Microplastic ingestion affects hydrogen production and microbiomes in the gut of the terrestrial isopod Porcellio scaber

Microplastic (MP) is an environmental burden and enters food webs via ingestion by macrofauna, including isopods (Porcellio scaber) in terrestrial ecosystems. Isopods represent ubiquitously abundant, ecologically important detritivores. However, MP-polymer specific effects on the host and its gut microbiota are unknown. We tested the hypothesis that biodegradable (polylactic acid [PLA]) and non-biodegradable (polyethylene terephthalate [PET]; polystyrene [PS]) MPs have contrasting effects on P. scaber mediated by changes of the gut microbiota. The isopod fitness after an 8-week MP-exposure was generally unaffected, although the isopods showed avoidance behaviour to PS-food. MP-polymer specific effects on gut microbes were detected, including a stimulation of microbial activity by PLA compared with MP-free controls. PLA stimulated hydrogen emission from isopod guts, while PET and PS were inhibitory. We roughly estimated 107  kg year-1 hydrogen emitted from the isopods globally and identified their guts as anoxic, significant mobile sources of reductant for soil microbes despite the absence of classical obligate anaerobes, likely due to Enterobacteriaceae-related fermentation activities that were stimulated by lactate generated during PLA-degradation. The findings suggest negative effects of PET and PS on gut fermentation, modulation of important isopod hydrogen emissions by MP pollution and the potential of MP to affect terrestrial food webs.

Biodegradable polymers boost reproduction in the earthworm Eisenia fetida

Microplastic contamination in soil has become a global environmental threat as it adversely affects terrestrial organisms like earthworms as well as soil properties. Especially biodegradable polymers have recently been used as an alternative to conventional polymer types, although their impact remains poorly understood. Thus, we studied the effect of conventional (polystyrene: PS, polyethylene terephthalate: PET, polypropylene: PP) versus aliphatic polyesters classified as biodegradable polymers (poly-(l-lactide): PLLA, polycaprolactone: PCL) on the earthworm Eisenia fetida and soil properties (pH and cation exchange capacity). We addressed direct effects on the weight gain and reproductive success of E. fetida, and indirect effects, like changes in the gut microbial composition as well as the production of short-chain fatty acids by the gut microbiota. Earthworms were exposed for eight weeks in an artificial soil amended with two environmentally relevant concentrations (1 % and 2.5 % (w/w)) of the different microplastic types. PLLA and PCL boosted the number of cocoons produced by 135 % and 54 % respectively. Additionally, exposure to these two polymers increased number of hatched juveniles, changed gut microbial beta-diversity, and increased the production of the short chain fatty acid lactate compared to the control treatments. Interestingly, we also found a positive effect of PP on the earthworm's bodyweight and reproductive success. The interaction of microplastic and earthworms decreased soil pH by about 1.5 units in the presence of PLLA and PCL. No polymer effect on the cation exchange capacity of soil was found. In general, neither the presence of conventional nor biodegradable polymers had any adverse effects on any of the studied endpoints. Our results suggest that the effects of microplastic highly depend on the polymer type, and that the degradation of biodegradable polymers might be enhanced in the gut of earthworms, which implies that they may use biodegradable polymers as a potential carbon source.

Comparison of fitness effects in the earthworm Eisenia fetida after exposure to single or multiple anthropogenic pollutants

Terrestrial ecosystems are exposed to many anthropogenic pollutants. Non-target effects of pesticides and fertilizers have put agricultural intensification in the focus as a driver for biodiversity loss. However, other pollutants, such as heavy metals, particulate matter, or microplastic also enter the environment, e.g. via traffic and industrial activities in urban areas. As soil acts as a potential sink for such pollutants, soil invertebrates like earthworms may be particularly affected by them. Under natural conditions soil invertebrates will likely be exposed to combinations of pollutants simultaneously, which may result in stronger negative effects if pollutants act synergistically. Within this work we study how multiple pollutants affect the soil-dwelling, substrate feeding earthworm Eisenia fetida. We compared the effects of the single stressors, polystyrene microplastic fragments, polystyrene fibers, brake dust and carbon black, with the combined effect of these pollutants when applied as a mixture. Endpoints measured were survival, increase in body weight, reproductive fitness, and changes in three oxidative stress markers (glutathione S-transferase, catalase and malondialdehyde). We found that among single pollutant treatments, brake dust imposed the strongest negative effects on earthworms in all measured endpoints including increased mortality rates. Sub-lethal effects were found for all pollutants. Exposing earthworms to all four pollutants simultaneously led to effects on mortality and oxidative stress markers that were smaller than expected by the respective null models. These antagonistic effects are likely a result of the adsorption of toxic substances found in brake dust to the other pollutants. With this study we show that effects of combinations of pollutants cannot necessarily be predicted from their individual effects and that combined effects will likely depend on identity and concentration of the pollutants.

In vitro cultivation of primary intestinal cells from Eisenia fetida as basis for ecotoxicological studies

The earthworm Eisenia fetida is a commonly used model organism for unspecific soil feeders in ecotoxicological studies. Its intestinal cells are the first to encounter possible pollutants co-ingested by the earthworm, which makes them prime candidates for studies of toxic effects of environmental pollutants on the cellular as compared to the organismic level. In this context, the aim of this study was to demonstrate the suitability of preparations of primary intestinal E. fetida cells for in vitro ecotoxicological studies. For this purpose, a suitable isolation and cultivation protocol was established. Cells were isolated directly from the intestine, maintaining >85% viability during subsequent cultivations (up to 144 h). Exposure to established pollutants and soil elutriates comprising silver nanoparticles and metal ions (Cu²⁺, Cd²⁺) induced a significant decrease in the metabolic activity of the cells. In case of microplastic particles (MP particles), namely 0.2, 0.5, 2.0, and 3.0 µm diameter polystyrene (PS) beads as well as 0.5 and 2.0 µm diameter polylactic acid (PLA) beads, no active uptake was observed. Slight positive as well as negative dose and size dependent effects on the metabolism were seen, which to some extent might correlate with effects on the organismic level.

Individual vs. Combined Short-Term Effects of Soil Pollutants on Colony Founding in a Common Ant Species

Insects are integral to terrestrial life and provide essential ecosystem functions such as pollination and nutrient cycling. Due to massive declines in insect biomass, abundance, or species richness in recent years, the focus has turned to find their causes. Anthropogenic pollution is among the main drivers of insect declines. Research addressing the effects of pollutants concentrates on aquatic insects and pollinators, despite the apparent risk of contaminated soils. Pollutants accumulating in the soil might pose a significant threat because concentrations tend to be high and different pollutants are present simultaneously. Here, we exposed queens of the black garden ant Lasius niger at the colony founding stage to different concentrations and combinations of pollutants (brake dust, soot, microplastic particles and fibers, manure) to determine dose-dependent effects and interactions between stressors. As proxies for colony founding success, we measured queen survival, the development time of the different life stages, the brood weight, and the number of offspring. Over the course of the experiment queen mortality was very low and similar across treatments. Only high manure concentrations affected the colony founding success. Eggs from queens exposed to high manure concentrations took longer to hatch, which resulted in a delayed emergence of workers. Also, fewer pupae and workers were raised by those queens. Brake dust, soot and plastic particles did not visibly affect colony founding success, neither as single nor as multiple stressors. The application of manure, however, affected colony founding in L. niger negatively underlining the issue of excessive manure application to our environment. Even though anthropogenic soil pollutants seem to have little short-term effects on ant colony founding, studies will have to elucidate potential long-term effects as a colony grows.

[Chimeric antigen receptors (CARs): universal tools in adoptive cell therapy]

BACKGROUND

The observation that tumor-infiltrating lymphocytes (TIL) after ex vivo amplification can control tumors in the long term led to the concept of redirecting patients' cytolytic T‑cells by a receptor with defined specificity against the tumor.

OBJECTIVES

Development of a recombinant receptor-signal molecule (chimeric antigen receptor, CAR) to increase selectivity and enhance anti-tumor immunity.

METHODS

Description of a prototype CAR, overview of the modular composition and further development of CAR technology for use in adoptive immune cell therapy.

RESULTS

Intensive research over the last two decades has shown how CAR-mediated T‑cell activation is influenced by factors such as binding affinity, the epitope of the target antigen, its expression density and accessibility on the tumor cells, as well as by the signaling domains and their combination to induce T‑cell activation. The quality and duration of the T‑cell response can be specifically modulated by modifying the modular composition of the CAR; CAR T‑cells can act as "biopharmaceutical factories" (T-cells redirected for unrestricted cytokine-mediated killing, TRUCK) in the tissue by CAR-mediated release of transgenic therapeutic proteins.

CONCLUSION

Adoptive CAR T‑cell therapy has shown clinical efficacy in the treatment of hematological malignancies; the treatment of solid tumors, however, is more challenging. Allogeneic CAR T‑cell technology is aimed at generating "off-the-shelf" CAR T‑cells that are accessible for a large number of patients. A further promising approach is the use of CAR T‑cells for other therapeutic applications such as the treatment of autoimmune diseases.

Origin, behaviour, and genetics of reproductive workers in an invasive ant

Background

Worker reproduction has an important influence on the social cohesion and efficiency of social insect colonies, but its role in the success of invasive ants has been neglected. We used observations of 233 captive colonies, laboratory experiments, and genetic analyses to investigate the conditions for worker reproduction in the invasive Anoplolepis gracilipes (yellow crazy ant) and its potential cost on interspecific defence. We determined the prevalence of worker production of males and whether it is triggered by queen absence; whether physogastric workers with enlarged abdomens are more likely to be reproductive, how normal workers and physogastric workers compare in their contributions to foraging and defence; and whether worker-produced males and males that could have been queen- or worker-produced differ in their size and heterozygosity.

Results

Sixty-six of our 233 captive colonies produced males, and in 25 of these, some males could only have been produced by workers. Colonies with more workers were more likely to produce males, especially for queenless colonies. The average number of days between the first appearance of eggs and adult males in our colonies was 54.1 ± 10.2 (mean ± SD, n = 20). In our laboratory experiment, queen removal triggered an increase in the proportion of physogastric workers. Physogastric workers were more likely to have yolky oocytes (37–54.9%) than normal workers (2–25.6%), which is an indicator of fertile or trophic egg production. Physogastric workers were less aggressive during interspecific aggression tests and foraged less than normal workers. The head width and wing length of worker-produced males were on average 4.0 and 4.3% greater respectively than those of males of undetermined source. Our microsatellite DNA analyses indicate that 5.5% of worker-produced males and 14.3% of males of undetermined source were heterozygous, which suggests the presence of diploid males and/or genetic mosaics in A. gracilipes.

Conclusions

Our experimental work provides crucial information on worker reproduction in A. gracilipes and its potential cost to colony defence. The ability of A. gracilipes workers to produce males in the absence of queens may also contribute to its success as an invasive species if intranidal mating can take place between virgin queens and worker-produced males.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12983-021-00392-2.

Effects of Dance Movement Therapy on Adult Patients with Autism Spectrum Disorder: A Randomized Controlled Trial

This study examines the effects of dance movement therapy (DMT) on empathy for adults with autism spectrum disorder (ASD). DMT based on the embodiment approach offers body-centered interventions, such as mirroring techniques, to address the needs of ASD patients. Accordingly, findings of a feasibility study suggest that DMT may be an effective approach for clients on the ASD spectrum. The present study is a randomized controlled trial that was conducted as a multicenter study within the framework of the EU-funded research project TESIS (Toward an Embodied Science of Intersubjectivity), and employed a two-factorial between-subject design. The treatment group (n = 35) participated in a 10-week manualized DMT intervention, whereas the control group (n = 22) received treatment only after a waiting period. Empathy, measured with the Cognitive and Emotional Empathy Questionnaire (CEEQ), was the main variable of interest, analyzed by a repeated measures analysis of variance. In order to also include incomplete data cases, we used the expectation-maximization algorithm for missing data estimation. Results suggest no significant changes in overall empathy between groups. We discuss the results and limitations, as well as future research options.

A new microscopic method to analyse desiccation-induced volume changes in aeroterrestrial green algae

Aeroterrestrial green algae are exposed to desiccation in their natural habitat, but their actual volume changes have not been investigated. Here, we measure the relative volume reduction (RVRED ) in Klebsormidium crenulatum and Zygnema sp. under different preset relative air humidities (RH). A new chamber allows monitoring RH during light microscopic observation of the desiccation process. The RHs were set in the range of ∼4 % to ∼95% in 10 steps. RVRED caused by the desiccation process was determined after full acclimation to the respective RHs. In K. crenulatum, RVRED (mean ± SE) was 46.4 ± 1.9%, in Zygnema sp. RVRED was only 34.3 ± 2.4% at the highest RH (∼95%) tested. This indicates a more pronounced water loss at higher RHs in K. crenulatum versus Zygnema sp. By contrast, at the lowest RH (∼4%) tested, RVRED ranged from 75.9 ± 2.7% in K. crenulatum to 83.9 ± 2.2% in Zygnema sp. The final volume reduction is therefore more drastic in Zygnema sp. These data contribute to our understanding of the desiccation process in streptophytic green algae, which are considered the closest ancestors of land plants.

Photosynthetic efficiency, desiccation tolerance and ultrastructure in two phylogenetically distinct strains of alpine Zygnema sp. (Zygnematophyceae, Streptophyta): role of pre-akinete formation

Two newly isolated strains of green algae from alpine regions were compared physiologically at different culture ages (1, 6, 9 and 15 months). The strains of Zygnema sp. were from different altitudes ('Saalach' (S), 440 m above sea level (a.s.l.), SAG 2419 and 'Elmau-Alm' (E-A), 1,500 m a.s.l., SAG 2418). Phylogenetic analysis of rbcL sequences grouped the strains into different major subclades of the genus. The mean diameters of the cells were 23.2 μm (Zygnema S) and 18.7 μm (Zygnema E-A) but were reduced significantly with culture age. The photophysiological response between the strains differed significantly; Zygnema S had a maximal relative electron transport rate (rETR max) of 103.4 μmol electrons m(-2) s(-1), Zygnema E-A only 61.7 μmol electrons m(-2) s(-1), and decreased significantly with culture age. Both strains showed a low-light adaption and the absence of strong photoinhibition up to 2,000 μmol photons m(-2) s(-1). Photosynthetic oxygen production showed similar results (P max Zygnema S, 527.2 μmol O2 h(-1) mg(-1) chlorophyll (chl.) a, Zygnema E-A, 390.7 μmol O2 h(-1) mg(-1) chl. a); the temperature optimum was at 35 °C for Zygnema S and 30 °C for Zygnema E-A. Increasing culture age moreover leads to the formation of pre-akinetes, which accumulate storage products as revealed by light and transmission electron microscopy. Desiccation at 84 % relative air humidity (RH) lead to a reduction of the effective quantum yield of photosystem II (PSII) (ΔFv/Fm') to zero between 90 to 120 min (Zygnema S) and between 30 to 60 min (Zygnema E-A), depending on the culture age. A partial recovery of ΔFv/Fm' was only observed in older cultures. We conclude that pre-akinetes are crucial for the aeroterrestrial lifestyle of Zygnema.

The weal and woe of costimulation in the adoptive therapy of cancer with chimeric antigen receptor (CAR)-redirected T cells

Adoptive cell therapy has shown impressive efficacy to combat cancer in early phase clinical trials, in particular when T cells engineered to specifically target tumor cells were applied. The patient's T cells are genetically equipped with a chimeric antigen receptor (CAR) which allows them to be redirected in a predefined manner towards virtually any target; by using an antibody-derived domain for binding, CAR T cells can be redirected in a major histocompatibility complex (MHC) dependent and independent fashion. The CAR also provides the stimuli required to induce and maintain T cell activation. Recent clinical data sustain the notion that strong costimulation in conjunction with the primary activation signal is crucial for lasting therapeutic efficacy of CAR T cells. However, costimulation is a double-edged sword and the impact of the individual costimuli to optimize T cell activation is still under debate; some general rules are emerging. The review summarizes how costimulation modulates, improves and prolongs the redirected anti-tumor T cell response and how the same costimulatory signals may contribute to unintended side effects including "cytokine storm" and T cell repression. Upcoming strategies to break the activation/repression circle by using CAR's with modified costimulatory signals are also discussed.

Spherical particles of halophilic archaea correlate with exposure to low water activity--implications for microbial survival in fluid inclusions of ancient halite

Viable extremely halophilic archaea (haloarchaea) have been isolated from million-year-old salt deposits around the world; however, an explanation of their supposed longevity remains a fundamental challenge. Recently small roundish particles in fluid inclusions of 22 000- to 34 000-year-old halite were identified as haloarchaea capable of proliferation (Schubert BA, Lowenstein TK, Timofeeff MN, Parker MA, 2010, Environmental Microbiology, 12, 440-454). Searching for a method to produce such particles in the laboratory, we exposed rod-shaped cells of Halobacterium species to reduced external water activity (a(w)). Gradual formation of spheres of about 0.4 μm diameter occurred in 4 M NaCl buffer of a(w) ≤ 0.75, but exposure to buffered 4 M LiCl (a(w) ≤ 0.73) split cells into spheres within seconds, with concomitant release of several proteins. From one rod, three or four spheres emerged, which re-grew to normal rods in nutrient media. Biochemical properties of rods and spheres were similar, except for a markedly reduced ATP content (about 50-fold) and an increased lag phase of spheres, as is known from dormant bacteria. The presence of viable particles of similar sizes in ancient fluid inclusions suggested that spheres might represent dormant states of haloarchaea. The easy production of spheres by lowering a(w) should facilitate their investigation and could help to understand the mechanisms for microbial survival over geological times.

Evolution of public attitudes about mental illness: a systematic review and meta-analysis

OBJECTIVE

To explore whether the increase in knowledge about the biological correlates of mental disorders over the last decades has translated into improved public understanding of mental illness, increased readiness to seek mental health care and more tolerant attitudes towards mentally ill persons.

METHOD

A systematic review of all studies on mental illness-related beliefs and attitudes in the general population published before 31 March 2011, examining the time trends of attitudes with a follow-up interval of at least 2 years and using national representative population samples. A subsample of methodologically homogeneous studies was further included in a meta-regression analysis of time trends.

RESULTS

Thirty-three reports on 16 studies on national time trends met our inclusion criteria, six of which were eligible for a meta-regression analysis. Two major trends emerged: there was a coherent trend to greater mental health literacy, in particular towards a biological model of mental illness, and greater acceptance of professional help for mental health problems. In contrast, however, no changes or even changes to the worse were observed regarding the attitudes towards people with mental illness.

CONCLUSION

Increasing public understanding of the biological correlates of mental illness seems not to result in better social acceptance of persons with mental illness.

239 A NOVEL PIG MODEL OF CYSTIC FIBROSIS GENERATED BY SEQUENTIAL TARGETING OF CFTR BY BACTERIAL ARTIFICIAL CHROMSOME VECTORS

Cystic fibrosis (CF), the most common inherited disease in the Caucasian population, is caused by mutations of the CFTR gene, coding for an anion channel responsible for chloride movement, determining transepithelial salt transport, fluid flow and ion concentrations. Cystic fibrosis is determined by chronic lung disease, marked by airway surface dehydration, reduced mucus clearance and increased mucus obstruction, impaired bacterial killing and inflammation and continuous destruction of the lung tissue. The lack of suitable CF mouse models has so far impeded the understanding of disease mechanisms and the development of novel therapies. Recently, a pig model reflecting the main hallmarks of the human disease in the respiratory, gastrointestinal and genital tracts has been reported (Rogers et al. 2008 Science 321, 1837–1841). In the present study, we generated a new CF pig model by disrupting the CFTR gene using an approach that differs in 3 major aspects from the previously published model: (1) gene targeting was achieved using a modified bacterial artificial chromosome (BAC) vector; (2) transcription of the CFTR gene was completely prevented; and (3) homozygous CFTR mutant pigs were derived by nuclear transfer from cells in which both alleles were inactivated by sequential BAC targeting. We characterised 2 cloned litters with a total of 13 piglets (including 4 stillborns). All piglets showed a characteristic CF multi-organ disease with severe meconium ileus, microcolon, microgallbladder, hypoplasia of the exocrine pancreas, congenital aplasia of the vas deferens and malformations of the trachea. In contrast to the recently published CF pig, where the majority of the intestinal obstructions occurred proximal to the ileocecal junction, we found obstructions exclusively distal to this site. We thus present a novel pig model for CF that reflects the main hallmarks of the human disease. It confirms the suitability of the CFTR mutant pig for cystic fibrosis research and increases the availability of CF models for molecular and translational CF research. The help by Prof. K. Heinritzi and his team from the Pig Clinic, LMU Munich, is gratefully acknowledged. This study was supported by Mukoviszidose e.V.

The loss of sadness: the public's view

OBJECTIVE

With the exception of bereavement, the diagnosis of major depressive disorder in the DSM-IV does not take into account the context in which the symptoms occur. Recent criticism has maintained that common sense suggests making a distinction between depression as mental disorder and sorrow as 'normal' reaction to social stress. This study sets out to investigate whether the public does in fact make this distinction.

METHOD

In spring 2009, a population-based survey was conducted by phone in the city of Vienna (n = 1205). A fully structured interview was carried out which began with the presentation of a vignette describing a diagnostically unlabeled case of depression, with or without provision of information about preceding stressful life events.

RESULTS

Respondents presented with vignettes containing information on loss events were less likely to define depressive symptoms as indication of mental illness. They were also not as willing to recommend professional help. And if they were, they tended to less frequently recommend seeking help from someone with a medical background.

CONCLUSION

In contrast to the conceptualization in the DSM-IV, the public tends to perceive depressive symptoms differently depending on the context in which they occur.

Cytoarchitecture of the desiccation-tolerant green alga Zygogonium ericetorum

In this study, the filamentous green alga Zygogonium ericetorum (Zygnematales, Chlorophyta), collected at its natural habitat in the high alps, was investigated by light, scanning, and transmission electron microscopy. The field samples were separated into a moist fraction when wetted by splattering water of a nearby spring or a desiccated one when visually dried out. Light microscopy demonstrated a purple pigmentation of the sun-exposed upper layers, the central position of the nucleus, and the starch content in the pyrenoids. The smooth surface of the cells occasionally covered with fungal hyphae was shown by scanning electron microscopy. The cytoarchitecture of moist cells revealed many vacuoles and only a thin cytoplasmic area surrounding the two chloroplasts. The secondary cell walls of older cells were up to 4 microm thick. Organelle membranes as well as thylakoid membranes occasionally showed an inversion of contrast. In the chloroplasts, distinct areas with granular content surrounding the pyrenoids were detected. Within the cytoplasm, electron-dense particles with electron-translucent crystalloid structures were observed. When desiccated samples were investigated, the vacuoles and cytoplasmatic portions appeared destroyed, whereas nucleus and chloroplasts generally remained intact. The thylakoid membranes of desiccated samples showed lumen dilatations and numerous plastoglobules. Water-soluble extracts were separated by high-pressure liquid chromatography that revealed two major compounds with UV-absorbing capacities.

Cell morphology, ultrastructure, and calcification pattern of Oocardium stratum, a peculiar lotic desmid

Cell morphology and ultrastructure of the desmid Oocardium stratum and its habitat conditions in two limestone-precipitating spring habitats in the Alps were studied. In spite of specific cell geometry, we found ultrastructural features (nucleus with nucleolus, Golgi apparatus, chloroplast structure, lipid bodies, cell wall texture) closely related to other desmids. The type of the mucilage pore apparatus perforating in high densities extended areas of the cell wall of Oocardium is of the Cosmarium type. Oocardium contrasts to Cosmarium by a peculiar bilateral cell geometry (lateral sphenoid shape) which is combined with a dislocated nucleus. Although the cell features of Oocardium did not differ between the two habitats, different calcification types (rhombohedral calcite versus fascicular-fibrous calcite) and calcification intensities were recorded. The spatial positioning and extension of the Oocardium niches differed considerably between the two springs in spite of high CO(2) oversaturation at both sites.

Extreme hyponatremia in an infant with congenital adrenal hypoplasia due to a novel NR0B1 (DAX-1) mutation

BACKGROUND

Extreme hyponatremia (<105 mmol/l) has rarely been reported in infants. It is potentially life-threatening and requires intensive care treatment.

PATIENT

We report on a male infant with absence of weight gain from birth to day 33 of life despite adequate nutrition. On admission serum sodium and potassium were 104 and 5.9 mmol/L respectively. The infant's physical status revealed dehydration, but normal activity with no apparent neurological, circulatory or respiratory impairment.

MAIN RESULTS

Global adrenocortical insufficiency was diagnosed and treated with hormonal substitution in addition to intravenous application of fluid, glucose and electrolytes. The rise of serum sodium was carefully monitored and adjusted to a target rate of 0.5 mmol/L/h. X-linked adrenal hypoplasia congenita (X-AHC) was confirmed by the identification of a novel nonsense NR0B1 (DAX-1) mutation (W236X).

CONCLUSIONS

X-AHC in infants may present as failure to thrive despite adequate nutrition. Extreme hyponatremia may be associated with little symptoms if developing slowly. Rehydration and slow correction of serum sodium with solutions containing less sodium than normal saline is essential.

[Malassezia furfur colonising the respiratory tract of mechanically ventilated neonates]

BACKGROUND

Ventilated neonates are prone to acquire ventilator-associated pneumonia (VAP). Consequently early diagnosis of pneumonia is required. Beside bacteria, fungi are suspected as a cause of VAP. However, fungal colonisation and infection of the lung have not been studied systematically. The purpose of this study was to evaluate pulmonary fungal colonisation in ventilated neonates and premature infants.

MATERIALS AND METHODS

187 tracheal aspirates (TA) from 29 ventilated neonates (23-35 weeks gestational age) were investigated. TAs were evaluated microscopically and by culture. Data were matched with clinical signs of VAP or sepsis.

RESULTS

Candida species were not detected in TA or culture. In contrast, Malassezia furfur (Mf), a lipophilic fungus, was detected from the 10th, 21st and 31st postnatal days onwards in TAs of 3 out of 17 extremely prematures (gestational age at birth < 25 weeks). The presence of Mf was associated with clinical deterioration either immediately or a few days after the first positive Mf smear. Topic steroids were more frequently applied to Mf-positive ELBW infants (p = 0.03). In vitro, natural surfactant was demonstrated to be a sufficient substrate for Mf in culture.

CONCLUSION AND DISCUSSION

This is the first report on Mf lung colonisation of ELBWI during mechanical ventilation. Because Mf is generally not detected in standard cultures it appears to be an overlooked, potentially pathogenic fungus in prematures. Mf must be considered in the differential diagnosis of VAP in ELBWI exposed to topical steroids, especially when natural surfactant was administered.

Investigating cytoskeletal function in chloroplast protrusion formation in the arctic-alpine plant Oxyria digyna

Arctic and alpine plants like Oxyria digyna have to face enhanced environmental stress. This study compared leaves from Oxyria digyna collected in the Arctic at Svalbard (78 degrees N) and in the Austrian Alps (47 degrees N) at cellular, subcellular, and ultrastructural levels. Oxyria digyna plants collected in Svalbard had significantly thicker leaves than the samples collected in the Austrian Alps. This difference was generated by increased thickness of the palisade and spongy mesophyll layers in the arctic plants, while epidermal cells had no significant size differences between the two habitats. A characteristic feature of arctic, alpine, and cultivated samples was the occurrence of broad stroma-filled chloroplast protrusions, 2 - 5 microm broad and up to 5 microm long. Chloroplast protrusions were in close spatial contact with other organelles including mitochondria and microbodies. Mitochondria were also present in invaginations of the chloroplasts. A dense network of cortical microtubules found in the mesophyll cells suggested a potential role for microtubules in the formation and function of chloroplast protrusions. No direct interactions between microtubules and chloroplasts, however, were observed and disruption of the microtubule arrays with the anti-microtubule agent oryzalin at 5 - 10 microM did not alter the appearance or dynamics of chloroplast protrusions. These observations suggest that, in contrast to studies on stromule formation in Nicotiana, microtubules are not involved in the formation and morphology of chloroplast protrusions in Oxyria digyna. The actin microfilament-disrupting drug latrunculin B (5 - 10 microM for 2 h) arrested cytoplasmic streaming and altered the cytoplasmic integrity of mesophyll cells. However, at the ultrastructural level, stroma-containing, thylakoid-free areas were still visible, mostly at the concave sides of the chloroplasts. As chloroplast protrusions were frequently found to be mitochondria-associated in Oxyria digyna, a role in metabolite exchange is possible, which may contribute to an adaptation to alpine and arctic conditions.

Design and construction of a new temperature-controlled chamber for light and confocal microscopy under monitored conditions: biological application for plant samples

A new light microscope-temperature-controlled chamber (LM-TCC) has been constructed. The special feature of the light microscope-temperature-controlled chamber is the Peltier-element temperature control of a specimen holder for biological samples, with a volume capacity of 1 mL. This system has marked advantages when compared to other approaches for temperature-controlled microscopy. It works in a temperature range of -10 degrees C to +95 degrees C with an accuracy of +/-0.1 degrees C in the stationary phase. The light microscope-temperature-controlled chamber allows rapid temperature shift rates. A maximum heating rate of 12.9 degrees C min(-1) and a maximum cooling rate of 6.0 degrees C min(-1) are achieved with minimized overshoots (<or=1.9 degrees C). This machinery operates at low cost and external coolants are not required. Especially with samples absorbing irradiation strongly, temperature control during microscopy is necessary to avoid overheating of samples. For example, leaf segments of Ficaria verna exposed to 4500 micromol photons m(-2) s(-1) in a standard microscopic preparation show a temperature increase (deltaT) of 18.0 degrees C, whereas in the light microscope-temperature-controlled chamber this is reduced to 4 degrees C. The kinetics of microscope-light induced deltaT are described and infrared thermography demonstrates the dissipation of the temperature. Chloroplasts of the cold adapted plant Ranunculus glacialis show the tendency to form stroma-filled protrusions in relation to the exposure temperature. The relative number of chloroplasts with protrusions is reduced at 5 degrees C when compared to 25 degrees C. This effect is reversible. The new light microscope-temperature-controlled chamber will be useful in a wide range of biological applications where a rapid change of temperature during microscopic observations is necessary or has to be avoided allowing a simulation of ecologically relevant temperature scenarios.

Temperature-sensitive formation of chloroplast protrusions and stromules in mesophyll cells of Arabidopsis thaliana

In leaf mesophyll cells of transgenic Arabidopsis thaliana plants expressing GFP in the chloroplast, stromules (stroma-filled tubules) with a length of up to 20 mum and a diameter of about 400-600 nm are observed in cells with spaces between the chloroplasts. They appear extremely dynamic, occasionally branched or polymorphic. In order to investigate the effect of temperature on chloroplasts, we have constructed a special temperature-controlled chamber for usage with a light microscope (LM-TCC). This LM-TCC enables presetting of the temperature for investigation directly at the microscope stage with an accuracy of +/-0.1 degrees C in a temperature range of 0 degrees C to +60 degrees C. With the LM-TCC a temperature-dependent appearance of chloroplast protrusions has been found. These structures have a considerably smaller length-to-diameter ratio than typical stromules and reach a length of 3-5 mum. At 5-15 degrees C (low temperatures), almost no chloroplast protrusions are observed, but they appear with increasing temperatures. At 35-45 degrees C (high temperatures), numerous chloroplast protrusions with a beaklike appearance extend from a single chloroplast. Interaction of stromules with other organelles has also been investigated by transmission electron microscopy. At 20 degrees C, transverse sections of stromules are frequently observed with a diameter of about 450 nm. A close membrane-to-membrane contact of stromules with the nucleus and mitochondria has been visualised. Golgi stacks and microbodies are found in the spatial vicinity of stromules. At 5 degrees C, virtually no chloroplast protrusions or stromules are observed. At 35 degrees C, chloroplast protrusions are present as broader thylakoid-free stroma-filled areas, resulting in an irregular chloroplast appearance.

The effect of ultraviolet radiation on ultrastructure and photosynthesis in the red macroalgae Palmaria palmata and Odonthalia dentata from Arctic waters

In radiation exposure experiments, the effects of mild artificial UV conditions (4.7 W m(-2) UV-A and 0.20 W m(-2) UV-B) plus PAR (25 - 30 micromol photons m(-2) s(-1)) on photosynthesis and ultrastructure of two red algal species from the Arctic have been investigated. While Palmaria palmata was collected from the upper sublittoral of the Kongsfjord (Spitsbergen, Norway), Odonthalia dentata represents a typical deepwater species at this high latitude. After 6 h and 24 h exposure to UV, chlorophyll fluorescence of photosystem II (PS II efficiency, F(v)/F(m)) was determined as an indicator for photosynthetic performance, and the relative electron transport rates in response to increasing photon fluence rates were recorded. In parallel, tissue samples were prepared for the transmission electron microscope (TEM). The presented data clearly demonstrate a significant influence of experimental UV on photosynthetic performance. Photochemical efficiency of PS II of both red algal species decreased to about one third of the initial value under UV. While the PI (photosynthesis-irradiance) curve parameter alpha (positive slope at limiting photon fluence rates) strongly decreased in both plants, the I(k) values (initial value of light-saturated photosynthetic rate) increased 3 - 5-fold. Palmaria palmata does not appear to become photoinhibited under these conditions, but O. dentata showed strong photoinhibition. The TEM results demonstrated that the photosynthetic apparatus was severely influenced by UV in both species, because thylakoid membranes appeared wrinkled, lumen dilatations occurred, and the outer membranes were altered. Moreover, mitochondria were damaged, and numerous plasma vesicles were observed. In conclusion, both red algal species are negatively affected by UV on the physiological and ultrastructural level. However, the differences in photoinhibitory responses correlate well with the vertical depth zonation of P. palmata and O. dentata in the Arctic Kongsfjord.