Regulation of the adaptation to zinc deficiency in plants

The molecular mechanisms by which plants sense their micronutrient status, and adapt to their environment in order to ensure a sufficient micronutrient supply, are poorly understood. Zinc is an essential micronutrient for all living organisms. when facing a shortage in zinc supply, plants adapt by enhancing the zinc uptake capacity. The molecular regulators controlling this adaptation were recently identified. in this mini-review, we highlight recent progress in understanding the adaptation to zinc deficiency in plants and discuss the future challenges to fully unravel its molecular basis.Key words: adaptation, zinc deficiency, biofortification, molecular regulators, plant nutritionIn an increasingly populated world, agricultural production is an essential element of social development. Agriculture is the primary source of all nutrients required for human life, and nutrient sufficiency is the basis for good health and welfare of the human population.¹ Soils with zinc deficiency are widespread in the world, affecting large areas of cultivated soils in India, Turkey, China, Brazil and Australia,^2,3 making zinc the most common crop micronutrient deficiency.⁴ In addition, risk of inadequate zinc diet and zinc malnutrition are estimated to affect one-third of the global human population, i.e., around two billion people.⁵ Most affected are people living in developing countries, where diets are rich in cereal-based foods. Cereal grains are rich in phytate, which is a potent anti-nutrient, limiting micronutrient bioavailability.⁶ Zinc deficiency in crop production can be easily ameliorated through zinc fertilization, making agronomic biofortification an important strategy,³ however in the poorer regions, the required infrastructure to provide a reliable supply of zinc fertilizers of sufficient quality, is often not available. In those situations, biofortified crops, in which the zinc status of crops is genetically improved by selective breeding or via biotechnology, offer a rural-based intervention that will more likely reach the population.⁷ Different traits can be targeted to developing such improved crops, such as plant zinc deficiency tolerance, zinc use efficiency and the accumulation of zinc in edible parts. However, insufficient knowledge on the molecular mechanisms and the regulation of the zinc homeostasis network in plants is a serious bottleneck when pursuing zinc biofortification.     

A first insight into the genetic diversity of Mycobacterium tuberculosis in Dar es Salaam, Tanzania, assessed by spoligotyping

Background  

Tanzania has a high tuberculosis incidence, and genotyping studies of Mycobacterium tuberculosis in the country are necessary in order to improve our understanding of the epidemic. Spoligotyping is a potentially powerful genotyping method due to fast generation of genotyping results, high reproducibility and low operation costs. The recently constructed SpolDB4 database and the model-based program 'spotclust' can be used to assign isolates to families, subfamilies and variants. The results of a study can thus be analyzed in a global context.     

Is disturbed clearance of apoptotic keratinocytes responsible for UVB-induced inflammatory skin lesions in systemic lupus erythematosus?

Apoptotic cells are thought to play an essential role in the pathogenesis of systemic lupus erythematosus (SLE). We hypothesise that delayed or altered clearance of apoptotic cells after UV irradiation will lead to inflammation in the skin of SLE patients. Fifteen SLE patients and 13 controls were irradiated with two minimal erythemal doses (MEDs) of ultraviolet B light (UVB). Subsequently, skin biopsies were analysed (immuno)histologically, over 10 days, for numbers of apoptotic cells, T cells, macrophages, and deposition of immunoglobulin and complement. Additionally, to compare results with cutaneous lesions of SLE patients, 20 biopsies of lupus erythematosus (LE) skin lesions were analysed morphologically for apoptotic cells and infiltrate. Clearance rate of apoptotic cells after irradiation did not differ between patients and controls. Influx of macrophages in dermal and epidermal layers was significantly increased in patients compared with controls. Five out of 15 patients developed a dermal infiltrate that was associated with increased epidermal influx of T cells and macrophages but not with numbers of apoptotic cells or epidermal deposition of immunoglobulins. Macrophages were ingesting multiple apoptotic bodies. Inflammatory lesions in these patients were localised near accumulations of apoptotic keratinocytes similar as was seen in the majority of LE skin lesions. In vivo clearance rate of apoptotic cells is comparable between SLE patients and controls. However, the presence of inflammatory lesions in the vicinity of apoptotic cells, as observed both in UVB-induced and in LE skin lesions in SLE patients, suggests that these lesions result from an inflammatory clearance of apoptotic cells.     

Inhibition of protein geranylgeranylation induces apoptosis in synovial fibroblasts

Statins, competitive inhibitors of hydroxymethylglutaryl-CoA reductase, have recently been shown to have a therapeutic effect in rheumatoid arthritis (RA). In RA, synovial fibroblasts in the synovial lining, are believed to be particularly important in the pathogenesis of disease because they recruit leukocytes into the synovium and secrete angiogenesis-promoting molecules and proteases that degrade extracellular matrix. In this study, we show a marked reduction in RA synovial fibroblast survival through the induction of apoptosis when the cells were cultured with statins. Simvastatin was more effective in RA synovial fibroblasts than atorvastatin, and both statins were more potent on tumor necrosis factor-α-induced cells. In contrast, in osteoarthritis synovial fibroblasts, neither the statin nor the activation state of the cell contributed to the efficacy of apoptosis induction. Viability of statin-treated cells could be rescued by geranylgeraniol but not by farnesol, suggesting a requirement for a geranylgeranylated protein for synovial fibroblast survival. Phase partitioning experiments confirmed that in the presence of statin, geranylgeranylated proteins are redistributed to the cytoplasm. siRNA experiments demonstrated a role for Rac1 in synovial fibroblast survival. Western blotting showed that the activated phosphorylated form of Akt, a protein previously implicated in RA synovial fibroblast survival, was decreased by about 75%. The results presented in this study lend further support to the importance of elevated pAkt levels to RA synovial fibroblast survival and suggest that statins might have a beneficial role in reducing the aberrant pAkt levels in patients with RA. The results may also partly explain the therapeutic effect of atorvastatin in patients with RA.     

Biomonitoring of primary aluminium industry workers: detection of micronuclei and repairable DNA lesions by alkaline SCGE

The genetic effects of occupational exposure to low polycyclic aromatic hydrocarbon (PAH) concentrations were investigated in primary aluminium industry workers. The study subjects were employed in a plant that uses pre-baked anode cells, and has relatively low PAH contamination. Forty-two male workers belonging to different job categories (anode fabrication, baking, rodding, electrolysis, maintenance), together with 16 male local residents with no occupational exposure to PAHs were selected for the analysis of micronuclei and DNA lesions in peripheral lymphocytes. The incidence of micronuclei determined in 1000 cytokinesis-blocked cells in each subject was not significantly different between workers and controls (8.5+/-5.4 per thousand versus 9.7+/-4.9 per thousand, respectively), nor between smokers and non-smokers (8.3+/-5.8 per thousand versus 9.2+/-5.1 per thousand), but was significantly (P<0.05) related to the subjects' age. Also the analysis of DNA damage in unstimulated and mitogen-stimulated lymphocytes by single cell gel electrophoresis (SCGE) did not show significant differences between the studied groups (average tail moment values were 0.53+/-0.53 and 0.49+/-0.45 microm in exposed subjects and controls, respectively). However, when lymphocytes were cultured in the presence of cytosine arabinoside (Ara-C, 1 microg/ml for 16h) the SCGE analysis revealed a significant (P=0.018) difference in tail moment values between aluminium workers and controls (1.73+/-1.05 microm versus 0.93+/-0.88 microm, respectively). This difference may highlight an excess of relatively stable DNA lesions, that do not affect strand integrity, and are expressed as intermediates of excision repair in stimulated cells, when gap refilling is inhibited by cytosine arabinoside (Ara-C).     

Dissociation between rate of hepatic lipoprotein secretion and hepatocyte microtubule content

The fact that colchicines inhibits hepatic secretion of very low density lipoprotein (VLDL) particles has been interpreted to mean that microtubules are involved in hepatic VLDL secretion. To further define this relationship, we have attempted to see if changes in hepatic VLDL secretion are associated with changes in hepatocyte microtubule or tubulin content. Accordingly, hepatic secretion of VLDL was increased in rats, and the hepatocyte content of both microtubules (using quantitative morphometric methods) and tubulin (using a time-decay colchicine binding assay) was determined. In acute experiments, VLDL secretion was increased by perfusion of isolated rat livers for 2 h with varying concentrations of free fatty acids (FFA). Results indicate that hepatic VLDL triglyceride (TG) secretion at perfusate FFA levels of 0.7 μEq/ml is threefold greater (P < 0.01) than when livers are perfused without added FFA. However, no differences are observed in the content of microtubules in these livers: specifically, microtubules occupy 0.029 percent of hepatocyte cytoplasm in livers perfused without FFA and 0.030 percent of cytoplasm in livers perfused with FFA. In chronic experiments, rats were fed for 1 wk with either standard rat chow or a hyperlipidemic (sucrose/lard) diet. With the experimental diet, plasma triglyceride levels increase threefold over controls, and liver VLDL-TG production, as determined by [(3)H]glycerol turnover studies, is 55 percent greater (P < 0.01) than controls. However, microtubules occupy 0.027 percent of the cytoplasm of hepatocyte cytoplasm whether rats are on standard or hyperlipidemic diets. Furthermore, the tubulin content of isolated hepatocytes does change, and represents 1 percent of hepatocyte soluble protein, irrespective of diet. These results suggest that increases in hepatic VLDL secretion can occur without any demonstrable change in hepatocyte assembled microtubule or tubulin content, and raise questions as to the role played by microtubules in hepatic VLDL secretion.     

Otomycosis — a clinico-mycological study and efficacy of mercurochrome in its treatment

A total of 110 patients of symptomatic otomycosis was investigated, prospectively. Aural swabs were collected on 1st, 7th and 14th day and examined by direct microscopy and culture for fungi. Of these, 80 patients found to be having pure fungal infection, were taken up for mycological and therapeutic study. Fungi belonging to genus Aspergillus were isolated in 76 (95.0%) patients of which Aspergillus niger was the commonest isolate in 46 (57.5%), followed by A. flavus in 27 (33.7%), A. fumigatus in 3 (3.7%), Candida species in 3 (3.7%) and Mucor in 1 (1.2%). The patients were of all age groups but majority were between 21 and 30 years and the male-female ratio was equal. Of the total of 40 male patients, twenty-one were Sikhs using turban. Before developing the symptoms, forty five patients used oil, mixture of oil and garlic juice, antibiotics, steroids, antiseptics or wax solvent as ear drops. Only two patients were diabetic! No patient had fungal infection elsewhere in the body. The patients were called for regular follow-up for three weeks. In forty cases mercurochrome was applied as the antifungal agent after cleaning the external auditory canal, in twenty-three clotrimazole and in rest of the seventeen patients miconazole was used. On 7th day, only 11 (13.7%) patients grew different fungi in culture. They became symptom-free on 14th day and no fungal material could be seen on otoscopy, direct microscopy or culture. Mercurochrome was found to be most effective in these patients.     

Daily physical activity in ankylosing spondylitis: validity and reliability of the IPAQ and SQUASH and the relation with clinical assessments

Introduction

The aim of this study was to investigate the construct validity and test-retest reliability of the International Physical Activity Questionnaire (IPAQ; long form) and the Short QUestionnaire to Assess Health-enhancing physical activity (SQUASH) and to investigate the relation between daily physical activity and clinical assessments in patients with ankylosing spondylitis (AS).

Methods

For validity, the self-report questionnaires IPAQ and SQUASH were compared with daily physical activity assessed with the ActiGraph accelerometer during 7 consecutive days in 63 AS outpatients. For reliability, the IPAQ and SQUASH were administered twice approximately 1 week apart in 52 AS outpatients. In all 115 patients, clinical assessments were performed at the outpatient clinic.

Results

IPAQ and SQUASH total scores correlated significantly with accelerometer outcome: ρ = 0.38 and r = 0.35, respectively. Intraclass correlation coefficients between first and second assessments of the IPAQ and SQUASH were 0.83 and 0.89, respectively. Bland-Altman analyses showed no systemic bias, but in particular for the IPAQ the 95% limits of agreement were wide. Daily physical activity assessed by accelerometer, IPAQ, and SQUASH correlated significantly with disease activity, physical activity, and quality of life. A relation with spinal mobility was found only for the accelerometer and SQUASH. The direction of these correlations indicates that higher daily physical activity is related to lower disease activity and better physical function, spinal mobility and quality of life.

Conclusions

Both physical activity questionnaires showed modest construct validity. The SQUASH showed good test-retest reliability, superior to the IPAQ. These results indicate that the SQUASH is more suitable than the IPAQ to assess daily physical activity in AS population studies. However, it is desirable to add questions on AS-specific physical activity. Further studies are needed to investigate the causality of the relation between daily physical activity and clinical assessments.     

Evaluation of APOE polymorphisms and the risk for age-related macular degeneration in a Southeastern Brazilian population

This study aimed to evaluate the role of APOE polymorphisms (rs429358 and rs7412) in the risk of age-related macular degeneration in a sample of the Southeastern Brazilian population. Seven hundred and five unrelated individuals were analyzed, 334 with age-related macular degeneration (case group), and 371 without the disease (control group). In the case group, patients were further stratified according to disease phenotypes, divided into dry and wet age-related macular degeneration, and non-advanced and advanced age-related macular degeneration. APOE polymorphisms (rs429358 and rs7412) were evaluated through polymerase chain reaction and direct sequencing. In the comparison of cases vs. controls, none of the associations reached statistical significance, considering the Bonferroni-adjusted P-value, although there was a suggestive protection for the E3/E4 genotype (OR = 0.626; P-value = 0.037) and E4 carriers (OR = 0.6515; P-value = 0.047). Statistically significant protection for both the E3/E4 genotype and E4 carriers was observed in the comparisons: advanced age-related macular degeneration vs. controls (OR = 0.3665, P-value = 0.491 × 10⁻³ and OR = 0.4031, P-value = 0.814 × 10⁻³, respectively), advanced age-related macular degeneration vs. non-advanced age-related macular degeneration (OR = 0.2529, P-value = 0.659 × 10⁻⁴ and OR = 0.2692, P-value = 0.631 × 10⁻⁴, respectively). In the comparison of wet age-related macular degeneration vs. control, protection was statistically significant only for E3/E4 (OR = 0.4052, P-value = 0.001). None of the comparisons demonstrated any significant association for E2 genotypes or E2 carriers in age-related macular degeneration risk in this study. Findings suggest a protective role of the E4 haplotype in the APOE gene in the risk for advanced and wet forms of age-related macular degeneration, in a sample of the Brazilian population. To our knowledge, this is the first Brazilian study to show the association between APOE polymorphisms and age-related macular degeneration.     

Living with myotonic dystrophy; what can be learned from couples? a qualitative study

Background  

Myotonic dystrophy type 1 (MD1) is one of the most prevalent neuromuscular diseases, yet very little is known about how MD1 affects the lives of couples and how they themselves manage individually and together. To better match health care to their problems, concerns and needs, it is important to understand their perspective of living with this hereditary, systemic disease.