Effect of Metalaxyl on the incidence and severity of Pearl millet downy mildew disease in Northern Nigeria

Pearl millet downy mildew (DM) incidence, severity and yield losses of two pearl millet varieties (local and improved) due to the disease were determined in the field. Significant differences in the disease incidence and severity were recorded in the plots sown with metalaxyl-treated seeds and those sown with non-treated seeds, indicating the efficacy of the fungicide on the fungus. Yield losses due to non-treatment of seeds with metalaxyl was 40.88 and 45.39% in a local variety and 43.00 and 18.60% in an improved variety in the 2000 and 2001 cropping seasons respectively. Significant differences between plots sown with metalaxyl-treated and those sown with non-treated seeds were obtained for other yield components such as 1000-grains weight, panicle length and weight.     

Gene expression and the evolution of phenotypic diversity in social wasps

Background  

Organisms are capable of developing different phenotypes by altering the genes they express. This phenotypic plasticity provides a means for species to respond effectively to environmental conditions. One of the most dramatic examples of phenotypic plasticity occurs in the highly social hymenopteran insects (ants, social bees, and social wasps), where distinct castes and sexes all arise from the same genes. To elucidate how variation in patterns of gene expression affects phenotypic variation, we conducted a study to simultaneously address the influence of developmental stage, sex, and caste on patterns of gene expression in Vespula wasps. Furthermore, we compared the patterns found in this species to those found in other taxa in order to investigate how variation in gene expression leads to phenotypic evolution.     

Actin stress fibres and cell-cell adhesion molecules in tendons: organisation in vivo and response to mechanical loading of tendon cells in vitro.

Tendons consist of parallel longitudinal rows of cells separated by collagen fibres. The cells are in intimate contact longitudinally within rows, and laterally via sheet-like lateral cell processes between rows. At points of contact, they are linked by gap junctions. Since tendons stretch under load, such cell contacts require protection. Here we describe the organisation of the actin cytoskeleton and actin-based cell-cell interactions in vivo and examine the effect of cyclic tensile loading on tendon cells in vitro. Cells within longitudinal rows contained short longitudinally running actin stress fibres. Each fibre was aligned with similar fibres in the cells longitudinally on either side, and fibres appeared to be linked via adherens junctions. Overall, these formed long oriented rows of stress fibres running along the rows of tendon cells. In culture, junctional components n-cadherin and vinculin and the stress fibre component tropomyosin increased in strained cultures, whereas actin levels remained constant. These results suggest that: (1) cells are linked via actin-associated adherens junctions along the line of principal strain; and (2) under load, cells appear to attach themselves more strongly together, and assemble more of their cytoplasmic actin into stress fibres with tropomyosin. Taken together, this suggests that cell-cell contacts are protected during stretch, and also that the stress fibres, which are contractile, may provide an active mechanism for recovery from stretch. In addition, stress fibres are ideally oriented to monitor tensile load and thus may be important in mechanotransduction and the generation of signals passed via the gap junction network.     

Feeding efficiency of the larval ctenophore Mnemiopsis leidyi A. Agassiz (Ctenophora, Lobata)

Larval stages of the ctenophore Mnemiopsis leidyi rely on metazoanprey, such as Acartia tonsa nauplii and copepodites, to supporthigh growth rates. However, M. leidyi larvae <0.5 mm (totallength) had low retention efficiencies (REs) (proportion ofencountered prey actually ingested), 5.78 ± 2.6% (mean± SE), of nauplii and were often damaged by their encounters.REs of nauplii rapidly increased, 38.94 ± 3.73%, as larvaegrew to a size of     

Capture mechanisms used by the lobate ctenophore, Mnemiopsis leidyi, preying on the copepod Acartia tonsa

Although the lobate ctenophore Mnemiopsis leidyi is an influentialplanktonic predator, the mechanisms enabling it to capture itscharacteristically wide range of prey have not been systematicallyexamined. We recorded interactions between free-swimming M.leidyiand two stages (nauplii, adults) of the calanoid copepod Acartiatonsa in order to determine a mechanistic explanation of thisfeeding process. Prey encounter with Mnemiopsis involved twodifferent processes. The first depended on fluid motions createdby the nearly continuous beating of cilia lining the four auricles.These cilia created a low-velocity flow in which A.tonsa naupliiwere entrained (94% of naupliar encounters) and transportedpast the oral lobes onto the tentillae (oral tentacles). Thenauplii, although capable of rapid escape responses, generallyappeared to be insensitive to the current in which they werecarried. The second process relied upon the collision of swimmingprey with the inner surfaces of the oral lobes and was not obviouslyinfluenced by the auricular feeding currents. Adult A.tonsawere rarely entrained in the auricular flow, but, instead, propelledthemselves into contact with the oral lobes (97% of adult encounters).Both prey capture processes functioned simultaneously. The synergisticfunctioning of these processes probably explains the broad patternsof prey ingestion found by in situ studies of Mnemiopsis feeding.     

A randomised, blinded, placebo-controlled trial in dementia patients continuing or stopping neuroleptics (the DART-AD trial)

Background

There have been increasing concerns regarding the safety and efficacy of neuroleptics in people with dementia, but there are very few long-term trials to inform clinical practice. The aim of this study was to determine the impact of long-term treatment with neuroleptic agents upon global cognitive decline and neuropsychiatric symptoms in patients with Alzheimer disease.

Methods and Findings

Design: Randomised, blinded, placebo-controlled parallel two-group treatment discontinuation trial.Setting: Oxfordshire, Newcastle and Gateshead, London and Edinburgh, United Kingdom.Participants: Patients currently prescribed the neuroleptics thioridazine, chlorpromazine, haloperidol trifluoperazine or risperidone for behavioural or psychiatric disturbance in dementia for at least 3 mo.Interventions: Continue neuroleptic treatment for 12 mo or switch to an identical placebo.Outcome measures: Primary outcome was total Severe Impairment Battery (SIB) score. Neuropsychiatric symptoms were evaluated with the Neuropsychiatric Inventory (NPI).Results: 165 patients were randomised (83 to continue treatment and 82 to placebo, i.e., discontinue treatment), of whom 128 (78%) commenced treatment (64 continue/64 placebo). Of those, 26 were lost to follow-up (13 per arm), resulting in 51 patients per arm analysed for the primary outcome. There was no significant difference between the continue treatment and placebo groups in the estimated mean change in SIB scores between baseline and 6 mo; estimated mean difference in deterioration (favouring placebo) −0.4 (95% confidence interval [CI] −6.4 to 5.5), adjusted for baseline value (p = 0.9). For neuropsychiatric symptoms, there was no significant difference between the continue treatment and placebo groups (n = 56 and 53, respectively) in the estimated mean change in NPI scores between baseline and 6 mo; estimated mean difference in deterioration (favouring continue treatment) −2.4 (95% CI −8.2 to 3.5), adjusted for baseline value (p = 0.4). Both results became more pronounced at 12 mo. There was some evidence to suggest that those patients with initial NPI ≥ 15 benefited on neuropsychiatric symptoms from continuing treatment.

Conclusions

For most patients with AD, withdrawal of neuroleptics had no overall detrimental effect on functional and cognitive status. Neuroleptics may have some value in the maintenance treatment of more severe neuropsychiatric symptoms, but this benefit must be weighed against the side effects of therapy.Trial registration: Cochrane Central Registry of Controlled Trials/National Research Register (#ISRCTN33368770).     

Ice premelting during differential scanning calorimetry

Premelting at the surface of ice crystals is caused by factors such as temperature, radius of curvature, and solute composition. When polycrystalline ice samples are warmed from well below the equilibrium melting point, surface melting may begin at temperatures as low as -15 degrees C. However, it has been reported (. Biophys. J. 65:1853-1865) that when polycrystalline ice was warmed in a differential scanning calorimetry (DSC) pan, melting began at about -50 degrees C, this extreme behavior being attributed to short-range forces. We show that there is no driving force for such premelting, and that for pure water samples in DSC pans curvature effects will cause premelting typically at just a few degrees below the equilibrium melting point. We also show that the rate of warming affects the slope of the DSC baseline and that this might be incorrectly interpreted as an endotherm. The work has consequences for DSC operators who use water as a standard in systems where subfreezing runs are important.     

The cytokine and chemokine expression profile of nucleus pulposus cells: implications for degeneration and regeneration of the intervertebral disc

Introduction

The aims of these studies were to identify the cytokine and chemokine expression profile of nucleus pulposus (NP) cells and to determine the relationships between NP cell cytokine and chemokine production and the characteristic tissue changes seen during intervertebral disc (IVD) degeneration.

Methods

Real-time q-PCR cDNA Low Density Array (LDA) was used to investigate the expression of 91 cytokine and chemokine associated genes in NP cells from degenerate human IVDs. Further real-time q-PCR was used to investigate 30 selected cytokine and chemokine associated genes in NP cells from non-degenerate and degenerate IVDs and those from IVDs with immune cell infiltrates (‘infiltrated’). Immunohistochemistry (IHC) was performed for four selected cytokines and chemokines to confirm and localize protein expression in human NP tissue samples.

Results

LDA identified the expression of numerous cytokine and chemokine associated genes including 15 novel cytokines and chemokines. Further q-PCR gene expression studies identified differential expression patterns in NP cells derived from non-degenerate, degenerate and infiltrated IVDs. IHC confirmed NP cells as a source of IL-16, CCL2, CCL7 and CXCL8 and that protein expression of CCL2, CCL7 and CXCL8 increases concordant with histological degenerative tissue changes.

Conclusions

Our data indicates that NP cells are a source of cytokines and chemokines within the IVD and that these expression patterns are altered in IVD pathology. These findings may be important for the correct assessment of the ‘degenerate niche’ prior to autologous or allogeneic cell transplantation for biological therapy of the degenerate IVD.