Microbiology - Micro Organisms - Discussion

I know that archae withstand extreme temperatures.

What is nuclear membrane temperature?

Absence of a nuclear membrane temperature please explain this sentence. I can't understand.

Archaea: cell membrane contains ether linkages; cell wall lacks peptidoglycan; genes and enzymes behave more like Eukaryotes; have three RNA polymerases like eukaryotes; and extremophiles

Bacteria: cell membrane contains ester bonds; cell wall made of peptidoglycan; have only one RNA polymerase; react to antibiotics in a different way than archaea do.

Archaea lipids are based upon the isoprene sidechain: they are long chains with complex side-chains and often cyclopropane or cyclohexane rings. Although isoprenoids play an important role in the biochemistry of many organisms, only the archaea use them to make phospholipids. These branched chains may aid archaean membranes from leaking at high temperatures.