Activation of GABA‐A receptor ameliorates homocysteine‐induced MMP‐9 activation by ERK pathway

Hyperhomocysteinemia (HHcy) is a risk factor for neuroinflammatory and neurodegenerative diseases. Homocysteine (Hcy) induces redox stress, in part, by activating matrix metalloproteinase‐9 (MMP‐9), which degrades the matrix and leads to blood–brain barrier dysfunction. Hcy competitively binds to γ‐aminbutyric acid (GABA) receptors, which are excitatory neurotransmitter receptors. However, the role of GABA‐A receptor in Hcy‐induced cerebrovascular remodeling is not clear. We hypothesized that Hcy causes cerebrovascular remodeling by increasing redox stress and MMP‐9 activity via the extracellular signal‐regulated kinase (ERK) signaling pathway and by inhibition of GABA‐A receptors, thus behaving as an inhibitory neurotransmitter. Hcy‐induced reactive oxygen species production was detected using the fluorescent probe, 2′–7′‐dichlorodihydrofluorescein diacetate. Hcy increased nicotinamide adenine dinucleotide phosphate‐oxidase‐4 concomitantly suppressing thioredoxin. Hcy caused activation of MMP‐9, measured by gelatin zymography. The GABA‐A receptor agonist, muscimol ameliorated the Hcy‐mediated MMP‐9 activation. In parallel, Hcy caused phosphorylation of ERK and selectively decreased levels of tissue inhibitors of metalloproteinase‐4 (TIMP‐4). Treatment of the endothelial cell with muscimol restored the levels of TIMP‐4 to the levels in control group. Hcy induced expression of iNOS and decreased eNOS expression, which lead to a decreased NO bioavailability. Furthermore muscimol attenuated Hcy‐induced MMP‐9 via ERK signaling pathway. These results suggest that Hcy competes with GABA‐A receptors, inducing the oxidative stress transduction pathway and leading to ERK activation. J. Cell. Physiol. 220: 257–266, 2009. © 2009 Wiley‐Liss, Inc.     

Esterases as a marker for growth of BY-2 tobacco cells and early somatic embryos of the Norway spruce

Growth is one of the basic properties of biological systems. The methods which are commonly used for the determination of growth are usually difficult and not very accurate. In the present work we decided to use esterase activity as a growth marker in tobacco suspension culture (BY-2 line) and in early somatic embryos of Norway spruce (clone 2/32) grown on a semi-solid medium. Esterase activity correlates well with the classical growth characteristics of BY-2 and spruce early somatic embryos. Determination of esterase activity is based on spectrophotometric and spectrofluorimetric detection of reaction products, which arise from the enzymatic hydrolysis of two substrates (p -nitrophenyl acetate and fluorescein diacetate) by esterase. The spectrophotometric method enabled us to detect approximately 10⁴ BY-2 cells and 25 spruce embryos whereas the more sensitive spectrofluorimetric method allowed us to detect approximately 800 BY-2 cells and 5 early somatic embryos of Norway spruce.     

Improved Cultivation Systems for Isolation of the Colorado Potato Beetle Spiroplasma

In North America, the Colorado potato beetle, Leptinotarsa decemlineata, is often infected with the host-specific, gut-inhabiting Colorado potato beetle spiroplasma (CPBS). CPBS is apparently a commensal, but it may be useful in biocontrol if it can be transformed to express an insect-lethal gene. Difficulty in cultivating the organism, however, has hindered the development of a suitable transformation system. In this study, we eliminated the need for coculturing CPBS with insect cells. CPBS was reliably isolated with the BBL Anaerobic GasPak Jar system (low redox, enhanced CO(inf2)), which was easier to use and less expensive than insect cell coculture methods. A further advantage is a reduction in contaminating insect cell components. Use of anaerobiosis should facilitate early-passage screening of isolates for extrachromosomal elements, for use in gene vector constructs. The unique spiral (decreasing amplitude of coils) morphology of CPBS was preserved by anaerobiosis. The use of low-pH (6.0 to 6.5) media allowed aerobic adaptation of CPBS to M1D and SP-4 broth media. These formulations permitted the first cultivation of CPBS on solid media, an accomplishment that will simplify the selection of molecular transformants. Potato beetles collected at four sites in Poland yielded CPBS strains similar to those previously obtained from populations in North America.     

Selective enzymic esterification of free fatty acids with n-butanol under microwave irradiation and under classical heating

Selective enzymic esterification of free fatty acids, obtained from blackcurrant oil by chemical saponification, with n-butanol using four immobilized lipases under microwave irradiation and under classical heating was studied. A positive effect of microwave irradiation on chemical yields of the products of the enzymic reactions and specificity of lipases were observed in comparison with a controlled heating in an incubator equipped with shaking (classical heating) applied during the identical enzyme-mediated processes. The maximum quantity of -linolenic acid (30%) was obtained with Lipozyme used as biocatalyst of the reaction under microwave irradiation. The maximum quantity of butyl -linolenate (20%) was obtained by a Pseudomonas cepacia lipase catalyzed esterification under classical heating.     

An overview of malaria transmission from the perspective of Amazon Anopheles vectors

In the Americas, areas with a high risk of malaria transmission are mainly located in the Amazon Forest, which extends across nine countries. One keystone step to understanding the Plasmodium life cycle in Anopheles species from the Amazon Region is to obtain experimentally infected mosquito vectors. Several attempts to colonise Ano- pheles species have been conducted, but with only short-lived success or no success at all. In this review, we review the literature on malaria transmission from the perspective of its Amazon vectors. Currently, it is possible to develop experimental Plasmodium vivax infection of the colonised and field-captured vectors in laboratories located close to Amazonian endemic areas. We are also reviewing studies related to the immune response to P. vivax infection of Anopheles aquasalis, a coastal mosquito species. Finally, we discuss the importance of the modulation of Plasmodium infection by the vector microbiota and also consider the anopheline genomes. The establishment of experimental mosquito infections with Plasmodium falciparum, Plasmodium yoelii and Plasmodium berghei parasites that could provide interesting models for studying malaria in the Amazonian scenario is important. Understanding the molecular mechanisms involved in the development of the parasites in New World vectors is crucial in order to better determine the interaction process and vectorial competence.     

Refining the late Silurian sea-level history of the Prague Syncline—a case study based on the Přídolí GSSP (Czech Republic)

A 50-m-thick section in the Po?áry quarry, Prague Syncline (Czech Republic) spanning the upper Silurian (uppermost Ludlow and P?ídolí) to the lowermost Devonian (Lochkovian) has been studied using sedimentological and physical stratigraphical (gamma-ray spectrometry) methods combined with conodont biostratigraphy. Conodont data demonstrate the presence of local conodont biozones: “Ozarkodina” crispa (uppermost Ludlow)—Zieglerodina zellmeri (base of P?ídolí)—Zieglerodina ivochlupaci—Delotaxis detorta—“Ozarkodina” eosteinhornensis s.s.—Zieglerodina klonkensis—Icriodus hesperius-optima (lowermost Lochkovian). The studied section represents a transgressive–regressive facies succession characterized by a transition from distal calciturbidites deposited in a distally steepened carbonate platform during transgression and sea-level highstand (crispa to lower ivochlupaci zones) to mixed calciturbidites/coarse-grained bioclastic limestones (falling-stage systems tract, upper ivochlupaci to lower klonkensis zones). The upper part of the succession consists of bioclastic limestones corresponding to a subtidal setting between storm-wave and fair-weather wave base (lowstand systems tract in upper klonkensis and hesperius-optima zones). This interpretation corresponds to the late Silurian global sea-level pattern as recorded in other regions. Thus the depositional system is interpreted as mostly driven by eustasy with short-lived periods of influence from local tectonics.     

Modeling individual tree height to diameter ratio for Norway spruce and European beech in Czech Republic

Key message

The purposed spatially explicit and spatially non-explicit height to diameter ratio models can be useful to evaluate the stability of trees and stands for Norway spruce and European beech forests.

Abstract

Height to diameter ratio (HDR) is an individual tree index, also known as slenderness coefficient, and commonly used to evaluate stability of trees and stands. We developed both spatially explicit and spatially non-explicit HDR models for Norway spruce (Picea abies (L.) Karst.) and European beech (Fagus sylvatica L.) using a large dataset collected from fully stem-mapped permanent research plots in various parts of the Czech Republic. Various tree and stand characteristics were evaluated for their potential contributions to the the HDR models. In addition to diameter at breast height (DBH), other highly significant predictor variables identified are dominant height (HDOM) (site quality measure), dominant diameter (DDOM) and quadratic mean diameter (QMD) (spatially non-explicit competition measures), and Hegyi’s index (spatially explicit competition index, CI). A simple exponential decay function was chosen as a base function to include these predictor variables. Both spatially explicit and spatially non-explicit models described large parts of the HDR variations [R _adj ²  = 0.66 (Norway spruce), 0.72 (European beech)] without any systematic deviation of the residuals across the observed data range. Unlike for European beech, spatially explicit model for Norway spruce better described HDR variations than its spatially non-explicit counterpart. After DBH, HDOM provided the largest contribution to each model type, followed by DDOM and QMD or CI for both species. The HDR increased with increasing HDOM and CI, but it decreased with increasing DDOM and QMD, suggesting there were significantly large effects of site quality and stand density on HDR. Because of a little difference between the fit statistics and graphical displays of the two model types, spatially non-explicit model is recommended for prediction of HDR for both species as this model does not require spatially explicit CI, which is computationally much more complex than spatially non-explicit competition measures. The proposed HDR models may be applicable to assess stability of trees and stands, and to regulate stand densities.

     

Dynamic pressure method for kla measurement in large-scale bioreactors

A dynamic method is proposed for k(l)a measurement in aerated and agitated reactors, in which a change in the total pressure in the reactor by approximately 20% leads to a simultaneous change in the oxygen concentration in all the bubbles in the dispersion. This procedure suppresses the influence of nonideal mixing of the gas phase on the k(l)a value. Other dynamic methods so far used do not possess this advantage. They are based on a step change in oxygen concentration in the entering gas, where the interfacial nitrogen transport and the finite rate of the concentration change propagation into the individual bubbles in the dispersion can cause an error in the reported k(l)a values of more than hundreds of percent. The reliability of the pressure method is tested by comparison both with the standard dynamic method, in which pure oxygen is absorbed in a liquid from which all other gas components were previously removed, and with the steady-state sulphite method. The signal of the oxygen probe used in the experiments must be independent of the pressure. A test for this in dependence is described. The pressure method is also suitable for large-scale reactors since the necessary pressure changes are sufficiently small and, morever, air can be used.