A natural fusion of flavodiiron,rubredoxin, and rubredoxin oxidoreductase domains is a self-sufficient water-forming oxidase of Trichomonas vaginalis

Microaerophilic pathogens such as Giardia lamblia, Entamoeba histolytica, and Trichomonas vaginalis have robust oxygen consumption systems to detoxify oxygen and maintain intracellular redox balance. This oxygen consumption results from H₂O-forming NADH oxidase (NOX) activity of two distinct flavin-containing systems: H₂O-forming NOXes and multicomponent flavodiiron proteins (FDPs). Neither system is membrane bound, and both recycle NADH into oxidized NAD⁺ while simultaneously removing O₂ from the local environment. However, little is known about the specific contributions of these systems in T. vaginalis. In this study, we use bioinformatics and biochemical analyses to show that T. vaginalis lacks a NOX–like enzyme and instead harbors three paralogous genes (FDPF1–3), each encoding a natural fusion product between the N-terminal FDP, central rubredoxin (Rb), and C-terminal NADH:Rb oxidoreductase domains. Unlike a “stand-alone” FDP that lacks Rb and oxidoreductase domains, this natural fusion protein with fully populated flavin redox centers directly accepts reducing equivalents of NADH to catalyze the four-electron reduction of oxygen to water within a single polypeptide with an extremely high turnover. Furthermore, using single-particle cryo-EM, we present structural insights into the spatial organization of the FDP core within this multidomain fusion protein. Together, these results contribute to our understanding of systems that allow protozoan parasites to maintain optimal redox balance and survive transient exposure to oxic conditions.     

Characterization of archaeal symbionts of sponges from the coral reef ecosystems of the Gulf of Mannar,Southeast coast of India

Sponges accommodate a diverse group of microorganisms with varied metabolic capabilities. The bacterial associates of sponges are widely studied while our understanding of archaeal counterparts is scanty. In the present study, we report the archaeal associates of two sponges, Pseudoceratina purpurea (NCBI barcode: KX454492) and Cinachyra sp. (NCBI barcode: KX454495), found in the coral reef ecosystems of Gulf of Mannar, India. Archaea in the water column was predominated by members of class Halobacteria of Phylum Euryarchaeota (97%) followed by a minor fraction (3%) of Nitrosopumilus sp. of phylum Thaumarchaeota. Interestingly, Thaumarchaeota was identified as the sole archaeal population associated with the two sponges studied, among which Nitrosopumilus sp. occuppied 80 and 100% of the sequences in the clone library of P. purpurea and Cinachyra sp. respectively. Other archaea found in the P. purpurea were Nitrososphaera (10%) and unclassified ones (10%). The study identified Nitrosopumilus sp. as a unique symbiotic archaeon of sponges, P. purpurea and Cinachyra sp. The existence of host driven factors in selecting specific associates from a diverse group of archaea in the environment may need further investigations.     

Exploration and local utilization of medicinal vegetation naturally grown in the Deusai plateau of Gilgit,Pakistan

In the study area, the traditional knowledge regarding the uses of local wild medicinal plants for the health care of human and domestic animals is totally in hold of old people. The young ones are unaware about such an indispensable practices. The objective of the current study was to transfer this sort of precious knowledge from old members of the community to young generations in documented form.     

Fulvic Acid Prevents Chromium-induced Morphological,Photosynthetic, and Oxidative Alterations in Wheat Irrigated with Tannery Waste Water

Journal of Plant Growth Regulation - Rapid industrialization is potentially contaminating the environment. Tannery is one of the industries producing very high amount of effluents, having a...     

In vitro inhibition of human erythrocyte acetylcholinesterase (EC3.1.1.7) by an antineoplastic drug methotrexate

This work addresses the kinetic analysis of the interaction of methotrexate (MTX) with human erythrocyte membrane-bound acetylcholinesterase (AChE, EC 3.1. 1.7). It was found that the MTX effect was independent of time of incubation with AChE before the addition of substrate which proves its reversible action. The IC₅₀ was determined, by three methods, to be 0.73 mM. The Michaelis-Menten constant (K_s) for the hydrolysis of acetylthiocholine iodide (ASCh) by AChE was 0.13 mM in the control system, a value decreased by 30–61% in the MTX treated systems. The V_max was 1.27tmole/min/mg protein for the control system while it was decreased by 44–77% in the MTX treated systems. The Linexveaver-Buck plot, Dixon plot, and their secondary replots indicated that the nature of the inhibition was of the linear mixed type, i.e. uncompetitive and noncompetitive. The values of K_i(slope) and K_I(tntecept) were estimated as 1.67 and 0.34 mM, respectively.Abbreviations AChE acetylcholinesterase - ASCh acetylthiocholine - K_s Michaelis-Menten constant - V_max the limiting maximal velocity - K_i inhibition constant - MTX methotrexate     

Phylogeny of six oligohymenophoreans (Protozoa, Ciliophora) inferred from small subunit rRNA gene sequences

The small subunit rRNA (SSrRNA) genes of six marine oligohymenophoreans, namely Uronemella filificum , Schizocalyptra sp.-WYG07060701, Schizocalyptra aeschtae , Pleuronema sinica , P. czapikae and Paratetrahymena sp., were sequenced. Phylogenetic trees were constructed with four different methods to assess the inter- and intrageneric relationships among the scuticociliates and the phylogenetic assignment of the order Loxocephalida. The SSrRNA phylogeny indicates that: (i) Paratetrahymena is most closely related to Cardiostomatella ; (ii) the order Loxocephalida and the family Uronematidae both appear to be polyphyletic; (iii) the order Philasterida is a well-defined taxon; (iv) Cyclidium porcatum falls outside the order Pleuronematida in all analyses; (v) the validity of the genus Uronemella is confirmed; (vi) Schizocalyptra is a member of the family Pleuronematidae. Furthermore, the predicted secondary structures of the variable region 4 of the SSrRNA gene sequences show that the size of the terminal bulge in Helix E23–7 is probably different for the orders Philasterida and Pleuronematida. Also, compared to Uronema and Homalogastra , Uronemella has distinct patterns in Helices E23–1, E23–7, E23–8 and E23–9.     

Biotransformation of dehydroepiandrosterone with Macrophomina phaseolina and β-glucuronidase inhibitory activity of transformed products

The biotransformation of dehydroepiandrosterone (1) with Macrophomina phaseolina was investigated. A total of eight metabolites were obtained which were characterized as androstane-3,17-dione (2), androst-4-ene-3,17-dione (3), androst-4-ene-17β-ol-3-one (4), androst-4,6-diene-17β-ol-3-one (5), androst-5-ene-3β,17β-diol (6), androst-4-ene-3β-ol-6,17-dione (7), androst-4-ene-3β,7β,17β-triol (8), and androst-5-ene-3β,7α,17β-triol (9). All the transformed products were screened for enzyme inhibition, among which four were found to inhibit the β-glucuronidase enzyme, while none inhibited the α-chymotrypsin enzyme.