Phylogeographic study of brown trout from Serbia, based on mitochondrial DNA control region analysis

In order to illuminate the phylogeography of brown trout (Salmo trutta) populations in the Balkan state of Serbia, the 561 bp 5'-end of mtDNA control region of 101 individuals originating from upland tributaries of the Danubian, Aegean and Adriatic drainages were sequenced and compared to corresponding brown trout sequences obtained in previous studies. Among 15 haplotypes found, 14 were considered native, representing the Danubian and Adriatic lineages of the brown trout, while one haplotype (ATcs1), found only in two individuals originating from two stocked rivers, corresponded to the Atlantic lineage and was considered introduced. Native haplotypes exhibited a strong geographic pattern of distribution: the Danubian haplotypes were strictly confined to the Danubian drainage, while the Adriatic haplotypes dominated in the Aegean and Adriatic drainages; most of the total molecular variance (69%) was attributed to differences among the drainages. Phylogenetic reconstruction, supplemented with seven haplotypes newly described in this study, suggested a sister position of the Atlantic-Danubian and Adriatic-Mediterranean-marmoratus ("southern") phylogenetic group, and pointed to the existence of a distinct clade, detected within the "southern" group. The data obtained confirmed our expectation of the existence of high genetic diversity in Balkan trout populations, and we recommend more widespread surveys covering trout stocks from the region

Transferrin gene expression in Salmo sp.

Salmonidae family combines freshwater and anadromous fish species. Duplicates of numerous genomic DNA loci are characteristic for this family, some as a consequence of tetraploidisation, and others as independent doubling of discrete DNA regions. In the genus Salmo, duplication of transferrin gene in Atlantic salmon, brown and marble trout has been demonstrated. The aim of the study was to characterize the promoter region of both genes (TF1 and TF2) in all three species and to determine the ratio of expression of TF1 and TF2 in Atlantic salmon. Applying qPCR we showed that TF2 is expressed in Atlantic salmon six times weaker than TF1. It has been previously shown that the difference in the expression of both genes in brown and marble trout is even higher. The nucleotide sequence was determined for promoter regions of both genes in all species. In promoter region, microsatellite was found, which differs in length as well within species as between TF1 and TF2 locus, and four SNPs that differentiate TF1 and TF2. For Atlantic salmon, longer sequence of promoter region was determined. In TF1 gene, promoter contains a minisatellite, comprised of 37 bp long motif with over 20 replicates, while in TF2 minisatellite is not present. Analyzing potential binding sites in promoter region, functional elements for regulation of transferrin gene expression were found

How Can We Advance Integrative Biology Research in Animal Science in 21st Century?:Experience at University of Ljubljana from 2002 to 2022

In this perspective analysis, we strive to answer the following question: how can we advance integrative biology research in the 21st century with lessons from animal science? At the University of Ljubljana, Biotechnical Faculty, Department of Animal Science, we share here our three lessons learned in the two decades from 2002 to 2022 that we believe could inform integrative biology, systems science, and animal science scholarship in other countries and geographies. Cultivating multiomics knowledge through a conceptual lens of integrative biology is crucial for life sciences research that can stand the test of diverse biological, clinical, and ecological contexts. Moreover, in an era of the current COVID-19 pandemic, animal nutrition and animal science, and the study of their interactions with human health (and vice versa) through integrative biology approaches hold enormous prospects and significance for systems medicine and ecosystem health

Attitudes of students of different age regarding factores of academic achievement

The thesis presents the attitudes of the students of the 5th, 7th and 9th grade regarding particular factors of academic achievement. The theoretical part deals with the basic characteristics of academic achievement, the factors of academic achievement and the attitudes that refer to the factors of academic achievement. Three groups of factors of academic achievement are primarily described in detail: personal characteristics, characteristics of the family and those of the school environment, which are all discussed in detail through the students’ attitudes in the thesis research. The empirical part of the thesis presents research results, those of the 516 students of the 5th, 7th and 9th grade of eight different elementary schools. The research contained individual questions from the questionnaire developed by dr. Helena Smrtnik Vitulić and dr. Irena Lesar. The interests of the thesis research were: 1) what the attitudes of the students of the 5th, 7th and 9th grade were on the intellectual and speech abilities, personal traits, strictness of teachers and knowledge of students, as well as the level of education and financial status of the family as factors of academic achievement; and 2) if students of different grades significantly differentiate in the understanding of the meaning of limited factors of academic achievement. The results show that the students believe that their academic evaluation sometimes depends on the individual’s speech and intellectual abilities; significant differences between the students of the 5th, 7th and 9th grade mainly showed in their speech abilities, not so much in their intellectual abilities. Students of different grades have recognized studiousness out of several extended personal characteristics as the most important trait of an individual’s academic achievement. It is followed by acceptance, openness, emotional stability, and lastly extroversion; there were considerable differences between the students of the 5th, 7th and 9th grade and their understanding of the meaning of some personal traits (acceptance, openness and emotional stability). Students of different grades have partly agreed on academic evaluation being dependent on a teacher’s strictness and on a student’s level of knowledge. The students of the 9th grade were considerably more convinced than those of the 7th and 5th grade, that the teacher’s strictness during the academic evaluation influences the individual’s academic achievement. The students of the 5th grade were noticeably more convinced than those of the 7th and 9th grade, that teachers only evaluate the knowledge of the students. Students of different grades have answered that it mostly isn’t valid, that the level of education and the financial status of the parents influence the student’s academic achievement; the students of the 5th grade were considerably more convinced than those of the 7th and 9th grade, that the education level of the parents influences the academic achievement; as far as the attitudes on the financial status of the parents are concerned, there were no distinctions between the students of different grades

Laser capture microdissection of pigment cells from Salmonid fish skin to identify differentially expressed genes in an enriched cell population

In order to determine the function of pigment cell types in different pigment pattern of skin, we have applied the laser capture microdissection method (LCM) for isolation of different pigment cell types from skin sections of marble trout (Salmo marmoratus) and brown trout (S. trutta), characterized with labyrinthine and spotted skin pattern, respectively. RNA was isolated from dissected pigment cell populations and used for expression analysis. Expression profiles of candidate genes, potentially involved in pigmentation, in LCM isolated pigment cell population, were more specific compared to differently pigmented skin regions, containing a heterogeneous mixture of cells, including more types of chromatophores. Moreover, they could provide important information about particular pigment cell type function and its contribution to different pigment pattern. Protocol of combined LCM and genomic approach to study single pigment cell populations can be applied in the future, but needs to be further optimized in order to yield RNA of sufficient quantity and quality required for i.e. transcriptomic analyses

Morphological differences in the skin of marble trout Salmo marmoratus and brown trout Salmo trutta

Despite being genetically very closerly related, the marble trout Salmo marmoratus and the brown trout Salmo trutta exibit marked phenotypic differences, particularly with regard to skin pigmentation. Histological analysis of skin from the head and gill cover of differently aged individuals of the two species was carried out in order to characterize differences in skin structure. The basic structure of skin of the individuals studied corresponded with that described for other salmonids, though the head epidermis was somewhat thicker in S. marmoratus than in S. trutta, thickening with age in both species. Numerous secretory goblet cells and sporadic secretory sacciform cells were observed in the upper and middle part of the epidermis in both species. Melanophores were present in both species only in the dermis, and were bigger in S. marmoratus and present at lower average density than in S. trutta, and more or less constant across all age classes. In adult S. marmoratus with fully established marble pigmentation, light areas at low density with small (i.e. aggregated) melanophores were present, while in S. trutta melanophores were more uniformly distributed

Isolation of chromatophores from brown trout (Salmo trutta) skin

As new techniques for single-cell analysis are evolving, there is a growing need for streamlined and flexible protocols for single-cell suspension preparation and single-cell isolation. Based on previous research on the model species zebrafish (Danio rerio), a novel protocol for the isolation of chromatophores from brown trout (Salmo trutta) skin was developed and specific gene expression in chromatophore types evaluated with qPCR. This is the first report on a protocol for the isolation of chromatophores from the skin of salmonids. The method is simple and fast (taking about 90 min), requires no special equipment and is in line with the high ethical standards required in animal research, as no animals need to be sacrificed. In addition, skin biopsies can be taken from the same fish at multiple time points, allowing monitoring of chromatophore differentiation and their involvement in the formation of pigmentation patterns. The protocol should be effective for the vast majority of salmonid species due to similarities in skin morphology

Reproduction parameters of hatchery reared grayling (Thymallus thymallus) females

European grayling (Thymallus thymallus) is an endangered salmonid fish species and its populations have decreased considerably in European waters in recent decades. One of the conservation measures applied to grayling is stocking with hatchery-reared fish. To advance the knowledge of grayling reproduction in the hatchery, husbandry data were systematically collected in the period from 2006 to 2015 during grayling spawning seasons and analyzed to quantify grayling female reproductive parameters such as fecundity, egg size, and embryo survival to the eyed egg stage. Data was collected for first time spawners (3 years old) and repeat spawners reared in the hatchery. Statistically significant differences were found for the number of eggs between first time spawners, producing on average 3600 eggs, and repeat spawners, producing on average 8000 eggs. Absolute fecundity was positively correlated to grayling female total length and weight for both first time and repeat spawners. However, relative fecundity did not correlate with these parameters. A positive correlation was observed between female total length and mean egg weight for repeat spawners, while the correlation was negative for first time spawners. Heavier eggs tended to have a higher rate of survival until the eyed egg stage, though the correlation was stronger for first time spawners than for repeat spawners. Due to the higher reproductive success of repeat spawners, it could be concluded that larger and older grayling females should be included in hatchery reproduction