From molecules to ecosystems: Insights into a network of interactions for a Chagas disease outbreak using Triatoma brasiliensis as natural samplers.

Exploring the dynamics of disease transmission involves an understanding of complex interactions within the eco-epidemiologic framework. In the context of Chagas disease (CD), elements are mainly represented by the interactions among the pathogen, insect vector, host, humans and the environment. We performed quantitative and qualitative analyses on a dataset derived from 98 Triatoma brasiliensis infected by trypanosomatids, which were linked to a CD outbreak in the semi-arid region of northeastern Brazil. We extracted invertebrate-derived DNA (iDNA) from these insects, comprising 18 populations around the outbreak area, each indicative of various strata of anthropogenic influence. Food source (FS) diversity, representing potential parasite reservoirs, was determined through mitochondrial gene (cyt b) sequencing of vertebrates, and parasite genotyping was accessed using fluorescent amplified fragment barcodes (FFLB) of trypanosomatids. We also assessed the residents' awareness of breeding sites for CD vectors in the inspected houses. The quantification of Trypanosoma cruzi was estimated via real-time PCR and is denominated here as the average parasite load (PL) per insect (T. cruzi/intestinal unit). We aimed to address vector-parasite-host-environment interactions that were discussed based on their significance among the components. Notably, among the significant interactions, we observed that the PL in the insects was significantly influenced by FS. Infected insects that fed on the classic reservoir, Didelphis albiventris, and Galea spixii exhibited higher PLs, compared to those that fed on Kerodon rupestris (p < 0.04)-a primary host. While D. albiventris is already recognized as a synanthropic species, we propose that G. spixii may also be undergoing a synanthropic process. Conversely, domestic cats are frequently identified as FS in infected insects from the sylvatic environment, suggesting a possible change in their behavior towards a wild state. Therefore, we propose that neglected anthropogenic actions have facilitated the reciprocal (sylvatic-peridomestic) circulation of T. cruzi-especially noted for TcI because it was predominant in insects found in peridomestic environments. Residents are often unaware of the existence of insect breeding grounds near their homes, particularly when it involves the storage of materials without planning for use, such as piles of tiles, bricks and wood. Although indirect inferences about the interaction among vector-parasite-host-environment are still incipient, we highlight the potential use of vectors as natural samplers of biological and ecological components in transmitting the disease.

Karyotypical Confirmation of Natural Hybridization between Two Manatee Species, Trichechus manatus and Trichechus inunguis.

Two species of manatees are found in Northern Brazil-the Antillean manatee (Trichechus manatus), which is found along the coast from Florida to Northeastern Brazil, and the Amazonian manatee (Trichechus inunguis), endemic to the Amazon drainage basin. These species show a sympatric distribution in the region of the Marajó Archipelago, an estuarine area surrounding the Amazon River mouth. There is evidence of the occurrence of interspecific hybrids in this area, based on mitochondrial DNA analyses, although the use of nuclear markers has not corroborated this proposal. Considering that these species show very distinct karyotypes, despite being closely related (2n = 48 in T. manatus and 2n = 56 in T. inunguis), hybrids would present distinct chromosome numbers. Based on this, we conducted cytogenetic analyses using classic and molecular techniques in three calves found stranded in the Marajó Island and Amapá coast. The results showed that one of them, morphologically classified as T. inunguis, presented the correspondent karyotype, with 2n = 56. However, the other two, which were phenotypically similar to T. manatus, showed 2n = 49. Despite the same diploid number, their G-banding patterns revealed some differences. The results of the distribution of some microsatellite sequences have also confirmed the heterozygosity of some chromosomal pairs in these two individuals. These results are the first indubitable confirmation of the occurrence of natural hybrids between T. manatus and T. inunguis, and also brings about some issues concerning the viability of hybrids, considering that these two individuals do not correspond to an F1 hybrid, but instead, both presented a possible F2 karyotype.

Association Between Adherence to the MIND Diet and Cognitive Performance is Affected by Income: The ELSA-Brasil Study.

BACKGROUND: The relationship between the Mediterranean-DASH Diet Intervention for Neurodegenerative Delay (MIND) diet and cognition has not been widely investigated in low- to middle-income countries. We investigated the relationship between MIND diet and cognition in the Brazilian Longitudinal Study of Adult Health (ELSA-Brasil) baseline data. METHODS: We included 11,788 participants. MIND diet adherence was based on the intake of 15 components according to a food frequency questionnaire. We analyzed the association between MIND diet adherence and global cognition, memory, and executive function using adjusted linear regression. We examined the interaction between income and MIND diet adherence on cognition and presented income stratified analyses. RESULTS: MIND diet adherence was not associated with cognition in the whole sample. Income was an effect modifier of MIND adherence on global cognition (P=0.03) and executive function (P<0.001). For participants with high income, greater adherence was associated with better executive function [ß=0.015, 95% confidence interval (CI)=0.002; 0.028, P=0.025]; while for participants with low income, greater adherence was associated with lower global cognition (ß=-0.020, 95% CI=-0.036; -0.005, P=0.010) and executive function (ß=-0.023, 95% CI=-0.039; -0.007, P=0.004). Adherence to the MIND diet was higher among participants with high income (P<0.001). CONCLUSION: For high-income participants, greater adherence was associated with better cognitive performance; for low-income participants, greater adherence was associated with lower cognitive performance.

Alcoholic beverage consumption, changes in blood pressure, and incidence of hypertension in the Longitudinal Adult Health Study (ELSA-Brasil).

OBJECTIVES: Alcohol consumption is generally associated with increased risk of hypertension. We aimed to investigate, prospectively, the effect of alcoholic-beverage consumption on blood pressure (BP) and incidence of hypertension, after a 4-y follow-up, in participants of the Longitudinal Adult Health Study (ELSA-Brasil). METHODS: We analyzed information from 3,990 participants (ages 35-74 y), men and women, from educational and research institutions, at baseline (2008-2010) and follow-up (2012-2014). Socioeconomic, hemodynamic, anthropometric, and health data were collected. Hypertension was defined as systolic BP ≥ 140 mm Hg and/or diastolic BP ≥ 90 mm Hg and/or use of antihypertensive medication. Change in alcohol consumption (g/d) was estimated by subtracting total consumed at follow-up from total consumed at baseline, and was categorized in tertiles. RESULTS: The consumption of alcoholic beverages was associated with changes in BP and hypertension only in men. Individuals who reduced total consumption of alcohol showed a smaller increase in systolic BP (1.1 versus 2.3 mm Hg; P = 0.03) and diastolic BP (1.3 versus 2.2 mm Hg; P = 0.008) compared to individuals who increased consumption. In addition, individuals in the highest tertiles of total consumption of alcohol (odds ratio [OR], 1.62; 95% confidence interval [CI], 1.14-2.29) and consumption of beer (OR, 1.51; 95% CI, 1.07-12.13), wine (OR, 1.71; 95% CI, 1.01-2.86), and spirits (OR, 2.01; 95% CI, 1.21-3.32) showed higher odds ratios for hypertension compared to the lowest tertile. CONCLUSIONS: Increased consumption of alcoholic beverages was positively associated with increased BP levels and higher chances of developing hypertension in men.

"I don't need any treatment" - barriers to mental health treatment in the general population of a megacity.

OBJECTIVE: Most countries fail to treat individuals with psychopathologies. Investigating treatment barriers and reasons for dropout are key elements to overcoming this scenario. METHODS: A representative sample of 2,942 urban-dwelling adults was interviewed face-to-face within a cross-sectional, stratified, multistage probability survey of the general population. Psychiatric diagnosis, severity level, use of services, reasons for not seeking treatment, and treatment dropout were investigated. RESULTS: Only 23% of individuals with a psychopathology of any severity level in the last 12 months received treatment. Low perceived need for treatment (56%) was the most common reason for not seeking treatment. The most visited settings were psychiatric, other mental health care, and general medical care. Among those with a perceived need for treatment (44%), psychological barriers were the most common reason for not seeking it. Treatment dropout was more prevalent among those who visited a general medical care setting. Among individuals still in treatment, human services and psychiatric care were the most common types. Female sex was associated with structural barriers (OR = 2.1). Disorder severity was negatively associated with need barriers (OR = 0.4), and positively associated with structural barriers (OR = 2.5) and psychological barriers (OR = 2.5). CONCLUSION: Despite the need for treatment and better services, psychological barriers were the major reason for not seeking treatment. Apart from providing more specialists, investing in awareness, de-stigmatization, and information is the ultimate strategy for improving psychiatric care.

Association Between Posterior Segment Eye Diseases, Common Mental Disorders, and Depression: Cross-Sectional and Longitudinal Analyses of Brazilian Longitudinal Study of Adult Health Cohort.

BACKGROUND: Posterior segment eye diseases, such as glaucoma and retinal diseases (such as diabetic retinopathy, age-related macular degeneration, and retinal detachment), are chronic diseases that are among the major causes of visual impairment. OBJECTIVE: We investigated the prevalence of anxiety disorders, depressive disorders, and common mental disorders in these patients and also the incidence of depression. METHODS: We examined baseline (2008-2010) and follow-up (2012-2014) data from the Brazilian Longitudinal Study of Adult Health (ELSA-Brasil). We used the Clinical Interview Schedule-Revised (CIS-R) to perform International Classification of Diseases-10-based diagnoses of anxiety and depressive disorders. Common mental disorder was defined as a Clinical Interview Schedule-Revised >11. We used multinomial logistic regression models to investigate associations between eye diseases and mental disorders, adjusted by age, gender, educational level, self-reported ethnicity, cardiovascular conditions, and self-reported quality of vision. RESULTS: Out of 10,775 subjects, 249 (2.3%), 303 (2.8%), and 30 (0.3%) reported having retinal diseases, glaucoma, or both, respectively. Patients with retinal diseases and those with glaucoma and retinal diseases presented a higher prevalence of common mental disorders (relative-risk ratios of 1.7 and 3.7, respectively, P < 0.001). These patients also presented a higher incidence of depression at follow-up (relative-risk ratios of 3.0 and 5.9, respectively, P < 0.001). Patients with glaucoma presented neither a higher prevalence nor a higher incidence of mental disorders or depression. CONCLUSIONS: Retinal diseases but not glaucoma were associated with mental disorders, indicating that patients with posterior segment eye diseases require distinct management of psychiatric morbidity according to the underlying pathology.

Aortic Stiffness and Age With Cognitive Performance Decline in the ELSA-Brasil Cohort.

Background Increased aortic stiffness has been associated with cognitive decline and dementia, but the results are inconsistent. This study investigated the longitudinal association of aortic stiffness and age with decreased cognitive performance in 3 cognitive tests. Methods and Results This study included 6927 participants, with a mean age of 58.8 years at baseline (2008-2010), who participated in the second wave (2012-2014) of the ELSA-Brasil (Brazilian Longitudinal Study of Adult Health) (interval between visits ranging from 2-6 years). Cognitive performance was evaluated by Memory, Phonemic, and Semantic Verbal Fluency and Trail B Tests, applied at both cohort visits. Associations with the carotid-femoral pulse wave velocity and age at baseline were investigated using linear models with mixed effects after adjusting for confounders. After all the adjustments, including for systolic blood pressure, the interaction term carotid-femoral pulse wave velocity×time proved to be statistically significant for Memory and Verbal Fluency Tests, indicating that the higher carotid-femoral pulse wave velocity at baseline was associated with a faster decline in cognitive performance in these tests between waves. The interaction term age×time was statistically significant for all cognitive tests, suggesting that increasing age at baseline was also associated with a faster decline in cognitive performance between waves. Conclusions In this relatively young cohort, and after a relatively short interval, an increased aortic stiffness at baseline was associated with a sharper decline in cognitive performances in memory and verbal fluency, regardless of systolic blood pressure levels. This study also showed that the decline in cognitive performance was faster among older individuals than among younger ones at baseline.

Bullying among adolescents: are the victims also perpetrators?

Objective: To analyze factors associated with the prevalence of maltreatment and bullying and to identify types of involvement (verbal, physical, social, sexual, cyberbullying) among high school students aged 15 to 19 years. Methods: A cross-sectional, school-based epidemiological survey was performed. The sample included 2,293 adolescents from public and private schools in the Greater Vitoria area (state of Espírito Santo, Brazil). A modified version of the Brazilian Portuguese Olweus Bully/Victim Questionnaire was used. Results: Among maltreatment behaviors, 43.3% of adolescents reported having been victims vs. 40.4% reporting to be aggressors. Among bullying behaviors, 41% reported victimization and 29.1% aggression. The most frequent types of bullying were verbal (victim = 33.8%, bully = 23.1%), social (victim = 21.8%, bully = 16.9%), and physical bullying (victim = 15.1%, bully = 8.7%). Of those reporting to be victims, 37.5% stated that they did not react as frequently as they were attacked. Almost half of the students (50.9%) identified themselves as victims, without practicing any type of aggression against another schoolmate. School network (public or private) and gender were significantly associated with victimization and aggression behaviors. Conclusion: The adolescents identified as victims did not generally attack other students, i.e., did not identify themselves as perpetrators. The high prevalence of maltreatment and bullying detected in this study, especially the verbal, social, and physical types, underscores the need for interventions addressing bullying in schools.

Bullying among adolescents: are the victims also perpetrators?

OBJECTIVE: To analyze factors associated with the prevalence of maltreatment and bullying and to identify types of involvement (verbal, physical, social, sexual, cyberbullying) among high school students aged 15 to 19 years. METHODS: A cross-sectional, school-based epidemiological survey was performed. The sample included 2,293 adolescents from public and private schools in the Greater Vitoria area (state of Espírito Santo, Brazil). A modified version of the Brazilian Portuguese Olweus Bully/Victim Questionnaire was used. RESULTS: Among maltreatment behaviors, 43.3% of adolescents reported having been victims vs. 40.4% reporting to be aggressors. Among bullying behaviors, 41% reported victimization and 29.1% aggression. The most frequent types of bullying were verbal (victim = 33.8%, bully = 23.1%), social (victim = 21.8%, bully = 16.9%), and physical bullying (victim = 15.1%, bully = 8.7%). Of those reporting to be victims, 37.5% stated that they did not react as frequently as they were attacked. Almost half of the students (50.9%) identified themselves as victims, without practicing any type of aggression against another schoolmate. School network (public or private) and gender were significantly associated with victimization and aggression behaviors. CONCLUSION: The adolescents identified as victims did not generally attack other students, i.e., did not identify themselves as perpetrators. The high prevalence of maltreatment and bullying detected in this study, especially the verbal, social, and physical types, underscores the need for interventions addressing bullying in schools.

Gender-related dimensions of childhood adversities in the general population

Objective: Childhood adversities (CAs) comprise a group of negative experiences individuals may suffer in their lifetimes. The goal of the present study was to investigate the cluster discrimination of CAs through psychometric determination of the common attributes of such experiences for men and women. Methods: Parental mental illness, substance misuse, criminality, death, divorce, other parental loss, family violence, physical abuse, sexual abuse, neglect, physical illness, and economic adversity were assessed in a general-population sample (n=5,037). Exploratory and confirmatory factor analysis determined gender-related dimensions of CA. The contribution of each individual adversity was explored through Rasch analysis. Results: Adversities were reported by 53.6% of the sample. A three-factor model of CA dimensions fit the data better for men, and a two-factor model for women. For both genders, the dimension of family maladjustment - encompassing physical abuse, neglect, parental mental disorders, and family violence - was the core cluster of CAs. Women endorsed more CAs than men. Rasch analysis found that sexual abuse, physical illness, parental criminal behavior, parental divorce, and economic adversity were difficult to report in face-to-face interviews. Conclusion: CAs embrace sensitive personal information, clustering of which differed by gender. Acknowledging CAs may have an impact on medical and psychiatric outcomes in adulthood.

Gender-related dimensions of childhood adversities in the general population.

OBJECTIVE: Childhood adversities (CAs) comprise a group of negative experiences individuals may suffer in their lifetimes. The goal of the present study was to investigate the cluster discrimination of CAs through psychometric determination of the common attributes of such experiences for men and women. METHODS: Parental mental illness, substance misuse, criminality, death, divorce, other parental loss, family violence, physical abuse, sexual abuse, neglect, physical illness, and economic adversity were assessed in a general-population sample (n=5,037). Exploratory and confirmatory factor analysis determined gender-related dimensions of CA. The contribution of each individual adversity was explored through Rasch analysis. RESULTS: Adversities were reported by 53.6% of the sample. A three-factor model of CA dimensions fit the data better for men, and a two-factor model for women. For both genders, the dimension of family maladjustment - encompassing physical abuse, neglect, parental mental disorders, and family violence - was the core cluster of CAs. Women endorsed more CAs than men. Rasch analysis found that sexual abuse, physical illness, parental criminal behavior, parental divorce, and economic adversity were difficult to report in face-to-face interviews. CONCLUSION: CAs embrace sensitive personal information, clustering of which differed by gender. Acknowledging CAs may have an impact on medical and psychiatric outcomes in adulthood.

The latent trait of ICD-11 nicotine dependence criteria: Dimensional and categorical phenotypes.

We aimed to identify phenotypes of DSM-ICD nicotine dependence among a representative sample of lifetime weekly smokers in the largest metropolitan area in South America. Data came from 1,387 lifetime weekly smokers in the São Paulo Megacity Mental Health Survey. We used exploratory factor analysis (EFA) and latent class analysis (LCA) on ICD-11 nicotine dependence proposed criteria to explore dimensionality and phenotypes profiles, followed by logistic regression models to examine the association between latent classes and socio-demographic, psychiatric and chronic medical conditions. Analyses were performed using Mplus taking into account the complex survey design features. An unidimensional model had the best EFA fit with high loadings on all criteria. Response patterns detected by LCA indicated class differences based on severity continuum: a "non-symptomatic class" (32.0%), a "low-moderate symptomatic class" (34.9%)-with high probability of the criterion "use in larger amounts", and a "high-moderate symptomatic class" (33.1%). We found an association between high-income and the intermediate class that differs from findings in high-income countries, and high likelihood of psychiatric comorbidity among the most symptomatic smokers. The best dimensional model that pulled together nicotine dependence criteria supported a single factor, in concordance with the changes proposed for ICD-11.

The human retinoblastoma susceptibility gene (RB1): an evolutionary story in primates.

The tumor suppressor gene RB1 (Human Retinoblastoma Susceptibility Gene) plays a prominent role in normal development, gene transcription, DNA replication, repair, and mitosis. Its complete biallelic dysfunction in retinoblasts is the main cause of retinoblastoma in the human. Although this gene has been evolutionary conserved, comparisons between the reference and human RB1 coding region with its counterparts in 19 non-human primates showed 359 sites where nucleotide replacements took place during the radiation of these species. These resulted in missense substitutions in 97 codons, 91 of which by amino acids with radically different physicochemical properties. Several in frame deletions and two insertions were also observed in the N-terminal region of the pRB protein where the highest number of amino acid substitutions and radical amino changes were found. Fifty-six codons were inferred to be under negative selection and five under positive selection. Differences in codon usage showed evident phylogenetic signals, with hominids generally presenting higher indices of codon bias than other catarrhines. The lineage leading to platyrrhines and, within platyrrhines, the lineage leading to Saimiri boliviensis showed a high rate of nucleotide substitutions and amino acids. Finally, several RB1 alterations associated to retinoblastoma in the human were present in several non-human primates without an apparent pathological effect.

Intimate partner violence trends in Brazil: data from two waves of the Brazilian National Alcohol and Drugs Survey.

OBJECTIVE: To compare intimate partner violence (IPV) prevalence rates in 2006 and 2012 in a nationally representative household sample in Brazil. The associations between IPV and substance use were also investigated. METHODS: IPV was assessed using the Conflict Tactic Scale-R in two waves (2006/2012) of the Brazilian Alcohol and Drugs Survey. Weighted prevalence rates and adjusted logistic regression models were calculated. RESULTS: Prevalence rates of IPV victimization decreased significantly, especially among women (8.8 to 6.3%). The rates of IPV perpetration also decreased significantly (10.6 to 8.4% for the overall sample and 9.2 to 6.1% in men), as well as the rates of bidirectional violence (by individuals who were simultaneously victims and perpetrators of violence) (3.2 to 2.4% for the overall sample). Alcohol increased the likelihood of being a victim (odds ratio [OR] = 1.6) and perpetrator (OR = 2.4) of IPV. Use of illicit drugs increased up to 4.5 times the likelihood of being a perpetrator. CONCLUSIONS: In spite of the significant reduction in most types of IPV between 2006 and 2012, violence perpetrated by women was not significantly reduced, and the current national rates are still high. Further, this study suggests that use of alcohol and other psychoactive drugs plays a major role in IPV. Prevention initiatives must take drug misuse into consideration.

Intimate partner violence trends in Brazil: data from two waves of the Brazilian National Alcohol and Drugs Survey

Objective: To compare intimate partner violence (IPV) prevalence rates in 2006 and 2012 in a nationally representative household sample in Brazil. The associations between IPV and substance use were also investigated. Methods: IPV was assessed using the Conflict Tactic Scale-R in two waves (2006/2012) of the Brazilian Alcohol and Drugs Survey. Weighted prevalence rates and adjusted logistic regression models were calculated. Results: Prevalence rates of IPV victimization decreased significantly, especially among women (8.8 to 6.3%). The rates of IPV perpetration also decreased significantly (10.6 to 8.4% for the overall sample and 9.2 to 6.1% in men), as well as the rates of bidirectional violence (by individuals who were simultaneously victims and perpetrators of violence) (3.2 to 2.4% for the overall sample). Alcohol increased the likelihood of being a victim (odds ratio [OR] = 1.6) and perpetrator (OR = 2.4) of IPV. Use of illicit drugs increased up to 4.5 times the likelihood of being a perpetrator. Conclusions: In spite of the significant reduction in most types of IPV between 2006 and 2012, violence perpetrated by women was not significantly reduced, and the current national rates are still high. Further, this study suggests that use of alcohol and other psychoactive drugs plays a major role in IPV. Prevention initiatives must take drug misuse into consideration.

Investigating dimensionality and measurement bias of DSM-5 alcohol use disorder in a representative sample of the largest metropolitan area in South America.

BACKGROUND: Given the recent launch of a new diagnostic classification (DSM-5) for alcohol use disorders (AUD), we aimed to investigate its dimensionality and possible measurement bias in a non-U.S. METHODS: The current analyses were restricted to 948 subjects who endorsed drinking at least one drink per week in the past year from a sample of 5037 individuals. Data came from São Paulo Megacity Project (which is part of World Mental Health Surveys) collected between 2005 and 2007. First, exploratory factor analysis (EFA) was carried out to test for the best dimensional structure for DSM-5-AUD criteria. Then, item response theory (IRT) was used to investigate the severity and discrimination properties of each criterion of DSM-5-AUD. Finally, differential criterion functioning (DCF) were investigated by socio-demographics (income, gender, age, employment status, marital status and education). All analyses were performed in Mplus software taking into account complex survey design features. RESULTS: The best EFA model was a one-dimensional model. IRT results showed that the criteria "Time Spent" and "Given Up" have the highest discrimination and severity properties, while the criterion "Larger/Longer" had the lowest value of severity, but an average value of discrimination. Only female gender had DCF both at criterion- and factor-level, rendering measurement bias. CONCLUSION: This study reinforces the existence of a DSM-5-AUD continuum in the largest metropolitan area of South America, including subgroups that had previously higher rates of alcohol use (lower educational/income levels). Lower DSM-5-AUD scores were found in women.

DSM-5 latent classes of alcohol users in a population-based sample: results from the São Paulo Megacity Mental Health Survey, Brazil.

BACKGROUND: We aimed to identify different categorical phenotypes based upon the DSM-V criteria of alcohol use disorders (AUD) among alcohol users who had at least one drink per week in the past year (n=948). METHODS: Data are from the São Paulo Megacity Mental Health Survey collected in 2005-2007, as part of the World Mental Health Survey Initiative. A latent class analysis of the 11 DSM-5-AUD criteria was performed using Mplus, taking into account complex survey design features. Weighted logistic regression models were used to examine demographic correlates of the DSM-5-AUD latent classes. RESULTS: The best latent-class model was a three-class model. We found a "non-symptomatic class" (69.7%), a "use in larger amounts class" (23.2%), defined by high probability (>70%) of the "use in larger amounts" criterion only, and a "high-moderate symptomatic class" (7.1%), defined by high-moderate probability of all the 11 AUD criteria. Compared to those in the non-symptomatic class, individuals in the "high-moderate symptomatic class" were more likely to have been married, have lower educational attainment and to be unemployed or in non-regular/informal employment. Those on the "use in larger amounts class" were more likely to have been married or never married. CONCLUSION: The two symptomatic classes clearly represented the dimensionality of the new proposed AUD criteria, and could be more specifically targeted by different prevention or treatment strategies. DSM-5-AUD has the advantage of shedding light on risky drinkers included in the "use in larger amounts class", allowing for preventive interventions, which will reach a large number of individuals.

Scapteromys aquaticus (Rodentia: Sigmodontinae) in Brazil with comments on karyotype and phylogenetics relationships

The swamp rats are distributed in Argentina, southern Paraguay, Uruguay and southern Brazil, with two species currently accepted: Scapteromys aquaticus Thomas, 1920 and Scapteromys tumidus Waterhouse, 1837. While S. aquaticus occurs in Argentina, Paraguay and western Uruguay, S. tumidus occurs in Brazil and Uruguay. Here we report for the first time the occurrence of S. aquaticus in gallery forest remnants in Southern Brazil. Karyologic analysis showed 2n = 32 and FNa = 40. Phylogenetic analyses, based on DNA sequences from the mitochondrial cytochrome-b gene indicate that the Brazilian and the Argentinian specimens of S. aquaticus shared one haplotype, while median joining analysis showed lack of population structure. This register, plus the karyotype data available for Brazilian population, recovered four karyomorphotypes in Brazil, corresponding to the two known species of Scapteromys and two unnamed species. This scenario indicates that more multidisciplinary studies are necessary to understand the actual diversity of Scapteromys.(AU)

Scapteromys aquaticus (Rodentia: Sigmodontinae) in Brazil with comments on karyotype and phylogenetics relationships

The swamp rats are distributed in Argentina, southern Paraguay, Uruguay and southern Brazil, with two species currently accepted: Scapteromys aquaticus Thomas, 1920 and Scapteromys tumidus Waterhouse, 1837. While S. aquaticus occurs in Argentina, Paraguay and western Uruguay, S. tumidus occurs in Brazil and Uruguay. Here we report for the first time the occurrence of S. aquaticus in gallery forest remnants in Southern Brazil. Karyologic analysis showed 2n = 32 and FNa = 40. Phylogenetic analyses, based on DNA sequences from the mitochondrial cytochrome-b gene indicate that the Brazilian and the Argentinian specimens of S. aquaticus shared one haplotype, while median joining analysis showed lack of population structure. This register, plus the karyotype data available for Brazilian population, recovered four karyomorphotypes in Brazil, corresponding to the two known species of Scapteromys and two unnamed species. This scenario indicates that more multidisciplinary studies are necessary to understand the actual diversity of Scapteromys.