‘Tonight Show’ Look Changes Under Leno : Television: With jazz band and more stylish set, show strikes younger pose.

Television’s late night institution, “The Tonight Show,” entered a new era Monday when Jay Leno took over as host and immediately gave the 38-year-old series a major face lift.

Leno, 42, only the fourth regular host in the show’s history--following Steve Allen, Jack Paar and Carson--introduced a new set, a new musical theme and a smaller, eight-piece band led by jazz saxophonist Branford Marsalis, 31. Together they seemed to exemplify a younger look for the program.

The new “Tonight” host, who was Carson’s substitute for five years, entered to a huge ovation. Referring to the reign of Carson, which ended Friday, Leno told his appreciative audience: “Let’s see how you all feel in 30 years.”

Leno then launched into his typical politically oriented monologue, principally targeting Vice President Dan Quayle. He said “The Tonight Show “ was “the one TV show that Dan Quayle hates even more than ‘Murphy Brown.’ ” Quayle criticized “Murphy Brown” last week because the lead character had a baby out of wedlock.

The new keynote song of “Tonight” is “Jay’s Theme,” written by Marsalis and reflecting his band’s elegant jazz sound. The set is designed to resemble a refurbished old theater, with pillars and a pink-purple curtain.

“It just felt right for Jay because he’s played almost every theater in the country,” said the new executive producer, Helen Kushnick. “It represents permanence.”

Carson’s set is entirely gone. The new set has Leno sitting at a traditional cherrywood desk with a leather top designed to conceal a small TV monitor on the right side. To his right are two chairs and a love seat in the middle, all soft purple. In front of them are two small, round, green marble tables.

The backdrop is a mural depicting a nighttime California coastline scene in soft shades of purple, gray and green. Numerous tropical plants complete the look.

Leno’s first guest was Billy Crystal, who entered in comic confusion, searching for Ed McMahon, Carson’s longtime sidekick, who is also gone. “Eddie M., Eddie M.,” Crystal said, looking around. He then told Leno: “I saw Ed McMahon on the corner with a sign that said: ‘Will Announce for Food.’ ”

Leno works without a sidekick, but has periodic exchanges with Marsalis--similar to the way late-night host David Letterman works with his bandleader, Paul Shaffer.

His voice comically cracking with emotion, Crystal also spoofed Bette Midler’s tearful farewell song to Carson on “Tonight” last Thursday. The song was a new version of “You Made Me Love You.”

Other guests on Leno’s debut included singer Shanice and economist Robert Krulwich.

Kushnick said that messages wishing Leno good luck have come from such show business names as Doc Severinsen, Carson’s musical conductor; Lorne Michaels, producer of “Saturday Night Live”; Robert Morton, producer of “Late Night with David Letterman”; super agent Michael Ovitz, who represents Letterman, and the Oak Ridge Boys.

On hand for Leno’s launching was Carson’s longtime executive producer, Fred de Cordova, who is a temporary consultant to the Leno show.

Leno’s debut took place in Studio Three at NBC in Burbank, but the series soon will return to its regular home, nearby Studio One, which is undergoing renovations.

On Monday morning, Leno appeared on NBC’s “Today” show, where he told interviewer Katie Couric that he does not feel the heat as Carson’s successor:

“It wasn’t as if they gave me the job and I had to prove something to get it. It seems fairly comfortable. I’m not one of those high-pressure people. If it works, it works.”

Leno has hosted “Tonight” more than 330 times since 1987.