CLIMATE AND AIR QUALITY CO-BENEFITS OF IMPROVING TAXI SYSTEM IN HA LONG CITY, QUANG NINH

Co-benefits of improving taxi system in Ha Long city, Quang Ninh province were studied. Three areas and nine routes in the urban area of Ha Long were selected for conducting this study. Information on the technical specifications of the taxi system was collected by 130 questionnaires. Taxi volume on nine selected routes was determined by vehicle counting. Real-time information on the driving behavior of taxis was obtained by GPS. Collected data were processed to generate input files to run IVE model associated with the base state and 4 selected air pollution control scenarios. Emission factors of air pollutants of the taxi system in Ha Long for these cases were determined. Climate and air quality co-benefits were assessed. Keywords: Co-benefit, Ha Long, IVE model, taxi, air quality, climate, emission factor

At the crossroad of thiamine degradation and biosynthesis

The physiological significance of thiaminase II has escaped our understanding for many years. The recent discovery of a new thiamine salvage pathway shows that this enzyme is involved in the regeneration of precursors for thiamine biosynthesis

Previously Unrecorded Invasive Species and the Unsatisfying Knowledge of Turtle Communities in Northern Vietnam

According to the IUCN, Southeast Asia is the area of the world with the highest number of threatened turtle species. The current status of chelonians is particularly catastrophic in Vietnam. However, there is still a lack of field data to unambiguously support this fact for a few species. To better understand the freshwater turtle diversity and eventually undertake efficient conservation actions, we conducted surveys with local fishers using standardized questionnaires in two independent river systems in northern Vietnam. A total of 112 questionnaires were administered to as many fishers in April and October 2022. We directly observed four sympatric freshwater species (Pelodiscus sinensis, Palea steindachneri, Mauremys sinensis and Sacalia quadriocellata) in Lao Cai and Yen Bai provinces, and two species (Pelodiscus sinensis and Palea steindachneri) in Bac Giang, Hai Duong, Thai Binh, and Hung Yen provinces. Based on the interviews, we added as possible the presence of two other species (Rafetus swinhoei and Pelochelys cantorii) in each of the two study areas. Moreover, we recorded for the first time in Vietnam, two wild individuals of an invasive alien species, the Common snapping turtle (Chelydra serpentina), confirming that the distribution and ecology of turtle species in Vietnam is poorly understood. Furthermore, recent photos (year 2019) of a 38 kg softshell turtle, possibly attributable to Rafetus swinhoei, were recorded from a restaurant in the area. In conclusion, interviews with local fishers have been found to be useful for exploring the likely presence and the local distribution of the various turtle species

A specific inorganic triphosphatase from Nitrosomonas europaea: structure and catalytic mechanism

The CYTH superfamily of proteins is named after its two founding members, the CyaB adenylyl cyclase from Aeromonas hydrophila and the human 25-kDa thiamine triphosphatase. Because these proteins often form a closed β-barrel, they are also referred to as “Triphosphate Tunnel Metalloenzymes” (TTM). Functionally, they are characterized by their ability to bind triphosphorylated substrates and divalent metal ions. These proteins exist in most organisms and catalyze different reactions, depending on their origin. Here we investigate structural and catalytic properties of the recombinant TTM protein from Nitrosomonas europaea (NeuTTM), a 19-kDa protein. Crystallographic data show that it crystallizes as a dimer and that, in contrast to other TTM proteins, it has an open β-barrel structure. We demonstrate that NeuTTM is a highly specific inorganic triphosphatase, hydrolyzing tripolyphosphate (PPPi) with high catalytic efficiency in the presence of Mg2+. These data are supported by native mass spectrometry analysis showing that the enzyme binds PPPi (and Mg-PPPi) with high affinity (Kd < 1.5 μM), while it has a low affinity for ATP or thiamine triphosphate. In contrast to Aeromonas and Yersinia CyaB proteins, NeuTTM has no adenylyl cyclase activity, but it shares several properties with other enzymes of the CYTH superfamily, e.g. heat-stability, alkaline pH optimum and inhibition by Ca2+ and Zn2+ ions. We suggest a catalytic mechanism involving a catalytic dyad formed by K52 and Y28. The present data provide the first characterization of a new type of phosphohydrolase (unrelated to pyrophosphatases or exopolyphosphatases), able to hydrolyze inorganic triphosphate with high specificity

An alternative role of FoF1-ATP synthase in Escherichia coli: synthesis of thiamine triphosphate

In E. coli, thiamine triphosphate (ThTP), a putative signaling molecule, transiently accumulates in response to amino acid starvation. This accumulation requires the presence of an energy substrate yielding pyruvate. Here we show that in intact bacteria ThTP is synthesized from free thiamine diphosphate (ThDP) and Pi, the reaction being energized by the proton-motive force (Dp) generated by the respiratory chain. ThTP production is suppressed in strains carrying mutations in F1 or a deletion of the atp operon. Transformation with a plasmid encoding the whole atp operon fully restored ThTP production, highlighting the requirement for FoF1-ATP synthase in ThTP synthesis. Our results show that, under specific conditions of nutritional downshift, FoF1-ATP synthase catalyzes the synthesis of ThTP, rather than ATP, through a highly regulated process requiring pyruvate oxidation. Moreover, this chemiosmotic mechanism for ThTP production is conserved from E. coli to mammalian brain mitochondria