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Biology subjects

Santos, M. F.

Publications and source records attributed to Santos, M. F..

6 recordsLinked to original sources

Harnessing Interpretable Deep Learning to Predict Meropenem Resistance in Klebsiella pneumoniae

Antimicrobial resistance constitutes an escalating global health threat, complicating therapeutic management and increasing morbidity and mortality. Deep learning approaches have emerged as promising tools for bacterial profiling based on omics data, particularly for predicting antimicrobial susceptibility from genomic information. This task relies on identifying genomic signatures associated with resistance mechanisms. Here, DeepMDC is introduced as a deep learning architecture designed for bacterial profiling using whole-genome data. Given that precise annotation at the gene or mutation level is often costly and ambiguous, phenotypic classification is formulated as a Multiple Instance Learning (MIL) problem, in which each genome is represented as a bag of instances with a single associated label. The core of DeepMDC is a Modern Hopfield Network that processes all open reading frames (ORFs), including small ones, derived from genomic data. A key feature of the architecture is its interpretability, enabled by attention mechanisms that facilitate biological insight and hypothesis generation. The model was evaluated against Klebsiella pneumoniae and four clinically relevant antibiotics (meropenem, cefepime, ceftazidime, and gentamicin), achieving strong performance in several metrics. Notably, genes associated with resistance consistently received high attention scores during inference, which validates the architecture and eventually may generate new hypotheses.

systems biology↗

4-Nitrobenzoate inhibits 4-hydroxybenzoate polyprenyltransferase in malaria parasites and enhances atovaquone efficacy

Ubiquinone (UQ) is a critical component of the electron transport chain in Plasmodium falciparum, the etiological agent of human malaria. The first step in UQ biosynthesis is the condensation of 4-hydroxybenzoate (4-HB) and an isoprenic chain by the enzyme 4-hydroxybenzoate polyprenyltransferase (4-HPT; COQ2 gene). Atovaquone (AV), an antimalarial drug, competes with ubiquinol (UQH2) for binding to the mitochondrial bc1 complex, preventing the redox recycling of UQ. In clinical practice, AV is combined with proguanil, a dehydrofolate reductase inhibitor, in a single formulation. However, parasitic resistance to this combination has been demonstrated, indicating the need for new pharmacological combinations to potentiate AV. Previously, 4-nitrobenzoate (4-NB) demonstrated the ability to inhibit UQ biosynthesis in P. falciparum parasites as well as potentiate AV efficacy in vitro. However, both its pharmacodynamics and whether this potentiation could be useful in vivo remained obscure. Here we show that 4-NB enhances AV antiplasmodial efficacy to kill parasites, increases its selectivity compared with animal cells, and preserves proguanil efficacy. 4-NB specifically inhibited the 4-HPT enzymatic activity in mutant strains of Saccharomyces cerevisiae complemented with PfCOQ2. Finally, 4-NB also improved AV antimalarial efficacy in mice infected with Plasmodium berghei parasites. Finally, work with various 4-HB analogs delineated the chemical requirements to potentiate AV activity. These findings clarify the importance of UQ biosynthesis for malaria parasites and suggest that PfCOQ2 could be a therapeutic target to enhance the efficacy of AV.

microbiology↗

Assessing genotype adaptability and stability in perennial forage breeding trials using random regression models for longitudinal dry matter yield data

Genotype selection for dry matter yield (DMY) in perennial forage species is based on repeated measures over time. Repeated measurements in forage breeding trials generate longitudinal datasets that must be properly analyzed giving a useful interpretation in the genotype selection process. In this study, we have presented a random regression (RRM) approach for selecting genotypes based on longitudinal DMY data generated from ten breeding trials and three perennial species, alfalfa (Medicago sativa L.), guineagrass (Megathyrsus maximus), and brachiaria (Urochloa spp.). We also proposed the estimation of adaptability based on the area under the curve and stability based on the curve coefficient of variation. Our results showed that RRM always approximated the (co)variance structure into an autoregressive pattern. Furthermore, RRM can offer useful information about longitudinal data in forage breeding trials, where the breeder can select genotypes based on their seasonality by interpreting reaction norms. Therefore, we recommend using RRM for longitudinal traits in breeding trials for perennial species.

genetics↗

A joint learning approach for genomic prediction in polyploid grasses

Poaceae, among the most abundant plant families, includes many economically important polyploid species, such as forage grasses and sugarcane (Saccharum spp.). These species have elevated genomic complexities and limited genetic resources, hindering the application of marker-assisted selection strategies. Currently, the most promising approach for increasing genetic gains in plant breeding is genomic selection. However, due to the polyploidy nature of these polyploid species, more accurate models for incorporating genomic selection into breeding schemes are needed. This study aims to develop a machine learning method by using a joint learning approach to predict complex traits from genotypic data. Biparental populations of sugarcane and two species of forage grasses (Urochloa decumbens, Megathyrsus maximus) were genotyped, and several quantitative traits were measured. High-quality markers were used to predict several traits in different cross-validation scenarios. By combining classification and regression strategies, we developed a predictive system with promising results. Compared with traditional genomic prediction methods, the proposed strategy achieved accuracy improvements exceeding 50%. Our results suggest that the developed methodology could be implemented in breeding programs, helping reduce breeding cycles and increase genetic gains.

bioinformatics↗

An Automated SNP-Based Approach for Contaminant Identification in Biparental Polyploid Populations of Tropical Forage Grasses

Artificial hybridization plays a fundamental role in plant breeding programs since it generates new genotypic combinations that can result in desirable phenotypes. Depending on the species and mode of reproduction, controlled crosses may be challenging, and contaminating individuals can be introduced accidentally. In this context, the identification of such contaminants is important to avoid compromising further selection cycles, as well as genetic and genomic studies. The main objective of this work was to propose an automated multivariate methodology for the detection and classification of putative contaminants, including apomictic clones, self-fertilized individuals, half-siblings and full contaminants, in biparental polyploid progenies of tropical forage grasses. We established a pipeline to identify contaminants in genotyping-by-sequencing (GBS) data encoded as allele dosages of single nucleotide polymorphism (SNP) markers by integrating principal component analysis (PCA), genotypic analysis (GA) measures based on Mendelian segregation and clustering analysis (CA). The combination of these methods allowed the correct identification of all contaminants in all simulated progenies and the detection of putative contaminants in three real progenies of tropical forage grasses, providing an easy and promising methodology for the identification of contaminants in biparental progenies of tetraploid and hexaploid species. The proposed pipeline was made available through the polyCID Shiny app and can be easily coupled with traditional genetic approaches, such as linkage map construction, thereby increasing the efficiency of breeding programs.

genomics↗

High-resolution Linkage Map with Allele Dosage Allows the Identification of an Apomixis Region and Complex Traits in Guinea Grass (Megathyrsus maximus)

Forage grasses are mainly used in animal feed to fatten cattle and dairy herds. Among tropical forage crops that reproduce by seeds, guinea grass (Megathyrsus maximus) is considered one of the most productive. This species has several genomic complexities, such as autotetraploidy and apomixis, due to the process of domestication. Consequently, approaches that relate phenotypic and genotypic data are incipient. In this context, we built a linkage map with allele dosage and generated novel information about the genetic architecture of traits that are important for the breeding of M. maximus. From a full-sib progeny, a linkage map containing 858 single nucleotide polymorphism (SNP) markers with allele dosage information expected for an autotetraploid was obtained. The high genetic variability of the progeny allowed us to map ten quantitative trait loci (QTLs) related to agronomic traits, such as regrowth capacity and total dry matter, and 36 QTLs related to nutritional quality, which were distributed among all homology groups (HGs). Various overlapping regions associated with the quantitative traits suggested QTL hotspots. In addition, we were able to map one locus that controls apospory (apo-locus) in HG II. A total of 55 different gene families involved in cellular metabolism and plant growth were identified from markers adjacent to the QTLs and apomixis locus by using the Panicum virgatum genome as a reference in comparisons with the genomes of Arabidopsis thaliana and Oryza sativa. Our results provide a better understanding of the genetic basis of reproduction by apomixis and traits important for breeding programs that considerably influence animal productivity as well as the quality of meat and milk.

plant biology↗