The preprotein for chloroplasts may contain a stromal import sequence or a stromal and thylakoid targeting sequence. The majority of preproteins are translocated through the Toc and Tic complexes located within the chloroplast envelope. In the stroma the stromal import sequence is cleaved off and folded as well as intra-chloroplast sorting to thylakoids continues. Proteins targeted to the envelope of chloroplasts usually lack cleavable sorting sequence.
The first attempt to construct a canal through what was then Colombia's province of Panama began on 1 January 1881. The project was inspired by the diplomat Ferdinand de Lesseps, who was able to raise considerable finance in France as a result of the huge profits generated by his successful construction of the Suez Canal. Although the Panama Canal would eventually have to be only 40% as long as the Suez Canal, the former would prove to be far more of an engineering challenge, due to the tropical rain forests, the climate, the need for canal locks, and the lack of any ancient route to follow.
De Lesseps wanted a sea-level canal as at Suez but only visited the site a few times, during the dry season which lasts only four months of the year. His men were totally unprepared for the rainy season, during which the Chagres River, where the canal started, became a raging torrent, rising up to 35 feet (10 m). The dense jungle was alive with venomous snakes, insects and spiders, but the worst aspect was the yellow fever and malaria (and other tropical diseases) which killed thousands of workers: by 1884 the death rate was over 200 per month. Public health measures were ineffective because the role of the mosquito as a disease vector was then unknown. Conditions were downplayed in France to avoid recruitment problems, but the high mortality rate made it difficult to maintain an experienced workforce.
The main cut through the mountain at Culebra had to continually be widened, and the angle of its slopes reduced, to minimize landslides into the canal. Steam shovels were used in the construction of the canal, and they were purchased from Bay City Industrial Works, a business owned by William L. Clements in Bay City, Michigan. Other mechanical and electrical equipment was limited in its capabilities, and steel equipment rusted rapidly in the climate.
In France, de Lesseps kept the investment and supply of workers flowing long after it was obvious that the targets were not being met, but eventually the money ran out. The French effort went bankrupt in 1889 after reportedly spending US$287,000,000 and losing an estimated 22,000 lives to disease and accidents, wiping out the savings of 800,000 investors. Work was suspended on May 15, and in the ensuing scandal, known as the Panama affair, various of those deemed responsible were prosecuted, including Gustave Eiffel. De Lesseps and his son Charles were found guilty of misappropriation of funds and sentenced to five years' imprisonment, though this was later overturned, and the father, at 88, was never imprisoned.
In 1894, a second French company, the Compagnie Nouvelle du Canal de Panama, was created to take over the project. A minimal workforce of a few thousand people was employed primarily to comply with the terms of the Colombian Panama Canal concession, to run the Panama Railroad, and to maintain the existing excavation and equipment in salable condition. The company sought a buyer for these assets, with an asking price of US$109,000,000. In the meanwhile they continued with enough activity to maintain their franchise, and Bunau-Varilla eventually managed to persuade de Lesseps that a lock-and-lake canal was more realistic than a sea-level canal.