Life Sciences Commons^™

Utilizing Markov Chains To Estimate Allele Progression Through Generations, Ronit Gandhi

Honors Theses

All populations display patterns in allele frequencies over time. Some alleles cease to exist, while some grow to become the norm. These frequencies can shift or stay constant based on the conditions the population lives in. If in Hardy-Weinberg equilibrium, the allele frequencies stay constant. Most populations, however, have bias from environmental factors, sexual preferences, other organisms, etc. We propose a stochastic Markov chain model to study allele progression across generations. In such a model, the allele frequencies in the next generation depend only on the frequencies in the current one.

We use this model to track a recessive allele …

Genomic Tools Reveal Complex Social Organization Of An Invasive Large Mammal (Sus Scrofa), Chelsea L. Titus, Courtney F. Bowden, Timothy J. Smyser, Stephen L. Webb, James C. Beasley

USDA Wildlife Services: Staff Publications

A comprehensive understanding of sociality in wildlife is vital to optimizing conservation and management efforts. However, sociality is complicated, especially for widely distributed species that exhibit substantive behavioral plasticity. Invasive wild pigs (Sus scrofa), often representing hybrids of European wild boar and domestic pigs, are among the most adaptable and widely distributed large mammals. The social structure of wild pigs is believed to be similar to European wild boar, consisting of matriarchal groups (sounders) and solitary males. However, wild pig social structure is understudied and largely limited to visual observations. Using a hierarchical approach, we incorporated genomic tools …

Climate And Agronomy, Not Genetics, Underpin Recent Maize Yield Gains In Favorable Environments, Gonzalo Rizzo, Juan Pablo Monzon, Fatima Amor Tenorio, Réka Howard, Kenneth G. Cassman, Patricio Grassini

Department of Agronomy and Horticulture: Faculty Publications

Quantitative understanding of factors driving yield increases of major food crops is essential for effective prioritization of research and development. Yet previous estimates had limitations in distinguishing among contributing factors such as changing climate and new agronomic and genetic technologies. Here, we distinguished the separate contribution of these factors to yield advance using an extensive database collected from the largest irrigated maize-production domain in the world located in Nebraska (United States) during the 2005-to-2018 period. We found that 48% of the yield gain was associated with a decadal climate trend, 39% with agronomic improvements, and, by difference, only 13% with …

Meat Tenderness: Advances In Biology, Biochemistry, Molecular Mechanisms And New Technologies, Robyn D. Warner, Tommy L. Wheeler, Minh Ha, Xin Li, Alaa El-Din Bekhit, James Morton, Rozita Vaskoska, Frank R. Dunshea, Rui Lui, Peter Purslow, Wangang Zhang

Roman L. Hruska U.S. Meat Animal Research Center: Reports

Meat tenderness is an important quality trait critical to consumer acceptance, and determines satisfaction, repeat purchase and willingness-to-pay premium prices. Recent advances in tenderness research from a variety of perspectives are presented. Our understanding of molecular factors influencing tenderization are discussed in relation to glycolysis, calcium release, protease activation, apoptosis and heat shock proteins, the use of proteomic analysis for monitoring changes, proteomic biomarkers and oxidative/nitrosative stress. Each of these structural, metabolic and molecular determinants of meat tenderness are then discussed in greater detail in relation to animal variation, postmortem influences, and changes during cooking, with a focus on recent …

The Ovarian Follicle Of Ruminants: The Path From Conceptus To Adult, Jennifer L. Juengel, Robert A. Cushman, Joëlle Dupont, Stéphane Fabre, Richard G. Lea, Graeme B. Martin, Francesca Mossa, Janet L. Pitman, Christopher A. Price, Peter Smith

Roman L. Hruska U.S. Meat Animal Research Center: Reports

This review resulted from an international workshop and presents a consensus view of critical advances over the past decade in our understanding of follicle function in ruminants. The major concepts covered include: (1) the value of major genes; (2) the dynamics of fetal ovarian development and its sensitivity to nutritional and environmental influences; (3) the concept of an ovarian follicle reserve, aligned with the rise of anti-Müllerian hormone as a controller of ovarian processes; (4) renewed recognition of the diverse and important roles of theca cells; (5) the importance of follicular fluid as a microenvironment that determines oocyte quality; (6) …

Review: Perspective On High-Performing Dairy Cows And Herds, J. H. Britt, R. A. Cushman, C. D. Dechow, H. Dobson, P. Humblot, M. F. Hutjens, G. A. Jones, F. M. Mitloehner, P. L. Ruegg, I. M. Sheldon, J. S. Stevenson

Roman L. Hruska U.S. Meat Animal Research Center: Reports

Milk and dairy products provide highly sustainable concentrations of essential amino acids and other required nutrients for humans; however, amount of milk currently produced per dairy cow globally is inadequate to meet future needs. Higher performing dairy cows and herds produce more milk with less environmental impact per kg than lower performing cows and herds. In 2018, 15.4% of the world's dairy cows produced 45.4% of the world's dairy cow milk, reflecting the global contribution of high-performing cows and herds. In high-performing herds, genomic evaluations are utilized for multiple trait selection, welfare is monitored by remote sensing, rations are formulated …

Evolutionary And Ecological Determinism Of Host Specificity In Arthropod Parasites, Joseph Levey

UCARE Research Products

Understanding why some diseases infect more species than others is crucial for predicting where and when disease will spread, which can inform the management of wildlife, agriculture, and human health. Currently, large scale patterns of host-parasite dynamics are being studied to understand where to look for and how to manage emerging human diseases (Leroy 2005; Benelli 2018). Previous research has used the Global Mammal Parasite Database (GMPD) to look at host breadth—the number and diversity of species a pathogen can infect—for various groups of parasites, e.g. helminths, arthropods, fungi, etc., from a host-centric perspective (Stephens et al. 2017; Park et …

Genetic Studies Of Wildlife, Brittaney L. Buchanan

School of Natural Resources: Dissertations, Theses, and Student Research

Genetic techniques are being more frequently used to understand the biology and management of wildlife species. The wild turkey is one species of genetic interest because the correct identification of individuals to the subspecies level is difficult using traditional methods. Currently phenotypic differences in plumage, especially the upper tail coverts, are used to assign individuals to subspecies. To hunters wanting to complete a “grand slam,” identification of birds’ subspecies is important. This study focuses on the five extant subspecies: Eastern (M. g. silvestris), Osceola (M. g. osceola), Rio Grande (M. g. intermedia), Merriam’s ( …

Detection Of Heteroplasmic Single Nucleotide Polymorphisms Using Melt Curve Analysis And Dual Labeled Fluorescent Probes, Emily Jezewski

Honors Theses

Plant mitochondrial genomes are strange – they are unusually large, consist of huge amounts of non-coding DNA, and contain of several overlapping regions throughout the genome. The genome is made of several different sized linear and circular molecules and different mitochondria within a cell will have different pieces of the genome. Even if multiple mitochondria contain the same region of the genome, these sequences can differ by single nucleotide polymorphisms (SNPS). This is known as heteroplasmy. Heteroplasmy has been documented in Arabidopsis thaliana using whole-genome sequencing data. While heteroplasmy is well-documented, its existence in the mitochondrial genome is unexpected and …

Plant Mitochondrial Genome Evolution And Structure Has Been Shaped By Double-Strand Break Repair And Recombination, Emily Wynn

School of Biological Sciences: Dissertations, Theses, and Student Research

Plant mitochondrial genomes are large but contain a small number of genes. These genes have very low mutation rates, but genomes rearrange and expand at significant rates. We propose that much of the apparent complexity of plant mitochondrial genomes can be explained by the interactions of double-strand break repair, recombination, and selection. One possible explanation for the disparity between the low mutation rates of genes and the high divergence of non-genes is that synonymous mutations in genes are not truly neutral. In some species, rps14 has been duplicated in the nucleus, allowing the mitochondrial copy to become a pseudogene. By …

Genome-Wide Characterization, Molecular Evolution And Mexpression Profiling Of The Metacaspases In Potato (Solanum Tuberosum L.), Nehal Dubey, Maitri Trivedi, Suresh Varsani, Vishal Vyas, Manisha Farsodia, Sunil Kumar Singh

Department of Entomology: Faculty Publications

Metacaspases are distant relatives of animal caspases found in plants, protozoa and fungi. Some recent studies have demonstrated that metacaspases are involved in regulating the developmental and environmentally induced programmed cell death in plants. In this study, we identified metacaspase gene family in potato (Solanum tuberosum L.) and analyzed their expression pattern in various developmental tissues and stress responses of plants. There were eight metacaspase genes identified in the Peptidase (Cysteine protease) C14 family and based upon sequence alignment and phylogenetic analysis, a systematic nomenclature of potato metacaspases (SotubMCs) has been proposed. Three of the eight candidate genes showing homology …

A Systematic Review Of Genetic Influence On Psychological Resilience, Kosuke Niitsu, Michael J. Rice, Julia F. Houfek, Scott F. Stoltenberg, Kevin A. Kupzyk, Cecilia R. Barron

Department of Psychology: Faculty Publications

When exposed to adversity, some individuals are at an increased risk of posttraumatic stress disorder, experiencing persistent biopsychosocial disturbances, whereas others adapt well, described as resilience. Resilience is a complex biopsychosocial phenomenon conceptualized as adaptation to adversity influenced by an individual’s genetic variants, epistasis, epigenetics, and gene-by-environment interactions. Studies on psychological resilience have focused on behavioral and psychosocial variables with far less examination of the genetic contributions. The purpose of this review is to identify specific genetic variants contributing to the biological capacity for psychological resilience. PubMed and PsycINFO were searched using the following key words: psychological resilience AND genotype …

Utilizing Random Regression Models For Genomic Prediction Of A Longitudinal Trait Derived From High‐Throughput Phenotyping, Malachy T. Campbell, Harkamal Walia, Gota Morota

Department of Agronomy and Horticulture: Faculty Publications

The accessibility of high‐throughput phenotyping platforms in both the greenhouse and field, as well as the relatively low cost of unmanned aerial vehicles, has provided researchers with an effective means to characterize large populations throughout the growing season. These longitudinal phenotypes can provide important insight into plant development and responses to the environment. Despite the growing use of these new phenotyping approaches in plant breeding, the use of genomic prediction models for longitudinal phenotypes is limited in major crop species. The objective of this study was to demonstrate the utility of random regression (RR) models using Legendre polynomials for genomic …

Genetic Diversity And Distinctness Of Wild Nebraska Hops And Hop Cultivars (Humulus Lupulus L.), Megan Franklin

Honors Theses

Background Commercial hop (Humulus lupulus) cultivars that are being grown in the Midwest are not performing as successfully as when they are grown in the Pacific Northwest, the region to which they are adapted. To increase adaptation to the Midwest environment, one strategy is to draw from the genetic pool of wild native Midwest hops, which have developed genes that allow them to grow successfully in this environment. Wild hop plants that are genetically distinct from commercial cultivars are likely to have more adaptations, such as pest/disease resistance and drought tolerance, which can be bred into commercial lines. The …

Metabolic Investigations Of The Molecular Mechanisms Associated With Parkinson’S Disease, Robert Powers, Shulei Lei, Annadurai Anandhan, Darrell D. Marshall, Bradley Worley, Ronald Cerny, Eric D. Dodds, Yuting Huang, Mihalis I. Panayiotidis, Aglaia Pappa, Rodrigo Franco

Robert Powers Publications

Parkinson’s disease (PD) is a neurodegenerative disorder characterized by fibrillar cytoplasmic aggregates of α-synuclein (i.e., Lewy bodies) and the associated loss of dopaminergic cells in the substantia nigra. Mutations in genes such as α -synuclein (SNCA) account for only 10% of PD occurrences. Exposure to environmental toxicants including pesticides and metals (e.g., paraquat (PQ) and manganese (Mn)) is also recognized as an important PD risk factor. Thus, aging, genetic alterations, and environmental factors all contribute to the etiology of PD. In fact, both genetic and environmental factors are thought to interact in the promotion of idiopathic PD, but the mechanisms …

Bois 412/812: Human Genetics—A Peer Review Of Teaching Project Benchmark Portfolio, Colin D. Meiklejohn

UNL Faculty Course Portfolios

This portfolio focuses on Human Genetics, an upper-division course taken primarily by biology majors to fulfill elective credit in their degree. This course studies the genetic basis for human variation, with the goal of placing this variation in the context of human evolutionary history and the consequences of this variation for medical understanding and treatments. In Human Genetics, students complete an original synthetic research paper on a human genetic disorder. Through writing this paper, students are expected to learn how to navigate electronic databases and online resources on human genetic diseases, and to read and synthesize the primary scientific literature. …

Exceptionally High Levels Of Genetic Diversity In Wheat Curl Mite (Acari: Eriophyidae) Populations From Turkey, W. Szydło, Gary L. Hein, E. Denizhan, A. Skoracka

Department of Entomology: Faculty Publications

Recent research on the wheat curl mite species complex has revealed extensive genetic diversity that has distinguished several genetic lineages infesting bread wheat (Triticum aestivum L.) and other cereals worldwide. Turkey is the historical region of wheat and barley (Hordeum vulgare L.) domestication and diversification. The close relationship between these grasses and the wheat curl mite provoked the question of the genetic diversity of the wheat curl mite in this region. The scope of the study was to investigate genetic differentiation within the wheat curl mite species complex on grasses in Turkey. Twenty-one wheat curl mite populations from …

Estimation Of Breed-Specific Heterosis Effects For Birth, Weaning, And Yearling Weight In Cattle, Lauren N. Schiermiester, R. M. Thallman, Larry Kuehn, Stephen D. Kachman, Matthew L. Spangler

Department of Animal Science: Faculty Publications

Heterosis, assumed proportional to expected breed heterozygosity, was calculated for 6834 individuals with birth, weaning and yearling weight records from Cycle VII and advanced generations of the U.S. Meat Animal Research Center (USMARC) Germplasm Evaluation (GPE) project. Breeds represented in these data included: Angus, Hereford, Red Angus, Charolais, Gelbvieh, Simmental, Limousin and Composite MARC III. Heterosis was further estimated by proportions of British × British (B × B), British × Continental (B × C) and Continental × Continental (C × C) crosses and by breed-specific combinations. Model 1 fitted fixed covariates for heterosis within biological types while Model 2 fitted …

Managing Hybridization Of A Recovering Endangered Species: The Red Wolf Canis Rufus As A Case Study, Eric M. Gese, Fred F. Knowlton, Jennifer R. Adams, Karen Beck, Todd K. Fuller, Dennis L. Murray, Todd D. Steury, Michael K. Stoskopf, Will T. Waddell, Lisette P. Waits

USDA Wildlife Services: Staff Publications

Hybridization presents a unique challenge for conservation biologists and managers. While hybridization is an important evolutionary process, hybridization is also a threat formany native species. The endangered species recovery effort for the red wolf Canis rufus is a classic system for understanding and addressing the challenges of hybridization. From 1987‒1993, 63 red wolves were released from captivity in eastern North Carolina, USA, to establish a free-ranging, non-essential experimental population. By 1999, managers recognized hybridization with invasive coyotes Canis latrans was the single greatest threat to successful recovery, and an adaptive management plan was adopted with innovative approaches for managing the …

Genome-Wide Prediction Of Age At Puberty And Reproductive Longevity In Sows, Julie Kathleen Tart, Rodger K. Johnson, Justin W. Bundy, N. N. Ferdinand, A. M. Mcknite, Jennifer R. Wood, Phillip S. Miller, M. F. Rothschild, Matthew L. Spangler, Dorian J. Garrick, Stephen D. Kachman, Daniel C. Ciobanu

Department of Animal Science: Faculty Publications

Traditional selection for sow reproductive longevity is ineffective due to low heritability and late expression of the trait. Incorporation of DNA markers into selection programs is potentially a more practical approach for improving sow lifetime productivity. Using a resource population of crossbred gilts, we explored pleiotropic sources of variation that influence age at puberty and reproductive longevity. Of the traits recorded before breeding, only age at puberty significantly affected the probability that females would produce a first parity litter. The genetic variance explained by 1-Mb windows of the sow genome, compared across traits, uncovered regions that influence both age at …

Dirofilariosis In The Americas: A More Virulent Dirofilaria Immitis?, Filipe Dantas-Torres, Domenico Otranto

Harold W. Manter Laboratory: Library Materials

Dirofilarioses are widespread diseases caused by filarioid nematodes (superfamily Filarioidea) of the genus Dirofilaria, which are transmitted by a plethora of mosquito species. The principal agent of canine dirofilariosis in the Americas is Dirofilaria immitis, which may also occasionally infest humans, resulting in pulmonary nodules that may be confounded with malignant lung tumours. Because human cases of dirofilariosis by D. immitis are relatively frequent in the Americas and rare in Europe and other eastern countries, where Dirofilaria repens is the main causative agent, the existence of a more virulent strain of D. immitis in the Americas …

The Evolution Of Host Specificity In The Vertebrate Gut Symbiont Lactobacillus Reuteri, Steven Frese

Department of Food Science and Technology: Dissertations, Theses, and Student Research

The vertebrate gut is home to one of the densest populations of life on Earth. This microbial community has a profound effect on host health, nutrition, development, behavior, and evolution. However, very little is known about how these microbes have evolved with their vertebrate hosts, how and whether they select hosts or how they remain associated with their hosts. Recent work identified Lactobacillus reuteri as an organism that is composed of host-specific sub-populations, each population associated with a different host animal. Representatives from each host-associated population were tested for their ability to colonize gnotobiotic mice, which only rodent strains could …

Genetic Measures Confirm Familial Relationships And Strengthen Study Design, Stacie J. Robinson, Ryan D. Walrath, Timonthy R. Vandeelen, Kurt C. Vercauteren

USDA Wildlife Services: Staff Publications

Social structure and behavioral interactions between individuals shape basic biological processes, such as breeding; foraging and predator avoidance; movement and dispersal; and disease transmission. We used a targeted trapping strategy to capture kin groups of white-tailed deer (Odocoileus virginianus) during 2007 and 2008 in Sandhill Wildlife Research Area, Wisconsin, USA, in order to observe social behaviors. Because inferring family relationships from observation of behavior is subjective, we usedmeasures of genetic relatedness and parentage assignment tests to determine that our capture strategy was efficient for capturing related pairs (78% of groups contained 1 dyad of related animals). The results of …

Genetic Variation And Inheritance Of Diapause Induction In Two Distinct Voltine Ecotypes Of Ostrinia Nubilalis (Lepidoptera: Crambidae), Cengis Ikten, Steven R. Skoda, Thomas E. Hunt, Jaime Molina-Ochoa, John E. Foster

Department of Entomology: Faculty Publications

European corn borer, Ostrinia nubilalis (Hübner) (Lepidoptera: Crambidae), displays a larval diapause in response to short photoperiods and is adapted to a variety of local conditions throughout North America. Hence, the effective photoperiod inducing larval diapause will differ among geographic ecotypes. This study considers the inheritance of photoperiodic larval diapause induction by hybridization and backcrossing two latitudinally distinct ecotypes of the European corn borer collected between 41° N, 96° W and 48° N, 96° W and under a range of photoperiods representative of their respective locations: from 14:10 to 16:8 (L:D) h. The ecotype adapted to a bivoltine habitat (southeastern …

The Scientific Classification Of Wolves: Canis Lupus Soupus, L. David Mech

USGS Northern Prairie Wildlife Research Center

Gray wolf, timber wolf, red wolf, eastern wolf, brush wolf, arctic wolf, Mexican wolf, maned wolf, Ethiopian wolf, etc., etc. How many kinds of wolves are there? And what are the differences? This is a really good question, and the answer is getting more complicated all the time. Let us start by going back a few years to the way science looked at wolves more traditionally— before the days of the new field of molecular genetics. Molecular genetics examines the actual DNA of animals and tries to classify them according to genetic similarities. ...

What does all this mean in …

Structuring An Efficient Organic Wheat Breeding Program, P. Stephen Baenziger, Ibrahim Salah, Richard S. Little, Dipak K. Santra, Teshome Regassa, Meng Yuan Wang

Department of Agronomy and Horticulture: Faculty Publications

Our long-term goal is to develop wheat cultivars that will improve the profitability and competitiveness of organic producers in Nebraska and the Northern Great Plains. Our approach is to select in early generations for highly heritable traits that are needed for both organic and conventional production (another breeding goal), followed by a targeted organic breeding effort with testing at two organic locations (each in a different ecological region) beginning with the F₆ generation. Yield analyses from replicated trials at two organic breeding sites and 7 conventional breeding sites from F₆ through F₁₂ nurseries revealed, using analyses of …

Microsatellites Reveal Genetic Diversity In Rotylenchulus Reniformis Populations, R. S. Arias, Salliana R. Stetina, Jennifer L. Tonos, Jodi A. Scheffler, Brian E. Scheffler

United States Department of Agriculture-Agricultural Research Service / University of Nebraska-Lincoln: Faculty Publications

Rotylenchulus reniformis is the predominant parasitic nematode of cotton in the Mid South area of the United States. Although variable levels of infection and morphological differences have been reported for this nematode, genetic variability has been more elusive. We developed microsatellite-enriched libraries for R. reniformis, produced 1152 clones, assembled 694 corstigs, detected 783 simple sequence repeats (SSR) and designed 192 SSR-markers. The markers were tested on six R. reniformis cultures from four states, Texas, Louisiana, Mississippi and Georgia, in the USA. Based oil performance we selected 156 SSR markers for R. reniformis from which 88 were polymorphic across the …

2008 Nebraska Beef Cattle Report Summaries, Richard J. Rasby, Galen E. Erickson, Dennis R. Brink

University of Nebraska-Lincoln Extension: Historical Materials

Reports on recent beef research are briefly summarized in this publication. Summaries of the research featured in the 2008 Beef Report appear here. Topics include cow-calf, growing, finishing and beef products.

Contributions To The Chiroptera Of Mongolia With First Evidences On Species Communities And Ecological Niches, Dietrich Dolch, Nyamsuren Batsaikhan, Klaus Thiele, Frank Burger, Ingo Scheffler, Andreas Kiefer, Frieder Mayer, Ravčigijn Samjaa, Annegret Stubbe, Michael Stubbe, Leonard Krall, Dirk Steinhauser

Erforschung biologischer Ressourcen der Mongolei / Exploration into the Biological Resources of Mongolia, ISSN 0440-1298

In this paper are presented the accounts of 13 identified bat species from a total of 628 captured specimens from 32 locations in Mongolia during three field expeditions. These species accounts include taxonomical, morphological, and ecological data resulting from observations and further analyses. As a result of this work the distribution of some bat species in Mongolia can be drawn in more detail. For instance, Vespertilio murinus is much wider distributed and abundant than the former records indicate. The Plecotus species were clearly identified by genetic analyses combined with morphological characteristics. Moreover, the second record for Eptesicus serotinus and the …

When Reintroductions Are Augmentations: The Genetic Legacy Of Fishers (Martes Pennanti) In Montana, Ray S. Vinkey, Michael K. Schwartz, Kevin S. Mckelvey, Kerry R. Foresman, Kristine L. Pilgrim, Brian J. Giddings, Eric C. Lofroth

USDA Forest Service / UNL Faculty Publications

Fishers (Martes pennanti) were purportedly extirpated from Montana by 1930 and extant populations are assumed to be descended from translocated fishers. To determine the lineage of fisher populations, we sequenced 2 regions of the mitochondrial DNA genome from 207 tissue samples from British Columbia, Minnesota, Wisconsin, and Montana. In northwestern Montana, fishers share haplotypes with samples from the upper Midwest and British Columbia; in west-central Montana, we detected haplotypes found in British Columbia samples, but also detected a control region and cytochrome-b haplotype not found in source populations. Based on the unique haplotypes found in west-central Montana, …