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2.
Modelling of dysregulated glucagon secretion in type 2 diabetes by considering mitochondrial alterations in pancreatic ▫$\alpha$▫-cells
Vladimir Grubelnik, Rene Markovič, Saška Lipovšek Delakorda, Gerd Leitinger, Marko Gosak, Jurij Dolenšek, Ismael Valladolid-Acebes, Per-Olof Berggren, Andraž Stožer, Matjaž Perc, Marko Marhl, 2020, izvirni znanstveni članek

Opis: Type 2 diabetes mellitus (T2DM) has been associated with insulin resistance and the failure of β-cells to produce and secrete enough insulin as the disease progresses. However, clinical treatments based solely on insulin secretion and action have had limited success. The focus is therefore shifting towards α-cells, in particular to the dysregulated secretion of glucagon. Our qualitative electron-microscopy-based observations gave an indication that mitochondria in α-cells are altered in Western-diet-induced T2DM. In particular, α-cells extracted from mouse pancreatic tissue showed a lower density of mitochondria, a less expressed matrix and a lower number of cristae. These deformities in mitochondrial ultrastructure imply a decreased efficiency in mitochondrial ATP production, which prompted us to theoretically explore and clarify one of the most challenging problems associated with T2DM, namely the lack of glucagon secretion in hypoglycaemia and its oversecretion at high blood glucose concentrations. To this purpose, we constructed a novel computational model that links α-cell metabolism with their electrical activity and glucagon secretion. Our results show that defective mitochondrial metabolism in α-cells can account for dysregulated glucagon secretion in T2DM, thus improving our understanding of T2DM pathophysiology and indicating possibilities for new clinical treatments.
Ključne besede: diabetes, pancreatic alpha cells, glucagon, mitochondrial dysfunction, free fatty acid
Objavljeno v DKUM: 03.09.2024; Ogledov: 49; Prenosov: 4
.pdf Celotno besedilo (1,60 MB)
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3.
Autolysis affects the iron cargo of ferritins in neurons and glial cells at different rates in the human brain
Sowmya Sunkara, Snježana Radulović, Saška Lipovšek Delakorda, Christoph Birkl, Stefan Eggenreich, Anna Maria Birkl-Toeglhofer, Maximilian Schinagl, Daniel Funk, Michael Stöger-Pollach, Johannes Haybaeck, Walter Gössler, Stefan Ropele, Gerd Leitinger, 2023, izvirni znanstveni članek

Opis: Iron is known to accumulate in neurological disorders, so a careful balance of the iron concentration is essential for healthy brain functioning. An imbalance in iron homeostasis could arise due to the dysfunction of proteins involved in iron homeostasis. Here, we focus on ferritin—the primary iron storage protein of the brain. In this study, we aimed to improve a method to measure ferritin-bound iron in the human post-mortem brain, and to discern its distribution in particular cell types and brain regions. Though it is known that glial cells and neurons differ in their ferritin concentration, the change in the number and distribution of iron-filled ferritin cores between different cell types during autolysis has not been revealed yet. Here, we show the cellular and region-wide distribution of ferritin in the human brain using state-of-the-art analytical electron microscopy. We validated the concentration of iron-filled ferritin cores to the absolute iron concentration measured by quantitative MRI and inductively coupled plasma mass spectrometry. We show that ferritins lose iron from their cores with the progression of autolysis whereas the overall iron concentrations were unaffected. Although the highest concentration of ferritin was found in glial cells, as the total ferritin concentration increased in a patient, ferritin accumulated more in neurons than in glial cells. Summed up, our findings point out the unique behaviour of neurons in storing iron during autolysis and explain the differences between the absolute iron concentrations and iron-filled ferritin in a cell-type-dependent manner in the human brain.
Ključne besede: ferritin, human brain, energy-filtered transmission electron microscopy, quantitative magnetic resonance imaging, autolysis
Objavljeno v DKUM: 20.03.2024; Ogledov: 228; Prenosov: 25
.pdf Celotno besedilo (2,73 MB)
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4.
Vpliv mešanice triphale in ašvagande (Withania somnifera Dunal) na preživetje človeških melanomskih celic in keratinocitov v celični kulturi : magistrsko delo
Tjaša Rifelj, 2024, magistrsko delo

Opis: V magistrski nalogi smo proučevali vpliv mešanice triphale (v nadaljevanju triphale) in ašvagande (Withania somnifera Dunal) na melanomske celice WM 266-4 in keratinocite NHEK. Pripravili smo gojišča za celične kulture melanomskih celic WM 266-4 ter keratinocitov NHEK, ki smo jih izpostavili raztopinam triphale (0,5 %, 1 %, 3 %, 5 %, 6 %, 8 % in 10 % raztopine) in ašvagande (0,25 %, 0,3 %, 0,4 %, 0,5 %, 1 % ter 5 % raztopine). Opravili smo morfološko analizo celic in ugotavljali metabolno aktivnost celic s pomočjo testa WST-8. Ugotovili smo, da triphala ni vplivala na obliko melanomskih celic WM 266-4. Raztopine triphale vseh koncentracij so statistično značilno znižale metabolno aktivnost melanomskih celic WM 266-4 glede na kontrolo. Z višanjem koncentracije raztopine triphale je metabolna aktivnost melanomskih celic WM 266-4 naraščala, vendar v nobenem primeru ni dosegla metabolne aktivnosti melanomskih celic v kontroli. Ašvaganda je v vseh koncentracijah vplivala na vretenasto obliko melanomskih celic WM 266-4, saj so le-te postale okrogle. Statistično značilno je tudi zavirala metabolno aktivnost melanomskih celic WM 266-4 pri vseh koncentracijah. Z višanjem koncentracij raztopine ašvagande se je metabolna aktivnost melanomskih celic WM 266-4 zmanjševala. Prav tako triphala ni vplivala na obliko keratinocitov NHEK. Metabolno aktivnost keratinocitov NHEK je triphala statistično značilno povečala v primerjavi s kontrolo, saj je že 3 % raztopina triphale povečala metabolno aktivnost keratinocitov NHEK za 100 %. Vpliva ašvagande na obliko keratinocitov NHEK in metabolno aktivnost nismo mogli oceniti zaradi tehničnih težav, ki so spremenile pogoje pri eksperimentalnem delu. Ker sta triphala in ašvaganda vplivali na melanomske celice WM 266-4 in keratinocite NHEK, bi bilo smiselno nadaljevati raziskave ter jih razširiti na druge tipe celic.
Ključne besede: ašvaganda, celična kultura, keratinociti, melanomske celice, triphala
Objavljeno v DKUM: 11.03.2024; Ogledov: 327; Prenosov: 17
.pdf Celotno besedilo (4,09 MB)

5.
Starvation hardiness as preadaptation for life in subterranean habitats
Peter Kozel, Tone Novak, Franc Janžekovič, Saška Lipovšek Delakorda, 2023, izvirni znanstveni članek

Opis: Most subterranean habitats, especially caves, are considered extreme environments, mainly because of the limited and erratic food supply and constant darkness. In temperate regions, many climatic conditions, such as temperature and air humidity, are periodically less adverse or even more favourable in caves than the harsh seasonal weather on the surface. Accordingly, many animal species search for hibernacula in caves. These overwintering, non-specialized subterranean species (nontroglobionts) show various modes of dormancy and ongoing development. Since they do not feed, they all undergo periodic starvation, a preadaptation, which might evolve in permanent starvation hardiness, such as found in most specialized subterranean species (troglobionts). To this end, we performed a comparative analysis of energy-supplying compounds in eleven most common terrestrial non-troglobiont species during winter in central European caves. We found highly heterogeneous responses to starvation, which are rather consistent with the degree of energetic adaptation to the habitat than to overwintering mode. The consumption of energy-supplying compounds was strongly higher taxa-dependant; glycogen is the main energy store in gastropods, lipids in insects, and arachnids rely on both reserve compounds. We assume that permanent starvation hardiness in specialized subterranean species might evolved in many different ways as shown in this study.
Ključne besede: subterranean habitats, caves, starvation hardiness
Objavljeno v DKUM: 08.12.2023; Ogledov: 449; Prenosov: 40
.pdf Celotno besedilo (6,56 MB)
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6.
Vpliv nima (azadirachta indica a. juss) in triphale mešanice na preživetje človeških melanomskih celic in keratinocitov v celični kulturi : magistrsko delo
Ana Marija Hirtl, 2023, magistrsko delo

Opis: Nim in triphala mešanica (v nadaljevanju triphala) sta v ajurvedski medicini uporabljeni za lajšanje različnih bolezenskih stanj. V magistrski nalogi smo želeli raziskati vpliv nima in triphale na obliko in metabolno aktivnost melanomskih celic WM 266-4 in keratinocitov NHEK. S tem namenom smo pripravili gojišči za celični kulturi melanomskih celic WM 266-4 in keratinocitov NHEK, gojili celice in analizirali vplive raztopin nima in triphale na opazovane celice. Pri eksperimentalnem delu smo uporabili metodi svetlobne mikroskopije in spektrofotometrije. S slednjo smo analizirali rezultate testa WST8, ki je metoda za določitev metabolne aktivnosti. Ugotovili smo, da nim vpliva na obliko melanomskih celic WM 266-4 in zmanjša njihovo metabolno aktivnost. Nim ni vplival na obliko in metabolno aktivnost keratinocitov NHEK. Triphala ni vplivala na obliko melanomskih celic WM 266-4; nizke koncentracije triphale so njihovo metabolno aktivnost zmanjšale, najvišja koncentracija jo je povečala. Triphala ni vplivala na obliko keratinocitov NHEK; njihova metabolna aktivnost se je povečala pri vseh koncentracijah triphale. Raztopine nima in triphale skupaj so povzročile spremembo oblike melanomskih celic WM 266-4 in zmanjšale njihovo metabolno aktivnost. Raztopine nima in triphale skupaj so vplivale na obliko nekaterih keratinocitov NHEK. Metabolna aktivnost keratinocitov NHEK je bila povečana pri najvišji koncentraciji nima in triphale; nižje koncentracije nima in triphale niso vplivale na njihovo metabolno aktivnost. Ker so vse raztopine nima vplivale na obliko melanomskih celic WM 266-4 in zmanjšale njihovo metabolno aktivnost, bi bilo smiselno nadaljevati z raziskavami njegovih učinkov na različne tipe celic.
Ključne besede: nim, triphala, melanom, melanomske celice in keratinociti
Objavljeno v DKUM: 05.10.2023; Ogledov: 526; Prenosov: 68
.pdf Celotno besedilo (3,18 MB)

7.
Duality of terrestrial subterranean fauna
Tone Novak, Matjaž Perc, Saška Lipovšek Delakorda, Franc Janžekovič, 2012, izvirni znanstveni članek

Opis: Terrestrial animals in subterranean habitats are often classified according to their degree of morphological or ecological specialization to the subterranean environment. The commonly held view is that, as distance into a cave increases, the frequency of morphologically specialized, i.e., troglomorphic, species or ecological specialization will increase. We tested this hypothesis for the fauna in 54 caves in Slovenia-the classical land for subterranean biology. We found that there exist two ecologically well separated terrestrial subsurface faunas: one shallow and one deep. 1) The shallow subterranean fauna, adapted to the terrestrial shallow subterranean habitats (SSHs) in the upper 10 m of subsurface strata, is most diverse. It consists of randomly distributed non-troglobionts and a major group of troglobionts adapted to the soil root zone. 2) The deep subterranean fauna is represented by a minor group of troglobionts, adapted to caves. Troglobionts are strictly divided between the two faunas. There is strong evidence that in karstic ecosystems with deep-rooted vegetation this might be a global pattern, or that in these locations only the shallow subterranean fauna exist.
Ključne besede: endemites, superficial subterranean habitats, trogloxenes, troglophiles, troglobionts
Objavljeno v DKUM: 04.08.2017; Ogledov: 1459; Prenosov: 500
.pdf Celotno besedilo (1,94 MB)
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8.
Cold tolerance in terrestrial invertebrates inhabiting subterranean habitats
Tone Novak, Nina Šajna, Estera Antolinc, Saška Lipovšek Delakorda, Dušan Devetak, Franc Janžekovič, 2014, izvirni znanstveni članek

Opis: Most organisms are able to survive shorter or longer exposure to sub-zero temperatures. Hypothetically, trogloxenes characterized as not adapted, and troglophiles as not completely adapted to thermally stable subterranean environment, have retained or partially retained their ability to withstand freezing, while most troglobionts have not. We tested this hypothesis experimentally on 37 species inhabiting caves in Slovenia, analyzing their lower lethal temperatures in summer and winter, or for one season, if the species was not present in caves during both seasons. Specimens were exposed for 12 hrs to 1°C-stepwise descending temperatures with 48 hr breaks. In general, the resistance to freezing was in agreement with the hypothesis, decreasing from trogloxenes over troglophiles to troglobionts. However, weak resistance was preserved in nearly all troglobionts, which responded in two ways. One group, withstanding freezing to a limited degree, and increasing freezing tolerance in winter, belong to the troglobionts inhabiting the superficial subterranean habitats. The other group, which equally withstand freezing in summer and winter, inhabit deep subterranean or other thermally buffered subterranean habitats. Data on cold resistance can thus serve as an efficient additional measure of adaptation to particular hypogean environments.
Ključne besede: endemites, superficial subterranean habitats, trogloxenes, troglophiles, troglobionts
Objavljeno v DKUM: 04.08.2017; Ogledov: 1480; Prenosov: 376
.pdf Celotno besedilo (358,59 KB)
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9.
Remarks on Neuroptera of the North-eastern part of Slovenia (Goričko)
Saška Lipovšek Delakorda, Bojana Mencinger Vračko, 2002, objavljeni znanstveni prispevek na konferenci

Opis: The abundance of spedies of Neuroptera was studied in the traditional cultural landscape of Goričko (NE Slovenia). The insects were collected during 1997-1998 and 1999 at 12 different localities. The green lacewing Chrysoperla carnea sensu lato was the most dominant species in the region. This species was the only one found in cultivated fields in Goričko district
Ključne besede: zoology, Neuroptera, net-winged insects, Goričko, Slovenia
Objavljeno v DKUM: 03.08.2017; Ogledov: 1571; Prenosov: 97
.pdf Celotno besedilo (324,55 KB)
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10.
Malpighian tubule cells in overwintering cave crickets Troglophilus cavicola (Kollar, 1833) and T. neglectus Krauss, 1879 (Rhaphidophoridae, Ensifera)
Saška Lipovšek Delakorda, Tone Novak, Franc Janžekovič, Nina Weiland, Gerd Leitinger, 2016, izvirni znanstveni članek

Opis: During winter, cave cricket larvae undergo dormancy in subterranean habitats; this dormancy is termed diapause in second year Troglophilus cavicola larvae because they mature during this time, and termed quiescence in T. neglectus, because they mature after dormancy. Here we used electron microscopy to analyze ultrastructural changes in the epithelial cells in the Malpighian tubules (MTs) of T. cavicola during diapause, in order to compare them with previous findings on T. neglectus. Moreover, the autophagosomes were studied with immunofluorescence microscopy in both species. Although the basic ultrastructure of the cells was similar, specific differences appeared during overwintering. During this natural starvation period, the nucleus, rER, the Golgi apparatus and mitochondria did not show structural changes, and the spherites were exploited. The abundances of autophagic structures in both species increased during overwintering. At the beginning of overwintering, in both species and sexes, the rates of cells with autophagic structures (phagophores, autophagosomes, autolysosomes and residual bodies) were low, while their rates increased gradually towards the end of overwintering. Between sexes, in T. cavicola significant differences were found in the autophagosome abundances in the middle and at the end, and in T. neglectus at the end of overwintering. Females showed higher rates of autophagic cells than males, and these were more abundant in T. cavicola. Thus, autophagic processes in the MT epithelial cells induced by starvation are mostly parallel in diapausing T. cavicola and quiescent T. neglectus, but more intensive in diapausing females.
Ključne besede: cave cricket, overwintering, Troglophilus cavicola, Troglophilus neglectus
Objavljeno v DKUM: 19.06.2017; Ogledov: 1396; Prenosov: 387
.pdf Celotno besedilo (9,29 MB)
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