A Robust Auxin Response Network Controls Embryo and Suspensor Development through a Basic Helix Loop Helix Transcriptional Module.

Land plants reproduce sexually by developing an embryo from a fertilized egg cell. However, embryos can also be formed from other cell types in many plant species. Thus, a key question is how embryo identity in plants is controlled, and how this process is modified during nonzygotic embryogenesis.

A set of domain-specific markers in the Arabidopsis embryo.

We describe a novel set of domain-specific markers that can be used in genetic studies, and we used two examples to show loss of stem cells in a monopteros background. Multicellular organisms can be defined by their ability to establish distinct cell identities, and it is therefore of critical importance to distinguish cell types. One step that leads to cell identity specification is activation of unique sets of transcripts.

Local auxin sources orient the apical-basal axis in Arabidopsis embryos.

Establishment of the embryonic axis foreshadows the main body axis of adults both in plants and in animals, but underlying mechanisms are considered distinct. Plants utilize directional, cell-to-cell transport of the growth hormone auxin to generate an asymmetric auxin response that specifies the embryonic apical-basal axis. The auxin flow directionality depends on the polarized subcellular localization of PIN-FORMED (PIN) auxin transporters.

Imaging of phenotypes, gene expression, and protein localization during embryonic root formation in Arabidopsis.

Plants grow elaborate architectures by repeatedly initiating new organs post-embryonically. The competence to do so depends on the activity of meristems, stem cell niches located at the tips of shoot and root. These meristems are first specified early during embryogenesis.

Different auxin response machineries control distinct cell fates in the early plant embryo.

The cell types of the plant root are first specified early during embryogenesis and are maintained throughout plant life. Auxin plays an essential role in embryonic root initiation, in part through the action of the ARF5/MP transcription factor and its auxin-labile inhibitor IAA12/BDL. MP and BDL function in embryonic cells but promote auxin transport to adjacent extraembryonic suspensor cells, including the quiescent center precursor (hypophysis).

A cellular expression map of the Arabidopsis AUXIN RESPONSE FACTOR gene family.

The plant hormone auxin triggers a wide range of developmental and growth responses throughout a plant's life. Most well-known auxin responses involve changes in gene expression that are mediated by a short pathway involving an auxin-receptor/ubiquitin-ligase, DNA-binding auxin response factor (ARF) transcription factors and their interacting auxin/indole-3-acetic acid (Aux/IAA) transcriptional inhibitors. Auxin promotes the degradation of Aux/IAA proteins through the auxin receptor and hence releases the inhibition of ARF transcription factors.

A versatile set of ligation-independent cloning vectors for functional studies in plants.

With plant molecular biology entering the omics era, there is a need for simple cloning strategies that allow high throughput to systematically study the expression and function of large numbers of genes. Such strategies would facilitate the analysis of gene (sub)families and/or sets of coexpressed genes identified by transcriptomics. Here, we provide a set of 34 ligation-independent cloning (LIC) binary vectors for expression analysis, protein localization studies, and misexpression that will be made freely available.

miR390, Arabidopsis TAS3 tasiRNAs, and their AUXIN RESPONSE FACTOR targets define an autoregulatory network quantitatively regulating lateral root growth.

Plants adapt to different environmental conditions by constantly forming new organs in response to morphogenetic signals. Lateral roots branch from the main root in response to local auxin maxima. How a local auxin maximum translates into a robust pattern of gene activation ensuring the proper growth of the newly formed lateral root is largely unknown.

Auxin enters the matrix--assembly of response machineries for specific outputs.

The basic mechanism of auxin as a modulator of gene expression is now well understood. Interactions among three components are required for this process. Auxin is first perceived by its receptor, which then promotes degradation of inhibitors of auxin response transcription factors.

Liposomes with prolonged blood circulation and selective localization in Klebsiella pneumoniae-infected lung tissue.

Studies of two types of small liposomes, differing with respect to their lipid composition in terms of bilayer fluidity, charge, and hydrophilicity of the liposomal surface, were done to evaluate their usefulness for delivery of encapsulated therapeutic agents to sites of infection. The liposomes showed substantial localization in infected lung tissue after intravenous administration. This was demonstrated in a model of unilateral Klebsiella pneumoniae pneumonia in rats, in which the left lung was infected but the right lung of the same animal developed no infection.

Liposomes as carriers of antimicrobial agents or immunomodulatory agents in the treatment of infections.

Targeting of antimicrobial agents by means of liposomes is under investigation and may be of importance in the treatment of infections that prove refractory to conventional forms of antimicrobial treatment. The ability to achieve a significantly longer residence time of liposomes in plasma and limited uptake of liposomes by the mononuclear phagocyte system opens up new areas of investigation and potential therapeutic application. By manipulating the liposomal composition, rates of uptake and intracellular degradation can be influenced and thereby the rates at which liposome-encapsulated agents are released and become available to exert their therapeutic action.

Enhanced localization of liposomes with prolonged blood circulation time in infected lung tissue.

In an experimental model of unilateral pneumonia caused by Klebsiella pneumoniae in rats we investigated whether intravenous administration of liposomes with prolonged blood circulation time resulted in significant localization of liposomes in infected lung tissue. Liposomes (100 nm) composed of hydrogenated phosphatidylinositol:hydrogenated phosphatidylcholine:cholesterol (molar ratio, 1:10:5) radiolabeled with gallium-67-deferoxamine showed relatively long blood circulation time. The degree of localization of these long circulating liposomes in the infected left lung was significantly higher compared to that of localization of 110 nm egg phosphatidylglycerol:egg phosphatidylcholine:cholesterol (molar ratio, 1:10:5) liposomes which exhibited relatively short blood circulation time.

Liposomes and lipid carriers in the treatment of microbial infections.

Since antibiotic treatment of severe infections is not always successful, intensification of the antibiotic treatment is needed. Targeting of antibiotics to infected tissues or cells by encapsulation in liposomes is under investigation and may be of importance in the treatment of infections that prove refractory to conventional forms of antibiotic therapy. In animal models of intracellular infections involving the mononuclear phagocyte system--parasitic, fungal, bacterial and viral infections--an improved therapeutic index and reduced toxicity resulting from encapsulation of the antibiotics in liposomes have been demonstrated.

Increased efficacy of ganciclovir and foscarnet inhibition of cytomegalovirus replication in vitro by encapsulation in liposomes.

The antiviral effect of ganciclovir and foscarnet encapsulated in liposomes was studied against cytomegalovirus in human embryonic lung fibroblast cells. Substantially greater activity (3.5-fold and 38-fold respectively) in terms of inhibition of virus replication intracellularly was found compared to that seen with non-encapsulated antiviral agents, and liposome encapsulation did not result in increased cytotoxicity.

Antibacterial activity of liposome-entrapped ampicillin in vitro and in vivo in relation to the lipid composition.

The antibacterial activity of liposome-entrapped ampicillin against Listeria monocytogenes was investigated in relation to the lipid composition of the liposomes. This was studied in vitro in mouse peritoneal macrophages infected with L. monocytogenes, as well as in vivo in experimental L.

Effect of free or liposome-encapsulated muramyl dipeptide on uptake and intracellular survival of Listeria monocytogenes in mouse peritoneal macrophages in vitro.

The effect of free versus liposome-encapsulated muramyl dipeptide (MDP) on the uptake and intracellular survival of Listeria monocytogenes in mouse peritoneal macrophages in vitro was investigated. Macrophages in monolayer culture were exposed to free MDP at various concentrations during different time periods before incubation with Listeria monocytogenes. An increase in bacterial uptake dependent on the concentration of MDP and the length of exposure was observed.

Effect of lipid composition on activity of liposome-entrapped ampicillin against intracellular Listeria monocytogenes.

The effect of lipid composition on the intracellular antibacterial activity of ampicillin-containing liposomes was studied in vitro by using mouse peritoneal macrophages infected with Listeria monocytogenes. Two types of liposomes, a fluid type, consisting of cholesterol-phosphatidylcholine-phosphatidylserine (5:4:1), and a solid type, consisting of cholesterol-distearoylphosphatidylcholine-dipalmitoylphosphatidylglyc ero l (10:10:1), were used. Although the cellular uptake of both types of liposomes was similar, they differed with respect to the rate of intracellular degradation.

Liposome-encapsulated ampicillin against Listeria monocytogenes in vivo and in vitro.

In an experimental infection caused by Listeria monocytogenes in mice a considerable enhancement (90-fold) of the therapeutic activity of ampicillin resulting from liposomal encapsulation was observed. The mechanism by which liposomes improved the therapeutic index of ampicillin in this infection appeared to be an increased delivery of the antibiotic to the site of infection, i.e.

Effect of liposome-entrapped ampicillin on survival of Listeria monocytogenes in murine peritoneal macrophages.

The effect of liposomal encapsulation of ampicillin on the antibacterial activity against intracellular Listeria monocytogenes was studied by comparing survival of L. monocytogenes within peritoneal mouse macrophages in the presence of free ampicillin alone or in combination with liposome-entrapped ampicillin. In the presence of 50 micrograms of free ampicillin per ml of the incubation medium, intracellular growth of L.

Free versus liposome-entrapped ampicillin in treatment of infection due to Listeria monocytogenes in normal and athymic (nude) mice.

Efficacy of liposomal as compared with free ampicillin in treatment of infection due to Listeria monocytogenes was studied in normal and congenitally athymic (nude) mice. After intravenous injection the multilamellar vesicles used were taken up mainly by liver and spleen, the target organs of L. monocytogenes.