Prolonged Periods Of Starvation Research Articles

Octopamine integrates the status of internal energy supply into the formation of food-related memories

The brain regulates food intake in response to internal energy demands and food availability. However, can internal energy storage influence the type of memory that is formed? We show that the duration of starvation determines whether Drosophila melanogaster forms appetitive short-term or longer-lasting intermediate memories. The internal glycogen storage in the muscles and adipose tissue influences how intensely sucrose-associated information is stored. Insulin-like signaling in octopaminergic reward neurons integrates internal energy storage into memory formation. Octopamine, in turn, suppresses the formation of long-term memory. Octopamine is not required for short-term memory because octopamine-deficient mutants can form appetitive short-term memory for sucrose and to other nutrients depending on the internal energy status. The reduced positive reinforcing effect of sucrose at high internal glycogen levels, combined with the increased stability of food-related memories due to prolonged periods of starvation, could lead to increased food intake.

Octopamine integrates the status of internal energy supply into the formation of food-related memories.

The brain regulates food intake in response to internal energy demands and food availability. However, can internal energy storage influence the type of memory that is formed? We show that the duration of starvation determines whether Drosophila melanogaster forms appetitive short-term or longer-lasting intermediate memories. The internal glycogen storage in the muscles and adipose tissue influences how intensely sucrose-associated information is stored. Insulin-like signaling in octopaminergic reward neurons integrates internal energy storage into memory formation. Octopamine, in turn, suppresses the formation of long-term memory. Octopamine is not required for short-term memory because octopamine-deficient mutants can form appetitive short-term memory for sucrose and to other nutrients depending on the internal energy status. The reduced positive reinforcing effect of sucrose at high internal glycogen levels, combined with the increased stability of food-related memories due to prolonged periods of starvation, could lead to increased food intake.

A Qualitative Systematic Review of Risk Factors for Refeeding Syndrome

ObjectivesRefeeding syndrome (RFS) is characterized by potentially fatal electrolyte shifts after resumption of feeding following a period of prolonged starvation. The lack of a standardized definition has made the study of RFS difficult. Early identification of patients at risk of RFS may prevent life-threatening complications and improve outcomes. However, the sensitivity of reported risk factors depends on the definition used, and many have never been validated. This study was designed to identify risks for RFS that have been identified in prior studies. It is preparatory for a larger analysis to better identify sensitive and specific risk factors for RFS.MethodsThis is a qualitative systematic review of observational studies following Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. Studies reporting the incidence of RFS were included. Risk factors were extracted whether identified in review or as a measured exposure. Risk factors were considered distinct if they were not described similarly (e.g., BMI, admit BMI, nadir BMI, BMI < 16, BMI < 18.5 were each treated as distinct).ResultsRisk factors were reviewed or studied in 43 of 49 studies that met inclusion criteria. A total of 129 distinct risk factor definitions were extracted. Of these, only 29 used definitions similar enough to other studies to be considered the same by the reviewers (range 2 to 8 studies per risk factor; median 3 studies). NICE guidelines were mentioned in 3 studies. No other published guidelines were found.ConclusionsCreating a risk profile for patients may help tailor interventions to prevent RFS. There was a large heterogeneous number of risk factors and numerous discrepancies in description of risk factors among the studies. The low incidence of inclusion of poor intake (i.e., less than 100%) in the identified studies was of interest. Next steps will include prospective validation of identified risks, as well as AI analyses to identify and validate other risk factors and biomarkers, with the goal to develop sensitive and specific risk assessments, and effective preventive and treatment protocols.Funding SourcesNone.

Molecular detection of blood meal source up to three months since the last meal: Experimental starvation resistance in triatomines

The identification of Blood Meal Source (BMS) in hematophagous vectors contributes to a better understanding of the ecology of hemoparasite transmission. Those insects can endure long periods without feeding, waiting for a favorable setting. Although this represents an important behavior observed in those groups, such as triatomines, little is known about how time can affect BMS detection, especially considering extended periods. To comprehend to which extent this behavioral phenomenon can impact molecular detection, we submitted two groups of Rhodnius robustus to increasing periods of starvation under experimental conditions. It was possible to recover the BMS until the 12th week of the starvation process. Nymphs were more resistant to prolonged periods of starvation (up to more than 189 days) than adults (maximum of 137 days), with no significant difference between their weights after being fed. The study brought new insights to the understanding of Trypanosoma cruzi transmission by R. robustus in the nature, with a temporal perspective.

Quantitative Parameters of the Body Composition Influencing Host Seeking Behavior of Ixodes ricinus Adults.

Ixodes ricinus, a hematophagous arthropod species with great medical importance in the northern hemisphere, is characterized by an ability to survive prolonged periods of starvation, a wide host spectrum, and high vector competence. The aim of the present study was to determine the quantitative parameters of questing I. ricinus ticks collected in eastern Poland during the spring peak of their activity. The study consisted in the determination of quantitative parameters characterizing I. ricinus females and males, i.e., fresh body mass, reduced body mass, lipid-free body mass, water mass, and lipid mass and calculation of the lipid index. A statistically significant difference was observed between the mean values of the lipid index in females collected during the first and last ten days of May, which indicates the progressive utilization of reserve materials in the activity period. Higher activity of I. ricinus female ticks was observed during the last ten days of May despite the less favorable weather conditions, indicating their strong determination in host-seeking behaviors accompanying a decline in the lipid content and the use of the “now or never” strategy.

Надлишкова вага та ожиріння: чи є взаємозв’язок з харчовою поведінкою?

Obesity is a non-infectious epidemic of the XXI century. The social significance of the problem of obesity is determined by the threat of disability of young patients and the reduction of overall life expectancy due to the frequent development of severe diseases. Eating behaviour disorders are the leading factors in the development of overweight and obesity. The purpose of the work was to determine the relationship between overweight and obesity with eating behaviour, taking into account the gender and age characteristics of patients. Material and methods. A survey of 272 people (136 men and 136 women) was conducted. The examined patients were divided into two clinical groups: I group included 90 people (45 women and 45 men) with excess weight (BMI = 27.7±1.31 kg / m2); Group II had 92 people (46 women and 46 men) with obesity of 1 degree (BMI = 31.74±1.03 kg / m2). Evaluation of eating disorders was carried out using the DEBQ questionnaire (Netherlands) adapted to the purpose of the study. Results and discussion. Eating behaviour disorders are one of the leading factors in the development of overweight and obesity: in overweight patients a healthy type of eating behaviour was recorded 4.86 times less often than in normal weight (D = 13.56, p = 2.35 e-14 &lt;0.05), and in obese patients it was 7.14 times less often than in normal weight individuals (D = 21.04, p = 2.2e-16 &lt;0.05). Overweight and obesity are most often associated with a restrictive type of eating behaviour: in overweight people they were met 4 times more often (D = 0.16, p-value = 4.637e-06 &lt;0.05), and in obese patients disorders of the restrictive type of eating behaviour were 4.24 times more often compared to the control group (D = 0.15, p-value = 6.148e-07 &lt;0.05). The type of eating behaviour in all clinical groups, except for body mass index, was influenced by gender and age of the subjects. Thus, in overweight men after the age of 45 a healthy type of eating behaviour occurred 8.09 times more often than in men under the age of 45 (D = 0.11, p-value = 0.03 &lt;0.05) and in overweight women (D = 0.11, p-value = 0.03 &lt;0.05). The relationship between the type of eating behaviour and gender and age characteristics of patients was found and confirmed by correlation analysis in all clinical groups. Conclusions. Healthy eating behaviour disorders are one of the leading factors in the development of overweight and obesity. Correction of eating disorders in obese people must be carried out taking into account the gender and age characteristics of the patient, to obtain positive results for a shorter course of treatment. Medical advice for women and young people, taking into account the prevalence of restrictive eating behaviour disorders, should be aimed at combating strict diets and periods of prolonged starvation; men and people over 45, taking into account the prevalence of external eating behaviour disorders, should follow a balanced diet. The duration of corrective treatment in obese women should be increased through psychotherapy

Comparison of the body mass of Dermacentor reticulatus ticks from two ecologically varied habitats located in a close vicinity.

Dermacentor reticulatus as hematophagous arthropod has a great veterinary and epidemiological significance in Europe as a vector and reservoir of numerous pathogens including bacteria, rickettsia, viruses and protozoa. Because of biological and ecological traits, i.e. ability to survive prolonged periods of starvation, ecological plasticity, adaptability and resistance to fluctuating and adverse environmental conditions D. reticulatus ticks are an important parts of enzootic cycles, thus have been studied intensively since last years. Genetic studies of ticks collected in Poland suggest existence of the overlapping zone between two European populations of this species. The aim of this study was to compare the body mass (as reduced body mass) of D. reticulatus females and males collected in two plots, representing different ecological characteristics, located in close vicinity, placed in Lublin province (eastern Poland). The results indicate that the reduced body mass values of D. reticulatus adults collected in diverse microhabitats did significantly vary. The cause of this phenomenon is ambiguous, so it need to be elucidated in further studies.

Silencing of ATG6 and ATG8 promotes increased levels of triacylglycerol (TAG) in the fat body during prolonged starvation periods in the Chagas disease vector Rhodnius prolixus

Rhodnius prolixus is an obligatorily hematophagous insect known as an important vector of Chagas disease. Autophagy is a conserved cellular mechanism that acts in response to nutrient starvation, where components of the cytoplasm are sequestered by a double membrane organelle, named autophagosome, which is targeted to fuse with the lysosome for degradation. Lipophagy is the process of lipid degradation by selective autophagy, where autophagosomes sequester lipid droplets and degrade triacylglycerol (TAG) generating free fatty acids for β-oxidation. Here, two essential genes of the autophagic pathway, Atg6/Beclin1 (RpAtg6) and Atg8/LC3 (RpAtg8), were silenced and the storage of lipids during starvation in Rhodnius prolixus was monitored. We found that RNAi knockdown of both RpAtg6 and RpAtg8 resulted in higher levels of TAG in the fat body and the flight muscle, 24 days after the blood meal, as well as a larger average diameter of the lipid droplets in the fat body, as seen by Nile Red staining under the confocal fluorescence microscope. Silenced starved insects had lower survival rates when compared to control insects. Accordingly, when examined during the starvation period for monitored activity, silenced insects had lower spontaneous locomotor activity and lower forced flight rates. Furthermore, we found that some genes involved in lipid metabolism had their expression levels altered in silenced insects, such as the Brummer lipase (down regulated) and the adipokinetic hormone receptor (up regulated), suggesting that, as previously observed in mammalian models, the autophagy and neutral lipolysis machineries are interconnected at the transcriptional level. Altogether, our data indicate that autophagy in the fat body is important to allow insects to mobilize energy from lipid stores.

‘STARVING’ STUDENTS: GASTROPOETICS OF THE ‘LOWER’ BAROQUE IN THE POETRY OF WANDERING DYAKS

The author analyzes wandering dyaks as a specific group of 18th-century Ukrainian city and town intellectuals. During vacations and religious holidays, these young people went to high clergy and secular houses. They sang congratulatory songs about Christmas or Easter and delivered orations – poetic humorous speeches – abo school life and pupils’ wretchedness. For their performance, the wandering dyaks were rewarded, mostly with food. There was a special order from the administration of Kyiv-Mohyla Academy to release poor students for food begging with the obligation to return before the beginning of the school year. Therefore, such poems usually ended with a request for a reward.&#x0D; Gastronomic poetics is one of the key tools of the «grassroots» baroque that appeared thanks to the intersection of the intellectual urban and folk rural cultures. This phenomenon became the basis for Ivan Kotlyarevsky’s «Eneida», a step towards new-time Ukrainian literature.&#x0D; The texts analyzed in the article were first found in manuscript songbooks of 18th and early 19th century, both in Naddnipryanshchyna and Western Ukraine. It is noticeable that even after the end of the baroque epoch these songs were not forgotten, they were still performed, and ethnographers fixed them in various versions.&#x0D; In contrast to the of «high» baroque, marked by the occurrence of metaphoricity and abstractness, one of the main characteristics of wandering dyaks’ poems is the emphasis on materiality, especially food. According to this, it is worth using gastrocriticism to interpret orations and travesties.&#x0D; Gastronomic markers in the festive burlesque function as a series of oppositions: daily and ceremonial food; proper and improper; moderate and excessive; bestowed and stolen; banned and allowed; spiritual and carnal. Four aspects are investigated in the article. First of all, the self-image of ever-hungry students is closely reviewed. School life for common citizen had a clear association with poverty, which pointes the prominent role of malnutrition and forced fasting in poems of wandering dyaks. Secondly, the appearing of gastronomic utopias is proved as a reaction to a prolonged period of starvation. One more aspect is the conviction of excessive feeding. The last but not the least is the motive of giving, feasting and donating food in the poems of wandering dyaks.&#x0D; The poetry of wandering dyaks consists of the element of folk culture, on the one hand, and the literary imagery, on the other. For the intellectual of the 18th-century nutrition, along with the usual meaning, reflects the unity of bodily and spiritual parts of human nature. In the baroque culture, the widespread metaphor is eating as a spiritual act, and the cognition is perceived as the saturation of the inner world. Nutrition is considered in two semantic terms: firstly, food as a sign of physicality and, potentially, sinfulness and seduction; secondly, food as the embodiment of eternal life, the celebration of vitality. The «high» baroque culture transmits the first vision. Instead, the «lower» culture is characterized by the second idea, which explains the emergence of gastronomic fantasies in the poems of wandering dyaks.

Et tu, brother? Kinship and increased nutrition lower the incidence of cannibalism in male bulb mites

The killing of conspecifics returns indirect benefits when killers eliminate competitors for resources, and direct benefits when cannibals obtain nutrients directly after killing. Cannibals risk pathogen infection and both killers and cannibals risk reducing their inclusive fitness when killing kin. When competing with kin over food during a prolonged period of starvation, we surmise that this cost–benefit ratio will stay almost constant for killers, as their benefits are indirect so that they direct killing away from kin (unless in extremis), but that this ratio will reduce over time for cannibals, as their benefits are direct, such that they will start consuming kin when food stressed. We tested this hypothesis using the male-dimorphic bulb mite Rhizoglyphus robini in which males are armed ‘fighters’ that can kill and cannibalize or unarmed ‘scramblers’. In four-fighter groups that were either starved or fed for 2 weeks, and that comprised either kin (brothers) or nonkin (at most cousins), we assessed the number of dead and cannibalized fighters. The cumulative number of dead and cannibalized fighters was higher under starved than under fed conditions, and increased over time, rejecting our hypothesis. Instead, we found that fewer kin than nonkin were cannibalized, but fighters discriminated to a much lesser extent between kin and nonkin when killing. Hypothetically, cannibalism of kin incurs a greater risk of infection by pathogens to which cannibals are genetically susceptible. Our results highlight the importance of distinguishing killing from cannibalism, as they can have contrasting effects on the demography of populations.

Effect of starvation and re-feeding on the digestive system of Penaeus japonicus Spence Bate, 1888

This study investigated the effects of starvation and refeeding on the histological features of stomach and intestine in Penaeus japonicus Spence Bate, 1888. Five treatment groups of P. japonicus were initially starved for 0, 5, 10, 15 and 25 days (designated as S0, S5, S10, S15 and S25, respectively) and subsequently fed for 15 days. The effect on digestive system was evaluated using epithelial cell height in stomach and intestine as the assessment criteria and significant decrease in epithelial cell height was considered as damage due to starvation. With prolonged starvation period, the structure of stomach and intestine were found compromised. In the 5 days starvation group (S5), the damage of the digestive system was not significant, whereas the damages became significant after 25 days starvation (S25). In the damaged digestive system of shrimp, the boundary disappeared and the cells were found disassembled. The lumen of hepatic tubule in midgut gland enlarged, the number of the R cells decreased, and the cells were found disassembled. After refeeding, the structures in the stomach, intestine and midgut gland recovered, almost similar to the control group except in the 25 days starvation group. Results from the present study provide practical guidelines for feeding pattern during culture of P. japonicus.

DksA Controls the Response of the Lyme Disease Spirochete Borrelia burgdorferi to Starvation.

The pathogenic spirochete Borrelia burgdorferi senses and responds to changes in the environment, including changes in nutrient availability, throughout its enzootic cycle in Ixodes ticks and vertebrate hosts. This study examined the role of DnaK suppressor protein (DksA) in the transcriptional response of B. burgdorferi to starvation. Wild-type and dksA mutant B. burgdorferi strains were subjected to starvation by shifting cultures grown in rich complete medium, Barbour-Stoenner-Kelly II (BSK II) medium, to a defined mammalian tissue culture medium, RPMI 1640, for 6 h under microaerobic conditions (5% CO2, 3% O2). Microarray analyses of wild-type B. burgdorferi revealed that genes encoding flagellar components, ribosomal proteins, and DNA replication machinery were downregulated in response to starvation. DksA mediated transcriptomic responses to starvation in B. burgdorferi, as the dksA-deficient strain differentially expressed only 47 genes in response to starvation compared to the 500 genes differentially expressed in wild-type strains. Consistent with a role for DksA in the starvation response of B. burgdorferi, fewer CFU of dksA mutants were observed after prolonged starvation in RPMI 1640 medium than CFU of wild-type B. burgdorferi spirochetes. Transcriptomic analyses revealed a partial overlap between the DksA regulon and the regulon of RelBbu, the guanosine tetraphosphate and guanosine pentaphosphate [(p)ppGpp] synthetase that controls the stringent response; the DksA regulon also included many plasmid-borne genes. Additionally, the dksA mutant exhibited constitutively elevated (p)ppGpp levels compared to those of the wild-type strain, implying a regulatory relationship between DksA and (p)ppGpp. Together, these data indicate that DksA, along with (p)ppGpp, directs the stringent response to effect B. burgdorferi adaptation to its environment.IMPORTANCE The Lyme disease bacterium Borrelia burgdorferi survives diverse environmental challenges as it cycles between its tick vectors and various vertebrate hosts. B. burgdorferi must withstand prolonged periods of starvation while it resides in unfed Ixodes ticks. In this study, the regulatory protein DksA is shown to play a pivotal role controlling the transcriptional responses of B. burgdorferi to starvation. The results suggest that DksA gene regulatory activity impacts B. burgdorferi metabolism, virulence gene expression, and the ability of this bacterium to complete its natural life cycle.

Lipid droplet biogenesis is spatially coordinated at ER-vacuole contacts under nutritional stress.

Eukaryotic cells store lipids in cytosolic organelles known as lipid droplets (LDs). Lipid droplet bud from the endoplasmic reticulum (ER), and may be harvested by the vacuole for energy during prolonged periods of starvation. How cells spatially coordinate LD production is poorly understood. Here, we demonstrate that yeast ER-vacuole contact sites (NVJs) physically expand in response to metabolic stress, and serve as sites for LD production. NVJ tether Mdm1 demarcates sites of LD budding, and interacts with fatty acyl-CoA synthases at the NVJ periphery. Artificially expanding the NVJ through over-expressing Mdm1 is sufficient to drive NVJ-associated LD production, whereas ablating the NVJ induces defects in fatty acid-to-triglyceride production. Collectively, our data suggest a tight metabolic link between nutritional stress and LD biogenesis that is spatially coordinated at ER-vacuole contact sites.

Bulimia Nervosa/Purging Disorder

Bulimia nervosa was first described in 1979 by British psychiatrist Gerald Russell as a "chronic phase of anorexia nervosa" in which patients overeat and then use compensatory mechanisms, such as self-induced vomiting, laxatives, or prolonged periods of starvation. The characterization of bulimia nervosa continues to evolve with the introduction of the DSM-5 in 2013. In this article, the epidemiology and risk factors of bulimia nervosa are identified and reviewed, along with the medical complications and psychiatric comorbidities. The evaluation of a patient with suspected bulimia nervosa is addressed, with an emphasis on acquiring a complete and thorough history as well as discovering any comorbidities that are present. Management of the patient involves both medical interventions and behavioral counseling in order to address physical, psychological, and social needs. Lastly, a new diagnosis introduced in the DSM-5, purging disorder, is described and discussed.

The Cyanobacterial Ribosomal-Associated Protein LrtA Is Involved in Post-Stress Survival in Synechocystis sp. PCC 6803.

A light-repressed transcript encodes the LrtA protein in cyanobacteria. We show that half-life of lrtA transcript from Synechocystis sp. PCC 6803 is higher in dark-treated cells as compared to light-grown cells, suggesting post-transcriptional control of lrtA expression. The lrtA 5´ untranslated leader region is involved in that darkness-dependent regulation. We also found that Synechocystis sp. PCC 6803 LrtA is a ribosome-associated protein present in both 30S and 70S ribosomal particles. In order to investigate the function of this protein we have constructed a deletion mutant of the lrtA gene. Cells lacking LrtA (∆lrtA) had significantly lower amount of 70S particles and a greater amount of 30S and 50S particles, suggesting a role of LrtA in stabilizing 70S particles. Synechocystis strains with different amounts of LrtA protein: wild-type, ∆lrtA, and LrtAS (overexpressing lrtA) showed no differences in their growth rate under standard laboratory conditions. However, a clear LrtA dose-dependent effect was observed in the presence of the antibiotic tylosin, being the LrtAS strains the most sensitive. Similar results were obtained under hyperosmotic stress caused by sorbitol. Conversely, after prolonged periods of starvation, ∆lrtA strains were delayed in their growth with respect to the wild-type and the LrtAS strains. A positive role of LrtA protein in post-stress survival is proposed.

Genotoxic effects of starvation and dimethoate in haemocytes and midgut gland cells of wolf spider Xerolycosa nemoralis (Lycosidae)

The aim of this study was to assess the genotoxic effects of starvation and dimethoate (organophosphate insecticide) in female and male wolf spiders Xerolycosa nemoralis (Lycosidae) exposed to the stressors under laboratory conditions. DNA damage was measured in haemocytes and midgut gland cells using the comet assay. In response to the two stressing factors, both cell types showed %TDNA, tail length (TL) and OTM values higher in males than in females. Level of DNA damage in haemocytes was greater than in midgut gland cells. In both sexes, the strongest genotoxicity was recorded at single application of dimethoate. After five-time exposure to the pesticide, genotoxic effects of a single dose were sustained in males and reduced to the control level in females. Starvation stress was well tolerated by the females, in which neither cell type was affected by DNA damage. However, in male haemocytes food deprivation induced severe DNA damage, what suggests suppression of the defence potential at prolonged starvation periods.

Understanding of aerobic granulation enhanced by starvation in the perspective of quorum sensing.

Three sequencing batch reactors (M1, M2, and M3) were set up to investigate the influence of different lengths of starvation time (3, 5, and 7h) on aerobic granulation in the perspective of quorum sensing (QS). Autoinducer-2 (AI-2) level was quantified to evaluate the QS ability of aerobic granules. The results indicated that AI-2 level increased steadily during a cycle of sequencing batch reactors, suggesting that starvation was closely related to AI-2 secretion. In the long-term operation, aerobic granules cultivated using a prolonged starvation period had a better integrity and a higher level of cell adhesiveness despite a slower formation speed. With the extension of the starvation period, the total amount of extracellular polymeric substances (EPS) displayed an increasing tendency. EPS with large molecular weight (MW) also reached a higher level using a prolonged starvation period. However, a higher level of AI-2 and cell adhesiveness was observed in M2, which might be related to more stable granules. The results implied that the starvation period could trigger AI-2 secretion and promoted the production of large MW EPS, leading to cell adhesiveness enhancement and granule formation. Therefore, a combination of different starvation periods was proposed in this study in order to improve aerobic granulation.

Carbon-Starvation Induces Cross-Resistance to Thermal, Acid, and Oxidative Stress in Serratia marcescens.

The broad host-range pathogen Serratia marcescens survives in diverse host and non-host environments, often enduring conditions in which the concentration of essential nutrients is growth-limiting. In such environments, carbon and energy source starvation (carbon-starvation) is one of the most common forms of stress encountered by S. marcescens. Related members of the family Enterobacteriaceae are known to undergo substantial changes in gene expression and physiology in response to the specific stress of carbon-starvation, enabling non-spore-forming cells to survive periods of prolonged starvation and exposure to other forms of stress (i.e., starvation-induced cross-resistance). To determine if carbon-starvation also results in elevated levels of cross-resistance in S. marcescens, both log-phase and carbon-starved cultures, depleted of glucose before the onset of high cell-density stationary-phase, were grown in minimal media at either 30 °C or 37 °C and were then challenged for resistance to high temperature (50 °C), low pH (pH 2.8), and oxidative stress (15 mM H2O2). In general, carbon-starved cells exhibited a higher level of resistance to thermal stress, acid stress, and oxidative stress compared to log-phase cells. The extent of carbon-starvation-induced cross-resistance was dependent on incubation temperature and on the particular strain of S. marcescens. In addition, strain- and temperature-dependent variations in long-term starvation survival were also observed. The enhanced stress-resistance of starved S. marcescens cells could be an important factor in their survival and persistence in many non-host environments and within certain host microenvironments where the availability of carbon sources is suboptimal for growth.

Phylogenetic evidence for multiple independent origins of functional kleptoplasty in Sacoglossa (Heterobranchia, Gastropoda)

Sacoglossa is a rather small taxon of marine slugs with about 300 described species, yet it is quite fascinating scientists for decades. This is mainly because of the ability of certain species to incorporate photosynthetically active plastids of their algae prey, a phenomenon known as functional kleptoplasty. With the stolen plastids, these slugs endure weeks (short-term retention) or months (long-term retention) of starvation, though contribution of the plastids to the survival and factors enhancing plastid longevity are unknown. Likewise, contrasting hypotheses on evolution of functional kleptoplasty exist and the phylogenetic relationship of Sacoglossa taxa is still under debate. We analyzed the phylogenetic relationship of 105 sacoglossan species to address the question of the origin of functional kleptoplasty. Based on our phylogenetic analysis and the ancestral character state reconstruction, we conclude that functional short-term retention most likely originated two times and long-term retention at least five times. Previous suggestions that functional long-term kleptoplasty is established with specific plastids are supported by our food analyses in Elysia clarki that finally harbors only plastids of certain algae species over a prolonged starvation period.

Effects of Delayed First Feeding on Larval Growth and Survival of Yesso Scallop (Patinopecten yessoensis)

The time of first feeding is an important factor for establishing successful initial feeding in molluscan hatcheries. The effects of delayed first feeding on larval growth and survival in the larvae of Yesso Scallop Patinopecten yessoensis were investigated in this study. Groups of larvae were fed at early stage of D-shaped larvae or delayed for 24, 48, 72, 96, 120 and 144 h. When first feeding was delayed for less than 72 h, the P. yessoensis larvae grew as rapidly as those non-starved larvae. When delayed first feeding for more than 72 h, the growth rates of larvae were significantly reduced (less than 2 µm day-1), half or less than those of the non-starved group. The survival rates decreased sharply with the prolonged starvation period and the extremely low survival rates were observed in the groups that were delayed first feeding for more than 72 h. The results indicate that the prolonged starvation had a deleterious impact on the larval growth and survival when delayed first feeding for 96 h or more. To avoid mass mortality and obtain adequate growth and survival, food availability within 72 h after early D-shaped larvae is critical important for the successful initial feeding in commercial culture of this species.