scholarly journals Enabling inference for context-dependent models of mutation by bounding the propagation of dependency

2021 ◽  
Author(s):  
Erick Matsen ◽  
Peter L. Ralph
Keyword(s):  
Bayesian Inference ◽  
Maximum Likelihood ◽  
Common Ancestor ◽  
Phylogenetic Inference ◽  
R Package ◽  
Flanking Sequence ◽  
Model Refinement ◽  
Iterative Model ◽  
The Common ◽  
Context Dependent

Although the rates at which positions in the genome mutate are known to depend not only on the nucleotide to be mutated, but also on neighboring nucleotides, it remains challenging to do phylogenetic inference using models of context-dependent mutation. In these models, the effects of one mutation may in principle propagate to faraway locations, making it difficult to compute exact likelihoods. This paper shows how to use bounds on the propagation of dependency to compute likelihoods of mutation of a given segment of genome by marginalizing over sufficiently long flanking sequence. This can be used for maximum likelihood or Bayesian inference. Protocols examining residuals and iterative model refinement are also discussed. Tools for efficiently working with these models are provided in an R package, that could be used in other applications. The method is used to examine context dependence of mutations since the common ancestor of humans and chimpanzee.

scholarly journals Molecular phylogeny of common sun skink, Eutropis (Squamata: Scincidae), of northwestern part of Bangladesh

2019 ◽  
Vol 47 (1) ◽  
pp. 13-25
Author(s):  
Mosharrof Hossain ◽  
Che Jing
Keyword(s):  
Bayesian Inference ◽  
Maximum Likelihood ◽  
16S Rrna ◽  
Molecular Phylogeny ◽  
Posterior Probability ◽  
Common Ancestor ◽  
Northwestern Part ◽  
Congeneric Species ◽  
Relationship Of ◽  
Posterior Probability Support

A study on the phylogenetic relationship of Bangladeshi Skink confirmed species as Eutropis multifasciata by Bayesian inference (BI) (100%) and 98% node support to maximum likelihood (ML) tree topology, respectively. The sequence divergences between Eutropis multifasciata and other congeneric species were significant, ranging from 0.1 to 13.6% for 16S rRNA. Intraspecific genetic divergence within E. multifasciata was estimated 10.3%. E. multifasciata formed a distinct clade with high posterior probability support. This maiden study on Bangladeshi Skink results support that one monophyletic subgroup containing all specimens of E. multifasciata and all recently recognized E. multifasciata populations have evolved from one common ancestor. Bangladesh J. Zool. 47(1): 13-25, 2019

Molecular Phylogeny of Coprophanaeus (Megaphanaeus) d’Olsoufieff, 1924 (Coleoptera: Scarabaeidae: Scarabaeinae) and the position of C. bellicosus

2020 ◽  
Vol 51 (2) ◽  
pp. 241-255 ◽  
Author(s):  
Maria E. Maldaner ◽  
Fernando Z. Vaz-de-Mello ◽  
Daniela M. Takiya ◽  
Daniela C. Ferreira
Keyword(s):  
Bayesian Inference ◽  
Maximum Likelihood ◽  
Molecular Phylogeny ◽  
Maximum Parsimony ◽  
Phylogenetic Inference ◽  
Sister Group ◽  
Monophyletic Group ◽  
Valid Species ◽  
Nuclear Marker

Coprophanaeus (Megaphanaeus) d’Olsoufieff, 1924 has four valid species: C. lancifer (Linné, 1767), C. ensifer (Germar, 1821), C. bonariensis (Gory, 1844) and C. bellicosus (Olivier, 1789). However, authors disagree about the placement of C. bellicosus. Thus, our aims were (I) to test if Megaphanaeus is a monophyletic group and (II) verify to which subgenus C. bellicosus belongs. We sequenced three mitochondrial and one nuclear marker for ten Phanaeini species: COI (672bp), COI-II (1326bp), 16S (527bp) and 28S (994bp). For fifteen species we sequenced two markers, COI (681pb) and 16S (532pb). Both matrices were analyzed under three methods of phylogenetic inference: Maximum Parsimony, Maximum Likelihood, and Bayesian Inference. Megaphanaeus is here considered monophyletic including C. bellicosus as sister-group to (C. bonariensis (C. lancifer + C. ensifer)). All analyses recovered the non-monophyly of both C. lancifer and C. ensifer, because of a population of C. lancifer grouped with C. ensifer specimens.

scholarly journals A Chromosome-Based Model for Estimating the Number of Conserved Segments Between Pairs of Species From Comparative Genetic Maps

Genetics ◽  
2000 ◽  
Vol 154 (1) ◽  
pp. 323-332
Author(s):  
David Waddington ◽  
Anthea J Springbett ◽  
David W Burt
Keyword(s):  
Maximum Likelihood ◽  
Dna Sequences ◽  
Common Ancestor ◽  
Length Distribution ◽  
Genetic Maps ◽  
Segment Length ◽  
Syntenic Block ◽  
Comparative Maps

Abstract Comparative genetic maps of two species allow insights into the rearrangements of their genomes since divergence from a common ancestor. When the map details the positions of genes (or any set of orthologous DNA sequences) on chromosomes, syntenic blocks of one or more genes may be identified and used, with appropriate models, to estimate the number of chromosomal segments with conserved content conserved between species. We propose a model for the distribution of the lengths of unobserved segments on each chromosome that allows for widely differing chromosome lengths. The model uses as data either the counts of genes in a syntenic block or the distance between extreme members of a block, or both. The parameters of the proposed segment length distribution, estimated by maximum likelihood, give predictions of the number of conserved segments per chromosome. The model is applied to data from two comparative maps for the chicken, one with human and one with mouse.

scholarly journals stochprofML: stochastic profiling using maximum likelihood estimation in R

2021 ◽  
Vol 22 (1) ◽  
Author(s):  
Lisa Amrhein ◽  
Christiane Fuchs
Keyword(s):  
Maximum Likelihood ◽  
Cell Fate ◽  
Likelihood Estimation ◽  
R Package ◽  
Cell Populations ◽  
Simulation Studies ◽  
Likelihood Principle ◽  
Maximum Likelihood Principle ◽  
Molecular Expression ◽  
Mixed Samples

Abstract Background Tissues are often heterogeneous in their single-cell molecular expression, and this can govern the regulation of cell fate. For the understanding of development and disease, it is important to quantify heterogeneity in a given tissue. Results We present the R package stochprofML which uses the maximum likelihood principle to parameterize heterogeneity from the cumulative expression of small random pools of cells. We evaluate the algorithm’s performance in simulation studies and present further application opportunities. Conclusion Stochastic profiling outweighs the necessary demixing of mixed samples with a saving in experimental cost and effort and less measurement error. It offers possibilities for parameterizing heterogeneity, estimating underlying pool compositions and detecting differences between cell populations between samples.

The Possible Common Origin of tRNA and 5S rRNA

1983 ◽  
Vol 38 (5-6) ◽  
pp. 501-504 ◽  
Author(s):  
Mária Ujhelyi
Keyword(s):  
Common Ancestor ◽  
Common Origin ◽  
5S Rrna ◽  
Mitochondrial Trna ◽  
Trna Molecule ◽  
The Common

Seryl tRNA (anticodon GCU) from mammalian mito­chondria shows in comparison to other mitochondrial tRNAs additional special features differing from the generalized tRNA model. When arranged in the tradi­tional cloverleaf form, eight bases fall within the TΨC loop, and the entire dihydrouridine loop is lacking. This seryl tRNA molecule is therefore shorter than other tRNAs. It was originally thought to represent a mito­chondrial analogon of 5 S rRNA and its precise classifica­tion is still disputed. The present studies suggest that this mitochondrial tRNA represents a fossil molecule which is related to the common ancestor of the present tRNA and 5 S rRNA molecules.

scholarly journals Role of the Digestive Gland in Ink Production in Four Species of Sea Hares: An Ultrastructural Comparison

2013 ◽  
Vol 2013 ◽  
pp. 1-5 ◽  
Author(s):  
Jeffrey S. Prince ◽  
Paul Micah Johnson
Keyword(s):  
Digestive Gland ◽  
Common Ancestor ◽  
Aplysia Californica ◽  
Digestive Cell ◽  
Digestive Cells ◽  
Sea Hare ◽  
Red Algal ◽  
The Common ◽  
Algal Chloroplast

The ultrastructure of the digestive gland of several sea hare species that produce different colored ink (Aplysia californicaproduces purple ink,A. julianawhite ink,A. parvulaboth white and purple ink, whileDolabrifera dolabriferaproduces no ink at all) was compared to determine the digestive gland’s role in the diet-derived ink production process. Rhodoplast digestive cells and their digestive vacuoles, the site of digestion of red algal chloroplast (i.e., rhodoplast) inA. californica, were present and had a similar ultrastructure in all four species. Rhodoplast digestive cell vacuoles either contained a whole rhodoplast or fragments of one or were empty. These results suggest that the inability to produce colored ink in some sea hare species is not due to either an absence of appropriate digestive machinery, that is, rhodoplast digestive cells, or an apparent failure of rhodoplast digestive cells to function. These results also propose that the digestive gland structure described herein occurred early in sea hare evolution, at least in the common ancestor to the generaAplysiaandDolabrifera. Our data, however, do not support the hypothesis that the loss of purple inking is a synapomorphy of the white-ink-producing subgenusAplysia.

scholarly journals Sexual reproduction and genetic exchange in parasitic protists

Parasitology ◽  
2014 ◽  
Vol 142 (S1) ◽  
pp. S120-S127 ◽  
Author(s):  
GARETH D. WEEDALL ◽  
NEIL HALL
Keyword(s):  
Life Cycle ◽  
Genome Sequencing ◽  
Common Ancestor ◽  
Life Cycles ◽  
Animal Disease ◽  
Eukaryotic Evolution ◽  
Sequencing Technology ◽  
Parasite Reproduction ◽  
The Common ◽  
Higher Eukaryotes

SUMMARYA key part of the life cycle of an organism is reproduction. For a number of important protist parasites that cause human and animal disease, their sexuality has been a topic of debate for many years. Traditionally, protists were considered to be primitive relatives of the ‘higher’ eukaryotes, which may have diverged prior to the evolution of sex and to reproduce by binary fission. More recent views of eukaryotic evolution suggest that sex, and meiosis, evolved early, possibly in the common ancestor of all eukaryotes. However, detecting sex in these parasites is not straightforward. Recent advances, particularly in genome sequencing technology, have allowed new insights into parasite reproduction. Here, we review the evidence on reproduction in parasitic protists. We discuss protist reproduction in the light of parasitic life cycles and routes of transmission among hosts.

Xylodon bambusinus and X. xinpingensis spp. nov. (Hymenochaetales) from southern China

Phytotaxa ◽  
2021 ◽  
Vol 511 (3) ◽  
Author(s):  
XIANG MA ◽  
CHANG-LIN ZHAO
Keyword(s):  
New Species ◽  
Bayesian Inference ◽  
Maximum Likelihood ◽  
Growth Habit ◽  
Southern China ◽  
Phylogenetic Analyses ◽  
Molecular Data ◽  
Two New Species ◽  
Thin Walled ◽  
Inference Methods

Two new species, Xylodon bambusinus and X. xinpingensis, are proposed based on morphological and molecular evidences. Both species share the annual growth habit, resupinate basidiomata and monomitic hyphal system with clamped, colorless generative hyphae, smooth, thin-walled basidiospores, but X. bambusinus is characterized by the smooth to tuberculate hymenial surface, presence of capitate and fusiform cystidia, broad ellipsoid basidiospores, while X. xinpingensis by the reticulate hymenophore with cream hymenial surface, and subglobose basidiospores (4.5–6 × 3.5–5 µm). Sequences of ITS and LSU nrRNA gene regions of the studied samples were generated, and phylogenetic analyses were performed with maximum likelihood, maximum parsimony and Bayesian inference methods. The phylogenetic analyses based on molecular data of ITS and ITS+nLSU sequences showed that X. bambusinus was sister to X. subclavatus, while X. xinpingensis grouped with X. astrocystidiatus and X. paradoxus. The nLSU dataset revealed that X. bambusinus grouped with X. asperus and X. brevisetus with lower supports, and that X. xinpingensis grouped with X. astrocystidiatus and X. paradoxus and then with X. rimosissimus without supports. Both morphological and molecular evidences confirmed the placement of two new species in Xylodon. Description and figures from the new species and a key to the known species of Xylodon from China are presented.

Whole-genome analysis-based phylogeographic investigation of Streptococcus pneumoniae serotype 19A sequence type 320 isolates in Japan.

2021 ◽  
Author(s):  
Satoshi Nakano ◽  
Takao Fujisawa ◽  
Bin Chang ◽  
Yutaka Ito ◽  
Hideki Akeda ◽  
...  
Keyword(s):  
Common Ancestor ◽  
Sampling Bias ◽  
Health Concern ◽  
Recent Common Ancestor ◽  
Whole Genome ◽  
Whole Genome Analysis ◽  
Identification Rate ◽  
Most Recent Common Ancestor ◽  
The Common ◽  
The U.S

After the introduction of the seven-valent pneumococcal conjugate vaccine, the global spread of multidrug resistant serotype 19A-ST320 strains became a public health concern. In Japan, the main genotype of serotype 19A was ST3111, and the identification rate of ST320 was low. Although the isolates were sporadically detected in both adults and children, their origin remains unknown. Thus, by combining pneumococcal isolates collected in three nationwide pneumococcal surveillance studies conducted in Japan between 2008 and 2020, we analyzed 56 serotype 19A-ST320 isolates along with 931 global isolates, using whole-genome sequencing to uncover the transmission route of the globally distributed clone in Japan. The clone was frequently detected in Okinawa Prefecture, where the U.S. returned to Japan in 1972. Phylogenetic analysis demonstrated that the isolates from Japan were genetically related to those from the U.S.; therefore, the common ancestor may have originated in the U.S. In addition, Bayesian analysis suggested that the time to the most recent common ancestor of the isolates form Japan and the U.S. was approximately the 1990s to 2000, suggesting the possibility that the common ancestor could have already spread in the U.S. before the Taiwan 19F-14 isolate was first identified in a Taiwanese hospital in 1997. The phylogeographical analysis supported the transmission of the clone from the U.S. to Japan, but the analysis could be influenced by sampling bias. These results suggested the possibility that the serotype 19A-ST320 clone had already spread in the U.S. before being imported into Japan.

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