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1.
Oecologia ; 191(4): 803-815, 2019 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-31673766

RESUMO

Central to understanding animal ecology is how prey cope with the interacting risks of starvation and predation. This trade-off is modulated by the energy requirements of prey, yet relatively few studies have incorporated physiological mechanisms for energy savings when considering the behavioural response of prey to predation risk. In our study, we aimed to determine individual variation in behaviour, resting metabolism, body temperature and response to 24-h starvation within a captive population of fat-tailed dunnarts (Sminthopsis crassicaudata; 15-g insectivorous marsupials), and then, using semi-outdoor enclosures, test whether foraging effort and thermal energetics are adjusted in response to manipulation of ground cover, which for small mammals can simulate predation risk. We found that, under the low cover (high predation risk) treatment, dunnarts consumed less food and employed a greater daily reduction in body temperature between their active and rest phase. This result supports the hypothesis that rest-phase thermoregulatory energy savings are employed, even when food is available, if predation risk is perceived to increase the cost of foraging. Individuals exhibited correlated variation along two orthogonal axes incorporating the measured behavioural and metabolic variables, but these differences were not correlated with responses to starvation and predation risk. Our experiment demonstrates that flexibility in daily energy requirements provided by heterothermy can have important consequences for how small mammals respond to both starvation and predation risks. Such challenges are amplified in degraded habitat with introduced predators, making the capacity for heterothermy an even more important mechanism for survival.


Assuntos
Marsupiais , Inanição , Animais , Temperatura Corporal , Ecossistema , Comportamento Predatório
2.
Medicine (Baltimore) ; 98(41): e17434, 2019 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-31593098

RESUMO

RATIONALE: Preoperative prolonged fasting may cause starvation ketoacidosis. Herein, we report of a case of starvation ketoacidosis due to long-term fasting before surgery. PATIENT CONCERNS: We report of a case of metabolic acidosis due to prolonged fasting in a previously healthy 44-year-old woman during a total laparoscopic hysterectomy. Hyperventilation was observed to occur when the surgery was completed. Metabolic acidosis and hypoglycemia were demonstrated by blood gas analysis of the radial artery. DIAGNOSIS: Metabolic acidosis. INTERVENTIONS: The patient received sodium bicarbonate and 5% glucose fluid at the end of the surgery. OUTCOMES: The tracheal tube was successfully removed when the tidal volume of the patient returned to normal after the therapy. However, the patient suffered pulmonary edema when she was transferred to the intensive care unit (ICU). With treatments with furosemide and sodium bicarbonate, acidosis and pulmonary edema were completely corrected at 8 hours after the surgery. On the second day after the surgery, the patient suffered nausea and vomiting. Nausea and vomiting were not completely relieved on the sixth day after the operation; therefore, the patient was transferred to the Department of Gastroenterology for further therapy. LESSONS: This case suggests that although the concept of enhanced recovery after surgery (ERAS) has been adopted by most physicians because of its positive outcomes, the issue of prolonged fasting still exists, and such patients may be exposed to the risk of starvation ketoacidosis.


Assuntos
Acidose/etiologia , Jejum/efeitos adversos , Inanição/complicações , Adulto , Feminino , Humanos , Histerectomia , Período Pré-Operatório
4.
Sci Total Environ ; 695: 133897, 2019 Dec 10.
Artigo em Inglês | MEDLINE | ID: mdl-31425978

RESUMO

The starvation is a common and severe stress for animal survival and development. In aquatic environment, many fish suffer starvation stress in different extent because of the natural migration or feed limitation. When subjected to starved conditions, organisms will employ various adaptive physiological, biochemical, and behavioral changes to regulate metabolism and maintain homeostasis. In the present study, adult female zebrafish were deprived of feed for 1 to 3 weeks to detect the starved effects on adults and larvae. The results showed that biological indexes, RNA/DNA ratios, and nutritional indexes significantly decreased in the female fish after starvation. The number of mature follicles reduced while the average spawning diameter of oocytes increased. For the larvae, the maternal starvation stress distinctly delayed embryonic hatching, decreased larval body length, disrupted larval swimming ability, and reduced survival rate at early-life stages. Furthermore, we found that DNA methylation might conduce to the downregulated mRNA expression of anti-Müllerian hormone and cytochrome P450 aromatase in retarded ovaries under starved conditions. Significant effects on autophagic transcription were shown in maternal ovary and larvae responded to starvation stress. Taken together, our study systematically revealed the reproductive impairments of starvation stress and would facilitate the investigation of environmental stress in teleost fish.


Assuntos
Estresse Fisiológico/fisiologia , Peixe-Zebra/fisiologia , Animais , Feminino , Larva/fisiologia , Inanição
5.
Food Chem ; 299: 125140, 2019 Nov 30.
Artigo em Inglês | MEDLINE | ID: mdl-31299520

RESUMO

Pigment-depletion in the fillets of farmed Atlantic salmon (Salmo salar) arises after periods of elevated water temperatures with voluntary starving. This study tested the effects of dietary pre-loading with different pigment carotenoids (astaxanthin and/or canthaxanthin) combined with two α-tocopherol levels (normal and high: 500 and 1000 mg/kg, respectively) on pigment-depletion in vivo in Atlantic salmon after four weeks of challenge. We also tested whether oxidative stress manifested as an underlying depletion mechanism. Carotenoid levels in whole fillet homogenates were not decreased significantly post-challenge but fillet α-tocopherol concentrations were increased significantly in contrast to decreased oxidative stress indices. However, image analysis revealed localised fillet pigment-depletion following all dietary treatments. These data imply that localised pigment-depletion was not prevented by pre-loading of the fillet with different carotenoid-types/mixtures and increased of α-tocopherol levels from normal to high, respectively. Further, we suggest that oxidative stress might not facilitate pigment-depletion in vivo.


Assuntos
Cantaxantina/metabolismo , Pigmentos Biológicos/metabolismo , Salmo salar/fisiologia , alfa-Tocoferol/metabolismo , Fenômenos Fisiológicos da Nutrição Animal , Animais , Aquicultura/métodos , Cantaxantina/análise , Dieta , Feminino , Produtos Pesqueiros/análise , Estresse Oxidativo , Pigmentação , Inanição , Temperatura Ambiente , Xantofilas/análise , Xantofilas/metabolismo
6.
Environ Pollut ; 252(Pt A): 14-20, 2019 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-31146228

RESUMO

Various crustaceans are farmed using aquaculture, and food deprivation or fasting can occur due to changing of environmental or management strategies. However, the molecular mechanisms underlying responses to starvation in crustaceans remain unclear. To address this, 12 hepatopancreas transcriptomes were compared for oriental river prawn (Macrobrachium nipponense) from four fasting stages (0, 7, 14 and 21 d). Gene Ontology functional annotation and Kyoto Encyclopaedia of Genes and Genomes pathway enrichment analysis of differentially expressed genes were subsequently performed. During the early stages of starvation (0-7 d), drug metabolism via the cytochrome P450 pathway and metabolism of xenobiotics by the cytochrome P450 pathway were enriched, suggesting that they metabolised compounds generated under starvation stress. As starvation proceeded (7-14 d), the retinol (vitamin A) metabolism pathway was activated, based on three up-regulated genes (CYP3, ADH and UGT), along with the two p450 pathways. Meanwhile, vitamin A was gradually consumed. As acute starvation was reached (14-21 d), vitamin A deficiency decreased the mRNA expression levels of IGF-I that is involved in the mTOR signalling pathway, which ultimately affected the growth and development of M. nipponense. Our results implicate drug/xenobiotic metabolism by cytochrome P450s in adaptation to starvation stress. Furthermore, metabolic cascades (CYP and retinol pathways) and growth (mTOR signalling) pathways are clearly triggered in crustaceans during starvation. The findings expand our understanding of the genes associated with hepatopancreas functioning in M. nipponense, and the underlying molecular mechanisms that govern the responses of crustaceans to starvation stress.


Assuntos
Hepatopâncreas/fisiologia , Palaemonidae/genética , Inanição/fisiopatologia , Estresse Fisiológico/fisiologia , Transcriptoma/genética , Aclimatação , Animais , Sistema Enzimático do Citocromo P-450/genética , Sistema Enzimático do Citocromo P-450/metabolismo , Palaemonidae/fisiologia , Transdução de Sinais , Serina-Treonina Quinases TOR/genética , Serina-Treonina Quinases TOR/metabolismo , Vitamina A/metabolismo
7.
Chem Biol Interact ; 306: 104-109, 2019 Jun 01.
Artigo em Inglês | MEDLINE | ID: mdl-30998906

RESUMO

Autophagy is a dynamic recycling process that eliminates damaged proteins and cellular organelles to maintain cellular homeostasis. Aldose reductase (AR) catalyzes conversion of glucose to sorbitol. It also catalyzes the reduction of a broad array of saturated and unsaturated aldehydes. Recently we demonstrated that deletion of AR promotes pathological cardiac remodeling via excessive autophagy; however, the role of AR in starvation-induced autophagy has not been determined. To determine the role of AR in starvation-induced autophagy, WTC57/Bl6 mice were pretreated with the AR inhibitor sorbinil (0.2 g/L for 48 h) in drinking water, followed by 24 h fasting. We found that the sorbinil pretreatment in fed mice did not affect blood glucose levels, whereas, it decreased the blood glucose levels in fasting mice. In comparison with fed mice, the LC3II formation and LCII/LCI ratio were increased in the fasted mice hearts and sorbinil pretreatment further enhanced LC3II formation and LC3II/LC3I ratios in these hearts. Fasting-induced autophagy coincided with AMPK activation in the sorbinil pretreated fasted mice hearts. Autophagy and activation of AMPK was also induced in the gastrocnemius skeletal muscle of sorbinil pre-treated fasted mice. Induction of autophagy in the cardiac tissues of sorbinil pretreated fasted mice was accompanied by increased clearance of 4-hydroxytrans-2-nonenal-protein adducts. Taken together, these results indicate that the inhibition of AR during fasting activates autophagic response, increases clearance of aldehyde-protein adducts, which could serve as a mechanism to maintain cellular homeostasis during starvation.


Assuntos
Aldeído Redutase/antagonistas & inibidores , Aldeídos/metabolismo , Autofagia/efeitos dos fármacos , Imidazolidinas/farmacologia , Inanição , Aldeído Redutase/metabolismo , Animais , Masculino , Camundongos , Camundongos Endogâmicos C57BL
8.
Endocr Pract ; 25(4): 299-305, 2019 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-30995429

RESUMO

Objective: To assess the association between famine exposure in early life and osteoporosis in adulthood. Methods: A total of 2,292 participants born between 1955 and 1965 in Fujian Province were selected; after 3 years, 1,378 participants attended a follow-up research visit. Calcaneus bone mineral density and bone quality were measured by quantitative ultrasound. The T-score was used to assess bone mineral density, and the parameters quantitative ultrasound index (QUI), speed of sound (SOS), and broadband ultrasonic attenuation (BUA) were used to assess bone quality. A T-score threshold of -1.8 was defined as osteoporosis, and a possible vertebral fracture was considered as a prospective height loss of 0.8 inches or more. Results: Compared with the nonexposed cohort, risks of osteoporosis for fetal-, early childhood, and mid-childhood famine-exposed cohorts in postmenopausal women were adjusted odds ratio (OR), 3.741 (95% confidence interval [CI], 1.233, 11.44) versus OR 2.894 (95% CI, 0.997, 8.571) versus OR 4.699 (95% CI, 1.622, 13.612) by logistic regression but not significant in men. Moreover, the fetal-exposed cohort had a weak negative relation with QUI (ß, -5.07 [-10.226, 0.127]) and BUA (ß, -4.321 [-0.88, 0.238]). The early- and mid-childhood-exposed cohorts had significantly lower QUI (ß, -7.085 [-11.799, -2.372] versus ß, -10.845 [-15.68, -6.01]) and BUA (ß, -6.381 [-10.515, -2.246] versus ß, -8.573 [-12.815, -4.331]) than the nonexposed cohort by linear regression. None of the famine-exposed cohorts had a significant relationship with SOS. Conclusion: Famine exposure during early life is associated with higher risk of osteoporosis in adulthood, which is most obvious in postmenopausal women. Furthermore, famine exposure in early life has adverse effects on bone quality. Abbreviations: BMD = bone mineral density; BUA = broadband ultrasonic attenuation; CI = confidence interval; OR = odds ratio; QUI = quantitative ultrasound index; QUS = quantitative ultrasound; SOS = speed of sound.


Assuntos
Osteoporose , Absorciometria de Fóton , Densidade Óssea , Feminino , Humanos , Masculino , Estudos Prospectivos , Inanição
9.
Isr Med Assoc J ; 21(4): 237-240, 2019 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-31032563

RESUMO

BACKGROUND: Throughout history, studies on episodes of famine have led to the discovery of metabolic abnormalities and hormonal aberrations as well as an increased incidence of cancer and mental health conditions. Starvation during early life is thought to nfluence the programming of childhood and adult bone metabolism, which may result in poor bone health in later life. This observational case series includes a small group (with no control group) of famine-exposed Holocaust survivors and their descendants. We proposed an investigational mechanism to determine any association between starvation and osteoporosis, both in the individual survivors and in their descendants.


Assuntos
Holocausto , Osteoporose/epidemiologia , Inanição/epidemiologia , Sobreviventes/estatística & dados numéricos , Adulto , Idoso , Austrália/epidemiologia , Causalidade , Comorbidade , Feminino , Humanos , Hungria/etnologia , Israel/epidemiologia , Judeus/estatística & dados numéricos , Masculino , Pessoa de Meia-Idade , Fatores de Risco , Romênia/etnologia , Eslovênia/etnologia , II Guerra Mundial
10.
Nutrients ; 11(4)2019 Apr 22.
Artigo em Inglês | MEDLINE | ID: mdl-31013668

RESUMO

Undernutrition during early life may lead to obesity in adulthood. This study was conducted to examine the relationship between famine exposure during early life and the risk of abdominal obesity in adulthood. A total of 18,984 and 16,594 adults were surveyed in 2002 and 2010-2012 in two nationally representative cross-sectional surveys, namely China Nutrition and Health Survey, respectively. The risk of abdominal obesity was evaluated for participants born during 1956-1961 and compared with that of participants born during 1962-1964. The overall prevalence of abdominal obesity in adulthood showed a positive association with famine exposure during early life. The odds ratios of famine exposure were 1.31 (1.19-1.44) and 1.28 (1.17-1.40) in 2002 during fetal life and infancy and 1.09 (1.00-1.19) in 2012 during fetal life, respectively. The relationships between famine exposure and abdominal obesity across the famine exposure groups were distinct among females and those who lived in urban areas and were physical inactive (p < 0.05). Exposure to famine during early life was associated with increased risks of abdominal obesity in adulthood, which was partially alleviated by healthy lifestyle factors (e.g., physical activity).


Assuntos
Obesidade Abdominal/epidemiologia , Obesidade Abdominal/etiologia , Inanição , Idoso , China/epidemiologia , Estudos Transversais , Feminino , Humanos , Masculino , Inquéritos Nutricionais , Estado Nutricional , Gravidez , Efeitos Tardios da Exposição Pré-Natal , Fatores de Risco
11.
Oncol Rep ; 41(6): 3555-3564, 2019 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-31002368

RESUMO

Neoplastic transformation is characterized by metabolic rewiring to sustain the elevated biosynthetic demands of highly proliferative cancer cells. To obtain the precursors for macromolecule biosynthesis, cancer cells avidly uptake and metabolize glucose and glutamine. Thus, targeting the availability or metabolism of these nutrients is an attractive anticancer therapeutic strategy. To improve our knowledge concerning how cancer cells respond to nutrient withdrawal, the response to glutamine and/or glucose starvation was studied in human in vitro transformed fibroblasts, deeply characterized at the cellular and molecular level. Concomitant starvation of both nutrients led to rapid loss of cellular adhesion (~16 h after starvation), followed by cell death. Deprivation of glucose alone had the same effect, although at a later time (~48 h after starvation), suggesting that glucose plays a key role in enabling cell attachment to the extracellular matrix. Glutamine deprivation did not induce rapid cell death, but caused a prolonged arrest of cellular proliferation; the cells started dying only 96 h after starvation. Before massive cell death occurred, the effects of all the starvation conditions were reversible. Autophagy activation was observed in cells incubated in the absence of glucose for more than 48 h, while autophagy was not detected under the other starvation conditions. Markers of apoptotic cell death, such as caspase 3, caspase 9 and poly(ADP­ribose) polymerase 1 (PARP­1) proteolytic fragments, were not observed under any growth condition. Glucose and/or glutamine deprivation caused very rapid PARP­1 activation, with marked PARP­1 (poly­ADP) ribosylation and protein (poly­ADP) ribosylation. This activation was not due to starvation­induced DNA double­strand breaks, which appeared at the late stages of deprivation, when most cells died. Collectively, these results highlight a broad range of consequences of glucose and glutamine starvation, which may be taken into account when nutrient availability is used as a target for anticancer therapies.


Assuntos
Proliferação de Células/genética , Transformação Celular Neoplásica/genética , Glucose/metabolismo , Glutamina/metabolismo , Apoptose/genética , Autofagia/genética , Caspases/genética , Caspases/metabolismo , Pontos de Checagem do Ciclo Celular/genética , Morte Celular/genética , Transformação Celular Neoplásica/metabolismo , Quebras de DNA de Cadeia Dupla , Fibroblastos/metabolismo , Fibroblastos/patologia , Glucose/genética , Glutamina/genética , Humanos , Terapia de Alvo Molecular , Poli(ADP-Ribose) Polimerase-1/genética , Poli(ADP-Ribose) Polimerase-1/metabolismo , Inanição/genética , Inanição/metabolismo
12.
Endocr Pract ; 25(6): 598-604, 2019 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-30865536

RESUMO

Objective: Previous studies found that exposure to famine was associated with a higher risk of metabolic syndrome and fatty liver in adult women. In the present study, we investigated the relationship between exposure to the Chinese famine in early life and thyroid function and nodules in adulthood. Methods: We retrospectively analyzed the data of subjects who underwent routine physical check-up in the Public Health Center of our hospital in 2017. Subjects were divided into 3 groups: post-, pre-, and nonexposed groups. The basal metabolic rate (BMR) was estimated by the revised Harris-Benedict formulation. The serum levels of thyroid hormones were detected. Thyroid ultrasonography was performed by experienced technicians. The diagnosis of thyroid nodules was according to the Thyroid Imaging Reporting and Data System (TI-RADS). Results: Compared to nonexposed subjects, the postnatally exposed subjects had a significantly lower level of thyroxine, and statistically higher ultrasensitive thyroid stimulating hormone (P<.05). There was no significant difference in thyroid autoimmune antibodies between groups exposed to the famine and the nonexposed group (P>.05). There were no statistical differences in heart rate and BMR among these groups (P>.05). Exposure to the famine did not affect either the numbers of thyroid nodules, the TI-RADS score of thyroid nodules, or the maximal diameters of thyroid nodules. Conclusion: Our results indicate a significant association between famine exposure in early life and down-regulated thyroid function in adulthood. Postnatal famine exposure may be more vulnerable to nutrient deficiency and lead to restricted thyroid development in later life. Abbreviations: BMR = basal metabolic rate; FT3 = free triiodothyronine; FT4 = free thyroxine; IDD = iodine deficiency disorder; T3 = triiodothyronine; T4 = thyroxine; TG-Ab = thyroglobulin antibody; TI-RADS = Thyroid Imaging Reporting and Data System; uTSH = ultrasensitive thyroid stimulating hormone.


Assuntos
Inanição , Feminino , Humanos , Estudos Retrospectivos , Tireotropina , Tiroxina , Tri-Iodotironina
14.
Anal Chim Acta ; 1059: 59-67, 2019 Jun 20.
Artigo em Inglês | MEDLINE | ID: mdl-30876633

RESUMO

The dielectric properties of cells are directly related to their morphological and physiological properties and can be used to monitor their status when exposed to stress conditions. In this work, dual-frequency dielectrophoresis (DEP) cytometry was employed to measure changes in the membrane capacitance and cytoplasm conductivity of single Chinese hamster ovary (CHO) cells during the progression of starvation-induced apoptosis. Our dual-frequency DEP cytometer enables simultaneous measurement of multiple dielectric properties of single cells and identification of their state (viable or apoptotic) within a heterogeneous sample. We employed one frequency to determine each cell's viability state and the other frequency to characterize the change in membrane capacitance or cytoplasm conductivity. Cells were starved by incubation in a medium lacking glucose and glutamine and monitored every 12 h over a 64 h period. Our results showed a subpopulation of early apoptotic cells emerged after 40 h in the starvation medium, which rapidly increased during the next 12 h. After 52 h, a complete transition from viable to apoptotic state was observed. Analyzing the subpopulation of viable cells over the first 52 h showed that the membrane capacitance gradually declined from an initial value of 2.0 to 1.2 µF/cm2, and was 0.9 µF/cm2 for apoptotic cells. The cytoplasm conductivity of viable cells initially remained constant and then declined from 0.40 to 0.27 S/m after 40 h, coinciding with onset of apoptotic processes. A dramatic decrease in cytoplasm conductivity from 0.27 to 0.07 S/m was observed after 52 h, corresponding to apoptotic cells. As membrane capacitance is related to membrane morphology and cytoplasm conductivity is related to intracellular ion concentrations, the results indicate that during controlled starvation the cell membrane smooths gradually whereas intracellular ion concentrations are initially maintained near homeostatic levels until a later dramatic decline occurs.


Assuntos
Membrana Celular/metabolismo , Citoplasma/metabolismo , Capacitância Elétrica , Condutividade Elétrica , Inanição/metabolismo , Animais , Apoptose/fisiologia , Células CHO/citologia , Cricetulus , Citometria de Fluxo/métodos , Fatores de Tempo
15.
Acta Biochim Pol ; 66(1): 47-59, 2019 Mar 10.
Artigo em Inglês | MEDLINE | ID: mdl-30852584

RESUMO

Acipenser stellatus represents a species of great economical interest due to its roe used for caviar production. Therefore, it has been intensively captured for decades and nowadays, this species is on the verge of extinction. As a consequence, Acipenser stellatus is intensively raised in fish farms. Aquaculture is focused on optimizing the feeding regime of juveniles. The aim of this study was to investigate if Acipenser stellatus can adapt to a starvation/refeeding regime by assessing the effects of this regime on growth performance, oxidative stress biomarkers and heat shock protein (hsp) gene expression in juveniles raised under aquaculture conditions. The juveniles were subjected to two starvation/refeeding regimes: a 7-day starvation period followed by 21 days of refeeding, and a14-day starvation period followed by 21 days of refeeding. The results had shown that the juveniles subjected to 7/21-day starvation/refeeding regime presented a complete compensatory growth, they were able to counteract the oxidative stress by enhancing activities of the antioxidant enzymes and they presented no significant changes in hsp gene expression. In contrast, 14/21-day starvation/refeeding regime negatively influenced growth performance, it induced a high level of oxidative stress that was impossible to counteract and it determined major changes in the hsp gene expression level in the liver of Acipenser stellatus. Thus, Acipenser stellatus seems to be able to adapt only to the 7/21-day starvation/refeeding regime that does not threaten the growth performance and the welfare of juveniles. Therefore, it could be useful to optimize the feeding practice in aquaculture production.


Assuntos
Antioxidantes/metabolismo , Estresse Oxidativo/fisiologia , Inanição/metabolismo , Inanição/fisiopatologia , Animais , Aquicultura , Catalase/metabolismo , Peixes , Glutationa Peroxidase/metabolismo , Glutationa Redutase/metabolismo , Glutationa Transferase/metabolismo , Proteínas de Choque Térmico HSP70/metabolismo , Proteínas de Choque Térmico HSP90/metabolismo , Reação em Cadeia da Polimerase em Tempo Real , Superóxido Dismutase/metabolismo
17.
Proc Natl Acad Sci U S A ; 116(15): 7449-7454, 2019 04 09.
Artigo em Inglês | MEDLINE | ID: mdl-30910968

RESUMO

When mice are subjected to 60% calorie restriction for several days, they lose nearly all of their body fat. Although the animals lack energy stores, their livers produce enough glucose to maintain blood glucose at viable levels even after a 23-hour fast. This adaptation is mediated by a marked increase in plasma growth hormone (GH), which is elicited by an increase in plasma ghrelin, a GH secretagogue. In the absence of ghrelin, calorie-restricted mice develop hypoglycemia, owing to diminished glucose production. To determine the site of GH action, in the current study we used CRISPR/Cas9 and Cre recombinase technology to produce mice that lack GH receptors selectively in liver (L-Ghr -/- mice) or in adipose tissue (Fat-Ghr-/- mice). When subjected to calorie restriction and then fasted for 23 hours, the L-Ghr -/- mice, but not the Fat-Ghr-/- mice, developed hypoglycemia. The fall in blood glucose in L-Ghr-/- mice was correlated with a profound drop in hepatic triglycerides. Hypoglycemia was prevented by injection of lactate or octanoate, two sources of energy to support gluconeogenesis. Electron microscopy revealed extensive autophagy in livers of calorie-restricted control mice but not in L-Ghr -/- mice. We conclude that GH acts through its receptor in the liver to activate autophagy, preserve triglycerides, enhance gluconeogenesis, and prevent hypoglycemia in calorie-restricted mice, a model of famine.


Assuntos
Autofagia , Glicemia/metabolismo , Restrição Calórica , Hormônio do Crescimento/sangue , Hipoglicemia/sangue , Fígado/metabolismo , Inanição/sangue , Animais , Glicemia/genética , Doença Crônica , Modelos Animais de Doenças , Hormônio do Crescimento/genética , Hipoglicemia/genética , Fígado/patologia , Camundongos , Camundongos Knockout , Inanição/genética , Inanição/patologia
18.
Nat Ecol Evol ; 3(4): 702-707, 2019 04.
Artigo em Inglês | MEDLINE | ID: mdl-30911148

RESUMO

Evolutionary ecologists often seek to identify the mechanisms maintaining intraspecific variation. In social animals, whole groups can exhibit between-group differences in their collective traits. We examined whether negative frequency-dependent selection (that is, a rare-type advantage) could help to maintain between-group variation. We engineered neighbourhoods of social spider colonies bearing bold or shy foraging phenotypes and monitored their fecundity in situ. We found that bold colonies enjoyed a rare-type advantage that is lost as the frequency of bold colonies in a neighbourhood increases. The success of shy colonies was not frequency dependent. These dynamics seem to be driven by a foraging advantage of bold colonies that is lost in bold neighbourhoods because prey become scarce, and shy colonies perform better than bold colonies under low-resource conditions. Thus, to understand selection on collective traits, it is insufficient to examine groups in isolation. The phenotypic environment in which groups reside and compete must also be considered.


Assuntos
Comportamento Predatório , Comportamento Social , Aranhas/fisiologia , Animais , Feminino , Fenótipo , Seleção Genética , Inanição
20.
PLoS Biol ; 17(3): e3000199, 2019 03.
Artigo em Inglês | MEDLINE | ID: mdl-30917116

RESUMO

The balance of sleep and wake is plastic and changes to meet environmental demands. Mechanisms that allow an animal to suppress sleep and maintain waking in potentially adverse situations could serve adaptive functions in evolution. The fruit fly, Drosophila melanogaster, is well poised as a system in which to explore these questions. The environment changes sleep and wake in flies, e.g., starvation induces waking in Drosophila as it does in many animals. Further, the sophisticated neurobiological toolkit available to Drosophila researchers gives the fly a great advantage as a system to investigate the precise neurobiological mechanisms underlying these adaptive changes. In a paper in this issue of PLOS Biology, Yurgel and colleagues elegantly exploit the advantages of the Drosophila model to map starvation-induced wakefulness to a single pair of peptidergic neurons and their partners.


Assuntos
Inanição , Vigília , Animais , Drosophila melanogaster , Neurônios , Sono
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