Colchicine-Induced Variation in Saintpaulia Propagated in Vitro

Variability is the basis of all crop improvement and breeding programs. There are many difficulties encountered when using a traditional breeding system. First, there is a limited source of new variations. Since spontaneous mutations occur infrequently in most species sources of variation are restricted to the discovery of new genotypes and the genetic combinations produced through breeding programs. Secondly, sexual systems can be difficult to manipulate. There are· environmental problems, incompatible time of anthesis, and internal problems with pollination, fertilization, or embryo development. If a crop improvement system which does not involve sexual structures is chosen new genetic combinations are limited and difficult to obtain. Finally, these systems are often very time-consuming. After selecting a new variant, years of crossing and backcrossing may be required before achieving the desired genotype. Mutation breeding, inducing mutations using chemical, radiation, or physical means could be a new source of variability. Mutation breeding works well with vegetatively propagated plants. Because of their normally heterozygous nature, mutations, whether spontaneous or induced, are commonly exhibited in the treated individual. Since Saintpaulia (African violet) shoots appear to develop from one cell, or occasionally from a few cells, an in vitro mutation system could potentially produce large numbers of nonchimeric mutants. In three months Bilkey and Hildebrandt obtained as many as 20,000 plantlets from one leaf cutting using tissue culture. Using traditional leaf cuttings commonly only five or six plants are produced. Not only is there the potential for increased shoot production and increased variability but African violets could be propagated with increased cost efficiency. In conjunction with a decreased space requirement for stock plants, flowering could be achieved in less time. There are several advantages associated with using petiole tissue rather than leaf tissue. There is greater ease in sterilization, as well as ease in sectioning the tissue for culture. Finally, if working with limited amounts of tissue which have not yet proven easily cultured the leaf cutting can be used as a backup. The production of new cultivars and the savings in space and time invested in an African violet crop could plausibly offset the initial investment in tissue culture facilities and equipment. The objectives of this project were: 1) to determine which BA concentration would result in the optimal growth of shoots, 2) to evaluate the relative productivity of regions along the petiole length, 3) to determine the time and origin of shoot initiation, and 4) to induce variation using colchicine treatment of petiole sections in vitro

Somatostatin Gene and Protein Expression in the Non-human Primate Central Extended Amygdala

Alterations in central extended amygdala (EAc) function have been linked to anxiety, depression, and anxious temperament (AT), the early-life risk to develop these disorders. The EAc is composed of the central nucleus of the amygdala (Ce), the bed nucleus of the stria terminalis (BST), and the sublenticular extended amygdala (SLEA). Using a non-human primate model of AT and multimodal neuroimaging, the Ce and the BST were identified as key AT-related regions. Both areas are primarily comprised of GABAergic neurons and the lateral Ce (CeL) and lateral BST (BSTL) have among the highest expression of neuropeptides in the brain. Somatostatin (SST) is of particular interest because mouse studies demonstrate that SST neurons, along with corticotropin-releasing factor (CRF) neurons, contribute to a threat-relevant EAc microcircuit. Although the distribution of CeL and BSTL SST neurons has been explored in rodents, this system is not well described in non-human primates. In situ hybridization demonstrated an anterior-posterior gradient of SST mRNA in the CeL but not the BSTL of non-human primates. Triple-labeling immunofluorescence staining revealed that SST protein-expressing cell bodies are a small proportion of the total CeL and BSTL neurons and have considerable co-labeling with CRF. The SLEA exhibited strong SST mRNA and protein expression, suggesting a role for SST in mediating information transfer between the CeL and BSTL. These data provide the foundation for mechanistic non-human primate studies focused on understanding EAc function in neuropsychiatric disorders

Transcriptional Profiling of Primate Central Nucleus of the Amygdala Neurons to Understand the Molecular Underpinnings of Early-Life Anxious Temperament.

BackgroundChildren exhibiting extreme anxious temperament (AT) are at an increased risk for developing anxiety and depression. Our previous mechanistic and neuroimaging work in young rhesus monkeys linked the central nucleus of the amygdala to AT and its underlying neural circuit.MethodsHere, we used laser capture microscopy and RNA sequencing in 47 young rhesus monkeys to investigate AT's molecular underpinnings by focusing on neurons from the lateral division of the central nucleus of the amygdala (CeL). RNA sequencing identified numerous AT-related CeL transcripts, and we used immunofluorescence (n = 3) and tract-tracing (n = 2) methods in a different sample of monkeys to examine the expression, distribution, and projection pattern of neurons expressing one of these transcripts.ResultsWe found 555 AT-related transcripts, 14 of which were confirmed with high statistical confidence (false discovery rate < .10), including protein kinase C delta (PKCδ), a CeL microcircuit cell marker implicated in rodent threat processing. We characterized PKCδ neurons in the rhesus CeL, compared its distribution with that of the mouse, and demonstrated that a subset of these neurons project to the laterodorsal bed nucleus of the stria terminalis.ConclusionsThese findings demonstrate that CeL PKCδ is associated with primate anxiety, provides evidence of a CeL to laterodorsal bed nucleus of the stria terminalis circuit that may be relevant to understanding human anxiety, and points to specific molecules within this circuit that could serve as potential treatment targets for anxiety disorders

Transcriptional Profiling of Primate Central Nucleus of the Amygdala Neurons to Understand the Molecular Underpinnings of Early-Life Anxious Temperament.

BackgroundChildren exhibiting extreme anxious temperament (AT) are at an increased risk for developing anxiety and depression. Our previous mechanistic and neuroimaging work in young rhesus monkeys linked the central nucleus of the amygdala to AT and its underlying neural circuit.MethodsHere, we used laser capture microscopy and RNA sequencing in 47 young rhesus monkeys to investigate AT's molecular underpinnings by focusing on neurons from the lateral division of the central nucleus of the amygdala (CeL). RNA sequencing identified numerous AT-related CeL transcripts, and we used immunofluorescence (n = 3) and tract-tracing (n = 2) methods in a different sample of monkeys to examine the expression, distribution, and projection pattern of neurons expressing one of these transcripts.ResultsWe found 555 AT-related transcripts, 14 of which were confirmed with high statistical confidence (false discovery rate < .10), including protein kinase C delta (PKCδ), a CeL microcircuit cell marker implicated in rodent threat processing. We characterized PKCδ neurons in the rhesus CeL, compared its distribution with that of the mouse, and demonstrated that a subset of these neurons project to the laterodorsal bed nucleus of the stria terminalis.ConclusionsThese findings demonstrate that CeL PKCδ is associated with primate anxiety, provides evidence of a CeL to laterodorsal bed nucleus of the stria terminalis circuit that may be relevant to understanding human anxiety, and points to specific molecules within this circuit that could serve as potential treatment targets for anxiety disorders

Dorsal Amygdala Neurotrophin-3 Decreases Anxious Temperament in Primates

BackgroundAn early-life anxious temperament (AT) is a risk factor for the development of anxiety, depression, and comorbid substance abuse. We validated a nonhuman primate model of early-life AT and identified the dorsal amygdala as a core component of AT's neural circuit. Here, we combine RNA sequencing, viral-vector gene manipulation, functional brain imaging, and behavioral phenotyping to uncover AT's molecular substrates.MethodsIn response to potential threat, AT and brain metabolism were assessed in 46 young rhesus monkeys. We identified AT-related transcripts using RNA-sequencing data from dorsal amygdala tissue (including central nucleus of the amygdala [Ce] and dorsal regions of the basal nucleus). Based on the results, we overexpressed the neurotrophin-3 gene, NTF3, in the dorsal amygdala using intraoperative magnetic resonance imaging-guided surgery (n = 5 per group).ResultsThis discovery-based approach identified AT-related alterations in the expression of well-established and novel genes, including an inverse association between NTRK3 expression and AT. NTRK3 is an interesting target because it is a relatively unexplored neurotrophic factor that modulates intracellular neuroplasticity pathways. Overexpression of the transcript for NTRK3's endogenous ligand, NTF3, in the dorsal amygdala resulted in reduced AT and altered function in AT's neural circuit.ConclusionsTogether, these data implicate neurotrophin-3/NTRK3 signaling in the dorsal amygdala in mediating primate anxiety. More generally, this approach provides an important step toward understanding the molecular underpinnings of early-life AT and will be useful in guiding the development of treatments to prevent the development of stress-related psychopathology

Medical and Household Characteristics Associated with Methicillin Resistant Nasal Carriage among Patients Admitted to a Rural Tertiary Care Hospital

Background Methicillin resistant Staphylococcus aureus (MRSA) poses a threat to patient safety and public health. Understanding how MRSA is acquired is important for prevention efforts. This study investigates risk factors for MRSA nasal carriage among patients at an eastern North Carolina hospital in 2011. Methods Using a case-control design, hospitalized patients ages 18 – 65 years were enrolled between July 25, 2011 and December 15, 2011 at Vidant Medical Center, a tertiary care hospital that screens all admitted patients for nasal MRSA carriage. Cases, defined as MRSA nasal carriers, were age and gender matched to controls, non-MRSA carriers. In-hospital interviews were conducted, and medical records were reviewed to obtain information on medical and household exposures. Multivariable conditional logistic regression was used to derive odds ratio (OR) estimates of association between MRSA carriage and medical and household exposures. Results In total, 117 cases and 119 controls were recruited to participate. Risk factors for MRSA carriage included having household members who took antibiotics or were hospitalized (OR: 3.27; 95% Confidence Interval (CI): 1.24–8.57) and prior hospitalization with a positive MRSA screen (OR: 3.21; 95% CI: 1.12–9.23). A lower proportion of cases than controls were previously hospitalized without a past positive MRSA screen (OR: 0.40; 95% CI: 0.19–0.87). Conclusion These findings suggest that household exposures are important determinants of MRSA nasal carriage in hospitalized patients screened at admission