bluuebunny/crossref_metadata_2025 huggingface dataset:
Selective predation on cladocerans by common pond insects
Authors: Cooper Scott D.
Published: January 2010

A variety of common pond insects was presented with a mixture of different size classes of Daphnia magna or different sizes of Daphia pulex, Moina affinis, and Ceriodaphnia sp. in predation trials. Juvenile Belostoma flumineum and most instars of Notonecta undulata and Anax Junius fed at the highest rates on the largest available cladoceran prey, and late-instar Buenoa corfusa fed at the highest rates on prey between 0.8 and 2.0 mm in length. Predation rates of instar IV Chaoborus americanus larvae were highest on Daphnia < 1 mm in length, and lowest on Daphnia > 2 mm in length. First-instar Chaoborus larvae did not eat cladocerans in these trials. The size-selective feeding patterns exhibited by Notonecta adults and late-instar Anax were similar in the light and dark, although overall feeding rates were depressed in the dark. Buenoa, on the other hand, only exhibited size-selective feeding in the light. The results indicate, however, that all of these insect predators can feed in the dark. Predation rates for late-instar Chaoborus larvae were unaffected by light conditions or the presence of filamentous algae. Chaoborus larvae were readily eaten by late-instar Notonecta and Anax.
Growth and reproduction of Macoma balthica (L.) on a mud flat in the Fraser River estuary, British Columbia
Authors: McGreer E. R.
Published: January 2010

Growth and reproduction of the bivalve, Macoma balthica (Linnaeus, 1758) was studied for one year (April 1977 – March 1978) on an intertidal mud flat in the Fraser River estuary, British Columbia. The maximum number of individuals (1830/m2) occurred in April, then steadily declined throughout the year. Spawning occurred between mid-June and late July but recruitment was slow and prolonged. Peak spatfall (age 0+ individuals) did not occur until the following March when a maximum density of only 410/m2 for newly settled spat was observed. The oldest animals found were 5+ years of age. Maximum growth took place from April through July. The growth rate measured was one of the highest recorded for any M. balthica population. A direct relationship between high water temperatures, a fast growth rate, and reduced longevity was apparent. A regression of body weight on shell height was used to calculate a condition factor (CF), which reached its highest value during growth and its lowest value immediately after spawning. The mean annual biomass measured was 2.96 g dry weight per square metre.
Some effects of the cestode (Schistocephalus solidus) on reproduction in the threespine stickleback (Gasterosteus aculeatus): evolutionary aspects of a host–parasite interaction
Authors: McPhail J. D. , Peacock S. D.
Published: January 2010

Monthly samples of threespine stickleback (Gasterosteus aculeatus) were collected from May through September 1975 from Fuller Lake, Vancouver Island. A total of 2175 adult sticklebacks were collected from 10 trap sites located at depths ranging from 0.25 to 5 m. These samples were assayed for length, weight, sex, state of maturity, and egg number (when applicable). In addition, we recorded the number and weight of the plerocercoids of a cestode tapeworm (Schistocephalus solidus) often found in the abdominal cavities of sticklebacks. The purpose of the study was to document the effects of Schistocephalus on reproduction in Gasterosteus. Stickleback spawning reached a peak in June and declined sharply through July and August. Over the entire breeding season, less than 5% of the gravid females were infected with Schistocephalus, whereas over 40% of the sexually mature but nongravid females were infected. There was no difference between breeding and nonbreeding males in the prevalence of Schistocephalus. In both sexes, the prevalence and severity of Schistocephalus infection were low in May, June, and July but increased sharply through August and September. Since the majority of Fuller Lake sticklebacks live for 1 year, the major adverse effects of Schistocephalus were confined to postreproductive adults. We hypothesize that Schistocephalus plerocercoids have been selected to delay adverse effects on their host until after the host has reproduced.
Polymorphism of microtriches in the cysticercoid of Ophryocotyle insignis Lonnberg, 1890 from the limpet Patella vulgata
Authors: MacKinnon Barbara M. , Burt Michael D. B.
Published: January 2010

The mature cysticercoid of Ophryocotyle insignis, from Patella vulgata, was examined using transmission electron microscopy. Eight different types of microtriches were present over the tegument of the larval body and microvilli covered the caudal bladder, or cercomer. Rounded, modified microtriches were present on the external surface of the bladder enclosing the cysticercoid. Microtriches lining the retraction chamber ranged from small triangular projections having an electron-dense ridge along the anterior margin but having no shaft, to more typically shaped, larger microtriches having a cytoplasmic base, electron-dense shaft, and an electron-dense ridge along the anterior margin of the base. The scolex tegument had large robust microtriches which, in transverse section, had many projecting flanges. The microtriches on the rostellum were long and slender. Long, thin microtriches were present amongst the small spines on the suckers and short microtriches were found on the unspined areas of the suckers. Possible functions for the different types of microtriches are suggested and the significance of microvilli on the cercomer is discussed.
Macrobenthic abundance and distribution in tidal pools of a Quebec salt marsh
Authors: Ward G. , FitzGerald G. J.
Published: January 2010

The abundance and distribution of macrobenthos in tidal pools of different sizes and physical–chemical conditions were examined in a salt marsh near Isle Verte, Quebec. The underlying purpose of the study was to determine if the macrobenthic community was the same among tidal pools regardless of their location, size, or physical–chemical conditions. Three hypotheses were examined relating to concepts of stability–diversity, island biogeography, and environmental gradients: (i) that the macrobenthic community of small tidal pools contains fewer species than that of larger pools; (ii) that numbers of macrobenthic species increase with pool size; and (iii) that macrobenthic species composition in pools nearest the Estuary is different from that of high marsh pools. No consistent differences in the macrobenthic community were found between pool sizes. Pools situated closer to the St. Lawrence Estuary had a slightly different fauna than the more inland pools owing to different flooding regimes. Oligochaetes (Tubificidae), the gastropod Hydrobia minuta, and Chironomus sp. larvae were the dominant organisms of the marsh. There was a negative correlation between the abundance of chironomid larvae and interstitial water salinity, and a positive correlation between polychaete abundance and overlying water salinity. A negative correlation was also observed between the occurrence of Chironomus sp. and Culicoides sp. (Diptera) which may have been due to biotic factors. Varying interstitial salinities were found amongst regions of large pools, possibly due to floodwater transport mechanisms in the marsh.
Morphology of the tapetum fibrosum in the eye of the domestic sheep
Authors: Braekevelt C. R.
Published: January 2010

The fine structure of the tapetum lucidum of the domestic sheep was studied by both light and electron microscopy. In this species the reflective layer is a tapetum fibrosum situated in the choroid and restricted to the superior fundus. The tapetum is composed of a large array of fine extracellular collagen fibrils partially separated into lamellae 2–5 μm thick by fibrocytes. The collagen fibrils display the normal cross striations of native collagen, are 0.2 μm in diameter, and are arranged in a hexagonal pattern with a space of 0.2–0.25 μm between fibrils. The diameter and spacing of these fibrils is consistent with the constructive interference of reflected light. A vascular lamella adjacent to the retinal epithelium contains the choriocapillaris, pericytes, and irregularly arranged collagen fibrils. Over the tapetum the retinal epithelium is nonpigmented while in nontapetal regions it is pigmented. Bruch's membrane is pentalaminate in both tapetal and nontapetal regions.
A world review of the simplex species group in the genus Typhlodromus Scheuten (Acarina: Phytoseiidae)
Authors: Chant D. A. , Yoshida-Shaul E.
Published: January 2010

The simplex species group is described on a worldwide basis. There are six species in the group as presently conceived, including a new species: Typhlodromus arzakanicus (Arutunjan), T. calabriae (Ragusa &Swirski), T. carmonae n. sp., T. peculiaris Kolodochka, T. simplex (Chant), and T. subsimplex (Arutunjan). A brief introduction to the various generic concepts of different authors is given in relation to the species which belong to the simplex group, and the basic characters of the group are outlined. A key to adult females is provided and morphological descriptions of the six species are given. Descriptions of the three species which we were unable to examine are based on the original descriptions and illustrations.
Some potential mosquito vectors of the canine heartworm, Dirofilaria immitis, in the Calgary region of southern Alberta
Authors: Frimeth Jack P. , Arai Hisao P.
Published: January 2010

A total of 657 mosquitoes, representing eight species from the Calgary region of southern Alberta was fed on dogs infected with Dirofilaria immitis. Complete development to the infective stage occurred in Aedes campestris, A. cataphylla, A. flavescens, and A. vexans. The rate of development appeared dependent on the temperature, as well as on the vector species. This report is believed to be the first account on the development of D. immitis in the first three species. Third stage larvae recovered from A. flavescens and A. vexans, inoculated subcutaneously into either two dogs or two white laboratory rats, produced microfilaremias in both dogs and a single adult, male D. immitis in the thoracic cavity of one of the rats. It is suggested that these species may act as vectors under natural conditions and that the identification of the potential vectors of D. immitis in areas where it is currently not endemic is important since this knowledge can be used in the planning of prophylactic measures.
Relation of geographic variation in the skull of Microtus pennsylvanicus to climate
Authors: Snell Richard R. , Cunnison Kimberly M.
Published: January 2010

Analyses of geographic variation in the skull of meadow voles (Microtus pennsylvanicus) indicate that phenetic distances among samples are not related to geographic distance: a minimum spanning tree based on average taxonomic distance superimposed on a map of 38 localities provides no particular phenetic clustering of those samples geographically proximate. A multiple regression of phenetic component one (skull size) onto orthogonally rotated climatic factors explains much less morphometric variation (25.6%) than a simple correlation with recorded extreme low temperature (38.9%). Multiple regression of phenetic principal component two (interorbital width) onto the same climatic factors explains minimally more morphological variation (42.1%) than a simple correlation with mean annual number of days with frost (41.7%). Microtus pennsylvanicus shows a pattern of size variation that is the reverse of Bergmann's rule: these voles are large where it is warm and small where it is cold. Since small size reduces total energy expenditure, we predict that during times of extreme low temperature (i) smaller voles will be less energetically stressed than larger voles and (ii) large size will be actively selected against.
Seasonal levels of fat and protein reserves of snowshoe hares in Ontario
Authors: Whittaker M. E. , Thomas V. G.
Published: January 2010

Neutral lipid and protein levels were measured in snowshoe hares collected from a dense population at Kirkland Lake, Ontario, during the summer of 1980 and the winter and spring of 1981. The potential metabolic support provided by the oxidation of neutral lipids and protein was calculated from these values. The fat levels of hares were low, 30 g (2.5% of the body weight), and showed little variation by gender or season. Carcass protein levels were approximately 20% of the wet carcass weight in both genders and did not vary seasonally. These reserves together represent about 4 days' resting metabolic support during winter, 4 to 5 days' support under spring conditions, and 6 days' support under summer breeding conditions. The weight of selected major skeletal muscles and organs did not vary seasonally in either gender, indicating that hypertrophy and proteolysis were not occurring in this population. These metabolic reserves would not buffer chronic dietary inadequacies during winter existence and reproduction, and snowshoe hares must adopt a foraging strategy which maintains energy and nitrogen balance on a very short-term basis.
Mechanics and energetics of medusan jet propulsion
Authors: Daniel Thomas L.
Published: January 2010

A theoretical model is developed to describe the mechanics and energetics of medusae which swim by jet propulsion. The model leads to four generalizations: (i) The acceleration reaction, not drag, is the dominant fluid force experienced by swimming medusae. (ii) There exist behaviors such as contraction time and relative duration of the relaxation of contraction phases which maximize the velocity and efficiency and minimize the cost of locomotion during normal swimming. Also, escape performance is maximized with certain behaviors. Existing data for medusae show that many operate near these optima. (iii) The ratio of efficiency to cost of locomotion is a reasonable measure of swimming behavior and provides a means to study the relationships between swimming behavior and size, (iv) For medusae of a particular shape exhibiting a particular swimming behavior there exists a unique size which maximizes the ratio of efficiency to cost of locomotion.
The induction of metamorphosis of marine invertebrate larvae: stimulus and response
Authors: Burke Robert D.
Published: January 2010

The induction of metamorphosis by environmentally derived cues is reviewed in barnacles, molluscs, hydroids, echinoids, and ascidians in the context of the neurological and behavioral model of stimulus and response. The model proposes that cues associated with preferred juvenile or adult habitats are the stimuli. Stimuli are received by receptors that communicate with the effectors of metamorphosis, larval and adult tissues. The response is a combination of morphogenetic, histolytic, and histogenic processes. Receptors in all five taxa are assumed to be superficial sensory receptors, though there is no direct evidence for their involvement in the perception of cues. Although the induction of metamorphosis by environmental cues in all five taxa fits well within a stimulus–response model, there is currently only circumstantial evidence for neural or endocrine control of metamorphosis.
Accelerated circannual cycles in ground squirrels, Spermophilus richardsonii, kept in constant conditions
Authors: Melnyk Roman B.
Published: January 2010

Six- to 8-month cycles of food intake, body weight, moult and reproductive condition in captive Richardson's ground squirrels (Spermophilus richardsonii) kept in 12 h light: 12 h dark and 23 ± 3 °C for over a year are described. A decrease in efficiency of food utilization towards the end of the weight gain period may be associated with metabolic processes which determine an upper limit for body weight. The advantages of this species as a model for the study of spontaneous obesity are discussed.
Sex- and age-specific reproductive and physical parameters of the bobcat (Lynx rufus) on Cape Breton Island, Nova Scotia
Authors: Parker G. R. , Smith G. E. J.
Published: January 2010

A total of 605 bobcat (Lynx rufus) carcasses, collected by trappers on Cape Breton Island from 1977–1978 through 1979–1980, were examined for sex and age structure, physical characteristics and condition, diet, and reproduction. The overall sex ratio was 52 males to 48 females; sex ratios favoured males in the juvenile cohorts and females in adult classes. Annual survival rates for adult males and females were 0.58 and 0.63, respectively. Kits were underrepresented and yearlings overrepresented in the annual harvests. The oldest bobcats were aged at 11.5 years. Females produced their first litters at 1 or 2 years of age. Breeding rates for 1-, 2-, and 3-year-old bobcats were 26, 55, and 73%, respectively. For those three age-classes, in utero litter sizes were 2.22, 2.43, and 2.74, respectively. Litter sizes ranged from 1 to 6. Snowshoehare (Lepus amer ic anus) was the most important food item in the winter diet; annual percent occurrence values ranged from 83 to 92%. The proportion of yearlings in the monthly samples declined through the winter while the proportion of kits increased. Options for regulating the composition of the harvest through flexible seasons are discussed.
Évolution, à court terme, des communautés zooplanctoniques de deux rivières du nord Québécois soumises à une forte réduction de débit
Authors: Armengol J. , Moreau G. , Planas D.
Published: January 2010

A decrease of 86 to 92% in the flow of two rivers in the James Bay area resulted in a 7.5- to 9.8-fold increase in density of zooplanctonic populations and in a 2.5- to 6.3-fold increase in their biomass. Differential increases of numbers and biomass are attributed to a proportionately higher increase of the protozoans and rotifers. The overall effect of the reduced flow seems to be the same at all stations; however, local characteristics may modify the responses of the communities. Turbulence, quantity of suspended matter, and evolution of the phytoplancton seem to be the major parameters regulating the community responses.[Journal translation]
An electrophoretic, morphological, and ecological investigation of a putative hybrid zone between Myotis lucifugus and Myotis yumanensis (Chiroptera: Vespertilionidae)
Authors: Herd Robert M. , Fenton M. Brock
Published: January 2010

In the Okanagan valley of British Columbia, Myotis lucifugus and Myotis yumanensis are sympatric and some individuals are intermediate in typical morphology. A survey of electrophoretic variation at 31 protein loci of intermediate bats indicates no evidence of hybridization. Discriminant analysis on these specimens shows better separation by skull characters than by external measurements, but 13 bats (14% of 93 examined) were designated as intermediate and 7 could have been labelled hybrids. Absence of electrophoretic evidence of hybridization indicates that similar morphology reflects overlap in extremes of intraspecific morphological variation. Myotis lucifugus was trapped in the western foothills adjacent to the Okanagan River and foraged in all of the habitats we sampled. Myotis yumanensis was only trapped in the valley and preferred to forage over flowing water. There was no evidence of agonistic interactions between the two species. The composition of the diets in M. lucifugus and M. yumanensis changed over the course of this study and there were significant differences in the proportions of insect taxa consumed by the two species. Parturition in M. lucifugus commenced after mid-June and most females did not produce offspring until their 2nd year, whereas parturition in M. yumanensis commenced in early June and female offspring gave birth in their 1st year.
Diagnostic characteristics of Dirofilaria subdermata in cross sections
Authors: Gutierrez Yezid
Published: January 2010

A study of morphological characteristics in cross sections of Dirofilaria subdermata adults from the subcutaneous tissues of the Canadian porcupine (Erethizon dorsatum) is reported. A useful diagnostic feature which differentiates D. subdermata from a closely related filarid, D. ursi, occurring in bears, was found to be the number of longitudinal ridges. The relevance of these findings are discussed in relation to the human subcutaneous infections found in the United States and Canadian border states and provinces with D. ursi.
Redescription of Capillaria serpentina Harwood, 1932, (Nematoda: Trichuroidea) from freshwater turtles in Virginia
Authors: Platt Thomas R.
Published: January 2010

Capillaria serpentina Harwood, 1932, is redescribed from specimens collected from Chelydra s. serpentina, Chrysemys p. picta, and Sternotherus odoratus from Westhampton Lake, Richmond, Virginia. Worms were found in the mucosa and submucosa of the small and large intestine. Comparisons of worms from different hosts and locations within hosts revealed no differences that would warrant establishment of new taxa. Chrysemys p. picta and S. odoratus are new host records and Virginia is a new locality record for this nematode.
Geographic variation in the underwater vocalizations of Weddell seals (Leptonychotes weddelli) from Palmer Peninsula and McMurdo Sound, Antarctica
Authors: Thomas Jeànette A. , Stirling Ian
Published: January 2010

The Weddell seal (Leptonychotes weddelli) is one of the most vocal pinnipeds. The repertoires of subice vocalizations of Weddell seals recorded at Palmer Peninsula and at McMurdo Sound, Antarctica, are different. Although seals at both sites give some of the same vocalizations, there are subtle spectral and temporal differences. In addition each population has unique vocalizations which are not heard at the other site. At Palmer Peninsula, there are several usage characteristics not exhibited at McMurdo Sound, such as mirror-image vocalization pairs and vocalization trios. Weddell seals in McMurdo Sound make extensive use of nine auxiliary sounds, while the Peninsula repertoire has none. Factors which appear to have been important in the development of these geographic differences appear to include strong fidelity to breeding sites, a polygynous mating system, and learning. Geographically different vocal repertoires have potential for identifying discrete breeding stocks of Antarctic seals.
The biology and zoogeography of Helicopsyche borealis (Trichoptera: Helicopsychidae): a Nearctic representative of a tropical genus
Authors: Williams D. Dudley , Read A. T. , Moore K. A.
Published: January 2010

Members of the caddisfly family Helicopsychidae were present in the Upper Jurassic, and the present-day distribution of the genus Helicopsyche shows typical southern continent dispersion, suggesting that it was in existence before the breakup of Pangea. Most of the approximately 90 species of Helicopsyche are endemic to the tropics, indicating a tropical origin for the genus. At certain locations, e.g. Mexico, Sri Lanka, and New Caledonia, pronounced speciation has occurred. Only two species have successfully colonized North Temperate regions, H. borealis in North America (the most widespread species) and H. sperata in Europe. In a stream in southern Ontario, H. borealis is probably univoltine although difficulty in separating instars complicates interpretation. Dyar's Rule was applied to assist in this interpretation. Microdistribution of larvae in the stream was examined and microcurrent regime around single rocks was judged to be an important controlling factor. Microdistribution extended into the hyporheic zone of the stream bed. The ability to live interstitially is proposed to explain the unique helical shape of the larval case as the case is very resistant to crushing. Case composition was very similar in 5th instar individuals. Larvae were capable of limited case repair but could not build an entire new case. Larval diet, even in the interstices, consisted chiefly of detritus and diatoms, although the proportions of each changed with seasonal availability. Larvae of H. borealis have the ability to regulate their oxygen consumption in a low oxygen environment and this also fits them for an interstitial life. Comparative biological data for other helicopsychids are presented.
Glomerular filtration rate and drinking rate in Japanese Quail, Coturnix coturnix japonica, in response to acclimation to saline water
Authors: Roberts Juliet R. , Hughes Maryanne R.
Published: January 2010

Adult Japanese Quail drinking tap water were acclimated, in four equal weekly increments, to a drinking solution of 0.2 M NaCl. Body weights and drinking rates were recorded daily throughout the acclimation period. Plasma samples were taken from birds drinking tap water; plasma and cloacal fluid samples were collected when birds were acclimated to 0.2 M NaCl. The highest concentration of NaCl solution on which most animals were able to maintain body weight was 0.15 M NaCl. Drinking rate increased or decreased as the concentration of drinking solution was raised to 0.2 M NaCl. Salt acclimation significantly increased plasma Na+, K+, and Cl− levels, although hematocrit remained unchanged. Glomerular filtration rate was significantly reduced by salt acclimation from 1.79 to 1.30 mL∙min−1.
Functional design and burst-and-coast swimming in fishes
Authors: Blake R. W.
Published: January 2010

A simple hydromechanical model is employed to determine the influence of overall body form on intermittent (burst-and-coast) swimming in fish. The optimum fineness ratio with respect to maximizing the distance covered per burst-and-coast cycle for given volume, mass, initial, and final velocities is about 5. Frequent burst-and-coast swimmers (e.g., Gadidae, Clupeidae) are characterized by fineness ratios of 4.0–6.5. Forms of low fineness ratio (< 2, e.g., Tetraodontidae, Diodontidae) do not swim in the burst-and-coast mode. The current view that fish are optimally designed for either high steady or unsteady swimming performance is questioned. It is suggested that the body form of many pelagic and nektonic fishes reflects a compromise appropriate for good burst-and-coast swimming performance.
Macrobenthic density, biomass, and fauna of intertidal and subtidal sand in a Magdalen Islands lagoon, Gulf of St. Lawrence
Authors: Bourget Edwin , Messier Danielle
Published: January 2010

A survey of intertidal and subtidal macrofauna (>0.5 mm) was made of a sandy bottom lagoon on the Magdalen Islands, Gulf of St. Lawrence, in June 1975. Intertidal densities averaged 11 223.8 individuals∙m−2 and biomass 8.8 g∙m−2 while subtidal densities averaged 3398.1 individuals∙m−2 and the biomass 6.4 g∙m−2. Bivalves, polychaetes, gastropods, and crustacea constituted the bulk of the fauna. In the intertidal zone, the biomass was dominated by the bivalves, but in the subtidal region the polychaetes were the dominant group. Numbers and weights were highest in the lower half of the intertidal zone and lowest in its upper half and in deeper water. Compared with other intertidal and subtidal communities from the eastern coast of North America, species richness, density, and biomass in the study area were low. Estimates of productivity were roughly comparable with those reported from the coasts of Britain, Florida, Aldabra Atoll, and the northwest Mediterranean, but they were probably much smaller than those expected from the biomass measurements reported for the New England coast and from Prince Edward Island in the Gulf of St. Lawrence.
Dispersal of the collembolan, Folsomia Candida Willem, as a function of age
Authors: Johnson D. L. , Wellington W. G.
Published: January 2010

The tendency of Folsomia Candida to disperse varies with age. In laboratory experiments, the youngest individuals rarely moved from the release sites in dispersal trays, while the older F. Candida showed a tendency to move into more distant areas. Distance travelled is an approximately linear function of body length, and length is a power function of age in this species. The same linear relationship between dispersal and age was apparent over short (2 h) and long (24 h) dispersal periods. When food was present on the release site, the dispersive behavior of the youngest and the oldest classes was unchanged. However, the presence of food restricted travel of medium-sized springtails, many of which remained in the release site to feed. Since these young adults begin oviposition while still growing at a relatively high rate, their food requirements are higher than younger and older springtails. This change in behavior significantly altered the relationship between size and distance travelled. In natural situations, it is advantageous for the youngest individuals to remain in the area in which they hatched, where ample food and moisture are likely to be found. Because of their greater tendency to disperse, the older individuals spread their eggs over a larger area.
Annual profiles of blood packed cell volumes of captive American kestrels
Authors: Rehder Nancy B. , Bird David M.
Published: January 2010

Mean hematocrits of 20 pairs of captive American kestrels (Falco sparverius) sampled from November 1980 to September 1981 fell significantly (p < 0.0001) from winter maxima of 47.9% for females and 50.9% for males to summer minima of 29.1% for females and 30.1% for males. It is suggested that ambient temperature, reproduction, and molt influence the photoperiodic control of avian hematocrit. Mean hematocrits declined 1–2 months before the onset of molt or egg laying (whichever came first for females) and increased at the termination of molt for nonlaying females only. During nonreproductive and nonmolting states, hematocrits varied indirectly and logarithmically with air temperature (r2♂+♀ = 0.74) and directly and linearly with body weight (r2♂ = 0.91, r2♀ = 0.95). Total mean packed cell volumes of males and females were not significantly different.
Étude cytophysiologique de l'épithélium intestinal du poisson-chat (Ameiurus nebulosus L.)
Authors: Noaillac-Depeyre Jacqueline , Gas Nicole
Published: January 2010

The ultrastructure of the intestinal epithelium was studied in the catfish (Ameiurus nebulosus L.) and four morphofunctional sections were recognized. The proximal segment that adjoins the stomach is involved in the absorption of alimentary lipids; these nutrients are present in absorptive cells as two different kinds of fat globules: a particulate form, which is the "exportation" form, and a reserve form. The enterocytes of the middle segment possess the ultrastructural differentiations typical of cells involved in the absorpiton of macromolecules: numerous pinocytotic figures, a tubulovesicular network, and absorptive vacuoles. The introduction into the intestinal lumen of exogenic macromolecules (horseradish peroxidase, ferritin, glycogen) indicated that these cells are capable of ingesting protein and polysaccharid macromolecules. The two terminal intestinal segments (distal and preanal) do not seem very much involved in the absorption of food. The epithelium of the preanal segment contains only one type of cell which is involved in the synthesis of mucopolysaccharid-like material.[Journal translation]
Acid–base balance, ionic status, and renal function in resting and acid-exposed white suckers (Catostomus commersoni)
Authors: Hōbe Helve , Wilkes Peter R. H. , Walker Richard L. , Wood Chris M. , McMahon Brian R.
Published: January 2010

Renal function was investigated in the stenohaline Catostomus commersoni held at water pH 7.3 for 5 days. Urine displayed remarkably low levels of Na+, Cl−, K+, Ca2+, and Mg2+ and was very acidic (mean pH 6.5). Renal electrolyte conservation was characterized by almost complete reabsorption of NaCl and to a lesser degree, K+, Ca2+, and Mg2+. Net H+ excretion was + 11.2 μequiv∙kg−1∙h−1, resulting primarily from a high titratable acid content. The physiological consequences of exposure to ambient pH 4.3 for 4 days included disturbances in plasma acid–base status with relatively minor changes in both plasma ion levels and renal output (E). A mixed metabolic and respiratory acidosis developed, which was not compensated for by increased renal H+ excretion. Both plasma NaCl levels and ENa+ decreased but ECl− remained unchanged. EK+ was correlated with plasma hyperkalemia. No changes in plasma levels or excretion of Ca2+ or Mg2+ occurred. These findings provide some physiological evidence supporting the contention that suckers are relatively acid tolerant. It is suggested that the copious amounts of mucus covering their gills may have served a protective role by retarding proton entry and limiting branchial ion loss.
Effect of retinoic acid on limb regeneration in Xenopus laevis
Authors: Scadding Steven R.
Published: January 2010

The objective of this experiment was to determine the effect of retinoic acid on the process of limb regeneration in the African clawed frog, Xenopus laevis. Limbs were bilaterally amputated through the radio-ulna and then treated for 15 days with retinoic acid in the aquarium water, at 3, 15, or 75 IU/mL. The retinoic acid inhibited limb regeneration in a dose-dependent manner, reduced the length of the regenerates, and produced irregularities in the morphogenesis of the cartilage rod in the regenerate. The regenerated limbs were removed after 150 days by amputation through the humerus, and the limbs were again allowed to regenerate. In the retinoic acid treated animals, despite the fact that retinoic acid treatment had been discontinued over 4 months previously, limb regeneration was still inhibited. These results suggest that retinoic acid has a long-term effect on the treated animals.
Heterotypic cell contacts and basal lamina morphology during hair follicle development in the mouse: a light, scanning, and electron microscopic study at the site of tissue interaction
Authors: Goldberg E. A. , Hardy M. H.
Published: January 2010

A study was made of the interface between the epithelial hair matrix and the mesenchymal dermal papilla in developing vibrissa follicles in the mouse. The objective was to examine the hypothesis that the instruction from the dermal papilla mesenchyme, which is known to lead to differentiation of the hair matrix cells into inner root sheath and hair, is mediated by heterotypic cell contacts. The upper lip skin of 14.0- to 15.5-day embryos was separated into epithelium and mesenchyme after ethylene diamine tetraacetic acid or trypsin treatment, and sometimes tape-stripped or cryofractured before scanning electron microscopy. All methods were compared and evaluated. The chelating agent produced clean preparations of intact basal lamina on mesenchyme, proving its usefulness for complex interfaces. Transmission electron microscopy of untreated and of separated tissue confirmed that gaps appeared only in the previously intact lamina densa surrounding the dermal papilla and persisted for three stages of follicle development. Mesenchymal cell processes from the papilla were found in close contact with epithelial hair matrix cells through these gaps just prior to and during differentiation of the hair matrix cells, but not at earlier stages. These contacts could therefore be involved in transmission of the instruction.
Development of Sarcocystis in mule deer transmitted through dogs and coyotes
Authors: Dubey J. P. , Kistner T. P. , Callis Gayle
Published: January 2010

Tissues from 13 experimentally inoculated mule deer (Odocoileus hemionus) from Oregon, studied by G. Hudkins and T. P. Kistner in 1976 and L. D. Koller, T. P. Kistner, and G. Hudkins in 1977, were reexamined. The following additional information on Sarcocystis hemionilatrantis was obtained. Two types of meronts were found in deer necropsied between 29 and 41 days postinoculation (DPI). Type 1 meronts were in capillaries in adrenal glands, kidney, lymph node, lung, choroid plexi, and spleen; meronts were 20.5 × 13.5 μm (14−32 × 10−20 μm; n = 26) and contained 20 to 35 nuclei. Type 2 meronts were found in macrophages in muscular tissues; these meronts were 20 × 14 μm (10−35 × 7−19 μm; n = 7) and contained 10 to 60 merozoites. Sarcocysts were seen in three deer at 63, 65, and 90 DPI. At 63 and 65 DPI sarcocysts were immature and their walls were thin (< 1 μm) and smooth. At 90 DPI, sarcocysts were up to 525 μm long and 50 μm wide; the sarcocyst wall was 1 to 2 μm thick and cross striated. In the same deer another type of mature sarcocyst was also seen; sarcocysts were up to 825 μm long, the walls were 2 to 4 μm thick and lacked cross striations. Two additional 3-day-old deer were inoculated orally with sporocysts from the feces of a dog fed meat from a mule deer from Montana naturally infected with Sarcocystis sp. Deer No. 1, fed 107 sporocysts, was killed at 14 DPI and deer No. 2, fed 5 × 106 sporocysts, was killed at 24 DPI. At 14 DPI, meronts were found in capillaries and arteries in the lung, heart, and spleen; the meronts were 26.5 × 20 μm (14−39 × 14−25 μm; n = 31) and contained up to 100 nuclei. At 24 DPI, intravascular meronts were found in the spinal cord, hepatic lymph node, kidney, thyroid gland, and mesenteric lymph node. In addition, meronts were found in macrophages in muscular tissues; these meronts were 16 × 10 μm (10−28 × 7−14 μm; n = 10) and contained up to 40 nuclei.
ON INTERSECTING A SET OF ISOTHETIC LINE SEGMENTS WITH A CONVEX POLYGON OF MINIMUM AREA
Authors: MUKHOPADHYAY ASISH , GREENE EUGENE , RAO S. V.
Published: January 2010

We describe an O(n2)-time algorithm for computing a minimum-area convex polygon that intersects a set of n isothetic line segments.
InSAR mapping and modelling of an active Iranian salt extrusion
Authors: Aftabi Pedram , Roustaie Mahasa , Alsop G.Ian , Talbot Christopher J.
Published: January 2010

Interferometric synthetic aperture radar (InSAR) imaging is a powerful technique that is increasingly used to extract detailed 3D information on Earth surface structures, including exposed diapiric surfaces. We have used InSAR to map, for the first time, the cumulative surface deformation in a 6 km × 6 km region surrounding an active salt diapir (Syahoo) and its associated surface salt flow (or namakier) exposed in the Zagros Mountains of southern Iran. Images provided by the European Space Agency were acquired in 12 increments (ranging in length between 35 and 1248 days) over a 14 year interval between July 1992 and May 2006. The deformation of the salt surface is non-steady, with (extrapolated) rates of displacement varying between surficial uplifts of +1.4 mm day
−1
(+511 mm a
−1
) and subsidence of −2.2 mm day
−1
(−803 mm a
−1
). Growth of a central topographic dome occurs following short wet intervals to create a salt fountain morphology, which then slowly decays during the intervening long dry periods. Salt associated with dynamic ‘bulging' of the central dome during wet intervals may flow laterally via gravity spreading into the surrounding salt sheet, resulting in deflation and subsidence of the dome, which is counteracted by growth and inflation of the adjacent namakiers. Salt ‘bulges' that migrate down the namakier, resulting in local inflationary and deflationary cycles of the surface, may be regarded as episodic pulses of gravity spreading. Areas of inflation and deflation are also observed to commonly reverse during dry to wet periods, as the overall salt system effectively self regulates as it continually strives for dynamic equilibrium. As long as the source of salt remains undepleted, gravity spreading of the dome ultimately results in more buoyancy-driven salt flowing up the diapiric neck to replenish and feed the extrusion and maintain the gross fountain morphology.
New time constraints on lithospheric-scale oroclinal bending of the Ibero-Armorican Arc: a palaeomagnetic study of earliest Permian rocks from Iberia
Authors: Weil Arlo , Gutiérrez-alonso Gabriel , Conan Jordan
Published: January 2010

The Palaeozoic Variscan orogeny was a large-scale collisional event that involved amalgamation of multiple continents and microcontinents. Previous palaeomagnetic and structural analyses of the western Variscan orogen, notably the Ibero-Armorican Arc, suggest that this region underwent oroclinal bending of an originally near-linear orogen during the latest stages of Variscan deformation in the late Palaeozoic. These analyses necessitate a two-stage tectonic history with east–west compression forming a linear belt in the Carboniferous, followed by a change in regional compression directions resulting in crustal block rotation and formation of the present-day arc. This study presents new palaeomagnetic analyses of Early Permian samples from the Sotres and Cabranes formations (41.3°N, 222.5°W, α95= 13.1°) in the northern inner limb and the Viar Basin (51.8°N, 199.2°W, α95= 6.7°) in the southern outer limb of the arc. Both locations yield expected Early Permian palaeomagnetic pole positions for stable Iberia, implying that measured magnetizations have undergone no significant vertical-axis rotation since acquisition, and thus were acquired subsequent to oroclinal bending. This new result places a time constraint of about 10 Ma for oroclinal bending of the Ibero-Armorican Arc, which agrees well with recent geodynamical models that relate oroclinal bending to lithospheric delamination in this region.
Magnetotelluric characterization of a salt diapir: a case study on Bicorb–Quesa Diapir (Prebetic Zone, SE Spain)
Authors: Rubinat M. , Ledo J. , Roca E. , Rosell O. , Queralt P.
Published: January 2010

The availability of geophysical data to determine the geometry at depth of a salt diapir and its surrounding structure is essential because of the complexity and changing geometry of these structures. For this purpose, potential field methods are commonly the first steps in subsurface exploration whereas seismic techniques are applied in later stages. However, the magnetotelluric method (MT) may fill the gap between the precision and the time that these two methods entail. To prove the usefulness of the MT method, it has been applied to the Bicorb–Quesa Diapir. This diapir is composed of evaporitic rocks piercing an overburden of carbonate rocks, providing a wide and contrasting range of electrical resistivity values. In this situation, the MT method may provide a coherent and realistic image of the subsurface. The application of the MT method has allowed us to (1) recognize a basement fault with a vertical throw of 1000 m, (2) elucidate the shape of the diapir, which is asymmetrical, with a north wall vertical and south wall dipping southwards, and (3) determine that all of the Late Triassic salt is concentrated in the diapir core.

Supplementary material:

Original curves and the model adjustments are available at
http://www.geolsoc.org.uk/SUP18386
.
Anatomy, age and evolution of a collisional mountain belt: the Baltoro granite batholith and Karakoram Metamorphic Complex, Pakistani Karakoram
Authors: Searle M.P. , Parrish R.R. , Thow A.V. , Noble S.R. , Phillips R.J. , Waters D.J.
Published: January 2010

Geological mapping and U–(Th)–Pb geochronology from the Karakoram Metamorphic Complex and Baltoro granite batholith has resulted in more detailed timing constraints on tectonic evolution of Asian crust. During and following collision and accretion of the Kohistan Arc and the Indian plate to the southern margin of Asia, crustal thickening along the Karakoram resulted in polyphase deformation, metamorphism and melting. U–Pb zircon and monazite ages show that kyanite- and sillimanite-grade metamorphism in the Baltoro region peaked during Oligocene–Early Miocene (
c
. 28–22 Ma) times. At structurally deeper levels sillimanite-grade migmatites of the Dassu dome have Pliocene (
c
. 5.4–3.5 Ma) ages. New U–Pb ages from crustal melt biotite + muscovite + garnet leucogranites from the Trango Towers, Cathedral peak and Paiyu peak across the Baltoro batholith range from 19.8 ± 0.5 Ma to perhaps as young as 14 Ma. Using data from both the Hunza and Baltoro regions we suggest that regional high-grade metamorphism was diachronous in space and time and could have lasted continuously for at least 37 Ma (
c
. 50–13 Ma) or as much as 50 Ma (
c
. 63–13 Ma) along the southern margin of the Asian plate in the Karakoram. Crustal melting along the Baltoro granite batholith spanned at least 13 Ma (26.4–13 Ma).

Supplementary material:

Analytical methods and description of U–(Th)–Pb data of samples are available at
http://www.geolsoc.org.uk/SUP18382
.
High-resolution dynamics of Early Jurassic marine extinctions: the case of Pliensbachian–Toarcian ammonites (Cephalopoda)
Authors: Dera Guillaume , Neige Pascal , Dommergues Jean-Louis , Fara Emmanuel , Laffont Rémi , Pellenard Pierre
Published: January 2010

The Pliensbachian–Toarcian interval was marked by major environmental disturbances and by a second-order mass extinction. Here, we reappraise the taxonomic, spatiotemporal and selective dynamics of extinctions over the whole interval, by analysing a high-resolution dataset of 772 ammonite species from NW Tethyan and Arctic domains. On average, 40–65% of ammonite species disappeared during each subchronozone, but higher extinction pulses (reaching 70–90%) prevailed from the Margaritatus to the Dispansum Chronozone. The main extinctions, corresponding to the Gibbosus, Pliensbachian–Toarcian boundary, Semicelatum, Bifrons–Variabilis, and Dispansum events, differed in their dynamics, suggesting episodes of ecological stress related to climate change, regression, disturbance in the carbon cycle or anoxia. The multi-pulsed volcanic activity in the Karoo–Ferrar province could well have triggered these ecological changes. In addition, ammonites experienced a morphological bottleneck during the Gibbosus event, 1 Ma before the Early Toarcian diversity collapse. Typically, drops in richness were related both to high extinctions and to declines in origination rates. This feature could result from strengthened ecological stresses related to the temporal overlap of environmental disturbances. After the Early Toarcian crisis, the recovery of ammonites was rapid (2 Ma) and probably influenced by a coeval marine transgression.

Supplementary material:

Figures showing a comparison of extinction and origination patterns based on different datasets, and variations of the morphospace occupation are available at
http://www.geolsoc.org.uk/SUP18381
.
Slip on Superhydrophobic Surfaces
Authors: Rothstein Jonathan P.
Published: January 2010

This review discusses the use of the combination of surface roughness and hydrophobicity for engineering large slip at the fluid-solid interface. These superhydrophobic surfaces were initially inspired by the unique water-repellent properties of the lotus leaf and can be employed to produce drag reduction in both laminar and turbulent flows, enhance mixing in laminar flows, and amplify diffusion-osmotic flows. We review the current state of experiments, simulations, and theory of flow past superhydrophobic surfaces. In addition, the designs and limitations of these surfaces are discussed, with an eye toward implementing these surfaces in a wide range of applications.
Wave–Vortex Interactions in Fluids and Superfluids
Authors: Bühler Oliver
Published: January 2010

This article reviews the methods of wave–mean interaction theory for classical fluid dynamics, and for geophysical fluid dynamics in particular, providing a few examples for illustration. It attempts to bring the relevant equations into their simplest possible form, which highlights the organizing role of the circulation theorem in the theory. This is juxtaposed with a simple account of superfluid dynamics and the attendant wave–vortex interactions as they arise in the nonlinear Schrödinger equation. Here the fundamental physical situation is more complex than in the geophysical case, and the current mathematical understanding is more tentative. Classical interaction theory might be put to good use in the theoretical and numerical study of quantum fluid dynamics.