The detailed examination of the human ancient mitochondrial DNA using the Ion PGM™ System

Author(s):  
Masaki Hashiyada ◽  
Noboru Adachi ◽  
Atsushi Akane ◽  
Tomohiro Matsumoto ◽  
Sumitaka Yoshimura
2020 ◽  
Vol 4 (6) ◽  
Author(s):  
Vinicius S Ferreira ◽  
Oliver Keller ◽  
Marc A Branham

Abstract In this study, we describe a new Lampyridae subfamily, Chespiritoinae new subfamily, its sole genus Chespiritonew genus, and three new species: Chespirito zaragozainew species, Chespirito lloydinew species, and Chespirito ballantyneaenew species from the Neotropical portions of Mexico. Chespirito can be readily separated from all other known Lampyridae by the unique prosternum, characterized by being very wide, divided in the middle by a distinct suture forming two plates, with the anterior margin bearing a narrow inter-coxal process, the strongly setose filiform antennae, with antennomere III much smaller than all other antennomeres, the pronotum medially constricted (not in C. ballantyneae), with area adjacent to disc strongly punctate and with the presence of a strongly developed longitudinal carina. To test the placement of the genus within the Lampyridae, we obtained three genetic markers (18S rRNA, 28SrRNA, and cox1 mitochondrial DNA) from C. zaragozai and performed a maximum likelihood (ML) and Bayesian inference (BI) analysis. Our analyses rendered nearly identical tree topologies, with C. zaragozainew species recovered as an independent lineage as sister to Pollaclasis bifaria (Say) (Coleoptera, Lampyridae) + Cyphonocerus ruficollis Kiesenwetter (Coleoptera, Lampyridae)+Luciolinae, with a posterior probability of 96 for the BI analysis and UFBoot respectively of 91 for the ML analysis with the entire clade sister to Pterotus obscuripennis LeConte (Coleoptera, Lampyridae). A detailed examination of the morphology of Chespirito indicates that this lineage is divergent from all other known Lampyridae, which combined with the results of our analyses supports the erection of a new subfamily.


2018 ◽  
Vol 32 ◽  
pp. 27-30 ◽  
Author(s):  
Lan Yao ◽  
Zhen Xu ◽  
Hemiao Zhao ◽  
Zheng Tu ◽  
Zhifang Liu ◽  
...  

Author(s):  
Douglas C. Barker

A number of satisfactory methods are available for the electron microscopy of nicleic acids. These methods concentrated on fragments of nuclear, viral and mitochondrial DNA less than 50 megadaltons, on denaturation and heteroduplex mapping (Davies et al 1971) or on the interaction between proteins and DNA (Brack and Delain 1975). Less attention has been paid to the experimental criteria necessary for spreading and visualisation by dark field electron microscopy of large intact issociations of DNA. This communication will report on those criteria in relation to the ultrastructure of the (approx. 1 x 10-14g) DNA component of the kinetoplast from Trypanosomes. An extraction method has been developed to eliminate native endonucleases and nuclear contamination and to isolate the kinetoplast DNA (KDNA) as a compact network of high molecular weight. In collaboration with Dr. Ch. Brack (Basel [nstitute of Immunology), we studied the conditions necessary to prepare this KDNA Tor dark field electron microscopy using the microdrop spreading technique.


Author(s):  
K. S. McCarty ◽  
R. F. Weave ◽  
L. Kemper ◽  
F. S. Vogel

During the prodromal stages of sporulation in the Basidiomycete, Agaricus bisporus, mitochondria accumulate in the basidial cells, zygotes, in the gill tissues prior to entry of these mitochondria, together with two haploid nuclei and cytoplasmic ribosomes, into the exospores. The mitochondria contain prominent loci of DNA [Fig. 1]. A modified Kleinschmidt spread technique1 has been used to evaluate the DNA strands from purified whole mitochondria released by osmotic shock, mitochondrial DNA purified on CsCl gradients [density = 1.698 gms/cc], and DNA purified on ethidium bromide CsCl gradients. The DNA appeared as linear strands up to 25 u in length and circular forms 2.2-5.2 u in circumference. In specimens prepared by osmotic shock, many strands of DNA are apparently attached to membrane fragments [Fig. 2]. When mitochondria were ruptured in hypotonic sucrose and then fixed in glutaraldehyde, the ribosomes were released for electron microscopic examination.


Author(s):  
J. P. Colson ◽  
D. H. Reneker

Polyoxymethylene (POM) crystals grow inside trioxane crystals which have been irradiated and heated to a temperature slightly below their melting point. Figure 1 shows a low magnification electron micrograph of a group of such POM crystals. Detailed examination at higher magnification showed that three distinct types of POM crystals grew in a typical sample. The three types of POM crystals were distinguished by the direction that the polymer chain axis in each crystal made with respect to the threefold axis of the trioxane crystal. These polyoxymethylene crystals were described previously.At low magnifications the three types of polymer crystals appeared as slender rods. One type had a hexagonal cross section and the other two types had rectangular cross sections, that is, they were ribbonlike.


Author(s):  
A. Ourmazd ◽  
G.R. Booker ◽  
C.J. Humphreys

A (111) phosphorus-doped Si specimen, thinned to give a TEM foil of thickness ∼ 150nm, contained a dislocation network lying on the (111) plane. The dislocation lines were along the three <211> directions and their total Burgers vectors,ḇt, were of the type , each dislocation being of edge character. TEM examination under proper weak-beam conditions seemed initially to show the standard contrast behaviour for such dislocations, indicating some dislocation segments were undissociated (contrast A), while other segments were dissociated to give two Shockley partials separated by approximately 6nm (contrast B) . A more detailed examination, however, revealed that some segments exhibited a third and anomalous contrast behaviour (contrast C), interpreted here as being due to a new dissociation not previously reported. Experimental results obtained for a dislocation along [211] with for the six <220> type reflections using (g,5g) weak-beam conditions are summarised in the table below, together with the relevant values.


2020 ◽  
Vol 5 (2) ◽  
pp. 463-478
Author(s):  
Elizabeth Crais ◽  
Melody Harrison Savage

Purpose The shortage of doctor of philosophy (PhD)–level applicants to fill academic and research positions in communication sciences and disorders (CSD) programs calls for a detailed examination of current CSD PhD educational practices and the generation of creative solutions. The intended purposes of the article are to encourage CSD faculty to examine their own PhD program practices and consider the perspectives of recent CSD PhD graduates in determining the need for possible modifications. Method The article describes the results of a survey of 240 CSD PhD graduates and their perceptions of the challenges and facilitators to completing a PhD degree; the quality of their preparation in research, teaching, and job readiness; and ways to improve PhD education. Results Two primary themes emerged from the data highlighting the need for “matchmaking.” The first time point of needed matchmaking is prior to entry among students, mentors, and expectations as well as between aspects of the program that can lead to students' success and graduation. The second important matchmaking need is between the actual PhD preparation and the realities of the graduates' career expectations, and those placed on graduates by their employers. Conclusions Within both themes, graduate's perspectives and suggestions to help guide future doctoral preparation are highlighted. The graduates' recommendations could be used by CSD PhD program faculty to enhance the quality of their program and the likelihood of student success and completion. Supplemental Material https://doi.org/10.23641/asha.11991480


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