Effect of cadmium stress on antioxidative enzymes during the germination of Serbian spruce [Picea omorika (Pan..) Purkynĕ]

When considering the effect of heavy metals on trees generally and on forest ecosystems especially,  importance is given to their influence on seed germination in metal polluted soil. There is insufficient data on  this subject, especially when conifers are concerned. In this work, the influence of high cadmium  concentrations on percentage germination, specific activities and isoenzyme patterns of catalase (CAT),  superoxide dismutase (SOD), and peroxidase (POD) during the germination of Serbian spruce [Picea omorika (Pan..) Purkynĕ] was studied. Cadmium chloride concentrations of up to 0.1 mM did not cause an inhibition of germination, while 1 mM concentration inhibited germination and the activities of catalase, superoxide  dismutase and peroxidase. The isoenzyme profile of catalase and superoxide dismutase did not change at high cadmium concentrations, while peroxidase expression of basic peroxidase (B5) with pI value of 9.1 increased. This isoform of POD can play an important role in the early development of Serbian spruce and its defense mechanism against heavy metals.Key words: Seed germination, catalase, peroxidase, superoxide dismutase, heavy metals

A Functional Nuclear Epidermal Growth Factor Receptor, Src and Stat3 Heteromeric Complex in Pancreatic Cancer Cells

Evidence is presented for the nuclear presence of a functional heteromeric complex of epidermal growth factor (EGFR), Src and the Signal Transducer and Activator of Transcription (Stat)3 proteins in pancreatic cancer cells. Stat3 remains nuclear and associated with Src or EGFR, respectively, upon the siRNA knockdown of EGFR or Src, demonstrating the resistance of the complex to the modulation of EGFR or Src alone. Significantly, chromatin immunoprecipitation (ChIP) analyses reveal the nuclear EGFR, Src and Stat3 complex is bound to the c-Myc promoter. The siRNA knockdown of EGFR or Src, or the pharmacological inhibition of Stat3 activity only marginally suppressed c-Myc expression. By contrast, the concurrent modulation of Stat3 and EGFR, or Stat3 and Src, or EGFR and Src strongly suppressed c-Myc expression, demonstrating that the novel nuclear heteromeric complex intricately regulates the c-Myc gene. The prevalence of the transcriptionally functional EGFR, Src, and Stat3 nuclear complex provides an additional and novel mechanism for supporting the pancreatic cancer phenotype and explains in part the insensitivity of pancreatic cancer cells to the inhibition of EGFR, Src or Stat3 alone

HERBICIDE PHOSPHINOTHRICIN CAUSES DIRECT STIMULATION HORMESIS

Herbicide phosphinothricin (PPT) inhibits glutamine synthetase (GS), a key enzyme in nitrogen assimilation, thus causing ammonia accumulation, glutamine depletion and eventually plant death. However, the growth response of Lotus corniculatus L. plants immersed in solutions with a broad range of PPT concentrations is biphasic, with pronounced stimulating effect on biomass production at concentrations ≤ 50 μM and growth inhibition at higher concentrations. The growth stimulation at low PPT concentrations is a result of activation of chloroplastic isoform GS2, while the growth suppression is caused by inhibition of both cytosolic GS1 and GS2 at higher PPT concentrations. Since the results are obtained in cell-free system (e.g. protein extracts), to which the principles of homeostasis are not applicable, this PPT effect is an unambiguous example of direct stimulation hormesis. A detailed molecular mechanism of concentration-dependent interaction of both PPT and a related GS inhibitor, methionine sulfoximine, with GS holoen- zymes is proposed. The mechanism is in concurrence with all experimental and literature data

A Facile Nanoparticle Immunoassay for Cancer Biomarker Discovery

<p>Abstract</p> <p>Background</p> <p>Gold nanoparticles (AuNPs) scatter light intensely at or near their surface plasmon wavelength region. Using AuNPs coupled with dynamic light scattering (DLS) detection, we developed a facile nanoparticle immunoassay for serum protein biomarker detection and analysis. A serum sample was first mixed with a citrate-protected AuNP solution. Proteins from the serum were adsorbed to the AuNPs to form a protein corona on the nanoparticle surface. An antibody solution was then added to the assay solution to analyze the target proteins of interest that are present in the protein corona. The protein corona formation and the subsequent binding of antibody to the target proteins in the protein corona were detected by DLS.</p> <p>Results</p> <p>Using this simple assay, we discovered multiple molecular aberrations associated with prostate cancer from both mice and human blood serum samples. From the mice serum study, we observed difference in the size of the protein corona and mouse IgG level between different mice groups (i.e., mice with aggressive or less aggressive prostate cancer, and normal healthy controls). Furthermore, it was found from both the mice model and the human serum sample study that the level of vascular endothelial growth factor (VEGF, a protein that is associated with tumor angiogenesis) adsorbed to the AuNPs is decreased in cancer samples compared to non-cancerous or less malignant cancer samples.</p> <p>Conclusion</p> <p>The molecular aberrations observed from this study may become new biomarkers for prostate cancer detection. The nanoparticle immunoassay reported here can be used as a convenient and general tool to screen and analyze serum proteins and to discover new biomarkers associated with cancer and other human diseases.</p

Serbian spruce, endemicity and advantages

Picea omorika (Pančić) Purkynĕ is Balkan endemic coniferous species and Tertiary relict of the European flora. Its natural habitat is fragmented and reduced to the middle and upper courses of the Drina River, in Western Serbia and Eastern Bosnia and Herzegovina. This region represents species long-term, cryptic and last refugium. The current limited natural range of Serbian spruce is mainly the result of the species poor competing ability. It retreats to areas less inhabitable by its competitors, predominantly Picea abies and Fagus orientalis. It inhabits open habitats, comprising cliffs and forest clearings, characterized by strong northerlywind, snow and rockfalls. Since the middle of the 19th century, its natural range declines continuously. Planting Serbian spruce outside its natural range has a long tradition, either as an ornamental tree species, or for afforestation, throughout Central and Northern Europe. Despite its endemism, P. omorika is considered as one of the most adaptable spruces. Wood properties are determined by cell arrangement, size and shape, and cell wall structure and thickness. Conifers, as a response to mechanical stress, such as wind and stem lean, form reaction wood called compression wood (CW). Its formation occurs on the lower side of the leaning stem, resulting in eccentric growth. Wood opposite to the CW in the same growth ring is termed opposite wood (OW), while wood from growth rings that do not contain any CW is termed normal wood (NW). CW is characterized by reduced tracheid length, rounder cell cross-sectional profile, presence of intercellular spaces, absence of the S3 cell wall layer and presence of helical cavities in S2 layer. Higher lignification, as one of the main characteristics of CW, is associated with changed lignin composition, increased amounts of phydroxyphenyl monomers and increased condensation of monomer units in the polymer. Consequently, CW contains less cellulose, with greatly increased amounts of galactan, and slightly lower amounts of mannan and xylan, and with higher angle of cellulose microfibrils in the S2 layer of the cell wall, compared to NW. CW occurs in a range of gradations from near NW to severe CW (SCW), mild CW (MCW) forming a continuum between NW and SCW. The degree of development of particular features of CW does not necessarily change in parallel to each other, so the severity of a given tracheid is represented as a function of the degrees of development of individual features, mainly lignification, helical cavities and cell wall thickness. Visual detection of compression wood severity, more precisely the determination of MCW, is difficult. As the severity of CW affects mechanical and chemical properties of wood in forest products industry it is desirable to be able to measure CW severity. We developed different morphometric and non-morphometric methods for distinguishing wood samples on a compression severity scale. They are based on tracheid double wall thickness, cellulose microfibrils order (distribution and alignment of cellulose microfibrils), or variation in lignin structure. We used confocal fluorescence microscopy and spectroscopy, and fluorescence-detected linear dichroism (FDLD) microscopy, combined with development of new algorithms and statistical analysis. We tested our methods on stem samples of P. omorika juvenile trees exposed to long term static bending. P. omorika belongs to slow-growing conifer species in which CW typically occurs in a severe form, while juvenile conifer wood is characterized by randomly distributed MCW, NW often being absent. These are the features that suggest P. omorika juvenile wood a good choice of samples for evaluation of the precision of methods suggested for estimation of compression wood severity. Our methods for distinguishing wood samples on a compression severity scale provide a fine gradation of juvenile P. omorika wood samples from NW to the severest form of CW, compression severity scales being partially different. The presented results qualify our methods for use in estimation of compression wood severity in forest products industries, individually or in combination, and confirm juvenile P. omorika stem samples as a good choice of samples for evaluation of the precision of methods suggested for compression wood severity estimation

Serbian spruce (Picea omorika (Pančić) Purkyné) - endemicity and advantages

Conifers, as a response to mechanical stress, such as wind and stem lean, form reaction wood called compression wood (CW). CW occurs in a range of gradations from near normal wood (NW) to severe CW (SCW). As the severity of CW affects the mechanical and chemical properties of wood, and as CW has limited value in the forest products industry, it is desirable to be able to measure CW severity. Picea omorika belong to slow-growing conifer species in which CW typically occurs in a severe form. We developed different morphometric and non-morphometric methods for estimation of CW severity tested on wood samples of P. omorika juvenile trees exposed to long term static bending. This specific review is aimed at presenting P. omorika as one of the most adaptable spruces, and as a good model for testing of methods for estimation of compression wood severity. First, we summarize main knowledge about P. omorika, features of CW, and methods for assessment of wood quality. Then, we present breifly our recently published methods for estimation of compression wood severity tested on P. omorika juvenile wood samples.Konifere kao odgovor na mehanički stres (vetar, savijanje) formiraju reakciono drvo koje se naziva kompresiono drvo (CW). CW se javlja u nizu gradacija od skoro normalnog drveta (NW) do jako izraženog CW (SCW). S obzirom da stepen izraženosti osobina CW ima značajan uticaj na mehaničke i hemijske osobine drveta i da CW ima ograničenu vrednost za drvnu industriju, poželjno je moći odrediti stepen izraženosti osobina CW u uzorku. Picea omorika spada u sporo rastuće četinarske vrste kod kojih se CW tipočno javlja u jako izraženoj formi. Mi smo razvili nekoliko morfometrijskih i ne-morfometrijskih metoda za procenu izraženosti osobina CW u uzorku, testiranih na uzorcima drveta juvenilnih stabala P. omorika koja su bila izložena dugotajnom statičkom savijanju. Ovaj revijski rad ima za cilj da predstavi Pančićevu omoriku kao jednu od najadaptabilnijih smrča i kao dobar model za testiranje metoda za procenu izraženosti osobina CW u uzorku. U prvom delu sumiramo znanja o Pančićevoj omorici, osobinama CW i metodama za procenu kvaliteta drveta, a u drugom ukratko predstavljamo naše nedavno objavljene metode za za procenu izraženosti osobina CW u uzorku, testirane na uzorcima drveta juvenilnih stabala P. omorika

Changes in sclerenchyma cell walls related to stem twining in Dioscorea balcanica

Dioscorea balcanica Košanin, family Dioscoreaceae, is an endemic, endangered liana species and a Tertiary relict of Balkan Peninsula. Gelatinous fibers, specialized sclerenchyma cells and well-known components of tension wood, are responsible for stem twining in liana plants. The aim of this investigation was to determine changes in sclerenchyma cell walls correlated with the twining process in liana plants. Our results showed that the differences in cell walls of sclerenchyma cells between straight and twisted internodes are not visible by light microscopy, but they are visible by SEM microscopy. In twisted internodes, cell walls of sclerenchyma cells in the region of contact with the support (‘‘tension’’ side of twisted internodes) appear smooth on the cross sections, suggesting cellulose microfibrils oriented almost parallel to the fiber axis. In contrast, cell walls of the entire ring of sclerenchyma cells in straight internodes, as well as cell walls of sclerenchyma cells on the “opposite” side of twisted internodes, appear jagged on the cross sections, suggesting cellulose microfibrils oriented at very high microfibril angle to the fiber axis. This result suggests that gelatinous fibers in D. balcanica stem have lignified G-layer, and thus could contribute to the understanding of ‘‘late lignification of the G-layer’’

Klijanja semena Pančićeve omorike (Picea omorika (Pančić) Purkyně) i antioksidativni enzimi

Pančićeva omorika predstavlja Balkansku endemičnu vrstu smrče i tercijarni relikt. Određen je sastav antioksidativnih enzima tokom klijanja semena omorike u fiziološkim uslovima, a radi boljeg razumevanja mehanizama otpornosti na zagađivače iz spoljašnje sredine.1 Ovo je prva studija aktivnosti enzima katalaze (CAT), superoksid dismutaze (SOD) i peroksidaze (POD) tokom klijanja dve linije semena Pančićeve omorike (A – borealis i S – srpska). Klijanje semena je praćeno tokom 7 dana. Za procenat klijavosti korišćen je proboj radikule za više od 1 milimetar kao kriterijum. Linija A je pokazala veći procenat klijavosti (74%) i veću aktivnost enzima po jedinici sveže mase klijanaca u poređenju sa linijom S (63%). CAT aktivnost kod linije A je povećana po jedinici mase klijanaca i suvih semena, a nakon 7 dana kod neisklijalih semena nije detektovana. SOD aktivnost je ostala na sličnom nivou u obe linije. Aktivnost POD na početku nije detektovana, ali se naglo povećala nakon četvrtog dana da bi sedmog bila 10 U/g sveže mase klijanaca kod linije S i 28 U/g kod A. CAT i SOD su uključeni u očuvanje klijavosti semena i imaju ulogu zaštite od reaktivnih kiseoničnih vrsta tokom skladištenja i klijanja, dok je katalazna aktivnost bitna za procenu klijavosti. Najveću promenu aktivnosti za vreme klijanja pokazala je peroksidaza, čija aktivnost nije detektovana u suvim semenima, a tokom klijanja naglo se povećala i značajna je u kasnijim fazama klijanja