M. Anand

Abstract Plant traits – the morphological, anatomical, physiological, biochemical and phenological characteristics of plants and their organs – determine how primary producers respond to environmental factors, affect other trophic levels, influence ecosystem processes and services and provide a link from species richness to ecosystem functional diversity. Trait data thus represent the raw material for a wide range of research from evolutionary biology, community and functional ecology to biogeography. Here we present the global database initiative named TRY, which has united a wide range of the plant trait research community worldwide and gained an unprecedented buy‐in of trait data: so far 93 trait databases have been contributed. The data repository currently contains almost three million trait entries for 69 000 out of the world's 300 000 plant species, with a focus on 52 groups of traits characterizing the vegetative and regeneration stages of the plant life cycle, including growth, dispersal, establishment and persistence. A first data analysis shows that most plant traits are approximately log‐normally distributed, with widely differing ranges of variation across traits. Most trait variation is between species (interspecific), but significant intraspecific variation is also documented, up to 40% of the overall variation. Plant functional types (PFTs), as commonly used in vegetation models, capture a substantial fraction of the observed variation – but for several traits most variation occurs within PFTs, up to 75% of the overall variation. In the context of vegetation models these traits would better be represented by state variables rather than fixed parameter values. The improved availability of plant trait data in the unified global database is expected to support a paradigm shift from species to trait‐based ecology, offer new opportunities for synthetic plant trait research and enable a more realistic and empirically grounded representation of terrestrial vegetation in Earth system models.

Synthesis of chitosan mediated silver nanoparticles (Ag NPs) and its characterization were fulfilled by UV–vis spectroscopy, fourier transform infrared spectroscopy, X-ray diffraction and transmission electron microscopy. UV–visible absorption spectrum revealed that the formation efficiency of Ag NPs was increased by the addition of chitosan. In addition, the size decrement of NPs was more remarkable at a higher chitosan concentration. XRD pattern has indicated that Ag NPs were spherical structured and crystalline in nature (JCPDS card no: 65-2871). The AFM and TEM images examined the surface morphology and the size of the synthesized NPs. DLS image confirmed the size distribution and range of the Ag NPs. The synthesized Ag NPs showed highly potent antibacterial and antifungal activities. The study suggested that crustacean waste could be a cheaper source for the production of Ag NPs which could be useful in various medical applications for biomedicine research and may create a new market for sea food with products such as chitin and chitosan. Keywords: Chitosan, Biopolymer, Silver nanoparticles, Antimicrobial activity

OBJECTIVE: To identify the larvicidal activities of silver nano particles synthesised with Rhizophora mucronata (R. mucronata) leaf extract against the larvae of Aedes aegypti (Ae. aegypti) and Culex quinquefasciatus (Cx. quinquefasciatus). METHODS: In vitro larvicidal activities such as LC(50) and LC(90) were assessed for the Ae. aegypti and Cx. quinquefasciatus larval species. Further, characterisation such as UV, XRD, FTIR and AFM analysis were carried out for the synthesised silver nano particles. RESULTS: The LC(50) value of the synthesised silver nano particle was identified as 0.585 and 0.891 mg/L for Ae. aegypti and Cx. quinquefasciatus larvae respectively. Further, the LC(90) values are also identified as 2.615 and 6.291 mg/L for Ae. aegypti and Cx. quinquefasciatus species respectively. The synthesised silver nanoparticles have maximum absorption at 420 nm with the average size of 60-95 nm. The XRD data showed 2θ intense values with various degrees such as 37.10°, 47.66°, 63.97° and 70.01°. The FTIR data showed prominent peaks in (3 426.89, 2 925.49, 2 869.56, 2 346.95, 1 631.49, 1 031.73, 669.18 and 455.12) different ranges. CONCLUSIONS: The biosynthesis of silver nanoparticles with leaf aqueous extract of R. mucronata provides potential source for the larvicidal activity against mosquito borne diseases.

The present study was aimed to identify the antibacterial potential of biosynthesised silver nanoparticles using different plant parts (leaves, bark and root) of Avicenna marina mangrove plant. Of the selected three different parts, the leaf extract showed the maximum synthesis of silver nanoparticles. The in vitro antibacterial assay (100 μg disk−1 concentration) showed the results of maximum zone of inhibition with the E. coli (18.40 ± 0.97 mm), and minimum (10.87 ± 1.33 mm) zone of inhibition with S. aureus but the concentrations of MIC and MBC values ranged between 6.25 and 50.0 μg ml−1 between the selected bacterial strains. The FTIR results of most potent leaf extract-synthesized silver nanoparticles showed the prominent peaks (620.967; 1,061.02; 1,116.58; 1,187.94; 1,280.50; 1,353.79; 1,384.64; 1,598.50; 1,629.56; 2,854.14 and 2,927.42) in different ranges. Further, the results of XRD analysis showed the 2θ intense values (38.11 and 70.57) within the ranges of Bragg’s reflection. In addition, the AFM analysis showed the results of particle sizes (71–110 nm), particle roughness (11.8 nm), maximum height of the particle roughness (111.8 nm), and average maximum height of the particle roughness (57.5 nm). It can be concluded from the present findings that, the biosynthesis of silver nanoparticles from the leaf extract of A. marina can be used as potential antibacterial agents.

Nowadays chitosan nanoparticles (CS NPs) have been extensively considered for biomedical applications. The purpose of this paper is to summarize the results of larvicidal activities of extracted chitosan and synthesized CS NPs from shrimp shells against third-instar larvae of mosquitoe Aedes aegypti (A. aegypti). The CS NPs exhibited higher larvicidal activity in comparison to extracted and commercial chitosan. In the present study, the chitosan was extracted from shrimp shells (Penaues indicus) and the CS NPs were synthesized by a novel method of ionic gelation with sodium tripolyphosphate (TPP) as a reducing agent. The chitosan was morphologically characterized by fourier transforms infrared (FTIR) spectra, X-ray diffraction (XRD) and scanning electron microscope (SEM), whereas the CS NPs were characterized using FTIR, XRD, atomic force microscopy (AFM) and high resolution transmission electron microscopy (HRTEM). The synthesized CS NPs were spherical in shape. The HRTEM images presented that the CS NPs were composed of a segment of small particles (8 nm) and of a second segment of larger particles (80 nm), attributing to the rearrangement of particles after the addition of TPP. The larvicidal activity of CS NPs was confirmed against third instars larvae of A. aegypti. The LC50 value observed was 66.42 mg/L and the corresponding LC90 value was 92.58 mg/L. From this study, it is established that these shell waste materials could be potentially employed for biomedical applications. Keywords: Shrimp shells, Chitosan nanoparticles, Larvicidal activity, Aedes aegypti