College of Tropical Agriculture and Human Resources

About: College of Tropical Agriculture and Human Resources is a based out in . It is known for research contribution in the topics: Population & Soil water. The organization has 513 authors who have published 604 publications receiving 15798 citations.

Protease inhibitors and reproduction of reniform nematode in pineapple

Abstract: Endogenous protease inhibitors (PIs) in the roots of Smooth Cayenne pineapple clones may affect the growth of the plant-parasitic nematode Rotylenchulus reniformis. In pineapple, reniform population densities remain atypically near preplant levels for 6–9 months after pineapple planting. A potted plant experiment was conducted to determine if the PI present in pineapple roots affected nematode reproduction and possibly account for the observed nematode field population dynamics. Pineapple PI activity increased for the first 6 months after planting and was higher in nematode-inoculated plants. Nematode reproduction, however, was not correlated to PI activity. In a second experiment, PI activity was concentrated in the portion of the roots nearest the pineapple butt where nematode population densities were highest. The behaviour of the PI in pineapple roots suggested a defensive role, such as systemic acquired resistance, against R. reniformis.

Mammal-exclusion fencing improves the nesting success of an endangered native Hawaiian waterbird

Abstract: Invasive predator control is often critical to improving the nesting success of endangered birds, but methods of control vary in cost and effectiveness. Poison-baiting or trapping and removal are relatively low-cost, but may have secondary impacts on non-target species, and may not completely exclude mammals from nesting areas. Mammal-exclusion fencing has a substantial up-front cost, but due to cost savings over the lifetime of the structure and the complete exclusion of mammalian predators, this option is increasingly being utilized to protect threatened species such as ground-nesting seabirds. However, non-mammalian predators are not excluded by these fences and may continue to impact nesting success, particularly in cases where the fence is designed for the protection of waterbirds, open to an estuary or wetland on one side. Thus, there remains a research gap regarding the potential gains in waterbird nesting success from the implementation of mammal-exclusion fencing in estuarine systems. In this study, we compared the nesting success of endangered Hawaiian Stilts (Ae'o; Himantopus mexicanus knudseni) within a mammal-exclusion fence to that of breeding pairs in a nearby wetland where trapping was the sole means for removing invasive mammals. We predicted success would be greater for breeding pairs inside the exclusion fence and the hatchlings inside the enclosure would spend more time in the nesting area than hatchlings at the unfenced site. During a single breeding season following construction of a mammal-exclusion fence, we used motion-activated game cameras to monitor nests at two sites, one site with mammal-exclusion fencing and one site without. Clutch sizes and hatch rates were significantly greater at the fenced site than the unfenced site, but time spent by chicks in the nesting area did not differ between sites. These results add to the mounting body of evidence that demonstrates the effectiveness of mammal-exclusion fencing in protecting endangered birds and suggests it can aid endangered Hawaiian waterbirds toward recovery. These results also suggest that the single greatest predatory threat to the Hawaiian Stilt may be invasive mammals, despite a host of known non-mammalian predators including birds, crabs, turtles, and bullfrogs, as the complete exclusion of mammals resulted in significant gains in nesting success. As additional fences are built, future studies are necessary to compare nesting success among multiple sites and across multiple seasons to determine potential gains in fledging success and recruitment.

Examining the Influence of Cultural Immersion on Willingness to Try Fruits and Vegetables among Children in Guam: The Traditions Pilot Study

Abstract: This pilot study examined the influence of cultural immersion on willingness to try fruits and vegetables (FV) among children 3–12 years old in three summer camps in Guam with different cultural exposure levels: cultural immersion camp (CIC), high exposure; university day camp (UDC), moderate exposure; and recreational sports camp (RSC), zero exposure. Children, ages 3–12 years old for CIC and UDC and 5–12 years old for RSC, participated: CIC (n = 47), UDC (n = 23), and RSC (n = 33). Children’s willingness to try FV was assessed with the Adapted WillTry tool before and after each program. Whole FV intakes were assessed concurrently using the mobile food record in CIC and UDC. Using multivariate regression, WillTry post-assessment outcomes were modeled adjusting for pre-assessment, child characteristics, exposure, and parent cultural affiliation. Unique to the Adapted WillTry tool are three FV scales, local novel, local common, and imported, which are classified by source (local or imported) and/or familiarity (novel or common). WillTry adjusted mean FV post-scores by highest exposure camp to lowest were 2.2, 2.3, and 2.2 for local novel and 2.6, 2.6, and 2.6 for local common. No differences among camps were significant; however, there was an increase in the willingness to try scores for all FV score types and camps. The Traditions pilot study demonstrated: (1) feasibility of a multi-arm parallel design using existing community programs in limited-resource environments and (2) further examination of nutrition education components and contexts are needed to understand diet behaviors of indigenous populations.

In Vitro Blood-Brain Barrier Modeling adapted for Peripheral Blood Mononuclear Cell Transmigration from HIV-Positive Patients for Clinical Research on Therapeutic Drug Intervention.

Abstract: Objective: HIV-associated cognitive impairment (HACI) continues to persist for HIV-seropositive individuals who are on antiretroviral therapy (ART). HACI develops in part when HIV-infected monocytes (MOs) transmigrate through the blood–brain barrier (BBB) and secrete pro-inflammatory cytokines and chemokines, which leads to neuronal damage. In vitro BBB models are important tools that can elucidate mechanisms of MO transmigration. Previously described in vitro BBB models relied on pathology specimens, resulting in potentially variable and inconsistent results. This project reports on a reliable and consistent alternative in vitro BBB model that has the potential to be used in clinical research intervention studies analyzing the effects of ART on the BBB and on MO transmigration. Methods: A bilayer BBB model was established with commercially available astrocytes and endothelial cells on a 3μm PET membrane insert to allow the contact of astrocytic foot processes with endothelial cells. Inserts were cultured in growth medium for 7 days before exposure to HIV- or HIV+ peripheral blood mononuclear cells (PBMCs). PBMCs were allowed to transmigrate across the BBB for 24 hours. Results: Confluency and integrity measurements by trans-endothelial electrical resistance (TEER) (136.7 ± 18.3Ω/cm2) and permeability (5.64 ± 2.20%) verified the integrity of the in vitro BBB model. Transmigrated MOs and non-MOs were collected and counted (6.0x104 MOs; 1.1x105 non-MOs). Markers indicative of glial fibrillary acidic protein (GFAP), von Willebrand factor (vWF), and p-glycoprotein (Pgp) were revealed in immunofluorescence staining (IF), indicating BBB phenotype and functionality. Conclusion: Potential applications for this model include assessing the HIV DNA copy numbers of transmigrated cells (pre- and post-targeted ART) and understanding the role of oxidative stress related to HIV DNA and HACI.