Structure-Function Analysis of Human TYW2 Enzyme Required for the Biosynthesis of a Highly Modified Wybutosine (yW) Base in Phenylalanine-tRNA

Posttranscriptional modifications are critical for structure and function of tRNAs. Wybutosine (yW) and its derivatives are hyper-modified guanosines found at the position 37 of eukaryotic and archaeal tRNAPhe. TYW2 is an enzyme that catalyzes α-amino-α-carboxypropyl transfer activity at the third step of yW biogenesis. Using complementation of a ΔTYW2 strain, we demonstrate here that human TYW2 (hTYW2) is active in yeast and can synthesize the yW of yeast tRNAPhe. Structure-guided analysis identified several conserved residues in hTYW2 that interact with S-adenosyl-methionine (AdoMet), and mutation studies revealed that K225 and E265 are critical residues for the enzymatic activity. We previously reported that the human TYW2 is overexpressed in breast cancer. However, no difference in the tRNAPhe modification status was observed in either normal mouse tissue or a mouse tumor model that overexpresses Tyw2, indicating that hTYW2 may have a role in tumorigenesis unrelated to yW biogenesis

Impact of local recharge on arsenic concentrations in shallow aquifers inferred from the electromagnetic conductivity of soils in Araihazar, Bangladesh

The high-degree of spatial variability of dissolved As levels in shallow aquifers of the Bengal Basin has been well documented but the underlying mechanisms remain poorly understood. We compare here As concentrations measured in groundwater pumped from 4700 wells <22 m (75 ft) deep across a 25 km2 area of Bangladesh with variations in the nature of surface soils inferred from 18,500 measurements of frequency domain electromagnetic induction. A set of 14 hand auger cores recovered from the same area indicate that a combination of grain size and the conductivity of soil water dominate the electromagnetic signal. The relationship between pairs of individual EM conductivity and dissolved As measurements within a distance of 50 m is significant but highly scattered (r2 = 0.12; n = 614). Concentrations of As tend to be lower in shallow aquifers underlying sandy soils and higher below finer-grained and high conductivity soils. Variations in EM conductivity account for nearly half the variance of the rate of increase of As concentration with depth, however, when the data are averaged over a distance of 50 m (r2 = 0.50; n = 145). The association is interpreted as an indication that groundwater recharge through permeable sandy soils prevents As concentrations from rising in shallow reducing groundwater

Internet-based atlas of the primate spinal cord

In 2009, we reported an online brain atlas of the common marmoset (Callithrix jacchus) at http://marmoset-brain.org:2008. Here we report new digital images of the primate spinal cord sections added to the website. We prepared histological sections of every segment of the spinal cord of the common marmoset, rhesus monkey and Japanese monkey with various staining techniques. The sections were scanned with Carl Zeiss MIRAX SCAN at light microscopic resolution. Obtained digital data were processed and converted into multi-resolutionary images with Adobe Photoshop and Zoomify Design. These images of the primate spinal cords are now available on the web via the Internet

Assessing the impact of 1498 Meio earthquake and tsunami along the Enshu-nada coast, central Japan using coastal geology

The AD 1498 Meio earthquake (M8.2 similar to 8.4) that occurred along the eastern Nankai trough, and the tsunami generated by the earthquake, induced major geomorphological and social changes along the Pacific coast of central Japan. Geological coring along the palaeochannel of the Hamana River, southern Shizuoka Prefecture, revealed that its river mouth was abruptly closed followed by a rapid change from river to marsh environment at the end of the 15th century. It is suggested that mass transport of sediments by the Meio tsunami forced the closure of the river mouth. The latter environmental change happened synchronously with the sudden decline of a famous port town, Hashimoto, formerly flourishing along the middle reach of Hamana River. Closure of the water route connecting Hashimoto with the Pacific Ocean potentially led to the decline and abandonment of the port town