Complete genome sequence of the cellulolytic thermophile Clostridium thermocellum DSM1313

Clostridium thermocellum DSM1313 is a thermophilic, anaerobic bacterium with some of the highest rates of cellulose hydrolysis reported. The complete genome sequence reveals a suite of carbohydrate-active enzymes and demonstrates a level of diversity at the species level distinguishing it from the type strain ATCC 27405.     

Cannabinoid CB1 receptor activation mediates the opposing effects of amphetamine on impulsive action and impulsive choice

It is well known that acute challenges with psychostimulants such as amphetamine affect impulsive behavior. We here studied the pharmacology underlying the effects of amphetamine in two rat models of impulsivity, the 5-choice serial reaction time task (5-CSRTT) and the delayed reward task (DRT), providing measures of inhibitory control, an aspect of impulsive action, and impulsive choice, respectively. We focused on the role of cannabinoid CB1 receptor activation in amphetamine-induced impulsivity as there is evidence that acute challenges with psychostimulants activate the endogenous cannabinoid system, and CB1 receptor activity modulates impulsivity in both rodents and humans. Results showed that pretreatment with either the CB1 receptor antagonist/inverse agonist SR141716A or the neutral CB1 receptor antagonist O-2050 dose-dependently improved baseline inhibitory control in the 5-CSRTT. Moreover, both compounds similarly attenuated amphetamine-induced inhibitory control deficits, suggesting that CB1 receptor activation by endogenously released cannabinoids mediates this aspect of impulsive action. Direct CB1 receptor activation by Δ9-Tetrahydrocannabinol (Δ9-THC) did, however, not affect inhibitory control. Although neither SR141716A nor O-2050 affected baseline impulsive choice in the DRT, both ligands completely prevented amphetamine-induced reductions in impulsive decision making, indicating that CB1 receptor activity may decrease this form of impulsivity. Indeed, acute Δ9-THC was found to reduce impulsive choice in a CB1 receptor-dependent way. Together, these results indicate an important, though complex role for cannabinoid CB1 receptor activity in the regulation of impulsive action and impulsive choice as well as the opposite effects amphetamine has on both forms of impulsive behavior.     

Dcm methylation is detrimental to plasmid transformation in Clostridium thermocellum

ABSTRACT: BACKGROUND: Industrial production of biofuels and other products by cellulolytic microorganisms is of interest but hindered by the nascent state of genetic tools. Although a genetic system for Clostridium thermocellum DSM1313 has recently been developed, available methods achieve relatively low efficiency and similar plasmids can transform C. thermocellum at dramatically different efficiencies. RESULTS: We report an increase in transformation efficiency of C. thermocellum for a variety of plasmids by using DNA that has been methylated by Escherichia coli Dam but not Dcm methylases. When isolated from a dam+ dcm+ E. coli strain, pAMG206 transforms C. thermocellum 100-fold better than the similar plasmid pAMG205, which contains an additional Dcm methylation site in the pyrF gene. Upon removal of Dcm methylation, transformation with pAMG206 showed a four- to seven-fold increase in efficiency; however, transformation efficiency of pAMG205 increased 500-fold. Removal of the Dcm methylation site from the pAM205 pyrF gene via silent mutation resulted in increased transformation efficiencies equivalent to that of pAMG206. Upon proper methylation, transformation efficiency of plasmids bearing the pMK3 and pB6A origins of replication increased ca. three orders of magnitude. CONCLUSION: E. coli Dcm methylation decreases transformation efficiency in C. thermocellum DSM1313. The use of properly methylated plasmid DNA should facilitate genetic manipulation of this industrially relevant bacterium.     

Prevalence, causes and socio-economic determinants of vision loss in Cape Town, South Africa

Purpose

To estimate the prevalence and causes of blindness and visual impairment in Cape Town, South Africa and to explore socio-economic and demographic predictors of vision loss in this setting.

Methods

A cross sectional population-based survey was conducted in Cape Town. Eighty-two clusters were selected using probability proportionate to size sampling. Within each cluster 35 or 40 people aged 50 years and above were selected using compact segment sampling. Visual acuity of participants was assessed and eyes with a visual acuity less than 6/18 were examined by an ophthalmologist to determine the cause of vision loss. Demographic data (age, gender and education) were collected and a socio-economic status (SES) index was created using principal components analysis.

Results

Out of 3100 eligible people, 2750 (89%) were examined. The sample prevalence of bilateral blindness (presenting visual acuity <3/60) was 1.4% (95% CI 0.9–1.8). Posterior segment diseases accounted for 65% of blindness and cataract was responsible for 27%. The prevalence of vision loss was highest among people over 80 years (odds ratio (OR) 6.9 95% CI 4.6–10.6), those in the poorest SES group (OR 3.9 95% CI 2.2–6.7) and people with no formal education (OR 5.4 95% CI 1.7–16.6). Cataract surgical coverage was 68% in the poorest SES tertile (68%) compared to 93% in the medium and 100% in the highest tertile.

Conclusions

The prevalence of blindness among people ≥50 years in Cape Town was lower than expected and the contribution of posterior segment diseases higher than previously reported in South Africa and Sub Saharan Africa. There were clear socio-economic disparities in prevalence of vision loss and cataract surgical coverage in this setting which need to be addressed in blindness prevention programs.     

Illness Beliefs Predict Mortality in Patients with Diabetic Foot Ulcers

BackgroundPatients’ illness beliefs have been associated with glycaemic control in diabetes and survival in other conditions.ObjectiveWe examined whether illness beliefs independently predicted survival in patients with diabetes and foot ulceration.MethodsPatients (n = 169) were recruited between 2002 and 2007. Data on illness beliefs were collected at baseline. Data on survival were extracted on 1^st November 2011. Number of days survived reflected the number of days from date of recruitment to 1^st November 2011.ResultsCox regressions examined the predictors of time to death and identified ischemia and identity beliefs (beliefs regarding symptoms associated with foot ulceration) as significant predictors of time to death.ConclusionsOur data indicate that illness beliefs have a significant independent effect on survival in patients with diabetes and foot ulceration. These findings suggest that illness beliefs could improve our understanding of mortality risk in this patient group and could also be the basis for future therapeutic interventions to improve survival.     

Inverse regulation of biofilm formation and swarming motility by Pseudomonas aeruginosa PA14

We previously reported that SadB, a protein of unknown function, is required for an early step in biofilm formation by the opportunistic pathogen Pseudomonas aeruginosa. Here we report that a mutation in sadB also results in increased swarming compared to the wild-type strain. Our data are consistent with a model in which SadB inversely regulates biofilm formation and swarming motility via its ability both to modulate flagellar reversals in a viscosity-dependent fashion and to influence the production of the Pel exopolysaccharide. We also show that SadB is required to properly modulate flagellar reversal rates via chemotaxis cluster IV (CheIV cluster). Mutational analyses of two components of the CheIV cluster, the methyl-accepting chemotaxis protein PilJ and the PilJ demethylase ChpB, support a model wherein this chemotaxis cluster participates in the inverse regulation of biofilm formation and swarming motility. Epistasis analysis indicates that SadB functions upstream of the CheIV cluster. We propose that P. aeruginosa utilizes a SadB-dependent, chemotaxis-like regulatory pathway to inversely regulate two key surface behaviors, biofilm formation and swarming motility.     

Lateralization in Paridae: comparison of a storing and a non-storing species on a one-trial associative memory task

Summary We present evidence of a difference between a storing and non-storing species in lateralization and transfer of spatial memory processing. Using the technique of monocular occlusion, we compared the performance of a food-storing species, the marsh tit (Parus palustris), with a closely related species that does not store food, the blue tit (P. caeruleus), on a task which relies on one-trial learning for the spatial location of hidden food items. In this one-trial associative learning task, the birds had to return to sites in phase II of a trial where they had been allowed to eat some, but not all, of a piece of peanut in phase I. In the first experiment, in which the birds did not wear eye caps, marsh tits required fewer looks in phase II to find the hidden peanut than blue tits. By categorising the sites as seeded, unseeded or not visited in phase I, further analysis suggested that the two species also differ in the way they behave towards the 3 types of site. Marsh tits appear to distinguish between seeded and other sites, irrespective of whether the other sites were known to be empty (unseeded) or not (not visited); whereas blue tits preferentially returned to those sites that have been visited in phase I, irrespective of whether they contained a seed or not. In the second experiment, all birds wore an eye cap on the left or right eye for phase I and II of each trial. For both species, it was demonstrated that although the visual systems fed by both the right and left eye are involved in short-term storage, the right eye system is associated also with long-term storage. Thus, lateralization was found in both blue tits and marsh tits. However, unilateral transfer of these memories was found only in marsh tits, suggesting that there may be a difference between storers and non-storers in the mechanism of memory processing.     

Lateralization and unilateral transfer of spatial memory in marsh tits

Summary The results reported in this paper demonstrate lateralization and transfer of spatial memory processing in an adult, food-storig bird. The technique of monocular occlusion was used to investigate lateralization and memory transfer in food-storing marsh tits (Parus palustris) for two tasks, food-storing and one-trial associative learning, which rely on one-trial learning for the spatial location of hidden food items. In the food-storing task, marsh tits had to return to the sites where they had previously stored a seed; in the one-trial associative learning task, the birds had to return to sites where they had been allowed to eat some, but not all, of a piece of peanut. For both spatial memory tasks, it was demonstrated that although the visual systems fed by both eyes are involved in short-term storage, the right eye system is associated with long-term storage, and that memories are transferred from the left to the right eye system between 3 and 24 h after memory formation.     

Comparison of PCR-based marker systems for the analysis of genetic relationships in cultivated potato

The application of AFLPs, RAPDs and SSRs to examine genetic relationships in the primary northwestern European cultivated potato gene pool was investigated. Sixteen potato cultivars were genotyped using five AFLP primer combinations, 14 RAPD primers, and 17 database-derived SSR primer pairs. All three approaches successfully discriminated between the 16 cultivars using a minimum of one assay. Similarity matrices produced for each marker type on the basis of Nei and Li coefficients showed low correlations when compared with different statistical tests. Dendrograms were produced from these data for each marker system. The usefulness of each system was examined in terms of number of loci revealed (effective multiplex ratio, or EMR) and the amount of polymorphism detected (diversity index, or DI). AFLPs had the highest EMR, and SSRs the highest DI. A single parameter, marker index (MI), which is the product of DI and EMR, was used to evaluate the overall utility of each marker system. The use of these PCR-based marker systems in potato improvement and statutory applications is discussed.Abbreviations: PCR, polymerase chain reaction; AFLP, amplified fragment length polymorphism; RAPD, randomly amplified polymorphic DNA; DNA, deoxyribonucleic acid; EMR, effective multiplex ratio; DI, diversity index; MI, marker index; RFLP, restriction fragment length polymorphism.     

Improved somatic embryo production from embryogenic tissue of Pinus patula

Summary Embryogenic tissue from six genotypes of Pinus patula (Schiede et Deppe) was subjected to a number of treatments to improve both somatic embryo maturation and germination protocols. The use of a slightly modified 240 medium supplemented with polyethylene glycol (PEC) significantly improved both the number and quality of embryos produced, especially at the 7.5 and 10% level. Various pre-germination treatments were tested to enhance embryo germination. A partial drying treatment (PDT) at high relative humidity, lasting approximately 4 wk, gave the best germination results. Despite the beneficial effects of the PDT, embryos that had been harvested from the 240 maturation treatment containing no PEG gave the best germination responses when compared to the PEG-treated cultures. Plantlets were acclimatized ex vitrum, but success rates were low. Latent PEG effects were observed in acclimatized somatic seedlings.