The Harvard community is struggling to cope with the absence of Loeb Professor of Biophysics and Biochemistry Don C. Wiley, who remained missing yesterday, 12 days after his car was found abandoned in Tennessee on a bridge spanning the Mississippi River.

A post-doctoral fellow in a lab that shares space and equipment with Wiley’s lab described the atmosphere there as “grim.”

“We’re continuing with our daily routines, [but] it’s in the back of everyone’s mind at all times,” said the fellow, who works in the lab of Higgins Professor of Biochemistry and Molecular Biology Stephen C. Harrison.

Harrison would not speak to Crimson reporters, and the fellow, who asked to remain anonymous, said the molecular and cellular biology department circulated an e-mail telling students in the department to refer all questions about Wiley to the University’s communications office.

Although the fellow said the University is being supportive of Wiley’s students and colleagues, they continue to struggle with the uncertainty of the situation.

“People are kind of coping in their own way. It’s hard not having news,” he said.

Memphis police said yesterday brought no new developments in the case. Wiley’s empty rental car was found abandoned with a full tank of gas and the keys in the ignition at 4 a.m. Nov. 16, and the professor was last seen in a Memphis hotel four hours earlier. Police have found no evidence of foul play or suicide.

Meanwhile, a guest lecture Wiley had been scheduled to give yesterday for Immunology 201, “Principles of Immunology,” a graduate-level course, was canceled, said Erica L. Maier ’02, a student in the class.

Wiley and Harrison are currently scheduled to co-teach Biological Sciences 56, “Structure, Function and Physical Chemistry of Macromolecules,” in the spring.

“The chair of the [biological sciences] department has, of course, made all the appropriate arrangements, both for the curriculum and for the continuing advice and help for Professor Wiley’s graduate students,” Dean of the Faculty Jeremy R. Knowles wrote in an e-mail.

One of Wiley’s former students said his talents as a professor would be hard to replace if he is not found.

“He always seemed excited about teaching, and he did a good job making [the material] as understandable as possible,” said Christopher L. Pierce ’02, who took B.S. 56 last spring.

Jonathan P. Jacobs ’02, another of Wiley’s B.S. 56 students, said Wiley “was enthusiastic and gave interesting examples.”

Knowles, a chemist by training, called Wiley a “good personal friend” and a “distinguished colleague.” He wrote that the “disappearance is deeply worrying, and quite inexplicable.”

Professor of Statistical Sciences Marvin Zelen, who attended the Memphis Scientific Advisory Board meeting and banquet where Wiley was last seen, said that Wiley presented a “very complete report” on structural biology on Nov. 15, the day before he disappeared.