Lactonase-expressing Lactobacillus plantarum NC8 attenuates the virulence factors of multiple drug resistant Pseudomonas aeruginosa in co-culturing environment

Pseudomonas aeruginosa possesses an arcade of both cell-associated and extracellular cytotoxic virulence factors which are regulated by a multi-component quorum sensing system. Many research studies report success of lactonase in combating the pathogenicity of P. aeruginosa but delivery of lactonase remains a challenge. The present study aims at developing a delivery vehicle for lactonase. Lactobacillus plantarum NC8 was used as host for aiiA (Bacillus thuringiensis 4A3 lactonase gene) using pSIP409 expression vector. pSIP409: aiiA construct was stably maintained in L. plantarum NC8. Co-culturing of multi-drug resistant (MDR) clinical isolates of P. aeruginosa and PAO1 with recombinant L. plantarum NC8 led to significant reduction (p < 0.001) in extracellular virulence factors like pyocyanin, protease, elastase and rhamnolipids in P. aeruginosa and also showed significant reduction in adhesion of P. aeruginosa strains to uroepithelial cells in vitro. This study shows the heterologous expression of AiiA lactonase in L. plantarum NC8. Co-culturing of lactonase expressing L. plantarum NC8 with MDR P. aeruginosa strains led to attenuation of their virulence significantly. These results underscore the potential application of recombinant L. plantarum NC8 with anti-quorum sensing properties to control infections caused by multidrug resistant P. aeruginosa.     

Metamorphosis of the central nervous system ofDrosophila melanogaster Meigen (Diptera: Drosophilidae) during pupation

We studied the metamorphosis of the central nervous system (CNS) and neighbouring muscles ofDrosophila melanogaster (Diptera: Drosophilidae) during pupation by transmission electron microscopy (TEM). The age of white pupa was assumed to be 0 h and the process of metamorphosis was monitored, onward between 6 and 96 h at 25°C. The profiles in the neuropil showed degeneration at 6 h and its extent increased by 12 h. The presence of glycogen in some of these profiles indicated their larval character. Between 12–18 h, the neuronal profiles became separated from one another, the intervening space was filled with extracellular fluid, and some of the larval synapses degenerated. Synaptic vesicles started reappearing around 18 h and synapses were detectable by 24 h. Neuronal processes compactly filled the neuropil by 65 h and the maturation of synapses continued until 86 h. The degeneration of profiles in the neuropil was found to be bimodal, peaking at 12 and 42 h, and that of cortical cells was unimodal with a peak at 42 h. The number of neuronal profiles increased with the development time, indicating that more branching of neuronal profiles occurs in neuropils as the metamorphosis progresses. Average number of synapses per unit area (or volume) is minimum at 18 h and maximum at 72 h, when the average number of synapse per axon profile is 0.54. Because 2 axon profiles share one synapse, a value close to 0.5 for monad synapses shows that, on an average, each axon profile at least makes one synapse at this stage of development. Subsequently, there is more than 75% of reduction in the number of synapses during 73 and 78 h. In muscles, vacuoles suggesting histolysis appeared by 6 h. Their ultrastructure became deranged between 12–18 h and myoblasts were found to be present since 8 h. Except for a few muscles in the thorax, such as larval oblique muscles and pharyngeal muscles, most of the muscles in the head and thorax lost all the ultrastructural details and histolyzed by 18 h. Around 38 h, imaginai muscles were detectable, and well-developed muscles were found by 55 h. However, myofibrils continued to be added laterally to the preformed muscles even at 96 h. Electron-dense mitochondria (EDMITs) were found in the neuropil, cortex and muscles of pupa, along with mitochondria of characteristic shape and normal appearance. These EDMITs often occurred in large clusters of more than 100, at times near the surface of the tissue. A few of these were enclosed in vacuoles and were darker than the rest of the EDMITs and normal looking mitochondria. Histochemistry with diaminobenzidine showed the presence of cytochrome c and marker enzyme cytochrome oxidase, both in EDMITs and normal mitochondria. EDMITs were not found to be present in any tissue of the adultDrosophila. A preliminary report of the work was presented at the International Conference on Neurobiology at Goa in 1991 and appeared inNervous Systems, Principles of Design and Function (ed.) R N Singh (New Delhi: Wiley Eastern) pp 91–105 (1992).     

Chemical modification of alpha-chymotrypsin for obtaining high transesterification activity in low water organic media

Alpha-chymotrypsin was made more hydrophilic by modifying 11 (out of 16) ε-amino groups with pyromellitic dianhydride. The hydrophilic preparation was precipitated with n-propanol. This preparation gave significantly higher initial rates at the optimum a_w (127.51 nmol mg^?1 min^?1 in n-octane and 21.30 nmol mg^?1 min^?1 in acetonitrile at a_w=0.33) compared with the lyophilized preparation (53.50 nmol mg^?1 min^?1 in n-octane and 0.26 nmol mg^?1 min^?1 in acetonitrile at a_w=0.97). FT-IR showed that the precipitate of modified alpha-chymotrypsin has a higher content of alpha-helices and beta-sheets compared to the lyophilized powder.     

Clinical and biochemical effects of aflatoxin in feed ration of chicks

Aflatoxin carcinogenesis appears to relate to multiple factors. This includes bulky adduct formation at DNA guanine N-7. The process also requires more extensive physiological degradation, possibly by the toxin alone as the active principle, but in instances also involving other assaults (e.g., hepatitis B virus). Since aflatoxin carcinogenesis involves complex effects, we have undertaken to define the range of influence of this common food contaminant upon a susceptible model, the broiler-type chick. Aflatoxicosis in two treated groups was indicated by jaundice, coagulopathy, dehydration of combs and shanks, retardation of body weight, and decrease in bursa weight. Blood clotting time, hemoglobin content, erythrocyte and packed-cell volume were affected. Hepatocytes were swollen and had undergone fatty degeneration. Bile duct hyperplasia was evident. Total serum protein, alkaline phosphatase, creatine, lactate dehydrogenase, serum glutamic oxalacetic transaminase and glutamyl transpeptidase were similarly abnormal in birds receiving the contaminated (0.5 and 2.5 micrograms/g aflatoxin B1) feed rations. The aflatoxin B1 and its metabolites were isolated by HPLC from chick serum, liver and muscle.     

Surface proteome mining for identification of potential vaccine candidates against Campylobacter jejuni: an in silico approach

Functional & Integrative Genomics - Campylobacter jejuni remains a major cause of human gastroenteritis with estimated annual incidence rate of 450 million infections worldwide. C. jejuni is a...