Month: March 2020

TAG is a feedstock for the production of biofuels like biodiesel and bio–jet fuel, bioplastics, and other chemicals that are currently derived from fossil fuels. Moreover, because of its great growth potential and high photosynthetic efficiency, H. pluvialis is an alternative solution for removing CO2 from fossil-fired power plants. A two-stage cultivation strategy is often applied to mass culture of H. pluvialis. In the green stage, optimal light intensity and nutrient-replete media are provided to promote the growth of green vegetative cells; when the cell density reaches a maximal level, the culture is subjected to stress Tofacitinib conditions to induce astaxanthin biosynthesis and accumulation. At this red stage, many cells die off, while the surviving ones undergo profound biochemical and cellular changes, transforming the flagellates into red cysts. Although cell death is related to high light, high salinity, and other stressors, such as the application of acetate or Fe2+ to the cultures, the exact causes of cell death under stress remained largely unknown. The susceptibility of fast-growing H. pluvialis cells to adverse culture conditions leads to a substantial reduction in biomass productivity, a major obstacle that prevents expansion of the H. pluvialis industry. It has recently been observed that the H. pluvialis strain CCAP 34/12, which is dominated by flagellates at the exponential growth phase, was more susceptible to HL stress than another strain dominated by resting vegetative cells. These resting cells are also called palmella cells and are transformed from flagellates under favorable growing conditions. The death of flagellates under HL was attributed to the production of reactive oxygen species. Although a number of protective mechanisms contributing to the survival of SAG 34/1b under HL were identified, including down-regulation of linear photosynthetic electron transport and enhancement of the alternative plastid terminal oxidase pathway, it was unclear whether these mechanisms were developed during the cell transformation or resulted from different genetic makeups of the two Haematococcus strains. A recent comparative proteomic analysis of flagellates and resting cells from a single Haematococcus strain showed that a number of proteins involved in stress responses were induced in the resting cells but absent in the flagellates. The aim of this study was to determine the physiological and biochemical changes that occur during the transformation of motile flagellates into resting palmella cells and to dissect the key mechanisms by which the different forms of Haematococcus cells cope with HL. To gain more insight into the molecular–level changes in lipids that occur in response to HL, we developed a mass spectrometry–based lipidomics method for absolute quantification of glycerolipids. Our results suggest that introducing resting palmella from H. pluvialis.

This suggests that Laf4 has a stimulatory role on gene transcription, consistent with data obtained from the Af4-containing complex. This is also in accordance with a previous study showing that LAF4, like AF4 and AF5Q31, interacts with AF9/ENL protein, positive transcription elongation factor b and histone-H3 methyltransferase DOT1L. In further support of Laf4 function as a transcription regulator, overexpression of Laf4 in cortical cells led to an increase in BTAF1 RNA polymerase II, part of the pre-initiation transcription factor II D complex, and Max gene associated which binds to the transcription factor Max, a facultative component of the MLL1 complex. This suggests that Laf4 likely acts in collaboration with other transcription factors or chromatin remodellers to control gene transcription. Here, we demonstrate for the first time that Mdga2 is involved in cell migration during the process of cortical layering; indeed Mdga2 Fulvestrant over-expression was able to rescue the migration deficit resulting from Laf4 knockdown. It is noteworthy that while Mdga2 over-expression largely rescued the deficit, there was not a complete rescue. Interestingly, Mdga1, Mdga2 closest homologue, is required for neuronal migration. Thus, while Mdga2 plays a major role in Laf4-regulated migration, it may not be the only effector gene. Recent studies have shown that reduced levels of Mdga2 in open-book preparations from chicken embryos affect rostral growth of commissural axons. Moreover, Mdga2, like Mdga1, binds to neuroligin-2, and binding of Mdga1 to neuroligin2 inhibits neuroligin-2 synapse-promoting activity leading to reduction of synapse development and synaptic transmission in culture ; importantly, neuroligin-2 is expressed in the mouse brain from E18 to P25. Together, these studies suggest that, in addition to its role in cellular migration, Mdga2 may also affect axon growth and synapse formation in the developing cortex. Our current study has shed some important new light on the potential mechanisms underlying the developmental delay and cortical atrophy observed from a heterozygous LAF4 deletion in humans and repeat expansion silencing of the gene associated with ID. The cell migration data presented here may represent a greater degree of LAF4 knockdown than observed in these human conditions; but importantly, testing of additional shRNAs demonstrated that knockdown of Laf4 to levels that might be expected by haploinsufficiency results in alterations in expression of a transcriptional target of Laf4. Consequently, our results suggest that loss of LAF4 expression may have resulted in defective cell migration during early cortical development. Mutations in genes involved in neuronal cell migration have previously been associated with developmental delay and ID in humans. For example, doublecortin is associated with band heterotopia, a condition with severe intellectual disability and epilepsy, and which has been shown to be a consequence of radial migration deficits during neocortex development. Doublecortin is also associated with lissencephaly, a disease presenting severe ID, seizures and brain with reduced gyration. Similarly, mutations in LIS1, a gene involved in radial cortical neuronal migration, have also been associated with lissencephaly.

Considering the two limitations described, we are planning further experiments with a choline-folic acid-deficient/low-methionine diet in the next study, which would attenuate the possible effect of the weight loss. Third, although alterations of several mRNA expressions including Dnmt strongly suggest that rearrangement of DNA methylation occurred in the brains of FMCD mice, our study does not include direct evidence. Further study showing the actual occurrence of the epigenetic alteration would be desirable. However, it should be noted that a previous study revealed that long-term reduction of dietary methyl donors induced the rearrangement of DNA methylation in the rat brain. In summary, we examined the effects of FMCD exposure during the developmental period on emotional behaviors and hippocampal gene expressions in juvenile and adult mice. Feeding mice an FMCD diet during the developmental period induced severe impairment of memory acquisition and a decrease in anxiety-like behavior. Feeding the same mice a normal diet after the FMCD treatment partially reversed the behavioral alteration, but the adult mice still had impairment in fear-memory consolidation or retrieval while anxiety-like behavior was elevated. Gene expressions of Dnmt3a and 3b in the hippocampus were decreased by the FMCD exposure, which strongly suggests the occurrence of DNA methylation rearrangement in the FMCD mice group. Changes in gene expressions of Grin2b and Gabra2/3 might have been involved in the mechanism behind the behavioral alterations. Our study suggests that altering the one-carbon metabolic pathway in the developmental brain could affect emotional behavior and memory formation. Excessive vitamin A intake resulted in congenital malformations during embryonic development and also had a toxic effect on the liver in broilers. Excessive supplementation with vitamin A might increase the risk of bone fractures by depleting vitamin D, and it has a detrimental effect on the immune function of birds. However, Veltmann et al. reported that birds could tolerate as much as 30 times the recommended level of vitamin A without showing compromised performance or damage to skeletal development, as measured by bone ash. Although many studies have examined the effects of vitamin A on immunity, growth, and development in EX 527 side effects broilers and layers, few studies have explored the effects of high levels of dietary vitamin A supplementation on broiler breeder hens. Veltmann and Jensen compared vitamin A toxicity in Single Comb White Leghorn chicks, broilers, and turkey poults and found that a differential response to vitamin A toxicosis existed within breeds and across species. The effect of high levels of dietary vitamin A supplementation on broiler breeder hens is unknown. It is known that all forms of vitamin E are absorbed in the intestine, but there are several unknowns concerning metabolism. a-tocopherol is absorbed by a passive diffusion process from the small intestine to the enterocyte. Dietary retinoic acid reduced the intestinal absorption of a-tocopherol and promoted its oxidation or increased vitamin E turnover. Research on vitamin E absorption found that excess a-tocopherol did not reduce the absorption of c-tocopherol.

Up-regulation of a-enolase expression has been extensively reported for several types of cancer, including hepatocellular carcinoma, thyroid oncocytoma, lung and breast cancers among many others, and ENO1 gene expression is increased in 18 of 24 cancers classes analyzed. In some cases, overexpression of a-enolase positively correlated with tumor progression and clinical outcome. Additionally, altered levels of a-enolase were also found in Alzheimer’s disease, rheumatoid arthritis and systemic sclerosis. Alterations in a-enolase expression were also reported for flaviviruses’ infections. a-enolase is one of the up-regulated proteins in the midguts of Aedes aegypti mosquitoes and in the Aedes albopictus C6/36 cell line infected with different serotypes of DENV. Interestingly, a-enolase interacts with different viral proteins during the infection, including the capsid protein from DENV, envelope protein from WNV, NS3 protein from Kunjin virus and NS5 protein from Tick-borne encephalitis virus and from Alkhurma virus, although the biological relevance of these interactions remains unclear. Previously considered a cytoplasmic protein, a-enolase has also been identified in nucleus, plasma membrane, endosome, Golgi complex, peroxisome and in XL-184 extracellular exosome vesicles. It is noteworthy that enolase lacks signal sequences for any specific subcellular localization, and the molecular mechanisms involved in its membrane association as well as in its secretion are unknown. The subcellular localization of a-enolase is also modulated in different pathological states. For instance, LPS induces the translocation of a-enolase from cytoplasm to plasma membrane in monocytes. Also, an increase in a-enolase secretion has been observed in response to HIV-1 infection in macrophages and to DENV infection in hepatic cells, as reported here and in our previous study. Alterations in the secretion of a-enolase by liver cells could be involved not only in local effects, as cellular infiltration and hemorrhage reported in liver from patients who died from dengue, but also influence in systemic effects of dengue pathology such as plasma leakage and coagulopathies. Indeed, our preliminary results obtained with plasma samples from DENV-infected patients suggest an association between plasma levels of a-enolase and disease severity. These results point to a potential physiological role of a-enolase in dengue diseases. Another hypothesis for the role of a-enolase in dengue pathogenesis is that the increased amounts of extracellular, and possibly the membrane-associated, a-enolase would elicit humoral and cellular responses due to the production of autoantibodies and activation of T cells. Detection of anti-enolase antibodies has been reported for several inflammatory and autoimmune diseases, such as pancreatic cancer, lupus erythematosus, rheumatoid arthritis and inflammatory bowel disease. In addition, the presence of autoantibodies specifically to phosphorylated and citrullinated isoforms of a-enolase has been detected in serum from patients with pancreatic cancer and rheumatoid arthritis, respectively. Anti-enolase antibodies induced apoptosis in endothelial cells and production of inflammatory mediators.

Moreover, Streptomyces has become an important production host for heterologous expression of recombinant proteins due to its excellent secretion capacity, which makes the downstream processing much simpler. Therefore, understanding of the mechanism of its protein export systems is extremely important for the economical application of Streptomyces. Protein transport across the bacterial membrane is mediated by different translocation systems, of which the general protein secretion system plays a prominent role in protein export and membrane insertion. The Sec translocation machinery is a protein complex comprised of SecYEG, the ATPase SecA, and the accessory factor SecDF. The roles of the Sec pathway components have been extensively studied, but the function of the SecDF complex in protein secretion is still poorly understood. The SecDF complex has been shown to be involved in the cycling of SecA and the release of the translocated protein from the translocation channel. Recently, the SecDF complex was proposed to be a membrane integrated chaperone that uses proton motive force to complete protein translocation through the SecYEG channel via the control of SecA cycling. Chronic heart failure, which affects over 5 million people in the US, is associated with increased incidence of sudden death primary from ventricular tachycardia degenerating to ventricular fibrillation. A FTY720 morning surge in sudden deaths and ventricular arrhythmias have been demonstrated in patients with CHF. The onset of other cardiovascular events such as heart attack, stroke and chest pain is also increased in the morning. The underlying mechanisms are poorly understood, in part due to a lack of characterization of heart rate dynamics, autonomic oscillation and nonlinear dynamics in time-of-day-dependent adverse cardiac events in large animal CHF models. Moreover most studies to date have been done primarily in HF patients and have been limited and influenced by concurrent medication use. Time-of-day-dependent variations in heart rate dynamics, autonomic nervous system and nonlinear dynamics are associated with the morning surge in cardiovascular events. Heart rate variability can assess the regulation of arrhythmogenic substrate in CHF of the failing heart. Traditional linear HRV is analyzed in the time and frequency domain, and markers include SDNN, CV, and rMSSD, spectral power in different frequency range, etc. HRV has been shown to have important prognostic implications. Heart rate fluctuations have been recognized as complex dynamical behaviors originating from nonlinear processes. Despite knowledge of HRV parameters in patients with CHF which are associated with a morning surge in ventricular arrhythmias, the underlying mechanisms contributing to these important observations have remained elusive. We have recently developed a novel arrhythmogenic large animal model of CHF in the canine heart that exhibits decreased LV function and spontaneous ventricular arrhythmia that are initiated and maintained by a focal nonreentrant mechanism. The purpose of the present study was to assess whether there is a morning surge in premature ventricular complexes and VT in our new irreversible arrhythmogenic canine CHF model.