Domestic Strains Research Articles

Phenotyping of a new yeast mapping population reveals differences in the activation of the TORC1 signalling pathway between wild and domesticated yeast strains

Domestication can be understood as a symbiotic relationship that benefits both domesticator and domesticated species, involving multiple genetic changes that configure the phenotype of the domesticated species. One of the most important domesticated species is the yeast Saccharomyces cerevisiae, with both domesticated strains used for different fermentations processes for thousands of years and wild strains existing only in environments without human intervention; however, little is known about the phenotypic effects associated with its domestication. In the present work, we studied the effect of domestication on yeast TORC1 activation, a pleiotropic signalling pathway conserved across the eukaryotic domain. To achieve this goal, we improved a previously generated methodology to assess TORC1 activation, which turned out to be as effective as the original one but also presents several practical advantages for its application (such as facilitating confirmation of transformants and putting the Luc reporter gene under the control of the same PRPL26A promoter for each transformed strain). We then generated a mapping population, the so-called TOMAN-G population, derived from the “1002 Yeast Genomes Project” population, the most comprehensive catalogue of the genetic variation in yeasts. Finally, strains belonging to the TOMAN-G population were phenotyped for TORC1 activation, and then we compared the results obtained between yeast strains with different ecological origins, finding differences in TORC1 activation between wild and domesticated strains, particularly wine strains. These results are indicative of the effect of domestication on TORC1 activation, specifically that the different evolutionary trajectories of wild and domesticated strains have in fact caused differences in the activation of this pathway; furthermore, the phenotypic data obtained in this work could be used to continue underlying the genetic bases of TORC1 activation, a process that is still not fully understood, using techniques such as GWAS to search for specific genetic variants underlying the observed phenotypic variability and phylogenetic tree inferences to gain insight into the evolutionary relationships between these genetic variants.

Two novel sites determine genetic relationships between CPV-2 and FPV: an epidemiological survey of canine and feline parvoviruses in Changchun, China (2020)

Canine parvovirus (CPV-2) and feline parvovirus (FPV) cause severe hemorrhagic diarrhea disease in dogs, cats, and fur-bearing and wildlife carnivores worldwide, continuing to pose significant threats. In this study, 140 rectal swabs were collected from 70 domestic dogs and 70 cats with clinical diarrhea in veterinary clinics in Changchun during 2020. A total of 64.3% (45/70) of dogs and 55.7% (39/70) of cats tested positive for CPV-2 or FPV using colloidal gold strips. Amino acid (aa) sequence alignment of the VP2 protein from 39 CPV-2 and 36 FPV samples revealed that 79.5% (31/39) were CPV-2c, 17.9% (7/39) were a new CPV-2a, and 2.6% (1/39) were mink enteritis virus (MEV). and 8.3% (3/36) FPV from the cats was infected by CPV-2, which suggested that CPV-2c was the dominant variant in dogs and FPV was the major pathogen in cats in Changchun city. Phylogenetic relationships of VP2 genes showed that 26 parvoviruses were closely related to domestic strains previously published in China; however, 8 FPVs and CPV-JL-15/China/2020 were clustered in the lineage of South Asiatic and European countries, and 7 out of 8 FPVs were close to Italy. In addition to Q247H, I248Y, F544Y, and E/V545V/K, two novel site mutations of N23D or L630P in NS1 protein, associated with viral cross-species transmissions, were first found as a reminder of genetic relationships of CPV-2 variants and FPVs in the same branch. Thus, regular and massive virus surveillance of parvovirus is necessary to cope with its ongoing infection, circulation, mutations, and evolutions to new subtypes with strong survival abilities.

Pan-genome analysis reveals genomic variations during enoki mushroom domestication, with emphasis on genetic signatures of cap color and stipe length

IntroductionThe domestication of edible mushrooms, including Flammulina filiformis, offers valuable insights into the genetic changes driven by artificial selection. Understanding these changes is crucial for uncovering the mechanisms behind genome evolution in domesticated mushrooms. ObjectivesThis study aims to investigate the population structure, genetic diversity, and domestication-related genomic changes in F. filiformis. By comparing the genome sequences of 199 wild and cultivated strains, we aim to elucidate the impact of domestication on F. filiformis. MethodsWe performed de novo genome assembly and gene-based pan-genome analysis on the 199 strains, which included both wild and cultivated strains. We also conducted genome-wide association studies (GWAS) using presence-absence variation (PAV) and SNP data, combined with RNA sequencing, to identify genes associated with domestication traits, such as cap color and stalk length. Gene functional confirmation was achieved through genetic transformation experiments. ResultsOur analysis grouped the strains into four distinct populations, which correlated with varying intensities of artificial selection. The three cultivated populations exhibited smaller genome sizes, fewer genes, lower genetic variation, reduced gene expression diversity, and lower heterozygosity compared to the wild population. The analysis revealed the loss of genes related to the beta-lactam antibiotic catabolic process and specific MAPK pathway genes during domestication, rendering domesticated strains more susceptible to diseases. Four genes closely associated with cap color and stipe length were identified, but genetic transformation experiments confirmed the functional relevance of only two (FfB and FfD) identified through PAV-based GWAS. ConclusionThis study uncovered significant genomic variations between cultivated and wild Flammulina filiformis populations, including the loss of pathogen resistance genes during domestication. We also identified key genes linked to cap color and stipe length, demonstrating for the first time the important role of PAV variation in mushroom domestication. These insights provide a foundation for future mushroom breeding and evolutionary research.

Transcriptome analysis reveals the importance of phototransduction during the first-feeding in mandarin fish (Siniperca chuatsi).

The mandarin fish (Siniperca chuatsi), as a typical freshwater carnivorous fish, has high economic value. Mandarin fish have a peculiar feeding habit of feeding on other live fry during the first-feeding period, while rejecting zooplankton or particulate feed, which may be attributed to the low expression of zooplankton-associated gene sws1 in mandarin fish. The domesticated strain of mandarin fish could feed on Artemia at 3 days post hatching (dph). However, the mechanism of mandarin fish larvae recognize and forage Artemia as food is still unclear. In this study, we employed transcriptional analysis to identify the representative differential pathways between mandarin fish larvae unfed and fed with Artemia at 3 dph. The comparative transcriptome analysis has unveiled a tapestry of genetic expression, highlighting 403 genes that have been up-regulated and 259 that have been down-regulated, all of which constitute the differentially expressed genes (DEGs). KEGG pathway analysis revealed that the number of differentially expressed genes in the photoconductive signaling pathway was the largest. Next, the Vorinostat (suberoylanilide hydroxamic acid, SAHA) was used to assess whether sws1 induced ingestion of Artemia in mandarin fish larvae. We discovered that SAHA-treated larvae had more food intake of Artemia and up-regulated the transcription level of npy, which might have been associated with the up-regulated of sws1 opsin. Additionally, exposure to 0.5 µM SAHA increased the expression of genes involved in phototransduction pathway. These findings would provide insights on the molecular processes involved in mandarin fish larvae feeding on Artemia at the first-feeding stage.

Endemic maintenance of human-related hepatitis E virus strains in synurbic wild boars, Barcelona Metropolitan Area, Spain

Hepatitis E virus (HEV), shared by humans, domestic animals, and wildlife, is an emerging global public health threat. Because wild boars are a major reservoir of HEV, the new zoonotic interfaces resulting from wild boar population increase and synurbization significantly contribute to increasing the risk of zoonotic transmission of HEV.This study characterizes HEV strains of synurbic wild boars and assesses their relationship with sympatric human and domestic swine HEV strains. We analyzed the faeces of 312 synurbic wild boars collected from 2016 to 2021 in the Barcelona Metropolitan Area (BMA), where there is a high density of wild boars, and found 7 HEV-positive samples among those collected between 2019 and 2020. The molecular analysis of these isolates, along with 6 additional wild boar HEV isolates from a previous study, allowed us to establish a close phylogenetic relationship between these HEV strains and human HEV isolates from sympatric blood donors and domestic pigs from Catalonia. HEV-positive wild boar samples belonged to piglet, juvenile and yearling individuals, but not adults, indicating the endemic maintenance of HEV in the wild boar population of the BMA by naïve young individuals. All wild boar HEV isolates in this study classified within HEV genotype 3.The results show, for the first time, a close molecular similarity between the HEV strains endemically maintained by the synurbic wild boars in the BMA and citizens from the same area and period. The data could also indicate that HEV infection presents a seasonal and interannual variability in wild boars of BMA. Further investigation is required to unveil the HEV transmission routes between synurbic wild boars and sympatric citizens. These findings can serve in other synurbic wildlife-human interfaces throughout the world.

The distribution of beneficial mutational effects between two sister yeast species poorly explains natural outcomes of vineyard adaptation.

Domesticated strains of Saccharomyces cerevisiae have adapted to resist copper and sulfite, two chemical stressors commonly used in winemaking. S. paradoxus has not adapted to these chemicals despite being consistently present in sympatry with S. cerevisiae in vineyards. This contrast could be driven by a number of factors including niche differences or differential access to resistance mutations between species. In this study, we used a comparative mutagenesis approach to test whether S. paradoxus is mutationally constrained with respect to acquiring greater copper and sulfite resistance. For both species, we assayed the rate, effect size, and pleiotropic costs of resistance mutations and sequenced a subset of 150 mutants. We found that the distributions of mutational effects displayed by the two species were similar and poorly explained the natural pattern. We also found that chromosome VIII aneuploidy and loss of function mutations in PMA1 confer copper resistance in both species, whereas loss of function mutations in REG1 were only a viable route to copper resistance in S. cerevisiae. We also observed a de novo duplication of the CUP1 gene in S. paradoxus but not in S. cerevisiae. For sulfite, loss of function mutations in RTS1 and KSP1 confer resistance in both species, but mutations in RTS1 have larger effects in S. paradoxus. Our results show that even when available mutations are largely similar, species can differ in the adaptive paths available to them. They also demonstrate that assays of the distribution of mutational effects may lack predictive insight concerning adaptive outcomes.

A domestic strain of Lactobacillus rhamnosus attenuates cognitive deficit and pro-inflammatory cytokine expression in an animal model of Alzheimer’s disease

BackgroundMicrobiome dysbiosis plays a significant role in neuroinflammation and Alzheimer’s disease (AD). Therefore, gut microbiome restoration using appropriate probiotics may be beneficial in alleviating AD features. In this study, we investigated the effects of a domestic strain of Lactobacillus rhamnosus (L. rhamnosus) on spatial memory, and cytokines expression in an inflammation-based AD model. MethodMale Wistar rats were randomly divided into four groups (six animals per group) of control, L. rhamnosus-only, D-galactose (D-gal)-only, and D-gal + L. rhamnosus. Spatial learning and memory were assessed using the Morris water maze test. IL-1β, IL-6, and TNF-α expression levels were measured using Real-Time qPCR. A significance level of 0.05 was used for statistical analysis. ResultsIn contrast to the D-gal + L. rhamnosus-treated group, D-gal only treated group showed impaired memory in MWM test compared to the control group. Additionally, D-gal treatment resulted in an increase in IL-1β and TNF-α levels and a decrease in IL-6 levels, which was not statistically significant. However, the TNF-α level was significantly decreased in D-gal + L. rhamnosus-treated group compared to D-gal-only treated group (P < 0.05). Also, IL-6 level was significantly lower in D-gal + L. rhamnosus-treated group compared to control group (P < 0.05). ConclusionThese results suggest that the domestic L. rhamnosus might positively impact cognitive deficit and neuroinflammation. Further studies are suggested to investigate the specific mechanisms mediating the effects of L. rhamnosus on cognitive functions and neuroinflammation in animal models of AD.

Molecular analysis of canine distemper virus H gene in the golden jackal (Canis aureus) population from Serbia

Canine distemper virus (CDV) is a highly contagious and often fatal disease affecting wild and domesticated carnivores. The virus is a single-stranded RNA virus from the genus Morbillivirus and the family Paramyxoviridae. While domestic dogs are the most common hosts, the virus poses a significant threat to endangered wildlife due to its broad host range. This study aimed to characterize the CDV Haemagglutinin (H) gene in golden jackals and explore the molecular evolution of the virus in an underrepresented host. A total of 88 brain samples from hunted golden jackals were tested for the presence of CDV viral nucleic acid, and the H gene of positive samples was amplified and sequenced using the Sanger method. Phylogenetic analysis, conducted using maximum likelihood methods, revealed that all Serbian sequences clustered within the Arctic lineage. Notably, the analysis identified a tyrosine (Y) at position 549 of the H protein, a mutation commonly associated with wildlife hosts, instead of the histidine (H) typically found in domestic strains. Additionally, a mutation at position 310 was observed, which could potentially affect the protein’s function and virus-host interactions. These findings provide valuable insights into the genetic diversity and evolutionary dynamics of CDV in golden jackals, with broader implications for understanding the virus’s adaptability to different hosts. Further research is needed to investigate the functional impact of these mutations, particularly their role in vaccine efficacy and disease transmission across wildlife and domestic species.

Photoperiodism, testosterone and adult neurogenesis in canaries (Serinus canaria).

Domestic strains of canaries (Serinus canaria) variably respond to photoperiod changes and apparently stay in breeding state for extended periods. Fife Fancy canaries are supposed to be similar to the native species living at 27-39° north where photoperiod significantly changes across the year. Our birds showed reproductive cycles when exposed to light regimes mimicking the annual cycle of photoperiod. However after 6 months in short days (SD: 8L:16D), males developed large testes, as observed by X-ray tomography, and intense singing. Switching to long days (LD: 16L:8D) did not further increase song rate nor testes size but increased song duration, number of syllables per song, and trill occurrence frequency. No sign of regression was observed after 12 weeks in LD but return to SD produced a rapid decrease in testes size and singing activity below values in birds maintained throughout in SD. Fife Fancy thus does not seem to develop absolute but only relative refractoriness. The relatively high singing activity expressed by SD-photosensitive males does not seem to depend on high testosterone (T) concentrations. Singing did not correlate with plasma testosterone (T). Treatment with ATD + Flutamide only marginally decreased song rate and did not affect song quality nor song control nuclei volume. These birds are either supersensitive to low T levels or their reproductive physiology is activated by other mechanisms. Neurogenesis is increased by T and by LD but the function of new neurons incorporated in HVC is poorly understood. We developed a procedure based on X-ray focal irradiation to deplete neural progenitors adjacent to HVC and study the functional consequences. The decrease in neurogenesis increased the variability of T-induced songs in females and decreased their bandwidth. Neurogenesis in HVC thus plays a role in song production and X-ray focal irradiation represents an excellent tool to analyze adult neurogenesis.

Genome resequencing reveals genetic status of Macrobrachium rosenbergii populations in China

The giant freshwater prawn (Macrobrachium rosenbergii) has been widely cultured in China since 1990s. In this study, 189 individuals were sampled from 10 distinct populations, including original populations introduced from abroad and domesticated strains in China, namely Florida (FD), "Nantaihu No.2" (NT), Vietnam (YN), Sri Lanka (SK), Bangladesh (ML), Thailand (TG), Taiwan (TW), "Shufeng No.1" (SF), Zhengda (ZD) and New Myanmar (NMD). The genetic diversity and population structure of these populations were analyzed based on a dataset of 300,828 genome-wide SNP loci. The population structure analysis showed that the 10 populations shared 4 ancestors, and the domestic populations (i.e., SF, ZD, TW and NT) shared a common ancestor. The phylogenetic analysis showed that the 10 populations were grouped into 4 branches, with all the domestic populations clustering together. Estimation of fixation index (Fst) values revealed relatively lower Fst values among the domestic populations, in contrast to the more significant differences observed between domestic and foreign-origin populations. Gene flow analysis revealed three significant events of genetic exchange among the 10 populations: (1) from YN to the common ancestor of FD, TG and the domestic populations, (2) from NMD to the common ancestor of TG and FD, and (3) from the common ancestor of NMD, YN, ML and SK to ZD population. In addition, selective sweep analysis, utilizing Fst and nucleotide diversity (Pi) estimations, was conducted on representative populations (i.e., ML and SF), and 7 positively selected genes were identified, including Prospero Homeobox 1 (Prox1), Forkhead Box L1 (Foxl1), Tousled Like Kinase 2 (TLK2), G Protein Subunit Alpha 14 (Gna14), Uronyl 2-sulfotransferase (Ust), MAX Network Transcriptional Repressor (Mnt) and Importin-9 (Ipo9). These findings contribute to elucidating the breeding potential of the introduced populations and provide insights into the genetic status of the domestic breeding strains of M. rosenbergii in China.

Molecular mechanism of reduced biological fitness of fludioxonil-resistant strains of Botrytis cinerea based on transcriptome analysis.

Fludioxonil is a fungicide used to control gray mold. However, the frequency of resistance in the field is low, and highly resistant strains are rarely isolated. The biological fitness of the resistant strain is lower than that of the wild strain. Therefore, the molecular mechanism underlying the decrease in the fitness of the fludioxonil-resistant strain of Botrytis cinerea was explored to provide a theoretical basis for resistance monitoring and management. Transcriptome analysis was performed on five different-point mutant resistant strains of fludioxonil, focusing on mining and screening candidate genes that lead to reduced fitness of the resistant strains and the functional verification of these genes. The differentially expressed genes (DEGs) of the five point-mutation resistant strains intersected with 1869 DEGs. Enrichment analysis showed that three downregulated genes (Bcin05g07030, Bcgad1, and Bcin03g05840) were enriched in multiple metabolic pathways and were downregulated in both domesticated strains. Bcin05g07030 and Bcin03g05840 were involved in mycelial growth and development, pathogenicity, and conidial yield, and negatively regulated oxidative stress and cell wall synthesis. Bcgad1 was involved in mycelial growth and development, conidial yield, oxidative stress, and cell wall synthesis. Furthermore, Bcin05g07030 was involved in osmotic stress and spore germination, whereas Bcin03g05840 and Bcgad1 negatively regulated osmotic stress and cell wall integrity. These results enable us to further understand the molecular mechanism underlying the decrease in the biological fitness of B. cinerea fludioxonil-resistant strains. © 2024 Society of Chemical Industry.

Genomic Characterization and Antimicrobial Resistance of Four Mcr-1 Escherichia coli Strains Isolated from Human and Environment Sources, Hainan Province, Tropical China

Background: The rapid spread of multidrug-resistant gram-negative bacteria, particularly the increase in carbapenem-resistant strains, has led to a critical level of resistance in clinical settings. Colistin is considered to be the last line of defense against these gram-negative bacteria. Objectives: This study aims to investigate the genetic characteristics and antimicrobial resistance (AMR) patterns of four mcr-1 (mobile colistin resistance) Escherichia coli isolates from various sources in Hainan Province, tropical China, and to determine their genetic relationships with both domestic and global strains. Methods: Samples were collected from swimming pools, marine beaches, and beach personnel in Haikou and Sanya, Hainan Province, China. E. coli isolates were obtained, multilocus sequence typing was performed, and the mcr family resistance genes were amplified by polymerase chain reaction. The mobile sequences, AMR genes, phenotypes, and virulence genotypes of the mcr-1 strains were analyzed. Phylogenetic analyses were conducted to investigate the relationships between the mcr-1E. coli strains and those in the NCBI database. Results: In the current study, the mcr-1 resistance gene was detected in 4 strains, accounting for 2.94% (4/136) of the total. The 4 strains of E. coli were isolated from a freshwater swimming pool, a pool wall, seawater, and a human body. Among the four strains, the minimum inhibitory concentration of polymyxin was 8 mg/L, except for one strain, which showed low-level resistance at 4 mg/L. All four strains showed complete resistance to ampicillin, three were resistant to compound sulfamethoxazole and chloramphenicol, and all strains were sensitive to other common antibiotics. The virulence genes cfaA, cfaB, cfaC, and cfaD/cfaE were detected in all E. coli strains. The insertable sequence IS3 was the most widely distributed type. Three isolates were identified as ST987, whereas the isolate from marine sources was identified as ST24. Comparison of the core genes of the strains indicated that the four strains were closely related to the Chrysomya sp. from Northern Thailand. Conclusions: The four mcr-1 genes can mediate low to medium levels of colistin resistance, facilitating their dissemination within the population and the environment. It is crucial to trace the source of multidrug-resistant bacteria in recreational water, which is in direct contact with humans, and to reduce the risks to human health through effective supervision.

Insights into the evolution and mechanisms of response to heat stress by whole genome sequencing and comparative proteomics analysis of the domesticated edible mushroom Lepista sordida

ABSTRACT Lepista sordida is a valuable edible mushroom rich in natural bioactive compounds. In the present study, a high-quality whole-genome of a domesticated strain of L. sordida was sequenced, revealing a 40.67 Mb genome in 13 contigs. Phylogenetic analysis revealed that L. sordida is evolutionarily closely related to edible mushroom Lyophyllum decastes and Hypsizygus marmoreus. Heat stress has a significant effect on the yield and quality of mushrooms, but the molecular basis for this is poorly understood in L. sordida. A label-free comparative proteomic analysis was performed under different heat stress conditions. The growth of L. sordida mycelia was inhibited, and nuclear apoptosis occurred under heat stress. Ca2+ and MAPK signaling pathways were found to be involved in heat stress signal transduction. It is hypothesized that the expression of various heat shock proteins plays a crucial role in the response to heat stress. In addition, the components of the ubiquitin-proteasome system and the thioredoxin system were upregulated, preventing the accumulation of misfolded proteins and possibly supporting the response to heat stress. In summary, these results provide a fundamental insight into the evolution and heat stress-responsive mechanisms in L. sordida and may facilitate the breeding of heat-tolerant strains for artificial cultivation.

Vgll3 regulates the timing of puberty in farmed Atlantic salmon, but it does not explain family discordance in male maturation following different smolt production regimes

Atlantic salmon (Salmo salar) farming is moving towards extended periods of land-based production to minimise the time at sea, but this increases the risk of unwanted male sexual maturation. As the timing of puberty is driven by genetics (e.g. vgll3) and the environment, optimising rearing strategies and broodstock management may help alleviate the problem. Subsequently, we used a domesticated strain of vgll3 heterozygous broodstock to produce three all-male half-sibling families using three different production regimes to assess the timing of first puberty. Firstly, “large smolts” were produced in a flow-through system on 13 °C freshwater and constant light from first feeding (day 0) up to 1 kg (day 354). The mean incidence of pubertal males increased from 2% at 30 g, up to 78% at 1 kg. Genetics explained a significant (p < 0.05) amount of the variation, with 93, 71, and 34% of the expected early, intermediate, and late maturing vgll3 genotypes being pubertal on day 354, respectively. In addition, pubertal males in the early vgll3 genotype were found at the first sampling at ≈30 g, while it was not observed in the heterozygous and late genotypes until the fish were ≈90 g and ≈280 g, respectively. Secondly, “post-smolts” were produced by switching half the large smolts to 13 °C seawater at 420 g (day 272) and growing them in tanks to 0.95 kg (day 354). This led to a significant 14% reduction in the total incidence of puberty by day 354 compared to the large smolts. However, the regulation of pubertal timing by vgll3 did not interact with salinity. Thirdly, traditional “under-yearling” smolts were produced using periods of natural or manipulated temperature and photoperiod, followed by transfer to a sea-cage at 150 g in December (day 290) where they stayed for one year until harvest at 4.75 kg (day 648). None of these fish were mature at sea transfer, but 9% were at harvest, with 22, 7, and 2% of the early, intermediate, and late vgll3 genotypes being mature, respectively. When comparing the regimes, family effects outside of vgll3 on the prevalence of sexual maturation were significant for the land-based regimes (family means from 46 to 93% on day 354), but not in sea-cages (family means from 7 to 11% on day 648) and evidence for either vgll3 allele being dominant was mixed. Vgll3 also had minimal effects on body size/growth in any regime/family. In conclusion, i) selecting for the late vgll3 allele is an effective method to delay puberty over a range of production regimes, ii) family effects outside of vgll3 were not consistent across regimes, and iii) using seawater reduced the incidence of precocious puberty during land-based production.

Competitive interactions affect introgression and population viability amidst maladaptive hybridization.

The deliberate release of captive-bred individuals, the accidental escape of domesticated strains, or the invasion of closely related conspecifics into wild populations can all lead to introgressive hybridization, which poses a challenge for conservation and wildlife management. Rates of introgression and the magnitude of associated demographic impacts vary widely across ecological contexts. However, the reasons for this variation remain poorly understood. One rarely considered phenomenon in this context is soft selection, wherein relative trait values determine success in intraspecific competition for a limiting resource. Here we develop an eco-genetic model explicitly focussed on understanding the influence of such competitive interactions on the eco-evolutionary dynamics of wild populations experiencing an influx of foreign/domesticated individuals. The model is applicable to any taxon that experiences natural or human-mediated inputs of locally maladapted genotypes ('intrusion'), in addition to phenotype-dependent competition for a limiting resource (e.g. breeding sites, feeding territories). The effects of both acute and chronic intrusion depended strongly on the relative competitiveness of intruders versus locals. When intruders were competitively inferior, density-dependent regulation limited their reproductive success (ability to compete for limited spawning sites), which prevented strong introgression or population declines from occurring. In contrast, when intruders were competitively superior, this amplified introgression and led to increased maladaptation of the admixed population. This had negative consequences for population size and population viability. The results were sensitive to the intrusion level, the magnitude of reproductive excess, trait heritability and the extent to which intruders were maladapted relative to locals. Our findings draw attention to under-appreciated interactions between phenotype-dependent competitive interactions and maladaptive hybridization, which may be critical to determining the impact captive breeding programmes and domesticated escapees can have on otherwise self-sustaining wild populations.

Comparative study of the growth performance of a domesticated strain of Clarias gariepinus (Burchell, 1822) and a wild strain of Clarias senegalensis (Valenciennes, 1840) using artificial reproduction

Comparative study of the growth performance of a domesticated strain of Clarias gariepinus (Burchell, 1822) and a wild strain of Clarias senegalensis (Valenciennes, 1840) using artificial reproduction

Isolation and identification of a pigeonpox virus strain and study on the integration of reticuloendotheliosis virus sequence.

In order to study the integration of reticuloendotheliosis virus (REV) in pigeonpox virus (PPV), we collected suspected pigeonpox disease material, amplified the 4b core protein gene of PPV, the gp90 gene of REV, and the integrated sequence fragments from the end of the ORF201 segment of PPV to the beginning of the LTR of REV, and sequenced these genes. The results showed that a 4b core protein fragment of 332bp was amplified and identified as pigeonpox virus, which was named SX/TY/LTR 01/2023. Sequence analysis showed that the pigeonpox virus isolate belonged to genotype A2, which was the closest to the domestic CVL strain, with a identity of 99.4%. A band of 1191bp was amplified from the gp90 gene of REV, named SX/TY/PPV-REV01/2023, and sequence analysis indicated that REV belonged to genotype III. The sequence analysis showed that REV belonged to genotype III, and belonged to the same large branch as the domestic isolates JSRD0701 and LNR0801, with 99.3% identity. The integrated sequence fragment was amplified to a band of 637bp, which determined that the REV sequence was integrated in the PPV rather than a mixed infection of the two viruses. This indicates that REV was integrated in this isolation of PPV, suggesting that pigeon farms need to prevent reticuloendotheliosis at the same time when preventing pigeonpox.

The distribution of beneficial mutational effects between two sister yeast species poorly explains natural outcomes of vineyard adaptation.

Domesticated strains of Saccharomyces cerevisiae have adapted to resist copper and sulfite, two chemical stressors commonly used in winemaking. S. paradoxus, has not adapted to these chemicals despite being consistently present in sympatry with S. cerevisiae in vineyards. This contrast represents a case of apparent evolutionary constraints favoring greater adaptive capacity in S. cerevisiae. In this study, we used a comparative mutagenesis approach to test whether S. paradoxus is mutationally constrained with respect to acquiring greater copper and sulfite resistance. For both species, we assayed the rate, effect size, and pleiotropic costs of resistance mutations and sequenced a subset of 150 mutants isolated from our screen. We found that the distributions of mutational effects displayed by the two species were very similar and poorly explained the natural pattern. We also found that chromosome VIII aneuploidy and loss of function mutations in PMA1 confer copper resistance in both species, whereas loss of function mutations in REG1 were only a viable route to copper resistance in S. cerevisiae. We also observed a single de novo duplication of the CUP1 gene in S. paradoxus but none in S. cerevisiae. For sulfite, loss of function mutations in RTS1 and KSP1 confer resistance in both species, but mutations in RTS1 have larger average effects in S. paradoxus. Our results show that even when the distributions of mutational effects are largely similar, species can differ in the adaptive paths available to them. They also demonstrate that assays of the distribution of mutational effects may lack predictive insight concerning adaptive outcomes.

Differential pheromone profile as a contributor to premating isolation between two sympatric sibling fruit fly species.

Bactrocera tryoni (Froggatt) and Bactrocera neohumeralis (Hardy) are sibling fruit fly species that are sympatric over much of their ranges. Premating isolation of these close relatives is thought to be maintained in part by allochrony-mating activity in B. tryoni peaks at dusk, whereas in B. neohumeralis, it peaks earlier in the day. To ascertain whether differences in pheromone composition may also contribute to premating isolation between them, this study used solid-phase microextraction and gas chromatography-mass spectrometry to characterize the rectal gland volatiles of a recently collected and a more domesticated strain of each species. These glands are typical production sites and reservoirs of pheromones in bactrocerans. A total of 120 peaks were detected and 50 were identified. Differences were found in the composition of the rectal gland emissions between the sexes, species, and recently collected versus domesticated strains of each species. The compositional variation included several presence/absence and many quantitative differences. Species and strain differences in males included several relatively small alcohols, esters, and aliphatic amides. Species and strain differences in females also included some of the amides but additionally involved many fatty acid esters and 3 spiroacetals. While the strain differences indicate there is also heritable variation in rectal gland emissions within each species, the species differences imply that compositional differences in pheromones emitted from rectal glands could contribute to the premating isolation between B. tryoni and B. neohumeralis. The changes during domestication could also have significant implications for the efficacy of Sterile Insect Technique control programs.

Evolution Characterization and Pathogenicity of an NADC34-like PRRSV Isolated from Inner Mongolia, China.

Porcine reproductive and respiratory syndrome virus (PRRSV) is a pathogen that causes severe abortions in sows and high piglet mortality, resulting in huge economic losses to the pig industry worldwide. The emerging and novel PRRSV isolates are clinically and biologically important, as there are likely recombination and pathogenic differences among PRRSV genomes. Furthermore, the NADC34-like strain has become a major epidemic strain in some parts of China, but the characterization and pathogenicity of the latest strain in Inner Mongolia have not been reported in detail. In this study, an NADC34-like strain (CHNMGKL1-2304) from Tongliao City, Inner Mongolia was successfully isolated and characterized, and confirmed the pathogenicity in pigs. The phylogenetic tree showed that this strain belonged to sublineage 1.5 and had high homology with the strain JS2021NADC34. There is no recombination between CHNMGKL1-2304 and any other domestic strains. Animal experiments show that the CHNMGKL1-2304 strain is moderately virulent to piglets, which show persistent fever, weight loss and high morbidity but no mortality. The presence of PRRSV nucleic acids was detected in both blood, tissues, nasal and fecal swabs. In addition, obvious pathological changes and positive signals were observed in lung, lymph node, liver and spleen tissues when subjected to hematoxylin-eosin (HE) staining and immunohistochemistry (IHC). This report can provide a basis for epidemiological investigations and subsequent studies of PRRSV.