- Author: Helen Dahlke
To overcome the problems that have plagued traditional tracer studies we have developed a new tracer concept that utilizes bio-molecular nanotechnology. We use short, artificially made DNA sequences that are wrapped into a safe, biodegradable polymer composed of polylactic acid (PLA) to protect the DNA from being eaten by microbes during the transport process. Because DNA is made of the four basic building blocks adenine (A), thymine (T), guanine (G) and cytosine (C) (Fig. 1), which can be combined in any random order, our unique DNA-based tracers allow, in theory, fabrication of an enormous number of unique tracers (approximately 1.61 x 1060) with identical transport properties. Because of their unique DNA sequence the tracers have unique IDs, thus, we can use multiple tracers at the same time in the same watershed. The amount of tracer present in a streamwater sample can be estimated with real-time quantitative polymerase chain reaction (qPCR), a method commonly used in molecular biology, which determines the number of DNA copies present in a sample. Finally, during the tracer fabrication process, we can alter the size of the tracer particles to anything from 200 nanometers (size of a virus) to 1 micrometer (size of colloids or bacteria), which helps mimicking the physical transport properties of the pollutant of interest.
In the next two years we will test differently sized DNA tracers in a well-studied, small experimental watershed at SFREC to test their use for identifying hydrologic flow pathways. This study will provide invaluable information for the understanding of processes in hydrologic systems that can be used to improve hydrological and biogeochmical models used to predict transport of pollutants from hillslopes to streams. To achieve this broader goal, we will distribute 5 different DNA tracers at 5 different locations at incrementally increasing distances from a trenched hillslope at SFREC and measure the tracer breakthrough curves in a runoff collection system and the watershed outlet. The injection locations will be chosen to represent a range of specific soil-landscape characteristics such as places with relatively deep soils, shallow soils and areas where flow visually concentrates in the landscape. With the tracer experiments we also hope to quantify preferential flow pathways (e.g. macropore flow) in the watershed. Preferential flow is hypothesized to lead to shorter travel times of water and pollutants through soils and the vadose zone. Because of the variable size of our DNA tracers (0.1-0.4 µm) they could be particularly useful for quantifying macropore and preferential flow because we expect that a small fraction of the tracers will be filtered out in the soil matrix while the majority of the DNA tracers will move along the most rapid flow pathways. The results from these experiments, if successful, will provide improved estimates of the time it takes for water and solutes to travel through the soil to streams, which will allow us to more accurately predict the risk of pollution of streams and surface water bodies during storm events.
- Author: Mckenna Kane
Over the past several months, Dr. John Angelos of UC Davis School of Veterinary Medicine has been working on a vaccine for one of the cattle industry's most widespread diseases: infectious bovine keratoconjunctivitis (IBK), commonly known as pinkeye. IBK is caused by an infection of Moraxella bovis in the eye that leads to corneal ulcers, scarring and, in extreme cases, permanent blindness.
According to Dr. Angelos, the disease presents an economic loss for the producer due to the cost of labor to treat the infection, the cost of the antibiotic treatment as well as reduced weight gains. He also notes the disease has certain animal welfare considerations; it can be extremely painful for the infected animal. Currently, there is not an effective vaccine to prevent the painful disease, only a costly treatment.
Dr. Angelos has been working on this vaccine since April, but the vaccine has been developing since the early 2000s. This summer, Dr. Angelos is testing the effectiveness of an intranasal vaccine, rather than the subcutaneous version of previous studies. His hypothesis states “calves vaccinated intranasally with Moraxella bovis cytotoxin (MbxA) will have a significantly reduced cumulative proportion of corneal ulcerations associated with naturally occurring IBK versus control calves.”The team collected blood and tear samples from approximately 180 animals at the UC Sierra Foothill Research and Extension Center and administered either the vaccine or a placebo assigned to the animal. In order to keep the results unbiased, Dr. Angelos did not know which vaccine he was giving to the animals; they were labeled “A” or “B.”
Each week thereafter, he and several students have examined the entire herd, noting those with active cases of pinkeye. If an animal shows signs of pinkeye, an innocuous stain is administered in the eye to see the ulcer, a measurement and a picture are taken to monitor the ulcer from week to week. At the end of the study, animals with active cases of pinkeye will be given antibiotics to cure the pinkeye.
Ultimately, the goal of the research is to create a vaccine that will prevent the disease from occurring. Dr. Angelos explained that although this vaccine has made great advancements, it will need to have subsequent testing and trials to determine if it is viable in the industry. In the video below, Dr. Angelos explains his research and the role of the Sierra Foothill Research and Extension Center in developing a vaccine for infectious bovine keratoconjunctivitis.
- Author: Megan G Osbourn
As precipitation more frequently departs from the historical range of variability, maintaining stability in forage production will be a critical management priority in Californian rangelands. A key mechanism that can lead to stability in forage production is compensatory dynamics, where plant functional groups respond differently to climate fluctuations (e.g.,taprooted forbs like Erodium tolerate drought, annual grasses are highly productive in non-drought conditions).
Researchers hypothesize that trade-off among functional groups should buffer the response of overall forage production to climate variability and better retain soil nutrients in dry-wet up cycles. The specific objectives are to: 1) quantify relationships among the fate and retention of nitrogen, soil moisture dynamics, and species compensatory dynamics in drought and non-drought conditions; and 2) incorporate these relationships into process-based models of nitrogen retention and forage production in rangelands.
This project will ultimately lead to more informed decision-making for ranchers interested in optimizing forage production and nutrient retention in the face of a highly variable future climate. It addresses an often overlooked but critical component to the stability of ecosystem processes: functional diversity of forage groups.
Researcher, Lauren Hallet explains the preliminary progress of this project in detail in the below video. Stay tuned for more information as samples are taken this spring.
Principle Investigator: Dr. Katherine Suding, ESPM, UC Berkeley