Systematic studies of Pinus balfouriana based on volatile terpenoids from wood and needles and on seed morphology

Essential oil from wood and from needles of Pinus balfouriana, growing in six geographically well-separated locations in California, was analysed by GLC. Several monoterpenoid components, in particular -pinene from needles, were found to be usable for distinguishing between trees from the northern and southern parts of the geographic range. Similarity coefficients were calculated and dendrograms constructed. These demonstrated the distinct separation of the northern from the southern populations, and thus substantiated the proposal by Mastrogiuseppe to regard the southern populations as a subspecies. While the northern populations exhibited a tendency to produce larger seeds with longer wings, the difference was of only moderate diagnostic value.     

Membrane surface properties of sheep erythrocytes,an immunological reagent,after different treatments as reflected by partition in two-polymer aqueous phases

Sheep erythrocytes (E) which, with or without certain treatments, are currently used as “immunological reagents” to detect cells with specific receptors (by rosette-formation) have been partitioned in two-polymer aqueousphase systems selected so as to reflect charge-associatedor lipid-related membrane surface properties. We have found that the partitioning behavior of E is not affected in these phases by reacting the cells with anti-E antibody (either IgG or IgM), forming EA. The additional binding of complement to the cell-antibody complex, forming EAC, results, however, in a marked decrease in the partition coefficient,K. Apparently both the charge-associated and hydrophobic properties reflected by partitioning remain accessible to the phase polymers when the cells are coated with antibody, but are not with the addition of complement. It is interesting that EA can still rosette with T-lymphocytes (14), a property of E, while the additional coating with complement results in EAC which does not appreciably do so (26). Neuraminidase or trypsin treatments of E, which yield Es having quite different rosetting properties with T-lymphocytes (14), cause increasedKs and unchangedKs, respectively, in phases reflecting lipid-related surface properties. Either treatment causes reducedKs of E in charged-phase systems. Neuraminidase treatment also results in a reduced electrophoretic mobility of E, while trypsin treatment is not detectable by cell electrophoresis (25). We are currently studying the possible usefulness of employing cell electrophoresis and cell partitioning in charged-phase systems jointly to obtain information on events occurring at the shear plane versus those occurring deeper in the membrane.     

Biosynthesis of sesquiterpenes in Hymenaea inferred from their quantitative co-occurrence

Leaf pocket resins of 11 species of the tropical arborescent genus Hymenaea are virtually identical qualitatively, but of widely varying quantitative proportions. Within this large range of variability, several strong positive quantitative correlations between resin constituents were found, especially between caryophyllene and β-humulene and between γ-muurolene and δ-cadinene. These data lead to clarification of sesquiterpene biosynthetic routes in Hymenaea. In addition, quantitative relationships found among caryophyllene, α- and β-selinene, γ-muurolene and δ-cadinene are explained only with difficulty by long accepted biosynthetic pathways, and the intermediacy of germacrenes is suggested.     

The configuration of the sesquiterpenoid 4-hydroxy-myoporone (athanagrandione)

The conversion of eremoacetal to (?)-1-(furan-3-yl)-4-hydroxy-4,8-dimethylnonane-1,6-dione establishes the configuration of (?)-4-hydroxymyoporone (athanagrandione) as R.     

Structural consequences of metallothionein dimerization: solution structure of the isolated Cd4-alpha-domain and comparison with the holoprotein dimer

The NMR determination of the structure of Cd(7)-metallothionein was done previously using a relatively large protein concentration that favors dimer formation. The reactivity of the protein is also affected under this condition. To examine the influence of protein concentration on metallothionein conformation, the isolated Cd(4)-alpha-domain was prepared from rabbit metallothionein-2 (MT 2), and its three-dimensional structure was determined by heteronuclear, (1)H-(111)Cd, and homonuclear, (1)H-(1)H NMR, correlation experiments. The three-dimensional structure was refined using distance and angle constraints derived from these two-dimensional NMR data sets and a distance geometry/simulated annealing protocol. The backbone superposition of the alpha-domain from rabbit holoprotein Cd(7)-MT 2 and the isolated rabbit Cd(4)-alpha was measured at a RMSD of 2.0 A. Nevertheless, the conformations of the two Cd-thiolate clusters were distinctly different at two of the cadmium centers. In addition, solvent access to the sulfhydryl ligands of the isolated Cd(4)-alpha cluster was 130% larger due to this small change in cluster geometry. To probe whether these differences were an artifact of the structure calculation, the Cd(4)-alpha-domain structure in rabbit Cd(7)-MT 2 was redetermined, using the previously defined set of NOEs and the present calculation protocol. All calculations employed the same ionic radius for Cd(2+) and same cadmium-thiolate bond distance. The newly calculated structure matched the original with an RMSD of 1.24 A. It is hypothesized that differences in the two alpha-domain structures result from a perturbation of the holoprotein structure because of head-to-tail dimerization under the conditions of the NMR experiments.     

Origin of a substantial fraction of human regulatory sequences from transposable elements

Transposable elements (TEs) are abundant in mammalian genomes and have potentially contributed to their hosts' evolution by providing novel regulatory or coding sequences. We surveyed different classes of regulatory region in the human genome to assess systematically the potential contribution of TEs to gene regulation. Almost 25% of the analyzed promoter regions contain TE-derived sequences, including many experimentally characterized cis-regulatory elements. Scaffold/matrix attachment regions (S/MARs) and locus control regions (LCRs) that are involved in the simultaneous regulation of multiple genes also contain numerous TE-derived sequences. Thus, TEs have probably contributed substantially to the evolution of both gene-specific and global patterns of human gene regulation.     

Linkage between low-density lipoprotein and igk light-chain genes in rabbits

The rabbit geneLpq, which codes for a low-density serum lipoprotein², is linked (34.6 ± 5.3 centimorgans) to the Ig kappa light-chain gene (Ab). There is no evidence thatLpq is linked to another gene,Prt, that was previously found to be linked to theAb gene. This suggests that the gene order for the three genes isPrt- Ab- Lpq. Abbreviations used in this paper Ig immunoglobulin - a the heavy-chain variable-region geneAa - b the kappa light-chain geneAb - q the low-density serum lipoprotein geneLpq     

Absence of a correlation between cyclic nucleotide fluctuations and cell cycle progression

The levels of cAMP and cGMP were determined throughout the mitotic cycle of two independent strains of the naturally synchronous slime mold, Physarum polycephalum. The normal range of values was approx. 0.5–2.5 pmoles cAMP/ mg protein and 0.01–0.08 pmoles cGMP/mg protein. In our standard laboratory strain, there was no systematic pattern to the variations in the values within the normal range and no unique time in the cycle when values significantly above normal were noted. In the other strain recently cultured from spherules, elevated levels of cGMP, but not cAMP, were observed in late G2 and in the S phase. The data suggest that elevated levels of these cyclic nucleotides are not required for normal progression of the Physarum mitotic cycle which is unperturbed by artificial synchronizing procedures.