Glandular structures in the major interlobular and extrapancreatic ducts in the guinea pig

The morphology of the pancreatic duct system did not receive much attention as compared to the microanatomy of the exocrine and endocrine pancreas. The histological peculiarities of the excretory duct system are of major importance especially in laboratory animals like guinea pigs. The paper describes the histological peculiarities of the major interlobular and extrapancreatic ducts in guinea pigs. The pancreatic tissue samples were collected from five guinea pigs. For histological investigation, several pancreatic fragments underwent fixation in 10% buffered formalin and were later processed by the standard paraffin technique. Subsequentially, tissue sections were stained by Goldner's trichrome staining. The mucous substances were assessed by Alcian blue and Periodic acid–Schiff staining methods. The interlobular and main pancreatic ducts in the guinea pig present a simple columnar epithelium surrounded by a thick layer of dense connective tissue. The aforementioned epithelium of the main pancreatic ducts includes principal cells, goblet cells and basal cells. Additionally, the ductal epithelium presents occasional unicellular multiloculated intraepithelial mucous glands and prominent extraepithelial glands. The latter adopts a simple or compound tubular feature. The mucus elaborated by the three glandular types is mostly neutral in goblet cells, predominantly acidic in extraepithelial ductal glands, and a similar amount of acidic and neutral mucin in intraepithelial glands. In conclusion, the epithelium-associated mucous glands in the interlobular and main pancreatic ducts in the guinea pig are restricted not only to goblet cells. A substantial mucous discharge probably with a protecting role against irritative pancreatic juice derives from the main ductal intraepithelial and extraepithelial glands.     

Designing sustainable agriculture education: Academics’ suggestions for an undergraduate curriculum at a land grant university

Historically, land grant universities and their colleges of agriculture have been discipline driven in both their curricula and research agendas. Critics call for interdisciplinary approaches to undergraduate curriculum. Concomitantly, sustainable agriculture (SA) education is beginning to emerge as a way to address many complex social and environmental problems. University of California at Davis faculty, staff, and students are developing an undergraduate SA major. To inform this process, a web-based Delphi survey of academics working in fields related to SA was conducted. Faculty from colleges and universities across the US were surveyed. Participants suggested that students needed knowledge of natural and social science disciplines relating to the agri-food system. In addition, stakeholders suggested students learn through experiences that link the classroom to field work, engaging a broad range of actors within applied settings. Stakeholders also emphasized the need for interdisciplinary and applied scholarship. Additionally, they proposed a range of teaching and learning approaches, including many practical experiences. Given the diverse suggestions of content knowledge and means of producing knowledge, the survey presented unique challenges and called into question the epistemological and pedagogical norms currently found in land grant colleges of agriculture. This study has implications for land grant universities seeking to develop undergraduate curriculum appropriate to the field of SA. Damian M. Parr is a doctoral student of Agricultural and Environmental Education, in the School of Education at the University of California at Davis. His professional interests include organic farming, sustainable agriculture, experiential and transformational learning, critical pedagogy, and participatory action research. He is currently working on linking on-campus student initiated sustainable farm and food systems projects to curricula at land grant universities Cary J. Trexler is an assistant professor of Agricultural and Environmental Education at the University of California at Davis where he teaches courses in the history of agricultural education, experiential learning, and research methods for practicing teachers. His research focuses on experiential learning, sustainable agriculture education, and needs of teachers and informal educators within the context of the agri-food system Navina R. Khanna is a graduate student pursuing an MS in International Agricultural Development at the University of California at Davis. She is committed to facilitating community dialogue and education about sustainability issues. Her work at the university focuses on the process and goal of sustainability in agricultural education and campus food system sustainability. Her primary professional interests include democratic participatory process in agri-food system sustainability and urban revitalization Bryce T. Battisti is a doctoral student of Agricultural and Environmental Education, in the School of Education at the University of California at Davis. His research interests include the development of alternative models for university education that are founded on student-centered experiential learning. Specifically, he studies models of permaculture education that lead toward accredited degrees and relates these models to sustainable agriculture degree programs     

Trading water for carbon with biological carbon sequestration

Carbon sequestration strategies highlight tree plantations without considering their full environmental consequences. We combined field research, synthesis of more than 600 observations, and climate and economic modeling to document substantial losses in stream flow, and increased soil salinization and acidification, with afforestation. Plantations decreased stream flow by 227 millimeters per year globally (52%), with 13% of streams drying completely for at least 1 year. Regional modeling of U.S. plantation scenarios suggests that climate feedbacks are unlikely to offset such water losses and could exacerbate them. Plantations can help control groundwater recharge and upwelling but reduce stream flow and salinize and acidify some soils.     

Pigeons on par with primates in numerical competence

Although many animals are able to discriminate stimuli differing in numerosity, only primates are thought to share our ability to employ abstract numerical rules. Here, we show that this ability is present in pigeons and that their performance is indistinguishable from that displayed by monkeys.     

Transformative food systems education in a land-grant college of agriculture: the importance of learner-centered inquiries

In this paper we use a critically reflective research approach to analyze our efforts at transformative learning in food systems education in a land grant university. As a team of learners across the educational hierarchy, we apply scholarly tools to the teaching process and learning outcomes of student-centered inquiries in a food systems course. The course, an interdisciplinary, lower division undergraduate course at the University of California, Davis is part of a new undergraduate major in Sustainable Agriculture and Food Systems. We provide an overview of the course’s core elements—labs, exams, assignments, and lectures—as they relate to social constructivist learning theory and student-centered inquiries. Then, through qualitative analysis of students’ reflective essays about their learning experiences in the course, we demonstrate important transformative outcomes of student-centered inquiries: (1) most students confronted the commodity fetish and tried to reconcile tensions between what the food system is and ought to be, and (2) students repositioned themselves, their thinking, and social deliberation in relation to the food system. Students’ reflections point to the power of learning that emerges through their inquiry process, including in the field, and from critical self-reflection. We also highlight the importance of reflective essays in both reinforcing experiential learning and in helping instructors to better understand students’ learning vis-à-vis our teaching.     

Farmland bird responses to intersecting replanted areas

Despite increasing revegetation of cleared landscapes around the world, there is limited research on the implications of different types of plantings for birdlife. We examined the “intersection effect”, whereby species richness is higher at the intersection of “corridors” or vegetation strips for birds inhabiting replanted areas. We also examined individual species responses. Replicated sites at the intersections of plantings were compared with “internal controls” (located in the same plantings ∼100 m from intersections), “external controls”(sites in isolated linear plantings), and block plantings. We surveyed the 39 sites in our experimental design repeatedly – on different days by different observers and in different seasons. We found no significant difference in species richness between intersections and block plantings, but intersections had higher species richness than isolated linear strips and the internal controls. Similar results were found for bird assemblage scores derived by correspondence analysis. We found evidence of extra-variation at the farm-level for species richness and derived assemblage scores, suggesting a farm-scale response. This suggests the importance of other (often unmeasured) factors at the farm level (e.g. baiting for feral animals). Our results suggest that replanting programs aimed at maximizing bird species richness may benefit from consideration of planting geometry. In particular, linking strip plantings to create intersections and/or establishing block plantings appear to be superior to isolated strips for aggregate species richness.     

Managing invasive plants on public conservation forestlands: Application of a bio-economic model

Public conservation forestlands protect natural resources, provide wildlife habitat, and service a multi-billion dollar recreation industry. Invasive upland plants (IPs) threaten to dramatically reduce the flow of goods and services from these lands. In the late 1990s, a Florida (USA) state program began combating IPs on public conservation lands. By 2007, the program had controlled roughly 1/3 of the 1.5 million IP-infested acres, primarily due to a surge in expenditures that began in 2001 and peaked in 2005. This study evaluates the effectiveness and efficiency of the program by simulating the costs and benefits of IP control through 2016 under five feasible policy alternatives: (I) Do nothing, (II) Maintenance control, (III) 2001–2004 level (of program spending), (IV) 2005 level, and (V) Maximum net present value. To evaluate the policies, we construct a bio-economic model that is parameterized using observations of IP coverage and data from 11 state regions. Given the uncertain nature of IP spread, we simulate the policies' economic impacts under two plausible spread rates. Simulation results indicate that the program's recent efforts are highly effective – generating up to $865.1 million in present value net benefits through 2016 – but less efficient than more costly, front-loaded spending that can generate up to 4.37 times more net benefits.     

Leaf traits in relation to crown development, light interception and growth of elite families of loblolly and slash pine

Crown architecture and size influence leaf area distribution within tree crowns and have large effects on the light environment in forest canopies. The use of selected genotypes in combination with silvicultural treatments that optimize site conditions in forest plantations provide both a challenge and an opportunity to study the biological and environmental determinants of forest growth. We investigated tree growth, crown development and leaf traits of two elite families of loblolly pine (Pinus taeda L.) and one family of slash pine (P. elliottii Mill.) at canopy closure. Two contrasting silvicultural treatments -- repeated fertilization and control of competing vegetation (MI treatment), and a single fertilization and control of competing vegetation treatment (C treatment) -- were applied at two experimental sites in the West Gulf Coastal Plain in Texas and Louisiana. At a common tree size (diameter at breast height), loblolly pine trees had longer and wider crowns, and at the plot-level, intercepted a greater fraction of photosynthetic photon flux than slash pine trees. Leaf-level, light-saturated assimilation rates (A(max)) and both mass- and area-based leaf nitrogen (N) decreased, and specific leaf area (SLA) increased with increasing canopy depth. Leaf-trait gradients were steeper in crowns of loblolly pine trees than of slash pine trees for SLA and leaf N, but not for A(max). There were no species differences in A(max), except in mass-based photosynthesis in upper crowns, but the effect of silvicultural treatment on A(max) differed between sites. Across all crown positions, A(max) was correlated with leaf N, but the relationship differed between sites and treatments. Observed patterns of variation in leaf properties within crowns reflected acclimation to developing light gradients in stands with closing canopies. Tree growth was not directly related to A(max), but there was a strong correlation between tree growth and plot-level light interception in both species. Growth efficiency was unaffected by silvicultural treatment. Thus, when coupled with leaf area and light interception at the crown and canopy levels, A(max) provides insight into family and silvicultural effects on tree growth.     

Genetic analysis of photosynthesis‐related traits in faba bean (Vicia faba) for crop improvement

Increasing productivity through improvement of photosynthesis in faba bean breeding programmes requires understanding of the genetic control of photosynthesis‐related traits. Hence, we investigated the gene action of leaf area, gas exchange traits, canopy temperature, chlorophyll content, chlorophyll fluorescence parameters and biomass. We chose inbred lines derived from cultivars 'Aurora' (Sweden) and 'Mélodie' (France) along with an Andean accession, ILB 938, crossed them (Aurora/2 × Mélodie/2, ILB 938/2 × Aurora/2 and Mélodie/2 × ILB 938/2), and prepared the six standard generations for quantitative analysis (P₁, P₂, F₁, F₂, B₁, and B₂). Gene action was complex for each trait, involving additive and dominance gene actions and interactions. Additive gene action was important for SPAD, photosynthetic rate, stomatal conductance and F_v/F_m. Dominance effect was important for biomass production. It is suggested that breeders selecting for productivity can maximize genetic gain by selecting early generations for canopy temperature, SPAD and F_v/F_m, then later generations for biomass. The information on genetics of various contributing traits of photosynthesis will assist plant breeders in choosing an appropriate breeding strategy for enhancing productivity in faba bean.     

In vitro measurement of volatile release in model lipid emulsions using proton transfer reaction mass spectrometry

The presence of fat in food plays an important role in the way aroma is released during consumption and in the creation of the overall sensory impression. Fat acts as a reservoir for lipophilic volatile compounds and modulates the timing and delivery of aroma compounds in a unique manner. Despite considerable research, reproducible in vitro methods for measuring the effect of fat on volatile release are lacking. An open in vitro cell was used to simulate the open human naso-oropharygeal system and was interfaced with a proton transfer reaction mass spectrometer (PTR-MS) to examine some of the fundamental effects of fat on dynamic volatile release in liquid fat emulsions. Lipid emulsions with various fat contents (0-20%) and droplet sizes (0.25, 0.5, and 5.0 μM) were spiked with flavor volatiles representing a range of lipophilicity (K(o/w) = 1-1380). Preloaded syringes of spiked emulsion were injected into the cell, and temporal changes in release were measured under dynamic conditions. Significant differences in release curves were measured according to the lipid content of emulsions, the vapor pressure, and K(o/w) values of the volatile compounds. With increasing addition of fat, the critical volatile release parameters, maximum concentration (I(max)), time to maximum concentration (T(max)), and the integrated area under the concentration curve (AUC), were affected. The in vitro curves were reproducible and in agreement with theory and correlated with the preswallow phase of in vivo release data. An exponential model was used to calculate changes in mass transfer rates with increased fat addition.