Natural DNA Uptake by Escherichia coli

Escherichia coli has homologues of the competence genes other species use for DNA uptake and processing, but natural competence and transformation have never been detected. Although we previously showed that these genes are induced by the competence regulator Sxy as in other gamma-proteobacteria, no conditions are known that naturally induce sxy expression. We have now tested whether the competence gene homologues encode a functional DNA uptake machinery and whether DNA uptake leads to recombination, by investigating the effects of plasmid-borne sxy expression on natural competence in a wide variety of E. coli strains. High- and low-level sxy expression alone did not induce transformation in any of the strains tested, despite varying the transforming DNA, its concentration, and the incubation conditions used. Direct measurements of uptake of radiolabelled DNA were below the limit of detection, however transformants were readily detected when recombination functions were provided by the lambda Red recombinase. This is the first demonstration that E. coli sxy expression can induce natural DNA uptake and that E. coli's competence genes do encode a functional uptake machinery. However, the amount of transformation cells undergo is limited both by low levels of DNA uptake and by inefficient DNA processing/recombination

Studies on the control of secondary thickening in excised roots of Lycopersicum esculentum Mill

1. In the first section of thin thesis the anatomy of excised tomato roots was compared and contrasted with that of cultured seedling roots. The remaining experimental work comprises a study of the effects of various growth substances on the initiation and growth of the cambium in excised tomato roots. Each substance was tested in two ways: (a) The roots were cultured immersed in a liquid medium supplemented with the compound(s). (b) The growth substances were fed via the cut end using a modified Raggio and Raggio technique (page 25). At the end of each experiment the roots were measured and the anatomy of the basal region of the roots was examined. The substances tested included auxins, cytokinins, a gibberellin, meso-inositol and various complex mixtures such as coconut milk, yeast extract and acid hydrolysed casein. The auxins, cytolcinins and meso-inositol were also tested in various combinations. 2. It has been shown that a well developed vascular cambium is initiated in two week old excised roots in the standard medium but that the activity of this cambium was not maintained. In contrast the cambium initiated in seedling roots was active up to six weeks. 3. It has been shown that IAA and NAA, at the concentrations tested, prevented the formation of a cambium and caused some reduction in the number of xylem cells in the stele. However when auxins were supplied via the cut end of the root no marked effect was observed. 4. Kinettn and 6-benaylaminopurine, added to the liquid medium, inhibited the formation of the cambium and greatly reduced the diameter of the stele and the number of xylem cells within the stele. When the cytokinins were supplied via the cut end, they increased the linear growth of the roots but had little effect on the anatomy aft the base. 5. The effects of gibberellic acid were similar to those of the auxins in that it prevented the formation of a cambium and reduced the number of xylem cells in the stele. 6. Although meso-inositol did not have a stimulatory effect on cambial activity after twooweeks it did markedly prolong its activity and roots grown in a meso-inositol supplemented medium for six weeks showed extensive secondary thickening. No effect on cambial activity was observed when the meso-inositol was fed via the cut end. In experiments with intact seedling roots meso-inositol similarly stimulated the activity of the vascular cambium. After one week's growth meso-inositol increased the growth of excised tomato roots by up to 60%. when added to the standard medium containing 2% sucrose. However, it was much-less effective in media containing 1% or 3% sucrose. After two weeks it was most effective in the medium containing 1% sucrose. Sorbitol, another cyc3litol, had little effect on the growth of tomato roots. 7. When the various combinations of IAA or NAA, cytokinins and meso-inositol were tested for effects on cambial growth, no positive interactions were observed. It was found that at the lower concentrations combinations of NAA, kinetin and meso-indsitol produced thick roots, but this reflected an effect on the thickness of the cortex rather than on the stele. 8. At the concentrations tested coconut milk, yeast extract and acid hydrolysed casein had no detectable effect on cambial activity when added to the liquid medium or when fed via the cut end of the root. 9. Excised roots cultured for six weeks in media supplemented with meso-inositol developed a considerable amount of secondary tissues which were derived from a vascular cambium. It is suggested that meso-inositol may be a factor limiting the cambial growth in excised tomato roots in standard medium. However meso-inositol did not produce roots with secondary tissues extensive as in comparable seedling roots and it was considered that other unidentified factors are also involved in cambium growth

ASSOCIATION OF SERUM HOMOCYSTEINE LEVELS WITH UNEXPLAINED STILL BIRTHS

Background This study examines the concept that elevated homocysteine levels are associated with sudden infant death syndrome. The study aimed to determine whether elevated serum homocysteine levels were related to an increased risk of iatrogenic stillbirths. Method In this retrospective case-control study, 100 women who had stillbirths for unknown reasons and 100 who had normal pregnancies served as cases and controls, respectively. The serum homocysteine levels were evaluated using enzyme assays, and other pertinent clinical and demographic information was also gathered. Result Significantly differing homocysteine levels were found between the case group (mean ± standard deviation: 12.5 ±2.1 units) and the control group (mean± standard deviation: 8.3± 1.5 units; p0.001). After adjusting for potential confounding factors  Conclusion The results suggest that elevated serum homocysteine levels may be a biomarker for the unknown risk of stillbirth in women. Further research is required into potential treatments and prevention strategies for hyperhomocysteinemia-related pregnancy complications. This study supports the theory that elevated homocysteine levels induce sudden infant death syndrome. Significant therapeutic implications result from these findings, as systematic homocysteine monitoring throughout pregnancy may help identify high-risk patients and implement appropriate therapies to reduce stillbirths. Recommendation There is a need for additional research to validate these findings and investigate methods to reduce maternal homocysteine levels such as maternal age, smoking status, and gestational age, logistic regression analysis revealed an important association between elevated serum homocysteine levels and unexplained stillbirths (odds ratio: 2.90, 95% confidence interval: 1.70-

Behavioural strategies of Wild bonnet macaques during natural foraging and provisioning(NIAS Report No. R1 - 99)

Artificial provisioning of free-living primate groups usually leads to a significant increase in competition for these newly available resources. Are individuals, however, capable of adopting suitable behavioural strategies to alleviate such tension? We studied the changing patterns of social interactions between adult females of a wild group of bonnet macaques (Macaca radiata radiata) in the Mudumalai Wildlife Sanctuary, Tamil Nadu, under two conditions of foraging. The group spent approximately 66 % of the observation time foraging on their natural diet; during the remaining period they gathered provisioned food from tourists visiting the sanctuary. Behavioural observations primarily consisted of about 139 hours of focal animal sampling on the 9 adult females in the group

Healthy blue man: congenital methemoglobinemia

Congenital methemoglobinemia, though often discussed in medical teachings is rarely encountered in clinical practice as the condition is asymptomatic. Here we present such a case and discuss in detail the clinical presentation of both congenital and acquired methemoglobinemia. We also outlined the management of the conditions. One should suspect methemoglobinemia when cyanosis is not being corrected by supplementing oxygen and and when the oxygen saturation is low by pulse oximetry and normal by arterial blood gas analysis. Treatment modalities for congenital methemoglobinemia is of cosmetic purpose, but timely intervention in acquired methemoglobinemia could be lifesaving. Methylene blue, Ascorbic acid and Riboflavin are drugs of choice

Prevalence of metallo-beta-lactamases (MBLS) producing Pseudomonas aeruginosa in hospitalized patients in rural tertiary care hospital in Uttar Pradesh, India

Background: Pseudomonas aeruginosa is a leading cause of nosocomial infections due to MBLs production with limited therapeutic options, higher rate of colonization is encountered in hospitalized patient streated with broad spectrum antibiotics. This study was conducted with an aim to know the prevalence of Carbapenem resistant MBLs producing strains of Pseudomonas aeruginosa in hospitalized patients.Methods: A total of 14700 samples were obtained from various wards during Jan 2016 to June 2017, were screened for P. aeruginosa by conventional culture and biochemical tests. All confirmed P. aeruginosa isolates were further subjected to Modified Kirby- Bauer disc diffusion test as per CLSI guidelines. All IPM resistant isolates were screened for MBL production by DDST, CDST, MHT and E-test MBL.Results: Atotal of 1423were identified as P. aeruginosa. The isolation rate of P. aeruginosa at our hospital was 9.7%. Among these, 130(9.1%) isolates were IPM resistant. A total of 111 (85.4%) were MBL positive by CDST and E-test, 92 (70.5%) by DDST and 80 (61.5%) by MHT. The prevalence of MBL producing P. aeruginosa was 111/1423(7.8%) while among IPM resistant P. aeruginosa, its prevalence was 111/130 (85.4%).Conclusions: The study documents presence of nosocomial MBL producing P. aeruginosa strains in our Institute. E-test and CDST were superior to DDST and MHT for detection of MBLs