bluuebunny/crossref_metadata_2025 huggingface dataset:
Eggshell structure in the Shoebill and pelecaniform birds: comparison with Hamerkop, herons, ibises, and storks
Authors: Mikhailov Konstantin E.
Published: July 2008

Scanning electron microscope investigation of eggshell structure supports earlier beliefs that the pelecaniform family assemblage is a natural group. All families of pelecaniform birds except the Phaethontidae show complete similarity in the structure of both the crystallized eggshell and the accessory (amorphous) material (cuticle and cover) located in the outer surface of the shell. Comparisons with other avian taxa (93 families of non-passeriform birds) show that in terms of eggshell structure, Scopus umbretta is an "advanced" ardeid and Balaeniceps rex a rather unusual pelecaniform. All these birds should form one large group with the Ardeidae and clearly distinguished from the Ciconiidae. The results of this investigation imply that, ultimately, the deposition of microglobular material in the cover of avian eggshell is subject to phylogenetic constraints rather than having an adaptive (ecological) cause.
"Strains" and the classical biological control of insect pests
Authors: Clarke A. R. , Walter G. H.
Published: July 2008

The classical biological control technique of introducing two or more populations of the same species of beneficial agent to increase the genetic diversity of that species (and so increase the chances of achieving a successful project) is reviewed. From standard literature sources, all cases of multiple introductions of conspecific populations against insect targets were listed and the effect of subsequent introductions on the outcome of the project was recorded. Of 178 projects identified, involving 417 separate importations, only 11 (6.2%) were successful through a second or later importation of the same morphologically defined species of beneficial agent. Of these, five involved host-related "strains" that are likely to be cryptic species, so the success rate for the introduction of conspecific populations falls to 3.4%. The possibility that some (or even all) of the other six cases also involved cryptic species awaits investigation. Our analysis demonstrates that introducing two or more populations of the same species is less likely to result in enhanced success than if other species of natural enemies are sought for "normal" classical biological control (historical success rate 12–16%). In our discussion we focus on the genetic theory of species which underpins this area of applied biology and find that there is also no theoretical support for the continued introduction of strains.
Reproductive energetics of adult male yellow-bellied marmots (Marmota flaviventris)
Authors: Salsbury Carmen M. , Armitage Kenneth B.
Published: July 2008

We examined the energy expenditure of adult male yellow-bellied marmots (Marmota flaviventris) and its relationship to various female-defense characteristics critical to male reproductive success. Resting metabolic rates of males were estimated in the laboratory via oxygen-consumption analysis, and field metabolic rates were estimated using a doubly labeled water technique. Male home-range size, number of females defended by males, dispersion of females in the habitat, and date into the active season were considered to be predictors of male energy expenditure in excess of maintenance costs (field metabolic rate minus resting metabolic rate). Energy expenditure was best explained by a defensibility index based on the number and dispersion of females defended; expenditure increased with number and dispersion of females. Energy expenditure increased with date into the active season. Environmental constraints on male activity during the mating season may have led to a shift in male reproductive investment to later in the season, when intruder pressure by conspecifics increased. No short-term survival costs were associated with high energy expenditure; males appeared to engage in reproductive behaviors congruent with their physiological capabilities.
Diet of harp seals (Phoca groenlandica) in nearshore waters of the northwest Atlantic during 1990 – 1993
Authors: Lawson John W. , Stenson Garry B. , McKinnon Dave G.
Published: July 2008

The nearshore diet of northwest Atlantic harp seals (Phoca groenlandica) was determined by reconstructing the contents of 1167 prey-containing stomachs (78.3% of 1490) collected from 1990 to 1993. Although harp seals consumed at least 62 species, 6 accounted for most of the mass consumed and their relative importance varied by area. Based on percent wet mass, sculpins (Cottidae) and Arctic cod (Boreogadus saida) were the main components of the diet of older seals (> 1 year old) off Labrador, whereas Arctic cod and Atlantic herring (Clupea harengus) were the main prey of seals from northeastern Newfoundland. A more diverse diet was observed in seals taken off the west coast of Newfoundland, where capelin (Mallotus villosus), herring, Atlantic cod (Gadus morhua), redfish (Sebastes spp.), and Arctic cod were the main species. Redfish and Atlantic cod were important to seals along the south coast of Newfoundland. Eighty percent of fish consumed were less than 18 cm long, smaller than those taken by commercial fisheries. Pups (less than 1 year old) consumed fewer and smaller prey of a less varied assortment. Annual and seasonal variation in the diets was observed in the collection from northeastern Newfoundland. Arctic cod was the major prey consumed throughout the year by seals of all ages, although the relative importance of herring, capelin, and squid (Teuthoidea) increased during the summer. Invertebrates and capelin made up a greater proportion of the diet in 1992, owing to a decline in consumption of Arctic cod. This finding was associated with a decrease in the mass of stomach contents. Diet diversity did not change significantly over the study period.
Spacing patterns of ermine, Mustela erminea L., in a Quebec agrosystem
Authors: Raymond Michel , Robitaille Jean-François
Published: July 2008

Spacing patterns in mammals are influenced by mating systems such as polygyny–promiscuity. Movement parameters were monitored over 3 years in an increasing population of ermine, Mustela erminea cicognanii, in southern Quebec (45°22′N, 71°51′W), and the effects of age, sex, breeding status, and annual densities on movements were examined. Residency times (range 24–443 d) were significantly higher in females than in males. Populations were composed of more visiting males than residents and more resident females than visiting females. Adult and juvenile males travelled significantly more than adult females and during the year of highest density than in other years. Males' travel distances significantly decreased and those of females increased during the postbreeding season. Males' home range sizes (range 1.0–87.4 ha) were significantly larger than those of females during the postbreeding period and over the whole season. Home ranges overlapped only between the sexes. Our study showed little influence of annual variations in population density on spacing patterns. We conclude that (i) movements in Nearctic ermine populations are, at moderate to high population levels, influenced by intraspecific characteristics, and (ii) in view of the similar behavior of Palaearctic and Nearctic ermine, interdemic body size range has little influence on spacing patterns of ermine.
Competitive interactions for foraging microhabitats in a size-structured interspecific dominance hierarchy of two sympatric stream salmonids in a natural habitat
Authors: Nakano Shigeru
Published: July 2008

Aggressive interactions, foraging behaviour, microhabitats, and growth of individuals of two sympatric stream-dwelling salmonids, white-spotted charr (Salvelinus leucomaenis) and masu salmon (Oncorhynchus masou masou), were studied in a mountain stream in central Japan. The fishes within a single pool in the stream formed an interspecific size-structured dominance hierarchy. Dominant individuals of both species maintained foraging territories against both subordinate conspecifics and heterospecifics, whereas subordinate charr adopted nonterritorial tactics. In each species, the most dominant fish usually held the focal point nearest to the pool inlet, which ensured priority of access to drifting food, with subordinates distributed farther downstream. Foraging microhabitats differed vertically in the water column between the two species, charr utilizing a home range near the stream bed and salmon occupying the midlayer. The frequency of foraging attempts by salmon was considerably higher than that by charr. Although daily body mass increments of dominant individuals were significantly larger than those of conspecific subordinates in each species, those of some subordinate salmon exceeded those of dominant charr.
Prey selection by insectivorous bats: are essential fatty acids important?
Authors: Schalk Gina , Brigham R. Mark
Published: July 2008

Although body temperatures of torpid animals fall well below the melting point of many fats, body fats must remain fluid to be metabolized. High levels of dietary essential fatty acids (EFAs) may facilitate the use of torpor, as an increase in the proportion of EFAs in body fat decreases the melting point of body fats. The purpose of our study was to determine the importance of EFAs in the diets of four reproductive classes (males and nonreproductive pregnant, and lactating females) of three species of insectivorous bats: Myotis yumanensis, M. lucifugus, and M. californicus. Males are expected to use torpor frequently and, therefore, should select a diet high in EFAs. We ranked insect orders found in bat feces (diet) and light-suction-trap samples (availability) on the basis of their linoleic acid (a common EFA) content. We used these ranks to obtain estimates of the linoleic acid content of bats' diets, i.e., "dietary fat scores," and of available insects' "trap sample fat scores," respectively. Dietary fat scores did not differ significantly among reproductive classes. As predicted, the average fat score of males was high relative to the fat score of available insects. However, fat scores of male M. lucifugus and M. yumanensis were significantly greater than those of male M. californicus. Thus, EFAs do not appear to be as important in the diet of the latter species, suggesting that torpor may not be employed regularly.
Changes in fish populations affected by the construction of the La Grande complex (Phase I), James Bay region, Quebec
Authors: DesLandes Jean-Claude , Guénette Sylvie , Prairie Yves , Fortin Réjean , Roy Dominique , Verdon Richard
Published: July 2008

Catches per unit of effort (CPUE) with experimental gill nets, recruitment, growth, and condition were monitored between 1977 and 1992 to evaluate the impact of impoundment on the main fish species of La Grande 2, Opinaca, and Caniapiscau reservoirs and the Boyd–Sakami diversion. CPUE and recruitment of northern pike (Esox lucius) and lake whitefish (Coregonus clupeaformis) increased markedly at most stations after impoundment and decreased at the end of the series. The lake whitefish and cisco (Coregonus artedii) showed their most striking rise in CPUE at two bay stations of La Grande 2 and Opinaca reservoirs. CPUE and recruitment of the longnose sucker (Catostomus catostomus), white sucker (Catostomus commersoni), and lake trout (Salvelinus namaycush) (Caniapiscau) showed a general decrease following impoundment. CPUE for the walleye (Stizostedion vitreum) also decreased at several stations; however, the two most southerly stations in La Grande 2 reservoir and the Boyd–Sakami station showed high CPUE during the series. Concentration–redistribution phenomena explain part of the observed variations in CPUE. Correlation analyses showed that walleyes and white suckers were attracted to the warmer, more turbid stations, and that the high primary and secondary productivity of bay stations attracted the coregonines. Growth and condition of the main species increased during variable time intervals after impoundment and decreased at the end of the series.
Vasoactivity of the coronary artery of rainbow trout, steelhead trout, and dogfish: lack of support for non-prostanoid endothelium-derived relaxation factors
Authors: Farrell A. P. , Johansen J. A.
Published: July 2008

This study surveyed and compared vasoactive responses of isolated coronary vessels from steelhead trout (Oncorhynchus mykiss), rainbow trout (also O. mykiss), and spiny dogfish (Squalus acanthias). The purpose of the investigation was twofold: to identify vasoactive controls that were possibly mediated by the vascular endothelium and to highlight the possible consequences on vasoactivity of the coronary lesions known to be present in the main coronary of salmonids but not dogfish. The test substances included acetylcholine, adenosine, adenosine triphosphate, adenosine diphosphate, serotonin, thrombin, bradykinin, prostaglandin F2α, prostaglandin I2, prostaglandin E2, and the fatty acids arachidonic acid, docosahexaenoic acid, and eicosapentaenoic acid. Acetylcholine, adenosine, adenosine triphosphate, adenosine diphosphate and prostaglandin F2αtypically produced contractions. Use of endothelial removal techniques and antagonists failed to reveal any relaxations that might involve the endothelium. Thrombin and bradykinin had no vasoactivity. Serotonin, prostaglandin I2, and prostaglandin E2produced relaxations that were not mediated by the endothelium. The powerful relaxations observed with prostaglandin I2and prostaglandin E2and the powerful contractions observed with prostaglandin F2αsuggest a major role of prostanoids in coronary vasoactivity in fish. These prostanoid-mediated mechanisms, in addition to the previously demonstrated powerful contractions with endothelin-1, point to an important role for the endothelium. No major qualitative or quantitative differences in vasoactivity could be related to differences in coronary lesion severity.
Ecology of the lizard Norops oxylophus (Polychrotidae) in lowland forest of southeastern Nicaragua
Authors: Vitt Laurie J. , Zani Peter A. , Durtsche Richard D.
Published: July 2008

The lizard Norops oxylophus used a variety of microhabitats distributed linearly along streams in southeastern Nicaragua. Body temperatures averaged 27.8 °C and lizards typically were in shade. Lizards spent 98.16% of their time stationary and 1.84% moving. The rate of movement was low (0.001 m∙s−1) even when corrected for time not moving (0.071 m∙s−1). Caterpillars, spiders, ants, and various orthopterans composed most of the diet. Prey size was only weakly correlated with lizard snout–vent length (SVL) and there was no sexual difference in prey size independent of SVL. Lizards averaged 0.01 prey attacks/min and most lizards spent less than 0.15% of their time feeding. Males were larger than females, but females had a relatively larger body and greater mass. Females reach sexual maturity at 49 mm SVL and produce clutches of a single egg in rapid succession. Males reach sexual maturity at 53 mm SVL. Many ecological characteristics of N. oxylophus reflect a set of characteristics evolving early in the N. fuscoauratus series of the anoline lineage that has contributed to their ecological success in stream habitats of Caribbean lowland forest.
Pelage cycle and hair bundle structure in the young and adult ferret, Mustela putorius
Authors: Blomstedt Leena
Published: July 2008

The pelage growth cycle and hair bundle structure of three male ferrets, Mustela putorius, as young animals and adults were examined histologically. The follow-up period was 17 months. The growth phase of guard hairs and underfur hairs in follicular bundles was analyzed. Skin samples from the hip were prepared for light microscopy; paraffin sections were cut parallel to the skin surface and stained with a modified SACPIC method. Guard hairs started to develop earlier than underfur hairs. Young ferrets shed hairs between August and mid-November, the guard hairs in three waves and the underfur hairs in one period. In the adult ferrets, guard hair growth peaked three times between June and October. There were individual differences in the summer underfur: growth occurred in one period or in two separate waves. Moulting of the summer coat ended late in October, coinciding with the maximum number of growing winter underfur hairs. In the winter pelage the two hair types matured simultaneously. There was a guard hair in all mature winter coat hair bundles. In addition, all hairs had a medulla.
Quantitative comparisons of the morphology and ultrastructure of erythrocyte nuclei from seven freshwater fish species
Authors: Jagoe Charles H. , Welter Dave A.
Published: July 2008

Chromosome number and genomic DNA content vary widely among fish species, and ploidy can vary within species. This suggests that the size, shape, and morphological features of cell nuclei may also vary. Nucleated erythrocytes of fish are an easily sampled homogeneous population of differentiated cells ideal for inter- and intra-species comparisons. We collected blood samples from largemouth bass (Micropterus salmoides), bluegill (Lepomis macrochirus), chain pickerel (Esox niger), yellow perch (Perca flavescens), mosquitofish (Gambusia holbrooki), redeye bass (Micropterus coosae), and rainbow trout (Oncorhynchus mykiss) and removed cytoplasm and nuclear membranes from blood cells. Individual nuclei were examined and measured using scanning electron microscopy and a computerized image analysis system, and inter- and intra-species differences evaluated by nested analysis of variance. Nuclear size and shape varied significantly among species. Isolated nuclei had conspicuous apertures or holes, and the number and size of these holes also varied significantly among species. Variations in nuclear size and structure within species were small compared with interspecies differences. Little is known of the ultrastructure of erythrocyte nuclei in lower vertebrates, but their structure differs considerably from that of other vertebrate non-erythroid cells, suggesting that the organization of their DNA and associated proteins may be different.
Home ranges and movements of red foxes in central Europe: stability despite environmental changes
Authors: Meia Jean-Steve , Weber Jean-Marc
Published: July 2008

Thirteen red foxes (Vulpes vulpes) were radio-tracked between September 1989 and August 1993 in the Swiss Jura mountains. Home ranges of subadult and adult resident foxes did not differ and were small (seasonal estimates 0.48–3.06 km2). A nomadic adult was also monitored; it used a significantly larger area (12.71–25.90 km2). In most cases, home range sizes did not vary seasonally and were not affected by drastic changes in food availability. That foxes maintain a constant territory size is in accordance with both the "contractor" and "obstinate" strategies. The small observed sizes suggest that after the eradication of rabies, rural areas of central Europe are very good habitats for foxes. In the absence of clumped feeding patches or constraining factors (e.g., deep snow cover), the foxes moved regularly throughout their home range, typically in a "non-oriented zigzag." The distance travelled per day seemed to be affected only by home range size (positive correlation) and occasionally, according to the individual, by weather or snow cover. On average, the foxes moved 3.9–12.0 km a day. Despite its significantly larger home range, the nomadic fox did not move more than the resident foxes; the physical characteristics of red foxes probably set a limit to the distance travelled daily.
Fluctuating asymmetry and fractal dimension of the sagittal suture as indicators of inbreeding depression in dama and dorcas gazelles
Authors: Alados Concepción L. , Escós Juan , Emlen John M.
Published: July 2008

The effects of inbreeding on the developmental instability of skulls of dorcas (Gazella dorcas) and dama (G. dama) gazelles were investigated. In total, 132 dorcas gazelle skulls and 74 dama gazelle skulls from the Estación Experimental de Zonas Aridas in Almera, Spain, were measured. The fluctuating asymmetry of 9 meristic characters, consisting of the numbers of foramina on the two sides of the skull and mandible, was calculated. Although only the foramen infraorbitalis showed a significant increase in asymmetry with inbreeding in dorcas gazelles, the sum of the foramina in 5 of the skull regions clearly indicates an increase in asymmetry with inbreeding in both dorcas and dama gazelles. The fractal dimension of the sagittal suture was calculated by means of the coastline method. A greater effect of inbreeding on the sagittal suture in dama than in dorcas gazelle was observed, in concordance with the more evident deleterious effects of inbreeding depression in dama than in dorcas gazelles.
Comparative thermal ecology of the high-altitude lizard Sceloporus grammicus on the eastern slope of the Iztaccihuatl Volcano, Puebla, Mexico
Authors: Lemos-Espinal Julio A. , Ballinger Royce E.
Published: July 2008

We studied the thermal ecology of Sceloporus grammicus occurring in very different thermal environments at 3700 and 4400 m elevation on the Iztaccihuatl Volcano, Mexico. Despite differences in the thermal environment between study sites, individual lizards maintained similar active body temperatures (around 31.5 °C). Similar body temperatures at the two study sites probably result in differences in the cost of the thermoregulatory behavior. Lizards at the high-altitude site, an open area with few predators or competitors, presumably incur a lower thermoregulatory cost than those at the low-altitude site, which has a considerable number of shaded spots and more predators and competitors. Lizards at the low-elevation site showed a greater resistance to high temperatures than those at the high-elevation site. Physiological acclimatization to higher environmental temperatures at low elevation is likely to explain the greater heat tolerance. Freezing tolerance, thermoregulatory behavior, and low energy requirements permit S. grammicus to survive at high altitudes.
Influences off predation risk and energy maximization on food selection by beavers (Castor canadensis)
Authors: Basey John M. , Jenkins Stephen H.
Published: July 2008

We developed deterministic models to generate predictions for three hypotheses: beavers (Castor canadensis) select food on the basis of (1) maximization of energy return, (2) minimization of predation risk, or (3) minimization of the ratio of predation risk to energy return. To test predictions, beavers were provided with a choice of two sets of quaking aspen, 1.5 or 3.0 cm in diameter, with the 3.0-cm stems placed at distances from the pond equal to or greater than those of the 1.5-cm stems. The models predicted that beavers using strategy 1 should select mainly large aspen, beavers using strategy 2 should select mainly small aspen, and the preferences of beavers using strategy 3 should depend on the relative distances of large and small aspen. Selection of experimental aspen by beavers was consistent with hypothesis 3. Beavers primarily stripped bark of aspen for consumption in water, and the stripping rate increased as the water temperature decreased. Size–distance relationships in selection of aspen and the stripping location of experimental aspen in relation to water temperature were consistent with the hypothesis that beavers were trading off maximization of profitability against minimization of predation risk.
The interaction between antipredator behaviour and antipredator morphology: experiments with fathead minnows and brook sticklebacks
Authors: Abrahams Mark V.
Published: July 2008

Prey species have two fundamental strategies for reducing their probability of being killed by a predator: behavioural modification and morphological defenses. It is hypothesized that prey species which possess morphological defenses should exhibit less behavioural modification in response to predation risk than species lacking such defenses. Experiments were conducted to examine behavioural modification by armoured (brook sticklebacks, Culea inconstans) and unarmoured (fathead minnows, Pimephales promelas) prey species foraging in the presence of a predator (yellow perch, Perca flavescens). Two experiments measured habitat avoidance and reactive distance to an approaching predator. The results of these experiments were consistent with the hypothesis. Compared with fathead minnows, brook sticklebacks exhibited relatively little behavioural modification in response to the presence of a predator, both in terms of avoiding dangerous areas and in their reactive distance to an approaching predator. Sticklebacks, however, graded their reactive distance to an approaching predator in relation to both their body size and group size. These data suggest that the morphology of brook sticklebacks and their behavioural sensitivity to predation risk may allow them to efficiently exploit habitats that contain predators.
Lactation, hibernation, and mass dynamics of American black bears and grizzly bears
Authors: Farley Sean D. , Robbins Charles T.
Published: July 2008

Milk composition and intake, cub growth, and mass loss of hibernating lactating and nonlactating American black bears (Ursus americanus) and grizzly bears (Ursus arctos horribilis) were investigated. Except for ash content, milk composition was similar between species. Lipid content varied only slightly throughout lactation, whereas carbohydrate content increased from 1 to 3% during hibernation before decreasing to less than 0.5% at the end of lactation. Protein and dry matter content increased from 6.6 ± 0.4 and 29.8 ± 3.9% during hibernation to 13.7 ± 1.1 and 34.4 ± 3.7% post hibernation, respectively. The ash content of black bear milk increased from 1% during hibernation to 2% after den emergence, but the ash content of grizzly bear milk (1.3 ± 0.1%) did not fluctuate. Mean milk intake and growth during hibernation were 185 ± 89 and 49 ± 9 g/day for black bear cubs and 353 ± 54 and 98 ± 22 g/day for grizzly bear cubs, respectively, which accounted for about 9% of the estimated yearly milk consumption by the cubs. Milk intake peaked during the summer at levels approximately 4 times higher than those occurring in the winter den. The mass lost by older, hibernating, nonlactating bears was proportional to their metabolic body mass and was almost exclusively lipid. The rate of mass loss by denning, lactating females relative to nonlactating bears was 45% higher for black bears and 95% higher for grizzly bears. The less costly black bear cub may be at an important competitive advantage when both species occupy nutritionally limited habitat.
Evidence for bottom-up effects in the boreal forest: Do passerine birds respond to large-scale experimental fertilization?
Authors: Folkard Nicholas F. G. , Smith James N. M.
Published: July 2008

Boreal plant communities are strongly nutrient limited, and the animals of the boreal forest may therefore experience bottom-up nutrient limitation. We conducted a 5-year experimental study of the impact of aerial nitrogen fertilization on birds of the boreal forest near Kluane Lake, southwestern Yukon, to test for such bottom-up effects. Specifically, we tested if avian abundance and species richness increased after fertilization. Variable circular-plot point counts were made to estimate bird numbers and species richness each summer from 1988 to 1992. Fertilization had no effect on abundance for the first two summers, but total abundances of the seven commonest passerine bird species increased by an average of 46% over the final 3 years. Fertilization had no effect on bird species richness. Population densities and species richness were both low at Kluane compared with patterns seen in temperate forest. Yellow-rumped warblers (Dendroica coronata), dark-eyed juncos (Junco hyemalis), and Swainson's thrushes (Catharus ustulatus) dominated the passerine community at Kluane. There was only moderate spatial and temporal variation in songbird numbers on control plots over the 5-year study period.
Internal morphology of the gill of a loricariid fish,Hypostomus plecostomus: arterio-arterial vasculature and muscle organization
Authors: Fernandes M. N. , Perna S. A.
Published: July 2008

The structural organization of the interbranchial septum of the gill arch of the air-breathing loricariid fish Hypostomus plecostomus was examined using light and electron microscopy. In the middle of the interbranchial septum, an extensive interconnection was found between the afferent primary arteries from successive and opposing primary lamellae. The blood circulates among numerous trabeculae consisting of connective tissue, smooth muscle cells, and collagen fibres. A sheet of smooth muscle cells is localized at the borders of these interconnected primary arteries and joins the cartilage rod from one primary lamella to the adjacent one on the same hemibranch. The adductor muscles are restricted to the distal end of the interbranchial septum and consist of transverse and oblique striated muscle fibres fixed to the cartilage rod from the primary lamella of opposite hemibranchs. The arrangement of these muscle fibres suggests a double movement of adduction: approximation of the tips of the primary lamellae of opposing hemibranchs and reduction of the space between adjacent primary lamellae of the same hemibranch. The action of both smooth and striated muscles reduces the interconnecting vascular septal space between the primary arteries, which may allow fine adjustment of vascular perfusion of the distal part of the filaments as an adaptation for better blood flow under hypoxic conditions.
Effects of ultraviolet radiation on life-history stages of anurans from Ontario, Canada
Authors: Grant Karen P. , Licht Lawrence E.
Published: July 2008

We tested the effects of ultraviolet-a (uv-a) and ultraviolet-b (uv-b) radiation on life-history stages of the anurans Bufo americanus, Hyla versicolor, Rana clamitans, and Rana sylvatica. No effect of uv-a was found on eggs or larvae even at exposures twice the intensity of normal outdoor levels. Only R. sylvatica was tested in the embryo stage. All embryos exposed to 30 min or more of artificially high intensity uv-b died. After exposure to artificially high intensity uv-b of 15 min or less, or at ecologically relevant levels, there was no effect on hatching success. The proportion of abnormal embryos after exposure to 10 or 15 min of artificially high intensity treatment was higher at 12 °C than at 20 °C. The jelly surrounding the ova can effectively reduce uv-b transmission through the egg mass. Of the four species tested, only larval R. clamitans showed some tolerance of artificially high uv-b levels, but development of the survivors was arrested and metamorphosis was not initiated. Ecologically relevant doses of uv-b had no effect on developmental period, duration of metamorphic climax, or mass at metamorphosis in B. americanus, H. versicolor, or R. sylvatica. Whereas all metamorphosed juvenile R. clamitans and R. sylvatica died after exposure to high-intensity uv-b, some B. americanus survived. Older B. americanus exposed for the same length of time had higher survivorship than younger animals. The role of uv radiation in presumed amphibian population declines is discussed.
Physiological consequences of filarial parasites in the frillneck lizard, Chlamydosaurus kingii, in northern Australia
Authors: Christian Keith A. , Bedford Gavin S.
Published: July 2008

Frillneck lizards (Chlamydosaurus kingii) in northern Australia are frequently infected by a mosquito-borne filarial parasite, Oswaldofilaria chlamydosauri. Two sites were studied and the parasite was found to be common at one but absent at the other. At the site where the parasite was present, larger lizards had a higher prevalence of infection. The number of microfilariae in the blood of the lizards was not related to blood hematocrit or hemoglobin concentration. An index of body condition was not related to the presence or number of microfilariae in the blood. Maximum rates of oxygen consumption were measured by running the lizards on a treadmill and neither the presence nor the number of microfilariae was significantly related to aerobic capacity. We also analyzed the blood and physiological parameters with respect to snout–vent length (as an indication of age) to test for consequences of chronic infection, but we found no significant relationships. Although only a few physiological parameters have been examined, the available evidence does not indicate any detrimental effects of the filarial worms on the lizards in this host–parasite association.
Structure and evolution of spiracular gills in pupae of net-winged midges (Nematocera; Blephariceridae). Part I.PaulianinaandEdwardsina(subfamily Edwardsininae)
Authors: Arens Werner
Published: July 2008

The pupae of Blephariceridae develop in streams and respire by means of spiracular gills. Our knowledge about the morphology of these organs is limited, and no scanning electron microscopic analyses of their fine structure have been carried out. Therefore, ca. 30 representative species from all continents and all main taxa of the Blephariceridae have been comparatively investigated with respect to their pupal gills. This first part of a series of publications on the theme deals with the ground plan of the spiracular gills in the subfamily Edwardsininae, with special attention paid to the fine structure of the plastron and atrium. For this purpose, one or two species from the three geographically isolated subpopulations of the Edwardsininae (Madagascar, South America, Australia) have been examined and compared with a pupa from the Deuterophlebiidae, the sister-group of the Blephariceridae. The results are discussed with regard to phylogeny and agree well with recent studies on the systematics of the Nematocera. The gills of the Edwardsininae have a primitive construction compared with those of the other subfamily, the Blepharicerinae, which has a worldwide distribution. The supposed functional advantages of spiracular gills and the reason for their evolution are critically considered. The findings cast some doubts on the usual interpretation that the felt inside the atrium serves as a sealant.
The role of growth hormone in the adaptability of Atlantic salmon (Salmo salar L.) to seawater: effects on the morphology of the mucosa of the middle intestine
Authors: Nonnotte L. , Boeuf G. , Nonnotte G.
Published: July 2008

Ultrastructural modifications of the middle intestine of the salmon, Salmo salar, induced by transfer to seawater have been studied in two groups of fish: the first group received sham treatment and the second was treated with ovine growth hormone (oGH). In sham-treated fish during the first 2 days in seawater, significant distension of the intercellular spaces was observed between the apical tight junction and the basement membrane. In the basal part of the enterocytes, tubular invaginations in the intercellular spaces were closely associated with mitochondria. In oGH-implanted fish, we observed no signs of modification of the ultrastructure of the mucosa. There were no dilatations of the intercellular spaces and no infoldings in the basal part of the enterocytes. After 7 days in seawater, the mucosa of the intestine of sham- and oGH-treated fish was quite similar. The effects of oGH treatment were clear, and treatment seemed to provoke "pre-adaptation" of the intestinal mucosa before exposure to high salinity to maintain the morphology of the middle intestine of Atlantic salmon abruptly transferred to seawater.
Urban Environments: Issues on the Peri-Urban Fringe
Authors: Simon David
Published: July 2008

This chapter reviews current thinking about environment-development issues in the transitional zones between distinctly urban and unambiguously rural areas, known variously as rural-urban fringes/transition zones, or peri-urban zones/areas or interfaces (PUI). Such concerns reflect the growing real-world limitations of traditional concepts of a simple rural-urban dichotomy. Moreover, recent archaeological research suggests that these phenomena may have ancient antecedents. Present-day fringes/interfaces have become intimately bound up with notions of (more) sustainable urbanization and urban development, with different issues and agendas manifested in different geohistorical zones of urbanization. Following an overview of planning issues in (post)industrial societies, the chapter addresses the complexities of changing peri-urban production and livelihood systems in the context of rapid urbanization in poorer countries, distinctive peri-urban challenges of appropriate and flexible planning and development, and the future prospects for enhanced sustainability in this most challenging category of development-environment interfaces. Possibilities for mutual learning between geohistorical regions are also raised.
Land-Change Science and Political Ecology: Similarities, Differences, and Implications for Sustainability Science
Authors: Turner B.L. , Robbins Paul
Published: July 2008

Land-change science (LCS) and political ecology (PE) have emerged as two complementary but parallel approaches of addressing human-environment dynamics for sustainability. They share common intellectual legacies, are highly interdisciplinary, and provide understanding about changes in the coupled human-environment system. Distinctions in their problem framings and explanatory perspectives, however, have accentuated their differences and masked the symmetry in much of their findings relevant for sustainability themes. Focusing on their shared interests in the human-environment interactions of land use illuminates the differences and similarities relevant to these themes. Divergence is found primarily in regard to their different foci of interests about causes and consequences of land change. Convergence is revealed in the identification of the complexity of the interactions and the importance of context in land-change outcomes and in the general consensus found in such synthesis issues as forest transitions, vulnerability, and coproduction of science and application.
Receptor-dependent prorenin activation and induction of PAI-1 expression in vascular smooth muscle cells
Authors: Zhang Jiandong , Noble Nancy A. , Border Wayne A. , Owens Rick T. , Huang Yufeng
Published: July 2008

Although elevated plasma prorenin levels are commonly found in diabetic patients and correlate with microvascular complications, the pathological role of these increases, if any, remains unclear. Prorenin/renin binding to the prorenin/renin receptor [(p)RR] enhances the efficiency of angiotensinogen cleavage by renin and unmasks prorenin catalytic activity. We asked whether plasma prorenin could be activated in local vascular tissue through receptor binding. Immunohistochemical staining showing localization of the (p)RR in the aorta to vascular smooth muscle cells (VSMCs). After cultured rat VSMCs were incubated with 10−7M inactive prorenin, cultured supernatant acquired the ability to generate ANG I from angiotensinogen, indicating that prorenin had been activated. Activated prorenin facilitated angiotensin generation in cultured VSMCs when exogenous angiotensinogen was added. Small interfering RNA (siRNA) against the (p)RR blocked this activation and subsequent angiotensin generation. Prorenin alone induced dose- and time-dependent increases in mRNA and protein for the profibrotic molecule plasminogen activator inhibitor (PAI)-1, effects that were blocked by siRNA, but not by the ANG II receptor antagonist saralasin. When inactive prorenin and angiotensinogen were incubated with cells, PAI-1 mRNA increased a striking 54-fold, 8-fold higher than the increase seen with prorenin alone. PAI-1 protein increased 2.75-fold. These effects were blocked by treatment with siRNA + saralasin. We conclude that prorenin at high concentration binds the (p)RR on VSMCs and is activated. This activation leads to increased expression of PAI-1 via ANG II-independent and -dependent mechanisms. These data provide a mechanism by which elevated prorenin levels in diabetes may contribute to the progression of fibrotic disease.
Markers of glycemic control in the mouse: comparisons of 6-h- and overnight-fasted blood glucoses to Hb A1c
Authors: Han Byoung Geun , Hao Chuan-Ming , Tchekneva Elena E. , Wang Ying-Ying , Lee Chieh Allen , Ebrahim Benyamin , Harris Raymond C. , Kern Timothy S. , Wasserman David H. , Breyer Matthew D. , Qi Zhonghua
Published: July 2008

The present studies examined the relationship between fasting blood glucose and Hb A1cin C57BL/6J, DBA/2J, and KK/HlJ mice with and without diabetes mellitus. Daily averaged blood glucose levels based on continuous glucose monitoring and effects of 6-h vs. overnight fasting on blood glucose were determined. Daily averaged blood glucose levels were highly correlated with Hb A1c, as determined with a hand-held automated device using an immunodetection method. R2values were 0.90, 0.95, and 0.99 in KK/HIJ, C57BL/6J, and DBA/2J, respectively. Six-hour fasting blood glucose correlated more closely with the level of daily averaged blood glucose and with Hb A1cthan did blood glucose following an overnight fast. To validate the immunoassay-determined Hb A1c, we also measured total glycosylated hemoglobin using boronate HPLC. Hb A1cvalues correlated well with total glycosylated hemoglobin in all three strains but were relatively lower than total glycosylated hemoglobin in diabetic DBA/2J mice. These results show that 6-h fasting glucose provides a superior index of glycemic control and correlates more closely with Hb A1cthan overnight-fasted blood glucose in these strains of mice.
Effects of hyperinsulinemia on hepatic metalloproteinases and their tissue inhibitors
Authors: Boden Guenther , Song Weiwei , Kresge Karen , Mozzoli Maria , Cheung Peter
Published: July 2008

To gain insight into the pathogenesis of hepatic fibrosis related to insulin resistance, we have examined the effects of euglycemic hyperinsulinemia on three matrix metalloproteinases (MMP-2, MMP-9, and MT1-MMP) and on two major tissue inhibitors of MMPs (TIMP-1 and TIMP-2) in liver of insulin-sensitive and insulin-resistant rats. Four hours of insulin infusion (4.8 mU·kg−1·min−1) without or with lipid-heparin infusion (to produce insulin resistance) decreased hepatic MMP-2 mRNA (by RT-PCR), pro-MMP-2, MMP-2, MMP-9, and MT1-MMP (all by Western blots) and the gelatinolytic activity of MMP-2 (by gelatin zymography) by ∼60–80%. Hyperinsulinemia (∼1.6 mmol/l) increased TIMP-1 and TIMP-2 concentrations (by ELISA) in insulin-sensitive and insulin-resistant rats. Phosphoinositide 3-kinase was activated by insulin in insulin-sensitive rats and inhibited in insulin-resistant rats. Extracellular signal-regulated kinases 1/2 (ERK1/2) were activated by insulin in insulin-sensitive rats and partially inhibited in insulin-resistant rats; c-jun NH2-terminal kinase-1 (JNK1), JNK2/3, or p38 MAPK were only activated by lipid but not by insulin. We conclude that hyperinsulinemia, whether or not associated with insulin resistance, shifts the MMP/TIMP balance toward reduction of extracellular matrix degradation and thus may promote the development of hepatic fibrosis.
Suppression of adipocyte differentiation byCordyceps militaristhrough activation of the aryl hydrocarbon receptor
Authors: Shimada Tsuyoshi , Hiramatsu Nobuhiko , Kasai Ayumi , Mukai Mai , Okamura Maro , Yao Jian , Huang Tao , Tamai Minori , Takahashi Shuhei , Nakamura Tomoyuki , Kitamura Masanori
Published: July 2008

Mycelial extracts have a wide range of biological activities that modulate functions of mammalian cells. In this report, we sought to identify antiadipogenic mycelia with the use of 3T3-L1 cells and found that the extract of Cordyceps militaris exclusively suppressed differentiation of 3T3-L1 preadipocytes into mature adipocytes without affecting cell viability. This inhibitory effect was dose dependent, reversible, and associated with 1) a decrease in lipid accumulation, 2) blunted induction of adipocyte markers including adiponectin, peroxisome proliferator-activated receptor-γ, and CCAAT/enhancer binding protein-α, and 3) sustained expression of a preadipocyte marker, monocyte chemoattractant protein-1. C. militaris also significantly decreased accumulation of lipid and hypertrophy in mature adipocytes and preserved their response to insulin (phosphorylation of Akt) during prolonged culture. Subsequent experiments revealed that C. militaris has the potential to activate the aryl hydrocarbon receptor (AhR). In 3T3-L1 cells, treatment with AhR agonists including benzo[ a]pyrene and 3-methylcholanthrene reproduced the antiadipogenic effect of C. militaris. Furthermore, dominant-negative inhibition of AhR abrogated the suppressive effect of C. militaris on adipocyte differentiation. These results suggest that C. militaris has the potential to interfere with adipocyte differentiation through activation of AhR.
Adaptations in pulsatile insulin secretion, hepatic insulin clearance, and β-cell mass to age-related insulin resistance in rats
Authors: Matveyenko Aleksey V. , Veldhuis Johannes D. , Butler Peter C.
Published: July 2008

In health insulin is secreted in discrete insulin secretory bursts from pancreatic β-cells, collectively referred to as β-cell mass. We sought to establish the relationship between β-cell mass, insulin secretory-burst mass, and hepatic insulin clearance over a range of age-related insulin sensitivity in adult rats. To address this, we used a novel rat model with chronically implanted portal vein catheters in which we recently established the parameters to permit deconvolution of portal vein insulin concentration profiles to measure insulin secretion and resolve its pulsatile components. In the present study, we examined total and pulsatile insulin secretion, insulin sensitivity, hepatic insulin clearance, and β-cell mass in 35 rats aged 2–12 mo. With aging, insulin sensitivity declined, but euglycemia was sustained by an adaptive increase in fasting and glucose-stimulated insulin secretion through the mechanism of a selective augmentation of insulin pulse mass. The latter was attributable to a closely related increase in β-cell mass ( r = 0.8, P < 0.001). Hepatic insulin clearance increased with increasing portal vein insulin pulse amplitude, damping the delivery of insulin in the systemic circulation. In consequence, the curvilinear relationship previously reported between insulin secretion and insulin sensitivity was extended to both insulin pulse mass and β-cell mass vs. insulin sensitivity. These data support a central role of adaptive changes in β-cell mass to permit appropriate insulin secretion in the setting of decreasing insulin sensitivity in the aging animal. They emphasize the cooperative role of pancreatic β-cells and the liver in regulating the secretion and delivery of insulin to the systemic circulation.