Lagerenyl acetate and lagerenol two tetracyclic triterpenoids with the cycloartane skeleton from Lagerstroemia lancasteri

Lagerenyl acetate and lagerenol two new tetracyclic triterpenoids with the cycloartane skeleton together with four other triterpenoids 2α-hydroxy- 3β-E-p-coumaryloxy-urs-12-en-28-oic acid (jacoumaric acid, isolated as its monoacetylmethylcarboxylate derivative), 2α-hydroxyursolic acid (isolated as its diacetate), germanicyl acetate and friedelin, and sitosterol were isolated from the leaves and twigs of Lagerstroemia lancasteri. The structures of lagerenyl acetate and lagerenol were established as 3β-acetoxycycloart-24-one and 3β-hydroxycycloart-24-one, respectively, on the basis of spectral and chemical evidence.     

Does post-fire abiotic habitat filtering create divergent plant communities in black spruce forests of eastern Canada?

We investigated the role of post-fire residual organic matter (ROM) thickness as a driver of community assembly in eastern Newfoundland. We hypothesized that if post-fire community assembly is predominantly controlled by ROM thickness (an abiotic habitat filter), then post-fire species composition and functional traits should correspond to the depth and distribution of ROM. However, if species interactions (biotic filter) are the primary constraints on community assembly, then post-fire species composition and their functional traits should be independent of the depth and distribution of ROM. We tested these predictions in three relatively mature plant communities, Kalmia angustifolia heath, black spruce (Picea mariana)-Kalmia shrub savannah and black spruce forest. Through pre-fire stand reconstruction, we found evidence that the three communities originated from black spruce forest. ROM thickness in heath was almost twice that of shrub savannah and six times more than forest, suggesting a gradient in fire severity. Distribution of ROM corresponded to patterns in vegetation dominance, where thick ROM (>2 cm) filtered out black spruce in favour of Kalmia. ROM thickness was a strong predictor of vegetation composition and function between heath and forest, but this was not found between the shrub savannah and forest. We attribute this to species interactions and allelopathy, which may have become important when ROM thickness was suitable for both seed (black spruce) and vegetative (Kalmia) regenerating species. Thus, priority effects or “who came first” may have lead to shrub savannah formation when ROM thickness was ~2 cm. We conclude that abiotic habitat filtering of thick ROM (>2 cm) on (primarily) species’ regeneration traits was the primary driver of community divergence from forest to heath and shrub savannah.     

CO-WOA: Novel Optimization Approach for Deep Learning Classification of Fish Image

The most significant groupings of cold-blooded creatures are the fish family. It is crucial to recognize and categorize the most significant species of fish since various species of seafood diseases and decay exhibit different symptoms. Systems based on enhanced deep learning can replace the area's currently cumbersome and sluggish traditional approaches. Although it seems straightforward, classifying fish images is a complex procedure. In addition, the scientific study of population distribution and geographic patterns is important for advancing the field's present advancements. The goal of the proposed work is to identify the best performing strategy using cutting-edge computer vision, the Chaotic Oppositional Based Whale Optimization Algorithm (CO-WOA), and data mining techniques. Performance comparisons with leading models, such as Convolutional Neural Networks (CNN) and VGG-19, are made to confirm the applicability of the suggested method. The suggested feature extraction approach with Proposed Deep Learning Model was used in the research, yielding accuracy rates of 100 %. The performance was also compared to cutting-edge image processing models with an accuracy of 98.48 %, 98.58 %, 99.04 %, 98.44 %, 99.18 % and 99.63 % such as Convolutional Neural Networks, ResNet150V2, DenseNet, Visual Geometry Group-19, Inception V3, Xception. Using an empirical method leveraging artificial neural networks, the Proposed Deep Learning model was shown to be the best model.     

Insight into the location and dynamics of the annexin A2 N-terminal domain during Ca(2+)-induced membrane bridging

Annexin A2 (AnxA2) is a Ca(2+)- and phospholipid-binding protein involved in many cellular regulatory processes. Like other annexins, it is constituted by two domains: a conserved core, containing the Ca(2+) binding sites, and a variable N-terminal segment, containing sites for interactions with other protein partners like S100A10 (p11). A wealth of data exists on the structure and dynamics of the core, but little is known about the N-terminal domain especially in the Ca(2+)-induced membrane-bridging process. To investigate this protein region in the monomeric AnxA2 and in the heterotetramer (AnxA2-p11)(2), the reactive Cys8 residue was specifically labelled with the fluorescent probe acrylodan and the interactions with membranes were studied by steady-state and time-resolved fluorescence. In membrane junctions formed by the (AnxA2-p11)(2) heterotetramer, the flexibility of the N-terminal domain increased as compared to the protein in solution. In "homotypic" membrane junctions formed by monomeric AnxA2, acrylodan moved to a more hydrophobic environment than in the protein in solution and the flexibility of the N-terminal domain also increased. In these junctions, this domain is probably not in close contact with the membrane surface, as suggested by the weak quenching of acrylodan observed with doxyl-PCs, but pairs of N-termini likely interact, as revealed by the excimer-forming probe pyrene-maleimide bound to Cys8. We present a model of monomeric AnxA2 N-terminal domain organization in "homotypic" bridged membranes in the presence of Ca(2+).     

Translation fidelity coevolves with longevity

Whether errors in protein synthesis play a role in aging has been a subject of intense debate. It has been suggested that rare mistakes in protein synthesis in young organisms may result in errors in the protein synthesis machinery, eventually leading to an increasing cascade of errors as organisms age. Studies that followed generally failed to identify a dramatic increase in translation errors with aging. However, whether translation fidelity plays a role in aging remained an open question. To address this issue, we examined the relationship between translation fidelity and maximum lifespan across 17 rodent species with diverse lifespans. To measure translation fidelity, we utilized sensitive luciferase‐based reporter constructs with mutations in an amino acid residue critical to luciferase activity, wherein misincorporation of amino acids at this mutated codon re‐activated the luciferase. The frequency of amino acid misincorporation at the first and second codon positions showed strong negative correlation with maximum lifespan. This correlation remained significant after phylogenetic correction, indicating that translation fidelity coevolves with longevity. These results give new life to the role of protein synthesis errors in aging: Although the error rate may not significantly change with age, the basal rate of translation errors is important in defining lifespan across mammals.     

Conifer Regeneration Problems in Boreal and Temperate Forests with Ericaceous Understory: Role of Disturbance,Seedbed Limitation,and Keytsone Species Change

Conifer regeneration failure in the presence of dense ericaceous cover resulting from the removal of canopy trees by forest harvesting observed in boreal and temperate forest has been attributed to allelopathy, competition, and soil nutrient imbalance. Ecosystem-level alleopathic effect has been argued as a cause for conifer regeneration failure by citing examples from a species-poor boreal forest in northern Sweden with ground vegetation dominated by crowberry (Empetrum hermaphroditum, Ericales) and New Zealand dairy pastures invaded by nodding or musk thistle (Carduus nutans). This article aims to explain the phenomenon of vegetation shift from conifer forest to ericaceous heath by extending the argument of ecosystem-level impact of ericaceous plants and linking the disturbance-mediated regeneration strategies of the dominant conifer species and the understory ericaceous species with the quality of seedbed substrate that influence the direction of secondary succession. It has been argued that fire severity plays a pivotal role in controlling seedbed quality and the regeneration mechanisms of conifers, which in turn determines the direction of post-disturbance succession. The post-fire-dominated ericaceous plants and their habitat-modifying effects have been explained from the point of view of keystone species concept and their role as ecosystem engineers. In the absence of high severity natural fires the canopy keystone species (conifer) fails to regenerate successfully mainly due to limitation of favorable seedbed. On the other hand, the understory ericaceous plants regenerate vigorously by vegetative methods from the belowground components that survived the fire. Forest harvesting by clearcutting or selective cutting also create similar vigorous vegetative regrowth of ericaceous plants, but conifer regeneration suffers from the lack of a suitable seedbed. Thus in the absence of successful conifer regeneration, the vigorously growing understory ericaceous plants become the new keystone species. The new keystone ericaceous species bring about a significant long-term habitat change by rapid accumulation of plyphenol-rich humus. Ericaceous phenolic compounds have been found to inhibit seed germination and seedling growth of conifers. By forming protein-phenol complexes they cause a further reduction of available nitrogen of the already nutrient-stressed habitat. A low pH condition in the presence of phenolic compounds causes the leaching of metallic ions and forms hard iron pans that impair soil water movement. The phenolic allelochemicals of ericaceous humus are also inhibitory to many conifer ectomycorrhizae. On the other hand, ericaceous plants perpetuate in the community by their stress-tolerating strategies as well as their ability to acquire nutrients through ericoid mycorrhizae. Three mechanisms working at the ecosystem level can be suggested as the cause of vegetation shift from forest to ericaceous heath. These are (1) the absence of high severity natural fire and the limitation of suitable conifer seedbed in the presence of thick humus, (2) increased competition resulting from the rapid vegetative regeneration of understory ericaceous plants after forest canopy opening by harvesting or nonsevere fire, and (3) habitat degradation by phenolic allelochemicals of ericaceous plants causing a soil nutrient imbalance and iron pan formation. Thus, a shift in keystone species from conifer to ericaceous plant in the post-disturbance habitat may induce a retrogressive succession due to ecosystem-level engineering effects of the new keystone species. Vegetation management in conifer-ericaceous communities depends on land management objectives. If the objective is to produce timber and other forest products then the control of ericaceous plants and site preparation is necessary after forest harvesting. Ploughing and liming followed by conifer planting and repeated N fertilization has been applied successfully to promote afforestation of Calluna heathlands in Britain. However, such practice has not been proven successful in the reforestation of Kalmia-dominated sites in eastern Canada. If, on the other hand, the land management objective is to maintain heathlands for herbivore production or conservation of cultural landscape, as in the case of certain Calluna-dominated heathland in Western Europe, then moderately hot prescribed burning is useful as a management tool.     

Fine needle aspiration cytologic diagnosis of toxoplasma lymphadenitis. A case report with detection of a Toxoplasma bradycyst in a Papanicolaou-stained smear

BACKGROUND: Fine needle aspiration (FNA) cytologic diagnosis of toxoplasmic lymphadenitis with demonstration of a tissue cyst containing bradyzoites has been very rarely reported. CASE: A 17-year-old female presented with a mobile, painless, 2-cm-diameter swelling over the right suprascapular area. Clinical diagnosis was lipoma. FNA smears showed features of reactive lymphoid hyperplasia, including tingible body macrophages and groups of epithelioid histiocytes. A Toxoplasma cyst with bradyzoites was also demonstrated in a Papanicolaou-stained smear. Following FNA cytodiagnosis, serologic tests revealed a high titer of IgG and the presence of IgM-specific antibodies to Toxoplasma gondii, indicating active/recent disease. CONCLUSION: FNA cytology is a valuable tool for the diagnosis of toxoplasmic lymphadenitis. Papanicolaou stain is appropriate for demonstration of the parasite. Serology is an excellent adjunct in clinching the diagnosis.     

Stabilization of anionic and neutral forms of a fluorophoric ligand at the active site of human carbonic anhydrase I

We synthesized a fluorogenic dansylamide derivative (JB2-48), which fills the entire (15 Å deep) active site pocket of human carbonic anhydrase I, and investigated the contributions of sulfonamide and hydrophobic regions of the ligand structure on the spectral, kinetic, and thermodynamic properties of the enzyme–ligand complex. The steady-state and fluorescence lifetime data revealed that the deprotonation of the sulfonamide moiety of the enzyme bound ligand increases the fluorescence emission intensity as well as the lifetime of the fluorophores. This is manifested via the electrostatic interaction between the active site resident Zn²⁺ cofactor and the negatively charged sulfonamide group of the ligand, and such interaction contributes to about 2.2 kcal/mol (ΔΔG°) and 0.89 kcal/mol (ΔΔG^‡) energy in stabilizing the ground and the putative transition states, respectively. We provide evidence that the anionic and neutral forms of JB2-48 are stabilized by the complementary microscopic/conformational states of the enzyme. The implication of the mechanistic studies presented herein in rationale design of carbonic anhydrase inhibitors is discussed.     

Invaders' control on post-disturbance succession in coastal mangroves

Aims In recent years, coastal mangroves have been frequently affected by large disturbances (cyclones, hurricanes, flooding and tsunamis) and post-disturbance vegetation is often dominated by small stature mangrove, mangrove-associate and non-mangrove species potentially affecting ecosystem functioning. Knowledge on the processes of mangrove vegetation development and recovery (succession) following normal and large disturbances will benefit practitioners in designing robust ecosystem management/restoration plans. Here we propose a conceptual model of disturbance-mediated succession in mangroves.Methods Based on field observations and species' life history traits, we develop conceptual models of mangrove succession under normal disturbance regime and recently experienced increased frequency of large disturbances. We evaluate our conceptual models by conducting a scenario testing experiment.Important findings We suggest two predominant processes affecting mangrove succession after disturbance: propagule limitation due to damage of seed producing mature trees and dispersal barrier resulting from biological invasion associated with large disturbance. We argue that large disturbances affect mature trees more than the small-stature non-tree (shrubs, herbs and climbers) species creating a larger propagule shortage for mangrove tree species than non-tree species. Secondly, large disturbances facilitate invasion of free-floating aquatics, which may interfere with the flow-facilitated propagule dispersal and seedling establishment of mangrove species. In a scenario testing experiment, we have shown that similar levels of disturbance impact vegetation development and recovery differently depending on the presence or absence of invasive species. We conclude that since biological invasion is one of the major drivers of post-disturbance mangrove succession, the dimension of biological invasion should be included in prediction, management and restoration of mangrove forests.     

Controlled surface trap state photoluminescence from CdS QDs impregnated in poly(methyl methacrylate)

A method of microwave (MW) assisted synthesis was employed to prepare cadmium sulfide (CdS) quantum dots (QDs) in dimethylformamide in the presence of poly(methyl methacrylate) (PMMA). The MW irradiation was carried out for a fixed time of 20-30 s and the size of QDs varied from 2.9-5.5 nm. Before each irradiation the solution was cooled down to ambient temperature and the irradiation process was repeated six times. An increase in the intensity and red shift of the characteristic UV-vis absorption peak originating from CdS QDs were observed with repeated MW irradiation, suggesting that the amount of generated CdS QDs increased within the PMMA network and aggregated with repeated MW irradiation. MW irradiation could influence selectively the nucleation and growing rates of PMMA-CdS QDs systems. The broadness and large Stokes shift of the emission from Cd(2+)-rich PMMA-CdS QDs was due to the surface trap state photoluminescence. The recombination of shallow trapped electrons and shallow trapped holes has been considered as the primary source of the surface trap state photoluminescence in Cd(2+)-rich PMMA-CdS QDs. The photoluminescence lifetime was observed to be decreased sharply when the amount of QDs was less, showing the emission decay was dependent on the surface property of PMMA-CdS QDs. The origin of the longer lifetime was due to the involvement of surface trap states and dependent on the amount of CdS QDs present within PMMA and its environment. The effect of the concentration of Cd(2+), S(2-) and PMMA on the generation of CdS QDs within PMMA and the effect of repeated MW irradiation on the optical properties was studied and the results are discussed in this article.