The role of larval nutrition in pre-imaginal biasing of caste in the primitively eusocial wasp Ropalidia marginata (Hymenoptera: Vespidae)

1. When freshly eclosed females of the primitively eusocial wasp Ropalidia marginata (Lep.) are isolated, only about 50% of them build nests and lay eggs thereby suggesting a pre-imaginal biasing of caste. 2. Wasps that lay eggs take a very variable amount of time after eclosion to start doing so. 3. Females eclosing from nests where larvae are fed at a relatively higher rate are more likely to become egg-layers and are likely to take less time after eclosion to begin to lay eggs. 4. Thus, both forms of pre-imaginal biasing of caste, namely, differences in egg laying capacity and differences in the time taken to attain reproductive maturity, appear to be influenced by larval nutrition.

Studies on Larval Nutrition in The Pearl Oyster Pinctada Pucata (Gould)

The present study has yielded a great deal of information on nutrition of pearl oyster larvae. T he formulae presented may be used effectively and with advantage in improving the larval rearing system with specific reference to nutritional aspects. It is also hoped that this is the first comprehensive study on pearl oyster larval nutrition would stimulate further detailed investigations on many of the other finer aspects of tropical bivalve larval nutrition.

Molecular cloning and functional analysis of cathepsin B in nutrient metabolism during larval development in Meretrix meretrix

Seed rearing is an important part in large scale clam culture industry. Since the nutritional history affects early development in bivalve, the condition of larval nutrition plays a key role in successful seed rearing. So far, the molecular mechanism of nutrient uptake in bivalve larvae is unclear. As one of the important proteolytic enzymes, cathepsin B of several organisms has been reported to be involved in digestion. We intended to analyze whether cathepsin B is involved in larval nutrient metabolism in the economic bivalve, clam Meretrix meretrix. The full length of M. meretrix cathepsin B (MmeCB) cDNA was cloned, which is 1647 bp with an open reading frame of 1014 bp. The deduced amino acid sequence encoded a preproenzyme of 337 residues with Cys-114, His-282 and Asn-302 composing cathepsin B activity center. The temporal and spatial expressions of MmeCB mRNA were examined from trochophore to post larva stages by whole mount in situ hybridization. In trochophore stage, no detectable signal was found. In the later three stages, MmeCB mRNA was detected in the digestive gland, suggesting a possible role of MmeCB in digestion. Moreover, MmeCB mRNA was also observed in the epidermal cells in D-veligers. Cathepsin B specific inhibitor (CA074 methyl ester) was applied to block the activity of cathepsin B in unfed larvae. The average shell lengths of treated larvae were smaller than that in control groups. The results of mRNA epidermal distribution and inhibitor treatment in D-veligers indicated that MmeCB may be also associated with other pathway of nutrient metabolism in larval epidermis. The overall results in this paper revealed that MmeCB might play a role in larval nutrient metabolism. (C) 2008 Elsevier B.V. All rights reserved.

Effect of larval food amount on ovariole development in queens of Trigona spinipes (Hymenoptera, Apinae)

Caste determination in Trigona spinipes Fabricius (Hymenoptera, Apidae, Meliponini) is trophogenic. Larvae that eat about 360 mu l of food become queens, while those who consume 36 mu l develop into workers. We studied the effect of larval nutrition on the number and length of ovarioles and on ovarian development in fifth instar larvae, white eyed, pink eyed and black-eyed pupae as well as newly emerged adults. All larvae have four ovarioles per ovary, while in queen pupae this number ranged from 8 to 15. Cyst formation, the cell death and other characteristics of ovary morphogenesis were the same regardless of the quantity of food consumed. These results are discussed in relation to caste differentiation in other bees.

Estudo da dispersão larval radial pós-alimentar em Chrysomya megacephala (Fabricius) (Diptera, Calliphoridae)

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Dispersão larval radial pós-alimentar em Lucilia cuprina (Diptera, Calliphoridae): profundidade, peso e distância de enterramento para pupação

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Efeito do tipo de substrato para pupação na dispersão larval pós-alimentar de Chrysomya albiceps (Diptera, Calliphoridae)

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Processos auto-organizados: efeitos de substâncias químicas que agem no sistema nervoso sobre o desenvolvimento e padrão de dispersão larval pós-alimentar de dípteros (Calliphoridae e Muscidae)

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Postfeeding radial dispersal in larvae of Chrysomya albiceps (Diptera : Calliphoridae): implications for forensic entomology

Blowflies utilize discrete and ephemeral breeding sites for larval nutrition. After the exhaustion of food, larvae begin dispersing in search of sites to pupate or additional food sources, a process referred as postfeeding larval dispersal. Some of the most important aspects of this process were investigated in the blowfly Chrysomya albiceps, employing a circular arena to allow radial dispersion of larvae from the center. The results showed a positive correlation between burial depth and distance, and a negative correlation between distance and pupal weight. These results can be used in forensic entomology for the postmortem interval estimation of human corpses in medico-criminal investigations. (c) 2004 Elsevier B.V.. All rights reserved.

Influence of photoperiod on body weight and depth of burrowing in larvae of Chrysomya megacephala (Fabricius) (Diptera, Calliphoridae) and implications for forensic entomology

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Optimización del cultivo de diatomeas bentónicas para el cultivo de post-larvas de abalón ("Haliotis tuberculata coccinea" Reeve, 1846)

[EN] Diatom cell quantity and their biochemical composition vary among species and are greatly affected by harvest stage or culture conditions. Biometric parameters, growth, attachment capacity and variations in biochemical composition of four species of benthic diatoms (Amphora sp., Navicula incerta, Nitzschia sp. and Proschkinia sp.) were studied. For biochemical analysis the diatoms were harvested at different stages, in log and stationary phase of growth. The culture conditions were identical for all the experiments, benthic diatoms were cultured during 7 days in F/2 medium at 28.5 ± 1.4 ºC, at different original inoculating densities (50000, 100000, and 250000 cell mL-1), under continuous light of 5403 ± 649 Lux provided by cool white fluorescent lighting. The cultures were neither aerated nor agitated. These results show that the specific density of 10000 cell mL-1 was the best for weekly production: Proschkinia sp. reached the highest cell density of 5.81 x 106 cells mL-1 and Amphora sp. had the highest cell attachment capacity with 12000 cell mm-2, in stationary phase of growth. Protein and lipid content were higher in log phase than in stationary phase for the four diatoms. Amphora sp. in log phase of growth had the highest lipid content of 9.74% dry weight (DW). Polyunsaturated fatty acid (PUFA) content ranged from 23.25% to 38.62% of the total fatty acids (TFA), and the four diatoms tested were richer in n-3 PUFA than in n-6 PUFA. All the diatoms had significant quantities of 20:5n-3 (EPA) ranging between 12.69% and 17.68% of TFA. Benthic diatoms play an important and critical role in abalone culture as they are the principal food source of abalone post-larvae. Therefore, it is necessary to improve diatom quantity and quality to optimize post-larval nutrition and the consistency of production, resulting in an increase in growth and survival of abalones.

Both apolipoprotein E and A-I genes are present in a nonmammalian vertebrate and are highly expressed during embryonic development

Apolipoprotein E (apoE) is associated with several classes of plasma lipoproteins and mediates uptake of lipoproteins through its ability to interact with specific cell surface receptors. Besides its role in cardiovascular diseases, accumulating evidence has suggested that apoE could play a role in neurodegenerative diseases, such as Alzheimer disease. In vertebrates, apoA-I is the major protein of high-density lipoprotein. ApoA-I may play an important role in regulating the cholesterol content of peripheral tissues through the reverse cholesterol transport pathway. We have isolated cDNA clones that code for apoE and apoA-I from a zebrafish embryo library. Analysis of the deduced amino acid sequences showed the presence of a region enriched in basic amino acids in zebrafish apoE similar to the lipoprotein receptor-binding region of human apoE. We demonstrated by whole-mount in situ hybridization that apoE and apoA-I genes are highly expressed in the yolk syncytial layer, an extraembryonic structure implicated in embryonic and larval nutrition. ApoE transcripts were also observed in the deep cell layer during blastula stage, in numerous ectodermal derivatives after gastrulation, and after 3 days of development in a limited number of cells both in brain and in the eyes. Our data indicate that apoE can be found in a nonmammalian vertebrate and that the duplication events, from which apoE and apoA-I genes arose, occurred before the divergence of the tetrapod and teleost ancestors. Zebrafish can be used as a simple and useful model for studying the role of apolipoproteins in embryonic and larval nutrition and of apoE in brain morphogenesis and regeneration.

Stage-Specific Plasticity in Ovary Size Is Regulated by Insulin/Insulin-Like Growth Factor and Ecdysone Signaling in Drosophila

Animals from flies to humans adjust their development in response to environmental conditions through a series of developmental checkpoints, which alter the sensitivity of organs to environmental perturbation. Despite their importance, we know little about the molecular mechanisms through which this change in sensitivity occurs. Here we identify two phases of sensitivity to larval nutrition that contribute to plasticity in ovariole number, an important determinant of fecundity, in Drosophila melanogaster. These two phases of sensitivity are separated by the developmental checkpoint called "critical weight"; poor nutrition has greater effects on ovariole number in larvae before critical weight than after. We find that this switch in sensitivity results from distinct developmental processes. In precritical weight larvae, poor nutrition delays the onset of terminal filament cell differentiation, the starting point for ovariole development, and strongly suppresses the rate of terminal filament addition and the rate of increase in ovary volume. Conversely, in postcritical weight larvae, poor nutrition affects only the rate of increase in ovary volume. Our results further indicate that two hormonal pathways, the insulin/insulin-like growth factor and the ecdysone-signaling pathways, modulate the timing and rates of all three developmental processes. The change in sensitivity in the ovary results from changes in the relative contribution of each pathway to the rates of terminal filament addition and increase in ovary volume before and after critical weight. Our work deepens our understanding of how hormones act to modify the sensitivity of organs to environmental conditions, thereby affecting their plasticity.