bluuebunny/crossref_metadata_2025 huggingface dataset:
Life history, trophic behavior, and description of Gamasellodes vermivorax n. sp. (Mesostigmata: Ascidae), a predator of nematodes and arthropods in semiarid grassland soils
Authors: Walter David Evans
Published: March 2009

All life stages of Gamasellodes vermivorax n. sp. (Mesostigmata: Ascidae), a predator of mites, collembolans, and nematodes in semiarid grassland soils, are described. Female to female generation time is 10 days on a diet of rhabditid nematodes at 24 °C. Each adult female may produce one to three eggs daily for at least 2 weeks. Female deutonymphs are guarded by adult males. Isolated female deutonymphs molt to adults which begin laying eggs within 48 h of emergence. All eggs laid by unfertilized females develop into males, indicating a haplodiploid sex determination mechanism. In a microcosm experiment, nematode densities were negatively correlated with G. vermivorax densities.
Auditory recognition of covey mates from separation calls in Northern Bobwhite (Colinus virginianus)
Authors: Baker James A. , Bailey Edward D.
Published: March 2009

Two experiments were conducted to determine whether Northern Bobwhite (Colinus virginianus) discriminate covey mates from noncovey mates on the basis of recognition of the individual giving the separation call. Two possible modes of recognition, phenotype matching and call association, were tested. Artificially and naturally hatched quail chicks from two familial lines of linebred quail and quail of crossed lines were reared and tutored by either a related or an unrelated adult. Chicks were separated one at a time and visually isolated midway between their own adult tutor-parent and a strange adult or between their own covey and a strange covey in a two-choice recall paradigm for testing. In both linebred and crossed lines quail, chicks preferentially approached calls of the foster parent or covey mates with whom they were reared with no apparent predilection due to relatedness, with no regard for which birds answered the lost or separation call first, and with no dependency on similarity of call characteristics. All evidence indicated that association learning was the main factor in recognition with no evidence of kin recognition attributable to phenotype matching.
Biological aspects of Amazonian fishes. Hemoglobin, hematology, intraerythrocytic phosphates, and whole blood Bohr effect of Mylossoma duriventris
Authors: Monteiro Plínio José Cavalcante , Val Adalberto Luís , Almeida-Val Vera Maria Fonseca de
Published: March 2009

Hemoglobin, hematological parameters, intraerythrocytic phosphates, and whole blood Bohr effect of Mylossoma duriventris captured in the Amazon river were studied during five different periods of the year. Some important variations of these parameters are described and can be correlated to oxygen and water level oscillations. Four anodal hemoglobin fractions were detected on starch gel electrophoreses. ATP was the major intraerythrocytic phosphate during February, April, and August while GTP was the major phosphate during October and November. These two periods differ also in terms of water level and available oxygen. Whole blood Bohr effect is directly influenced by ATP and GTP concentrations.
Behavioral interactions differentiate Djungarian (Phodopus campbelli) and Siberian (Phodopus sungorus) hamsters
Authors: Wynne-Edwards Katherine E. , Lisk Robert D.
Published: March 2009

Male–male and female–female dyads of two species of Phodopus, the Djungarian hamster, P. campbelli, and the Siberian hamster, P. sungorus, interacted daily for 10 min on each of 4 successive days. Animals were acclimatized to large habitats which contained small, defensible nest boxes. Real time behavioral records were kept of agonistic, social, and scent marking behaviors. The results indicated that there were major behavioral differences between P. campbelli and P. sungorus in their agonistic interactions with like-sexed conspecifics. Male P. campbelli were significantly more aggressive towards conspecific males than male P. sungorus, attacking (19.7 ± 2.2 vs. 9.6 ± 1.2) and biting (30.0 ± 4.6 vs. 12.7 ± 2.1) more often, and could inflict serious injury. Conversely, female P. campbelli were less aggressive than female P. sungorus towards like-sexed conspecifics, attacking (2.6 ± 0.7 vs. 7.5 ± 1.5) and biting (1.0 ± 0.4 vs. 2.4 ± 0.6) less frequently. The absolute levels of aggression were higher for males than for females although the magnitude of the difference was much less in P. sungorus than in P. campbelli. Dominant animals showed a tendency to spend most of the time available in the home area of the subordinate animal and to scent mark more frequently while there. The time distributions of dominant and subordinate animals within pairs (except for P. sungorus males) were significantly positively correlated. Dominant animals of both sexes scent marked with similar frequencies. When interpreted in light of the literature concerning the possible social structure of Djungarian hamster populations, this study suggests that the differences between the two species are sufficiently large that it is important to carefully distinguish between them in the published record.
Functional morphology of the olfactory organ of two carcharhinid shark species
Authors: Zeiske Eckart , Theisen Birgit , Gruber Samuel H.
Published: March 2009

The paired olfactory organs of both the lemon shark (Negaprion brevirostris) and the silky shark (Carcharhinus falciformis) are located in solid cartilaginous nasal capsules, which open at the ventral side of the snout and are entirely separate from the mouth. The olfactory rosette consists of two rows of lamellae arising from a central raphe. The lamellae possess secondary folds covered with sensory epithelium, which contains microvillous receptor cells, supporting cells with both cilia and microvilli, basal cells, and goblet cells. No ciliated receptor cells were found. Gaps between facing lamellae connect the inlet chamber with the outlet chamber. The inlet chamber receives the ventilatory water through the incurrent nostril and the outlet chamber discharges the water through the excurrent nostril. A nasal flap, a septum, and paired valve flaps form an incomplete barrier between incurrent and excurrent nostrils and may have hydrodynamic functions, which are discussed.
The effects of altering gill water flow on gas transfer in rainbow trout
Authors: Iwama G. K. , Boutilier R. G. , Heming T. A. , Randall D. J. , Mazeaud M.
Published: March 2009

The relationship between gill ventilation and gas transfer was studied in rainbow trout. Gill ventilation volumes were experimentally manipulated and blood gases as well as oxygen and carbon dioxide transfer across the gill were measured. At ventilation volumes below about 100 mL/min, there was an increase in blood carbon dioxide and a decrease in blood oxygen tensions. Both oxygen and carbon dioxide transfer rates in this range also declined with ventilation volume. Ventilation volumes below this level, therefore, may limit gas exchange and change blood gas tensions given constant metabolic rates. Ventilation volumes greater than 100 mL/min had little effect on blood gas tensions.
Life cycle studies on two Digenea, Paradistomum geckonum (Dicrocoeliidae) and Mesocoelium sociale (Mesocoeliidae), in geckonid lizards from Indonesia
Authors: Kennedy Murray J. , Killick L. M. , Beverley-Burton M.
Published: March 2009

Life cycle studies of Paradistomum geckonum (Dicrocoeliidae) were attempted experimentally. The pulmonate gastropod Lamellaxis gracilis served as the first intermediate host; geckonid lizards (Cosymbotus platyurus, Gehyra mutilata, and Hemidactylus frenatus) served as definitive hosts. The life cycle of Mesocoelium sociale (Mesocoeliidae) was studied in naturally infected first intermediate hosts (L. gracilis, Huttonella bicolor) and experimentally in geckonid definitive hosts (C. platyurus, G. mutilata, and H. frenatus). Some naturally infected L. gracilis were infected concurrently with larval stages of both digeneans. Second intermediate hosts, presumed to be arthropods, were experimentally unnecessary. Metacercariae of P. geckonum were not found. Cercariae of M. sociale formed encysted metacercariae in the same individual snails.
Opiates and deer mouse behaviour: differences between island and mainland populations
Authors: Innes Duncan G. L. , Kavaliers Martin
Published: March 2009

A number of the behavioural and ecological characteristics of island populations of small mammals differ from their mainland counterparts. Little is known, however, about possible neurochemical correlates of these behavioural differences. Substantial evidence indicates that endogenous opioid peptides are differentially involved in the regulation of the expression of fundamental behavioural and physiological functions, including responses to aversive stimuli and enhanced nociceptive thresholds (analgesia). In the present study, we compared the effects of peripherally administered δ- κ-, and μ-opiate receptor directed agonists and antagonists on the analgesic responses and locomotor activity of four different populations of male and female deer mice: Peromyscus maniculatus artemisiae and P. m. nebrascensis from mainlands, and P. m. angustus and P. m. triangularis from small islands. The insular deer mice displayed markedly greater μ-opiate and significantly lower δ- and κ-opiate mediated responses than the mainland animals. In all of the populations males displayed significantly greater opiate-induced analgesic responses and locomotory changes than females. These results demonstrate that there are marked population and sex differences in the opiate-mediated behavioural responses of deer mice. These "pharmaco-ecological" findings also suggest that the behavioural differences between island and mainland populations of deer mice may, in part, be related to differences in opioid activity.
Onset of submaximal exercise in thoroughbred horses
Authors: Weber Jean-Michel , Parkhouse Wade S. , Dobson Geoffrey P. , Harman Joyce C. , Snow David H. , Hochachka Peter W.
Published: March 2009

Plasma lactate concentration, hematocrit, and heart rate were measured during a 40-min trot (3–4 m/s, 6% incline) and a 15-min canter (6.5 m/s, 0% incline) in catheterized thoroughbred horses running on a treadmill to characterize the transient changes in plasma lactate concentration during the onset of exercise, and to determine if and when a steady state was established. The intensity of exercise had an effect on the pattern of changes observed for the three variables investigated. Mean hematocrit rose from 38.5% at rest to 52.0% after a 4-min walk (1.6 m/s) and to 57.7% after 3 min of subsequent trotting (4 m/s). The highest mean value of 58.7% was reached after 3 min of cantering. A slow but significant decrease in hematocrit was measured between the time maximum levels were attained for each work intensity and the end of exercise. During the onset of submaximal work, plasma lactate concentration, hematocrit, and heart rate all reached a maximum simultaneously. The rapid cardiovascular response of thoroughbreds (strong hematocrit increase and heart-rate overshoot) did not prevent them from temporarily relying on anaerobic metabolism, as shown by a marked lactate overshoot before a steady state was established. The observed changes in lactate concentration are explained by a model predicting lactate fluxes to and from the plasma compartment during the transition from the resting steady state to the exercise steady state. Biopsies of the middle gluteal muscle were taken before and after the canter protocol to measure the metabolic intermediates of the glycogenolytic pathway. The resting and postexercise concentrations of these intermediates were not different except for a 30% reduction in glycogen. Aerobic glycogenolysis was the main pathway for energy metabolism in the middle gluteus and, as in plasma, a metabolic steady state was established in this muscle.
Can removal areas be used to assess dispersal of red-backed voles?
Authors: Schieck Jim O. , Millar John S.
Published: March 2009

Removal areas have often been used to assess dispersal of small rodents, although this technique has been criticized because many of the individuals recorded as dispersers may have been neighbors of the animals removed. In this study we determined the origins of red-backed voles that were caught on a removal area. Eight of 10 overwintered voles and 32 of 40 young of the year voles caught on the removal area were neighbors with activity centres within 120 m of the removal area. In addition, we compared the age–sex structure of voles immigrating into a removal area with that of voles immigrating into an unmanipulated population. The age–sex structure of voles caught on the removal area was biased towards young of the year females and against overwintered females. We conclude that the age–sex structure of voles immigrating into a removal area is not a good measure of the age–sex structure of voles immigrating into an unmanipulated population.
Neobrachiella robusta (Wilson, 1912) (Copepoda: Lernaeopodidae) as a tag for identification of stocks of its host, Sebastes alutus (Gilbert, 1890) (Pisces: Teleostei)
Authors: Leaman B. M. , Kabata Z.
Published: March 2009

Infection of Sebastes alutus (Pisces: Teleostei) with the gill parasite Neobrachiella robusta (Copepoda: Lernaeopodidae) was investigated to ascertain whether this parasite is suitable for use as a biological tag to identify stocks of its host. All copepods taken from five presumptive stocks off the coast of British Columbia belonged to N. robusta f. longidigita, but showed differences in the prevalence and intensity of infection, as well as in their population structure, that enabled these characteristics to be used for stock identification. Neobrachiella robusta was less useful as a stock identification character for individual fish when tested with discriminant function analysis. These preliminary findings show that the copepod is potentially valuable as a tool for both long- and short-term needs of fisheries management.
Urine marking by male bank voles (Clethrionomys glareolus Schreber, 1780; Microtidae, Rodentia) in relation to their social rank
Authors: Rozenfeld Francine M. , Boulangé E. Le , Rasmont R.
Published: March 2009

Available ecological data suggest that mature males of Clethrionomys species form stable hierarchical groups during the breeding season. The present laboratory work reports on the agonistic and urinary behaviour of paired, hierarchically naive, male bank voles (Clethrionomys glareolus) before, during, and after free interaction in large enclosures provided with individual burrows. In this situation, a generally stable dominance–subordination relationship is established. After a brief fighting episode, the subordinate is recognizable mainly by his avoidance behaviour out of his burrow. The subordinate's burrow itself becomes the focus of agonistic interactions. The staining of urine with unmetabolized vital dyes allowed differentiation of marking patterns. The correlation between these patterns and the hierarchical status of the animals is in accordance with the hypothesis that in bank voles, the urine of adult males contains chemical signals involved in maintaining their social organization. The spatial distribution of the urine marks of the dominant around the subordinate's nest suggests that they act as a territorial marking.
Silver staining of the cortical reaction in oocytes of Marthasterias glacialis (Echinodermata, Asteroidea)
Authors: Sousa Mário , Azevedo Carlos
Published: March 2009

Morphologically, cortical granules of the starfish Marthasterias glacialis present a lamellar structure within a dense matrix. However, with silver nitrate staining, the matrix is subdivided into argyrophilic and argyrophobic materials. Just before exocytosis the cortical granules swell. After being released in the perivitelline space, the unstained matrix disperses while the other components are incorporated into the vitelline layer. When cells are incubated with pronase before exposure to silver nitrate, no silver deposits are found.
Effects of chronic exposure to petroleum hydrocarbons on two species of marine fish infected with a hemoprotozoan, Trypanosoma murmanensis
Authors: Khan R. A.
Published: March 2009

The present study was undertaken to ascertain the effects of a blood protozoan, Trypanosoma murmanensis, on two species of marine fish exposed to petroleum hydrocarbons. Infected juvenile and adult winter flounder were exposed for 6 weeks to sediment contaminated with a Venezuelan crude (total hydrocarbon concentration, 2600–3200 μg/g) whereas Atlantic cod were exposed to water-accommodated fractions (50–100 μg/L) for 12 weeks. Three other groups, uninfected controls, fish infected with trypanosomes only, and oil-treated, uninfected fish, were held in aquaria in a continuously flowing seawater system. Mortality was higher in the infected, oil-treated flounder and subadult cod than in the trypanosome-infected only, oil-treated, and control groups. Death in oil-treated flounder was associated with severe tail rot and hypersecretion of mucus from the gills, whereas blood values (hematocrit, hemoglobin, total plasma protein) were significantly depressed in both infected groups. Low body condition, excessive mucus secretion by the gills, and retarded gonadal development were observed in adult, oil-treated cod but these were more pronounced in the infected, oil-treated groups. Prevalence of the infection and parasitemias were higher in the oil-treated groups than in untreated fish. These results provide evidence that the combined effects of parasites and chronic oil pollution can not only cause mortality but can also jeopardize health and reproduction in surviving fish.
Oxyuridan (Nematoda) parasites of Scaphiostreptus seychellarum with comments on the families Pulchrocephalidae Kloss, 1959 and Travassosinematidae Rao, 1958
Authors: Adamson Martin L.
Published: March 2009

Thelastoma retrovulvaris n.sp. and Travassosinema dechambrieri n.sp. (Oxyurida; Nematoda) are described from Scaphiostreptus seychellarum (Spirostreptida; Diplopoda) from the Seychelles. Thelastoma retrovulvaris differs from all other Thelastoma spp. except T. delphyhystera Dollfus, 1964 by the posterior position of the vulva. The latter species, not sufficiently known to permit critical comparison with the present material, is considered a species inquirenda. Travassosinema dechambrieri differs from T. travassosi Rao, 1958, type and only other species of the genus, in having coiled amphids and a shorter tail in the female and by the fact that the body narrows abruptly just posterior to the vulva. Travassosinema Rao, 1958 is characterized by the presence of a series of wing-like cuticular expansions arranged radially about the anterior extremity; such a cephalic umbraculum occurs in somewhat different form in Pulchrocephala and Indiana. Details of the cephalic umbraculum are compared in the three genera and a hypothetical transformation series is presented. A phylogenetic analysis is presented for Travassosinema, Indiana, and Pulchrocephala, and related genera Mirzaiella, Singhiella, Chitwoodiella, and Binema.
Comparative fecundity and egg survival in two stocks of goitred coho salmon (Oncorhynchus kisutch Walbaum) from Lake Erie
Authors: Leatherland John F. , Sonstegard R. A.
Published: March 2009

The reproductive success of two stocks of Lake Erie coho salmon (Oncorhynchus kisutch Walbaum) was examined in an attempt to determine if the low embryonic survival of one of the stocks could be related to the epizootic of thyroid hyperplasia exhibited by that stock. In one stock (derived from Lake Michigan and introduced annually into Trout Run, Fairview, Pennsylvania, by the Pennsylvania Fish Commission) the mortality of the embryos and yolk sac fry was significantly higher and the weight of yolk sac fry and parr was smaller than in a second self-reproducing stock which spawns in Young and Fishers creeks, Ontario. The gonadosomatic indices and number of eggs per unit weight of female were larger in the Pennsylvania stock, although carcass weights, weights of unfertilized eggs, and number of eggs per female were similar in the two stocks; secondary sexual characteristics were poorly exhibited in both stocks. There were no differences in plasma thyroid hormone levels or the degree of thyroid hyperplasia in the two stocks, suggesting that the low survival of the embryos and poor growth of the yolk sac fry in the Pennsylvania stock cannot be attributed directly to thyroid dysfunction, as had been proposed previously. Plasma thyroid hormone levels fell from relatively high levels in sexually immature salmon collected in summer to near zero levels in the pre-ovulatory to post-ovulatory salmon collected in the fall. Moreover, there was a significant decrease in plasma triiodo-L-thyronine (T3) levels in males during the period between early October and early December. No such decline was seen in females, which had low plasma T3 levels by the first (early October) fall collection.
Refractive state of the eye of the brown kiwi (Apteryx australis)
Authors: Sivak J. G. , Howland H. C.
Published: March 2009

Kiwis are flightless, nocturnal birds with relatively small rudimentary eyes. Numerous reports indicate that these birds are myopic. Refractive measurements, carried out by retinoscopy and photorefraction, on two brown kiwis (Apteryx australis) show that they are hyperopic by amounts varying between 2.3 and 7.0 diopters. This variation is presumably an indication of accommodative ability. Since the kiwi eye is relatively small and since the refractive measurements may be based on reflection from the vitreous surface of the retina, all or part of the hyperopia measured may be artifactual.
Influence of manganese, calcium, and aluminum on hydrogen ion toxicity to the amphipod Hyalella azteca
Authors: France Robert L. , Stokes Pamela M.
Published: March 2009

Experiments were undertaken to examine the influence of Mn and Ca on H+ and combined H+/Al toxicity to the amphipod Hyalella azteca in synthetic inorganic media. Aluminum concentrations of 0.25 and 0.40 mg∙L−1 at pH 4.8 and 0.40 mg∙L−1 at pH 4.3 significantly increased the rate of mortality compared with reference Al concentrations of 0.05 mg∙L−1 at these pH values. Concentrations of Al as high as 0.70 mg∙L−1 did not ameliorate H+ toxicity at pH 4.0. Toxicity was always dominated by the H+ effect. Variation in neither aqueous Ca concentration from 0.5 to 4.0 mg∙L−1 nor Mn from 0.10 to 0.40 mg∙L−1 had any significant effect on the survivorship of H. azteca exposed to lethal treatments of H+ and Al (pH 4.0–5.3; [Al] = 0.25–0.70 mg∙L−1). We predict that mortality of this amphipod from springmelt pulses will be determined primarily by [H+], and secondarily by [Al] (but only in the pH range 4.3–5.3), and will occur independently of any accompanying changes in [Ca] or [Mn].
Chromosomes du Lynx roux, Lynx rufus
Authors: Genest Fernande B. , Morisset Pierre , Patenaude Robert P.
Published: March 2009

The chromosomes of the bobcat (Lynx rufus Schreber) were studied in five males and one female. Karyotypes were obtained both from fibroblast and lymphocyte cultures. The karyotype (2n = 38) includes three morphological types: metacentrics (5 pairs), submetacentrics (11 pairs), and acrocentrics (2 pairs). The gonosomic formula is of the XY-type and both sex chromosomes are submetacentric. The X can be safely identified with G-bands, but not with standard staining techniques. The Y is the smallest chromosome within the complement. In general, the karyotype of the bobcat is similar to karyotypes of other Felidae described in the literature.
The exercise response and the "classical" diving response during natural submersion in birds and mammals
Authors: Butler P. J.
Published: March 2009

When swimming at the surface with ready access to the air, aquatic birds and mammals appear to show the typical exercise response. There are increases in oxygen uptake, heart rate, and pulmonary ventilation. These are presumably accompanied by rises in cardiac output and perfusion to the active muscles, together with a reduction in overall peripheral vascular resistance. When restrained animals are submerged under water involuntarily, total oxygen consumption is reduced below the resting level as a result of a large reduction in perfusion of most parts of the body (including skeletal muscles) except the brain and heart. The underperfused parts metabolise anaerobically, producing lactic acid, while only the brain and heart consume oxygen. The large increase in peripheral vascular resistance is compensated by a proportionally similar reduction in cardiac output which results almost entirely from a reduction in heart rate below the resting level. This is the classical diving bradycardia. Evidence is presented from a number of aquatic birds and mammals that suggests that during the vast majority of natural dives metabolism is largely if not completely aerobic with the active skeletal muscles as well as the brain and heart receiving an adequate supply of oxygen. There may, however, be a reduced blood supply to other parts of the body including to the inactive skeletal muscles. Thus during most natural dives stored oxygen is used at an elevated rate, compared with resting, and is quickly replaced upon surfacing. It is possible for the animals to perform a number of such dives in fairly quick succession. In tufted ducks, at least, there seems to be a balance between the cardiovascular response to exercise and that to involuntary submersion with the bias towards the former. This balance can be shifted in the direction of the response to involuntary submersion when the birds swim long horizontal distances for their food (e.g., under ice in winter) or if they are briefly unable to surface (e.g., if rising vertically beneath ice).
The behavioral ecology of air breathing by aquatic animals
Authors: Kramer Donald L.
Published: March 2009

Behavioral ecology uses general principles of economic design to generate testable predictions for animal activities in particular environmental situations. Sociobiology and optimal foraging, the two most developed areas of behavioral ecology, use very similar models of resource gain maximization to investigate patterns of mating and energy acquisition, respectively. Here, I consider the relevance of these principles to the uptake of oxygen by air-breathing aquatic organisms. The behavior of bumblebees foraging for foxglove nectar illustrates the principle of optimal exploitation of aggregated resources. When applied to the acquisition of oxygen at the water surface by diving animals, this principle predicts that with increasing distance to feeding sites or other areas of resource gain, the bout lengths of surface time and dive time will increase, as will percent time at the surface; swimming speed may increase or decrease depending on the costs of acceleration. Principles of the allocation of effort predict that in bimodal organisms the use of air will decrease and the use of dissolved oxygen will increase as depth increases. Empirical field and laboratory studies provide some support for these predictions in a variety of mammals, birds, reptiles, amphibians, and fishes. A "theory of optimal breathing" is relevant to physiology because it uncovers interesting and unexpected subtleties in the regulation of respiration, because it provides a holistic framework in which to order empirical findings, because it pinpoints potentially confounding variables in experimental studies, and because it illustrates the value of a hypothetico-deductive approach to adaptation.
Control of arrhythmic breathing in aerial breathers
Authors: Milsom William K.
Published: March 2009

Arrhythmic breathing patterns of two basic types occur among the air-breathing vertebrates. These patterns, which appear to be dependent more on inputs from peripheral receptor groups than on a central generator, allow significant fluctuations in the partial pressures of O2 and CO2 in lungs, blood, and tissues with accompanying fluctuations of pH in body fluids. The major components of each pattern are the size and timing of each breath, the length of each episode of breathing, and the length of the pause between episodes of breathing. While each of these components appears to be under separate control, the relative roles of the various receptor groups in the control of each remain unclear. Similarities between data collected from reptiles and hibernating mammals suggest that the arrhythmic breathing patterns seen under physiological conditions in all air-breathing vertebrates may be manifestations of a common control system. The conversion from continuous to arrhythmic breathing seen in mammals entering hibernation further suggests that both continuous and arrhythmic breathing are manifestations of a common control system. The two distinct arrhythmic breathing patterns appear to arise from differences in the supramedullary integration of vagal input in different species. It is suggested that under conditions of reduced metabolic demand, these arrhythmic breathing patterns may represent an adaptive strategy which, in part, serves to reduce the energetic cost of ventilation.
Gas exchange and its control in non-steady-state systems: the consequences of evolution from water to air breathing in the vertebrates
Authors: Shelton G. , Croghan P. C.
Published: March 2009

Control of breathing and gas exchange has been extensively investigated in unimodal animals, particularly mammals, in which ventilation is characteristically a regular and continuous process and gas exchange approximates to a steady-state system. Both static and dynamic models have been developed in control-theory analyses. Similar analyses are possible in unimodal fish, though few have been carried out. Control in bimodal animals, such as air-breathing fish and amphibians, is more difficult to understand and model. The evolutionary change from water to air breathing in vertebrates involves not only the adjustment of many control processes but also the development, in the early stages, of non steady states in gas exchangers, blood, and tissues. A simple control-system model, differing from mammalian counterparts in its greater emphasis on storage functions and its intermittently activated controller, is described for two suggested stages in the evolution of air breathing. The first of these stages is air gulping, in which a fixed and rather brief pattern of air breathing is activated by internal signals generated as a result of the inadequacy of the gills to provide sufficient oxygen for tissue metabolism. The second stage is that of burst breathing, in which lung ventilation is both begun and ended by internal signals so that burst duration is variable. The effects of adjusting parameters on variables of evolutionary importance, such as dive duration, burst duration, store renewal, and metabolic rate, can be examined in these two versions of the model. Refinements to incorporate arterial and venous compartments in the circulatory system, the shunting of venous and arterial blood streams in the heart, realistic oxygen dissociation curves, controller inputs from a wider range of sources, and the capacity to respond to some conditions with changes in ventilation rate as well as in burst and dive durations, are being developed. They should make the complex, non-steady-state interactions between gas exchangers, circulating blood, and tissues easier to understand and indicate the likely steps toward the evolution of steady-state systems seen in birds and mammals.
Suspended animation: the molecular basis of metabolic depression
Authors: Storey Kenneth B.
Published: March 2009

An impressive array of organisms is capable of radically depressing basal metabolic rate and entering a hypometabolic state characterized by a marked reduction of many normal physiological functions. Environmental cues are often the trigger: low oxygen, low temperature, or lack of water, for example. Entry into a hypometabolic state does not, apparently, involve major biochemical reorganization but appears, instead, to result from molecular controls operating at a level "above" that of allosteric regulation of enzymes and "below" that of gene expression. The mechanisms involved are widely applicable to the coordinated inactivation of many cellular processes. Studies of anaerobiosis in marine molluscs provide the most complete information on the molecular mechanisms involved in metabolic rate depression. Glycolytic rate depression in the marine whelk involves (i) covalent modification of key regulatory enzymes (e.g., phosphofructokinase, pyruvate kinase) via enzyme phosphorylation to produce less active enzyme forms, (ii) dissociation of enzymes from complexes bound to the subcellular particulate fraction to disrupt pathway flux, and (iii) decreased levels of fructose-2,6-bisphosphate, a potent activator of phosphofructokinase, to help limit the anabolic uses of carbohydrate in the depressed state. Continuing studies are demonstrating the universality of these mechanisms as the basis of metabolic depression, including involvement in mammalian hibernation and anoxia tolerance in goldfish and turtles.
Periodic respiration of gill-breathing fishes
Authors: Roberts John L. , Rowell David M.
Published: March 2009

Rhythmic and arrhythmic patterns of breathing are common among gill-breathing fishes. Irregular, short bouts of apnea occur in most fishes during feeding, while long apneic periods are routine for many open-water fishes such as scombrids, which ram ventilate during cruise swimming. During ram ventilation, the work of gill ventilation is transferred from the respiratory to the swimming musculature, with energy savings due to reductions in drag and inertial losses. Noncontinuous swimmers, such as some benthic and midwater marine and freshwater species, seldom cease rhythmic respiratory movements or resort to ram ventilation. When quiescent, they may adopt patterns of secondary cycling, alternating between respiratory pauses and short periods of rhythmic branchial pumping. Types and locations of chemo- and mechano-receptors that trigger changes in respiratory patterns of fish are being identified, as are the reflex pathways linking them to brainstem respiratory centers. A new mechanoreceptor is described that overlies the adductor mandibulae jaw muscles and may be of use in the modulation of cyclic respiratory movements. Respiratory switching control between rhythmic and ram gill ventilation is discussed.
American Redstart nest placement in southwestern New Brunswick
Authors: Morris Michael M. J. , Lemon Robert E.
Published: March 2009

We gathered data from 208 American Redstart (Setophaga ruticilla) nests from 1979 to 1985 in southwestern New Brunswick to examine patterns in nest-tree features. Most nests were located in either speckled alder (30.7%) or white birch (22.1%). Nest-site features (nest height, relative nest height, nest access distance) were relatively consistent for those nests located in some tree taxa (alder) but considerable intrataxa variability (cedar, white birch) and several significant intertaxa differences were observed. These differences may reflect each species' branching geometry. Our data were not entirely consistent with existing models of nest-height distribution.
The composition of hooded seal (Cystophora cristata) milk: an adaptation for postnatal fattening
Authors: Oftedal Olav T. , Boness Daryl J. , Bowen W. Don
Published: March 2009

We obtained milk from 22 hooded seals on pack ice off the southeast coast of Labrador. Milk composition was not affected by degree of mammary evacuation or method of milk collection (drug immobilization vs. postmortem collection). Lactation stage exerted relatively little influence on milk composition over the course of the 4-day lactation period, but colostrum was higher in crude protein content. At mid to late lactation (2 – 4 days postpartum), hooded seal milk contains the highest dry matter (70%), fat (61%), and gross energy (5.9 kcal/g) contents that have been reported for any mammalian milk. This high fat content may be essential to achievement of the extremely rapid rate of fat deposition (about 4 kg/d) by suckling pups. The relatively low protein content (4.9%) at mid to late lactation is consistent with the small proportion of postnatal weight gain that is lean body mass. The proportion of milk energy contributed by protein is the lowest known for any mammal.
Reproductive biology of a cave-associated population of the frog Rana palustris
Authors: Resetarits Jr. William J. , Aldridge Robert D.
Published: March 2009

Aspects of the reproductive biology of a trogloxene population of the pickerel frog, Rana palustris (Anura: Ranidae), were studied at a cave on the edge of the Ozark plateau in Missouri. Sexual dimorphism in body size was marked; there was almost no overlap in adult body size ranges, and the ratio of mean adult female snout–vent length (SVL) to adult male SVL was 1.26. All males with SVL of >45 mm were sexually mature. Males showed a clear cycle of spermatogenesis, with a peak in midsummer and a decline in spermatogenic activity through autumn and winter. Minimum size at maturity for females was 59 mm SVL. Females completed vitellogenesis during the summer, before their arrival at the study site. Of 28 females above the minimum size at maturity, 27 contained egg clutches. Clutch size, clutch mass, and egg size (mass) show significant positive correlation with SVL. Mean (±SD) clutch size was 1759 ± 548. Fat bodies were present in both males and females in autumn, but were totally depleted before the animals emerged from hibernation. Trogloxene R. palustris do not diverge significantly from patterns of reproductive biology typical of other temperate zone Rana. Current or past patterns of cave use have had no detectable effect on reproductive characteristics of trogloxene R. palustris.
Ecology of gyrfalcons, Falco rusticolus, in the central Canadian Arctic: diet and feeding behaviour
Authors: Poole K. G. , Boag D. A.
Published: March 2009

Diet and aspects of feeding behaviour in a population of gyrfalcons (Falco rusticolus) in the Northwest Territories were examined between 1984 and 1986. Three prey species, rock ptarmigan (Lagopus mutus), arctic ground squirrel (Spermophilus parryii), and arctic hare (Lepus arcticus), composed 96.5% of total prey biomass identified. Ptarmigan and hares were taken in May and June of all years (98.2% of biomass). Juvenile squirrels were used extensively in July and August of 1984 and 1985 but not in 1986, when squirrel production fell to almost zero; ptarmigan continued to be the dominant prey species throughout that summer. Because densities of breeding ptarmigan remained relatively constant during the study, but those of juvenile ground squirrels did not, it appeared that gyrfalcons responded functionally to varying availability of prey. Mean weight (250 g) of prey taken by male gyrfalcons was significantly less than the weight (330 g) of prey taken by females. As predicted by optimal foraging theory, average size of prey brought to the nest increased as time away from the nest increased. Conditions of food abundance were observed at most nests, suggesting that the amount of food available during the nestling period was not limiting production. We suggest that annual production is a function of spacing of pairs, which is set during courtship and prelaying, when prey availability is at its yearly low and when males must forage for both members of the pair. The fact that most gyrfalcon pairs initiated laying only after the spring arrival of migrating ptarmigan is consistent with this conclusion.
Anion-stimulated ATPase in locust rectal epithelium
Authors: Lechleitner R. A. , Phillips J. E.
Published: March 2009

The rectum, the main reabsorptive site in the locust excretory system, actively transports Cl−. This Cl− absorption is electrogenie, not dependent on Na+or [Formula: see text] and insensitive to inhibitors of NaCl cotransport or [Formula: see text] exchange. To determine if active Cl− transport across rectal epithelia might be due to an anion-stimulated ATPase, a microsomal fraction was obtained by differential centrifugation. Microsomal ATPase activity was stimulated in the following sequence: sulphite > bicarbonate > chloride. Maximal ATPase activity was obtained at 25 mM [Formula: see text] or 25 mM Cl−. Thiocyanate (10 mM) inhibited 90% of the anion-stimulated ATPase activity. The microsomal fraction was enriched in the plasma membrane markers, leucine aminopeptidase, alkaline phosphatase, 5′-nucleotidase, and γ-glutamyItranspeptidase, and had little contamination of the mitochondrial enzymes, succinate cytochrome c reductase and cytochrome oxidase. Na,K-ATPase was enriched in the mitochondrial fraction. Microscopic examination confirmed that basolateral membranes were associated with mitochondria following differential centrifugation, while the microsomal fraction contained little mitochondrial contamination. These results indicate the presence of an anion-stimulated ATPase activity that could be responsible for active Cl− transport across locust recta.
Prey handling time in two piscivores, Esox americanus vermiculatus and Micropterus salmoides, with contrasting mouth morphologies
Authors: Hoyle James A. , Keast Allen
Published: March 2009

An experimental study was carried out on prey handling time (from initial seizure of prey to completion of swallowing movements) in the grass pickerel (Esox americanus vermiculatus), using bluegill (Lepomis macrochirus) as prey. Esox differs from the largemouth bass (Micropterus salmoides), which was studied previously, in having a more specialized dentition. It was found that for individuals of the same mouth width (20 mm), handling time was 40–80% less in Esox for bluegill prey of total length 20–50 mm. Further, "optimal" and maximum size of prey consumed were 56 and 46% larger, respectively, for the esocid. The results are also related to body weight and age in Esox and Micropterus and the ecological significance of the findings is discussed.
Reproductive strategies of ectoparasites on small mammals
Authors: Lundqvist Lars
Published: March 2009

A model of ectoparasitic reproductive strategies is presented. To be successful, an ectoparasite must either disperse to find a new host or stay on one host and produce its progeny during the lifetime of the host. Dispersion is facilitated by utilizing many host species and by waiting for the next host; these strategies prolong the generation time. Staying on the host is facilitated by shortening the generation time. Ectoparasites that repeatedly move on and off hosts are thus expected to have wide host preference spectra and long generation times while sedentary ectoparasites are expected to have narrow host preference spectra and short generation times. Population parameters of 27 ectoparasitic species (fleas, lice, mesostigmatic mites, and one ixodid tick species) on cyclic small mammal populations were investigated and a cluster analysis was performed. Three population parameters proved to be important and could be used to form a base for life-trait grouping of the ectoparasites: (i) the host preference spectra; (ii) the time lag between host and parasite peak abundance; and (iii) the intensity of the infestation. Three groups of ectoparasitic life traits were discernible: (i) species with narrow host preference spectra, no time lag (short ectoparasitic generation time), and major infestation: the Anoplura–Laelapinae group; (ii) species with moderate to wide host preference spectra, 1-year time lag (long parasitic generation time), and minor infestation: the Siphonaptera–Haemogamasinae group; (iii) one species, Ixodes trianguliceps, had moderate host preference spectrum, 2-year time lag, and moderate infestation. Ectoparasites, such as trombiculid mites and the tick Ixodes ricinus, which are not confined to small mammals, were missing or very rare on the cyclic small mammal populations. This was predicted by the model.
Relationships among egg size, energy reserves, growth rate, and fasting resistance of Canada Goose goslings from southern Ontario
Authors: Thomas V. G. , Brown H. C. Peach
Published: March 2009

Eggs of wild giant Canada Geese (Branta canadensis maxima) breeding in southern Ontario were collected and incubated artificially. Components of the total nutrient reserve of goslings were measured at hatch to test whether relationships existed between egg size, gosling weight, and weight of reserves in goslings. The growth rate of fed goslings of different weights at hatch was measured for 25 days. The nutrient reserves remaining in goslings of different hatch weights were measured after 2, 4, and 6 days of starvation. Egg size and gosling weight were not highly correlated in this population (r = 0.63). Larger goslings generally contained more reserves than small goslings (P < 0.05), but much variability occurred in this relationship. Gain in weight over 25 days was not related to the weight at hatch. Starved goslings with higher body fat levels had significantly higher dry carcass weights than goslings with low body fat levels (P < 0.01), suggesting a sparing action of fat on body tissues. The apparent survival of small goslings and goslings with small reserves, combined with the great variability in egg size, gosling weight, and extent of metabolic reserves, suggests relaxed selection in the southern Ontario environment where this population breeds.
Structural correlates of photoresponse in trochophore larvae
Authors: Lacalli Thurston C.
Published: March 2009

Electron microscopic reconstructions of larval ocelli from two polychaete species show a correlation between pigment cup orientation and larval photoresponse. Phyllodoce maculata larvae are strongly photopositive and their ocellar receptor cell is shaded from above. Spirobranchus polycerus larvae are photonegative and their receptor cell is shaded from below. The results support a hypothesis developed by Marsden and Hsieh (Marsden, J. R., and Hsieh, J. 1987. Zoomorphology (Berlin), 106: 361–368), which states that larvae undertake extended swimming only when the eyespot, i.e., the receptor cell, is maximally shaded.
Adaptation and evolution of mitochondria: osmotic and ionic considerations
Authors: Ballantyne J. S. , Chamberlin M. E.
Published: March 2009

Mitochondrial evolution has been examined on the basis of properties of mitochondria from representatives of key adaptive stages. The major step in the evolution of mitochondria was the transfer of mitochondrial genes to the nucleus to take advantage of recombination during meiosis. The ensuing increase in variability facilitated adaptation to environmental stress. The role of environmental factors such as atmospheric oxygen levels in the evolution of mitochondria is discussed on the basis of evidence obtained from mitochondria of living representatives of important groups and the fossil record. Rate enhancement has been a central theme in the evolution of animal mitochondria. Optimization of mitochondrial oxidation rates occurred through adjustments in intracellular solute systems. This took place in several stages, including (i) a reduction of intracellular inorganic ion levels by substitution of a variety of compatible solutes, (ii) a counteracting solute system (urea and methylamines), and (iii) osmoregulation.
Fermentative adaptations to the lack of oxygen
Authors: Fields Jeremy H. A.
Published: March 2009

Survival of organisms in the absence of oxygen depends on their ability to ferment substrates. The fermentative pathways start with substrates, such as carbohydrates, that are rich in hydroxyl groups and that can undergo oxidation or reduction reactions. The limit of the oxidations is the production of a carboxyl group, and the limit of the reductions is the formation of saturated carbon chains. When these limiting factors are combined, the furthest that the reactions can be taken is the production of fatty acids. The excess energy produced by the oxidations over that used by the reductions is used for the production of adenosine triphosphate for other metabolic demands. Invertebrates have exploited several combinations of these reactions, and this is reflected in the many different end products that they produce.