Ograniczanie wyników

Czasopisma help
Autorzy help
Lata help
Preferencje help
Widoczny [Schowaj] Abstrakt
Liczba wyników

Znaleziono wyników: 24

Liczba wyników na stronie
Pierwsza strona wyników Pięć stron wyników wstecz Poprzednia strona wyników Strona / 2 Następna strona wyników Pięć stron wyników wprzód Ostatnia strona wyników

Wyniki wyszukiwania

help Sortuj według:

help Ogranicz wyniki do:
Pierwsza strona wyników Pięć stron wyników wstecz Poprzednia strona wyników Strona / 2 Następna strona wyników Pięć stron wyników wprzód Ostatnia strona wyników
1
100%
Numerous plant species require passing through a cold period (stratification) for full germination of seeds. Seeds germinating prior to stratification frequently display positive photoblastism (i.e. do not germinate in darkness) and induced dormancy in far red light, that is under a leaf canopy absorbing selectively the near red light. Experiments with the seeds of 43 wild species have shown that after stratification they germinate profusely, frequently in darkness as well as in while light, but they still do not germinate in the far red. The two adaptation mechanisms are, therefore, not mutually exclusive, but occur jointly.
The study was aimed at estimating species composition and abundance of entomopathogenic fungi in the Chojnowski Landscape park. The effect of site, season (spring, summer, autumn) and temperature on the frequency of isolation of entomopathogenic fungi was also analysed. The effect of the first two factors was estimated based on the analysis of soil samples taken from meadow 1, forest 1 and orchard in spring, summer and autumn 2010. Three species of entomopathogenic fungi (Beauveria bassiana, Metarhizium anisopliae and Isaria fumosorosea) were isolated in the study area. Site and temperature affected the frequency of isolation of particular species. On meadow 1 and in orchard M. anisopliae appeared to be the dominating species while forest 1 was dominated by B. bassiana. From among meadow and forest sites sampled in the autumn, forest 3 (nature reserve) was characterised by the highest density of entomopathogenic fungi. M. anisopliae and B. bassiana were most often isolated from meadow sites while B. bassiana and I. fumosorosea - from forest sites. B. bassiana and I. fumosorosea infected insects with significantly higher frequency at 20°C than at 25°C.
n this work the reaction of Nicotiana tabacum cv. Bright Yellow 2 cells on the presence of 500 μM zinc, 500 μM cadmium, 10 μM copper and 5 μM iron was studied. It was confirmed that all tested heavy metals induced in tobacco cell suspension culture early stress response manifested by increased production of hydrogen peroxide. The highest level of hydrogen peroxide was marked in samples containing cadmium ions. This metal was also the most toxic for tested plant material. Less toxic were ions of copper and zinc. Iron ions gave the weakest stress response (probably because of the plant cell peroxidase inhibition).
In pot and field experiments, the emergence and bud appearance of Fat hen (Chenopodium album L.) were observed. The quantitative relationships between the day length and temperature, and the duration of the period between emerence and bud appearance were determined. Fat hen accelerates budding with shorter days. Under similar thermal and photoperiodic conditions buds appear earlier in autumn than in spring; no reason has been found for this regularity. Multiple regression equations describing the relationships studied are presented.
Background: Active sport tourism involves travelling in order to participate in different forms of movement recreation; engagement in physical activity is the primary aim of active sport tourism. Each and every decision regarding holiday, weekend or one-day trips is made based on several motives of different strength; it is the interaction between the motives that generates the ultimate behaviour of an individual. The aim of the study was to determine the motives behind the decision of holiday windsurfing camp participants to become engaged in this particular form of active sport tourism. Material/Methods: Seventy-three participants of windsurfing camps in Jastarnia (Hel Peninsula at the Polish seaside) entered the study, which was carried out in the form of a diagnostic survey. The research tool was an anonymous questionnaire. Results: The survey revealed considerable diversity regarding the types of active sport tourism undertaken by windsurfing camp participants in the year preceding data collection. The motives for participation in active sport tourism were also very different both among women and men. Nevertheless, social factors turned out to be of the greatest importance while making a decision about becoming involved in active sport tourism. Conclusions: Our study demonstrated that gender dimorphism had only been seen regarding the physical activity motive. Female respondents mentioned this particular motive for participation in the windsurfing camp more often than men.
Perception of light by phytochrome is one of the mechanisms that enable seeds to optimize the place and time of germination. In an effort to determine how widespread in nature is the inhibition of seed germination by light transmitted by competing plants, the seeds of various species were exposed for germination beneath leaf canopies. A high ratio of far red (FR) to red (R) light under the canopies inhibited to various extent the germination in most of samples. Only 91 species (out of 487 tested) did not indicate any FR-inhibition and might be determined as truly light-insensitive. Although particular seed samples of the same species often differ in response to white light (photoblastism), the responses to the FR irradiation seem to be much more stable. The ability to the FR-dormancy may be treated as a species-specific feature. After several-day exposure under leaf canopy, the seeds become extremely sensitive to the white light, but this sensitivity diminishes slowly in the course of treatment. Every seed cohort may be diversifi ed in germination by the irregular and variable structure of leaf canopy. The acquired state of photosensitivity may persist during several years and may impact on seed longevity. The seeds needing winter prechilling (stratifi cation) for a substantial germination, often become more indifferent to the white light, but always show a FR-sensitivity. The relations between taxonomic position and FR-sensitivity are weak. No difference in the FR-sensitivity was observed among life-forms. Distinct relations were stated between seed size and FR-sensitivity; seeds of FR-insensitive species are in average much larger. A relationship was found between the dynamics of germination and the photoresponses. Positively photoblastic and FR-sensitive seeds usually need much more time to full germination. These relationships may explain the fact that often the seeds of cultivated plants are photoblastically indifferent and FR-insensitive; they have been selected for fast and uniform germination. Full daylight exerted usually an inhibitory effect on germination of seeds of almost all tested species. The concept of positive photoblastism ought be treated with caution, because it proves true only in weak light.
In pot and field experiments the entergence, budding, flowering and ripening of Arabidopsis thaliana were observed. The quantitative relationships between phenology and climatic factors were determined using mainly multiple regression methods. Duration of periods between sowing and emergence and between flowering and ripening may be treated as hyperbolic functions of mean temperature and therefore the usual degreeday method can be applied. In the period between emergence and flowering the relationships are more complex; some modifications of methods relating development to temperature were used. A short vernalization after emergence, thereafter higher temperatures at long days accelerate flowering.
Ścieki deszczowe charakteryzuje duża zmienność pod względem ilościowym i jakościowym. Zmienność stopnia zanieczyszczenia ścieków jest pochodną wielu czynników, z których istotniejsze dotyczą składu zanieczyszczeń powietrza atmosferycznego, sposobu zagospodarowania terenu, parametrów opadu. Istotną rolę odgrywają też inne czynniki takie pora roku, sezonowa wegetacja roślin, wypadki komunikacyjne. W artykule przedstawiono wstępne wyniki badań jakości ścieków deszczowych oraz rozkład stężeń zanieczyszczeń w czasie trwania spływu na przykładzie zlewni miejskiej w Kielcach.
In this work the effect of cadmium, copper, iron and zinc on antioxidant enzymes activity in Nicotiana tabacum Bright Yellow 2 cells derived from suspension culture was studied. It was noticed that all of tested elements stimulated the increase in superoxide dismutases activities and initial increment, followed by the decrease in catalase activity. Zinc ions in 500 μM concentration caused continuous raise and copper ions in 10 μM caused decrease in the activities of nonspecific peroxidases. The presence of cadmium ions in 500 μM concentration in reaction mixture caused the initial decrease followed by increase in phenol peroxidases activities. Iron ions in 5 μM concentration induced the enhance of nonspecific peroxidase activity after the third hour of exposition.
Seed vigour, viability, the contents of soluble carbohydrates, total protein, albumins, and globulins, as well as seed coat structure, were analysed in yellow lupin (Lupinus luteus L.) cv. Iryd seeds stored for 20 years at -14oC, 0oC or at room temperature (approx. +20oC). Seed storage at room temperature reduced viability (to 2%) and increased seed leachate electroconductivity. Determinations of total proteins showed that protein content was significantly reduced in seeds stored at +20oC compared to the other storage regimens. Raffinose family oligosaccharides were the main soluble carbohydrates in seeds stored at 0oC and -14oC, whereas sucrose dominated in seeds stored at room temperature. Scanning electron microscopy (SEM) of seed surface and seed coat sections revealed appearance of an amorphic layer on the surface of seeds stored at room temperature (not observed in other seeds) and distinct shrinking of macrosclereid layer in seeds stored at -14oC. Macrosclereids layer in all seeds was 100 um thick and accounted for 60% of seed coat thickness. The obtained results suggest that for long term storage of lupin seeds at 0oC is the most advisable temperature if both costs of storage and seed storability are considered.
Introduction. Nutrition is a factor influencing physical and mental fitness. In this study we examine the lifestyle of university students and its impact on nutritional errors. Objective. To evaluate the dietary behaviours of students taking into account gender and nutritional knowledge. Material and methods. Using a QEB questionnaire, we were able to evaluate dietary behaviours and nutritional knowledge of respondents. Our analysis was conducted on data obtained from 456 students. Results. We found that nutritional knowledge for women was 34.7% satisfactory and 34.7% good. In contrast, nutritional knowledge for men varied, amounting to 40.2% satisfactory and 25.1% good. The number of meals and their regular consumption did not depend on gender or the nutritional knowledge of students, however, significant differences were recorded for the types of snacks they eat. A greater number of women than men snacked on sweets and biscuits, nuts and seeds, while in the case of salty snacks an opposite trend was observed. A higher level of nutritional knowledge correlated with the number of students snacking on fruit and vegetables instead of salty snacks. Moreover, it was observed that healthpromoting behaviours such as not adding sugar to beverages and not adding salt to dishes were more common with women and individuals with a higher level of nutritional knowledge. Conclusions. Women more frequently snack on sweets, biscuits, nuts and seeds. More men snack on salty snacks, add sugar to beverages and add salt to dishes. Individuals with insufficient nutritional knowledge more frequently snack on salty snacks rather than fruit. Students with insufficient nutritional knowledge more often commit nutritional errors.
20
Content available remote

The effect of fiberoptic bronchoscopy on exhaled nitric oxide

39%
Nitric oxide has been extensively studied as a noninvasive marker of airway inflammation. Assuming that bronchoscopy can produce not only systemic but also local inflammatory response, we hypothesized that bronchofiberoscopy can be responsible for an increase in nitric oxide synthesis with resulting increase in fractional concentration of exhaled nitric oxide (FENO). Fifty five subjects (F/M-23/32; mean age 53.9 ±17.3 yr) undergoing diagnostic bronchoscopy participated in the study. The indications for bronchoscopy were as follows: interstitial lung diseases (n=13; 23.6%), lung cancer (n=11; 20.0%), hemoptysis (n=10; 18.2%), differential diagnosis of asthma/dyspnea (n=9; 16.4%), pulmonary infections (n=7; 12.7%), and others (n=5; 9.1%). During bronchoscopy bronchial washing (n=18), bronchoalveolar lavage (BAL) (n=26), and bronchial biopsies (n=24) were performed. FENO was analyzed on-line with chemiluminescence analyzer (NIOX, Aerocrine, Sweden) according to the ATS guidelines, before and at 1, 2, 3 and 24 h after bronchoscopy. The mean FENO before bronchoscopy was 21.0 ±3.31(SE) ppb, it decreased to 14.8 ±2.10 ppb 1 h after bronchoscopy, reached a nadir at 2 h (14.4 ±2.28 ppb; P<0.05), and was not different from baseline 24 h after bronchoscopy (22.8 ±2.90 ppb). There were no differences in the FENO profile in BAL patients compared with those in whom only the bronchial washing was performed. We conclude that bronchoscopy leads to a decrease in FENO. The underlying mechanisms are at present unclear.
Pierwsza strona wyników Pięć stron wyników wstecz Poprzednia strona wyników Strona / 2 Następna strona wyników Pięć stron wyników wprzód Ostatnia strona wyników
JavaScript jest wyłączony w Twojej przeglądarce internetowej. Włącz go, a następnie odśwież stronę, aby móc w pełni z niej korzystać.