Diversity of beetle species and functional traits along gradients of deadwood suggests weak environmental filtering

Background: Gradients in local environmental characteristics may favour the abundance of species with particular traits, while other species decline, or favour species with different traits at the same time, without an increase in average species abundances. Therefore, we asked: do variations in species and traits differ along gradients of deadwood variables? Do species abundance and trait occurrence change with species richness within or between functional groups? Thus, we analysed the beetle assemblages of five forest sites located in Italy, along the Apennines mountains.Methods: From 2012 to 2018 we sampled beetles and five deadwood types in 193 plots to characterise the deadwood gradient: standing dead trees, snags, dead downed trees, coarse woody debris, and stumps. We modelled beetle species relative abundances and trophic traits occurrences against the deadwood variables using joint species distribution models.Results: Out of 462 species, only 77 showed significant responses to at least one deadwood type, with a weak mean response across species. Trophic groups showed mostly negative responses to deadwood variables. Species abundance increased with species richness among sites only for phytophagous and saproxylophagous. Trait occurrence did not increase with species richness among sites, except for phytophagous and saproxylophagous.However, trait occurrence changed significantly with species richness of several trophic groups within some sites.We found that increases in species richness do not result in decreases in species abundance of a given trophic group, but rather null or positive relationships were found suggesting low interspecific competition.Conclusions: Our findings suggest that in Mediterranean mountain forests there is still room for increasing the level of naturalness, at least for what concerns deadwood management. On one side, our findings suggest that competition for deadwood substrates is still low, on the other side they indicate that increasing deadwood volume and types to improve overall beetle richness may increase also beetle abundances.

A novel approach to the dynamic response analysis of Euler-Bernoulli beams resting on a Winkler soil model and subjected to impact loads

This work presents a novel approach to the dynamic response analysis of a Euler-Bernoulli beam resting on a Winkler soil model and subjected to an impact loading.The approach considers that damping has much less importance in controlling the maximum response to impulsive loadings because the maximum response is reached in a very short time,before the damping forces can dissipate a significant portion of the energy input into the system.The development of two sine series solutions,relating to different types of impulsive loadings,one involving a single concentrated force and the other a distributed line load,are presented.This study revealed that when a simply supported Euler-Bernoulli beam,resting on a Winkler soil model,is subject to an impact load,the resulting vertical displacements,bending moments and shear forces produced along the span of the beam are considerably affected.In particular,the quantification of this effect is best observed,relative to the corresponding static solution,via an amplification factor.The computed impact amplification factors,for the sub-grade moduli used in this study,were in magnitude greater than 2,thus confirming the multiple-degree-of-freedom nature of the problem.

Monitoring the abundance of saproxylic red-listed species in a managed beech forest by landsat temporal metrics

Background:Rapid climate changes lead to an increase in forest disturbance,which in turn lead to growing concerns for biodiversity.While saproxylic beetles are relevant indicators for studying different aspects of biodiversity,most are smaller than 2 mm and difficult to sample.This,together with a high number of species and trophic roles,make their study remarkably challenging,time-consuming,and expensive.The Landsat mission provides data since 1984 and represents a powerful tool in this scenario.While we believe that remote sensing data cannot replace on-site sampling and analysis,in this study we aim to prove that the Landsat Time Series(TS)may support the identification of insects’hotspots and consequently guide the selection of areas where to concentrate field analysis.Methods:With this aim,we constructed a Landsat-derived NDVI TS(1984–2020)and we summarised the NDVI trend over time by calculating eight Temporal Metrics(TMs)among which four resulted particularly successful in predicting the amount of saproxylic insects:(i)the slope of the regression line obtained by linear interpolating the NDVI values over time;(ii)the Root Mean Square Error(RMSE)between the regression line and the NDVI TS;(iii)the median,and the(iv)minimum values of the NDVI TS.The study area consists of four monitoring sectors in a Mediterranean-managed beech forest located in the Apennines(Molise,Italy),where 60 window flight traps for flying beetles were installed.First,the saproxylic beetle's biodiversities of monitoring sectors were quantified in terms of species richness and alpha-diversity.Second,the capability of TMs in predicting the richness of saproxylic beetles family and trophic categories was assessed in terms of Pearson's product-moment correlation.Results:The alpha diversity and species richness analysis indicate dissimilarities across the four monitored sectors(Shannon and Simpson's index ranging between 0.67 to 2.31 and 0.69 to 0.88,respectively),with Landsat TS resulting in effective predictors for estimating saproxylic beetle richness.The strongest correlation was reached between the Monotomidae family and the RMSE temporal metric(R=0.66).The mean absolute correlation(r)between the NDVI TMs and the saproxylic community was 0.46 for Monotomidae,0.31 for Cerambycidae,and 0.25 for Curculionidae.Conclusions:Our results suggest that Landsat TS has important implications for studying saproxylic beetle distribution and,by helping the selection of monitoring areas,increasing the amount of information acquired while decreasing the effort required for field analysis.

TCP14 and TCP15 Mediate the Promotion of Seed Germination by Gibberellins in Arabidopsis thaliana

Dear Editor,Seed germination is a major developmental transition in a plant＇s life that involves the concerted action of several genetic and physiological pathways （Holdsworth et al., 2008）, and mostly consists of the resumption of embryo growth after a long quiescence imposed during seed maturation. In mature seeds, germination is repressed by abscisic acid （ABA）, while favorable environmental conditions promote gibberellin （GA） biosynthesis and decrease ABA （Holdsworth et al., 2008）. The increase in GA levels is essential for the rupture of testa and endosperm （Lee et al., 2002）. The activation of cell division in the embryo is an integral part of germination that precedes the protrusion of the root through the seed coat. In Arabidopsis, this activation has been linked to significant early changes in the expression of cell-cycle elements （Masubelele et al., 2005）. In the root apical meristem （RAM）, GAs regulate cell divisions （Achard et al., 2009; 0beda-Tomás et al., 2009）. Similarly, the transcription factors （TFs） TEOSINTE BRANCHED1/ CYCLOIDEA/PROLIFERATING CELL FACTOR14 （TCP14） and TCP15 have been proposed to regulate cell proliferation （Kieffer et al., 2011）. Moreover, the activity of TCP14 is necessary to undergo seed germination and, remarkably, seeds lacking this activity are hypersensitive to the negative effects on germination of GA biosynthesis inhibitor paclobutrazol, suggesting a functional relationship between this TF and GAs （Tatematsu et al., 2008）. Taking these observations into account, we hypothesized that TCP14 and TCP15 mediate GA-dependent activation of the cell cycle during germination.

Candidate genes have sex-specific effects ontiming of spring migration and moult speedin a long-distance migratory bird

The timing of major life-history events, such as migration and moult, is set by endogenous circa-dian and circannual clocks, that have been well characterized at the molecular level. Conversely,the genetic sources of variation in phenology and in other behavioral traits have been sparsely ad-dressed. It has been proposed that inter-individual variability in the timing of seasonal events mayarise from allelic polymorphism at phenological candidate genes involved in the signaling cascadeof the endogenous clocks. In this study of a long-distance migratory passerine bird, the willowwarbler Phylloscopus trochilus, we investigated whether allelic variation at 5 polymorphic loci of 4candidate genes （Adcyapl, Clock, Crebl, and Npas2）, predicted 2 major components of the annualschedule, namely timing of spring migration across the central Mediterranean sea and moultspeed, the latter gauged from ptilochronological analyses of tail feathers moulted in the Africanwinter quarters. We identified a novel Clockgene locus （Clock region 3） showing polyQ polymorph-ism, which was however not significantly associated with any phenotypic trait. Npas2 allele sizepredicted male （but not female） spring migration date, with males bearing longer alleles migratingsignificantly earlier than those bearing shorter alleles. Crebl allele size significantly predicted male（but not female） moult speed, longer alleles being associated with faster moult. All othergenotype-phenotype associations were statistically non-significant. These findings provide newevidence for a role of candidate genes in modulating the phenology of different circannual activ-ities in long-distance migratory birds, and for the occurrence of sex-specific candidate gene effects.

AtSYP51/52 Functions Diverge in the Post-Golgi Traffic and Differently Affect Vacuolar Sorting

Plant sensitive factor attachment protein receptors （SNAREs） encoded by genes of the same sub-family are generally considered as redundant in promoting vesicle-associated membrane fusion events. Nonetheless, the application of innovative experimental approaches highlighted that members of the same gene sub-family often have different functional specificities. In this work, two closely related Qc-SNAREs--the AtSYP51 and the AtSYP52--are compared in their ability to influence different secretory pathways. Their role in the vesicle sorting to the central vacuole has been revised and they were found to have a novel inhibitory function. When transiently overexpressed, the SYP51 and the SYP52 distributed between the TGN and the tonoplast. Our data demonstrate that these SYPs （syntaxin of plants） act as t-SNARE when present on the membrane of TGN/PVC, whereas they behave as inhibitory or interfering SNAREs （i-SNAREs） when they accumulate on the tonoplast. Moreover, the performed functional analysis indicated that the AtSYP51 and the AtSYP52 roles differ in the traffic to the vacuole. The findings are a novel contribution to the functional characterization of plant SNAREs that reveals additional non-fusogenic roles.

PGR5-PGRL1-Dependent Cyclic Electron Transport Modulates Linear Electron Transport Rate in Arabidopsis thaliana

Plants need tight regulation of photosynthetic electron transport for survival and growth under environ- mental and metabolic conditions. For this purpose, the linear electron transport （LET） pathway is supple- mented by a number of alternative electron transfer pathways and valves. In Arabidopsis, cyclic electron transport （CET） around photosystem I （PSI）, which recycles electrons from ferrodoxin to plastoquinone, is the most investigated alternative route. However, the interdependence of LET and CET and the relative importance of CET remain unclear, largely due to the difficulties in precise assessment of the contribution of CET in the presence of LET, which dominates electron flow under physiological conditions. We there- fore generated Arabidopsis mutants with a minimal water-splitting activity, and thus a low rate of LET, by combining knockout mutations in Psb01, PsbP2, PsbQ1, PsbQ2, and PsbR loci. The resulting 45 mutant is viable, although mature leaves contain only ~20% of wild-type naturally less abundant Psb02 protein. 45 plants compensate for the reduction in LET by increasing the rate of CET, and inducing a strong non-photochemical quenching （NPQ） response during dark-to-light transitions. To identify the molecular origin of such a high-capacity CET, we constructed three sextuple mutants lacking the qE component of NPQ （45 npq4-1）, NDH-mediated CET （45 crr4-3）, or PGR5-PGRLl-mediated CET （45 pgrS）. Their analysis revealed that PGR5-PGRLl-mediated CET plays a major role in ~pH formation and induction of NPQ in C3 plants. Moreover, while pgr5 dies at the seedling stage under fluctuating light conditions, 45 pgr5 plants are able to survive, which underlines the importance of PGR5 in modulating the intersystem electron transfer.

“Love Is Strong, and You＇re so Sweet”： JAGGER Is Essential for Persistent Synergid Degeneration and Polytubey Block in Arabidopsis thaliana

Successful double fertilization and subsequent seed development in flowering plants requires the delivery of two sperm cells, transported by a pollen tube, into the embryo sac of an ovule. The embryo sac cells tightly control synergid cell death, and as a result the polyspermy block. Arabinogalactan proteins are highly glycosylated proteins thought to be involved in several steps of the reproductive process. We show that JAGGER, Arabinogalactan Protein 4, is an important molecule necessary to prevent the growth of multiple pollen tubes into one embryo sac in Arabidopsis thaliana. In jagger, an AGP4 knockout mutant, the pistils show impaired pollen tube blockage as a consequence of the survival of the persistent synergid. JAGGER seems to be involved in the signaling pathway that leads to a blockage of pollen tube attraction. Our results shed light on the mechanism responsible for preventing polyspermy in Arabidopsis and for safe- guarding successful fertilization of all ovules in one pistil, ensuring seed set and the next generation.

Integrin-targeting with peptide-bioconjugated semiconductor-magnetic nanocrystalline heterostructures

Binary asymmetric nanocrystals （BNCs）, composed of a photoactive TiO2 nanorod joined with a superparamagnetic γ-Fe203 spherical domain, were embedded in polyethylene glycol modified phospholipid micelle and successfully bioconjugated to a suitably designed peptide containing an RGD motif. BNCs represent a relevant multifunctional nanomaterial, owing to the coexistence of two distinct domains in one particle, characterized by high photoactivity and magnetic properties, that is particularly suited for use as a phototherapy and hyperthermia agent as well as a magnetic probe in biological imaging. We selected the RGD motif in order to target integrin expressed on activated endothelial cells and several types of cancer cells. The prepared RGD-peptide/BNC conjugates, comprehensively monitored by using complementary optical and structural techniques, demon- strated a high stability and uniform dispersibility in biological media. The cytotoxicity of the RGD-peptide/BNC conjugates was studied in vitro. The cellular uptake of RGD-peptide conjugates in the cells, assessed by means of two distinct approaches, namely confocal microscopy analysis and emission spectroscopy determination in cell lysates, displayed selectivity of the RGD-peptide-BNC conjugate for the cw]33 integrin. These RGD-peptide-BNC conjugates have a high potential for theranostic treatment of cancer.