoites of Eimeria contorta and Eimeria nieschulzi given to rats and the same components of Eimeria zuernii given to calves all produced patent infections. Oocysts of the two rodent species produced nearly twice as many fecal oocysts as did the equivalent number of sporocysts and sporozoites. No such difference in fecal oocyst output of calves fed oocysts, sporocysts, or sporozoites of E. zuernii could be inferred from statistical analysis of the results.
Individual sibling recognition in juvenile Canada geese (Branta canadensis)
Authors: Radesäter T.
Published: January 2008

Results from choice experiments indicate that a juvenile Canada gosling is able to recognize members of its own sibling group when only a few days old.
A review of the mermithid parasites (Nematoda: Mermithidae) described from North American mosquitoes (Diptera: Culicidae) with descriptions of three new species
Authors: Ross J. F. , Smith S. M.
Published: January 2008

Romanomermis Coman, 1961 is resurrected from the synonymy of Eurymermis Müller, 1931, the generic description is augmented, and three new species are described: Romanomermis kiktoreak, R. hermaphrodita, and R. culicivorax. R. culicivorax is a segregate of a complex known previously as Reesimermis nielseni Tsai and Grundmann, 1969. R. nielseni is restricted to a species known only from Wyoming. Reesimermis Tsai and Grundmann is suppressed and R. nielseni s.str. is transferred to Romanomermis. Reesimermis muspratti Obiamiwe and Macdonald is moved to Octomyomermis Johnson. Keys are provided for the world species of Romanomermis and for the described mermithids that infect mosquitoes in North America. A brief commentary is included on the taxonomic utility of length and degree of fusion of the spicules, body shape, cuticular fibres, and double molt to adult.
Effects of photoperiod and temperature on abnormal wing-pad development in two species of Odonata
Authors: Ingram Byron R.
Published: January 2008

Nymphs of the damselflies Enallagma hageni and Enallagma aspersum were collected in North Carolina from August or September to March and subjected to long- and short-day photoperiods at 16 and 21 °C. Abnormal wing pads frequently developed in the later instars of both species under daylength–temperature combinations that induced extra molts and slow growth from the middle instars to emergence. Abnormal wing pads were formed only at the higher temperature, primarily under short-day conditions, where extra molts were generally more numerous and growth was usually slower than under long days. Abnormal wing pads occurred under long days at 21 °C only in the early experiments, when extra molts were common; growth was also slow under these conditions. Mortality was considerably higher in nymphs with abnormal wing pads than in those undergoing normal development. The absence of abnormal wing pads at 16 °C compared with 21 °C suggests that even small temperature alterations, such as those resulting from discharges of heated water, may have adverse effects on the development of some aquatic insects.
Growth responses of cohabiting ciliate protozoa to various prey bacteria
Authors: Taylor William D. , Berger Jacques
Published: January 2008

Four species of ciliate protozoans isolated from a small pond were grown monoxenically on eight species of bacteria. Four of the bacterial species were common "laboratory" species, the others were isolated from the same pond as the ciliates. The ciliates showed different growth responses to the wild bacteria, confirming the hypothesis that they were specialized with respect to the bacterial species on which they could grow. The laboratory bacteria all permitted good growth of all ciliates, suggesting that the wild bacteria possessed mechanisms to discourage predation. The results are interpreted as supporting the concept that food specialization may be part of a niche partitioning that accounts for the high species richness observed in protozoan communities.
Histochemistry and ultrastructure of pre- and post-ovulatory follicles in the ovary of the goldfish, Carassius auratus
Authors: Nagahama Y. , Chan K. , Hoar W. S.
Published: January 2008

Pre- and post-ovulatory follicles in the goldfish ovary were investigated histochemically and ultrastructurally. Special cells in the thecal layer of preovulatory follicles of yolk-laden oocytes showed 3β-hydroxy-Δ5-steroid dehydrogenase (3β-HSD; EC 1.1.1.145) activity typical of steroid hormone synthesis. Ultrastructurally, these thecal cells possess organelles characteristic of steroid-producing cells: mitochondria with tubular cristae and agranular endoplasmic reticulum. Unlike thecal ceils, the granulosa cells contain organelles typical of protein-secreting cells. These findings strongly suggest that only the special theca cells are sites of estrogen synthesis in the goldfish ovary.Postovulatory follicles, 6–10 h after ovulation, were characterized by a highly vascular thecal layer and hypertrophied granulosa cells. A weak but definite 3β-HSD activity occurs in both special theca cells and granulosa cells. Ultrastructurally, the granulosa cells contain many lipid droplets and numerous Golgi elements, suggesting the possible immediate transformation of granulosa cells to lutein cells during the ovulation. However, 30 h after ovulation, both granulosa cells and special theca cells showed advanced degenerative features and these data do not seem to support the hypothesis of an endocrine role for the older postovulatory follicles of the goldfish.
The crop as an organ of glyceride absorption in the American cockroach, Periplaneta americana L.
Authors: Hoffman A. G. D. , Downer R. G. H.
Published: January 2008

The potential of the crop to absorb the products of triglyceride hydrolysis was investigated in the American cockroach, Periplaneta americana. Isolated sacs of crop and midgut tissue were filled with test loads containing [1-14C]palmitic acid or glyceryl tri[1-14C]palmitic acid and the efflux of label monitored. Label from both preparations was recovered primarily from the free fatty acid fraction. Inclusion of midgut lipase enhanced the rate of 14C efflux from test loads containing labelled triglycerides. Comparison of the relative rates of 14C efflux from crop and midgut sacs shows that the greatest efflux occurs from midgut, although the crop possesses the potential to effect absorption of significant amounts of hydrolysed triglyceride. The capacity of crop to absorb fatty acids was confirmed by monitoring the evolution of 14CO2 from insects in which the crop was ligated anterior to the proventriculus before they were fed a test meal containing [1-14C]palmitic acid. Ligated insects evolved 41.5% of the 14CO2 produced by non-ligated insects.
Seasonal loss of alarm substance cells in North American cyprinoid fishes and its relation to abrasive spawning behaviour
Authors: Smith R. Jan F.
Published: January 2008

Histological examination of skin from preserved specimens of nine species of cyprinoids and one catastomid revealed seasonal loss of alarm substance cells in the males from seven cyprinoid species and reduction in the females from two species. Six of these species have abrasive spawning behaviour, while the behaviour of the seventh species has not been extensively studied. This is taken as tentative evidence that seasonal alarm substance loss is related to abrasive spawning behaviour. Several species also show seasonal changes in mucus production and epidermal thickness.
The upper frequency limit of ringed seal hearing
Authors: Terhune J. M. , Ronald K.
Published: January 2008

The upper frequency-discrimination limits of two ringed seals were estimated by examining each seal's ability to differentiate between constant frequency and frequency-modulated pulses. The upper frequency limit was found to be 60 kHz for both seals. As a result, in the frequency range above 60 kHz pitch and spectral content information will not be differentiated.
A review of the Chitty Hypothesis of population regulation
Authors: Krebs Charles J.
Published: January 2008

Populations do not increase without limit, and one of the central problems of population biology is to explain why. The self-regulation hypothesis states that indefinite increase in population density is prevented by a change in the quality of the population. Changes in quality may be physiological or behavioural, genotypic or phenotypic, and three different mechanisms of self-regulation have been proposed: (1) the Stress Hypothesis suggests that mutual interactions lead to physiological changes, phenotypic in origin, that reduce births and increase deaths. (2) The Behaviour Hypothesis suggests that mutual interactions involving spacing behaviour prevent unlimited increase and that spacing behaviour is not an inherited trait. (3) The Chitty Hypothesis, or polymorphic behaviour hypothesis, postulates that spacing behaviour limits population density and that individual differences in spacing behaviour have a genetic basis and respond to rapid natural selection.The testability of the Chitty Hypothesis is examined with regard to 13 predictions that are explicit in Chitty's writings or derived by subsequent workers. Many of the predictions are not unique to the Chitty Hypothesis and only a few difficult manipulations adequately test Chitty's proposed mechanism to the exclusion of all others.Four population studies are reviewed with reference to the Chitty Hypothesis. While the detailed mechanism proposed by Chitty is not yet adequately tested in any population, his general belief that both behaviour and genetics are relevant to understanding population problems is now assumed by the new generation of population biologists.
Differential responses of biotypes of the pea aphid, Acyrthosiphon pisum (Harris), to a chemically defined diet
Authors: Srivastava P. N. , Auclair J. L.
Published: January 2008

Four clones of the pea aphid, Acyrthosiphon pisum (Harris), collected from different regions in North America (St-Jean and Ile-aux-Coudres, Quebec, in Canada, and New Mexico and Kansas in the United States) were reared on an aseptic chemically defined diet and characterized into biotypes. The clones from St-Jean and Kansas appeared similar and represent one biotype, whereas those from New Mexico and Ile-aux-Coudres were different from each other, as well as from St-Jean and Kansas. Third-generation larvae were produced only by biotypes St-Jean and New Mexico; however, none of them reached the adult stage.The amount of diet ingested and its utilization by different clones also varied. In 24 h, the total diet ingested by flrst-instar larvae from St-Jean, Kansas, New Mexico, and Ile-aux-Coudres was 164,140, 112, and 65 μg per aphid respectively. During the same period the larvae increased their weights by 28, 13, 10, and 10% respectively. Total, or percent increase in weight, was however not proportional to the amount of diet ingested, thus reflecting on the relative efficiency of diet utilization by different clones.
Experimental studies on factors limiting colonization by Daphnia pulex Leydig of coastal montane lakes in British Columbia
Authors: Neill William E.
Published: January 2008

Laboratory and field experiments were conducted lo account for the absence of a widespread and locally abundant zooplankter Daphnia pulex From oligotrophia monlane lakes in coastal British Columbia. Water quality, food concentration, and invertebrate predation were examined as potential limiting factors. Laboratory exposure of neonate and adult D. pulex to montane take water and lowland pond water, both manipulated to the same range of seston densities, revealed significant effects of food levels and water sources. Elevated food levels consistently produced marked increases in survival, growth, and reproduction compared with natural, low seston densities. Further, enhancement effects were always lower in water from montane lakes. Laboratory predation by Chuobarux trivittutus larvae over a range of natural prey densities showed heavy predation only in the absence of normal alternative prey. Large-scale field experiments in 10 000-ℓ enclosures in a montane lake produced high invasion success by D. pulex after artificial fertilizer additions and modest invasion success in the absence of Chuoborus predation. Invasion was unsuccessful at natural seston densities when Chaoborus was present.These results suggest that food limitation, coupled with unspecified water quality effects and low levels of Chaoborus predation, limits D. pulex invasion potential, despite numerous nearby sources of dispersers.
Ultrastructure of putative steroid-producing cells in the gonads of coho (Oncorhynchus kisutch) and pink salmon (Oncorhynchus gorbuscha)
Authors: Nagahama Yoshitaka , Clarke W. Craig , Hoar W. S.
Published: January 2008

The testes of coho and pink salmon apparently contain both interstitial (Leydig) cells and lobule boundary cells. The interstitial cells possess cellular organelles characteristic of steroid-producing cells (large mitochondria with tubulovesicular cristae and an extensive agranular endoplasmic reticulum). The lobule boundary cells contain large sudanophilic lipid droplets and some features suggestive of phagocytotic functions. Thus, the interstitial cells are presumably responsible for testicular androgen production, and the lobule boundary cells are considered homologous with mammalian Sertoli cells.Ovarian follicles of mature oocytes contain a special cell type in the thecal layer. These special cells possess organelles characteristic of steroid-producing cells. The granulosa cells do not show convincing evidence of steroidogenesis. Postovulatory follicles consist of a highly vascular thick thecal layer and degenerated granulosa cells. The special thecal cells often form clusters consisting of several cells and seem to retain their secretory activity. Thus, the special thecal cells are the possible sites of ovarian steroid hormone synthesis.
The influence of food availability on the white-footed mouse: populations in isolated woodlots
Authors: Hansen Lonnie , Batzli George O.
Published: January 2008

The density and demography of populations of the white-footed mouse (Peromyscus leucopus) were monitored in two isolated woodlots for 29 months. After 14 months of preliminary trapping, supplemental food was provided on one woodlot for 15 months; the other remained as a control. Supplemental food had little influence on spring and summer densities although the onset of reproduction in spring was earlier and breeding occurred at a younger age in the experimental woodlot than in the control woodlot. Supplemental food strongly influenced autumn and winter densities, which reached much higher levels on the experimental plot than on the control plot. Higher densities were associated with better survival of nestling mice.Summer densities were limited by decreased survival and increased dispersal of young, and these were most closely correlated with densities of adult females. Therefore we suggest that summer densities were regulated by aggressive female behavior. In autumn the behavior of adult females changed, as indicated by a significant increase in home-range overlap among adult females, and both survival of young and total population densities increased. This behavioral change appears to be an adaptation to a seasonal change in predictability or food supplies. Unpredictable mast crops may provide either abundant or sparse food supplies in autumn, and neither can be defended efficiently.
The population dynamics of aphids on fire weed: a comparison of local populations and metapopulations
Authors: Addicott John F.
Published: January 2008

Local populations of four species of aphids (Macrosiphum Valerianae, Aphis varions, A. helianthi, and A. salicariae) occur on shoots of fireweed (Epilobium angustifolium) in the Rocky Mountains of Colorado, U.S.A. Through exhaustive and repeated nondestructive sampling of the local populations on over 3800 shoots of fireweed, information was obtained on the dynamics of both the local populations and the metapopulation of each species. The dynamics of the metapopulation were analyzed in terms of the frequency of shoots occupied by aphids and the median number of aphids per occupied shoot. There were significant differences between species in both parameters, but high densities were not necessarily accompanied by high frequencies. Local populations were initiated throughout the summer, and there was marked variation in the duration and size of these populations. Most populations lasted only a few weeks, but others lasted up to 14 weeks. This turnover of local populations within the metapopulation implies that local populations must be studied in order to understand the dynamics of the metapopulation. There is a discussion of the relationships between population processes occurring at different levels of spatial heterogeneity.
Temporal synergism of cortisol and prolactin influences salinity preference of Gulf killifish, Fundulus grandis
Authors: Fivizzani Albert J. , Meier Albert H.
Published: January 2008

Salinity preference was determined in male Fundulus grandis during different seasons and after several experimental treatments. The percentage of time spent by individual fish within six compartments along a horizontal salinity gradient was monitored by photographing the position of the fish every 5 min for 6 h. Feral Fundulus grandis preferred water of greater salinity during November (mean salinity preference = 22.2 ± 3.2‰) than during June (13.2 ± 2.6‰). Daily injections of prolactin were carried out for 8 days at 0 or 12 h after daily injections of cortisol in fish kept in continuous light in order to simulate daily rhythms of the endogenous hormones present in fish under winter or summer conditions, respectively. The 0-h relation of hormone injections promoted preference for water of greater salinity (23.9 ± 1.2‰) compared with the 12-h relation (15.7 ± 2.2‰) and with uninjected (15.8 ± 2.3‰) or saline-injected (13.6 ± 2.8‰) controls. Seasonal changes in salinity preference appear to involve a shift in phase relations of the circadian rhythms of cortisol and prolactin.
The life history of Cyclops scutifer Sars (Copepoda: Cyclopoida) in a small lake of the Matamek River System, Quebec
Authors: Boers J. J. , Carter J. C. H.
Published: January 2008

A study of the life history of the cyclopoid copepod Cyclops scutifer Sars in a small lake of the Matamek River System, Quebec, indicates a 1-year life cycle with four cohorts produced annually. The primary cohort overwinters as early nauplii and reaches maturity during midsummer when it spawns the primary cohort of the succeeding year. The other cohorts may merge with either each other or the primary cohort and contribute somewhat less to the overall cycle. Slower development of copepodites of the second cohort in 1976 may have been the result of an inadequate number of naupliar prey from the calanoid copepod Diaptomus minutus.
The functional significance of song sharing in the White-crowned Sparrow
Authors: Baptista Luis F.
Published: January 2008

The functional significance of learning a dialect has been a matter of considerable controversy. Some believe that birds learn dialects and mate assortatively according to those dialects to fixate adaptive genes within a habitat (the assortative mating theory). Others believe that birds learn dialects at sites settled after dispersal from their natal deme and that learning these songs gives them some kind of social advantage (the social adaptation theory). Color-marked female White-crowned Sparrows (Zonotrichia leucophrys) did not sing the same dialect as their consorts, and thus did not support the assortative mating theory. Birds singing alien dialects often mated and bred successfully. Hand-raised nestlings learned songs from live tutors but not from tapes when older than 50 days of age, beyond the age of dispersal. Critical examination of the literature revealed that there is no good evidence for restricted gene flow between dialect boundaries either from banding or isozyme studies. There is some evidence for birds changing dialects after dispersal from their natal area. Most available evidence tends to support the social adaptation theory.
Pathogénie, cycle de développement et ultrastructure d'Amblyospora culicis n. sp. (Protozoa, Microspora), parasite du moustique Culex quinquefasciatus Say, 1823 (Diptera, Culicidae)
Authors: Toguebaye Bhen Sikina , Marchand Bernard
Published: January 2008

Amblyospora culicis n. sp. is a new microsporidian parasite of the mosquito Culex quinquefasciatus Say, 1823 (Diptera, Culicidae). It infects the adipose and nervous tissues of male and female larvae and adults, as well as the ovaries of adult females. The observed meronts have, in turn, one, then two diplokaryons constituted of diploid nuclei. The sporogony is pansporoblastic and octosporous. At first, diplokariotic meronts transform into diplokaryotic presporonts bounded by a wall. Then, the plasma membrane of the presporont detaches itself from the wall, thus creating a pansporoblastic vacuole. A new wall appears around the presporont which thus becomes a sporont. Its two nuclei separate from each other, then the cytoplasm divides to form two uninucleate sporonts. Each then undergoes two meiotic divisions which end in the formation of eight uninucleate and haploid sporonts. These sporonts evolve into sporoblasts, then into spores. The spores are ovoid, uninucleate, and haploid (8.55 ± 0.13 × 6.46 ± 0.08 μm). They are bounded by a wall having a thick multilayered exospore and contain a polar filament abruptly constricted in its coiled part.
Response of rainbow trout (Salmo gairdneri) embryos to current flow in simulated substrates
Authors: Nunan Christopher P. , Noakes David L. G.
Published: January 2008

Direction of current flow did not affect the movement patterns of rainbow trout embryos maintained in artificial substrate systems. Embryos successfully emerged from the substrate in total darkness, although light has previously been implicated as necessary for emergent behaviour. Neither phototactic or rheotactic behaviour appears necessary for "normal" movement and emergence of salmonid embryos. Movement patterns appear to be primarily due to geotactic–geokinetic behaviour.
Paracellular ion transport in trout opercular epithelium models osmoregulatory effects of acid precipitation
Authors: Marshall William S.
Published: January 2008

The opercular epithelium of brook trout, isolated in vitro in Ussing-style membrane chambers, is used to model the effects of acid precipitation on ion balance in fish. The epithelium normally has a low permeability to sodium, chloride, and mannitol, consistent with the barrier function of the skin. Treatment of the outside surface of the epithelium with low pH (threshold pH = 3.9) reversibly reduces transepithelial resistance (Rt). Reduction of outer pH to 3.61 ± 0.05 decreases Rt and increases the efflux of ions (Na+ and Cl−) and uncharged solutes, indicating that the epithelium rapidly and reversibly becomes leaky to solutes. Simultaneous mannitol and ion fluxes indicated that a common pathway, in which the solutes moved in relation to their free solution mobilities, is opened by low pH. The results are best explained by the acid-induced opening of a simple water-filled paracellular pathway. Low pH also altered the shape of nonlinear current-voltage relations, reducing the current density required to effect a reduction in Rt. The results are consistent with a model in which the titration by low pH of Ca2+ away from structural sites in the apical "tight" junctions weakens the intercellular junctions, thus leading to increased paracellular ion permeation. The effect may account in part for increased ion loss that leads to the morbidity of fish in soft-water acidic environments.
Distribution of and notes on blackfly species (Diptera: Simuliidae) found in the major waterways of southern Alberta
Authors: Shipp J. L.
Published: January 2008

Twenty-one blackfly species from 22 rivers and creeks and 3 additional species from small temporary streams were collected in southern Alberta from 1981 to 1983. Eight Prosimulium, 14 Simulium, 1 Twinnia, and 1 Stegopterna species were identified. The collection of Prosimulium dicum Dyar and Shannon is the first record for Alberta. Simulium verecundum Stone and Jamnback, Simulium vernum Macquart, and Stegopterna mutata Malloch are first records for southern Alberta.
Distribution and population fluctuations of wintering Snowy Owls (Nyctea scandiaca) in North America
Authors: Kerlinger P. , Lein M. Ross , Sevick Brian J.
Published: January 2008

Christmas Bird Count data from 1952 to 1981 were used to examine the geographic distribution and population fluctuations of wintering Snowy Owls (Nyctea scandiaca) in North America south of the breeding range. Wintering owls were most abundant and regular in occurrence in the northern Great Plains and Midwest regions of North America. To the south of these locales, and on both east and west coasts, owl abundance averaged 10–100 times lower and varied dramatically from year to year. Numbers of Snowy Owls fluctuated synchronously within the east coast area, the west coast area, and possibly the Great Plains, but fluctuations were not synchronous among these three areas. Time-series analyses did not support the hypothesis of cyclic winter invasions. Earlier studies from eastern North America included only a small portion of the continental population of Snowy Owls and, consequently, their conclusions may have been biased. Our findings strongly suggest that Snowy Owls may not be cyclic invaders, but rather are regular migrants over much of their winter range.
A summer benthic survey in Conception Bay, Newfoundland, emphasizing zoogeography of annelids and amphipods
Authors: Kennedy Victor S.
Published: January 2008

A limited benthic survey was made in August in Conception Bay, Newfoundland, using a 0.2-m2 van Veen grab sampler. Nine stations were sampled in a relatively shallow (62–79 m), soft-bottom (predominantly silt) region with low bottom water (0.2–1.4 °C) and sediment (0.5–2.0 °C) temperatures. Annelids (32 species) and amphipods (18 species) were the common invertebrates collected, with annelids being more numerous, both in numbers of individuals and of species. Deposit-feeding annelids outnumbered carnivores, with subsurface deposit feeders more abundant than surface feeders. Sedentary individuals predominated. Most annelid species had boreal–temperate affinities, with few arctic species being present. Detritivorous amphipods predominated, followed by scrapers and scavengers. Nearly all were burrowers. All the amphipod species were arctic–boreal in distribution and most do not range as far south as do the annelids. Molluscs were small and uncommon and they, like the remaining uncommon components of the biomass, were not identified to any extent.
Urotricha vitrea n. sp. (Ciliophora, Prorodontina): General morphology and cytological events during the conjugation process
Authors: Martín-Gonzalez Ana , Serrano Susana , Fernández-Galiano Dimas
Published: January 2008

A new species of gymnostome, Urotricha vitrea n. sp., is proposed. The morphological characterization of this new freshwater ciliate is as follows: 46–27 μm × 43–26 μm in size; a spherical macronucleus; 20–23 somatic kineties; a caudal cilium; brosse with 4, 3, 2 rows of pairs of kinetosomes; and circumoral infraciliature with 13–16 pairs of kinetosomes. In addition, the conjugation process of this species is reported. It includes three maturation divisions and three synkaryon divisions.
The nervous system of a pilidium larva: evidence from electron microscope reconstructions
Authors: Lacalli T. C. , West J. E.
Published: January 2008

The principal ultrastructural features of a pilidium larva from Friday Harbor (pilidium A, unidentified as to species) are summarized and, based on electron microscope reconstructions, the larval nervous system is described for the first time. Ciliary effectors in the larva include the marginal ciliary band, which is drawn out to form a small accessory ridge at each of the junctions between lobes, and a pair of suboral (buccal) ridges, one on either side of the stomodeum, that run between the mouth and marginal band. The nervous system consists of a small intratrochal nerve supplying the marginal band, an oral nerve that encircles the mouth at the junction of stomodeum and stomach, and a pair of nerves connecting these that run beneath the suboral ridges. The nerve fibres appear to arise from uniciliate cells in the marginal band and the suboral region. The organization, innervation, and behavior of pilidium A are discussed briefly with reference to Müller's larva, a related larva with a similar type of trochal innervation.
The effect of apparatus, extraction time, and solvent type on lipid extractions of snow geese
Authors: Dobush Gloria R. , Ankney C. Davison , Krementz David G.
Published: January 2008

Variability in apparatus, solvent type, and extraction time for lipid extractions is common in the literature. To investigate the effect of this methodological variability on the amount and type of material extracted, equal subsamples of snow goose (Chen caerulescens) homogenate were extracted in Soxhlet and Goldfisch fat extractors with petroleum ether, diethyl ether, chloroform–methanol, and a petroleum ether–chloroform–methanol mixture for 3, 6, 12, and 24 h. The type of solvent used had the largest effect on the amount of material that was extracted. Petroleum ether and diethyl ether extracted few nonlipids, but chloroform–methanol extracted relatively large amounts of nonlipids. We conclude that chloroform–methanol, when used in a Goldfisch or Soxhlet fat extractor, is an inappropriate solvent for studies dealing with body composition.
Behavioral interactions between the actinian Tealia piscivora (Anthozoa: Actiniaria) and the asteroid Dermasterias imbricata
Authors: Elliott Joel , Dalby Jr. James , Cohen R. , Ross D. M.
Published: January 2008

Interactions between the sea anemone Tealia piscivora and the sea star Dermasterias imbricata have been studied in the laboratory and in subtidal habitats. Dermasterias causes the release of the pedal disk of smaller T. piscivora. The response is specific. Nineteen other sea stars did not cause release; four other species of Tealia did not respond to Dermasterias. The response is size dependent; unfailing and quick in small T. piscivora, less frequent and slow in those of intermediate size, it did not occur at all in large specimens. Unrestrained T. piscivora generally survived interactions with Dermasterias but when prevented from detaching, most of the small anemones were devoured. Tealia piscivora have been observed to detach and engulf small Dermasterias. Most small anemones were found at greater depths; most large anemones were found at lesser depths where Dermasterias were most abundant. It is suggested that by releasing the pedal disk, small T. piscivora eventually end up in deeper water where there are few Dermasterias and thus the anemones escape predation.