Diatoms are important contributors to the benthic microeukaryote flora. This manuscript lays the foundation for future metagenomic and environmental sequencing projects off coastal China by curating diatom DNA sequences from the Yantai region of the Bohai and Yellow Seas ( Northeast China) . These studies are based on cultures established from samples collected in different seasons from marine littoral and supralittoral zones in 2013 and 2014. Thirty-six diatom strains were cultured successfully and identification of these clones was determined by light and scanning electron microscopy( LM and SEM) and DNA sequencing of the nuclear-encoded small subunit ribosomal RNA ( SSU) and chloroplast-encoded rbcL and psbC genes. The strains primarily represent raphid pennate genera, such as Amphora, Amphora ( Oxyamphora) , Caloneis, Diploneis, Halamphora, Navicula, Nitzschia, Parlibellus, Pleurosigma, Surirella and Tryblionella. When the DNA markers from these strains were analysed in a multi-gene phylogeny, we found that some clones-particularly within the genera Amphora, Navicula and Nitzschia-show greater than expected genetic diversity despite their very similar morphology and morphometrics. We also compared the molecular and morphological identities of several seemingly ubiquitous marine littoral taxa in the genera Amphora and Nitzschia from the Indian Ocean and Atlantic Ocean, the Red Sea and Adriatic Sea to their Yellow Sea counterparts.

Tandemly arrayed non-coding sequences or satellite DNAs (satDNAs) are rapidly evolving segments of eukaryotic genomes, including the centromere, and may raise a genetic barrier that leads to speciation. However, determinants and mechanisms of satDNA sequence dynamics are only partially understood. Sequence analyses of a library of five satDNAs common to the root-knot nematodes Meloidogyne chitwoodi and M. fallax together with a satDNA, which is specific for M. chitwoodi only revealed low sequence identity (32–64%) among them. However, despite sequence differences, two conserved motifs were recovered. One of them turned out to be highly similar to the CENP-B box of human alpha satDNA, identical in 10–12 out of 17 nucleotides. In addition, organization of nematode satDNAs was comparable to that found in alpha satDNA of human and primates, characterized by monomers concurrently arranged in simple and higher-order repeat (HOR) arrays. In contrast to alpha satDNA, phylogenetic clustering of nematode satDNA monomers extracted either from simple or from HOR array indicated frequent shuffling between these two organizational forms. Comparison of homogeneous simple arrays and complex HORs composed of different satDNAs, enabled, for the first time, the identification of conserved motifs as obligatory components of monomer junctions. This observation highlights the role of short motifs in rearrangements, even among highly divergent sequences. Two mechanisms are proposed to be involved in this process, i.e., putative transposition-related cut-and-paste insertions and/or illegitimate recombination. Possibility for involvement of the nematode CENP-B box-like sequence in the transposition-related mechanism and together with previously established similarity of the human CENP-B protein and pogo-like transposases implicate a novel role of the CENP-B box and related sequence motifs in addition to the known function in centromere protein binding.

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The taxonomic composition and structure of a marine epilithic diatom community were sampled from the bottom of the two sites at monthly intervals from January to December 2011 in the small semi-enclosed oligotrophic Neum Bay in Bosnia and Herzegovina (Middle Adriatic). Altogether, 264 diatom taxa (species and infraspecific taxa) within 69 genera were identified. Among them, 149 and 203 taxa occurred in samples from the shallow (0.5 m depth) and deep (8 m depth) sites, respectively. The monthly distribution of most of the diatoms was irregular and high numbers of sporadic taxa were found. SIMPER analysis indicated that the difference between shallow and deep sites could be largely attributed to the frequently recorded diatom taxa and those with high percentage abundances. They were Halamphora coffeiformis, Caloneis excentrica, Cocconeis scutellum var. scutellum, Licmophora flabellata, Licmophora gracilis, Licmophora sp., Navicula abunda, Rhabdonema adriaticum, and Striatella unipunctata. Canonical Correspondence Analysis (CCA) showed that temperature, oxygen saturation (O 2 /O 2 ′), silicate concentration (SiO 4 ), and salinity were the most important factors influencing diatom community structure in the bay.

The objective of this work was to contribute to the knowledge of microphytobenthos in the Adriatic Sea, by studying for the first time the benthic diatom communities in Neum Bay in Bosnia and Herzegovina. For this purpose, the benthic diatoms naturally growing on stones and macroalgae were identified at one station in the small semi-enclosed oligotrophic Neum Bay during 2010 and 2011. A total of 24 samples were collected at two different depths, 0.5 m and 8 m, and analysed with light and scanning electron microscopy. Altogether, 425 pennate and 58 centric taxa (species and infraspecific taxa) belonging to 60 families and 115 genera were noted. Genera with the greatest number of taxa were: Mastogloia (46 taxa), Navicula (36), Diploneis (35), Nitzschia (34), Amphora (31), Cocconeis (27), Achnanthes (14), Halamphora (12), Lyrella (11), and Surirella and Licmophora (10 each). Amphora bigibba var. interrupta and Cocconeis scutellum were the most frequent taxa, being present in 87.5% of the samples. In total, 142 taxa were found only once (sporadic taxa). Although benthic diatom richness is high in the bay, taxa are apparently not distributed evenly temporally. Consistent quantitative and qualitative data are still needed for a better determination of the seasonal and spatial changes of the epilithic assemblages in the region. Cilj rada bio je doprinijeti poznavanju mikrofitobentosa u Jadranskom moru istražujući po prvi put bentoske dijatomejske zajednice u Neumskom zaljevu u Bosni i Hercegovini. Bentoske dijatomeje su određene na jednoj postaji u poluzatvorenom oligotrofnom Neumskom zaljevu 2010. i 2011. Sakupljeno je 24 uzoraka na dubinama 0,5 i 8 m, a analizirani su s pomoću svjetlosnog i skenirajućeg elektronskog mikroskopa. U uzorcima je utvrđeno 425 penatnih i 58 centričnih svojti (vrsta i nižih taksonomskih kategorija) dijatomeja unutar 60 porodica i 115 rodova. Najveći broj svojti nađen je unutar sljedećih rodova: Mastogloia (46 svojti), Navicula (36), Diploneis (35), Nitzschia (34), Amphora (31), Cocconeis (27), Achnanthes (14), Halamphora (12), Lyrella (11) te Surirella i Licmophora (svaki po 10 svojti). Najčešće svojte su Amphora bigibba var. interrupta i Cocconeis scutellum s 87,5% učestalosti u ukupnom broju uzoraka. Utvrđene su 142 sporadične svojte (utvrđene u samo jednom uzorku). Iako je broj svojti relativno visok, nije utvrđena pravilnost u njihovoj vremenskoj raspodjeli. Radi preciznijeg utvrđivanja sezonskih i prostornih promjena strukture epilitskih dijatomejskih zajednica, potrebni su detaljniji kvalitativni i kvantitativni podaci.Ključne riječi: Bacillariophyta, plitki oligotrofni zaljev, taksonomska istraživanja, bogatstvo svojti,