Insertions of mitochondrial DNA into the nucleus—effects and role in cell evolution

We review the insertion of mitochondrial DNA (mtDNA) fragments into nuclear DNA (NUMTS) as a general and ongoing process that has occurred many times during genome evolution. Fragments of mtDNA are generated during the lifetime of organisms in both somatic and germinal cells, by the production of reactive oxygen species in the mitochondria. The fragments are inserted into the nucleus during the double-strand breaks repair via the non-homologous end-joining machinery, followed by genomic instability, giving rise to the high variability observed in NUMT patterns among species, populations, or genotypes. Some de novo produced mtDNA insertions show harmful effects, being involved in human diseases, carcinogenesis, and ageing. NUMT generation is a non-stop process overpassing the Mendelian transmission. This parasitic property ensures their survival even against their harmful effects. The accumulation of mtDNA fragments mainly at pericentromeric and subtelomeric regions is important to understand the transmission and integration of NUMTs into the genomes. The possible effect of female meiotic drive for mtDNA insertions at centromeres remains to be studied. In spite of the harmful feature of NUMTs, they are important in cell evolution, representing a major source of genomic variation

Is maize B chromosome preferential fertilization controlled by a single gene?

In previous work, genotypes for high and low B chromosome transmission rate were selected from a native race of maize. It was demonstrated that the B transmission is genetically controlled. The present work reports the fourth and fifth generations of selection and the F1 hybrids between the lines. The native B is characterized by a constant behaviour, with normal meiosis and nondisjunction in 100% of postmeiotic mitosis. It is concluded that genetic variation for B transmission between the selected lines is due to the preferential fertilization process. The F1 hybrids show intermediate B transmission rate between the lines. They are uniform, the variance of the selected character being one order of magnitude lower than that of the native population. In addition, 0B×2B and 2B×2B crosses were made to study the effect of the presence of B chromosomes in the female parent, resulting in non-significant differences. Several crosses were made both in Buenos Aires and in Madrid to compare the possible environmental effect, but significant differences were not found. Our results are consistent with the hypothesis of a single major gene controlling B transmission rate in maize, which acts in the egg cell at the haploid level during fertilization. It is also hypothesized that maize Bs use the normal maize fertilization process to promote their own transmission.Facultad de Ciencias Agrarias y Forestale

Is maize B chromosome preferential fertilization controlled by a single gene?

In previous work, genotypes for high and low B chromosome transmission rate were selected from a native race of maize. It was demonstrated that the B transmission is genetically controlled. The present work reports the fourth and fifth generations of selection and the F1 hybrids between the lines. The native B is characterized by a constant behaviour, with normal meiosis and nondisjunction in 100% of postmeiotic mitosis. It is concluded that genetic variation for B transmission between the selected lines is due to the preferential fertilization process. The F1 hybrids show intermediate B transmission rate between the lines. They are uniform, the variance of the selected character being one order of magnitude lower than that of the native population. In addition, 0B×2B and 2B×2B crosses were made to study the effect of the presence of B chromosomes in the female parent, resulting in non-significant differences. Several crosses were made both in Buenos Aires and in Madrid to compare the possible environmental effect, but significant differences were not found. Our results are consistent with the hypothesis of a single major gene controlling B transmission rate in maize, which acts in the egg cell at the haploid level during fertilization. It is also hypothesized that maize Bs use the normal maize fertilization process to promote their own transmission.Facultad de Ciencias Agrarias y Forestale

Comparison of univariate and multivariate drought indices based on satellite data for hydrological drought monitoring in the Southern ARA, Mozambique

[EN] Drought is a natural phenomenon that affects socio-economic and environmental systems, so monitoring it is crucial to minimize its impacts. In Mozambique, in southern Africa, 70% of the population depends on agriculture for subsistence, and water for this activity is mostly extracted directly from rivers. In this paper we have compared several univariate and multivariate drought indices calculated with variables from satellite databases to define one that best fits the hydrological drought conditions in the watersheds of the Southern ARA of Mozambique. The hydrological conditions were defined using the Standardized Runoff Index 3-month cumulative (SRI-3). Using cross-correlations and linear and non-linear regression models, it was found that the Standardized Precipitation Index 3-month cumulative (SPI-3) could be used to monitor hydrological droughts in this region in (near) real time.[ES] La sequía es un fenómeno natural que afecta a los sistemas socioeconómicos y medioambientales por lo que su monitorización es clave para minimizar sus impactos. En Mozambique, en el sur de África el 70% de la población depende la agricultura para sobrevivir, y el agua para esta actividad se extrae mayoritariamente directo de los ríos. En este trabajo hemos comparado varios índices de sequía univariables y multivariables calculados con variables provenientes de bases de datos satelitales para definir uno que mejor se ajuste a las condiciones de sequía hidrológica en las cuencas hidrográficas del ARA Sur de Mozambique. Las condiciones hidrológicas se definieron con el Índice Estandarizado de Escorrentía acumulado 3 meses (SRI-3). Mediante relaciones cruzadas y modelos de regresión lineales y no lineales se encontró que el Índice Estandarizado de Precipitación acumulado 3 meses (SPI-3) podría usarse para monitorizar las sequías hidrológicas en esta región en tiempo (casi) real.Este trabajo fue realizado en el marco del proyecto AquaMoz-Secara Fase 2, financiado por Augas de Galicia y la Dirección Xeral de Relacións Exteriores y con la Unión Europea de la Xunta de Galicia.Araneda-Cabrera, RJ.; Bermúdez, M.; Puertas, J.; Penas, V. (2022). Comparación de índices de sequía univariables y multivariables basados en datos satelitales para la monitorización de sequías hidrológicas en el ARA Sur, Mozambique. Ingeniería del Agua. 26(3):217-229. https://doi.org/10.4995/ia.2022.1803721722926

Rhizobial Volatiles: Potential New Players in the Complex Interkingdom Signaling With Legumes

Bacteria release a wide range of volatile compounds that play important roles in intermicrobial and interkingdom communication. Volatile metabolites emitted by rhizobacteria can promote plant growth and increase plant resistance to both biotic and abiotic stresses. Rhizobia establish beneficial nitrogen-fixing symbiosis with legume plants in a process starting with a chemical dialog in the rhizosphere involving various diffusible compounds. Despite being one of the most studied plant-interacting microorganisms, very little is known about volatile compounds produced by rhizobia and their biological/ecological role. Evidence indicates that plants can perceive and respond to volatiles emitted by rhizobia. In this perspective, we present recent data that open the possibility that rhizobial volatile compounds have a role in symbiotic interactions with legumes and discuss future directions that could shed light onto this area of investigation

Two-step ATP-driven opening of cohesin head.

The cohesin ring is a protein complex composed of four core subunits: Smc1A, Smc3, Rad21 and Stag1/2. It is involved in chromosome segregation, DNA repair, chromatin organization and transcription regulation. Opening of the ring occurs at the “head” structure, formed of the ATPase domains of Smc1A and Smc3 and Rad21. We investigate the mechanisms of the cohesin ring opening using techniques of free molecular dynamics (MD), steered MD and quantum mechanics/molecular mechanics MD (QM/MM MD). The study allows the thorough analysis of the opening events at the atomic scale: i) ATP hydrolysis at the Smc1A site, evaluating the role of the carboxy-terminal domain of Rad21 in the process; ii) the activation of the Smc3 site potentially mediated by the movement of specific amino acids; and iii) opening of the head domains after the two ATP hydrolysis events. Our study suggests that the cohesin ring opening is triggered by a sequential activation of the ATP sites in which ATP hydrolysis at the Smc1A site induces ATPase activity at the Smc3 site. Our analysis also provides an explanation for the effect of pathogenic variants related to cohesinopathies and cancer.post-print4709 K

On the Metric Dimension of Cartesian Products of Graphs

A set S of vertices in a graph G resolves G if every vertex is uniquely determined by its vector of distances to the vertices in S. The metric dimension of G is the minimum cardinality of a resolving set of G. This paper studies the metric dimension of cartesian products G*H. We prove that the metric dimension of G*G is tied in a strong sense to the minimum order of a so-called doubly resolving set in G. Using bounds on the order of doubly resolving sets, we establish bounds on G*H for many examples of G and H. One of our main results is a family of graphs G with bounded metric dimension for which the metric dimension of G*G is unbounded

Molecular Basis of the Schuurs–Hoeijmakers Syndrome: What We Know about the Gene and the PACS-1 Protein and Novel Therapeutic Approaches

The Schuurs–Hoeijmakers syndrome (SHMS) or PACS1 Neurodevelopment Disorder (PACS1-NDD) is a rare autosomal dominant disease caused by mutations in the PACS1 gene. To date, only 87 patients have been reported and, surprisingly, most of them carry the same variant (c.607C>T; p.R203W). The most relevant clinical features of the syndrome include neurodevelopment delay, seizures or a recognizable facial phenotype. Moreover, some of these characteristics overlap with other syndromes, such as the PACS2 or Wdr37 syndromes. The encoded protein phosphofurin acid cluster sorting 1 (PACS-1) is able to bind to different client proteins and direct them to their subcellular final locations. Therefore, although its main function is protein trafficking, it could perform other roles related to its client proteins. In patients with PACS1-NDD, a gain-of-function or a dominant negative mechanism for the mutated protein has been suggested. This, together with the fact that most of the patients carry the same genetic variant, makes it a good candidate for novel therapeutic approaches directed to decreasing the toxic effect of the mutated protein. Some of these strategies include the use of antisense oligonucleotides (ASOs) or targeting of its client proteins

Molecular characterization of TC964, a novel antigenic protein from trypanosoma cruzi

The Tc964 protein was initially identified by its presence in the interactome associated with the LYT1 mRNAs, which code for a virulence factor of Trypanosoma cruzi. Tc964 is annotated in the T. cruzi genome as a hypothetical protein. According to phylogenetic analysis, the protein is conserved in the different genera of the Trypanosomatidae family; however, recognizable orthologues were not identified in other groups of organisms. Therefore, as a first step, an in-depth molecular characterization of the Tc946 protein was carried out. Based on structural predictions and molecular dynamics studies, the Tc964 protein would belong to a particular class of GTPases. Subcellular fractionation analysis indicated that Tc964 is a nucleocytoplasmic protein. Additionally, the protein was expressed as a recombinant protein in order to analyze its antigenicity with sera from Chagas disease (CD) patients. Tc964 was found to be antigenic, and B-cell epitopes were mapped by the use of synthetic peptides. In parallel, the Leishmania major homologue (Lm964) was also expressed as recombinant protein and used for a preliminary evaluation of antigen cross-reactivity in CD patients. Interestingly, Tc964 was recognized by sera from Chronic CD (CCD) patients at different stages of disease severity, but no reactivity against this protein was observed when sera from Colombian patients with cutaneous leishmaniasis were analyzed. Therefore, Tc964 would be adequate for CD diagnosis in areas where both infections (CD and leishmaniasis) coexist, even though additional assays using larger collections of sera are needed in order to confirm its usefulness for differential serodiagnosisThis research was funded by Ministerio de Ciencia,Tecnología e Innovación (Minciencias) and Pontificia Universidad Javeriana, research project ID PPTA 120356933228 granted to C.J.P. The article publication was funded by the Vicerrectoría de Investigación from the Pontificia Universidad Javeriana, code 120813F0401200. The Network of Tropical Diseases Research RICET (RD16/0027/0008, Instituto de Salud Carlos III and co-funded by FEDER) to J.M.R., and grants from the Spanish Ministerio de Ciencia, Innovación y Universidades/Agencia Estatal de Investigación RTC-2017-6494-1 and RTI2018-094434-B-I00 (MCIU/AEI/FEDER, UE) to P.G.-P., E.R.-M and E.R.R. were supported by Minciencias convocatoria doctorados nacionales 647-2014 and convocatoria jóvenes investigadores e innovadores 706-2015, respectivel

Is maize B chromosome preferential fertilization controlled by a single gene?

In previous work, genotypes for high and low B chromosome transmission rate were selected from a native race of maize. It was demonstrated that the B transmission is genetically controlled. The present work reports the fourth and fifth generations of selection and the F1 hybrids between the lines. The native B is characterized by a constant behaviour, with normal meiosis and nondisjunction in 100% of postmeiotic mitosis. It is concluded that genetic variation for B transmission between the selected lines is due to the preferential fertilization process. The F1 hybrids show intermediate B transmission rate between the lines. They are uniform, the variance of the selected character being one order of magnitude lower than that of the native population. In addition, 0B×2B and 2B×2B crosses were made to study the effect of the presence of B chromosomes in the female parent, resulting in non-significant differences. Several crosses were made both in Buenos Aires and in Madrid to compare the possible environmental effect, but significant differences were not found. Our results are consistent with the hypothesis of a single major gene controlling B transmission rate in maize, which acts in the egg cell at the haploid level during fertilization. It is also hypothesized that maize Bs use the normal maize fertilization process to promote their own transmission.Facultad de Ciencias Agrarias y Forestale