A small population of hypothalamic neurons govern fertility: the critical role of VAX1 in GnRH neuron development and fertility maintenance.

Fertility depends on the correct maturation and function of approximately 800 gonadotropin-releasing hormone (GnRH) neurons in the brain. GnRH neurons are at the apex of the hypothalamic-pituitary-gonadal axis that regulates fertility. In adulthood, GnRH neurons are scattered throughout the anterior hypothalamic area and project to the median eminence, where GnRH is released into the portal vasculature to stimulate release of luteinizing hormone (LH) and follicle-stimulating hormone (FSH) from the pituitary. LH and FSH then regulate gonadal steroidogenesis and gametogenesis. Absence of GnRH neurons or inappropriate GnRH release leads to infertility. Despite the critical role of GnRH neurons in fertility, we still have a limited understanding of the genes responsible for proper GnRH neuron development and function in adulthood. GnRH neurons originate in the olfactory placode then migrate into the brain. Homeodomain transcription factors expressed within GnRH neurons or along their migratory path are candidate genes for inherited infertility. Using a combined in vitro and in vivo approach, we have identified Ventral Anterior Homeobox 1 (Vax1) as a novel homeodomain transcription factor responsible for GnRH neuron maturation and fertility. GnRH neuron counts in Vax1 knock-out embryos revealed Vax1 to be required for the presence of GnRH-expressing cells at embryonic day 17.5 (E17.5), but not at E13.5. To localize the effects of Vax1 on fertility, we generated Vax1flox mice and crossed them with Gnrhcre mice to specifically delete Vax1 within GnRH neurons. GnRH staining in Vax1flox/flox:GnRHcre mice show a total absence of GnRH expression in the adult. We performed lineage tracing in Vax1flox/flox:GnRHcre:RosaLacZ mice which proved GnRH neurons to be alive, but incapable of expressing GnRH. The absence of GnRH leads to delayed puberty, hypogonadism and complete infertility in both sexes. Finally, using the immortalized model GnRH neuron cell lines, GN11 and GT1-7, we show that VAX1 is a direct regulator of Gnrh1 transcription by binding key ATTA sites within the Gnrh1 promoter. This study identifies VAX1 as a key transcription factor regulating GnRH expression and establishes VAX1 as a novel candidate gene implicated in heritable infertility

The Muscadine Experience: Adding Value to Enhance Profits

The University of Arkansas Division of Agriculture received a grant from the National Research Initiative (NRI), CSREES USDA. The purpose was to help small- and medium-sized farmers and entrepreneurs enhance the viability of their farms through the establishment of vineyards, on-farm wineries, and production of value-added products from grapes and grape by-products. This publication looks at efforts by the UA Grape and Wine Research Program to enhance the profitability of muscadine grapes. Included are discussions of research designed to develop the market potential of muscadines as fresh fruit and as value-added products such as juice, wine, sweet spreads, vinegar, and dried products. The skin and seeds of muscadines have traditionally been considered waste; however, recent research has shown that they contain nutraceutical components. Reports are included of research to quantify these nutraceuticals and to develop products containing them

The Muscadine Experience: Adding Value to Enhance Profits

The University of Arkansas Division of Agriculture received a grant from the USDA’s Initiative for Future Agriculture and Food Systems (IFAFS) program. The purpose was to help small- and medium-sized farmers and entrepreneurs become more profitable and therefore add stability to the family farm. One approach to doing this is to investigate opportunities to enhance profits by adding value to traditional raw products

MORPHOLOGY, REPRODUCTION, SEASONAL ACTIVITY AND HABITAT USE OF A NORTHERN POPULATION OF THE SMOOTH GREENSNAKE (OPHEODRYS VERNALIS)

The Smooth Greensnake (Opheodrys vernalis) is a small, slender, oviparous, colubrid snake that is widely distributed in North America. Nonetheless, there have been few studies on this species, and little is known about Canadian populations. The objective of this study was to examine morphology, reproduction, seasonal activity and habitat use of a northern population of the Smooth Greensnake. Individuals were captured during the summers of 2007-2010 in southwestern Manitoba, Canada. Females were larger and relatively heavier than males, but clutch size did not consistently increase with body size. In addition, 59% (on average) of available adult females were gravid in any given year, suggesting that females may not reproduce each year. Males had relatively longer heads and longer tails than females. Males were more common in early August; otherwise, females were more common. The peak of male activity in August suggests that fall mating might occur in this species, but this was not confirmed. Finally, Smooth Greensnakes were most commonly found in grassland, and there were no differences in habitat use between the sexes. Further research on northern populations of Smooth Greensnakes would provide valuable information on this little-studied species

Impacts of programs and organizations on the adoption of sustainable land management technologies in Uganda:

The government of Uganda is currently decentralizing many of its services including those directly related to agriculture and the environment. Non-government organizations (NGOs) and community-based organizations (CBOs) are being asked to take the lead in the provision of government services such as agricultural extension during the transition to demand driven fee-for-service. This paper explores the role of government programs, NGOs and CBOs in the adoption of land management technologies. We find that government programs were better distributed throughout Uganda and were more likely to operate in poorer areas than NGOs and CBOs. This raises the question of whether or not incentives should be provided for NGOs and CBOs to locate or evolve in less-favored areas. Our analysis of household level involvement in organizations between 1990 and 2000 indicates that female-headed households, households with higher proportions of women, and households with higher levels of natural resource dependence were more likely than other households to be involved in organizations whose main focus was not agriculture or the environment. We also found that social capital is an important determinant of organizational participation. The results of our analysis indicate that the presence of an agriculture or environment focused program or organization at the community level had a negative effect on the adoption of animal manuring and a positive affect on the adoption of pesticides. This suggests that spillover effects of programs and organizations may be greater for technologies that have short-term benefits, and which require some degree of coordination to be most effective. Household level involvement in an agriculture or environment focused organization had a positive effect on the adoption of inorganic fertilizer and mulching. Adoption of land management technologies such as manuring that yield longer-term benefits apparently do not spill over to non-participants in local programs and organizations. Thus, direct involvement of households in programs and organizations that promote such technologies may be necessary to ensure technology diffusion throughout communities. This information may be taken as an indicator of the effectiveness or impact of agriculture and environment focused organizations in Uganda, and should be considered in the broader context of the government devolution of services to NGOs and CBOs. Our findings indicate that careful consideration needs to be given to the potential for NGOs and CBOs to fulfill the roles traditionally filled by government programs in the context of land management. The limited impact of agriculture and environment focused organizations on technology adoption is discouraging though may be linked to the limited profitability of technology adoption in the short-run.Human capital, technology, Gender, Natural resource management, Agricultural technology, Agricultural growth,

Estimating the Wage Elasticity of Labour Supply to a Firm: What Evidence Is There for Monopsony?

In this paper we estimate the elasticity of the labour supply to a firm, using data from the Household, Income and Labour Dynamics in Australia (HILDA) Survey. Estimation of this elasticity is of particular interest not only in its own right but also because of its relevance to the debate about the competitiveness of labour markets. The essence of monopsonistically competitive labour markets is that labour supply to a firm is imperfectly elastic with respect to the wage rate. The intuition is that, where workers have heterogeneous preferences or face mobility costs, firms can offer lower wages without immediately losing their workforce. This is in contrast to the perfectly competitive extreme, in which the elasticity is infinite. Therefore a simple test of whether labour markets are perfectly or imperfectly competitive involves estimating the elasticity of the labour supply to a firm. We find that the Australian wage elasticity of labour supply to a firm is around 0.71, only slightly smaller than the figure of 0.75 reported by Manning (2003) for the UK. These estimates are so far from the perfectly competitive assumption of an infinite elasticity that it would be difficult to make a case that labour markets are perfectly competitive.monopsony, imperfect competition, separation, labour supply elasticity

The role of trees for sustainable management of less-favored lands: the case of eucalyptus in Ethiopia

In recent years the planting of eucalyptus trees in Ethiopia has expanded from State owned plantations to community woodlots and household compounds. In an environment suffering from severe woody biomass shortages water scarcity, erosion and land degradation, fast growing and resilient eucalyptus species perform better than most indigenous woodland and forest tree species (as well as most crops). In addition to increasing biomass and providing ground cover, the sale of eucalyptus poles and products has substantial potential to raise farm incomes, reduce poverty, increase food security and diversify smallholder-farming systems in less-favored areas of northern Ethiopia. Despite the potential for eucalyptus to improve rural livelihoods in northern Ethiopia in 1997, the regional government of Tigray imposed a ban on eucalyptus tree planting on farmlands. The regional government promotes planting of eucalyptus and other species in community woodlots, and has recently begun to allow private planting of eucalyptus on community wasteland and steep hillsides. In this paper, we review the debate about the ecological impacts of eucalyptus trees, as well as the economic factors that influence whether smallholders invest in these trees. Ex ante benefit-cost analysis based on community level survey data from Tigray illustrates that under most conditions planting eucalyptus trees yields high rates of return, well above 20% under most circumstances. The effect of variable harvest rates, the costs of decreased crop production when eucalyptus trees are planted on farmlands, and differences between administrative zones are considered relative to our base case in our rate of return estimates. The importance of fast growing tree species that can accommodate the high discount rates associated with smallholders in this region is emphasized.Tree planting., Ecology., Ethiopia., Land degradation.,

Estimating the Wage Elasticity of Labour Supply to a Firm: Is there Monopsony Down-under?

In this paper we estimate the elasticity of the labour supply to a firm, using data from the Household, Income and Labour Dynamics in Australia (HILDA) Survey. Estimation of this elasticity is of particular interest because of its relevance to the debate about the competitiveness of labour markets. The essence of monopsonistically competitive labour markets is that labour supply to a firm is imperfectly elastic with respect to the wage rate. The intuition is that, where workers have heterogeneous preferences or face mobility costs, firms can offer lower wages without immediately losing their workforce. This is in contrast to the perfectly competitive extreme, in which the elasticity is infinite. Therefore a simple test of whether labour markets are perfectly or imperfectly competitive involves estimating the elasticity of the labour supply to a firm. We do this, following the modelling strategy of Manning (2003), and find that the Australian wage elasticity of labour supply to a firm is around 0.71, only slightly smaller than the figure of 0.75 reported for the UK. These estimates are so far from the perfectly competitive assumption of an infinite elasticity that it would be difficult to make a case that labour markets are perfectly competitive.monopsony, imperfect competition, separation, labour supply elasticity