Female English Lab in heat

Question
My female lab Bella is in heat for her first time.  We also have a twelve year old NEUTERED black lab.  My question is will this be a problem between the two of them?  Will my female become aggressive towards the fixed male or vice versa?

Answer
Keep them apart.  Neutered males will mate with a female in heat.  There will be no puppies, but a chance of infection.  Get her spayed when it is all over.  Your question suggests to me that you have not done all the hard work educating your self that it takes to breed quality dogs.  We are slaughtering 10,000,000 dogs a year for lack of homes.  Most of the problem comes from people knowing too little about dogs and failing to spay/neuter.