Many studies have sought to determine the origin and evolution of mitochondria. Although the Alphaproteobacteria are thought to be the closest relatives of the mitochondrial progenitor, there is dispute as to what its particular sister group is. Some have argued that mitochondria originated from ancestors of the order Rickettsiales, or more specifically of the Rickettsiaceae family, while others believe that ancestors of the family Rhodospirillaceae are also equally likely the progenitors. To resolve some of these disputes, sequence similarity searches and phylogenetic analyses were performed against mitochondria-related proteins in Saccharomyces cerevisiae. The 86 common matches of 5 Alphaproteobacteria (Rickettsia prowazekii, Rhodospirillum rubrum, Rhodopseudomonas palustris, Rhodobacter sphaeroides, and Ochrobactrum anthropi) to yeast mitochondrial proteins were distributed fairly evenly among the 5 species when sorted by highest identity or score. Moreover, exploratory phylogenetic analyses revealed that among these common matches, 44.19% (38) had branched most closely with O. anthropi, while only 34.88% (30) corresponded with Rickettsia prowazekii. More detailed phylogenetic analyses with additional Alphaproteobacteria and including genes from the mitochondria of Reclinomonas americana found matches of mitochondrial genes to those of members of the Rickettsiaceae, Anaplasmataceae, and Rhodospirillaceae families. The results support the idea that notable bacterial genome chimaerism has occurred en route to the formation of mitochondria.
Two predominant species of arsenic compounds, As(III) and As(V), are found in soils and natural water and they have been classified as carcinogens. The focus of the present study was to examine the speciation of Arsenic (As) across the water-sediment interface at the confluence of drainage for Gaya city and the Falgu River. Gas Chromatography (GC) coupled to Inductively Coupled Plasma Mass Spectrometry (ICP-MS) was used to analyze the organic arsenic species while the inorganic arsenic species, As(III) and As(V), were analyzed by Anion Exchange Chromatography (AEC) coupled with Inductively Coupled Plasma Mass Spectrometry (ICP-MS). The determination of total arsenic load was carried out by colorimetric method using silver diethyldithiocarbamate and was measured at 535 nm. Results revealed that the waters contained Monomethylarsine (MMA), Dimethylarsine (DMA), Trimethylarsine (TMA), As(III) as Arsenite (AsO3-3) and As(V) as Arsenate (AsO4-3). However, the methylated species were found in much higher concentrations in pore water from the sediment as compared to in the free water. The high levels of arsenic compounds found at the drainage sites pose a threat to human health and as such should be monitored and remediated promptly by the local and state governments
Mycobacterium is a genus of bacteria with over a hundred non-pathogenic and pathogenic species, best recognized for certain members known to cause diseases such as tuberculosis and leprosy. Two novel protein families important in the pathogenesis of Mycobacterium species are the PE and PPE families. These two protein families affect the antigenic profiles, disturbing host immunity. To better understand the origin and evolution of these gene families and the differences in their composition between pathogenic and non-pathogenic strains, several bioinformatic analyses were conducted both among Mycobacterium and closely related species that contain PE35 and PPE68 gene homologs. The methods included protein homology searches (BLASTP), horizontal gene transfer analysis (IslandViewer), phylogenetic analysis, gene cluster analysis and structural and functional constraints. Results revealed that PE and PPE gene homologs were not only limited to Mycobacterium, but also existed in three other non-mycobacterial genera, Rhodococcus, Tsukamurella and Segniliparus, and were possibly initially acquired from non-mycobacterial microorganisms by multiple horizontal gene transfers. Results also demonstrated that PE and PPE genes were more diverse and more rapidly evolving in pathogenic Mycobacterium as compared with non-pathogenic Mycobacterium and other non-mycobacterial species. These findings possibly shed light on the diverse functions and origins of the PE/PPE proteins among these organisms.
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