bluuebunny/crossref_metadata_2025 huggingface dataset:
Ratios in Aquatic Sciences: Statistical Shortcomings with Mean Depth and the Morphoedaphic Index
Authors: Jackson Donald A. , Harvey Harold H. , Somers Keith M.
Published: August 2008

Researchers in aquatic sciences frequently employ empirically derived models to predict productivity, yield, and abundance of fish. We demonstrate that predictive models employing ratios of standardized biomass and lake morphometric variables are biased by spurious correlations due to mathematical transformations and the use of inappropriate null models. Our findings emphasise that studies incorporating ratios like mean depth or the morphoedaphic index require cautious interpretation. Future research should focus on more appropriate analytical approaches such as regression-based models like the analysis of covariance. Alternatively, where ratios are employed and spurious correlations are likely, statistical evaluations must incorporate randomization tests to assess the significance of such results.
Reproductive Homing in Muskellunge, Esox masquinongy
Authors: Crossman E. J.
Published: August 2008

The number and nature of muskellunge moving to and from spawning grounds are extensively documented. Individual spawning muskeliunge in Stony Lake, Ontario are considered to home annually to specific spawning grounds and to specific areas (spawning sites) within spawning grounds. Some individuals were caught in the same location, or a nearby location, in as many as 7 yr. There is some evidence for discrete populations with apparent reproductive isolation and no interchange in summer. Dispersal from spawning grounds to summer home ranges seems to be limited in regard to direction and area of the lake. Recapture of fish on spawning grounds suggests an obligatory return to a limited number of "traditional" spawning grounds and may extend our knowledge of the groups of fishes exhibiting this type of directed movement. The results also have serious implications for muskellunge in regard to management, shoreline development, and genetic contamination by fish culture activities.
Fixed-Location Hydroacoustic Monitoring Designs for Estimating Fish Passage Using Stratified Random and Systematic Sampling
Authors: Skalski John R. , Hoffmann Annette , Ransom Bruce H. , Steig Tracey W.
Published: August 2008

Five alternative finite sampling designs are compared using 15 d of 24-h continuous hydroacoustic data to identify the most favorable approach to fixed-location hydroacoustic monitoring of salmonid outmigrants. Four alternative approaches to systematic sampling are compared among themselves and with stratified random sampling (STRS). Stratifying systematic sampling (STSYS) on a daily basis is found to reduce sampling error in multiday monitoring studies. Although sampling precision was predictable with varying levels of effort in STRS, neither magnitude nor direction of change in precision was predictable when effort was varied in systematic sampling (SYS). Furthermore, modifying systematic sampling to include replicated (e.g., nested) sampling (RSYS) is further shown to provide unbiased point and variance estimates as does STRS. Numerous short sampling intervals (e.g., 12 samples of 1 -min duration per hour) must be monitored hourly using RSYS to provide efficient, unbiased point and interval estimates. For equal levels of effort, STRS outperformed all variations of SYS examined. Parametric approaches to confidence interval estimates are found to be superior to nonparametric interval estimates (i.e., bootstrap and jackknife) in estimating total fish passage.
Using Hard-part Increment Data to Estimate Age and Environmental Effects
Authors: Weisberg Sanford
Published: August 2008

Fish grow in response to the extrinsic effects of their biotic and abiotic environment and in accordance with the intrinsic effects of size or age already attained. In this paper, a family of linear models are proposed that assume that growth, as reflected in increments in scales or other bony structures, can be divided into intrinsic age or size effects and external environmental effects. The models presented are of varying complexity. Some of the models use data from annular rings on bony parts, some use length or size attained, and some use both. Generalization to nonlinear or generalized linear models is indicated. Methodology for comparing subsamples of fish, based on sex, condition, trapping method, or any other identifiable characteristic, is discussed. The models are applied to several samples of smallmouth bass (Micropterus dolomieu) collected during 1988–90.
Relationship of Salmonine Production to Lake Trophic Status and Temperature
Authors: Plante Céline , Downing John A.
Published: August 2008

Data on trout, char, and salmon from lakes in several geographic areas indicate that salmonine production (P, kilograms per hectare per year) increases with total phosphorus concentration (TP, micrograms per litre) as log10P = 0.47 + 0.95 log10TP (r2 = 0.61). A positive relationship was also found between P and phytoplankton productivity and this relationship suggests that energy transfer efficiencies from phytoplankton to salmonines are reduced in eutrophic lakes. Lake area and mean depth had no significant statistical effect on P but salmonine production was significantly lower in warmer climates. Analysis of these data suggests that projected global increases in air temperatures could lead to about 50% reductions in salmonine production and yield in the north temperate zone.
Probing DNA polymerase activity with stereoisomeric 2′-fluoro-β-D-arabinose (2′F-araNTPs) and 2′-fluoro-β-D-ribose (2′F-rNTPs) nucleoside 5′-triphosphates
Authors: Peng Chang G , Damha Masad J
Published: August 2008

2′-Deoxy-2′-fluoro-β-D-ribonucleosides (2′F-rN) and 2′-deoxy-2′-fluoro-β-D-arabinonucleosides (2′F-araN) differ solely in the stereochemistry at the 2′-carbon of the furanose sugar ring. 2′F-rN 5′-triphosphates (2′F-rNTPs) are among the most commonly used sugar-modified nucleoside 5′-triphosphates (NTPs) for in vitro selection; however, the epimeric 2′F-araN 5′-triphosphates (2′F-araNTPs) have only recently been applied to polymerase-directed biosynthesis [C.G. Peng and M.J. Damha. J. Am. Chem. Soc. 129, 5310 (2007)]. The present study describes primer extension assays that compare, for the first time, the incorporation efficiency of the two isomeric NTPs, namely, 2′F-araNTPs or 2′F-rNTPs, by four DNA polymerases [Deep Vent (exo-), 9°Nm, HIV-1 RT, and MMLV-RT]. Under the conditions used, incorporation of 2′F-araTTP proceeded more efficiently relative to 2′F-rUTP, while the incorporation of 2′F-araCTP is comparable or slightly less efficient than that observed with 2′F-rCTP. Interestingly, these preferences were observed for all four of the DNA polymerases tested. Unexpected differences in NTP incorporation were observed for 2′F-rCTP vs. rCTP. Despite their seemingly similar conformation, they behaved striking differently in the in vitro polymerization assays. 2′F-rCTP is a much better substrate than the native counterpart (rCTP), an observation first made with human DNA polymerases [F.C. Richardson, R.D. Kuchta, A. Mazurkiewicz, K.A. Richardson. Biochem. Pharmacol. 59, 1045 (2000)]. In contrast, 2′F-rUTP behaved like rUTP, providing poor yield of full-length products. Taken together, this indicates that 2′F-rCTP is very unusual with regard to enzyme/substrate recognition; an observation that can be exploited for the production of DNA oligomers enriched with both ribose and arabinose modifications. These findings are timely given the significant interest and growing need to develop chemically modified oligonucleotides for therapeutic and diagnostic research. By examining the structure-activity relationship (SAR) of the ribose and arabinose sugar, this study furthers our understanding of how the nature of the 2′ substituent (e.g., α vs. β; F vs. OH) and the heterocyclic base affect NTP selection (specificity) by DNA polymerases.Key words: 2′F-rNTPs, 2′F-araNTPs, DNA polymerases, biosynthesis, modified nucleoside triphosphates.
First-order parallel and consecutive reaction mechanisms — Isosbestic points criterium
Authors: Croce A E
Published: August 2008

A criterium for the selection of reaction mechanism derived from a condition for isosbestic points occurrence is presented. Analytical relationships involving the molar absorption coefficients of the species, which participate in a mechanism of parallel first-order reactions and the corresponding rate coefficients, are also reported. A model system of four species that present overlapping absorption spectra may correspond to the reactant and products of a system of parallel or consecutive first-order reactions. In the first case, under experimental conditions in which the absorbances are additive, the presence of an isosbestic point in the spectrum of the reaction mixture at a given wavelength leads to a time-independent ratio of the degree of advancement of reaction variables. From this, relevant kinetic information may be extracted, namely, the ratio of the reaction rate coefficients. Moreover, the occurrence of isosbestic points allows discarding the second mechanism. This conclusion is independent of the number of absorbing species. Model calculated examples show the application of the equations here derived. The resolution for the general case of mechanisms of N first-order reactions is provided.Key words: chemical kinetics, time-resolved absorption spectra, reaction mechanism.
Description de nymphes d'Elmidae néarctiques (Coléoptères)
Authors: LeSage Laurent , Harper P. P.
Published: August 2008

Pupae of five species of Elmidae are described: Oulimnius latiusculus, Stenelmis crenata, Macronychus glabratus, Promoresia tardella, and Optioservus ampliatus. Pupae of the genera Promoresia and Optioservus were hitherto unknown. Observations on the ecology of these species are also presented.
Observations on the sporogony of Plasmodium circumflexum Kikuth and Plasmodium polare Manwell in New Brunswick
Authors: Meyer Clinton L. , Bennett Gordon F.
Published: August 2008

The sporogony of Plasmodium circumflexum in Culiseta morsitans is described. Sporozoites were first noted in the salivary glands on the 8th postinfective day; oocysts were still maturing on the 16th postinfective day. Culiseta morsitans was considered to be a good functional vector of Plasmodium circumflexum and the probable natural vector of this parasite in the Tantramar Marshes of New Brunswick. Plasmodium circumflexum did not show sporogonic development in 10 other culicines of three genera obtained in the same area but did complete sporogony in Mansonia perturbans. Plasmodium polare also completed sporogony in Culiseta morsitans and Mansonia perturbans but did not develop in other culicids. A review of the known potential of members of the genus Culiseta as vectors of avian Plasmodium indicates that this genus has previously been underrated and that it shows the greatest potential of all the culicid genera.
Histological changes in the ovary in relation to yolk deposition, allatectomy, and destruction of the median neurosecretory cells in Melanoplus sanguinipes
Authors: Elliott R. H. , Gillott C.
Published: August 2008

Histological changes in the ovary during periods of yolk deposition suggest that differentiation of the follicular epithelium and oolemma is an essential prerequisite to the pinocytotic uptake of protein into the oocytes. Before vitellogenesis, intercellular spaces form between adjacent follicle cells, and a brush border appears along the oocyte surface. The presence of protein within these spaces and of elementary yolk spheres along the brush border suggests that protein reaches the oocyte by an intercellular route.Accumulation of yolk does not occur after allatectomy or median neurosecretory cell (mNSC) cautery. Allatectomy inhibits the differentiation of the follicle cells and oolemma. In contrast, after mNSC cautery, differentiation occurs but the pinocytotic vesicles pinched off from the oolemma are empty, indicating that the availability of yolk precursors, not the uptake mechanism, has been affected. In addition, the appearance of secretion in the lateral oviducts is prevented by allatectomy, but merely delayed by mNSC cautery. The findings indicate that the corpora allata, but not the mNSC, are the source of a gonadotropin that regulates follicle-cell differentiation and the development of secretion in the lateral oviducts.
Effects of three pesticides on respiration, coughing, and heart rates of rainbow trout (Salmo gairdneri Richardson)
Authors: Lunn Carolyn R. , Toews Daniel P. , Pree David J.
Published: August 2008

Short-term, sublethal changes in respiration, heart, and coughing rates in juvenile rainbow trout (1–1.5 years) exposed to the organochlorine pesticides p,p′-DDT (1,1,1-trichloro-2,2-bis(p-chlorophenyl)ethane) and HEOD (dieldrin) and the methyl carbamate insecticide carbaryl (1-naphthyl N-methyl carbamate) were monitored at 13 ± 2 °C to investigate the effects of these pesticides on fish in fresh water. Sublethal responses to carbaryl and HEOD on physiological parameters were difficult to measure because dosages required to elicit them resulted in 30% to 60% mortality. DDT in various concentrations gave graded sublethal responses, and it is suggested that the coughing response in particular might be useful as a water-quality index. The DDT threshold for the coughing response was between 52 and 140 parts per billion.
Effects of temperature and sex genotype on meristic counts of the gonochoristic cyprinodontid fish Rivulus cylindraceus Poey
Authors: Harrington Jr. R. W. , Crossman Jr. R. A.
Published: August 2008

Eggs were reared at sustained temperatures of 19 °C, 25 °C, and 31 °C, Thermal response curves were declivous (vertebrae), aclivous(caudal and anal fin rays),of inverted-V shape {pectoral and dorsal rays), and nondescript (pelvic rays). Thermally induced vertebral differences in Rivulus cylindraceus, as in previously studied gonochoristic fishes, were far smaller than in a homozygous clone (uniparental, isogenic line) of selfing, hermaphroditic R. marmoratus Poey. Mean counts of males were higher for all meristic trails at 19 °C and for vertebrae and rays of pectoral and caudal fins at all three temperatures, those of females were higher for dorsal, anal, and pelvic fins at 25 °C and 31 °C. Differences in means between sexes were significant statistically for pectoral and anal rays at 19 °C, pectoral rays at 25 °C, and dorsal rays at 31 °C. Among three genetically different homozygous clones of R. marmoratus, mean meristic counts were neither significantly different nor consistently higher between males and hermaphrodites. The switch mechanism determining 'sex type' (male versus hermaphrodite) in homogametic R. marmoratus is thermal, and meristic variability is thermally influenced. Meristic variability in heterogametic R. cylindraceus is also thermally influenced but the switch mechanism determining sex is chromosomal, with apparent side effects on meristic counts.
Environmental control of univoltinism and its evolution in an insect species
Authors: Tauber Maurice J. , Tauber Catherine A.
Published: August 2008

Chrysopa downesi, a conifer-inhabiting unicyclic insect species, shares many features in its seasonal cycle with some well-studied single-brooded birds: a quantitative response to winter daylengths, reproduction in early spring, a summer 'photorefractory' phase, and a short-day requirement for termination of this phase. Under natural conditions, C. downesi has an aestival–autumnal–hibernal reproductive diapause that is primarily controlled by photoperiod. The short-day requirement for diapause termination is fulfilled in October. Subsequently, during winter, the rate of diapause development is directly related to the actual duration of daylength, and diapause ends between March 1 and March 21. Oviposition begins in mid-April. The rate of egg and larval development is primarily regulated by temperature; the lower thermal threshold for development (t) is 11 °C, and K value (heat-degree days) for the period from egg to adult emergence is 378 day °C.The late ending of C. downesi's diapause, its relatively high t value, and its aestival diapause separate temporally the reproductive periods of this species and its sympatric sibling species, Chrysopa carnea. The asynchronous seasonal cycles of C. downesi and C. carnea form a major barrier to hybridization between natural populations of the two species in the northeastern United States.
Periodicity of hibernation of dormice (Glis glis) maintained under controlled conditions
Authors: Scott Grace Workman , Fisher Kenneth C.
Published: August 2008

The pattern of hibernation of nine captive dormice Glis glis kept at 0 °C and 12 h light: 12 h dark for several years was determined. Six of the animals hibernated deeply. In these the separation between an active and a hibernation season was less distinct than in species previously studied and this led to difficulties in measuring the period of the hibernation cycle. These were resolved by the use of a monthly hibernation index, used here for the first time. In five of the animals, on one or more occasions hibernation continued without arousal for more than 25 days; the maximum uninterrupted period of hibernation was 40 days. The observations made were consistent with the view that hibernation in Glis glis results from an endogenous rhythm. However, the period of the rhythm, only 6.1 months on the average, was not circannual.
Distribution, abundance, size, and genetic variation of Peromyscus maniculatus on the Gulf Islands of British Columbia
Authors: Redfield J. A.
Published: August 2008

On the Gulf Islands, Peromyscus maniculatus is found only on islands larger than 25 hectares (ha). Mandarte (5 ha) was an exception to this pattern but 15 other islands less than 25 ha had no deer mice. Tumbo (121 ha) was the only island larger than 25 ha without deer mice. Deer mice were abundant on the occupied islands and nearly all mice were adults in breeding condition. The average body weight of island mice was higher than for mainland deer mice.Genetic variation at the transferrin locus in P. maniculatus has also been examined. TfJ, the most common allele, had an average frequency of 0.74 on the islands, the same as the frequency of TfJ on the mainland. The variance of allele frequency was the same in mice on large and small islands. Physical proximity of islands was not related to allele frequency. Indeed, islands connected at low tide by sand beaches had widely different allele frequencies, and in one case a different set of alleles. These data quite clearly suggest a lack of genetic exchange between islands, even islands so close as to be connected at low tide. Little contemporary colonisation by P. maniculatus is evident. Extinction without subsequent colonisation appears to be the rule on these islands. The deer mice on these islands are not in a state of dynamic equilibrium.Dans les îles du Golfe, en Colombie Britannique, on rencontre des Peromyscus maniculatus seulement dans les îles pi us grandes que 25 hectares (ha), Mandarte (5 ha) constitue l'exception. mais 15 autres îles plus petites que 25 ha sont dépourvues de campagnols, Tumbo (121 ha) est la seule île plus grande que 25 ha à être dépourvue de campagnols. Dans les îles occupées, les campagnols sont présents en abondance et presque tous sont des adultes en état de reproductïon. Le poids moyen des campagnols insulaires est pins grand que celui des campagnols habitant le continent.
Opportunistic feeding by desert bats (Myotis spp.)
Authors: Fenton M. B. , Morris G. K.
Published: August 2008

By using a 'black light' and playback of sounds made by foraging insectivorous bats, we examined opportunistic feeding behavior of bats near Camp Verde, Arizona, between 1 and 10 June 1975. Bats were significantly most active during 15-min periods when the light was on and insects were aggregated over it. Bats feeding over the light selectively pursued and captured larger insects, apparently ignoring the smaller ones. Bats did not respond to sounds simulating feeding buzzes of bats, but showed a slight response to the foraging sounds of other bats. Opportunistic feeding by insectivorous bats allows effective exploitation of patchily distributed food resources and can lead to selective feeding when 'hatches' of insects are involved. Opportunistic feeding is not incompatible with selective feeding, and may eventually be established as a strategy common to most insectivorous bats.
The effect of porcine somatotropin on growth, and survival in seawater of Atlantic salmon (Salmo salar) parr
Authors: Komourdjian M. P. , Saunders R. L. , Fenwick J. C.
Published: August 2008

The effects of porcine growth hormone on growth and salinity tolerance were studied in Atlantic salmon (Salmo salar) parr. Fish were held in freshwater at 11.5 °C during June and July under a photoperiod with light to dark periods opposite to the prevailing natural conditions. Fish treated with 1.0 μg/g body weight of growth hormone preparation on alternate days were significantly longer (P <.05), after 4 weeks, than placebo-injected controls. All hormone-injected fish survived transfer to seawater, 30‰ salinity. But under the same conditions, placebo-injected control fish showed a high mortality rate. Growth-hormone treatment caused a darkening of fin margins and a yellowing of the operculae and fin surfaces. The silvering which normally accompanies smoltification was not observed. The role of growth hormone in eliciting these actions and its possible role in the parr–smolt transformation are discussed.
Effects of thermal effluents on the population dynamics of Physa gyrina Say (Mollusca: Gastropoda) at Lake Wabamun, Alberta
Authors: Sankurathri Chandra S. , Holmes John C.
Published: August 2008

Effects of thermal effluents on the population dynamics of Physa gyrina Say (Gastropoda: Pulmonata) were studied at Lake Wabamun, Alberta, from May 1971 to August 1973. Thermal effluent increased the rate of development of eggs and the growth of P. gyrina, and allowed continuous reproductive activity throughout the year. These changes, and the increased period of growth of aquatic macrophytes, resulted in increased population densities of P. gyrina in the heated area during summer. Temperatures below 10 °C or small amounts of vegetation appear to limit the population of P. gyrina in winter.
A new organ in cestode surface ultrastructure
Authors: Boyce Norbert P.
Published: August 2008

Certain organs discovered among the microtriches on the surface of Eubothrium salvelini (Cestoda: Pseudophyllidea) are described. These organs, designated 'tumuli,' occur on at least two other representatives of the order Pseudophyllidea.
A laboratory simulation of predator-induced incubation interruption using ring-billed gull eggs
Authors: Hunter R. A. , Ross H. A. , Ball A. J. S.
Published: August 2008

Field observations have shown that nocturnal predation may cause nest desertion by adult larids. Such desertion was simulated by exposing laboratory-incubated ring-billed gull eggs to 10 °C at either early, intermediate, or late periods of incubation. Hatchability was not significantly reduced by exposure. However, when eggs classed as 'non-viable at collection time' were eliminated, an increase in embryonic mortality was found to occur in late samples. The mean incubation time of all experimental eggs was slightly increased and the variance of incubation time was significantly greater for groups of eggs that suffered longer exposures at middle and late points in incubation. It is suggested that predator-induced desertion in natural populations may increase embryonic mortality and chick age heterogeneity, which in turn may reduce chick survival.
Stream habitat selection by aerially colonizing invertebrates
Authors: Williams D. Dudley , Hynes H. B. N.
Published: August 2008

Experiments on site selection by aerially colonizing invertebrates showed that water current and food availability largely determine the qualitative and quantitative nature of the fauna that colonizes a body. New water bodies were rapidly colonized by a variety of species from nearby lotic and lentic habitats. After some time selection took place to establish communities characteristic of the habitats.
Pathophysiology and compensatory mechanisms in a compatible host–parasite system
Authors: Podesta R. B. , Mettrick D. F.
Published: August 2008

The effect of intraluminal glucose and bicarbonate on the fluxes of Na+, Cl−, and water were investigated in both infected (Hymenolepis diminuta: Cestoda) and uninfected rats.In the parasitized small intestine, the glucose-stimulated component of salt and water absorption was accelerated, and bicarbonate-stimulated Na+ and fluid absorption was enhanced by being spread over a larger region.The results are discussed in terms of the possible protective effects of an abnormally low mucosal permeability, the accelerated glucose-stimulated fluid absorption, the spreading of bicarbonate-stimulated fluid absorption over a larger region of the gut, and functional compensation by the colon. These protective alternatives in mucosal function explain how the parasitized rat gut compensates for the loss of fluid caused by defects in other transport processes, even though considerable maldigestion and malabsorption occurs.
Littoral Rotifera of Ontario—the genus Lepadella Bory de St. Vincent
Authors: Chengalath R.
Published: August 2008

In this, the third paper on the littoral Rotifera of Ontario, 12 species belonging to the genus Lepadella, including some rare species, are presented. Short descriptions, measurements, and detailed drawings, showing variation, where necessary, are given. Of the 12 species reported, 8 are new records for Canada.
Ultrastructure and functional morphology of spermatozoa of Rossia pacifica (Cephalopoda, Decapoda)
Authors: Fields W. Gordon , Thompson Kathleen A.
Published: August 2008

The mature spermatozoan of Rossia pacifica consists of acrosome, nucleus, mitochondrial spur, and tail. Anteriorly, the complex acrosome has a cup-shaped depression containing membrane-bound vacuoles. The acrosome is enclosed by a meshwork of longitudinal and circumferential filaments; its invaginated posterior end surrounds juxtanuclear periacrosomal material. The elongated nucleus, of condensed chromatin filaments, encloses lateroposteriorly the proximal and distal centrioles within a centriolar fossa. Mitochondria lie in a separate, spurlike appendage; proximally its lateral margins are continuous with a collarlike annulus. Nine coarse outer fibres surround the 9 + 2 axoneme. They originate from a centriolar ring and diminish in diameter distally. Staining with periodic acid – Schiff demonstrates some glycogen in the mitochondrial spur near its junction with the nucleus.Structural significance and possible functional roles of the various elements are discussed relevant to fertilization. Although this sperm appears intermediate between the more primitive invertebrate sperm type and highly specialized vertebrate sperm, its morphology seems more related to fertilization biology than to phylogenetic position. The singular separateness of areas of energy production and use in R. pacifica sperm and the lengthy energy-transport path may provide unique opportunities for analysis of metabolic processes common to but indecipherable in other sperm.
A second nonparasitic species of Entosphenus Gill, 1862 (Petromyzonidae) from Klamath River System, California
Authors: Vladykov Vadim D. , Kott Edward
Published: August 2008

A new nonparasitic lamprey, Entosphenus folletti from the Klamath River system, California, is described and illustrated. The holotype (No. NMC 75-1549) is deposited in the National Museum of Natural Sciences, Ottawa, Canada. The species, by its non-functional intestinal tract, is easily separable from the two parasitic species: E. tridentatus and E. minimus. It differs from the nonparasitic E. lethophagus, of the same river system, by having (1) a larger disc: 6.6–7.8% of total length (4.1–6.1% in E. lethophagus), (2) a stronger dentition and a higher number of inner lateral cusps: 2-3-3-2 against 2-2-2-2, (3) a median velar tentacle that is well developed and the same size as the lateral, while in E. lethophagus it is greatly reduced in size in comparison with lateral tentacles, and (4) a darker body coloration and heavily pigmented second dorsal fin. In ammocoetes of E. folletti the bulb of the tongue precursor has a dark pigmentation that is absent in E. lethophagus. The description is based on a study of six transformed individuals and 25 ammocoetes.
The microanatomy of the optic ganglia of Munida irrasa (Decapoda: Galatheidae)
Authors: Bursey Charles R.
Published: August 2008

The microanatomy of the optic ganglia of Munida irrasa was examined by reconstruction from stained serial sections. There are four optic ganglia arranged in a consecutive manner: a distal lamina ganglionaris followed by a medulla externis, medulla internis, and medulla terminalis. Two optic chiasmata are present. Typically, the major constituents of invertebrate ganglia are present: rind, neuropil, blood sinuses, hemocytes, and glia.Neurosecretory cells are found within each of the four ganglia. They are arranged at regular intervals throughout the proximal zone of the lamina ganglionaris. They are collected into ganglionic X organs in the other three ganglia. The medulla externis X organ sends its fiber tract into the lamina ganglionaris. The medulla internis X organ and the medulla terminalis X organ send their combined fiber tract into the sinus gland.The sinus gland is the only peripheral structure to receive axons from cells of the optic ganglia. The organ of Bellonci is wholly contained within the medulla terminalis. A cavity receptor organ is present in the periphery of the eyestalk; however, its nerve parallels the optic ganglia and enters the brain directly.
Sexual selection in toads (Bufo americanus)
Authors: Licht Lawrence E.
Published: August 2008

The breeding behavior of the American toad, Bufo americanus, in southern Ontario, is described. The hypothesis is presented that the male vocalization, that call normally given by mature males at the spawning site, can function, not only as a premating isolating mechanism, but as a means for sexual selection by breeding toads. Descriptive and experimental evidence is given to support the hypothesis.
Can tongue flicks be used to measure niche sizes?
Authors: Carr Catherine M. , Gregory Patrick T.
Published: August 2008

Competition between animal species is often inferred from a demonstration of niche 'shift' in one or both species. In snakes, potential niches along the food-type dimension may be measurable in terms of responses of naive young snakes to chemical stimuli of various prey types. If responses differ markedly from actual food habits in the wild, diet shift due to competition may be implied. This approach was used on naive young of three species of garter snakes (Thamnophis) that coexist on Vancouver Island. Responses to stimuli, measured as numbers of tongue flicks per minute, were generally strong to prey normally eaten in the field, but strong responses to unusual prey items were also noted. No two species responded identically to all the stimuli used. The diets of two of the species are possibly determined in part by competition between them. Various weaknesses of this method and other interpretations of results are discussed.
The regulation of day–night changes in hydroxyindole-O-methyltransferase activity in the pineal gland of steelhead trout (Salmo gairdneri)
Authors: Smith John R. , Weber Lavern J.
Published: August 2008

Elevation in pineal hydroxyindole-O-methyltransferase (HIOMT; EC 2.1.1.4) activity in juvenile steelhead trout was associated with the dark portions of three different photoperiods with a sharp increase in pineal HIOMT activity occurring in the first 4 h of darkness. This pattern of activity could be abolished by bilateral enucleation but not by surgical capping of the pineal region. Surgical exposure of the pineal region in blinded fish did not restore HIOMT responses to changes in lighting.
Seasonal and diel changes in the positioning of Glossosoma nigrior Banks (Trichoptera: Glossosomatidae) on artificial substrates
Authors: Kovalak William P.
Published: August 2008

Seasonal and diel changes in the positioning of larvae of Glossosoma nigrior on bricks are described. Between July and November the proportion on the top face increased, the proportion on the front (upstream) face decreased, and the proportion on other faces remained relatively unchanged. These changes were related to seasonal changes in water temperature. The positioning of larvae was dependent on current velocity only at higher water temperatures (> 19 °C). At lower current velocities (< 70 cm/s) larvae were predominantly on the front, whereas at higher current velocities they were more equally distributed on the top, front, and sides. Diel changes in positioning were apparent only at higher water temperatures (> 19 °C) and were characterized by an increase in the proportion on the front and decrease in the proportion on the top at night. Diel changes in positioning were not related to phototactic responses. G. nigrior appeared to use positioning to help satisfy respiratory requirements. At high water temperatures and at low current velocities the largest proportion were on the front where oxygen richness was greatest. It was hypothesized that nocturnal increases in the proportion on the front were controlled by diel rhythms of oxygen-consumption rate.
Hormonal regulation of reproduction and the antler cycle in the male Columbian black-tailed deer (Odocoileus hemionus columbianus). Part II. The effects of methallibure and hormone treatment
Authors: West Nels O. , Nordan H. C.
Published: August 2008

Methallibure, a non-steroidal inhibitor of gonadotrophin secretion, arrested antler growth and suppressed reproduction. The administration of prolactin, pregnant mares' serum gonadotrophin (PMS), and some androgenic steroids to methallibure-treated deer during June and July failed to stimulate antler growth, but human chorionic gonadotrophin (HCG) did rejuvenate it in one instance. None of these hormones was effective in completely restoring reproductive function, although PMS and HCG were capable of stimulating the production of enough testosterone to induce velvet shedding.During the normal period of antler growth, the testes of methallibure-treated deer did not respond to the exogenous administration of HCG by secreting testosterone, whereas both PMS and prolactin were effective in this respect. After the administration of PMS, HCG was capable of stimulating testosterone production, but it was ineffective in the deer previously treated with prolactin. Also, when methallibure treatment was terminated in the fall, testosterone production and spermatogenesis recovered, but the deer that had previously received prolactin did not produce mature sperm until the next spring. Thus, the testicular response may depend on the temporal sequence as well as on the type of hormonal stimulation. The results of this study support the hypothesis that a gonadotrophin is responsible for stimulating antler growth.
Aquatic mollusks in North Dakota during the last 12000 years
Authors: Cvancara A. M.
Published: August 2008

Aquatic mollusks occurred in North Dakota during the last 12 000 years as follows: 12 000–10 000 years ago, 19 species (dated material from 3 sites); 10 000–8000 years ago, 22 species (dated material from 5 sites); 8000–4000 years ago, 11 species (material of inferred age from 2 sites); 4000 years ago to present, 36 species (dated material from 1 site and material of inferred age from 23 sites); and present day, 44 species (material from about 300 stations). The gastropods Valvata sincera (Say), Fossaria decampi (Streng), and Helisoma campanulatum (Say) have not been found in sediments younger than about 9600 years. They may have become regionally extinct about 9000 years ago because of a warmer, drier climate and a corresponding increase of dissolved salts in surface waters. Of two hydrobiid gastropods, Amnicola limosa (Say) has not been found in sediments younger than about 9000 years and has been found at relatively few localities today. Cincinnatia cincinnatiensis (Anthony) has not been found in sediments older than about 2500 years and has been found at many localities today. The occurrence of these two species with time may also be the result of changing climate and surface-water chemistry.
Effects of thermal effluents on parasites and commensals of Physa gyrina Say (Mollusca: Gastropoda) and their interactions at Lake Wabamun, Alberta
Authors: Sankurathri Chandra S. , Holmes John C.
Published: August 2008

Effects of thermal effluents on the dynamics of larval helminth parasites and on populations of Chaetogaster limnaei limnaei and Chaetogaster limnaei vaghini (Annelida: Oligochaeta) harbored by Physa gyrina (Mollusca: Pulmonata) were studied at Lake Wabamun, Alberta. Thermal effluents provided the necessary conditions to maintain digenean parasite transmission throughout the year between definitive and intermediate hosts, and increased the prevalence of certain parasites, especially the metacercarial stages.At temperatures above 24 °C prevalences of C. l. limnaei and C. l. vaghini decreased in the lake, and at these temperatures in the laboratory C. l. limnaei abondoned the snails and perished. Under experimental conditions the number of Echinoparyphium recurvatum larvae penetrated Physa gyrina was inversely related to the number of C. l. limnaei present. It was also observed that these oligochaetes actively ingested digenean larvae. Elimination of C. l. limnaei caused by thermal effluents has augmented the metacercarial infections.An ecological model depicting the interactions of Physa gyrina – digeneans – Chaetogaster l. limnaei is presented. This is a complex system in which water temperature acts as a main regulating factor. The three main components of the system interact with each other and are influenced by various external factors, resulting in a dynamic ecological system.
Neurosecretion and shell regeneration in Helisoma duryi (Mollusca: Pulmonata)
Authors: Dillaman R. M. , Saleuddin A. S. M. , Jones Gwyneth M.
Published: August 2008

The distribution of cells that stain positively with paraldehyde fuchsin (PAF) in the brain of Helisoma duryi has been mapped. Two cell groups occur in the visceral ganglion, one of which (group 1) has been shown to contain electron-dense secretory granules resembling neurosecretory material. Backfilling experiments and serial sectioning show that group 1 cells send axons into the intestinal and left pallial nerves.PAF-positive material is depleted from group 1 cells between 24 and 48 h after shell removal and has reappeared by 72 h. PAF-positive material accumulates in the axons by 24 h and disappears by 48 h; shell regeneration is apparently complete within 15 days. Tissue injury alone or shell removal from a non-regenerating area does not cause depletion of stainable material in these cells. No change in stainability occurs in other PAF-positive cells in the brain during shell regeneration. It is suggested that this cycle of activity may indicate involvement of the group 1 neurosecretory cells in the control of shell regeneration.
A biochemical approach towards the taxonomy of leeches (Annelida: Hirudinea)
Authors: Khan R. A. , Cowan G. I. McT.
Published: August 2008

Whole specimens of starved marine leeches of two genera, were compared by means of micro starch-gel electrophoresis. Distinct electrophoretic banding patterns were observed between Malmiana scorpii and M. brunnea and Oceanobdella microstoma and O. sexoculata and corroborate previous identifications based on conventional taxonomic characteristics. The results indicate that this technique could be used for taxonomic separation of leeches at the specific and possibly at the generic level.
Fecundity and release of young in Diastylis sculpta Sars (Crustacea, Cumacea)
Authors: Corey Susan
Published: August 2008

Diastylis sculpta has two generations per year. The mean fecundity for the summer and overwintering females was 20.9 and 72.3 respectively. The marsupial larval stages increase in volume from 0.020 mm3, stage I, to 0.162 mm3, stage IV. The duration of release of the entire brood per female averaged 145 h (range 63–206 h). About 2% of the overwintering females produce a second brook.
Digestive processes of haematophagous insects. XI. Partial purification and some properties of six proteolytic enzymes from the tsetse fly Glossina morsitans morsitans Westwood (Diptera: Glossinidae)
Authors: Gooding R. H. , Rolseth B. M.
Published: August 2008

By O-(diethylaminoethyl)cellulose (DEAE-cellulose) chromatography, affinity chromatography, and Sephadex gel filtration, six proteolytic enzymes active in alkaline medium have been found in the digestive portion of the midgut (tissue and lumen contents) of adult Glossina morsitans morsitans. By use of synthetic substrates the enzymes have been characterized as aminopeptidase (AP; EC. 3.4.11.1), carboxypeptidase A (CPA; EC 3.4.12.2), carboxypeptidase B (CPB; EC 3.4.12.3), trypsin (EC 3.4.21.4), a trypsinlike enzyme designated proteinase VI, and a chymotrypsinlike enzyme designated proteinase VII. By Sephadex G-100 gel filtration the molecular weights were estimated to be 20 000 for trypsin, 19 000 for proteinase VI, 35 500 for proteinase VII, 30 000 for CPA, 22 000 for CPB, and [Formula: see text] for AP. The Km values (mg/ml) for haemoglobin were 3.43 for trypsin, 2.45 for proteinase VI, 3.68 for proteinase VII, and 2.42 for CPA. The Km values for casein were 1.22 for trypsin and 1.38 for proteinase VII. Casein showed substrate inhibition when hydrolyzed by proteinase VI and VII. Neither haemoglobin nor casein was hydrolyzed by AP and CPB. The pH optima were determined for hydrolysis of casein and the synthetic substrates.
Cytology of the anterior pituitary at different times of the year in normal and methallibure-treated male Columbian black-tailed deer (Odocoileus hemionus columbianus)
Authors: West Nels O. , Nordan H. C.
Published: August 2008

The application of histochemical staining techniques to the anterior pituitary revealed the presence of seven cell types. Most cell types underwent cyclic changes that could be related to a seasonal pattern of functional activity. The cell type tentatively identified as the interstitial-cell-stimulating hormone (ICSH) (luteinizing hormone) cell had the most pronounced seasonal cycle. Hormonal release by these cells, and other cells tentatively identified as follicle-stimulating hormone (FSH) cells, was judged to be greatest in the fall, but some activity was also apparent during the spring and summer. The somatotrophs appeared most active in spring and summer, whereas the lactotrophs appeared most active in the fall. With the possible exception of the corticotrophs, all the cells of the anterior pituitary showed the least signs of activity in late winter.The pituitaries of methallibure-treated deer sacrificed in July, November, and December contained ICSH cells and FSH cells that were small and chromophobic, whereas other cell types appeared to be affected little or not at all. This suggests that the main effect of methallibure on the anterior pituitary was to suppress the secretory activity of the gonadotrophic cells. The significance of these findings in relation to the hormonal regulation of reproduction and the antler cycle is discussed.
Morphological changes during the growth cycle of axenic and monoxenic Tetrahymena pyriformis
Authors: Taylor William D. , Gates Michael A. , Berger Jacques
Published: August 2008

Morphometric data were collected from Tetrahymena pyriformis (WH-14, syngen I, mating type II) grown in two different media, one axenic and one monoxenic (with Serratia marcescens), at various times during the growth cycle. Stationary phase cells differed morphometrically from exponential phase cells in different ways in the two media. It is proposed that, in the monoxenic medium, division stopped because the food resource was depleted, while in the axenic medium division was blocked before food limitation occurred.Cells in the two culture media showed consistent morphological differences during exponential phase, the axenic cells being larger (length and width), but having smaller (in length) mouths. Significant differences between cells in replicate experiments were frequently observed.
Scanning electron microscopic observations of the larval development of the reef-building polychaete Phragmatopoma lapidosa
Authors: Eckelbarger Kevin J. , Chia Fu-Shiang
Published: August 2008

The scanning electron microscope (SEM) was used in a study of the larval development of the reef-building sabellariid polychaete Phragmatopoma lapidosa. Mature sperm are modified from the 'primitive' polychaete plan by possessing a tapered and bent acrosome. The outer surface of the irregularly shaped, freshly spawned egg envelope is granular in appearance. SEM observations of various stages in development from the early trochophore through larval metamorphosis and the early juvenile stages suggest that the egg envelope serves as the cuticle through the trochophore stage but is then replaced by another cuticle penetrated by microvilli. SEM has revealed the presence of 'sensory tufts' on the dorsal surface of the larval tentacles which may play a role in larval substrate selection.
A review of the genus Actinobdella Moore, 1901 (Annelida, Hirudinea)
Authors: Daniels Bruce , Freeman R. S.
Published: August 2008

The genus Actinobdella Moore, 1901 is reviewed. Actinobdella inequiannulata Moore, 1901 is redescribed from specimens from Catostomus commersoni and Catostomus catostomus, collected at Algonquin Provincial Park, Ontario. Comparison with specimens from the United States National Museum indicates that Actinobdella triannulata Moore, 1924 is a junior synonym.
The influence of climatic factors on the demography of the terrestrial isopod Tracheoniscus rathkei Brandt
Authors: McQueen Donald J.
Published: August 2008

A field population of the isopod Tracheoniscus rathkei was monitored during 1971, 1972, and 1973. At the same time, laboratory data related to growth, reproduction, and survival were collected and combined to produce a simulation model. The model output was compared with the field data. In the laboratory, T. rathkei required humidities very near 100% relative humidity, day length had no effect on growth rates, and temperature altered rates of growth and survival and determined the periodicity of reproduction. In the field, T. rathkei exhibited a 2-year life cycle, breeding occurred in the spring and summer, and about 83% of the population bred once and 42% bred twice during each year. Juveniles grew throughout the fall, overwintered, reproduced at 1 year of age, continued to grow, overwintered a second time, reproduced again, and died. The simulation model mimicked this pattern with considerable precision. Both the field data and the simulated output suggested that the population expanded during 1971, 1972, and 1973. No mechanisms for population limitation were found.