From and after the effective date of this act, all railroad companies operating in the State of Oklahoma are hereby required to grant leave of absence to their employees who desire to run for or seek public office, or who are required to serve in any government position, military or civil, or who have been elected or appointed to public office, or who are required to serve jury duty in the courts of this state. During such leave of absence such employee shall retain and accumulate seniority, and at the termination of such service shall be reinstated with full seniority, and without an interrupted service record, or without any rights or privileges denied him. Provided, however, that at the end of the period of his leave of absence granted hereunder, said employee shall report for duty within fifteen (15) days thereafter.