Bd Genotypes Research Articles

Association of microsatellite genotypes with layer economic traits in a selected strain of Rhode Island Red chicken

Randomly selected 76 pullets of RIR selected strain were screened for microsatellite polymorphs and investigated for their association with layer economic traits. Microsatellite alleles were separated from genomic DNA samples through 3.4% MetaPhor® agarose gel electrophoresis. Data were recorded on age at first egg (AFE), egg weights and egg production (EP) at certain age. Microsatellite analysis revealed nine polymorphic loci (EW) and genotypes at ADL0020 locus were significantly associated with EP at 40 and 64 weeks of age, CC (110 bp/110 bp) genotype had the highest EP, whereas, AD (126 bp/102 bp) and BD (118 bp/102 bp) genotypes recorded the lowest EP. Genotypes at ADL0023 locus were associated with AFE, EP at 40 weeks of age, CC (176 bp/176 bp) genotype followed by AB (202bp/188bp) genotype had earlier AFE, whereas, AC (202bp/176bp) genotype followed by BB (188bp/188bp) genotype demonstrated late AFE. ADL0210 locus had significant impact on AFE, egg weight at 28/40/64 weeks of age; BB (124bp/124bp) genotype followed by AA (132 bp/132 bp) genotype had earlier AFE than AB (132 bp/124 bp) genotype. Both AB and AA genotypes revealed significantly higher egg weight at 28/40/64 weeks of age than BB genotype. The BB (176 bp/176 bp) genotype followed by AB (192 bp/176 bp) genotype at MCW0014 locus revealed higher egg weight at 28 weeks of age in comparison to AA (192bp/192bp) genotype. Allele C (110 bp) at ADL0020 and A (132 bp) at ADL0210 either in homozygous or heterozygous condition were linked to the traits of egg weight and egg production performance, respectively. The results might impact on genomic selection aided poultry breeding programme.

Brain‐wide spatial analysis reveals cell‐type‐specific genetic modifiers of Alzheimer’s disease progression

AbstractBackgroundThere is significant variation in the age at onset and severity of cognitive decline among those with Alzheimer’s disease (AD). Despite strong genetic links to AD loci, the specific variants, target genes and cell types that drive AD‐related deterioration remain elusive. Recent advances in brain‐wide cell type and pathology quantification across our AD mouse genetic reference panel provide new opportunities to identify genetic factors that act in a cell‐type‐specific fashion to modify disease progression in response to causal AD mutations; linking, for the first time, genetics to regional cell composition to characterize susceptibility versus resilience to AD.MethodImmunohistochemistry was completed to evaluate neurodegeneration(NeuN), gliosis(Iba1&GFAP), and amyloid pathology(AB1‐42) in 250 mice from the AD‐BXD genetic reference panel. Using the QUINT workflow, hemibrain slices were systematically segmented and registered to the Allen Brain Atlas to gain a global perspective of percent cell/pathology coverage. The heritability of individual cell composition was calculated and quantitative trait loci(QTL) mapping was completed.ResultCompositional differences between the strains, particularly the BXD founder strains, became apparent when evaluating neurodegeneration and microglial proliferation. Despite comparable levels of amyloid, cortical and hippocampal NeuN and Iba1 coverage significantly varied among strains; however, this variation did not explain individual differences in short and long‐term memory capacity. Genetic mapping of individual cell composition traits identified a significant QTL associated with cortical neuron load (h = 0.6) on chromosome 17. Lrfn2 was identified as a gene of interest as it was differentially expressed between mice that had the BB vs BD genotype at the most significant variant location under the peak.ConclusionThis method of combining omics and imaging data to link changes in gene expression, cell composition, and behavior allows for the assessment of disease subtypes with the potential to aid the development of precision medicine solutions to AD. Specifically, changes in cell coverage can be associated with differences in gene expression among the AD‐BXD population to detect genes associated with regional cell composition. These candidates will be validated by creating cell‐type‐specific knock‐in or knock‐out models and measuring cognitive functioning to determine the effect of these genes on memory performance.

Investigating whether microsatellites could influence the relative expression level of TLR4 gene in bursa of Rhode Island Red chicken

TLR4 gene, vitally linked to resistance to infection with Salmonella enteric serovar Typhimurium in chickens, was chosen as a candidate gene for this investigation to assess the probable impact of microsatellite genotypes on relative expression of TLR4 gene. Our study documented variable expression level of TLR4 gene in tissue bursa of RIR chicken encoded with different microsatellite genotypes. The DD and CC genotypes of MCW0330 microsatellite demonstrated numerically higher mRNA expression than its AA, AC and BD genotypes. Therefore, The MCW0330 genotyping may predict TLR4 gene expression if confirmed by a thorough investigation taking a large number of samples and then would play an important role in host-pathogen genetics with respect to Salmonellosis in poultry.

Host species is linked to pathogen genotype for the amphibian chytrid fungus (Batrachochytrium dendrobatidis).

Host-pathogen specificity can arise from certain selective environments mediated by both the host and pathogen. Therefore, understanding the degree to which host species identity is correlated with pathogen genotype can help reveal historical host-pathogen dynamics. One animal disease of particular concern is chytridiomycosis, typically caused by the global panzootic lineage of the amphibian chytrid fungus (Batrachochytrium dendrobatidis, Bd), termed Bd-GPL. This pathogen lineage has caused devastating declines in amphibian communities around the world. However, the site of origin for the common ancestor of modern Bd-GPL and the fine-scale transmission dynamics of this lineage have remained a mystery. This is especially the case in North America where Bd-GPL is widespread, but disease outbreaks occur sporadically. Herein, we use Bd genetic data collected throughout the United States from amphibian skin swabs and cultured isolate samples to investigate Bd genetic patterns. We highlight two case studies in Pennsylvania and Nevada where Bd-GPL genotypes are strongly correlated with host species identity. Specifically, in some localities bullfrogs (Rana catesbeiana) are infected with Bd-GPL lineages that are distinct from those infecting other sympatric amphibian species. Overall, we reveal a previously unknown association of Bd genotype with host species and identify the eastern United States as a Bd diversity hotspot and potential site of origin for Bd-GPL.

Co-infecting pathogen lineages have additive effects on host bacterial communities.

Amphibian skin bacteria may confer protection against the fungus Batrachochytrium dendrobatidis (Bd), but responses of skin bacteria to different Bd lineages are poorly understood. The global panzootic lineage (Bd-GPL) has caused amphibian declines and extinctions globally. However, other lineages are enzootic (Bd-Asia-2/Brazil). Increased contact rates between Bd-GPL and enzootic lineages via globalization pose unknown consequences for host-microbiome-pathogen dynamics. We conducted a laboratory experiment and used 16S rRNA amplicon-sequencing to assess: (i) whether two lineages (Bd-Asia-2/Brazil and Bd-GPL) and their recombinant, in single and mixed infections, differentially affect amphibian skin bacteria; (ii) and the changes associated with the transition to laboratory conditions. We determined no clear differences in bacterial diversity among Bd treatments, despite differences in infection intensity. However, we observed an additive effect of mixed infections on bacterial alpha diversity and a potentially antagonistic interaction between Bd genotypes. Additionally, observed changes in community composition suggest a higher ability of Bd-GPL to alter skin bacteria. Lastly, we observed a drastic reduction in bacterial diversity and a change in community structure in laboratory conditions. We provide evidence for complex interactions between Bd genotypes and amphibian skin bacteria during coinfections, and expand on the implications of experimental conditions in ecological studies.

Early presence of Batrachochytrium dendrobatidis in Mexico with a contemporary dominance of the global panzootic lineage.

Chytridiomycosis, caused by the fungus Batrachochytrium dendrobatidis (Bd), is a devastating infectious disease of amphibians. Retrospective studies using museum vouchers and genetic samples supported the hypothesis that Bd colonized Mexico from North America and then continued to spread into Central and South America, where it led to dramatic losses in tropical amphibian biodiversity (the epizootic wave hypothesis). While these studies suggest that Bd has been in Mexico since the 1970s, information regarding the historical and contemporary occurrence of different pathogen genetic lineages across the country is limited. In the current study, we investigated the historical and contemporary patterns of Bd in Mexico. We combined the swabbing of historical museum vouchers and sampling of wild amphibians with a custom Bd genotyping assay to assess the presence, prevalence, and genetic diversity of Bd over time in Mexico. We found Bd-positive museum specimens from the late 1800s, far earlier than previous records and well before recent amphibian declines. With Bd genotypes from samples collected between 1975-2019, we observed a contemporary dominance of the global panzootic lineage in Mexico and report four genetic subpopulations and potential for admixture among these populations. The observed genetic variation did not have a clear geographic signature or provide clear support for the epizootic wave hypothesis. These results provide a framework for testing new questions regarding Bd invasions and their temporal relationship to observed amphibian declines in the Americas.

Evaluation of interaction between Brachypodium distachyon roots and Fusarium species

Fusarium Head Blight is the most important disease of cereals worldwide. Studies of interactions between different flower/grain pathogenic Fusarium species have been carried out, using the host and tissue from which the fungus was isolated. The aim of the present study was to assess the root responses of Brachypodium distachyon genotypes to Fusarium spp. to provide information about differences in host resistance and/or fungal aggressiveness. A total of 10 isolates of four Fusarium species were selected: F. graminearum, F. pseudograminearum, F. cerealis, and F. poae. A total of seven genotypes of B. distachyon were used: Afghanistan, Iran, Israel, Pakistan, South Africa, Uruguay and Bd genotype 21. Roots were inoculated and the necrosis root length was measured at 2, 4, 6, and 8 days post-inoculation. The results showed that F. graminearum and F. pseudograminearum were the species with the highest AUDPC values followed by F. cerealis that showed an intermediate value of AUDPC. F. poae was the least aggressive species. Regarding Brachypodium, the least affected genotype was Bd 21 and Pakistan, while the remaining genotypes showed differences in susceptibility. To our knowledge, this is the first report showing interaction between F. pseudograminearum, F. cerealis and F. poae with Brachypodium roots. Moreover, variability in susceptibility among Brachypodium genotypes and in Fusarium species aggressiveness was reported. We concluded that B. distachyon roots offer an efficient tissue system model to evaluate interaction with Fusarium spp.

Bullfrog farms release virulent zoospores of the frog-killing fungus into the natural environment

Bullfrog farming and trade practices are well-established, globally distributed, and economically valuable, but pose risks for biodiversity conservation. Besides their negative impacts on native amphibian populations as an invasive species, bullfrogs play a key role in spreading the frog-killing fungus Batrachochytrium dendrobatidis (Bd) in the natural environment. Bullfrogs are tolerant to Bd, meaning that they can carry high infection loads without developing chytridiomycosis. To test the potential of bullfrog farms as reservoirs for diverse and virulent chytrid genotypes, we quantified Bd presence, prevalence and infection loads across approximately 1,500 farmed bullfrogs and in the water that is released from farms into the environment. We also described Bd genotypic diversity within frog farms by isolating Bd from dozens of infected tadpoles. We observed individuals infected with Bd in all sampled farms, with high prevalence (reaching 100%) and high infection loads (average 71,029 zoospore genomic equivalents). Average outflow water volume from farms was high (60,000 L/day), with Bd zoospore concentration reaching approximately 50 million zoospores/L. Because virulent pathogen strains are often selected when growing in tolerant hosts, we experimentally tested whether Bd genotypes isolated from bullfrogs are more virulent in native anuran hosts compared to genotypes isolated from native host species. We genotyped 36 Bd isolates from two genetic lineages and found that Bd genotypes cultured from bullfrogs showed similar virulence in native toads when compared to genotypes isolated from native hosts. Our results indicate that bullfrog farms can harbor high Bd genotypic diversity and virulence and may be contributing to the spread of virulent genotypes in the natural environment. We highlight the urgent need to implement Bd monitoring and mitigation strategies in bullfrog farms to aid in the conservation of native amphibians.

Double trouble: co-infections of chytrid fungi will severely impact widely distributed newts

Invasive fungal pathogens Batrachochytrium dendrobatidis (Bd) and B. salamandrivorans (Bsal) are causing mortality events and population declines in amphibians around the world. B. salamandrivorans has not been found in the Americas but is predicted to emerge there given the presence of competent hosts, high volume import pathways, and lack of effective biosecurity measures. Eastern newts (Notophthalmus viridescens) are the most abundant and widespread salamanders in United States with known susceptibility to both fungi. However, little is known about how their current Bd infections will interact with novel Bsal infections. Here, we ran a series of experiments in which we exposed newts to each fungal pathogen, combinations of both fungi, and three Bd isolates to: (1) determine if natural exposure to Bd provides protection against Bsal, (2) quantify the effect of co-infections on newt survival, and (3) examine if resistance responses are general to multiple lineages. We found that hosts exposed under simultaneous co-infections experienced 78% mortality over a period of 18 weeks, which was driven by the persistence of Bsal because newts cleared Bd infection within a month. In a subsequent experiment, resistant newts also resolved infections of three Bd genotypes, suggesting that the defense mechanism is effective across all lineages. However, re-exposing these individuals with a tenfold higher dose (106Bd zoospores) increased their susceptibility to Bsal, and 93% of them sustained Bsal infections. Our findings will improve the estimates of decline risk for a species that could serve as a potential superspreader of Bsal in North America.

Diverse genotypes of the amphibian-killing fungus produce distinct phenotypes through plastic responses to temperature.

Phenotypes are the target of selection and affect the ability of organisms to persist in variable environments. Phenotypes can be influenced directly by genes and/or by phenotypic plasticity. The amphibian-killing fungus Batrachochytrium dendrobatidis (Bd) has a global distribution, unusually broad host range, and high genetic diversity. Phenotypic plasticity may be an important process that allows this pathogen to infect hundreds of species in diverse environments. We quantified phenotypic variation of nine Bd genotypes from two Bd lineages (Global Pandemic Lineage [GPL] and Brazil) and a hybrid (GPL-Brazil) grown at three temperatures (12, 18 and 24°C). We measured five functional traits including two morphological traits (zoospore and zoosporangium sizes) and three life history traits (carrying capacity, time to fastest growth and exponential growth rate) in a phylogenetic framework. Temperature caused highly plastic responses within each genotype, with all Bd genotypes showing phenotypic plasticity in at least three traits. Among genotypes, Bd generally showed the same direction of plastic response to temperature: larger zoosporangia, higher carrying capacity, longer time to fastest growth and slower exponential growth at lower temperatures. The exception was zoospore size, which was highly variable. Our findings indicate that Bd genotypes have evolved novel phenotypes through plastic responses to temperature over very short timescales. High phenotypic variability likely extends to other traits and may facilitate the large host range and rapid spread of Bd.

Genetic characterization of chytrids isolated from larval amphibians collected in central and east Texas

Abstract Chytridiomycosis, an emerging infectious disease caused by the fungal pathogen Batrachochytrium dendrobatidis (Bd), has caused amphibian population declines worldwide. Bd was first described in the 1990s and there are still geographic gaps in the genetic analysis of this globally distributed pathogen. Relatively few genetic studies have focused on regions where Bd exhibits low virulence, potentially creating a bias in our current knowledge of the pathogen's genetic diversity. Disease-associated declines have not been recorded in Texas (USA), yet Bd has been detected on amphibians in the state. These strains have not been isolated and characterized genetically; therefore, we isolated, cultured, and genotyped Bd from central Texas and compared isolates to a panel of previously genotyped strains distributed across the Western Hemisphere. We also isolated other chytrids from east Texas not known to infect amphibians. To identify larval amphibian hosts, we sequenced part of the COI gene. Among 37 Bd isolates from Texas, we detected 19 unique multi-locus genotypes, but found no genetic structure associated with host species, Texas localities, or across North America. Isolates from central Texas exhibit high diversity and genetically cluster with BdGPL isolates from the western U.S. that have caused amphibian population declines. This study genetically characterizes isolates of Bd from the south central U.S. and adds to the global knowledge of Bd genotypes.

Analysis of virulence diversity of 73 Helicobacterpylori strains isolated in Guizhou province, China.

The present study aimed to investigate the virulence diversity of Helicobacterpylori (H.pylori) in major ethnic groups residing in Guizhou province, China, and its association with clinical outcomes. Gastric mucosal biopsies were collected from the pylorus of patients with gastrointestinal disorders. H.pylori was identified by colonial morphology, Gram staining, a urease test and H.pylori‑specific 16S rRNA gene fragment PCR amplification. DNA was extracted from pure culture and used for virulence gene analysis. The cytotoxin associated gene A (cagA), vacuolating cytotoxin A (vacA) and induced by contact with epithelium gene A (iceA) genes were analyzed by polymerase chain reaction analysis. The cagA gene was further analyzed through sequencing of the C‑terminal region containing EPIYA motifs, and phylogenetic analysis of the cagA C‑terminal variable region was performed using MEGA 6.0software. In the present study, 73 H.pylori strains were isolated from clinical samples. cagA genotypes were detected in all strains, namely cagA‑AB, ‑ABC, ‑ABD and ‑BD genotypes were found in five (6.85%), three (4.11%), 63 (86.30%) and two (2.74%) isolates, respectively. Phylogenetic analysis showed that there was a clustering association between the cagA‑AB and cagA‑ABC genotypes, and between the cagA‑ABD and cagA‑BD genotypes. In terms of the frequency of the four EPIYA or EPIYA‑like motifs, the most predominant was EPIYA (92.92%), followed by EPIYT (3.77%), ESIYA (2.83%) and ESIYT (0.47%). The predominant vacA genotype was s1c/m2 (65.75%), and the predominant iceA genotype was iceA1 (79.45%). There were no associations between the H.pylori cagA, vacA or iceA genotypes and clinical outcomes. No significant difference was found in the distribution of these genotypes according to the age, ethnicity or location of residence of patients. In conclusion, H.pylori isolated from patients in Guizhou region, China, showed a unique genotype, which was mainly East Asia‑type cagA (ABD), vacA s1c/m2 genotype or iceA1‑postiive. These results provide important information on the distribution of H.pylori virulence genotypes in Guizhou province, China.

Hybrids of amphibian chytrid show high virulence in native hosts

Hybridization of parasites can generate new genotypes with high virulence. The fungal amphibian parasite Batrachochytrium dendrobatidis (Bd) hybridizes in Brazil’s Atlantic Forest, a biodiversity hotspot where amphibian declines have been linked to Bd, but the virulence of hybrid genotypes in native hosts has never been tested. We compared the virulence (measured as host mortality and infection burden) of hybrid Bd genotypes to the parental lineages, the putatively hypovirulent lineage Bd-Brazil and the hypervirulent Global Pandemic Lineage (Bd-GPL), in a panel of native Brazilian hosts. In Brachycephalus ephippium, the hybrid exceeded the virulence (host mortality) of both parents, suggesting that novelty arising from hybridization of Bd is a conservation concern. In Ischnocnema parva, host mortality in the hybrid treatment was intermediate between the parent treatments, suggesting that this species is more vulnerable to the aggressive phenotypes associated with Bd-GPL. Dendropsophus minutus showed low overall mortality, but infection burdens were higher in frogs treated with hybrid and Bd-GPL genotypes than with Bd-Brazil genotypes. Our experiment suggests that Bd hybrids have the potential to increase disease risk in native hosts. Continued surveillance is needed to track potential spread of hybrid genotypes and detect future genomic shifts in this dynamic disease system.

Opening the file drawer: Unexpected insights from a chytrid infection experiment

Infection experiments are critical for understanding wildlife disease dynamics. Although infection experiments are typically designed to reduce complexity, disease outcomes still result from complex interactions between host, pathogen, and environmental factors. Cryptic variation across factors can lead to decreased repeatability of infection experiments within and between research groups and hinder research progress. Furthermore, studies with unexpected results are often relegated to the “file drawer” and potential insights gained from these experimental outcomes are lost. Here, we report unexpected results from an infection experiment studying the response of two differentially-susceptible but related frogs (American Bullfrog Rana catesbeiana and the Mountain yellow-legged frog Rana muscosa) to the amphibian-killing chytrid fungus (Batrachochytrium dendrobatidis, Bd). Despite well-documented differences in susceptibility between species, we found no evidence for antibody-mediated immune response and no Bd-related mortality in either species. Additionally, during the study, the sham-inoculated R. catesbeiana control group became unexpectedly Bd-positive. We used a custom genotyping assay to demonstrate that the aberrantly-infected R. catesbeiana carried a Bd genotype distinct from the inoculation genotype. Thus R. catesbeiana individuals were acquired with low-intensity infections that could not be detected with qPCR. In the Bd-inoculated R. catesbeiana treatment group, the inoculated genotype appeared to out-compete the cryptic infection. Thus, our results provide insight into Bd coinfection dynamics, a phenomenon that is increasingly relevant as different pathogen strains are moved around the globe. Our experiment highlights how unexpected experimental outcomes can serve as both cautionary tales and opportunities to explore unanswered research questions. We use our results as a case study to highlight common sources of anomalous results for infection experiments. We argue that understanding these factors will aid researchers in the design, execution, and interpretation of experiments to understand wildlife disease processes.

Haemoglobin polymorphism in wild and cultured African catfish (<i>Clarias gariepinus</i> Burchell, 1822)

Haemoglobin polymorphism, haemoglobin concentration, blood group and genotypes of wild and cultured Clarias gariepinus were investigated. Blood samples of Clarias gariepinus collected from Lake Alau (wild) and Dalori fish farm (cultured) were subjected to cellulose acetate electrophoresis to reveal the activities of hemoglobin (Hb). The result shows that both wild and cultured C. gariepinus had AA, BB and CC genotypes in the males and females. However, BD genotype was observed only in the female wild C. gariepinus . The percentage AA and BB genotypes of wild male C. gariepinus was 6.6% each. Wild females had AA, BB, CC and BD genotype with frequencies of 26.6, 33.3, 20 and 6.6% respectively. Cultured male C. gariepinus had AA, BB and CC with frequencies of 13.3, 26.6 and 6.6%, respectively, while the female C. gariepinus had AA, BB and CC with frequencies of 20, 13.3 and 20% respectively. Wild C. gariepinus had the highest (10.36 g/dl) haemoglobin concentration value while the cultured strain had 8.86 g/dl. The blood groups of wild male C. gariepinus were O - (10% of the population) and AB + (10% of the population). The wild females had O - , O + , A + , B + and AB + with 40, 10, 10, 10 and 10% of the population respectively, Cultured male had O + , A + and AB + (10, 20 and 20% of the fish observed) respectively. The blood group observed in the cultured female C. gariepinus were O - (30%), A + (10%) and B + (10%). The BD genotype observed in a wild strain of C. gariepinus indicates incomplete (partial) dominance and rare allele. This could be an indication of natural hybridization. Keywords : Haemoglobin concentration, polymorphism, genotype, blood group, wild and cultured, Clarias

Estimating Herd Immunity to Amphibian Chytridiomycosis in Madagascar Based on the Defensive Function of Amphibian Skin Bacteria.

For decades, Amphibians have been globally threatened by the still expanding infectious disease, chytridiomycosis. Madagascar is an amphibian biodiversity hotspot where Batrachochytrium dendrobatidis (Bd) has only recently been detected. While no Bd-associated population declines have been reported, the risk of declines is high when invasive virulent lineages become involved. Cutaneous bacteria contribute to host innate immunity by providing defense against pathogens for numerous animals, including amphibians. Little is known, however, about the cutaneous bacterial residents of Malagasy amphibians and the functional capacity they have against Bd. We cultured 3179 skin bacterial isolates from over 90 frog species across Madagascar, identified them via Sanger sequencing of approximately 700 bp of the 16S rRNA gene, and characterized their functional capacity against Bd. A subset of isolates was also tested against multiple Bd genotypes. In addition, we applied the concept of herd immunity to estimate Bd-associated risk for amphibian communities across Madagascar based on bacterial antifungal activity. We found that multiple bacterial isolates (39% of all isolates) cultured from the skin of Malagasy frogs were able to inhibit Bd. Mean inhibition was weakly correlated with bacterial phylogeny, and certain taxonomic groups appear to have a high proportion of inhibitory isolates, such as the Enterobacteriaceae, Pseudomonadaceae, and Xanthamonadaceae (84, 80, and 75% respectively). Functional capacity of bacteria against Bd varied among Bd genotypes; however, there were some bacteria that showed broad spectrum inhibition against all tested Bd genotypes, suggesting that these bacteria would be good candidates for probiotic therapies. We estimated Bd-associated risk for sampled amphibian communities based on the concept of herd immunity. Multiple amphibian communities, including those in the amphibian diversity hotspots, Andasibe and Ranomafana, were estimated to be below the 80% herd immunity threshold, suggesting they may be at higher risk to chytridiomycosis if a lethal Bd genotype emerges in Madagascar. While this predictive approach rests on multiple assumptions, and incorporates only one component of hosts' defense against Bd, their culturable cutaneous bacterial defense, it can serve as a foundation for continued research on Bd-associated risk for the endemic frogs of Madagascar.

Dr Jekyll and Mrs Hyde: Risky hybrid sex by amphibian‐parasitizing chytrids in the Brazilian Atlantic Forests

In their article in this issue of Molecular Ecology, Jenkinson etal. () and colleagues address a worrying question-how could arguably the most dangerous pathogen known to science, Batrachochytrium dendrobatidis (Bd), become even more virulent? The answer: start having sex. Jenkinson etal. present a case for how the introduction into Brazil of the globally invasive lineage of Bd, BdGPL, has disrupted the relationship between native amphibians and an endemic Bd lineage, BdBrazil. BdBrazil is hypothesized to be native to the Atlantic Forest and so have a long co-evolutionary history with biodiverse Atlantic Forest amphibian community. The authors suggest that this has resulted in a zone of hybrid Bd genotypes which are potentially more likely to cause fatal chytridiomycosis than either parent lineage. The endemic-nonendemic Bd hybrid genotypes described in this study, and the evidence for pathogen translocation via the global amphibian trade presented, highlights the danger of anthropogenic pathogen dispersal. This research emphasizes that biosecurity regulations may have to refocus on lineages within species if we are to mitigate against the danger of new, possibly hypervirulent genotypes of pathogens emerging as phylogeographic barriers are breached.

Widespread presence of the pathogenic fungus Batrachochytrium dendrobatidis in wild amphibian communities in Madagascar.

Amphibian chytridiomycosis, an emerging infectious disease caused by the fungus Batrachochytrium dendrobatidis (Bd), has been a significant driver of amphibian declines. While globally widespread, Bd had not yet been reported from within Madagascar. We document surveys conducted across the country between 2005 and 2014, showing Bd's first record in 2010. Subsequently, Bd was detected in multiple areas, with prevalence reaching up to 100%. Detection of Bd appears to be associated with mid to high elevation sites and to have a seasonal pattern, with greater detectability during the dry season. Lineage-based PCR was performed on a subset of samples. While some did not amplify with any lineage probe, when a positive signal was observed, samples were most similar to the Global Panzootic Lineage (BdGPL). These results may suggest that Bd arrived recently, but do not exclude the existence of a previously undetected endemic Bd genotype. Representatives of all native anuran families have tested Bd-positive, and exposure trials confirm infection by Bd is possible. Bd's presence could pose significant threats to Madagascar's unique “megadiverse” amphibians.

Allelic and genotypic frequencies of platelet glycoprotein polymorphisms in a Portuguese population

Introduction and objectivesWe studied genotypic and allelic frequencies of polymorphisms that can affect platelet function, namely the Kozak, VNTR and HPA-2 polymorphisms of glycoprotein Ibα, the PlA polymorphism of glycoprotein IIIa and the C807T polymorphism of glycoprotein Ia, in a Portuguese population composed of 227 donors. MethodsPCR-RFLP was used to assess the Kozak, HPA-2, PlA and C807T polymorphisms. The VNTR polymorphism was discriminated by different weight bands on electrophoresis. ResultsAll genotypic frequencies were in Hardy-Weinberg equilibrium and do not differ from other Caucasian populations. Genotypic frequencies were 68.3%, 26.9% and 4.8% for PlA1/A1, PlA1/A2 and PlA2/A2 genotypes of the PlA polymorphism, 79.3%, 20.3% and 0.4% for TT, TC and CC genotypes of the Kozak polymorphism, 81.1%, 18.9% and 0.0% for aa, ab and bb genotypes of the HPA-2 polymorphism, 15.4%, 0.9%, 70.5%, 11.5%, 1.3% and 0.4% for BC, BD, CC, CD, DD and CE genotypes of the VNTR polymorphism, and 39.7%, 50.2% and 10.1% for CC, CT and TT genotypes of the C807T polymorphism. ConclusionsThe Portuguese population has now been characterized in terms of major platelet glycoprotein polymorphisms, which will be an important tool for further studies to assess the role of platelet glycoproteins in individual predisposition to prothrombotic conditions and response to antithrombotic therapy.

Allelic and genotypic frequencies of platelet glycoprotein polymorphisms in a Portuguese population

Introduction and objectivesWe studied genotypic and allelic frequencies of polymorphisms that can affect platelet function, namely the Kozak, VNTR and HPA-2 polymorphisms of glycoprotein Ibα, the PlA polymorphism of glycoprotein IIIa and the C807T polymorphism of glycoprotein Ia, in a Portuguese population composed of 227 donors. MethodsPCR-RFLP was used to assess the Kozak, HPA-2, PlA and C807T polymorphisms. The VNTR polymorphism was discriminated by different weight bands on electrophoresis. ResultsAll genotypic frequencies were in Hardy-Weinberg equilibrium and do not differ from other Caucasian populations. Genotypic frequencies were 68.3%, 26.9% and 4.8% for PlA1/A1, PlA1/A2 and PlA2/A2 genotypes of the PlA polymorphism, 79.3%, 20.3% and 0.4% for TT, TC and CC genotypes of the Kozak polymorphism, 81.1%, 18.9% and 0.0% for aa, ab and bb genotypes of the HPA-2 polymorphism, 15.4%, 0.9%, 70.5%, 11.5%, 1.3% and 0.4% for BC, BD, CC, CD, DD and CE genotypes of the VNTR polymorphism, and 39.7%, 50.2% and 10.1% for CC, CT and TT genotypes of the C807T polymorphism. ConclusionsThe Portuguese population has now been characterized in terms of major platelet glycoprotein polymorphisms, which will be an important tool for further studies to assess the role of platelet glycoproteins in individual predisposition to prothrombotic conditions and response to antithrombotic therapy.