bluuebunny/crossref_metadata_2025 huggingface dataset:
Colonization of Natural Substrates by Stream Benthos
Authors: Peckarsky Barbara L.
Published: May 2008

Natural substrates in mesh cages in a Tompkins County, New York, woodland stream were colonized by benthic invertebrates for periods of 3, 6, 9, 12, 18, 24, 30, and 42 d during autumn 1980. An experiment was designed for the purpose of distinguishing seasonal phenology from site-specific temporal (nonseasonal) succession of colonizers. Subsequent to initial colonization, patterns of species dominance were analyzed to develop hypotheses on the potential for biological interactions as explanations for observed patterns of species succession. Total benthos and species richness increased significantly with duration of exposure of experimental substrates indicating the occurrence of nonseasonal succession. However, seasonal fluctuations in abiotic variables (water temperature, current, and water depth) were also shown to have significant effects on colonization. Colonization patterns were species specific; although most species showed gradual increases in numbers given longer exposure of substrates, some showed peak densities within the first few or after intermediate sampling periods, suggestive of competitive displacement of early by later colonists. Association analysis was conducted on the abundances of 19 species pairs within four functional feeding groups to determine the degree of co-occurrence in cages or concordance of colonization patterns. Negative associations were notably absent, and positive associations were common, especially among the filter-feeders and shredders. Positive associations could be interpreted as evidence for lack of ecological divergence (no competition), or potential for present competition. This study documents the existence of site-specific temporal succession of invertebrates in a temperate woodland stream, but does not resolve the question of the importance of biological interactions in determining community changes following initial colonization. Data gathered on a smaller spatial scale would be more sensitive to detecting negative species associations.
Ecophysiology and Mercury Accumulation of Rainbow Trout (Salmo gairdneri) When Exposed to Mercury in Various Concentrations of Chloride
Authors: Walczak Barbara Z. , Hammer U. Theodore , Huang P. Ming
Published: May 2008

Rainbow trout (Salmo gairdneri) mortality was 100% when exposed to HgCl2 (2–10 μg∙Hg2+∙L−1) for 14 d in a natural low chloride medium. There was no mortality if the medium contained 100, 200, or 400 mg Cl−∙L−1 or more. Accumulation of mercury was highest in kidneys (0.65–13 μg∙g−1), spleen (0.31–4.2), gills (0.46–4.15), and liver (0.53–2.1) but accumulations differed for periods of exposure (14 or 42 d) and chloride concentration in the medium (100 or 200 mg Cl−∙L−1). In rainbow trout exposed to HgCl2 for 42 d, there were significant increases in plasma sodium level at 200 mg Cl−∙L−1 and significant decreases in plasma potassium, albumin, α1-globulin, and β-globulin levels in 100 mg Cl−∙L−1. No significant changes occurred in these parameters at other chloride concentrations or in erythrocytes, hematocrit, mean corpuscular volume, white blood cell counts, or chloride plasma levels. Although chloride concentrations in the media affect mercury accumulation by different organs as well as affecting physiological functions, there appears to be no direct relationship except for reduced mortality.
Interrenal, Thyroidal, Carbohydrate, and Electrolyte Responses in Rainbow Trout (Salmo gairdneri) during Recovery from the Effects of Acidification
Authors: Brown S. B. , Evans R. E. , Hara Toshiaki J.
Published: May 2008

Exposure to acid-treated water (H2SO4, pH 4.76) for 21 d increased plasma glucose, protein, and cortisol levels and interrenal nuclear diameter and decreased plasma electrolytes (Na+, Cl−) and osmolality in immature rainbow trout (Salmo gairdneri). Plasma L-thyroxine (T4), 3,5,3′-triiodo-L-thyronine (T3), or their ratio (T4:T3) were not altered by the acid treatment. Following termination of acid exposure, return to control levels was achieved within 1 d by plasma protein, 3 d by plasma cortisol, glucose, sodium, chloride, and osmolality, and 7 d by interrenal nuclear diameter. Thus, within 1 wk the studied aspects of the plasma fluid compartment had recovered from the effects of acid exposure.
Catchability of American Lobsters (Homarus americanus) and Rock Crabs (Cancer irroratus) by Traps
Authors: Miller Robert J.
Published: May 2008

Catches per trap of lobsters (Homarus americanus) and rock crabs (Cancer irroratus) were compared to densities of each species measured by divers. Trapping and diver surveys were carried out in habitats with and without macroalgae. Catchability coefficients (catch per trap/animal density) increased greatly with animal size. For example, in a habitat with macroalgae catchabilities were 13, 47, and 492 m2∙trap−1 for lobsters of 50–59, 60–69, and 70–89 mm carapace length, respectively. For crabs of 60–79 and [Formula: see text] carapace width, catchabilities increased by factors of three or seven, depending on habitat type. Data from trap catches and diver surveys agreed that lobster, biomass was similar and size frequencies different between habitats. Trapping and diving results also agreed that crab biomass and size frequency differed between habitats.
Molecular Divergence and Evolutionary Relationships in Pontoporeia (Crustacea: Amphipoda)
Authors: Väinölä Risto , Varvio Sirkka-Liisa
Published: May 2008

To evaluate hypotheses put forward to explain the origin of the "glacial relict" faunal element in North American and Eurasian lakes, the levels of genetic divergence among species and populations of the amphipod genus Pontoporeia were studied using enzyme electrophoresis. Genetic distances among the European fresh- and brackish-water P. affinis, the North American freshwater P. hoyi, and the marine P. femorata (from Europe) ranged D = 1.5–2.8, suggesting divergence times of the order tens of million years for all these lineages. An undescribed North American coastal species (P. "affinis") was similarly distinct from P. hoyi and P. femorata, but more closely related to the European P. affinis (D = 0.5). No further systematic subdivision within these species was revealed in the examined material. The number of expressed isozyme loci was the same in P. affinis and P. femorata for all enzymes examined; the results provide no support for the hypothesis of a recent polyploidization event in the evolution of P. affinis, as earlier suspected on karyological grounds. All speculations on the role of the late Pleistocene glaciations in molding the currently recognized systematic structure of Pontoporeia were thus dismissed.
Effect of Nitrite on the Embryonic Development of Atlantic Salmon (Salmo salar)
Authors: Williams E. M. , Eddy F. B.
Published: May 2008

Effects of nitrite on eggs, alevins, and fry of Atlantic salmon (Salmo salar) were studied and of these developmental stages eggs were the most resistant with a 24-h LC50value of 3276 mg∙L−1N∙NO2. Upon hatching tolerance sharply decreased, the 24-h LC50value for early alevins (2940 mg∙L−1N∙NO2) decreasing to 121.8 mg∙L−1N∙NO2. Development in freshwater or dilute saline (10 mmol∙L−1NaCl) proceeded normally without mortalities. Long-term exposure to nitrite concentrations as low as 14 mg∙L−1N∙NO2delayed hatching and retarded embryo growth and development as well as producing cardiovascular effects such as a reduced heart rate. The physiological and environmental implications of nitrite exposure are discussed.
Effects of Fertilization and Planktivorous Fish on Epilimnetic Phosphorus and Phosphorus Sedimentation in Large Enclosures
Authors: Mazumder Asit , Taylor W. D. , McQueen D. J. , Lean D. R. S.
Published: May 2008

Enclosure experiments were conducted during 1986 and 1987 to test the hypothesis that predation-induced shifts in plankton size-structure affect epilimnetic total phosphorus (TP) through changes in sedimentation rates, both with and without external nutrient loading. Fertilization and/or planktivorous fish were applied to eight enclosures in a 2 × 2 factorial design. Epilimnetic TP was higher with fish in the unfertilized enclosures and lower with fish in the fertilized enclosures; that is, fertilization increased epilimnetic TP only in enclosures without fish, and much less than expected based on the amounts added. The fraction of TP sedimenting per unit time, and the spring to summer decline in TP, was consistently lower with fish. Sedimentation rates were poorly correlated with epilimnetic TP, but were more strongly correlated with TP decline rates and particulate phosphorus larger than 20 μm. Presence or absence of planktivorous fish can alter the trophic status of planktonic systems, and the impact of external nutrient loading by changing the size-distribution and biomass of plankton.
Stable Isotope Analysis of Carbon Flow in a Tundra River System
Authors: Bunn Stuart E. , Barton David R. , Hynes H. B. Noel , Power Geoffrey , Pope Mark A.
Published: May 2008

Stable isotope analysis was used to identify the major sources of carbon utilized by fish and aquatic invertebrates in the Koroc River, a tundra river system in northern Quebec. Juvenile arctic char (Salvelinus alpinus), together with adults and juveniles of other species of fish in freshwater, obtained their carbon from either allochthonous or autochthonous sources within the river system, via the invertebrate fauna. However, adult anadromous char caught in the river clearly derived their biomass carbon from feeding at sea. Despite the limited development of riparian vegetation throughout much of the lower river catchment, terrestrial organic matter was the most likely source of energy fueling the animal communities of small tributary streams and rapids of the mainstem Koroc. In contrast, epilithic algae made a significant contribution to food chains within Alik Lake, a deep basin along the main river channel. Aquatic mosses appeared to be of, at most, tertiary importance as a source of energy to the animal communities of the lake, despite their considerable biomass.
Biological Basis of Maturation and Spawning Waves in Pacific Herring (Clupea harengus pallasi)
Authors: Ware D. M. , Tanasichuk R. W.
Published: May 2008

Maturation rates (measured as the change in the gonosomatic index (GSI) with time) over the last month of the annual maturation cycle were estimated for male and female herring in British Columbia, between 1982–87. The data were analyzed to determine interannual and interregional differences in the maturation rate and its influence on spawning time. The data also indicated that in some areas herring spawned in discrete waves — the largest fish tended to spawn first and the smaller fish in subsequent waves. Each spawning wave lasted about 5–6 d and the interwave interval varied from 8–26 d in the Strait of Georgia. General equations were developed to describe gonadal growth over the entire maturation cycle. These equations accounted for the observed differences in: (1) the maturation rates between the sexes (males initially mature faster), (2) the interregional and interannual variation in the timing of spawning (herring tend to spawn later at higher latitudes, and earlier than normal when its warmer), and (3) provide an explanation for spawning waves. All of these phenomena derive from the fact that the instantaneous rate at which the gonad grows during the maturation cycle in both sexes depends on the weight of the fish, and the daily sea temperature.
Seasonal Development of Ice Algae and its Prediction from Environmental Factors near Resolute, N.W.T., Canada
Authors: Welch Harold E. , Bergmann Martin A.
Published: May 2008

Development of ice algae growing at the bottom of first-year congelation sea ice near Resolute, N.W.T. (75°N) was studied 1984–86. Ice algae moved downwards 1.5 cm∙d−1 as the ice thickened. Biomass increased logarithmically with doubling times on the order of 4–8 d, reaching over 150 mg chlorophyll a∙m−2 in 1985 and over 300 mg∙m−2 in 1986. Algal development was synchronous up to 120 km from the main study site. Snow cover controlled algal growth indirectly by its effect on light. Algal biomass was predictable from snow thickness and date, or snow thickness and light equally well (overall r2 = 0.77 for 1985 and 1986 combined). Ice-associated amphipods were correlated with reduced ice algal biomass, but Si and NO3 concentrations and tidal cycle had little or no detectable effect. Snow depth frequency distribution data are given. Peak ice algal biomass under low snow in 1986 was equal to 0.5 t dry weight and 4.7 kg Si∙ha−1.
Detecting Synchrony of Recruitment using Short, Autocorrelated Time Series
Authors: Thompson Keith R. , Page Fred H.
Published: May 2008

Synchrony of recruitment to distinct fish stocks is difficult to detect because the available time series are generally short and autocorrelated. The recent introduction of more sophisticated statistical techniques has not been particularly helpful; several contradictory interpretations of similar data sets are discussed in the paper. To help resolve the continuing controversy surrounding the question of synchrony, we review three statistical tests of independence and determine their power using simulated data. The tests are then applied to recruitment data for six cod (Gadus morhua) and three haddock (Melanogrammus aeglefinus) stocks of the northwest Atlantic. Prior to analysis each series was first-differenced to reduce autocorrelation and hence increase statistical reliability in the results. The cod stocks are shown to fluctuate independently of the haddock stocks. There is, however, evidence of synchrony for stocks of the same species; the more widely separated cod stocks have a lower mean correlation [Formula: see text] than the haddock [Formula: see text] but both correlations are significant at the 1% level. The within-species synchrony is not due to fluctuations in our index of egg production and it appears that environmental forcing is probably important.
Nest site selection by the fourspine stickleback, Apeltes quadracus (Mitchill)
Authors: Courtenay Simon C. , Keenleyside Miles H. A.
Published: May 2008

The fourspine stickleback, Apeltes quadracus (Mitchill), is commonly associated with aquatic vegetation on its intertidal breeding grounds, and male Apeltes build nests in the vegetation. We hypothesized that vegetation morphology is a proximate cue in Apeltes nest site selection, and that males nesting in preferred vegetation types are more successful than others in attracting females and acquiring clutches of eggs. In a laboratory experiment, one common vegetation type was rejected as a nest attachment site, but no clear preference was demonstrated among three other common and morphologically distinct types. Nests collected from these four vegetation types in the field showed that males nesting in the less preferred type had acquired fewer clutches and fewer eggs than males nesting in two of the other three types. There were no significant differences in the mean numbers of clutches or eggs acquired by males nesting in these other three types. We suggest that within fairly broad limits Apeltes is a generalist in nest site selection, and that a short breeding season in the highly variable intertidal environment may put a premium on temporal features of breeding rather than on nest location.
Gastrin immunoreactive cells in the gastrointestinal tracts from four species of fish
Authors: Reifel C. W. , Marin-Sorensen M. , Samloff I. M.
Published: May 2008

Using antiserum against human gastrin, we have demonstrated cross reactivity in endocrine cells from the gastrointestinal tracts of four fish species (Ambloplites rupestris, Lepisosteus osseus, Lepomis gibbosus, and Percaflavescens). In the corporic stomach, positive cells were found in the surface and glandular epithelium and subepithelial connective tissue of A. rupestris but only the surface and glandular epithelium of L. gibbosus whereas no immunoreactive cells were found in either L. osseus or P. flavescens. In the pylorus of A. rupestris and P. flavescens, immunoreactive cells were few in number in the surface epithelium but numerous in the underlying lamina propria. In the pylorus of L. osseus and L. gibbosus, no positive cells were seen in the lamina propria but in the former a few were present in the surface epithelium. In intestine of A. rupestris, L. gibbosus, and P. flavescens immunoreactive cells were present in both surface epithelium and subepithelial connective tissue. Possible explanations for the notable species differences are discussed.
The effect of silica aerogel on the mortality of Tribolium confusum (Duval) as a function of exposure time and food deprivation
Authors: Vrba C. H. , Arai H. P. , Nosal M.
Published: May 2008

The results of a series of tests on the efficacy of a silica aerogel, Aerosil 380, are presented. A graded response in mortality of Tribolium confusum was noted with varying exposure time (i.e., 1, 2, 3, or 5 h) to the dust. Exposure to the dust and deprivation of food accelerated the initiation of mortality and altered the shape of the cumulative mortality curves. Although some other types of insecticidal action by inert dusts (e.g., abrasion) not noted in our experiments, where adsorptivity was considered as the main mode of action, may lead to subsequent desiccation of insects and produce the type of data we have obtained, we do not believe that these mechanisms (adsorptivity, abrasion) are the sole (or major) mechanisms leading to mortality. Therefore, the fundamental question whether the insects die because of desiccation (weight loss) or whether desiccation accompanies the process of dying, remains open to further investigation.
Habitat use by spotted bats (Euderma maculatum, Chiroptera: Vespertilionidae): roosting and foraging behaviour
Authors: Leonard M. L. , Fenton M. B.
Published: May 2008

The purpose of this study was to collect data on the foraging and roosting behaviour of Euderma maculatum in the Okanagan Valley of southern British Columbia. The work was performed in the summer of 1981. Bats concentrated their foraging activity in open areas adjacent to ponderosa pine. None of the over 1000 attempted captures of prey we witnessed involved E. maculatum gleaning insects from ground or foliage, and we question the idea that big-eared bats are gleaners. Some attacks on flying insects involve steep dives to the ground, presumably in response to the defensive behaviour of prey. Spotted bats foraged alone, avoiding one another apparently by listening to the echolocation calls of conspecifics. Intrusion by one bat into the feeding area of another resulted in an altercation which stopped when one bat left the area. Heavy rain may have inhibited foraging flights, but there was no evidence that other meteorological factors or moonlight significantly inhibited foraging activity. The bats roosted alone in steep cliff faces and two radio-tagged individuals returned consistently to the same cliff face to roost. Departure was presumably influenced by light levels, as bats departed earlier on cloudy nights than on bright ones.
Erratic occurrence of anostracans in a temporary pond: colonization and extinction or adaptation to variations in annual weather?
Authors: Donald David B.
Published: May 2008

Five species of Anostraca (Branchinecta paludosa (O.F.M.), Branchinecta lindahli Packard, Eubranchipus bundyi Forbes, Eubranchipus intricatus Hartland-Rowe, and Eubranchipus ornatus Holmes) inhabited a temporary pond near Calgary, Alberta. During a 14-year study of this pond, occurrence and species composition of anostracans changed almost every year. In most years only one to three species were common or abundant, and the other species were either absent or rare. Four of the five species were dominant in at least 1 year. A review of literature on anostracans and analyses of annual weather patterns at Calgary were carried out in order to determine the cause of these erratic occurrence patterns and changes in species composition. For Eubranchipus bundyi, Branchinecta lindahli, and possibly Eubranchipus intricatus, the cause was probably due to long-term viability of eggs in association with species specific requirements of the embryo for certain quantities of precipitation at critical times of the year. It is suggested that when these precipitation requirements were ideal, hatching was substantial. For two other species, Branchinecta paludosa and Eubranchipus ornatus, erratic occurrence patterns could be explained by either the above or by a colonization–extinction hypothesis.
Foraging and habitat relationships of the sibling species Willow Flycatcher (Empidonax traillii) and Alder Flycatcher (E. alnorum) in southern Ontario
Authors: Barlow Jon C. , McGillivray W. Bruce
Published: May 2008

A northward expansion of the range of Willow Flycatchers has resulted in regions of secondary contact with Alder Flycatchers. The foraging ecology of both species overlaps extensively for both mutually allopatric and sympatric populations. Willow Flycatchers choose a more xeric upland habitat in southwestern Ontario than they do farther north at a site of secondary contact near Stouffville, Ontario. Alder Flycatchers at both Stouffville and Ottawa show similar habitat preferences. Habitat types chosen by both species at Stouffville overlapped considerably. Despite the extensive niche overlap at Stouffville, no evidence of competition between the species was observed.
Chinook salmon (Oncorhynchus tshawytscha) spawner characteristics in relation to redd physical features
Authors: Neilson John D. , Banford Christine E.
Published: May 2008

We studied the spatial pattern and physical characteristics of chinook salmon (Oncorhynchus tshawytscha) redds with respect to length of redd occupancy and when redd construction began. Spawners arriving first deposited their eggs in larger redds constructed in deeper, slower moving water. Redds constructed by late arriving fish were smaller on average and were usually located in relatively shallow, fast-flowing water. Late arriving fish also had a shorter average redd residence time. We suggest that progeny of early arriving spawners may have a selective advantage over progeny of late arriving fish in the same run.
Hummingbird–sapsucker associations in northern climates
Authors: Miller Richard S. , Nero Robert W.
Published: May 2008

The ruby-throated hummingbird has the most extensive breeding distribution of any hummingbird species in North America. In its most northern distribution in Canada, its spring arrival often occurs before herbaceous flowers are in bloom, and in many parts of its range it breeds in habitats where floral nectar is scarce or unavailable. Evidence is presented to support the hypothesis that the dates of spring arrival and northern breeding distribution of the ruby throat, and probably the rufous hummingbird, are determined by a commensal relationship with the yellow-bellied sapsucker, in which the principal energy source for the hummingbirds is sucrose in sap from trees drilled by the sapsuckers.
Reproductive tactics of pikas: why have two litters?
Authors: Smith Andrew T. , Ivins Barbara L.
Published: May 2008

Reproduction in a population of marked pikas (Ochotonaprinceps) was observed over a 3-year period in the Rocky Mountains of Colorado. Pikas were seasonally polyestrous; all adult females initiated two litters each summer. However, most females (24 of 25) weaned only a single litter. The number of successfully weaned litters and offspring was divided evenly between first and second breeding attempts. Previous studies had noted that less than 10% of juveniles emerged from second litters. Apparently females are capable of weaning second litters, but only if first litters are lost. Loss of first litters may result from nest predation or poor maternal condition caused by extreme winters. Reproductive constraints acting on pikas and their evolved reproductive tactics are compared with those of other alpine or boreal long-lived herbivorous small mammals.
Ultrastructural features of ovarian interstitial tissue in a wild mouse, Apodemus flavicollis, at various reproductive stages, with a note on its histochemistry at the onset of the breeding period
Authors: Eriksson Margareta , Nyholm Erik
Published: May 2008

In Apodemus flavicollis caught at the onset of the breeding season, interstitial tissue of the ovaries showed weak to moderate 3β-hydroxysteroid dehydrogenase and glucose-6-phosphate dehydrogenase activity. Interstitial cells were found to be actively secretory among females with open vaginas. The active cells were characterized by round nuclei and well-developed cytoplasmic organelles. The mitochondria were sometimes associated with smooth endoplasmic reticulum and had mainly tubular cristae. Lipid droplets were few and contained electron-dense material. A Golgi complex with associated vesicles was conspicuous, as were endo- or exo-cytotic vesicles. It is concluded that in A. flavicollis interstitial tissue is actively secretory in connection with ovulation or early pregnancy.
The labrum and labral sensilla of mosquitoes (Diptera: Culicidae): a scanning electron microscope study
Authors: Lee Robert M. K. W. , Craig D. A.
Published: May 2008

Labra of both sexes of 40 species of mosquitoes of 15 genera were examined using scanning electron microscopy, and 8 of these species using light microscopy, to investigate whether structural differences exist between labra of blood-sucking and non-blood-sucking mosquitoes. Three groups of sensilla are present in the apical region of labra of blood-sucking females: the apical sensilla, two uniporous sensilla; the subapical sensilla, two more uniporous sensilla; and further subapically, two campaniform sensilla. Only campaniform sensilla are found on labra of male mosquitoes. Labral sensilla are absent in the two Toxorhynchites species examined. Females of these two species are not known to feed on blood. The presence of apical sensilla and subapical sensilla appear to be related to blood-sucking habits of mosquitoes. These sensilla probably function in blood detection during feeding. Campaniform sensilla probably function as flow receptors. Cuticular microsculpture in various forms present on the dorsal wall of the labrum in the female suggests the presence of resilin in the wall of the labrum.
Feeding periodicity and the production of daily growth increments in otoliths of steelhead trout (Salmo gairdneri) and starry flounder (Platichthys stellatus)
Authors: Campana Steven E.
Published: May 2008

Juvenile steelhead trout (Salmo gairdneri) and starry flounders (Platichthys stellatus) were reared 64–76 days under various experimental feeding regimes to determine if feeding periodicity influenced the production of daily growth increments on the otoliths. Both species produced daily increments when fed thrice daily, daily, or once every 3 days, as well as through 26–32 days of starvation. Daily growth increments were also deposited in vateritic ("crystalline") otoliths, which constituted 27% of the trout sagittae sampled. Feeding frequency affected increment appearance and the incidence of subdaily increments in trout, but not in flounders. The difference in effect was probably due to the higher metabolic rate of trout. Increment deposition in all flounders was far more variable than in trout, and some flounders apparently ceased increment formation altogether.
Pleuroxus denticulatus and P. procurvus (Cladocera, Chydoridae) in North America: distribution, experimental hybridization, and the possibility of natural hybridization
Authors: Shan Robert K. , Frey David G.
Published: May 2008

In North America the two closely related Pleuroxus procurvus and P. denticulatus are presently sympatric over much of the region of continental glaciation and commonly occur in the same water bodies. Pleuroxus denticulatus extends southward quite generally through the United States into Middle America, whereas P. procurvus extends southward into New Mexico only at high elevations in the western mountains. Some early attempts at crossing northern with southern populations of P. denticulatus yielded a few hybrid offspring that were abnormal on hatching or otherwise died before reaching maturity, suggesting that two different taxa are involved. Attempts at crossing site sympatric populations of the two species in the laboratory yielded a single hybrid individual, which developed a clone with intermediate morphology. Hybrid males and ephippial females were incapable of mating successfully with themselves or with either parent. Thus, it is quite likely these species are incapable of hybridizing in nature. The two reports from North America of the European P. truncatus, which grossly resembles P. procurvus, are regarded as misidentifications. Pleuroxus uncinatus from Europe superficially resembles the experimental hybrid, but the several reports of P. uncinatus from the Pacific Northwest are regarded instead as possibly an undescribed species.
Origin of the insect wing and wing articulation from the arthropodan leg
Authors: Kukalová-Peck Jarmila
Published: May 2008

The most primitive known pterygote terga, wing articulation, wings, and upper leg segments with exites, occur in gigantic Upper Carboniferous Paleodictyoptera, Homoiopteridae. Fossil features are used as clues for reinterpreting some structures connected with flight in modern Pterygota. Brief comparisons with Paleozoic Diaphanopterodea, Permothemistida, Ephemeroptera, Protodonata, and with living Ephemeroptera, Odonata, and Neoptera are given. The wing articulation of all Pterygota is derived from a common ancestral ground plan based upon features present in fossils. The ancestral wings were articulated by a closely packed band of multiple sclerites which were hinged to eight lateral tergal lobes, and aligned with eight pairs of wing veins. The axillaria of Neoptera and axillary plates of Paleoptera are composite sclerites, which originated by fusion of several sclerites of the original band. Articular patterns of Paleoptera and Neoptera evolved differently and show (i) the presence or absence of a gap at the cubital level, (ii) the presence or absence of a turning–pivoting composite third axillary sclerite (3Ax), and (iii) a different composition of all composite sclerites. Gliding and wing folding adaptations within the articular band are discussed. A new fossil-based interpretation of veinal stems, veinal sectors, and of their fluting near the wing base is offered. An underlying symmetry of thoracic tergal sulci, articular sclerites, and wing venation seems to point to a nearly symmetrical, nonflying pro-wing engaged in up-and-down movement. Evidence of articulation in Paleozoic nymphal wings and evolution of metamorphic instars are examined. Pitfalls of paleoentomological work are discussed. Criteria for major divisions of Pterygota are reassessed. It is hypothesized that the wing originated from the first segment (epicoxa) of the euarthropodan upper leg and its exite. An epicoxal podomere became incorporated into the body wall and broke up into an articular ring of dorsal and ventral sclerites, and an epicoxal exite flattened and became a pro-wing. The pro-wing originally operated on a row of pivots from the epicoxa and subcoxa (pleuron) and became mobilized by epicoxal leg musculature.
Effects of Tai Chi on Gait Kinematics, Physical Function, and Pain in Elderly with Knee Osteoarthritis — A Pilot Study
Authors: Shen Chwan-Li , James C. Roger , Chyu Ming-C. , Bixby Walter R. , Brismée Jean-Michel , Zumwalt Mimi A. , Poklikuha Glen
Published: May 2008

Our previous study has demonstrated that 6 weeks of Tai Chi exercise significantly improves knee pain and stiffness in elderly with knee osteoarthritis. This study also examine the effects of Tai Chi exercise on gait kinematics, physical function, pain, and pain self-efficacy in elderly with knee osteoarthritis. In this prospective, pretest-posttest clinical trial, 40 men and women (64.4 ± 8.3 years) diagnosed with knee osteoarthritis participated in 6 weeks of instructed Tai Chi training, 1 hour/session, 2 sessions/week. The following measures were taken at baseline and the conclusion of the intervention: (a) gait kinematics including stride length, stride frequency, and gait speed quantified using video analysis, (b) physical function, (c) knee pain, and (d) pain self-efficacy. Data were analyzed using repeated MANCOVA, MANOVA, ANOVA and Wilcoxon tests. After 6 weeks of Tai Chi exercise, stride length ( p = 0.023; 1.17 ± 0.17 vs. 1.20 ± 0.14 m ), stride frequency ( p = 0.014; 0.91 ± 0.08 vs. 0.93 ± 0.08 strides/s), and consequently gait speed (p < 0.025; 1.06 ± 0.19 vs. 1.12 ± 0.15 m/s ) increased in the participants. Physical function was significantly improved ( p < 0.001) and knee pain was significantly decreased ( p = 0.002), while no change was observed in pain self-efficacy. In conclusion, these findings support that Tai Chi is beneficial for gait kinematics in elderly with knee osteoarthritis, and a longer term application is needed to substantiate the effect of Tai Chi as an alternative exercise in management of knee osteoarthritis.
Submerged Culture Mycelium and Broth of Grifola frondosa Improve Glycemic Responses in Diabetic Rats
Authors: Lo Hui-Chen , Hsu Tai-Hao , Chen Ching-Yi
Published: May 2008

Grifola frondosa, an edible fungus with a large fruiting body and overlapping caps, has been demonstrated to be a natural source of health-promoting substances, mainly due to its polysaccharides β-glucan. By using male Wistar rats injected with saline (normal rats) or nicotinamide plus streptozotocin (diabetic rats), we investigated the effects of an orally ingested placebo (CON and STZ groups), culture mycelium (CGM and SGM groups), broth (CGB and SGB groups), and mycelium plus broth (CGX and SGX groups) of Grifola frondosa on glycemic responses. During the experimental period (from day 0 to day 15), the STZ group had significantly lower body weight compared to the CON group (one-way ANOVA, p < 0.05). Moreover, the STZ group had significantly higher blood glucose concentrations at 2 hour-postprandial periods on days 0, 7, and 14 and in an oral glucose tolerance test (OGTT) on day 10, as well as significantly higher serum fructosamine and triglyceride on day 15 compared to the CON group. These diabetes-induced increases were significantly attenuated by administrations of mycelium and/or broth, i.e., the SGM, SGB, and SGX groups. The results of repeated-measures analysis and three-way ANOVA indicated that diabetes mellitus significantly increases, and mycelium administration significantly decreases postprandial blood glucose; diabetes mellitus significantly increases, and mycelium and broth administrations significantly decrease serum triglyceride, fructosamine, and blood glucose concentrations; moreover, in the area under the curve in OGTT, p < 0.05. Our results revealed that submerged-culture mycelia and broth of Grifola frondosa have bioactivities for improving glycemic responses.
Neuroprotection and Enhancement of Spatial Memory by Herbal Mixture HT008-1 in Rat Global Brain Ischemia Model
Authors: Kim Yun Tai , Yi Youn-Ju , Kim Mi-Yeon , Bu Youngmin , Jin Zhen Hua , Choi Hoyoung , Doré Sylvain , Kim Hocheol
Published: May 2008

To investigate whether HT008-1, a prescription used in traditional Korean medicine to treat mental and physical weakness, has a neuroprotective effect on a rat model of global brain ischemia and an enhancing effect against memory deficit following ischemia. Global brain ischemia was induced for 10 min by using 4-vessel occlusion (4-VO). HT008-1 was orally administered at doses of 30, 100, and 300 mg/kg respectively twice at 0 and 90 min after ischemia. The effect on memory deficit was investigated by using a Y-maze neurobehavioral test 4 days after brain ischemia, and the effect on neuronal damage was measured 7 days after ischemia. The mechanism of action was studied immunohistochemically using an anti-CD11b (OX-42) antibody. The oral administration of HT008-1 at 100 and 300 mg/kg significantly reduced hippocampal neuronal cell death by 49% and 53%, respectively, compared with a vehicle-treated group, and also improved spatial memory function in the Y-maze test. Immunohistochemically, HT008-1 inhibited OX-42 expression in the hippocampus. The effects of HT008-1 were more pronounced than those of its individual herb components. The herbal mixture HT008-1 protects the most vulnerable CA1 pyramidal cells of the hippocampus and enhances spatial memory function against global brain ischemia; an anti-inflammatory effect may be one of the mechanisms of action.
Therapeutic Effects of Baicalin on Lipopolysaccharide-Induced Acute Lung Injury in Rats
Authors: Huang Kun-Lun , Chen Chien-Sheng , Hsu Ching-Wang , Li Min-Hui , Chang Hung , Tsai Shih-Hung , Chu Shi-Jye
Published: May 2008

Baicalin is a flavonoid present in many traditional Chinese medicines. A number of studies show that baicalin has anti-inflammatory actions and protects against a variety of tissue and organ injuries. The effect of baicalin in lipopolysaccharide (LPS)-induced acute lung injury is not well studied. In this study, typically acute lung injury was induced in rat by intratracheal injection of LPS, which increased lactate dehydrogenase activity and protein content in bronchoalveolar lavage fluid, wet/dry lung weight ratio, Evan's blue dye leakage, and neutrophil infiltration. Baicalin (20 mg/kg) was administrated 1 hour before or 30 min after LPS injection. Both pre and post-treatment with baicalin attenuated the increase of these parameters and improved histological finding. Our results suggest that baicalin has a therapeutic effect on LPS-induced acute lung injury.
Mechanisms of Vitexin Preconditioning Effects on Cultured Neonatal Rat Cardiomyocytes with Anoxia and Reoxygenation
Authors: Dong Liu-Yi , Chen Zhi-Wu , Guo Yan , Cheng Xin-Ping , Shao Xu
Published: May 2008

This study was aimed at investigating the protective effect and mechanism of vitexin preconditioning (VPC) on cultured neonatal rat cardiomyocytes after anoxia and reoxygenation (A/R). An A/R model was established by using cultured neonatal rat cardiomyocytes. Cellular injury was evaluated by measuring cell viability, the releases of creatine kinase (CK), and lactate dehydrogenase (LDH). The apoptosis rate of cardiomyocytes after Anoxia/reoxygenation and the activities of extracellular signal-regulated protein kinases (ERKs) were measured. The intracellular calcium indicated by the fluorescence in cardiomyocytes was measured by the laser confocal microscope. Vitexin preconditioning (10, 30 and 100 μM) significantly enhanced the cell viability, markedly inhibited A/R-induced increases of LDH and CK release, obviously decreased the number of apoptotic cardiomyocytes and markedly decreased the fluorescence intensity value of [ Ca2+]iin cardiomyocytes. Exposure to anoxia or vitexin preconditioning significantly increased the phospho-ERK level, and the increase was markedly inhibited by PD98059, an inhibitor of the upstream kinase of ERK. These results suggest that vitexin preconditioning has a protective effect on cardiomyocytes A/R injury through the improvement of cell viability, decrease of LDH and CK release, such that the protective mechanism may relate to its ability to inhibit the cardiomyocytes apoptosis, reduce the cardiomyocytes calcium overload and increase the abundance of phosphor-ERK1/2 of the cardiomyocytes after anoxia and reoxygenation.
SME GROWTH STRATEGIES: ORGANIC OR NON-ORGANIC?
Authors: PASANEN MIKA
Published: May 2008

This paper focuses on factors affecting the growth and performance of small and medium enterprises (SMEs). The aim was to identify strategic factors differentiating two types of growth firms, organic growth SMEs and acquisition growth SMEs. The comparison was based on the empirical data of 20 acquisition growth SMEs and 90 organic growth SMEs, The analysis revealed strategic differences, with important implications, between the two groups. The most noteworthy differences were related to their scale of operation, firm age, founders, and product and customer structures. The results increase our understanding of the factors affecting SME growth and performance in two different contexts of growth strategies. They suggest that firm growth pattern is associated with SME characteristics, and thus has managerial implications.
INNOVATION MANAGEMENT AND ECONOMIC PERSPECTIVES: THE CASE OF GREECE
Authors: HATZIKIAN YANNIS , BOURIS JOHN
Published: May 2008

The level of the Greek economic growth is highly depended on three vital factors: a) entrepreneurship and business development b) innovation and creativity c) education and skills.

The correlation among these factors are direct and clear. This is why it is so important to monitor economic growth in respects of innovation, education and business development and to pursue a methodical policy to stimulate and reinforce them.

In this paper we focus on analysing the factors which affect the process of innovation in Greece in comparison with member states of European Union. More specific we attempt to measure innovation in Greek enterprises for the last decade and identify barriers to innovation in Greece as compared to other EU countries. We also evaluate the statistical relationship between per capita GDP (as a proxy to level of Greek people prosperity) and Research & Technological Development (RTD) Expenditure (as indicator to innovation-creativity activity) using Linear and Exponential Regression Models.

In the knowledge-driven economy, economic growth was achieved mainly through innovation, technology diffusion and new product applications. Therefore, we probe deep into considerations which influence -either positively or negatively - the advancement of the innovation activity, through empirical evidence and statistical methodology. Since, innovation and Research & Technological Development (RTD) are often considered as a main drive for economic development, recommendations proposed in this article become more intense and must be incorporated in the industrial infrastructure and in management attitudes at national and regional level.
Superior Temporal Sulcus—It's My Area: Or Is It?
Authors: Hein Grit , Knight Robert T.
Published: May 2008

The superior temporal sulcus (STS) is the chameleon of the human brain. Several research areas claim the STS as the host brain region for their particular behavior of interest. Some see it as one of the core structures for theory of mind. For others, it is the main region for audiovisual integration. It plays an important role in biological motion perception, but is also claimed to be essential for speech processing and processing of faces. We review the foci of activations in the STS from multiple functional magnetic resonance imaging studies, focusing on theory of mind, audiovisual integration, motion processing, speech processing, and face processing. The results indicate a differentiation of the STS region in an anterior portion, mainly involved in speech processing, and a posterior portion recruited by cognitive demands of all these different research areas. The latter finding argues against a strict functional subdivision of the STS. In line with anatomical evidence from tracer studies, we propose that the function of the STS varies depending on the nature of network coactivations with different regions in the frontal cortex and medial-temporal lobe. This view is more in keeping with the notion that the same brain region can support different cognitive operations depending on task-dependent network connections, emphasizing the role of network connectivity analysis in neuroimaging.
Visual Processing Affects the Neural Basis of Auditory Discrimination
Authors: Kislyuk Daniel S. , Möttönen Riikka , Sams Mikko
Published: May 2008

The interaction between auditory and visual speech streams is a seamless and surprisingly effective process. An intriguing example is the “McGurk effect”: The acoustic syllable /ba/ presented simultaneously with a mouth articulating /ga/ is typically heard as /da/ [McGurk, H., & MacDonald, J. Hearing lips and seeing voices. Nature, 264, 746–748, 1976]. Previous studies have demonstrated the interaction of auditory and visual streams at the auditory cortex level, but the importance of these interactions for the qualitative perception change remained unclear because the change could result from interactions at higher processing levels as well. In our electroencephalogram experiment, we combined the McGurk effect with mismatch negativity (MMN), a response that is elicited in the auditory cortex at a latency of 100–250 msec by any above-threshold change in a sequence of repetitive sounds. An “odd-ball” sequence of acoustic stimuli consisting of frequent /va/ syllables (standards) and infrequent /ba/ syllables (deviants) was presented to 11 participants. Deviant stimuli in the unisensory acoustic stimulus sequence elicited a typical MMN, reflecting discrimination of acoustic features in the auditory cortex. When the acoustic stimuli were dubbed onto a video of a mouth constantly articulating /va/, the deviant acoustic /ba/ was heard as /va/ due to the McGurk effect and was indistinguishable from the standards. Importantly, such deviants did not elicit MMN, indicating that the auditory cortex failed to discriminate between the acoustic stimuli. Our findings show that visual stream can qualitatively change the auditory percept at the auditory cortex level, profoundly influencing the auditory cortex mechanisms underlying early sound discrimination.
The Cortical Underpinnings of Context-based Memory Distortion
Authors: Aminoff Elissa , Schacter Daniel L. , Bar Moshe
Published: May 2008

Everyday contextual settings create associations that later afford generating predictions about what objects to expect in our environment. The cortical network that takes advantage of such contextual information is proposed to connect the representation of associated objects such that seeing one object (bed) will activate the visual representations of other objects sharing the same context (pillow). Given this proposal, we hypothesized that the cortical activity elicited by seeing a strong contextual object would predict the occurrence of false memories whereby one erroneously “remembers” having seen a new object that is related to a previously presented object. To test this hypothesis, we used functional magnetic resonance imaging during encoding of contextually related objects, and later tested recognition memory. New objects that were contextually related to previously presented objects were more often falsely judged as “old” compared with new objects that were contextually unrelated to old objects. This phenomenon was reflected by activity in the cortical network mediating contextual processing, which provides a better understanding of how the brain represents and processes context.