Crustaceans are cultured extensively around the world in intensive farming systems. High‐performance formulated feeds have been developed for crustacean aquaculture, which are often supplemented with a number of natural and synthetic carotenoid sources. Studies over a number of years have consistently shown that dietary carotenoid supplementation is beneficial for crustacean aquaculture across a range of commercially relevant parameters. Most obvious is the effect on pigmentation, where carotenoid inclusion levels in feeds and duration of feeding diets with carotenoids have been optimised across many species to improve product colour, and subsequently quality and price. However, beneficial effects of carotenoid inclusion have increasingly been demonstrated on other parameters. This review updates the recent progress in our understanding of dietary carotenoid utilisation and storage, and the combined effects of diet, genetics and environment on crustacean pigmentation. In addition, the range of other physiological benefits this class of molecules brings to these animals is summarised. These include improvements in survival, growth, reproductive capacity, disease resistance and stress resistance.

Syntaxin 7 is a mammalian target soluble N-ethylmaleimide-sensitive factor attachment protein receptor (SNARE) involved in membrane transport between late endosomes and lysosomes. The aim of the present study was to use immunoaffinity techniques to identify proteins that interact with Syntaxin 7. We reasoned that this would be facilitated by the use of cells producing high levels of Syntaxin 7. Screening of a large number of tissues and cell lines revealed that Syntaxin 7 is expressed at very high levels in B16 melanoma cells. Moreover, the expression of Syntaxin 7 increased in these cells as they underwent melanogenesis. From a large scale Syntaxin 7 immunoprecipitation, we have identified six polypeptides using a combination of electrospray mass spectrometry and immunoblotting. These polypeptides corresponded to Syntaxin 7, Syntaxin 6, mouse Vps10p tail interactor 1b (mVti1b), ␣-synaptosome-associated protein (SNAP), vesicle-associated membrane protein (VAMP)8, VAMP7, and the protein phosphatase 1M regulatory subunit. We also observed partial colocalization between Syntaxin 6 and Syntaxin 7, between Syntaxin 6 and mVti1b, but not between Syntaxin 6 and the early endosomal t-SNARE Syntaxin 13. Based on these and data reported previously, we propose that Syntaxin 7/mVti1b/Syntaxin 6 may form discrete SNARE complexes with either VAMP7 or VAMP8 to regulate fusion events within the late endosomal pathway and that these events may play a critical role in melanogenesis.In eukaryotic cells, proteins are transported between intracellular organelles by a series of membrane transport steps. The ability of discrete organelles to fuse in a highly specific way is central to all membrane-trafficking events and relies on a series of molecular events. One event is the formation of a protein complex between sets of molecules found within the transport vesicle (v-SNAREs) 1 and the target membrane (t-SNAREs). Much of the work that has led to the formulation of this hypothesis has been performed in the mammalian synapse (1). Here the R-or v-SNARE, VAMP2, forms a complex with two Q-or t-SNARE proteins, Syntaxin 1a and SNAP25. This ternary complex consists of a four-␣-helical bundle containing one helix from both Syntaxin 1a and VAMP2 with the remaining two helices being contributed by SNAP25 (2). SNARE complexes that regulate traffic to the cell surface in both mammalian and yeast cells contain three distinct proteins, whereas most intracellular SNARE complexes appear to be comprised of four separate proteins: one v-SNARE and three t-SNAREs (3, 4). For example, in Saccharomyces cerevisiae endoplasmic reticulum to Golgi transport is regulated by the Sed5p⅐Bos1p⅐Sec22p⅐Bet1p complex, whereas vacuolar transport is regulated by a complex comprising Vam3p⅐Vam7p⅐Vti1p⅐Nyv1p (3). The Syntaxin isoform, or t-SNARE heavy chain (3), associated with each complex appears to be highly specific to a particular vesicle transport step, whereas the light chain t-SNAREs associate with multiple complexes. Vti1p, for example, interacts with Syntaxin ho...

Dominant mutations in the gene encoding the mRNA splicing factor PRPF31 cause retinitis pigmentosa, a hereditary form of retinal degeneration. Most of these mutations are characterized by DNA changes that lead to premature termination codons. We investigated 6 different PRPF31 mutations, represented by single-base substitutions or microdeletions, in cell lines derived from 9 patients with dominant retinitis pigmentosa. Five of these mutations lead to premature termination codons, and 1 leads to the skipping of exon 2. Allele-specific measurement of PRPF31 transcripts revealed a strong reduction in the expression of mutant alleles. As a consequence, total PRPF31 protein abundance was decreased, and no truncated proteins were detected. Subnuclear localization of the full-length PRPF31 that was present remained unaffected. Blocking nonsense-mediated mRNA decay significantly restored the amount of mutant PRPF31 mRNA but did not restore the synthesis of mutant proteins, even in conjunction with inhibitors of protein degradation pathways. Our results indicate that most PRPF31 mutations ultimately result in null alleles through the activation of surveillance mechanisms that inactivate mutant mRNA and, possibly, proteins. Furthermore, these data provide compelling evidence that the pathogenic effect of PRPF31 mutations is likely due to haploinsufficiency rather than to gain of function.

Carotenoids are commonly used by disparate metazoans to produce external coloration, often in direct association with specific proteins. In one such example, crustacyanin (CRCN) and the carotenoid astaxanthin combine to form a multimeric protein complex that is critical for the array of external shell colors in clawed lobsters. Through a combined biochemical, molecular genetic, and bioinformatic survey of the distribution of CRCN across the animal kingdom, we have found that CRCNs are restricted to, but widespread among, malacostracan crustaceans. These crustacean-specific genes separate into two distinct clades within the lipocalin protein superfamily. We show that CRCN differentially localizes to colored shell territories and the underlying epithelium in panulirid lobsters. Given the paramount importance of CRCN in crustacean shell colors and patterns and the critical role these play in survival, reproduction, and communication, we submit that the origin of the CRCN gene family early in the evolution of malacostracan crustaceans significantly contributed to the success of this group of arthropods.

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SUMMARYExposure of prawns to dark-or light-coloured substrates is known to trigger a strong colour adaptation response through expansion or contraction of the colouration structures in the prawn hypodermis. Despite the difference in colour triggered by this adaptive response, total levels of the predominant carotenoid pigment, astaxanthin, are not modified, suggesting that another mechanism is regulating this phenomenon. Astaxanthin binds to a specific protein called crustacyanin (CRCN), and it is the interaction between the quantities of each of these compounds that produces the diverse range of colours seen in crustacean shells. In this study, we investigated the protein changes and genetic regulatory processes that occur in prawn hypodermal tissues during adaptation to black or white substrates. The amount of free astaxanthin was higher in animals adapted to dark substrate compared with those adapted to light substrate, and this difference was matched by a strong elevation of CRCN protein. However, there was no difference in the expression of CRCN genes either across the moult cycle or in response to background substrate colour. These results indicate that exposure to a dark-coloured substrate causes an accumulation of CRCN protein, bound with free astaxanthin, in the prawn hypodermis without modification of CRCN gene expression. On light-coloured substrates, levels of CRCN protein in the hypodermis are reduced, but the carotenoid is retained, undispersed in the hypodermal tissue, in an esterified form. Therefore, the abundance of CRCN protein affects the distribution of pigment in prawn hypodermal tissues, and is a crucial regulator of the colour adaptation response in prawns.

The regulation of gene expression by nutrients is an important mechanism governing energy storage and growth in most animals, including fish.Understanding the timing and intensity of these responses is the first critical step in defining the molecular effects of different dietary nutrient sources. In this study, changes in key metabolic regulators of nutritional pathways were investigated in barramundi fed a meal of a diet formulated with 500, 150 and 110 g kg -1 dry matter of protein, lipid and carbohydrate, respectively. Plasma glucose levels showed a postprandial peak two hours after feeding, and had returned to basal levels within four hours. Significant activation of genes that regulate glycolytic and lipogenic pathways immediately post feeding were observed, in combination with down-regulation of genes that control gluconeogenesis and activation of the Akt-mTOR pathway. Strong correlations were identified between a number of different metabolic genes, and the coordinated co-regulation of these genes may underlie the ability of this fish to effectively regulate circulating plasma glucose levels. Overall, post-prandial responses in barramundi were observed to be extremely rapid compared with other fish species, and there was no prolonged hyperglycaemia with a diet low in carbohydrates. These data clearly demonstrate, for the first time, the molecular changes that control intermediary metabolism in barramundi in response to feeding a single meal of a diet formulated within optimal specifications for this species.

22This study examined the effect of including different dietary proportions of starch, protein 23 and lipid, in diets balanced for digestible energy, on the utilisation efficiencies of dietary energy by 24 barramundi (Lates calcarifer). Each diet was fed at one of three ration levels (satiety, 80% of initial 25 satiety and 60% of initial satiety) for a 42-day period. Fish performance measures (weight gain, feed 26 intake, and feed conversion ratio) were all affected by dietary energy source. The efficiency of energy 27 utilisation was significantly reduced in fish fed the starch diet relative to the other diets, but there 28 were no significant effects between the other macronutrients. This reduction in the efficiency of Barramundi are an obligate carnivorous fish species that is the basis of a significant 40 aquaculture industry in Southeast Asia and Australia (1). The development of high-nutrient density 41 formulated extruded feeds has been underpinned by the development of both a series of factorial 42 bioenergetic nutritional models and foundation empirical studies (1, 2, 3, 4, 5). These nutritional 43 models have so far relied on the assumption that the dietary digestible energy (DE) source is 44 irrelevant; that is that the dietary DE derived from protein, lipid and starch is utilised with equal 45 efficiency, subject to key nutrients (e.g. protein) being provided at/or above minimum critical ratios to 46 energy supply (4, 5, 6, 7, 8, 9, 10). 47 Each of the different macronutrients (starch, protein and lipid) supplies energy by distinct 48 metabolic pathways. In aquatic animals it is recognised that there are different levels of efficiency in 49 the utilisation of each these macronutrients for energy (11, 12). It is now recognised that this 50 difference requires an amendment of the digestible nutritional values of each macronutrient to those 51 of metabolisable nutritional values and/or net energy nutritional values (9, 12, 13, 14). Recent work 52 by Schrama et al. (14) examined the utilisation of both starch and lipid for growth by the omnivorous respectively. These observations clearly indicated that this fish species used lipid as an energy source 57 for growth more efficiently. However, the third key macronutrient, protein, was not considered in this 58 study. In that same study, Schrama et al. (14) in reviewing the literature identified that there was a 59 wide variability (0.31 to 0.82) in the kgDE of different studies. It was suggested that the three primary 60 reasons for this variability were: different dietary macronutrient compositions; trophic level of the fish 61 species; and the composition of the growth. In addition, there is increasing evidence that the roles of 62 gluconeogenesis, glycolysis and -oxidation play substantially different relative roles in energy 63 provision in fish compared to other vertebrates (11, 14, 15, 16, 17). 64 The objective of this study was to determine the partial efficiencies of utilisation of each of 65 the d...