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Human evolutionary genetics

Zhangxia Lyu, Jingru Shao, Min Xue, Qingqing Ye, Bing Chen, Yan Qin, Jianfan Wen
BACKGROUND: Giardia spp. are flagellated protozoan parasites that infect humans and many other vertebrates worldwide. Currently seven species of Giardia are considered valid. RESULTS: Here, we report a new species, Giardia cricetidarum n. sp. in hamsters. Trophozoites of G. cricetidarum n. sp. are pear-shaped with four pairs of flagella and measure on average 14 μm (range 12-18 μm) in length and 10 μm (range 8-12 μm) in width. The trophozoites of the new species are generally larger and stouter than those of most of the other Giardia spp...
March 20, 2018: Parasites & Vectors
Akim Felipe Santos Nobre, Danilo de Souza Almeida, Louise Canto Ferreira, Deimy Lima Ferreira, Edivaldo Costa Sousa Júnior, Maria de Nazaré do Socorro de Almeida Viana, Ingrid Christiane Silva, Bruna Teles Pinheiro, Stephen Francis Ferrari, Alexandre da Costa Linhares, Edna Aoba Ishikawa, Rita Catarina Medeiros Sousa, Maísa Silva de Sousa
The Human T-cell Lymphotropic Virus (HTLV-1) is a Deltaretrovírus that was first isolated in the 1970s, and associated with Adult T-cell Leucemia-Lymphoma (ATLL), and subsequently to Tropical Spastic Paraparesis-Myelopathy (TSP/HAM). The genetic diversity of the virus varies among geographic regions, although its mutation rate is very low (approximately 1% per thousand years) in comparison with other viruses. The present study determined the genetic diversity of HTLV-1 in the metropolitan region of Belém, in northern Brazil...
2018: PloS One
Chen Zhu, Xiaohui Zhang, Qiran Zhao, Qihui Chen
In genetics, heterosis refers to the phenomenon that cross-breeding within species leads to offspring that are genetically fitter than their parents and exhibit improved phenotypic characteristics. Based on the theory of heterosis and existing genetic evidence, offspring of "hybrid" marriages (spouses originating from different states/provinces/countries/areas), though relatively rare due to physical boundaries, may exhibit greater genetic fitness in terms of intelligence, height, or physical attractiveness (the "distance-performance" hypothesis)...
February 19, 2018: Economics and Human Biology
Oneida Espinosa-Álvarez, Paola A Ortiz, Luciana Lima, André G Costa-Martins, Myrna G Serrano, Stephane Herder, Gregory A Buck, Erney P Camargo, Patrick B Hamilton, Jamie R Stevens, Marta M G Teixeira
Trypanosoma rangeli and Trypanosoma cruzi are generalist trypanosomes sharing a wide range of mammalian hosts; they are transmitted by triatomine bugs, and are the only trypanosomes infecting humans in the Neotropics. Their origins, phylogenetic relationships, and emergence as human parasites have long been subjects of interest. In the present study, taxon-rich analyses (20 trypanosome species from bats and terrestrial mammals) using ssrRNA, glycosomal glyceraldehyde-3-phosphate dehydrogenase (gGAPDH), heat shock protein-70 (HSP70) and Spliced Leader (SL) RNA sequences, and multilocus phylogenetic analyses using 11 single copy genes from 15 selected trypanosomes, provide increased resolution of relationships between species and clades, strongly supporting two main sister lineages: lineage Schizotrypanum, comprising T...
March 12, 2018: International Journal for Parasitology
Jacob W P Potuijt, Martijn Baas, Rivka Sukenik-Halevy, Hannie Douben, Picard Nguyen, Deon J Venter, Renée Gallagher, Sigrid M Swagemakers, Steven E R Hovius, Christianne A van Nieuwenhoven, Robert-Jan H Galjaard, Peter J van der Spek, Nadav Ahituv, Annelies de Klein
PurposeThe zone of polarizing activity regulatory sequence (ZRS) is an enhancer that regulates sonic hedgehog during embryonic limb development. Recently, mutations in a noncoding evolutionary conserved sequence 500 bp upstream of the ZRS, termed the pre-ZRS (pZRS), have been associated with polydactyly in dogs and humans. Here, we report the first case of triphalangeal thumb-polysyndactyly syndrome (TPT-PS) to be associated with mutations in this region and show via mouse enhancer assays how this mutation leads to ectopic expression throughout the developing limb bud...
March 15, 2018: Genetics in Medicine: Official Journal of the American College of Medical Genetics
M G Carta, A Preti, H S Akiskal
Human population is increasing in immense cities with millions of inhabitants, in which life is expected to run 24 hours a day for seven days a week (24/7). Noise and light pollution are the most reported consequences, with a profound impact on sleep patterns and circadian biorhythms. Disruption of sleep and biorhythms has severe consequences on many metabolic pathways. Suppression of melatonin incretion at night and the subsequent effect on DNA methylation may increase the risk of prostate and breast cancer...
2018: Clinical Practice and Epidemiology in Mental Health: CP & EMH
François Ancien, Fabrizio Pucci, Maxime Godfroid, Marianne Rooman
The classification of human genetic variants into deleterious and neutral is a challenging issue, whose complexity is rooted in the large variety of biophysical mechanisms that can be responsible for disease conditions. For non-synonymous mutations in structured proteins, one of these is the protein stability change, which can lead to loss of protein structure or function. We developed a stability-driven knowledge-based classifier that uses protein structure, artificial neural networks and solvent accessibility-dependent combinations of statistical potentials to predict whether destabilizing or stabilizing mutations are disease-causing...
March 14, 2018: Scientific Reports
Katherine S Xue, Louise H Moncla, Trevor Bedford, Jesse D Bloom
The rapid global evolution of influenza virus begins with mutations that arise de novo in individual infections, but little is known about how evolution occurs within hosts. We review recent progress in understanding how and why influenza viruses evolve within human hosts. Advances in deep sequencing make it possible to measure within-host genetic diversity in both acute and chronic influenza infections. Factors like antigenic selection, antiviral treatment, tissue specificity, spatial structure, and multiplicity of infection may affect how influenza viruses evolve within human hosts...
March 10, 2018: Trends in Microbiology
Wen-Yong Guo, Carla Lambertini, Petr Pyšek, Laura A Meyerson, Hans Brix
Identifying the factors that influence spatial genetic structure among populations can provide insights into the evolution of invasive plants. In this study, we used the common reed ( Phragmites australis ), a grass native in Europe and invading North America, to examine the relative importance of geographic, environmental (represented by climate here), and human effects on population genetic structure and its changes during invasion. We collected samples of P. australis from both the invaded North American and native European ranges and used molecular markers to investigate the population genetic structure within and between ranges...
March 2018: Ecology and Evolution
Marie Lopez, Athanasios Kousathanas, Hélène Quach, Christine Harmant, Patrick Mouguiama-Daouda, Jean-Marie Hombert, Alain Froment, George H Perry, Luis B Barreiro, Paul Verdu, Etienne Patin, Lluís Quintana-Murci
Understanding how deleterious genetic variation is distributed across human populations is of key importance in evolutionary biology and medical genetics. However, the impact of population size changes and gene flow on the corresponding mutational load remains a controversial topic. Here, we report high-coverage exomes from 300 rainforest hunter-gatherers and farmers of central Africa, whose distinct subsistence strategies are expected to have impacted their demographic pasts. Detailed demographic inference indicates that hunter-gatherers and farmers recently experienced population collapses and expansions, respectively, accompanied by increased gene flow...
March 12, 2018: Nature Ecology & Evolution
Simonetta Mattiucci, Paolo Cipriani, Arne Levsen, Michela Paoletti, Giuseppe Nascetti
This review addresses the biodiversity, biology, distribution, ecology, epidemiology, and consumer health significance of the so far known species of Anisakis, both in their natural hosts and in human accidental host populations, worldwide. These key aspects of the Anisakis species' biology are highlighted, since we consider them as main driving forces behind which most of the research in this field has been carried out over the past decade. From a public health perspective, the human disease caused by Anisakis species (anisakiasis) appears to be considerably underreported and underestimated in many countries or regions around the globe...
2018: Advances in Parasitology
Geromy G Moore, Brian M Mack, Shannon B Beltz, Olivier Puel
BACKGROUND: Aspergillus arachidicola is an aflatoxigenic fungal species, first isolated from the leaves of a wild peanut species native to Argentina. It has since been reported in maize, Brazil nut and human sputum samples. This aflatoxigenic species is capable of secreting both B and G aflatoxins, similar to A. parasiticus and A. nomius. It has other characteristics that may result in its misidentification as one of several other section Flavi species. This study offers a preliminary analysis of the A...
March 9, 2018: BMC Genomics
S Y Kovalev, S Zh Fedorova, T A Mukhacheva
Ticks of the Ixodes ricinus group are important vectors of human pathogens in both Eurasia and North America; therefore, many studies have focused on their molecular systematics and evolutionary relationships. However, there are species that have not been characterized by molecular genetic methods so far. For the first time, we obtained nucleotide sequences of two nuclear and three mitochondrial genetic markers from four museum specimen of I. kazakstani Olenev et Sorokoumov, 1934, collected in Kyrgyzstan. The phylogenetic analysis showed that I...
March 5, 2018: Ticks and Tick-borne Diseases
John R Speakman
Human obesity has a large genetic component, yet has many serious negative consequences. How this state of affairs has evolved has generated wide debate. The thrifty gene hypothesis was the first attempt to explain obesity as a consequence of adaptive responses to an ancient environment that in modern society become disadvantageous. The idea is that genes (or more precisely, alleles) predisposing to obesity may have been selected for by repeated exposure to famines. However, this idea has many flaws: for instance, selection of the supposed magnitude over the duration of human evolution would fix any thrifty alleles (famines kill the old and young, not the obese) and there is no evidence that hunter-gatherer populations become obese between famines...
March 7, 2018: Journal of Experimental Biology
Ryan C Shean, Alexander L Greninger
Infectious pathogens are known for their rapid evolutionary rates with new mutations arising over days to weeks. The ability to rapidly recover whole genome sequences and analyze the spread and evolution of pathogens using genetic information and pathogen collection dates has lead to interest in real-time tracking of infectious transmission and outbreaks. However, the level of temporal resolution afforded by these analyses may conflict with definitions of what constitutes protected health information (PHI) and privacy requirements for de-identification for publication and public sharing of research data and metadata...
January 2018: Virus Evolution
Timothy D Weaver, Philipp Gunz
Researchers studying extant and extinct taxa are often interested in identifying the evolutionary processes that have lead to the morphological differences among the taxa. Ideally, one could distinguish the influences of neutral evolutionary processes (genetic drift, mutation) from natural selection, and in situations for which selection is implicated, identify the targets of selection. The directional selection gradient is an effective tool for investigating evolutionary process, because it can relate form (size and shape) differences between taxa to the variation and covariation found within taxa...
March 6, 2018: Evolution; International Journal of Organic Evolution
Jing-Wen Meng, Dun-Chun He, Wen Zhu, Li-Na Yang, E-Jiao Wu, Jia-Hui Xie, Li-Ping Shang, Jiasui Zhan
Metapopulation structure generated by recurrent extinctions and recolonizations plays an important role in the evolution of species but is rarely considered in agricultural systems. In this study, generation and mechanism of metapopulation structure were investigated by microsatellite assaying 725 isolates of Alternaria alternata sampled from potato hosts at 16 locations across China. We found a single major cluster, no isolate-geography associations and no bottlenecks in the A. alternata isolates, suggesting a metapopulation genetic structure of the pathogen...
2018: Frontiers in Plant Science
Ning-Ning Zhang, Jiao-Jun Yu, Yue-Hua Wang, Xun Gong
Natural hybridization is common in plants and results in different evolutionary consequences to hybridizing species. Pre- and post-zygotic reproductive isolating barriers can impede hybridization between closely related species to maintain their species integrity. In Northwest Yunnan, three Ligularia species ( Ligularia cyathiceps , L. duciformis and L. yunnanensis ) and four types of morphologically intermediate individuals were discovered growing together in an area subject to human disturbance. In this study, we used three low-copy nuclear loci to test the natural hybridization hypothesis and the hybridization direction was ascertained by three chloroplast DNA fragments...
February 2018: AoB Plants
T C Goldsmith
Programmed (adaptive) aging refers to the idea that mammals, including humans and other complex organisms, have evolved mechanisms that purposely cause or allow senescence or otherwise internally limit their lifespans in order to obtain an evolutionary advantage. Until recently, programmed aging had been thought to be theoretically impossible because of the mechanics of the evolution process. However, there is now substantial theoretical and empirical support for the existence of programmed aging in mammals...
December 2017: Biochemistry. Biokhimii︠a︡
T C Goldsmith
Programmed aging theories contend that evolved biological mechanisms purposely limit internally determined lifespans in mammals and are ultimately responsible for most instances of highly age-related diseases and conditions. Until recently, the existence of programmed aging mechanisms was considered theoretically impossible because it directly conflicted with Darwin's survival-of-the-fittest evolutionary mechanics concept as widely taught and generally understood. However, subsequent discoveries, especially in genetics, have exposed issues with some details of Darwin's theory that affect the mechanics of the evolution process and strongly suggest that programmed aging mechanisms in humans and other mammals can and did evolve, and more generally, that a trait that benefits a population can evolve even if, like senescence, it is adverse to individual members of the population...
December 2017: Biochemistry. Biokhimii︠a︡
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