Temporal trends and spatial clusters of high risk for maternal death due to COVID-19 pre and during COVID-19 vaccination in Brazil: a national population-based ecological study.

OBJECTIVE: This study comprehensively analyzed the temporal and spatial dynamics of COVID-19 cases and deaths within the obstetric population in Brazil, comparing the periods before and during mass COVID-19 vaccination. We explored the trends and geographical patterns of COVID-19 cases and maternal deaths over time. We also examined their correlation with the SARS-CoV-2 variant circulating and the social determinants of health. STUDY DESIGN: This is a nationwide population-based ecological study. METHODS: We obtained data on COVID-19 cases, deaths, socioeconomic status, and vulnerability information for Brazil's 5570 municipalities for both the pre-COVID-19 vaccination and COVID-19 vaccination periods. A Bayesian model was used to mitigate indicator fluctuations. The spatial correlation of maternal cases and fatalities with socioeconomic and vulnerability indicators was assessed using bivariate Moran. RESULTS: From March 2020 to June 2023, a total of 23,823 cases and 1991 maternal fatalities were recorded among pregnant and postpartum women. The temporal trends in maternal incidence and mortality rates fluctuated over the study period, largely influenced by widespread COVID-19 vaccination and the dominant SARS-CoV-2 variant. There was a significant reduction in maternal mortality due to COVID-19 following the introduction of vaccination. The geographical distribution of COVID-19 cases and maternal deaths exhibited marked heterogeneity in both periods, with distinct spatial clusters predominantly observed in the North, Northeast, and Central West regions. Municipalities with the highest Human Development Index reported the highest incidence rates, while those with the highest levels of social vulnerability exhibited elevated mortality and fatality rates. CONCLUSION: Despite the circulation of highly transmissible variants of concern, maternal mortality due to COVID-19 was significantly reduced following the mass vaccination. There was a heterogeneous distribution of cases and fatalities in both periods (before and during mass vaccination). Smaller municipalities and those grappling with social vulnerability issues experienced the highest rates of maternal mortality and fatalities.

Relationship between primary vaccination coverage and booster coverage against COVID-19, socio-economic indicators, and healthcare structure in Brazil.

OBJECTIVE: To investigate the relationship between vaccination coverage and booster coverage against COVID-19, socio-economic indicators, and healthcare structure in Brazil. STUDY DESIGN: This is a nationwide population-based ecological study. METHODS: We have obtained data on COVID-19 vaccination for each Brazilian state until December 22, 2022. Our outcomes of interest were primary and booster vaccination coverage. The independent variables included: human development index (HDI); Gini index; population density; unemployment rate; percentage of the population covered by primary health care (PHC); percentage of the population covered by community health workers; number of family health teams; and number of public health establishments. Statistics were performed by using a multivariable linear regression model. RESULTS: Lower rates of primary vaccination coverage were found in states with lower HDI (P = 0.048), population covered by PHC (P = 0.006), and number of public health establishments (P = 0.004). Lower rates of booster coverage were also found in states with lower population density (first booster: P = 0.004; second booster: P = 0.022), PHC (first booster: P = 0.033; second booster: P = 0.042), and public health establishments (first booster: P < 0.001; second booster: P = 0.027). CONCLUSION: Our findings showed heterogeneity in access to vaccination against COVID-19 in Brazil, with lower vaccination coverage in localities with the worst socio-economic indicators and limited healthcare resources.

Spatial clustering of low rates of COVID-19 vaccination among children and adolescents and their relationship with social determinants of health in Brazil: a nationwide population-based ecological study.

OBJECTIVE: This study aimed to investigate the spatial clusters of high and low COVID-19 vaccination rates among children and adolescents across Brazilian municipalities and their relationship to social determinants of health. STUDY DESIGN: This is a nationwide population-based ecological study. METHODS: We have obtained for each of the 5570 Brazilian municipalities data on the COVID-19 vaccination rate of children and adolescents by August 16, 2022, the Gini index, the social vulnerability index and the municipal human development index. A Bayesian empirical local model was used to identify fluctuations in the COVID-19 vaccination rates. Spatial clusters were identified using scan spatial statistic tests. The relationship among COVID-19 vaccination rates and social determinants of health was explored by using multiple linear regression models. RESULTS: Overall, 52.1% of children aged 5-11 years and 72.8% of adolescents aged 12-17 years have been fully vaccinated against COVID-19 in Brazil by mid-August 2022. There was spatial dependence on the smoothed rates for both children (I Moran 0.66; P < 0.001) and adolescent (I Moran 0.65; P < 0.001) groups. The lowest rates occurred in municipalities in the North and Northeast regions. Municipalities with a higher Gini Index, higher social vulnerability index and lower municipal human development index were more likely to have a lower COVID-19 vaccination rate for both children and adolescent groups. CONCLUSION: COVID-19 vaccination of children and adolescents was heterogeneously distributed, with spatial clusters of the lowest vaccination rates occurring mainly in municipalities with marked socio-economic disparities and social vulnerability, especially in the North and Northeast regions.

Frailty and risk of complications in head and neck oncologic surgery. Systematic review and dose-response meta-analysis.

BACKGROUND: There is emerging evidence that frail individuals present a decreased physiological reserve, decreased ability to maintain homeostasis, and increased vulnerability to stressors. The concept of frailty has become increasingly recognized as a valuable measure in oncological surgical patients, including those with head and neck cancer. Preoperative screening for frailty may provide an individualized risk assessment that can be used by an interdisciplinary team for preoperative counseling and to improve outcomes. The aim of this meta-analysis was to evaluate the relationship between frailty and the risk of major postoperative complications in frail individuals submitted to head and neck oncologic surgery. MATERIAL AND METHODS: PubMed, SCOPUS, Web of Science, Google Scholar and OpenThesis were systematically searched to identify studies that evaluated the risk of major postoperative complications in frail individuals undergoing head and neck oncologic surgery. The search was performed on August 31, 2020, without language or date restrictions. Two independent investigators screened the searched studies based on each paper's title and abstract. Relevant studies were read in full and selected according to the eligibility criteria. Frailty was assessed by modified Frailty Index (mFI-11) and major postoperative complications were measured by the Clavien-Dindo classification. We performed a categorical and dose-response meta-analysis using a random-effects model to evaluate the association between frailty and the risk of major postoperative complications in patients submitted to head and neck oncologic surgery. The results of the meta-analysis were expressed as relative risk (RR) and 95% confidence interval (95% CI). The risk of bias was assessed using the Newcastle-Ottawa Scale (NOS). RESULTS: Four studies (9,947 patients) were included in this systematic review and meta-analysis. Frail patients presented an increased risk of life-threatening complications requiring intensive care unit (ICU) admission (RR = 4.67; 95% CI 1.54-14.10) and 30-day mortality (RR = 8.10; 95% CI 2.30-28.57) compared to non-frail patients. We found evidence of dose-response trend between mFI-11 and major postoperative complications. CONCLUSIONS: Higher frailty scores are associated with a significant increase in ICU-level complications and 30-day mortality after head and neck oncologic surgery.

Socio-economic inequalities and COVID-19 incidence and mortality in Brazilian children: a nationwide register-based study.

OBJECTIVES: This study aimed to estimate the incidence and mortality rates of coronavirus disease 2019 (COVID-19) in Brazilian children and to analyze its relationship with socio-economic inequalities in a state-level analysis. STUDY DESIGN: This is a nationwide register-based study. METHODS: To estimate the incidence and mortality rates of COVID-19 in Brazilian children aged 0-19 years, we extracted data of confirmed cases and deaths from the de-identified microdata catalog and official bulletins of the 27 Brazilian states' health department websites until September 3, 2020. Social and economic inequalities were evaluated using the Social Vulnerability Index and Gini coefficient, respectively. The relationship between COVID-19 rates in Brazilian children and socio-economic vulnerability at the state level was analyzed using Spearman's rank correlation. RESULTS: Of the 3,998,055 individuals with COVID-19 included in our database, 335,279 (8.4%) were children aged 0-19 years. Eight hundred deaths in children were registered, which accounts for about 0.7% of the deaths related to COVID-19 in the country. There were important differences in the incidence and mortality rates among Brazilian regions, and a correlation between mortality rates and social (ρ = 0.519; P-value = 0.007; effect magnitude: moderate) and economic (ρ = 0.615; P-value < 0.001; effect magnitude: strong) inequalities was found in a state-level analysis. CONCLUSIONS: This population-based study showed important regional differences in COVID-19 estimates for children in Brazil and a relationship between mortality rates and socio-economic inequalities. The knowledge of sociogeographic differences in the estimates of COVID-19 is crucial to planning societal strategies and local decision-making to mitigate the effects of disease in the pediatric population.

Physical approach for a quantitative analysis of the phytosterols in free phytosterol-oil blends by X-ray Rietveld method.

This study investigates and compares the thermal phase transition and crystallization characteristics of a commercial food grade free phytosterol blend (FP) with a stigmasterol analytical standard (SS), the FP behavior in a food model system after its addition to high oleic sunflower oil (HOSO). The properties of the FP:HOSO blends were studied by differential scanning calorimetry, solid content, crystal morphology, and X-ray diffraction (XRD) measurements. The Rietveld method (RM) was applied associated with the XRD measurements to support phase analysis and the study of crystallinity degree. The materials were also characterized by means of chemical composition, such as fatty acids and triacylglycerol profiles, for HOSO, and phytosterol profile, for FP. Regarding phase behavior and crystallinity properties, FP has very similar characteristics to SS. The thermal behavior of FP:HOSO blends has two characteristic peaks, one from FP and the other from HOSO. The similarity reported in the literature between the diffraction pattern of FP and pure phytosterols is a positive characteristic for FP. A high FP concentration resulted in high supersaturation and thus the formation of small crystals. The incorporation of HOSO reduced of the large agglomeration of FP crystals and the dispersion crystalline aggregates (spherulites) of FP crystals. The application of RM in FP:HOSO blends to quantify the crystalline and amorphous phases was successfully used. The application has provided the expected value for these phases, according to the same experimental mass ratio of the blends, thereby validating the applicability of this approach in this type of material.

Spatial clustering, social vulnerability and risk of leprosy in an endemic area in Northeast Brazil: an ecological study.

BACKGROUND: Despite the global decline in the detection of leprosy cases, its incidence has remained unchanged in certain settings and requires the determination of the factors linked to its persistence. We examined the spatial and space-time distribution of leprosy and the influence of social vulnerability on the occurrence of the disease in an endemic area of Northeast Brazil. METHODS: We performed an ecological study of all leprosy cases reported by Sergipe state, Northeast Brazil from 2001 to 2015, to examine the association of the Social Vulnerability Index and the prevalence and persistence of leprosy among the State's municipalities. Socio-economic and leprosy surveillance information was collected from the Brazilian information systems, and a Bayesian empirical local model was used to identify fluctuations of the indicators. Spatial and space-time clusters were identified using scan spatial statistic tests and to measure the municipalities' relative risk of leprosy. RESULTS: Leprosy clusters and burden of disease had a strong statistical association with the municipalities' Social Vulnerability Index. Municipalities with a high social vulnerability had higher leprosy incidence, multibacillary leprosy and newly diagnosed cases with grade 2 disability than areas with low social vulnerability. CONCLUSION: Social vulnerability is strongly associated with leprosy transmission and maintenance of disease incidence. Leprosy control programmes should be targeted to the populations with high social vulnerability.

The Role of Lignocellulosic Composition and Residual Lipids in Empty Fruit Bunches on the Production of Humic Acids in Submerged Fermentations.

The aim of this research was to study the production of humic acids (HA) by Trichoderma reesei from empty fruit bunches (EFBs) of palm oil processing, with a focus on the effects of lignocellulosic content and residual lipids. EFBs from two different soils and palm oil producers were previously characterized about their lignocellulosic composition. Submerged fermentations were inoculated with T. reesei spores and set up with or without residual lipids. The results showed that the soil and the processing for removal of the palm fresh fruits were crucial to EFB quality. Thus, EFBs were classified as type 1 (higher lignocellulosic and fatty acids composition similar to the palm oil and palm kernel oil) and type 2 (lower lignocellulosic content and fatty acids composition similar to palm oil). Despite the different profiles, the fungal growth was similar for both EFB types. HA production was associated with fungal growth, and it was higher without lipids for both EFBs. The highest HA productivity was obtained from type 1 EFB (approximately 90 mg L-1 at 48 h). Therefore, the lignocellulosic composition and the nature of the residual lipids in EFBs play an important role in HA production by submerged fermentation.

Acute phase proteins and IP-10 as triage tests for the diagnosis of tuberculosis: systematic review and meta-analysis.

OBJECTIVES: We examined the data reported in studies for diagnostic purposes and to discuss whether their intended use could be extended to triage, as rule-in or rule-out tests to select individuals who should undergo further confirmatory tests. METHODS: We searched Scopus, PubMed and Web of Science with the terms 'acute phase proteins,' 'IP-10,' 'tuberculosis,' 'screening' and 'diagnosis,' extracted the sensitivity and specificity of the biomarkers and explored methodologic differences to explain performance variations. Summary estimates were calculated using random-effects models for overall pooled accuracy. The hierarchical summary receiver operating characteristic model was used for meta-analysis. RESULTS: We identified 14, four and one studies for C-reactive protein (CRP), interferon γ-induced protein 10 (IP-10) and alpha-1-acid glycoprotein (AGP). The pooled CRP sensitivity/specificity (95% confidence interval) was 89% (80-96) and 57% (36-65). Sensitivity/specificity were higher in high-tuberculosis-burden countries (90%/64%), HIV-infected individuals (91%/61%) and community-based studies (90%/62%). IP-10 sensitivity/specificity in TB vs. non-TB studies was 85%/63% and in TB and HIV coinfected vs. other lung conditions 94%/21%. However, IP-10 studies included diverse populations and a high risk of bias, resulting in very low-quality evidence. AGP had 86%/93% sensitivity/specificity. CONCLUSIONS: Few studies have evaluated CRP, IP-10 and AGP for the triage of symptomatic patients. Their high sensitivity and moderate specificity warrant further prospective studies exploring whether their combined use could optimize performance.

Gender influence on manganese induced depression-like behavior and Mn and Fe deposition in different regions of CNS and excretory organs in intraperitoneally exposed rats.

Manganese (Mn) is an essential metal for mammals. It can modulate the action of endogenous substances, as neurotransmitters, but in excess also can trigger known neurotoxic effects. Many studies have been conducted assessing Mn neurotoxicity. However, Mn bioaccumulation in different brain tissues and behavior effects involving gender-specific studies are conflicted in the literature. Therefore, the aim of this work was to compare Mn effects, after 30days of intraperitoneal treatment, in male and female rats, submitted to forced swim and open field tests. After that, were evaluated Mn and Fe tissue levels in CNS, liver, and kidneys. Wistar rats were divided into saline, Mn 1mg/kg, Mn 5mg/kg, and imipramine (as forced swim control). Then, animals were euthanized by anesthesia overdose followed by decapitation and the collected tissue were striatum, hippocampus, brainstem, cortex, cerebellum, hepatic tissue, and renal tissue. Mn and Fe were determined by ICP-MS. There was a dose-dependent effect on accumulation of Mn in the cerebellum and brainstem to the dosage of 5mg/kg. In hippocampus there were bioaccumulation differences between gender and dose, and an increase of Fe in the groups exposed to Mn. Excess metals in the brain dissected has a strong influence on memory and learning processes and suggests pro-depressive effects, possibly triggered by the reduction of monoamines due to excessive metal bioaccumulation. It was concluded that, under this experimental design, Mn exposure cause metal deposition on dissected CNS, liver and kidney. There an effect at lower doses that was gender-dependent and males had more pronounced behavioral damage compared to females, although with increasing dose, females had an indication of motor damage.

Glucose solution is more effective in relieving pain in neonates than non-nutritive sucking: A randomized clinical trial.

BACKGROUND: Few studies have compared the analgesic effect of 25% glucose and non-nutritive sucking. We compared the analgesic effect of 25% glucose and non-nutritive sucking in newborns undergoing hepatitis B vaccination. Our hypothesis is that 25% glucose is more effective in relieving pain than non-nutritive sucking. METHODS: A randomized clinical trial with 78 healthy newborns was performed. Neonates were assigned randomly to receive 25% glucose (G25) and non-nutritive sucking (NNS). Pain was assessed using the Neonatal Infant Pain Scale (NIPS) before and during the immunization procedure. In addition, we evaluated various physiological parameters and crying time. RESULTS: Neonates who received 25% glucose registered lower NIPS scores than those from the NNS group [mean (SD), 3.3 (2.1) vs. 5.6 (1.6), p < 0.001]. The crying time was shorter among newborns in the G25 group than in the NNS and control groups. CONCLUSION: The use of 25% glucose before the vaccination procedure was more effective in relieving acute pain, with newborns in the G25 group registering scores two times lower on the NIPS scale. The clinical practice of administering 25% glucose is therefore a suggested nondrug measure for pain relief during painful procedures. SIGNIFICANCE: Neonates who received 25% glucose registered lower NIPS scores than those from the NNS group; the crying time was shorter among newborns in the G25 group than in the NNS and control groups; the use of 25% glucose before the vaccination procedure was more effective in relieving acute pain.

Genomic prediction for additive and dominance effects of censored traits in pigs.

Age at the time of slaughter is a commonly used trait in animal breeding programs. Since studying this trait involves incomplete observations (censoring), analysis can be performed using survival models or modified linear models, for example, by sampling censored data from truncated normal distributions. For genomic selection, the greatest genetic gains can be achieved by including non-additive genetic effects like dominance. Thus, censored traits with effects on both survival models have not yet been studied under a genomic selection approach. We aimed to predict genomic values using the Cox model with dominance effects and compare these results with the linear model with and without censoring. Linear models were fitted via the maximum likelihood method. For censored data, sampling through the truncated normal distribution was used, and the model was called the truncated normal linear via Gibbs sampling (TNL). We used an F2 pig population; the response variable was time (days) from birth to slaughter. Data were previously adjusted for fixed effects of sex and contemporary group. The model predictive ability was calculated based on correlation of predicted genomic values with adjusted phenotypic values. The results showed that both with and without censoring, there was high agreement between Cox and linear models in selection of individuals and markers. Despite including the dominance effect, there was no increase in predictive ability. This study showed, for the first time, the possibility of performing genomic prediction of traits with censored records while using the Cox survival model with additive and dominance effects.

Virulence and genetic diversity among isolates of Mycosphaerella fijiensis in two regions of Brazil.

Black sigatoka, caused by the fungus Mycosphaerella fijiensis (anamorphic stage: Paracercospora fijiensis), was first detected in Brazil in early 1998 in the Benjamin Constant and Tabatinga municipalities in the State of Amazonas, near to where the borders of Brazil, Colombia, and Peru converge. Understanding how cultivars react to the pathogen, and characterizing the genetic variability of isolates from two distant and distinct banana-producing regions, are important for determining the virulence of M. fijiensis. In the present study, the genetic diversity of 22 M. fijiensis isolates was assessed using simple sequence repeats (SSR) markers, and their virulence was determined following inoculation on three different banana tree cultivars. All 22 isolates caused symptoms of the disease in the Maçã and Prata Comum cultivars 45 days after inoculation, and at least two virulence groups were identified for the Maçã and Prata Comum cultivars. For the D'Angola cultivars, two virulence groups were observed only after 60 days post-inoculation, and three of the isolates were not virulent. Using SSR markers, the isolates from two different regions of Brazil were placed into two genetic groups, both genetically distant from the Mf 138 isolate collected in Leticia, Colombia. There was no evidence of correlation between the virulence groups and the genetic diversity groups. These results demonstrate variability in virulence between isolates as measured by the severity of black sigatoka in the analyzed cultivars.

Variation in cassava germplasm for tolerance to post-harvest physiological deterioration.

Tolerant varieties can effectively control post-harvest physiological deterioration (PPD) of cassava, although knowledge on the genetic variability and inheritance of this trait is needed. The objective of this study was to estimate genetic parameters and identify sources of tolerance to PPD and their stability in cassava accessions. Roots from 418 cassava accessions, grown in four independent experiments, were evaluated for PPD tolerance 0, 2, 5, and 10 days post-harvest. Data were transformed into area under the PPD-progress curve (AUP-PPD) to quantify tolerance. Genetic parameters, stability (Si), adaptability (Ai), and the joint analysis of stability and adaptability (Zi) were obtained via residual maximum likelihood (REML) and best linear unbiased prediction (BLUP) methods. Variance in the genotype (G) x environment (E) interaction and genotypic variance were important for PPD tolerance. Individual broad-sense heritability (hg(2)= 0.38 ± 0.04) and average heritability in accessions (hmg(2)= 0.52) showed high genetic control of PPD tolerance. Genotypic correlation of AUP-PPD in different experiments was of medium magnitude (ȓgA = 0.42), indicating significant G x E interaction. The predicted genotypic values o f G x E free of interaction (û + gi) showed high variation. Of the 30 accessions with high Zi, 19 were common to û + gi, Si, and Ai parameters. The genetic gain with selection of these 19 cassava accessions was -55.94, -466.86, -397.72, and -444.03% for û + gi, Si, Ai, and Zi, respectively, compared with the overall mean for each parameter. These results demonstrate the variability and potential of cassava germplasm to introduce PPD tolerance in commercial varieties.

Genomic selection for slaughter age in pigs using the Cox frailty model.

The aim of this study was to compare genomic selection methodologies using a linear mixed model and the Cox survival model. We used data from an F2 population of pigs, in which the response variable was the time in days from birth to the culling of the animal and the covariates were 238 markers [237 single nucleotide polymorphism (SNP) plus the halothane gene]. The data were corrected for fixed effects, and the accuracy of the method was determined based on the correlation of the ranks of predicted genomic breeding values (GBVs) in both models with the corrected phenotypic values. The analysis was repeated with a subset of SNP markers with largest absolute effects. The results were in agreement with the GBV prediction and the estimation of marker effects for both models for uncensored data and for normality. However, when considering censored data, the Cox model with a normal random effect (S1) was more appropriate. Since there was no agreement between the linear mixed model and the imputed data (L2) for the prediction of genomic values and the estimation of marker effects, the model S1 was considered superior as it took into account the latent variable and the censored data. Marker selection increased correlations between the ranks of predicted GBVs by the linear and Cox frailty models and the corrected phenotypic values, and 120 markers were required to increase the predictive ability for the characteristic analyzed.

Chronic stress associated with hypercaloric diet changes the hippocampal BDNF levels in male Wistar rats.

Chronic stress, whether associated with obesity or not, leads to different neuroendocrine and psychological changes. Obesity or being overweight has become one of the most serious worldwide public health problems. Additionally, it is related to a substantial increase in daily energy intake, which results in substituting nutritionally adequate meals for snacks. This metabolic disorder can lead to morbidity, mortality, and reduced quality of life. On the other hand, brain-derived neurotrophic factor (BDNF) is widely expressed in all brain regions, particularly in the hypothalamus, where it has important effects on neuroprotection, synaptic plasticity, mammalian food intake-behavior, and energy metabolism. BDNF is involved in many activities modulated by the hypothalamic-pituitary-adrenal (HPA) axis. Therefore, this study aims to evaluate the effect of obesity associated with chronic stress on the BDNF central levels of rats. Obesity was controlled by analyzing the animals' caloric intake and changes in body weight. As a stress parameter, we analyzed the relative adrenal gland weight. We found that exposure to chronic restraint stress during 12 weeks increases the adrenal gland weight, decreases the BDNF levels in the hippocampus and is associated with a decrease in the calorie and sucrose intake, characterizing anhedonia. These effects can be related stress, a phenomenon that induces depression-like behavior. On the other hand, the rats that received the hypercaloric diet had an increase in calorie intake and became obese, which was associated with a decrease in hypothalamus BDNF levels.

Classification of cassava genotypes based on qualitative and quantitative data.

We evaluated the genetic variation of cassava accessions based on qualitative (binomial and multicategorical) and quantitative traits (continuous). We characterized 95 accessions obtained from the Cassava Germplasm Bank of Embrapa Mandioca e Fruticultura; we evaluated these accessions for 13 continuous, 10 binary, and 25 multicategorical traits. First, we analyzed the accessions based only on quantitative traits; next, we conducted joint analysis (qualitative and quantitative traits) based on the Ward-MLM method, which performs clustering in two stages. According to the pseudo-F, pseudo-t2, and maximum likelihood criteria, we identified five and four groups based on quantitative trait and joint analysis, respectively. The smaller number of groups identified based on joint analysis may be related to the nature of the data. On the other hand, quantitative data are more subject to environmental effects in the phenotype expression; this results in the absence of genetic differences, thereby contributing to greater differentiation among accessions. For most of the accessions, the maximum probability of classification was >0.90, independent of the trait analyzed, indicating a good fit of the clustering method. Differences in clustering according to the type of data implied that analysis of quantitative and qualitative traits in cassava germplasm might explore different genomic regions. On the other hand, when joint analysis was used, the means and ranges of genetic distances were high, indicating that the Ward-MLM method is very useful for clustering genotypes when there are several phenotypic traits, such as in the case of genetic resources and breeding programs.

Genetic parameters and prediction of genotypic values for root quality traits in cassava using REML/BLUP.

The aim of this study was to estimate the genetic parameters and predict the genotypic values of root quality traits in cassava (Manihot esculenta Crantz) using restricted maximum likelihood (REML) and best linear unbiased prediction (BLUP). A total of 471 cassava accessions were evaluated over two years of cultivation. The evaluated traits included amylose content (AML), root dry matter (DMC), cyanogenic compounds (CyC), and starch yield (StYi). Estimates of the individual broad-sense heritability of AML were low (hg(2) = 0.07 ± 0.02), medium for StYi and DMC, and high for CyC. The heritability of AML was substantially improved based on mean of accessions (hm(2) = 0.28), indicating that some strategies such as increasing the number of repetitions can be used to increase the selective efficiency. In general, the observed genotypic values were very close to the predicted average of the improved population, most likely due to the high accuracy (>0.90), especially for DMC, CyC, and StYi. Gains via selection of the 30 best genotypes for each trait were 4.8 and 3.2% for an increase and decrease for AML, respectively, an increase of 10.75 and 74.62% for DMC for StYi, respectively, and a decrease of 89.60% for CyC in relation to the overall mean of the genotypic values. Genotypic correlations between the quality traits of the cassava roots collected were generally favorable, although they were low in magnitude. The REML/BLUP method was adequate for estimating genetic parameters and predicting the genotypic values, making it useful for cassava breeding.

Development of a cassava core collection based on single nucleotide polymorphism markers.

Single nucleotide polymorphism (SNP) markers were used in the largest cassava (Manihot esculenta Crantz) germplasm collection from Brazil to develop core collections based on the maximization strategy. Subsets with 61, 64, 84, 128, 256, and 384 cassava accessions were selected and named PoHEU, MST64, PoRAN, MST128, MST256, and MST384, respectively. All the 798 alleles identified by 402 SNP markers in the entire collection were captured in all core collections. Only small alterations in the diversity parameters were observed for the different core collections compared with the complete collection. Because of the optimal adjustment of the validation parameters representative of the complete collection, the absence of genotypes with high genetic similarity and the maximization of the genetic distances between accessions of the PoHEU core collection, which contained 4.7% of the accessions of the complete collection, maximized the genetic conservation of this important cassava collection. Furthermore, the development of this core collection will allow concentrated efforts toward future characterization and agronomic evaluation of accessions to maximize the diversity and genetic gains in cassava breeding programs.