Do Conservation Easements Reduce Land Prices? The Case of South Central Wisconsin

While theory strongly suggests that restricting development rights should reduce land prices, empirical evidence of this effect has been notoriously hard to obtain. Indeed, largely based on this difficulty a Congressional committee has recently recommended that tax benefits for such restrictions be severely curtailed. We collect data on 131 land transactions in South Central Wisconsin, including 19 cases of development-restricted parcels. When we use the whole sample to estimate the impact of conservation easements we replicate the results of Nickerson and Lynch (2001), finding a negative but statistically insignificant effect. However we then show that when the sample is appropriately restricted to a more homogenous group of land parcels, our ability to detect an effect increases dramatically. In particular, for vacant agricultural land we find a statistically significant negative impact of conservation easements that ranges up to 50% of land valuesland use, valuation of development rights, conservation easements, hedonic regression

Do Conservation Easements Reduce Land Prices? The Case of South Central Wisconsin

While theory strongly suggests that restricting development rights should reduce land prices, empirical evidence of this effect has been notoriously hard to obtain. Indeed, largely based on this difficulty a Congressional committee has recently recommended that tax benefits for such restrictions be severely curtailed. We collect data on 131 land transactions in South Central Wisconsin, including 19 cases of developmentrestricted parcels. When we use the whole sample to estimate the impact of conservation easements we replicate the results of Nickerson and Lynch (2001), finding a negative but statistically insignificant effect. However we then show that when the sample is appropriately restricted to a more homogenous group of land parcels, our ability to detect an effect increases dramatically. In particular, for vacant agricultural land we find a statistically significant negative impact of conservation easements that ranges up to 50% of land values.

Harakeke: Enhancing Māori Student Engagement and Achievement in a Mainstream Primary School

Ministry of Education research indicates that the inclusion of culture and te reo Māori in teaching can help improve Māori student education. If students can find the links between what is being taught and the relevance to their own lives then information will be easier to retain. Research has also shown that environmental education provides relevant learning that can connect students to their world. Māori indigenous knowledge (IK) and environmental education (EE) share many commonalities. One such similarity is the relationship between tangata (people) and nature. While the sometimes destructive nature of this relationship has lead to global environmental issues, this study explores the combination of IK and EE to enhance Māori student engagement and achievement in a mainstream primary school. An intervention unit based on harakeke was designed delivered in a Year 5/6 boys' only class in a suburban mainstream primary school, over a 10 week period. The environmental and socio-cultural significance of harakeke enabled a range of kaupapa (themes) to be included in the unit. This included; eeling and how to make and use a hinaki (eel/fish trap), karakia (prayer) and the relevance when harvesting kai (food) and resources. Each kaupapa also provided the opportunity for students to increase their te reo Māori vocabulary, with the introduction of kaupapa specific words. The Māori kaupapa also enabled the students to view EE from a Māori perspective, including the introduction of rahui - a form of conservation. The findings indicated that the incorporation of a Māori kaupapa strengthened student engagement, improved student use of te reo Māori, improved the selfesteem and confidence for some students, increased students' awareness of harakeke and the value and versatility of the plant, and increased their awareness from a Māori perspective on sustainable harvesting. Bringing Māori kaupapa into the classroom allowed the classroom teacher, who was Māori, the opportunity to share her own lived experiences of IK, as these are passed down from generation to generation, and people are born into them. The Page | iii familiarity of whanau offered the teacher the opportunity to bring this concept into the classroom and teach values that could flow into all curriculum areas while strengthening relationships between the teacher and student, student and student and teacher and student whanau. This study has shown that both IK and EE, while each complex in their own right, have the ability to provide a holistic curriculum approach that can lead to engagement and achievement by Māori students in a mainstream school

The use of isolated peripheral lymphocytes and human whole blood in the comet assay

YesThe comet assay is a sensitive method used to detect DNA damage, measuring DNA breaks and alkali labile lesions in eukaryotic cells. Here, the use of whole blood in the alkaline gel electrophoresis method is described. Two hundred and seventy blood samples from individuals were examined: 120 healthy individuals, 65 suspected or pre-cancerous individuals and 85 cancer patients. Each sample was divided into two identical volumes in different falcon tubes. The blood was prepared and stored by adding the same amount of RPMI medium and 10% DMSO. Using the Student’s t-Test, the data showed a p value = 0.59 for Olive tail moment (OTM) and 0.16 for % tail DNA, and no statistically significant differences between the two methods, with or without treatment. In conclusion, using whole blood instead of isolated lymphocytes saves time, is still very sensitive and requires less than 20 µL of blood from each individual

Objetivación del límite de una función: ¿pensamiento empírico o pensamiento teórico?

Presentamos un avance del proyecto de tesis de doctorado que estamos realizando en el marco del doctorado en educación, línea de educación matemática, de la Universidad de Antioquia. Este estudio tiene como propósito analizar la objetivación del concepto de límite de una función, de alumnas de grado once, a través del desarrollo de su pensamiento teórico. La perspectiva histórico-cultural de la educación sirve de fundamentación teórica en esta investigación, en especial la teoría de la actividad. El camino metodológico a seguir es de orden cualitativo, desde un paradigma crítico-dialéctico, y una investigación participante. El trabajo de campo se realizará en una institución escolar pública de Medellín

Genotoxic and antigenotoxic properties of selenium compounds in the in vitro

Selenium is known to possess both genotoxic and antigenotoxic properties. In the present study, we have evaluated the genotoxicity and antigenotoxicity of three selenium compounds (sodium selenate, sodium selenite and selenous acid) by measuring in vitro micronucleus induction. Assays were conducted in whole blood lymphocytes and in the TK6 lymphoblastoid cell line, with and without co-treatment with potassium dichromate, a known genotoxic compound. In general, the compounds were more active in TK6 cells than they were in blood lymphocytes. Only 1 μM selenous acid increased the frequency of binucleated cells containing micronuclei (BNMN) in blood lymphocytes, while all three selenium compounds increased BNMN in TK6 cells. In addition, combinations of selenous acid and potassium dichromate resulted in lower frequencies of BNMN than potassium dichromate alone in blood lymphocytes, while combinations of sodium selenate and potassium dichromate produced lower frequencies of BNMN than potassium dichromate alone in TK6 cells. The concentrations of selenium compounds that were used, in combination with the medium components and the biological physiology of the whole blood lymphocytes and TK6 cells, could have affected the redox potential of the compounds, switching the chemicals from a pro-oxidant to antioxidant status and vice-versa. The lower activities of the compounds in blood lymphocytes may be due to the protective effects of blood components. The results indicate that the genotoxic and antigenotoxic properties of selenium compounds are highly dependent upon the conditions under which they are evaluated

Diethylstilbestrol induces oxidative DNA damage, resulting in apoptosis of spermatogonial stem cells in vitro

YesThe spermatogonial stem cells (SSCs) are the only germline stem cells in adults that are responsible for the transmission of genetic information from mammals to the next generation. SSCs play a very important role in the maintenance of progression of spermatogenesis and help provide an understanding of the reproductive biology of future gametes and a strategy for diagnosis and treatment of infertility and male reproductive toxicity. Androgens/oestrogens are very important for the suitable maintenance of male germ cells. There is also evidence confirming the damaging effects of oestrogen-like compounds on male reproductive health. We investigated the effects in vitro, of diethylstilbestrol (DES) on mouse spermatogonial stem cells separated using Staput unit-gravity velocity sedimentation, evaluating any DNA damage using the Comet assay and apoptotic cells in the TUNEL assay. Immunocytochemistry assays showed that the purity of isolated mouse spermatogonial cells was 90%, and the viability of these isolated cells was over 96%. Intracellular superoxide anion production (O2−) in SSCs was detected using p-Nitro Blue Tetrazolium (NBT) assay. The viability of cells after DES treatment was examined in the CCK8 (cell counting kit-8) cytotoxicity assay. The results showed that DES-induced DNA damage causes an increase in intracellular superoxide anions which are reduced by the flavonoid, quercetin. Investigating the molecular mechanisms and biology of SSCs provides a better understanding of spermatogonial stem cell regulation in the testis

In vitro responses to known in vivo genotoxic agents in mouse germ cells

YesGenotoxic compounds have induced DNA damage in male germ cells and have been associated with adverse clinical outcomes including enhanced risks for maternal, paternal and offspring health. DNA strand breaks represent a great threat to the genomic integrity of germ cells. Such integrity is essential to maintain spermatogenesis and prevent reproduction failure. The Comet assay results revealed that the incubation of isolated germ cells with n-ethyl-n-nitrosourea (ENU), 6-mercaptopurine (6-MP) and methyl methanesulphonate (MMS) led to increase in length of Olive tail moment and % tail DNA when compared with the untreated control cells and these effects were concentration-dependent. All compounds were significantly genotoxic in cultured germ cells. Exposure of isolated germ cells to ENU produced the highest concentration-related increase in both DNA damage and gene expression changes in spermatogonia. Spermatocytes were most sensitive to 6-MP, with DNA damage and gene expression changes while spermatids were particularly susceptible to MMS. Real-time PCR results showed that the mRNA level expression of p53 increased and bcl-2 decreased significantly with the increasing ENU, 6-MP and MMS concentrations in spermatogonia, spermatocytes and spermatids respectively for 24 hr. Both are gene targets for DNA damage response and apoptosis. These observations may help explain the cell alterations caused by ENU, 6-MP and MMS in spermatogonia, spermatocytes and spermatids. Taken together, ENU, 6-MP and MMS induced DNA damage and decreased apoptosis associated gene expression in the germ cells in vitro.Libyan Governmen

Germ Cell Responses to Doxorubicin Exposure in Vitro

YesAnthracyclines such as doxorubicin (Dox), widely used to treat various types of tumours, may result in induced testicular toxicity and oxidative stress. The present investigation was designed to determine whether exposure of isolated and purified mouse germ cells to Dox induces DNA damage in the form of strand breaks (presumably) resulting in apoptosis and to investigate the relative sensitivity of specific cell types. DNA damage was assessed using the Comet assay and the presence of apoptosis was determined by TUNEL assay. Isolated mouse germ cells were treated with different concentrations (0.05, 0.5 and 1 mM, respectively) of Dox, and fixed 1 h after treatment. The incidences of both DNA damage shown by single cell gel-electrophoresis and of apoptosis increased significantly in each specific cell type in a concentration-dependent manner. The DNA damage and apoptosis incidences gradually increased with concentration from 0.05 to 1 mM with Dox. Our results indicate that apoptosis plays a vital role in the induction of germ cell phase-specific toxicity caused by Dox with pre-meiotically and meiotically dividing spermatogonia and spermatocytes respectively as highly susceptible target cells.Higher Education Funding Council for England (HEFCE

Silver nanoparticle-mediated cellular responses in isolated primary Sertoli cells in vitro

YesThe present study explored the mechanism of cytotoxic and genotoxic effects of AgNPs on a primary culture of mouse Sertoli cells in vitro. To understand the possible molecular mechanisms of testicular lesions following exposure to AgNPs, isolated Sertoli cells were exposed to 5, 10, or 15 μg/ml. DNA damage in the Comet assay and apoptosis in the TUNEL assay were evaluated. The mRNA expression of p53 and bcl-2 genes and their proteins involved in apoptosis was also investigated. The antioxidant status of treated Sertoli cells was determined by measuring superoxide dismutase (SOD-1), catalase (CAT), and glutathione peroxidase (GPX-1) and superoxide dismutase (SOD-1) using quantitative polymerase chain reaction (qPCR)qPCR. The superoxide anions were detected using the nitroblue tetrazolium (NBT) reduction assay. Results indicated that AgNP exposure causes increased oxidative stress levels. The activation of p53, repression of bcl-2 and reduction of endogenous antioxidant enzymes were also involved in these mechanistic pathways, leading to reduced cell numbers and cell detachment.The Sponsorship of the Libyan Government of a PhD studentship to Khaled Haba