Downregulation of p‐COUMAROYL ESTER 3‐HYDROXYLASE in rice leads to altered cell wall structures and improves biomass saccharification

p‐Coumaroyl ester 3‐hydroxylase (C3′H) is a key enzyme involved in the biosynthesis of lignin, a phenylpropanoid polymer that is the major constituent of secondary cell walls in vascular plants. Although the crucial role of C3′H in lignification and its manipulation to upgrade lignocellulose have been investigated in eudicots, limited information is available in monocotyledonous grass species, despite their potential as biomass feedstocks. Here we address the pronounced impacts of C3′H deficiency on the structure and properties of grass cell walls. C3′H‐knockdown lines generated via RNA interference (RNAi)‐mediated gene silencing, with about 0.5% of the residual expression levels, reached maturity and set seeds. In contrast, C3′H‐knockout rice mutants generated via CRISPR/Cas9‐mediated mutagenesis were severely dwarfed and sterile. Cell wall analysis of the mature C3′H‐knockdown RNAi lines revealed that their lignins were largely enriched in p‐hydroxyphenyl (H) units while being substantially reduced in the normally dominant guaiacyl (G) and syringyl (S) units. Interestingly, however, the enrichment of H units was limited to within the non‐acylated lignin units, with grass‐specific γ‐p‐coumaroylated lignin units remaining apparently unchanged. Suppression of C3′H also resulted in relative augmentation in tricin residues in lignin as well as a substantial reduction in wall cross‐linking ferulates. Collectively, our data demonstrate that C3′H expression is an important determinant not only of lignin content and composition but also of the degree of cell wall cross‐linking. We also demonstrated that C3′H‐suppressed rice displays enhanced biomass saccharification.     

Palaeoctopus pelagicus from the Turonian of Mexico reinterpreted as a coelacanth (Sarcopterygian) gular plate

Abstract: The supposed vestige of a cephalopod gladius from Turonian platy limestones at Vallecillo, north‐east Mexico, named Palaeoctopus pelagicus by Fuchs et al. in 2008, is reinterpreted and shown to be a gular plate of a coelacanth fish, possibly of the genus Megacoelacanthus. In addition to the gular plate, two extrascapulars and fin rays of all fins are preserved on one slab and its counterpart. This is the first record of a coelacanth from these lower Turonian strata at Vallecillo, which are rich in fish.     

Subjecting the theory of the small‐island effect to Ockham’s razor

Species–area curves from islands and other isolates often differ in shape from sample‐area curves generated from mainlands or sections of isolates (or islands), especially at finer scales. We examine two explanations for this difference: (1) the small‐island effect (SIE), which assumes the species–area curve is composed of two distinctly different curve patterns; and (2) a sigmoid or depressed isolate species–area curve with no break‐points (in arithmetic space). We argue that the application of Ockham’s razor – the principle that the simplest, most economical explanation for a hypothesis should be accepted over less parsimonious alternatives – leads to the conclusion that the latter explanation is preferable. We hold that there is no reason to assume the ecological factors or patterns that affect the shapes of isolate (or island) curves cause two distinctly different patterns. This assumption is not required for the alternative, namely that these factors cause a single (though depressed) isolate species–area curve with no break‐points. We conclude that the theory of the small‐island effect, despite its present standing as an accepted general pattern in nature, should be abandoned.     

Trans‐3,5,4´‐trimethoxystilbene reduced gefitinib resistance in NSCLCs via suppressing MAPK/Akt/Bcl‐2 pathway by upregulation of miR‐345 and miR‐498

Despite initial dramatic efficacy of epidermal growth factor receptor (EGFR) tyrosine kinase inhibitors (EGFR‐TKIs) in EGFR‐mutant lung cancer patients, subsequent emergence of acquired resistance is almost inevitable. Resveratrol and its derivatives have been found to exert some effects on EGFR‐TKI resistance in non‐small cell lung cancer (NSCLC), but the underlying mechanisms remain unclear. We screened several NSCLC cell lines with gefitinib resistance by MTT assay and analysed the miR‐345/miR‐498 expression levels. NSCLC cells were pre‐treated with a resveratrol derivative, trans‐3,5,4‐trimethoxystilbene (TMS) and subsequently challenged with gefitinib treatment. The changes in apoptosis and miR‐345/miR‐498 expression were analysed by flow cytometry and q‐PCR respectively. The functions of miR‐345/miR‐498 were verified by CCK‐8 assay, cell cycle analysis, dual‐luciferase reporter gene assay and immunoblotting analysis. Our results showed that the expression of miR‐345 and miR‐498 significantly decreased in gefitinib resistant NSCLC cells. TMS pre‐treatment significantly upregulated the expression of miR‐345 and miR‐498 increasing the sensitivity of NSCLC cells to gefitinib and inducing apoptosis. MiR‐345 and miR‐498 were verified to inhibit proliferation by cell cycle arrest and regulate the MAPK/c‐Fos and AKT/Bcl‐2 signalling pathways by directly targeting MAPK1 and PIK3R1 respectively. The combination of TMS and gefitinib promoted apoptosis also by miR‐345 and miR‐498 targeting the MAPK/c‐Fos and AKT/Bcl‐2 signalling pathways. Our study demonstrated that TMS reduced gefitinib resistance in NSCLCs via suppression of the MAPK/Akt/Bcl‐2 pathway by upregulation of miR‐345/498. These findings would lay the theoretical basis for the future study of TMS for the treatment of EGFR‐TKI resistance in NSCLCs.     

Age‐dependent trajectories differ between within‐pair and extra‐pair paternity success

Reproductive success is associated with age in many taxa, increasing in early life followed by reproductive senescence. In socially monogamous but genetically polygamous species, this generates the interesting possibility of differential trajectories of within‐pair and extra‐pair siring success with age in males. We investigate these relationships simultaneously using within‐individual analyses with 13 years of data from an insular house sparrow (Passer domesticus) population. As expected, we found that both within‐ and extra‐pair paternity success increased with age, followed by a senescence‐like decline. However, the age trajectories of within‐ and extra‐pair paternity successes differed significantly, with the extra‐pair paternity success increasing faster, although not significantly, in early life, and showing a delayed decline by 1.5 years on average later in life compared to within‐pair paternity success. These different trajectories indicate that the two alternative mating tactics should have age‐dependent pay‐offs. Males may partition their reproductive effort between within‐ and extra‐pair matings depending on their current age to reap the maximal combined benefit from both strategies. The interplay between these mating strategies and age‐specific mortality may explain the variation in rates of extra‐pair paternity observed within and between species.     

Ubiquitin‐specific protease‐like 1 (USPL1) is a SUMO isopeptidase with essential,non‐catalytic functions

Isopeptidases are essential regulators of protein ubiquitination and sumoylation. However, only two families of SUMO isopeptidases are at present known. Here, we report an activity‐based search with the suicide inhibitor haemagglutinin (HA)‐SUMO‐vinylmethylester that led to the identification of a surprising new SUMO protease, ubiquitin‐specific protease‐like 1 (USPL1). Indeed, USPL1 neither binds nor cleaves ubiquitin, but is a potent SUMO isopeptidase both in vitro and in cells. C13orf22l—an essential but distant zebrafish homologue of USPL1—also acts on SUMO, indicating functional conservation. We have identified invariant USPL1 residues required for SUMO binding and cleavage. USPL1 is a low‐abundance protein that colocalizes with coilin in Cajal bodies. Its depletion does not affect global sumoylation, but causes striking coilin mislocalization and impairs cell proliferation, functions that are not dependent on USPL1 catalytic activity. Thus, USPL1 represents a third type of SUMO protease, with essential functions in Cajal body biology.