The dual origin of the peripheral olfactory system: placode and neural crest

<p>Abstract</p> <p>Background</p> <p>The olfactory epithelium (OE) has a unique capacity for continuous neurogenesis, extending axons to the olfactory bulb with the assistance of olfactory ensheathing cells (OECs). The OE and OECs have been believed to develop solely from the olfactory placode, while the neural crest (NC) cells have been believed to contribute only the underlying structural elements of the olfactory system. In order to further elucidate the role of NC cells in olfactory development, we examined the olfactory system in the transgenic mice Wnt1-Cre/Floxed-EGFP and P0-Cre/Floxed-EGFP, in which migrating NC cells and its descendents permanently express GFP, and conducted transposon-mediated cell lineage tracing studies in chick embryos.</p> <p>Results</p> <p>Examination of these transgenic mice revealed GFP-positive cells in the OE, demonstrating that NC-derived cells give rise to OE cells with morphologic and antigenic properties identical to placode-derived cells. OECs were also positive for GFP, confirming their NC origin. Cell lineage tracing studies performed in chick embryos confirmed the migration of NC cells into the OE. Furthermore, spheres cultured from the dissociated cells of the olfactory mucosa demonstrated self-renewal and trilineage differentiation capacities (neurons, glial cells, and myofibroblasts), demonstrating the presence of NC progenitors in the olfactory mucosa.</p> <p>Conclusion</p> <p>Our data demonstrates that the NC plays a larger role in the development of the olfactory system than previously believed, and suggests that NC-derived cells may in part be responsible for the remarkable capacity of the OE for neurogenesis and regeneration.</p

Increased level of tumour necrosis factor-alpha (TNF-α) on the skin of Japanese obese males: Measured by quantitative skin blotting

Objective: A state of chronic inflammation, characterized by an increased level of tumour necrosis factor-alpha (TNF-α), is often found in the obese population. The negative effects of elevated TNF-α are not limited to systemic metabolism. It also reportedly affects skin integrity. Recently, the relationship between obesity and skin fragility was reported; however, there has been little insight into how the level of TNF-α in the skin in situ is related to the severity of obesity. In this study, we aimed to measure the level of TNF-α on the skin and to find the relationship between obesity and the level of TNF-α detected on the skin. Methods: We used a novel, non-invasive method called quantitative skin blotting. Fifty-nine healthy (but some were classified as being overweight or obese) Japanese males were enrolled as subjects. The levels of TNF-α detected on the abdominal and thigh skin along with the body composition were measured, followed by a correlation analysis. Results: Significant positive correlations were found between the levels of TNF-α detected on the skin and the severity of obesity such as body mass index (BMI), body fat weight and visceral fat rating. Conclusion: We found that high levels of TNF-α were detected on the skin of Japanese obese males, which implied the higher TNF-α in the skin. The elevation of skin TNF-α may be one factor related to skin fragility that is often found in obese individuals. © 2016 John Wiley & Sons Ltd.Embargo Period 12 month

The Migratory Ability of Gonadal Germ Cells in the Domestic Chicken

The migratory ability of germ cells collected from gonads at different stages of embryonic development was investigated in the domestic chicken. In Experiment 1, primordial germ cells (PGCs) were collected from 2.5-day-old embryo. Also gonadal germ cells (GGCs) were collected from 6.5-, 10.5-, 14.5-, 18.5-, and 20.5-day-old embryos. PGCs and GGCs were labeled with the fluorescent dye PKH-26, and 20 fluorescently labeled PGCs or GGCs were injected into the vascular systems of 2-day-old recipient embryos. The total number of fluorescently labeled cells recovered from both the left and right gonads of the recipient embryos was counted 5 days after injection. The proportion of recipient embryos carrying fluorescently labeled cells was 100% when the donor GGCs were collected from 6.5-, and 10.5-day-old embryos. The proportion decreased when the donor GGCs were from embryos incubated for longer than 14.5 days. An inverse relationship was observed between the total number of fluorescently labeled cells in the recipient gonads and the age of the donor embryo. In Experiment 2, gonadal cell suspensions were prepared from the left gonads of newborn chicks and adult chickens. Gonadal cell suspensions were labeled with the fluorescent dye PKH-26 and injected into the vascular systems of 2-day-old recipient embryos. The proportions of recipient embryos with fluorescently labeled cells in their gonads were 100% (3/3), 100% (3/3), 100% (3/3), and 67% (2/3) when the injected gonadal cell suspension was from male newborn chicks, female newborn chicks, adult roosters, and adult hens, respectively. These results indicate the presence of migratory germ cells in the gonads of developing embryos until day 20.5 of incubation. Furthermore, these results also suggest the presence of migratory cells even in the sexually matured testes or ovaries

Effects of Ultraviolet Irradiation on the Migratory Ability of Primordial Germ Cells (PGCs) in the Domestic Chicken

The effect of ultraviolet (UV) irradiation on the ability of primordial germ cells (PGCs) to migrate toward the gonadal ridge was investigated in the domestic chicken. When PGCs were irradiated with UV (254nm, 0.9&plusmn;0.1&mu;W/cm2) the extent of nuclear damage, as determined by the comet assay, was positively correlated with the duration of UV irradiation in the range from 0 to 60 seconds. However, no further increase in nuclear damage was detected when the duration of UV irradiation was extended from 60 to 120 seconds. To evaluate the migratory ability of PGCs after UV irradiation, 15 fluorescent-labeled PGCs were transferred into the vascular system of 2-day-old embryos and the fluorescent-labeled PGCs present in the gonads of recipient embryos were counted 5 days later. When the duration of UV irradiation was less than 60 seconds, the number of fluorescent-labeled PGCs found in the gonads of the recipient embryos exceeded the number of transferred PGCs. In conclusion, the ability of PGCs to migrate toward the developing gonad is retained after exposure to UV irradiation that causes apparent damage to the nucleus

Intense Expression of GFP Gene in Gonads of Chicken Embryos by Transfecting Circulating Primordial Germ Cells in vitro and in vivo

The present study was carried out to develop techniques for introducing exogenous DNA into primordial germ cells (PGCs) and expressing the introduced DNA efficiently in the gonads of developing chicken embryos. PGCs circulating in the bloodstream (stages 14-15) were transfected with GFP gene in vitro or in vivo by lipofection or nucleofection. The manipulated PGCs successfully migrated to the germinal ridges and expressed GFP gene efficiently in the gonads of developing embryos. Intense GFP gene expression was observed in the gonads during the first 8 days following the transfection, during which period the sexual differentiation of gonads and germ cells (GCs) takes place. The GFP gene expression then gradually declined during subsequent embryonic development until hatching. When PGCs were transfected in vivo by lipofection with linearised plasmid DNA, GFP gene was detected in the gonads of 4.3% (19/442) of embryos examined at 20.5 days of culture, whereas less than 1% of embryos detected GFP gene in the gonads of embryos in which PGCs were transfected in vitro or with circular form plasmid DNA. In two of the embryos in which PGCs were transfected in vivo by lipofection with linearised plasmid DNA, GFP gene was expressed clearly in limited areas of the gonads of 20.5-day cultured embryos. The results obtained in this study suggest that the present in vitro and in vivo techniques for PGC manipulation provide a useful experimental system for studying gene functions in the sexual differentiation of gonads and GCs in early chicken embryos

Assessment of histopathology of wounds based on protein distribution detected by wound blotting

Background: Shortening the duration of healing based on an accurate assessment is important in pressure ulcer management. This study focused on the peroxidase and alkaline phosphatase activity detected by wound blotting, a non-invasive method of collecting wound exudate, to establish a non-invasive and point-of-care assessment method for analyzing the histopathology of wounds using an animal model. Methods: Wounds were created on the dorsal skin of rats. Peroxidase and alkaline phosphatase activities in the wound exudate were detected by wound blotting on post-wounding days 1, 4, 7, and 10. Wound tissue was collected on the same sampling days. Peroxidase and alkaline phosphatase activity within the tissue and myeloperoxidase were visualized. Two types of peroxidase activities were detected by wound blotting: ring and non-ring signals. The histopathological features were compared between wounds with ring and non-ring signals. Results: The wounds with ring signals showed a high level of peroxidase activity, and histological analysis demonstrated that the secreted or deviated peroxidase activity originated from myeloperoxidase, indicating a strong inflammation reaction within the tissue. The histopathology of wounds related to the alkaline phosphatase signals was not identified. Conclusion: The results suggested that ring signals indicated a strong inflammatory reaction and that they could be used to assess non-visible inflammation

Preferential Migration of Transferred Primordial Germ Cells to Left Germinal Ridge of Recipient Embryos in Chickens

Chicken primordial germ cells (PGCs) circulate in the bloodstream and migrate to germinal ridges. In order to assess the migration frequencies of PGCs to left or right germinal ridges, PGCs were transferred into the bloodstream of recipient embryos and analysed the presence of the donor PGC-derived mitochondrial DNA in the left or right gonad of embryos. First, minimum number of donor PGCs needed to detect donor-derived DNA in the gonads of recipient embryos incubated for 16.5 days were assessed, and found that a single PGC-derived DNA can be detected in the gonads. Then, a single PGC was transferred into the recipient bloodstream and analysed the presence of donor PGC-derived DNA in the left or right gonad of recipient embryos. When male PGCs were transferred into male or female recipient embryos, the donor-derived DNA was detected in the left gonad at the frequency of 61.5% (8/13) or 82.6% (19/23), respectively. On the other hand, when female PGCs were transferred into male or female recipient embryos, the donor-derived DNA was detected in the left gonads at the frequency of 72.2% (27/36) or 91.5% (43/47), respectively. The frequency of male or female PGCs migrating to the left germinal ridge of recipient embryos were 75.0% (27/36) or 83.1% (69/83), respectively, whereas the frequency of male or female recipient embryos attracting PGCs to their left germinal ridge were 69.4% (34/49) or 88.6% (62/70), respectively. These results suggest that female PGCs tended to migrate to the left germinal ridge more frequently than male PGCs, and female recipient embryos tended to attract PGCs in the left germinal ridge more frequently than male recipient embryos. This preferential migration of PGCs to left germinal ridge would be very important for female PGCs to differentiate normally and give rise to functional gametes efficiently