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TheSeventhInternationalWorkshoponSeedBiolo gywasheldfrom 1 2to 1 6May ,2 0 0 2inUniversityofSalamanca ,Spain .ThiswasthefirstworkshoptobeheldentirelyundertheInternationalSocietyforSeedScience(ISSS)banner.About 30 0seedscientistsfrom 2 0coun triesattendedthisworkshop .Aftertheopeningceremony ,thepresident_elect,Prof.DerekBewley ,fromGuelphUniversityofCanada ,openedwithastimulatingoverviewofseedsinscienceandsociety ,whichwasentitled“SeedsofHope,SeedsofDespair” .Hereviewedthehis tory…  相似文献   

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Summary Female freshwater eels injected with estradiol-17 (E2) for 15–78 days appear paler and secrete more mucus than controls. The resulting strongly opalescent blood plasma indicates that vitellogenin synthesis occurs in the liver, which shows a significant hypertrophy, an increased vacuolization (lipid material) and glycogen depletion. Plasma sodium is lowered, but calcium levels are considerably increased. The gonosomatic index increases (0.92±0.1 to a maximum of 2.21). Oocytes are enlarged, but the incorporation of vitellogenin remains discrete. Gonadotrophs (GTH cells), small and scarcely visible in the pituitary of control eels, are hypertrophied and contain numerous glycoprotein granules after E2-administration. E2 may act on the pituitary and/or hypothalamus via a positive feedback to induce gonadotrophin (GTH) synthesis; GTH release seems to be very limited as indicated by the ovarian response. The differentiation of GTH cells in eels treated with fish pituitary extracts is most probably due to secretion of E2 by the ovary, which reacts on the pituitary. Various hypotheses are considered to explain the low GTH release.Thyrotrophs, somatotrophs and prolactin cells of the pituitary are stimulated. In the pars intermedia, MSH and PAS-positive cells appear less active. A possible antidopaminergic effect of E2 is discussed.E2 administration constitutes a simple and economic technique to induce the synthesis of GTH and will facilitate the biochemical and biological study of the latter hormone in eels.  相似文献   

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Progenitor cell based therapies have emerged for the treatment of ischemic cardiovascular diseases where there is insufficient endogenous repair. However, clinical success has been limited, which challenges the original premise that transplanted progenitor cells would orchestrate repair. In this review, we discuss the basics of endothelial progenitor cell therapy and describe how microenvironmental changes (i.e., trophic and mechano-structural factors) in the damaged myocardium influence progenitor cell plasticity and hamper beneficial therapeutic outcome. Further understanding of these microenvironmental clues will enable optimization of cell therapy at all levels. We discuss current concepts and provide future perspectives for the enhancement of progenitor cell therapy, and merge these advances into a combined approach for ischemic tissue repair.  相似文献   

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During a primatological survey on the Río Curaray in north-eastern Peruvian Amazonia, observations on the ecology and behaviour of the golden-mantled tamarin, Saguinus tripartitus, were made. Two groups consisting of 6 and 9 individuals were observed. The diet of one group that was observed in some detail consisted of fruit, insects (tettigoniid orthopterans) and gums. Patterns of height use were very similar to those observed in saddle-back tamarins, Saguinus fuscicollis. This similarity and the lack of evidence for sympatry with either S. fuscicollis or S. nigricollis lead to the suggestion that S. tripartitus should be reconsidered as a subspecies of S. fuscicollis rather than a species on its own; alternatively, other subspecies of S. fuscicollis should be raised in taxonomic rank.  相似文献   

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Alignment is a spontaneous behavioral preference of particular body orientation that may be seen in various vertebrate or invertebrate taxa. Animals often optimize their positions according to diverse directional environmental factors such as wind, stream, slope, sun radiation, etc. Magnetic alignment represents the simplest directional response to the geomagnetic field and a growing body of evidence of animals aligning their body positions according to geomagnetic lines whether at rest or during feedings is accumulating. Recently, with the aid of Google Earth application, evidence of prevailing North–South (N–S) body orientation of cattle on pastures was published (Begall et al. PNAS 105:13451–13455, 2008; Burda et al. PNAS 106:5708–5713, 2009). Nonetheless, a subsequent study from a different laboratory did not confirm this phenomenon (Hert et al. J Comp Physiol A 197:677–682, 2011). The aim of our study was to enlarge the pool of independently gained data on this remarkable animal behavior. By satellite snapshots analysis and using blinded protocol we scored positions of 2,235 individuals in 74 herds. Our results are in line with the original findings of prevailing N–S orientation of grazing cattle. In addition, we found that mutual distances between individual animals within herds (herd density) affect their N–S preference—a new phenomenon giving some insight into biological significance of alignment.  相似文献   

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Background

Although being a simple and effective index that has been widely used to evaluate academic output of scientists, the h-index suffers from drawbacks. One critical disadvantage is that only h-squared citations can be inferred from the h-index, which completely ignores excess and h-tail citations, leading to unfair and inaccurate evaluations in many cases.

Methodology /Principal Findings

To solve this problem, I propose the h’-index, in which h-squared, excess and h-tail citations are all considered. Based on the citation data of the 100 most prolific economists, comparing to h-index, the h’-index shows better correlation with indices of total-citation number and citations per publication, which, although relatively reliable and widely used, do not carry the information of the citation distribution. In contrast, the h’-index possesses the ability to discriminate the shapes of citation distributions, thus leading to more accurate evaluation.

Conclusions /Significance

The h’-index improves the h-index, as well as indices of total-citation number and citations per publication, by possessing the ability to discriminate shapes of citation distribution, thus making the h’-index a better single-number index for evaluating scientific output in a way that is fairer and more reasonable.  相似文献   

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I review the distribution of genus Alouattain the Marajó Archipelago based on geographic variation of pelage color patterns. Specific differences exist among the labeled specimens at Museu Paraense Emílio Goeldi, which are confirmed via new field information from wild populations. The animals from Marajó, Caviana, and Mexiana Islands possess color patterns of Alouatta belzebul,while Alouatta seniculusis confirmed as the species that inhabits Gurupá Island. The high variability of pelage coloration of the animals from Marajó, Caviana, and Mexiana Islands includes all phenotypes formerly designated as different subspecies. The howler populations from these three islands belong to the same subspecies as those populations that inhabit the region of Tucurui dam reservoir (area 4). Finally, it seems that, as also suggested by chromosome studies, A. belzebulprobably comprises different epiphenotypes without taxonomic validity.  相似文献   

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I review the distribution of genus Alouattain the Marajó Archipelago based on geographic variation of pelage color patterns. Specific differences exist among the labeled specimens at Museu Paraense Emílio Goeldi, which are confirmed via new field information from wild populations. The animals from Marajó, Caviana, and Mexiana Islands possess color patterns of Alouatta belzebul,while Alouatta seniculusis confirmed as the species that inhabits Gurupá Island. The high variability of pelage coloration of the animals from Marajó, Caviana, and Mexiana Islands includes all phenotypes formerly designated as different subspecies. The howler populations from these three islands belong to the same subspecies as those populations that inhabit the region of Tucurui dam reservoir (area 4). Finally, it seems that, as also suggested by chromosome studies, A. belzebulprobably comprises different epiphenotypes without taxonomic validity.  相似文献   

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Zusammenfassung Biloxi-Soja-Bohnen (Glycine max. L. Merr) erhielten photoperiodische Cyclen, die aus 8-oder 9stündigen Lichtperioden und unterschiedlich langen Dunkelperioden bestanden. Die Dunkelperioden wurden zu verschiedenen Zeitpunkten durch halbstündiges Störlicht unterbrochen. Die Wirkung dieser unterschiedlichen Behandlungen wurde durch Messung der Blühreaktionen bestimmt.Ein Störlicht, welches in frühen Abschnitten der langen Dunkelperiode geboten wird, verhindert die Blütenbildung unabhängig von der Länge des Gesamtcyclus, dem die Pflanzen ausgesetzt werden. Diese Unterdrückung erreicht ihr Maximum mit einem Störlicht, welches 8 Std nach dem Beginn der Dunkelperiode wirkt; die Hemmung ist schwächer, wenn das Störlicht früher geboten wird. Ein Störlicht, das gegen Ende der Dunkelperiode geboten wird, reduziert die Blütenbildung ebenfalls. Dieser Effekt erreicht sein Maximum mit einem Störlicht, welches ungefähr 8 Std vor dem Ende der Dunkelperiode geboten wird, er wird mit abnehmender Länge der nach dem Störlicht folgenden Dunkelperiode kleiner. Die Wirkung von Störlicht, das zu anderen Zeiten während der Dunkelperiode geboten wird, hängt von der Länge des Gesamtcyclus ab. Bei Cycluslängen, die für Blütenbildung ungünstig sind, kann solches Störlicht blühfördernd wirken.

Wit 7 Figures in the Text

Supported in part by a National Science Foundation grant toKarl C. Hamner.  相似文献   

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A study of the environmental radioactivity in the Kopa?ki Rit Nature Park, Croatia, is presented. This wildlife reserve is part of the Middle Danube River Basin, and it is exposed to various pollutants due to a number of human activities in the surroundings, where there is a nuclear power plant and also urban centres and areas of intense agricultural production. Results for the activity concentrations of soil and surface water samples do not indicate any elevated radioactivity level, which is confirmed by on-site measurements of ambient dose rate equivalent. An assessment of the radiological load on the local biota, carried out using the ERICA tool, implies an overall low radiological risk even if conservative values of the risk quotient are used. Therefore, human activities do not have a significant effect on the radiological load on the Kopa?ki Rit area. A similar conclusion might be made with regard to numerous similar environments in the Middle Danube River Basin.  相似文献   

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The fatal autosomal recessive disease cystic fibrosis (CF) is caused by mutations in the gene which encodes the cystic fibrosis transmembrane conductance regulator (CFTR). Many of these disease-causing mutations, including the deletion of F508 (F508) which accounts for approximately 70% of the disease alleles, occur in one of the two consensus nucleotide binding sequences. Peptide studies have directly demonstrated that the N-terminal nucleotide binding sequences bind adenine nucleotides. Structurally, circular dichroism spectropolarimetry indicates that this region of CFTR assumes a -stranded structure in solution. The F508 mutation causes a diminution in the amount of -stranded structure and a concomitant increase in the amount of random coil structure present, indicating that either the mutant peptide has a different native structure or that the conformational equilibrium is shifted toward a more disordered form. Furthermore, the mutant peptide is more sensitive to denaturation, indicating that F508 is a stability, or protein-folding mutant. Here we review these results and discuss their implications for interpreting the behavior of F508in situ and for the rational design of new CF drugs.  相似文献   

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In the Loess Plateau, China, arable cultivation of slope lands is common and associated with serious soil erosion. Planting trees or grass may control erosion, but planted species may consume more soil water and can threaten long‐term ecosystem sustainability. Natural vegetation succession is an alternative ecological solution to restore degraded land, but there is a time cost, given that the establishment of natural vegetation, adequate to prevent soil erosion, is a longer process than planting. The aims of this study were to identify the environmental factors controlling the type of vegetation established on abandoned cropland and to identify candidate species that might be sown soon after abandonment to accelerate vegetation succession and establishment of natural vegetation to prevent soil erosion. A field survey of thirty‐three 2 × 2–m plots was carried out in July 2003, recording age since abandonment, vegetation cover, and frequency of species together with major environmental and soil variables. Data were analyzed using correspondence analysis, classification tree analysis, and species response curves. Four vegetation types were identified and the data analysis confirmed the importance of time since abandonment, total P, and soil water in controlling the type of vegetation established. Among the dominant species in the three late‐successional vegetation types, the most appropriate candidates for accelerating and directing vegetation succession were King Ranch bluestem (Bothriochloa ischaemum) and Lespedeza davurica (Leguminosae). These species possess combinations of the following characteristics: tolerance of low water and nutrient availability, fibrous root system and strong lateral vegetative spread, and a persistent seed bank.  相似文献   

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Summary During the 1977 and 1979 reproductive periods of the Galápagos fur seals a census taken in the mornings and evenings at Cabo Hammond, Fernandina, showed a marked, synodic lunar rhythm in numbers of animals ashore. About twice as many fur seals were ashore at full moon than at new moon. By use of two independent Fourier analysis methods, the curve of the morning counts is shown to lag 15°–20° of the lunar month behind the curve of the evening counts. The lunar effect is demonstrated for males, females, and immatures. The rhythm is also seen is demonstrated for males, females, and immatures. The rhythm is also seen in attendance data from 13 individually marked females, all but one nursing young. Reproductive events show the lunar rhythm much less markedly than do numbers ashore. This and the clear rhythm in immature numbers make it very likely that the rhythm is a year-round phenomenon, independent of reproduction.There is no reason to assume that fur seals stay on land during moonlit nights especially for social interaction. It is then hypothesized that fur seals avoid moonlight at sea. If so, the peak of numbers ashore at full moon and the negative phase angle difference of the evening curve against the morning curve can be explained with the shift, and the varying duration and brightness, of the moonlit part of the night over the lunar cycle. Two hypotheses which might account for this moonlight avoidance are discussed: (1) predator (shark) avoidance and (2) varying feeding efficiency of the fur seals due to the influence of moonlight on the vertical distribution of prey.  相似文献   

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