CbpA is one of the six E. coli DnaJ/Hsp40 homologues of DnaK co-chaperones and the only one that is additionally regulated by a small protein CbpM, conserved in γ-proteobacteria. CbpM inhibits the co-chaperone and DNA binding activities of CbpA. This regulatory function of CbpM is accomplished through reversible interaction with the N-terminal J-domain of CbpA, which is essential for the interaction with DnaK. CbpM is highly specific for CbpA and does not bind DnaJ despite the high degree of structural and functional similarity between the J-domains of CbpA and DnaJ. Here we report the crystal structure of the complex of CbpM with the J-domain of CbpA. CbpM forms dimers and the J-domain of CbpA interacts with both CbpM subunits. The CbpM-binding surface of CbpA is highly overlapping with the CbpA interface for DnaK, providing a competitive model for regulation through forming mutually exclusive complexes. The structure also provides the explanation for the strict specificity of CbpM for CbpA, which we confirmed by making mutants of DnaJ that became regulated by CbpM. Interestingly, the structure of CbpM reveals a striking similarity to members of the MerR family of transcriptional regulators, suggesting an evolutionary connection between the functionally distinct bacterial co-chaperone regulator CbpM and the transcription regulator HspR.
Two inbred mouse strains, CBA/J and CBA/CaJ, have been used nearly interchangeably as ‘good hearing’ standards for research in hearing and deafness. We recently reported, however, that these two strains diverge after 1 year of age, such that CBA/CaJ mice show more rapid elevation of compound action potential (CAP) thresholds at high frequencies (Ohlemiller, Brain Res. 1277: 70–83, 2009). One contributor is progressive decline in endocochlear potential (EP) that appears only in CBA/CaJ. Here, we explore the cellular bases of threshold and EP disparities in old CBA/J and CBA/CaJ mice. Among the major findings, both strains exhibit a characteristic age (∼18 months in CBA/J and 24 months in CBA/CaJ) when females overtake males in sensitivity decline. Strain differences in progression of hearing loss are not due to greater hair cell loss in CBA/CaJ, but instead appear to reflect greater neuronal loss, plus more pronounced changes in the lateral wall, leading to EP decline. While both male and female CBA/CaJ show these pathologies, they are more pronounced in females. A novel feature that differed sharply by strain was moderate loss of outer sulcus cells (or ‘root’ cells) in spiral ligament of the upper basal turn in old CBA/CaJ mice, giving rise to deep indentations and void spaces in the ligament. We conclude that CBA/CaJ mice differ both quantitatively and qualitatively from CBA/J in age-related cochlear pathology, and model different types of presbycusis.
presbycusis; stria vascularis; spiral ligament; endocochlear potential; hair cells; outer sulcus cells; marginal cells; gender effects; spiral ganglion
Crystallization of a family 84 glycoside hydrolase, a putative virulence factor, secreted by C. perfringens is reported.
Clostridium perfringens is a ubiquitous environmental organism that is capable of causing a variety of diseases in mammals, including gas gangrene and necrotic enteritis in humans. The activity of a secreted hyaluronidase, attributed to the NagH protein, contributes to the pathogenicity of this organism. The family 84 catalytic module of one of the three homologues of NagH found in C. perfringens (ATCC 13124) has been cloned. The 69 kDa catalytic module of NagJ, here called GH84C, was overproduced in Escherichia coli and purified by immobilized metal-affinity chromatography (IMAC). Crystals belonging to space group I222 or I212121 with unit-cell parameters a = 130.39, b = 150.05, c = 155.43 Å were obtained that diffracted to 2.1 Å. Selenomethionyl crystals have also been produced, leading to the possibility of solving the phase problem by MAD using synchrotron radiation.
Clostridium perfringens; hyaluronidases; family 84 glycoside hydrolases; carbohydrates; hexosaminidases
Accurate readability assessment of health related materials is a critical first step in producing easily understandable consumer health information resources and personal health records. Existing general readability formulas may not always be appropriate for the medical/consumer health domain. We developed a new health-specific readability pilot measure, based on the differences in semantic and syntactic features as well as text unit length. The tool was tested with 4 types of materials: consumer health texts, electronic health records, health news articles, and scientific biomedical journals. The results were compared with those produced by three commonly used general readability formulas. While the general formulas underestimated the difficulty of health records by placing them at the same grade levels as consumer health texts, our method rated health records as the most difficult type of documents. Our ratings, however, were highly correlated with general formulas ratings of consumer health, news, and journal articles (r=0.81~0.85, p<.0001).
readability; consumer health informatics
Many biomolecules have machine-like functions, and accordingly are discussed in terms of mechanical properties like force and motion. However, the concept of stress, a mechanical property that is of fundamental importance in the study of macroscopic mechanics, is not commonly applied in the biomolecular context. We anticipate that microscopical stress analyses of biomolecules and nanomaterials will provide useful mechanistic insights and help guide molecular design. To enable such applications, we have developed Calculator of Atomistic Mechanical Stress (CAMS), an open-source software package for computing atomic resolution stresses from molecular dynamics (MD) simulations. The software also enables decomposition of stress into contributions from bonded, nonbonded and Generalized Born potential terms. CAMS reads GROMACS topology and trajectory files, which are easily generated from AMBER files as well; and time-varying stresses may be animated and visualized in the VMD viewer. Here, we review relevant theory and present illustrative applications.
Extensive morphogenetic remodelling takes place during metamorphosis from a larval to an adult insect body plan. These changes are particularly intricate in the generation of the dipteran wing hinge, a complex structure that is derived from an apparently simple region of the wing imaginal disc. Using the characterisation of original outstretched alleles of the unpaired locus as a starting point, we demonstrate the role of JAK/STAT pathway signalling in the process of wing hinge development. We show that differences in JAK/STAT signalling within the proximal most of three lateral folds present in the wing imaginal disc is required for fold morphology and the subsequent differentiation of the first and second auxiliary sclerites as well as the posterior notal wing process. Changes in these domains are consistent with the established fate map of the wing disc. We show that outstretched wing posture phenotypes arise from the loss of a region of Unpaired expression in the proximal wing fold and demonstrate that this results in a decrease in JAK/STAT pathway activity. Finally we show that reduction of JAK/STAT pathway activity within the proximal wing fold is sufficient to phenocopy the outstretched phenotype. Taken together, we suggest that localised Unpaired expression and hence JAK/STAT pathway activity, is required for the morphogenesis of the adult wing hinge, providing new insights into the link between signal transduction pathways, patterning and development.
Transcriptional regulation critically depends on proper interactions between transcription factors (TF) and their cognate DNA binding sites. The widely used model of TF-DNA binding – the Positional Weight Matrix (PWM) – presumes independence between positions within the binding site. However, there is evidence to show that the independence assumption may not always hold, and the extent of interposition dependence is not completely known. We hypothesize that the interposition dependence should partly be manifested as correlated evolution at the positions. We report a Maximum-Likelihood (ML) approach to infer correlated evolution at any two positions within a PWM, based on a multiple alignment of 5 mammalian genomes. Application to a genome-wide set of putative cis elements in human promoters reveals a prevalence of correlated evolution within cis elements. We found that the interdependence between two positions decreases with increasing distance between the positions. The interdependent positions tend to be evolutionarily more constrained and moreover, the dependence patterns are relatively similar across structurally related transcription factors. Although some of the detected mutational dependencies may be due to context-dependent genomic hyper-mutation, notably CG to TG, the majority is likely due to context-dependent preferences for specific nucleotide combinations within the cis elements. Patterns of evolution at individual nucleotide positions within mammalian TF binding sites are often significantly correlated, suggesting interposition dependence. The proposed methodology is also applicable to other classes of non-coding functional elements. A detailed investigation of mutational dependencies within specific motifs could reveal preferred nucleotide combinations that may help refine the DNA binding models.
Metabolic and psychiatric disturbances occur early on in the clinical manifestation of Huntington’s disease (HD), a neurodegenerative disorder caused by an expanded CAG repeat in the huntingtin (HTT) gene. Hypothalamus has emerged as an important site of pathology and alterations in this area and its neuroendocrine circuits may play a role in causing early non-motor symptoms and signs in HD. Leptin is a hormone that controls energy homeostasis by signaling through leptin receptors in the hypothalamus. Disturbed leptin action is implicated in both obesity and depression and altered circulating levels of leptin have been reported in both clinical HD and rodent models of the disease. Pathological leptin signaling may therefore be involved in causing the metabolic and psychiatric disturbances of HD. Here we tested the hypothesis that expression of mutant HTT in leptin receptor carrying neurons plays a role in the development of the non-motor phenotype in the BACHD mouse model. Our results show that inactivation of mutant HTT in leptin receptor-expressing neurons in the BACHD mouse using cross-breeding based on a cre-loxP system did not have an effect on the metabolic phenotype or anxiety-like behavior. The data suggest that mutant HTT disrupts critical hypothalamic pathways by other mechanisms than interfering with intracellular leptin signaling.
Endosomal sorting mechanisms mediated by AP-3 and BLOC-1 are perturbed in Hermansky-Pudlak Syndrome, a human genetic condition characterized by albinism and prolonged bleeding (OMIM #203300). Additionally, mouse models defective in either one of these complexes possess defective synaptic vesicle biogenesis (Newell-Litwa et al., 2009). These synaptic vesicle phenotypes were presumed uniform throughout the brain. However, here we report that AP-3 and BLOC-1 differentially regulate the composition of pre-synaptic terminals in the striatum and dentate gyrus of the hippocampus. Quantitative immunoelectron microscopy demonstrated that the majority of AP-3 immunoreactivity in both wild type striatum and hippocampus localizes to pre-synaptic axonal compartments, where it regulates synaptic vesicle size. In the striatum, loss of AP-3 (Ap3dmh/mh) resulted in decreased synaptic vesicle size. In contrast, loss of AP-3 in the dentate gyrus increased synaptic vesicle size, thus suggesting anatomically specific AP-3-regulatory mechanisms. Loss-of-function alleles of BLOC-1, Pldnpa/pa and Mutedmu/mu, revealed that this complex acts as a brain-region specific regulator of AP-3. In fact, BLOC-1 deficiencies selectively reduced AP-3 and AP-3 cargo immunoreactivity in pre-synaptic compartments within the dentate gyrus both at the light and/or electron microscopy level. However, the striatum did not exhibit these BLOC-1-null phenotypes. Our results demonstrate that distinct brain regions differentially regulate AP-3-dependent synaptic vesicle biogenesis. We propose that anatomically restricted mechanisms within the brain diversify the biogenesis and composition of synaptic vesicles.
Synapse; Synaptic; dentate gyrus; striatum; presynaptic regulation; Membrane
The SILVER locus has been mapped in the domestic cat, identifying a unique genomic location distinct from that of any known reported gene associated with silver or hypopigmentation in mammals. A demonstrated lack of linkage to SILV, the strong candidate gene for silver, led to the initiation of a genome scan utilizing 2 pedigrees segregating for silver coat color. Linkage mapping defined a genomic region for SILVER as a 3.3-Mb region, (95.87–99.21 Mb) on chromosome D2, (peak logarithm of the odds = 10.5, θ = 0), which displays conserved synteny to a genomic interval between 118.58 and 121.85 Mb on chromosome 10 in the human genome. In the domestic cat, mutations at the SILVER locus suppress the development of pigment in the hair, but in contrast to other mammalian silver variants, there is an apparently greater influence on the production of pheomelanin than eumelanin pigment. The mapping of a novel locus for SILVER offers much promise in identifying a gene that may help elucidate aspects of pheomelanogenesis, a pathway that has been very elusive, and illustrates the promise of the cat genome project in increasing our understanding of basic biological processes of general relevance for mammals.
coat color; domestic cat; genetic linkage mapping; pheomelanogenic; SILVER
Variation in endocrine signaling is proposed to underlie the evolution and regulation of social life histories, but the genetic architecture of endocrine signaling is still poorly understood. An excellent example of a hormonally influenced set of social traits is found in the honey bee (Apis mellifera): a dynamic and mutually suppressive relationship between juvenile hormone (JH) and the yolk precursor protein vitellogenin (Vg) regulates behavioral maturation and foraging of workers. Several other traits cosegregate with these behavioral phenotypes, comprising the pollen hoarding syndrome (PHS) one of the best-described animal behavioral syndromes. Genotype differences in responsiveness of JH to Vg are a potential mechanistic basis for the PHS. Here, we reduced Vg expression via RNA interference in progeny from a backcross between 2 selected lines of honey bees that differ in JH responsiveness to Vg reduction and measured JH response and ovary size, which represents another key aspect of the PHS. Genetic mapping based on restriction site-associated DNA tag sequencing identified suggestive quantitative trait loci (QTL) for ovary size and JH responsiveness. We confirmed genetic effects on both traits near many QTL that had been identified previously for their effect on various PHS traits. Thus, our results support a role for endocrine control of complex traits at a genetic level. Furthermore, this first example of a genetic map of a hormonal response to gene knockdown in a social insect helps to refine the genetic understanding of complex behaviors and the physiology that may underlie behavioral control in general.
Apis mellifera; complex trait genetics; genetic architecture juvenile hormone; social evolution; vitellogenin
Over 95% of all metazoan (animal) species comprise the “invertebrates,” but very few genomes from these organisms have been sequenced. We have, therefore, formed a “Global Invertebrate Genomics Alliance” (GIGA). Our intent is to build a collaborative network of diverse scientists to tackle major challenges (e.g., species selection, sample collection and storage, sequence assembly, annotation, analytical tools) associated with genome/transcriptome sequencing across a large taxonomic spectrum. We aim to promote standards that will facilitate comparative approaches to invertebrate genomics and collaborations across the international scientific community. Candidate study taxa include species from Porifera, Ctenophora, Cnidaria, Placozoa, Mollusca, Arthropoda, Echinodermata, Annelida, Bryozoa, and Platyhelminthes, among others. GIGA will target 7000 noninsect/nonnematode species, with an emphasis on marine taxa because of the unrivaled phyletic diversity in the oceans. Priorities for selecting invertebrates for sequencing will include, but are not restricted to, their phylogenetic placement; relevance to organismal, ecological, and conservation research; and their importance to fisheries and human health. We highlight benefits of sequencing both whole genomes (DNA) and transcriptomes and also suggest policies for genomic-level data access and sharing based on transparency and inclusiveness. The GIGA Web site (http://giga.nova.edu) has been launched to facilitate this collaborative venture.
biodiversity; comparative genomics; consortium; evolution; GIGA; invertebrates; metazoa
Revealing the genetic basis of traits that cause reproductive isolation,
particularly premating or sexual isolation, usually involves the same challenges
as most attempts at genotype–phenotype mapping and so requires knowledge
of how these traits are expressed in different individuals, populations, and
environments, particularly under natural conditions. Genetic dissection of
speciation phenotypes thus requires understanding of the internal and external
contexts in which underlying genetic elements are expressed. Gene expression is
a product of complex interacting factors internal and external to the organism
including developmental programs, the genetic background including
nuclear–cytotype interactions, epistatic relationships, interactions
among individuals or social effects, stochasticity, and prevailing variation in
ecological conditions. Understanding of genomic divergence associated with
reproductive isolation will be facilitated by functional expression analysis of
annotated genomes in organisms with well-studied evolutionary histories,
phylogenetic affinities, and known patterns of ecological variation throughout
their life cycles. I review progress and prospects for understanding the
pervasive role of host plant use on genetic and phenotypic expression of
reproductive isolating mechanisms in cactophilic Drosophila
mojavensis and suggest how this system can be used as a model for
revealing the genetic basis for species formation in organisms where speciation
phenotypes are under the joint influences of genetic and environmental
cactus; courtship song; cuticular hydrocarbon; Drosophila; gene ontology; microarray; Sonoran Desert; speciation; transcriptome
Globally distributed, the bottlenose dolphin (Tursiops truncatus) is found in a range of offshore and coastal habitats. Using 15 microsatellite loci and mtDNA control region sequences, we investigated patterns of genetic differentiation among putative populations along the eastern US shoreline (the Indian River Lagoon, Florida, and Charleston Harbor, South Carolina) (microsatellite analyses: n = 125, mtDNA analyses: n = 132). We further utilized the mtDNA to compare these populations with those from the Northwest Atlantic, Gulf of Mexico, and Caribbean. Results showed strong differentiation among inshore, alongshore, and offshore habitats (ФST = 0.744). In addition, Bayesian clustering analyses revealed the presence of 2 genetic clusters (populations) within the 250 km Indian River Lagoon. Habitat heterogeneity is likely an important force diversifying bottlenose dolphin populations through its influence on social behavior and foraging strategy. We propose that the spatial pattern of genetic variation within the lagoon reflects both its steep longitudinal transition of climate and also its historical discontinuity and recent connection as part of Intracoastal Waterway development. These findings have important management implications as they emphasize the role of habitat and the consequence of its modification in shaping bottlenose dolphin population structure and highlight the possibility of multiple management units existing in discrete inshore habitats along the entire eastern US shoreline.
Indian River Lagoon; microsatellite; mtDNA; Tursiops truncatus
We report here the development of 65 novel microsatellite loci and construction of a composite genetic linkage map for Culex pipiens complex mosquitoes. Microsatellites were identified by in silico screening of the Culex quinquefasciatus genome assembly. Cross-species utility of 73 microsatellites for population studies in C. pipiens sensu stricto and C. quinquefasciatus was evaluated by genotyping a subset of samples collected in Indiana, United States, and Point Fortin, Trinidad. Allele frequencies of 67 microsatellites were within Hardy–Weinberg expectations in both population subsets. A composite linkage map was constructed based on restriction fragment length polymorphism and microsatellite polymorphisms in 12 independent F1 intercross mapping populations. The composite map consists of 61 marker loci totaling 183.9 cM distributed across the 3 linkage groups. These loci cover 29.5, 88.8, and 65.6 cM on chromosomes I–III, respectively, and allow for assignment of 10.4% of the genome assembly and 13.5% of the protein coding genes to chromosome position. Our results suggest that these microsatellites will be useful for mapping and population studies of 2 pervasive species in the C. pipiens complex. Moreover, the composite map presented here will serve as a basis for the construction of high-resolution genetic and physical maps, as well as detection of quantitative trait loci to aid in the investigation of complex genetic traits influencing phenotypes of interest.
composite linkage map; Culex quinquefasciatus; genome assembly; house mosquito; SSR; supercontigs
Current advances in plant genotyping lead to major progress in the knowledge of genetic architecture of traits of interest. It is increasingly important to develop decision support tools to help breeders and geneticists to conduct marker-assisted selection methods to assemble favorable alleles that are discovered. Algorithms have been implemented, within an interactive graphical interface, to 1) trace parental alleles throughout generations, 2) propose strategies to select the best plants based on estimated molecular scores, and 3) efficiently intermate them depending on the expected value of their progenies. With the possibility to consider a multi-allelic context, OptiMAS opens new prospects to assemble favorable alleles issued from diverse parents and further accelerate genetic gain.
marker-assisted selection; plant breeding; QTL; multiparental designs; gene pyramiding
G protein–coupled receptor 84 (GPR84) is a 7-transmembrane protein expressed on myeloid cells that can bind to medium-chain free fatty acids in vitro. Here, we report the discovery of a 2-bp frameshift deletion in the second exon of the Gpr84 gene in several classical mouse inbred strains. This deletion generates a premature stop codon predicted to result in a truncated protein lacking the transmembrane domains 4-7. We sequenced Gpr84 exon 2 from 58 strains representing different groups in the mouse family tree and found that 14 strains are homozygous for the deletion. Some of these strains are DBA/1J, DBA/2J, FVB/NJ, LG/J, MRL/MpJ, NOD/LtJ, and SJL/J. However, the deletion was not found in any of the wild-derived inbred strains analyzed. Haplotype analysis suggested that the deletion originates from a unique mutation event that occurred more than 100 years ago, preceding the development of the first inbred strain (DBA), from a Mus musculus domesticus source. As GPR84 ostensibly plays a role in the biology of myeloid cells, it could be relevant 1) to consider the existence of this Gpr84 nonsense mutation in several mouse strains when choosing a mouse model to study immune processes and 2) to consider reevaluating data obtained using such strains.
spontaneous mutations; G protein–coupled receptors; inbred mice; mouse models
A long-standing question in evolutionary biology is how sexual reproduction has persisted in eukaryotic lineages. As cyclical parthenogens, monogonont rotifers are a powerful model for examining this question, yet the molecular nature of sexual reproduction in this lineage is currently understudied. To examine genes involved in meiosis, we generated partial genome assemblies for 2 distantly related monogonont species, Brachionus calyciflorus and B. manjavacas. Here we present an inventory of 89 meiotic genes, of which 80 homologs were identified and annotated from these assemblies. Using phylogenetic analysis, we show that several meiotic genes have undergone relatively recent duplication events that appear to be specific to the monogonont lineage. Further, we compare the expression of “meiosis-specific” genes involved in recombination and all annotated copies of the cell cycle regulatory gene CDC20 between obligate parthenogenetic (OP) and cyclical parthenogenetic (CP) strains of B. calyciflorus. We show that “meiosis-specific” genes are expressed in both CP and OP strains, whereas the expression of one of the CDC20 genes is specific to cyclical parthenogenesis. The data presented here provide insights into mechanisms of cyclical parthenogenesis and establish expectations for studies of obligate asexual relatives of monogononts, the bdelloid rotifer lineage.
asexual reproduction; cyclical parthenogenesis; evolution of sex
Captive breeding and rearing are central elements in conservation, management, and recovery planning for many endangered species including Rio Grande Silvery Minnow, a North American freshwater cyprinid. Traditionally, the sole purpose of hatcheries was to produce as many fish as feasible for stocking and harvest. Production quotas are also an important consideration in hatchery programs for endangered species, but they must also maintain and maximize genetic diversity of fish produced through implementation of best breeding practices. Here, we assessed genetic outcomes and measures of productivity (number of eggs and larval viability) for three replicates of three mating designs that are used for this small, pelagic-spawning fish. These were 1) monogamous mating, 2) hormone-induced communal spawning, and 3) environmentally cued communal spawning. A total of 180 broodstock and 450 progeny were genotyped. Genetic diversity and egg productivity did not differ significantly among spawning designs (H
e: F = 0.52, P = 0.67; H
o: F = 0.12, P = 0.89; number of eggs: F = 3.59, P = 0.09), and there was evidence for variance in reproductive success among individuals in all three designs. Allelic richness declined from the broodstock to progeny generation in all breeding designs. There was no significant difference in the genetic effective size (regardless of the method used) among designs. Significantly more viable eggs were produced in environmentally cued communal spawn compared to the alternative strategies (F = 5.72, P = 0.04), but this strategy is the most difficult to implement.
captive spawning; effective population size; genetic diversity; Rio Grande Silvery Minnow
The tf (tufted) locus is responsible for a classic phenotype of hair loss and regrowth in mice. It is a characteristic of the BTBR strain. Here, we use a combination of positional cloning methods and complementation mapping to identify Itpr3, the inositol triphosphate receptor type 3, as the gene responsible for the tf locus.
BTBR mouse; hair; inosine triphosphate receptor type 3
Variation patterns of allozymes and of ND3 haplotypes of mitochondrial DNA reveal a zone of genetic transition among western Palearctic water frogs extending across northeastern Greece and European Turkey. At the western end of the zone, allozymes characteristic of Central European frogs known as Pelophylax ridibundus predominate, whereas at the eastern end, alleles characteristic of western Anatolian water frogs (P. cf. bedriagae) prevail. The ND3 haplotypes reveal 2 major clades, 1 characteristic of Anatolian frogs, the other of European; the European clade itself has distinct eastern and western subclades. Both the 2 major clades and the 2 subclades overlap within the transition zone. Using Bayesian model selection methods, allozyme data suggest considerable immigration into the Nestos River area from eastern and western populations. In contrast, the ND3 data suggest that migration rates are so high among all locations that they form a single panmictic unit; the best model for allozymes is second best for mitochondrial DNA (mtDNA). Nuclear markers (allozymes), which have roughly 4 times as deep a coalescent history as mtDNA data and thus may reflect patterns over a longer time, indicate that eastern and western refugial populations have expanded since deglaciation (in the last 10 000 years) and have met near the Nestos River, whereas the mtDNA with its smaller effective population size has already lost the signal of partitioning into refugia.
allozymes; Bayes factors; gene flow; hybridization; migration; mitochondrial DNA; model selection; Pelophylax; sympatry; water frogs
Genetic datasets can be used to date evolutionary events, even on recent time scales if sufficient data are available. We used statistics calculated from multilocus microsatellite datasets to estimate population ages in data generated through coalescent simulations and in samples from populations of known age in a metapopulation of Daphnia magna in Finland. Our simulation results show that age estimates improve with additional loci and define a time frame over which these statistics are most useful. On the most recent time scales, assumptions regarding the model of mutation (infinite sites vs. stepwise mutation) have little influence on estimated ages. In older populations, size homoplasy among microsatellite alleles results in a downwards bias for estimates based on the infinite sites model (ISM). In the Finnish D. magna metapopulation, our genetically derived estimated ages were biased upwards. Potential sources of this bias include the underlying model of mutation, gene flow, founder size, and the possibility of persistent source populations in the system. Our simulated data show that genetic age estimation is possible, even for very young populations, but our empirical data highlight the importance of factors such as migration when these statistics are applied in natural populations.
colonization; distribution; metapopulation; microsatellites; mismatch; population expansion
Rexoid, curly hair mutations have been selected to develop new domestic cat breeds. The Selkirk Rex is the most recently established curly-coated cat breed originating from a spontaneous mutation that was discovered in the United States in 1987. Unlike the earlier and well-established Cornish and Devon Rex breeds with curly-coat mutations, the Selkirk Rex mutation is suggested as autosomal dominant and has a different curl phenotype. This study provides a genetic analysis of the Selkirk Rex breed. An informal segregation analysis of genetically proven matings supported an autosomal, incomplete dominant expression of the curly trait in the Selkirk Rex. Homozygous curl cats can be distinguished from heterozygous cats by head and body type, as well as the presentation of the hair curl. Bayesian clustering of short tandem repeat (STR) genotypes from 31 cats that represent the future breeding stock supported the close relationship of the Selkirk Rex to the British Shorthair, Scottish Fold, Persian, and Exotic Shorthair, suggesting the Selkirk as part of the Persian breed family. The high heterozygosity of 0.630 and the low mean inbreeding coefficient of 0.057 suggest that Selkirk Rex has a diverse genetic foundation. A new locus for Selkirk autosomal dominant Rex, SADRE, is suggested for the curly trait.
curly; dominant; feline; hair