Phenotypic plasticity in growth and fecundity induced by strong population fluctuations affects reproductive traits of female fish

Fish are known for their high phenotypic plasticity in life‐history traits in relation to environmental variability, and this is particularly pronounced among salmonids in the Northern Hemisphere. Resource limitation leads to trade‐offs in phenotypic plasticity between life‐history traits related to the reproduction, growth, and survival of individual fish, which have consequences for the age and size distributions of populations, as well as their dynamics and productivity. We studied the effect of plasticity in growth and fecundity of vendace females on their reproductive traits using a series of long‐term incubation experiments. The wild parental fish originated from four separate populations with markedly different densities, and hence naturally induced differences in their growth and fecundity. The energy allocation to somatic tissues and eggs prior to spawning served as a proxy for total resource availability to individual females, and its effects on offspring survival and growth were analyzed. Vendace females allocated a rather constant proportion of available energy to eggs (per body mass) despite different growth patterns depending on the total resources in the different lakes; investment into eggs thus dictated the share remaining for growth. The energy allocation to eggs per mass was higher in young than in old spawners and the egg size and the relative fecundity differed between them: Young females produced more and smaller eggs and larvae than old spawners. In contrast to earlier observations of salmonids, a shortage of maternal food resources did not increase offspring size and survival. Vendace females in sparse populations with ample resources and high growth produced larger eggs and larvae. Vendace accommodate strong population fluctuations by their high plasticity in growth and fecundity, which affect their offspring size and consequently their recruitment and productivity, and account for their persistence and resilience in the face of high fishing mortality.     

Feeder-free Derivation of Melanocytes from Human Pluripotent Stem Cells

Human pluripotent stem cells (hPSCs) represent a platform to study human development in vitro under both normal and disease conditions. Researchers can direct the differentiation of hPSCs into the cell type of interest by manipulating the culture conditions to recapitulate signals seen during development. One such cell type is the melanocyte, a pigment-producing cell of neural crest (NC) origin responsible for protecting the skin against UV irradiation. This protocol presents an extension of a currently available in vitro Neural Crest differentiation protocol from hPSCs to further differentiate NC into fully pigmented melanocytes. Melanocyte precursors can be enriched from the Neural Crest protocol via a timed exposure to activators of WNT, BMP, and EDN3 signaling under dual-SMAD-inhibition conditions. The resultant melanocyte precursors are then purified and matured into fully pigmented melanocytes by culture in a selective medium. The resultant melanocytes are fully pigmented and stain appropriately for proteins characteristic of mature melanocytes.     

Embryonic development of adriatic sturgeon,Acipenser naccarii (Bonaparte 1836), in farming conditions: a guide

The sequence and timing of the embryonic development of Adriatic sturgeon (Acipenser naccarii) are described at a constant temperature (17 ± 1 °C), from fertilisation to hatch in a hatchery. Fertilised eggs, obtained from one female and two males, were held in a flow‐through system. On the first day, embryos were sampled every 20 min during the first 12 h, and every 40 min in the following 12 h. Embryos were sampled hourly on the second day. On the third and fourth days, embryos were sampled every 2 h, and every 3 h on the fifth and sixth days. The first cleavage furrow appeared at 1 h 40 min postfertilisation. Blastulation concluded at 12 HPF (hours postfertilisation), when the dorsal blastopore lip formed. The completion of gastrulation was at 18 HPF, closing of the neural tube at 23 HPF and formation of the s‐shape heart at 31 HPF. The mass hatch occurred at 120 HPF. A. naccarii is a relatively common sturgeon species in aquaculture and possesses similar developmental patterns to those of other sturgeons; hence, we can use this species as a model for further studies about sturgeon species which are more difficult to breed artificially. Information about the embryonic development of the Adriatic sturgeon could assist restocking programmes.     

Keratinocytes derived from embryonic stem cells induce wound healing in mice

The skin plays an important role in defending the body against the environment. Treatments for burns and skin injuries that use autologous or allogenic skin grafts derived from adult or embryonic stem cells are promising. Embryonic stem cells are candidates for regenerative and reparative medicine. We investigated the utility of keratinocyte-like cells, which are differentiated from mouse embryonic stem cells, for wound healing using a mouse surgical wound model. Mice were allocated to the following groups: experimental, in which dressing and differentiated cells were applied after the surgical wound was created; control, in which only the surgical wound was created; sham, in which only the dressing was applied after the surgical wound was created; and untreated animal controls with healthy skin. Biopsies were taken from each group on days 3, 5 and 7 after cell transfer. Samples were fixed in formalin, then stained with Masson’s trichrome and primary antibodies to interleukin-8 (IL-8), fibroblast growth factor-2 (FGF-2), monocyte chemoattractant protein-1 (MCP-1), collagen-1 and epidermal growth factor (EGF) using the indirect immunoperoxidase technique for light microscopy. Wound healing was faster in the experimental group compared to the sham and control groups. The experimental group exhibited increased expression of IL-8, FGF-2 and MCP-1 during early stages of wound healing (inflammation) and collagen-1 and EGF expression during late stages of wound healing (proliferation and remodeling). Keratinocytes derived from embryonic stem cells improved wound healing and influenced the wound healing stages.     

Lysosomal Signaling Licenses Embryonic Stem Cell Differentiation via Inactivation of Tfe3

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Cryopreservation of mouse embryoid bodies

Cryopreservation of embryonic stem (ES) cells is essential to establish them as a resource for regenerative therapy. We evaluated survival adhesion rate, cell structure, gene expression, and multipotency of frozen and thawed embryoid bodies (EBs) derived from mouse ES cells. EBs were cryopreserved using the BICELL and the Program Freezer. After one week the EBs were thawed and cultured. EBs prepared in the Program Freezer had the highest survival adhesion (Program Freezer; 55-69%, BICELL; 30-38%). Though many cells in the thawed EBs were damaged, some were not, especially those prepared in the Program Freezer. RT-PCR analysis showed that genes characteristic of the three embryonic germ layers were expressed in thawed EBs cultured for one week. EBs transplanted into mice formed teratomas consisting of cells derived from the three germ layers. In conclusion, EBs frozen in the Program Freezer had higher survival adhesion rates compared to the BICELL and formed differentiated cells characteristic of the three embryonic germ layers.