RESUMEN
We report here the complete annotated 6,035,547-bp draft genome sequence of Bacillus thuringiensis INTA Fr7-4. This strain contains three cry8 and two vip1 and vip2 insecticidal toxin genes.
RESUMEN
We report the complete sequence and analysis of pFR260, a novel megaplasmid of 260,595 bp from the Bacillus thuringiensis strain INTA Fr7-4 isolated in Argentina. It carries 7 insecticidal genes: 3 cry8 copies previously reported, 2 vip1, and 2 vip2. Also, it carries a gene encoding a putative atypical Cry protein. These genes are arranged in a region of approximately 105 kbp in size with characteristics of a pathogenicity island with a potential coleopteran-specific insecticide profile. DNA strand composition asymmetry, as determined by GC skew analysis, and the presence of a Rep protein involved in the initiation of replication suggest a bidirectional theta mechanism of replication. In addition, many genes involved in conjugation and a CRISPR-Cas system were detected. The pFR260 sequence was deposited in GenBank under accession number KX258624.
Asunto(s)
Bacillus thuringiensis/genética , Proteínas Bacterianas/genética , Endotoxinas/genética , Orden Génico , Proteínas Hemolisinas/genética , Plásmidos , Análisis de Secuencia de ADN , Argentina , Bacillus thuringiensis/aislamiento & purificación , Toxinas de Bacillus thuringiensis , Sistemas CRISPR-Cas , Conjugación Genética , ADN Helicasas/genética , Replicación del ADN , ADN Bacteriano/química , ADN Bacteriano/genética , Islas GenómicasRESUMEN
Geobacillus sp. isolate T6 was collected from a thermal spring in Salta, Argentina. The draft genome sequence (3,767,773 bp) of this isolate is represented by one major scaffold of 3,46 Mbp, a second one of 207 kbp, and 20 scaffolds of <13 kbp. The assembled sequences revealed 3,919 protein-coding genes.
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Thermus sp. isolate 2.9 was obtained from a hot water spring in Salta, Argentina. Here, we report the draft genome sequence (2,485,434 bp) of this isolate, which consists of 11 scaffolds of >10 kbp and 2,719 protein-coding sequences.
RESUMEN
We found and characterized two cry8 genes from the Bacillus thuringiensis strain INTA Fr7-4 isolated in Argentina. These genes, cry8Kb3 and cry8Pa3, are located in a tandem array within a 13,200-bp DNA segment sequenced from a preparation of total DNA. They encode 1,169- and 1,176-amino-acid proteins, respectively. Both genes were cloned with their promoter sequences and the proteins were expressed separately in an acrystalliferous strain of B. thuringiensis leading to the formation of ovoid crystals in the recombinant strains. The toxicity against larvae of Anthonomus grandis Bh. (Coleoptera: Curculionidae) of a spore-crystal suspension from the recombinant strain containing cry8Pa3 was similar to that of the parent strain INTA Fr7-4.
Asunto(s)
Bacillus thuringiensis/aislamiento & purificación , Proteínas Bacterianas/genética , Proteínas Bacterianas/metabolismo , Endotoxinas/genética , Endotoxinas/metabolismo , Proteínas Hemolisinas/genética , Proteínas Hemolisinas/metabolismo , Animales , Argentina , Bacillus thuringiensis/genética , Toxinas de Bacillus thuringiensis , Clonación Molecular , Escarabajos/efectos de los fármacos , Expresión Génica , Regiones Promotoras Genéticas , Proteínas Recombinantes/genética , Proteínas Recombinantes/metabolismo , Análisis de Secuencia de ADN , Análisis de SupervivenciaRESUMEN
Insecticidal activity of Bacillus thuringiensis is attributed largely to the crystal proteins. These were found with specific toxic activity against insects in different orders. A novel cry8 gene from B. thuringiensis strain INTA Fr7-4 from Argentina was characterized. The encoded protein, Cry8Qa2, is 1184 amino acids long and its sequence is more similar to those of Cry8F class. We cloned and expressed the protein in an acrystalliferous strain of B. thuringiensis using two differentially regulated promoters. The recombinant strains produced ovoid crystals with low toxicity against larvae of Anticarsia gemmatalis (Lepidoptera: Noctuidae). The morphology and insecticidal properties of these crystals resembled those produced by the native strain INTA Fr7-4.
Asunto(s)
Bacillus thuringiensis/genética , Bacillus thuringiensis/metabolismo , Proteínas Bacterianas/genética , Proteínas Bacterianas/metabolismo , Endotoxinas/genética , Endotoxinas/metabolismo , Proteínas Hemolisinas/genética , Proteínas Hemolisinas/metabolismo , Secuencia de Aminoácidos , Animales , Argentina , Toxinas de Bacillus thuringiensis , Bioensayo , Clonación Molecular , Análisis por Conglomerados , ADN Bacteriano/química , ADN Bacteriano/genética , Expresión Génica , Lepidópteros/efectos de los fármacos , Datos de Secuencia Molecular , Filogenia , Análisis de Secuencia de ADN , Homología de Secuencia de Aminoácido , Análisis de SupervivenciaRESUMEN
Bacillus thuringiensis is an insect pathogen used worldwide as a bioinsecticide. It belongs to the Bacillus cereus sensu lato group as well as Bacillus anthracis and B. cereus. Plasmids from this group of organisms have been implicated in pathogenicity as they carry the genes responsible for different types of diseases that affect mammals and insects. Some plasmids, like pAW63 and pBT9727, encode a functional conjugation machinery allowing them to be transferred to a recipient cell. They also share extensive homology with the non-functional conjugation apparatus of pXO2 from B. anthracis. In this study we report the complete sequence of three plasmids from an environmental B. thuringiensis isolate from Argentina, obtained by a shotgun sequencing method. We obtained the complete nucleotide sequence of plasmids pFR12 (12,095bp), pFR12.5 (12,459bp) and pFR55 (55,712bp) from B. thuringiensis INTA-FR7-4. pFR12 and pFR12.5 were classified as cryptic as they do not code for any obvious functions besides replication and mobilization. Both small plasmids were classified as RCR plasmids due to similarities with the replicases they encode. Plasmid pFR55 showed a structural organization similar to that observed for plasmids pAW63, pBT9727 and pXO2. pFR55 also shares a tra region with these plasmids, containing genes related to T4SS and conjugation. A comparison between pFR55 and conjugative plasmids led to the postulation that pFR55 is a conjugative plasmid. Genes related to replication functions in pFR55 are different to those described for plasmids with known complete sequences. pFR55 is the first completely sequenced plasmid with a replication machinery related to that of ori44. The analysis of the complete sequence of plasmids from an environmental isolate of B. thuringiensis permitted the identification of a near complete conjugation apparatus in pFR55, resembling those of plasmids pAW63, pBT9727 and pXO2. The availability of this sequence is a step forward in the study of the molecular basis of the conjugative process in Gram positive bacteria, particularly due to the similarity with known conjugation systems. It is also a contribution to the expansion of the non-pathogenic B. cereus plasmid gene pool.
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Bacillus cereus/genética , Bacillus thuringiensis/genética , Plásmidos/genética , Secuencia de Bases , Datos de Secuencia Molecular , Plásmidos/aislamiento & purificaciónRESUMEN
Anastrepha fraterculus is an important pest of commercial fruits in South America. The variability observed for morphological and behavioural traits as well as genetic markers suggests that A. fraterculus represents a complex of synmorphic species rather than a single biological species. We studied the correlation between geographical distribution and genetic variation in natural populations from Argentina and south Brazil. Fragments of the mitochondrial gene COII were sequenced in 28 individuals. The matrix of aligned sequences was phylogenetically analysed by parsimony, yielding a cladogram of haplotypes. Based on Templeton's nested method, no clade showed any geographic pattern for the gene COII, indicating lack of significant association between haplotypic variability and geographic distribution. The analysis of nucleotide substitution distances by Neighbour-Joining algorithm showed that geographically distant populations exhibit low genetic distances. The corresponding trees clustered the populations without showing any geographic pattern. This result suggests that the populations studied are not reproductively isolated.
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Variación Genética , Tephritidae/clasificación , Tephritidae/genética , Animales , Argentina , Brasil , ADN Mitocondrial/genética , Complejo IV de Transporte de Electrones/genética , Genes Mitocondriales , Haplotipos , Filogenia , Población , Tephritidae/anatomía & histologíaRESUMEN
A feasible and fully described strategy, with a detailed list of primers, for amplifying, cloning and sequencing known and potentially novel cry1A genes harboured by a Bacillus thuringiensis strain was successfully established. Based on the analysis of conserved regions of the cry1A genes, the 1AF and 1UR oligonucleotide primers were designed to amplify the whole open reading frame of these genes. The PCR products obtained revealed the successful amplification of cry1A genes from 13 B. thuringiensis strains. These bacteria were previously known to harbour at least one cry1A gene. An Argentinean B. thuringiensis isolate INTA Mo1-12 was randomly chosen for cloning and sequencing of cry1A genes by using a primer set developed in this study. Both nucleotide and amino acid sequences similarity analysis revealed that cry1Aa and cry1Ac from B. thuringiensis INTA Mo1-12 are new natural variants, showing several differences with the other known cry1A subclasses. These genes were named by the B. thuringiensis Pesticidal Crystal Protein Nomenclature Committee as cry1Aa15 and cry1Ac21 respectively.
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Bacillus thuringiensis/metabolismo , Proteínas Bacterianas/metabolismo , Toxinas Bacterianas/metabolismo , Endotoxinas/metabolismo , Proteínas Hemolisinas/metabolismo , Secuencia de Aminoácidos , Toxinas de Bacillus thuringiensis , Proteínas Bacterianas/aislamiento & purificación , Toxinas Bacterianas/aislamiento & purificación , Endotoxinas/aislamiento & purificación , Proteínas Hemolisinas/aislamiento & purificación , Datos de Secuencia MolecularRESUMEN
A method to amplify long genomic regions (up to approximately 12.3 kb) from pestiviruses in one RT-PCR is described. The difficulty in designing conserved Pestivirus primers for the amplification of genomes from highly divergent isolates simply by means of overlapping segments is demonstrated using new bioinformatic tools. An alternative procedure consisting of optimizing the length of the genomic cDNA fragments and their subsequent amplification by polymerase chain reaction (PCR) using a limited set of specific primers is described. The amplification of long DNA fragments from a variety of sources, including genomic, mitochondrial, and viral DNAs as well as cDNA produced by reverse transcription (RT) has been achieved using this methodology, known as long distance PCR. In the case of viruses, it is necessary to obtain viral particles from infected cells prior to RT procedures. This work provides improvements in four steps of long distance RT-PCR (L-RT-PCR): (i) preparation of a viral stock, (ii) preparation of template RNA, (iii) reverse transcription and (iv) amplification of the cDNA by LD-PCR. The usefulness of L-RT-PCR is discussed in the light of current knowledge on pestivirus diversity. The genomic sequence of Singer_Arg reference strain obtained using this method is presented and characterized.