Is increased mutation driving genetic diversity in dogs within the Chornobyl exclusion zone?

Environmental contamination can have lasting impacts on surrounding communities, though the long-term impacts can be difficult to ascertain. The disaster at the Chornobyl Nuclear Power Plant in 1986 and subsequent remediation efforts resulted in contamination of the local environment with radioactive material, heavy metals, and additional environmental toxicants. Many of these are mutagenic in nature, and the full effect of these exposures on local flora and fauna has yet to be understood.

Distinct genetic origins of eumelanin levels and barring patterns in cichlid fishes.

Pigment patterns are incredibly diverse across vertebrates and are shaped by multiple selective pressures from predator avoidance to mate choice. A common pattern across fishes, but for which we know little about the underlying mechanisms, is repeated melanic vertical bars. To understand the genetic factors that modify the level or pattern of vertical barring, we generated a genetic cross of 322 F2 hybrids between two cichlid species with distinct barring patterns, Aulonocara koningsi and Metriaclima mbenjii.

Distinct genetic origins of eumelanin intensity and barring patterns in cichlid fishes.

Pigment patterns are incredibly diverse across vertebrates and are shaped by multiple selective pressures from predator avoidance to mate choice. A common pattern across fishes, but for which we know little about the underlying mechanisms, is repeated melanic vertical bars. In order to understand genetic factors that modify the level or pattern of vertical barring, we generated a genetic cross of 322 F hybrids between two cichlid species with distinct barring patterns, and .

Genetic basis of ecologically relevant body shape variation among four genera of cichlid fishes.

Divergence in body shape is one of the most widespread and repeated patterns of morphological variation in fishes and is associated with habitat specification and swimming mechanics. Such ecological diversification is the first stage of the explosive adaptive radiation of cichlid fishes in the East African Rift Lakes. We use two hybrid crosses of cichlids (Metriaclima sp.

Morphometric and Genetic Description of Trophic Adaptations in Cichlid Fishes.

Since Darwin, biologists have sought to understand the evolution and origins of phenotypic adaptations. The skull is particularly diverse due to intense natural selection on feeding biomechanics. We investigated the genetic and molecular origins of trophic adaptation using Lake Malawi cichlids, which have undergone an exemplary evolutionary radiation.

Polygenic sex determination produces modular sex polymorphism in an African cichlid fish.

For many vertebrates, a single genetic locus initiates a cascade of developmental sex differences in the gonad and throughout the organism, resulting in adults with two phenotypically distinct sexes. Species with polygenic sex determination (PSD) have multiple interacting sex determination alleles segregating within a single species, allowing for more than two genotypic sexes and scenarios where sex genotype at a given locus can be decoupled from gonadal sex. Here we investigate the effects of PSD on secondary sexual characteristics in the cichlid fish Metriaclima mbenjii, where one female (W) and one male (Y) sex determination allele interact to produce siblings with four possible sex classes: ZZXX females, ZWXX females, ZWXY females, and ZZXY males.

Spectral Decomposition of the Flow and Characterization of the Sound Signals through Stenoses with Different Levels of Severity.

Treatments of atherosclerosis depend on the severity of the disease at the diagnosis time. Non-invasive diagnosis techniques, capable of detecting stenosis at early stages, are essential to reduce associated costs and mortality rates. We used computational fluid dynamics and acoustics analysis to extensively investigate the sound sources arising from high-turbulent fluctuating flow through stenosis.

Spectral Decomposition and Sound Source Localization of Highly Disturbed Flow through a Severe Arterial Stenosis.

For the early detection of atherosclerosis, it is imperative to explore the capabilities of new, effective noninvasive diagnosis techniques to significantly reduce the associated treatment costs and mortality rates. In this study, a multifaceted comprehensive approach involving advanced computational fluid dynamics combined with signal processing techniques was exploited to investigate the highly turbulent fluctuating flow through arterial stenosis. The focus was on localizing high-energy mechano-acoustic source potential to transmit to the epidermal surface.

Origin of a Giant Sex Chromosome.

Chromosome size and morphology vary within and among species, but little is known about the proximate or ultimate causes of these differences. Cichlid fish species in the tribe Oreochromini share an unusual giant chromosome that is ∼3 times longer than the other chromosomes. This giant chromosome functions as a sex chromosome in some of these species.

Chromosome-scale assemblies reveal the structural evolution of African cichlid genomes.

Background: African cichlid fishes are well known for their rapid radiations and are a model system for studying evolutionary processes. Here we compare multiple, high-quality, chromosome-scale genome assemblies to elucidate the genetic mechanisms underlying cichlid diversification and study how genome structure evolves in rapidly radiating lineages.

Results: We re-anchored our recent assembly of the Nile tilapia (Oreochromis niloticus) genome using a new high-density genetic map.

The intestinal environment as an evolutionary adaptation to mouthbrooding in the Astatotilapia burtoni cichlid.

Many of the various parental care strategies displayed by animals are accompanied by a significant reduction in food intake that imposes a substantial energy trade-off. Mouthbrooding, as seen in several species of fish in which the parent holds the developing eggs and fry in the buccal cavity, represents an extreme example of reduced food intake during parental investment and is accompanied by a range of physiological adaptations. In this study we use 16S sequencing to characterize the gut microbiota of female Astatotilapia burtoni cichlid fish throughout the obligatory phase of self-induced starvation during the brooding cycle in comparison to stage-matched females that have been denied food for the same duration.

Genetic sex determination in Astatotilapia calliptera, a prototype species for the Lake Malawi cichlid radiation.

East African cichlids display extensive variation in sex determination systems. The species Astatotilapia calliptera is one of the few cichlids that reside both in Lake Malawi and in surrounding waterways. A.

An allelic series at pax7a is associated with colour polymorphism diversity in Lake Malawi cichlid fish.

Despite long-standing interest in the evolution and maintenance of discrete phenotypic polymorphisms, the molecular genetic basis of such polymorphism in the wild is largely unknown. Female sex-associated blotched colour polymorphisms found in cichlids of Lake Malawi, East Africa, represent a highly successful polymorphic phenotype, found and maintained in four genera across the geographic expanse of the lake. Previously, we identified an association with an allelic variant of the paired-box transcription factor gene pax7a and blotched colour morphs in Lake Malawi cichlid fishes.

Polygenic sex determination in the cichlid fish Astatotilapia burtoni.

Background: The East African riverine cichlid species Astatotilapia burtoni serves as an important laboratory model for sexually dimorphic physiology and behavior, and also serves as an outgroup species for the explosive adaptive radiations of cichlid species in Lake Malawi and Lake Victoria. An astounding diversity of genetic sex determination systems have been revealed within the adaptive radiation of East African cichlids thus far, including polygenic sex determination systems involving the epistatic interaction of multiple, independently segregating sex determination alleles. However, sex determination has remained unmapped in A.

Development of a universal double-digest RAD sequencing approach for a group of nonmodel, ecologically and economically important insect and fish taxa.

The generation of genome-scale data is critical for a wide range of questions in basic biology using model organisms, but also in questions of applied biology in nonmodel organisms (agriculture, natural resources, conservation and public health biology). Using a genome-scale approach on a diverse group of nonmodel organisms and with the goal of lowering costs of the method, we modified a multiplexed, high-throughput genomic scan technique utilizing two restriction enzymes. We analysed several pairs of restriction enzymes and completed double-digestion RAD sequencing libraries for nine different species and five genera of insects and fish.

Structure and decay of a proto-Y region in Tilapia, Oreochromis niloticus.

Background: Sex-determination genes drive the evolution of adjacent chromosomal regions. Sexually antagonistic selection favors the accumulation of inversions that reduce recombination in regions adjacent to the sex-determination gene. Once established, the clonal inheritance of sex-linked inversions leads to the accumulation of deleterious alleles, repetitive elements and a gradual decay of sex-linked genes.

Genetic basis of continuous variation in the levels and modular inheritance of pigmentation in cichlid fishes.

Variation in pigmentation type and levels is a hallmark of myriad evolutionary radiations, and biologists have long been fascinated by the factors that promote and maintain variation in coloration across populations. Here, we provide insights into the genetic basis of complex and continuous patterns of colour variation in cichlid fishes, which offer a vast diversity of pigmentation patterns that have evolved in response to both natural and sexual selection. Specifically, we crossed two divergent cichlid species to generate an F2 mapping population that exhibited extensive variation in pigmentation levels and patterns.

Origins of shared genetic variation in African cichlids.

Cichlid fishes have evolved tremendous morphological and behavioral diversity in the waters of East Africa. Within each of the Great Lakes Tanganyika, Malawi, and Victoria, the phenomena of hybridization and retention of ancestral polymorphism explain allele sharing across species. Here, we explore the sharing of single nucleotide polymorphisms (SNPs) between the major East African cichlid assemblages.

A small number of genes underlie male pigmentation traits in Lake Malawi cichlid fishes.

Pigmentation patterns are one of the most recognizable forms of phenotypic diversity and an important component of organismal fitness. While much progress has been made in understanding the genes controlling pigmentation in model systems, many questions remain about the genetic basis of pigment traits observed in nature. Lake Malawi cichlid fishes are known for their diversity of male pigmentation patterns, which have been shaped by sexual selection.

Craniofacial divergence and ongoing adaptation via the hedgehog pathway.

Adaptive variation in craniofacial structure contributes to resource specialization and speciation, but the genetic loci that underlie craniofacial adaptation remain unknown. Here we show that alleles of the hedgehog pathway receptor Patched1 (Ptch1) gene are responsible for adaptive variation in the shape of the lower jaw both within and among genera of Lake Malawi cichlid fish. The evolutionarily derived allele of Ptch1 reduces the length of the retroarticular (RA) process of the lower jaw, a change predicted to increase speed of jaw rotation for improved suction-feeding.

Molecular characterization and antibiotic susceptibility of Staphylococcus aureus from a multidisciplinary hospital in Romania.

From 2004 to 2005, 60%-72% of invasive Staphylococcus aureus isolates from Romanian hospitals were resistant to methicillin (methicillin-resistant S. aureus [MRSA]), the highest frequency for any European nation. Few reports, however, have addressed the molecular characteristics of S.

Identification of a novel transposon (Tn6072) and a truncated staphylococcal cassette chromosome mec element in methicillin-resistant Staphylococcus aureus ST239.

A novel composite transposon (Tn6072) resembling staphylococcal cassette chromosome mercury (SCCHg) was identified in a collection of sequence type (ST) 239 methicillin (meticillin)-resistant Staphylococcus aureus (MRSA) isolates from Romanian hospitals. Tn6072 is homologous to the 5' region of SCCHg found in staphylococcal cassette chromosome mec (SCCmec) type III prototype strain 85/2082 but lacks the characteristic mer operon. SCCHg has previously been reported to integrate downstream of orfX, at the same chromosomal location as SCCmec.