bluuebunny/crossref_metadata_2025 huggingface dataset:
Physical injury due to injection or blood removal causes transitory elevations of plasma thyroxine in rainbow trout, Salmo gairdneri
Authors: Brown Scott , Fedoruk Katherine , Eales J. G.
Published: August 2008

A transitory 100–200% increase in plasma thyroxine (T4) occurs within 2 h of either blood sampling from caudal vessels or saline injection into coelomic or cardiac regions of rainbow trout anaesthetized in methane tricaine sulphate (MS 222). Plasma 3,5,3′-triiodothyronine (T3) does not usually increase and may decrease slightly. MS 222 anaesthesia does not contribute to the response, which is believed to be caused by physical injury above a certain threshold.Physical injury does not modify the peripheral metabolism of labeled T4 as judged by its deiodination, enterohepatic excretion, or liver uptake, and it is concluded that the plasma T4 response is due to increased thyroidal discharge of T4. This view is supported by the marked elevation of plasma T4 but negligible change in plasma T3 following bovine TSH injection.It was also shown that plasma T4 and T3 levels of 1-year-old trout starved for 3 days do not exhibit significant diurnal cycling, do not vary between sexes, but are correlated with body weight.
Humidity behaviour and reception in the sphaeromatid isopod Gnorimosphaeroma oregonensis (Dana)
Authors: Standing Jon D. , Beatty D. D.
Published: August 2008

This study examined the humidity behaviour of the sphaeromatid isopod Gnorimosphaeroma oregonensis and tested the hypothesis of an osmotic or ionic mechanism of humidity reception. This intertidal isopod often inhabits air-exposed microhabitats having high relative humidities, and movements away from these microhabitats are prevented by orientation mechanisms. Gnorimosphaeroma oregonensis orients behaviourally in experimental humidity gradients. In a gradient of 76–100% relative humidity at 20 °C, the animals aggregated in high-humidity areas by a 'reversal turn' reaction occurring in lower humidity areas and possibly by a negative hygroorthokinesis. Klinokinetic orientation was not demonstrated.In testing the hypothesis of an internal osmotic or ionic mechanism of humidity reception, it was found that animals acclimated to 100% seawater had higher response intensities and lower activity rates than 25% seawater acclimated animals. These results suggest that humidity information may be received by receptor cells or neurons that are sensitive to osmotic or ionic concentrations of the body fluids.
The freshwater calanoid and cyclopoid copepod Crustacea of Cuba
Authors: Smith Kristin , Fernando C. H.
Published: August 2008

Based on the study of over 200 Zooplankton samples from five of the six provinces in Cuba, 26 species of freshwater Calanoida and Cyclopoida were recorded. Of these 23 are new records for Cuba. Brief remarks are made on some of the lesser known or unexpected species. The zoogeographical relationships of the Cuban species are commented upon. The fauna appears to be more tropical than temperate in this subtropical country.
Glucose-6-phosphate dehydrogenase and 'malic' enzyme activities during adaptive hyperlipogenesis in migratory starling (Sturnus roseus) and white wagtail (Motacilla alba)
Authors: Shah R. V. , Patel S. T. , Pilo B.
Published: August 2008

The changes in the activities of glucose-6-phosphate dehydrogenase and 'malic' enzyme in the liver and adipose tissue were studied in two migratory birds, viz., rosy pastor and white wagtail, which have different dietary habits during their post- and pre-migratory periods. Activities of both the enzymes in the liver of these birds increased during their premigratory period which correlated well with premigratory hyperlipogenesis. It is suggested that hyperphagia, diet, and hormones are involved in induction of the enzyme activities and premigratory hyperlipogenesis. Data on enzymatic studies indicate that 'malic' enzyme catalyzed reaction plays a major role in generation of NADPH2 and the liver is the main site for lipogenesis in these birds.
Competition for mutualists: aphids and ants
Authors: Addicott John F.
Published: August 2008

Evidence is presented which supports the hypothesis that competition occurs among species of aphids for the services of ants. It is suggested that, in addition to the more familiar pollination systems, aphid–ant systems should be used for the study of competition for mutualists because aphid–ant systems have both a significant advantage and important differences with respect to pollination systems.
Juvenile hormone biosynthesis by the corpora allata of the male desert locust, Schistocerca gregaria, during sexual maturation
Authors: Avruch L. I. , Tobe S. S.
Published: August 2008

The time course of release of C16 juvenile hormone (JH III) from isolated corpora allata (CA) of male Schistocerca gregaria was followed at selected times during sexual maturation. The rates of JH release over an 8-h incubation period were observed to be directly related to the age of the animals: CA from younger animals showed low rates of release (days 5 and 8) whereas CA from older animals showed intermediate to high rates of release (days 12–13). The mean rate of JH release is linear for at least 4 h. The only biosynthesized JH which could be detected in the incubation medium by radio gas–liquid chromatography was C16JH.The dry weight of the accessory reproductive glands (ARG) was also followed during the period of sexual maturation. This increased rapidly between days 10 and 15 and leveled off thereafter. The biosynthesis of C16JH, as determined by a radiochemical assay in vitro, also increased during this period, suggesting a functional relationship between synthesis of ARG secretion and JH.
Seasonal changes in the histology of the gonads and dorsal skin of the fathead minnow, Pimephales promelas
Authors: Smith R. J. F.
Published: August 2008

In central Saskatchewan gonad weights of male and female fathead minnows reach peak values between June 1 and July 31. The precise timing of the peak seems to be determined by local weather (temperature). Gonad histology shows a predominance of early gametogenic stages during winter with gametogene sis being completed in the spring. The histology of the dorsal skin is similar in both sexes during the nonbreeding season but males develop a dorsal pad during the breeding season. Pad development involves seasonal changes in epidermal thickness, mucous cell number, and dermal connective tissue thickness. Males also lose their alarm substance cells briefly during the peak breeding period.
Développement larvaire et bilan d'utilisation d'énergie en fonction de l'hygrométrie chez Tinea pellionella L. (Lepidoptera : Tineidae)
Authors: Chauvin G. , Gueguen A.
Published: August 2008

We studied the ability of the case-bearing clothes moth (Tinea pellionella L.) larva to develop in a dry environment and we examined the strategy developed by this species to survive under dry conditions. In a dry environment the larval development was characterized by a high level of mortality and a reduced growth rate. The weight of the fully grown larva was twice as low at 5% relative humidity (RH) as at 95% RH. The consumption index was higher at 5% RH than at 95% RH but the oxygen consumption per day was unchanged. For the same quantity of food ingested, oxygen consumption was higher at 5% RH than at 95% RH. The digestibility of ingested food was low under dry conditions and the efficiency with which digested food was converted to body substance was much reduced at 5% RH. A large proportion of digested food was utilized by the larva for water production. In spite of a high energy extraction efficiency, the larval production was greatly reduced in a dry medium because of the low efficiency of storage of metabolizable energy. In a dry environment the amount of energy required for water production is so large (24% of ingested energy) that it does not allow optimal development; only survival is possible under these conditions.
A test between relationships based on phenetic and cladistic taxonomic methods
Authors: McAllister Don E. , Coad Brian W.
Published: August 2008

Applying the axiom that hybridizing taxa are, on the average, more closely related than non-hybridizing taxa, a test was devised to evaluate differing methods of determing relationships. A measure of relationship called the cladistic coefficient was created to express the cladistic relationships of Willi Hennig's school of taxonomy and a program in BASIC was written to calculate it. The cladistic coefficient and the simple matching coefficient of numerical taxonomy were calculated for 304 sympatric pairs of genera of North American Cyprinidae using 10 two-state and 18 multistate characters using additive binary coding with 0 for primitive and 1 for advanced states. Fifty of these pairs hybridize.The proportion of simple matching coefficients for hybridizing genera above the mean coefficient, 62%, was not significantly higher than for non-hybridizing genera, 54%. For the cladistic coefficient the proportion of values for hybridizing genera above mean coefficient, 72%, was significantly higher, p < 0.0001, than for non-hybridizing genera, 32%.The cladistic coefficient provided a better measure of phylogenetic relationships than did the simple matching coefficient. The method, which can use indices of relationship other than hybridity, may be used to choose between conflicting classifications or differing taxonomic approaches.
The frontosquamosal arch in newts as a defence against predators
Authors: Naylor Bruce G.
Published: August 2008

The bony frontosquamosal arch, found in most newts, is suggested to function in lessening injury during attack by predators. The arch strengthens the skull, protects the retracted eyes, and correlates with postcranial defensive structures. Newts also have tetrodotoxin in the skin, and this is probably the ultimate factor in the evolutionary development and maintenance of the arch. Cranial strengthening in anurans with poisonous or distasteful skin probably serves a similar function.
The metacercaria of Galactosomum phalacrocoracis (Trematoda: Heterophyidae) from pink salmon, Oncorhynchus gorbuscha, from British Columbia waters
Authors: Pearson J. C. , Margolis L. , Boyce N. P.
Published: August 2008

The metacercaria of Galactosomum phalacrocoracis (Trematoda: Heterophyidae), collected from Oncorhynchus gorbuscha (Walbaum) from coastal waters of British Columbia, is described.
Helminth parasites of wolverine, Gulo gulo, from the District of Mackenzie, Northwest Territories
Authors: Addison Edward M. , Boles Bruce
Published: August 2008

Trematodes (Alaria sp.), cestodes (Taenia martis (Zeder 1803), Taenia twitchelli Schwartz 1924, and Diphyllobothrium sp.), and nematodes (Physaloptera sp. (?) and Baylisascaris devosi (Sprent 1952)) are reported from wolverine, Gulo gulo, from the District of Mackenzie, Northwest Territories, Canada.
Evaluation of polyethylene samplers for black fly larvae (Diptera: Simuliidae), with particular reference to Maine species
Authors: Boobar L. R. , Granett J.
Published: August 2008

Abilities of two types of polyethylene samplers to collect black fly larvae were compared with ceramic fireplace tiles, Surber samplers, and Hess samplers. The polyethylene samplers were colonized as well as tiles and were superior to bottom samplers for sampling black flies. The percentages of each species collected from polyethylene samplers were comparable with natural vegetation. Simulium penobscotensis Snoddy and Bauer and Simulium nyssa Stone and Snoddy, which do not readily colonize tiles, were collected by the polyethylene samplers in numbers similar to those collected by vegetation.
Comparative volumes and vascular microanatomy of the intrahepatic venous system of the harbour porpoise, Phocoena phocoena (L.)
Authors: Hilton J. W. , Gaskin D. E.
Published: August 2008

The intrahepatic venous systems of the harbour porpoise, Phocoena phocoena, were studied using single and double injection techniques. Large band-like formations of elastin fibres were found in the dilated terminal portions of the major hepatic veins and the adjacent section of the caudal vena cava but not in the equivalent major branches of the thicker walled portal veins. The hepatic venous system increases in volume disproportionately with increase in body length and liver weight; the portal system does not. No distal sphincter formations were found in the major hepatic veins, nor were sphincters or valves present in the portal system. The vena cava, however, is surrounded by a loop of diaphragmatic muscle or 'caval sling,' which may cause significant occlusion of the vena cava following inspiration. The distensible terminal portions of the major hepatic veins and the adjacent portion of the caudal vena cava could then function as a temporary blood reservoir or 'intrahepatic sinus.' While this would be a relatively inefficient mechanism for preventing ventricular engorgement, it might be sufficient for the needs of P. phocoena, which is a relatively poor diver.
Cellular mechanisms of periostracum formation in Physa spp. (Mollusca: Pulmonata)
Authors: Jones G. M. , Saleuddin A. S. M.
Published: August 2008

The periostracum comprises an external lamella, 13 nm thick, and one sublamellar layer. Periostracal cells secrete the lamella as preformed periostracal units. The mantle edge gland (meg) produces most of the sublamellar layer. A sequence of formation of periostracal units within the periostracal cells is suggested. Homogeneous inclusions, possibly Golgi derived, fuse into larger, irregular inclusions. Within these inclusions, three-layered membranes, 7 nm thick, arise from the homogeneous material. The membranes fuse in pairs to form the five-layered, 13-nm periostracal units. Acid phosphatase activity has been localised al the surfaces of the periostracal units and might be involved in modifying the units prior to their discharge. Phenoloxidase and polyphenols have been localised in the meg, suggesting that this region is responsible for periostracal sclerotisation. Phenoloxidase activity is present in Golgi, rough endoplasmic reticulum, and apical secretory inclusions in cells in the anterior two-thirds of the meg. Polyphenols are present in apical secretory inclusions, particulary in three or four cells in the posterior meg. This distribution may suggest that phenoloxidase is incorporated into all levels of the sublamellar layer and that sclerotisation occurs subsequently when the enzyme substrate is presented.
A search for behavioural variation in first and last laid eggs of western tent caterpillar and an attempt to prevent a population decline
Authors: Myers Judith H.
Published: August 2008

Earlier studies of western tent caterpillars reported that female moths deposit eggs so that the first eggs are laid at the top of the mass on a sloping branch. The first laid eggs are described as having greater nutrient stores and producing more active larvae. Based on these descriptions, field tests were conducted in which 'active' tent caterpillar groups were constructed by combining the first laid halves (upper halves) of two egg masses and 'less active' groups composed of the last halves of the egg masses. Contrary to expectation, the groups of caterpillars arising from first laid eggs had neither better success nor did they produce larger tents than the last laid eggs. Laboratory behaviour tests conducted concurrently showed that unlike earlier studies, larvae from first and last laid batch halves were equally active in this population.
Daily cycles in serum gonadotropin levels in the goldfish: effects of photoperiod, temperature, and sexual condition
Authors: Hontela Alice , Peter R. E.
Published: August 2008

The effects of temperature (12 and 21 °C) and photoperiod (16 h light, 8 h dark; 8 h light, 16 h dark) on daily cycles of serum gonadotropin (GtH) in goldfish with a regressed gonad (GSI = 1.1%), females undergoing ovarian recrudescence (GSI = 5.2%), and females with a mature gonad (GSI = 11%) were investigated. Serum GtH levels were measured by radioimmunoassay. Fish with regressed gonads either did not show significant daily fluctuations in serum GtH levels under different environmental regimes or showed daily fluctuations smaller in magnitude than those of females undergoing ovarian recrudescence or mature females. The patterns of daily variations of GtH levels under the same photoperiod and temperature regime were somewhat similar in the latter two groups. Also, under similar environmental conditions, although the GtH levels of females undergoing ovarian recrudescence and mature females were higher than the GtH levels in fish with regressed gonads most of the time during the 24-h period, during a portion of the 24-h period the GtH levels of all three groups were similar.
A parasitological survey of the American lobster Homarus americanus from the Northumberland Strait, southern Gulf of St. Lawrence
Authors: Boghen Andrew D.
Published: August 2008

A parasitological survey was conducted on 233 lobsters from the Northumberland Strait. Routine macroscopic and histological examinations revealed that 93% were infected by one or more parasites. Parasites detected included a Spiruroidean nematode believed to belong to the genus Ascarophis, an unidentified flagellate, the annelid Histriobdella homari, and the sporozoan Porospora gigantea. The latter organism was by far the most common. Highest parasite frequencies occurred in lobsters whose carapace measurements exceeded 50 mm.
Description of Criconemoides pleriannulatus n.sp. (Nematoda: Criconematidae) and a key to the species of Criconemoides
Authors: Ebsary B. A.
Published: August 2008

Criconemoides pleriannulatus n.sp. from Russia is described and illustrated. It is differentiated from C. annulatus by a more posterior excretory pore, prominent conical vulval lips, flexible stylet, and by the first three retrorse annules. It differs from C. morgensis by having more body annules, longer stylet, hemispherical tail, and more posterior excretory pore. The male specimens identified previously as C. ratundicaudatus are correctly identified as Nothocriconema longulum. A key to the nominal species of Criconemoides is provided. New synonymy includes C. kamaliei = Macroposthonia bakeri; C. parakouensis = M. rotundicauda; C. fimbriatus = C. informis; C. kashmirensis = N. mutabile; C. dorsoflexus = M. curvata. Other changes include M. brevistyla comb.n., syn. C. brevistylus.
Cells of the thoracic defensive gland of the red-humped caterpillar, Schizura concinna (J. E. Smith) (Lepidoptera: Notodontidae): ultrastructural observations
Authors: Percy Jean , MacDonald J. A.
Published: August 2008

The thoracic defensive gland in larvae of Schizura concinna J. E. Smith consists of an anterior and posterior gland joined by an interglandular neck. Ultrastructural observations indicated that there are no cuticular ductules associated with gland cells and that there are three, or possibly four, types of cells within the gland. Two types, as suggested by their location, probably function to maintain the form of the orifice and the interglandular neck. The remaining cells, located in the anterior gland, the anterior lateral longitudinal folds, and the posterior gland exhibit no appreciable ultrastructural differences from each other. Only the cells of the lateral longitudinal folds contain deposits of a lipid-like material. The apical plasma membranes of these cells have a peculiar array of folds surrounding cylinders of endocuticle. Within the apical folds these cylinders are encircled longitudinally by tubules which presumably arise from smooth tubular endoplasmic reticulum. Within the cuticle overlying the cells are filaments which are similar in appearance to the secretion contained within the lumen of the glands.
Southeastward shorebird migration over Nova Scotia and New Brunswick in autumn: a radar study
Authors: Richardson W. John
Published: August 2008

Shorebirds departed over the Atlantic intermittently by night and (in lesser numbers) day in late summer and early autumn. Migrations were broad-front and usually began inland (including Bay of Fundy), often 1–2 h before sunset. Tracks were straight, with daily means of 110–170° (overall mean 134°). About 69% were flying on tracks directed too far east to reach South America without a course change; the roles of wind drift and heading adjustments in effecting this course change are uncertain. Ground speeds were 74 ± SD 17 km/h; altitudes were often high (mean 2.0 km, 5% of flocks above 4.4 km, highest 6.65 km). Many departed with W–NW winds and fair weather behind cold fronts or E or N of high pressure areas, but some took off ahead of or caught up with and penetrated cold fronts. Mean tracks were correlated with wind direction, but were rarely downwind. Their deviation from downwind was unrelated to visibility, cloud, or magnetic disturbance (K index). Dispersion of tracks did not change consistently during nights or days and was unrelated to wind or K index. Dispersion at night was slightly greater in inclement than fair weather.
The free-living and parasitic development of Rhabdias spp. (Nematoda: Rhabdiasidae) in amphibians
Authors: Baker M. R.
Published: August 2008

Free-living development of Rhabdias americanus and Rhabdias ranae was heterogonic and development of infective larvae was by matricidal endotoky. Both species were experimentally transmitted by skin penetration. Development of R. americanus in Bufo americanus and R. ranae in Rana sylvatica was similar. Growth of third- and fourth-stage larvae occurred in fascia and muscle tissue of the host during migration to the body cavity. Adult worms were recovered only from the body cavity and lungs; larvae were never observed in these locations. Worms probably entered the lungs by direct penetration. Gravid nematodes were observed only in the lungs. Both R. americanus and R. ranae were transmitted to toad and frog tadpoles, respectively, and worms developed to adulthood in tadpoles. Terrestrial snails (Oxyloma decampi Tryon and Discus cronkhitei Newcomb) were demonstrated as possible paratenic hosts for R. americanus. Rhabdias americanus, which does not occur in frogs, and R. ranae, which does not occur in toads in the wild at Guelph, were experimentally cross-transmitted to these amphibians and developed successfully to adults. Infective larvae of these species, however, did not as readily penetrate into the unusual host as the usual host. It is suggested that ecological barriers have prevented cross infections in the wild.
Some aspects of the biology of Amphiporeia lawrenciana Shoemaker (Crustacea, Amphipoda) in Newfoundland waters
Authors: Downer D. F. , Steele D. H.
Published: August 2008

In Newfoundland waters 50% of female Amphiporeia lawrenciana mature at 7.5 mm. Between May and August a series of broods may he produced, but from August to October females enter the resting stage so that young are released from the brood pouch between May and November. Females reach a larger size than males and fecundity is moderate (F = 1.97L + 14.367 in winter, F = 1.33L + 11.855 in summer). Amphiporeia lawrenciana was least abundant in January and increased to a maximum in October.
Effect of TRH, TSH, and LH-RH on plasma thyroxine and triiodothyronine in the lesser snow goose (Anser caerulescens caerulescens) and plasma thyroxine in the Rouen duck (Anas platyrhynchos)
Authors: Campbell R. R. , Leatherland J. F.
Published: August 2008

The effect of TRH, TSH, and LH-RH on plasma thyroxine (T4) and triiodothyronine (T3) levels was studied in the lesser snow goose (Anser caerulescens c.) and on plasma T4 in the Rouen duck (Anas platyrhychos). LH-RH when given in doses sufficient to stimulate LH release demonstrated no thyrotrophic activity. TRH increased plasma T4 levels in the geese by 96% to 52 ng/mL within 20 min of treatment and levels remained high for up to 1 h. Return of plasma T4 levels to base-line levels appeared to take 80 to 90 min. TSH resulted in similar increases in plasma T4 within 15 min of treatment and produced maximum levels of 42 ng/mL in the male and 30 ng/mL in the female (329 and 266% increases, respectively). Peak plasma T3 levels lagged behind T4 peaks providing evidence that at least part of the T3 is foimed by peripheral monodeiodination of T4. The response of plasma T4 to TSH in the duck was similar to that in the geese although base-line levels were higher.
The seven larval instars of Prosimulium mixtum Syme and Davies and P. fuscum Syme and Davies (Diptera: Simuliidae)
Authors: Ross Douglas H. , Craig Douglas A.
Published: August 2008

Larval Prosimulium mixtum/fuscum pass through seven instars dearly segregated by postgenal lengths (P < 0.001). Total body lengths and number of cephalic fan rays differ significantly between instars one through six (P < 0.001), but not between sixth and seventh instars. However, the last two instars are separated by degree of development of the pupal respiratory organ. Scanning electron microscope examination revealed variations in the number of rows of hooks and hooks per row in the posterior circlet, hypostomial teeth, and in mouthpart structure. However, these three characters do not possess distinctly defined states and therefore are not diagnostic in separating all instars. Structural differences in mouthparts of the instars appear to be adaptations for different food-collecting habits, a phenomenon seen in certain species in other simuliid genera. A key to the seven larval instars of P. mixtum/fuscum is also presented.
A supplemental key to species of Helicotylenchus Steiner, 1945 (Nematoda: Hoplolaimidae) described since 1972 and a description of H. oscephalus n.sp.
Authors: Anderson R. V.
Published: August 2008

A parthenogenetic spiral nematode, Helicotylenchus oscephalus n.sp., collected from high elevations is described and illustrated. Its distinguishing characters are a hemispherical head with six to eight annules, a strongly sclerotized head skeleton with a deeply depressed septum, a sty let 25 to 28 μm long, hemizonid three to six annules anterior to the excretory pore, and a conoid, broadly rounded tail that is longer than the anal body width. A key is provided for 50 species of Helicotylenchus not included in existing keys.
Comparable activities of left and right corpora allata consistent with humoral control of juvenile hormone biosynthesis in the cockroach
Authors: Weaver R. J.
Published: August 2008

The rates of juvenile hormone (JH) biosynthesis have been measured in vitro for individual members of the paired corpora allata (CA) in the cockroach Periplaneta americana during the first two reproductive cycles. A marked similarity of endocrine activity between left and right glands of the majority of animals was observed, even though total JH biosynthesis by the gland pairs can differ up to 200-fold during this period. In a small number of immature females only one gland in the pair had the capacity to synthesize hormone. These results support the use of 'split pairs' of CA from mature, adult female P. americana in short-term in vitro radioassay of potential exogenous and endogenous modulators of JH biosynthesis, such that each sample bioassayed has a valid control. Furthermore, the observations suggest that, after a short postecdysial period (up to 4 days), the CA of this species are controlled by one or more humoral factors.
Water content, weight change, and activity of apterous and alate virginoparous Acyrthosiphon pisum (Harris) (Homoptera: Aphididae)
Authors: MacKay P. A. , Downer R. G. H.
Published: August 2008

Changes in weight, water content, and activity of alate and apterous virginoparous Acyrthosiphon pisum (Harris) were observed during development from third instar larvae to mature adults. Apterous aphids gained weight steadily until the 4th day of adulthood, and showed no dramatic changes in activity during this period. The live weights of alate aphids decreased during the 24 h immediately following the final moult, but increased gradually after this lime. The onset of weight loss occurred before the active nonfeeding period during which dispersal would normally lake place. Recommencement of weight gain followed the resumption of feeding. After the adult moult, the water content of alatae expressed as a percentage of live weight decreased for 24 h. whereas that of apterae remained constant. During the next 24 h, the water content of alatae increased to a level slightly below that of apterae. Thereafter, both morphs maintained a constant water content until about the 5th day, when a slight increase was evident. Eighty-five percent of the weight loss of adult alatae is attributable to water loss. It is suggested that dehydration of newly moulted adult alatae is an adaptation to facilitate dispersive flight.
Reproductive change in the 10-year cycle of snowshoe hares
Authors: Cary John R. , Keith Lloyd B.
Published: August 2008

Reproduction was monitored during a 16-year study of snowshoe hare (Lepus americanus) populations near Rochester, Alberta. Pregnancy rate, ovulation rate, and litter size changed markedly between successive litters within the breeding season; these parameters were thus further categorized by litter in our analyses. Most reproductive components varied significantly between years; a significant '10-year' periodicity was the dominant source of this variation. The cyclic fluctuations of reproductive parameters were broadly synchronous and tended to precede the population cycle by about 3 years, thereby producing a range in potential natality annually of 7.5 to 17.9 young per female. The year-to-year variability of pregnancy rate, ovulation rate, and litter size was markedly larger in the later litters than in the early ones. Paunched weight, mean age, incidence of endoparasites, liver and spleen weights, and midwinter-to-spring weight change also possessed significant 10-year cycles; paunched weight cycled directly with the hare population, but the others cycled either directly with or counter to reproduction. We believe that the correspondence between midwinter-to-spring weight change and reproduction implicates winter nutrition as the primary cause of the cyclic variation. Onset of spring accounted for a significant amount of variability in onset of breeding, adding to that due to the periodic change.
Influence of diet composition on radiothyroxine kinetics in brook trout, Salvelinus fontinalis (Mitchill)
Authors: Higgs David A. , Eales J. G.
Published: August 2008

The peripheral metabolism of L-thyroxine (T4) labelled with 125I(*T4) was compared in two groups of 2-year-old brook trout maintained on a 12-h photoperiod at 11–12 °C and fed once daily for 31 days at a level of 2.2% of body weight with either a high protein, high calorie (HP–HC) or a low protein, low calorie (LP–LC) diet.Ingestion of the LP–LC diet decreased the plasma T4 level, reduced biliary–fecal excretion of *T4, depressed the monodeiodination of *T4 to labelled 3,5,3′-triiodo-L-thyronine (*T3), and lowered the T4 degradation rate. Trout fed this diet were also noted to have increased liver size and reduced terminal body weights relative to those fed the HP–HC diet.These data suggest that feeding a low protein, low calorie diet may depress thyroidal function, as well as the conversion of *T4 to *T3.
Gametogenesis and reproductive cycles in the sea anemone Anthopleura elegantissima (Brandt, 1835)
Authors: Jennison Brian L.
Published: August 2008

Reproduction in the sea anemone Anthopleura elegantissima was investigated in central California for 3 years. Gametogenesis of anemones from four sites is described, and annual reproductive cycles are compared at a harbor and protected outer coast site. Anthopleura elegantissima is dioecious, although one hermaphrodite was found. Spermatogonia arise in the endoderm of the mesenteries of males, migrate into the mesoglea, multiply, and differentiate into spermatozoa. In females, oogonia arise in the endoderm and migrate into the mesoglea where they undergo vitellogenesis. Spawning is synchronous within each population. Gamete growth is correlated with increasing temperature, and spawning occurs during periods of peak summer temperatures.
Thyroxine and duodenal development in chicken embryos
Authors: Brewer Linda M. , Betz T. W.
Published: August 2008

To test whether thyroxine (T4) can stimulate duodenal development in chickens, it was administered to 16.5-day-old embryos (strain Hyline 934F of Gallus gallus) (approximately stage 42). Treatment time was closer to the prehatching phosphatase increase, and the single dosage (5 μg) larger than before. Control groups received the following: (1) D-T4 for possible physicochemical variables, (2) windowed shells and saline vehicle, (3) windowed shells or (4) no treatment. Subsequent accumulation of duodenal alkaline phosphatase activity (EC 3.1.3.1) and protein content were monitored as developmental parameters (n = 8–43). Yolk sac retraction, distribution of developmental stages, and mortality were used as indices of maturation and survival. L-Thyroxine treatment increased duodenal alkaline phosphatase significantly (p < 0.01) within 48 h, 24 h sooner than normal. This precocious increase was transient in embryos treated at stage 41. Duodenal protein content was elevated significantly in stage 43 embryos treated with L-T4, but it was not different from control values at later stages. Pooling of time data did not greatly alter duodenal parameters. Yolk sac retraction and shell pipping began sooner in embryos treated with L-T4 than control embryos, however, distribution of developmental stages was unaltered. Increased mortality was found 72 h after L-T4 treatment. After D-T4 treatment no parameter was significantly different. The parameters responding after treatment may be stimulated by thyroxine during development.
Neighbor–stranger discrimination by song in male blue grouse
Authors: Falls J. Bruce , McNicholl Martin K.
Published: August 2008

Playback experiments demonstrated that male blue grouse tan distinguish the songs (hoots) of neighbors in the correct direction from those of other male blue grouse. Specific responses to playbacks of song differed among individuals, but each bird responded more strongly to songs of strangers than to those of neighbors. Responses to stranger playbacks were higher while responses to neighbor playbacks were lower using stranger–neighbor–stranger sequences as compared with neighbor–stranger–neighbor sequences.
Plasma calcium as an indicator of reproductive condition in female blue grouse
Authors: Hannon Susan J.
Published: August 2008

Measurement of total plasma calcium as an indicator of reproductive status of live blue grouse (Dendragapus obscurus fuliginosus) hens was assessed. Total calcium showed a high positive correlation to weight of oviduct and development of ovarian follicles. Hens with ovaries in the slow recrudescence phase could be readily distinguished from laying hens or those with ovaries in the rapid stage of recrudescence.
A multispecies aphid–ant association: density dependence and species-specific effects
Authors: Addicott John F.
Published: August 2008

In the central Rocky Mountains of Colorado 4 species of aphids feed on fireweed, and 10 species or ants have been observed tending 3 of these species of aphids. Local populations of aphids and their associated ants were counted nondestructively at weekly intervals for up to 11 weeks. The effects of ants upon the persistence of recently initiated populations and the growth of populations during 1-week intervals were assessed by multidimensional contingency table analysis. Macrosiphum valerianae, which is not tended by ants, was affected negatively by ants. Aphis varians and A. helianthi were affected by tending, but A. salicariae was not affected. The responses of both A. varians and A. helianthi to tending were density dependent; i.e., small populations that were untended were more likely to decrease than tended populations, but large populations that were tended were either more likely to decrease than untended populations or equivalent to them. Possible reasons for this density-dependent effect are discussed, and its implications for the stability of the mutualism between aphids and ants are considered. Different species of ants had different effects. Populations of A. varians that were tended by Formica neorufibarbis or Tapinoma sessile performed no differently than untended populations, but low-density populations that were tended by F. cinerea or F. fusca were less likely to decline than untended populations.
Effects of salinity on site selection by ovipositing Aedes togoi (Diptera: Culicidae)
Authors: Trimble R. M. , Wellington W. G.
Published: August 2008

Two ranges of salinities, 0, 5, 10, 20, 40, and 20, 25, 30, 35, 40 g NaCl/L were tested for their effect on oviposition site selection by colonized Aedes togoi. No preference was shown between distilled water and salt solutions of 5, 10, and 20 g NaCl/L, but females strongly avoided the 40 g NaCl/L solution. Females showed increased avoidance of salt solutions for oviposition as salinity increased from 20–40 g NaCl/L. These results are discussed in relation to similar studies with Ae. togoi and other mosquito species and in relation to embryonic and larval development of Ae. togoi.
Echinoid larvae from the northeast Pacific (with a key and comment on an unusual type of planktotrophic development)
Authors: Strathmann Richard R.
Published: August 2008

Larvae of all seven species of echinoids occurring in coastal waters from southern British Columbia to central California have been reared through metamorphosis. Larvae of Dendraster excentricus, Brisaster latifrons, and Strongylocentrotus franciscanus can be distinguished from all others by skeletal traits alone. Living larvae of Strongylocentrotus droebachiensis and Strongylocentrotus purpuratus can be distinguished from all others by color of pigment spots combined with skeletal differences. Larvae of Allocentrotus fragilis and Strongylocentrotus pallidus have similar skeletons and pigment spots of the same color, so it is difficult to identify specimens even if they are alive. A key is provided for identification of echinoplutei.Development of Brisaster latifrons is similar to that of Brisaster fragilis in the Atlantic. The development is unusual for echinoderms in that large eggs develop into large feeding larvae with a long pelagic period. Moreover, the juveniles formed at metamorphosis have about the same diameter as juveniles of echinoids with much smaller eggs but similar pelagic periods.
The histochemistry and endocrine control of vitellogenesis in goldfish ovaries
Authors: Khoo Khay Huat
Published: August 2008

Histological and histochemical examinations of goldfish ovaries indicate that two types of yolk inclusions are formed during vitellogenesis: first, yolk vesicles, comprised of mucopolysaccharides, followed by yolk granules composed of protein, phospholipid, and neutral lipids. Neither type of yolk develops in the absence of the pituitary. Estrogens regulate the formation of yolk vesicles, while pregnenolone was found to control the deposition of yolk granules. The significance of these two kinds of yolk is discussed. This is the first demonstration of a separate endocrine control for the formation of each of the two yolk types in goldfish ovaries.
Succession saisonnière, émergence, voltinisme et répartition de mouches noires des Laurentides (Diptera; Simuliidae)
Authors: Back C. , Harper P. P.
Published: August 2008

A study of the distribution and the emergence of blackflies in 33 stations in streams at the Saint Hippolyte Biology Station gives the following dynamic picture: (1) The main emergence starts in May with the appearance of the univoltine species that have grown through the winter, followed by the first generation of spring-growing or summer-growing polyvoltine species. The predominance of the eurytopic univoltine species, mainly Prosimulium fuscum and Cnephia mutata, explains the presence of blackflies in nearly all the stations. (2) In July the second generation of the polyvoltine species appears, Simulium decorum, S. vittatum, S. aureum, S. verecundum, S. croxtoni, and S. vernum; these species lend to be more stenotopic, which restricts emergence mainly to stations near lake outlets; the other stations harbour only small populations of S. tuberosum. (3) The same distribution is evident in late August and early September when the third generation of the polyvoltine species matures, particularly S. tuberosum, S. aureum, and S. verecundum. A wet and cool summer tends to favour the development of large populations of blackflies.
Parasite fauna of the muskrat, Ondatra zibethica (Linnaeus, 1766), in Manitoba, Canada
Authors: McKenzie C. E. , Welch H. E.
Published: August 2008

Seven trematode, three nematode, two cestode, one acanthocephalan, one protozoan, and three acarina species were recovered from 171 muskrats (Ondatra zibethica) taken in Manitoba. Thirty-one muskrats were examined for ectoparasites, 111 for endoparasites and 29 for both. Plagiorchis noblei and the nematode Heligmosomum carolinensis were recorded for the first time from the muskrat. Variation between the parasitic fauna of the four areas examined was not significant, probably due to the ease of dispersal of the host. Capillaria michiganensis and Hymentilepis sp. were significantly more prevalent in female muskrats than in males. Young muskrats were parasitized shortly after weaning, with the most prevalent parasites being acquired first.
Differential chromatic activity of melanophores in integumentary patterns of winter flounder (Pseudopleuronectes americanus Walbaum)
Authors: Burton Derek
Published: August 2008

Winter flounder chromatophores include three major melanophore systems with differences in effector distribution and chromatic behavior. Response characteristics suggest that each of these pattern components represents a different neuroeffector system and that there may he prolonged hormonal control. One pattern component has the capacity for rapid melanosome dispersion and a second has the capacity for rapid melanosome aggregation on different backgrounds. Chromatic behavior of the third component is not necessarily background related. Although epidermal and dermal melanophore responses both exhibit rapid and slow phases, greater degrees of melanosome aggregation occur in epidermal melanophores and a higher stimulation threshold for their melanosome dispersion is indicated.
Diel variations in circulating levels of triiodothyronine and thyroxine in goldfish, Carassius auratus
Authors: Spieler Richard E. , Noeske Teresa A.
Published: August 2008

Goldfish maintained on a 12 h light: 12 h dark photoperiod (light onset 0800 hours) and sampled at one of six different times of day had significant differences in both serum triiodothyronine (T3) and thyroxine (T4) levels depending on the time of day of sampling. Hormone titers were determined by commercial radioimmunoassay kits. Maximum levels for T3 and T4 occurred at 1600 hours; minimum levels occurred during the 4 h preceding the onset of light (0400- and 0800-hour samples). There was no apparent effect of sampling stress (< 15 min) on titers of T3 and T4.
Observations on the ontogeny of setae in the family Phytoseiidae (Acarina: Gamasina)
Authors: Rowell H. J. , Chant D. A.
Published: August 2008

The ontogenetic development of setae on the dorsum and venter of the idiosoma and on the legs is described for the following four species of Phytoseiidae: Amblyseius andersoni (Chant). Amblyseius degenerans (Berlese), Phytoseiulus persimilis Athias-Henriot, and Typhlodromus pyri Scheuten. Homologous setal relationships between successive instars are discussed. The larvae of additional species were examined to determine if there are consistent patterns of setal development in the Phytoseiidae. A standard system of nomenclature for the setae on the idiosoma is applied to the immature instars.
Retinal red pigment in the pickerel (Esocidae)
Authors: Nicol J. A. C.
Published: August 2008

The pigment epithelium in the eye of the pickerel Esox contains a red pigment. It is localized in tiny cylinders and granules, and it replaces melanin. From its characteristics (solubility, chromotography, ultraviolet–visible spectrum) it appears identical with retinal red pigment of characins and wrasses. A method of extraction is described.
The attachment of teeth in Lophius
Authors: Kerebel Lise-Marie , Cabellec Marie-Thérèse Le , Geistdoerfer Patrick
Published: August 2008

The mandibular teeth in Lophius present the two kinds of attachment typical of predatory bony fish: ankylosis and fibrous hinge. Light microscopy and microradiography showed that ankylosis, occurring through a gradual transition between basal dentine, attachment bone, and bone proper, is the most achieved type encountered in fish. The ligament of the hinge appeared to consist of collagen fibres exclusively. No elastic components were found. Ankylosis and hinged attachment in Lophius are merely levels in the mineralizing process of collagen fibres. The resilience of the dental apparatus is enhanced by the freely movable bone and cartilage of the jaws and pharyngeals, which allow ingestion of large prey, making up for the disadvantages of nonocclusion and reduced bony architecture.
Benthic species of Dorylaimus Dujardin 1845 (Nematoda: Dorylaimidae) and Arctidorylaimus n.gen. (Arctidorylaimidae n.fam.) from the Mackenzie and Porcupine river systems, Northwest Territories, Canada
Authors: Mulvey R. H. , Anderson R. V.
Published: August 2008

Arctidorylaimidae n.fam. and Arctidorylaimus n.gen. are proposed to accommodate A. arcticus n.sp., a dorylaimid with longitudinal body ridges from aquatic habitats. A diagnosis of the family and genus, key to closely related genera, and description and illustrations of the new species are provided. The main differential characters of these new taxa are the offset head, short, conoid tails in both sexes, and the spaced, mammillate supplements of the male. Dorylaimus lineatus, a new record for Canada, and Dorylaimus stagnalis are described from Canadian populations and their diagnostic characters compared and illustrated. The genus Dorylaimus is reviewed and a key, supplemented with tabulated characters and references, is provided for all valid species. Dorylaimus amplexor and Dorylaimus sulcatus are placed in species inquirendae.
Aspects of the fine structure of the dauer larva of the nematode Caenorhabditis elegans
Authors: Popham J. D. , Webster J. M.
Published: August 2008

Examination of the ultrastructure of the dauer larva of Caenorhabditis elegans showed that cells in the lateral cord and body wall muscle had irregular profiles, few Golgi bodies, and cisternae of endoplasmic reticulum, but they contained abundant lipid and glycogen. These cells and the esophageal cells had mitochondria in the condensed conformation. The intestinal lumen was small and the brush border was so compact that individual microvilli were difficult to discern. Intestinal cells had cytosomes with irregular profiles and unhomogeneous matrices. The striated layer was absent from the cuticle covering the lips and papillae. These ultrastructural features are correlated with the dauer larva's low metabolic rate, its resistance to toxic chemicals and to adverse environmental conditions, and its ability to detect food and to feed soon after exposure to a hospitable environment.
A survey of the intestinal helminths of waterfowl from New Brunswick, Canada
Authors: McLaughlin J. Daniel , Burt Michael D. B.
Published: August 2008

Between August 1967 and December 1969, 148 local and migrant waterfowl (13 species) collected in New Brunswick, Canada, were examined for intestinal helminths. Forty-six helminth species (28 Cestoda of which 6 remain unidentified to species; 13 Digenea; 4 Acanthocephala; and 1 Nematoda) were found, of which 34 occurred in local young during the summer and most were also found in migrant ducks during the fall. Eleven species were found in migrant hosts only, these being species which do not normally breed in the province. Thirty-one of the 35 helminth species found locally occurred in Anas rubripes, the most abundant local host, and this host presumably played the greatest role in the local circulation of these helminth species.