1. Transcriptome-informed identification and characterization of Planococcus citri cis- and trans-isoprenyl diphosphate synthase genesMojca Juteršek, Iryna Gerasymenko, Marko Petek, Kristina Gruden, Špela Baebler, 2024, original scientific article Abstract: Insect physiology and reproduction depend on several terpenoid compounds, whose biosynthesis is mainly unknown. One enigmatic group of insect monoterpenoids are mealybug sex pheromones, presumably resulting from the irregular coupling activity of unidentified isoprenyl diphosphate synthases (IDSs). Here, we performed a comprehensive search for IDS coding sequences of the pest mealybug Planococcus citri. We queried the available genomic and newly generated short- and long-read P. citri transcriptomic data and identified 18 putative IDS genes, whose phylogenetic analysis indicates several gene family expansion events. In vitro testing confirmed regular short-chain coupling activity with five gene products. With the candidate with highest IDS activity, we also detected low amounts of irregular coupling products, and determined amino acid residues important for chain-length preference and irregular coupling activity. This work therefore provides an important foundation for deciphering terpenoid biosynthesis in mealybugs, including the sex pheromone biosynthesis in P. citri.
Keywords: insect pheromones, isoprenyl diphosphate synthase, monoterpenes, phylogenetic analysis
Published in DiRROS: 29.03.2024; Views: 77; Downloads: 33
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2. Qualitative analysis of the minimal Higgins model of glycolysisBrigita Ferčec, Matej Mencinger, Tatjana Petek, Orhan Ozgur Aybar, Ilknur Kusbeyzi Aybar, 2023, original scientific article Abstract: Glycolysis, one of the leading metabolic pathways, involves many
different periodic oscillations emerging at positive steady states of
the biochemical models describing this essential process. One of
the models employing the molecular diffusion of intermediates is
the Higgins biochemical model to explain sustained oscillations. In
this paper, we investigate the center-focus problem for the minimal
Higgins model for general values of the model parameters with the
help of computational algebra. We demonstrate that the model
always has a stable focus point by finding a general form of the first
Lyapunov number. Then, varying two of the model parameters, we
obtain the first three coefficients of the period function for the stable focus point of the model and prove that the singular point is actually a bi-weak monodromic equilibrium point of type $[1, 2]$. Additionally, we prove that there are two (small) intervals for a chosen parameter $a > 0$ for which one critical period bifurcates from this singular point after small perturbations.
Keywords: biological processes, biochemical models, glycolysis
Published in DiRROS: 18.03.2024; Views: 79; Downloads: 41
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3. Discretionary capitalization of development expendituresPrimož Petek, Mateja Jerman, Sandra Janković, 2023, original scientific article Abstract: The paper examines the discretionary nature of (non)capitalizing development expenditures in financial statements. A review of the literature shows that companies may have different motives and factors for (non)capitalizing development expenditures. This study analyzes a sample of 547 companies from the information and communications technology (ICT) sector listed on the Frankfurt Stock Exchange in the period 2009-2018. The ICT sector was selected because it represents an industry with high R&D (research and development) expenditures. The results of the probit regression analysis made on 3,718 observations show that the capitalization of development expenditures is significantly positively related to the size and return on assets of the firm and negatively related to the age of the firm. Larger and more profitable firms are more likely to capitalize development expenditures, while older firms are less likely to capitalize development expenditures. Our results contribute to the literature in the field of positive accounting theory providing additional insights into factors associated with decisions to (non)capitalize development expenditures.
Keywords: capitalization, development expenditures, discretion, incentives, intangible assets
Published in DiRROS: 21.11.2023; Views: 254; Downloads: 149
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4. Rast in kakovost metasekvoje (Metasequoia glyptostroboides Hu et Cheng) v živem arhivu pri LjubljaniIza Petek, Gregor Božič, Dušan Jurc, Kristjan Jarni, Robert Brus, 2022, original scientific article Abstract: Analizirali smo živi arhiv metasekvoje (Metasequoia glyptostroboides Hu et Cheng) na obrečnem rastišču ob Savi pri Ljubljani. Osnovan je bil v letih 1993 in 1994 s sadikami, vzgojenimi iz originalnih semen z območja na Kitajskem, kjer je bila vrsta opisana (klasično nahajališče oz. locus classicus). Drevesa v nasadu so bila prvič izmerjena spomladi leta 2000 in nato še leta 2006, spomladi v letu 2020 pa smo meritve ponovili. V starosti 30 let je povprečno drevo merilo v višino 20,7 m, povprečni premer koreninskega vratu na višini debla 0,1 m je znašal 72,3 cm, povprečni premer debla na prsni višini pa 51,4 cm. Ugotovili smo, da je pogostnost reproduktivnih organov, torej storžev in moških cvetov, povezana s premerom in višino drevesa. Užlebljenost debla je zelo variabilna in povezana s premerom, zelo variabilno je tudi zmanjšanje premera z višino. Povezave med omenjenimi znaki in lego drevesa v nasadu nismo ugotovili. Svetloba oziroma lega v nasadu ni edini dejavnik, ki vpliva na lastnosti posameznega drevesa, vzrok je tudi genetska variabilnost med drevesi.
Keywords: Metasequoia glyptostroboides, semenski nasad, rast, kakovost, Slovenija
Published in DiRROS: 11.08.2022; Views: 680; Downloads: 183
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6. Electrochemical stability and degradation mechanisms of commercial carbon-supported gold nanoparticles in acidic mediaMilutin Smiljanić, Urša Petek, Marjan Bele, Francisco Ruiz-Zepeda, Martin Šala, Primož Jovanovič, Miran Gaberšček, Nejc Hodnik, 2021, original scientific article Published in DiRROS: 22.01.2021; Views: 1628; Downloads: 1120
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7. Synthesis and advanced electrochemical characterization of multifunctional electrocatalytic composite for unitized regenerative fuel cellLeonard Moriau, Marjan Bele, Alen Vižintin, Francisco Ruiz-Zepeda, Urša Petek, Primož Jovanovič, Martin Šala, Miran Gaberšček, Nejc Hodnik, 2019, original scientific article Keywords: electrocatalysis, bifunctional electrocatalysts, oxygen evolution reaction, oxygen reduction reaction, IL-TEM, IL-SEM, EFC-ICP-MS
Published in DiRROS: 24.11.2020; Views: 1428; Downloads: 975
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8. Comparison of Pt-Cu/C with benchmark Pt-Co/C : metal dissolution and their surface interactionsMatija Gatalo, Primož Jovanovič, Urša Petek, Martin Šala, Vid Simon Šelih, Francisco Ruiz-Zepeda, Marjan Bele, Nejc Hodnik, Miran Gaberšček, 2019, original scientific article Keywords: oxygen reduction reaction, proton exchange membrane fuel cell, platinum alloy, metal dissolution, electrochemical flow cell coupled to inductively coupled plasma mass spectrometer
Published in DiRROS: 23.11.2020; Views: 1428; Downloads: 1073
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