Characterizing cobalamin cycling by Antarctic marine microbes across multiple scales

Submitted in partial fulfillment of the requirements for the degree of Doctor of Philosophy in Biological Oceanography at the Massachusetts Institute of Technology and the Woods Hole Oceanographic Institution May 2020.Highly productive marine microbial communities in the coastal Southern Ocean sustain the broader Antarctic ecosystem and play a key role in Earth’s climate via the biological pump. Regional phytoplankton growth is primarily limited by iron and co-limited by cobalamin (vitamin B12), a trace cobalt-containing organometallic compound only synthesized by some bacteria and archaea. These micronutrients impact primary production and the microbial ecology of the two keystone phytoplankton types: diatoms and Phaeocystis antarctica. This thesis investigates microbe-driven cobalamin cycling in Antarctic seas across multiple spatiotemporal scales. I conducted laboratory culture experiments with complementary proteomics and transcriptomics to investigate the B12-ecophysiology of P. antarctica strain CCMP 1871 morphotypes under iron-B12 co-limitation. We observed colony formation under higher iron treatments, and a facultative use of B12-dependent (MetH) and B12-independent (MetE) methionine synthase isoforms in response to vitamin availability, demonstrating that this strain is not B12-auxotrophic. Through comparative ’omics, we identified a putative MetE protein in P. antarctica abundant under low B12, which is also found in other marine microbes. Across Antarctic seas, community-scale cobalt and B12 uptake rates were measured by 57Co radiotracer incubation experiments and integrated with hydrographic and phytoplankton pigment data. I observed significant correlations between uptake fluxes and environmental variables, providing evidence for predominantly diatom-driven uptake of these micronutrients in warmer, fresher surface waters with notable regional differences. To date, this work is the most comprehensive attempt to elucidate the processes governing the co-cycling of cobalt and B12 in any marine system. At the ecosystem-scale, I developed and tested a hypothesis of micronutrient-driven community dynamics through a trait-based model with cross-feeding interactions. The model demonstrates how the observed seasonal succession of springtime P. antarctica from solitary to colonial cells, bacterioplankton, and summertime diatoms may be explained by the microbial cycling of iron, dissolved organic carbon, and B12. Overall, this dissertation provides new information about the micronutrient-driven ecology of Antarctic marine microbes and adds to our understanding of the interconnections between organismal life cycle, trace metals, and trace organics in marine environments.My training as a scientist during my time in the MIT–WHOI Joint Program (2014-2020) and the work presented in this dissertation were financially supported by the Academic Programs Office (APO) at the Woods Hole Oceanographic Institution (WHOI) and various funding agencies. My first semester was supported by the WHOI Von Damm Fellowship (2014). Subsequent years and endeavors were supported by awards from the Gordon and Betty Moore Foundation to Professor Michael Follows (Award 3778, M.J.F.) and Simons Collaboration on Computational Biogeochemical Modeling of Marine Ecosystems (Award 549931, M.J.F.); National Science Foundation (NSF) grant to Dr. Stephanie Dutkiewicz (Grant number 1434007, S.D.), and NSF Office of Polar Program (OPP) grant to Dr. Makoto Saito (M.S.) for the CICLOPS research expedition (OPP-1643684, OPP-1643845, and OPP-1644073)

Accuracy of intraocular pressure measurements made over soft contact lenses using Tonopen XL and Pulsair 2000

The purpose of this investigation was to determine if intraocular pressure measurements made over soft contact lenses are affected by the refractive power of the contact lens and the type of tonometer used. Forty subjects ranging in age from 19 to 45 years, free from corneal abnormalities and glaucoma, participated in this study. Four minus power soft contact lenses, each having the same diameter, base curve, and central thickness, but differing in power (-l.SOD to -6.00D) were chosen. Intraocular pressures were measured over these lenses using two different tonometers, the Tonopen XL and Pulsair 2000. Results showed that intraocular pressure was not affected either by the power of the lens or the type of tonometer used. The differences in mean intraocular pressure with and without lenses were found to be statistically significant. This variability was however clinically acceptable, as the differences were within 1 mm of each other. In conclusion, intraocular pressure measurements taken over standard minus lenses with the Tonopen XL and Pulsair 2000 are reliable and acceptable

In Vivo and in Vitro Morphological Study of Epitenon Cell Populations in Chickens

The following study was conducted to classify cell populations found in the epitenon of the deep digital flexor tendons of chickens. Tendons heal very slowly and in many cases the prognosis of mechanical recovery following repair is very poor. Although various surgical and grafting procedures exist, satisfactory healing is dependent on achieving a balance between initial immobilization and passive controlled motion following repair. Well-defined post-operative exercise regimens are not readily available to deal with the diversity of tendon injuries and patient variability. What is needed is an additional treatment option to reduce post-operative healing time. One approach would be the incorporation of tendon cells at the site of injury to decrease the time of immobilization. Cell populations present in the epitenon are actively involved in healing, however, the various epitenon populations have not been well characterized. The following study was designed to classify epitenon cell populations of the chicken deep digital flexor tendon which has been previously used as a model for the study of tendon healing

A CONTROLLED CLINICAL STUDY ON THE EFFECT OF CERTAIN INDIGENOUS DRUGS IN SHAKHASHRITA KAMALA WITH SPECIAL REFERENCE TO VIRAL HEPATITIS-B

Hepatitis-B is an infective disease predominantly affecting liver. Along with AIDS, which has been a major concern since 90s. Many of the Ayurvedic herbal medicines have been tried and have been proved to be effective in treating Shakhashrita kamala. The objective of the study was to see the effect of tablet Nirocil and indigenous drugs Kashaya in Shakhashrita kamala (Hepatitis-B) and to compare both of them. A Total of 26 patients, after considering the inclusion and exclusion criteria, having signs and symptoms of Shakhashrita kamala were included in the study and after diagnosing Hepatitis-B by elevated liver function tests and HBsAg (Elisa). Patients were assessed and scores were given with regards to the subjective parameters like Peetata of netra, Peetata of Mootra, Peetata of Jihwa jala, Swethavarchas, Kandu and objective parameters like total bilirubin, and HBsAg. All the subjective parameters are recorded and assessed on initial day, during and after treatment. Objective parameters are assessed before and after treatment. Out of 26 patients, 10 patients got completely cured, 8 patients got improvement and 8 patients got slight improvement. Overall assessment of the study revealed that, after treatment of 26 patients, there were 8 patients having HBsAg positive result and 18 patients were having HBsAg negative result which was highly significant. Both the groups showed significant positive in subjective parameters. Thus study revealed that indigenous drugs Kashaya has significant role to play in the management of Shaksahashrita kamala. To conclude, the study emphasized that indigenous drugs Kashaya has significant role to play in the management of Shaksahashrita kamala

Using Authentic Medication Errors to Promote Pharmacy Student Critical Thinking and Active Learning

Objective: To promote first year (P1) pharmacy students’ awareness of medication error prevention and to support student learning in biomedical and pharmaceutical sciences. Innovation: A novel curricular activity was created and referred to as “Medication Errors and Sciences Applications (MESA)”. The MESA activity encouraged discussions of patient safety among students and faculty to link medication errors to biomedical and pharmaceutical sciences, which ultimately reinforced student learning in P1 curricular topics.   Critical Analysis: Three P1 cohorts implemented the MESA activity and approximately 75% of students from each cohort completed a reliable assessment instrument. Each P1 cohort had at least 14 student teams who generated professional reports analyzing authentic medication errors. The quantitative assessment results indicated that 70-85% of students believed that the MESA activity improved student learning in biomedical and pharmaceutical sciences. More than 95% of students agreed that the MESA activity introduced them to medication errors. Approximately 90% of students agreed that the MESA activity integrated the knowledge and skills they developed through the P1 curriculum, promoted active learning and critical thinking, and encouraged students to be self-directed learners. Furthermore, our data indicated that approximately 90% of students stated that the achievement of Bloom’s taxonomy's six learning objectives was promoted by completing the MESA activity. Next Steps: Pharmacy students’ awareness of medication errors is a critical component of pharmacy education, which pharmacy educators can integrate with biomedical and pharmaceutical sciences to enhance student learning in the P1 year. Treatment of Human Subjects: IRB exemption granted   Type: Note License: CC B

In situ carbon coated Li2MnSiO4/C composites as cathodes for enhanced performance li-ion batteries

An in-situ carbon coated Li2MnSiO4/C composite was synthesized by a nanocomposite gel precursor route using starch as the carbon source. Our approach enabled a uniform coating of amorphous carbon on Li 2MnSiO4 with an orthorhombic crystalline structure, which was confirmed by electron microscopy, X-ray diffraction and Raman studies. Conducting-atomic force microscopy (C-AFM) images also revealed the presence of high current interconnected domains in the composite, indicating the ability of the carbon coating to facilitate electron movement. Galvanostatic charge-discharge studies demonstrated outstanding initial charge and discharge capacities, respectively, of 330 and 195 mAh g-1 at 0.05 C-rate for the composite, and after 30 cycles a reversible capacity of 115 mAh g -1 was retained. The electrochemical performance of the neat silicate was dismal (10.6 mAh g-1 at 0.05 C-rate), which again reiterated the role of carbon in improving the conduction and Li-ion storage capacity of the silicate. An insignificant change in charge transfer resistance, with cycling, as inferred from impedance spectroscopy illustrated that charge transfer and transport processes remain facile with cycling, thus demonstrating Li 2MnSiO4/C to be promising cathode Li-ion batteries

Design and Development of a Mini-Orange Magnetic Spectrometer with Multichannel Facility for Conversion Electron Spectroscopy

Background: Conventional magnetic spectrometers used for conversion electron detection are very cumbersome, require strong magnetic fields and the spectra have to be scanned point by point and have very low transmission. A magnetic filter using permanent magnets and an Si(Li) detector would facilitate multichannel analysis with high transmission. The mini-orange is a new type of spectrometer for conversion electrons combining a solid state Si(Li) detector with a filter of permanent magnets around a central absorber of lead.Purpose: An indigenously developed magnetic spectrometer if optimized properly would be of great use in conversion electron spectroscopy for both online and offline experiments. Methods: A Mini-Orange magnetic spectrometer made of small permanent magnets has been designed and developed indigenously and optimized for its best performance condition. The transmission curves for different energy regions are plotted using the conversion electron spectra from the standard gamma transitions from 153Gd, 169Yb and 131Ba decays. The optimized spectrometer facilitates multichannel acquisition of conversion electron spectra for precision electron spectroscopy. The system also can be used in in-beam experiments with minor modifications of the vacuum chamber.Results: The optimized spectrometer was used for precision electron spectroscopy. Experimental transmission curves are then obtained by plotting Transmission (T) against the corresponding electron energy for low energy, medium energy and a broad energy range. Out of the several experiments done the optimum settings for f and g, that resulted in this curve, is identified at f = 7.5 cm and g = 4.5 cm. Conclusions: The optimized spectrometer facilitates multichannel acquisition of conversion electron spectra for precision electron spectroscopy. The system also can be used in in-beam experiments with minor modifications of the vacuum chamber

ASSOCIATION BETWEEN MICROALBUMINURIA AND OXIDATIVE STRESS IN DIABETIC NEPHROPATHY

Objectives: Diabetic Nephropathy (DN) is a leading cause of chronic kidney disease and end stage renal failure worldwide. This study aimed to evaluate the association between oxidants, antioxidants and microalbuminuria in Diabetic Nephropathy compared with Type II Diabetes Mellitus (DM). Methods: The study includes 60 Type II Diabetes Mellitus and 40 Diabetic Nephropathy Patients. Parameters performed HbA1c, urea, creatinine, total proteins, microalbuminuria, glutathione peroxidase and malondialdehyde(MDA). Results: The levels of HbA1c, urea, creatinine, microalbuminuria and malondialdehyde are significantly higher in DN compared with Type II DM. the levels of T.P and glutathione peroxidase are decreased in DN compared with Type II DM. Conclusion: Low levels of glutathione peroxidase and total proteins were observed in DN. HbA1c, urea, creatinine, microalbuminuria and malondialdehyde levels were elevated in DN compared with Type II DM.KEYWORDS: Diabetic Nephropathy; Glutathione peroxidase; Microalbuminuria; Malondialdehyde

ASSOCIATION BETWEEN MICROALBUMINURIA AND OXIDATIVE STRESS IN DIABETIC NEPHROPATHY

Objectives: Diabetic Nephropathy (DN) is a leading cause of chronic kidney disease and end stage renal failure worldwide. This study aimed to evaluate the association between oxidants, antioxidants and microalbuminuria in Diabetic Nephropathy compared with Type II Diabetes Mellitus (DM). Methods: The study includes 60 Type II Diabetes Mellitus and 40 Diabetic Nephropathy Patients. Parameters performed HbA1c, urea, creatinine, total proteins, microalbuminuria, glutathione peroxidase and malondialdehyde(MDA). Results: The levels of HbA1c, urea, creatinine, microalbuminuria and malondialdehyde are significantly higher in DN compared with Type II DM. the levels of T.P and glutathione peroxidase are decreased in DN compared with Type II DM. Conclusion: Low levels of glutathione peroxidase and total proteins were observed in DN. HbA1c, urea, creatinine, microalbuminuria and malondialdehyde levels were elevated in DN compared with Type II DM.KEYWORDS: Diabetic Nephropathy; Glutathione peroxidase; Microalbuminuria; Malondialdehyde

Zinc and copper levels in preeclampsia: a study from coastal South India

Background: Preeclampsia is one of the major causes of maternal and fetal morbidity and mortality. Though the etiology is obscure, studies indicate the role of oxidative stress and antioxidants may have a role in the prevention of preeclampsia. Micronutrients such as copper and zinc are involved in the antioxidant defense mechanism.Methods: The present study was undertaken in a medical college hospital in coastal South India to assess the serum levels of zinc and copper in women with preeclampsia and to compare them with normal pregnant women. The blood samples from 60 preeclamptic women and an equal number of controls were analyzed for zinc and copper levels. Outcome of pregnancy was analyzed and compared. Data were expressed as mean ± standard deviation. Comparison of levels of the elements between the two groups was performed by independent t test and Chi square test and P value of <0.05 was considered as statistically significant.Results: The serum zinc and copper levels were significantly lower in the preeclamptic group compared to the normotensives. Also preeclamptic women were older, their BMI was higher and birth weight of babies lower compared to normotensives.Conclusions: Increased knowledge about the importance of specific antioxidant micronutrients and their part in successful pregnancy outcome should be the focus for future health strategies. Low levels of maternal copper and zinc are related to preeclampsia and might have a causal role in this disease. Further investigation is needed to establish the role of these elements in this dangerous condition of pregnancy