240 research outputs found
Analysis of AFLP Markers for Screening Resistance to Common Bean Roots Rot (Pythium spp.)
Aims: To investigate AFLPs for suitability as potential markers for identification of sources of
Pythium resistance in bean genotypes preferred by poor small holder farmers.
Place and Duration of Study: Department of biological sciences Masinde Muliro University of
Science and Technology, Kenya and Bangor University, North Wales, United Kingdom, between
September 2010 and December 2012.
Methodology: 45 common bean accessions comprising 35 seed samples collected from farmers,
market centers, as well as seed stockists and ten common bean lines generated from a
conventional breeding program with differential resistance to the pathogen Pythium were subjected
to AFLP analysis. Genetic characterization using cluster and principal component analysis were
conducted to determine segregating patterns of bean accessions in relation to tolerant and
Original Research Article
Maryrose et al.; AJEA, 5(4): 374-391, 2015; Article no.AJEA.2015.039
375
susceptible bean lines. Average genetic distances were calculated and similarity coefficients
subjected to unweighted pair group method of arithmetic averages to generate dendograms.
Results: Two informative AFLP primer combinations yielded 194 polymorphic loci. Genetic distance
of bean samples from KARI Kakamega had 56 to 414 base pairs with a variability index of 0.63 to
0.90. Combined analysis of bean accessions from KARI breeding program and market class
common bean samples revealed a variability index range of 0.62 to 0.90 with 56 to 420 base pairs.
PCA contributed about 51.58% on the genetic variation. Cluster analysis of the 10 KARI-Kakamega
bean lines revealed that resistant bean varieties were genetically different from the susceptible
bean varieties. The dendogram generated revealed four sub-groups and with the exception of Alulu,
a mildly resistant cultivar, that segregated alongside resistant cultivars, resistant varieties clustered
differently from susceptible cultivars. However, screening with farmers’ germplasm produced a
dendogram that revealed a mixture of distinct and relatively non-distinct categorization with regard
to resistance. Only resistant cultivars AN1062, R2075, R719 and R1946 and susceptible cultivars
GLP2 and GLP585 clustered together as expected. The others segregated randomly alongside the
farmers’ germplasm. Resistant varieties AND1062, R2075, R719, R1946 and SCAM80 were more
genetically related to marketable class of beans. R1946 R719, R2075 and AND1062 are closely
related genetically compared to Mw001, KK15, Alulu and GLP2.
Conclusion: AFLP is a relatively informative technique that has a great potential of delineating
susceptible and resistant Pythium root rot dry bean varieties, and can be used as a preliminary
guide to carry out further analysis. It is notable that the AFLP markers used were not able to clearly
distinguish all the cultivars comprehensively and should not be used alone in determining resistance
levels. The information generated in this study will contribute to the propagation of acceptable
market class bean lines with resistance to Pythium root rot for improved livelihood and increased
food securit
Genetic Diversity of Dry Bean (Phaseolus vulgaris L.) Accessions of Kenya Using SSR Markers
Aims: To determine the genetic diversity existing within the Kenyan dry bean using SSR markers.
Place and Duration of Study: This study was conducted in Western Kenya and Bangor
University, North Wales, between September 2010 and December 2012.Methodology: Thirty five (35) marketable dry bean samples collected from farmers, market centers as well as seed stockists were subjected to SSR analysis. Data generated was subjected to analysis with the GenAlEx 6.4 software assuming Hardy-Weinberg equilibrium to determine gene diversity index, number of polymorphic loci and alleles, genetic distances, analysis of molecular Original Research Article
Maryrose et al.; AJEA, 5(4): 306-319, 2015; Article no.AJEA.2015.030
307
variance (AMOVA) and principal components analysis (PCA). NYTS-pc 2.1 software was used to
construct an unweighted pair group method arithmetic averages (UPGMA) dendogram using the
generated similarity coefficients.
Results: Of the 7 SSR primers tested, 5 SSR primers were found to be polymorphic and used to
screen the bean samples. The 5 primer combinations generated 49 polymorphic bands in 35
samples. Analysis of molecular variance accredited 8% of the disparity to diversity among the
populations while the majority of the diversity (92%), resided within populations. The gene diversity
index ranged from 0.1267 in the market population to 0.2377 in the Western province population.
The highlands of Eastern province had a gene diversity index of 0.1475 while the dry lands had
0.1991. Cluster analysis segregated the bean samples into 9 clusters.
Conclusion: There exists considerable variation in the dry bean of Kenya that is narrowing. There
is need to intensify efforts to broaden the bean variation for sustainability. The population genetics
of dry beans of Kenya are a possible guide to future bean breeding and germplasm management in
Kenya.
Keywords: SSRs; Phaseolus vulgaris; dry bean; germplasm characterization; and genetic variatio
Motor modules during adaptation to walking in a powered ankle exoskeleton
Abstract
Background
Modules of muscle recruitment can be extracted from electromyography (EMG) during motions, such as walking, running, and swimming, to identify key features of muscle coordination. These features may provide insight into gait adaptation as a result of powered assistance. The aim of this study was to investigate the changes (module size, module timing and weighting patterns) of surface EMG data during assisted and unassisted walking in an powered, myoelectric, ankle-foot orthosis (ankle exoskeleton).
Methods
Eight healthy subjects wore bilateral ankle exoskeletons and walked at 1.2 m/s on a treadmill. In three training sessions, subjects walked for 40 min in two conditions: unpowered (10 min) and powered (30 min). During each session, we extracted modules of muscle recruitment via nonnegative matrix factorization (NNMF) from the surface EMG signals of ten muscles in the lower limb. We evaluated reconstruction quality for each muscle individually using R2 and normalized root mean squared error (NRMSE). We hypothesized that the number of modules needed to reconstruct muscle data would be the same between conditions and that there would be greater similarity in module timings than weightings.
Results
Across subjects, we found that six modules were sufficient to reconstruct the muscle data for both conditions, suggesting that the number of modules was preserved. The similarity of module timings and weightings between conditions was greater then random chance, indicating that muscle coordination was also preserved. Motor adaptation during walking in the exoskeleton was dominated by changes in the module timings rather than module weightings. The segment number and the session number were significant fixed effects in a linear mixed-effect model for the increase in R2 with time.
Conclusions
Our results show that subjects walking in a exoskeleton preserved the number of modules and the coordination of muscles within the modules across conditions. Training (motor adaptation within the session and motor skill consolidation across sessions) led to improved consistency of the muscle patterns. Subjects adapted primarily by changing the timing of their muscle patterns rather than the weightings of muscles in the modules. The results of this study give new insight into strategies for muscle recruitment during adaptation to a powered ankle exoskeleton.https://deepblue.lib.umich.edu/bitstream/2027.42/140718/1/12984_2017_Article_343.pd
Geochemical, metagenomic and metaproteomic insights into trace metal utilization by methane-oxidizing microbial consortia in sulphidic marine sediments
Microbes have obligate requirements for trace metals in metalloenzymes that catalyse important biogeochemical reactions. In anoxic methane- and sulphide-rich environments, microbes may have unique adaptations for metal acquisition and utilization because of decreased bioavailability as a result of metal sulphide precipitation. However, micronutrient cycling is largely unexplored in cold (≤ 10°C) and sulphidic (> 1 mM ΣH_(2)S) deep-sea methane seep ecosystems. We investigated trace metal geochemistry and microbial metal utilization in methane seeps offshore Oregon and California, USA, and report dissolved concentrations of nickel (0.5–270 nM), cobalt (0.5–6 nM), molybdenum (10–5600 nM) and tungsten (0.3–8 nM) in Hydrate Ridge sediment porewaters. Despite low levels of cobalt and tungsten, metagenomic and metaproteomic data suggest that microbial consortia catalysing anaerobic oxidation of methane (AOM) utilize both scarce micronutrients in addition to nickel and molybdenum. Genetic machinery for cobalt-containing vitamin B_(12) biosynthesis was present in both anaerobic methanotrophic archaea (ANME) and sulphate-reducing bacteria. Proteins affiliated with the tungsten-containing form of formylmethanofuran dehydrogenase were expressed in ANME from two seep ecosystems, the first evidence for expression of a tungstoenzyme in psychrophilic microorganisms. Overall, our data suggest that AOM consortia use specialized biochemical strategies to overcome the challenges of metal availability in sulphidic environments
KASP™ based markers reveal a population sub-structure in temperate rice (Oryza sativa L.) germplasm and local landraces grown in the Kashmir valley, north-western Himalayas
Radiative Corrections to the Inflaton Potential as an Explanation of Suppressed Large Scale Power in Density Perturbations and the Cosmic Microwave Background
The Wilkinson Microwave Anisotropy Probe microwave background data suggest
that the primordial spectrum of scalar curvature fluctuations is suppressed at
small wavenumbers. We propose a UV/IR mixing effect in small-field inflationary
models that can explain the observable deviation in WMAP data from the
concordance model. Specifically, in inflationary models where the inflaton
couples to an asymptotically free gauge theory, the radiative corrections to
the effective inflaton potential can be anomalously large. This occurs for
small values of the inflaton field which are of the order of the gauge theory
strong coupling scale. Radiative corrections cause the inflaton potential to
blow up at small values of the inflaton field. As a result, these corrections
can violate the slow-roll condition at the initial stage of the inflation and
suppress the production of scalar density perturbations.Comment: 20 pages, 2 figures, v2: refs added, v3: JCAP versio
Prevalent Multimorbidity Combinations Among Middle-Aged and Older Adults Seen in Community Health Centers
BACKGROUND: Multimorbidity (≥ 2 chronic diseases) is associated with greater disability and higher treatment burden, as well as difficulty coordinating self-management tasks for adults with complex multimorbidity patterns. Comparatively little work has focused on assessing multimorbidity patterns among patients seeking care in community health centers (CHCs).
OBJECTIVE: To identify and characterize prevalent multimorbidity patterns in a multi-state network of CHCs over a 5-year period.
DESIGN: A cohort study of the 2014-2019 ADVANCE multi-state CHC clinical data network. We identified the most prevalent multimorbidity combination patterns and assessed the frequency of patterns throughout a 5-year period as well as the demographic characteristics of patient panels by prevalent patterns.
PARTICIPANTS: The study included data from 838,642 patients aged ≥ 45 years who were seen in 337 CHCs across 22 states between 2014 and 2019.
MAIN MEASURES: Prevalent multimorbidity patterns of somatic, mental health, and mental-somatic combinations of 22 chronic diseases based on the U.S. Department of Health and Human Services Multiple Chronic Conditions framework: anxiety, arthritis, asthma, autism, cancer, cardiac arrhythmia, chronic kidney disease (CKD), chronic obstructive pulmonary disease (COPD), congestive heart failure, coronary artery disease, dementia, depression, diabetes, hepatitis, human immunodeficiency virus (HIV), hyperlipidemia, hypertension, osteoporosis, post-traumatic stress disorder (PTSD), schizophrenia, substance use disorder, and stroke.
KEY RESULTS: Multimorbidity is common among middle-aged and older patients seen in CHCs: 40% have somatic, 6% have mental health, and 24% have mental-somatic multimorbidity patterns. The most frequently occurring pattern across all years is hyperlipidemia-hypertension. The three most frequent patterns are various iterations of hyperlipidemia, hypertension, and diabetes and are consistent in rank of occurrence across all years. CKD-hyperlipidemia-hypertension and anxiety-depression are both more frequent in later study years.
CONCLUSIONS: CHCs are increasingly seeing more complex multimorbidity patterns over time; these most often involve mental health morbidity and advanced cardiometabolic-renal morbidity
Social recovery therapy: a treatment manual
Social Recovery Therapy is an individual psychosocial therapy developed for people with psychosis. The therapy aims to improve social recovery through increasing the amount of time individuals spend in meaningful structured activity. Social Recovery Therapy draws on our model of social disability arising as functional patterns of withdrawal in response to early socio-emotional difficulties and compounded by low hopefulness, self-agency and motivation. The core components of Social Recovery Therapy include using an assertive outreach approach to promote a positive therapeutic relationship, with the focus of the intervention on using active behavioural work conducted outside the clinical room and promoting hope, values, meaning, and positive schema. The therapy draws on traditional Cognitive Behavioural Therapy techniques but differs with respect to the increased use of behavioural and multi-systemic work, the focus on the development of hopefulness and positive self, and the inclusion of elements of case management and supported employment. Our treatment trials provide evidence for the therapy leading to clinically meaningful increases in structured activity for individuals experiencing first episode and longer-term psychosis. In this paper, we present the core intervention components with examples in order to facilitate evaluation and implementation of the approach
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