The genetics of hybrid male sterility between the allopatric species pair Drosophila persimilis and D. pseudoobscura bogotana: dominant sterility alleles in collinear autosomal regions

F(1) hybrid male sterility is thought to result from interactions between loci on the X chromosome and dominant-acting loci on the autosomes. While X-linked loci that contribute to hybrid male sterility have been precisely localized in many animal taxa, their dominant autosomal interactors have been more difficult to localize precisely and/or have been shown to be of relatively smaller effect. Here, we identified and mapped at least four dominant autosomal factors contributing to hybrid male sterility in the allopatric species pair Drosophila persimilis and D. pseudoobscura bogotana. Using these results, we tested predictions of reduced recombination models of speciation. Consistent with these models, three of the four QTL associated with hybrid male sterility occur in collinear (uninverted) regions of these genomes. Furthermore, these QTL do not contribute significantly to hybrid male sterility in crosses between the sympatric species D. persimilis and D. pseudoobscura pseudoobscura. The autosomal loci identified in this study provide the basis for introgression mapping and, ultimately, for molecular cloning of interacting genes that contribute to F(1) hybrid sterility.     

Population genetics reveals bidirectional fish movement across the Continental Divide via an interbasin water transfer

Interbasin water transfers are becoming an increasingly common tool to satisfy municipal and agricultural water demand, but their impacts on movement and gene flow of aquatic organisms are poorly understood. The Grand Ditch is an interbasin water transfer that diverts water from tributaries of the upper Colorado River on the west side of the Continental Divide to the upper Cache la Poudre River on the east side of the Continental Divide. We used single nucleotide polymorphisms to characterize population genetic structure in cutthroat trout (Oncorhynchus clarkii) and determine if fish utilize the Grand Ditch as a movement corridor. Samples were collected from two sites on the west side and three sites on the east side of the Continental Divide. We identified two or three genetic clusters, and relative migration rates and spatial distributions of admixed individuals indicated that the Grand Ditch facilitated bidirectional fish movement across the Continental Divide, a major biogeographic barrier. Previous studies have demonstrated ecological impacts of interbasin water transfers, but our study is one of the first to use genetics to understand how interbasin water transfers affect connectivity between previously isolated watersheds. We also discuss implications on native trout management and balancing water demand and biodiversity conservation.

     

Exploring the effect of 195 years-old locks on species movement: landscape genetics of painted turtles in the Rideau Canal,Canada

Aquatic systems have been extensively altered by human structures (e.g., construction of dams/canals) and these have major impacts on the connectivity of wildlife populations through the loss and isolation of suitable habitats. Habitat loss and isolation affect gene flow and influence the persistence of populations in time and space by restricting movements. Isolation can result in higher inbreeding, lower genetic diversity, and greater genetic structure, which may render populations more vulnerable to environmental changes, and thus to extinction. Given the ubiquity and the persistence of dams and canals in space and time, it is crucial to understand their effects on the population genetics of aquatic species. Here, we documented the genetic diversity and structure of painted turtle (Chrysemys picta) populations in the Rideau Canal, Ontario, Canada. More specifically, we used 13 microsatellites to evaluate the influence of locks on genetic variation in 822 painted turtles from 22 sites evenly distributed along the 202-km canal. Overall, we found low, but significant, genetic differentiation suggesting that some dispersal is occurring throughout the canal. In addition, we showed that locks contribute to the genetic differentiation observed in the system. Clustering analysis revealed two distinct genetic groups whose boundary is associated with a series of six locks. Our results illustrate how artificial waterways, such as canal systems, can influence population genetic structure. We highlight the importance of adopting management plans that can mitigate the impacts of human infrastructure and preserve gene flow across the landscape to maintain viable populations.

     

Human Semaphorin 3 Variants Link Melanocortin Circuit Development and Energy Balance

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Insect cell expression and purification of recombinant SARS‐COV‐2 spike proteins that demonstrate ACE2 binding

The COVID‐19 pandemic caused by SARS‐CoV‐2 infection has led to socio‐economic shutdowns and the loss of over 5 million lives worldwide. There is a need for the identification of therapeutic targets to treat COVID‐19. SARS‐CoV‐2 spike is a target of interest for the development of therapeutic targets. We developed a robust SARS‐CoV‐2 S spike expression and purification protocol from insect cells and studied four recombinant SARS‐CoV‐2 spike protein constructs based on the original SARS‐CoV‐2 sequence using a baculovirus expression system: a spike protein receptor‐binding domain that includes the SD1 domain (RBD) coupled to a fluorescent tag (S‐RBD‐eGFP), spike ectodomain coupled to a fluorescent tag (S‐Ecto‐eGFP), spike ectodomain with six proline mutations and a foldon domain (S‐Ecto‐HexaPro(+F)), and spike ectodomain with six proline mutations without the foldon domain (S‐Ecto‐HexaPro(‐F)). We tested the yield of purified protein expressed from the insect cell lines Spodoptera frugiperda (Sf9) and Trichoplusia ni (Tni) and compared it to previous research using mammalian cell lines to determine changes in protein yield. We demonstrated quick and inexpensive production of functional glycosylated spike protein of high purity capable of recognizing and binding to the angiotensin converting enzyme 2 (ACE2) receptor. To further confirm functionality, we demonstrate binding of eGFP fused construct of the spike ectodomain (S‐Ecto‐eGFP) to surface ACE2 receptors on lung epithelial cells by flow cytometry analysis and show that it can be decreased by means of receptor manipulation (blockade or downregulation).     

Polymorphism of dopamine receptor D4 exon I corresponding region in chicken

In stockbreeding, there are indications that behavioral traits of livestock have an effect on breeding and production. If the variation in individual behavior is related to that in neurotransmitter-related genes such as in humans, it would be possible to breed pedigrees composed of individuals having behavioral traits that are useful to production and breeding using selection based on genotypes. In this study, we investigated the exon I region of dopamine receptor D4 (DRD4), in which variation is related to psychiatric disorder in humans, in major poultry species namely Japanese quail (Coturnix japonica), chicken (Gallus gallus), ring-necked pheasant (Phasianus colchicus) and helmeted guinea fowl (Numida meleagris). Furthermore, we investigated Japanese cormorant (Phalacrocorax capillatus) and Japanese jungle crow (Corvus macrorhynchos) as an out-group. In these species of birds, the repeat of proline was identified in the region corresponding to the human polymorphic region. The repeat number was 9 in Japanese quail, ring-necked pheasant and Japanese cormorant; 12 in helmeted guinea fowl; and 3 in Japanese jungle crow. However, no polymorphism was found in these species. In contrast, polymorphism was observed in chicken and two alleles with 8 and 9 repeats were identified. Although 9 repeats (allele 9) were predominant in most chicken breeds, Black Minorca had only 8 repeats (allele 8). Intra-breed polymorphism was found in 6 out of 12 breeds, and two alleles (alleles 8 and 9) were detected in these breeds. This polymorphism, which is the first to be reported on a neurotransmitter-related gene in birds, would contribute significant information for elucidation of differences in behavioral traits in chicken breeds.