No abstract

African mole-rats (Bathyergidae, Rodentia) contain several social, cooperatively breeding species with low extrinsic mortality and unusually high longevity. All social bathyergids live in multigenerational families where reproduction is skewed towards a few breeding individuals. Most of their offspring remain as reproductively inactive “helpers” in their natal families, often for several years. This “reproductive subdivision” of mole-rat societies might be of interest for ageing research, as in at least one social bathyergid (Ansell's mole-rats Fukomys anselli), breeders have been shown to age significantly slower than non-breeders. These animals thus provide excellent conditions for studying the epigenetics of senescence by comparing divergent longevities within the same genotypes without the inescapable short-comings of inter-species comparisons. It has been claimed that many if not all social mole-rat species may have evolved similar ageing patterns, too. However, this remains unclear on account of the scarcity of reliable datasets on the subject. We therefore analyzed a 20-year breeding record of Giant mole-rats Fukomys mechowii, another social bathyergid species. We found that breeders indeed lived significantly longer than helpers (ca. 1.5–2.2fold depending on the sex), irrespective of social rank or other potentially confounding factors. Considering the phylogenetic positions of F. mechowii and F. anselli and unpublished data on a third Fukomys-species (F. damarensis) showing essentially the same pattern, it seems probable that the reversal of the classic trade-off between somatic maintenance and sexual reproduction is characteristic of the whole genus and hence of the vast majority of social mole-rats.

The genus Cryptomys contains a number of social, subterranean rodents that are widely distributed throughout subSaharan Africa. Specimens of Cryptomys from 23 localities in south-west Zambia were karyotyped using a standard staining protocol. A minimum of five metaphases per specimen was scored for 2n and the fundamental number (NF) was determined in females. Nine new karyotypes, which may represent several new species, were identified: (1) 2n = 42, NF = 78 (Dongo, Southern Province); (2) 2n = 44, NF = 76 (Salujinga, North-western Province); (3) 2n = 45, NF = 78 (Lochinvar, Southern Province); (4) 2n = 52, NF = 86 (Chinyingi, North-western Province); (5) 2n = 54, NF = 78 (Monze, Southern Province); (6) 2n = 56, NF = 76 (Watopa, North-western Province); (7) 2n = 58, NF = 80 (Livingstone, Southern Province); (8) 2n = 58, NF = 86 (Senanga, Western Province); (9) 2n = 60, NF = 82 (Kataba, Western Province; type locality of C. damarensis micklemi). Contrary to previous reports, the specimens from Kataba and Senanga on the left bank of the Zambezi do not correspond to C. damarensis and should be considered a separate species: C. micklemi (as confirmed by molecular analyses; Ingram, Burda & Honeycutt, 2004). According to the karyotype, C. damarensis occurs only on the right bank of the Zambezi River in the Western Province. In contrast to the high karyotypic variability on the right bank of the Kafue River, it was found that C. anselli (2n = 68) is widely distributed throughout the Central province on the left bank of the Kafue River. The resulting pattern of occurrence of the different karyotypes correlates well with the extant river system configuration that separates most karyotypes. We hypothesize that geomorphological changes and in particular river system dynamics in recent geological times have played an important role in the chromosomal diversification and may have provided opportunities for speciation to occur.

The upregulation of Dll4-Notch signaling components was found in a subset of GBM samples and was associated with some angiogenic and clinical parameters. These findings highlight this signaling pathway as a potential therapeutic target for patients with GBM who show an activation of Dll4-Notch signaling.

Most research on mechanisms of aging is being conducted in a very limited number of classical model species, i.e., laboratory mouse (Mus musculus), rat (Rattus norvegicus domestica), the common fruit fly (Drosophila melanogaster) and roundworm (Caenorhabditis elegans). The obvious advantages of using these models are access to resources such as strains with known genetic properties, high-quality genomic and transcriptomic sequencing data, versatile experimental manipulation capabilities including well-established genome editing tools, as well as extensive experience in husbandry. However, this approach may introduce interpretation biases due to the specific characteristics of the investigated species, which may lead to inappropriate, or even false, generalization. For example, it is still unclear to what extent knowledge of aging mechanisms gained in short-lived model organisms is transferable to long-lived species such as humans. In addition, other specific adaptations favoring a long and healthy life from the immense evolutionary toolbox may be entirely missed. In this review, we summarize the specific characteristics of emerging animal models that have attracted the attention of gerontologists, we provide an overview of the available data and resources related to these models, and we summarize important insights gained from them in recent years. The models presented include short-lived ones such as killifish (Nothobranchius furzeri), long-lived ones such as primates (Callithrix jacchus, Cebus imitator, Macaca mulatta), bathyergid mole-rats (Heterocephalus glaber, Fukomys spp.), bats (Myotis spp.), birds, olms (Proteus anguinus), turtles, greenland sharks, bivalves (Arctica islandica), and potentially non-aging ones such as Hydra and Planaria.