<p style="text-align: justify;">Maize line TC1507 was genetically modified to contain two novel genes, <i>cry1Fa2</i> and <i>pat</i>, for insect resistance and herbicide tolerance respectively. Both genes were introduced into the parental maize hybrid line Hi-II by particle acceleration (biolistic) transformation.</p>

<p style="text-align: justify;">The <i>cry1Fa2</i> gene, isolated from the common soil bacterium <i>Bacillus thuringiensis</i> (<i>Bt</i>) var. <i>aizawai</i>, produces the insect control protein Cry1F, a delta-endotoxin. Cry proteins, of which Cry1F is only one, act by selectively binding to specific sites localized on the lining of the midgut of susceptible insect species. Following binding, pores are formed that disrupt midgut ion flow, causing gut paralysis and eventual death due to bacterial sepsis. Cry1F is lethal only when eaten by the larvae of lepidopteran insects (moths and butterflies), and its specificity of action is directly attributable to the presence of specific binding sites in the target insects. There are no binding sites for the delta-endotoxins of <i>B. thuringiensis</i> on the surface of mammalian intestinal cells, therefore, livestock animals and humans are not susceptible to these proteins.</p>

<p style="text-align: justify;">The Cry1F protein expressed in TC1507 provides protection against European corn borer (ECB), southwestern corn borer (SWCB), fall armyworm (FAW), black cutworm (BCW), and some control of corn earworm (CEW).</p>

<p style="text-align: justify;">In addition to the <i>cry1Fa2</i> gene, TC1507 was developed to allow for the use of glufosinate ammonium, the active ingredient in phosphinothricin herbicides (Basta&reg;, Rely&reg;, Liberty&reg;, and Finale&reg;), as a weed control option, and as a breeding tool for selecting plants that have the insect-tolerant <i>cry1F</i> gene. Glufosinate chemically resembles the amino acid glutamate and acts to inhibit an enzyme, called glutamine synthetase, which is involved in the synthesis of glutamine. Essentially, glufosinate acts enough like glutamate, the molecule used by glutamine synthetase to make glutamine, that it blocks the enzyme&#39;s usual activity. Glutamine synthetase is also involved in ammonia detoxification. The action of glufosinate results in reduced glutamine levels and a corresponding increase in concentrations of ammonia in plant tissues, leading to cell membrane disruption and cessation of photosynthesis resulting in plant withering and death.</p>

<p style="text-align: justify;">Glufosinate tolerance in TC1507 maize is the result of introducing a gene encoding the enzyme phosphinothricin-N-acetyltransferase (PAT) isolated from the common aerobic soil actinomycete, <i>Streptomyces viridochromogenes</i>, the same organism from which glufosinate was originally isolated. The PAT enzyme catalyzes the acetylation of phosphinothricin, detoxifying it into an inactive compound.</p>
