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  • 1
    ISSN: 1432-1793
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract An earlier study showed large changes in ovarian phosphoprotein, a characteristic component of vertebrate yolk, during post-vitellogenic meiotic maturation (ripening) of ovaries of teleosts with pelagic eggs. Here, the study of four phosphorus-containing ovarian fractions is extended to other teleost families with pelagic eggs and to species with demersal eggs. Fishes were caught in the sea and lakes of western Scotland between 1982 and 1984. In the codGadus morhua, spratSprattus sprattus, dragonetCallionymus lyra, Norway poutTrisopterus esmarkii, saithePollachius virens, lingMolva molva and flounderPlatichthys flesus, all of which spawn pelagic eggs, the massive water influx during ripening which renders the eggs buoyant was accompanied by large changes in yolk phosphoprotein which were apparent as decrease or disappearance of protein phosphorus as conventionally determined. During ripening of the demersal eggs of the herringClupea harengus, both the water uptake and the decrease in protein phosphorus were less pronounced. In the three-spined sticklebackGasterosteus aculeatus, sea sticklebackSpinachia spinachia, sand gobyPomatoschistus minutus and perchPerca fluviatilis, little or no changes in water content or protein phosphorus both usually increased in species with pronounced water uptake and decreased in species with little or no water uptake. Lipid phosphorus showed little change in all species examined except herring, in which it increased. It is concluded that the characteristic changes in phosphoprotein and other phosphorus-containing fractions are most pronounced in species with pelagic eggs exhibiting massive water uptake on ripening, but are found to a lesser extent in species with demersal eggs in which considerable water uptake accompanies ripening.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Oecologia 83 (1990), S. 299-308 
    ISSN: 1432-1939
    Keywords: Patterns ; Patch use ; Grasshoppers ; Communities ; Habitat type
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary A study was conducted to evaluate differences in rangeland grasshopper communities over environmental gradients in Gallatin Valley, Montana, USA. The concept of habitat type (Daubenmire 1966) was used as a basis for discriminating between groupings of patches based on vegetation. A total of 39 patches were selected that represented five recognized grassland habitat types (Mueggler and Stewart 1980), as well as two disturbed types (replanting within a known habitat type). Repeated sampling in 1988 of both the insect and plant communities yielded a total of 40 grasshopper (19 664 individuals) and 97 plant species. Detrended Correspondence Analysis (DCA) indicated that patch classifications based on presence and percent cover of plants were appropriate and showed good between-group (habitat type) separation for patches along gradients of precipitation/elevation and plant community complexity. Results from undisturbed habitats showed that plant and grasshopper species composition changed over observed environmental gradients and suggested that habitat type influenced not only species presence, but also relative abundance. Discussion is presented that relates results with patch-use and core and satellite species paradigms.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Calcified tissue international 35 (1983), S. 339-343 
    ISSN: 1432-0827
    Keywords: Ca depletion ; Growth hormone ; Prolactin ; Vitamin D
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Summary Twelve hours after the diet of 3-week-old chicks was changed from a 1% to a 0.1% concentration of calcium (Ca), the growth rate and circulating levels of growth hormone had fallen while renal 25-hydroxecholecaiferol-24-hydroxylase had risen. The amount of47Ca incorporated into bone from an injection given 18 h previously was lower than in the control birds. Over the following 21/2 days on the low Ca diet, the renal 1-hydroxylase activity rose and the plasma prolactin level fell, but the other parameters moved back toward the control level. It was concluded that early adjustments in hormonal and mineral metabolism counteract the acute effects of a dietary Ca shortage until longer-term adaptive changes begin to compensate for a continuing Ca deficiency. The renal hydroxylase activities were not directly influenced by the level of circulating growth hormone or prolactin.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Cellular and molecular life sciences 43 (1987), S. 602-604 
    ISSN: 1420-9071
    Keywords: Somatostatin ; growth hormone ; serotonin
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The inhibitory effects of pargyline and quipazine on chicken growth hormone secretion were overcome by passive immunoneutralization of endogenous somatostatin (SRIF)-14 or SRIF-28(1–14)-like immunoreactivity. Administration of the specific antisera to control birds pretreated with 0.9% NaCl elevated the basal plasma GH concentrations. These results suggest that peptides with SRIF-14 or SRIF-28(1–14)-like immunoreactivity tonically inhibit GH secretion and are at least partially responsible for the inhibitory effects of pargyline and quipazine on GH release in immature domestic fowl.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Springer
    Cellular and molecular life sciences 46 (1990), S. 109-113 
    ISSN: 1420-9071
    Keywords: preputial gland ; aversive stimulus ; submission-dominance ; mice ; olfactory preference ; farnesene ; chemosignals
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Two terpenic constituents, E,E,-α-farnesene and E-β-farnesene, were found to be elevated in dominant male urine when compared to subordinate or control males. These two urinary compounds were absent in the bladder urine of males; however, they were the most prominent constituents of the preputial gland's aliquots. The results of a two-choice preference test, conducted on ICR/Alb subordinate males, gave a strong indication that these two terpenic constituents introduced into the previously attractive stimulus significantly discouraged prolonged investigations by male mice. The compounds, whether present in the urine matrix or water, rendered the stimulus with a quality behaviorally similar to the urine of dominant males. It appears that they may be synonymous with the previously described aversion signal produced by dominant males. We suggest that these compounds may play a wide-ranging role in the territorial marking behavior of male mice.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Springer
    Cellular and molecular life sciences 51 (1995), S. 738-743 
    ISSN: 1420-9071
    Keywords: Male mouse pheromones ; stereospecific response ; chromatographic resolution of optical isomers ; estrus synchronization
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract Two male mouse pheromones, 3,4-dehydro-exo-brevicomin (DHB) and 2-sec-butyldihydrothiazole (SBT), are chiral molecules which were previously tested in their respective bioasays as racemic mixtures. The focus of this study has been to determine the absolute configuration of their natural forms and its relation to stereospecific biological action. DHB was established as the R,R-enantiomer possessing biological activity. Due to an extremely easy racemization of SBT under very mild conditions, enantioselectivity of its transmission and its action at the receptor site appear to be of secondary importance.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    Springer
    Cellular and molecular life sciences 34 (1978), S. 1096-1097 
    ISSN: 1420-9071
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary In immature cockerels adrenaline administration lowered the levels of plasma growth hormone. Both alpha and beta adrenergic receptor agonists also depressed the circulating growth hormone levels. In the presence of beta blockade, the suppressive effect of adrenaline on growth hormone secretion was not observed.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    Springer
    Cellular and molecular life sciences 35 (1979), S. 694-695 
    ISSN: 1420-9071
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The effect of an acid extract of chicken hypothalami on the in vitro secretion of prolactin and growth hormone (GH) by dispersed chicken pituitary cells has been investigated. Both prolactin and GH release were stimulated in a dose related manner in the presence of the hypothalamic extract (HE). Somatostatin had no effect on the basal or HE stimulated release of prolactin although it did inhibit the HE induced release of GH.
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  • 9
    Electronic Resource
    Electronic Resource
    Springer
    Cellular and molecular life sciences 33 (1977), S. 1242-1243 
    ISSN: 1420-9071
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Chloral hydrate, Equithesin, Althesin, Rompun, Sagatal and ether anaesthesia lowered the concentration of plasma growth hormone in immature cockerels. Handling and serial bleeding of the conscious controls had no effect on the growth hormone concentration.
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  • 10
    ISSN: 1522-9602
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Mathematics
    Notes: Abstract Experimental data of the radial incorporation of labeled cholesterol [14C-4] into the artery wall is regressed against a mathematical model that predicts macromolecular transport in this biological system. Data is obtained using excised canine carotid arteries that are perfusedin vitro under pulsatile hemodynamic conditions for 2 hr. Vessels are exposed to either normotensive hemodynamics, hypertensive hemodynamics, or simulations in which the rate of flow or vessel compliance is deliberately altered. Several arteries are studied under normotensive conditions following balloon catheter deendothelialization. Transmural concentration profiles of [14C-4] activity are determined by microcryotomy of longitudinal sections of perfused vessels. Nonlinear Marquardt regression on 12 experimental cases yields parameter estimates of effective diffusivity,D and solute filtration velocity,V. Results of this experimental investigation support our hypothesis that hemodynamics and the endothelial lining influence wall flux in intact vessels. Exposure to altered (vs normotensive) hemodynamics is associated with increased incorporation of labeled cholesterol. A similar observation is made for deendothelialized vessels (e.g. a greater accumulation of label and a rise in convective flux). Based upon our companion measurements of vessel wall forces and endothelial cellular morphology accompanying hemodynamic simulations, we suggest that hemodynamically induced alterations to endothelial structures lead to the increased permeability, convection and incorporation that we observe in this work.
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