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Royal Society Open Science Nov 2019The origin of the arthropod carapace, an enlargement of cephalic tergites, can be traced back to the Cambrian period. However, its disparity and evolution are still not...
The origin of the arthropod carapace, an enlargement of cephalic tergites, can be traced back to the Cambrian period. However, its disparity and evolution are still not fully understood. Here, we describe a new 'bivalved' arthropod, gen. et sp. nov., based on 102 specimens from the middle Cambrian (Wuliuan Stage) Burgess Shale, Marble Canyon area in British Columbia's Kootenay National Park, Canada. The laterally compressed carapace covers most of the body. It is fused dorsally and merges anteriorly into a conspicuous postero-ventrally recurved rostrum as long as the carapace and positioned between a pair of backwards-facing pedunculate eyes. The body is homonomous, with approximately 40 weakly sclerotized segments bearing biramous legs with elongate endopods, and ends in a pair of small flap-like caudal rami. is interpreted as a suspension feeder possibly swimming inverted, in a potential case of convergence with some branchiopods. A Bayesian phylogenetic analysis places it within a group closely related to the extinct Hymenocarina. is unique in its carapace morphology and overall widens the ecological disparity of Cambrian arthropods and suggests that the evolution of a 'bivalved' carapace and an upside-down lifestyle may have occurred early in stem-group crustaceans.
PubMed: 31827867
DOI: 10.1098/rsos.191350 -
Physiology and Molecular Biology of... Nov 2019The use of pedunculate oak ( L.), along with other tree species, for the afforestation of heavy metal contaminated lands is an attractive prospect. Little, however, is...
The use of pedunculate oak ( L.), along with other tree species, for the afforestation of heavy metal contaminated lands is an attractive prospect. Little, however, is known of tolerance and its antioxidative system response to heavy metal exposure. The main objective of the study was to determine the cadmium-induced changes in antioxidative system of pedunculate oak in an attempt to identify molecular mechanisms underlying Cd tolerance. This may be of great importance in respect of using for phytoremediation purposes. As the response of the antioxidative system to heavy metal contamination can vary within species, the research was conducted on oak seedlings from two different regions of origin. Differences in antioxidative system response of seedlings derived from tested regions of origin were noticed both at the transcript and enzyme activity levels. The obtained results indicate that ascorbate peroxidase (APX; EC 1.11.1.11) and superoxide dismutase (SOD; EC 1.15.1.1) play a first barrier role in oak seedlings response to the oxidative stress caused by Cd exposure. Catalase (CAT; EC 1.11.1.6) is involved in reducing the negative effects of prolonged Cd treatment.
PubMed: 31736541
DOI: 10.1007/s12298-019-00712-1 -
The New Phytologist May 2020Exotic pathogens cause severe damage in natural populations in the absence of coevolutionary dynamics with their hosts. However, some resistance to such pathogens may...
Exotic pathogens cause severe damage in natural populations in the absence of coevolutionary dynamics with their hosts. However, some resistance to such pathogens may occur in naive populations. The objective of this study was to investigate the genetics of this so-called 'exapted' resistance to two pathogens of Asian origin (Erysiphe alphitoides and Phytophthora cinnamomi) in European oak. Host-pathogen compatibility was assessed by recording infection success and pathogen growth in a full-sib family of Quercus robur under controlled and natural conditions. Two high-resolution genetic maps anchored on the reference genome were used to study the genetic architecture of resistance and to identify positional candidate genes. Two genomic regions, each containing six strong and stable quantitative trait loci (QTLs) accounting for 12-19% of the phenotypic variation, were mainly associated with E. alphitoides infection. Candidate genes, especially genes encoding receptor-like-kinases and galactinol synthases, were identified in these regions. The three QTLs associated with P. cinnamomi infection did not colocate with QTLs found for E. alphitoides. These findings provide evidence that exapted resistance to E. alphitoides and P. cinnamomi is present in Q. robur and suggest that the underlying molecular mechanisms involve genes encoding proteins with extracellular signaling functions.
Topics: Ascomycota; Disease Resistance; Phytophthora; Plant Diseases; Quantitative Trait Loci; Quercus
PubMed: 31711257
DOI: 10.1111/nph.16319 -
World Journal of Clinical Cases Jul 2019Because the duodenum is fixed onto the retroperitoneum, duodenal intussusception is usually impossible except in cases of malrotational abnormality. Although cases of...
BACKGROUND
Because the duodenum is fixed onto the retroperitoneum, duodenal intussusception is usually impossible except in cases of malrotational abnormality. Although cases of duodenal intussusception without malrotational abnormalities have been reported, it is unclear whether they constitute true intussusception or simple mucosal prolapse.
CASE SUMMARY
A 66-year-old woman presented with whole-body edema and malaise. Blood analysis indicated severe anemia and cholestasis. Endoscopic examination revealed a pedunculate polyp on the second part of the duodenum that migrated distally with mucosal elongation. Computed tomography showed duodenal intussusception. A tumor as the lead point and retroperitoneal structure, including the head of the pancreas and fat, invaginated beyond the duodenojejunal flexure. She was diagnosed with ampullary adenoma caused repeated intussusception that reduced spontaneously and underwent pancreaticoduodenectomy. Laparotomy showed tumor prolapse beyond the duodenojejunal flexure without intussusception. There was no evidence of malrotational abnormality. She was discharged with no complications.
CONCLUSION
We report true duodenal intussusception without malrotational abnormality. This phenomenon was also associated with mucosal prolapse.
PubMed: 31417932
DOI: 10.12998/wjcc.v7.i14.1857 -
G3 (Bethesda, Md.) Oct 2019The impact of climate change that comes with a dramatic increase of long periods of extreme summer drought associated with heat is a fundamental challenge for European...
The impact of climate change that comes with a dramatic increase of long periods of extreme summer drought associated with heat is a fundamental challenge for European forests. As a result, forests are expected to shift their distribution patterns toward north-east, which may lead to a dramatic loss in value of European forest land. Consequently, unraveling key processes that underlie drought stress tolerance is not only of great scientific but also of utmost economic importance for forests to withstand future heat and drought wave scenarios. To reveal drought stress-related molecular patterns we applied cross-species comparative transcriptomics of three major European oak species: the less tolerant deciduous pedunculate oak (), the deciduous but quite tolerant pubescent oak (), and the very tolerant evergreen holm oak (). We found 415, 79, and 222 differentially expressed genes during drought stress in , , and , respectively, indicating species-specific response mechanisms. Further, by comparative orthologous gene family analysis, 517 orthologous genes could be characterized that may play an important role in drought stress adaptation on the genus level. New regulatory candidate pathways and genes in the context of drought stress response were identified, highlighting the importance of the antioxidant capacity, the mitochondrial respiration machinery, the lignification of the water transport system, and the suppression of drought-induced senescence - providing a valuable knowledge base that could be integrated in breeding programs in the face of climate change.
Topics: Adaptation, Biological; Antioxidants; Computational Biology; Crosses, Genetic; Droughts; Gene Expression Profiling; Gene Expression Regulation, Plant; Gene Ontology; High-Throughput Nucleotide Sequencing; Molecular Sequence Annotation; Quercus; Species Specificity; Stress, Physiological; Transcriptome
PubMed: 31395652
DOI: 10.1534/g3.119.400456 -
Oecologia Sep 2019Sunlight can accelerate the decomposition process through an ensemble of direct and indirect processes known as photodegradation. Although photodegradation is widely...
Sunlight can accelerate the decomposition process through an ensemble of direct and indirect processes known as photodegradation. Although photodegradation is widely studied in arid environments, there have been few studies in temperate regions. This experiment investigated how exposure to solar radiation, and specifically UV-B, UV-A, and blue light, affects leaf litter decomposition under a temperate forest canopy in France. For this purpose, we employed custom-made litterbags built using filters that attenuated different regions of the solar spectrum. Litter mass loss and carbon to nitrogen (C:N) ratio of three species: European ash (Fraxinus excelsior), European beech (Fagus sylvatica) and pedunculate oak (Quercus robur), differing in their leaf traits and decomposition rate, were analysed over a period of 7-10 months. Over the entire period, the effect of treatments attenuating blue light and solar UV radiation on leaf litter decomposition was similar to that of our dark treatment, where litter lost 20-30% less mass and had a lower C:N ratio than under the full-spectrum treatment. Moreover, decomposition was affected more by the filter treatment than mesh size, which controlled access by mesofauna. The effect of filter treatment differed among the three species and appeared to depend on litter quality (and especially C:N), producing the greatest effect in recalcitrant litter (F. sylvatica). Even under the reduced irradiance found in the understorey of a temperate forest, UV radiation and blue light remain important in accelerating surface litter decomposition.
Topics: Forests; France; Plant Leaves; Trees; Ultraviolet Rays
PubMed: 31363838
DOI: 10.1007/s00442-019-04478-x