Strong Stress Factor Research Articles

Some Sociological, Legislative and Pedagogical Aspects of the Prevalence of Mobbing among Teachers in Primary School (Case Study)

Abstract The paper sets forth the discussion of the occurrence of mobbing in Slovene elementary school. The study is based on empirical facts collected at three different schools. There are some differences between organizations in occurrence, victims’ characteristics, the reasons and consequences of mobbing. The results of the empirical research of the psychosocial conditions in the analysed working places show that more and more teachers as employees are becoming mobbing victims. Mobbing is defined as a very strong social stress factor. Each individual or social group experiences mobbing at work as a conflict situation and communication. An attacked individual as a victim of the conflict is exposed to permanent and long-term attacks by one or more people at work. The intention of these attacks is to oust the individual from the organization or to harm him/her in other ways. A lot of pressure is being imposed on the person and also intimidation, humiliation, molestation or other negative influences appear. Because of the psychic burden the victim usually becomes ill and often leaves the working position. Mobbing can affect the individual in a way that s/he is no longer capable of fitting into any new working environment. The most frequent consequences named by the victims are: stress, insomnia, concentration problems and family problems.

Nitrate reductase from Triticum aestivum leaves: Regulation of activity and possible role in production of nitric oxide

Nitrate reductase (NR) and peroxidase (POX) are important enzymes involved in the metabolism of reactive oxygen (ROS) and nitrogen species in leaves of wheat (Triticum aestivum L.) seedlings. It has been confirmed that NR activity in wheat leaves depends on the light conditions and the presence of nitrates during the cultivation of the seedlings, and it is regulated by the molybdenum cofactor and phosphorylation. In the present study, confocal microscopy and EPR spectroscopy studies showed that the addition of nitrite, a product of NR, increased the level of nitric oxide (NO). This increase was prevented by the addition of sodium azide, an inhibitor of NR. The results suggest that in wheat leaves one of the key functions of NR is the formation of the signaling NO molecule. Cultivation of green plants under conditions of prolonged (4 days) darkness, a strong stress factor for photosynthesizing cells, decreased the activity of NR. Moreover, darkness induced significant elevation of the POX activity that was prevented by the addition of nitrate to the growth medium. It is proposed that the changes in light conditions result in the competition between nitrate- and ROS-metabolizing activities of POX in leaves, and a possible interaction between NR and POX controls the levels of NO and ROS in the leaf tissue.

Effects of high pressure on the accumulation of trehalose and glutathione in the Saccharomyces cerevisiae cells

The metabolism of trehalose, a marker of general physiological stress, and glutathione (GSH), another marker of oxidative stress marker, was examined in exponentially growing Saccharomyces cerevisiae cells after treatment with high pressure air. The growth of yeast cells was dramatically decreased under high pressure and the duration of stable growth was significantly shortened. Scanning electron microscopy showed that high pressure led to the disruption of membrane structure. Yeast cells were wrinkled or broken under higher pressure, indicating high pressure was a strong stress factor. The maximum yields of trehalose and GSH were obtained when the cells were cultured under 1.0 MPa pressure for 3 and 6 h, respectively. The increase of the production of trehalose and GSH indicated that trehalose and glutathione had protection effects under the stress of high pressure.

Effects of lifting date and storage time on changes in carbohydrate content and photosynthetic efficiency in three deciduous species

SummaryThe effect of lifting date and storage duration on the change in carbohydrate reserves during cold storage and the photosynthetic capacity after storage was examined in red-osier dogwood, common oak and silver birch of two genotypes ‘Asarum’ and ‘Halstenbeck’. Plants were grown at a ®eld site in southern Sweden and were lifted on two dates, 21 September and 30 November 1998. Plants were packed in closed plastic bags and kept in cold storage. Carbohydrate reserves were measured at lifting and after 8, 16 and 24 weeks of storage. Plants were removed from storage after 8, 12, 16, 20 and 24 weeks and were subsequently grown in a climate chamber. After four weeks, plants were assessed for mortality, die-back, growth and photosynthetic capacity, measured as chlorophyll fluorescence. Chlorophyll fluorescence indicated that lifting per se is a strong stress factor, as plants, independently of lifting date and storage duration, were stressed and had low photochemical efficiency in photosystem II. Further, the low efficiency was more pronounced in plants lifted early. Die-back appeared in early lifted plants of all species after 3–4 months of storage, except for silver birch ‘Asarum’. Carbohydrates in roots and shoots declined during storage in early lifted plants, but only in late lifted plants of roots and shoots of red-osier dogwood and shoots of common oak. Shoot growth decreased in early lifted red-osier dogwood plants, with longer storage. This study has shown that lifting date and storage duration are two strong stress factors, which have a detrimental effect on plant vitality, even if plants are stored in closed plastic bags.

Influence of time of lifting and storage on the potential photosynthetic efficiency in newly developed leaves of bare-root silver birch and common oak

Silver birch and common oak are known to be sensitive to standard practices in nurseries and they often show poor establishment when transplanted in urban areas. Lifting date and time in cold storage have a strong influence on stress tolerance and plant vitality. This study was carried out to assess the effect of lifting date and storage time on partial photosynthesis measured by chlorophyll fluorescence. Plants were grown at a field site in southern Sweden and were lifted on four occasions, with an interval of 4 weeks during autumn 1997, and were subsequently placed in cold storage for 90, 135 and 180 days. Chlorophyll fluorescence was measured with a pulse-amplified modulation fluorometer in three leaves from the main terminal shoot of three plants from each treatment after 4 weeks growth in a controlled environment room. Four fluorescence parameters were measured: F m, F 0, F v/ F m and yield. The results of the yield measurement during illumination, showed that the plants, independently of lifting date and time in storage, were stressed and had a low photosynthetic efficiency. All plants taken up on the two first lifting occasions and those lifted on the third and fourth occasions and stored for 90 and 135 days, and 90 days, respectively, had relatively low values in maximal quantum yield ( F v/ F m, measured after a dark period). The low F v/ F m was due to high values in F 0, which often indicates malfunction in the reaction centres of photosystem II. This study, together with previous studies, has shown that lifting and storage are strong stress factors for silver birch and common oak. These two events are normal nursery practice. Nurseries need to be aware of the stress effects and attempt to minimise stress by choosing appropriate lifting dates and storage regimes, and thereby minimising tree fatality or poor growth after transplanting.