PCR-RFLP Markers Research Articles

Exploring the association between SLC11A1 and CARD15 gene polymorphisms and tuberculosis susceptibility in Holstein cattle

Abstract. Bovine tuberculosis (bTB) is a contagious disease that has a socio-economic impact on familial and industrial farms. Genetic selection can improve resistance against bTB. This study aimed to characterize the links between SLC11A1 and CARD15 gene polymorphisms and tuberculosis (TB) susceptibility. In total 200 animals were used (50 cases and 150 controls). Polymorphisms in the SLC11A1 and CARD15 genes were identified and analyzed with the restriction fragment length polymorphism (PCR-RFLP) method. Our results report the PstI PCR-RFLP marker for the SLC11A1-SNP1 site and the StyI PCR-RFLP marker for the CARD51-SNP1 site in Tunisian Holstein cows. Statistical analysis showed a significant association between SLC11A1-SNP1, CARD15-SNP1 and susceptibility/resistance to TB (P < 0.05). Two SLC11A1-SNP1 genotypes were susceptible to tuberculosis, i.e., the heterozygote CG and the homozygote CC, while one SLC11A1-SNP1 genotype, i.e., the GG mutated homozygote, was less susceptible to infection. Concerning the CARD15 gene, two genotypes are highly sensitive to the incidence of bovine tuberculosis, i.e., AA and AG, while the GG genotype is more beneficial and more tolerant of Mycobacterium bovis. SLC11A1 and CARD15 are two useful candidate genes associated with tuberculosis, and this information can be used to improve the health status of domestic cattle and humans.

Molecular Identification of Morus ssp. in Duhok Using Nuclear ITS Region and Chloroplast Matk Gene

Since Mulberries (Morus)is a tree species with a considerable plant variety. Molecular techniques are methods used to distinguish between species accurately, easily and quickly. This study examines a Molecular method for distinguishing different Morus species in the Duhok - Kurdistan region/ Iraq. The method is based on the use of four techniques: matK gene, the ITS region, PCR-RFLP, and SRAP markers. Twelve Morus species have been selected for this study from different region of Duhok. The ITS region's PCR result was 700 bp, but the matK gene's PCR produce was 900 bp. The same restriction site was found for all utilized cultivars when the 700bp of ITS fragment was used for PCR-RFLP with two restriction enzymes, RsaI GT/AC and HaeIII GG/CC. This study also used six combinations of SRAP markers to aid in grouping and identifying genetic similarities. The results of PCR-RFLP demonstrated an insufficient link between Morus physical appearance and genetic traits, but differences across studied cultivars could be identified using SRAP markers. Furthermore, this study demonstrated the possibility of DNA barcoding Morus cultivars, as well as additional sequence analysis and the identification of probable SNP between cultivars.

Growth hormone gene polymorphism in domestic and wild goat breeds in Kurdistan region of Iraq using PCR-RFLP and SNP markers

Growth hormone gene polymorphism in domestic and wild goat breeds in Kurdistan region of Iraq using PCR-RFLP and SNP markers

Isolation of Toxoplasma gondii in cell culture: an alternative to bioassay

Toxoplasma gondii is an apicomplexan protozoan parasite that can infect mammals and birds. The infection can cause acute toxoplasmosis and death in susceptible hosts. Bioassay using cats and mice has been the standard for the isolation of T. gondii from infected hosts for the past several decades. However, bioassay is labor-intensive, expensive, and involves using laboratory animals. To search alternative approaches and o work towards replacement of animal experiments, we summarized the key literature and conducted four experiments to isolate T. gondii in vitro by cell culture. A few heart tissue samples from animals with the highest antibody titers in a given collection were used for T. gondii isolation. These experiments included samples from five out of 51 wild ducks, four of 46 wild turkeys, six of 24 white-tailed deer, as well as from six kangaroos that had died with acute toxoplasmosis in a zoo. These experiments resulted in three isolates from five chronically infected wild ducks (60%), four isolates from four chronically infected wild turkeys (100%), one isolate from six chronically infected white-tailed deer (17%), and four isolates from six kangaroos with acute toxoplasmosis (67%). In addition, five isolates from the five chronically infected wild ducks were obtained by bioassay in mice, showing a 100% success rate, which is higher than the 60% rate by direct cell culture. These T. gondii isolates were successfully propagated in human foreskin fibroblast (HFF) or Vero cells, and genotyped by multilocus PCR-RFLP markers. The results showed that it is practical to isolate T. gondii directly in cell culture. Although the cell culture approach may not be as sensitive as the bioassay, it does provide an alternative that is simple, cost-effective, ethically more acceptable, and less time-sensitive to isolate T. gondii. In this paper we propose a procedure that may be applied and further optimized for isolation of T. gondii.

Mitochondrial uniparental inheritance achieved after fertilization challenges the nuclear-cytoplasmic conflict hypothesis for anisogamy evolution.

In eukaryotes, a fundamental phenomenon underlying sexual selection is the evolution of gamete size dimorphism between the sexes (anisogamy) from an ancestral gametic system with gametes of the same size in both mating types (isogamy). The nuclear-cytoplasmic conflict hypothesis has been one of the major theoretical hypotheses for the evolution of anisogamy. It proposes that anisogamy evolved as an adaptation for preventing nuclear-cytoplasmic conflict by minimizing male gamete size to inherit organelles uniparentally. In ulvophycean green algae, biparental inheritance of organelles is observed in isogamous species, as the hypothesis assumes. So we tested the hypothesis by examining whether cytoplasmic inheritance is biparental in Monostroma angicava, a slightly anisogamous ulvophycean that produces large male gametes. We tracked the fates of mitochondria in intraspecific crosses with PCR-RFLP markers. We confirmed that mitochondria are maternally inherited. However, paternal mitochondria enter the zygote, where their DNA can be detected for over 14 days. This indicates that uniparental inheritance is enforced by eliminating paternal mitochondrial DNA in the zygote, rather than by decreasing male gamete size to the minimum. Thus, uniparental cytoplasmic inheritance is achieved by an entirely different mechanism, and is unlikely to drive the evolution of anisogamy in ulvophyceans.

Caprine Myostatin Gene Polymorphism in Domestic and Wild Goat Breeds in Duhok Province/Kurdistan Region of Iraq Using PCR-RFLP and SNP Markers

In Iraq generally and Kurdistan region specifically, goats are an important resource for meat and milk production. It is well known that Myostatin genes (MSTN) have the essential role in growth and development due to its crucial involvement in muscle growth. The goal of this research was to reveal the polymorphism of MSTN gene in different Capra hircus breeds (native, Shami, Meriz and Kamori goat) and in wild mountain goat (Capra aegagrus) via PCR-RFLP technique and direct seqencing The MSTN (exon 1) polymorphisms were investigated in all breeds, MSTN-Dra I/RFLP revealed three genotypes AA and BB were homozygous and AB was heterozygous. The calculated genotype frequencies were 0.270, 0.368 and 0.362 for AA, BB and AB genotype respectively. The allelic frequency was 0.451 for the A allele and 0.549 for the B allele. The average of the observed heterozygosity was 0.362 and the observed homozygosity was 0.638. The sequence data of MSTN gene of Native and Shami goats revealed 31 SNPs in nonfunctional region. In addition, in exon region there was 1 SNPs in both breed samples which did not change amino acid sequence and its silence mutation. In conclusion, the result of PCR-RFLP and SNP experiments obtained in this investigation were evaluated as very useful in genotype analysis of local goat breeds/populations. Thus, DNA polymorphisms in the Myostatin gene could be used as reliable genetic marker in breeding programs in this region.

Epidemiology and isolation of viable Toxoplasma gondii strain from macropods

Wallabies and other marsupials are highly susceptible to Toxoplasma gondii. In this study, 26 macropod samples were collected (8 red kangaroos, 4 Parma wallabies, 8 red-necked wallabies, 5 albino red-necked wallabies and 1 Eastern grey kangaroo), including tissue (n = 9) and serum (n = 17) samples. According to the modified agglutination test (MAT) results (cutoff 1:25), 50% (95% Cl: 32.06–67.94%) of the macropods had T. gondii antibodies. Among them, species, survival state, and sampling date were risk factors for T. gondii susceptibility (P < 0.05). T. gondii DNA was detected in two (cases #14 and #15) of the nine cases obtained from macropod tissues. One viable T. gondii strain (TgRooCHn4) was isolated from an albino red-necked wallaby (Macropus rufogriseus, case #14) via bioassay in mice. TgRooCHn4 belongs to ToxoDB genotype #3, using the 10 multilocus PCR-RFLP markers. The ROP18 and ROP5 gene allele types of TgRooCHn4 were 2/2, which was predicted to be non-lethal to mice. The virulence of TgRooCHn4 tachyzoites was avirulent in mice. Most macropods sampled from Hernan province in 2021 and 2022 were positive with T. gondii infection. A flood occurred in July 2021 in Zhengzhou from Henan province may promote the transmission of T. gondii oocysts. To our knowledge, this is the first T. gondii strain isolated from albino red-necked wallaby. However, further investigation is required to enhance our understanding of the transmission and prevention of toxoplasmosis in sensitive zoo animals.

Two viable Toxoplasma gondii isolates from red-necked wallaby (Macropus rufogriseus) and red kangaroo (M. rufus)

Wallabies and kangaroos are susceptible to Toxoplasma gondii. However, little information concerning T. gondii infection in captive macropods is available. Three dead macropods collected from a zoo exhibited no clinical symptoms associated with toxoplasmosis. Heart fluids were tested for T. gondii antibodies using a modified agglutination test. T. gondii DNA samples derived from macropod tissues were tested by Polymerase Chain Reaction. Viable T. gondii were isolated from myocardium of macropods via mouse bioassay. Tissues (brain, lungs, or mesenteric lymph nodes) from T. gondii-positive mice were seeded into Vero cell culture flasks. The virulence of the isolated T. gondii strains was evaluated in Swiss mice. The DNA from T. gondii tachyzoites obtained from cell cultures was characterized by 10 PCR-RFLP markers and the virulence genes, ROP18 and ROP5. T. gondii antibodies were identified in two of the three macropods (Macropod#5 and #7). T. gondii DNA was obtained from the heart and lungs of Macropod#7. Two viable T. gondii strains were isolated from the myocardium of Macropus rufogriseus (Macropod#5) and M. rufus (Macropod#7) via mouse bioassay and designated as TgRooCHn2 and TgRooCHn3, respectively. TgRooCHn2 was ToxoDB genotype#3, and TgRooCHn3 was ToxoDB genotyp#2. Both 104 TgRooCHn2 and TgRooCHn3 tachyzoites had intermediate virulence in mice. M. rufogriseus (Macropod#5) and M. rufus (Macropod#7) may have been in the initial stages of toxoplasmosis, due to a recent T. gondii infection with oocysts. This study is the first to document the T. gondii ToxoDB#3 isolate in macropods. T. gondii infection in captive macropods indicates the urgent need to control the transmission of this parasite in the environment, food and water of zoo animals.

Characterization of mitochondrial 12S rRNA gene of yellow-striped chevrotain (Moschiola kathygre) and white-spotted chevrotain (Moschiola meminna) and development of a PCR-RFLP marker for the unambiguous identification of the species

Tragulids hold a significant place in the evolutionary history of mammals since they represent the basal branch of ruminants. Only three genera of tragulids are being extant to date such as Tragulus, Hyemoschus and Moschiola. In the genus Moschiola, Sri Lankan chevrotains (Moschiola meminna and Moschiola kathygre) are endemic to Sri Lanka while Moschiola indica is present in India. Sri Lankan chevrotains lack information on their population structure, distribution and molecular evidence on species identification. This leads to possible threats including habitat destruction, poaching and illegal hunting and trading under different names. In this study, genomic DNA from hair follicles was isolated from M. meminna and M. kathygre and 12S rRNA mitochondrial gene was amplified using universal primers. The PCR products were sequenced and phylogenetic analysis was done on Sri Lankan chevrotains for the first time. The sequences of Sri Lankan chevrotains share 99.7% similarity as they differ only in a single InDel present in M. meminna. In silico analysis of 12S rRNA region revealed that PCR-RFLP approach can be used to differentiate the Sri Lankan chevrotains from Indian chevrotain using the restriction enzymes; Rsa I, Sca I, Hinf I and Hind III. M. kathygre and M. meminna can be differentiated from each other by using Dra I.

EPIDEMIOLOGIC AND PUBLIC HEALTH SIGNIFICANCE OF TOXOPLASMA GONDII INFECTIONS IN BEARS (URSUS SPP.): A 50 YEAR REVIEW INCLUDING RECENT GENETIC EVIDENCE.

Toxoplasma gondii infections are common in humans and animals worldwide. The present review summarizes worldwide information on the prevalence of clinical and subclinical infections, epidemiology, and genetic diversity of T. gondii infections in bears. Seroprevalence estimates of T. gondii in black bears (Ursus americanus) are one of the highest of all animals. In Pennsylvania, seroprevalence is around 80% and has remained stable for the past 4 decades. Approximately 3,500 bears are hunted yearly in Pennsylvania alone. The validity of different serological tests is discussed based on bioassay and serological comparisons. Seroprevalence in grizzly bears (Ursus arctos) is lower than that in black bears. Even polar bears (Ursus maritimus) are infected; infections in these animals are ecologically interesting because of the absence of felids in the Arctic. Clinical toxoplasmosis in bears is rare and not documented in adult animals. The few reports of fatal toxoplasmosis in young bears need confirmation. Viable T. gondii has been isolated from black bears and a grizzly bear. The genetic diversity of isolates based on DNA from viable T. gondii isolates is discussed. Genetic typing of a total of 26 T. gondii samples from bears using 10 PCR-RFLP markers revealed 8 PCR-RFLP ToxoDB genotypes: #1 (clonal type II) in 3 samples, #2 (clonal type III) in 8 samples, #4 (haplogroup 12) in 3 samples, #5 (haplogroup 12) in 3 samples, #74 in 5 samples, #90 in 1 sample, #147 in 1 sample, and #216 in 2 samples. These results suggest relatively high genetic diversity of T. gondii in bears. Overall, T. gondii isolates in bears range from those circulating in a domestic cycle (genotypes #1 and #2) to those mainly associated with wildlife (such as genotypes #4 and #5, together known as haplogroup 12). A patient who acquired clinical Trichinella spiralis infection after eating undercooked bear meat also acquired T. gondii infection. Freezing of infected meat kills T. gondii, including the strains isolated from bears.

Comparison between single and multi-locus approaches for specimen identification in Mytilus mussels

Mytilus mussels have been the object of much research given their sentinel role in coastal ecosystems and significant value as an aquaculture resource appreciated for both, its flavour and nutritional content. Some of the most-studied Mytilus species are M. edulis, M. galloprovincialis, M. chilensis and M. trossulus. As species identification based on morphological characteristics of Mytilus specimens is difficult, molecular markers are often used. Single-locus markers can give conflicting results when used independently; not all markers differentiate among all species, and the markers target genomic regions with different evolutionary histories. We evaluated the concordance between the PCR-RFLP markers most commonly-used for species identification in mussels within the Mytilus genus (Me15-16, ITS, mac-1, 16S rRNA and COI) when used alone (mono-locus approach) or together (multi-locus approach). In this study, multi-locus strategy outperformed the mono-locus methods, clearly identifying all four species and also showed similar specimen identification performance than a 49 SNPs panel. We hope that these findings will contribute to a better understanding of DNA marker-based analysis of Mytilus taxa. These results support the use of a multi-locus approach when studying this important marine resource, including research on food quality and safety, sustainable production and conservation.

Toxoplasma gondii in invasive animals on the Island of Fernando de Noronha in Brazil: Molecular characterization and mouse virulence studies of new genotypes

This study aimed to genetically characterize and to determine virulence from Toxoplasma gondii samples from invasive animals in the Island of Fernando de Noronha, Brazil. Blood samples were collected from 21 tegu-lizard (Salvator merianae), 12 rock-cavies (Kerodon rupestris) and 154 black-rats (Rattus rattus) from the Island and MAT (cutoff 1:25) detected anti-T. gondii antibodies in 0% of the tegus (0/21); 58.3% of the rock-cavies (7/12) and 22.7% of rats (35/154). Tissue samples (brain, heart, liver and lung) from positive animals in MAT were collected for molecular analysis and for bioassay in Swiss Webster mice. After observation period, mice were euthanized, and serological detection and tissue cyst search in the brain were performed. The brain of positive animals for serological detection or tissue cyst search was cultured in MARC-145 cells for maintenance of the T. gondii isolate. No isolate was obtained from rock cavies. Nine isolates were obtained by bioassay of 35 seropositive black rats. DNA samples were extracted from rat tissues and from parasite isolates in cell culture, and genotyped using 10 PCR-RFLP markers. ToxoDB genotypes #78 (1) from rat tissue and #146 (4), #163 (2), #260 (2) and #291 (1) from cell culture were detected. Markers of genes ROP18 and ROP5 were analyzed and in vivo virulence test was conducted in mice. Analysis revealed two allele combinations, 3/1 and 3/3, indicating non-lethal T. gondii strains, which is supported by mouse virulence test.

Genotyping of Toxoplasma gondii from Stray Cats by Multilocus PCR-RFLP Techniques in Erbil city -Kurdistan Region/Iraq.

In this study, ten multilocus PCR-RFLP markers were used for genotyping of T. gondii in six cats; that were seropositive by MAT test. These markers include SAG1, SAG2 (5-SAG2, 3-SAG2 and Alt.SAG2), SAG3, BTUB, GRA6, c22-8, c29-2, L358, PK1 and Apico. Eight T. gondii reference strains (GT1, PTG, CTG, TgCgCa1, MAS, TgCatBr5, TgCatBr64 and TgToucan) were used as positive controls for genotyping. Sample A20-1 was type III by one marker (GRA6), while sample A9-2 was type III by four markers (SAG3, BTUB, c22-8 and c29-2) and sample A20-2 was type III by four markers (SAG1, SAG3, BTUB and c29-2). Hence, it could be concluded that the strain of T. gondii in Kurdistan stray cats is likely the type III.

Genetic Homogenity of Commerson’s Anchovy (Stolephorus commersonnii) in Segara Anakan Cilacap Central Java Inferred from PCR-RFLP Markers

Commerson’s anchovy (Stolephorus commersonnii) is a small pelagic fish that live in a group and its existence is very abundant in Segara Anakan Cilacap. This anchovy is widely consumed by communities live around Segara Anakan. This leads to a high exploitation rate. Exploited populations generally have low genetic diversity. This study aims to evaluate genetic diversity of commerson’s anchovy population in Segara Anakan Cilacap inferred from PCR-RFLP of the cytochrome c oxidase 1 (CO1) gene. This study was conducted from January to April 2018 and used survey method by applying random sampling. As many as 30 samples of anchovy were taken. Genomic mtDNA was isolated using modified Chelex method. Partial sequences of the COI gene were amplified using a pair forward commercially available primer. The lengths of 650 base pair of the PCR products were digested with four restriction enzymes. The HindIII enzyme produces PCR-RFLP fragment with the size of 416 bp and 234 bp lengths, VspI produces 435 bp and 214 bp, CO1-TaqI produces 556 bp and 94 bp and RsaI produces 319 bp, 183 bp, and 148 bp fragments, respectively. The PCR-RFLP fragments were obtained from all samples but they produced uniform band pattern for all 30 anchovy individuals. These results indicated that the anchovy population in Segara Anakan Cilacap has monomorphic allele for all PCR-RFLP markers. Hence, it can be concluded that genetic homogenity was observed on anchovy population in Segara Anakan Cilacap as inferred from PCR-RFLP COI gene.

Toxoplasma gondii in four captive kangaroos (Macropus spp.) in China: Isolation of a strain of a new genotype from an eastern grey kangaroo (Macropus giganteus).

Marsupials are highly susceptible to Toxoplasma gondii infection. Here, we report T. gondii infection in four kangaroos from a zoo in China. Kangaroos were imported into China in 2000 and were since bred in zoo. In 2017–2018, four kangaroos died due to respiratory system disease or injury. The bodies were submitted to the laboratory to test for T. gondii infection. Antibodies to T. gondii were found in 75% (3/4) of the kangaroos via the modified agglutination test with the cut-off 1:25. Cysts were observed in the histopathological sections of tongue and diaphragm or squashes of fresh myocardium in two kangaroos. These cysts were confirmed as T. gondii by immunohistochemical staining and molecular biological analysis. One viable T. gondii strain was isolated from one kangaroo and designated as TgRooCHn1. DNA from T. gondii tachyzoites obtained from cell culture was characterized by 10 PCR-RFLP markers and the virulence genes ROP5 and ROP18. The genotype of this isolate did not match with any known genotypes; it was designated as ToxoDB#292. The virulence of TgRooCHn1 (104 tachyzoites) was non-lethal to mice, and it formed tissue cysts. To our knowledge, the present study is the first isolation of ToxoDB#292 strain from kangaroo. Improvemets for captive settings were initiated, including greater attention being paied to birds and stray cats, fed frozen meat for carnivores.

Comparison of Molecular Markers ISSR, SSR and RFLP to Study the Genetic Variation of Strawberry Cultivars

Strawberry is grown in Indonesia because it has potential high economic value. The purpose of this study was to investigate relationship of phenetic lineage and genetic variations in 12 strawberry cultivars using three different molecular marker methods, including ISSR, SSR and RFLP. Five primers of ISSR markers were used and they generated 53 bands with 44 polymorphic DNA bands. Percentage of polymorphic using ISSR method was 83%. Five primers of SSR markers were used and they gave 41 DNA bands with 36 polymorphic DNA bands. Percentage of polymorphic using SSR method was 87%. Four primers of PCR-RFLP markers and 3 enzymes were used and they had 20 DNA bands with 9 polymorphic DNA bands. Percentage of polymorphic PCR-RFLP method was 45%. Three dendrogram results based on each method indicated that Stroberi Hitam has smallest similarity index compared with other eleven cultivars. 'Californica' cultivar had the closest similarity with Stroberi Hitam. Data analysis of molecular character requires complementary and supporting data of other characters such as morphology, biochemistry and cytology so this will strengthen the lineage data of the organisms to be investigated. Molecular marker can be used as a good method for genetic variation analysis if it has some advantages such as high polymorphism, codominance and specific characteristics and wide distribution.

The genetic status of the Hungarian brown trout populations: exploration of a blind spot on the European map of Salmo trutta studies.

BackgroundAnalyses of the control region sequences of European brown trout populations’ mitrochondrial DNA have revealed five main evolutionary lineages (Atlantic, Danubian, Mediterranean, Adriatic, Marble) mostly relating to the main water basins; however, the hybridization between lineages were increasingly reported. Due to the hydrogeography of Hungary, wild populations should theoretically belong to the Danubian lineage, however, this has not been verified by genetic studies.MethodsIn our study multiple molecular marker sets (mitochondrial sequence, microsatellites, PCR-RFLP of nuclear markers and sex marker) were used to investigate the genetic composition and population genetics of the brown trout populations in two broodstocks, six wild streams in Hungary and one Serbian population.ResultsThe admixture of Atlantic and Danubian lineages in these populations, except the Serbian population with pure Danubian origin, was observed by control region sequences of mitochondrial DNA and PCR-RFLP markers in the nuclear genome, and one unpublished Danubian haplotype was found in Hungarian populations. A sex-specific marker revealed equal gender ratio in broodstocks and Kemence stream, whereas in other wild streams the proportion of female individuals were less than 50%. Structure and principal component analyses based on the alleles of microsatellite loci also revealed overlapping populations, however the populations were still significantly different from each other and were mostly in Hardy-Weinberg equilibrium.DiscussionStocking and migration can have a significant genetic impact on trout populations of wild streams, however there are no guidelines or common practices for stocking of small streams in Hungary, thus the genetic background of these populations should be considered when developing conservation actions.

Population structure of Toxoplasma gondii in Argentina

The protozoan Toxoplasma gondii is worldwide distributed showing a particular population structure that may differ among continents and countries. The aim of this study was to analyze the T. gondii population structure in Argentina and compare it with genotyping information from other South American countries. For the analysis, 39 samples from Argentina (isolates from the provinces of Buenos Aires, Misiones, Entre Ríos and San Luis) were genotyped using 10 multilocus PCR-RFLP markers including SAG1, SAG2 (5′-3′SAG2, alt. SAG2), SAG3, BTUB, GRA6, C22-8, C29-2, L358, PK1, and Apico. The T. gondii DNA samples were obtained from domestics animals (chickens n = 20; cats n = 3; pigs n = 2; goat n = 1; rabbit n = 1), humans (n = 6), zoo animals (n = 5) and a rat (n = 1). Phylogenetic relationship of these Argentinean isolates together with representative reference genotypes was determined by phylogenetic network analysis. Thirty-seven Argentinean samples belonged to 21 genotypes and two samples were genotyped at 8 of the 10 loci and considered incomplete characterized. Among these 37 typed samples, five genotypes were not previously reported. The majority of the samples grouped with the Type III (ToxoDB PCR-RFLP genotype #2) lineage. The clonal Type II (ToxoDB genotypes #1 and #3) was also identified. Our results suggest a unique population structure with combination of unique genotypes and the common Type II and Type III lineages in Argentina. Nevertheless, different regions showed distinctive pattern of genotypes, revealing a higher variability in Northern provinces.

Free-range chickens from Santa Catarina state, southern Brazil, as asymptomatic intermediate hosts for Toxoplasma gondii clonal type I and typical Brazilian genotypes.

Chickens are a host that is very resistant to the development of clinical toxoplasmosis. Free-range chickens have been used to indirectly track environmental contamination with Toxoplasma gondii oocysts because they feed on the ground. This study evaluated the genetic diversity of T. gondii isolates from free-range chickens from Florianópolis island in Santa Catarina state, southern Brazil. Sera from 21 chickens were tested for IgG anti-T. gondii antibodies using the modified agglutination test (MAT). Tissue homogenates from the 11 seropositive birds (MAT titres ≥5) were bioassayed in mice. The four obtained isolates (TgCkBrSC1-4) were genotyped using 11 PCR-RFLP markers and 15 microsatellite markers (MS). Four genotypes were identified, three of which are typical Brazilian genotypes (ToxoDB-RFLP #26 and #53 were previously reported and #278 is new), and the other is the rare clonal type I genotype. This type I isolate was considered a variant according to MS analysis, with two atypical alleles, which emphasizes the genetic diversity of the parasite in Brazil. The genetic variability of T. gondii in South America may be related to the high occurrence of severe ocular and congenital toxoplasmosis in humans in this region. High human seroprevalence and frequency of ocular toxoplasmosis are reported in southern Brazil, but there is limited information on the T. gondii strains that are circulating in this region, so more studies should be conducted to identify the strains in different hosts and in human toxoplasmosis cases.

Detection of pea wilt pathogen Fusarium oxysporum f. sp. pisi using DNA-based markers

Identification of the fungus Fusarium oxysporum f. sp. pisi (Fop), the causal organism of wilt disease of pea, is a time consuming and arduous task. Diagnosis of Fop by traditional means requires more than 2 months and involves two steps, identification of species using morphological characters and formae specialis ‘pisi’ using pathogenicity assays. The ambiguous morphological differences between F. solani and F. oxysporum further complicate the diagnosis of F. oxysporum. A polymerase chain reaction–restriction fragment length polymorphism (PCR–RFLP) based method was developed to detect Fop from India. A PCR–RFLP marker, HPACAPS1380, generated after restriction of 28S rDNA region with enzyme MvaI, detected accurately the Fop among several other fungi with detection sensitivity of 5 fg of Fop genomic DNA. In a mixture of Fop and pea DNA, the sensitivity was 500 pg of Fop DNA in 50 ng of pea DNA. The assay was further refined to detect the Fop from infected tissues and infested soil. The current assay can detect Fop from culture, plant tissues and soil in a considerably shorter period of time compared to traditional methods.