Toxic metal ion in seafood: Meta-analysis of human carcinogenic and non-carcinogenic threat assessment,a geomedical study from Dhamra and Puri,Odisha

The investigation revealed the adverse health threats on human beings from toxic metals via ingestion of seafood from two contaminated sites in Odisha. Bioaccumulation through food chain was presented as tissue metal concentrations. The non-carcinogenic and carcinogenic health hazards were estimated by Target Hazard Quotient (THQ) and Target Cancer Risk (TCR) following USEPA referred safe metal intake limit. THQ of Metals like Mn, Ni, Cd, Pb in both sites showed >1, indicating a severe non carcinogenic health threat to humans from the investigated metals. THQ of Cu, Zn, Fe, Cr and Hg showed < 1, implying the least possible deleterious health effects. Cr was the most significant carcinogenic pollutant in both sites. The marine fish consumption of Dhamra site might cause extra 7 cases of cancer per 10000 populations due to higher Cr level (cancer risk 6.7 × 10^?3). Carcinogenic risk of Ni and Pb were below the tolerable range of 10E-4. The presence of Cd in sea foods elevated cancer risks in both sites. The metal pollution index (MPI) indicated, the highest toxic metal bio accumulation was contributed by Arius arius species. Ilisha megaloptera and Lates calcarifer from Dhamra and Puri showed highest hazard index (HI) suggesting unaccountable non-carcinogenic health threat.     

RecD plays an essential function during growth at low temperature in the antarctic bacterium Pseudomonas syringae Lz4W

The Antarctic psychrotrophic bacterium Pseudomonas syringae Lz4W has been used as a model system to identify genes that are required for growth at low temperature. Transposon mutagenesis was carried out to isolate mutant(s) of the bacterium that are defective for growth at 4 degrees but normal at 22 degrees . In one such cold-sensitive mutant (CS1), the transposon-disrupted gene was identified to be a homolog of the recD gene of several bacteria. Trans-complementation and freshly targeted gene disruption studies reconfirmed that the inactivation of the recD gene leads to a cold-sensitive phenotype. We cloned, sequenced, and analyzed approximately 11.2 kbp of DNA from recD and its flanking region from the bacterium. recD was the last gene of a putative recCBD operon. The RecD ORF was 694 amino acids long and 40% identical (52% similar) to the Escherichia coli protein, and it could complement the E. coli recD mutation. The recD gene of E. coli, however, could not complement the cold-sensitive phenotype of the CS1 mutant. Interestingly, the CS1 strain showed greater sensitivity toward the DNA-damaging agents, mitomycin C and UV. The inactivation of recD in P. syringae also led to cell death and accumulation of DNA fragments of approximately 25-30 kbp in size at low temperature (4 degrees ). We propose that during growth at a very low temperature the Antarctic P. syringae is subjected to DNA damage, which requires direct participation of a unique RecD function. Additional results suggest that a truncated recD encoding the N-terminal segment of (1-576) amino acids is sufficient to support growth of P. syringae at low temperature.     

Infrared-to-visible conversion in strontium sulphate through a defect-based infrared stimulated visible emission phenomenon

Strontium sulphate (SrSO₄) is a defect-based photoluminescence material, generally used in thermoluminescence applications, and has been studied for infrared (IR) stimulated visible emission. The SrSO₄ particles were synthesized using a precipitation method. The orthorhombic phase of SrSO₄ was confirmed from the X-ray diffraction pattern and the formation of micron-sized particles was authenticated from field emission scanning electron micrographs. The elemental composition of oxygen and strontium was determined using energy-dispersive X-ray analysis measurement that confirmed the presence of $V_O^{••}$ and $V_{\mathit{Sr}}^{\prime \prime }$ intrinsic defects in the material. Photoluminescence investigations showed the presence of various defect bands in the band gap giving rise to intrinsic luminescence in SrSO₄. The emission in the visible region was attributed to the defect band arising due to $V_O^{••}$. Photoluminescence lifetime measurement confirmed the presence of stable defect states with a lifetime in microseconds. The SrSO₄ sample was tested using IR lasers and a red–orange emission spot was observed from the powder sample when excited with IR lasers. The underlying principle for IR-to-visible conversion in the material is a defect-mediated phenomenon that has been described through the energy level diagram of the material.