Biomass accumulation, photochemical efficiency of photosystem II, nutrient contents and nitrate reductase activity in young rosewood plants (Aniba rosaeodora Ducke) submitted to different NO3-:NH4+ ratios

The rosewood (Aniba rosaeodora Ducke) is a native tree species of Amazon rainforest growing naturally in acidic forest soils with reduced redox potential. However, this species can also been found growing in forest gaps containing oxide soils. Variations in the forms of mineral nitrogen (NO3- or NH4+) may be predicted in these different edaphic conditions. Considering that possibility, an experiment was carried out to analyze the effects of different NO3-:NH4+ ratios on the growth performance, mineral composition, chloroplastid pigment contents, photochemical efficiency photosystem II (PSII), and nitrate redutase activity (RN, E.C.1.6.6.1) on A. rosaeodora seedlings. Nine-month-old seedlings were grown in pots with a washed sand capacity of 7.5 kg and submitted to different NO3-:NH4+ ratios (T1 = 0:100%, T2 = 25:75%, T3 = 50:50%, T4 = 75:25%, and T5 = 100:0%). The lowest relative growth rate was observed when the NO3-:NH4+ ratio was equal to 0:100%. In general, high concentrations of NO3- rather than NH4+ favored a greater nutrient accumulation in different parts of the plant. For the chloroplastid pigment, the highest Chl a, Chl b, Chl tot, Chl a/b and Chl tot/Cx+c contents were found in the treatment with 75:25% of NO3-:NH4+, and for Chl b and Cx+c it was observed no difference. In addition, there was a higher photochemical efficiency of PSII (Fv/Fm) when high NO3- concentrations were used. A linear and positive response for the nitrate reductase activity was recorded when the nitrate content increased on the culture substrate. Our results suggest that A. rosaeodora seedlings have a better growth performance when the NO3- concentrations in the culture substrate were higher than the NH4+ concentrations.

Activity of natural killer cells during HIV-1 infection in Brazilian patients

Natural killer cells are increasingly being considered an important component of innate resistance to viruses, but their role in HIV infection is controversial. Some investigators have found that natural killer cells do not confer a protective effect during the progression of HIV disease, whereas others have shown that natural killer cells may be protective and retard the progression of the disease, either through their lytic activity or by a chemokine-related suppression of HIV replication. In this study, we analyzed functional alterations in the activity of natural killer cells during HIV-1 infection using a natural killer cells activity assay with K562 cells as targets. RESULTS: Our results show that the activity of natural killer cells decreases only in the advanced phase of HIV infection and when high (40:1) effector cell-target cell ratios were used. The depression at this stage of the disease may be related to increased levels of some viral factors, such as gp120 or gag, that interfere with the binding capacity of natural killer cells, or to the decreased production of natural killer cells -activity-stimulating cytokines, such as IFN-a and IL-12, by monocytes, a subset of cells that are also affected in the late stage of HIV infection. The data suggest that decreased natural killer cells cell activity may contribute to the severe impairment of the immune system of patients in the late stages of HIV infection.

In vitro antiplasmodial activity and toxicity assessment of plant extracts used in traditional malaria therapy in the Lake Victoria Region

As part of our program screening the flora of the Lake Victoria Region, a total of 54 organic extracts from seven plant families (8 species) were individually tested for antiplasmodial activity against chloroquine-sensitive [Sierra Leone (D-6)] and chloroquine-resistant [Vietnam (W-2)] strains. Only 22% of these extracts exhibited very high in vitro antiplasmodial activity. Six methanol (MeOH) extracts and one chloroform extract showed in vitro antiplasmodial activity against the D-6 Plasmodium falciparum strain, while only three MeOH extracts were active against the W-2 strain. All of the ethyl acetate extracts proved to be inactive against both strains of P. falciparum. A brine shrimp cytotoxicity assay was used to predict the potential toxicity of the extracts. The cytotoxicity to antiplasmodial ratios for the MeOH extracts were found to be greater than 100, which could indicate that the extracts are of low toxicity.

Microbial biomass and activity in litter during the initial development of pure and mixed plantations of Eucalyptus grandis and Acacia mangium

Studies on microbial activity and biomass in forestry plantations often overlook the role of litter, typically focusing instead on soil nutrient contents to explain plant and microorganism development. However, since the litter is a significant source of recycled nutrients that affect nutrient dynamics in the soil, litter composition may be more strongly correlated with forest growth and development than soil nutrient contents. This study aimed to test this hypothesis by examining correlations between soil C, N, and P; litter C, N, P, lignin content, and polyphenol content; and microbial biomass and activity in pure and mixed second-rotation plantations of Eucalyptus grandis and Acacia mangium before and after senescent leaf drop. The numbers of cultivable fungi and bacteria were also estimated. All properties were correlated with litter C, N, P, lignin and polyphenols, and with soil C and N. We found higher microbial activity (CO2 evolution) in litter than in soil. In the E. grandis monoculture before senescent leaf drop, microbial biomass C was 46 % higher in litter than in soil. After leaf drop, this difference decreased to 16 %. In A. mangium plantations, however, microbial biomass C was lower in litter than in soil both before and after leaf drop. Microbial biomass N of litter was approximately 94 % greater than that of the soil in summer and winter in all plantations. The number of cultivable fungi and bacteria increased after leaf drop, especially so in the litter. Fungi were also more abundant in the E. grandis litter. In general, the A. mangium monoculture was associated with higher levels of litter lignin and N, especially after leaf drop. In contrast, the polyphenol and C levels in E. grandis monoculture litter were higher after leaf drop. These properties were negatively correlated with total soil C and N. Litter in the mixed stands had lower C:N and C:P ratios and higher N, P, and C levels in the microbial biomass. This suggests more effective nutrient cycling in mixed plantations in the long term, greater stimulation of microbial activity in litter and soil, and a more sustainable system in general.

Heterofucans from Dictyota menstrualis have anticoagulant activity

Fucan is a term used to denote a family of sulfated L-fucose-rich polysaccharides which are present in the extracellular matrix of brown seaweed and in the egg jelly coat of sea urchins. Plant fucans have several biological activities, including anticoagulant and antithrombotic, related to the structural and chemical composition of polysaccharides. We have extracted sulfated polysaccharides from the brown seaweed Dictyota menstrualis by proteolytic digestion, followed by separation into 5 fractions by sequential acetone precipitation. Gel electrophoresis using 0.05 M 1,3-diaminopropane-acetate buffer, pH 9.0, stained with 0.1% toluidine blue, showed the presence of sulfated polysaccharides in all fractions. The chemical analyses demonstrated that all fractions are composed mainly of fucose, xylose, galactose, uronic acid, and sulfate. The anticoagulant activity of these heterofucans was determined by activated partial thromboplastin time (APTT) using citrate normal human plasma. Only the fucans F1.0v and F1.5v showed anticoagulant activity. To prolong the coagulation time to double the baseline value in the APTT, the required concentration of fucan F1.0v (20 µg/ml) was only 4.88-fold higher than that of the low molecular weight heparin Clexane® (4.1 µg/ml), whereas 80 µg/ml fucan 1.5 was needed to obtain the same effect. For both fucans this effect was abolished by desulfation. These polymers are composed of fucose, xylose, uronic acid, galactose, and sulfate at molar ratios of 1.0:0.8:0.7:0.8:0.4 and 1.0:0.3:0.4:1.5:1.3, respectively. This is the fist report indicating the presence of a heterofucan with higher anticoagulant activity from brown seaweed.

Influence of harvest year in the physicochemical properties and antioxidant activity of flaxseed hull oils from Tunisia

The objective of this research was to determine the effect of five years on physico-chemical characteristics and antioxidant activity of flaxseed hull oils. Oil and protein on flaxseed hull varied between 20.15 and 22.56 and 17.45 and 19.14, respectively. The albumin fraction dominated the seed hull protein composition (44 - 47%). Flaxseed hull oils showed significantly high unsaturated to saturated fatty acid ratios (6.61 - 8.36) and calculated oxidizability (Cox) values (10.88 - 12.30). The physiochemical parameters determined included saponification value (SV) (174 -182 mg KOH/g), unsaponifiable matter (UM) (1.32 - 1.64%), peroxide value (PV) (1.70 - 2.20 mequiv/kg), Oxidation value (OV) (4.40 - 5.90) and oil stability (1.10 - 1.42 h). The highest content of total phenolic acids and total tocopherols were recorded on hull sample collected in 2008. Flavanoid content ranged from 11 to 19 mg/100 g oil. Antioxidant activity differed significantly; the greatest inhibition (61.38%) was for the hull sample collected in 2008.

Exogenous induction of ovarian activity and ovulation and transfer of fresh embryos of domestic cat (Felis catus)

The objective of the present study was the exogenous stimulation of ovarian activity and definition of embryo collection, and transfer protocols, in the domestic cat for potential application in non-domestic endangered species. Sixteen adult queens and two adult male reproducers kept in the experimental cat house at the Morphology sector at the Veterinary Department (DVT), UFV, were used in this study. All the queens received a single application of 150 IU Equine Chorionic Gonadotropin (eCG) in the post estrus to induce ovarian activity and 80 to 84 hours later, received a single application of 100 UI Human Chorionic Gonadotropin (hCG) to induce ovulation. After hCG application, only the donor queens were naturally mated. The receptor queens received extra stimulus for induction of ovulation through manipulation of an intravaginal swab. Five to six days after hCG application, the donor queens were subjected to a laparotomy for embryo collection that was performed by trans-horn uterine washing. On average, six embryos were surgically inovulated. They were classified as type I and III compact morula and blastocysts in four receptor queens. Three animals presented pregnancy confirmed by ultrasound at day 36 and two of these animals gave birth to litters of two and four offsprings, respectively, at 66 and 63 days after induction of ovulation. Except for one still birth, all the offspring developed normally.

Antibacterial activity of Baccharis trimera (Less.) DC. (carqueja) against bacteria of medical interest

Baccharis trimera (Less.) (Asteraceae), popularly know as "carqueja", is a species commonly used in folk medicine for the treatment or prevention of diseases. In this context, the purpose of this work was to study the antibacterial activity of crude hydroalcoholic extract from Baccharis trimera against Gram-positive bacterial strains (Staphylococcus aureus ATCC 29213, Staphylococcus saprophyticus ATCC 15305, Staphylococcus epidermidis ATCC 12228, Enterococcus faecalis ATCC 19433) and Gram-negative bacteria (Escherichia coli EHEC ATCC 43895, Pseudomonas aeruginosa ATCC 27853, Klebsiella pneumoniae ATCC 27736, Salmonella typhi ATCC 19430) of clinical interest. Antibacterial susceptibility was evaluated by broth microdilution assay following the CLSI (formerly the NCCLS) guidelines. The extract from B. trimera showed antibacterial activity against Gram-positive bacteria and the most interesting result was obtained against S. epidermidis that presented Minimal Inhibitory Concentration of 250μg/mL. These results indicate that B. trimera have bacterisostatic potential against Gram-positive bacterial strains of medical interest and could serve as a base for further studies on the use of isolated compounds from this species as future antimicrobials.

Production and photosynthetic activity of Mimosa Verde and Mimosa Roxa lettuce in two farming systems

Lettuce (Lactuca sativa L.) is the most commonly consumed leaf vegetable in the Brazilian diet, and it is a good source of vitamins and minerals. It is widely grown in the conventional farming system. However, the hydroponic farming system has been gaining importance in the market, wining confidence from consumers, who are becoming increasingly more demanding on food quality. The objective of this study was to evaluate the performance of two lettuce cultivars on hydroponic and conventional farming systems for the production of fresh mass (FM) and dry mass (DM), photosynthesis, contents of chlorophyll and anthocyanin. The following two experiments were carried out: hydroponics farming (HF) and conventional farming (CF), performed in protect and unprotect environments, respectively, in Florianópolis, SC. Mimosa Verde cultivar (MV) showed greater fresh mass than Mimosa Roxa (MR), in both farming systems and the two cultivars presented better performance in the hydroponic system (287.7 g MV and 139.1 g MR) than the conventional system (129.7 g MV and 111.8 g MR). Mimosa Verde cultivar presented lower average contents of total chlorophyll (7.7 mg g-¹ FM) than Mimosa Roxa (11.8 mg g-¹FM), and both cultivars displayed higher means for this variable in the hydroponic farming system. Mimosa Roxa presented higher contents of anthocyanin in the conventional system (88.24 mg g-¹ FM) than the ones in the hydroponic system (36.89 mg g-¹ FM). The best results for CO2 net assimilation rate regarded to photosyntheticaly active photon flux density were found in the hydroponic system, for both lettuce cultivars. Variation in the contents of chlorophyll were also found. Those variations were higher in the protected system than in the hydroponic system and contents of anthocyanin were higher in the conventional system.

Biting activity of Aedes scapularis (Rondani) and Haemagogus mosquitoes in Southern Brazil (Diptera: Culicidae)

The biting activity of a population of Aedes scapularis (Rondani), Haemagogus capricornii Lutz and Hg. leucocelaenus (Dyar and Shannon) in Southern Brazil was studied between March 1980 and April 1983. Data were obtained with 25-hour human bait catches in three areas with patchy residual forests, named "Jacaré-Pepira", "Lupo" Farm, and "Sta. Helena" Farm, in the highland region of S. Paulo State (Brazil). Data obtained on Ae. scapularis were compared with those formerly gathered in the "Ribeira'' Valley lowlands, and were similar, except in the "Lupo" Farm study area, where a precrepuscular peak was observed, not recorded at the "Jacaré-Pepira" site or in the "Ribeira" Valley. In all the areas this mosquito showed diurnal and nocturnal activity, but was most active during the evening crepuscular period. These observations support the hypothesis about the successful adaptation of Ae. scapularis to man-made environments and have epidemiological implications that arise from it. As for Haemagogus, results obtained on the "Lupo" and "Sta. Helena" regions agree with previous data obtained in several other regions and show its diurnal activity. The proximity of "Lupo" Farm, where Hg. capricornii and Hg. leucocelaenus showed considerable activity, to "Araraquara" city where Aedes aegypti was recently found, raises some epidemiological considerations about the possibility of urban yellow fever resurgence.

Studies on mosquitoes (Diptera: Culicidae) and anthropic environment: 11 - Biting activity and blood-seeking parity of Anopheles (Kerteszia) in South-Eastern Brazil

An. (Ker.) cruzii and An. (Ker.) bellator were monitored by the use of human bait and Shannon trap collections during a one-year period in 1994. Indoor and outdoor collections were made on human bait and inside the forest environment a Shannon trap was used. Both were undertaken in the evening crepuscular period. Results showed a greater abundance of An. cruzii in the forest, where as An. bellator was more abundant in the domiciliary environment. Through the application of the Polovodova method an age grading was established. Computing the parous and nulliparous females with Christopher's Stage III and above, more than 30.0% of blood-seeking specimens of both anophelines had had a previous blood meal. The higher abundance of An. bellator as compared with that of An. cruzii in the domiciliary environment may be explained by the influence of the neighboring low-lying coastal islands of the estuary system.

Intra-population plasticity of Anopheles darlingi's (Diptera, Culicidae) biting activity patterns in the state of Amapá, Brazil

OBJECTIVE: To assess the variation in Anopheles darlingi's biting activity compared to An. marajoara in the same locality and to biting activity data from other regions. METHODS: Using human bait, eight observations of the biting activity of An. darlingi and An. marajoara were carried out during 1999 and 2000 in the municipality of São Raimundo do Pirativa, state of Amapá, Brazil. Each observation consisted of three consecutive 13-hour collections, close to full moon. There were shifts of collectors in the observation points and nocturnal periods. RESULTS: An. darlingi revealed considerable plasticity of biting activity in contrast to An. marajoara, which showed well-defined crepuscular biting peaks. No significant correlation between density and biting activity was found, but a significant correlation existed between time and proportional crepuscular activity, indicating underlying ecological processes not yet understood. Two of the four available data sets having multiple observations at one locality showed considerable plasticity of this species' biting patterns as well. CONCLUSION: Intra-population variation of biting activity can be as significant as inter-population variation. Some implications in malaria vector control and specific studies are also discussed.

Pesticides and respiratory symptoms among farmers

OBJECTIVE: Despite the intensive use of pesticides in agriculture there are few studies assessing the risk of respiratory conditions from this exposure. The study aimed at quantifying the prevalence of respiratory symptoms among farmers and evaluating its relationship with occupational use of pesticides and the prevalence of respiratory symptoms. METHODS: A cross-sectional study was conducted among 1,379 farmers from two municipalities of Southern Brazil in 1996. Frequency and type of chemical exposure and pesticide poisoning were recorded for both sexes. All subjects aged 15 years or older with at least 15 weekly hours of agricultural activity were interviewed. An adapted questionnaire developed by the American Thoracic Society was used for the assessment of respiratory symptoms. Multivariate logistic regression analysis was carried out. RESULTS: More than half (55%) of interviewees were male. The prevalence of asthma symptoms was 12% and chronic respiratory disease symptoms was 22%. Higher odds ratios for both asthma (OR=1.51; 95% CI: 1.07-2.14) and chronic respiratory disease (OR=1.34; 95% CI 1.00-1.81) symptoms were found in women. Logistic regression analysis identified associations between many forms of exposure to pesticides and increased respiratory symptoms. Occurrence of pesticide poisoning was associated with higher prevalence of asthma symptoms (OR=1.54; 95% CI: 1.04-2.58) and chronic respiratory disease symptoms (OR=1.57; 95% CI: 1.08-2.28). CONCLUSIONS: In spite of causality limitations, the study results provide evidence that farming exposure to pesticides is associated with higher prevalence of respiratory symptoms, especially when the exposure is above two days per month.

Tracking of physical activity from adolescence to adulthood: a population-based study

OBJECTIVE: To assess the association between regular physical activity in adolescence and leisure-time physical activity in adulthood, with emphasis on gender differences. METHODS: A population-based cross-sectional study was carried out in Pelotas, Southern Brazil, in 2003. A representative sample of households was selected in multiple stages and subjects aged 20-59 years were interviewed. Leisure-time physical activity was evaluated using the International Physical Activity Questionnaire. Data on adolescent physical activity were based on subjects' recall. RESULTS: Of 2,577 subjects interviewed, 27.5% were classified as adequately active, and 54.9% reported regular physical activity in adolescence. Subjects who engaged in regular physical activity during adolescence were more likely to be adequately active in adulthood (adjusted prevalence ratio 1.42; 95% CI: 1.23; 1.65). This effect was stronger in women (adjusted prevalence ratio: 1.51; 95% CI: 1.22; 1.86) than men (adjusted prevalence ratio: 1.35; 95% CI: 1.10; 1.67). CONCLUSIONS: Promoting physical activity in school age may be a successful intervention against the epidemic of adult inactivity. Although women were less likely to report regular physical activity in adolescence, the effect of this experience on adult behavior was stronger than in men.