Variability in host plant resistance of Sorghum to Striga Hermonthica infestation in West Africa

Fourteen elite sorghum lines were evaluated for their resistance to Striga hermonthica at three locations in Nigeria and Mali. Results showed that many of the lines especially MALISOR 84-1, SAMSORG 41, 97-SB-F5DT-64 (Keninkédié) and the check SRN 39 remained resistant to Striga in all locations with low emerged Striga counts, while SAMSORG 14 had the highest Striga infestation in all locations. Considerable variation in reaction to Striga infestation was observed on Séguètana, 97-SB-F5DT-63 (Wasa), 97-SB-F5DT-65, CMDT 38, CMDT 39 and CMDT 45 which were susceptible to Striga at Samaru, Nigeria but were resistant to Striga at both locations in Mali. Based on low Striga resistance and high grain yield, lines MALISOR 84-1, SAMSORG 41, 97-SB-F5DT-64, 97-SB-F5DT-65, CMDT 39 and SAMSORT 14 have been nominated for wider evaluation across more West African countries.     

Dopamine modulates the plasticity of mechanosensory responses in Caenorhabditis elegans

Dopamine-modulated behaviors, including information processing and reward, are subject to behavioral plasticity. Disruption of these behaviors is thought to support drug addictions and psychoses. The plasticity of dopamine-mediated behaviors, for example, habituation and sensitization, are not well understood at the molecular level. We show that in the nematode Caenorhabditis elegans, a D1-like dopamine receptor gene (dop-1) modulates the plasticity of mechanosensory behaviors in which dopamine had not been implicated previously. A mutant of dop-1 displayed faster habituation to nonlocalized mechanical stimulation. This phenotype was rescued by the introduction of a wild-type copy of the gene. The dop-1 gene is expressed in mechanosensory neurons, particularly the ALM and PLM neurons. Selective expression of the dop-1 gene in mechanosensory neurons using the mec-7 promoter rescues the mechanosensory deficit in dop-1 mutant animals. The tyrosine hydroxylase-deficient C. elegans mutant (cat-2) also displays these specific behavioral deficits. These observations provide genetic evidence that dopamine signaling modulates behavioral plasticity in C. elegans.     

Generalized linear mixture models for handling nonignorable dropouts in longitudinal studies

This paper presents a method for analysing longitudinal data when there are dropouts. In particular, we develop a simple method based on generalized linear mixture models for handling nonignorable dropouts for a variety of discrete and continuous outcomes. Statistical inference for the model parameters is based on a generalized estimating equations (GEE) approach (Liang and Zeger, 1986). The proposed method yields estimates of the model parameters that are valid when nonresponse is nonignorable under a variety of assumptions concerning the dropout process. Furthermore, the proposed method can be implemented using widely available statistical software. Finally, an example using data from a clinical trial of contracepting women is used to illustrate the methodology.     

Two common nonsynonymous paraoxonase 1 (<Emphasis Type="Italic">PON1</Emphasis>) gene polymorphisms and brain astrocytoma and meningioma

Background  

Human serum paraoxonase 1 (PON1) plays a major role in the metabolism of several organophosphorus compounds. The enzyme is encoded by the polymorphic gene PON1, located on chromosome 7q21.3. Aiming to identify genetic variations related to the risk of developing brain tumors, we investigated the putative association between common nonsynonymous PON1 polymorphisms and the risk of developing astrocytoma and meningioma.     

Long-term effects of graduated compression stockings on cardiorespiratory performance

The use of graduated compression stockings (GCS) in sport has been increasing in the last years due to their potential positive effects for athletes. However, there is little evidence to support whether these types of garments actually improve cardiorespiratory performance. The aim of this study was to examine the cardiorespiratory responses of GCS during running after three weeks of regular use. Twenty recreational runners performed three tests on different days: test 1) – a 5-min maximal effort run in order to determine the participants’ maximal aerobic speed; and tests 2) and 3) – a fatigue running test of 30 minutes at 80% of their maximal aerobic speed with either GCS or PLACEBO stockings at random. Cardiorespiratory parameters (minute ventilation, heart rate, relative oxygen consumption, relative carbon dioxide production, ventilatory equivalents for oxygen and carbon dioxide, and oxygen pulse) were measured. Before each test in the laboratory, the participants trained with the randomly assigned stockings (GCS or PLACEBO) for three weeks. No significant differences between GCS and PLACEBO were found in any of the cardiorespiratory parameters. In conclusion, the present study provides evidence that running with GCS for three weeks does not influence cardiorespiratory parameters in recreational runners.     

Functional architecture of the inner pore of a voltage-gated Ca2+ channel

The inner pore of voltage-gated Ca2+ channels (VGCCs) is functionally important, but little is known about the architecture of this region. In K+ channels, this part of the pore is formed by the S6/M2 transmembrane segments from four symmetrically arranged subunits. The Ca2+ channel pore, however, is formed by four asymmetric domains of the same (alpha1) subunit. Here we investigated the architecture of the inner pore of P/Q-type Ca2+ channels using the substituted-cysteine accessibility method. Many positions in the S6 segments of all four repeats of the alpha1 subunit (Ca(v)2.1) were modified by internal methanethiosulfonate ethyltrimethylammonium (MTSET). However, the pattern of modification does not fit any known sequence alignment with K+ channels. In IIS6, five consecutive positions showed clear modification, suggesting a likely aqueous crevice and a loose packing between S6 and S5 segments, a notion further supported by the observation that some S5 positions were also accessible to internal MTSET. These results indicate that the inner pore of VGCCs is indeed formed by the S6 segments but is different from that of K+ channels. Interestingly some residues in IIIS6 and IVS6 whose mutations in L-type Ca2+ channels affect the binding of dihydropyridines and phenylalkylamines and are thought to face the pore appeared not to react with internal MTSET. Probing with qBBr, a rigid thiol-reactive agent with a dimension of 12 angstroms x 10 angstroms x 6 angstroms suggests that the inner pore can open to >10 angstroms. This work provides an impetus for future studies on ion permeation, gating, and drug binding of VGCCs.