Extensive Basal Level Activation of Complement Mannose-Binding Lectin-Associated Serine Protease-3: Kinetic Modeling of Lectin Pathway Activation Provides Possible Mechanism

Serine proteases (SPs) are typically synthesized as precursors, termed proenzymes or zymogens, and the fully active form is produced via limited proteolysis by another protease or by autoactivation. The lectin pathway of the complement system is initiated by mannose-binding lectin (MBL)-associated SPs (MASP)-1, and MASP-2, which are known to be present as proenzymes in blood. The third SP of the lectin pathway, MASP-3, was recently shown to be the major activator, and the exclusive "resting blood" activator of profactor D, producing factor D, the initiator protease of the alternative pathway. Because only activated MASP-3 is capable of carrying out this cleavage, it was presumed that a significant fraction of MASP-3 must be present in the active form in resting blood. Here, we aimed to detect active MASP-3 in the blood by a more direct technique and to quantitate the active to zymogen ratio. First, MASPs were partially purified (enriched) from human plasma samples by affinity chromatography using immobilized MBL in the presence of inhibitors. Using this MASP pool, only the zymogen form of MASP-1 was detected by Western blot, whereas over 70% MASP-3 was in an activated form in the same samples. Furthermore, the active to zymogen ratio of MASP-3 showed little individual variation. It is enigmatic how MASP-3, which is not able to autoactivate, is present mostly as an active enzyme, whereas MASP-1, which has a potent autoactivation capability, is predominantly proenzymic in resting blood. In an attempt to explain this phenomenon, we modeled the basal level fluid-phase activation of lectin pathway proteases and their subsequent inactivation by C1 inhibitor and antithrombin using available and newly determined kinetic constants. The model can explain extensive MASP-3 activation only if we assume efficient intracomplex activation of MASP-3 by zymogen MASP-1. On the other hand, the model is in good agreement with the fact that MASP-1 and -2 are predominantly proenzymic and some of them is present in the form of inactive serpin-protease complexes. As an alternative hypothesis, MASP-3 activation by proprotein convertases is also discussed

The sensitivity of herbaceous plants to light Pollution = A lágyszárú fajok érzékenysége a fényszennyezésre

Plants living near street lights in temperate zones are good examples of the effect of light pollution with a marked shift in leaf fall and bud breaking. Low intensity light (light pollution) is not sufficient for photosynthesis, but can cause changes in many physiological processes, moreover, it can have a disrupting effect on the plant and its connected ecosystem. In this study, physiological effects of light pollution on leaf morphology, leaf anatomy, and photosynthesis were investigated in the herbaceous species Erigeron annuus (L.) Pers. and Fallopia x bohemica (Chrtek et Chrtková) J.P. Bailey under conventional HPS and LED illumination. In our experience, HPS lamps supported the photosynthetic activity of the studied species, the growth of palisade tissue cells. Light pollution of LED lamps reduced net photosynthesis in both species compared to non-light-polluted leaves. ----- A LÁGYSZÁRÚ FAJOK ÉRZÉKENYSÉGE A FÉNYSZENNYEZÉSRE A mérsékel t égöv i utcai lámpák közelében él ő növények a fényszennyezés hatását jól szemléltetik a levélhullás és rügyfakadás szembetűnő eltolódásával. A gyengébb intenzitású fény nem elegendő a fotoszintézishez, de számos élettani folyamat megváltoztatását idézheti elő, zavart okozva a növény és a vele kapcsolatban álló élőlények életében is. Vizsgálataink során az Erigeron annuus (L.) Pers. és a Fallopia x bohemica (Chrtek et Chrtková) J. P. Bailey lágyszárú fajok fényszennyezésre bekövetkező levélmorfológiai, levélanatómiai és fotoszintézis élettani változásait vizsgáltuk hagyományos HPS- és LED-megvilágítás mellett. A HPS-lámpák tapasztalataink szerint támogatják a vizsgált fajok fotoszintetikus aktivitását, a paliszád szövet sejtjeinek növekedését. A LED-lámpák fényszennyezése mindkét faj esetében csökkentette a nettó fotoszintézist a nem fényszennyezett levelekhez képest

The sensitivity of herbaceous plants to light Pollution

Plants living near street lights in temperate zones are good examples of the effect of light pollution with a marked shift in leaf fall and bud breaking. Low intensity light (light pollution) is not sufficient for photosynthesis, but can cause changes in many physiological processes, moreover, it can have a disrupting effect on the plant and its connected ecosystem. In this study, physiological effects of light pollution on leaf morphology, leaf anatomy, and photosynthesis were investigated in the herbaceous species Erigeron annuus (L.) Pers. and Fallopia x bohemica (Chrtek et Chrtková) J.P. Bailey under conventional HPS and LED illumination. In our experience, HPS lamps supported the photosynthetic activity of the studied species, the growth of palisade tissue cells. Light pollution of LED lamps reduced net photosynthesis in both species compared to non-light-polluted leaves. ----- A LÁGYSZÁRÚ FAJOK ÉRZÉKENYSÉGE A FÉNYSZENNYEZÉSRE A mérsékel t égöv i utcai lámpák közelében él ő növények a fényszennyezés hatását jól szemléltetik a levélhullás és rügyfakadás szembetűnő eltolódásával. A gyengébb intenzitású fény nem elegendő a fotoszintézishez, de számos élettani folyamat megváltoztatását idézheti elő, zavart okozva a növény és a vele kapcsolatban álló élőlények életében is. Vizsgálataink során az Erigeron annuus (L.) Pers. és a Fallopia x bohemica (Chrtek et Chrtková) J. P. Bailey lágyszárú fajok fényszennyezésre bekövetkező levélmorfológiai, levélanatómiai és fotoszintézis élettani változásait vizsgáltuk hagyományos HPS- és LED-megvilágítás mellett. A HPS-lámpák tapasztalataink szerint támogatják a vizsgált fajok fotoszintetikus aktivitását, a paliszád szövet sejtjeinek növekedését. A LED-lámpák fényszennyezése mindkét faj esetében csökkentette a nettó fotoszintézist a nem fényszennyezett levelekhez képest

Szerzői kapcsolatháló-elemzés a családi gazdálkodásokról szóló publikációk alapján

During our research, we analysed the social network of authors written articles on family farming. Based on the definition of the network analysis, we did this on a macro level, because it analyses the relationships between individuals and interactions between them. The sample is based on 254 scientific papers written on this topic between 1976 and 2016. We will show you the coauthorship network. In our research, we sought to find out why network analysis can be useful and who are the most important actors in the network

Szerzői kapcsolatháló-elemzés a családi gazdálkodásokról szóló publikációk alapján

During our research, we analysed the social network of authors written articles on family farming. Based on the definition of the network analysis, we did this on a macro level, because it analyses the relationships between individuals and interactions between them. The sample is based on 254 scientific papers written on this topic between 1976 and 2016. We will show you the coauthorship network. In our research, we sought to find out why network analysis can be useful and who are the most important actors in the network.Kutatásunk során a családi gazdálkodásról szóló cikkek szerzőinek kapcsolati hálózatát elemeztük. A kapcsolatháló elemzés definíciója alapján makro szinten tettük ezt, hiszen ez vizsgálja az egyének közötti kapcsolatokat, illetve a közöttük lévő interakciókat. A minta alapját az 1976-2016 között ebben a témában írt 254 tudományos cikk adja. A cikkben a szerzői kapcsolatokat ábrázoló hálót mutatjuk be. Kutatásunkban arra kerestük a választ, hogy miért lehet hasznos a kapcsolatháló­elemzés, illetve kik a legfontosabb szereplők a hálóban

Vibrations of fixed-fixed heterogeneous curved beams loaded by a central force at the crown point

This paper addresses the vibrations of heterogeneous curved beams under the assumption that the load of the beam is a dead one and is perpendicular to the centroidal axis. It is assumed that: (a) the radius of curvature is constant, and (b) Young’s modulus and the Poisson’s number depend on the cross-sectional coordinates. As for the issue of fixed-fixed beams, the objectives are the following: (1) to determine the Green’s function matrices provided that the beam is under radial load; (2) to examine how the load affects the natural frequencies given that the beam is subjected to a vertical force at the crown point; (3) to develop a numerical model which makes it possible to determine how the natural frequencies are related to the load. The computational results are presented graphically

Quantification of the zymogenicity and the substrate-induced activity enhancement of complement factor D

Complement factor D (FD) is a serine protease present predominantly in the active form in circulation. It is synthesized as a zymogen (pro-FD), but it is continuously converted to FD by circulating active MASP-3. FD is a unique, self-inhibited protease. It has an extremely low activity toward free factor B (FB), while it is a highly efficient enzyme toward FB complexed with C3b (C3bB). The structural basis of this phenomenon is known; however, the rate enhancement was not yet quantified. It has also been unknown whether pro-FD has any enzymatic activity. In this study, we aimed to measure the activity of human FD and pro-FD toward uncomplexed FB and C3bB in order to quantitatively characterize the substrate-induced activity enhancement and zymogenicity of FD. Pro-FD was stabilized in the proenzyme form by replacing Arg25 (precursor numbering) with Gln (pro-FD-R/Q). Activated MASP-1 and MASP-3 catalytic fragments were also included in the study for comparison. We found that the complex formation with C3b enhanced the cleavage rate of FB by FD approximately 20 million-fold. C3bB was also a better substrate for MASP-1, approximately 100-fold, than free FB, showing that binding to C3b renders the scissile Arg-Lys bond in FB to become more accessible for proteolysis. Though easily measurable, this cleavage by MASP-1 is not relevant physiologically. Our approach provides quantitative data for the two-step mechanism characterized by the enhanced susceptibility of FB for cleavage upon complex formation with C3b and the substrate-induced activity enhancement of FD upon its binding to C3bB. Earlier MASP-3 was also implicated as a potential FB activator; however, MASP-3 does not cleave C3bB (or FB) at an appreciable rate. Finally, pro-FD cleaves C3bB at a rate that could be physiologically significant. The zymogenicity of FD is approximately 800, i.e., the cleavage rate of C3bB by pro-FD-R/Q was found to be approximately 800-fold lower than that by FD. Moreover, pro-FD-R/Q at approximately 50-fold of the physiological FD concentration could restore half-maximal AP activity of FD-depleted human serum on zymosan. The observed zymogen activity of pro-FD might be relevant in MASP-3 deficiency cases or during therapeutic MASP-3 inhibition

Cutting Edge: A New Player in the Alternative Complement Pathway, MASP-1 Is Essential for LPS-Induced, but Not for Zymosan-Induced, Alternative Pathway Activation

The complement system is a sophisticated network of proteases. In this article, we describe an unexpected link between two linear activation routes of the complement system: the lectin pathway (LP) and the alternative pathway (AP). Mannose-lectin binding-associated serine protease (MASP)-1 is known to be the initiator protease of the LP. Using a specific and potent inhibitor of MASP-1, SGMI-1, as well as other MASP-1 inhibitors with different mechanisms of action, we demonstrated that, in addition to its functions in the LP, MASP-1 is essential for bacterial LPS-induced AP activation, whereas it has little effect on zymosan-induced AP activation. We have shown that MASP-1 inhibition prevents AP activation, as well as attenuates the already initiated AP activity on the LPS surface. This newly recognized function of MASP-1 can be important for the defense against certain bacterial infections. Our results also emphasize that the mechanism of AP activation depends on the activator surface