Regulation of urea uptake by ammonia in the cyanobacterium Anabaena doliolum

Abstract The urea uptake system was studied with regard to its repression and derepression in the cyanobacterium, Anabaena doliolum . The uptake of urea was energy-dependent and was repressed in ammonia grown cells. Repression of the urea uptake by ammonium did not require ammonium assimilation or de novo protein synthesis, suggesting that ammonium itself was the repressor signal. The derepression of the urea uptake system, however, required de novo protein synthesis and glutamine synthetase activity.     

Chromium accumulation in soil,water and forage samples in automobile emission area

Environmental contamination caused by various pollutants due to automobile emissions is an alarming issue. One important type of the pollutants are heavy metals, including chromium (Cr) added by the exhaust of toxic smoke of vehicles. These pollutants are added to forage crops cultivated near roadsides, soil and irrigation water. However, rare studies have been conducted to infer Cr accumulation near heavy automobile emission areas. This study was conducted to determine Cr concentration in irrigation water, soil and forage. Water, forage and soil samples were collected from area impacted by heavy traffic. Atomic absorption spectrophotometer was used to appraise Cr values in the collected samples. Chromium values ranged from 0.50 to 1.14 mg/kg in water samples and from 0.04 to 2.23 mg/kg in soil samples. It was highest in Zea mays grown soil, whereas minimum in Brassica campestris soil. The Cr values in forages ranged from 0.09 to 1.06 mg/kg. Z. mays observed the highest Cr accumulation, whereas the lowest Cr accrual was noted for B. campestris. The pollution load index (PLI) was the highest for Trifolium alexandrinum, while the lowest for Z. mays. Bio-concentration factor (BCF) ranged from 0.14 to 8.63. The highest BCF was noted for T. alexandrinum, while the lowest for Z. mays. The highest and the lowest daily intake of metal (DIM) was noted for Z. mays at different sites. Health risk index (HRI) was highest for Z. mays and lowest for B. campestris. The results add valuable information on heavy metal accumulation in water, soil and forage samples near to automobile emission area.     

Effect of dietary advanced glycation end products on mouse liver

The exact pathophysiology of non-alcoholic steatohepatitis (NASH) is not known. Previous studies suggest that dietary advanced glycation end products (AGEs) can cause oxidative stress in liver. We aim to study the effects of dietary AGEs on liver health and their possible role in the pathogenesis of NASH. METHODS: Two groups of mice were fed the same diet except the AGE content varied. One group was fed a high AGE diet and the second group was fed a regular AGE diet. Liver histology, alanine aminotransferase, aspartate aminotransferase, fasting glucose, fasting insulin, insulin resistance and glucose tolerance were assessed. RESULTS: Histology revealed that neutrophil infiltration occurred in the livers of the high AGE group at week 26; steatosis did not accompany liver inflammation. At week 39 livers from both groups exhibited macro- or micro-steatosis, yet no inflammation was detected. Higher insulin levels were detected in the regular AGE group at week 26 (P = 0.034), compared to the high AGE group. At week 39, the regular AGE group showed higher levels of alanine aminotransferase (P<0.01) and aspartate aminotransferase (P = 0.02) than those of the high AGE group. CONCLUSIONS: We demonstrate that a high AGE diet can cause liver inflammation in the absence of steatosis. Our results show that dietary AGEs could play a role in initiating liver inflammation contributing to the disease progression of NASH. Our observation that the inflammation caused by high AGE alone did not persist suggests interesting future directions to investigate how AGEs contribute to pro-oxidative and anti-oxidative pathways in the liver.     

Juliflorine: A potent natural peripheral anionic-site-binding inhibitor of acetylcholinesterase with calcium-channel blocking potential, a leading candidate for Alzheimer’s disease therapy

The alkaloid juliflorine (1) from Prosopis juliflora inhibited acetylcholinesterase (AChE, EC 3.1.1.7) and butyrylcholinesterase (BChE, EC 3.1.1.8) enzymes in a concentration-dependent fashion with IC₅₀ values 0.42 and 0.12 μM, respectively. Lineweaver-Burk as well as Dixon plots and their secondary replots indicated that the nature of inhibition was purely of non-competitive type with K_i values 0.4 and 0.1 μM, against AChE and BChE, respectively. By molecular docking studies compound 1 was found to be ideally spaced inside the aromatic gorge of AChE with rings A/B remaining at the top and rings C/D penetrating deep into the gorge, that might be due to the greater hydrophobicity of rings C/D as compared to rings A/B, allowing their simultaneous interaction with the peripheral anionic and quaternary ammonium-binding sites. The 1-AChE complex was found to be stabilized by hydrophobic contacts, hydrogen bonding, and π-π stacking between the compound 1 and amino acid residues of the aromatic gorge of AChE. Amino acid residues Tyr70, Asp72, Tyr121, Trp279, and Tyr334 of the peripheral anionic site (PAS) of AChE were found to be exclusively involved in the hydrophobic contacts with compound 1 that might be responsible for the competitive mode of inhibition. Compound 1 also showed dose-dependent (30-500 μg/mL) spasmolytic and Ca²⁺-channel blocking activities in isolated rabbit jejunum preparations. The cholinesterase inhibitory potential along with calcium-channel blocking activity of compound 1 and safe profile in human neutrophils viable assay could make it a possible drug candidate for Alzheimer’s disease.     

Influence of Frequently Used Chemical Insecticides on Mycoflora Carried by Common Housefly, <Emphasis Type="Italic">Musca domestica</Emphasis> L.

The housefly, Musca domestica L. (Diptera: Muscidae), is a major medical and veterinary insect pest. It serves as a vector of many pathogenic microorganisms causing spoilage of food and diseases in human and animals. Use of chemical insecticides is adapted as a principal tool to manage housefly. Insecticides have many unforeseen ecological consequences including effects on non-target organisms. In the present study, we have assessed the effects of 10 different synthetic insecticides on the growth of mycoflora associated with the external body of the housefly by using poison food technique. Our results reveled that all synthetic insecticides enhanced the growth. Surprisingly, in most of the cases, mycelial growth of fungi was significantly increased at high concentration as compared with lower concentration. This study provides useful information about the dangerous effects of synthetic insecticides on environment by increasing the spread of various non-target pathogenic, mycotoxigenic, and food spoiling fungi, carried by houseflies.     

Protective effects of resveratrol on hepatic ischemia reperfusion injury in streptozotocin-induced diabetic rats

Molecular and Cellular Biochemistry - Resveratrol (RSV) is a natural polyphenolic compound having antioxidant effects. This study was designed to investigate the protective effects of resveratrol...     

Interaction of meropenem with ‘N’ and ‘B’ isoforms of human serum albumin: a spectroscopic and molecular docking study

Carbapenems are used to control the outbreak of β-lactamases expressing bacteria. The effectiveness of drugs is influenced by its interaction with human serum albumin (HSA). Strong binding of carbapenems to HSA may lead to decreased bioavailability of the drug. The non-optimal drug dosage will provide a positive selection pressure on bacteria to develop resistance. Here, we investigated the interaction between meropenem and HSA at physiological pH 7.5 (N-isoform HSA) and non-physiological pH 9.2 (B-isoform HSA). Results showed that meropenem quenches the fluorescence of both ‘N’ and ‘B’ isoforms of HSA (ΔG < 0 and binding constant ~10⁴ M^?1). Electrostatic interactions and van der Waal interactions along with H-bonds stabilized the complex of meropenem with ‘N’ and ‘B’ isoforms of HSA, respectively. Molecular docking results revealed that meropenem binds to HSA near Sudlow’s site II (subdomain IIIA) close to Trp-214 with a contribution of a few residues of subdomain IIA. CD spectroscopy showed a change in the conformation of both the isoforms of HSA upon meropenem binding. The catalytic efficiency of HSA (only N-isoform) on p-nitrophenyl acetate was increased primarily due to a decrease in K_m and an increase in k_cat values. This study provides an insight into the molecular basis of interaction between meropenem and HSA.     

Chloroplast localization of Cry1Ac and Cry2A protein- an alternative way of insect control in cotton

Background

Insects have developed resistance against Bt-transgenic plants. A multi-barrier defense system to weaken their resistance development is now necessary. One such approach is to use fusion protein genes to increase resistance in plants by introducing more Bt genes in combination. The locating the target protein at the point of insect attack will be more effective. It will not mean that the non-green parts of the plants are free of toxic proteins, but it will inflict more damage on the insects because they are at maximum activity in the green parts of plants.

Results

Successful cloning was achieved by the amplification of Cry2A, Cry1Ac, and a transit peptide. The appropriate polymerase chain reaction amplification and digested products confirmed that Cry1Ac and Cry2A were successfully cloned in the correct orientation. The appearance of a blue color in sections of infiltrated leaves after 72 hours confirmed the successful expression of the construct in the plant expression system. The overall transformation efficiency was calculated to be 0.7%. The amplification of Cry1Ac-Cry2A and Tp2 showed the successful integration of target genes into the genome of cotton plants. A maximum of 0.673 μg/g tissue of Cry1Ac and 0.568 μg/g tissue of Cry2A was observed in transgenic plants. We obtained 100% mortality in the target insect after 72 hours of feeding the 2^nd instar larvae with transgenic plants. The appearance of a yellow color in transgenic cross sections, while absent in the control, through phase contrast microscopy indicated chloroplast localization of the target protein.

Conclusion

Locating the target protein at the point of insect attack increases insect mortality when compared with that of other transgenic plants. The results of this study will also be of great value from a biosafety point of view.