bluuebunny/crossref_metadata_2025 huggingface dataset:
Regeneration in Spirostomum ambiguum: effects of some metabolic inhibitors
Authors: Prusti Rabi K. , Reddy A. S. N. , Mookerjee Sivatosh
Published: December 2009

Inhibitors of RNA and protein syntheses like ethidium bromide and chloramphenicol caused profound delay in the regeneration of Spirostomum ambiguum, while potent mitotic poisons such as colchicine and mercaptoethanol showed only general injury to the cell. Use of cyanide, sodium azide, and iodoacetate further reveals that the energy for regeneration in ciliates like Spirostomum is most likely provided by glycolysis rather than aerobic respiration.
Notation of primary setae and pores on larvae of Carabidae (Coleoptera: Adephaga)
Authors: Bousquet Y. , Goulet H.
Published: December 2009

Based on a study of more than 75 species of Carabidae and six species of other coleopterous families, the ancestral system of primary setae and pores on carabid larvae is established, described, and illustrated. Problems associated with homology of these setae and pores between species studied are discussed and some are illustrated.
Sanguivory in leeches and its effects on growth, survivorship, and reproduction of Theromyzon rude
Authors: Davies Ronald W.
Published: December 2009

The trophic effects of the timing of the blood meals of Theromyzon rude on its population dynamics and life cycle were determined in the laboratory and compared with field data based only on the population size structure. It was found that a minimum of three full blood meals are necessary before T. rude reaches sexual maturity. The laboratory data show that the majority (> 80%) of the population take all three meals in the first 6 months after hatching. The remainder of the population overwinters after two meals and take their third meal in the spring so that all the population reproduces within approximately 12 months of hatching. Some individuals overwintering after three meals decline in weight to below 150 mg before spring and these individuals require a fourth blood meal before reproduction commences. After each blood meal there is a further increase in body weight as a result of water uptake. It is suggested that this dilution of the blood facilitates the faster digestive rates shown by T. rude compared with other sanguivorous species which rapidly eliminate water from their guts after feeding. Sanguivory in T. rude is compared with sanguivory in other Glossiphoniidae and Hirudinidae.
Dimorphisme sexuel et régime alimentaire de l'hermine dans un agrosystème du Québec
Authors: Raymond Michel , Bergeron Jean-Marie , Plante Yves
Published: December 2009

Variations in the diet of the ermin (Mustela erminea) were studied from 1978 to 1980 in relation to the relative availability of meadow voles (Microtus pennsylvanicus), the dominant mammal of Southern Quebec agrosystems. The analysis of 328 ermine scat samples showed that the vole does constitute the main prey item, but that the masked shrew (Sorex cinereus), the short-tailed shrew (Blarina brevicauda), and various birds are also important food components. Male ermins have more flexible feeding habits than females, who eat mostly meadow voles whatever their relative abundance. Both males and females fail to make full use of the shrews and avoid prey that weigh more than 50 g. Overlap of their realized alimentary niches is thus considerable except when small mammals are scarce. In that case, males and females use different feeding strategies; however, the hypothesis suggested by J. H. Brown and R. C. Lasiewsky (1972. Ecology, 53: 939–943) does not seem to be confirmed. The evolution of size dimorphism in this small mustelid is discussed; our results confirm the intra-sexual selection hypothesis proposed independantly by S. Erlinge (1979. Oikos, 33: 233–245) and P. J. Moors (1980. Oikos, 34: 147–158).[Journal translation]
Influence de l'effet de groupe et de la qualité de la plante-hôte sur le cycle évolutif de quatre biotypes du puceron du pois, Acyrthosiphon pisum
Authors: Auclair J. L. , Aroga Regine
Published: December 2009

The influence of aphid population density and excised leaves of broadbean, Vicia faba L., was evaluated on four biotypes of the pea aphid, Acyrthosiphon pisum (Harris); two of these originated from Quebec (J and C) and two from Europe (Lg and Lp). Results indicated that growth of the biotypes feeding singly on excised leaves was reduced compared with that obtained on broadbean plants. Furthermore, excised leaves induced wing formation in the progeny, which occurred in varying proportions, Lg producing the most alatae and C the least. When two young females were placed together on excised leaves for 20 h, the production of alatae in the progeny increased significantly in three biotypes; 95% in Lg, 47% in Lp, and 64% in C. When 10 females were similarly treated, no significant increase in alatae production was observed, except in J where it increased from 18 to 35%. The increased tendency by biotypes C, Lp, and especially Lg to produce more alates indicates a higher migratory potential, favouring multiple infestations of favorable host-plant areas, as well as a greater probability for plant virus dissemination. Clone J, on the other hand, appears more resilient and sedentary and capable of greater localized infestations of host plants.
Feeding ecology of age 0 pumpkinseed (Lepomis gibbosus) and black crappie (Pomoxis nigromaculatus) in the Ottawa River
Authors: Hanson John Mark , Qadri S. U.
Published: December 2009

The seasonal feeding patterns and feeding periodicity of age 0 pumpkinseed (Lepomis gibbosus) and black crappie (Pomoxis nigromaculatus) were investigated in the littoral zone of a small bay in the Ottawa River. Pumpkinseed attained a mean total length of 44.3 mm and black crappie 77.2 mm at the end of September 1978. Both species fed diurnally. Both fish species showed strong positive, curvilinear relationships between mean prey weight and fish weight. Pumpkinseed ate larger prey than black crappie of similar size despite black crappie having a proportionately larger mouth. The major seasonal prey of age 0 pumpkinseed were chironomid larvae and daphnids. Gastropods were important prey for pumpkinseed > 35 mm in length. The dominant prey of age 0 black crappie were calanoid and cyclopoid copepods. Fish fry were important prey for black crappie 15–30 mm in length. Chaoborus larvae were important prey of black crappie > 50 mm in length.
Foods of six species of sympatric shrews from New Brunswick
Authors: Whitaker Jr. John O. , French Thomas W.
Published: December 2009

Major foods of six species of sympatric shrews from Sagamook Mountain. New Brunswick, in order of importance by percentage of total volume were Blarina brevicauda: earthworms, slugs and snails, and insect larvae; Sorex palustris: insect larvae, spiders, slugs and snails, and flies; Sorex gaspensis: insect larvae, spiders, flies, and beetles; Sorex fumeus: insect larvae, earthworms, and moths; Sorex cinereus: insect larvae and spiders; Sorex hoyi: insect larvae, beetles, and spiders. These rather striking differences in the diets of the various species of shrews in this study suggest that the food resources were being differentially exploited.
Parasitic laying in nests of gadwalls
Authors: Hines James E. , Mitchell George J.
Published: December 2009

At Waterhen Marsh, Saskatchewan, at least 60 (17%) of 355 completed gadwall (Anas strepera) clutches were parasitized by other gadwalls (9%), lesser scaup (Aythya affinis) (8%). or both species (< 1%). Nests known to be parasitized by gadwalls contained on average at least 7 or 8 parasitic eggs while those parasitized by scaup contained an average of only 1.6 ± 0.2 (SE) parasitic eggs. Most parasitized nests were situated in areas of high nest density. Lesser scaup laid parasitically in gadwall nests located in shorter or sparser cover than most other nests, whereas nests parasitized by gadwalls were in vegetation similar to unparasitized nests. Assuming that nests parasitized by gadwalls contained > 14 eggs, intraspecific parasitism significantly reduced nesting success from 76 to 54%, egg success from 74 to 45%, and hatchability of eggs from 97 to 91%. Interspecific parasitism had no significant effect on nesting success or hatchability, but caused a slight decrease (74 to 67%) in egg success. The differential effect of lesser scaup and gadwall parasitism on host reproductive success was likely due to differences in numbers of parasitic eggs laid in the nest of the host by each species. We hypothesize that parasitism occurred because ducks did not continuously occupy the nest during laying, thereby allowing two or more females to lay eggs synchronously at the same site. Parasitic laying by gadwalls was possibly an anomaly, rather than true parasitism.
Diel pattern of plasma T3 and T4 levels in Baltic salmon parr (Salmo salar L.) during two seasons
Authors: Rydevik Magnus , Lindahl Kenneth , Fridberg Gunnar
Published: December 2009

In March (sunrise at 0530, sunset at 1800, water temperature 0.04 °C, and the fish not feeding) plasma T3 showed no diel variation and plasma T4 varied only slightly. In May (sunrise at 0200, sunset at 2120, water temperature 9.0 °C, and the fish feeding) plasma T4 showed a pronounced diel variation with its peak value appearing just before sunset and its nadir occurring at 0800. The plasma T3 level varied slightly with its peak value at 0400. The constant or slightly varying diel levels of plasma T3 suggests an efficient regulatory mechanism that maintains the plasma T3 concentration relatively stable throughout the 24 h. It is concluded that the diel patterns of T4 and T3 are dependent on factors related to the season. The influence of photoperiod and feeding on the diel pattern of T4 is discussed.
Sex chromosome polymorphism in the Simulium tuberosum complex (Lundström) (Diptera: Simuliidae)
Authors: Mason G. F.
Published: December 2009

These studies on the Simulium tuberosum complex have revealed the presence of a number of closely related sibling species which are distinguished by the banding pattern on their sex chromosomes. Collections were made over wide geographic areas of North America and the distributions of the various types found were recorded. Included are areas in northeastern United States with sites at which a number of the sibling species are sympatric. At these sites the separation of one taxa from another is not clear and a number of intra- and inter-sibling sex chromosome polymorphisms were detected. Included in these polymorphs were larvae with unusual chromosome combinations, including females with heteromorphic sex chromosomes. Arguments are made for some of the divisions as distinct species and for sex chromosome polymorphism in others. Based on the evidence of the geographic distribution, it is suggested that the area of sympatry in which polymorphism in all of the division of the complex was found is a primary zone of speciation.
Ultrastructural analysis of the midgut of Drosophila auraria larvae. Morphological observations and their physiological implications
Authors: Dimltriadis V. K. , Kastritsis C. D.
Published: December 2009

Electron and light microscopic examinations of Drosophila auraria larval midguts derived from insects of various stages of development show six clearly differentiated regions along its monolayered epithelium. Generally, the morphological data indicate that the cells of all these regions are involved in the elaboration and secretion of products in a manner that appears to follow the generally accepted scheme for these events. Among the six regions, the posterior and the anterior sections of the midgut are the regions that could be considered as the first and second most important sites, respectively, for terminal digestion and the absorption of nutrients. The middle midgut, on the other hand, in which long infoldings of the basal plasma membrane of the cells are observed, can be considered as a region of intense water transport between the hemolymph and the central lumen of the midgut.
The parasitic crustaceans of fishes from the Brazilian Amazon. 11. Vaigamidae fam. nov. (Copepoda: Poecilostomatoida) with males and females of Vaigamus retrobarbatus gen. et sp. nov. and V. spinicephalus sp. nov. from plankton
Authors: Thatcher Vernon E. , Robertson Barbara A.
Published: December 2009

Vaigamus retrobarbatus gen. et sp. nov. and V. spinicephalus sp. nov. (Copepoda: Poecilostomatoida) are described. The specimens were obtained by examining plankton samples from floodplain lakes of the Amazon River Basin in Brazil. The new genus is distinguished from all other genera and families in the suborder by the presence of retrostylets projecting laterally from the first thoracic segment and a long tapering rostral spine between the bases of the antennae. Vaigamidae fam. nov. is proposed for these forms. The two new species of the new genus are distinguished on the basis of the following characters. Size: retrobarbatus is larger than spinicephalus. Cephalothorax: that of spinicephalus is more ovoid. Pigment distribution: retrobarbatus had a broad transverse band of color on the cephalothorax while spinicephalus has a narrow band on the fourth thoracic segment. Rostral spine: spinicephalus has a spine with a subbasal swelling while that of the other species is smoothly tapering. Genital segment: that of retrobarbatus is more hexagonal. Antennal claw: in retrobarbatus the claw is longer than the third antennal segment while in the other species it is shorter. Leg 4: retrobarbatus has one fewer segment in each ramus than has the other species. Leg 6: that of retrobarbatus is longer.
The distribution and evolution of cavernicolous Ptomaphagus beetles in the southeastern United States (Coleoptera; Leiodidae; Cholevinae) with new species and records
Authors: Peck Stewart B.
Published: December 2009

New data show the presence of additional full-species taxa of cavernicolous Ptomaphagus beetles, bringing to 18 the number of troglobitic species in the southeastern United States. The new species are Ptomaphagus chromolithus and Ptomaphagus torodei; full species rank is given to P. solanum, P. fecundus, P. longicornis, and P. Julius; P. laticornis is resurrected from synonomy. Ptomaphagus nicholasi is placed in synonomy under P. hirtus. A phylogeny is proposed. A model of speciation is proposed with cave populations isolated during interglacials, and with probable overland dispersal and interpopulation contact during glacials.
Nematode parasitism in amphibians and reptiles
Authors: Baker M. R.
Published: December 2009

Nematodes of amphibians and reptiles comprise five main groups: Enoplida, Oxyurida, Strongylida, Ascaridida, and Spirurida. Systematics, geographical distribution, and host range point to parasitic relationships that extend well back into tetrapod history. Some parasite groups such as the Enoplida were acquired from other vertebrate groups by host transfer, a common theme in the evolution of new nematode taxa. Most nematodes of amphibians and reptiles, however, evolved primarily in these hosts. Oxyurida in reptiles and amphibians are more primitive than forms they gave rise to in mammals. They closely resemble the Oxyurida of invertebrates. Strongylida possibly evolved in Mesozoic archosaurian reptiles such as dinosaurs and early birds. They are now mainly parasitic in mammals, although distinct groups of strongyloids, trichostrongyloids, and diaphanocephaloids evolved in amphibians and reptiles, probably in the early Cenozoic. Ascaridida evolved in mid-Mesozoic or earlier amphibians and reptiles, and the most primitive representatives (Cosmocercoidea) are common today in anurans, saurians, and chelonians. From these the other superfamilies evolved. Survivors of the early radiations include primitive Heterakoidea in anurans and saurians, primitive Ascaridoidea in crocodiles, and Seuratoidea in a wide variety of all vertebrate subclasses. Most superfamilies of Spirurida evolved in mammals, birds or extinct groups. Forms in amphibians and reptiles, however, are at least Mesozoic in age.
Calcium and phosphorus balance in juvenile harp seals (Phoca groenlandica)
Authors: Keiver K. M. , Draper H. H. , Hadley M. , Ronald K.
Published: December 2009

Calcium and phosphorus balances were determined for juvenile harp seals fed two diets of Atlantic herring (diet 1: 0.8% Ca, 1.3% P; diet 2: 1.3% Ca, 1.6% P). The effects of three levels of intake and of feeding frequency were investigated. Calcium excretion (percent of intake) occurred mainly through the faeces (90% versus 2% in the urine). Phosphorus was excreted in major amounts through both faeces (39%) and urine (50%). The apparent absorption coefficients for dietary calcium and phosphorus were 10 and 61%, respectively, Faecal and urinary excretion and retention of calcium and phosphorus increased directly with their respective intakes. Differences in diet and feeding frequency had no significant effect on calcium or phosphorus balance. The data indicate that the calcium and phosphorus content of the diets was adequate but that the retention of these minerals was limited by all three levels of energy intake, despite the fact that the seals increased in standard length between 1 and 2 years of age at a rate similar to that reported for wild harp seals.
Seasonal levels of cortisol and thyroid hormones in intact and castrated mature male white-tailed deer
Authors: Bubenik G. A. , Leatherland J. F.
Published: December 2009

Plasma L-thyroxine (T4), triiodo-L-thyronine (T3), and cortisol concentrations were measured seasonally in castrated and intact mature white-tailed deer. Both intact and castrated bucks exhibited a statistically significant seasonal rhythm in plasma T4 levels. However, the overall values in the castrated bucks were about 15% lower than in intact animals. Seasonal changes in plasma T3 levels were only found in the intact bucks, with highest values in the April – May period. Two peaks (in June and October) of plasma cortisol were detected in castrated bucks, but only one peak (in the September–October period) was found in intact bucks. In a second experiment in which cortisol levels were measured in "excitable" and "calm" intact bucks, there was no noticeable seasonal rhythm of cortisol in the "excitable" group, but a clear seasonal pattern, with a distinct peak in the October–November period, in the "calm" animals.
Laboratory studies of the effects of Mollusca on alkalinity of their freshwater environment
Authors: Rooke J. Brian , Mackie Gerald L.
Published: December 2009

A series of aquaria containing various combinations of water, sediments, and molluscs was used to investigate the effects of molluscs on alkalinity of the water. Live molluscs acidified the water, and dead decomposing molluscs were associated with an increase in alkalinity in the aquaria. Aquaria containing dead molluscs had more stable alkalinity concentrations than other aquaria when all received additions of natural acid rain (pH 4.1). Nonmolluscan invertebrates liberated acid-neutralizing materials from the sediments but the source was quickly depleted. A hypothesis of temporal disjunction between periods of molluscan acid and base production is given which indicates a potential role for molluscs in the sources and cycling of carbonates in acidifying environments.
Endocrine and behavioral correlates of nesting in Canada geese
Authors: Akesson Thomas R. , Raveling Dennis G.
Published: December 2009

Frequencies of social behaviors of captive Canada geese (Branta canadensis moffitti) were compared with serum levels of androgens, estrogens, and corticosterone during two nesting cycles. Behavioral and endocrine patterns were examined for relationships with the timing of nesting. Androgen levels in reproductively active males were correlated with seasonal changes in the expression of a pair-bond behavior known as Cackling and less strongly with behaviors exhibited in an aggressive context. Estrogen levels in paired females were correlated with frequencies of behavioral responses to the mate's Cackling, and, in one year, with Mating Behavior. Correlation between corticosterone levels and behaviors was weak. Few behavioral changes were correlated with hormone variations in nonbreeding geese. Dominance relations were consistently linear among ganders prior to the incubation period. Correlation between average androgen levels and rank was significant in one year only. The timing of nesting was delayed in a newly formed pair and a pair that was renewed after 15 months of separation. Endocrine levels and behavioral performances of ganders of established pairs did not appear to have an accelerating or decelerating effect on the timing of the mate's reproductive effort, suggesting that the exact timing of egg laying was determined by attributes of the females.
Influence du pH du milieu au cours de la fécondation sur la survie embryonnaire de la carpe commune (Cyprinus carpio)
Authors: Roubaud P. , Gillet Ch. , Billard R.
Published: December 2009

The effects of environmental pH during fertilization in carp eggs were studied by measuring the percentage of prehatching embryonic survival. These effects, which may be delayed beyond epiboly, were the same when the treatments lasted 15 and 30 min after insemination, and they were not modified either by the addition of a physiological salt solution to the medium or by exposure of the eggs for 10 s before insemination. Among the six types of buffer used, phosphate buffers were particularly toxic which may indicate the role played by calcium during fertilization. Normal fertilization requires that the osmolarity of the medium be lower than or equal to 200 mosmol/kg. Beyond the limits of favorable pH values (7.2 and 9.6), egg tolerance decreased less rapidly in a weakly buffered medium than in a strongly buffered one. In such a medium, there was no resistance at pH 6.2 or 9.9.
Fish embryo culture: cardiac monolayers and contractile activity in embryo explants from the zebrafish, Brachydanio rerio
Authors: Laale Hans Willer
Published: December 2009

Stage 16+ axial isolates from embryos of the zebrafish, Brachydanio rerio (Hamilton-Buchanan), were separated from their yolk spheres and epidermis. Rhombencephalic level explants, with intact bilateral cardiac rudiments, were maintained in nutrient medium for 20 days at 24 ± 2 °C. All embryo cultures became attached to the culture substrate and underwent subsequent differentiation. Ten out of 25 explants showed bilateral migrations of determined but initially undifferentiated cardiac mesoderm. The progressive structural and functional differentiation of zebrafish cardiac monolayers and intact rudiments are described for the first time.
Structure and production of fish communities in tropical rain forest streams of northern Borneo
Authors: Watson Dwight J. , Balon Eugene K.
Published: December 2009

Tropical fish communities are often assumed to be more productive than temperate communities. To test this belief, fishes from tributaries of the tropical rain forest Baram River, Sarawak, Malaysia were quantitatively collected with a piscicide and production was calculated by the Ricker algebraic method. Temperature was not considered a major factor influencing production among different climatic regions since the average production in the Baram (76.7 kg∙ha−1∙year−1) was less than in temperate Grand River, Ontario (279.4 kg∙ha−1∙year−1) and Nida River, Poland (121.0 kg∙ha−1∙year−1). Analysis of physical habitat characteristics, community-structure variables, and production estimates from Baram streams indicated production was controlled mainly by nutrient limitations (P < 0.01) while close species packing maximized production by efficiently utilizing the limited resources available. In highly competitive and diverse communities, Baram fishes have probably developed specializations which make them particularly vulnerable to environmental perturbations or overexploitation. An estimated fish catch of 14.2–19.6 kg∙ha−1∙year−1 by Baram subsistence fishermen was already within the estimated range for maximum sustainable yield (7.9–20.9 kg∙ha−1∙year−1). Therefore, it is recommended that research on community ecology should precede expansion of artisanal fisheries.
Summer home range use by adult marten in northwestern Maine
Authors: Wynne Kathleen M. , Sherburne James A.
Published: December 2009

Home range and habitat utilization data for adult marten were gathered from May to September 1980 in northwestern Maine. Analysis of 455 radio locations of three postlactating females and two adult males showed that overall summer ranges averaged 2.9 km2 for females and 5.6 km2 for males, with females showing preferential use of softwood stands. The frequency distribution of activity radii differed during this period for females but not for males, while use of habitats did not change. Thirty-eight resting sites and dens were located; 6 of 21 sites used by females were identified as maternal dens. All resting sites used by males were in tree canopies, commonly in "witches brooms" (abnormal clumped growth of balsam fir branches caused by rust fungi). Den characteristics are discussed in relation to the presence and development of kits.
Seasonal food habits of marten in south-central Alaska
Authors: Buskirk Steven W. , MacDonald Stephen O.
Published: December 2009

Studies of the diet of marten (Martes americana) and the abundance and habitat associations of small mammals were conducted in south-central Alaska for 2 years. Marten were found to eat primarily arvicolid (= microtine) rodents. Other important food items were sciurid rodents, fruits, and birds. Strong seasonal variation in the importance of arvicolid rodents was associated with changes in their density as indicated by trapline capture success. Northern red-backed voles (Clethrionomys rutilus) dominated the diet of marten when they and other arvicolids were generally scarce, whereas tundra voles (Microtus oeconomus) and meadow voles (M. pennsylvanicus) were the primary prey when arvicolids were abundant. Arvicolid species exhibited strong differences in habitat associations and habitat niche breadth. Red-backed voles were found in a wide range of habitat types, but tundra voles and meadow voles were limited to herbaceous and low shrub meadow habitats, where they attained high local densities. Similarities in patterns of prey preference by marten among several North American sites are described. The effects of patterns of habitat use by arvicolid rodents on the food habits of marten are discussed.
Early morphological development of gills in smallmouth bass (Micropterus dolomieui)
Authors: Coughlan David J. , Gloss Steven P.
Published: December 2009

The morphological development of the gill apparatus in 11- to 180-day old smallmouth bass (Micropterus dolomieui) is described as seen by scanning electron microscopy. Filament protrusions without lamellae developed on the midregion of the gill arches in yolk-sac fry. Filament development progressed from the midregion of the gill arch toward the insertions. Secondary lamellae were first observed 15 days after egg fertilization when the fry became free swimming. Lamellae first appeared on filaments proximal to the gill arch and advanced distally. Proliferation of filaments and lamellae continued through at least the first 90 days of life. Filaments on the medial hemibranch of a holobranch were longer than those on the lateral hemibranch for at least the first 90 days. Filaments were alternately arranged between two hemibranchs of a holobranch. Substantial differences existed between gill developmental stage at hatching in smallmouth bass and that previously reported for salmonids. The dynamic nature of the developing gill indicated that quantitative descriptions of filament length, lamellar number and area, and total gill surface area requires examination of specimens at numerous different ages. This is the first morphological description of developing gills in a teleost fish based on observations by scanning electron microscopy.
The relationships among nuptial coloration, aggression, and courtship of male three-spined sticklebacks, Gasterosteus aculeatus
Authors: Rowland William J.
Published: December 2009

A method was devised, using several independent judges, to estimate the degree of nuptial coloration of male three-spined sticklebacks, Gasterosteus aculeatus. Using the color-state scores that resulted from this technique, territorial males were compared with respect to their coloration level and with respect to their responsiveness to live and dummy stimulus fish. These comparisons reveal a positive association between color state and responsiveness: brightly colored males tend to court (zigzag) and attack (bite) stimulus fish more vigorously than duller colored males do. Therefore, the degree to which a male three-spined stickleback's nuptial coloration is developed can be used to some extent to predict its responsiveness, with the particular category of response (courtship or aggression) dependent on the stimulus presented. A close association between zigzag and bite frequencies was also found, responsive males showing higher levels of both courtship and aggression than less responsive ones. These results are consistent with evidence pertaining to the hormonal control of nuptial coloration, courtship, and aggression and to the signal value of nuptial coloration in G. aculeatus.
Response of the sea urchin, Strongylocentrotus droebachiensis, to reduced salinities: importance of size, acclimation, and interpopulation differences
Authors: Himmelman John H. , Guderley Helga , Vignault Gilles , Drouin Guy , Wells Peter G.
Published: December 2009

Weight change, mortality, and neuromuscular coordination, as measured by righting time, were used to evaluate the resistance of Strongylocentrotus droebachiensis to hypoosmotic stress. Acclimation to a salinity of 24 or 25‰ decreased the righting time of urchins after 96 h of hypoosmotic stress. The effect of acclimation was the same for four size groups of urchins (10–15, 20–25, 34–37, and 50–60 mm in test diameter). A comparison of urchins from the St. Lawrence Estuary and from Nova Scotia, both acclimated to 24‰, showed that for the three larger size classes, the salinity at which there was a significant increase in righting time was lower for urchins from an estuarine environment than for urchins from the oceanic environment. The percentage weight gain following hypoosmotic stress increased with decreasing urchin size. For small urchins the increase was less marked after acclimation to 24‰. The mortality rates following these experiments showed that acclimation to a reduced salinity increased the tolerance to hypoosmotic stress, that urchins from the St. Lawrence Estuary were better able to withstand low salinities than urchins from Nova Scotia, and that small urchins were more sensitive to osmotic stress than large urchins. The latter was confirmed in a field experiment in which four size groups of urchins were kept in cages at a location exposed to periodic decreases in surface salinities.
Comparison of gut contents and assimilation efficiency of fourth instar larvae of two coexisting chironomids, Chironomus riparius Meigen and Glyptotendipes paripes (Edwards)
Authors: Rasmussen Joseph B.
Published: December 2009

Responses to experimental manipulation, behavioral observations, and tube morphology all suggested that Glyptotendipes paripes and Chironomus riparius from Stephenson Pond (near Calgary) have different feeding mechanisms, and that G. paripes was a filter feeder and C. riparius, a deposit feeder. This hypothesis was supported by microscopical analysis of gut contents of fourth instar larvae of the two species. Chironomus riparius guts contained mainly silt particles and microdetritus fragments, whereas G. paripes guts contained mainly planktonic diatoms and microdetritus, with very little silt present. The anterior midgut contents of G. paripes exhibited significantly greater loss on ignition than the anterior midgut contents of C. riparius; however, ignition loss from the posterior midgut was not significantly different between the two species. These results are consistent with the differences found by microscopical analysis and show that (i) the material ingested by G. paripes was of higher organic content (37.6%) than that ingested by C. riparius (30.2%), and (ii) G. paripes assimilated a higher portion (11.9%) of what it ingested than did C. riparius (5.9%). The differences in feeding mechanisms are probably of considerable significance in permitting these two species to coexist at the high larval densities sometimes present in small ponds.
Egg loss among spruce grouse inhabiting lodgepole pine forests
Authors: Boag David A. , Reebs Stéphan G. , Schroeder Michael A.
Published: December 2009

The loss of eggs from clutches deposited in simulated and natural nests of spruce grouse was investigated during the spring of 1983 in lodgepole pine forests of southwestern Alberta. Two-thirds of all clutches, both in simulated and natural nests, were partially or completely lost. Density of simulated nests had no impact on proportional loss. Evidence suggests that nests under a conifer-dominated canopy, in an area lacking extensive shrub coverage, and at distances greater than 15 m from trails were the most vulnerable to egg predators. We conclude that red squirrels were the principle predator destroying these clutches.
Histomorphic changes in the ovary during the estrous cycle of a wild rat, Bandicota bengalensis
Authors: Sahu Abhiram
Published: December 2009

Histomorphic changes in the ovary of Bandicota bengalensis were studied during various stages of the estrous cycle. The ovarian follicles were classified into nine size groups and their frequency distribution was determined for the different phases. In all the ovaries 70% of the follicles were nonantral and below 201 μm in diameter. During proestrus and estrus the ovary possessed the highest number of nonatretic follicles. The follicles ranging above 600 μm were absent at metestrus and diestrus. Preovulatory follicles (>700 μm) were present only during estrus, indicating ovulation during the night of the day of estrus. Excepting the 30- to 50-μm follicles, all other follicles were susceptible to atresia in the cycling rats. Maximum atresia was noticed in the 201- to 500-μm follicles. The number of atretic follicles was highest at diestrus and lowest at estrus. In the continuous diestrous rats, about 50% of the atretic follicles were in the range of 30–100 μm. Three recognizable types of corpora lutea were found in the ovary. The volume of the first and second type corpora lutea was highest at proestrus and estrus, respectively. Mean number of first and second type corpora lutea was 3.87 and 4.56, respectively, and thus about four ova ovulated per ovary during each estrous cycle in this wild rat.
Geographic and seasonal distribution of the infectious stage of Ceratomyxa shasta Noble, 1950, a myxozoan salmonid pathogen in the Fraser River system
Authors: Ching Hilda Lei , Munday D. R.
Published: December 2009

The infective stage of C. shasta was demonstrated to be present at two lower Fraser River sites. However, it was absent in the McGregor River, a tributary of the upper Fraser, and rarely present in the upper Fraser River near Prince George, B.C. Seasonally, the infective stage occurred in the lower Fraser River from late April to mid-November. In April 1983, 12% of 25 fish became infected with C. shasta, indicating a low onset of activity. In experiments in 1981, 10- and 20-day exposures of 216 juvenile chinook salmon resulted in increased infections of C. shasta, from 72 to 75% in May to 96 and 98% in July. Time to death decreased from a mean of 54 to 30 days from first exposure. In 1982, 5- and 10-day exposures resulted in deaths of 98% of 181 fish from August to November. Mean time to death increased from 27 to 48 days and was probably due to decreasing river temperatures. In November, 90% of the fish became infected at water temperatures of 4 – 6 °C.
Susceptibility of six Fraser chinook salmon stocks to Ceratomyxa shasta and the effects of salinity on ceratomyxosis
Authors: Ching Hilda Lei , Munday D. R.
Published: December 2009

Juvenile chinook salmon representing six stocks from the Fraser River drainage system were tested for susceptibility to the myxozoan pathogen, Ceratomyxa shasta. Of the six stocks tested, three were collected from the Nechako, Quesnel, and Clearwater rivers and three were hatchery stocks originating from Slim Creek and the Bowron and Birkenhead rivers. Of 302 fish exposed in August 1982, 95% became infected and died of ceratomyxosis. Susceptibility was high and time of death varied with the fish stock. High river temperatures during the 10 days of exposure and a high level of abundance of infectious C. shasta contributed to high mortalities of fish. Results of maintenance of infected fish in seawater indicated that ceratomyxosis is not attenuated and fish will continue to die after entering the estuarine environment.
Development and regression of the corpus luteum in grey seal (Halichoerus grypus) ovaries and its use in determining fertility rates
Authors: Boyd I. L.
Published: December 2009

Adult female grey seals were sampled at the Fame Islands at monthly intervals from November 1980 to October 1981. The distribution, size, and number of ovarian corpora were recorded in each case and blood samples were obtained for progesterone analysis. The concentration of plasma progesterone was about 6 ng/mL for most of gestation, including embryonic diapause, and rose to about 10 ng/mL during the final month. Progesterone declined sharply to less than 1 ng/mL at parturition. The size of the corpus luteum was constant throughout embryonic diapause, but after implantation it grew continuously until parturition. Following parturition, it regressed rapidly at first, forming a corpus albicans, and then more slowly, regression being arrested during the period of foetal growth of the following reproductive cycle. Most corpora albicantia had disappeared 1 year after their formation. Corpora albicantia may be useful indicators of reproductive history in grey seals, providing that allowance is made for the reproductive condition of females at the time of sampling and for several other possible errors which could arise. Retrospective calculation of reproductive statistics by more than 1 year using corpora albicantia is not valid for grey seals.
The patterns of mosquito emergence (Diptera: Culicidae; Aedes spp.): their influence on host selection by parasitic mites (Acari: Arrenuridae; Arrenurus spp.)
Authors: Smith Bruce P. , McIver Susan B.
Published: December 2009

In this study, the spatial and temporal patterns of emergence of mosquitoes in a temporary autumnal pool were related to parasitism by larvae of the mites Arrenurus kenki Marshall and Arrenurus angustilimbatus Mullen. There was differential mite parasitism among the sympatric mosquito species; both mite species had an apparent host preference for Aedes cinereus Meigen and Aedes excrucians (Walker). Only A. cinereus, Aedes diantaeus Howard, Dyar and Knab, and A. excrucians had a significant temporal overlap with the parasitic phase of the two Arrenurus species. Therefore, host availability was seasonally limited. Although the abundance of parasitic mites was greater on female than on male. A. excrucians over the total emergence period, there was no difference when the sexes were compared on each sample date. This was due to close temporal association of mite abundance and female emergence, rather than to the mites discriminating between the sexes. The spatial distribution of the mites within the pool was not closely related to that of any mosquito species.
Factors influencing host selection and successful parasitism of Aedes spp. mosquitoes by Arrenurus spp. mites
Authors: Smith Bruce P. , McIver Susan B.
Published: December 2009

Larval Arrenurus mites establish a phoretic association with pupal mosquitoes and wait for emergence of the adult upon which they feed. In the laboratory, four Aedes spp. were given equivalent exposure to larvae of Arrenurus angustilimbatus Mullen and Arrenurus kenki Marshall. For both species of mites, Aedes excrucians (Walker) and Aedes cinereus Meigen were less than half as likely to be parasitized than were Aedes communis (DeGeer) and Aedes punctor (Kirby). Both mite species were apparently equally attracted to all four mosquito species, but upon contact they were far less likely to remain in phoretic association with A. excrucians and A. cinereus. Aedes cinereus displayed an avoidance response that reduced the number of phoretic mites by a factor greater than 10 while the larval mites would swim away from pupal A. excrucians in over 85% of the contacts. Larval A. angustilimbatus had differential success when transferring to the adult mosquito host (59.2% success on A. excrucians, 48.7% on A. punctor, 37.6% on A. cinereus, and 31.8% on A. communis). Once attached, the mites' engorgement success was almost 100% on all host species.
Studies on the in vitro formation of periostracum in Helisoma duryi: the influence of the dorsal epithelium on calcium incorporation
Authors: Kunigelis S. C. , Saleuddin A. S. M.
Published: December 2009

Mantle collar tissue was found to produce periostracum when placed in vitro. The rate of shell deposition in vivo was reflected in the in vitro rate of periostracum formation. The addition of whole brain from fast-growing donors to mantle collar from slow-growing animals was found to increase the amount of periostracum produced in vitro. This effect was further enhanced by removing the cerebral ganglia lateral lobes prior to incubation. The presence of dorsal epithelial tissue was found to increase the incorporation of calcium into periostracum formed in vitro.
Attempts to find a laboratory host for Parelaphostrongylus andersoni and Parelaphostrongylus odocoilei (Nematoda: Protostrongylidae)
Authors: Pybus M. J. , Samuel W. M.
Published: December 2009

Twenty guinea pigs (Cavia porcellus) and eight domestic rabbits (Oryctolagus cuniculus) were each exposed to 100 or 200 third-stage larvae of Parelaphostrongylus andersoni or Parelaphostrongylus odocoilei. A few larvae penetrated the stomach and caecal walls and were found in the mesentery, liver, and diaphragm. However, most were recovered from the lungs and pleurae of the pleural cavity. Larvae did not appear to grow or develop and they did not reach the skeletal muscles, the usual site of adult P. andersoni and P. odocoilei in deer. All larvae in tissues were encapsulated (after 36 days) and overcome (after 59 days) by a local host response. Larvae appeared to migrate via the circulatory system and by direct penetration of tissues and organs. Patent infections were not found in three domestic goats (Capra hircus) up to 101 days after exposure to 300 or 1000 third-stage larvae of P. odocoilei.
Seasonal changes in testicular histology of brown bullheads, Ictalurus nebulosus Lesueur
Authors: Burke M. G. , Leatherland J. F.
Published: December 2009

The seasonal changes in the cytology of the anterior spermatogenic testis permitted the reproductive cycle of Ictalurus nebulosus Lesueur to be divided into four periods: (i) a prespawning period (mid-April to June), associated with an increased gonadosomatic index (GSI), when the overwintering secondary spermatocytes matured into biflagellate spermatids and spermatozoa, and there was an increased vacuolation of Leydig and Sertoli cells; (ii) a spawning period (June to mid-July), associated with a fall in GSI, when Leydig cell vacuolation was maintained, Sertoli cell size and vacuolation became maximal, and spermatozoa were released; (iii) a postspawning period (mid-July to mid-August) characterized by an increase in spermatogenic activity and ending when the seminiferous tubules were filled with secondary spermatocytes; and (iv) a resting (overwintering) period (mid-August to mid-April) when the seminiferous tubules were filled with secondary spermatocytes; quiescent spermatogonia were evident in decreasing numbers and Sertoli and Leydig cells were small and apparently inactive until late in the period. The posterior glandular testis similarly exhibited seasonal changes in size and vacuolation with peak activity associated with the spawning period.
Seasonal changes in serum testosterone, 11-ketotestosterone, and 17β-estradiol levels in the brown bullhead, Ictalurus nebulosus Lesueur
Authors: Burke M. G. , Leatherland J. F. , Sumpter J. P.
Published: December 2009

The seasonal changes in gonadosomatic index (GSI) and serum testosterone, 11-ketotestosterone, and 17β-estradiol levels were measured in adult feral brown bullheads, Ictalurus nebulosus Lesueur. The maximum GSI of both male and female brown bullheads was considerably lower than that of most other teleostean species investigated. In males, the GSI began to increase in April concomitant with an increase in water temperature from 3 to 6 °C. The maximum GSI levels were evident throughout May and June (during the prespawning and spawning periods). Peaks of serum testosterone and serum 11-ketotestosterone levels were evident in mid-April and late May to June, and in mid-April and mid-May, respectively. In females there was a rapid increase in GSI during May, when the ambient water temperature reached 16 °C. The peak GSI was evident in mid- to late-May and had declined by early June. Peak serum testosterone and 11-ketotestosterone levels were evident in mid-April and again in late May, whereas peak 17β-estradiol levels were found in mid-May and mid-June. The peak serum testosterone levels in females were 4.5-fold higher than in the males, whereas the 11-ketotestosterone levels were similar in males and females.
Spatial organization of digestive processes in an adult carabid beetle, Scaphinotus marginatus (Coleoptera: Carabidae)
Authors: Cheeseman M. T. , Pritchard G.
Published: December 2009

Adults of Scaphinotus marginatus liquefy and lubricate food prior to ingestion by the application of a fluid containing trypsin and chymotrypsin. This fluid is unlikely to be a salivary secretion because carabids, like other coleopterans, lack well-developed salivary glands. Results indicate that the midgut secretes these enzymes but that they are stored in the crop from which they are regurgitated onto the food prior to feeding. After ingestion, food is stored and digested in the crop. The structure of a proventricular valve in relation to regurgitation and crop storage is discussed.
Disturbed ion balance in alevins of Atlantic salmon Salmo salar chronically exposed to sublethal concentrations of cadmium
Authors: Rombough Peter J. , Garside E. T.
Published: December 2009

Embryos and alevins of Atlantic salmon Salmo salar were exposed to cadmium concentrations ranging from 0.47 to 300 μg Cd/L from shortly after fertilization to near complete yolk absorption (92 days). Tissue sodium, potassium, calcium, magnesium, and water contents of embryos and alevins were determined at 9-day intervals during this period. Cadmium had no significant effect on the tissue cation or water contents of embryos. Net water uptake by alevins was significantly inhibited at cadmium concentrations ≥0.78 μg Cd/L. Net sodium uptake was significantly inhibited at all concentrations except 79 and 300 μg Cd/L, but because of the concomitant decrease in water uptake there were no significant changes in sodium to water ratios. Net potassium uptake was significantly inhibited at concentrations ≥ 8.2 μg Cd/L and net calcium uptake was significantly inhibited at concentrations ≥ 0.78 μg Cd/L. Tissue magnesium was not affected. Calcification of skeletal elements was inhibited progressively at concentrations ≥ 0.78 μg Cd/L. Low tissue potassium and calcium levels appeared to be responsible for many of the symptoms associated with cadmium poisoning and were probably the immediate cause of death.