No abstract

Despite considerable progress in recent years, many questions regarding fish larval nutrition remain largely unanswered, and several research avenues remain open. A holistic understanding of the supply line of nutrients is important for developing diets for use in larval culture and for the adaptation of rearing conditions that meet the larval requirements for the optimal presentation of food organisms and/or microdiets. The aim of the present review is to revise the state of the art and to pinpoint the gaps in knowledge regarding larval nutritional requirements, the nutritional value of live feeds and challenges and opportunities in the development of formulated larval diets.

Genetic reference populations, particularly the BXD recombinant inbred (BXD RI) strains derived from C57BL/6J and DBA/2J mice, are a valuable resource for the discovery of the bio-molecular substrates and genetic drivers responsible for trait variation and covariation. This approach can be profitably applied in the analysis of susceptibility and mechanisms of drug and alcohol use disorders for which many predisposing behaviors may predict the occurrence and manifestation of increased preference for these substances. Many of these traits are modeled by common mouse behavioral assays, facilitating the detection of patterns and sources of genetic coregulation of predisposing phenotypes and substance consumption. Members of the Tennessee Mouse Genome Consortium (TMGC) have obtained phenotype data from over 250 measures related to multiple behavioral assays across several batteries: response to, and withdrawal from cocaine, 3,4-methylenedioxymethamphetamine; “ecstasy” (MDMA), morphine and alcohol; novelty seeking; behavioral despair and related neurological phenomena; pain sensitivity; stress sensitivity; anxiety; hyperactivity and sleep/wake cycles. All traits have been measured in both sexes in approximately 70 strains of the recently expanded panel of BXD RI strains. Sex differences and heritability estimates were obtained for each trait, and a comparison of early (N = 32) and recent (N = 37) BXD RI lines was performed. Primary data are publicly available for heritability, sex difference and genetic analyses using the MouseTrack database, and are also available in GeneNetwork.org for quantitative trait locus (QTL) detection and genetic analysis of gene expression. Together with the results of related studies, these data form a public resource for integrative systems genetic analysis of neurobehavioral traits.

Ethanol exposure during development is particularly deleterious to cerebellar Purkinje cells and granule cells, but the mechanism(s) underlying this sensitivity and the variables which affect it remain unknown. One important variable that has not been fully investigated, is the timing of the ethanol exposure. Ethanol exposure during the brain growth spurt causes a differential loss of Purkinje cells across the 10 lobules of the vermal cerebellum. However, whether or not changing the timing of the ethanol exposure during the brain growth spurt alters the extent and location of the loss of Purkinje cells within the cerebellar vermis has not been investigated. Moreover, the loss of cerebellar granule cells has been shown to parallel the loss of Purkinje cells, leading to the conclusion that the loss of granule cells occurred as a function of the loss of their targets, the Purkinje cells. The purpose of this study was to address both issues. Male rat pups were exposed to ethanol, via an artificial-rearing method, during one of the following 2-day time periods: postnatal days (PD) 4-5, 5-6, 6-7, 7-8, 8-9, 9-10, or 12-13. Gastrostomy control (GC) and suckle control (SC) groups also were included. All pups were sacrificed on PD21. The number of Purkinje cell nuclear profiles from three vermal sections were counted in all groups, while the number of granule cell nuclear profiles in the ten lobules was estimated from pups in selected groups. No loss of Purkinje cells was observed in pups exposed to ethanol on PD7-8 or at any of the later exposure times. Additionally, among the three exposure groups in which significant Purkinje cell loss was observed (PD4-5, PD5-6 and PD6-7), seven lobules exhibited significant differences particularly between the PD4-5 and PD6-7 groups. The group with the greatest loss of Purkinje cells (PD4-5) also was the group with the greatest loss of granule cells. A significant loss of granule cells did not occur without a corresponding loss of Purkinje cells. The loss of both the Purkinje and granule cells was affected by the timing of the ethanol exposure, and that the extent and the location of Purkinje cell loss were extremely sensitive to the effects of the timing of the ethanol exposure.

Vitamin E is a generic term for a group of lipid‐soluble molecules, the tocopherols and tocotrienols, which have a function in the protection of organisms against lipid oxidation and which also may have other, more specific biological functions. In fish, as in other vertebrates, α‐tocopherol (TOH) is preferentially retained in the body compared to the other tocopherols, probably because of the presence of a tocopherol transfer protein (TTP) in the liver which binds the tocopherols with different affinities and returns them to the circulation. Tocopherols that bind weakly to TTP are to a greater extent excreted in the bile. α‐TOH interacts with other nutrients, and the requirement therefore varies with the dietary composition. High levels of polyunsaturated fatty acids, and low levels of vitamin C, selenium and astaxanthin increase the requirement. This is attributed to the dynamic nature of both lipid oxidation and the antioxidant defence, where oxidized vitamin E is recycled by other antioxidants. The interactions also determine the display of vitamin E deficiency signs, immune responses and effects on flesh quality. Within the mammalian nutrition research community, there is a controversy as to whether vitamin E is primarily an antioxidant or a specific modulator of cell signalling through regulation of enzyme activities and gene expression and some of the hypotheses are presented in this review.