Bengal tigers are highly endangered and knowledge on adaptive genetic variation can be essential for efficient conservation and management. Here we present the first assessment of allelic variation in major histocompatibility complex (MHC) class I and MHC class II DRB genes for wild and captive tigers from India. We amplified, cloned, and sequenced alpha-1 and alpha-2 domain of MHC class I and beta-1 domain of MHC class II DRB genes in 16 tiger specimens of different geographic origin. We detected high variability in peptide-binding sites, presumably resulting from positive selection. Tigers exhibit a low number of MHC DRB alleles, similar to other endangered big cats. Our initial assessment-admittedly with limited geographic coverage and sample size-did not reveal significant differences between captive and wild tigers with regard to MHC variability. In addition, we successfully amplified MHC DRB alleles from scat samples. Our characterization of tiger MHC alleles forms a basis for further in-depth analyses of MHC variability in this illustrative threatened mammal.

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The individual steps in the reactions of cyanuric chloride with n-butyl amine in N-methyl pyrrolidone (NMP) and with morpholine in isopropanol (i-PrOH) were followed kinetically. The ratio of the exchange rates of the first, the second and the third chlorine atom was unexpectedly high in both cases. The reactions of n-butylamino dichlorotriazine with several amines were studied kinetically both in NMP and in i-PrOH. Linear free-energy relationships exist both between our values in NMP and in isopropanol and between our values and reaction rates of p-nitro fluorobenzene with the corresponding amines (in DMSO) determined by Suhr.

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