Effect of water table drawdown on peatland nutrient dynamics: implications for climate change

It is anticipated that a lowering of the water table and reduced soil moisture levels in peatlands may increase peat decomposition rates and consequently affect nutrient availability. However, it is not clear if patterns will be consistent across different peatland types or within peatlands given the natural range of ecohydrological conditions within these systems. We examined the effect of persistent drought on peatland nutrient dynamics by quantifying the effects of an experimentally lowered water table position (drained for a 10-year period) on peat KCl-extractable total inorganic nitrogen (ext-TIN), peat KCl-extractable nitrate (ext-NO₃ ^?), and water-extractable ortho-phosphorus (ext-PO₄ ^3?) concentrations and net phosphorus (P) and nitrogen (N) mineralization and nitrification rates at natural (control) and drained microforms (hummocks, lawns) of a bog and poor fen near Québec City, Canada. Drainage (water table drawdown) decreased net nitrification rates across the landscape and increased ext-NO₃ ^? concentrations, but did not affect net N and P mineralization rates or ext-TIN and ext-PO₄ ^3? concentrations. We suggest that the thick capillary fringe at the drained peatland likely maintained sufficient moisture above the water table to limit the effects of drainage on microbial activity, and a 20 cm lowering of the water table does not appear to have been sufficient to create a clear difference in nutrient dynamics in this peatland landscape. We found some evidence of differences in nutrient concentrations with microforms, where concentrations were greater in lawn than hummock microforms at control sites indicating some translocation of nutrients. In general, the same microtopographic differences were not observed at drained sites. The general spatial patterns in nutrient concentrations did not reflect net mineralization/immobilization rates measured at our control or drained peatlands. Rather, the spatial patterns in nutrient availability may be regulated by differences in vegetation (mainly Sphagnum moss) cover between control and drained sites and possibly differences in hydrologic connection between microforms. Our results suggest that microform distribution and composition within a peatland may be important for determining how peatland nutrient dynamics will respond to water table drawdown in northern peatlands, as some evidence of microtopographic differences in nutrient dynamics was found.     

QSAR modeling and transmission electron microscopy stereology of altered mitochondrial ultrastructure of white blood cells in patients diagnosed as schizophrenic and treated with antipsychotic drugs.

Treatment of patients diagnosed as schizophrenic with antipsychotic drugs (neuroleptics) is known to cause occasional unexplained depletion of white blood cells, especially neutrophil granulocytes. It has been known for many years that neuroleptics can interfere with the mitochondrial respiratory chain in vitro. Because there has been a growing interest recently in mitochondrial targeting of drugs, and since a quantitative structure-activity relationship (QSAR) model that predicts mitochondrial accumulation of neuroleptics has been published, we investigated the effects of neuroleptics on white blood cell mitochondria. Venous blood samples were collected from both patients undergoing treatment with neuroleptics and healthy volunteers. The samples were processed for transmission electron microscopy. The resulting images of white blood cells were analyzed using stereology to compare quantitatively mitochondrial morphology in the patient and control groups. We found that in patients, but not in controls, there was swelling of mitochondria and fragmentation of the mitochondrial cristae. There also were fewer mitochondria in patients than in controls, although due to the swelling of the organelles, the volume density of mitochondria in the two groups was not significantly different. Such changes are typical of a toxic insult. Consequently, it seems plausible that, since schizophrenia is not a disease considered to affect white blood cells per se, these changes probably are due to the medication.     

QSAR modeling and transmission electron microscopy stereology of altered mitochondrial ultrastructure of white blood cells in patients diagnosed as schizophrenic and treated with antipsychotic drugs.

Treatment of patients diagnosed as schizophrenic with antipsychotic drugs (neuroleptics) is known to cause occasional unexplained depletion of white blood cells, especially neutrophil granulocytes. It has been known for many years that neuroleptics can interfere with the mitochondrial respiratory chain in vitro. Because there has been a growing interest recently in mitochondrial targeting of drugs, and since a quantitative structure-activity relationship (QSAR) model that predicts mitochondrial accumulation of neuroleptics has been published, we investigated the effects of neuroleptics on white blood cell mitochondria. Venous blood samples were collected from both patients undergoing treatment with neuroleptics and healthy volunteers. The samples were processed for transmission electron microscopy. The resulting images of white blood cells were analyzed using stereology to compare quantitatively mitochondrial morphology in the patient and control groups. We found that in patients, but not in controls, there was swelling of mitochondria and fragmentation of the mitochondrial cristae. There also were fewer mitochondria in patients than in controls, although due to the swelling of the organelles, the volume density of mitochondria in the two groups was not significantly different. Such changes are typical of a toxic insult. Consequently, it seems plausible that, since schizophrenia is not a disease considered to affect white blood cells per se, these changes probably are due to the medication.     

Brief Mindfulness Meditation Improves Mental State Attribution and Empathizing

The ability to infer and understand the mental states of others (i.e., Theory of Mind) is a cornerstone of human interaction. While considerable efforts have focused on explicating when, why and for whom this fundamental psychological ability can go awry, considerably less is known about factors that may enhance theory of mind. Accordingly, the current study explored the possibility that mindfulness-based meditation may improve people’s mindreading skills. Following a 5-minute mindfulness induction, participants with no prior meditation experience completed tests that assessed mindreading and empathic understanding. The results revealed that brief mindfulness meditation enhanced both mental state attribution and empathic concern, compared to participants in the control group. These findings suggest that mindfulness may be a powerful technique for facilitating core aspects of social-cognitive functioning.     

Integrin-alphavbeta6, a putative receptor for foot-and-mouth disease virus, is constitutively expressed in ruminant airways.

Evolved functions of integrin-alpha(v)beta(6) include roles in epithelial cell-extracellular matrix protein interactions and in the binding and activation of latent TGF-beta(1). Integrin-alpha(v)beta(6) is also exploited as a receptor by foot-and-mouth disease virus (FMDV) and may play a significant role in its transmission and pathogenesis. The ovine beta(6) integrin subunit was cloned and sequenced (EMBL accession no. AJ439062). Screening of normal ovine tissues by RT-PCR and immunocytochemistry confirmed that integrin-alphavbeta6 is restricted to sheep epithelial cells. Integrin-alphavbeta6 expression was detected in epithelia of the airways, oral cavity, gastrointestinal tract, kidney, sweat glands, hair follicle sheaths, and the epidermis of pedal coronary band (PB) but not of normal skin. Consistent with FMDV tropism, integrin-alphavbeta6 was detected within the basal layers of the stratified squamous epithelium of the oral mucosa and PB. In addition, integrin-alphavbeta6 appears to be constitutively expressed in the normal airways of both cattle and sheep. The latter finding suggests that ruminant airway epithelium presents a highly accessible target for initiation of infection with FMDV by inhalation.