Stunting and flower buds deficiency of Lilium sp.: a new phytoplasma associated disease

The presence of phytoplasmas in Lilium sp. showing severely stunted growth, leaf malformation and flower buds deficiency was demonstrated for the first time using polymerase chain reaction assays with primers amplifying phytoplasma 16S rDNA regions. These phytoplasmas were found in leaves as well as roots and bulb scales of symptomatic and CMV and/or LSV affected and asymptomatic virus-free lilies.     

Detection of Grapevine Viruses in Poland

During a 3‐year study, grapevines from 23 vineyards in Poland were surveyed for virus diseases and tested to determine the prevalence of the most economically important viruses by RT‐PCR. The rate of positive samples was 2.2% for grapevine leafroll‐associated virus 1 (GLRaV‐1), 1.9% for grapevine leafroll‐associated virus 2 (GLRaV‐2), 1.5% grapevine leafroll‐associated virus 3 (GLRaV‐3), 1.9% for grapevine virus A (GVA), 0.2% for grapevine virus B (GVB), 0.2% for grapevine virus E (GVE), 0.65% for grapevine fanleaf virus (GFLV), 20.4% for grapevine fleck virus (GFkV) and 71.9% for grapevine rupestris stem pitting‐associated virus (GRSPaV). These viruses were found to occur as single or mixed infections of different combinations in individual grapevines. The overall viral infection rate in the surveyed grapevines was 82.6%. GRSPaV is the most widely distributed virus of all the viruses currently detected in the region. DNA sequencing confirmed the identification of the viruses in selected samples, and analysis indicated that the Polish isolates shared a close molecular identity with the corresponding isolates in GenBank. To our knowledge, this is the first detection of GLRaV‐1, ‐2, ‐3, GVA, GVB, GVE, GFLV, GFkV and GRSPaV in Poland.     

Free amino acids in basal and vagally stimulated gastric secretion

The concentrations of the individual free amino acids were determined in one hour fraction of basal secretion and peak hydrogen ion secretion following stimulation with 2-deoxy-D-glucose (2-DG) (group I) or insulin (group II). Group I consisted of 9 patients with duodenal ulcer having hypersecretion of gastric acid as determined by histamine test; 7 patients with duodenal ulcer who underwent truncal vagotomy and had insulin test performed two weeks after the operation formed group II. The total concentration of free amino acids was similar in basal and in stimulated gastric juice in both groups. Also the concentrations of the individual amino acids did not change significantly after stimulation. There was, however, a significant increase following stimulation in the output of amino acids both in group I and in group II. This increase was parallel to that in the volume of gastric juice, which suggests that a definite amount of free amino acids is always present in the gastric juice, and that the secretion of these acids is not under vagal control.     

Contribution of topoisomerase I to conversion of single-strand into double-strand DNA breaks

An in vitro system composed of nicked pBR322 DNA and purified topoisomerase I was employed to study the efficiency of the topoisomerase I-driven single-strand to double-strand DNA breaks conversion. At 1.4 × 10⁵ topoisomerase I activity units per mg DNA about 20% single-strand nicks were converted into double-strand breaks during 30 min due to topoisomerase I action. Camptothecin inhibited the conversion. The conversion was also inhibited when the relaxing activity of the used topoisomerase I was increased by phosphorylation of the enzyme with casein kinase 2. The presented data suggest that topoisomerase I may be involved in production of double-stranded breaks in irradiated cells and that this process positively depends on the amount of topoisomerase I but not on its phosphorylation state.     

Effect of pedaling rates and myosin heavy chain composition in the vastus lateralis muscle on the power generating capability during incremental cycling in humans

In this study, we have determined power output reached at maximal oxygen uptake during incremental cycling exercise (P(I, max)) performed at low and at high pedaling rates in nineteen untrained men with various myosin heavy chain composition (MyHC) in the vastus lateralis muscle. On separate days, subjects performed two incremental exercise tests until exhaustion at 60 rev min(-1) and at 120 rev min(-1). In the studied group of subjects P(I, max) reached during cycling at 60 rev min(-1) was significantly higher (p=0.0001) than that at 120 rev min(-1) (287+/-29 vs. 215+/-42 W, respectively for 60 and 120 rev min(-1)). For further comparisons, two groups of subjects (n=6, each) were selected according to MyHC composition in the vastus lateralis muscle: group H with higher MyHC II content (56.8+/-2.79 %) and group L with lower MyHC II content in this muscle (28.6+/-5.8 %). P(I, max) reached during cycling performed at 60 rev min(-1) in group H was significantly lower than in group L (p=0.03). However, during cycling at 120 rev min(-1), there was no significant difference in P(I, max) reached by both groups of subjects (p=0.38). Moreover, oxygen uptake (VO(2)), blood hydrogen ion [H(+)], plasma lactate [La(-)] and ammonia [NH(3)] concentrations determined at the four highest power outputs completed during the incremental cycling performed at 60 as well as 120 rev min(-1), in the group H were significantly higher than in group L. We have concluded that during an incremental exercise performed at low pedaling rates the subjects with lower content of MyHC II in the vastus lateralis muscle possess greater power generating capabilities than the subjects with higher content of MyHC II. Surprisingly, at high pedaling rate, power generating capabilities in the subjects with higher MyHC II content in the vastus lateralis muscle did not differ from those found in the subjects with lower content of MyHC II in this muscle, despite higher blood [H(+)], [La(-)] and [NH(3)] concentrations. This indicates that at high pedaling rates the subjects with higher percentage of MyHC II in the vastus lateralis muscle perform relatively better than the subjects with lower percentage of MyHC II in this muscle.     

Crystal structure of RuvC resolvase in complex with Holliday junction substrate

The key intermediate in genetic recombination is the Holliday junction (HJ), a four-way DNA structure. At the end of recombination, HJs are cleaved by specific nucleases called resolvases. In Gram-negative bacteria, this cleavage is performed by RuvC, a dimeric endonuclease that belongs to the retroviral integrase superfamily. Here, we report the first crystal structure of RuvC in complex with a synthetic HJ solved at 3.75 Å resolution. The junction in the complex is in an unfolded 2-fold symmetrical conformation, in which the four arms point toward the vertices of a tetrahedron. The two scissile phosphates are located one nucleotide from the strand exchange point, and RuvC approaches them from the minor groove side. The key protein–DNA contacts observed in the structure were verified using a thiol-based site-specific cross-linking approach. Compared with known complex structures of the phage resolvases endonuclease I and endonuclease VII, the RuvC structure exhibits striking differences in the mode of substrate binding and location of the cleavage site.     

Regulatory mechanisms underlying novelty-induced grooming in the laboratory rat

Bouts of pelage cleaning can be readily evoked in laboratory rodents under conditions of exposure to novelty. Such novelty-induced grooming is described as stereotyped and rostro-caudal in its progression. The patterned structure of novelty-induced grooming makes it particularly attractive for research on the organizational and motivational underpinnings of co-ordinated behaviour. Micro-characteristics of stereotyped novelty-induced grooming bouts were studied in 27 female Wistar rats that were exposed to a novel arena with shelters for a period of 15 min. The order of grooming acts within the initial bouts was rostro-caudal, but subsequent bouts became progressively disorganized in their sequencing. The observed pattern of progressive bout disorganization may be attributed to the gradual dearousal from stress. Differences between consecutive bouts in their micro-characteristics suggest that at least some grooming actions emitted within the context of those bouts operate as relatively independent units of behaviour. Those unitary component actions appear to be integrated into protracted pelage cleaning sequences by a separate mechanism. Similar endogenous mechanisms have been proposed for other co-ordinated motor actions, which suggests that the organizational principles identified in the context of novelty-induced grooming may represent general principles that govern co-ordinated behaviour.     

The alterations of lipid bilayer fluidity induced by newly synthesized phenothiazine derivative

Using fluorescence spectroscopy, calorimetry and ESR the interactions of the phenothiazine derivative 2-trifluoromethyl-10-(4-[methylsulfonylamid]buthyl)-phenothiazine (FPhMS) with lipids were studied. Calorimetry showed biphasic effect of FPhMS on main phase transition of DPPC. At molar ratios up to 0.06 drug induced decrease of transition temperature and enthalpy, while at higher concentrations it caused subsequent increase of these parameters. For all concentrations studied we observed gradual broadening of transition peaks. Fluorescence polarization revealed that in FPhMS/lipid mixtures, order in bilayers is decreased in the gel state and increased in the liquid crystalline state. ESR experiment showed that at molar ratio of 0.06, FPhMS reduces the mobility of spin probes located in both polar and hydrophobic regions. Comparing observed effects with those reported for cholesterol/lipid mixtures, we conclude that at higher concentrations FPhMS presumably induces a new mode of bilayer packing. This structure is less co-operative than an unperturbed bilayer, but locally the mobility of lipid molecules is decreased.