Creating novel specificities in a fungal nonself recognition system by single step homologous recombination events

SUMMARY Filamentous fungi spontaneously undergo vegetative cell fusion events within but also between individuals. These cell fusions (anastomoses) lead to cytoplasmic mixing and to the formation of vegetative heterokaryons (i.e., cells containing different nuclear types). The viability of these heterokaryons is genetically controlled by specific loci termed het loci (for heterokaryon incompatibility). Heterokaryotic cells formed between individuals of unlike het genotypes undergo a characteristic cell death reaction or else are severely inhibited in their growth. The biological significance of this phenomenon remains a puzzle. Heterokaryon incompatibility genes have been proposed to represent a vegetative self/nonself recognition system preventing heterokaryon formation between unlike individuals to limit horizontal transfer of cytoplasmic infectious elements. Molecular characterization of het genes and of genes participating in the incompatibility reaction has been achieved for two ascomycetes, Neurospora crassa and Podospora anserina. These analyses have shown that het genes are diverse in sequence and do not belong to a gene family and that at least some of them perform cellular functions in addition to their role in incompatibility. Divergence between the different allelic forms of a het gene is generally extensive, but single-amino-acid differences can be sufficient to trigger incompatibility. In some instances het gene evolution appears to be driven by positive selection, which suggests that the het genes indeed represent recognition systems. However, work on nonallelic incompatibility systems in P. anserina suggests that incompatibility might represent an accidental activation of a cellular system controlling adaptation to starvation.

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Seamless Personnel Authentication using Facial Recognition and Identity-Based Identification on Mobile Devices

International Journal of Recent Technology and Engineering - 2 ◽

10.35940/ijrte.c1009.1083s19 ◽

2019 ◽

Vol 8 (3S) ◽

pp. 41-46

Keyword(s):

Face Recognition ◽

Access Control ◽

Control Systems ◽

Mobile Devices ◽

Recognition System ◽

Single Step ◽

Biometric Data ◽

Face Recognition System ◽

The Face ◽

Identity Based

Security systems for buildings are no longer an uncommon thing in daily life with increasingly complex access control systems to achieve secured building security system. Achieving a hassle-free yet secure access control systems has been always a challenge for organizations especially for those managing large buildings. In this project, we develop a prototype that utilizes a combination of biometric and cryptography based security schemes to grant access control on personnel going in and out of a building. Our development achieves two-factor authentication in one single step which provides users a seamless experience for authentication. The identity-based identification (IBI) scheme that is based on number-theoretic cryptography is implemented on mobile devices to allow the identification scheme to run in the background. A face recognition system and web server is also developed which can be deployed on any PC at the market. The novelty lies in the combination of the two, with the face recognition making potential intruders difficult to forge biometric data of honest users, and the identity-based scheme preventing the adversary to learn any secrets from the authentication process, while allowing honest users to verify themselves from face to smartphone without any user intervention, thus creating a seamless authentication experience.

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A versatile bacterial expression vector designed for single-step cloning of multiple DNA fragments using homologous recombination

Protein Expression and Purification ◽

10.1016/j.pep.2014.03.002 ◽

2014 ◽

Vol 98 ◽

pp. 38-45 ◽

Cited By ~ 9

Author(s):

Mats A. Holmberg ◽

Naveen Kumar Chandappa Gowda ◽

Claes Andréasson

Keyword(s):

Homologous Recombination ◽

Expression Vector ◽

Single Step ◽

Bacterial Expression ◽

Dna Fragments

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A Natural Large Chromosomal Inversion inLactococcus lactis Is Mediated by Homologous Recombination between Two Insertion Sequences

Journal of Bacteriology ◽

10.1128/jb.180.18.4834-4842.1998 ◽

1998 ◽

Vol 180 (18) ◽

pp. 4834-4842 ◽

Cited By ~ 41

Author(s):

Marie-Line Daveran-Mingot ◽

Nathalie Campo ◽

Paul Ritzenthaler ◽

Pascal Le Bourgeois

Keyword(s):

Comparative Analysis ◽

Homologous Recombination ◽

Recombination Event ◽

Insertion Sequence ◽

Single Step ◽

Nucleotide Sequence Analysis ◽

Insertion Sequences ◽

Genetic Element ◽

Homologous Recombination Event ◽

Nucleotide Mutation

ABSTRACT Comparative analysis of chromosomal macrorestriction polymorphism of the two closely related Lactococcus lactis subsp.cremoris strains MG1363 and NCDO763 revealed the presence of a large inversion covering half of the genome. To determine what kind of genetic element could be implicated in this rearrangement, the two inversion junctions of MG1363 and NCDO763 chromosomes were cloned and characterized. Nucleotide sequence analysis showed the presence of one copy of the lactococcal IS905 element in each junction. Each copy of this element contained the same nucleotide mutation that inactivates the putative transposase. Comparison of the sequences surrounding the insertion sequence demonstrated that the large inversion arose from a single-step homologous recombination event between the two defective copies of the IS905 element. The large inversion presumably conferred no selective disadvantage on strain NCDO763 because this rearrangement did not alter theoriC-terC symmetry of the chromosome and the local genetic environment.

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Ascidian sperm receptor attached to the vitelline coat during oocyte maturation

Zygote ◽

10.1017/s0967199400130060 ◽

1999 ◽

Vol 8 (S1) ◽

pp. S14-S15 ◽

Cited By ~ 1

Author(s):

Hitoshi Sawada ◽

Etsuko Tanaka ◽

Yukichi Abe ◽

Satoshi Takizawa ◽

Youko Takahashi ◽

...

Keyword(s):

Oocyte Maturation ◽

Recognition System ◽

Molecular Entity ◽

Halocynthia Roretzi ◽

Sds Page ◽

Nonself Recognition ◽

Solitary Ascidian ◽

Protein Sequencer ◽

Main Component ◽

Vitelline Coat

While all ascidians (Urochordata) are hermaphroditic, some, including Halocynthia roretzi (Fuke, 1983) and Ciona intestinalis (Rosati & De Santis, 1978) are strictly self-sterile because of a self–nonself recognition system in the interaction between the sperm and the vitelline coat of the eggs. However, immature oocytes (Fuke & Numakunai, 1996) and acidic-seawater-treated mature oocytes (Morgan, 1939; Kawamura et al., 1991) are self-fertile. It is thought that a putative self–nonself recognition molecule, which is detached or modified by treatment with acidic seawater, may be attached to the vitelline coat during oocyte maturation. Although the existence of a self–nonself recognition system in the fertilisation process is well known, the molecular entity has yet to be conclusively identified. However, there have been several attempts to identify such a molecule in Ciona (Marino et al., 1999). In the present study, we have isolated and analysed a molecule which appears to be responsible for allorecognition in the interaction between sperm and eggs of the ascidian Halocynthia roretzi.Biologicals. A solitary ascidian Halocynthia roretzi Type C was used in this study. The fertilisation experiment was carried out as described previously (Sawada et al., 1982).Isolation and N-terminal Sequencing of Hr VC70. Vitelline coats were isolated from immature and mature oocytes of the ascidian by homogenisation and repeated washing with 5× diluted artificial seawater. The isolated vitelline coats were subjected to SDS-PAGE, followed by blotting to a PVDF membrane. The N-terminal amino acid sequence of the 70 kDa main component (HrVC70) was determined by a protein sequencer.

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Restoration of Gene Function by Homologous Recombination: from PCR to Gene Expression in One Step

Applied and Environmental Microbiology ◽

10.1128/aem.70.12.7156-7160.2004 ◽

2004 ◽

Vol 70 (12) ◽

pp. 7156-7160 ◽

Cited By ~ 4

Author(s):

Ido Yosef ◽

Noga Bloushtain ◽

Michal Shapira ◽

Udi Qimron

Keyword(s):

Homologous Recombination ◽

Single Step ◽

Selection Marker ◽

Drug Selection ◽

Promoter Regions ◽

Simple Method ◽

Pcr Product ◽

One Step ◽

Dna Fragment ◽

Λ Red

ABSTRACT We have developed a simple method for single-step cloning of any PCR product into a plasmid. A novel selection principle has been applied, in which activation of a drug selection marker is achieved following homologous recombination. In this method a DNA fragment is amplified by PCR with standard oligonucleotides that contain flanking tails derived from the host plasmid and the complete λPR or rrnA1 promoter regions. The resulting PCR product is then electroporated into an Escherichia coli strain harboring both the phage λ Red functions and the host plasmid. Upon homologous recombination of the PCR fragment into the plasmid, expression of a drug selection marker is fully induced due to restoration of its truncated promoter, thus allowing appropriate selection. Recombinant plasmid vectors encoding β-galactosidase and neomycin phosphotransferase were constructed by using this method in two well-known Red systems. This cloning strategy significantly reduces both the time and costs associated with cloning procedures.

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