Screening method for the detection of uptake hydrogenase activity of Rhizobium leguminosarum bacteroids

Abstract A method has been developed for screening Rhizobium leguminosarum wild-type strains and mutants for uptake hydrogenase (Hup) activity, using H₂-dependent methylene blue reduction. For this purpose, a simple device has been constructed which allows the simultaneous screening of 6 strains and 6 controls. Bacteroids of R. leguminosarum isolated from pea root nodules were suspended in buffer containing methylene blue and inhibitors of dehydrogenases. The suspensions were first sparged with argon (to remove oxygen) and then with hydrogen.     

A scaffold replacement approach towards new sirtuin 2 inhibitors

Sirtuins (SIRT1–SIRT7) are an evolutionary conserved family of NAD⁺-dependent protein deacylases regulating the acylation state of ε-N-lysine residues of proteins thereby controlling key biological processes. Numerous studies have found association of the aberrant enzymatic activity of SIRTs with various diseases like diabetes, cancer and neurodegenerative disorders. Previously, we have shown that substituted 2-alkyl-chroman-4-one/chromone derivatives can serve as selective inhibitors of SIRT2 possessing an antiproliferative effect in two human cancer cell lines. In this study, we have explored the bioisosteric replacement of the chroman-4-one/chromone core structure with different less lipophilic bicyclic scaffolds to overcome problems associated to poor physiochemical properties due to a highly lipophilic substitution pattern required for achieve a good inhibitory effect. Various new derivatives based on the quinolin-4(1H)-one scaffold, bicyclic secondary sulfonamides or saccharins were synthesized and evaluated for their SIRT inhibitory effect. Among the evaluated scaffolds, the benzothiadiazine-1,1-dioxide-based compounds showed the highest SIRT2 inhibitory activity. Molecular modeling studies gave insight into the binding mode of the new scaffold-replacement analogues.     

Individual tree context and contrast dictate tree physiological features and arthropod biodiversity patterns across multiple trophic levels

1. The present study tested the hypothesis that tree context (natural, semi-natural or planted) and contrast (height of surrounding vegetation) affect tree physiological characters (leaf size, nutrient content, and stress-related factors), and also alter the arthropod biodiversity patterns either directly or indirectly. 2. Arthropods were collected from tree canopies using chemical fogging from the ecologically important South African native tree Podocarpus elongatus. 3. Low contrast trees had significantly larger leaves than those in high contrast environments and harboured an overall higher richness, abundance, and biomass of arthropods, although this was guild-dependent. 4. Trees in natural contexts had less foliar δ¹³C, suffered less from artificial nitrogen enrichment, and harboured significantly higher herbivore and predator arthropod richness and unique assemblages, compared with planted trees. 5. Semi-natural trees supported natural levels of arthropod richness, although these were mostly generalist species. 6. Tree context and contrast can therefore dictate associated biota at multiple trophic levels and native trees may fail to maintain natural biodiversity in transformed landscapes.     

Perceptions of Veterinarians in British Columbia of Cat Management Strategies to Reduce Cat Overpopulation and Impacts on Wildlife Populations

ABSTRACT

Free-roaming cats present a multidisciplinary challenge for wildlife conservation and feline welfare. Veterinary professionals are critical stake-holders in the issue of free-roaming cats, making it imperative that their attitudes and perspectives are well understood. In this study, we conducted an electronic survey of veterinarians practicing across British Columbia to evaluate their perceptions of 1) whether cat overpopulation is a concern, 2) the impacts of cats on wildlife, and 3) alternative management strategies for dealing with cat overpopulation. Of the 389 respondents, 56% agreed that cat overpopulation was a local problem, and 91% agreed that veterinarians play a role in reducing cat overpopulation. Veterinarians in rural communities had a greater involvement in cat overpopulation and perceived it as more problematic than their urban colleagues. The majority (70%) of veterinarians reported that they performed early-age sterilization, supported the principle of low-cost spay-neuter services (67%), and 65% of them were involved in these services. Just over half (54%) of respondents reported that they provide permanent identification to cats, typically offering both microchips and tattoos. Veterinarians were less cohesive on their perceptions of the impact of free-roaming cats on wildlife: 53% agreed that after habitat loss cats are one of the most significant, direct causes of bird and wildlife mortality, while 30% were neutral and 17% disagreed. Fifty-six percent of veterinarians felt that keeping cats indoors would be one of the most effective strategies to reduce cat impacts on wildlife, but they also felt that public education programs and low-cost spay-neuter programs would be effective and more popular with cat owners. Most veterinarians (79%) recommended against unsupervised outdoor access, citing safety and disease risks. Rodent control was the most common reason for not recommending an indoor lifestyle. Overall, our survey results suggest that veterinarians are committed participants in the prevention of cat overpopulation. Conservationists need to focus on increased engagement with veterinarians regarding the impact of cats on wildlife.     

Hydrogen bonds in Zif268 proteins – a theoretical perspective

The aim of the work was to elucidate the presence of different hydrogen bond (H-bond) in five Zif268 proteins (1A1F, 1A1G, 1A1H, 1A1I and 1A1K). For this purpose, we have performed the QM/MM and molecular dynamics (MD) studies, the results of which reveal that H-bonds depend on the amino acid sequence and orientation of the H-bond donor atoms. Further, high specificity of Arg and Asn is observed for guanine and adenine, respectively. Furthermore, both conventional and non-conventional hydrogen bond also exists in the proteins, among them N–H?O H-bonds are the strongest. Besides, the non-conventional bonds play a role in the protein folding and DNA stacking. From the QSAR properties, amino acids such as asparagine and aspartic acids are the major reactive sites in the Zif268 protein. The electron affinities of Zif268 proteins are high, so the charge transfer occurs from the DNA to the protein molecules. NBO analysis indicates the majority of charge transfer occurs from DNA to the corresponding anti-bonding orbital of the peptides. Root mean square deviation and R_g (radius of gyration) show that 1A1F is more compact and in native state during MD simulation. The minimum R_g leads to the large number of hydrogen bonds formation in 1A1F. Higher solvent accessible surface area in 1A1I indicates that the cavity inside the protein is large.     

Arundo micrantha,a new reed species for Italy,threatened in the freshwater habitat by the congeneric invasive A. donax

Arundo micrantha Lam., a reed species from southern Mediterranean area, has found in Sardinia. Its presence represents the first record for Italy and the third one for western Europe. Investigations on distribution and ecology of the Sardinian population have been carried out, with special focusing on synecology of the species. A. micrantha has found in 40 localities mainly distributed along temporary streams and permanent rivers in the central and southern part of the island. Most of Sardinian populations occurs on alluvial soils in Thermomediterranean bioclimatic context. The autonomy of Sardinian phytocoenoses was characterized with the definition of exclusive floristic taxa, biological and chorological elements, and syndinamic relationships with other assemblages. Comparing the community with other reed beds from the Mediterranean basin, a marked floristic differentiation arose between the phytocoenoses characterized by autochthonous Arundo species and those dominated by the invasive Arundo donax. Finally, management activities are proposed to ensure the conservation of this threatened autochthonous plant community in freshwater habitat.     

Comparative Network Biology Discovers Protein Complexes That Underline Cellular Differentiation in Anabaena sp.

The filamentous cyanobacterium Anabaena sp. PCC 7120 can differentiate into heterocysts to fix atmospheric nitrogen. During cell differentiation, cellular morphology and gene expression undergo a series of significant changes. To uncover the mechanisms responsible for these alterations, we built protein–protein interaction (PPI) networks for these two cell types by cofractionation coupled with mass spectrometry. We predicted 280 and 215 protein complexes, with 6322 and 2791 high-confidence PPIs in vegetative cells and heterocysts, respectively. Most of the proteins in both types of cells presented similar elution profiles, whereas the elution peaks of 438 proteins showed significant changes. We observed that some well-known complexes recruited new members in heterocysts, such as ribosomes, diflavin flavoprotein, and cytochrome c oxidase. Photosynthetic complexes, including photosystem I, photosystem II, and phycobilisome, remained in both vegetative cells and heterocysts for electron transfer and energy generation. Besides that, PPI data also reveal new functions of proteins. For example, the hypothetical protein Alr4359 was found to interact with FraH and Alr4119 in heterocysts and was located on heterocyst poles, thereby influencing the diazotrophic growth of filaments. The overexpression of Alr4359 suspended heterocyst formation and altered the pigment composition and filament length. This work demonstrates the differences in protein assemblies and provides insight into physiological regulation during cell differentiation.