Adaptive evolution in the toxicity of a spider's venom enzymes.

BACKGROUND: Sphingomyelinase D is the main toxin present in the venom of Loxosceles spiders. Several isoforms present in these venoms can be structurally classified in two groups. Class I Sphingomyelinase D contains a single disulphide bridge and variable loop. Class II Sphingomyelinase D presents an additional intrachain disulphide bridge that links a flexible loop with a catalytic loop. These classes exhibit differences in their toxic potential. In this paper we address the distribution of the structural classes of SMase D within and among species of spiders and also their evolutionary origin by means of phylogenetic analyses. We also conducted tests to assess the action of natural selection in their evolution combined to structural modelling of the affected sites. RESULTS: The majority of the Class I enzymes belong to the same clade, which indicates a recent evolution from a single common ancestor. Positively selected sites are located on the catalytic interface, which contributes to a distinct surface charge distribution between the classes. Sites that may prevent the formation of an additional bridge were found in Class I enzymes. CONCLUSIONS: The evolution of Sphingomyelinase D has been driven by natural selection toward an increase in noxiousness, and this might help explain the toxic variation between classes.

CD226 rs763361 is associated with the susceptibility to type 1 diabetes and greater frequency of GAD65 autoantibody in a Brazilian cohort.

CD226 rs763361 variant increases susceptibility to type 1 diabetes (T1D) in Caucasians. There is no data about CD226 variants in the very heterogeneous Brazilian population bearing a wide degree of admixture. We investigated its association with T1D susceptibility, clinical phenotypes, and autoimmune manifestations (islet and extrapancreatic autoantibodies). Casuistry. 532 T1D patients and 594 controls in a case-control study. Initially, CD226 coding regions and boundaries were sequenced in a subset of 106 T1D patients and 102 controls. In a second step, two CD226 variants, rs763361 (exon 7) and rs727088 (3' UTR region), involved with CD226 regulation, were genotyped in the entire cohort. C-peptide and autoantibody levels were determined. No new polymorphic variant was found. The variants rs763361 and rs727088 were in strong linkage disequilibrium. The TT genotype of rs763361 was associated with TID risk (OR = 1.503; 95% CI = 1.135-1.991; P = 0.0044), mainly in females (P = 0.0012), greater frequency of anti-GAD autoantibody (31.9% × 24.5%; OR = 1.57; CI = 1.136-2.194; P = 0.0081), and lower C-peptide levels when compared to those with TC + CC genotypes (0.41 ± 0.30 ng/dL versus 0.70 ± 0.53 ng/dL P = 0.0218). Conclusions. The rs763361 variant of CD226 gene (TT genotype) was associated with susceptibility to T1D and with the degree of aggressiveness of the disease in T1D patients from Brazil. Ancestry had no effect.

Diabetes related phenotypes and their influence on outcomes of patients with corona virus disease 2019 (COVID-19).

INTRODUCTION: Diabetes mellitus (DM) is associated with severe forms of COVID-19 but little is known about the diabetes-related phenotype considering pre-admission, on-admission and data covering the entire hospitalization period. METHODS: We analyzed COVID-19 inpatients (n = 3327) aged 61.2(48.2-71.4) years attended from March to September 2020 in a public hospital. RESULTS: DM group (n = 1218) differed from Non-DM group (n = 2109) by higher age, body mass index (BMI), systolic blood pressure and lower O2 saturation on admission. Gender, ethnicity and COVID-19-related symptoms were similar. Glucose and several markers of inflammation, tissue injury and organ dysfunction were higher among patients with diabetes: troponin, lactate dehydrogenase, creatine phosphokinase (CPK), C-reactive protein (CRP), lactate, brain natriuretic peptide, urea, creatinine, sodium, potassium but lower albumin levels. Hospital (12 × 11 days) and intensive care unit permanence (10 × 9 days) were similar but DM group needed more vasoactive, anticoagulant and anti-platelet drugs, oxygen therapy, endotracheal intubation and dialysis. Lethality was higher in patients with diabetes (39.3% × 30.7%) and increased with glucose levels and age, in male sex and with BMI < 30 kg/m2 in both groups (obesity paradox). It was lower with previous treatment with ACEi/BRA in both groups. Ethnicity and education level did not result in different outcomes between groups. Higher frequency of comorbidities (hypertension, cardiovascular/renal disease, stroke), of inflammatory (higher leucocyte number, RCP, LDH, troponin) and renal markers (urea, creatinine, potassium levels and lower sodium, magnesium) differentiated lethality risk between patients with and without diabetes. CONCLUSIONS: Comorbidities, inflammatory markers and renal disfunction but not Covid-19-related symptoms, obesity, ethnicity and education level differentiated lethality risk between patients with and without diabetes.

Alcohol dehydrogenase activities and ethanol tolerance in Anastrepha (Diptera, Tephritidae) fruit-fly species and their hybrids.

The ADH (alcohol dehydrogenase) system is one of the earliest known models of molecular evolution, and is still the most studied in Drosophila. Herein, we studied this model in the genus Anastrepha (Diptera, Tephritidae). Due to the remarkable advantages it presents, it is possible to cross species with different Adh genotypes and with different phenotype traits related to ethanol tolerance. The two species studied here each have a different number of Adh gene copies, whereby crosses generate polymorphisms in gene number and in composition of the genetic background. We measured certain traits related to ethanol metabolism and tolerance. ADH specific enzyme activity presented gene by environment interactions, and the larval protein content showed an additive pattern of inheritance, whilst ADH enzyme activity per larva presented a complex behavior that may be explained by epistatic effects. Regression models suggest that there are heritable factors acting on ethanol tolerance, which may be related to enzymatic activity of the ADHs and to larval mass, although a pronounced environmental effect on ethanol tolerance was also observed. By using these data, we speculated on the mechanisms of ethanol tolerance and its inheritance as well as of associated traits.

The influence of population stratification on genetic markers associated with type 1 diabetes.

Ethnic admixtures may interfere with the definition of type 1 diabetes (T1D) risk determinants. The role of HLA, PTPN22, INS-VNTR, and CTLA4 in T1D predisposition was analyzed in Brazilian T1D patients (n = 915), with 81.7% self-reporting as white and 789 controls (65.6% white). The results were corrected for population stratification by genotyping 93 ancestry informative markers (AIMs) (BeadXpress platform). Ancestry composition and structural association were characterized using Structure 2.3 and STRAT. Ethnic diversity resulted in T1D determinants that were partially discordant from those reported in Caucasians and Africans. The greatest contributor to T1D was the HLA-DR3/DR4 genotype (OR = 16.5) in 23.9% of the patients, followed by -DR3/DR3 (OR = 8.9) in 8.7%, -DR4/DR4 (OR = 4.7) in 6.0% and -DR3/DR9 (OR = 4.9) in 2.6%. Correction by ancestry also confirmed that the DRB1*09-DQB1*0202 haplotype conferred susceptibility, whereas the DRB1*07-DQB1*0202 and DRB1*11-DQB1*0602 haplotypes were protective, which is similar to reports in African-American patients. By contrast, the DRB1*07-DQB1*0201 haplotype was protective in our population and in Europeans, despite conferring susceptibility to Africans. The DRB1*10-DQB1*0501 haplotype was only protective in the Brazilian population. Predisposition to T1D conferred by PTPN22 and INS-VNTR and protection against T1D conferred by the DRB1*16 allele were confirmed. Correcting for population structure is important to clarify the particular genetic variants that confer susceptibility/protection for T1D in populations with ethnic admixtures.

Associations between a common variant near the MC4R gene and serum triglyceride levels in an obese pediatric cohort.

Polymorphisms near the MC4R gene may be related to an increased risk for obesity, but studies of variations in this gene and its relation to cardiometabolic profiles and food intake are scarce and controversial. The aim of this study is to evaluate the influence of the variants rs12970134 and rs17782313 near the MC4R gene in food intake, binge eating (BE) behavior, anthropometric parameters, body composition, metabolic profile, and cardiometabolic risk factors in obese children and adolescents. This is a cross-sectional study that included obese children and adolescents. We evaluated anthropometric, metabolic parameters and cardiometabolic risk factors, including hypertension, impaired fasting glucose, hypertriglyceridemia, and low HDL-cholesterol. BE was assessed through the BE scale, and a 24-h recall was used to evaluate total caloric intake and percentage of macronutrients and types of dietary fat. The MC4R variants rs12970134 and rs17782313 were genotyped using TaqMan assay. To assess the magnitude of risk, a logistic regression adjusted for Z-BMI, age, and gender was performed, adopting the significance level of 0.05. The study included 518 subjects (52.1 % girls, 12.7 ± 2.7 years old, Z-BMI = 3.24 ± 0.57). Carriers of the variant rs17782313 exhibit increased triglyceride levels (108 ± 48 vs. 119 ± 54, p = 0.034) and an increased risk of hypertriglyceridemia (OR 1.985, 95 % CI 1.288-3.057, p = 0.002). There was no association of the SNP rs12970134 with clinical, metabolic, or nutritional parameters. The variant rs12970134 and rs17782313 did not influence food intake or the presence of BE. The variant rs17782313 is associated with an increased risk of hypertriglyceridemia in obese children and adolescents.

Clinical variability in calpainopathy: what makes the difference?

Limb girdle muscular dystrophies (LGMD) are a heterogeneous group of genetic disorders characterised by progressive weakness of the pelvic and shoulder girdle muscles and a great variability in clinical course. LGMD2A, the most prevalent form of LGMD, is caused by mutations in the calpain-3 gene (CAPN-3). More than 100 pathogenic mutations have been identified to date, however few genotype : phenotype correlation studies, including both DNA and protein analysis, have been reported. In this study we screened 26 unrelated LGMD2A Brazilian families (75 patients) through Single-Stranded Conformation Polymorphism (SSCP), Denaturing high-performance liquid chromatography (DHPLC) and sequencing of abnormal fragments which allowed the identification of 47 mutated alleles (approximately 90%). We identified two recurrent mutations (R110X and 2362-2363AG > TCATCT) and seven novel pathogenic mutations. Interestingly, 41 of the identified mutations (approximately 80%) were concentrated in only 6 exons (1, 2, 4, 5, 11 and 22), which has important implications for diagnostic purposes. Protein analysis, performed in 28 patients from 25 unrelated families showed that with exception of one patient (with normal/slight borderline reduction of calpain) all others had total or partial calpain deficiency. The effects of type of mutation, amount of calpain in the muscle, gender and ethnicity of affected patients on clinical course (age of onset and ascertainment) were analysed. Interestingly, it was observed that, on average, African-Brazilian calpainopathy patients are more severely affected than Caucasians.

Alcohol dehydrogenase activities and ethanol tolerance in Anastrepha (Diptera, Tephritidae) fruit-fly species and their hybrids

The ADH (alcohol dehydrogenase) system is one of the earliest known models of molecular evolution, and is still the most studied in Drosophila. Herein, we studied this model in the genus Anastrepha (Diptera, Tephritidae). Due to the remarkable advantages it presents, it is possible to cross species with different Adh genotypes and with different phenotype traits related to ethanol tolerance. The two species studied here each have a different number of Adh gene copies, whereby crosses generate polymorphisms in gene number and in composition of the genetic background. We measured certain traits related to ethanol metabolism and tolerance. ADH specific enzyme activity presented gene by environment interactions, and the larval protein content showed an additive pattern of inheritance, whilst ADH enzyme activity per larva presented a complex behavior that may be explained by epistatic effects. Regression models suggest that there are heritable factors acting on ethanol tolerance, which may be related to enzymatic activity of the ADHs and to larval mass, although a pronounced environmental effect on ethanol tolerance was also observed. By using these data, we speculated on the mechanisms of ethanol tolerance and its inheritance as well as of associated traits.

Identification of protein kinase C (PKC) isoforms in teleostean, amphibian and avian pigment cells.

The beta isoform of protein kinase C (PKC) has been described as the main isoform involved in the stimulation of melanogenesis in mammalian skin melanocytes. Little is known about PKC isoforms in non-mammalian pigment cells. In neopterigian fish (holostei and teleostei), PKC is associated with pigment granule aggregation within the pigment cells (skin lightening), whereas in elasmobranchs and tetrapods, the activation of PKC leads to pigment granule dispersion (skin darkening). In an attempt to a better understanding of this distinct functional behavior upon PKC activation, we decided to investigate the PKC isoforms expressed in pigment cell lines of teleost fish, amphibians and birds, using RT-PCR followed by cloning and sequencing. Our results demonstrate the presence of messenger RNA (mRNA) for the following PKC isoforms: beta 1, lambda and iota in GEM-81 cells (Carassius auratus erythrophoroma), beta 1, beta 2 and zeta in Xenopus laevis (amphibian) melanophores; beta 1 and lambda in Gallus gallus (chicken) primary melanocytes. Beta 1 PKC seems to be conserved throughout phylogeny, but the diversity of the other isoforms in the different groups may account for the functional differences after PKC activation, which are observed between teleost and tetrapod pigment cells.

Diversification of Ramphastinae (Aves, Ramphastidae) prior to the Cretaceous/Tertiary boundary as shown by molecular clock of mtDNA sequences

Partial cytochrome b and 12S rDNA mitochondrial DNA sequences of eight representatives of the Ramphastidae family were analyzed. We applied the linearized tree method to identify sequences evolving at similar rates and estimated the divergence times among some of the taxa analyzed. After excluding Ramphastos tucanus and Capito dayi from our data set, the remaining taxa presented a constant rate of DNA substitution, and branch lengths could be re-estimated with a clock constraint using the maximum likelihood method. Branch lengths were calibrated assuming that Galliformes and Piciformes split around 100 million years ago (mya). Our results indicate that Ramphastinae, and probably Capitoninae, diverged from other Piciformes in the Late Cretaceous (82 mya), suggesting that Piciformes is another avian order that survived the mass extinction event occurred 65 mya at the Cretaceous/Tertiary (K/T) boundary. The divergence times estimated within the Ramphastinae genera cover the period from the Middle Eocene (around 47 mya) through the Late Miocene (9.5 mya). Our estimate of divergence time is coincidental with the split of the African and the South American continents and other intense geologic activities and modifications of the areas which correspond to the current Neotropics. These events might have influenced the diversification of Ramphastinae in South America.

GEBPOP2: um programa para microcomputadores em linguagem basic para auxílio no ensino fundamental de genética de populaçöes

O programa para microcomputadores GENPOP2 foi desenvolvido com a finalidade de auxiliar o ensino básico da Genética de Populaçöes. Este programa é escrito inteiramente em português e simula de forma determinísta os processos de seleçäo natural, migraçäo e de equilíbrio para genes ligados ao sexo. O processo se deriva genética também é simulado, mas estocasticamente. O programa pode ser obtido gratuitamente, conforme solicitaçäo, de acordo com as instruçöes descritas no artigo

Evolutionary trends of alcohol dehydrogenase isozymes in some species of tephritid flies

Com a finalidade de se caracterizar o padräo de evoluçäo das desidrogenases alcoolicas de tefritídeos foram realizados diversos tipos de análise. Através de eletroforese em gel de amido, foram analisadas as ADHs de larvas de alguns tefritídeos e de famílias relacionadas (drosofilídeos e otitídeos). Esta análise revelou uma grande variaçäo quanto ao número de locos que produzem este tipo de enzima. Em Tomoplagia rudolfi, näo se observou qualquer atividade de ADH. Em Acinia fucata, Rachiptera limbata, Rhagoletis nova e R. conversa observou-se apenas um loco, sendo que nas duas primeiras espécies, a enzima correspondente apresentou migraçäo anódica e atividade fortemente preferencial em alcoois de cadeia longa. Esta enzima corresponde ao loco Adh-2 e apresenta comportamento semelhante ao da enzima produzida pelo loco Odh de Drosophila melanogaster. Nas duas espécies estudadas do gênero Rhagoletis, a enzima produzida pelo loco que foi denominado Adh-1 apresentou migraçäo catódica e menor especialidade por substratos alcoólicos, mas ativa principalmente em alcoois de cadeia curta, similar ao observado nas enzimas produzidas pelo loco Adh de Drosophila melanogaster. As larvas de Euxesta eluta (Otitidae)) apresentaram uma ADH que se comportava de modo similar àquela produzida pelas larvas das espécies estudadas de Rhagoletis. Em Ceratitis capitata, Anastrepha grandis, A. fraterculus e A. striata foram observados dois locos, com as características dos locos Adh-1 e Adh-2 já comentadas, mas com especificidade de substrato bem menos pronunciada. Em A. obliqua, A. serpentina e A. bistrigata, foram observados, além destes dois locos, um terceiro (Adh-3), produzindo enzimas com características de migraçäo e especificidade de substrato semelhantes às das enzimas produzidas pelo loco Adh-2. Em A. bistrigata, foi detectado, em parte dos indivíduos o que seria uma enzima correspondente a um quarto loco, com características semelhantes às da enzima produzida pelo loco Odh de D. melanogaster. Medidas de atividade específica de ADH e do conteudo de etanol (principal alcool encontrado) nos frutos hospedeiros de espécies de Anastrepha mostraram haver uma correlaçäo positiva e estatisticamente signioficante entre estes parâmetros

Biologia molecular e evolução / Molecular Biology and Evolution

O progresso no conhecimento sobre a estrutura do material genético, de sua função no desenvolvimento e na fisiologia dos organismos e de seu papel nos processos evolutivos tem ocorrido num ritmo impressionante e acelerado. Seria espantoso, para alguémformado na década de 1940, por exemplo, comparar o que se sabia então nessa área com o que se sabe hoje em dia. Felizmente, a ciência brasileira, graças a algumas Universidades e a órgãos nacionais e estrangeiros financiadores da atividade científica, está conseguindo acompanhar e participar desse processo. Este livro é uma demonstração dessas considerações. Todos os autores deste livro ensinam e pesquisam no Brasil e tratam em seus capítulos com muita clareza e atualidade de muitos aspectos da evolução e daadaptação dos organismos no nível molecular. Em uma apresentação do livro como um todo, não seria justo salientar este ou aquele aspecto do texto, pois o importante é seu conjunto, próprio de um livro em padrão internacional. Mais justo a fazer é recomendar a sua leitura e o seu estudo a todos os interessados em evolução e, especialmente, no nível molecular.

Biologia molecular e evolução / Molecular biology and evolution

O progresso no conhecimento sobre a estrutura do material genético, de sua função no desenvolvimento e na fisiologia dos organismos e de seu papel nos processos evolutivos tem ocorrido num ritmo impressionante e acelerado. Seria espantoso, para alguémformado na década de 1940, por exemplo, comparar o que se sabia então nessa área com o que se sabe hoje em dia. Felizmente, a ciência brasileira, graças a algumas Universidades e a órgãos nacionais e estrangeiros financiadores da atividade científica, está conseguindo acompanhar e participar desse processo. Este livro é uma demonstração dessas considerações. Todos os autores deste livro ensinam e pesquisam no Brasil e tratam em seus capítulos com muita clareza e atualidade de muitos aspectos da evolução e daadaptação dos organismos no nível molecular. Em uma apresentação do livro como um todo, não seria justo salientar este ou aquele aspecto do texto, pois o importante é seu conjunto, próprio de um livro em padrão internacional. Mais justo a fazer é recomendar a sua leitura e o seu estudo a todos os interessados em evolução e, especialmente, no nível molecular.

Biologia molecular e evolução

O progresso no conhecimento sobre a estrutura do material genético, de sua função no desenvolvimento e na fisiologia dos organismos e de seu papel nos processos evolutivos tem ocorrido num ritmo impressionante e acelerado. Seria espantoso, para alguémformado na década de 1940, por exemplo, comparar o que se sabia então nessa área com o que se sabe hoje em dia. Felizmente, a ciência brasileira, graças a algumas Universidades e a órgãos nacionais e estrangeiros financiadores da atividade científica, está conseguindo acompanhar e participar desse processo. Este livro é uma demonstração dessas considerações. Todos os autores deste livro ensinam e pesquisam no Brasil e tratam em seus capítulos com muita clareza e atualidade de muitos aspectos da evolução e daadaptação dos organismos no nível molecular. Em uma apresentação do livro como um todo, não seria justo salientar este ou aquele aspecto do texto, pois o importante é seu conjunto, próprio de um livro em padrão internacional. Mais justo a fazer é recomendar a sua leitura e o seu estudo a todos os interessados em evolução e, especialmente, no nível molecular.