RNA Pol II Promotes Transcription of Centromeric Satellite DNA in Beetles

Transcripts of centromeric satellite DNAs are known to play a role in heterochromatin formation as well as in establishment of the kinetochore. However, little is known about basic mechanisms of satellite DNA expression within constitutive heterochromatin and its regulation. Here we present comprehensive analysis of transcription of abundant centromeric satellite DNA, PRAT from beetle Palorus ratzeburgii (Coleoptera). This satellite is characterized by preservation and extreme sequence conservation among evolutionarily distant insect species. PRAT is expressed in all three developmental stages: larvae, pupae and adults at similar level. Transcripts are abundant comprising 0.033% of total RNA and are heterogeneous in size ranging from 0.5 kb up to more than 5 kb. Transcription proceeds from both strands but with 10 fold different expression intensity and transcripts are not processed into siRNAs. Most of the transcripts (80%) are not polyadenylated and remain in the nucleus while a small portion is exported to the cytoplasm. Multiple, irregularly distributed transcription initiation sites as well as termination sites have been mapped within the PRAT sequence using primer extension and RLM-RACE. The presence of cap structure as well as poly(A) tails in a portion of the transcripts indicate RNA polymerase II–dependent transcription and a putative polymerase II promoter site overlaps the most conserved part of the PRAT sequence. The treatment of larvae with alpha-amanitin decreases the level of PRAT transcripts at concentrations that selectively inhibit pol II activity. In conclusion, stable, RNA polymerase II dependant transcripts of abundant centromeric satellite DNA, not regulated by RNAi, have been identified and characterized. This study offers a basic understanding of expression of highly abundant heterochromatic DNA which in beetle species constitutes up to 50% of the genome

Prvi nalaz vrste Eualus drachi Noël, 1978 (Decapoda: Caridea) u Jadranskom moru

Three specimens of decapod shrimp Eualus drachi Noël, 1978, were found in the red coral rem-nant collected for commercial purposes near the island Sveti Andrija, Croatia. It is the first record of this species in the Adriatic Sea. The decapod biodiversity of deeper coralligenous habitats, such as the red coral colonies, is poorly investigated in contrast to coastal areas and soft bottoms of traditional trawling grounds. This paper highlights the usefulness of examining the remnants of a commercial coral extraction originating from previously less investigated marine habitats in order to improve the knowledge on the biodiversity of such habitats.Tri primjerka kozice Eualus drachi Noël, 1978, pronađena su u ostatku crvenog koralja prikupljenom u komercijalne svrhe u blizini otoka Sveti Andrija, Hrvatska. To je prvi nalaz ove vrste u Jadranskom moru. Biološka raznolikost deseteronožaca dubljih koraligenih staništa (poput kolonija crvenih koralja) slabo je istražena za razliku od obalnih područja i mekog dna tradicionalnih koćarskih područja. U ovom radu se naglašava korisnost ispitivanja ostataka komercijalne ekstrakcije koralja porijeklom iz prethodno manje istraženih morskih staništa kako bi se poboljšalo znanje o biološkoj raznolikosti takvih staništa

Documenting the spatial and temporal expansion of grouper species in the eastern Adriatic Sea (Croatia) through local ecological knowledge of recreational fishermen

Groupers are important predatory marine fish species, and also economically important to commercial and recreational fisheries, but threatened by overfishing worldwide. The dusky grouper (Epinephelus marginatus) is the most common species that historically occurred in the Southern and central Eastern Adriatic, while other species were mostly restricted to the southern part of the region or were not recorded in the Adriatic Sea. However, the warming of the sea caused by recent climate change has caused some grouper species in the Eastern Adriatic to expand northward. This spread has been poorly documented, largely because rocky coastal habitats, which are less accessible to conventional research methods that often rely on specific fishing gears, have received far less attention than other more accessible habitats i.e. soft bottoms. Reports of recent grouper expansion are primarily anecdotal and mainly based on the extensive observations of recreational fishermen who mainly utilize rocky coastal habitats. In order to gain insight into this phenomenon, we conducted a survey to investigate the distribution of groupers along the Croatian coast of the eastern Adriatic using the Local Ecological Knowledge methodology. Semi-structured interviews were carried out to record fishers’ knowledge and perceptions of changes in their catches, as well as personal observations. The data collected provided information on the spatial and temporal expansion of groupers in the eastern Adriatic over the last 60 years, as perceived by local recreational fishermen

The Influence of Snow Cover Changes on Red Deer (Cervus elaphus L.) Migrations in the Western Part of Gorski Kotar Region in Croatia

Background and Purpose: Animal migrations are a direct result of reproduction, behaviour characteristics, predators, population density, disturbance, loss of habitat, climatic, vegetational and nutritional factors. The availability and accessibility of natural food in winter months is dependent on snow cover. The main objective of this study was to determine the migrational activities of red deer and to examine the dependency between migrations and climatic factors. Materials and Methods: The study was carried out in the northwest Dinarid mountains, i.e. in the western part of Gorski Kotar region, which represents a large integral forest complex, distinctive due to its significant vertical drops, diverse relief characteristics and habitat conditions. Data on red deer migrations was collected over a 12 year period from hunting records, gamekeeper logs and records from game counting and monitoring. Results and Conclusions: The results of the macroclimatic analysis show a statistically significant difference (p<0.05) between the monitored weather stations in the study area. The Klana site stood out as the most appropriate red deer winter habitat, based on climatic conditions. Climatic conditions play a key role in seasonal red deer migrations or non-migrations. The Crni Lug site was assessed to be the least favourable due to macroclimatic conditions (snow depth)

SATELLITE DNA - UKE ELEMENTS DISPERSED WlTHlN EUCHROMATIN OF BEETTE Tribolium castoneum

Satellite DNA - like elements dispersed in the within euchromatin of Tribolium castaneu

Transcriptional activity of repetitive DNA families in the beetle Tribolium castaneum

Satellite DNAs are tandemly repeated sequences clustered within heterochromatin. However, in some cases such as the major TCAST1 satellite DNA from the beetle Tribolium castaneum, they are found partially dispersed within euchromatin. Such organization together with transcriptional activity enables TCAST1 to modulate the activity of neighbouring genes and plays a role in heterochromatin remodelling during development and environmental stress response. In order to explore if other T. castaneum repetitive families have features which could provide them with a possible gene-modulatory role we analyse here transcription activity of ten distinct TCAST families. Transcriptome sequencing (RNA-seq) was performed on total RNA extracted from adult T. castaneum grown at 25°C as well as from adults subjected to 24 h heat stress at 42°C, with 30 min and 1 h of recovery, respectively. For oocytes and embryos we used publicly available dataset (SRA accession number: SRP050428). After sequencing, adapters and low quality reads were removed and mapped using Bowtie2 to dimers of repetitive families. Normalization method used was fragments per kb of transcript per million mapped reads (FPKM) which we calculated manually. Results from RNA-seq were confirmed by qPCR. Our study reveals that low copy TCAST repetitive families, partially dispersed within euchromatin, are transcribed. Their transcriptional activity is increased after heat stress and differs among stages of embryogenesis

Utjecaj kloridnih iona na pasivitet Ti6Al4V legure u biološkom okolišu

Ovaj rad sastoji se od dva dijela: • Teoretskog • Eksperimentalnog U teoretskom dijelu opisana su svojstva titana i njegovih legura. Također, dan je pregled legirnih sustava, te su opisani postupci nastajanja čistog titana. Nadalje, spomenuta je i sve veća primjena titana i njegovih legura u industriji. Naglasak je stavljen na primjenu u medicini. U eksperimentalnom dijelu ispitana je korozijska postojanost legure titana Ti6Al4V u simuliranom biološkom okolišu. Pokušao se utvrditi utjecaj kloridnih iona na stvaranje pasivnog filma na površini legure. Elektrokemijskim ispitivanjima ispitana je njena sklonost rupičastoj koroziji te je na kraju dan zaključak cijelog eksperimenta