We mainly (but not exclusively) draw on research and development work carried out by The WorldFish Center (WorldFish). We review in detail the current state of development of a selection program that has had a main focus on growth rate and body traits. We also present some new, unpublished, information. There is evidence of sustained gains of 10–15% per generation over more than six generations. To date, these gains have not been accompanied by any undesirable correlated response. However, the prospects of altering sexual dimorphism and the shape of the fish appear to be very limited. We also examine the issue of an appropriate environment for selection. Not surprisingly, experimental evidence on genotype by environment interactions suggests that this is more likely to be of importance when the environments in question are markedly dissimilar. We argue that no universal guidelines can be prescribed with regard to the need for more than one selection program to cope with different production environments, but rather, each case should be examined in its own right. Finally, we discuss traits likely to be candidates for inclusion in future, more elaborate, breeding objectives for Nile tilapia (Oreochromis niloticus), comment on selection methods that may be implemented in the future and conclude by stressing the need to maintain an effective population size in selection lines to ensure their sustainability over time.

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SUMMARY Postnatal organogenesis occurs in an immune competent environment and is tightly controlled by interplay between positive and negative regulators. Innate immune cells have beneficial roles in postnatal tissue remodeling, but roles for the adaptive immune system are currently unexplored. Here we show that adaptive immune responses participate in the normal postnatal development of a non-lymphoid epithelial tissue. Since the mammary gland (MG) is the only organ developing predominantly after birth, we utilized it as a powerful system to study adaptive immune regulation of organogenesis. We found that antigen-mediated interactions between mammary antigen-presenting cells and interferon-γ (IFNγ)-producing CD4+ T helper 1 cells participate in MG postnatal organogenesis as negative regulators, locally orchestrating epithelial rearrangement. IFNγ then affects luminal lineage differentiation. This function of adaptive immune responses regulating normal development changes the paradigm for studying players of postnatal organogenesis and provides insights into immune surveillance and cancer transformation.

This study provides an overview of successful genetic improvement programmes for important farmed aquaculture species in Asia, with a focus on lessons and experiences gained as well as challenges remaining. In both fish and prawns (Macrobrachium rosenbergii), conventional selective breeding approaches have resulted in significant improvement in productivity, with genetic gains ranging from 8 to 12% per generation. Selection for high growth has also brought about beneficial changes in fillet weight of fish and edible meat in prawns without detrimental effects on flesh quality attributes and fitness-related traits. Genetically improved animals show remarkable vigour and high adaptation to a range of culture environments/conditions in Asian countries. Despite these successes, however, the conduct and practical implementation of such breeding programmes still present several challenges. These include the expansion of breeding objectives, management of inbreeding in closed-selection populations, controlling the effects of genotype by environment interactions, simultaneous production of large number of fulland half-sib families for species with asynchronous spawning behaviour, maintaining pedigree records, dissemination of the improved strains for widespread production, as well as a reluctance by many to carry out systematically designed genetic improvement for aquatic animal species. There are also challenges with regard to the application of genomic information in genetic enhancement programmes and the development of genetically improved strains in response to climate and environmental changes. In this study, each of these challenges is discussed and solutions are proposed to increase efficiency of future genetic improvement programmes for economically important aquaculture species.