1. Observations on the surface structure of Aurelia solida (Scyphozoa) polyps and medusaeValentina Turk, Ana Fortič, Maja Kos Kramar, Magda Tušek-Žnidarič, Jasna Štrus, Rok Kostanjšek, Alenka Malej, 2021, original scientific article Abstract: The surface structures and mucus layers that form an interface between the epithelial layer of organisms and their external environment were studied in the bloom-forming moon jellyfish (Aurelia solida, Scyphozoa) from the northern Adriatic. The surface of the polyps revealed epithelial ciliated cells and numerous nematocysts, both non-discharged and discharged. Cilia were also the most prominent features on the surface of adult medusa, protruding from the epidermal cells and with microvilli surrounding the base. Histochemical methods and various microscopy techniques (light/epifluorescence and electron microscopy) confirmed the presence of abundant mucus around polyps and on the surfaces of adult medusa, and that the mucus contained acidic and neutral mucins. The observed mucus secretions on the exumbrella surface of the medusae were in the form of granules, flocs, and sheets. Scanning electron microscopy and transmission electron microscopy analyses confirmed the presence of various microbes in the mucus samples, but not on the epithelial surfaces of the polyps or the exumbrella of the medusae.
Published in DiRROS: 19.07.2024; Views: 131; Downloads: 106
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2. A small bacteriophage protein determines the hierarchy over co-residential jumbo phage in Bacillus thuringiensis serovar israelensisAnja Pavlin, Anže Lovše, Gregor Bajc, Jan Otoničar, Amela Kujović, Živa Lengar, Ion Gutiérrez-Aguirre, Rok Kostanjšek, Janez Konc, Nadine Fornelos, Matej Butala, 2022, original scientific article Abstract: Bacillus thuringiensis serovar israelensis is the most widely used biopesticide against insects, including vectors of animal and human diseases. Among several extrachromosomal elements, this endospore-forming entomopathogen harbors two bacteriophages: a linear DNA replicon named GIL01 that does not integrate into the chromosome during lysogeny and a circular-jumbo prophage known as pBtic235. Here, we show that GIL01 hinders the induction of cohabiting prophage pBtic235. The GIL01-encoded small protein, gp7, which interacts with the host LexA repressor, is a global transcription regulator and represses the induction of pBtic235 after DNA damage to presumably allow GIL01 to multiply first. In a complex with host LexA in stressed cells, gp7 down-regulates the expression of more than 250 host and pBtic235 genes, many of which are involved in the cellular functions of genome maintenance, cell-wall transport, and membrane and protein stability. We show that gp7 homologs that are found exclusively in bacteriophages act in a similar fashion to enhance LexA’s binding to DNA, while likely also affecting host gene expression. Our results provide evidence that GIL01 influences both its host and its co-resident bacteriophage.
Published in DiRROS: 18.07.2024; Views: 111; Downloads: 104
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3. A new obligate groundwater species of Asellus (Isopoda, Asellidae) from IranMohammad Javad Malek-Hosseini, Jure Jugovic, Yaser Fatemi, Matjaž Kuntner, Rok Kostanjšek, Christophe J. Douady, Florian Malard, 2022, original scientific article Abstract: With only 43 described stygobionts and only two isopod species the obligate groundwater fauna of Iran, a vast country with over 10% of limestone surface, is inadequately known. Here, we report the discovery of Asellus ismailsezarii sp. nov. from Zagros mountains, the first eyeless and depigmented asellid isopod from Iran. The new species is morphologically similar to Asellus monticola Birstein, 1932, but it is eyeless and fully depigmented, has a slightly curved pereopod IV and does not bear any setae on proximal margins of exopodite of pleopods IV and V. Species phylogenetic relationships using original and datamined mitochondrial DNA and nuclear rDNA, and estimation of molecular divergences with other Asellus species, suggest that A. ismailsezarii sp. nov. is sister to a larger clade that also contains the European A. aquaticus species complex. Surface populations of Asellus have colonized groundwater at multiple occasions and localities, both in Europe and Asia, giving rise to species and subspecies that have evolved troglomorphisms, such as depigmentation and loss of eyes. Of the 37 formally described species and subspecies of Asellus, 15 are from groundwater, including A. ismailsezarii sp. nov. We predict that many more obligate groundwater Asellus taxa are yet to be discovered in Asia.
Keywords: Asia, groundwater, molecular phylogeny, taxonomy, troglomorphy
Published in DiRROS: 16.07.2024; Views: 137; Downloads: 107
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