Cadmium induced oxidative stress and biochemical responses in cyanobacterium <Emphasis Type="Italic">Nostoc muscorum</Emphasis>

The present study deals with the growth, photosynthesis, oxidative stress and heavy metal accumulation ability of Nostoc muscorum exposed to different levels (2, 4, 8, 16, 20 μM) of cadmium (Cd) concentrations. Growth and photosynthetic pigments i.e., chlorophyll a, carotenoids and phycocyanin were significantly affected by cadmium exposure and inhibition was found to be dose dependent. ¹⁴C-fixation appeared to be more sensitive to Cd than whole cell oxygen evolution. Significant accumulation of Cd in the cells of N. muscorum was noticed after 1 and 2 h of exposure and the accumulation rate was dose and time dependent. Furthermore, the levels of superoxide radicals and hydrogen peroxide (H₂O₂) were found significantly increased by cadmium exposure which in turn accelerated the formation of malondialdehyde (MDA) content, and protein and DNA damage. The selected dose of Cd (20 μM) showed the induction of new polypeptide of ~23.24 kD and the loss of ~37.84 kD and ~69.63 kD whereas the remaining bands were inhibited as compared to control. Significant DNA fragmentation which is a hallmark of programmed cell death (PCD) was also observed in the cells treated with 20 μM of Cd for 48 h. The decrease in proline and total phenol content at 8 and 16 μM suggest that the cells of N. muscorum were not able to mitigate the oxidative stress induced by cadmium exposure. Similarly, the decreased activities of antioxidant enzymes i.e., superoxide dismutase (SOD), catalase (CAT) and peroxidase (POD) also indicates the failure of the antioxidant defense system of N. muscorum to survive at higher concentration (8 and 16 μM) of cadmium.     

Simple,Low-Cost Detection of Candida parapsilosis Complex Isolates and Molecular Fingerprinting of Candida orthopsilosis Strains in Kuwait by ITS Region Sequencing and Amplified Fragment Length Polymorphism Analysis

Candida parapsilosis has now emerged as the second or third most important cause of healthcare-associated Candida infections. Molecular studies have shown that phenotypically identified C. parapsilosis isolates represent a complex of three species, namely, C. parapsilosis, C. orthopsilosis and C. metapsilosis. Lodderomyces elongisporus is another species phenotypically closely related to the C. parapsilosis-complex. The aim of this study was to develop a simple, low cost multiplex (m) PCR assay for species-specific identification of C. parapsilosis complex isolates and to study genetic relatedness of C. orthopsilosis isolates in Kuwait. Species-specific amplicons from C. parapsilosis (171 bp), C. orthopsilosis (109 bp), C. metapsilosis (217 bp) and L. elongisporus (258 bp) were obtained in mPCR. Clinical isolates identified as C. parapsilosis (n = 380) by Vitek2 in Kuwait and an international collection of 27 C. parapsilosis complex and L. elongisporus isolates previously characterized by rDNA sequencing were analyzed to evaluate mPCR. Species-specific PCR and DNA sequencing of internal transcribed spacer (ITS) region of rDNA were performed to validate the results of mPCR. Fingerprinting of 19 clinical C. orthopsilosis isolates (including 4 isolates from a previous study) was performed by amplified fragment length polymorphism (AFLP) analysis. Phenotypically identified C. parapsilosis isolates (n = 380) were identified as C. parapsilosis sensu stricto (n = 361), C. orthopsilosis (n = 15), C. metapsilosis (n = 1) and L. elongisporus (n = 3) by mPCR. The mPCR also accurately detected all epidemiologically unrelated C. parapsilosis complex and L. elongisporus isolates. The 19 C. orthopsilosis isolates obtained from 16 patients were divided into 3 haplotypes based on ITS region sequence data. Seven distinct genotypes were identified among the 19 C. orthopsilosis isolates by AFLP including a dominant genotype (AFLP1) comprising 11 isolates recovered from 10 patients. A rapid, low-cost mPCR assay for detection and differentiation of C. parapsilosis, C. orthopsilosis, C. metapsilosis and L. elongisporus has been developed.     

Regulation of red cell acetylcholinesterase activity in diabetes mellitus

Despite the fact that the significance of red cell membrane acetylcholinesterase (AChE) is unknown, this enzyme of red cell assumes importance since many of its properties have been found to be similar to purified enzyme form of brain tissues. Our investigations on the effect of insulin-dependent diabetes mellitus on red cell AChE revealed that the activity of this enzyme is significantly decreased in diabetes. Insulin treatment restored the activity to the normal level. Solubilization of normal, diabetic and insulin treated diabetic red cell membranes with Triton X-100 (0.2% v/v) caused a general decline in AChE activity, however the per cent decline in activity of diabetic enzyme was lower as compared to normal and insulin treated conditions. From our results it is inferred that the decreased red cell AChE activity in diabetes is due to lesser number of active enzyme molecules and also due to altered membrane microenvironment.     

Phylogenetic distribution of components of the overflow pathway tol-phenylalanine within the enteric lineage of bacteria

The enteric lineage of prokaryotes (traditional enteric bacteria,Aeromonas, andAlteromonas) encompasses closely related genera that share many common character states of aromatic amino acid biosynthesis. For example, they uniformly employ the tightly regulated bifunctional P-protein (chorismate mutase: prephenate dehydratase) to forml-phenylalanine via phenylpyruvate. A second, unregulated pathway to phenylalanine, originally termed the overflow pathway inPseudomonas aeruginosa, consists of a monofunctional chorismate mutase (CM-F) and a cyclohexadienyl dehydratase. The evolution of the overflow pathway has been dynamic in the enteric lineage.Serratia marcescens, Erwinia herbicola, Erwinia amylovora, and several otherErwinia species possess an intact pathway.Salmonella, Klebsiella, andErwinia carotovora possess an incomplete overflow pathway, whileEscherichia, Proteus, Aeromonas, andAlteromonas lack it altogether.     

Erythrocyte membrane acetylcholinesterase in type 1 (insulin-dependent) diabetes mellitus.

1. The erythrocyte membrane acetylcholinesterase activity is significantly (P less than 0.001) decreased in insulin-dependent diabetes mellitus. 2. The activity is negatively correlated (r = -0.97) with the fasting blood glucose level. 3. Insulin treatment restores the activity to normal. 4. The Km of the enzyme for acetylthiocholine iodide was unchanged; however, the Vmax. was decreased, suggesting a decrease in the number of active enzyme molecules in diabetes.