Investigating Photosynthetic Stability: Relation Between Thylakoid Lipid Content and the Stability of the Cytochrome b6f Complex

The cytochrome b6f complex is an enzyme found in plants, cyanobacteria, and green algae that catalyzes the transport of electrons in the rate-limiting step of oxygenic photosynthesis. This dimeric complex has an extensive lipid architecture that is primarily composed of five distinct lipid classes: monogalactosyl diacylglycerol (MGDG), digalactosyl diacylglycerol (DGDG), phosphatidyl glycerol (PG), monoglucosyl diacylglycerol (GlcDG), and sulfoquinovosyl diacylglycerol (SQDG). While these lipid classes have been identified, their precise role in the function of the cytochrome complex are only beginning to be understood. Mechanisms describing the relation between thylakoid lipid content on the stability of the b6f complex are not known. This study validates the importance of the lipids on cytochrome b6f dimer formation and stability by showing that SQDG and the synthetic lipids 1,2-dioleoylphosphatidylglycerol and 2-dioleoyl-sn-glycero-3-phosphocholine reduce the temperature dependent rate of monomerization (denaturation) of the native dimer. A novel method of growing the cyanobacterium Synechococcus PCC 7002 anaerobically to test the relation between thylakoid lipid content and growth temperature was developed. This method of growing Synechococcus greatly reduces the relative SQDG content and increases the relative PG content in thylakoid membranes. The analysis of MGDG, DGDG, PG, GlcDG, and SQDG content in Synechococcus cultures grown at 30℃ and 33℃ revealed that the MGDG content depends inversely on the growth temperature

An Investigation of a Cluster S Mycobacteriophage Genome, Corazon, Genes 4-16: Location and Function

Mycobacteriophages are a type of virus particle that specifically attack mycobacteria. This attribute can be exploited to fight antibiotic resistance mycobacteria. As of February 2019, only 14 Cluster S types (a specific group of mycobacteriophage) have been completely sequenced and published in the Actinobacteriophage Database. The purpose of this investigation is to establish the presence, location, and function of genes within the genome of a novel bacteriophage, Corazon and add to this database. Corazon, isolated from a soil sample collected in Lafayette, Indiana, is a member of Cluster S and belongs to the Siphoviridae morphotype. It has 109 genes and a 64kbp genome size. The genome was analyzed with the program DNA Master and a variety of sources such as NCBI BLAST, HHPred, and Phamerator to determine the location and function of genes within the auto-annotated range of genes 4-16. Within the investigated range, only one gene was assigned a function (MazG-like nucleotide pyrophosphohydrolase, which interacts with an essential GTPase in bacteria). The other 13 genes were annotated as genes with no known function. The investigation of significant gaps in the genome resulted in an additional gene (14.5) being added. Contributing to the global understanding of bacteriophages is of interest since the phage-bacteria model has expanded scientists’ capabilities of studying evolution and exploring novel medical applications. Publishing these annotations will allow generations of researchers to compare their results to this member of Cluster S and potentially identify a new candidate for phage-mediated transduction, phage therapy, or other application

Engineering Pseudomonas putida KT2440 for chain length tailored free fatty acid and oleochemical production.

Despite advances in understanding the metabolism of Pseudomonas putida KT2440, a promising bacterial host for producing valuable chemicals from plant-derived feedstocks, a strain capable of producing free fatty acid-derived chemicals has not been developed. Guided by functional genomics, we engineered P. putida to produce medium- and long-chain free fatty acids (FFAs) to titers of up to 670 mg/L. Additionally, by taking advantage of the varying substrate preferences of paralogous native fatty acyl-CoA ligases, we employed a strategy to control FFA chain length that resulted in a P. putida strain specialized in producing medium-chain FFAs. Finally, we demonstrate the production of oleochemicals in these strains by synthesizing medium-chain fatty acid methyl esters, compounds useful as biodiesel blending agents, in various media including sorghum hydrolysate at titers greater than 300 mg/L. This work paves the road to produce high-value oleochemicals and biofuels from cheap feedstocks, such as plant biomass, using this host

Pain intensity and severe pain in young immigrant patients with long-standing back pain

The aim of this study was to explore if self-rated pain intensity and severe pain differed significantly between immigrants from different regions, and if other socio-economic, or clinical, characteristics could predict severe pain. A total of 129 men and 217 women at a primary health centre in Stockholm, Sweden, 27–45 years, on long-term sick leave, were recruited in consecutive order and grouped into a Turkish (n = 122), Southern European (n = 52), Middle East (n = 69) and one Mixed (n = 173) group of immigrants. All were employed in service jobs. Somatic status, depression and level of psychosocial stressors, including pain anxiety, were established by standardized procedures. All reported long-standing disabling back pain. Patients rated intensity of pain “right now” on a 0–100 mm visual analogue scale (VAS) as a last part of the consultation with two doctors. Severe pain was defined as VAS 75–100. Median values (md) with inter-quartile ranges (IQR) were calculated for interval and ordinal data. Non-parametric statistics were used to calculate significant differences between groups. Crude and age-standardized odds ratios (OR) with 95% confidence intervals (95% CI) as rating severe pain were calculated by binary and forward conditional logistic regression. Men and women were analyzed separately. Women had more tender points, (P < 0.001), and reported pain anxiety more often (P < 0.01). Frequency of depression did not differ between the immigrant groups. The VAS-values varied, but not significantly, between the immigrant groups of men and women. Men had lower VAS values than women (md 50, IQR 36–69 vs. md 72, IQR 51–85), (P < 0.001). Women had a three-fold risk to rate severe pain (OR 2.9, 95% CI 1.8–4.7). By sex, no immigrant group had significantly elevated OR to rate severe pain. Being 40–45 year old doubled the OR as rating severe pain. Men with depression, or little education, had high risks as rating severe pain (age-standardized ORs 4.1; 95% CI 1.7–10.0 and 2.7; 95% CI 1.1–6.8, respectively), and so had depressed women (age-standardized OR 1.9; 95% CI 1.1–3.4). Women with pain anxiety had a doubled, not statistically significant, elevated risk (age-standardized OR 2.0, 95% CI 0.95–4.3). The groups did not differ significantly in pain intensity or severe pain. Severe pain was predicted by depressed mood and probably linked to gender, age and sick roles