Mathematical Modeling as a Tool in the Fight Against Malaria
The study of infectious disease epidemiology has had a fairly long history. For several hundred years, scientists have studied disease outbreaks. Notably, Ronald Ross and Daniel Bernoulli produced various models to accurately predict and track the spread of infections throughout a human population. These models, which were applied to diseases such as smallpox and plague, took into account several important features of the outbreak including the number of people infected and the percentage of the vector (the insect that transmits a disease to humans) containing the actual pathogen.
One of the most prominent diseases to which models have been applied is malaria, which is caused by the protozoan Plasmodium. Dr. John Marshall, assistant professor in the School of Public Health at the University of California, Berkeley, has for several years been using modeling to predict the outcomes of certain control strategies for malaria. Malaria follows many general rules used in non-specific modeling of disease transmission (see Figure 1), but has some unique aspects like incubation period (the time in which the parasite needs to grow inside the mosquito). The models account for host parameters including whether the patient is symptomatic, the patient’s immunity and the patterns of how people travel. This last tenet is especially important as human population movement affects how malaria itself actually spreads. Vector parameters contribute to the model as well, such as how long the mosquito lives and its sensitivity to climate and geography. Ultimately, the model can be tested against data from a real outbreak and then tweaked to fit the data more precisely.
Figure 1: Complexity of the Malarial Transmission Model. This diagram represents the factors that must be accounted for when making predictions about the spread of malaria through human populations. Important factors include whether the patient shows symptoms that doctors can see and if the patient can be treated in time.
The Evolution of Fungus Farming Ants, and How They Partnered with Microbes for Crop Protection
Fungus-farming ants stand as a testament to the overlooked marvels of the insect world, likely one of the reason’s why Dr. Jeffrey Sosa has dedicated the better part of his time as a researcher to elucidating the hidden intricacies of their biology. Having discovered over 30 species so far over the course of his career, few researchers can say with such confidence that we’ve only scratched the surface when it comes to understanding this enthralling tribe of insects.
Agriculture as defined by Dr. Sosa, is the deliberate planting of the precursors of food products in substrate provided by the environment such as soil or mineral beds while also improving the growing conditions to maximize growth of the harvestable food product. Often associated with humans, there are actually at least 3 other organisms, all of which are insects, that exhibit this behavior. The most advanced example of insect farming are the fungus-farming ants, which are part of the tribe Attini and are restricted to the New World. Unlike humans, these diminutive farmers seem to have developed agriculture at one point in history: around the time mammals were establishing on the planet. Though Leaf-cutter ants are the most well-known of these insects, they only make-up about 20% of the described fungus-farming species.
How Spiderman got his Powers: A Look into Lateral Gene Transfer
“Actually, Spiderman’s powers have nothing to do with radioactivity,” Dr. Julie Dunning Hotopp clarified to the roomful of entomologists. “It was the transfer of spider DNA into his genome.” While the ability to climb walls or shoot webs out your wrists (or worse) is pure science fiction, the transfer of DNA between two different species does actually occur. Dr. Dunning Hotopp explained that this process, known as lateral gene transfer (LGT), is quite widespread and the advent of genome sequencing (determining the chemical code that make an organism unique) in the last decade has greatly expanded our knowledge on the prevalence and role of foreign DNA in animals
Demonstrating high LGT frequency in invertebrates, Dr. Dunning Hotopp’s team detected LGT from the bacterial endosymbionts Wolbachia in over 30% of sequenced arthropod genomes. Wolbachia is an intracellular bacterial parasite/mutualist with complex host interactions. While LGT from bacteria to animals often has no benefit to a host, in certain cases it can be advantageous. For example, the coffee berry borer, a major pest to coffee growers, and the brown marmorated stink bug both have a gene originally acquired from bacteria. The gene, HhMAN1, codes for the protein mannanse and enables insects to digest plant sugars.
Mitigation of N2O emissions using conservation tillage in vegetable fields transitioning to organic productions