A Phosphate Transporter Promoter from Arabidopsis thaliana AtPHT1;4 Gene Drives Preferential Gene Expression in Transgenic Maize Roots Under Phosphorus Starvation

Phosphorus (P) stress responsive genes have been identified and characterized, including the high-affinity phosphate transporter AtPHT1;4 from Arabidopsis thaliana. This gene encodes a membrane protein that is primarily expressed in roots under phosphorus deficiency. A 2.3-kb promoter region from AtPHT1;4 has been fused with the β-glucuronidase (GUS) encoding gene and introduced into maize via biolistic bombardment to evaluate its spatiotemporal activity in a heterologous system. AtPHT1;4::GUS expression is detected preferentially in transgenic maize roots under P deficiency. Further analysis of transgenic plants has also revealed that GUS activity is higher in roots than in leaves by about sixfold. These results demonstrate the ability of AtPHT1;4 promoter to direct expression of the reporter gene in a monocot root system under P stress. This property of AtPHT1;4 promoter makes it useful to engineer maize plants to modify the soil’s rhizosphere and increase efficiency of P acquisition under P stress conditions.     

Phytomonas serpens: cysteine peptidase inhibitors interfere with growth, ultrastructure and host adhesion

In this study, we report the ultrastructural and growth alterations caused by cysteine peptidase inhibitors on the plant trypanosomatid Phytomonas serpens. We showed that the cysteine peptidase inhibitors at 10 microM were able to arrest cellular growth as well as promote alterations in the cell morphology, including the parasites becoming short and round. Additionally, iodoacetamide induced ultrastructural alterations, such as disintegration of cytoplasmic organelles, swelling of the nucleus and kinetoplast-mitochondrion complex, which culminated in parasite death. Leupeptin and antipain induced the appearance of microvillar extensions and blebs on the cytoplasmic membrane, resembling a shedding process. A 40 kDa cysteine peptidase was detected in hydrophobic and hydrophilic phases of P. serpens cells after Triton X-114 extraction. Additionally, we have shown through immunoblotting that anti-cruzipain polyclonal antibodies recognised two major polypeptides in P. serpens, including a 40 kDa component. Flow cytometry analysis confirmed that this cruzipain-like protein has a location on the cell surface. Ultrastructural immunocytochemical analysis demonstrated the presence of the cruzipain-like protein on the surface and in small membrane fragments released from leupeptin-treated parasites. Furthermore, the involvement of cysteine peptidases of P. serpens in the interaction with explanted salivary glands of the phytophagous insect Oncopeltus fasciatus was also investigated. When P. serpens cells were pre-treated with either cysteine peptidase inhibitors or anti-cruzipain antibody, a significant reduction of the interaction process was observed. Collectively, these results suggest that cysteine peptidases participate in several biological processes in P. serpens including cell growth and interaction with the invertebrate vector.     

Cell-mediated immunity and the challenges for vaccine development

One of the hallmarks of successful vaccination is the induction of strong and persistent memory T cell responses, a process that involves striking changes in the number and functional properties of T cells. Many questions pertaining to this complex, multifaceted process remain unanswered. Some of the key issues and challenges to optimize memory T cell responses and foster vaccine development include the optimization of effector T cell burst sizes, the use of adjuvants, cytokines and co-stimulatory molecules, epitope enhancement and the standardization of techniques to detect specific T cells. Age also has an impact on vaccine design because of the physiological changes in cell-mediated immunity that occur throughout life.     

A Kinetic Study of the Main Guaco Metabolites Using Syrup Formulation and the Identification of an Alternative Route of Coumarin Metabolism in Humans

For decades guaco species have been empirically used for the treatment of respiratory diseases. However, studies have shown that the toxic and therapeutic effects of the main guaco metabolites are dose-dependent, and none clinical study was done to evaluate the behavior of these substances in humans. In this work, a pilot study measuring the kinetic profile of the main guaco metabolites was performed leading to the knowledge of an alternative route of coumarin metabolism in humans. Initial screenings demonstrated that the administration of 60 mL of guaco syrup (single dose) did not provide sufficient levels of coumarin (COU), 7-hydroxycoumarin (7-HCOU), o-coumaric acid (OCA) and kaurenoic acid (KAU). The pharmacokinetic parameters were calculated by orally administering 60 mL of guaco syrup spiked with 1500 mg of COU. The kinetic study demonstrated that the plasmatic levels of 7-HCOU (considered the main metabolite of COU) were 10 times lower than the levels of COU, and the kinetic profile of 7-HCOU suggests sequential metabolism in the liver with low access of 7-HCOU to the systemic circulation. The study also demonstrated that OCA is one of the main bioavailable metabolites of COU. Therefore, the hydrolysis of the lactone ring forming a carboxylated compound is one of the possible routes of COU metabolism in humans. The half-lives of COU, 7-HCOU and OCA were approximately 4.0, 1.0 and 3.0 h, respectively and there was evidence that the recommended dosage of guaco syrup did not provide sufficient levels of COU, 7-HCOU or OCA to obtain a bronchodilation effect. Clinical studies are necessary to prove the efficacy and safety of products based on guaco.     

Effectiveness of a Randomized School-Based Intervention Involving Families and Teachers to Prevent Excessive Weight Gain among Adolescents in Brazil

Objective

To evaluate the effectiveness of a school-based intervention involving the families and teachers that aimed to promote healthy eating habits in adolescents; the ultimate aim of the intervention was to reduce the increase in body mass index (BMI) of the students.

Design

Paired cluster randomized school-based trial conducted with a sample of fifth graders.

Setting

Twenty classes were randomly assigned into either an intervention group or a control group.

Participants

From a total of 574 eligible students, 559 students participated in the study (intervention: 10 classes with 277 participants; control: 10 classes with 282 participants). The mean age of students was 11 years.

Intervention

Students attended 9 nutritional education sessions during the 2010 academic year. Parents/guardians and teachers received information on the same subjects.

Main Outcome Measurement

Changes in BMI and percentage of body fat.

Results

Intention-to-treat analysis showed that changes in BMI were not significantly different between the 2 groups (β = 0.003; p = 0.75). There was a major reduction in the consumption of sugar-sweetened beverages and cookies in the intervention group; students in this group also consumed more fruits.

Conclusion

Encouraging the adoption of healthy eating habits promoted important changes in the adolescent diet, but this did not lead to a reduction in BMI gain. Strategies based exclusively on the quality of diet may not reduce weight gain among adolescents.

Trial Registration

Clinicaltrials.gov {"type":"clinical-trial","attrs":{"text":"NCT01046474","term_id":"NCT01046474"}}NCT01046474.     

Glucosinolate content and nematicidal activity of Brazilian wild mustard tissues against Meloidogyne incognita in tomato

The wild mustard (Brassica juncea L.), an invasive weed of winter crops in Brazil, was evaluated for glucosinolate content of its plant tissues and nematicidal activity of its dry leaf meal (LM), whole seed meal (WSM) and hexane defatted seed meal (DSM) against Meloidogyne incognita on tomato plants. Sinigrin was the major glucosinolate in LM, WSM and DSM, occurring at concentration of 0.11, 12.2 and 21.9 mg/gdw, respectively. Allyl isothiocyanate (AITC) was the major degradation product and its concentration was highest in DSM followed by WSM and LM. The number of galls, egg masses and eggs on tomato plants was reduced by over 90% by amending soil with 1.6% LM, 0.2% WSM, or 0.05% DSM. Exposure to the volatiles from the amended soils reduced egg eclosion. The soil amendment with LM, WSM and DSM killed the second stage juveniles of M. javanica, M. enterolobii (=M. mayaguensis) and Heterodera glycines. The efficacy of the LM, WSM and DSM for nematode suppression was related to the amount of AITC released in soil.