A new clade of Dickeya spp. plays a major role in potato blackleg outbreaks in North Finland

Until recently Dickeya was regarded as a pathogen not established in Finland. As a result the blackleg symptom observed on potato was often associated with Pectobacterium atrosepticum. The occurrence of Dickeya spp. on potato in Finland was first reported in 2004. Since then the prevalence of Dickeya has been monitored through surveys and routine test of seed lots produced in the country. The results of monitoring of Dickeya spp. in seed lots produced in Finland between the years 2004 and 2008 indicated a steady increase in the incidence of Dickeya spp. The highest incidence was observed in samples from the 2006 growing season where about 37% were positive for Dickeya spp. The summer in 2006 was one of the warmest summers recorded in 100 years in Finland. The majority of infected lots were imported varieties. Since recently heavy blackleg outbreaks have occurred in production fields in the High Grade (HG) zone. A detailed study of these incidents of blackleg outbreaks in North Finland during the years 2008 and 2010 indicated that Dickeya spp. was the major component in the observed blackleg complex. It was detected and isolated from almost all symptomatic plants investigated. Repetitive sequences PCR (REP‐PCR) and Pulsed Field Gel Electrophoresis (PFGE) analysis of strains isolated in Finland showed identical pattern with those isolated recently in other European countries with a proposed name ‘Dickeya solani’. Moreover, the dnaX gene sequence of the representative strains isolated in Finland indicated 100% similarity to the dnaX sequences of ‘D. solani’. The study presents the first report of a detailed analysis of bacteria involved in potato blackleg complex from natural field outbreaks in North Finland HG zone and characterisation of the ‘D. solani’ strains playing the major role in the disease complex.     

Spectrophotometric titrations of micellar Schiff''s bases prepared from pyridoxal 5′-phosphate

Electron absorption and equilibrium of the Schiffs bases prepared between pyridoxal 5′-phosphate (PLP) and dodecylamine (DODA) or some other shorter chain amines have been studied in nonionic and cationic micellar solutions with various pH of the bulk solution. In the presence of the nonionic (Triton X-100) micelles the Schiffs bases formed between PLP and DODA were embedded into the micelles because the absorption occured at 335 nm, indicative of the nonpolar milieu. This absorption was constant at pH 5–10. At pH 3–5, the tautomeric form absorbing at 415 nm appeared. This resembles the titration of glycogen phosphorylate or that of Schiffs bases in methanol. Short chain amines absorbed at 415 nm, which is typical of Schiffs bases in aqueous solutions. Tryptophan also absorbed first at 415 nm but the absorption changed to 325 nm with a half-time of ～20 min. This was interpreted as being due to formation of the cyclic structure catalysed by micelles. The pH-dependent equilibrium constant of the reaction between PLP and DODA in Triton X-100 solution had a maximum at pH9, the value being 3500 M^?1, about ten times greater than the value of ethylamine at the same pH. Spectral properties of PLP-DODA imines in the cationic micelles (cetyltrimethylammonium bromide) resembled those in the nonionic micelles, except that at low pH the absorption peak in the 415 nm region did not appear. The equilibrium constant of PLP-DODA had maximum at pH 9, the value being as high as 118000 M^?1. Different properties of nonionic and cationic micelles and the design of micellar model systems of PLP enzymes are discussed.     

Seasonal depth distribution and thermal experience of the non-indigenous round goby Neogobius melanostomus in the Baltic Sea: implications to key trophic relations

Biological Invasions - Native to the Ponto-Caspian region, the benthic round goby (Neogobius melanostomus) has invaded several European inland waterbodies as well as the North American Great Lakes...     

Splicing of the adenovirus-2 E1A 13S mRNA requires a minimal intron length and specific intron signals.

The adenovirus E1A region encodes three overlapping mRNAs, designated 9S, 12S and 13S. They differ from each other with regard to the length of the intron which is removed by RNA splicing. We have constructed E1A genes with deletions and insertions in the intervening sequence that is common to all three E1A mRNAs, in a search for signals which influence splicing of the 13S mRNA. Mutant plasmids were transfected into HeLa cells and the transiently expressed E1A mRNAs characterized by the S1 protection assay. The results show that five upstream and 20 downstream nucleotides are sufficient to allow for a correct utilization of the 5'-splice junction for the E1A 13S mRNA. Moreover, we show that a minimal intron length of 78 nucleotides is required for efficient 13S mRNA splicing. The ability of mutants with large intron deletions to maturate a 13S mRNA could partially be restored by expanding the intron length with phage lambda sequences. However, in no case was the normal splicing efficiency obtained with these mutants. In contrast, one mutant in which sequences from the authentic 13S mRNA intron were used to expand the intron expressed almost normal levels of 13S mRNA, thus suggesting that signals which specifically promote 13S mRNA splicing exist.     

Excess copper predisposes photosystem II to photoinhibition in vivo by outcompeting iron and causing decrease in leaf chlorophyll

Photoinhibition of photosystem II was studied in vivo with bean (Phaseolus vulgaris) plants grown in the presence of 0.3 (control), 4, or 15 microM Cu(2+). Although photoinhibition, measured in the presence of lincomycin to block concurrent recovery, is faster in leaves of Cu(2+)-treated plants than in control leaves, thylakoids isolated from Cu-treated plants did not show high sensitivity to photoinhibition. Direct effects of excess Cu(2+) on chloroplast metabolism are actually unlikely, because the Cu concentration of chloroplasts of Cu-treated plants was lower than that of their leaves. Excess Cu in the growth medium did not cause severe oxidative stress, collapse of antioxidative defenses, or loss of photoprotection. Thus, these hypothetical effects can be eliminated as causes for Cu-enhanced photoinhibition in intact leaves. However, Cu treatment lowered the leaf chlorophyll (Chl) concentration and reduced the thylakoid membrane network. The loss of Chl and sensitivity to photoinhibition could be overcome by adding excess Fe together with excess Cu to the growth medium. The addition of Fe lowered the Cu(2+) concentration of the leaves, suggesting that Cu outcompetes Fe in Fe uptake. We suggest that the reduction of leaf Chl concentration, caused by the Cu-induced iron deficiency, causes the high photosensitivity of photosystem II in Cu(2+)-treated plants. A causal relationship between the susceptibility to photoinhibition and the leaf optical density was established in several plant species. Plant species adapted to high-light habitats apparently benefit from thick leaves because the rate of photoinhibition is directly proportional to light intensity, but photosynthesis becomes saturated by moderate light.     

In vivo effects of N/OFQ(1–13)NH2 and its structural analogue [ORN9]N/OFQ(1–13)NH2 on carrageenan-induced inflammation: rat-paw oedema and antioxidant status

The effects of nociceptin(1–13)NH₂ (N/OFQ(1–13)NH₂) and its structural analogue [Orn⁹]N/OFQ(1–13)NH₂ on acute carrageenan (CG)-induced peripheral inflammation and paw antioxidant status were studied. CG was injected intraplantarly in the right hind paw of rats and the volume of the inflamed paw was measured each 30 min for a period of 4h. When administered simultaneously with CG, N/OFQ(1–13)NH₂ decreased the paw volume, whereas if injected 15 min before CG it had no effect. [Orn₉]N/OFQ(1–13)NH₂ produced the opposite effects at the same time-intervals of its administration. We also investigated whether these neuropeptides influence CG-induced changes in cell antioxidant system, especially at the 4th hour of CG administration. CG alone decreased the glutathione level and superoxide dismutase activity, as measured in post-nuclear homogenate of the inflamed paw. However, CG injection increased glutathione peroxidase and glucose-6-phospate dehydrogenase activities, while the activity of glutathione reductase was unchanged. The peptides themselves did not change all measured parameters. Moreover, neither N/OFQ(1–13)NH₂ nor [Orn⁹]N/OFQ(1–13)NH₂ modified CG-induced changes in the antioxidant status, regardless of the time of their injection (simultaneously or 15 min before CG). The present results suggest that N/OFQ(1–13)NH₂ and [Orn⁹]N/OFQ(1–13)NH₂ most likely affect the neuronal inflammation, rather than act as pro- or antioxidants.