Refining
UPDATE 1-Brent drops below $110 after China PMI data misses mark
* Coming Up: U.S. ISM manufacturing; 1400 GMT (Updates prices)
UPDATE 4-SEC steps up probe of Chesapeake, CEO McClendon
* Shares close 2.4 percent lower
(Adds closing share price, company comment)
WRAPUP 1-Syrian opposn chief under fire for talks with Assad allies
* Opposition leader met Russian, Iranian and U.S. officials
