Principles of Biology II Semester II - 2017/2018Class Assignment-1Due Lecture 7Topic 1. Eukaryote DiversityIn summer 2005, a devastating red tide crippled the shellfish industry along theAtlantic coast of North America from Canada to Massachusetts. This red tide wasproduced by a bloom of dinoflagellates of the genusAlexandrium. These protistsproduce a powerful toxin that accumulates in clams, mussels, and oysters. A personwho eats a mollusk contaminated with the toxin can experience a syndrome known asparalytic shellfish poisoning. The losses to the shellfish industry in 2005 were estimatedat $50 million, and many people were sickened by eating mollusks that were harvestedbefore the problem was diagnosed.Several species of dinoflagellates produce toxic red tides in many parts of theworld. Along the Gulf of Mexico, red tides caused by dinoflagellates of the genusKareniaproduce a neurotoxin that affects the central nervous systems of fish, whichbecome paralyzed and cannot respire effectively. Huge numbers of dead fish wash upon Gulf Coast beaches during aKareniared tide. In addition, wave action can produceaerosols of theKareniatoxin, and these aerosols often cause asthma-like symptoms inhumans on shore.After the losses that resulted from the 2005 red tide, biologists at the Woods HoleOceanographic Institution (WHOI) on Cape Cod began to monitor and modeldinoflagellate populations off the New England coast. If biologists could accuratelyforecast future blooms, people in the area could be made aware of the problem inadvance and adjust the shellfish harvest (and their eating habits) accordingly.Biologists from WHOI monitored counts of dinoflagellates in the water and inseafloor sediments. They also monitored river runoff, water currents, watertemperature and salinity, winds, and tides. An additional environmental factor was the“nor’easter” storms common along the New England coast. By correlating theirmeasurements of these environmental factors with dinoflagellate counts, biologistsproduced a model that predicted growth of dinoflagellate populations.In spring 2008, the WHOI team determined that all the factors were in place toproduce another red tide like the one of 2005—if a nor’easter occurred to blow thedinoflagellates toward the coast. A nor’easter did occur at just the wrong time, andanother red tide materialized in summer 2008, just as predicted. But this time, peoplewere warned. Shellfish harvesters adjusted their harvest, and many fewer people wereharmed by eating toxic mollusks.Red tides are harmful, but can dinoﬂ agellates also be benefi cial to marineecosystems?
Topic 2. Fungal MetabolitesAlexander Fleming was already a famous scientist in 1928, but his laboratorywas often a mess. That year he was studying the properties ofStaphylococcusbacteria,the agents of dangerous staph infections. In August, he took a long vacation with hisfamily. When he returned in early September, he found that some of his petri dishes ofStaphylococcushad become infested with a fungus that killed many of the bacteria.