Retention of relict satellite DNA sequences in Anemone (Ranunculaceae)

Satellite DNAis a genomic component present in virtually all eukaryotic organisms. The turnover of highly repetitive satellite DNAis an important element in genome organization and evolution in plants. Here we study the presence, physical distribution and abundance of the satellite DNAfamily AhTR1 in Anemone. Twenty-two Anemone accessions were analyzed by PCR to assess the presence of AhTR1, while fluorescence in situ hybridization and Southern hybridization were used to determine the abundance and genomic distribution of AhTR1. The AhTR1 repeat unit was PCR-amplified only in eight phylogenetically related European Anemone taxa of the Anemone section. FISH signal with AhTR1 probe was visible only in A. hortensis and A. pavonina, showing localization of AhTR1 in the regions of interstitial heterochromatin in both species. The absence of a FISH signal in the six other taxa as well as weak signal after Southern hybridization suggest that in these species AhTR1 family appears as relict sequences. Thus, the data presented here support the »library hypothesis« for AhTR1 satellite evolution in Anemone. Similar species-specific satellite DNAprofiles in A. hortensis and A. pavonina support the treatment of A. hortensis and A. pavonina as one species, i.e. A. hortensis s.l

The effect of salinity and osmotic stress on duckweed Lemna minor L.

The response of duckweed (Lemna minor L.) to salinity and osmotic stress was evaluated by monitoring growth and peroxidase activity every second day, for a period of 17 days. The nutrient medium was supplemented with isoosmolar concentrations of NaCl and mannitol (50 mM and 100 mM NaCl, 100 mM and 200 mM mannitol). Growth decreased markedly with increasing concentrations of NaCl and mannitol. The lower concentrations of NaCl (50 mM) and mannitol (100 mM) started to reduce growth significantly in the second week of the experiment, while the higher concentrations (100 and 200 mM) reduced growth from the beginning. Protein concentrations and peroxidase activity fluctuated during the growth period but, most of the time, they were increased in plants treated with NaCl and mannitol. These results suggest that Lemna minor is sensitive to both salinity and osmotic stress. However, the continued growth, and also the increase in peroxidase activity and protein concentration, during the NaCl and mannitol treatments, demonstrate its potential for adaptation to long-term stress. Although salinity and osmotic stress have similar overall effects on Lemna minor, consistent minor differences in growth, protein concentration and peroxidase activity between plants grown on NaCl and those grown on mannitol suggest overlapping, rather than identical, mechanisms of adaptation to salinity and osmotic stress

Usporedba intraplazmidne rekombinacije u bakterijama Agrobacterium tumefaciens i Escherichia coli

In this work we have constructed a plasmid to compare intraplasmid recombination efficiency in Agrobacterium tumefaciens and Escherichia coli. The plasmid contains two directly repeated copies of spectinomycin resistance gene, one lacking 5’ and the other lacking 3’ end. These two copies share a 570-bp region of homology and are separated by the ampicillin resistance gene. Homologous recombination between repeated copies of incomplete spectinomycin resistance genes results in the restoration of spectinomycin resistance. During this process, ampicillin resistance gene is either deleted or incomplete spectinomycin genes are amplified along with the ampicillin resistance gene. This experimental system enabled us to follow for the first time the generation of deletions and amplifications during intraplasmid recombination in A. tumefaciens. We show here that predominantly RecA-independent mechanism contributes to the formation of deletion and amplification products in both, A. tumefaciens and E. coli. Additionally, deletion and amplification products were detected at similar frequencies, suggesting that amplifications and deletions probably occur by a similar mechanism.U ovom smo radu konstruirali plazmid koji nam je omogućio da usporedimo intraplazmidnu rekombinaciju u bakterijama Agrobacterium tumefaciens i Escherichia coli. Plazmid sadržava dvije istosmjerno ponovljene kopije gena odgovornog za rezistenciju na spektinomicin, pri čemu jednoj kopiji nedostaje 5\u27, a drugoj 3\u27 kraj gena, a međusobno su homologne u duljini od 570 pb. Osim toga, DNA koja se nalazi između ove dvije istosmjerno ponovljene sekvencije sadržava gen koji daje rezistenciju na antibiotik ampicilin. Homolognom rekombinacijom između nepotpunih gena za rezistenciju na spektinomicin nastaje funkcionalni gen, odgovoran za pojavu rezistencije. Pritom može doći do delecije gena za rezistenciju na ampicilin ili njegovog umnožavanja, zajedno s nepotpunim genima za otpornost na spektinomicin. Ovaj eksperimentalni sustav omogućio nam je da po prvi put pratimo pojavu delecija i amplifikacija tijekom intraplazmidne rekombinacije u bakteriji A. tumefaciens. Pokazali smo da delecije i amplifikacije u bakterijama Agrobacterium tumefaciens i Escherichia coli nastaju prvenstveno RecA-neovisnim mehanizmom. Osim toga, ustanovili smo da se delecije i amplifikacije pojavljuju s podjednakom učestalošću, što upućuje na to da je mehanizam oba rekombinacijska događaja sličan

The Repetitive DNA Composition in the Natural Pesticide Producer Tanacetum cinerariifolium: Interindividual Variation of Subtelomeric Tandem Repeats

Dalmatian pyrethrum (Tanacetum cinerariifolium (Trevir.) Sch. Bip.), a plant species endemic to the east Adriatic coast, is used worldwide for production of the organic insecticide, pyrethrin. Most studies concerning Dalmatian pyrethrum have focused on its morphological and biochemical traits relevant for breeding. However, little is known about the chromosomal evolution and genome organization of this species. Our study aims are to identify, classify, and characterize repetitive DNA in the T. cinerariifolium genome using clustering analysis of a low coverage genomic dataset. Repetitive DNA represents about 71.63% of the genome. T. cinerariifolium exhibits linked 5S and 35S rDNA configuration (L-type). FISH reveals amplification of interstitial telomeric repeats (ITRs) in T. cinerariifolium. Of the three newly identified satellite DNA families, TcSAT1 and TcSAT2 are located subterminally on most of T. cinerariifolium chromosomes, while TcSAT3 family is located intercalary within the longer arm of two chromosome pairs. FISH reveals high levels of polymorphism of the TcSAT1 and TcSAT2 sites by comparative screening of 28 individuals. TcSAT2 is more variable than TcSAT1 regarding the number and position of FISH signals. Altogether, our data highlights the dynamic nature of DNA sequences associated with subtelomeres in T. cinerariifolium and suggests that subtelomeres represent one of the most dynamic and rapidly evolving regions in eukaryotic genomes

Glycosylation of immunoglobulin G is regulated by a large network of genes pleiotropic with inflammatory diseases

Effector functions of immunoglobulin G (IgG) are regulated by the composition of a glycan moiety, thus affecting activity of the immune system. Aberrant glycosylation of IgG has been observed in many diseases, but little is understood about the underlying mechanisms. We performed a genome-wide association study of IgG N-glycosylation (N = 8090) and, using a data-driven network approach, suggested how associated loci form a functional network. We confirmed in vitro that knockdown of IKZF1 decreases the expression of fucosyltransferase FUT8, resulting in increased levels of fucosylated glycans, and suggest that RUNX1 and RUNX3, together with SMARCB1, regulate expression of glycosyltransferase MGAT3. We also show that variants affecting the expression of genes involved in the regulation of glycoenzymes colocalize with variants affecting risk for inflammatory diseases. This study provides new evidence that variation in key transcription factors coupled with regulatory variation in glycogenes modifies IgG glycosylation and has influence on inflammatory diseases

Comparison of Intraplasmid Rearrangements in Agrobacterium tumefaciens and Escherichia coli

In this work we have constructed a plasmid to compare intraplasmid recombination efficiency in Agrobacterium tumefaciens and Escherichia coli. The plasmid contains two directly repeated copies of spectinomycin resistance gene, one lacking 5’ and the other lacking 3’ end. These two copies share a 570-bp region of homology and are separated by the ampicillin resistance gene. Homologous recombination between repeated copies of incomplete spectinomycin resistance genes results in the restoration of spectinomycin resistance. During this process, ampicillin resistance gene is either deleted or incomplete spectinomycin genes are amplified along with the ampicillin resistance gene. This experimental system enabled us to follow for the first time the generation of deletions and amplifications during intraplasmid recombination in A. tumefaciens. We show here that predominantly RecA-independent mechanism contributes to the formation of deletion and amplification products in both, A. tumefaciens and E. coli. Additionally, deletion and amplification products were detected at similar frequencies, suggesting that amplifications and deletions probably occur by a similar mechanism

The Pontastacus leptodactylus (Astacidae) repeatome provides insight into genome evolution and reveals remarkable diversity of satellite DNA

Pontastacus leptodactylus is a native European crayfish species found in both freshwater and brackish environments. It has commercial importance for fisheries and aquaculture industries. Up till now, most studies concerning P. leptodactylus have focused onto gaining knowledge about its phylogeny and population genetics. However, little is known about the chromosomal evolution and genome organization of this species. Therefore, we performed clustering analysis of a low coverage genomic dataset to identify and characterize repetitive DNA in the P. leptodactylus genome. In addition, the karyogram of P. leptodactylus (2n = 180) is presented here for the first time consisting of 75 metacentric, 14 submetacentric, and a submetacentric/metacentric heteromorphic chromosome pair. We determined the genome size to be at ~18.7 gigabase pairs. Repetitive DNA represents about 54.85% of the genome. Satellite DNA repeats are the most abundant type of repetitive DNA, making up to ~28% of the total amount of repetitive elements, followed by the Ty3/Gypsy retroelements (~15%). Our study established a surprisingly high diversity of satellite repeats in P. leptodactylus. The genome of P. leptodactylus is by far the most satellite-rich genome discovered to date with 258 satellite families described. Of the five mapped satellite DNA families on chromosomes, PlSAT3-411 co-localizes with the AT-rich DAPI positive probable (peri)centromeric heterochromatin on all chromosomes, while PlSAT14-79 co-localizes with the AT-rich DAPI positive (peri)centromeric heterochromatin on one chromosome and is also located subterminally and intercalary on some chromosomes. PlSAT1-21 is located intercalary in the vicinity of the (peri)centromeric heterochromatin on some chromosomes, while PlSAT6-70 and PlSAT7-134 are located intercalary on some P. leptodactylus chromosomes. The FISH results reveal amplification of interstitial telomeric repeats (ITRs) in P. leptodactylus. The prevalence of repetitive elements, especially the satellite DNA repeats, may have provided a driving force for the evolution of the P. leptodactylus genome