Conditions Of Nutritional Deficiency Research Articles

Starch Branching Enzyme 1 Is Important for Amylopectin Synthesis and Cyst Reactivation in Toxoplasma gondii.

ABSTRACTToxoplasma gondii (T. gondii) bradyzoites facilitate chronic infections that evade host immune response. Furthermore, reactivation in immunocompromised individuals causes severe toxoplasmosis. The presence of abundant granules containing the branched starch amylopectin is major characteristic of bradyzoites that is nearly absent from tachyzoites that drive acute disease. T. gondii genome encodes to potential Starch branching enzyme 1 (SBE1) that creates branching during amylopectin biosynthesis. However, the physiological function of the amylopectin in T. gondii remains unclear. In this study, we generated a SBE1 knockout parasites and revealed that deletion of SBE1 caused amylopectin synthesis defects while having no significant impact on the growth of tachyzoites under normal culture conditions in vitro as well as virulence and brain cyst formation. Nevertheless, SBE1 knockout decreased the influx of exogenous glucose and reduced tachyzoites proliferation in nutrition-deficient conditions. Deletion of SBE1 together with the α-amylase (α-AMY), responsible for starch digestion, abolished amylopectin production and attenuated virulence while restoring brain cyst formation. In addition, cysts with defective amylopectin metabolism showed abnormal morphology and were avirulent to mice. In conclusion, SBE1 is essential for the synthesis of amylopectin, which serves as energy storage during the development and reactivation of bradyzoites.IMPORTANCE Toxoplasmosis has become a global, serious public health problem due to the extensiveness of the host. There are great differences in the energy metabolism in the different stages of infection. The most typical difference is the abundant accumulation of amylopectin granules in bradyzoites, which is almost absent in tachyzoites. Until now, the physiological functions of amylopectin have not been clearly elucidated. We focused on starch branching enzyme 1 (SBE1) in the synthesis pathway to reveal the exact physiological significance of amylopectin. Our study clarified the role of SBE1 in the synthesis pathway and amylopectin in tachyzoites and bradyzoites, and demonstrated that amylopectin, as an important carbon source, was critical to parasites growth under an unfavorable environment and the reactivation of bradyzoites to tachyzoites. The findings obtained from our study provides a new avenue for the development of Toxoplasma vaccines and anti-chronic toxoplasmosis drugs.

Connecting nutritional deprivation and pubertal inhibition via GRK2-mediated repression of kisspeptin actions in GnRH neurons

BackgroundPerturbations in the timing of puberty, with potential adverse consequences in later health, are increasingly common. The underlying neurohormonal mechanisms are unfolded, but nutritional alterations are key contributors. Efforts to unveil the basis of normal puberty and its metabolic control have focused on mechanisms controlling expression of Kiss1, the gene encoding the puberty-activating neuropeptide, kisspeptin. However, other regulatory phenomena remain ill-defined. Here, we address the putative role of the G protein-coupled-receptor kinase-2, GRK2, in GnRH neurons, as modulator of pubertal timing via repression of the actions of kisspeptin, in normal maturation and conditions of nutritional deficiency. MethodsHypothalamic RNA and protein expression analyses were conducted in maturing female rats. Pharmacological studies involved central administration of GRK2 inhibitor, βARK1-I, and assessment of gonadotropin responses to kisspeptin or phenotypic and hormonal markers of puberty, under normal nutrition or early subnutrition in female rats. In addition, a mouse line with selective ablation of GRK2 in GnRH neurons, aka G-GRKO, was generated, in which hormonal responses to kisspeptin and puberty onset were monitored, in normal conditions and after nutritional deprivation. ResultsHypothalamic GRK2 expression increased along postnatal maturation in female rats, especially in the preoptic area, where most GnRH neurons reside, but decreased during the juvenile-to-pubertal transition. Blockade of GRK2 activity enhanced Ca+2 responses to kisspeptin in vitro, while central inhibition of GRK2 in vivo augmented gonadotropin responses to kisspeptin and advanced puberty onset. Postnatal undernutrition increased hypothalamic GRK2 expression and delayed puberty onset, the latter being partially reversed by central GRK2 inhibition. Conditional ablation of GRK2 in GnRH neurons enhanced gonadotropin responses to kisspeptin, accelerated puberty onset, and increased LH pulse frequency, while partially prevented the negative impact of subnutrition on pubertal timing and LH pulsatility in mice. ConclusionsOur data disclose a novel pathway whereby GRK2 negatively regulates kisspeptin actions in GnRH neurons, as major regulatory mechanism for tuning pubertal timing in nutritionally-compromised conditions.

Effect of low dose of berberine on the radioresistance of cervical cancer cells via a PI3K/HIF-1 pathway under nutrient-deprived conditions

Purpose: Radiotherapy (RT) is one of the major treatments of cervical cancer. Although the prognosis of clinical cervical cancer becomes better in recent years, some patients still suffer from the recurrence and metastasis. Insufficiency of glucose and oxygen supply could increase the radioresistance of cervical cancer cells through regulating hypoxia-inducible factor 1 (HIF-1) in tumor microenvironment and glucose metabolism. And, berberine can regulate HIF-1. However, how berberine regulates tumor microenvironment and radioresistance through HIF-1 remains to be elucidated.Materials and methods: The human HeLa cervical cancer cells were treated with berberine and radiation under the high and low concentrations of glucose and oxygen, respectively. The survival of cells was tested by CCK-8 assay and colony formation assay. We investigated the PI3K- and IDH3α-related pathway molecules that may regulate HIF-1α by qPCR and western blot. Differentially expressed genes (DEGs) were identified by integrating five related cohort profile datasets. Protein–protein interaction (PPI) network analyses of DEGs related to HIF-1α were conducted by using the STRING database and Cytoscape software.Results: Berberine dramatically damaged HeLa cells under hypoxic and low-glucose conditions compared with the normoxic and high-glucose conditions. The clonogenic assay indicated that the application of berberine decreased the number of colony counts compared to the negative control. Low doses of berberine might decrease the level of phospho-PI3K and HIF-1α under the nutrient-deprived conditions. Moreover, we found that most of the differentially expressed genes which were related to CDKN1B were the downstream molecules regulated by HIF-1α.Conclusion: The results indicated that berberine could dramatically overcome the low-glucose and hypoxia-induced radioresistance. And the regulation berberine on nutrition-deficient conditions might involve in PI3K/HIF-1 pathway. Thus, the interference of glucose metabolism by berberine might be an attractive method to eliminate radioresistant cells and improve radiotherapy efficacy.

Effects of Nutritional Deficiency of Boron on the Bones of the Appendicular Skeleton of Mice.

Scientific evidence has shown the nutritional importance of boron (B) in the remodeling and repair of cancellous bone tissue. However, the effects of the nutritional deficiency of B on the cortical bone tissue of the appendicular skeleton have not yet been described. Thus, a study was performed to histomorphometrically evaluate the density of osteocyte lacunae of cortical bone of mouse femora under conditions of nutritional deficiency of B and to analyze the effects of the deficiency on the biomechanical properties of mouse tibiae. Weaning, 21-day-old male Swiss mice were assigned to the following two groups: controls (B+; n = 10) and experimental (B-; n = 10). Control mice were fed a basal diet containing 3mg B/kg, whereas experimental mice were fed a B-deficient diet containing 0.07mg B/kg for 9weeks. The histological and histomorphometric evaluations of the mice fed a B-deficient diet showed a decrease in the density of osteocyte lacunae in the femoral cortical bone tissue and the evaluation of biomechanical properties showed lower bone rigidity in the tibia.

Flagella-Associated WDR-Containing Protein CrFAP89 Regulates Growth and Lipid Accumulation in Chlamydomonas reinhardtii.

WD40-repeat (WDR) domain-containing proteins are subunits of multi-protein E3 ligase complexes regulating various cellular and developmental activities in eukaryotes. Chlamydomonas reinhardtii serves as a model organism to study lipid metabolism in microalgae. Under nutrition deficient conditions, C. reinhardtii accumulates lipids for survival. The proteins in C. reinhardtii flagella have diverse functions, such as controlling the motility and cell cycle, and environment sensing. Here, we characterized the function of CrFAP89, a flagella-associated WDR-containing protein, which was identified from C. reinhardtii nitrogen deficiency transcriptome analysis. Quantitative real time-PCR showed that the transcription levels of CrFAP89 were significantly enhanced upon nutrient deprivation, including nitrogen, sulfur, or iron starvation, which is considered an effective condition to promote triacylglycerol (TAG) accumulation in microalgae. Under sulfur starvation, the expression of CrFAP89 was 32.2-fold higher than the control. Furthermore, two lines of RNAi mutants of CrFAP89 were generated by transformation, with gene silencing of 24.9 and 16.4%, respectively. Inhibiting the expression of the CrFAP89 gene drastically increased cell density by 112–125% and resulted in larger cells, that more tolerant to nutrition starvation. However, the content of neutral lipids declined by 12.8–19.6%. The fatty acid content in the transgenic algae decreased by 12.4 and 13.3%, mostly decreasing the content of C16:0, C16:4, C18, and C20:1 fatty acids, while the C16:1 fatty acid in the CrFAP89 RNAi lines increased by 238.5 to 318.5%. Suppressed expression of TAG biosynthesis-related genes, such as CrDGAT1 and CrDGTTs, were detected in CrFAP89 gene silencing cells, with a reduction of 16–78%. Overall our results suggest that down-regulating of the expression of CrFAP89 in C. reinhardtii, resulting in an increase of cell growth and a decrease of fatty acid synthesis with the most significant decrease occurring in C16:0, C16:4, C18, and C20:1 fatty acid. CrFAP89 might be a regulator for lipid accumulation in C. reinhardtii.

Optimization of 4-Nitrophenol Degradation by an Isolated Bacterium Anthrobacter sp. and the Novel Biodegradation Pathways under Nutrition Deficient Conditions

To systematically understand the effects of the culturing properties and biodegradation reactions on 4-nitrophenol (PNP)-degrading microorganisms, the bacterium YUP-3 was isolated from soil samples with no PNP-pollution history using a novel method. This bacterium was domesticated to utilize PNP as the sole source of carbon and nitrogen in mineral salt medium. Response surface methodology (RSM) was used to select the most important variables from the simultaneous study on PNP degradation after 48 h incubation. The theoretical maximum PNP degradation of 100.0% was obtained under optimized conditions, and temperature and PNP initial concentrations were concluded to be significant variables. Under carbon- and nitrogen-deficient conditions, five metabolic products of PNP were identified through gas chromatography–mass spectrometry. Hydrogenation and deoxidation were analyzed as two main reactions through PNP degradation to produce hydroquinone. These results demonstrated the importance of the novel PNP degradation pathway under nutrition deficient conditions and the potential use of this highly effective PNP degrading bacterium.

Trinexapac-ethyl causes stimulatory effect on eucalyptus initial growth under nutritional deficiency

Eucalyptus plants are sensitive to abiotic stresses in their initial growth, and nutritional deficiency is one of the most recurrent among them. Trinexapac-ethyl, which is a plant growth regulator, can positively affect eucalyptus, a response known as hormesis, possibly providing plants with greater tolerance to stress. The objective of this study was to evaluate the effect of trinexapac-ethyl at two application times, before planting (BP) or after planting (AP), in Eucalyptus urophylla under conditions of nutritional deficiency (NPK). Two experiments (one for each application time) were conducted simultaneously during 81 days after planting of eucalyptus in 15 L pots. The treatments consisted of three doses of trinexapac-ethyl (0, 30, and 60 g a.i.·ha−1) and four variations of nutrient supply: complete solution (NPK) and solutions without nitrogen (−N), without phosphorus (−P), and without potassium (−K). The variables of gas exchange, growth, and dry matter were evaluated. For both application times, trinexapac-ethyl had a positive effect on the root–shoot ratio of plants grown in −N and also positively affected some eucalyptus photosynthetic characteristics. In the AP application, the compound provided gains in height and dry matter, regardless of the nutrient supply. Under phosphorus deficiency, trinexapac-ethyl provided gains in total dry matter (BP) and leaf area (AP).

Functions of two Malus hupehensis (Pamp.) Rehd. YTPs (MhYTP1 and MhYTP2) in biotic- and abiotic-stress responses

RNA binding proteins play important roles in plant responses to biotic and abiotic stresses. The YT521-B homology (YTH) domain-containing RNA binding protein (YTP) was first found in Rattus norvegicus and is related to oxygen-deficient stress. The Malus YTP gene family has 15 members. Results from their functional analysis will help researchers improve stress tolerance and fruit quality in apple. We cloned two homologous YTP family members in M. hupehensis – MhYTP1 and MhYTP2 – and identified their promoter regions that contain many cis-elements related to biotic and abiotic stresses. Both MhYTP1 and MhYTP2 can be induced by various treatments, e.g., methyl jasmonate (MeJA), salicylic acid (SA), abscisic acid (ABA), water-logging, water deficits, and high salinity. When compared with the wild type (WT), transgenic plants of ‘GL-3’ (‘Royal Gala’) apple that over-express MhYTP1 or MhYTP2 are more sensitive to D. mali infection, heat stress, and high salinity, more resistant to water-logging, chilling, drought and nutrition deficient conditions. All of these findings indicate that MhYTP1 and MhYTP2 participate in various biotic- and abiotic-stress responses.

Development of a Direct Headspace Collection Method from Arabidopsis Seedlings Using HS-SPME-GC-TOF-MS Analysis.

Plants produce various volatile organic compounds (VOCs), which are thought to be a crucial factor in their interactions with harmful insects, plants and animals. Composition of VOCs may differ when plants are grown under different nutrient conditions, i.e., macronutrient-deficient conditions. However, in plants, relationships between macronutrient assimilation and VOC composition remain unclear. In order to identify the kinds of VOCs that can be emitted when plants are grown under various environmental conditions, we established a conventional method for VOC profiling in Arabidopsis thaliana (Arabidopsis) involving headspace-solid-phase microextraction-gas chromatography-time-of-flight-mass spectrometry (HS-SPME-GC-TOF-MS). We grew Arabidopsis seedlings in an HS vial to directly perform HS analysis. To maximize the analytical performance of VOCs, we optimized the extraction method and the analytical conditions of HP-SPME-GC-TOF-MS. Using the optimized method, we conducted VOC profiling of Arabidopsis seedlings, which were grown under two different nutrition conditions, nutrition-rich and nutrition-deficient conditions. The VOC profiles clearly showed a distinct pattern with respect to each condition. This study suggests that HS-SPME-GC-TOF-MS analysis has immense potential to detect changes in the levels of VOCs in not only Arabidopsis, but other plants grown under various environmental conditions.

Potassium starvation-induced oxidative stress and antioxidant defense responses in Brassica juncea

In this study, changes in growth, chlorophyll pigments, proline, hydrogen peroxide (H2O2) and malondialdehyde (MDA) contents, and antioxidative enzyme activities were investigated in the seedlings of four different cultivars (cvs) of mustard [Brassica juncea (L.) Czern. & Coss.], i.e. Varuna, RH-30, Rohini, and Vaibhave under potassium (K) nutrition-deficient conditions. K deficiency induced a significant decrease in concentrations of photosynthetic pigments in all four cvs, however, this decrease was higher in cvs. Varuna and RH-30. During K deficiency, proline concentration increased in all mustard cvs, but a maximum increase in this parameter was shown by cvs. Varuna and RH-30. The activity of the key proline metabolizing enzyme γ-glutamyl kinase increased more in cvs. Varuna and RH-30 compared to cvs. Rohini and Vaibhave. The proline oxidase activity showed greater increase in cvs. Vaibhave and Rohini compared to cvs. Varuna and RH-30. K deficiency increased the concentrations of H2O2 and the activities of anti-oxidative defense system enzymes like superoxide dismutase (SOD), catalase (CAT), ascorbate peroxidase (APX), and glutathione reductase (GR) in the seedlings of all mustard cvs, but higher activities of these enzymes were observed in cvs. Varuna and RH-30 compared to cvs. Rohini and Vaibhave. A significant lipid peroxidation in terms of MDA contents was also observed in the K-deficient seedlings of all four mustard cvs. This study suggests that K-starvation-induced oxidative stress through the high generation of reactive oxygen species (ROS). All mustard cvs counteracted to some extent the effects of ROS by activation of antioxidant machinery. Overall, the results indicate that of all four mustard cvs, Varuna and RH-30 were tolerant to K deficiency.

Production of tumor necrosis factor-α from porcine nucleus pulposus cells at various time points in cell culture under conditions of nutritional deficiency

Nucleus pulposus (NP) in the epidural space induces spinal nerve damage not only by mechanical but also chemical mechanism. NP has been shown to be capable of producing tumor necrosis factor-α (TNF). TNF may play key roles in the NP-induced chemical damage. One of the main pathways to reach the avascular NP is diffusion from the blood supply of the vertebral body through the cartilage endplate. On disk herniation, when NP moves to the epidural space, the distance from the endplate to the herniated NP are longer in the herniated disk than in the intact disk. That is, it seems more difficult to receive adequate nutritional supply from the endplate in the sequestrated type. However, there have been only a few reports of the appearance of TNF in NP. The present study was performed to investigate TNF production in porcine NP under conditions of nutritional deficiency. NP cells were cultured and processed for immunohistochemistry using antisera to TNF, and for ELISA to measure TNF production. The latter was compared longitudinally. The immunoreactivity increased over time. On the other hand, the results of ELISA showed a peak in TNF production 12 h, and lower amounts 1 day and 2 days after application of PBS. These observations may suggest that a nutritional deficit is a possible turn-on switch for TNF up-regulation in the NP.

Nutritional deficiency, starvation, and tissue antioxidant status

Tissue antioxidant status may be compromised under conditions of dietary restriction, either as the result of a deficiency in a specific cofactor required by a particular antioxidant enzyme or of more complex alterations of a generalized nature triggered by metabolic responses to starvation. Many similarities exist between insulin-reversible abnormalities in tissue antioxidant enzyme activities seen in experimental diabetes and in animals subjected to food deprivation-induced weight loss which is associated with hypoinsulinemia. The complex alterations in tissue antioxidant enzyme activities resulting from nutritional deficiency states, disease or drug administration may have important clinical consequences. Free radical-related processes have been implicated in the pathology of certain conditions in which weight loss is frequently recommended (e.g., diabetes and atherosclerosis). It will be important to investigate possible adverse effects of this intervention on the underlying disease process involved. Glutathione-dependent hepatic detoxification processes are impaired under conditions of nutritional deficiency. This finding not only has important clinical implications but the standard practice of fasting small laboratory animals overnight to ensure reliable drug absorption can markedly influence the results of pharmacological/toxicological experiments. Further studies of the influence of nutritional status on free radical-related processes are likely to yield valuable information which may be applicable to a variety of research and clinical problems.