Complete Turnover Research Articles

Biosynthesis of brevinic acid from lawsone.

The menaquinone-pathway (men) is widespread in bacteria and key to the biosynthesis of intriguing small molecules such as the essential vitamin menaquinone and the natural dye lawsone. The violet molecule brevinic acid is another proposed product of men, but its direct biosynthetic precursor has remained doubtful. In this study, we isolated brevinic acid from E. coli and confirmed its non-enzymatic formation from lawsone and homocysteine involving an intermediate acetylation or phosphorylation step. We furthermore compared our proposed substrates in a non-enzymatic assay against the previously hypothesized precursor DHNA and showed that the reaction with activated lawsone derivatives proceeded faster, more selective, and with complete turnover. This supports our proposed biosynthesis of brevinic acid from lawsone and enables a cost effective, larger-scale synthesis of brevinic acid.

Variability of winter cooling affects intensity of phytoplankton spring blooms – how resilient is the ciliate assemblage composition to changes in food availability?

After years of partial winter mixing in Lake Zurich (Switzerland), a complete turnover of the water column reoccurred during winter/spring 2021. It was favored by a cold, windy winter and a small difference of water temperatures between the surface zone and a hypolimnion (deep water zone) that had gradually warmed during the previous years. The trend of declining phytoplankton spring blooms due to incomplete winter mixing was interrupted by mass development of algae due to the upwelling of nutrients accumulated in the hypolimnion. The effects of this singular deep mixing on the microbial food web during spring were studied in a high-frequency sampling campaign and compared with data from two years of partial winter mixing (2020 and 2022). A particular focus was put on the quantitative composition of the ciliate assemblage. Our results showed that not all organisms reacted equally to the nutrient (phosphorus) boost in the surface zone. Centric diatoms and cryptophytes profited most directly from the deep mixing, outcompeting the otherwise dominant cyanobacterium Planktothrix rubescens. Heterotrophic bacteria and their top predators, the ‘heterotrophic nanoflagellates’ trophic guild, were less affected by the nutrient supply and showed only short-lived increases of maximal biomass. The assemblage composition of ciliate morphotypes was highly resilient over the three years, presumably due to the range of acceptable food items of the predominant omnivorous species. However, numerous ciliate morphotypes showed brief mass development in 2021, and Balanion planctonicum, small Urotricha species and tintinnids were significantly more frequent than in 2020/2022. Small interception-feeding morphotypes apparently profited from the rich supply of their cryptomonad food, and tintinnid morphotypes additionally benefited from the availability of building material (e.g., centric diatom shells) for their loricae. In summary, we show that effects of lake warming in deep stratifying lakes are not as unidirectional as previously presumed, and we reveal resilience of the pelagic ciliate morphotype assemblage to lake warming related interannual variability in Lake Zurich.

Late Jurassic–Early Cretaceous dinosaur track assemblages from northwestern Hebei Province, China: Implications for paleoenvironment and paleoecology

The relationship between the Middle–Late Jurassic Yanliao Biota and the Early Cretaceous Jehol Biota has long been unresolved due to an approximately 20 Ma “vertebrate fossil gap”. However, a large number of dinosaur tracks have been reported from the Tuchengzi/Houcheng Formation in northern Hebei–western Liaoning, which occupies the stratigraphic position between the Yanliao Biota and the Jehol Biota. This paper presents new discoveries of diverse dinosaur track assemblages from the Upper Jurassic–Lower Cretaceous Houcheng Formation in the Shangyi Basin, northwestern Hebei Province, China. Based on the ichnological analyses, tracks are assigned to the sauropod Parabrontopodus, theropod Grallator, Anchisauripus, Eubrontes, and Therangospodus. The theropod tracks were likely produced by small-sized feathered theropod dinosaurs (Coelurosauria) that thrived in both the Yanliao Biota and the Jehol Biota. These findings imply that these two biotas evolved successively, without evidence of a complete turnover or extinction of biotas. Sedimentological studies of the tracksites reveal their occurrence in diverse sedimentary environments, including braided sandbar, floodplain, and deltaic plain. The coexistence of highly diverse dinosaur tracks with various preservation environments indicates that the living environment during that time was relatively comfortable. The increased diversity of dinosaur tracks in the upper part of the Houcheng Formation closely aligns with the intense volcanic activity of the Zhangjiakou Formation in northwestern Hebei Province. This suggests that volcanic activity likely served a crucial function in the proliferation of the dinosaur fauna in the Shangyi Basin and northern North China during the earliest Cretaceous.

Substrate Turnover Dynamics Guide Ketol-Acid Reductoisomerase Redesign for Increased Specific Activity.

The task of adapting enzymes for specific applications is often hampered by our incomplete ability to tune and tailor catalytic functions, particularly when seeking increased activity. Here, we develop and demonstrate a rational approach to address this challenge, applied to ketol-acid reductoisomerase (KARI), which has uses in industrial-scale isobutanol production. While traditional structure-based computational enzyme redesign strategies typically focus on the enzyme-bound ground state (GS) and transition state (TS), we postulated that additionally treating the underlying dynamics of complete turnover events that connect and pass through both states could further elucidate the structural properties affecting catalysis and help identify mutations that lead to increased catalytic activity. To examine the dynamics of substrate conversion with atomistic detail, we adapted and applied computational methods based on path sampling techniques to gather thousands of QM/MM simulations of attempted substrate turnover events by KARI: both productive (reactive) and unproductive (nonreactive) attempts. From these data, machine learning models were constructed and used to identify specific conformational features (interatomic distances, angles, and torsions) associated with successful, productive catalysis. Multistate protein redesign techniques were then used to select mutations that stabilized reactive-like structures over nonreactive-like ones while also meeting additional criteria consistent with enhanced specific activity. This procedure resulted in eight high-confidence enzyme mutants with a significant improvement in calculated specific activity relative to wild type (WT), with the fastest variant's increase in calculated k cat being (2 ± 1) × 104-fold. Collectively, these results suggest that introducing mutations designed to increase the population of reaction-promoting conformations of the enzyme-substrate complex before it reaches the barrier can provide an effective approach to engineering improved enzyme catalysts.

Engineering complete delocalization of single particle states in a class of one dimensional aperiodic lattices: A quantum dynamical study

We study quantum dynamics of a wave packet on a class of one dimensional decorated aperiodic lattices, described within a tight binding formalism. We look for the possibility of finding extended single particle states even in the absence of any translational periodicity. The chosen lattices are stubbed with one or more atoms, tunnel coupled to the backbone, thereby introducing a minimal quasi-one dimensionality. It is seen that, for a group of such lattices a certain correlation between the numerical values of the hopping amplitudes leads to a complete delocalization of single particle states. In some other cases, a special value of a magnetic flux trapped in the loops present in the geometries delocalize the states, leading to a flux driven insulator to metal transition. The mean square displacement, temporal autocorrelation function, the time dependence of the inverse participation ratio, or the information entropy – the so-called hallmarks of studying localization based on dynamics – all of them indicate such a complete turnover in the nature of the single particle states and the character of the energy spectrum under suitable conditions. The results shown in this work using quasiperiodic lattices of the Fibonacci family are much more general and hold good even for a randomly disordered arrangement of the building blocks of the systems considered, and indicate a subtle universality class under which these lattices can be grouped.

Biotic and abiotic factors driving water hyacinth, Pontederia crassipes, phenology in Nyanza Gulf, Lake Victoria, Kenya

While isolated patches of water hyacinth have persisted in most parts of Lake Victoria since the rapid decline in biomass beginning in 1999/2000, Nyanza Gulf has maintained extensive but cyclical coverage over the years. High water hyacinth productivities were found to coincide with the western region associated with upwelling and regenerated nutrients, and also with periods of complete lake turnover. River discharge sites, which are numerous in the eastern region, expressed relatively low water hyacinth productivities. High productivity meant better nutritional quality, a state preferred by the Neochetina weevils. Although the difference in productivities between the eastern and western regions were statistically insignificant, the feeding scars were notably different. This implies that any slight change in water hyacinth’s nutritional quality as a result of change in resource water quality, significantly affects the weevil’s productivities. During complete lake turnover, water hyacinth productivity is highly enhanced, likely due to upwelling of hypolimnetic nutrient enriched waters with subsequent spontaneous weevil invasion. During times of such high nutrient quality, the rates of leaf turnover outstrips the herbivory by the weevils. The nutrient dynamics from primary sources coupled with secondary regenerated loads through lake turnovers influences the water hyacinth’s varying nutritional quality and weevil population, which ultimately determines the water hyacinth phenology within the semi-enclosed Nyanza Gulf. The objectives of this study were to study the spatial influence of resource water quality to the consumer water hyacinth productivity and how temporal hydrologic dynamics drives its cyclicity.

The variation and evolution of complete human centromeres

Human centromeres have been traditionally very difficult to sequence and assemble owing to their repetitive nature and large size1. As a result, patterns of human centromeric variation and models for their evolution and function remain incomplete, despite centromeres being among the most rapidly mutating regions2,3. Here, using long-read sequencing, we completely sequenced and assembled all centromeres from a second human genome and compared it to the finished reference genome4,5. We find that the two sets of centromeres show at least a 4.1-fold increase in single-nucleotide variation when compared with their unique flanks and vary up to 3-fold in size. Moreover, we find that 45.8% of centromeric sequence cannot be reliably aligned using standard methods owing to the emergence of new α-satellite higher-order repeats (HORs). DNA methylation and CENP-A chromatin immunoprecipitation experiments show that 26% of the centromeres differ in their kinetochore position by >500 kb. To understand evolutionary change, we selected six chromosomes and sequenced and assembled 31 orthologous centromeres from the common chimpanzee, orangutan and macaque genomes. Comparative analyses reveal a nearly complete turnover of α-satellite HORs, with characteristic idiosyncratic changes in α-satellite HORs for each species. Phylogenetic reconstruction of human haplotypes supports limited to no recombination between the short (p) and long (q) arms across centromeres and reveals that novel α-satellite HORs share a monophyletic origin, providing a strategy to estimate the rate of saltatory amplification and mutation of human centromeric DNA.

Age and growth analysis of Loliginidae squid paralarvae in the NW Spanish coast using statolith increment counts

Knowledge of recruitment to a fishery is particularly important in short-lived species, like most cephalopods, in which there is a complete turnover of individual every 1 or 2 years. In this study, age, body length, statolith length and growth rates of loliginid paralarvae (Alloteuthis media, A. subulata and Loligo vulgaris) were determined to evaluate the form of the growth curve and differences between species and hatching seasons. A total of 222 paralarvae collected in zooplankton samples along the Galician coast (NW Spain) were used to determine relationships between dorsal mantle length (DML), statolith length (SL) and the number of increments (NI)) deposited in the statolith. The paralarvae of L. vulgaris were between 1 and 35 days old, while both Alloteuthis species ranged in age from 1 to 54 days. Generalised additive models (GAMs) revealed non-linear growth in DML, with L. vulgaris exhibiting higher DML-at-age than Alloteuthis species. The best parametric model fit for these data was obtained using exponential regressions. The SL–NI relationship also differed between species, with L. vulgaris having larger statolith length at age. The paralarvae of L. vulgaris and A. media had two well-differentiated hatching peaks, one in late spring-early summer (beginning of the upwelling season) and another peak in late autumn (end of the upwelling season). Alloteuthis subulata had an earlier hatching peak in spring than in the other two loliginid species—and the second peak in autumn was barely visible, possibly because this species occurs further north in areas not sampled in autumn.

The Impact of Procuring Per Offer, Turnover of Absolute Resource, Return on Value and Debt Asset Ratio on Offer Value of Maufactur Area Recorded on the Indonesia Stock Trade Period 2019 - 2022

The value of the money is going to decrease because of inflation, so we have to invest in an investment asset. The investment tool explored in this research is c-stock which uses financial ratios to determine whether financial ratios are correlated with stock prices in order to identify capital intensive companies. This research uses ratios such as EPS TATO ROE and asset or debt ratio to provide profitability. This study has been carried out in the case of manufacturing companies listed on IDX, using Eviews version 10 as a data processing tool. The primary sampling method was applied in this study, as it is the standard of sampling. From 2019 to 2022 the samples were six companies with research data and therefore 32 observation reports have been collected. Because of the review, it is known that (1) Profit per share emphatically affects stock costs. The meaning of 00154 demonstrates this so H1 is acknowledged. ( 2) The complete resource turnover rate essentially affects the stock cost as confirmed by the meaning of 01040 so H2 is dismissed. ( 3) Return on value emphatically affects stock cost ( ) which is demonstrated at the importance level 00390 so H3 is acknowledged. ( 4) The obligation to resource rate affects share costs, this is validated by a critical worth of0.0719 so H4 is dismissed;( 5) accomplished contemporaneous Experimental outcomes calculation results F of3.103040 with probability0.031819 can be closed in the event that all factors have a huge impact contemporaneously on costs of stock. The aftereffects of the retrogression examination show the adjusted worth( r2) of0.213441, implies that varieties in Profit per Offer, Advancement of All out Resource, Return on Value, and Obligation to implies rate can make sense of the21.34 of changes in stock value, the remaining78.66 is made sense of not analyzed by different factors in this review.

Engineered lentivirus-derived nanoparticles (LVNPs) for delivery of CRISPR/Cas ribonucleoprotein complexes supporting base editing, prime editing and in vivo gene modification.

Implementation of therapeutic in vivo gene editing using CRISPR/Cas relies on potent delivery of gene editing tools. Administration of ribonucleoprotein (RNP) complexes consisting of Cas protein and single guide RNA (sgRNA) offers short-lived editing activity and safety advantages over conventional viral and non-viral gene and RNA delivery approaches. By engineering lentivirus-derived nanoparticles (LVNPs) to facilitate RNP delivery, we demonstrate effective administration of SpCas9 as well as SpCas9-derived base and prime editors (BE/PE) leading to gene editing in recipient cells. Unique Gag/GagPol protein fusion strategies facilitate RNP packaging in LVNPs, and refinement of LVNP stoichiometry supports optimized LVNP yield and incorporation of therapeutic payload. We demonstrate near instantaneous target DNA cleavage and complete RNP turnover within 4 days. As a result, LVNPs provide high on-target DNA cleavage and lower levels of off-target cleavage activity compared to standard RNP nucleofection in cultured cells. LVNPs accommodate BE/sgRNA and PE/epegRNA RNPs leading to base editing with reduced bystander editing and prime editing without detectable indel formation. Notably, in the mouse eye, we provide the first proof-of-concept for LVNP-directed in vivo gene disruption. Our findings establish LVNPs as promising vehicles for delivery of RNPs facilitating donor-free base and prime editing without formation of double-stranded DNA breaks.

A test of the Geographic Mosaic Theory of Coevolution: investigating widespread species of Amazonian Protium (Burseraceae) trees, their chemical defenses, and their associated herbivore faunas

IntroductionPlants and their insect herbivores represent a large fraction of the species in Amazonian forests and are often directly implicated in the origin and maintenance of biodiversity at local and regional scales. How these interactions may change over geographic distance is unknown because very few studies have investigated the herbivore fauna and defense chemicals of any host plant species at multiple sites in tropical forests. One hypothesis, the Geographic Mosaic Theory of Coevolution, predicts that if herbivore assemblages turn over in different parts of a plant’s range, then plant defense chemicals should also change, reflecting local selection pressures.MethodsWe tested this theory by studying 12 species of Protium (Burseraceae) trees that occur in both Iquitos, Peru, and Manaus, Brazil, in rainforests separated by 1500 km. We surveyed all insects observed directly feeding on the plants in both locations for 48 weeks in Manaus and 64 weeks in Iquitos. We analyzed the secondary metabolites in the leaves of all species in both locations using GC/MS and HPLC.Results and DiscussionAlthough in both locations we found that Protium herbivores were dominated by insects from the orders Hemiptera, Coleoptera and Lepidoptera, we found almost complete turnover in the herbivore species composition in the two sites, and each host plant species had a different assemblage of herbivores in each location. Comparing the phylogenetic beta-diversity, we found low similarity in herbivore phylogenetic relatedness between host plant species in the two locations. However, the secondary metabolites found within a Protium species were similar across the two locations. We found no strong evidence that individuals from a host plant species in Iquitos or Manaus expressed locally-adapted defense chemicals, as individuals from geographic locations did not form clusters when looking at patterns of chemical similarity. These results are not consistent with the Geographic Mosaic Theory of Coevolution. The most intriguing pattern we found was a strong correlation between the diversity of herbivores per host plant species in both locations. We also found that plants with high chemical richness had lower numbers of herbivore species and numbers of total herbivores in both locations. We conclude that high chemical diversity is the most effective strategy for Protium trees to reduce insect herbivore attacks. We speculate that each secondary metabolite is effective at repelling only a few insect herbivores, and that different chemicals are likely effective in different parts of a plants’ geographic range. Future studies should investigate additional locations and additional natural enemies (i.e., fungal pathogens) to test the hypothesis that chemical diversity reduces attack from natural enemies and may explain the ecological and evolutionary success of rainforest trees over time and space.

Exceptions to the temperature–size rule: no Lilliput Effect in end‐Permian ostracods (Crustacea) from Aras Valley (northwest Iran)

AbstractThe body size of marine ectotherms is often negatively correlated with ambient water temperature, as seen in many clades during the hyperthermal crisis of the end‐Permian mass extinction (c. 252 Ma). However, in the case of ostracods, size changes during ancient hyperthermal events are rarely quantified. In this study, we evaluate the body size changes of ostracods in the Aras Valley section (northwest Iran) in response to the drastic warming during the end‐Permian mass extinction at three taxonomic levels: class, order, species. At the assemblage level, the warming triggers a complete species turnover in the Aras Valley section, with larger, newly emerging species dominating the immediate post‐extinction assemblage for a short time. Individual ostracod species and instars do not show dwarfing or a change in body size as an adaptation to the temperature stress during the end‐Permian crisis. This may indicate that the ostracods in the Aras Valley section might have been exceptions to the temperature–size rule (TSR), using an adaptation mechanism that does not involve a decrease in body size. This adaptation might be similar to the accelerated development despite constant instar body sizes that can be observed in some recent experimental studies of ostracod responses to thermal stress.

Functional importance of groups I and II chitinases in cuticle chitin turnover during molting in a wood-boring beetle, Monochamus alternatus

Insects must periodically replace their old cuticle/exoskeleton with a new one in a process called molting or ecdysis to allow for continuous growth through sequential developmental stages. Many RNA interference (RNAi) studies have demonstrated that certain chitinases (CHTs) play roles in this vital physiological event because knockdown of these CHT genes resulted in developmental arrest during the ensuing molting period in several insect species. In this research we analyzed the functions of group I (MaCHT5) and group II (MaCHT10) CHT genes in molting of the Japanese pine sawyer, Monochamus alternatus, an important forest pest known as a major vector of the pinewood nematode. Real-time qPCR revealed that these two CHT genes differ in their expression patterns during late stages of development. Depletion of either MaCHT5 or MaCHT10 transcripts by RNAi resulted in lethal larval-pupal and pupal-adult molting defects depending on the double-stranded RNA (dsRNA) injection timing during development. The insects were unable to shed their old cuticle and died. Furthermore, transmission electron microscopic analysis revealed that, unlike dsEGFP-treated controls, dsMaCHT5- and dsMaCHT10-treated pharate adults exhibited a failure of degradation of the endocuticular layer of their old pupal cuticle, retaining nearly intact horizontal chitinous laminae and vertical pore canal fibers. Both enzymes were indispensable for complete turnover of the chitinous old endocuticle, which is critical for insect molting. The possible functions of two spliced variants of MaCHT10, namely, MaCHT10a and MaCHT10b, are also discussed. Our results add to the knowledge base for further functional studies of insect chitin catabolism by revealing the relative importance of both MaCHT5 and MaCHT10 in chitin turnover with subtle differences in their action. These essential genes and their encoded proteins are potential targets to manipulate for controlling populations of M. alternatus and other pest insects.

Bioprocessing of Waste for Renewable Chemicals and Fuels to Promote Bioeconomy

The world’s rising energy needs, and the depletion of fossil resources demand a shift from fossil-based feedstocks to organic waste to develop a competitive, resource-efficient, and low-carbon sustainable economy in the long run. It is well known that the production of fuels and chemicals via chemical routes is advantageous because it is a well-established technology with low production costs. However, the use of toxic/environmentally harmful and expensive catalysts generates toxic intermediates, making the process unsustainable. Alternatively, utilization of renewable resources for bioprocessing with a multi-product approach that aligns novel integration improves resource utilization and contributes to the “green economy”. The present review discusses organic waste bioprocessing through the anaerobic fermentation (AF) process to produce biohydrogen (H2), biomethane (CH4), volatile fatty acids (VFAs) and medium chain fatty acids (MCFA). Furthermore, the roles of photosynthetic bacteria and microalgae for biofuel production are discussed. In addition, a roadmap to create a fermentative biorefinery approach in the framework of an AF-integrated bioprocessing format is deliberated, along with limitations and future scope. This novel bioprocessing approach significantly contributes to promoting the circular bioeconomy by launching complete carbon turnover practices in accordance with sustainable development goals.

Substrate Promiscuity and Hyperoxidation Susceptibility as Potential Driving Forces for the Co-evolution of Prx5-Type and Prx6-Type 1-Cys Peroxiredoxin Mechanisms

So-called 1-Cys peroxiredoxins (Prx) employ only one cysteine residue for the reduction of hydroperoxides and require an external thiol for the reduction of a reactive sulfenic acid during the catalytic cycle. Hence, 1-Cys Prx, which often belong to the structural Prx5- or the Prx6-type subfamily, are potentially promiscuous enzymes that could react with a variety of thiols. Furthermore, the dependence on an external thiol could affect the susceptibility of 1-Cys Prx to hyperoxidation, i.e., the formation of a sulfinic or sulfonic acid. Here, we compared the reaction mechanisms and kinetics of the Prx5- and Prx6-type enzymes PfAOP and PfPrx6 from the malaria parasite Plasmodium falciparum to address the hyperoxidation susceptibility and potential substrate promiscuity of 1-Cys Prx. While PfAOP did not react with common thiol-disulfide oxidoreductases, the enzyme turned out to be promiscuous regarding the reduction by synthesized glutathione analogues and other low-molecular-weight thiols. Furthermore, we established a complete single turnover experiment for PfAOP with glutathione and the glutaredoxin PfGrx and identified the rapid H2O2-dependent hyperoxidation of PfAOP as the cause for the apparent preference of this Prx5-type enzyme for alkylhydroperoxides in vitro. Unlike promiscuous PfAOP, PfPrx6 was inactive with ascorbate, the physiological low-molecular-weight thiols glutathione, cysteine, cysteamine, coenzyme A, and dihydrolipoamide, as well as physiological protein thiols, including PfTrx1, PfGrx, and the resolving cysteine of the Prx1-type enzyme PfPrx1a in potential hetero-oligomers. Reduction of PfPrx6 was only observed with dithiothreitol and required the presence of a histidine residue, which protects the enzyme from hyperoxidation and is the major structural difference between the active sites of Prx5- and Prx6-type enzymes. We propose two alternative evolutionary adaptations of the 1-Cys Prx mechanism to hyperoxidation and the formation of alternative mixed disulfides that could explain the co-existence of promiscuous Prx5- and protected Prx6-type enzymes in a variety of organisms and subcellular compartments.

Using turnover dynamics to redesign KARI for improved catalytic activity.

Enzymes represent some of the most efficient and precise catalysts known. However, their adoption for specific applications can be hampered by our limited ability to rationally tune and tailor catalytic function, particularly when seeking increased activity, but also when modifying specificity and selectivity. One example of this challenge is in the redesign of ketol-acid reductoisomerase (KARI), whose activity on a native substrate is sometimes the rate-limiting step in proposed industrial isobutanol production pathways. While traditional structure-based computational enzyme redesign strategies would typically focus on the enzyme-bound ground state and transition state, we postulated that additionally treating the underlying dynamics of complete turnover events that connect and pass through both states could further elucidate the structural properties affecting catalysis and help identify mutations that lead to increased catalytic activity.

Placement of plow working bodies for plowing soil slopes

The paper studies the direction turnover layers along slope and placement of working bodies on a plow for plowing slope fields. The diagrams of the turnover of layers on the slope and the layout of the working bodies on the plow are given. It is proved that intermittent grooves ridges, according to agro technical requirements, it is necessary to rotate the layers downhill. It was found that when installing a cut-out spherical disk behind the front cases, a groove is formed above the a is under it. The subsequent layer wrapped in an even body. At the same time, rainwater is sub-arable of soil, which prevents water erosion. The results of one-factor experiments using strain-measuring methods are presented. It has been established that to ensure complete turnover of the layers within their own furrow by the hulls and the formation of the required ridges and intermittent grooves longitudinal distance between and toe even-numbered body ploughshare should be at least 110 cm.

Species composition of shoreline wolf spider communities vary with salinity, but their diets vary with wrack inflow.

Wolf spiders are typically the most common group of arthropod predators on both lake and marine shorelines because of the high prey availability in these habitats. However, shores are also harsh environments due to flooding and, in proximity to marine waters, to toxic salinity levels. Here, we describe the spider community, prey availabilities, and spider diets between shoreline sites with different salinities, albeit with comparatively small differences (5‰ vs. 7‰). Despite the small environmental differences, spider communities between lower and higher saline sites showed an almost complete species turnover. At the same time, differences in prey availability or spider gut contents did not match changes in spider species composition but rather changed with habitat characteristics within a region, where spiders collected at sites with thick wrack beds had a different diet than sites with little wrack. These data suggest that shifts in spider communities are due to habitat characteristics other than prey availabilities, and the most likely candidate restricting species in high salinity would be saline sensitivity. At the same time, species absence from low-saline habitats remains unresolved.

Second Generation Self‐Assembling Dendrimer Combining Supramolecular and Dynamic Covalent Chemistry

AbstractA monodisperse second generation self‐assembled dendrimer has been obtained combining supramolecular chemistry and dynamic covalent chemistry as orthogonal binding moieties. A branching unit 18 and a core 5 were connected via a heteroleptic terpyridine zinc complex exploiting the sterical hindrance of mesitylene units in the 6,6’’‐position of one of the terpyridines as the distinction between the ligands. Solubility problems could be solved by introduction of an ethylhexyl ether. The final sphere of the dendrimer was connected via imines, hydrazones and oximes, whereby the oxime made from O‐methylhydroxylamine (22) led to a complete turnover of all aldehyde functions. Furthermore, no amine signal was left and also no signals for a diffusion constant of the hydroxylamine 22 were observed. The successful formation of the dendrimers was analyzed by 1H NMR and DOSY NMR spectroscopy. Furthermore both, the first and second generation dendrimers could be detected by ESI HRMS.

Complete metamorphosis and microbiota turnover in insects.

The insects constitute the majority of animal diversity. Most insects are holometabolous: during complete metamorphosis their bodies are radically reorganized. This reorganization poses a significant challenge to the gut microbiota, as the gut is replaced during pupation, a process that does not occur in hemimetabolous insects. In holometabolous hosts, it offers the opportunity to decouple the gut microbiota between the larval and adult life stages resulting in high beta diversity whilst limiting alpha diversity. Here, we studied 18 different herbivorous insect species from five orders of holometabolous and three orders of hemimetabolous insects. Comparing larval and adult specimens, we find a much higher beta-diversity and hence microbiota turnover in holometabolous insects compared to hemimetabolous insects. Alpha diversity did not differ between holo- and hemimetabolous insects nor between developmental stages within these groups. Our results support the idea that pupation offers the opportunity to change the gut microbiota and hence might facilitate ecological niche shifts. This possible effect of niche shift facilitation could explain a selective advantage of the evolution of complete metamorphosis, which is a defining trait of the most speciose insect taxon, the holometabola.