Context: Canadian tax environment, proprietorship 

Assumption: A Proprietorship results in flow-through of
income/expense, loss/gain to personal income statement

Background:
I am a full-time employee planning to develop an investment portfolio
OR a business part-time.  I wanted to understand a specific tax
implication (among many) of developing an investment
portfolio/business outside of a tax sheltered environment like an
RRSP.I am planning to fund my business/portfolio using debt capital.

Question:
My question is, can I use this initial investment amount as a business
expense and hence a tax deduction to reduce my overall taxable income?

Please correct above assumption if wrong and provide sufficient
reference with response (e.g. a single authoritative link would be
enough)

Thanks