Is leaf age a predictor for cold tolerance in winter oilseed rape plants?

In the present study, low temperature-dependent physiological changes were investigated through photosynthetic activity and some endogenous mechanisms in two winter oilseed rape cultivars (Brassica napus L. ssp. oleifera cvv. Eurol and Hansen) on the basis of leaf age. Chlorophyll fluorescence measurements demonstrated that low temperature caused decreased photosynthetic activity in both cultivars. However, photosynthetic apparatus in the young leaves of Hansen is more tolerant to low temperature as demonstrated by lower F0 (minimum fluorescence yield) and 1-qp (excitation pressure of photosystem II), higher Fm (maximum fluorescence yield), Fv/Fm and non-photochemical quenching (NPQ) compared with Eurol. In addition, young leaves of Hansen represented marked increase in some antioxidant enzyme activities (superoxide dismutase (SOD), ascorbate peroxidase (APX) and glutathione reductase (GR)) during cold exposure. In the young leaves of Eurol, however, APX and GR activity was decreased by low temperature, indicating lower efficiency of ascorbate-glutathione cycle. Lower antioxidant activity in the young leaves of Eurol may be responsible for increased malondialdehyde (MDA), H2O2 and membrane damage and decreased chlorophyll content as a result of oxidative damage during cold exposure. In the cold-stressed mature leaves, both cultivars represented similar antioxidant capacities and photosynthetic efficiency. As a consequence, coordinated increase in SOD, APX and GR activities, increased capacity to keep quinone A (QA) in an oxidised state (as indicated by lower 1-qp) and accumulation of soluble sugar and proline could be mainly attributed to higher level of tolerance of the young leaves of Hansen to low temperature when compared with Eurol.

Antarctic rocks from continental Antarctica as source of potential human opportunistic fungi.

We assessed the diversity of culturable fungi associated with rocks of continental Antarctica to evaluate their physiological opportunistic virulence potential in vitro. The seventy fungal isolates obtained were identified as nine species of Acremonium, Byssochlamys, Cladosporium, Debaryomyces, Penicillium, and Rhodotorula. Acremonium sp., D. hansenii, P. chrysogenum, P. citrinum, P. tardochrysogenum, and R. mucilaginosa were able to grow at 37 °C; in addition, B. spectabilis displayed a high level of growth at 37 and 45 °C. Thirty-one isolates of P. chrysogenum, P. citrinum, and P. tardochrysogenum were able to produce partial haemolysis on blood agar at 37 °C. Acremonium sp., P. citrinum, and P. tardochrysogenum showed spore sizes ranging from 2.81 to 5.13 µm diameters at 37 °C. Of these, P. chrysogenum and P. tardochrysogenum displayed macro- and micro morphological polymorphism. Our results suggest that rocks of the ultra-extreme cold and dry environment of Antarctica harbour cryptic fungi phylogenetically close to opportunistic pathogenic and mycotoxigenic taxa with physiologic virulence characteristics in vitro.

Culture-dependent and independent techniques to monitor yeast species during cold soak carried out at different temperatures in winemaking.

Transformation of grape must into wine is a process that may vary according to the consumers' requirements. Application of cold soak prior to alcoholic fermentation is a common practice in cellars in order to enhance flavor complexity and extraction of phenolic compounds. However, the effect of this step on wine yeast microbiota is not well-known. The current study simultaneously analyzed the effect of different cold soak temperatures on the microbiological population throughout the process and the use of culture-dependent and independent techniques to study this yeast ecology. The temperatures assayed were those normally applied in wineries: 2.5, 8 and 12°C. PCR-DGGE allowed detection of the most representative species such as Hanseniaspora uvarum, Starmerella bacillaris and Saccharomyces cerevisiae. As could be expected, highest diversity indices were obtained at the beginning of each process, and survival of H. uvarum or S. bacillaris depended on the temperature. Our results are in agreement with those obtained with culture independent methods, but qPCR showed higher precision and a different behavior was observed for each yeast species and at each temperature assayed. Comparison of both culture-independent techniques can provide a general overview of the whole process, although DGGE does not reveal the diversity expected due to the reported problems with the sensitivity of this technique.

Yeast population dynamics during prefermentative cold soak of Cabernet Sauvignon and Malbec wines.

Prefermentative cold soak is a widely used technique in red wine production, but the impact on the development of native yeast species is hardly described. The aim of this work was to analyse the dynamics and diversity of yeast populations during prefermentative cold soak in red wines. Three different temperatures (14 ± 1 °C; 8 ± 1 °C and 2.5 ± 1 °C) were used for prefermentative cold soak in Cabernet Sauvignon and Malbec grape musts. Saccharomyces and non-Saccharomyces populations during cold soak and alcoholic fermentation were analysed. In addition, the impact on chemical and sensory properties of the wines was examined. Yeast dynamics during prefermentative cold soak were temperature dependent. At 14 ± 1 °C, the total yeast population progressively increased throughout the cold soak period. Conversely, at 2.5 ± 1 °C, the yeast populations maintained stable during the same period. Prefermentative cold soak conducted at 14±1°C favoured development of Hanseniospora uvarum and Candida zemplinina, whereas cold soak conducted at 8 ± 1 °C favoured growth of Saccharomyces cerevisiae. At 2.5 ± 1 °C, no changes in yeast species were recorded. Acidity and bitterness, two sensory descriptors, appear to be related to wines produced with prefermentative cold soak carried out at 14 ± 1 °C. This fact could be associated with the increase in non-Saccharomyces during the prefermentation stage. Our results emphasise the importance of the temperature as a determinant factor to allow an increase in non-Saccharomyces population during prefermentative cold soak and consequently to modify sensorial attributes of wines as well as their sensorial impact.

Optimization of cold-adapted lysozyme production from the psychrophilic yeast Debaryomyces hansenii using statistical experimental methods.

UNLABELLED: Statistical experimental designs were employed to optimize culture conditions for cold-adapted lysozyme production of a psychrophilic yeast Debaryomyces hansenii. In the first step of optimization using Plackett-Burman design (PBD), peptone, glucose, temperature, and NaCl were identified as significant variables that affected lysozyme production, the formula was further optimized using a four factor central composite design (CCD) to understand their interaction and to determine their optimal levels. A quadratic model was developed and validated. Compared to the initial level (18.8 U/mL), the maximum lysozyme production (65.8 U/mL) observed was approximately increased by 3.5-fold under the optimized conditions. PRACTICAL APPLICATION: Cold-adapted lysozymes production was first optimized using statistical experimental methods. A 3.5-fold enhancement of microbial lysozyme was gained after optimization. Such an improved production will facilitate the application of microbial lysozyme. Thus, D. hansenii lysozyme may be a good and new resource for the industrial production of cold-adapted lysozymes.

Isolated distal cutaneous thrombosis: an unusual presentation and an interesting etiology.

A middle-aged hypertensive male, with a fatty liver and chronic alcohol intake, relocated to a high altitude of 2100 m above sea level; in the first winter season, he developed bluish skin lesions over the tip of the nose, margins of both ear lobes, both knees, and subungual location. Systemic examination was unremarkable. Skin biopsy showed thrombi in dermal vessels without any evidence of vasculitis; immunofluorescence was negative. Investigations revealed mild elevation in plasma homocysteine levels, weakly positive antinuclear antibodies and elevated antiphospholipid antibodies, methylene tetrahydrofolate reductase C677T heterozygosity, and protein S deficiency. The patient received prednisolone for 2 weeks, aspirin and pentoxyphylline for 3 months, and continues to be on folic acid and vitamin B6. After 3 months, antiphospholipid antibodies and antinuclear antibody levels were normal. Isolated distal cutaneous thrombosis is an uncommon entity and precipitation by extreme cold in a hypertensive male with three thrombophilic states - one transient, one hereditary, and one acquired - is fascinating.

Diversity and evolution of non-Saccharomyces yeast populations during wine fermentation: effect of grape ripeness and cold maceration.

We have evaluated the effect of grape maturity and cold maceration prior to fermentation on the yeast ecology during wine fermentation. Non-Saccharomyces strains were selectively isolated and identified using two rapid PCR techniques, namely enterobacterial repetitve intergenic consensus-PCR and PCR-intron splice sites, in various wine fermentation conditions. These identifications were further complemented and confirmed by restriction fragment length poymorphism and sequencing analysis of the 5.8S-ITS and D1/D2 ribosomal regions, respectively. Eleven species belonging to five genera were identified. Candida stellata, Hanseniaspora uvarum and Hanseniaspora osmophila were the dominant species, representing almost 90% of the isolates. Minor strains presented different species of the genera Candida, Issatchenkia, Zygoascus and Zygosaccharomyces. Selective isolation made it possible to isolate some species that were hardly related to the wine-making process, such as Issatchenkia hanoiensis, a new species that has only been described recently.

Skin and muscle vasomotor reflexes in detecting autonomic dysfunction in leprosy.

There are few tests to assess the function of small unmyelinated nerve fibers. One established test is the skin vasomotor reflex (SVMR), which uses laser doppler flow velocimetry. The SVMR has the disadvantages of being susceptible to interference (from change of temperature and alerting stimuli) and of requiring expensive equipment. An ultrasound doppler method, which is less expensive, can be used to detect muscle vasomotor reflex (MVMR) activity. We sought to compare the efficacy of these two methods in detecting dysfunction of small unmyelinated nerve fibers in patients with leprosy. SVMR was shown to be less sensitive (P < 0.01) and specific (P < 0.001) than MVMR. The favorable results of MVMR may be attributed to its lesser susceptibility to interfering sympathetic vasoconstriction from alerting stimuli. MVMR also reflects larger areas of blood vessel innervation than the laser doppler method. In leprosy, nerve damage is typically patchy and may be missed by the smaller sampling of the laser method.

Effect of temperature on oxygen stores during aerobic diving in the freshwater turtle Mauremys caspica leprosa.

Oxygen stores available for aerobic diving were studied in the freshwater turtle (Mauremys caspica leprosa) at three constant body temperatures (15 degrees, 25 degrees, and 35 degrees C) and during the thermal transient (30 degrees-15 degrees C) induced by immersion in cold water. The term "aerobic dive limit" has been defined as the maximal duration of the dive before lactate increases. This increase occurs when a critical PO2 value is reached, and it is well characterized at lung level by a sharp increase in the lung apnoeic respiratory quotient. Kinetic analysis of lung gas composition during forced dives at fixed body temperature shows that critical PO2 values rise with temperature and that the postventilatory PO2 at the beginning of a dive decreases, so that the two temperature-dependent factors lead to a significant decrease with temperature in the lung O2 stores available for aerobic diving. During dives with transient body cooling, a natural condition in M. caspica leprosa, temperature equilibration occurs fast enough to expand aerobic scope by bearing the critical PO2 to the same value obtained at a fixed temperature of 15 degrees C. These dives are characterized by reversed CO2 transport (from lung to tissues) and therefore by negative values of the lung respiratory quotient; a decrease in temperature increases CO2 capacitance of tissues, resulting in a fall in PCO2 at constant CO2 content. Because this does not occur in the gas phase, PCO2 difference can lead to diffusion in the direction opposite from normal. This pattern may favour lung-to-tissue O2 transfer, through the Bohr effect. Therefore, the aerobic dive limit is reduced at high temperature not only through a metabolic rate effect but also through a marked decrease in the available O2 stores; fast body cooling (30 degrees-15 degrees C) associated with immersion in cold water extends the O2 stores available for aerobic diving to a level similar to that of immersions at constant body temperatures that are in equilibrium with water temperature.

Morphology of cystic structures seen in leprosy biopsy suspensions kept at cooler temperatures.

Cystic structures were seen in good numbers in biopsy suspensions obtained from leprosy patients and kept at cooler temperature. The structures were found arranged in singles, clusters or straight lines. In clusters, small round structures were seen surrounding a large spherical body. The small cystic bodies appeared empty, the medium sized bodies showed fine particles while the large ones showed spherules in and around them. It appears that the seed structure of the cycle emerges from the large spherical bodies.

Filamentous phase in life cycle of M. leprae(?): a preliminary communication.

Certain structures which indicate probable involvement of a filamentous phase in life cycle of M. leprae have been noted in preserved skin biopsy suspensions from lepromatous leprosy cases. These include (i) filaments with empty or pink round spaces within them (ii) conidia-like structures and (iii) membranes with acid fast bacilli. These structures were rare in the fresh material.

Cold reactive lymphocytotoxic antibodies in patients with tuberculoid and lepromatous leprosy.

Fifty-seven sera from leprosy patients and 33 sera from age- and sex-matched hospital controls were tested for the presence of cold-reacting lymphocytotoxic antibodies (LCAs) at 15 degrees C against a panel of 30 HLA-typed normal lymphocytes. Eighteen of 57 (31.6%) leprosy sera and 22 of 33 (67%) control sera showed reactivity, but the strength of reactivity of the patients' sera was significantly more than that of the control group (p less than 0.01 by Wilcoxon rank sum test). Within the leprosy group, there was no significant difference in the reactivity of 30 tuberculoid and 27 lepromatous sera. The occurrence of LCAs was independent of the sex or the HBsAg status of the serum donor. LCA activity was not correlated with treatment status, bacillary load, or reaction state.

Mechanism of phagocytosis of mycobacteria by Schwann cells and their comparison with macrophages.

Factors influencing the phagocytosis of mycobacteria by 33B rat Schwannoma cells and rat peritoneal macrophages were studied. Uptake of 14C-acetate-labeled Mycobacterium w by these cells was used to set up a radiometric phagocytosis assay. Incubation at 4 degrees C and treatment with sodium azide (0.2% to 1%), colchicine (10(-7) to 10(-3) M), cytochalasin B (0.2 micrograms/ml to 25 micrograms/ml), and dibutyryl cyclic AMP (10(-7) to 10(-3) M) inhibited the phagocytosis by both cell types in a similar manner. These experiments demonstrate similarities in the mechanism of phagocytosis of mycobacteria by Schwann cells and macrophages.

A study of autonomic functions in leprosy.

The two groups of leprosy patients were compared with normal for the evaluation of the functional status of the autonomic nervous system, with the aid of several established procedures. Our findings reveal that in the leprosy patients the adrenergic system is hypo-functional as compared to the cholinergic. Further, in maculoanaesthetic group, there appears to be a physiological Dale's vasomoter reversal when adrenaline was used.

A study of autonomic functions in leprosy

The two groups of leprosy patients were compared with normal for the evaluation of the functional status of the autonomic nervous system, with the aid of several established procedures. Our findings reveal that in the leprosy patients the adrenergic system is hypo-functional as compared to the cholinergic. Further, in maculoanaesthetic group, there appears to be a physiological Dale's vasomoter reversal when adrenaline was used.