The regulation of endogeneous energy stores during starvation and refeeding in the somatic tissues of the golden perch

Adult golden perch Macquaria ambigua were fed to satiety, starved for up to 210 days, or starved for 150 days then fed to satiety for 60 days to investigate the utilization of energy stores in response to food deprivation and re-feeding. Golden perch sequentially mobilize energy from hepatic tissue, extra-hepatic lipid, and finally muscle components in response to food deprivation. The relative size of the liver was significantly reduced by 30 days after the onset of food deprivation due to the simultaneous mobilization of lipid, protein and glycogen reserves. These stores were renewed rapidly within 30 days by satiety feeding. Mobilization of lipid stores in perivisceral fat bodies occurred between 30 and 60 days of food deprivation. These deposits were also renewed upon re-feeding, although not as rapidly as liver reserves. The glycogen content of the epaxial muscle was reduced by the 60th day of food deprivation but subsequently increased indicating the mobilization of other energy reserves. The concentration of muscle lipid decreased after 90 days of food deprivation. The only significant response in body composition observed in the fish fed to satiety throughout the study was an increase in the relative size of the perivisceral fat bodies. The results of this study suggest that golden perch are well adapted to cope with extended periods of food deprivation, storing energy as perivisceral fat when food is readily available and having a clearly sequential process for mobilizing energy when food is scarce which largely protects the integrity of the musculature.     

饥饿及再投喂对日本囊对虾糖代谢的影响

研究了日本囊对虾在饥饿和再投喂下血糖、肝胰脏糖原和肌糖原含量的变化.结果表明：在饥饿状态下,日本囊对虾肝胰脏糖原含量和血糖浓度在饥饿开始时迅速下降,肌糖原含量在饥饿10 d时下降到最低值,在饥饿10~15 d时通过糖原异生作用又恢复至最初水平,但随着饥饿时间的延长,糖原含量持续下降.恢复投喂后,肝胰脏糖原含量和肌糖原含量均能得到较好恢复,饥饿10 d和 15 d组的血糖浓度在恢复投喂10 d后显著高于对照组,但饥饿25 d组的血糖浓度始终显著低于对照.表明饥饿时间过长,对血糖浓度的恢复有较大影响     

饥饿和再投喂对虎斑乌贼幼体存活、生长和消化酶活力的影响

本文探究了饥饿胁迫与饥饿后再投喂对虎斑乌贼幼体存活率、生长、行为、肝体比、摄食率以及消化酶活力的影响.在室内控制条件下开展了幼体(初始体质量为4.95±0.48 g)的饥饿(0、1、2、3、4、5、6 d)和再投喂(15 d)试验.结果表明: 不同饥饿时间对虎斑乌贼的幼体存活率、体质量降低率、肝体比和消化酶活力影响显著.随着饥饿胁迫时间的增加,其存活率、肝体比呈下降趋势,其中饥饿3 d后,存活率开始明显下降,体质量降低率明显增大,幼体出现喷墨、互相残杀等异常行为;4种消化酶活力呈先下降后上升的趋势,淀粉酶活力以饥饿4 d组最低 (0.07±0.02 U·mg^-1·prot^-1);脂肪酶活力以饥饿2 d组最低(18.47±2.07 U·g^-1·prot^-1),饥饿6 d组最高(57.60±3.98 U·g^-1·prot^-1),胃蛋白酶活力和胰蛋白酶活力以饥饿5 d组(1.98±0.59 U·mg^-1·prot^-1)和饥饿4 d(186.68±20.72 U·mg^-1·prot^-1) 最低.饥饿处理结束后,经15 d再投喂,各试验组存活率、特定生长率、肝体比和摄食率差异显著,幼体的存活率、特定生长率、肝体比和摄食率均与饥饿处理时间呈负相关;饥饿1和2 d组与对照组的存活率、特定生长率和肝肝体比无显著差异,而饥饿3～6 d组显著低于对照组;饥饿1～2 d组的摄食率明显高于对照组,而饥饿6 d组的摄食率明显小于对照组;各组淀粉酶与脂肪酶活力无显著差异,胃蛋白酶与胰蛋白酶活力差异显著,均以对照组最高(胃蛋白酶活力7.06±0.64 U·mg^-1·prot^-1,胰蛋白酶活力914.67±26.54 U·mg^-1·prot^-1),饥饿6 d组最低(胃蛋白酶活力3.21±0.57 U·mg^-1·prot^-1,胰蛋白酶活力660.04±37.92 U·mg^-1·prot^-1).说明虎斑乌贼的幼体饥饿不可逆点(PNR)为第6天,且不能补偿生长.     

Comparative study of the metabolic responses during food shortage and subsequent recovery at different temperatures in the adult lesser mealworm, Alphitobius diaperinus (Coleoptera: Tenebrionidae)

Metabolic responses to prolonged food shortage (35 days) and subsequent re‐feeding (14 days) were investigated in adults of an introduced beetle, Alphitobius diaperinus Panzer, as a function of temperature (12, 16, 20 and 24 °C). Various qualitative and quantitative changes that greatly vary according to the temperature experienced occurred in metabolite levels during prolonged starvation. Whereas levels of protein and ATP did not change significantly, triglycerides decreased markedly and glycogen changed little. Metabolite levels were differently affected by temperature, with triglycerides being less rapidly degraded at 20 than at 24 °C and almost completely depleted at 12 and 16 °C; in contrast to higher temperatures, glycerol is accumulated at 12 °C. Physiological adaptation to starvation and low temperatures are highly linked and energy allocation for starvation vs. temperature acclimation must be strictly regulated, both being essential for insect survival. Re‐synthesis rates during recovery are probably highly temperature‐dependent for all metabolites. The proteins retained during starvation and the preferential degradation of lipids allowed a rapid recovery. Above 16 °C, adult A. diaperinus regained locomotory activity rapidly and the triglyceride, glycerol and glycogen reserves were restored. This tropical species may be able to colonize other environments such as natural and/or artificial biotopes where conditions are close to those of its natural habitat.     

Selective changes in the protein-turnover rates and nature of growth induced in trout liver by long-term starvation followed by re-feeding

We report upon the effects of a cycle of long-term starvation followed by re-feeding on the liver-protein turnover rates and nature of protein growth in the rainbow trout (Oncorhynchus mykiss). We determined the protein-turnover rate and its relationship with the nucleic-acid concentrations in the livers of juvenile trout starved for 70 days and then re-fed for 9 days. During starvation the total hepatic-protein and RNA contents decreased significantly and the absolute protein-synthesis rate (A_S) also fell, whilst the fractional protein-synthesis rate (K_S) remained unchanged and the fractional protein-degradation rate (K_D) increased significantly. Total DNA content, an indicator of hyperplasia, and the protein:DNA ratio, an indicator of hypertrophy, both fell considerably. After re-feeding for 9 days the protein-accumulation rates (K_G, A_G) rose sharply, as did K_S, A_S, K_D, protein-synthesis efficiency (K_RNA) and the protein-synthesis rate/DNA unit (K_DNA). The total hepatic protein and RNA contents increased but still remained below the control values. The protein:DNA and RNA:DNA ratios increased significantly compared to starved fish. These changes demonstrate the high response capacity of the protein-turnover rates in trout liver upon re-feeding after long-term starvation. Upon re-feeding hypertrophic growth increased considerably whilst hyperplasia remained at starvation levels.     

闽江河口湿地植物氮磷吸收效率的季节变化

以闽江河口湿地土著种芦苇与入侵种互花米草为研究对象,测定了二者地上生物量和氮、磷吸收效率.结果表明：芦苇和互花米草地上生物量的季节变化呈典型的单峰值曲线,芦苇夏季地上生物量最大,达到2195.33 g·m^-2,互花米草则秋季最大,达到3670.02 g·m^-2;不同季节芦苇和互花米草氮、磷吸收效率均呈单峰值曲线,芦苇氮、磷吸收效率分别在夏季和秋季达到最高(21.06 和1.12 g·m^-2),互花米草均在秋季达到峰值(26.76和3.23 g·m^-2);芦苇和互花米草的氮吸收效率极显著大于磷(P<0.01),且互花米草的氮、磷吸收效率显著大于芦苇(P<0.05);植物N/P、C/N和C/P对植物氮、磷吸收效率有一定指示意义.     

哲罗鱼稚鱼最佳投喂策略

为探讨哲罗鱼稚鱼的最佳投喂策略,设置了饥饿再投喂试验、饥饿再投喂恢复试验以及日投喂频率试验.结果表明: 饥饿再投喂试验中,各饥饿组未表现出补偿生长现象.但在饥饿再投喂恢复试验中,各饥饿组表现出不同程度的补偿生长,其中S_1/2组(饥饿1/2 d投喂1/2 d)体质量的增加量与对照组接近,表现出完全补偿生长.表明在哲罗鱼早期稚鱼阶段(体质量0～2 g,水温9～15.3 ℃),S_1/2是可以考虑使用的投喂方法.日投喂频率试验中,T₃组(日投喂3次)体长、体质量的增加量以及特定生长率均最高,饵料转化率也相对较高.表明在哲罗鱼后期稚鱼阶段(体质量2～21 g,水温8.8～15.5 ℃),以日投喂3次为宜.     

Effects of starvation,re-feeding and timing of food supply on daily rhythm features of gut melatonin in carp (Catla catla)

Influences of starvation, re-feeding and time of food supply on daily rhythm features of melatonin (5-methoxy-N-acetyltryptamine) and its key regulator AANAT (arylalkylamine N-acetyltransferase) protein in the gut tissues were separately evaluated in carp Catla catla. The first experiment was aimed at demonstration of duration dependent effects of starvation and re-feeding after starvation on the daily profiles and rhythm features of gut melatonin and AANAT. Accordingly, juvenile carp were randomly distributed in three groups, which were (a) provided with balanced diet daily at a fixed time, that is, 10:00 clock hour or zeitgeber time (ZT) 4 (control), or (b) starved (for 2-, 4-, 6- or 8 days), or (c) initially starved for 8 days and then re-fed (for 2-, 4-, 6-, 8-, 12- or 16 days) daily with the same food and at the time (ZT4) used for control fish. The carp in each group were sampled for collection of gut tissues at six different time points at a regular interval of 4?h in a daily cycle. In another experiment, the influences of timing of food supply were separately examined in four fish groups, which were provided with a fixed amount of food once daily either at 06:00 or 12:00 or 18:00 or 24:00 clock hour corresponding to ZT0 or ZT6 or ZT12 or ZT18, respectively, for 7 days before sampling at 12 different time points with a regular interval of 2?h in a 24-h cycle. The study revealed a gradual increase in the mesor and amplitude values of melatonin and AANAT in gut with the progress of starvation till their values reached maximum at day-6 and remained steady thereafter. In contrast, re-feeding of 8-day starved fish resulted in a sharp decrease in their mesor and amplitude values after 2 days and then followed by a steady-state increase till re-attainment of their values close to control fish at the end of 16 days. The acrophase of these gut variables in each control, starved and re-fed fish was noted mostly at midday or ZT6. However, the results of another experiment demonstrated that a shift of food supply time led to a shift in their acrophase. The amount of residual food in the gut lumen in each, but not starved, fish by showing a significant positive correlation independently with the gut levels of melatonin and AANAT also indicated possible role of food as the synchronizer for their daily rhythms. Collectively, it appears reasonable to argue that daily profiles of gut melatonin and AANAT are strongly influenced by the availability of food, while their daily rhythm features seem to be dependent mostly on the time of food supply in carp.