Growth kinetics rather than stress accelerate telomere shortening in cultures of human diploid fibroblasts in oxidative stress-induced premature senescence

WI-38 human diploid fibroblasts underwent accelerated telomere shortening (490 bp/stress) and growth arrest after exposure to four subcytotoxic 100 microM tert-butylhydroperoxide (t-BHP) stresses, with a stress at every two population doublings (PD). After subcytotoxic 160 microM H2O2 stress or five repeated 30 microM t-BHP stresses along the same PD, respectively a 322 +/- 55 and 380 +/- 129 bp telomere shortening was observed only during the first PD after stress. The percentage of cells resuming proliferation after stress suggests this telomere shortening is due to the number of cell divisions accomplished to reach confluence during the first PD after stress.     

A genetics‐based approach confirms immune associations with life history across multiple populations of an aquatic vertebrate (Gasterosteus aculeatus)

Understanding how wild immune variation covaries with other traits can reveal how costs and trade‐offs shape immune evolution in the wild. Divergent life history strategies may increase or alleviate immune costs, helping shape immune variation in a consistent, testable way. Contrasting hypotheses suggest that shorter life histories may alleviate costs by offsetting them against increased mortality, or increase the effect of costs if immune responses are traded off against development or reproduction. We investigated the evolutionary relationship between life history and immune responses within an island radiation of three‐spined stickleback, with discrete populations of varying life histories and parasitism. We sampled two short‐lived, two long‐lived and an anadromous population using qPCR to quantify current immune profile and RAD‐seq data to study the distribution of immune variants within our assay genes and across the genome. Short‐lived populations exhibited significantly increased expression of all assay genes, which was accompanied by a strong association with population‐level variation in local alleles and divergence in a gene that may be involved in complement pathways. In addition, divergence around the eda gene in anadromous fish is likely associated with increased inflammation. A wider analysis of 15 populations across the island revealed that immune genes across the genome show evidence of having diverged alongside life history strategies. Parasitism and reproductive investment were also important sources of variation for expression, highlighting the caution required when assaying immune responses in the wild. These results provide strong, gene‐based support for current hypotheses linking life history and immune variation across multiple populations of a vertebrate model.     

Association Mapping Provides Insights into the Origin and the Fine Structure of the Sorghum Aluminum Tolerance Locus,AltSB

Root damage caused by aluminum (Al) toxicity is a major cause of grain yield reduction on acid soils, which are prevalent in tropical and subtropical regions of the world where food security is most tenuous. In sorghum, Al tolerance is conferred by SbMATE, an Al-activated root citrate efflux transporter that underlies the major Al tolerance locus, Alt_SB, on sorghum chromosome 3. We used association mapping to gain insights into the origin and evolution of Al tolerance in sorghum and to detect functional variants amenable to allele mining applications. Linkage disequilibrium across the Alt_SB locus decreased much faster than in previous reports in sorghum, and reached basal levels at approximately 1000 bp. Accordingly, intra-locus recombination events were found to be extensive. SNPs and indels highly associated with Al tolerance showed a narrow frequency range, between 0.06 and 0.1, suggesting a rather recent origin of Al tolerance mutations within Alt_SB. A haplotype network analysis suggested a single geographic and racial origin of causative mutations in primordial guinea domesticates in West Africa. Al tolerance assessment in accessions harboring recombinant haplotypes suggests that causative polymorphisms are localized to a ∼6 kb region including intronic polymorphisms and a transposon (MITE) insertion, whose size variation has been shown to be positively correlated with Al tolerance. The SNP with the strongest association signal, located in the second SbMATE intron, recovers 9 of the 14 highly Al tolerant accessions and 80% of all the Al tolerant and intermediately tolerant accessions in the association panel. Our results also demonstrate the pivotal importance of knowledge on the origin and evolution of Al tolerance mutations in molecular breeding applications. Allele mining strategies based on associated loci are expected to lead to the efficient identification, in diverse sorghum germplasm, of Al tolerant accessions able maintain grain yields under Al toxicity.     

How a microbial drug transporter became essential for crop cultivation on acid soils: aluminium tolerance conferred by the multidrug and toxic compound extrusion (MATE) family

Background

Aluminium (Al) toxicity is a major agricultural constraint for crop cultivation on acid soils, which comprise a large portion of the world''s arable land. One of the most widely accepted mechanisms of Al tolerance in plants is based on Al-activated organic acid release into the rhizosphere, with organic acids forming stable, non-toxic complexes with Al. This mechanism has recently been validated by the isolation of bona-fide Al-tolerance genes in crop species, which encode membrane transporters that mediate Al-activated organic acid release leading to Al exclusion from root apices. In crop species such as sorghum and barley, members in the multidrug and toxic compound extrusion (MATE) family underlie Al tolerance by a mechanism based on Al-activated citrate release.

Scope and Conclusions

The study of Al tolerance in plants as conferred by MATE family members is in its infancy. Therefore, much is yet to be discovered about the functional diversity and evolutionary dynamics that led MATE proteins to acquire transport properties conducive to Al tolerance in plants. In this paper we review the major characteristics of transporters in the MATE family and will relate this knowledge to Al tolerance in plants. The MATE family is clearly extremely flexible with respect to substrate specificity, which raises the possibility that Al tolerance as encoded by MATE proteins may not be restricted to Al-activated citrate release in plant species. There are also indications that regulatory loci may be of pivotal importance to fully explore the potential for Al-tolerance improvement based on MATE genes.     

Baseline susceptibility of western corn rootworm (Coleoptera: Chrysomelidae) to clothianidin

Abstract:  Western corn rootworm, Diabrotica virgifera virgifera LeConte, neonate susceptibility to clothianidin, a contact and systemic neonicotinoid insecticide, was determined from both laboratory and field-collected populations. Neonates were exposed to filter paper treated with increasing clothianidin concentrations and mortality was evaluated after 24 h. Additionally, two populations were exposed to an artificial diet which was surface treated with clothianidin. Although larvae were five- to six-fold more sensitive to treated diet, results with treated filter paper were more reliable in terms of control mortality and required much less manipulation of rootworm larvae. Therefore, initial baseline comparisons were conducted using the filter paper assays. The variation among populations exposed to treated filter paper was generally low, 4.4-fold among laboratory populations tested; however, there was a 14.5-fold difference in susceptibility among all populations tested. In general, clothianidin was very toxic to rootworm neonates, with LC₅₀ values ranging from 1.5 to 21.9 ng/cm². These results indicate the practicability and sensitivity of the paper filter disc assay to establish baseline susceptibility levels, which is an essential first step in resistance management. A baseline response provides a reference for tracking shifts in susceptibility following commercialization of a control agent so that early changes in susceptibility can be detected.     

Increased Gastric IL-1β Concentration and Iron Deficiency Parameters in H. pylori Infected Children

Association between H. pylori infection, iron deficiency and iron deficiency anaemia has been described, but the mechanisms involved have not been established. We hypothesized that in H. pylori infected children increased gastric concentrations of IL-1β and/or TNF-α, both potent inhibitors of gastric acid secretion that is essential for iron absorption, are predictors for low blood concentrations of ferritin and haemoglobin, markers of early depletion of iron stores and anaemia, respectively. We evaluated 125 children undergoing endoscopy to clarify the origin of gastrointestinal symptoms. Gastric specimens were obtained for H. pylori status and cytokine evaluation and blood samples for determination of iron deficiency/iron deficiency anaemia parameters and IL1 cluster and TNFA polymorphisms that are associated with increased cytokine secretions. Higher IL-1β and TNF-α gastric concentrations were observed in H. pylori-positive (n = 47) than in -negative (n = 78) children. Multiple linear regression models revealed gastric IL-1β, but not TNF-α, as a significant predictor of low ferritin and haemoglobin concentrations; results were reproduced in young children in whom IL1RN polymorphic genotypes associated with higher gastric IL-1β expression and lower blood ferritin and haemoglobin concentrations. In conclusion, high gastric levels of IL-1β can be the link between H. pylori infection and iron deficiency/iron deficiency anaemia in childhood.     

The effects of monensin on Golgi complex of adrenal cortex and steroidogenesis.

The ultrastructural and biochemical changes produced by monensin on zona fasciculata cells of the rat adrenal cortex are described. In this study we used adrenal cells in culture, adrenal slices and the intact animal. Monensin (1 microM) was added to the culture medium containing the cells, and to the incubation medium containing the adrenal slices, and was injected intravenously to the intact animal (0.65 mg/kg body weight). The ultrastructural alterations were similar in the three experimental conditions, and consisted of Golgi complex disorganization with dilated cisternae or large smooth vesicles. Quantitative analysis showed a significant increase of the relative volume of the Golgi area. The biochemical study demonstrated a significant decrease of corticosterone concentrations in culture medium after monensin addition, and in adrenal glands from treated rats. These results showed that monensin alters the fine structure of adrenal cortex Golgi complex and inhibits corticosteroidogenesis, which supports the probable role of the Golgi complex in the regulation of steroidogenesis.     

Immunotherapy as a treatment of American cutaneous leishmaniasis: preliminary studies in Brazil.

A prophylactic vaccine composed of killed promastigotes of five stocks of Leishmania was tested as an immunotherapeutic agent against American cutaneous leishmaniasis (ACL). The agent was administered by deep intramuscular injection daily for 10 days, followed by a 10-day interval. Out of 62 patients so treated, 47 (76%) were considered clinically cured; 41 required 2-10 treatment courses and the other six 11-19 courses. None of the patients treated by immunotherapy displayed adverse side-effects. Immunotherapy proved to be effective in the treatment of single cutaneous lesions, multiple cutaneous lesions and in cases of mucocutaneous leishmaniasis. In comparison with chemotherapy (Glucantime), immunotherapy is less efficient and more prolonged but can be safely used when antimonials are contra-indicated or are found to be ineffective. Consideration is given to the treatment of victims of ACL living in rural areas remote from a medical centre.     

Phenotypic divergence and inter-specific trait correlation in a plant-pollinator/seed predator mutualism

Plant-pollinator interactions have been suggested as key drivers of morphological divergence and speciation of the involved taxa. These interactions can also promote sexual dimorphism in both the plant and pollinator, particularly if the pollinator is also a seed-eater and/or exerts different selection pressures on male and female plants. Here we tested the hypotheses that plant-pollinator interactions can be reflected in trait variation and sexual dimorphism in both organisms within and across populations. Across nine European populations, we examined intraspecific variation and sexual dimorphism in phenotypic traits potentially involved in the plant–insect interaction of the dioecious white campion Silene latifolia (Caryophyllaceae) and its specialist pollinator Hadena bicruris (Noctuidae). This interaction is expected to entail sex-specific selective pressures, as female moths lay eggs on female plants and the larvae predate on the seeds during their development. We compared divergence in phenotypic traits among populations and between sexes within populations, examined correlations between plant and pollinator traits, and between phenotypic distances and genetic distances among co-occurring populations for both plants and insects. We found key differences in phenotypic traits across populations of both the plant and moth, though only in the moth were these differences correlated with geographic distances. We also found evidence for sexual dimorphism in the plant but not in the pollinator. Evolution of floral sexual dimorphism in S. latifolia most likely results from the joint contribution of different selective forces, including biotic interactions with H. bicruris moths.