The purification and characterization of a fatty acid binding protein specific to pig (Sus domesticus) adipose tissue.

Western-blot analysis using antiserum to 3T3-L1-cell fatty acid binding protein (FABP) revealed that pig adipose tissue contains a 15 kDa protein immunologically similar to the murine protein. This 15 kDa protein was purified from pig adipose tissue by sequential application of Sephadex G-50 gel filtration, cation exchange and covalent chromatography on Thiol-Sepharose-4B. The purity of the pig protein was established by two-dimensional polyacrylamide-gel electrophoresis. Isoelectric focusing indicated that the pig adipose FABP (a-FABP) exists with two charge isoforms (pI 5.1 and 5.2), both of which persist after delipidation. The N-terminus of the purified pig a-FABP was blocked; however, cleavage with CNBr allowed recovery of a 12-amino-acid peptide which was identical with the murine a-FABP sequence (residues 36-48) at 10 of 12 positions. The pig a-FABP bound 12-(9-anthroyloxy)oleic acid saturably and stoichiometrically, with an apparent dissociation constant of 1.0 microM. Northern-blot analysis using the cDNA for the murine 3T3-L1 FABP revealed that the pig a-FABP was expressed exclusively in adipose tissue.     

The evolutionary origin of the 35 kb circular DNA of Plasmodium falciparum: new evidence supports a possible rhodophyte ancestry

In common with other Apicomplexan parasites, Plasmodium falciparum carries two extrachromosomal DNAs, one of which, the 6 kb element, is undoubtedly mitochondrial. The second, generally referred to as the 35 kb circle, is of unknown provenance, but the nature and organization of its genetic content makes a mitochondrial association unlikely and the molecule has features reminiscent of plastid genomes. We now report the occurrence on the circle of an open reading frame specifying a predicted 470 amino acid protein that shares more than 50% identity with a gene currently known only on the plastome of red algae. This high degree of conservation confirms the 35 kb circle's plastid ancestry, and we speculate that it may have originated from the rhodoplast of an ancient red algal endosymbiont in the progenitor of the Apicomplexa.     

Volume changes correlate with entropies and enthalpies in the formation of nucleic acid homoduplexes: Differential hydration of A and B conformations

We have used a combination of densimetric, calorimetric, and uv absorption techniques to obtain a complete thermodynamic characterization for the formation of nucleic acid homoduplexes of known sequence and conformation. The volume change ΔV accompanying the formation of four duplexes was interpreted to reflect changes in hydration based on the electrostriction phenomenon. In 10 mM sodium phosphate buffer at pH 7, the magnitude of the measured ΔV's ranged from ?2.0 to +7.2 ml/mol base pair and followed the order of poly(rA) · poly(dT) ～ poly(dA) · poly(dT) < poly(rA) · poly(dU) ～ poly(rA) · poly(rU). Inclusion of 100 mM NaCl in the same buffer gave the range of ?17.4 to ?2.3 mL/mol base pair and the following order: poly(dA) · poly(dT) < poly(rA) · poly(dT) < poly(rA) · poly(rU) ～ poly(rA) ～ polyr(dU). Standard thermodynamic profiles of forming these duplexes from their corresponding complementary single strands indicated similar free energies that resulted from the compensation of favorable enthalpies with unfavorable entropies along with a similar counterion uptake at both ionic strengths. The differences in these compensating effects of entropy and enthalpy correlated very well with the volume change measurements in a manner suggesting that the homoduplexes in the B conformation are more hydrated than are those in the A conformation. Moreover, the increased thermal stability of these homoduplexes resulted from an increase in the salt concentration corresponding to larger hydration levels as reflected by the ΔV results. © 1993 John Wiley & Sons, Inc.     

Cytological and molecular characterization of a chromosome interchange and addition lines in Cadet involving chromosome 5B of wheat and 6Ag of Lophopyrum ponticum

Efforts to transfer wheat curl mite (Eriophyes tulipae Keifer) resistance from Lophopyrum ponticum 10X (Podb.) Love to bread wheat (Triticum aestivum L.) have resulted in the production of a number of cytogenetic stocks, including an addition line of 6Ag, a ditelo addition line, and a wheat-Lophopyrum translocation line. Characterization of these lines with C-banding, in situ hybridization with a Lophopyrum species-specific repetitive DNA probe (pLeUCD2), and Southern blotting with pLeUCD2 and a 5S ribosomal DNA probe (pScT7) confirmed that the distal portion of the short arm of 6Ag was translocated onto the distal portion of 5BS (5BL. 5BS-6AgS). It was also determined that the ditelo addition was an acrocentric chromosome of 6AgS.     

GENETIC DIVERSITY IN THE MONOECIOUS HYDROPHILE CERATOPHYLLUM (CERATOPHYLLACEAE)

This study surveys genetic variation in two clonal, monoecious, water-pollinated species that differ in their extent of sexuality and distributional range. Electrophoresis was used to quantify allozyme variability in 12 Wisconsin populations of the widespread Ceratophyllum demersum and the rare C. echinatum. Electrophoretic data indicate that populations of both species have low levels of sexual recombination, low levels of variation, and are structured genetically like inbreeding terrestrial plants. Ceratophyllum populations differ from “typical” clonal terrestrial plants by lower genetic diversity, lower proportions of multiclonal populations, and fewer genotypes per population. In two populations where sexual recombination is documented, heterozygosity is low with significant deficiencies. Monoecy in Ceratophyllum may be related to historical evolutionary factors, whereas vegetative reproduction has a greater influence on the genetic population structure of extant populations. The low genetic identity between C. demersum and C. echinatum supports their recognition as distinct species.     

MINIMAL MALE/FEMALE TRADEOFFS IN ZIZANIA PALUSTRIS,A MONOECIOUS ANNUAL GRASS

Because a male/female resource tradeoff is a basic assumption of many models of sex allocation in cosexual plants, statistical and manipulative methods were used to look for evidence of intersexual resource conflicts in Zizania palustris. In this monoecious grass, male and female investments overlap in time within each panicle and on successive panicles, and sex allocation quickly responds to environmental changes. Nevertheless, no negative correlations were found between the numbers of florets of each sex within panicles, on consecutive panicles, or on whole plants. Removing immature fruits or florets of either sex did not significantly increase subsequent investment in the other sex. The one significant tradeoff was slightly lower total fruit production on plants with exceptionally large male investment. Wild rice, therefore, fits the tradeoff assumption of sex allocation models at the population level but rarely at the individual level.     

Competence pheromone, oligopeptide permease, and induction of competence in Streptococcus pneumoniae

An unmodified heptadecapeptide pheromone capable of eliciting competence for genetic transformation in Streptococcus pneumoniae has recently been identified and characterized. In considering possible signaltransduction mechanisms for the peptide, the previously characterized Ami oligopeptide permease and the three highly homologous oligopeptide-binding lipoproteins, AmiA. AliA, and AliB, appeared to be good candidates for receptors. We therefore compared the spontaneous transformability of Ami, AliA and AliB mutants to that of an isogenic wild-type strain and we investigated the response of the various mutants to treatment with synthetic competence-stimulating peptide (CSP). Our results clearly demonstrate that neither Ami nor any of the three highly homologous oligopeptide-binding lipoproteins identified so far in S. pneumoniae are required for competence induction following treatment with synthetic CSP. Although the existence of a fourth unidentified oligopeptide-binding lipoprotein and/or a second oligopeptide permease operon could not be completely ruled out, we favour the hypothesis that CSP signal transmission rather involves a two-component regulatory system. Although none of the single or double Ami and Ali mutants tested appeared severely affected for competence, an exceptional aliB plasmid-insertion mutation abolished competence completely. In addition, the triple AmiA-AliA-AliB mutant differed from wild type in showing no sharp peak of competence but exhibiting transformability throughout the exponential phase of growth. These and previous observations are discussed and a general hypothesis is proposed to account for the modulation of competence by peptide permease mutants in S. pneumoniae.     

Biology and life cycle ofAtelocauda koae,an unusual demicyclic rust

Atelocauda koae, a rust of the native HawaiianAcacia koa, is considered as a demicyclic species, having spermogonial, aecial, and telial states, but is unusual in production of aeciospores simultaneously with teliospores rather than consecutively. Host inoculation with spores of each state separately confirmed that the life cycle was perpetuated by the telial state, but the aeciospores, while capable of germination and stomal penetration, did not produce detectable infection. This rust therefore behaves as a microcyclic species, and appears to be in evolutionary transition toward this reduced state. Teliospores produced vestigial, permanently attached basidiosopores which germinated to produce infective hyphae. The hyphae entered the host either through stomata or penetrated the epidermis directly, with the latter method being more common. Unusual nuclear associated with teliospore germination, in which meiosis occurs in more than one diploid nucleus was observed, in confirmation of an earlier study.