The Methylcitrate Cycle and Its Crosstalk with the Glyoxylate Cycle and Tricarboxylic Acid Cycle in Pathogenic Fungi.

In fungi, the methylcitrate cycle converts cytotoxic propionyl-coenzyme A (CoA) to pyruvate, which enters gluconeogenesis. The glyoxylate cycle converts acetyl-CoA to succinate, which enters gluconeogenesis. The tricarboxylic acid cycle is a central carbon metabolic pathway that connects the methylcitrate cycle, the glyoxylate cycle, and other metabolisms for lipids, carbohydrates, and amino acids. Fungal citrate synthase and 2-methylcitrate synthase as well as isocitrate lyase and 2-methylisocitrate lyase, each evolved from a common ancestral protein. Impairment of the methylcitrate cycle leads to the accumulation of toxic intermediates such as propionyl-CoA, 2-methylcitrate, and 2-methylisocitrate in fungal cells, which in turn inhibits the activity of many enzymes such as dehydrogenases and remodels cellular carbon metabolic processes. The methylcitrate cycle and the glyoxylate cycle synergistically regulate carbon source utilization as well as fungal growth, development, and pathogenic process in pathogenic fungi.

Mitochondrial fission protein MoFis1 mediates conidiation and is required for full virulence of the rice blast fungus Magnaporthe oryzae.

The mitochondrial fission protein Fis1 regulates yeast mitochondrial fission and is required for ethanol-induced mitochondrial fragmentation and apoptosis. To examine the function of Fis1 in a plant pathogenic fungus, we cloned the MoFIS1 gene, a homolog of Saccharomyces cerevisiae FIS1, from Magnaporthe oryzae and characterized its function by targeted gene deletion and mutant phenotypic analysis. MoFIS1 deletion mutants were unaltered in conidial germination, appressorium formation, and mating tests, but were severely defective in colony growth, conidiation, virulence on rice and barley, growth under nitrogen and glucose deficiency, and growth under osmotic stress. Blast lesions on rice leaves caused by the ΔMofis1 strain were significantly reduced, were non-proliferating, and were less coalesced as compared to the highly coalesced and proliferating lesions resulting from infection with the wild-type strain. The defects in growth, conidiation, and virulence of the mutant were restored in a complementation strain of ΔMofis1. A MoFis1-GFP fusion protein co-localized with Mitotracker red in mitochondria. These results show that MoFIS1 encodes a mitochondrial protein that regulates fungal growth, conidiation, and virulence in M. oryzae.

Disruption and molecular characterization of calpains-related (MoCAPN1, MoCAPN3 and MoCAPN4) genes in Magnaporthe oryzae.

Calpains are intracellular, cysteine proteases found in plants, animals and fungi functioning as signal transduction components in different cellular pathways including sporulation and alkaline adaptation in fungi. Calpains-related MoCAPN1 (MGG_14872), MoCAPN3 (MGG_15810) and MoCAPN4 (MGG_04818) genes from Magnaporthe oryzae genome which are 2604, 3513 and 771-bp in length and encoding identical proteins of 867, 1170 and 256 amino acids were functionally characterized for different phenotypes through gene disruption method. All the mutants except those for MoCAPN1 showed normal phenotypes. In pathogenicity test, the mutants did not lead to any visible changes in phenotypes causing similar blast lesions on blast susceptible rice and barley leaves as those of the Guy-11 strain suggesting no major role in pathogenicity. Germ tubes formation, appressorium formation, mycelium radial growth and mating with 2539 strain were indistinguishable among the mutants and Guy-11 strains. Cell wall integrity (congo red) test, stress response under chemical pressure (ZnSO4, CuSO4 and CdCl2), osmotic and oxidative (NaCl and H2O2) stress response, growth response on glucose and nitrogen deficient media resulted in similar results in the mutants and Guy-11 strains. However, mutants for ΔMoCAPN1 gene produced reduced (0.57±0.15B and 0.54±0.05B) conidia compared to that (1.69±0.13A) of the Guy-11 strain showing its involvement in conidiation.

Treatment of ingrown toe nail-comparison of phenolization after partial nail avulsion and partial nail avulsion alone.

BACKGROUND: Ingrown toe nail is common problem presenting to the surgeon. Partial Nail avulsion only results in recurrence of the ingrown toe nail. The aim of this study was too see the effect of phenolization in preventing recurrence after partial nail avulsion. METHODS: This was a randomized controlled trial carried out at Department of Surgery, Pakistan Institute of Medical Sciences, Islamabad. This study included 100 patients (50 in each group) with ingrown toe nail presented from November 2009 to October 2010. This study compared the application of phenol after partial avulsion with partial avulsion alone in the treatment of ingrown toe nail. RESULTS: Sixty-nine percent of the patients were males and 31 % were female. The mean age in both groups was 18 years. Patient in the partial nail avulsion with application of phenol group had less pain as compared to patient with partial nail avulsion group only. Our study has shown that patient in phenol group had less post operative infection, spike formation and recurrence as compared to wedge resection group only. CONCLUSION: Partial nail avulsion with phenolization is better than nartial nail avulsion only for the management of the in-growing toe nail.

Multifunction of autophagy-related genes in filamentous fungi.

Autophagy (macroautophagy), a highly conserved eukaryotic mechanism, is a non-selective degradation process, helping to maintain a balance between the synthesis, degradation and subsequent recycling of macromolecules to overcome various stress conditions. The term autophagy denotes any cellular process which involves the delivery of cytoplasmic material to the lysosome for degradation. Autophagy, in filamentous fungi plays a critical role during cellular development and pathogenicity. Autophagy, like the mitogen-activated protein (MAP) kinase cascade and nutrient-sensing cyclic AMP (cAMP) pathway, is also an important process for appressorium turgor accumulation in order to penetrate the leaf surface of host plant and destroy the plant defense. Yeast, an autophagy model, has been used to compare the multi-valued functions of ATG (autophagy-related genes) in different filamentous fungi. The autophagy machinery in both yeast and filamentous fungi is controlled by Tor kinase and both contain two distinct phosphatidylinositol 3-kinase complexes. In this review, we focus on the functions of ATG genes during pathogenic development in filamentous fungi.

Two-port laparoscopic cholecystectomy--a new technique.

Laparoscopic cholecystectomy is now the procedure of choice in all the gall bladder diseases and there is increase in the skills of surgeons with newer equipment. Normally the laparoscopic cholecystectomy is performed by using four ports or three ports. Two ports laparoscopic cholecystectomy is rarely performed as it demands greater expertise and skills. Also this technique is less expensive and less scar formation than four port laparoscopic cholecystectomy. We present a case of a middle aged female who underwent successfully laparoscopic cholecystectomy by using only two ports.