[Predictive and prognostic factors of gastric cancer]

INTRODUCTION

Gastric cancer is a frequent malignant disease with poor prognosis. Most patients undergo only palliative treatment. Chemotherapy is another alternative but its effect differs in individual patients.

METHOD

This is retrospective study. We enrolled 54 patients (N=54) according to the inclusion criteria. We performed quantification of gene expression of selected genes and some microRNA from tumour tissue, which was used for the diagnosis. Statistical analysis of the data was performed.

RESULTS

We demonstrated a predictive value of gene expression of thynidylate synthase in tumour tissue for a therapeutic effect of chemotherapy based on 5-Fluorouracil or Capecitabine. At the same time, we demonstrated a predictive value of miR181, miR150, mir192 and miR342 microRNA levels from the tumour tissue. In addition, we succeeded to demonstrate a predictive value of miR221, miR224, miR520 and miR375 microRNA levels for a therapeutic effect of chemotherapy based on platinum derivates.

CONCLUSION

Thanks to the use of efficient therapy predictors, we can distinguish those patients who will profit from chemotherapy from patients where an effect cannot be expected. Thanks to personified oncology therapy the quality of life of some patients can be improved while reducing the costs of the therapy by avoiding inefficient chemotherapy. Only an early diagnosis of gastric cancer can reverse the adverse prognosis of patients with this disease.

KEY WORDS

gastric cancer - microRNA - prognostic markers - predictive markers.

[Chest Injury and its Surgical Treatment in Polytrauma Patients. Five-Year Experience]

PURPOSE OF THE STUDY Thoracic trauma, one of the most frequent injuries in patients with multiple traumata, is found in 50 to 80% of these patients and it is crucial for the patient's prognosis. It accounts for 25% of all death from polytraumatic injuries. The aim of this retrospective study was an analysis of the occurrence of chest injuries in polytrauma patients and their surgical treatment in the Trauma Centre or Department of Surgery of the University Hospital Pilsen in a five-year period. MATERIAL AND METHODS Patients with injuries meeting the definition of polytrauma and an Injury Severity Score (ISS) ≥16 were included. The demographic characteristics, mechanism of multiple trauma, ISS value and chest injury were recorded in each patient. The number of injured patients in each year of the study was noted. In the patients with chest injury, the type of injury and method of treatment were assessed. The therapy was further analysed including its timing. The number of deaths due to polytrauma involving chest injury, the cause of death and its time in relation to the patient's admission to the Trauma Centre were evaluated. RESULTS In the period 2010-14, 513 polytrauma patients were treated; of them 371 (72.3%) were men with an average age of 40.5 years. The most frequent cause of injury was a traffic accident (74%). The average ISS of the whole group was 35 points. Chest injury was diagnosed in 469 patients (91.4%) of whom only five (1.1%) had penetrating injury. Pulmonary contusion was most frequent (314 patients; 67%). A total of 212 patients with chest injury underwent surgery (45.2%); urgent surgery was performed in 143 (67.5%), acute surgery in 49 (23.1%) and delayed surgery in 63 (29.7%) patients. Chest drainage was the major surgical procedure used in the whole group. Of 61 patients who died, 52 had chest injury. In this subgroup the most frequent cause of death was decompensated traumatic shock (26 patients; 50%). In the whole group, 32 polytrauma patients died within 24 hours of injury (61.5%). CONCLUSIONS Chest injury, almost always blunt, is often diagnosed in polytrauma patients. A prevalent cause of multiple trauma is a traffic accident. Chest injury most frequently involves pulmonary contusion. Nearly half of chest injuries require surgery, of which 2/3 are urgent procedures. The procedure most frequently performed in polytrauma patients with chest injury is chest drainage and this is also a sufficient procedure in 75% of surgically treated patients.

KEY WORDS

polytrauma, chest injury, pulmonary contusion, surgical treatment, chest drainage.

[Thyroid carcinoma, ten-years file]

INTRODUCTION

Even though thyroid carcinoma has, in general, a good prognosis and low mortality rate, its incidence, especially the incidence of early forms of the disease has been growing.

METHOD

Retrospective analysis of the file of surgeries of documented thyroid carcinoma within the years of 2006-2015.

RESULTS

Thyroid carcinoma was recorded in 145 of 1820 patients operated for thyreopathy (8%); microcarcinoma (<10mm) was recorded in 64 cases (44.1%). The carcinoma was mostly detected accidentally during total thyroidectomy, which was in 70 cases (48.3%). The carcinoma was expected in 35 cases (24.1%) on the basis of prior puncture and total thyroidectomy was carried out straight away. Perioperative histology after hemithyroidectomy was requested in 31 cases (21.4%), and it was found positive only in 13 cases; thyroidectomy was finished in the second period in the other cases. Due to advanced carcinoma, tumour exploration/debulking was performed in 3 cases (2.1%) - for anaplastic carcinoma in all these cases. A permanent unilateral lesion - n. laryngeus recurrens - occurred in 3 cases (2.1%); a permanent bilateral lesion was recorded twice (1.4%).The most frequently manifested carcinoma was the papillary carcinoma in 114 patients (78.6%; 83 women/31 men; age of 1284 years; mean age of 50.6), the second most frequent carcinoma was the follicular carcinoma in 16 patients (11.0%; 15/1; 1969; 55.3), followed by the medullary carcinoma in 10 patients (6.9%; 6/4; 2576; 58.1). Anaplastic carcinoma was detected only in 4 cases (2.8%; 2/2; 6487; 75.5), and lymphoma of the thyroid gland occurred twice as well as Hürtle cell carcinoma.

CONCLUSION

Thyroid carcinoma is mostly found accidentally during surgery in the early phase of the disease. This proves the high quality of endocrinology care and the correctness of the tendency to indicate early surgical treatment of thyroidal pathology.Key words: thyroid carcinoma - thyroidectomy complications.

Effects of disturbance regime on carbohydrate reserves in meadow plants

Carbohydrate storage enables plants to tolerate both seasonally unfavourable conditions and recover from disturbance. Although short-term changes in storage levels due to disturbance are fairly well known, less is known about long-term changes in storage levels, especially in response to cessation of repeated disturbance. Additionally, whereas it is presumably the total amount (pool) of storage carbohydrate reserves that is of importance, typically carbohydrate concentrations are measured instead, as a proxy. We assessed changes in carbohydrate concentrations and pools in storage organs and changes in above- versus belowground biomass in response to mowing cessation in nine herbs from two meadows (dry and wet) at the (June) peak of vegetation development and the (October) growing season end 1 and 3 years after the change in the disturbance regime. We tested three hypotheses: (1) storage will increase with abandonment of mowing only in the first year after disturbance cessation, but not further increase subsequently, as high storage would hinder competitive ability; (2) storage will increase towards the end of the season in both disturbed and undisturbed plants; and (3) changes in carbohydrate concentrations are accurate predictors of changes in pools. Although species-specific changes in carbohydrate reserves occurred in the wet meadow, more general trends appeared in the dry meadow. There, plants accumulated higher carbohydrate reserves at the end of the season, especially in unmown plots. However, the reserves for plants in both disturbance regimes were the same at the growing season peak (June) in both examined years. The increase in storage of carbohydrates on unmown plots in October was manifested by increases of both storage organ biomass and carbohydrate concentration, whereas in mown plots, it was due only to increased carbohydrate concentration. Although concentrations and pools represent different aspects of plant carbohydrate economy, concentrations will represent short-term responses to changed disturbance regimes.

Bacterial community of cushion plant Thylacospermum ceaspitosum on elevational gradient in the Himalayan cold desert

Although bacterial assemblages are important components of soils in arid ecosystems, the knowledge about composition, life-strategies, and environmental drivers is still fragmentary, especially in remote high-elevation mountains. We compared the quality and quantity of heterotrophic bacterial assemblages between the rhizosphere of the dominant cushion-forming plant Thylacospermum ceaspitosum and its surrounding bulk soil in two mountain ranges (East Karakoram: 4850-5250 m and Little Tibet: 5350-5850 m), in communities from cold steppes to the subnival zone in Ladakh, arid Trans-Himalaya, northwest India. Bacterial communities were characterized by molecular fingerprinting in combination with culture-dependent methods. The effects of environmental factors (elevation, mountain range, and soil physico-chemical parameters) on the bacterial community composition and structure were tested by multivariate redundancy analysis and conditional inference trees. Actinobacteria dominate the cultivable part of community and represent a major bacterial lineage of cold desert soils. The most abundant genera were Streptomyces, Arthrobacter, and Paenibacillus, representing both r- and K-strategists. The soil texture is the most important factor for the community structure and the total bacteria counts. Less abundant and diverse assemblages are found in East Karakoram with coarser soils derived from leucogranite bedrock, while more diverse assemblages in Little Tibet are associated with finer soils derived from easily weathering gneisses. Cushion rhizosphere is in general less diverse than bulk soil, and contains more r-strategists. K-strategists are more associated with the extremes of the gradient, with drought at lowest elevations (4850-5000 m) and frost at the highest elevations (5750-5850 m). The present study illuminates the composition of soil bacterial assemblages in relation to the cushion plant T. ceaspitosum in a xeric environment and brings important information about heterotrophic bacteria in Himalayan soil.

Radioiodine treatment of Graves' disease - dose/response analysis

The clinical outcome of 153 Graves' disease patients treated with a wide dose range of radioactive iodine-131 (RAI) was analyzed retrospectively. Six to nine months after the first dose of RAI 60 patients (39%) were hypothyroid (or rather thyroxine-substituted) and 26 (17%) were euthyroid, while 67 patients (44%) did not respond properly: in 32 (21%) their antithyroid drug (ATD) dose could be reduced but not withdrawn (partial response) and 35 (23%) remained hyperthyroid or the same dose of ATD was necessary (no response). The outcome did not correspond significantly to the administered activity of RAI (medians 259, 259, 222, and 259 MBq for hypothyroid, euthyroid, partial, and no response subgroups, respectively), or the activity retained in the gland at 24 h (medians 127, 105, 143, and 152 MBq). The effect was, however, clearly, and in a stepwise pattern, dependent on initial thyroid volume (17, 26, 33 and 35 ml, P < 0.001) or activity per gram tissue retained at 24 h (6.02, 4.95, 4.75, and 4.44 MBq/g, P = 0.002). Also, higher residual level of thyrotoxicosis at the time of RAI treatment was connected with worse outcome. The dose-dependency of outcome was further analyzed. When our sample was divided into tertiles, according to the adjusted dose, the same modest success rates (47%) were seen in the lower and middle tertiles. However, doses higher than 5.88 MBq/g (the upper tertile) resulted in success rate of 75%. Finer division into decils has shown a threshold-like increase in cure rate between the 7th and the 8th decil. In the first 7 decils (doses ≤ 6 MBq/g) the complete response rate was 45 to 50%, in the 8th decil (6.0 to 7.8~MBq/g) it rose to 80% and was not further increased with increasing dose. Direct comparison of higher (> 6 MBq/g, cure rate 80%) and lower (≤ 6 MBq/g, cure rate 46%) doses gave highly significant difference (P < 0.001). With our dosing range we found a dose-dependent clinical outcome that suggests an optimum delivered dose near 6.5 MBq/g, resulting in successful treatment of ca 80% patients.

Prevalence of perfusion defects detected by stress 99mtechnetium sestamibi myocardial perfusion single-photon emission computed tomography in asymptomatic patients with breast cancer

AIM

The aim of the present study was to investigate myocardial perfusion in relation to disease history and laboratory parameters of atherosclerosis risk in asymptomatic patients with breast carcinoma.

PATIENTS AND METHODS

One-hundred and eighty-one patients with breast carcinoma were studied. Myocardial perfusion was assessed using single-photon emission computed tomography (SPECT) with 99mtechnetium sestamibi.

RESULTS

Perfusion defects were detected in 12 patients (7%). Higher body-mass index, increased concentrations of D-dimers, C-reactive protein, fibrinogen, glucose, triglycerides, and urinary albumin, a history of hypertension and of radiotherapy to the left chest wall were all associated with increased risk of perfusion defects. In a multivariate stepwise selection logistic regression model, body mass index, albuminuria and radiotherapy to the left hemithorax were significantly associated with the presence of perfusion defects.

CONCLUSION

In addition to other factors, treatment history may be associated with the presence of perfusion defects in patients with breast cancer.

Variation in stem anatomical characteristics of Campanuloideae species in relation to evolutionary history and ecological preferences

Background

The detailed knowledge of plant anatomical characters and their variation among closely related taxa is key to understanding their evolution and function. We examined anatomical variation in 46 herbaceous taxa from the subfamily Campanuloideae (Campanulaceae) to link this information with their phylogeny, ecology and comparative material of 56 woody tropical taxa from the subfamily Lobelioideae. The species studied covered major environmental gradients from Mediterranean to Arctic zones, allowing us to test hypotheses on the evolution of anatomical structure in relation to plant competitive ability and ecological preferences.

Methodology/Principal Findings

To understand the evolution of anatomical diversity, we reconstructed the phylogeny of studied species from nucleotide sequences and examined the distribution of anatomical characters on the resulting phylogenetic tree. Redundancy analysis, with phylogenetic corrections, was used to separate the evolutionary inertia from the adaptation to the environment. A large anatomical diversity exists within the Campanuloideae. Traits connected with the quality of fibres were the most congruent with phylogeny, and the Rapunculus 2 (“phyteumoid”) clade was especially distinguished by a number of characters (absence of fibres, pervasive parenchyma, type of rays) from two other clades (Campanula s. str. and Rapunculus 1) characterized by the dominance of fibres and the absence of parenchyma. Septate fibres are an exclusive trait in the Lobelioideae, separating it clearly from the Campanuloideae where annual rings, pervasive parenchyma and crystals in the phellem are characteristic features.

Conclusions/Significance

Despite clear phylogenetic inertia in the anatomical features studied, the ecological attributes and plant height had a significant effect on anatomical divergence. From all three evolutionary clades, the taller species converged towards similar anatomical structure, characterized by a smaller number of early wood vessels of large diameter, thinner cell-walls and alternate intervessel pits, while the opposite trend was found in small Arctic and alpine taxa. This supports the existing generalization that narrower vessels allow plants to grow in colder places where they can avoid freezing-induced embolism, while taller plants have wider vessels to minimize hydraulic resistance with their greater path lengths.

Methanogens at the top of the world: occurrence and potential activity of methanogens in newly deglaciated soils in high-altitude cold deserts in the Western Himalayas

Methanogens typically occur in reduced anoxic environments. However, in recent studies it has been shown that many aerated upland soils, including desert soils also host active methanogens. Here we show that soil samples from high-altitude cold deserts in the western Himalayas (Ladakh, India) produce CH4 after incubation as slurry under anoxic conditions at rates comparable to those of hot desert soils. Samples of matured soil from three different vegetation belts (arid, steppe, and subnival) were compared with younger soils originating from frontal and lateral moraines of receding glaciers. While methanogenic rates were higher in the samples from matured soils, CH4 was also produced in the samples from the recently deglaciated moraines. In both young and matured soils, those covered by a biological soil crust (biocrust) were more active than their bare counterparts. Isotopic analysis showed that in both cases CH4 was initially produced from H2/CO2 but later mostly from acetate. Analysis of the archaeal community in the in situ soil samples revealed a clear dominance of sequences related to Thaumarchaeota, while the methanogenic community comprised only a minor fraction of the archaeal community. Similar to other aerated soils, the methanogenic community was comprised almost solely of the genera Methanosarcina and Methanocella, and possibly also Methanobacterium in some cases. Nevertheless, ~10(3) gdw(-1) soil methanogens were already present in the young moraine soil together with cyanobacteria. Our results demonstrate that Methanosarcina and Methanocella not only tolerate atmospheric oxygen but are also able to survive in these harsh cold environments. Their occurrence in newly deglaciated soils shows that they are early colonizers of desert soils, similar to cyanobacteria, and may play a role in the development of desert biocrusts.

[Vesicouterine tiny fistula 8 years after a cesarean section - case report]

OBJECTIVE

To describe a case of uterovesical fistula after cesarean section with symptoms of vulvovaginal discomfort.

DESIGN

Case report.

SETTING

Department of Urology, Department of Obstetrics and Gynecology, University Hospital and Medical Faculty in Hradec Kralove, Charles University Prague.

CONCLUSION

Uterovesical fistula is a rare and unusual complication of cesarean section. Uterovesical fistula is tough to diagnose because of unspecific symptoms. A multidisciplinary approach is necessary for its successful diagnosis and treatment.

Community structure of soil phototrophs along environmental gradients in arid Himalaya

The well-developed biological soil crusts cover up to 40% of the soil surface in the alpine and subnival zones of the Tibetan Plateau, accounting for a vast area of Asia. We investigated the diversity and biomass of the phototrophic part (Cyanobacteria) of the microbial community inhabiting biological soil crusts and uncrusted soils in their surroundings on the elevation gradient of 5200-5900 m a.s.l. The influence of soil physico-chemical properties on phototrophs was studied. The ability of high-altitude phototrophs to fix molecular nitrogen was also determined under laboratory conditions. The biological soil crust phototroph community did not differ from that living in uncrusted soil in terms of the species composition, but the biomass is three-to-five times higher. An increasing trend in the cyanobacterial biomass from the biological soil crusts with elevation was observed, with the genera Nostoc spp., Microcoleus vaginatus and Phormidium spp. contributing to this increase. Based on the laboratory experiments, the highest nitrogenase activity was recorded in the middle elevations, and the rate of nitrogen fixation was not correlated with the cyanobacterial biomass.

Tree-rings mirror management legacy: dramatic response of standard oaks to past coppicing in Central Europe

BACKGROUND

Coppicing was one of the most important forest management systems in Europe documented in prehistory as well as in the Middle Ages. However, coppicing was gradually abandoned by the mid-20(th) century, which has altered the ecosystem structure, diversity and function of coppice woods.

METHODOLOGY/PRINCIPAL FINDINGS

Our aim was to disentangle factors shaping the historical growth dynamics of oak standards (i.e. mature trees growing through several coppice cycles) in a former coppice-with-standards in Central Europe. Specifically, we tried to detect historical coppicing events from tree-rings of oak standards, to link coppicing events with the recruitment of mature oaks, and to determine the effects of neighbouring trees on the stem increment of oak standards. Large peaks in radial growth found for the periods 1895-1899 and 1935-1939 matched with historical records of coppice harvests. After coppicing, the number of newly recruited oak standards markedly grew in comparison with the preceding or following periods. The last significant recruitment of oak standards was after the 1930s following the last regular coppicing event. The diameter increment of oak standards from 1953 to 2003 was negatively correlated with competition indices, suggesting that neighbouring trees (mainly resprouting coppiced Tilia platyphyllos) partly suppressed the growth of oak standards. Our results showed that improved light conditions following historical coppicing events caused significant increase in pulses of radial growth and most probably maintained oak recruitment.

CONCLUSIONS/SIGNIFICANCE

Our historical perspective carries important implications for oak management in Central Europe and elsewhere. Relatively intense cutting creating open canopy woodlands, either as in the coppicing system or in the form of selective cutting, is needed to achieve significant radial growth in mature oaks. It is also critical for the successful regeneration and long-term maintenance of oak populations.

Forest response to increasing typhoon activity on the Korean peninsula: evidence from oak tree-rings

The globally observed trend of changing intensity of tropical cyclones over the past few decades emphasizes the need for a better understanding of the effects of such disturbance events in natural and inhabited areas. On the Korean Peninsula, typhoon intensity has increased over the past 100 years as evidenced by instrumental data recorded from 1904 until present. We examined how the increase in three weather characteristics (maximum hourly and daily precipitation, and maximum wind speed) during the typhoon activity affected old-growth oak forests. Quercus mongolica is a dominant species in the Korean mountains and the growth releases from 220 individuals from three sites along a latitudinal gradient (33-38°N) of decreasing typhoon activity were studied. Growth releases indicate tree-stand disturbance and improved light conditions for surviving trees. The trends in release events corresponded to spatiotemporal gradients in maximum wind speed and precipitation. A high positive correlation was found between the maximum values of typhoon characteristics and the proportion of trees showing release. A higher proportion of disturbed trees was found in the middle and southern parts of the Korean peninsula where typhoons are most intense. This shows that the releases are associated with typhoons and also indicates the differential impact of typhoons on the forests. Finally, we present a record of the changing proportion of trees showing release based on tree-rings for the period 1770-1979. The reconstruction revealed no trend during the period 1770-1879, while the rate of forest disturbances increased rapidly from 1880 to 1979. Our results suggest that if typhoon intensity rises, as is projected by some climatic models, the number of forest disturbance events will increase thus altering the disturbance regime and ecosystem processes.

[Vascular reconstructions infections in the aortofemoral region]

INTRODUCTION

The incidence of prosthetic vascular graft infections in the aortofemoral region is reported at 0.6-3%. These complications are burdened with a high mortality of up to 50% and an amputation rate of up to 20%. The aim of our study was to give a complex view on the diagnostic and treatment possibilities of these serious complications of reconstructive vascular surgery.

MATERIAL AND METHODS

Prosthetic bypass grafts were performed in 1088 patients in the aortofemoral region between 2001-2011 at the Department of Surgery, Teaching Hospital and the Faculty of Medicine, Charles University, in Pilsen. 24 (2.2%) patients suffered from graft infection at various time intervals after primary vascular reconstruction. Clinical examination, computed tomography and positron emission tomography were the main diagnostic methods of vascular graft infection. "In situ" reconstructions dominated over extra-anatomic reconstructions. When the infection involved only the peripheral part of the prosthetic graft, a more conservative approach - local debridement and drainage - was used.

RESULTS

The mortality of the patients was 20.8%, high amputation rate 12.5%, and morbidity rate 58.3%, respectively. The average time of hospitalization in surviving patients was 46.5 days. Primary 30-day patency rate in "in situ" and extra-anatomic reconstructions was 100 and 60%, respectively.

CONCLUSION

Prosthetic vascular graft infections in the aortofemoral region require tailored multidisciplinary treatment approach in vascular centres. "In situ" reconstructions are the method of first choice. A more conservative approach in infections involving only the peripheral part of the vascular reconstruction has a positive treatment effect.

Communities of different plant diversity respond similarly to drought stress: experimental evidence from field non-weeded and greenhouse conditions

Accelerating rate of species loss has prompted researchers to study the role of species diversity in processes that control ecosystem functioning. Although negative impact of species loss has been documented, the evidence concerning its impact on ecosystem stability is still limited. Here, we studied the effects of declining species and functional diversity on plant community responses to drought in the field (open to weed colonization) and greenhouse conditions. Both species and functional diversity positively affected the average yields of field communities. However, this pattern was similar in both drought-stressed and control plots. No effect of diversity on community resistance, biomass recovery after drought and resilience was found because drought reduced biomass production similarly at each level of diversity by approximately 30%. The use of dissimilarity (characterized by Euclidean distance) revealed higher variation under changing environments (drought-stressed vs. control) in more diverse communities compared to less species-rich assemblages. In the greenhouse experiment, the effect of species diversity affected community resistance, indicating that more diverse communities suffered more from drought than species-poor ones. We conclude that our study did not support the insurance hypothesis (stability properties of a community should increase with species richness) because species diversity had an equivocal effect on ecosystem resistance and resilience in an environment held under non-weeded practice, regardless of the positive relationship between sown species diversity and community biomass production. More species-rich communities were less resistant against drought-stressed conditions than species-poor ones grown in greenhouse conditions.

Cushions of Thylacospermum caespitosum (Caryophyllaceae) do not facilitate other plants under extreme altitude and dry conditions in the north-west Himalayas

BACKGROUND

Cushion plants are commonly considered as keystone nurse species that ameliorate the harsh conditions they inhabit in alpine ecosystems, thus facilitating other species and increasing alpine plant biodiversity. A literature search resulted in 25 key studies showing overwhelming facilitative effects of different cushion plants and hypothesizing greater facilitation with increased environmental severity (i.e. higher altitude and/or lower rainfall). At the same time, emerging ecological theory alongside the cushion-specific literature suggests that facilitation might not always occur under extreme environmental conditions, and especially under high altitude and dryness.

METHODS

To assess these hypotheses, possible nursing effects of Thylacospermum caespitosum (Caryophyllaceae) were examined at extremely high altitude (5900 m a.s.l.) and in dry conditions (precipitation <100 mm year(-1)) in Eastern Ladakh, Trans-Himalaya. This is, by far, the highest site, and the second driest, at which the effects of cushions have been studied so far.

KEY RESULTS

In accordance with the theoretical predictions, no nursing effects of T. caespitosum on other alpine plants were detected. The number and abundance of species were greater outside cushions than within and on the edge of cushions. None of the 13 species detected was positively associated with cushions, while nine of them were negatively associated. Plant diversity increased with the size of the area sampled outside cushions, but no species-area relationship was found within cushions.

CONCLUSIONS

The results support the emerging theoretical prediction of restricted facilitative effects under extreme combinations of cold and dryness, integrating these ideas in the context of the ecology of cushion plants. This evidence suggests that cases of missing strong facilitation are likely to be found in other extreme alpine conditions.

Soil cyanobacterial and microalgal diversity in dry mountains of Ladakh, NW Himalaya, as related to site, altitude, and vegetation

Although phototrophic microbial communities are important components of soils in arid and semi-arid ecosystems around the world, the knowledge of their taxonomic composition and dependency on soil chemistry and vegetation is still fragmentary. We studied the abundance and the diversity of cyanobacteria and eukaryotic microalgae along altitudinal gradients (3,700-5,970 m) at four sites in the dry mountains of Ladakh (Little Tibet, Zanskar Mountains, and Eastern Karakoram), using epifluorescence. The effects of environmental factors (altitude, mountain range, and vegetation type) on soil physico-chemical parameters (pH; texture; organic matter, nitrogen, ammonia, and phosphorus contents; and concentration of chlorophylls and carotenoids) and on the composition and biovolume of phototrophs were tested by multivariate redundancy analysis and variance partitioning. Phototrophs were identified in all collected samples, and phototroph biovolume ranged from 0.08 to 0.32 mm(3) g(-1) dry weight. The dominant component was cyanobacteria, which represented 70.9% to 98.6% of the biovolume. Cyanobacterial species richness was low in that only 28 morphotypes were detected. The biovolume of Oscillatoriales consisted mainly of Phormidium spp. and Microcoleus vaginatus. The environmental factors accounted for 43.8% of the total variability in microbial and soil data, 20.6% of which was explained solely by mountain range, 7.0% by altitude, and 8.4% by vegetation type. Oscillatoriales prevailed in alpine meadows (which had relatively high organic matter and fine soil texture), while Nostocales dominated in the subnival zone and screes. Eukaryotic microalgae together with cyanobacteria in the order Chroococcales were mostly present in the subnival zone. We conclude that the high elevation, semiarid, and arid soils in Ladakh are suitable habitats for microbial phototrophic communities and that the differences in these communities are associated with site, altitude, and vegetation type.

Effect of abandonment and plant classification on carbohydrate reserves of meadow plants

We studied the effect of cessation of management on carbohydrate reserves of plants in meadows with different environmental characteristics and plant composition. We recorded storage carbohydrates and seasonal changes for 40 plant species. We asked whether there are differences in responses of carbohydrate reserves in forbs versus graminoids and in plants storing starch versus plants storing osmotically active carbohydrates. We analysed belowground organs before the meadows were mown and at the end of the vegetation season in mown versus recently abandoned plots. Whereas starch and fructans were widely distributed, raffinose family oligosaccharides were the main carbohydrate reserves of the Lamiaceae and Plantago lanceolata. Properties of carbohydrate reserves differed between forbs and graminoids but no difference was found between plants storing starch versus osmotically active carbohydrates. Graminoids had lower carbohydrate concentrations than forbs. We observed a positive effect of mowing on carbohydrate concentrations of graminoids in the dry, calcium-rich meadow and higher seasonal fluctuations of these values in the acid, wet meadow, suggesting that local factors and/or the species pool affect carbohydrate reserves. Despite local conditions, graminoids represent a distinct functional group in meadows from the point of view of their storage economy. We suggest that as well as growth, storage processes should also be considered for understanding the functioning of meadow plant communities.