Resveratrol, a natural phytoalexin found in grapes and red wine, increases longevity in the short-lived invertebrates Caenorhabditis elegans and Drosophila and exerts a variety of biological effects in vertebrates, including protection from ischemia and neurotoxicity. Its effects on vertebrate lifespan were not yet known. The relatively long lifespan of mice, which live at least 2.5 years, is a hurdle for life-long pharmacological trials. Here, the authors used the short-lived seasonal fish Nothobranchius furzeri with a maximum recorded lifespan of 13 weeks in captivity. Short lifespan in this species is not the result of spontaneous or targeted genetic mutations, but a natural trait correlated with the necessity to breed in an ephemeral habitat and tied with accelerated development and expression of ageing biomarkers at a cellular level. Resveratrol was added to the food starting in early adulthood and caused a dose-dependent increase of median and maximum lifespan. In addition, resveratrol delays the age-dependent decay of locomotor activity and cognitive performances and reduces the expression of neurofibrillary degeneration in the brain. These results demonstrate that food supplementation with resveratrol prolongs lifespan and retards the expression of age-dependent traits in a short-lived vertebrate.

The killifish Nothobranchius furzeri is the shortest-lived vertebrate that can be bred in the laboratory. Its rapid growth, early sexual maturation, fast aging, and arrested embryonic development (diapause) make it an attractive model organism in biomedical research. Here, we report a draft sequence of its genome that allowed us to uncover an intra-species Y chromosome polymorphism representing-in real time-different stages of sex chromosome formation that display features of early mammalian XY evolution "in action." Our data suggest that gdf6Y, encoding a TGF-β family growth factor, is the master sex-determining gene in N. furzeri. Moreover, we observed genomic clustering of aging-related genes, identified genes under positive selection, and revealed significant similarities of gene expression profiles between diapause and aging, particularly for genes controlling cell cycle and translation. The annotated genome sequence is provided as an online resource (http://www.nothobranchius.info/NFINgb).

African annual fishes from the genus Nothobranchius are small teleosts that inhabit temporary water bodies subject to annual desiccation due to the alternation of the monsoon seasons. Given their unique biology, these fish have emerged as a model taxon in several biological disciplines. Their increasing popularity stems from the extremely short lifespan that is the result of their specific life-history adaptations and is retained under laboratory conditions. Nothobranchius furzeri, the most popular laboratory species, is the vertebrate species with the shortest lifespan recorded in captivity. In the laboratory, adults of different Nothobranchius species and populations live between 3 and 18 months and, notably, there is a negative correlation between the captive lifespan of a species and the aridity of their habitat. Their short lifespan is coupled to rapid age-dependent functional decline and expression of cellular and molecular changes comparable to those observed in other vertebrates, including humans. The recent development of transgenesis in this species makes it possible to insert specific constructs into their genome, and the establishment of transgenic lines is facilitated by their very rapid generation time, which can be as short as 1 month. This makes Nothobranchius species particularly suited for investigating biological and molecular aspects of ageing and ageing-associated dysfunctions. At the same time, they also represent a unique model taxon to investigate the evolution of life-history adaptations and their genetic architecture. We review their natural history, including phylogenetic relationships, distribution in relation to habitat conditions and natural selection for differential longevity, population structure and demography, and life cycle with emphasis on diapause that may occur at three stages during embryonic development. We further critically evaluate their use as a laboratory model for understanding the evolution of a rapid ageing rate and its consequences for other life-history traits, for cellular, molecular and integrative traits associated with the ageing process, high incidence of neoplasias, their utility for genome-wide gene-expression studies, and as a model for quantitative genetics. We summarize recent achievements in fostering Nothobranchius species as a widely applicable model system, including an annotated transcriptome, successful transgenesis, and existence of viable inbred lines. We compare the conditions they experience in the wild and in captivity and suggest that they are an ideal taxon to investigate natural genetic variation in a laboratory setting. We conclude that Nothobranchius species -and N. furzeri in particular -could become a unique model taxon that bridges interests in ecological and biomedical research. We hope that a conceptual and methodological integration of these two branches of biology will provide important new insights.

SummaryAging research in vertebrates is hampered by the lack of shortlived models. Annual fishes of the genus Nothobranchius live in East African seasonal ponds. Their life expectancy in the wild is limited by the duration of the wet season and their lifespan in captivity is also short. Nothobranchius are popular aquarium fishes and many different species are kept as captive strains, providing rich material for comparative studies. The present paper aims at reviving the interest in these fishes by reporting that: (1) Nothobranchius can be cultured, and their eggs stored dry at room temperature for months or years, offering inexpensive methods of embryo storage; (2) Nothobranchius show accelerated growth and expression of aging biomarkers at the level of histology and behaviour; (3) the species Nothobranchius furzeri has a maximum lifespan of only 3 months and offers the possibility to perform investigations thus far unthinkable in a vertebrate, such as drug screening with life-long pharmacological treatments and experimental evolution; (4) when the lifespan of different species is compared, a general correlation is found between wet season duration in their natural habitat and longevity in captivity; and (5) vertebrate aging-related genes, such as p66Shc and MTP , can be easily isolated in Nothobranchius by homology cloning. These fishes can become excellent models for aging studies. They can be employed to test the effects of experimental manipulation on aging at a pace comparable with that of Drosophila and to probe the effects of natural selection on the evolution of aging-related genes.

BackgroundA laboratory inbred strain of the annual fish Nothobranchius furzeri shows exceptionally short life expectancy and accelerated expression of age markers. In this study, we analyze new wild-derived lines of this short-lived species.Methodology/Principal FindingsWe characterized captive survival and age-related traits in F1 and F2 offspring of wild-caught N. furzeri. Wild-derived N. furzeri lines showed expression of lipofuscin and neurodegeneration at age 21 weeks. Median lifespan in the laboratory varied from to 20 to 23 weeks and maximum lifespan from 25 to 32 weeks. These data demonstrate that rapid age-dependent decline and short lifespan are natural characteristics of this species. The N. furzeri distribution range overlaps with gradients in altitude and aridity. Fish from more arid habitats are expected to experience a shorter survival window in the wild. We tested whether captive lines stemming from semi-arid and sub-humid habitats differ in longevity and expression of age-related traits. We detected a clear difference in age-dependent cognitive decline and a slight difference in lifespan (16% for median, 15% for maximum lifespan) between these lines. Finally, we observed shorter lifespan and accelerated expression of age-related markers in the inbred laboratory strain compared to these wild-derived lines.Conclusions/SignificanceOwing to large differences in aging phenotypes in different lines, N. furzeri could represent a model system for studying the genetic control of life-history traits in natural populations.

The brains of teleost fish show extensive adult neurogenesis and neuronal regeneration. The patterns of gene regulation during fish brain aging are unknown. The short-lived teleost fish Nothobranchius furzeri shows markers of brain aging including reduced learning performances, gliosis, and reduced adult neurogenesis. We used RNA-seq to quantify genome-wide transcript regulation and sampled five different time points to characterize whole-genome transcript regulation during brain aging of N. furzeri. Comparison with human datasets revealed conserved up-regulation of ribosome, lysosome, and complement activation and conserved down-regulation of synapse, mitochondrion, proteasome, and spliceosome. Down-regulated genes differ in their temporal profiles: neurogenesis and extracellular matrix genes showed rapid decay, synaptic and axonal genes a progressive decay. A substantial proportion of differentially expressed genes (∼40%) showed inversion of their temporal profiles in the last time point: spliceosome and proteasome showed initial down-regulation and stress-response genes initial up-regulation. Extensive regulation was detected for chromatin remodelers of the DNMT and CBX families as well as members of the polycomb complex and was mirrored by an up-regulation of the H3K27me3 epigenetic mark. Network analysis showed extensive coregulation of cell cycle/DNA synthesis genes with the uncharacterized zinc-finger protein ZNF367 as central hub. In situ hybridization showed that ZNF367 is expressed in neuronal stem cell niches of both embryonic zebrafish and adult N. furzeri. Other genes down-regulated with age, not previously associated with adult neurogenesis and with similar patterns of expression are AGR2, DNMT3A, KRCP, MEX3A, SCML4, and CBX1. CBX7, on the other hand, was up-regulated with age.

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Brain-derived neurotrophic factor (BDNF) partially promotes the survival of axotomized retinal ganglion cells (RGCs). In analogy with in vitro experiments (Koh et al., 1995;Samdami et al., 1996), we tested whether neuroprotection by BDNF is limited by adverse effects as a consequence of excessive free radical formation. First, we investigated whether BDNF and the free radical scavenger N-tert-butyl-(2-sulfophenyl)-nitrone (S-PBN) cooperate in protecting RGCs from axotomy-induced death. Although systemic S-PBN treatment alone did not influence RGC survival after axotomy, it potentiated the neuroprotective effects of BDNF significantly. Single BDNF treatment rescued 27% of the RGCs, which otherwise would have died 14 d after optic nerve transection, whereas a combined treatment of BDNF and S-PBN improved this rescue rate up to 68%. We then investigated whether the adverse effects of BDNF could be ascribed to activation of nitric oxide synthase (NOS). We found colocalization of NOS and the BDNF receptor TrkB in the retina. NADPH-diaphorase reactivity, a reliable marker for NOS in the rat retina, increased after chronic BDNF treatment in vivo. Systemic application of the NOS-inhibitor N--nitro-L-argininemethylester (L-NAME) potentiated the neuroprotective action of BDNF (55% rescue rate). We conclude that activation of NOS is a pathological consequence of BDNF application, which reduces its neuroprotective potential. The observation that this adverse effect can be antagonized by systemic application of free radical scavengers could be of relevance for clinical applications of neurotrophins in human neurodegenerative diseases.