Peroxidase activity and structural transitions of cytochrome c bound to cardiolipin-containing membranes

During apoptosis, cytochrome c (cyt c) is released from intermembrane space of mitochondria into the cytosol where it triggers the caspase-dependent machinery. We discovered that cyt c plays another critical role in early apoptosis as a cardiolipin (CL)-specific oxygenase to produce CL hydroperoxides required for release of pro-apoptotic factors [Kagan, V. E., et al. (2005) Nat. Chem. Biol. 1, 223-232]. We quantitatively characterized the activation of peroxidase activity of cyt c by CL and hydrogen peroxide. At low ionic strength and high CL/cyt c ratios, peroxidase activity of the CL/cyt c complex was increased >50 times. This catalytic activity correlated with partial unfolding of cyt c monitored by Trp(59) fluorescence and absorbance at 695 nm (Fe-S(Met(80)) band). The peroxidase activity increase preceded the loss of protein tertiary structure. Monounsaturated tetraoleoyl-CL (TOCL) induced peroxidase activity and unfolding of cyt c more effectively than saturated tetramyristoyl-CL (TMCL). TOCL/cyt c complex was found more resistant to dissociation by high salt concentration. These findings suggest that electrostatic CL/cyt c interactions are central to the initiation of the peroxidase activity, while hydrophobic interactions are involved when cyt c's tertiary structure is lost. In the presence of CL, cyt c peroxidase activity is activated at lower H(2)O(2) concentrations than for isolated cyt c molecules. This suggests that redistribution of CL in the mitochondrial membranes combined with increased production of H(2)O(2) can switch on the peroxidase activity of cyt c and CL oxidation in mitochondria-a required step in execution of apoptosis.     

Multiparametric magnetic resonance imaging-guided salvage radiotherapy in prostate cancer

AimTo analyse the efficacy and toxicity of postprostatectomy SRT in patients with a BCR evaluated with mpMRI.BackgroundMultiparametric magnetic resonance imaging (mpMRI) has the ability to detect the site of pelvic recurrence in patients with biochemical recurrence (BCR) after radical prostatectomy (RP). However, we do not know the oncological outcomes of mpMRI-guided savage radiotherapy (SRT).ResultsLocal, lymph node, and pelvic bone recurrence was observed in 13, 4 and 2 patients, respectively. PSA levels were significantly lower in patients with negative mpMRI (0.4 ng/mL [0.4]) vs. positive mpMRI (2.2 ng/mL [4.1], p = 0.003). Median planning target volume doses in patients with visible vs. non-visible recurrences were 76 Gy vs. 70 Gy. Overall, mean follow-up was 41 months (6–81). Biochemical relapse-free survival (bRFS) at 3 years was 82.3% and 82.5%, respectively, for the negative and positive mpMRI groups (p = 0.800). Three-year rates of late grade ≥2 urinary and rectal toxicity were 14.8% and 1.9%, respectively; all but one patient recovered without sequelae.ConclusionSRT to the macroscopic recurrence identified by mpMRI is a feasible and well-tolerated option. In this study, there were no differences in bRFS between MRI-positive and MRI-negative patients, indicating effective targeting of MRI-positive lesions.     

Fetal cells in the maternal blood

Summary In an attempt to stimulate fetal cells in the maternal blood to mitotic division, peripheral blood lymphocytes were cultured from ten primiparous women and six multiparous women. In the case of the ten primiparous women, PWM was used to stimulate lymphocytes in 3- and 7-day cultures made at the 16th, 20th, 24th, and 28th week of gestation. Altogether, 10565 mitoses were analyzed after quinacrine staining of cells from five mothers who each subsequently gave birth to a male infant, and not a single XY mitosis was found.In the case of the multiparous women, lymphocyte cultures, with PHA or LPS as mitogen and MLC, were initiated between the 13th and 20th week of pregnancy. Four of the mothers were pregnant with a male child, and two with a female child. From cultures of each of the four mothers expecting a boy, a total of 9721 mitoses were analyzed after quinacrine staining, and not a single XY mitosis was found. However, one XY cell was found in the culture from one of the two women who delivered a girl. The XY mitosis probably originated from a pregnancy 8 months earlier which terminated in a male infant.In an attempt to culture and obtain good chromosome preparations from small numbers of cells, it was shown that a good mitotic response and good chromosome preparations could be obtained from as few as 6000 lymphocytes.     

Didymodon vulcanicus J.A.Jiménez,Hedd. & Frank Müll. (Pottiaceae), a new species from tropical Africa

Didymodon vulcanicus J.A.Jiménez, Hedd. & Frank Müll. is described and illustrated as a new species from volcanic regions of tropical Africa. The species is distinguished morphologically by its lanceolate or more rarely ovate-lanceolate leaves that are strongly incurved distally when dry, acute apices, upper and middle laminal cells arranged in longitudinal rows with a low dorsal papilla over the transverse walls which reaches the two immediate cells, basal cells not or hardly differentiated from the medial cells, and the presence of gemmae in the leaf axils. Drawings and light microscope photographs of the main characters are given, and possible confusion with other closely related taxa is discussed.     

Relationship between assemblages of mycorrhizal fungi and bacteria on grass roots

Soils support an enormous microbial diversity, but the ecological drivers of this diversity are poorly understood. Interactions between the roots of individual grass species and the arbuscular mycorrhizal (AM) fungi and bacteria in their rhizoplane were studied in a grazed, unimproved upland pasture. Individual root fragments were isolated from soil cores, DNA extracted and used to identify plant species and assess rhizoplane bacterial and AM fungal assemblages, by amplifying part of the small-subunit ribosomal RNA gene, followed by terminal restriction fragment length polymorphism analysis. For the first time we showed that AM fungal and bacterial assemblages are related in situ and that this relationship occurred at the community level. Principal coordinate analyses of the data show that the AM fungi were a major factor determining the bacterial assemblage on grass roots. We also report a strong influence of the composition of the plant community on AM fungal assemblage. The bacterial assemblage was also influenced by soil pH and was spatially structured, whereas AM fungi were influenced neither by the bacteria nor by soil pH. Our study shows that linkages between plant roots and their microbial communities exist in a complex web of interactions that act at individual and at community levels, with AM fungi influencing the bacterial assemblage, but not the other way round.     

Long-Term Persistence and Leaching of Escherichia coli in Temperate Maritime Soils

Enteropathogen contamination of groundwater, including potable water sources, is a global concern. The spreading on land of animal slurries and manures, which can contain a broad range of pathogenic microorganisms, is considered a major contributor to this contamination. Some of the pathogenic microorganisms applied to soil have been observed to leach through the soil into groundwater, which poses a risk to public health. There is a critical need, therefore, for characterization of pathogen movement through the vadose zone for assessment of the risk to groundwater quality due to agricultural activities. A lysimeter experiment was performed to investigate the effect of soil type and condition on the fate and transport of potential bacterial pathogens, using Escherichia coli as a marker, in four Irish soils (n = 9). Cattle slurry (34 tonnes per ha) was spread on intact soil monoliths (depth, 1 m; diameter, 0.6 m) in the spring and summer. No effect of treatment or the initial soil moisture on the E. coli that leached from the soil was observed. Leaching of E. coli was observed predominantly from one soil type (average, 1.11 ± 0.77 CFU ml⁻¹), a poorly drained Luvic Stagnosol, under natural rainfall conditions, and preferential flow was an important transport mechanism. E. coli was found to have persisted in control soils for more than 9 years, indicating that autochthonous E. coli populations are capable of becoming naturalized in the low-temperature environments of temperate maritime soils and that they can move through soil. This may compromise the use of E. coli as an indicator of fecal pollution of waters in these regions.The contamination of groundwater, including potable water supplies, with microbial pathogens continues to be a global concern (52, 59). Of particular importance in developed countries are the high levels of contamination associated with small-scale and very-small-scale drinking water supplies (5, 19, 57), often groundwater, which serve an estimated 10% of the total population in the European Union (13). The high numbers of these water supplies found to be contaminated with fecal bacteria and thus considered to be unfit for human consumption are worrying because the water from them is often untreated or inadequately treated prior to consumption. Microbial pathogens are known to survive for considerable periods of time in groundwater (29), which increases the health risk due to utilization of contaminated supplies. There are various sources of contamination, but evidence suggests that contamination from the spreading of animal slurries and manures on land can be a significant contributor (3, 33, 53). Spreading of agricultural slurries and manures on land is used by the agricultural sector as a means of nutrient recycling. The health risks associated with the spreading of animal and human wastes containing enteric pathogens have been recognized for a long time (10, 18). Animal manure and wastewaters may contain a broad range of pathogenic microorganisms, including Escherichia coli O157:H7, Campylobacter, Cryptosporidium, Salmonella spp., and pathogenic viruses, which are released into the environment during spreading (15, 22, 55). The levels and incidence of pathogens present in animal manures and slurries are influenced by a number of factors, including herd health, age demographics, stress factors, diet, season, and manure management and storage (37, 39).Soils (and subsoils) often act as a zone for mitigating microbial contamination of groundwater associated with the spreading of animal slurries and manures on land. Some of the pathogenic microorganisms applied to agricultural soils have, however, been observed to leach through the soil into groundwater, which can affect drinking water quality and pose a risk to public health (16, 26, 28, 42, 50), confirming that soil is not always a sufficient obstruction for protection of groundwater (16, 53). Consequently, characterization of the movement of pathogens through the unsaturated soil and subsoil zone (vadose zone) has become critical for assessment of the risk to groundwater posed by agricultural activities (8, 14, 42). The soil and subsoil type is believed to be a major factor influencing the potential transfer of pathogens through soil to groundwater (3, 34, 41, 50). The preapplication moisture status of a soil, which may be influenced by the season, also impacts pathogen survival, fate, and transport (2, 11, 43, 54).E. coli is widely used as an indicator of fecal contamination of water, and certain strains are known to be pathogenic (12). Thus, characterizing this organism''s transport through soil is important because of the health risk posed by the organism itself and with regard to its validity as an indicator of the fate of enteropathogens in the environment. E. coli strains have diverse properties and capabilities that affect their survival and transport in soils (9, 36, 56, 60). Consequently, data obtained by using total E. coli rather than individual surrogate strains can be more representative of the fate and transport of E. coli present in animal slurries. E. coli O157 die-off in soils has been reported to be the same as or quicker than total E. coli die-off, suggesting that data for total E. coli provide a conservative estimate of the survival potential (38, 56). Although many field and laboratory studies have investigated E. coli transport through soil columns (4, 6, 16, 43, 46, 47, 50, 51), most studies have investigated transport through soil to a depth of less than 30 cm. For assessment of the risk of transport to groundwater, such studies may not take into account the variation in soil physical and chemical characteristics with depth (e.g., the frequency and continuity of macropores, organic matter, and moisture contents) that affect bacterial transport. Furthermore, rainfall was often simulated in previous studies, which allows experimental conditions to be controlled but may not be representative of the risk due to variable natural rainfall events over time. In this study, we used intact soil monoliths that were 1 m deep to assess the risk of leaching of total E. coli in four representative Irish soil types under natural rainfall and environmental conditions.The objective of this study was to quantitatively investigate the impact of soil type and season (soil moisture content) on the fate and transport of E. coli spread on four different temperate maritime soil types under natural rainfall conditions. We hypothesized that there would be a greater microbial risk to underlying groundwater with better-drained soil types than with relatively poorly drained soil types following the application of animal slurry. In addition, we hypothesized that E. coli cells spread on wetter spring soils would be transported in greater numbers than E. coli cells spread on drier soils in the summer.     

The maintenance of extreme amino acid diversity at the disease resistance gene, RPP13, in Arabidopsis thaliana

We have used the naturally occurring plant-parasite system of Arabidopsis thaliana and its common parasite Peronospora parasitica (downy mildew) to study the evolution of resistance specificity in the host population. DNA sequence of the resistance gene, RPP13, from 24 accessions, including 20 from the United Kingdom, revealed amino acid sequence diversity higher than that of any protein coding gene reported so far in A. thaliana. A significant excess of amino acid polymorphism segregating within this species is localized within the leucine-rich repeat (LRR) domain of RPP13. These results indicate that single alleles of the gene have not swept through the population, but instead, a diverse collection of alleles have been maintained. Transgenic complementation experiments demonstrate functional differences among alleles in their resistance to various pathogen isolates, suggesting that the extreme amino acid polymorphism in RPP13 is maintained through continual reciprocal selection between host and pathogen.     

Extreme climatic events change the dynamics and invasibility of semi-arid annual plant communities

Extreme climatic events represent disturbances that change the availability of resources. We studied their effects on annual plant assemblages in a semi-arid ecosystem in north-central Chile. We analysed 130 years of precipitation data using generalised extreme-value distribution to determine extreme events, and multivariate techniques to analyse 20 years of plant cover data of 34 native and 11 exotic species. Extreme drought resets the dynamics of the system and renders it susceptible to invasion. On the other hand, by favouring native annuals, moderately wet events change species composition and allow the community to be resilient to extreme drought. The probability of extreme drought has doubled over the last 50 years. Therefore, investigations on the interaction of climate change and biological invasions are relevant to determine the potential for future effects on the dynamics of semi-arid annual plant communities.     

ent-Rosane and abietane diterpenoids as cancer chemopreventive agents

Two ent-rosane- (cuzcol, 1 and 6-dehydroxycuzcol, 2) and a abietatriene- (salvadoriol, 3) type diterpenoids have been isolated from Maytenus cuzcoina and Crossopetalum uragoga, respectively, along with five known diterpene compounds (4-8). Their stereostructures have been elucidated on the basis of spectroscopic analysis, including 1D and 2D NMR techniques, and computational data. The absolute configuration of cuzcol was determined by application of Riguera ester procedure. This is the first instance of isolation of ent-rosane diterpenoids from species of the Celastraceae. The isolated diterpenes were found to be potent anti-tumour-promoter agents, and carnosol (7) also showed a remarkable chemopreventive effect in an in vivo two-stage carcinogenesis model.