Does starvation influence the antioxidant status of the digestive gland of Nacella concinna in experimental conditions?

In a previous study we analysed the effect of diesel seawater contamination in the digestive gland of the Antarctic limpet Nacella concinna. We observed that antioxidant enzyme activities decreased after one-week starvation prior to the experiment, and this was considered in the analysis of the obtained results. To know whether the digestive gland oxidant-antioxidant status may be altered by starvation and experimental conditions, we evaluated the food deprivation effect in limpets from the nearshore shallow waters of Potter Cove, Antarctica. Organisms were acclimated to laboratory conditions and were divided in fed and starved groups, and maintained in these conditions during one month. Every week 20 limpets were sampled from each group. Digestive glands were dissected and kept frozen until they were processed. Superoxide dismutase (SOD), catalase (CAT) and glutathione S-transferase (GST) activities, as well as lipid peroxidation (LPO) measured as thiobarbituric reactive substances (TBARS), protein oxidation (PO) and reduced glutathione (GSH) were measured. For both groups of limpets, SOD increased its activity in the first week of the exposure period, with a maximum in the second week. CAT activity increased significantly in the second week, only for the starved group. Similarly, GST activity also increased for starved group in the second week; but maintained this tendency for both groups until the fourth week. In fed and starved limpets, TBARS values increased significantly, during the first week and then returned to normal values. The PO levels in the starved group increased only during the first week. The GSH content, for the fed group, increased significantly after the third week. The obtained results indicate that biochemical or physiological studies conducted with N. concinna should consider the effects of food deprivation and time spent under experimental conditions.     

Physiological and metabolic adjustments of Hoplosternum littorale (Teleostei,Callichthyidae) during starvation

All animals face the possibility of limitations in food resources that could ultimately lead to mortality caused by starvation. The primary goal of this study was to characterize the various physiological strategies that allow fish to survive starvation. A multiparametric approach, including morphological biomarkers, blood plasma metabolites, oxidative stress and energy reserves, was used to assess starvation effects on the fish Hoplosternum littorale. Adult specimens were maintained at four experimental groups: control (fed ad libitum), and starved (not fed) fish for 7 and 28 days. Significant changes were observed not only after 28 days, but also after 7 days of starvation. In the shorter period, the hepatosomatic index as well as plasma triglycerides and glucose were significantly lower in starved fish than in the control ones. These results were accompanied by reduced lipid, glycogen and protein reserves in liver and diminished glycogen content in muscle, suggesting the need of these macromolecules as fuel sources. In addition, increased antioxidant enzyme activities were observed in gills, without evidence of oxidative stress in any of the evaluated tissues. Most significant differences were found in 28-days starved fish: total body weight together with the hepatosomatic index was lower when compared to control fish. The plasmatic metabolites tested (glucose, triglyceride, cholesterol and protein), all energy reserves in liver and glycogen content in muscle decreased in 28-days starved fish. Lipid oxidative damage was reported in liver, kidney and brain, and antioxidant enzymes (GST, GR, GPx and CAT) were activated in gills. According to the multivariate analysis, oxidative stress markers and metabolic parameters were key biomarkers that contributed in separating starved from fed fish. Our study allowed an integrated assessment of the fish response to this particular condition.     

饥饿胁迫对麦长管蚜有翅成蚜能量物质含量的影响

【目的】分析饥饿胁迫下麦长管蚜Sitobion avenae(Fabricius)的能量物质含量变化,以期从生理生化角度为蚜虫饥饿胁迫下的能量适应机制提供依据。【方法】以取食小麦苗的麦长管蚜为对照,测定饥饿胁迫下麦长管蚜有翅成蚜的鲜重、干重、含水量、可溶性糖、糖原、总脂和可溶性蛋白质含量变化,通过这些不同生化物质含量之间的相关关系,分析饥饿胁迫下麦长管蚜的能量代谢特点。【结果】麦长管蚜饥饿组鲜重和干重均低于羽化后同一时间取食个体,前者范围分别为5.30~8.73和1.67~3.10 mg/20头,后者分别为7.93~8.73和2.53~3.10 mg/20头;饥饿组和取食组含水量范围分别为63.16%~71.76%和63.25%~67.32%,除羽化后1 d外,饥饿组含水量均高于羽化后同一时间取食个体;饥饿组可溶性糖、糖原、总脂和可溶性蛋白质的含量分别在6.60~11.21,0.35~10.81,18.28~30.42和12.77~33.44μg/mg鲜重之间,均低于羽化后同一时间取食个体(分别为7.53~11.21,3.66~10.81,27.53~33.63和21.54~34.43μg/mg鲜重)。饥饿3 d恢复取食后1 d,鲜重、干重、含水量和糖原含量均增加,而可溶性糖、总脂和可溶性蛋白质的含量均降低。相关分析表明,饥饿组可溶性糖与糖原、总脂或者可溶性蛋白质的含量以及可溶性蛋白质与糖原或者总脂的含量存在正相关关系。【结论】饥饿胁迫下麦长管蚜的代谢变化与其糖原、总脂和可溶性蛋白质含量降低有密切关系,通过能量物质的综合利用来适应短期饥饿胁迫。     

Effects of Feeding a Histidine-excess Diet and Subsequent Starvation on Liver and Muscle Glycogen,and on Serum Glucose

The effects of feeding with a histidine-excess diet and subsequent starvation on liver and muscle glycogen, and on serum glucose were investigated in young and adult rats.

Feeding with a histidine-excess diet resulted in the accumulation of liver glycogen in both young and adult rats. The hepatic glycogen continued to decrease during starvation, and the liver became almost totally depleted of glycogen after starvation for 48 hr. Glycogen in the liver of young rats starved for 24 hr after previous feeding with a histidine-excess diet was significantly higher than that of young rats starved for 24 hr after previous feeding with a basal diet.

Muscle glycogen after feeding and subsequent starvation was not affected by the types of diets fed previously, muscle glycogen during starvation showing a slight decrease in young rats and a slight increase in adult rats.

Feeding with a histidine-excess diet caused a significant decrease of serum glucose in young rats, but not in adult rats. Serum glucose in young rats was markedly reduced by starvation after previous feeding with a basal diet, but not after previous feeding with a histidine-excess diet. In adult rats, there were no changes in serum glucose between rats starved after feeding with either a basal diet or a histidine-excess diet, and serum glucose was decreased slightly by starvation after feeding with the test diets.

The overall results indicate that the maintenance of serum glucose in young rate even during starvation after previous feeding with a histidine-excess diet might be partially concerned with the export of glucose from the accumulated glycogen in the liver due to the diet.     

Effects of the parasite Probopyrus ringueleti (Isopoda) on glucose, glycogen and lipid concentration in starved Palaemonetes argentinus (Decapoda)

Effects of the branchial ectoparasite isopod Probopyrus ringueleti on the utilization of glucose, glycogen and total lipids on starved shrimp Palaemonetes argentinus were evaluated, as well as the isopod responses to host starvation. Shrimp were maintained for 12 d under laboratory conditions. Parasitized and unparasitized shrimp were starved for 15 d, and glucose, glycogen and total lipid concentrations were determined at 0, 24, 72, 168 and 360 h of starvation. During starvation, control animals (unparasitized) preferentially metabolized lipids and preserved their carbohydrate reserves. Parasitized shrimp had lower lipid concentrations than unparasitized shrimp, and preferentially metabolized carbohydrates. Bopyrids displayed a similar response, with glycogen depleted at the beginning of the starvation period followed by subsequent reestablishment. Our results demonstrated that bopyrids affect host energy allocation. The lower initial lipid concentration of parasitized shrimp suggested that the host is disadvantaged from both food deprivation and isopod nutritional demands. A possible dependency of P. ringueleti on the mechanisms that control host metabolic processes was also suggested.     

The influence of sialoadenectomy, thymectomy and starvation on liver glycogen in the rat

Hepatic glycogen was assayed in young and adult rats subjected to sialoadenectomy and/or thymectomy and starvation. Sialoadenectomy in young, but not in adult rats caused the rats to stop feeding. In young, but not in adult sialoadenectomized and starved rats the glycogen level was notably higher than in unoperated and starved rats, indicating active participation of salivary glucagon in immature animals in hepatic glycogenolysis under conditions of starvation. Simultaneous sialoadenectomy and thymectomy caused glycogen depletion in the liver of young rats in spite of the absence of the salivary glands. Acceleration of glycogenolysis in these rats was not due to thymectomy, being probably a result of excessive secretion of adrenal catecholamines.     

Brain-midgut short neuropeptide F mechanism that inhibits digestive activity of the American cockroach, Periplaneta americana upon starvation

Immunohistochemical reactivity against short neuropeptide F (sNPF) was observed in the brain-corpus cardiacum and midgut paraneurons of the American cockroach, Periplaneta americana. Four weeks of starvation increased the number of sNPF-ir cells in the midgut epithelium but the refeeding decreased the number in 3h. Dramatic rises in sNPF contents in the midgut epithelium and hemolymph of roaches starved for 4 weeks were confirmed by ELISA. Starvation for 4 weeks reduced α-amylase, protease and lipase activities in the midgut of P. americana but refeeding restored these to high levels. Co-incubation of dissected midgut with sNPF at physiological concentrations inhibited α-amylase, protease and lipase activities. sNPF injection into the hemocoel led to a decrease in α-amylase, protease and lipase activities, whereas PBS injection had no effects. The injection of d-(+)-trehalose and l-proline into the hemocoel of decapitated adult male cockroaches that had been starved for 4 weeks had no effect on these digestive enzymes. However, injection into the hemocoel of head-intact starved cockroaches stimulated digestive activity. Injection of d-(+)-trehalose and l-proline into the lumen of decapitated cockroaches that had been starved for 4 weeks increased enzymes activities and suppressed sNPF in the midgut. Our data indicate that sNPF from the midgut paraneurons suppresses α-amylase, protease and lipase activities during starvation. Injection of d-(+)-trehalose/l-proline into the hemocoel of head-intact starved cockroach decreased the hemolymph sNPF content, which suggests that sNPF could be one of the brain factors, demonstrating brain-midgut interplay in the regulation of digestive activities and possibly nutrition-associated behavioral modifications.     

Effects of long-term starvation on body weight and body composition of juvenile channel catfish, Ictalurus punctatus, with special emphasis on amino acid and fatty acid changes

Triplicate groups of 30 channel catfish Ictalurus punctatus (initial weight: 76.13 ± 0.78 g) were stocked in indoor flow‐through fiberglass tanks and starved for 80 days. Body weight, morphometric parameters, body composition, amino acid and fatty acid changes in muscle and liver tissues were investigated to determine the effect of long‐term starvation on body weight and body composition of juvenile channel catfish. During the starvation period, body weight, condition factor (CF), viscerosomatic index (VSI), hepatosomatic index (HSI) and intraperitoneal fat ratio (IPR) declined (P < 0.05). In the whole body, both protein and lipid decreased while changes in the amount of fat were relatively rapid. Hepatic lipid and carbohydrate contents declined as starvation progressed, but crude protein and moisture contents increased (P < 0.05). In contrast, muscle crude protein showed a greater decline than did muscle lipids, and muscle glycogen remained relatively constant. During the 80‐day starvation period the ratio of total essential amino acids (EAA) to total non‐essential amino acids (NEAA) in muscle and liver (P < 0.05) increased. In muscle tissue, total mono‐unsaturated fatty acids (MUFA) and n‐6 fatty acids decreased, but total saturated fatty acids (SFA) and n‐3 fatty acids, as well as the ratio of n‐3 to n‐6 fatty acids increased (P < 0.05). However, in the liver, starvation resulted in the relative increase of total MUFA and reduction in n‐3 fatty acid contents as well as the ratio of n‐3 to n‐6 fatty acids (P < 0.05). Based on these observations, lipids and glycogen can be considered as more important sources of catabolizable energy in liver, whereas protein might be preferentially mobilized in muscle; lipids played a more important role as energy reserves on a relative basis in the whole body. Channel catfish preferentially utilized NEAA to EAA as an energy substrate and preferentially reserved EAA during starvation. Mobilization of fatty acids showed more variation in the muscle and liver during starvation.     

Influence of molting and starvation on the synthesis of proteolytic enzymes in the midgut gland of the white shrimp Penaeus vannamei

We investigated the effect of starvation as a stimulant of the digestive system on digestive proteinase activities in the white shrimp Penaeus vannamei. The starved organisms were sampled periodically according to the molting stage and compared with a continuously fed group. Molting stage was included as an independent variable. Most analyzed variables, except for trypsin, were more affected by starvation than by molting, indicating that starvation is a stimulant that masks the effect of molting and showing that food or alimentary stress is more conspicuous than physiological ones. We found that starvation is a stimulant that surpasses the effect of molting, and because it affects the activity of digestive proteinases, studies of starving organisms in combination with tools of molecular biology, can be a helpful working model in the understanding of mechanisms of regulation of digestive enzyme activity. In the starved organisms, trypsin and chymotrypsin activities were similar, suggesting dependence of one to the other. Changes in proteolytic activities and the number of protein bands in electrophoresis showed evidence of synthesis regulation in the midgut gland of white shrimp.     

Digestive cells in the midgut of Triatoma vitticeps (Stal, 1859) in different starvation periods

Triatoma vitticeps (Stal, 1859) is a hematophagous Hemiptera that, although being considered wild, can be found in households, being a potential Chagas’ disease vector. This work describes the histology and ultrastructure of the midgut of T. vitticeps under different starvation periods. Fifteen adults of both sexes starved for 3, 7, 20 and 25 days were studied. In general, digestive cells had apical microvilli, basal plasma membrane infoldings and central nucleus. The perimicrovillar membrane was found in all insects examined. Digestive cells of anterior midgut had lipid droplets, glycogen granules, developed basal labyrinth associated with mitochondria suggesting their role in nutrient storage and in fluid and ion transport. The cells of median and posterior regions of the midgut were rich in rough endoplasmic reticulum, lysosomes, vesicles and granules with different electron-densities. Moreover, cells of the posterior portion of the midgut had hemozoyn granules and mitochondria in the apical cytoplasm close to microvilli, suggesting their role in blood digestion and active nutrient absorption. The midgut of T. vitticeps showed differences in digestive cells associated with the time after feeding, and the increase of vesicles amount in long starvation periods, which suggests enzyme storage, which is readily used after a blood meal.     

Compensatory Growth in Juveniles of Freshwater Redclaw Crayfish Cherax quadricarinatus Reared at Three Different Temperatures: Hyperphagia and Food Efficiency as Primary Mechanisms

Feeding restriction, as a trigger for compensatory growth, might be considered an alternative viable strategy for minimizing waste as well as production costs. The study assessed whether juvenile redclaw crayfish Cherax quadricarinatus (initial weight 0.99 ±0.03 g) was able to compensate for feeding restriction at different temperatures (23±1, 27±1 and 31±1°C). Hyperphagia, food utilization efficiency, energetic reserves, and hepatopancreas structure were analyzed. Three temperatures and two feeding regimes (DF-daily fed throughout the experiment and CF- 4 days food deprivation followed by 4 days of feeding, intermittently) were tested. The restriction period was from day 1 to 45, and the recovery period was from day 45 to 90. The previously restricted crayfish held at 23, 27, and 31 ± 1°C displayed complete body weight catch-up through compensatory growth following the restriction period with depressed growth. The mechanisms that might explain this response were higher feed intake (hyperphagia), and increased food utilization efficiency. Hepatopancreatic lipids were used as a metabolic fuel and hepatosomatic index was reduced in the previously restricted crayfish, but recovery at the same level of unrestricted crayfish occurred after the shift to daily feeding. The highest temperature affected adversely growth, feed intake, food efficiency, and metabolism of crayfish, whereas the lowest temperature and feeding restriction induced a more efficient growth of the crayfish.     

An evaluation of purification methods for baculoviruses

In Biomphalaria glabrata parasitized by Schistosoma mansoni there was an increase in relative weight of the digestive gland-gonad complex and a decrease in glycogen in that complex and in the remainder of the carcass by day 25. Glycogen levels further decreased close to zero and remained at this low level for the duration of the experiment. Relative weight of the digestive gland-gonad reached a peak at day 30 and decreased toward normal by day 40. Galactogen levels in the albumen gland, although decreased slightly, were not significantly lower than in normal snails. In starved snails, glycogen and galactogen decreased significantly below normal at day 21 and remained at a low level until the experiment ended. This study raises the possibility that starvation of the host by the parasite may play a significant role in the pathology observed in this infection.     

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.     

Roles of fat body trophocytes,mycetocytes and urocytes in the American cockroach,Periplaneta americana under starvation conditions: An ultrastructural study

In insects, trophocytes (adipocytes) are major cells of a storage organ, the fat body, from which stored glycogen and lipids are mobilized under starvation. However, cockroaches have 2 additional types of cell in the fat body: mycetocytes harboring an endosymbiont, Blattabacterium cuenoti, and urocytes depositing uric acid in urate vacuoles. These cells have not been investigated in terms of their roles under starvation conditions. To gain insight into the roles of trophocytes, mycetocytes and urocytes in cockroaches, structural changes were first investigated in the cells associated with starvation in the American cockroach, Periplaneta americana, by light and electron microscopy. The area of lipid droplets in trophocytes, the endosymbiont population and mitotic activity in mycetocytes, and the area of urate vacuoles in urocytes were analyzed in association with survival rates of the starved cockroaches. After 2 weeks of starvation, trophocytes lost glycogen rosettes and their area of lipid droplets decreased, but almost all cockroaches survived this period. However, further starvation did not reduce the area, but the survival rates dropped rapidly and all cockroaches died in 7 weeks. Endosymbionts were not affected in terms of population size and mitotic activity, even if the cockroaches were dying. The area of urate vacuoles rapidly decreased in a week of starvation and did not recover upon further starvation. These results indicate that starved cockroaches mobilize glycogen and lipids stored in trophocytes to survive for 2 weeks and then die after the exhaustion of nutrients in these cells. Endosymbionts are not digested for the recycling of nutrients, but uric acid is reused under starvation.     

Digestive enzyme profiles reveal digestive capacity and potential energy sources in fed and starved spiny lobster (Jasus edwardsii) phyllosoma larvae

The impact of starvation on the digestive enzyme (protease, trypsin, lipase and amylase) activities of Stage I and IV Jasus edwardsii phyllosoma larvae was used to identify the nutrients metabolised or conserved during food deprivation, highlighting the most critical energy reserves. Protease activities increased significantly in both Stages I and IV phyllosoma, suggesting that protein catabolism provided energy during food deprivation. Lipase activity decreased significantly in starved Stages I and IV larvae indicating that lipid may be spared for fuelling later developmental moults. The use of protein, while sparing lipid, may provide immediate energy but not at the expense of long-term lipid energy stores which are known to be important during their lengthy larval phase. The preferential use of protein during short-term periods of starvation suggests that particular attention must be given to providing sufficient protein in artificial diets at all times. Amylase activity in starved Stage I larvae was lower than in fed animals, suggesting that the starved animals are not gaining sufficient carbohydrate. However, amylase activity was similar in fed and starved Stage IV larvae, possibly due to the catabolism of accumulated glycogen stores that were not sufficiently developed in Stage I animals.     

Salivary digestive enzymes of the wheat bug, Eurygaster integriceps (Insecta: Hemiptera: Scutelleridae)

The digestive enzymes from salivary gland complexes (SGC) of Eurygaster integriceps, and their response to starvation and feeding were studied. Moreover, digestive amylases were partially purified and characterized by ammonium sulfate precipitation and gel filtration chromatography. The SGC are composed of two sections, the principal glands and accessory glands. The principal glands are further divided into the anterior lobes and posterior lobes. The SGC main enzyme was α-amylase, which hydrolyzed starch better than glycogen. The other carbohydrases were also present in the SGC complexes. Enzymatic activities toward mannose (α/β-mannosidases) were little in comparison to activities against glucose (α/β-glucosidases) and galactose (α/β-galactosidases), the latter being the greatest. Acid phosphatase showed higher activity than alkaline phosphatase. There was no measurable activity for lipase and aminopeptidase. Proteolytic activity was detected against general and specific protease substrates. Activities of all enzymes were increased in response to feeding in comparison to starved insects, revealing their induction and secretion in response to feeding pulse. The SGC amylases eluted in four major peaks and post-electrophoretic detection of the α-amylases demonstrated the existence of at least five isoamylases in the SGC. The physiological implication of these findings in pre-oral digestion of E. integriceps is discussed.     

Increased expression of ATG genes during nonfeeding periods in the tick Haemaphysalis longicornis

Ticks are long-lived hematophagous arthropods and have tolerance to starvation. They can survive without food during the host-seeking period for several months to years. To understand how ticks obtain energy over a long period of non-feeding (starvation), we focused on autophagy, a crucial proteolysis system via the lysosomes for various cellular processes that is induced during starvation in eukaryotes. In the present study, EST databases for several organs of the tick Haemaphysalis longicornis led to the identification of HlATG3, HlATG4 and HlATG8, homologues of 3 autophagy-related (ATG) genes, ATG3, ATG4 and ATG8/LC3/GABARAP, respectively, which are essential for the Atg8 conjugation system in model animals. Real-time PCR results revealed that the expression of HlATG3, HlATG4 and HlATG8 in the tick showed higher levels during the non-feeding period than the feeding period, suggesting that the Atg8 conjugation system is at work in unfed ticks. Notably, their expression levels were higher in the midgut, a digestive organ, of unfed than fed adults. Histological analysis demonstrated that lipids and glycogen accumulated within the epithelial cells of the midgut in unfed ticks, implying that the midgut of unfed ticks serves as storage of those components as nutrients during non-feeding. Furthermore, autophagic organelles were found in the midgut undifferentiated cells of unfed ticks. The starved condition appears to be associated with the increased expression of HlATG genes in the midgut of unfed ticks. Tick autophagy might help compensate for the loss of nutrients derived from host blood components during the non-feeding period.     

Cathepsin B from the white shrimp Litopenaeus vannamei: cDNA sequence analysis, tissues-specific expression and biological activity

Cathepsin B is a cystein proteinase scarcely studied in crustaceans. Its function has not been clearly described in shrimp species belonging to the sub-order Dendrobranchiata, which includes the white shrimp Litopenaeus vannamei and other species from the Penaeidae family. Studies on vertebrates suggest that these lysosomal enzymes intracellularly hydrolize protein, as other cystein proteinases. However, the expression of the gene encoding the shrimp cathepsin B in the midgut gland was affected by starvation in a similar way as other digestive proteinases which extracellularly hydrolyze food protein. In this study the white shrimp L. vannamei cathepsin B (LvCathB) cDNA was sequenced, and characterized. Its gene expression was evaluated in various shrimp tissues, and changes in the mRNA amounts were compared with those observed on other digestive proteinases from the midgut gland during starvation. By using qRT-PCR it was found that LvCathB is expressed in most shrimp tissues except in pleopods and eye stalk. Changes on LvCathB mRNA during starvation suggest that the enzyme participates during intracellular protein hydrolysis but also, after food ingestion, it participates in hydrolyzing food proteins extracellularly as confirmed by the high activity levels we found in the gastric juice and midgut gland of the white shrimp.