Plant immune responses triggered by beneficial microbes

Beneficial soil-borne microorganisms, such as plant growth promoting rhizobacteria and mycorrhizal fungi, can improve plant performance by inducing systemic defense responses that confer broad-spectrum resistance to plant pathogens and even insect herbivores. Different beneficial microbe-associated molecular patterns (MAMPs) are recognized by the plant, which results in a mild, but effective activation of the plant immune responses in systemic tissues. Evidence is accumulating that systemic resistance induced by different beneficials is regulated by similar jasmonate-dependent and ethylene-dependent signaling pathways and is associated with priming for enhanced defense.     

The past and present occurrence of <Emphasis Type="Italic">Elatine</Emphasis> and implications for palaeoenvironmental reconstructions

The past and present occurrence of Elatine hydropiper L. (eight-stamened waterwort), E. hexandra (Lapierre) DC. (six-stamened waterwort) and E. triandra Schkuhr (three-stamened waterwort) in the Netherlands is discussed. It has proved possible to distinguish the slightly curved seeds of E. hexandra and E. triandra in subfossil material on morphological grounds. E. hexandra is the most common species at present, but subfossil finds are confined to Late-glacial and Pre-boreal sediments of one lake in the Pleistocene area of the Netherlands. Living plants of E. triandra have only been found in the Netherlands in 1838–1839, but there are 17 records from five archaeological sites, all located in the western Dutch estuarine area. Several of these sites also yielded E. hydropiper, archaeobotanically the most common species. The occurrence of E. triandra and E. hydropiper in the Netherlands seems to have been favoured by high summer temperatures. The ecological amplitude of this combination of species gives firm clues for the reconstruction of the environment, which must have been a freshwater tidal area. Since this type of environment is strongly threatened on a worldwide scale, the presence of these species in the past may also provide interesting information for present nature development projects in the Dutch estuarine area.     

Environment affects stress in exercised turbot

We investigated the interaction of water temperature (10, 18 and 22 degrees C) and salinity (33.5 and 15 per thousand ) on the stress response of juvenile turbot. At each temperature/salinity combination, fish were subjected to 10 min enforced exercise. This induced a moderate stress response, which differed at the various temperature and salinity combinations. High temperatures caused more rapid increases in plasma cortisol and glucose, larger and more rapid increases in plasma lactate levels, which were also influenced by body weight, and a faster recovery in plasma Na(+) and Cl(-). Low salinity ameliorated cortisol responses at low but not at high temperatures. The magnitude of ionic disturbance was reduced at 15 per thousand. Plasma K(+) did not change at any temperature or salinity. The stress response involved activation of the brain-pituitary-interrenal axis, as indicated by the cortisol elevations. The low magnitude of glucose responses, the mild Na(+) and Cl(-) disturbances, and the lacking K(+)-responses indicated mild activation of the brain-sympathetic-chromaffin cell axis, and hence a low release of catecholamines, which seemed though to occur to a higher extent at higher temperatures. The relatively low catecholaminergic response of turbot may be linked to their inactive sedentary lifestyle. The higher responsiveness at higher water temperatures may reflect a higher overall adaptive capacity.     

Effects of acetylsalicylic acid treatment on thyroid hormones,prolactins, and the stress response of tilapia (Oreochromis mossambicus)

The cyclooxygenase (COX) pathway converts arachidonic acid (ArA) into prostaglandins (PGs), which interact with the stress response in mammals and possibly in fish as well. Acetylsalicylic acid (ASA) is a COX inhibitor and was used to characterize the effects of PGs on the release of several hormones and the stress response of tilapia (Oreochromis mossambicus). Plasma PGE2 was significantly reduced at 100 mg ASA/kg body wt, and both basal PGE2 and cortisol levels correlated negatively with plasma salicylate. Basal plasma 3,5,3'-triiodothyronine (T3) was reduced by ASA treatment, whereas prolactin (PRL)188 increased at 100 mg ASA/kg body wt. ASA depressed the cortisol response to the mild stress of 5 min of net confinement. As expected, glucose and lactate were elevated in the stressed control fish, but the responses were blunted by ASA treatment. Gill Na+-K+-ATPase activity was not affected by ASA. Plasma osmolarity increased after confinement in all treatments, whereas sodium only increased at the high ASA dose. This is the first time ASA has been administered to fish in vivo, and the altered hormone release and the inhibition of the acute stress response indicated the involvement of PGs in these processes.     

A family of human Y chromosomes has dispersed throughout northern Eurasia despite a 1.8-Mb deletion in the azoospermia factor c region

The human Y chromosome is replete with amplicons-very large, nearly identical repeats-which render it susceptible to interstitial deletions that often cause spermatogenic failure. Here we describe a recurrent, 1.8-Mb deletion that removes half of the azoospermia factor c (AZFc) region, including 12 members of eight testis-specific gene families. We show that this "b2/b3" deletion arose at least four times in human history-likely on inverted variants of the AZFc region that we find exist as common polymorphisms. We observed the b2/b3 deletion primarily in one family of closely related Y chromosomes-branch N in the Y-chromosome genealogy-in which all chromosomes carried the deletion. This branch is known to be widely distributed in northern Eurasia, accounts for the majority of Y chromosomes in some populations, and appears to be several thousand years old. The population-genetic success of the b2/b3 deletion is surprising, (i) because it removes half of AZFc and (ii) because the gr/gr deletion, which removes a similar set of testis-specific genes, predisposes to spermatogenic failure. Our present findings suggest either that the b2/b3 deletion has at most a modest effect on fitness or that, within branch N, its effect has been counterbalanced by another genetic, possibly Y-linked, factor.     

Rapid assay to detect possible natural substrates of proteases in living cells

Proteolysis is a regulatory step in many physiological processes, but which proteases in what cellular sites are involved in activation or degradation of which peptides is not well known. We developed a rapid assay consisting of living cells and fluorogenic protease substrates to determine which bioactive peptides are possible natural substrates of a specific protease with the multifunctional or moonlighting protein CD26/dipeptidyl peptidase IV (DPPIV) as a model. CD26/DPPIV catalyzes cleavage of peptides from the amino terminus of peptides with proline at the penultimate position. Many biologically active peptides, such as beta-casomorphin1-5, contain proline in the penultimate position. We incubated living Jurkat cells, which are T cells that lack CD26/DPPIV, and CD26/DPPIV-transfected Jurkat cells in the presence of the fluorogenic substrate [Ala-Pro]2-cresyl violet (Magic Red) and beta-casomorphin1-5. Fluorescent cresyl violet was generated by CD26/DPPIV-transfected Jurkat cells but not by wild-type Jurkat cells with a Km of 3.7 microM. beta-Casomorphin1-5 appeared to be a possible natural substrate of CD26/DPPIV, because it inhibited production of fluorescence competitively (Ki = 60 microM). The assay using living cells and a fluorogenic protease substrate is an efficient system to determine whether specific peptides are possible natural substrates of a particular protease.     

Rectal Organoids Enable Personalized Treatment of Cystic Fibrosis

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Flavaglines Stimulate Transient Receptor Potential Melastatin Type 6 (TRPM6) Channel Activity

Magnesium (Mg²⁺) is essential for enzymatic activity, brain function and muscle contraction. Blood Mg²⁺ concentrations are tightly regulated between 0.7 and 1.1 mM by Mg²⁺ (re)absorption in kidney and intestine. The apical entry of Mg²⁺ in (re)absorbing epithelial cells is mediated by the transient receptor potential melastatin type 6 (TRPM6) ion channel. Here, flavaglines are described as a novel class of stimulatory compounds for TRPM6 activity. Flavaglines are a group of natural and synthetic compounds that target the ubiquitously expressed prohibitins and thereby affect cellular signaling. By whole-cell patch clamp analyses, it was demonstrated that nanomolar concentrations of flavaglines increases TRPM6 activity by ∼2 fold. The stimulatory effects were dependent on the presence of the alpha-kinase domain of TRPM6, but did not require its phosphotransferase activity. Interestingly, it was observed that two natural occurring TRPM6 mutants with impaired insulin-sensitivity, TRPM6-p.Val1393Ile and TRPM6-p.Lys1584Glu, are not sensitive to flavagline stimulation. In conclusion, we have identified flavaglines as potent activators of TRPM6 activity. Our results suggest that flavaglines stimulate TRPM6 via the insulin receptor signaling pathway.