529 research outputs found
Conserving the Genetic Diversity of Domesticated Livestock
No full textDomesticated animals live and produce in an environment influenced by both natural and human factors. These agricultural environments are important to maintain for human survival and also for their interactions with natural environments. Effective conservation of domesticated biodiversity can help to assure sustainable agricultural systems that minimize negative influences on natural environments. In addition, livestock biodiversity is a component of total biodiversity and for several species is the only remaining source of diversity because the wild ancestors are now extinct. Conservation of livestock biodiversity depends on cultural and biological approaches. Each of these has differential importance depending on the specific location of the genetic resource as well as the human culture in which it resides. Effective global conservation blends these in different measures to assure positive outcomes that succeed in securing the genetic resource as well as its contribution to human survival and well-being
Prostaglandins Modulate the Uterine Response to Infectious Bacteria in Postpartum and Estrous Cyclic Ewes
No full textThe uterine immune system is down regulated when exposed to P4. Five experiments were conducted to determine the in vivo and in vitro role(s) of P4 and prostaglandins in immune function(s) associated with uterine infections. In Exp. 1, postpartum ewes (d 0 = parturition) were supplemented with either OIL or P4 (beginning on d 10) or were SHAM or OVEX. Vena caval blood and lymphocytes were collected on d 14, and 16 to 19. All ewes received intrauterine inoculations of bacteria on d 15 and uteri were collected on d 20. Ewes receiving P4 developed infections. Lymphocytes were incubated with mitogens, PGE2, indomethacin (INDO; a PG synthesis inhibitor) or both in a 3 x 2 x 2 arrangement. Concanavalin A-stimulated blastogenesis in P4-OVEX ewes and PGE2 and PGE2+INDO treated lymphocytes was inhibited (P < .05). Cyclic ewes in their follicular or luteal phase received either intrauterine inoculations of saline or bacteria, vena caval blood was collected for 3 d, and uteri were collected. Lymphocytes were incubated with mitogens, PGE2 (Exp. 2), PGF2alpha (Exp. 3) and(or) INDO in a 3 x 2 x 2 arrangement. Only luteal phase ewes that received bacteria developed infections. In Exp. 2, Con A- and LPS-stimulated blastogenesis was greater for luteal than for follicular phase ewes. T lymphocyte proliferation was inhibited in ewes inoculated with bacteria. T lymphocyte proliferation tended to be higher (P = .09) when incubated with INDO. In Exp. 3, T lymphocyte proliferation in response to PGF2alpha was greater for follicular than for luteal phase ewes. Neutrophils were lower in ewes inoculted with bacteria. In Exp. 4 and 5, uteri of luteal-phase (d 6) ewes were inoculated with bacteria. Ewes received either 15 mg of Lutalyse or saline on d 9, and uteri were collected on d 11. Lutalyse reduced P4, tended to decrease neutrophils, allowed ewes to clear infections, and had no effect on blastogenesis. Methods for modulating uterine prostaglandins seem to reduce susceptibility to uterine infections.Ph. D
Engineering strong-field phenomena : from attosecond pulse characterization to nanostructured electron emitters
No full textThesis: Ph. D., Massachusetts Institute of Technology, Department of Electrical Engineering and Computer Science, 2015.This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.Cataloged from student-submitted PDF version of thesis.Includes bibliographical references (pages 141-149).Strong-field phenomena are a driving force behind the latest innovations in ultrafast science. As ultrafast laser sources improve in terms of peak pulse energy and wavelength tunability, applications that utilize high peak electromagnetic field strengths to generate attosecond pulses of both photons and electrons are becoming readily available. Furthermore, through the coupling of these optical fields to nanostructures that further enhance peak field strengths, a new generation of electron emitters and "light-speed" electronics are now emerging. This thesis explores two such areas in detail: the generation and characterization of attosecond pulses of light, and strong-field photoemission from nanostructures.by Phillip D. Keathley.Ph. D
Conservação da pecuária crioula nos Estados Unidos: desafios e soluções
No full textConservation of criollo breeds in the USA provides for the survival of unique genetic resources that remain productive in challenging environments. Conservation is difficult because most criollo breeds are local and have no formal organization of breeders. Successful conservation has depended on establishing accurate breed definitions and investigations of phenotype, history, and genetics. Organization of breeders and of breeding has been essential for the final success of conservation efforts. Each specific breed has met its own unique challenges. Among cattle breeds, Texas Longhorns needed an accurate breed definition as well as genetic investigations, whereas Florida Crackers needed organization. Spanish goats required definition, organization, and research into their productive potential. This has led to the Spanish goat now being secure as a popular choice for extensive production of goat meat. Navajo Churro sheep are maintained by ongoing phenotypic evaluation at each generation and careful attention to the frequency of phenotypic characteristics within the population. The other criollo sheep breeds in the USA (Louisiana, Gulf Coast, and Florida) have benefitted from genetic studies that demonstrate differences among the breeds and guide conservation of each of these related types in isolation one from the others. The organization of criollo swine has lagged behind the others, with the Duroc standing out as an exception that has become one of the main breeds in commercial hog production.La conservación de las razas ganaderas criollas en los EE.UU. ha contribuído a la sobrevivencia de recursos zoogenéticos únicos que tienen buena producción en ambientes duros. La conservación es difícil porque la mayoría de estas razas son locales y no tienen una organización formal de los criadores. El éxito depende en una definición fija para la raza, e investigaciones del fenotipo, la historia, y la genética. Organizar a los criadores y la crianza ha sido esencial en el éxito final de las razas. Cada raza enfrente sus propios desafíos. Entre las razas bovinas el Texas Longhorn necesitó una definición preciso tanto investigaciones de la genética para asegurar niveles bajos de la introgresión de otras razas. La raza bovina Florida Cracker necesitó una organización de los criadores. La raza caprina Spanish requirió definición, organización, e investigaciones de las características productivas. Esta raza ya está seguro por su papel en sistemas productivos en situaciones extensivas. La raza ovina Navajo Churro se mantiene por una evalución fenotípica para todos los animales de toda generaciones, y también por mantener la frecuencia de varias características fenotípicas. Las otras razas criollas ovinas (Louisiana, Gulf Coast, and Florida) fueron documentados como tres poblaciones por investigaciones genéticas que demostraron diferencias entre ellas. Las investigaciones ayudan in la conservación de las tres razas una aislada a las otras. La organización de los porcinos criollos no es muy avanzada. La raza Duroc es un tipo de criollo que ha llegado a tener un papel importante en la producción porcina comercial.A conservação das raças criollas nos EUA proporciona a sobrevivência de recursos genéticos únicos que permanecem produtivos em ambientes desafiadores. A conservação é difícil porque a maioria das raças criollas são locais e não têm uma organização formal de criadores. A conservação bem-sucedida depende do estabelecimento de definições precisas de raça e investigações de fenótipo, história e genética. A organização dos criadores e da criação tem sido essencial para o sucesso final dos esforços de conservação. Cada raça específica encontrou seus próprios desafios únicos. Entre as raças de gado, o Texas Longhorns precisava de uma definição precisa da raça, bem como de investigações genéticas, enquanto o Florida Crackers precisava de organização. As cabras espanholas exigiam definição, organização e pesquisa sobre seu potencial produtivo. Isso fez com que a cabra espanhola agora se tornasse uma escolha popular para a produção extensiva de carne de cabra. Os ovinos Navajo Churro são mantidos por avaliação fenotípica contínua em cada geração e atenção cuidadosa à frequência das características fenotípicas na população. As outras raças de ovinos crioulos nos EUA (Louisiana, Gulf Coast e Flórida) se beneficiaram de estudos genéticos que demonstram diferenças entre as raças e orientam a conservação de cada um desses tipos relacionados isoladamente uns dos outros. A organização da suinocultura crioula ficou atrás das demais, destacando-se o Duroc como uma exceção que se tornou uma das principais raças na produção comercial de suínos
Role of CD44 in Immune Functions and Endothelial Cell Injury
No full textIn addition to the antigen-specific receptors, the T and B cells also express a variety of adhesion molecules, which are known to participate in cell-cell interaction, migration, homing and signal transduction. CD44 is a widely distributed cell surface glycoprotein whose principal ligand has been identified as hyaluronic acid (HA), a major component of the extracellular matrix. In the current study, we investigated whether HA or mAbs against CD44 would induce a proliferative response in mouse lymphocytes. Spleen cells from normal and nude but not severe combined immunodeficient mice, exhibited strong proliferative responsiveness to stimulation with soluble HA or anti-CD44 mAbs. Furthermore, purified B cells but not T cells were found to respond to HA. These data demonstrated that interaction between HA and CD44 can regulate murine B cell effector functions and that such interactions may play a critical role during normal or autoimmune responsiveness of B cells.
Endothelial cell injury resulting in vascular leak syndrome (VLS) is one of the most widely noted phenomenons in a variety of clinical diseases, however, the underlying reason for which remains unclear. We used interleukin-2 induced VLS as a model to investigate the role of cytolytic lymphocytes in the direct cytotoxicity of endothelial cells. BL/6 wild-type mice developed significant VLS in the lungs, liver and spleen following IL-2 administration. Interestingly, perforin-knockout mice exhibited marked decrease in VLS in all three organs tested. Also, FasL-defective (gld) mice and Fas-deficient (lpr) mice exhibited decreased VLS in the liver and spleen, but not in the lungs. These results demonstrated for the first time that perforin and FasL may actively participate in endothelial cell injury and induction of VLS in a variety of organs.
Inasmuch as, CD44 also plays a major role in the lymphocyte adhesion to the endothelial cells, we used CD44-knockout mice and observed that such mice exhibited markedly diminished VLS following IL-2-treatment. Our data also suggested that blocking CD44 helps in reducing the IL-2-induced VLS and therefore such an approach may serve as a useful tool to prevent endothelial cell damage seen in a variety of clinical disorders.Ph. D
A possible dominant white gene in Jersey cattle
Get PDFAbstract A white heifer ("Snow") was born in 1991 from coloured registered Jersey parents. She produced six calves sired by coloured Jersey bulls: three white bull calves, two white heifer calves, and one coloured bull calf. One of the white bull calves was mated with 40 Hereford × Friesian yearling heifers (white face, predominantly black body with some white patches). The 38 resulting calves included 16 white and 22 coloured calves. Twelve of the 16 white calves were heifers and four were bulls. Red or black spotting was recorded on some white calves. The results are consistent with an autosomal dominant mutant causing the white phenotype. The mutation appears to have arisen spontaneously in Snow, then passing to her white progeny and white grand-progeny. The white individuals varied from entirely white in a few cases, to most having some residual small areas of red or black pigmentation in patterns not typical of other reported white spotting patterns of cattle.</p
Genetic variation of susceptibility to fescue toxicosis in cattle
No full textFifteen calves of two sires were fed endophyte infected (E + ) fescue seed to quantify differences in susceptibility to fescue toxicosis among sire groups. One of the sires, a Polled Hereford, had a commercial reputation of producing calves with less severe symptoms of tall fescue toxicosis than their contemporaries. The control sire, also a Polled Hereford, had unknown merit with regard to offspring susceptibility to fescue toxicosis. The study was divided into five phases, two in which endophyte-infected fescue seed was included in the diet (phases two and four) and three in which fescue seed was not in the diet (phases one, three, and five). All calves were treated similarly and given the same opportunities for water, shade and socialization. Susceptibility to fescue toxicosis was measured by appetite (amount of feed consumed per day per unit of metabolic body weight), serum prolactin, cholesterol, and alkaline phosphatase concentrations, ability to maintain homeotherny (afternoon minus morning rectal temperature), ability to dissipate core body heat (afternoon minus morning surface temperature), and heat-transfer inefficiency (afternoon rectal minus afternoon surface temperatures). Appetite was decreased by the E + fescue seed, but the sire groups did not differ in their response to or recovery from E + fescue seed. The E + fescue seed caused prolactin to decrease (P < .0001) but the sire groups did not differ in their responses to addition or withdrawal of E + fescue seed from the diet. Cholesterol levels were lower overall (P < .001) when the E+ fescue seed was fed, and the sire groups recovered from the fescue toxicity at different rates (P < .001). Alkaline phosphatase concentrations were lower during the phases when E + fescue seed was fed; calves from the control sire were less resistant to the E + fescue seed effects than the Missouri calves (P < .0001). Ability to maintain homeothermy was reduced by the E + fescue seed, but the reduction did not differ between sire groups. Surface temperature changes and heat-transfer inefficiencies were not indicative of fescue toxicosis in this study. It was concluded that serum cholesterol and serum alkaline phosphatase concentrations may be accurate indicators of differences among paternal half sib groups of cattle in susceptibility to fescue toxicosis.Master of Scienc
Evaluation of the Normal Equine Pituitary Gland
No full textComputed tomography (CT) is becoming more available as a diagnostic tool in the evaluation of the equine skull and brain. Objectives of this study were: 1) refine a CT protocol for evaluating the equine pituitary gland, 2.) define the CT anatomy of the pituitary region, 3.) determine a set of normal values for the pituitary dimensions (length, width, height, volume and weight), 4.) refine CT techniques for measuring pituitary size.
Horses were scanned using 10x10mm, 10x5mm, 4x4mm and 4x2mm slice thickness and interval combinations. The pituitary glands were removed immediately after CT and gross measurements were performed. CT measurements were compared with gross pituitary measurements using analysis of variance (ANOVA) in a randomized block design. Accuracy percentages were also calculated using gross measurements as the known value.
Mean dimensions of the histologically normal pituitary glands were: length 21.07mm, width 21.62mm, height 9.78mm and volume 2.66cm³. The weights ranged from 1.7g to 3.4g with a mean of 2.6g. Computed tomographic measurement analysis demonstrated that the 10mm slices were the most accurate way to estimate the length of the gland. The 4mm slices yielded the highest accuracy values for width, height and volume of the pituitary gland. The volume was underestimated by all interval and slice thickness combinations performed by CT. No evidence of an overlap effect was identified for any of the dimensions.
Our findings indicated that contrast-enhanced CT is an accurate technique for estimating pituitary linear dimensions. Three-dimensional CT volumetry may not be an accurate method for estimating pituitary volume.Master of Scienc
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