Complex sentence: SJVR operates the southern portion of the line from Oxalis to Fresno and was at one time owned by Port Railroads, Inc. (PRI; a Kyle subsidiary) and operated by the SJVR.
Split into simpler sentences: SJVR operates the southern portion of the line from Oxalis to Fresno. This line was at one time owned by Port Railroads, Inc. (PRI; a Kyle subsidiary) and operated by the SJVR.