1071. Evaluation of cyanobacteria biomass derived from upgrade of phycocyanin fluorescence estimationTinkara Rozina, Bojan Sedmak, Maja Zupančič Justin, Andrej Meglič, 2017, original scientific article Abstract: The number of harmful cyanobacterial blooms has increased significantly at the global level in recent years. One of the characteristics of cyanobacteria that gives them advantage over other phytoplankton organisms are auxiliary photosynthetic pigments, such as phycocyanin. This fluorescent pigment emits light at a different wavelength as chlorophyll and can therefore be used for detection of cyanobacteria in situ. In this study we used submersible phycocyanin fluorescence sensors and compare their voltage output to concentration of extracted phycocyanin, cell counts and biovolume. The relation was linear in all three cases; however, the variability of regression line slopes between different cyanobacteria strains was high in the case of PC extract concentration and cell count. The highest uniformity in the linear fits was between fluorescence signal and biovolume therefore making it the best candidate for fluorescence sensor voltage output conversion. In the context of this work we also compared different methods for PC extraction. Modifying the equations by subtracting the absorption at 750 nm almost entirely reduces the false PC concentration estimation due to sample turbidity.
Keywords: fluorescence measurements, phycocyanin, cyanobacteria
Published in DiRROS: 01.08.2024; Views: 392; Downloads: 164
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1072. Coralline algae on biogenic formations in marine waters off Slovenia (northern Adriatic Sea)Martina Orlando-Bonaca, Borut Mavrič, Lovrenc Lipej, Sara Kaleb, Annalisa Falace, 2017, original scientific article Abstract: Two major biogenic formations, composed mainly by dead corallites of the Mediterranean stony coral (Cladocora caespitosa), have been recently studied in Slovenian marine waters. The paper presents new data about the presence of coralline algae on the biogenic formation situated off Cape Ronek and off Cape Debeli rtič. Coralline algae are very important for the creation, development and maintenance of calcareous bio-concretions that offer new niches for many invertebrates and other algae. They are listed as important builders of the coralligenous biocoenosis in the "Draft Lists of coralligenous/maërl populations and of main species to be considered by the inventory and monitoring" of the RAC-SPA, and should be further deeply studied and appropriately protected.
Keywords: coralline algae, biogenic formations, circalittoral, northern Adriatic, Slovenia
Published in DiRROS: 01.08.2024; Views: 354; Downloads: 314
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1073. Unusual bloom of tetrasporophytes of the non-indigenous red alga Asparagopsis armata in the northern Adriatic SeaMartina Orlando-Bonaca, Borut Mavrič, Domen Trkov, Lovrenc Lipej, 2017, original scientific article Abstract: The tetrasporophyte of the non-indigenous red alga Asparagopsis armata (the Falkenbergia stage) is considered to be established in Slovenian coastal waters. However, until 2016, it was found only in low coverage and in few localities with hard substrata. The paper reports a recent bloom of these tetrasporophytes in the mediolittoral belt of the Bay of Piran, where thalli of this red alga overgrew the articularted coralline alga Corallina officinalis. The sites affected by this large expansion of tetrasporophytes of A. armata should be regularly monitored in the future, in order to point out which environmental factors are responsible for such phenomenon, and to formulate proper conclusions on the status of this non-indigenous alga in the coastal area concerned.
Keywords: non-indigenous species, coastal waters, autburst, northern Adriatic Sea
Published in DiRROS: 01.08.2024; Views: 374; Downloads: 228
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1074. Combined use of chlorophyll a and phycocyanin fluorescence sensors for quantification and differentiation of phytoplankton : a useful approach for small surface water bodiesTinkara Rozina, Tina Eleršek, Maja Zupančič Justin, Andrej Meglič, 2018, original scientific article Abstract: Sensors based on in vivo measurements of photosynthetic pigments fluorescence enable real-time phytoplankton monitoring with high spatial and temporal resolution. A combination of chlorophyll a (CHL) and phycocyanin (PC) fluorescence sensors was used for phytoplankton quantification and differentiation in two small water bodies, Koseze Pond and pond in Hotinja vas. The high correlation of CHL and PC fluorescence signals with biovolume was confirmed during the two-year monitoring in anatural pond environment in spite of a seasonal succession of the phytoplankton. Additionally, disturbances of the sensors were investigated. Water bodies containing predominantly algae yielded false positive signals of the PC sensor, which reached up to 1% of the intensity of the CHL signal. Similarly, underestimated counts of cyanobacteria measured with CHL fluorescence sensor can be adjusted using PC fluorescence sensor.
Keywords: small water bodies, algae, cyanobacteria, fluorescence sensors, biovolume
Published in DiRROS: 01.08.2024; Views: 334; Downloads: 217
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1075. Stress tolerance of three opportunistic black yeastsJanja Zajc, Cene Gostinčar, Metka Lenassi, Nina Gunde-Cimerman, 2018, original scientific article Abstract: Many species of black yeasts can survive extremely harsh conditions and can quickly adapt to novel environments. These traits were proposed to have a role in the ability of some fungal species tocolonise indoor habitats inhospitable for majority of microorganisms, and to cause (opportunistic)infections in humans. In order to better understand the stress tolerance of black yeasts and thereby their opportunism, we focused our research on the three model black yeasts: the polyextremotolerant Au-reobasidium melanogenum and Exophiala dermatitidis, and the extremely halotolerant Hortaeawerneckii. These black yeasts are shown to thrive at temperatures, salinities, pH values and, H2O2 concentrations that inhibit growth of mesophilic species. Most importantly, unlike their close relatives they can not only grow, but also synthesize siderophores (E. dermatitidis) or degradeproteins (A. melanogenum) at 37 °C - traits that are crucial for pathogenesis in humans. These results support the hypothesis that the ability to cope with various environmental stresses is linked to the opportunistic behaviour of fungi. Therefore, better understanding of the connections between the stress-tolerant biology of black fungi and their ability to cause disease is needed, in particular due to their changing interactions with humans and their emerging pathogenicity.
Keywords: melanised fungi, temperature, NaCl, pH tolerance, ROS, oligotrophism, proteolytic activity, capsule
Published in DiRROS: 01.08.2024; Views: 376; Downloads: 205
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1076. "Only introduced" or "invasive" : spread of the alga Aulacoseira ambigua f. japonica from Asia to Africa and EuropeTina Eleršek, 2018, original scientific article Abstract: Many non-native algal species are found in waters all over the world. Many terms are used to describe such organisms that have expanded their distribution. However, a unified model or concept remains to be defined, as how biological ‘invasions’ are seen depends on the perspective. Understanding invasive organisms is important for biodiversity, science policy and water management. During monitoring sampling at Slivniško Lake (Slovenia) in 2016, the curved diatom Aulacoseira ambigua f. japonica Tuji & D.M. Williams was identified. This species originates from Japan, from where it was described more than 100 years ago. The chronology of the published distributions of A. ambigua f. japonica defines its spread from Japan to Asia, then to western Russia and South Africa, and now to central Europe. This study provides further evidence that A. ambigua f. japonica has become established in Europe (Slovenia), as supported by light microscopy and scanning electron microscopy. To the best of our knowledge, this is the first qualitative and quantitative description of A. ambigua f. japonica in Europe. It has been suggested that the shape of these algal colonies is significant for the interpretation of ecological information, and indeed, also in the present case, spiral colonies were found in this eutrophic water body. Although curved cells and colonies can also be interpreted as (sub)populations or morphological variants, only detailed molecular studies can reveal if these also have taxonomic significance.
Keywords: algae, introduced species, invasive species, scanning electron microscopy
Published in DiRROS: 01.08.2024; Views: 446; Downloads: 268
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1077. First record of the nudibranch Marionia blainvillea (Risso, 1818) (Gastropoda: Heterobranchia) for MontenegroVesna Mačić, Milica Jovanović, Domen Trkov, Lovrenc Lipej, 2018, original scientific article Abstract: One specimen belonging to the nudibranch Marionia blainvillea (Risso, 1818) was found crawling on the gorgonian Leptogorgia sarmentosa (Esper, 1789) at Sv. Nedjelja, Boka Kotorska Bay, Montenegro. This is the first record of the species for Montenegrin waters and the third for the Adriatic Sea.
Keywords: seaslug, coralligenous assemblage, Boka Kotorska, Montenegro
Published in DiRROS: 01.08.2024; Views: 362; Downloads: 205
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1078. Network modelling unravels mechanisms of crosstalk between ethylene and salicylate signalling in potatoŽiva Ramšak, Anna Coll Rius, Tjaša Stare, Oren Tzfadia, Špela Baebler, Yves Van de Peer, Kristina Gruden, 2018, original scientific article Abstract: To develop novel crop breeding strategies, it is crucial to understand the mechanisms underlying the interaction between plants and their pathogens. Network modeling represents a powerful tool that can unravel properties of complex biological systems. In this study, we aimed to use network modeling to better understand immune signaling in potato (Solanum tuberosum). For this, we first built on a reliable Arabidopsis (Arabidopsis thaliana) immune signaling model, extending it with the information from diverse publicly available resources. Next, we translated the resulting prior knowledge network (20,012 nodes and 70,091 connections) to potato and superimposed it with an ensemble network inferred from time-resolved transcriptomics data for potato. We used different network modeling approaches to generate specific hypotheses of potato immune signaling mechanisms. An interesting finding was the identification of a string of molecular events illuminating the ethylene pathway modulation of the salicylic acid pathway through Nonexpressor of PR Genes1 gene expression. Functional validations confirmed this modulation, thus supporting the potential of our integrative network modeling approach for unraveling molecular mechanisms in complex systems. In addition, this approach can ultimately result in improved breeding strategies for potato and other sensitive crops.
Keywords: network modelling, potato, molecular biology
Published in DiRROS: 01.08.2024; Views: 343; Downloads: 268
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1079. First record of the meagre, Argyrosomus regius (Asso, 1801), in Slovenian coastal waters with additional records from the Croatian part of the Adriatic SeaBorut Mavrič, Branko Dragičević, 2018, original scientific article Abstract: One specimen of meagre, Argyrosomus regius (Asso, 1801), was caught by trawling in the waters off Slovenia on 24th November 2016 at the depth of cca. 20 m above sandy-muddy bottom. This is the fi rst record of this species for the Slovenian part of the Adriatic Sea. Due to the fact that there are no wild populations in the Middle and North Adriatic and that remaining wild populations in the Southern Adriatic are scarce and small, the specimen is supposed to be an escapee from one of the mariculture facilities. Additional occurrences of this species from the Croatian part of the Adriatic Sea are reported.
Keywords: meagre, farm escapee, Adriatic Sea, aquaculture
Published in DiRROS: 01.08.2024; Views: 347; Downloads: 211
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1080. A new genus and two new species of cave-dwelling cyclopoids (Crustacea, Copepoda) from the epikarst zone of Thailand and up-to-date keys to genera and subgenera of the Bryocyclops and Microcyclops groupsChaichat Boonyanusith, La-orsri Sanoamuang, Anton Brancelj, 2018, original scientific article Abstract: Two obligate cave-dwelling species of cyclopoid copepods (Copepoda, Cyclopoida) were discovered inside caves in central Thailand. Siamcyclops cavernicolus gen. et sp. nov. was recognised as a member of a new genus. It resembles Bryocyclops jankowskajae Monchenko, 1972 from Uzbekistan (part of the former USSR). It differs from it by (1) lack of pointed triangular prominences on the intercoxal sclerite of the fourth swimming leg, (2) mandibular palp with three setae, (3) spine and setal formulae of swimming legs 3.3.3.2 and 5.5.5.5, respectively, and (4) specific shape of spermatophore. Metacyclops thailandicus sp. nov. resembles M. cushae Reid, 1991 from Louisiana (USA). It differs from it by (1) distal segment of the endopod of the fourth swimming leg with one apical spine, (2) the fifth swimming legs with one broad segment, (3) the spine formula of the distal segment of the exopod of the swimming legs 3.4.3.3, and (4) well developed anal operculum reaching articulation with caudal rami. Detailed descriptions of the habitats of the new species and up-to-date keys to the genera and subgenera of the Bryocyclops and Microcyclops groups are provided, along with an updated list of obligate groundwater species of Copepoda in Southeast Asia.
Keywords: Siamcyclops cavernicolus gen. et sp. nov., Metacyclops thailandicus sp. nov., stygobionts, groundwater environment, epikarstic drip
Published in DiRROS: 01.08.2024; Views: 323; Downloads: 316
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