Factors Influencing the Diversity of Iron Uptake Systems in Aquatic Microorganisms

Iron (Fe) is an essential micronutrient for many processes in all living cells. Dissolved Fe (dFe) concentrations in the ocean are of the order of a few nM, and Fe is often a factor limiting primary production. Bioavailability of Fe in aquatic environments is believed to be primarily controlled through chelation by Fe-binding ligands. Marine microbes have evolved different mechanisms to cope with the scarcity of bioavailable dFe. Gradients in dFe concentrations and diversity of the Fe-ligand pool from coastal to open ocean waters have presumably imposed selection pressures that should be reflected in the genomes of microbial communities inhabiting the pelagic realm. We applied a hidden Markov model (HMM)-based search for proteins related to cellular iron metabolism, and in particular those involved in Fe uptake mechanisms in 164 microbial genomes belonging to diverse taxa and occupying different aquatic niches. A multivariate statistical approach demonstrated that in phototrophic organisms, there is a clear influence of the ecological niche on the diversity of Fe uptake systems. Extending the analyses to the metagenome database from the Global Ocean Sampling expedition, we demonstrated that the Fe uptake and homeostasis mechanisms differed significantly across marine niches defined by temperatures and dFe concentrations, and that this difference was linked to the distribution of microbial taxa in these niches. Using the dN/dS ratios (which signify the rate of non-synonymous mutations) of the nucleotide sequences, we identified that genes encoding for TonB, Ferritin, Ferric reductase, IdiA, ZupT, and Fe(2+) transport proteins FeoA and FeoB were evolving at a faster rate (positive selection pressure) while genes encoding ferrisiderophore, heme and Vitamin B12 uptake systems, siderophore biosynthesis, and IsiA and IsiB were under purifying selection pressure (evolving slowly)

Fetomaternal outcome of women with thrombocytopenia in labour

Background: This study was conducted to study fetomaternal outcome in pregnancy with severity of thrombocytopenia. Methods: It was a prospective observational study of fetomaternal outcome of women with thrombocytopenia admitted in labour room of a tertiary health care center of south Gujarat for 1-year period (April 2021-March 2022) after official approval from ethical committee. 100 consecutive consenting women with thrombocytopenia admitted in labour room of New Civil Hospital Surat were enrolled in this study. Results: Mild thrombocytopenia was noted in 68% of the total cases, moderate thrombocytopenia in 27% and severe thrombocytopenia in 5% of cases. 59 subjects belong to age group of 20-25 years, 56 subjects were multipara, 70 subjects were registered antenatally, 68 subjects were delivered beyond 37 weeks of gestation. 48 subjects underwent LSCS and rest were delivered vaginally. 29 subjects had maternal complication. 95 subjects delivered alive baby of which 14 had NICU admission and 5 subjects had preterm still birth baby. Conclusions: Thrombocytopenia is the second most common haematological finding in pregnancy next to anaemia. Majority of cases generally present at gestational age beyond thirty-seven weeks and belong to category of mild thrombocytopenia. Efforts should be made on improving antenatal registration, screening of maternal thrombocytopenia, early diagnosis and treatment

Mother’s experience in alternate birth positions during second stage of labour

Background: The main objective of our research was to study mother’s experience in alternate birth positions during second stage of labour. Evidently, providing freedom to choose birthing positions positively impacts the women’s comfort level and intrapartum birthing experience. Methods: In the present study we counselled our antenatal and intranatal patients about the benefits and risks of alternate birthing positions. We enrolled 50 consecutive consenting parturients with prior vaginal delivery, who opted to adopt alternate birth position during second stage of labour. Maternal experience of birthing in alternate positions was compared to her experience in previous childbirth in dorsal position by using a standard pre-validated questionnaire using Likert scale with close ended and open-ended questions. Results: In our study, 49/50 (98%) mothers found alternate positions helpful, 46/50 (92%) mothers reported bearing down was easier, 47/50 (94%) mothers felt they would recommend alternate birth positions to others, for 49/50 (98%) parturients progression of labour was satisfactory, 48/50 (96%) had a good birthing experience, 44/50 (88%) felt duration of labour was less than what they had expected and 46/50 (92%) parturients reported that birthing experience in alternate birth position was more comfortable as compared to their previous delivery. Conclusions: Overall experience of delivering in alternate birth position was positive. Thus, it is clear that when women are informed and educated about their options, they are in a better position to make decisions from the available options and gain a sense of control over their healthcare with improved satisfaction and experience

ModEnzA: Accurate Identification of Metabolic Enzymes Using Function Specific Profile HMMs with Optimised Discrimination Threshold and Modified Emission Probabilities

Various enzyme identification protocols involving homology transfer by sequence-sequence or profile-sequence comparisons have been devised which utilise Swiss-Prot sequences associated with EC numbers as the training set. A profile HMM constructed for a particular EC number might select sequences which perform a different enzymatic function due to the presence of certain fold-specific residues which are conserved in enzymes sharing a common fold. We describe a protocol, ModEnzA (HMM-ModE Enzyme Annotation), which generates profile HMMs highly specific at a functional level as defined by the EC numbers by incorporating information from negative training sequences. We enrich the training dataset by mining sequences from the NCBI Non-Redundant database for increased sensitivity. We compare our method with other enzyme identification methods, both for assigning EC numbers to a genome as well as identifying protein sequences associated with an enzymatic activity. We report a sensitivity of 88% and specificity of 95% in identifying EC numbers and annotating enzymatic sequences from the E. coli genome which is higher than any other method. With the next-generation sequencing methods producing a huge amount of sequence data, the development and use of fully automated yet accurate protocols such as ModEnzA is warranted for rapid annotation of newly sequenced genomes and metagenomic sequences

Formulation and Optimization of Orodispersible Tablet of Loratadine Using Box Behnken Design

In present study Orodispersible tablets (ORDT) of Loratadine were prepared and optimized. Solid dispersion of Loratadine- β cyclodextrin complex were prepared and used in preparation of Orodispersible tablets. Various super-disintegrating agent like Cross carmellose sodium, Cross povidone and Kyron T-314 were employed for faster disintegrating effect. The 24 factorial and Box-Behnken design were utilized to optimize the tablet formulation. The Orodispersible tablet of Loratadine was optimized by Box Behnken Design, where concentrations Kyron T-314, CRP and Pearlitol SD200 were employed and its effect on Disintegration time (DT), Wetting time (WT) and % drug release at 20 min (Q20) was evaluated. Precompression parameters like angle of repose, bulk density, % compressibility, Hausner’s ratio was studies. The different batches of Orodispersable tablets were prepared and evaluated for disintegration time, friability, wetting time and drug release studies. Different batches prepared showed disintegration time in the range of 23 ± 2.52 to 59 ± 2.64, wetting time in between 27± 0.57 to 66.3 ± 3.4, drug release (Q 20) in between 86.1 ± 0.6 to 96.7 ± 0.4 in 20 min., friability less than 1 % and hardness 3.4 to 4.2 Kg/cm2. The optimized formula when compared with marketed product it showed faster disintegration time and rapid drug dissolution in phosphate buffer 6.8. The solid dispersion of Loratadine not only helped improve in solubility but may also help in taste masking. Keywords: Orodispersible tablets, Loratadine, β cyclodextrin Solid dispersio

Overview of fetomaternal outcome in twin gestation

Background: Twin pregnancy, involving the presence of two fetuses in the uterus, has intrigued humanity across history. Key challenges presented by twin pregnancies include prematurity, low birth weight (LBW), intrauterine growth restriction (IUGR), birth trauma, asphyxia, and congenital anomalies. Preterm delivery poses the most significant risk, contributing to elevated perinatal mortality, neonatal morbidity, and long-term health issues for twins. Methods: Retrospective study at Smt NHL Municipal Medical College analyzed 80 twin pregnancies from July 2022 to January 2024. Data included patient demographics, complications, and neonatal outcomes, informing findings through data analysis. Results: In this study, the majority were under 30 years old (56%) and primigravida (68%), with 48% having a BMI over 30. Common complications included preterm labor (70%), pregnancy-induced hypertension (27.5%), and gestational diabetes (20%). Most twin pregnancies were dichorionic diamniotic (80%). Caesarean section rate was 47.5%. Deliveries mostly occurred between 33-36 weeks gestation, with cephalic-cephalic presentation being most common (40%). Neonatal complications were primarily prematurity (50%), resulting in high NICU admissions (62%) and a neonatal death rate of 13.76%. Conclusions: Multiple pregnancies require early diagnosis and vigilant care to reduce maternal and perinatal risks. Access to skilled healthcare providers and advanced facilities is crucial. Antenatal care must be strengthened for timely referrals. Ultrasonography aids early complication detection. Further advancements and awareness are essential for improved outcomes

Aerobic Microbial Respiration In Oceanic Oxygen Minimum Zones

Oxygen minimum zones are major sites of fixed nitrogen loss in the ocean. Recent studies have highlighted the importance of anaerobic ammonium oxidation, anammox, in pelagic nitrogen removal. Sources of ammonium for the anammox reaction, however, remain controversial, as heterotrophic denitrification and alternative anaerobic pathways of organic matter remineralization cannot account for the ammonium requirements of reported anammox rates. Here, we explore the significance of microaerobic respiration as a source of ammonium during organic matter degradation in the oxygen-deficient waters off Namibia and Peru. Experiments with additions of double-labelled oxygen revealed high aerobic activity in the upper OMZs, likely controlled by surface organic matter export. Consistently observed oxygen consumption in samples retrieved throughout the lower OMZs hints at efficient exploitation of vertically and laterally advected, oxygenated waters in this zone by aerobic microorganisms. In accordance, metagenomic and metatranscriptomic analyses identified genes encoding for aerobic terminal oxidases and demonstrated their expression by diverse microbial communities, even in virtually anoxic waters. Our results suggest that microaerobic respiration is a major mode of organic matter remineralization and source of ammonium (~45-100%) in the upper oxygen minimum zones, and reconcile hitherto observed mismatches between ammonium producing and consuming processes therein

Giant Hydrogen Sulfide Plume in the Oxygen Minimum Zone off Peru Supports Chemolithoautotrophy

In Eastern Boundary Upwelling Systems nutrient-rich waters are transported to the ocean surface, fuelling high photoautotrophic primary production. Subsequent heterotrophic decomposition of the produced biomass increases the oxygen-depletion at intermediate water depths, which can result in the formation of oxygen minimum zones (OMZ). OMZs can sporadically accumulate hydrogen sulfide (H2S), which is toxic to most multicellular organisms and has been implicated in massive fish kills. During a cruise to the OMZ off Peru in January 2009 we found a sulfidic plume in continental shelf waters, covering an area >5500 km2, which contained ~2.2×104 tons of H2S. This was the first time that H2S was measured in the Peruvian OMZ and with ~440 km3 the largest plume ever reported for oceanic waters. We assessed the phylogenetic and functional diversity of the inhabiting microbial community by high-throughput sequencing of DNA and RNA, while its metabolic activity was determined with rate measurements of carbon fixation and nitrogen transformation processes. The waters were dominated by several distinct γ-, δ- and ε-proteobacterial taxa associated with either sulfur oxidation or sulfate reduction. Our results suggest that these chemolithoautotrophic bacteria utilized several oxidants (oxygen, nitrate, nitrite, nitric oxide and nitrous oxide) to detoxify the sulfidic waters well below the oxic surface. The chemolithoautotrophic activity at our sampling site led to high rates of dark carbon fixation. Assuming that these chemolithoautotrophic rates were maintained throughout the sulfidic waters, they could be representing as much as ~30% of the photoautotrophic carbon fixation. Postulated changes such as eutrophication and global warming, which lead to an expansion and intensification of OMZs, might also increase the frequency of sulfidic waters. We suggest that the chemolithoautotrophically fixed carbon may be involved in a negative feedback loop that could fuel further sulfate reduction and potentially stabilize the sulfidic OMZ water

Regulation of the phytoplankton heme b iron pool during the North Atlantic spring bloom

CITATION: Louropoulou, E., et al. 2019. Regulation of the phytoplankton heme b iron pool during the North Atlantic spring bloom. Frontiers in Microbiology, 10:1566, doi:10.3389/fmicb.2019.01566.The original publication is available at https://www.frontiersin.orgHeme b is an iron-containing co-factor in hemoproteins. Heme b concentrations are low (0.7 μm) from the North Atlantic Ocean (GEOVIDE cruise – GEOTRACES section GA01), which spanned several biogeochemical regimes. We examined the relationship between heme b abundance and the microbial community composition, and its utility for mapping iron limited phytoplankton. Heme b concentrations ranged from 0.16 to 5.1 pmol L⁻² (median = 2.0 pmol L⁻², n = 62) in the surface mixed layer (SML) along the cruise track, driven mainly by variability in biomass. However, in the Irminger Basin, the lowest heme b levels (SML: median = 0.53 pmol L⁻², n = 12) were observed, whilst the biomass was highest (particulate organic carbon, median = 14.2 μmol L⁻², n = 25; chlorophyll a: median = 2.0 nmol L⁻², n = 23) pointing to regulatory mechanisms of the heme b pool for growth conservation. Dissolved iron (DFe) was not depleted (SML: median = 0.38 nmol L⁻², n = 11) in the Irminger Basin, but large diatoms (Rhizosolenia sp.) dominated. Hence, heme b depletion and regulation is likely to occur during bloom progression when phytoplankton class-dependent absolute iron requirements exceed the available ambient concentration of DFe. Furthermore, high heme b concentrations found in the Iceland Basin and Labrador Sea (median = 3.4 pmol L⁻², n = 20), despite having similar DFe concentrations to the Irminger Basin, were attributed to an earlier growth phase of the extant phytoplankton populations. Thus, heme b provides a snapshot of the cellular activity in situ and could both be used as indicator of iron limitation and contribute to understanding phytoplankton adaptation mechanisms to changing iron supplies.https://www.frontiersin.org/articles/10.3389/fmicb.2019.01566/fullPublisher's versio