Genetic Groups Research Articles

Reticulate evolution and rapid development of reproductive barriers upon secondary contact in a forest fungus

Reproductive barriers between sister species of the mushroom-forming fungi tend to be stronger in sympatry, leading to speculation on whether they are being reinforced by selection against hybrids. We have used population genomic analyses together with invitro crosses of a global sample of the wood decay fungus Trichaptum abietinum to investigate reproductive barriers within this species complex and the processes that have shaped them. Our phylogeographic analyses show that T.abietinum is delimited into six major genetic groups: one in Asia, two in Europe, and three in North America. The groups present in Europe are interfertile and admixed, whereas our crosses show that the North American groups are reproductively isolated. In Asia, a more complex pattern appears, with partial intersterility between subgroups that likely originated independently and more recently than the reproductive barriers in North America. We found pre-mating barriers in T.abietinum to be moderately correlated with genomic divergence, whereas mean growth reduction of the mated hybrids showed a strong correlation with increasing genomic divergence. Genome-wide association analyses identified candidate genes with programmed cell death annotations, which are known to be involved in intersterility in distantly related fungi, although their link here remains unproven. Our demographic modeling and phylogenetic network analyses fit a scenario where reproductive barriers in Trichaptum abietinum could have been reinforced upon secondary contact between groups that diverged in allopatry during the Pleistocene glacial cycles. Our combination of experimental and genomic approaches demonstrates how T.abietinum is a tractable system for studying speciation mechanisms.

Genetic structure and climate niche differentiation among populations of Leopardus geoffroyi.

Geoffroy's cat (Leopardus geoffroyi) is a small-sized felid native to South America. Given the species' distribution covering a wide variety of habitats, and the presence of high levels of anthropization in part of its range, it is possible that genetically differentiated groups exist and that they occupy different climatic niches. We assessed patterns of contemporary genetic diversity and structure in the species across most of its range, characterizing each inferred genetic group based on ecological niche models. We genotyped 11 microsatellites for 142 samples covering most of Geoffroy's cat distribution, and investigated patterns of genetic structure and diversity, applying spatial and nonspatial Bayesian clustering methods and a spatial principal component analysis. We created ecological niche models for each genetic cluster, evaluating whether these clusters occupy different climatic spaces and display differences in the suitability of different values of the climatic variables analyzed. We identified two genetic clusters, one in the north-northeast and the other in the south-southwest of the species' distribution. These clusters showed moderate FST values between them and differences in dispersal/genetic diversity. We found isolation-by-distance patterns globally and within each cluster. We observed lower expected heterozygosity compared with other studies and a north-south gradient in allelic richness. The southern cluster showed lower genetic variability and a more restricted climatic niche suggesting that this group is more vulnerable to the effects of the current context of climate change. Individuals from the southern genetic cluster are under different pressures, likely a product of the particularly dry habitat they occupy. Climatic variables associated with habitat suitability suggest the southern cluster has affinity for the arid and semiarid conditions present in its distribution. Conservation measures should consider the genetic structure observed and differences in climatic spaces to maintain the evolutionary potential of the species.

Dimensionality reduction distills complex evolutionary relationships in seasonal influenza and SARS-CoV-2.

Public health researchers and practitioners commonly infer phylogenies from viral genome sequences to understand transmission dynamics and identify clusters of genetically-related samples. However, viruses that reassort or recombine violate phylogenetic assumptions and require more sophisticated methods. Even when phylogenies are appropriate, they can be unnecessary or difficult to interpret without specialty knowledge. For example, pairwise distances between sequences can be enough to identify clusters of related samples or assign new samples to existing phylogenetic clusters. In this work, we tested whether dimensionality reduction methods could capture known genetic groups within two human pathogenic viruses that cause substantial human morbidity and mortality and frequently reassort or recombine, respectively: seasonal influenza A/H3N2 and SARS-CoV-2. We applied principal component analysis (PCA), multidimensional scaling (MDS), t-distributed stochastic neighbor embedding (t-SNE), and uniform manifold approximation and projection (UMAP) to sequences with well-defined phylogenetic clades and either reassortment (H3N2) or recombination (SARS-CoV-2). For each low-dimensional embedding of sequences, we calculated the correlation between pairwise genetic and Euclidean distances in the embedding and applied a hierarchical clustering method to identify clusters in the embedding. We measured the accuracy of clusters compared to previously defined phylogenetic clades, reassortment clusters, or recombinant lineages. We found that MDS embeddings accurately represented pairwise genetic distances including the intermediate placement of recombinant SARS-CoV-2 lineages between parental lineages. Clusters from t-SNE embeddings accurately recapitulated known phylogenetic clades, H3N2 reassortment groups, and SARS-CoV-2 recombinant lineages. We show that simple statistical methods without a biological model can accurately represent known genetic relationships for relevant human pathogenic viruses. Our open source implementation of these methods for analysis of viral genome sequences can be easily applied when phylogenetic methods are either unnecessary or inappropriate.

Genetic diversity of apple heirloom germplasm in Bosnia and Herzegovina, as revealed by SNP markers

The cultivated apple (Malus domestica Borkh.) is an economically important fruit crop in countries worldwide, including Bosnia and Herzegovina (BIH).The gene bank activities in BIH were initiated in the 1930s and continued until the war in the 1990s, when much of the documentation was lost. Since then, uncoordinated efforts were made to establish apple collections in different regions, but a comprehensive analysis of genetic resources was lacking. This prompted the current study where we present the first thorough overview of the national genetic resources of BIH apples. Thus, we analyzed 165 accessions in the apple gene bank at the Institute for Genetic Resources (IGR) established at Banja Luka using the 20 K apple Infinium® single nucleotide polymorphism (SNP) array. We combined the results with previously published data on the germplasm collections at Srebrenik and Goražde, genotyped using the Axiom® Apple 480 K SNP array. In total, 234 accessions were included in the study of which 220 were presumed to be local cultivars and 14 were known international reference cultivars. We identified numerous genotypic duplicates within and between collections and suggested preferred names to be used in the future. We found the BIH germplasm to have relatively few parent-offspring relationships, particularly among local cultivars, which might reflect the country’s history and patterns of apple cultivar introduction. A number of cultivars unique to BIH and a weakly defined genetic group were identified via STRUCTURE analysis, representing interesting targets for future research and preservation efforts.

PCR Detection of Bartonella spp. and Borreliella spp. DNA in Dry Blood Spot Samples from Human Patients.

Lyme disease is the most commonly reported vector-borne disease in the United States. Bartonella constitute an additional zoonotic pathogen whose public health impact and diversity continue to emerge. Rapid, sensitive, and specific detection of these and other vector-borne pathogens remains challenging, especially for patients with persistent infections. This report describes an approach for DNA extraction and PCR testing for the detection of Bartonella spp. and Borreliella spp. from dry blood spot (DBS) specimens from human patients. The present study included extraction of DNA and PCR testing of DBS samples from 105 patients with poorly defined, chronic symptoms labeled as Lyme-Like Syndromic Illness (LLSI). Bartonella spp. DNA was detected in 20/105 (19%) and Borreliella spp. DNA was detected in 41/105 (39%) patients with LLSI. Neither group of organisms was detected in DBS samples from 42 healthy control subjects. Bartonella spp. 16S-23S rRNA internal transcribed spacer sequences were highly similar to ones previously identified in yellow flies, lone star ticks, a human patient from Florida, mosquitoes in Europe, or B. apihabitans and choladocola strains from honeybees. These human strains may represent new genetic strains or groups of human pathogenic species of Bartonella. The 41 Borreliella spp. flaB gene sequences obtained from human patients suggested the presence of four different species, including B. burgdorferi, B. americana, B. andersonii, and B. bissettiae/carolinensis-like strains. These results suggest that specific aspects of the DBS DNA extraction and PCR approach enabled the detection of Bartonella spp. and Borreliella spp. DNA from very small amounts of human whole blood from some patients, including specimens stored on filter paper for 17 years.

Neuronal Remodelling as a Predictor of Autism Spectrum Disorder Diagnosis

People with Autism Spectrum Disorder (ASD) are a neurodevelopmental symptom group characterized by significant deficits in information connectivity, mainly caused by specific genetic mutations affecting the fluency of the gamma-aminobutyric acid (GABAergic) system. This disruption, to a greater or lesser degree, hinders the interactive process of incoming stimuli with previously stored information, preventing working memory from fulfilling its role of facilitating access to information in permanent memory and later recovery. In addition to the genetic components, environmental processes occurring, above all, in early childhood, related to specific organic and severe psycho-emotional diseases can produce the same effects in the brain system as the genetic karyotypic component through the concept of neuronal remodelling. In this sense, this research aims to empirically show the influence of neuronal remodelling on the GABAergic pathway leading to the traits of autism spectrum behaviour. A total of 175 participants from the three levels of ASD intensity have participated in this study. Data have been analysed through Linear Logistic Regression, which shows that both components, the genetic process and the environmental process, significantly influence the neural connective pathway that relates information, unlike other operationalized covariates, such as gender or age of the participants. Likewise, as shown by the Chi-Square Test, the interactions between genetic and environmental variables showed no differences in their interaction regarding the connectivity level that would explain the different levels of disorder. However, when there is a combination of genetic mutations in the diagnostic karyotype, there are significant differences between the genetic group and the environmental process over the neural network.

Valency patterns in Mande

Abstract In this paper, we address valency patterns in seven Mande languages with various degrees of genealogical proximity. Our study is based on the BivalTyp questionnaire focusing on 130 two-place predicates (Say 2020). While belonging to two distinct genetic groupings, two languages of the set, i.e. Mano (Southern Mande) and Kpelle (Southwestern Mande), are in intense contact with one another. We found that although Mano verbal stems are virtually unaffected by contact, the patterns of valency expression, including construction types and choice of postposition, but also the semantics of complex verbs are strongly influenced by Kpelle. This study thus adds further evidence for the predominance of pattern borrowing in multilingual settings.

Whole Genome Sequences of Cryptotympana Atrata Fabricius, 1775 (Hemiptera: Cicadidae) in the Korean Peninsula: Insights into Population Structure with Novel Pathogenic Or Symbiotic Candidates

Background: The blackish cicada (Cryptotympana atrata) exhibits unique characteristics and is one of the model cicadas found in the Korean Peninsula. It is a species of southern origin, prefers high temperatures, and is listed as a climate-sensitive indicator species in South Korea. Therefore, this species can be utilized to study the impact of climate change on the genetic diversity and structure of populations. However, research on the genome of C. atrata is limited. Methods: We sequenced the genome of an individual collected from South Korea and constructed a draft genome. Additionally, we collected ten specimens from each of the five regions in South Korea and identified single nucleotide variants (SNVs) for population genetic analysis. The sequencing library was constructed using the MGIEasy DNA Library Prep Kit and sequenced using the MGISEQ-2000 platform with 150-bp paired-end reads. Results: The draft genome of C. atrata was approximately 5.0 Gb or 5.2 Gb, making it one of the largest genomes among insects. Population genetic analysis, which was conducted on four populations in South Korea, including both previously distributed and newly expanded regions, showed that Jeju Island, a remote southern island with the highest average temperature, formed an independent genetic group. However, there were no notable genetic differences among the inland populations selected based on varying average temperatures, indicating that the current population genetic composition on the Korean Peninsula is more reflective of biogeographic history rather than climate- induced genetic structures. Additionally, we unexpectedly observed that most individuals of C. atrata collected in a specific locality were infected with microbes not commonly found in insects, necessitating further research on the pathogens within C. atrata. Conclusion: This study introduces the draft genome of C. atrata, a climate-sensitive indicator species in South Korea. Population analysis results indicate that the current genetic structure of C. atrata is driven by biogeographic history rather than just climate. The prevalence of widespread pathogen infections raises concerns about their impact on C. atrata. Considering the scarcity of publicly available genomic resources related to the family Cicadidae, this draft genome and population data of C. atrata are expected to serve as a valuable resource for various studies utilizing cicada genomes.

Pollinator shifts despite hybridisation in the Cape's hyperdiverse heathers (Erica, Ericaceae).

Interrogating the ecological and geographic factors that influence population divergence dynamics can reveal why some groups of organisms diversify more prolifically than others. One such group is the heathers (Erica, Ericaceae), the largest plant genus in the Cape Floristic Region. We study Erica abietina, a highly variable species complex with four subspecies differing in geographic range, habitat and pollination syndrome. We test for population differentiation, hybridisation, introgression and pollinator-driven divergence using genotyping-by-sequencing on samples across the entire distribution. We find five variably distinct genetic groups, with one subspecies comprising two independent lineages that are geographically isolated and occur on different soil types. Phylogenetic analysis suggests two independent shifts between bird and insect pollination, with accompanying genetic divergence. However, for one pair of populations with different pollinators, we uncover several individuals of hybrid origin at a site of sympatry. These results suggest that floral differentiation driven by divergent selection acts in concert with geographic isolation to maintain reproductive isolation and promote speciation. Our investigations reveal a highly dynamic system whose diversity has been shaped by a variety of interacting forces. We suggest that such a system could be a model for much of the diversification of the Cape flora.

Improving genetic risk modeling of dementia from real-world data in underrepresented populations

Genetic risk modeling for dementia offers significant benefits, but studies based on real-world data, particularly for underrepresented populations, are limited. We employ an Elastic Net model for dementia risk prediction using single-nucleotide polymorphisms prioritized by functional genomic data from multiple neurodegenerative disease genome-wide association studies. We compare this model with APOE and polygenic risk score models across genetic ancestry groups (Hispanic Latino American sample: 610 patients with 126 cases; African American sample: 440 patients with 84 cases; East Asian American sample: 673 patients with 75 cases), using electronic health records from UCLA Health for discovery and the All of Us cohort for validation. Our model significantly outperforms other models across multiple ancestries, improving the area-under-precision-recall curve by 31–84% (Wilcoxon signed-rank test p-value <0.05) and the area-under-the-receiver-operating characteristic by 11–17% (DeLong test p-value <0.05) compared to the APOE and the polygenic risk score models. We identify shared and ancestry-specific risk genes and biological pathways, reinforcing and adding to existing knowledge. Our study highlights the benefits of integrating functional mapping, multiple neurodegenerative diseases, and machine learning for genetic risk models in diverse populations. Our findings hold potential for refining precision medicine strategies in dementia diagnosis.

Genetic diversity and population structure of Plenodomus biglobosus on flixweed (Descurainia sophia) in northwestern China.

Plenodomus biglobosus (Pb), a causal agent of blackleg of rapeseed, is composed of several subspecies, including 'australensis' (Pba), 'brassicae' (Pbb) and 'canadensis' (Pbc). Besides rapeseed, Pb can infect many wild cruciferous plants (WCPs), such as flixweed (Descurainiasophia) and pennycress (Thlaspi arvense), which may become the infection source for blackleg of rapeseed. However, Pb on WCPs has not been well investigated in China. This study identified the blackleg fungi on two WCPs in Sayram Lake and Zhaosu County in Xinjiang of China: flixweed (15 isolates) and pennycress (1 isolate) as well as on rapeseed (971 isolates). They belonged to Pba (11), Pbb (18) and Pbc (958). Pba occurred on flixweed (10) and pennycress (1) only in Sayram Lake, whereas Pbb and Pbc occurred on flixweed (1 and 4 isolates, respectively) and rapeseed (17 and 954 isolates, respectively) in Zhaosu County. Then, virulence of 16 isolates from flixweed and pennycress was determined on rapeseed. Their genomes were sequenced and used to identify the mating-type idiomorphs and to analyze population genetic structure. Results showed that all of the 16 isolates were virulent to rapeseed. Only MAT1-1 was detected in 11 Pba isolates, implying that Pba may lack sexual reproduction. The 16 isolates from two WCPs were divided into four genetic groups: Group I for Pbc (4 isolates), Group II for Pbb (1 isolate), and Group III (3 isolates) and IV (8 isolates) for Pba. The findings about the single mating-type in Pba and its limited geographic distribution provided a case showing the importance of sexual reproduction in epidemics of Pb. To the best of our knowledge, this is the first report of Pba, Pbb and Pbc on flixweed, and Pba on pennycress in China.

Exploring Genetic Variability and Morpho-Agronomic Trait Associations Among Ethiopian Flax (Linum Usitatissimum L.) Accessions for Enhanced Fiber and Seed Yield

ABSTRACT Flax is a versatile crop grown for its fiber and seed oil. Despite extensive conservation efforts in Ethiopia, the genetic potential of flax accessions conserved in the gene bank remains largely underexplored for fiber and seed yield. Here, we aimed to assess the genetic variability and association of morpho-agronomic traits and identify potential accessions for fiber and seed yield among 150 flax accessions. The study was conducted at Holeta Agricultural Research Center during 2022/23 growing season using an augmented design. Data were collected on flowering and maturity dates, plant and technical height, basal and secondary branch, boll and seed numbers, 1000-seed weight, and yield. Results revealed significant variation both between blocks and within treatments, with flowering time, maturity, plant height, boll number, seed weight, and yield contributing for the highest variability (58.7%). Cluster analysis revealed nine distinct genetic groups, each exhibiting specific trait patterns. Seed yield had strong associations with maturity, plant height, and boll number. High broad-sense heritability for days to flowering, plant height, and yield traits suggests selection could be effective based on phenotypic expressions. The study highlights the potential of Ethiopian flax genetic diversity for enhancing fiber and seed yield, suggesting effective selection based on key traits.

The Human Monkeypox Virus and Host Immunity: Emerging Diagnostic and Therapeutic Challenges.

This article explores the Human Monkeypox Virus (MPV), a contagious virus that causes disease in both vertebrates and insects. It originated in Denmark in 1958 and expanded beyond Africa during the 1970s. The virus was initially detected in the United States in 2003 following the hospitalisation of a toddler who had been bitten by a prairie dog. The article examines the identification of the virus, its categorization into two genetic groups with dif-ferent levels of harmfulness, and its genetic changes over time due to specific influences. Additionally, it investigates the immunological reaction to MPXV, encompassing both the innate and adaptive systems. The essay also addresses the diagnostic difficulties presented by MPXV's resemblance to other orthopoxviruses and the progress made in molecular diagnos-tics. The paper analyses different therapeutic interventions, such as tecovirimat, an antiviral medication, and JYNNEOS, a vaccine, in terms of their efficacy, potential drawbacks, and the difficulties encountered in managing outbreaks. The future outlook emphasises the ne-cessity of inventive research methodologies, worldwide monitoring, and individualised med-ical treatments to counteract the dissemination of MPXV and alleviate its consequences on public health.

Germline RAD51C and RAD51D Mutations in High-Risk Chinese Breast and/or Ovarian Cancer Patients and Families.

RAD51C and RAD51D are crucial in homologous recombination (HR) DNA repair. The prevalence of the RAD51C and RAD51D mutations in breast cancer varies across ethnic groups. Associations of RAD51C and RAD51D germline pathogenic variants (GPVs) with breast and ovarian cancer predisposition have been recently reported and are of interest. We performed multi-gene panel sequencing to study the prevalence of RAD51C and RAD51D germline mutations among 3728 patients with hereditary breast and/or ovarian cancer (HBOC). We identified 18 pathogenic RAD51C and RAD51D mutation carriers, with a mutation frequency of 0.13% (5/3728) and 0.35% (13/3728), respectively. The most common recurrent mutation was RAD51D c.270_271dupTA; p.(Lys91Ilefs*13), with a mutation frequency of 0.30% (11/3728), which was also commonly identified in Asians. Only four out of six cases (66.7%) of this common mutation tested positive for homologous recombination deficiency (HRD). Taking the family studies in our registry and tumor molecular pathology together, we concluded that this relatively common RAD51D variant showed incomplete penetrance in our local Chinese community. Personalized genetic counseling emphasizing family history for families with this variant, as suggested at the UK Cancer Genetics Group (UKCGG) Consensus meeting, would also be appropriate in Chinese families.

Impact of Dietary Isoflavones in Standard Chow on Reproductive Development in Juvenile and Adult Female Mice with Different Metabolic Phenotypes.

Two factors influencing female reproduction have been repeatedly studied in different animal species and humans, namely, 1. secondary plant compounds, especially phytoestrogens (mainly isoflavones (IFs)), and 2. the physical constitution/metabolic phenotype (e.g., obesity). So far, these research results have only been considered separately. In this study, we investigated the influence on reproduction of both phytochemicals, mainly dietary IFs, and the metabolic phenotype represented by three mouse models considered as three distinct genetic groups (a control group, a mouse model with high metabolic activity, and a mouse line with obese body weight). The IF content in different investigated standard chows with similar macronutrient profiles varied significantly (p < 0.005), leading to high mean total plasma IF levels of up to 5.8 µmol/L in juvenile and 6.7 µmol/L in adult female mice. Reproductive performance was only slightly affected; only an IF dose-dependent effect on gestation length was observed in all genetic groups, as well as an effect on pregnancy rate in obese mice. Dietary IF exposure, however, caused earlier onset of vaginal opening by 4-10 days in juvenile mice (p < 0.05), dependent on the genetic group, resulting in a slight acceleration of sexual maturation in the already precocious obese model and to a strong earlier maturation in the otherwise late-maturing sporty model, bred for high treadmill performance. Therefore, our results may help to draw the missing line between the effect of dietary secondary plant constituents, such as IFs, and metabolic phenotype on sexual development.

Copy-number variants differ in frequency across genetic ancestry groups

Copy-number variants (CNVs) have been implicated in a variety of neuropsychiatric and cognitive phenotypes. We found that deleterious CNVs are less prevalent in non-European ancestry groups than they are in European ancestry groups of both the UK Biobank (UKBB) and a US replication cohort (SPARK). We also identified specific recurrent CNVs that consistently differ in frequency across ancestry groups in both the UKBB and SPARK. These ancestry-related differences in CNV prevalence present in both an unselected community population and a family cohort enriched with individuals diagnosed with autism spectrum disorder (ASD) strongly suggest that genetic ancestry should be considered when probing associations between CNVs and health outcomes.

Comparative Chloroplast Genomes Analysis Provided Adaptive Evolution Insights in Medicago ruthenica.

A perennial leguminous forage, Medicago ruthenica has outstanding tolerance to abiotic stresses. The genome of Medicago ruthenica is large and has a complex genetic background, making it challenging to accurately determine genetic information. However, the chloroplast genome is widely used for researching issues related to evolution, genetic diversity, and other studies. To better understand its chloroplast characteristics and adaptive evolution, chloroplast genomes of 61 Medicago ruthenica were assembled (including 16 cultivated Medicago ruthenica germplasm and 45 wild Medicago ruthenica germplasm). These were used to construct the pan-chloroplast genome of Medicago ruthenica, and the chloroplast genomes of cultivated and wild Medicago ruthenica were compared and analyzed. Phylogenetic and haplotype analyses revealed two main clades of 61 Medicago ruthenica germplasm chloroplast genomes, distributed in eastern and western regions. Meanwhile, based on chloroplast variation information, 61 Medicago ruthenica germplasm can be divided into three genetic groups. Unlike the phylogenetic tree constructed from the chloroplast genome, a new intermediate group has been identified, mainly consisting of samples from the eastern region of Inner Mongolia, Shanxi Province, and Hebei Province. Transcriptomic analysis showed that 29 genes were upregulated and three genes were downregulated. The analysis of these genes mainly focuses on enhancing plant resilience and adapting adversity by stabilizing the photosystem structure and promoting protein synthesis. Additionally, in the analysis of adaptive evolution, the accD, clpP and ycf1 genes showed higher average Ka/Ks ratios and exhibited significant nucleotide diversity, indicating that these genes are strongly positively selected. The editing efficiency of the ycf1 and clpP genes significantly increases under abiotic stress, which may positively contribute to plant adaptation to the environment. In conclusion, the construction and comparative analysis of the complete chloroplast genomes of 61 Medicago ruthenica germplasm from different regions not only revealed new insights into the genetic variation and phylogenetic relationships of Medicago ruthenica germplasm, but also highlighted the importance of chloroplast transcriptome analysis in elucidating the model of chloroplast responses to abiotic stress. These provide valuable information for further research on the adaptive evolution of Medicago ruthenica.

Air pollutants, genetic susceptibility and the risk of schizophrenia: large prospective study.

Evidence linking air pollutants and the risk of schizophrenia remains limited and inconsistent, and no studies have investigated the joint effect of air pollutant exposure and genetic factors on schizophrenia risk. To investigate how exposure to air pollution affects schizophrenia risk and the potential effect modification of genetic susceptibility. Our study was conducted using data on 485 288 participants from the UK Biobank. Cox proportional hazards models were used to estimate the schizophrenia risk as a function of long-term air pollution exposure presented as a time-varying variable. We also derived the schizophrenia polygenic risk score (PRS) utilising data provided by the UK Biobank, and investigated the modification effect of genetic susceptibility. During a median follow-up period of 11.9 years, 417 individuals developed schizophrenia (mean age 55.57 years, s.d. = 8.68; 45.6% female). Significant correlations were observed between long-term exposure to four air pollutants (PM2.5; PM10; nitrogen oxides, NOx; nitrogen dioxide, NO2) and the schizophrenia risk in each genetic risk group. Interactions between genetic factors and the pollutants NO2 and NOx had an effect on schizophrenia events. Compared with those with low PRS and low air pollution, participants with high PRS and high air pollution had the highest risk of incident schizophrenia (PM2.5: hazard ratio = 6.25 (95% CI 5.03-7.76); PM10: hazard ratio = 7.38 (95% CI 5.86-9.29); NO2: hazard ratio = 6.31 (95% CI 5.02-7.93); NOx: hazard ratio = 6.62 (95% CI 5.24-8.37)). Long-term exposure to air pollutants was positively related to the schizophrenia risk. Furthermore, high genetic susceptibility could increase the effect of NO2 and NOx on schizophrenia risk.

Research note: differential heterosis of spent laying hens’ carcass characteristics and meat quality in reciprocal crosses between White Leghorn and Beijing-You chickens

Hybridization is used extensively in commercial layer production. However, heterosis for carcass performance and meat quality of spent laying hens remains unclear, especially under the trend of extended laying cycles. In this study, indigenous Beijing-You chickens (Y) and elite White Leghorn layers (W) were selected to generate purebreds (WW and YY) and reciprocal crosses (WY and YW). Data on traits including carcass compositions, meat quality, and main nutrients for breast muscle were collected when chickens fed to 100 wks of age. Results showed that body weight (BW) and dressed weight for WY and YW with positive heterosis were significantly higher than WW (P < 0.05). YW had the heaviest breast and thigh of 232.28 g and 278.48 g, respectively. The abdominal fat weight for WY and YW were greatly higher than that for WW (P > 0.05). The yields of carcass compositions, including the dressed yield, half eviscerated yield, eviscerated yield, breast yield and thigh yield, did not differ among four genetic groups (P > 0.05), except for the yield of abdominal fat. The largest heterosis differences appeared in breast weight (12.26% in YW v.s. -0.46% in WY) and abdominal fat yield (15.26% in YW v.s. 24.55% in WY). Although BW for crossbreds were similar, the specific parts of the carcass between them were different. For meat quality, WY had negative heterosis (P < 0.05) with the lowest lightness and yellowness, whereas YW had the completely opposite trend. Neither pH1h nor pH24h values had difference among purebreds and reciprocal crossbreds (P > 0.05). The drip loss and cooking loss were 4.01%-4.77% and 15.59%-21.31% respectively among four genetic groups. The main nutrients of breast, including moisture, crude protein, intramuscular fat and unsaturated fatty acid, did not differ for purebreds and crossbreds (P > 0.05), except for saturated fatty acid. In general, the crossbreds even at the later laying period still showed divergent heterosis on carcass performance and meat characteristics. In view of the heterosis, Beijing-You chickens can use as the sire line in the crossbreeding to improve carcass compositions of spent hens.

Carcass and Meat Characteristics of Cull Heifers from Different Genetic Groups Fed Diets with Different Sources of Nonprotein Nitrogen in Confinement.

The aim of this study was to evaluate the effect of genetic groups and diets with different sources of nonprotein nitrogen (NPN) on the carcass and meat characteristics of beef heifers. The meat from 40 heifers (20 ½ Angus ½ Nellore (A × N) and 20 ½ Charolais ½ Nellore (L × N)), finished in feedlots, was used. The heifers were fed diets containing different sources of NPN-(1) a diet with livestock urea and protected urea (LPU) and (2) a diet with extruded urea (EU)-in a completely randomized design with a 2 × 2 factorial arrangement. Carcass, composition and meat quality evaluations were carried out. There were no significant interactions between diet and genetic group for most of the variables evaluated (p > 0.05). The A × N heifers had higher hot carcass weights (305.73 vs. 279.80 kg), loin eye areas (80.87 vs. 75.45 cm2), subcutaneous fat thicknesses (8.69 vs. 6.35 mm) and lower shear forces (6.98 vs. 7.7 kg) compared to the C × N heifers (p < 0.05). The meat from the A × N heifers had higher proportions of saturated fatty acids (49.41 vs. 47.95%), with no effects on the proportions of monounsaturated (47.57%) and polyunsaturated (4.01%) fatty acids. The A × N heifers had better carcass and meat characteristics, while the C × N heifers had meat and fat with better fatty acid profiles.