Trade-off between somatic and germline repair in a vertebrate supports the "expensive germ line" hypothesis

The disposable soma theory is a central tenet of the biology of aging where germline immortality comes at the cost of an aging soma [T. B. L. Kirkwood, Nature 270, 301–304 (1977); T. B. L. Kirkwood, Proc. R. Soc. Lond. B Biol. Sci. 205, 531–546 (1979); T. B. L. Kirkwood, S. N. Austad, Nature 408, 233–238 (2000)]. Limited resources and a possible trade-off between the repair and maintenance of the germ cells and growth and maintenance of the soma may explain the deterioration of the soma over time. Here we show that germline removal allows accelerated somatic healing under stress. We tested “the expensive germ line” hypothesis by generating germline-free zebrafish Danio rerio and testing the effect of the presence and absence of the germ line on somatic repair under benign and stressful conditions. We exposed male fish to sublethal low-dose ionizing radiation, a genotoxic stress affecting the soma and the germ line, and tested how fast the soma recovered following partial fin ablation. We found that somatic recovery from ablation occurred substantially faster in irradiated germline-free fish than in the control germline-carrying fish where somatic recovery was stunned. The germ line did show signs of postirradiation recovery in germline-carrying fish in several traits related to offspring number and fitness. These results support the theoretical conjecture that germline maintenance is costly and directly trades off with somatic maintenance

The genetic legacy of the expansion of Bantu-speaking peoples in Africa.

The expansion of people speaking Bantu languages is the most dramatic demographic event in Late Holocene Africa and fundamentally reshaped the linguistic, cultural and biological landscape of the continent1-7. With a comprehensive genomic dataset, including newly generated data of modern-day and ancient DNA from previously unsampled regions in Africa, we contribute insights into this expansion that started 6,000-4,000 years ago in western Africa. We genotyped 1,763 participants, including 1,526 Bantu speakers from 147 populations across 14 African countries, and generated whole-genome sequences from 12 Late Iron Age individuals8. We show that genetic diversity amongst Bantu-speaking populations declines with distance from western Africa, with current-day Zambia and the Democratic Republic of Congo as possible crossroads of interaction. Using spatially explicit methods9 and correlating genetic, linguistic and geographical data, we provide cross-disciplinary support for a serial-founder migration model. We further show that Bantu speakers received significant gene flow from local groups in regions they expanded into. Our genetic dataset provides an exhaustive modern-day African comparative dataset for ancient DNA studies10 and will be important to a wide range of disciplines from science and humanities, as well as to the medical sector studying human genetic variation and health in African and African-descendant populations

31st Annual Meeting and Associated Programs of the Society for Immunotherapy of Cancer (SITC 2016) : part two

Background The immunological escape of tumors represents one of the main ob- stacles to the treatment of malignancies. The blockade of PD-1 or CTLA-4 receptors represented a milestone in the history of immunotherapy. However, immune checkpoint inhibitors seem to be effective in specific cohorts of patients. It has been proposed that their efficacy relies on the presence of an immunological response. Thus, we hypothesized that disruption of the PD-L1/PD-1 axis would synergize with our oncolytic vaccine platform PeptiCRAd. Methods We used murine B16OVA in vivo tumor models and flow cytometry analysis to investigate the immunological background. Results First, we found that high-burden B16OVA tumors were refractory to combination immunotherapy. However, with a more aggressive schedule, tumors with a lower burden were more susceptible to the combination of PeptiCRAd and PD-L1 blockade. The therapy signifi- cantly increased the median survival of mice (Fig. 7). Interestingly, the reduced growth of contralaterally injected B16F10 cells sug- gested the presence of a long lasting immunological memory also against non-targeted antigens. Concerning the functional state of tumor infiltrating lymphocytes (TILs), we found that all the immune therapies would enhance the percentage of activated (PD-1pos TIM- 3neg) T lymphocytes and reduce the amount of exhausted (PD-1pos TIM-3pos) cells compared to placebo. As expected, we found that PeptiCRAd monotherapy could increase the number of antigen spe- cific CD8+ T cells compared to other treatments. However, only the combination with PD-L1 blockade could significantly increase the ra- tio between activated and exhausted pentamer positive cells (p= 0.0058), suggesting that by disrupting the PD-1/PD-L1 axis we could decrease the amount of dysfunctional antigen specific T cells. We ob- served that the anatomical location deeply influenced the state of CD4+ and CD8+ T lymphocytes. In fact, TIM-3 expression was in- creased by 2 fold on TILs compared to splenic and lymphoid T cells. In the CD8+ compartment, the expression of PD-1 on the surface seemed to be restricted to the tumor micro-environment, while CD4 + T cells had a high expression of PD-1 also in lymphoid organs. Interestingly, we found that the levels of PD-1 were significantly higher on CD8+ T cells than on CD4+ T cells into the tumor micro- environment (p < 0.0001). Conclusions In conclusion, we demonstrated that the efficacy of immune check- point inhibitors might be strongly enhanced by their combination with cancer vaccines. PeptiCRAd was able to increase the number of antigen-specific T cells and PD-L1 blockade prevented their exhaus- tion, resulting in long-lasting immunological memory and increased median survival

Detection of the anti-androgenic effect of endocrine disrupting environmental contaminants using in vivo and in vitro assays in the three-spined stickleback

We have previously developed a novel in vitro assay that utilises cultures of primed female stickleback kidney cells for the screening of potential androgenic and anti-androgenic environmental contaminants. Stickleback kidney cells are natural targets for steroid hormones and are able to produce a protein, spiggin, in response to androgenic stimulation. We undertook a combined in vivo/in vitro study where we used the magnitude of spiggin production as an endpoint to test the anti-androgenic properties of the pharmaceutical androgen antagonist flutamide and three environmental contaminants: the organophosphate insecticide fenitrothion, the urea-based herbicide linuron and the fungicide vinclozolin. In vitro, kidney cells were exposed to a range of concentrations [from 10-14M (2.5pg/L) up to 10-6M (280μg/L)] of the test compounds alone for determining agonist activities, or together with 10-8M (3μg/L) dihydrotestosterone (DHT) for determining antagonist activities. An in vivo flow-trough aquarium-based study was carried out in parallel. Female sticklebacks were exposed to a range of concentrations of the same chemicals alone or in combination with DHT (5μg/L) for 21 days. All of the compounds significantly inhibited DHT-induced spiggin production in a concentration-dependent manner in both the in vitro (FN≥FL≥LN>VZ) and in vivo (FN>FL≥VZ>LN) assays. Fenitrothion and flutamide inhibited spiggin production in vitro at a concentration as low as 10-12M (P<0.05), while linuron and vinclozolin inhibited DHT-induced spiggin production at concentrations of 10-10M (P<0.05) and 10-6M (P<0.001) respectively. Similarly, fenitrothion and flutamide were the most potent chemicals in vivo and significantly reduced DHT-induced spiggin production at a concentration of 10μg/L and 25μg/L respectively (P<0.01). Both linuron and vinclozolin induced a significant decrease in DHT-induced spiggin production at a concentration of 100μg/L when tested in vivo. In addition, kidney cell primary culture was used to test the (anti-)androgenic effects of the major environmental contaminants: oestradiol (E2), nonylphenol (NP) and bisphenol A (BPA) for the first time in teleosts. We observed that these compounds were able to significantly inhibit spiggin production at high doses (E2: 270μg/L; NP: 2.2μg/L; BPA: 2.3μg/L). When tested in the absence of DHT, none of the compounds showed a significant agonistic activity in either in vivo or in vitro assays. Overall, our data further demonstrate that kidney cell primary culture is a reliable and a sensitive screening tool for the detection of (anti-)androgenic compounds. In addition, our study represents the first attempt to develop a combined in vivo/in vitro screening strategy for assessing the effects of (anti-)androgenic endocrine disrupters

The combined impact of plant-derived dietary ingredients and acute stress on the intestinal arachidonic acid cascade in Atlantic salmon (Salmo salar)

A study was conducted to assess the effect of substituting high levels of dietary fish oil (FO) and fishmeal (FM) for vegetable oil (VO) and plant protein (PP) on the intestinal arachidonic acid (AA) cascade in the carnivorous fish species Atlantic salmon. Four diets were fed to salmon over a period of 12 months, including a control FMFO diet, with varying replacements of plant-derived ingredients: 80 % PP and 35 % VO; 40 % PP and 70 % VO; 80 % PP and 70 %VO. Subsequently, fish were examined pre- (0 h) and post- (1 h) acute stress for blood parameters and intestinal bioactive lipidic mediators of inflammation (prostaglandins). Plasma cortisol responses were greatest in the FMFO group, while 80 % PP and 70 % VO fish exhibited increased plasma chloride concentrations. The n-3:n-6 PUFA ratio in intestinal glycerophospholipids from 70 % VO groups significantly decreased in both proximal and distal regions due to elevated levels of 18 : 2n-6 and the elongation/desaturation products 20 : 2n-6 and 20 : 3n-6. Increases in n-6 PUFA were not concomitant with increased AA, although the AA:EPA ratio did vary significantly. The 40 % PP and 70 % VO diet produced the highest intestinal AA:EPA ratio proximally, which coincided with a trend in elevated levels of PGF2α, PGE2 and 6-keto-PGF1α in response to stress. PGE2 predominated over PGF2α and 6-keto-PGF1α (stable metabolite of PGI2) with comparable concentrations in both intestinal regions. Cyclo-oxygenase-2 (COX-2) mRNA expression was an order of magnitude higher in distal intestine, compared with proximal, and was significantly up-regulated following stress. Furthermore, the 80 % PP and 70 % VO diet significantly amplified proximal COX-2 induction post-stress. Results demonstrate that high replacements with plant-derived dietary ingredients can enhance COX-2 induction and synthesis of pro-inflammatory eicosanoids in the intestine of salmon in response to acute physiological stress

Intercalibration exercise using a stickleback endocrine disrupter screening assay

The Organisation for Economic Cooperation and Development (OECD) is currently validating a short-term fish screening protocol for endocrine disrupters (estrogens, androgens, and their antagonists and aromatase inhibitors), using three core species: fathead minnow, Japanese medaka, and zebrafish. The main endpoints proposed for the first phase of validation of the screen are vitellogenin (VTG) concentration, gross morphology (secondary sexual characteristics and gonado-somatic index), and gonadal histopathology. A similar protocol is concurrently being developed in the United Kingdom using the three-spined stickleback, with identical endpoints to those for the core species and, in addition, a unique androgen-specific endpoint in the form of spiggin (glue protein) induction. To assess the suitability of this species for inclusion in the OECD protocol alongside the core species, an intercalibration was conducted using 17β-estradiol (a natural estrogen) and trenbolone (a synthetic androgen), thus mimicking a previous intercalibration with the core species. All three participating laboratories detected statistically significant increases in VTG in males after 14 d exposure to nominal concentrations of 100 ng/L 17β-estradiol and statistically significant increases in spiggin in females after 14 d exposure to nominal concentrations of 5,000 ng/L trenbolone. The stickleback screen is reliable, possessing both relevant and reproducible endpoints for the detection of potent estrogens and androgens. Further work is underway to assess the relevance and suitability of the screen for weakly acting estrogens, anti-androgens, and aromatase inhibitors

The genetic legacy of the expansion of Bantu-speaking peoples in Africa

AbstractWith the largest genomic dataset to date of Bantu-speaking populations, including newly generated data of modern-day and ancient DNA from previously unsampled regions in Africa, we shed fresh light on the expansion of peoples speaking Bantu languages that started ∼4000 years ago in western Africa. We have genotyped 1,740 participants, including 1,487 Bantu speakers from 143 populations across 14 African countries, and generated whole-genome sequences from 12 Late Iron Age individuals. Our results show that Bantu speakers received significant gene-flow from local groups in regions they expanded into. We show for the first time that genetic diversity amongst Bantu-speaking populations declines with distance from western Africa, with current-day Zambia and the DRC as possible crossroads of interaction. Using spatially explicit methods and correlating genetic, linguistic and geographical data, we provide cross-disciplinary support for a serial founder migration model. Finally, we discuss the utility of our dataset as an exhaustive modern-day African comparative dataset for ancient DNA studies. These new findings and data will be important to a wide range of disciplines from science and humanities as well as to the medical sector studying human genetic variation and health in African and African-descendant populations.One-sentence summaryA comprehensive genetic analysis of the expansion of people speaking Bantu languages reveals a complex history of serial founder events, variable levels of contact with local groups, and spread-over-spread events.</jats:sec