• Molecules and Cells
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• v.44 no.7
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• pp.529-537
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• 2021

Most animals face frequent periods of starvation throughout their entire life and thus need to appropriately adjust their behavior and metabolism during starvation for their survival. Such adaptive responses are regulated by a complex set of systemic signals, including hormones and neuropeptides. While much progress has been made in identifying pathways that regulate nutrient-excessive states, it is still incompletely understood how animals systemically signal their nutrient-deficient states. Here, we showed that the FMRFamide neuropeptide FLP-20 modulates a systemic starvation response in Caenorhabditis elegans. We found that mutation of flp-20 rescued the starvation hypersensitivity of the G protein β-subunit gpb-2 mutants by suppressing excessive autophagy. FLP-20 acted in AIB neurons, where the metabotropic glutamate receptor MGL-2 also functions to modulate a systemic starvation response. Furthermore, FLP-20 modulated starvation-induced fat degradation in a manner dependent on the receptor-type guanylate cyclase GCY-28. Collectively, our results reveal a circuit that senses and signals nutrient-deficient states to modulate a systemic starvation response in multicellular organisms.

• Journal of Marine Life Science
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• v.3 no.2
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• pp.87-95
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• 2018

To investigate effects of starvation on physiological changes, stress response, and survival of cobitid loach (Misgurnus anguillicaudatus) exposed to sodium nitrite (NaNO₂), a 4-week experiment was conducted. Fewer fish survived in the starved group than those in the fed group during the experiment. Starvation resulted in growth retardation, leading to differences in body length and body depth between fed and starved groups. The fed gorup continued to grow and remained in good condition. Blood chemical analysis (plasma cortisol and glucose) showed significant differences in stress response to nitrite exposure between fed and starved groups (p < 0.05). These results suggest that all parameters employed in this study to assess effects of starvation with NaNO₂ stress are useful information for researching nutritional status in cobitid loach.

• Journal of Microbiology
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• v.37 no.3
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• pp.141-147
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• 1999

Thirteen transcriptionally-fused carbon starvation mutants, derived from Pseudomonas putida ATCC 12633, were analyzed for their survivability and transcriptional induction profiles upon carbon starvation. One of these mutants, MK114, which exhibited the lowest survivability and the highest induction rate, was selected and further examined under different starvation (nitrogen and phosphate) and stress (osmolarity, H2O2, salts, alcohol, and heat) conditions. Under all tested conditions MK114 induced ${\beta}$-galactosidase activity, implying that the interrupted gene (cst114) is a general starvation and stress response gene. The rate of induction ranged from 2.6-fold for phosphate starvation to 3.7-fold for osmotic shock. The mini-Tn5 flanking DNA was cloned from the chromosome of MK114. The cloned DNA fragment exhibited carbon starvation activity, indicating that this fragment contains a carbon starvation-related promoter region. This region was partially sequenced. Possible physiological roles of Cst114 in a carbon sensing mechanism and in other stress responses are also discussed.

• Development and Reproduction
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• v.22 no.4
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• pp.319-329
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• 2018

The experiment was conducted for 210 days to determine the effect of feeding, and starvation, and exposure to sodium nitrite ($NaNO_2$) on the survival, physiological changes, hematological parameter, and stress response of Far Eastern catfish, Silurus asotus. The survival of the starved group was lower than that of the fed group during the experiment. Starvation resulted in retardation of growth, which provides an example of fish that failed to continue to grow and remain in a good condition. Blood analyses (cortisol and glucose) showed significant differences of stress response between the fed and starved groups exposed to $NaNO_2$ at the conclusion of the experiment (p<0.05). These results suggest that all nutritional parameters used for starvation and feeding with $NaNO_2$ stress in this experiment appear to be a useful index of nutritional status in Far Eastern catfish.

• Proceedings of the Korean Society of Crop Science Conference
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• 2017.06a
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• pp.174-174
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• 2017

To cope with phosphate (Pi) deficient stress, plants modulate various physiological and developmental processes, such as gene expression, Pi uptake and translocation, and root architecture changes. Here, we report the identification and characterization of novel activation-tagged mutant involved in Pi starvation signaling in Arabidopsis. The hpd (${\underline{h}ypersensitive}$ to ${\underline{P}i}$ $ {\underline{d}eficiency}$) mutant exhibits enhanced phosphate uptake and altered root architectural change under Pi starvation compared to wild type. Expression analysis of auxin-responsive DR5::GUS reporter gene in hpd mutant indicated that auxin translocation in roots under Pi starvation are suppressed in hpd mutant plants. Impaired auxin translocation in roots of hpd mutant was attributable to abnormal root architecture changes in Pi starvation conditions. Our results indicated that abnormal auxin translocation in hpd mutant might be due to mis-regulation of auxin efflux carrier proteins, PIN-FORMED (PIN) 1, and 2 under Pi starvation conditions. Not only expression levels but also expression domains of PIN proteins were altered in hpd mutant in response to Pi starvation. Molecular genetic analysis of hpd mutant revealed that the mutant phenotype is caused by the lesion in ENHANCED SILENCING PHENOTYPE4 (ESP4) gene whose function is proposed in mRNA 3'-end processing. The results suggest that mRNA processing plays crucial roles in Pi homeostasis as well as developmental reprograming in response to Pi deprivation in Arabidopsis.

• Molecules and Cells
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• v.40 no.10
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• pp.697-705
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• 2017

The maintenance of inorganic phosphate (Pi) homeostasis is essential for plant growth and yield. Plants have evolved strategies to cope with Pi starvation at the transcriptional, post-transcriptional, and post-translational levels, which maximizes its availability. Many transcription factors, miRNAs, and transporters participate in the Pi starvation signaling pathway where their activities are modulated by sugar and phytohormone signaling. Environmental stresses significantly affect the uptake and utilization of nutrients by plants, but their effects on the Pi starvation response remain unclear. Recently, we reported that Pi starvation signaling is affected by abiotic stresses such as salt, abscisic acid, and drought. In this review, we identified transcription factors, such as MYB, WRKY, and zinc finger transcription factors with functions in Pi starvation and other environmental stress signaling. In silico analysis of the promoter regions of Pi starvation-responsive genes, including phosphate transporters, microRNAs, and phosphate starvation-induced genes, suggest that their expression may be regulated by other environmental stresses, such as hormones, drought, cold, heat, and pathogens as well as by Pi starvation. Thus, we suggest the possibility of cross-talk between Pi starvation signaling and other environmental stress signaling pathways.

• Journal of Microbiology and Biotechnology
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• v.24 no.9
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• pp.1207-1215
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• 2014

Candida albicans, the major human fungal pathogen, undergoes morphological transition from the budding yeast form to filamentous growth in response to nitrogen starvation. In this study, we identified a new function of GST2, whose expression was required for filamentous growth of C. albicans under nitrogen-limiting conditions. The Gst2p showed Gst activity and required response to oxidative stress. The ${\Delta}gst2$ mutant displayed predominantly yeast phase growth in low ammonium media. Such morphological defect of ${\Delta}gst2$ mutants was not rescued by overexpression of Mep2p, Cph1p, or Efg1p, but was rescued by either overexpression of a hyperactive $RAS1^{G13V}$ allele or through exogenous addition of cyclic AMP. In addition, the ${\Delta}gst2$ mutants had lower levels of RAS1 transcripts than wild-type cells under conditions of nitrogen starvation. These results were consistent with the Ras1-cAMP pathway as a possible downstream target of Gst2p. These findings suggest that Gst2p is a significant component of nitrogen starvation-induced filamentation in C. albicans.

• Plant Biotechnology Reports
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• v.5 no.4
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• pp.309-315
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• 2011

Rice grown in anaerobic waterlogged soil accumulates ammonium as a major source of nitrogen (N). We have compared the physiological symptoms of rice seedlings subjected to N-starvation stress with those receiving sufficient N, based on measurements of shoot/root length and weight and an analysis of protein expression patterns. N starvation marginally increased root growth but notably decreased shoot biomass. N uptake was reduced by >50% in the roots and shoots of N-starved seedlings. To better understand the mechanism of N starvation in rice, we performed a comparative proteome analysis of proteins isolated from rice leaves. Twenty-five differentially expressed proteins were analyzed by matrixassisted laser desorption/ionization time-of-flight (TOF) mass spectrometry and electron spray ionization quadrupole TOF. Functional analysis of the N-starvation response proteins suggested their involvement in protein synthesis and fate, metabolism, and defense. These results indicate that these proteins may play important roles in regulating the plant's complex adaptation responses for N use during N starvation. The proteins may be useful for further characterization of protein function in plant N nutrition.

• Asian-Australasian Journal of Animal Sciences
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• v.27 no.9
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• pp.1360-1367
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• 2014

Triplicate groups of fed and starved olive flounder, Paralichthys olivaceus (body weight: $119.8{\pm}17.46$ g), were examined over 42 days for physiological changes using hematological, biochemical, and non-specific immune parameters. No significant differences in concentrations of blood hemoglobin and hematocrit and plasma levels of total cholesterol, aspartate aminotransferase, alanine aminotransferase, glucose, and cortisol were detected between fed and starved groups at any sampling time throughout the experiment. In contrast, plasma total protein concentrations were significantly lower in starved fish than in fed fish from day 7 onwards. Moreover, plasma lysozyme concentrations were significantly higher in starved flounder from day 21 onwards. This result confirms that the response of olive flounder to short-term (less than about 1.5 months) starvation consists of a readjustment of metabolism rather than the activation of an alarm-stress response. The present results indicate that starvation does not significantly compromise the health status of fish despite food limitation.

• Proceedings of the Korean Society of Crop Science Conference
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• 2007.04a
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• pp.65-73
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• 2007

The objective of this study is to understand how regulatory mechanisms respond to sugar status for more efficient carbon utilization and source-sink regulation in plants. So, we need to identify and characterize many components of sugar-response pathways for a better understanding of sugar responses. For this end, genes responding change of sugar status were screened using Arabidpsis cDNA arrays, and confirmed thirty-six genes to be regulated by sucrose supply in detached leaves by RNA blot analysis. Eleven of them encoding proteins for amino acid metabolism and carbohydrate metabolism were repressed by sugars. The remaining genes induced by sugar supply were for protein synthesis including ribosomal proteins and elongation factors. Among them, I focused on three hydrolase genes encoding putative $\beta$-galactosidase, $\beta$-xylosidase, and $\beta$-glucosidase that were transcriptionally induced in sugar starvation. Homology search indicated that these enzymes were involved in hydrolysis of cell wall polysaccharides. In addition to my results, recent transcriptome analysis suggested multiple genes for cell wall degradation were induced by sugar starvation. Thus, I hypothesized that enzyme for cell wall degradation were synthesized and secreted to hydrolyze cell wall polysaccharides producing carbon source under sugar-starved conditions. In fact, the enzymatic activities of these three enzymes increased in culture medium of Arabidopsis suspension cells under sugar starvation. The $\beta$-galactosidase encoded by At5g56870 was identified as a secretory protein in culture medium of suspension cells by mass spectrometry analysis. This protein was specifically detected under sugar-starved condition with a specific antibody. Induction of these genes was repressed in suspension cells grown with galactose, xylose and glucose as well as with sucrose. In planta, expression of the genes and protein accumulation were detected when photosynthesis was inhibited. Glycosyl hydrolase activity against galactan also increased during sugar starvation. Further, contents of cell wall polysaccharides especially pectin and hemicellulose were markedly decreased associating with sugar starvation in detached leaves. The amount of monosaccharide in pectin and hemicellulose in detached leaves decreased in response to sugar starvation. These results supported my idea that cell wall has one of function to supply carbon source in addition to determination of cell shape and physical support of plant bodies.