Expression of Arabidopsis Bax Inhibitor‐1 in transgenic sugarcane confers drought tolerance

The sustainability of global crop production is critically dependent on improving tolerance of crop plants to various types of environmental stress. Thus, identification of genes that confer stress tolerance in crops has become a top priority especially in view of expected changes in global climatic patterns. Drought stress is one of the abiotic stresses that can result in dramatic loss of crop productivity. In this work, we show that transgenic expression of a highly conserved cell death suppressor, Bax Inhibitor‐1 from Arabidopsis thaliana (AtBI‐1), can confer increased tolerance of sugarcane plants to long‐term (>20 days) water stress conditions. This robust trait is correlated with an increased tolerance of the transgenic sugarcane plants, especially in the roots, to induction of endoplasmic reticulum (ER) stress by the protein glycosylation inhibitor tunicamycin. Our findings suggest that suppression of ER stress in C₄ grasses, which include important crops such as sorghum and maize, can be an effective means of conferring improved tolerance to long‐term water deficit. This result could potentially lead to improved resilience and yield of major crops in the world.     

The C-terminal domain of TPX2 is made of alpha-helical tandem repeats

Background

TPX2 (Targeting Protein for Xklp2) is essential for spindle assembly, activation of the mitotic kinase Aurora A and for triggering microtubule nucleation. Homologs of TPX2 in Chordata and plants were previously identified. Currently, proteins of the TPX2 family have little structural information and only small parts are covered by defined protein domains.

Methods

We have used computational sequence analyses and structural predictions of proteins of the TPX2 family, supported with Circular Dichroism (CD) measurements.

Results

Here, we report our finding that the C-terminal domain of TPX2, which is responsible of its microtubule nucleation capacity and is conserved in all members of the family, is actually formed by tandem repeats, covering well above 2/3 of the protein. We propose that this region forms a flexible solenoid involved in protein-protein interactions. Structural prediction and molecular modeling, combined with Circular Dichroism (CD) measurements reveal a predominant alpha-helical content. Furthermore, we identify full length homologs in fungi and shorter homologs with a different domain organization in diptera (including a paralogous expansion in Drosophila).

Conclusions

Our results, represent the first computational and biophysical analysis of the TPX2 proteins family and help understand the structure and evolution of this conserved protein family to direct future structural studies.

     

Evaluation of metabolomics profiles of grain from maize hybrids derived from near-isogenic GM positive and negative segregant inbreds demonstrates that observed differences cannot be attributed unequivocally to the GM trait

Introduction

Past studies on plant metabolomes have highlighted the influence of growing environments and varietal differences in variation of levels of metabolites yet there remains continued interest in evaluating the effect of genetic modification (GM).

Objectives

Here we test the hypothesis that metabolomics differences in grain from maize hybrids derived from a series of GM (NK603, herbicide tolerance) inbreds and corresponding negative segregants can arise from residual genetic variation associated with backcrossing and that the effect of insertion of the GM trait is negligible.

Methods

Four NK603-positive and negative segregant inbred males were crossed with two different females (testers). The resultant hybrids, as well as conventional comparator hybrids, were then grown at three replicated field sites in Illinois, Minnesota, and Nebraska during the 2013 season. Metabolomics data acquisition using gas chromatography–time of flight-mass spectrometry (GC–TOF-MS) allowed the measurement of 367 unique metabolite features in harvested grain, of which 153 were identified with small molecule standards. Multivariate analyses of these data included multi-block principal component analysis and ANOVA-simultaneous component analysis. Univariate analyses of all 153 identified metabolites was conducted based on significance testing (α = 0.05), effect size evaluation (assessing magnitudes of differences), and variance component analysis.

Results

Results demonstrated that the largest effects on metabolomic variation were associated with different growing locations and the female tester. They further demonstrated that differences observed between GM and non-GM comparators, even in stringent tests utilizing near-isogenic positive and negative segregants, can simply reflect minor genomic differences associated with conventional back-crossing practices.

Conclusion

The effect of GM on metabolomics variation was determined to be negligible and supports that there is no scientific rationale for prioritizing GM as a source of variation.

     

Cretaceous angiosperm pollen from the Kachaike Formation,south-western Santa Cruz Province,Argentina

Thirty-three angiosperm pollen species are here reported from mid-Cretaceous deposits of the Kachaike Formation, Austral Basin, southern Argentina. Clavatipollenites is the most abundant angiosperm genus, with six well-defined morphological groups recognised on the basis of their reticulum morphology and sculpture. Pollen of eudicots are scarce, represented by tricolpate (Psilatricolpites spp. and Tricolpites spp.), tricolporoidate and tricolporate morphotypes (Dryadopollis spp.). Increasing complexity in the aperture structure is seen throughout the sequence; tricolpate and tricolporoidate forms are recorded in almost all samples, while tricolporate pollen grains are restricted to the middle and upper levels of the unit. The high species richness and abundance of monocolpate-ulcerate angiosperm related to monocots or magnoliids sensu lato recorded in the unit is comparable to that previously recognised in other assemblages from the early and middle Albian of the southern (e.g. Australia) and northern hemispheres (e.g. Western Portuguese basin, Europe). The recorded increase in the number of angiosperm species towards the middle and upper parts of the Kachaike Formation, with the presence of monocolpate, tricolpate, tricolporoidate and tricolporate pollen, suggests an early-early middle Albian age for these parts of the unit, in agreement with the early Albian age proposed for its basal levels on the basis of dinoflagellates.     

Characterizing symbiont inheritance during host–microbiota evolution: Application to the great apes gut microbiota

Microbiota play a central role in the functioning of multicellular life, yet understanding their inheritance during host evolutionary history remains an important challenge. Symbiotic microorganisms are either acquired from the environment during the life of the host (i.e. environmental acquisition), transmitted across generations with a faithful association with their hosts (i.e. strict vertical transmission), or transmitted with occasional host switches (i.e. vertical transmission with horizontal switches). These different modes of inheritance affect microbes’ diversification, which at the two extremes can be independent from that of their associated host or follow host diversification. The few existing quantitative tools for investigating the inheritance of symbiotic organisms rely on cophylogenetic approaches, which require knowledge of both host and symbiont phylogenies, and are therefore often not well adapted to DNA metabarcoding microbial data. Here, we develop a model‐based framework for identifying vertically transmitted microbial taxa. We consider a model for the evolution of microbial sequences on a fixed host phylogeny that includes vertical transmission and horizontal host switches. This model allows estimating the number of host switches and testing for strict vertical transmission and independent evolution. We test our approach using simulations. Finally, we illustrate our framework on gut microbiota high‐throughput sequencing data of the family Hominidae and identify several microbial taxonomic units, including fibrolytic bacteria involved in carbohydrate digestion, that tend to be vertically transmitted.     

Phylogeographical and cross‐species transmission dynamics of SAT1 and SAT2 foot‐and‐mouth disease virus in Eastern Africa

Understanding the dynamics of foot‐and‐mouth disease virus (FMDV), an endemic and economically constraining disease, is critical in designing control programmes in Africa. This study investigates the evolutionary epidemiology of SAT1 and SAT2 FMDV in Eastern Africa, as well as between cattle and wild African buffalo. Bayesian phylodynamic models were used to analyse SAT1 and SAT2 VP1 gene segments collected between 1975 and 2016, focusing on the SAT1 and SAT2 viruses currently circulating in Eastern Africa. The root state posterior probabilities inferred from our analyses suggest Zimbabwe as the ancestral location for SAT1 currently circulating in Eastern Africa (p = 0.67). For the SAT2 clade, Kenya is inferred to be the ancestral location for introduction of the virus into other countries in Eastern Africa (p = 0.72). Salient (Bayes factor >10) viral dispersal routes were inferred from Tanzania to Kenya, and from Kenya to Uganda for SAT1 and SAT2, respectively. Results suggest that cattle are the source of the SAT1 and SAT2 clades currently circulating in Eastern Africa. In addition, our results suggest that the majority of SAT1 and SAT2 in livestock come from other livestock rather than wildlife, with limited evidence that buffalo serve as reservoirs for cattle. Insights from the present study highlight the role of cattle movements and anthropogenic activities in shaping the evolutionary history of SAT1 and SAT2 in Eastern Africa. While the results may be affected by inherent limitations of imperfect surveillance, our analysis elucidates the dynamics between host species in this region, which is key to guiding disease intervention activities.     

Extender Supplementation with Antioxidants Selected after the Evaluation of Sperm Susceptibility to Oxidative Challenges in Goats

This study aimed to detect the most deleterious ROS for goat sperm and then supplemented the extender with a proper antioxidant. For this, 12 adult goats (aged 1–7) were used. Fresh samples were submitted to challenge with different ROS (superoxide anion, hydrogen peroxide, and hydroxyl radical) and malondialdehyde (MDA—toxic product of lipid peroxidation). After experiment 1, sperms were cryopreserved in extenders supplemented to glutathione peroxidase (Control: 0?UI/mL; GPx1: 1?UI/mL; GPx5: 5?UI/mL, and GPx10: 10?UI/mL) and catalase (Control: 0?UI/mL; CAT60: 60?UI/mL; CAT120: 120?UI/mL, and CAT240: 240?UI/mL). Each sample was evaluated by motility, plasma membrane integrity (eosin/nigrosin), acrosome integrity (fast green/rose bengal), sperm morphology, assay of the sperm chromatin structure, mitochondrial activity (3,3-diaminobenzidine), and measurement of lipid peroxidation (thiobarbituric acid reactive substances [TBARS]). It was possible to observe a mitochondrial dysfunction (DAB—Class IV) and low membrane integrity after hydrogen peroxide action. However, the high rates of TBARS were observed on hydroxyl radical. CAT240 presents the lower percentage of plasma membrane integrity. It was possible to attest that hydrogen peroxide and hydroxyl radical are the more harmful for goat sperm. Antioxidant therapy must be improving perhaps using combination between antioxidants.