Restriction fragment length polymorphism at the HLA-C locus

We have used the HLA-C-specific DNA probe pC250 to investigate restriction fragment length polymorphism (RFLP) at the HLA-C locus. Genomic Southern blot hybridization included DNA prepared from a panel of homozygous typing cells representing serological specificities Cw1 to Cw8 and also from samples representing Cw blanks. Although many restriction nucleases failed to reveal any polymorphism, RFLPs were evident with Taq I, Pvu II, Bst XI, Nde 1, and Nci I in addition to the previously reported Eco RI. In the case of Bst XI, a unique RFLP defined a subset of serologically defined Cw blanks. Comparison of RFLP sizes with restriction fragment lengths obtained from the known HLA-Cw3 gene sequence permitted the localization of intragenic C locus RFLLs and the identification of a variable Taq I site in the second intron, a variable Nci I site near the end of the fourth exon, and a variable Pvu lI site in the fifth intron.     

Characterization of a class of small auxin-inducible soybean polyadenylated RNAs

Four new auxin-responsive RNAs from soybean (Glycine max (L.) Merr., var. Wayne) are described. The RNAs were identified by hybridization to three cDNA probes obtained from a library enriched for sequences which increase in abundance within 60 min after 2,4-D (2,4-dichlorophenoxyacetic acid) treatment. These RNAs appear to define a new class of small (i.e. approximately 550 nucleotides) RNAs that respond extremely rapidly to application of exogenous auxin. In excised elongating hypocotyl sections, an increase in the abundance of these RNAs can be detected 2 to 5 min after treatment with 50 M 2,4-D. This response is half maximal after 10 min and reaches steady state in 60 min. RNA blot analysis shows that these RNAs are expressed differentially in various parts of the seedling. The degree of inducibility by auxin is also organ-specific, with the elongating hypocotyl being the most responsive of the organs tested. The RNAs display identical response specificities with one exception. Accumulation of one RNA, designated 10A, is completely abolished by simultaneous addition of cycloheximide and 2,4-D. This RNA also displays a different 2,4-D dose response than other RNAs examined. These results suggest that more than one mechanism is involved in rapid modulation of gene expression by auxin.     

C-band polymorphisms of chromosome 9: quantification by Ce-bands

Summary C-band polymorphisms of chromosome 1 can be quantified by C_e bands visualized using oblique epi-illumination. In this paper the polymorphic region of chromosome 9, including variants such as 9qh+, inversions, and translocations, was analyzed in a total of 1860 chromosomes from 20 individuals and 8 fetuses. In this sample we found between zero and five C_e bands on 9q and between zero and four C_e bands on 9p with a maximum of five C_e bands per chromosome. On the basis of these observations at least 19 different polymorphic patterns can be expected theoretically, 15 of which were observed in our sample. Among these, five polymorphic C_e-band classes were distinguishable by the method presented. Considering both homologues, 5²=25 quantitatively discernible chromosome 9 pairs may exist.     

Limiting factors for seed production in Cynoglossum officinale

Summary Over three years of study, small plants of Cynoglossum officinale consistently produced more flowers per unit of dry weight than large plants. In contrast to earlier results, weight of all seeds tended to increase more than proportional to size. As a result a positive correlation existed between seed set per flower and plant size. The correlation between the mean number of pollinator visits per flower and size was positive but not significant. In a field experiment we found that resources rather than pollen were limiting seed set. Thus, it is unlikely that enhanced pollination of the largest plants causes the size-dependency of seed set per flower. Alternative hypotheses are discussed briefly.Publication of the Meijendel Comité, New Series No. 96     

Phosphoribosyl pyrophosphate and the measurement on inorganic pyrophosphate in plant tissues

This work provides further evidence that plants contain appreciable amounts of inorganic pyrophosphate (PPi), and that breakdown of phosphoribosyl pyrophosphate (PPRibP) does not contribute significantly to the PPi detected in plant extracts. Inorganic pyrophosphate in extracts of the roots of Pisum sativum L., clubs of the spadices of Arum maculatum L., and the developing endosperm of Zea mays L. was assayed with pyrophosphate fructose 6-phosphate 1-phosphotransferase (EC 2.7.1.90), and with sulphate adenyltransferase (EC 2.7.7.4). The two different assays gave the same value for PPi content, and for recovery of added PPi. It was shown that PPRibP is converted to PPi during the extraction of PPi. However, the amounts of PPRibP in clubs of A. maculatum and the developing endosperm of Z. mays were negligible in comparison with the contents of PPi.Abbreviations EDTA ethylenediaminetetraacetic acid - PFK(PPi) pyrophosphate fructose 6-phosphate 1-phosphotransferase - PPi inorganic pyrophosphate - PPRibP phosphoribosyl pyrophosphate     

Association of folic acid with rat liver microsomes

Summary Shin et al. (Biochim Biophys Acta 444: 794–801, 1976) described the subcellular location of [³H]folic acid after injection into rats. The microsomal fraction of the liver contained relatively large amounts of tracer initially but lower amounts at later times. Because of the heterogeneous nature of the microsomal fraction of the liver we re-examined the nature of the folate binding fraction. The location of injected [³H]folic acid resembled that of the microsomes derived from the plasma membrane, where ultracentrifugal analysis was conducted in the presence and absence of cesium ions. The location of the folate did not resemble that of microsomes derived from the endoplasmic reticulum (ER). One of the marker enzymes of the ER was the vitamin K-dependent carboxylase. A simple method for reducing vitamin K is described.     

Flavonoid aglycones from the leaf surfaces of someLabiatae species

The distribution of excreted flavonoid aglycones within the familyLabiatae was studied and differences were found, especially in the A-ring substitution patterns. Thus, 5,7-dihydroxy-6-methoxyflavones with substituted B-rings are characteristic of species ofSalvia (sect.Salvia),Rosmarinus andOcimum; 5,7-dihydroxy-6,8-dimethoxyflavones occur only inOcimum and 5,6-dihydroxy-7,8-dimethoxyflavones inThymus and related species. Members of the two subfamiliesLamioideae andNepetoideae produce exudate flavonoids, but some genera are devoid of these compounds. There is a correlation between the habitat where the plant grows and production of these compounds, the species from (semi-)arid habitats being those which generally accumulate external flavonoids.