Biology Projects 2013

Why do Black Widows have a red spot?

Faculty Mentor - Dr. Carl Kloock

The red spot on the ventral surface of the Black Widow spider's abdomen is often cited as an example of Aposematic (warning) coloration. However, to date there has actually been no experimental test of this function and, in fact several other functions have been proposed, including attracting prey. By experimentally manipulating Black Widows in the field, this summer's REVSUP project will test these and other hypotheses regarding the function of this distinctive coloration. In addition, as part of the ongoing development of an electronic field guide and checklist of the local spider communities (see www.csub.edu/~ckloock/Spiderguide/key.pdf), we will collect, identify and photograph spiders from nearby habitats. As part of the project participants will build some of the equipment necessary for the experiment. We will handle live Black Widow spiders: these are potentially dangerous animals, but can be handled safely as long as proper techniques, which participants will be taught, are followed. Because spiders are largely nocturnal organisms, we will be working for at least part of the project during the late evenings and into the early morning hours.

Diversity of Microcrustaceans and Detection of the amphibian pathogen Batrachochytrium dendrobatidis in ponds of the Southern San Joaquin Valley and the foothills of the Sierra Nevada (CA) by Polymerase Chain Reaction (PCR)

Faculty Mentor - Dr. Antje Lauer

Batrachochytrium dendrobatidis (Bd) is a fungal pathogen that has been identified as the cause in the massive decline of various amphibian species worldwide. Along with the decline of other species in the foothills of the Sierra Nevada due to Chytridiomycosis, the mountain yellow legged frog (Rana muscosa) is severely threatened by Bd in the higher Sierra Nevada (CA). Also, a decline of diverse microcrustacean species, which are natural predators of Bd, has been observed in some areas in the Sierra Nevada Mountains (e.g. Lake Tahoe). Microcrustaceans can also produce dormant, diapausing eggs during adverse environmental conditions that can lie dormant in sediment for decades until conditions improve and can serve as an indicator for the diversity of Microcrustaceans in the past. By investigating the water and sediment of ponds and lakes with microscopy and molecular biotechnological methods, we want to determine the presence of Bd in the watercolumn and also analyze the status quo of Microcrustaceans in the water. Furthermore, we like to quantitatively determine Bd in the water samples by using Real-Time PCR.

Do bacteria found on the skin of the North American Bullfrog (Rana catesbeiana) play a role in protecting it from the fungal pathogens?

Faculty Mentor - Dr. Kathleen Szick-Miranda

This study focuses on the bacterial diversity found on the skin of the Northern American Bullfrog Rana catesbeiana, an invasive species in California that is able to successfully outcompete other native amphibian species. One reason that explains its success is that it is immune to a variety of amphibian diseases including Chydridiomycosis, a skin disease caused by a fungus known as Batrachochytrium dendrobatidis (Bd). Chytridiomycosis is responsible for major amphibian declines worldwide. The reasons why the bullfrog can get infected, but does not succumb to the disease are not known. Recent research suggests that resident skin bacteria can play a role in protecting amphibians against Bd. Our study focuses on the antifungal ability of the cutaneous bacteria of R. catesbeiana isolated from both adults and juveniles (tadpoles). Participants in this research project will test bacteria, isolated from bullfrog skin, on their antifungal capability against potentially pathogenic fungi. In addition, participants will learn the fundamentals of research design, analysis and interpretation. The data collected from this project may have the potential to widely impact global amphibian conservation as well as human health issues by identifying probiotics that can lead to the discovery of potential antibiotics or novel chemotherapeutic compounds in the future.