Low phosphorus (P) availability is one of the most limiting factors for plant productivity in many natural and agricultural ecosystems. Plants display a wide range of adaptive responses to cope with low P stress, which generally serve to enhance P availability in the soil and to increase its uptake by roots. In Arabidopsis (Arabidopsis thaliana), primary root growth inhibition and increased lateral root formation have been reported to occur in response to P limitation. To gain knowledge of the genetic mechanisms that regulate root architectural responses to P availability, we designed a screen for identifying Arabidopsis mutants that fail to arrest primary root growth when grown under low P conditions. Eleven low phosphorus insensitive (lpi) mutants that define at least four different complementation groups involved in primary root growth responses to P availability were identified. The lpi mutants do not show the typical determinate developmental program induced by P stress in the primary root. Other root developmental aspects of the low P rescue system, including increased root hair elongation and anthocyanin accumulation, remained unaltered in lpi mutants. In addition to the insensitivity of primary root growth inhibition, when subjected to P deprivation, lpi mutants show a reduced induction in the expression of several genes involved in the P starvation rescue system (PHOSPHATE TRANSPORTER 1 and 2, PURPLE ACID PHOSPHATASE 1, ACID PHOS-PHATASE 5, and INDUCED BY PHOSPHATE STARVATION 1). Our results provide genetic support for the role of P as an important signal for postembryonic root development and root meristem maintenance and show a crosstalk in developmental and biochemical responses to P deprivation.Phosphorus (P) is one of the most important nutrients for plant growth and development. P plays a myriad of essential biological functions as a structural element in phospholipids and nucleic acids, in energy metabolism, in the regulation of enzymatic activities, and in signal transduction cascades (Raghothama, 1999;Rausch and Bucher, 2002). Although the total content of P in the soil may be high, its bioavailability is generally very low due to mineralization and fixation processes (Hinsinger, 2001). Thus, low P availability is one of the prime limiting factors for plant growth and development in many ecosystems and a major constraint for agricultural productivity in alkaline and acid soils (Ló pez- Bucio et al., 2000).Plants have evolved a wide range of adaptive strategies to adapt to P deficiency and improve P mobilization and uptake from the soil (Raghothama, 1999), including an increase in the synthesis and secretion of organic acids, which enhance the solubilization of P from insoluble inorganic compounds (Jones, 1998); an increase in the production of enzymes such as acid phosphatases and nucleases that release P from soil organic sources (Nü rnberger et al., 1990; Löffler et al., 1992;Duff et al., 1994;Chen et al., 2000); an enhanced expression of highaffinity P transporters to optimize P uptake from ...

Several studies have demonstrated that sera from patients with cancer contain antibodies that recognize a unique group of autologous antigens called tumor-associated antigens (TAA). In the current study, we employed an immunoproteomic approach, combining 2DE, Western blot, and MALDI-MS to identify TAA in the sera of patients diagnosed with infiltrating ductal or in situ carcinoma breast cancer. Sera obtained from 25 newly diagnosed patients with stage II breast cancer and 20 healthy volunteers was evaluated for the presence of novel TAA. Alpha 1-antitrypsin (A1AT) antibodies were detected in 24 of 25 patients with breast cancer (96%) and in 2 of 20 controls (10%). Sensitivity of detection of autoantibodies against A1AT in patients with breast cancer was 96%. Our preliminary results suggest that A1AT and autoantibodies against alpha 1 antitrypsin may be useful serum biomarkers for early-stage breast cancer screening and diagnosis.

Transgenic plants have been employed successfully as a low-cost system for the production of therapeutically valuable proteins, including antibodies, antigens and hormones. Here, we report the expression of a cytokine with immunomodulatory function, mouse interleukin-12 (IL-12), in transgenic tomato plants. Single-chain mouse IL-12 driven by the CaMV 35S promoter, accumulates to high levels in leaves and fruits (up to 7.3 and 3.4 microg per gram of fresh weight, respectively). Mouse IL-12 expressed in tomato displays biological activity in vitro, as determined by interferon-gamma (IFN-gamma) secretion by T cells. Possible uses of this plant-based cytokine involving mucosal delivery are discussed.

The human immunodeficiency virus type 1 (HIV-1) Tat protein is considered a potential candidate vaccine antigen. In an effort to design a strategy for noninvasive vaccination against HIV-1, we developed transgenic tomatoes expressing the Tat protein. Two independent plants testing positive in transgene detection analysis were selected and grown to maturity. Monoclonal antibodies against Tat recognized a protein of the expected size. Interestingly, expression of Tat seemed to be toxic to the plant, as in all cases the fruit exhibited underdeveloped reproductive structures and no seeds. Nine groups of 10 pathogen-free BALB/c male mice were primed either orally, intraperitoneally, or intramuscularly with 10 mg of tomato fruit extract derived from transgenic or wild-type plants and with 10 g of Tat86 recombinant protein. Mice were immunized at days 0, 14, and 28, and given boosters after 15 weeks; sera were drawn 7 days after each booster, and the antibody titer was determined by enzyme-linked immunosorbent assay. All three immunization approaches induced the development of a strong anti-Tat immunological response, which increased over time. Isotype subclass determination showed the presence of mucosal (immunoglobulin A) immunity soon after the beginning of the oral immunization protocol, and the data were confirmed by the presence of anti-Tat antibodies in fecal pellets and in vaginal washes. We also demonstrated that sera from immunized mice inhibited with high efficiency recombinant Tat-dependent transactivation of the HIV-1 long terminal repeat promoter. This neutralization activity might be relevant for the suppression of extracellular Tat activities, which play an important role in HIV disease development.

Cell-surface viral proteins most frequently enter the cell through clathrin or caveolae endocytosis. Respiratory syncytial virus antigen internalization by immune cells is via caveolin, however, uptake of paramyxovirus cell membrane proteins by non-immune cells is done through clathrin-coated pits. In this work, the uptake of respiratory syncytial virus cell surface glycoproteins by non-immune human epithelial cells was investigated through indirect immunofluorescence with polyclonal anti-RSV antibody and confocal lasser-scanner microscopy. Clathrin and caveolae internalization pathways were monitored through specific inhibitors monodansylcadaverine (MDC) and methyl-beta-cyclodextrin (MBCD), respectively. Internalization of RSV antigens was inhibited by MDC but not by MBCD, implying that clathrin-mediated endocytosis is the major uptake route of RSV antigens by an epithelial human cell line.

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SummaryHost control of mycobacterial infection, in both human and mouse models, has been shown to be associated with the production of interferon (

Rhipicephalus (Boophilus) microplus is an obligate haematophagous arthropod and the major problem for cattle industry due to economic losses it causes. The parasite shows a remarkable adaptability to changing environmental conditions as well as an exceptional ability to survive long-term starvation. This ability has been related to a process of intracellular protein degradation called autophagy. This process in ticks is still poorly understood and only few autophagy-related (ATG) genes have been characterized. The aim of the present study was to examine the ESTs database, BmiGI, of R. microplus searching for ATG homologues. We predicted five putative ATG genes, ATG3, ATG4, ATG6 and two ATG8s. Further characterization led to the identification of RmATG8a and RmATG8b, homologues of GABARAP and MAP1LC3, respectively, and both of them belonging to the ATG8 family. PCR analyses showed that the expression level of RmATG8a and RmATG8b was higher in egg and larval stages when compared to ovary and midgut from adult ticks. This up-regulation coincides with the period in which ticks are in a starvation state, suggesting that autophagy is active in R. microplus.