High sugar and butter (HSB) diet induces obesity and metabolic syndrome with decrease in regulatory T cells in adipose tissue of mice.

OBJECTIVE: The purpose of the study was to develop a novel diet based on standard AIN93G diet that would be able to induce experimental obesity and impair immune regulation with high concentrations of both carbohydrate and lipids. METHODS: To compare the effects of this high sugar and butter (HSB) diet with other modified diets, male C57BL/6 mice were fed either mouse chow, or AIN93G diet, or high sugar (HS) diet, or high-fat (HF) diet, or high sugar and butter (HSB) diet for 11 weeks ad libitum. HSB diet induced higher weight gain. Therefore, control AIN93G and HSB groups were chosen for additional analysis. Regulatory T cells were studied by flow cytometry, and cytokine levels were measured by ELISA. RESULTS: Although HF and HSB diets were able to induce a higher weight gain compatible with obesity in treated mice, HSB-fed mice presented the higher levels of serum glucose after fasting and the lowest frequency of regulatory T cells in adipose tissue. In addition, mice that were fed HSB diet presented higher levels of cholesterol and triglycerides, hyperleptinemia, increased resistin and leptin levels as well as reduced adiponectin serum levels. Importantly, we found increased frequency of CD4(+)CD44(+) effector T cells, reduction of CD4(+)CD25(+)Foxp3(+) and Th3 regulatory T cells as well as decreased levels of IL-10 and TGF-ß in adipose tissue of HSB-fed mice. CONCLUSION: Therefore, HSB represents a novel model of obesity-inducing diet that was efficient in triggering alterations compatible with metabolic syndrome as well as impairment in immune regulatory parameters.

Differential expression of alpha-synuclein in the hippocampus of SHR and SLA16 isogenic rat strains.

Two inbred strains, Lewis (LEW) and Spontaneously Hypertensive Rats (SHR), are well-known for their contrasting behavior related to anxiety/emotionality. Studies with these two strains led to the discovery of the Quantitative Trait Loci (QTL) on chromosome 4 (Anxrr16). To better understand the influences of this genomic region, the congenic rat strain SLA16 (SHR.LEW-Anxrr16) was developed. SLA16 rats present higher hyperactivity/impulsivity, deficits in learning and memory, and lower basal blood pressure than the SHR strain, even though genetic differences between them are only in chromosome 4. Thus, the present study proposed the alpha-synuclein and the dopaminergic system as candidates to explain the differential behavior of SHR and SLA16 strains. To accomplish this, beyond the behavioral analysis, we performed (I) the Snca gene expression and (II) quantification of the alpha-synuclein protein in the hippocampus (HPC), prefrontal cortex (PFC), and striatum (STR) of SHR and SLA16 strains; (III) sequencing of the 3'UTR of the Snca gene; and (IV) evaluation of miRNA binding in the 3'UTR site. A Single Nucleotide Polymorphism (SNP) was identified in the 3'UTR of the Snca gene, which exhibited upregulation in the HPC of SHR compared to SLA16 females. Alpha-synuclein protein was higher in the HPC of SHR males compared to SLA16 males. The results of this work suggested that differences in alpha-synuclein HPC content could be influenced by miRNA regulation and associated with behavioral differences between SHR and SLA16 animals.

The circling mutant Pcdh15roda is a new mouse model for hearing loss.

Mouse mutagenesis is a key tool for studying gene function and several mutant alleles have been described and constitute mouse models for human hereditary diseases. Genetic hearing loss represents over 50% of all hearing loss cases in children and, due to the heterogeneity of the disorder, there is still a demand for the isolation and characterization of new genes and alleles. Here we report phenotypic and molecular characterization of a new mouse model for hereditary hearing loss. The mutant rodador, isolated by Massironi and colleagues in 2006, presents an autosomal recessive disorder characterized by deafness and balance dysfunction associated with abnormal stereocilia in the inner ear. The mutation was mapped to mouse chromosome 10, and characterization of the gene Pcdh15 revealed an AT-to-GC transition in intron 23 of mutant animals. The alteration led to the switch of a dinucleotide ApA for ApG, creating a novel intronic acceptor splice site, which leads to incorporation of eight intronic bases into the processed mRNA and alteration of the downstream reading frame. In silico analysis indicated that the mutated protein is truncated and lacks two cadherin domains, and the transmembrane and cytoplasmic domains. Real Time PCR analyses revealed a significantly reduced Pcdh15 mRNA level in the brain of mutant mice, which might be due to the mechanism of non-sense mediated decay. In man, mutations in the orthologue PCDH15 cause non-syndromic deafness and Usher Syndrome Type 1F, a genetic disorder characterized by hearing loss and retinitis pigmentosa. Rodador mouse constitutes a new model for studying deafness in these conditions and may help in the comprehension of the pathogeneses of the disease, as well as of the mechanisms involved in the morphogenesis and function of inner ear stereocilia. This is a new ENU-induced allele and the first isolated in a BALB/c background.

Comparison of vitrification and slow cooling for umbilical tissues.

The tissue cryopreservation maintains the cellular metabolism in a quiescence state and makes the conservation possible for an indefinite period of time. The choice of an appropriate cryopreservation protocol is essential for maintenance of cryopreserved tissue banks. This study evaluated 10 samples of umbilical cord, from which small fragments of tissue (Wharton's jelly and cord lining membrane) were subjected to two protocols of cryopreservation: slow cooling and vitrification. The samples were frozen for a period of time ranging from 5 to 78 days. The efficiency of cryopreservation was evaluated by testing cell viability, histological analysis, cell culture, cytogenetic analysis and comparison with the results of the fresh samples. The results showed that the slow cooling protocol was more efficient than the vitrification for cryopreservation of umbilical cord tissue, because it has caused fewer changes in the structure of tissue (edema and degeneration of the epithelium) and, despite the significant decrease cell viability compared to fresh samples, the ability of cell proliferation in vitro was preserved in most samples. In conclusion, this study showed that it is possible to cryopreserve small fragments of tissue from the umbilical cord and, to obtain viable cells capable of proliferation in vitro after thawing, contributing to the creation of a frozen tissue bank.

Interaction between high-fat diet and ethanol intake leads to changes on the fecal microbiome.

It is known that high-fat diet and alcohol intake can modulate the gut microbiota and consequently affect physiological processes such as fat storage and conditional behavior. However, the effects of the interaction between high-fat diet, its withdrawal and ethanol intake in gut microbiota remain unclear. To address this question, we used an animal model in which C57BL/6 mice were fed on standard (AIN93G) or high-sugar and -butter (HSB) diet for 8 weeks. Then, a protocol of free choice between water and a 10% alcohol solution was introduced, and the HSB diet was replaced with AIN93G in two experimental groups. This model allowed us to distinguish the individual effects of HSB diet and ethanol, and the effects of its interaction on the microbiome. The interaction of those factors was the main driver in the structure changes of the fecal microbial community. HSB diet and ethanol consumption directly affected the abundance of Firmicutes and Actinobacteria phylum, and Clostridiaceae and Coriobacteriaceae family. On the other hand, we also showed that abundance of Bacteroidales_S24-7 family and the Firmicutes/Bacteroidetes ratio were affected only by HSB diet consumption and that ethanol consumption was uniquely responsible for the bacterial translocation to the liver, indicating a breaking of the gut barrier. Finally, we also pointed out that the withdrawal of the HSB diet affects the preference for alcohol and shows a structural resilience in the fecal microbiome. These results highlight the importance of the gut microbiome modulation and its possible role on the phenotype developed by animals.

Effect of alcohol use disorder on cellular aging.

RATIONALE: Human telomeres consist of tandem repeats at chromosome ends which protect chromosomal DNA from degradation. Telomere shortening occurs as part of natural aging; however, life stressors, smoking, drug use, BMI, and psychiatric disorders could disrupt cell aging and affect telomere length (TL). In this context, studies have evaluated the effects of alcohol consumption on TL; however, results have been inconsistent, which may reflect diverse drinking cut-offs and categorizations. OBJECTIVES: To help clarify this, the present study addresses the association of TL with alcohol use disorder (AUD), drinking behaviors, lifetime stress, and chronological age. METHODS: TL was quantified as the telomere to albumin ratio (T/S ratio) obtained from peripheral blood DNA using the quantitative PCR assay, from 260 participants with AUD and 449 non-dependent healthy controls (HC) from an existing National Institute on Alcohol Abuse and Alcoholism (NIAAA) database. RESULTS: AUD participants showed shorter TL compared to HC with both, age, and AUD, as independent predictors as well as a significant AUD with age interaction effect on TL. TL was also associated with impulsiveness in AUD participants. We did not observe an association between TL and chronicity of alcohol use, alcohol doses ingested, or childhood trauma exposures in either AUD or HC, although very few HC reported a history of childhood trauma. CONCLUSION: Our results support previous findings of telomere shortening with chronic alcohol exposures and show both an effect of AUD on TL that is independent of age as well as a significant AUD by age interaction on TL. These findings are consistent with accelerated cellular aging in AUD.

Transcriptome of the Wistar audiogenic rat (WAR) strain following audiogenic seizures.

The Wistar Audiogenic Rat (WAR) is a model whose rats are predisposed to develop seizures following acoustic stimulation. We aimed to establish the transcriptional profile of the WAR model, searching for genes that help in understanding the molecular mechanisms involved in the predisposition and seizures expression of this strain. RNA-Seq of the corpora quadrigemina of WAR and Wistar rats subjected to acoustic stimulation revealed 64 genes differentially regulated in WAR. We validated twelve of these genes by qPCR in stimulated and naive (non-stimulated) WAR and Wistar rats. Among these, Acsm3 was upregulated in WAR in comparison with both control groups. In contrast, Gpr126 and Rtel1 were downregulated in naive and stimulated WAR rats in comparison with the Wistar controls. Qdpr was upregulated only in stimulated WAR rats that exhibited audiogenic seizures. Our data show that there are genes with differential intrinsic regulation in the WAR model and that seizures can alter gene regulation. We identified new genes that might be involved in the epileptic phenotype and comorbidities of the WAR model.

Polymorphisms of CYP2C9, VKORC1, MDR1, APOE and UGT1A1 genes and the therapeutic warfarin dose in Brazilian patients with thrombosis: a prospective cohort study.

BACKGROUND: There are several pharmacogenetic algorithms to determine the warfarin doses required in patients treated for thromboembolism, but they only explain 60% of dose variation, suggesting that other genes may influence the dose required. OBJECTIVES: This study aimed to evaluate the impact of clinical factors and CYP2C9*2, CYP2C9*3, VKORC1-1639G>A, MDR1 3435C>T, APOE* ε4, and UGT1A1(TA)n polymorphisms on the warfarin dose required, especially in those individuals requiring a high warfarin dose. METHODS: We studied 116 Brazilian patients who received warfarin therapy for thromboembolism. Associations between dose variability and age, body mass index (BMI), gender, use of warfarin antagonists, and genetic polymorphisms were examined. RESULTS: CYP2C9*2, CYP2C9*3, VKORC1-1639G>A, and APOE *ε4 were associated with lower warfarin doses. Of these subjects, 21% required a warfarin dose higher than 70 mg/week, which was associated with a BMI greater than 25 kg/m(2), use of warfarin antagonists, and the presence of the MDR1 3435T allele and UGT1A1(TA) 7 polymorphism. These individuals were considered to exhibit warfarin resistance. The individuals with the MDR1 3435TT genotype required a dose 21% higher than that required by 3435CT and 3435CC individuals. The UGT1A1(TA) 7 allele was positively correlated with the warfarin dose. CONCLUSION: CYP2C9*2, CYP2C9*3, VKORC1-1639G>A, and APOE *ε4 were associated with lower warfarin doses, while MDR1 3435C>T and UGT1A1(TA) n polymorphisms were associated with a requirement for higher doses. This is the first study to evaluate warfarin resistance, APOE *ε4 and UGT1A1(TA) n genotypes in the Brazilian population, and the association of these two genotypes with warfarin dose required.

Juvenile neuronal ceroid-lipofuscinosis: clinical and molecular investigation in a large family in Brazil.

OBJECTIVE: Juvenile Neuronal Ceroid-Lipofuscinosis (JNCL, CLN 3, Batten Disease) (OMIM #204200) belongs to the most common group of neurodegenerative disorders of childhood. We report the clinical data and molecular analysis of a large Brazilian family. METHOD: Family composed of two consanguineous couples and thirty-two children. Clinical data of ten JNCL patients and molecular analyses on 13 participants were obtained. RESULTS: The large 1.02 kb deletion was detected. The most severe phenotype, with autistic behavior, tics and parkinsonism was seen in a 12-year-old female and a milder phenotype in a 14-year-old male. Nyctalopia was the first symptom in one deceased child. The visual loss of six patients has been first observed in the school and not at home. CONCLUSION: The report highlights the phenotypical intrafamily variation in 10 affected children of this family. The molecular investigation of this large family in our metabolic center turned possible the diagnosis, right approach and genetic counseling.

Type 1 diabetes susceptibility determined by HLA alleles and CTLA-4 and insulin genes polymorphisms in Brazilians.

INTRODUCTION: Type 1A diabetes mellitus (T1ADM) is a multifactorial disease in which genetic and environmental aspects are important to its development. The association of genetic variations with disease has been demonstrated in several studies; however, the role of some gene loci has not yet been fully elucidated. OBJECTIVE: To compare the frequency of HLA alleles and polymorphism in CTLA-4 and insulin genes in Brazilians with T1ADM and individuals without the disease, as well as to identify genetic markers that are able to discriminate between diabetic and non-diabetic individuals. METHODS: The presence of HLA DQB1, DQA1 and DRB1 alleles, as well as the -2221 MspI polymorphism in the insulin gene and 49 A/G in the CTLA-4 gene were identified by the 'Time-resolved fluorometer' technique after hybridization with probes labeled with Eu (III) / Sm (III) and Tb (III). RESULTS: The DQB1 *0302 and DQA1 *03 alleles were identified as predisposed to T1ADM, and the DQB1 *0301 allele presented a protective effect against the disease.The DQA1 label proved to be able to differentiate between 71.13% of the diabetic and non-diabetic individuals.This value increased to 82.47% when the DQB1 label was added. No significant difference in the frequency of polymorphisms in the insulin and CTLA-4 genes was observed between the two groups. CONCLUSIONS: The genetic markers that best characterized and discriminated diabetic and non-diabetic individuals were the HLA DQA1 and DQB1.alleles.

Biomphalaria tenagophila: dynamics of populations of resistant and susceptible strains to Schistosoma mansoni, with or without pressure of the parasite.

Resistant (Taim, RS) and susceptible albino (Joinville, SC) Biomphalaria tenagophila populations were kept together, at different proportions, throughout a 18-month-period. Some of the snail groups were submitted to Schistosoma mansoni infection. The targets of this study were (a) to analyze the populational dynamics among resistant and susceptible individuals to S. mansoni; (b) to study the resistance phenotype in descendants of cross-breeding; (c) to observe whether the parasite could exert any kind of selection in those snail populations. Throughout the experiment it could be observed that the susceptible B. tenagophila strain (Joinville) underwent a selective pressure of the parasite that was negative, since the individuals showed a high mortality rate. Although B. tenagophila (Taim) population presented a higher mortality rate without pressure of the parasite, this event was compensated by a reproductive capacity. B. tenagophila Taim was more fecund than B. tenagophila Joinville and was able to transmit the resistance character to their descendants. F1 generation obtained by cross-breeding between resistant and susceptible lineages was completely resistant to S. mansoni infection, irrespective of the Taim proportion. Moreover, less than 5% of F2 progeny were susceptible to S. mansoni infection.

Juvenile neuronal ceroid-lipofuscinosis: clinical and molecular investigation in a large family in Brazil / Lipofuscinose ceróide neuronal juvenil: investigação clínica e molecular em uma família grande no Brasil

OBJECTIVE: Juvenile Neuronal Ceroid-Lipofuscinosis (JNCL, CLN 3, Batten Disease) (OMIM #204200) belongs to the most common group of neurodegenerative disorders of childhood. We report the clinical data and molecular analysis of a large Brazilian family. METHOD: Family composed of two consanguineous couples and thirty-two children. Clinical data of ten JNCL patients and molecular analyses on 13 participants were obtained. RESULTS: The large 1.02 kb deletion was detected. The most severe phenotype, with autistic behavior, tics and parkinsonism was seen in a 12-year-old female and a milder phenotype in a 14-year-old male. Nyctalopia was the first symptom in one deceased child. The visual loss of six patients has been first observed in the school and not at home. CONCLUSION: The report highlights the phenotypical intrafamily variation in 10 affected children of this family. The molecular investigation of this large family in our metabolic center turned possible the diagnosis, right approach and genetic counseling.

OBJETIVO: Lipofuscinose Ceróide Neuronal Juvenil (JNCL, CLN 3, Doença de Batten) (OMIM # 204200) pertence ao grupo mais comum de doenças neurodegenerativas na infância. É causada por mutações no gene CLN3, com padrão de herança recessiva. A deleção de 1,02 kb é a mutação mais comum. Relatamos os dados clínicos e análise molecular de uma família consanguínea numerosa. MÉTODO: Família composta por dois casais consanguíneos e trinta e duas crianças. Foram obtidos dados clínicos de dez pacientes e análises moleculares de 13 participantes. RESULTADOS: Foi detectada deleção de 1,02 kb. O fenótipo mais grave, com comportamento autista, tiques e parkinsonismo foi visto em uma paciente do sexo feminino de 12 anos e o fenótipo mais leve em um paciente do sexo masculino de 14 anos. Nictalopia foi o primeiro sintoma de uma criança falecida. A perda visual de seis pacientes foi observada pela primeira vez na escola e não em casa. CONCLUSÃO: Destaca-se a variação fenotípica intrafamiliar em 10 pacientes. A investigação molecular desta família numerosa tornou possível o diagnóstico, a abordagem correta e aconselhamento genético.

Biomphalaria tenagophila: dominant character of the resistance to Schistosoma mansoni in descendants of crossbreedings between resistant (Taim, RS) and susceptible (Joinville, SC) strains.

The aim of the present work was to study parasitological, molecular, and genetic aspects in descendants of crossbreedings between a totally resistant Biomphalaria tenagophila strain (Taim, RS) and another one highly susceptible (Joinville, SC) to Schistosoma mansoni. Descendants F1 and F2 were submitted to S. mansoni infection (LE strain). The susceptibility rates for individuals from Group F1 were 0 to 0.6%, and from Group F2 was 7.2%. The susceptible individuals from Group F2 discharged a lower number of cercariae, when compared with the susceptible parental group, and in 2 out of 9 positive snails the cercarial elimination was discontinued. In order to identify genetic markers associated with resistance the genotype of parental snails and their offspring F1 and F2 were analyzed by means of the randomly amplified polymorphic DNA method. Nevertheless, it was not possible to detect any marker associated to resistance, but the results showed that in the mentioned species the resistance character is determined by two dominant genes.

Dominant character of the molecular marker of a Biomphalaria tenagophila strain (Mollusca: Planorbidae) resistant to Schistosoma mansoni.

Biomphalaria tenagophila population from Taim (state of Rio Grande do Sul, Brazil) is totally resistant to Schistosoma mansoni, and presents a molecular marker of 350 bp by polymerase chain reaction and restriction fragment length polymorphism of the entire rDNA internal transcriber spacer. The scope of this work was to determine the heritage pattern of this marker. A series of cross-breedings between B. tenagophila from Taim (resistant) and B. tenagophila from Joinville, state of Santa Catarina (susceptible) was carried out, and their descendants F1 and F2 were submitted to this technique. It was possible to demonstrate that the specific fragment from Taim is endowed with dominant character, since the obtained segregation was typically mendelian.

Type 1 diabetes susceptibility determined by HLA alleles and CTLA-4 and insulin genes polymorphisms in Brazilians / Suscetibilidade ao diabetes tipo 1 determinada por alelos de HLA e polimorfismos nos genes CTLA-4 e insulina em brasileiros

INTRODUCTION:Type 1A diabetes mellitus (T1ADM) is a multifactorial disease in which genetic and environmental aspects are important to its development. The association of genetic variations with disease has been demonstrated in several studies; however, the role of some gene loci has not yet been fully elucidated. OBJECTIVE:To compare the frequency of HLA alleles and polymorphism in CTLA-4 and insulin genes in Brazilians with T1ADM and individuals without the disease, as well as to identify genetic markers that are able to discriminate between diabetic and non-diabetic individuals. METHODS: The presence of HLA DQB1, DQA1 and DRB1 alleles, as well as the -2221 MspI polymorphism in the insulin gene and 49 A/G in the CTLA-4 gene were identified by the "Time-resolved fluorometer" technique after hybridization with probes labeled with Eu (III) / Sm (III) and Tb (III). RESULTS: The DQB1 *0302 and DQA1 *03 alleles were identified as predisposed to T1ADM, and the DQB1 *0301 allele presented a protective effect against the disease.The DQA1 label proved to be able to differentiate between 71.13 percent of the diabetic and non-diabetic individuals.This value increased to 82.47 percent when the DQB1 label was added. No significant difference in the frequency of polymorphisms in the insulin and CTLA-4 genes was observed between the two groups. CONCLUSIONS: The genetic markers that best characterized and discriminated diabetic and non-diabetic individuals were the HLA DQA1 and DQB1.alleles.

INTRODUÇÃO: O diabetes melito tipo 1 (T1ADM) é uma doença multifatorial em que os aspectos genéticos e ambientais são importantes para o seu desenvolvimento. A associação das variações genéticas com a doença tem sido demonstrada em vários trabalhos, no entanto, o papel de alguns locos gênicos não foi ainda completamente elucidado. OBJETIVOS: Comparar a frequência de alelos do HLA e polimorfismos nos genes CTLA-4 e insulina em brasileiros com T1ADM e indivíduos sem a doença, além de identificar marcadores gênicos que sejam capazes de discriminar indivíduos diabéticos e não diabéticos. MÉTODOS: A presença dos alelos de HLA DQB1, DQA1 e DRB1, bem como dos polimorfismos -2221 MspI no gene da insulina e 49 A/G no gene CTLA-4, foram identificados por meio da técnica Time-resolved fluorometer, após hibridização com sondas marcadas com Eu (III)/Sm (III) e Tb (III). RESULTADOS: Os alelos DQB1*0302 e DQA1*03 foram identificados como sendo de predisposição ao T1ADM, e o alelo DQB1*0301 mostrou um efeito protetor à doença. Analisando somente o marcador DQA1, este mostrou ser capaz de diferenciar 71,13 por cento dos indivíduos entre diabéticos e não diabéticos, cujo valor aumentou para 82,47 por cento quando adicionado o marcador DQB1. A frequência dos polimorfismos nos genes da insulina e CTLA-4 não mostrou diferença significativa entre os dois grupos estudados. CONCLUSÕES: Os marcadores genéticos que melhor caracterizaram e discriminaram diabéticos e não diabéticos foram os alelos de HLA DQA1 e DQB1.

Biomphalaria tenagophila: dynamics of populations of resistant and susceptible strains to Schistosoma mansoni, with or without pressure of the parasite

Resistant (Taim, RS) and susceptible albino (Joinville, SC) Biomphalaria tenagophila populations were kept together, at different proportions, throughout a 18-month-period. Some of the snail groups were submitted to Schistosoma mansoni infection. The targets of this study were (a) to analyze the populational dynamics among resistant and susceptible individuals to S. mansoni; (b) to study the resistance phenotype in descendants of cross-breeding; (c) to observe whether the parasite could exert any kind of selection in those snail populations. Throughout the experiment it could be observed that the susceptible B. tenagophila strain (Joinville) underwent a selective pressure of the parasite that was negative, since the individuals showed a high mortality rate. Although B. tenagophila (Taim) population presented a higher mortality rate without pressure of the parasite, this event was compensated by a reproductive capacity. B. tenagophila Taim was more fecund than B. tenagophila Joinville and was able to transmit the resistance character to their descendants. F1 generation obtained by cross-breeding between resistant and susceptible lineages was completely resistant to S. mansoni infection, irrespective of the Taim proportion. Moreover, less than 5 percent of F2 progeny were susceptible to S. mansoni infection.

The paralysé (par) mouse neurological mutation maps to a 9 Mbp (4 cM) interval of mouse chromosome 18

The Paralysé mutation is a spontaneous neuromuscular mutation, first observed in 1980 at the Pasteur Institute, which is transmitted by the autosomal recessive par allele. Affected homozygote par/par mice rarely survive beyond 16 days of age and at the end of their life they are emaciated and completely paralyzed. Several concordant histological and physiological observations indicate that mutant mice might be good models for studying early-onset human motor neuron diseases such as spinal muscular atrophy. Linkage analysis using a set of molecular markers and two F2 crosses indicate that the mutation maps to mouse chromosome 18 in a region spanning 4 cM (or 9 megabase pairs, Mbp) between the microsatellites D18Mit140 and D18Mit33. These results positioned the par locus in a region homologous to human chromosome 18p11.22 to 18q21.32.

Biomphalaria tenagophila: dominant character of the resistance to Schistosoma mansoni in descendants of crossbreedings between resistant (Taim, RS) and susceptible (Joinville, SC) strains

The aim of the present work was to study parasitological, molecular, and genetic aspects in descendants of crossbreedings between a totally resistant Biomphalaria tenagophila strain (Taim, RS) and another one highly susceptible (Joinville, SC) to Schistosoma mansoni. Descendants F1 and F2 were submitted to S. mansoni infection (LE strain). The susceptibility rates for individuals from Group F1 were 0 to 0.6 percent, and from Group F2 was 7.2 percent. The susceptible individuals from Group F2 discharged a lower number of cercariae, when compared with the susceptible parental group, and in 2 out of 9 positive snails the cercarial elimination was discontinued. In order to identify genetic markers associated with resistance the genotype of parental snails and their offspring F1 and F2 were analyzed by means of the randomly amplified polymorphic DNA method. Nevertheless, it was not possible to detect any marker associated to resistance, but the results showed that in the mentioned species the resistance character is determined by two dominant genes.

Dominant character of the molecular marker of a Biomphalaria tenagophila strain (Mollusca: Planorbidae) resistant to Schistosoma mansoni

Biomphalaria tenagophila population from Taim (state of Rio Grande do Sul, Brazil) is totally resistant toSchistosoma mansoni, and presents a molecular marker of 350 bp by polymerase chain reaction and restriction fragment length polymorphism of the entire rDNA internal transcriber spacer. The scope of this work was to determine the heritage pattern of this marker. A series of cross-breedings between B. tenagophila from Taim (resistant) and B. tenagophila from Joinville, state of Santa Catarina (susceptible) was carried out, and their descendants F1 and F2 were submitted to this technique. It was possible to demonstrate that the specific fragment from Taim is endowed with dominant character, since the obtained segregation was typically mendelian.