Risk factors for falls in older adults in a South African Urban Community

Background: Studies on falls in older adults have mainly been conducted in high income countries. Scant, if any, information exists on risk factors for falls in the older population of sub-Saharan African countries. Methods: A cross-sectional survey and a 12-month follow-up study were conducted to determine risk factors for falls in a representative multi-ethnic sample of 837 randomly selected ambulant community-dwelling subjects aged ≥65 years in three suburbs of Cape Town, South Africa. Logistic regression models were fitted to determine the association between (1) falls and (2) recurrent falls occurring during follow-up and their potential socio-demographic, self-reported medical conditions and physical assessment predictors. Results: Prevalence rates of 26.4 % for falls and 11 % for recurrent falls at baseline and 21.9 % for falls and 6.3 % for recurrent falls during follow-up. In both prospective analyses of falls and recurrent falls, history of previous falls, dizziness/vertigo, ethnicity (white or mixed ancestry vs black African) were significant predictors. However, poor cognitive score was a significant predictor in the falls analysis, and marital status (unmarried vs married) and increased time to perform the timed Up and Go test in the recurrent fall analysis but not in both. Other than the timed Up and Go test in recurrent falls analysis, physical assessment test outcomes were not significant predictors of falls. Conclusion: Our study provides simple criteria based on demographic characteristics, medical and physical assessments to identify older persons at increased risk of falls. History taking remains an important part of medical practice in the determination of a risk of falls in older patients. Physical assessment using tools validated in developed country populations may not produce results needed to predict a risk of falls in a different setting

The effect of tropical sorghum conversion and inbred development on genome diversity as revealed by high-resolution genotyping

Graphical genotypes have been generated for a set of sorghum [Sorghum bicolor (L.) Moench] germplasm, which includes selected public inbreds, germplasm from the world collection, and ancestral lines central to the early breeding efforts of sorghum. We have focused our present examination on sorghum chromosome SBI-06, which encodes mal and dw(2), two genes critical to sorghum improvement dating to the original introduction of tropical sorghums into the United States. Utilizing the pedigree relationship between sorghum cultivars, the patterns of genetic variation were detailed within segmental chromosomal blocks of SBI-06. Segmental genomic blocks were traced back through multiple generations of a pedigree, often back to founder tropical accessions. The graphical genotypes reveal genomic signatures of historical breeding decisions, especially evidence of directional selection during the conversion of tropical accessions to temperate adaptation. This information is central to our efforts to understand those crop improvement processes that have shaped the genomic diversity of elite sorghum cultivars

The effect of tropical sorghum conversion and inbred development on genome diversity as revealed by high-resolution genotyping

Graphical genotypes have been generated for a set of sorghum [Sorghum bicolor (L.) Moench] germplasm, which includes selected public inbreds, germplasm from the world collection, and ancestral lines central to the early breeding efforts of sorghum. We have focused our present examination on sorghum chromosome SBI-06, which encodes ma1 and dw2, two genes critical to sorghum improvement dating to the original introduction of tropical sorghums into the United States. Utilizing the pedigree relationship between sorghum cultivars, the patterns of genetic variation were detailed within segmental chromosomal blocks of SBI-06. Segmental genomic blocks were traced back through multiple generations of a pedigree, often back to founder tropical accessions. The graphical genotypes reveal genomic signatures of historical breeding decisions, especially evidence of directional selection during the conversion of tropical accessions to temperate adaptation. This information is central to our efforts to understand those crop improvement processes that have shaped the genomic diversity of elite sorghum cultivars

CC: Intraspecific variation of recombination rate in maize. Genome Biol

Abstract Background: In sexually reproducing organisms, meiotic crossovers ensure the proper segregation of chromosomes and contribute to genetic diversity by shuffling allelic combinations. Such genetic reassortment is exploited in breeding to combine favorable alleles, and in genetic research to identify genetic factors underlying traits of interest via linkage or association-based approaches. Crossover numbers and distributions along chromosomes vary between species, but little is known about their intraspecies variation

Intraspecific variation of recombination rate in maize

Abstract Background In sexually reproducing organisms, meiotic crossovers ensure the proper segregation of chromosomes and contribute to genetic diversity by shuffling allelic combinations. Such genetic reassortment is exploited in breeding to combine favorable alleles, and in genetic research to identify genetic factors underlying traits of interest via linkage or association-based approaches. Crossover numbers and distributions along chromosomes vary between species, but little is known about their intraspecies variation. Results Here, we report on the variation of recombination rates between 22 European maize inbred lines that belong to the Dent and Flint gene pools. We genotype 23 doubled-haploid populations derived from crosses between these lines with a 50 k-SNP array and construct high-density genetic maps, showing good correspondence with the maize B73 genome sequence assembly. By aligning each genetic map to the B73 sequence, we obtain the recombination rates along chromosomes specific to each population. We identify significant differences in recombination rates at the genome-wide, chromosome, and intrachromosomal levels between populations, as well as significant variation for genome-wide recombination rates among maize lines. Crossover interference analysis using a two-pathway modeling framework reveals a negative association between recombination rate and interference strength. Conclusions To our knowledge, the present work provides the most comprehensive study on intraspecific variation of recombination rates and crossover interference strength in eukaryotes. Differences found in recombination rates will allow for selection of high or low recombining lines in crossing programs. Our methodology should pave the way for precise identification of genes controlling recombination rates in maize and other organisms.Results have been achieved in the framework of the Transnational (Germany, France, Spain) Cooperation within the PLANT-KBBE Initiative Cornfed, additionally supported by the project AMAIZING. The work was financed by grants from Agence Nationale de la Recherche ('ANR') to AC, MF, MM, and PF, grants from the Ministry of Science and Innovation (Ministerio de Ciencia e Innovación ('MICINN')) to JMG and PR, and grants from the Federal Ministry of Education and Research (Bundesministerium für Bildung und Forschung, 'BMBF') to TA, AEM, MO, and CCS.Peer Reviewe

Phenotypic Characterization of Quality Protein Maize Endosperm Modification and Amino Acid Contents in a Segregating Recombinant Inbred Population

The protein quality of maize (Zea mays L.) can be improved by replacing normal Opaque2alleles with nonfunctional recessive alleles (o2). Homozygous o2 kernels have increased levels of lysine and tryptophan. Unfortunately, the associated soft texture of the o2 kernels causes poor yield and susceptibility to diseases and insects. Breeding has resulted in the development of o2 genotypes with improved endosperm hardness; such genotypes are referred to as quality protein maize (QPM). Quality protein maize germplasm is utilized in breeding programs worldwide and has been competitive in yield trials. To understand the genetics of endosperm modification, a population of 146 recombinant inbred lines (S5 to S7) derived from a cross between the o2 inbred B73o2 and the QPM inbred CML161 was evaluated in two Texas locations from 2004 to 2006. The endosperm traits texture, opacity, and vitreousness were highly affected by inbred line genotype, were highly correlated with each other, and exhibited high broad-sense heritability. Relative content of the essential amino acids lysine, tryptophan, and methionine were also highly affected by the inbred line genotype, and exhibited high broad-sense heritability. Negative correlation was observed between endosperm texture traits and amino acid contents. Favorable responses to selection can be expected for both endosperm texture modification and relative content of the essential amino acids if they are efficiently monitored.This article is published as Gutierrez-Rojas, Andres, M. Paul Scott, Otto R. Leyva, Monica Menz, and Javier Betrán. "Phenotypic characterization of quality protein maize endosperm modification and amino acid contents in a segregating recombinant inbred population." Crop science 48, no. 5 (2008): 1714-1722, doi: 10.2135/cropsci2007.08.0429.</p