Here’s a source you’d like to integrate with your argument:

“Whenever molecular biologists advertise the benefits of
genetically-enhanced foods, we must temper their enthusiasm with
our own common sense reservations. Large tomatoes in January
and giant strawberries in October are sure signs that nature has
been tampered with. McCormick & Dodge, a Chicago research firm,
reports that in an average American grocery store, as much as 35%
of the produce sold has been genetically altered. We know this, and
we should not accept this.”

Janis Turner, “Genetics, Food, and the Common Good.”
American Health 19.5 (May 2009): 131.

You might begin your paragraph like this (includes both the language of transition

and the language of a topic sentence):

The use of genetics to enhance food production is more common than
most people realize.

Now, add in the resource material to explain and elaborate on this topic sentence:

The use of genetics to enhance food production is more common than most

people realize. The evidence can be found in the local grocery store: "Large

tomatoes in January and giant strawberries in October are sure signs that

nature has been tampered with" (Turner 131).

--  or  (to add resource material into the syntax of your own sentence) --

The use of genetics to enhance food production is more common than most

people realize. When we discover "[l]arge tomatoes in January and giant

strawberries in October" on our grocer's shelves, we have "sure signs that

nature has been tampered with" (Turner 131).

Consider using a "signal phrase," which alerts the reader that borrowed material

is about to be presented (and should provide credentials of the author, too):

The use of genetics to enhance food production is more common than most

people realize. Author Janis Turner, a research scientist writing in the journal

American Health, reports that when we discover "[l]arge tomatoes in January

and giant strawberries in October" on our grocer's shelves, we have "sure

signs that nature has been tampered with" (131).

In each case, the topic sentence makes the larger point, and the evidence from your

resource material provides the details and support for the topic sentence. When you
include both discussion and illustration, consider using research paragraphs that have

more heft and substance than normal composition assignment paragraphs.