scholarly journals Extremely reduced supergroup F Wolbachia: transition to obligate insect symbionts

2021 ◽  
Author(s):  
Sazzad Mahmood ◽  
Eva Novakova ◽  
Jana Martinu ◽  
Oldrich Sychra ◽  
Vaclav Hypsa
Keyword(s):  
Genome Size ◽  
Broad Spectrum ◽  
Genomic Data ◽  
The Other ◽  
Symbiotic Bacteria ◽  
Evolutionary Trajectory ◽  
Evolutionary Transitions ◽  
Chewing Lice ◽  
Reduced Genome ◽  
Insect Symbionts

Wolbachia are widely distributed symbionts among invertebrates that manifest by a broad spectrum of lifestyles from parasitism to mutualism. Wolbachia Supergroup F is considered a particularly interesting group which gave rise to symbionts of both arthropods and nematodes, and some of its members are obligate mutualists. Further investigations on evolutionary transitions in symbiosis have been hampered by a lack of genomic data for Supergroup F members. In this study, we present genomic data for five new supergroup F Wolbachia strains associated with four chewing lice species. These new strains in different evolutionary stages show genomic characteristics well-illustrating the evolutionary trajectory which symbiotic bacteria experience during their transition to mutualism. Three of the strains have not yet progressed with the transition, the other two show typical signs of ongoing gene deactivation and removal (genome size, coding density, low number of pseudogenes). Particularly, wMeur1, a symbiont fixed in all Menacanthus eurystenus populations across four continents, possesses a highly reduced genome of 733,850 bp with a horizontally acquired capacity for pantothenate synthesis. Comparing with other strains showed wMeur1 genome as the smallest currently known among all Wolbachia and the first example of Wolbachia which has completed genomic streamlining known from the gammaproteobacterial obligate symbionts.

Maternally inherited symbiotic bacteria in ticks: incidence and biological importance

2019 ◽  
Vol 24 (1) ◽  
pp. 158 ◽  
Author(s):  
Yan Kai Zhang ◽  
Jing Ze Liu
Keyword(s):  
Pathogenic Bacteria ◽  
Food Source ◽  
Genomic Data ◽  
Blood Feeding ◽  
Symbiotic Bacteria ◽  
Evolutionary Transitions ◽  
Biological Importance ◽  
Geographical Populations ◽  
Veterinary Importance ◽  
New Strategies

Ticks are exclusive blood-feeding parasites that are of medical and veterinary importance. Ticks are also host for several maternally inherited symbiotic bacteria that are non-pathogenic bacteria and have potential roles in tick biology and the transmission of co-infecting pathogens. In order to gain a comprehensive view of these symbionts in ticks, we overviewed their incidence and biological importance within ticks based on available data. The symbionts in ticks are diverse, and their incidence and frequency vary across different tick species and different geographical populations of the same species. In some cases, symbionts of Coxiella, Francisella and Rickettsia genera may provide tick hosts essential nutrients absent from the exclusive food source of ticks and exhibit mutualistic relationships with their hosts. However, most symbionts are facultative and affect the biological phenotypes of their tick hosts through various ways. For some strains of Coxiella and Francisella, advanced genomic data and phylogenetic investigations have revealed their interactions with hosts and their evolutionary transitions of pathogenic and mutualistic forms. These findings are valuable for understanding tick-symbiont associations, and may help to develop new strategies to control ticks and tick-borne diseases.

scholarly journals Inducible Macrolide Resistance inCorynebacterium jeikeium

2001 ◽  
Vol 45 (7) ◽  
pp. 1982-1989 ◽  
Author(s):  
Adriana E. Rosato ◽  
Bonnie S. Lee ◽  
Kevin A. Nash
Keyword(s):  
Drug Resistance ◽  
Resistance Genes ◽  
Broad Spectrum ◽  
Antimicrobial Agents ◽  
Opportunistic Pathogen ◽  
Macrolide Resistance ◽  
The Other ◽  
Broad Spectrum Resistance ◽  
Neutropenic Patients ◽  
Group 3

ABSTRACT Corynebacterium jeikeium is an opportunistic pathogen primarily of immunocompromised (neutropenic) patients. Broad-spectrum resistance to antimicrobial agents is a common feature of C. jeikeium clinical isolates. We studied the profiles of susceptibility of 20 clinical strains of C. jeikeium to a range of antimicrobial agents. The strains were separated into two groups depending on the susceptibility to erythromycin (ERY), with one group (17 strains) representing resistant organisms (MIC > 128 μg/ml) and the second group (3 strains) representing susceptible organisms (MIC ≤ 0.25 μg/ml). The ERY resistance crossed to other members of the macrolide-lincosamide-streptogramin B (MLSb) group. Furthermore, this resistance was inducible with MLSb agents but not non-MLSb agents. Expression of ERY resistance was linked to the presence of an allele of the class X erm genes,erm(X)cj, with >93% identity to other ermgenes of this class. Our evidence indicates that erm(X)cj is integrated within the chromosome, which contrasts with previous reports for the plasmid-associated erm(X) genes found inC. diphtheriae and C. xerosis. In 40% ofC. jeikeium strains, erm(X)cj is present within the transposon, Tn5432. However, in the remaining strains, the components of Tn5432 (i.e., the erm and transposase genes) have separated within the chromosome. The rearrangement of Tn5432 leads to the possibility that the other drug resistance genes have become included in a new composite transposon bound by the IS1249 elements.

scholarly journals Acquisition and metabolism of carbon in the Ochrophyta other than diatoms

2017 ◽  
Vol 372 (1728) ◽  
pp. 20160400 ◽  
Author(s):  
John A. Raven ◽  
Mario Giordano
Keyword(s):  
Carbon Metabolism ◽  
Brown Algae ◽  
C4 Photosynthesis ◽  
Genomic Data ◽  
Diagnostic Value ◽  
The Other ◽  
High K ◽  
C4 Metabolism ◽  
Low Amplitude ◽  
C3 Metabolism

The acquisition and assimilation of inorganic C have been investigated in several of the 15 clades of the Ochrophyta other than diatoms, with biochemical, physiological and genomic data indicating significant mechanistic variation. Form ID Rubiscos in the Ochrophyta are characterized by a broad range of kinetics values. In spite of relatively high K 0.5 CO 2 and low CO 2 : O 2 selectivity, diffusive entry of CO 2 occurs in the Chrysophyceae and Synurophyceae. Eustigmatophyceae and Phaeophyceae, on the contrary, have CO 2 concentrating mechanisms, usually involving the direct or indirect use of . This variability is possibly due to the ecological contexts of the organism. In brown algae, C fixation generally takes place through a classical C3 metabolism, but there are some hints of the occurrence of C4 metabolism and low amplitude CAM in a few members of the Fucales. Genomic data show the presence of a number of potential C4 and CAM genes in Ochrophyta other than diatoms, but the other core functions of many of these genes give a very limited diagnostic value to their presence and are insufficient to conclude that C4 photosynthesis is present in these algae. This article is part of the themed issue ‘The peculiar carbon metabolism in diatoms'.

scholarly journals GENOME SIZE IN THREE SPECIES OF Glandularia AND THEIR HYBRIDS

2019 ◽  
Vol 30 (2) ◽  
pp. 47-54
Author(s):  
M.R. Ferrari ◽  
E.J. Greizerstein ◽  
L. Poggio
Keyword(s):  
Genome Size ◽  
Dna Content ◽  
High Frequency ◽  
Parental Species ◽  
The Other ◽  
F1 Hybrids ◽  
Homoeologous Pairing ◽  
The Relationship ◽  
Species Being ◽  
Homoeologous Chromosomes

In this work the relationship between genome size of Glandularia species and the meiotic configurations found in their hybrids are discussed. Glandularia incisa (Hook.) Tronc., growing in two localities of Corrientes and Córdoba provinces, Argentina, with different ecological conditions, showed inter-population variability of the 2C-value. The DNA content found in the Corrientes locality (2.41 pg) was higher than that obtained in the Córdoba locality (2.09 pg) which has more stressful environmental conditions than the former. These values are statistically different from those that were found in Glandularia pulchella (Sweet) Tronc. from Corrientes (1.43 pg) and in Glandularia perakii Cov. et Schn from Córdoba (1.47 pg). The DNA content of the diploid F1 hybrids, G. pulchella × G. incisa and G. perakii × G. incisa, differed statistically from the DNA content of the parental species, being intermediate between them. Differences in the frequency of pairing of homoeologous chromosomes were observed in the hybrids; these differences cannot be explained by differences in genome size since hybrids with similar DNA content differ significantly in their meiotic behavior. On the other hand, the differences in the DNA content between the parental species justify the presence of a high frequency of heteromorphic open and closed bivalents and univalents with different size in the hybrids. Key words: Intra-specific DNA content variability, homoeologous pairing, heteromorphic bivalents

Entrepreneurship Policy Framework

2017 ◽  
pp. 95-139
Author(s):  
Raghubir Singh Chauhan ◽  
Rituparna Das
Keyword(s):  
Literature Review ◽  
Broad Spectrum ◽  
The Other ◽  
Policy Framework ◽  
Entrepreneurship Policy ◽  
Ongoing Debate ◽  
Space And Time ◽  
Multi Stage ◽  
Economic Understanding

The ongoing debate regarding how to formulate an entrepreneurship policy is globally vital so it is pertinent to understand the other dimensions also. By using a broad spectrum of space and time, and covering heterogeneous correlation the why, what if, where etc. regarding policy framework and deeper fundamentals of global economic understanding as well as misunderstanding is explored on an intersubjective context. By multi-stage data substantiation, analysis and literature review the direction and important determinants of policy framework are examined.

scholarly journals Flying High—Muscle-Specific Underreplication in Drosophila

Genes ◽  
2020 ◽  
Vol 11 (3) ◽  
pp. 246 ◽  
Author(s):  
J. Spencer Johnston ◽  
Mary E. Zapalac ◽  
Carl E. Hjelmen
Keyword(s):  
Flow Cytometry ◽  
Dna Synthesis ◽  
Salivary Glands ◽  
Genome Size ◽  
Flight Muscle ◽  
S Phase ◽  
The Other ◽  
Tissue Type ◽  
Flight Muscles ◽  
Longitudinal Muscles

Drosophila underreplicate the DNA of thoracic nuclei, stalling during S phase at a point that is proportional to the total genome size in each species. In polytene tissues, such as the Drosophila salivary glands, all of the nuclei initiate multiple rounds of DNA synthesis and underreplicate. Yet, only half of the nuclei isolated from the thorax stall; the other half do not initiate S phase. Our question was, why half? To address this question, we use flow cytometry to compare underreplication phenotypes between thoracic tissues. When individual thoracic tissues are dissected and the proportion of stalled DNA synthesis is scored in each tissue type, we find that underreplication occurs in the indirect flight muscle, with the majority of underreplicated nuclei in the dorsal longitudinal muscles (DLM). Half of the DNA in the DLM nuclei stall at S phase between the unreplicated G0 and fully replicated G1. The dorsal ventral flight muscle provides the other source of underreplication, and yet, there, the replication stall point is earlier (less DNA replicated), and the endocycle is initiated. The differences in underreplication and ploidy in the indirect flight muscles provide a new tool to study heterochromatin, underreplication and endocycle control.

scholarly journals Fidelity in Archaeal Information Processing

Archaea ◽  
2010 ◽  
Vol 2010 ◽  
pp. 1-15 ◽  
Author(s):  
Bart de Koning ◽  
Fabian Blombach ◽  
Stan J. J. Brouns ◽  
John van der Oost
Keyword(s):  
Gene Expression ◽  
Quality Control ◽  
Information Processing ◽  
Genome Size ◽  
Genetic Information ◽  
Important Determinant ◽  
Current Knowledge ◽  
The Other ◽  
Living Systems ◽  
Evolution Of Life

A key element during the flow of genetic information in living systems is fidelity. The accuracy of DNA replication influences the genome size as well as the rate of genome evolution. The large amount of energy invested in gene expression implies that fidelity plays a major role in fitness. On the other hand, an increase in fidelity generally coincides with a decrease in velocity. Hence, an important determinant of the evolution of life has been the establishment of a delicate balance between fidelity and variability. This paper reviews the current knowledge on quality control in archaeal information processing. While the majority of these processes are homologous in Archaea, Bacteria, and Eukaryotes, examples are provided of nonorthologous factors and processes operating in the archaeal domain. In some instances, evidence for the existence of certain fidelity mechanisms has been provided, but the factors involved still remain to be identified.

Genome size ofPachypsylla venusta(Hemiptera: Psyllidae) and the ploidy of its bacteriocyte, the symbiotic host cell that harbors intracellular mutualistic bacteria with the smallest cellular genome

2009 ◽  
Vol 100 (1) ◽  
pp. 27-33 ◽  
Author(s):  
A. Nakabachi ◽  
S. Koshikawa ◽  
T. Miura ◽  
S. Miyagishima
Keyword(s):  
Image Analysis ◽  
Genome Size ◽  
Genome Analysis ◽  
Symbiotic Bacteria ◽  
Symbiotic Relationship ◽  
Whole Genome ◽  
Whole Genome Analysis ◽  
Genetic Mechanisms ◽  
Haploid Genome Size ◽  
Cellular Genome

AbstractPsyllids harbor the primary symbiont,Carsonella ruddii(γ-Proteobacteria), within the cytoplasm of specialized cells called bacteriocytes.Carsonellahas the smallest known cellular genome (160 kb), lacking numerous genes that appear to be essential for bacterial life. This raises the question regarding the genetic mechanisms of the host which supports the survival ofCarsonella. Our preceding analyses have indicated that some of the genes that are encoded in the psyllid genome and which are highly expressed in the bacteriocyte are of bacterial origin. This implies that psyllids acquired genes from bacteria by lateral gene transfer (LGT) and are using these genes to maintain the primary symbiont,Carsonella. To reveal the complete picture of LGT from symbiotic bacteria to the genome of psyllids, whole genome analysis of psyllids is essential. In order to assess the feasibility of whole genome analysis of the host psyllid, the genome size of the hackberry petiole gall psyllid,Pachypsylla venusta, was estimated. Feulgen image analysis densitometry and flow cytometry demonstrated that the haploid genome size ofP. venustais 0.74 pg (724 Mb), verifying the feasibility of whole genome analysis. Feulgen image analysis densitometry further revealed that bacteriocytes ofP. venustaare invariably 16-ploid. This higher ploidy may be essential to facilitate the symbiotic relationship with bacteria, as it appears to be a feature common to insect bacteriocytes. These results provide a foundation for genomics-based research into host-symbiont interactions.

scholarly journals Interaction of selection and recombination in the fixation of negative-epistatic genes

1996 ◽  
Vol 67 (3) ◽  
pp. 257-269 ◽  
Author(s):  
Yannis Michalakis ◽  
Montgomery Slatkin
Keyword(s):  
Double Mutant ◽  
Static Model ◽  
The Other ◽  
Relative Importance ◽  
Selection Intensity ◽  
Recombination Rates ◽  
Epistatic Interactions ◽  
Evolutionary Transitions ◽  
Negative Epistasis ◽  
Probability Of Fixation

SummaryWe investigated the interaction of recombination and selection on the process of fixation of two linked loci with epistatic interactions in fitness. We consider both the probability of fixation of newly arising mutants (the static model) and the time to fixation under continued mutation (the dynamic model). Our results show that the fixation of a new advantageous combination is facilitated by higher fitness of the advantageous genotype and by weaker selection against the intermediate deleterious genotypes. Fixation occurs more rapidly when the recombination rates are small, except when selection against intermediate genotypes is weak and selection in favour of the double mutant is very strong. In these cases fixation is more rapid when the recombinant rate is large. Mutations of strong effects, deleterious when alone but beneficial when coupled, are fixed more easily than mutations of intermediate effects, at least for large recombination rates. Among the possible pathways the process of fixation might follow, independent substitutions lead to the fixation of the double mutant only when selection is weak. The relative importance of the other pathways depends on the interaction between recombination and selection. The coupled-gamete pathway (i.e. when the population waits until the double mutant appears and then drives it to fixation) is more important as selection intensity increases and the recombination rate is reduced. For all recombination rates, asymmetries in fitness of the intermediate genotypes increase the rate at which fixations occur. Finally, throughout the fixation process, the population will be monomorphic at least at one of the two loci for most of the time, which implies that there would be little opportunity to detect the presence of negative epistasis even if it were important for occasional evolutionary transitions.

scholarly journals Mutational Replacement of Leu-293 in the Class C Enterobacter cloacae P99 β-Lactamase Confers Increased MIC of Cefepime

2002 ◽  
Vol 46 (6) ◽  
pp. 1966-1970 ◽  
Author(s):  
Sergei B. Vakulenko ◽  
Dasantila Golemi ◽  
Bruce Geryk ◽  
Maxim Suvorov ◽  
James R. Knox ◽  
...  
Keyword(s):  
Kinetic Parameters ◽  
Broad Spectrum ◽  
Random Mutagenesis ◽  
Enterobacter Cloacae ◽  
The Other ◽  
Mutant Enzyme ◽  
Wild Type ◽  
Wild Type Enzyme ◽  
Wide Range ◽  
Class C

ABSTRACT The class C β-lactamase from Enterobacter cloacae P99 confers resistance to a wide range of broad-spectrum β-lactams but not to the newer cephalosporin cefepime. Using PCR mutagenesis of the E. cloacae P99 ampC gene, we obtained a Leu-293-Pro mutant of the P99 β-lactamase conferring a higher MIC of cefepime (MIC, 8 μg/ml, compared with 0.5 μg/ml conferred by the wild-type enzyme). In addition, the mutant enzyme produced higher resistance to ceftazidime but not to the other β-lactams tested. Mutants with 15 other replacements of Leu-293 were prepared by site-directed random mutagenesis. None of these mutant enzymes conferred MICs of cefepime higher than that conferred by Leu-293-Pro. We determined the kinetic parameters of the purified E. cloacae P99 β-lactamase and the Leu-293-Pro mutant enzyme. The catalytic efficiencies (k cat/Km ) of the Leu-293-Pro mutant β-lactamase for cefepime and ceftazidime were increased relative to the respective catalytic efficiencies of the wild-type P99 β-lactamase. These differences likely contribute to the higher MICs of cefepime and ceftazidime conferred by this mutant β-lactamase.

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