Clarifying the Unique Features of Bacterial Sex

2021 ◽  
pp. 60-71
Author(s):  
Thomas E. Schindler
Keyword(s):  
Sexual Reproduction ◽  
Genetic Recombination ◽  
Entire Genome ◽  
Genetic Transfer ◽  
Time Points

This chapter considers bacterial sex, the details of which turned out to be counter-intuitive, quite different from Joshua Lederberg’s conceptions that were influenced by the ways that higher organisms recombined genes. The contributions of Luca Cavalli, William Hayes, and later, Elie Wollman and Francoise Jacob served to clarify the apparent anomalies, finally to reveal that bacterial sex was very, very different from the modes of genetic recombination of other organisms. The French team clarified the stages of conjugation by interrupting the mating of Hfr x F- at different time points. HGT, can occur by three different processes: transformation, conjugation, and transduction. In every case, HGT is fragmentary and unidirectional, much different than genetic transfer in sexual reproduction in higher organisms, which involves the entire genome in a mutual, two-way recombination of genes.

Strange Genetics

2021 ◽  
pp. 52-59
Author(s):  
Thomas E. Schindler
Keyword(s):  
Sexual Reproduction ◽  
Genetic Recombination ◽  
Bacterial Host ◽  
Genetic Transfer ◽  
Genetic Traits ◽  
F Factor ◽  
Transfer Genes ◽  
Dissertation Research ◽  
At Will ◽  
Joshua Lederberg

This chapter relates how, in the 1950s, Esther and Joshua Lederberg and their colleagues uncovered a whole new kind of genetic transfer involving plasmids and viruses. In plants and animals, genetic recombination is integrated within the processes of sexual reproduction. Imagine if you could trade genes with strangers at will! That’s what bacteria can do. Esther Lederberg’s discoveries of the F-plasmid and the λ‎ bacteriophage were happy accidents that occurred while she working to complete her dissertation research. Serendipity happens to those who are very attentive, broadly experienced, and open to surprises. Esther Lederberg discovered a transferable factor, the F-factor, that could transform recipients into donors. Then she discovered a lysogenic virus, hiding harmlessly inside the chromosome of its bacterial host. These two surprising discoveries showed that bacteria could transfer genes and pieces of chromosomes horizontally, as opposed to the classical inheritance of plants and animals which pass on genetic traits vertically, down through generations.

scholarly journals Microsatellite and Chromosome Evolution of Parthenogenetic Sitobion Aphids in Australia

Genetics ◽  
1996 ◽  
Vol 144 (2) ◽  
pp. 747-756 ◽  
Author(s):  
Paul Sunnucks ◽  
Phillip R England ◽  
Andrea C Taylor ◽  
Dinah F Hales
Keyword(s):  
Sexual Reproduction ◽  
Chromosome Evolution ◽  
Genetic Recombination ◽  
Allelic Variation ◽  
Repeat Unit ◽  
Chromosomal Evolution ◽  
Microsatellite Variation ◽  
Wide Range ◽  
Sexual Recombination ◽  
Minimum Numbers

Abstract Single-locus microsatellite variation correlated perfectly with chromosome number in Sitobion miscanthi aphids. The microsatellites were highly heterozygous, with up to 10 alleles per locus in this species. Despite this considerable allelic variation, only seven different S. miscanthi genotypes were discovered in 555 individuals collected from a wide range of locations, hosts and sampling periods. Relatedness between genotypes suggests only two successful colonizations of Australia. There was no evidence for genetic recombination in 555 S. miscanthi so the occurrence of recent sexual reproduction must be near zero. Thus diversification is by mutation and chromosomal rearrangement alone. Since the aphids showed no sexual recombination, microsatellites can mutate without meiosis. Five of seven microsatellite differences were a single repeat unit, and one larger jump is likely. The minimum numbers of changes between karyotypes corresponded roughly one-to-one with microsatellite allele changes, which suggests very rapid chromosomal evolution. A chromosomal fission occurred in a cultured line, and a previously unknown chromosomal race was detected. All 121 diverse S. near fragariae were heterozygous but revealed only one genotype. This species too must have a low rate of sexual reproduction and few colonizations of Australia.

scholarly journals Fungal clones win the battle, but recombination wins the war

IMA Fungus ◽  
2019 ◽  
Vol 10 (1) ◽  
Author(s):  
André Drenth ◽  
Alistair R. McTaggart ◽  
Brenda D. Wingfield
Keyword(s):  
Sexual Reproduction ◽  
Fungal Pathogen ◽  
Genetic Recombination ◽  
Genetic Material ◽  
Clonal Reproduction ◽  
Changing Environment ◽  
Space And Time ◽  
Pathogen Populations

Abstract Clonal reproduction is common in fungi and fungal-like organisms during epidemics and invasion events. The success of clonal fungi shaped systems for their classification and some pathogens are tacitly treated as asexual. We argue that genetic recombination driven by sexual reproduction must be a starting hypothesis when dealing with fungi for two reasons: (1) Clones eventually crash because they lack adaptability; and (2) fungi find a way to exchange genetic material through recombination, whether sexual, parasexual, or hybridisation. Successful clones may prevail over space and time, but they are the product of recombination and the next successful clone will inevitably appear. Fungal pathogen populations are dynamic rather than static, and they need genetic recombination to adapt to a changing environment.

scholarly journals Identification of Eighteen Berberis Species as Alternate Hosts of Puccinia striiformis f. sp. tritici and Virulence Variation in the Pathogen Isolates from Natural Infection of Barberry Plants in China

2013 ◽  
Vol 103 (9) ◽  
pp. 927-934 ◽  
Author(s):  
Jie Zhao ◽  
Long Wang ◽  
Zhiyan Wang ◽  
Xianming Chen ◽  
Hongchang Zhang ◽  
...  
Keyword(s):  
Sexual Reproduction ◽  
Stripe Rust ◽  
Puccinia Striiformis ◽  
Genetic Recombination ◽  
Natural Infection ◽  
Rust Fungi ◽  
Sexual Cycle ◽  
Natural Conditions ◽  
Rust Pathogen ◽  
Its Regions

The wheat stripe rust pathogen (Puccinia striiformis f. sp. tritici) population in China has been reported to be a distinct genetic group with higher diversity than those in many other countries. Genetic recombination in the P. striiformis f. sp. tritici population has been identified with molecular markers but whether sexual reproduction occurs in China is unknown. In this study, we surveyed barberry plants for infection by rust fungi in the stripe rust “hotspot” regions in Gansu, Sichuan, and Shaanxi provinces; collected barberry plants and inoculated plants of 20 Berberis spp. with germinated teliospores under controlled greenhouse conditions for susceptibility to P. striiformis f. sp. tritici; and tested P. striiformis f. sp. tritici isolates obtained from aecia on naturally infected barberry plants on the wheat genotypes used to differentiate Chinese P. striiformis f. sp. tritici races to determine virulence variations. Different Berberis spp. were widely distributed and most surveyed plants had pycnia and aecia of rust fungi throughout the surveyed regions. In total, 28 Berberis spp. were identified during our study. From 20 Berberis spp. tested with teliospores of P. striiformis f. sp. tritici from wheat plants, 18 species were susceptible under greenhouse conditions. Among 3,703 aecia sampled from barberry plants of three species (Berberis shensiana, B. brachypoda, and B. soulieana) under natural infections in Gansu and Shaanxi provinces, four produced P. striiformis f. sp. tritici uredinia on susceptible wheat ‘Mingxian 169’. Sequence of the internal transcribed spacer (ITS) regions of the four isolates from barberry shared 99% identity with the P. striiformis f. sp. tritici sequences in the National Center for Biotechnology Information database. The four isolates had virulence patterns different from all previously reported races collected from wheat plants. Furthermore, 82 single-uredinium isolates obtained from the four barberry isolates had high virulence diversity rates of 9.0 to 28.1%, indicating that the diverse isolates were produced through sexual reproduction on barberry plants under natural conditions. In addition to P. striiformis f. sp. tritici, sequence analysis of polymerase chain reaction products of the ITS regions and inoculation tests on wheat identified P. graminis (the stem rust pathogen). Our results indicated that P. striiformis f. sp. tritici can infect some Berberis spp. under natural conditions, and the sexual cycle of the fungus may contribute to the diversity of P. striiformis f. sp. tritici in China.

scholarly journals Identification of the Mating-Type (MAT) Locus That Controls Sexual Reproduction of Blastomyces dermatitidis

2012 ◽  
Vol 12 (1) ◽  
pp. 109-117 ◽  
Author(s):  
Wenjun Li ◽  
Thomas D. Sullivan ◽  
Eric Walton ◽  
Anna Floyd Averette ◽  
Sharadha Sakthikumar ◽  
...  
Keyword(s):  
Sexual Reproduction ◽  
Mating Type ◽  
Genetic Recombination ◽  
Sexual Cycle ◽  
Blastomyces Dermatitidis ◽  
Comparative Genomic ◽  
Dimorphic Fungi ◽  
Content Type ◽  
Long Time ◽  
Northern United States

ABSTRACTBlastomyces dermatitidisis a dimorphic fungal pathogen that primarily causes blastomycosis in the midwestern and northern United States and Canada. While the genes controlling sexual development have been known for a long time, the genes controlling sexual reproduction ofB. dermatitidis(teleomorph,Ajellomyces dermatitidis) are unknown. We identified the mating-type (MAT) locus in theB. dermatitidisgenome by comparative genomic approaches. TheB. dermatitidis MATlocus resembles those of other dimorphic fungi, containing either an alpha-box (MAT1-1) or an HMG domain (MAT1-2) gene linked to theAPN2,SLA2, andCOX13genes. However, in some strains ofB. dermatitidis, theMATlocus harbors transposable elements (TEs) that make it unusually large compared to theMATlocus of other dimorphic fungi. Based on theMATlocus sequences ofB. dermatitidis, we designed specific primers for PCR determination of the mating type. TwoB. dermatitidisisolates of opposite mating types were cocultured on mating medium. Immature sexual structures were observed starting at 3 weeks of coculture, with coiled-hyphae-containing cleistothecia developing over the next 3 to 6 weeks. Genetic recombination was detected in potential progeny by mating-type determination, PCR-restriction fragment length polymorphism (PCR-RFLP), and random amplification of polymorphic DNA (RAPD) analyses, suggesting that a meiotic sexual cycle might have been completed. The F1 progeny were sexually fertile when tested with strains of the opposite mating type. Our studies provide a model for the evolution of theMATlocus in the dimorphic and closely related fungi and open the door to classic genetic analysis and studies on the possible roles of mating and mating type in infection and virulence.

scholarly journals On the enigmatic origin of the Mediterranean invasive Caulerpa racemosa (Caulerpales, Chlorophyta)

2006 ◽  
Vol 7 (1) ◽  
pp. 119 ◽  
Author(s):  
P. PANAYOTIDIS
Keyword(s):  
Invasive Species ◽  
Sexual Reproduction ◽  
20Th Century ◽  
Genetic Recombination ◽  
Rapid Expansion ◽  
Caulerpa Racemosa ◽  
The Mediterranean

The successful sexual reproduction of the Mediterranean invasive species Caulerpa racemosa could explain not only its rapid expansion during the last decade of the 20th century, but also its origin, through hybridation and genetic recombination of preexisting varieties. This paper argues on the cryptogenic origin of the Mediterranean invasive Caulerpa racemosa.

scholarly journals Genetic diversity in facultatively sexual populations and its implications for the origins of self-incompatibility in algae and fungi

2021 ◽  
Author(s):  
Aaron S.A. Smith ◽  
Sarah Penington ◽  
Ian Letter ◽  
Daniel B Wilson ◽  
George W. A. Constable
Keyword(s):  
Sexual Reproduction ◽  
Genetic Recombination ◽  
Competitive Dynamics ◽  
Small Populations ◽  
Mating Types ◽  
Self Incompatibility ◽  
Type Classes ◽  
Distinct Individual ◽  
Competing Hypotheses ◽  
Reproductive Events

The evolutionary mechanism that drove the establishment of self-incompatibility in early sexual eukaryotes is still a debated topic. While a number of competing hypotheses have been proposed, many have not received detailed theoretical attention. In particular, the hypothesis that self-incompatibility increases the benefits of genetic recombination in sexual haploids has been comparatively understudied. In this paper we address this topic by mathematically deriving how the probability of mating with a genetically distinct individual changes as a function of the presence or absence of self-incompatible mating type classes. We find that although populations with mating types successfully engage in sexual reproduction less frequently than their self-compatible competitors, they can nevertheless engage in useful sex with genetically distinct partners \emph{more} frequently. This conclusion holds when the number of sexual reproductive events per generation is low (i.e. in small populations with low rates of facultative sexual reproduction). Finally we demonstrate the potential for frequency-dependent selection in competitive dynamics between self-compatible and self-incompatible types. These analytic results provide a baseline for studying the sex advantage enhancer model for the evolutionary origin of mating types within each specific hypothesis for the evolution of recombination.

scholarly journals Genetic Recombination without Sexual Reproduction in Aspergillus niger

1953 ◽  
Vol 8 (1) ◽  
pp. 198-210 ◽  
Author(s):  
G. Pontecorvo ◽  
J. A. Roper ◽  
E. Forbes
Keyword(s):  
Aspergillus Niger ◽  
Sexual Reproduction ◽  
Genetic Recombination

Elimination of altered karyotypes by sexual reproduction preserves species identity

Genome ◽  
2007 ◽  
Vol 50 (5) ◽  
pp. 517-524 ◽  
Author(s):  
Henry H.Q. Heng
Keyword(s):  
Genetic Diversity ◽  
Sexual Reproduction ◽  
Cancer Cells ◽  
Evolutionary Biology ◽  
Genetic Recombination ◽  
Deleterious Mutations ◽  
Species Identity ◽  
Sexual Process ◽  
Controlled Reproduction ◽  
Chromosome Level

Resolving the persistence of sexual reproduction despite its overwhelming costs (known as the paradox of sex) is one of the most persistent challenges of evolutionary biology. In thinking about this paradox, the focus has traditionally been on the evolutionary benefits of genetic recombination in generating offspring diversity and purging deleterious mutations. The similarity of pattern between evolution of organisms and evolution among cancer cells suggests that the asexual process generates more diverse genomes owing to less controlled reproduction systems, while sexual reproduction generates more stable genomes because the sexual process can serve as a mechanism to “filter out” aberrations at the chromosome level. Our reinterpretation of data from the literature strongly supports this hypothesis. Thus, the principal consequence of sexual reproduction is the reduction of drastic genetic diversity at the genome or chromosome level, resulting in the preservation of species identity rather than the provision of evolutionary diversity for future environmental challenges. Genetic recombination does contribute to genetic diversity, but it does so secondarily and within the framework of the chromosomally defined genome.

scholarly journals Spindle Dynamics during Meiotic Development of the Fungus Podospora anserina Requires the Endoplasmic Reticulum-Shaping Protein RTN1

mBio ◽  
2021 ◽  
Author(s):  
Antonio de Jesús López-Fuentes ◽  
Karime Naid Nachón-Garduño ◽  
Fernando Suaste-Olmos ◽  
Ariadna Mendieta-Romero ◽  
Leonardo Peraza-Reyes
Keyword(s):  
Endoplasmic Reticulum ◽  
Genetic Variation ◽  
Cell Division ◽  
Sexual Reproduction ◽  
Genetic Recombination ◽  
Podospora Anserina ◽  
Eukaryotic Evolution ◽  
Spindle Dynamics

Meiosis consists of a reductional cell division, which allows ploidy maintenance during sexual reproduction and which provides the potential for genetic recombination, producing genetic variation. Meiosis constitutes a process of foremost importance for eukaryotic evolution.

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