Interactions of Paecilomyces lilacinus strain 251 with the mycorrhizal fungus Glomus intraradices: Implications for Meloidogyne incognita control on tomato

The interactions of Paecilomyces lilacinus strain 251 with the arbuscular mycorrhizal fungus Glomus intraradices and their significance for the control of Meloidogyne incognita on tomato were investigated in greenhouse experiments. Application of P. lilacinus had no effect on the frequency and intensity of tomato root colonization by G. intraradices. Likewise, the decline of the nematophagous fungus densities after single application in soil was not affected by the presence of the mycorrhizal fungus. Single application of P. lilacinus, as pre-planting soil treatment, resulted in significant reduction of nematode damage. In contrast, mycorrhizal inoculation did not provide sufficient biocontrol. Combined application of the two agents did not enhance root protection compared to single treatments. Double treatment of mycorrhized seedlings with P. lilacinus, as seedling drench and pre-planting soil treatment, 4 and 1 week before transplanting, respectively, resulted in the highest reduction of the nematode damage. These results indicate the potential of the commercial P. lilacinus strain 251 and mycorrhiza for integration in nematode control strategies.     

Close association of invading Plasmodium berghei and beta integrin in the Anopheles gambiae midgut

We have used confocal microscopy and an antibody against Anopheles gambiae beta integrin to study this protein's distribution in the mosquito midgut and its relationship to invading Plasmodium berghei parasites. An extensive reorganization of integrin is seen to take place in the midgut epithelial cells following the uptake of either non-infected or parasite-infected blood meal, probably reflecting the reshaping of the gut due to the presence of the food bolus and the peritrophic membrane that surrounds it. Furthermore, malaria parasites are coated with beta integrin immediately upon entry into the epithelium, independent of whether they develop intra- or extracellularly. Although this coat is shed a few days after the invasion, beta integrin remains concentrated in the cells surrounding the maturing oocyst for several days. Finally, the antibody detects a structural change in the midgut epithelial cells in the immediate vicinity of the invading ookinete, which is consistent with Plasmodium-induced apoptosis followed by wound healing. This intimate association suggests a specific role of beta integrin in the invasion process.     

Human Adenovirus Type 2 but Not Adenovirus Type 12 Is Mutagenic at the Hypoxanthine Phosphoribosyltransferase Locus of Cloned Rat Liver Epithelial Cells

Using resistance to the base analog 8-azaguanine as a genetic marker, we showed that adenovirus type 2, but not adenovirus type 12, is mutagenic at the hypoxanthine phosphoribosyltransferase locus of cloned diploid rat liver epithelial cells. Adenovirus type 2 increased the frequency of 8-azaguanine-resistant colonies by up to ninefold over the spontaneous frequency, depending on expression time and virus dose.     

Leptin in immunology

Leptin is an adipokine which conveys information on energy availability. In humans, leptin influences energy homeostasis and regulates neuroendocrine function primarily in states of energy deficiency. As a cytokine, leptin also affects thymic homeostasis and, similar to other proinflammatory cytokines, leptin promotes Th1 cell differentiation and cytokine production. We review herein recent advances on the role of leptin in the pathophysiology of immune responses.     

Variability of Prefrontal Neuronal Discharges before and after Training in a Working Memory Task

Variability of neural discharges can be revealing about the computations and network properties of neuronal populations during the performance of cognitive tasks. We sought to quantify neuronal variability in the prefrontal cortex of naïve monkeys that were only required to fixate, and to examine how this measure was altered by learning and execution of a working memory task. We therefore performed analysis of a large database of recordings in the same animals, using the same stimuli, before and after training. Our results indicate that the Fano Factor, a measure of variability, differs across neurons depending on their functional properties both before and after learning. Fano Factor generally decreased after learning the task. Variability was modulated by task events and displayed lowest values during the stimulus presentation. Nonetheless, the decrease in variability after training was present even prior to the presentation of any stimuli, in the fixation period. The greatest decreases were observed comparing populations of neurons that exhibited elevated firing rate during the trial events. Our results offer insights on how properties of the prefrontal network are affected by performance of a cognitive task.     

Mapping the CRF-urocortins system in human osteoarthritic and rheumatoid synovial fibroblasts: effect of vasoactive intestinal peptide

In addition to the brain and pituitary gland, the corticotrophin‐releasing factor (CRF) system is expressed in peripheral tissues. In this study we characterize the expression of CRF, urocortins (UCN1, UCN2, and UCN3), and their receptors (CRFR1 and CRFR2) in osteoarthritis (OA) and rheumatoid arthritis (RA) fibroblast‐like synoviocytes (FLS). Moreover, we analyze the vasoactive intestinal peptide (VIP) effect on the CRF system, as well as its physiological consequences on mediators of inflammatory/destructive processes. CRF and UCNs exhibit differential pattern in OA and RA‐FLS. By real‐time PCR we detected more expression of CRF and UCN1 in RA, and UCN2 and UCN3 in OA, while the CRFR2 expression was similar. In RA‐FLS VIP treatment resulted in a significant decrease of the proinflammatory peptides, CRF and UCN1, and a significant increase of the potential anti‐inflammatory agents, UCN3 and CRFR2. Using Western blot assays, we showed that the ratio between phospho‐CREB (p‐CREB) and c‐AMP response element‐binding (CREB) is higher in OA and significantly lower in RA‐FLS after VIP treatment, with consequences upon cAMP response element in CRF and UCN1 genes. Real‐time PCR and EIA proved that VIP significantly inhibits cycloxygenase‐2 (COX‐2) and prostaglandin E2 (PGE2) in RA‐FLS. In all cases, we consider significant data when P < 0.05. These data indicate a role of endogenous CRF, UCNs, and CRFR2 in the OA and RA joint microenvironment. We confirm the anti‐inflammatory function of VIP, through the modulation of the expression of CRF system that impacts in a reduction of mediators with inflammatory/destructive functions, supporting its therapeutic potential in rheumatic diseases. J. Cell. Physiol. 226: 3261–3269, 2011. © 2011 Wiley Periodicals, Inc.     

FINE STRUCTURAL STUDIES ON THE INTERPHASE AND DIVIDING APICAL CELLS OF SPHACELARIA TRIBULOIDES (PHAEOPHYTA)1

The apical cells of Sphacelaria tribuloides Menegh. are larger than other thallus cells, contain more organelles and appear polarized. Their tip portion, where they grow, contains a well developed Golgi apparatus, abundant endoplasmic reticulum (ER) membranes, mitochondria, chloroplasts and a large number of small vacuoles. It seems likely that a continuous flow of membranous material from the ER membranes to the dictyosomes and from the latter to the plasmalemma of the extending tip portion takes place. In contrast, the basal pole possesses fewer organelles and is occupied mainly by large-sized, sometimes central vacuoles. The apical cells undergo two distinct types of highly asymmetrical differential divisions giving rise to cells of the thallus and hair initials. During the early stages of mitosis the nuclear envelope remains intact, except for fenestrated poles. Microtubules pass through the fenestrae into the nucleoplasm. During meta-phase, a typical chromosome plate is organized. The sites of attachment of spindle microtubules to the chromosomes are structurally different from the rest of the chromosomes. At late anaphase, the nuclear envelope breaks down completely. During telophase, a new membrane encloses the chromosomes which are decondensed and the nucleoli are reorganized. Cytokinesis proceeds long after mitosis at a stage in which the nuclei have increased in size and have moved farther apart. A membranous furrow develops centripetally, without the participation of microtubules. However, microtubules traverse the thin cytoplasmic strands which, in both interphase and cytokinetic cells, meander among the vacuoles of the basal pole of the cell and the internuclear space. Dictyosomes appear to be involved in the subsequent wall deposition.     

Quaternary structure of a SPATE autotransporter protein

The temperature-sensitive hemagglutinin (Tsh) is a representative of the growing subfamily of secreted bacterial virulence factors, known as serine protease autotransporters of the Enterobacteriaceae (SPATEs). Expressed by avian and human pathogenic strains of Escherichia coli Tsh acts as a serine protease and an adhesin to erythrocytes, hemoglobin, and extracellular matrix proteins. Mature Tsh is comprised of a 106-kDa secreted domain (Tshs) and a 33-kDa outer membrane beta-domain (Tshbeta). Based on the size of beta-domains and functional properties of their passenger domains, all SPATEs are considered to be conventional autotransporters. However, it is unsettled if the conventional autotransporters exist as monomers, oligomers, or multimers (e.g., hexamers). To determine the quaternary structure of Tsh in vitro, we purified Tshbeta from the outer membranes and showed that it is natively folded because it is heat modifiable and resistant to protease digestion. Blue-native polyacrylamide gel electrophoresis of Tshbeta indicated that Tshbeta exists as a monomer or a dimer. The cross-linking analysis demonstrated that purified Tshbeta exists as a monomer. The size-exclusion chromatography and cross-linking analyses of purified Tshs also showed that the passenger domain of Tsh is a monomer. Overall, our data indicated that Tsh is a monomeric protein in vitro and support the concept that the SPATE autotransporters exist as monomers rather than as multimers. Implications of our findings on the mechanism of autotransporter secretion across the outer membrane are discussed.     

Growth and Physiology of Maize (Zea mays L.) in a Nickel-Contaminated Soil and Phytoremediation Efficiency Using EDTA

Journal of Plant Growth Regulation - Nickel (Ni) element is strongly phytotoxic at high concentrations for several plants, but due to its dual behavior and complicated chemistry, it has received...