Distribution and molecular characterisation of Lactobacilli in the oral cavity of children

Background

Dental caries is a chronic and multifactorial disease mainly caused by microorganisms that are accumulated on soft and hard tissues of oral cavity. Lactobacillus is one of that kind, produces acid after metabolic breakdown of dietary sugar and reduces the pH of oral environment, resulting in teeth demineralisation or dental caries.

Aim

The present study focuses on the distribution and characterisation of lactobacilli in the oral cavity of children which are associated with dental caries formation.

Methods

Total 116 swab samples were collected from different age groups of children by swabbing the caries surface of teeth. Physiological, morphological and biochemical characteristics of Lactobacillus were analysed. Whole cell protein profiling using SDS-PAGE was also performed for their characterisation. Molecular characterisation of selected isolates was done using 16S-rRNA sequencing for identification.

Results

Total 269 isolates were successfully isolated and identified by physiological and biochemical tests according to Bergey's Manual Systematic Bacteriology, which belongs to the seven species of Lactobacillus i.e., L. acidophilus, L. casei, L. delbrueckii, L. helveticus, L. plantarum, L. rhamnosus, L. salivarius. All the isolates were further differentiated by whole cell proteins profiling and species level identification was done by 16S-rRNA gene sequencing method.

Conclusions

The present study, suggested that the occurrence of the species of Lactobacillus changes with the age of the individual, but L. rhamnosus (20.54%) and L. acidophilus (18.21%) were abundantly found in age group of 3-12 yr which could be the possible causative agent of dental caries formation in the children of Central India.

Metabolic and histopathological alterations of Jatropha mosaic begomovirus-infected Jatropha curcas L. by HR-MAS NMR spectroscopy and magnetic resonance imaging

Alterations in the anatomical structures, sap translocation and metabolic profiles in Jatropha curcas L. (Euphorbiaceae), infected with Jatropha mosaic virus (JMV) have been investigated using MRI and HR-MAS NMR spectroscopy. The contrast of MRI images distinguishes abnormalities in anatomical structures of infected and healthy stem. The HR-MAS NMR spectroscopic analysis indicated that viral infection significantly affected the plant metabolism. Higher accumulation of TCA cycle intermediates, such as citrate and malate, in JMV-infected plants suggested a higher rate of respiration. The respiration rate was more than twofold as compared to healthy ones. The viral stress also significantly increases the concentrations of alanine, arginine, glutamine, valine, GABA and choline as compared to healthy ones. Microscopic examination revealed severe hyperplasia caused by JMV with a considerable reduction in the size of stem cells. Lower concentration of glucose and sucrose in viral-infected stem tissues indicates decreased translocation of photosynthates from leaves to stem due to hyperplasia caused by JMV. The MR images distinguished stele, cortical and pith regions of JMV-infected and healthy stems. Contrast of T(1)- and T(2)-weighted images showed significant differences in the spatial distribution of water, lipids and macromolecules in virus-infected and healthy stem tissues. The results demonstrated the value of MRI and HR-MAS NMR spectroscopy in studying viral infection and metabolic shift in plants. The present methodology may help in better understanding the metabolic alterations during biotic stress in other plant species of agricultural and commercial importance.

First Report of Cucumber mosaic virus on Jatropha curcas in India

Jatropha curcas L. is a major commercial biodiesel fuel crop grown on 98 million acres (39.66 million ha) in India. Severe mosaic disease accompanied by yellow spots was noticed on 15% of J. curcas growing in the experimental plots of NBRI, Lucknow, India, during October of 2006. Inoculations with sap from symptomatic plants resulted in systemic mosaic on three of seven J. curcas seedlings. Gel diffusion tests were performed with antiserum to Cucumber mosaic virus (CMV), Tobacco ringspot virus, and Chrysanthemum virus B (PVAS-242a, PVAS-157, and PVAS-349, respectively; ATCC, Manassas, VA). Leaf sap of infected plants reacted only with PVAS-242a, indicating the presence of CMV. Reverse transcription (RT)-PCR assays with CMV coat protein gene specific primers (Genbank Accession Nos. AM180922 and AM180923) and total nucleic acid extracted from symptomatic J. curcas leaf tissue yielded the expected ~650-bp amplicon, which was cloned and sequenced (GenBank Accession No. EF153739). BLAST analysis indicated 98 to 99% nucleotide identity with CMV isolates (GenBank Accession Nos. DQ914877, DQ640743, AF350450, AF281864, X89652, AF198622, DQ152254, DQ141675, and DQ028777). Phylogenetic analysis showed that the J. curcas isolate was more closely related to Indian isolates of CMV belonging to subgroup Ib. Literature surveys revealed records of Jatropha mosaic virus on J. gossypiifolia in Puerto Rico (1) and on J. curcas in India (2). To our knowledge, this is the first report of CMV on J. curcas. References: (1) J. K. Brown et al. Arch. Virol. 146:1581, 2001. (2) D. S. A. Narayana et al. Curr. Sci. 91:584, 2006.

Natural Occurrence of Cucumber mosaic virus on Rauvolfia serpentina, A New Record

Rauvolfia serpentina, family Apocynaceae, is widely cultivated in India and adjoining countries for the production of roots used in several herbal formulations (1). Severe mosaic and stunting of the whole plant was observed on R. serpentina growing in experimental plots of NBRI, Lucknow, in 2006. The causal pathogen was transmitted by sap inoculation on Nicotiana tabacum cv. White Burley, N. rustica, and N. glutinosa, which produced necrotic local lesions and systemic mosaic. The virus reacted positively with antiserum of Cucumber mosaic virus (CMV; PVAS 242a, ATCC, Manassas, VA) in gel double diffusion tests, indicating the presence of CMV. Total RNA was isolated from infected and healthy leaf tissues of R. serpentina, and reverse transcription (RT)-PCR was performed using CMV specific primers AM180922/AM180923. RT-PCR resulted in an expected size (~650 bp) amplicon in infected but not healthy samples. The amplicon was cloned, sequenced, and the data was submitted to GenBank (Accession No. DQ914877). BLAST search analysis of the virus isolate showed highest (99%) sequence identity with CMV isolates (GenBank Accession Nos. DQ640743, AF350450, X89652, and AF281864). The virus isolate showed a close phylogenetic relationship with Indian isolates of CMV belonging to subgroup IB. A literature survey revealed that there is no report of occurrence of any virus on R. serpentina except some fungal infections (2). To our knowledge, this is the first record of natural occurrence of CMV on R. serpentina. References: (1) Anonymous. Wealth of India 8:376, 1969. (2) R. S. Shukla et al. EPPO Bull. 36:11, 2006.

A Yellow Mosaic Disease of Soybean in Northern India is Caused by Cotton leaf curl Kokhran virus

Soybean, Glycine max (L.) Merr., is a protein- and oil-rich crop cultivated in India and abroad. A yellow mosaic disease was observed on soybean with 80 to 90% disease incidence during August 2005 at fields of the National Botanical Research Institute, Lucknow, in northern India. Soybean plants were found to be infested with whiteflies (Bemisia tabaci) suggesting begomovirus etiology. The disease agent was transmitted experimentally by whiteflies, and symptoms developed after 23 days. Total DNA was isolated from 51 leaf samples collected from 42 symptomatic and 9 asymptomatic plants. Polymerase chain reaction was performed using begomovirus coat protein-specific primers 5'-ATGGCGAA GCGACCAG-3' and 5'-TTAATTTGTGACCGAATCAT-3' (AM180920/ AM180921). An amplicon of the expected size (~800 bp) was obtained in all 42 symptomatic leaves but not from any of the nine asymptomatic leaf samples. The amplicon was cloned, and the identical sequence of three clones was submitted to GenBank (Accession No. DQ343283). BLAST search of nucleotide sequences revealed 95% identity with Cotton leaf curl Kokhran virus (CLCKV) (GenBank Accession Nos. AJ002449, AJ002448, AJ496286, and AY456683) and 57% identity with Mungbean yellow mosaic India virus (MYMIV-Sb, GenBank Accession No. AY049772). Results indicated that the virus associated with yellow mosaic disease of soybean is an isolate of CLCKV rather than MYMIV-Sb (1) reported earlier on soybean from northern India. To our knowledge, this is the first report of soybean as a new host of Cotton leaf curl Kokhran virus. Reference: (1) K. S. Usharani et al. Curr. Sci. 86:845, 2004.