Irrigation and its effect on polyphagous shot hole borer attack

Polyphagous shot hole borer (PSHB), Euwallacea whitfordiodendrus (Schedl) (Coleoptera: Curculionidae, Scolytinae), is an ambrosia beetle that has recently invaded southern California, USA. This beetle successfully attacks and reproduces in a multitude of tree species. As direct control methods are limited, we investigated cultural management options, and sought to determine whether irrigation affects the number of attacks host trees experienced. If irrigation plays a role, cultural control methods could be recommended to managers and growers. Three separate experiments were conducted that monitored the number of attacks on trees with different levels of irrigation. Two experiments examined PSHB attacks in established landscape trees where irrigation was either present or absent. A third experiment used young potted box elder with irrigation controlled with timed emitters. In all three experiments, the level of irrigation received by the trees did not affect the number of attacks. The results suggest that changes in irrigation practices do not affect risk from PSHB attack.     

Common and specific responses to iron and phosphorus deficiencies in roots of apple tree (Malus × domestica)

Plant Molecular Biology - Iron and phosphorus are abundant elements in soils but poorly available for plant nutrition. The availability of these two nutrients represents a major constraint for...     

Methylglyoxal accumulation de-regulates HoxA5 expression,thereby impairing angiogenesis in glyoxalase 1 knock-down mouse aortic endothelial cells

Impaired angiogenesis leads to long-term complications and is a major contributor of the high morbidity in patients with Diabetes Mellitus (DM). Methylglyoxal (MGO) is a glycolysis byproduct that accumulates in DM and is detoxified by the Glyoxalase 1 (Glo1). Several studies suggest that MGO contributes to vascular complications through mechanisms that remain to be elucidated. In this study we have clarified for the first time the molecular mechanism involved in the impairment of angiogenesis induced by MGO accumulation.Angiogenesis was evaluated in mouse aortic endothelial cells isolated from Glo1-knockdown mice (Glo1KD MAECs) and their wild-type littermates (WT MAECs). Reduction in Glo1 expression led to an accumulation of MGO and MGO-modified proteins and impaired angiogenesis of Glo1KD MAECs. Both mRNA and protein levels of the anti-angiogenic HoxA5 gene were increased in Glo1KD MAECs and its silencing improved both their migration and invasion. Nuclear NF-?B-p65 was increased 2.5-fold in the Glo1KD as compared to WT MAECs. Interestingly, NF-?B-p65 binding to HoxA5 promoter was also 2-fold higher in Glo1KD MAECs and positively regulated HoxA5 expression in MAECs. Consistent with these data, both the exposure to a chemical inhibitor of Glo1 “SpBrBzGSHCp2” (GI) and to exogenous MGO led to the impairment of migration and the increase of HoxA5 mRNA and NF-?B-p65 protein levels in microvascular mouse coronary endothelial cells (MCECs).This study demonstrates, for the first time, that MGO accumulation increases the antiangiogenic factor HoxA5 via NF-?B-p65, thereby impairing the angiogenic ability of endothelial cells.     

Understanding the Hydraulics of Porous Pipes: Tradeoffs Between Water Uptake and Root Length Utilization

The water uptake region in roots is several hundred times longer than the root diameter. The distributed nature of the uptake zone requires that the hydraulic design of roots be understood by analogy to flow through a porous pipe. Here we present results of an analytical and experimental investigation that allowed an in-depth analysis of root hydraulic properties. Measurements on nodal maize roots confirm the nonlinear distribution of water uptake predicted by the porous pipe model. The major design parameter governing the distribution of water uptake along a porous pipe is the ratio between its axial and radial hydraulic resistance. However, total flow is proportional to the pipe's overall resistance. These results suggest the existence of a tradeoff between the effective utilization of root length and the total capacity for water uptake.     

Legionella pneumophila CsrA is a pivotal repressor of transmission traits and activator of replication

Legionella pneumophila can replicate inside amoebae and also alveolar macrophages to cause Legionnaires' Disease in susceptible hosts. When nutrients become limiting, a stringent-like response coordinates the differentiation of L. pneumophila to a transmissive form, a process mediated by the two-component system LetA/S and the sigma factors RpoS and FliA. Here we demonstrate that the broadly conserved RNA binding protein CsrA is a global repressor of L. pneumophila transmission phenotypes and an essential activator of intracellular replication. By analysing csrA expression and the phenotypes of csrA single and double mutants and a strain that expresses csrA constitutively, we demonstrate that, during replication in broth, CsrA represses every post-exponential phase phenotype examined, including cell shape shortening, motility, pigmentation, stress resistance, sodium sensitivity, cytotoxicity and efficient macrophage infection. At the transition to the post-exponential phase, LetA/S relieves CsrA repression to induce transmission phenotypes by both FliA-dependent and -independent pathways. For L. pneumophila to avoid lysosomal degradation in macrophages, CsrA repression must be relieved by LetA/S before phagocytosis; conversely, before intracellular bacteria can replicate, CsrA repression must be restored. The reciprocal regulation of replication and transmission exemplified by CsrA likely enhances the fitness of microbes faced with fluctuating environments.     

6-Mer hyaluronan oligosaccharides increase IL-18 and IL-33 production in mouse synovial fibroblasts subjected to collagen-induced arthritis

Hyaluronan (HA) oligosaccharides stimulate pro-inflammatory responses in different cell types by modulating both cluster determinant 44 (CD44) and TLR4. The activation of these receptors is also mediated by collagen-induced arthritis (CIA) that, via two different pathways, culminates in the liberation of NF-κB. This then stimulates the production of pro-inflammatory cytokines, including IL-18 and IL-33, that are greatly involved in rheumatoid arthritis. The aim of this study was to investigate the effects of 6-mer HA oligosaccharides on mouse synovial fibroblasts obtained from normal DBA/J1 mice or mice subjected to CIA. Compared with normal synovial fibroblasts (NSF), rheumatoid arthritis synovial fibroblasts (RASF) showed no up-regulation of CD44 and TLR4 mRNA expression and the related proteins, as well as no activation of NF-κB. Very low levels of both mRNA and related proteins were also detected for IL-18 and IL-33. Treatment of NSF and RASF with 6-mer HA oligosaccharides significantly increased all the parameters in both fibroblast groups, although to a greater extent in RASF. The addition of hyaluronan binding protein to both NSF and RASF inhibited HA activity and was able to reduce the effects of 6-mer HA oligosaccharides and the consequent inflammatory response.     

A microfluorometric method for alkaline phosphatase: Application to the various segments of the nephron

A microtechnique has been developed for the measurement of alkaline phosphatase in minute amounts of renal tissue. This microtechnique utilizes the known fluorescent property of 4-methylumbelliferyl phosphate following enzymatic hydrolysis. The reaction is sensitive and reproducible and is inhibited by l-bromotetramisole, a specific alkaline phosphatase inhibitor. The microdetermination of alkaline phosphatase activity in the various segments of the mouse nephron allowed the localization of the enzyme in the glomeruli, and in the proximal convoluted tubule where the activity progressively decreases from the capsule of Bowman to the more distal segments. The enzyme was absent from the pars recta or S3 and from the rest of the nephron. This technique is applicable to very small amounts (0.1 μg of protein) of any tissue containing alkaline phosphatase.