Presence Of Genetic Variation Research Articles

Heritability estimates for growth and salt-resistance traits of Urechis unicinctus

The echiura worm Urechis unicinctus has high economic and nutritional value and has emerged as a promising species for aquaculture development. Selective breeding plays a crucial role in enhancing growth and production, and estimating the narrow-sense heritability is the initial step in implementing selective breeding programs. To assess the proportion of additive genetic variation in growh and salt-tolerance traits, this study used 20 families to measure genetic parameters for growth traits at the 100-day and 200-day stages (weight, length, and width) and two salinity conditions (high and low salt). For growth traits, moderate to high heritability estimates were observed at both the 100-day and 200-day stages, ranging from 0.24 ± 0.08 (body width) to 0.42 ± 0.12 (body weight) and 0.40 ± 0.11 (body width) to 0.72 ± 0.16 (body weight), respectively. The genetic and phenotypic correlation coefficients between these traits were found to be intermediate to high across the two testing periods, and these results were supported by significant Pearson correlation (P < 0.01). Regarding salt-tolerance traits, different families exhibited varying survival times under salinity stress, indicating distinct viability responses. The heritability estimates for high-salt and low-salt tolerance were 0.73 ± 0.22 and 0.16 ± 0.06, respectively. The genetic correlation coefficients between salt tolerance and body weight were 0.39 ± 0.16 and 0.89 ± 0.05. Additionally, a positive Pearson correlation was observed between these traits (P < 0.01), suggesting the feasibility of indirect breeding. Overall, these findings indicate the presence of genetic variation in the growth and salt-tolerance traits of U. unicinctus and highlight the potential for genetic improvement through selective breeding techniques. The results provide valuable information to guide effective selection of U. unicinctus.

Genetic Variability, Heritability and Genetic Advance in F2 Segregating Population of Cross RNR-15048 x Dokra-Dokri in Rice (Oryza sativa L.)

The present experiment was conducted to study the variability, heritability and genetic advance in F2 segregating population derived from the cross, RNR-15048 x Dokra-Dokri, evaluated in augmented design with two checks at ICAR-IIRR, Hyderabad during the Kharif-2022. Analysis of variance revealed the presence of significant differences for all eleven traits examined, indicating the presence of genetic variation between the individuals studied. Higher values of Genotypic Coefficient of Variation (GCV) and Phenotypic Coefficient of Variation (PCV) were observed for panicle weight, number of filled grains, number of unfilled grains, total grains per panicle, and single plant yield. Least difference was observed between PCV and GCV value for almost all the traits indicating the little influence by the environment and possibility for genetic improvement of these traits through selection. The traits plant height, panicle weight, number of filled grains, number of unfilled grains, total grains per panicle, spikelet fertility, thousand grain weight and single plant yield recorded high heritability (&gt;60%) associated with high genetic advance as percent of mean (&gt;20) resulting in no environmental influence on the expression and selection for improvement of such characters could be worthwhile. High heritability coupled with moderate genetic advance as percent of mean was observed for panicle length propounding non-additive gene action in their inheritance suggesting heterosis breeding could be useful for improving these traits. Overall high PCV and GCV coupled with high heritability and high genetic advance as percent of mean was noticed for panicle weight, number of filled grains, number of unfilled grains, total grains per panicle, and single plant yield suggesting significant amount of variability with predominance of additive type of gene action. Hence, direct phenotypic selection.

Analyzing genetic variation for important yield-contributing attributes in genotypes of orange-fleshed sweet potatoes

An experiment was conducted to estimate genetic variability of 47 orange-fleshed sweetpotato(OFSP) genotypes. It was established in two locations(Umudike and Igbariam) in a RCBD fashion with three replications. Data collected were subjected to ANOVA using the software; AGD-R. The results showed that all the characters studied were highly significant (p&lt;0.01) for genotypes. All the traits were significant for location except the vine length, days to 50% flowering and root yield. Most of the characters were also significant for genotypes-location interaction. Significant differences observed among genotypes for most traits indicated the presence of genetic variation among the materials. The genotypic coefficient of variation(GCV) was very high for beta carotene(73.8%) and vitamin A(70.0%). Phenotypic coefficient of variation(PCV) was very high for beta carotene(183.5%), root yield per hectare(151.6%), total root weight per plant(150.6%) and total number of roots per plant(113.5%). The PCV was higher than their corresponding GCV for all the characters studies, indicating that the expression of these characters was influenced by environment. The GCV was consistently higher than PCV in all the traits. The genotypic variance was high for days to 50% flowering(373.16), dry matter(220.30), root girth (140.73), root length (68.10) and root yield per hectar (349.66). The magnitude of VA was consistently larger than that of VD for all the traits suggesting that the additive genetic variance was more important than the dominance genetic variance in the inheritance of most studied traits. All the characters studies had high heritability (&gt;60%). High heritability estimates for those traits indicated a high response to selection

Mechanisms of robustness in gene regulatory networks involved in neural development.

The functions of living organisms are affected by different kinds of perturbation, both internal and external, which in many cases have functional effects and phenotypic impact. The effects of these perturbations become particularly relevant for multicellular organisms with complex body patterns and cell type heterogeneity, where transcriptional programs controlled by gene regulatory networks determine, for example, the cell fate during embryonic development. Therefore, an essential aspect of development in these organisms is the ability to maintain the functionality of their genetic developmental programs even in the presence of genetic variation, changing environmental conditions and biochemical noise, a property commonly termed robustness. We discuss the implication of different molecular mechanisms of robustness involved in neurodevelopment, which is characterized by the interplay of many developmental programs at a molecular, cellular and systemic level. We specifically focus on processes affecting the function of gene regulatory networks, encompassing transcriptional regulatory elements and post-transcriptional processes such as miRNA-based regulation, but also higher order regulatory organization, such as gene network topology. We also present cases where impairment of robustness mechanisms can be associated with neurodevelopmental disorders, as well as reasons why understanding these mechanisms should represent an important part of the study of gene regulatory networks driving neural development.

Genetic variability Analysis for various Yield Contributing Traits in Orange-Fleshed Sweetpotato Genotypes

An experiment was conducted to estimate genetic variability of 47 orange-fleshed sweetpotato (OFSP) genotypes. It was established in two locations (Umudike and Igbariam) in a RCBD fashion with three replications. Data collected were subjected to ANOVA using the software; AGD-R. The results showed that all the characters studied were highly significant (p&lt;0.01) for genotypes. All the traits were significant for location except the vine length, days to 50% flowering and root yield. Most of the characters were also significant for genotypes-location interaction. Significant differences observed among genotypes for most traits indicated the presence of genetic variation among the materials. The genotypic coefficient of variation (GCV) was very high for beta carotene (73.8%) and vitamin A (70.0%). Phenotypic coefficient of variation (PCV) was very high for beta carotene(183.5%), root yield per hectare(151.6%), total root weight per plant(150.6%) and total number of roots per plant(113.5%). The PCV was higher than their corresponding GCV for all the characters studies, indicating that the expression of these characters was influenced by environment. The GCV was consistently higher than PCV in all the traits. The genotypic variance was high for days to 50% flowering (373.16), dry matter (220.30), root girth (140.73), root length (68.10) and root yield per hectare (349.66). The magnitude of VA was consistently larger than that of VD for all the traits suggesting that the additive genetic variance was more important than the dominance genetic variance in the inheritance of most studied traits. All the characters studies had high heritability (&gt;60%). High heritability estimates for those traits indicated a high response to selection.

Relationship between the Polymorphism of the AKT1 Gene and the Consumption of Cannabis in the Appearance of Psychosis

Introduction: Psychotic disorders are a mental illness that affect 3% of the world’s population. The external (cannabis) and internal vulnerability factors (polymorphisms of the AKT1 gene, the COMT gene and the DAT1 gene) acquire special relevance in the appearance of psychosis; this is known as the vulnerability–stress model. Objective: To analyze the scientific evidence that reflects the relationship between the polymorphism of the AKT1 gene and the consumption of cannabis in the appearance of psychosis. Material and Methods: The bibliographic search was made using databases such as Scopus, WoS, Cochrane Library, TRIP Database, PubPsych and PubMed. The criteria of the “MeSH” terminology and the inclusion and exclusion criteria were followed, obtaining a total of 22 articles that comprises this narrative review. Results: The presence of genetic variation in the locus rs2494732 of the AKT1 gene in a cannabis user raises the risk of the appearance of psychosis, especially if homozygous with the C allele. Likewise, consumption entails a slowdown in the functionality of the AKT1 gene, releasing a greater amount of dopamine in the striatum through the involvement of indirect mechanisms. Similarly, the COMT gene and the interaction of the AKT1 gene with the DAT1 gene raise the risk of developing psychotic disorder. Conclusion: The genetic polymorphism rs2494732 of AKT1 is the main factor responsible for the appearance of psychosis, although polymorphisms of the COMT and DAT1 gene are also implicated. Regarding the AKT1 gene, subjects with two copies of the C allele have a higher risk of developing psychosis compared to subjects with two copies of the T allele. It should also be noted that the muscarinic receptors rs115455482 and rx74722579 are related to a greater vulnerability to psychosis and the development of psychotic disorders.

Appraisal of genetic variability in sodium azide induced rice mutants to identify selection criteria for higher yield using quantitative attributes

Induced mutation is an effective tool in generating variability of crop plants. Identification of efficient genotypes with improved yield requires knowledge of genetic variation in yield and yield contributing traits. Therefore, an investigation was conducted to develop variants through azide mutagenesis and estimation of genetic variability of the mutants to detect selection standards towards higher yield. Mature rice seeds were mutagenized with estimated LD50 concentration. A hundred mutants were grown-up accordingly and their quantitative traits were evaluated through multivariate analysis to assess genetic variability. Every assessed trait except grain length exhibited highly significant variation for all mutants. The high genotypic and phenotypic coefficient of variation along with high heritability and genetic advance as a % of mean was accounted for total and filled grains panicle-1. Grain yield was positively and significantly correlated with total grains panicle-1, filled grains panicle-1 and straw yield hill-1. Besides, higher variance was also associated with these traits. Ward’s Agglomerative clustering grouped the mutants into 7 major clusters. More than 36% of total variation was associated with first 2 principal components (PCs) and was mostly with total grains panicle-1 and filled grains panicle-1 whereas third and fourth PCs were mainly accounted for straw yield hill-1. Thus, these traits should receive special attention during selection of yield potential genotypes. Presence of genetic variation in mutants was ensured for most of the traits and selection based on greater tillers hill-1, grains panicle-1 and straw yield hill-1 may open a new avenue towards improved yield and other traits in rice.

Performance and Genetic Variability of Okra (Abelmoschus esculentus (L.) Moench) Genotypes in Ethiopia for Agromorphology and Biochemical Traits

No research has been done to assess the genetic diversity of Okra (Abelmoschus esculentus) genotypes in Ethiopia based on the combination of agromorphology and biochemical traits of the crop. Such an assessment would assist in the development of high fruit yield and nutritionally good cultivars. Therefore, 36 okra genotypes were evaluated for 29 agromorphological and biochemical traits at the Melkassa Agricultural Research Center (Ethiopia) during the 2018 main rainy season, using a 6 × 6 simple lattice design. Analysis of variance showed significant differences among genotypes for all the studied traits, except number of flower epicalyxes and fruit diameter. Genotypic coefficients of variation and phenotypic coefficient of variation were high for number of branches, internode length, fresh fruit weight, number of mature pods, fruit yield per plant, fruit yield per hectare, seed yield per plant, seed yield per hectare, and seed protein content. Heritability values ranged between 33.63 and 99.81%, while the genetic advance as percentage of mean ranged between 4.29 and 95.45%. High broad sense heritability was coupled with high GAM for plant height, branch, internod length, fruit length, panicle length, fresh fruit weight, number of fruits per plant, number of mature pods, seed yield per plant, seed yield per hectare, and fibre and protein content. In conclusion, this study showed the presence of genetic variation among genotypes for fruit yield, seed yield, and nutritional content, indicating the potential success of developing okra varieties for high fruit yielding and good nutritional content.

Repeatability of Voluntary Thermal Maximum and Covariance with Water Loss Reveal Potential for Adaptation to Changing Climates.

AbstractAlthough climate warming poses a grave threat to amphibians, little is known about the capacity of this group to evolve in response to warming. The capacity of key traits to evolve depends on the presence of genetic variation on which selection can act. Here, we use repeatability estimates to estimate the potential upper bounds of heritable genetic variation in voluntary and critical thermal maxima of gray-cheeked salamanders (Plethodon metcalfi). Increases in thermal tolerance may also require concordant increases in resistance to water loss because hotter temperatures incur greater evaporative risk. Therefore, we also tested for a correlation between voluntary thermal maxima and resistance to water loss and conducted an acclimation study to test for covariation between these traits in response to warming. Voluntary thermal maxima exhibited low to moderate levels of repeatability (, ), while critical thermal maxima exhibited no statistically significant repeatability (, ). Voluntary thermal maxima also correlated positively with resistance to water loss (, ) but only when controlling for body mass. Voluntary thermal maxima and resistance to water loss also exhibited different acclimatory responses across control (12°C-18°C) and warm (18°C-24°C) temperature regimes, indicating a potential decoupling of traits in different thermal environments. By addressing the repeatability of thermal tolerance and the potential for covariation with resistance to water loss, we begin to address some of the key requirements of amphibians to evolve in warming climates.

Determination of Salt Tolerance of Some Lentil (Lens Culinaris Medic.) Varieties During Germination Period

In this study, in order to determine the resistance of registered lentil varieties to different salt concentrations during germination periods, this study was carried out in 2020 in University of Selçuk Faculty of Agriculture Department of Field Crops Laboratory in 4 replications according to the Randomized Plots Design. Çağıl, Çiftçi, Evirgen, Fırat-87, Kafkas, Özbek, Şakar, Şanlıbey and Tigris varieties were used as materials in the study. The effects of different salt concentrations (0 (control), 30 mM, 60 mM, 90 mM and 120 mM) on germination rate, germination speed, average germination time and sensitivity index were investigated. As a result of the study, it was determined that there were decreases in all the traits examined compared to the control application due to the increase in salt concentrations in all varieties. Especially in 90 and 120 mM NaCl applications, it was determined that the salt tolerance of the varieties decreased. Lentil varieties have been differently affected by salt applications, and the presence of genetic variation between varieties has helped us identify salt-resistant varieties. The varieties most sensitive to salinity were determined as Evirgen and Tigris. When all parameters are evaluated together, Özbek, Çağıl and Şanlıbey varieties have been determined as the best performing genotypes in terms of salt resistance.

Screening by single-molecule molecular inversion probes targeted sequencing panel of candidate genes of infertility in azoospermic infertile Jordanian males

Infertility is a common health problem that affects around 1 in 6 couples in the United States, where half of these cases are attributed to male factors. Genetics play an important role in infertility and it is estimated that up to 50% of cases are due to genetic factors. Despite this, many male infertility cases are still idiopathic. This study aimed to identify the presence of possibly pathogenic rare variants in a set of candidate genes related to azoospermia in 69 Jordanian men using a next-generation sequencing-based panel covering more than a hundred male infertility related genes. A total of 9 variants were found and validated. Among them, two variants included reported pathogenic variants in CFTR and one novel pathogenic variant in the USP9Y gene. We also report the detection of 6 other variants with uncertain significance in other genes. Interestingly, male cases with CFTR variants did not show the expected cystic fibrosis phenotypes except for infertility. This work helps to uncover the contribution of additional genetic factors to the aetiology of male infertility and highlights the importance to obtain more reliable information about the presence of genetic variation in the Jordanian population.

CRISPR-Cas-mediated chromosome engineering for crop improvement and synthetic biology.

Plant breeding relies on the presence of genetic variation, as well as on the ability to break or stabilize genetic linkages between traits. The development of the genome-editing tool clustered regularly interspaced short palindromic repeats (CRISPR)-CRISPR-associated protein (Cas) has allowed breeders to induce genetic variability in a controlled and site-specific manner, and to improve traits with high efficiency. However, the presence of genetic linkages is a major obstacle to the transfer of desirable traits from wild species to their cultivated relatives. One way to address this issue is to create mutants with deficiencies in the meiotic recombination machinery, thereby enhancing global crossover frequencies between homologous parental chromosomes. Although this seemed to be a promising approach at first, thus far, no crossover frequencies could be enhanced in recombination-cold regions of the genome. Additionally, this approach can lead to unintended genomic instabilities due to DNA repair defects. Therefore, efforts have been undertaken to obtain predefined crossovers between homologues by inducing site-specific double-strand breaks (DSBs) in meiotic, as well as in somatic plant cells using CRISPR-Cas tools. However, this strategy has not been able to produce a substantial number of heritable homologous recombination-based crossovers. Most recently, heritable chromosomal rearrangements, such as inversions and translocations, have been obtained in a controlled way using CRISPR-Cas in plants. This approach unlocks a completely new way of manipulating genetic linkages, one in which the DSBs are induced in somatic cells, enabling the formation of chromosomal rearrangements in the megabase range, by DSB repair via non-homologous end-joining. This technology might also enable the restructuring of genomes more globally, resulting in not only the obtainment of synthetic plant chromosome, but also of novel plant species.

Exploration of genetic structure and association mapping for fibre quality traits in global flax (Linum usitatissimum L.) collections utilizing SSRs markers

Flax is the third largest natural fibre crop and one of the five top oilseed crops in the World. In spite of flax value as fibre and food source, research directed towards the improvement of cultivated flax has been limited due to availability of less information on population structure and marker-fibre quality traits- association. In this context, the present investigation was carried out for estimation of genetic structure and to evaluate the association between fibre quality traits and SSRs marker in 264 global flax collections. Three fibre quality traits were considered for the association mapping and all the traits were showed the significant variation and normal distribution in the current flax population. The overall relative magnitude of genetic differentiation among the populations was 0.45 and also low level of gene flow (Nm = 0.61 < 1) between the populations was observed. The population structure and cluster analysis divided the 264 global flax population in to eight genetic groups which also indicated the presence of genetic variation. The association mapping was analyzed using general linear model (Q) and mixed linear model (Q = K) followed by generated Manhattan plot. The Manhattan plot based on MLM that identified two allele (Lu-10-600 bp and Lu-15-300 bp) associated with fibre length, one allele (Lu-7-150) associated with fibre strength and four allele (Lu-5-50 bp, Lu-7-150 bp, Lu-10-600 and Lu-15-300 bp) associated with fibre yield per plant. The findings of the association mapping of fibre yield was consistent with the earlier QTL analysis in flax but the association mapping with fibre length and fibre strength was first time reported in this study.

Genetic variation among full-sib families and the effect of non-genetic factors on growth traits at harvest in Clarias magur (Hamilton, 1822)

Magur (Clarias magur) is an Indian catfish species with a good potential for aquaculture. The expansion of magur aquaculture is hindered because of low reproductive and survival rates. Furthermore, males need to be sacrificed to collect milt for artificial fertilization. At present, magur seed production mainly depends on the wild-caught juveniles and to a smaller extent, from broodfish whose genetic potential is unknown. The availability of high-quality seeds in a sustainable way can be ensured through the selective breeding program for magur. The knowledge of factors influencing growth traits and their genetic parameters is a pre-requisite for implementing a genetic selection program. The present study aimed to quantify the performance of C.magur reared in a two-year class and estimate their heritabilities at stocking and harvest and also to estimate the genetic and phenotypic correlations among them. The growth traits such as Body Weight (BW), Total Length (TL), Body Depth (BD), Head Width (HW), and Average Daily Gain (ADG) were recorded from 1413 animals belonging to 78 fullsib families produced by adopting single pair mating design, after one year of pond culture (traits at harvest). Genetic parameters were also estimated for body weight (BW0) and total length (TL0) measured from 2328 fish from 78 fullsib families at the time of stocking. Magur attained an average BW of 135 g and 24.5 cm TL after one year culture period. The heritabilities of BW, TL, and ADG were 0.44 ± 0.07, 0.32 ± 0.06, and 0.42 ± 0.07, respectively and may be biased upwardly due to the single pair mating design. Genetic correlations between harvest traits were all positive and varied in magnitude between traits (0.74 to 0.99). The results obtained from the current study indicate the presence of genetic variation in magur population for growth traits and selection based on genetic merit can produce improvement in these traits.

Identification of genetic variants controlling RNA editing and their effect on RNA structure stabilization.

Post-transcriptional modification of RNA (RNA editing, RNAe) results in differences between the RNA transcript and the genomic DNA sequence (RDD). Enzymatic modification of adenosine to inosine (A2I) by ADAR is the most studied type of RNAe. However, few genetic association studies with A2I RNAe events have been conducted. Some studies have analyzed the inter-population RNAe-QTL diversity in humans, but the sample size of these studies was limited. Other types of RNA and DNA differences have been reported but are largely understudied. Here, we report a comprehensive analysis of all types of RDD, based on two independent datasets. We found that A2I was by far the most observed type of RDD. Moreover, manual curation suggests that A2I is likely the only enzymatically driven RNAe type observed in blood derived DNA, all other non-A2I RDD could either be attributed to sequencing and processing artifacts, or are a result of somatic DNA rearrangements. We then conducted an in-cis genetic association study and identified 472 genetic associations (RNAe-QTL), that were replicated in both datasets. We confirm the potential effect of the RNAe-QTL on RNA structure by showing that allele specific RNAe occurs in heterozygotes. Although the generally assumed function of RNAe is to destabilize double stranded RNA structure, we found clear evidence for the potential additional involvement of RNAe in maintaining RNA hairpin that has been altered by the RNAe-QTL. Our study confirms, in two independent datasets, the potential role of RNAe in maintaining RNA structure in the presence of genetic variation.

Assessment of genetic variability, heritability and genetic advance for physio-biochemical and root traits in groundnut (Arachis hypogaea L.) under irrigated conditions

Crop: Groundnut is one of the proteins and oil-producing legume crop of arid and semi-arid regions of the world. The Objective of the study: To estimate the genotypic coefficient of variation, heritability and genetic advance for physio-biochemical and root related traits among groundnut germplasm under the irrigated condition and To put guideline to establish a breeding program for developing genotype (s) with higher yield using suitable selection criteria through genetic variability studies.Research location and season: The College of Horticulture, Hiriyur during rabi 2016-17. Experimental design: Randomized complete block design with two replications. Methodology: forty groundnut genotypes including ICRISAT based advanced breeding lines and existed cultivars were evaluated under field condition. The crop was taken care of as per the standard recommended package of practices. Data was recorded on physio-biochemical and root related parameters at different stages of crop growth. The resulted mean data was subjected to statistical analysis using Genstat 14.1 software. Results: Results revealed highly significant differences for all the traits under study indicating the presence of genetic variation among the genotypes. The characters like MSI (99.89 & 112.99%), leaf phenols (99.63 & 74.26%), seed phenols (99.06 & 73.05%) and root to shoot ratio (86.19 & 21.04%) exhibited high heritability coupled with high genetic advance over mean. Conclusion: It can be concluded that the presence of additive gene action in governing these traits. Thus, there is ample scope for improving these characters based on the direct selection from the genetic stock studied which means if these characters are subjected to any selection scheme for exploiting fixable genetic variance; a widely adopted genotype can be developed.

English

The presence of genetic variation in plant populations is useful for conservation and use in breeding programs. This study was conducted to estimate the extent and patterns of genetic diversity among 200 sorghum accessions collected from different parts of Ethiopia and preserved in a gene bank. Using 39 polymorphic simple sequence repeat (SSR) markers, which were previously mapped, 261 alleles were produced with mean 6.7 alleles per SSR. Polymorphism Information Content (PIC) and Dice’s similarity coefficient values ranged from 0.06 to 0.81 and from 0.062 to 0.96, respectively. Hierarchical clustering using UPGMA analysis revealed three major clusters with no clear distinction among geographical origins. Moreover, analysis of molecular variance (AMOVA) indicated that the majority of the variation (99.62%) observed was attributed to differences among accessions and only a small fraction of the total variation (0.38%) was related to regions of original collection, which may indicate that geographical origin is not a useful guide to follow for germplasm collection. Rather, agro-ecological classifications may be better for collection mission. Furthermore, crossing of accessions from the three distant clusters could result in promising genotypes for use as varieties or parents for the future breeding programs. Key words: Allele, cluster, genetic variability, polymorphism information content, sorghum, SSR.

DOZ047.32: Infantile hypertrophic pyloric stenosis in patients with esophageal atresia: proposal for a causative seesaw model

Abstract Aim of the Study Patients born with esophageal atresia (EA) appear to have a 30 times higher prevalence of infantile hypertrophic pyloric stenosis (IHPS). This makes sense from a developmental perspective as both the esophagus and the pyloric sphincter are foregut derived structures. We hypothesized that genetic defects, disturbing foregut morphogenesis, are responsible for the specific combination of EA and IHPS. Methods Patients with both EA and IHPS born between 1970 and 2017 and where possible their parents were included. This study was approved by the internal review board of the Erasmus MC. After parental written informed consent, we determined genetic profiles with whole exome sequencing and SNP-array-based copy number variation analysis. We focused on (1) genetic variation in known EA and IHPS disease genes, (2) pathways important for foregut morphogenesis, (3) shared rare genetic variation, and (4) ultrarare variants in variant-intolerant genes, which have a high chance of being de novo. Segregation analysis of possible candidate variants was performed. Results Twenty-seven out of 664 patients (4.1%) born with EA during the study period developed IHPS, of which 15 cases were analyzed. As none of the parents were affected, we considered dominant (de novo) or recessive and X-linked inheritance models. Unfortunately, we could neither identify rare de novo mutations, nor variants fitting a recessive model. We did however identify inherited putative deleterious heterozygous variants in genes either known to be involved in EA or IHPS (e.g., COL7A1, TNXB, WDR11, GDF6) or important in foregut morphogenesis (e.g., GLI3, NKX2.1) in all patients. Moreover, seven genes were affected by rare variation in ≥2 patients (ADAMTSL4, ANKRD26, CNTN2, HSPG2, KCNN3, LDB3, SEC16B) and expressed in the developing foregut, esophagus or pyloric sphincter in mice between E8.25 and E18.5. However, burden analysis did not show a significant difference with unaffected controls. Conclusions Although the presence of genetic variation in likely candidate genes suggests a genetic component, genetic factors alone could not explain the abnormalities seen in these patients. Therefore, we propose a multifactorial model in which the combination of high impact genetic, mechanical, and environmental factors together can shift the balance from normal to abnormal development.

DEVELOPMENT OF IN VITRO SOMACLONAL VARIATION FOR PELARGONIUM GRAVEOLENS L’HERIT, AIT

In vitro somaclonal variation via callus is considered as one of the most effective tool for improvement of vegetative propagated crops. Different combinations of cytokinine (BA) and auxine (NAA) were used to induce somaclonal variation from leaf explants of the Egyptian geranium cultivar, Pelargonium graveolens L’Herit, Ait. El Qanater El khayria cv.8. Callus induction and regenerated shoots from callus were evaluated; 2.5 mg/L BA and 0.5 mg/L NAA was the optimal for callus induction and number of regenerated shoots. The obtained plantlets were acclimatized under glasshouse conditions with 80% to 90% survival and were transferred to the open field. The evaluation of growth traits and oil analysis were done for the new 13 clones compared with the mother plant in randomized block design for two successive seasons. Characterization of these new clones for morphological traits and essential oil yield and quality demonstrated the induction of variability in negative and positive directions in some characteristics in comparison with the mother plant. Clone no.7 was the superior clone in herb 2264.7 & 2357.3 g/plant and oil yield 2.436 & 3.065 ml/plant in first and second season, respectively, than the mother plant and other new clones with acceptable content of citronellol 25.63% and geraniol 26.52% as a parameter for volatile oil quality. The genetic variation of the new geranium clones were tested using SRAP technique based on PCR, the polymorphism was detected using 16 pairs of SRAP primers in combinations as forward and reverse. The genetic differences between new clones and the mother plant were ascertained with SRAP primer pair (me2 em4); a unique profile for clone no.7 was detected in SRAP analysis. The similarity percentage varied between 66.7% to 100% homologies among the new clones and their mother plant. The presence of genetic variation between new clones and the mother plant proved that the calliclones were somaclonal mutants, and the geranium cultivar, El Qanater El khayria cv.8, was improved for high yield in herb and essential oil.

Impact of Genetic Selection for Increased Cattle Resistance to Bovine Tuberculosis on Disease Transmission Dynamics

Bovine tuberculosis (bTB) poses a challenge to animal health and welfare worldwide. Presence of genetic variation in host resistance to Mycobacterium bovis infection makes the trait amenable to improvement with genetic selection. Genetic evaluations for resistance to infection in dairy cattle are currently available in the United Kingdom (UK), enabling genetic selection of more resistant animals. However, the extent to which genetic selection could contribute to bTB eradication is unknown. The objective of this study was to quantify the impact of genetic selection for bTB resistance on cattle-to-cattle disease transmission dynamics and prevalence by developing a stochastic genetic epidemiological model. The model was used to implement genetic selection in a simulated cattle population. The model considered various levels of selection intensity over 20 generations assuming genetic heterogeneity in host resistance to infection. Our model attempted to represent the dairy cattle population structure and current bTB control strategies in the UK, and was informed by genetic and epidemiological parameters inferred from data collected from UK bTB infected dairy herds. The risk of a bTB breakdown was modeled as the percentage of herds where initially infected cows (index cases) generated secondary cases by infecting herd-mates. The model predicted that this risk would be reduced by half after 4, 6, 9, and 15 generations for selection intensities corresponding to genetic selection of the 10, 25, 50, and 70% most resistant sires, respectively. In herds undergoing bTB breakdowns, genetic selection reduced the severity of breakdowns over generations by reducing both the percentage of secondary cases and the duration over which new secondary cases were detected. Selection of the 10, 25, 50, and 70% most resistant sires reduced the percentage of secondary cases to <1% in 4, 5, 7, and 11 generations, respectively. Similarly, the proportion of long breakdowns (breakdowns in which secondary cases were detected for more than 365 days) was reduced by half in 2, 2, 3, and 4 generations, respectively. Collectively, results suggest that genetic selection could be a viable tool that can complement existing management and surveillance methods to control and ultimately eradicate bTB.