26 research outputs found

    Characterization of spermatogonial stem cell maturation and differentiation in neonatal mice

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    Initiation of the first wave of spermatogenesis in the neonatal mouse testis is characterized by the differentiation of a transient population of germ cells called gonocytes found in the center of the seminiferous tubule. The fate of gonocytes depends upon these cells resuming mitosis and developing the capacity to mi-grate from the center of the seminiferous tubule to the basement membrane. This process begins approximately Day 3 postpartum in the mouse, and by Day 6 postpartum differentiated type A spermatogonia first appear. It is essential for continual sper-matogenesis in adults that some gonocytes differentiate into spermatogonial stem cells, which give rise to all differentiating germ cells in the testis, during this neonatal period. The presence of spermatogonial stem cells in a population of cells can be assessed with the use of the spermatogonial stem cell transplan-tation technique. Using this assay, we found that germ cells from the testis of Day 0–3 mouse pups can colonize recipient testes but do not proliferate and establish donor-derived spermatogen-esis. However, germ cells from testes of Day 4–5 postpartum mice colonize recipient testes and generate large areas of donor-derived spermatogenesis. Likewise, germ cells from Day 10, 12, and 28 postpartum animals and adult animals colonize and es-tablish donor-derived spermatogenesis, but a dramatic reduction in the number of colonies and the extent of colonization occurs from germ cell donors Days 12–28 postpartum that continues in adult donors. These results suggest spermatogonial stem cells are not present or not capable of initiating donor-derived sper-matogenesis until Days 3–4 postpartum. The analysis of germ cell development during this time frame of development and spermatogonial stem cell transplantation provides a unique sys-tem to investigate the establishment of the stem cell niche with-in the mouse testis. gamete biology, gametogenesis, sperm, spermatogenesi

    "Stop talking around projects and talk about solutions" : positioning health within infrastructure policy to achieve the sustainable development goals

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    Purpose and setting: Infrastructure is a global multi-trillion dollar market presenting many opportunities and risks for sustainable development. This article aims to foster better conceptualisation of the connections and tensions between infrastructure policy and public health in the light of the Sustainable Development Goals, especially ‘good health and wellbeing’ (number 3) and ‘industry, innovation and infrastructure’ (number 9), based on findings from interviews with a purposive sample of senior practicing Australian infrastructure policy makers. Principal findings: We use an institutional framework to explore the ideas, actors, rules and mandates, and procedures underpinning the inclusion of health in infrastructure policy. Informants defined infrastructure as the construction and provision of services that facilitate economic, environmental and social outcomes. The tendency to default to infrastructure as essential for economic success has fundamental challenges for the SDGs, particularly the politically driven pursuit of ‘mega-project’ legacies, sector-specific siloed governance arrangements, and inadequate conceptualisations of costs and benefits. Conclusions: Public health and infrastructure policy are mutually re-enforcing given they both concern the public interest with implications for all 17 SDGs. Positioning health and wellbeing as fundamental societal outcomes from infrastructure decisions would go a long way to helping achieve the SDGs

    Development of Two Animal Models To Study the Function of Vibrio parahaemolyticus Type III Secretion Systems

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    Vibrio parahaemolyticus is an emerging food- and waterborne pathogen that encodes two type III secretion systems (T3SSs). Previous studies have linked type III secretion system 1 (T3SS1) to cytotoxicity and T3SS2 to intestinal fluid accumulation, but animal challenge models needed to study these phenomena are limited. In this study we evaluated the roles of the T3SSs during infection using two novel animal models: a model in which piglets were inoculated orogastrically and a model in which mice were inoculated in their lungs (intrapulmonarily). The bacterial strains employed in this study had equivalent growth rates and beta-hemolytic activity based on in vitro assays. Inoculation of 48-h-old conventional piglets with 10 11 CFU of the wild-type strain (NY-4) or T3SS1 deletion mutant strains resulted in acute, self-limiting diarrhea, whereas inoculation with a T3SS2 deletion mutant strain failed to produce any clinical symptoms. Intrapulmonary inoculation of C57BL/6 mice with the wild-type strain and T3SS2 deletion mutant strains (5 × 10 5 CFU) induced mortality or a moribund state within 12 h (80 to 100% mortality), whereas inoculation with a T3SS1 deletion mutant or a T3SS1 T3SS2 double deletion mutant produced no mortality. Bacteria were recovered from multiple organs regardless of the strain used in the mouse model, indicating that the mice were capable of clearing the lung infection in the absence of a functional T3SS1. Because all strains had a similar beta-hemolysin phenotype, we surmise that thermostable direct hemolysin (TDH) plays a limited role in these models. The two models introduced herein produce robust results and provide a means to determine how different T3SS1 and T3SS2 effector proteins contribute to pathogenesis of V. parahaemolyticus infection
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