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A clear understanding of the genetic mechanism that controls the expression of the agronomic traits is imperative to define appropriate selection methods in bean breeding. The objective of this study was to assess the level of variability and genetic gain within iron and zinc biofortified common bean genotypes in eastern Democratic Republic of Congo. A field study was conducted involving 164 Fe and Zn dense bean genotypes and five local (non-biofortified) varieties. Data was collected on the number of days to flowering, number of days to 75 and 90% of maturity, number of pods per plant and seeds per pod, total grain yield and 100 seed-weight. There were significant differences among genotypes for all the traits monitored except for number of pods per plant and grain yield. The yield for genotypes RW298, BF08-16-36A, BF08-1-77, RWV2359 and MV-14 was more than 2000 kg ha-1. These records make these genotypes the most competitive for this specific trait. The variance components showed moderate broad-sense heritability for the number of days to flowering and low for all the other parameters. Also, genotypic coefficient of variation was moderate only for grain yield but low for all other characters. The genetic gain was low (<10%) for all the traits, suggesting a non-additive gene action controlling the traits considering the study genotypes. Clustering showed that genotypes could be grouped into four important clusters (Cluster 1 = 49 genotypes, Cluster 2 = 30 genotypes, Cluster 3 = 42 genotypes and Cluster 4 = 48 genotypes). It is recommended that selections should be effected within the Cluster 2 (blue part of the dendrogram) which comprised the most promising genotypes for grain yield or to subject the study genotypes to heterosis breeding method. [ABSTRACT FROM AUTHOR]

This study examined the heritability and genetic correlations of muscle proximate composition (including crude lipid, protein, moisture, and ash) in the Chinese mitten crab, Eriocheir sinensis. The results showed that the heritability of proximate composition traits, was 0.12 ± 0.07 for moisture, 0.04 ± 0.04 for crude fat, 0.07 ± 0.05 for crude protein and 0.03 ± 0.04 for ash, respectively. A positive genetic correlation (0.88) was observed between crude lipid and protein, whereas a negative correlation existed between crude lipid and moisture (−0.74), indicating that crude lipid content could be improved by moisture selection indirectly. The muscle-moisture trait has the highest heritability, and is the easiest parameter to measure among the four proximate composition traits. Our results provide fundamental information for the development of improved genetic-programmes utilizing quality traits of E. sinensis. [ABSTRACT FROM AUTHOR]

L’opération la plus importante dans un schéma d’amélioration génétique est le contrôle des performances qui doit être simple, fiable et peu coûteux. L’étude vise à simuler les méthodes alternatives de simplification de l'enregistrement des poids à âge type pour calculer les gains moyens quotidiens (GMQ) des chevreaux locaux et évaluer l'impact de leur utilisation d'un point de vue génétique pour établir la base d’une amélioration future. Un total de 945 chevreaux (531 mâles et 414 femelles), issus de 19 boucs et 285 chèvres, nés entre 1998 et 2014, ont été utilisé dans cette étude. Les paramètres génétiques ont été estimés pour cinq phénotypes : GMQ (1 -30), GMQ (30-60), GMQ (60-90), GMQ (90-120), GMQ (120-150). L’âge de la mère à la mise bas, l’année et mois de naissance et le sexe du chevreau ont été inclus en tant que facteurs fixes, dans le modèle mixte. La simplification à une et deux semaines a conduit à des héritabilités directes et maternelles pour les différents gains moyens quotidiens, similaires à celles obtenues par l'enregistrement de croissance standard. Une réduction du nombre de contrôles à une et deux semaines pourrait donc être adoptée.

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Garlic (Allium sativum) has for centuries been valued by humans for food, culinary and medicinal purposes world over. The objective of this study was to investigate genetic variability among garlic accessions for yield, yield related and phenology traits in Ethiopia. A field study was conducted at the DebreZeit Agricultural Research Center during 2012, using 49 garlic accessions from the highlands of North Shewa, East and West Arsi, Arsi, Bale and Sidama zones, which are among the major garlic producing areas in Ethiopia. The experiment was arranged in a 7x7 simple Lattice design, with two replications. Accession were highly significant (P < 0.01) for days to maturity, leaf number per plant, neck diameter, yield per plant, biological yield per plant, dry weight above ground, bulb dry weight, dry weight underground, clove number per bulb, and clove weight per bulb. Heritability estimates ranged from 82.48% for clove number, to 6.46% harvest index. High heritability, combined with high genetic advance (as per cent of mean) observed for mean clove number, yield per plant, biological yield per plant and clove weight per plant showed that these characters were controlled by additive gene effects. Thus phenotypic selection for these characters would likely be effective in variety selection and development. Bulb yield per plant had positive and highly significant genotypic and phenotypic correlations, with all characters, except plant height and harvest index. Path analysis at phenotypic level revealed that biological yield and bulb dry weight contributed major positive direct effects to bulb yield per plant. These traits showed positive and highly significant genotypic correlations with bulb yield except harvest index. [ABSTRACT FROM AUTHOR]

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Copyright of Canadian Journal of Animal Science is the property of Canadian Science Publishing and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Canadian Journal of Plant Science is the property of Canadian Science Publishing and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Safflower (Carthamus tinctorius L.) is of potential interest to agriculture due to mainly variability of fatty acid composition of seeds oil. The purpose of this study was to evaluate various exotic genotypes of safflower for agronomic traits, components of seed yield and fatty acid content. For this purpose, plant height (cm), number of first, second and third branches/plant, seed yield/plant (g), thousandseed weight (g), oil content (%), and composition of fatty acid were investigated. Stepwise multiple regression analysis was used to develop fitted equation to predicate seed yield/plant. Analysis of variance of agronomic traits showed high differences among genotypes. Although the safflower oil genotype K2 had the highest oil seed content (42.8%), K13 obtained the highest percentage of monounsaturated fatty acids (MUFA). Highest oleic type of safflower oil has been found in K13 and K26, which can be used as a source oil quality for plant breeding. Heritability as broad sense was high and ranged from 82% in number of secondary branches (NSB) and number of third branches (NTHB) to 99% in seed index (1000 seeds weight) and oil content. High genetic advance was found in plant height (PH), seed yield/plant (SYP) and 1000-seed weight, estimated at 43.41 cm, 21.34 g and 17.62 g, respectively. Stepwise multiple regression analysis indicated that, 99.2% of the total variation in seed yield/plant could be explained by variation in yield of secondary (YSB) branches, yield of first branches (YFB), yield of third branches (YTHB), plant height (PH) and spiny as dummy variable. 23.56% of the total variation in seed oil percent could be explained by variation in yield of first branches (YFB), seed index and spiny as dummy variable. The information detected here may be a useful tool for the selection of parents in safflower breeding program. [ABSTRACT FROM AUTHOR]

Selection of superior genotypes and measuring heritability are some of the basic objectives of plant breeding. For this purpose, plant breeders grow crops across environments. Understanding the pattern of response across environments is an integral component of selection of superior and stable genotypes. The objective of this study was to improve selection strategies in barley breeding of Ethiopia through modeling spatial field trend. A set of multi-environment trials (MET) data from the national variety trial series conducted over four years, was taken from the Ethiopian Barley Breeding Programme, spanning stages from early generation to national variety trial testing for yield, was used in this study. The trials were analysed in a linear mixed model framework. Then, fitting a one-stage model for MET data, including a correlated spatial process for field trend within each trial, and combining a factor analytic (FA) model for genotype by environment interaction was conducted. The genetic correlations from this MET analysis were then used to cluster the environments based on their similarity. Performance of genotypes across these environmental clusters indicate broad (Bekoji-2005 and Bekoji-2004) and specific adaptation (Sgonder-2007 and Sgonder-2006) of genotype to certain types of environments. In addition, analysis of this historical MET data shed light on how breeding programme design can be improved to capture responses across the target population of environments, as it can inform the adequacy of the current number of barley grown areas in Ethiopia and the improvement in measuring heritability. [ABSTRACT FROM AUTHOR]

The African stem borer (Busseola fusca [Fuller]) is an important insect pest of cereals, mainly maize, sorghum and millets. The pest causes up to 80% reduction in grain yield, depending on the pest population in the field, cultivar and the management practices employed. This reduction in yield translates into food insecurity, especially in semi-arid lands (ASALs) where sorghum is cultivated by small holder farmers. This study investigated the inheritance of resistance traits to the African stem borers in grain sorghum in Kenya. The experimental material consisted of seventeen sorghum lines with varying levels of resistance to the African stem borer. The mating design employed was North Calorina Design 2, where 15 sorghum lines were used as females on two males. The crosses were evaluated in two seasons at University of Embu farm in 2011/2012 short and long seasons replicated twice. Artificial infestation with African stem borer neonates was done 30 days after planting using a camel brush. Data collected included stem borer damage and agro-morphological traits. Genetic analyses were performed using a line x tester method using Genstat statistical software. It was found that both additive and non-additive gene effects were important in conditioning resistance traits to the African stem borer. This implies that expression of high leaf glossiness, plant vigour and bloom waxiness in F1 hybrids is conditioned by additive genes and these traits can be used as morphological markers to select for resistance to the borer in sorghum. ICSB 464 x ICSB 473 was the best combiner for stem borer resistance and grain yield. Parents ICSA 464, ICSB 464 and ICSB 474, were among the good combiners for resistance to the stem borer. These parents can be utilised in developing superior sorghum hybrids resistant to the insect pest. [ABSTRACT FROM AUTHOR]

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Bottle gourd [Lagenaria siceraria (Molina) Standley] is an important tropical specie characterised by a wide diversity and a low yield, mainly due to no selection for improved varieties. Selection for a particular trait depends on the relative importance of genetic and nongenetic factors influencing the expression of phenotypic differences among crop population. The objective of this study was to examine the genetics basis of seed yield and yield components, by crossing oleaginous type and calabash-type of bottle gourd [Lagenaria siceraria (Molina) Standley]. The parental lines (P1 and P2), with the respective hybrids F1 and F2 generations, were grown in two contrasted locations in terms of pedoclimatic conditions. Results showed no significant difference between the two locations for studies traits (P=0.06). For seed yield per plant, 100-seed weight per fruit, and number of seeds per fruit, a positive hypothetical heterosis was observed when calabash type was a maternal parent. Negative real heterosis was observed in all studied traits. For all traits, the genetic variance was higher than the environmental variance in the most of the crosses, implying greatest genes action in the expression of studies traits. Heritability was medium for fruit weight (mean, 42.12%) and seed number per fruit (mean, 47.36%). But for 100-seed weight (mean, 61.00%) and seed yield per plant (mean, 53.28%) high heritability were observed. The minimum number of genes that controlled the expression of 100-seed weight (0.58), seed yield per plant (1.58) and number of seeds per plant (0.98) was low (close to 1). These observations suggest that distinct genotypes for interest characters would be fixed by using a small number of selfing generations (F3 to F4) in West African bottle gourd. [ABSTRACT FROM AUTHOR]

Copyright of Canadian Journal of Plant Science is the property of Canadian Science Publishing and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The number one goal of most rice improvement programmes around the world is breeding for high potential to take care of the increasing consumption of rice. The objective of this experiment was to study the inheritance of yield and yield components and to estimate the heritabilities of important quantitative traits in rice (Oryza sativa L.). Six generations viz., P1, P2, F1, F2, BCP1 and BCP2 of a cross between IET6279 and IR70445-146-3-3 were used for the study. Generation mean analysis suggested that additive effects had a major role for the expression of plant height, number of panicles, number of spikelets per panicle, percentage spikelets fertility per plant and grain yield per plant, which further suggested that phenotypic selection was possible at an early stage. Both additive and non-additive gene actions were important for the expression of number of fertile spikelets per panicle and 100-grain weight. Therefore, selection for these characters would be fruitful, if delayed till epistasis effects are reduced to a minimum. High broad sense heritability estimates were observed for characters viz. plant height and 100-grain weight, suggesting that the characters under study are less influenced by environment in their expression. Thus, selection based on phenotypic value of these characters would be reliable and effective. Low estimates of broad sense heritability were observed for number of panicles per plant, number of spikelets per panicle, number of fertile spikelets per panicle, percentage spikelets fertility per plant and grain yield per plant, indicating that influence of the environment was high for these characters. Therefore, superior genotypes selection based on phenotypic performance for these characters may not effective. [ABSTRACT FROM AUTHOR]

Tef [Eragrostis tef (Zucc.) Trotter] is the major cereal crop in the Horn of Africa, especially in Ethiopia where it is a staple food for over 60% of its 90 million population. The crop performs better than other cereal crops under extreme environmental conditions. The grain of tef is not only nutritious but also gluten-free, the cause for celiac disease, which affects humans world wide. The objective of this study was to evaluate the morpho-agronomic performance of newly developed semi-dwarf tef genotypes for grain yield and yield related agronomic traits under diverse environmental conditions. Twenty-four tef lines were evaluated, along with one local and three standard checks, at three locations in the Central Ethiopia. The mean squares due to genotypes, locations and genotype by location interactions were highly significant (P<0.01) for all the studied traits. Three genotypes, namely RIL- 91, RIL-244 and RIL-11, gave the highest seed yield, ranging between 4.4 to 4.7 t ha-1, compared to the popular and widely cultivated tef variety called Quncho which gave 4.2 t ha-1. Genotypic and phenotypic coefficients of variations ranged from 0.002 to 173.9% and from 0.004 to 255.9%, respectively. The highest genetic advance (20.2 cm) and heritability estimates (86.7%) were obtained for plant height indicating that selection for this trait can be made easily. Grain yield showed significant and positive genotypic association with plant height, whole culm and second culm internode length, second culm internode diameter, number of spikelet per panicle and shoot biomass yield. Cluster analysis grouped the genotypes into six distinct classes. The first five principal components with eigenvalues greater than one accounted for 85% of the total variation. Generally, this study identified tef genotypes with better grain yield and reasonable lodging tolerance for further evaluation and eventual release to the farming communities. [ABSTRACT FROM AUTHOR]

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Narrow-sense heritability (portion of the total phenotypic variation attributable to additive genetic effect, h2) is a critical parameter in plant breeding and genetics, but its estimation is difficult for populations with unknown pedigree information. This study applied a marker-based linear mixed model (LMM) analysis to estimate narrow-sense heritability and its seven functional components corresponding to SNPs in coding and noncoding regions for each of 107 flowering, defense, ionomics, and developmental traits in an Arabidopsis ( Arabidopsis thaliana) population of 199 inbred lines with unknown genetic relatedness. Genetic relationship matrix (GRM) based on 214 051 SNPs and component GRMs based on seven subsets of SNPs were computed for LMM estimation of h2 and functional components contributing to h2, respectively. The h2 estimates for flowering traits were higher than those for defense, ionomics, and developmental traits, supporting a general view that the fitness-related traits have lower heritabilities than other traits. The function component owing to SNPs in coding (exon) regions was the least contributor to h2. Our LMM analysis provides an opportunity to gain a comprehensive view on heritability and its functional components for populations with unknown structure but with genome-wide DNA markers. [ABSTRACT FROM AUTHOR]

Relatively few studies have investigated how geography, environmental factors, and genetics affect floral trait variation. We used mixed-mating Collinsia heterophylla Buist to explore variation in a suite of floral traits related to mating system in populations representing four geographic regions of California, USA, and relate this variation to geography, climatic factors, and local site characteristics. We evaluated the environmental vs. genetic trait variability in the greenhouse. Stage of anther-stigma contact correlated positively with temperature, stage of stigma receptivity was negatively associated with vegetation cover, and flower size differed among populations without any clear relation to environmental factors. Greenhouse data indicated heritability for stage of anther-stigma contact, flower size, and time to flowering, and positive correlations between field and greenhouse for stage of stigma receptivity and flower size; however, stage of anther-stigma contact showed a high degree of environmental influence. Stage of anther-stigma contact covaried positively with stage of stigma receptivity and flower size across maternal families, indicating genetic correlations between traits. In conclusion, phenotypic floral variation within mixed-mating C. heterophylla is mostly determined by a genetic component. Geography, environment, and genetics affect traits differently, suggesting that ecological and evolutionary processes contribute to shaping variability in mating system-related traits. [ABSTRACT FROM AUTHOR]

Tomato (Lycopersicon esculentum var. cerasiforme) is among the most important vegetable crops grown world wide providing good nutritional requirements and boost incomes, especially in sub-Saharan Africa. The objective of this study was to determin the heritability of shortened fruit maturation (SFM) period in a hybrid from a cross between cherry (Small fry) tomato and Petomech. A field experiment was carried out at the Crops Research Institute (CRI), Kwadaso. A cross was made between Petomech and Small fry. Fruit maturation period (FMP) (days from anthesis to the breaker stage of fruit Colour) was 42 days for Small fry and 52 days for Petomech. Parental, F1, F2, and backcross generations differed in FMP, yield, estimates of broad- and narrow-sense SFM heritabilities of 61.4 and 38.8%, respectively, on a single-plant basis. A test for midparent heterosis also showed significance (P<0.05). Genetic control of SFM was quantitative in nature, and highly dominant. The F1 and F2 generations had FMP of 47.2 and 49.5 days, respectively. F1, F2, and backcross generations all differed in number of fruits per plant, giving broad- and narrow-sense heritabilities of 69.73 and 55.67%, respectively. With a mean per fruit weight of 150.1 g Petomech recorded the highest fruit weight, while Small Fry recorded the lightest fruit weight of 81.4 g. Estimated broad-and narrow sense heritability for fruit weight was 71.76 and 41.68%, respectively. There was a significant difference between Small Fry and Petomech, as well as the BC1 and BC2 in terms of fruit size. The highest heterotic effect was found in number of fruits per plant (27.6%) over mid-parent. The highest yield was recorded by Petomech (18.9 t ha-1), while Small Fry recorded the lowest value of (14.3 t ha-1). [ABSTRACT FROM AUTHOR]

Copyright of Canadian Journal of Plant Science is the property of Canadian Science Publishing and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Le dimorphisme sexuel est présent dans de nombreux taxa dans le règne animal, notamment chez les mammifères où il est très bien étudié. Ce phénomène a d’abord été perçu comme le résultat direct de la sélection sexuelle et par la suite, d’autres théories ont mis en avant la compétition pour l’accès à la nourriture ou encore la différenciation de niche écologique. Chez la plupart des primates, le dimorphisme sexuel est poussé et bien visible, souvent en relation avec un système social mettant en jeu la polygynie. En revanche, parmi eux, les prosimiens ont un degré de dimorphisme exceptionnellement bas. Parmi eux, les femelles microcèbes femelles sont même plus grandes que les mâles, notamment au niveau du poids ou de la taille, différences occasionnant souvent des performances diverses. On sait notamment que la morphologie a un fort impact sur la force de morsure et les capacités de préhension, mais l'ontogénie et la physiologie musculaire peuvent aussi jouer un rôle. La force de morsure et de préhension ont un rôle écologique démontré chez certaines espèces. Chez le microcèbe pourtant, il a été montré que la force de morsure, reliée à la capacité à se battre chez le mâle, n’était pas un caractère préféré par les femelles dans le cadre de la sélection sexuelle. Le microcèbe est un petit lémurien nocturne originaire de Madagascar ayant un système social de reproduction en promiscuité. Il se reproduit tous les ans et peut vivre jusqu’à 13 ans en captivité. C’est un animal généraliste qui se nourrit d’arthropodes, de gommes et de sécrétions d'insectes. Afin d’étudier les conséquences du dimorphisme morphologique chez les prosimiens, nous avons étudié une colonie de microcèbes captifs en mesurant les dimensions de la tête et des membres et en les pesant. Les performances des animaux ont été évaluées grâce à des outils dotés de piézomètres, nous donnant accès aux forces de morsure et de préhension des membres supérieurs. Les résultats de cette étude nous ont confirmé un dimorphisme sexuel dans la morphologie et une différence légère dans la performance. Ceci nous a aidés à mettre en perspective les théories de différenciation de niche écologique, déjà inférées dans des études précédentes. De plus, nous nous sommes attachés à estimer l’héritabilité de ces caractères entre les mères et les enfants, et entre les frères et sœurs, à l’aide de régressions parent-enfant et de corrélations entre frères et sœurs. Ces estimations nous ont permis de trouver des valeurs positives mais non significatives pour les forces de morsures et pour les forces de préhension. Ces résultats nous ont permis de constituer des données préliminaires à une étude plus approfondie sur l’héritabilité des caractères chez le microcèbe

Sweetpotato (Ipomoea batatas Lam) is a staple food globally, but it has remained underutilised resource in Ghana due to lack of consumer preferred cultivars. There is the need to develop staple-type sweetpotato cultivars which are preferred by consumers to increase sweetpotato use as a food security, health and industrial crop commodity in Ghana. This study was conducted to evaluate the breeding potential of sweetpotato germplasm for the development of farmer and consumer preferred varieties in Ghana. A total of 115 sweetpotato accessions were evaluated for genetic variability. Significant (P<0.01) differences were observed indicating genetic diversity. G x E was significant for all traits, except dry matter, sucrose, total sugar, and starch content. Phenotypic Coefficient of Variation (PCV) ranged from 4.78% for starch content to 63.40% for marketable root weight. Genotypic Coefficient of Variation (GCV) ranged from 4.07% for starch content to 55.35% for marketable root weight. Broad-sense heritability estimates varied from medium (0.61) to high (0.90) for all the traits, except for sucrose content. Predicted improvement over the means is 10 up to 105% for all traits, except starch (7.13%). This indicates sufficient useful genetic variation prospect which could be used to provide substantial improvement through selection of superior genotypes. The strong positive genetic association between dry matter and starch (r = 0.71), and strong negative relationship for sugar and dry matter (r = -0.77) and starch content (r = -0.99) indicates the possibility of developing non-sweet high dry matter sweetpotatoes, which are the preferred varieties in Ghana. [ABSTRACT FROM AUTHOR]

Autism spectrum disorders (ASD) are a heterogeneous group of neuropsychiatric disorders characterized by problems in social communication, as well as by the presence of restricted interests, stereotyped and repetitive behaviours. In the last 40 years, genetic studies have provided crucial information on the causes of ASD and its diversity. In this article, I will first review the current knowledge on the genetics of ASD and then suggest three propositions to foster research in this field. Twin and familial studies estimated the heritability of ASD to be 50%. While most of the inherited part of ASD is captured by common variants, our current knowledge on the genetics of ASD comes almost exclusively from the identification of highly penetrant de novo mutations through candidate gene or whole exome/genome sequencing studies. Approximately 10% of patients with ASD, especially those with intellectual disability, are carriers of de novo copy-number (CNV) or single nucleotide variants (SNV) affecting clinically relevant genes for ASD. Given the function of these genes, it was hypothesized that abnormal synaptic plasticity and failure of neuronal/synaptic homeostasis could increase the risk of ASD. In addition to these discoveries, three propositions coming from institutions, researchers and/or communities of patients and families can be made to foster research on ASD: (i) to use more dimensional and quantitative data than diagnostic categories; (ii) to increase data sharing and research on genetic and brain diversity in human populations; (iii) to involve patients and relatives as participants for research. Hopefully, this knowledge will lead to a better diagnosis, care and integration of individuals with ASD. [ABSTRACT FROM AUTHOR]

Résumé Les rhumatismes inflammatoires regroupent plusieurs maladies qui touchent les articulations et les structures périarticulaires. Dans ces maladies, la contribution génétique est souvent inférieure à 50 %, suggérant une large part « environnementale ». Pour évaluer le rôle de la génétique dans ces maladies, les études les plus appropriées sont celles des jumeaux. Quelques études réalisées sur d’importants effectifs de paires de jumeaux monozygotes (MZ) et dizygotes (DZ), dont l’un des deux est atteint de rhumatisme inflammatoire, permettent de tirer des conclusions probantes. C’est surtout le cas pour la spondylarthrite ankylosante et la polyarthrite rhumatoïde. Pour d’autres maladies, cette évaluation reste plus difficile. Nous verrons ici que génétique et environnement sont inextricablement liés et qu’il est faux d’avoir une vision binaire « génétique » ou « environnement ». Il est important de connaître les limites et les biais possibles des études sur les jumeaux pour mieux comprendre le développement de ces maladies complexes que sont les rhumatismes inflammatoires. [ABSTRACT FROM AUTHOR]

Citrullus lanatus (Thunb.) Matsumura and Nakai (Cucurbitaceae) is an important cucurbit crop worldwide. Global production of watermelon is about 90 million metric tonnes per annum, making it among the top five most consumed fresh fruits. The objective of this study was to evaluate seed variability in different segregating populations, and determine heritability of traits of watermelon. Interspecific crosses were made between two cultivars of C. lanatus (Bebu and Wlêwlê Small Seeds (WSS) were performed at Research Station of Nangui Abrogoua University in Abidjan, Côte d'Ivoire. There was wide variability between parental, F1, BC1 (first generation of back-crossing) and F2 seeds. Seeds of all hybrid populations were intermediate versus those of the parents. Also, crossing did not affect F1 and F2 seed characters, but affected those of BC1 because of maternal effects. Thus, back-crossing on Bebu cultivar produced seeds which looked like those of Bebu; while backcrossing on WSS cultivar produced seeds similar to those of WSS. Principal Component Analysis (PCA) and individuals repartitioning revealed that Bebu and WSS cultivars were genetically distinct and showed three main groups: two groups from each parental line and one from a recombinant line (hybrids). F2 population had a wide individual's dispersion, and contained seeds of all other populations. High heritability was observed for all evaluated characters. [ABSTRACT FROM AUTHOR]

Pre-breeding information on the inheritance mechanism of important sweetpotato (Ipomoea batatas L.) agronomic traits is still limited. This study aimed at assessing the inheritance of five sweetpotato agronomic traits, viz. marketable fresh root yield (MFRY) and number (MNR), total fresh root yield (TFRY) and number (TNR) and root b-carotene content (RBCC). A 5 × 5 full diallel was performed and F1 progenies, evaluated in two environments alongside the parents. The data were subjected to ANOVA and DiallelSAS-05 Griffing's method 1. Simple Sequence Repeat (SSR) based genetic distance and cluster analysis were performed on the parental lines using Jaccard's coefficient and the unweighted pair group method with arithmetic averages (UPGMA). Significant differences (P<0.01) were detected among the genotypes for MFRY, MNR, TFRY, TNR and RBCC. Significant general and specific combining ability (P<0.01) effects were observed for all five traits. Additive gene action was predominantly involved in the inheritance of these traits. High broad sense heritability values were observed for the four yield parameters and for RBCC. The Jaccard's similarity coefficient indicated moderate to low genetic similarity distances among the parents, implying high diversity. The knowledge on the inheritance and diversity of the parental genotypes enables more effective choice of parents in breeding improved varieties. [ABSTRACT FROM AUTHOR]

The analysis concerned 1264 and 811 reproduction records of Boujaâd and Sardi ewes, respectively. Data were collected from 1993-94 to 1999-2000 at Deroua Experimental Station of the Institut national de la recherche agronomique at Béni Mellal. The genetic parameters for reproductive traits were estimated by the REML estimation of variance and covariance components method. Repeatability estimates in Boujaâd ewes were 0.18 and 0.17 for litter size at birth and at weaning, 0.23 and 0.18 for litter weight at birth and at weaning, respectively, and 0.18 for length of pregnancy. Corresponding estimates in Sardi ewes were 0.21 and 0.18, 0.24 and 0.15, and 0.16. Heritability estimates of Boujaâd ewes were 0.18 and 0.11 for litter size at birth and at weaning, 0.18 and 0.11 for litter weight at birth and at weaning, respectively, and 0.04 for length of pregnancy. Corresponding estimates in Sardi ewes were 0.21 and 0.18, 0.24 and 0.15, and 0.16. Genetic and phenotypic correlations between these traits varied from 0.83 to 1.00 and from 0.27 to 0.93 in Boujaâd ewes, and from 0.06 to 0.96 and from 0.07 to 0.82 in Sardi ewes, respectively. It was concluded that these parameters could be used in selection programs to improve productivity in Boujaâd and Sardi ewes.

The analysis concerned 1937 and 2005 fleece weights of Boujaâd and Sardi sheep breeds, respectively. Data were collected during eight years from 1994 to 2001 at Deroua Experimental Station of INRA. Age at shearing, year of shearing and the animal sex had significant effects on the fleece weight of sheep of both breeds. Males under the age of 18 months showed the highest performance. Repeatability and heritability of fleece weights were estimated with the REML method applied to an animal model. Repeatability estimates for fleece weight were 0.46 and 0.57 for Boujaâd and Sardi, respectively, and heritability estimates were 0.27 and 0.40, respectively. The regression of the additive genetic value of each animal for fleece weight, estimated by the BLUP animal model, on its birth year, showed an annual genetic progress of 32 g/year for Boujaâd and 68 g/year for Sardi. It was concluded that selection would be very efficient to improve the fleece weights of Boujaâd and Sardi breeds.

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Copyright of Animal Genetic Resources is the property of Cambridge University Press and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Heritabilities, repeatabilities and genetic and phenotypic correlations among milk yield, fat yield and fat percentage were estimated using an animal model and 20,140 records of 11,618 Holstein-Friesian cows enrolled in the Moroccan official milk-recording program between 1990 and 1999. Heritabilities for milk yield, fat yield and fat percentage were 0.29, 0.27, and 0.39, respectively, and their repeatabilities were 0.33, 0.32, and 0.39, respectively. Genetic correlations of milk yield with fat yield and with fat percentage were 0.96 and –0.32, respectively, and correlation of fat yield with fat percentage was –0.06. Phenotypic correlations were 0.96 between milk and fat yields, –0.28 between milk yield and fat percentage, and –0.03 between fat yield and percentage. It was concluded that these genetic and phenotypic parameters could be used for the genetic evaluation of dairy cattle in Morocco.

Data on the birth weight of 610 lambs produced from 21 rams randomly mated with 199 primiparous Fulbe ewes were collected between 1993 and 1996 at the Institute of Agricultural Research for Development, Garoua Research Station. Data were used to identify and quantify factors affecting the birth weight (BWT) and litter birth weight (LBWT), and to estimate direct and maternal heritabilities, genetic and phenotypic correlations between direct and maternal effects. Results indicated that 26.86% variability in BWT and 34.20% in LBWT were caused by sex, season of birth, year of birth, parity, birth type and feed group. Heavier lambs (2.36 kg) were produced during the cold dry season (October to January). Mixed litters had significantly higher weights (3.97 kg) than litters only composed of either males (2.73 kg) or females (2.64 kg). Estimates for direct and maternal heritabilities were 0.61 and 0.32 for BWT, and 0.30 and 0.27 for LBWT. Estimates for genetic and phenotypic correlations between direct and maternal effects were -0.48 and 0.28 for BWT, and -0.65 and 0.57 for LBWT. Due to the high negative estimates for genetic correlations, long-term selection on own performance for either BWT or LBWT will adversely affect maternal performance.

Knowledge of genetic parameters for growth traits of economic importance is required for the development of sheep populations in Morocco. Records on 544 lambs of the Timahdite (T) breed and of 756 D'man x Timahdite (DT) lambs, all born from 1992 to 1998, were used to estimate genetic parameters for lamb weights at birth, at 30, 70 and 90 days and daily gains from 10-30 days, 30-70 days and 30-90 days for each trait. Separate REML (co)variance component estimates were obtained assuming animal models that included the fixed effects of birth year, sex, age of dam, birth type or rearing types and the interaction of birth year by sex, the animal direct genetic effect and the maternal genetic effect. Genetic and phenotypic correlations between traits were estimated with models including the same fixed effects and only additive direct genetic effects. All fixed effects influenced growth traits. The direct heritability estimates for the various body weight and daily gain traits were low to medium and varied between 0.07 and 0.25 in T, and between 0.02 and 0.18 in DT. Maternal heritability ranged from 0.20 to 0.36 in DT, and from 0.01 to 0.10 in T lambs, except for the birth weight (0.53). For all traits the direct and maternal genetic correlations were high and negative in DT (-0.80 and -1.00) and in T (-0.90 and -1.00) lambs. However, the accuracy of such estimates is low due to the small data set used in the present study. The estimates of genetic and phenotypic correlations were positive for all traits, they were particularly high for genetic correlations between weights and weight gains after birth, both in DT and T lambs, and they showed no genetic antagonisms among the growth traits.

Copyright of Biotechnologie, Agronomie, Societe et Environnement is the property of Les Presses Agronomiques de Gembloux and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Genes and environment make the organism. Darwin stood firm in his denial of any direct role of environment in the modification of heredity. His theory of evolution heralded two debates: one about the importance and adequacy of natural selection as the main mechanism of evolution, and the other about the role of genes versus environment in the modification of phenotype and evolution. Here, I provide an overview of the second debate and show that the reasons for the gene versus environment battle were twofold: first, there was confusion about the role of environment in modifying the inheritance of a trait versus the evolution of that trait, and second, there was misunderstanding about the meaning of environment and its interaction with genes in the production of phenotypes. It took nearly a century to see that environment does not directly affect the inheritance of a phenotype (i.e., its heredity), but it is nevertheless the primary mover of phenotypic evolution. Effects of genes and environment are not separate but interdependent. One cannot separate the effect of genes from that of environment, or nature from nurture. To answer the question posed in the title, it is partly because the 20th century has been a century of unending progress in genetics. But also because unlike physics, biology is not colorblind; progress in biology has often been delayed beyond the Kuhnian paradigm change due to built-in interest in negating the influence of environment. Those who are against evolution, of course, cannot be expected to understand the role of environment in evolution. Those for it, many biologists included, believing in the supremacy of genes empowers them by giving adaptation a solely gene-directed (self-driven) 'teleological' interpretation. [ABSTRACT FROM AUTHOR]