Genetic diversity among proso millet (Panicum miliaceum) biotypes assessed by AFLP technique

The Amplified Fragment Length Polymorphism (AFLP) technique was used to access genetic diversity between three domestic and nine wild proso millet biotypes from the United States and Canada. Eight primer combinations detected 39 polymorphic DNA fragments, with the genetic distance estimates among biotypes ranging from 0.02 to 0.04. Colorado-Weld County black seeded and Wyoming-Platte County were the most distinct biotypes according to the dissimilarity level. A UPGMA cluster analysis revealed two distinct groups of proso millet without any geographic association. Six weed biotypes exhibiting some characters of cultivated plants were grouped together with domesticated biotypes of proso millet while the three typical wild phenotypes were clearly clustered into another group according to AFLP markers.

Genetic interactions involving major genes at the dwarf locus in egg-type chickens

Three egg-type stocks segregating dwarf (dw) and bantam (dwB) genes in female progeny were produced from the same 18 heterozygous (dwB/dw) sires used to inseminate dams of three different genotypes: normal (dw+), dwarf (dw) and bantam (dwB) dams. The heritability of 8-week body weight estimated from full-sibs of the same phenotype of progeny was 0.40, and that estimated from paternal half-sibs of the same phenotype (dwarf or bantam), and from the same genotype of dam was 0.38. Therefore, maternal and non-additive effects within genotypic classes of dam made little contribution to the genetic variance for 8-week body weight among their progeny. The interaction of sires (S) with genotypes (dw+, dw and dwB) of dam (G) was significant at the 5% level. This indicates that the rankings of the sires within each one of the three genotypes of dam were not the same, probably due to non-additive genetic variation among genotypes of dams. The evidence indicated that in general the genes from individual sires combined differently with each type of dam (G). Those genes which combined well with the genes from normal (dw+) dams combined poorly with both the genes from the dwarf (dw) and the genes from the bantam (dwB) dams. The interaction of sires (S) with phenotypes (dwarf and bantam) of progeny (P) was significant at the 10% level. The results indicated a probable gene x genotype interaction for 8-week weight between genes at the dwarf locus (dw and dwB) and the background genotype (single and/or polygenes). The correlation among paternal half-sibs was influenced more by the S x G than by the S x P interaction, but the effects tended to be cumulative

Use of canonical variates in genetic divergence studies

Exact correlation coefficients between a canonical variate and measured traits were derived to evaluate genetic divergence among varieties. This method allows the plant breeder to determine which traits contribute significantly to genetic divergence and, also, to identify the most important among them. An example is presented, related to a trial where 28 varieties of maize were evaluated for two traits

Genetic engineering of baker's and wine yeasts using formaldehyde hyperresistance-mediating plasmids

Yeast multi-copy vectors carrying the formaldehyde-resistance marker gene SFA have proved to be a valuable tool for research on industrially used strains of Saccharomyces cerevisiae. The genetics of these strains is often poorly understood, and for various reasons it is not possible to simply subject these strains to protocols of genetic engineering that have been established for laboratory strains of S. cerevisiae. We tested our vectors and protocols using 10 randomly picked baker's and wine yeasts all of which could be transformed by a simple protocol with vectors conferring hyperresistance to formaldehyde. The application of formaldehyde as a selecting agent also offers the advantage of its biodegradation to CO2 during fermentation, i.e., the selecting agent will be consumed and therefore its removal during down-stream processing is not necessary. Thus, this vector provides an expression system which is simple to apply and inexpensive to use

Use of fluorescent probes to follow membrane traffic in nerve terminals

Optical tracers in conjunction with fluorescence microscopy have become widely used to follow the movement of synaptic vesicles in nerve terminals. The present review discusses the use of these optical methods to understand the regulation of exocytosis and endocytosis of synaptic vesicles. The maintenance of neurotransmission depends on the constant recycling of synaptic vesicles and important insights have been gained by visualization of vesicles with the vital dye FM1-43. A number of questions related to the control of recycling of synaptic vesicles by prolonged stimulation and the role of calcium to control membrane internalization are now being addressed. It is expected that optical monitoring of presynaptic activity coupled to appropriate genetic models will contribute to the understanding of membrane traffic in synaptic terminals.

Genetic and environmental influences on blood pressure and physical activity: a study of nuclear families from Muzambinho, Brazil

Blood pressure (BP) and physical activity (PA) levels are inversely associated. Since genetic factors account for the observed variation in each of these traits, it is possible that part of their association may be related to common genetic and/or environmental influences. Thus, this study was designed to estimate the genetic and environmental correlations of BP and PA phenotypes in nuclear families from Muzambinho, Brazil. Families including 236 offspring (6 to 24 years) and their 82 fathers and 122 mothers (24 to 65 years) were evaluated. BP was measured, and total PA (TPA) was assessed by an interview (commuting, occupational, leisure time, and school time PA). Quantitative genetic modeling was used to estimate maximal heritability (h²), and genetic and environmental correlations. Heritability was significant for all phenotypes (systolic BP: h² = 0.37 ± 0.10, P < 0.05; diastolic BP: h² = 0.39 ± 0.09, P < 0.05; TPA: h² = 0.24 ± 0.09, P < 0.05). Significant genetic (r g) and environmental (r e) correlations were detected between systolic and diastolic BP (r g = 0.67 ± 0.12 and r e = 0.48 ± 0.08, P < 0.05). Genetic correlations between BP and TPA were not significant, while a tendency to an environmental cross-trait correlation was found between diastolic BP and TPA (r e = -0.18 ± 0.09, P = 0.057). In conclusion, BP and PA are under genetic influences. Systolic and diastolic BP share common genes and environmental influences. Diastolic BP and TPA are probably under similar environmental influences.

An artificial neural network model for prediction of quality characteristics of apples during convective dehydration

In this study, the effects of hot-air drying conditions on color, water holding capacity, and total phenolic content of dried apple were investigated using artificial neural network as an intelligent modeling system. After that, a genetic algorithm was used to optimize the drying conditions. Apples were dried at different temperatures (40, 60, and 80 °C) and at three air flow-rates (0.5, 1, and 1.5 m/s). Applying the leave-one-out cross validation methodology, simulated and experimental data were in good agreement presenting an error < 2.4 %. Quality index optimal values were found at 62.9 °C and 1.0 m/s using genetic algorithm.