Direct imaging of RecA nucleation and growth on single molecules of SSB-coated ssDNA.

Escherichia coli RecA is the defining member of a ubiquitous class of DNA strand-exchange proteins that are essential for homologous recombination, a pathway that maintains genomic integrity by repairing broken DNA. To function, filaments of RecA must nucleate and grow on single-stranded DNA (ssDNA) in direct competition with ssDNA-binding protein (SSB), which rapidly binds and continuously sequesters ssDNA, kinetically blocking RecA assembly. This dynamic self-assembly on a DNA lattice, in competition with another protein, is unique for the RecA family compared to other filament-forming proteins such as actin and tubulin. The complexity of this process has hindered our understanding of RecA filament assembly because ensemble measurements cannot reliably distinguish between the nucleation and growth phases, despite extensive and diverse attempts. Previous single-molecule assays have measured the nucleation and growth of RecA--and its eukaryotic homologue RAD51--on naked double-stranded DNA and ssDNA; however, the template for RecA self-assembly in vivo is SSB-coated ssDNA. Using single-molecule microscopy, here we directly visualize RecA filament assembly on single molecules of SSB-coated ssDNA, simultaneously measuring nucleation and growth. We establish that a dimer of RecA is required for nucleation, followed by growth of the filament through monomer addition, consistent with the finding that nucleation, but not growth, is modulated by nucleotide and magnesium ion cofactors. Filament growth is bidirectional, albeit faster in the 5'→3' direction. Both nucleation and growth are repressed at physiological conditions, highlighting the essential role of recombination mediators in potentiating assembly in vivo. We define a two-step kinetic mechanism in which RecA nucleates on transiently exposed ssDNA during SSB sliding and/or partial dissociation (DNA unwrapping) and then the RecA filament grows. We further demonstrate that the recombination mediator protein pair, RecOR (RecO and RecR), accelerates both RecA nucleation and filament growth, and that the introduction of RecF further stimulates RecA nucleation

HUBUNGAN PENGETAHUAN IBU DENGAN STATUS KEBERSIHAN GIGI DAN MULUT PADA ANAK UMUR 3-5 TAHUN GAMPONG PEUNITI KOTA BANDA ACEH

Mothers have a role in preventing plaque accumulation in children. Based on initial data obtained from interviews with 10 mothers with children aged 3-5 years in Peuniti Village, 60% of mothers still lack knowledge in maintaining children's dental hygiene. Based on the dental hygiene examination, the 10 children examined on average had dental hygiene status with a score of 40 bad categories so that there was a gap between the targets set by the government. This study aims to determine the relationship between mother's knowledge and the dental hygiene status of children aged 3-5 years in Peuniti Village. This research is analytic with a cross sectional study approach. Sampling using total sampling, namely all children aged 3-5 years and their mothers as respondents amounted to 49 people in Peuniti Village. The research instrument used a questionnaire and a diagnostic set. Data analysis used Chi-Square statistical test. The results showed that from 49 mothers, 15 people (30.6%) had poor knowledge with the results of dental hygiene examinations in very poor categories, 18 children (36.7%) with chi-square test results p value = 0.005. It can be concluded that there is a significant relationship between maternal knowledge and dental hygiene status. It is recommended to mothers to be able to improve their child's dental care by seeking information through mass media and electronic media and conducting regular dental check- up

HUBUNGAN PENGETAHUAN ORANG TUA DENGAN GIGI BERJEJAL DI SDN LAMSAYEUN ACEH BESAR

Parents should play an active role in supervising their children's dental and oral health care. Based on preliminary data conducted on 12 students of SDN Lamsayeun Kec. Want Jaya Kab. Aceh Besar got the results that 9 of his teeth had crowding teeth. The purpose of this study was to determine the relationship of parental knowledge with crowding teeth in grade I, II and III children at SDN Lamsayeun, Want Jaya District, Aceh Besar district. This research is analytic with a cross sectional design, carried out on 8 to 12 November 2021. The population and sample are all students in grades I, II and III totaling 40 students and their parents. The results showed that students with dominant crowding had parents with sufficient knowledge as many as 9 respondents (100%). Meanwhile, students with dominant crowding had parents with poor knowledge of 13 respondents (54.2%) and students who did not experience dominant crowding had mothers with poor knowledge of 11 respondents (45.8%).The results of the chi-square statistical test obtained a value of p = 0.006 (p <0.005), Based on the results of the study, it can be concluded that there is a relationship between parental knowledge and crowding of children's teeth at SDN Lamsayeun Kec. Want Jaya Kab. Aceh Besar.   &nbsp

HUBUNGAN PENGETAHUAN ORANG TUA DENGAN GIGI BERJEJAL DI SDN LAMSAYEUN ACEH BESAR

Parents should play an active role in supervising their children's dental and oral health care. Based on preliminary data conducted on 12 students of SDN Lamsayeun Kec. Want Jaya Kab. Aceh Besar got the results that 9 of his teeth had crowding teeth. The purpose of this study was to determine the relationship of parental knowledge with crowding teeth in grade I, II and III children at SDN Lamsayeun, Want Jaya District, Aceh Besar district. This research is analytic with a cross sectional design, carried out on 8 to 12 November 2021. The population and sample are all students in grades I, II and III totaling 40 students and their parents. The results showed that students with dominant crowding had parents with sufficient knowledge as many as 9 respondents (100%). Meanwhile, students with dominant crowding had parents with poor knowledge of 13 respondents (54.2%) and students who did not experience dominant crowding had mothers with poor knowledge of 11 respondents (45.8%).The results of the chi-square statistical test obtained a value of p = 0.006 (p <0.005), Based on the results of the study, it can be concluded that there is a relationship between parental knowledge and crowding of children's teeth at SDN Lamsayeun Kec. Want Jaya Kab. Aceh Besar.   &nbsp

Distinct DNA repair pathways involving RecA and nonhomologous end joining in Mycobacterium smegmatis

Mycobacterium smegmatis was used to study the relationship between DNA repair processes involving RecA and nonhomologous end joining (NHEJ). The effect of gene deletions in recA and/or in two genes involved in NHEJ (ku and ligD) was tested on the ability of bacteria to join breaks in plasmids transformed into them and in their response to chemicals that damage DNA. The results provide in vivo evidence that only NHEJ is required for the repair of noncompatible DNA ends. By contrast, the response of mycobacteria to mitomycin C preferentially involved a RecA-dependent pathway

HUBUNGAN PENGETAHUAN IBU DENGAN STATUS KEBERSIHAN GIGI DAN MULUT PADA ANAK UMUR 3-5 TAHUN GAMPONG PEUNITI KOTA BANDA ACEH

Mothers have a role in preventing plaque accumulation in children. Based on initial data obtained from interviews with 10 mothers with children aged 3-5 years in Peuniti Village, 60% of mothers still lack knowledge in maintaining children's dental hygiene. Based on the dental hygiene examination, the 10 children examined on average had dental hygiene status with a score of 40 bad categories so that there was a gap between the targets set by the government. This study aims to determine the relationship between mother's knowledge and the dental hygiene status of children aged 3-5 years in Peuniti Village. This research is analytic with a cross sectional study approach. Sampling using total sampling, namely all children aged 3-5 years and their mothers as respondents amounted to 49 people in Peuniti Village. The research instrument used a questionnaire and a diagnostic set. Data analysis used Chi-Square statistical test. The results showed that from 49 mothers, 15 people (30.6%) had poor knowledge with the results of dental hygiene examinations in very poor categories, 18 children (36.7%) with chi-square test results p value = 0.005. It can be concluded that there is a significant relationship between maternal knowledge and dental hygiene status. It is recommended to mothers to be able to improve their child's dental care by seeking information through mass media and electronic media and conducting regular dental check- up

Recombinant DNA Molecules of Bacteriophage phi X174

phi X174 DNA structures containing two different parental genomes were detected genetically and examined by electron microscopy. These structures consisted of two monomeric double-stranded DNA molecules linked in a figure 8 configuration. Such DNA structures were observed to be formed preferentially in host recA+ cells or recA+ cell-free systems. Since the host recA+ allele is required for most phi X174 recombinant formation, we conclude that the observed figure 8 molecules are intermediates in, or end products of, a phi X174 recombination event. We propose that recombinant figure 8 DNA molecules arise as a result of "single-strand aggression," are stabilized by double-strand "branch migration," and represent a specific example of a common intermediate in genetic recombination

EFEKTIVITAS PASTA GIGI BAKING SODA DAN NON BAKING SODA TERHADAP PENURUNAN STAIN PADA PEROKOK

Many people do not realize that smoking habits can affect the level of dental and oral hygiene, smoking causes abnormalities of the tongue, gums, oral mucosa, palate in the form of nicotinic stomatitis, fungal infections, and causes discoloration of the te eth. Sodium bicarbonate is a chemical compound with the formula NaHCO3 belonging to the salt group and is often found in the form of white powder crystals. Where the content of sodium bicarbonate can remove stains on smokers. The purpose of this study was to determine the effectiveness of the use of toothpaste containing baking soda and non-baking soda to reduce stains in smokers.This type of research is analytic with a quasi-experimental method. The sample was used as many as 62 people then divided into 2 groups which were then checked for staining conditions before and after the use of toothpaste containing baking soda and non -baking soda.The results showed that the average tooth staining before and after brushing using toothpaste containing baking soda showed a decrease in staining on the Lobene intensity measurement as much as 0.324, lobene area as much as 0.217, combined as much as 0.541, with p = 0.000 < = 0, 1. While the average tooth staining before and after using non -baking soda toothpaste there was a decrease in stain on Lobene intensity measurements as much as 0.043, Lobene area as much as 0.016, combined as much as 0.059 , with p value = 0.116 > = 0.1.This study concluded that the use of toothpaste containing baking soda was more effective than non-baking soda toothpaste to reduce the stain index in smokers. It is suggested that the public can use toothpaste containing baking soda as an alternative to remove stains on the teeth, and pay more attention to the status of oral hygiene. &nbsp