College of Agriculture & Natural Resources
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The collections in this community comprise faculty research works, as well as graduate theses and dissertations.
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Item Synergistic Activation of Bovine CD4+ T Cells by Neutrophils and IL-12(MDPI, 2021-06-03) Xiao, Zhengguo; Kandel, Anmol; Li, LeiCD4+ T cell activation requires inflammatory cytokines to provide a third signal (3SI), such as interleukin-12 (IL-12). We recently reported that bovine neutrophils can enhance the activation of bovine CD4+ T cells. To explore the interactions between neutrophils and third signal cytokines in bovine CD4+ T cell activation, naïve CD4+ T cells were isolated from cattle lymph nodes and stimulated for 3.5 days with anti-bovine CD3 (first signal; 1SI), anti-bovine CD28 (second signal; 2SI), and recombinant human IL-12 (3SI) in the presence or absence of neutrophils harvested from the same animals. Indeed, the strongest activation was achieved in the presence of all three signals, as demonstrated by CD25 upregulation, IFNγ production in CD4+ T cells, and secretion of IFNγ and IL-2 in cell supernatants. More importantly, 1SI plus neutrophils led to enhanced CD25 expression that was further increased by IL-12, suggesting synergistic action by IL-12 and neutrophils. Consistently, neutrophils significantly increased IFNγ production in 1SI plus IL-12-stimulated CD4+ T cells. Our data suggest the synergy of neutrophils and IL-12 as a novel regulator on bovine CD4+ T cell activation in addition to three signals. This knowledge could assist the development of immune interventions for the control of infectious diseases in cattle.Item Insights from Initial Variant Detection by Sequencing Single Sperm in Cattle(MDPI, 2021-11-15) Yang, Liu; Gao, Yahui; Boschiero, Clarissa; Li, Li; Zhang, Hongping; Ma, Li; Liu, George E.Meiotic de novo mutation (DNM) is one of the important phenomena contributing to gamete genome diversity. However, except for humans and a few model organisms, they are not well studied in livestock, including cattle. Moreover, bulk sperm samples have been routinely utilized in experiments, which include millions of single sperm cells and only report high-frequency variants. In this study, we isolated and sequenced 143 single sperms from two Holstein bulls and identified hundreds of candidate DNM events in ten sperms with deep sequencing coverage. We estimated DNM rates ranging from 1.08 × 10−8 to 3.78 × 10−8 per nucleotide per generation. We further validated 12 out of 14 selected DNM events using Sanger sequencing. To our knowledge, this is the first single sperm whole-genome sequencing effort in livestock, which provided useful information for future studies of point mutations and male fertility. Our preliminary results pointed out future research directions and highlighted the importance of uniform whole genome amplification, deep sequence coverage, and dedicated software pipelines for genetic variant detection using single-cell sequencing data.Item Differential Expression of CD45RO and CD45RA in Bovine T Cells(MDPI, 2022-06-04) Kandel, Anmol; Li, Lei; Hada, Akanksha; Xiao, ZhengguoEffective vaccination induces immune memory to protect animals upon pathogen re-encounter. Despite contradictory reports, bovine memory T cells are identified based on two isoforms of CD45, expression of CD45RO plus exclusion of CD45RA. In this report, we contrasted CD45RA/RO expression on circulatory T cells with IFNγ and IL4 expression induced by a conventional method. To our surprise, 20% of cattle from an enclosed herd did not express CD45RO on T cells without any significant difference on CD45RA expression and IFNγ or IL4 induction. In CD45RO expressing cattle, CD45RA and CD45RO expressions excluded each other, with dominant CD45RO (>90%) expression on gamma delta (γδ) followed by CD4+ (60%) but significantly higher CD45RA expression on CD8+ T cells (about 80%). Importantly, more than 80% of CD45RO expressing CD4+ and CD8+ T cells failed to produce IFNγ and IL-4; however, within the cytokine inducing cells, CD4+ T cells highly expressed CD45RO but those within CD8+ T cells mostly expressed CD45RA. Hence, CD45RO is not ubiquitously expressed in cattle, and rather than with memory phenotype, CD45RA/RO expression are more associated with distinct T cell subtypes.Item In Vitro Study of an Orange Oil Derived Alternative to Antibiotics in the Treatment of Bovine Mastitis(2015) Federman, Cassandra Skye; Biswas, Debabrata; Animal Sciences; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Bovine mastitis is a costly disease in the U.S. dairy industry. Its major causative agent Staphylococcus aureus is often unresponsive to antibiotic therapy. Our first study examined terpeneless, cold-pressed Valencia (CPV) orange oil as a possible alternative to antibiotic therapy in the treatment of S. aureus associated bovine mastitis. Orange oil showed significant inhibition of S. aureus growth and invasion of bovine epithelial mammary cells, but only modest reductions in pre-formed biofilms, which contribute to persistence of S. aureus infections. Our second study examined major components of terpeneless, CPV orange oil. Of four major compounds tested, only citral and linalool had significant inhibitory effects on S. aureus growth. In addition, they were capable of reducing pre-formed biofilms as well as association and invasion to bovine epithelial mammary cells. Part of this inhibition was due to downregulation of virulence and biofilm genes.Item Maternal Investment in Domestic Cattle(2005-04-18) Moore-Crawford, Cassandra Marie; Stricklin, William R; Animal Sciences; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Hypotheses from biology propose that females that are in better condition are better able to provide resources to their offspring through maternal investment. The investment can be either direct nutritional or greater behavioral investment. The objectives of these studies were to determine the influence of several maternal factors on differential maternal investment. In the first study, data sets were taken from the beef records from the Wye Angus cattle at the University of Maryland Wye Research and Education Center, Queenstown, Maryland and Grazinglands Research Laboratory west of El Reno, Oklahoma. The relationship between age of dam and gestation traits were analyzed based on calf sex for each data set. Two of six maternal traits were significant predictors of calf sex. For the second study, data from the Animal Improvement Programs Laboratory (AIPL) of the USDA, which conducts a national evaluation of birthing difficulty (calving ease), were used. Over 12.4 million dairy records were included in an analysis of sex ratio as a function of parity. Cow productivity influenced future sex ratios. The data support the contention that females in better condition produce male offspring and also indicate that domestic animals, in this case cattle, still exhibit genetic influences that result from evolutionary influences - even though artificial selection influences have occurred. The determination of what mechanisms actually underlie the differential sex ratios that result from females of different production capabilities is an important question that needs further consideration. In the third study, feed competitions between a mother, daughter, and non-related cow were conducted to determine the level of maternal investment after a prolonged separation of mother and daughter. Mothers ate for a significantly greater percentage of the total eating time than either daughter or non-related cows. On the second day of the trials there was a non significant trend for the occurrence of mother-daughter alliances. These results indicate that post weaning associations between mothers and daughters may be disrupted by management practices. The Trivers-Willard hypothesis was supported in dairy cattle, but the beef cattle data only provided limited support for this hypothesis.