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21.
Troy A. Baird 《Environmental Biology of Fishes》1993,38(4):393-397
Synopsis The bar jack,Caranx Tuber, was commonly observed to follow individual puddingwife wrasses,Halichoeres radiatus, that were foraging on the substrate. Individuals of both species actively pursued the other to maintain these heterospecific foraging teams, were sometimes attracted to feeding acts initiated by team partners, and the foraging rates of teamed jacks and wrasses were positively correlated. Pilfering of food items was rare, suggesting little, if any, competition cost of this foraging association. The ratio of bites to search in teamed jacks was over three times that when solitary, and jacks were sometimes aggressive to conspecifics attempting to join their team, suggesting that the association is beneficial to the jacks. Both bite and search rates were higher in puddingwifes when teamed with a jack, indicating that the association also benefits the wrasses. Benefits to puddingwifes may be derived directly from attendants because wrasses were sometimes attracted to jack foraging acts. However, increased foraging in wrasses may also be a consequence of heightened motivation to feed owing to heterospecific social facilitation. 相似文献
22.
Maarten Jaap Erik Broekman Selwyn Hoeks Rosa Freriks Merel M. Langendoen Katharina M. Runge Ecaterina Savenco Ruben ter Harmsel Mark A. J. Huijbregts Marlee A. Tucker 《Global Ecology and Biogeography》2023,32(2):198-205
Motivation
Home range is a common measure of use of space by animals because it provides ecological information that is useful for conservation applications. In macroecological studies, values are typically aggregated to species means to examine general patterns of use of space by animals. However, this ignores the environmental context in which the home range was estimated and does not account for intraspecific variation in home range size. In addition, the focus of macroecological studies on home ranges has historically been biased towards terrestrial mammals. The use of aggregated numbers and the terrestrial focus limit our ability to examine home-range patterns across different environments, their variation in time and variation between different levels of organization. Here, we introduce HomeRange, a global database with 75,611 home-range values across 960 different species of mammals, including terrestrial, aquatic and aerial species.Main types of variables contained
The dataset contains estimates of home ranges of mammals, species names, methodological information on data collection, method of home-range estimation, period of data collection, study coordinates and name of location, in addition to species traits derived from the studies, such as body mass, life stage, reproductive status and locomotor habit.Spatial location and grain
The collected data are distributed globally. Across studies, the spatial accuracy varies, with the coarsest resolution being 1°.Time period and grain
The data represent information published between 1939 and 2022. Across studies, the temporal accuracy varies; some studies report start and end dates specific to the day, whereas for other studies only the month or year is reported.Major taxa and level of measurement
Mammalian species from 24 of the 27 different taxonomic orders. Home-range estimates range from individual-level values to population-level averages.Software format
Data are supplied as a comma-delimited text file (.csv) and can be loaded directly into R using the “HomeRange” R package ( https://github.com/SHoeks/HomeRange ). 相似文献23.
24.
Influence of molecular configuration on the passage of macromolecules across the glomerular capillary wall 总被引:4,自引:0,他引:4 下载免费PDF全文
M P Bohrer W M Deen C R Robertson J L Troy B M Brenner 《The Journal of general physiology》1979,74(5):583-593
The influence of molecular configuration on the filtration of macromolecules across glomerular capillary walls was examined by comparing fractional clearances of two uncharged polysaccharides of distinctly different molecular configuration in the Munich-Wistar rat. The macromolecules employed were dextran, a slightly branched polymer of glucopyranose, and ficoll, a highly cross-linked copolymer of sucrose and epichlorohydrin. Differences in effective shape between these two polymers were determined from measurements of several physical properties of aqueous solutions containing either dextran or ficoll. It was found that dextran is best represented as a prolate ellipsoid with axial ratios of 4, 9, and 16 for molecules with Stokes-Einstein radii of 22, 32, and 40 A, respectively. On the other hand, ficoll is more closely approximated as spherical since the axial ratio was found to be between 1 and 2 for all molecular sizes. Fractional clearances of dextran and ficoll ranging in effective radius from 18 to 44 A were determined in each of seven Munich-Wistar rats. Fractional clearances of dextran were found to be greater than those of ficoll, the difference being significant for molecular radii ranging from 24 to 44 A. In addition, as shown previously for dextran, ficoll was found to be neither secreted nor reabsorbed by the renal tubules. These results, therefore, suggest that in addition to molecular size and charge, molecular configuration is also a determinant of the filtration of macromolecules across the glomerular capillary wall. 相似文献
25.
Summary We have recently shown that stimulation of electrogenic HCO
3
–
secretion is accompanied by a simultaneous increase in short-circuit current (I
sc, equivalent to HCO
3
–
secretion rate under these conditions), apical membrane capacitance (C
a
, proportional to membrane area), and apical membrane conductance (G
a
, proportional to membrane ionic permeability). The current experiments were undertaken to explore the ionic basis for the increase inG
a
and the possibility that the rate of electrogenic HCO
3
–
secretion is regulated by changes inG
a
. Membrane electrical parameters were measured using impedance-analysis techniques before and after stimulation of electrogenic HCO
3
–
secretion with cAMP in three solutions which contained different chloride concentrations. In another series of experiments, the effects of an anion channel blocker, anthracene-9-carboxylic acid (9-AA), were measured after stimulation of electrogenic HCO
3
–
secretion with cAMP. The major conclusions are: (i) a measurable apical Cl– conductance exists in control hemibladders; (ii) the transport-associated increase inG
a
includes a Cl–-conductive component; (iii)G
a
also appears to reflect a HCO
3
–
conductance; (iv) the relative magnitudes of the apical membrane conductances to Cl– and HCO
3
–
are similar; (v) 9-AA reducesG
a
andI
sc appear cAMP-stimulated hemibladders; and (vi) alterations inI
sc appear to be mediated by changes inG
a
. 相似文献
26.
Tetrazolium [3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide] reduction by mycoplasmas.
H Kirchhoff C Maass M Runge B Franz R Schmidt H Quentmeier P F Mühlradt 《International journal of systematic bacteriology》1992,42(3):506-508
We investigated 22 mycoplasma and acholeplasma species for their ability to reduce tetrazolium salts by using the MTT [3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide] assay. The test results were evaluated visually, as well as spectrophotometrically, by using an enzyme-linked immunosorbent assay reader. Our results were very similar to the results obtained when the tetrazolium salt reduction assay described by Aluotto et al. was used. However, the MTT reduction assay appeared to be better because it is faster, more objective and sensitive, easier to evaluate, and less expensive; in addition, it allows quantitative determinations. By using regression analysis a linear correlation between formazan production and the number of colony-forming units was demonstrated for all of the species investigated, indicating that the MTT assay can also be used for growth, toxicity, or chemosensitivity tests for the mycoplasma species that are capable of reducing tetrazolium salts. 相似文献
27.
Troy J. Beeler Raymond H. Farmen Anthony N. Martonosi 《The Journal of membrane biology》1981,62(1-2):113-137
Summary The mechanism of voltage-sensitive dye responses was analyzed on sarcoplasmic reticulum vesicles to assess the changes in membrane potential related to Ca2+ transport. The absorbance and fluorescence responses of 3,3-diethyl-2,2-thiadicarbocyanine, 3,3-dimethyl-2,2-indodicarbocyanine and oxonol VI during ATP-dependent Ca2+ transport are influenced by the effect of accumulated Ca2+ upon the surface potential of the vesicle membrane. These observations place definite limitations on the use of these probes as indicators of ion-diffusion potential in processes which involve large fluctuations in free Ca2+ concentrations. Nile Blue A appeared to produce the cleanest optical signal to negative transmembrane potential, with least direct interference from Ca2+, encouraging the use of Nile Blue A for measurement of the membrane potential of sarcoplasmic reticulumin vivo andin vitro. 1,3-dibutylbarbituric acid (5)-1-(p-sulfophenyl)-3 methyl, 5-pyrazolone pentamethinoxonol (WW 781) gave no optical response during ATP-induced Ca2+ transport and responded primarily to changes in surface potential on the same side of the membrane where the dye was applied. Binding of these probes to the membrane plays a major role in the optical response to potential, and changes in surface potential influence the optical response by regulating the amount of membrane-bound dye. The observations are consistent with the electrogenic nature of ATP-dependent Ca2+ transport and indicate the generation of about 10 mV inside-positive membrane potential during the initial phase of Ca2+ translocation. The potential generated during Ca2+ transport is rapidly dissipated by passive ion fluxes across the membrane. 相似文献
28.
Determination of serum protein concentration in nanoliter blood samples using fluorescamine or 9-phthalaldehyde. 总被引:15,自引:0,他引:15
Fluorometric procedures were developed to permit measurement of total protein concentration in nanoliter serum samples, using either fluorescamine or o-phthalaldehyde. The sensitivities of assays using these two reagents were similar, but the o-phthalaldehyde method was found to be somewhat simpler and more reproducible. Accurate measurements could be obtained on serum samples of 4 to 5 nl with either reagent, by using a serum standard. Fluorescence differed considerably among individual serum proteins, albumin generally showing greater fluorescence than globulins. Small molecular weight species in serum did not contribute appreciably to total serum fluorescence with either reagent. 相似文献
29.
Agarose slab-gel electrophoresis equipment. 总被引:28,自引:0,他引:28
Simple slab-gel molds which utilize the electrophoresis apparatus described by F. W. Studier (J. Mol. Biol.79, 237 (1973)) have been designed for pouring and running agarose slab-gels. Analytical gels in which many samples are run simultaneously facilitate the assay of many enzymes which lead to physical changes in DNA, whereas the preparative gels allow the separation of large quantities (1–20 mg) of DNA fragments. 相似文献
30.
Raquel Santos Jorge Troy R. Hawkins Edgar G. Hertwich 《The International Journal of Life Cycle Assessment》2012,17(1):9-15