Evidence for African origins of founders of the asiatic lion species survival plan

The Asiatic lion (Panthera leo persica) exists in the wild as a single relict population of approximately 250 individuals in the protected Gir Forest Sanctuary in western India. In 1981, a species survival plan (SSP) for the Asiatic lion was established by the American Association of Zoological Parks and Aquariums to manage the 200 + descendants of Asiatic lions in captivity in western zoological facilities. This captive population was derived from seven founders. In order to compare the genetic structure of the Gir Forest population with that of the captive SSP population, a genetic survey of 46 electrophoretic allozyme systems resolved from extracts of lion blood was undertaken by using 29 SSP Asiatic lions and 28 wild-caught or captive-bred lions maintained at the Sakkarbaug Zoo in India but originally derived from the Gir Forest. The Gir lion population was found to be genetically monomorphic at each of 46 allozyme loci. This was in contrast to several African lion (Panthera leo leo) populations, which show moderate levels of allozyme variation at the same loci. The SSP lion population was polymorphic at three allozyme loci (IDHI, TF, and PTI) for alleles that were previously found only in African lion populations. Pedigree analysis of the genetic transmission of these three biochemical loci demonstrated that two of the five primary founder animals of the SSP Asiatic lion population (a breeding pair originally imported from the Trivandrum Zoo in southern India) were descendants of the African subspecies. Three other founder animals were pure Asian. A retrospective SSP pedigree analysis of two morphologic characters (prominent abdominal fold and pairing of infraorbital foramen) that are partially diagnostic for persica vs leo was consistent with this conclusion as well. The implications for the management of small captive populations of threatened species and of the Asiatic lion SSP population are discussed.     

Response of V79 cells to N-methyl-N'-nitro-N-nitrosoguanidine (MNNG) treatment: inhibition of poly(ADP-ribose) and topoisomerase activity.

MNNG-induced killing of V79 cells has been found to be enhanced on inhibition of topoisomerase II activity by nalidixic acid and poly(ADP-ribose) polymerase synthesis by benzamide. Using these 2 inhibitors in conjunction after MNNG treatment, some overlap in the functions of these 2 enzymes was observed. Nalidixic acid and benzamide were found to suppress the yields of mutations and SCEs induced by MNNG. Benzamide was more effective in suppressing the mutation yield whereas nalidixic acid was more effective in suppressing SCEs. A model based on the relative requirement of topoisomerase and poly(ADP-ribose) for the repair of different types of damage has been proposed to explain the results.     

Fertile Transgenic Indica Rice Produced by Expression of Maize Ubiquitin Promoter-bar Chimaeric Gene in the Protoplasts

We report production of fertile transgenic Indica rice plants by transferring a chimaeric construct consisting of promoter, first exon and intron of maize ubiquitin gene (Ubi-1) and the coding sequences of the bar gene from Streptomyces hygroscopicus to the rice protoplasts through electroporation. In total, 11 plants were regenerated. All of them were fertile and set seeds on maturity. These plants were resistant to high concentration of PPT (400 mg l^?1) which was otherwise toxic to the untransformed controls. The gene was inherited to the progenies of the five plants in Mendelian ratio.     

Role of the origin of transfer in termination of strand transfer during bacterial conjugation.

Conjugal transfer of the broad-host-range plasmid R1162 is initiated and terminated at the nic site within the 38-bp origin of transfer (oriT). Termination involves ligation of the transferred single strand by the plasmid-encoded MobA protein. Several different assays were used to identify the oriT DNA required for termination. For plasmids containing two oriTs, with transfer initiated at one and terminated at the other, the inverted repeat within oriT is important for termination. Deletion of the outer arm reduces the termination frequency; those terminations that do occur probably depend upon nicking at this oriT prior to transfer. The locations of second-site suppressor mutations indicate that base pairing between the arms of the inverted repeat is important for termination. In vitro, the inverted repeat is not required for specific cleavage of single-stranded DNA at nic, but competition experiments indicate that oriTs with the inverted repeat are preferentially cleaved. We propose that the function of the oriT inverted repeat is to trap the plasmid-encoded MobA protein at the end of a round of strand transfer, thus ensuring that the protein is available for the ligation step.     

A surface polysaccharide of Escherichia coli O111 contains O-antigen and inhibits agglutination of cells by O-antiserum

The repeating pentasaccharide of O-antigen from Escherichia coli O111 contains galactose, glucose, N-acetylglucosamine, and colitose, the latter representing the major antigenic determinant. Phenol extraction of this strain was previously shown to release two fractions (I and II) containing O-antigen carbohydrate, and both fractions were believed to be lipopolysaccharide. We have now characterized fractions I and II and conclude that only fraction II represents lipopolysaccharide. Fraction II contains phosphate, 2-keto-3-deoxyoctonate, beta-hydroxymyristic acid, and potent endotoxin activity, whereas fraction I was deficient in all of these properties of the lipid A and core oligosaccharide regions of lipopolysaccharide. Fractions I and II each represented 50% of the total cellular O-antigen, and both were present on the cell surface. Both fractions were metabolically stable, and no precursor-product relationship existed between them. Fraction II had a number-average molecular weight of 15,800, corresponding to an average of 12 O-antigen repeats per molecule. In contrast, fraction I had a number-average molecular weight of 354,000, corresponding to an average of 404 O-antigen repeats per molecule. Before heat treatment, cells of E. coli O111 are poorly agglutinated by O-serum; although this indicates the presence of a capsule, the corresponding K-antigen was never detected. We conclude that fraction I, when present on the cell surface, inhibits agglutination of unheated cultures of E. coli O111 by O-serum because: (i) a variant strain which lacks fraction I was agglutinated by O-serum without prior heating; (ii) erythrocytes coated with purified fraction I behaved like bacteria containing fraction I in showing inhibition of O-serum agglutination; and (iii) heat treatment released fraction I and rendered bacterial cells agglutinable in O-serum.     

The R-type lipopolysaccharides of Neisseria meningitidis

The lipopolysaccharides of all the different serogroups of Neisseria meningitidis are of the "R" type despite the morphologically smooth appearance and the demonstrated virulence of the organisms from which they were derived. This was confirmed when each of the lipopolysaccharides was found to be devoid of detectable O-antigen side chains, giving only a low "molecular" weight core oligosaccharide when subjected to mild acid hydrolysis. The cores were modified by dephosphorylation and subjected to sugar and methylation analysis by gas-liquid chromatography. Although all the different cores contained identical components (glucose, galactose, glucosamine, heptose, and 2-keto-3-deoxyoctonate) they could be separated into three distinct categories according to their galactose:glucose ratios. These categories are typified by the cores obtained from groups A, C, and 29-e which have galactose:glucose ratios of 1:2, 2:2, and 2:1, respectively. The modified cores were methylated and analyzed by gas chromatography--mass spectrometry and on the basis of differences in the derived methylated sugars the cores could again be divided into the same three categories as above. This structural diversity also results in some serological specificity as demonstrated by the complete serogroup specificity of the group A lipopolysaccharide.     

Biosynthesis and regulation of fructose-1,6-bisphosphatase and phosphofructokinase in Saccharomyces cerevisiae grown in the presence of glucose and gluconeogenic carbon sources.

The mode of synthesis and the regulation of fructose-1,6-bisphosphatase (Fbpase), a gluconeogenic enzyme, and phosphofructokinase (PFK), a glycolytic enzyme, were investigated in Saccharomyces cerevisiae after growth in the presence of different concentrations of glucose or various gluconeogenic carbon sources. The activity of FBPase appeared in the cells after the complete disappearance of glucose from the growth medium with a concomitant increase of the pH and no significant change in the levels of accumulated ethanol. The appearance of FBPase activity following glucose depletion was dependent upon the synthesis of protein. The FBPase PFK were present in glucose-, ethanol-, glycerol-, lactate-, or pyruvate-grown cells; however, the time of appearance and the levels of both these enzymes varied. The FBPase activity was always higher in 1% glucose-grown cells than in cells grown in the presence of gluconeogenic carbon sources. Phosphoglucose isomerase activity did not vary significantly. Addition of glucose to an FBPase and PFK synthesizing culture resulted in a complete loss, followed by a reappearance, of PFK activity. In the presence of cycloheximide the disappearance of glucose and the changes in the levels of FBPase and PFK were decreased significantly. It is concluded that S. cerevisiae exhibits a more efficient synthesis of FBPase after the exhaustion of glucose compared to the activity present in cells grown in the presence of exogenous gluconeogenic carbon sources. Two metabolically antagonistic enzymes, FBPase and PFK, are present during the transition phase, but not during the exponential phase, of growth, and the decay or inactivation of these enzymes in vivo may be dependent upon a glucose-induced protease activity.